基于JPEG图像的无线胶囊内窥镜的设计

为了检测胃肠(GI)道疾病,设计并研制了一种新型的基于JPEG格式的数字式无线胶囊内窥镜(WCE)系统。胶囊内窥镜的直径为12mm,长28mm,非常易于吞服。胶囊内窥镜在人体肠道的蠕动作用下顺着消化道向下运动,同时获得分辨率为320×240的内窥镜图像,图像被压缩为JPEG格式后直接采用数字信号无线传出体外,无需进行D/A转换。数据被体外的接收盒接收存储,然后由图像分析软件进行再现、分析、诊断等处理。在用猪小肠模拟人体肠道的离体实验中,该胶囊内窥镜系统清晰地再现了猪小肠内部的图像。与基于Bayer格式模拟信号的胶囊内窥镜相比,数字信号抗干扰能力强,图像更加清晰,将有助于提高临床胃肠道疾病的诊断率。     

奥林巴斯“找回自己”

靠医疗发家的奥林巴斯在中国意外地收获了消费电子市场。为了跑得更快,它决定修补自己的另外一条短腿——在中国做大医疗事业这一老本行。也许不久后,去医院进行内窥镜检查就不会那么痛苦了,你只需吞下一个直径11毫米的胶囊。这个"异想天开"的胶囊即将由一家日本公司——奥林巴斯推向市场。7月初,奥林巴斯(中国)有限公司总经理河原东告诉《商务周刊》:"胶囊内镜很快就会进入中国并应用于临床,现在正在办理手续上的审批过程,最快今年内产品将在国内上市。"     

特殊冲孔保鲜膜

日本富士技术公司的最新产品——特殊冲孔保鲜薄膜最近开始正式投放市场。这种保鲜薄膜是先在人造丝无纺布上叠压一层低密度聚乙烯薄膜,然后,利用该公司发明的一种特析冲孔技术——熔孔有孔加工方法在薄膜上冲出许多直径为100～450微米的小     

非接触式眼压计压平角膜过程的数值模型研究

通过采用双向流固耦合的数值仿真技术,建立了一个非接触式眼压计压平角膜过程的三维瞬态数值模型,研究了非接触式眼压计工作时角膜外流场的流动状态以及不同眼压角膜的动态变化过程,结果表明:非接触式眼压计的空气脉冲其流动基本满足射流理论,存在射流核心区、内外边界等特征;空气脉冲外边界角度为8.4°,不随时间变化,内边界角度从4.9°降至4.6°,随时间收窄;角膜压平时间随眼压增大而增大,而其压平直径基本不变,且压平直径为3.2~3.6mm时结果与有关文献中的非接触式眼压计压平直径数据一致。采用研制的模拟人眼配套的溯源装置对不同压平直径的情况进行实验,获得了压平直径过小将导致测量眼压偏大665Pa以上的结论,侧面验证了仿真结果的合理性。     

预制体尺度对C/C复合材料CVI增密过程影响的模拟研究

对不同直径圆柱预制体的CVI增密过程进行数值模拟研究,分析预制体尺度对增密过程及密度分布 的 影 响。针 对 高90mm,直 径 分 别 为60、120、180mm的预制体,分别模拟CVI过程中预制体的孔隙率、密度以及孔隙平均尺寸分布和变化特征。结果显示,小直径预制体经过一段时间的沉积后密度分布较为均匀,且平均密度值很高;预制体直径较大时,沉积易发生在表面区域,导致表面区域密度较高,中心区域密度值较低,影响进一步的增密过程。     

掺杂石墨烯粉末的静电纺纳米纤维薄膜的制备

基于单喷射静电纺丝法建立掺杂石墨烯粉末的聚丙烯腈(PAN)纳米纤维复合薄膜的制备方法，研究石墨烯粉末的种类、掺杂量等因素对复合薄膜微观结构的影响。结果表明：石墨烯粉末片径越小、片层数量越少、掺杂量越高，越有利于减小纳米纤维的平均直径；通过优化纺丝前驱体溶液的制备工艺，可降低石墨烯片粒径，将石墨烯的掺杂质量分数提升至7%,制备的复合薄膜的纳米纤维直径也会减少，相对于未添加石墨烯的薄膜，减小幅度达到34.0%。该制备方法利于得到纤维直径更小的PAN薄膜，降低薄膜的孔径，提高薄膜的力学性能，提升对超细颗粒物的过滤效果。     

