The BLM-system for studying the electrophysical properties of bilayer lipid membranes (BLM) was applied to investigate interactions between polyamidoamine (PAMAM) dendrimers and lipid bilayers. The cationic PAMAM G5 dendrimer effectively disrupted planar phosphatidylcholine membranes, while the hydroxyl PAMAM-OH G5 and carboxyl PAMAM G4.5 dendrimers had no significant effect on them.
Influence of the measuring procedure on the repeatability of measurement of the potential oxygen flux density in the soil has been presented. Five measuring procedures were applied: measurements taken one directly after another, reinstallation of the electrode after each measurement , reinstallation of the electrode after each measurement with a simultaneous mechanical cleaning of surfaces, measurements with 15-min breaks between consecutive measurements, measurements with electrochemical "cleaning" of the electrode surface.The OFD value was determined by a voltamperometric method using a tri-electrode measuring system. It was found out that the best repeatability can be obtained by repeating the measurement with 15-min (or longer) time intervals.
The adsorptive stripping differential pulse voltammetric method was proposed for the determination of fenitrothion [O,O-dimethyl O-(4-nitro-m-tolyl)phosphorothioate]. The voltammetric response was evaluated in 0,04 mol -1 Britton-Robinson buffer with respect to the accumulation time and potential, and concentration dependence. The relationship between peak current and fenitrothion concentration was linear within the range of 1x10-8 – 1x10-6 mol l-1. In spiked water the detection limit of fenitrothion, estimated from 3 times the standard deviation, was 36 ng l-1. Interference from some other organophosphorus insecticides on the determination of fenitrothion were studied.
Przedstawiono wyniki badań dotyczące pomiarów gęstości strumienia tlenu (OFD) w dwuelektrodowym symetrycznym układzie elektrod platynowych i stalowych. Krzywe woltamperometryczne uzyskane w różnie natlenionych roztworach wskazują na możliwość eliminacji elektrody porównawczej.
Concentrations of lead, cadmium, copper and zinc in Lowland and Merino wool fibres were determined using differential pulse voltammetry, and iron concentration was measured by means of the spectrophotometric method. A differentiation in the concentration of the above elements in the same staple was Pb: 13.5-29.31 [mg/kg]; Cd: 0.95-4.59 [mg/kg]; Zn: 57.21-91.34 [mg/kg]; Cu: 2.79-5.91 [mg/kg]; Fe: 58.94-830.08 [mg/kg] for Polish Merino fleece, and Pb: 5.88-11.79 [mg/kg]; Cd: 1.35-4.92 [mg/kg]; Zn: 55.52-86.85 [mg/kg]; Cu: 1.66-4.58 [mg/kg]; Fe: 70.27-614.34 [mg/kg] for Polish Lowland fleece. The effects of metal pollution on structural and utilizable conditions were investigated.
Przedstawiono dwie metody oznaczania jonów jodkowych (spektrofotometryczną i woltamperometryczną). Sprawdzono zgodność jodowania soli spożywczych z Polską Normą.
The heavy metals cadmium, nickel, lead, molybdenum and zinc were determined in 19 samples of moss taken from 19 points situated in the Gliwice and Sanok areas. Samples (segregated, cleaned and powdered) were digested by the wet method in the microwave mineralizer. Differential pulse anodic stripping voltam- metry (DPASV) was used for determination of Cd, Ni, Mo, Pb and Zn. Oriental tobacco (CTA-ATL-1) as the certified reference material was applied in those investigations.
14
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
The intracellular second messenger nitric oxide (NO) is implicated in a variety of physiological functions, including release and uptake of dopamine (DA). In the described study, in vivo microdialysis and differential pulse voltammetric techniques were used to determine the involvement of NO in release of DA and its metabolites (dihydroxyphenylalanine, DOPAC; homovanillic acid, HVA) in neostriatum of freely moving rats. While the NO donor molsidomine (30.0 mg/kg; MOLS) and neuronal NO synthase- (nNOS-) inhbitor 7-nitroindazole (10.0 mg/kg; 7-NI) had no effect on the basal in vivo microdialysate level of DA, 7-NI specifically enhanced D,L-amphetamine- (1.0 mg/kg i.p.; AMPH) evoked release of DA. Basal or AMPH effects on DOPAC and HVA levels were not influenced by MOLS or 7-NI. Findings indicate that nitrergic systems have an important role in mediating effects of AMPH on dopaminergic systems.