可吸收止血材料现状及效果评价的研究进展

可吸收止血材料是当前外科领域研究的热点,在临床以及战争中应用广泛。其种类繁多,成分复杂,尽管目前国内并没有一个完善的产品国家标准和上市指导原则,但是可以从止血效果、降解吸收性、生物相容性,以及抗菌促愈合等几个方面对其有效性进行评价。主要对可吸收材料现状及其评价工作的进展进行综述,同时探讨其在评价过程中存在的问题。     

生物可降解锌基金属材料研究进展

随着人们医疗观念的转变和材料科学的进步,医用金属植入材料的选择从传统316L不锈钢、钴铬合金、钛合金等惰性金属逐渐转向可降解材料。为了减轻与耐腐蚀支架相关的副作用(即慢性炎症和晚期血栓形成),目前正在开发新一代的生物可吸收支架,支架在完成任务后会被逐渐降解和吸收。目前的可降解金属主要包括镁合金、铁合金和锌合金,铁在动脉中产生大量的氧化产物而镁及其合金又腐蚀得太快。其中,锌合金具有更适宜的降解速度、良好的降解行为和较好的力学性能,基于锌的生物可吸收材料是近年兴起的最具发展潜力的可降解医用金属材料。本文主要介绍了纯锌、锌铜系、锌镁系及其他锌基合金近年来的主要研究进展。     

液相色谱法分析茶叶中水溶性成分

建立了茶叶中八种儿茶素和三种生物碱的液相色谱分析方法。优化了样品前处理的方法并对分析方法进行了评价。对62个茶叶样品进行了分析,发现随着发酵程度的增加,表儿茶素类化合物的含量降低;酯型儿茶素GCG存在降解现象,使得降解产物GC在乌龙茶中含量最高。     

高分子可降解生物材料的降解研究进展

高分子可降解生物材料广泛应用于生物医学领域,其降解行为对于调控材料的降解速率、分析降解产物、指导医用器件的开发与使用等具有重要意义,是当前研究的热点。综述了高分子可降解生物材料的种类、应用、降解方式及降解终点的判断方法。重点比较了各种降解方式以及降解终点判断方法的优缺点,并介绍了降解终点判断的新方法,为完善高分子可降解生物材料的降解及安全性评价标准提供参考依据。     

医用牙周组织引导再生胶原材料的特性

用酶消化法从牛腱中提取出胶原蛋白，采用涂复法制成胶原膜材料，将该膜用０．２５％的甲醛交联后得到用于牙周组织引导再生的材料．在对胶原材料进行物理、化学性能测试后表明：该材料的力学性能超过国外同类制品并具有较好的吸水性，而且胶原材料的羰基、羧基、羟基和胺基等主要结构基团依然存在经体外胶原酶和体内肌肉包埋降解吸收观察，材料在体外约２４０小时降解完全，降解产物为羟脯氨酸，体内吸收时间为６０天左右．对该材料进行生物学评价后证明：该材料无三致反应和其它毒副作用，无热原和过敏反应及溶血现象等，生物相容性优良．因此，该材料可用于牙周组织引导再生术及更广泛的生物隔膜技术中．     

聚乳酸材料的化学解聚研究进展

聚乳酸(PLA)作为一种性能优良的生物降解材料,被用于工业、包装业及医药业等领域。随着PLA的广泛使用,其生产和消耗的数量急剧增加,最终导致废旧PLA的堆积日益严重。尽管PLA能在自然条件下降解,但降解周期过长,降解产物也无法直接进行循环再利用。通过化学回收法可将PLA材料进行解聚,生成相应的小分子产物,产物经分离、纯化后可重新作为生产PLA的单体或合成其它化工产品的原料,从而实现资源的循环利用。文中综述了近年来国内外聚乳酸(PLA)材料的化学降解回收产品的研究现状,介绍了几种主要的化学解聚方法,包括热裂解、水解、醇解、酶解及光解等,并对各方法的优缺点进行了分析与总结。最后,对PLA的化学降解进行了展望。     

