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排序方式: 共有726条查询结果,搜索用时 15 毫秒
41.
John A. Mikroyannidis Antonis N. Kabanakis S. S. Sharma Ganesh D. Sharma 《Advanced functional materials》2011,21(4):746-755
[6,6]‐phenyl‐C‐61‐butyric acid methyl ester (PCBM) and poly(3‐hexylthiophene) (P3HT) are the most widely used acceptor and donor materials, respectively, in polymer solar cells (PSCs). However, the low LUMO (lowest unoccupied molecular orbital) energy level of PCBM limits the open circuit voltage (Voc) of the PSCs based on P3HT. Herein a simple, low‐cost and effective approach of modifying PCBM and improving its absorption is reported which can be extended to all fullerene derivatives with an ester structure. In particular, PCBM is hydrolyzed to carboxylic acid and then converted to the corresponding carbonyl chloride. The latter is condensed with 4‐nitro‐4’‐hydroxy‐α‐cyanostilbene to afford the modified fullerene F . It is more soluble than PCBM in common organic solvents due to the increase of the organic moiety. Both solutions and thin films of F show stronger absorption than PCBM in the range of 250–900 nm. The electrochemical properties and electronic energy levels of F and PCBM are measured by cyclic voltammetry. The LUMO energy level of F is 0.25 eV higher than that of PCBM. The PSCs based on P3HT with F as an acceptor shows a higher Voc of 0.86 V and a short circuit current (Jsc) of 8.5 mA cm?2, resulting in a power conversion efficiency (PCE) of 4.23%, while the PSC based on P3HT:PCBM shows a PCE of about 2.93% under the same conditions. The results indicate that the modified PCBM, i.e., F , is an excellent acceptor for PSC based on bulk heterojunction active layers. A maximum overall PCE of 5.25% is achieved with the PSC based on the P3HT: F blend deposited from a mixture of solvents (chloroform/acetone) and subsequent thermal annealing at 120 °C. 相似文献
42.
Randeep Rakwal Ganesh Kumar Agrawal Junko Shibato Tetsuji Imanaka Satoshi Fukutani Shigeru Tamogami Satoru Endo Sarata Kumar Sahoo Yoshinori Masuo Shinzo Kimura 《International journal of molecular sciences》2009,10(3):1215-1225
We report molecular changes in leaves of rice plants (Oryza sativa L. - reference crop plant and grass model) exposed to ultra low-dose ionizing radiation, first using contaminated soil from the exclusion zone around Chernobyl reactor site. Results revealed induction of stress-related marker genes (Northern blot) and secondary metabolites (LC-MS/MS) in irradiated leaf segments over appropriate control. Second, employing the same in vitro model system, we replicated results of the first experiment using in-house fabricated sources of ultra low-dose gamma (γ) rays and selected marker genes by RT-PCR. Results suggest the usefulness of the rice model in studying ultra low-dose radiation response/s. 相似文献
43.
Nanoparticles (about 200 nm thick and 600–12000 nm long flakes) of dipyridamole, a poorly water-soluble anti-thrombosis drug, are produced by supercritical antisolvent solvent with enhanced mass transfer method. Applicability of sonication in liquid CO2 for mixing of drug and excipient nanoparticles is demonstrated for several binary mixtures of drug and excipient. The drug particles are mixed with three different excipients: silica nanoparticles, lactose microparticles, and polyvinylpyrrolidone nanoparticles. To intimately mix at nanoscale, macro mixtures of dipyridamole and excipient particles are sonicated in liquid carbon dioxide. The effects of ultrasonic energy, amplitude, and component weight ratio are studied for the binary mixtures. Characterization of mixing is done using several methods. Scanning electron microscopy is used as a primary method for microscopic analysis. Two macroscopic effects, drug dissolution and blend homogeneity (relative standard deviation), are used to characterize mixing quality of drug/lactose mixture. Results of drug dissolution and blend homogeneity show effectiveness of the proposed mixing method for fine size particles. Material handling properties of drug/silica and lactose/silica mixtures were examined. Upon mixing, the handling properties are significantly improved as measured by compressibility index and Hausner ratio. Liquid CO2 offers an environmentally benign media for mixing. In addition, the mixture obtained does not contain any residual solvent as compared to the sonication in organic liquids. Upon depressurization, CO2 is easily removed from the mixture providing a facile recovery of the product. 相似文献
44.
Manjunatha Pattabi S. C. Gurumurthy Ganesh Sanjeev A. B. Gaikwad 《Journal of Materials Science: Materials in Electronics》2011,22(8):1095-1100
Results of the investigations carried out on the electrical behavior of silver particulate films deposited on electron beam
irradiated polystyrene (PS) coated substrates held at a temperature of 455 K in a vacuum of 8 × 10−6 torr at a constant deposition rate of 0.4 nm/s are reported. It is known that when metals are evaporated on to softened polymer
substrates, subsurface particulate structures are formed whose morphology is dependent on deposition parameters. Further,
it was shown that the morphology is dependent on polymer-metal interaction. The present work demonstrates that the polymer-metal
interaction can be brought about in inert polymers like PS by electron irradiation. The results indicate that the films deposited
on PS irradiated to a dose of 20 and 25 kGy gives rise to smaller clusters with smaller inter-cluster separation, better suited
for sensor applications. The induced polymer-metal interaction is attributed to the creation of free radicals due to the 8 MeV
electron irradiation. 相似文献
45.
