High-Performance Thin-Layer Chromatographic Assay of Metformin in Urine Using Ion-Pair Solid-Phase Extraction: Application for Bioavailability and Bioequivalence Study of New Microbeads Controlled Release Formulation

JPC – Journal of Planar Chromatography – Modern TLC - A sensitive high-performance thin-layer chromatographic (HPTLC) method was developed for the estimation of metformin in human...     

Design,Synthesis, and Evaluation of Some Novel Heterocycles Bearing Pyrazole Moiety as Potential Anticancer Agents

1,3‐Diphenylpyrazole‐4‐carboxylaldehyde and o‐hydroxyacetophenone were exploited as starting materials for the synthesis of novel substituted chalconated pyrazole derivative. The proclivity of this compound towards carbon and nitrogen nucleophiles such as malononitrile, diethyl malonate, ethyl cyanoacetate, ethyl acetoacetate, semicarbazide, thiosemicarbazide, and hydroxylamine has been investigated. The structures of all synthesized compounds were ascertained by analytical and spectral data. The antitumor activity of the target synthesized compounds was tested against a panel of two human tumor cell lines, namely, hepatocellular carcinoma (liver) HepG2 and mammary gland breast MCF‐7.     

Low Reynolds number axisymmetric turbulent boundary layer on a cylinder

In the present study, an axisymmetric turbulent boundary layer growing on a cylinder is investigated experimentally using hot wire anemometry. The combined effects of transverse curvature as well as low Reynolds number on the mean and turbulent flow quantities are studied. The measurements include the mean velocity, turbulence intensity, skewness and flatness factors in addition to wall shear stress. The results are presented separately for the near wall region and the outer region using dimensionless parameters suitable for each case. They are also compared with the results available in the open literature.The present investigation revealed that the mean velocity in near wall region is similar to other simple turbulent flows (flat plate boundary layer, pipe and channel flows); but it differs in the logarithmic and outer regions. Further, for dimensionless moments of higher orders, such as skewness and flatness factors, the main effects of the low Reynolds number and the transverse curvature are present in the near wall region as well as the outer region.     

Lie-group method of solution for steady two-dimensional boundary-layer stagnation-point flow towards a heated stretching sheet placed in a porous medium

The boundary-layer equations for two-dimensional steady flow of an incompressible, viscous fluid near a stagnation point at a heated stretching sheet placed in a porous medium are considered. We apply Lie-group method for determining symmetry reductions of partial differential equations. Lie-group method starts out with a general infinitesimal group of transformations under which the given partial differential equations are invariant. The determining equations are a set of linear differential equations, the solution of which gives the transformation function or the infinitesimals of the dependent and independent variables. After the group has been determined, a solution to the given partial differential equations may be found from the invariant surface condition such that its solution leads to similarity variables that reduce the number of independent variables of the system. The effect of the velocity parameter λ, which is the ratio of the external free stream velocity to the stretching surface velocity, permeability parameter of the porous medium k ₁, and Prandtl number Pr on the horizontal and transverse velocities, temperature profiles, surface heat flux and the wall shear stress, has been studied.     

UV-visible and infrared absorption spectra of Bi2O3 in lithium phosphate glasses and effect of gamma irradiation

Ultraviolet and visible absorption spectra of prepared undoped lithium phosphate glass and samples of the same nominal composition with additional Bi₂O₃ contents were measured before and after being subjected to gamma doses of 3 and 6 Mrad. The base undoped lithium phosphate glass exhibits strong charge transfer ultraviolet absorption bands, which are related to unavoidable presence of trace iron impurities within the raw materials for the preparation of this glass. Bi₂O₃-containing glasses show the extension of UV absorption beside the resolution of visible bands at 400, 450, and 700 nm with the increase of Bi₂O₃ content due the sharing of absorption of Bi³⁺ ions. Gamma irradiation of the base glass reveals extended induced bands; the UV bands are related to the conversion of some Fe²⁺ to Fe³⁺ through photochemical reactions during the irradiation process. The visible induced bands are related to the formation of positive hole centers from the host phosphate glass. Glasses containing Bi₂O₃ are observed to show some shielding behavior, which is attributed to the presence of heavy weight and large atomic number of Bi³⁺ ions. Infrared absorption spectral measurements of the base lithium phosphate glass show characteristic vibrational modes which are related to specific phosphate groups. The addition of Bi₂O₃ in measurable percent produces additional vibrational bands due to the introduction of Bi–O groups such as BiO₃ and BiO₆.     

