Search results for: injection point

Authors: Chris Cadman, Marcel Strauss

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Background: In 2020, the University Hospital Wishaw in the United Kingdom became the centre for trauma and orthopaedics within its health board. This resulted in the majority of patients with suspected cauda equina syndrome (CES) being assessed and imaged at this site, putting an increased demand on MR imaging and displacing other previous activity. Following this transition, imaging requests for CES did not always follow national guidelines and would often be missing important clinical and safety information. There also appeared to be a very low positive scan rate compared with previously reported studies. In an attempt to improve patient selection and reduce the burden of CES imaging at this site clinical audit was performed. Methods: A total of 250 consecutive patients imaged to assess for CES were evaluated. Patients had to have presented to either the emergency or orthopaedic department acutely with a presenting complaint of suspected CES. Patients were excluded if they were not admitted acutely or were assessed by other clinical specialities. In total, 233 patients were included. Requests were assessed for appropriate clinical history, accurate and complete clinical assessment and MRI safety information. Clinical assessment was allocated a score of 1-6 based on information relating to history of pain, level of pain, dermatomes/myotomes affected, peri-anal paraesthesia/anaesthesia, anal tone and post-void bladder volume with each element scoring one point. Images were assessed for positive findings of CES, acquired spinal stenosis or nerve root compression. Results: Overall, 73% of requests had a clear clinical history of CES. The urgency of the request for imaging was given in 23% of cases. The mean clinical assessment score was 3.7 out of a total of 6. Overall, 2% of scans were positive for CES, 29% had acquired spinal stenosis and 30% had nerve root compression. For patients with CES, 75% had acute neurological signs compared with 68% of the study population. CES patients had a mean clinical history score of 5.3 compared with 3.7 for the study population. Overall, 95% of requests had appropriate MRI safety information. Discussion: it study included 233 patients who underwent specialist assessment and referral for MR imaging for suspected CES. Despite the serious nature of this condition, a large proportion of imaging requests did not have a clear clinical query of CES and the level of urgency was not given, which could potentially lead to a delay in imaging and treatment. Clinical examination was often also incomplete, which can make triaging of patients presenting with similar symptoms challenging. The positive rate for CES was only 2%, much below other studies which had positive rates of 6–40% with a large meta-analysis finding a mean positive rate of 19%. These findings demonstrate an opportunity to improve the quality of imaging requests for suspected CES. This may help to improve patient selection for imaging and result in a positive rate for CES imaging that is more in line with other centres.

Keywords: cauda equina syndrome, acute back pain, MRI, spine

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Authors: S. Jimenez, R.Duarte, J.Sanchez-Choliz, I. Villanua

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There is a certain consensus in economic literature about the factors that have influenced in historical differences in growth rates observed between developed and developing countries. However, it is less clear what elements have marked different paths of growth in developed economies in recent decades. R&D has always been seen as one of the major sources of technological progress, and productivity growth, which is directly influenced by technological developments. Following recent literature, we can say that ‘innovation pushes the technological frontier forward’ as well as encourage future innovation through the creation of externalities. In other words, productivity benefits from innovation are not fully appropriated by innovators, but it also spread through the rest of the economies encouraging absorptive capacities, what have become especially important in a context of increasing fragmentation of production This paper aims to contribute to this literature in two ways, first, exploring alternative indexes of R&D flows embodied in inter-country, inter-sectorial flows of good and services (as approximation to technology spillovers) capturing structural and technological characteristic of countries and, second, analyzing the impact of direct and embodied R&D on the evolution of labor productivity at the country/sector level in recent decades. The traditional way of calculation through a multiregional input-output framework assumes that all countries have the same capabilities to absorb technology, but it is not, each one has different structural features and, this implies, different capabilities as part of literature, claim. In order to capture these differences, we propose to use a weight based on specialization structure indexes; one related with the specialization of countries in high-tech sectors and the other one based on a dispersion index. We propose these two measures because, as far as we understood, country capabilities can be captured through different ways; countries specialization in knowledge-intensive sectors, such as Chemicals or Electrical Equipment, or an intermediate technology effort across different sectors. Results suggest the increasing importance of country capabilities while increasing the trade openness. Besides, if we focus in the country rankings, we can observe that with high-tech weighted R&D embodied countries as China, Taiwan and Germany arose the top five despite not having the highest intensities of R&D expenditure, showing the importance of country capabilities. Additionally, through a fixed effects panel data model we show that, in fact, R&D embodied is important to explain labor productivity increases, in fact, even more that direct R&D investments. This is reflecting that globalization is more important than has been said until now. However, it is true that almost all analysis done in relation with that consider the effect of t-1 direct R&D intensity over economic growth. Nevertheless, from our point of view R&D evolve as a delayed flow and it is necessary some time to be able to see its effects on the economy, as some authors have already claimed. Our estimations tend to corroborate this hypothesis obtaining a gap between 4-5 years.

Keywords: economic growth, embodied, input-output, technology

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Authors: Eleanor F. Willard

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The attrition rate on distance learning courses can be high. This research examines how online students often react when faced with poor results. Using q methodology, it was found that the emotional response level and the type of social support sought by students were key influences on their attitude to failure. As educational and psychological researchers, we are adept at measuring learning and achievement, but examining attitudes towards barriers to learning are not so well researched. The distance learning student has differing needs from onsite learners and, as the attrition rate is notoriously high in the online student population, examining learners’ attitude towards adversity and barriers is important. Self-report measures such as questionnaires are useful in terms of ascertaining levels of constructs such as resilience and academic confidence. Interviewing, too, can gain in depth detail of the opinions of such a population, but only in individuals. The aim of this research was to ascertain what the feelings and attitudes of online students were when faced with a setback. This was achieved using q methodology due to its use of both quantitative and qualitative methodology and its suitability for exploratory research. The emphasis with this methodology is the attitudes, not the individuals. The work was focused upon a population of distance learning students who attended a school on site for one week as part of their studies. They were engaged in a psychology masters conversion course and, as such, were graduate students. The Q sort had 30 items taken from the Academic Resilience Scale (ARS-30). The scale items represent three constructs; perseverance, reflecting (including adaptive help-seeking) and negative affect. These are widely acknowledged as being relevant concepts underpinning psychological resilience. The q sort was conducted with 19 students in total. This is done by participants arranging statement cards regarding how similar to themselves they believe each statement to be. This was done after reading a vignette describing an experience of academic failure. Commonalities and differences between the sorts from all participants are then analyzed in terms of correlations and response patterns. Following data collection, the participants' responses were initially analyzed and the key perspectives (factors) to emerge were labelled ‘persevering individuals’ and ‘emotional networkers’. The differences between the two perspectives centre around the level of emotion felt when faced with barriers and the extent that students enlist the help of others inside and outside of the university. The dominant factor to emerge from the sorts of ‘persevering individuals’ demonstrated that many distance learners are tenacious. However, for other students, the level of emotional and social support is pivotal in helping them complete their studies when facing adversity. This was demonstrated by the ‘emotional networkers’ perspective. This research forms a starting point for further work on engaging and retaining online students at university and can potentially provide insight into how universities can lower attrition rates on distance learning courses.

Keywords: academic resilience, distance learning, online learning, q methodology

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Authors: Rayanne Branco Dos Santos Lima, Lorena Pinheiro Barbosa, Kamila Ferreira Lima, Victor Manuel Tegoma Ruiz, Monyka Brito Lima Dos Santos, Maria Wendiane Gueiros Gaspar, Luzia Camila Coelho Ferreira, Leandro Cardozo Dos Santos Brito, Deyse Maria Alves Rocha

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Introduction: The lack of regulation of the baby's sleep-wake pattern in the first years of life affects the health of thousands of women. Maternal sleep deprivation can trigger or aggravate psychosomatic problems such as depression, anxiety and stress that can directly influence maternal safety, with consequences for the baby's and mother's sleep. Such conditions can affect the family's quality of life and child development. Objective: To correlate maternal security with maternal state anxiety scores and the mother's and baby's total sleep time. Method: Cross-sectional study carried out with 96 mothers of babies aged 10 to 24 months, accompanied by nursing professionals linked to a Federal University in Northeast Brazil. Study variables were maternal security, maternal state anxiety scores, infant latency and sleep time, and total nocturnal sleep time of mother and infant. Maternal safety was calculated using a four-point Likert scale (1=not at all safe, 2=somewhat safe, 3=very safe, 4=completely safe). Maternal anxiety was measured by State-Trait Anxiety Inventory, state-anxiety subscale whose scores vary from 20 to 80 points, and the higher the score, the higher the anxiety levels. Scores below 33 are considered mild; from 33 to 49, moderate and above 49, high. As for the total nocturnal sleep time, values between 7-9 hours of sleep were considered adequate for mothers, and values between 9-12 hours for the baby, according to the guidelines of the National Sleep Foundation. For the sleep latency time, a time equal to or less than 20 min was considered adequate. It is noteworthy that the latency time and the time of night sleep of the mother and the baby were obtained by the mother's subjective report. To correlate the data, Spearman's correlation was used in the statistical package R version 3.6.3. Results: 96 women and babies participated, aged 22 to 38 years (mean 30.8) and 10 to 24 months (mean 14.7), respectively. The average of maternal security was 2.89 (unsafe); Mean maternal state anxiety scores were 43.75 (moderate anxiety). The babies' average sleep latency time was 39.6 min (>20 min). The mean sleep times of the mother and baby were, respectively, 6h and 42min and 8h and 19min, both less than the recommended nocturnal sleep time. Maternal security was positively correlated with maternal state anxiety scores (rh=266, p=0.009) and negatively correlated with infant sleep latency (rh= -0.30. P=0.003). Baby sleep time was positively correlated with maternal sleep time. (rh 0.46, p<0.001). Conclusion: The more secure the mothers considered themselves, the higher the anxiety scores and the shorter the baby's sleep latency. Also, the longer the baby sleeps, the longer the mother sleeps. Thus, interventions are needed to promote the quality and efficiency of sleep for both mother and baby.

