Search results for: rate dependent material properties

Authors: Ji Hoi Heo, Jun Seong Park, Hyo Kim

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Geopolymer is an inorganic material synthesized by alkali activation of source materials rich in soluble SiO₂ and Al₂O₃. Many researches have studied the effect of aluminum species on the synthesis of geopolymer. However, it is still unclear about the influence of Al additives on the properties of geopolymer. The current study identified the role of the Al additive on the thermal performance of fly ash based geopolymer and observing the microstructure development of the composite. NaOH pellets were dissolved in water for 14 M (14 moles/L) sodium hydroxide solution which was used as an alkali activator. The weight ratio of alkali activator to fly ash was 0.40. Sodium aluminate powder was employed as an Al additive and added in amounts of 0.5 wt.% to 2 wt.% by the weight of fly ash. The mixture of alkali activator and fly ash was cured in a 75°C dry oven for 24 hours. Then, the hardened geopolymer samples were exposed to 300°C, 600°C and 900°C for 2 hours, respectively. The initial compressive strength after oven curing increased with increasing sodium aluminate content. It was also observed in SEM results that more amounts of geopolymer composite were synthesized as sodium aluminate was added. The compressive strength increased with increasing heating temperature from 300°C to 600°C regardless of sodium aluminate addition. It was consistent with the ATR-FTIR results that the peak position related to asymmetric stretching vibrations of Si-O-T (T: Si or Al) shifted to higher wavenumber as the heating temperature increased, indicating the further geopolymer reaction. In addition, geopolymer sample with higher content of sodium aluminate showed better compressive strength. It was also reflected on the IR results by more shift of the peak position assigned to Si-O-T toward the higher wavenumber. However, the compressive strength decreased after being exposed to 900°C in all samples. The degree of reduction in compressive strength was decreased with increasing sodium aluminate content. The deterioration in compressive strength was most severe in the geopolymer sample without sodium aluminate additive, while the samples with sodium aluminate addition showed better thermal durability at 900°C. This is related to the phase transformation with the occurrence of nepheline phase at 900°C, which was most predominant in the sample without sodium aluminate. In this work, it was concluded that sodium aluminate could be a good additive in the geopolymer synthesis by showing the improved compressive strength at elevated temperatures.

Keywords: compressive strength, fly ash based geopolymer, microstructure development, Na-aluminate

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Authors: John Masani Nduko, Joseph Wafula Matofari

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Many spontaneously fermented milk products are produced in Kenya, where they are integral to the human diet and play a central role in enhancing food security and income generation via small-scale enterprises. Fermentation enhances product properties such as taste, aroma, shelf-life, safety, texture, and nutritional value. Some of these products have demonstrated therapeutic and probiotic effects although recent reports have linked some to death, biotoxin infections, and esophageal cancer. These products are mostly processed from poor quality raw materials under unhygienic conditions resulting to inconsistent product quality and limited shelf-lives. Though very popular, research on their processing technologies is low, and none of the products has been produced under controlled conditions using starter cultures. To modernize the processing technologies for these products, our study aims at describing the microbiology and biochemistry of a representative Kenyan spontaneously fermented milk product, Mursik using modern biotechnology (DNA sequencing) and their chemical composition. Moreover, co-creation processes reflecting stakeholders’ experiences on traditional fermented milk production technologies and utilization, ideals and senses of value, which will allow the generation of products based on common ground for rapid progress will be discussed. Knowledge of the value of clean starting raw material will be emphasized, the need for the definition of fermentation parameters highlighted, and standard equipment employment to attain controlled fermentation discussed. This presentation will review the available information regarding traditional fermented milk (Mursik) and highlight our current research work on the application of molecular approaches (metagenomics) for the valorization of Mursik production process through starter culture/ probiotic strains isolation and identification, and quality and safety aspects of the product. The importance of the research and future research areas on the same subject will also be highlighted.

Keywords: lactic acid bacteria, high throughput biotechnology, spontaneous fermentation, Mursik

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Authors: José Neves, M. Rosário Martins, Fátima Candeias, Diana Ferreira, Sílvia Arantes, Júlio Cruz-Morais, Guida Gomes, Joaquim Macedo, António Abelha, Henrique Vicente

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Some plants of genus Schinus have been used in the folk medicine as topical antiseptic, digestive, purgative, diuretic, analgesic or antidepressant, and also for respiratory and urinary infections. Chemical composition of essential oils of S. molle and S. terebinthifolius had been evaluated and presented high variability according with the part of the plant studied and with the geographic and climatic regions. The pharmacological properties, namely antimicrobial, anti-tumoural and anti-inflammatory activities are conditioned by chemical composition of essential oils. Taking into account the difficulty to infer the pharmacological properties of Schinus essential oils without hard experimental approach, this work will focus on the development of a decision support system, in terms of its knowledge representation and reasoning procedures, under a formal framework based on Logic Programming, complemented with an approach to computing centered on Artificial Neural Networks and the respective Degree-of-Confidence that one has on such an occurrence.

Keywords: artificial neuronal networks, essential oils, knowledge representation and reasoning, logic programming, Schinus molle L., Schinus terebinthifolius Raddi

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Authors: A. P. I. Popoola, O. S. I. Fayomi, V. S. Aigbodion

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Mild steel has found many engineering applications due to its great formability, availability, low cost and good mechanical properties among others. However its functionality and durability is subject of concern due to corrosion deterioration. Based on these Yttrium is selected as reinforcing particles using electroplating process in this work to enhance the corrosion resistance. Bath formulation of zinc-yttrium was prepared at moderated temperature and pH, to coat mild steel sample. Corrosion and wear behaviour were analyzed using electrochemical potentiostat and abrasive test rig. The composition and microstructure of coated films were investigated standard method. The microstructure of the deposited plate obtained from optimum (10%Yttrium) bath revealed fine-grained deposit of the alloy in the presence of condensation product and hence modified the morphology of zinc–yttrium alloy deposit. It is demonstrated that by adding yttria particles, mild steel can be strengthened with improved polarization behaviour and higher resistance to corrosive in sodium chloride solutions. Microhardness of the coating compared to plain mild steel have increased before and after heat treatment, and an increased wear resistance was also obtained from the modified coating of zinc-yttrium.

