HPLC�CDAD Analysis of Hydrochlorothiazide and Irbesartan in Hypertensive Patients on Fixed-Dose Combination Therapy

Hydrochlorothiazide (HCTZ) and the angiotensin II type 1 receptor antagonist (ARB) irbesartan (IRBE) are well-known antihypertensive drugs, frequently administered as a low-dose combination in a single pill. In this work, a simple, sensitive, and selective high-performance liquid chromatographic (HPLC) method with diode-array detection was developed for simultaneous determination of HCTZ and IRBE levels in the plasma of hypertensive patients given a fixed combination of 12.5 mg HCTZ and 300 mg IRBE. Compounds were extracted from acidified plasma samples with 3 mL ethyl acetate, and eluted at 6 and 19 min from a C₄ column by elution with an acetonitrile?Cphosphate buffer (pH 3.6) mobile-phase gradient at a flow rate of 1 mL min^?1. The assay was linear over the ranges 2.5?C500 and 20?C4,000 ng mL^?1 for HCTZ and IRBE, respectively. Overall intra-assay and inter-assay variation were within acceptance limits. Limits of quantification were 2.5 and 20 ng mL^?1 for HCTZ and IRBE, respectively. Plasma samples remained stable for 12 h at room temperature, through three thaw?Cfreeze cycles, and for 2 and 7 months at ?20 °C. In hypertensive patients, residual concentrations were 22.3 ± 6.0 and 241.8 ± 39.0 ng mL^?1 for HCTZ and IRBE, respectively. There was no interference from other co-administered drugs. Despite the different physicochemical properties of HCTZ and IRBE, our method enables accurate measurement of both drugs for assessment of compliance by patients treated by fixed-dose combination therapy with HCTZ?CIRBE.     

The role of the Rashba coupling in spin-current of monolayer gapped graphene

In the current work, based on a semiclassical Boltzmann approach, we have investigatedthe influence of the Rashba spin-orbit coupling on spin-current of a single layer gappedgraphene. It was shown that the Rashba coupling plays a considerable role in thegeneration of the spin-current of vertical spins in mono-layer graphene. The behavior ofthe spin-current is determined by the density of impurities. It was also shown that thespin-current of the system could increase by increasing the Rashba coupling strength andband-gap of the graphene and the sign of the spin-current could be controlled by thedirection of the current-driving electric field.     

Structure of \mathrm {Gal}(\mathbb {k}_2^{(2)}/\mathbb {k}) for some fields \mathbb {k}=\mathbb {Q}(\sqrt{2p_1p_2},i) with \mathbf {C}l_2(\mathbb {k})\simeq (2, 2, 2)

Let \(p_1 \equiv p_2 \equiv 5\pmod 8\) be different primes. Put \(i=\sqrt{-1}\) and \(d=2p_1p_2\) , then the bicyclic biquadratic field \(\mathbb {k}=\mathbb {Q}(\sqrt{d},i)\) has an elementary abelian 2-class group of rank \(3\) . In this paper we determine the nilpotency class, the coclass, the generators and the structure of the non-abelian Galois group \(\mathrm {Gal}(\mathbb {k}_2^{(2)}/\mathbb {k})\) of the second Hilbert 2-class field \(\mathbb {k}_2^{(2)}\) of \(\mathbb {k}\) . We study the capitulation problem of the 2-classes of \(\mathbb {k}\) in its seven unramified quadratic extensions \(\mathbb {K}_i\) and in its seven unramified bicyclic biquadratic extensions \(\mathbb {L}_i\) .     

Versatile and Large-Scale Synthesis of Functional Dithiocarbamates in Water

Structural diversity is possible in direct access to functional dithiocarbamates based on a highly efficient and simple one-pot reaction of CS₂, amines, and alkyl halides in nearly quantitative yields in water.     

Dynamics of PEGylated–Dextran–Spermine Nanoparticles for Gene Delivery to Leukemic Cells