基于OpenFOAM的含不凝气蒸汽气泡冷凝模拟

对初始蒸汽质量分数在0.5以上的干空气-蒸汽混合气泡在过冷水中的冷凝过程进行了数值研究。基于开源软件包OpenFOAM中的icoReactingMultiphaseInterFoam多相流求解器对以上问题进行模拟。采用的相界面追踪方法是流体体积方法（VOF）,并结合连续表面应力模型（CSF）,相变Lee模型以及k-ε模型建立三维数值模型。所建立的数值模型的计算结果能够较好的和实验结果匹配,表明了此模型能够很好的对含不凝结气体的蒸汽气泡直接接触冷凝的行为进行预测。结果表明：气泡体积稳定后,气泡的形状会出现震荡;在冷凝过程中,气泡的边界附近存在温度梯度;气泡的冷凝时长与过冷度和气泡初始直径呈非线性关系;终端等效直径与气泡初始直径呈线性关系,并且对于初始不凝气含量高的气泡,其终端等效直径随初始直径的增大而增长更快;小间距的竖直气泡对,下方的气泡中的蒸汽的凝结会被抑制。     

预制体尺度对C/C复合材料CVI增密过程影响的模拟研究

对不同直径圆柱预制体的CVI增密过程进行数值模拟研究,分析预制体尺度对增密过程及密度分布的影响。针对高90mm,直径分别为60、120、180mm的预制体,分别模拟CVI过程中预制体的孔隙率、密度以及孔隙平均尺寸分布和变化特征。结果显示,小直径预制体经过一段时间的沉积后密度分布较为均匀,且平均密度值很高;预制体直径较大时,沉积易发生在表面区域,导致表面区域密度较高,中心区域密度值较低,影响进一步的增密过程。     

无线螺旋内窥镜运行的肠道模型研究

无线内窥镜能够在人体胃肠道内运行,根据动压效应原理,它会在其周围自动形成动压润滑粘液膜,使内窥镜在运行时不与内腔壁发生接触,避免对人体有机组织的损伤.根据人体消化道黏液为具有剪切稀化性的非牛顿流体的实验结论,利用非牛顿流体的Reynolds方程和有限元仿真软件,得到无线螺旋内窥镜在运行时的小肠的等效应力场分布图,说明了无线螺旋内窥镜在肠道内运行的可行性.     

胶囊照相机投入使用

目前 ,一种与普通消炎药胶囊相似的照相机在广州中山大学附属第一医院临床应用 ,为多名患者诊明病情。据了解 ,在特殊的胶囊里装着小型照相机、闪光灯、微型电池、射频发送器和一条天线。病人只要携带一个便携式数据记录仪 ,吞下胶囊后 ,随着消化道不断蠕动 ,胶囊不断向前推进 ,消化道的情况通过照相机拍摄并详细传送出来。据悉 ,此种照相机可对直径小至 0 8mm的目标拍摄并放大影像 8倍。 8小时内能向数据记录仪传送近 6万幅图像。病人整个检查过程无需卧床 ,免除了以前常规检查时的痛苦。胶囊照相机为一次性使用胶囊照相机投入使用@中原…     

A Micro Peristaltic Pump Using an Optically Controllable Bioactuator

Peristalsis is widely seen in nature, as this pumping action is important in digestive systems for conveying sustenance to every corner of the body. In this paper, we propose a muscle-powered tubular micro pump that provides peristaltic transport. We utilized Drosophila melanogaster larvae that express channelrhodopsin-2 (ChR2) on the cell membrane of skeletal muscles to obtain light-responsive muscle tissues. The larvae were forced to contract with blue light stimulation. While changing the speed of the propagating light stimulation, we observed displacement on the surface of the contractile muscle tissues. We obtained peristaltic pumps from the larvae by dissecting them into tubular structures. The average inner diameter of the tubular structures was about 400 μm and the average outer diameter was about 750 μm. Contractions of this tubular structure could be controlled with the same blue light stimulation. To make the inner flow visible, we placed microbeads into the peristaltic pump, and thus determined that the pump could transport microbeads at a speed of 120 μm·s⁻¹.     

