Experimental studies of the hydrolysis kinetics of aqueous-alkaline solutions of sodium borohydride

Experimental data were used to study the hydrolysis kinetics and construct an approximating expression for calculation of quasistationary hydrolysis constants for sodium borohydride in a wide range of alkali concentrations and temperatures.     

Stability of aqueous-alkaline sodium borohydride formulations

Stability of sodium borohydride in the form of concentrated solutions and suspensions and solids corresponding to a crystal hydrate in composition was studied. The effects of temperature, concentrations of sodium borohydride and alkali, and nature of alkali metal cation on the rate of sodium borohydride hydrolysis were studied.     

Human Lanosterol 14-Alpha Demethylase (CYP51A1) Is a Putative Target for Natural Flavonoid Luteolin 7,3′-Disulfate

Widespread pathologies such as atherosclerosis, metabolic syndrome and cancer are associated with dysregulation of sterol biosynthesis and metabolism. Cholesterol modulates the signaling pathways of neoplastic transformation and tumor progression. Lanosterol 14-alpha demethylase (cytochrome P450(51), CYP51A1) catalyzes one of the key steps in cholesterol biosynthesis. The fairly low somatic mutation frequency of CYP51A1, its druggability, as well as the possibility of interfering with cholesterol metabolism in cancer cells collectively suggest the clinical importance of CYP51A1. Here, we show that the natural flavonoid, luteolin 7,3′-disulfate, inhibits CYP51A1 activity. We also screened baicalein and luteolin, known to have antitumor activities and low toxicity, for their ability to interact with CYP51A1. The K_d values were estimated using both a surface plasmon resonance optical biosensor and spectral titration assays. Unexpectedly, in the enzymatic activity assays, only the water-soluble form of luteolin—luteolin 7,3′-disulfate—showed the ability to potently inhibit CYP51A1. Based on molecular docking, luteolin 7,3′-disulfate binding suggests blocking of the substrate access channel. However, an alternative site on the proximal surface where the redox partner binds cannot be excluded. Overall, flavonoids have the potential to inhibit the activity of human CYP51A1 and should be further explored for their cholesterol-lowering and anti-cancer activity.     

Kinetics of the Catalytic Hydrolysis of Concentrated Aqueous Solutions of NaBH4 on Co/TiO2 Powder

Kinetics and Catalysis - The results of experimental studies on the hydrolysis of concentrated aqueous solutions of sodium borohydride in a concentration range of 1.05–6.3 mol/kg at...     

Auto-ignitions of a methane/air mixture at high and intermediate temperatures

A rapid compression machine (RCM) and a shock tube (ST) have been employed to study ignition delay times of homogeneous methane/air mixtures at intermediate-to-high temperatures. Both facilities allow measurements to be made at temperatures of 900–2000 K, at pressures of 0.38–2.23 MPa, and at equivalence ratios of 0.5, 1.0, and 2.0. In ST experiments, nitrogen served as a diluent gas, whereas in RCM runs the diluent gas composition ranged from pure nitrogen to pure argon. Recording pressure, UV, and visible emissions identified the evolution of chemical reactions. Correlations of ignition delay time were generated from the data for each facility. At temperatures below 1300 K, a significant reduction of average activation energy from 53 to 15.3 kcal/mol was obtained. Moreover, the RCM data showed significant scatter that dramatically increased with decreasing temperature. An explanation for the abnormal scatter in the data was proposed based on the high-speed visualization of auto-ignition phenomena and experiments performed with oxygen-free and fuel-free mixtures. It is proposed that the main reason for such a significant reduction of average activation energy is attributable to the premature ignition of ultrafine particles in the reactive mixture.     

Features of Hydrolysis of Concentrated Aqueous Alkaline Solutions of NaBH4 on Co/TiO2 Catalyst

Kinetics and Catalysis - Kinetic experiments were carried out on the hydrolysis of concentrated aqueous and aqueous alkaline solutions of NaBH4 with a Co/TiO2 catalyst. The experiments in the...     

Feasibility of Using Luminescence Spectroscopy for Analyzing Phthalates Upon Their Conversion into Fluorescein

Journal of Applied Spectroscopy - The feasibility of using the conversion of phthalates to fluorescein in analytical luminescence spectroscopy for the detection of phthalates is considered....     

Modeling of pH of concentrated aqueous solutions of sodium metaborate

Russian Chemical Bulletin - A phenomenological model is developed to take into account the effect of hydration complexes on the properties of electrolytes. The results of validation of the model...