Leukemic cells are hard-to-transfect cell lines. Many transfection reagents which can provide high gene transfer efficiency in common adherent cell lines are not effective to transfect established blood cell lines or primary leukemic cells. This study aims to examine a new class of cationic polymer non-viral vector, PEGylated–dextran–spermine (PEG-D-SPM), to determine its ability to transfect the leukemic cells. Here, the optimal conditions of the complex preparation (PEG-D-SPM/plasmid DNA (pDNA)) were examined. Different weight-mixing (w/w) ratios of PEG-D-SPM/pDNA complex were prepared to obtain an ideal mixing ratio to protect encapsulated pDNA from DNase degradation and to determine the optimal transfection efficiency of the complex. Strong complexation between polymer and pDNA in agarose gel electrophoresis and protection of pDNA from DNase were detected at ratios from 25 to 15. Highest gene expression was detected at w/w ratio of 18 in HL60 and K562 cells. However, gene expression from both leukemic cell lines was lower than the control MCF-7 cells. The cytotoxicity of PEG-D-SPM/pDNA complex at the most optimal mixing ratios was tested in HL60 and K562 cells using MTS assay and the results showed that the PEG-D-SPM/pDNA complex had no cytotoxic effect on these cell lines. Spherical shape and nano-nature of PEG-D-SPM/pDNA complex at ratio 18 was observed using transmission electron microscopy. As PEG-D-SPM showed modest transfection efficiency in the leukemic cell lines, we conclude that further work is needed to improve the delivery efficiency of the PEG-D-SPM.     

Synthesis of New 1,4-Dihydropyridine Derivatives Containing Thiazolyl Substituents

A series of 4-[2-methyl (or aryl) thiazole-4-yl]-2,6-dimethyl-3,5-diacetyl (or dibenzoyl) 1,4-dihydropyridines were synthesized using a modified Hantzsch reaction involving the condensation of the corresponding aldehyde with acetyl acetone or benzoyl acetone. The preparation of the corresponding aldehydes (2-methylthiazole-4-carboxaldehyde and some 2-arylthiazole-4-carboxaldehydes) was achieved by a simplified protocol of the published synthesis.     

Trimethylsilyl Protection of Alcohols Over Phosphorus Pentoxide Supported on Silica Gel

Abstract

An eco-friendly and mild protocol for trimethylsilyl protection of alcohols over phosphorus pentoxide supported on silica gel using hexamethyldisilazane has been described. Solvent-free and ambient reaction conditions, easy workup, short reaction times, excellent yields, and reusability of the catalyst are the noticeable features of this methodology.

GRAPHICAL ABSTRACT     

NaBH4/Ac2O/DOWEX(R)50WX4: A Convenient System for Fast Preparation of gem‐Diacetates from Aldehydes

Reductive‐acylalation of aldehydes has been carried out by NaBH₄/Ac₂O/DOWEX(R)50WX4 system. A variety of aldehydes (1 mmol) have been reacted with Ac₂O (0.5 mL) and NaBH₄ (1 mmol) in the presence of DOWEX(R)50WX4 (0.5 g) for the preparation of their corresponding acylals within 1 min at room temperature with excellent yields of the products (90‐95%). Ketones do not react with this system.     

Kinetics Model of Destabilization of Oil Droplets in Oily Wastewater Emulsions

In this article, a mathematical model that accounts for the kinetics of flocculation and coalescence of emulsion drops was developed to quantify the kinetics of emulsion stability. The model is similar to that developed by Borwankar et al. in 1992 with corrections in coalescence rate constant and collision efficiency factor. It includes a term to describe efficiency of collisions. Also, the coalescence rate constant was defined as a function of the total number of particles that were present in the system at the moment. The model has four adjustable parameters, and nonlinear least square optimization is used to obtain the adjustable parameters. The obtained adjustable parameters by the model served as parameters that can be used to quantitatively evaluate the effectiveness of a set of different demulsifiers by measuring total numbers of drops versus time and by determining the adjustable parameters and comparing them. The results of the presented model and the model of Borwankar et al. were compared with experimental data. The results of the new model were in good agreement with experimental data and showed the model's ability for dispalying the behavior of droplets during the destabilization processes of emulsions.     

以方沸石负载Ni(II)催化剂修饰的电极电氧化甲醇Seyed Naser Azizi,Shahram Ghasemi,Neda Salek Gilani简

There is a high overvoltage in the oxidation of methanol in fuel cells, and so modified electrodes are used to decrease it. A modified electrode that used Ni(Ⅱ) loaded analcime zeolite to catalyze the electrooxidation of methanol in alkaline solution was proposed. Analcime zeolite was synthesized by hydrothermal synthesis, and Ni(Ⅱ) ions were incorporated into the analcime structure, which was then mixed with carbon paste to prepare modified electrode. The electrocatalytic oxidation of methanol on the surface of the modified electrode in alkaline solution was investigated by cyclic voltammetry and chronoamperometry. The effects of the scan rate of the potential, concentration of methanol, and amount of zeolite were investigated. The rate constant for the catalytic reaction of methanol was 6×10³ cm³ mol^-1 s^-1 from measurements using chronoamperometry. The proposed electrode significantly improved the electron transfer rate and decreased the overpotential for methanol oxidation.