Search results for: tamper resistance

Authors: S. K. Hashemi, M. A. Bradford, H. R. Valipour

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The Recent collapse of bridges has raised the awareness about safety and robustness of bridges subjected to extreme loading scenarios such as intentional/unintentional blast loads. The air blast generated by the explosion of bombs or fuel tankers leads to high-magnitude short-duration loading scenarios that can cause severe structural damage and loss of critical structural members. Hence, more attentions need to put towards bridge structures to develop guidelines to increase the resistance of such structures against the probable blast. Recent advancements in numerical methods have brought about the viable and cost effective facilities to simulate complicated blast scenarios and subsequently provide useful reference for safeguarding design of critical infrastructures. In the previous studies common bridge responses to blast load, the traffic load is sometimes not included in the analysis. Including traffic load will increase the axial compression in bridge piers especially when the axial load is relatively small. Traffic load also can reduce the uplift of girders and deck when the bridge experiences under deck explosion. For more complicated structures like cable-stayed or suspension bridges, however, the effect of traffic loads can be completely different. The tension in the cables increase and progressive collapse is likely to happen while traffic loads exist. Accordingly, this study is an attempt to simulate the effect of traffic load cases on the maximum local and global response of an entire cable-stayed bridge subjected to blast loadings using LS-DYNA explicit finite element code. The blast loads ranged from small to large explosion placed at different positions above the deck. Furthermore, the variation of the traffic load factor in the load combination and its effect on the dynamic response of the bridge under blast load is investigated.

Keywords: blast, cable-stayed bridge, LS-DYNA, numerical, traffic load

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Authors: Adeline Fontvieille, Hugo Parent-Roberge, Marie-France Langlois, Tamas Fulop, Michel Pavic, Eleonor Riesco

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Introduction: Total lean body mass is reduced during cancer treatment. This loss is called cancer cachexia and is accompanied by a progressive loss of fat mass. In older adults, these body composition changes can have a larger impact on metabolic health, physical autonomy, and cancer survival. Although currently untreatable, exercise training could reduce these effects. Hence, the objective of this pilot study is to investigate if 12 weeks of exercise training during cancer treatment can mitigate the loss of muscle mass and fat mass in older adults. Methods: A total of 40 older adults (65-80 years) with an ongoing treatment for a curable cancer are currently recruited and randomised in two groups: 1) Combined training (EX, n=20) and 2) Control group (CON, n=20). All variables are measured before and after 12 weeks of intervention: Anthropometry (weight, height, body mass index), body composition (total fat mass, visceral adipose tissue, total and appendicular muscle mass; DXA), metabolic profile (HDL-C and LDL-C, triglycerides, glucose and insulin levels). Results: Preliminary analyses revealed no impact of exercise training on appendicular muscle mass (p=0,31) and fat mass (p=0,31). Furthermore, total body weight, waist circumference, HDL-cholesterol, LDL-cholesterol, glucose and insulin levels remained unchanged (all p ≥ 0.79) after 12 weeks of training. However, statistical analyses revealed that triglyceride levels slightly increased (p=0.03), irrespective of the group. Conclusion: Preliminary analyses did not reveal any impact of aerobic and resistance exercise training on body composition in oncogeriatric patients. Furthermore, exercise training seems not efficient to prevent the cancer treatment-related triglyceride levels increase.

Keywords: muscle mass, fat mass, metabolic profile, combined training, aging, cancer

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Authors: S. Koul, Joshua Adedamola

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Currently, the global concerning fact about electromagnetic pollution (EMP) is that it not only adversely affects human health but rather projects the malfunctioning of sensitive equipment both locally and at a global level. The market offers many incumbent technologies to solve the issues, but still, a processable sustainable material solution with acceptable limits for GHG emission is still at an exploratory stage. The present work offers a sustainable material solution with a wide range of processability in terms of a polymeric resin matrix and shielding operational efficiency across the electromagnetic spectrum, covering both ionizing and non-ionizing electromagnetic radiations. The present work offers an in-situ synthesized conducting polyaniline (PANI) in the presence of the hybrid dual dopant system with tuned conductivity and high shielding efficiency between 89 to 92 decibels, depending upon the EMI frequency range. The conductive polymer synthesized in the presence of a hybrid dual dopant system via the in-situ emulsion polymerization method offers a higher surface resistance of 1.0 ohms/cm with thermal stability up to 2450C in their powder form. This conductive polymer with a hybrid dual dopant system was used as a filler material with different polymeric thermoplastic resin systems for the preparation of conductive composites. Intrinsically Conductive polymeric (ICP) composites based on hybrid dual dopant systems were prepared using melt blending, extrusion, and finally by, compression molding processing techniques. ICP composites with hybrid dual dopant systems offered good mechanical, thermal, structural, weathering, and stable surface resistivity properties over a period of time. The preliminary shielding behavior for ICP composites between frequency levels of 10 GHz to 24GHZ offered a shielding efficiency of more than 90 dB.

Keywords: ICP, dopant, EMI, shielding

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Authors: K. S. Sivakumaran, T. Thanga, B. Halabieh

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The end panels of a large rectangular industrial duct, which experience significant internal pressures, also experience considerable transverse shear due to transfer of gravity loads to the supports. The current design practice of such thin plate panels for shear load is based on methods used for the design of plate girder webs. The structural arrangements, the loadings and the resulting behavior associated with the industrial duct end panels are, however, significantly different than those of the web of a plate girder. The large aspect ratio of the end panels gives rise to multiple bands of tension fields, whereas the plate girder web design is based on one tension field. In addition to shear, the industrial end panels are subjected to internal pressure which in turn produces significant membrane action. This paper reports a study which was undertaken to review the current industrial analysis and design methods and to propose a comprehensive method of designing industrial duct end panels for shear resistance. In this investigation, a nonlinear finite element model was developed to simulate the behavior of industrial duct end panel subjected to transverse shear and internal pressures. The model considered the geometric imperfections and constitutive relations for steels. Six scale independent dimensionless parameters that govern the behavior of such end panel were identified and were then used in an extensive parametric study. It was concluded that the plate slenderness dominates the shear strength of stockier end panels, and whereas, the aspect ratio and plate slenderness influence the shear strength of slender end panels. Based on these studies, this paper proposes design aids for estimating the shear strength of rectangular duct end panels.

