Silylation of Alcohols and Phenols Using Hexamethyldisilazane Catalyzed by N,N’-Diiodo-N,N’-1,2-ethanediyl Bis(p-toluenesulfonamide) Under Solvent-Free and Microwave Conditions

N,N′-Diiodo-N,N′-1,2-ethanediyl bis(p-toluenesulfonamide) (NIBTS) is an effective catalyst for the silylation of alcohols and phenols using hexamethyldisilazane under solvent-free and microwave conditions.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Lipid Biomarkers of Lens Aging

Lipids are important structural components of cell membranes and have profound effect on membrane fluidity. Lipid profiling and lipidomics have captured increased attention due to the well-recognized roles of lipids in numerous human diseases. Investigating lipid profiles not only provides insights into the specific roles of lipid molecular species in health and diseases, but can also help in identifying potential preventive or therapeutic biomarkers. Cataract, the loss of transparency of eye lens, is a disease of protein aggregation. There are several factors contributing to the stability in protein conformation. Age-related changes in lipid composition could be a contributing factor for altered protein–lipid interaction leading to protein aggregation and cataract. Keeping this in view, in the present study, fatty acid profiling from different age groups of lenses was carried out, using a freshwater catfish as the model. Total lipids were extracted from lenses of three different age groups of fishes (young, adult, and aged) and fatty acid methyl esters (FAME) were prepared and FAME analysis was carried out using gas chromatography–mass spectrometry. The results showed that three fatty acids viz. heneicosylic acid (C21), docosahexaenoic acid (C22:6), nervonic acid (C24:1) which were not present in the adult lens, appeared in the aged lens. On the other hand, eicosenoic acid (C20:1) present in the adult lens was found to be absent in the aged lens. The appearance or disappearance of these fatty acids can possibly serve as biomarkers of aging lens which is the most vulnerable stage for cataract development.     

Core/shell nanoparticles in biomedical applications

Nanoparticles have several exciting applications in different areas and biomedial field is not an exception of that because of their exciting performance in bioimaging, targeted drug and gene delivery, sensors, and so on. It has been found that among several classes of nanoparticles core/shell is most promising for different biomedical applications because of several advantages over simple nanoparticles. This review highlights the development of core/shell nanoparticles-based biomedical research during approximately past two decades. Applications of different types of core/shell nanoparticles are classified in terms of five major aspects such as bioimaging, biosensor, targeted drug delivery, DNA/RNA interaction, and targeted gene delivery.     

室温下以原位生成的醋酸咪唑鎓盐为催化剂和酰化剂用于醇、酚和胺的乙酰化反应(英文)

Acylimidazolium acetate was readily prepared in situ from the reaction of imidazole with acetic anhydride and subsequently acted as a catalyst and acylating agent for the efficient acetylation of alcohols, phenols, and amines at ambient temperature.     

Facile and eco-benign synthesis of a novel MnFe2O4@SiO2@Au magnetic nanocomposite with antibacterial properties and enhanced photocatalytic activity under UV and visible-light irradiations

The purpose of this research is to prepare novel, inexpensive, eco-friendly and efficient magnetic nanocomposites for degradation of pollutant from wastewater and their potential antibacterial activity. To reach this goal, we have synthesized magnetic MnFe₂O₄@SiO₂@Au (MnFe@Si@Au) nanocomposites through ultrasound assisted co-precipitation technique in presence of carbohydrate and Crataegus fruits extract, for the first time. The influence of capping agents including sucrose, glucose, PVA and reducing agents such as C. microphylla and C. pentagyna on the morphology, size, purity, photocatalytic and antibacterial behavior of magnetic nanocomposites were investigated. The FT-IR, XRD, VSM, EDS, FE-SEM, TEM and BET analysis were performed to confirm the formation of magnetic nanocomposites. MnFe@Si@Au nanocomposites have shown promising potential in degradation of organic contaminants including rhodamine b (RhB), 2-naphthol (2-NPH), methyl violet (MV), erythrosine (ER) and eriochrome black T (EBT) under both radiation conditions. The results show that degradation of the anionic contaminants is more than cationic contaminants under UV and visible irradiations. As well as, these synthesized spherical MnFe@Si@Au nanocomposites show excellent antibacterial activities against P. aeruginosa, K. pneumoniae and P. mirabilis bacteria. In addition to the features mentioned, another prominent feature of this nanocatalyst is retaining their photocatalytic activity after five cycles of utilization.     

The application of copolymer-coated graphene oxide-Fe3O4 in the highly efficient synthesis of 2′-aminospiro[indeno[1,2-b]quinoxaline-11,4′-[4'H] pyran]-3′-carbonitrile and 2′-aminospiro[indeno-2,4′-[4'H]pyran]-3′-carbonitrile

A magnetic nanocomposite based on graphene oxide was prepared. Fe₃O₄ nanoparticles were loaded on graphene oxide sheets and GO-Fe₃O₄ was covered by aniline-pyrrole copolymer to afford poly(Py-co-Ani)@GO-Fe₃O₄. This nanocomposite was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy techniques, and its catalytic activity was evaluated in the multicomponent synthesis of 2′-aminospiro[indeno[1,2-b]quinoxaline-11,4′-[4'H]pyran]-3′-carbonitrile and 2′-aminospiro[indeno-2,4′-[4'H]pyran]-3′-carbonitrile derivatives. This magnetically separable catalyst is heterogeneous noncorrosive, highly efficient, and reusable.     

Dimethyldioctadecylanimonium bentonite immobilized magnetic chitosan nanoparticles as an efficient adsorbent for vortex-assisted magnetic dispersive micro-solid-phase extraction of celecoxib from human breast milk,plasma and urine samples

A polymer/layered silicate composite based on dimethyldioctadecylanimonium bentonite/chitosan magnetic nanoparticles was synthesized and characterized by field emission transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectrometry. The prepared nanocomposite was used to isolate and preconcentrate celecoxib from human breast milk, urine and plasma samples. In this method, dimethyldioctadecylanimonium bentonite increases the accessibility of binding sites and adsorption capacity by high microporosity and large surface area, that has been realized for the first time in a magnetic chitosan nanoparticle support. A fractional factorial design was utilized for screening the experimental parameters. The effective parameters were then optimized by Box–Behnken design. Under the optimized conditions, the developed method exhibited wide linear ranges of 5–500 μg L⁻¹ for plasma and urine and 10–500 μg L⁻¹ for breast milk samples with satisfactory recoveries in the range of 96.7–99.0%. Limit of detection and quantification of celecoxib were in the ranges 0.3–3.2 and 0.99–10.56, respectively. The enrichment factors were obtained in the ranges 64.5–66.0, while precisions were <3.7%.     

Application of magnetic graphene-based bucky gel as an efficient green sorbent for determination of mercury in fish and water samples

Research on Chemical Intermediates - In this article, a highly efficient method based on coupling magnetic solid-phase extraction and dispersive microsolid-phase extraction was proposed to...     

On topological centers induced by unitary representations

Archiv der Mathematik - Let $$(pi ,,H_pi )$$ be a unitary representation of a locally compact group G. The characterization of the minimality of the topological center induced by $$pi $$ is...