聚乳酸立构复合物规整度对其降解性能的影响

通过开环聚合法,利用D,L-丙交酯合成不同规整度(XD)的左旋聚乳酸PLLA和右旋聚乳酸PDLA。用溶液浇铸法制得不同规整度的聚乳酸立构复合物SC-PLA,并在50℃缓冲溶液中进行降解。通过分析剩余质量、溶液pH值、热性能(DSC)、表面形貌(SEM)、电离子喷雾质谱(ESI-MS)等评价SC-PLA的降解性能。结果表明:相同规整度时,SC-PLA降解速率小于PLLA,但pH值变化大于PLLA,立构复合物SC的存在使材料比常见PLLA更耐水解;立构规整度下降会使SC-PLA的结晶度降低,材料的降解速率加快;降解使材料的结晶度上升,立构复合物晶体SC与均聚物晶体HC熔点降低;高规整度SC-PLA相对于相同规整度PLLA及低规整度SC-PLA,其降解产物分子链长度更短。     

可降解聚乳酸/羟基磷灰石杂化材料——Ⅲ.聚乳酸/羟基磷灰石杂化材料的制备及降解

采用超声分散技术,以聚(D,L)-乳酸(PDLLA)和纳米羟基磷灰石(HA)为原料,制备出PDLLA/HA杂化材料,研究了PDLLA/HA杂化材料在生理盐水中的降解性能,并对相关产物进行了FT-IR、TEM、XRD分析。结果表明,杂化材料中PDLLA与HA间通过氢键结合,随着HA含量的增加,杂化材料在生理盐水中的降解速率减缓,此外,杂化材料的降解包括PDLLA的降解和HA的重新沉积钙化两个过程,降解12周后,HA的晶体结构被破坏,重新沉积钙化形成多孔骨骼结构。     

可降解聚乳酸/羟基磷灰石杂化材料--Ⅱ.聚乳酸/羟基磷灰石杂化材料的制备及降解

采用超声分散技术,以聚（D,L）-乳酸（PDLLA）和纳米羟基磷灰石（HA）为原料,制备出PDLLA／HA杂化材料。研究了PDLLA／HA杂化材料在生理盐水中的降解性能,并对相关产物进行了FT-IR、TEM、XRD分析．结果表明,杂化材料中PDLLA与HA间通过氢键结合,随着HA含量的增加,杂化材料在生理盐水中的降解速率减缓,此外,杂化材料的降解包括PDLLA的降解和HA的重新沉积钙化两个过程。降解12周后,HA的晶体结构被破坏,重新沉积钙化形成多孔骨骼结构。     

1,4-丁二醇降解废弃涤纶短纤

采用1,4-丁二醇降解废弃涤纶短纤,研究了其降解的工艺条件,降解温度控制在190~228℃。降解产物通过减压蒸馏提纯,蒸馏温度为220~250℃,然后用提纯后的产物制备聚氨酯泡沫,并研究了该泡沫的性能。用红外光谱分析了降解产物的结构;用差示扫描仪表征了降解产物的熔点约为203℃,聚氨酯泡沫的熔点有所升高;用热重分析仪研究了产物及聚氨酯泡沫的热性能;用万能材料试验仪测试了泡沫的压缩载荷。     

基于小动物荧光成像研究生物材料体内降解的实验方法

可降解材料作为生物材料的重要组成部分,其体内降解性能的好坏往往决定着材料植入后的成败。因此,对材料体内降解的评价显得尤为重要。传统的生物材料体内降解评价方法需要在各取样点取出不同批次的降解样品,阻止了对同一个实验样品降解过程的连续测量,并且存在样品需求量大的问题。小动物活体成像系统(in vivo imaging system,IVIS)具有非侵入性、操作性强等特点,为解决上述问题提供了思路。本研究旨在建立一种利用小动物荧光成像系统检测可降解材料降解性能的方法,通过将近红外荧光染料经化学反应标记到可降解材料上,由荧光强度的变化反应材料的降解程度。体内降解实验表明此方法制得的荧光标记材料,荧光稳定性高,材料降解过程中荧光强度变化与质量损失拟合效果良好(R2=0.9994)。综上,该方法解决了测量材料降解样品量大的问题,并且提高了实验过程的连贯性。      

纳米纤维素基材料在柔性电子器件中的应用

目的 由于纳米纤维素基材料良好的柔韧性、热力学性能和高透明度,近年来在柔性电子产品中引起越来越多的关注。通过综述该领域的研究进展,将有助于研究人员更高效地开展研究。方法 综述3类纳米纤维素的制备方法及将纳米纤维素基材料应用在柔性电子产品中的研究进展。分别阐述纳米纤维素基材料应用于器件柔性衬底及绝缘材料的研究实例,并讨论纳米纤维素在各种应用方向中的优势以及存在的问题,最后对材料的未来应用前景进行展望。结论 纳米纤维素是天然纤维素与纳米技术结合的产物,可主要划分为纤维素纳米纤丝、纤维素纳米晶以及细菌纤维素3类。近年来,纳米纤维素基材料作为电子器件柔性衬底、绝缘材料等研究均有许多成果问世。虽然纳米纤维素基电子器件的开发还主要停留在实验室阶段,但是与传统的石油化工产品相比,纳米纤维素具有原材料丰富、环保可降解等优点。对纳米纤维素基新型材料的开发利用,有助于解决人类社会中日益严重的电子垃圾问题。     

