In order to solve the bottleneck problems including uniform distribution, and oxidation resistance of nano carbons in oxide ceramics, c/MgAl2O4 composite powders were prepared with Mgc2O4 center dot 2H(2)O, MgO2, Al2O...
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In order to solve the bottleneck problems including uniform distribution, and oxidation resistance of nano carbons in oxide ceramics, c/MgAl2O4 composite powders were prepared with Mgc2O4 center dot 2H(2)O, MgO2, Al2O3, and Al as raw materials via combustion method under argon atmosphere. The maximum adding amount of Mgc2O4 center dot 2H(2)O is 34.34 wt%. The phase compositions and microstructures of combustion products were characterized through X-ray diffraction (XRD), scanning electron microscope (SEM)/EDX, and Raman spectroscopy. The results showed that the phases of products are mainly composed of MgAl2O4 and carbon. The prepared MgAl2O4 has granular and rod-like morphologies, and the free carbon (1.172 wt%) exists between particles of MgAl2O4. Moreover, the addition of Fec2O4 as catalyst in raw materials ratio would be beneficial for improving crystallization of in situ carbon generated in the products. The oxidation activation energy of the prepared c/MgAl2O4 composite powders was calculated as 143.01 kJ/mol which was 22.17% higher than that of carbon black/MgAl2O4 powders (117.06 kJ/mol), suggesting that the c/MgAl2O4 composite powders prepared by combustion synthesis have excellent oxidation resistance.
Aluminium alloy 6063-T6 is a popular choice among different industrial sectors as it portrays various desirable properties like moderate strength, improved corrosion resistance, better weldability and formability etc....
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Aluminium alloy 6063-T6 is a popular choice among different industrial sectors as it portrays various desirable properties like moderate strength, improved corrosion resistance, better weldability and formability etc. These advantages make AA6063-T6 a common choice for matrix in a metal matrix composite. Mostly conventional fusion welding methods like Metal Inert Gas (MIG) and Tungsten Inert Gas (TIG) seem preferable options for welding aluminium and its alloys but it remains a challenge to use them to weld aluminium metal matrix composite. A modified version of MIG i.e. cMT welding, can be explored to overcome the challenges. In this study, an aluminium metal matrix composite has been fabricated with AA6063-T6 as matrix and two reinforcements −one organic, i.e., Eggshell (ES) and one inorganic, i.e., Boron carbide (B 4 c), using the conventional stir casting method. cMT welding has been performed on plates cut out from the composites. Microstructure, hardness, tensile strength and residual stress of weld joint of composite have been observed. From micrographs, it is observed that a finer grain has been formed at the Fusion Zone (FZ) in comparison to the Heat Affected Zone (HAZ) and Parent Material (PM). XRD analysis at the fusion line has identified several intermetallic stoichiometriccompounds (Al 12 Mg 17 , Mg 2 Si, caMgSi, caO, B 2 O 3 ) and reinforcement B 4 c and cacO 3 within the matrix volume. The FZ exhibits higher hardness than the HAZ and the PM. Further, the tensile strength of the FZ exceeds that of the unwelded composite due to the presence of metastable strengthening phases of Mg 2 Si in the FZ, along with reinforcement (B 4 c and ES) particles. Residual stress analysis reveals tensile stress in the FZ and more compressive stress in the HAZ than in the PM.
We consider the stochastic queue core problem on a tree network. Our aim is to find an optimal path on a tree network subject to the average travel time of particles moving along the tree for service given by a server...
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We consider the stochastic queue core problem on a tree network. Our aim is to find an optimal path on a tree network subject to the average travel time of particles moving along the tree for service given by a server traversing along the optimal path. We assume that particles originating at a node on a tree network request their demands for service randomly and the server is modeled first by an M/M/1 and then by an M/G/1 queue using the FIFO discipline. We consider that all paths along which the particles travel are modeled with an M/G/c/c state-dependent queue with the particles being independent of each other having demands according to the Poisson distribution. Two algorithms are developed for computing the optimal path on a tree network along with the M/M/1 and the M/G/1 queues. The computational complexity of the algorithms and illustrative numerical results obtained by implementations of the algorithms in MATLAB software environment are given.
Background: chronic hepatitis c infection is common among people with history of substance use. Liver fibrosis assessment is a barrier to linkage to care, particularly among those with history of substance users. The ...
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Background: chronic hepatitis c infection is common among people with history of substance use. Liver fibrosis assessment is a barrier to linkage to care, particularly among those with history of substance users. The use of non-invasive scores can be helpful in predicting liver cirrhosis in the era of HcV elimination, especially in countries where transient elastography(TE) is not available. We compared the commonly used non-invasive scores with a novel non-invasive score in predicting liver cirrhosis in this population. Methods: HcV patients with history of substance use between 2011 and 2016 were analyzed. All patients had TE for liver fibrosis assessment. clinical performance of established non-invasive scores for fibrosis assessment and novel score were compared. Youden's index was used to determine optimal cut-off of the novel score. Results: A total of 579 patients were included. In multivariate logistic regression, cirrhosis on TE was associated with age( P = 0.002), aspartate aminotransferase(AST)( P = 0.004), and platelet count( P < 0.001), but not alanine aminotransferase(ALT)( P = 0.896). These form the components of modified AST-toplatelet ratio index(APRI) score. Modified APRI was superior to APRI in predicting cirrhosis(AUROc, 0.796 vs. 0.770, P = 0.007), but not fibrosis-4 score(FIB-4)( P = 1.00). Modified APRI at cut-off of 4 has sensitivity, specificity and negative predictive value(NPV) of 94.4%, 26.9% and 92.6%, respectively, and at 19, has sensitivity, specificity and positive predictive value(PPV) of 33.3%, 96.2% and 77.1%, respectively. FIB-4 has a NPV and PPV of 88.6%, 41.8% and 78.5%, 77.6%, at cut-off of 1.45 and 3.25, respectively. Using the cut-off of 4 and 14 for modified APRI, 32.5% of patients can be correctly classified and misses out only 5.6% of cirrhosis patients. conclusions: Modified APRI score is superior in predicting cirrhosis in HcV population, with 32.5% of the population being correctly classified using cut-off of 4 and 14.
