Search results for: molecular simulations

Authors: Sardar Ameer Akram Khan, Shahzad Amin Sheikh

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Blind equalization is an important technique amongst equalization family. Multimodulus algorithms based on blind equalization removes the undesirable effects of ISI and cater ups the phase issues, saving the cost of rotator at the receiver end. In this paper a new algorithm combination of recursive least square and Multimodulus algorithm named as RLSMMA is proposed by providing few assumption, fast convergence and minimum Mean Square Error (MSE) is achieved. The excellence of this technique is shown in the simulations presenting MSE plots and the resulting filter results.

Keywords: blind equalizations, constant modulus algorithm, multi-modulus algorithm, recursive least square algorithm, quadrature amplitude modulation (QAM)

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Authors: Mohammad Mahdi Mohammadi

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Zinc-coated steel sheets have been joined with aluminum samples in an overlapping as well as in a butt-joint configuration. A bi-metal-wire composed from aluminum and steel was used for additional welding experiments. An advantage of the laser-assisted bi-metal-wire welding is that the welding process is simplified since the primary joint between aluminium and steel exists already and laser welding occurs only between similar materials. FEM-simulations of the process were chosen to determine the ideal dimensions with respect to the formability of the bi-metal-wire. A prototype demonstrated the feasibility of the process.

Keywords: car body, steel sheets, formability of bi-metal-wire, laser-assisted bi-metal-wire

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Authors: R. Hasterok, A. Betekhtin, N. Borowska, A. Braszewska-Zalewska, E. Breda, K. Chwialkowska, R. Gorkiewicz, D. Idziak, J. Kwasniewska, M. Kwasniewski, D. Siwinska, A. Wiszynska, E. Wolny

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In contrast to animals, the organisation of plant genomes at the cytomolecular level is still relatively poorly studied and understood. However, the Brachypodium genus in general and B. distachyon in particular represent exceptionally good model systems for such study. This is due not only to their highly desirable ‘model’ biological features, such as small nuclear genome, low chromosome number and complex phylogenetic relations, but also to the rapidly and continuously growing repertoire of experimental tools, such as large collections of accessions, WGS information, large insert (BAC) libraries of genomic DNA, etc. Advanced cytomolecular techniques, such as fluorescence in situ hybridisation (FISH) with evermore sophisticated probes, empowered by cutting-edge microscope and digital image acquisition and processing systems, offer unprecedented insight into chromatin organisation at various phases of the cell cycle. A good example is chromosome painting which uses pools of chromosome-specific BAC clones, and enables the tracking of individual chromosomes not only during cell division but also during interphase. This presentation outlines the present status of molecular cytogenetic analyses of plant genome structure, dynamics and evolution using B. distachyon and some of its relatives. The current projects focus on important scientific questions, such as: What mechanisms shape the karyotypes? Is the distribution of individual chromosomes within an interphase nucleus determined? Are there hot spots of structural rearrangement in Brachypodium chromosomes? Which epigenetic processes play a crucial role in B. distachyon embryo development and selective silencing of rRNA genes in Brachypodium allopolyploids? The authors acknowledge financial support from the Polish National Science Centre (grants no. 2012/04/A/NZ3/00572 and 2011/01/B/NZ3/00177)

Keywords: Brachypodium, B. distachyon, chromosome, FISH, molecular cytogenetics, nucleus, plant genome organisation

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Authors: Ruina Xu, Peixue Jiang, Feng Luo

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The novel concept of enhanced geothermal system with CO2 instead of water as working fluid (CO2-EGS) has attracted wide attention due to additional benefit of CO2 geological storage during the power generation process. In this research, numerical investigation on a doublet CO2-EGS system is performed, focusing on the influence of the injection/production well perforation location in the targeted geothermal reservoir. Three different reservoir inlet and outlet boundary conditions are used in simulations since the well constrains are different in reality. The results show that CO2-EGS system performance of power generation and power cost vary greatly among cases of different wells perforation locations, and the optimum options under different boundary conditions are also different.

Keywords: Enhanced Geothermal System, supercritical CO2, heat transfer, CO2-EGS

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Authors: Rita Alfattal, Maryam Alfarhan, Adeeb M. Algaith, Buthaina Albash, Reem M. Elshafie, Asma Alshammari, Ahmad Alahmad, Fatima Dashti, Rasha Alsafi, Hind Alsharhan

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Defects of respiratory chain complex III (CIII) result in characteristic but rare mitochondrial disorders associated with distinct neuroradiological findings. The underlying molecular defects affecting mitochondrial CIII assembly factors are few and yet to be identified. LYRM7 assembly factor is required for proper CIII assembly where it acts as a chaperone for the Rieske iron‐sulfur (UQCRFS1) protein in the mitochondrial matrix and stabilizing it. We present here the seventeenth individual with LYRM7-associated mitochondrial leukoencephalopathy harboring a previously reported rare pathogenic homozygous LYRM 7 variant, c.2T>C, (p.Met1?). Like previously reported individuals, our 4-year-old male proband presented with recurrent metabolic and lactic acidosis, encephalopathy, and myopathy. Further, he has additional, previously unreported features, including an acute stroke like episode with bilateral central blindness and optic neuropathy, recurrent hyperglycemia and hypertension associated with metabolic crisis. However, he has no signs of psychomotor regression. He has been stable clinically with residual left-sided reduced visual acuity and amblyopia, and no more metabolic crises for 2-year-period while on the mitochondrial cocktail. Although the reported brain MRI findings in other affected individuals are homogenous, it is slightly different in our index, revealing evidence of bilateral almost symmetric multifocal periventricular T2 hyperintensities with hyperintensities of the optic nerves, optic chiasm, and corona radiata but with no cavitation or cystic changes. This report describes new clinical and radiological findings of LYRM7-associated disease. The report also summarizes the clinical and molecular data of previously reported individuals describing the full phenotypic spectrum.

