铁基纳米材料功能化及对水中汞离子的去除

在水体重金属污染中,汞污染问题日益严峻,已成为全球性环境问题之一。近年来,纳米FeS_x、Fe₃O₄、Fe等铁基材料凭借优越的吸附性能以及比表面积优势,受到研究者的广泛关注。对铁基纳米材料进行稳定化、官能团改性之后可以增强纳米粒子的分散度,为汞离子提供更多的吸附点位,进一步加强对水中汞离子的去除效果。本文重点阐述了纳米FeS_x的稳定化、Fe₃O₄等铁基材料的巯基化（-SH）、氨基化（-NH₂）等功能化改性方法及对Hg的去除;总结了功能化铁基纳米材料对水中Hg的去除效果和影响因素;探究了功能化铁基纳米材料去除水中汞的机理;最后展望了铁基功能化纳米材料处理水体汞离子的发展方向。     

人眼晶状体调节机制和力学

晶状体是人眼屈光系统的核心,其视觉调节过程由睫状肌、悬韧带和晶状体共同实现:通过睫状肌牵引悬韧带运动,引起晶状体变形(变凸或扁平),从而改变眼睛的屈光力,使得眼睛聚光的焦点准确地落在视网膜上,最终产生视觉.晶状体的视觉调节从本质上说是一个力学问题,调节过程的实现与视觉质量紧密相关;同时调节机制也是最常见的眼部老化退行性疾病--老视的核心问题.本文介绍了晶状体调节的各种理论假说及其发展,并概述了晶状体的力学性能.     

Comparative study of volatile components from male and female flower buds of Populus × tomentosa by HS-SPME-GC-MS

The differences of volatile components in male (MFB) and female flower buds (FFB) of Populus × tomentosa were analysed and compared by HS-SPME with GC-MS for the first time. A total of 34 compounds were identified. Two clusters were clearly divided into male and female by hierarchical clustering analysis. Both the male and female flower buds showed methyl salicylate (22.83 and 24.09%, respectively) and 2-hydroxy-benzaldehyde (10.05 and 12.41%, respectively) as the main volatile constituents. The content of 2-cyclohexen-1-one, benzyl benzoate, and methyl benzoate in FFB was remarkably higher than in MFB. In contrast, the content of ethyl benzoate in MFB was greater than that in FFB. The phenomena showed the characteristic differences between MFB and FFB of P. × tomentosa, which enriched the basic studies on dioecious plant.     

Sr6Cd2Sb6O7S10: Strong SHG Response Activated by Highly Polarizable Sb/O/S Groups

A new nonlinear optical (NLO) oxysulfide, Sr₆Cd₂Sb₆O₇S₁₀, which contains the functional groups [SbO_xS_5?x]^7? (x=0, 1) with a 5s² electron configuration, is synthesized by a solid‐state reaction. This compound displays a phase‐matchable second harmonic generation (SHG) response four times stronger than AgGaS₂ (AGS) under laser irradiation at 2.09 μm. Single‐crystal‐based optical measurements reveal a SHG intensity that can be tuned by temperature and novel photoluminescence properties. Theoretical analyses demonstrate that tetragonal [SbOS₄]^7? and [SbS₅]^7? pyramids make the predominant contribution to the enhanced SHG effect. Among those, the [SbOS₄]^7? units with mixed anions make a larger contribution. This work proposes that oxysulfide groups with an ns² electron configuration can serve as new functional building units in NLO materials and opens a new avenue for the design of other optoelectronic materials.     

Fast self-healing superhydrophobic sponge with all-weather heating and anti-fouling properties

The loss of superhydrophobicity due to mechanochemical damage is critical for superhydrophobic surfaces, and rapid self-healing is significant in maintaining surface durability. Herein, a novel, fast, self-healing superhydrophobic sponge capable of all-weather heating was polymerized in an eco-friendly aqueous system and dip-coated using fluorine-free and non-toxic reagents. Benefiting from the photothermal and Joule-heating performance of polyaniline (PANI) and multiwalled carbon nanotubes (MWCNTs), all-weather heating could be achieved. The equilibrium surface temperature (EST) of the as-prepared sponge could rapidly reach 105°C under irradiation of 1.0 kW/m² for 20 s, and the EST exceeded 120°C with supplementary 18 V treatment. Impressively, after O₂ plasma etching for 1 min or after being immersed in hydrogen peroxide (H₂O₂) solution for 24 h, the water contact angle (WCA) of self-healing superhydrophobic polyurethane (PU) sponge (SHSPS) can be restored to 155°C under simulated sunlight for 2 min because of the rapid migration of low surface energy polydimethylsiloxane (PDMS) chains, which is the fastest recovery achieved to the best of our knowledge. In addition, the modified sponge exhibited a significant antifouling capability for particulate contaminants and organic pollutants, extending service life. Our preliminary results demonstrated that the modified sponge prepared in the current work is fully qualified in multiple applications, including oil-water separation, viscous oil treatment, seawater evaporation and desalination, de-icing, and anti-icing.     

[Cs6Cl][Ga5GeQ12] (Q = S,Se): two novel porous layered chalcohalides exhibiting two-band emission and ion exchange properties

Science China Chemistry - The salt-inclusion materials have drawn significant attention for their manifold structural chemistry and novel physical/chemical properties. Herein, two new...     

