Search results for: PA doping ability

Authors: Hua Tan, David Salamon

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In this study, γ-Al2O3 powders doped with various amounts of iron were sintered via SPS process. Two heating modes – auto and manual mode were applied to observe the role of electrical induction on heating. Temperature, electric current, and pulse pattern were experimented with grade iron γ-Al2O3 powders. Phase transformation of γ to α -Al2O3 serves as a direct indicator of internal temperature, independently on measured outside temperature. That pulsing in SPS is also able to induce internal heating due to its strong electromagnetic field when dopants are conductive metals (e.g., iron) is proofed during SPS. Density and microstructure were investigated to explain the mechanism of induction heating. In addition, the role of electric pulsing and strong electromagnetic field on internal heating (induction heating) were compared and discussed. Internal heating by iron doping within electrically nonconductive samples is able to decrease sintering temperature and save energy, furthermore it is one explanation for unique features of this material fabrication technology.

Keywords: spark plasma sintering, induction heating, alumina, microstructure

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Authors: Wiqar Hussain Shah

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The electrical and thermal properties of the doped Tellurium Telluride (Tl10Te6) chalcogenide nano-particles are mainly characterized by a competition between metallic (hole doped concentration) and semi-conducting state. We have studied the effects of Sn doping on the electrical and thermoelectric properties of Tl10-xSnxTe6 (1.00 ≤x≤ 2.00), nano-particles, prepared by solid state reactions in sealed silica tubes and ball milling method. Structurally, all these compounds were found to be phase pure as confirmed by the x-rays diffractometery (XRD) and energy dispersive X-ray spectroscopy (EDS) analysis. Additionally crystal structure data were used to model the data and support the findings. The particles size was calculated from the XRD data by Scherrer’s formula. The EDS was used for an elemental analysis of the sample and declares the percentage of elements present in the system. The thermo-power or Seebeck co-efficient (S) was measured for all these compounds which show that S increases with increasing temperature from 295 to 550 K. The Seebeck coefficient is positive for the whole temperature range, showing p-type semiconductor characteristics. The electrical conductivity was investigated by four probe resistivity techniques revealed that the electrical conductivity decreases with increasing temperature, and also simultaneously with increasing Sn concentration. While for Seebeck coefficient the trend is opposite which is increases with increasing temperature. These increasing behavior of Seebeck coefficient leads to high power factor which are increases with increasing temperature and Sn concentration except For Tl8Sn2Te6 because of lowest electrical conductivity but its power factor increases well with increasing temperature.

Keywords: Sn doping in Tellurium Telluride nano-materials, electron holes competition, Seebeck co-efficient, effects of Sn doping on Electrical conductivity, effects on Power factor

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Authors: Swarnapriya Thiyagarajan, Modesto Antonio Sosa Aquino, Miguel Vallejo Hernandez, Senthilkumar Kalaiselvan Dhivyaraj, Jayaramakrishnan Velusamy

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In this paper the lithium tetra borate (Li2B4O7) was prepared by used water/solution assisted synthesis method. Once finished the synthesization, Copper (Cu) were used to doping material with Li2B4O7 in order to enhance its thermo luminescent properties. The heating temperature parameters were 750°C for 2 hr and 150°C for 2hr. The samples produced by water assisted method were doped at different doping percentage (0.02%, 0.04%, 0.06%, 0.08%, 0.12%, 0.5%, 0.1%, and 1%) of Cu.The characteristics and identification of Li2B4O7 (undoped and doped) were determined in four tests. They are X-ray diffraction (XRD), Scanning electron microscope (SEM), Photoluminescence (PL), Ultra violet visible spectroscopy (UV Vis). As it is evidence from the XRD and SEM results the obtained Li2B4O7 and Li2B4O7 doping with Cu was confirmed and also confirmed the chemical compositition and their morphologies. The obtained lithium tetraborate XRD pattern result was verified with the reference data of lithium tetraborate with tetragonal structure from JCPDS. The glow curves of Li2B4O7 and Li2B4O7 : Cu were obtained by thermo luminescence (TLD) reader (Harshaw 3500). The pellets were irradiated with different kind of dose (58mGy, 100mGy, 500mGy, and 945mGy) by using an X-ray source. Finally this energy response was also compared with TLD100. The order of kinetics (b), frequency factor (S) and activation energy (E) or the trapping parameters were calculated using peak shape method. Especially Li2B4O7: Cu (0.1%) presents good glow curve in all kind of doses. The experimental results showed that this Li2B4O7: Cu could have good potential applications in radiation dosimetry. The main purpose of this paper is to determine the effect of synthesis on the TL properties of doped lithium tetra borate Li2B4O7.

Keywords: dosimetry, irradiation, lithium tetraborate, thermoluminescence

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Authors: Michael Scott, Phil Jarrell

Abstract:

Digitalization seems to be everywhere these days. So if one was to digitalize Functional Safety, what would that require: • Ability to directly use data from intelligent P&IDs / process design in a PHA / LOPA • Ability to directly use data from intelligent P&IDs in the SIS Design to support SIL Verification Calculations, SRS, C&Es, Functional Test Plans • Ability to create Unit Operation / SIF Libraries to radically reduce engineering manhours while ensuring consistency and improving quality of SIS designs • Ability to link data directly from a PHA / LOPA to SIS Designs • Ability to leverage reliability models and SRS details from SIS Designs to automatically program the Safety PLC • Ability to leverage SIS Test Plans to automatically create Safety PLC application logic Test Plans for a virtual FAT • Ability to tie real-time data from Process Historians / CMMS to assumptions in the PHA / LOPA and SIS Designs to generate leading indicators on protection layer health • Ability to flag SIS bad actors for proactive corrective actions prior to a near miss or loss of containment event What if I told you all of this was available today? This paper will highlight how the digital revolution has revolutionized the way Safety Instrumented Systems are designed, configured, operated and maintained.

