CPC内聚光式集热器真空层传热的模拟研究

运用Fluent软件中的太阳加载模型,以新型CPC内聚光式集热器为研究对象,通过理论分析和数值模拟相结合的方法研究了环形空间真空层的传热特性,分析了不同环形空间压力和不同气体介质下CPC内聚光式集热器温度场的分布以及热损失特性。模拟结果表明,在太阳辐照度一定的情况下,环形空间压力越大,集热器热损失也就越大,当环形空间压力下降到1 Pa时,环形空间的热损失基本不再受环形空间压力的影响。研究结果可揭示环形空间内部的传热机理,确定CPC内聚光式集热器内合理的真空压力,为CPC内聚光式集热器结构参数的优化以及集热效率的提高提供可行性依据。

内聚光型太阳能光电-光热复合管的光学设计

根据非跟踪内聚光型太阳能光电-光热复合管的结构形式及其受光体的特殊需求,采用Winston的CPC设计原理,对圆管内具有特殊形状的半圆柱接收器的复合抛物面聚光器进行光学设计,得到了较为理想的聚光器设计曲线,并对结果进行数值仿真,给出各入射角的光线分布图和光强分布图。

内聚光膜式全玻璃真空太阳集热管真空品质表征方法

本文计算了内聚光膜式全玻璃真空太阳集热管在烘烤排气过程中的排气量,提出了一种定量表征其真空品质的方法,然后通过集热管高温烘烤———加速老化实验对其真空性能进行了验证,首次利用内聚光膜式集热管高温烘烤过程中铝膜温度随老化时间的变化曲线表征其真空性能,且效果良好。实践表明,这种定量分析结合实验验证的方法表征内聚光膜式集热管真空品质是行之有效的。

内聚光膜式全玻璃真空太阳集热管烘烤排气工艺研究

对内聚光膜式全玻璃真空太阳集热管进行了9组烘烤排气实验,通过对比各组集热管在烘烤排气过程中的排气量及分析高温烘烤———加速老化实验数据,得到了其烘烤排气最佳工艺参数。9组实验中,450℃/50 min,450℃/40 min,450℃/30 min及400℃/50 min四个工艺制作的集热管真空品质相差不多,优于其余五个工艺;单从集热管真空品质角度看,450℃/50min烘烤排气工艺最好,若从真空品质和制作成本两方面考虑,400℃/50 min是较好的工艺参数。

新V型内聚光CPC热管式真空管集热器的热性能

基于圆管型复合抛物聚光器(CPC)的研究,由于接受体和CPC反光板之间存在缝隙而造成大量漏光损失,设计了一种可以减少漏光损失和热损的新V型CPC反光板,并综合利用热管式真空管集热器的优越性,开发出一种新V型内聚光CPC热管式真空管集热器。首先给出了其设计结构,并对其进行传热分析,推导出该型集热器的集热效率、总热损系数的计算方法,再进行室外动态性能试验,测定了它的效率曲线,试验结果与理论计算值较符合。

CPC内聚光式热管集热管温度特性研究

为提高太阳能热水系统的输出温度,将CPC聚光技术应用于热管式真空集热管中,开发了一种新型的CPC内聚光式热管集热管。对该集热管建立数学模型,模拟计算其传热过程,获得了导热肋片温度、热管冷凝段温度等参数随太阳辐射强度的变化规律,并通过试验验证了数学模型的可靠性;与常规热管式真空管集热管传热特性相对比,证实了该集热管可大幅提高太阳能热水器输出温度。

新型内聚光中温太阳能集热器的设计研究

提出了一种新型内聚光中温太阳能集热器,构成该集热器的集热管采用了一种新的玻璃金属封接技术,并结合了内聚光板的优化设计和流道强化换热设计。该内聚光中温太阳能集热器具有光热转换效率较高、单位成本较低的优点,可广泛应用于中温太阳能热利用的场合。

一种非跟踪型太阳能复合聚光器的设计与实验研究

设计一种非跟踪型光电光热复合管以同时得到电能和热能,利用Matlab对聚光器曲线的形状进行优化并对结果进行数值仿真,对不同吸收体形状之间进行数据比较,得到最佳吸收体形状。给出不同入射角的光路图和下表面聚光比分布图,证明下表面得光也较均匀,可避免因高温热应力对太阳电池产生的损坏。最后实验测试下表面平均聚光比,与仿真的结果较为吻合。最后得出下表面三角形腰长为14.5 mm时最为合适并给出设计图。

真空管内聚光集热器光学性能研究

针对具有内部反射涂层和偏心吸收管的新型真空管内聚光集热器,建立了反映其结构的几何模型,并基于光线追迹法,依托光学分析软件TracePro对其光学性能进行了研究。通过模拟仿真分别得到了该集热器对太阳直射辐射和散射辐射的光学效率,并与传统真空管集热器进行了对比。此外还研究了径向入射角、轴向入射角、内玻璃管偏心距、反射涂层圆心角等参数对光学效率的影响。最后与实验结果进行对比验证,证明了该集热器具有突出的光学性能。