Keywords: sleep, anxiety, infant, mother-child relations

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Authors: Milu T. Cherian, Sergio C. Chai, Morgan A. Casal, Taosheng Chen

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This study aims to use CINPA1, a recently discovered small-molecule inhibitor of the xenobiotic receptor CAR (constitutive androstane receptor) for understanding the binding modes of CAR and to guide CAR-mediated gene expression profiling studies in human primary hepatocytes. CAR and PXR are xenobiotic sensors that respond to drugs and endobiotics by modulating the expression of metabolic genes that enhance detoxification and elimination. Elevated levels of drug metabolizing enzymes and efflux transporters resulting from CAR activation promote the elimination of chemotherapeutic agents leading to reduced therapeutic effectiveness. Multidrug resistance in tumors after chemotherapy could be associated with errant CAR activity, as shown in the case of neuroblastoma. CAR inhibitors used in combination with existing chemotherapeutics could be utilized to attenuate multidrug resistance and resensitize chemo-resistant cancer cells. CAR and PXR have many overlapping modulating ligands as well as many overlapping target genes which confounded attempts to understand and regulate receptor-specific activity. Through a directed screening approach we previously identified a new CAR inhibitor, CINPA1, which is novel in its ability to inhibit CAR function without activating PXR. The cellular mechanisms by which CINPA1 inhibits CAR function were also extensively examined along with its pharmacokinetic properties. CINPA1 binding was shown to change CAR-coregulator interactions as well as modify CAR recruitment at DNA response elements of regulated genes. CINPA1 was shown to be broken down in the liver to form two, mostly inactive, metabolites. The structure-activity differences of CINPA1 and its metabolites were used to guide computational modeling using the CAR-LBD structure. To rationalize how ligand binding may lead to different CAR pharmacology, an analysis of the docked poses of human CAR bound to CITCO (a CAR activator) vs. CINPA1 or the metabolites was conducted. From our modeling, strong hydrogen bonding of CINPA1 with N165 and H203 in the CAR-LBD was predicted. These residues were validated to be important for CINPA1 binding using single amino-acid CAR mutants in a CAR-mediated functional reporter assay. Also predicted were residues making key hydrophobic interactions with CINPA1 but not the inactive metabolites. Some of these hydrophobic amino acids were also identified and additionally, the differential coregulator interactions of these mutants were determined in mammalian two-hybrid systems. CINPA1 represents an excellent starting point for future optimization into highly relevant probe molecules to study the function of the CAR receptor in normal- and pathophysiology, and possible development of therapeutics (for e.g. use for resensitizing chemoresistant neuroblastoma cells).

Keywords: antagonist, chemoresistance, constitutive androstane receptor (CAR), multi-drug resistance, structure activity relationship (SAR), xenobiotic resistance

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Authors: John Zacharias, Bin Wang

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Travel comfort is increasingly seen as crucial to effecting the switch from private motorized modes to public transit. Surveys suggest that travel comfort is closely related to perceived crowding, that may involve lack of available seating, difficulty entering and exiting, jostling and other physical contacts with strangers. As found in studies on environmental stress, other factors may moderate perceptions of crowding–in this case, we hypothesize that the ambient environment may play a significant role. Travel comfort was measured by applying a structured survey to randomly selected passengers (n=369) on 3 lines of the Beijing metro on workdays. Respondents were standing with all seats occupied and with car occupancy at 14 levels. A second research assistant filmed the metro car while passengers were interviewed, to obtain the total number of passengers. Metro lines 4, 6 and 10 were selected that travel through the central city north-south, east-west and circumferentially. Respondents evaluated the following factors: crowding, noise, smell, air quality, temperature, illumination, vibration and perceived safety as they experienced them at the time of interview, and then were asked to rank these 8 factors according to their importance for their travel comfort. Evaluations were semantic differentials on a 7-point scale from highly unsatisfactory (-3) to highly satisfactory (+3). The control variables included age, sex, annual income and trip purpose. Crowding was assessed most negatively, with 41% of the scores between -3 and -2. Noise and air quality were also assessed negatively, with two-thirds of the evaluations below 0. Illumination was assessed most positively, followed by crime, vibration and temperature, all scoring at indifference (0) or slightly positive. Perception of crowding was linearly and positively related to the number of passengers in the car. Linear regression tested the impact of ambient environmental factors on perception of crowding. Noise intensity accounted for more than the actual number of individuals in the car in the perception of crowding, with smell also contributing. Other variables do not interact with the crowding variable although the evaluations are distinct. In all, only one-third of the perception of crowding (R2=.154) is explained by the number of people, with the other ambient environmental variables accounting for two-thirds of the variance (R2=.316). However, when ranking the factors by their importance to travel comfort, perceived crowding made up 69% of the first rank, followed by noise at 11%. At rank 2, smell dominates (25%), followed by noise and air quality (17%). Commuting to work induces significantly lower evaluations of travel comfort with shopping the most positive. Clearly, travel comfort is particularly important to commuters. Moreover, their perception of crowding while travelling on metro is highly conditioned by the ambient environment in the metro car. Focussing attention on the ambient environmental conditions of the metro is an effective way to address the primary concerns of travellers with overcrowding. In general, the strongly held opinions on travel comfort require more attention in the effort to induce ridership in public transit.

Keywords: ambient environment, mass rail transit, public transit, travel comfort

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Authors: Elena Kokkoni, Prasanna Kannappan, Ashkan Zehfroosh, Effrosyni Mavroudi, Kristina Strother-Garcia, James C. Galloway, Jeffrey Heinz, Rene Vidal, Herbert G. Tanner

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Early immobility affects the motor, cognitive, and social development. Current pediatric rehabilitation lacks the technology that will provide the dosage needed to promote mobility for young children at risk. The addition of socially assistive robots in early interventions may help increase the mobility dosage. The aim of this study is to examine the feasibility of an early intervention paradigm where non-walking infants experience independent mobility while socially interacting with robots. A dynamic environment is developed where both the child and the robot interact and learn from each other. The environment involves: 1) a range of physical activities that are goal-oriented, age-appropriate, and ability-matched for the child to perform, 2) the automatic functions that perceive the child’s actions through novel activity recognition algorithms, and decide appropriate actions for the robot, and 3) a networked visual data acquisition system that enables real-time assessment and provides the means to connect child behavior with robot decision-making in real-time. The environment was tested by bringing a two-year old boy with Down syndrome for eight sessions. The child presented delays throughout his motor development with the current being on the acquisition of walking. During the sessions, the child performed physical activities that required complex motor actions (e.g. climbing an inclined platform and/or staircase). During these activities, a (wheeled or humanoid) robot was either performing the action or was at its end point 'signaling' for interaction. From these sessions, information was gathered to develop algorithms to automate the perception of activities which the robot bases its actions on. A Markov Decision Process (MDP) is used to model the intentions of the child. A 'smoothing' technique is used to help identify the model’s parameters which are a critical step when dealing with small data sets such in this paradigm. The child engaged in all activities and socially interacted with the robot across sessions. With time, the child’s mobility was increased, and the frequency and duration of complex and independent motor actions were also increased (e.g. taking independent steps). Simulation results on the combination of the MDP and smoothing support the use of this model in human-robot interaction. Smoothing facilitates learning MDP parameters from small data sets. This paradigm is feasible and provides an insight on how social interaction may elicit mobility actions suggesting a new early intervention paradigm for very young children with motor disabilities. Acknowledgment: This work has been supported by NIH under grant #5R01HD87133.

Keywords: activity recognition, human-robot interaction, machine learning, pediatric rehabilitation

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Authors: Igor Faulmann, Arnaud Saj, Roland Maurer

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Spatial cognition consists in a plethora of high level cognitive abilities: among them, the ability to learn and to navigate in large scale environments is probably one of the most complex skills. Navigation is thought to rely on the ability to read a cognitive map, defined as an allocentric representation of ones environment. Those representations are of course intimately related to the two geometrical primitives of the environment: distance and direction. Also, many recent studies point to a predominant hippocampal and para-hippocampal role in spatial cognition, as well as in the more specific cluster of navigational skills. In a previous study in humans, we used a newly validated test assessing cognitive map processing by evaluating the ability to judge relative distances and directions: the CMRT (Cognitive Map Recall Test). This study identified in topographically disorientated patients (1) behavioral differences between the evaluation of distances and of directions, and (2) distinct causality patterns assessed via VLSM (i.e., distinct cerebral lesions cause distinct response patterns depending on the modality (distance vs direction questions). Thus, we hypothesized that: (1) if the CMRT really taps into the same resources as real navigation, there would be hippocampal, parahippocampal, and parietal activation, and (2) there exists underlying neuroanatomical and functional differences between the processing of this two modalities. Aiming toward a better understanding of the neuroanatomical correlates of the CMRT in humans, and more generally toward a better understanding of how the brain processes the cognitive map, we adapted the CMRT as an fMRI procedure. 23 healthy subjects (11 women, 12 men), all living in Geneva for at least 2 years, underwent the CMRT in fMRI. Results show, for distance and direction taken together, than the most active brain regions are the parietal, frontal and cerebellar parts. Additionally, and as expected, patterns of brain activation differ when comparing the two modalities. Furthermore, distance processing seems to rely more on parietal regions (compared to other brain regions in the same modality and also to direction). It is interesting to notice that no significant activity was observed in the hippocampal or parahippocampal areas. Direction processing seems to tap more into frontal and cerebellar brain regions (compared to other brain regions in the same modality and also to distance). Significant hippocampal and parahippocampal activity has been shown only in this modality. This results demonstrated a complex interaction of structures which are compatible with response patterns observed in other navigational tasks, thus showing that the CMRT taps at least partially into the same brain resources as real navigation. Additionally, differences between the processing of distances and directions leads to the conclusion that the human brain processes each modality distinctly. Further research should focus on the dynamics of this processing, allowing a clearer understanding between the two sub-processes.

