In vitro antioxidant activities of five β-carboline alkaloids,molecular docking,and dynamic simulations

Structural Chemistry - Experimental and computational studies were performed to determine the antioxidant activities of harmine, harmaline, harmalol, harmane, and...     

Normal ordering problem and the extensions of the Stirling grammar

The purpose of this paper is to investigate the connection between context-free grammars and normal ordered problem, and then to explore various extensions of the Stirling grammar. We present grammatical characterizations of several well known combinatorial sequences, including the generalized Stirling numbers of the second kind related to the normal ordered problem and the r-Dowling polynomials. Also, possible avenues for future research are described.     

Investigation of Solution p<Emphasis Type="Italic">K</Emphasis><Subscript>a</Subscript> and Thermodynamic Values of Lamivudine and Pefloxacin Drugs by Ab initio and DFT Methods

In this work we investigate the thermodynamic properties and pK_a value of lamivudine and pefloxacin drugs, in aqueous solutions, by ab initio and density functional theory (DFT) methods at different temperatures. Molecular structures and solute–solvent effects of the anions, cations, and neutral molecules of lamivudine and pefloxacin were studied by the polarizable continuum model (PCM). The calculation was done at the DFT-B3LYP/6-31+G(d) level of theory using Tomasi’s method to analyze the formation of intermolecular hydrogen bonds (IHB) in aqueous solution. The pK_a1 values of lamivudine and pK_a2 values of pefloxacin increase with temperature increase. In contrast, the pK_a1 values of pefloxacin decrease when the temperature increases. Further, the thermodynamic properties of the ionization processes (?H, ?S and ?G) of the drugs in aqueous solution were determined and discussed. The results of this work are in good agreement with the literature data at 298.15 K.     

Determination of gold in water samples using electromembrane extraction

In this work, an electromembrane extraction (EME) technique was used for the extraction and determination of gold from water samples prior to UV-Vis spectrophotometry. An artificial neural network (ANN) combined with imperialist competitive algorithm (ICA) has been applied to optimize the EME. The effective parameters including pH of acceptor phase, extraction time (t), volume of sample solution (V), stirring rate (S), and voltage (E) were chosen as input variables and the extraction recovery of gold was considered as output variable. The mean of squared error (i.e., 0.0009) and determination coefficient (i.e., 0.9821) were applied to estimate the performance of the ANN model. The limit of detection was 4.5?µg L^?1 (S/N?=?3) on the optimized variables. The intra- and interday precisions (%) were found to be 6.7% and 2.6%, respectively. This technique was then applied for analysis of gold from environment water samples.     

Chemistry of phosphorus ylides: Part 45 synthesis of phosphoranylidene,thietane, azetidine and thiazinane derivatives as potent chemo preventative agents

Reactions of nucleophilic active phosphacumulenes with iso(thio)cyanate compounds were performed. The reaction products depend on the nature of the reagent, substrate and the condition of the reaction used. New heterocyclic 4-membered or 6-membered sulfur and nitrogen compounds such as phosphoranylidene thietane, azetidine and thiazinane were obtained. On the other hand, the stable phosphonium ylides with the iso(thio)cyanate afforded phosphoranylidene thiocarbamoyl derivatives. Possible reaction mechanisms are considered and the structural assignments are based on compatible analytical and spectroscopic data.     

The effect of methyl jasmonate and light irradiation treatments on the stilbenoid biosynthetic pathway in Vitis vinifera cell suspension cultures

Grape stilbenes are a well-known family of plant polyphenolics that have been confirmed to have many biological activities in relation to health benefits. In the present study, we investigated the effect of methyl jasmonate (MeJA) elicitor at four different concentrations (25, 50, 100 and 200 μM) in combination or not with high-level light irradiation (10,000 LUX) on a cell line obtained from the pulp of Vitis vinifera cv. Shahani. Our results showed that the stilbene synthesis pathway is inhibited by high-light conditions. A concentration of 50 μM MeJA was optimum for efficient production and high accumulation of total phenolics and total flavonoids as well as total stilbenoids. Furthermore, we showed that there is a significant negative correlation between the production of these metabolites and cell growth. These data provide valuable information for the future scale-up of cell cultures for the production of these very high value compounds in bioreactor system.     

On construction ofk-wise independent random variables

A 0–1probability space is a probability space (, 2,P), where the sample space -{0, 1} ⁿ for somen. A probability space isk-wise independent if, whenY _i is defined to be theith coordinate or the randomn-vector, then any subset ofk of theY _i 's is (mutually) independent, and it is said to be a probability spacefor p ₁,p ₂, ...,p _n ifP[Y _i =1]=p _i .We study constructions ofk-wise independent 0–1 probability spaces in which thep _i 's are arbitrary. It was known that for anyp ₁,p ₂, ...,p _n , ak-wise independent probability space of size always exists. We prove that for somep ₁,p ₂, ...,p _n [0,1],m(n,k) is a lower bound on the size of anyk-wise independent 0–1 probability space. For each fixedk, we prove that everyk-wise independent 0–1 probability space when eachp _i =k/n has size (n _k ). For a very large degree of independence —k=[n], for >1/2- and allp _i =1/2, we prove a lower bound on the size of . We also give explicit constructions ofk-wise independent 0–1 probability spaces.This author was supported in part by NSF grant CCR 9107349.This research was supported in part by the Israel Science Foundation administered by the lsrael Academy of Science and Humanities and by a grant of the Israeli Ministry of Science and Technology.