Keywords: thin plate, transverse shear, tension field, finite element analysis, parametric study, design

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Authors: Koustav Pal, Indranil Das

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In recent times, perovskite and double perovskite (DP) systems attracts lot of interest as they provide a rich material platform for studying emergent functionalities like near-room-temperature ferromagnetic (FM) insulators, exchange bias (EB), magnetocaloric effects, colossal magnetoresistance, anisotropy, etc. These interesting phenomena emerge because of complex couplings between spin, charge, orbital, and lattice degrees of freedom in these systems. Various magnetic phenomena such as exchange bias, spin glass, memory effect, colossal magneto-resistance, etc. can be modified and controlled through antisite (B-site) disorder or controlling oxygen concentration of the material. By controlling oxygen concentration in SrFe0.5Co0.5O3 – δ (SFCO) (δ ∼ 0.3), we achieve intrinsic exchange bias effect with a large exchange bias field (∼1.482 Tesla) and giant coercive field (∼1.454 Tesla). Now we modified the B-site by introducing 10% iridium in the system. This modification give rise to the exchange bias field as high as 1.865 tesla and coercive field 1.863 tesla. Our work aims to investigate the effect of oxygen deficiency and B-site effect on exchange bias in oxide materials for potential technological applications. Structural characterization techniques including X-ray diffraction, scanning tunneling microscopy, and transmission electron microscopy were utilized to determine crystal structure and particle size. X-ray photoelectron spectroscopy was used to identify valence states of the ions. Magnetic analysis revealed that oxygen deficiency resulted in a large exchange bias due to a significant number of ionic mixtures. Iridium doping was found to break interaction paths, resulting in various antiferromagnetic and ferromagnetic surfaces that enhance exchange bias.

Keywords: coercive field, disorder, exchange bias, spin glass

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Authors: S. Redjala, N. Ait Hocine, M. Gratton, N. Poirot, R. Ferhoum, S. Azem

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Polycarbonate (PC) is a promising polymer with high transparency in the range of the visible spectrum and is used in various fields, for example medical, electronic, automotive. Its low weight, chemical inertia, high impact resistance and relatively low cost are of major importance. In recent decades, some materials such as metals and ceramics have been replaced by polymers because of their superior advantages. However, some characteristics of the polymers are highly modified under the effect of ultraviolet (UV) radiation and temperature. The changes induced in the material by such aging depend on the exposure time, the wavelength of the UV radiation and the temperature level. The UV energy is sufficient to break the chemical bonds leading to a cleavage of the molecular chains. This causes changes in the mechanical, thermal, optical and morphological properties of the material. The present work is focused on the study of the effects of aging under ultraviolet (UV) radiation and under different temperature values on the physical-chemical and mechanical properties of a PC. Thus, various investigations, such as FTIR and XRD analyses, SEM and optical microscopy observations, micro-hardness measurements and monotonic and cyclic tensile tests, were carried out on the PC in the initial state and after aging. Results have shown the impact of aging on the properties of the PC studied. In fact, the MEB highlighted changes in the superficial morphology of the material by the presence of cracks and material de-bonding in the form of debris. The FTIR spectra reveal an attenuation of the peaks like the hydroxyl (OH) groups located at 3520 cm-1. The XRD lines shift towards a larger angle, reaching a maximum of 3°. In addition, Vickers micro-hardness measurements show that aging affects the surface and the core of the material, which results in different mechanical behaviours under monotonic and cyclic tensile tests. This study pointed out effects of aging on the macroscopic properties of the PC studied, in relationship with its microstructural changes.

Keywords: mechanical properties, physical-chemical properties, polycarbonate, UV aging, temperature aging

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Authors: Yazeed Al-Sheikh

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Pregnancy represents a risk factor in the occurrence of vulvovaginal candidiasis. To investigate the prevalence rate of vaginal carriage of Candida species in Saudi pregnant and non-pregnant women, high vaginal swab (HVS) specimens (707) were examined by direct microscopy (10% KOH and Giemsa staining) and parallel cultured on Sabouraud Dextrose Agar (SDA) as well as on “CHROM agar Candida” medium. As expected, Candida-positive cultures were frequently observed in pregnant-test group (24%) than in non-pregnant group (17%). The frequency of culture positive was correlated to pregnancy (P=0.047), parity (P=0.001), use of contraceptive (P=0.146), or antibiotics (P=0.128), and diabetic-patients (P < 0.0001). Out of 707 HVS examined specimens, 157 specimens were yeast-positive culture (22%) on Sabouraud Dextrose Agar or “CHROM agar Candida”. In comparison, the sensitivities of the direct 10% KOH and the Giemsa stain microscopic examination methods were 84% (132/157) and 95% (149/157) respectively but both with 100% specificity. As for the identity of recovered 157 yeast isolates, based on API 20C biotype carbohydrate assimilation, germ tube and chlamydospore formation, C. albicansand C. glabrata constitute 80.3 and 12.7% respectively. Rates of C. tropicalis, C. kefyr, C. famata or C. utilis were 2.6, 1.3, and 0.6% respectively. Sachromyces cerevisiae and Rhodotorula mucilaginosa yeasts were also encountered at a frequency of 1.3 and 0.6% respectively. Finally, among all recovered 157 yeast-isolates, strains resistant to ketoconazole were not detected, whereas 5% of the C. albicans and as high as 55% of the non-albicans yeast isolates (majority C. glabrata) showed resistance to fluconazole. Our findings may prove helpful for continuous determination of the existing vaginal candidiasis causative species during pregnancy, its lab-diagnosis and/or control and possible measures to minimize the incidence of the disease-associated pre-term delivery.

Keywords: vaginal candidiasis, Candida spp., pregnancy, risk factors, API 20C-yeast biotypes, giemsa stain, antifungal agents

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Authors: Nwafia Ifeyinwa Nkeiruka, Nwafia Walter Chukwuma

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Since the early 1980’s fungi have emerged as major causes of human diseases, especially among immunocompromised. The most commonly isolated yeast is Candida albicans and constitutes the 4th most common nosocomial BSI in humans. It is progressive and cumulative and become more complex over time.It can even lead to leaky gut syndrome that causes food and environmental allergies. It is worthy of note that all the available data on oral Candida risk factors in humans were documented essentially using data from studies conducted in other areas, hence there is need for comparative and complementary information from the South eastern part of Nigeria. Method: 200 subjects of all age groups of both sexes were randomly examined,by swabbing their palatine mucosa and dorsal tongue with sterile cotton wool,then cultured into Sabouraud dextrose agar plates supplemented with antibiotics and incubated aerobically at 37 degree for 48 hrs. Identification of Candida albicans was done by germ tubes tests, chlamydospores production on cornmeal agar supplemented with 1% Tween 80.Sugar and nitrogen assimilation test using API 20C Auxanogram and potassium nitrate agar. Results: Out of 30 samples that were positive for candida, 15 (50%) were candida albicans. Using the anova test (P < 0.05) this variation is significant (P = 0016). followed by C. dublinensis 3 (13%), C. tropicalis 3 (10%), C. pseudotropicalis 3 (10%), C, glabrata 2 (7%), C. parapsilosis 2 (7%) and lastly C. krusei 1 (3%).However, 53% of the patients were female while 47% were male. Among the HIV positive isolates.67% were HIV isolates not on drugs while 33% positives isolates were on drugs and the percentages of candida species in these patients were as follows C. albicans were 45% followed by C. glabrata and C.tropicalis which were 17% each, C.parapsilosis, C.dubliensis and C.pseudotropicalis were all 8% each. Conclusion: Oral Candidiasis is a marker of systemic diseases and in some cases, it may be the first clinical presentation. There is need for more intensive clinical and laboratory monitoring and possible early intervention to prevent the reoccurrence and resistance to treatment.