Keywords: cognitive map, navigation, fMRI, spatial cognition

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Authors: Prince Kumar, Shamseer Kulangara Kandi, Diwan S. Rawat, Kasturi Mukhopadhyay

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Staphylococcus aureus is the most pathogenic of all staphylococci, a major cause of nosocomial infections, and known for acquiring resistance towards various commonly used antibiotics. Due to the widespread use of synthetic drugs, clinicians are now facing a serious threat in healthcare. The increasing resistance in staphylococci has created a need for alternatives to these synthetic drugs. One of the alternatives is a natural plant-based medicine for both disease prevention as well as the treatment of chronic diseases. Among such natural compounds, curcumin is one of the most studied molecules and has been an integral part of traditional medicines and Ayurveda from ancient times. It is a natural polyphenolic compound with diverse pharmacological effects, including anti-inflammatory, antioxidant, anti-cancerous and antibacterial activities. In spite of its efficacy and potential, curcumin has not been approved as a therapeutic agent yet, because of its low solubility, low bioavailability, and rapid metabolism in vivo. The presence of central β-diketone moiety in curcumin is responsible for its rapid metabolism. To overcome this, in the present study, curcuminoids were designed by modifying the central β-diketone moiety of curcumin into mono carbonyl moiety and their antibacterial potency against S. aureus ATCC 29213 was determined. Further, the mode of action and hemolytic activity of the most potent curcuminoids were studied. Minimum inhibitory concentration (MIC) and in vitro killing kinetics were used to study the antibacterial activity of the designed curcuminoids. For hemolytic assay, mouse Red blood cells were incubated with curcuminoids and hemoglobin release was measured spectrophotometrically. The mode of action of curcuminoids was analysed by membrane depolarization assay using membrane potential sensitive dye 3,3’-dipropylthiacarbocyanine iodide (DiSC3(5)) through spectrofluorimetry and membrane permeabilization assay using calcein-AM through flow cytometry. Antibacterial screening of the designed library (61 curcuminoids) revealed excellent in vitro potency of six compounds against S. aureus (MIC 8 to 32 µg/ml). Moreover, these six compounds were found to be non-hemolytic up to 225 µg/ml that is much higher than their corresponding MIC values. The in vitro killing kinetics data showed five of these lead compounds to be bactericidal causing >3 log reduction in the viable cell count within 4 hrs at 5 × MIC while the sixth compound was found to be bacteriostatic. Depolarization assay revealed that all the six curcuminoids caused depolarization in their corresponding MIC range. Further, the membrane permeabilization assay showed that all the six curcuminoids caused permeabilization at 5 × MIC in 2 hrs. This membrane depolarization and permeabilization caused by curcuminoids found to be in correlation with their corresponding killing efficacy. Both these assays point out that membrane perturbations might be a primary mode of action for these curcuminoids. Overall, the present study leads us six water soluble, non-hemolytic, membrane-active curcuminoids and provided an impetus for further research on therapeutic use of these lead curcuminoids against S. aureus.

Keywords: antibacterial, curcumin, minimum inhibitory concentration , Staphylococcus aureus

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Authors: W. Baumgartner, M. Welti, N. Hild, S. C. Hess, W. J. Stark, G. Meier Bürgisser, P. Giovanoli, J. Buschmann

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Perfusion bioreactors are used to solve problems in tissue engineering in terms of sufficient nutrient and oxygen supply. Such problems especially occur in critical size grafts because vascularization is often too slow after implantation ending up in necrotic cores. Biominerizable and biocompatible nanocomposite materials are attractive and suitable scaffold materials for bone tissue engineering because they offer mineral components in organic carriers – mimicking natural bone tissue. In addition, human adipose derived stem cells (ASCs) can potentially be used to increase bone healing as they are capable of differentiating towards osteoblasts or endothelial cells among others. In the present study, electrospun nanocomposite disks of poly-lactic-co-glycolic acid and amorphous calcium phosphate nanoparticles (PLGA/a-CaP) were seeded with human ASCs and eight disks were stacked in a bioreactor running with normal culture medium (no differentiation supplements). Under continuous perfusion and uniaxial cyclic compression, load-displacement curves as a function of time were assessed. Stiffness and energy dissipation were recorded. Moreover, stem cell densities in the layers of the piled scaffold were determined as well as their morphologies and differentiation status (endothelial cell differentiation, chondrogenesis and osteogenesis). While the stiffness of the cell free constructs increased over time caused by the transformation of the a-CaP nanoparticles into flake-like apatite, ASC-seeded constructs showed a constant stiffness. Stem cell density gradients were histologically determined with a linear increase in the flow direction from the bottom to the top of the 3.5 mm high pile (r2 > 0.95). Cell morphology was influenced by the flow rate, with stem cells getting more roundish at higher flow rates. Less than 1 % osteogenesis was found upon osteopontin immunostaining at the end of the experiment (9 days), while no endothelial cell differentiation and no chondrogenesis was triggered under these conditions. All ASCs had mainly remained in their original pluripotent status within this time frame. In summary, we have fabricated a critical size bone graft based on a biominerizable bone-biomimetic nanocomposite with preserved stiffness when seeded with human ASCs. The special feature of this bone graft was that ASC densities inside the piled construct varied with a linear gradient, which is a good starting point for tissue engineering interfaces such as bone-cartilage where the bone tissue is cell rich while the cartilage exhibits low cell densities. As such, this tissue-engineered graft may act as a bone-cartilage interface after the corresponding differentiation of the ASCs.

Keywords: bioreactor, bone, cartilage, nanocomposite, stem cell gradient

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Authors: Ana Flavia Belchior De Andrade

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Forensic laboratories all over the world face a great challenge to overcame waiting time and backlog in many different areas. Many aspects contribute to this situation, such as an increase in drug complexity, increment in the number of exams requested and cuts in funding limiting laboratories hiring capacity. Altogether, those facts pose an essential challenge for forensic chemistry laboratories to keep both quality and time of response within an acceptable period. In this paper we will analyze how the backlog affects test results and, in the end, the whole judicial system. In this study data from marijuana samples seized by the Federal District Civil Police in Brazil between the years 2013 and 2017 were tabulated and the results analyzed and discussed. In the last five years, the number of petitioned exams increased from 822 in February 2013 to 1358 in March 2018, representing an increase of 32% in 5 years, a rise of more than 6% per year. Meanwhile, our data shows that the number of performed exams did not grow at the same rate. Product numbers are stationed as using the actual technology scenario and analyses routine the laboratory is running in full capacity. Marijuana detection is the most prevalence exam required, representing almost 70% of all exams. In this study, data from 7,110 (seven thousand one hundred and ten) marijuana samples were analyzed. Regarding waiting time, most of the exams were performed not later than 60 days after receipt (77%). Although some samples waited up to 30 months before being examined (0,65%). When marijuana´s exam is delayed we notice the enlargement of inconclusive results using thin-layer chromatography (TLC). Our data shows that if a marijuana sample is stored for more than 18 months, inconclusive results rise from 2% to 7% and when if storage exceeds 30 months, inconclusive rates increase to 13%. This is probably because Cannabis plants and preparations undergo oxidation under storage resulting in a decrease in the content of Δ9-tetrahydrocannabinol ( Δ9-THC). An inconclusive result triggers other procedures that require at least two more working hours of our analysts (e.g., GC/MS analysis) and the report would be delayed at least one day. Those new procedures increase considerably the running cost of a forensic drug laboratory especially when the backlog is significant as inconclusive results tend to increase with waiting time. Financial aspects are not the only ones to be observed regarding backlog cases; there are also social issues as legal procedures can be delayed and prosecution of serious crimes can be unsuccessful. Delays may slow investigations and endanger public safety by giving criminals more time on the street to re-offend. This situation also implies a considerable cost to society as at some point, if the exam takes a long time to be performed, an inconclusive can turn into a negative result and a criminal can be absolved by flawed expert evidence.