Keywords: LYRM7 gene defect, mitochondrial disease, , lactic acidosis, , genetic disorder

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Authors: I. Georgousopoulou, S. Vouyiouka, C. Papaspyrides

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The hydrolytic degradation of poly(butylene succinate) (PBS) was investigated when exposed to different humidity-temperature environments. To this direction different PBS grades were submitted to hydrolysis runs. Results indicated that the increment of hydrolysis temperature and relative humidity induced significant decrease in the molecular weight and thermal properties of the bioplastic. Τhe derived data can be considered to construct degradation kinetics based on carboxyl content variation versus time.

Keywords: hydrolytic degradation, physical ageing, poly(butylene succinate), polyester

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Authors: Asma Zaib, Saeed Khan, Ayaz Ahmed Noonari, Sehrish Bint-e-Mohsin

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Breast cancer is the most common cancer among females worldwide and is estimated that more than 450,000 deaths are reported each year. It accounts for about 14% of all female cancer deaths. Angiogenesis plays an essential role in Breast cancer development, invasion, and metastasis. Breast cancer predominantly begins in luminal epithelial cells lining the normal breast ducts. Breast carcinoma likely requires coordinated efforts of both increased proliferation and increased motility to progress to metastatic stages.Resveratrol: a natural stilbenoid, has anti-inflammatory and anticancer effects that inhibits proliferation of variety of human cancer cell lines, including breast, prostate, stomach, colon, pancreatic, and thyroid cancers.The objective of this study is:To investigate anti-neoangiogenesis effects of Resveratrol in breast cancer and to analyze inhibitory effects of resveratrol on aromatase, Erα, HER2/neu, and VEGFR.Docking is the computational determination of binding affinity between molecule (protein structure and ligand).We performed molecular docking using Swiss-Dock and to determine docking effects of (1) Resveratrol with Aromatase, (2) Resveratrol with ERα (3) Resveratrol with HER2/neu and (4) Resveratrol with VEGFR2.Docking results of resveratrol determined inhibitory effects on aromatase with binding energy of -7.28 kcal/mol which shows anticancerous effects on estrogen dependent breast tumors. Resveratrol also show inhibitory effects on ERα and HER2/new with binging energy -8.02, and -6.74 respectively; which revealed anti-cytoproliferative effects upon breast cancer. On the other hand resveratrol v/s VEGFR showed potential inhibitory effects on neo-angiogenesis with binding energy -7.68 kcal/mol, angiogenesis is the important phenomenon that promote tumor development and metastasis. Resveratrol is an anti-breast cancer agent conformed by in silico studies, it has been identified that resveratrol can inhibit breast cancer cells proliferation by acting as competitive inhibitor of aromatase, ERα and HER2 neo, while neo-angiogemesis is restricted by binding to VEGFR which authenticates the anti-carcinogenic effects of resveratrol against breast cancer.

Keywords: angiogenesis, anti-cytoproliferative, molecular docking, resveratrol

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Authors: Sa’adu Mafara Abubakar, Muhammad Nuraddeen Danjuma, Adewole Tomiwa Adetunji, Richard Mundembe, Salisu Mohammed, Francis Bayo Lewu, Joseph I. Kiok

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Pearl millet is the most drought tolerant of all domesticated cereals, is cultivated extensively to feed millions of people who mainly live in hash agroclimatic zones. It serves as a major source of food for more than 40 million smallholder farmers living in the marginal agricultural lands of Northern Nigeria. Pearl millet grain is more nutritious than other cereals like maize, is also a principal source of energy, protein, vitamins, and minerals for millions of poorest people in the regions where it is cultivated. Pearl millet has recorded relatively little research attention compared with other crops and no sufficient work has analyzed its genetic diversity in north-western Nigeria. Therefore, this study was undertaken with the objectives to analyze the genetic diversity of pearl millet accessions using SSR marker and to analyze the extent of evolutionary relationship among pearl millet accessions at the molecular level. The result of the present study confirmed diversity among accessions of pearl millet in the study area. Simple Sequence Repeats (SSR) markers were used for genetic analysis and evolutionary relationship of the accessions of pearl millet. To analyze the level of genetic diversity, 8 polymorphic SSR markers were used to screen 69 accessions collected based on three maturity periods. SSR markers result reveal relationships among the accessions in terms of genetic similarities, evolutionary and ancestral origin, it also reveals a total of 53 alleles recorded with 8 microsatellites and an average of 6.875 per microsatellite, the range was from 3 to 9 alleles in PSMP2248 and PSMP2080 respectively. Moreover, both the factorial analysis and the dendrogram of phylogeny tree grouping patterns and cluster analysis were almost in agreement with each other that diversity is not clustering according to geographical patterns but, according to similarity, the result showed maximum similarity among clusters with few numbers of accessions. It has been recommended that other molecular markers should be tested in the same study area.

