Low-field positive and high-field negative magnetoresistances in multiphase Fe-oxide thin films at room temperature

Multiphase Fe-oxide thin films are fabricated on glass substrates by a facing-target sputtering tech- nique. X-ray diffraction and X-ray photoelectron spectroscopy reveal that Fe, Fe3BO4, γ -Fe2BO3B and FeO coexist in the films. High resolution transmission electron microscopy shows the well-defined colum- nar grain structure with the unoxidized Fe as the core and iron-oxide as the shell. The low-field positive and high-field negative magnetoresistances coexist in such a system at room temperature, which can be explained by considering a shell/core model. Nonlinear current-voltage curve and photovoltaic effect further confirm the tunneling-type conduction.     

Relationship between plant species diversity and patch characteristics in a marsh in the Sangjiang Plain, China —Using Yaluhe farm as an example

Based on Quick Bird satellite image data, the present study examined small-scale herbaceous community patches in the marsh of the Sanjiang Plain and measured patch characteristics such as the area, perimeter and shape by GPS. The coenological characteristics of the patches were investigated using quadrat method, and the vascular plant species were recorded using transect method. A total of 219 plant species were recorded, which represents 12.2% of the vascular flora in Heilongjiang Province. Our results showed that species number S correlated with patch area and perimeter; richness index (R) correlated with patch perimeter; Simpson index (D) correlated with patch area and perimeter/area; Shannon-Wiener index (H′) correlated with patch area, perimeter and perimeter/area; Evenness index (Jsw) correlated with perimeter/area. Both S and R have significant difference between different size of patches. Plant diversity in the small-scale herbaceous communities tended to increase with the patch area and perimeter. We concluded that edge effects and the habitat heterogeneity of the patches are important in determining the number of species. The relative smoothness of the patch edges also affects the plant diversity of the patches. The richness of plant species in the marsh in the Sanjiang Plain is highly sensitive to the small-scale patches, which continues to play an important role in preserving plant diversity in the local area.     

Numerical research on the 3D fiber orientation distribution in arbitrary planar flows

The fiber orientation distribution in a fiber suspension flow was investigated by a finite difference scheme in spherical coordinates. The diffusivity was transformed between Cartesian and spherical coordinates through tensor analysis to obtain efficiency. It is found that under simple shear flow condition the diffusivity in the azimuthal direction, Dr, has greater effect on the orientation distribution than that in the colatitude direction, Drθθ.     

Relationship between plant species diversity and patch characteristics in a marsh in the Sangjiang Plain,China—Using Yaluhe farm as an example

Based on Quick Bird satellite image data, the present study examined small-scale herbaceous community patches in the marsh of the Sanjiang Plain and measured patch characteristics such as the area, perimeter and shape by GPS. The coenological characteristics of the patches were investigated using quadrat method, and the vascular plant species were recorded using transect method. A total of 219 plant species were recorded, which represents 12.2% of the vascular flora in Heilongjiang Province. Our results showed that species number S correlated with patch area and perimeter; richness index (R) correlated with patch perimeter; Simpson index (D) correlated with patch area and perimeter/area; Shannon-Wiener index (H′) correlated with patch area, perimeter and perimeter/area; Evenness index (Jsw) correlated with perimeter/area. Both S and R have significant difference between different size of patches. Plant diversity in the small-scale herbaceous communities tended to increase with the patch area and perimeter. We concluded that edge effects and the habitat heterogeneity of the patches are important in determining the number of species. The relative smoothness of the patch edges also affects the plant diversity of the patches. The richness of plant species in the marsh in the Sanjiang Plain is highly sensitive to the small-scale patches, which continues to play an important role in preserving plant diversity in the local area.     

Application of ANSYS 3D FEM in Studies of Surface Deformation Caused by Pipe Jacking

By using site observation data and establishing 3D model using ANSYS software,this paper has discussed the strain change of stratum stress during process of jacking-in and the im-pact of machine head on ground surface under different frontal resistances. Analysis of the two cases shows that soil pressure reaches its maximum point when the soil is right above machine head,and soil stress will gradually decline when machine head passes over it. It also shows that impact brought by pipe-jacking construction on stress change of the surrounding soil is limited. The thesis suggest that road surface should be consolidated and soil condition be improved before construction to prevent loss and disaster caused by road surface deformation,jacking force can be increased so that jacking efficiency can be enhanced when ground stratum is well filled with soil,but the frontal resistance facing machine head should be equal to surrounding soil pressure in order to avoid rise of ground surface.     