Keywords: backlog, forensic laboratory, quality management, accreditation

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Authors: Hugo Lefeuvre, Jerôme Donnard, Michael Descostes, Sophie Billon, Samuel Duval, Tugdual Oger, Herve Toubon, Paul Sardini

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Spectroscopic autoradiography is a method of interest for geological sample analysis. Indeed, researchers may face different issues such as radioelement identification and quantification in the field of environmental studies. Imaging gaseous ionization detectors find their place in geosciences for conducting specific measurements of radioactivity to improve the monitoring of natural processes using naturally-occurring radioactive tracers, but also for the nuclear industry linked to the mining sector. In geological samples, the location and identification of the radioactive-bearing minerals at the thin-section scale remains a major challenge as the detection limit of the usual elementary microprobe techniques is far higher than the concentration of most of the natural radioactive decay products. The spatial distribution of each decay product in the case of uranium in a geomaterial is interesting for relating radionuclides concentration to the mineralogy. The present study aims to provide spectroscopic autoradiography analysis method for measuring the initial energy of alpha particles with a parallel ionization multiplier gaseous detector. The analysis method has been developed thanks to Geant4 modelling of the detector. The track of alpha particles recorded in the gas detector allow the simultaneous measurement of the initial point of emission and the reconstruction of the initial particle energy by a selection based on the linear energy distribution. This spectroscopic autoradiography method was successfully used to reproduce the alpha spectra from a 238U decay chain on a geological sample at the thin-section scale. The characteristics of this measurement are an energy spectrum resolution of 17.2% (FWHM) at 4647 keV and a spatial resolution of at least 50 µm. Even if the efficiency of energy spectrum reconstruction is low (4.4%) compared to the efficiency of a simple autoradiograph (50%), this novel measurement approach offers the opportunity to select areas on an autoradiograph to perform an energy spectrum analysis within that area. This opens up possibilities for the detailed analysis of heterogeneous geological samples containing natural alpha emitters such as uranium-238 and radium-226. This measurement will allow the study of the spatial distribution of uranium and its descendants in geo-materials by coupling scanning electron microscope characterizations. The direct application of this dual modality (energy-position) of analysis will be the subject of future developments. The measurement of the radioactive equilibrium state of heterogeneous geological structures, and the quantitative mapping of 226Ra radioactivity are now being actively studied.

Keywords: alpha spectroscopy, digital autoradiography, mining activities, natural decay products

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Authors: Nahid Parween Anwar, Sadia Muzaffar Bhutta, Takbir Ali

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Mentoring is a structured activity which is designed to facilitate engagement between mentor and mentee to enhance mentee’s professional capability as an effective teacher. Both mentor and mentee are important elements of the ‘mentoring equation’ and play important roles in nourishing this dynamic, collaborative and reciprocal relationship. Cluster-Based Mentoring Programme (CBMP) provides an indigenous example of a project which focused on development of primary school teachers in selected clusters with a particular focus on their classroom practice. A study was designed to examine the efficacy of CBMP as part of Strengthening Teacher Education in Pakistan (STEP) project. This paper presents results of one of the components of this study. As part of the larger study, a cross-sectional survey was employed to explore nature and patterns of mentoring process from mentees’ perspectives in the selected districts of Sindh and Balochistan. This paper focuses on the results of the study related to the question: What are mentees’ perceptions of their mentors’ support for enhancing their classroom practice during mentoring process? Data were collected from mentees (n=1148) using a 5-point scale -‘Mentoring for Effective Primary Teaching’ (MEPT). MEPT focuses on seven factors of mentoring: personal attributes, pedagogical knowledge, modelling, feedback, system requirement, development and use of material, and gender equality. Data were analysed using SPSS 20. Mentees perceptions of mentoring practice of their mentors were summarized using mean and standard deviation. Results showed that mean scale scores on mentees’ perceptions of their mentors’ practices fell between 3.58 (system requirement) and 4.55 (personal attributes). Mentees’ perceives personal attribute of the mentor as the most significant factor (M=4.55) towards streamlining mentoring process by building good relationship between mentor and mentees. Furthermore, mentees have shared positive views about their mentors efforts towards promoting gender impartiality (M=4.54) during workshop and follow up visit. Contrary to this, mentees felt that more could have been done by their mentors in sharing knowledge about system requirement (e.g. school policies, national curriculum). Furthermore, some of the aspects in high scoring factors were highlighted by the mentees as areas for further improvement (e.g. assistance in timetabling, written feedback, encouragement to develop learning corners). Mentees’ perceptions of their mentors’ practices may assist in determining mentoring needs. The results may prove useful for the professional development programme for the mentors and mentees for specific mentoring programme in order to enhance practices in primary classrooms in Pakistan. Results would contribute into the body of much-needed knowledge from developing context.

Keywords: cluster-based mentoring programme, mentoring for effective primary teaching (MEPT), professional development, survey

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Authors: Akbar Gharbali, Ali Abbasian Ardekani, Afshin Mohammadi

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Introduction: Thyroid nodules have an incidence of 33-68% in the general population. More than 5-15% of these nodules are malignant. Early detection and treatment of thyroid nodules increase the cure rate and provide optimal treatment. Between the medical imaging methods, Ultrasound is the chosen imaging technique for assessment of thyroid nodules. The confirming of the diagnosis usually demands repeated fine-needle aspiration biopsy (FNAB). So, current management has morbidity and non-zero mortality. Objective: To explore diagnostic potential of automatic texture analysis (TA) methods in differentiation benign and malignant thyroid nodules by ultrasound imaging in order to help for reliable diagnosis and monitoring of the thyroid nodules in their early stages with no need biopsy. Material and Methods: The thyroid US image database consists of 70 patients (26 benign and 44 malignant) which were reported by Radiologist and proven by the biopsy. Two slices per patient were loaded in Mazda Software version 4.6 for automatic texture analysis. Regions of interests (ROIs) were defined within the abnormal part of the thyroid nodules ultrasound images. Gray levels within an ROI normalized according to three normalization schemes: N1: default or original gray levels, N2: +/- 3 Sigma or dynamic intensity limited to µ+/- 3σ, and N3: present intensity limited to 1% - 99%. Up to 270 multiscale texture features parameters per ROIs per each normalization schemes were computed from well-known statistical methods employed in Mazda software. From the statistical point of view, all calculated texture features parameters are not useful for texture analysis. So, the features based on maximum Fisher coefficient and the minimum probability of classification error and average correlation coefficients (POE+ACC) eliminated to 10 best and most effective features per normalization schemes. We analyze this feature under two standardization states (standard (S) and non-standard (NS)) with Principle Component Analysis (PCA), Linear Discriminant Analysis (LDA) and Non-Linear Discriminant Analysis (NDA). The 1NN classifier was performed to distinguish between benign and malignant tumors. The confusion matrix and Receiver operating characteristic (ROC) curve analysis were used for the formulation of more reliable criteria of the performance of employed texture analysis methods. Results: The results demonstrated the influence of the normalization schemes and reduction methods on the effectiveness of the obtained features as a descriptor on discrimination power and classification results. The selected subset features under 1%-99% normalization, POE+ACC reduction and NDA texture analysis yielded a high discrimination performance with the area under the ROC curve (Az) of 0.9722, in distinguishing Benign from Malignant Thyroid Nodules which correspond to sensitivity of 94.45%, specificity of 100%, and accuracy of 97.14%. Conclusions: Our results indicate computer-aided diagnosis is a reliable method, and can provide useful information to help radiologists in the detection and classification of benign and malignant thyroid nodules.

Keywords: ultrasound imaging, thyroid nodules, computer aided diagnosis, texture analysis, PCA, LDA, NDA

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Authors: Kim Anema, Matthias Max, Chris Zevenbergen

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For any flood risk manager the 'safety paradox' has to be a familiar concept: low probability leads to a sense of safety, which leads to more investments in the area, which leads to higher potential consequences: keeping the aggregated risk (probability*consequences) at the same level. Therefore, it is important to mitigate potential consequences apart from probability. However, when the (perceived) probability is so low that there is no recognizable trend for society to adapt to, addressing the potential consequences will always be the lagging point on the agenda. Preparedness programs fail because of lack of interest and urgency, policy makers are distracted by their day to day business and there's always a more urgent issue to spend the taxpayer's money on. The leading question in this study was how to address the social consequences of flooding in a context of (perceived) low probability. Disruptions of everyday urban life, large or small, can be caused by a variety of (un)expected things - of which flooding is only one possibility. Variability like this is typically addressed with resilience - and we used the concept of Community Resilience as the framework for this study. Drawing on face to face interviews, an extensive questionnaire and publicly available statistical data we explored the 'whole society response' to two recent urban flood events; the Brisbane Floods (AUS) in 2011 and the Dresden Floods (GE) in 2013. In Brisbane, we studied how the societal impacts of the floods were counteracted by both authorities and the public, and in Dresden we were able to validate our findings. A large part of the reactions, both public as institutional, to these two urban flood events were not fuelled by preparedness or proper planning. Instead, more important success factors in counteracting social impacts like demographic changes in neighborhoods and (non-)economic losses were dynamics like community action, flexibility and creativity from authorities, leadership, informal connections and a shared narrative. These proved to be the determining factors for the quality and speed of recovery in both cities. The resilience of the community in Brisbane was good, due to (i) the approachability of (local) authorities, (ii) a big group of ‘secondary victims’ and (iii) clear leadership. All three of these elements were amplified by the use of social media and/ or web 2.0 by both the communities and the authorities involved. The numerous contacts and social connections made through the web were fast, need driven and, in their own way, orderly. Similarly in Dresden large groups of 'unprepared', ad hoc organized citizens managed to work together with authorities in a way that was effective and speeded up recovery. The concept of community resilience is better fitted than 'social adaptation' to deal with the potential consequences of an (im)probable flood. Community resilience is built on capacities and dynamics that are part of everyday life and which can be invested in pre-event to minimize the social impact of urban flooding. Investing in these might even have beneficial trade-offs in other policy fields.