Keywords: oral cavity, Candida species, oral Candidiasis, risk factors

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Authors: Abbas Pourreza

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MicroRNAs (miRNAs) are small single-stranded non-coding RNAs. They are almost 18-25 nucleotides long and very conservative through evolution. They are involved in adjusting the expression of numerous genes due to the existence of a complementary region, generally in the 3' untranslated regions (UTR) of target genes, against particular mRNAs in the cell. Also, miRNAs have been proven to be involved in cell development, differentiation, proliferation, and apoptosis. More than 2000 miRNAs have been recognized in human cells, and these miRNAs adjust approximately one-third of all genes in human cells. Dysregulation of miRNA originated from abnormal DNA methylation patterns of the locus, cause to down-regulated or overexpression of miRNAs, and it may affect tumor formation or development of it. Breast cancer (BC) is the most commonly identified cancer, the most prevalent cancer (23%), and the second-leading (14%) mortality in all types of cancer in females. BC can be classified based on the status (+/−) of the hormone receptors, including estrogen receptor (ER), progesterone receptor (PR), and the Receptor tyrosine-protein kinase erbB-2 (ERBB2 or HER2). Currently, there are four main molecular subtypes of BC: luminal A, approximately 50–60 % of BCs; luminal B, 10–20 %; HER2 positive, 15–20 %, and 10–20 % considered Basal (triple-negative breast cancer (TNBC)) subtype. Aberrant expression of miR-145, miR-21, miR-10b, miR-125a, and miR-206 was detected by Stem-loop real-time RT-PCR in BC cases. Breast tumor formation and development may result from down-regulation of a tumor suppressor miRNA such as miR-145, miR-125a, and miR-206 and/or overexpression of an oncogenic miRNA such as miR-21 and miR-10b. MiR-125a, miR-206, miR-145, miR-21, and miR-10b are hugely predicted to be new tumor markers for the diagnosis and prognosis of BC. MiR-21 and miR-125a could play a part in the treatment of HER-2-positive breast cancer cells, while miR-145 and miR-206 could speed up the evolution of cure techniques for TNBC. To conclude, miRNAs will be presented as hopeful molecules to be used in the primary diagnosis, prognosis, and treatment of BC and battle as opposed to its developed drug resistance.

Keywords: breast cancer, HER2 positive, miRNA, TNBC

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Authors: Isabel Gouveia

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Antimicrobial textile materials may significantly reduce the risk of infections and because they are able to absorb substances from the skin and release therapeutic compounds to the skin, they can also find applications as complementary therapy of skin-diseases as part of standard management. Although functional textiles may be a promising area in skin disease/injury management, as part of standard management, few offer complementary treatment even though they are well known to reduce scratching and aiding emollient absorption, reducing infection, and alleviating pruritus. The reason for this may rely on the low quality of supporting evidence and negative effect that antimicrobial agents may exert on skin microbiome, as for example additional irritation of the vulnerable skin, and by causing resistant bacteria. Several antimicrobial agents have been tested in textiles: quaternary ammonium compounds, silver, polyhexamethylene-biguanides and triclosan have been used, with success. They have powerful bactericidal activity but the majority have a reduce spectrum of microbial inhibition and may cause skin irritation, ecotoxicity and bacteria resistance. Furthermore, the rising flow of strains resistant to last-resort antibiotics rekindles interest in alternative strategies. In this regard, new functional textiles incorporating highly specific antimicrobial agents towards pathogenic bacteria, are required. Recent research has been conducted on naturally occurring antimicrobials as novel alternatives to antibiotics. Conscious of this need our team firstly reported new approaches using L-cysteine and antimicrobial peptides (AMP). Briefly, we were able to develop different immobilization processes towards 6 Log Reduction against bacteria such as S. aureus and K. pneumoniae. Therefore, here we present several innovative antimicrobial textiles incorporating AMP and L-Cysteine which may open new avenues for the medical textiles market and biomaterials in general. Team references will be discussed as an overview and for comparison purposes in terms of potential therapeutic applications.

Keywords: Antimicrobials, Antimicrobial Textiles, Biomedical Textiles, Biomimetic surface functionalization

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Authors: Sadman Durlov, Aditya Ganesh-Ram, Hamidreza Hekmatjou, Md Najmus Salehin, Nora Shayesteh Ameri

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In the field of additive manufacturing, tungsten stands out for its exceptional resistance to high temperatures, making it an ideal candidate for use in extreme conditions. However, its inherent brittleness and vulnerability to thermal cracking pose significant challenges to its manufacturability. This study explores the microstructural evolution of tungsten processed through layer-wise rolling in laser powder bed fusion additive manufacturing, utilizing a comprehensive approach that combines advanced simulation techniques with empirical research. We aim to uncover the complex processes of plastic deformation and microstructural transformations, with a particular focus on the dynamics of grain size, boundary evolution, and phase distribution. Our methodology employs a combination of simulation and experimental data, allowing for a detailed comparison that elucidates the key mechanisms influencing microstructural alterations during the rolling process. This approach facilitates a deeper understanding of the material's behavior under additive manufacturing conditions, specifically in terms of deformation and recrystallization. The insights derived from this research not only deepen our theoretical knowledge but also provide actionable strategies for refining manufacturing parameters to improve the tungsten components' mechanical properties and functional performance. By integrating simulation with practical experimentation, this study significantly enhances the field of materials science, offering a robust framework for the development of durable materials suited for challenging operational environments. Our findings pave the way for optimizing additive manufacturing techniques and expanding the use of tungsten across various demanding sectors.