Design of a bi-directional illumination system for a dual view capsule endoscope

The capsule endoscope is an important tool for the intestinal examination. But the main disadvantage of the traditional capsule endoscope is the limited field of view. In order to solve this problem, the dual view capsule endoscope (DVCE) was developed. In this work, a dual view illumination system is designed for a DVCE. The dual view illumination system is divided into two sub-systems with a front view illumination lens and a back view illumination lens. The Bézier curves for the front view and back view illumination lenses are used for optimization, based on which we change the radiation pattern of the LED so that the dual view illumination design can support energy for the front view and back view simultaneously while achieving low power consumption and high efficiency. Moreover, a non-uniform illumination process is used to compensate for the problem of uniformity and relative illumination for the DVCE lens. Through this design, we can obtain a uniformity of 91% and an efficiency of 25.2% for front view illumination and uniformity of 91% and an efficiency of 23.5% for back view illumination. Finally, tolerance analysis can also be completed for mass production.     

Mathematical modeling of heat and mass transfer effects on MHD peristaltic propulsion of two-phase flow through a Darcy-Brinkman-Forchheimer porous medium

This article deals with the combined effects of heat and mass transfer on the peristaltic propulsion of two-phase fluid flow through a Darcy-Brinkman-Forchheimer porous medium with compliant walls. The Sisko fluid model together with small particles is considered in the presence of extrinsic magnetic field and chemical reaction. It is well-known that different biological fluids behave like a Newtonian or non-Newtonian fluid depending upon the shear rates. The non-Newtonian fluid models are more complicated than Newtonian fluid and difficult to express using the single constitutive relationship between stress and strain rate. These constitutive equations provide a complex mathematical formulation and become numerous challenges to find numerical and analytical solutions. Small magnetic particles are helpful to manipulate and control the two-phase flow by magnetic force. Moreover, it is also beneficial in drug targeting for the treatment of different diseases. Further, two-phase flow plays an important role to examine the muscular expansion and contraction during the propagation of various biological fluids. An appropriate approximation is considered such as long wavelength and creeping flow regime to model the governing equations. Analytical solutions are obtained using the perturbation method. Moreover, numerical computations are performed to determine the features of peristaltic pumping. The results of different rheological properties for particle and fluid phase are discussed mathematically as well as graphically for different sundry parameters. The current analysis has an extensive amount of applications in medical engineering and also significant importance of smart fluid pumping systems in various engineering processes.     

超微马达实用化技术及在医用内窥镜中的应用研究

介绍和总结了超微马达 (直径 12mm)的实用化关键技术 ,并应用超微马达研制了一种新型医用内窥镜系统。通过在目前临床应用的内窥镜前端装上一个超微马达 ,驱动一可用形状记忆合金调整角度的光学反射镜作低速 36 0°旋转 ,扩大了传统内窥镜的侧向观察视野 ,并减少了内窥镜对人体组织造成的意外损伤和给病人带来的痛苦 ,实现了内窥镜前端操作的自动化。超微马达在医用内窥镜中的应用表明了超微马达已从研究阶段步入实用化阶段     

Small diameter polyurethane-polydimethylsiloxane vascular prostheses made by a spraying,phase-inversion process

A highly porous, distensible, gel-like tubular membrane suitable for a small diameter arterial prosthesis was fabricated by combining techniques for spraying and phase-inversion of thermodynamically unstable solutions of a biocompatible polyurethane (PU)-polydimethylsiloxane (PDMS) blend (Cardiothane^TH51) over a sliding and rotating mandrel. The cylindrical membrane was characterizedin vitro for mechanical, morphological and permeability properties, and evaluatedin vivo as a 1.5 mm internal diameter prosthesis for the replacement of the rat abdominal aorta. A mature, stable luminal interface, a thin internal capsule without anastomotic hyperplasia, and the deposition of collagen within the voids of the polymer mesh were observed after 8 weeks of implantation.     

