Search results for: Selective Laser Melting (SLM)

Authors: Nguyen Thu Huong, Nguyen Quang Bau

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The Hall Coefficient (HC) and the Magnetoresistance (MR) have been studied in two-dimensional systems. The HC and the MR in Rectangular Quantum Wire (RQW) subjected to a crossed DC electric field and magnetic field in the presence of a Strong Electromagnetic Wave (EMW) characterized by electric field are studied in this work. Using the quantum kinetic equation for electrons interacting with optical phonons, we obtain the analytic expressions for the HC and the MR with a dependence on magnetic field, EMW frequency, temperatures of systems and the length characteristic parameters of RQW. These expressions are different from those obtained for bulk semiconductors and cylindrical quantum wires. The analytical results are applied to GaAs/GaAs/Al. For this material, MR depends on the ratio of the EMW frequency to the cyclotron frequency. Indeed, MR reaches a minimum at the ratio 5/4, and when this ratio increases, it tends towards a saturation value. The HC can take negative or positive values. Each curve has one maximum and one minimum. When magnetic field increases, the HC is negative, achieves a minimum value and then increases suddenly to a maximum with a positive value. This phenomenon differs from the one observed in cylindrical quantum wire, which does not have maximum and minimum values.

Keywords: hall coefficient, rectangular quantum wires, electron-optical phonon interaction, quantum kinetic equation

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Authors: Andreea Campu, Ilinica Muresan, Simona Cainap, Simion Astilean, Monica Focsan

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Acute myocardial infarction (AMI) is the most severe cardiovascular disease, which has threatened human lives for decades, thus a continuous interest is directed towards the detection of cardiac biomarkers such as cardiac troponin I (cTnI) in order to predict risk and, implicitly, fulfill the early diagnosis requirements in AMI settings. Microfluidics is a major technology involved in the development of efficient sensing devices with real-time fast responses and on-site applicability. Microfluidic devices have gathered a lot of attention recently due to their advantageous features such as high sensitivity and specificity, miniaturization and portability, ease-of-use, low-cost, facile fabrication, and reduced sample manipulation. The integration of gold nanoparticles into the structure of microfluidic sensors has led to the development of highly effective detection systems, considering the unique properties of the metallic nanostructures, specifically the Localized Surface Plasmon Resonance (LSPR), which makes them highly sensitive to their microenvironment. In this scientific context, herein, we propose the implementation of a novel detection device, which successfully combines the efficiency of gold bipyramids (AuBPs) as signal transducers and thermal generators with the sample-driven advantages of the microfluidic channels into a miniaturized, portable, low-cost, specific, and sensitive test for the dual LSPR-thermographic cTnI detection. Specifically, AuBPs with longitudinal LSPR response at 830 nm were chemically synthesized using the seed-mediated growth approach and characterized in terms of optical and morphological properties. Further, the colloidal AuBPs were deposited onto pre-treated silanized glass substrates thus, a uniform nanoparticle coverage of the substrate was obtained and confirmed by extinction measurements showing a 43 nm blue-shift of the LSPR response as a consequence of the refractive index change. The as-obtained plasmonic substrate was then integrated into a microfluidic “Y”-shaped polydimethylsiloxane (PDMS) channel, fabricated using a Laser Cutter system. Both plasmonic and microfluidic elements were plasma treated in order to achieve a permanent bond. The as-developed microfluidic plasmonic chip was further coupled to an automated syringe pump system. The proposed biosensing protocol implicates the successive injection inside the microfluidic channel as follows: p-aminothiophenol and glutaraldehyde, to achieve a covalent bond between the metallic surface and cTnI antibody, anti-cTnI, as a recognition element, and target cTnI biomarker. The successful functionalization and capture of cTnI was monitored by LSPR detection thus, after each step, a red-shift of the optical response was recorded. Furthermore, as an innovative detection technique, thermal determinations were made after each injection by exposing the microfluidic plasmonic chip to 785 nm laser excitation, considering that the AuBPs exhibit high light-to-heat conversion performances. By the analysis of the thermographic images, thermal curves were obtained, showing a decrease in the thermal efficiency after the anti-cTnI-cTnI reaction was realized. Thus, we developed a microfluidic plasmonic chip able to operate as both LSPR and thermal sensor for the detection of the cardiac troponin I biomarker, leading thus to the progress of diagnostic devices.

Keywords: gold nanobipyramids, microfluidic device, localized surface plasmon resonance detection, thermographic detection

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Authors: Barbara Kilosanidze, George Kakauridze, Levan Nadareishvili, Yuri Mshvenieradze

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A new method for determining the distribution of birefringence and linear dichroism in optical polymer materials is presented. The method is based on the use of polarization-holographic diffraction grating that forms an orthogonal circular basis in the process of diffraction of probing laser beam on the grating. The intensities ratio of the orders of diffraction on this grating enables the value of birefringence and linear dichroism in the sample to be determined. The distribution of birefringence in the sample is determined by scanning with a circularly polarized beam with a wavelength far from the absorption band of the material. If the scanning is carried out by probing beam with the wavelength near to a maximum of the absorption band of the chromophore then the distribution of linear dichroism can be determined. An appropriate theoretical model of this method is presented. A laboratory setup was created for the proposed method. An optical scheme of the laboratory setup is presented. The results of measurement in polymer films with two-dimensional gradient distribution of birefringence and linear dichroism are discussed.

