Ethane oxidehydrogenation selectivity and reductibility of mixed NiVSb oxides

Alumina-supported NiV, SbV and NiVSb oxides were characterized and tested as catalysts for the oxidehydrogenation of ethane. The results of their surface and bulk reduction by hydrogen revealed that the most easily reduced NiVSb catalyst was the most selective. The relationship between catalyst reducibility and selectivity was interpreted on the assumption that the reaction occurred through a redox mechanism.     

Generalization of Frei and Chen's approach to extract the lines and edges of a digital image

This work proposes the generalization to any k dimension of the approach suggested by Frei and Chen for line and edge detection in a digital image with square masks. With the proposed algorithm we can obtain information about the image lines and edges without modifying the rest of the image. To test these results we have applied the algorithm to biomedical images and geophysical images of archaeological prospections achieving optimal results.     

Phenotypic and genotypic biotyping of environmental strains of Vibrio cholerae non-O1 isolated in Italy

The purpose of this study was to characterize strains of Vibrio cholerae non-O1 isolated in Italy from different sources by biochemical and serological assays, antibiotic susceptibility testing, and molecular biotyping. Serotyping and genomic analysis by pulsed-field gel electrophoresis proved to be useful in discriminating the isolates. The data obtained show a wide heterogeneity at the genomic level, and in keeping with this, the serogrouping classification provided evidence of a high variability of the investigated strains. In addition, none of the strains tested produced cholera-like toxins.     

Friction and wear behaviour of Kevlar fabrics

Experimental results of a number of tribological tests carried out on aramid woven fabrics are presented in this paper. Kevlar Ht, Kevlar 29 and Kevlar 49 aramid plain fabrics were employed in this work. The friction and wear phenomena of the fabrics were investigated, considering both fabric-fabric and metal-fabric interaction. From the experimental data, the evolution of parameters such as static and dynamic friction coefficients, dissipated energy, volume loss of the material, wear rate, specific wear and wear strength were studied. Moreover, values of the static force needed to pull out a single fibre from the woven fabric were measured. All these data are important for the numerical modelling of impact on such materials. In fact, experimental findings on yarn failure mechanisms show that apart from tensile rupture, failure modes such as cutting, shearing and fibre degradation take place in fabrics subjected to the ballistic impact of low-and medium-calibre ammunition.     

Intrapartum prophylaxis with ceftriaxone decreases rates of bacterial colonization and early-onset infection in newborns

Because of high rates of neonatal gram-negative sepsis in many Latin American countries, we prospectively enrolled 784 high-risk pregnant women in a study designed to evaluate the effect of a single 1-g dose of ceftriaxone (n = 390) vs. that of no antibiotic prophylaxis (n = 394) on oral, rectal, and umbilical colonization and fatality rates among newborn infants. The mean ceftriaxone concentration in cord blood samples was 26 microgram/mL (range, 9-40 microgram/mL). Compared with infants of untreated mothers, children born to women who were given ceftriaxone were colonized at a lesser rate by gram-negative bacilli (54% vs. 35%; P < .001) and by group B streptococci (54% vs. 21%; P = .03) and endured significantly fewer sepsis-like illnesses in the first 5 days of life (8.1% vs. 3.1%; P = .004). There was also a tendency for them to have fewer episodes of culture-proven early-onset sepsis (2.8% vs. 0.5%; P = .06). Sepsis-related case-fatality rates (0.8% and 0.3%, respectively) were not significantly different. Although intrapartum administration of a single dose of ceftriaxone to high-risk mothers could be a safe and potentially useful strategy for reducing early-onset neonatal infections, additional information is required before this approach can be recommended for routine prophylaxis.