Keywords: additive manufacturing, layer wise rolling, refractory materials, in-situ microstructure modifications

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Authors: Hatem I. Mokhtar, Randa A. Abd-El-Salam, Ghada M. Hadad

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An improved nano-composite of self-doped polyaniline nanofibers and silica-coated magnetite nanoparticles were prepared and evaluated for suitability to magnetic dispersive micro solid-phase extraction. The work focused on optimization of the composite capacity to extract four fluoroquinolones (FQs) antibiotics, ciprofloxacin, enrofloxacin, danofloxacin, and difloxacin from water and improvement of composite stability towards acid and atmospheric degradation. Self-doped polyaniline nanofibers were prepared by oxidative co-polymerization of aniline with anthranilic acid. Magnetite nanopariticles were prepared by alkaline co-precipitation and coated with silica by silicate hydrolysis on magnetite nanoparticles surface at pH 6.5. The composite was formed by self-assembly by mixing self-doped polyaniline nanofibers with silica-coated magnetite nanoparticles dispersions in ethanol. The composite structure was confirmed by transmission electron microscopy (TEM). Self-doped polyaniline nanofibers and magnetite chemical structures were confirmed by FT-IR while silica coating of the magnetite was confirmed by Energy Dispersion X-ray Spectroscopy (EDS). Improved stability of the composite magnetic component was evidenced by resistance to degrade in 2N HCl solution. The adsorption capacity of self-doped polyaniline nanofibers based composite was higher than previously reported corresponding composite prepared from polyaniline nanofibers instead of self-doped polyaniline nanofibers. Adsorption-pH profile for the studied FQs on the prepared composite revealed that the best pH for adsorption was in range of 6.5 to 7. Best extraction recovery values were obtained at pH 7 using phosphate buffer. The best solvent for FQs desorption was found to be 0.1N HCl in methanol:water (8:2; v/v) mixture. 20 mL of Spiked water sample with studied FQs were preconcentrated using 4.8 mg of composite and resulting extracts were analysed by HPLC-UV method. The prepared composite represented a suitable adsorbent phase for magnetic dispersive micro-solid phase application.

Keywords: fluoroquinolones, magnetic dispersive micro extraction, nano-composite, self-doped polyaniline nanofibers

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Authors: Jigar Shaileshumar Halpati, Aravind Kumar Chandiran

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Vacancy ordered double perovskites (VOPs) have been significantly attracting researchers due to their chemical structure diversity and interesting optoelectronic properties. Some VOPs have been recently reported to be suitable photoelectrodes for photoelectrochemical water-splitting reactions due to their high stability and panchromatic absorption. In this work, we systematically synthesized mixed tetravalent VOPs based on Cs₂RuₘPt₁-ₘX₆ (X = Cl-, Br-) and reported their structural, optical, electrochemical and photoelectrochemical properties. The structural characterization confirms that the mixed tetravalent site intermediates formed their own phases. The parent materials, as well as their intermediates, were found to be stable in ambient conditions for over 1 year and also showed incredible stability in harsh pH media ranging from pH 1 to pH 11. Moreover, these materials showed panchromatic absorption with onset up to 1000 nm depending upon the mixture stoichiometry. The extraordinary stability and excellent absorption properties make them suitable materials for photoelectrochemical water-splitting applications. PEC studies of these series of materials showed a high water oxidation photocurrent of 0.56 mA cm-² for Cs₂Ru₀.₅Pt₀.₅Cl₆. Fundamental investigation from photoelectrochemical reactions revealed that the intrinsic ruthenium-based VOP showed enhanced hole transfer to the electrolyte, while the intrinsic platinum-based VOP showed higher photovoltage. The mix of these end members at the tetravalent site showed a synergic effect of reduced charge transfer resistance from the material to the electrolyte and increased photovoltage, which led to increased PEC performance of the intermediate materials.

Keywords: solar water splitting, photo electrochemistry, photo absorbers, material characterization, device characterization, green hydrogen

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Authors: Paolo Di Pietro, Matteo Lelli, Kinjal Parmar

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Water hazards are consistently identified as among the highest global risks in terms of impact. Riverbank protection plays a key role in flood risk management. For erosion control and scour protection, flexible solutions like gabions & mattresses are being used since quite some time now. The efficacy of erosion control systems depends both on the ability to prevent soil loss underneath, as well as to maintain their integrity under the effects of the water flow. The paper presents the results of a research carried out at the Colorado State University on the performance of double twisted wire mesh products, known as Reno Mattresses, used as soil erosion control system. Mattresses were subjected to various flow conditions on a 10m long flume where they were placed on a 0.30 m thick soil layer. The performance against erosion was evaluated by assessing the effect of the stone motion inside the mattress combined with the condition of incipient soil erosion underneath, in relationship to the mattress thickness, the filling stone properties and under variable hydraulic flow regimes. While confirming the stability obtained using a conventional design approach (commonly referred to tractive force theories), the results of the research allowed to introduce a new performance limit based on incipient soil erosion underneath the revetment. Based on the research results, the authors propose to express the shear resistance of mattresses used as soil erosion control system as a function of the size of the filling stones, their uniformity, their unit weight, the thickness of the mattress, and the presence of vertical connecting elements between the mattress lid and bottom.

Keywords: Reno Mattress, riverbank protection, hydraulics, full scale tests

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Authors: Mohammad Alkhatatbeh, Nehad Ayoub, Nizar Mhaidat, Nesreen Saadeh, Lisa Lincz

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CD36 is involved in the development of atherosclerosis by enhancing macrophage endocytosis of oxidized-low density lipoproteins and foam cell formation. Soluble CD36 (sCD36) was found to be elevated in type 2 diabetic patients and was supposed to act as a marker of insulin resistance and atherosclerosis. In young subjects, sCD36 was associated with cardiovascular risk factors including obesity and hypertriglyceridemia. This study was conducted to further investigate the relationship between plasma sCD36 and cardiovascular risk factors among middle-aged patients with metabolic syndrome (MetS) and healthy controls. SCD36 concentrations were determined by enzyme-linked immunosorbent assays (ELISA) for 41 patients with MetS and 36 healthy controls. Data for other variables were obtained from patients' medical records. SCD36 concentrations were relatively low compared to most other studies and were not significantly different between the MetS group and controls (P-value=0.17). SCD36 was also not correlated with age, body mass index, glucose, lipid profile, serum electrolytes and blood counts. SCD36 was not significantly different between subjects with obesity, hyperglycemia, dyslipidemia, hypertension or cardiovascular disease and those without these abnormalities (P-value > 0.05). The inconsistency between results reported in this study and other studies may be unique to the study population or be a result of the lack of a reliable standardized method for determining absolute sCD36 concentrations. However, further investigations are required to assess CD36 tissue expression in the study population and to assess the accuracy of various commercially available sCD36 ELISA kits. Thus, the availability of a standardized simple sCD36 ELISA that could be performed in any basic laboratory would be more favorable to the specialized flow cytometry methods that detect CD36+ microparticles if it was to be used as a biomarker.

