Search results for: multi drug resistance

Authors: Mousa Meratizaman, Sina Monadizadeh, Majid Amidpour

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One of the most favorable thermal desalination methods used widely today is Multi Effect Desalination. High energy consumption in this method causes coupling it with high temperature power cycle like gas turbine. This combination leads to higher energy efficiency. One of the high temperature power systems which have cogeneration opportunities is Solid Oxide Fuel Cell / Gas Turbine. Integration of Multi Effect Desalination with Solid Oxide Fuel Cell /Gas Turbine power cycle in a range of 300-1000 kW is considered in this article. The exhausted heat of Solid Oxide Fuel Cell /Gas Turbine power cycle is used in Heat Recovery Steam Generator to produce needed motive steam for Desalination unit. Thermodynamic simulation and parametric studies of proposed system are carried out to investigate the system performance.

Keywords: solid oxide fuel cell, thermodynamic simulation, multi effect desalination, gas turbine hybrid cycle

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Authors: Chee Wee Gan, Anthony Herr Cheun Ng, Yee Shan Wong, Subbu Venkatraman, Lynne Hsueh Yee Lim

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Otitis media with effusion (OME) is the leading cause of hearing loss in children worldwide. Surgery to insert grommet tube into the eardrum is usually indicated for OME unresponsive to antimicrobial therapy. It is the most common surgery for children. However, current commercially available grommet tubes are non-bioresorbable, not drug-treated, with unpredictable duration of retention on the eardrum to ventilate middle ear. Their functionality is impaired when clogged or chronically infected, requiring additional surgery to remove/reinsert grommet tubes. We envisaged that a novel fully bioresorbable grommet tube with sustained antibiotic release technology could address these drawbacks. In this study, drug-loaded bioresorbable poly(L-lactide-co-ε-caprolactone)(PLC) copolymer grommet tubes were fabricated by microinjection moulding technique. In vitro drug release and degradation model of PLC tubes were studied. Antibacterial property was evaluated by incubating PLC tubes with P. aeruginosa broth. Surface morphology was analyzed using scanning electron microscopy. A preliminary animal study was conducted using guinea pigs as an in vivo model to evaluate PLC tubes with and without drug, with commercial Mini Shah grommet tube as comparison. Our in vitro data showed sustained drug release over 3 months. All PLC tubes revealed exponential degradation profiles over time. Modeling predicted loss of tube functionality in water to be approximately 14 weeks and 17 weeks for PLC with and without drug, respectively. Generally, PLC tubes had less bacteria adherence, which were attributed to the much smoother tube surfaces compared to Mini Shah. Antibiotic from PLC tube further made bacteria adherence on surface negligible. They showed neither inflammation nor otorrhea after 18 weeks post-insertion in the eardrums of guinea pigs, but had demonstrated severe degree of bioresorption. Histology confirmed the new PLC tubes were biocompatible. Analyses on the PLC tubes in the eardrums showed bioresorption profiles close to our in vitro degradation models. The bioresorbable antibiotic-loaded grommet tubes showed good predictability in functionality. The smooth surface and sustained release technology reduced the risk of tube infection. Tube functional duration of 18 weeks allowed sufficient ventilation period to treat OME. Our ongoing studies include modifying the surface properties with protein coating, optimizing the drug dosage in the tubes to enhance their performances, evaluating their functional outcome on hearing after full resoption of grommet tube and healing of eardrums, and developing animal model with OME to further validate our in vitro models.

Keywords: bioresorbable polymer, drug release, grommet tube, guinea pigs, otitis media with effusion

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Authors: Shobha G. Ranjan

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Cloud computing is an emerging, on-demand and internet- based technology. Varieties of services like, software, hardware, data storage and infrastructure can be shared though the cloud computing. This technology is highly reliable, cost effective and scalable in nature. It is a must only the authorized users should access these services. Further the time granted to access these services should be taken into account for proper accounting purpose. Currently many organizations do the security measures in many different ways to provide the best cloud infrastructure to their clients, but that’s not the limitation. This paper presents the multi-level security measure technique which is in accordance with the OSI model. In this paper, details of proposed multilevel security measures technique are presented along with the architecture, activities, algorithms and probability of success in breaking authentication.

Keywords: cloud computing, cloud security, integrity, multi-tenancy, security

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Authors: Lin Feng, Ling-Ling E., Hong-Chen Liu