Influence of process variables and formulation composition on sphericity and diameter of Ca-alginate-chitosan liquid core capsule prepared by extrusion dripping method

ABSTRACT

The influence of process variables and formulation composition on the sphericity and diameter of the alginate capsules which contained dual cations (Ca-and-chitosan) are characterized in this study. Capsule sphericty was not influenced by needle diameter but instead, capsule diameter increased proportionally with the needle diameter. The combined effects of the liquid core solution and alginate solution on the sphericity of the capsules are tabulated. Spherical capsules can be produced when the following criteria were fulfilled: stirring speed is in the range of 240–300 rpm; calcium chloride concentration is >5 g/L; viscosity of liquid core solution is >203 mPa.s; as well as viscosity of alginate solution is in between 47 and 386 mPa.s. The capsule diameter was predicted using a modified Tate’s law equation and an error analysis was conducted to evaluate the equation. The predicted diameter was well correlated with the experimental data with an average absolute deviation <3.6%.     

Plasticizer effect and comparative evaluation of cellulose acetate and ethylcellulose-HPMC combination coatings as semipermeable membranes for oral osmotic pumps of naproxen sodium

The objective of this study was to compare the performance of cellulose acetate (CA) and ethylcellulose (EC)-HPMC combination coatings as semipermeable membranes (SPMs) for osmotic pump tablets (OPTs) of naproxen sodium (NPS) so as to deliver a constant, predetermined amount of drug in solution form over a fixed span of time, independent of external environmental conditions. Osmotic pump tablets were designed with different coating variables and optimized in terms of nature of plasticizer, membrane thickness, and orifice diameter. The effect of insertion of an inner microporous film around the NPS core to minimize deformation of the SPM due to peristaltic movement of the gut was also studied. Osmotic pump tablets composed of membranes with water-soluble plasticizer, propyleneglycol (PG), released drug mainly through diffusion, whereas those designed with CA and EC-HPMC (4:1) coats containing water-insoluble plasticizer, castor oil, released their contents by perfect zero-order kinetics over a prolonged period of time, though the average release rate that could be achieved with the EC-HPMC (4:1) membrane was only about half the rate achieved with the CA membrane for the same membrane thickness. Release rates for both the membranes decreased with increasing membrane thickness and were found to be independent of orifice diameter, agitation intensity, and pH of the dissolution medium.     

小直径棒材爬波检测新技术及相关理论探讨

小直径棒材的检测一直是比较棘手的问题，本文介绍一种适于此类棒材料检测的新技术－－单探头爬波水浸聚集法，并对相关理论问题进行了回顾和探讨。     

Advanced Subcompartmentalized Microreactors: Polymer Hydrogel Carriers Encapsulating Polymer Capsules and Liposomes

The design of compartmentalized carriers for advanced drug delivery systems or artificial cells and organelles is of interest for biomedical applications. Herein, a polymer carrier microreactor that contains two different classes of subcompartments, multilayered polymer capsules and liposomes, is presented. 50 nm‐diameter liposomes and 300 nm‐diameter polymer capsules are encapsulated into a larger polymer carrier capsule, demonstrating control over the spatial positioning of the subcompartments, which are either ‘membrane‐associated’ or 'free‐floating’ in the aqueous interior. Selective and spatially dependent degradation of the 300 nm‐diameter subcompartments (without destroying the structural integrity of the enzyme‐loaded liposomes) is also shown, by performing an encapsulated enzymatic reaction using the liposomal subcompartments. These findings cover several important aspects toward the development of engineered compartmentalized carrier vessels for the creation of artificial cell mimics or advanced therapeutic delivery systems.