Keywords: birefringence, linear dichroism, graded oriented polymers, optical polymers, optical anisotropy, polarization-holographic grating

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Authors: Sanaa Bardaweel

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Inorganic polyphosphate (poly P) is present in all living forms tested to date, from each of the three kingdoms of life. Studied mainly in prokaryotes, poly P and its associated enzymes are vital in diverse basic metabolism, in at least some structural functions and, notably, in stress responses. These plentiful and unrelated roles for poly P are probably the consequence of its presence in life-forms early in evolution. The genomes of many bacterial species, including pathogens, encode a homologue of a major poly P synthetic enzyme, poly P kinase 1 (PPK1). Genetic deletion of ppk1 results in reduced poly P levels and loss of pathogens virulence towards protozoa and animals. Thus far, no PPK1 homologue has been identified in higher-order eukaryotes and, therefore, PPK1 represents a novel target for chemotherapy. The idea of the current study is to purify the PPK1 from Escherichia coli to homogeneity in order to study the effect of active site point mutations on PPK1 catalysis via the application of site-directed mutagenesis strategy. The knowledge obtained about the active site of PPK1 will be utilized to characterize the catalytic and kinetic mechanism of PPK1 with model substrates. Comprehensive understanding of the enzyme kinetic mechanism and catalysis will be used to design and screen a library of synthetic compounds for potential discovery of selective PPK1-inhibitors.

Keywords: antimicobial, Escherichia coli, inorganic polyphosphate, PPK1-inhibitors

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Authors: Li Mengmeng, Kang Jian

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With the rapid development of the city, the noise pollution becomes more and more serious. Noise has seriously affected people's normal life, study and work. In addition, noise has seriously affected the city's ecological environment and the migration of birds. Therefore, it is urgent to control the noise. As one of natural noise-reducing materials, plants have been paid more and more attention. In urban landscape design, it is very important to choose plant species with good noise reduction effect to the sustainable development of urban ecology. The aim of this paper is to find out the characteristics of the plant with good noise reduction effect and apply it in urban landscape design. This study investigated the vibration of leaves of six plant species in a sound field using a Keyence (IG-1000/CCD) Laser Micrometer. The results of the experiments showed that the vibration speed of plant leaves increased obviously after being stimulated by sound source, about 5-10 times. In addition, when driven by the same sound, the speed of all leaves varied with the difference of leaf thickness, leaf size and leaf mass. The speed of all leaves would increase with the increase of leaf size and leaf mass, while those would decrease with the increase of leaf thickness.

Keywords: landscape design, leaf vibration , noise attenuation, plants configuration

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Authors: M. Lizzy Madiwani, Ignatious Ncube, Evelyn Madoroba

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This study was designed to determine the distribution of pathogenic bacteria in household raised chickens and study their virulence and antibiotic profiles. For this purpose, 40 chickens were purchased from families in the Capricorn district and sacrificed for sampling. Tissues were cultured on different bacteriological media followed by biotyping using Matrix-assisted Laser Desorption Ionization-time of Flight (MALDI-TOF). Disk diffusion test was performed to determine the antibiotic susceptibility profiles of these bacteria. Out of a total of 160 tissue samples evaluated, E. coli and Salmonella were detected in these tissues. Furthermore, determination of the pathogenic E. coli and Salmonella strains at species level using primer sets that target selected genes of interest in the polymerase chain reaction (PCR) assay was employed. The invA gene, a confirmatory gene of Salmonella was detected in all the Salmonella isolates. The study revealed that there is a high distribution of Salmonella and pathogenic E. coli in these chickens. Therefore, further studies on identification at the species level are highly recommended to provide management and sanitation practices to lower this prevalence. The antimicrobial susceptibly data generated from this study can be a valuable reference to veterinarians for treating bacterial diseases in poultry.

Keywords: antimicrobial, Escherichia coli, pathogens, Salmonella

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Authors: Saima Akbar, Tahseen Ullah Khan

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The analysis of the climate change impact on flood frequency represents an important issue for water resource management and flood risk mitigation. This research was conducted to address the effects of climate change on flood incidents of Pakistan and find out gaps in existing policies to reducing the environmental aspects on floods and effects of global warming. The main objective of this research was to critically analyses the National Climate Change Policy (NCCP), National Disaster Management Authority (NDMA), Federal Flood Commission (FFC) and Vision 2025, as an effective policy document which is not only hitting the target of a climate resilient Pakistan but provides room for efficient and flexible policy implementation. The methodology integrates projected changes in monsoon patterns (since last 20 years and overall change in rainfall pattern since 1901 to 2015 from Pakistan Metrological Department), glacier melting, decreasing dam capacity and lacks in existing policies by using SWOT (Strength, Weakness, Opportunities, Threats) model in order to explore the relative impacts of global warming on the system performance. Results indicate the impacts of climate change are significant, but probably not large enough to justify a major effort for adapting the physical infrastructure to expected climatic conditions in Vision 2025 which is our shared destination to progress, ultimate aspiration to see Pakistan among the ten largest economies of the world by 2047– the centennial year of our independence. The conclusion of this research was to adapt sustainable measures to reduce flood impacts and make policies as neighboring countries are adapting for their sustainability.

