Search results for: prepared meter

Authors: Ricardo Chaves, Carlos Vasconcelos

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Candidates to join the Naval Academy have to take a set of physical tests, which is crucial for a high level of physical fitness. Thus, the planning of physical exercises for candidates to the Naval School must take into account the improvement of their physical fitness. The aim of this study was to investigate the impact of a 6-month exercise program to improve the physical fitness of an individual who will apply for the Naval Academy. This was a non-experimental pre-post-evaluation study. The patient was male, had 18 years old, and a body mass index of 21.1 kg.m². The patient participated in a 6-month aerobic and strength exercise program (3 sessions per week, 75 minutes duration each session). Physical fitness tests were performed according to the physical fitness requirements for entry into the Naval academy (muscle strength [maximum number of lifts and maximum number of sit-ups for 1 minute]; aerobic fitness [2.4 km run and 200 m swimming test]) before (baseline) and after the exercise intervention (6 months). Regarding muscle strength, in the abdominal test, the improvements between the pre-test (39 abdominals.) and post-test (61 abdominals) were 56.4%. For elevations, there was an increase in its number by 150% between the pre-test (4 elevations) and post-test (10 elevations). With regard to aerobic fitness, in the 2.4 km race, there was an evolution of 32.0% between the pre-test (16.46 min.) and the post-test (12.42 min.). For the 200-meter swimming test, there was a negative variation of 2% between the pre-test (2.25 min.) and post-test (2.28 min). A 6-month aerobic and strength exercise program leads to a positive evolution in the muscular strength of the patient. Regarding aerobic fitness, opposite results were found, with a positive evolution in the 2.4 km running test and a negative evolution in the swimming test. In future exercise programs for the improvement of the physical fitness of candidates for the Naval Academy, more emphasis has to be done on specific swimming training.

Keywords: case study, exercise program, Naval Academy, physical fitness

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Authors: Muhammad Naziru Yahaya, Mustapha Bashir Ayinde

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Noise has been recognized as a major source of pollution in many urban and semi-urban settlements. Noise pollution causes by vehicular movement in urban cities has reaches an alarming proportion due to continuous increases in vehicles and industrialization. This research aim to determine the geo-physical characteristics of the study area and to determine the level of noise generation and volume intensity in areas where noise levels are high within the metropolis and compare with NESREA and WHO standards. This study identified the various sources of noise, compared noise levels in various parts of the study area with recommended standards and determined the geo-physical characteristic of noise generated. A sound level meter Gm 1352, was used for the noise measurements. The study showed that the noise pollution levels measured in minimum noise level of 63.75 dBA and average maximum of 95.175 dBA, at some locations in Birnin Kebbi metropolis the noise level have exceeded the standard limits set by the World Health Organization (WHO), Federal Environment Protection Agency (FEPA). Results revealed that there was a considerable increase in noise pollution in First Bank roundabout and Haliru Abdu roundabout, attribute to high numbers of vehicular movement and road congestion within Birnin Kebbi. The study therefore concluded that there should be an enforcement and adherence to the regulation regarding noise pollution limit. The minimum average day noise level recorded was 67.225 dBA, and average maximum of 96.6 dBA is an indication that the noise level of Birnin Kebbi metropolis was highly unsatisfactory. Based on this, it is suggested that taking adequate measures and following the laid-down recommendations will reduce traffic noise to the barest minimum.

Keywords: decibel, noise level, pollution, sound level, traffic, highway

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Authors: Rasheed Amao Busari, Ahmed Ibrahim

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The engineering properties of giant palms are crucial for the reasonable design of the processing and handling systems. The research was conducted to investigate some engineering properties of giant palm seeds in relation to their oil potential. The ripe giant palm fruit was sourced from some parts of Zaria in Kaduna State and Ado Ekiti in Ekiti State, Nigeria. The mesocarps of the fruits collected were removed to obtain the nuts, while the collected nuts were dried under ambient conditions for several days. The actual moisture content of the nuts at the time of the experiment was determined using KT100S Moisture Meter, with moisture content ranged 17.9% to 19.15%. The physical properties determined are axial dimension, geometric mean diameter, arithmetic mean diameter, sphericity, true and bulk densities, porosity, angles of repose, and coefficients of friction. The nuts were measured using a vernier caliper for physical assessment of their sizes. The axial dimensions of 100 nuts were taken and the result shows that the size ranges from 7.30 to 9.32cm for major diameter, 7.2 to 8.9 cm for intermediate diameter, and 4.2 to 6.33 for minor diameter. The mechanical properties determined were compressive force, compressive stress, and deformation both at peak and break using Instron hydraulic universal tensile testing machine. The work also revealed that giant palm seed can be classified as an oil-bearing seed. The seed gave 18% using the solvent extraction method. The results obtained from the study will help in solving the problem of equipment design, handling, and further processing of the seeds.

Keywords: giant palm seeds, engineering properties, oil potential, moisture content, and giant palm fruit

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Authors: E. M. H. Maggie, M. N. A. Nazmey, M. A. Abdel-Sattar, S. A. Saied

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A successful trial of transplanting cotton is reported. Seeds grown in trays for 4-5 weeks in an easily prepared supporting medium such as peat moss or similar plant waste are tried. Careful transplanting of seedlings, with root system as intact as possible, is being made in the permanent field. The practice reduced damping-off incidence rate and allowed full winter crop revenues. Further work is needed to evaluate certain parameters such as growth curve, flowering curve, and yield at economic bases.

Keywords: cotton, transplanting cotton, damping-off diseases, environment sciences

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Authors: Manish Saha, Manish Kumar Niranjan, Saket Asthana

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The K₀.₅Na₀.₅NbO₃ (KNN) system has emerged as one of the most promising lead-free piezoelectric over the years. In this work, we perform a comprehensive investigation of electronic structure, lattice dynamics and dielectric/ferroelectric properties of the room temperature phase of KNN by combining ab-initio DFT-based theoretical analysis and experimental characterization. We assign the symmetry labels to KNN vibrational modes and obtain ab-initio polarized Raman spectra, Infrared (IR) reflectivity, Born-effective charge tensors, oscillator strengths etc. The computed Raman spectrum is found to agree well with the experimental spectrum. In particular, the results suggest that the mode in the range ~840-870 cm-¹ reported in the experimental studies is longitudinal optical (LO) with A_1 symmetry. The Raman mode intensities are calculated for different light polarization set-ups, which suggests the observation of different symmetry modes in different polarization set-ups. The electronic structure of KNN is investigated, and an optical absorption spectrum is obtained. Further, the performances of DFT semi-local, metal-GGA and hybrid exchange-correlations (XC) functionals, in the estimation of KNN band gaps are investigated. The KNN bandgap computed using GGA-1/2 and HSE06 hybrid functional schemes are found to be in excellant agreement with the experimental value. The COHP, electron localization function and Bader charge analysis is also performed to deduce the nature of chemical bonding in the KNN. The solid-state reaction and hydrothermal methods are used to prepare the KNN ceramics, and the effects of grain size on the physical characteristics these ceramics are examined. A comprehensive study on the impact of different synthesis techniques on the structural, electrical, and photocatalytic properties of ferroelectric ceramics KNN. The KNN-S prepared by solid-state method have significantly larger grain size as compared to that for KNN-H prepared by hydrothermal method. Furthermore, the KNN-S is found to exhibit higher dielectric, piezoelectric and ferroelectric properties as compared to KNN-H. On the other hand, the increased photocatalytic activity is observed in KNN-H as compared to KNN-S. As compared to the hydrothermal synthesis, the solid-state synthesis causes an increase in the relative dielectric permittivity (ε^') from 2394 to 3286, remnant polarization (P_r) from 15.38 to 20.41 μC/cm^², planer electromechanical coupling factor (k_p) from 0.19 to 0.28 and piezoelectric coefficient (d_33) from 88 to 125 pC/N. The KNN-S ceramics are also found to have a lower leakage current density, and higher grain resistance than KNN-H ceramic. The enhanced photocatalytic activity of KNN-H is attributed to relatively smaller particle sizes. The KNN-S and KNN-H samples are found to have degradation efficiencies of RhB solution of 20% and 65%, respectively. The experimental study highlights the importance of synthesis methods and how these can be exploited to tailor the dielectric, piezoelectric and photocatalytic properties of KNN. Overall, our study provides several bench-mark important results on KNN that have not been reported so far.

