Double-charged ionic liquid-functionalized layered double hydroxide nanomaterial as a new fiber coating for solid-phase microextraction of phenols

Double-charged diazabicyclo[2.2.2]octane (DABCO) was immobilized on the inner surface of a nanomaterial composed of the layered double hydroxides (LDHs) of Zn(II) and Cr(III). The resulting material was characterized by SEM, FT-IR and XRD techniques. This novel nanocomposite has been used as a highly porous fiber coating for solid-phase microextraction (SPME) of phenol and various chloro-, nitro- and aminophenols. The LDH nanocomposite was deposited on a stainless steel wire and then evaluated with respect to the extraction of phenolic compounds from water samples. The effects of temperature, extraction time, ionic strength, stirring rate, pH, and desorption temperature and time on the extraction were optimized. The compounds were then separated and quantified by GC-MS. Under optimum conditions, the repeatability for a single fiber (for n = 3 and expressed as the relative standard deviation) is between 2.3 and 7.2 %. The detection limits are between 0.02 and 6.3 pg mL⁻¹. The method is simple, rapid, and inexpensive. The fiber is thermally stable and its use gives high recoveries.

Double-charged diazabicyclo[2.2.2]octane (DABCO) was immobilized on the inner surface of a nanomaterial composed of the layered double hydroxides (LDHs) of Zn(II) and Cr(III). This novel nanocomposite has been used as a highly porous fiber coating for solid-phase microextraction (SPME) of phenol and various chloro-, nitro- and aminophenols.

     

Modified nanoporous silicas for oral delivery of the water insoluble organotin compound: loading and release of methylphenyltin dichloride as an anti-tumor drug model

Different nanoporous silica materials, MCM-41, MCM-48 and SBA-15, were modified by pyridine and their applications for oral drug delivery system were evaluated. These pyridine functionalized nanoporous silicas were loaded with a water insoluble diorganotin(IV) dichloride complex as an antitumor drug model and its release from them were investigated by changing pH. An efficient pH-responsive carrier system was constructed by coordination of the pyridine group in modified nonoporous materials to tin complex. In vitro, releasing of loaded tin complex was studied in three different kinds of fluids, including a simulated gastric medium and a simulated body fluid. The loading and releasing of the diorganotin(IV) dichloride from various modified nanoporous silicas and also a non-porous silica (SiO₂) were investigated, and the results were compared. In addition, the effect of some factors such as pH, time of loading and releasing were investigated through this study.     

Synthesis of flavanones, azaflavanones, and thioflavanones catalyzed by PMA-SiO2 as a mild, efficient, and reusable catalyst

Abstract  

Cyclization of a variety of chalcones to flavanones catalyzed by 1 mol% phosphomolybdic acid (PMA) supported on silica as a mild, efficient, and reusable catalyst was carried out in high yields. PMA-SiO₂ is an efficient, inexpensive, and green catalyst which gave high conversion yields and could be recycled up to three times without significant loss in activity.     

硅胶键合的N-丙基三亚乙基四胺氨基磺酸作为可回收固体酸催化剂催化合成2-氨基-4,6-二芳基烟腈(英文)

A simple and efficient procedure for the preparation of silica-bound N-propyl triethylenetetramine sulfamic acid(SBPTETSA) by the reaction of silica-bound N-propyl triethylenetetramine(SBPTET) with chlorosulfonic acid in chloroform is described.Silica-bound N-propyl triethylenetetramine sulfamic acid was employed as a recyclable catalyst for the synthesis of 2-amino-4,6-diarylnicotinonitriles from the multi-component reaction of an acetophenone derivative,an aromatic aldehyde,malononitrile,and ammonium acetate under solvent-free conditions at 100 °C.The heterogeneous catalyst was recycled for five consecutive runs in the optimized multi-component reaction of 4-chloroacetophenone,4-chloroenzaldehyde,malononitrile,and ammonium acetate without significant loses to its catalytic activity.     

A Modified Synthesis of Some Novel Polycyclic Aromatic Phenazines and Quinoxalines by Using the Tungstate Sulfuric Acid (TSA) as a Reusable Catalyst under Solvent‐free Conditions

Considering the synthesis of new compounds, we developed heterocyclic chemistry. We also helped to improve the classical synthetic route for the synthesis of quinoxalines and phenazines through implement in terms of solvent‐free reaction. For the condensation of 1,2‐dicarbonyls and o‐phenylenediamines under solvent‐free conditions at room temperature, tungstate sulfuric acid (TSA) was found to be an efficient and reusable reagent. The high yield of the pure products and simple preparation of the catalyst have allowed the synthesis of several phenazines and quinoxalines using this methodology.     

