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491.
Mechanistic Insight into the Nitric Oxide Dioxygenation Reaction of Nonheme Iron(III)–Superoxo and Manganese(IV)–Peroxo Complexes 下载免费PDF全文
Dr. Seungwoo Hong Dr. Pankaj Kumar Dr. Kyung‐Bin Cho Dr. Yong‐Min Lee Prof. Dr. Kenneth D. Karlin Prof. Dr. Wonwoo Nam 《Angewandte Chemie (International ed. in English)》2016,55(40):12403-12407
Reactions of nonheme FeIII–superoxo and MnIV–peroxo complexes bearing a common tetraamido macrocyclic ligand (TAML), namely [(TAML)FeIII(O2)]2? and [(TAML)MnIV(O2)]2?, with nitric oxide (NO) afford the FeIII–NO3 complex [(TAML)FeIII(NO3)]2? and the MnV–oxo complex [(TAML)MnV(O)]? plus NO2?, respectively. Mechanistic studies, including density functional theory (DFT) calculations, reveal that MIII–peroxynitrite (M=Fe and Mn) species, generated in the reactions of [(TAML)FeIII(O2)]2? and [(TAML)MnIV(O2)]2? with NO, are converted into MIV(O) and .NO2 species through O?O bond homolysis of the peroxynitrite ligand. Then, a rebound of FeIV(O) with .NO2 affords [(TAML)FeIII(NO3)]2?, whereas electron transfer from MnIV(O) to .NO2 yields [(TAML)MnV(O)]? plus NO2?. 相似文献
492.
Pankaj Kumar Vandna Sharma Chinky Jaggi Praveen Malik Kuldeep Kumar Raina 《Liquid crystals》2017,44(5):843-853
Polymer dispersed liquid crystals (PDLCs) using nematic liquid crystal and photo-curable polymer (NOA 65) were prepared by polymerisation-induced phase separation technique, in equal ratio (1:1) of polymer and liquid crystal (LC). We demonstrate that doping of small amount (0.125%, wt./wt.) of multiwall carbon nanotubes (CNTs) and orange azo dichroic dye in PDLC generously controlled the molecular orientation, dynamics of LC in droplet and size of droplets. The effects of multiwall CNTs and dye on PDLCs were studied in terms of transition temperature, droplet morphology, transmittance characteristic, contrast ratio and response time. The results exhibited that the values of the threshold electric fields were reduced from 8 V/µm (pure PDLC) to 1.18 and 1.72 V/µm, doped with multiwall CNTs and dye, respectively. The CNTs-doped PDLC shows faster switching response as compared with pure PDLC and dye-doped PDLC. However, dye-doped PDLC shows much higher contrast among all PDLC samples. Further, the results also illustrate that the birefringence value of LC in PDLCs was changed with doping of CNTs and dye. 相似文献
493.
Xing Yang Pankaj Kumar Majhi Huifang Chai Bin Liu Jun Sun Ting Liu Yonggui Liu Liejin Zhou Jun Xu Jiawei Liu Dongdong Wang Yanli Zhao Zhichao Jin Yonggui Robin Chi 《Angewandte Chemie (International ed. in English)》2021,60(1):159-165
The dominated approaches for asymmetric aldol reactions have primarily focused on the aldol carbon–carbon bond‐forming events. Here we postulate and develop a new catalytic strategy that seeks to modulate the reaction thermodynamics and control the product enantioselectivities via post‐aldol processes. Specifically, an NHC catalyst is used to activate a masked enolate substrate (vinyl carbonate) to promote the aldol reaction in a non‐enantioselective manner. This reversible aldol event is subsequently followed by an enantioselective acylative kinetic resolution that is mediated by the same (chiral) NHC catalyst without introducing any additional substance. This post‐aldol process takes care of the enantioselectivity issues and drives the otherwise reversible aldol reaction toward a complete conversion. The acylated aldol products bearing quaternary/tetrasubstituted carbon stereogenic centers are formed in good yields and high optical purities. 相似文献
494.
Comprehensive studies on dielectric properties of p-methoxy benzylidene p-decyl aniline with function of temperature and frequency in planar geometry: A potential nematic liquid crystal for display devices 下载免费PDF全文
Pankaj Kumar Tripathi Kunwar Vikram Mithlesh Tiwari and Ajay Shriram 《中国物理 B》2021,30(6):64208-064208
The dielectric properties of the nematic mesophase, p-methoxy benzylidene p-decyl aniline(MBDA), measured in planar geometry with a function of frequency and temperature are investigated in detail. The complex dielectric permittivity(ε' and ε') is also studied at a bias voltage of 10 V for planar aligned sample cell of nematic mesophase. The dielectric permittivity with bias voltage attains a higher( 2 times) value than that without bias voltage at a temperature of 56℃,which is due to the fact that the linking group of nematic molecules is internally interacted with an applied bias voltage.This is supported by observing an enhanced dielectric permittivity of nematic liquid crystal(LC) in the presence of bias voltage, which can be fully explained as the increasing of the corresponding dipole moment. The dielectric relaxation behaviors of nematic LC are also demonstrated for planar aligned sample cell. The remarkable results are observed that the relaxation frequency shifts into low frequency region with the increase of the bias voltage applied to the planar aligned sample cells. The dielectric relaxation spectra are fitted by Cole–Cole nonlinear curve fitting for nematic mesophase in order to determine the dielectric strength. 相似文献
495.