46.
M
S Ghatnekar J
S Pai M Ganesh 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(4):444-448
Bacterial polyesters have shown potential as biodegradable plastics. Microorganisms capable of producing these polyesters from cheaper carbon sources and methods for their efficient recovery are widely studied worldwide. Methylobacterium sp V49, an environmental isolate, was cultivated on a mineral salts medium containing different carbon sources. Maximum accumulation of poly‐3‐hydroxybutyrate (PHB) within the bacterial cell was observed with glucose as the carbon source. Methanol and sugars such as sucrose and lactose also induced PHB accumulation. The effect of C:N ratio on polymer accumulation was studied. Different strategies for the extraction and recovery of the polymer from the cells were compared. A non‐solvent‐based method using a high‐pressure homogenizer in the presence of SDS was found to be the most satisfactory. Maximum recovery of 98% was achieved by homogenizing the cells at 400 kgcm?2 in 5% SDS solution. © 2002 Society of Chemical Industry 相似文献
47.
We study here a model hybrid system consisting of a flexible rectangular space structure such as a solar cell array, hoisted at one end by a movable rigid hub, set to vibration from certain initial conditions, but subject to uncertain disturbing forces distributed along its length. Assuming that the control of vibrations is sought by a damper at the hub end proportional to a general nonlinear function of the velocity of the point, we obtain an H2 energy estimate of vibrations over a time interval [0,T] in terms of initial energy of the system and the time integral of the L2 norm of the disturbance over the length of the panel. From this, estimates of tolerance level of the disturbances are obtained. Both torsional and flexural modes of vibration are considered. 相似文献
48.
V Ganesh 《Electrochimica acta》2004,49(21):3561-3572
We show in this work that template electrodeposition of nickel at room temperature from a nickel sulphamate bath prepared in a new hexagonal liquid crystalline phase of water-Triton X-100-poly (acrylic acid) results in a highly porous surface. The roughness factor value of about 3620 obtained for this coating is the highest value reported in the literature for any electrodeposited nickel. The scanning electron microscopy (SEM) and scanning tunneling microscopy (STM) pictures show the formation of porous deposit with granular features in between the pores. The single electrode double layer capacitance value measured for the deposit is 338 mF cm−2, which translates into a specific capacitance of 50 F g−1 without any post-thermal treatment of the electrode, suggesting its utility in super capacitors. Electrochemical studies using cyclic voltammetry (CV), Tafel plots and electrochemical impedance spectroscopy (EIS) and comparison of these results with some existing high surface area Ni catalysts show that the material has potential application as an excellent hydrogen evolving cathode. 相似文献
49.
R. Johnson I. Ganesh B. P. Saha G. V. Narasimha Rao Y. R. Mahajan 《Journal of Materials Science》2003,38(13):2953-2961
The extruded cordierite honeycomb structure from a stoichiometric formulation of talc, kaolinite, and alumina was subjected to TGA-DSC, dilatometric and XRD investigations. The experimental observations were made to identify the phase transformation sequence in order to understand the solid state reactions involved in the cordierite formation. A maximum cordierite content of 90% was achieved for the samples sintered at 1693 K with a soaking time of 4 h, corresponding to a lowest coefficient of thermal expansion (CTE) of 0.74 × 10–6/K (along the direction of extrusion) was observed. Attempts were made to establish correlations with cordierite content, processing temperature and CTE of the samples. A few mechanisms are proposed to explain our observations. Attempts are also made to rationalize the low CTE observed along the direction of extrusion on the basis of orientation of anisotropic cordierite crystals as revealed by the transverse I-ratio calculated from the XRD patterns. Effect of CaO doping on CTE of cordierite has been studied in the present work. It was observed that though there is an increase in bulk thermal expansion of cordierite honeycombs on CaO doping due to the absence of micro-cracks as reveled by thermal cycling hysteresis, axial anisotropy was found to be reduced significantly. 相似文献
50.
Structure‐Guided Design of Thiazolidine Derivatives as Mycobacterium tuberculosis Pantothenate Synthetase Inhibitors
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Parthiban Brindha Devi Ganesh Samala Jonnalagadda Padma Sridevi Shalini Saxena Mallika Alvala Elena G. Salina Prof. Dharmarajan Sriram Prof. Perumal Yogeeswari 《ChemMedChem》2014,9(11):2538-2547
The pantothenate biosynthetic pathway is essential for the persistent growth and virulence of Mycobacterium tuberculosis (Mtb) and one of the enzymes in the pathway, pantothenate synthetase (PS, EC: 6.3.2.1), encoded by the panC gene, has become an appropriate target for new therapeutics to treat tuberculosis. Herein, we report nanomolar thiazolidine inhibitors of Mtb PS developed by a rational inhibitor design approach. The thiazolidine compounds were discovered by using energy‐based pharmacophore modelling and subsequent in vitro screening, which resulted in compounds with a half maximal inhibitory concentration (IC50) value of (1.12±0.12) μM . These compounds were subsequently optimised by a combination of modelling and synthetic chemistry. Hit expansion of the lead by chemical synthesis led to an improved inhibitor with an IC50 value of 350 nM and an Mtb minimum inhibitory concentration (MIC) of 1.55 μM . Some of these compounds also showed good activity against dormant Mtb cells. 相似文献