单分散聚合物微球稳定Pickering乳液法制备大粒径微胶囊相变材料

采用二步加料的分散聚合法制备单分散聚甲基丙烯酸缩水甘油酯(PGMA)微球, 并使其水解, 得到水包油(O/W)型Pickering乳液稳定剂. 在Pickering乳液聚合过程中, 利用相分离机制, 形成了聚苯乙烯(PSt)和 PGMA复合为整体囊壳的微胶囊相变材料. 微胶囊平均粒径达76 μm, 囊芯含量高达83%, 相变焓达到174 J/g, 具有很高的储热容量.     

热物理激光测量中的三维温度场重构方法

针对热物理激光测量中的三维温度场重构问题，进行了几种算法的讨论．对双高斯函数形式的温度分布进行了重构计算，对重构算法进行了检验，对实验过程中可能出现的误差进行了模拟，讨论了它们对重构结果的影响．     

Curve shortening in a Riemannian manifold

In this paper, we study the curve shortening flow in a general Riemannian manifold. We have many results for the global behavior of the flow. In particular, we show the following results: let M be a compact Riemannian manifold. (1) If the curve shortening flow exists for infinite time, and , then for every n > 0, . Furthermore, the limiting curve exists and is a closed geodesic in M. (2) In M × S ¹, if γ₀ is a ramp, then we have a global flow which converges to a closed geodesic in C ^∞ norm. As an application, we prove the theorem of Lyusternik and Fet.      

Layer-specific population rate coding in a local cortical model with a laminar structure

Uncovering the principle of neural coding is essential for understanding how our mysterious brain works. Recent studies have reported the laminar differences of alpha-beta and gamma rhythms in the sensory cortex, yet it remains unclear about the underlying function role of frequency-dependent interlaminar interactions in neural coding. Using a rate-based network model to simulate the cortical laminar under the external time-varying stimuli, we showed that the physiological specificity of rhythms for layers enables the cortical laminae to preferentially encode information in different frequency ranges. The interplay of the supragranular layer and infragranular layer contributes significantly to improving the neural representation of external time-varying input at the population level. Further investigations revealed the essential role of recurrent connections of the cortical laminae in regulating the population rate coding. In particular, the laminar network optimally encodes the time-varying input at intermediate strengths of intralaminar excitatory–inhibitory circuits and interlaminar connections. Additionally, we verified the crucial role of adaptation in improving population coding by introducing slow dynamics and suppressing the noise-like excitatory activity in the laminar network. These findings highlight the crucial role of frequency-dependent interlaminar interactions in encoding time-varying stimuli and may shed light on the underlying function of cortical structural specificity in neural information processing.

     

重液离心分离在研究煤中难燃组分的应用

通过对阳泉煤、淮南煤及神木煤进行重液离心分离，得到了一系列对应于不同密度的分离物。对各密度段样品的热分析表明，煤中存在着对应于一定密度段的难燃组分，它们多是煤中的惰性组，部分矿物质及高矿化性的组分。     

KNbO3:Fe晶体的最佳二波耦合

本文在分析光折变晶体KNbO3:Fe的最佳二波耦合条件的基础上,通过计算和实验研究了晶体KNbO3:Fe的二波耦合增益系数Γ与两光束的夹角2θ、光栅矢量的取向β及不同电光系数r51或r42的关系,获得了在特定掺杂浓度N～1016cm-3条件下KNbO3:Fe晶体的最佳二波耦合条件为:θm～4°-8°并且βm～45°.     

Preparation of Fe3O4 magnetic fluid by one-step method with a microemulsion reactor

A W/O microemulsion was prepared with Span80-PS (petroleum sulfonate) as complex emulsifier, isopropanol as cosurfactant and kerosene as oil phase. The optimal constituents of microemulsion were found from pseudoternary phase diagrams: the mass ratio of Span80 to PS was 4:1 and complex surfactant to cosurfactant was 1:1. The Fe₃O₄ magnetic fluid was obtained by one-step method with the W/O microemulsion as microreactor to synthesize magnetic nanoparticles (reaction temperature was 30 °C and reaction time was 5 h) and kerosene as carrier liquid. The magnetic fluid was investigated by TEM, XRD and fluorescence microscope. The magnetism was determined by Gouy magnetic balance. The average particle size of Fe₃O₄ was 7.4 nm, and magnetic particles were well-dispersed. The stable Fe₃O₄ magnetic fluid with good magnetism may be produced by one-step method in the W/O microemulsion. Accordingly, the traditional preparation method of magnetic fluid can be simplified greatly. __________ Translated from Chinese Journal of Applied Chemistry, 2005, 22 (7) (in Chinese)     

Label‐Free Colorimetric Detection of Trace Atrazine in Aqueous Solution by Using Molecularly Imprinted Photonic Polymers

Based on the combination of colloidal‐crystal templating and a molecular imprinting technique, a sensor platform for efficient detection of atrazine in aqueous solution has been developed. The sensor is characterized by a 3D‐ordered interconnected macroporous structure in which numerous nanocavities derived from atrazine imprinting are distributed in the thin wall of the formed inverse polymer opal. Owing to the special hierarchical porous structure, the molecularly imprinted polymer opals (or molecularly imprinted photonic polymer; MIPP) allow rapid and ultrasensitive detection of the target analyte. The interconnected macropores are favorable for the rapid transport of atrazine in polymer films, whereas the inherent high affinity of nanocavites distributed in thin polymer walls allows MIPP to recognize atrazine with high specificity. More importantly, the atrazine recognition events of the created nanocavities can be directly transferred (label‐free) into a readable optical signal through a change in Bragg diffraction of the ordered macropores array of MIPP and thereby induce color changes that can be detected by the naked eye. With this novel sensory system, direct, ultrasensitive (as low as 10^?8 ng mL^?1), rapid (less than 30 s) and selective detection of atrazine with a broad concentration range varying from 10^?16 M to 10^?6 M in aqueous media is achieved without the use of label techniques and expensive instruments.