Search results for: substrate integrated waveguide

Authors: Zone-Ching Lin, Hao-Yuan Jheng, Shih-Hung Ma

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The present paper proposes using atomic force microscopy (AFM) and the concept of specific down force energy (SDFE) to establish a method for fabricating and cutting the burr for Y shape nanochannel on silicon (Si) substrate. For fabricating Y shape nanochannel, it first makes the experimental cutting path planning for fabricating Y shape nanochannel until the fifth cutting layer. Using the constant down force by AFM and SDFE theory and following the experimental cutting path planning, the cutting depth and width of each pass of Y shape nanochannel can be predicted by simulation. The paper plans the path for cutting the burr at the edge of Y shape nanochannel. Then, it carries out cutting the burr along the Y nanochannel edge by using a smaller down force. The height of standing burr at the edge is required to be below the set value of 0.54 nm. The results of simulation and experiment of fabricating and cutting the burr for Y shape nanochannel is further compared.

Keywords: atomic force microscopy (AFM), nanochannel, specific down force energy (SDFE), Y shape, burr, silicon

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Authors: Mohammed Bello Sokoto, Adewumi Babatunde Adebayo, Ajit Singh

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The field experiment was conducted at the dry land Teaching and Research Farm of Usmanu Danfodiyo University, Sokoto, during the 2023 rainy season to determine the effects of organic, inorganic, soil conditioner and integrated use of soil conditioners (Agzyme) with organic (super gro) and inorganic fertilizers on the growth and yield of cowpea varieties. The research consisted of two cowpea varieties (SAMPEA-20-T and ex-GidanYunfa) and six combinations of organic and inorganic fertilizers and soil conditioners factorially combined and laid out in a Randomized Complete Block Design (RCBD) replicated three times. Data were collected on plant height, leaf area index, number of pods per plant, number of seeds per pod, days to 50% flowering, grain yield, and 100 seed weight. Results indicated that the 100% inorganic fertilizer had a significantly increased growth parameter such as plant height and number of leaves, while combined application of the organic fertilizer and soil conditioner resulted in a significant increase in yield parameters such as number of pods per plant, number of seeds per pod, 100 seed weight and grain yield. The study observed that the use of soil conditioner in combination with fertilizers supports sustainable cowpea production. Application of 50% recommended inorganic + 50% soil conditioner or 50% liquid organic + 50% soil conditioner was better in increasing the number of pods/plant, seeds/pod, 100 seed weight and grain yield. The ex-Gidan Yunfa cowpea variety generally performed better in most parameters measured, such as plant height, days to 50% flowering, number of pods per plant, number of seeds per pod, 100 seed weight and grain yield. Therefore, the combined application of 50% recommended inorganic + 50% soil conditioner or 50% liquid organic + 50% soil conditioner is effective for the sustainable production of cowpeas.

Keywords: integrated, fertilizers, growth, yield, cowpea, Sudan Savannah

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Authors: Soufiene Ilahi, Noureddine Yacoubi

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GaInAsSb grown on GaSb substrate is an interesting material employed as an active layer in vertical-cavity surface-emitting lasers (VCSELs) operating in mid-infrared emission. This material presents some advantages like highs optical absorption coefficient and good thermal conductivity, which is very desirable for VCSEL application. In this paper, we have investigated the effects of thermal annealing on optical properties and thermal conductivity of GaInAsSb/GaSb. The studies are carried out by means of the photo thermal deflection spectroscopy technique (PDS). In fact, optical absorption spectrum and thermal conductivity have been determined by a comparison between the experimental and theoretical phases of the PDS signal. We have found that thermal conductivity increased significantly to 13 W/m.K for GaInAsSb annealed during 60 min. In addition, we have found that bandgap energy is blue-shifted around 30 meV. The amplitudes signal of PDS reveals multiple reflections as a function of annealing time, which reflect the high crystalline quality of the layer.

Keywords: thermal conductivity, bandgap energy of GaInAsSb, GaInAsSb active layer, optical absorption

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Authors: T. Nouri, Y. H. A. Reguieg, A. Latigui, A. Ouaini

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Salinity is considered as the most important abiotic factor. It limits growth and productivity of plants and degrades agricultural soils and ecosystem in arid and semi arid area. The study was conducted on Vicia faba L.’Semilla violeta’. Sowing was realized in plastic pots containing sandy substrates of bentonite 0, 3, 5, 7, and 10% associated with abiotic stresses of salinity corresponding to doses of NaCl, MgCl2 and MgSO4 20, 40, and 60 mmol/l respectively. The purpose of this work is to study the combined effect of salinity and of bentonite on a plant commonly cultivated in Algeria the broad bean Vicia faba has through the chemical and hydrous parameter. The results show that the combined action of strong concentration salt (40 and 60 mmol/l) and of bentonite a reduction of the relative content water reveals, against an increase in the content of hydrous deficit and of sodium. The growth of broad bean is significant in the substrate amended to 5 % of bentonite.

