Biocatalytic Feedback‐Controlled Non‐Newtonian Fluids

Non‐Newtonian fluids are ubiquitous in daily life and industrial applications. Herein, we report an intelligent fluidic system integrating two distinct non‐Newtonian rheological properties mediated by an autocatalytic enzyme reaction. Associative polyelectrolytes bearing a small amount of ionic and alkyl groups are engineered: by carefully balancing the charge density and the hydrophobic effect, the polymer solutions demonstrate a unique shear thickening property at low pH while shear thinning at high pH. The urea‐urease clock reaction is utilized to program a feedback‐induced pH change, leading to a strong upturn of the nonlinear viscoelastic properties. As long as the chemical fuel is supplied, two distinct non‐Newtonian states can be achieved with a tunable lifetime span. As a proof of concept, we demonstrate how the physical energy‐driven nonequilibrium properties can be manipulated by a chemical‐fueled process.     

基于图像处理的光学谐振腔自准直研究方法

针对我国氧碘化学激光器输出能量不断提高的情况下,主要限制光束质量的因素之一是出光过程中的光腔失调,提出了一种基于图像处理的光学谐振腔自准直研究方法。该研究方法利用氦氖穿腔光通过凹腔镜中心孔,并在凸腔镜后方放置工业相机,在屏幕上方形成一个干涉同心圆环。通过借助OpenCV库中二值化、霍夫圆检测等图像处理的方法,获得干涉同心圆环的圆心坐标,再通过以圆心为中心将图像分成上下左右四个部分,通过判断这四部分亮点像素的数量差值来预估干涉同心圆环的偏移状态,进而获得空腔条件下光学谐振腔发生变化的理论判据。实验结果表明,该方法可以获得相当精准的光学谐振腔失调判据,其失调判据选取左右亮点像素差值30000,上下亮点像素差值45000,为今后失调判据与步进电机自动调腔的结合做好充足的准备。     

化学实验操作技能测试评分者效应研究*

基于Rasch模型对化学实验操作技能测试的评分者效应开展研究。通过对Infit、Outfit、t、怀特图和宽严度波动图等的分析,研究测试中评委的宽严度、内部一致性、外部一致性以及评委与考生间的偏差规律。得到系列减弱化学实验操作技能测试中评分者效应的建议。     

Interaction of different types of nanocages (Al12N12, Al12P12, B12N12, Be12O12, Mg12O12, Si12C12 and C24) with HCN and ClCN: DFT,TD-DFT,QTAIM, and NBO calculations

In this work, the ability of different types of nanocages including Al₁₂N₁₂, Al₁₂P₁₂, Be₁₂O₁₂, B₁₂N₁₂, Si₁₂C₁₂, Mg₁₂O₁₂ and C₂₄ for the adsorption and detection of poisonous gases HCN and ClCN has been investigated, theoretically using the D3 dispersion corrected density functional theory (DFT-D3). The absorption spectra of HCN–nanocage and ClCN–nanocage complexes were calculated by the time-dependent density functional theory (TD-DFT) and compared with the calculated absorption spectrum of isolated nanocage to investigate the ability of nanocage for sensing of HCN and ClCN gases. It was found that the strongest interaction between HCN (ClCN) molecule and nanocage takes place when the molecule is adsorbed via its N atom on the surface of nanocage except for C₂₄. Also, it was shown that the Al₁₂N₁₂ is the best adsorbent for HCN and ClCN gases among the selected nanocages and Si₁₂C₁₂ is the best sensor for the detection of these gases using the electroconductivity and absorption spectroscopy techniques.     

Predicting and researching adsorption configurations of pyridazine on Si(100) surface by means of X-ray spectroscopies in theory

The landscape of organic molecule on Si(100) surface has a great significance for organic functionalisation of Si semiconductor. Several possible adsorption configurations for pyridazine on Si(100) surface have been forecasted by systemic comparison and investigation. The C1s XPS and NEXAFS spectra of these adsorption systems based on density functional theory and full core-hole potential approximation have been calculated. Although the sensibility of XPS to these adsorption configurations is not very strong, these configurations can be absolutely distinguished by NEXAFS spectra, which will bring tremendous reference to the future experimental study. Mode II, III, V and VI have a significantly higher adsorption energy, which are most likely to be present in experiment. In addition, we have made the research on specific sources of the peaks in spectra by analysing their decomposed NEXAFS spectra, the results show that the Carbon atoms which do not bond to surface atoms, make the most contribute to the intensity of characteristic peaks in spectra.     