Keywords: pearl millet, genetic diversity, simple sequence repeat (SSR)

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Authors: Sharon-Yasotha Veerayah-Mcgregor, Valipuram Manoranjan

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A backward or inverse problem is known to be an ill-posed problem due to its instability that easily emerges with any slight change within the conditions of the problem. Therefore, only a limited number of numerical approaches are available to solve a backward problem. This paper considers the Nagumo equation, an equation that describes impulse propagation in nerve axons, which also models population growth with the Allee effect. A creative operator splitting numerical scheme is constructed to solve the inverse Nagumo equation. Computational simulations are used to verify that this scheme is stable, accurate, and efficient.

Keywords: inverse/backward equation, operator-splitting, Nagumo equation, ill-posed, finite-difference

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Authors: Fethi Benyettou, Abdelkader Aissat, M. A. Benammar

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In this work, we use Silvaco TCAD software for modeling and simulations of standard GaAs solar cell, InAs/GaAs and GaSb/GaAs p-i-n quantum dot solar cell. When comparing 20-layer InAs/GaAs, GaSb/GaAs quantum dots solar cells with standard GaAs solar cell, the conversion efficiency in simulation results increased from 16.48 % to 22.6% and 16.48% to 22.42% respectively. Also, the absorption range edge of photons with low energies extended from 900 nm to 1200 nm.

Keywords: SILVACO TCAD, the quantum dot, simulation, materials engineering

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Authors: Monika Soni, Shovonlal Bhowmick, Chandra Bhattacharya, Jitendra Sharma, Prafulla Dutta, Jagadish Mahanta

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Aedes aegypti and Aedes albopictus are considered as two major vectors to transmit dengue virus. In North-east India, two states viz. Assam and Arunachal Pradesh are known to be high endemic zone for dengue and Chikungunya viral infection. The taxonomical classification of medically important vectors are important for mapping of actual evolutionary trends and epidemiological studies. However, misidentification of mosquito species in field-collected mosquito specimens could have a negative impact which may affect vector-borne disease control policy. DNA barcoding is a prominent method to record available species, differentiate from new addition and change of population structure. In this study, a combined approach of a morphological and molecular technique of DNA barcoding was adopted to explore sequence variation in mitochondrial cytochrome c oxidase subunit I (COI) gene within dengue vectors. The study has revealed the map distribution of the dengue vector from two states i.e. Assam and Arunachal Pradesh, India. Approximate five hundred mosquito specimens were collected from different parts of two states, and their morphological features were compared with the taxonomic keys. The analysis of detailed taxonomic study revealed identification of two species Aedes aegypti and Aedes albopictus. The species aegypti comprised of 66.6% of the specimen and represented as dominant dengue vector species. The sequences obtained through standard DNA barcoding protocol were compared with public databases, viz. GenBank and BOLD. The sequences of all Aedes albopictus have shown 100% similarity whereas sequence of Aedes aegypti has shown 99.77 - 100% similarity of COI gene with that of different geographically located same species based on BOLD database search. From dengue prevalent different geographical regions fifty-nine sequences were retrieved from NCBI and BOLD databases of the same and related taxa to determine the evolutionary distance model based on the phylogenetic analysis. Neighbor-Joining (NJ) and Maximum Likelihood (ML) phylogenetic tree was constructed in MEGA6.06 software with 1000 bootstrap replicates using Kimura-2-Parameter model. Data were analyzed for sequence divergence and found that intraspecific divergence ranged from 0.0 to 2.0% and interspecific divergence ranged from 11.0 to 12.0%. The transitional and transversional substitutions were tested individually. The sequences were deposited in NCBI: GenBank database. This observation claimed the first DNA barcoding analysis of Aedes mosquitoes from North-eastern states in India and also confirmed the range expansion of two important mosquito species. Overall, this study insight into the molecular ecology of the dengue vectors from North-eastern India which will enhance the understanding to improve the existing entomological surveillance and vector incrimination program.

Keywords: COI, dengue vectors, DNA barcoding, molecular identification, North-east India, phylogenetics

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Authors: Marcin Szlachetka, Rafal Sochaczewski, Lukasz Grabowski

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This paper presents the results of the load simulations of main bearings in a two-stroke Diesel engine. A model of an engine lubrication system with connections of its main lubrication nodes, i.e., a connection of its main bearings in the engine block with the crankshaft, a connection of its crankpins with its connecting rod and a connection of its pin and its piston has been created for our calculations performed using the AVL EXCITE Designer. The analysis covers the loads given as a pressure distribution in a hydrodynamic oil film, a temperature distribution on the main bush surfaces for the specified radial clearance values as well as the impact of the force of gas on the minimum oil film thickness in the main bearings depending on crankshaft rotational speeds and temperatures of oil in the bearings. One of the main goals of the research has been to determine whether the minimum thickness of the oil film at which fluid friction occurs can be achieved for each value of crankshaft speed. Our model calculates different oil film parameters, i.e., its thickness, a pressure distribution there, the change in oil temperature. Additional enables an analysis of an oil temperature distribution on the surfaces of the bearing seats. It allows verifying the selected clearances in the bearings of the main engine under normal operation conditions and extremal ones that show a significant increase in temperature above the limit value. The research has been conducted for several engine crankshaft speeds ranging from 1000 rpm to 4000 rpm. The oil pressure in the bearings has ranged 2-5 bar according to engine speeds and the oil temperature has ranged 90-120 °C. The main bearing clearance has been adopted for the calculation and analysis as 0.025 mm. The oil classified as SAE 5W-30 has been used for the simulations. The paper discusses the selected research results referring to several specific operating points and different temperatures of the lubricating oil in the bearings. The received research results show that for the investigated main bearing bushes of the shaft, the results fall within the ranges of the limit values despite the increase in the oil temperature of the bearings reaching 120˚C. The fact that the bearings are loaded with the maximum pressure makes no excessive temperature rise on the bush surfaces. The oil temperature increases by 17˚C, reaching 137˚C at a speed of 4000 rpm. The minimum film thickness at which fluid friction occurs has been achieved for each of the operating points at each of the engine crankshaft speeds. Acknowledgement: This work has been realized in the cooperation with The Construction Office of WSK ‘PZL-KALISZ’ S.A.’ and is part of Grant Agreement No. POIR.01.02.00-00-0002/15 financed by the Polish National Centre for Research and Development.

