Some new soliton solutions of a semi-discrete fractional complex coupled dispersionless system.

In this paper, a semi-discrete fractional derivative complex coupled dispersionless system is proposed. The properties of M-fractional derivative are utilized to convert discrete M-fractional derivative system to a classical discrete differential system. Then the invariant subspace method (ISM) is utilized to find dark, bright, kink and W-shaped soliton solutions for the proposed system.

Intracellular GSH content and HIV replication in human macrophages.

In vitro HIV-1 infection induced a significant decrease in intracellular reduced glutathione (GSH) in human macrophages. Such a decrease was observed at the time of infection corresponding to maximum release of virus from infected cells and was not related to cell cytotoxicity. GSH los was not related to its oxidation or leakage through the cell membrane. Inhibition of intracellular GSH synthesis by buthionine sulfoximine (BSO) did not further decrease GSH levels with respect to the decrease caused by HIV alone. However, treatment of macrophages with BSO significantly increased the HIV yield in the supernatant. Exogenous GSH strongly suppressed the production of p24 gag protein as well as the virus infectivity. Previous observations with other RNA and DNA viruses consistently showed that GSH antiviral effect occurred at late stages of virus replication and was related to the selective decrease of specific glycoproteins, such as gp120, which are particularly rich in disulfide bonds.

Fluorometric determination of urea by flow injection analysis.

Urea was determined using fluorometry with flow injection analysis. O-phthalaldehyde (OPA) reacts with enzymatically generated ammonia and sulfite in alkaline medium to give a highly fluorescent compound that has an excitation wavelength of 372 nm and an emission wavelength of about 430 nm. The method is more selective to ammonia than the one which uses mercaptoethanol in place of the sulfite. Urease was immobilized to a Pall Immunodyne membrane which is commercially available. The immobilization occurs through covalent bonding which results in a highly stable enzyme preparation. The enzymatic membrane was fitted in a 5 cm long, 0.125 inch o.d. Teflon tubing which served as the enzymatic reactor. The system is difficult to use for the analysis of urea in serum because some compounds normally present in serum fluoresce at the same wavelength. This results in higher values for urea. If the reaction system is to be used for the evaluation of urea in serum, a blank should be run so that urea concentration can be calculated by difference.

Effect of electrolytes on the retention behavior of some benzenesulfonates in electrochemically modulated liquid chromatography.

The effects of electrolytes on the retention behavior of some benzenesulfonates in electrochemically modulated liquid chromatography were studied. Both cations and anions were found to have considerable effects on retention. As cation size increases, retention decreases, while anions show more complicated effects were anionic size and charge distribution contribute to the overall behavior of anions. Large anions with a delocalized negative charge on the whole species result in lower retention times, and vice versa. Also, electrolyte concentration plays an important role in the retention behavior observed. Initially, as electrolyte concentration was increased retention increased due to electrostatic interactions of cations with the negatively charged stationary phase. However, retention starts to slightly decrease or increase after some specific electrolyte concentration depending on the nature of the electrolytic species. Finally, an interesting behavior of double peak appearance of a single solute was observed at low electrolyte concentrations and was attributed to the presence of other active sites on the carbon stationary phase.

Spectrophotometric determination of enzymatically generated hydrogen peroxide using Sol-Gel immobilized horseradish peroxidase.

Peroxidase entrapment in different Sol-Gel matrices was successful. The enzyme did not show a decrease in activity for at least 2 months as well as storage at room temperature and dry condition for periods exceeding 3 weeks. It was evident that the enzymatic activity was a function in the type of the alkoxysilane precursor. In addition, the optimum temperature which resulted in maximum enzymatic activity was also dependent on the type of Sol-Gel matrix. Excellent results were obtained for the determination of glucose in serum samples using soluble glucose oxidase in conjunction with the Sol-Gel entrapped peroxidase. The enzymatically produced hydrogen peroxide is oxidized by the entrapped peroxidase yielding oxygen which oxidizes the faint blue variamine blue into the intensely violet colored species (the molar absorptivity is about 1.8 x 10(4) 1 mol(-1) cm(-1)). The characteristics of this chromogenic system as well as optimized conditions for its use in the spectrophotometric determination of enzymatically generated hydrogen peroxide were investigated. Excellent agreement between the results obtained by the proposed method and the widely used standard method, utilizing a commercial reagents kit, was always observed.