A Risk Score System for Myopia Symptom Warning

Myopia is the leading cause of visual impairments worldwide. Some studies revealed that visual experience in early life affected the final myopia, indicating that environmental factors play an impellent role in the development of myopia. However, risk factors of myopia are still not identified among adolescents in China. A total of 4104 cases of myopia symptom and 3306 emmetropia controls were selected from students in primary and middle schools in Wuhan in 2008. We identified the risk factors associated with myopia symptom by multivariate logistic regression in this cross-sectional study and constructed a risk score system for myopia symptom. The value of the area under the receiver operating characteristic curve (ROC) was 0.735. Furthermore, we followed up 93 students aged 7-9 years for one year and calculated the total points using the score system. We found no significant difference between the final myopia symptom and the results predicted by the total points by pair chi-square test (P>0.05). The score system had a modest ability to estimate the risk factors of myopia symptom. Using this score system, we could identify the students who are at risk of myopia symptom in the future according to their behaviors and environmental factors, and take measures to slow the progress of myopia symptom.

Visualizing Complex Anatomical Structure in Bamboo Nodes Based on X-ray Microtomography

In recent years,bamboo has been widely used in a broad range of applications,a thorough understanding of the structural characteristics of bamboo nodes is essential for better processing and manufacturing of biomimetic materials.This study investigated the complex anatomical structure for the nodes of two bamboo species,Indocalamus latifolius(Keng)McClure and Shibataea chinensis Nakai,using a high-resolution X-ray microtomography(μCT).The results show that the vascular bundle system in the nodal region of I.latifolius and S.chinensis is a net-like structure composed of horizontal and axial vascular bundles.Furthermore,the fiber sheath surrounding metaxylem vessels tended to be shorter in the tangential direction.This structure of bamboo nodes facilitates the tangential and axial transport of moisture and nutrients.The anatomical structure of I.latifolius and S.chinensis nodes has obvious differences,especially in the arrangement of vascular bundles.Vascular bundle frequency was significantly higher in S.chinensis nodes than in I.latifolius nodes.These findings indicate thatμCT is a nondestructive three-dimensional imaging method that can used to examine the anatomical structure of bamboo nodes.

From structural to functional imaging:the developments of clinical ophthalmology optical coherence tomography

Starting with introduction of basic concept of optical coherence tomography(OCT) techniques,this paper focuses on a detailed review of ophthalmic OCT instruments and their clinical applications. As one of the most important inventions of ophthalmology instruments,OCT has become a standard imaging tool for daily ophthalmic diagnosis. The imaging capability has been significantly improved during the past ~ 30 years. In this article,several representing systems which have made significant contributions to OCT developments will be reviewed in details. For each system,the system configuration will be discussed first,follow ed by a brief introduction of their clinical applications. The review concludes with discussions on potential directions of OCT developments and expectations for further improvements of OCT imaging capabilities.

电子背散射衍射技术的撞屏失误和试样放置注意事项

针对电子背散射衍射探测器的磷屏距离试样较近,操作时容易撞屏的问题,分析了电子背散射衍射技术的风险点和两种防撞报警功能,探讨了撞屏对探测器的影响,总结了试样放置时的注意事项,分析了防撞功能的局限性。结果表明:除了对风险认识不足外,两次事故均源于不恰当地使用软件功能,使试样台出现过大幅度且快速移动;梳理操作风险、更为谨慎的操作和更规范的管理可以避免该类问题再次发生。

基于CT三维重建的高阶煤孔裂隙结构综合表征和分析

为有效研究煤的孔裂隙结构特征,实现对煤的孔裂隙结构的定性定量表征和分析。以内蒙古巴彦高勒煤矿311102运输巷的煤样为研究对象,基于ZEISS Xradia510 Versa X射线显微镜扫描得到的CT数据,结合三维可视化软件AVIZO中内置数学算法,提出了煤的孔裂隙结构定量表征的方法,并建立了煤的三维孔裂隙结构模型和具有拓扑结构的孔隙网络简化模型。通过本文提出的方法,对巴彦高勒煤矿煤样的孔裂隙微观参数——孔径大小、孔体积、孔隙率、配位数、喉道长度等进行了统计分析。研究表明:在微米的尺度下,内蒙古巴彦高勒煤矿的煤样以大孔为主,并伴有网状的割理裂隙,有效孔隙率为10.34%,通过孔隙网络模型统计出的孔隙数为12 834,喉道数为432及其他的微观结构参数。

加速电压和束流强度对热敏感材料扫描电镜图像的影响

扫描电镜为材料形貌和成分分析中普遍使用的仪器,但部分材料由于导电性及导热性差,在实际观测过程中容易发生形貌变形。本实验以蓝绿藻、有机高分子和金属有机框架材料为样品,研究了不同加速电压和束流条件下对观测样品形貌的影响。实验结果表明对于热敏感材料,电子束总能量在一定范围内时,与束流相比,加速电压对材料的影响更大,优先采用降低加速电压更合适。