Confocal laser endomicroscopy in the “in vivo” histological diagnosis of the gastrointestinal tract

Recent technological advances in miniaturization have allowed for a confocal scanning microscope to be integrated into a conventional flexible endoscope,or into trans-endoscopic probes,a technique now known as confocal endomicroscopy or confocal laser endomicroscopy.This newly-developed technology has enabled endoscopists to collect real-time in vivo histological images or "virtual biopsies" of the gastrointestinal mucosa during endoscopy,and has stimulated significant interest in the application of this technique in clinical gastroenterology.This review aims to evaluate the current data on the technical aspects and the utility of this new technology in clinical gastroenterology and its potential impact in the future,particularly in the screening or surveillance of gastrointestinal neoplasia.

Software for automated classification of probe-based confocal laser endomicroscopy videos of colorectal polyps

AIM:To support probe-based confocal laser endomi-croscopy (pCLE) diagnosis by designing software for the automated classification of colonic polyps. METHODS:Intravenous fluorescein pCLE imaging of colorectal lesions was performed on patients under-going screening and surveillance colonoscopies, followed by polypectomies. All resected specimens were reviewed by a reference gastrointestinal pathologist blinded to pCLE information. Histopathology was used as the criterion standard for the differentiation between neoplastic and non-neoplastic lesions. The pCLE video sequences, recorded for each polyp, were analyzed off-line by 2 expert endoscopists who were blinded to the endoscopic characteristics and histopathology. These pCLE videos, along with their histopathology diagnosis, were used to train the automated classification software which is a content-based image retrieval technique followed by k-nearest neighbor classification. The performance of the off-line diagnosis of pCLE videos established by the 2 expert endoscopists was compared with that of automated pCLE software classification. All evaluations were performed using leave-one-patient- out cross-validation to avoid bias. RESULTS:Colorectal lesions (135) were imaged in 71 patients. Based on histopathology, 93 of these 135 lesions were neoplastic and 42 were non-neoplastic. The study found no statistical significance for the difference between the performance of automated pCLE software classification (accuracy 89.6%, sensitivity 92.5%, specificity 83.3%, using leave-one-patient-out cross-validation) and the performance of the off-line diagnosis of pCLE videos established by the 2 expert endoscopists (accuracy 89.6%, sensitivity 91.4%, specificity 85.7%). There was very low power (< 6%) to detect the observed differences. The 95% confidence intervals for equivalence testing were:-0.073 to 0.073 for accuracy, -0.068 to 0.089 for sensitivity and -0.18 to 0.13 for specificity. The classification software proposed in this study is not a "black box" but an informative tool based on the query by example model that produces, as intermediate results, visually similar annotated videos that are directly interpretable by the endoscopist. CONCLUSION:The proposed software for automated classification of pCLE videos of colonic polyps achieves high performance, comparable to that of off-line diagnosis of pCLE videos established by expert endoscopists.

High concentration of calcium ions in Golgi apparatus

The interphase NIH3T3 cells were vitally fluorescentstained with calcium indicator fluo-3 and Glogi probe C6NBD-ceramide, and then the single cells were examined by laser scanning confocal microscopy (LSCFM) for subcellular distributions of Ca2+ and the location of Golgi apparatus. In these cells, the intracellular Ca2+ were found to be highly concentrated in the Golgi apparatus. The changes of distribution of cytosolic high Ca2+ region and the Golgi apparatus coincided with the cell cycle phase.In calcium free medium, when the plasma membrane of the cells which had been loaded with fluo-3/AM were permeated by digitonin, the fluorescence of the Golgi region decreased far less than that of the cytosol. Our results indicated that the Glogi lumen retained significantly high concentration of free calcium.

A Confocal Endoscope for Cellular Imaging

Since its inception, endoscopy has aimed to establish an immediate diagnosis that is virtually consistent with a histologic diagnosis. In the past decade, confocal laser scanning microscopy has been brought into endoscopy, thus enabling in vivo microscopic tissue visualization with a magnification and resolution comparable to that obtained with the ex vivo microscopy of histological specimens. The major challenge in the development of instrumentation lies in the miniaturization of a fiber-optic probe for microscopic imaging with micron-scale resolution. Here, we present the design and construction of a confocal endoscope based on a fiber bundle with 1.4-μm lateral resolution and 8-frames per second(fps) imaging speed. The fiber-optic probe has a diameter of 2.6 mm that is compatible with the biopsy channel of a conventional endoscope. The prototype of a confocal endoscope has been used to observe epithelial cells of the gastrointestinal tracts of mice and will be further demonstrated in clinical trials. In addition, the confocal endoscope can be used for translational studies of epithelial function in order to monitor how molecules work and how cells interact in their natural environment.