从科研中提炼出的精细化工专业实验:新型疏水缔合聚合物的制备、表征及性能测定*

结合教师科研项目,推荐一个精细化工专业实验:疏水缔合聚合物的制备、表征及性能测定。通过该实验可以使学生掌握自由基共聚法制备聚合物的基本原理,掌握一些大型仪器的基本操作、聚合物常用的表征手段及结构分析方法,理解疏水缔合聚合物结构与性能之间深层次的理论联系。该实验项目来源于科研,服务于实践,集聚合反应、结构表征、大分子溶液理化性能测试于一体,具有综合性、前沿性、研究性等特点。本实验的开设有利于提高精细化工方向学生的专业实验水平,提升学生的综合探究素质、创新意识及动手能力。     

Sterically Facilitated Intramolecular Nucleophilic NMe2 Group Substitution in the Synthesis of Fused Isoxazoles: Theoretical Study

The influence of steric repulsion between the NMe₂ group and a second ortho-(peri-)substituent in the series of 1-dimethylaminonaphthalene and N,N-dimethylanilene ortho-oximes on the ease of the NMe₂ group’s intramolecular nucleophilic substitution is studied. Possible reaction intermediates for three mechanisms are calculated (ωB97xd/def-2-TZVP), and their free Gibbs energies are compared to model reaction profiles. Supporting experiments have proved the absence of studied reactivity in the case of simple 2-dimethylaminobenzaldoxime, which allowed us to establish reactivity limits. The significant facilitation of NMe₂ group displacement in the presence of bulky substituents is demonstrated. The possibility of fused isoxazoles synthesis via the intramolecular nucleophilic substitution of a protonated NMe₂ group in the aniline and naphthalene series is predicted.     

A rapid,spatially dispersive frequency comb spectrograph aimed at gas phase chemical reaction kinetics

This New Views article will highlight some recent advances in high sensitivity gas detection using direct infrared absorption frequency comb laser spectroscopy, with a focus on frequency comb use in chemical reaction kinetics and our own contribution to this field. Our recently implemented detection technique uses a combination of a 12.9?GHz free spectral range virtually imaged phased array and diffraction grating to spatially disperse the mid-infrared frequency comb onto a camera. Individual frequencies or ‘comb teeth’ of a 250?MHz repetition-rate frequency comb are able to be resolved. High molecular sensitivity is achieved by increasing the interaction path length using a Herriott multipass cell. High spectral resolution, broadband spectral coverage, and high molecular sensitivity are all achieved on an adjustable 1–50 µs timescale, making this frequency comb apparatus ideal for measuring chemical reaction kinetics where multiple absorbing species can be monitored simultaneously. This New Views article will also discuss some of the challenges and decisions that chemists might face in implementing this advanced physics technology in their own laboratory.

Spatially dispersed 250 MHz mid-infrared frequency comb laser, with absorption of some frequencies by a dilute sample of methane.     

Mass‐Spectrometric Observation of Counter Anion Production in SU‐8 Exposed to UV Light and its Use for Dill C Parameter Determination

Photopolymerization is a phenomenon that is the basis of much of today's microfabrication technology and intense research is conducted to improve its control and the characteristics of end products for a variety of applications. The design of microscopic structures often relies on the accurate knowledge and modeling of photopolymer's behavior upon exposure, i.e. the Dill parameters, for each radiation species of interest and therefore the development of flexible characterization techniques is of great importance. SU‐8 is a popular compound that is representative of a whole class that relies on cationic polymerization, where an acid is obtained via photolysis of an onium salt during exposure. Here we report on the observation of SbF₆^? via laser desorption mass spectrometry on SU‐8 exposed to UV light at the wavelength of 365 nm and demonstrate that the yield of this counter‐anion as a function of exposure is consistent with the Dill C parameter value available in the literature. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 967–972