Keywords: IEC 61511, safety instrumented systems, functional safety, digitalization, IIoT

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Authors: Esmeralda Chávez Vargas, M. de la L. Olvera, A. Maldonado

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The doping it is believed as follows, at high concentration fluorine in ZnO: F films is incorporated to the lattice by substitution of O-2 ions by F-1 ions; at middle fluorine concentrations, F ions may form interstitials, whereas for low concentrations it is increased the carriers and mobility could be explained by the surface passivation effect of fluorine. ZnO:F thin films were deposited on sodocalcic glass substratesat 425 °C , 450°C, 475 during 8, 12, 15 min from a 0.2 M solution. Doping concentration in the starting solutions was varied, namely, [F]/[F+Zn] = 0, 5, 15, 30, 45, 60, and 90 at. %; solvent composition was varied as well, 100:100; 50:50; 100:50(acetic acid: water: methanol ratios, in volume). In this work it is reported the characterization results of fluorine doped zinc oxide (ZnO:F) thin films deposited by the ultrasonic spray pyrolysis technique, using zinc acetate and ammonium fluorine as Zn an F precursors, respectively. The effect of varying the fluorine concentration in the starting solutions, the solvent composition, and the ageing time of the starting solutions, on the electrical resistivity, optical transmittance, structure and surface morphology was analyzed. In order to have a quantitative evaluation of the ZnO:F thin films for its application as transparent electrodes, the Figure of Merit was estimated from the Haacke´s formula. After a thoroughly study, it can be found that optimal conditions for the deposition of transparent and conductive ZnO:F thin films on sodocalcic substrates, were as follows; substrate temperature: solution molar concentration 0.2, doping concentration in the starting solution of [F]/[Zn]= 60 at. %, (water content)/(acetic acid) in starting solution: [H2O/ CH3OH]= 50:50, substrate temperature: 450 °C. The effects of aging of the starting solution has also been analyzed thoroughly and it has been found a dramatic effect on the electric resistivity of the material, aged by 40 days, show an electrical resitivity as low as 120 Ω/□, with a transmittance around 80% in the visible range. X-ray diffraction spectra show a polycrystalline of ZnO (wurtzite structure) where the amount of fluorine doping affects to preferential orientation (002 plane). Therefore, F introduction in lattice is by the substitution of O-2 ions by F-1 ions. The results show that ZnO:F thin films are potentially adequate for application as transparent conductive oxide in thin film solar cells.

Keywords: TCOs, transparent electrodes, ultrasonic spray pyrolysis, zinc oxide, ZnO:F

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Authors: Kanlaya Ratanasuphakarn, Suttipong Boonphadung

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The research on the development of ability in reading comprehension based on metacognitive strategies aimed to (1) improve the students’development of ability in reading comprehension based on metacognitive strategies, (2) evaluate the students’ satisfaction on using metacognitive strategies in learning as a tool developing the ability in reading comprehension. Forty-eight of Mattayom 3 students who have enrolled in the subject of research for learning development of semester 2 in 2013 were purposively selected as the research cohort. The research tools were lesson plans for reading comprehension, pre-posttest and satisfaction questionnaire that were approved as content validity and reliability (IOC=.66-1.00,0.967). The research found that the development of ability in reading comprehension of the research samples before using metacognitive strategies in learning activities was in the normal high level. Additionally, the research discovered that the students’ satisfaction of the research cohort after applying model in learning activities appeared to be high level of satisfaction on using metacognitive strategies in learning as a tool for the development of ability in reading comprehension.

Keywords: development of ability, metacognitive strategies, satisfaction, reading comprehension

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Authors: Akbar Rostamabadi, Adel Mazloumi, Abbas Rahimi Foroushani

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This study aimed to determine the Work Ability Index (WAI) and examine the influence of health dimensions and demographic variables on the work ability of Iranian farmers working in small farm enterprises. A cross-sectional study was conducted among 294 male farmers. The WAI and SF-36 questionnaires were used to determine work ability and health status. The effect of demographics variables on the work ability index was investigated with the independent samples t-test and one-way ANOVA. Also, multiple linear regression analysis was used to test the association between the mean WAI score and the SF-36 scales. The mean WAI score was 35.1 (SD=10.6). One-way ANOVA revealed a significant relationship between the mean WAI and age. Multiple linear regression analysis showed that work ability was more influenced by physical scales of the health dimensions, such as physical function, role-physical, and general health, whereas a lower association was found for mental scales such as mental health. The average WAI was at a moderate work ability level for the sample population of farmers in this study. Based on the WAI guidelines, improvement of work ability and identification of factors affecting it should be considered a priority in interventional programs. Given the influence of health dimensions on WAI, any intervention program for preservation and promotion work ability among the studied farmers should be based on balancing and optimizing the physical and psychosocial work environments, with a special focus on reducing physical work load.

Keywords: farmers, SF-36, Work Ability Index (WAI), Iran

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Authors: Ali Ballouch, Nourelhouda Choukri, Zouhair Soufiani, Mohamed El Jouad, Mohamed Addou

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For several years, significant research has been developed in the areas of applications of semiconductor wide bandgap such as ZnO in optoelectronics. This oxide has the advantage of having a large exciton energy (60 meV) three times higher than that of GaN (21 meV) or ZnS (20 meV). This energy makes zinc oxide resistant for laser irradiations and very interesting for the near UV-visible optic, as well as for studying physical microcavities. A high-energy direct gap at room temperature (Eg > 1 eV) which makes it a potential candidate for emitting devices in the near UV and visible. Our work is to study the nonlinear optical properties, mainly the nonlinear third-order susceptibility of europium doped Zinc oxide thin films. The samples were prepared by chemical vapor spray method (Spray), XRD, SEM technique, THG were used for characterization. In this context, the influence of europium doping on the nonlinear optical response of the Zinc oxide was investigated. The nonlinear third-order properties depend on the physico-chemical parameters (crystallinity, strain, and surface roughness), the nature and the level of doping, temperature.