Keywords: salinity, bentonite, Vicia faba L, sodium content, hydrous parameters

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Authors: Abbas Nasir, Xiong Zhang, Sohail Ahmad, Yiping Cui

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Non-polar a-plane AlGaN epilayers of high structural quality have been grown on r-sapphire substrate by using metalorganic chemical vapor deposition (MOCVD). A graded non-polar AlGaN buffer layer with variable aluminium concentration was used to improve the structural quality of the non-polar a-plane AlGaN epilayer. The characterisations were carried out by high-resolution X-ray diffraction (HR-XRD), atomic force microscopy (AFM) and Hall effect measurement. The XRD and AFM results demonstrate that the Al-composition-graded non-polar AlGaN buffer layer significantly improved the crystalline quality and the surface morphology of the top layer. A low root mean square roughness 1.52 nm is obtained from AFM, and relatively low background carrier concentration down to 3.9×  cm^-3 is obtained from Hall effect measurement.

Keywords: non-polar AlGaN epilayer, Al composition-graded AlGaN layer, root mean square, background carrier concentration

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Authors: Latef M. Ali, Farah A. Abed, Zheen L. Mohammed

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In this paper, the effect of the Barium fluoride (BaF2) layer on the absorption efficiency of GaAs/InAs nanowire solar cells was investigated using the finite difference time domain (FDTD) method. By inserting the BaF2 as antireflection with the dominant size of 10 nm to fill the space between the shells of wires on the Si (111) substrate. The absorption is significantly improved due to the strong reabsorption of light reflected at the shells and compared with the reference cells. The present simulation leads to a higher absorption efficiency (Qabs) and reaches a value of 97%, and the external quantum efficiencies (EQEs) above 92% are observed. The current density (Jsc) increases by 0.22 mA/cm2 and the open-circuit voltage (Voc) is enhanced by 0.11 mV. it explore the design and optimization of high-efficiency solar cells on low-reflective absorption efficiency of GaAs/InAs using simulation software tool. The changes in the core and shell diameters profoundly affects the generation and recombination process, thus affecting the conversion efficiency of solar cells.

Keywords: nanowire solar cells, absorption efficiency, photovoltaic, band structures, FDTD simulation

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Authors: Qingsheng Qi, Cuijuan Gao, Carol Sze Ki Lin

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Food waste can be defined as a by-product of food processing by industries and consumers, which has not been recycled or used for other purposes. Stringent waste regulations worldwide are pushing local companies and sectors towards higher sustainability standards. The development of novel strategies for food waste re-use is economically and environmentally sound, as it solves a waste management issue and represents an inexpensive nutrient source for biotechnological processes. For example, Yarrowia lipolytica is a yeast which can utilize hydrophobic substrates, such as fatty acids, lipids, and alkanes and simple carbon sources, such as glucose and glycerol, which can all be found in food waste. This broad substrate range makes Y. lipolytica a promising candidate for the degradation and valorisation of food waste, and for the production of organic acids, such as citric and α-ketoglutaric acids. Current research conducted in our group demonstrated that Y. lipolytica was shown to be able to produce succinic acid. In this talk, we will focus on the application of genetically modified yeast Y. lipolytica for fermentative succinic acid production with an aim to increase productivity and yield.

Keywords: food waste, succinic acid, Yarrowia lipolytica, bioplastic

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Authors: Rajesh P.P., Md. Tabish Noori, Makarand M. Ghangrekar

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Methanogenic substrate loss is reported to be a major bottleneck in microbial fuel cell which significantly reduces the power production capacity and coulombic efficiency (CE) of microbial fuel cell (MFC). Nitroethane is found to be a potent inhibitor of hydrogenotrophic methanogens in rumen fermentation process. Influence of nitroethane pre-treated sewage sludge inoculum on suppressing the methanogenic activity and enhancing the electrogenesis in MFC was evaluated. MFC inoculated with nitroethane pre-treated anodic inoculum demonstrated a maximum operating voltage of 541 mV, with coulombic efficiency and sustainable volumetric power density of 39.85 % and 14.63 W/m3 respectively. Linear sweep voltammetry indicated a higher electron discharge on the anode surface due to enhancement of electrogenic activity while suppressing methanogenic activity. A 63 % reduction in specific methanogenic activity was observed in anaerobic sludge pre-treated with nitroethane; emphasizing significance of this pretreatment for suppressing methanogenesis and its utility for enhancing electricity generation in MFC.