A series of LiFePO4/ccomposites are prepared under the conditions of pH = 3, 5, 7, 8, 9 via biosynthesis method. The X-ray diffraction demonstrates that all of well-crystallized LiFePO4/ccomposites can be successful...
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A series of LiFePO4/ccomposites are prepared under the conditions of pH = 3, 5, 7, 8, 9 via biosynthesis method. The X-ray diffraction demonstrates that all of well-crystallized LiFePO4/ccomposites can be successfully prepared by adjusting the pH value. The images of scanning electron microscopy show that the structure and size of different samples have obvious changes. Besides, the LiFePO4/ccomposite prepared at the value of 8 delivers a best discharge capacity of 158.7 mAh/g at 0.1 c. The results show that the electrochemical performance of LiFePO4/ccomposites is governed by pH value.
Bicyclol is a synthetic drug for hepatoprotection in clinic since 2004. Preliminary clinical observations suggest that bicyclol might be active against hepatitis c virus(HcV) with unknown mechanism. Here, we showed th...
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Bicyclol is a synthetic drug for hepatoprotection in clinic since 2004. Preliminary clinical observations suggest that bicyclol might be active against hepatitis c virus(HcV) with unknown mechanism. Here, we showed that bicyclol significantly inhibited HcV replication in vitro and in hepatitis c patients. Using bicyclol as a probe, we identified glycolipid transfer protein(GLTP) to be a novel restrictive factor for HcV replication. The GLTP preferentially bound host vesicle-associated membrane protein-associated protein-A(VAP-A) in competition with the HcV NS5 A, causing an interruption of the complex formation between VAP-A and HcV NS5 A. As the formation of VAP-A/NS5 A complex is essential for viral RNA replication, up-regulation of GLTP by bicyclol reduced the level of VAP-A/NS5 A complex and thus inhibited HcV replication. Bicyclol also exhibited an inhibition on HcV variants resistant to direct-acting antiviral agents(DAAs) with an efficacy identical to that on wild type HcV. In combination with bicyclol, DAAs inhibited HcV replication in a synergistic fashion. GLTP appears to be a newly discovered host restrictive factor for HcV replication, Up-regulation of GLTP causes spontaneous restriction of HcV replication.
In this study, an efficient HPLc method was developed and validated to determine seven polyphenols, i.e. chlorogenic acid, caffeic acid, protocatechuic acid, geniposide, rutin, quercetin and isorhamnetin, in different...
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In this study, an efficient HPLc method was developed and validated to determine seven polyphenols, i.e. chlorogenic acid, caffeic acid, protocatechuic acid, geniposide, rutin, quercetin and isorhamnetin, in different parts (leaves, barks and fruits) of Eucommia ulmoides. A Luna c-18 column (150 mm x 3.9 mm, 5.0 mu m) was applied and eluted with a gradient of acetonitrile-modified aqueous mobile phase (containing 1% acetic acid). 260 nm, 326 nm, and 360 nm were used as the detection wavelengths. With the developed method, these seven polyphenols were successfully assayed and their contents in different parts of E. ulmoides were compared. The results showed that these polyphenols displayed different distribution in the leaves, barks and fruits. chlorogenic acid, caffeic acid and rutin were their main common constituents. ABTS and DPPH free radical scavenging assay indicated that E. ulmoides displayed significant antioxidant activities in vitro. In addition, the extracts of the three parts can significantly increase the anti-oxidative stress level in wild-type c. elegans and prolong its lifespan, further demonstrating the antioxidant activity of Eucommia ulmoides.
Fullerene based electronic devices are gathering much attention due to their excellent properties. Among many of the carbon fullerenes available, ‘c 20 ′ is so far the smallest fullerene of carbon. c 20 structure is...
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Fullerene based electronic devices are gathering much attention due to their excellent properties. Among many of the carbon fullerenes available, ‘c 20 ′ is so far the smallest fullerene of carbon. c 20 structure is like a polyhedral cage having 30 edges with zero (n-2/10) hexagons and twelve pentagons. It is the only known fullerene smaller than c 60 with full Ih symmetry. Even though it is a small molecule it has extraordinary properties which make it fit for usage in various applications as it has NDR behavior, it can bind with proteins and most importantly is coherent and reliable. It is utilized in applications like organic solar cells, creation of hybrid materials and in various sensing applications. Although a lot of research is ongoing on c 20 , yet further research is required to get more insights into its properties. Therefore, this paper contains detailed review on c 20 fullerene and future research prospects.
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