Electrochemical Reduction of Carbon Dioxide to Methanol on Hierarchical Pd/SnO2 Nanosheets with Abundant Pd–O–Sn Interfaces

Electrochemical conversion of CO₂ into fuels using electricity generated from renewable sources helps to create an artificial carbon cycle. However, the low efficiency and poor stability hinder the practical use of most conventional electrocatalysts. In this work, a 2D hierarchical Pd/SnO₂ structure, ultrathin Pd nanosheets partially capped by SnO₂ nanoparticles, is designed to enable multi‐electron transfer for selective electroreduction of CO₂ into CH₃OH. Such a structure design not only enhances the adsorption of CO₂ on SnO₂, but also weakens the binding strength of CO on Pd due to the as‐built Pd–O–Sn interfaces, which is demonstrated to be critical to improve the electrocatalytic selectivity and stability of Pd catalysts. This work provides a new strategy to improve electrochemical performance of metal‐based catalysts by creating metal oxide interfaces for selective electroreduction of CO₂.     

Improvement of microemulsion electrokinetic chromatography for measuring octanol-water partition coefficients

Microemulsion electrokinetic chromatography (MEEKC) has been used to indirectly measure octanol-water partition coefficients (log P(ow)) of compounds. In order to obtain an accurate log P(ow) value, the electrophoretic mobilities of the microemulsion phase (mu(me)) and the analyte (mu(eff)) in MEEKC must be accurately required. However, in conventional MEEKC, the shortage of obtaining mu(me) with a tracing method was discovered, and the influences of concentration, injection volume of analyte, and high electric field on measuring mu(eff) were also found. In this paper, a novel method called improved MEEKC (I-MEEKC) was developed to avoid the problems mentioned above. In I-MEEKC, a nonlinearity fitting program was used to obtain mu(me) to avoid the error from tracing mu(me); the extrapolating method was used to eliminate the effects of concentrations and injection volumes of analytes on mu(eff) measurement, and an enough stable microemulsion was selected to eliminate the effect of high electric field on mu(eff )measurement. Then the novel method was applied to estimate log P(ow) of uncharged compounds and charged pharmaceuticals compared to the conventional MEEKC. The log P(ow) of all analytes obtained by I-MEEKC agreed with those obtained by classical shake flask or literature values, the errors between them were within 0.1 logarithm units, better than the ones by conventional MEEKC.     

顶空富集-气相色谱-质谱联用法测定聚醚中3，5-二新丁基-4-羟基-甲苯

采用气相色谱与质谱联用法测定了聚醚中3,5-二新丁基-4-羟基-甲苯(BHT),并采用顶空富集方法,与溶剂萃取富集法比较,此文中提出的顶空分离法具有不需用大量萃取溶剂,简化了操作步骤,加快了分析速度等优点,而所测得的结果与溶剂萃取法相一致.     

高效液相色谱法测定鸡肉中己烯雌酚

采用高效液相色谱法(HPLC)测定鸡肉中己烯雌酚残留量,将碎鸡肉用甲醇超声提取,合并提取液浓缩近干,用甲醇溶解残渣,所得溶液用于 HPLC 测定.Symmetry C,18用作色谱柱,甲醇与0.012 8 mol·L-1 磷酸二氢钠溶液以63比37(体积比)混合后作为流动相,流速为 1.0 mL·min-1.在230 nm波长处,用二极管阵列检测器检测.对鸡肉样品作了分析,测定结果的相对标准偏差(n=5)均小于 10%,回收试验给出回收率在 87.5%～92.3%之间.测得方法的检出限(S/N=3)为 20 μg·kg-1.     

Highly Efficient and Chemoselective Tandem Hydroformylation-Hydrogenation of Alkenes to Alcohols over g-CN Supported Bimetallic Rh and Co Nanoparticles Catalysts

The objective of the tandem hydroformylation-hydrogenation of alkenes to corresponding alcohols was to design an efficient and stable heterogeneous catalyst. To this end, a series of novel heterogeneous graphitic carbon nitride (g-CN) supported bimetallic Rh−Co nanoparticle catalysts (Rh−Co/g-CN) were prepared and subsequently studied for this one-pot two-step reaction. The lamellar structure makes Rh and Co nanoparticles with diameters of <1 nm and 20 nm, respectively, homogeneously deposited on the surface of g-CN layers, exhibit remarkable conversion of styrene (99.9 %) and chemoselectivity for alcohol (87.8 %). More importantly, Co nanoparticles are found to play an important role in the improvement of the chemoselectivity for alcohol due to the formation of catalytic active species [HCo(CO)_y]. Besides the detailed investigation of the catalytic properties of Rh−Co/g-CN under different reaction conditions, the reuse of Rh−Co/g-CN was conducted for five times and no evident decrease in the activity and chemoselectivity was observed. Therefore, we expect that this work could offer an initial insight into g-CN-based heterogeneous catalyst on the tandem hydroformylation-hydrogenation reaction.     

