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111.
Alain A Camilleri Raffaella Willmann Gayathri Sadasivam Shuo Lin Markus A Rüegg Matthias Gesemann Christian Fuhrer 《BMC neuroscience》2007,8(1):46
Background
Development of neural networks requires that synapses are formed, eliminated and stabilized. At the neuromuscular junction (NMJ), agrin/MuSK signaling, by triggering downstream pathways, causes clustering and phosphorylation of postsynaptic acetylcholine receptors (AChRs). Postnatally, AChR aggregates are stabilized by molecular pathways that are poorly characterized. Gain or loss of function of Src-family kinases (SFKs) disassembles AChR clusters at adult NMJs in vivo, whereas AChR aggregates disperse rapidly upon withdrawal of agrin from cultured src -/-;fyn -/- myotubes. This suggests that a balance between protein tyrosine phosphatases (PTPs) and protein tyrosine kinases (PTKs) such as those of the Src-family may be essential in stabilizing clusters of AChRs. 相似文献112.
N. Naveen Kumar R. Tewari P. Mukherjee N. Gayathri P. V. Durgaprasad G. S. Taki 《辐射效应与固体损伤》2017,172(7-8):678-694
In the present study, microstructures of Ferritic-martensitic T-91 steel irradiated at room temperature for 5, 10 and 20?dpa using 315?KeV Ar+9 ions have been characterized by grazing incident X-ray diffraction (GIXRD) and by transmission electron microscopy (TEM). Line profiles of GIXRD patterns have shown that the size of domain continuously reduced with increasing dose of radiation. TEM investigations of irradiated samples have shown the presence of black dots, the number density of which decreases with increasing dose. Microstructures of irradiated samples have also revealed the presence of point defect clusters, such as dislocation loops and bubbles. In addition, dissolution of precipitates due to irradiation was also observed. Nano-indentation studies on the irradiated samples have shown saturation behavior in hardness as a function of dose which could be correlated with the changes in the yield strength of the alloy. 相似文献
113.
Gold(I) thiolate compounds (i.e. AuI-SR) are important precursors for the synthesis of atomically precise Aun(SR)m nanoclusters. However, the nature of the AuI-SR precursor remains elusive. Here, we report that the Au10(TBBT)10 complex is a universal precursor for the synthesis of Aun(TBBT)m nanoclusters (where TBBT=4-tertbutylbenzenethiol/thiolate). Interestingly, the Au10(TBBT)10 complex is also found to be re-generated through extended etching of the Aun(SR)m nanoclusters with excess of TBBT thiol and O2. The formation of well-defined Au10(TBBT)10 complex, instead of polymeric AuI-SR, is attributed to the bulkiness of the TBBT thiol. Through 1D and 2D NMR characterization, the structure of Au10(TBBT)10 is correlated with the previously reported X-ray structure, which contains two inter-penetrated Au5(TBBT)5 rings. The photophysical property of Au10(TBBT)10 complex is further probed by femtosecond transient absorption spectroscopy. The accessibility of the precise Au10(TBBT)10 precursor improves the efficiency of the synthesis of the Aun(TBBT)m nanoclusters and is expected to further facilitate excellent control and understanding of the reaction mechanisms of nanocluster synthesis. 相似文献
114.
A ditopic receptor is shown to have an impressive ability to recognize and extract the ion pairs of various alkali halides into organic solution. X-ray diffraction analysis indicates that the salts are bound in the solid state as contact ion pairs. Transport experiments, using a supported liquid membrane and high salt concentration in the source phase, show that the ditopic receptor can transport alkali halide salts up to 10-fold faster than a monotopic cation or anion receptor and 2-fold faster than a binary mixture of cation and anion receptors. All transport systems exhibit the same qualitative order of ion selectivity; that is, for a constant anion, the cation selectivity order is K+ > Na+ > Li+, and for a constant cation, the anion transport selectivity order is I- > Br- > Cl-. The data suggest that with a ditopic receptor, the polarity of the receptor-salt complex can be lowered if the salt is bound as an associated ion pair, which leads to a faster diffusion through the membrane and a higher maximal flux. 相似文献
115.
Riveira MJ Gayathri C Navarro-Vázquez A Tsarevsky NV Gil RR Mischne MP 《Organic & biomolecular chemistry》2011,9(9):3170-3175
A new approach to the synthesis of cyclopenta[b]benzofuran derivatives via reaction of 1,3-dicarbonyl compounds with α,β,γ,δ-unsaturated aldehydes is described. The constitution and configuration of the new products have been firmly established by means of residual dipolar couplings (RDCs) and ab initio (13)C NMR chemical shift predictions. 相似文献
116.
Recently there has been lot of interest in the development of hydrogen storage in various systems for the large-scale application
of fuel cells, mobiles and for automotive uses. Hectic materials research is going on throughout the world with various adsorption
mechanisms to increase the storage capacity. It was observed that physisorption proves to be an effective way for this purpose.