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The development of chemoresistance in patients represents a major challenge in cancer treatment. Lactate dehydrogenase‑A (LDHA) is one of the principle isoforms of LDH that is expressed in breast tissue, controlling the conversion of pyruvate to lactate and also playing a significant role in the metabolism of glucose. The aim of this study was to identify whether LDHA was involved in oral cancer cell resistance to Taxol and whether the downregulation of LDHA, as a result of cisplatin treatment, may overcome Taxol resistance in human oral squamous cells. The OECM‑1 oral epidermal carcinoma cell line was used, which has been widely used as a model of oral cancer in previous studies. The role of LDHA in Taxol and cisplatin resistance was investigated and the synergistic cytotoxicity of cisplatin and/or Taxol in oral squamous cells was analyzed. Cell viability was analyzed by MTT assay, LDHA expression was analyzed by western blot analysis and siRNA transfection was performed to knock down LDHA expression. The present study results showed that decreased levels of LDHA were responsible for the resistance of oral cancer cells to cisplatin (CDDP). CDDP treatments downregulated LDHA expression and lower levels of LDHA were detected in the CDDP‑resistant oral cancer cells compared with the CDDP‑sensitive cells. By contrast, the Taxol‑resistant cancer cells showed elevated LDHA expression levels. In addition, small interfering RNA‑knockdown of LDHA sensitized the cells to Taxol but desensitized them to CDDP treatment while exogenous expression of LDHA sensitized the cells to CDDP, but desensitized them to Taxol. The present study also revealed the synergistic cytotoxicity of CDDP and Taxol for killing oral cancer cells through the inhibition of LDHA. This study highlights LDHA as a novel therapeutic target for overcoming Taxol resistance in oral cancer patients using the combined treatments of Taxol and CDDP.

Keywords: cisplatin, Taxol, carcinoma, oral squamous cells

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Authors: Mani Mofidi, Neda Valizadeh, Ali Hashemaghaee, Mona Hashemaghaee, Soudabeh Shafiee Ardestani

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Background: Acute pain and its management remained the most complaint of emergency service admission. Diagnostic and therapeutic procedures add to patients’ pain. Diminishing the pain increases the quality of patient’s feeling and improves the patient-physician relationship. Aim: The aim of this study was to evaluate the outcomes and side effects of opioid administration in emergency patients. Material and Methods: patients admitted to ward II emergency service of Imam Khomeini hospital, who received one of the opioids: morphine, pethidine, methadone or fentanyl as an analgesic were evaluated. Their vital signs and general condition were examined before and after drug injection. Also, patient’s pain experience were recorded as numerical rating score (NRS) before and after analgesic administration. Results: 268 patients were studied. 34 patients were addicted to opioid drugs. Morphine had the highest rate of prescription (86.2%), followed by pethidine (8.5%), methadone (3.3%) and fentanyl (1.68). While initial NRS did not show significant difference between addicted patients and non-addicted ones, NRS decline and its score after drug injection were significantly lower in addicted patients. All patients had slight but statistically significant lower respiratory rate, heart rate, blood pressure and O2 saturation. There was no significant difference between different kind of opioid prescription and its outcomes or side effects. Conclusion: Pain management should be always in physicians’ mind during emergency admissions. It should not be assumed that an addicted patient complaining of pain is malingering to receive drug. Titration of drug and close monitoring must be in the curriculum to prevent any hazardous side effects.

Keywords: numerical rating score, opioid, pain, emergency department

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Authors: Uyanga Sukhbaatar, Ahmed Lbath, Mendamar Majig

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The Orienteering Problem is the most known example to start modeling tourist trip design problem. In order to meet tourist’s interest and constraint the OP is becoming more and more complicate to solve. The Multi Constraint Team Orienteering Problem with Time Windows is the last extension of the OP which differentiates from other extensions by including more extra associated constraints. The goal of the MCTOPTW is maximizing tourist’s satisfaction score in same time not to violate any of these constraints. This paper presents a genetic algorithmic approach to tackle the MCTOPTW. The benchmark data from literature is tested by our algorithm and the performance results are compared.

Keywords: multi constraint team orienteering problem with time windows, genetic algorithm, tour planning system

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Authors: Driss Cherqaoui, Nouhaila Ait Lahcen, Ismail Hdoufane, Mehdi Oubahmane, Wissal Liman, Christelle Delaite, Mohammed M. Alanazi

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The Ebola virus is a highly contagious and deadly pathogen that causes Ebola virus disease. The Ebola virus glycoprotein (EBOV-GP) is a key factor in viral entry into host cells, making it a critical target for therapeutic intervention. Using a combination of computational approaches, this study focuses on the identification of natural compounds that could serve as potent inhibitors of EBOV-GP. The 3D structure of EBOV-GP was selected, with missing residues modeled, and this structure was minimized and equilibrated. Two large natural compound databases, COCONUT and NPASS, were chosen and filtered based on toxicity risks and Lipinski’s Rule of Five to ensure drug-likeness. Following this, a pharmacophore model, built from 22 reported active inhibitors, was employed to refine the selection of compounds with a focus on structural relevance to known Ebola inhibitors. The filtered compounds were subjected to virtual screening via molecular docking, which identified ten promising candidates (five from each database) with strong binding affinities to EBOV-GP. These compounds were then validated through molecular dynamics simulations to evaluate their binding stability and interactions with the target. The top three compounds from each database were further analyzed using ADMET profiling, confirming their favorable pharmacokinetic properties, stability, and safety. These results suggest that the selected compounds have the potential to inhibit EBOV-GP, offering new avenues for antiviral drug development against the Ebola virus.