Keywords: community resilience, disaster response, social consequences, preparedness

Procedia PDF Downloads 353

Authors: Ahlad Neti, Elisa Arch, Martha Hall

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Studies have shown that individuals who use Ankle-Foot-Orthoses (AFOs) have a high level of dissatisfaction regarding their current AFOs. Studies point to the focus on technical design with little attention given to the user perspective as a source of AFO designs that leave users dissatisfied. To design a new AFO that satisfies users and thereby improves their quality of life, the reasons for their dissatisfaction and their wants and needs for an improved AFO design must be identified. There has been little research into the user perspective on AFO use and desired improvements, so the relationship between AFO design and satisfaction in daily use must be assessed to develop appropriate metrics and constraints prior to designing a novel AFO. To assess the user perspective on AFO design, structured interviews were conducted with 7 individuals (average age of 64.29±8.81 years) who use AFOs. All interviews were transcribed and coded to identify common themes using Grounded Theory Method in NVivo 12. Qualitative analysis of these results identified sources of user dissatisfaction such as heaviness, bulk, and uncomfortable material and overall needs and wants for an AFO. Beyond the user perspective, certain objective factors must be considered in the construction of metrics and constraints to ensure that the AFO fulfills its medical purpose. These more objective metrics are rooted in a common medical device market and technical standards. Given the large body of research concerning these standards, these objective metrics and constraints were derived through a literature review. Through these two methods, a comprehensive list of metrics and constraints accounting for both the user perspective on AFO design and the AFO’s medical purpose was compiled. These metrics and constraints will establish the framework for designing a new AFO that carries out its medical purpose while also improving the user experience. The metrics can be categorized into several overarching areas for AFO improvement. Categories of user perspective related metrics include comfort, discreteness, aesthetics, ease of use, and compatibility with clothing. Categories of medical purpose related metrics include biomechanical functionality, durability, and affordability. These metrics were used to guide an iterative prototyping process. Six concepts were ideated and compared using system-level analysis. From these six concepts, two concepts – the piano wire model and the segmented model – were selected to move forward into prototyping. Evaluation of non-functional prototypes of the piano wire and segmented models determined that the piano wire model better fulfilled the metrics by offering increased stability, longer durability, fewer points for failure, and a strong enough core component to allow a sock to cover over the AFO while maintaining the overall structure. As such, the piano wire AFO has moved forward into the functional prototyping phase, and healthy subject testing is being designed and recruited to conduct design validation and verification.

Keywords: ankle-foot orthotic, assistive technology, human centered design, medical devices

Procedia PDF Downloads 158

Authors: J. van Vuuren, D. J. van Vuuren, R. Muigai

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In recent times, South Africa has experienced extensive droughts that created the need for reliable small water reservoirs. These reservoirs have comparatively quick fabrication and installation times compared to market alternatives. An elevated water tank has inherent potential energy, resulting in that no additional water pumps are required to sustain water pressure at the outlet point – thus ensuring that, without electricity, a water source is available. The initial construction formwork and the complex geometric shape of concrete towers that requires casting can become time-consuming, rendering steel towers preferable. Reinforced concrete foundations, cast in advance, are required to be of sufficient strength. Thereafter, the prefabricated steel supporting structure and tank, which consist of steel panels, can be assembled and erected on site within a couple of days. Due to the time effectiveness of this system, it has become a popular solution to aid drought-stricken areas. These sites are normally in rural, schools or farmland areas. As these tanks can contain up to 2000kL (approximately 19.62MN) of water, combined with supporting lattice steel structures ranging between 5m and 30m in height, failure of one of the supporting members will result in system failure. Thus, there is a need to gain a comprehensive understanding of the operation conditions because of wind loadings on both the tank and the supporting structure. The aim of the research is to investigate the relationship between the theoretical wind loading on a lattice steel tower in combination with an elevated sectional steel tank, and the current wind loading codes, as applicable to South Africa. The research compares the respective design parameters (both theoretical and wind loading codes) whereby FEA analyses are conducted on the various design solutions. The currently available wind loading codes are not sufficient to design slender cantilever latticed steel towers that support elevated water storage tanks. Numerous factors in the design codes are not comprehensively considered when designing the system as these codes are dependent on various assumptions. Factors that require investigation for the study are; the wind loading angle to the face of the structure that will result in maximum load; the internal structural effects on models with different bracing patterns; the loading influence of the aspect ratio of the tank; and the clearance height of the tank on the structural members. Wind loads, as the variable that results in the highest failure rate of cantilevered lattice steel tower structures, require greater understanding. This study aims to contribute towards the design process of elevated steel tanks with lattice tower supporting structures.

Keywords: aspect ratio, bracing patterns, clearance height, elevated steel tanks, lattice steel tower, wind loads

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Authors: Pangkaj Kumar Mahanta, Md. Rafizul Islam

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The rapid growth of the population causes a substantial amount of increase in household waste all over the world. Waste management is becoming one of the most challenging phenomena in the present day. The most environmentally friendly final disposal process of waste is sanitary landfilling, which is practiced in most developing countries. However, in Southeast Asia, most of the final disposal point is an open dump site. Due to the ignominy of proper management of waste and monitoring, the surrounding environment gets polluted more by the open dump site in comparison with a sanitary landfill. Khulna is 3rd largest metropolitan city in Bangladesh, having a population of around 1.5 million and producing approximately 450 tons per day of Municipal Solid Waste. The Municipal solid waste of Khulna city is disposed of in Rajbandh open dump site. The surrounding air is being polluted by the gas produced in the open dump site. Also, the open dump site produces leachate, which contains various heavy metals like Cadmium (Cd), Chromium (Cr), Lead (Pb), Manganese (Mn), Mercury (Hg), Strontium (Sr), etc. Leachate pollutes the soil as well as the groundwater of the open dump site and also the surrounding area through seepage. Moreover, during the rainy season, the surface water is polluted by leachate runoff. Also, the plastic waste flowing out from the open dump site through various drivers pollutes the nearby environment. The health risk assessment associated with heavy metals was carried out by computing the chronic daily intake (CDI), hazard quotient (HQ), and hazard index (HI) via different exposure pathways following the USEPA guidelines. For ecological risk, potential contamination index (Cp), Contamination factor (CF), contamination load index (PLI), numerical integrated contamination factor (NICF), enrichment factor (EF), ecological risk index (ER), and potential ecological risk index (PERI) were computed. The health risk and ecological risk assessment results reveal that some heavy metals possess strong health and ecological risk. In addition, the child faces higher harmful health risks from several heavy metals than the adult for all the exposure pathways and media. The conversion of an open dump site into a sanitary landfill and a proper management system can reduce the problems associated with an open dump site. In the sanitary landfill, the produced gas will be managed properly to save the surrounding atmosphere from being polluted. The seepage of leachate can be minimized by installing a compacted clay layer (CCL) as a baseline and leachate collection in a sanitary landfill to save the underlying soil layer and surrounding water bodies from leachate. Another important component of a sanitary landfill is the conversion of plastic waste to energy will minimize the plastic pollution in the landfill area and also the surrounding soil and water bodies. Also, in the sanitary landfill, the bio-waste can be used to make compost to reduce the volume of bio-waste and proper utilization of the landfill area.

Keywords: ecological risk, health risk, open dump site, sanitary landfill

Procedia PDF Downloads 195

Authors: L. Asaro, M. Gratton, S. Seghar, N. Poirot, N. Ait Hocine

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Rubber waste disposal is an environmental problem. Particularly, many researches are centered in the management of discarded tires. In spite of all different ways of handling used tires, the most common is to deposit them in a landfill, creating a stock of tires. These stocks can cause fire danger and provide ambient for rodents, mosquitoes and other pests, causing health hazards and environmental problems. Because of the three-dimensional structure of the rubbers and their specific composition that include several additives, their recycling is a current technological challenge. The technique which can break down the crosslink bonds in the rubber is called devulcanization. Strictly, devulcanization can be defined as a process where poly-, di-, and mono-sulfidic bonds, formed during vulcanization, are totally or partially broken. In the recent years, super critical carbon dioxide (scCO₂) was proposed as a green devulcanization atmosphere. This is because it is chemically inactive, nontoxic, nonflammable and inexpensive. Its critical point can be easily reached (31.1 °C and 7.38 MPa), and residual scCO₂ in the devulcanized rubber can be easily and rapidly removed by releasing pressure. In this study thermomechanical devulcanization of ground tire rubber (GTR) was performed in a twin screw extruder under diverse operation conditions. Supercritical CO₂ was added in different quantities to promote the devulcanization. Temperature, screw speed and quantity of CO₂ were the parameters that were varied during the process. The devulcanized rubber was characterized by its devulcanization percent and crosslink density by swelling in toluene. Infrared spectroscopy (FTIR) and Gel permeation chromatography (GPC) were also done, and the results were related with the Mooney viscosity. The results showed that the crosslink density decreases as the extruder temperature and speed increases, and, as expected, the soluble fraction increase with both parameters. The Mooney viscosity of the devulcanized rubber decreases as the extruder temperature increases. The reached values were in good correlation (R= 0.96) with de the soluble fraction. In order to analyze if the devulcanization was caused by main chains or crosslink scission, the Horikx's theory was used. Results showed that all tests fall in the curve that corresponds to the sulfur bond scission, which indicates that the devulcanization has successfully happened without degradation of the rubber. In the spectra obtained by FTIR, it was observed that none of the characteristic peaks of the GTR were modified by the different devulcanization conditions. This was expected, because due to the low sulfur content (~1.4 phr) and the multiphasic composition of the GTR, it is very difficult to evaluate the devulcanization by this technique. The lowest crosslink density was reached with 1 cm³/min of CO₂, and the power consumed in that process was also near to the minimum. These results encourage us to do further analyses to better understand the effect of the different conditions on the devulcanization process. The analysis is currently extended to monophasic rubbers as ethylene propylene diene monomer rubber (EPDM) and natural rubber (NR).

