Thermodynamic aspects of chemically curved crystals

The thermodynamic stability of an elastic material with a constant concentration gradient is analysed in linear approximation within the framework of the Ginzburg-Landau theory including an external inhomogeneous field. The result suggests ways to produce stress-free, paraboloidically curved finite size crystals.     

Surface investigations on annealed and boron implanted Fe80Mo7B12Cu1 amorphous ribbons

The effect of boron ion implantation (160 keV, (2–10)×10¹⁶ B⁺\cm²) and thermal annealing (410–580°C, 2 h) on metallic glass Fe₈₀Mo₇B₁₂Cu₁ was investigated by means of STM (Scanning Tunneling Microscopy), CEMS (Conversion Electron Mössbauer Spectroscopy), TEM (Transmission Electron Microscopy) and X-ray diffraction. The chosen material is known to become nanocrystalline after a suitable heat treatment. N⁺ ion implantation can also promote partial crystallization (restricted to α-Fe phase formation) of metallic glasses, especially in the case of small boron contents, as it was shown in a previous work. The as-quenched Fe₈₀Mo₇B₁₂Cu₁ has only paramagnetic moment at room temperature which makes it very easy to detect even small amounts of ferrogmagnetic α-Fe. According to our X-ray and CEMS investigations, even the high dosage boron metalloid implantation did not lead to partial crystallization of the 150 nm thick implanted layer. This can be the consequence of the implanted boron which is the glass forming metalloid component in our alloy. In other words, we have only found the disordering effect of the boron implantation which is in accordance with expectations. However, STM images reveal clear changes in the surface roughness of the samples. The number of features in the 50–150 nm size range are reduced, larger objects remain persistent, while smallers seem to change their shape due to boron ion implantation.     

Incomplete rescue of cystic fibrosis transmembrane conductance regulator deficient mice by the human CFTR cDNA

We have used a mouse model to study the ability of human CFTR to correct the defect in mice deficient of the endogenous protein. In this model, expression of the endogenous Cftr gene was disrupted and replaced with a human CFTR cDNA by a gene targeted 'knock-in' event. Animals homozygous for the gene replacement failed to show neither improved intestinal pathology nor survival when compared to mice completely lacking CFTR. RNA analyses showed that the human CFTR sequence was transcribed from the targeted allele in the respiratory and intestinal epithelial cells. Furthermore, in vivo potential difference measurements showed that basal CFTR chloride channel activity was present in the apical membranes of both nasal and rectal epithelial cells in all homozygous knock-in animals examined. Ussing chamber studies showed, however, that the cAMP-mediated chloride channel function was impaired in the intestinal tract among the majority of homozygous knock-in animals. Hence, failure to correct the intestinal pathology associated with loss of endogenous CFTR was related to inefficient functional expression of the human protein in mice. These results emphasize the need to understand the tissue-specific expression and regulation of CFTR function when animal models are used in gene therapy studies.     

Anomalies in additive colour matches

W.A. Thornton [W. A. Thornton, Toward a more accurate and extensible colorimetry, Parts I–III, Color Res. Appl. 17 , 79–122, 162–186, 240–261 (1992).] reported significant discrepancies in Maxwell colour matches when using different sets of primary lights. His experiments were performed by a small, mainly older group of observers. the aim of this investigation was to test these findings over wider age ranges. We matched a broad-band white light of constant luminance with two sets of three monochromatic primaries. These sets were similar to Thornton's AP set (497, 579, and 653 nm) and Thornton's PC set (452, 533, and 607 nm). Thirty-two observers performed the tests with 10° fields. the chromaticities of the matches made with the AP set had a large variance and were centered around the chromaticity of the reference white. the chromaticities of the PC-primary matches were clustered closely together and were centered at a point significantly different from the chromaticity of the reference white. the magnitudes, but not the directions, of the dispersions of the matching chromaticities were consistent with age related changes in the spectral transmission of the lens.     

BoostingTree: parallel selection of weak learners in boosting, with application to ranking

Boosting algorithms have been found successful in many areas of machine learning and, in particular, in ranking. For typical classes of weak learners used in boosting (such as decision stumps or trees), a large feature space can slow down the training, while a long sequence of weak hypotheses combined by boosting can result in a computationally expensive model. In this paper we propose a strategy that builds several sequences of weak hypotheses in parallel, and extends the ones that are likely to yield a good model. The weak hypothesis sequences are arranged in a boosting tree, and new weak hypotheses are added to promising nodes (both leaves and inner nodes) of the tree using some randomized method. Theoretical results show that the proposed algorithm asymptotically achieves the performance of the base boosting algorithm applied. Experiments are provided in ranking web documents and move ordering in chess, and the results indicate that the new strategy yields better performance when the length of the sequence is limited, and converges to similar performance as the original boosting algorithms otherwise.     