Keywords: coulombic efficiency, methanogenesis inhibition, microbial fuel cell, nitroethane

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Authors: Boukhiar Aissa, Halladj Fatima, Iguergaziz Nadia, Lamrani yasmina, Benamara Salem

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Determining the alcohol content in alcoholic fermentation bioprocess is of great importance. In fact, it is a key indicator for monitoring this bioprocess. Several methodologies (chemical, spectrophotometric, chromatographic) are used to the determination of this parameter. However, these techniques are very long and they require: rigorous preparations, sometimes dangerous chemical reagents and/or expensive equipment. In the present study, the date juice is used as the substrate of alcoholic fermentation. The extracted juice undergoes an alcoholic fermentation by Saccharomyces cerevisiae. The study of the possible use of refractometry as a sole means for the in situ control of alcoholic fermentation revealed a good correlation (R2=0.98) between initial and final °Brix: °Brixf=0.377×°Brixi. In addition, the relationship between Δ°Brix and alcoholic content of the final product (A,%) has been determined: Δ°Brix/A=1.1. The obtained results allowed us to establish iso-responses abacus, which can be used for the determination of alcohol and residual sugar content, with a mean relative error (MRE) of 5.35%.

Keywords: alcoholic fermentation, date juice, refractometry, residual sugar

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Authors: Kanouni Fares

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This paper describes application of X-doped AlN (X=Sc, Cr and Y) to wideband surface acoustic wave (SAW) resonators in 200–300 MHz range. First, it is shown theoretically that Cr doped AlN thin film has the highest piezoelectric strain constant, accompanied by a lowest mechanical softening compared to Sc doped AlScN and Y doped AlN thin films for transition metals concentrations ranging from 0 to 25%. Next, the impact of transition metals (Sc, Cr and Y) concentration have been carried out for the first time, in terms of surface wave velocity, electrode reflectivity, transduction coefficient and distributed finger capacitance. Finely, the insertion loss of two-port SAW resonator based on AlXN (X=Sc, Cr and Y) deposited on sapphire substrate is obtained using P-matrix model, and it is shown that AlCrN-SAW resonator exhibit lower insertion loss compared to those based on AlScN and AlYN for metal concentrations of 25%.This finding may position Cr doped AlN as a prime piezoelectric material for low loss SAW resonators whose performance can be tuned via Cr composition.

Keywords: P-Matrix, SAW-delay line, interdigital transducer, nitride aluminum, metals transition

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Authors: Sousan Arafeh

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Educational systems and schools worldwide are increasingly reliant on information and communication technology (ICT). Unfortunately, most educational leadership development programs do not offer formal curricular and/or field experiences that prepare students for managing ICT resources, personnel, and processes. The result is a steep learning curve for the leader and his/her staff and dissipated organizational energy that compromises desired outcomes. To address this gap in education leaders’ development, Arafeh’s Integrated Technology Leadership Model (AITLM) was created. It is a conceptual model and tool that educational leadership students can use to better understand the ICT ecology that exists within their schools. The AITL Model consists of six 'infrastructure types' where ICT activity takes place: technical infrastructure, communications infrastructure, core business infrastructure, context infrastructure, resources infrastructure, and human infrastructure. These six infrastructures are further divided into 16 key areas that need management attention. The AITL Model was created by critically analyzing existing technology/ICT leadership models and working to make something more authentic and comprehensive regarding school leaders’ purview and experience. The AITL Model then served as a tool when it was distributed to over 150 educational leadership students who were asked to review it and qualitatively share their reactions. Students said the model presented crucial areas of consideration that they had not been exposed to before and that the exercise of reviewing and discussing the AITL Model as a group was useful for identifying areas of growth that they could pursue in the leadership development program and in their professional settings. While development in all infrastructures and key areas was important for students’ understanding of ICT, they noted that they were least aware of the importance of the intangible area of the resources infrastructure. The AITL Model will be presented and session participants will have an opportunity to review and reflect on its impact and utility. Ultimately, the AITL Model is one that could have significant policy and practice implications. At the very least, it might help shape ICT content in educational leadership development programs through curricular and pedagogical updates.

Keywords: education leadership, information and communications technology, ICT, leadership capacity building, leadership development

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Authors: Hasen Keder Edris, Ryuji Matsunaga, Toshi Yamanaka

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The issue of climate change and its impact is a major contemporary global concern. Ethiopia is one of the countries experiencing adverse climate change impact including frequent extreme weather events that are exacerbating drought and water scarcity. Due to this reason, the government of Ethiopia develops a strategic document which focuses on the climate resilience green economy. One of the major components of the strategic framework is designed to improve community adaptation capacity and mitigation of drought. For effective implementation of the strategy, identification of regions relative vulnerability to drought is vital. There is a growing tendency of applying Geographic Information System (GIS) and Remote Sensing technologies for collecting information on duration and severity of drought by direct measure of the topography as well as an indirect measure of land cover. This study aims to show an application of remote sensing technology and GIS for developing drought vulnerability index by taking lowland of Ethiopia as a case study. In addition, it assesses integrated Information Communication Technology (ICT) potential of Ethiopia lowland and proposes integrated solution. Satellite data is used to detect the beginning of the drought. The severity of drought risk prone areas of livestock keeping pastoral is analyzed through normalized difference vegetation index (NDVI) and ten years rainfall data. The change from the existing and average SPOT NDVI and vegetation condition index is used to identify the onset of drought and potential risks. Secondary data is used to analyze geographical coverage of mobile and internet usage in the region. For decades, the government of Ethiopia introduced some technologies and approach to overcoming climate change related problems. However, lack of access to information and inadequate technical support for the pastoral area remains a major challenge. In conventional business as usual approach, the lowland pastorals continue facing a number of challenges. The result indicated that 80% of the region face frequent drought occurrence and out of this 60% of pastoral area faces high drought risk. On the other hand, the target area mobile phone and internet coverage is rapidly growing. One of identified ICT solution enabler technology is telecom center which covers 98% of the region. It was possible to identify the frequently affected area and potential drought risk using the NDVI remote-sensing data analyses. We also found that ICT can play an important role in mitigating climate change challenge. Hence, there is a need to strengthen implementation efforts of climate change adaptation through integrated Remote Sensing and web based information dissemination and mobile alert of extreme events.