Keywords: lead-free piezoelectric, Raman intensity spectrum, electronic structure, first-principles calculations, solid state synthesis, photocatalysis, hydrothermal synthesis

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Authors: Fuad Abdullah Alatawi

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Microbial infections-based diseases are a significant public health issue around the world, mainly when antibiotic-resistant bacterium types evolve. In this research, we explored the anti-bacterial and anti-cancer potency of iron-oxide (Fe₂O₃) nanoparticles prepared from F. macrocarpa fruit extract. The chemical composition of F. macrocarpa fruit extract was used as a reducing and capping agent for nanoparticles’ synthesis was examined by GC-MS/MS analysis. Then, the prepared nanoparticles were confirmed by various biophysical techniques, including X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), UV-Vis Spectroscopy, and Transmission Electron Microscopy (TEM) and Energy Dispersive Spectroscopy (EDAX), and Dynamic Light Scattering (DLS). Also, the antioxidant capacity of fruit extract was determined through 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), Fluorescence Recovery After Photobleaching (FRAP), Superoxide Dismutase (SOD) assays. Furthermore, the cytotoxicity activities of Fe₂O₃ NPs were determined using the (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) (MTT) test on MCF-7 cells. In the antibacterial assay, lethal doses of the Fe₂O₃NPs effectively inhibited the growth of gram-negative and gram-positive bacteria. The surface damage, ROS production, and protein leakage are the antibacterial mechanisms of Fe₂O₃NPs. Concerning antioxidant activity, the fruit extracts of F. macrocarpa had strong antioxidant properties, which were confirmed by DPPH, ABTS, FRAP, and SOD assays. In addition, the F. microcarpa-derived iron oxide nanomaterials greatly reduced the cell viability of (MCF-7). The GC-MS/MS analysis revealed the presence of 25 main bioactive compounds in the F. microcarpa extract. Overall, the finding of this research revealed that F. microcarpa-derived Fe₂O₃ nanoparticles could be employed as an alternative therapeutic agent to cure microbial infection and breast cancer in humans.

Keywords: ficus microcarpa, iron oxide, antibacterial activity, cytotoxicity

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Authors: Min Chang Shin, Byung Hun Jeong, Jeong Sik Han, Jung Hoon Park

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In modern times, as flight speeds have increased due to improvements in aircraft and missile engine performance, thermal loads have also increased. Because of the friction heat of air flow with high speed on the surface of the vehicle, it is not easy to cool the superheat of the vehicle by the simple air cooling method. For this reason, a cooling method through endothermic heat is attracting attention by using a fuel that causes an endothermic reaction in a high-speed vehicle. There are two main ways of cooling the fuel through the endothermic reaction. The first is physical heat absorption. When the temperature rises, there is a sensible heat that accompanies it. The second is the heat of reaction corresponding to the chemical heat absorption, which absorbs heat during the fuel decomposes. Generally, since the decomposition reaction of the fuel proceeds at a high temperature, it does not achieve a great efficiency in cooling the high-speed flight body. However, when the catalyst is used, decomposition proceeds at a low temperature thereby increasing the cooling efficiency. However, when the catalyst is used as a powder, the catalyst enters the engine and damages the engine or the catalyst can deteriorate the performance due to the sintering. On the other hand, when used in the form of pellets, catalyst loss can be prevented. However, since the specific surface of pellet is small, the efficiency of the catalyst is low. And it can interfere with the flow of fuel, resulting in pressure loss and problems with fuel injection. In this study, we tried to maximize the performance of the catalyst by preparing a hollow fiber type pellet for zeolite ZSM-5, which has a higher amount of heat absorption, than other conventional pellets. The hollow fiber type pellet was prepared by phase inversion method. The hollow fiber type pellet has a finger-like pore and sponge-like pore. So it has a higher specific surface area than conventional pellets. The crystal structure of the prepared ZSM-5 catalyst was confirmed by XRD, and the characteristics of the catalyst were analyzed by TPD/TPR device. This study was conducted as part of the Basic Research Project (Pure-17-20) of Defense Acquisition Program Administration.

Keywords: catalyst, endothermic reaction, high-speed vehicle cooling, zeolite, ZSM-5

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Authors: Petra Hypšová, Martin Seitl

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One of the challenges of forensic psychology is to detect deception during a face-to-face interview. In addition to the classical approaches of monitoring the utterance and its components, detection is also sought by observing behavioral and physiological changes that occur as a result of the increased emotional and cognitive load caused by the production of distorted information. Typical are changes in facial temperature, eye movements and their fixation, pupil dilation, emotional micro-expression, heart rate and its variability. Expanding technological capabilities have opened the space to detect these psychophysiological changes and behavioral manifestations through non-contact technologies that do not interfere with face-to-face interaction. Non-contact deception detection methodology is still in development, and there is a lack of studies that combine multiple non-contact technologies to investigate their accuracy, as well as studies that show how different types of lies produced by different interviewers affect physiological and behavioral changes. The main objective of this study is to apply a specific non-contact technology for deception detection. The next objective is to investigate scenarios in which non-contact deception detection is possible. A series of psychophysiological experiments using infrared thermal imaging, eye tracking and behavioral analysis with FaceReader 9.0 software was used to achieve our goals. In the laboratory experiment, 16 adults (12 women, 4 men) between 18 and 35 years of age (SD = 4.42) were instructed to produce alternating prepared and spontaneous truths and lies. The baseline of each proband was also measured, and its results were compared to the experimental conditions. Because the personality of the examiner (particularly gender and facial appearance) to whom the subject is lying can influence physiological and behavioral changes, the experiment included four different interviewers. The interviewer was represented by a photograph of a face that met the required parameters in terms of gender and facial appearance (i.e., interviewer likability/antipathy) to follow standardized procedures. The subject provided all information to the simulated interviewer. During follow-up analyzes, facial temperature (main ROIs: forehead, cheeks, the tip of the nose, chin, and corners of the eyes), heart rate, emotional expression, intensity and fixation of eye movements and pupil dilation were observed. The results showed that the variables studied varied with respect to the production of prepared truths and lies versus the production of spontaneous truths and lies, as well as the variability of the simulated interviewer. The results also supported the assumption of variability in physiological and behavioural values during the subject's resting state, the so-called baseline, and the production of prepared and spontaneous truths and lies. A series of psychophysiological experiments provided evidence of variability in the areas of interest in the production of truths and lies to different interviewers. The combination of technologies used also led to a comprehensive assessment of the physiological and behavioral changes associated with false and true statements. The study presented here opens the space for further research in the field of lie detection with non-contact technologies.