Keywords: devulcanization, recycling, rubber, waste

Procedia PDF Downloads 389

Authors: Daniel Sava, Dragos Gudovan, Iulia Alexandra Gudovan, Ioana Ardelean, Maria Sonmez, Denisa Ficai, Laurentia Alexandrescu, Ecaterina Andronescu

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Graphene and graphene oxide have been intensively studied due to the very good properties, which are intrinsic to the material or come from the easy doping of those with other functional groups. Graphene and graphene oxide have known a broad band of useful applications, in electronic devices, drug delivery systems, medical devices, sensors and opto-electronics, coating materials, sorbents of different agents for environmental applications, etc. The board range of applications does not come only from the use of graphene or graphene oxide alone, or by its prior functionalization with different moieties, but also it is a building block and an important component in many composite devices, its addition coming with new functionalities on the final composite or strengthening the ones that are already existent on the parent product. An attempt to improve the mechanical properties of polyamide elastomers by compounding with graphene oxide in the parent polymer composition was attempted. The addition of the graphene oxide contributes to the properties of the final product, improving the hardness and aging resistance. Graphene oxide has a lower hardness and textile strength, and if the amount of graphene oxide in the final product is not correctly estimated, it can lead to mechanical properties which are comparable to the starting material or even worse, the graphene oxide agglomerates becoming a tearing point in the final material if the amount added is too high (in a value greater than 3% towards the parent material measured in mass percentages). Two different types of tests were done on the obtained materials, the hardness standard test and the tensile strength standard test, and they were made on the obtained materials before and after the aging process. For the aging process, an accelerated aging was used in order to simulate the effect of natural aging over a long period of time. The accelerated aging was made in extreme heat. For all materials, FT-IR spectra were recorded using FT-IR spectroscopy. From the FT-IR spectra only the bands corresponding to the polyamide were intense, while the characteristic bands for graphene oxide were very small in comparison due to the very small amounts introduced in the final composite along with the low absorptivity of the graphene backbone and limited number of functional groups. In conclusion, some compositions showed very promising results, both in tensile strength test and in hardness tests. The best ratio of graphene to elastomer was between 0.6 and 0.8%, this addition extending the life of the product. Acknowledgements: The present work was possible due to the EU-funding grant POSCCE-A2O2.2.1-2013-1, Project No. 638/12.03.2014, code SMIS-CSNR 48652. The financial contribution received from the national project ‘New nanostructured polymeric composites for centre pivot liners, centre plate and other components for the railway industry (RONERANANOSTRUCT)’, No: 18 PTE (PN-III-P2-2.1-PTE-2016-0146) is also acknowledged.

Keywords: graphene, graphene oxide, mechanical properties, dopping effect

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Authors: M. I. Tyletc, O. I. Podgornya, T. G. Shaposhnikova, S. V. Shabelnikov, A. G. Mittenberg, M. A. Daugavet

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Ascidiacea is the most numerous class of the Tunicata subtype. These chordates' distinctive feature of the anatomical structure is a tunic consisting of cellulose fibrils, protein molecules, and single cells. The mechanisms of the tunic formation are not known in detail; tunic formation could be used as the model system for studying the interaction of cells with the extracellular matrix. Our model species is the ascidian Styela rustica, which is prevalent in benthic communities of the White Sea. As previously shown, the tunic formation involves morula blood cells, which contain the major 48 kDa protein p48. P48 participation in the tunic formation was proved using antibodies against the protein. The nature of the protein and its function remains unknown. The current research aims to determine the amino acid sequence of p48, as well as to clarify its role in the tunic formation. The peptides that make up the p48 amino acid sequence were determined by mass spectrometry. A search for peptides in protein sequence databases identified sequences homologous to p48 in Styela clava, Styela plicata, and Styela canopus. Based on sequence alignment, their level of similarity was determined as 81-87%. The correspondent sequence of ascidian Styela canopus was used for further analysis. The Styela rustica p48 sequence begins with a signal peptide, which could indicate that the protein is secretory. This is consistent with experimentally obtained data: the contents of morula cells secreted in the tunic matrix. The isoelectric point of p48 is 9.77, which is consistent with the experimental results of acid electrophoresis of morula cell proteins. However, the molecular weight of the amino acid sequence of ascidian Styela canopus is 103 kDa, so p48 of Styela rustica is a shorter homolog. The search for conservative functional domains revealed the presence of two Ca-binding EGF-like domains, thrombospondin (TSP1) and tyrosinase domains. The p48 peptides determined by mass spectrometry fall into the region of the sequence corresponding to the last two domains and have amino acid substitutions as compared to Styela canopus homolog. The tyrosinase domain (pfam00264) is known to be part of the phenoloxidase enzyme, which participates in melanization processes and the immune response. The thrombospondin domain (smart00209) interacts with a wide range of proteins, and is involved in several biological processes, including coagulation, cell adhesion, modulation of intercellular and cell-matrix interactions, angiogenesis, wound healing and tissue remodeling. It can be assumed that the tyrosinase domain in p48 plays the role of the phenoloxidase enzyme, and TSP1 provides a link between the extracellular matrix and cell surface receptors, and may also be responsible for the repair of the tunic. The results obtained are consistent with experimental data on p48. The domain organization of protein suggests that p48 is an enzyme involved in the tunic tunning and is an important regulator of the organization of the extracellular matrix.

Keywords: ascidian, p48, thrombospondin, tyrosinase, tunic, tunning

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Authors: Nasser Salah Eldin Mohammed Salih Shebka

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Current problematic issues in AI fields are mainly due to those of knowledge representation conceptual theories, which in turn reflected on the entire scope of cognitive sciences. Knowledge representation methods and tools are driven from theoretical concepts regarding human scientific perception of the conception, nature, and process of knowledge acquisition, knowledge engineering and knowledge generation. And although, these theoretical conceptions were themselves driven from the study of the human knowledge representation process and related theories; some essential factors were overlooked or underestimated, thus causing critical methodological deficiencies in the conceptual theories of human knowledge and knowledge representation conceptions. The evaluation criteria of human cumulative knowledge from the perspectives of nature and theoretical aspects of knowledge representation conceptions are affected greatly by the very materialistic nature of cognitive sciences. This nature caused what we define as methodological deficiencies in the nature of theoretical aspects of knowledge representation concepts in AI. These methodological deficiencies are not confined to applications of knowledge representation theories throughout AI fields, but also exceeds to cover the scientific nature of cognitive sciences. The methodological deficiencies we investigated in our work are: - The Segregation between cognitive abilities in knowledge driven models.- Insufficiency of the two-value logic used to represent knowledge particularly on machine language level in relation to the problematic issues of semantics and meaning theories. - Deficient consideration of the parameters of (existence) and (time) in the structure of knowledge. The latter requires that we present a more detailed introduction of the manner in which the meanings of Existence and Time are to be considered in the structure of knowledge. This doesn’t imply that it’s easy to apply in structures of knowledge representation systems, but outlining a deficiency caused by the absence of such essential parameters, can be considered as an attempt to redefine knowledge representation conceptual approaches, or if proven impossible; constructs a perspective on the possibility of simulating human cognition on machines. Furthermore, a redirection of the aforementioned expressions is required in order to formulate the exact meaning under discussion. This redirection of meaning alters the role of Existence and time factors to the Frame Work Environment of knowledge structure; and therefore; knowledge representation conceptual theories. Findings of our work indicate the necessity to differentiate between two comparative concepts when addressing the relation between existence and time parameters, and between that of the structure of human knowledge. The topics presented throughout the paper can also be viewed as an evaluation criterion to determine AI’s capability to achieve its ultimate objectives. Ultimately, we argue some of the implications of our findings that suggests that; although scientific progress may have not reached its peak, or that human scientific evolution has reached a point where it’s not possible to discover evolutionary facts about the human Brain and detailed descriptions of how it represents knowledge, but it simply implies that; unless these methodological deficiencies are properly addressed; the future of AI’s qualitative progress remains questionable.

Keywords: cognitive sciences, knowledge representation, ontological reasoning, temporal logic

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Authors: Aisha Alshdefat, Lina Shakman

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Objective: With environmental sustainability (ES) emerging as a critical concern due to its global impact, higher education institutions play a vital role in promoting ES through curricula and campus operations. This study examines the perceptions, attitudes, and behaviors related to ES among students at Sultan Qaboos University, aiming to identify areas for improved integration of sustainability practices in higher education. Design: A descriptive cross-sectional study, conducted via an online questionnaire, examines perceptions and attitudes toward environmental sustainability among students at Sultan Qaboos University, Muscat, Oman. The survey instrument employs a 5-point Likert scale to assess six key areas: awareness, concern, attitude, willingness to participate, current behaviors, and recommendations for enhancing campus sustainability initiatives. A convenience sample of 200 students was initially targeted, with 157 students ultimately responding between September and November 2024. Eligible participants included Undergraduate and graduate students who consented after being fully informed of the study objectives and design were included, while those who withdrew or refused participation were excluded. Following ethical approval, data collection was carried out through Google Forms. SPSS Version 23 was used for descriptive and inferential analyses, including Pearson’s correlation, chi-square, and Fisher's exact test, to explore associations among key variables. Findings: Preliminary analysis indicates that 68% of participants are familiar with core environmental sustainability (ES) concepts, including the Sustainable Development Goals (SDGs), and express high concern regarding environmental issues. However, only 47% report active involvement in campus-led ES initiatives, underscoring an engagement gap. Over 70% of respondents believe that sustainability should be prioritized as a university policy, and 62% expressed willingness to participate in additional ES-related programs. Despite this interest, 58% advocated for more sustainability-focused courses in their curriculum, suggesting current offerings are insufficient. Statistical analysis revealed a significant positive correlation between ES awareness and willingness to engage in sustainable practices (p < 0.05). These findings highlight the need for expanded institutional efforts, including targeted programs and curriculum integration, to cultivate a more sustainability-centered culture among students. Conclusion: The results emphasize that while students demonstrate a strong foundational awareness of ES, greater institutional support is essential to transform this awareness into active engagement. More comprehensive integration of sustainability within academic programs and campus life could substantially enhance students’ involvement and commitment to environmental stewardship.

