•The dynamic response of Hastelloy® X plates subjected to normal and oblique shock loading was studied.•Experimental investigation was carried out using a shock tube and the out-of-plane deformation ...was obtained with 3D DIC technique.•Numerical simulations were performed in a fully coupled Eulerian–Lagrangian method using DYSMAS.•Lower angles of shock incidence caused more deformation on the specimens.
The dynamic behavior of Hastelloy® X plates subjected to normal and oblique shock loading was studied both experimentally and numerically. A series of experiments was conducted on Hastelloy® X plates at room temperature under fixed boundary conditions using a shock tube apparatus. High-speed digital cameras were used to obtain the real-time images of the specimen during the shock loading. Digital image correlation (DIC) technique was utilized to obtain 3D deformations of the plates using stereo-images of the specimen. The numerical modeling utilized the finite element software package Dynamic System Mechanics Analysis Simulation (DYSMAS), which includes both the structural analysis as well as the fluid–structure interaction to study the dynamic behavior of the specimen under given loads. Experimentally obtained pressure–time profiles were used as a reference in numerical modeling. It was observed that the lower angles of shock incidence caused more deformation on the specimen. Additionally for oblique shocked specimens, the deformation was observed to initiate from the edge nearer to the muzzle. The results from the numerical simulations were validated with the experimental data, and showed excellent correlation for all cases.
Generation of a quasi-mono-energetic electron beam with peak energy ~3 MeV and full cone divergence angle of ~3° is observed in the interaction of 45 fs, 3 TW Ti:sapphire laser beam incident on a ...planar carbon target surface at grazing incidence. The collimated and quasi-mono-energetic electron beam was observed when a pre-pulse pedestal of 1-ns duration was used with the main 45-fs laser pulse. The study presented on generation of spatially and spectrally concentrated multi-MeV electron beam along solid target surface could be of significance for current areas of research like fast ignition scheme of inertial confinement fusion.
This paper presents the synthesizing of carbon-carbon (CC) composites by preformed yarn (PY) method, by varying the percentage of carbon fiber volume. The PY used is carbon fiber bundle surrounded by ...coke and pitch which is enclosed in nylon-6. Three types of samples with fiber weight fractions of 30%, 40% and 50% respectively, are fabricated and tested. In each case, the PY is chopped and filled into a die of required shape and hot pressed at 600°C to get the carbonized composite. To obtain the graphitic structure, the specimen is heat treated at 1800°C followed by soaking for two hours. Further, one cycle pitch impregnation is done by hot isostatic pressing, to eliminate the voids. The characteristics such as hardness, compressive strength, creep, density and oxidation resistance are studied. It is observed that, as the carbon fiber percentage increases the properties also improved, provided sintering is done at fairly higher temperatures. The superiority of the new class of CC composites made by the proposed PY technique over those obtained by the conventional methods is also demonstrated.
Background: Aflatoxicosis in ducks is reckoned as a challenge for nutritionists worldwide, for its adverse impacts on growth. A study was conducted to ascertain the precise level of ...Aflatoxin-tolerance in White Pekin ducklings during juvenile ages.
Methods: Day-old-ducklings (240) were randomly distributed into 3 experimental-groups viz., Control ( less than 0.5 ppb), T1 (200 ppb), T2 (400 ppb) and reared for measuring weekly growth, feed efficiency and blood biochemical changes, with treatments terminated at 6weeks age.
Result: There was significant depression in live weights for both dietary-toxin groups from 2nd week onwards till completion. Mortality (0-6 weeks) was 85% in T2, while T1 was in between control and T2, both for mortality (45%) and morbidity. Feed-consumption and conversion for either toxin groups remained significantly (p≤0.05) poor, with T2 resulting in erratic FCRs, ranging from 1.23 to 4.95, across weeks. A typical AFB1-induced lameness in ducklings beyond 3 weeks of AFB1-exposure, emerged as a hallmarked morbidity, in varied proportions, in T1 and T2, but not in control. The study confirms that acute-depression of juvenile growth and high-morbidity are distinct outcomes from AFB1’s presence in Pekin diets @ 200 ppb level or higher, with such leg deformities emerging as hallmarked features of Pekins reared on AFB1-spiked diets. It can be concluded that, while the AFB1 content of juvenile White Pekin ducks should be kept limited to the recommended safe levels ( less than 10 ppb); exceeding a threshold of 200 ppb is sure to cause poor growth and FCR, with adverse blood biochemical changes, high mortality, morbidity and lameness.
