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621.
We have analyzed the steady-state electron transfer rate through a bridge of dendrimeric architecture. The difference between the linear chain and the dendrimeric architecture has also been demonstrated with steady-state rate as a main observable in the coherent and incoherent regimes of interactions. It is shown that generally the rate of electron transfer in dendrimeric architecture is faster than the rate associated with their linear chain counterpart with similar kind of bonding connectivities. The rate depends upon the size of the molecule, core branching, and the nature of the coupling among the different nodes on the dendrimer molecule. Depending upon the nature of the donor and acceptor, phenomenological dephasing coefficient due to environment and the geometry of the dendrimeric architecture, the modification of electron transfer rate has been studied. In the regime of fully coherent interactions where all quantum effects are considered the rate shows a multiple inversion due to the dendrimer architecture which is neither available in the regime of incoherent interaction nor in the linear chain case in similar condition. We have discussed about the applicability of our model in metal-molecule-metal junction, photoinduced electron transfer process, and molecular conductor. 相似文献
622.
B. K. Rana A. K. Shukla R. Topno R. M. Tripathi V. D. Puranik 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(3):505-510
The study summarizes radiological characteristics of Banduhurang open cast mine which includes qualitative and quantitative behavior of 222Rn concentration, external gamma radiation level over the mine pit as well as in its adjoining environment, long-lived alpha (LLα) activity concentration associated with the respirable size of ore dust and assessment of dose to the mine workers in 2006–2008. The investigations reveal that geometric means (χg) of measured radon concentration were 36.39, 38.69, 26.64 and 24 Bq m?3 with respective geometric standard deviations (σg) were 1.52, 1.55, 1.36 and 1.68 Bq m?3 and χg of gamma absorbed dose rates were 0.54, 0.64, 0. 45 and 0.15 μGy h?1 with respective σg were 1.63, 1.53, 1.52 and 1.72 μGy h?1 over the mine pit, ore yard, waste yard and in the surrounding environment within a 10 km radius to the mine, respectively. The χg of LLα activity was observed to be 16 mBq m?3 with σg of 1.9 mBq m?3. The annual mean effective dose equivalent received by the member radiation workers of Banduhurang mine was estimated to 1.41 mSv y?1, which is about 7% of the prescribed dose limits of 20 mSv y?1. 相似文献
623.
The purpose of this paper is to introduce a new system of generalized resolvent equations with corresponding system of variational
inclusions in uniformly smooth Banach spaces. We establish an equivalence relation between system of generalized resolvent
equations and system of variational inclusions. The iterative algorithms for finding the approximate solutions of system of
generalized resolvent equations are proposed. The convergence of approximate solutions of system of generalized resolvent
equations obtained by the proposed iterative algorithm is also studied.
相似文献
624.
Rakhi Grover Ritu Srivastava Omwati Rana A.K. Srivastava K.K. Maurya K.N. Sood D.S. Mehta M.N. Kamalasanan 《Journal of luminescence》2012,132(2):330-336
Hybrid organic–inorganic light emitting devices combine the color purity and durability of inorganic light emitting diodes (LEDs) with high efficiency, flexibility and low processing cost of organic LEDs (OLEDs). A significant challenge is to incorporate inorganic nanocrystals inside the OLED structure. In the present work, thin films of CdS were successfully incorporated inside standard OLED structure using vacuum thermal evaporation technique. For the characterization of these films, they were deposited on plain glass plates at room temperature and studied using structural (XRD and TEM), morphological (SEM and AFM) and optical (UV and PL) techniques. The films were found to be composed of nanocrystals of CdS in which the size of the crystals increased with the increase in film thickness. The hybrid organic–inorganic LEDs showed improved luminance and efficiency as compared to the organic LED without CdS layers. 相似文献
625.
626.
Devendra Kumar Rana Vanya SrivastavR. Pal B.S. Yadav 《Infrared Physics & Technology》2012,55(1):11-14
Transfer length method (TLM) structures were fabricated to characterize the Ni/Au/AuGe-n+-GaAs contacts for quantum dot infrared photodetector (QDIP). Low specific contact resistance of the order of 10−5 Ω cm2 indicates formation of a good Ohmic contact. The current-voltage measurements show that current transport is linear with no significant interfacial modification due to alloying of the contact metal. Low contact resistance makes this scheme suitable for the fabrication of heterostructure QDIP devices. 相似文献
627.
