Construction of coordination networks with high connectivity: a new 8-connected self-penetrating network based on tetranuclear metal clusters

Two highly connected cobalt(II) and zinc(II) coordination polymers with tetranuclear metal clusters as the nodes of network have been prepared, being the first example of an 8-connected self-penetrating net based on a cross-linked alpha-Po subnet.

群组通信环境中的密钥管理协议

随着群组通信业务的普及，群组通信的相关安全研究也随之兴起。群组密码学的概念首先由 Desmedt 提出。与传统通信中的密码学方案相比，群组密码学具有很多优点，并已经成功地运用到视频点播和分布式系统等一些应用场景中。群签名，环签名，广播加密等密码学体制作为群组密码学的重要分支都得到了学术界的密切关注。本文的研究工作集中在群组密码学的一个重要组成部分：群组密钥管理，即多个（群组）用户在不安全的开放网络环境中通过一定的协议产生一个共享的会话密钥，为后面的通信提供各种安全性保护。 本文的研究工作主要包含两个方面，群组密钥分发协议和可证明安全的认证群组密钥协商协议。在对已有的群组密钥管理方案进行了大量的调查与分析后，我们在此基础上提出了一些有价值的研究成果。本文的主要成果包括： 1. 在第二章中，提出了一种高效的长期 self-healing 群组密钥分发方案。和已有方案相比，新方案的优势包括：（1）我们避免了使用指数运算, 而只是域上多项式的相关运算；（2）群组管理者广播消息次数比 Staddon 等人和Blundo 等人的方案少一次；（3）用户端存储私钥数目比 Staddon 等人的方案少将近一半；（4）新协议的安全性为无条件安全。 2. 在第三章中，构造了一个从一般群组密钥协商协议向基于口令认证的群组密钥协商协议转换的编译器。编译器的构造利用了对称加密体制，NM-CCA2 和 IK-CCA2 安全的公钥加密体制，以及 UF-CMA 安全的数字签名体制，从而使得编译器可以避免在线/离线字典攻击。 3. 在第四章中，提出了一个基于口令认证的群组密钥协商协议，使得网关在认证服务器的协助下和多个用户之间建立一个会话密钥，同时认证服务器不知道此会话密钥的任何信息（网关和认证服务器之间的信道是专用信道）。由于意识到口令的泄露往往是由于用户的不当使用造成的，所以，不同于已有的基于口令认证的门限密钥协商机制，我们的门限方案是在用户端实施。我们的门限方案要求把用户群组和认证服务器预先共享的口令（称之为群组口令）以秘密共享方式分散共享在群组用户之间，并且每个用户所存储口令的子秘密（share）值依然是一个易记忆的口令（称之为用户口令）。只有不少于 k 个用户一起才能恢复出群组口令。 4. 在第五章中，利用了Unified 模型（把用户长期私钥嵌入到密钥协商过程）构造了一个在 Strong Corruption 模型下可证明安全的强健的认证群组密钥协商协议。和已有类似方案相比，新方案所需要的签名数量明显减少，从而，计算复杂度和通信复杂度也随之降低。另外，新协议是在 Strong Corruption 模型下可证明安全，在此模型下的类似协议比较少。 5. 在第六章中，对 Desmedt 等人提出的 BD-II（树型）群组密钥协商协议做出改进。利用在树中各个节点上应用遮罩函数，我们把由于群组关系变化而对密钥更新所产生的影响限制在一个比较小的群组范围中，从而提高了协议在动态情况下运行的效率。新协议通过四个子算法：初始化，成员加入，成员撤销，子群组合并来分别应对群组密钥协商过程中所遇到的各种（动态）情况。

Constructing Thin Polythiophene Film Composed of Aligned Lamellae via Controlled Solvent Vapor Treatment

Thin poly(3-butylthiophene) (P3BT) film composed of aligned lamellae attached to the edge of the original film has been achieved via a controlled solvent vapor treatment (C-SVT) method. The polarized optical microscopy operated at both single-polarization and cross-polarization modes has been used to investigate the alignment of the fiber-like lamellae. A numerical simulation method is used to quantitatively calculate angle distributions of the lamellae deviated from the film growth direction. Prepatterned P3BT film edge acts as nuclei which densely initialize subsequent crystal growth by exhausting the materials transported from the partially dissolved film. The growth of new film upon crystallization is actually a self-healing process where the two-dimensional geometric confinement is mainly responsible for this parallel alignment of P3BT crystals. The solvent vapor pressure should be carefully chosen so as to induce crystal growth but avoid liquid instability which will destroy the continuity of the film.

