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1.
The collision-generated hybridization which has been found responsible for the on-site mixing of the atomic-likef-state and the band-liked states in mixed valence solids has been studied for the cerium solid. A practical expression which depends on the lattice
constant and temperature has been obtained for the collision-generated hybridization. Numerical calculations show that the
valence varies continuously with lattice constant and that temperature makes the transition smoother. The collision-generated
hybridization is found to be of significant strength in the intermediate valence regime; but over a wide range of the valence
near 3.5 it varies rather slowly without preferring a particular valence. Factors which can assist the collision-generated
hybridization in stabilizing the mixed valence phase at a particular lattice constant are discussed. 相似文献
2.
The structures of loxylostosidine A and B, two new sulfoxide - containing monoterpene alkaloid glucosides, are described. 相似文献
3.
Ratan Kotipalli Bart Vermang Viktor Fjällström Marika Edoff Romain Delamare Denis Flandre 《固体物理学:研究快报》2015,9(3):157-160
The benefits of gallium (Ga) grading on Cu(In,Ga)Se2 (CIGS) solar cell performance are demonstrated by comparing with ungraded CIGS cells. Using drive‐level capacitance profiling (DLCP) and admittance spectroscopy (AS) analyses, we show the influence of Ga grading on the spatial variation of deep defects, free‐carrier densities in the CIGS absorber, and their impact on the cell's open‐circuit voltage Voc. The parameter most constraining the cell's Voc is found to be the deep‐defect density close to the space charge region (SCR). In ungraded devices, high deep‐defect concentrations (4.2 × 1016cm–3) were observed near the SCR, offering a source for Shockley–Read–Hall recombination, reducing the cell's Voc. In graded devices, the deep‐defect densities near the SCR decreased by one order of magnitude (2.5 × 1015 cm–3) for back surface graded devices, and almost two orders of magnitude (8.6 × 1014 cm–3) for double surface graded devices, enhancing the cell's Voc. In compositionally graded devices, the free‐carrier density in the absorber's bulk decreased in tandem with the ratio of gallium to gallium plus indium ratio GGI = Ga/(Ga + In), increasing the activation energy, hindering the ionization of the defect states at room temperature and enhancing their role as recombination centers within the energy band. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
4.
5.
A two dimensional simulation study was performed to investigate the photoacoustic signal properties of non-aggregated and aggregated erythrocytes. Spatial distributions of non-aggregated blood samples were generated by employing a Monte Carlo method and aggregated blood samples were simulated using a hexagonal packing scheme. For the non-aggregating case photoacoustic signals demonstrated a monotonic rise with hematocrit. For the aggregating case it was found that spectral (<20 MHz) intensity increased (11 dB at 15.6 MHz) when the aggregate size increased. This study strongly suggests that the assessment of erythrocyte aggregation level in human blood might be possible by using a photoacoustic spectroscopic method. 相似文献
6.
We have described here the physical basis for lasing without population inversion (LWOPI). This type of amplification is obtained
basically by two mechanisms: (i) one is based on atomic interference and (ii) the other is based on Fano-type interference.
We have shown here, in H2 molecules, amplification without population inversion is feasible by considering both the mechanisms. 相似文献
7.
Mujtaba SF Dwivedi A Mudiam MK Ali D Yadav N Ray RS 《Photochemistry and photobiology》2011,87(5):1067-1076
The aim of this study was to analyze the photostability and phototoxicity mechanism of anthracene (ANT) in a human skin epidermal cell line (HaCaT) at ambient environmental intensities of sunlight/UV‐R (UV‐A and UV‐B). Photomodification of ANT under sunlight/UV‐R exposure produced two photoproducts, anthrone and 9,10 anthracenedione. Generation of 1O2, O2?? and ?OH was measured under UV‐R/sunlight exposure. Involvement of reactive oxygen species (ROS) was further substantiated by their quenching with free radical quenchers. Photodegradation of 2‐deoxyguanosine and linoleic acid peroxidation showed that ROS were mainly responsible for ANT phototoxicity. ANT generates significant amount of intracellular ROS in cell line. Maximum cell viability (85%) was reduced under sunlight exposure (30 min). Results of MTT assay accord NRU assay. ANT (0.01 μg mL?1) induced cell‐cycle arrest at G1 phase. RT‐PCR demonstrated constitutive inducible mRNA expression of CYP 1A1 and 1B1 genes. Photosensitive ANT upregulates CYP 1A1 (2.2‐folds) and 1B1 (4.1‐folds) genes. Thus, the study suggests that ROS and DNA damage were mainly responsible for ANT phototoxicity. ANT exposure may be deleterious to human health at ambient environmental intensities reaching the earth’s surface through sunlight. 相似文献
8.
In silico analysis of keratinase Ker P from Pseudomonas aeruginosa revealed that its full gene of 1,497 bp constituted of a 72-bp signal sequence along with a long 520 bp pro-sequence and 905 bp core region. Position specific multiple sequence alignment of Ker P protein with other distant proteases revealed high variability within their N-terminal regions while the core protein was considerably conserved. Ker P (F1) and its four N-terminal truncations (F2-F5) lacking 72, 177, 405, 507 bp, respectively, were cloned and constitutively expressed as extracellular protein in pEZZ-18 secretory vector with Escherichia coli HB101 as the expression host. Ker P F1, Ker P F2, Ker P F3 and Ker P F4 products were active whereas no keratinolytic activity was obtained in Ker P F5. Further analysis revealed that only 187 bp pro-sequence region is required for correct folding of the protein into its active conformation and, thus, has chaperone-like activity. Further, comparative biochemical characterization revealed that the full-length keratinase Ker P F1 was catalytically more efficient than the truncated forms. Among the truncated enzymes, keratinase Ker P F4 exhibited better thermostability than Ker P F2 with a t(1/2) of >1 h at 60 °C. It also had a higher V (max) and K (m) on casein as compared with Ker P F2. However, no significant variation was observed with respect to kinetics on synthetic substrates. 相似文献
9.
A parallel algorithm for depth-first searching of a directed acyclic graph (DAG) on a shared memory model of a SIMD computer is proposed. The algorithm uses two parallel tree traversal algorithms, one for the preorder traversal and the other for therpostorder traversal of an ordered tree. Each of these traversal algorithms has a time complexity ofO(logn) whenO(n) processors are used,n being the number of vertices in the tree. The parallel depth-first search algorithm for a directed acyclic graphG withn vertices has a time complexity ofO((logn)2) whenO(n
2.81/logn) processors are used. 相似文献
10.
The emission of radiation from relativistic positrons moving in the 〈110〉 axial channels of an f.c.c. (diamond) crystal has
been studied. An expression for the radiation intensity has been obtained for the general case of positron motion. This expression
has been simplified for the particular case of well-collimated incident beam. Enhancement of the radiation over (ordinary)
bremsstrahlung has been discussed. 相似文献