Low-frequency kinetics of high-T c metal oxides

A microscopic explanation of the low-frequency kinetic properties of metal oxides is proposed. It is based on a strong electron-phonon interaction, which forms a charged Bose liquid of small bipolarons. The large value, the nonKorringa temperature dependence above T _c, and the absence below T _c of the coherent peak of the nuclear spin relaxation, as well as an unexpected coherent peak of the low frequency dynamic conductivity and the linear T-dependence of the resistivity are explained.     

SARFing the PDB

Fast growth of the number of the solved protein structures isincreasing the role of their comparative analysis. In this paperI describe a new program, SARF2, for protein structure comparisonand discuss new examples of the non-topological structural resemblance.SARF2 is designed to detect ensembles of secondary structureelements, which form similar spatial arrangements with possibledifferent topological connections. The program is availableto everyone through the World Wide Web (URL http://wwwhnmb.ncifcrf.gov/{small tilde}nicka/sarf2.html). The performance of the programis demonstrated by previously unnoticed cases of the significantsimilarities. One similarity discussed in this paper, betweenheme-binding proteins (cytochrome P450 and globin), consistsof six -helices, arranged into a globin fold. Another pair ofstructures (pectate lyase and snowdrop lectin) achieve similarß-prism architecture through different topologies.The significance of these similarities is validated by (i) thedistribution of a similarity score, (ii) the comparison of thealigned contact maps and/or (iii) the location of the activesite. The observation of recurrent non-topological structuralmotifs implies their energetic stability and opens new possibilitiesfor sequence-structure alignment (threading) methods.     

Upper critical field of high-T c oxides: Evidence for 2e Bose liquid

We measure and theoretically describe the upper critical field, H_c ²(T), of BSCCO — 2212 crystals with T_c > 92K by the use of the out-of-plane resistivity in magnetic fields (H ab) up to 15T. The empirical procedure is proposed allowing us to extrapolate the H_c ²(T) curve up to H_c ² 230T and t/t _c 0.35 which is independent of the choice of the R/R_N ratio. We found that H_c2(T) does not follow the conventional theory with or without fluctuations and the magnetic scattering, but is consistent with the prediction based on the Bose-Einstein condensation of charged bosons formed aboveT _c . Our results together with several other measurements of H _c 2 and with the heat capacity data provide an evidence for the possibility of 2 _e Base liquid ground state of high-T _c oxides.We highly appreciate the enlightening discussions with Sir Nevill Mott, P. Edwards, J. Cooper, N. Hussey, J. Loram, A. Mackenzie, and K. Ziebeck.     

Effect of constitutive laws on plane strain ideal flow design: an analytical example

Summary. The major objective of this paper is to clarify the effect of constitutive laws on bulk forming design based on the ideal flow theory. The latter theory is in general applicable for perfectly/plastic materials. However, its kinematics equations constitute a closed-form system, which are valid for any incompressible materials, therefore enabling us to extend design solutions based on the perfectly/plastic constitutive law to more realistic laws with rate sensitive hardening behavior. In the present paper, several constitutive laws commonly accepted for the modeling of cold and hot metal forming processes are considered and the effect of these laws on one particular plane strain design is demonstrated. The closed form solution obtained describes a nontrivial nonsteady ideal process. The design solutions based on the ideal flow theory are not unique. To achieve the uniqueness, the criterion that the plastic work required to deform the initial shape of a given class of shapes into a prescribed final shape attains its minimum is adopted. Comparison with a non-ideal process is also made.     

Structural Bases of Prion Variation in Yeast

Amyloids are protein aggregates with a specific filamentous structure that are related to a number of human diseases, and also to some important physiological processes in animals and other kingdoms of life. Amyloids in yeast can stably propagate as heritable units, prions. Yeast prions are of interest both on their own and as a model for amyloids and prions in general. In this review, we consider the structure of yeast prions and its variation, how such structures determine the balance of aggregated and soluble prion protein through interaction with chaperones and how the aggregated state affects the non-prion functions of these proteins.     

