Excited-state-absorption cross sections and amplifier modeling inthe 1300-nm region for Nd-doped glasses

The performance of Nd³⁺-doped fibre amplifiers is limited by strong excited-state absorption (ESA) of the signal, and, even for fluorozirconate glasses, ESA prevents the important region below 1320 nm from being used. To quantify this limitation and explore alternative host materials, ESA and stimulated-emission cross sections have been measured for a representative group of glass compositions. These parameters have been used in an accurate fiber-amplifier model to provide the first quantitative comparisons of performance for Nd³⁺ -doped glasses in the 1300-nm band as a function of host     

A New Immobilized Glucose Isomerase with High Productivity Produced by a Strain of Streptomyces murinus

The properties of a new immobilized glucose isomerase, produced by a selected strain of Streptomyces murinus, are described. The major advantages of the new immobilized enzyme are a productivity of more than 10,000 kg syrup dry substance per kg enzyme under optimal industrial conditions, increased activity and a very low syrup by-product formation. The influence of process parameters (temperature, pH and feed syrup additives) on activity and stability is discussed based on laboratory and industrial plant data.     

The critical transmural pressure of the abirway

The critical transmural pressure (Ptm) is defined as the transmural pressure of the airway at the site where and when flow is limited during a forced expiration. According to the presented theory, the maximal expiratory flow (Vmax) can be calculated from the relation between Ptm and the corresponding cross-sectional area of the airway (A). By means of a pitot-static tube, Ptm-A curves were constructed for several locations in the elastic airway of a mechanical model. From these curves local Vmax was calculated at different values of Ptm and compared with actual flow, i.e. measured Vmax for the entire airway. In the downstream part of the airway, the actual flow equalled calculated Vmax at most Ptm values. The site of flow limitation, being the most upstream point where actual flow equals calculated local Vmax could therefore be located. Theory and experiments showed positive as well as negative Ptm not influenced by change in upstream or downstream resistance. Flow limitation could therefore be initiated at distending as well as compressing pressures across the wall of the airway. V was regarded as a function of Ptm and the elastic recoil pressure of the lung (Pel). Measured and calculated iso-Pel, Ptm-V curves agreed well with one major exception: when Ptm less than Ptm measured curves were distorted due to a concomitant downstrean compression of the collapsible airway.     

Chemistry of denitrification in sporogenous soil bacteria

Soil sporeforming denitrifying bacteria, Bacillus filaris and Bacillus polymyxa, differ by their cultural-morphological and physiological characteristics, but are similar in the chemistry of dissimilating nitrate reduction. Two processes occur simultaneously: denitrification yielding gaseous nitrogen forms, and nitrate respiration upon which nitrates are reduced to ammonia. The ratio between the two depends on physico-chemical conditions of the environment. The chemistry of dissimilating nitrate reduction by sporeforming bacteria differs therefore from nitrate transformation by other denitrifying microorganisms: Pseudomonas, Micrococcus, Rhizobium, Achromobacter, which, according to the published evidence, are capable only of denitrification.     

Binding properties of bovine colostral anti-dinitrophenyl (dnp) immunoglobulins g2 (igg2)

The number of combining sites per mole of bovine colostral anti-DNP IgG2 was found to be 2 and the total affinity constant was 0.81 X 10(4) M-1. Unlike bovine colostral IgG1, the nonspecific binding of H3-epsilon-DNP-1-lysine by IgG2 as a function of increased concentrations, did not show a negative, cooperative slope. Spectral measurements made with anti-DNP IgG2 in the reference cell vs. anti-DNP IgG2 plus hapten in the experimental cell revealed a hypochromic, red shift from 363 to 365 nm. If the reference cell contained hapten, a red shift from 280 to 283 nm and an enhancement in the extinction coefficient of IgG2 was observed. These spectral changes were not observed if nonspecific IgG2 was substituted for anti-DNP IgG2 in the experimental cell. The enhancement in the extinction coefficient was interpreted to be due to a possible exposure of previously buried tryosine and tryptophan residues.     

Rapeseed meal glucosinolates: metabolism and effect on performance in laying hens

Two experiments were conducted with Hyline Leghorn hens to study the metabolism and detrimental effects of rapeseed meal (RSM) glucosinolates. Raw Target RSM was force fed to 12 hens which were killed after varying time intervals (15 min., 30 min., 60 min.) and the contents of areas of the digestive tract (crop; proventriculus and gizzard; duodenum and ileum) were analyzed for the presence of hydrolysis products of progoitrin. Nitrile compounds were found to be present in all areas of the digestive tract in much larger relative amounts than was oxazolidinethione. When commercially prepared RSMs of varying glucosinolate content were fed to laying hens at a 50% level of dietary inclusion, high glucosinolate-content RSM depressed egg production (P less than 0.05) more than low glucosinolate-content RSM but did not cause a greater frequency of liver hemorrhage. Histological examination of liver tissues from hens suffering liver hemorrhage revealed a severe reticulolysis.     

Effect of various hormonal preparations on trophoblast growth in tissue culture

The application of different methods of tissue culture, in particular, investigations on trophoblast cells outside the mother's body, opens new possibilities for understanding pathogenesis of premature interruption of pregnancy caused by the hormonal and metabolic disorders. To study the effects of various hormones (Choriogonien, estrone and estradiol) on the growth and development of trophoblast cells the method of tissue culture was applied. 683 histological preparations, obtained after incubating trophoblast tissues with and without hormones were examined. It was established that choriogonine in doses of 5-100 IU/L stimulated growth in trophoblast cells but 200-400 IU/L of hormone did not increase this stimulating effect. Estrone and estradiol added to incubated tissues in doses of 60-120 IU/L brought about no changes or else had a weak effect on development of cultivated tissues. When choriogonine (or estrone) was added to the trophoblast tissues together with blood serum taken from women in danger of premature interruption of pregnancy the negative effect of the serum on the development of the trophoblast cells was prevented.