Corona?A Brief Status Report

Relevant to many practical applications [1] including xerography [2]-[9], the various forms of gas discharge which can occur in asymmetrical gaps (for example, needle-to-plane geometry) have been briefly summarized in this status report. Due to its engineering importance, emphasis have been placed upon corona in atmospheric air, particularly l) the positive glow corona, especially the emerging controversy concerning the role of negative ions, and 2) the negative Trichel pulse corona, particularly the latest research in this field including the transition to sparking. Although a considerable body of knowledge is available, controversies remain, and there are many interesting things left to be done.     

Radiochemical study of the radical copolymerization of styrene and methyl methacrylate

The rates of initiation for the copolymerization of styrene and methyl methacrylate at 50°, in different reaction media (bulk, acetone, dimethylformamide and dioxane) have been determined by using the isotopic labelling technique (¹⁴C - azobisisobutyronitrile). For all mixtures, except dioxane, the experimental data do not support the linear interpolation of the initiation rates, which is usually adopted in literature. In the whole range of monomer feed compositions, any modification of the reaction medium causes a relevant change of the initiation rate, so that the overall pattern is markedly modified. The strongest solvent effect is given by dioxane, which reduces the initiation rates for all monomer mixtures.The radioactive tracer method also enables the determination of the modes of termination, which occur almost exclusively by combination for monomer feed compositions up to about 70 molar % of methyl methacrylate. The $\text{P}\text{?}{}_{\mathrm{w}}\text{P}\text{?}{}_{\mathrm{n}}$ ratios obtained by g.p.c. confirm the general trend of the termination mechanisms as a function of monomer mixture and reaction medium.     

Purification and properties of filamin, and actin binding protein from chicken gizzard

Filamin, a protein recently identified in chicken gizzard (Wang, K., Ash, F., and Singer, S. J. (1975) Proc. Natl. Acad. Sci. U. S. A. 72, 4483-4486), has been purified free of other components and its molecular properties have been examined. Filamin has a sedimentation constant (S020,w) of 8.86 S and a partial specific volume of 0.734 ml/g. Sedimentation equilibrium experiments give a value of 498,000 for the molecular weight of native filamin. From these data a frictional ratio of 2.32 has been calculated. On sodium dodecyl sulfate gel electrophoresis, filamin migrates as a single protein band with an estimated molecular weight of 240,000. Filamin is a soluble protein and under a variety of conditions tested does not by itself form filaments or precipitate from solution. However, filamin binds to rabbit skeletal muscle F-actin, and the complex is readily sedimented by centrifugation to yield a gelatinous pellet containing actin and filamin. These results indicate that filamin is a dimeric protein with a moderate degree of asymmetry that binds to actin. The results also suggest that the distribution of filamin in cells is derived from its interaction with polymerized actin.     

'Isolated' pulmonary valve stenosis as part of more widespread cardiovascular disease

In 25 patients aged 6 days to 9 years presenting as 'isolated' pulmonary valve stenosis, histology of the myocardium of right and left ventricles, coronary arteries, and ascending aorta has shown abnormality in one or all these areas. Myocardial necrosis, old and recent, unrelated to coronary occlusion was frequent. Myocardial 'dysplasia' involving both ventricles, and resembling hypertrophic cardiomyopathy (HOCM, ASH) was found in 10 and a relation of this to myocardial injury in the fetus is postulated. Varying degrees of coronary occlusion were frequently seen in both right and left coronary arteries. The histology of the ascending aorta was abnormal showing 'higgledy-piggledy' disorder of smooth muscle components in 12 (48%). In a different series of 53 patients who had pulmonary valvotomy for apparent 'isolated' pulmonary valve stenosis there were 14 with clinical evidence of left ventricular abnormality consistent with the pathological changes described, 2 with the same aortic histological changes, and 2 with macroscopical left ventricular hypertrophy. Two of them developed classical hypertrophic cardiomyopathy years later. It is suggested that when pulmonary valve stenosis presents with a thick tricuspid poorly mobile valve, particularly in infants or in patients with evidence of other congenital stigmata, it may be part of a more widespread cardiovascular abnormality. This should be recognized and considered in the evaluation of surgical patients and late survivors who may show unexpected clinical features.     

