Rapid-Fabricated and Recoverable Dual-Network Hydrogel with Inherently Anti-Bacterial Abilities for Potential Adhesive Dressings

To satisfy the ever-accelerated demands for advanced engineering biomaterials with excellent physicochemical properties, injectable and recoverable dual-network (DN) hydrogels based on poly(l -lysine)-graft-4-hydroxyphenylacetic acid (PLL-g-HPA) and Aga are constructed by simply mixing PLL-g-HPA/HRP and PLL-g-HPA/H₂O₂ in Aga through enzyme-catalyzed cross-linkage of PLL-g-HPA and temperature-adjusted sol-gel transition of Aga. The recoverable and injectable performances of hydrogels are attributed to the reversible sol-gel transitional feature of Aga and enzymatically cross-linked reaction of PLL-g-HPA. DN hydrogels have fast and adjusted gelation time, connective pore structure, superior formability, and good biocompatibility. The helically structural Aga network endows the hydrogels with good mechanical strength and superior stability in extreme condition. Schiff-base effect between amino in skin tissues and carbonyl formed by the oxidation of phenol groups in hydrogel imparts the hydrogels to promising tissue attachment. Bursting pressure assay illustrates that the bursting pressure (34.5 ± 2.4 kPa) for 13.6% DN hydrogel is much higher than arterial blood pressure (16 kPa). The incorporated cationic PLL-g-HPA gives the hydrogels remarkable antibacterial ability, which effectively prevents the bacterial infection. In conclusion, the DN hydrogel with good cytocompatibility, inherently antibacterial ability, tissue adhesion, and excellent stability in extreme environment is probably able to become a promising candidate as potential wound dressings.     

费伽罗TGS－813型气敏器件的特性研讨

ＴＧＳ－８ｌ３型可燃性气体敏感器件是日本费伽罗（ＦＩＧＡＲＯ）公司生产的，对以烷类气体为主的多种可燃性气体有良好敏感特性的广谱型敏感器件。该器件灵敏度适中，响应与恢复特性好，初期恢复特性快，长期工作稳定性、重现性、抗环境气氛影响及抗温湿度影响等性能均优，系高质量、高可靠性的气敏器件，广泛地应用于各种报警装置。本文将从实际应用出发，对其特性进行研讨。     

Fault recoverability analysis of switched nonlinear systems

The recoverability reflects the capability of the system to tolerate the worst faults over a prescribed set under admissible energy constraints. In this paper, we present the minimum amount of control energy required to drive the initial state of a nonlinear system to the origin under certain assumptions, and we also give the corresponding optimal control law. This result is then extended to switched nonlinear systems under given switching signals. On this basis, a novel fault recoverability evaluation scheme is proposed for switched nonlinear systems with respect to the given limit of energy cost. Simulation results verify the effectiveness of the proposed method.     

一个叛逆者追踪方案分析和改进

最近,王青龙等人提出了一种新的基于双线性映射的公钥叛逆者追踪方案,并称该方案具有完全抗共谋性、完全撤销性、完全恢复性和黑盒追踪性等优点.分析了王青龙等人的方案,指出该方案不能实现完全撤销功能,并对王青龙等人的方案进行了改进,提出了一个新的基于双线性映射的叛逆者追踪方案.为了减少存储、计算和通信开销,提出的方案使用多项式和过滤函数构建追踪方案.当发现叛逆者时,提出的方案能够在不更新合法用户密钥的前提下,同时安全撤销多个叛逆者,实现了完全撤销,克服了王青龙等人方案的缺陷.方案的安全性基于离散对数问题和判定Diffie-Hellma问题为困难问题.安全性证明和性能分析表明提出的方案是安全的,能满足完全抗共谋性、完全可恢复性、黑盒追踪性和完会撤销性.同时,就存储、计算和通信开销而言,提出的方案比王青龙等人的方案低.     

对于高煤阶煤层气资源科学开发的思考

我国煤层气产业已经历10多年的发展,逐步建成了沁水盆地和鄂尔多斯盆地两个产业基地,但平均单井产气量低仍然是制约中国煤层气高效开发的最大难题。目前高煤阶煤层气产量已占到我国煤层气总产量的90%以上,而高煤阶煤层气资源今后将大比例转入中深层开采,面对不同的构造场、应力场、裂隙场等复杂的煤层气赋存流动条件,现有的工程技术手段与地质适配性都面临着的巨大挑战。为此,以中国石油华北油田公司沁水盆地高煤阶煤层气技术攻关与实践为范例,剖析煤层气"四低"(储量有效动用率低、剩余可动用储量低、单井产气量低、开发利润低)开发现象,辩证思考煤层气开发的本质。研究结果表明:①对于煤层气储量可采性、地质差异性、工程技术适应性、科学排采方面的认识不到位是目前煤层气开发存在的重大问题;②必须破解现有技术条件下开发储量的控制技术、经济产能建设的区域优选技术、适应地层特征的工程技术、开发方案的顶层设计技术等关键瓶颈,此为实现煤层气科学开发的必经之路;③打破传统地质认识,突破以往认为埋深800 m以深的煤层气不宜开发的思想限制,高煤阶的马必东地区、中煤阶的大城凸起的煤层气开发实践成效已经证实:埋深既不是决定煤层气是否能够开发的界限条件,中深层也不是煤层气开发的禁区。     

靖边气田低效储量评价与可动用性分析

靖边气田是风化壳型碳酸盐岩气藏,目前处于开发中期,保持气田稳产是靖边气田面临的核心问题,而低效储量是靖边气田储量接替的重要领域。在低效储量分布特征的基础上,将靖边气田低效储量分布分为3种类型：低效储量与优质储量垂向叠加型;低效储量与优质储量侧向连通型;低效储量孤立分布型。研究结果表明,孤立型低效储量规模小,垂向叠加型和侧向连通型低效储量是靖边气田储量接替的重要类型。针对垂向叠加型和侧向连通型低效储量分布特征,采用数值模拟方法对低效储量可动用性进行分析和评价。研究结果表明,低效储层渗透率、低效储层布井方式（井距)、低效储层气井配产是影响低效储量动用程度的最主要因素。     

Transaction recovery in federated autonomous databases

Transaction management for federated database systems (FDBSs), where each participating DBMS is autonomous, supports global transactions that can access more than one database. A number of concurrency control algorithms exist for the failure-free environment. Handling transaction failure, due to concurrency control or site related reasons, becomes especially difficult in the presence of autonomy. Due to local autonomy, carrying out 2-phase commit may not be possible. This can be simulated by providing a server on top of the pre-existing DBMS at each site, which is responsible for submitting the local operations to the associated DBMS and communicating with the transaction's originating site. In this paper we formalize the problem of ensuring transaction consistency in an FDBS environment in the presence of failure. The key problem is that due to autonomy, the local DBMS and FDBS may have different views of an execution sequence generated at a site.Local recoverability is identified as the property of local execution sequences necessary for correctness. The other main problem is of guaranteeing that the various locally recoverable histories are consistent with each other. These identified properties are necessary and sufficient conditions for the correctness of FDBS recovery algorithms, and can be used to evaluate the correctness of the proposed algorithms. This paper also presents an FDBS recovery algorithm that has been proved to be correct. Formal proofs of all properties and a comparison of different algorithms are provided. Recommended by: Y. BreitbartThis work was supported in part by sub-contract #B09530013 from Honeywell SSDC, under contract #F30602-91-C-0128 from Rome Laboratory of the US Air Force.On leave from Computer Science Department, Heilongjiang University, People's Republic of China.