Dielectric barrier discharge treatments at atmospheric pressure for wood surface modification

In this research, the effect of dielectric barrier discharge on mechanically manufactured (sawn, planed or polished) wood surfaces is investigated. The experiments have shown that the best hydrophilia is obtained with a cold plasma discharge in air under atmospheric pressure. Other gases such as helium, nitrogen, and argon have been tested, too. Changes of the wood surface properties were determined by absorption of water and contact angle measurements. As a result of a 1 to 20 seconds long exposure to plasma, wood surfaces became hydrophilic. The absorption of water in wood can be changed up to 22 times higher after plasma treatment in air for 20 seconds duration. The fracture strength of glued wood has been increased by 68% after this plasma pretreatment. Using plasma treatment in methane or acetylene wood surfaces are changed to hydrophobic properties. After plasma treatment for 1 min. in a Ar:CH₄=80:20 gas mixture under atmospheric pressure, the absorption of water in wood is 32 times lower than without plasma treatment. As mentioned before, plasma treatment can produce hydrophobic and hydrophilic wood surfaces. But a good homogeneity of the gas discharge is necessary for the plasma treatment of wood. Zusammenfassung Im Rahmen dieser Arbeit werden die Auswirkungen der dielektrisch behinderten Entladung bei Atmosphärendruck auf mechanisch bearbeitete Holzoberflächen (gesägt, gehobelt oder geschliffen) untersucht. Die Experimente haben gezeigt, dass die höchste Hydrophilität bei einem in Luftatmosphäre gezündetem Plasma erreicht wird. Es werden auch andere Gase verwendet, wie z.B. Helium, Stickstoff und Argon. Zur Untersuchung der veränderten mechanischen und energetischen Eigenschaften der Holzoberflächen werden der Tropfen-Versuch und die Kontaktwinkelmessung verwendet. Durch eine 1 bis 20 Sekunden lange Plasmabehandlung können die Oberflächen hydrophil gestaltet werden. So kann die Eindringzeit von Wasser um Faktor 22 gesteigert werden durch eine 20 Sekunden lange Plasmabehandlung in Umgebungsluft. Die Bruchfestigkeit von Leimholz wird durch die gleiche Plasmavorbehandlung um 68% gesteigert. Werden als Plasmabehandlungsgas Methan oder Acetylen eingesetzt, so wird die Holzoberfläche hydrophob. Durch eine 60 Sekunden lange Plasmabehandlung in einem Ar:CH₄=80:20 Gasgemisch bei Atmosphärendruck wird die Eindringszeit von Wasser um den Faktor 32 gesenkt. Mit Hilfe der Plasmabehandlung können also sowohl hydrophobe als auch hydrophile Holzoberflächen erzeugt werden. Jedoch wird für die Plasmabehandlung von Holz eine sehr homogene Gasentladung benötigt.     

Investigation of the potential of asymptotic homogenization for elastic composites via a three-dimensional computational study

Asymptotic homogenization is employed assuming a sharp length scale separation between the periodic structure (fine scale) and the whole composite (coarse scale). A classical approach yields the linear elastic-type coarse scale model, where the effective elastic coefficients are computed solving fine scale periodic cell problems. We generalize the existing results by considering an arbitrary number of subphases and general periodic cell shapes. We focus on the stress jump conditions arising in the cell problems and explicitly compute the corresponding interface loads. The latter represent a key driving force to obtain nontrivial cell problems solutions whenever discontinuities of the coefficients between the host medium (matrix) and the subphases occur. The numerical simulations illustrate the geometrically induced anisotropy and foster the comparison between asymptotic homogenization and well established Eshelby based techniques. We show that the method can be routinely implemented in three dimensions and should be applied to hierarchical hard tissues whenever the precise shape and arrangement of the subphases cannot be ignored. Our numerical results are benchmarked exploiting the semi-analytical solution which holds for cylindrical aligned fibers.     

In Memory of Our Great Friend Professor Dong Haishan

In October 1987 an international symposium on propellants, explosives and pyrotechnics was arranged in Beijing at the Beijing Institute of Technology. I participated in that symposium and presented a paper entitled "Sensitivity Test Methods for approval of Explosives in Sweden".     