A one-dimensional network from the self-assembly of gold nanoparticles by a necklace-like polyelectrolyte template mediated by metallic ion coordination

A new approach to one-dimensional organization of gold nanoparticles (2-4 nm) is described, using poly(4-vinylpyridine) (P4VP) molecular chain as a template with the mediation of free Cu2+ ion coordination. The assembly was conducted on freshly prepared mica surfaces and in aqueous solution, respectively. The surface assembly was characterized by tapping mode atomic force microscopy (AFM), observing the physisorbed molecules in their chain-like conformation with an average height of 0.4 nm.

A method to construct a third-generation horseradish peroxidase biosensor: Self-assembling gold nanoparticles to three-dimensional sol-gel network

A novel method for fabrication of horseradish peroxidase biosensor has been developed by self-assembling gold nanoparticles to a thiol-containing sol-gel network. A cleaned gold electrode was first immersed in a hydrolyzed (3-mercaptopropyl)-trimethoxysilane (MPS) sol-gel solution to assemble three-dimensional silica gel, and then gold nanoparticles were chemisorbed onto the thiol groups of the sol-gel network. Finally, horseradish peroxidase (HRP) was adsorbed onto the surface of the gold nanoparticles. The distribution of gold nanoparticles and HRP was examined by atomic force microscopy (AFM). The immobilized horseradish peroxidase exhibited direct electrochemical behavior toward the reduction of hydrogen peroxide. The performance and factors influencing the performance of the resulting biosensor were studied in detail. The resulting biosensor exhibited fast amperometric response (2.5 s) to H2O2. The detection limit of the biosensor was 2.0 mumol L-1, and the linear range was from 5.0 mumol L-1 to 10.0 mmol L-1. Moreover, the studied biosensor exhibited high sensitivity, good reproducibility, and long-term stability.

Self-organization of interlaced network lamellar crystals of trans-1,4-polybutadiene (TPBD) on an amorphous surface

A novel morphology of TPBD crystals consisting of a three-dimensional interlaced network was obtained by casting the self-seeded 0.1% benzene solution onto carbon-boated mica. Both the transmission electron microscopy (TEM) and electron diffraction (ED) analyses showed that the network was composed of well-developed lamellae. It is imagined this interesting morphology is the results of asymmetrical growth of the original TPBD lamellae on the amorphous interface, and that their preferred orientation changed when they encountered each other.

Fluid flow induced calcium response in bone cell network

In our previous work, bone cell networks with controlled spacing and functional intercellular gap junctions had been successfully established by using microcontact printing and self assembled monolayers technologies [Guo, X. E., E. Takai, X. Jiang, Q. Xu, G. M. Whitesides, J. T. Yardley, C. T. Hung, E. M. Chow, T. Hantschel, and K. D. Costa. Mol. Cell. Biomech. 3:95-107, 2006]. The present study investigated the calcium response and the underlying signaling pathways in patterned bone cell networks exposed to a steady fluid flow. The glass slides with cell networks were separated into eight groups for treatment with specific pharmacological agents that inhibit pathways significant in bone cell calcium signaling. The calcium transients of the network were recorded and quantitatively evaluated with a set of network parameters. The results showed that 18 alpha-GA (gap junction blocker), suramin (ATP inhibitor), and thapsigargin (depleting intracellular calcium stores) significantly reduced the occurrence of multiple calcium peaks, which were visually obvious in the untreated group. The number of responsive peaks also decreased slightly yet significantly when either the COX-2/PGE(2) or the NOS/nitric oxide pathway was disrupted. Different from all other groups, cells treated with 18 alpha-GA maintained a high concentration of intracellular calcium following the first peak. In the absence of calcium in the culture medium, the intracellular calcium concentration decreased slowly with fluid flow without any calcium transients observed. These findings have identified important factors in the flow mediated calcium signaling of bone cells within a patterned network.

Optical interconnection for neural networks by use of a self-imaging function

A grating-lens combination unit is developed to form a scaling self-transform function that can self-image on scale. Then an array of many such grating-lens units is used for the optical interconnection of a two-dimensional neural network, and experiments are carried out. We find that our idea is feasible, the optical interconnection system is simple, and optical adjustment is easy. (C) 1998 Optical Society of America.

Effects of annealing on self-organized InAs quantum islands on GaAs (100)

Self-organized InAs islands on (001) GaAs grown by molecular beam epitaxy were annealed and characterized with photoluminescence (PL) and transmission electron microscopy (TEM). The PL spectra from the InAs islands demonstrated that annealing resulted in a blueshift in peak energy, a reduction in intensity, and a narrower linewidth in the PL peak. In addition, the TEM analysis revealed the relaxation of strain in some InAs islands with the introduction of the network of 90 degrees dislocations. The correlation between the changes in the PL spectra and the relaxation of strain in InAs islands was discussed. (C) 1998 American Institute of Physics. [S0003-6951(98)01850-6].