Search results for: perception reaction time

Authors: Francis Edum-Fotwe, Tony Thorpe, Charles Afetornu

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Risk perception informs the outcome of how issues are responded to in either solving or overcoming a problem or improving a situation. Risk perception is established to be affected by some key factors reflecting in the varying ways in which work is done as well as the level of efficiency achieved. These factors potentially would influence risk perception to different extents. Such that if these factors are said to determine risk perception, how does a change in any affect risk perception. Since the ability to address risk is influenced by risk perception, establishing and developing awareness of that perception should enable construction professionals to make viable decisions. Any act to improve the construction industry cannot be overemphasised, considering its contribution to national development. A survey questionnaire was conducted in Ghana to elicit data that measures the risk perception and the essential factors as well as the necessary demographics of the respondents, who are construction professionals. This study finds out the sensitivity of the critical factors of risk perception. It uses the Relative Importance Index analysis tool to investigate the differential effect of these essential factors on risk perception, such that a slight change in a factor makes a significant change in risk perception, having established that it is influenced by essential factors. The findings can lead to policy formation for employers on the prioritisation factors to undertake to improve the risk perception of employees. Other areas in which this study can be useful in team formation for sensitive and complex projects where efficient risk management is critical.

Keywords: construction industry, risk, risk management, risk perception

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Authors: E. Moroydor Derun, P. Gurses, M. Yildirim, A. S. Kipcak, T. Ibroska, S. Piskin

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Due to their strong mechanical and thermal properties magnesium borates have a wide usage area such as ceramic industry, detergent production, friction reducing additive and grease production. In this study, microwave synthesis of magnesium borates from MgCl2.6H2O (Magnesium chloride hexahydrate), MgO (Magnesium oxide) and H3BO3 (Boric acid) for different reaction times is researched. X-ray Diffraction (XRD) and Fourier Transform Infrared (FT-IR) Spectroscopy are used to find out how the reaction time sways on the products. The superficial properties are investigated with Scanning Electron Microscopy (SEM). According to XRD analysis, the synthesized compounds are 00-041-1407 pdf coded Shabinite (Mg5(BO3)4Cl2(OH)5.4(H2O)) and 01-073-2158 pdf coded Karlite (Mg7(BO3)3(OH,Cl)5).

Keywords: magnesium borate, microwave synthesis, XRD, SEM

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Authors: Muhammad Abdullahi Mago

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Islamic Banking began in Nigeria last three years and the sector has shown the sign of bright future for the sector and the Nigerian economy, within this very short time it is important to know the perception of the customers particularly learned or educated individuals for immediate evaluation and adjustment. This study investigates into the perception, awareness and attitudes of the academicians in the most populous state/place in Nigeria with more than 90% muslims, and the results has shown a relatively low levels results in all the variables of the study.The study recommends aggressive marketing strategy for the Banks operating within the sector.

Keywords: Islamic Banking Products, Islamic Financial Products, academicians, Islamic finance industry, perception, awareness and attitude

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Authors: Lu Zhao, Nadir Farhi, Zoi Christoforou, Nadia Haddadou

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The safety test of deploying intelligent connected vehicles (ICVs) on the road network is a critical challenge. Road traffic network simulation can be used to test the functionality of ICVs, which is not only time-saving and less energy-consuming but also can create scenarios with car collisions. However, the relationship between different human driver behaviors and the car-collision occurrences has been not understood clearly; meanwhile, the procedure of car-collisions generation in the traffic numerical simulators is not fully integrated. In this paper, we propose an approach to identify specific driver profiles from real driven data; then, we replicate them in numerical traffic simulations with the purpose of generating inter-vehicular collisions. We proposed three profiles: (i) 'aggressive': short time-headway, (ii) 'inattentive': long reaction time, and (iii) 'normal' with intermediate values of reaction time and time-headway. These three driver profiles are extracted from the NGSIM dataset and simulated using the intelligent driver model (IDM), with an extension of reaction time. At last, the generation of inter-vehicular collisions is performed by varying the percentages of different profiles.