Adaptive impulsive synchronization of uncertain delayed chaotic system with full unknown parameters via discrete‐time drive signals

This article investigates the adaptive impulsive synchronization of delayed chaotic system with full unknown parameters. Aiming at this problem, we propose a new adaptive strategy, in which both the adaptive–impulsive controller and the parameters adaptive laws are designed via the discrete‐time signals from the drive system. The corresponding theoretical proof is given to guarantee the effectiveness of the proposed strategy. Moreover, the concrete adaptive strategies are achieved for delayed Hopfield neural network, optical Ikeda system and the well‐known delayed Lü chaotic system. As expected, numerical simulations show the effectiveness of the proposed strategy. This method has potential applications in parameters estimation, secure communication, and cryptanalysis when only discrete signals are transmitted in communication channel. © 2014 Wiley Periodicals, Inc. Complexity 21: 43–51, 2016     

Efficient and mild swern oxidation using a new sulfoxide and bis(trichloromethyl)carbonate

A new type of sulfoxide, 4-(2-(2-(methylsulfinyl) ethyl)-4-nitrophenyl)- morpholine (I), was designed and prepared in good yield. Upon the combination of I and bis(trichloromethyl)carbonate, the Swern oxidation of primary and secondary alcohols was significantly promoted under mild conditions, which afforded the corresponding aldehydes or ketones in good yields. It is noteworthy that the reoxidation of the isolated by-product sulfide V could be further recycled in Swern oxidation.     

Organic‐Base‐Driven Intercalation and Delamination for the Production of Functionalized Titanium Carbide Nanosheets with Superior Photothermal Therapeutic Performance

The delamination of titanium carbide sheets, an intriguing class of two‐dimensional materials, has been critically dependent on the extraction of interlayer Al in acidic media, such as concentrated hydrofluoric acid (HF) or a mixture of hydrochloric acid (HCl) and a fluoride salt. Herein, we report an organic‐base‐driven intercalation and delamination of titanium carbide that takes advantage of the amphoteric nature of interlayer Al. The resulting aluminum‐oxoanion‐functionalized titanium carbide sheets manifested unusually strong optical absorption in the near‐infrared (NIR) region with a mass extinction coefficient as high as 29.1 L g^?1 cm^?1 at 808 nm. Thus, the performance of this material is comparable or even superior to that of state‐of‐the‐art photoabsorption materials, including gold‐based nanostructures, carbon‐based materials, and transition‐metal dichalcogenides. Preliminary studies show that the titanium carbide sheets serve as efficient photothermal agents against tumor cells.     

Screening and isolation of potential lactate dehydrogenase inhibitors from five Chinese medicinal herbs: Soybean,Radix pueraria,Flos pueraria,Rhizoma belamcandae,and Radix astragali

Stroke is among the leading causes of death and severe disability worldwide. Flavonoids have been extensively used in the treatment of ischemic stroke by reducing lactate dehydrogenase levels and thereby enhancing blood perfusion to the ischemic region. Here, we used ultrafiltration high‐performance liquid chromatography coupled with diode array detection and mass spectrometry for the rapid screening and identification of flavonoids from five Chinese medicinal herbs: soybean, Radix pueraria, Flos pueraria, Rhizoma belamcandae, and Radix astragali. Using PC12 cells as a suitable in vitro model of toxicity, cell viability was quantitated using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. The results showed that the extracts of soybean and the six major components, namely, acetyldaidzin, malonylgenistin, daidiain, glycitin, genistin, and acetylcitin; the extract of R. pueraria and its main component daidzein; the extract of F. pueraria and its three major components, tectorigenin, tectoridin, and tectorigenin‐7‐O‐xylosylglucosid; and the extract of R. belamcandae and its main component, tectoridin, were strong lactate dehydrogenase inhibitors. Also, the components of R. astragali showed no bioactivity. These findings indicate that the ultrafltration high‐performance liquid chromatography coupled with diode array detection and mass spectrometry method could be utilized in rapid screening and separation of bioactive compounds from a complex matrix.     

Sodium tanshinone IIA sulfonate depresses angiotensin II-induced cardiomyocyte hypertrophy through MEK/ERK pathway

Cardiomyocyte hypertrophy is a major cause of morbidity and mortality worldwide. The aim of this study is to determine the effects of sodium tanshinone IIA sulfonate (STS) on cardiomyocyte hypertrophy induced by angiotensin II (Ang II) in vivo and in vitro. In long-term treatment, adult Wistar rats were infused with Ang II for three weeks via osmotic mini-pumps and some of them were given intragastrically of STS. Left ventricle was isolated; the ratio of left ventricular weight to body weight and systolic blood pressure (SBP) were determined and heart morphometry was assessed after hematoxylin and eosin staining. Results indicated STS inhibited Ang II-induced increases in myocyte diameter and decreased the LVW/BW ratio independent of decreasing systolic blood pressure. In vitro, treatment of cultured cardiomyocytes with STS inhibited Ang II-induced increase in cell size, protein synthesis, ANP expression, activation of extracellular signal- regulated kinase (ERK) and ERK kinase (MEK). Then we reexamined the mechanism of STS-induced anti-hypertrophic effects. Results revealed MEK inhibitor U0126 (20 microM) markedly enhanced STS-induced depressions in [(3)H]leucine incorporation and ANP expression. In conclusion, MEK/ERK pathway plays a significant role in the anti-hypertrophic effects of STS.