Phonons in MgB2 by Polarized Raman Scattering on Single Crystals

The paper presents detailed Raman scattering study of the unusually broad E2g phonon mode in MgB2 crystal. For the first time, it is shown by the polarized Raman scattering on few-micron-size crystallites with natural faces that the observed broad Raman feature really does obey the selection rules of an E2g mode. Raman spectra on high quality polycrystalline superconducting MgB2 wires reveal a very symmetric E2g phonon line near 615 1/cm with the room temperature linewidth of 260 1/cm only. Additional scattering of different polarization dependence, observed in certain crystallites is interpreted as weighted phonon density of states induced by lattice imperfections.Comment: 4 pages + 7 figure

Reaction kinetics of the formation of intermetallic Fe – Zn during hot - dip galvanizing of steel

This review article mainly describes the composition of intermetallic Fe - Zn, i.e. zeta (ζ), delta (δ1k + δ1p), gamma1 (Γ1) and gamma (Γ) on galvanized steel during low temperature galvanization (t ~ 450 °C). It gives detailed the formation, growth of individual phases during galvanization and their interaction. In terms of the kinetics, the formation of the coating is defined by a parabolic kinetic equation of the growth of different intermetallic phases under ideal conditions. From the available literature the rate constants of the formation of individual intermetallic phases and also for the total coating are cited. The composition of the intermetallic phases, iron content, crystal structure, and group symmetry in which the surface of galvanized steel forms

Corrosion properties of chromia based eco - friendly coatings on mild steel

Ceramic nanocrystalline coatings of chromium oxide (III) on steel S235JRH-1.0038 (EN 10025-1) were prepared using the liquid precursor plasma spraying (LPPS) method from ammonia dichromate (VI). Their structure and anti – corrosion properties were compared to the standard chromium oxide (III) coating prepared by thermal spraying. The newly prepared coatings had very high adhesion and minimal porosity. Anticorrosion properties were characterized by the means of the electrochemical impedance spectroscopy (EIS), measuring the charge transfer resistance Rct and capacitance of electrical double layer CPEdl in the 0,5 mol/l NaCl. Coatings of Cr2 O3 prepared by the LPPS method showed unambiguously improved anti - corrosion properties

Measurement of Electromagnetic Activity of Yeast Cells at 42 GHz

This paper discusses the possibility of using a device composed of a resonant cavity, preamplifiers, and a spectrum analyzer to detect electromagnetic emission of yeast cells at a frequency of about 42 GHz. Measurement in this frequency range is based on the Frohlich\'s postulate of coherent polar oscillations as a fundamental biophysical property of biological systems and on the experiments of Grundler and Keilmann who disclosed effects of exposure to the electromagnetic field at 42 GHz on the growth rate of yeast cells. This article includes a detailed description of the laboratory equipment and the methods used to evaluate the obtained results

Boronized steels with corundum-baddeleyite coatings

The paper describes preparation and properties of anti-corrosion and anti-abrasive coatings from corundum-baddeleyite ceramics deposited on surface of low-carbon boronized steel S235JRH-1.0038 (EN 10025-1) by plasma spraying method. Adhesive interlayers Fe2B reaches bond strength of up to 20 MPa in the pull-off tests, the ZrO2 - Al2O3 - SiO2 coatings have a value of fracture adhesion of 4 - 6 MPa. Hardness of these ceramic coatings on steel is as high as 1 800 HV100 and its polarization resistance is 1 600 Ω/cm2 to 4 000 Ω/cm2

Description of structure of Fe-Zn intermetalic compounds present in hot-dip galvanized coatings on steel

The article is describing formation, composition, morphology and crystallographic characteristics of intermetalic compounds Fe - Zn present in the coating formed during the process of low-temperature hot-dip galvanizing of carbon steels. In mutual confrontation we introduce older bibliography and results of latest modern researches based on combination of most precise analytical methods

Effect of chemical composition of steel on the structure of hot – dip galvanized coating

This article describes the effect of the content of conventional steel impurity elements on the thickness and composition of the zinc layer. This article is focused primarily on low-temperature, batch hot-dip galvanizing; however, the continuous coating process is also mentioned. The main discussion covers galvanizing from pure zinc melt, and only touches on galvanizing from melts with the usual amounts of aluminium (0,2 wt. %). Silicon, phosphorus, aluminium and sulfur may have an especially negative effect on the mechanical properties of the coating and its final appearance. The content of ballast carbon and manganese has a rather limited effect on composition and coating thickness

A produçao familiar como alternativa de um desenvolvimento sustentável para a Amazônia; Liçoes aprendidas de iniciativas de uso florestal por produtores familiares na Amazônia boliviana, brasileira, equatoriana e peruana

Abstract: Between 2005 and 2009, the EU-financed project ForLive set out to analyse promising local forest management initiatives in the Amazon Basin in four countries: Ecuador, Bolivia, Brazil, and Peru. Researchers aimed to identify locally viable practices that benefit livelihoods and ecological stabilisation of landscapes, as well as to define ways to promote these practices as a basis for sound rural development. This book presents lessons learnt from more than 100 studies by researchersfrom Latin America, from practitioners and from local families themselves. The findings suggest that the focus of current development strategies designed to support smallholders in adopting management and organization, which are usually externally defined systems made from expert-driven policy and research, mayrequire a review of fundamental assumptions and methods. Most of these initiatives widely ignored the immense potential of Amazonian smallholders—settlers, traditional communities and indigenous groups—to contribute to sound rural development with their own ideas and knowledge. Strong evidence was found that the socio-productive systems of Amazonian smallholders could serve as a reference for new methods that support a more equitable and environmentallysustainable development of the region

Security and Performance Trade-offs for Data Distribution Service in Flying Ad-Hoc Networks

This paper focuses on the data distribution service(DDS) middleware and its publish/subscribe logic - a topic thathas recently regained popularity in both academia as well asindustry. DDS is a well-known approach based on publish-subscribe logic. Therefore, only brief introduction of the issueis given followed by practical evaluation of current, availableand real implementations from the security and performancepoint of view. The analysis and evaluation is performed toaid comparison of competing DDS implementation, and thuscould serve well as an input to decision-making about whichof these solutions is best suited for a given situation. Finally,the practical performance evaluation is performed via severaldifferent scenarios to effectively compare the currently most-usedDDS implementations

The Parallel Complexity of Growth Models

This paper investigates the parallel complexity of several non-equilibrium growth models. Invasion percolation, Eden growth, ballistic deposition and solid-on-solid growth are all seemingly highly sequential processes that yield self-similar or self-affine random clusters. Nonetheless, we present fast parallel randomized algorithms for generating these clusters. The running times of the algorithms scale as $O(\log^2 N)$, where $N$ is the system size, and the number of processors required scale as a polynomial in $N$. The algorithms are based on fast parallel procedures for finding minimum weight paths; they illuminate the close connection between growth models and self-avoiding paths in random environments. In addition to their potential practical value, our algorithms serve to classify these growth models as less complex than other growth models, such as diffusion-limited aggregation, for which fast parallel algorithms probably do not exist.Comment: 20 pages, latex, submitted to J. Stat. Phys., UNH-TR94-0