Keywords: vehicular collisions, human driving behavior, traffic modeling, car-following models, microscopic traffic simulation

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Authors: Evgeny Kozubenko, Dmitry Shaposhnikov, Mikhail Petrushan

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This work is focused on the study of the binocular characteristics of the phenomenon of perisaccadic suppression in humans when perceiving visual objects. This phenomenon manifests in a decrease in the subject's ability to perceive visual information during saccades, which play an important role in purpose-driven behavior and visual perception. It was shown that the impairment of perception of visual information in the post-saccadic time window is stronger (p < 0.05) in the ipsilateral eye (the eye towards which the saccade occurs). In addition, the observed heterogeneity of post-saccadic suppression in the contralateral and ipsilateral eyes may relate to depth perception. Taking the studied phenomenon into account is important when developing ergonomic control panels in modern operator systems.

Keywords: eye movement, natural vision, saccadic suppression, visual perception

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Authors: Samira Gharehkhani, Seyed Farid Seyed Shirazi, Abdolreza Gharehkhani, Hooman Yarmand, Ahmad Badarudin, Rushdan Ibrahim, Salim Newaz Kazi

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Nanocrystalline cellulose (NCC) were prepared by acid hydrolysis and ultrasound treatment of bleached Acacia mangium fibers. The obtained rod-shaped nanocrystals showed a uniform size. The results showed that NCC with high crystallinity can be obtained using 64 wt% sulfuric acid. The effect of synthesis condition was investigated. Different reaction times were examined to produce the NCC and the results revealed that an optimum reaction time has to be used for preparing the NCC. Morphological investigation was performed using the transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) were performed. X-ray diffraction (XRD) analysis revealed that the crystallinity increased with successive treatments. The NCC suspension was homogeneous and stable and no sedimentation was observed for a long time.

Keywords: acid hydrolysis, nanocrystalline cellulose, nano material, reaction time

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Authors: Velid Demir, Mesut Akgün

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The lanthanum and zinc oxide were synthesized and then loaded with 6 wt% over γ-Al₂O₃ using the wet impregnation method. The samples were calcined at 900 °C to ensure a coherent structure with high catalytic performance. Characterization of the catalysts was verified by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The effect of catalysts on biodiesel content from jatropha oil was studied under supercritical conditions. The results showed that ZnO/γ-Al₂O₃ was the superior catalyst for jatropha oil with 98.05% biodiesel under reaction conditions of 7 min reaction time, 1:40 oil to methanol molar ratio, 6 wt% of catalyst loading, 90 bar of reaction pressure, and 300 °C of reaction temperature, compared to 95.50% with La₂O₃/γ-Al₂O₃ at the same parameters. For this study, ZnO/γ-Al₂O₃ was the most suitable catalyst due to performance and cost considerations.

Keywords: biodiesel, heterogeneous catalyst, jatropha oil, supercritical methanol, transesterification

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Authors: S. Haider, B. Bhushan

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Eye Gaze behaviour of individuals with and without intellectual disability are investigated in an eye tracking study in terms of sensitivity to Nonaccidental (NAPs) and Metric (MPs) shape properties. Total fixation time is used as an indirect measure of attention allocation. Studies have found Mean reaction times for non accidental properties (NAPs) to be shorter than for metric (MPs) when the MP and NAP differences were equalized. METHODS: Twenty-five individuals with intellectual disability (mild and moderate level of Mental Retardation) and twenty-seven normal individuals were compared on mean total fixation duration, accuracy level and mean reaction time for mild NAPs, extreme NAPs and metric properties of images. 2D images of cylinders were adapted and made into forced choice match-to-sample tasks. Tobii TX300 Eye Tracker was used to record total fixation duration and data obtained from the Areas of Interest (AOI). Variable trial duration (total reaction time of each participant) and fixed trail duration (data taken at each second from one to fifteen seconds) data were used for analyses. Both groups did not differ in terms of fixation times (fixed as well as variable) across any of the three image manipulations but differed in terms of reaction time and accuracy. Normal individuals had longer reaction time compared to individuals with intellectual disability across all types of images. Both the groups differed significantly on accuracy measure across all image types. Normal individuals performed better across all three types of images. Mild NAPs vs. Metric differences: There was significant difference between mild NAPs and metric properties of images in terms of reaction times. Mild NAPs images had significantly longer reaction time compared to metric for normal individuals but this difference was not found for individuals with intellectual disability. Mild NAPs images had significantly better accuracy level compared to metric for both the groups. In conclusion, type of image manipulations did not result in differences in attention allocation for individuals with and without intellectual disability. Mild Nonaccidental properties facilitate better accuracy level compared to metric in both the groups but this advantage is seen only for normal group in terms of mean reaction time.