Neetu Ishwar Chandra Maurya Arun Kumar Gupta Pankaj Srivastava Lal Bahadur 《Journal of Solid State Electrochemistry》2017,21(5):1229-1241
In this work, we have prepared Al-doped TiO2 nanoparticles via a hydrothermal method and used it for making photoanode in dye-sensitized solar cell (DSSC). Material characterizations were done using XRD, AFM, SEM, TEM and EDAX. XPS results reveal that Al is introduced successfully into the structure of TiO2 creating new impurity energy levels in the forbidden gap. This resulted in tuning of the conduction band of TiO2 and reduced charge recombination which led to better current conversion efficiency of DSSC. Greater dye loading and enhanced surface area was obtained for Al-doped TiO2 compared to un-doped TiO2. I-V analysis, EIS and Bode plots are employed to evaluate photovoltaic performance. The short-circuit current density (J sc) and efficiency (η) of cell employing Al-doped TiO2 photoanode were extensively enhanced compared to the cell using un-doped TiO2. The optical band gap (E g) for Al-doped and un-doped TiO2 was obtained as 2.8 and 3.2 eV, respectively. J sc and η were 13.39 mAcm?2 and 4.27%, respectively, under illumination of 100 mWcm?2 light intensity when thin films of 1% Al-doped TiO2 was employed as photoanode in DSSC using N719 as the sensitizer dye. With the use of un-doped TiO2 as photoanode under similar conditions, J sc 5.12 mAcm?2 and η 1.06% only could be obtained. The maximum IPCE% obtained with Al-doped TiO2 and un-doped TiO2 was 67 and 38% respectively at the characteristic wavelength of dye (λ max = 540 nm). The EIS analyses revealed resistive and capacitive elements that provided an insight into various interfacial processes in terms of the charge transport. It was observed that Al-doping reduced the interfacial resistance leading to better charge transport which has improved both photocurrent density and conversion efficiency. Higher electron mobility and fast diffusion resulting in greater charge collection efficiency was obtained for Al-doped TiO2 compared to the un-doped TiO2. Using the Mott–Schottky plot, the donor density was calculated for un-doped and Al-doped TiO2. The work demonstrated that the Al-doped TiO2 is potential photoanode material for low-cost and high-efficiency DSSC. 相似文献
496.
Pankaj Kumar Sharma Hanuman Prasad Sharma Chandrashekhar Mahadeo Chakole Jaya Pandey Meenakshi Kanwar Chauhan 《印度化学会志》2022,99(3):100387
Diseases affecting the anterior segment and the external surface of the eye are usually treated by drugs applied topically. The formulations designed for this purpose are developed to deliver active pharmaceutical agents to the eye optimally. These formulations are prepared by adding various agents (excipients) that help to maintain stability of the formulation, prevent microbial contamination, and allow easy administration with adequate drug bioavailability with the minimum ocular irritation and toxic effects at the administration site. The excipients do not have their own pharmacological actions, but Vitamin E TPGS (d-α-Tocopheryl polyethylene glycol 1000 succinate) seems to break this notion. Besides having drug formulation enhancement properties, it also possesses antioxidant properties, which have been found to have a beneficial effect on various ophthalmological diseases such as age-related macular degeneration, uveitis, glaucoma, and cataract. In this review, we primarily focus on the properties and applications of Vitamin E TPGS in ocular drug delivery and the benefits of Vitamin E (Vit E) in numerous sight-threatening ailments of the rear and front segment of the eye. Additionally, p-glycoprotein inhibition and the anti-cancer potential of vitamin E TPGS have also been summarized. 相似文献
497.
The chemical investigation of ethanolic extract from rhizomes of Cautleya spicata (Sm.) Baker (Zingiberaceae) has resulted in the isolation of eight compounds which were characterised as β-sitosterol (1), β-sitosterol β-D-glucoside (2), bergapten (3), zerumin A (4), (E)-labda-8(17),12-diene-15,16-dial (5), kaempferol (6), quercetin (7) and astragalin (8). All compounds were identified by spectroscopic and chemical methods. This paper describes the first phytochemical work on C. spicata. 相似文献
498.
499.
We present here the effect of degradation on electronic properties of polymer solar cells. Investigations were performed on two types of solar cells based on the bulk‐heterojunction network of poly(3‐hexylthiophene) and phenyl [6,6] C61 butyric acid methyl ester, one with slow degradation whereas other with faster degradation. Samples were prepared in identical conditions with controlled atmosphere, but for faster degradation, one of the samples was exposed to ambient air (rich in O2 and H2O molecules) before deposition of top metal electrode. The sample with slow degradation showed linear degradation in short circuit current density (Jsc), whereas the sample with faster degradation exhibited exponential degradation in Jsc. Linear degradation happens due to degradation in the active layer only whereas the exponential degradation is because of through degradation of the solar cell. The effect of degradation is investigated on different diode parameters. Because of different degradation processes in the two samples, the variations in diode parameters with time are different. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
500.
The effective potential is used to calculate the viscosity of complex polar vapours like water and ammonia. The agreement
between theory and experiment confirms the validity of the effective potential. 相似文献