Keywords: diesel engine, main bearings, opposing pistons, two-stroke

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Authors: Krasimira N. Zhilkova, Mariya K. Kyulavska, Roza P. Mateva

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The anionic polymerization of -caprolactam (CL) with bifunctional activators has been extensively studied as an effective and beneficial method of improving chemical and impact resistances, elasticity and other mechanical properties of polyamide (PA6). In presence of activators or macroactivators (MAs) also called polymeric activators (PACs) the anionic polymerization of lactams proceeds rapidly at a temperature range of 130-180C, well below the melting point of PA-6 (220C) permitting thus the direct manufacturing of copolymer product together with desired modifications of polyamide properties. Copolymers of PA6 with an elastic polypropylene glycol (PPG) middle block into main chain were successfully synthesized via activated anionic ring opening polymerization (ROP) of CL. Using novel PACs based on PPG polyols (with differ molecular weight) the anionic ROP of CL was realized and investigated in the presence of a basic initiator sodium salt of CL (NaCL). The PACs were synthesized as N-carbamoyllactam derivatives of hydroxyl terminated PPG functionalized with isophorone diisocyanate [IPh, 5-Isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane] and blocked then with CL units via an addition reaction. The block copolymers were analyzed and proved with 1H-NMR and FT-IR spectroscopy. The influence of the CL/PACs ratio in feed, the length of the PPG segments and polymerization conditions on the kinetics of anionic ROP, on average molecular weight, and on the structure of the obtained block copolymers were investigated. The structure and phase behaviour of the copolymers were explored with differential scanning calorimetry, wide-angle X-ray diffraction, thermogravimetric analysis and dynamic mechanical thermal analysis. The crystallinity dependence of PPG content incorporated into copolymers main backbone was estimate. Additionally, the mechanical properties of the obtained copolymers were studied by notched impact test. From the performed investigation in this study could be concluded that using PPG based PACs at the chosen ROP conditions leads to obtaining well-defined PA6-b-PPG-b-PA6 copolymers with improved impact resistance.

Keywords: anionic ring opening polymerization, caprolactam, polyamide copolymers, polypropylene glycol

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Authors: Ridha Zgolli, Ahmed Belhaj, Maroua Ennouri

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This study presents a new method to predict cavitation area that may be eroded. It is based on the post-treatment of URANS simulations in cavitant flows. The most RANS calculations with incompressible consideration are based on cavitation model using mixture fluid with density (ρm) calculated as a function of liquid density (ρliq), vapour or gas density (ρvap) and vapour or gas volume fraction α (ρm = αρvap + (1-α) ρliq). The calculations are performed on hydrofoil geometries and compared with experimental works concerning flows characteristics (size of pocket, pressure, velocity). We present here the used cavitation model and the approach followed to evaluate the value of α fixing the shape of pocket around wall before collapsing.

Keywords: flows, CFD, cavitation, erosion

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Authors: Sunil K. Jena, Sanjaya K. Samal, Mahesh Chand, Abhay T. Sangamwar

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Tamoxifen (TMX) and its analogues are approved as a first line therapy for the treatment of estrogen receptor-positive tumors. However, clinical development of TMX has been hampered by its low bioavailability and severe hepatotoxicity. Herein, we attempt to design a new drug delivery vehicle that could enhance the pharmacokinetic performance of TMX. Initially, high-molecular weight carboxymethyl chitosan was hydrolyzed to low-molecular weight carboxymethyl chitosan (LMW CMC) with hydrogen peroxide under the catalysis of phosphotungstic acid. Amphiphilic block copolymers of LMW CMC were synthesized via amidation reaction between the carboxyl group of α-tocopherol succinate (TS) and an amine group of LMW CMC. These amphiphilic block copolymers were self-assembled to nanosize core-shell-structural micelles in the aqueous medium. The critical micelle concentration (CMC) decreased with the increasing substitution of TS on LMW CMC, which ranged from 1.58 × 10-6 to 7.94 × 10-8 g/mL. Maximum TMX loading up to 8.08 ± 0.98% was achieved with Cmc-TS4.5 (TMX/Cmc-TS4.5 with 1:8 weight ratio). Both blank and TMX-loaded polymeric micelles (TMX-PM) of Cmc-TS4.5 exhibits spherical shape with the particle size below 200 nm. TMX-PM has been found to be stable in the gastrointestinal conditions and released only 44.5% of the total drug content by the first 72 h in simulated gastric fluid (SGF), pH 1.2. However, the presence of pepsin does not significantly increased the TMX release in SGF, pH 1.2, released only about 46.2% by the first 72 h suggesting its inability to cleave the peptide bond. In contrast, the release of TMX from TMX-PM4.5 in SIF, pH 6.8 (without pancreatin) was slow and sustained, released only about 10.43% of the total drug content within the first 30 min and nearly about 12.41% by the first 72 h. The presence of pancreatin in SIF, pH 6.8 led to an improvement in drug release. About 28.09% of incorporated TMX was released in the presence of pancreatin in 72 h. A cytotoxicity study demonstrated that TMX-PM exhibited time-delayed cytotoxicity in human MCF-7 breast cancer cells. Pharmacokinetic studies on Sprague-Dawley rats revealed a remarkable increase in oral bioavailability (1.87-fold) with significant (p < 0.0001) enhancement in AUC0-72 h, t1/2 and MRT of TMX-PM4.5 than that of TMX-suspension. Thus, the results suggested that CMC-TS micelles are a promising carrier for TMX delivery.

