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排序方式: 共有542条查询结果,搜索用时 31 毫秒
531.
B. K. Rana R. M. Tripathi J. S. Meena S. K. Sahoo R. Topno A. K. Shukla V. D. Puranik 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(2):347-352
In the environs of uranium mining, milling and processing facilities and in the uranium mineralized terrain, a little higher
ambient radon concentration and gamma radiation level may be expected in comparison with natural background. The present study
gives a brief account of atmospheric radon concentration, gamma absorbed dose rate and radiation dose received by the members
of public in the vicinity of Narwapahar uranium mine. The ambient radon concentration in the air in the study area was found
to vary from 5 to 107 Bq m−3 with geometric mean of 24 Bq m−3 and geometric standard deviation of 1.74 Bq m−3. The measured gamma absorbed dose rate in air at 1 m above the ground ranged from 87 to 220 nGy h−1 with an overall arithmetic mean of 128 ± 18.5 nGy h−1. The mean annual effective dose received by the members of public from inhalation of radon and its progeny and external gamma
exposure was estimated to be 0.32 mSv year−1, which is comparable to other reported values elsewhere. 相似文献
532.
Lectins bind to surface receptors on target cells, and activate a cascade of events, eventually leading to altered immune
status of host. The immunomodulatory potential of purified lectin from Aspergillus nidulans was evaluated in Swiss albino mice treated intraperitoneally with seven different doses of purified lectin. Lectin prevented
BSA-induced Arthus reaction and systemic anaphylaxis. The enhanced functional ability of macrophages was evident from respiratory
burst activity and nitric oxide production in splenocyte cultures. Interferon-gamma and interleukin-6 levels were significantly
up-regulated in treated groups. Maximum stimulatory effect was observed at the dose of 1.5 mg/kg body weight. Therapeutic
potential of A. nidulans lectin was assessed against trinitrobenzene sulfonic acid-induced ulcerative colitis in male Wistar rats. Rats pre-treated
with 80 mg/kg body weight of purified lectin intraperitoneally prior to colitis induction showed lesser disease severity and
recovery within 7 days, while rats post-treated with the same dose showed recovery in 11 days. The results demonstrate immunomodulatory
effects of A. nidulans lectin in Swiss albino mice, resulting in improved immune status of the animals and unfold its curative effect against ulcerative
colitis in rat model. This is the first report on immunomodulatory and therapeutic potential of a lectin from microfungi. 相似文献
533.
M. L. Singla Rajeev Sehrawat Nidhi Rana Kulvir Singh 《Journal of nanoparticle research》2011,13(5):2109-2116
Emeraldine base (EB) polymer–ZnO nanoparticles composite films has been synthesized by solution casting technique on ITO-coated
glass substrate and characterized by XRD, FTIR and TEM for their structure and morphology. Dielectric behaviour of these composite
films has been investigated in the very low frequency region to medium frequency region (1 kHz–1 MHz). The dielectric constant
of the composite with 30% nanoparticles is almost one-tenth of the pure EB. The dielectric value becomes constant in the frequency
region greater than 400 kHz. The change in dielectric behaviour of the composite is explained on the basis of multilayered
interface formed between the ZnO nanoparticles and emeraldine chains. Nanoparticles have high energy surface which is responsible
for the decrease of free volume for the orientation of polymer chains consequently decrease in dielectric constant of the
composite. TEM images shows about 10 nm ZnO particles embedded in the emeraldine matrix. From the XRD data it has been observed
that the lattice parameters of ZnO have been modified due to the alignment of polymer chains along the basal planes of the
nanoparticles. The shift of N=Q=N and N–B–N vibration bands to higher wave number in IR indicates that interaction between
emeraldine chain and nanoparticles which provides stability to emeraldine matrix. 相似文献
534.
