Preparation, isolation, analysis, and characterization of 3-benzo[a]pyrenyl-beta-D-glucopyranosiduronic acid: a metabolite of 3-hydroxybenzo[a]pyrene with potentially high carcinogenic activity

The aglycone, 3-hydroxybenzo[a]pyrene, was metabolized to 3-benzo[a]pyrenyl-beta-D-glucopyranosiduronic acid in the presence of uridine 5'-diphosphoglucuronic acid and rabbit liver microsomes. The course of the biosynthetic reaction was followed by fluorimetry and reverse-phase, paired-ion high pressure liquid chromatography (HPLC). Also, the HPLC system was used to analyze for glucuronide and 3-hydroxybenzo[a]pyrene during the isolation procedure. The existence of a glucuronide of 3-hydroxybenzo[a]pyrene was determined by radiotracer and enzymic techniques, utilizing the HPLC system. Field desorption and direct inlet mass spectral techniques were used to characterize the 3-hydroxybenzo[a]pyrene glucuronide.     

Heat denaturation of hemocytocardiotoxin from the venom of the Central Asian cobra

It has been stated that boiled for three hours haemocytocardiotoxin (HT) from cobra poison loses "direct" hemolytic activity and is unable to potentiate a haemolytic effect of phospholipase A. Surface activity of HT does not change. It is shown that in the course of heat denaturation the aggregation of toxin molecules to dimers and trimers takes place and electrophoretic mobility is decreased. The fluorescence of HT tyroxin residues supported the fact of its irreversible heat denaturation.     

System for in situ studies of atmospheric corrosion of metal films using soft x-ray spectroscopy and quartz crystal microbalance

We present a versatile chamber ("atmospheric corrosion cell") for soft x-ray absorption/emission spectroscopy of metal surfaces in a corrosive atmosphere allowing novel in situ electronic structure studies. Synchrotron x rays passing through a thin window separating the corrosion cell interior from a beamline vacuum chamber probe a metal film deposited on a quartz crystal microbalance (QCM) or on the inside of the window. We present some initial results on chloride induced corrosion of iron surfaces in humidified synthetic air. By simultaneous recording of QCM signal and soft x-ray emission from the corroding sample, correlation between mass changes and variations in spectral features is facilitated.     

Outcome variables for the study of periodontal regeneration

The most reliable outcome variable for assessing periodontal regeneration is human histology; however, the morbidity associated with this technique makes it feasible only in isolated case studies designed to prove that a drug, device, or technique is capable of regenerating the lost periodontium including bone, cementum, and functionally oriented periodontal ligament. In the absence of this genuine variable, other "surrogate" variables must be used. Of these, measurement of new bone is the primary alternative. Direct bone measurements, including linear and volumetric assessment, are by far the best tools; however, the need for a second surgical procedure is a definite drawback of this technique. To overcome this problem, other outcomes have been employed: sounding bone measurements is a less invasive method, albeit it is also less accurate. Another tool that has been tested extensively is radiographic analysis. Conventional radiography is not useful in most regenerative trails where minimal or no crestal changes occur. The use of standardized radiographs and image processing techniques to measure alveolar bone changes has not significantly enhanced the applicability of this method. Digital subtraction radiography (DSR) offers some improvement over previous techniques; however, the correlation between the magnitude of clinical bone changes and changes in the digital image is yet to be substantiated. Other variables have been successfully used in regenerative studies. These include clinical attachment level changes, change in probing depth, and gingival recession. The information derived from these variables, especially attachment level changes, supplement and substantiate the direct bone measurements. Other variables that may be monitored are those associated with plaque formation, periodontal pathogens and gingival inflammation; while not direct measures of regeneration, these variables are likely to affect future prognosis and treatment stability. In summary, direct bone measurements are the most ideal surrogate outcome variable, although clinical attachment level measurements are commonly used in large-scale regenerative clinical trials. Clinical response may be assessed at different time intervals; however, the endpoint measurements for regenerative studies should be taken at least 12-months postoperatively.     

Diffusion in infinitely dilute polystyrene solutions

The validity and range of applicability of the Kirkwood-Riseman theory is examined by utilizing diffusivity data taken on infinitely dilute polystyrene solutions. The predictions of the theory are found to be in good agreement with diffusivity data obtained on the polystyrene–cyclohexane system at the theta temperature. It is concluded that diffusivity data which are in substantial disagreement with predictions based on the Kirkwood-Riseman approach are unreliable because of mixing effects which take place in a wedge interferometer when organic solvent–polymer systems are used. An extension of the Kirkwood-Riseman theory to polymer diffusion under nontheta conditions is presented and this modification satisfactorily represents diffusivity data when excluded volume effects are important.     

Improved performance in ZnO/CdS/CuGaSe2 thin‐film solar cells

We report the growth and characterization of improved efficiency wide‐bandgap ZnO/CdS/CuGaSe₂ thin‐film solar cells. The CuGaSe₂ absorber thickness was intentionally decreased to better match depletion widths indicated by drive‐level capacitance profiling data. A total‐area efficiency of 9·5% was achieved with a fill factor of 70·8% and a V_oc of 910 mV. Published in 2003 by John Wiley & Sons, Ltd.