Search results for: structural substance

Authors: Iman Shabanzadeh

Abstract:

In terms of its geopolitical position, Iran has been one of the main centers of migration movements in the world in recent decades. However, the policy makers' lack of preparation in completing the cycle of social integration of these immigrants, especially the second and third generation, has caused these people to always be prone to leave the country and immigrate to developed and industrialized countries. In this research, the issue of integration of immigrants in Iran from the perspective of four indicators, "Identity Documents", "Access to Banking Services", "Access to Health and Treatment Services" and "Obtaining a Driver's License" will be analyzed. The research method is descriptive-analytical. To collect information, library and document sources in the field of laws and regulations related to immigrants' rights in Iran, semi-structured interviews with experts have been used. The investigations of this study show that none of the residence documents of immigrants in Iran guarantee the full enjoyment of basic citizenship rights for them. In fact, the function of many of these identity documents, such as the census card, educational support card, etc., is only to prevent crossing the border, and none of them guarantee the basic rights of citizenship. Therefore, for many immigrants, the difference between legality and illegality is only in the risk of crossing the border, and this has led to the spread of the habit of illegal presence for them. Despite this, it seems that there is no clear and coherent policy framework around the issue of foreign immigrants in the country. This policy incoherence can be clearly seen in the diversity and plurality of identity and legal documents of the citizens present in the country and the policy maker's lack of planning to integrate and organize the identity of this huge group. Examining the differences and socioeconomic inequalities between immigrants and the native Iranian population shows that immigrants have been poorly integrated into the structures of Iranian society from an economic and social point of view.

Keywords: immigrants, social integration, citizen services, structural inequality

Procedia PDF Downloads 44

Authors: Vikash Yadav, Ashish Arora

Abstract:

Microorganisms have self-defense mechanisms to protect themselves from toxic environments. Phenolic acid decarboxylase(pad) is responsible for the defense against toxicity caused by phenolic acids, converting them into less toxic vinyl derivatives. The transcription of the pad gene is regulated by a negative transcription factor, phenolic acid decarboxylase regulators (PadR), in a substrate-inducible manner. The PadR family members share the conserved DNA-binding features and interact with the operator DNA using a winged helix-turn-helix (wHTH) motif, which contains a three-helix motif and a β-stranded wing. The members of this family function as transcriptional regulators that are involved in various cellular survival processes, such as toxin production, detoxification, multidrug resistance, antibiotic biosynthesis, and carbon catabolism. Rv1176 of Mycobacterium tuberculosis H37Rv has been assigned to the PadR family protein that remains to be structurally and functionally uncharacterized. To reveal the structural mechanism by which Rv1176 could regulates effector-responsive transcription, several experiments were performed, including Electrophoretic Mobility Shift Assay (EMSA) for DNA protein interaction, differential scanning calorimetry (DSC) and Differential Scanning Fluorimetry (DSF) for temperature and ligand-dependent protein stability, Circular Dichroism (CD) spectroscopy for secondary structure analysis. Further, to evaluate the functional role of Rv1176, the intracellular survival of recombinant M. smegmatis was examined in murine macrophage cell line J774A.1 and different stressed conditions like oxidative, pH, and nutritive stress. All these studies demonstrated that Rv1176 could behave as a transcription regulator and its expression in recombinant M. smegmatis increases intracellular survival.

Keywords: EMSA, Mycobacterium tuberculosis, PadR family protein, transcriptional regulator

Procedia PDF Downloads 78

Authors: Sylwia Orzechowska, Andrzej Wróbel, Eugeniusz Rokita

Abstract:

The mineralization is a curious problem of connective tissues. Factors which may play a decisive role in the regulation of the yellow ligaments (YL) mineralization are still open questions. The aim of the studies was a detailed description of the chemical composition and morphology of mineral deposits in the human yellow ligaments. Investigations of the structural features of deposits were used to explain the impact of various factors on mineralization process. The studies were carried out on 24 YL samples, surgically removed from patients suffer from spinal canal stenosis and the patients who sustained a trauma. The micro-computed tomography was used to describe the morphology of mineral deposits. The X-ray fluorescence method and Fourier transform infrared spectroscopy were applied to determine the chemical composition of the samples. In order to eliminate the effect of blur in microtomographic images, the correction method of partial volume effect was used. The mineral deposits appear in 60% of YL samples, both in patients with a stenosis and following injury. The mineral deposits have a heterogeneous structure and they are a mixture of the tissue and mineral grains. The volume of mineral grains amounts to (1.9 ± 3.4)*10-3 mm3 while the density distribution of grains occurs in two distinct ranges (1.75 - 2.15 and 2.15-2.5) g/cm3. Application of the partial volume effect correction allows accurate calculations by eliminating the averaging effect of gray levels in tomographic images. The B-type carbonate-containing hydroxyapatite constitutes the mineral phase of majority YLs. The main phase of two samples was calcium pyrophosphate dihydrate (CPPD). The elemental composition of minerals in all samples is almost identical. This pathology may be independent on the spine diseases and it does not evoke canal stenosis. The two ranges of grains density indicate two stages of grains growth and the degree of maturity. The presence of CPPD crystals may coexist with other pathologies.

Keywords: FTIR, micro-tomography, mineralization, spinal ligaments

Procedia PDF Downloads 377

Authors: Qi Peng

Abstract:

The Chinese sport sector is currently undergoing a dramatic institutional change. A sport system that was heavily dominated by the government is starting to shift towards one that is driven by the market. During the past sixty years, the Chinese Football Association (CFA), although ostensibly a ‘non-governmental organization’, has been in fact operated under the close supervision and control of the government. The double-identity of CFA has taken most of the blame for the poor performance of the Chinese football team, especially the men’s team. In 2015, a policy initiated by the Chinese government introduced a potentially radical change to the institutional structure of CFA by delegating the power of government agency – the General Administration of Sport of China - to the organization (CFA) itself. Against such background, an overarching research question was brought up- will an organization remained institutionalized within the system change in response to the external (policy) jolt? To answer this question, three principal data collection methods were employed: document review, participant observation and semi-structured interviews. Document review provides the mapping of the structural and cultural framework in which the CFA functions during the change process. The author have had the chance to interact closely with the organization as participant observer in the organization for a period of time, long enough to collect the data, but never too long to get biased view of the situation. This stage enables the author to gain an in-depth understanding of how CFA managed to restructure the governance and legitimacy. Conducting semi-structured interviews with staff within the CFA and from staff within selected stakeholders of CFA also provided a crucial step to gain an insight into the factors for change as well as the implications of the change. A wide range of interviewees that have been and to be interviewed include: CFA members (senior officials and staff); local football associations members; senior Chinese Super League football club managers; CFA Super League Co., LTD (senior officials and staff); CSL broadcasters; Chinese Olympic Committee members. The preliminary research data shows that the CFA is currently undergoing two levels of change: although the settings of CFA has been gradually restructured (organizational framework), the organizational values and beliefs remain almost the same as the CFA before the reform. This means that the plan of shifting from a governmental agency to an autonomous association is an going process, and that organizational core beliefs and values are more difficult to change than its structural framework. This is due to the inertia of the organizational history and the effect of institutionalization. The change of Chinese Football Association is looked at as a pioneering sport organization in China to undertake the “decoupling” road. It is believed that many other sport organizations, especially sport governing bodies will follow the step of CFA in the near future. Therefore, the experience of CFA change is worthy of studying.