Keywords: eye gaze fixations, eye movements, intellectual disability, stimulus properties

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Authors: Yildiz Erdoganoglu, Unzile Tunc

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The aim of this study was to determine the relationship of body, upper extremity, lower extremity endurance, and core functionality with body perception and self-esteem in individuals who applied for a bodybuilding exercise program. Forty volunteer male subjects who underwent bodybuilding exercises for one year or more were included in the study. After obtaining demographic information of the individuals, trunk endurance was evaluated by curl-up and modified Sorensen test, upper extremity endurance by push-up test, lower extremity endurance by repeated squat test, core functionalities by single-leg wall sitting and repeated single-leg squatting tests. body perception, body image perception scale, and self-esteem were evaluated with Rosenberg self-esteem scale. The mean age of the individuals was 25.60 ± 4.70 years, mean exercise time was 22.47 ± 34.60 months. At the end of the study, body perception was low, and self-esteem was moderate. There was no significant relationship between abdominal endurance, back extensor endurance, upper extremity, and lower extremity endurance, core functionality, and body perception (p > 0.05). Also, there was no significant relationship between abdominal extensor, back extensor, upper extremity and lower extremity endurance, core functionality, and self-esteem (p > 0.05). The body, upper and lower extremity endurance, and core functionality of bodybuilders did not have any effect on body perception and self-esteem, suggesting that these individuals did not contribute positively to their efforts to improve their body perception and self- esteem.

Keywords: body endurance, body perception, core functionality, self esteem

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Authors: Binyam Teferi

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In this paper, a theoretical analysis of blood flow in the presence of thermal radiation and chemical reaction under the influence of time dependent magnetic field intensity has been studied. The unsteady non linear partial differential equations of blood flow considers time dependent stretching velocity, the energy equation also accounts time dependent temperature of vessel wall, and concentration equation includes time dependent blood concentration. The governing non linear partial differential equations of motion, energy, and concentration are converted into ordinary differential equations using similarity transformations solved numerically by applying ode45. MATLAB code is used to analyze theoretical facts. The effect of physical parameters viz., permeability parameter, unsteadiness parameter, Prandtl number, Hartmann number, thermal radiation parameter, chemical reaction parameter, and Schmidt number on flow variables viz., velocity of blood flow in the vessel, temperature and concentration of blood has been analyzed and discussed graphically. From the simulation study, the following important results are obtained: velocity of blood flow increases with both increment of permeability and unsteadiness parameter. Temperature of the blood increases in vessel wall as Prandtl number and Hartmann number increases. Concentration of the blood decreases as time dependent chemical reaction parameter and Schmidt number increases.

Keywords: stretching velocity, similarity transformations, time dependent magnetic field intensity, thermal radiation, chemical reaction

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Authors: Allah Bakhsh Javid, Ali Mashayekh-Salehi, Fatemeh Davardoost

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This study presents the preparation, characterization and catalytic activity of a novel natural mineral-based catalyst for destructive adsorption of tetracycline (TTC) as water emerging compounds. Degradation potential of raw and calcined magnetite catalyst was evaluated at different experiments situations such as pH, catalyst dose, reaction time and pollutant concentration. Calcined magnetite attained greater catalytic potential than the raw ore in the degradation of tetracycline, around 69% versus 3% at reaction time of 30 min and TTC aqueous solution of 50 mg/L, respectively. Complete removal of TTC could be obtained using 2 g/L calcined nanoparticles at reaction time of 60 min. The removal of TTC increased with the increase in solution temperature. Accordingly, considering its abundance in nature together with its very high catalytic potential, calcined pyrite is a promising and reliable catalytic material for destructive decomposition for catalytic decomposition and mineralization of such pharmaceutical compounds as TTC in water and wastewater.

