Realization of morphing logic gates in a repressilator with quorum sensing feedback

We demonstrate how a genetic ring oscillator network with quorum sensing feedback can operate as a robust logic gate. Specifically we show how a range of logic functions, namely AND/NAND, OR/NOR and XOR/XNOR, can be realized by the system, thus yielding a versatile unit that can morph between different logic operations. We further demonstrate the capacity of this system to yield complementary logic operations in parallel. Our results then indicate the computing potential of this biological system, and may lead to bio-inspired computing devices.     

锡镍合金电磁屏蔽织物研制与镀层性能研究

在化学镀铜的涤纶织物上于焦磷酸盐体系电沉积均匀致密的锡镍合金层.改变镀液的NiSO4.6H2O、SnCl2.2H2O浓度比可获得不同锡含量、不同色泽的锡镍合金镀层.盐雾实验表明,含锡量为68.96%的电磁屏蔽织物表现出较好的耐蚀性和抗变色性.且其导电性优异,柔软、透气性好,具有柔和的外观,对人体无致敏性,在电磁兼容领域和民用市场有广阔的应用前景.     

溶胶-凝胶技术在织物化学镀活化预处理中的应用

以γ-氨丙基三乙氧基硅烷(KH-550)为先驱体,应用溶胶-凝胶技术在织物表面形成一层凝胶薄膜.由于该薄膜含有氨基和羟基等活性基团,能与钯离子起配位络合作用,阻止钯粒子的团聚,使钯以较高的活性完成织物化学镀.扫描探针显微镜(SPM)及扫描电子显微镜(SEM)观察了施镀前后织物的表面形态.与传统的前处理相比,无需SnCl2敏化,减少污染,缩短工艺流程,降低钯盐用量.     

Impact of woven fabric: Experiments and mesostructure-based continuum-level simulations

Woven fabric is an increasingly important component of many defense and commercial systems, including deployable structures, restraint systems, numerous forms of protective armor, and a variety of structural applications where it serves as the reinforcement phase of composite materials. With the prevalence of these systems and the desire to explore new applications, a comprehensive, computationally efficient model for the deformation of woven fabrics is needed. However, modeling woven fabrics is difficult due, in particular, to the need to simulate the response both at the scale of the entire fabric and at the meso-level, the scale of the yarns that compose the weave. Here, we present finite elements for the simulation of the three-dimensional, high-rate deformation of woven fabric. We employ a continuum-level modeling technique that, through the use of an appropriate unit cell, captures the evolution of the mesostructure of the fabric without explicitly modeling every yarn. Displacement degrees of freedom and degrees of freedom representing the change in crimp amplitude of each yarn family fully determine the deformed geometry of the mesostructure of the fabric, which in turn provides, through the constitutive relations, the internal nodal forces. In order to verify the accuracy of the elements, instrumented ballistic impact experiments with projectile velocities of 22-550 m/s were conducted on single layers of Kevlar^® fabric. Simulations of the experiments demonstrate that the finite elements are capable of efficiently simulating large, complex structures.     

Local elastodynamic stresses in the unit cell of a woven fabric composite

Summary A theoretical study of the local elastodynamic stresses of woven fabric composites under dynamic loadings is presented in this article. The analysis focuses on the unit cell of an orthogonal woven fabric composite, which is composed of two sets of mutually orthogonal yarns of either the same fiber (nonhybrid fabric) or different fibers (hybrid fabric) in a matrix material. Using the mosaic model for simplifying woven fabric composites and a shear lag approach to account for the inter-yarn deformation, a one-dimensional analysis has been developed to predict the local elastodynamic and elastostatic behavior. The initial and boundary value problems are formulated and then solved using Laplace transforms. Closed form solutions of the dynamic displacements and stresses in each yarn and the bond shearing stresses at the interfaces between adjacent yarns are obtained in the time domain for any type of in-plane impact loadings. When time tends to infinity, the dynamic solutions approach to their corresponding static solutions, which are also developed in this article. Solutions of certain special cases are identical to those reported in the literature. Lastly, the dynamic stresses and bond shearing stresses of plain weave composites subjected to step uniform impacts are presented and discussed as an example of the general analytical model. Received 3 May 1999; accepted for publication 22 September 1999     