Keywords: Chinese Football Association, Organizational Change, Organizational Culture, Structural Framework

Procedia PDF Downloads 344

Authors: Sahin Yakut, H. Kemal Ulutas, Deniz Deger

Abstract:

Plasma Assisted Physical Vapor Deposition (PAPVD) method used to produce Poly(ethylene oxide) (pPEO) thin films. Depositions were progressed at various plasma discharge powers as 0, 2, 5 and 30 W for pPEO at 500nm film thicknesses. The capacitance and dielectric dissipation of the thin films were measured at 0,1-107 Hz frequency range and 173-353 K temperature range by an impedance analyzer. Then, alternative conductivity (σac) and activation energies were derived from capacitance and dielectric dissipation. σac of conventional PEO (PEO precursor) was measured to determine the effect of plasma discharge. Differences were observed between the alternative conductivity of PEO’s and pPEO’s depending on plasma discharge power. By this purpose, structural characterization techniques such as Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FT-IR) were applied on pPEO thin films. Structural analysis showed that density of crosslinking is plasma power dependent. The crosslinking density increases with increasing plasma discharge power and this increase is displayed as increasing dynamic glass transition temperatures at DSC results. Also, shifting of frequencies of some type of bond vibrations, belonging to bond vibrations produced after fragmentation because of plasma discharge, were observed at FTIR results. The dynamic glass transition temperatures obtained from alternative conductivity results for pPEO consistent with the results of DSC. Activation energies exhibit Arrhenius behavior. Activation energies decrease with increasing plasma discharge power. This behavior supports the suggestion expressing that long polymer chains and long oligomers are fragmented into smaller oligomers or radicals.

Keywords: activation energy, dielectric spectroscopy, organic thin films, plasma polymer

Procedia PDF Downloads 300

Authors: Danny Barash

Abstract:

Riboswitches are RNA genetic control elements that were originally discovered in bacteria and provide a unique mechanism of gene regulation. They work without the participation of proteins and are believed to represent ancient regulatory systems in the evolutionary timescale. One of the biggest challenges in riboswitch research is that many are found in prokaryotes but only a small percentage of known riboswitches have been found in certain eukaryotic organisms. The few examples of eukaryotic riboswitches were identified using sequence-based bioinformatics search methods that include some slight structural considerations. These pattern-matching methods were the first ones to be applied for the purpose of riboswitch detection and they can also be programmed very efficiently using a data structure called affix arrays, making them suitable for genome-wide searches of riboswitch patterns. However, they are limited by their ability to detect harder to find riboswitches that deviate from the known patterns. Several methods have been developed since then to tackle this problem. The most commonly used by practitioners is Infernal that relies on Hidden Markov Models (HMMs) and Covariance Models (CMs). Profile Hidden Markov Models were also carried out in the pHMM Riboswitch Scanner web application, independently from Infernal. Other computational approaches that have been developed include RMDetect by the use of 3D structural modules and RNAbor that utilizes Boltzmann probability of structural neighbors. We have tried to incorporate more sophisticated secondary structure considerations based on RNA folding prediction using several strategies. The first idea was to utilize window-based methods in conjunction with folding predictions by energy minimization. The moving window approach is heavily geared towards secondary structure consideration relative to sequence that is treated as a constraint. However, the method cannot be used genome-wide due to its high cost because each folding prediction by energy minimization in the moving window is computationally expensive, enabling to scan only at the vicinity of genes of interest. The second idea was to remedy the inefficiency of the previous approach by constructing a pipeline that consists of inverse RNA folding considering RNA secondary structure, followed by a BLAST search that is sequence-based and highly efficient. This approach, which relies on inverse RNA folding in general and our own in-house fragment-based inverse RNA folding program called RNAfbinv in particular, shows capability to find attractive candidates that are missed by Infernal and other standard methods being used for riboswitch detection. We demonstrate attractive candidates found by both the moving-window approach and the inverse RNA folding approach performed together with BLAST. We conclude that structure-based methods like the two strategies outlined above hold considerable promise in detecting riboswitches and other conserved RNAs of functional importance in a variety of organisms.

Keywords: riboswitches, RNA folding prediction, RNA structure, structure-based methods

Procedia PDF Downloads 234

Authors: Yuet Wah Echo Yeung

Abstract:

Practice learning is an important component of social work education. Practice educators are charged with the responsibility to support and enable learning while students are on placement. They also play a key role in teaching students to integrate theory and practice, as well as assessing their performance. Current literature highlights the structural factors that make it difficult for practice educators to create a positive learning environment for students. Practice educators find it difficult to give sufficient attention to their students because of the lack of workload relief, the increasing emphasis on managerialism and bureaucratisation, and a range of competing organisational and professional demands. This paper reports the challenges practice educators face and how they manage these challenges in this context. Semi-structured face-to-face interviews were conducted with thirteen practice educators who support students in statutory and voluntary social care settings in the Northwest of England. Interviews were conducted between April and July 2017 and each interview lasted about 40 minutes. All interviews were recorded and transcribed. All practice educators are experienced social work practitioners with practice experience ranging from 6 to 42 years. On average they have acted as practice educators for 13 years and all together have supported 386 students. Our findings reveal that apart from the structural factors that impact how practice educators perform their roles, they also faced other challenges when supporting students on placement. They include difficulty in engaging resistant students, complexity in managing power dynamics in the context of practice learning, and managing the dilemmas of fostering a positive relationship with students whilst giving critical feedback. Suggestions to enhance the practice educators’ role include support from organisations and social work teams; effective communication with university tutors, and a forum for practice educators to share good practice and discuss placement issues.

Keywords: social work education, placement challenges, practice educator, practice learning

Procedia PDF Downloads 191

Authors: David Ugalde, Arturo Castillo, Leopoldo Breschi

Abstract:

The Tuned Mass Dampers (TMDs) are an effective system for mitigating vibrations in building structures. These dampers have traditionally focused on the protection of high-rise buildings against earthquakes and wind loads. The Camara Chilena de la Construction (CChC) building, built in 2018 in Santiago, Chile, is a 21-story RC wall building equipped with a 150-ton TMD and instrumented with six permanent accelerometers, offering an opportunity to monitor the dynamic response of this damped structure. This paper presents the system identification of the CChC building using power spectral density plots of ambient vibration and two seismic events (5.5 Mw and 6.7 Mw). Linear models of the building with and without the TMD are used to compute the theoretical natural periods through modal analysis and simulate the response of the building through response history analysis. Results show that natural periods obtained from both ambient vibrations and earthquake records are quite similar to the theoretical periods given by the modal analysis of the building model. Some of the experimental periods are noticeable by simple inspection of the earthquake records. The accelerometers in the first story better captured the modes related to the building podium while the upper accelerometers clearly captured the modes related to the tower. The earthquake simulation showed smaller accelerations in the model with TMD that are similar to that measured by the accelerometers. It is concluded that the system identification through power spectral density shows consistency with the expected dynamic properties. The structural health monitoring of the CChC building confirms the advantages of seismic protection technologies such as TMDs in seismic prone areas.