Keywords: EBOV-GP, Ebola virus glycoprotein, high-throughput drug screening, molecular docking, molecular dynamics, natural compounds, pharmacophore modeling, virtual screening

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Authors: Amthal Al-Gailani, Olujide Sanni, Thibaut Charpentier, Anne Neville

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Formation of inorganic scale on heat transfer surfaces is a serious problem encountered in industrial, commercial, and domestic heat exchangers and systems. Several industries use potable/groundwater sources such as rivers, lakes, and oceans to use water as a working fluid in heat exchangers and steamers. As potable/surface water contains diverse salt ionic species, the scaling kinetics and deposit morphology are expected to be different from those found in artificially hardened solutions. In this work, scale formation on the heat transfer surfaces from potable water has been studied using a once-through open flow cell under atmospheric pressure. The surface scaling mechanism and deposit morphology are investigated at high surface temperature. Thus the water evaporation process has to be considered. The effect of surface temperature, flow rate, and inhibitor deployment on the thermal resistance and morphology of the scale have been investigated. The study findings show how an increase in surface temperature enhances the crystallization reaction kinetics on the surface. There is an increase in the amount of scale and the resistance to heat transfer. The fluid flow rate also increases the fouling resistance and the thickness of the scale layer.

Keywords: fouling, heat exchanger, thermal resistance, crystallization, potable water

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Authors: Deyadeen Ali Alshibani

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In the literature, the multi-armed bandit problem as a statistical decision model of an agent trying to optimize his decisions while improving his information at the same time. There are several different algorithms models and their applications on this problem. In this paper, we evaluate the Regret-regression through comparing with Q-learning method. A simulation on determination of optimal treatment regime is presented in detail.

Keywords: optimal, bandit problem, optimization, dynamic programming

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Authors: Camila Lemos Pinto, Juliana Alves Carneiro, Patrícia Borges Botelho, João Felipe Mota

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Sarcopenia, a syndrome characterized by progressive and generalized loss of skeletal muscle mass and strength, currently affects over 50 million people and increases the risk of adverse outcomes such as physical disability, poor quality of life and death. The aim of this study was to examine the efficacy of creatine supplementation associated with resistance training on muscle mass in the elderly. A 12-week, double blind, randomized, parallel group, placebo controlled trial was conducted. Participants were randomly allocated into one of the following groups: placebo with resistance training (PL+RT, n=14) and creatine supplementation with resistance training (CR + RT, n=13). The subjects from CR+RT group received 5 g/day of creatine monohydrate and the subjects from the PL+RT group were given the same dose of maltodextrin. Participants were instructed to ingest the supplement on non-training days immediately after lunch and on training days immediately after resistance training sessions dissolved in a beverage comprising 100 g of maltodextrin lemon flavored. Participants of both groups undertook a supervised exercise training program for 12 weeks (3 times per week). The subjects were assessed at baseline and after 12 weeks. The primary outcome was muscle mass, assessed by dual energy X-ray absorptiometry (DXA). The secondary outcome included diagnose participants with one of the three stages of sarcopenia (presarcopenia, sarcopenia and severe sarcopenia) by skeletal muscle mass index (SMI), handgrip strength and gait speed. CR+RT group had a significant increase in SMI and muscle (p<0.0001), a significant decrease in android and gynoid fat (p = 0.028 and p=0.035, respectively) and a tendency of decreasing in body fat (p=0.053) after the intervention. PL+RT only had a significant increase in SMI (p=0.007). The main finding of this clinical trial indicated that creatine supplementation combined with resistance training was capable of increasing muscle mass in our elderly cohort (p=0.02). In addition, the number of subjects diagnosed with one of the three stages of sarcopenia at baseline decreased in the creatine supplemented group in comparison with the placebo group (CR+RT, n=-3; PL+RT, n=0). In summary, 12 weeks of creatine supplementation associated with resistance training resulted in increases in muscle mass. This is the first research with elderly of both sexes that show the same increase in muscle mass with a minor quantity of creatine supplementation in a short period. Future long-term research should investigate the effects of these interventions in sarcopenic elderly.

Keywords: creatine, dietetic supplement, elderly, resistance training

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Authors: Tsuneyuki Namekata, Yoko Namekata

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It is known that the mean investment evolves from a very low initial value to some high level in the Continuous Prisoner's Dilemma. We examine how the cooperation level evolves from a low initial level to a high level in our Demographic Multi-level Donor-Recipient situation. In the Multi-level Donor-Recipient game, one player is selected as a Donor and the other as a Recipient randomly. The Donor has multiple cooperative moves and one defective move. A cooperative move means the Donor pays some cost for the Recipient to receive some benefit. The more cooperative move the Donor takes, the higher cost the Donor pays and the higher benefit the Recipient receives. The defective move has no effect on them. Two consecutive Multi-level Donor-Recipient games, one as a Donor and the other as a Recipient, can be viewed as a discrete version of the Continuous Prisoner's Dilemma. In the Demographic Multi-level Donor-Recipient game, players are initially distributed spatially. In each period, players play multiple Multi-level Donor-Recipient games against other players. He leaves offspring if possible and dies because of negative accumulated payoff of him or his lifespan. Cooperative moves are necessary for the survival of the whole population. There is only a low level of cooperative move besides the defective move initially available in strategies of players. A player may modify and expand his strategy by his recent experiences or practices. We distinguish several types of a player about modification and expansion. We show, by Agent-Based Simulation, that introducing only the modification increases the emergence rate of cooperation and introducing both the modification and the expansion further increases it and a high level of cooperation does emerge in our Demographic Multi-level Donor-Recipient Game.