Keywords: environmental sustainability, higher education, students, perceptions, Sultan Qaboos University.

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Authors: Shahrzad Zolfagharnassab, Abdul Rashid Mohamed Shariff, Siti Khairunniza Bejo

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Conventional methods for nutrient soil mapping are based on laboratory tests of samples that are obtained from surveys. The time and cost involved in gathering and analyzing soil samples are the reasons that researchers use Predictive Soil Mapping (PSM). PSM can be defined as the development of a numerical or statistical model of the relationship among environmental variables and soil properties, which is then applied to a geographic database to create a predictive map. Kriging is a group of geostatistical techniques to spatially interpolate point values at an unobserved location from observations of values at nearby locations. The main problem with using kriging as an interpolator is that it is excessively data-dependent and requires a large number of closely spaced data points. Hence, there is a need to minimize the number of data points without sacrificing the accuracy of the results. In this paper, an Artificial Neural Networks (ANN) scheme was used to predict macronutrient values at un-sampled points. ANN has become a popular tool for prediction as it eliminates certain difficulties in soil property prediction, such as non-linear relationships and non-normality. Back-propagation multilayer feed-forward network structures were used to predict nitrogen, phosphorous and potassium values in the soil of the study area. A limited number of samples were used in the training, validation and testing phases of ANN (pattern reconstruction structures) to classify soil properties and the trained network was used for prediction. The soil analysis results of samples collected from the soil survey of block C of Sawah Sempadan, Tanjung Karang rice irrigation project at Selangor of Malaysia were used. Soil maps were produced by the Kriging method using 236 samples (or values) that were a combination of actual values (obtained from real samples) and virtual values (neural network predicted values). For each macronutrient element, three types of maps were generated with 118 actual and 118 virtual values, 59 actual and 177 virtual values, and 30 actual and 206 virtual values, respectively. To evaluate the performance of the proposed method, for each macronutrient element, a base map using 236 actual samples and test maps using 118, 59 and 30 actual samples respectively produced by the Kriging method. A set of parameters was defined to measure the similarity of the maps that were generated with the proposed method, termed the sample reduction method. The results show that the maps that were generated through the sample reduction method were more accurate than the corresponding base maps produced through a smaller number of real samples. For example, nitrogen maps that were produced from 118, 59 and 30 real samples have 78%, 62%, 41% similarity, respectively with the base map (236 samples) and the sample reduction method increased similarity to 87%, 77%, 71%, respectively. Hence, this method can reduce the number of real samples and substitute ANN predictive samples to achieve the specified level of accuracy.

Keywords: artificial neural network, kriging, macro nutrient, pattern recognition, precision farming, soil mapping

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Authors: Javier Carroquino, Nieves García-Casarejos, Pilar Gargallo, F. Javier García-Ramos

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The energy used in agriculture is a source of global emissions of greenhouse gases. The two main types of this energy are electricity for pumping and diesel for agricultural machinery. In order to reduce these emissions, the European project LIFE REWIND addresses the supply of this demand from renewable sources. First of all, comprehensive data on energy demand and available renewable resources have been obtained in several case studies. Secondly, a set of simulations and optimizations have been performed, in search of the best configuration and sizing, both from an economic and emission reduction point of view. For this purpose, it was used software based on genetic algorithms. Thirdly, a prototype has been designed and installed, that it is being used for the validation in a real case. Finally, throughout a year of operation, various technical and economic parameters are being measured for further analysis. The prototype is not connected to the utility grid, avoiding the cost and environmental impact of a grid extension. The system includes three kinds of photovoltaic fields. One is located on a fixed structure on the terrain. Another one is floating on an irrigation raft. The last one is mounted on a two axis solar tracker. Each has its own solar inverter. The total amount of nominal power is 44 kW. A lead acid battery with 120 kWh of capacity carries out the energy storage. Three isolated inverters support a three phase, 400 V 50 Hz micro-grid, the same characteristics of the utility grid. An advanced control subsystem has been constructed, using free hardware and software. The electricity produced feeds a set of seven pumps used for purification, elevation and pressurization of water in a drip irrigation system located in a vineyard. Since the irrigation season does not include the whole year, as well as a small oversize of the generator, there is an amount of surplus energy. With this surplus, a hydrolyser produces on site hydrogen by electrolysis of water. An off-road vehicle with fuel cell feeds on that hydrogen and carries people in the vineyard. The only emission of the process is high purity water. On the one hand, the results show the technical and economic feasibility of stand-alone renewable energy systems to feed seasonal pumping. In this way, the economic costs, the environmental impacts and the landscape impacts of grid extensions are avoided. The use of diesel gensets and their associated emissions are also avoided. On the other hand, it is shown that it is possible to replace diesel in agricultural machinery, substituting it for electricity or hydrogen of 100% renewable origin and produced on the farm itself, without any external energy input. In addition, it is expected to obtain positive effects on the rural economy and employment, which will be quantified through interviews.

Keywords: drip irrigation, greenhouse gases, hydrogen, renewable energy, vineyard

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Authors: Ling-Ling E, Lin Feng, Hong-Chen Liu, Dong-Sheng Wang, Zhanping Shi, Juncheng Wang, Wei Luo, Yan Lv

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The objective of this study was to compare the effects of the two calcium phosphate composite scaffolds on the attachment, proliferation and osteogenic differentiation of rabbit dental pulp stem cells (DPSCs). One nano-hydroxyapatite/collagen/poly (L-lactide) (nHAC/PLA), imitating the composition and the micro-structure characteristics of the natural bone, was made by Beijing Allgens Medical Science & Technology Co., Ltd. (China). The other beta-tricalcium phosphate (β-TCP), being fully interoperability globular pore structure, was provided by Shanghai Bio-lu Biomaterials Co, Ltd. (China). We compared the absorption water rate and the protein adsorption rate of two scaffolds and the characterization of DPSCs cultured on the culture plate and both scaffolds under osteogenic differentiation media (ODM) treatment. The constructs were then implanted subcutaneously into the back of severe combined immunodeficient (SCID) mice for 8 and 12 weeks to compare their bone formation capacity. The results showed that the ODM-treated DPSCs expressed osteocalcin (OCN), bone sialoprotein (BSP), type I collagen (COLI) and osteopontin (OPN) by immunofluorescence staining. Positive alkaline phosphatase (ALP) staining, calcium deposition and calcium nodules were also observed on the ODM-treated DPSCs. The nHAC/PLA had significantly higher absorption water rate and protein adsorption rate than ß-TCP. The initial attachment of DPSCs seeded onto nHAC/PLA was significantly higher than that onto ß-TCP; and the proliferation rate of the cells was significantly higher than that of ß-TCP on 1, 3 and 7 days of cell culture. DPSCs+ß-TCP had significantly higher ALP activity, calcium/phosphorus content and mineral formation than DPSCs+nHAC/PLA. When implanted into the back of SCID mice, nHAC/PLA alone had no new bone formation, newly formed mature bone and osteoid were only observed in β-TCP alone, DPSCs+nHAC/PLA and DPSCs+β-TCP, and this three groups displayed increased bone formation over the 12-week period. The percentage of total bone formation area had no difference between DPSCs+β-TCP and DPSCs+nHAC/PLA at each time point，but the percentage of mature bone formation area of DPSCs+β-TCP was significantly higher than that of DPSCs+nHAC/PLA. Our results demonstrated that the DPSCs on nHAC/PLA had a better proliferation and that the DPSCs on β-TCP had a more mineralization in vitro, much more newly formed mature bones in vivo were presented in DPSCs+β-TCP group. These findings have provided a further knowledge that scaffold architecture has a different influence on the attachment, proliferation and differentiation of cells. This study may provide insight into the clinical periodontal bone tissue repair with DPSCs+β-TCP construct.

