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121.
Dissimilarity in the oxidative folding of onconase and ribonuclease A, two structural homologues 总被引:1,自引:0,他引:1
Gahl RF Narayan M Xu G Scheraga HA 《Protein engineering, design & selection : PEDS》2008,21(4):223-231
The oxidative folding of frog onconase (ONC), a member of theribonuclease A family, was examined and shows markedly differentbehavior compared to its structural homologue bovine pancreaticribonuclease A (RNase A) under similar conditions. Applicationof a reduction pulse (using a small amount of reduced dithiothreitol)during the oxidative regeneration of ONC indicated the survivalof the native protein along with three other (structured) species,I1, I2 and I3, with the rest of the unstructured species beingconverted to fully reduced protein. Mass spectrometry indicatesthat I1 has two disulfide bonds, whereas I2 and I3 have threedisulfide bonds each. A disulfide mapping method, based on cyanylation,was used to identify I2 and I3 as des-[30–75] and des-[19–68],respectively. On enzymatic digestion using trypsin, I1 was identifiedas des-[19–68, 30–75]. Differences in the intermediatesthat are generated during the oxidative folding of the two structuralhomologues, RNase A and ONC, demonstrate that regenerative pathwaysare not necessarily influenced by tertiary structure. This indicatesthat the lack of a disulfide bond in ONC, analogous to the (65–72)disulfide bond in RNase A which plays an important role in itsoxidative regeneration, does not adversely affect the oxidativefolding of ONC. 相似文献
122.
Rani MP Krishna MS Padmakumari KP Raghu KG Sundaresan A 《Journal of the science of food and agriculture》2012,92(9):1948-1955
BACKGROUND: Ginger, the rhizome of Zingiber officinale Roscoe (Zingiberaceae), a perennial herbaceous plant is native to Southern Asia. Study was aimed to evaluate antioxidant and antidiabetic potential of ginger extract and its characterization. Possible mode of action to elicit antidiabetic activity was also evaluated. METHODS AND RESULTS: Ethyl acetate extract of ginger (EAG) was evaluated for its antioxidant activity in terms of DPPH radical scavenging potential with an IC50 value of 4.59 µg/ml. Antidiabetic activity of EAG was evaluated by estimating antiglycation potential (IC50 290.84 µg/ml). HPLC profiling of EAG revealed the presence of phenolic components, gingerol and shoagol as major constituents. After determining sub‐toxic concentration of EAG (50 µg/ml), efficacy of extract to enhance glucose uptake in cell lines were checked in L6 mouse myoblast and myotubes. EAG was effective at 5 µg/ml concentration in both cases. Antibody based studies in treated cells revealed the effect of EAG in expressing Glut 4 in cell surface membrane compared to control. CONCLUSION: The antidiabetic effect of ginger was experimentally proved in the study and has concluded that the activity is initiated by antioxidant, antiglycation and potential to express or transport Glut4 receptors from internal vesicles. Copyright © 2012 Society of Chemical Industry 相似文献
123.
R. Devesh K. Misra Bhupendra Girase Pavan K. C. Venkata Surya Mahesh C. Somani L. Pentti Karjalainen 《Advanced Engineering Materials》2011,13(12):B483-B492
We elucidate here the fundamental principles underlying the modulation of osteoblasts functions in stainless steel biomedical devices achieved by nanoscale/submicron grain structure obtained through the novel concept of phase reversion in a low Ni bearing 15Cr–9Mn–1.7Cu steel. Interestingly, a comparative investigation of nano/submicron (N‐SM) and coarse‐grained (CG) structure under identical conditions indicated that cell attachment, proliferation, and viability are favorably enhanced in N‐SM grained structure and significantly different from the CG structure. These observations were further confirmed by expression levels of vinculin and associated actin cytoskeleton. Computational analysis of immunofluorescence micrographs suggested increased vinculin concentration associated with actin stress fibers in the outer regions of the cells and cellular extensions, implying enhanced cell–substrate interactions on the N‐SM grained substrate. The favorable enhancement of osteoblasts functions and cellular attachment on N‐SM grained surface is attributed to ultrafine grain size, i.e., the availability of greater open lattice in the position of high angle grain boundaries, and high hydrophilicity. The integration of cellular and molecular biology with material science and engineering as described here provides a route to modulate cellular and molecular reactions in promoting osteoinductive signaling of surface adherent cells. The end outcome of the study is that stainless steels with low Ni contents in comparison to the conventionally used bioimplant with 10–13 wt%Ni, as specially processed, exhibit desired, enhanced cell functions, and bulk properties. 相似文献
124.
