Resonance Rayleigh scattering spectral method for the determination of raloxifene using gold nanoparticle as a probe

When gold nanoparticles were being prepared by sodium citrate reduction method, citrate anions self-assembled on the surface of gold nanoparticles to form supermolecular complex anions with negative charges, and protonated raloxifene (Ralo) was positively charged and could bind with the complex anions to form larger aggregates through electrostatic force and hydrophobic effects, which could result in the remarkable enhancement of the resonance Rayleigh scattering intensity (RRS), and the appearance of new RRS spectra. At the same time, the second-order scattering (SOS) and frequency-doubling scattering (FDS) intensities were also enhanced. The maximum wavelengths were located near 370 nm for RRS, 520 nm for SOS, and 350 nm for FDS, respectively. Among them, the RRS method had the highest sensitivity and the detection limit was 5.60 ng mL⁻¹ for Ralo, and its linear range was 0.05-2.37 μg mL⁻¹. A new RRS method for the determination of trace Ralo using gold nanoparticles probe was developed. The optimum conditions of the reaction and influencing factors were investigated. In addition, the reaction mechanism and the reasons for the enhancement of RRS were discussed.     

Eliminating the hairiness of ramie fabrics by micro-dissolution technology in copper ammonia solution

Cellulose - Ramie is of low cost, non-toxic, degradable but the use of ramie in garments manufacturing is limited due to a large amount of hairiness bringing scratchiness to skin. Herein, a facile...     

Structure prediction,electronic, and mechanical properties of alkali metal MB_(12)(=Be,Mg, Ca,Sr) from first principles

Using the particle swarm optimization algorithm on structural search methods, we focus our crystal structures search on boron-rich alkali metal compounds of MB₁₂(M = Be, Mg, Ca, Sr) with simulation cell sizes of 1–2 formula units(f.u.)at 0 GPa. The structure, electronic, and mechanical properties of MB₁₂ are obtained from the density functional theory using the plane-wave pseudopotential method within the generalized gradient approximations. The formation enthalpies of MB₁₂ regarding to solid metal M and solid alpha-boron suggested the predicted structures can be synthesized except for BeB12. The calculated band structures show MB₁₂(M = Be, Mg, Ca, Sr) are all indirect semiconductors. All the calculated elastic constants of MB₁₂ satisfy the the mechanical stable conditions. The mechanical parameters(i.e., bulk modulus,shear modulus, and Young’s modulus) are derived using the Voigt–Reuss–Hill method. The G/B ratios indicated that the MB₁₂ should exhibit brittle behavior. In addition, the hardness, Debye temperature, universal anisotropic index, and the percentage of anisotropy in compression and shear are also discussed in detail. We hope our results can inspire further experimental study on these boron-rich alkali-metal compounds.     

Determination of PCDD/Fs and dioxin-like PCBs in food and feed using gas chromatography-triple quadrupole mass spectrometry

A method was developed on a gas chromatograph coupled to a triple quadrupole mass spectrometer(GC-MS/MS) for trace level determination of polychlorinated dibenzo-p-dioxins/dibenzofurans(PCDD/Fs) and dioxin-like polychlorinated biphenyls(DL-PCBs) in food and feed. The results demonstrated good sensitivity and repeatability for PCDD/Fs and DL-PCBs at an extremely low level(10 pg mL~(-1) for 2,3,7,8-TCDD/F), as well as wide linear response of over 3 or 4 orders of magnitude in concentration ranges; 0.5–200 ng mL~(-1) for PeCDD/F and 0.2–2000 ng mL~(-1) for DL-PCBs. The method detection limits for PCDD/Fs and DL-PCBs were in the range from 0.018–0.17 pg g~(-1) to 0.13–0.36 pg g~(-1), respectively. The performance of the GC-MS/MS for food and feed sample analysis showed high precision and accuracy compared to the high resolution gas chromatograph/high resolution mass spectrometer. The results indicated the feasibility of GC-MS/MS as a confirmatory method for the measurement of PCDD/Fs and DL-PCBs in food and feed as required by European Union legislation.     

Macroscopic atom-molecule dark state and its collective excitations in fermionic systems

We show that a robust macroscopic atom-molecule dark state can exist in fermionic systems, which represents a coherent superposition between the ground molecular Bose-Einstein condensates and the atomic BCS paired state. We take advantage of the tunability offered by external laser fields, and explore this superposition for demonstrating coherent oscillations between ground molecules and atom pairs. We interpret the oscillation frequencies in terms of the collective excitations of the dark state.     