Keywords: climatic factors, monsoon, Pakistan, sustainability

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Authors: Valarmathi Subramaniam

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Ever since the first Indian feature film was produced and released by Shri Dada Saheb Phalke in the year 1931, the Indian Film Industry has grown leaps and bounds. The Indian Film Industry stands as the largest film industry in the world, and it produces more than a thousand films every year with investments and revenues worth several billion rupees. As per the official report published by UNESCO in the year 2017 on their website, it states that in the year 2015, India has produced one thousand nine hundred and seven feature films using digital technology. Not only is the cinema adapted to digital technologies, but the digital technologies also opened up avenues for talents to enter the cinema industry. This paper explores such talents who have emerged in the film industry without any background, neither academic nor from their family background, but holding digital media as their weapon. The research involves two variants of filmmaking technology – Celluloid and Digital. The study used a selective sampling of films that were released from the year 2020-to 2022. The sample has been organized, resulting in popular and fresh talents in the editing phase of filmmaking. There were 48 editors, of which 12 editors were not popular and 6 of them were fresh into the film without any background. Interview methods were used to collect data on what helped them to get into the industry straight. The study found that the digital medium and the digital technology enabled them to get into the film industry.

Keywords: digital media, digital in cinema, digital era talents, emerging new talents

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Authors: Makito Sakai, Takahiro Kiwata, Takumi Awa, Hiroshi Teramoto, Takaaki Kono, Kuniaki Toyoda

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Using experimental and numerical results, this paper describes the effects of tabs on the flow characteristics of a plane jet at comparatively low Reynolds numbers while focusing on the velocity field and the vortical structure. The flow visualization and velocity measurements were respectively carried out using laser Doppler velocimetry (LDV) and particle image velocimetry (PIV). In addition, three-dimensional (3D) plane jet numerical simulations were performed using ANSYS Fluent, a commercially available computational fluid dynamics (CFD) software application. We found that the spreads of jets perturbed by large delta tabs and round tabs were larger than those produced by the other tabs tested. Additionally, it was determined that a plane jet with square tabs had the smallest jet spread downstream, and the jet’s centerline velocity was larger than those of jets perturbed by the other tabs tested. It was also observed that the spanwise vortical structure of a plane jet with tabs disappeared completely. Good agreement was found between the experimental and numerical simulation velocity profiles in the area near the nozzle exit when the laminar flow model was used. However, we also found that large eddy simulation (LES) is better at predicting the developing flow field of a plane jet than the laminar and the standard k-ε turbulent models.

Keywords: plane jet, flow control, tab, flow measurement, numerical simulation

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Authors: Mohammed Idaan Hassan Al-Majidi

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An analysis of twenty one assorted brands of vegetable oils in Babylon Iraq, reveals varying levels of cholesterol content. Cholesterol was found to be present in most of the oil brands sampled using three standard methods. Cholesterol was detected in seventeen of the vegetable oil brands with concentration of less than 1 mg/ml while seven of the oil brands had cholesterol concentrations ranging between 1-4 mg/ml. Low iodine values were obtained in four of the vegetable oil brands and three of them had high acid values. High performance liquid chromatography (HPLC) confirmed the presence of cholesterol at varying concentrations in all the oil brands and gave the lowest detectable cholesterol values in all the oil brands. The Laser brand made from rapeseed had the highest cholesterol concentration of 3.2 mg/ml while Grand brand made from groundnuts had the least concentration (0.12 mg/ml) of cholesterol using HPLC analysis. Leibermann-Burchard method showed that Gino brand from palm kernel had the least concentration of cholesterol (3.86 mg/ml ±0.032) and the highest concentration of 3.996 mg/ml ±0.0404 was obtained in Sesame seed oil brand. This report is important in view of health implications of cholesterol in our diets. Consequently, we have been able to show that there is no cholesterol free oil in the market as shown on the vegetable oil brand labels. Therefore, companies producing and marketing vegetable oils are enjoined to desist from misleading the public by labeling their products as “cholesterol free”. They should indicate the amount of cholesterol present in the vegetable oil, no matter how small the quantity may be.

Keywords: vegetable oils, heart diseases, leibermann-burchard, cholesterol

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Authors: Anna Jastrzebska, K. S. Suresh, T. Kitashima, Y. Yamabe-Mitarai, Z. Pakiela

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Near α titanium alloys are important materials for aerospace applications, especially in high temperature applications such as jet engine. Mechanical properties of Ti alloys strongly depends on their processing route, then it is very important to understand micro-structure change by different processing. In our previous study, Nb was found to improve oxidation resistance of Ti alloys. In this study, micro-structure evolution of Ti-6Al-4Nb (wt %) alloy was investigated after plain strain compression test in hot working temperatures in the α and β phase region. High-resolution EBSD was successfully used for precise phase and texture characterization of this alloy. 1.1 kg of Ti-6Al-4Nb ingot was prepared using cold crucible levitation melting. The ingot was subsequently homogenized in 1050 deg.C for 1h followed by cooling in the air. Plate like specimens measuring 10×20×50 mm3 were cut from an ingot by electrical discharge machining (EDM). The plain strain compression test using an anvil with 10 x 35 mm in size was performed with 3 different strain rates: 0.1s-1, 1s-1and 10s-1 in 700 deg.C and 1050 deg.C to obtain 75% of deformation. The micro-structure was investigated by scanning electron microscopy (SEM) equipped with electron backscatter diffraction (EBSD) detector. The α/β phase ratio and phase morphology as well as the crystallographic texture, subgrain size, misorientation angles and misorientation gradients corresponding to each phase were determined over the middle and the edge of sample areas. The deformation mechanism in each working temperature was discussed. The evolution of texture changes with strain rate was investigated. The micro-structure obtained by plain strain compression test was heterogeneous with a wide range of grain sizes. This is because deformation and dynamic recrystallization occurred during deformation at temperature in the α and β phase. It was strongly influenced by strain rate.

