A new phthalic acid ester from Ajuga bracteosa

A new phthalic acid ester 1,2-benzenedicarboxylic acid bis(2S-methyl heptyl) ester (1) was isolated from the hexane extract of the whole plant of Ajuga bracteosa. In addition, chloroform and methanol extracts yielded neo-clerodane diterpene ajugarin-I and two iridoid glycosides, reptoside and 8-O-acetyl harpagide. The structures of all the compounds were confirmed by extensive spectroscopic analysis. From the two oily fractions nine and six volatile constituents respectively were identified by GCMS. Linalyl acetate was found to be common in both the oil fractions. This plant is a new source of linalyl acetate, a valuable perfumery compound.     

Microwave- and ultrasound-assisted extraction of vanillin and its quantification by high-performance liquid chromatography in Vanilla planifolia

Microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE) and conventional extraction of vanillin and its quantification by HPLC in pods of Vanilla planifolia is described. A range of nonpolar to polar solvents were used for the extraction of vanillin employing MAE, UAE and conventional methods. Various extraction parameters such as nature of the solvent, solvent volume, time of irradiation, microwave and ultrasound energy inputs were optimized. HPLC was performed on RP ODS column (4.6 mm ID x 250 mm, 5 microm, Waters), a photodiode array detector (Waters 2996) using gradient solvent system of ACN and ortho-phosphoric acid in water (0.001:99.999 v/v) at 25 degrees C. Regression equation revealed a linear relationship (r2 > 0.9998) between the mass of vanillin injected and the peak areas. The detection limit (S/N = 3) and limit of quantification (S/N = 10) were 0.65 and 1.2 microg/g, respectively. Recovery was achieved in the range 98.5-99.6% for vanillin. Maximum yield of vanilla extract (29.81, 29.068 and 14.31% by conventional extraction, MAE and UAE, respectively) was found in a mixture of ethanol/water (40:60 v/v). Dehydrated ethanolic extract showed the highest amount of vanillin (1.8, 1.25 and 0.99% by MAE, conventional extraction and UAE, respectively).     

Chaos based multiple image encryption using multiple canonical transforms

We propose a new method for multiple image encryption using linear canonical transforms and chaotic maps. Three linear canonical transforms and three chaotic maps are used in the proposed technique. The three linear canonical transforms that have been used are the fractional Fourier transform, the extended fractional Fourier transform and the Fresnel transform. The three chaotic maps that have been used are the tent map, the Kaplan-Yorke map and the Ikeda map. These chaotic maps are used to generate the random phase masks and these random phase masks are known as chaotic random phase masks. The mean square error and the signal to noise ratio have been calculated. Robustness of the proposed technique to blind decryption has been evaluated. Optical implementation of the technique has been proposed. Experimental and simulations results are presented to verify the validity of the proposed technique.     

Digital image watermarking using gyrator transform and chaotic maps

We propose a new method for digital image watermarking using gyrator transform and chaotic maps. Four chaotic maps have been used in the proposed technique. The four chaotic maps that have been used are the logistic map, the tent map, the Kaplan-Yorke map and the Ikeda map. These chaotic maps are used to generate the random phase masks and these random phase masks are known as chaotic random phase masks. A new technique has been proposed to generate the single chaotic random phase mask by using two chaotic maps together with different seed values. The watermark encoding method in the proposed technique is based on the double random phase encoding method. The gyrator transform and two chaotic random phase masks are used to encode the input image. The mean square error, the peak signal-to-noise ratio and the bit error rate have been calculated. Robustness of the proposed technique has been evaluated in terms of the chaotic maps, the number of the chaotic maps used to generate the CRPM, the rotation angle of the gyrator transform and the seed values of the chaotic random phase masks. Optical implementation of the technique has been proposed. The computer simulations are presented to verify the validity of the proposed technique.     