Keywords: climate changes, ICT, pastoral, remote sensing

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Authors: Sarah Akhtar, Rizwan Mahmood

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A detailed study of homogeneous alignment of liquid crystal molecules on a glass substrate will be presented. Thin films of polyimide were coated on several glass substrates. Various methods were employed to prepare coated surfaces to achieve desired alignment; these include traditionally rubbing the surface with a felt cloth then exposing them perpendicular to the easy axis with incandescent light (IL), linearly polarized ultraviolet (LPUVR) and un-polarized ultraviolet (UPUVR) radiation. The quality of the alignment was tested by measuring the tilt angle in the temperature range between 30°C to 55°C. Regression analysis of the data using ‘SigmaPlot’ suggests a gradual increase in tilt angle (1.1°-1.8°) for the rubbed, 0.6° to 3.6° increase for the rubbed plus IL radiated and 1.6° to 4.6° for the rubbed plus UPUVL radiated samples, respectively. However to our surprise, we found tilt angle to be decreasing from 2.4° to 1.6° for the rubbed plus LPUVL radiated samples. We hope that these findings will be helpful in the fabrication of display panels and other electro-optic devices.

Keywords: homogeneous, liquid crystals, polyimide, tilt angle

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Authors: Ali Bahri Lubis

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The study of dioxygenase enzymatic mechanism on tryptophan oxidation has been a wide interest since the reaction is rate-limiting step of kynurenine pathway. In this research, observation of tryptophan oxidation through h-IDO enzyme along with synthesis of enzyme products was conducted in order to comprehend how the enzyme works on distinct substrates. UV-vis spectrophotometry, LC-MS, H-NMR and HSQC measurement were carried out to characterise enzyme product. It is found that while tryptophan was oxidised to form Nformylkynurenine (NFK) as a major product and hydroxypyrroloindole amine carboxylic acid (HPIC) in cis and trans confirmed in HSQC, N-methyl tryptophan substrate was converted to NFK and trans HPIC only. Other intriguing results showed that 5-hydroxy- tryptophan and Stryptophan was degraded to become NFK and epoxide cyclic respectively. The formation of NFK was considered through dioxygenation pathway, however HPIC was formed via monooxygenation. The epoxide cyclic—considered as intermediate compound in the mechanism— from S-tryptophan was not able to cleave the epoxide ring since bond energy of epoxide was probably much stronger. This validates the enzymatic mechanism where the intermediate compound in the enzymatic mechanism is epoxide cyclic.

Keywords: tryptophan oxidation, heme-dioxygenases, N-formylkynurenine, hydroxypyrrroloindoleamine, monooxidation

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Authors: Kristina Sutiene, Lina Dapkute

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The paper investigates the current demographic trends that exert the sustainability of pension systems in most EU regions. Several drivers usually compose the demographic challenge, coming from the structure and trends of population in the country. As the case of research, three main variables of demographic risk in Lithuania have been singled out and have been used in making up the analysis. Over the last two decades, the country has presented a peculiar demographic situation characterized by pessimistic fertility trends, negative net migration rate and rising life expectancy that make the significant changes in labor-age population. This study, therefore, sets out to assess the relative impact of these risk factors both individually and in aggregate, while assuming economic trends to evolve historically. The evidence is presented using data of pension funds that operate in Lithuania and are financed by defined-contribution plans. To achieve this goal, the discrete-time pension fund’s value model is developed that reflects main operational modalities: contribution income from current participants and new entrants, pension disbursement and administrative expenses; it also fluctuates based on returns from investment activity. Age-structured Leslie population dynamics model has been integrated into the main model to describe the dynamics of fertility, migration and mortality rates upon age. Validation has concluded that Leslie model adequately fits the current population trends in Lithuania. The elasticity of pension system is examined using Loimaranta efficiency as a measure for comparison of plausible long-term developments of demographic risks. With respect to the research question, it was found that demographic risks have different levels of influence on future value of aggregated pension funds: The fertility rates have the highest importance, while mortality rates give only a minor impact. Further studies regarding the role of trying out different economic scenarios in the integrated model would be worthwhile.