Keywords: EBSD, plain strain compression test, Ti alloys

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Authors: Elitsa N. Kolentsova, Dimitar Y. Dimitrov, Petya Cv. Petrova, Georgi V. Avdeev, Diana D. Nihtianova, Krasimir I. Ivanov, Tatyana T. Tabakova

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Recently, copper and manganese-containing systems are recognized as active and selective catalysts in many oxidation reactions. The main idea of this study is to obtain more information about γ-Al₂O₃ supported Cu-La catalysts and to evaluate their activity to simultaneous oxidation of CO, CH₃OH and dimethyl ether (DME). The catalysts were synthesized by impregnation of support with a mixed aqueous solution of nitrates of copper, manganese and lanthanum under different conditions. XRD, HRTEM/EDS, TPR and thermal analysis were performed to investigate catalysts’ bulk and surface properties. The texture characteristics were determined by Quantachrome Instruments NOVA 1200e specific surface area and pore analyzer. The catalytic measurements of single compounds oxidation were carried out on continuous flow equipment with a four-channel isothermal stainless steel reactor in a wide temperature range. On the basis of XRD analysis and HRTEM/EDS, it was concluded that the active component of the mixed Cu-Mn-La/γ–alumina catalysts strongly depends on the Cu/Mn molar ratio and consisted of at least four compounds – CuO, La₂O₃, MnO₂ and Cu_1.5Mn_1.5O₄. A homogeneous distribution of the active component on the carrier surface was found. The chemical composition strongly influenced catalytic properties. This influence was quite variable with regards to the different processes.

Keywords: Cu-Mn-La oxide catalysts, carbon oxide, VOCs, deep oxidation

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Authors: Bouaziz Amira, Zaatout Nawel

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Background: Antimicrobial resistance is an urgent global health challenge in human and veterinary medicine, where migratory birds play a major role in the dissemination of multi-drug-resistant bacteria. The aim of this study was to screen for the presence of carbapenemase-producing Gram-negative bacteria (GNB) in the little egret (Egrettagarzetta) migratory bird stools in Algeria. Materials/Methods: In January 2014, 12 feacal samples were collected in Garaet El-Tarf, Oum El-Bouaghi city, Algeria. Samples were subjected to selective isolation of carbapenem-resistant GNB. Representative colonies were identified using the VITEK system. The obtained isolates were subjected to antibiotic susceptibility testing using the disc-diffusion method as well as carbapenemase production was verified by the modified Carba NP test. Results: In total, ten E. coli were obtained and were resistant to amoxicillin/clavulanic acid (100%), ertapenem (70%), cefoxitin (60%) cefotaxime (20%), cefepime (20%), ciprofloxacin (20%) and aztreonam (10%). The phenotypic detection results revealed that six out of the obtained strains were positive for the modified Carba NP test. Conclusion: The present study suggests that the little egret (Egretta garzetta) could be considered a reservoir of carbapenem-resistant Gram-negative bacteria.

Keywords: antimicrobial resistance, E. coli, Egretta garzetta, carbapenem resistance, dissemination

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Authors: Wei-Na Li, Mei-Lan Piao, Nam Kim

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We proposed a novel computer-generated hologram (CGH) achieved scheme, wherein the CGH is generated from a point cloud which is transformed by a mapping relationship of a series of elemental images captured from a real three-dimensional (3D) object by using a lens array. This scheme is composed of three procedures: mapping from elemental images to point cloud, hologram generation, and hologram display. A mapping method is figured out to achieve a virtual volume date (point cloud) from a series of elemental images. This mapping method consists of two steps. Firstly, the coordinate (x, y) pairs and its appearing number are calculated from the series of sub-images, which are generated from the elemental images. Secondly, a series of corresponding coordinates (x, y, z) are calculated from the elemental images. Then a hologram is generated from the volume data that is calculated by the previous two steps. Eventually, a spatial light modulator (SLM) and a green laser beam are utilized to display this hologram and reconstruct the original 3D object. In this paper, in order to show a more auto stereoscopic display of a real 3D object, we successfully obtained the actual depth data of every discrete point of the real 3D object, and overcame the inherent drawbacks of the depth camera by obtaining point cloud from the elemental images.

Keywords: elemental image, point cloud, computer-generated hologram (CGH), autostereoscopic display

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Authors: Mohammad Ali Karimi, Hossein Tavallali, Abdolhamid Hatefi-Mehrjardi

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In this study, an electrochemical sensor based on gold nanoparticles (AuNPs) functionalized improved graphene (AuNPs-IGE) was fabricated for selective determination of L-dopa in the presence of ascorbic acid by a novel self-assembly method. The AuNP IGE modified carbon paste electrode (AuNPs-IGE/CPE) utilized for investigation of the electrochemical behavior of L-dopa in phosphate buffer solution. Compared to bare CPE, AuNPs-IGE/CPE shows novel properties towards the electrochemical redox of levodopa (L-dopa) in phosphate buffer solution at pH 4.0. The oxidation potential of L-dopa shows a significant decrease at the AuNPs-IGE/CPE. The oxidation current of L-dopa is higher than that of the unmodified CPE. AuNPs-IG/CPE shows excellent electrocatalytic activity for the oxidation of ascorbic acid (AA). Using differential pulse voltammetry (DPV) method, the oxidation current is well linear with L-dopa concentration in the range of 0.4–50 µmol L-1, with a detection limit of about 1.41 nmol L-1 (S/N = 3). Therefore, it was applied to measure L-dopa from real samples that recoveries are 94.6-106.2%. The proposed electrode can also effectively avoid the interference of ascorbic acid, making the proposed sensor suitable for the accurate determination of L-dopa in both pharmaceutical preparations and human body fluids.