Keywords: catalytic degradation, tetracycline, pyrite, emerging pollutants

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Authors: Arnaldo G. de Oliveira, Jr, Matthieu Tubino

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The transesterification process of triglycerides with alcohols that occurs during the biodiesel synthesis causes continuous changes in several physical properties of the reaction mixture, such as refractive index, viscosity and density. Amongst them, density can be an useful parameter to monitor the reaction, in order to predict the composition of the reacting mixture and to verify the conversion of the oil into biodiesel. In this context, a system was constructed in order to continuously determine changes in the density of the reacting mixture containing soybean oil, methanol and sodium methoxide (30 % w/w solution in methanol), stirred at 620 rpm at room temperature (about 27 °C). A polyethylene pipe network connected to a peristaltic pump was used in order to collect the mixture and pump it through a coil fixed on the plate of an analytical balance. The collected mass values were used to trace a curve correlating the mass of the system to the reaction time. The density variation profile versus the time clearly shows three different steps: 1) the dispersion of methanol in oil causes a decrease in the system mass due to the lower alcohol density followed by stabilization; 2) the addition of the catalyst (sodium methoxide) causes a larger decrease in mass compared to the first step (dispersion of methanol in oil) because of the oil conversion into biodiesel; 3) the final stabilization, denoting the end of the reaction. This density variation profile provides information that was used to predict the composition of the mixture over the time and the reaction rate. The precise knowledge of the duration of the synthesis means saving time and resources on a scale production system. This kind of monitoring provides several interesting features such as continuous measurements without collecting aliquots.

Keywords: biodiesel, density measurements, online continuous monitoring, synthesis

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Authors: Doo Ki Lee, Kumaresh Selvakumar, Man Young Kim

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Catalytic combustion is an environmentally friendly technique to combust fuels in gas turbines. In this paper, the behavior of surface reaction rate on catalytic combustion is studied with respect to the heterogeneous oxidation of methane-air mixture in a catalytic reactor. Plug flow reactor (PFR), the simplified single catalytic channel assists in investigating the catalytic combustion phenomenon over the Pt catalyst by promoting the desired chemical reactions. The numerical simulation with multi-step elementary surface reactions is governed by the availability of free surface sites onto the catalytic surface and thereby, the catalytic combustion characteristics are demonstrated by examining the rate of the reaction for lean fuel mixture. Further, two different surface reaction mechanisms are adopted and compared for surface reaction rates to indicate the controlling heterogeneous reaction for better fuel conversion. The performance of platinum catalyst under heterogeneous reaction is analyzed under the same temperature condition, where the catalyst with the higher kinetic rate of reaction would have a maximum catalytic activity for enhanced methane catalytic combustion.

Keywords: catalytic combustion, heterogeneous reaction, plug flow reactor, surface reaction rate

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Authors: Anastasiya Paltarzhitskaya

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Subjective time plays an important role in consciousness processes and self-awareness at the moment. The concept of intrinsic neural timescales (INT) explains the difference in perceiving various time intervals. The capacity to experience the present builds on the fundamental properties of temporal cognition. The challenge that both philosophy and neuroscience try to answer is how the brain differentiates the present from the past and future. In our work, we analyze papers which describe mechanisms involved in the perception of ‘present’ and ‘non-present’, i.e., future and past moments. Taking into account that we perceive time intervals even during rest or relaxation, we suppose that the default-mode network activity can code time features, including the present moment. We can compare some results of time perceptual studies, where brain activity was shown in states with different flows of time, including resting states and during “mental time travel”. According to the concept of mental traveling, we employ a range of scenarios which demand episodic memory. However, some papers show that the hippocampal region does not activate during time traveling. It is a controversial result that is further complicated by the phenomenological aspect that includes a holistic set of information about the individual’s past and future.