Keywords: carboxymethyl chitosan, d-α-tocopherol succinate, pharmacokinetic, polymeric micelles, tamoxifen

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Authors: Douhi Reda Bouabdellah, Khalafi Hamid, Belamri Samir

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The desire to improve the safety of nuclear reactor containment has revealed the need for data on the thermo mechanical behavior of concrete in case of accident during which the concrete is exposed to high temperatures. The aim of the present work is to study the influence of high temperature on the behavior of ordinary concrete specimens loaded by an effort of compression. A thermal model is developed by discretization volume elements (CASTEM). The results of different simulations, combined with other findings help to bring a physical phenomenon explanation Thermo mechanical concrete structures, which allowed to obtain the variation of the stresses anywhere in point or node and each subsequent temperature different directions X, Y and Z.

Keywords: concrete, thermic-gradient, fire resistant, simulation by CASTEM, mechanical strength

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Authors: Piotr J. Skusiewicz, Johnathan Saul, Ijhar Rusli, Svetlana Aleksandrova, Stephen. F. Benjamin, Miroslaw Gall, Steve Pierson, Carol A. Roberts

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The application of turbocharging in automotive engines leads to swirling flow entering the catalyst. The behaviour of this type of flow within the catalyst has yet to be adequately documented. This work discusses the effect of swirling flow on the flow distribution in automotive exhaust catalysts. Compressed air supplied to a moving-block swirl generator allowed for swirling flow with variable intensities to be generated. Swirl intensities were measured at the swirl generator outlet using single-sensor hot-wire probes. The swirling flow was fed into diffusers with total angles of 10°, 30° and 180°. Downstream of the diffusers, a wash-coated diesel oxidation catalyst (DOC) of length 143.8 mm, diameter 76.2 mm and nominal cell density of 400 cpsi was fitted. Velocity profiles were measured at the outlet sleeve about 30 mm downstream of the monolith outlet using single-sensor hot-wire probes. Wall static pressure was recorded using a multi-tube manometer connected to pressure taps positioned along the diffuser walls. The results show that as swirl is increased, more of the flow is directed towards the diffuser walls. The velocity decreases around the centre-line and maximum velocities are observed close to the outer radius of the monolith for all flow rates. At the maximum swirl intensity, reversed flow was recorded near the centre of the monolith. Wall static pressure measurements in the 180° diffuser indicated no pressure recovery as the flow enters the diffuser. This is indicative of flow separation at the inlet to the diffuser. To gain insight into the flow structure, CFD simulations have been performed for the 180° diffuser for a flow rate of 63 g/s. The geometry of the model consists of the complete assembly from the upstream swirl generator to the outlet sleeve. Modelling of the flow in the monolith was achieved using the porous medium approach, where the monolith with parallel flow channels is modelled as a porous medium that resists the flow. A reasonably good agreement was achieved between the experimental and CFD results downstream of the monolith. The CFD simulations allowed visualisation of the separation zones and central toroidal recirculation zones that occur within the expansion region at certain swirl intensities which are highlighted.

Keywords: catalyst, computational fluid dynamics, diffuser, hot-wire anemometry, swirling flow

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Authors: Maryam Ebrahimpour, Amir Ebrahimi

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This paper presents the steady-state amplitude analysis of MOS Colpitts oscillator with short channel device. The proposed method is based on a large signal analysis and the nonlinear differential equations that govern the oscillator circuit behaviour. Also, the short channel effects are considered in the proposed analysis and analytical equations for finding the steady-state oscillation amplitude are derived. The output voltage calculated from this analysis is in excellent agreement with simulations for a wide range of circuit parameters.

Keywords: colpitts oscillator, CMOS, electronics, circuits

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Authors: Paulomi (Polly) Burey, Zoe Lynch

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In STEM education, students often have difficulty linking static images and words from textbooks or online resources, to the underlying mechanisms of the topic of study. This can often dissuade some students from pursuing study in the physical and chemical sciences. A growing movement in current day students demonstrates that the YouTube generation feel they learn best from video or dynamic, interactive learning tools, and will seek these out as alternatives to their textbooks and the classroom learning environment. Chemistry, and in particular visualization of molecular structures in everyday materials, can prove difficult to comprehend without significant interaction with the teacher of the content and concepts, beyond the timeframe of a typical class. This can cause a learning hurdle for distance education students, and so it is necessary to provide strong electronic tools and resources to aid their learning. As one of the electronic resources, an animation design approach to link everyday materials to their underlying chemistry would be beneficial for student learning, with the focus here being on food. These animations were designed and storyboarded with a scaling approach and commence with a focus on the food material itself and its component parts. This is followed by animated transitions to its underlying microstructure and identifying features, and finally showing the molecules responsible for these microstructural features. The animation ends with a reverse transition back through the molecular structure, microstructure, all the way back to the original food material, and also animates some reactions that may occur during food processing to demonstrate the purpose of the underlying chemistry and how it affects the food we eat. Using this cyclical approach of linking students’ existing knowledge of food to help guide them to understanding more complex knowledge, and then reinforcing their learning by linking back to their prior knowledge again, enhances student understanding. Food is also an ideal material system for students to interact with, in a hands-on manner to further reinforce their learning. These animations were launched this year in a 2nd year University Food Chemistry course with improved learning outcomes for the cohort.