Keywords: system identification, tuned mass damper, wall buildings, seismic protection

Procedia PDF Downloads 125

Authors: Pouriya Darabiyan, Hadis Nazari, Kourosh Zarea, Saeed Ghanbari, Zeinab Raiesifar, Morteza Khafaie, Hanna Tuvesson

Abstract:

Introduction Since the beginning of mobile phone addiction, alexithymia, depression, anxiety and stress have been stated as risk factors for Internet addiction, so this study was conducted with the aim of investigating the relationship between Alexithymia and Mobile phone addiction along with the mediating role of anxiety, stress and depression. Materials and methods In this descriptive-analytical and cross-sectional study in 2022, 412 students School of Nursing & Midwifery of Ahvaz Jundishapur University of Medical Sciences were included in the study using available sampling method. Data collection tools were: Demographic Information Questionnaire, Toronto Alexithymia Scale (TAS-20), Depression, Anxiety, Stress Scale (DASS-21) and Mobile Phone Addiction Index (MPAI). Frequency, Pearson correlation coefficient test and linear regression were used to describe and analyze the data. Also, structural equation models and path analysis method were used to investigate the direct and indirect effects as well as the total effect of each dimension of Alexithymia on Mobile phone addiction with the mediating role of stress, depression and anxiety. Statistical analysis was done by SPSS version 22 and Amos version 16 software. Results Alexithymia was a predictive factor for mobile phone addiction. Also, Alexithymia had a positive and significant effect on depression, anxiety and stress. Depression, anxiety and stress had a positive and significant effect on mobile phone addiction. Depression, anxiety and stress variables played the role of a relative mediating variable between Alexithymia and mobile phone addiction. Alexithymia through depression, anxiety and stress also has an indirect effect on Internet addiction. Conclusion Alexithymia is a predictive factor for mobile phone addiction; And the variables of depression, anxiety and stress play the role of a relative mediating variable between Alexithymia and mobile phone addiction.

Keywords: alexithymia, mobile phone, depression, anxiety, stress

Procedia PDF Downloads 99

Authors: Navid Kaboudi, Ali Shayanfar

Abstract:

Introduction: Feeding infants with safe milk from the beginning of their life is an important issue. Drugs which are used by mothers can affect the composition of milk in a way that is not only unsuitable, but also toxic for infants. Consuming permeable drugs during that sensitive period by mother could lead to serious side effects to the infant. Due to the ethical restrictions of drug testing on humans, especially women, during their lactation period, computational approaches based on structural parameters could be useful. The aim of this study is to develop mechanistic models to predict the M/P ratio of drugs during breastfeeding period based on their structural descriptors. Methods: Two hundred and nine different chemicals with their M/P ratio were used in this study. All drugs were categorized into two groups based on their M/P value as Malone classification: 1: Drugs with M/P>1, which are considered as high risk 2: Drugs with M/P>1, which are considered as low risk Thirty eight chemical descriptors were calculated by ACD/labs 6.00 and Data warrior software in order to assess the penetration during breastfeeding period. Later on, four specific models based on the number of hydrogen bond acceptors, polar surface area, total surface area, and number of acidic oxygen were established for the prediction. The mentioned descriptors can predict the penetration with an acceptable accuracy. For the remaining compounds (N= 147, 158, 160, and 174 for models 1 to 4, respectively) of each model binary regression with SPSS 21 was done in order to give us a model to predict the penetration ratio of compounds. Only structural descriptors with p-value<0.1 remained in the final model. Results and discussion: Four different models based on the number of hydrogen bond acceptors, polar surface area, and total surface area were obtained in order to predict the penetration of drugs into human milk during breastfeeding period About 3-4% of milk consists of lipids, and the amount of lipid after parturition increases. Lipid soluble drugs diffuse alongside with fats from plasma to mammary glands. lipophilicity plays a vital role in predicting the penetration class of drugs during lactation period. It was shown in the logistic regression models that compounds with number of hydrogen bond acceptors, PSA and TSA above 5, 90 and 25 respectively, are less permeable to milk because they are less soluble in the amount of fats in milk. The pH of milk is acidic and due to that, basic compounds tend to be concentrated in milk than plasma while acidic compounds may consist lower concentrations in milk than plasma. Conclusion: In this study, we developed four regression-based models to predict the penetration class of drugs during the lactation period. The obtained models can lead to a higher speed in drug development process, saving energy, and costs. Milk/plasma ratio assessment of drugs requires multiple steps of animal testing, which has its own ethical issues. QSAR modeling could help scientist to reduce the amount of animal testing, and our models are also eligible to do that.

Keywords: logistic regression, breastfeeding, descriptors, penetration

Procedia PDF Downloads 71

Authors: Khaled Barkaoui

Abstract:

Research on second-language (L2) learning tends to focus on comparing students with different levels of proficiency at one point in time. However, to understand L2 development, we need more longitudinal research. In this study, we adopt a longitudinal approach to examine changes in three indicators of L2 ability, complexity, accuracy, and fluency (CAF), as reflected in the writing of L2 learners when writing on different tasks before and after a period L2 instruction. Each of 85 Chinese learners of English at three levels of English language proficiency responded to two writing tasks (independent and integrated) before and after nine months of English-language study in China. Each essay (N= 276) was analyzed in terms of numerous CAF indices using both computer coding and human rating: number of words written, number of errors per 100 words, ratings of error severity, global syntactic complexity (MLS), complexity by coordination (T/S), complexity by subordination (C/T), clausal complexity (MLC), phrasal complexity (NP density), syntactic variety, lexical density, lexical variation, lexical sophistication, and lexical bundles. Results were then compared statistically across tasks, L2 proficiency levels, and time. Overall, task type had significant effects on fluency and some syntactic complexity indices (complexity by coordination, structural variety, clausal complexity, phrase complexity) and lexical density, sophistication, and bundles, but not accuracy. L2 proficiency had significant effects on fluency, accuracy, and lexical variation, but not syntactic complexity. Finally, fluency, frequency of errors, but not accuracy ratings, syntactic complexity indices (clausal complexity, global complexity, complexity by subordination, phrase complexity, structural variety) and lexical complexity (lexical density, variation, and sophistication) exhibited significant changes after instruction, particularly for the independent task. We discuss the findings and their implications for assessment, instruction, and research on CAF in the context of L2 writing.