Keywords: metabolic syndrome, CD36, cardiovascular risk, obesity, type 2 diabetes mellitus

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Authors: Palak J. Shukla, Atul K. Desai, Chentankumar D. Modhera

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For any country in the world, it has become a priority to protect the critical infrastructure from looming risks of terrorism. In any infrastructure system, the structural elements like lower floors, exterior columns, walls etc. are key elements which are the most susceptible to damage due to blast load. The present study revisits the state of art review of the design and analysis of reinforced concrete panels subjected to blast loading. Various aspects in association with blast loading on structure, i.e. estimation of blast load, experimental works carried out previously, the numerical simulation tools, various material models, etc. are considered for exploring the current practices adopted worldwide. Discussion on various parametric studies to investigate the effect of reinforcement ratios, thickness of slab, different charge weight and standoff distance is also made. It was observed that for the simulation of blast load, CONWEP blast function or equivalent numerical equations were successfully employed by many researchers. The study of literature indicates that the researches were carried out using experimental works and numerical simulation using well known generalized finite element methods, i.e. LS-DYNA, ABAQUS, AUTODYN. Many researchers recommended to use concrete damage model to represent concrete and plastic kinematic material model to represent steel under action of blast loads for most of the numerical simulations. Most of the studies reveal that the increase reinforcement ratio, thickness of slab, standoff distance was resulted in better blast resistance performance of reinforced concrete panel. The study summarizes the various research results and appends the present state of knowledge for the structures exposed to blast loading.

Keywords: blast phenomenon, experimental methods, material models, numerical methods

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Authors: Sima Parvizi Omran, Rezvan Tavakoli, Mahnaz Safari, Mohammadreza Aghasadeghi, Abolfazl Fateh, Pooneh Rahimi

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Background: SARS-CoV-2, a single-stranded RNA betacoronavirus causes the global outbreak of coronavirus disease 2019 (COVID-19). Several clinical and scientific concerns are raised by this pandemic. Genetic factors can contribute to pathogenesis and disease susceptibility. There are single nucleotide polymorphisms (SNPs) in many of the genes in the immune system that affect the expression of specific genes or functions of some proteins related to immune responses against viral infections. In this study, we analyzed the impact of polymorphism in the interferon alpha and beta receptor subunit 2 (IFNAR2) and dipeptidyl peptidase 9 (Dpp9) genes and clinical parameters on the susceptibility and resistance to Coronavirus disease (COVID-19). Methods: A total of 330- SARS-CoV-2 positive patients (188 survivors and 142 nonsurvivors) were included in this study. All single-nucleotide polymorphisms (SNPs) on IFNAR2 (rs2236757) and Dpp9 (rs2109069) were genotyped by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Results: In survivor patients, the frequency of the favourable genotypes of IFNAR2 SNP (rs2236757 GC) was significantly higher than in nonsurvivor patients, and also Dpp9 (rs2109069 AT) genotypes were associated with the severity of COVID-19 infection. Conclusions: This study demonstrated that the severity of COVID- 19 patients was strongly associated with clinical parameters and unfavourable IFNAR2, Dpp9 SNP genotypes. In order to establish the relationship between host genetic factors and the severity of COVID-19 infection, further studies are needed in multiple parts of the world.

Keywords: SARS-CoV-2, COVID-19, interferon alpha and beta receptor subunit 2, dipeptidyl peptidase 9, single-nucleotide polymorphisms

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Authors: Babak Bahri, Fatemeh Yassaee Meybodi, Changiz Eslahchi

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In the pursuit of effective cancer therapies, the exploration of combinatorial drug regimens is crucial to leverage synergistic interactions between drugs, thereby improving treatment efficacy and overcoming drug resistance. However, identifying synergistic drug pairs poses challenges due to the vast combinatorial space and limitations of experimental approaches. This study introduces ClusterSyn, a machine learning (ML)-powered framework for classifying anti-cancer drug synergy scores. ClusterSyn employs a two-step approach involving drug clustering and synergy score prediction using a fully connected deep neural network. For each cell line in the training dataset, a drug graph is constructed, with nodes representing drugs and edge weights denoting synergy scores between drug pairs. Drugs are clustered using the Markov clustering (MCL) algorithm, and vectors representing the similarity of drug pairs to each cluster are input into the deep neural network for synergy score prediction (synergy or antagonism). Clustering results demonstrate effective grouping of drugs based on synergy scores, aligning similar synergy profiles. Subsequently, neural network predictions and synergy scores of the two drugs on others within their clusters are used to predict the synergy score of the considered drug pair. This approach facilitates comparative analysis with clustering and regression-based methods, revealing the superior performance of ClusterSyn over state-of-the-art methods like DeepSynergy and DeepDDS on diverse datasets such as Oniel and Almanac. The results highlight the remarkable potential of ClusterSyn as a versatile tool for predicting anti-cancer drug synergy scores.

Keywords: drug synergy, clustering, prediction, machine learning., deep learning

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Authors: Fariha Akhter Chowdhury, Sabrina Mahboob, Anamika Saha, Afrin Jahan, Mohammad Nurul Islam

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Urinary tract infection (UTI) is frequently experienced by the female population where the prevalence increases with aging. Escherichia coli, one of the most common UTI causing organisms, retains glutathione defense mechanism that aids the organism to withstand the harsh physiological environment of urinary tract, host oxidative immune response and even to affect antibiotic-mediated cell death and the emergence of resistance. In this study, we aimed to investigate the glutathione reductase activity of uropathogenic E. coli (UPEC) by observing the reduced glutathione (GSH) level alteration under stressful condition. Urine samples of 58 patients with UTI were collected. Upon isolation and identification, 88% of the samples presented E. coli as UTI causing organism among which randomly selected isolates (n=9), obtained from urine samples of female patients, were considered for this study. E. coli isolates were grown under normal and stressful conditions where H₂O₂ was used as the stress-inducing agent. GSH level estimation of the isolates in both conditions was carried out based on the colorimetric measurement of 5,5'-dithio-bis (2-nitrobenzoic acid) (DTNB) and GSH reaction product using microplate reader assay. The GSH level of isolated E. coli sampled from adult patients decreased under stress compared to normal condition (p = 0.011). On the other hand, GSH production increased markedly in samples that were collected from elderly subjects (p = 0.024). A significant partial correlation between age and change of GSH level was found as well (p = 0.007). This study may help to reveal ways for better understanding of E. coli pathogenesis of UTI prevalence in elderly patients.

