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排序方式: 共有252条查询结果,搜索用时 31 毫秒
101.
This paper describes the development of novel particle-based fluorescence resonance energy transfer (FRET) sensors to quantify the concentration and monitor the binding affinity of carbohydrates and glycoproteins to lectins, which are carbohydrate binding proteins. The sensing approach is based on FRET between fluorescein (donor)-labeled lectin molecules, adsorbed on the surface of micrometric polymeric beads, and polymeric dextran molecules labeled with Texas Red (acceptor). The FRET efficiency of the donor-acceptor pair decreases in the presence of carbohydrates or glycoproteins that compete with the Texas Red-labeled dextran molecules on the lectinic binding sites. The inhibitory effect is concentration and time dependent. The sensing technique enables the discrimination between carbohydrates and glycoproteins based on their binding affinity to the FRET sensing particles as well as quantitative analysis of carbohydrates and glycoproteins in aqueous samples. In the future, the newly developed sensors could enable screening glycoprotein-based drugs for their binding affinity toward selective receptors. 相似文献
102.
We describe the experimental realization of an all-optical imaging system with an extended depth of field (DOF). The core of the system is a phase mask consisting of 16 Fresnel lenses (FLs) that are spatially multiplexed and mutually exclusive. Because each FL, in tandem with the primary lens, is designed to produce a sharp image for a specific object plane location, jointly the FLs achieve a wide DOF. However, the resultant image exhibits reduced resolution. The acquired image, onto which we did not apply any postprocessing, clearly is sharper than that acquired with a clear-aperture imaging system with the same pupil size. 相似文献
103.
We give an explicit construction of a large subset \({S \subset \mathbb{F}^n}\) , where \({\mathbb{F}}\) is a finite field, that has small intersection with any affine variety of fixed dimension and bounded degree. Our construction generalizes a recent result of Dvir and Lovett (STOC 2012) who considered varieties of degree one (that is, affine subspaces). 相似文献
104.
Marcus J. Smith Qingji Zeng Evan Lafalce Shengtao Yu Shuaidi Zhang Zeev Valy Vardeny Vladimir V. Tsukruk 《Advanced functional materials》2019,29(30)
This study reports a facile method for the assembly of large, array style, coupled dye‐doped microsphere resonators by template‐assisted, in which an aqueous suspension of colloidal microspheres assemble on a patterned template. By exploiting the high resolution of 3D (two‐photon) lithography derived templates, closely packed large arrays, hundreds to thousands of dimers with controlled gap spacing, only limited by the size of the substrate can be achieved. Dye‐doped emissive microspheres with Q‐factors >2.5 × 102 can be achieved and trapped into predetermined cavity positions, thereby controlling the distance between adjacent microspheres. This design allows to scale down dimer spacing from usual 400 nm for traditional photolithography to very small spacing of 50 nm. It is found that exciting individual microspheres in the ensemble shows intense optical cavity modes, whereas closely coupled pairs show controlled mode splitting. Coupling between photoluminescent microspheres is strongly influenced by the gap distance, with strong coupling, equating to normal mode splitting, arising as the gap distance is reduced below traditional sub‐micrometer scale. The coupled dimer assemblies are promising candidates for advancing the development of large‐area coupled nanophotonic structures, beyond the spatial resolution‐limited photolithographical derived arrays. 相似文献
105.
