防止帘布筒产生气泡的一段上压辊

介绍了一种全钢工程子午线轮胎三段成型机上的一段上压辊装置,此压辊长约3 m,直径160 mm,安置在一段胎体鼓的上方,贴合帘布时,此压辊由气缸推动压在鼓面与帘布的切点处。此压辊由295片压片套在一根开槽空心方轴上,开槽空心方轴内部有充气的胶管,充气胶管为295片压片提供压力,且每片压片都能单独在设定压力下通过切点沿直径方向给力,使帘布沿鼓面切线方向贴合时紧贴鼓面（或前序贴完的帘布）,防止帘布往鼓面上贴合时产生气泡,造成轮胎产生质量问题。     

基于熔融纺丝PAN原丝的数值模拟研究

采用熔融纺丝制备聚丙烯腈(PAN)基碳纤维原丝,根据聚合物熔融纺丝的基本原理,选取PhanThien-Tanner微分粘弹模型,利用Polyflow软件对PAN熔融纺丝过程进行数值模拟,研究了PAN原丝制备过程的直径变化、拉伸速率分布、温度分布规律。结果表明:在距喷丝板0~10 cm处纤维直径急剧缩小,10~20 cm处开始缓慢减小,之后趋于稳定,纤维表面和纤维中心拉伸速率几乎重合,纤维中心温度一直高于表面温度,在离喷丝板2~15 cm处,纤维中心温度与表面温度之差较大,之后温差变小最终趋于0℃;数值仿真模拟可以较准确地模拟PAN熔融纺丝过程;熔融纺丝制得PAN原丝,其断裂强度能满足高性能碳纤维原丝的强度要求。     

平片无张力疝修补术在腹外疝的应用体会

目的总结平片式无张力修补术在腹股沟及切口疝的应用效果。方法采用意大利Herniamesh公司的聚丙烯平片修复腹股沟疝65例,切口疝12例,对结果进行总结。结果77例手术过程顺利,手术时间平均50min。皮下积液2例,3例为切口疝,阴囊积液3例,感染1例,换药6个月后治愈,未取出补片。无尿潴留,6～12h内下床活动,随访3～24个月无复发及不适感。结论平片式无张力疝修补术,操作简单、恢复快、费用低是腹外疝的理想疝修补术。     

含DG配电网故障定位的免疫二进制萤火虫算法

为能准确、快速定位含分布式多电源的配电网故障区段,研究含分布式电源配电网故障区段定位的免疫二进制萤火虫算法.先在算法中融入记忆池和免疫算法思想;然后建立故障区段定位函数,定位出配电网故障区段.试验表明,算法能准确定位出配电网中的单点与多点故障,证明了算法在收敛性与容错性上都有良好的表现.     

食管胃前壁单层吻合预防食管癌术后吻合口狭窄167例临床分析

目的探讨食管胃前壁单层吻合预防食管癌术后吻合口狭窄的价值。方法常规经二切口或三切口行食管癌根治性切除,区域淋巴结清扫后,将胃经食管床上提至颈部,于胃底作一长约3～4cm切口(略大于食管切缘),分别距食管断缘及胃底切口缘约1cm处行食管后壁肌层和胃后壁浆肌层固定3针,然后行食管后壁断缘和胃底切口后壁缘间断全层吻合,针距约0.3～0.5cm,边距(针距切缘)约为0.5cm。再用褥氏内翻吻合食管前壁断缘和胃底切口前壁缘。边距(针距切缘)约为0.5cm,褥氏内针距为0.5～1.0cm,褥氏外针距为0.3～0.5cm。食管胃前壁不做包埋加固。为防吻合口掉入胸腔,可将胃前壁固定2针于颈前肌群上。最后常规放置引流管后,缝闭颈部切口及关胸,关腹。结果本组167例,无手术死亡,吻合口瘘发生率1.8%(3/167),经保守治疗愈;无吻合口出血,术后开始进食时间与传统吻合方式相比无差别。术后3个月随访吻合口狭窄发生率3.0%(5/167);经扩张治疗后均能进软食,术后6个月167例随访均能进软食,有胸骨后烧灼感或返酸等返流症状者11例(发生率6.6%)。结论该方法有效降低了吻合口狭窄发生率,而且简化了手术操作步骤,未增加其他并发症的发生率。     

全钢载重子午线轮胎成型工艺对轮胎径向力波动的影响

试验研究全钢载重子午线轮胎成型工艺对轮胎径向力波动(RFV)的影响。结果表明,采取胎面接头位于胎面传递环上方、成型半部件接头定位角度均匀分布、胎面正常长度减小10 mm、胎面传递环瓦块尺寸与胎坯直径差异较小、在确保能夹紧胎面复合件的情况下降低胎面传递环瓦块夹持压力等措施,有利于减小轮胎RFV,提高轮胎均匀性。     

