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排序方式: 共有296条查询结果,搜索用时 171 毫秒
1.
Imaging of the optic disc and retinal nerve fiber layer: the effects of age, optic disc area, refractive error, and gender. 总被引:3,自引:0,他引:3
Christopher Bowd Linda M Zangwill Eytan Z Blumenthal Cristiana Vasile Andreas G Boehm Parag A Gokhale Kourosh Mohammadi Payam Amini Timothy M Sankary Robert N Weinreb 《Journal of the Optical Society of America. A, Optics, image science, and vision》2002,19(1):197-207
We cross-sectionally examined the relationship between age, optic disc area, refraction, and gender and optic disc topography and retinal nerve fiber layer (RNFL) measurements, using optical imaging techniques. One eye from each of 155 Caucasian subjects (age range 23.0-80.8 y) without ocular pathology was included. Measurements were obtained by using the Heidelberg Retina Tomography (HRT), the GDx Nerve Fiber Analyzer, and the Optical Coherence Tomograph (OCT). The effects of age were small (R2 < 17%) and were limited to specific HRT, GDx, and OCT parameters. Disc area was significantly associated with most HRT parameters and isolated GDx and OCT parameters. Refraction and gender were not significantly associated with any optic disc or RNFL parameters. Although effects of age on the optic disc and RNFL are small, they should be considered in monitoring ocular disease. Optic disc area should be considered when cross-sectionally evaluating disc topography and, to a lesser extent, RNFL thickness. 相似文献
2.
Gina‐Gabriela Bumbu Cornelia Vasile Maria Cristina Popescu Hristea Darie Gabrielle Charlotte Chianu Gheorghe Singurel Adrian Carpov 《应用聚合物科学杂志》2003,88(11):2585-2597
The compatibility of the hydroxypropyl cellulose (HPC) with maleic acid–vinyl acetate copolymer in the solid state was studied by thermogravimetry, thermo‐optical analysis, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and optical microscopy. It was established that physical interactions are prevalent in blends with a high content of HPC, whereas chemical interactions predominate in blends with a medium and low content of HPC. By increasing the temperature, the thermochemical reactions are favored. Thermal properties are dependent on the mixing ratio of the components. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2585–2597, 2003 相似文献
3.
The enzymatic degradation of poly(N‐isopropyl acrylamide) (PNIPAM) grafted to carboxymethylcellulose (CMC) copolymers with a cellulasic preparation (Trichoderma viride) was studied. The enzymatic activity of the cellulasic preparation against CMC and the grafted copolymers was determined by the Petterson–Porath method, while their reduced viscosity variation in the presence of the same preparation was also followed. It has been shown that the enzymatic degradation behavior depends on the copolymer composition and the reaction temperature. Reducing sugars analysis showed that the experimental values for the grafted copolymers were higher than the calculated ones. At 50°C, the enzymatic reaction is completed in about 20 min for the copolymers, whereas for CMC it takes more than 40 min. It can be concluded that their enzymatic degradation is facilitated by the presence of the PNIPAM grafts. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1383–1386, 2003 相似文献
4.
Localized Synthesis of Iron Oxide Nanowires and Fabrication of High Performance Nanosensors Based on a Single Fe2O3 Nanowire 下载免费PDF全文
Oleg Lupan Vasile Postica Niklas Wolff Oleksandr Polonskyi Viola Duppel Victor Kaidas Eugen Lazari Nicolai Ababii Franz Faupel Lorenz Kienle Rainer Adelung 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(16)
A composed morphology of iron oxide microstructures covered with very thin nanowires (NWs) with diameter of 15–50 nm has been presented. By oxidizing metallic Fe microparticles at 255 °C for 12 and 24 h, dense iron oxide NW networks bridging prepatterned Au/Cr pads are obtained. X‐ray photoelectron spectroscopy studies reveal formation of α‐Fe2O3 and Fe3O4 on the surface and it is confirmed by detailed high‐resolution transmission electron microscopy and selected area electron diffraction (SAED) investigations that NWs are single phase α‐Fe2O3 and some domains of single phase Fe3O4. Localized synthesis of such nano‐ and microparticles directly on sensor platform/structure at 255 °C for 24 h and reoxidation at 650 °C for 0.2–2 h, yield in highly performance and reliable detection of acetone vapor with fast response and recovery times. First nanosensors on a single α‐Fe2O3 nanowire are fabricated and studied showing excellent performances and an increase in acetone response by decrease of their diameter was developed. The facile technological approach enables this nanomaterial as candidate for a range of applications in the field of nanoelectronics such as nanosensors and biomedicine devices, especially for breath analysis in the treatment of diabetes patients. 相似文献
5.
The main object of the present paper is to discuss some extensions of certain integral operators and to obtain their order of convexity. Several other closely related results are also considered. 相似文献
6.
