含典型氟-氢邻近与远程耦合的混合物的核磁共振氢谱示例

Two serials of tetrasubstituted benzene compounds containing fluoro group were designed and synthesized. The other three substitutes are sequentially the para, meta, and ortho to fluoro group. The obtained compounds were all mixtures as confirmed by ¹H NMR spectroscopies. The spectra clearly show the proximity and remote interaction between fluorine atom and hydrogen atom. In addition, the two spectra, one showing the overlapping peaks, one not, can be used as the simple and typical example of ¹H NMR spectra of mixtures.     

Aggregation-induced emission: a coming-of-age ceremony at the age of eighteen

Aggregation-induced emission(AIE) has drawn great attention worldwide for its unique optical phenomenon and huge potential applications. Since coined by Ben Zhong Tang et al. in 2001, AIE has been deeply investigated and widely utilized in many important areas, such as organic light-emitting diode(OLED), sensor, and bio-imaging. Herein, we highlight some important progress of AIE in these eighteen years, including the exploration of internal mechanism and potential applications. Furthermore,some other interestingly emissive behaviors, originating but distinguishing from the AIE concept, are presented. It is anticipated an overall understanding about AIE could be easily caught from this short review for scientists, no matter whether they are involved in this exciting and rising research area or not.     

Synthesis and lithium-ion storage performances of LiFe<Subscript>0.5</Subscript>Co<Subscript>0.5</Subscript>PO<Subscript>4</Subscript>/C nanoplatelets and nanorods

Carbon-coated olivine-structured LiFe_0.5Co_0.5PO₄ solid solution was synthesized by a facile rheological phase method and applied as cathode materials of lithium-ion batteries. The nanostructure’s properties, such as morphology, component, and crystal structure for the samples, characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer, Emmett, and Teller (BET) determination, X-ray photoelectron spectroscopy (XPS), and the electrochemical performances were evaluated using constant current charge/discharge tests and electrochemical impedance spectroscopy (EIS). The results indicate that nanoplatelet- and nanorod-structured LiFe_0.5Co_0.5PO₄/C composites were separately obtained using stearic acid or polyethylene glycol 400 (PEG400) as carbon source, and the surfaces of particles for the two samples are ideally covered by full and uniform carbon layer, which is beneficial to improving the electrochemical behaviors. Electrochemical tests verify that the nanoplatelet LiFe_0.5Co_0.5PO₄/C shows a better capacity capability, delivering a discharge specific capacity of 133.8, 112.1, 98.3, and 74.4 mAh g^?1 at 0.1, 0.5, 1, and 5 C rate (1 C?=?150 mA g^?1); the corresponding cycle number is 5th, 11th, 15th, 20th, and 30th, respectively, whereas the nanorod one possesses more excellent cycling ability, with a discharge capacity of 83.3 mAh g^?1 and capacity retention of 86.9% still maintained after cycling for 100 cycles at 0.5 C. Results from the present study demonstrate that the LiFe_0.5Co_0.5PO₄ solid solution nanomaterials with favorable carbon coating effect combine the characteristics and advantage of LiFePO₄ and LiCoPO₄, thus displaying a tremendous potential as cathode of lithium-ion battery.     

Diode-pumped Tm:LuAG laser at room temperature

The lasing characteristics of Tm：LuAG at room temperature are reported. The maximum output power at 2.023-μm wavelength is 4.91 W and the slope efficiency is 25.39%. The mode matching between pump mode and laser mode is optimized by changing the pump beam waist radius and its location. Different output couplers are used to realize the optimal laser output. The relationship between operation temperature and output power is also discussed.     

基于液相色谱-串联质谱的结肠癌血清氧固醇标志物筛选

结肠癌(CC)是全球常见恶性肿瘤之一,发病率呈逐年上升趋势,目前没有有效的标志物用于疾病早期诊断和干预跟踪。胆固醇及其氧化衍生物氧固醇在众多恶性肿瘤发生发展中发挥关键作用。该研究采用液相色谱-串联质谱(LC-MS/MS)技术,对CC临床血清样本中胆固醇及相关10种氧固醇代谢物进行了定性定量分析,并采用偏最小二乘判别分析(PLS-DA)和正交偏最小二乘判别分析(OPLS-DA)进行多元统计分析,发现上述目标代谢物能够较好地区分CC组与健康对照组。为防止数据过拟合,该研究在PLS-DA模型各代谢物变量投影重要性(VIP)基础上,结合最优组分数及K-均值聚类结果,筛选得到3种代谢标志物。通过受试者操作特征曲线(ROC)的曲线下面积(AUC)分析,发现筛选得到的3种潜在标志物联合预测CC达到0.998,说明模型性能优良。GO(基因本体论)富集分析显示3种潜在标志物主要分布在内质网和包被囊泡上,参与胆固醇代谢、运输、低密度脂蛋白重塑等生物进程,发挥胆固醇运输活性和低密度脂蛋白颗粒受体结合的分子功能。KEGG(京都基因与基因组百科全书)通路分析显示3种潜在标志物富集于类固醇生物合成、PPAR(过氧化物酶体增殖物激活受体)信号通路及ABC(ATP结合盒)转运等通路上。该研究为寻找CC标志物及进一步阐明胆固醇及氧固醇在CC发病过程中的作用奠定了一定的基础。     

Effect of methane on magnetron sputtering graphite target deposited films and tribological properties of a-C:H:Ti/a-C:H friction pairs