Keywords: asset liability modelling, Leslie model, pension funds, population dynamics

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Authors: Yong Xue, Daniel A. Menascé

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Automated and end-to-end network resource management and provisioning for virtual service networks in a multiple autonomous systems (a.k.a multi-AS) environment is a challenging and open problem. This paper proposes a novel, scalable and interoperable high-level architecture that incorporates a number of emerging enabling technologies including Software Defined Network (SDN), Network Function Virtualization (NFV), Service Oriented Architecture (SOA), and Autonomic Computing. The proposed architecture can be used to not only automate network resource management and provisioning for virtual service networks across multiple autonomous substrate networks, but also provide an adaptive capability for achieving optimal network resource management and maintaining network-level end-to-end network performance as well. The paper argues that this SDN and autonomic computing based architecture lays a solid foundation that can facilitate the development of the future Internet based on the pluralistic paradigm.

Keywords: virtual network, software defined network, virtual service network, adaptive resource management, SOA, multi-AS, inter-domain

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Authors: Christopher Restall

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field causing attraction between mixed charges of matter during charge exchanges with antimatter. This asymmetry is caused from none-trinary quark amount variation in matter and anti-matter during entropy progression. This document explains how a circularity critique exercise assessed scientific knowledge and develop a unified theory from the information collected. The circularity critique, creates greater intuition leaps than an individual would naturally, the information collected can be integrated and assessed thoroughly for correctness.

Keywords: unified theory of everything, gravity, quantum gravity, standard model

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Authors: M. Khalid Alamgir, Javed Ahsan Bhatti, M. Zafarullah Khan

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Thin film of amorphous carbon (DLC) was deposited on 316 steel using Nd: YAG laser having energy 300mJ. Pure graphite was used as a target. The vacuum in the deposition chamber was generated in the range of 10-6 mbar by turbo molecular pump. Ratio of sp3 to sp2 content shows amorphous nature of the film. This was confirmed by Raman spectra having two peaks around 1300 cm-1 i.e. D-band to 1700 cm-1 i.e. G-band. If sp3 bonding ratio is high, the films behave like diamond-like whereas, with high sp2, films are graphite-like. The ratio of sp3 and sp2 contents in the film depends upon the deposition method, hydrogen contents and system parameters. The structural study of the film was carried out by XRD. The hardness of the films as measured by Vickers hardness tester and was found to be 28 GPa. The EDX result shows the presence of carbon contents on the surface in high rate and optical microscopy result shows the smoothness of the film on substrate. The film possesses good adhesion and can be used to coat surgical instruments.

Keywords: DLC, thin film, Raman spectroscopy, XRD, EDX

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Authors: Glauco M. M. M. Lustosa, João Paulo C. Costa, Leinig Antônio Perazolli, Maria Aparecida Zaghete

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SnO2 has electrical conductivity due to the excess of electrons and structural defects, being its electrical behavior highly dependent on sintering temperature and chemical composition. The addition of metals modifiers into the crystalline structure can improve and controlling the behavior of some semiconductor oxides that can therefore develop different applications such as varistors (ceramic with non-ohmic behavior between current and voltage, i.e. conductive during normal operation and resistive during overvoltage). The polymeric precursor method, based on the complexation reaction between metal ion and policarboxylic acid and then polymerized with ethylene glycol, was used to obtain nanopowders ceramic. The metal immobilization reduces its segregation during the decomposition of the polyester resulting in a crystalline oxide with high chemical homogeneity. The preparation of films from ceramics nanoparticles using electrophoretic deposition method (EPD) brings prospects for a new generation of smaller size devices with easy integration technology. EPD allows to control time and current and therefore it can have control of the thickness, surface roughness and the film density, quickly and with low production costs. The sintering process is key to control size and grain boundary density of the film. In this step, there is the diffusion of metals that promote densification and control of intrinsic defects or change these defects which will form and modify the potential barrier in the grain boundary. The use of microwave oven for sintering is an advantageous process due to the fast and homogeneous heating rate, promoting the diffusion and densification without irregular grain growth. This research was done a comparative study of sintering temperature by use of zinc as modifier agent to verify the influence on sintering step aiming to promote densification and grain growth, which influences the potential barrier formation and then changed the electrical behavior. SnO2-nanoparticles were obtained with 1 %mol of ZnO + 0.05 %mol of Nb2O5 (SZN), deposited as film through EPD (voltage 2 kV, time of 10 min) on Si/Pt substrate. Sintering was made in a microwave oven at 800, 900 and 1000 °C. For complete coverage of the substrate by nanoparticles with low surface roughness and uniform thickness was added 0.02 g of solid iodine in alcoholic suspension SnO2 to increase particle surface charge. They were also used magneto in EPD system that improved the deposition rate forming a compact film. Using a scanning electron microscope of high resolution (SEM_FEG) it was observed nanoparticles with average size between 10-20 nm, after sintering the average size was 150 to 200 nm and thickness of 5 µm. Also, it was verified that the temperature at 1000 °C was the most efficient in sintering. The best sintering time was also recorded and determined as 40 minutes. After sintering, the films were recovered with Cr3+ ions layer by EPD, then the films were again thermally treated. The electrical characterizations (nonlinear coefficient of 11.4, voltage rupture of ~60 V and leakage current = 4.8x10−6 A), allow considering the new methodology suitable for prepare SnO2-based varistor applied for development of electrical protection devices for low voltage.

