Adsorptive immobilization of submitochondrial particles on concanavalin a sepharose-4b

Submitochondrial particles (SMPs) prepared from beef liver mitochondria were immobilized on concanavalin A Sepharose-4B (Con A Sepharose). The process of immobilization was optimized by choosing an appropriate buffer system containing Mn²⁺ and Ca²⁺. Adsorption of SMPs on Con A-Sepharose was found to be a reversible process, nonelectrostatic in nature, and responsive to the presence of methyl α-d-glucopyranose and α-d-mannose. The involvement of membrane glycoproteins in the adsorption process was thus demonstrated. Further analysis of the data obtained on competition of binding by sugar molecules provided competition constants reflecting the potency of inhibition by each individual carbohydrate. Positive-cooperative interactions for binding to the matrix were observed especially at high concentrations of SMPs. The immobilized preparations were used successfully in continuous catalytic transformations involving succinate-cytochrome c reductase (SCR) an enzyme complex of the inner-mitochondrial membrane. Best results were obtained when such operations were carried out at 37?C.     

Effect of using mixed ion-pairs on PVC-membrane electrodes for ephedrine

Mixed ion-pairs based on the use of ephedrinium (EPH)-TPB plus EPH-reineckate (II) and phenylephrine-TPB plus EPH-reineckate (III) were tried for use in plastic membranes. The results were compared to those of an EPH-reineckate (I) single ion-pair electrode. The Nernstian slopes were 50, 49 and 55 mV decade^–1 for membranes I, II and III, respectively. The linear concentration ranges were 10^–5–10^–1, 4.0 × 10^–5–10^–1 and 6.3 ×^–5–10^–1 M ephedrine. The detection limits were 4 ×^–6,10^–5 and 1.2 × 10^–5 M ephedrine for membranes I, II and III, respectively. The pH ranges were 4–9, 3–9 and 2–8 for I, II and III-membranes, respectively. Selectivity coefficient values for membrane II were better than those for membranes I and III. The effects of increasing KC1 concentration and temperature changes were explained for the three electrodes. The isothermal temperature coefficients were 0.00145, 0.0007 and 0.00055 V/ °C for electrodes I, II and III. Electrode III was applied for the determination of ephedrine in its pharmeaceutical preparations with an overall relative standard deviation range of 1.3–2.4% and an overall mean recovery value of 98.1%.     

One-pot synthesis of multisubstituted imidazoles catalyzed by Dendrimer-PWA<Superscript>n</Superscript> nanoparticles under solvent-free conditions and ultrasonic irradiation

An efficient, green and eco-friendly protocol has been developed for the synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles via one-pot condensation reaction using Dendrimer-PWAⁿ as catalyst under solvent-free conditions or ultrasonic irradiation in excellent yields. The reactions under conventional heating conditions were compared with the ultrasonic-assisted reactions. The operational simplicity, practicability and applicability of this protocol to various substrates make it an interesting alternative to previous procedures. The present methodology offers several advantages such as excellent yields, short reaction times, a cleaner reaction, and the absence of any tedious work-up or purification. The catalyst is easily separated from the products by filtration and also exhibits remarkable reusable activity. SEM, BET and DLS of the catalyst were also investigated after each reaction cycle.     

Application of <Emphasis Type="Italic">k</Emphasis><Subscript>0</Subscript>-INAA for the determination of essential and toxic elements in medicinal plants from West Pokot County,Kenya

Rapid determination of gross alpha and beta emitters in urine by liquid scintillation counting is discussed. This method is based on direct addition of urine into scintillation cocktail. ²⁴¹Am, ²³⁹Pu and ⁹⁰Sr were selected as model radionuclides. The LSA Hidex 300 SL equipped with Triple-Double-Coincidence-Ratio technique was used for sample measurement. The work focused on optimizing the LSC cocktail to urine volume ratio with respect to the model radionuclides. The overall efficiencies for ²⁴¹Am, ²³⁹Pu and ⁹⁰Sr were greater than 92 %; therefore, this method would be suitable for rapid determination of gross alpha/beta activity.     

