Determination of faropenem in human plasma and urine by liquid chromatography-tandem mass spectrometry

A simple, rapid and sensitive liquid chromatography/electrospray tandem mass spectrometry (LC-MS/MS) quantitative detection method, using cefalexin as internal standard, was developed for the analysis of faropenem in human plasma and urine. After precipitation of the plasma proteins with acetonitrile, the analytes were separated on a C18 reversed-phase column with 0.1% formic acid-methanol (45:55, v/v) and detected by electrospray ionization mass spectrometry in positive multiple reaction monitoring mode. Calibration curves with good linearities (r=0.9991 for plasma sample and r=0.9993 for urine sample) were obtained in the range 5-4000 ng/mL for faropenem. The limit of detection was 5 ng/mL. Recoveries were around 90% for the extraction from human plasma, and good precision and accuracy were achieved. This method is feasible for the evaluation of pharmacokinetic profiles of faropenem in humans, and to our knowledge, it is the first time the pharmacokinetic of faropenem has been elucidated in vivo using LC-MS/MS.     

Comparative studies on adsorption behavior of thionine on gold nanoparticles with different sizes

The adsorption behavior of thionine on gold nanoparticles of two different mean diameters, 18 and 5 nm, was compared by using UV-vis spectroscopy, fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), and quantum chemical calculations. It is found that the addition of small particles makes the monomer peak of thionine finally disappear, and the corresponding dimer peak is significantly increased. Small gold nanoparticles make the equilibrium between the monomer and H-type dimer forms of thionine move largely toward the dimer forms. Due to the stronger binding between thionine and small gold nanoparticles, the fluorescence quenching of thionine by small particles is enhanced compared to large particles, and the quenching is both static and dynamic. TEM images indicate that the addition of thionine results in a heavy clustering for small particles, and the resulting thionine-gold nanoclusters of about 45 nm were obtained. Quantum chemical calculations, which were based on the density functional theory (DFT) at the B3LYP level, and infrared spectroscopic studies show that the nitrogen atoms of the NH(2) moieties of thionine bind to the gold nanoparticle surfaces. For 18 and 5 nm particles, the surface-to-volume atomic ratios are about 0.0597 and 0.2148, respectively. The higher surface-to-volume atomic ratio and the higher surface free energy result in stronger binding of thionine on small particle surfaces, which can be used to modulate the arrangement of dye molecules on particle surfaces, and thus control the properties of organic-inorganic nanocomposite materials.     

Dye-polyoxometalate composite films: self-assembly, thermal and photochemical properties

A series of dye-polyoxometalate composite films were prepared by alternately depositing cationic dye molecules and anionic polyoxometalates such as Keggin-type [BW(12)O(40)](5-) and the sandwich complex [Co(4)(H(2)O)(2)(PW(9)O(34))(2)](10-)via layer-by-layer (LbL) self-assembly method. These cationic dye molecules (MB, AA, TH, BB3, BCB and NB) are heterocyclic planar and rigid phenothiazine and phenoxazine dye molecules with different substituting groups in the side chains. The self-assembly of the films was studied by UV-vis and IR spectra. The results show that the substituting groups of dye molecules such as NH(2) and CH(2)CH(3) have influence on the self-assembly properties. The continuous and regular growth of the films was also dependent upon hydrogen bonding (NHO) formed between the amino groups of dye molecules and oxygen atoms of POMs as well as electrostatic interactions. The investigation of thermal and photochemical treatments of the composite films is also presented. The thermal stability experiments indicate that the composite films of TH with two NH(2) substitute groups and NB with more pi-conjugated system exhibit high thermal stability, whereas the sunlight irradiation results indicate that the composite films of TH have good photochemical stability.     