Keywords: ZnO, characterization, non-linear optical properties, optoelectronics

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Authors: Omar Al Ali

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The current study was aimed to explore the relationships between emotional intelligence, cognitive ability, and leader's performance. Data were collected from 260 senior managers from UAE. The results showed that there are significant relationships between emotional intelligence and leadership performance as measured by the annual internal evaluations of each participant (r = .42, p < .01). Data from regression analysis revealed that both variables namely emotional intelligence (beta = .31, p < .01), and cognitive ability (beta = .29, p < .01), predicted leadership competencies, and together explained 26% of its variance. Data suggests that EI and cognitive ability are significantly correlated with leadership performance. In depth implications of the present findings for human resource development theory and practice are discussed.

Keywords: emotional intelligence, cognitive ability, leadership, performance

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Authors: Franco Bruno Castaldo

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Aim: The term bioethics is a term coined by VanPotter R ., who in 1970 thought of a discipline, capable of contributing to a better quality of human life and the cosmos. At first he intended bioethics as a wisdom capable of creating a bridge between bios and ethos and between bio-experimental science and ethical-anthropological sciences.Similarly, the modern sport is presented as a polysemic phenomenon, multidisciplinary, pluris value. From the beginning, the sport is included in the discussion of bioethical problems with doping. Today, the ethical problems of the sport are not only ascribable to doping, the medicalization of society, Techniques for enhancement, violence, Fraud, corruption, even the acceptance of anthropological transhumanist theories. Our purpose is to shed light on these issues so that there is a discernment, a fine-tuning also in educational programs, for the protection of all the sport from a scientist adrift, which would lead to an imbalance of values. Method: Reading, textual and documentary analysis, evaluation of critical examples. Results: Harold VanderZwaag, (1929-2011) in ancient times, asked: how many athletic directors have read works of sport philosophy or humanities? Along with E.A. Zeigler (North American Society for Sport Management) are recognized as pioneers of educational Sport Management. Comes the need to leave the confines of a scientific field, In order to deal with other than itself. Conclusion: The quantitative sciences attracts more funds than qualitative ones, the philosopher M. Nussbaum, has relaunched the idea that the training of students will have to be more disinterested than utilitarian, Offering arguments against the choice of anti-classical, analyzing and comparing different educational systems. schools, universities must assign a prominent place in the program of study to the humanistic, literary and artistic subjects, cultivating a participation that can activate and improve the ability to see the world through the eyes of another person. In order to form citizens who play their role in society, science and technology alone are not enough, we need disciplines that are able to cultivate critical thinking, respect for diversity, solidarity, the judgment, the freedom of expression. According to A. Camelli, the humanities faculties prepare for that life-long learning, which will characterize tomorrow's jobs.

Keywords: bioethics, management, sport, transhumanist, medicalization

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Authors: Chongsutthamani Sitthiwet, Praphatsorn Plerdsranoy, Palmarin Dansirima, Priew Eiamlamai, Oliver Utke, Rapee Utke

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Hydrogen storage tank containing compacted LiNH2-LiH is developed by doping with TiF₄ and multi-walled nanotubes (MWCNTs) to study kinetic properties. Transition metal-based catalyst (TiF₄) provides the catalytic effect on hydrogen dissociation/recombination, while MWCNTs benefit thermal conductivity and hydrogen permeability during de/rehydrogenation process. The Enhancement of dehydrogenation kinetics is observed from the single-step reaction at a narrower and lower temperature range of 150-350 ºC (100 ºC lower than the compacted LiNH₂-LiH without additives) as well as long plateau temperature and constant hydrogen flow rate (50 SCCM) up to 30 min during desorption. Besides, Hydrogen contents de/absorbed during 5-6 cycles increase from 1.90-2.40 to 3.10-4.70 wt. % H₂ (from 29 to up to 80 % of theoretical capacity). In the process, Li₅TiN₃ is detected upon cycling probably absorbs NH₃ to form Li₅TiN₃(NH₃)x, which is favoring hydrogen sorption properties of the LiNH₂-LiH system. Importantly, the homogeneous reaction mechanisms and performances are found at all positions inside the tank of compacted LiNH₂-LiH doped with TiF₄ and MWCNTs.

Keywords: carbon, hydride, kinetics, dehydrogenation

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Authors: Bikram K. Das, Kalyan K. Chattopadhyay

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The advent of 2-D materials in the last decade has induced a fresh spur of growth in fuel cell technology as these materials have some highly promising traits that can be exploited to felicitate Oxygen Reduction Reaction (ORR) in an efficient way. Among the various 2-D carbon materials, graphyne (Gy) and graphdiyne (Gdy)1 with their intrinsic non-uniform charge distribution holds promises in this purpose and it is expected2 that substitutional Nitrogen (N) doping could further enhance their efficiency. In this regard, dispersive force corrected density functional theory is used to map the oxygen reduction reaction (ORR) kinetics of five different kinds of N doped graphyne and graphdiyne systems (namely αGy, βGy, γGy, RGy and 6,6,12Gy and Gdy) in alkaline medium. The best doping site for each of the Gy/ Gdy system is determined comparing the formation energies of the possible doping configurations. Similarly, the best di-oxygen (O₂) adsorption sites for the doped systems are identified by comparing the adsorption energies. O₂ adsorption on all N doped Gy/ Gdy systems is found to be energetically favorable. ORR on a catalyst surface may occur either via the Eley-Rideal (ER) or the Langmuir–Hinschelwood (LH) pathway. Systematic studies performed on the considered systems reveal that all of them favor the ER pathway. Further, depending on the nature of di-oxygen adsorption ORR can follow either associative or dissociative mechanism; the possibility of occurrence of both the mechanisms is tested thoroughly for each N doped Gy/ Gdy. For the ORR process, all the Gy/Gdy systems are observed to prefer the efficient four-electron pathway but the expected monotonically exothermic reaction pathway is found only for N doped 6,6,12Gy and RGy following the associative pathway and for N doped βGy, γGy and Gdy following the dissociative pathway. Further computation performed for these systems reveals that for N doped 6,6,12Gy, RGy, βGy, γGy and Gdy the overpotentials are 1.08 V, 0.94 V, 1.17 V, 1.21 V and 1.04 V respectively depicting N doped RGy is the most promising material, to carry out ORR in alkaline medium, among the considered ones. The stability of the ORR intermediate states with the variation of pH and electrode potentials is further explored with Pourbiax diagrams and the activities of these systems in the alkaline medium are compared with the prior reported B/N doped identical systems for ORR in an acidic medium in terms of a common descriptor.