Keywords: microhardness, zinc-yttrium, coating, mild steel, microstructure, wear, corrosion

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Authors: Sharadha G., Suresh Kanakkanavar

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Background: Placenta previa is a condition characterized by partial or complete implantation of the placenta in the lower uterine segment. It is one of the main causes of vaginal bleeding in the third trimester and a significant cause of maternal and perinatal morbidity and mortality. Materials and Methods: This is an observational study involving 130 patients diagnosed with placenta previa and satisfying inclusion criteria. The demographic data, clinical, surgical, and treatment, along with maternal and neonatal outcome parameters, were noted in proforma. Results: The incidence of placenta previa among scarred uterus was 1.32%, and in unscarred uterus was 0.67%. The mean age of the study population was 27.12±4.426years. High parity, high abortion rate, multigravida status, and less gestational age at delivery were commonly seen in scarred uterus compared to unscarred uterus. Complete placenta previa, anterior placental position, and adherent placenta were significantly associated with a scarred uterus compared to an unscarred uterus. The rate of caesarean hysterectomy was higher in the scarred uterus, along with statistical association to previous lower-segment caesarean sections. Intraoperative procedures like uterine artery ligation, bakri balloon insertion, and iliac artery ligation were higher in the scarred group. The maternal intensive care unit admission rate was higher in the scarred group and also showed its statistical association with previous lower segment caesarean section. Neonatal outcomes in terms of pre-term birth, still birth, neonatal intensive care unit admission, and neonatal death, though higher in the scarred group, did not differ statistically among the groups. Conclusion: Advancing maternal age, multiparity, prior uterine surgeries, and abortions are independent risk factors for placenta previa. Maternal morbidity is higher in the scarred uterus group compared to the unscarred group. Neonatal outcomes did not differ statistically among the groups. This knowledge would help the obstetricians to take measures to reduce the incidence of placenta previa and scarred uterus which would improve the fetomaternal outcome of placenta previa.

Keywords: placenta previa, scarred uterus, unscarred uterus, adherent placenta

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Authors: A. Jatau, Q. Majeed, H. M. Bandiya

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The efficacy of five local spices, namely; Hot pepper (Capsicum annum L.), Black pepper (Piper guinese Schum and Thonn), Sweet basil (Occimum canum Sim), African nut-meg (Monodora myristica Dunal), and Ginger (Zingiber officianale Ross) with conventional insecticide against the D. maculatus was studied under ambient laboratory conditions. The plants were pulverized into powders and applied at the rate of 1.0, 2.0 and 3.0g per 25g of disinfected dried fish. The same amount of fish (25g) was treated with 5ml of 1.0, 2.0 and 3.0 percent solution of conventional insecticide (dichlorvos) and air dried for 2hrs. Ten newly hatched 1st instar larvae (24hrs old) were introduced into each powdered smoked fish in separate beakers. Untreated control was also set up. Observation on the mortality and development were recorded daily until the larvae pupated. Each of the treated smoked fish showed significant (p<0.05) effect on the larval mortality and development when compared with the control. The Piper guinense was as efficacious as dichlorvos in killing all the larvae (100%) at all concentrations before pupation. Ocimum Canunm gave the second best results (50.00, 63.33 and 100%), while the other three spices resulted in less than 50% mortalities at all rate of application. The spice powders were also observed to have extended the larval developmental period. Thus, the spices tested can be recommended for the control of D. maculatus.

Keywords: development, dermestes maculatus, insecticide, local spices, mortality

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Authors: Haidy S. Ghali, Engy Serag, A. Samer Ezeldin

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Copper is an essential raw material used in the construction industry. During the year 2021 and the first half of 2022, the global market suffered from a significant fluctuation in copper raw material prices due to the aftermath of both the COVID-19 pandemic and the Russia-Ukraine war, which exposed its consumers to an unexpected financial risk. Thereto, this paper aims to develop two ANN-LSTM price prediction models, using Python, that can forecast the average monthly copper prices traded in the London Metal Exchange; the first model is a multivariate model that forecasts the copper price of the next 1-month and the second is a univariate model that predicts the copper prices of the upcoming three months. Historical data of average monthly London Metal Exchange copper prices are collected from January 2009 till July 2022, and potential external factors are identified and employed in the multivariate model. These factors lie under three main categories: energy prices and economic indicators of the three major exporting countries of copper, depending on the data availability. Before developing the LSTM models, the collected external parameters are analyzed with respect to the copper prices using correlation and multicollinearity tests in R software; then, the parameters are further screened to select the parameters that influence the copper prices. Then, the two LSTM models are developed, and the dataset is divided into training, validation, and testing sets. The results show that the performance of the 3-Month prediction model is better than the 1-Month prediction model, but still, both models can act as predicting tools for diverse economic situations.

Keywords: copper prices, prediction model, neural network, time series forecasting

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Authors: Mitsuhiro Okayasu, Lele Yang, Koji Shimotsu

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The effects of microstructural characteristics on the mechanical and hydrogen embrittlement properties of 1,800MPa grade hot stamping carbon steel were investigated experimentally. The tensile strength increased with increasing the hot stamping temperature until around 921°C, but that decreased with increasing the temperature in more than 921°C due to the increment of the size of lath martensite and prior austenite. With the hot stamping process, internal strain was slightly created in the sample, which led to the slight increment of the hardness value although no clear change of the microstructural formation was detected. Severity of hydrogen embrittlement was investigated using the hot stamped carbon steels after the immersion in a hydrogen gas, and that was directly attributed to the infiltration of the hydrogen into their grain boundaries. The high strength carbon steel with tiny lath martensite microstructure could make severe hydrogen brittleness as the hydrogen was strongly penetrated in the grain boundaries in the hydrogen gas for a month. Because of weak embrittlement for the as-received carbon (ferrite and pearlite), hydrogen embrittlement is caused by the high internal strain and high dislocation density. The hydrogen embrittlement for carbon steel is attributed to amount of the hydrogen immersed in-between grain boundaries, which is caused by the dislocation density and internal strain.