Keywords: second language writing, Fluency, accuracy, complexity, longitudinal

Procedia PDF Downloads 153

Authors: T. D. Ibragimov, A. R. Imamaliyev, G. M. Bayramov

Abstract:

The polymer network liquid crystals based on the liquid crystals Н37 and 5CB with polymethylvinilpirydine (PMVP) and polyethylene glycol (PEG) have been developed. Mesogene substance 4-n-heptyoxibenzoic acid (HOBA) is served for stabilization of obtaining composites. Kinetics of network formation is investigated by methods of polarization microscopy and integrated small-angle scattering. It is shown that gel-like states of the composite H-37 + PMVP + HOBA and 5CB+PEG+HOBA are formed at polymer concentration above 7 % and 9 %, correspondingly. At slow cooling, the system separates into a liquid crystal –rich phase and a liquid crystal-poor phase. At this case, transition of these phases in the H-37 + PMVP + HOBA (87 % + 12 % + 1 %) composite to an anisotropic state occurs at 49 оС and и 41 оС, accordingly, while the composite 5CB+PEG+HOBA (85% +13 % +2%) passes to anisotropic state at 36 оС corresponding to the isotropic-nematic transition of pure 5CB. The basic electro-optic parameters of the obtained composites are determined at room temperature. It is shown that the threshold voltage of the composite H-37 + PMVP + HOBA increase in comparison with pure H-37 and, accordingly, there is a shift of voltage dependence of rise times to the high voltage region. The contrast ratio worsens while decay time improves in comparison with the pure liquid crystal at all applied voltage. The switching times of the composite 5CB + PEG + HOBA (85% +13 % +2%) show anomalous behavior connected with incompleteness of the transition to an anisotropic state. Experimental results are explained by phase separation of the system, diminution of a working area of electro-optical effects and influence of areas with the high polymer concentration on areas with their low concentration.

Keywords: liquid crystals, polymers, small-angle scattering, optical properties

Procedia PDF Downloads 617

Authors: Madhav Khadilkar

Abstract:

Construction of a large standby reservoir was required to provide secure water supply. The new reservoir was required to be constructed at the same location of an abandoned old open pond due to space constraints. Some investigations were carried out earlier to improvise and re-commission the existing pond. But due to a lack of quantified risk of settlement from voids in the underlying limestone, the shallow foundations were not found feasible. Since the reservoir was resting on hard strata for about three-quarter of plan area and one quarter was resting on soil underlying with limestone and considerably low subgrade modulus. Further investigations were carried out to ascertain the locations and extent of voids within the limestone. It was concluded that the risk due to lime dissolution was acceptably low, and the site was found geotechnically feasible. The hazard posed by limestone dissolution was addressed through the integrated structural and geotechnical analysis and design approach. Finite Element Analysis was carried out to quantify the stresses and differential settlement due to various probable loads and soil-structure interaction. Walls behaving as cantilever under operational loads were found undergoing in-plane bending and tensile forces due to soil-structure interaction. Sensitivity analysis for varying soil subgrade modulus was carried out to check the variation in the response of the structure and magnitude of stresses developed. The base slab was additionally checked for the loss of soil contact due to lime pocket formations at random locations. The expansion and contraction joints were planned to receive minimal additional forces due to differential settlement. The reservoir was designed to sustain the actions corresponding to allowable deformation limits per code, and geotechnical measures were proposed to achieve the soil parameters set in structural analysis.

Keywords: differential settlement, limestone dissolution, reservoir, soil structure interaction

Procedia PDF Downloads 155

Authors: Sumaia Jawad, Shalaweh Salem, Walid Kamal, Nicolette Roman

Abstract:

Background: HIV patients have many social problems like depression, which adversely affects their quality of life. HIV infection is linked to psychological distress such as anxiety. In terms of coping styles, avoidant emotion-focused strategies such as fatalism, wishful thinking and self-blame are associated with higher levels of psychological distress in persons with HIV. In Cairo, Egypt current services are not adapted to provide advice and psychological support to people living with HIV to help them develop problem-solving skills to cope with the stress of living with HIV. Yet, no studies have examined the relationship between quality of life, psychological distress and coping strategies of persons living with HIV/AIDS in Egypt. Therefore, the purpose of this study was to examine the relationship between quality of life, psychological distress and coping strategies of persons living with HIV/AIDS in Cairo, Egypt. Methods: This study used a quantitative methodology with a cross-sectional correlational design. The data was collected using: Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q), Depression, Anxiety and Stress Scale (DASS) and Cope Inventory. The sample consisted of 202 participants who accessed the National AIDS Program (NAP). The data was analysed using the Statistical Program for Social Science V23 (SPSS). Results: The results show that psychological distress and certain coping styles such as substance abuse and behavioural disengagement negatively predict the quality of life of patients with HIV/AIDS. Positive predictors included coping styles such as active coping, self-distraction, venting, positive reframing, humor, acceptance, and religion. Conclusions: It would probably be best to reduce psychological distress and increase coping styles in order to improve the quality of life of patients with HIV/AIDS.

Keywords: HIV/AIDS, quality of life, psychological distress, coping strategies

Procedia PDF Downloads 409

Authors: Gichun Cha, Changgil Lee, Seunghee Park

Abstract:

The objective of the study is to construct the shape management method contributing to the safety of the large structure. In Korea, the research of the shape management is lack because of the new attempted technology. Terrestrial Laser Scanning (TLS) is used for measurements of large structures. TLS provides an efficient way to actively acquire accurate the point clouds of object surfaces or environments. The point clouds provide a basis for rapid modeling in the industrial automation, architecture, construction or maintenance of the civil infrastructures. TLS produce a huge amount of point clouds. Registration, Extraction and Visualization of data require the processing of a massive amount of scan data. The octree can be applied to the shape management of the large structure because the scan data is reduced in the size but, the data attributes are maintained. The octree space partitioning generates the voxel of 3D space, and the voxel is recursively subdivided into eight sub-voxels. The point cloud of scan data was converted to voxel and sampled. The experimental site is located at Sungkyunkwan University. The scanned structure is the steel-frame bridge. The used TLS is Leica ScanStation C10/C5. The scan data was condensed 92%, and the octree model was constructed with 2 millimeter in resolution. This study presents octree space partitioning for handling the point clouds. The basis is created by shape management of the large structures such as double-deck tunnel, building and bridge. The research will be expected to improve the efficiency of structural health monitoring and maintenance. "This work is financially supported by 'U-City Master and Doctor Course Grant Program' and the National Research Foundation of Korea(NRF) grant funded by the Korea government (MSIP) (NRF- 2015R1D1A1A01059291)."

Keywords: 3D scan data, octree space partitioning, shape management, structural health monitoring, terrestrial laser scanning

Procedia PDF Downloads 297

Authors: Bruce Wrightsman

Abstract:

Construction and design are inexorably linked. Traditional building methodologies, including those using wood, comprise a series of material layers differentiated and separated from each other. This results in the separation of two agencies of building envelope (skin) separate from the structure. However, from a material performance position reliant on additional materials, this is not an efficient strategy for the building. The merits of traditional platform framing are well known. However, its enormous effectiveness within wood-framed construction has seldom led to serious questioning and challenges in defining what it means to build. There are several downsides of using this method, which is less widely discussed. The first and perhaps biggest downside is waste. Second, its reliance on wood assemblies forming walls, floors and roofs conventionally nailed together through simple plate surfaces is structurally inefficient. It requires additional material through plates, blocking, nailers, etc., for stability that only adds to the material waste. In contrast, when we look back at the history of wood construction in airplane and boat manufacturing industries, we will see a significant transformation in the relationship of structure with skin. The history of boat construction transformed from indigenous wood practices of birch bark canoes to copper sheathing over wood to improve performance in the late 18th century and the evolution of merged assemblies that drives the industry today. In 1911, Swiss engineer Emile Ruchonnet designed the first wood monocoque structure for an airplane called the Cigare. The wing and tail assemblies consisted of thin, lightweight, and often fabric skin stretched tightly over a wood frame. This stressed skin has evolved into semi-monocoque construction, in which the skin merges with structural fins that take additional forces. It provides even greater strength with less material. The monocoque, which translates to ‘mono or single shell,’ is a structural system that supports loads and transfers them through an external enclosure system. They have largely existed outside the domain of architecture. However, this uniting of divergent systems has been demonstrated to be lighter, utilizing less material than traditional wood building practices. This paper will examine the role monocoque systems have played in the history of wood construction through lineage of boat and airplane building industries and its design potential for wood building systems in architecture through a case-study examination of a unique wood construction approach. The innovative approach uses a wood monocoque system comprised of interlocking small wood members to create thin shell assemblies for the walls, roof and floor, increasing structural efficiency and wasting less than 2% of the wood. The goal of the analysis is to expand the work of practice and the academy in order to foster deeper, more honest discourse regarding the limitations and impact of traditional wood framing.