Keywords: chemical synthesis, electrophoretic deposition, microwave sintering, tin dioxide

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Authors: A. I. Ma’ali, R. B. Adeniyi, A. Y. Badeggi, U. Mohammed

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An error estimation of the integrated formulation of the Lanczos tau method for some class of ordinary differential equations was reported. This paper is concern with the generalization of tau approximants and their corresponding error estimates for some class of ordinary differential equations (ODEs) characterized by m + s =3 (i.e for m =1, s=2; m=2, s=1; and m=3, s=0) where m and s are the order of differential equations and number of overdetermination, respectively. The general result obtained were validated with some numerical examples.

Keywords: approximant, error estimate, tau method, overdetermination

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Authors: A. G. More

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Bioelectrochemical system (BES) is an alternative technology for chromium Cr (VI) removal from industrial wastewater to overcome the existing drawbacks of high chemical and energy consumption by conventional metal removal technologies. A well developed anaerobic sludge was developed in laboratory and used in the batch study of BES at different Cr (VI) concentrations (10, 20, 50, and 50 mg/L) with different COD concentrations (500, 1000, 1500 and 2000 mg/L). Sodium acetate was used as carbon source, whereas Cr (VI) contaminated synthetic wastewater was prepared and added to the cathode chamber. Initially, operating conditions for the BES experiments were optimized. During the study, optimum cathode pH of 2, whereas optimum HRT of 72 hr was obtained. During the study, cathode pH 2 ± 0.1 showed maximum chromium removal efficicency (CRE) of 88.36 ± 8.16% as compared to other pH (1-7) in the cathode chamber. Maximum CRE obtained was 85.93 ± 9.62% at 40°C within the temperature range of 25°C to 45°C. Conducting the BES experiments at optimized operating conditions, CRE of 90.2 %, 93.7 %, 83.75 % and 74.6 % were obtained at cathodic Cr concentration of 10, 20, 50, and 50 mg/L, respectively. BES is a sustainable, energy efficient technology which can be suitably used for metal removal from industrial wastewater.

Keywords: bioelectrochemical system, metal removal, microorganisms, pH and temperature, substrate

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Authors: Amir Reza Radmanesh, Sina Farajzadeh Khosroshahi, Hani Sadr

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The transient catalytic converter performance is governed by complex interactions between exhaust gas flow and the monolithic structure of the catalytic converter. Stringent emission regulations around the world necessitate the use of highly-efficient catalytic converters in vehicle exhaust systems. Computational fluid dynamics (CFD) is a powerful tool for calculating the flow field inside the catalytic converter. Radial velocity profiles, obtained by a commercial CFD code, present very good agreement with respective experimental results published in the literature. However the applicability of CFD for transient simulations is limited by the high CPU demands. In the present work, Geometric modeling ceramic monolith substrate is done with square shaped channel type of Catalytic converter and it is coated platinum and palladium. This example illustrates the effect of flow distribution on thermal response of a catalytic converter and different gas flow velocities, during the critical phase of catalytic converter warm up.

Keywords: catalytic converter, computational fluid dynamic, porous media, velocity distribution

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Authors: Anuradha Maharaj, Adrian Cashman

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The cross-cutting nature of water as a resource translates into the need for a better understanding of its movement, storage and loss at all points in the hydro-socioeconomic cycle. An integrated approach to addressing the issue of sustainability means quantitatively understanding: the linkages within this cycle, the role of water managers in resource allocation, and the critical factors influencing its scarcity. The Water Evaluation and Planning Tool (WEAP) is an integrative model that combines the catchment-scale hydrologic processes with a water management model, driven by environmental requirements and socioeconomic demands. The concept of demand priorities is included to represent the areas of greatest use within a given catchment. Located on Barbados’ West Coast, Speightstown and the surrounding areas encompass a well-developed tourist, residential and agricultural area. The main water resource for this area, and the rest of the island, is that of groundwater. The availability of groundwater in Barbados may be adversely affected by the projected changes in climate, such as reduced wet season rainfall. Economic development and changing sector priorities together with climate related changes have the potential to affect water resource abundance and by extension the allocation of resources for example in the Speightstown area. In order to investigate the potential impacts on the Speightstown area specifically, a WEAP Model of the study area was developed to estimate the present available water (baseline reference scenario 2000-2010). From this baseline scenario, it is envisioned that an exploration into projected changes in availability in the near term (2035-2045) and medium/long term (2065-2075) time frames will be undertaken. The generated estimations can assist water managers to better evaluate the status of and identify trends in water use and formulate adaptation measures to offset future deficits.