Keywords: gold nanoparticles, improved graphene, L-dopa, self-assembly

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Authors: Moussa I. Mohamed, Turki, K. A. Al-Faraj, Abdullah A. Al-Arfaj, Ashgan M. Hessain

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The objective of the present study is to detect the incidences of Salmonella enterica from different poultry farms located in Egypt on molecular basis. During the summer of 2012, a total of 1800 cloacal swabs were collected from poultry farms located I Cairo, Egypt to be subjected for isolation of Salmonella enteric. Moreover, a total of 300 samples of poultry and poultry products were collected from different retail establishment markets in Cairo, Egypt including, 150 local whole frozen chickens, 50 imported whole frozen chickens, 100 local chicken cut samples. The highest rate of isolation 8% was obtained from imported frozen chickens and local chicken cuts, followed by local frozen chickens 6.66% and finally rectal swabs from apparently health chickens 6.4 %. Salmonella Typhimurium and Salmonella Enteritidis were most frequent among the total Salmonella isolates. Multiplex-PCR for the rapid detection of Salmonella Typhimurium and Salmonella Enteritidis from field samples especially after pre-enrichment on Rappaport-Vassiliadis (RV) selective broth (PCR-RV), revealed the same positive samples. Therefore PCR-RV technique is rabid, time saving and applicable to detect Salmonella serovars directly from chicken samples. Moreover, detecting Salmonella Typhimurium and Salmonella Enteritidis by this assay was carried out within 2 days opposed to 5–6 d by the bacteriological and serological methods.

Keywords: Salmonella enterica, Salmonella typhimurium, Salmonella enteritidis enrichment, multiplex-PCR

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Authors: Rezala Houria, Valverde Jose Luis, Romero Amaya, Molinari Alessandra, Maldotti Andrea

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The escalation of oil prices in 1973 confronted the oil industry with the problem of how to maximize the processing of crude oil, especially the heavy fractions, to give gasoline components. Strong impetus was thus given to the development of catalysts with relatively large pore sizes, which were able to deal with larger molecules than the existing molecular sieves, and with good thermal and hydrothermal stability. The oil embargo in 1973 therefore acted as a stimulus for the investigation and development of pillared clays. Iron doped titania-pillared montmorillonite clays was prepared using bentonite from deposits of Maghnia in western-Algeria. The preparation method consists of differents steps (purification of the raw bentonite, preparation of a pillaring agent solution and exchange of the cations located between the clay layers with the previously formed iron/titanium solution). The characterization of this material was carried out by X-ray fluorescence spectrometry, X-ray diffraction, textural measures by BET method, inductively coupled plasma atomic emission spectroscopy, diffuse reflectance UV visible spectroscopy, temperature- programmed desorption of ammonia and atomic absorption.This new material was investigated as photocatalyst for selective oxygenation of the liquid alkylaromatics such as: toluene, paraxylene and orthoxylene and the photocatalytic properties of it were compared with those of the titanium-pillared clays.

Keywords: iron doping, montmorillonite clays, pillared clays, oil industry

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Authors: Nawel Ouennoughi, Kamel Daoud

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During recent years, new pharmaceutical dosage forms were developed in the research laboratories and which consists of encapsulating one or more active molecules in a polymeric envelope. Several techniques of encapsulation allow obtaining the microparticles or the nanoparticles containing one or several polymers. In the industry, microencapsulation is implemented to fill the following objectives: to ensure protection, the compatibility and the stabilization of an active matter in a formulation, to carry out an adapted working, to improve the presentation of a product, to mask a taste or an odor, to modify and control the profile of release of an active matter to obtain, for example, prolonged or started effect. To this end, we focus ourselves on the encapsulation of the antidiabetic. It is an oral hypoglycemic agent belonging to the second generation of sulfonylurea’s commonly employed in the treatment of type II non-insulin-dependent diabetes in order to improve profile them dissolution. Our choice was made on the technique of encapsulation by complex coacervation with two types of polymers (gelatin and the gum Arabic) which is a physicochemical process. Several parameters were studied at the time of the formulation of the microparticles and the nanoparticles: temperature, pH, ratio of polymers etc. The microparticles and the nanoparticles obtained were characterized by microscopy, laser granulometry, FTIR and UV-visible spectrophotometry. The profile of dissolution obtained for the microparticles showed an improvement of the kinetics of dissolution compared to that obtained for the active ingredient.

Keywords: coacervation, gum Arabic, microencapsulation, gelatin

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Authors: F. Boukazouha, G. Poulin-Vittrant, M. Rguiti, M. Lethiecq

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Since its invention, by virtue of its remarkable features, the piezoelectric transformer (PT) has drawn the attention of the scientific community. In past years, it has been extensively studied and its performances have been continuously improved. Nowadays, such devices are designed in more and more sophisticated architectures with associated models describing their behavior quite accurately. However, the different studies usually carried out on such devices mainly focus on their electrical characteristics induced by direct piezoelectric effects such as voltage gain, efficiency or supplied power. In this work, we are particularly interested in the characterization of mechanical displacements induced by the inverse piezoelectric effect in a PT in vibration. For this purpose, a detailed three-dimensional finite element analysis is proposed to examine the mechanical behavior of a Rosen-type transformer made of a single bar of soft PZT (P191) and with dimensions 22mm×2.35mm×2.5mm. At the first three modes of vibration, output voltage and mechanical displacements ux, uy and uz along the length, the width and the thickness, respectively, are calculated. The amplitude of displacements varies in a range from a few nanometers to a few hundred nanometers. The validity of the simulations was successfully confirmed by experiments carried out on a prototype using a laser interferometer. A good match was observed between simulation and experimental results, especially for us at the second mode. Such 3D simulations thus appear as a helpful tool for a better understanding of mechanical phenomena in Rosen-type PT.