Keywords: wood building systems, material histories, monocoque systems, construction waste

Procedia PDF Downloads 78

Authors: Basavaraj R. Endigeri, S. G. Sarganachari

Abstract:

Steel is widely used in machine parts, structural equipment and many other applications. In many steel structural elements, holes of different shapes and orientations are made with a view to satisfy the design requirements. The presence of holes in steel elements creates stress concentration, which eventually reduce the mechanical strength of the structure. Therefore, it is of great importance to investigate the state of stress around the holes for the safety and properties design of such elements. By literature survey, it is known that till date, there is no analytical solution to reduce the stress concentration by providing auxiliary holes at a definite location and radii in a steel plate. The numerical method can be used to determine the optimum location and radii of auxiliary holes. In the present work plate with an elliptical hole, for a steel material subjected to uniaxial load is analyzed and the effect of stress concentration is graphically represented .The introduction of auxiliary holes at a optimum location and radii with its effect on stress concentration is also represented graphically. The finite element analysis package ANSYS 11.0 is used to analyse the steel plate. The analysis is carried out using a plane 42 element. Further the ANSYS optimization model is used to determine the location and radii for optimum values of auxiliary hole to reduce stress concentration. All the results for different diameter to plate width ratio are presented graphically. The results of this study are in the form of the graphs for determining the locations and diameter of optimal auxiliary holes. The graph of stress concentration v/s central hole diameter to plate width ratio. The Finite Elements results of the study indicates that the stress concentration effect of central elliptical hole in an uniaxial loaded plate can be reduced by introducing auxiliary holes on either side of the central circular hole.

Keywords: finite element method, optimization, stress concentration factor, auxiliary holes

Procedia PDF Downloads 453

Authors: Xiaoyong He

Abstract:

The manipulation of THz waves is still a challenging task due to lack of natural materials interacted with it strongly. Designed by tailoring the characters of unit cells (meta-molecules), the advance of metamaterials (MMs) may solve this problem. However, because of Ohmic and radiation losses, the performance of MMs devices is subjected to the dissipation and low quality factor (Q-factor). This dilemma may be circumvented by Fano resonance, which arises from the destructive interference between a bright continuum mode and dark discrete mode (or a narrow resonance). Different from symmetric Lorentz spectral curve, Fano resonance indicates a distinct asymmetric line-shape, ultrahigh quality factor, steep variations in spectrum curves. Fano resonance is usually realized through symmetry breaking. However, if concentric double rings (DR) are placed closely to each other, the near-field coupling between them gives rise to two hybridized modes (bright and narrowband dark modes) because of the local asymmetry, resulting into the characteristic Fano line shape. Furthermore, from the practical viewpoint, it is highly desirable requirement that to achieve the modulation of Fano spectral curves conveniently, which is an important and interesting research topics. For current Fano systems, the tunable spectral curves can be realized by adjusting the geometrical structural parameters or magnetic fields biased the ferrite-based structure. But due to limited dispersion properties of active materials, it is still a tough work to tailor Fano resonance conveniently with the fixed structural parameters. With the favorable properties of extreme confinement and high tunability, graphene is a strong candidate to achieve this goal. The DR-structure possesses the excitation of so-called “trapped modes,” with the merits of simple structure and high quality of resonances in thin structures. By depositing graphene circular DR on the SiO2/Si/ polymer substrate, the tunable Fano resonance has been theoretically investigated in the terahertz regime, including the effects of graphene Fermi level, structural parameters and operation frequency. The results manifest that the obvious Fano peak can be efficiently modulated because of the strong coupling between incident waves and graphene ribbons. As Fermi level increases, the peak amplitude of Fano curve increases, and the resonant peak position shifts to high frequency. The amplitude modulation depth of Fano curves is about 30% if Fermi level changes in the scope of 0.1-1.0 eV. The optimum gap distance between DR is about 8-12 μm, where the value of figure of merit shows a peak. As the graphene ribbon width increases, the Fano spectral curves become broad, and the resonant peak denotes blue shift. The results are very helpful to develop novel graphene plasmonic devices, e.g. sensors and modulators.

Keywords: graphene, metamaterials, terahertz, tunable

Procedia PDF Downloads 344

Authors: H. Aripin, I. Made Joni, Edvin Priatna, Nundang Busaeri, Svilen Sabchevski

Abstract:

In this investigation, manganese has been produced from medium grade manganese ore from Karangnunggal mine (West Java, Indonesia). The ores were grinded using a jar mill to pass through a 150 mesh sieve. The effects of keeping it at a temperature of 1200 °C in methane gas on the structural properties have been studied. The material’s properties have been characterized on the basis of the experimental data obtained using X-ray fluorescence (XRF), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. It has been found that the ore contains MnO₂ as the main constituents at about 46.80 wt.%. It can be also observed that the ore particles are agglomerated forming dense grains with different texture and morphology. The irregular-shaped grains with dark contrast, the large brighter grains, and smaller grains with bright texture and smooth surfaces are associated with the presence of manganese, calcium, and quartz, respectively. From XRD patterns, MnO₂ is reduced to hausmannite (Mn₃O₄), manganosite (MnO) and manganese carbide (Mn₇C₃). At a temperature of 1200°C the keeping time does not have any effect on the formation of crystals and the crystalline phases remain almost unchanged in the time range from 15 to 90 minutes. An increase of the keeping time up to 45 minutes during the sintering process leads to an increase of the MnO concentration, while at 90 minutes, the concentration decreases. At longer keeping times the excess reaction of the methane gas and manganese oxide in the ore causes an increase of carbon deposition. As a result, it blocks the particle surface and then hinders the reduction process of manganese oxide. From FTIR spectrum allows one to explain that the appearance of C=O stretching mode arises from absorption of atmospheric methane and manganese oxide of the ore. The intensity of this band increases with increasing the keeping time, indicating an increase of carbon deposition on the surface of manganese oxide.

