108 research outputs found

    Numerical Analysis of Carbon Fiber Reinforced Plastic (CFRP) Shear Walls and Steel Strips under Cyclic Loads Using Finite Element Method

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    Reinforced concrete shear walls are the main elements of resistance against lateral loads in reinforced concrete structures. These walls should not only provide sufficient resistance but also provide sufficient ductility in order to avoid brittle fracture, particularly under strong seismic loads. However, many reinforced concrete shear walls need to be stabilized and reinforced due to various reasons such as changes in requirements of seismic regulations, weaknesses in design and execution, passage of time, damaging environmental factors, patch of rebar in plastic hinges and in some cases failures and weaknesses caused by previous earthquakes or explosion loads. Recently, Fiber Reinforced Polymer (FRP) components have been extensively and successfully used in seismic improvement. This study reinforces FRP reinforced concrete shear walls and steel strips. CFRP and steel strips are evaluated by different yield and ultimate strength. Numerical and experimental studies are done on walls with scale 1/2. These walls are exposed to cyclic loading. Hysteresis curves of force, drift and strain of FRP strips are reviewed in order to compare results of numerical work and laboratory results. Both numerical and laboratory results show that CFRP and steel strips increase resistance, capacity and ductility of the structure

    Systematic review on safety and drug interaction of herbal therapy in hyperlipidemia: a guide for internist.

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    Because of reporting high side effects related to biosynthetic drugs, recent attention has been paid to the use of herbs instead of chemical drugs to balance serum lipids. The present systematic review aimed to evaluate the safety of herbal medicines and also to assess drug interaction in herbal therapy in treating hyperlipidemia. The international research databases including MEDLINE; Google scholar, Web of Science SciVerse Scopus (SCOPUS); EBSCO Academic Search; Cochrane Central Register of Controlled Trials (CENTRAL); and a Chinese database (China Network Knowledge Infrastructure [CNKI]) were searched from their respective inceptions up to September 2014 with the search terms of "hyperlipidemia", "herbal medicine", "medicine traditional", "extract plant", "Traditional Medicine" and "Chinese Herbal Medicine" without narrowing or limiting search elements. A total of 85 randomized clinical trials (RCTs) studies were finally assessed on human subjects. A notable number of herbal drugs that are commonly used as an anti-hyperlipidemia agent may be interacted with a variety of biosynthetic drugs. In this regard, the most common reported herb-drug reactions were related to anticoagulants, antidepressants, anti-epileptic, anti-inflammatory, and/or even antihypertension and anti-lipidemic drugs. Also, a considerable number of anti-lipidemic drugs of plants origin may be accompanied with metabolic disturbances and serious complications within pregnancy and breast feeding. The main fundamental principles for administration of these drugs include physicians' complete awareness of the effects and interactions of these drugs, educating people not taking these drugs arbitrarily, and closely monitoring the verification and distribution of the drugs in the society

    Mesenchymal Stem Cells Promote Mammosphere Formation and Decrease E-Cadherin in Normal and Malignant Breast Cells

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    Normal and malignant breast tissue contains a rare population of multi-potent cells with the capacity to self-renew, referred to as stem cells, or tumor initiating cells (TIC). These cells can be enriched by growth as "mammospheres" in three-dimensional cultures.We tested the hypothesis that human bone-marrow derived mesenchymal stem cells (MSC), which are known to support tumor growth and metastasis, increase mammosphere formation.We found that MSC increased human mammary epithelial cell (HMEC) mammosphere formation in a dose-dependent manner. A similar increase in sphere formation was seen in human inflammatory (SUM149) and non-inflammatory breast cancer cell lines (MCF-7) but not in primary inflammatory breast cancer cells (MDA-IBC-3). We determined that increased mammosphere formation can be mediated by secreted factors as MSC conditioned media from MSC spheroids significantly increased HMEC, MCF-7 and SUM149 mammosphere formation by 6.4 to 21-fold. Mammospheres grown in MSC conditioned media had lower levels of the cell adhesion protein, E-cadherin, and increased expression of N-cadherin in SUM149 and HMEC cells, characteristic of a pro-invasive mesenchymal phenotype. Co-injection with MSC in vivo resulted in a reduced latency time to develop detectable MCF-7 and MDA-IBC-3 tumors and increased the growth of MDA-IBC-3 tumors. Furthermore, E-cadherin expression was decreased in MDA-IBC-3 xenografts with co-injection of MSC.MSC increase the efficiency of primary mammosphere formation in normal and malignant breast cells and decrease E-cadherin expression, a biologic event associated with breast cancer progression and resistance to therapy

    Physical property characterization of single step synthesized NdFeAsO0.80F0.20 bulk 50K superconductor