A novel morphology of aragonite and an abnormal polymorph transformation from calcite to aragonite with PAM and CTAB as additives

The abnormal structure conversion of CaCO3 from calcite to aragonite was investigated with a mixture of polyacrylamide (PAM) and cetyltrimethylammonium bromide (CTAB) as additives by a hydrothermal method. A novel morphology of aragonite, "magnified" cubic shape, was observed. In order to investigate the effects of PAM and experimental temperature on the morphology and phase of CaCO3, the samples were synthesized without any additives and with PAM as template at 90 and 120 degrees C, respectively. The results indicate that both the interaction between the mixed template and the CaCO3 and the elevated experiment temperature play important roles in the process of polymorph transformation.     

Neighboring group participation of phosphine oxide functionality in the highly regio- and stereoselective iodohydroxylation of 1,2-allenylic diphenyl phosphine oxides

Two sets of reaction conditions were established to enable the highly regio- and stereoselective iodohydroxylation of 1,2-allenylic diphenyl phosphine oxides, yielding (E)-2-iodo-3-hydroxy-1-alkenyl diphenyl phosphine oxides with very high stereoselectivity. The scope of this reaction was examined extensively. Notably, studies on the reactivity of optically active substrates indicated that the axial chirality in the starting allenes may be efficiently transferred to the center chirality of the products with no discernible loss of enantiopurity. Due to the importance of phosphine-containing compounds, both as reagents and ligands, this reaction shows potentials in organic synthesis. Investigations using ESI-MS technology on the (18)O-labeled product, which was prepared using (18)O-water as the solvent, indicated that the (18)O atom was bound to phosphorus in the final product and the oxygen atom of the hydroxyl comes from the phosphinyl functionality of the allene reactant. These results provided solid evidence for the formation of a five-membered cyclic intermediate from the neighboring group participation of the diphenylphosphinyl group. To the best of our knowledge, this is the first time that the neighboring group participation of this type of group was observed.     

凝胶渗透色谱-气相色谱-离子阱质谱法测定桔梗原药和当归提取物中101种农药残留

建立了凝胶渗透色谱（GPC）-气相色谱-离子阱质谱同时检测桔梗原药和当归提取物中101种农药残留的分析方法。方法采用乙腈超声辅助提取桔梗原药和当归提取物,浓缩提取液至近干后用乙酸乙酯-环己烷（1∶1, v/v）复溶,采用凝胶渗透色谱法（选取40 cm长、内径20 mm的凝胶渗透色谱柱）对样品进行净化,弃去前段含脂类、色素等杂质的流出液,收集17~30 min洗脱液并旋转蒸发浓缩至近干,甲苯1 mL定容上机。选用DB-5MS毛细管色谱柱分离待测物,通过离子阱质谱实现对101种农药残留的高效检测。方法通过优化前处理条件和离子阱二级质谱参数,有效降低了复杂中药基质对待测化合物的干扰,最大限度提高了样品中农药的定量准确性和回收率,101种农药3水平添加的平均回收率为58.3%~108.9%,每个添加水平10次独立重复测定的相对标准偏差为0.4%~16.5%,检出限（LOD）范围为0.2~40.0 μg/kg,可满足当前韩国、日本、欧洲规定的最大残留限量（maximum residue limits, MRLs）要求。方法具有操作简单快速、灵敏度高、重复性好等特点,凝胶渗透色谱技术的应用克服了固相萃取小柱净化容量不足的弊端,离子阱技术的应用可以进一步排除共流出基体杂质的干扰,提高定量和定性的准确性,检测效果优于常用的气相色谱-质谱法,是对中药中同时分析多种农药残留检测方法的有益补充。     

光催化剂活性位点调控及其光还原CO2制C2 产物研究进展

工业发展与人类活动导致大气中CO₂浓度逐年升高, 引发一系列生态环境问题. 将CO₂光催化转化为高附加值化学物质不仅有利于缓解环境压力,也可以带来额外经济价值. 然而, 由于多电子利用效率低和C―C偶联动力学缓慢, 光还原CO₂制多碳产品面临产率低和选择性差等挑战. 光催化剂活性位点调控能够有效解决上述问题. 我们综述了近几年用于光还原CO₂催化剂表面活性位点设计的研究进展, 主要包括缺陷位点、 金属位点以及掺杂位点等, 从活性位点的角度为光还原CO₂催化剂设计提供新视角, 并对开发高效光催化剂具有启发意义.     

