Photoresponsive biodegradable poly(carbonate)s with pendent o‐nitrobenzyl ester

Photoresponsive amphiphilic diblock poly(carbonate)s mPEG₁₁₃‐b‐PMNC_n with pendent o‐nitrobenzyl ester group were synthesized through ring‐opening polymerization (ROP) using 1,8‐diazabi‐cyclo[5.4.0]undec‐7‐ene (DBU) as catalyst and monomethoxy poly(ethylene glycol) (mPEG) as macroinitiator. In aqueous solution, the copolymers can self‐assemble to spherical micelles with a PC core and a PEG shell. The critical micelle concentration (CMC), size, and morphology of the micelles were demonstrated by means of fluorescence spectroscopy, transmission electron microscopes (TEM), and dynamic light scattering (DLS). Under UV light irradiation, the amphiphilic copolymer micelles disassembled because of the photocleavage of o‐NB ester, and the light‐controlled release behaviors of payload Nile red were further proved. This study provides a convenient way to construct smart poly(carbonate)s nanocarriers for controlled drug release. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2770–2780     

Characterization of moisture-sensitive raw materials with simple spectroscopic techniques

The quality of raw materials used in a synthetic process needs to be properly controlled in order to ensure optimal reaction conversion and desired quality of the resulting product. For air and water sensitive raw materials, quantitative analysis can be a challenging task. Spectroscopic techniques possess advantages of simple operation, fast analysis, low consumable costs and high sample throughput for the analysis of reactive raw materials. Three case studies utilizing spectroscopic analysis for air and water sensitive materials are discussed. First, FT-IR spectroscopy was utilized to determine the amount of residual acetic acid in acetic anhydride key raw material. Acetic anhydride was used in a methylenation reaction where the presence of residual acetic acid could quench a base used in the reaction, leading to incomplete conversion. A simple, one-frequency calibration method was developed to quantify acetic acid in acetic anhydride (2-35 wt.%). Next, a novel near infrared reflectance spectroscopy (NIRS) method was used to determine the concentration of diisobutyl aluminum hydride (DIBAL-H) in toluene. DIBAL-H is a highly reactive and moisture-sensitive reagent used as a key raw material for the reduction of an active intermediate. A calibration method based on one-frequency was also developed to determine the concentration of DIBAL-H in toluene (0-1.5 mole/L). Finally, a NIRS method based on partial least squares regression (PLS) was developed to quantify p-toluenesulfonic acid in p-toluenesulfonic anhydride, which is not amenable to chromatographic analysis.     

Effect of morphology on organic thin film transistor sensors

This review provides a general introduction to organic field-effect transistors and their application as chemical sensors. Thin film transistor device performance is greatly affected by the molecular structure and morphology of the organic semiconductor layer. Various methods for organic semiconductor deposition are surveyed. Recent progress in the fabrication of organic thin film transistor sensors as well as the correlation between morphology and analyte response is discussed.     

Synthesis and characterization of biodegradable pH-sensitive hydrogels based on poly(?-caprolactone), methacrylic acid, and poly(ethylene glycol)

In this work, a novel biodegradable pH-sensitive hydrogel based on poly(?-caprolactone) (PCL), methoxpoly(ethylene glycol) (MPEG) and methacrylic acid (MAA) was prepared by UV-initiated free radical polymerization. The resulting macromonomers and hydrogels were characterized by FTIR and/or ¹H NMR. Swelling behaviour and pH sensitivity of the hydrogels were studied in detail. With increase in pH of aqueous medium from 1.2 to 7.2, swelling ratio of the hydrogels increased accordingly. The hydrolytic degradation behaviour was also investigated. The prepared biodegradable pH-sensitive hydrogel based on PCL, MPEG, and MAA might have great potential application in smart drug delivery system.     

Bayesian isotonic changepoint analysis

A general approach to Bayesian isotonic changepoint problems is developed. Such isotonic changepoint analysis includes trends and other constraint problems and it captures linear, non-smooth as well as abrupt changes. Desired marginal posterior densities are obtained using a Markov chain Monte Carlo method. The methodology is exemplified using one simulated and two real data examples, where it is shown that our proposed Bayesian approach captures the qualitative conclusion about the shape of the trend change.     

Study on the redox reactions for organic dyes and S‐nitrosylated peptide in electrospray droplet impact

Reduction of analytes in ionization processes often obscures the determination of molecular structure. The reduction of analytes is found to take place in various desorption/ionization methods such as fast atom bombardment (FAB), secondary ion mass spectrometry (SIMS), matrix‐assisted laser desorption/ionization (MALDI) and desorption ionization on porous silicon (DIOS). To examine the extent of the reduction reactions taking place in electrospray droplet impact (EDI) processes, reduction‐sensitive dyes and S‐nitrosylated peptide were analyzed by EDI. No reduction was observed for methylene blue. While methyl red has a lower reduction potential than methylene blue, the reduction product ions were detected. For S‐nitrosylated peptide, protonated molecule ion [M + H]⁺ and NO‐eliminated molecular ion [M − NO + H]^+• were observed but reduction reactions are largely suppressed in EDI compared with that in MALDI. As such, the analytes examined suffer from little reduction reactions in EDI. Copyright © 2008 John Wiley & Sons, Ltd.     

用于叶轮机内流测量的压力敏感涂料校准实验

本文介绍了用于叶轮机械内部流动测量的PSP技术校准系统的组成及校准实验结果。通过对所采集实验图像数据的计算处理,得到了校准特性曲线,与文献的结论基本吻合.同时还对特性曲线的影响因素进行了分析.     

Synthesis of Near‐Infrared Responsive Gold Nanorod/PNIPAAm Core/Shell Nanohybrids via Surface Initiated ATRP for Smart Drug Delivery

Nanosized near infrared (NIR) responsive nanohybrids are synthesized by surface‐initiated atom transfer radical polymerization (SI‐ATRP) of N‐isopropylacrylamide (NIPAAm) on gold nanorods (Au NRs). Transmission electron microscopy images demonstrate that the nanohybrids have a clear core/shell structure. Temperature‐variable ¹H NMR spectroscopy, quasi‐elastic light scattering (QELS), UV‐vis spectroscopy, and laser irradiation prove that the nanohybrids are both temperature and NIR responsive. Norvancomycin (NVan) loading and release experiments show that the drug release rate can be modulated by NIR irradiation. Such an intelligent drug‐delivery system might find applications in non‐invasive controlled drug release in future.

     

一维PSD瞬态响应特性的有限差分方法研究

基于有限差分方法,提出了一种新的PSD RC网络传输线模型模拟算法.利用该算法,得到了一维PSD在不同光信号激励下,从开始响应到进入稳态后的各个阶段的精确数值解.揭示了PSD电极对不同照射点的起始响应时间的差异正相关于光入射点与PSD几何中心之间的距离.在高速瞬态探测时,PSD器件参数限制了激励光脉冲信号的频率,其最高调制速率为1/(3.75Tc).模拟计算结果证明了PSD稳态位置响应结果与入射光类型和时间无关.     

一种新型液体浓度检测系统研究

以光电位置敏感器件作为接收器件,提出了一种利用双折射光透方法的液体浓度检测系统.该系统主要由半导体激光器、光学系统、位置敏感器件信号调理电路、单片机系统、A/D转换电路和显示电路组成.该检测方法的准确性进行了理论分析和实验仿真,并分析了影响检测结果的主要因素.实验表明,温度漂移和光源强度对本系统的影响非常小.