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Rashi Nathawat Vaibhav Kulshrestha V Ganesan Y.K. Vijay 《Applied Surface Science》2007,253(14):5985-5991
The effect of low energy electron beam irradiation on polycarbonate (PC) film has been studied here. The PC film of thickness 20 μm was exposed by 10 keV electron beam with 100 nA/cm2 current density. The irradiated film was characterized by mean of X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and residual gas analyzer (RGA). Formation of unsaturated bonds and partial graphitization of the surface layer are measured by XPS. Results of the AFM imaging shows electron implantation induce changes in surface morphology of the polymer film. The residual gas analyzer (RGA) spectrum of PC is recorded in situ during irradiation. The results show the change in cross-linking density of the polymer at the top surface. 相似文献
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The focus of this work is on arrival time and amplitude estimation from acoustic signals recorded at spatially separated hydrophones in the ocean. A particle filtering approach is developed that treats arrival times as "targets" and tracks their "location" across receivers, also modeling arrival time gradient. The method is evaluated via Monte Carlo simulations and is compared to a maximum likelihood estimator, which does not relate arrivals at neighboring receivers. The comparison demonstrates a significant advantage in using the particle filter. It is also shown that posterior probability density functions of times and amplitudes become readily available with particle filtering. 相似文献
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Structural Chemistry - The outbreak of severe acute respiratory syndrome coronavirus-2 is causing a serious disaster through coronavirus disease-19 (COVID-19) around the globe. A large segment of... 相似文献
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Niladri S. Karan Aaron M. Keller Siddharth Sampat Oleksiy Roslyak Ayesha Arefin Christina J. Hanson Joanna L. Casson Anil Desireddy Yagnaseni Ghosh Andrei Piryatinski Rashi Iyer Han Htoon Anton V. Malko Jennifer A. Hollingsworth 《Chemical science》2015,6(4):2224-false
Hybrid semiconductor–metal nanoscale constructs are of both fundamental and practical interest. Semiconductor nanocrystals are active emitters of photons when stimulated optically, while the interaction of light with nanosized metal objects results in scattering and ohmic damping due to absorption. In a combined structure, the properties of both components can be realized together. At the same time, metal–semiconductor coupling may intervene to modify absorption and/or emission processes taking place in the semiconductor, resulting in a range of effects from photoluminescence quenching to enhancement. We show here that photostable ‘giant’ quantum dots when placed at the center of an ultrathin gold shell retain their key optical property of bright and blinking-free photoluminescence, while the metal shell imparts efficient photothermal transduction. The latter is despite the highly compact total particle size (40–60 nm “inorganic” diameter and <100 nm hydrodynamic diameter) and the very thin nature of the optically transparent Au shell. Importantly, the sensitivity of the quantum dot emission to local temperature provides a novel internal thermometer for recording temperature during infrared irradiation-induced photothermal heating. 相似文献
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Dharminder Sharma C. B. Reddy Arun K. Shil Rashi Prakash Saroach Pralay Das 《Molecular diversity》2013,17(4):651-659
New chemical approaches were adopted for the synthesis of biologically important coumarins utilizing cyclohexane-1,3-dione derivatives as novel scaffold which were prepared from acetone and ethyl acrylate following our previous report. The stepwise strategies of aromatization, dehydrogenation, and demethylative cyclization were followed for coumarins synthesis from cyclohexane-1,3-dione derivatives. This work reports the first time cyclohexyl iodide was used for the demethylative cyclization reaction of $\upbeta , \upbeta $ -diaryl acrylates for 4-arylcoumarins synthesis. Graphical abstract 相似文献
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Furkan Ahmad Rashi Tewari Preeti Gupta Pratikshita Mishra Rakesh Shukla 《Natural product research》2016,30(4):489-492
Saraca asoca (Roxb.) de Wilde, a common tree of India, is popularly used in the Ayurvedic and modern herbal systems of medicine for genito-urinary problems of women. Considering the reported antimicrobial or anti-inflammatory effect of S. asoca bark against such infections, we studied the anti-inflammatory activity-guided isolation of active compounds from methanol extract. The methanol extract of bark has yielded 10 compounds out of which 3′-deoxyepicatechin-3-O-β-d-glucopyranoside (6) and 3′-deoxycatechin-3-O-α-l-rhamnopyranoside (8) have been found to be in vitro and in vivo active. 3′,5-Dimethoxy epicatechin (3), 3′-deoxyepicatechin-3-O-β-d-glucopyranoside (6), 3′-deoxycatechin-3-O-α-l-rhamnopyranoside (8) and epigallocatechin (9) are being reported for the first time from S. asoca. 相似文献
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Stepwise oxidation of 1,8-bis(diphenylphosphino)naphthalene and a series of (oligo)methylene-linked diphosphines with XeF2 followed by fluoride abstraction yields a family of compounds featuring phosphine, phosphonium and phosphorane moieties in close proximity. The bisphosphonium ions [(C10H6)(Ph2PF)2]2+ (5) and [CH2(Ph2PF)2]2+ (9a) exhibit remarkable Lewis acidity arising from the proximity of the phosphonium centers. The effectiveness of bisphosphonium dications (5, 9a–e) is examined in a series of Lewis acid catalysed transformations. 相似文献
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The invention of the latest tools and technology toward computer aided graphics and drawing completely change the thinking
view of researchers in analyzing and studying the behavior of a dynamical system. Inspired by work already performed and by
adopting the experimental mathematical methods of combining the theory of analytic function with computer aided drawing technology,
we generated generalized superior Mandelbrot sets (SM-sets). Also, we analyzed the effect of dynamic noise on SM-sets. 相似文献
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Kulshrestha V Acharya NK Awasthi K Nathawat R Singh M Vijay YK 《Micron (Oxford, England : 1993)》2007,38(3):326-329
Polycarbonate films (thickness 18, 25 and 38 microm) were irradiated by a beam of 100MeV Ni7+ ion. The permeability for hydrogen and carbon dioxide was measured from both sides of membrane at increasing etching time. These membranes show larger permeability from the irradiation side, than the reverse side indicating the formation of conical tracks and asymmetrical membrane. The stopping range (Se) of 100MeV Ni7+ ion beam in polycarbonate is 22microm, for 18microm thick membrane the etching time at which the permeability increases rapidly is less than that of 38microm thick membrane, for both the gases. The difference in permeability from the two sides is attributed to the conical shape of the track generated by the ions. The controlled flow rate of the membrane leads to the design of a special type of gas filter. 相似文献
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