Keywords: agent-based simulation, donor-recipient game, emergence of cooperation, spatial structure, TFT, TF2T

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Authors: Abdulmagid A. Khattabi, Abdul Fatah M. Emhamed

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The steel alloy Introduced after becoming carbon-steel does not meet the requirements of engineering industry; and it cannot be obtained tensile strength from carbon-steel higher than (700MPa), the low alloy steel enters in a lot of heavy engineering equipment parts, molds, agricultural equipment and other industry. In addition, that may be exposed to in-service failure, which may require returned to work, to do the repairs or maintenance by one of the welding methods available. The ability of steel weld determined through palpation of the cracks, which can reduce by many ways. These ways are often expensive and difficult to implement, perhaps the control to choose the type of electrode welding user is one of the easiest and least expensive applications. It has been welding the steel low alloys high resistance by manual metal arc (MMA), and by using a set of welding electrodes which varying in chemical composition and in their prices as well and test their effect on tensile strength. Results showed that using the poles of welding, which have a high proportion of iron powder and low hydrogen. The Tensile resistance is (484MPa) and the weld joint efficiency was (56.9%), but when (OK 47.04) electrode was used the tensile strength increased to (720MPa) and the weld joint efficiency to (84.7%). Using the cheapest electrode (OK 45.00) the weld joint efficiency did not exceed (24.2%), but when using the most expensive electrode (OK 91.28) the weld joint efficiency is (38.1%).

Keywords: steel low alloys high resistance, electrodes welding, tensile test

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Authors: Omneya M. Helmy, Mona T. Kashef

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Aminoglycosides are used in treating a wide range of infections caused by both Gram-negative and Gram positive bacteria. The presence of 16S rRNA methyl transferases (16S-RMTase) is among the newly discovered resistance mechanisms that confer high resistance to clinically useful aminoglycosides. Cephalosporins are the most commonly used antimicrobials in Egypt; therefore, this study was conducted to determine the isolation frequency of 16S rRNA methyl transferases among third generation cephalosporin-resistant clinical isolates in Egypt. One hundred and twenty three cephalosporin resistant Gram-negative clinical isolates were screened for aminoglycoside resistance by the Kirby Bauer disk diffusion method and tested for possible production of 16S-RMTase. PCR testing and sequencing were used to confirm the presence of 16S-RMTase and the associated antimicrobial resistance determinants, as well as the genetic region surrounding the armA gene. Out of 123 isolates, 66 (53.66%) were resistant to at least one aminoglycoside antibiotic. Only one Escherichia coli isolate (E9ECMO) which was totally resistant to all tested aminoglycosides, was confirmed to have the armA gene in association with blaTEM-1, blaCTX-M-15, blaCTX-M-14 and aac(6)-Ib genes. The armA gene was found to be carried on a large A/C plasmid. Genetic mapping of the armA surrounding region revealed, for the first time, the association of armA with aac(6)-Ib on the same transposon. In Conclusion, the isolation frequency of 16S-RMTase was low among the tested cephalosporin-resistant clinical samples. However, a novel composite transposon has been detected conferring high-level aminoglycosides resistance.

Keywords: aminoglcosides, armA gene, β lactmases, 16S rRNA methyl transferases

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Authors: Qian Qiao, Tongjin Xiao, Hongtu He, Jiaxin Yu

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This study is focused on the synergetic effects of water and sulfur dioxide treatments (SO₂ treatments) on the mechanochemical wear of SLS glass. It is found that the wear behavior of SLS glass in humid air is very sensitive to the water and SO₂ treatment environments based on the wear test using a ball-on-flat reciprocation tribometer. When SLS glass is treated with SO₂-without, the presence of water, the wear resistance of SLS glass in humid air becomes significantly higher compared to the pristine glass. However, when SLS glass is treated with SO₂ with the presence of water, the wear resistance of SLS glass decreases remarkably with increasing in the relative humidity (RH) from 0% to 90%. Further analyses indicate that when sodium ions are leached out of SLS glass surface via the water and SO₂ treatments, the mechanochemical properties of SLS glass surface become different depending on the RH. At lower humidity, the nano hardness of the Na⁺-leached surface is higher, and it can contribute to the enhanced wear resistance of SLS glass. In contrast, at higher humidity conditions, the SLS glass surface is more hydrophilic, and substantial wear debris can be found inside the wear track of SLS glass. Those phenomena suggest that adhesive wear and abrasive wear dominate the wear mechanism of SLS glass in humid air, causing the decreased wear resistance of SLS glass with increasing the RH. These results may not only provide a deep understanding of the wear mechanism of SLS glass but also helpful for operation process of functional and engineering glasses.

