Nanoscale Smoothing and the Analysis of Interfacial Charge and Dipolar Densities

The interface properties of interest in multilayers include interfacial charge densities, dipole densities, band offsets, and screening-lengths, among others. Most such properties are inaccesible to direct measurements, but are key to understanding the physics of the multilayers. They are contained within first-principles electronic structure computations but are buried within the vast amount of quantitative information those computations generate. Thus far, they have been extracted from the numerical data by heuristic nanosmoothing procedures which do not necessarily provide results independent of the smoothing process. In the present paper we develop the theory of nanosmoothing, establishing procedures for both unpolarized and polarized systems which yield interfacial charge and dipole densities and band offsets invariant to the details of the smoothing procedures when the criteria we have established are met. We show also that dipolar charge densities, i. e. the densities of charge transferred across the interface, and screening lengths are not invariant. We illustrate our procedure with a toy model in which real, transversely averaged charge densities are replaced by sums of Gaussians.Comment: 30 pages, 15 figures, 4 table

Comparison of risk patterns in carcinoma and melanoma of the skin in men: a multi-centre case–case–control study

We directly compared risk factors between 214 histologically confirmed melanomas (CMM), 215 basal-cell carcinomas (BCC) and 139 squamous-cell carcinomas (SCC) in a multiple case–case–control study with 349 controls from patients without dermatological disease admitted to the same hospitals. Subjects with fair hair had a significant risk increase for all types of tumours at a comparable level (ORadj for blonde hair: CMM 2.3; SCC 2.4; BCC 2.3). The effect of pale eyes was significant and similar for CMM and BCC (ORadj 2.6). Intermittent sun exposure measured in hours spent at beach during holidays was significant for both CMM (ORadj 2.6 for more than 7000 lifelong hours) and BCC (ORadj 2.1 for more than 7000 lifelong hours), while SCC exhibited a significant risk increase for chronic exposure to sunlight measured in hours of outdoor work (ORadj 2.2 for more than 6000 lifelong hours). In the case–case comparison using a multinomial logistic regression model, we found a statistically significant risk difference for pale eyes, and number of naevi in the CMM group, compared to other skin cancers. For intermittent sun exposure, there was a significant risk difference of BCC when compared to the risk of SCC. Factors influencing risk of SCC are different, with chronic exposure to sun playing a major role in causing this type of carcinoma

Enzyme-aided Wool Dyeing: Influence of Internal Lipids

Dyeing and diffusion properties of dyes into wool fiber are governed by a membranous structure which is formed by a matrix protein and lipid components. External lipids (wool wax) are mainly non-polar, while internal lipids consist mainly of sterols, polar lipids (ceramides), and free fatty acids. These components constitute a real hydrophobic barrier to the diffusion of dye molecules and in fact conventional wool dyeing methods are based on long times at temperature near the boil in order to ensure good levels of dye penetration. To limit the action of this barrier and to achieve higher values of dye bath exhaustion operating at temperatures lower than 98 oC, wool fabric was subjected to three different pre-treatments. The first pre-treatment consisted of the removal of internal lipids by extraction with solvents in order to obtain a higher affinity of the fiber towards the dyes. The second involved hydrolysis with a protease, which leads to the formation of access routes within the fiber to improve the uptake of dyes or other reagents. Finally, the third took into account the combined action of the two previous pre-treatments. The influence of each individual pre-treatment and their combinations on the kinetics and final exhaustion of the dye bath were studied, and assessment of color fastness (to washing and to light) were carried out

Applicazione degli enzimi nella tintura della lana

In questo lavoro è stata studiata la possibilità di ridurre la temperatura di tintura convenzionale della lana mediante l’impiego di enzimi proteolitici. Differenti proteasi di origine batterica sono state testate al fine di migliorare l’accessibilità del colorante alla fibra anche a basse temperature. Per ogni tintura sono state determinate le curve di esaurimento del colorante nel bagno di tintura. I campioni tinti sono stati sottoposti ad una valutazione di danneggiamento mediante osservazione al microscopio elettronico a scansione e a prove dinamometriche per valutare la perdita di carico di rottura ed allungamento. Inoltre, i campioni tinti sono stati sottoposti a prove di solidità ad umido e alla luce, parametro molto importante perché legato alla qualità del materiale ottenuto

Application of enzymes in wool dyeing

The application of enzymes in wool dyeing process is an important goal of research in order to reduce the environmental impact and costs of this fundamental finishing process of wool. This work has focused on the possibility of reducing the temperature of conventional dyeing, using an enzymatic pretreatment. Proteolytic enzymes belonging to hydrolase class were used to improve the diffusion of the dye into the fibers at lower temperatures than traditional method, with or without auxiliary agents. Exhaustion curves of the dye bath apparent activation energy values and absorption rate constants were determined. The protection of wool fiber properties during the treatments has been investigated. In order to evaluate a possible fiber damage, the dyed samples were observed by scanning electron microscopy (SEM) and at the same time the loss of tensile strength and elongation were determined. The attack degree of the enzyme was controlled by SDS-Page analysis. In addition, colour fastness to domestic laundering, artificial light, rubbing and perspiration were carried out. These are very important parameters related to the quality of the material produced. The results of this study show the possibility, thanks to the use of the enzyme investigated, to obtain an homogeneous and strenght dyeing, on fibers maintaining the same mechanical properties, already working at 85°C, a temperature process clearly under 98°C currently used in industry