AI辅助中国偏远基层社区老年人青光眼筛查对医疗费用和医保基金的影响:基于海南省昌江黎族自治县的卫生经济学分析

目的预测中国偏远基层地区老年原发性闭角型青光眼(PACG)患者人群人工智能(AI)辅助筛查对医疗费用、医保基金支出的影响。方法纳入海南省昌江黎族自治县19395名65岁及以上老年人,借鉴浙江温州青光眼人群筛查的卫生经济学模型,将PACG按照严重程度分为原发性房角关闭可疑状态、原发性房角关闭、PACG、单眼致盲和双眼致盲5个状态,并结合青光眼相关文献提供的流行病学、转移概率和治疗依从性、筛查和转诊依从性、AI筛查的敏感性和特异性以及县中西医结合医院2016—2019年医疗费用数据和医疗保险报销比例对卫生经济学模型进行调整,拟合昌江县PACG患者在AI辅助筛查与无筛查2种方案下未来15年内的健康转归、医疗费用与医保基金支出情况。结果以无筛查方案为对照,实施AI辅助PACG筛查,未来15年内可延缓患者疾病进展,减少PACG患者134例和盲患者9例,分别占43%和50%。在AI辅助筛查方案下,阳性患者的早诊断、早治疗短期内将引起医疗费用和医保基金支出过快增长,超过同时期无筛查方案下的费用。从第3年开始,医保基金支出将由增长扭转为下降,控费效应显现,从第10年开始,医疗费用同样发生由增长变为下降的转折。而在无筛查方案下,由于大量PACG患者进展至晚期,医疗费用持续上涨,并于第14年将超过筛查方案的医疗费用。结论卫生经济学分析预测PACG人群AI辅助筛查在中国偏远基层地区不仅具有良好的成本效益,而且可延缓疾病进展,长期可节省医疗费用与医保基金支出。

层-层正交角联锁机织物及其复合材料的结构及其层切破坏机制研究

采用无损高分辨率X射线成像(显微X-CT)技术对层-层正交角联锁机织物以及复合材料内部结构进行分析,并研究了层间剪切强度与结构之间的关系;通过三维重构展现了机织物的层-层正交角联锁的微观结构,观察到机织物内部的单丝扭转、挤压现象;依据机织复合材料中孔隙和高密度杂质在三维空间的分布,计算了其相应的占比。结果表明:层间剪切实验后的机织复合材料虽然宏观形貌保持了良好的完整性,但内部存在孔隙变形、分层、纤维弯曲、片层断裂等现象;层-层正交角联锁机织结构有效提高了复合材料的层间力学性能,内部的缺陷对复合材料的力学性能有较大的影响;无损高分辨X射线成像技术是研究纤维增强复合材料内部复杂结构特性的有利手段。

有机无机杂化钙钛矿样品的扫描电镜成像探讨

有机无机杂化钙钛矿(Organic-inorganic hybrid perovskites,OIHP)由于易受电子辐射损伤,在利用电镜对其进行材料学研究分析时具有一定的局限性。在利用透射电镜对其分析时建议使用高加速电压,但在利用扫描电镜分析时有建议用高加速电压,也有建议用低加速电压,观点不一。本研究以有机无机杂化钙钛矿MAPbBr3为代表样品,对OIHP利用扫描电镜成像条件进了探讨。

高新技术中小企业的战略优势与劣势-战略发展分析

工业国家的中小型高科技企业有很大的创新潜力,同时对所在地区的经济发展起到了积极的作用。由于公司规模大小不一,所以很难有时间从众多的案例中找到具体的管理技巧。本文主要对创新公司的战略等问题的具体内容和方法进行调查研究。

工业CT扫描：快速完成模塑鉴定

当一副新的漠具安装到位岳，需要经过多次调试才能获得合格的制品。而制品与原设计是否相符？内外是否有缺陷？……所有这些部需要有可靠的检测手段做出鉴定。工业CT扫描技术则大大缩短？这一鉴定过程，为模具和塑料制品的开发赢得了宝贵的时间。

掩膜级测量为闪存设计预测成像质量

闪存不断推动着器件尺寸等比例缩小的进程,高数值孔径浸没式光刻使得45nm及以下技术节点成为可能。一些掩膜参数对于成像性能有很重要的影响,并且曝光前掩膜的空间成像可以用于定义成像质量。

ArF浸没式光刻在55nm逻辑器件制造中的优势(英文)