The comparative performance of photogalvanic cells has been studied for solar energy conversion and storage by using Methyl Orange, Rose Bengal, Toluidine Blue and Brilliant Cresyl Blue as different photosensitizers with d-Xylose as reductant and Sodium Lauryl Sulphate (NaLS) as surfactant in the different systems. The photogeneration of photopotential are 890.0, 885.0, 945.0 and 940.0 mV whereas the maximum photocurrent is 625.0, 575.0, 510.0 and 480.0 μA, respectively. The short circuit current or photocurrent at equilibrium is 480.0, 460.0, 430.0 and 440.0 μA, respectively. The observed conversion efficiencies for Methyl Orange, Rose Bengal, Toluidine Blue and Brilliant Cresyl Blue with d-Xylose and Sodium Lauryl Sulphate systems are 1.6245, 1.5261, 1.4323 and 1.1057%, respectively. The fill factors 0.3244, 0.3151, 0.3120, and 0.2408 are experimentally determined at the power point of the cell where the absolute value is 1.0. The photogalvanic cells so developed can work for 160.0, 145.0, 130.0 and 140.0 min in dark if it is irradiated for 180.0, 165.0, 135.0 and 150.0 min, respectively where the percentage of storage capacity of photogalvanic cells are found 87.87%-96.29%. All observed results are the higher among the reported results so far in the literature. 相似文献
125.
Rob van Haaren Mahesh Morjaria Vasilis Fthenakis 《Progress in Photovoltaics: Research and Applications》2014,22(5):548-559
Variability of solar power is a key driver in increasing the cost of integrating solar power into the electric grid because additional system resources are required to maintain the grid's reliability. In this study, we characterize the variability in power output of six photovoltaic plants in the USA and Canada with a total installed capacity of 195 MW (AC); it is based on minute‐averaged data from each plant and the output from 390 inverters. We use a simple metric, “daily aggregate ramp rate” to quantify, categorize, and compare daily variability across these multiple sites. With this metric, the effect of geographic dispersion is observed, while controlling for climatic differences across the plants. Additionally, we characterized variability due to geographical dispersion by simulating a step by step increase of the plant size at the same location. We observed maximum ramp rates for 5, 21, 48, and 80 MWAC plants, respectively, as 0.7, 0.58, 0.53, and 0.43 times the plant's capacity. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
126.
Medury D. Sastry Mahesh P. GaonkarYogesh C. Nagar Sandesh N. ManeShripal N. Desai H. BaglaK.T. Ramachandran Ashok K. Singhvi 《Diamond and Related Materials》2011,20(8):1095-1102
We report the first optically stimulated luminescence (OSL; blue light stimulated luminescence (BLSL) and infrared light stimulated luminescence (IRSL)) results on colored diamonds and present experimental evidence that electron beam treatment (EBT) increases the radiation sensitivity of diamonds to a level that makes them suitable for low level radiation dosimetry. A suite of seven samples was examined. These comprise a white, three brown and three yellow diamond pieces. The FT-IR spectra of these diamonds revealed the nature and concentration of nitrogen impurity. The white diamond was kept as a control. The brown and yellow (with varied saturation) diamonds were irradiated by a 1.7 MeV electron beam. These turned blue/dark green; three of them were then heated in vacuum in the temperature range of 850-900 °C for two hours. Heating turned the irradiated diamonds to lemon yellow, pink, and purple colors. The irradiated and unheated blue samples were designated as 2C and 2D.The control sample, an un-irradiated white type Ia diamond, did not yield any significant IRSL/BLSL with doses up to 100 Gy. The BLSL/IRSL sensitivity of irradiated and heat treated diamonds was very poor, and depended on the heat cycle and hence were not pursued. Sample 2C exhibited significant BLSL and negligible IRSL sensitivity. Sample 2D gave an intense orange red emission under IR excitation as also responded to BLSL. The dose response of the BLSL signal in 2C suggested a minimum detectable dose of ~ 0.1 Gy and its use as a tissue equivalent dosimeter.Based on supporting experiments such as laser excited photoluminescence, we suggest that the BLSL process in 2C is primarily driven by carbon vacancies, which release a mobile hole when excited by GR2 band in the blue region. BLSL intensity exhibited a maximum around 285 °C. Given that TL glow peak also occurs near this temperature and that the nitrogen-interstitial carbon (N-Ci) complex also forms at this temperature (as reported in the literature), and it appears that the e-h recombination at sites with N-Ci complex could be involved in BLSL production. Laser excited photoluminescence (PL) at wavelengths 325, 514 and 785 nm and absorption spectra in UV-Visible range gave insights into the contrasting BLSL/IRSL responses of 2C and 2D. These differences were due to differences in nitrogen impurity complexes and the concentration of carbon vacancies produced by EBT in 2C and 2D. In 2D, the presence of Ni as NE8 center (four nitrogens coordinated to Ni) giving 800 nm emission on 785 nm excitation, appeared to suppress BLSL and sensitize IRSL in the orange window. 相似文献
127.