Keywords: Escherichia coli, glutathione reductase activity, oxidative stress, reduced glutathione (GSH), urinary tract infection (UTI)

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Authors: Getamesay Kassaye Dimru

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The cultivation of fruit tree in degraded areas has two-fold importance. Firstly, it improves food availability and income, and secondly, it promotes the conservation of soil and water improving, in turn, the productivity of the land. The main objectives of this study are to identify the determinant of farmer's fruit trees plantation decision and to major fruit production challenges and opportunities of the study area. The analysis was made using primary data collected from 60 sample household selected randomly from the study area in 2016. The primary data was supplemented by data collected from a key informant. In addition to the descriptive statistics and statistical tests (Chi-square test and t-test), a logit model was employed to identify the determinant of fruit tree plantation decision. Drought, pest incidence, land degradation, lack of input, lack of capital and irrigation schemes maintenance, lack of misuse of irrigation water and limited agricultural personnel are the major production constraints identified. The opportunities that need to further exploited are better access to irrigation, main road access, endowment of preferred guava variety, experience of farmers, and proximity of the study area to research center. The result of logit model shows that from different factors hypothesized to determine fruit tree plantation decision, age of the household head accesses to market and perception of farmers about fruits' disease and pest resistance are found to be significant. The result has revealed important implications for the promotion of fruit production for both land degradation control and rehabilitation and increasing the livelihood of farming households.

Keywords: degradation, fruit, irrigation, pest

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Authors: Renu Sisodia

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This paper attempted to explore and explain the local level river water conflicts in the larger context of state - society relations. This study also covered causes of local level river water conflicts in the catchment area of Bandi and Arvari river of Rajasthan. The focus of the study was on the emergence of community driven, decentralised management of river water bodies and strategies used by local communities to protect and manage river water conflicts. The research is conducted through the process of designing a framework based on essential theoretical and practical findings supported by primary and secondary data. Two in depth case study is conducted to understand the phenomenon in depth. The first field site is Bandi River of Pali district, which is about the struggle between textile industries, community and the State government in which water pollution is said to be one of the driving force of the conflict. Finding shows that the state is supporting textile industries in Pali district have not been adherent to the environmental ethics. Present legal infrastructure and local institutions fail to resolve the serious problem of water pollution in Bandi River and its adverse impact on the local community as a result local community resistance against the local administration and the state government. The second case illustrates the plight of Arvari River in Alwar district. Tussle for the ownership of fisheries between local community, the private fish contractor and State government has been the main bone of contestation. To resolve this conflict local community formed conflict management mechanism named as Arvari Parliament. Arvari Parliament has its own principle and rules to resolve water conflicts related to ownership of the river and use of the river water. The research findings also highlight the co-existence between conventional and modern practices in resolving conflicts.

Keywords: water, water pollution, water conflicts, water scarcity, conflict resolution, local community

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Authors: Abdullah Ansari, Sinika Rambaran, Sirpaul Jaikishun

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Vermiwash could be used to enhance plant productivity and resistance to some harmful plant pathogens, as well as provide benefit through the disposal of waste matter. Alternaria rot caused by the fungus Alternaria alternata (Fr.) Keissl., is a common soil-borne pathogen that results in postharvest fruit rot of cucumbers, peppers and other cash crops. The production and distribution of Cucumis sativus L. (cucumber) could be severely affected by Alternaria rot. Fungicides are the traditional treatment however; they are not only expensive but can also cause environmental and health problems. Vermiwash was prepared from various medicinal plants (Ocimum tenuiflorum L. {Tulsi}, Azadirachta indica A. Juss. {neem}, Cymbopogon citratus (DC. ex Nees) Stapf. {lemon grass} and Oryza sativa L. {paddy straw} and applied, in vitro, to A. alternata to investigate their effectiveness as organic alternatives to traditional fungicides. All of the samples of vermiwash inhibited the growth of A. alternata. The inhibitive effects on the fungus appeared most effective when A. indica and O. tenuiflorum were used in the production of the vermiwash. Using the serial dilution method, vermiwash from O. tenuiflorum showed the highest percent of inhibition (93.2%), followed by C. citratus (74.7%), A. indica (68.7%), O. sativa, combination, and combination without worms. Using the sterile disc diffusion method, all of the samples produced zones of inhibition against A. alternata. Vermiwash from A. indica produced a zone of inhibition, averaging 15.3mm, followed by O. tenuiflorum (14.0mm), combination without worms, combination, C. citratus and O. sativa. Nystatin produced a zone of inhibition of 10mm. The results indicate that vermiwash is not simply an organic alternative to more traditional chemical fungicides, but it may in fact be a better and more effective product in treating certain fungal plant infections, particularly A. alternata.

Keywords: vermiwash, earthworms, soil, bacteria, alternaria alternata, antifungal, antibacterial

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Authors: Rukia Yosuf

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Diabetes is a national healthcare crisis related to both macrovascular and microvascular complications. We hypothesized that higher levels of physical activity are associated with lower total and visceral fat mass, lower systolic blood pressure, and increased insulin sensitivity. Participant inclusion criteria: 21-50 years old, BMI ≥ 30 kg/m2, hemoglobin A1C 5.7-6.4, fasting glucose 100-125 mg/dL, and HOMA IR ≥ 2.5. Exclusion criteria: history of diabetes, hypertension, HIV, renal disease, hearing loss, alcoholic intake over four drinks daily, use of organic nitrates or PDE5 inhibitors, and decreased cardiac function. Total physical activity was measured using accelerometers, body composition using DXA, and insulin resistance via fsIVGTT. Clinical and biochemical cardiometabolic risk factors, blood pressure and heart rate were obtained using a calibrated sphygmomanometer. Anthropometric measures, fasting glucose, insulin, lipid profile, C-reactive protein, and BMP were analyzed using standard procedures. Within our study, we found correlations between levels of physical activity in a heterogeneous group of prediabetic adults. Patients with more physical activity had a higher degree of insulin sensitivity, lower blood pressure, total visceral adipose tissue, and overall lower total mass. Total physical activity levels showed small, but significant correlations with systolic blood pressure, visceral fat, lean mass and insulin sensitivity. After normalizing for the race, age, and gender using multiple regression, these associations were no longer significant considering our small sample size. More research into prediabetes will decrease the population of diabetics overall. In the future, we could increase sample size and conduct cross sectional and longitudinal studies in various populations with prediabetes.

