Composite Zn1-x Cd x GeAs2 semiconductors: structural and electrical properties.

We present the studies of structural, transport and magnetotransport properties of [Formula: see text]Cd x GeAs2 crystals with the chemical content changing from 0 to 1. The structural studies indicate that this alloy exists as a composite two-phase material in almost the entire range of average chemical compositions. The two phase nature of our samples does have a significant influence on the carrier transport and magnetotransport of the composite alloy. The change of the conductivity type is observed at room temperature, from p-type for [Formula: see text] to n-type for x > 0.18, respectively. The Hall carrier mobility measured at room temperature decreases as a function of x from about 35 cm2 (V · s)-1 for the sample with x = 0 down to 3 cm2 (V · s)-1 for the sample with x = 0.233. For x > 0.233 the Hall carrier mobility shows an increase with x, up to the highest value around 875 cm2 (V · s)-1 observed for the sample with x = 1. Temperature dependent resistivity measurements indicate the presence of thermal activation of carriers with activation energy, E a, with values from 20 to 30 meV for all the studied samples. The temperature dependent Hall effect data show that the grain boundary limited transport is strong in all our samples. For the samples with [Formula: see text] the negative MR is observed at temperatures lower than 100 K and at low magnetic field values, [Formula: see text] T. This effect is interpreted as a weak localization phenomenon with low values of phase coherence length, [Formula: see text] nm.

High temperature magnetic order in Zn1-x Mn x SnSb2+MnSb nanocomposite ferromagnetic semiconductors.

We present studies of structural, magnetic, and electrical properties of Zn1-x Mn x SnSb2+MnSb nanocomposite ferromagnetic semiconductors with the average Mn-content, [Formula: see text], changing from 0.027 up to 0.138. The magnetic force microscope imaging done at room temperature shows the presence of a strong signal coming from MnSb clusters. Magnetic properties show the paramagnet-ferromagnet transition with the Curie temperature, T C, equal to about 522 K and the cluster-glass behavior with the transition temperature, T CG, equal to about 465 K, both related to MnSb clusters. The magnetotransport studies show that all investigated samples are p-type semiconductors with high hole concentration, p, changing from 10(21) to 10(22) cm(-3). A large increase in the resistivity as a function of the magnetic field is observed at T < 10 K and small magnetic fields, [Formula: see text] mT, for all the studied samples with a maximum amplitude of the magnetoresistance about 460% at T = 1.4 K. The large increase in the resistivity is most probably caused by the appearance of the superconducting state in the samples at T < 4.3 K.

California black oak response to nitrogen amendment at a high O3, nitrogen-saturated site.

In a nitrogen (N) saturated forest downwind from Los Angeles, California, the cumulative response to long-term background-N and N-amendment on black oak (Quercus kelloggii) was described in a below-average and average precipitation year. Monthly measurements of leaf and branch growth, gas exchange, and canopy health attributes were conducted. The effects of both pollutant exposure and drought stress were complex due to whole tree and leaf level responses, and shade versus full sun leaf responses. N-amended trees had lower late summer carbon (C) gain and greater foliar chlorosis in the drought year. Leaf water use efficiency was lower in N-amended trees in midsummer of the average precipitation year, and there was evidence of poor stomatal control in full sun. In shade, N-amendment enhanced stomatal control. Small differences in instantaneous C uptake in full sun, lower foliar respiration, and greater C gain in low light contributed to the greater aboveground growth observed.

Stomata open at night in pole-sized and mature ponderosa pine: implications for O3 exposure metrics.

Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) is widely distributed in the western USA. We report the lack of stomatal closure at night in early summer for ponderosa pine at two of three sites investigated. Trees at a third site with lower nitrogen dioxide and nitric acid exposure, but greater drought stress, had slightly open stomata at night in early summer but closed stomata at night for the rest of the summer. The three sites had similar background ozone exposure during the summer of measurement (2001). Nighttime stomatal conductance (gs) ranged from one tenth to one fifth that of maximum daytime values. In general, pole-sized trees (< 40 years old) had greater nighttime gs than mature trees (> 250 years old). In late summer, nighttime gs was low (< 3.0 mmol H2O m(-2) s(-1)) for both tree size classes at all sites. Measurable nighttime gs has also been reported in other conifers, but the values we observed were higher. In June, nighttime ozone (O3) uptake accounted for 9, 5 and 3% of the total daily O3 uptake of pole-sized trees from west to east across the San Bernardino Mountains. In late summer, O3 uptake at night was < 2% of diel uptake at all sites. Nocturnal O3 uptake may contribute to greater oxidant injury development, especially in pole-sized trees in early summer.

[Alpha 1-antitrypsin as an endogenous marker of protein-losing enteropathies]. / Alpha 1-antytrypsyna endogennym markerem jelitowej ucieczki bialka.

A novelty of the present studies is the use of alpha 1-antitrypsin (A-1--AT) as an endogenous marker of enteric protein loss. Enteric clearance of alpha 1-antitrypsin was determined in 10 patients with the symptoms of PLE, and in 6 healthy individuals. Alpha 1-Antitrypsin concentration has been assayed in single, random samples of feces collected from 42 patients and 12 healthy individuals (normal values: 1.31 +/- 0.72 mg/g of feces). Markedly increased enteric clearance and A-1-AT concentrations in single, random samples of feces have been found in patients with enteric lymphangiectasis, Crohn's disease, ulcerative colitis, and constrictive pericarditis, slightly lower in coeliac, chronic diarrhoea, nonspecific hemorrhagic colitis, esophagitis, lambliasis, hypogammaglobulinemia, Wiskott-Aldrich syndrome, Rendu-Osler-Weber syndrome, hepatitis in newborn, and Gilbert's disease. Statistically significant positive clearance has been noted (r = 0.997; p less than .001). A single assay of A-1-AT in feces is simple, repeatable, and sensitive technique in the diagnosis and evaluation of these diseases in which the symptoms of enteric protein loss are seen.

[Causes of lamb losses with special reference to listeriosis on a large-scale farm]. / Przyczyny padniec jagniat ze szczególnym uwzglednieniem listeriozy w gospodarstwie wielkostadnym.

Epizootiological studies on lamb losses on a large scale farm (4.5 thousand mothers) were carried out. The results of the studies denied the direct effect of maize silage on the genesis of enzootia of listeriosis. The earlier reports were confirmed, i.e. that the direct cause of enzootia of listeriosis is the weakening of an animal organism due to other microbiological, zoohigienical, nutritional factors (e.g. not proper content of mineral compounds). Maize silage has a destructive effect on the health of lambs as well as other fodders with unsuitable biochemical composition. The results of the studies were prepared in Basic language using Hellwig's method "Determination of the maximum capacity of data carrier", to enable the automation of statistical data. Verification of the above mentioned method was done on the basis of the results of the studies performed on a sheep farm. Essential influence of the content of magnesium and iron as well as statistically known interdependencies between the indices studied were revealed and confirmed. "Listing" of the programme; data and result printout, to be used widely, was enclosed.

Plasma levels of LH and prolactin in cows following enucleation of the persistent corpus luteum.

LH and prolactin were measured in plasma of 5 cows before and after enucleation of the persistent corpus luteum. Two cows returned to normal oestrous cycles following enucleation and did not differ from normal, cycling cows, with respect to hormone levels. Three other ones developed follicular cysts following enucleation and had decreased levels of LH and prolaction as compared with cycling cows. On the day of enucleation the fluctuations in LH-levels were higher than either before or after enucleation.