Keywords: hydrogen embrittlement, hot stamping process, carbon steel, mechanical property

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Authors: Ahmad Amiri, Hamed Khajeh Arzani, Md. Salim Newaz Kazi, Bee Teng Chew

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Obviously, the behavior of thermophysical properties of covalently functionalized MWNT-based water nanofluids cannot be predicted from the predicted models. We present a study of the specific heat capacity, effective thermal conductivity, density and viscosity of coolants containing functionalized multi-wall carbon nanotubes (MWNT-COOH) with carboxyl groups at different temperatures. After synthesizing of MWNT-COOH-based water, measurements on the prepared coolants were made at various concentrations by different experimental methods. While thermal conductivity of nanofluids illustrated a significant increase, the specific heat capacity of the samples showed a downward behavior with increasing temperature. The viscosity was investigated in different shear rates and temperatures. Interestingly, the specific heat capacity of all prepared nanofluids was decreased with increasing concentration. Also, the density of the MWNT-COOH-based water nanofluids increased and decreased smoothly with increasing MWNT-COOH concentration and temperature, respectively.

Keywords: carbon nanotubes, coolant, heat capacity, density, viscosity, thermal conductivity

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Authors: Moaine Jebara, Lionel Boillereaux, Sofiane Belhabib, Michel Havet, Alain Sarda, Pierre Mousseau, Rémi Deterre

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Energy consumption efficiency is a major concern for the material processing industry such as thermoforming process and molding. Indeed, these systems should deliver the right amount of energy at the right time to the processed material. Recent technical development, as well as the particularities of the heating system dynamics, made the Model Predictive Control (MPC) one of the best candidates for thermal control of several production processes like molding and composite thermoforming to name a few. The main principle of this technique is to use a dynamic model of the process inside the controller in real time in order to anticipate the future behavior of the process which allows the current timeslot to be optimized while taking future timeslots into account. This study presents a procedure based on a predictive control that brings balance between optimality, simplicity, and flexibility of its implementation. The development of this approach is progressive starting from the case of a single zone before its extension to the multizone and/or multisource case, taking thus into account the thermal couplings between the adjacent zones. After a quadratic formulation of the MPC criterion to ensure the thermal control, the linear expression is retained in order to reduce calculation time thanks to the use of the ARMAX linear decomposition methods. The effectiveness of this approach is illustrated by experiment and simulation.

Keywords: energy efficiency, linear decomposition methods, model predictive control, mold heating systems

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Authors: Ghodhbani Salah, Jemili Farah

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With the growth of cyber attacks, information safety has become an important issue all over the world. Many firms rely on security technologies such as intrusion detection systems (IDSs) to manage information technology security risks. IDSs are considered to be the last line of defense to secure a network and play a very important role in detecting large number of attacks. However the main problem with today’s most popular commercial IDSs is generating high volume of alerts and huge number of false positives. This drawback has become the main motivation for many research papers in IDS area. Hence, in this paper we present a data mining technique to assist network administrators to analyze and reduce false positive alarms that are produced by an IDS and increase detection accuracy. Our data mining technique is unsupervised clustering method based on hybrid ANT algorithm. This algorithm discovers clusters of intruders’ behavior without prior knowledge of a possible number of classes, then we apply K-means algorithm to improve the convergence of the ANT clustering. Experimental results on real dataset show that our proposed approach is efficient with high detection rate and low false alarm rate.

Keywords: intrusion detection system, alarm filtering, ANT class, ant clustering, intruders’ behaviors, false alarms

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Authors: Mahmoud Tarek, Alaa Obeida, Mai Magdy, Khalid Hussein, Aly Shalaby

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Background: More doctors are complaining of burnout than before, Burnout is a state of physical and mental exhaustion caused by the doctor’s lifestyle, unfortunately, Medical errors are also more likely in those suffering from burnout and these may result in malpractice suits. Methodology: It is a retrospective audit of burnout response on all neonatologists over a 9 months period. We gathered data using burnout questionnaire, it was obtained from 23 physicians, the physicians divided into 5 categories according to the final score of the 28 questions in the questionnaire. Category 1 with score from 28-38 with almost no work stress, category 2 with score (38-50) who express a low amount of job related stress, category 3 with score (51-70) with moderate amount of stress, category 4 with score (71-90) those express a high amount of job stress and begun to burnout, category 5 with score (91 and above) who are under a dangerous amount of stress and advanced stage of burnout. Results: 33 neonatologists have received the questionnaire, 23 responses were sent back with a response rate of 69.6%. The results showed that 61% of physicians fall in category 4, 31% of the physician in category 5, while 8% of physicians equally distributed between category 2 and 3 (4% each of them). On the other hand, there is no physician present in category 1. Conclusion: Burnout is prevalent in SNICUs, So interventions to minimize burnout prevalence may be of greater importance as this may be reflected indirectly on medical conditions of the patients and physicians, efforts should be done to decrease this high rate of burnout.