Keywords: temporal consciousness, time perception, memory, present

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Authors: Kanda Wongwailikhit

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Copper (I) oxide microparticles with the morphology of cubic and hollow sphere were synthesized with the assistance of a surfactant as the shape controller. Both particles were then subjected to a study of the catalytic activity and the results of shape effects of catalysts on rate of catalytic reaction was observed. The decolorizing reaction of crystal violet and sodium hydroxide was chosen and the decrease of reactant with respect to time was measured using a spectrophotometer. The result revealed that morphology of the crystal had no effect on the catalytic activity for the crystal violet reaction but contributed to total surface area predominantly.

Keywords: copper (I) oxide, catalytic activity, crystal violet

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Authors: Juree Hong, Sanggeun Lee, Jungmok Seo, Taeyoon Lee

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We report a facile synthesis of metal nano particles (NPs) on graphene layer via galvanic displacement reaction between graphene-buffered copper (Cu) and metal ion-containing salts. Diverse metal NPs can be formed on graphene surface and their morphologies can be tailored by controlling the concentration of metal ion-containing salt and immersion time. The obtained metal NP-decorated single-layer graphene (SLG) has been used as hydrogen gas (H2) sensing material and exhibited highly sensitive response upon exposure to 2% of H2.

Keywords: metal nanoparticle, galvanic displacement reaction, graphene, hydrogen sensor

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Authors: Triana Fitriastuti, Pipiet Larasatie, Alex Vanderstraten

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Many scholars have demonstrated the negative impacts of the perception of organizational politics on organizational outcomes. The model proposed in this study analyzes the impact of the perception of organizational politics on job satisfaction. In the same way, ingratiation as a moderator variable is tested. We applied regression analysis to test the hypothesis. The findings of the current research, which was conducted with 240 employees in the public sector in Indonesia, show that the perception of organizational politics has a negative effect on job satisfaction. In contrast, ingratiation plays a role that fully moderates the relationship between organizational politics and organizational outcomes and changes the correlation between the perception of organizational politics on job satisfaction. Employees who use ingratiation as a coping mechanism tend to do so when they perceive a high degree of organizational politics.

Keywords: ingratiation, impression management, job satisfaction, perception of organizational politics

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Authors: Burcu Kiren, Alattin CAkan, Nezihe Ayas

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Hydrogen will be arguably the best fuel in the future as it is the most abundant element in the universe. Hydrogen, as a fuel, is notably environmentally benign, sustainable and has high energy content compared to other sources of energy. It can be generated from both conventional and renewable sources. The hydrolysis reaction of metal hydrides provides an option for hydrogen production in the presence of a catalyst. In this study, Ni/dolomite catalyst was synthesized by the wet impregnation method for hydrogen production by hydrolysis reaction of sodium borohydride (NaBH4). Besides, the synthesized catalysts characterizations were examined by means of thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer –Emmett – Teller (BET) and scanning electron microscopy (SEM). The influence of reaction temperature (25-75 °C), reaction time (15-60 min.), amount of catalyst (50-250 mg) and active metal loading ratio (20,30,40 wt.%) were investigated. The catalyst prepared with 30 wt.% Ni was noted as the most suitable catalyst, achieving of 35.18% H₂ and hydrogen production rate of 19.23 mL/gcat.min at 25 °C at reaction conditions of 5 mL of 0.25 M NaOH and 100 mg NaBH₄, 100 mg Ni/dolomite.

Keywords: sodium borohydride, hydrolysis, catalyst, Ni/dolomite, hydrogen

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Authors: Mengxin Feng, Feng Xu, Zhiyong Lai

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As a typical representative of the countryside, traditional Chinese villages are rich in cultural landscape resources and historical information, but they are still in continuous decline. The problems of people's weak protection awareness and low cultural recognition are still serious, and the protection of cultural heritage is imminent. At the same time, with the rapid development of rural tourism, its cultural value has been explored and paid attention to again. From the perspective of tourists, this study aimed to explore people's perception and identity of cultural landscape resources under the current cultural tourism development background. We selected eleven typical landscape elements of Lingshui Village, a traditional village in Beijing, as research objects and conducted a questionnaire survey with two scales of perception and identity to explore the characteristics of people's perception and identification of landscape elements. We found that there was a strong positive correlation between the perception and identity of each element and that geographical location influenced visitors' overall perception. The perception dimensions scored the highest in location, and the lowest in history and culture, and the identity dimensions scored the highest in meaning and lowest in emotion. We analyzed the impact of visitors' backgrounds on people's perception and identity characteristics and found that age and education were two important factors. The elderly had a higher degree of perceived identity, as the familiarity effect increased their attention. Highly educated tourists had more stringent criteria for perception and identification. The above findings suggest strategies for conserving and optimizing landscape elements in the traditional village to improve the acceptance and recognition of cultural information in traditional villages, which will inject new vitality into the development of traditional villages.