Antibacterial activity of lactose-binding lectins from <i>Bufo arenarum</i> skin

Amphibians respond to microbial infection through cellular and humoral defense mechanisms such as antimicrobial protein secretion. Most humoral defense proteins are synthetized in the skin. In this study we isolated two β-galactoside-binding lectins with molecular weights of 50 and 56 KDa from the skin of Bufo arenarum. These lectins have significant hemagglutination activity against trypsinized rabbit erythrocytes, which was inhibited by galactose-containing saccharides. They are water-soluble and independent of the presence of calcium. The antimicrobial analysis for each lectin was performed. At µmolar concentration lectins show strong bacteriostatic activity against Gram negative bacteria (Escherichia coli K12 4100 and wild strains of Escherichia coli and Proteus morganii) and Gram positive bacteria (Enterococcus faecalis). The antibacterial activity of these lectins may provide an effective defense against invading microbes in the amphibian Bufo arenarum.     

Development of silver nano-coatings on silk sutures as a novel approach against surgical infections

The infections give rise to a range of clinical problems and prolong hospitalization with increased healthcare costs. Moreover, persistent infections exasperate the problem of antibiotic resistance. The aim of this study was the development of effective and low-cost antibacterial silver coatings on surgical sutures by adopting an innovative photochemical deposition process to prevent early contamination of surgical wounds. The silver deposition technology adopted in this work is an innovative process based on the in situ photoreduction of a silver solution. The samples were dipped in the silver solution and then exposed to UV radiation in order to induce the synthesis of silver clusters on the surface of the suture. The homogeneous distribution of silver particles on the surface and on the cross-section of the treated sutures was demonstrated. All the antibacterial studies clearly demonstrated that the use of novel silver treated sutures could represent clinical advantages in terms of the prevention of surgical infections against bacterial colonization. The silver coating deposited on the sutures demonstrated no cytotoxic effect on a selected cell population. The results obtained suggested that the antibacterial silver-coated sutures developed in this work could represent an interesting alternative to conventional sutures, with evident advantages in terms of prevention of the surgical infections and on the health costs. In addiction, very low concentrations of silver significantly inhibited the microbial load, without affecting the cell viability.     

CC-RANSAC: Fitting planes in the presence of multiple surfaces in range data

Range sensors, in particular time-of-flight and stereo cameras, are being increasingly used for applications such as robotics, automotive, human-machine interface and virtual reality. The ability to recover the geometrical structure of visible surfaces is critical for scene understanding. Typical structured indoor or urban scenes are often represented via compositional models comprising multiple planar surface patches. The RANSAC robust regression algorithm is the most popular technique to date for extracting individual planar patches from noisy data sets containing multiple surfaces. Unfortunately, RANSAC fails to produce reliable results in situations with two nearby patches of limited extent, where a single plane crossing through the two patches may contain more inliers than the “correct” models. This is the case of steps, curbs, or ramps, which represent the focus of our research for the impact they can have on cars’ safe parking systems or robot navigation. In an effort to improve the quality of regression in these cases, we propose a modification of the RANSAC algorithm, dubbed CC-RANSAC, that only considers the largest connected components of inliers to evaluate the fitness of a candidate plane. We provide experimental evidence that CC-RANSAC may recover the planar patches composing a typical step or ramp with substantially higher accuracy than the traditional RANSAC algorithm.     

Alginate beads and apple pieces as carriers for Saccharomyces cerevisiae var. boulardii,as representative of yeast functional starter cultures

This study focused on two different carriers for Saccharomyces cerevisiae var. boulardii for its targeted release as a starter or as a probiotic: the microencapsulation into alginate beads and the immobilisation on apple pieces. Beads were studied in relation to encapsulation yield (EY), viability of cells throughout the storage, kinetic of cell release, survival under conditions that mimic the transit into the gut and in vivo application (fermentation of grape juice). Concerning the microencapsulation, EY was very high (ca. 90%), cells survived for a long period (upon to 90 days), and the beads assured cell survival and their release under conditions that mimic the gut; moreover, the capsules could be used up to ten times to start a model fermentation of grape juice. Apple pieces were a good system for the immobilisation of S. boulardii; they could be proposed successfully as a reusable carrier for a starter culture, as they assured the start of the fermentation of grape juice for at least seven times.