Keywords: Cairo, work overload, exhaustion, surgery, neonatal ICU

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Authors: A. Mohamed, A. El-Aziz

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The pH of the body plays a great role in the degradation kinetics of biodegradable Mg-Ca orthopedic implants. At the location of fracture, the pH of the body becomes no longer neutral which draws the attention towards studying a range of different pH values of the body fluid. In this study, the pH of Hank’s balanced salt solution (HBSS) was modified by phosphate buffers into an aggressive acidic pH 1.8, a slightly acidic pH 5.3 and an alkaline pH 8.1. The biodegradation of Mg-0.8Ca implant was tested in those three different media using immersion test and electrochemical polarization means. It was proposed that the degradation rate has increased with decreasing the pH of HBSS. The immersion test revealed weight gain for all the samples followed by weight loss as the immersion time increased. The highest weight gain was pronounced for the acidic pH 1.8 and the least weight gain was observed for the alkaline pH 8.1. This was in agreement with the electrochemical polarization test results where the degradation rate was found to be high (7.29 ± 2.2 mm/year) in the aggressive acidic solution of pH 1.8 and relatively minimum (0.31 ± 0.06 mm/year) in the alkaline medium of pH 8.1. Furthermore, it was confirmed that the pH of HBSS has reached a steady state of an alkaline pH (~pH 11) at the end of the two-month immersion period regardless of the initial pH of the solution. Finally, the corrosion products formed on the samples’ surface were investigated by SEM, EDX and XRD analyses that revealed the formation of magnesium and calcium phosphates with different morphologies according to the pH.

Keywords: biodegradable, electrochemical polarization means, orthopedics, immersion test, simulated body fluid

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Authors: Nina Tsvetkova, Rumen Harizanov, Aleksandra Ivanova, Iskra Rainova, Nina Yancheva-Petrova, Dimitar Strashimirov, Raina Enikova, Mihaela Videnova, Eleonora Kaneva, Iskren Kaftandjiev, Viktoria Levterova, Ivan Simeonovski, Nikolay Yanev, Georgi Hinkov

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The Pneumocystis jirovecii (P. jirovecii) and protozoan of the genera Acanthamoeba, Cryptosporidium, and Toxoplasma gondii are opportunistic pathogens that can cause life-threatening infections in immunocompromised patients. Aim of the study was to evaluate the coinfection rate with opportunistic protozoal agents among Bulgarian patients diagnosed with P. jirovecii pneumonia. Thirty-eight pulmonary samples were collected from 38 patients (28 HIV-infected) with P. jirovecii infection. P. jirovecii DNA was detected by real-time PCR targeting the large mitochondrial subunit ribosomal RNA gene. Acanthamoeba was determined by genus-specific conventional PCR assay. Real-time PCR for the detection of a Toxoplasma gondii and Cryptosporidium DNA fragment was used. Pneumocystis DNA was detected in all 38 specimens; 28 (73.7%) were from HIV-infected patients. Three (10,7%) of them were co-infected with T. gondii and 1 (3.6%) with Cryptosporidium. In the group of non-HIV-infected (n=10), Cryptosporidium DNA was detected in an infant (10%). Acanthamoeba DNA was not found in the tested samples. The current study showed a relatively low rate of coinfections of Cryptosporidium spp./T. gondii and P. jirovecii in the Bulgarian patients studied.

Keywords: coinfection, opportunistic protozoal agents, Pneumocystis jirovecii, pulmonary infections

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Authors: Joachim Onyike

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The Federal Government of Nigeria in 2012 came up with a new National Housing Policy; one of its major objectives was to make housing affordable to the poor. Six years down the line, this study was carried out to find out whether the poor have fared better under the new housing policy. Owerri, the capital of Imo State, was adopted as a case study to mirror the situation nationwide. The study population was made up of low-income civil servants, i.e., grade levels 1–6 in the Imo State Civil Service. The study looked at household size, household income, rental levels, house prices, costs of major building materials, land values, land tenure, the interest rate on mortgages, inflation rate, and the status of government interventions, owing to their obvious effect on housing affordability by the low-income earners. The study made use of physical observations, questionnaires, and interviews as well as library studies to elicit relevant information. Housing affordability by the subject population did not improve. It rather dropped. The study came to the conclusion that in spite of the new National Housing Policy, housing affordability by the low-income earners has not improved. The policy as it affects the poor has not been duly implemented by both Federal and State Governments.

Keywords: house prices, housing affordability, housing policy, land values, low-income earners

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Authors: Oluwatayo Abioye, Anthony Okoh

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In the past view decades; human has experienced outbreaks of infections caused by pathogenic Vibrio spp which are commonly found in aquatic milieu. Asides the well-known Vibrio cholerae, discovery of other pathogens in this genus has been on the increase. While the dynamics of occurrence and distribution of Vibrio spp have been linked to some physicochemical parameters in salt water, data in relation to fresh water is limited. Hence, two rivers of importance in the Eastern Cape, South Africa were selected for this study. In all, eleven sampling sites were systematically identified and relevant physicochemical parameters, as well as Vibrio spp density, were determined for the period of six months using standard instruments and methods. Results were statistically analysed to determined key physicochemical parameters that determine the density of Vibrio spp in the selected rivers. Results: The density of Vibrio spp in all the sampling points ranges between < 1 CFU/mL to 174 x 10-2 CFU/mL. The physicochemical parameters of some of the sampling points were above the recommended standards. The regression analysis showed that Vibrio density in the selected rivers depends on a complex relationship between various physicochemical parameters. Conclusion: This study suggests that Vibrio spp density in fresh water does not depend on only temperature and salinity as suggested by earlier studies on salt water but rather on a complex relationship between several physicochemical parameters.

Keywords: vibrio density, physicochemical properties, pathogen, aquatic milieu

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Authors: Iman Zafarparandeh, Muzammil Mumtaz, Paniz Taherzadeh, Deniz Erbulut