Keywords: diabetes, kidney disease, nephrology, prediabetes

Procedia PDF Downloads 185

Authors: Checkfaith I. Aizebeoje, Temitope O. Lawal, Bolanle A. Adeniyi

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The overuse and abuse of antibiotics in treating zoonotic infections in humans and opportunistic infections in rabbit has contributed to the increase in antimicrobial drug resistance, therefore, an alternative to antibiotics is needed in treating these infections. The study was carried out to determine the antimicrobial activity of lactic acid bacteria (LAB) isolated from rabbit’s faeces against multidrug-resistant (MDR) pathogens isolated from the same rabbit. Twelve faecal samples and twelve swabs from fur samples were randomly collected aseptically from apparently healthy rabbits from Ajibode, Ibadan and University of Ibadan research farm in Ibadan, Oyo state, Nigeria. Lactic acid bacteria and multidrug-resistant pathogens were isolated using appropriate agar media and identified by partial sequencing of the 16SrRNA gene. Antibiotic susceptibility pattern of isolated bacteria and LAB were determined by the agar diffusion method. The antibacterial activity of the LAB against the test pathogens was determined using the agar overlay and agar diffusion methods. The pathogens Myroides gitamensis, Citrobacter rodentium, Acinetobacter johnsonii, Enterobacter oryzendophyticus and Serratia marcescens as well as twenty-eight (28) species of LAB belonging to Acetobacter and Lactobacillus genera were identified and characterized. Lactobacillus plantarum had the highest (60.71%) occurrence of the LAB. Viable cells and cell free supernatant (CFS) of isolated LAB inhibited the growth of the test organisms with the largest zone of inhibition (40 mm) produced by Lactobacillus plantarum against Citrobacter rodentium. This study showed that LAB from rabbit possess considerable antibacterial activity against multidrug-resistant bacteria from the same environment.

Keywords: antibacterial activities, cell-free supernatant, lactic acid bacteria; multidrug-resistant pathogens, rabbits’ faeces

Procedia PDF Downloads 132

Authors: Mikael M. Johansson, Peter Stenvall, Leif Karlsson, Joel Andersson

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Sandvik Sanicro 25, UNS S31035, is an advanced high temperature austenitic stainless steel that potentially can be used in super-heaters and reheaters in the next generation of advanced ultra-super critical power plants. The material possesses both high creep strength and good corrosion resistance at temperatures up to 700°C. Its high temperature properties are positioned between other commercially available high temperature austenitic stainless steels and nickel-based alloys. It is, however, well known that an austenitic solidification mode combined with a fully austenitic microstructure exacerbate susceptibility towards hot cracking. The problem increases even more for thick walled material in multipass welding and could compromise the integrity of the welded component. Varestraint weldability testing is commonly used to evaluate susceptibility towards hot cracking of materials. In this paper, Varestraint test results are evaluated for base material of both UNS S31035 steel and are compared to those of the well-known and well-characterized UNS S31008 grade. The more creep resistant alloy, UNS S31035, is metallurgically more complicated than the UNS S31008 grade and has additions of several alloying elements to improve its high temperature properties. It benefits from both solid solution hardening as well as precipitation hardening. This investigation therefore attempts, based on the Varestraint weldability test, to understand if there are any differences in cracking mechanisms between these two grades due to the additional alloying elements used in UNS S31035. Results from Varestraint testing and crack type investigations will be presented and discussed in some detail. It is shown that hot cracking susceptibility of the UNS S31035 steel is only slightly higher than that of UNS S31008 despite the more complicated metallurgy. Weldability of the two alloys is therefore judged to be comparable making the newer alloy well suited also for critical applications.

Keywords: austenitic stainless steel, hot cracking susceptibility, UNS S31035, UNS S31008, varestraint weldability testing

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Authors: Dalia G. Aseel

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The potato (Solanum tubersum, L.) has become one of the major vegetable crops in Egypt and all over the world. Potato leafroll virus(PLRV) was observed on potato plants collected from different governorates in Egypt. Three cultivars, Spunta, Diamont, and Cara, infected with PLRV were collected; RNA was extracted and subjected to Real-Time PCR using the coat protein gene primers. The results showed that the expression of the coat protein was 39.6-fold, 12.45-fold, and 47.43-fold, respectively, for Spunta, Diamont, and Cara cultivars. Differential Display Polymerase Chain Reaction (DD-PCR) using pathogenesis-related protein 1 (PR-1), β-1,3-glucanases (PR-2), chitinase (PR-3), peroxidase (POD), and polyphenol oxidase (PPO) forward primers for pathogenesis-related proteins (PR). The obtained data revealed different banding patterns depending on the viral type and the region of infection. Regarding PLRV, 58 up-regulated and 19 down-regulated genes were detected. Sequence analysis of the up-and down-regulated genes revealed that infected plants were observed in comparison with the healthy control. Sequence analysis of the up-regulated gene was performed, and the encoding sequence analysis showed that the obtained genes include: induced stolen tip protein. On the other hand, two down-regulated genes were identified: disease resistance RPP-like protein and non-specific lipid-transfer protein. In this study, the expressions of PR-1, PR-2, PR-3, POD, and PPO genes in the infected leaves of three potato cultivars were estimated by quantitative real-time PCR. We can conclude that the PLRV-infection of potato plants inhibited the expression of the five PR genes. On the contrary, infected leaves by PLRV elevated the expression of some defense genes. This interaction may also induce and/or suppress the expression of some genes responsible for the plant's defense mechanisms.

Keywords: PLRV, pathogenesis-related proteins (PRs), DD-PCR, sequence, real-time PCR

Procedia PDF Downloads 141

Authors: P. Michael Preetam Raj, Souri Banerjee, Souvik Kundu

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Oxide based memristors were fabricated in order to establish its potential applications in analog/digital electronics. BaTiO₃-BiFeO₃ (BT-BFO) was employed as an active material, whereas platinum (Pt) and Nb-doped SrTiO₃ (Nb:STO) were served as a top and bottom electrodes, respectively. Piezoelectric force microscopy (PFM) was utilized to present the ferroelectricity and repeatable polarization inversion in the BT-BFO, demonstrating its effectiveness for resistive switching. The fabricated memristors exhibited excellent electrical characteristics, such as hysteresis current-voltage (I-V), high on/off ratio, high retention time, cyclic endurance, and low operating voltages. The band-alignment between the active material BT-BFO and the substrate Nb:STO was experimentally investigated using X-Ray photoelectron spectroscopy, and it attributed to staggered heterojunction alignment. An energy band diagram was proposed in order to understand the electrical transport in BT-BFO/Nb:STO heterojunction. It was identified that the I-V curves of these memristors have several discontinuities. Curve fitting technique was utilized to analyse the I-V characteristic, and the obtained I-V equations were found to be parabolic. Utilizing this analysis, a non-linear BT-BFO memristors equivalent circuit model was developed. Interestingly, the obtained equivalent circuit of the BT-BFO memristors mimics the identical electrical performance, those obtained in the fabricated devices. Based on the developed equivalent circuit, a finite state machine (FSM) design was proposed. Efforts were devoted to fabricate the same FSM, and the results were well matched with those in the simulated FSM devices. Its multilevel noise filtering and immunity to external noise characteristics were also studied. Further, the feature of variable negative resistance was established by controlling the current through the memristor.