LNG绕管式换热器壳侧降膜沸腾数值模拟研究

使用ANSYS Fluent商用软件下的VOF模型,对天然气液化工艺中所用的绕管式换热器壳侧降膜沸腾过程进行了数值模拟。结果表明,当壳侧入口干度x ≤ 0.10时,VOF模型能较好地模拟壳侧沸腾换热现象,准确地预测出沸腾换热系数与冷剂质量流率间的关系。降膜流状态下,汽、液相流速较低,摩擦压降较小,换热管壁面基本被液膜覆盖,液相冷剂在受热壁面汽化后进入壳侧流道,流道内以汽相为主。壳侧既有竖直向下的主流运动,又有较为微弱的螺旋环流,同时大量的汽相将在壳侧顶部涡旋滞留。     

光纤测量粒子直径的方法研究

介绍一种用光纤测量大量粒子直径的分布的方法。通过在光纤探头内的若干根光纤传输光束直接发射到被测粒子上,由设置在光纤探头内的接收装置把接收到的粒子遮挡光信号传送到光电元件;经处理,由计算机采集,然后计算出粒子运动速度、方向、直径及分布。它能精确、快速地测量大于20μm 液滴或球形粒子运动速度、方向、直径及分布。     

编读往来

分享拍摄经验,交流创作心得,专业技巧问答,读者意见回馈。名家评刊：带你走上职业摄影师的道路!柴继军：一年前,开始关注《影像视觉》杂志,这本杂志给我的第一印象是不太像国内传统的摄影杂志。随着不断地阅读,这种印象逐渐清晰立体起来。首先,《影像视觉》的定位相当准确,尤其在读者受众定位上。我能清晰地感觉到它的     

酸化交联体系助剂的优化分析

酸化压裂是指将地层压开,然后挤入地层的酸液沿裂缝流动,酸液对裂缝壁面的岩石进行化学溶蚀,达到改善储集层物性,最终使油井增产.但是在压裂过程中需要不同功能的添加剂,本文对酸液所需的缓蚀剂、铁离子稳定剂和助排剂进行了优选,结果显示,当缓蚀剂为WDEH,加量为3.0％时,酸液对N80钢片的腐蚀速率最低,仅为2.54 g/m2...     

Design and in vivo assessment of polyester copolymers based on trimethylene carbonate and ε‐caprolactone

Poly(trimethylene carbonate‐co‐caprolactone) (PTCL) copolymers with various trimethylene carbonate ratios were synthesized by ring‐opening polymerization and were used to prepare implants for an in vivo experiment. Medical silicone rubber was used as the control. Implants were prepared by compression molding with a laboratory instrument. The properties of these copolymer implants were investigated. PTCL implants and silicone rubbers were implanted subcutaneously in the dorsal region of New Zealand white rabbits. The assessment was performed 1, 2, 3, 4, 5, 6, 7, and 8 months postoperatively by the determination of the weight loss, water uptake, thermal behavior, molecular weight of the explanted implants, and histological examination. During the 8‐month implantation, the value of maximum weight loss was found to be 25%. A continuous decrease in the molecular weight occurred. No remarkable tissue reactions were observed during degradation, and foreign‐body reactions were similar to those of silicone rubbers, which are commercially available materials. In this study, we aimed to indicate the likely clinical behavior but good biodegradable properties of PTCL copolymers compared to those of silicone rubber. This may open a new avenue of application for them in the drug industry. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41815.     

Endurance of gel‐filled silicone breast implants as a function of maximum load in cyclic compression tests

The mechanical behaviour of gel‐filled silicone breast implants is examined under compressive load. First the implants are tested by applying various loads in a repetitive fashion until shell rupture occurs. Subsequently the results are presented allowing an assessment of the correlation between the number of loading cycles and the maximum compressive load. Finally it is possible to estimate the endurance of the silicone breast implants. Using a power law, a correlation between endurance and maximum load is revealed. © 2018 Society of Chemical Industry     

Chemotactic tube-foot responses of a spongivorous sea starPerknaster fuscus to organic extracts from antarctic sponges

Hexane, chloroform, and methanol extracts of 18 species of antarctic sponges were tested for their ability to induce sustained tube-foot retraction in the antarctic spongivorous sea starPerknaster fuscus. Extracts were imbedded in silicone and used to coat the tip of a glass rod, which was allowed to contact an extended tube-foot. Retraction times were measured and compared with three controls: contact with a glass rod coated with a hexane extract of fish (feeding stimulant), contact with the glass rod alone (mechanical control), and contact with the glass rod coated with silicone alone (silicone control). Only extracts of the spongeMycale acerata did not elicit significantly longer tube-foot retraction times than controls for at least one of the three organic extracts. Hexane sponge extracts elicited the lowest levels of significant tube-foot responses, with only 39% of the sponge species tested showing activity in this fraction. In contrast, chloroform and methanol extracts elicited a significant tube-foot retraction response in 73% and 78% of the species tested, respectively. This indicates that in this assay repellent metabolites are generally more polar substances. It remains to be determined that secondary metabolites are responsible for all of the tube-foot retraction responses detected in sea stars exposed to sponge extracts; bioactive secondary metabolites have been isolated from a number of these antarctic sponges. It may be of ecological significance that the two rapidly growing sponges,Homaxinella balfourensis andMycale acerata, were either not repellent or had low repellency, and thatM. acerata is the primary dietary item ofPerknaster fuscus.     