Keywords: chemistry, food science, future pedagogy, STEM Education

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Authors: H. Abaal, R. Skouri

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A power flow analysis is a steady-state study of power grid. The goal of power flow analysis is to determine the voltages, currents, and real and reactive power flows in a system under a given load conditions. In this paper, the load flow analysis program by Newton Raphson polar coordinates Method is developed. The effectiveness of the developed program is evaluated through a simple 5-IEEE test system bus by simulations using MATLAB.

Keywords: power flow analysis, Newton Raphson polar coordinates method

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Authors: L. Ebralidze, A. Tsertsvadze, D. Berashvili, A. Bakuridze

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Current cancer therapy strategies are based on surgery, radiotherapy and chemotherapy. The problems associated with chemotherapy are one of the biggest challenges for clinical medicine. These include: low specificity, broad spectrum of side effects, toxicity and development of cellular resistance. Therefore, anti-cance drugs need to be develop urgently. Particularly, in order to increase efficiency of anti-cancer drugs and reduce their side effects, scientists work on formulation of nano-drugs. The objective of this study was to develop composition and technology of vincristine nanoparticles using high-molecular carbohydrates of plant origin. Plant polysacharides, particularly, soy bean seed polysaccharides, flaxseed polysaccharides, citrus pectin, gum arabic, sodium alginate were used as objects. Based on biopharmaceutical research, vincristine containing nanoparticle formulations were prepared. High-energy emulsification and solvent evaporation methods were used for preparation of nanosystems. Polysorbat 80, polysorbat 60, sodium dodecyl sulfate, glycerol, polyvinyl alcohol were used in formulation as emulsifying agent and stabilizer of the system. The ratio of API and polysacharides, also the type of the stabilizing and emulsifying agents are very effective on the particle size of the final product. The influence of preparation technology, type and concentration of stabilizing agents on the properties of nanoparticles were evaluated. For the next stage of research, nanosystems were characterized. Physiochemical characterization of nanoparticles: their size, shape, distribution was performed using Atomic force microscope and Scanning electron microscope. The present study explored the possibility of production of NPs using plant polysaccharides. Optimal ratio of active pharmaceutical ingredient and plant polysacharids, the best stabilizer and emulsifying agent was determined. The average range of nanoparticles size and shape was visualized by SEM.

Keywords: nanoparticles, target delivery, natural high molecule carbohydrates, surfactants

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Authors: David Nagy

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This paper exemplifies the influence of the purpose of an aircraft on the aerodynamic properties of its airfoil. In particular, the research takes into consideration two types of aircraft, namely cargo aircraft and military high-speed aircraft and compares their airfoil characteristics using their NACA airfoils as well as computational fluid dynamics. The results show that airfoils of aircraft designed for cargo have a heavier focus on maintaining a large lift force whereas speed-oriented airplanes focus on minimizing the drag force.

Keywords: aerodynamic simulation, aircraft, airfoil, computational fluid dynamics, lift to drag ratio, NACA 64-206, NACA 65-415

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Authors: R. Ziaie Moayed, B. Mohammadi-Haji

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Stone columns have been widely employed to improve the load-settlement characteristics of soft soils. The results of two small scale displacement control loading tests on stone columns were used in order to validate numerical finite element simulations. Additionally, a series of numerical calculations of static loading have been performed on strengthened raft footing to investigate the effects of using stone columns on bearing capacity of footings. The bearing capacity of single and group of stone columns under static loading compares with unimproved ground.

Keywords: circular raft footing, numerical analysis, validation, vertically encased stone column

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Authors: Irena Kostovska, Katerina Tosheska Trajkovska, Svetlana Cekovska, Julijana Brezovska Kavrakova, Hristina Ampova, Sonja Topuzovska, Ognen Kostovski, Goce Spasovski, Danica Labudovic

Abstract:

Background: Proteinuria is an important feature of secondary nephropathies. The quantitative and qualitative analysis of proteinuria plays an important role in determining the types of proteinuria (glomerular, tubular and mixed), in the diagnosis and prognosis of secondary nephropathies. The damage of the glomerular basement membrane is responsible for a proteinuria characterized by the presence of large amounts of protein with high molecular weights such as albumin (69 kilo Daltons-kD), transferrin (78 kD) and immunoglobulin G (150 kD). An insufficiency of proximal tubular function is the cause of a proteinuria characterized by the presence of proteins with low molecular weight (LMW), such as retinol binding protein (21 kD) and α1-microglobulin (31 kD). In some renal diseases, a mixed glomerular and tubular proteinuria is frequently seen. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) is the most widely used method of analyzing urine proteins for clinical purposes. The main aim of the study is to determine the type of proteinuria in the most common secondary nephropathies such as diabetic, hypertensive nephropathy and preeclampsia. Material and methods: In this study were included 90 subjects: subjects with diabetic nephropathy (n=30), subjects with hypertensive nephropahty (n=30) and pregnant women with preeclampsia (n=30). We divided all subjects according to UM/CR into three subgroups: macroalbuminuric (UM/CR >300 mg/g), microalbuminuric (UM/CR 30-300 mg/g) and normolabuminuric (UM/CR<30 mg/g). In all subjects, we measured microalbumin and creatinine in urine with standard biochemical methods. Separation of urinary proteins was performed by SDS-PAGE, in several stages: linear gel preparation (4-22%), treatment of urinary samples before their application on the gel, electrophoresis, gel fixation, coloring with Coomassie blue, and identification of the separated protein fractions based on standards with exactly known molecular weight. Results: According to urinary microalbumin/creatinin ratio in group of subject with diabetic nephropathy, nine patients were macroalbuminuric, while 21 subject were microalbuminuric. In group of subjects with hypertensive nephropathy, we found macroalbuminuria (n=4), microalbuminuria (n=20) and normoalbuminuria (n=6). All pregnant women with preeclampsia were macroalbuminuric. Electrophoretic separation of urinary proteins showed that in macroalbuminric patients with diabetic nephropathy 56% have mixed proteinuria, 22% have glomerular proteinuria and 22% have tubular proteinuria. In subgroup of subjects with diabetic nephropathy and microalbuminuria, 52% have glomerular proteinuria, 8% have tubular proteinuria, and 40% of subjects have normal electrophoretic findings. All patients with maroalbuminuria and hypertensive nephropathy have mixed proteinuria. In subgroup of patients with microalbuminuria and hypertensive nephropathy, we found: 32% with mixed proteinuria, 27% with normal findings, 23% with tubular, and 18% with glomerular proteinuria. In all normoalbuminruic patiens with hypertensive nephropathy, we detected normal electrophoretic findings. In group of subjects pregnant women with preeclampsia, we found: 81% with mixed proteinuria, 13% with glomerular, and 8% with tubular proteinuria. Conclusion: By SDS PAGE method, we detected that in patients with secondary nephropathies the most common type of proteinuria is mixed proteinuria, indicating both loss of glomerular permeability and tubular function. We can conclude that SDS PAGE is high sensitive method for detection of renal impairment in patients with secondary nephropathies.

Keywords: diabetic nephropathy, preeclampsia, hypertensive nephropathy, SDS PAGE

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Authors: Umut Yıldız, Berkin Kurtuluş, Yunus Emre Muslubaş

Abstract:

Thrust vectoring, especially in military aviation, is a concept that sees much use to improve maneuverability in already agile aircraft. As this concept is fairly new and cost intensive to design and test, computational methods are useful in easing the preliminary design process. Computational Fluid Dynamics (CFD) can be utilized in many forms to simulate nozzle flow, and there exist various CFD studies in both 2D mechanical and 3D injection based thrust vectoring, and yet, 3D mechanical thrust vectoring analyses, at this point in time, are lacking variety. Additionally, the freely available test data is constrained to limited pitch angles and geometries. In this study, based on a test case provided by NASA, both steady and unsteady 3D CFD simulations are conducted to examine the aerodynamic performance of a mechanical thrust vectoring nozzle model and to validate the utilized numerical model. Steady analyses are performed to verify the flow characteristics of the nozzle at pitch angles of 0, 10 and 20 degrees, and the results are compared with experimental data. It is observed that the pressure data obtained on the inner surface of the nozzle at each specified pitch angle and under different flow conditions with pressure ratios of 1.5, 2 and 4, as well as at azimuthal angle of 0, 45, 90, 135, and 180 degrees exhibited a high level of agreement with the corresponding experimental results. To validate the CFD model, the insights from the steady analyses are utilized, followed by unsteady analyses covering a wide range of pitch angles from 0 to 20 degrees. Throughout the simulations, a mesh morphing method using a carefully calculated mathematical shape deformation model that simulates the vectored nozzle shape exactly at each point of its travel is employed to dynamically alter the divergent part of the nozzle over time within this pitch angle range. The mesh morphing based vectored nozzle shapes were compared with the drawings provided by NASA, ensuring a complete match was achieved. This computational approach allowed for the creation of a comprehensive database of results without the need to generate separate solution domains. The database contains results at every 0.01° increment of nozzle pitch angle. The unsteady analyses, generated using the morphing method, are found to be in excellent agreement with experimental data, further confirming the accuracy of the CFD model.

Keywords: thrust vectoring, computational fluid dynamics, 3d mesh morphing, mathematical shape deformation model

Procedia PDF Downloads 67

Authors: V. K. Srivastava

Abstract:

Graphene has recently attracted an increasing attention in nanocomposites applications because it has 200 times greater strength than steel, making it the strongest material ever tested. Graphene, as the fundamental two-dimensional (2D) carbon structure with exceptionally high crystal and electronic quality, has emerged as a rapidly rising star in the field of material science. Graphene, as defined, as a 2D crystal, is composed of monolayers of carbon atoms arranged in a honeycombed network with six-membered rings, which is the interest of both theoretical and experimental researchers worldwide. The name comes from graphite and alkene. Graphite itself consists of many graphite-sheets stacked together by weak van der Waals forces. This is attributed to the monolayer of carbon atoms densely packed into honeycomb structure. Due to superior inherent properties of graphene nanoplatelets (GnP) over other nanofillers, GnP particles were added in epoxy resin with the variation of weight percentage. It is indicated that the DMA results of storage modulus, loss modulus and tan δ, defined as the ratio of elastic modulus and imaginary (loss) modulus versus temperature were affected with addition of GnP in the epoxy resin. In epoxy resin, damping (tan δ) is usually caused by movement of the molecular chain. The tan δ of the graphene nanoplatelets/epoxy resin composite is much lower than that of epoxy resin alone. This finding suggests that addition of graphene nanoplatelets effectively impedes movement of the molecular chain. The decrease in storage modulus can be interpreted by an increasing susceptibility to agglomeration, leading to less energy dissipation in the system under viscoelastic deformation. The results indicates the tan δ increased with the increase of temperature, which confirms that tan δ is associated with magnetic field strength. Also, the results show that the nanohardness increases with increase of elastic modulus marginally. GnP filled epoxy resin gives higher value than the epoxy resin, because GnP improves the mechanical properties of epoxy resin. Debonding of GnP is clearly observed in the micrograph having agglomeration of fillers and inhomogeneous distribution. Therefore, DMA and nanohardness studies indiacte that the elastic modulus of epoxy resin is increased with the addition of GnP fillers.

Keywords: agglomeration, elastic modulus, epoxy resin, graphene nanoplatelet, loss modulus, nanohardness, storage modulus

Procedia PDF Downloads 253

Authors: I. Baddari, A. Riahla, M. Mezghich

Abstract:

Today in the literature, we discover a lot of routing algorithms which some have been the subject of normalization. Two great classes Routing algorithms are defined, the first is the class reactive algorithms and the second that of algorithms proactive. The aim of this work is to make a comparative study between some routing algorithms. Two comparisons are considered. The first will focus on the protocols of the same class and second class on algorithms of different classes (one reactive and the other proactive). Since they are not based on analytical models, the exact evaluation of some aspects of these protocols is challenging. Simulations have to be done in order to study their performances. Our simulation is performed in NS2 (Network Simulator 2). It identified a classification of the different routing algorithms studied in a metrics such as loss of message, the time transmission, mobility, etc.

Keywords: ad-hoc network routing protocol, simulation, NS2, delay, packet loss, wideband, mobility

Procedia PDF Downloads 383

Authors: Nwogiji Cletus Olando, Oselebe Happiness Ogba, Enoch Achigan-Dako

Abstract:

Digitaria iburua, commonly known as black fonio, is a cereal crop native to Africa and extensively cultivated by smallholder farmers in Northern Benin, Togo, and Nigeria. This crop holds immense nutritional and socio-cultural value. Unfortunately, limited knowledge about its genetic diversity exists due to a lack of scientific attention. As a result, its potential for improvement in food and agriculture remains largely untapped. To address this gap, a study was conducted using 41 accessions of D. iburua stored in the genebank of the Laboratory of Genetics, Biotechnology, and Seed Science at Abomey-Calavi University, Benin. The study employed both morphological and simple sequence repeat (SSR) markers to evaluate the genetic variability of the accessions. Agro-morphological assessments were carried out during the 2020 cropping season, utilizing an alpha lattice design with three replications. The collected data encompassed qualitative and quantitative traits. Additionally, molecular variability was assessed using eleven SSR markers. The results revealed significant phenotypic variability among the evaluated accessions, leading to their classification into three main clusters. Furthermore, the eleven SSR markers identified a total of 50 alleles, averaging 4.55 alleles per locus. The primers exhibited an average polymorphic information content value of 0.43, with the DE-ARC019 primer displaying the highest value (0.59). These findings suggest a substantial degree of genetic heterogeneity within the evaluated accessions, and the SSR markers employed in the study proved highly effective in detecting and characterizing this genetic variability. In conclusion, this study highlights the presence of significant genetic diversity in black fonio and provides valuable insights for future efforts aimed at its genetic improvement and conservation.

Keywords: genetic diversity, digitaria iburua, genetic improvement, simple sequence repeat markers, Nigeria, conservation

Procedia PDF Downloads 74

Authors: Dongjoo Kim

Abstract:

Effective control of sloshing in a liquid container is an important issue to be resolved in many applications. In this study, numerical simulations are performed to design the velocity profile of rectangular container and investigate the effectiveness of input shaping for sloshing control. Trapezoidal profiles of container velocity are chosen to be reference commands and they are convolved with a series of impulses to generate shaped ones that induce minimal residual oscillations. The performances of several input shapers are compared from the viewpoint of transient peak and residual oscillations of sloshing. Results show that sloshing can be effectively controlled by input shaping (Supported by the NRF programs, NRF-2015R1D1A1A01059675, of Korean government).

Keywords: input shaping, rectangular container, sloshing, trapezoidal profile

Procedia PDF Downloads 241

Authors: Piotr Jerzy Rugor, Julia Wajoras

Abstract:

The presented work regards a single-stage aerodynamically controlled solid propulsion rocket. Steering a rocket to fly along a predetermined trajectory can be beneficial for minimizing aerodynamic losses and achieved by implementing an active control system on board. In this particular case, a canard configuration has been chosen, although other methods of control have been considered and preemptively analyzed, including non-aerodynamic ones. The objective of this work is to create a system capable of guiding the rocket, focusing on roll stabilization. The paper describes initial analysis of the problem, covers the main challenges of missile guidance and presents data acquired during the experimental study.

Keywords: active canard control system, rocket design, numerical simulations, flight optimization

Procedia PDF Downloads 181