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The instability in the atlantoaxial joint may occur due to cervical surgery, congenital anomalies, and trauma. There are different types of fixation techniques proposed for restoring the stability and preventing harmful neurological deterioration. Application of the screw constructs has become a popular alternative to the older techniques for stabilizing the joint. The main difference between the various screw constructs is the type of the screw which can be lateral mass screw, pedicle screw, transarticular screw, and translaminar screw. The aim of this paper is to study the effect of three popular screw constructs fixation techniques on the biomechanics of the atlantoaxial joint using the finite element (FE) method. A three-dimensional FE model of the upper cervical spine including the skull, C1 and C2 vertebrae, and groups of the existing ligaments were developed. The accurate geometry of the model was obtained from the CT data of a 35-year old male. Three screw constructs were designed to compare; Magerl transarticular screw (TA-Screw), Goel-Harms lateral mass screw and pedicle screw (LM-Screw and Pedicle-Screw), and Wright lateral mass screw and translaminar screw (LM-Screw and TL-Screw). Pure moments were applied to the model in the three main planes; flexion (Flex), extension (Ext), axial rotation (AR) and lateral bending (LB). The range of motion (ROM) of C0-C1 and C1-C2 segments for the implanted FE models are compared to the intact FE model and the in vitro study of Panjabi (1988). The Magerl technique showed less effect on the ROM of C0-C1 than the other two techniques in sagittal plane. In lateral bending and axial rotation, the Goel-Harms and Wright techniques showed less effect on the ROM of C0-C1 than the Magerl technique. The Magerl technique has the highest fusion rate as 99% in all loading directions for the C1-C2 segment. The Wright technique has the lowest fusion rate in LB as 79%. The three techniques resulted in the same fusion rate in extension loading as 99%. The maximum stress for the Magerl technique is the lowest in all load direction compared to other two techniques. The maximum stress in all direction was 234 Mpa and occurred in flexion with the Wright technique. The maximum stress for the Goel-Harms and Wright techniques occurred in lateral mass screw. The ROM obtained from the FE results support this idea that the fusion rate of the Magerl is more than 99%. Moreover, the maximum stress occurred in each screw constructs proves the less failure possibility for the Magerl technique. Another advantage of the Magerl technique is the less number of components compared to other techniques using screw constructs. Despite the benefits of the Magerl technique, there are drawbacks to using this method such as reduction of the C1 and C2 before screw placement. Therefore, other fixation methods such as Goel-Harms and Wright techniques find the solution for the drawbacks of the Magerl technique by adding screws separately to C1 and C2. The FE model implanted with the Wright technique showed the highest maximum stress almost in all load direction.

Keywords: cervical spine, finite element model, atlantoaxial, fixation technique

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Authors: Martin Van, Mohammed Javed, Sarah Hemington-Gorse

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Aim: Our aim was to determine the effect of size and tumor depth of basal cell carcinomas (BCCs) on surgical margin clearance. Methods: A retrospective study was conducted at the Welsh Centre for Burns and Plastic Surgery (WCBPS), Morriston Hospital between 1 Jan 2016 – 31 July 2016. Only patients with confirmed BCC on histopathological analysis were included. Patient data including anatomical region treated, lesion size, histopathological clearance margins and histological sub-types were recorded. An independent T-test was performed determine statistical significance. Results: A total of 228 BCCs were excised in 160 patients. Eleven lesions (4.8%) were incompletely excised. The nose area had the highest rate of incomplete excision. The mean diameter of incompletely excised lesions was 11.4mm vs 11.5mm in completely excised lesions (p=0.959) and the mean histological depth of incompletely excised lesions was 4.1mm vs. 2.5mm for completely excised BCCs (p < 0.05). Conclusions: BCC tumor depth of > 4.1 mm was associated with high rate of incomplete margin clearance. Hence, in prospective patients, a BCC tumor depth (>4 mm) on tissue biopsy should alert the surgeon of potentially higher risk of incomplete excision of lesion.

Keywords: basal cell carcinoma, excision margins, plastic surgery, treatment

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Authors: El Hassan Abba, Touria Hachi, Mhamed Khaffou, Nezha El Adel, Abdelkhalek Zraouti, Hassan ElIdrissi

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The present study has the overall objective of studying the effect of garlic and Argan oil on the growth of Rainbow trout (Oncorhynchus mykiss) fingerlings at the Ras El Ma (Azrou) salmon farming station during the 2023 production period. The fingerlings were distributed in seven tanks at a rate of 1000 per lot. The first control tank (B0) received only the feed without additives. Tanks B1, B2, B3, and B4 received garlic as a feed additive at a rate of 1%, 1.5%, 2% and 2.5% respectively. The fingerlings in tanks B5 and B6, in addition to 2.5% garlic, received 5 and 10ml argon oil, respectively. During this two-month experiment, the weight growth of the fingerlings and the physico-chemical parameters of the water that are favorable for fry rearing (hydrogen potential, temperature, dissolved oxygen, and electrical conductivity) were monitored. The weight growth of fingerlings receiving garlic was positive (mean weight: 4.95g, 5.43g, 5.13g, and 5.06g) compared with control fingerlings (mean weight: 3.88g). The maximum average weight was obtained with 1.5% garlic (average weight: 5.43g). The addition of 5 and 10ml of argon oil to B5 and B6 resulted in a slight increase in weight for the B5 fingerlings (5.37g) compared with the B4 control fingerlings (mean weight: 5.06g) but a minor decrease for the B6 batch (4.73g). The experimental results showed that the use of these feed additives had a positive effect on growth and yield, regardless of the quantities used.

Keywords: Oncorhychus mykiss, fry, feed additive, garlic, argon oil, weight growth

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Authors: Jocelyn Doucet, Jean-Philippe Laviolette, Ali Eslami