Some of the materials in this race include graphite, zeolite, carbon fibers and nanotubes. Among all these, the versatile
material carbon nanotube (CNT) has a number of favorable points like porous nature, high surface area, hollowness, high stability
and light weight, which facilitate the hydrogen adsorption in both outer and inner portions. In this work we have considered
armchair (5,5), zig zag (10,0) and chiral tubes (8,2) and (6,4) with and without structural defects to study the physisorption
of hydrogen on the surface of carbon nanotubes using DFT calculations. For two different H2 configurations, adsorption binding energies are estimated both for defect free and defected carbon nanotubes. We could observe
larger adsorption energies for the configuration in which the hydrogen molecular axis perpendicular to the hexagonal carbon
ring than for parallel to C–C bond configuration corresponding to the defect free nanotubes. For defected tubes the adsorption
energies are calculated for various configurations such as molecular axis perpendicular to a defect site octagon and parallel
to C–C bond of octagon and another case where the axis perpendicular to hexagon in defected tube. The adsorption binding energy
values are compared with defect free case. The results are discussed in detail for hydrogen storage applications. 相似文献
117.
Rajeswari Gopal Geetha Sivakumar Krishnankutty Nair Chandrika Gayathri G. Saraswathy Asha Nair Sivakumari Manjula Sakuntala 《Molecules (Basel, Switzerland)》2021,26(8)
Osmotin, a plant defense protein, has functional similarity to adiponectin, an insulin sensitizingsensitising hormone secreted by adipocytes. We speculated that Piper colubrinum Osmotin (PcOSM) could have functional roles in obesity-related cancers, especially breast cancer. Immunofluorescence assays, flow cytometry, cell cycle analysis and a senescence assay were employed to delineate the activity in MDAMB231 breast cancer cell line. PcOSM pre-treated P. nigrum leaves showed significant reduction in disease symptoms correlated with high ROS production. In silico analysis predicted that PcOSM has higher binding efficiency with adiponectin receptor compared to adiponectin. PcOSM was effectively taken up by MDAMB231 cancer cells which resulted in marked increase in intracellular ROS levels leading to senescence and cell cycle arrest in G2/M stage. This study provides evidence on the ROS mediated direct inhibitory activity of the plant derived osmotin protein on the phytopathogen Phytophthora capsici, and the additional functional roles of this plant defense protein on cancer cells through inducing ROS associated senescence. The strong leads produced from this study could be pursued further to obtain more insights into the therapeutic potential of osmotin in human cancers. 相似文献
118.
N. Kanagathara M. K. Marchewka N. Sivakumar K. Gayathri N. G. Renganathan S. Gunasekaran G. Anbalagan 《Journal of Thermal Analysis and Calorimetry》2013,112(3):1317-1323
Single crystals of melaminium perchlorate monohydrate (MPM) have been grown from aqueous solution by slow solvent evaporation method at room temperature. X-ray powder diffraction analysis confirms the title crystal crystallizes in the triclinic (P-1) structure and the calculated lattice parameters are a = 5.6275 ± 0.0780 Å, b = 7.6926 ± 0.1025 Å, c = 12.0878 ± 0.2756 Å, α = 103.89 ± 1.01°, β = 94.61 ± 0.92°, γ = 110.22 ± 0.81°, and V = 468.95 Å3. The thermal decomposition behavior of MPM has been studied by means of thermogravimetric analysis at three different heating rates 5, 10, and 20 °C min?1. The values of effective activation energy (E a), pre-exponential factor (ln A) of each stage of thermal decomposition for all heating rates were calculated by model free method: Kissinger, Kim–Park, and Flynn–Wall method. A significant variation of effective activation energy (E a) with conversion (α) indicates that the process is kinetically complex. The linear relationship between the A and E a values was established (compensation effect). Dielectric study has also been carried out and it is found that both dielectric constant (ε′) and dielectric loss (ε″) decreases with increase in frequency. 相似文献
119.
Gayathri Swaminathan Kirti Chandra Sahu A. Sameen Rama Govindarajan 《Theoretical and Computational Fluid Dynamics》2011,25(1-4):53-64
A global stability study of a divergent channel flow reveals features not obtained hitherto by making either the parallel or the weakly non-parallel (WNP) flow assumption. A divergent channel flow is chosen for this study since it is the simplest spatially developing flow: the Reynolds number is constant downstream, and for a theoretical Jeffery?CHamel flow, the velocity profile obeys similarity. Even in this simple flow, the global modes are shown to be qualitatively different from the parallel or WNP. In particular, the disturbance modes are often not wave-like, and the local scale, estimated from a wavelet analysis, can be a function of both streamwise and normal coordinates. The streamwise variation of the scales is often very different from the expected linear variation. Given recent global stability studies on boundary layers, such spatially extended modes which are not wave-like are unexpected. A scaling argument for why the critical Reynolds number is so sensitive to divergence is offered. 相似文献