In this work, we report a basic study on the mechanism of lithium ion de-insertion/insertion process from/into LiMn2O4 cathode material in aqueous Li2SO4 solution using electrochemical impedance spectroscopy (EIS). An equivalent circuit distinguishing the kinetic parameters of lithium ion de-insertion/insertion is used to simulate the experimental impedance data. The fitting results are in good agreement with the experimental results and the parameters of the kinetic process of Li+ de-insertion and insertion in LiMn2O4 at different potentials during charge and discharge are obtained using the same circuit. The results indicate that the de-insertion/insertion behavior of lithium ions at LiMn2O4 cathode in Li2SO4 aqueous solution is similar to that reported in the organic electrolytes. The charge transfer resistance (Rct), warburg resistance, double layer capacitance and chemical diffusion coefficient (DLi+) vary with potentials during de-insertion/insertion processes. Rct is lowest at the CV peak potentials and the important kinetic parameter, DLi+ exhibits two distinct minima at potentials corresponding to CV peaks during de-insertion–insertion and it was found to be between 10−8 and 10−10 cm2 s−1during lithium de-insertion/insertion processes. 相似文献
128.
Development of alternate materials to Nafion, based on ionically conducting polymers and their blends is important for the wider applications of proton exchange membrane fuel cells. In this work, blends of sulfonated poly(ether ether ketone) (SPEEK) with poly(ether sulfone) (PES) are investigated. SPEEK with various ion exchange capacity (IEC) was prepared and blended with PES, which is nonionic and hydrophobic in nature. A comparative study of the water uptake, proton conductivity, and thermo‐mechanical characteristics of SPEEK and the blend membranes as a function of the IEC is presented. Addition of PES decreases the water uptake and conductivity of SPEEK. Chemical and thermal stability and mechanical properties of the membrane improve with the addition of PES. The effect of water content on the thermo‐mechanical properties of membranes was also studied. The morphology of blend membranes was studied using SEM to understand the microstructure and miscibility of the components. On the basis of the results, a plausible microstructure of the blends is presented, and is shown to be useful in understanding the variation of different properties with blending. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
129.
The extremely fine grain size of nanocrystalline (nc) metallic alloys results in significantly different mechanical, electrochemical and oxidation properties as compared to the coarse-grained alloys of the same composition. Although the synthesis and attractive mechanical properties of nanocrystalline materials have been investigated and reviewed in great depth, the high temperature oxidation and electrochemical corrosion of these materials has received limited attention. The difference in the active dissolution and passivation behavior of nc alloys as compared to their microcrystalline counterparts varies for each alloy system. However, a unified theory explaining these phenomena still eludes us. In this context, this article reviews the progress in the electrochemical corrosion behavior of different nanocrystalline alloys, and hence, develops a better understanding of the effect of grain size, composition, interfacial phenomena and selective dissolution on corrosion of nanocrystalline alloys. This review also presents the role of nanometric grain size and the associated increase in grain boundary diffusion on the high temperature oxidation of nc alloys. The attractive possibility of enhanced oxidation resistance at lower alloying additions as compared to the coarse-grained alloys has been discussed. Although the primary focus of the article is on ferrous alloy systems, however, the lead studies on the role of ultrafine grain size in oxidation/corrosion behavior of other alloys systems have also been reviewed. 相似文献
130.
The Internet now-a-days has become indispensable to each and everyone. It is vulnerable to node failures, link failures, and fluctuations due to many known or unknown reasons in the network connectivity. The bitter truth is even today networks’ failure, link faults are happening. A single change in a link or a node has a potential to trigger the unstable-routing-tables of many nodes. These failures may lead the network in an unstable state by increasing its convergence time significantly longer. In this paper we propose an algorithm to keep the value of the minimum route advertisement interval timer variable unlike the conventional approach of keeping it constant. The proposed approach makes the timer value varying depending on the receiver’s position with respect to the origin of the prefix advertised on the network. Simulations’ results show that the convergence time becomes significantly low and make the network converge relatively quicker. 相似文献