通过比较干法和浸没光刻技术在超越焦深(DOF)提高方面的一些主要特点,举例说明了采用浸没式光刻技术的许多优势。浸没式光刻技术同干法光刻技术比较起来改善了关键尺寸一致性(CDU)又避开了必需而强硬的分辨率提高技术(RET)。因此利用浸没式光刻技术能够有效地减少光学邻近校正(OPC)的麻烦。就成像技术而言,我们研究了光刻技术对畸变的敏感性和浸没式光刻技术光源光谱带宽对强光相对曝光量对数E95波动性能的优势。去年已经见证了被认为对浸没光刻技术在批量生产中主要难题的套刻精度、缺陷控制和焦平面精度方面有效的改进。如今55nm逻辑器件的生产制造技术要求的挑战已经得到了满足。浸没光刻技术的成就包括抗蚀剂圆片内10nm套刻精度和圆片间20nm的套刻精度,每一圆片上低于10个缺陷以及在整个圆片上40nm以内的焦平面误差。我们形成了一个顶涂层抗蚀剂工艺。总之,浸没光刻技术是55nm节点逻辑器件最有希望的制造生产技术,它可提供与干法ArF光刻技术在CDU控制、套刻性能和焦平面精度方面等效的解决方案,缺陷程度没有增加。NEC电子公司今年采用浸没光刻技术完成了55nm逻辑器件"UX7LS"的开发和试生产并形成这种UX7LS的批量生产光刻技术。

Polymeric photonic molecule super-mode lasers on silicon

Optically coupled microcavities have emerged as photonic structures with promising properties for investigation of fundamental science as well as for applications.We report on the fabrication and spatially resolved spectroscopy of on-chip photonic molecule(PM)lasers consisting of two coupled,dye-doped polymeric microdisks on a silicon substrate.We investigate the fundamental lasing properties with focus on the spatial distribution of modes,the coupling dependent suppression of lasing modes,and in particular the application-oriented operation of these devices in aqueous environments.By depositing an additional polymer layer onto the lithographically structured cavities made of dye-doped poly(methyl methacrylate),coupling-gap widths below 150 nm with aspect ratios of the micro-/nanostructure exceeding 9:1 are achieved.This enables strong optical coupling at visible wavelengths despite relatively small resonator radii of 25 μm.The lasing properties of dye-doped PMs are investigated using spatially resolved micro-photoluminescence(μ-PL)spectroscopy.This technique allows for the direct imaging of whispering-gallery modes(WGMs)in the photonics molecules.For subwavelength coupling gaps,we observe lasing from delocalized eigenstates of the PMs(termed in the following as super-modes).Using size-mismatched cavities,the lasing mode suppression for different coupling-gap widths is investigated.We further demonstrate single-mode lasing operation in aqueous environments with PMs,which are realized on a low-cost,polymer-on-silicon platform.

Towards in-situ diagnostics of multi-photon 3D laser printing using optical coherence tomography

In recent years,multi-photon 3D laser printing has become a widely used tool for the fabrication of micro-and nanostructures for a large variety of applications.Typically,thorough sample characterisation is key for an efficient optimisation of the printing process.To date,three-dimensional microscopic inspection has usually been carried out on finished 3D printed microstructures,that is,using ex-situ approaches.In contrast,in-situ 3D characterization tools are desirable for quickly assessing the quality and properties of 3D printed microstructures.Along these lines,we present and characterise a Fourier-domain optical coherence tomography(FD-OCT)system that can be readily integrated into an existing 3D laser lithography setup.We demonstrate its capabilities by examining different 3D printed polymer microstructures immersed in a liquid photoresist.In such samples,local reflectivity arises from the(refractive-index)contrasts between the polymerised and non-polymerised regions.Thus,the refractive index of the printed material can be extracted.Furthermore,we demonstrate that the reflectivity of polymer-monomer transitions exhibits time-dependent behaviour after printing.Supported by transfer-matrix calculations,we explain this effect in terms of the time-dependent graded-index transition originating from monomer diffusion into the polymer matrix.Finally,we show exemplary 3D reconstructions of printed structures that can be readily compared with 3D computer designs.

Optical imaging of post-embryonic zebrafish using multi orientation raster scan optoacoustic mesoscopy

Whole-body optical imaging of post-embryonic stage model organisms is a challenging and long sought-after goal.It requires a combination of high-resolution performance and high-penetration depth.Optoacoustic(photoacoustic)mesoscopy holds great promise,as it penetrates deeper than optical and optoacoustic microscopy while providing high-spatial resolution.However,optoacoustic mesoscopic techniques only offer partial visibility of oriented structures,such as blood vessels,due to a limited angular detection aperture or the use of ultrasound frequencies that yield insufficient resolution.We introduce 3601 multi orientation(multi-projection)raster scan optoacoustic mesoscopy(MORSOM)based on detecting an ultra-wide frequency bandwidth(up to 160 MHz)and weighted deconvolution to synthetically enlarge the angular aperture.We report unprecedented isotropic inplane resolution at the 9–17μm range and improved signal to noise ratio in phantoms and opaque 21-day-old Zebrafish.We find that MORSOM performance defines a new operational specification for optoacoustic mesoscopy of adult organisms,with possible applications in the developmental biology of adulthood and aging.