Keywords: graphdiyne, graphyne, nitrogen-doped, ORR

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Authors: Djaafar F., Hadri B., Bachir G.

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We studied mainly the influence of temperature, thickness, molar fraction and the doping of the various layers (emitter, base, BSF and window) on the performances of a photovoltaic solar cell. In a first stage, we optimized the performances of the InGaP/GaAs dual-junction solar cell while varying its operation temperature from 275°K to 375 °K with an increment of 25°C using a virtual wafer fabrication TCAD Silvaco. The optimization at 300°K led to the following result Icc =14.22 mA/cm2, Voc =2.42V, FF =91.32 %, η = 22.76 % which is close with those found in the literature. In a second stage ,we have varied the molar fraction of different layers as well their thickness and the doping of both emitters and bases and we have registered the result of each variation until obtaining an optimal efficiency of the proposed solar cell at 300°K which was of Icc=14.35mA/cm2,Voc=2.47V,FF=91.34,and η =23.33% for In(1-x)Ga(x)P molar fraction( x=0.5).The elimination of a layer BSF on the back face of our cell, enabled us to make a remarkable improvement of the short-circuit current (Icc=14.70 mA/cm2) and a decrease in open circuit voltage Voc and output η which reached 1.46V and 11.97% respectively. Therefore, we could determine the critical parameters of the cell and optimize its various technological parameters to obtain the best performance for a dual junction solar cell. This work opens the way with new prospects in the field of the photovoltaic one. Such structures will thus simplify the manufacturing processes of the cells; will thus reduce the costs while producing high outputs of photovoltaic conversion.

Keywords: modeling, simulation, multijunction, optimization, silvaco ATLAS

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Authors: Sibel Daglilar, Isil Kerti, Murat Karagoz, Fatih Dumludag, Oguzhan Gunduz, Faik Nuzhet Oktar

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Hydroxyapatite (HA) materials have common use in bone repairing due to its ability to accelerate the bone growth around the implant. In spite of being a biocompatible and bioactive material, HA has a limited usage as an implant material because of its weak mechanical properties. HA based composites are required to improve the strength and toughness properties of the implant materials without compromising of biocompatibility. The excellent mechanical properties and higher biocompatibilities are expected from each of biomedical composites. In this study, HA composites were synthesized by using bovine bone reinforced doped with different amount of (wt.%) Li2O. The pressed pellets were sintered at various sintering temperatures between 1000ºC and 1300°C, and mechanical, electrical properties of the obtained products were characterized. In addition to that, in vitro stimulated body fluid (SBF) tests for these samples were conducted. The most suitable composite composition for biomedical applications was discussed among the composites studied.

Keywords: biocomposites, sintering temperature, biocompatibility, electrical property, conductivity, mechanical property

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Authors: Yasar N. Kavil, Yasser A. Shaban, Radwan K. Al Farawati, Mohamed I. Orif, Shahed U. M. Khanc

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Photocatalytic way of reduction of CO₂ in polluted seawater into chemical fuel, methanol, was successfully gained over Cu/C-co-doped TiO₂ nanoparticles under UV and natural sunlight. A homemade stirred batch annular reactor was used to carry out the photocatalytic reduction experiments. Photocatalysts with various Cu loadings (0, 0.5, 1, 3, 5 and 7 wt.%) were synthesized by the sol-gel procedure and were characterized by XRD, SEM, UV–Vis, FTIR, and XPS. The photocatalytic production of methanol was promoted by the co-doping with C and Cu into TiO₂. This improvement was attributed to the modification of bandgap energy and the hindrance of the charges recombination. The polluted seawater showing the yield depended on its background hydrographic parameters. We assessed two types of polluted seawater system, the observed yield was 2910 and 990 µmol g⁻¹ after 5 h of illumination under UV and natural sunlight respectively in system 1 and the corresponding yield in system 2 was 2250 and 910 µmol g⁻¹ after 5 h of illumination. The production of methanol in the case of oxygen-depleted water was low, this is mainly attributed to the competition of methanogenic bacteria over methanol production. The results indicated that the methanol yield produced by Cu-C/TiO₂ was much higher than those of carbon-modified titanium oxide (C/TiO₂) and Degussa (P25-TiO₂). Under the current experimental condition, the optimum loading was achieved by the doping of 3 wt % of Cu. The highest methanol yield was obtained over 1 g L-1 of 3wt% Cu/C-TiO₂.

Keywords: CO₂ photoreduction, copper, Cu/C-co-doped TiO₂, methanol, seawater

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Authors: J. Das, T. S. Mahule, V. V. Srinivasu

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Electron spin resonance (ESR) study at 9.45 GHz and a field modulation frequency of 100Hz was performed on bulk polycrystalline samples of Mn:TM (Fe/Ni) and Mn:RE (Gd/Sm) co doped ZnO samples with composition Zn1-xMn:TM/RE)xO synthesised by solid state reaction route and sintered at 500 0C temperature. The room temperature microwave absorption data collected by sweeping the DC magnetic field from -500 to 9500 G for the Mn:Fe and Mn:Ni co doped ZnO samples exhibit a rarely reported non resonant low field absorption (NRLFA) in addition to a strong absorption at around 3350G, usually associated with ferromagnetic resonance (FMR) satisfying Larmor’s relation due to absorption in the full saturation state. Observed low field absorption is distinct to ferromagnetic resonance even at low temperature and shows hysteresis. Interestingly, it shows a phase opposite with respect to the main ESR signal of the samples, which indicates that the low field absorption has a minimum value at zero magnetic field whereas the ESR signal has a maximum value. The major resonance peak as well as the peak corresponding to low field absorption exhibit asymmetric nature indicating magnetic anisotropy in the sample normally associated with intrinsic ferromagnetism. Anisotropy parameter for Mn:Ni codoped ZnO sample is noticed to be quite higher. The g values also support the presence of oxygen vacancies and clusters in the samples. These samples have shown room temperature ferromagnetism in the SQUID measurement. However, in rare earth (RE) co doped samples (Zn1-x (Mn: Gd/Sm)xO), which show paramagnetic behavior at room temperature, the low field microwave signals are not observed. As microwave currents due to itinerary electrons can lead to ohmic losses inside the sample, we speculate that more delocalized 3d electrons contributed from the TM dopants facilitate such microwave currents leading to the loss and hence absorption at the low field which is also supported by the increase in current with increased micro wave power. Besides, since Fe and Ni has intrinsic spin polarization with polarisability of around 45%, doping of Fe and Ni is expected to enhance the spin polarization related effect in ZnO. We emphasize that in this case Fe and Ni doping contribute to polarized current which interacts with the magnetization (spin) vector and get scattered giving rise to the absorption loss.