Keywords: emotional expression decoding, eye-tracking, functional infrared thermal imaging, non-contact deception detection, psychophysiological experiment

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Authors: Yang Gon Seo, Chang-Joon Kim, Dae Hyeok Kim

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It is estimated that 1.5 billion tires are produced worldwide each year which will eventually end up as waste tires representing a major potential waste and environmental problem. Pyrolysis has been great interest in alternative treatment processes for waste tires to produce valuable oil, gas and solid products. The oil and gas products may be used directly as a fuel or a chemical feedstock. The solid produced from the pyrolysis of tires ranges typically from 30 to 45 wt% and have high carbon contents of up to 90 wt%. However, most notably the solid have high sulfur contents from 2 to 3 wt% and ash contents from 8 to 15 wt% related to the additive metals. Upgrading tire pyrolysis products to high-value products has concentrated on solid upgrading to higher quality carbon black and to activated carbon. Hydrogen sulfide and ammonia are one of the common malodorous compounds that can be found in emissions from many sewages treatment plants and industrial plants. Therefore, removing these harmful gasses from emissions is of significance in both life and industry because they can cause health problems to human and detrimental effects on the catalysts. In this work, pyrolytic carbon black from waste tires was used to develop adsorbent with good adsorption capacity for removal of hydrogen and ammonia. Pyrolytic carbon blacks were prepared by pyrolysis of waste tire chips ranged from 5 to 20 mm under the nitrogen atmosphere at 600℃ for 1 hour. Pellet-type adsorbents were prepared by a mixture of carbon black, metal oxide and sodium hydroxide or hydrochloric acid, and their adsorption capacities were estimated by using the breakthrough curve of a continuous fixed bed adsorption column at ambient condition. The adsorbent was manufactured with a mixture of carbon black, iron oxide(III), and sodium hydroxide showed the maximum working capacity of hydrogen sulfide. For ammonia, maximum working capacity was obtained by the adsorbent manufactured with a mixture of carbon black, copper oxide(II), and hydrochloric acid.

Keywords: adsorbent, ammonia, pyrolytic carbon black, hydrogen sulfide, metal oxide

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Authors: Anteneh Wodaje Bayeh, Daniel Manaye Kabtamu, Chen-Hao Wang

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As one of the most promising electrochemical energy storage systems, vanadium redox flow batteries (VRFBs) have received increasing attention owing to their attractive features for largescale storage applications. However, their high production cost and relatively low energy efficiency still limit their feasibility. For practical implementation, it is of great interest to improve their efficiency and reduce their cost. One of the key components of VRFBs that can greatly influence the efficiency and final cost is the electrode, which provide the reactions sites for redox couples (VO²⁺/VO₂ + and V²⁺/V³⁺). Carbon-based materials are considered to be the most feasible electrode materials in the VRFB because of their excellent potential in terms of operation range, good permeability, large surface area, and reasonable cost. However, owing to limited electrochemical activity and reversibility and poor wettability due to its hydrophobic properties, the performance of the cell employing carbon-based electrodes remained limited. To address the challenges, we synthesized heteroatom-doped bimetallic oxide grown on the surface of carbon through the one-step approach. When applied to VRFBs, the prepared electrode exhibits significant electrocatalytic effect toward the VO²⁺/VO₂ + and V³⁺/V²⁺ redox reaction compared with that of pristine carbon. It is found that the presence of heteroatom on metal oxide promotes the absorption of vanadium ions. The controlled morphology of bimetallic metal oxide also exposes more active sites for the redox reaction of vanadium ions. Hence, the prepared electrode displays the best electrochemical performance with energy and voltage efficiencies of 74.8% and 78.9%, respectively, which is much higher than those of 59.8% and 63.2% obtained from the pristine carbon at high current density. Moreover, the electrode exhibit durability and stability in an acidic electrolyte during long-term operation for 1000 cycles at the higher current density.

Keywords: VRFB, VO²⁺/VO₂ + and V³⁺/V²⁺ redox couples, graphite felt, heteroatom-doping

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Authors: Derek O Reilly, Piotr Milczarski, Shane Dowdall, Artur Hłobaż, Krzysztof Podlaski, Hiram Bollaert

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Learning through creation of contextual games is a very promising way/tool for interdisciplinary and international group projects. During 2013 and 2014 we took part and organized two intensive students projects in different conditions. The projects enrolled 68 students and 12 mentors from 5 countries. In the paper we want to share our experience how to strengthen the chances to succeed in short (12-15 days long) student projects. In our case almost all teams prepared working prototype and the results were highly appreciated by external experts.

Keywords: contextual games, mobile games, GGULIVRR, walkabout, Erasmus intensive programme

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Authors: Sadaf Saeed

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The consideration of walkability as an urban design parameter in conjunction with transit-oriented development is an established trend in the developed countries but an upcoming trend in developing countries. In Pakistan, the first Bus Rapid Transit (locally called as Metro Bus) has been introduced in the city of Lahore in 2013 where around 40 percent of the riders access to transit stations by walking. To what extent the aspect of walkability has been considered in the local scenario? To address this question, this paper presents an account of urban design parameters regarding pedestrian provisions and quality of walking environment between Metro Bus stations and users’ destination in the transit neighbourhoods (areas up to 500-meter radius). The primary and secondary data for objective and subjective walkability measurements has been used for neighbourhoods of five selected transit stations ranked against the predefined critical assessed factors (CAF). The multi-criteria approach including visual and geospatially-based parameters at street level, along with walkability index score at selected sites linked with CAF evaluation were the selected methods for this study. The acceptability of walkability as an urban design parameter for transit planning in terms of connectivity and social implications of the concept has also been analysed in the local context. The paper highlights that the aspect of walkability in Lahore is being derelict owing to the focus of government on other initiatives such as park and ride and feeder bus services for mobility of passengers. However, the pedestrian-friendly design parameters as a part of future transit planning can enhance social, liveable and interactive walking environment within transit neighbourhoods.