Keywords: water evaluation and planning system (WEAP), water availability, demand and supply, water allocation

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Authors: Jaibir Sharma, Lee JaeWung, Merugu Srinivas, Navab Singh

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This paper presents thermal annealing dewetting technique for the preparation of porous metal membrane for thin film encapsulation application. Thermal annealing dewetting experimental results reveal that pore size in porous metal membrane depend upon i.e. 1. The substrate on which metal is deposited for formation of porous metal cap membrane, 2. Melting point of metal used for porous metal cap layer membrane formation, 3. Thickness of metal used for cap layer, 4. Temperature used for porous metal membrane formation. Silver (Ag) was used as a metal for preparation of porous metal membrane by annealing the film at different temperature. Pores in porous silver film were analyzed using Scanning Electron Microscope (SEM). In order to check the usefulness of porous metal film for thin film encapsulation application, the porous silver film prepared on amorphous silicon (a-Si) was release using XeF2. Finally, guide line and structures are suggested to use this porous membrane for thin film encapsulation (TFE) application.

Keywords: dewetting, themal annealing, metal, melting point, porous

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Authors: Debarun Dhar Purkayastha, Talinungsang

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SnO₂-TiO₂ nanocomposite thin films were prepared by the sol-gel method on borosilicate glass substrate. The films were annealed at a temperature of 300ᵒC, 400ᵒC, and 500ᵒC respectively for 2h in the air. The films obtained were further modified with stearic acid in order to decrease the surface energy. The X-ray diffraction patterns for the SnO₂-TiO₂ thin films after annealing at different temperatures can be indexed to the mixture of TiO₂ (rutile and anatase) and SnO₂ (tetragonal) phases. The average crystallite size calculated from Scherrer’s formula is found to be 6 nm. The SnO₂-TiO₂ thin films were hydrophilic which on modification with stearic acid exhibit superhydrophobic behavior. The increase in hydrophobicity of SnO₂ film with stearic acid modification is attributed to the change in surface energy of the film. The films exhibit superhydrophilic behavior under UV irradiation for 1h. Thus, it is observed that stearic acid modified surfaces are superhydrophobic but convert into superhydrophilic on being subjected to UV irradiation. SnO₂-TiO₂ thin films have potential for self-cleaning applications because of photoinduced hydrophilicity under UV irradiation.

Keywords: nanocomposite, self-cleaning, superhydrophobic, surface energy

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Authors: T. M. Aminu, A. Salisu, B. Abdu, H. U. Alhassan, T. H. Dharma

Abstract:

Thin films of CuAlO2 were deposited on clean glass substrate using the chemical solution deposition (sol-gel) method of deposition with CuCl and AlCl3 taken as the starting materials. CuCl was dissolved in HCl while AlCl₃ in distilled water, pH value of the mixture was controlled by addition of NaOH. The samples were annealed at different temperatures in order to determine the effect of annealing temperatures on the morphological and optical properties of the deposited CuAlO₂ thin film. The surface morphology reveals an improved crystalline as annealing temperature increases. The results of the UV-vis and FT-IR spectrophotometry indicate that the absorbance for all the samples decreases sharply from a common value of about 89% at about 329 nm to a range of values of 56.2%-35.2% and the absorption / extinction coefficients of the films decrease with increase in annealing temperature from 1.58 x 10⁻⁶ to1.08 x 10⁻⁶ at about 1.14eV in the infrared region to about 1.93 x 10⁻⁶ to 1.29 x 10⁻⁶ at about 3.62eV in the visible region, the transmittance, reflectance and band gaps vary directly with annealing temperature, the deposited films were found to be suitable in optoelectronic applications.

Keywords: copper aluminium-oxide (CuAlO2), absorbance, transmittance, reflectance, band gaps

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Authors: Heesuk Seo, Yongtae Kim

Abstract:

Online learning started in the 1990s, the spread of the Internet has been through the era of e-learning paradigm of online education in the era of smart learning change. Reflecting the different nature of the mobile to anywhere anytime, anywhere was also allows the form of learning, it was also available through the learning content and interaction. We are developing a cloud system, 'TLINKS CLOUD' that allows you to configure the environment of the smart learning without the need for additional infrastructure. Using the big-data analysis for e-learning contents, we provide an integrated solution for e-learning tailored to individual study.