Keywords: co-doping, electron spin resonance, hysteresis, non-resonant microwave absorption

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Authors: Djaafar Fatiha, Ghalem Bachir, Hadri Bagdad

Abstract:

We studied mainly the influence of temperature, thickness, molar fraction and the doping of the various layers (emitter, base, BSF and window) on the performances of a photovoltaic solar cell. In a first stage, we optimized the performances of the InGaP/GaAs dual-junction solar cell while varying its operation temperature from 275°K to 375 °K with an increment of 25°C using a virtual wafer fabrication TCAD Silvaco. The optimization at 300 °K led to the following result: Icc =14.22 mA/cm2, Voc =2.42V, FF=91.32 %, η= 22.76 % which is close with those found in the literature. In a second stage ,we have varied the molar fraction of different layers as well their thickness and the doping of both emitters and bases and we have registered the result of each variation until obtaining an optimal efficiency of the proposed solar cell at 300°K which was of Icc=14.35mA/cm2,Voc=2.47V,FF=91.34,and η=23.33% for In(1-x)Ga(x)P molar fraction( x=0.5).The elimination of a layer BSF on the back face of our cell, enabled us to make a remarkable improvement of the short-circuit current (Icc=14.70 mA/cm2) and a decrease in open circuit voltage Voc and output η which reached 1.46V and 11.97% respectively. Therefore, we could determine the critical parameters of the cell and optimize its various technological parameters to obtain the best performance for a dual junction solar cell .This work opens the way with new prospects in the field of the photovoltaic one. Such structures will thus simplify the manufacturing processes of the cells; will thus reduce the costs while producing high outputs of photovoltaic conversion.

Keywords: modeling, simulation, multijunction, optimization, Silvaco ATLAS

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Authors: Suraka Bhattacharjee, Ranjan Chaudhury

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The interaction between the charge degrees of freedom for itinerant antiferromagnets is investigated in terms of generalized charge stiffness constant corresponding to nearest neighbour t-J model and t1-t2-t3-J model. The low dimensional hole doped antiferromagnets are the well known systems that can be described by the t-J-like models. Accordingly, we have used these models to investigate the fermionic pairing possibilities and the coupling between the itinerant charge degrees of freedom. A detailed comparison between spin and charge couplings highlights that the charge and spin couplings show very similar behaviour in the over-doped region, whereas, they show completely different trends in the lower doping regimes. Moreover, a qualitative equivalence between generalized charge stiffness and effective Coulomb interaction is also established based on the comparisons with other theoretical and experimental results. Thus it is obvious that the enhanced possibility of fermionic pairing is inherent in the reduction of Coulomb repulsion with increase in doping concentration. However, the increased possibility can not give rise to pairing without the presence of any other pair producing mechanism outside the t-J model. Therefore, one can conclude that the t-J-like models themselves solely are not capable of producing conventional momentum-based superconducting pairing on their own.

Keywords: generalized charge stiffness constant, charge coupling, effective Coulomb interaction, t-J-like models, momentum-space pairing

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Authors: Kwangwon Seo, Haksoo Han

Abstract:

Al-Si was synthesized and introduced in poly 2,2’-m-(phenylene)-5,5’-bibenzimidazole (PBI). As a result, a series of five Al-Si/PBI composite (ASPBI) membranes (0, 3, 6, 9, and 12 wt.%) were developed and characterized for application in high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). The chemical and morphological structure of ASPBI membranes were analyzed by Fourier transform infrared spectroscopy, X-ray diffractometer and scanning electron microscopy. According to the doping level test and thermogravimetric analysis, as the concentration of Al-Si increased, the doping level increased up to 475%. Moreover, the proton conductivity, current density at 0.6V, and maximum power density of ASPBI membranes increased up to 0.31 Scm-1, 0.320 Acm-2, and 0.370 Wcm-2, respectively, because the increased concentration of Al-Si allows the membranes to hold more PA. Alternatively, as the amount of Al-Si increased, the tensile strength of PA-doped and -undoped membranes decreased. This was resulted by both excess PA and aggregation, which can cause serious degradation of the membrane and induce cracks. Moreover, the PA-doped and -undoped ASPBI12 had the lowest tensile strength. The improved performances of ASPBI membranes imply that ASPBI membranes are possible candidates for HT-PEMFC applications. However, further studies searching to improve the compatibility between PBI matrix and inorganic and optimize the loading of Al-Si should be performed.

Keywords: composite membrane, high temperature polymer electrolyte membrane fuel cell, membrane electrode assembly, polybenzimidazole, polymer electrolyte membrane, proton conductivity

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Authors: Girish Sambhaji Gund

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The controlled nanostructure growth and its strong coupling with the current collector are key factors to achieve good electrochemical performance of faradaic-dominant electroactive materials. We employed binder-less and additive-free hydrothermal and physical vapor doping methods for the synthesis of nickel (Ni) and cobalt (Co) based compounds nanostructures (NiO, NiCo2O4, NiCo2S4) deposited on different conductive substrates such as carbon nanotube (CNT) on stainless steel, and reduced graphene oxide (rGO) and N-doped rGO on nickel foam (NF). The size and density of Ni- and Co-based compound nanostructures are controlled through the strong coupling with carbon allotropes on stainless steel and NF substrates. This controlled nanostructure of Ni- and Co-based compounds with carbon allotropes leads to stable faradaic electrochemical reactions at the material/current collector interface and within the electrode, which is consequence of strong coupling of nanostructure with functionalized carbon surface as a buffer layer. Thus, it is believed that the results provide the synergistic approaches to stabilize electrode materials physically and chemically, and hence overall electrochemical activity of faradaic dominating battery-type electrode materials through buffer layer engineering.