A. Di Nitto E. Vardaci A. Brondi G. La Rana R. Moro P. N. Nadtochy M. Trotta A. Ordine A. Boiano M. Cinausero E. Fioretto G. Prete V. Rizzi D. V. Shetty M. Barbui D. Fabris M. Lunardon G. Montagnoli S. Moretto G. Viesti N. Gelli F. Lucarelli G. N. Knyazheva E. M. Kozulin 《The European Physical Journal A - Hadrons and Nuclei》2011,47(6):1-14
Light charged particle (LCP) emission in the evaporation residue (ER) and fusion fission (FF) channels have been studied for the 200 MeV 32S + 100Mo reaction, leading to 132Ce composite nuclei at E x =122 MeV. The main goal was to study the decay of 132 Ce on the basis of an extended set of observables, to get insights on the fission dynamics. The proton and alpha particle energy spectra, their multiplicities, ER-LCP angular correlations, ER and FF angular distributions, and ER and FF cross-sections were measured. The measured observables were compared with the Statistical Model (SM). Using standard parameters, the model was able to reproduce only the pre-scission multiplicities and the FF and ER cross-sections. The calculation was observed to strongly overestimate the proton and alpha particle multiplicities in the ER channel. Disagreements were also observed for the ER-LCP correlations, the LCP energy spectra and the ER angular distribution. By varying the SM input parameters over a wide range of values, it is shown that it is not possible to reproduce all the observables simultaneously with a unique set of parameters. The inadequacy of the model in reproducing the ER particle multiplicities is also observed analysing data from the literature for other systems in the A ≈ 150 and E x ≈ 100?200 MeV region. These results indicate serious limitations about the use of the SM in extracting information on fission dynamics. 相似文献
535.
Planar Channelling Criticalities of MeV Protons in Si Crystal: Simulations, Evaluation and Applications 下载免费PDF全文
Mukhtar Ahmed Rana 《中国物理快报》2008,25(10):3724-3727
We reports a phase-space structure of MeV proton beam planar channelled along {110} planes in Si crystal using simulation results with the help of a computer code FLUX. The aim is to understand channelling conditions suitable for disorder measurement in crystals. Phase-space distribution of a planar channelled proton beam evolutes in a systematic fashion when it travels into the crystal. Planar channelled beam oscillates between phase-like and space-like conditions in which a part of the beam becomes under phase and space criticalities. These criticality conditions in planar channelling are analysed, explained and discussed with the perspective of defect measurement in crystals. 相似文献
536.
This article investigates the effects of variable thermal conductivity and variable mass diffusion coefficient on the transport of heat and mass in the flow of Casson fluid. Numerical simulations for two-dimensional flow induced by stretching surface are performed by using Galerkin finite element method (GFEM) with linear shape functions. After assembly process, nonlinear algebraic equations are linearized through Picard method and resulting linear system is solved iteratively using Gauss Seidal method with simulation tolerance 10-8. Maximum value of independent variable η is searched through numerical experiments. Grid independent study was carried out and error analysis is performed. Simulated results are validated by comparing with already published results. Parametric study is carried out to explore the physics of the flow. The concentration increases when mass diffusion coefficient is increased. The concentration and thermal boundary layer thicknesses increase when ε1 and ε are increased. The effect of generative chemical reaction on concentration is opposite to the effect of destructive chemical reaction on the concentration. 相似文献
537.
Monotonic deformation behavior of ferrite-martensite dual phase steels with martensite volume of 13-43% have been analyzed in the current investigation using micromechanics based finite element simulation on representative volume elements. The effects of martensite volume fraction on the strain partitioning behavior between soft ferrite matrix and hard martensite islands in dual phase steels during tensile deformation have been investigated. As a consequence of strain incompatibility between hard martensite and soft ferrite phases, inhomogeneous deformation and finally deformation localization occur during tensile deformation. Restricted local deformation in ferrite phase caused by the adjacent martensite islands triggers the local stress triaxiality development. As the martensite volume fraction increases, the local deformation restrictions in ferrite phase also increases and which results in higher stress triaxiality development. Similarly the strain partitioning behavior between ferrite matrix and martensite island is also influenced by the volume fraction of martensite. The strain partitioning coefficient increases with increasing martensite volume fraction. 相似文献
538.