The effects of olibanum administered to methimazole-treated dams during lactation on learning and memory of offspring rats

The effect of olibanum administered during lactation to methimazole-treated dams on the learning of offspring was evaluated. The animals were treated for 60 days from the first day of lactation period: group 1--tap water, group 2-0.03% methimazole and groups 3 and 4-0.03% methimazole with 0.25% or 0.125% olibanum, respectively. The serum thyroxin level in the offspring of group 2 was significantly lower than that of group 1. However, there was no difference compared to groups 3 and 4. In a Morris water maze, the distance and time latency to reach the platform in offspring of group 2 was significantly higher than groups 1, 3 and 4. In probe trial, the time spent in target quadrant (Q?) by offspring of group 2 was lower than groups 1,?3 and 4. It is suggested that impaired learning and memory in the offspring of hypothyroid rats may be prevented by olibanum.     

Antibacterial activity and comparison of the volatile constituents obtained by several extraction methods from the flowers, stems and leaves of Astrodaucus orientalis

The oils of the flowers, stems and leaves of Astrodaucus orientalis L. were separately extracted using hydrodistillation (HD), head-space solid-phase microextraction (HS-SPME) and microwave assisted head-space solid-phase microextraction (MA-HS-SPME). The volatile constituents were analyzed by GC and GC/MS. Temperature and time of extraction, microwave power and exposure time of extraction were optimized. Polydimethylsiloxane (PDMS) fiber was used as the solid phase for SPME methods. The main constituents of the flower, stem and leaf oils isolated by HD, HS-SPME and MA-HS-SPME are as follows, respectively: beta-pinene (20.5%, 13.9% and 30.4%), alpha-thujene (8.7%, 16.2% and 10.9%) and alpha-pinene (7.6%, 14.3% and 10.9%) for the flowers, sabinene (11.8%, 32.3% and 11.8%), alpha-pinene (8.7%, 28.8% and 6.1%) and p-mycrene (2.5%, 12% and 8.5%) for the stem, and alpha-pinene (9.4%, 37.1% and 22.5%), sabinene (13.5%, 26.3% and 23.5%), beta-pinene (6.3%, 9.8% and 10%) and p-mycrene (3.2%, 2.5% and 15.6%) for the leaf. The minimum inhibitory concentrations (MIC) were determined for all essential oils obtained by HD against both Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria using the agar dilution method. These oils showed the good activities against the both bacteria (0.5 - 1.5 mg/mL).     

Flow invariance for solutions to nonlinear nonautonomous partial differential delay equations

We investigate the problem of existence and flow invariance of mild solutions to nonautonomous partial differential delay equations , t?s, us=φ, where B(t) is a family of nonlinear multivalued, α-accretive operators with D(B(t)) possibly depending on t, and the operators F(t,.) being defined—and Lipschitz continuous—possibly only on “thin” subsets of the initial history space E. The results are applied to population dynamics models. We also study the asymptotic behavior of solutions to this equation. Our analysis will be based on the evolution operator associated to the equation in the initial history space E.     

Thermodynamic and kinetic studies of As2O3 toxicological effects on human insulin in generation diabetes mellitus

The interaction of arsenic trioxide with human insulin was investigated by circular dichroism (CD), cyclic voltammetry and electrophoresis techniques. The interfacial behavior of insulin in presence of As₂O₃ onto the Ag electrode surface was studied at 310 K in phosphate buffer solution (PBS). According to Far-UV CD spectroscopy results, As₂O₃ caused to decrease in structural compactness and variety of alpha helix into beta structures. Near-UV CD indicated that As₂O₃ dissociates disulfide linkage in insulin structure. The kinetic parameters, including charge-transfer coefficient and apparent heterogeneous electron transfer rate constant were also determined. The thermodynamic parameters of insulin denaturation in presence of arsenic trioxide were calculated and reported. The obtained results indicated strong adsorption of insulin in presence of arsenic trioxide onto the Ag surface via chemisorptions.