Development and characterization of cube-textured Ni–Cu–Co substrates for YBCO-coated conductors

Ni–Cu–Co alloys were studied for the development of textured substrates for YBCO-coated conductor application. Three compositions were obtained by adding a fixed amount of 3 at.% Co to the binary Ni_xCu_100?x, where x = 40, 50 and 60. Cube texture was induced by conventional cold rolling followed by high-temperature annealing. The structural, microstructural, morphological, electrical, magnetic, mechanical and oxidation properties were evaluated and compared with those exhibited by the binary Ni–Cu alloy, as well as by Ni–W and pure Ni. A low Ni content is detrimental for the development of the cube texture with respect to higher concentrations. Nevertheless, the use of high annealing temperatures enabled an area fraction of cube orientation as high as 95% to be obtained for x = 40, and >97.5% in the case of Ni-richer alloys. Compared with Ni and Ni–W, Ni–Cu–Co alloys oxidize more easily and exhibit higher electrical resistance. In addition, the presence of copper enables the Curie temperature to be reduced to 60 K for x = 40 and to 155 K for x = 50. Furthermore, the introduction of cobalt reduces the oxidation rate at temperatures normally used for the deposition of ceramic buffer layers, thus allowing the successful development of a CeO₂/YSZ/CeO₂ architecture on ternary Ni–Cu–Co alloy. YBCO/buffer multilayer architecture deposited by pulsed laser deposition on a selected alloy tape exhibits a critical current density exceeding 1 MA cm^?2 at 77 K in self-field, indicating that this alloy substrate is suitable for YBCO-coated conductor application.     

HOW TO INCREASE THE DRYER EFFICIENCY - LOSS PREVENTION ON A PAPER MACHINE

In order to reduce superfluous energy consumption, the dryer section of an open paper machine was investigated experimentally. The recorded data covered the energy - and mass balances of both the individual drums and the whole dryer section, the state characteristics of the dryer air and some characteristics of the product. In the constant rate period of evaporation the specific heat consumption shows the minimum between 100 1050C dryer surface temperature while the specific evaporation performance is in direct proportion to it. The extent of the increase in energy consumption and of the decrease in evaporation performance below the critical value of moisture content is also demonstrated. Additional possibilities of energy saving exist mainly in aeration and in the more efficient operation of the presses. Some of the results are the characteristics of the investigated machine. It is believed, however, that the results referring to the effect of dryer surface temperature and moisture content are of a general validity and can be applied to other systems as well.     

Lattice QCD as a video game

The speed, bandwidth and cost characteristics of today's PC graphics cards make them an attractive target as general purpose computational platforms. High performance can be achieved also for lattice simulations but the actual implementation can be cumbersome. This paper outlines the architecture and programming model of modern graphics cards for the lattice practitioner with the goal of exploiting these chips for Monte Carlo simulations. Sample code is also given.     

Stereochemische Untersuchungen heterocyclischer Verbindungen. XII. Kristall- und Molekülstruktur von 1-(2-Amino-1-cyano-2-thio-ethylen)pyridiniumyliden

Stereochemical Investigations of Heterocyclic Compounds. XII. Structural Investigations of 1-(2-Amino-1-cyano-2-thio)ethene Pyridinium Ylides Two isomerization processes were found by ¹H-d-n. m. r. characterized by ΔG^* = 67 ± 4 KJ/mol for E- Z-isomerization and ΔG^* = 46 ± 5 KJ/mol for the hindered rotation of the pyridine substituent in 1a . The structure of 1b was solved by direct method. Crystals are monoclinic space group P2₁/n, a = 13.682(3), b = 9.452(1), C = 19.713(6) Å, β = 96.42(2)°, V = 2533.3 ų, D_x = 1.328 Mg · m⁻³, Z = 8. Both E- and Z-isomeres of 2b are found in the crystal lattice. The amino C distance with 1.369 (1,387) Å is shorter than the theoretical single bond distance. The formal  CC double bond with 1.377 (1.391) Å is considerably longer than 1.337 Å observed in the some alkenes.