Keywords: walkability, sustainability, transit neighborhoods, social communities

Procedia PDF Downloads 241

Authors: Zhuomin Zou, Thijs Van Landeghem, Elke Gruyaert

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Using supplementary cementitious materials, such as blast-furnace slag and limestone, to replace cement clinker is a promising method to reduce the carbon emissions from cement production. To efficiently use slag and limestone, it is necessary to carefully select the particle size distribution (PSD) of the binders. This study investigated the effects of the PSD of binders on the performance of slag-limestone ternary cement. The Portland cement (PC) was prepared by grinding 95% clinker + 5% gypsum. Based on the PSD parameters of the binders, three types of ternary cements with a similar overall PSD were designed, i.e., NO.1 fine slag, medium PC, and coarse limestone; NO.2 fine limestone, medium PC, and coarse slag; NO.3. fine PC, medium slag, and coarse limestone. The binder contents in the ternary cements were (a) 50 % PC, 40 % slag, and 10 % limestone (called high cement group) or (b) 35 % PC, 55 % slag, and 10 % limestone (called low cement group). The pure PC and binary cement with 50% slag and 50% PC prepared with the same binders as the ternary cement were considered as reference cements. All these cements were used to investigate the mortar performance in terms of workability, strength at 2, 7, 28, and 90 days, carbonation resistance, and non-steady state chloride migration resistance at 28 and 56 days. Results show that blending medium PC with fine slag could exhibit comparable performance to blending fine PC with medium/coarse slag in binary cement. For the three ternary cements in the high cement group, ternary cement with fine limestone (NO.2) shows the lowest strength, carbonation, and chloride migration performance. Ternary cements with fine slag (NO.1) and with fine PC (NO.3) show the highest flexural strength at early and late ages, respectively. In addition, compared with ternary cement with fine PC (NO.3), ternary cement with fine slag (NO.1) has a similar carbonation resistance and a better chloride migration resistance. For the low cement group, three ternary cements have a similar flexural and compressive strength before 7 days. After 28 days, ternary cement with fine limestone (NO.2) shows the highest flexural strength while fine PC (NO.3) has the highest compressive strength. In addition, ternary cement with fine slag (NO.1) shows a better chloride migration resistance but a lower carbonation resistance compared with the other two ternary cements. Moreover, the durability performance of ternary cement with fine PC (NO.3) is better than that of fine limestone (NO.2).

Keywords: limestone, particle size distribution, slag, ternary cement

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Authors: Elizabeth Farquhar, Erich Ritter

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Studying shark's interaction with humans and their behavioral responses will have enormous implications for other fields of marine biology and oceanography. The health of sharks has direct impacts on the stability of human society with a reported 3.5 billion people depending on the ocean for food and/or livelihood. Discovering how sharks behave and interact with people, will have enormous implications for future studies, along with the development of more effective ways to reduce negative shark/human interactions. This specific study investigates the effects of contrasting ponchos worn by divers on the approach distances of Carcharhinus perezi. Data was collected over a two week period at a test site off the shore of Eleuthera Island in the Bahamas, with a depth of approximately 55 feet during mid-August. Sixty-minute dive trials were conducted and videoed from above with 5-meter radius markers on the ocean floor surrounding the two divers, kneeling back-to-back. Five poncho colors were worn by the two divers (black, navy blue, dark green, yellow and orange), rotating the color permutations randomly to test the distance a shark will approach each color. Results indicate significantly closer approach patterns when divers were wearing orange ponchos, and the combination of orange with black and blue ponchos were found to be statistically significant. These results are relevant to understanding how sharks perceive contrast and dive equipment in the marine environment, which could have the potential to prevent negative shark/human interactions.

Keywords: shark behavior, animal behavior, marine biology, conservation

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Authors: Gülcan Taşkıran, Ülkü Tatar Baykal

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Aim: To identify nurses’ perceived competencies for disaster preparedness. Background: Recently, the number of disasters has increased worldwide. Since disasters often strike without warning, healthcare providers, especially nurses must be prepared with appropriate competencies for disaster procedures. Nurses’ perceptions of their own competencies for disaster preparedness need to be evaluated to aid in the creation of effective national plans and educational programs. Design: This study was conducted with a descriptive and cross-sectional design. Methods: Nurses’ perceptions were assessed using the 13-item Demographic Profile Questionnaire that is based on previous literature and the 45-item Nurses’ Perception of Core Competencies for Disaster Preparedness Scale (NPCDPS). Data were collected from June to September 2014 from 406 (79.9% return rate) Turkish nurses working in the western region of Turkey. Results: At the end of the study, it was found that out of the nurses whose mean age was 31.27 ± 5.86 and mean of working time was 8.07 ± 6.60 by the time vast majority of the nurses were women (85.7%), married (59.4%), bachelor’s degree holder (88.2%) and service nurses (56.2%). The most potential disaster that nurses think is an earthquake (70.9%) by the time majority of nurses consider having a role as a nurse at every stage of disasters. The mean total point score of nurses’ perception of disaster preparedness was 4.62. The mean total point score of the nurses from the Nurses’ Perception of Core Competencies for Disaster Preparedness Scale was 133.96. When the subscales’ mean scores are examined, the highest average of the mean score is for Technical Skills (44.52), and the lowest is for Critical Thinking Skills (10.47). When the subscales of Nurses’ Perception of Core Competencies for Disaster Preparedness Scale compared with sex, marital status and education level out of independent variable of nurses there is no significant difference (p > 0.05); compared with age group, working years, duty and being with a disaster out of independent variable of nurses there is a significant difference (p ≤ 0.05). Conclusion: Nurses generally perceive themselves as sufficient at a ‘medium level’ in terms of meeting the core competencies that are required for disaster preparedness. Nurses are not adequately prepared for disasters, but they are aware of the need for such preparation and disaster education. Disaster management training should be given to all nurses in their basic education.

Keywords: disaster competencies, disaster management, disaster nursing, disaster preparedness, nursing, nursing administration, Turkish nurses

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Authors: Wiqar Hussain Shah

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The Structural, magnetic and transport behavior of La1-xCaxMnO3+ (x=0.48, 0.50, 0.52 and 0.55 and =0.015) compositions close to charge ordering, was studied through XRD, resistivity, DC magnetization and AC susceptibility measurements. With time and thermal cycling (T<300 K) there is an irreversible transformation of the low-temperature phase from a partially ferromagnetic and metallic to one that is less ferromagnetic and highly resistive. For instance, an increase of resistivity can be observed by thermal cycling, where no effect is obtained for lower Ca concentration. The time changes in the magnetization are logarithmic in general and activation energies are consistent with those expected for electron transfer between Mn ions. The data suggest that oxygen non-stoichiometry results in mechanical strains in this two-phase system, leading to the development of irreversible metastable states, which relax towards the more stable charge-ordered and antiferromagnetic microdomains at the nano-meter size. This behavior is interpreted in terms of strains induced charge localization at the interface between FM/AFM domains in the antiferromagnetic matrix. Charge, orbital ordering and phase separation play a prominent role in the appearance of such properties, since they can be modified in a spectacular manner by external factor, making the different physical properties metastable. Here we describe two factors that deeply modify those properties, viz. the doping concentration and the thermal cycling. The metastable state is recovered by the high temperature annealing. We also measure the magnetic relaxation in the metastable state and also the revival of the metastable state (in a relaxed sample) due to high temperature (800 ) thermal treatment.