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The end-of-life management and recycling of polymer wastes remains a key environment issue in on-going efforts to increase resource efficiency and attaining GHG emission reduction targets. Half of all the plastics ever produced were made in the last 13 years, and only about 16% of that plastic waste is collected for recycling, while 25% is incinerated, 40% is landfilled, and 19% is unmanaged and leaks in the environment and waterways. In addition to the plastic collection issue, the UN recently published a report on chemicals in plastics, which adds another layer of challenge when integrating recycled content containing toxic products into new products. To tackle these important issues, innovative solutions are required. Chemical recycling of plastics provides new complementary alternatives to the current recycled plastic market by converting waste material into a high value chemical commodity that can be reintegrated in a variety of applications, making the total market size of the output – virgin-like, high value products - larger than the market size of the input – plastic waste. Access to high-quality feedstock also remains a major obstacle, primarily due to material contamination issues. Pyrowave approaches this challenge with its innovative nano-recycling technology, which purifies polymers at the molecular level, removing undesirable contaminants and restoring the resin to its virgin state without having to depolymerise it. This breakthrough approach expands the range of plastics that can be effectively recycled, including mixed plastics with various contaminants such as lead, inorganic pigments, and flame retardants. The technology allows yields below 100ppm, and purity can be adjusted to an infinitesimal level depending on the customer's specifications. The separation of the polymer and contaminants in Pyrowave's nano-recycling process offers the unique ability to customize the solution on targeted additives and contaminants to be removed based on the difference in molecular size. This precise control enables the attainment of a final polymer purity equivalent to virgin resin. The patented process involves dissolving the contaminated material using a specially formulated solvent, purifying the mixture at the molecular level, and subsequently extracting the solvent to yield a purified polymer resin that can directly be reintegrated in new products without further treatment. Notably, this technology offers simplicity, effectiveness, and flexibility while minimizing environmental impact and preserving valuable resources in the manufacturing circuit. Pyrowave has successfully applied this nano-recycling technology to decontaminate polymers and supply purified, high-quality recycled plastics to critical industries, including food-contact compliance. The technology is low-carbon, electrified, and provides 100% traceable resins with properties identical to those of virgin resins. Additionally, the issue of low recycling rates and the limited market for traditionally hard-to-recycle plastic waste has fueled the need for new complementary alternatives. Chemical recycling, such as Pyrowave's microwave depolymerization, presents a sustainable and efficient solution by converting plastic waste into high-value commodities. By employing microwave catalytic depolymerization, Pyrowave enables a truly circular economy of plastics, particularly in treating polystyrene waste to produce virgin-like styrene monomers. This revolutionary approach boasts low energy consumption, high yields, and a reduced carbon footprint. Pyrowave offers a portfolio of sustainable, low-carbon, electric solutions to give plastic waste a second life and paves the way to the new circular economy of plastics. Here, particularly for polystyrene, we show that styrene monomer yields from Pyrowave’s polystyrene microwave depolymerization reactor is 2,2 to 1,5 times higher than that of the thermal conventional pyrolysis. In addition, we provide a detailed understanding of the microwave assisted depolymerization via analyzing the effects of microwave power, pyrolysis time, microwave receptor and temperature on the styrene product yields. Furthermore, we investigate life cycle environmental impact assessment of microwave assisted pyrolysis of polystyrene in commercial-scale production. Finally, it is worth pointing out that Pyrowave is able to treat several tons of polystyrene to produce virgin styrene monomers and manage waste/contaminated polymeric materials as well in a truly circular economy.

Keywords: nanorecycling, nanomaterials, plastic recycling, depolymerization

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Authors: I. L. Ibrahim, A. Mann, B. A. Adam

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This project involved screening for antibacterial activity, phytochemical and mineral properties of Leptadenia hastata by flame photometry. The result of phytochemical screening reveals that the presence of flavonoids, tannins, saponins, alkaloids, steroidal, and anthraquinones while the cardiac glycoside was absent. This justifies the plant been used as anti-bleeding and anti-inflammatory agents. The result of flame photometry revealed that 1.85 % (Na), 0.65% (K) and 1.85 % (Ca) which indicates the safe nature of the plant extract as such could be used to lower high blood pressure. The antibacterial properties of both the aqueous and ethanolic extract were studied against some bacteria, Escherichia coli, Bacillus Cercus, Pseudomonas aeruginas, and Enterobacter aerogegens, by disc diffusion method and the result reveals that there are very good activities against the organism while the ethanolic extract at concentration 1.0 – 1.2 mg/ml. the ethanolic extract showed in considerable zone inhibition against bacteria’s; Escherichia coli, Bacillus Cercus, pseudomonas aeruginosa andklebsellapnemuoniae. Minimum inhibitory concentration (MIC) and minimum Bacterial concentration (MBC) were conducted with fairly good significant effect of inhibition on the organism, therefore, plant extract could be a potential source of antibacterial agent.

Keywords: antibacterial activity, Leptadenia hastata, infectious diseases, phytochemical screening

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Authors: A. Rajesh Kanna, G. Suresh Kumar, Sathyanaryana N. Gummadi

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There are various sources of energies available worldwide and among them, crude oil plays a vital role. Oil recovery is achieved using conventional primary and secondary recovery methods. In-order to recover the remaining residual oil, technologies like Enhanced Oil Recovery (EOR) are utilized which is also known as tertiary recovery. Among EOR, Microbial enhanced oil recovery (MEOR) is a technique which enables the improvement of oil recovery by injection of bio-surfactant produced by microorganisms. Bio-surfactant can retrieve unrecoverable oil from the cap rock which is held by high capillary force. Bio-surfactant is a surface active agent which can reduce the interfacial tension and reduce viscosity of oil and thereby oil can be recovered to the surface as the mobility of the oil is increased. Research in this area has shown promising results besides the method is echo-friendly and cost effective compared with other EOR techniques. In our research, on laboratory scale we produced bio-surfactant using the strain Pseudomonas putida (MTCC 2467) and injected into designed simple sand packed column which resembles actual petroleum reservoir. The experiment was conducted in order to determine the efficiency of produced bio-surfactant in oil recovery. The column was made of plastic material with 10 cm in length. The diameter was 2.5 cm. The column was packed with fine sand material. Sand was saturated with brine initially followed by oil saturation. Water flooding followed by bio-surfactant injection was done to determine the amount of oil recovered. Further, the injection of bio-surfactant volume was varied and checked how effectively oil recovery can be achieved. A comparative study was also done by injecting Triton X 100 which is one of the chemical surfactant. Since, bio-surfactant reduced surface and interfacial tension oil can be easily recovered from the porous sand packed column.