Dr. Yang Yu Le Wang Dr. Dongqing Lin Dr. Shammi Rana Dr. Kunal S. Mali Prof. Haifeng Ling Prof. Linghai Xie Prof. Steven De Feyter Dr. Junzhi Liu 《Angewandte Chemie (International ed. in English)》2023,62(22):e202303335
Two wide-band gap U-shaped polycyclic aromatic hydrocarbons with/without boron and nitrogen (BN-) doping ( BN-1 and C-1 ) were synthesized to tune the electronic features to suit the performance requirements for organic field-effect transistor memory (OFET-NVM). The chemical structures were characterized by scanning tunneling microscopy and single-crystal diffraction. Owing to the electron-donor effect of N and the high electron affinity of B, the BN-1 -based OFET-NVM displays large ambipolar memory windows and an enhanced charge storage density compared to C-1 and most reported small molecules. A novel supramolecular system formed from BN-1 and PMMA contributes to fabricating uniform films with homogeneous microstructures, which serve as a two-in-one tunnelling dielectric and charge-trapping layer to realize long-term charge retention and reliable endurance. Our results demonstrate that both BN doping and supramolecular engineering are crucial for the charge trapping of OFET-NVM. 相似文献
539.
Bhawna Kaushik Pooja Rana Deepti Rawat Kanika Solanki Pooja Rana Shallu Sachdeva Dhanaji R. Naikwadi Ankush V. Biradar Rakesh K. Sharma 《应用有机金属化学》2023,37(1):e6936
Construction of an effective heterojunction for unimpeded flow of photogenerated charges and their prolonged separation is imperative for environmental photocatalysis. Herein, we have designed an efficient magnetic ZnO/BiVO4 type-II heterostructure, which was employed for proficient degradation of persistent methyl violet dye with an efficiency of 97.6% in 90 min and a hazardous organic pollutant, namely, bisphenol A. UV-DRS and photoluminescence studies demonstrated that the fabricated nanocomposite exhibited effective light absorption and prolonged charge separation, thereby resulting in high photocatalytic efficacy under visible light irradiation. The efficacy of developed magnetic ZnO/BiVO4 was also compared with pristine BiVO4 and undoped magnetic ZnO, which indicated that the constructed heterostructure displayed approximately threefold and sixfold activity in contrast with bare BiVO4 and undoped magnetic ZnO nanoparticles, respectively. Radical trapping studies, ESR analysis along with GC-MS analysis were conducted to elucidate the mechanistic pathway during the photodegradation process. This work provides a rational technical approach and research ideas for photocatalytic degradation of harmful organic pollutants in an environment-friendly manner by employing energy-efficient LEDs. Besides, good recyclability of catalyst makes it a promising candidate for large-scale applications. 相似文献
540.
Dibya Prakash Biswal Dipankar Singha Dr. Jagannath Panda Dr. Malay Kumar Rana 《Chemphyschem》2023,24(21):e202300311
UiO-66-NH2-IM, a fluorescent metal-organic framework (MOF), was synthesized by post-synthetic modification of UiO-66-NH2 with 2-imidazole carboxaldehyde via a Schiff base reaction. It was examined using various characterization techniques (PXRD, FTIR, NMR, SEM, TGA, UV-Vis DRS, and photoluminescence spectroscopy). The emissive feature of UiO-66-NH2-IM was utilized to detect volatile organic compounds (VOCs), metal ions, and anions, such as acetone, Fe3+, and carbonate (CO32−). Acetone turns off the high luminescence of UiO-66-NH2-IM in DMSO, with the limit of detection (LOD) being 3.6 ppm. Similarly, Fe3+ in an aqueous medium is detected at LOD=0.67 μM (0.04 ppm) via quenching. On the contrary, CO32− in an aqueous medium significantly enhances the luminescence of UiO-66-NH2-IM, which is detected with extremely high sensitivity (LOD=1.16 μM, i. e., 0.07 ppm). Large Stern-Volmer constant, Ksv, and low LOD values indicate excellent sensitivity of the post-synthetic MOF. Experimental data supported by density functional theory (DFT) calculations discern photo-induced electron transfer (PET), resonance energy transfer (RET), inner filter effect (IFE), or proton abstraction as putative sensing mechanisms. NMR and computational studies propose a proton abstraction mechanism for luminescence enhancement with CO32−. Moreover, the optical behavior of the post-synthetic material toward analytes is recyclable. 相似文献