Examination of Selectivities of Thermally Stable Geminal Dicationic Ionic Liquids by Structural Modification

Dicationic ionic liquids (ILs) are widely used as gas chromatography (GC) stationary phases as they show higher thermal stabilities, variety of polarities, and unique selectivities towards certain compounds. An important aspect contributing to them is that they show multiple solvation interactions compared to the traditional GC stationary phases. Dicationic ILs are considered as combination of three structural moieties: (1) cationic head groups; (2) a linkage chain; and (3) the counter anions. Modifications in these structural moieties can alter the chromatographic properties of IL stationary phases. In this study, a series of nine thermally stable IL stationary phases were synthesized by the combination of five different cations, two different linkage chains, and two different anions. Different test mixtures composed of a variety of compounds having different functional groups and polarities were analyzed on these columns. A comparison of the separation patterns of these different compounds on nine different IL columns provided some insights about the effects of structural modifications on the selectivities and polarities of dicationic ILs.     

Per Aqueous Liquid Chromatography (PALC) as a Simple Method for Native Separation of Protein A

Staphylococcal protein A (protein A) is an important protein frequently used in research studies within the fields of biomedicine and biotechnology. Due to some limitations in available protein purification methods which can hold the native structure of the protein A without changing the folding or adding histidine to structure of this protein, its separation in the native form is difficult. In this study, a new cost-effective and powerful technique was introduced for separation of the full-length and truncated forms of recombinant protein A, without any alteration in their 3D structures. Per aqueous liquid chromatography with bare silica gel stationary phase and water:acetonitrile as the mobile phase was proved to be an attractive choice among the range of separation methods. Similar to hydrophilic liquid chromatography, this method employs high percentage of water in mobile phase. The effects of mobile phase composition, pH, and salt concentration on the retention behavior of protein A on bare silica gel stationary phases were investigated. In this method, applying high amounts of aqueous solvent accompanied by a minimum percentage of organic solvent could successfully separate protein A with preservation of folding, and any affinity-tagged group such as histidine has not occurred on its structure. Purity of the fractions obtained by the proposed method was confirmed using SDS-PAGE, western blotting, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. According to the results of ELISA, separated proteins retained their ability of binding to antibody.     

Reverse phase HPLC determination of sunitinib malate using UV detector,its isomerisation study,method development and validation

Sunitinib malate, as an anticancer compound and a multi-targeted tyrosine-kinase inhibitor for treatment of glioma, was comprehensively studied by using different liquid chromatography methods. Since sunitinib malate shows Z-E isomerism, various reverse phase high performance liquid chromatography (RP-HPLC) programs were designed to access quantitative determination and good separation of Z-E stereoisomers. Moreover, some impurities including N-oxide and impurity B were to be separated from the main isomer with acceptable resolution. In the present work, different RP-HPLC programs were developed in which the type of mobile phase, flow rate, pH, and temperature were optimized to reach the best analysis conditions and control the rate of Z to E conversion. In addition, the effect of some operational parameters during the solution preparation including initial concentration of the analyte, temperature, pH, and type of solvent on the stability of Z isomer were investigated. The opted conditions for quantitative analysis were C8-Hector column as stationary phase, methanol as solvent, ammonium acetate buffer containing triethylamine as mobile phase, the pH of mobile phase of 8.5, the flow rate of 1.0 mL/min, and detection at 425 nm. In this situation the peaks of E and Z isomers were at 16.3 and 19.7 min. Full validation of the designed method was done based on ICH guidelines.     

Electrocatalytic determination of penicillamine using multiwall carbon nanotubes paste electrode and chlorpromazine as a mediator

In this study, we describe the application of carbon paste electrode modified with multiwall carbon nanotubes as a voltammetric sensor for determination of penicillamine (PA) in the presence of chlorpromazine as a mediator. This modified electrode showed very efficient electrocatalytic activity for the anodic oxidation of PA. The peak current of linear sweep voltammograms of PA increased linearly with it’s concentration in the range of 0.5–500 μM PA. The detection limit for PA was 0.2 μM. The RSDs for 1.0 and 10.0 μM PA were 1.1 and 1.7%, respectively. The proposed sensor was successfully applied for the determination of PA in human urine and tablet.     

Potentials of boiling heat transfer in advanced thermal energy systems

Journal of Thermal Analysis and Calorimetry - Boiling process is a highly efficient mechanism of heat transfer, which has an important role in industrial and domestic sectors. In this process, a...