Keywords: authority tool, big data analysis, e-learning, HTML5

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Authors: Ashan Wijekoon, Abi Beane, Subashini Jayawardana

Abstract:

Background: Civil war in Sri Lanka ended a decade ago, leaving thousands of army veterans permanently disabled following lower-limb amputations. Quantifying long-term functional health and psychological wellbeing will inform the development of tailored home-based rehabilitation intervention. Objectives: To assess the long-term health and quality of life of Sri Lankan soldiers with traumatic lower-limb amputation.Methods and Materials: A comparative cross-sectional study was conducted in five districts of Sri Lanka. Using stratified random sample technique, two groups of 85 participants were selected; group 1, community re-integrated male army veterans with unilateral lower-limb amputation, and group 2, age and sex matched normal healthy individuals. Long-term health and quality of life (QoL) outcomes were assessed and compared between the two groups using self-administered Short-Form Health Survey-36 questionnaire (SF-36) previously validated for use in Sri Lanka. Results: Group 1 were active prosthetic users who had undergone amputation > ten years ago (Mean±SD: 21.7±5.9). The most prevalent comorbidities for group 1 and 2 were hypertension and diabetes (22.4% and 30.6% and 9.4% and 9.8%, respectively). In group 1, injury-associated long-term health outcomes included knee osteoarthritis (18.8%), knee pain (20.0%), and back pain (69.4%). Scores of physical health and psychological wellbeing were 53.1 (IQR 64.4- 43.8) and 63.5 (IQR 73.3- 51.4) for each group, respectively. Scores revealed the highest QoL related to social functioning (75 (IQR 87.5- 62.5)) and the poorest aspects of QoL related to general health (40 (IQR 50- 35)). Prevalence of comorbidities was significantly higher, and QoL outcomes were significantly lower among soldiers compared to normal healthy individuals (p<0.05).Conclusion: Higher prevalence of comorbidities, poor physical health, and lower QoL outcomes were more prevalent in soldiers with lower-limb amputation when compared to healthy counterparts.

Keywords: community-based, disability, health outcomes, quality of life, soldiers

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Authors: Victor Alves Barros Galvão, Israel Da Silveira Rego, Antonio Carlos Oliveira, Paulo Gilberto De Paula Toro

Abstract:

The Brazilian hypersonic aerospace vehicle 14-X B, VHA 14-X B, is a vehicle integrated with the hypersonic airbreathing propulsion system based on supersonic combustion (scramjet), developing in Aerothermodynamics and hypersonic Prof. Henry T. Nagamatsu Laboratory, to conduct demonstration in atmospheric flight at the speed corresponding to Mach number 7 at an altitude of 30km. In the experimental procedure the hypersonic shock tunnel T3 was used, installed in that laboratory. This device simulates the flow over a model is fixed in the test section and can also simulate different atmospheric conditions. The scramjet technology offers substantial advantages to improve aerospace vehicle performance which flies at a hypersonic speed through the Earth's atmosphere by reducing fuel consumption on board. Basically, the scramjet is an aspirated aircraft engine fully integrated that uses oblique/conic shock waves generated during hypersonic flight, to promote the deceleration and compression of atmospheric air in scramjet inlet. During the hypersonic flight, the vehicle VHA 14-X will suffer atmospheric influences, promoting changes in the vehicle's angles of attack (angle that the mean line of vehicle makes with respect to the direction of the flow). Based on this information, a study is conducted to analyze the influences of changes in the vehicle's angle of attack during the atmospheric flight. Analytical theoretical analysis, simulation computational fluid dynamics and experimental investigation are the methodologies used to design a technological demonstrator prior to the flight in the atmosphere. This paper considers analysis of the thermodynamic properties (pressure, temperature, density, sound velocity) in lower surface of the VHA 14-X B. Also, it considers air as an ideal gas and chemical equilibrium, with and without boundary layer, considering changes in the vehicle's angle of attack (positive and negative in relation to the flow) and bi-dimensional expansion wave theory at the expansion section (Theory of Prandtl-Meyer).

Keywords: angle of attack, experimental hypersonic, hypersonic airbreathing propulsion, Scramjet

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Authors: Riki H. Patel, Arpan Desai, Trushit Upadhyaya, Shobhit K. Patel

Abstract:

The micro strip antennas area has seen some inventive work in recent years and is now one of the most dynamic fields of antenna theory. A novel and simple printed wideband monopole antenna is presented. Printed on a single dielectric substrate and easily fed by using a 50 ohm microstip line, low-profile antenna structure with two parallel S-shaped meandered line of same size. In this research, S–form micro strip patch antenna is designed from measuring the prototypes of the proposed antenna one available bands with 10db return loss bandwidths of about GPS application (GPS L2 1490 MHz) and covering the 1400 to 1580 MHz frequency band at 1.5 GHz The simulated results for main parameters such as return loss, impedance bandwidth, radiation patterns and gains are also discussed herein. The modeling study shows that such antennas, in simplicity design and supply, and can satisfy GPS application. Two parallel slots are incorporated to disturb the surface flow path, introducing local inductive effect. This antenna is fed by a coaxial feeding tube.

Keywords: bandwidth, electrically small antenna, microstrip, patch antenna, GPS

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