In this study, we prepared a-C:H films with different nanostructures at different methane flow rates. The effect of the methane flow rate on the tribological properties of 440 steel/a-C:H friction pairs and a-C:H:Ti/a-C:H friction pairs in an atmospheric environment was studied by a reciprocating friction machine. The results show that there is no relationship between the tribological properties of 440 steel/a-C:H friction pair and methane flow rate. The tribological performance of the a-C:H:Ti/a-C:H friction pair was greatly improved. In particular, in the friction pair of a-C:H:Ti/a-C:H with a methane flow rate of 20 sccm, superlubricity is shown, and the wear rate is only 4.04 × 10⁻⁹ mm³/Nm. After tribological experiments, Raman spectroscopy, XPS, and other characterization methods were used to study the relationship between the nanostructure and tribological properties of a-C:H:Ti films and a-C:H prepared with different methane flow rates. This study is great significance to the application of a-C:H:Ti/a-C:H friction pair in mechanical parts under atmospheric environment.     

Optimized Pt-MnOx interface in Pt-MnOx/3DOM-Al2O3 catalysts for enhancing catalytic soot combustion

The catalysts of three-dimensionally ordered macroporous (3DOM) Al₂O₃-supported core-shell structured Pt@MnO_x nanoparticles (3DOM-Pt@MnO_x/Al₂O₃) were successfully prepared by the gas bubbling-assisted membrane reduction-precipitation (GBMR/P) method. Pt@MnO_x core-shell nanoparticles (NPs) are highly dispersed on the inner surface of 3DOM-Al₂O₃ support. Pt@MnO_x/3DOM-Al₂O₃ catalysts, which combine both advantages of high-efficiency soot-catalyst contact by 3DOM-Al₂O₃ structure and the abundant active sites by the optimized Pt-MnO_x interface, exhibit high catalytic activities for soot combustion, and the catalytic activities are strongly dependent on the thickness of MnO_x shell. Among the catalysts, 3DOM-Pt@MnO_x/Al₂O₃-1 catalyst with optimized Pt-MnO_x interface shows the highest catalytic activity for soot combustion, i.e., its values of T₅₀ and S_CO2^m are 351 °C and 98.6%, respectively. The highest density of Pt-MnO_x active sites for adsorption-activation of gaseous O₂ is responsible for enhancing catalytic activity for soot combustion. Pt@MnO_x/3DOM-Al₂O₃ catalysts are promising to practical applications for the emission reduction of soot particles.     

Preparation of epoxidized Eucommia ulmoides gum and its application in styrene‐butadiene rubber (SBR)/silica composites

In this article, we primarily introduced a method to prepare epoxidized Eucommia ulmoides gum (EEUG) and studied its application as interfacial additive in styrene‐butadiene rubber (SBR)/silica composites. We prepared the EEUG from the Eucommia gum extract solution using E. ulmoides leaves pretreated with enzymatic solutions as the raw material, petroleum ether as the solvent, and peracetic acid (CH₃COOOH) as the oxidant under a certain temperature. Accordingly, we focused on studying the effects of a series of factors, such as the mole ratio (γ) of peracetic acid to double bonds of Eucommia gum and reaction time on the epoxidation degree and crystallization degree of Eucommia gum in the epoxidation process, in order to control the properties of the EEUG. Regarding the study of the application of EEUG in SBR/silica composites, we found that the addition of EEUG greatly promoted the properties of SBR/silica composites by improving the dispersion of silica in SBR composites, which possessed excellent mechanical properties, including higher tensile strength, tear strength, 100 and 300% modulus, wear resistance, and low heat buildup. Copyright © 2016 John Wiley & Sons, Ltd.     

An Organic Molecule with Asymmetric Structure Exhibiting Aggregation‐Induced Emission,Delayed Fluorescence,and Mechanoluminescence

Compounds displaying delayed fluorescence (DF), from severe concentration quenching, have limited applications as nondoped organic light‐emitting diodes and material sciences. As a nondoped fluorescent emitter, aggregation‐induced emission (AIE) materials show high emission efficiency in their aggregated states. Reported herein is an AIE‐active, DF compound in which the molecular interaction is modulated, thereby promoting triplet harvesting in the solid state with a high photoluminescence quantum yield of 93.3 %, which is the highest quantum yield, to the best of our knowledge, for long‐lifetime emitters. Simultaneously, the compound with asymmetric molecular structure exhibited strong mechanoluminescence (ML) without pretreatment in the solid state, thus exploiting a design and synthetic strategy to integrate the features of DF, AIE, and ML into one compound.     

The Thermal Stability and Adsorbability of the Mechylated Silica Gel

The methylated silica gel has been produced by the reaction between the surface silanol groups and Clsi(CH3)3 vapor.The adsorption isotherms of acetic acid from carbon tetrachloride onto silica gel and emthylated silica gel heated at various temperatures have been determined at 25℃,and the above mentioned silica gels have been studied by TC and IR.The results indicate:(1) The adsorption of acetic acid from carbon tetrachloried onto methylated silica gel decreased greatly,probably because the concentration of the free hydroxyl groups for methylated silica gel decreased greatly as the IR shows.(2) As the methylated surface was destroyed at 450℃,the adsorption ability was restored when the methylated silica gel treated at>500℃.(3) So long as the methylated silica gel was treated at high temperature,the adsorption ability could be restored owing to that surface free hydroxyl groups were reproduced.