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排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Golam Haider Krishna Sampathkumar Tim Verhagen Lukáš Nádvorník Farjana J. Sonia Václav Valeš Jan Sýkora Peter Kapusta Petr Němec Martin Hof Otakar Frank Yang-Fang Chen Jana Vejpravová Martin Kalbáč 《Advanced functional materials》2021,31(29):2102196
Recent advancements in isolation and stacking of layered van der Waals materials have created an unprecedented paradigm for demonstrating varieties of 2D quantum materials. Rationally designed van der Waals heterostructures composed of monolayer transition-metal dichalcogenides (TMDs) and few-layer hBN show several unique optoelectronic features driven by correlations. However, entangled superradiant excitonic species in such systems have not been observed before. In this report, it is demonstrated that strong suppression of phonon population at low temperature results in a formation of a coherent excitonic-dipoles ensemble in the heterostructure, and the collective oscillation of those dipoles stimulates a robust phase synchronized ultra-narrow band superradiant emission even at extremely low pumping intensity. Such emitters are in high demand for a multitude of applications, including fundamental research on many-body correlations and other state-of-the-art technologies. This timely demonstration paves the way for further exploration of ultralow-threshold quantum-emitting devices with unmatched design freedom and spectral tunability. 相似文献
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An ecofriendly and biodegradable porous structure was prepared from drying aqueous foams based on nano fibrillated cellulose (NFC), extracted from softwood pulp by subcritical water/CO2 treatment (SC-NFC). The primary aim of this work was to use the modified SC-NFC as stabilizer for a water-based Pickering emulsion which upon drying, yielded porous cellulosic materials, a good dye adsorbent. In order to exploit the carboxymethylated SC-NFC (CMSC-NFC, with a degree of substitution of 0.35 and a charge density of 649 μeqv/g) as a stabilizer for water-based Pickering emulsion in subsequent step, an optimized quantity of octyl amine (30 mg/g of SC-NFC) was added to make them partially hydrophobic. A series of dry foam structures were prepared by varying the concentrations of treated CMSC-NFCs and 4 wt% was found to be the optimum concentration to yield foam with high porosity (99%) and low density (0.038 g/cc) along with high compression strength (0.24 MPa), superior to the conventionally extracted NFC. The foams were applied to capture as high as 98% of methylene blue dyes, making them a potential green candidate for treating industrial effluent. In addition, the dye adsorption kinetics and isotherms were found to be well suited with second order kinetics and Langmuir isotherm models. 相似文献
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Darothi Bairagi Venkataramana Munukuti Pallabi Bhuyan Rajib Saha Sumantra Mandal 《工业材料与腐蚀》2021,72(5):829-838
The influence of cementite spheroidization on the impact toughness and electrochemical properties of a high-carbon steel has been thoroughly investigated in this study. Heavy warm rolling, followed by 2 h of annealing, has resulted in near-complete spheroidization, leading to a microstructure consisting of nano-cementite globules dispersed in the ultrafine-grained ferritic matrix. The Charpy impact test exhibited superior impact toughness with increased spheroidization. It is validated by the presence of abundant dimples in the fractographs of spheroidized specimens, in contrast to the as-received one that experienced a brittle failure due to its lamellar pearlitic structure. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) carried out in a 3.5% NaCl solution revealed that the corrosion resistance of the alloy gets improved with the increase in the degree of spheroidization. This is attributed to the lower susceptibility of the spheroidized specimen to microgalvanic corrosion owing to the minimum area of contact between nano-spheroidized cementite and ferrite, as elucidated with the help of EIS results aided by equivalent electrical circuit model. 相似文献
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Klimis?S.?NtalianisEmail author Anastasios?D.?Doulamis Nikolaos?D.?Doulamis Nikos?E.?Mastorakis Athanasios?S.?Drigas 《Journal of Signal Processing Systems》2015,80(2):153-161
In this paper, we present a novel memory access reduction scheme (MARS) for two-dimension fast cosine transform (2-D FCT). It targets programmable DSPs with high memory-access latency. It reduces the number of memory accesses by: 1) reducing the number of weighting factors and 2) combining butterflies in vector-radix 2-D FCT pruning diagram from two stages to one stage with an efficient structure. Hardware platform based on general purpose processor is used to verify the effectiveness of the proposed method for vector-radix 2-D FCT pruning implementation. Experimental results validate the benefits of the proposed method with reduced memory access, less clock cycle and fewer memory space compared with the conventional implementation. 相似文献
7.
Wojciech Jó?wicki Anna A. Bro?yna Jerzy Siekiera Andrzej T. Slominski 《International journal of molecular sciences》2015,16(2):3783-3803
RCAS1 is a protein that participates in regulation of the tumor microenvironment and its immune responses, all in order to evade the immune system. The aim of this study was to analyze RCAS1 expression in urothelial bladder cancer cells (and in fibroblasts and macrophages of the tumor stroma) and its relationship with the histological pattern of malignancy. Eighty-three postcystectomy patients were enrolled. We analyzed the histological maturity (grade), progress (pT stage), tissue invasion type (TIT), nonclassic differentiation number (NDN), and the ability to metastasize (pN). The expression of RCAS1 protein was analyzed by immunohistochemistry. Indicators of histological malignancy were observed solely in association with the RCAS1 expression in cells in the border parts (BPs) of the tumor. Histological malignancy of the tumor, indicated by the pT and pN, and metastasis-free survival time, correlated significantly with RCAS1 expression in tumor neoplastic cells, whereas malignancy determined by grade, TIT, and NDN correlated with RCAS1 expression in fibroblasts and macrophages in the tumor microenvironment. These findings suggest that the increased RCAS1 expression depends on its cellular source and that RCAS1 expression itself is a component of various signaling pathways. The immune escape occurs within the tumor BPs, where the increase in the RCAS1 expression occurs within tumor cells and stromal cells in its microenvironment. We conclude that the histological pattern of tumor malignancy, indicated by grade, TIT, NDN, pT, and pN is a morphological indicator of immune escape. 相似文献
8.
Klaus Reinhardt Hans Georg Breunig Aisada Uchugonova Karsten K?nig 《Journal of the Royal Society Interface》2015,12(110)
We explore the possibility of characterizing sperm cells without the need to stain them using spectral and fluorescence lifetime analyses after multi-photon excitation in an insect model. The autofluorescence emission spectrum of sperm of the common bedbug, Cimex lectularius, was consistent with the presence of flavins and NAD(P)H. The mean fluorescence lifetimes showed smaller variation in sperm extracted from the male (tau m, τm = 1.54–1.84 ns) than in that extracted from the female sperm storage organ (tau m, τm = 1.26–2.00 ns). The fluorescence lifetime histograms revealed four peaks. These peaks (0.18, 0.92, 2.50 and 3.80 ns) suggest the presence of NAD(P)H and flavins and show that sperm metabolism can be characterized using fluorescence lifetime imaging. The difference in fluorescence lifetime variation between the sexes is consistent with the notion that female animals alter the metabolism of sperm cells during storage. It is not consistent, however, with the idea that sperm metabolism represents a sexually selected character that provides females with information about the male genotype. 相似文献
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