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    We report an easy single step synthesis route of title compound NdFeAsO0.80F0.20 superconductor having bulk superconductivity below 50 K. The title compound is synthesized via solid-state reaction route by encapsulation in an evacuated (10-3 Torr) quartz tube. Rietveld analysis of powder X-ray diffraction data shows that compound crystallized in tetragonal structure with space group P4/nmm. R(T)H measurements showed superconductivity with Tc (R=0) at 48 K and a very high upper critical field (Hc2) of up to 345 Tesla. Magnetic measurements exhibited bulk superconductivity in terms of diamagnetic onset below 50 K. The lower critical field (Hc1) is around 1000 Oe at 5 K. In normal state i.e., above 60 K, the compound exhibited purely paramagnetic behavior and thus ruling out the presence of any ordered FeOx impurity in the matrix. In specific heat measurements a jump is observed in the vicinity of superconducting transition (Tc) along with an upturn at below T=4 K due to the AFM ordering of Nd+3 ions in the system. The Thermo-electric power (TEP) is negative down to Tc, thus indicating dominant carriers to be of n-type in NdFeAsO0.80F0.20 superconductor. The granularity of the bulk superconducting NdFeAsO0.8F0.2 sample is investigated and the intra and inter grain contributions have been individuated by looking at various amplitude and frequencies of the applied AC drive magnetic field.Comment: 26pages text + Figures: comments/suggestions welcome ([email protected] & http://www.freewebs.com/vpsawana

    An experimental and analytical investigation of reinforced concrete beam-column joints strengthened with a range of CFRP schemes applied only to the beam

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    This paper investigates the experimental and analytical behaviour of beam-column joints that are subjected to a combination of torque, flexural and direct shear forces, where different Carbon Fibre Polymer (CFRP) strengthening wraps have been applied only to the beam. These wrapping schemes have previously been determined by the research community as an effective method of enhancing the torsional capacities of simply supported reinforced concrete beams. In this investigation, four 3/4-scale exterior beam-column joints were subjected to combined monotonic loading; three different beam wrapping schemes were employed to strengthen the beam region of the joint. The paper suggests a series of rational formulae, based on the space truss mechanism, which can be used to evaluate the joint shear demand of the beams wrapped in these various ways. Further, an iterative model, based on the average stress-strain method, has been introduced to predict joint strength. The proposed analytical approaches show good agreement with the experimental results. The experimental outcomes along with the adopted analytical methods reflect the consistent influence of the wrapping ratio, the interaction between the combined forces, the concrete strut capacity and the fibre orientation on the joint forces, the failure mode and the distortion levels. A large rise in the strut force resulting from shear stresses generated from this combination of forces is demonstrated and leads to a sudden-brittle failure. Likewise, increases in the beams’ main steel rebar strains are identified at the column face, again influenced by the load interactions and the wrapping systems used

    Therapeutic potentials of Nigella sativa preparations and its constituents in the management of diabetes and its complications in experimental animals and patients with diabetes mellitus: A systematic review

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    Objective: The purpose of this up-to-date comprehensive systematic review was to evaluate and summarize all research studies in the field in order to clarify the magnitude of Nigella sativa (N. sativa) effects on the management of Diabetes mellitus (DM) and its complications. Methods: A systematic review was conducted in a Cochrane style and in accordance PRISMA checklist using the published studies in PubMed/MEDLINE, SCOPUS, and EMBASE databases that were searched up to January 2019. Abstracts that met PICO criteria for qualitative studies underwent dual review for data extraction to evaluate study quality and details. Results: Dietary supplementation with N. sativa preparations can improve various secondary complications of diabetic patients. N. sativa preparations possess antidiabetic, hypoglycemic, anti-hyperlipidemic, antihypertensive, and anti-obesity effects. Beneficial effects of N. sativa preparations include the restoration of the antioxidant defense systems, the increase in the activity of antioxidant enzymes, the decrease of inflammatory biomarkers, the suppression of the production pro-inflammatory mediators, improvement of endothelial dysfunction, and hepatic, kidney, heart and immune system functions. They have key roles in managing diabetes-induced inflammation and oxidative stress in diabetic patients. Conclusion: N. sativa preparations have key roles in herbal medicine as an adjuvant in the treatment and management of patients with DM and its complications. Moreover, the beneficial effects of N. sativa preparations were differently based on dosage forms, active ingredients, and duration of intervention. The best dosage to improve glycemic indices and lipid and lipoprotein profiles is 2 g daily powdered N. sativa for at least 12 weeks. © 2020 Elsevier Lt

    Normal state conduction in Gd(Ba 2–x Pr x)Cu 3O 7+δ

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    The normal state resistivity of single phase polycrystalline Gd(Ba 2–x Pr x )Cu 3O 7+δ samples with 0.0≤x≤0.50 have been investigated. There is a distinct metal-insulator transition at % MathType!MTEF!2!1!+- % feaafaart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEamaaDa % aaleaacaWGJbaabaGaaeytaiaabMeacaqGubaaaOGaeyypa0JaaGim % aiaac6cacaaIYaaaaa!3DA8! xcMIT=0.2 x_c^{{\rm{MIT}}} =0.2 and a superconductor-insulator transition at % MathType!MTEF!2!1!+- % feaafaart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEamaaDa % aaleaacaWGJbaabaGaae4uaiaabMeacaqGubaaaOGaeyypa0JaaGim % aiaac6cacaaIZaGaaGynaaaa!3E6E! xcSIT=0.35 x_c^{{\rm{SIT}}} =0.35 with the increase of x. The two-dimensional variable range hopping is dominant in the normal state resistivity of the samples. The localization length, hopping range, and hopping energy of carriers show that Pr doping strongly localizes the carriers in normal state, and finally causes the suppression of superconductivity. Copyright EDP Sciences, Springer-Verlag 200374.25.Fy Transport properties (electric and thermal conductivity , thermoelectric effects, etc.), 74.72.Bk Y-based cuprates, 71.30.+h Metal-insulator transitions and other electronic transitions,
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