Keywords: Rare-earth maganites, nano-structural materials, doping effects on electrical, magnetic properties, competing interactions

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Authors: Simone F. Medeiros, Jessica M. Fonseca, Gizelda M. Alves, Danilo M. Santos, Sérgio P. Campana-Filho, Amilton M. Santos

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Stimuli responsive and biocompatible hydrogel nanoparticles have gained special attention as systems for potential applications in controlled release of drugs to improve their therapeutic efficacy while minimizing side effects. In this work, novel solid dispersions based on thermo- and pH-responsive poly(N-vinylcaprolactam-co-itaconic acid-co-ethylene- glycol dimethacrylate) hydrogel nanoparticles embedded in chitosan matrices were prepared via spray drying for controlled release of ketoprofen. Firstly, the hydrogel nanoparticles containing ketoprofen were prepared via precipitation polymerization and their stimuli-responsive behavior, thermal properties, chemical composition, encapsulation efficiency and morphology were characterized. Then, hydrogel nanoparticles with different particles size were embedded into chitosan matrices via spray-drying. Scanning electron microscopy (SEM) analyses were performed to investigate the particles size, dispersity and morphology. Finally, ketoprofen release profiles were studied as a function of pH and temperature. Chitosan/poly(NVCL-co-IA-co-EGDMA)-ketoprofen microparticles presented spherical shape, rough surface and pronounced agglomeration, indicating that hydrogels nanoparticles loaded with ketoprofen modified the surface of chitosan matrix. The maximum encapsulation efficiency of ketoprofen into hydrogel nanoparticles was 57.8% and the electrostatic interactions between amino groups from chitosan and carboxylic groups from hydrogel nanoparticles were able to control ketoprofen release. The hydrogel nanoparticles themselves were capable to retard the release of ketoprofen-loaded until 48h of in vitro release tests, while their incorporation into chitosan matrix achieved a maximum percentage of drug release of 45%, using a mass ratio of chitosan: poly(NVCL-co-IA-co-EGDMA equal to 10:7, and 69%, using a mass ratio of chitosan: poly(NVCL-co-IA-co-EGDMA equal to 5:2.

Keywords: hydrogel nanoparticles, poly(N-vinylcaprolactam-co-itaconic acid-co-ethylene- glycol dimethacrylate), chitosan, ketoprofen, spray-drying

Procedia PDF Downloads 258

Authors: Elham A. Kwildi, Yahia S. Abugnah, Nuri S. Madi

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This study was designed to evaluate the microbiological quality and safety of two types of salads prepared at a catering center affiliated with Libyan Airlines in Tripoli, Libya. Two hundred and twenty-one (221) samples (132 economy-class and 89 first- class) were used in this project which lasted for ten months. Biweekly, microbiological tests were performed which included total plate count (TPC) and total coliforms (TCF), in addition to enumeration and/or detection of some pathogenic bacteria mainly Escherichia coli, Staphylococcus aureus, Bacillus cereus, Salmonella sp, Listeria sp and Vibrio parahaemolyticus parahaemolyticus, By using conventional as well as compact dry methods. Results indicated that TPC of type 1 salad ranged between (<10 – 62 x 103 cfu/gm) and (<10 to 36 x103 cfu/g), while TCF were (<10 – 41 x 103 cfu/gm) and (< 10 to 66 x102 cfu/g) using both methods of detection respectively. On the other hand, TPC of type 2 salad were: (1 × 10 – 52 x 103) and (<10 – 55 x 103 cfu/gm) and in the range of (1 x10 to 45x103 cfu/g), and the (TCF) counts were between (< 10 to 55x103 cfu/g) and (< 10 to 34 x103 cfu/g) using the 1st and the 2nd methods of detection respectively. Also, the pathogens mentioned above were detected in both types of salads, but their levels varied according to the type of salad and the method of detection. The level of Staphylococcus aureus, for instance, was 17.4% using conventional method versus 14.4% using the compact dry method. Similarly, E. coli was 7.6% and 9.8%, while Salmonella sp. recorded the least percentage i.e. 3% and 3.8% with the two mentioned methods respectively. First class salads were also found to contain the same pathogens, but the level of E. coli was relatively higher in this case (14.6% and 16.9%) using conventional and compact dry methods respectively. The second rank came Staphylococcus aureus (13.5%) and (11.2%), followed by Salmonella (6.74%) and 6.70%). The least percentage was for Vibrio parahaemolyticus (4.9%) which was detected in the first class salads only. The other two pathogens Bacillus cereus and Listeria sp. were not detected in either one of the salads. Finally, it is worth mentioning that there was a significant decline in TPC and TCF counts in addition to the disappearance of pathogenic bacteria after the 6-7th month of the study which coincided with the first trial of the HACCP system at the center. The ups and downs in the counts along the early stages of the study reveal that there is a need for some important correction measures including more emphasis on training of the personnel in applying the HACCP system effectively.

Keywords: air travel, vegetable salads, foodborne outbreaks, Libya

Procedia PDF Downloads 322

Authors: H. Ferfera-Harrar, T. Benhalima, D. Lerari

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Contamination of water, due to the discharge of untreated industrial wastewaters into the ecosystem, has become a serious problem for many countries. In this study, bioadsorbents based on chitosan-g-poly(acrylamide) and montmorillonite (MMt) clay (CTS-g-PAAm/MMt) hydrogel nanocomposites were prepared via free‐radical grafting copolymerization and crosslinking of acrylamide monomer (AAm) onto natural polysaccharide chitosan (CTS) as backbone, in presence of various contents of MMt clay as nanofiller. Then, they were hydrolyzed to obtain highly functionalized pH‐sensitive nanomaterials with uppermost swelling properties. Their structure characterization was conducted by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses. The adsorption performances of the developed nanohybrids were examined for removal of methylene blue (MB) cationic dye from aqueous solutions. The factors affecting the removal of MB, such as clay content, pH medium, adsorbent dose, initial dye concentration and temperature were explored. The adsorption process was found to be highly pH dependent. From adsorption kinetic results, the prepared adsorbents showed remarkable adsorption capacity and fast adsorption rate, mainly more than 88% of MB removal efficiency was reached after 50 min in 200 mg L^-1 of dye solution. In addition, the incorporating of various content of clay has enhanced adsorption capacity of CTS-g-PAAm matrix from 1685 to a highest value of 1749 mg g^-1 for the optimized nanocomposite containing 2 wt.% of MMt. The experimental kinetic data were well described by the pseudo-second-order model, while the equilibrium data were represented perfectly by Langmuir isotherm model. The maximum Langmuir equilibrium adsorption capacity (q_m) was found to increase from 2173 mg g⁻¹ until 2221 mg g⁻¹ by adding 2 wt.% of clay nanofiller. Thermodynamic parameters revealed the spontaneous and endothermic nature of the process. In addition, the reusability study revealed that these bioadsorbents could be well regenerated with desorption efficiency overhead 87% and without any obvious decrease of removal efficiency as compared to starting ones even after four consecutive adsorption/desorption cycles, which exceeded 64%. These results suggest that the optimized nanocomposites are promising as low cost bioadsorbents.