Critical Evaluation of Current Hypotheses for the Pathogenesis of Hypertrophic Cardiomyopathy

Hereditary hypertrophic cardiomyopathy (HCM), due to mutations in sarcomere proteins, occurs in more than 1/500 individuals and is the leading cause of sudden cardiac death in young people. The clinical course exhibits appreciable variability. However, typically, heart morphology and function are normal at birth, with pathological remodeling developing over years to decades, leading to a phenotype characterized by asymmetric ventricular hypertrophy, scattered fibrosis and myofibrillar/cellular disarray with ultimate mechanical heart failure and/or severe arrhythmias. The identity of the primary mutation-induced changes in sarcomere function and how they trigger debilitating remodeling are poorly understood. Support for the importance of mutation-induced hypercontractility, e.g., increased calcium sensitivity and/or increased power output, has been strengthened in recent years. However, other ideas that mutation-induced hypocontractility or non-uniformities with contractile instabilities, instead, constitute primary triggers cannot yet be discarded. Here, we review evidence for and criticism against the mentioned hypotheses. In this process, we find support for previous ideas that inefficient energy usage and a blunted Frank–Starling mechanism have central roles in pathogenesis, although presumably representing effects secondary to the primary mutation-induced changes. While first trying to reconcile apparently diverging evidence for the different hypotheses in one unified model, we also identify key remaining questions and suggest how experimental systems that are built around isolated primarily expressed proteins could be useful.     

Goat milk consumption protects DNA against damage induced by chronic iron overload in anaemic rats

The effect of cow or goat milk-based diets, either normal or Fe-overloaded, on DNA stability was studied in control and anaemic rats for 30 or 50 days of chronic Fe repletion. DNA damage was assessed using the alkaline comet assay. Background DNA damage in lymphocytes of peripheral blood was much lower in control and anaemic rats, given the normal or Fe-overloaded goat milk-based diet after 30 and 50 days versus cow milk-based diet. Chronic Fe-overload had no adverse effect on DNA stability in control and anaemic fed the goat milk-based diet versus the same diet with normal-Fe content at the end of the study. The quality of goat milk fat, together with the high levels of bioavailable Mg and Zn may be responsible for its protective effect on DNA of peripheral blood lymphocytes under the different experimental conditions, even during chronic Fe-overload.     

Interactions among iron, calcium, phosphorus and magnesium in the nutritionally iron-deficient rat

We studied the development of nutritional iron deficiency 0, 10, 20, 30 and 40 days after the intake of a semisynthetic diet lacking iron (diet 0) and the possible interactions with calcium, phosphorus and magnesium in both control rats and rats after 40 days of iron deficiency. During this period, iron deficiency was found to produce stress in the rats, as evidenced by high levels of cortisol in the serum. High levels of parathyroid hormone (PTH) were also found. There was a considerable increase in the absorption of calcium, phosphorus and magnesium, but the phosphorus and magnesium balance decreased and that of calcium remained practically unchanged, although there was an increase in calcium urinary elimination. Despite the noticeable degree of bone demineralization, which was evident in the femur, serum levels of calcium, phosphorus and magnesium remained constant. The present study shows that severe nutritional ferropenic anaemia provokes significant alterations in the metabolism of calcium, phosphorus and magnesium. We conclude that these alterations should be taken into account in the treatment of this pathology, given its prevalence and the fact that it may exacerbate other pathologies, particularly those related to the metabolism of calcium and phosphorus.     

Validity, predictive efficiency, and practical significance of selection tests.

The acceptance of validity coefficients at face value as measures of practical significance is evaluated by examining each functional relationship between 3 indexes of predictive efficiency r, r2, and E and 3 measures of practical significance the increase of the criterion mean, the expected proportion "satisfactory," and the expected proportion in 10 criterion categories. The validity coefficient, r is a linear function of the increase of the criterion mean and very nearly a linear function of the other 2 measures of practical significance; r2 and E are related to these 3 measures in a more curvilinear manner. A table is presented that gives the proportion expected in each of 18 criterion categories as a function of r and the selection ratio. (PsycINFO Database Record (c) 2010 APA, all rights reserved)