Keywords: bio-surfactant, bacteria, interfacial tension, sand column

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Authors: Oyindamola Kayode, Sarah George, Roberto Borrageiro, Mike Shirran

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A phenomenon identified by our industrial partner has experienced sag on AA3104 can body stock (CBS) transfer bar during transportation of the slab from the breakdown mill to the finishing mill. Excessive sag results in bottom scuffing of the slab onto the roller table, resulting in surface defects on the final product. It has been found that increasing the strain rate on the breakdown mill final pass results in a slab resistant to sag. The creep response for materials hot deformed at different Zener–Holloman parameter values needs to be evaluated experimentally to gain better understanding of the operating mechanism. This study investigates this identified phenomenon through laboratory simulation of the breakdown mill conditions for various strain rates by utilizing the Gleeble at UCT Centre for Materials Engineering. The experiment will determine the creep response for a range of conditions as well as quantifying the associated material microstructure (sub-grain size, grain structure etc). The experimental matrices were determined based on experimental conditions approximate to industrial hot breakdown rolling and carried out on the Gleeble 3800 at the Centre for Materials Engineering, University of Cape Town. Plane strain compression samples were used for this series of tests at an applied load that allow for better contact and exaggerated creep displacement. A tantalum barrier layer was used for increased conductivity and decreased risk of anvil welding. One set of tests with no in-situ hold time was performed, where the samples were quenched after deformation. The samples were retained for microstructure analysis of the micrographs from the light microscopy (LM), quantitative data and images from scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), sub-grain size and grain structure from electron back scattered diffraction (EBSD).

Keywords: aluminium alloy, can-body stock, hot rolling, creep response, Zener-Hollomon parameter

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Authors: Anwar Hasan Abdullah Othman, Ahamed Kameel, Hasanuddeen Abdul Aziz

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In this study, an attempt has been made to investigate the relationship specifically the causal relation between fund unit prices of Islamic equity unit trust fund which measure by fund NAV and the selected macro-economic variables of Malaysian economy by using VECM causality test and Granger causality test. Monthly data has been used from Jan, 2006 to Dec, 2012 for all the variables. The findings of the study showed that industrial production index, political election and financial crisis are the only variables having unidirectional causal relationship with fund unit price. However, the global oil prices is having bidirectional causality with fund NAV. Thus, it is concluded that the equity unit trust fund industry in Malaysia is an inefficient market with respect to the industrial production index, global oil prices, political election and financial crisis. However, the market is approaching towards informational efficiency at least with respect to four macroeconomic variables, treasury bill rate, money supply, foreign exchange rate and corruption index.

Keywords: fund unit price, unit trust industry, Malaysia, macroeconomic variables, causality

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Authors: Adnan I. O. Zaid, Hebah B. Melhem, Ahmad Qandil

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The main function of a lubricant in any forming process is to reduce friction between the work piece and the die set, hence reducing the force and energy requirement for forming process and to achieve homogeneous deformation. The free upsetting test is an important open forging test. In this paper, super plastic tin-lead alloy is used as solid lubricant in the free upsetting test of non-ferrous metals and compared with eight different lubricants using the following three criteria: one comparing the value of the reduction in height percentages, i.e. the engineering strain, in identical specimens of the same material under the effect of the same compressive force. The second is comparing the amount of barreling produced in each of the identical specimens, at each lubricant. The third criterion is using the specific energy, i.e. the energy per unit volume consumed in forming each material, using the different lubricants to produce the same reduction in height percentage of identical specimens from each of the two materials, namely: aluminum and brass. It was found that the super plastic tin-lead alloy lubricant has produced higher values of reductions in height percentage and less barreling in the two non-ferrous materials, used in this work namely: aluminum and brass. It was found that the super plastic tin-lead alloy lubricant has produced higher values of reductions in height percentage and less barreling in the two non-ferrous materials, used in this work, under the same compression force among the different used lubricants.

Keywords: aluminum, brass, different lubricants, free upsetting, solid lubricants, superplastic tin-lead alloy

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Authors: Ali Safari, Pejman Hosseiniun, Iman Rahbari, MohamadReza Kalhor

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The semiconductor industry is placing an increased emphasis on emerging materials and devices that may provide improved performance, or provide novel functionality for devices. Recently, graphene, as a true two-dimensional carbon material, has shown fascinating applications in electronics. In this paper detailed discussions are introduced for possible applications of grapheme Transistor in RF and digital devices.

Keywords: graphene, GFET, RF, digital

Procedia PDF Downloads 346

Authors: Velázquez Alejandro, Pradhan Sujan, Yoon Rokhyun, Sanada Yasushi

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The utilization of new materials as an alternative solution to decrease the environmental impact of the construction industry has been gaining more relevance in the architectural design and construction industry. One such material is cross-laminated timber (CLT), an engineered timber solution that excels for its faster construction times, workability, lightweight, and capacity for carbon storage. This material is usually used alone for the entire structure or combined with steel frames, but a hybrid with reinforced concrete (RC) is rarer. Since RC is one of the most used materials worldwide, a hybrid with CLT would allow further utilization of the latter, and in the process, it would help reduce the environmental impact of RC construction to achieve a sustainable society, but first, the structural performance of such hybrids must be understood. This paper focuses on proposing a model to predict the seismic performance of RC frames with CLT panels as infills. A series of static horizontal cyclic loading experiments were conducted on two 40% scale specimens of reinforced concrete frames with and without CLT panels at Osaka University, Japan. An analytical model was created to simulate the seismic performance of the RC frame with CLT infill based on the experimental results. The proposed model was verified by comparing the experimental and analytical results, showing that the load-deformation relationship and the failure mechanism agreed well with limited error. Hence, the proposed analytical model can be implemented for the seismic performance evaluation of the RC frames with CLT infill.