DEVELOPMENT OF A CATALYST FOR SOLUTION OF POLY(VINYL ALCOHOL) IN NON-AQUEOUS MEDIUM

Chloro ethane dimethyl sulfoxide,C_2H_5Cl·DMSO(ECI·DMSO)was prepared by interaction of acrylic acid with conc.Hydrochloric acid in dimethyl sulfoxide(DMSO)and subsequent decarboxylation with H_2O_2 solution.The formation of the compound was confirmed by spectral and analytical methods;the molecular weight was determined by cryoscopic method.The solubility of poly(vinyl alcohol)(PVA)in different solvents or mixed solvents at 40℃,50℃and 60℃temperature in the presence of 0.01% of EC1·-DMSO was determined.It...     

Studies on Structural,Morphological and Optical Properties of Chemically Deposited CdS<Subscript>1-x</Subscript>Se<Subscript>x</Subscript> Thin Films

The thin films of CdS_1-xSe_x were successfully deposited over glass substrates by chemical bath deposition technique. Cadmium acetate, thiourea and sodium selenosulfate were used as source materials for Cd²⁺, S^2? and Se^2? ions, while 2-mercaptoethanol was used as capping agent. The various deposition conditions such as precursor concentration, deposition temperature, pH and deposition time were optimized for the deposition of CdS_1-xSe_x thin films of good quality and the films were annealed at 200° and 300 °C. The structural, morphological, chemical and optical properties were examined by various characterization techniques and discussed in detail. The optical band gap of CdS_1-xSe_x thin film samples were estimated and found in the range from 2.11 to 1.79 eV for as-deposited and annealed thin films.     

Elastomeric polyurethanes modified with geminal bisphosphonate groups

Three types of elastomeric segmented polyurethanes represented by a polyether‐urethane, a polyurethane‐urea, and a polycarbonate‐urethane were introduced into a modified low‐temperature variant of base‐induced N‐alkylation of urethane hard segments with an excess of 1,6‐dibromohexane in N,N′‐dimethylacetamide (DMAc), resulting in the modification of polymers with 0.08–0.26 mmol/g of pendant 6‐bromohexyl groups. Either lithium diisopropylamide (LDA) or sodium hydride was used to initiate the reaction, although LDA was found to be more suitable for the bromoalkylation. Selected bromoalkylated polyurethanes of all three types were reacted with thiol‐containing bisphosphonates, to yield the polymers modified with 0.08–0.12 mmol/g of geminal nonesterified covalently attached bisphosphonate groups. Two thiol‐containing geminal bisphosphonates used in the modifications were prepared via reactions of nucleophilic addition to vinylidene‐bisphosphonic acid. All three types of polyurethanes were found equally suitable for the modifications. The bisphosphonate‐modified polyurethanes with nonmetallic cations on the bisphosphonate groups remain soluble in the solvents suitable for the dissolution of nonmodified polymers and can be processed into films by solvent casting. After the exchange of nonmetallic cations to sodium, the polymers become insoluble in any solvent, probably as a result of the intermolecular coordination of bisphosphonate groups with the metal cations. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 105–116, 2001     

Ionic liquid‐based dispersive liquid–liquid microextraction followed by RP‐HPLC determination of saquinavir in rat serum: application to pharmacokinetics

An ionic liquid‐based dispersive liquid–liquid microextraction followed by RP‐HPLC determination of the most commonly prescribed protease inhibitor, saquinavir, in rat plasma was developed and validated. The effects of different ionic liquids, dispersive solvents, extractant/disperser ratio and salt concentration on sample recovery and enrichment were studied. Among the ionic liquids investigated, 1‐butyl‐3‐methylimidazolium hexafluorophosphate was found to be most effective for extraction of saquinavir from rat serum. The recovery was found to be 95% at an extractant/disperser ratio of 0.43 using 1‐butyl‐3‐methylimidazolium hexafluorophosphate and methanol as extraction and dispersive solvents. The recovery was further enhanced to 99.5% by addition of 5.0% NaCl. A threefold enhancement in detection and quantification limits was achieved, at 0.01 and 0.03 µg/mL, compared with the conventional protein precipitation method. A linear relationship was observed in the range of 0.035–10.0 µg/mL with a correlation coefficient (r²) of 0.9996. The method was validated and applied to study pharmacokinetics of saquinavir in rat serum. Copyright © 2014 John Wiley & Sons, Ltd.