A red-emitting water-soluble fluorescent probe for biothiol detection with a large Stokes shift

A highly water soluble fluorescent probe was developed for sensitive and selective detection of biothiols with a red emission and a large Stokes shift. The probe was successfully applied to detect biothiols both in aqueous solution and in living cells.     

Solvability for second-order three-point boundary value problems at resonance on a half-line

This paper deals with the solvability and uniqueness of the second-order three-point boundary value problems at resonance on a half-line

     

Determination of formaldehyde in foodstuffs by flow injection spectrophotometry using phloroglucinol as chromogenic agent

A spectrophotometric method for the determination of formaldehyde in foodstuffs was described by using phloroglucinol as the chromogenic agent. The reaction between formaldehyde and phloroglucinol could occur rapidly at room temperature under mild conditions. The spectrophotometric measurements were conducted at 474nm of an unstable intermediate orange product of the reaction, which greatly increased the sample throughput. Flow injection technique was used to control the merging and reaction timing of the reagents and sample. A detection limit (3sigma) of 0.023microg ml(-1) was achieved. The relative standard deviation was 0.29% for the determination of 7microg ml(-1) formaldehyde (n=11). The proposed method was applied to the analyses of formaldehyde in several preserved foodstuffs and the results were in good agreement with those obtained by a standard method.     

A dansyl-based fluorescent film: Preparation and sensitive detection of nitroaromatics in aqueous phase

A novel fluorescent film sensor for the detection of nitroaromatics in aqueous phase has been developed via chemical immobilization of dansyl chromophores on an epoxy-terminated self-assembled monolayer on glass slide surfaces. Chemical attachment of the chromophore on the substrate surface endows the present film a satisfying stability and avoids the leaching of the chromophores. Increase in the length of the spacer connecting the sensing element and the substrate results in a dramatic improvement in the performance of the film compared to those with similar structures. Fluorescence quenching experiments demonstrates that in aqueous medium, the emission of the film is more sensitive to nitrobenzene (NB) than to other nitroaromatics, including 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, p-chloronitrobenzene, m-dinitrobenzene, p-dinitrobenzene, and o-chloronitrobenzene, etc. This exceptional result has been rationalized by considering the possible hindrance effect induced by the compact conformation of the long flexible spacer. It is also demonstrated that the NB quenching is static in nature, and the response of the film to NB is fast and reversible.     

The One-Sided Inverse Along an Element in Semigroups and Rings

The concept of the inverse along an element was introduced by Mary in 2011. Later, Zhu et al. introduced the one-sided inverse along an element. In this paper, we first give a new existence criterion for the one-sided inverse along a product and characterize the existence of Moore–Penrose inverse by means of one-sided invertibility of certain element in a ring. In addition, we show that \(a\in S^{\dagger }\bigcap S^{\#}\) if and only if \((a^{*}a)^{k}\) is invertible along a if and only if \((aa^{*})^{k}\) is invertible along a in a \(*\)-monoid S, where k is an arbitrary given positive integer. Finally, we prove that the inverse of a along \(aa^{*}\) coincides with the core inverse of a under the condition \(a\in S^{\{1,4\}}\) in a \(*\)-monoid S.     

Controllable Scission and Seamless Stitching of Metal–Organic Clusters by STM Manipulation

Scanning tunneling microscopy (STM) manipulation techniques have proven to be a powerful method for advanced nanofabrication of artificial molecular architectures on surfaces. With increasing complexity of the studied systems, STM manipulations are then extended to more complicated structural motifs. Previously, the dissociation and construction of various motifs have been achieved, but only in a single direction. In this report, the controllable scission and seamless stitching of metal–organic clusters have been successfully achieved through STM manipulations. The system presented here includes two sorts of hierarchical interactions where coordination bonds hold the metal–organic elementary motifs while hydrogen bonds among elementary motifs are directly involved in bond breakage and re‐formation. The key to making this reversible switching successful is the hydrogen bonding, which is comparatively facile to be broken for controllable scission, and, on the other hand, the directional characteristic of hydrogen bonding makes precise stitching feasible.     

Evaluation of a silicon oxynitride hydrophilic interaction liquid chromatography column in saccharide and glycoside separations

The retention characteristics of a silicon oxynitride stationary phase for carbohydrate separation were studied in hydrophilic interaction chromatography mode. Four saccharides including mono‐, di‐, and trisaccharides were employed to investigate the effects of water content and buffer concentration in the mobile phase on hydrophilic interaction liquid chromatography retention. For the tested saccharides, the silicon oxynitride column demonstrated excellent performance in terms of separation efficiency, hydrophilicity, and interesting separation selectivity for carbohydrates compared to the bare silica stationary phase. Finally, the silicon oxynitride hydrophilic interaction liquid chromatography column was employed in the separation of complex samples of fructooligosaccharides, saponins, and steviol glycoside from natural products. The resulting chromatograms demonstrated good separation efficiency and longer retention compared with silica, which further confirmed the advantages and potential application of silicon oxynitride stationary phase for hydrophilic interaction liquid chromatography separation.     

Fabrication of HRP/Bi_2WO_6 photoenzyme-coupled artificial catalytic system for efficiently degrading bisphenol A

A novel photoenzyme-coupled artificial catalytic system is fabricated by immobilizing horseradish peroxidase(HRP) on the Bi_2WO_6 hollow nanospheres via a facile electrostatic self-assembly process. The obtained Bi_2WO_6/HRP sample not only improves the visible light harvest ability but also promotes the high-efficiency separation of charge carriers. More importantly, the photogenerated electrons and produced H_2O_2 on Bi_2WO_6 directly take part in redox cycle reactions of HRP to induce photoenzyme synergic catalytic effect. In consequence, the degradation activity of Bi_2WO_6/HRP is significantly improved relative to Bi_2WO_6 and HRP for removing bisphenol A(BPA) under the visible light irradiation.This work launches a feasible design strategy for exploiting photoenzyme-coupled artificial catalytic system with special structure to degrade organic pollutants in water efficiently.     

Design and optimization of nano-column array based surface plasmon resonance sensor

In this paper, a surface plasmon resonance fiber sensor based on gold nano-column array instead of gold film is designed and optimized. The finite element method is used to optimize the diameter of the nano-gold column under the consideration of figure of merit, which relates to the sensitivity, resonance wavelength and resonance intensity. The optimized sensor has 70 nm gold nano-column coated on a side polished single mode fiber. The results show that the average sensitivity reaches 5318 nm/RIU when the environmental refractive index changing from 1.33 to 1.39 RIU, which is much higher than those in the conventional surface plasmon resonance structure. The optimizes design will serve a vital foundation to the fabrication of high performance fiber optic surface plasmon resonance sensors based on nano metallic structure.     

高温后钢管活性粉末混凝土的动态力学性能

采用霍普金森压杆装置对高温后钢管活性粉末混凝土(reactive powder concrete-filled steel tube,RPC-FST)进行冲击压缩实验,分析了应变率效应及温度效应对试件动态力学性能的影响。结果表明:高温(200、300 ℃)后RPC-FST仍具有较好的抗冲击能力、延性和完整性;冲击荷载作用下,RPC-FST的应变率效应明显弱于RPC的应变率效应;随着过火温度的提高,RPC-FST的峰值应力逐渐增大,变形能力增强,抗冲击能力提高。动力提高系数随过火温度的提高而增大,说明高温后RPC-FST的应变率效应更显著。