Keywords: traditional village, tourist perception, landscape elements, perception and identity

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Authors: Gianluca Del Rossi

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Sub-concussive impacts occur frequently in collision sports such as American tackle football. Sub-concussive level impacts are defined as hits to the head that do not result in the clinical manifestation of concussion injury. Presently, there is limited information known about the short-term effects of repeated sub-concussive blows to the head. Therefore, the purpose of this investigation was to determine if standard clinical measures could detect acute impairments in neurologic function resulting from the accumulation of sub-concussive impacts throughout a season of high school American tackle football. Simple reaction time using the ruler-drop test, and oculomotor performance using the King-Devick (KD) test, were assessed in 15 athletes prior to the start of the athletic season, then repeated each week of the season, and once following its completion. The mean reaction times and fastest KD scores that were recorded or calculated from each study participant and from each test session were analyzed to assess for change in reaction time and oculomotor performance over the course of the American tackle football season. Analyses of KD data revealed improvements in oculomotor performance from baseline measurements (i.e., decreased time), with most weekly comparisons to baseline being significantly different. Statistical tests performed on the mean reaction times obtained via the ruler-drop test throughout the season revealed statistically significant declines (i.e., increased time) between baseline and weeks 3, 4, 10, and 12 of the athletic season. The inconsistent and contrasting findings between KD data and reaction time demonstrate the need to identify more robust clinical measures to definitively assess if repeated sub-concussive impacts to the head are acutely detrimental to patients.

Keywords: head injury, mTBI and sport, subclinical head trauma, sub-concussive impacts

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Authors: Mustafa Sertçelik, Hacali Necefoğlu, Turan Çalban, Soner Kuşlu

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In this study, Chevreul’s salt was dissolved in ammonium chloride solutions. All experiments were performed in a batch reactor. The obtained results were optimized. Parameters used in the experiments were the reaction temperature, the ammonium chloride concentration, the reaction time and the solid-to-liquid ratio. The optimum conditions were determined by 2⁴ factorial experimental design method. The best values of four parameters were determined as based on the experiment results. After the evaluation of experiment results, all parameters were found as effective in experiment conditions selected. The optimum conditions on the maximum Chevreul’s salt dissolution were the ammonium chloride concentration 4.5 M, the reaction time 13.2 min., the reaction temperature 25 ^oC, and the solid-to-liquid ratio 9/80 g.mL^-1. The best dissolution yield in these conditions was 96.20%.

Keywords: Chevreul's salt, factorial experimental design method, ammonium chloride, dissolution, optimization

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Authors: F. A. F. da Ponte, J. Q. Malveira, I. A. Maciel, M. C. G. Albuquerque

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In this work aviation, biofuel production was studied by fatty acids (C6 to C16) esterification. The process variables in heterogeneous catalysis were evaluated using an experimental design. Temperature and reaction time were the studied parameters, and the methyl esters content was the response of the experimental design. An ion exchange resin was used as a heterogeneous catalyst. The process optimization was carried out using response surface methodology (RSM) and polynomial model of second order. Results show that the most influential variables on the linear coefficient of each effect studied were temperature and reaction time. The best result of methyl esters conversion in the experimental design was under the conditions: 10% wt of catalyst; 100 °C and 4 hours of reaction. The best-achieved conversion was 96.5% wt of biofuel.