不分明化拓扑线性空间

给出了不分明化拓扑线性空间的定义,讨论了此类拓扑线性空间的平衡零元邻域系的结构和性质。     

Reversible Wettability Switching of Polyaniline‐Coated Fabric,Triggered by Ammonia Gas

A superhydrophobic polyaniline (PANI)‐coated fabric was prepared by in‐situ doping polymerization in the presence of perfluorosebacic acid (PFSEA) as the dopant. It is found that the PANI‐coated fabric undergoes a change in wettability from superhydrophobic (doped state) to superhydrophilic (de‐doped state) when it is exposed to ammonia gas. In particular, a reversible wettability of the PANI‐fabric is observed when it is doped with PFSEA and de‐doped with ammonium gas. It is proposed that the coordination effect of the pore structure of the polyester fabric, low surface energy of the PFSEA dopant, and reversible doping/dedoping characteristics of PANI results in the reversible wettability of the PANI‐coated fabric from superhydrophobicity to superhydrophilicity. Moreover, the tactic used here may provide a new method to monitor the toxic gas.

     

不完全三值逻辑在语言表达上的相互比较

深入讨论各种命题联结词含量不完全的三值逻辑的语言表达的能力,完全弄明白了三值系统L3,L3,B3,B3,K3,K3,MP的语言表达能力的等效或不等效关系,特别应当指出的一个结论是：中介命题逻辑MP作为一种命题联结词含量不完全的三值系统而言,它和其他命题联结含量不完全的三值逻辑L3,L3Δ,B3,B3Δ,K3,K3Δ的语言表达能力都不等效,从而也由此体现出MP的一种自身特色。     

基于CPLD工作模式可调的线阵CCD驱动电路设计

针对传统驱动电路一旦做出修改,则需对硬件或程序进行改变的缺点,以型号为TCD1707D的线阵CCD为例,介绍了一种工作模式可调的驱动方法.该方法是利用复杂可编程逻辑器件和控制外端结合,通过分别设置内外触发来实现的.在外触发模式下,利用外触发脉冲,可由用户控制CCD的曝光和信号输出时间;内触发时,可以调节CCD的积分时间和驱动频率.为提高信号输出质量,针对EMC问题给出了线阵CCD的外围驱动电路.实验结果表明,该方法调试方便、电路结构简单、集成度较高、输出信号可靠稳定、受干扰小,可配合多种用户需要,对高速精确测量及线阵推扫模式具有一定参考价值.     

Study of flame-retardant finishing of cellulose fibres: Organic–inorganic hybrid versus conventional organophosphonate

The aim of this study was to introduce a non-formaldehyde inorganic–organic hybrid sol–gel flame-retardant precursor (SiOP) containing phosphorous, nitrogen, and silicon and to compare its functional properties with those of the conventional formaldehyde-containing organic flame-retardant agent, organophosphonate (OP). SiOP was used at concentrations of 2%, 4%, and 8%, and OP was used at a concentration of 200 g/dm³. Both agents were applied to 100% cotton (CO) woven fabric by the pad-dry-cure method under the appropriate conditions. The presence of the SiOP and OP coatings on the CO fabric was confirmed by scanning electron microscopy, energy dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy. The results of the vertical tests of flammability and the thermogravimetric analyses showed that the presence of the SiOP coating changed the thermal degradation pathway of the CO fabric and resulted in an increase in the thermo-oxidative stability of the cellulose fibres. The thermo-oxidative stability was enhanced by the addition of higher amount of dry solids. At comparable dry solids contents, OP preserved significantly greater flame retardancy and thermo-oxidative stability than did SiOP. These results indicated that the SiOP precursor could not act as an effective alternative to the OP agent in the flame-retardant protection of CO fabric.