Keywords: piezoelectricity, gain, dispalcement, simulations

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Authors: P. L. Cheng, I. N. Umar

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Online discussion forum is a popular e-learning technique that allows participants to interact and construct knowledge. This study aims to examine the levels of participation, categories of participants and the structure of their interactions in a forum. A convenience sampling of one course coordinator and 23 graduate students was selected in this study. The forums’ log file and the Social Network Analysis software were used in this study. The analysis reveals 610 activities (including viewing forum’s topic, viewing discussion thread, posting a new thread, replying to other participants’ post, updating an existing thread and deleting a post) performed by them in this forum, with an average of 3.83 threads posted. Also, this forum consists of five at-risk participants, six bridging participants, four isolated participants and five leaders of information. In addition, the network density value is 0.15 and there exist five reciprocal interactions in this forum. The closeness value varied between 28 and 68 while the eigen vector centrality value varied between 0.008 and 0.39. The finding indicates that the participants tend to listen more rather than express their opinions in the forum. It was also revealed that those who actively provide supports in the discussion forum were not the same people who received the most responses from their peers. This study found that cliques do not exist in the forum and the participants are not selective to whom they response to, rather, it was based on the content of the posts made by their peers. Based upon the findings, further analysis with different method and population, larger sample size and a longer time frame are recommended.

Keywords: e-learning, learning management system, online forum, social network analysis

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Authors: Abdulsalam A. Al-Tamimi, Chris Peach, Paulo Rui Fernandes, Paulo J. Bartolo

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Bone fixation implants currently used to treat traumatic fractured bones and to promote fracture healing are built with biocompatible metallic materials such as stainless steel, cobalt chromium and titanium and its alloys (e.g., CoCrMo and Ti6Al4V). The noticeable stiffness mismatch between current metallic implants and host bone associates with negative outcomes such as stress shielding which causes bone loss and implant loosening leading to deficient fracture treatment. This paper, part of a major research program to design the next generation of bone fixation implants, describes the combined use of three-dimensional (3D) topology optimization (TO) and additive manufacturing powder bed technology (Electron Beam Melting) to redesign and fabricate the plates based on the current standard one (i.e., locking compression plate). Topology optimization is applied with an objective function to maximize the stiffness and constraint by volume reductions (i.e., 25-75%) in order to obtain optimized implant designs with reduced stress shielding phenomenon, under different boundary conditions (i.e., tension, bending, torsion and combined loads). The stiffness of the original and optimised plates are assessed through a finite-element study. The TO results showed actual reduction in the stiffness for most of the plates due to the critical values of volume reduction. Additionally, the optimized plates fabricated using powder bed techniques proved that the integration between the TO and additive manufacturing presents the capability of producing stiff reduced plates with acceptable tolerances.

Keywords: additive manufacturing, locking compression plate, finite element, topology optimization

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Authors: Morten Stigaard Laursen, Rasmus Nyholm Jørgensen, Henrik Skov Midtiby, Anders Krogh Mortensen, Sanmohan Baby

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This work contributes a statistical model and simulation framework yielding the best estimate possible for the potential herbicide reduction when using the MoDiCoVi algorithm all the while requiring a efficacy comparable to conventional spraying. In June 2013 a maize field located in Denmark were seeded. The field was divided into parcels which was assigned to one of two main groups: 1) Control, consisting of subgroups of no spray and full dose spraty; 2) MoDiCoVi algorithm subdivided into five different leaf cover thresholds for spray activation. In addition approximately 25% of the parcels were seeded with additional weeds perpendicular to the maize rows. In total 299 parcels were randomly assigned with the 28 different treatment combinations. In the statistical analysis, bootstrapping was used for balancing the number of replicates. The achieved potential herbicide savings was found to be 70% to 95% depending on the initial weed coverage. However additional field trials covering more seasons and locations are needed to verify the generalisation of these results. There is a potential for further herbicide savings as the time interval between the first and second spraying session was not long enough for the weeds to turn yellow, instead they only stagnated in growth.

Keywords: herbicide reduction, macrosprayer, weed crop discrimination, site-specific, sprayer boom

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Authors: Bhumika Wadhwa, Fayaz Malik

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The serine/threonine protein kinase B (PKB) also known as Akt, is one of the multifaceted kinase in human kinome, existing in three isoforms. Akt plays a vital role in phosphoinositide 3-kinase (PI3K) mediated oncogenesis in various malignancies and is one of the attractive targets for cancer drug discovery. The functional significance of an individual isoform of Akt is not redundant in cancer cell proliferation and metastasis instead Akt isoforms play distinct roles during metastasis; thereby regulating EMT. This study aims to determine isoform specific functions of Akt in cancer. The results obtained suggest that Akt1 restrict tumor invasion, whereas Akt2 promotes cell migration and invasion by various techniques like MTT, wound healing and invasion assay. Similarly, qRT-PCR also revealed that Akt3 has shown promising results in promoting cancer cell migration. Contrary to pro-oncogenic properties attributed to Akt, it is to be understood how various isoforms of Akt compensates each other in the regulation of common pathways during cancer progression and drug resistance. In conclusion, this study aims to target selective isoforms which is essential to inhibit cancer. However, the question now is whether, and how much, Akt inhibition will be tolerated in the clinic remains to be answered and the experiments will have to address the question of which combinations of newly devised Akt isoform specific inhibitors exert a favourable therapeutic effect in in vivo models of cancer to provide the therapeutic window with minimal toxicity.