Yaxin Zhai Chuan Xiang Sheng Chuang Zhang Zeev Valy Vardeny 《Advanced functional materials》2016,26(10):1617-1627
Studying the room temperature broadband ultrafast transient response of photoexcitations in three perovskite films, namely MAPbI3, MAPbI1.1Br1.9, and MAPbI3?xClx (MA = CH3NH3), allowed unravelling the branching ratio between photogenerated carriers and excitons, a key factor for optoelectronic applications of perovskites. An instantaneously generated mid‐IR photoinduced absorption (PA) band, PA1 is observed in all three perovskites, as well as a strong derivative‐like band of photoinduced bleaching (PB) and PA (PA2) close to the corresponding absorption band edge. From the distinguished different decay dynamics of the PA bands in MAPbI3, PA1 is interpreted as due to the exciton transition, whereas PA2 and PB are due to band‐filling effect caused by the photocarriers. In contrast, all bands in MAPbI1.1Br1.9 and MAPbI3?xClx share the same dynamics and are therefore due to the same species, namely photogenerated excitons. The transient photoinduced polarization memory (POM) for both excitons and photocarriers as well as the steady‐state photoluminescence (PL) emission are observed in MAPbI3, but not in MAPbI1.1Br1.9 and MAPbI3?xClx because they possess cubic symmetry at room temperature. The estimated long excitons diffusion length (≈150 nm) in MAPbI3 opens up the possibility of photocarriers generation at interfaces and grain boundaries even when the exciton binding energy is large compare to kBT. 相似文献
106.
107.
In the present paper, 188 prokaryote genomes are classified by separately calculating the compositional spectra for the coding and the non-coding parts of the genomes. For each subsequence, the compositional spectrum is transformed into the corresponding point in a vector space. This enables the categorization of genomes into meaningful groups by a formal method. Repeated clustering performed for the coding and the non-coding genome parts makes it possible to estimate the true number of the genome clusters. The method we propose is based on a new application of external cluster validation indexes and on the misclassified quantities obtained in the process of repeated clustering. Besides, we have constructed additional data embedding into the appropriate Euclidean space only on the basis of the distances between compositional spectra. Biological evaluation of the results obtained for the 4-letter and the 2-letter alphabets substantiates the appropriateness of the resulting cluster-based classification. 相似文献
108.
Abstract Diffractive optical elements able to generate on-axis (zero-order) phase as well as amplitude distributions are described. The proposed elements are surface-relief plates, that is phase-only elements, that are based on concepts of computer-generated masks followed by lithographic and etching processes. The proposed encoding method assumes variable spatial partitioning of the cell and a fixed phase value allocated to each subcell. This method requires the minimal number of etching levels needed for full representation of the wave front, that is three, but can be applied with improved efficiency using more etching levels. The reconstructed amplitude and phase distributions contain some noise owing to the encoding process. Discussion of the error sources is given. 相似文献
109.
Hoi-Kok Cheung Wan-Chi Siu Dagan Feng Zhiyong Wang 《Signal Processing: Image Communication》2010,25(3):143-162
Conventional hybrid video coding systems rely on the assumption that the brightness is constant. This does not take inter-frame brightness variations into consideration during motion estimation and compensation processes. Under the influence of inter-frame lighting variations like camera flashes, video motion activities are not accurately estimated and the pixel prediction is poor which directly increases the bits for prediction error coding. In this paper, we propose an efficient algorithm based on the retinex-like system which allows inter-frame brightness being normalized before applying the conventional motion estimation and compensation. Experimental results show that our approach is superior to all similar approaches in the literature and demonstrate that our proposed system is very robust against the inter-frame brightness variations. Further experimental works have been done using the verification models of the MPEG-4 and the H.264 on sequences with brightness variations, results of which show that our proposed system outperforms these coding systems, including the weighted prediction feature in H.264, which were specifically designed for this purpose. 相似文献
110.
A new technology for remote measuring of vibration sources was recently developed for industrial, medical, and security-related applications [Int. Appl. Patent No: PCT/IL2008/001008]. It requires relatively expensive equipment, such as high-speed complementary metal oxide semiconductor (CMOS) sensors and customized optics. In this paper, we demonstrate how the usage of a simple personal computer (PC) mouse as an optical system composed of a low-power laser and a CMOS circuitry on the same integrated circuit package, can be used to monitor heartbeat from the wrist. The method is based on modifying the mouse optical system in such a way that it will recognize temporal change in skin's vibration profile, generated due to the heart pulses, as mouse movement. The tests that were carried out show a very good correlation between the heartbeat rate measured from human skin and the reference values taken manually. 相似文献