Keywords: dental pulp stem cells, nano-hydroxyapatite/collagen/poly(L-lactide), beta-tricalcium phosphate, periodontal tissue engineering, bone regeneration

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Authors: Virginia Guillén Cañas, Miren Agurtzane Ortiz-Jauregi, Sonia Ruiz De Azua, Naiara Ozamiz

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We want to focus on relationship of the communicational skills in several key aspects of medicine. The most relevant competencies of a health professional are an adequate communication capacity, which will influence the satisfaction of professionals and patients, therapeutic compliance, conflict prevention, clinical outcomes’ improvement and efficiency of health services. We define empathy as it as Sympathy and connection to others and capability to communicate this understanding. Some outcomes favoring empathy are female gender, younger age, and specialty choice. Third gender or third sex is a concept in which allows a person not to be categorized in a dual way but as a continuous variable, giving the choice of moving along it. This point of view recognizes three or more genders. The subject of Ethics and Clinical Communication is dedicated to sensitizing students about the importance and effectiveness of a good therapeutic relationship. We are also interested in other communicational aspects related to empathy as active listening, assertivity and basic and advanced Social Skills. Objectives: 1. To facilitate the approach of the student in the Medicine Degree to the reality of the medical profession 2. Analyze interesting outcome variables in communication 3. Interactive process to detect the areas of improvement in the learning process of the Physician throughout his professional career needs. Design: A comparative study with a cross-sectional approach was conducted in successive academic year cohorts of health professional students at a public Basque university. Four communicational aspects were evaluated through these questionnaires in Basque, Spanish and English: The active listening questionnaire, the TECA empathy questionnaire, the ACDA questionnaire and the EHS questionnaire Social Skills Scale. Types of interventions for improving skills: Interpersonal skills training intervention, Empathy intervention, Writing about experiential learning, Drama through role plays, Communicational skills training, Problem-based learning, Patient interviews ´videos, Empathy-focused training, Discussion. Results: It identified the need for a cross cultural adaptation and no gender distinction. The students enjoyed all the techniques in comparison to the usual master class. There was medium participation but these participative methodologies are not so usual in the university. According to empathy, men have a greater empathic capacity to fully understand women (p < 0.05) With regard to assertiveness there have been no differences between men and women in self-assertiveness but nevertheless women are more heteroassertive than men. Conclusions: These findings suggest that educational interventions with adequate feedback can be effective in maintaining and enhancing empathy in undergraduate medical students.

Keywords: physician's communicational skills, patient satisfaction, third gender, cross cultural adaptation

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Authors: Hitesh Kshayap, Shantanu Arya, Ajay Basod, Sachin Sakhuja

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This study was undertaken to measure the overall noise levels in different locations/zones and to estimate the prevalence of Noise induced hearing loss in Hawkers & Shopkeepers in Mumbai, India. The Hearing Test developed by American Academy Of Otolaryngology, translated from English to Hindi, and validated is used as a screening tool for hearing sensitivity was employed. The tool is having 14 items. Each item is scored on a scale 0, 1, 2 and 3. The score 6 and above indicated some difficulty or definite difficulty in hearing in daily activities and low score indicated lesser difficulty or normal hearing. The subjects who scored 6 or above or having tinnitus were made to undergo hearing evaluation by Pure tone audiometer. Further, the environmental noise levels were measured from Morning to Evening at road side at different Location/Hawking zones in Mumbai city using SLM9 Agronic 8928B & K type Digital Sound Level Meter) in dB (A). The maximum noise level of 100.0 dB (A) was recorded during evening hours from Chattrapati Shivaji Terminal to Colaba with overall noise level of 79.0 dB (A). However, the minimum noise level in this area was 72.6 dB (A) at any given point of time. Further, 54.6 dB (A) was recorded as minimum noise level during 8-9 am at Sion Circle. Further, commencement of flyovers with 2-tier traffic, sky walks, increasing number of vehicular traffic at road, high rise buildings and other commercial & urbanization activities in the Mumbai city most probably have resulted in increasing the overall environmental noise levels. Trees which acted as noise absorbers have been cut owing to rapid construction. The study involved 100 participants in the age range of 18 to 40 years of age, with the mean age of 29 years (S.D. =6.49). 46 participants having tinnitus or have obtained the score of 6 were made to undergo Pure Tone Audiometry and it was found that the prevalence rate of hearing loss in hawkers & shopkeepers is 19% (10% Hawkers and 9 % Shopkeepers). The results found indicates that 29 (42.6%) out of 64 Hawkers and 17 (47.2%) out of 36 Shopkeepers who underwent PTA had no significant difference in percentage of Noise Induced Hearing loss. The study results also reveal that participants who exhibited tinnitus 19 (41.30%) out of 46 were having mild to moderate sensorineural hearing loss between 3000Hz to 6000Hz. The Pure tone Audiogram pattern revealed Hearing loss at 4000 Hz and 6000 Hz while hearing at adjacent frequencies were nearly normal. 7 hawkers and 8 shopkeepers had mild notch while 3 hawkers and 1 shopkeeper had a moderate degree of notch. It is thus inferred that tinnitus is a strong indicator for presence of hearing loss and 4/6 KHz notch is a strong marker for road/traffic/ environmental noise as an occupational hazard for hawkers and shopkeepers. Mass awareness about these occupational hazards, regular hearing check up, early intervention along with sustainable development juxtaposed with social and urban forestry can help in this regard.

Keywords: NIHL, noise, sound level meter, tinnitus

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Authors: Robert Birkholc

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One of the basic issues related to the creation of characters in media, such as literature and film, is the representation of the characters' thoughts, emotions, and perceptions. This paper is devoted to the social perspective (or the focalization) expressed in film narration. The aim of the paper is to show how social point of view of the hero –conditioned by his origin and the environment from which he comes– can be created by using non-verbal, purely audiovisual means of expression. The issue will be considered on the example of the little-known polish movie The Dancing Hawk (1977) by Grzegorz Królikiewicz, based on the novel by Julian Kawalec. The thesis of the paper is that the polish director uses a narrative figure, which is somewhat analogous to literary form of free indirect discourse. In literature, free indirect discourse is formally ‘spoken’ by the external narrator, but the narration is clearly filtered through the language and thoughts of the character. According to some scholars (such as Roy Pascal), the narrator in this form of speech does not cite the character's words, but uses his way of thinking and imitates his perspective – sometimes with a deep irony. Free indirect discourse is frequently used in Julian Kawalec’s novel. Through the linguistic stylization, the author tries to convey the socially determined perspective of a peasant who migrates to the big city after the Second World War. Grzegorz Królikiewicz expresses the same social experience by pure cinematic form in the adaptation of the book. Both Kawalec and Królikiewicz show the consequences of so-called ‘social advancement’ in Poland after 1945, when the communist party took over political power. On the example of the fate of the main character, Michał Toporny, the director presents the experience of peasants who left their villages and had to adapt to new, urban space. However, the paper is not focused on the historical topic itself, but on the audiovisual form of the movie. Although Królikiewicz doesn’t use frequently POV shots, the narration of The Dancing Hawk is filtered through the sensations of the main character, who feels uprooted and alienated in the new social space. The director captures the hero's feelings through very complex audiovisual procedures – high or low points of view (representing the ‘social position’), grotesque soundtrack, expressionist scenery, and associative editing. In this way, he manages to create the world from the perspective of a socially maladjusted and internally split subject. The Dancing Hawk is a successful attempt to adapt the subjective narration of the book to the ‘language’ of the cinema. Mieke Bal’s notion of focalization helps to describe ‘free indirect discourse’ as a transmedial figure of representing of the characters’ perceptions. However, the polysemiotic medium of the film also significantly transforms this figure of representation. The paper shows both the similarities and differences between literary and cinematic ‘free indirect discourse.’

Keywords: film and literature, free indirect discourse, social experience, subjective narration

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Authors: A. Chiker, A. Benamor, A. Haddad, Y. Hadji, M. Hadji

Abstract:

Metal matrix composites (MMCs) have been of big interest for a few decades. Their major drawback lies in their enhanced mechanical performance over unreinforced alloys. They found ground in many engineering fields, such as aeronautics, aerospace, automotive, and other structural applications. One of the most used alloys as a matrix is nickel alloys, which meet the need for high-temperature mechanical properties; some attempts have been made to develop nickel base composites reinforced by high melt point and high modulus particulates. Among the carbides used as reinforcing particulates, chromium carbide is interesting for wear applications; it is widely used as a tribological coating material in high-temperature applications requiring high wear resistance and hardness. Moreover, a set of properties make it suitable for use in MMCs, such as toughness, the good corrosion and oxidation resistance of its three polymorphs -the cubic (Cr23C6), the hexagonal (Cr7C3), and the orthorhombic (Cr3C2)-, and it’s coefficient of thermal expansion that is almost equal to that of metals. The in-situ synthesis of CrC-reinforced Ni matrix composites could be achieved by the powder metallurgy route. To ensure the in-situ reactions during the sintering process, the use of phase precursors is necessary. Recently, new precursor materials have been proposed; these materials are called MAX phases. The MAX phases are thermodynamically stable nano-laminated materials displaying unusual and sometimes unique properties. These novel phases possess Mn+1AXn chemistry, where n is 1, 2, or 3, M is an early transition metal element, A is an A-group element, and X is C or N. Herein, the pressureless sintering method is used to elaborate Ni/Cr2AlC composites. Four composites were elaborated from 5, 10, 15 and 20 wt% of Cr2AlC MAX phase precursor which fully reacted with Ni-matrix at 1100 °C sintering temperature for 4 h in argon atmosphere. XRD results showed that Cr2AlC MAX phase was totally decomposed forming chromium carbide Cr7C3, and the released Al and Cr atoms diffused in Ni matrix giving rise to γ-Ni(Al,Cr) solid solution and γ’-Ni3(Al,Cr) intermetallic. Scanning Electron Microscopy (SEM) of the elaborated samples showed the presence of nanosized Cr7C3 reinforcing particles embedded in the Ni metal matrix, which have a direct impact on the tribological properties of the composites and their hardness. All the composites exhibited higher hardness than pure Ni; whereas adding 15 wt% of Cr2AlC gives the highest hardness (1.85 GPa). Using a ball-on-disc tribometer, dry sliding tests for the elaborated composites against 100Cr6 steel ball were studied under different applied loads. The microstructures and worn surface characteristics were then analyzed using SEM and Raman spectroscopy. The results show that all the composites exhibited better wear resistance compared to pure Ni, which could be explained by the formation of a lubricious tribo-layer during sliding and the good bonding between the Ni matrix and the reinforcing phases.

Keywords: composites, microscopy, sintering, wear

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