Engineering of super bactericidal cotton using pyridinium/di-N-chloramine siloxane with intensified synergism

Tuning the ratio of complementary biocidal groups in a composite unit is proved to be a tactic to better minimize their weaknesses to realize higher synergism. A silane with precursors of one pyridinium and two N-chloramine sites, 6-(pyridin-4-yl)-3-(3-(trimethoxysilyl)propyl)-1,3,5-triazinane-2,4-dione, was synthesized, hydrolyzed and dehydrocondensed into a silicone modifier on cotton cellulose. Specially, isonicotinaldehyde was ammonolyzed with biuret to produce 6-(pyridin-4-yl)-1,3,5-triazinane-2,4-dione that subsequently reacted with (γ-chloropropyl)trimethoxysilane to synthesize the silane through nucleophilic substitution. The modifier on cotton was quaternized and chlorinated to transform the one pyridine and two amide N–H structures in each unit of the silicone to pyridinium and N-chloramine counterparts. The cationic pyridinium increases the hydrophilicity of the unit and draws anionic bacteria to its two adjacent highly fatal N-chloramine sites, achieving a faster contact-killing rate than not only monofunctionality but also basic synergistic integration of one cationic center and one N-chloramine. This phenomenon is therefore referred to as “intensified synergism” and provides crucial information for the design of more powerful biocides. The pyridinium/di-N-chloramine silicone coating exhibited extraordinary durability towards UV irradiation, washing cycles and long-term storage due to the good UV resistance and chemical inertness of pyridinium and silicone backbone.

Graphic abstract

     

Solid phase microextraction associated with microwave assisted extraction of food products

Veltol® (2-methyl 3-hydroxy 4-pyrone) and Veltol-Plus® (2-ethyl 3-hydroxy 4-pyrone) are patented flavor ingredients in food products. Only Veltol® can occur naturally, but both Veltol® and Veltol-Plus® are often added to food products. In order to monitor the use of these compounds in food products, lower detection limits were needed. The Solid Phase Microextraction (SPME) technique for beverages and SPME coupled with Microwave Assisted Extraction (MAE) for solid food samples were studied. The influence of the pH, salt content, SPME adsorption time, GC inlet conditions, and the conditioning of the SPME fiber were investigated. Different food products were tested including coffee, beverages, chewing gums and potato chips. The coupled MAE and SPME shows good results for solid food samples. The reproducibility of the technique was less than 13%RSD and the detection limit was 10 ppb for Veltol® and 2 ppb for Veltol-Plus® using the SIM mode in GC/MS. The technique also shows good selectivity for the target compounds investigated in different food samples.     

光学相干层析技术在法庭科学中的新应用

光学影像技术是法庭科学物证检验分析的重要技术手段，具有无损、原位、快速等优势。近年来，随着光学影像技术的不断发展，一些新技术、新方法不断被引入法庭科学领域并付诸应用。光学相干层析技术（简称OCT技术）是一种光学断层成像技术，具有无损、高分辨、快速、断层成像的特点，特别是其可以无损地得到材料或生物组织内部的结构信息，突破了传统二维成像只能进行物质表面分析的局限，因此可成为一种很有前景的新型法庭科学光学影像技术。本文首先介绍了自主搭建的一套三维OCT成像系统，并着重介绍了基于该系统应用于法庭科学油漆物证检验、胶带指纹显现和毛囊特征分析等方面的研究。结果表明，OCT技术非常适合用于法庭科学物证检验分析，作为其他检验的先导技术手段，获取样品内部信息，提取新型光学特征参数。由于其采用光纤化技术，还有望实现便携化、小型化，在现场勘查中开展相关应用。     

塞曼原子吸收光谱法测定母乳牛奶中铜锌铁钙镁

为了正确评价母乳和牛奶中几种微量元素的营养价值，着重研究了样品前处理和仪器条件选择。结果发现采用浓ＨＮＯ３＋Ｈ２Ｏ２湿法消化样品，操作简单快速，ＲＳＤ＜７．５％，回收率９６．０％～１０５％．还列举了样品中五种元素含量范围。本法适宜大批临床样品测定。     

A Quencher-Based Blood-Autofluorescence-Suppression Strategy Enables the Quantification of Trace Analytes in Whole Blood