Rare earth effects on high temperature oxidation of pure nickel at 1000 ℃

Isothermal and cyclic oxidation behaviors of pure and yttrium-implanted nickel were studied at 1000 ℃ in air.SEM and TEM were used to examine the oxide scales formed on nickel substrate.It was found that Y-implantation greatly improved the anti-oxidation ability of nickel both in isothermal and cyclic oxidizing experiments.Acoustic emission(AE)technique was used to study the size and number distribution of defects at the oxide/metal interface.Laser Raman microscopy was also used to study the stress status of oxide scales formed on nickel with and without yttrium.The main reason for the improvement in anti-oxidation and adhesion of oxide scale was that Yimplantation greatly reduced the grain size of NiO and lowered the compressive stress within the scale.In the meantime,Y-implantation inhibited ion diffusion rate in the oxide scale and reduced the size and number of interfacial defects,hence remarkably enhanced the adhesion of protective NiO oxide scale formed on nickel substrate.     

Enhancing thermoelectric performance of Cu-modified Bi0.5Sb1.5Te3 by electroless plating and annealing

With the capacity of energy conversion from heat to electricity directly, thermoelectric materials have been considered as an alternative solution to global energy crisis. In this work, Cu modified Bi_(0.5)Sb_(1.5)Te_3(BST)composites are prepared by a facile electroless plating Cu method, spark plasma sintering, and annealing. The annealed 0.22 wt.%Cu/BST has an enhanced peak Figure of Merit(z T) of ~ 0.71 at 573 K with high average z T of0.65 in the wide temperature range between 300 and 573 K. Due to the significant increase of electrical conductivity and low lattice thermal conductivity, the annealed 0.22 wt.%Cu/BST shifts peak z T to high temperature, and shows 492% enhancement than that of pristine BST with z T of 0.12 at 573 K. Through detailed structural characterization of the annealed 0.22 wt.%Cu/BST, we found that Cu can dope into BST matrix and further form Cu2 Te nanoprecipitates, dislocations, and massive grain boundaries, leading to a low lattice thermal conductivity of 0.30 Wm-1 K-1 in the annealed 0.22 wt.%Cu/BST. Such enhanced peak z T in high-temperature and high average z T in the wide temperature range shows that the electroless plating Cu method and annealing can improve the thermoelectric performance of commercial BST and expand the applicability of Bi_2Te_3 thermoelectric materials in the power generations.     

Low complexity power control approach based on MMSE detection for V-BLAST

1. INTRODUCTION Layered Space-Time (LST) architecture offers a great increase in capacity, promising a linear growth with the size of the antenna array under some circumst- ances[1,2]. In recent years, Vertical Bell Lab Layered Space-Time (V-BLAST), one of the most important LST architectures, has been a hotspot in mobile com- munication because of its simple architecture and high spectral efficiency [3]. There have been some effective Per-Antenna Po- wer Control (PAPC) algorit…     

Real ribozymes suggest a relaxed error threshold

The error threshold for replication, the critical copying fidelity below which the fittest genotype deterministically disappears, limits the length of the genome that can be maintained by selection. Primordial replication must have been error-prone, and so early replicators are thought to have been necessarily short. The error threshold also depends on the fitness landscape. In an RNA world, many neutral and compensatory mutations can raise the threshold, below which the functional phenotype, rather than a particular sequence, is still present. Here we show, on the basis of comparative analysis of two extensively mutagenized ribozymes, that with a copying fidelity of 0.999 per digit per replication the phenotypic error threshold rises well above 7,000 nucleotides, which permits the selective maintenance of a functionally rich riboorganism with a genome of more than 100 different genes, the size of a tRNA. This requires an order of magnitude of improvement in the accuracy of in vitro-generated polymerase ribozymes. Incidentally, this genome size coincides with that estimated for a minimal cell achieved by top-down analysis, omitting the genes dealing with translation.     

离子晶体量子线中的非线性极化激元

讨论了离子晶体量子线中的非线性极化激元的色散关系。由于量子线对电磁波场的尺寸限制作用及原胞中离子间的非线性相互作用，使离子晶体量子线中的非线性极化激元的色散关系相对于体材料有2点值得注意：在ωTO以下及ωLO以上区域，在波矢k小的区域，频率值向上移动，在原频率禁区ωTO＜ω＜ωLO中，由于非线性效应引起的新的极化激元的频率分支则与体材料基本一致，即尺寸效应不显著，这意味着在量子线中会有与体材料中相同的光孤立子的传输特性。