Platelet activation by ITAM receptors contributes to hemostasis, thrombosis, vascular integrity and host defense. In the course of our studies of FcγRIIA-mediated platelet activation, we became ...interested in those mechanisms that require neither full Syk activation nor changes in intracellular calcium. Calcium-independent phospholipase family member iPLA2β has been observed to modulate phospholipid remodeling and second messenger generation in human platelets (Beckett, Thromb Res 2007; Duvernay, Biochem 2015), while iPLA2γ has been studied in knockout mouse platelets (Yoda, JTH 2014) with modest effects noted on thrombosis and hemostasis. These enzymes do not require increased cytoplasmic calcium for their activity in cleaving the acyl group from the sn2 position of phospholipids to yield a free fatty acid and a lysophospholipid. However, the precise role of iPLA2β in human and mouse platelet activation has not been elucidated. Neither has the contribution of iPLA2β in the response to FcγRIIA-mediated activation been reported.
We identified the presence of iPLA2β protein in western blots of human and FcγRIIA transgenic mouse platelets. Of interest, multiple isoforms arising from proteolytic cleavage were detected. We treated washed human and FcγRIIA transgenic mouse platelets with agonists to FcγRIIA (IV.3 + GAM) and to GPVI (collagen or collagen-related peptide) in the absence and presence of pharmacologic inhibitors of iPLA2β. At a range of agonist doses up to 3X threshold, we observed significant inhibition of aggregation, dense granule secretion and alpha granule secretion (p<0.05 vs. vehicle only, n = 3 to 4 each). Inhibition occurred with either S-BEL (bromo-enolactone) or with FKGK18 (a fluoroketone), two chemically distinct iPLA2β inhibitor molecules with different modes of action. The IC50 for S-BEL was found to be 1.02 uM for human FcγRIIA, 2.04 uM for human GPVI, and 2.76 uM for transgenic mouse FcγRIIA activated platelets. FKGK18 was less potent, with IC50s at 7.88 uM for human FcγRIIA. In contrast, iPLA2γ inhibitor R-BEL was able to inhibit FcγRIIA -mediated activation, but at an IC50 of 2.62 uM. Notably, iPLA2β inhibition could eliminate ATP secretion from dense granules downstream of FcγRIIA and GPVI activation. When we added ADP to FcγRIIA stimulation in the presence of inhibitory doses of S-BEL, we overcame the inhibition.
We have identified for the first time that iPLA2β contributes to aggregation and secretion of both human and FcγRIIA transgenic mouse platelets. The platelets were slightly more sensitive to FcγRIIA than to GPVI inhibition. In other activatable secretory cells, iPLA2β plays both a homeostatic and signaling role. The mechanisms of iPLA2β action in platelets merit further study. Studies are in progress with genetic knockdown and knockout of the enzyme, to complement the findings with inhibitors.
No relevant conflicts of interest to declare.