Keywords: manganese, medium grade manganese ore, structural properties, keeping the temperature, carbon deposition

Procedia PDF Downloads 155

Authors: Ákos Wolf, Richard P. Ray

Abstract:

Due to the introduction of Eurocode 8, the structural design for seismic and dynamic effects has become more significant in Hungary. This has emphasized the need for more effort to describe the behavior of structures under these conditions. Soil conditions have a significant effect on the response of structures by modifying the stiffness and damping of the soil-structural system and by modifying the seismic action as it reaches the ground surface. Shear modulus (G) and shear wave velocity (v_s), which are often measured in the field, are the fundamental dynamic soil properties for foundation vibration problems, liquefaction potential and earthquake site response analysis. There are several laboratory and in-situ measurement techniques to evaluate dynamic soil properties, but unfortunately, they are often too expensive for general design practice. However, a significant number of correlations have been proposed to determine shear wave velocity or shear modulus from Cone Penetration Tests (CPT), which are used more and more in geotechnical design practice in Hungary. This allows the designer to analyze and compare CPT and seismic test result in order to select the best correlation equations for Hungarian soils and to improve the recommendations for the Hungarian geologic conditions. Based on a literature review, as well as research experience in Hungary, the influence of various parameters on the accuracy of results will be shown. This study can serve as a basis for selecting and modifying correlation equations for Hungarian soils. Test data are taken from seven locations in Hungary with similar geologic conditions. The shear wave velocity values were measured by seismic CPT. Several factors are analyzed including soil type, behavior index, measurement depth, geologic age etc. for their effect on the accuracy of predictions. The final results show an improved prediction method for Hungarian soils

Keywords: CPT correlation, dynamic soil properties, seismic CPT, shear wave velocity

Procedia PDF Downloads 246

Authors: Muhammad Aji Fajari, Ririt Aprilin Sumarsono

Abstract:

Particular instability of structural building under lateral load (e.g earthquake) will rise due to irregularity in vertical and horizontal direction as stated in SNI 03-1762-2012. The conventional slab has been considered for its less contribution in increasing the stability of the structure, except special slab system such as flat slab turned into account. In this paper, the analysis of flat slab system at Sequis Tower located in South Jakarta will be assessed its performance under earthquake. It consists of 6 floors of the basement where the flat slab system is applied. The flat slab system will be the main focus in this paper to be compared for its performance with conventional slab system under earthquake. Regarding the floor plan of Sequis Tower basement, re-entrant corner signed for this building is 43.21% which exceeded the allowable re-entrant corner is 15% as stated in ASCE 7-05 Based on that, the horizontal irregularity will be another concern for analysis, otherwise vertical irregularity does not exist for this building. Flat slab system is a system where the slabs use drop panel with shear head as their support instead of using beams. Major advantages of flat slab application are decreasing dead load of structure, removing beams so that the clear height can be maximized, and providing lateral resistance due to lateral load. Whilst, deflection at middle strip and punching shear are problems to be detail considered. Torsion usually appears when the structural member under flexure such as beam or column dimension is improper in ratio. Considering flat slab as alternative slab system will keep the collapse due to torsion down. Common seismic load resisting system applied in the building is a shear wall. Installation of shear wall will keep the structural system stronger and stiffer affecting in reduced displacement under earthquake. Eccentricity of shear wall location of this building resolved the instability due to horizontal irregularity so that the earthquake load can be absorbed. Performing linear dynamic analysis such as response spectrum and time history analysis due to earthquake load is suitable as the irregularity arise so that the performance of structure can be significantly observed. Utilization of response spectrum data for South Jakarta which PGA 0.389g is basic for the earthquake load idealization to be involved in several load combinations stated on SNI 03-1726-2012. The analysis will result in some basic seismic parameters such as period, displacement, and base shear of the system; besides the internal forces of the critical member will be presented. Predicted period of a structure under earthquake load is 0.45 second, but as different slab system applied in the analysis then the period will show a different value. Flat slab system will probably result in better performance for the displacement parameter compare to conventional slab system due to higher contribution of stiffness to the whole system of the building. In line with displacement, the deflection of the slab will result smaller for flat slab than a conventional slab. Henceforth, shear wall will be effective to strengthen the conventional slab system than flat slab system.

Keywords: conventional slab, flat slab, horizontal irregularity, response spectrum, shear wall

Procedia PDF Downloads 191

Authors: Sanja O. Podunavac-Kuzmanović, Strahinja Z. Kovačević, Lidija R. Jevrić

Abstract:

Prion is a protein substance whose certain form is considered as infectious agent. It is presumed to be the cause of the transmissible spongiform encephalopathies (TSEs). The protein it is composed of, called PrP, can fold in structurally distinct ways. At least one of those 3D structures is transmissible to other prion proteins. Prions can be found in brain tissue of healthy people and have certain biological role. The structure of prions naturally occurring in healthy organisms is marked as PrPc, and the structure of infectious prion is labeled as PrPSc. PrPc may play a role in synaptic plasticity and neuronal development. Also, it may be required for neuronal myelin sheath maintenance, including a role in iron uptake and iron homeostasis. PrPSc can be considered as an environmental pollutant. The main aim of this study was to carry out the molecular modeling and calculation of molecular descriptors (lipophilicity, physico-chemical and topological descriptors) of structurally diverse compounds which can be considered as anti-prion agents. Molecular modeling was conducted applying ChemBio3D Ultra version 12.0 software. The obtained 3D models were subjected to energy minimization using molecular mechanics force field method (MM2). The cutoff for structure optimization was set at a gradient of 0.1 kcal/Åmol. The Austin Model 1 (AM-1) was used for full geometry optimization of all structures. The obtained set of molecular descriptors is applied in analysis of similarities and dissimilarities among the tested compounds. This study is an important step in further development of quantitative structure-activity relationship (QSAR) models, which can be used for prediction of anti-prion activity of newly synthesized compounds.

Keywords: chemometrics, molecular modeling, molecular descriptors, prions, QSAR

Procedia PDF Downloads 322

Authors: B. S. Abdelwahed, B. B. Belkassem

Abstract:

Beam-column joints are a critical part in reinforced concrete RC frames designed for inelastic response to several external loads. Investigating the behaviour of the exterior RC beam-column joints has attracted many researchers in the past decades due to its critical influence on the overall behaviour of RC moment-resisting frames subjected to lateral loads. One of the most critical zones in moment-resistant frames is the knee joints because of restraints associated with providing limited anchorage length to the beam and column longitudinal reinforcement in it and consequentially causes a lot of damage in such building frames. Previous numerical simulations focussed mainly on the exterior and interior joints, for knee joint further work is still needed to investigate its behaviour and discuss its affecting parameters. Structural response for an RC knee beam-column joint is performed in this study using LS-DYNA. Three-dimensional finite element (FE) models of an RC knee beam-column joint are described and verified with experimental results available in literature; this is followed by a parametric study to investigate the influence of the concrete compressive strength, the presence of lateral beams and increasing beam reinforcement ratio. It is shown that the concrete compressive strength has a significant effect on shear capacity, load-deflection characteristics and failure modes of an RC knee beam-column joints but to a certain limit, the presence of lateral beams increased the joint confinement and reduced the rate of concrete degradation in the joint after reaching ultimate joint capacity, added to that an increase in the maximum load resistance. Increasing beam reinforcement ratio is found to improve the flexural resistance of the anchored beam bars and increase the joint maximum load resistance.