Daniela PatrascuAuthor VitaeIulia DavidAuthor Vitae Vasile DavidAuthor VitaeConstantin MihailciucAuthor Vitae Ioan StamatinAuthor VitaeJean CiureaAuthor Vitae Livia NagyAuthor VitaeGéza NagyAuthor Vitae Anton Alexandru CiucuAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(2):731-736
Iron(II) phthalocyanine (FePc) modified multi-wall carbon nanotubes paste electrodes (MWCNTPEs) were used as voltammetric sensors to selectively detect dopamine (DA) in the presence of serotonin (5-HT). The electrochemical behavior of DA at the new modified electrode was investigated using CV. The enhanced current response of DA indicates that FePc modification of the MWCNTPE surface results in a high catalytic activity for the redox reaction of DA. Differential pulse voltammetry was applied in detection of DA and 5-HT at FePc-MWCNTPE. The method parameters were optimized. Detection limit of 2.05 × 10−7 M was obtained for DA by using the electrocatalytic oxidation signal corresponding to the FeII/FeIII redox process. The separation between the peak potentials of DA and 5-HT is 170 mV which is large enough for the simultaneously, selective determination of the two chemical species in their mixtures. There was no electrochemical response for ascorbic acid (AA) added in the sample. The monoamine neurotransmitter measuring method has been tested in analyzing deproteinized serum samples. 相似文献
7.
8.
Sarni Suhaila Rahim Chrisina Jayne Vasile Palade James Shuttleworth 《Neural computing & applications》2016,27(5):1149-1164
Regular eye screening is essential for the early detection and treatment of the diabetic retinopathy. This paper presents a novel automatic screening system for diabetic retinopathy that focuses on the detection of the earliest visible signs of retinopathy, which are microaneurysms. Microaneurysms are small dots on the retina, formed by ballooning out of a weak part of the capillary wall. The detection of the microaneurysms at an early stage is vital, and it is the first step in preventing the diabetic retinopathy. The paper first explores the existing systems and applications related to diabetic retinopathy screening, with a focus on the microaneurysm detection methods. The proposed decision support system consists of an automatic acquisition, screening and classification of diabetic retinopathy colour fundus images, which could assist in the detection and management of the diabetic retinopathy. Several feature extraction methods and the circular Hough transform have been employed in the proposed microaneurysm detection system, alongside the fuzzy histogram equalisation method. The latter method has been applied in the preprocessing stage of the diabetic retinopathy eye fundus images and provided improved results for detecting the microaneurysms. 相似文献
9.
Vasile Dragan Author vitae 《Automatica》2011,47(1):122-126
In this paper, the problem of robust H∞ control is investigated for sampled-data systems with probabilistic sampling. The parameter uncertainties are time-varying norm-bounded and appear in both the state and input matrices. For the simplicity of technical development, only two different sampling periods are considered whose occurrence probabilities are given constants and satisfy Bernoulli distribution, which can be further extended to the case with multiple stochastic sampling periods. By applying an input delay approach, the probabilistic sampling system is transformed into a continuous time-delay system with stochastic parameters in the system matrices. By linear matrix inequality (LMI) approach, sufficient conditions are obtained, which guarantee the robust mean-square exponential stability of the system with an H∞ performance. Moreover, an H∞ controller design procedure is then proposed. An illustrative example is included to demonstrate the effectiveness of the proposed techniques. 相似文献
10.
In this paper, a process for 200 μm high-aspect-ratio micro-optical (HARM) structures fabricated by deep X-ray lithography
(DXRL) of polymethylislesuioane-based spin-on glass (SOG) thick films is presented. The SOG material used in the whole procedures
is polymethylsilsesquioxane (GR650), which is a kind of sol-gel derived material and can be cured at a reasonable low temperature
(75 °C). A technique to cast thick GR650 films was established in the overall process. After consolidation, the GR650 thick
films were machined to reach 200 μm uniformly. Then, as negative resists, the GR650 thick films were patterned directly by
DXRL. X-ray irradiated regions can be selectively retained with high structural resolution by development in an organic solvent,
such as methanol. Parameter screening was done to find minimum and maximum doses needed for patterning/cross-linking, to vary
development time, and to explore different film thickness. The whole process is a novel of technique to create HARM structures
based on SOG materials without using molds. This technique can be extended to considerably larger structural heights. Surface
and bulk compositions of the irradiated films were measured by XPS and Fourier transform infrared spectroscopy. Surface quality
by roughness testing system (WYKO RST) was investigated to fabricate the microstructure with a high-accuracy surface.
Received: 31 October 2001/Accepted: 23 January 2002
This work was partially supported by NSF/LEQSF (2001-04)-RII-02 grant “Micro/Nanodevices for Physical, Chemical and biological
Sensors”. 相似文献