一场科学的辩论赛——谣言有罪盐无罪

Amid five tastes, only salt is indispensable. As a kind of essential nutrition, salt plays a vital role in our daily life. Although the salt is in small particle size, yet it received a lot of rumors. In recent years, rumors on salt have sprung like mushrooms including sea salt, iodized salt, low sodium salt, additive in salt and so on. To stop the rumors from spreading and to clarify that the salt is innocent, a debate competition was applied to tell the truth:rumors are guilty rather than salt!     

cis‐1,4‐specific carbocationic polymerization and copolymerization of 1,3‐dienes initiated by (S,S)‐bis(oxazolinylphenyl)amine chromium complexes

Two new chiral (S,S)‐bis(oxazolinylphenyl)amine chromium dichloride complexes have been synthesized and structurally characterized. In combination with 2 equiv. of borate and an excess of AlR₃, such Cr complexes serve as effective cationic initiators in the stereoregular carbocationic polymerization of 1,3‐dienes such as isoprene (IP) and myrcene (MY), affording cyclized cis‐1,4‐PIPs/PMys (cis‐1,4‐selectivity up to 96%) with cyclic sequence contents ranging from 26% to 87%. Moreover, these Cr initiator systems also exhibit an unprecedented control over sequence distribution of comonomers in the carbocationic copolymerization of IP and MY, preparing novel copolymers with different microstructures from mainly cyclized cis‐1,4‐specific statistical copolymers to cyclic olefin copolymers. The nature of Cr complex, borate, AlR₃, temperature, molar ratio of comonomers has considerable effect on the (co)polymer's yield, stereoselectivity, cyclization, and comonomer sequence distribution. A plausible mechanism is suggested, which gives a new strategy for biomimetic synthesis of natural rubber. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1250–1259     

Properties of polyaniline/carbon nanotube multilayer films in neutral solution and their application for stable low-potential detection of reduced beta-nicotinamide adenine dinucleotide

A conducting polymer, polyaniline (PANI), was successfully assembled with commercially available poly(aminobenzenesulfonic acid)-modified single-walled carbon nanotubes (PABS-SWNTs) via the simple layer-by-layer method. PABS-SWNTs inside the multilayer film can dope PANI effectively and shift its electroactivity to a neutral pH environment, pointing to their potential biological applications. The obtained PANI/PABS-SWNTs multilayer films are very stable and show a high electrocatalytic ability toward the oxidation of reduced beta-nicotinamide adenine dinucleotide (NADH) at a much lower potential (about +50 mV vs Ag/AgCl), which makes it an ideal substrate for NADH detection and offers great promise for developing dehydrogenase-based biosensors depending on NADH as a cofactor. For a six-bilayer sample, the detection limit can go down to 1 x 10(-6) M as detected by the simple cyclic voltammetry method, with a linear detection range for NADH at concentrations between 5 x 10(-6) and 1 x 10(-3) M. The substrate can be used repeatedly for consecutive detection cycles of NADH with a very stable signal.     

双-Keggin型四元杂多化合物[Nd(SiMo7W4O39)2]13-多层膜在化学修饰玻碳电极上的组装及电催化

报道双-Keggin型四元杂多化合物K10H3[Nd(SiMo7W4O39)2]XH2O(简称[Nd(SiMo7W4)2]^13-）聚合物的交替组装多层膜在4-氨基苯甲酸修饰玻碳电极上的制备及其电化学特性。各层的循环伏安行为证明膜的均匀增长，峰电流随层数的增加而增加，与溶液中的电化学行为相比，位于多层膜中的杂多化合物的氧化还原特征峰随着多层膜层数的增加，具有一定程度的形变。该电极具有较高的稳定性。并讨论了pH对其氧化还原行为的影响，考察了该多层膜修饰电极对BrO3^-、HNO2和H2O2等的电催化性能。     

In situ hybridization of PNA/DNA studied label-free by electrochemical impedance spectroscopy

The in situ hybridization kinetics of label-free DNA on mixed monolayers of peptide nucleic acid (PNA) and 6-mercapto-1-hexanol (MCH) on Au electrodes was investigated by electrochemical impedance spectroscopy (EIS) and used to discriminate the fully complementary DNA from the single-base mismatched hybrids.     