Keywords: beam reinforcement ratio, joint confinement, numerical simulation, reinforced concrete beam-column joints, structural performance

Procedia PDF Downloads 463

Authors: T. S. Soliman, A. G. Galyas, E. V. Rusinova, S. A. Vshivkov

Abstract:

The liquid crystals combining properties of a liquid and an anisotropic crystal substance play an important role in a science and engineering. Molecules of cellulose and its derivatives have rigid helical conformation, stabilized by intramolecular hydrogen bonds. Therefore the macromolecules of these polymers are capable to be ordered at dissolution and form liquid crystals of cholesteric type. Phase diagrams of solutions of some cellulose derivatives are known. However, little is known about the effect of a magnetic field on the viscosity of polymer solutions. The systems hydroxypropyl cellulose (HPC) – ethanol, HPC – ethylene glycol, HPC–DМАA, HPC–DMF, ethyl cellulose (EC)–ethanol, EC–DMF, were studied in the presence and absence of magnetic field. The solution viscosity was determined on a Rheotest RN 4.1 rheometer. The effect of a magnetic field on the solution properties was studied with the use of two magnets, which induces a magnetic-field-lines directed perpendicularly and parallel to the rotational axis of a rotor. Application of the magnetic field is shown to be accompanied by an increase in the additional assembly of macromolecules, as is evident from a gain in the radii of light scattering particles. In the presence of a magnetic field, the long chains of macromolecules are oriented in parallel with field lines. Such an orientation is associated with the molecular diamagnetic anisotropy of macromolecules. As a result, supramolecular particles are formed, especially in the vicinity of the region of liquid crystalline phase transition. The magnetic field leads to the increase in viscosity of solutions. The results were used to plot the concentration dependence of η/η0, where η and η0 are the viscosities of solutions in the presence and absence of a magnetic field, respectively. In this case, the values of viscosity corresponding to low shear rates were chosen because the concentration dependence of viscosity at low shear rates is typical for anisotropic systems. In the investigated composition range, the values of η/η0 are described by a curve with a maximum.

Keywords: rheology, liquid crystals, magnetic field, cellulose ethers

Procedia PDF Downloads 348

Authors: Ashley R. Logsdon, Becky F. Antle, Cynthia M. Kamer

Abstract:

This study examines the cost and benefits of a family treatment drug court in an urban county in a southeastern state. Additionally, this cost analysis will provide a detailed description of the type and cost of activities to produce the services provided to child welfare families. This study utilized return-on-investment analysis, which uses child welfare practices, disaggregates them into separate activities and estimates costs for these activities including child-level placement data for total cost of care for the child. Direct and indirect costs were considered as well as saving calculations what costs would be associated with child welfare outcomes both short and long term. The costs included were general program costs (salaries, drug screens, transportation, childcare, parent education, program evaluation, visitation, incentives) or personnel costs for other team members (judges, court administrators, child welfare workers, child welfare supervisors, and community mental health provider). The savings that were used in the study were length of time in out of home care, Medicaid costs, substance exposed births, emergency room utilization and jail/probation costs. This study documents an overall savings of between $168,993.30 and $837,993.30. The total savings per family divided by the 40 families who have participated in the program was between $4,224.83 to $20,949.83 per family. The results of this cost benefit analysis are consistent with prior research documenting savings associated with out of home care and jail/probation; however, there are also unique contributions of this study to the literature on cost effectiveness of family treatment drug courts. We will present recommendations for further utilization of family treatment drug courts and how to expand the current model.

Keywords: child welfare, cost analysis, family drug court, family treatment drug court

Procedia PDF Downloads 184

Authors: Jeet Chakraborty, Sanjay Dutta

Abstract:

Antibiotic resistance by bacteria has proved to be a severe threat to mankind in recent times, and this fortifies an urgency to design and develop potent antibacterial small molecules/compounds with nonconventional mechanisms than the conventional ones. DNA carries the genetic signature of any organism, and bacteria maintain their genomic DNA inside the cell in a well-regulated compact form with the help of various nucleoid associated proteins like HU, HNS, etc. These proteins control various fundamental processes like gene expression, replication, etc., inside the cell. Alteration of the native DNA structure of bacteria can lead to severe consequences in cellular processes inside the bacterial cell that ultimately result in the death of the organism. The change in the global DNA structure by small molecules initiates a plethora of cellular responses that have not been very well investigated. Echinomycin and Triostin-A are biologically active Quinoxaline small molecules that typically consist of a quinoxaline chromophore attached with an octadepsipeptide ring. They bind to double-stranded DNA in a sequence-specific way and have high activity against a wide variety of bacteria, mainly against Gram-positive ones. To date, few synthetic quinoxaline scaffolds were synthesized, displaying antibacterial potential against a broad scale of pathogenic bacteria. QNOs (Quinoxaline N-oxides) are known to target DNA and instigate reactive oxygen species (ROS) production in bacteria, thereby exhibiting antibacterial properties. The divergent role of Quinoxaline small molecules in medicinal research qualifies them for the evaluation of their antimicrobial properties as a potential candidate. The previous study from our lab has given new insights on a 6-nitroquinoxaline derivative 1d as an intercalator of DNA, which induces conformational changes in DNA upon binding.7 The binding event observed was dependent on the presence of a crucial benzyl substituent on the quinoxaline moiety. This was associated with a large induced CD (ICD) appearing in a sigmoidal pattern upon the interaction of 1d with dsDNA. The induction of DNA superstructures by 1d at high Drug:DNA ratios was observed that ultimately led to DNA condensation. Eviction of invitro-assembled nucleosome upon treatment with a high dose of 1d was also observed. In this work, monoquinoxaline derivatives of 1d were synthesized by various modifications of the 1d scaffold. The set of synthesized 6-nitroquinoxaline derivatives along with 1d were all subjected to antibacterial evaluation across five different bacteria species. Among the compound set, 3a displayed potent antibacterial activity against Staphylococcus aureus bacteria. 3a was further subjected to various biophysical studies to check whether the DNA structural alteration potential was still intact. The biological response of S. aureus cells upon treatment with 3a was studied using various cell biology processes, which led to the conclusion that 3d can initiate DNA damage in the S. aureus cells. Finally, the potential of 3a in disrupting preformed S.aureus and S.epidermidis biofilms was also studied.

Keywords: DNA structural change, antibacterial, intercalator, DNA superstructures, biofilms

Procedia PDF Downloads 169

Authors: Kotchamon Yodkhum, Thawatchai Phaechamud

Abstract:

Hydrophobic chitosan-based materials have been developed as controlled drug delivery system. This study was aimed to prepare and evaluate chitosan-aluminum monostearate composite dispersion (CLA) as fabricating liquid for construct a hydrophobic, controlled-release solid drug delivery matrix. This work was attempted to blend hydrophobic substance, aluminum monostearate (AMS), with chitosan in acidic aqueous medium without using any surfactants or grafting reaction, and high temperature during mixing that are normally performed when preparing hydrophobic chitosan system. Lactic acid solution (2%w/v) was employed as chitosan solvent. CLA dispersion was prepared by dispersing different amounts of AMS (1-20% w/w) in chitosan solution (4% w/w) with continuous agitation using magnetic stirrer for 24 h. Effect of AMS amount on physicochemical properties of the dispersion such as viscosity, rheology and particle size was evaluated. Morphology of chitosan-AMS complex (dispersant) was observed under inverted microscope and atomic force microscope. Stability of CLA dispersions was evaluated after preparation within 48 h. CLA dispersions containing AMS less than 5 % w/w exhibited rheological behavior as Newtonian while that containing higher AMS amount exhibited as pseudoplastic. Particle size of the dispersant was significantly smaller when AMS amount was increased up to 5% w/w and was not different between the higher AMS amount system. Morphology of the dispersant under inverted microscope displayed irregular shape and their size exhibited the same trend with particle size measurement. Observation of the dispersion stability revealed that phase separation occurred faster in the system containing higher AMS amount which indicated lower stability of the system. However, the dispersions were homogeneous and stable more than 12 hours after preparation that enough for fabrication process. The prepared dispersions had ability to be fabricated as a porous matrix via lyophilization technique.