Scanning electron microscopy imaging of single-walled carbon nanotubes on substrates

Scanning electron microscopy （SEM） plays an indispensable role in nanoscience and nanotechnology because of its high efficiency and high spatial resolution in characterizing nanomaterials. Recent progress indicates that the contrast arising from different conductivities or bandgaps can be observed in SEM images if single-walled carbon nanotubes （SWCNTs） are placed on a substrate. In this study, we use SWCNTs on different substrates as model systems to perform SEM imaging of nanomaterials. Substantial SEM observations are conducted at both high and low acceleration voltages, leading to a comprehensive understanding of the effects of the imaging parameters and substrates on the material and surface-charge signals, as well as the SEM imaging. This unified picture of SEM imaging not only furthers our understanding of SEM images of SWCNTs on a variety of substrates but also provides a basis for developing new imaging recipes for other important nanomaterials used in nanoelectronics and nanophotonics.

Exogenous Hematin Alleviates Mercury-induced Oxidative Damage in the Roots of Medicago sativa

In the present study, we evaluated the protective effect of exogenous heme oxygenase-1 （HO-1 EC 1.14.99.3） inducer hematin against mercury-induced oxidative damage in the roots of Alfalfa （Medicago sativa L.）. Plants exposed to mercury （HgCl2） exhibited a significant increase of lipid peroxidation, as well as inhibition of root elongation. However, hematin （50 μM） supplementation to HgCl2 （100 μmol/L） treated plants effectively reduced the lipid peroxidation and partially increased the root elongation. These responses were mimicked by the application of aqueous solution of carbon monoxide （CO） with 50% saturation. Also, treatment with hematin could result in the potent induction of HO-1 transcript in the root tissues, as detected 12h following treatment. Moreover, the activation of anti-oxidant enzyme, including glutathione reductase, monodehydroascorbate reductase and superoxide dismutase activities, and the decrease of lipoxygenase activity, were induced by hematin at 12h or 24h, which was further confirmed by histochemical staining for the detection of lipid peroxidation and loss of membrane integrity. Whereas, ascorbate peroxidase and guaiacol peroxidase isozyme activities or their transcripts were reduced, respectively, indicating that hydrogen peroxide might act as a signal to mediate Hg- tolerance at the beginning of treatment. The ameliorating effects of hematin were specific, since the CO scavenger hemoglobin differentially reversed the above actions. Taken together, our results suggested that hematin exhibits a vital role in protecting the plant against Hg-induced oxidative damage.

Quantitative Ore Analysis Solution

Use of the scanning electron microscope (SEM) to characterize ores provides mineralogists and metallurgists with invaluable information for the optimisation of processes. Manually obtaining relevant information such as, for example, mineral coatings that may interfere with flotation, mineral separations, the location of values, mineralogical or process reasons for low recovery, etc, can be exhausting and time consuming. For this reason, automated SEM methods for mineralogical characterisation have been devised. These methods rely on qualitative analyses of the samples using EDX or BSD grey levels to classify the phases present. The non-quantitative nature of the analyses means that other techniques, such as electron microprobe analysis (EMPA), must be used in conjunction with the SEM to obtain quantitative information of the sample. To overcome this limitation, Carl Zeiss has devised a method for the quantitative analysis of the mineralogy of any ore or ore-derived processed material; allowing for the full quantitative evaluation of a resource to be performed automatically by the SEM.

A general mechanism of grain growth-Ⅱ: Experimental

The formed microstructure inside polycrystalline materials strongly influences their practical performances,which process is mostly dominated by grain growth behaviors.However,the general evolution of grain growth behaviors,especial for the occurrence of abnormal grain growth and stagnant growth,remains ambiguous despite decades of efforts.Here,we investigate systematically the general evolution of grain growth behaviors by combining a new grain growth theory with grain growth experiments in SrTiO_(3) polycrystalline materials.The results demonstrate that the observed evolution of grain growth behaviors is in accord with the theoretical predictions,which reveals that the abnormal and stagnant behaviors of grain growth may intrinsically occur in polycrystalline systems due to the existence of nonzero step free energy for grain growth.Furthermore,the general growth theory reveals that normal grain growth results from the roughening transition of grain boundaries which corresponding to step free energy equal to zero.Besides the lower GB energy as commonly believed,the narrower grain size distribution is revealed to play an important role on the thermal stability of grains,which may lead to the counter-intuitive phenomenon of smaller nano-sized grains with higher thermal stability as recently reported in the literature.The general,quantitative growth theory may offer an accurate guidance for the microstructural design with optimal physical properties in polycrystalline materials.