Photoluminescence and photostability investigations of biocompatible semiconductor nanocrystals coated with glutathione using low laser power

Polybutylcyanoacrylate nanoparticles (PBCA NPs) are candidates for a drug delivery system, which can cross the blood–brain barrier (BBB). Because little is known about their toxicity, we exposed cells to PBCA NPs in vitro and in vivo and monitored their life and death assays. PBCA NPs were fabricated with different surfactants according to the mini-emulsion technique. Viabilities of HeLa and HEK293 cells after NP incubation were quantified by analysing cellular metabolic activity (MTT-test). We then repetitively injected i.v. rhodamine-labelled PBCA NP variations into rats and monitored the survival and morphology of retrogradely labelled neurons by in vivo confocal neuroimaging (ICON) for five weeks. To test for carrier-efficacy and safety, PBCA NPs loaded with Kyotorphin were injected in rats, and a hot plate test was used to quantify analgesic effects. In vitro, we found dose-dependent cell death which was, however, only detectable at very high doses and mainly seen in the cultures incubated with NPs fabricated with the tensids SDS and Tween. However, the in vivo experiments did not show any NP-induced neuronal death, even with particles which were toxic at high dose in vitro, i.e. NPs with Tween and SDS. The increased pain threshold at the hot plate test demonstrated that PBCA NPs are able to cross the BBB and thus comprise a useful tool for drug delivery into the central nervous system (CNS). Our findings showing that different nanoparticle formulations are non-toxic have important implications for the value of NP engineering approaches in medicine.     

Synthese et Etude Conformationnelle Par RMN (1H, 13C, 31P) et DFT des Cycloalcoxyphosphinallenes et des Hydrazones β-Cycloalcoxyphosphonatees

Abstract

The addition of hydrazine and its derivatives to cycloalkoxyphosphinallenes leads to β-(5,5-dialkyl-2-oxo-1,3,2-dioxaphosphoranyl)-hydrazones in good yields. The structure of the obtained compounds were elucidated by the NMR (¹H, ¹³C, ³¹P) spectroscopy and density functional theory (DFT) calculations at B3LYP/6-311++G (2d, 2p) level of theory.     

Pyrimidinthiones (Part I): Utility of 2-Thioxopyrimidin-6-(1H)ones as Ring Transformer in the Synthesis of Fused Bi- and Tri-Cyclic Heterocyclic Compounds and Their Potential Biological Activities

The pyrimidinethiones have wide biological and pharmaceutical activities, that have attracted considerable interest in recent years especially as antiviral inhibiting production of hepatitis B virus (HBV), and in vitro insulin-mimetic. Activity of the complexes of pyrimidinone derivatives evaluated from 50% inhibitory concentration promoted us to study the transformation of the 2-thioxopyrimidin-6(1H) ones to fused bi- and tri-cyclic heterocyclic compounds having the pyrimidine moieties and screening their biological activity.

The reactivity of 2-mercapto-4-aryl-5-cyanopyrimidin-6(1H)ones (1) towards alkylation by different mono and bifunctional halo-organic compounds has been investigated to give S-monoalkylated products 2, 7 and 9; S- and N-dialkylated products 3, 13 and 14. Treatment of 1 and/or 2 with hydrazine hydrate as a nitrogen nucleophile have been investigated to give 4, treatment of 4 with CS₂ and sodium nitrite in the presence of acetic acid (0°C) produced 1,2,4-triazolopyrimidin-5(1H)one derivatives (5)and tetrazolo[1,5-a]pyrimidin-5(1H)ones (6), respectively. Also cyclization of 7 and 9 gave [1,3]thiazolo[3,2-a]pyrimidin-5(1H)one and [1,3]thiazolo[3,2-a]pyrimidin-3,5-dione derivatives 8 and 10 respectively, treatment of 10 with aromatic aldehyde produces 11 which reacted with guanidine HCl to give pyrimido[4,5-d]thiazolo[3,2-a]pyrimidin-6(1H)one derivative 12. Reaction of 14 with o-phenylenediamine was investigated and gave [1,4]quinoxalino[2,3-b][1,3]thiazolo[3,2-a]pyrimidin-9(1H)one derivative 15.     

Burkholder theorem in Riesz spaces

The main purpose of this paper is to give a vector lattice version of a Theorem by Burkholder about convergence of martingales. The proof is based on a vector lattice analogue of Austin’s sample function theorem, proved recently by Grobler, Labuschagne and Marraffa and on a new characterization of elements of the sup-completion of a universally complete vector lattice do not belong to the space.