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排序方式: 共有239条查询结果,搜索用时 15 毫秒
231.
S Koppula H Kumar SV More BW Kim IS Kim DK Choi 《International journal of molecular sciences》2012,13(8):10608-10629
Parkinson's disease (PD), a neurodegenerative movement disorder of the central nervous system (CNS) is characterized by a progressive loss of dopaminergic neurons in the substantia nigra pars compacta region of the midbrain. Although the etiology of PD is not completely understood and is believed to be multifactorial, oxidative stress and mitochondrial dysfunction are widely considered major consequences, which provide important clues to the disease mechanisms. Studies have explored the role of free radicals and oxidative stress that contributes to the cascade of events leading to dopamine cell degeneration in PD. In general, in-built protective mechanisms consisting of enzymatic and non-enzymatic antioxidants in the CNS play decisive roles in preventing neuronal cell loss due to free radicals. But the ability to produce these antioxidants decreases with aging. Therefore, antioxidant therapy alone or in combination with current treatment methods may represent an attractive strategy for treating or preventing the neurodegeneration seen in PD. Here we summarize the recent discoveries of potential antioxidant compounds for modulating free radical mediated oxidative stress leading to neurotoxicity in PD. 相似文献
232.
Heat shock proteins and RNA polymerase sigma factor play an important role in protecting cells against environmental stresses, including starvation, osmotic and oxidative stresses, and cold shock. In this study, the effect of environmental stresses on activity of the auto-fluorescent Escherichia coli O157:H7 generated by the fusion of gfp(uv) to E. coli uspA, grpE and rpoS promoters were examined. Osmotic shock caused about a 4-fold increase in green fluorescence of E. coli O157:H7 harboring uspA::gfp(uv) or rpoS::gfp(uv) at 37 degrees C and room temperature whereas osmotic shock at 5 degrees C did not induce green fluorescence. When starved, E. coli O157:H7 possessing grpE::gfp(uv) was more sensitive for evaluating stress at low temperature while uspA::gfp(uv) was better suited for detecting the stress response at higher temperature. The uspA, grpE and rpoS promoters were up-regulated to varying degrees by stresses commonly encountered during food processing. 相似文献
233.
Hemant Pardeshi Godwin Raj Sudhansu Kumar Pati N. Mohankumar Chandan Kumar Sarkar 《Semiconductors》2012,46(10):1299-1303
Comparative assessment of III?CV heterostructure and silicon underlap DG-MOSFETs, is done using 2D Sentaurus TCAD simulation. III?CV heterostructure device has narrow-band In0.53Ga0.47As and wide-band InP layers for body, and high-K gate dielectric. Density gradient model is used for simulation and interface traps are considered. Benchmarking of simulation results show that III?CV device provides higher on current, lesser delay, lower energy-delay product and lower DIBL than silicon device. However III?CV device has higher SS and lower I on/I off than silicon device. The results indicate that there is a need to optimize the I on/I off, SS and DIBL values for specific circuits. 相似文献
234.
We propose here, a novel technique to synthesize high molecular weight (MW) poly (L ‐lactic acid)‐clay nanocomposite (PLACN), via solid state polymerization (SSP). We synthesize prepolymer of PLACN (pre‐PLACN) from both, L ‐lactic acid and L ‐lactide, as starting materials. Synthesis of pre‐PLACN from L ‐lactic acid is carried out via in situ melt polycondensation (MP) of L ‐lactic acid oligomer, followed by SSP, to achieve high MW PLACN (Mw ∼ 138,000 Da). In case of L ‐lactide as the starting material, we prepare L ‐lactide–clay intercalated mixture which yields moderate MW pre‐PLACN during subsequent ring opening polymerization (ROP). Interestingly, ROP is performed by using hydroxyl functionalized ternary catalyst system (L ‐lactide–Sn(II) octoate–oligo (L‐lactic acid) complex), which provides the terminal hydroxyl end‐groups, required for step‐growth SSP. Pre‐PLACN MW is now increased to Mw ∼ 127,000 Da, by the subsequent SSP process. 1H NMR analyses confirm that these end‐groups, are indeed consumed during SSP. During SSP, the PLACN also achieves up to 90% crystallinity, which may be due to the synchronization of the slow step‐growth SSP of poly(L ‐lactic acid) (PLA) with the crystallization kinetics. Optical purity of PLACNs is similar to that of neat PLA, whereas the thermal stability of PLACNs is significantly superior. As evidenced by wide‐angle X‐ray scattering/small‐angle X‐ray scattering analyses and in line with the literature, both, intercalated and exfoliated PLACN morphologies, have been synthesized, by suitable selection of clays. We also verify the correlation between the PLA semicrystalline morphology and the PLACN morphology, which is consistent with those of PLACN synthesized by other techniques. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers 相似文献
235.
Bokil HS Pesaran B Andersen RA Mitra PP 《IEEE transactions on bio-medical engineering》2006,53(8):1678-1687
We present a method for the real time prediction of punctuate events in neural activity, based on the time-frequency spectrum of the signal, applicable both to continuous processes like local field potentials (LFPs) as well as to spike trains. We test it on recordings of LFP and spiking activity acquired previously from the lateral intraparietal area (LIP) of macaque monkeys performing a memory-saccade task. In contrast to earlier work, where trials with known start times were classified, our method detects and classifies trials directly from the data. It provides a means to quantitatively compare and contrast the content of LFP signals and spike trains: we find that the detector performance based on the LFP matches the performance based on spike rates. The method should find application in the development of neural prosthetics based on the LFP signal. Our approach uses a new feature vector, which we call the 2d cepstrum. 相似文献
236.
Sanjay K.S. Patel Prasun Kumar Sanjeet Mehariya Hemant J. Purohit Jung-Kul Lee Vipin C. Kalia 《International Journal of Hydrogen Energy》2014
Defined co-cultures of hydrogen (H2) producers belonging to Citrobacter, Enterobacter, Klebsiella and Bacillus were used for enhancing the efficiency of biological H2 production. Out of 11 co-cultures consisting of 2–4 strains, two co-cultures composed of Bacillus cereus EGU43, Enterobacter cloacae HPC123, and Klebsiella sp. HPC793 resulted in H2 yield up to 3.0 mol mol−1 of glucose. Up-scaling of the reactor by 16-fold resulted in a corresponding increase in H2 production with an actual evolution of 7.44 L of H2. It constituted 58.2% of the total biogas. Continuous culture evolution of H2 by co-cultures (B. cereus EGU43 and E. cloacae HPC123) immobilized on ligno-cellulosic materials resulted in 6.4-fold improvement in H2 yield compared to free floating bacteria. This synergistic influence of B. cereus and E. cloacae can offer a better strategy for H2 production than undefined or mixed cultures. 相似文献
237.
Purohit Hemant Kaur Parneet Choudhary Shilpa 《Wireless Personal Communications》2022,123(4):3497-3509
Wireless Personal Communications - The COVID-19 lockdown has led all the citizens (mobile subscribers) of India to stay at home and rather work from home. The people have started consuming more... 相似文献
238.
Cross-Layer Protocol for WSN-Assisted IoT Smart Farming Applications Using Nature Inspired Algorithm
Wireless Personal Communications - The Internet of Things (IoT) is a subclass of the Industry 4.0 standard. The functionality of IoT depends on the Wireless Sensor Networks (WSNs) design. The... 相似文献
239.
Amit Kumar Chaurasia Hemant Goyal Prasenjit Mondal 《International Journal of Hydrogen Energy》2021,46(53):27244-27245