Dynamics of orientation of adsorbed polar molecules in static electric and laser field

The rotational states of adsorbed polar molecule in the presence of static electric and laser field are investigated. In this study, we have taken two types of polar molecules, namely, one with large dipole moment and moderate rotational constant (LiCl), and the other with moderate dipole moment and large rotational constant (HBr). The adsorbed molecule is considered as rigid rotor in finite conical potential well. The eigenvalues are calculated by numerically solving the Schrödinger equation. We have shown that various properties of rotational states of the molecules are significantly influenced by the static electric field, laser field, conical potential well height and the hindrance angle. Also the use of two different polar molecules for the investigation is justified by the variation in various properties due to change in molecule.     

Development of extended release coevaporates and coprecipitates of promethazine HCl with acrylic polymers: formulation considerations

The present investigation studied a novel extended release system of promethazine hydrochloride (PHC) with acrylic polymers Eudragit RLPO and Eudragit RS100 in different weight ratios (1 : 1 and 1 : 5) using coevaporation and coprecipitation techniques. Solid dispersions were characterized by Fourier-transformed infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), Powder X-ray diffractometry (PXRD), Nuclear magnetic resonance (NMR), Scanning electron microscopy (SEM) as well as solubility and in vitro dissolution studies in 0.1 n HCl (pH 1.2), double distilled water and phosphate buffer (pH 7.4). Adsorption test from drug solution to solid polymers were also performed. Selected solid dispersion system was subjected to direct compression and compressed tablets were evaluated for in vitro dissolution studies. The progressive disappearance of drug peaks in thermotropic profiles of coevaporates were related to increasing amount of polymers while SEM studies suggested homogenous dispersion of drug in polymer. Eudragit RLPO had a greater adsorptive capacity than Eudragit RS100 and thus its coevaporates in 1 : 5 ratio exhibited higher dissolution rate with 91.90% drug release for 12 h. Among different formulations, tablets prepared by Eudragit RLPO coevaporates (1 : 5) displayed extended release of drug for 12 h with 90.87% release followed by zero order kinetics (r(2)=0.9808).     

Synthesis and biological activity of a cyclic hexapeptide from Dianthus superbus

Plant-originated cyclopolypeptide (XIII) was synthesized by coupling of dipeptide Boc-l-asn(bzh)-l-phe-OH and tetrapeptide gly-l-leu-l-ala-l-tyr-OMe followed by cyclization of a linear hexapeptide segment. Structure elucidation of XIII was done on basis of detailed spectral analysis including FTIR, ¹H NMR, ¹³C NMR, FAB MS and elemental analysis. From the results of pharmacological screening, it was concluded that XIII possesses high cytotoxic activity against DLA and EAC cell lines with CTC₅₀ values of 15.1 μM and 18.6 μM, and potent antimicrobial activity against pathogenic fungi C. albicans with MIC of 6 μg mL⁻¹. Moreover, XIII possesses moderate anthelmintic activity against earthworms M. konkanensis, P. corethruses, and Eudrilus sp. at 2 mg mL⁻¹ dose level.     

Synthesis,characterization and anticorrosive effect of 2-(phenoxy methyl)-5-phenyl-1, 3, 4-oxadiazole for mild steel in 1 M HCl: A combined experimental and computational demonstrations

Synthesis of 2-(phenoxymethyl)-5-phenyl-1, 3, 4-oxadiazole (2POM5PO) and corrosive inhibitive properties studied via weight loss (W.L.) measurement, electrochemical impedance spectroscopy, potentiodynamic polarisation measurements. Scanning Electron Microscope attached with Energy-dispersive X-ray spectroscopic methods were performed to notice morphological changes. These data were observed at a diversified dosage and temperatures the compound for 12 h s immersion of M.S. sheets in 1 M HCl electrolyte through W.L. measurements, furthermore inferred that the inhibition efficiency expanded with slow augmentations in the dosage of each moiety. The maximum inhibitory efficiency was determined which is 88.41% at 300 ppm and 298 K. E.I.S. studies demonstrated that charge transfer resistance increased on concentration increment, confirming each molecule's prohibitive attitude. Potentiodynamic polarisation plots revealed that the compounds displayed mixed type behavior. The Langmuir adsorption model was suited best, proving moiety act as a good corrosion controlling compound in 1 M Hydrochloric acid media. Computational study shows a good correlation with experimental results.     

Toward the synthesis and biological evaluation of hirsutide

Abstract  

The present investigation deals with the synthesis of a N-methylated cyclotetrapeptide, hirsutide (2), by coupling of the dipeptide units Boc-l-phenylalanyl-l-N-methylphenylalanine-OH and l-valyl-l-N-methylphenylalanine-OMe followed by cyclization of the linear tetrapeptide fragment. The chemical structure was established on the basis of analytical as well as spectroscopic data. The newly synthesized cyclic peptide was subjected to pharmacological screening and found to be highly potent against the gram-negative bacteria Pseudomonas aeruginosa and Klebsiella pneumoniae at 6 μg cm⁻³. In addition, potent antihelmintic activity against the earthworms Megascoplex konkanensis and Pontoscotex corethruses at 1 and 2 mg cm⁻³, and potent cytotoxic activity against Dalton’s lymphoma ascites and Ehrlich’s ascites carcinoma cell lines with IC₅₀ values of 14 and 22 μM were also observed. Studies revealed that the pentafluorophenyl ester method employing a catalytic amount of N-methylmorpholine proved to be better for cyclization of the linear tetrapeptide unit.     

A technique for frequency stabilization of an internal mirror He-Ne laser

A technique for frequency stabilization of an internal mirror He-Ne laser using phase sensitive detection without cavity length modulation is suggested. The orthogonally plane polarized modes are separated and then convered into two photoelectric signals using two photodetectors. The photoelectric signals are switched alternately so as to generate a square wave, whose amplitude is proportional to the intensity difference between the two orthogonal polarizations. A lock-in amplifier is used to detect this square wave, with the switching frequency as reference. The phase detected signal is used for thermal stabilization of the laser. The frequency stability of 5 × 10⁻⁹ was obtained with an integration time of 1 s.     

Reflection of modified Korteweg-de Vries solitons in a plasmahaving negative ions

The variable coefficient modified Korteweg-de Vries (mKdV) equations for incident and reflected solitons are derived and solved to study the reflection of compressive and rarefactive ion acoustic solitons at the critical density in an inhomogeneous negative ion plasma. The polarity of the incident compressive and rarefactive solitons is not altered during the reflection process. Increasing the density gradient reinforces the reflection of both compressive and rarefactive mKdV solitons, whereas enhancement of the unperturbed plasma density weakens the reflection