Keywords: chitosan, aluminum monostearate, dispersion, controlled-release

Procedia PDF Downloads 392

Authors: Niharul Alam

Abstract:

The development of energy efficient, economic and eco-friendly synthetic protocols for metal nanoparticles (NPs) with tailor-made structural properties and biocompatibility is a highly cherished goal for researchers working in the field of nanoscience and nanotechnology. In this context, green chemistry is highly relevant and the 12 principles of Green Chemistry can be explored to develop such synthetic protocols which are practically implementable. One of the most promising green chemical synthetic methods which can serve the purpose is biogenic synthetic protocol, which utilizes non-toxic multifunctional reactants derived from natural, biological sources ranging from unicellular organisms to higher plants that are often characterized as “medicinal plants”. Over the past few years, a plethora of medicinal plants have been explored as the source of this kind of multifunctional green chemical agents. In this presentation, we focus on the syntheses of stable monometallic Au and Ag NPs and also bimetallic Au/Ag alloy NPs with highly efficient catalytic property using aqueous extract of leaves of Indian Curry leaf plat (Murraya koenigii Spreng.; Fam. Rutaceae) as green multifunctional agents which is extensively used in Indian traditional medicine and cuisine. We have also studied the interaction between the synthesized metal NPs and surface-adsorbed fluorescent moieties, quercetin and quercetin glycoside which are its chemical constituents. This helped us to understand the surface property of the metal NPs synthesized by this plant based biogenic route and to predict a plausible mechanistic pathway which may help in fine-tuning green chemical methods for the controlled synthesis of various metal NPs in future. We observed that simple experimental parameters e.g. pH and temperature of the reaction medium, concentration of multifunctional agent and precursor metal ions play important role in the biogenic synthesis of Au NPs with finely tuned structures.

Keywords: green multifunctional agent, metal nanoparticles, biogenic synthesis

Procedia PDF Downloads 431

Authors: Laura C. Loaiza, Elodie Salager, Nicolas Louvain, Athmane Boulaoued, Antonella Iadecola, Patrik Johansson, Lorenzo Stievano, Vincent Seznec, Laure Monconduit

Abstract:

Lithium-ion batteries (LIBs) have an important place among energy storage devices due to their high capacity and good cyclability. However, the advancements in portable and transportation applications have extended the research towards new horizons, and today the development is hampered, e.g., by the capacity of the electrodes employed. Silicon and germanium are among the considered modern anode materials as they can undergo alloying reactions with lithium while delivering high capacities. It has been demonstrated that silicon in its highest lithiated state can deliver up to ten times more capacity than graphite (372 mAh/g): 4200 mAh/g for Li₂₂Si₅ and 3579 mAh/g for Li₁₅Si₄, respectively. On the other hand, germanium presents a capacity of 1384 mAh/g for Li₁₅Ge₄, and a better electronic conductivity and Li ion diffusivity as compared to Si. Nonetheless, the commercialization potential of Ge is limited by its cost. The synergetic effect of Si₁₋ₓGeₓ alloys has been proven, the capacity is increased compared to Ge-rich electrodes and the capacity retention is increased compared to Si-rich electrodes, but the exact performance of this type of electrodes will depend on factors like specific capacity, C-rates, cost, etc. There are several reports on various formulations of Si₁₋ₓGeₓ alloys with promising LIB anode performance with most work performed on complex nanostructures resulting from synthesis efforts implying high cost. In the present work, we studied the electrochemical mechanism of the Si₀.₅Ge₀.₅ alloy as a realistic micron-sized electrode formulation using carboxymethyl cellulose (CMC) as the binder. A combination of a large set of in situ and operando techniques were employed to investigate the structural evolution of Si₀.₅Ge₀.₅ during lithiation and delithiation processes: powder X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), Raman spectroscopy, and 7Li solid state nuclear magnetic resonance spectroscopy (NMR). The results have presented a whole view of the structural modifications induced by the lithiation/delithiation processes. The Si₀.₅Ge₀.₅ amorphization was observed at the beginning of discharge. Further lithiation induces the formation of a-Liₓ(Si/Ge) intermediates and the crystallization of Li₁₅(Si₀.₅Ge₀.₅)₄ at the end of the discharge. At really low voltages a reversible process of overlithiation and formation of Li₁₅₊δ(Si₀.₅Ge₀.₅)₄ was identified and related with a structural evolution of Li₁₅(Si₀.₅Ge₀.₅)₄. Upon charge, the c-Li₁₅(Si₀.₅Ge₀.₅)₄ was transformed into a-Liₓ(Si/Ge) intermediates. At the end of the process an amorphous phase assigned to a-SiₓGey was recovered. Thereby, it was demonstrated that Si and Ge are collectively active along the cycling process, upon discharge with the formation of a ternary Li₁₅(Si₀.₅Ge₀.₅)₄ phase (with a step of overlithiation) and upon charge with the rebuilding of the a-Si-Ge phase. This process is undoubtedly behind the enhanced performance of Si₀.₅Ge₀.₅ compared to a physical mixture of Si and Ge.

Keywords: lithium ion battery, silicon germanium anode, in situ characterization, X-Ray diffraction

Procedia PDF Downloads 285

Authors: Carlos Riascos, Peter Thomson

Abstract:

Real-time hybrid simulation (RTHS) is a modern cyber-physical technique used for the experimental evaluation of complex systems, that treats the system components with predictable behavior as a numerical substructure and the components that are difficult to model as an experimental substructure. Therefore it is an attractive method for evaluation of the response of civil structures under earthquake, wind and anthropic loads. Another practical application of RTHS is the evaluation of control systems, as these devices are often nonlinear and their characterization is an important step in the design of controllers with the desired performance. In this paper, the response of three-story shear frame controlled by a tuned liquid column damper (TLCD) and subject to base excitation is considered. Both passive and semi-active control strategies were implemented and are compared. While the passive TLCD achieved a reduction of 50% in the acceleration response of the main structure in comparison with the structure without control, the semi-active TLCD achieved a reduction of 70%, and was robust to variations in the dynamic properties of the main structure. In addition, a RTHS was implemented with the main structure modeled as a linear, time-invariant (LTI) system through a state space representation and the TLCD, with both control strategies, was evaluated on a shake table that reproduced the displacement of the virtual structure. Current assessment measures for RTHS were used to quantify the performance with parameters such as generalized amplitude, equivalent time delay between the target and measured displacement of the shake table, and energy error using the measured force, and prove that the RTHS described in this paper is an accurate method for the experimental evaluation of structural control systems.

Keywords: structural control, hybrid simulation, tuned liquid column damper, semi-active sontrol strategy

Procedia PDF Downloads 297