Precise quantification of trace components in whole blood via fluorescence is of great significance. However, the applicability of current fluorescent probes in whole blood is largely hindered by the strong blood autofluorescence. Here, we proposed a blood autofluorescence-suppressed sensing strategy to develop an activable fluorescent probe for quantification of trace analyte in whole blood. Based on inner filter effect, by screening fluorophores whose absorption overlapped with the emission of blood, a redshift BODIPY quencher with an absorption wavelength ranging from 600–700 nm was selected for its superior quenching efficiency and high brightness. Two 7-nitrobenzo[c] [1,2,5] oxadiazole ether groups were introduced onto the BODIPY skeleton for quenching its fluorescence and the response of H₂S, a gas signal molecule that can hardly be quantified because of its low concentration in whole blood. Such detection system shows a pretty low background signal and high signal-to-back ratio, the probe thus achieved the accurate quantification of endogenous H₂S in 20-fold dilution of whole blood samples, which is the first attempt of quantifying endogenous H₂S in whole blood. Moreover, this autofluorescence-suppressed sensing strategy could be expanded to other trace analytes detection in whole blood, which may accelerate the application of fluorescent probes in clinical blood test.     

An integrated approach based on ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry,network pharmacology,and molecular docking to study the key effective compounds and mechanism of action of Platycodi Radix in the treatment of chronic obstructive pulmonary disease

Platycodi Radix (PR) is a valuable herb that is widely used in the treatment of chronic obstructive pulmonary disease in clinics. However, the mechanism of action for the treatment of chronic obstructive pulmonary disease remains unclear due to the lack of in vivo studies. Our study established a novel integrated strategy based on ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry, network pharmacology, and molecular docking to systematically analyze the tissue distribution and active compounds of PR in vivo and the therapeutic mechanism of chronic obstructive pulmonary disease. First, tissue distribution studies have shown that the lung is the organ with the highest distribution of PR compounds. Subsequently, network pharmacology results showed that the tumor necrosis factor signaling pathway, interleukin-17 signaling pathway, and mitogen-activated protein kinase signaling pathway were the critical mechanisms of PR against chronic obstructive pulmonary disease. Ultimately, molecular docking results showed that the key targets were stably bound to the corresponding active compounds of PR. Our study is of great significance for the screening of the key effective compounds and the study of the mechanism of action in traditional Chinese medicine and provides data to support the further development and utilization of PR.     

Metal-free catalytic enantioselective silylation of aromatic aldehydes in water

One-step access to chiral α-hydroxysilanes by metal-free catalytic enantioselective silylation of aromatic aldehydes in water was achieved for the first time.     

Banach空间L~P(Ω)中非齐次不适定椭圆边值问题的最小范数极值解

该文对 Ｂａｎａｃｈ空间 ＬＰ（Ω）中二阶椭圆方程非齐次不适定 Ｎｅｕｍａｎｎ 问题,引入伪变分解的概念,应用Ｂａｎａｃｈ空间几何及［３］中关于Ｂａｎａｃｈ空间中线性算子的Ｍｏｏｒｅ－Ｐｅｎｒｏｓｅ广义逆．证明了上述伪变分解为最小范数极值解,从而为适定的．     

Thermal stress measurement of quartz oscillator module packaging

The thermal stress of the quartz oscillator module packaging is investigated using digital-image correlation method (DICM), and the experimental results are given. Under the quartz oscillator module packaging, the quartz oscillator and the Fe−Sn−Cu alloy frame are joined together with the electroconductive adhesive (PI), and the electroconductive adhesive needs to be cured twice at 150°C and 275°C respectively. As the quartz oscillator and the Fe−Sn−Cu alloy frame have a distinct difference in both thermal expansion coefficients and mechanical properties and in process of packaging temperature rises or drops, the thermal stress is yielded easily. While temperature drops, the normal stress at the quartz oscillator edge is a tensile stress, which can make the quartz oscillator fracture. Project supported by the Natural Science Foundation of Tianjin (013605211).     

Multiple solutions for semilinear elliptic equations with Neumann boundary condition and jumping nonlinearities

We obtain nonconstant solutions of semilinear elliptic Neumann boundary value problems with jumping nonlinearities when the asymptotic limits of the nonlinearity fall in the type (Il), l>2 and (IIl), l?1 regions formed by the curves of the Fucik spectrum. Furthermore, we have at least two nonconstant solutions in every order interval under resonance case. In this paper, we apply the sub-sup solution method, Fucik spectrum, mountain pass theorem in order intervals, degree theory and Morse theory to get the conclusions.