Keywords: Akt isoforms, cancer, drug resistance, epithelial mesenchymal transition

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Authors: Siamak Shahidi, Nasrin Hashemi-Firouzi, Sara Soleimani-Asl, Alireza Komaki

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Introduction: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive memory and cognitive performance. Recently, an involvement of the serotonergic system and their receptors are suspected in the AD progression. In the present behavioral study, the effects of BIMU (selective 5-HT4 receptor agonist) on cognition and memory in the rat model of AD was investigated. Material and Methods: The animal model of the AD was induced by intracerebroventricular (Icv) injection of amyloid beta (Aβ) in adult male Wistar rats. Animals were divided into experimental groups included control, sham, Aβ, Aβ +BIMU groups. The treatment substances were icv injected (1 μg/μL) for thirty consecutive days. Then, novel object recognition (NOR) and passive avoidance learning (PAL) tests were applied to investigate memory and cognitive performance. Results: Aβ decrease the discrimination index of NOR test. Also, it increases the time spent in the dark compartment during PAL test, as compared with sham and control groups. In addition, compared to Aβ groups, BIMU significantly increased the discrimination index of NOR test and decreased the time spent in the dark compartment of PAL test. Conclusion: These findings suggest that 5-HT4 receptor activation prevents progression of memory and cognitive impairment in a rat model of AD.

Keywords: Alzheimer disease, cognition, memory, serotonin receptors

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Authors: Mai M. Helmy

Abstract:

Although the role of either nitric oxide (NO) or endothelin receptors modulation in the severity of cisplatin-induced nephrotoxicity has been recognized in previous studies including our own, the possible interaction between the two pathways remains obscure. In this study, we tested the possible interaction between the nitrergic and endothelin pathways in cisplatin-induced nephrotoxicity in male rats. Sprague Dawley male rats (200 to 250 g) were divided into four groups: Control (given a single dose of normal saline, i.p.), cisplatin (6 mg/kg, i.p.), cisplatin+Sildenafil (2 mg/kg, i.p.), cisplatin+Sildenafil+BQ-123 (1 mg/kg, i.p.). Each of the co-administered drugs was given in two doses; one hour before and one day after the cisplatin dose. Acute cisplatin administration resulted in significant increases in BUN and serum creatinine levels at 96 h following cisplatin injection. Increased levels of MDA, TNF-α and caspase-3, decreased nitrite/nitrate level and SOD activity in kidney homogenates were also observed following cisplatin injection. According to the obtained results, the co-adminstration of sildenafil alone with cisplatin offered a reno-protective effect comparable to that obtained following the concurrent administration of both sildenafil and the selective ETAR antagonist BQ-123. Thus, the current study is the first to reveal that the presence of an intact NO/cGMP system may offer a moderate reno-protective effect against cisplatin-induced nephrotoxicity even in the presence of ETAR-mediated vasoconstriction, suggesting the absence of obvious functional interaction between the nitrergic and endothelin pathways in cisplatin-induced nephrotoxicity in male rats.

Keywords: BQ-123, cisplatin, endothelin-1, nephrotoxicity, sildenafil

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Authors: Georgii Emelianov, Mikhail Polikarpov, Fabian Hübner, Jochen Deuse, Jochen Schiemann

Abstract:

Recycling refrigerating appliances plays a major role in protecting the Earth's atmosphere from ozone depletion and emissions of greenhouse gases. The performance of refrigerator recycling plants in terms of material retention is the subject of strict environmental certifications and is reviewed periodically through specialized audits. The continuous collection of Refrigerator data required for the input-output analysis is still mostly manual, error-prone, and not digitalized. In this paper, we propose an automated data collection system for recycling plants in order to deduce expected material contents in individual end-of-life refrigerating appliances. The system utilizes laser scanner measurements and optical data to extract attributes of individual refrigerators by applying transfer learning with pre-trained vision models and optical character recognition. Based on Recognized features, the system automatically provides material categories and target values of contained material masses, especially foaming and cooling agents. The presented data collection system paves the way for continuous performance monitoring and efficient control of refrigerator recycling plants.

Keywords: automation, data collection, performance monitoring, recycling, refrigerators

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Authors: Mateusz Szul, Tomasz Iluk, Aleksander Sobolewski

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Small-scale, distributed energy systems enabling cogeneration of heat and power based on gasification of sewage sludge, are considered as the most efficient and environmentally friendly ways of their treatment. However, economic aspects of such an investment are very demanding; therefore, for such a small scale sewage sludge gasification installation to be profitable, it needs to be efficient and simple at the same time. The article presents results of research on air gasification of sewage sludge in fixed bed GazEla reactor. Two of the most important aspects of the research considered the influence of the composition of sewage sludge blends with other feedstocks on properties of generated syngas and ash sintering problems occurring at the fixed bed. Different means of the fuel pretreatment and blending were proposed as a way of dealing with the above mentioned undesired characteristics. Influence of RDF (Refuse Derived Fuel) and biomasses in the fuel blends were evaluated. Ash properties were assessed based on proximate, ultimate, and ash composition analysis of the feedstock. The blends were specified based on complementary characteristics of such criteria as C content, moisture, volatile matter, Si, Al, Mg, and content of basic metals in the ash were analyzed, Obtained results were assessed with use of experimental gasification tests and laboratory ISO-procedure for analysis of ash characteristic melting temperatures. Optimal gasification process conditions were determined by energetic parameters of the generated syngas, its content of tars and lack of ash sinters within the reactor bed. Optimal results were obtained for co-gasification of herbaceous biomasses with sewage sludge where LHV (Lower Heating Value) of the obtained syngas reached a stable value of 4.0 MJ/Nm3 for air/steam gasification.