A novel and facile synthesis of 4-arylquinolin-2(1H)-ones under metal-free conditions

A novel and facile synthesis of 4-arylquinolin-2(1H)-ones without metal catalysis has been developed. This reaction involved cyclization/elimination steps and was performed under metal-free conditions using inexpensive reagents such as NaI, selectfluor and KOH.     

磁性和非磁性元素掺杂的自旋梯状化合物Sr_(14)(Cu_(0.97)M_(0.03))_(24)O_(41)(M=Zn,Ni,Co)的结构和电输运性质

利用固相反应法制备了Sr14Cu24O41及其系列B位掺杂Sr14(Cu0.97M0.03)24O41(M=Zn,Ni,Co)的样品.X射线衍射分析显示,所有样品均为纯相,晶格常数a与c没有明显的变化;Zn掺杂样品晶格常数b没有明显变化,而Ni,Co掺杂样品晶格常数b分别稍有增加.选区电子衍射研究揭示:磁性元素Ni,Co及非磁性元素Zn掺杂,可能主要替代了Sr14Cu24O41结构中自旋链上的Cu原子,从而影响了自旋链上的dimer排列,破坏电荷有序超结构.电输运测量显示:Zn2+,Ni2+,Co3+离子掺杂样品的电阻率降低,但仍体现半导体行为,所有的掺杂样品都存在一个渡越温度Tρ,当TTρ时,其导电机理是以单空穴热激发导电占主要地位,在TTρ时,配对的局域化空穴的一维变程跳跃导电占主要优势;在相同的掺杂量下,非磁性元素Zn掺杂对电阻率值的影响大于磁性元素Ni,Co掺杂的影响,而磁性元素Ni,Co掺杂对渡越温度Tρ的影响大于非磁性元素Zn掺杂的影响.     

A bifunctional probe for Al3+ and Zn2+ based on diarylethene with an ethylimidazo[2,1-b]thiazole-6-hydrazide unit

A new diarylethene with ethylimidazo[2,1-b]thiazole-6-hydrazide unit was synthesized, and its photochromic and fluorescent behaviors have been systematically investigated by the stimulation of lights and metal ions in methanol. This new diarylethene exhibited high selectivity and sensitivity toward Al³⁺ and Zn²⁺. The addition of Al³⁺ and Zn²⁺ displayed excellent colorimetric response behaviour with the concomitant color change from colorless to yellow, which could be easily observed by the naked eye. Upon addition of Al³⁺, the fluorescence intensity was enhanced by 180–fold and the emission peak of 1O–Al³⁺ blue-shifted by 15?nm accompanied with a color change from colorless to bright blue. In contrast, when stimulated with Zn²⁺, its fluorescence intensity was enhanced by 35–fold and the emission peak of 1O–Zn²⁺ red-shifted by 16?nm with an evident color change from black to bright green. The LOD for Al³⁺ and Zn²⁺ were determined to be 2.97?×?10^?9?mol?L^?1 and 5.98?×?10^?9?mol?L^?1, respectively. Moreover, a logic circuit was constructed with the fluorescence intensity as the output signal responding to the light and chemical species as the inputs.     

高性能锂-空气电池材料的研究

以锂为负极,空气为正极的锂-空气二次电池,由于其较高的理论能量密度(5 210 Wh.kg-1)而成为最具发展潜力的新型高能化学电源体系。通过近几年的研究和开发,人们对这一体系的了解不断深入。虽然对其电化学过程中的复杂反应机理尚没有完整系统的理论描述,但是在氧还原催化剂、空气电极材料及电解质材料等方面已开展了一些研究工作。本文综述了锂-空气电池的最新研究进展,对电池的正极材料、电解质和负极材料三个方面的研究进行了介绍,分析了该体系的缺陷及存在的问题,并展望了锂-空气电池的发展方向和前景。     

Photocrosslinkable chitosan hydrogels and their biomedical applications

Chitosan is a bioactive macromolecule with a wide variety of applications due to its excellent biological properties such as biodegradability, biocompatibility, and antibacterial activity, and so forth. This highlight focuses on the preparation of photoactive chitosans, the formation of photocrosslinkable chitosan hydrogels, and the related photopolymerization mechanisms. Moreover, the great potential applications of photocrosslinkable chitosan hydrogels for human tissues are also discussed. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1862–1871