Grain Boundary Electronic Insulation for High-Performance All-Solid-State Lithium Batteries

Sulfide electrolytes with high ionic conductivities are one of the most highly sought for all-solid-state lithium batteries (ASSLBs). However, the non-negligible electronic conductivities of sulfide electrolytes (≈10⁻⁸ S cm⁻¹) lead to electron smooth transport through the sulfide electrolyte pellets, resulting in Li dendrite directly depositing at the grain boundaries (GBs) and serious self-discharge. Here, a grain-boundary electronic insulation (GBEI) strategy is proposed to block electron transport across the GBs, enabling Li−Li symmetric cells with 30 times longer cycling life and Li−LiCoO₂ full cells with three times lower self-discharging rate than pristine sulfide electrolytes. The Li−LiCoO₂ ASSLBs deliver high capacity retention of 80 % at 650 cycles and stable cycling performance for over 2600 cycles at 0.5 mA cm⁻². The innovation of the GBEI strategy provides a new direction to pursue high-performance ASSLBs via tailoring the electronic conductivity.     

Multiple Dynamic Bonds-Driven Integrated Cathode/Polymer Electrolyte for Stable All-Solid-State Lithium Metal Batteries

All-solid-state lithium metal batteries (LMBs) are considered as the promising higher-energy and improved-safety energy-storage systems. Nevertheless, the electrolyte-electrodes interfacial issues due to the limited solid physical contact lead to discontinuous interfacial charge transport and large interfacial resistance, thereby suffering from unsatisfactory electrochemical performance. Herein, we construct an integrated cathode/polymer electrolyte for all-solid-state LMBs under the action of polymer chains exchange and recombination originating from multiple dynamic bonds in our well-designed dynamic supramolecular ionic conductive elastomers (DSICE) molecular structure. The DSICE acts as polymer electrolytes with excellent electrochemical performance and mechanical properties, achieving the ultrathin pure polymer electrolyte thickness (12 μm). Notably, the DSICE also functions as lithium iron phosphate (LiFePO₄, LFP) cathode binders with enhanced adhesive capability. Such well-constructed Li|DSICE|LFP-DSICE cells generate delicate electrolyte-electrodes interfacial contact at the molecular level, providing continuous Li⁺ transport pathways and promoting uniform Li⁺ deposition, further delivering superior long-term charge/discharge stability (>600 cycles, Coulombic efficiency, >99.8 %) and high capacity retention (80 % after 400 cycles). More practically, the Li|DSICE|LFP-DSICE pouch cells show stable electrochemical performance, excellent flexibility and safety under abusive tests.     

Differential and Integral Isoconversional Non‐linear Methods and Their Application to Energetic Materials. III. Non‐isothermal Decomposition Reaction Kinetics of Benzotrifuroxan

The thermal behaviour and decomposition reaction kinetics of benzotrifuroxan (BTF) were determined by TG and DSC techniques. The kinetic parameters of the exothermic decomposition reaction in a temperature programmed mode (the apparent activation energy Ea and pre-exponential factor A) were calculated by a single non-isothermal DSC curve. The E values calculated using the Kissinger and Flynn-Wall-Ozawa equations and integral isoconversional non-linear equations were used to check the validity of activation energy by a single non-isothermal DSC curve. The results show that the kinetic model function in integral form and the values of Ea and A of the decomposition reaction of BTFare , 109.95 kJ•mol－1 and 108.16 s－1, respectively. The values of ∆S≠, ∆H≠ and ∆G≠ of this reaction are －93.15 J•mol－1•K－1, 150.72 kJ•mol－1 and 153.15 kJ•mol－1, respectively. The critical temperature of thermal explosion of BTF is 257.33 ℃.