Band gap fluorescence from individual single-walled carbon nanotubes

Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or ultraviolet light.     

Glycogenosis type III in the dog.

Enzyme and glycogen structure studies have been carried out on tissues of a glycogenotic dog, the clinical and pathological characteristics of which are reported in the accompanying paper. Liver glucose-6-phosphatase, leukocyte and liver acid maltase, and liver and skeletal muscle glycogen Phosphorylase all appeared largely unaffected. The activity of the muscle and liver debranching enzyme (amylo-l,6-glucosidase), determined by two independent assay methods, was, however, reduced to between 0 and 7 % of normal activity. Glycogen structure studies with Phosphorylase or iodine spectra revealed that the abnormally large amounts of glycogen found in liver and skeletal muscle had abnormally short branches, as would be expected for a deficiency of debranching enzyme. It is thus clear that the dog had suffered from the equivalent of Cori''s disease (limit dextrinosis, type III glycogen storage disease). Preliminary data indicate that it may be possible to identify heterozygotes based on a study of the debranching enzyme of leukocytes.     

Evaluation of Ewe Performance in 795 Selected Sheep Flocks in South-Eastern Norway

A study of ewe performance was undertaken in 795 sheep flocks based on data from the Norwegian Sheep Recording System. Herd level data included in the annual report for 1998 were used as the basis for the study. Average flock size was 75.3 ewes. The material was considered as representative of the better and more motivated sheep farmers in the mountain valley regions in south-eastern Norway. The average number of lambs born per ewe, inclusive (and exclusive) of barren ewes, was 1.89 (2.02), and of autumn lambs (those surviving from birth in the spring to autumn) 1.60 (1.66). The average autumn weight of the lambs corrected to 145 days of age was 42.4 kg, giving an overall performance of 67.9 kg lambs live weight per ewe. When including artificially reared lambs, overall performance was 70.4 kg per ewe. Artificial rearing of lambs, mostly triplets which had been removed from the ewe, was practised on 395 of the farms. In the 74 flocks with a rate of artificial rearing of more than 10% of all lambs, overall performance per ewe was 13.3 kg higher than in flocks with no artificial rearing. Total lamb mortality from birth to autumn recording, including stillborn lambs, was 12.44%. Mortality had a skewed distribution, some flocks having very high mortality figures. The arithmetic means (and medians) for mortality were as follows: 2.75 (2.29)% stillbirths, 2.93 (2.30)% died during the indoor feeding period, 0.88 (0.00)% at spring pasture, and 6.16 (4.40)% at summer pasture. In regression models using Proc Genmod in SAS^®, it was found that average number of autumn lambs per ewe was negatively associated with the rate of barren ewes, late lambing date (flock average day in year when lambing took place), and total lamb mortality. The corrected autumn weight of the lambs was positively associated with the average number of lambs born per ewe and non-fertility rate, and negatively associated with flock size and total lamb mortality. The Dala breed had a positive effect on number of autumn lambs per ewe, and Spæl breed a negative effect on corrected autumn live weight of the lambs.     

Serum enzyme determination in the study of liver disease in dogs

Glutamate dehydrogenase (GLDH), sorbitol dehydrogenase (SDH), 5''-nucIeotidase (5''-ND) and cholin esterase (CHE) were determined in the sera of 37 dogs with various liver diseases. The values for these parameters were compared with the values for aspartate and alanin aminotransferase (ASAT, ALAT), alkaline phosphatase (ALP), γ-glutamyl transferase (γ-GT) and albumin (ALB). GLDH was found to be the most sensitive enzyme parameter (sensitivity 92 %), its values also reflecting the degree of liver cell necrosis well. Next in sensitivity followed ASAT and ALP. SDH values were correlated to ALAT values but had a low sensitivity (43 %). 5''-ND discriminated markedly better between biliary tract disturbance and other lesions than ALP and somewhat better than γ-GT. CHE had a wide reference range, low sensitivity, and was not correlated to ALB. Single determinations of CHE may thus not be of diagnostic value in dogs.     

Individual feeding specialisation of a naïve vs. veteran predators

Abstract – We explored the incidence of individual feeding specialisation among a naïve predator (non‐native rainbow trout postsmolts) and two native experienced predators (sea‐run Arctic charr and sea‐trout) in a subarctic Norwegian fjord. Interindividual foraging niche stability was obtained by combining information on stomach contents (recent dietary niche) with trophically transmitted parasite infestation (time‐integrated historical dietary niche) of individual predators. Individual fish showed a high degree of resource specialisation as prey items such as gammarids and small fish (both potential intermediate host of parasites) rarely co‐occurred in stomachs. In both naïve and veteran predators, positive associations between the intensity of a specific parasite species and the occurrence of their respective intermediate host (gammarids or fish) in the stomachs of individual predators demonstrated temporally interindividual feeding specialisations. Several behavioural phenotypes clearly co‐existed in both naïve and veteran predator populations, including gammaridivore (benthic feeders), piscivore (pelagic feeders) or insectivore (pleuston feeders) individuals. The likely mechanism of this observed interindividual resource specialisation in the non‐native naïve predators involves a behavioural component of which rapid learning seems to be a key factor.     

Macroscopic, neat, single-walled carbon nanotube fibers

Well-aligned macroscopic fibers composed solely of single-walled carbon nanotubes (SWNTs) were produced by conventional spinning. Fuming sulfuric acid charges SWNTs and promotes their ordering into an aligned phase of individual mobile SWNTs surrounded by acid anions. This ordered dispersion was extruded via solution spinning into continuous lengths of macroscopic neat SWNT fibers. Such fibers possess interesting structural composition and physical properties.     

Zum Einfluß organischer Bodenbedeckung auf den lateralen Transport von Isoproturon auf der Bodenoberfläche

On the Effect of Organic Surface Cover on Lateral Transport of Isoproturon on Soil Surface The losses of the herbicide isoproturon with the surface runoff and the sediment loss have been measured by means of rainfall simulations on microplots (0.5 × 1 m²) with different mulch materials and increasing soil cover percentages (wheat straw vs. rape leafs). Soil cover by straw showed no significant effect on the runoff discharge, but the total loss of isoproturon increased between 22 and 37%. Soil cover by rape leafs diminished the runoff by between 13 and 61%, the reduction of isoproturon loss was in the same range. It was shown, that the different influences of different mulch materials on runoff and soil loss can lead to different pesticide losses. Therefore, the only giving of “mulch” without specification does not describe such experiments sufficiently.