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991.
The aim of present study is to examine the photo-initiation efficiency of N,N-dimethylacrylamide-based allylic ammonium salt as one component addition-fragmentation agent (cationic photoinitiator cum
radical source) in free radical accelerated cationic polymerization. Novel addition-fragmentation agent (AFA), 2-(N,N-dimethylcarboxy-3-propenyl)(phenylcarbonyl-4-phenylene) dimethyl ammonium hexafluoroantimonate (DMPDA) was synthesized as
cationic photoinitiator and its initiation efficiency was examined in polymerization of cyclohexene oxide (CHO), isobutyl
vinyl ether (IBVE), and n-butyl vinyl ether (n-BVE) in CH2Cl2 solvent at wavelength λ > 290 nm. The rate of polymerization increases with the increase in initiator concentration and reaction
time. The results demonstrate that DMPDA acts as an efficient photoinitiator (AFA) without use of radical source in free radical
accelerated cationic polymerization. 相似文献
992.
Zhu L Verma R Roccatano D Ni Y Sun ZH Schwaneberg U 《Chembiochem : a European journal of chemical biology》2010,11(16):2294-2301
Arginine deiminase (ADI, EC 3.5.3.6) is a potential antitumor drug for the treatment of arginine‐auxotrophic tumors such as hepatocellular carcinomas (HCCs) and melanomas, and studies on human lymphatic leukemia cell lines have confirmed that ADI has antiangiogenic activity. Recent studies showed that a combination of taxane and ADI‐PEG20, which induces caspase‐independent apoptosis, is more effective than taxane monotherapy for prostate cancer. The main limitation of ADI from Pseudomonas plecoglossicida (PpADI) and of many other ADI enzymes lies in their pH‐dependent activity profile. PpADI has a pH optimum at 6.5 and a pH shift from 6.5 to 7.5 results in an ~80 % activity drop (the pH of human plasma is 7.35 to 7.45). In 2010, we reported a proof of concept for ADI engineering by directed evolution that resulted in variant M2 (K5T/D44E/H404R). M2 has a pH optimum of pH 7.0, a fourfold higher kcat value than the wild‐type PpADI (pH 7.4, 0.5 M phosphate buffer), and an increased Km value for substrate arginine. In our latest work, variants M5 (K5T/D38H/D44E/A128T/H404R) and M6 (K5T/D38H/D44E/A128T/E296K/H404R) were generated by directed evolution by employing PBS buffer (pH 7.4), which mimics physiological conditions. The S0.5 value of parent M3 (K5T/D44E/A128T/H404R) decreased from 2.01 to 1.48 mM (M5) and 0.81 mM (M6). The S0.5 value of M6 (0.81 mM ) is lower than that of wild‐type PpADI (1.30 mM ); the kcat values improved from 0.18 s?1 (wild‐type PpADI) to 17.56 s?1 (M5, 97.6‐fold) and 11.64 s?1 (M6, 64.7‐fold). 相似文献
993.
Gowda KV Rajan DS Mandal U Selvan PS Sam Solomon WD Bose A Sarkar AK Pal TK Chattaraj TK 《Drug development and industrial pharmacy》2006,32(10):1219-1225
The bioequivalence of two oral formulations containing aceclofenac 100 mg was determined in 24 healthy Indian male volunteers. The study was designed as a single dose, fasting, two-period two-sequence crossover study with a washout period of 1 week. The content of aceclofenac in plasma was determined by a validated HPLC method with UV detection. The preparations were compared using the parameters area under the plasma concentration-time curve (AUC0-t), area under the plasma concentration-time curve from zero to infinity (AUC0-∞), peak plasma concentration (Cmax), and time to reach peak plasma concentration (tmax). No statistically significant difference was observed between the logarithmic transformed AUC0-∞ and Cmax values of the two preparations. The 90% confidence interval for the ratio of the logarithmic transformed AUC0-t, AUC0-∞, and Cmax were within the bioequivalence limit of 0.80-1.25. 相似文献
994.
Ved Parkash Sharma Harminder Pal Singh Ravinder Kumar Kohli 《The Science of the total environment》2009,407(21):5543-5547
During the last couple of decades, there has been a tremendous increase in the use of cell phones. It has significantly added to the rapidly increasing EMF smog, an unprecedented type of pollution consisting of radiation in the environment, thereby prompting the scientists to study the effects on humans. However, not many studies have been conducted to explore the effects of cell phone EMFr on growth and biochemical changes in plants. We investigated whether EMFr from cell phones inhibit growth of Vigna radiata (mung bean) through induction of conventional stress responses. Effects of cell phone EMFr (power density: 8.55 µW cm− 2; 900 MHz band width; for ½, 1, 2, and 4 h) were determined by measuring the generation of reactive oxygen species (ROS) in terms of malondialdehyde and hydrogen peroxide (H2O2) content, root oxidizability and changes in levels of antioxidant enzymes. Our results showed that cell phone EMFr significantly inhibited the germination (at ≥2 h), and radicle and plumule growths (≥1 h) in mung bean in a time-dependent manner. Further, cell phone EMFr enhanced MDA content (indicating lipid peroxidation), and increased H2O2 accumulation and root oxidizability in mung bean roots, thereby inducing oxidative stress and cellular damage. In response to EMFr, there was a significant upregulation in the activities of scavenging enzymes, such as superoxide dismutases, ascorbate peroxidases, guaiacol peroxidases, catalases and glutathione reductases, in mung bean roots. The study concluded that cell phone EMFr inhibit root growth of mung bean by inducing ROS-generated oxidative stress despite increased activities of antioxidant enzymes. 相似文献
995.