In vitro toxicologic study of chitin short fiber reinforced polycaprolactone composite

Objective: To investigate the cytotoxicity and cytocompatibility of chitin fiber reinforced polycaprolactone composite in vitro in order to provide useful scientific basis for clinical application. Methods: Cell morphology observation, MTT and DNA assay were used to evaluate the influence of the composite on the morphology, growth and proliferation of cultured L-929 cells. Results: The composite did not impair the morphology of cultured cells in vitro. MTT and DNA assay demonstrated that the growth and proliferation of the cultured cells were not significantly inhibited by the composite. Conclusion : The composites have fine cytocompatibility and are safe for clinical use of reconstruction of chest wall defects.

Uses of probe-based confocal laser endomicroscopy:Responses to a question to practitioners

Confocal laser endomicroscopy is a novel imaging technology,which allows realtime visualization and inter-pretation of microscopic details in live tissues. Although several potential uses have been identified for this technology,no data are available regarding its real-worlduses. We report the results of an email-based survey of experts in North America regarding their use of the technology.

Alternative Scheme for Generation of Atomic Schrdinger Cat States and Entangled Coherent States in an Optical Cavity

We propose an alternative scheme for generation of atomic Schrodinger cat states in an optical cavity. In the scheme the atoms are always populated in the two ground states and the cavity remains in the vacuum state. Therefore, the scheme is insensitive to the atomic spontaneous emission and cavity decay. The scheme may be generalized to the deterministic generation of entangled coherent states for two atomic samples. In contrast with the previously proposed schemes of [Commun. Theor. Phys. 40 （2003） 103 and Chin. our scheme is greatly shortened and thus the deeoherence can Phys. B 18 （2009） 1045], the required interaction time in be effectively suppressed.

Biocompatible organic dots with aggregation-induced emission for in vitro and in vivo fluorescence imaging

Fluorescent probes play a key role in modern biomedical research. As compared to inorganic quantum dots (QDs) composed with heavy metal elements, organic dye-based fluorescent nanoparticles have higher biocompatibility and are richer in variety. However, traditional organic fluorophores tend to quench fluorescence upon aggregation, which is known as aggregation-caused quenching (ACQ) effect that hinders the fabrication of highly emissive fluorescent nanoparticles. In this work, we demonstrate the synthesis of organic fluorescent dots with aggregation-induced emission (AIE) in far-red/near-infrared (FA/NIR) region. A conventional ACQ-characteristic fluorescent dye, 3,4:9,10-tetracarboxylic perylene bisimide (PBI), is converted into an AIE fluorogen through attaching two tetraphenylethylene (TPE) moieties. The fluorescent dots with surface folic acid groups are fabricated from PBI derivative (DTPEPBI), showing specific targeting effect to folate receptor-overexpressed cancer cells. In vivo studies also suggest that the folic acid-functionalized AIE dots preferentially accumulate in the tumor site through enhanced permeability and retention (EPR) effect and folate receptor-mediated active targeting effect. The low cyto-toxicity, good FR/NIR contrast and excellent targeting ability in in vitro/in vivo imaging indicate that the AIE dots have great potentials in advanced bioimaging applications.

Blue light-emitting polyfluorenes containing dibenzothiophene-S,S-dioxide unit in alkyl side chain

Blue light-emitting polyfluorenes containing dibenzothiophene-S,S-dioxide(SO) unit in alkyl side chain(PF-FSOs and PF-CzSOs) were synthesized. All the polymers show high thermal stability with the decomposition temperatures over400 °C. The highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital(LUMO) energy levels of the copolymer slightly decrease with the increase of SO content in side chain. PL spectra of the polymers show slightly red shift and broadening with the increase of solvent polarities, indicating unremarkable intramolecular charge transfer(ICT) effect in the polymers containing SO unit in alkyl side chain. EL spectra of the polymers are almost unchanged in the current densities from 100 to 400 mA cm.2, indicating the superb EL stability of the resulted polymers. The EL spectra of the copolymers exhibit obvious blue-shift and narrowing with the CIE of(0.18, 0.11) for PF-FSO10 and(0.17, 0.11) for PF-CzSO10, respectively,compared with PF-SO10 containing SO unit in main chain with the CIE of(0.16, 0.17) and PFO with the CIE of(0.18, 0.18).The superior device performances were obtained with the luminous efficiency(LEmax) of 1.17 and 0.68 cd A.1 for PF-FSO15 and PF-CzSO20, respectively, compared with the LEmax of 0.37 cd A.1 for PFO. The results indicate that linking SO unit to alkyl side chain of the polyfluorene is a promising strategy for efficient blue light-emitting polymers.

POWER TO THE PEOPLE

Hydropower changes lives in Equatorial GuineaBefore the Djiploho Hydropower Station（DHS）was built,Djiploho was a secluded forest village in Equatorial Guinea.The change has shone a spotlight on the Wele River,now quite literally the center of power.Liu Bao,chief supervisor of the DHS project,