Keywords: esterification, ion-exchange resins, response surface methodology, biofuel

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Authors: Ratna Dewi Kusumaningtyas, Riris Pristiyani, Heny Dewajani

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Biodiesel is commonly produced via the two main routes, i.e. the transesterification of triglycerides and the esterification of free fatty acid (FFA) using short-chain alcohols. Both the two routes have drawback in term of the side product yielded during the reaction. Transesterification reaction of triglyceride results in glycerol as side product. On the other hand, FFA esterification brings in water as side product. Both glycerol and water in the biodiesel production are managed as waste. Hence, a separation process is necessary to obtain a high purity biodiesel. Meanwhile, separation processes is generally the most capital and energy intensive part in industrial process. Therefore, to reduce the separation process, it is essential to produce biodiesel via an alternative route eliminating glycerol or water side-products. In this work, biodiesel synthesis was performed using a glycerol-free process through chemical interesterification of jatropha oil with ethyl acetate in the presence on sodium acetate catalyst. By using this method, triacetine, which is known as fuel bio-additive, is yielded instead of glycerol. This research studied the effects of catalyst concentration on the jatropha oil interesterification process in the range of 0.5 – 1.25% w/w oil. The reaction temperature and molar ratio of oil to ethyl acetate were varied at 50, 60, and 70°C, and 1:6, 1:9, 1:15, 1:30, and 1:60, respectively. The reaction time was evaluated from 0 to 8 hours. It was revealed that the best yield was obtained with the catalyst concentration of 0.5%, reaction temperature of 70 °C, molar ratio of oil to ethyl acetate at 1:60, at 6 hours reaction time.

Keywords: biodiesel, interesterification, glycerol-free, triacetine, jatropha oil

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Authors: Comfort Mokgothu

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This study investigated the relation between processing information and fitness level of active (fit) and sedentary (unfit) children drawn from rural and urban areas in Botswana. It was hypothesized that fit children would display faster simple reaction time (SRT), choice reaction times (CRT) and movement times (SMT). 60, third grade children (7.0 – 9.0 years) were initially selected and based upon fitness testing, 45 participated in the study (15 each of fit urban, unfit urban, fit rural). All children completed anthropometric measures, skinfold testing and submaximal cycle ergometer testing. The cognitive testing included SRT, CRT, SMT and Choice Movement Time (CMT) and memory sequence length. Results indicated that the rural fit group exhibited faster SMT than the urban fit and unfit groups. For CRT, both fit groups were faster than the unfit group. Collectively, the study shows that the relationship that exists between physical fitness and cognitive function amongst the elderly can tentatively be extended to the pediatric population. Physical fitness could be a factor in the speed at which we process information, including decision making, even in children.

Keywords: decision making, fitness, information processing, reaction time, cognition movement time

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Authors: L. Parisi

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In this research work, neural networks were applied to classify two types of hip joint implants based on the relative hip joint implant side speed and three components of each ground reaction force. The condition of walking gait at normal velocity was used and carried out with each of the two hip joint implants assessed. Ground reaction forces’ kinetic temporal changes were considered in the first approach followed but discarded in the second one. Ground reaction force components were obtained from eighteen patients under such gait condition, half of which had a hip implant type I-II, whilst the other half had the hip implant, defined as type III by Orthoload®. After pre-processing raw gait kinetic data and selecting the time frames needed for the analysis, the ground reaction force components were used to train a MLP neural network, which learnt to distinguish the two hip joint implants in the abovementioned condition. Further to training, unknown hip implant side and ground reaction force components were presented to the neural networks, which assigned those features into the right class with a reasonably high accuracy for the hip implant type I-II and the type III. The results suggest that neural networks could be successfully applied in the performance assessment of hip joint implants.

Keywords: kinemic gait data, neural networks, hip joint implant, hip arthroplasty, rehabilitation engineering

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Authors: Sang-Woo Han, Jong-Shik Shin

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w-Transaminase (w-TA) is broadly used for synthesizing chiral amines with a high enantiopurity. However, the reaction mechanism of w-TA has been not well studied, contrary to a-transaminase (a-TA) such as AspTA. Here, we propose in silico model on the reaction mechanism of w-TA. Based on the modeling results which showed large free energy gaps between external aldimine and quinonoid on deamination (or ketimine and quinonoid on amination), withdrawal of Ca-H seemed as a critical step which determines the reaction rate on both amination and deamination reactions, which is consistent with previous researches. Hyperconjugation was also observed in both external aldimine and ketimine which weakens Ca-H bond to elevate Ca-H abstraction.