Heat transfer modelling on windows and glazing under the exposure of solar radiation 总被引:1,自引:0,他引:1
Sujoy Pal 《Energy and Buildings》2009,41(6):654-661
Due to the effect of solar radiation on windows and glazing system the evaluation of heat flow is of primary importance in modeling the thermal performance within building interiors to account thermal comfort and overall energy consumption of a building. In this context the optical properties of window glazing are measured to determine the percentage absorption of incident solar radiation. An experimental study was performed in a room to measure the glazing surface temperature due to the global radiation on it. The corresponding window plane global radiation and horizontal global radiation were measured outside for simulation. Mathematical models have been developed to simulate the window plane solar radiation and corresponding glazing surface temperature aiming at validating the measured values. The thermal model is concerned with laminar heat transfer for natural and forced convection process according to the ambient conditions. The estimated errors between experimental and simulated values of window plane radiation and glazing temperature are shown to be within ±5%. Using the developed thermal model the heat flow inside the room through windows is determined. Thus overall heat transfer coefficient of glazing (U-factor) and the Solar Heat Gain (SHG) of building interior have been predicted from the simulation. 相似文献
996.
Bonamali Pal Isha Singh Kunal Angrish Raghavendra Aminedi Niranjan Das 《Materials Chemistry and Physics》2012
Superior antimicrobial activity of 2 wt.% Pt-dispersed TiO2 thin film was observed in photokilling Gram-negative Escherichia coli bacteria within 5 min irradiation (640 μW cm−2, λ > 340 nm) from UV torch than bare TiO2 film. Severe disruption of cell membrane has occurred over illuminated Pt-TiO2 catalysts films coated with 100–300 μg powders per 5 cm2 areas over sterilized glass slides. The Pt dispersion onto TiO2 by impregnation–hydrogen reduction always exhibited better photokilling effect than Pt photodeposition, irrespective of Pt–TiO2 dose and light exposure time. Similar trend in photoactivity difference between two Pt–TiO2 catalysts is also observed in aqueous slurry because of the unlike surface structure of TiO2 due to different annealing temperatures, size and nature of Pt particles dispersion onto TiO2 photocatalysts. 相似文献
997.
Erbium doped glasses having composition 20ZnO·xBi2O3·(79.5 − x)B2O3 (15 ≤ x ≤ 35, x in mol%) were prepared by melt-quench technique. The spectroscopic properties were investigated using optical absorption and fluorescence spectra. The Judd–Ofelt intensity parameters, Ωλ (λ = 2, 4, 6) were determined from the spectral intensities of absorption bands in order to calculate the radiative transition probability (AR), radiative life time (τR), branching ratio (βR) for various excited luminescent states. Using the emission spectra, full width at half maximum (FWHM), stimulated emission cross-section (σe) and figure of merit (FOM) were evaluated. The high values of Judd–Ofelt parameters indicate a substantial mixing of other electronic configuration into the 4fN configuration by the random crystal field in the glasses. All the intensity parameters (Ωλ) decrease with increase in Bi2O3 content and the effect is found to be most pronounced for Ω2 values. The structural investigations of the glasses were carried out by recording the IR transmission spectra. A correlation between the network forming units with the multi-phonon relaxation rate and hence with the possibility of radiative quantum efficiency has been made. In addition, various physical and optical parameters have been determined from the measured density and refractive index values. 相似文献
998.
Verma M Joshi S Bisht NS Kandpal HC Senthilkumaran P Joseph J 《Journal of the Optical Society of America. A, Optics, image science, and vision》2012,29(3):195-199
It is shown that the generation of surface plasmons on a metal-dielectric interface, i.e., a Au-double-slit and air interface, appreciably affects the intensity of the diffracted light. With a specific example of Au-double-slit and electro-optic devices before the slits, the spectral switching in the diffracted field with the polychromatic light is shown for the first time, to our knowledge. It is found that at the observation point due to the surface plasmon effect the intensity of the diffracted light periodically increases and decreases with the separation of the double-slit. 相似文献
999.
In this paper we have analyzed the combined effects of magnetic field and convective diffusion of species through a non-Darcy porous medium over a vertical stretching sheet with temperature dependent viscosity and non-uniform heat source/sink. The boundary layer equations are transformed into ordinary differential equations using self-similarity transformation which are then solved numerically using fifth-order Runge–Kutta Fehlberg method with shooting technique for various values of the governing parameters. The effects of electric field parameter, non-uniform heat source/sink parameters and Schmidt number on concentration profiles are analyzed and discussed graphically. Favorable comparisons with previously published work on various special cases of the problem are obtained. 相似文献
1000.
Free-standing, bi-directionally permeable and ultra-thin anodic aluminum oxide (AAO) membranes establish attractive templates (host) for the synthesis of nano-dots and rods of various materials (guest). This is due to their chemical and structural integrity and high periodicity on length scales of 5-150 nm which are often used to host photoactive nano-materials for various device applications including dye-sensitized solar cells. In the present study, AAO membranes are synthesized by using electrochemical methods and a detailed structural characterization using FEG-SEM, XRD and TGA confirms the porosity and purity of the material. Defect-mediated photoluminescence quenching of the porous AAO membrane in the presence of an electron accepting guest organic molecule (benzoquinone) is studied by means of steady-state and picosecond/femtosecond-resolved luminescence measurements. Using time-resolved luminescence transients, we have also revealed light harvesting of complexes of porous alumina impregnated with inorganic quantum dots (Maple Red) or gold nanowires. Both the F?rster resonance energy transfer and the nano-surface energy transfer techniques are employed to examine the observed quenching behavior as a function of the characteristic donor-acceptor distances. The experimental results will find their relevance in light harvesting devices based on AAOs combined with other materials involving a decisive energy/charge transfer dynamics. 相似文献