Keywords: chitosan, clay, dye adsorption, hydrogels nanocomposites

Procedia PDF Downloads 119

Authors: Johnson O. Adeogo, Ayodele S. Oluwole, O. Akinsanmi, Olawale J. Olaluyi

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In this 5G network, very high traffic density in densely populated areas, most especially in densely populated areas, is one of the key requirements. Radiation reduction becomes one of the major concerns to secure the future life of mobile network users in ultra-dense network areas using an improved coordinated multipoint technology. Coordinated Multi-Point (CoMP) is based on transmission and/or reception at multiple separated points with improved coordination among them to actively manage the interference for the users. Small cells have two major objectives: one, they provide good coverage and/or performance. Network users can maintain a good quality signal network by directly connecting to the cell. Two is using CoMP, which involves the use of multiple base stations (MBS) to cooperate by transmitting and/or receiving at the same time in order to reduce the possibility of electromagnetic radiation increase. Therefore, the influence of the screen guard with rubber condom on the mobile transceivers as one major piece of equipment radiating electromagnetic radiation was investigated by mobile network users amidst ultra-dense networks in 5g. The results were compared with the same mobile transceivers without screen guards and rubber condoms under the same network conditions. The 5 cm distance from the mobile transceivers was measured with the help of a ruler, and the intensity of Radio Frequency (RF) radiation was measured using an RF meter. The results show that the intensity of radiation from various mobile transceivers without screen guides and condoms was higher than the mobile transceivers with screen guides and condoms when call conversation was on at both ends.

Keywords: ultra-dense networks, mobile network users, 5g, coordinated multi-point.

Procedia PDF Downloads 94

Authors: Haruna Karamba, Nafisa Muhammad Danyaro

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The study describe the action of natural latex (extract) of two sub-aquatic macrophytes plants i.e., Cassia occidentalis and Physalis angulata which were tested against two water snail species; Bulinus globusus and Lymnaea natalensis, the intermediate host of Bilharziasis (chistosomiasis) in the tropical countries. Bilherziasis is a disease prevalent and endermic to tropical Africa, seriously undermining health status of Nigerian youth. The easiest way to eradicate the disease is to eliminate the secondary host of the pathogen, chistosoma species. Therefore we carried out a research to investigate the molluscicidal effect of the leaf extract of C. occidentalis and P. angulata on mortality rate of B. globusus and L. natalensis water snails using pond water in the laboratory of science laboratory department of Kano State Polytechnic, Nigeria. One hundred and fifty juveniles’ snails were collected from Jakara Dam in the Northeastern part of Kano, Nigeria. The snails were put inside a plastic container and transported immediately to the laboratory where they were transferred into reservoir tank containing pond water and kept for 48 hours to get acclimatized with laboratory environment. Twelve water bathes 2/3 filled with pond water were prepared and kept in the laboratory. Leaf extract of the plants were obtained by blending and homogenizing the leaf tissue from which the extract were obtained and prepared in 10, 20, 30, 40 and 50 ppm, in addition to 0 ppm, which served as control. Ten snails were placed in each of the twelve water bathes. Six water bathes for the species of C. accidentalis extract and other six for P. angulata. The treatment combinations were maintained for 2 days after which the number of living snails present in each water bathes were counted and subsequently at 2 days intervals. The result indicated that extracts from both plants were lethal to the snails as concentration of the extract increases particularly mortality rate was highest at 40 and 50 ppm. Conclusively the toxicity of the extracts from these plants proven lethal to snails and hence can be used as molluscicides for cheap and easy method of eliminating water snails and therefore reducing the incidence of Bilharziasis.

Keywords: schistosomiasis, bilharziasis, Bulinus globusus, Lymnea natalensis, Physalis angulata, Cassia occidentalis, Kano

Procedia PDF Downloads 355

Authors: Jinlu Ruan, Liang Chen, Bo Liu, Xiaoping Ouyang, Zhichao Zhu, Zhongbing Zhang, Shiyi He, Mengxuan Xu

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Plastic scintillators play an important role in the measurement of a mixed neutron/gamma pulsed radiation, neutron radiography and pulse shape discrimination technology. In some research, these luminescent properties are necessary that photons produced by the interactions between a plastic scintillator and radiations can be detected as much as possible by the photoelectric detectors and more photons can be emitted from the scintillators along a specific direction where detectors are located. Unfortunately, a majority of these photons produced are trapped in the plastic scintillators due to the total internal reflection (TIR), because there is a significant light-trapping effect when the incident angle of internal scintillation light is larger than the critical angle. Some of these photons trapped in the scintillator may be absorbed by the scintillator itself and the others are emitted from the edges of the scintillator. This makes the light extraction of plastic scintillators very low. Moreover, only a small portion of the photons emitted from the scintillator easily can be detected by detectors effectively, because the distribution of the emission directions of this portion of photons exhibits approximate Lambertian angular profile following a cosine emission law. Therefore, enhancing the light extraction efficiency and adjusting the emission angular profile become the keys for improving the number of photons detected by the detectors. In recent years, photonic crystal structures have been covered on inorganic scintillators to enhance the light extraction efficiency and adjust the angular profile of scintillation light successfully. However, that, preparation methods of photonic crystals will deteriorate performance of plastic scintillators and even destroy the plastic scintillators, makes the investigation on preparation methods of photonic crystals for plastic scintillators and luminescent properties of plastic scintillators with photonic crystal structures inadequate. Although we have successfully made photonic crystal structures covered on the surface of plastic scintillators by a modified self-assembly technique and achieved a great enhance of light extraction efficiency without evident angular-dependence for the angular profile of scintillation light, the preparation of photonic crystal structures with large area (the diameter is larger than 6cm) and perfect periodic structure is still difficult. In this paper, large area photonic crystals on the surface of scintillators were prepared by nanoimprint lithography firstly, and then a conformal layer with material of high refractive index on the surface of photonic crystal by atomic layer deposition technique in order to enhance the stability of photonic crystal structures and increase the number of leaky modes for improving the light extraction efficiency. The luminescent properties of the plastic scintillator with photonic crystals prepared by the mentioned method are compared with those of the plastic scintillator without photonic crystal. The results indicate that the number of photons detected by detectors is increased by the enhanced light extraction efficiency and the angular profile of scintillation light exhibits evident angular-dependence for the scintillator with photonic crystals. The mentioned preparation of photonic crystals is beneficial to scintillation detection applications and lays an important technique foundation for the plastic scintillators to meet special requirements under different application backgrounds.