The clinical significance of the interaction of antibodies with circulating platelets is well documented, but the mechanisms underlying these interactions are not fully known. Here we describe the ...characterization of anti-human platelet membrane protein monoclonal antibody (mAb) termed F11. Interaction of mAb F11 with human platelets resulted in dose-dependent granular secretion, measured by 14Cserotonin and ATP release, fibrinogen binding and aggregation. Analysis of the specific binding of mAb F11 to platelets revealed a high affinity site with 8,067 +/- 1,307 sites per platelet with a dissociation constant (Kd) of 2.7 +/- 0.9 x 10(-8) M. Two membrane proteins of 32,000 and 35,000 daltons, identified by Western blotting, were recognized by mAb F11. Incubation of 32Pi-labeled platelets with mAb F11 resulted in rapid phosphorylation of intracellular 40,000- and 20,000-dalton proteins, followed by dephosphorylation of these proteins. Monovalent Fab fragments or Fc fragments of mAb F11 IgG did not induce platelet aggregation or secretion; however, Fab fragments of mAb F11 IgG blocked mAb F11-induced platelet aggregation and the binding of 125I-mAb F11 to platelets. The addition of an anti-GPIIIa monoclonal antibody (mAb G10), which inhibits 125I-fibrinogen binding and platelet aggregation, completely blocked mAb F11-induced 14Cserotonin secretion and aggregation but not the binding of 125I-mAb F11 to platelets. mAb G10 also inhibited the increase in the phosphorylation of the 40,000- and 20,000-dalton proteins induced by mAb F11. These results implicate the involvement of the GPIIIa molecule in the chain of biochemical events involved in the induction of granular secretion.
Efficacy of silver thiosulfate (STS) in reducing ethylene-induced culture abnormalities during minimal growth conservation of microplants was studied in seven potato (Solanum tuberosum L.) genotypes. ...Different concentrations of STS (0, 1.5, 3.0, 4.5, 6.0, 7.5 and 9.0 micrograms ml(-1)) were tested in minimal growth medium based on MS medium supplemented with 20 g l(-1) mannitol and 40 g l(-1) sucrose. STS improved the microplant growth and reduced the culture abnormalities during prolonged maintenance of potato shoot cultures in vitro. The beneficial effect of STS was most prominent for number of green leaves per microplant and leaf senescence. After 16 months of storage, desirable microplant growth was observed in cultures conserved in medium containing 6.0-9.0 micrograms ml(-1) STS. The profile of the peroxidase isozymes of conserved cultures did not show any apparent genetic variation due to the presence of STS in the conservation medium.
Retailers did not immediately extend their business to the Internet environment, fearing that on-line activities could adversely impact their off-line sales. To facilitate assessment of the impact of ...on-line activities on offline sales, we develop a method that allows retailers to use readily available market data for making informed decisions. The proposed method determines (1) the extent to which on-line sales cannibalize off- line sales, and (2) whether on-line activities build on-line equity for the firm. We illustrate the method using data from Tower Records' Internet sales division. We find that on-line sales do not significantly cannibalize retail sales and that the firm's web activities build long-term on- line equity. While the proposed method can be used by any "clicks-and-mortar" firm, our firm-specific results indicate that Towers' fears regarding cannibalization due to its own Internet activities were unfounded.
Rare earth (Nd3+) doped Manganese-Zinc Ferrite nanoparticles with composition Mn0.65Zn0.35Fe2-xNdxO4 (x = 0.04, 0.05 and 0.06) were prepared using combustion method of materials preparation. ...Formation of pure spinel phase was confirmed using X-ray diffraction (XRD) and Fourier transforms infra red spectroscopy (FTIR). The samples were exposed to various doses of y-radiation (500Gy, 750Gy and 1000Gy) after recording the data on structural and electrical transport properties of as prepared samples, in order to study the effect of y-radiation on these properties of the nanoparticles. Lattice constant 'a' that showed a moderate increment with Nd3+ doping was found to show a further increase after y-radiation exposure with nearly a 30%-40% reduction in crystallite size. Transmission electron micrographs showed a decreasing trend of particle size that was nearly proportional to increasing dose of y-radiation. The samples which showed enhancement in resistivity profile with increasing Nd3+ concentration showed a reverse trend of decrease in the resistivity values with increasing y radiation dose thus contributing to the conduction process. The dielectric constant of Nd3+ doped samples showed a multifold increase in the dielectric constant with a further increase in its values for radiated samples, when referred to the values reported for undoped Mn-Zn nanoparticle ferrite materials.
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