Keywords: metal compounds, carbon allotropes, doping, electrochemicstry, hybrid supercapacitor

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Authors: J. P. Borah, R. D. Raland

Abstract:

Hyperthermia is one of many techniques used destroys cancerous cell. It uses the physical methods to heat certain organ or tissue delivering an adequate temperature in an appropriate period of time, to the entire tumor volume for achieving optimal therapeutic results. Magnetic Metal ferrites nanoparticles (MFe₂O₄ where M = Mn, Zn, Ni, Co, Mg, etc.) are one of the most potential candidates for hyperthermia due to their tunability, biocompatibility, chemical stability and notable ability to mediate high rate of heat induction. However, to obtain the desirable properties for these applications, it is important to optimize their chemical composition, structure and magnetic properties. These properties are mainly sensitive to cation distribution of tetrahedral and octahedral sites. Among the ferrites, zinc ferrite (ZnFe₂O₄) and Manganese ferrite ((MnFe₂O₄) is one of a strong candidate for hyperthermia application because Mn and zinc have a non-magnetic cation and therefore the magnetic property is determined only by the cation distribution of iron, which provides a better platform to manipulate or tailor the properties. In this talk, influence of doping and surfactant towards cation re-distribution leading to an enhancement of magnetic properties of ferrite nanoparticles will be demonstrated. The efficiency of heat generation in association with the enhanced magnetic property is also well discussed in this talk.

Keywords: magnetic nanoparticle, hyperthermia, x-ray diffraction, TEM study

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Authors: Xiao-Mei Zhang, Sian-Hong Tseng, Ming-Yen Lu

Abstract:

Two-dimensional (2D) transition metal dichalcogenides (TMDCs), such as MoS₂, have attracted considerable attention owing to the unique optical and electronic properties related to its 2D ultrathin atomic layer structure. MoS₂ is becoming prevalent in post-silicon digital electronics and in highly efficient optoelectronics due to its extremely low thickness and its tunable band gap (Eg = 1-2 eV). For low-power, high-performance complementary logic applications, both p- and n-type MoS₂ FETs (NFETs and PFETs) must be developed. NFETs with an electron accumulation channel can be obtained using unintentionally doped n-type MoS₂. However, the fabrication of MoS₂ FETs with complementary p-type characteristics is challenging due to the significant difficulty of injecting holes into its inversion channel. Plasma treatments with different species (including CF₄, SF₆, O₂, and CHF₃) have also been found to achieve the desired property modifications of MoS₂. In this work, we demonstrated a p-type multilayer MoS₂ enabled by selective-area doping using CHF₃ plasma treatment. Compared with single layer MoS₂, multilayer MoS₂ can carry a higher drive current due to its lower bandgap and multiple conduction channels. Moreover, it has three times the density of states at its minimum conduction band. Large-area growth of MoS₂ films on 300 nm thick SiO₂/Si substrate is carried out by thermal decomposition of ammonium tetrathiomolybdate, (NH₄)₂MoS₄, in a tube furnace. A two-step annealing process is conducted to synthesize MoS₂ films. For the first step, the temperature is set to 280 °C for 30 min in an N₂ rich environment at 1.8 Torr. This is done to transform (NH₄)₂MoS₄ into MoS₃. To further reduce MoS₃ into MoS₂, the second step of annealing is performed. For the second step, the temperature is set to 750 °C for 30 min in a reducing atmosphere consisting of 90% Ar and 10% H₂ at 1.8 Torr. The grown MoS₂ films are subjected to out-of-plane doping by CHF₃ plasma treatment using a Dry-etching system (ULVAC original NLD-570). The radiofrequency power of this dry-etching system is set to 100 W and the pressure is set to 7.5 mTorr. The final thickness of the treated samples is obtained by etching for 30 s. Back-gated MoS₂ PFETs were presented with an on/off current ratio in the order of 10³ and a field-effect mobility of 65.2 cm²V⁻¹s⁻¹. The MoS₂ PFETs photodetector exhibited ultraviolet (UV) photodetection capability with a rapid response time of 37 ms and exhibited modulation of the generated photocurrent by back-gate voltage. This work suggests the potential application of the mild plasma-doped p-type multilayer MoS₂ in UV photodetectors for environmental monitoring, human health monitoring, and biological analysis.

Keywords: photodetection, p-type doping, multilayers, MoS₂

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Authors: G. Nyongombe, Guy L. Kabongo, B. M. Mothudi, M. S. Dhlamini

Abstract:

A series of Transition Metals Oxides (TMOs) doped graphene were synthesized and successfully used as supercapacitor electrode materials. The as-synthesized materials exhibited exceptional electrochemical properties owing to the combined properties of its constituents; high surface area and good conductivity were achieved. Several analytical characterization techniques were employed to investigate the morphology, crystal structure atomic arrangement and elemental chemical state in the materials for which scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were conducted, respectively. Moreover, the electrochemical properties of the as-synthesized materials were examined by performing cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements. Furthermore, the effect of doping concentration on the interlayer distance of the graphene materials and the charge transfer resistance are investigated and correlated to the exceptional current density which was multiplied by a factor of ~80 after TMOs doping in graphene. Finally, the resulting high capacitance obtained confirms the contribution of grapheme exceptional electronic conductivity and large surface area on the electrode materials. Such good-performing electrode materials are highly promising for supercapacitors and other energy storage devices.