Keywords: angular profile, atomic layer deposition, light extraction efficiency, plastic scintillator, photonic crystal

Procedia PDF Downloads 197

Authors: Navpreet Kaur, Himkusha Thakur, Nirmal Prabhakar

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The most controversial issue in crop production is the use of Organophosphate insecticides. This is evident in many reports that Organophosphate (OP) insecticides, among the broad range of pesticides are mainly involved in acute and chronic poisoning cases. OPs detection is of crucial importance for health protection, food and environmental safety. In our study, a nanocomposite of poly (3,4 ethylenedioxythiophene) (PEDOT) and multi-walled carbon nanotubes (MWCNTs) has been deposited electrochemically onto the surface of fluorine doped tin oxide sheets (FTO) for the analysis of malathion OP. The -COOH functionalization of MWCNTs has been done for the covalent binding with amino groups of AChE enzyme. The use of PEDOT-MWCNT films exhibited an excellent conductivity, enables fast transfer kinetics and provided a favourable biocompatible microenvironment for AChE, for the significant malathion OP detection. The prepared biosensors were characterized by Fourier transform infrared spectrometry (FTIR), Field emission-scanning electron microscopy (FE-SEM) and electrochemical studies. Various optimization studies were done for different parameters including pH (7.5), AChE concentration (50 mU), substrate concentration (0.3 mM) and inhibition time (10 min). Substrate kinetics has been performed and studied for the determination of Michaelis Menten constant. The detection limit for malathion OP was calculated to be 1 fM within the linear range 1 fM to 1 µM. The activity of inhibited AChE enzyme was restored to 98% of its original value by 2-pyridine aldoxime methiodide (2-PAM) (5 mM) treatment for 11 min. The oxime 2-PAM is able to remove malathion from the active site of AChE by means of trans-esterification reaction. The storage stability and reusability of the prepared biosensor is observed to be 30 days and seven times, respectively. The application of the developed biosensor has also been evaluated for spiked lettuce sample. Recoveries of malathion from the spiked lettuce sample ranged between 96-98%. The low detection limit obtained by the developed biosensor made them reliable, sensitive and a low cost process.

Keywords: PEDOT-MWCNT, malathion, organophosphates, acetylcholinesterase, biosensor, oxime (2-PAM)

Procedia PDF Downloads 442

Authors: Gulcin Yildiz

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Drying (dehydration) is the process of removing water from food in order to preserve the food and an alternative to reduce post-harvest loss of fruits. Different pre-treatment methods have been developed for fruit drying, such as ultrasound. If no pre-treatment is done, the fruits will continue to darken after they are dried. However, the effects of ultrasound as pre-treatment on drying of apples has not been well documented. This study was undertaken to investigate the effect of ultrasound as pre-treatment before oven drying of red delicious and golden delicious apples. Red delicious and golden delicious apples were dried in different temperatures. Before performing drying experiments in an oven at 50, 75 and 100 °C, ultrasound as pretreatment was applied in 5, 10, and 15 minutes. Colors of the dried apples were measured with a Minolta Chroma Meter CR-300 (Minolta Camera Co. Ltd., Osaka, Japan) by directly holding the device vertically to the surface of the samples. Content of total phenols was determined spectrophotometrically with the FolinCiocalteau assay, and the antioxidant capacity was evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The samples (both red delicious and golden delicious apples) with longer ultrasound treatment produced higher weight loss due to the changes in tissue structure. However less phenolic content and antioxidant capacity were observed for the samples with longer ultrasound pre-treatment. The highest total phenolic content (TPC) was determined in dried apples at 75 °C with 5 minutes pre-treatment ultrasound and the lowest TPC was determined in dried apples at 50 °C with 15 minutes pre-treatment ultrasound which was subjected to the longest ultrasound pre-treatment and drying. The combination of 5 min of ultrasound pre-treatment and 75 °C of oven-drying showed to be the best combination for an energy efficient process. This combination exhibited good antioxidant properties as well. The present study clearly demonstrated that applying ultrasound as pre-treatment for drying of apples is an effective process in terms of quality of dried products, time, and energy.

Keywords: golden delicious apples, red delicious apples, total phenolic content, Ultrasound

Procedia PDF Downloads 292

Authors: T. Ul Rehman, S. Agnello, F. M. Gelardi, M. M. Calvino, G. Lazzara, G. Buscarino, M. Cannas

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Metal-Organic Frameworks (MOFs) have emerged as promising candidates for detecting metal ions owing to their large surface area, customizable porosity, and diverse functionalities. In recent years, there has been a surge in research focused on MOFs with luminescent properties. These frameworks are constructed through coordinated bonding between metal ions and multi-dentate ligands, resulting in inherent fluorescent structures. Their luminescent behavior is influenced by factors like structural composition, surface morphology, pore volume, and interactions with target analytes, particularly metal ions. MOFs exhibit various sensing mechanisms, including photo-induced electron transfer (PET) and charge transfer processes such as ligand-to-metal (LMCT) and metal-to-ligand (MLCT) transitions. Among these, MIL-53(Al) stands out due to its flexibility, stability, and specific affinity towards certain metal ions, making it a promising platform for selective metal ion sensing. This study investigates the structural, thermal, and luminescent properties of MIL-53(Al) metal-organic framework (MOF) upon Fe3+ cation exchange. Two separate sets of samples were prepared to activate the MOF powder at different temperatures. The first set of samples, referred to as MIL-53(Al), activated (120°C), was prepared by activating the raw powder in a glass tube at 120°C for 12 hours and then sealing it. The second set of samples, referred to as MIL-53(Al), activated (300°C), was prepared by activating the MIL-53(Al) powder in a glass tube at 300°C for 70 hours. Additionally, 25 mg of MIL-53(Al) powder was dispersed in 5 mL of Fe3+ solution at various concentrations (0.1-100 mM) for the cation exchange experiment. The suspension was centrifuged for five minutes at 10,000 rpm to extract MIL-53(Al) powder. After three rounds of washing with ultrapure water, MIL-53(Al) powder was heated at 120°C for 12 hours. For PXRD and TGA analyses, a sample of the obtained MIL-53(Al) was used. We also activated the cation-exchanged samples for time-resolved photoluminescence (TRPL) measurements at two distinct temperatures (120 and 300°C) for comparative analysis. Powder X-ray diffraction patterns reveal amorphization in samples with higher Fe3+ concentrations, attributed to alterations in coordination environments and ion exchange dynamics. Thermal decomposition analysis shows reduced weight loss in Fe3+-exchanged MOFs, indicating enhanced stability due to stronger metal-ligand bonds and altered decomposition pathways. Raman spectroscopy demonstrates intensity decrease, shape disruption, and frequency shifts, indicative of structural perturbations induced by cation exchange. Photoluminescence spectra exhibit ligand-based emission (π-π* or n-π*) and ligand-to-metal charge transfer (LMCT), influenced by activation temperature and Fe3+ incorporation. Quenching of luminescence intensity and shorter lifetimes upon Fe3+ exchange result from structural distortions and Fe3+ binding to organic linkers. In a nutshell, this research underscores the complex interplay between composition, structure, and properties in MOFs, offering insights into their potential for diverse applications in catalysis, gas storage, and luminescent devices.