The Inverse Gaussian Process as a Degradation Model

This article systematically investigates the inverse Gaussian (IG) process as an effective degradation model. The IG process is shown to be a limiting compound Poisson process, which gives it a meaningful physical interpretation for modeling degradation of products deteriorating in random environments. Treated as the first passage process of a Wiener process, the IG process is flexible in incorporating random effects and explanatory variables that account for heterogeneities commonly observed in degradation problems. This flexibility makes the class of IG process models much more attractive compared with the Gamma process, which has been thoroughly investigated in the literature of degradation modeling. The article also discusses statistical inference for three random effects models and model selection. It concludes with a real world example to demonstrate the applicability of the IG process in degradation analysis. Supplementary materials for this article are available online.     

Materials selection and multi-attribute utility analysis

Summary Multi-attribute utility analysis (MAUA) has emerged as a powerful tool for materials selection and evaluation. An operations research technique, MAUA has been used in a wide range of engineering areas, of which materials science and engineering is one of the more recent. Utility analysis affords a rational method of materials selection which avoids many of the fundamental logical difficulties of many widely used alternative approaches. However, MAUA has traditionally been used in materials selection problems only, in which there is certainty regarding the attribute levels of the alternatives. For many new technologies this is not the case. Another operations research technique, subjective probability assessment (SPA), can be used to address this issue. SPA makes it possible to measure a probabilistic distribution describing the confidence of the decision maker in the levels of attributes for which there is a high degree of uncertainty. These probability distributions can be used in conjunction with MAUA to provide a consistent framework for making materials selection decisions. Furthermore, the use of these techniques extends beyond the problem of materials selection into the more speculative areas of materials competitiveness and market demand in cases involving new, unproven technologies.     

中国人工智能产品的设计评价现状与发展趋势研究综述

目的 针对中国的设计现状,通过探索现有产品的设计评价体系是否适切于人工智能产品,能够为人工智能产品的设计及评价研究提供一个更完整的视角。方法 以对比分析为主要研究手段。探析产品和人工智能产品的核心理念,分析两者之间的区别,为研究主体定性;针对产品和人工智能产品的设计评价展开数据计量分析,了解2个领域的研究热点与发展趋势;剖析人工智能、人工智能产品和人工智能产品设计评价的现存问题和发展演进,从历史角度梳理阶段性研究成果并展开热点评述,进一步定义人工智能产品的设计评价热点前沿与发展趋势;综合所有分析结果共同定位现有产品的设计评价体系对人工智能产品设计评价的适切度。结果 论述了人工智能产品设计评价的重要作用,梳理了现存理论与方法,定位了发展程度,预测了未来的研究重点和发展方向,为构建更加科学、客观且适切的人工智能产品的设计评价体系提供了理论依据。有助于把控生成产品的质量,提高产品应用落地率,使之与研发投入保持相互平衡的状态,同时可反向助力于优化人工智能的算法和技术。结论 综合基本逻辑的区别探析、数据计量分析和发展演进研究的结果,论证了中国现有产品的设计评价体系与人工智能产品的设计评价体系是部分适切的关系,因此人工智能产品的设计评价体系研究与构建不能完全移植产品设计评价的研究成果,需要在部分借鉴与参考现有成果的基础之上展开以人工智能产品特殊性为核心的针对性研究,进而构建成熟的人工智能产品的设计评价体系。     

Laser confocal microscopic study of pH profiles of synthetic absorbable fibers upon in vitro hydrolytic degradation