Keywords: analytical model, multi spring, performance evaluation, reinforced concrete, rocking mechanism, wooden wall

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Authors: India Sanders, Jeffrey Sherman

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Colorism has been a persistent and ingrained issue in the history of the United States, with far-reaching consequences that continue to affect various aspects of daily life, institutional policies, public spaces, economic structures, and social norms. This complex problem has had a particularly profound impact on the African-American community, shaping how they are perceived and treated within society at large. The prevalence of negative stereotypes surrounding African Americans can lead to severe repercussions such as discrimination and mental health disparities. The effects of such biases can also materialize in diverse forms, impacting the well-being and livelihoods of individuals within this community. Current research has examined how people from different racial groups perceive different skin tones of Black people, looking at the cognitive processes that manifest through categorization and stereotypes. Additionally, studies observed consequences related to colorism and how it directly affects those with darker versus lighter skin tones. However, not much research has been conducted on the influence of stereotypes associated with various skin tones. In the present study, it is hypothesized that participants in Group A will rate positive stereotypes associated with lighter skin tones significantly higher than positive stereotypes associated with darker skin tones. It is also hypothesized that participants in Group B will rate negative stereotypes associated with darker skin tones significantly higher than negative stereotypes associated with lighter skin tones. For this study, a quantitative study on stereotypes of skin tone representation within the African-American community will be conducted. Participants will rate the accuracy of various visual representations within mass media of African Americans with light skin tones and dark skin tones using a Likert scale. Participants will also be provided a questionnaire further examining the perception of stereotypes and how this affects their interactions with African Americans with lighter versus darker skin tones. The purpose of this study is to investigate the impact of skin tone portrayals on African Americans, including associated stereotypes and societal perceptions. It is expected that participants will more likely associate negative stereotypes with African Americans who have darker skin tones, as this is a common and reinforced viewpoint in the cultural and social system.

Keywords: colorism, discrimination, racism, stereotype

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Authors: Songul Aktas, Turkan Pasinlioglu, Kiymet Yesilcicek Calik

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Introduction: Emphatic approach during labor increases both quality of care and birth satisfaction of mothers. Besides; maternal satisfaction statements and expressions about midwives who assist labor contribute to a positive birth perception and wish to give vaginal delivery again. Aim: The study aimed at investigating the effect of empathy training given to midwives on mothers’ satisfaction with midwives and their birth perception. Material/Method: This experimental study was undertaken between February 2013 and January 2014 at a public hospital in Trabzon Province. The population of the study was composed of mothers who gave vaginal delivery and the sample was composed of 222 mothers determined with power analyzes. Ethical approval and written informed consents were obtained. Mothers who were assisted by midwives during 1st, 2nd and 3rd phases of delivery and first two postpartum hours were included. Empathy training given to midwives included didactic narration, creative drama, psychodrama techniques and lasted 32 hours. The data were collected before the empathy training (BET), right after empathy training (RAET) and 8 weeks later after birth (8WLAB). Mothers were homogenous in terms of socio-demographic, obstetric characteristics. Data were collected with a questionnaire and were analyzed with Chi-square tests. Findings: Rate of mother’s satisfaction with midwives was 36.5% in BET, 81.1% in RAET and 75.7% in 8WLAB. Key mother’s satisfaction with midwives were as follows: 27.6% of mothers told that midwives were “smiling-kind” in BET, 39.6% of them in RAET and 33.7% of them in 8WLAB; 31% of mothers told that midwives were “understanding” in BET, 38.2% of them in RAET and 33.7% of them in 8WLAB; 15.7% of mothers told that midwives were “reassuring” in BET, 44.9% of them in RAET and 39.3% of them in 8WLAB;19.5% of mothers told that midwives were “encouraging and motivating” in BET, 39.8% of them in RAET and 19.8% of mothers told that midwives were “informative” in BET, 45.6% of them in RAET and 35.1% of them in 8WLAB (p<0.05). Key mother’s dissatisfaction with midwives were as follows: 55.3% of mothers told that midwives were “poorly-informed” in BET, 17% of them in RAET and 27.7% of them in 8WLAB; 56.9% of mothers told that midwives were “poorly-listening” in BET, 17.6% of them in RAET and 25.5% of them in 8WLAB; 53.2% of mothers told that midwives were “judgmental-embarrassing” in BET, 17% of them in RAET and 29.8% of them in 8WLAB; 56.2% of mothers told that midwives had “fierce facial expressions” in BET, 15.6% of them in RAET and 28.1% of them in 8WLAB. Rates of mothers’ perception that labor was “easy” were 8.1% in BET, 21.6% in RAET and 13.5% in 8WLAB and rates of mothers’ perception that labor was “very difficult and tiring” were 41.9% in BET, 5.4% in RAET and 13.5% in 8WLAB (p<0.05). Conclusion: The effect of empathy training given to midwives upon statements that described mothers’ satisfaction with midwives and their birth perception was positive. Note: This study was financially funded by TUBİTAK project with number 113S672.

Keywords: empathy training, labor perception, mother’s satisfaction with midwife, vaginal delivery

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Authors: I. Ben Kaddour, S. Larbaoui

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Since their first synthesis, the Silicoaluminophosphates materials have proved their efficiency as a good adsorbent and catalyst in several environmental and energetic applications. In this work, the photocatalytic hydrogen production from water splitting reactions has been conducted under visible radiations in the presence of a series of iron and/or titanium-containing microporous silico-alumino-phosphates materials synthesized by hydrothermal method, using triethylamine as an organic structuring agent to obtain the AFI structure type. These photo-catalysts were then characterized by various physicochemical methods to determine their structural, textural and morphological properties such as X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) coupled with X rays microanalysis, nitrogen adsorption measurements, UV-visible diffuse reflectance spectroscopy (UV-Vis-DRS), and X-rays photoelectron spectroscopy (XPS) and the analysis revealed that these materials have significant photocatalytic properties. The hydrogen production process has been followed by photoelectrochemical characterization (PEC). The results showed that hydrogen is the only gas produced, and the reaction takes place in the conduction band where water is reduced to hydrogen. The electron recombination has also been avoided, as holes are entrapped using hole scavengers. In addition, these catalysts have been shown to remain stable during reuse for up to five cycles.

Keywords: photocatalysis, SAPO-5, hydrothermal synthesis, hydrogen production

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