Keywords: energy density, graphene, supercapacitors, TMOs

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Authors: Ai Chin Wong, Wan Ahmad Jaafar Wan Yahaya, Balakrishnan Muniandy

Abstract:

This study aims to explore the impact of Virtual Reality (VR) using visual signaling principles in learning about the science laboratory safety guide; this study involves students with different spatial ability. There are two types of science laboratory safety lessons, which are Virtual Reality with Signaling (VRS) and Virtual Reality Non Signaling (VRNS). This research has adopted a 2 x 2 quasi-experimental factorial design. There are two types of variables involved in this research. The two modes of courseware form the independent variables with the spatial ability as the moderator variable. The dependent variable is the students’ performance. This study sample consisted of 141 students. Descriptive and inferential statistics were conducted to analyze the collected data. The major effects and the interaction effects of the independent variables on the independent variable were explored using the Analyses of Covariance (ANCOVA). Based on the findings of this research, the results exhibited low spatial ability students in VRS outperformed their counterparts in VRNS. However, there was no significant difference in students with high spatial ability using VRS and VRNS. Effective learning in students with different spatial ability can be boosted by implementing the Virtual Reality with Signaling (VRS) in the design as well as the development of Virtual Science Laboratory (ViSLab).

Keywords: spatial ability, science laboratory safety, visual signaling principles, virtual reality

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Authors: Zeinab Zaremohzzabieh, Syasya Firzana Azmi, Haslinda Abdullah, Soh Kim Geok, Aini Azeqa Ma'rof, Hayrol Azril Mohammed Shaffril

Abstract:

The escalating prevalence of doping in sports, casting a shadow over both high-performance and recreational settings, has emerged as a formidable concern, particularly within the realm of young athletes. Doping, characterized by the surreptitious use of prohibited substances to gain a competitive edge, underscores the pressing need for comprehensive and efficacious preventive measures. This study aims to address a crucial void in current research by unraveling the motivations that drive clean adolescent athletes to steadfastly abstain from performance-enhancing substances. In navigating this intricate landscape, the study adopts a positive psychology perspective, investigating into the conditions and processes that contribute to the holistic well-being of individuals and communities. At the heart of this exploration lies the application of the PERMA model, a comprehensive positive psychology framework encapsulating positive emotion, engagement, relationships, meaning, and accomplishments. This model functions as a distinctive lens, dissecting intervention results to offer nuanced insights into the complex dynamics of clean sport behavior. The research is poised to usher in a paradigm shift from conventional anti-doping strategies, predominantly fixated on identifying deficits, towards an innovative approach firmly rooted in positive psychology. The objective of this study is to evaluate the efficacy of a positive education intervention program tailored to promote clean sport behavior among Malaysian adolescent athletes. Representing unexplored terrain within the landscape of anti-doping efforts, this initiative endeavors to reshape the focus from deficiencies to strengths. The meticulously crafted pilot study engages thirty adolescent athletes, divided into a control group of 15 and an experimental group of 15. The pilot study serves as the crucible to assess the effectiveness of the prepared intervention package, providing indispensable insights that will meticulously guide the finalization of an all-encompassing intervention program for the main study. The main study adopts a pioneering two-arm randomized control trial methodology, actively involving adolescent athletes from diverse Malaysian high schools. This approach aims to address critical lacunae in anti-doping strategies, specifically calibrated to resonate with the unique context of Malaysian schools. The study, cognizant of the imperative to develop preventive measures harmonizing with the cultural and educational milieu of Malaysian adolescent athletes, aspires to cultivate a culture of clean sport. In conclusion, this research aspires to contribute unprecedented insights into the efficacy of positive education interventions firmly rooted in the PERMA model. By unraveling the intricacies of clean sport behavior, particularly within the context of Malaysian adolescent athletes, the study seeks to introduce transformative preventive methods. The adoption of positive psychology as an avant-garde anti-doping tool represents an innovative and promising approach, bridging a conspicuous gap in scholarly research and offering potential panaceas for the sporting community. As this study unfurls its chapters, it carries the promise not only to enrich our understanding of clean sport behavior but also to pave the way for positive metamorphosis within the realm of adolescent sports in Malaysia.

Keywords: positive education interventions, a pilot study, clean sport behavior, adolescent athletes, Malaysia

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Authors: Victor William Harris

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This research is a validation study of the Social Emotional Ability Inventory (SEAI), a multi-dimensional self-report instrument informed by positive psychology, emotional intelligence, social intelligence, and sociocultural learning theory. Designed for use in tandem with the Social Emotional Development (SEAD) theoretical model, the SEAI provides diagnostic-level guidance for professionals and individuals interested in investigating, identifying, and understanding social, emotional strengths, as well as remediating specific social competency deficiencies. The SEAI was shown to be psychometrically sound, exhibited strong internal reliability, and supported the a priori hypotheses of the SEAD. Additionally, confirmatory factor analysis provided evidence of goodness of fit, convergent and divergent validity, and supported a theoretical model that reflected SEAD expectations. The SEAI and SEAD hold potentially far-reaching and important practical implications for theoretical guidance and diagnostic-level measurement of social, emotional competency across a wide range of domains. Strategies researchers, practitioners, educators, and individuals might use to deploy SEAI in order to improve quality of life outcomes are discussed.