Metabolomics study of the effect of Danggui Buxue Tang on rats with chronic fatigue syndrome

Danggui Buxue Tang (DBT), a traditional Chinese medicine (TCM) formula for ‘invigorating qi and enriching blood’, has been reported to produce a good effect on chronic fatigue syndrome (CFS). However, the related mechanism remains largely undetermined. This study devised a metabolomics approach with GC–MS combined with pattern recognition to estimate the extent to which DBT alleviated CFS induced by food restriction and force swimming in rats. After 4 weeks of treatment, the endurance capability of rats was significantly better, and the motionless time was significantly shorter in the DBT group than in the CFS model group. Moreover, the activities of superoxide dismutase and glutathione peroxidase increased, whereas the levels of malondialdehyde, interleukin 6, and tumor necrosis factor alpha decreased in the DBT treatment group. Fifteen significantly changed metabolites were observed in the serum of rats with CFS, which was reversed markedly by DBT treatment. Metabolic pathway analysis showed that DBT could possibly alleviate CFS in rats by regulating the biosynthesis of phenylalanine, tyrosine, and tryptophan and the metabolism of glycine, serine, threonine, glycerolipid, glyoxylate, dicarboxylate, and tyrosine. It was observed that the metabolism of glycine, serine, and threonine was most closely related to the improvement in CFS by DBT treatment. This study showed that DBT could improve CFS effectively, and metabolomics was a powerful means to gain insights into the TCM formulas against CFS.     

甲壳低聚糖的性质和制备研究进展

甲壳素/壳聚糖是地球上蕴藏最丰富的天然高分子有机物之一,但是甲壳素/壳聚糖的分子量大,不易溶于水等普通溶剂,使其应用受到极大限制。由甲壳素/壳聚糖降解制备的甲壳低聚糖,因为具有许多独特的生理活性而日益受到研究者们的关注。本文简述了甲壳低聚糖的多种生物特性,综述了其制备方法,包括化学降解法、物理降解法、生物降解法等,并分析了其未来发展的方向。     

Electrocatalytic Urea Synthesis with 63.5 % Faradaic Efficiency and 100 % N-Selectivity via One-step C−N coupling

Electrocatalytic urea synthesis via coupling N₂ and CO₂ provides an effective route to mitigate energy crisis and close carbon footprint. However, the difficulty on breaking N≡N is the main reason that caused low efficiencies for both electrocatalytic NH₃ and urea synthesis, which is the bottleneck restricting their industrial applications. Herein, a new mechanism to overcome the inert of the nitrogen molecule was proposed by elongating N≡N instead of breaking N≡N to realize one-step C−N coupling in the process for urea production. We constructed a Zn−Mn diatomic catalyst with axial chloride coordination, Zn−Mn sites display high tolerance to CO poisoning and the Faradaic efficiency can even be increased to 63.5 %, which is the highest value that has ever been reported. More importantly, negligible N≡N bond breakage effectively avoids the generation of ammonia as intermediates, therefore, the N-selectivity in the co-electrocatalytic system reaches100 % for urea synthesis. The previous cognition that electrocatalysts for urea synthesis must possess ammonia synthesis activity has been broken. Isotope-labelled measurements and Operando synchrotron-radiation Fourier transform infrared spectroscopy validate that activation of N−N triple bond and nitrogen fixation activity arise from the one-step C−N coupling process of CO species with adsorbed N₂ molecules.     

In situ growth of LiMn2O4 on graphene oxide for efficient lithium extraction by capacitive deionization

Journal of Solid State Electrochemistry - Selective extraction of lithium from brines has attracted significant interests with the rapid development of lithium battery industry. LiMn2O4 (LMO) is a...     

Mixed-phase WO3 Cocatalysts on Hierarchical Si-based Photocathode for Efficient Photoelectrochemical Li Extraction

Photoelectrochemical lithium (Li) extraction can be expected to provide a useful recycle of Li⁺ from waste Li-containing battery, but the process is limited by the photocathodes with poor Li⁺ absorption and low yield rate. Here, we have designed a hierarchical silicon (Si)-based photocathode with mixed-phase tungsten oxide (WO₃) cocatalysts for photoelectrochemical Li extraction under 1 sun illumination, achieving a high Li yield rate of ≈223.0 μg cm⁻² h⁻¹ and an excellent faradaic efficiency of 91.9 % at 0.0817 V versus Li^0/+ redox couple. The WO₃ cocatalysts with the mixture of amorphous and crystalline phase accelerates the Li⁺ insertion and precipitation and enriches the concentration of Li⁺ at the photocathode surface. This robust photoelectrochemical Li extraction system provides a new insight on designing green and efficient route for cyclic utilization of Li resources in the sustainable energy field.