Hydrophilisation of silicone rubber for medical applications

Silicone rubber is one of the biomaterials used for preparation of medical implants. The properties of silicone rubber and methods of their evaluation are surveyed with respect to the medical applications. For some applications the hydrophobic character of silicone rubber is undesirable and possibilities of its hydrophilisation are presented in this review as well. Special attention is paid to the process of preparation of hydrophilic silicone rubber–hydrogel composite materials based on acrylic and methacrylic acids derivatives and to the properties of such materials. Copyright © 2003 Society of Chemical Industry     

A study on the role of polypropylene fibers and silica nanoparticles on the compression properties of silicone rubber composites as a material of finger joint implant

In this study, different contents of SiO₂ nanoparticles and polypropylene fibers were added to silicone rubber matrix as a material of finger joint implants and mechanical properties of these composites were investigated before and after being soaked in simulated body fluid. Results of compression test revealed that compression stress of silicone rubber by addition of the 2 wt% silica and 2 wt% PP fibers increased from 0.98 to 1.9 and 2.37 MPa, respectively. These stresses decreased after being soaked in SBF and water absorption results proved this. Increasing silica contents caused an increase in water absorption while increasing PP fibers showed contrary behavior.     

Compressive and cyclic loading of silicone breast implants and their effect on shape resilience and reliability of the shell material

The mechanical behavior of gel‐filled silicone breast implants has been examined as well as the mechanical properties of the implant shell itself. For the first time the implants were tested under compression in two different ways. Subsequently the implant shell material was analyzed by tensile test on dumbbell‐shaped specimens. The results are presented in contour plots which provide a detailed view of the measured values of the samples. Finally a statistical failure analysis was carried out by means of a Weibull fit to provide further data on the mechanical behavior. © 2017 Society of Chemical Industry     

On the failure of silicone breast implants: new insights by mapping the mechanical properties of implant shells

This review summarizes the knowledge on rupture (in vivo as well as under laboratory conditions) of gel‐filled silicone breast implants, which has been an open question since the first implantation in 1962. We present recent progress which has been made by a mapping of the mechanical properties of the shell material together with a statistical failure analysis by means of a Weibull fit. Reference implants and intact as well as ruptured explants are tested after several years in vivo using tensile tests. Up to 110 dumbbell‐shaped specimens per implant are measured allowing a detailed mapping of the mechanical properties of the silicone shell. Therefore, it is possible to illustrate the results of the tensile tests by mapping the measured values of the implants in the form of a contour plot revealing novel insights. The contour plots clearly display that the mechanical behaviour (e.g. stress at break) varies significantly over the shell. Additionally, a map is proposed which clearly shows separated clusters for different manufacturers and product categories. © 2013 Society of Chemical Industry     

医用级硅橡胶残存单体及低聚物的测定

选择Ｓｉ－Ｃ伸展振动和ＣＨ３平面摇摆震动在～８５５ｃｍ－１及～８００ｃｍ－１处的吸收峰作为分析峰,采用红外光谱分析法对ＳＹＺ—２医用级硅橡胶残存单体及低聚物含量作了测定,未检出残存单体及低聚物。     

Polymer-Encapsulated Phosphor Particles for In Vivo Phosphor Luminescence Applications

Phosphor thermometry is a highly sensitive, rapid, and portable thermal sensing technique that offers advantages over traditional contact-based thermometry techniques. Phosphor particles would however require an encapsulation medium that is biocompatible and yet optically transparent to permit optical access to the embedded phosphor particles. Here, phosphor-doped silicone implants with varying concentrations were prepared and tested in a rat model. Results indicate that such phosphor-doped polymeric implants are stable, produce a detectable signal, and demonstrate the feasibility of phosphor thermometry as a noninvasive remote thermal sensing technique for in vivo applications. Also, encapsulation in silicone did not lead to significant attenuation of the incoming signal.     

Physical,mechanical, and biocompatibility evaluation of three different types of silicone rubber

Silicone rubber as a valuable biomaterial is widely used in medical applications, but its surface properties and low wettability make serious problems in long‐term implants. This work was undertaken to evaluate the biocompatibility of modified silicone rubber using two different techniques. A blend of poly(acrylamide) and silicone rubber was compared with virgin silicone surfaces as well as with those modified by laser treatment. Physical and mechanical properties of the samples were examined using different techniques. The hydrophilicity of the silicone rubber increased with increasing hydrogel content and decreased as a result of laser treatment. Both fibroblast cell (L929) and platelet behavior in contact with these surfaces were evaluated in vitro. The morphology of fibroblast cells that adhered to the blends was similar to the control. In contrast, on the laser‐treated surfaces fibroblast cells showed different proliferation. On the other hand, fewer platelets adhered to the laser‐treated surface than adhered to the blend and the unmodified PDMS surfaces. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2522–2529, 2003