To Be or Not To Be a Molecular Ion: The Role of the Solvent in Photoionization of Arginine.

Application of photoionization mass spectroscopy, a technique capable of assessing protonation states in complex molecules in the gas phase, is challenging for arginine due to its fragility. We report photoionization efficiencies in the valence region of aqueous aerosol particles produced from arginine solutions under various pH and vaporization conditions. By using ab initio calculations, we investigate the stability of different conformers. Our results show that neutral arginine fragments upon ionization in the gas phase but solvation stabilizes the molecular ion, resulting in different photoionization dynamics. We also report the valence-band photoelectron spectra of the aerosol solutions obtained at different pH values

Solving multicollinearity problem of gross domestic product using ridge regression method

This study is dedicated to solving multicollinearity problem for the general linear model by using Ridge regression method. The basic formulation of this method and suggested forms for Ridge parameter is applied to the Gross Domestic Product data in Iraq. This data has normal distribution. The best linear regression model is obtained after solving multicollinearity problem with the suggesting of value

DESIGN AND EVALUATION OF DOMPERIDONE SUBLINGUAL TABLETS

Objective: The aim of this work was to enhance the bioavailability of poorly soluble, anti-emetic drug; domperidone (DMP) having a poor oral bioavailability (13-17%) due to extensive first pass metabolism. The goal of this study was achieved through solubilization of DMP using solid dispersion technology followed by incorporation of solid dispersions into sublingual tablets to bypass pre-systemic metabolism.Methods: Solid dispersions of DMP with Pluronic F-68 were prepared in different weight ratios by fusion method and they were evaluated for their in vitro dissolution rate to select the best ratio for final formulation. Then, solid dispersions were formulated into sublingual tablets in combination with various soluble excipients. Sublingual tablets were prepared by direct compression technique and evaluated for their physical properties, in vitro dissolution rate and kinetics of drug release. The best formulae were selected for in vivo studies in rabbits in comparison with marketed oral tablets; Motinorm®.Results: Solid dispersions of DMP with Pluronic F-68 in a weight ratio of 1:7 (w/w) showed the highest dissolution rate and were selected for sublingual tablets formulation. Sublingual tablets formulae S16 (containing Fructose and 10% w/w Ac-Di-Sol) and S20 (containing Fructose and 10% w/w Explotab) showed the best results and were selected for in vivo studies in rabbits. The selected formulae showed marked enhancement of DMP bioavailability compared with the commercial oral tablets; Motinorm®, with relative bioavailability values of 432.49±10.13% and 409.32±11.59 % for S16 and S20, respectively.Conclusion: The results confirmed that sublingual tablets were an effective tool for DMP delivery with marked enhancement of bioavailability.Keywords: Domperidone, Solubility, Solid dispersions, Sublingual tablets, First-pass metabolism, Bioavailabilit

Comparative analysis of exhaust gases obtained in S.I and C.I of an internal combustion engine

This paper is aimed at analyzing, determining and comparing the composition of exhaust gases of automobile ICE through experimental determination of the exhaust gas values at different loads and speeds of both engines; and determination of the effect of engine speeds and loads on exhaust emissions of both engines.ICE which could be spark ignition (S.I) or compression ignition (C.I) engine is one of the building blocks of modern civilization. In light of this, an effective engine should be able to contribute immensely to a safe environment. Numerous factors like fuel economy, power and torque, reliability, pollution, safety and cost are necessary in determining and comparing the effectiveness of the engines. This paper identifies, examines and compares the rate of incombustible particles present in the engines (S.I and C.I) at varying loading and speed conditions via exhaust gas detector. Post-hoc analysis was carried out using SPSS. It was discovered that CO and HC are the most dangerous incombustible particles present in engines and also the incombustible rate is more pronounced in C.I than S.I engine, which confirmed that S.I. engine is far better in terms of pollution reduction. Probable recommendations were later made.Self-sponsore

Scattering states of a particle, with position-dependent mass, in a PT{\cal{PT}} symmetric heterojunction

The study of a particle with position-dependent effective mass (pdem), within a double heterojunction is extended into the complex domain --- when the region within the heterojunctions is described by a non Hermitian ${\cal{PT}}$ symmetric potential. After obtaining the exact analytical solutions, the reflection and transmission coefficients are calculated, and plotted as a function of the energy. It is observed that at least two of the characteristic features of non Hermitian ${\cal{PT}}$ symmetric systems --- viz., left / right asymmetry and anomalous behaviour at spectral singularity, are preserved even in the presence of pdem. The possibility of charge conservation is also discussed.Comment: 12 pages, including 6 figures; Journal of Physics A : Math. Theor. (2012

Stevens Johnson syndrome in Pakistan: a ten-year survey

Objective: A pre-tested questionnaire-based, retrospective study to highlight the causative factors, mode of presentation, complications and outcome of patients with Stevens Johnson syndrome.SETTING: Aga Khan University Hospital over a 10 year period.Methods: All case records with a diagnosis of Steven Johnson Syndrome in the period 1990 to 2000 were retrospectively reviewed. Data was retrieved on a comprehensive questionnaire. The demographic variatbles and drugs taken within the previous 21 days were noted. Date analysis was done by Epi-Info Version 6.0.Results: Of the 101 studied patient files, the most common offender was found to be the Penicillins as a group and Sulfadoxine-Pyrimethamine (Fansidar) when considering all drugs individually. Most common complications included electrolyte disturbances (13.9%) and congestive heart failure (6.9%). Mortality rate was high at 10.1%.CONCLUSION: SJS was found to be a rare condition but having a mortality rate of 10.1%. As it can be induced by a large number of drugs, caution should be practiced while prescribing

Hibiscus acid from hibiscus sabdariffa (malvaceae) has a vasorelaxant effect on the rat aorta

Hibiscus sabdariffa (Malvaceae) is a plant that is widely recognised for its antihypertensive properties; however the constituent(s) responsible for this biological activity are presently unknown. The aim of this study was to identify the potential compounds that are responsible for the vasorelaxant activity of H. sabdariffa. Thereafter, the mechanisms involved in producing the vasorelaxation were investigated. The plant was extracted consecutively with hexane, ethyl acetate and methanol. The methanolic extract was subjected to bioassay-guided fractionation in order to isolate pure compounds that possessed vasorelaxant activity. The vascular effects of the pure compounds were studied on the rat aorta in vitro using myography techniques. Hibiscus acid produced a concentration-dependent relaxation of the rat aorta pre-contracted with either phenylephrine (3 μM) or KCl (60 mM), irrespective of the presence of the endothelium. When the tissue was pre-contracted with phenylephrine, the concentration required to produce 50% relaxation (IC50), was 0.09 ± 0.01 mg/ml. Hibiscus acid had no effect on the phasic contraction induced by phenylephrine in Ca2+-free physiological solution; but it did affect the component of the contraction that is due to Ca2+ influx. In parallel studies, garcinia acid, a diastereoisomer of hibiscus acid, was found to have an almost identical vasorelaxant effect. The vasorelaxant action of both compounds is most likely due to the inhibition of Ca2+ influx via voltage-dependent Ca2+ channels