Keywords: band alignment, finite state machine, polarization inversion, resistive switching

Procedia PDF Downloads 130

Authors: C. Sánchez de Rojas Candela, A. Riquelme, P. Rodrigo, M. D. Escalera-Rodríguez, B. Torres, J. Rams

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Selective laser melting is one of the most commonly used AM techniques. In it, a thin layer of metallic powder is deposited, and a laser is used to melt selected zones. The accumulation of layers, each one molten in the preselected zones, gives rise to the formation of a 3D sample with a nearly arbitrary design. To ensure that the properties of the final parts match those of the powder, all the process is carried out in an inert atmosphere, preferentially Ar, although this gas could be substituted. Ti6Al4V alloy is widely used in multiple industrial applications such as aerospace, maritime transport and biomedical, due to its properties. However, due to the demanding requirements of these applications, greater hardness and wear resistance are necessary, together with a better machining capacity, which currently limits its commercialization. To improve these properties, in this study, Selective Laser Melting (SLM) is used to manufacture Ti/TiN metal matrix composites with in-situ and ex-situ titanium nitride reinforcement where the scanning speed is modified (from 28.5 up to 65 mm/s) to study the influence of the processing parameters in SLM. A one-step method of nitriding the Ti6Al4V alloy is carried out to create in-situ TiN reinforcement in a reactive atmosphere and it is compared with ex-situ composites manufactured by previous mixture of both the titanium alloy powder and the ceramic reinforcement particles. The microstructure and mechanical properties of the different Ti/TiN composite materials have been analyzed. As a result, the existence of a similar matrix has been confirmed in in-situ and ex-situ fabrications and the growth mechanisms of the nitrides have been studied. An increase in the mechanical properties with respect to the initial alloy has been observed in both cases and related to changes in their microstructure. Specifically, a greater improvement (around 30.65%) has been identified in those manufactured by the in-situ method at low speeds although other properties such as porosity must be improved for their future industrial applicability.

Keywords: in-situ reinforcement, nitriding reaction, selective laser melting, titanium nitride

Procedia PDF Downloads 78

Authors: Vaishakh Medikeri

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Lightning, the marvelous, spectacular and the awesome truth of nature is one of the greatest energy sources left unharnessed since ages. A single lightning bolt of lightning contains energy of about 15 billion joules. This huge amount of energy cannot be harnessed completely but partially. This paper proposes to harness the energy from lightning strikes. Throughout the globe the frequency of lightning is 40-50 flashes per second, totally 1.4 billion flashes per year; all of these flashes carrying an average energy of about 15 billion joules each. When a lightning bolt strikes the ground, tremendous amounts of energy is transferred to earth which propagates in the form of concentric circular energy waves. These waves have a frequency of about 7.83Hz. Harvesting the lightning bolt directly seems impossible, but harvesting the energy waves produced by the lightning is pretty easier. This can be done using a tricoil energy harnesser which is a new device which I have invented. We know that lightning bolt seeks the path which has minimum resistance down to the earth. For this we can make a lightning rod about 100 meters high. Now the lightning rod is attached to the tricoil energy harnesser. The tricoil energy harnesser contains three coils whose centers are collinear and all the coils are parallel to the ground. The first coil has one of its ends connected to the lightning rod and the other end grounded. There is a secondary coil wound on the first coil with one of its end grounded and the other end pointing to the ground and left unconnected and placed a little bit above the ground so that this end of the coil produces more intense currents, hence producing intense energy waves. The first coil produces very high magnetic fields and induces them in the second and third coils. Along with the magnetic fields induced by the first coil, the energy waves which are currents also flow through the second and the third coils. The second and the third coils are connected to a generator which in turn is connected to a capacitor which stores the electrical energy. The first coil is placed in the middle of the second and the third coil. The stored energy can be used for transmission of electricity. This new technique of harnessing the lightning strikes would be most efficient in places with more probability of the lightning strikes. Since we are using a lightning rod sufficiently long, the probability of cloud to ground strikes is increased. If the proposed apparatus is implemented, it would be a great source of pure and clean energy.

Keywords: generator, lightning rod, tricoil energy harnesser, harvesting energy

Procedia PDF Downloads 378

Authors: Rashid S. Mohammad, Shicheng Zhang, Xinzhe Zhao

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In tight oil reservoirs, wettability alteration has generally been considered as an effective way to remove fracturing fluid retention on the surface of the fracture and consequently improved oil production. However, there is a lack of a reliable productivity prediction model to show the relationship between the wettability and oil production in tight oil well. In this paper, a new oil productivity prediction model of immiscible oil-water flow and miscible CO₂-oil flow accounting for wettability is developed. This mathematical model is established by considering two different length scales: nonporous network and propped fractures. CO₂ flow diffuses in the nonporous network and high velocity non-Darcy flow in propped fractures are considered by taking into account the effect of wettability alteration on capillary pressure and relative permeability. A laboratory experiment is also conducted here to validate this model. Laboratory experiments have been designed to compare the water saturation profiles for different contact angle, revealing the fluid retention in rock pores that affects capillary force and relative permeability. Four kinds of brines with different concentrations are selected here to create different contact angles. In water-wet porous media, as the system becomes more oil-wet, water saturation decreases. As a result, oil relative permeability increases. On the other hand, capillary pressure which is the resistance for the oil flow increases as well. The oil production change due to wettability alteration is the result of the comprehensive changes of oil relative permeability and capillary pressure. The results indicate that wettability is a key factor for fracturing fluid retention removal and oil enhancement in tight reservoirs. By incorporating laboratory test into a mathematical model, this work shows the relationship between wettability and oil production is not a simple linear pattern but a parabolic one. Additionally, it can be used for a better understanding of optimization design of fracturing fluids.

Keywords: wettability, relative permeability, fluid retention, oil production, unconventional and tight reservoirs

Procedia PDF Downloads 235