Electrochemical fabrication of silver tips for tip‐enhanced Raman spectroscopy assisted by a machine vision system

Both tip‐enhanced Raman spectroscopy and scanning tunneling microscopy require the use of sharp tips. Electrochemical etching appears to be the most widely used method for preparing tips. To address the over‐etching problem associated with the silver tips by either using voltage or current as a feedback, we developed here an optical method‐based machine vision to achieve a quick cutoff of the circuit once the tip forms. It is a fully automated method with a response time of about 40 ms and is tolerated with any existing electrochemical etching method. We can significantly decrease the time of over‐etching of the silver tip when short rectangular pulses with a duty cycle of 28.6% were used. The mean radius of curvature was ca. 58 nm, as measured from over 50 tips. The capacities of silver tips for high‐resolution scanning tunneling microscopy imaging and high‐sensitivity tip‐enhanced Raman studies have been demonstrated. Copyright © 2016 John Wiley & Sons, Ltd.     

Sulfur(iv)-mediated umpolung α-heterofunctionalization of 2-oxazolines

The α-umpolung of carbonyl compounds significantly expands the boundaries of traditional carbonyl chemistry. Despite various umpolung methods available today, reversing the inherent reactivity of carbonyls still remains a substantial challenge. In this article, we report the first use of sulfonium salts, in lieu of well-established hypervalent iodines, for the carbonyl umpolung event. The protocol enables the incorporation of a wide variety of heteroatom nucleophiles into the α-carbon of 2-oxazolines. The success of this investigation hinges on the following factors: (1) the use of sulfoxides, which are abundant, structurally diverse and tunable, and easily accessible, ensures the identification of a superior oxidant namely phenoxathiin sulfoxide for the umpolung reaction; (2) the “assembly/deprotonation” protocol previously developed for rearrangement reactions in our laboratory was successfully applied here for the construction of α-umpoled 2-oxazolines.

Aryl sulfonium salts serving as a new type of carbonyl umpolung reagent enable direct α-heterofunctionalization of 2-oxazolines.     

Exploring the Interfacial Reaction of Nano Al/CuO Energetic Films through Thermal Analysis and Ab Initio Molecular Dynamics Simulation

The effect of the interface layer on energy release in nanoenergetic composite films is important and challenging for the utilization of energy. Nano Al/CuO composite films with different modulation periods were prepared by magnetron sputtering and tested by differential scanning calorimetry. With the increase in the modulation period of the nano Al/CuO energetic composite films, the interface layer contained in the energetic composite film decreased meaningfully, increasing the total heat release meaningfully. Ab initio molecular dynamics (AIMD) simulation were carried out to study the preparation process changes and related properties of the nano Al/CuO energetic composite films under different configurations at 400 K. The results showed that the diffusion of oxygen atoms first occurred at the upper and lower interfaces of CuO and Al, forming AlO_x and Cu_xAl_yO_z. The two-modulation-period structure changed more obviously than the one-modulation-period structure, and the reaction was faster. The propagation rate and reaction duration of the front end of the diffusion reaction fronts at the upper and lower interfaces were different. The Helmholtz free energy loss of the nano Al/CuO composite films with a two-modulation-period configuration was large, and the number of interfacial layers had a great influence on the Helmholtz free energy, which was consistent with the results of the thermal analysis. Current molecular dynamics studies may provide new insights into the nature and characteristics of fast thermite reactions in atomic detail.     

Sophorolipid Suppresses LPS-Induced Inflammation in RAW264.7 Cells through the NF-κB Signaling Pathway

Objectives: Biosurfactants with anti-inflammatory activity may alleviate skin irritation caused by synthetic surfactants in cleaning products. Sophorolipid (SL) is a promising alternative to synthetic surfactants. However, there are few reports on the anti-inflammatory activity of SL and the underlying mechanism. The purpose of this work is to verify that lipopolysaccharide (LPS)-induced inflammation could be inhibited through targeting the pathway of nuclear factor-κB (NF-κB) in RAW264.7 cells. Methods: The influence of SL on cytokine release was investigated by LPS-induced RAW264.7 cells using ELISA. The quantification of the protein expression of corresponding molecular markers was realized by Western blot analysis. Flow cytometry was employed to determine the levels of Ca²⁺ and reactive oxygen species (ROS). The relative expression of inducible nitric oxide synthase (INOS) and cyclooxygenase-2 (COX-2) was determined by RT-PCR. An immunofluorescence assay and confocal microscope were used to observe the NF-κB/p65 translocation from the cytoplasm into the nucleus. The likely targets of SL were predicted by molecular docking analysis. Results: SL showed anti-inflammatory activity and reduced the release of inflammatory cytokines including interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and nitric oxide (NO). The experimental results show that SL suppressed the Ca²⁺ and ROS levels influx in the LPS-induced RAW264.7 cells and alleviated the LPS-induced expression of iNOS and COX-2, the LPS-induced translocation of NF-κB (p65) from the cytoplasm into the nucleus, and the expression of phosphorylated proteins such as p65 and IκBα. Furthermore, molecular docking analysis showed that SL may inhibit inflammatory signaling by competing with LPS to bind TLR4/MD-2 through hydrophobic interactions and by inhibiting IKKβ activation through the hydrogen bonding and hydrophobic interactions. Conclusion: This study demonstrated that SL exerted anti-inflammatory activity via the pathway of NF-κB in RAW264.7 cells.