Keywords: ash fusibility, gasification, piston engine, sewage sludge

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Authors: Francisco Javier Montes Ruiz-Cabello, Guillermo Guerrero-Vacas, Sara Bermudez-Romero, Miguel Cabrerizo Vilchez, Miguel Angel Rodriguez-Valverde

Abstract:

Galvanized steel is one of the widespread metallic materials used in industry. It consists on a iron-based alloy (steel) coated with a layer of zinc with variable thickness. The zinc is aimed to prevent the inner steel from corrosion and staining. Its production is cheaper than the stainless steel and this is the reason why it is employed in the construction of materials with large dimensions in aeronautics, urban/ industrial edification or ski-resorts. In all these applications, turning the natural hydrophilicity of the metal surface into superhydrophobicity is particularly interesting and would open a wide variety of additional functionalities. However, producing a superhydrophobic surface on galvanized steel may be a very difficult task. Superhydrophobic surfaces are characterized by a specific surface texture which is reached either by coating the surface with a material that incorporates such texture, or by conducting several roughening methods. Since galvanized steel is already a coated material, the incorporation of a second coating may be undesired. On the other hand, the methods that are recurrently used to incorporate the surface texture leading to superhydrophobicity in metals are aggressive and may damage their surface. In this work, we used a novel strategy which goal is to produce superhydrophobic galvanized steel by a two-step non-aggressive process. The first process is aimed to create a hierarchical structure by incorporating zinc nanoparticles sintered on the surface at a temperature slightly lower than the zinc’s melting point. The second one is a hydrophobization by a thick fluoropolymer layer deposition. The wettability of the samples is characterized in terms of tilting plate and bouncing drop experiments, while the roughness is analyzed by confocal microscopy. The durability of the produced surfaces was also explored.

Keywords: galvanaized steel, superhydrophobic surfaces, sintering nanoparticles, zinc nanopowder

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Authors: Aria Vitkova, Hanna Sykulska-Lawrence

Abstract:

In recent years, Europa has been one of the major focus points in astrobiology due to its high potential of harbouring life in the vast ocean underneath its icy crust. However, the detection of life on Europa faces many challenges due to the harsh environmental conditions and mission constraints. Raman spectroscopy is a highly capable and versatile in-situ characterisation technique that does not require any sample preparation. It has only been used on Earth to date; however, recent advances in optical and laser technology have also allowed it to be considered for extraterrestrial exploration. So far, most efforts have been focused on the exploration of Mars, the most imminent planetary target. However, as an emerging technology with high miniaturization potential, Raman spectroscopy also represents a promising tool for the exploration of Europa. In this study, the capabilities of Raman technology in terms of life detection on Europa are explored and assessed. Spectra of biosignatures identified as high priority molecular targets for life detection on Europa were acquired at various excitation wavelengths and conditions analogous to Europa. The effects of extremely low temperatures and low concentrations in water ice were explored and evaluated in terms of the effectiveness of various configurations of Raman instruments. Based on the findings, a design of a miniaturized Raman instrument optimized for in-situ detection of life on Europa is proposed.

Keywords: astrobiology, biosignatures, Europa, life detection, Raman Spectroscopy

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Authors: Thanusha D. Abeywickrama, Inoka C. Perera, Genji Kurisu

Abstract:

Tuberculosis, considered being as the ninth leading cause of death worldwide, cause from a single infectious agent M. tuberculosis and the drug resistance nature of this bacterium is a continuing threat to the world. Therefore TB preventing treatment is expanding, where this study designed to analyze the regulatory mechanism of GntR transcriptional regulator gene Rv0792c, which lie between several genes codes for some hypothetical proteins, a monooxygenase and an oxidoreductase. The gene encoding Rv0792c was cloned into pET28a and expressed protein was purified to near homogeneity by Nickel affinity chromatography. It was previously reported that the protein binds within the intergenic region (BS region) between Rv0792c gene and monooxygenase (Rv0793). This resulted in binding of three protein molecules with the BS region suggesting tight control of monooxygenase as well as its own gene. Since monooxygenase plays a key role in metabolism, this gene may have a global regulatory role. The natural ligand for this regulator is still under investigation. In relation to the Rv0792 protein structure, a Circular Dichroism (CD) spectrum was carried out to determine its secondary structure elements. Percentage-wise, 17.4% Helix, 21.8% Antiparallel, 5.1% Parallel, 12.3% turn and 43.5% other were revealed from CD spectrum data under room temperature. Differential Scanning Calorimetry (DSC) was conducted to assess the thermal stability of Rv0792, which the melting temperature of protein is 57.2 ± 0.6 °C. The graph of heat capacity (Cp) versus temperature for the best fit was obtained for non-two-state model, which concludes the folding of Rv0792 protein occurs through stable intermediates. Peak area (∆HCal ) and Peak shape (∆HVant ) was calculated from the graph and ∆HCal / ∆HVant was close to 0.5, suggesting dimeric nature of the protein.

Keywords: CD spectrum, DSC analysis, GntR transcriptional regulator, protein structure

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