Keywords: soda lime silicate glass, wear, water, SO₂

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Authors: Jean Berger, Nassirou Lo, Martin Noel

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Perfectly suited for natural or man-made emergency and disaster management situations such as flood, earthquakes, tornadoes, or tsunami, multi-target search path planning for a team of rescue agents is known to be computationally hard, and most techniques developed so far come short to successfully estimate optimality gap. A novel mixed-integer linear programming (MIP) formulation is proposed to optimally solve the multi-target multi-agent discrete search and rescue (SAR) path planning problem. Aimed at maximizing cumulative probability of successful target detection, it captures anticipated feedback information associated with possible observation outcomes resulting from projected path execution, while modeling agent discrete actions over all possible moving directions. Problem modeling further takes advantage of network representation to encompass decision variables, expedite compact constraint specification, and lead to substantial problem-solving speed-up. The proposed MIP approach uses CPLEX optimization machinery, efficiently computing near-optimal solutions for practical size problems, while giving a robust upper bound obtained from Lagrangean integrality constraint relaxation. Should eventually a target be positively detected during plan execution, a new problem instance would simply be reformulated from the current state, and then solved over the next decision cycle. A computational experiment shows the feasibility and the value of the proposed approach.

Keywords: search path planning, search and rescue, multi-agent, mixed-integer linear programming, optimization

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Authors: G. Gokceli, O. Eksik, E. Ozkan Zayim, N. Karatepe

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Alternative electrode materials for optoelectronic devices have been widely investigated in recent years. Since indium tin oxide (ITO) is the most preferred transparent conductive electrode, producing ITO films by simple and cost-effective solution-based techniques with enhanced optical and electrical properties has great importance. In this study, single- and multi-walled carbon nanotubes (SWCNT and MWCNT) incorporated into the ITO structure to increase electrical conductivity, mechanical strength, and chemical stability. Carbon nanotubes (CNTs) were firstly functionalized by acid treatment (HNO₃:H₂SO₄), and the thermal resistance of CNTs after functionalization was determined by thermogravimetric analysis (TGA). Thin films were then prepared by spin coating technique and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), four-point probe measurement system and UV-Vis spectrophotometer. The effects of process parameters were compared for ITO, MWCNT-ITO, and SWCNT-ITO films. Two factors including CNT concentration and annealing temperature were considered. The UV-Vis measurements demonstrated that the transmittance of ITO films was 83.58% at 550 nm, which was decreased depending on the concentration of CNT dopant. On the other hand, both CNT dopants provided an enhancement in the crystalline structure and electrical conductivity. Due to compatible diameter and better dispersibility of SWCNTs in the ITO solution, the best result in terms of electrical conductivity was obtained by SWCNT-ITO films with the 0.1 g/L SWCNT dopant concentration and heat-treatment at 550 °C for 1 hour.

Keywords: CNT incorporation, ITO electrode, spin coating, thin film

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Authors: Syed Asif Hassan, Tabrej Khan

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Multiple sclerosis (MS) is a chronic demyelinating autoimmune disorder, of the central nervous system (CNS). In the present scenario, the current therapies either do not halt the progression of the disease or have side effects which limit the usage of current Disease Modifying Therapies (DMTs) for a longer period of time. Therefore, keeping the current treatment failure schema, we are focusing on screening novel analogues of the available DMTs that specifically bind and inhibit the Sphingosine1-phosphate receptor1 (S1PR1) thereby hindering the lymphocyte propagation toward CNS. The novel drug-like analogs molecule will decrease the frequency of relapses (recurrence of the symptoms associated with MS) with higher efficacy and lower toxicity to human system. In this study, an integrated approach involving ligand-based virtual screening protocol (Ultrafast Shape Recognition with CREDO Atom Types (USRCAT)) to identify the non-toxic drug like analogs of the approved DMTs were employed. The potency of the drug-like analog molecules to cross the Blood Brain Barrier (BBB) was estimated. Besides, molecular docking and simulation using Auto Dock Vina 1.1.2 and GOLD 3.01 were performed using the X-ray crystal structure of Mtb LprG protein to calculate the affinity and specificity of the analogs with the given LprG protein. The docking results were further confirmed by DSX (DrugScore eXtented), a robust program to evaluate the binding energy of ligands bound to the ligand binding domain of the Mtb LprG lipoprotein. The ligand, which has a higher hypothetical affinity, also has greater negative value. Further, the non-specific ligands were screened out using the structural filter proposed by Baell and Holloway. Based on the USRCAT, Lipinski’s values, toxicity and BBB analysis, the drug-like analogs of fingolimod and BG-12 showed that RTL and CHEMBL1771640, respectively are non-toxic and permeable to BBB. The successful docking and DSX analysis showed that RTL and CHEMBL1771640 could bind to the binding pocket of S1PR1 receptor protein of human with greater affinity than as compared to their parent compound (Fingolimod). In this study, we also found that all the drug-like analogs of the standard MS drugs passed the Bell and Holloway filter.