The objective of this study was to develop a new and non-destructive technique to measure the interior pH of synthetic absorbable biomaterials. Such a measurement would provide the required experimental evidence for validating the postulated theory that the accumulation of acidic hydrolytic degradation products within the interior of aliphatic polyesters is responsible for the observed accelerated degradation of this class of absorbable biomaterials. This new technique used a laser scanning confocal microscope coupled with pH sensitive fluorescent dyes like Texas Red sulfonyl chloride. The capability of optical thin sectioning of a laser confocal microscope would permit a non-destructive examination of the interior of biomaterials. Poly-p-dioxanone suture fibers (PDSII) of size 2/0 were used as the model compound for this new technique. The pH values of the unhydrolyzed and partially hydrolyzed PDSII fibers were found to decrease with increasing depth from the fiber surface and reached as low as about 3.5 at 70 microm depth. The largest depth that an interior pH could be measured within absorbable biomaterials was determined by the opacity of the biomaterials, i.e. a higher depth for a less opaque material. The observed interior pH profiles were correlated to the unique morphologic structure of PDSII fibers.     

The characterisation of two different degradable polyethylene (PE) sacks

The compostability of two different polyethylene (PE) products on the UK market under open-windrow composting conditions is explored within this paper. Chemical analysis of the PE bags has established their constituents in order to examine how the PE bags have an increased degradability depending on additives. Weight loss of the two different PE products within open-windrow composting conditions was recorded in order to establish the percentage weight loss as an indication of the degradability of the two products and their relative suitability for open-windrow composting. Scanning electron microscopy (SEM) of the PE products over the composting duration established the degradation processes for the PE products within the compost. These analyses concluded that one of the PE product mixes was more degradable than the other. However, neither product completed degraded within the timeframe of 12–14 weeks generally accepted for open-windrow composting in the UK.     

Understanding the Insight Mechanism of Chemical-Mechanical Degradation of Layered Co-Free Ni-Rich Cathode Materials: A Review

Layered Cobalt (Co)-free Nickel (Ni)-rich cathode materials have attracted much attention due to their high energy density and low cost. Still, their further development is hampered by material instability caused by the chemical/mechanical degradation of the material. Although there are numerous doping and modification approaches to improve the stability of layered cathode materials, these approaches are still in the laboratory stage and require further research before commercial application. To fully exploit the potential of layered cathode materials, a more comprehensive theoretical understanding of the underlying issues is necessary, along with active exploration of previously unrevealed mechanisms. This paper presents the phase transition mechanism of Co-free Ni-rich cathode materials, the existing problems, and the state-of-the-art characterization tools employed to study the phase transition. The causes of crystal structure degradation, interfacial instability, and mechanical degradation are elaborated, from the material's crystal structure to its phase transition and atomic orbital splitting. By organizing and summarizing these mechanisms, this paper aims to establish connections among common research problems and to identify future research priorities, thereby facilitating the rapid development of Co-free Ni-rich materials.     

双酚A缩水甘油醚/乙二胺环氧树脂的热分解行为

采用傅里叶红外光谱法研究了双酚A缩水甘油醚/乙二胺环氧树脂(DGEBA/EDA)在不同温度时分解残留物的红外吸收光谱;利用热分析技术考察了DGEBA/EDA从室温到600℃之间的热解反应。结果表明,DGEBA/EDA环氧树脂在氮气中分解时存在一个热解阶段,最低热解活化能为195.74 kJ/mol。色谱-质谱联用(GC/MS)分析DGEBA/EDA环氧树脂热解残留物,表明在热解过程中主要生成苯酚、对异丙基苯酚和双酚A。讨论了DGEBA/EDA环氧树脂热解的机理。经热解后的残留环氧树脂的热稳定性降低明显,环氧树脂发生了明显的化学裂解。     

A Simple Method for Estimation of Residual Stresses by Depth‐Sensing Indentation

Abstract: The evaluation of residual stresses is an important aspect in many engineering applications, such as surfaces produced by mechanical or thermal treatment processes or even thin films deposited on substrates. Currently, there are several techniques for residual stress measurement. However, its application is limited by problems associated with the precision and simplicity of measurement, as well as their applicability to a wide variety of materials and situations. Indentation tests are widely used in determining the mechanical properties of materials, so it is very important to assess their sensitivity to the presence of residual stresses. In this context, recourse to numerical simulation of indentation testing proves to be an important tool to study the effect of residual stresses in the determination of hardness and modulus as well as the actual determination of residual stresses. This paper investigates the influence of the presence of equibiaxial residual stresses in the indentation test results. It proposes a methodology for reverse analysis to determine the sign and value of the equibiaxial residual stresses present in the surface of materials, from depth‐sensing indentation results. For applying this methodology, the elastic and plastic behaviour of the material must be previously determined.