Defects in GaSe grown by Bridgman method.

Optical quality GaSe crystals have been grown by vertical Bridgman method. The structural properties and micromorphology of a cleaved GaSe(001) surface have been evaluated by RHEED, SEM and AFM. The cleaved GaSe(001) is atomically flat with as low roughness as ∼0.06 nm excepting local hillock type defects. The hillock-type formations are round-shaped with a bottom diameter of ∼200 nm and a height of ∼20-35 nm. The drastic depletion of the hillock material by gallium has been indicated by EDX measurements.

Bioconcentration and biomagnification of mercury and methylmercury in North Sea and Scheldt estuary fish.

Total Hg and MMHg concentrations were assessed in more than 350 fish and shellfish samples. Hg concentrations in Greater North Sea fish of prey range from 0.039 mg kg(-1) wet weight (ww; for ray) to 0.61 mg kg(-1) ww (for dogfish) and for all other fish species, from 0.045 mg kg(-1) ww (for plaice) to 0.33 mg kg(-1) ww (for sand sole), with 95 +/- 2% of the Hg content in the MMHg form. In Belgian coastal zone, fish concentrations range from 0.063 mg kg(-1) ww for plaice to 0.13 mg kg(-1) ww for flounder, with 82-87% of the Hg content in the MMHg form. In fish of the Scheldt, which is a very polluted estuary, Hg levels, as well as the percent MMHg of the total Hg, were lower than in the two zones previously mentioned. The intraspecies variability is of the order of 50% in each of the three zones. In liver tissue, a much larger variability was observed than in muscle tissue, except for fish species of the Scheldt. In most cases, the MMHg fraction in a particular fish species is inversely related to the intraspecies variability. Bioconcentration and biomagnification factors (BCF and BMF, respectively) were assessed. MMHg-BMFs were a few orders of magnitude higher than Hg(inorganic)-BMFs, and for the same species were always highest in the Greater North Sea and lowest in the Scheldt. For each of the Belgian coastal zone four species, a weak positive correlation between Hg content and fish length was found; however, the larger the size-range, the better the correlation. Taking fish length into account, a statistically significant difference in contamination level was observed for species sampled from the different geographical zones.

Optimization of an rf-powered magnetron glow discharge for the trace analysis of glasses and ceramics.

A radiofrequency (rf) powered planar magnetron glow discharge ion source has been designed and coupled to a double-focusing mass spectrometer. Superposition of the electrical field of the plasma in the cathode dark space and the magnetic field obtained from a ring-shaped magnet located directly behind the sample (cathode) form the electron traps and enhance the sputtering and ionization efficiency of the ion source. In order to establish optimum conditions for the trace analysis of nonconducting materials, mass spectrometric studies have been carried out on the ion signal intensities and energy distributions of analyte and discharge gas ions depending on pressure.

Trace and surface analysis of ceramic layers of solid oxide fuel cells by mass spectrometry.

For the trace analysis of impurities in thick ceramic layers of a solid oxide fuel cell (SOFC) sensitive solid-state mass spectrometric methods, such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and radiofrequency glow discharge mass spectrometry (rf-GDMS) have been developed and used. In order to quantify the analytical results of LA-ICP-MS, the relative sensitivity coefficients of elements in a La(0.6)Sr(0.35)MnO(3) matrix have been determined using synthetic standards. Secondary ion mass spectrometry (SIMS) - as a surface analytical method - has been used to characterize the element distribution and diffusion profiles of matrix elements on the interface of a perovskite/Y-stabilized ZrO(2) layer. The application of different mass spectrometric methods for process control in the preparation of ceramic layers for the SOFC is described.

[Characteristics of thyroid cancer in combination with autoimmune thyroiditis]. / Nekotorye osobennosti raka shchitovidnoi zhelezy v sochetanii s autoimmunnym tireoiditom.

Remote results of the surgical treatment of 413 patients with carcinoma of the thyroid gland without autoimmune changes and 199 patients with thyroid carcinoma associated with an autoimmune component were studied. Remote results of the surgical treatment and indices of survival in the second group of patients were found to be better than those in patients without autoimmune changes in the thyroid gland.