Keywords: antagonist, binding affinity, chemotherapeutics, drug-like, multiple sclerosis, S1PR1 receptor protein

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Authors: Okba Belahssen, Said Benramache

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This paper presents wear behavior of the plasma-nitrided 20MnCr5 steel. Untreated and plasma nitrided samples were tested. The morphology was observed by scanning electron microscopy (SEM). The plasma nitriding behaviors of 20MnCr5 steel have been assessed by evaluating tribological properties and surface hardness by using a pin-on-disk wear machine and microhardness tester. Experimental results showed that the nitrides ε-Fe2−3N and γ′-Fe4N present in the white layer improve the wear resistance.

Keywords: plasma-nitriding, alloy 20mncr5, steel, friction, wear

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Authors: Chur Hee Lee, Ju Sik Kwak, Seung Wan Kim

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This paper deals about economics and control of optimal placement of multi-terminal HVDC in Korea. Currently, No.1 and 2 HVDC are installed in Jeju and Mainland, Dangjin Godeok HVDC starts operation in 2020. Jeju No.3 HVDC also starts operation in 2022. HVDC systems in Korea are expanding. Also, super grid projects with China, Japan, and Russia are under consideration. In this situation, it is necessary to study how to install optimal HVDC in Korea and how to control it. After initializing the Optical Polwer Flow (OPF) procudure using lossless economic dispatch, grobal iteration will be set. And then, this will be formed as the Lagrangian function and linearizied. We will also analyze the advantages and disadvantages of each operation mode for optimal operating conditions of voltage and current complex HVDC in Korea.

Keywords: economics, HVDC, multi terminal, optimal

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Authors: Xiao Yihong, Yu Kexin, Burra Venkata Durga Kumar

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With the accelerating process of urbanization, the problem of urban road congestion is becoming more and more serious. Intelligent transportation system combining distributed and artificial intelligence has become a research hotspot. As the core development direction of the intelligent transportation system, Cooperative Intelligent Transportation System (C-ITS) integrates advanced information technology and communication methods and realizes the integration of humans, vehicle, roadside infrastructure, and other elements through the multi-agent distributed system. By analyzing the system architecture and technical characteristics of C-ITS, the report proposes a distributed multi-agent C-ITS. The system consists of Roadside Sub-system, Vehicle Sub-system, and Personal Sub-system. At the same time, we explore the scalability of the C-ITS and put forward incorporating local rewards in the centralized training decentralized execution paradigm, hoping to add a scalable value decomposition method. In addition, we also suggest introducing blockchain to improve the safety of the traffic information transmission process. The system is expected to improve vehicle capacity and traffic safety.

Keywords: distributed system, artificial intelligence, multi-agent, cooperative intelligent transportation system

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Authors: Kianoosh Samimi, Siham Kamali-Bernard, Ali Akbar Maghsoudi

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This paper aims to contribute to the characterization and the understanding of fresh state, compressive strength and chloride penetration tendency of high strength self-compacting concretes (HSSCCs) where Portland cement type II is partially substituted by 10% and 15% of natural pumice and zeolite. First, five concrete mixtures with a control mixture without any pozzolan are prepared and tested in both fresh and hardened states. Then, resistance to chloride penetration for all formulation is investigated in non-steady state and steady state by measurement of chloride penetration and diffusion coefficient. In non-steady state, the correlation between initial current and chloride penetration with diffusion coefficient is studied. Moreover, the relationship between diffusion coefficient in non-steady state and electrical resistivity is determined. The concentration of free chloride ions is also measured in steady state. Finally, chloride penetration for all formulation is studied in immersion and tidal condition. The result shows that, the resistance to chloride penetration for HSSCC in immersion and tidal condition increases by incorporating pumice and zeolite. However, concrete with zeolite displays a better resistance. This paper shows that the HSSCC with 15% pumice and 10% zeolite is suitable in fresh, hardened, and durability characteristics.

Keywords: Chloride penetration, immersion, pumice, HSSCC, tidal, zeolite

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Authors: Huzaifa Bilal

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Russian wheat aphid (Diuraphis noxia, Kurdjumov) is considered an economically important wheat (Triticum aestivum L.) pest worldwide and in South Africa. The RWA damages wheat plants and reduces annual yields by more than 10%. Even though pest management by pesticides and resistance breeding is an attractive option, chemicals can cause harm to the environment. Furthermore, the evolution of resistance-breaking aphid biotypes has out-paced the release of resistant cultivars. An alternative strategy to reduce the impact of aphid damage on plants, such as priming, which sensitizes plants to respond effectively to subsequent attacks, is necessary. In this study, wheat plants at the seedling and flag leaf stages were primed by salicylic acid and isolate representative of two races of the leaf rust pathogen Puccinia triticina Eriks. (Pt), before RWA (South African RWA biotypes 1 and 4) infestation. Randomized complete block design experiments were conducted in the greenhouse to study plant-pest interaction in primed and non-primed plants. Analysis of induced aphid damage indicated salicylic acid differentially primed wheat cultivars for increased resistance to the RWASA biotypes. At the seedling stage, all cultivars were primed for enhanced resistance to RWASA1, while at the flag leaf stage, only PAN 3111, SST 356 and Makalote were primed for increased resistance. The Puccinia triticina efficaciously primed wheat cultivars for excellent resistance to RWASA1 at the seedling and flag leaf stages. However, Pt failed to enhance the four Lesotho cultivars' resistance to RWASA4 at the seedling stage and PAN 3118 at the flag leaf stage. The induced responses at the seedling and flag leaf stages were positively correlated in all the treatments. Primed plants induced high activity of antioxidant enzymes like peroxidase, ascorbate peroxidase and superoxide dismutase. High antioxidant activity indicates activation of resistant responses in primed plants (primed by salicylic acid and Puccina triticina). Isolates of avirulent Pt races can be a worthy priming agent for improved resistance to RWA infestation. Further confirmation of the priming effects needs to be evaluated at the field trials to investigate its application efficiency.