Keywords: Fe³⁺ cation exchange, luminescent metal-organic frameworks (LMOFs), MIL-53(Al), solid-state analysis

Procedia PDF Downloads 61

Authors: Adedolapo Taiwo Adeyemi, Success Ayodeji Fasanmi

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The emergence of the coronavirus pandemic and the rate of the spread affected a lot of activities across the world. This led to the introduction of online learning modes in several countries after institutions were shut down. Unfortunately, most public universities in Nigeria could not switch to the online mode because they were not prepared for it, as they do not have the technological capacity to support a full online learning mode. This study examines the readiness of university and the attitude of undergraduates towards online learning mode in Obafemi Awolowo University (OAU), Ile Ife. It investigated the skills and competencies of students for online learning as well as the university’s readiness towards online learning mode; the effort was made to identify challenges of online teaching and learning in the study area, and suggested solutions were advanced. OAU was selected because it is adjudged to be the leading Information and Communication Technology (ICT) driven institution in Nigeria. The descriptive survey research design was used for the study. A total of 256 academic staff and 1503 undergraduates were selected across six faculties out of the thirteen faculties in the University. Two set of questionnaires were used to get responses from the selected respondents. The result showed that students have the skills and competence to operate e-learning facilities but are faced with challenges such as high data cost, erratic power supply, and lack of gadgets, among others. The study found out that the university was not prepared for online learning mode as it lacks basic technological facilities to support it. The study equally showed that while lecturers possess certain skills in using some e-learning applications, they were limited by the unavailability of online support gadgets, poor internet connectivity, and unstable power supply. Furthermore, the assessment of student attitude towards online learning mode shows that the students found the online learning mode very challenging as they had to bear the huge cost of data. Lecturers also faced the same challenge as they had to pay a lot to buy data, and the networks were sometimes unstable. The study recommended that adequate funding needs to be provided to public universities by the government while the management of institutions must build technological capacities to support online learning mode in the hybrid form and on a full basis in case of future emergencies.

Keywords: universities, online learning, undergraduates, attitude

Procedia PDF Downloads 92

Authors: Pavel Baroch, Jiri Rezek, Michal Prochazka, Tomas Kozak, Jiri Houska

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Transparent semiconducting amorphous IGZO films have attracted great attention due to their excellent electrical properties and possible utilization in thin film transistors or in photovoltaic applications as they show 20-50 times higher mobility than that of amorphous silicon. It is also known that the properties of IGZO films are highly sensitive to process parameters, especially to oxygen partial pressure. In this study we have focused on the comparison of properties of transparent semiconducting amorphous indium gallium zinc oxide (IGZO) thin films prepared by conventional sputtering methods and those prepared by high power impulse magnetron sputtering (HiPIMS) method. Furthermore we tried to optimize electrical and optical properties of the IGZO thin films and to investigate possibility to apply these coatings on thermally sensitive flexible substrates. We employed dc, pulsed dc, mid frequency sine wave and HiPIMS power supplies for magnetron deposition. Magnetrons were equipped with sintered ceramic InGaZnO targets. As oxygen vacancies are considered to be the main source of the carriers in IGZO films, it is expected that with the increase of oxygen partial pressure number of oxygen vacancies decreases which results in the increase of film resistivity. Therefore in all experiments we focused on the effect of oxygen partial pressure, discharge power and pulsed power mode on the electrical, optical and mechanical properties of IGZO thin films and also on the thermal load deposited to the substrate. As expected, we have observed a very fast transition between low- and high-resistivity films depending on oxygen partial pressure when deposition using conventional sputtering methods/power supplies have been utilized. Therefore we established and utilized HiPIMS sputtering system for enlargement of operation window for better control of IGZO thin film properties. It is shown that with this system we are able to effectively eliminate steep transition between low and high resistivity films exhibited by DC mode of sputtering and the electrical resistivity can be effectively controlled in the wide resistivity range of 10-² to 10⁵ Ω.cm. The highest mobility of charge carriers (up to 50 cm2/V.s) was obtained at very low oxygen partial pressures. Utilization of HiPIMS also led to significant decrease in thermal load deposited to the substrate which is beneficial for deposition on the thermally sensitive and flexible polymer substrates. Deposition rate as a function of discharge power and oxygen partial pressure was also systematically investigated and the results from optical, electrical and structure analysis will be discussed in detail. Most important result which we have obtained demonstrates almost linear control of IGZO thin films resistivity with increasing of oxygen partial pressure utilizing HiPIMS mode of sputtering and highly transparent films with low resistivity were prepared already at low pO2. It was also found that utilization of HiPIMS technique resulted in significant improvement of surface smoothness in reactive mode of sputtering (with increasing of oxygen partial pressure).

Keywords: charge carrier mobility, HiPIMS, IGZO, resistivity

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Authors: Mohammed Nasir Kajama, Ngozi Claribelle Nwogu, Edward Gobina

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Pt/γ-Al2O3 membrane catalysts were prepared via an evaporative-crystallization deposition method. The obtained Pt/γ-Al2O3 catalyst activity was tested after characterization (SEM-EDAX observation, BET measurement, permeability assessment) in the catalytic oxidation of selected volatile organic compound (VOC) i.e. propane, fed in mixture of oxygen. The VOC conversion (nearly 90%) obtained by varying the operating temperature showed that flow-through membrane reactor might do better in the abatement of VOCs.

Keywords: VOC combustion, flow-through membrane reactor, platinum supported alumina catalysts

Procedia PDF Downloads 537

Authors: Seyed Abolhasan Naeini, Mohammad Mahdi Shojaedin

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Oil leakage from the pipelines and the tanks carrying them, or during oil extraction, could lead to the changes in the characteristics and properties of the soil. In this paper, conducting a series of experimental cyclic triaxial tests, the effects of oil contamination on the liquefaction potential of sandy soils is investigated. The studied specimens are prepared by mixing the Firoozkuh sand with crude oil in 4, 8 and 12 percent by soil dry weight. The results show that the oil contamination up to 8% causes an increase in the soil liquefaction resistance and then with increase in the contamination, the liquefaction resistance decreases.

Keywords: cyclic triaxial test, liquefaction resistance, oil contamination, sandy soil

Procedia PDF Downloads 522

Authors: S. Manjunatha, M. S. Dharmaprakash

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Well-defined 2D Eu⁺³ co-doped ZrO₂: Gd⁺³ nanoparticles were successfully synthesized by microwave assisted solution combustion technique for luminescent applications. The present investigation reports the rapid and effective method for the synthesis of the Eu⁺³ co-doped ZrO₂:Gd⁺³ nanoparticles and study of the luminescence behavior of Eu⁺³ ion in ZrO₂:Gd⁺³ nanostructures. The optical properties of the prepared nanostructures were investigated by using UV-visible spectroscopy and photoluminescence spectra. The phase formation and the morphology of the nanoplatelets were studied by XRD, FESEM and HRTEM. The average grain size was found to be 45-50 nm. The presence of Gd³⁺ ion increases the crystallinity of the material and hence acts as a good nucleating agent. The ZrO₂:Gd³⁺ co-doped with Eu⁺³ nanoplatelets gives an emission at 607 nm, a strong red emission under the excitation wavelength of 255 nm.

Keywords: nanoparticles, XRD, TEM, photoluminescence

Procedia PDF Downloads 314