Mechanistic Study of the Titanocene(III)‐Catalyzed Radical Arylation of Epoxides

An atom‐economical and catalytic arylation of epoxide‐derived radicals is described. The key step of the catalytic system is a sequential electron and proton transfer for the rearomatization of the radical σ‐complex and catalyst regeneration. Kinetic, computational, spectroscopic, and cyclovoltammetric investigations highlight the key issues of the reaction mechanism and catalyst stabilization by collidine hydrochloride. Studies employing radicophiles rule out the participation of cations as reactive intermediates.     

Cationic Titanocene(III) Complexes for Catalysis in Single‐Electron Steps

By exploiting solvent and anion effects, [Cp₂Ti]⁺ complexes for atom‐economical catalysis in single‐electron steps were developed and applied for the first time. These complexes constitute remarkably stable and active catalysts for radical arylations. The reaction kinetics and catalyst composition were studied by cyclic voltammetry and in situ IR spectroscopy.     

Chemical Composition Analysis,Cytotoxic, Antimicrobial and Antioxidant Activities of Physalis angulata L.: A Comparative Study of Leaves and Fruit

Physalis angulata L. belongs to the family Solanaceae and is distributed throughout the tropical and subtropical regions. Physalis angulata leaf and fruit extracts were assessed for in vitro anticancer, antioxidant activity, and total phenolic and flavonoid content. The GC-MS technique investigated the chemical composition and structure of bioactive chemicals reported in extracts. The anticancer activity results revealed a decrease in the percentage of anticancer cells’ viability in a concentration- and time-dependent way. We also noticed morphological alterations in the cells, which we believe are related to Physalis angulata extracts. Under light microscopy, we observed that as the concentration of ethanolic extract (fruit and leaves) treated HeLa cells increased, the number of cells began to decrease.     

Single Stage Tandem Mass Spectrometry Assignment of the C-5 Uronic Acid Stereochemistry in Heparan Sulfate Tetrasaccharides using Electron Detachment Dissociation

The analysis of heparan sulfate (HS) glycosaminoglycans presents many challenges, due to the high degree of structural heterogeneity arising from their non-template biosynthesis. Complete structural elucidation of glycosaminoglycans necessitates the unambiguous assignments of sulfo modifications and the C-5 uronic acid stereochemistry. Efforts to develop tandem mass spectrometric-based methods for the structural analysis of glycosaminoglycans have focused on the assignment of sulfo positions. The present work focuses on the assignment of the C-5 stereochemistry of the uronic acid that lies closest to the reducing end. Prior work with electron-based tandem mass spectrometry methods, specifically electron detachment dissociation (EDD), have shown great promise in providing stereo-specific product ions, such as the B₃ ^´ –CO₂, which has been found to distinguish glucuronic acid (GlcA) from iduronic acid (IdoA) in some HS tetrasaccharides. The previously observed diagnostic ions are generally not observed with 2-O-sulfo uronic acids or for more highly sulfated heparan sulfate tetrasaccharides. A recent study using electron detachment dissociation and principal component analysis revealed a series of ions that correlate with GlcA versus IdoA for a set of 2-O-sulfo HS tetrasaccharide standards. The present work comprehensively investigates the efficacy of these ions for assigning the C-5 stereochemistry of the reducing end uronic acid in 33 HS tetrasaccharides. A diagnostic ratio can be computed from the sum of the ions that correlate to GlcA to those that correlate to IdoA.

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Determination of refractive and volatile elements in sediment using laser ablation inductively coupled plasma mass spectrometry

Wet-milling protocol was employed to produce pressed powder tablets with excellent cohesion and homogeneity suitable for laser ablation (LA) analysis of volatile and refractive elements in sediment. The influence of sample preparation on analytical performance was also investigated, including sample homogeneity, accuracy and limit of detection. Milling in volatile solvent for 40 min ensured sample is well mixed and could reasonably recover both volatile (Hg) and refractive (Zr) elements. With the exception of Cr (−52%) and Nb (+26%) major, minor and trace elements in STSD-1 and MESS-3 could be analysed within ±20% of the certified values. Comparison of the method with total digestion method using HF was tested by analysing 10 different sediment samples. The laser method recovers significantly higher amounts of analytes such as Ag, Cd, Sn and Sn than the total digestion method making it a more robust method for elements across the periodic table. LA-ICP-MS also eliminates the interferences from chemical reagents as well as the health and safety risks associated with digestion processes. Therefore, it can be considered as an enhanced method for the analysis of heterogeneous matrices such as river sediments.     

荧光介孔二氧化硅纳米粒子的合成及药物运输

合成了荧光介孔二氧化硅纳米粒子（MSNs-FITC）,并研究了其在持续药物释放和生物示踪成像方面的应用。首先,采用一步法合成出MSNs-FITC,结合SEM、TEM、FT-IR、XRD和氮气吸附脱附等表征技术进行表征。其次,将抗癌药物阿霉素（DOX）负载到MSNs-FITC中。载药粒子的药物释放行为具有明显的pH依赖性,酸性环境加速释放速率。同时,体外细胞毒性测试表明MSNs-FITC具有良好的生物相容性。激光共聚焦扫描显微镜（CLSM）图像表明,MSNs-FITC可以进入细胞并具有剂量依赖性,流式细胞术分析（FCM）进一步证明了这一结果。     

Electrospun nanofibers as sorbent material for solid phase extraction

Electrospinning has emerged as the most versatile technique for nanofiber fabrication. Owing to their large surface area to volume ratio, electrospun nanofibers have the potential to serve as a good sorbent material for solid phase extraction (SPE) based techniques. The ability to incorporate a variety of functionalities prior or post-electrospinning presents a platform to tune the sorbents for specific applications. It is the aim of this contribution to highlight some of the recent developments that harness the great potential of electrospun nanofibers as sorbents for SPE. The review discusses the various ways in which the electrospinning technique addresses two important parameters for sorbent material, which are sorptive capacity and selectivity. It concludes by presenting and discussing the potential for development of SPE format technology and configurations based on electrospun nanofibers.