Keywords: Russian wheat aphis, salicylic acid, puccina triticina, priming

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Authors: Reynaldo Esquivel, Pedro Hernandez, Aaron Martinez-Higareda, Sergio Tena-Cano, Enrique Alvarez-Ramos, Armando Lucero-Acuna

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Stimuli-responsive nanomaterials play an essential role in loading, transporting and well-distribution of anti-cancer compounds in the cellular surroundings. The outstanding properties as the Lower Critical Solution Temperature (LCST), hydrolytic cleavage and protonation/deprotonation cycle, govern the release and delivery mechanisms of payloads. In this contribution, we experimentally determine the load efficiency and release of antineoplastic Vincristine Sulfate into PNIPAM-Interpenetrated-Chitosan (PIntC) nanoparticles. Structural analysis was performed by Fourier Transform Infrared Spectroscopy (FT-IR) and Proton Nuclear Magnetic Resonance (1HNMR). ζ-Potential (ζ) and Hydrodynamic diameter (DH) measurements were monitored by Electrophoretic Mobility (EM) and Dynamic Light scattering (DLS) respectively. Mathematical analysis of the release pharmacokinetics reveals a three-phase model above LCST, while a monophasic of Vincristine release model was observed at 32 °C. Cytotoxic essays reveal a noticeable enhancement of Vincristine effectiveness at low drug concentration on HeLa cervix cancer and MDA-MB-231 breast cancer.

Keywords: nanoparticles, vincristine, drug delivery, PNIPAM

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Authors: Gyumin Hwang, Jihong Lee

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This paper studied the CSS-based indoor localization system which is easy to implement, inexpensive to compose the systems, additionally CSS-based indoor localization system covers larger area than other system. However, this system has problem which is affected by reflected distance data. This problem in localization is caused by the multi-path effect. Error caused by multi-path is difficult to be corrected because the indoor environment cannot be described. In this paper, in order to solve the problem by multi-path, we have supplemented the localization system by using pattern matching method based on extended database. Thereby, this method improves precision of estimated. Also this method is verified by experiments in gymnasium. Database was constructed by 1 m intervals, and 16 sample data were collected from random position inside the region of DB points. As a result, this paper shows higher accuracy than existing method through graph and table.

Keywords: chirp spread spectrum, indoor localization, pattern-matching, time of arrival, multi-path, mahalanobis distance, reception rate, simultaneous localization and mapping, laser range finder

Procedia PDF Downloads 248

Authors: F. Ghasim-akbari, A. M. Hadian, A. M. Aminazad

Abstract:

Fluid transmission pipes made of aluminum are widely use in petrochemical industries. For many applications they have to be brazed to each other. The brazed joints, in many cases, are encountered with corrosive medias. This paper reports a part of a work to investigate the corrosion behavior of brazed Al6061 using Al4047 as filler metal with and without the use of flux to discover the effect of different brazing atmospheres. The samples brazed under air, vacuum, argon, and hydrogen atmospheres. The interfacial area of the joints was examined to ensure being free of any defects. The sides of each test piece were covered with insulator and the surface of the joint was encountered to polarization test. The results revealed a significant difference of corrosion resistance. The samples that brazed under argon and hydrogen atmospheres had better corrosion resistance than other samples. Microstructure of the corroded joints revealed that the amount of the filler metal is a critical parameter on corrosion resistance of the joints.

Keywords: brazing, corrosion behavior, Al6061, polarization

Procedia PDF Downloads 499

Authors: Ruitao Li, Zhili Dong, Nay Win Khun, Khiam Aik Khor

Abstract:

In this study, microstructure and sintering mechanism as well as wear resistance properties of Ti/Al-Cr-Fe metal matrix composites (MMCs) fabricated by spark plasma sintering (SPS) with Ti as matrix and Al-Cr-Fe as reinforcement were investigated. Phases and microstructure of the sintered samples were analyzed using X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). Wear resistance properties were tested by ball-on-disk method. An Al3Ti ring forms around each Al-Cr-Fe particle as the bonding layer between Ti and Al-Cr-Fe particles. The Al content in Al-Cr-Fe particles experiences a decrease from 70 at.% to 60 at.% in the sintering process. And these particles consist of quasicrystalline icosahedral AlCrFe and quasicrystal approximants γ-brass Al8(Cr,Fe)5 and Al9(Cr,Fe)4 in the sintered compact. The addition of Al-Cr-Fe particles into the Ti matrix can improve the microhardness by about 40% and the wear resistance is improved by more than 50% due to the increase in the microhardness and the change of wear mechanism.

