A bipolar high precision voltage-to-frequency converter is described. The circuit includes an input voltage-to-current conversion stage followed by a current-controlled multivibrator. The multivibrator trigger includes a window comparator with a limiter of the output voltage swing, and the timing capacitor discharge current is switched simultaneously with the window comparator bias. This allows...

A new Kinetic Spectrophotometic method for the Determination of trace amount Sulfacetamide Drug into real samples has been described based with silver nanoparticles starch-capped sensor, by sodium borohydride. The reaction is followed spectrophotometrically by measuring the decrease in the absorbance at 347.5 nm. 1.0×10-2 molL-1 silver nanoparticles starch-capped sensor, 2.0×10-3 mol L-1 sodium...

continuous exposure to high-energy ultrasonic waves depolymerises macromolecules in solutions and produces a permanent reduction in viscosity. different factors affect the efficiency of this ultrasonic depolymerisation. in this work ultrasonic degradation of one commercially important hydrogel based on acrylic acid and acrylamide was carried out in aqueous solution at room temperature (25oc). a...

An experimental design was applied to improve the reaction conditions for enzymatic synthesis of ampicillin from phenylglycine methyl ester (PGME) and 6-aminopenicillanic acid (6-APA), catalyzed by penicillin G acylase from E. coli immobilized on an agarose-glyoxyl derivative. The presence and magnitude of interactions between reaction variables were estimated using a 2 factorial design. A batc...

Axenic shoot culture of Mentha arvensis was established from young shoots of plants cultivated in a field. In the shoots cultured on Murashige-Skoog solid and liquid media for 3-4 weeks, pulegone was the main constituent in both cases, and the content of pulegone in liquid medium was much more than that on solid medium. The shoots cultured in the dark for 3 weeks produced only pulegone. However...

The study of dielectric relaxation properties in the binary mixture of polar molecules has been carried out at 25oC temperature for 11 different concentrations using time domain reflectometry technique. The dielectric properties of solute-solvent mixture in the microwave frequency range of 10MHz to 30GHz gives information about the formation of monomers and multimers as well as interaction betw...

In the present research, synthesis of new 2-(3-chlorobenzyl)-1H-benzimidazole derivatives bearing Nbenzylidene, 1,2,4-triazole and N-acylhydrazone moiety is investigated. These novel compounds have been tested for their antimicrobial effects against two of Gram-positive bacterial strains, namely Bacillus subtilis and Staphylococcus epidermidis, and four Gram-negative bacterial strains which wer...

A plastic membrane electrode for the determination of methacycline hydrochloride was fabricated based on the use of methacycline-tetraphenylborate as the electroactive substance, and dioctylphtalate as the plasticizing agent. It was found that the potential responses of the electrode were influenced by pH of the tested solution when pH>3. Under the condition of pH 2.6, the linear response range...