Keywords: computational modeling, reaction intermediates, w-transaminase, in silico model

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Authors: Saadet Akbay, Ayşe Nihan Avcı

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The perception of colour is a subjective experience which depends on age, gender, race, cultural and educational backgrounds, etc. of an individual. However, colour perception is also affected by the correlated colour temperature (CCT) of a light source which is considered as one of the most fundamental quantitative lighting characteristics. This study focuses on evaluating colour perception in different CCT of light emitting diodes (LED) lighting. The aim is to compare the inherent colours with the perceived colours under two CCT of ‘warm’ (2700K), and ‘cool’ (4000K) LED lights and to understand how different CTT affect the perception of a colour. Analysis and specifications of colour attributes are made with Natural Colour System (NCS) which is an international colour communication system. The outcome of the study reveals the possible tendencies for perceived colours under different illuminance levels of LED lighting.

Keywords: colour perception, correlated colour temperature, inherent and perceived colour, LED lighting, natural colour system (NCS)

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Authors: Vinaya Kambappa

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Propylphosphonic anhydride (T3P®)-DMSO is used as an efficient and mild reagent for the one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones from aromatic alcohols. Alcohols are oxidized in situ to aldehydes under mild conditions, which in turn undergo a three-component reaction with β-ketoester and urea/thiourea to afford 3,4-dihydropyrimidin-2(1H)-ones/thiones. The synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones directly from alcohols has been reported for the first time best to our knowledge, under mild reaction conditions in good yield. The easy work-up procedure, low cost and less toxicity of the reagent are the main advantages of this protocol.

Keywords: β-ketoester, propylphosphonic anhydride, three-component reaction, pyrimidine

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Authors: Ude N. Callistus, Amulu F. Ndidi, Onukwuli D. Okechukwu, Amulu E. Patrick

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Power law approximation was used in this study to evaluate the reaction orders of calcium oxide, CaO catalyzed transesterification of refined cottonseed oil and methanol. The kinetics study was carried out at temperatures of 45, 55 and 65 ^oC. The kinetic parameters such as reaction order 2.02 and rate constant 2.8 hr^-1g^-1cat, obtained at the temperature of 65 ^oC best fitted the kinetic model. The activation energy, Ea obtained was 127.744 KJ/mol. The results indicate that the transesterification reaction of the refined cottonseed oil using calcium oxide catalyst is approximately second order reaction.

Keywords: refined cottonseed oil, transesterification, CaO, heterogeneous catalysts, kinetic model

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Authors: Silvana Caglieri

Abstract:

Theoretical study of acetylation of p-methylaniline catalyzed by Cu2+ ions from the analysis of intermediate of the reaction was carried out. The study of acetylation of amines is of great interest by the utility of its products of reaction and is one of the most frequently used transformations in organic synthesis as it provides an efficient and inexpensive means for protecting amino groups in a multistep synthetic process. Acetylation of amine is a nucleophilic substitution reaction. This reaction can be catalyzed by Lewis acid, metallic ion. In reaction mechanism, the metallic ion formed a complex with the oxygen of the acetic anhydride carbonyl, facilitating the polarization of the same and the successive addition of amine at the position to form a tetrahedral intermediate, determining step of the rate of the reaction. Experimental work agreed that this reaction takes place with the formation of a tetrahedral intermediate. In the present theoretical work were investigated the structure and energy of the tetrahedral intermediate of the reaction catalyzed by Cu2+ ions. Geometries of all species involved in the acetylation were made and identified. All of the geometry optimizations were performed by the method at the DFT/B3LYP level of theory and the method MP2. Were adopted the 6-31+G* basis sets. Energies were calculated using the Mechanics-UFF method. Following the same procedure it was identified the geometric parameters and energy of reaction intermediate. The calculations show 61.35 kcal/mol of energy for the tetrahedral intermediate and the energy of activation for the reaction was 15.55 kcal/mol.

Keywords: amides, amines, DFT, MP2

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