Keywords: metal matrix composites, spark plasma sintering, phase transformation, wear

Procedia PDF Downloads 427

Authors: Hui Hsin Huang

Abstract:

The downstream manufactures will order their materials from different upstream suppliers to maintain a certain level of the demand. This paper proposes a bivariate model to portray this phenomenon of material demand. We use empirical data to estimate the parameters of model and evaluate the RMSD of model calibration. The results show that the model has better fitness.

Keywords: recency, ordering time, materials demand quantity, multi-source ordering

Procedia PDF Downloads 541

Authors: Jiwoo Park, Junseok Yoon, Jeong Kim, Beomsoo Kang

Abstract:

Multi-Point Stretch Forming (MPSF) process is suitable for flexible manufacturing, and it has several advantages including that it could be applied to various forming such as sheet metal forming, single curved surface forming and double curved one. In this study, a systematic numerical simulation was carried out for atypical double curved surface forming using the multiple die stretch forming process. In this simulation, urethane pads were defined based on hyper-elastic material model as a cushion for the smooth forming surface. The deformation behaviour on elastic recovery was also investigated to consider the exact result after the last forming process, and then the experiment was also carried out to confirm the formability of this forming process. By comparing the simulation and experiment results, the suitability of the multiple die stretch forming process for the atypical double curved surface was verified. Consequently, it is confirmed that the multi-point stretch forming process has the capability and feasibility of being used to manufacture the double curved surfaces of sheet metal.

Keywords: multi-point stretch forming, double curved surface, numerical simulation, manufacturing

Procedia PDF Downloads 484

Authors: Fatna Benmessaoud, Mohammed Cheikh, Vencent Velay, Vanessa Vidal, Farhad Rezai-Aria, Christine Boher

Abstract:

Ti-6Al-4V titanium alloy is one of the most widely used materials in aeronautical and aerospace industries. Because of its high specific strength, good fatigue, and corrosion resistance, this alloy is very suitable for moderate temperature applications. At room temperature, Ti-6Al-4V mechanical behavior is generally controlled by the behavior of alpha phase (beta phase percent is less than 8%). The plastic strain of this phase notably based on crystallographic slip can be hindered by various obstacles and mechanisms (crystal lattice friction, sessile dislocations, strengthening by solute atoms and grain boundaries…). The grains aspect of alpha phase (its morphology and texture) and the nature of its crystallographic lattice (which is hexagonal compact) give to plastic strain heterogeneous, discontinuous and anisotropic characteristics at the local scale. The aim of this work is to develop a multi-scale model for Ti-6Al-4V mechanical behavior using crystal plasticity approach; this multi-scale model is used then to investigate grains size, dispersion of grains size, crystallographic texture and slip systems activation effects on Ti-6Al-4V mechanical behavior under monotone quasi-static loading. Nine representative elementary volume (REV) are built for taking into account the physical elements (grains size, dispersion and crystallographic) mentioned above, then boundary conditions of tension test are applied. Finally, simulation of the mechanical behavior of Ti-6Al-4V and study of slip systems activation in alpha phase is reported. The results show that the macroscopic mechanical behavior of Ti-6Al-4V is strongly linked to the active slip systems family (prismatic, basal or pyramidal). The crystallographic texture determines which family of slip systems can be activated; therefore it gives to the plastic strain a heterogeneous character thus an anisotropic macroscopic mechanical behavior of Ti-6Al-4V alloy modeled. The grains size influences also on mechanical proprieties of Ti-6Al-4V, especially on the yield stress; by decreasing of the grain size, the yield strength increases. Finally, the grains' distribution which characterizes the morphology aspect (homogeneous or heterogeneous) gives to the deformation fields distribution enough heterogeneity because the crystallographic slip is easier in large grains compared to small grains, which generates a localization of plastic deformation in certain areas and a concentration of stresses in others.

Keywords: multi-scale modeling, Ti-6Al-4V alloy, crystal plasticity, grains size, crystallographic texture

Procedia PDF Downloads 159

Authors: A. Zanj, F. He

Abstract:

In the current paper, a domain independent conduction model compatible for multi-physical system dynamic investigations is suggested. By means of a port-based approach, a classical nonlinear conduction model containing physical states is first represented. A compatible discrete configuration of the thermal domain in line with the elastic domain is then generated through the enhancement of the configuration of the conventional thermal element. The presented simulation results of a sample structure indicate that the suggested conductive model can cover a wide range of dynamic behavior of the thermal domain.

Keywords: multi-physical domain, conduction model, port based modeling, dynamic interaction, physical modeling

Procedia PDF Downloads 278