Qualitative behaviour of viscoplastic solutions in the vicinity of maximum-friction surfaces

The maximum-friction surface is a source of singular solution behaviour for several rate-independent plasticity models. Solutions based on conventional viscoplastic models do not show such behaviour. For a class of materials, there is a range of temperatures and/or strain rates where a necessity of the consideration of rate effects depends on the area of application of the final result. Hence, the same material under the same conditions can be represented by either rate-independent or rate-dependent models. In this case, a reasonable requirement is that viscous effects should not be very significant and, in particular, the qualitative behaviour of viscoplastic solutions should be similar to that of solutions based on rate-independent models. The present paper deals with this issue by means of the solution for simultaneous shearing and expansion of a hollow cylinder under plane-strain deformation. One of the goals of the paper is to show that there is a class of viscoplastic models satisfying the requirement formulated. The other goal is to find an asymptotic representation of the solution in the vicinity of the maximum-friction surface and compare it with the rigid perfectly plastic solution.     

Microstructure Evolution in a Cu-0.5Cr-0.2Zr Alloy Subjected to Equal Channel Angular Pressing,Rolling or Aging

Journal of Materials Engineering and Performance - The evolution of microstructure in the Cu-0.5%Cr-0.2%Zr alloy subjected to thermomechanical treatment has been studied by means of the x-ray...     

Crystalline quality improvement in silicon films on sapphire using recrystallization from the silicon-sapphire interface

The use of the process of solid-phase recrystallization reduces to a great extent the number of defects in the silicon layer. An amorphous layer was formed by implantation of silicon ions. The crystalline quality of the SOS structures has been assessed by the method of high-resolution double-crystal X-ray diffraction. Silicon layers with a thickness d = 1000–2500 Å and a high crystalline quality have been obtained after implantation of 150-keV silicon ions with subsequent high-temperature annealing.

     

Exploring three-dimensional matrix-assisted laser desorption/ionization imaging mass spectrometry data: three-dimensional spatial segmentation of mouse kidney

Three-dimensional (3D) imaging has a significant impact on many challenges of life sciences. Three-dimensional matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) is an emerging label-free bioanalytical technique capturing the spatial distribution of hundreds of molecular compounds in 3D by providing a MALDI mass spectrum for each spatial point of a 3D sample. Currently, 3D MALDI-IMS cannot tap its full potential due to the lack efficient computational methods for constructing, processing, and visualizing large and complex 3D MALDI-IMS data. We present a new pipeline of efficient computational methods, which enables analysis and interpretation of a 3D MALDI-IMS data set. Construction of a MALDI-IMS data set was done according to the state-of-the-art protocols and involved sample preparation, spectra acquisition, spectra preprocessing, and registration of serial sections. For analysis and interpretation of 3D MALDI-IMS data, we applied the spatial segmentation approach which is well-accepted in analysis of two-dimensional (2D) MALDI-IMS data. In line with 2D data analysis, we used edge-preserving 3D image denoising prior to segmentation to reduce strong and chaotic spectrum-to-spectrum variation. For segmentation, we used an efficient clustering method, called bisecting k-means, which is optimized for hierarchical clustering of a large 3D MALDI-IMS data set. Using the proposed pipeline, we analyzed a central part of a mouse kidney using 33 serial sections of 3.5 μm thickness after the PAXgene tissue fixation and paraffin embedding. For each serial section, a 2D MALDI-IMS data set was acquired following the standard protocols with the high spatial resolution of 50 μm. Altogether, 512?495 mass spectra were acquired that corresponds to approximately 50 gigabytes of data. After registration of serial sections into a 3D data set, our computational pipeline allowed us to reveal the 3D kidney anatomical structure based on mass spectrometry data only. Finally, automated analysis discovered molecular masses colocalized with major anatomical regions. In the same way, the proposed pipeline can be used for analysis and interpretation of any 3D MALDI-IMS data set in particular of pathological cases.     

交流和直流输电线路的经济比较

为比较交直流输电线路的经济性能,首先指出,在采用可控并联电抗器的条件下,交流输电线路的长度和传输功率不受限制。交、直流输电经济比较的准则为线路长度、传输功率、导线功耗和导线电流密度均相同,因此交流相电压应与双极直流的极地电压相等,从而两者的导线重量和价格相同,线路杆塔总的机械负荷和价格亦大体相同,但直流线路的两侧要求设置十分昂贵的换流站和无功能源,故而直流输电的总费用远比交流高;对远距离输电线路常需与中间系统相连的问题,交流线路只用投入联络变压器,而直流线路则需设置代价高昂的换流站。过去人们常将直流极地电压等同于交流相间电压而作对比,得出≥1000km距离时的直流线路要比交流线路更为经济的不适当结论。由于以上主要原因,欧洲国家(包括俄罗斯)不采用架空直流输电线路。