Mukhtar Ahmad R. Grössinger M. Kriegisch F. Kubel M.U. Rana 《Current Applied Physics》2012,12(6):1413-1420
A series of Al-substituted Co2W hexaferrites BaCo2AlxFe16 ? xO27 (x = 0, 0.2, 0.4, 0.6, 0.8, 1) synthesized by sol-gel autocombustion method have been investigated. The samples were characterized by DTA/TGA analysis, FTIR spectroscopy, X-ray Diffractometer and field emission gun scanning electron microscopy (FEGSEM). Magnetic behavior of a selected sample was examined up to a magnetic field of 9T between a temperature range of 4.2 K–400 K. The values of saturation magnetization were calculated by the law of approach to saturation. The coercivity of the investigated sample has a value of about hundred oersteds at room temperature which is favorable for EM materials. The complex permittivity and complex permeability of a composite sample have been measured in the frequency range of 0.5–13 GHz. Based on the theoretical calculation of re?ection loss; the microwave absorption properties have been investigated. The results indicate that the attenuation peak frequency of these compounds can be tuned for the desired frequency by varying the thickness of the absorber. 相似文献
628.
Interactions between a polymer and a surfactant were studied via surface tension measurements. Poly(ethylene glycol) and
sodium dodecyl sulfate were used as a polymer and a surfactant, respectively. The addition of polymer affected the CMC value
of the surfactant. The interpretations of the data and theoretical plots of polymer-surfactant interactions are discussed
using a theoretical model.
Received: 28 September 2000 Accepted: 3 October 2000 相似文献
629.
Homogeneous electrochemical catalysis of N2O reduction to N2 is investigated with a series of organic catalysts and rhenium and manganese bipyridyl carbonyl complexes. An activation-driving force correlation is revealed with the organic species characteristic of a redox catalysis involving an outer-sphere electron transfer from the radical anions or dianions of the reduced catalyst to N2O. Taking into account the previously estimated reorganization energy required to form the N2O radical anions leads to an estimation of the N2O/N2O˙− standard potential in acetonitrile electrolyte. The direct reduction of N2O at a glassy carbon electrode follows the same quadratic activation driving force relationship. Our analysis reveals that the catalytic effect of the mediators is due to a smaller reorganization energy of the homogeneous electron transfer than that of the heterogeneous one. The physical effect of “spreading” electrons in the electrolyte is shown to be unfavorable for the homogeneous reduction. Importantly, we show that the reduction of N2O by low valent rhenium and manganese bipyridyl carbonyl complexes is of a chemical nature, with an initial one-electron reduction process associated with a chemical reaction more efficient than the simple outer-sphere electron transfer process. This points to an inner-sphere mechanism possibly involving partial charge transfer from the low valent metal to the binding N2O and emphasizes the differences between chemical and redox catalytic processes.Homogeneous electrochemical catalysis of N2O reduction to N2 is investigated with a series of organic catalysts and rhenium and manganese bipyridyl carbonyl complexes. 相似文献
630.
Joanna Agnieszka Komorowska-Müller Tanushka Rana Bolanle Fatimat Olabiyi Andreas Zimmer Anne-Caroline Schmle 《Molecules (Basel, Switzerland)》2021,26(19)
Physiological brain aging is characterized by gradual, substantial changes in cognitive ability, accompanied by chronic activation of the neural immune system. This form of inflammation, termed inflammaging, in the central nervous system is primarily enacted through microglia, the resident immune cells. The endocannabinoid system, and particularly the cannabinoid receptor 2 (CB2R), is a major regulator of the activity of microglia and is upregulated under inflammatory conditions. Here, we elucidated the role of the CB2R in physiological brain aging. We used CB2R−/− mice of progressive ages in a behavioral test battery to assess social and spatial learning and memory. This was followed by detailed immunohistochemical analysis of microglial activity and morphology, and of the expression of pro-inflammatory cytokines in the hippocampus. CB2R deletion decreased social memory in young mice, but did not affect spatial memory. In fact, old CB2R−/− mice had a slightly improved social memory, whereas in WT mice we detected an age-related cognitive decline. On a cellular level, CB2R deletion increased lipofuscin accumulation in microglia, but not in neurons. CB2R−/− microglia showed an increase of activity markers Iba1 and CD68, and minor upregulation in tnfa and il6 expression and downregulation of ccl2 with age. This was accompanied by a change in morphology as CB2R−/− microglia had smaller somas and lower polarity, with increased branching, cell volume, and tree length. We present that CB2Rs are involved in cognition and age-induced microglial activity, but may also be important for microglial activation itself. 相似文献