Keywords: emotion, emotional ability, positive psychology-social emotional ability, social emotional ability, social emotional ability instrument

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Authors: Anna Krukowska, Tomasz Klimczuk, Adriana Zaleska-Medynska

Abstract:

Photoactive materials have attracted attention due to their potential application in the degradation of environmental pollutants to non-hazardous compounds in an eco-friendly route. Among semiconductor photocatalysts, tantalates such as potassium tantalate (KTaO3) is one of the excellent functional photomaterial. However, tantalates-based materials are less active under visible-light irradiation, the enhancement in photoactivity could be improved with the modification of opto-eletronic properties of KTaO3 by doping rare earth metal (Er) and further photodeposition of noble metal nanoparticles (Pt). Inclusion of rare earth element in orthorhombic structure of tantalate can generate one high-energy photon by absorbing two or more incident low-energy photons, which convert visible-light and infrared-light into the ultraviolet-light to satisfy the requirement of KTaO3 photocatalysts. On the other hand, depositions of noble metal nanoparticles on the surface of semiconductor strongly absorb visible-light due to their surface plasmon resonance, in which their conducting electrons undergo a collective oscillation induced by electric field of visible-light. Furthermore, the high dispersion of Pt nanoparticles, which will be obtained by photodeposition process is additional important factor to improve the photocatalytic activity. The present work is aimed to study the effect of photocatalytic process of the prepared Er-doped KTaO3 and further incorporation of Pt nanoparticles by photodeposition. Moreover, the research is also studied correlations between photocatalytic activity and physico-chemical properties of obtained Pt/Er-KTaO3 samples. The Er-doped KTaO3 microcomposites were synthesized by a hydrothermal method. Then photodeposition method was used for Pt loading over Er-KTaO3. The structural and optical properties of Pt/Er-KTaO3 photocatalytic were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), volumetric adsorption method (BET), UV-Vis absorption measurement, Raman spectroscopy and luminescence spectroscopy. The photocatalytic properties of Pt/Er-KTaO3 microcomposites were investigated by degradation of phenol in aqueous phase as model pollutant under visible and ultraviolet-light irradiation. Results of this work show that all the prepared photocatalysis exhibit low BET surface area, although doping of the bare KTaO3 with rare earth element (Er) presents a slight increase in this value. The crystalline structure of Pt/Er-KTaO3 powders exhibited nearly identical positions for the main peak at about 22,8o and the XRD pattern could be assigned to an orthorhombic distorted perovskite structure. The Raman spectra of obtained semiconductors confirmed demonstrating perovskite-like structure. The optical absorption spectra of Pt nanoparticles exhibited plasmon absorption band for main peaks at about 216 and 264 nm. The addition of Pt nanoparticles increased photoactivity compared to Er-KTaO3 and pure KTaO3. Summary optical properties of KTaO3 change with its doping Er-element and further photodeposition of Pt nanoparticles.

Keywords: heterogeneous photocatalytic, KTaO3 photocatalysts, Er3+ ion doping, Pt photodeposition

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Authors: A. Juhász, M. Fogarasi

Abstract:

Those causing fatal traffic accidents are traumatized, which negatively influences their cognitive functions and their personality. In order to clarify how much the trauma of causing a fatal accident effects their driving skills and personality traits, the results of a psychological aptitude and a personality test of drivers carelessly causing fatal accidents and of drivers not causing any accidents were compared separately. The sample (N = 354) consists of randomly selected drivers from the Transportation Aptitude and Examination Centre database who caused fatal accidents (Fatal group, n = 177) or did not cause accidents (Control group, n = 177). The aptitude tests were taken between 2014 and 2019. The comparison of the 2 groups was done according to 3 aspects: 1. Categories of aptitude (suitable, restricted, unsuited); 2. Categories of causes (ability, personality, ability and personality) within the restricted or unsuited (altogether: non-suitable subgroups); 3. Categories of ability and personality within the non-suitable subgroups regardless of the cause-category. Within ability deficiency, the two groups include those, whose ability factor is impaired or limited. This is also true in case of personality failure. Compared to the control group, the number of restricted drivers causing fatal accidents is significantly higher (p < .000) and the number of unsuited drivers is higher on a tendency-level (p = .06). Compared to the control group in the fatal non-suitable subgroup, the ratio of restricted suitability and the unsuitability due to ability factors is exclusively significantly lower (p < .000). The restricted suitability and the unsuitability due to personality factors are more significant in the fatal non-suitable subgroup (p < .000). Incapacity due to combination of ability and personality is also significantly higher in the fatal group (p = .002). Compared to the control group both ability and personality factors are also significantly higher in the fatal non-suitable subgroup (p < .000). Overall, the control group is more eligible for driving than drivers who have caused fatalities. The ability and personality factors are significantly higher in the case of fatal accident causers who are non-suitable for driving. Moreover the concomitance of ability and personality factors occur almost exclusively to drivers who caused fatal accidents. Further investigation is needed to understand the causes and how the aptitude test results for the fatal group could improve over time.

Keywords: aptitude, unsuited, fatal accident, ability, personality

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Authors: Elvira Wahyuni

Abstract:

This study is a classroom action research. The general objective of this study was to find out students’ speaking ability through teaching English by using video and to find out the effectiveness of using video in teaching English to improve students’ speaking ability. The subjects of this study were 34 of the first-year students of SMAN 12 Pekanbaru who were learning English as a foreign language (EFL). Students were given pre-test before the treatment and post-test after the treatment. Quantitative data was collected by using speaking test requiring the students to respond to the recorded questions. Qualitative data was collected through observation sheets and field notes. The research finding reveals that there is a significant improvement of the students’ speaking ability through the use of video in speaking class. The qualitative data gave a description and additional information about the learning process done by the students. The research findings indicate that the use of video in teaching and learning is good in increasing learning outcome.

Keywords: English teaching, fun learning, speaking ability, video

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Authors: Wichian Sriprachan, Chutikarn Sriviboon

Abstract:

The objectives of this research were to study the management of local towns and to develop a better model of town management according to the Philosophy of Sufficiency Economy. This study utilized qualitative research, field research, as well as documentary research at the same time. A total of 10 local towns or Tambons of Supanburi province, Thailand were selected for an in-depth interview. The findings revealed that the model of local town management according to Philosophy of Sufficient Economy was in a level of “good” and the model of management has the five basic guidelines: 1) ability to manage budget information and keep it up-to-date, 2) ability to decision making according to democracy rules, 3) ability to use check and balance system, 4) ability to control, follow, and evaluation, and 5) ability to allow the general public to participate. In addition, the findings also revealed that the human resource management according to Philosophy of Sufficient Economy includes obeying laws, using proper knowledge, and having integrity in five areas: plan, recruit, select, train, and maintain human resources.

Keywords: management, local town (Tambon), principles of sufficiency economy, marketing management

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