深基坑工程动态施工反演分析与变形预报

提出了动态施工反演分析的思想，即在常规的反分析过程中引入逐步开挖和逐道支撑的动态施工因素，以求仿真模拟工程实际情况，进而为相继施工阶段的变形预报提供可靠保证。文中基于任意施工阶段间围护墙体变形与内支撑梁轴力的增量测值和施工ＦＥＭ优化反演分析法，反推了各土层的弹性模量系数，给出了作用在墙体两侧的土压力分布，并预报各相继施工阶段的墙体和土体变形、内力及内支撑梁轴力。     

What is the significance of nitrogen-vacancy centers in the doping into diamond?

In order to advance quantum computer after successful synthesis of a qubit (quantum-bit) using a NV (nitrogen-vacancy) center in diamond crystal, the innovation of a NOT processor is strongly demanded. A candidate of it can be one NV center associated with an additional N atom, which is called a NV–N center. Making use of a classical molecular dynamics simulation of N ion implantation into pure diamond with an energy of 200 eV, we have examined the crystallographic structure of “NV–N” centers. However, at low temperature of 30 K, most implanted N atoms became interstitials, thus it was difficult to identify even NV centers.     

Preparation of sharp-melting hard palm midfraction and its use as hard butter in chocolate

Preparation of hard palm midfractions (PMF) and its use as a cocoa butter equivalent ingredient were studied. Hard PMF is obtained by multistep fractionation of palm oil involving dry fractionation (DF) and/or solvent fractionation (SF), usually using hexane or acetone. From our experience, in acetone, a polar solvent, symmetrical 1,3-disaturated triacylglycerols tend to selectively crystallize more than nonsymmetrical 1,2- or 2,3-disaturated triacylglycerols, making it suitable for obtaining the solid midfraction. Unfortunately, triacylglycerols are very soluble in hexane, and temperatures at least 15 degrees lower than those required for acetone must be used for equivalent crystal yields. On the other hand, DF is a less expensive and safer process. Thus, multistep fractionation combining DF and SF using acetone was developed to achieve sufficient removal of high-melting components, and further enrichment of 1,3-dipalmitoyl-2-oleoylglycerol and the hard PMF was obtained by triple-step fractionation of palm olein or double-step fractionation of soft PMF. Compared to conventional hard PMF, this hard PMF had a steeper melting curve and better snapping and sharp-melting qualities when used in chocolate. Heat resistance of the hard PMF chocolate was similar to the conventional hard PMF chocolate, and its bloom resistance could be improved by adding polyglycerol fatty acid esters.     

The mechanism of formation of iron oxide and oxyhydroxides in aqueous solutions at room temperature

For a better understanding of the atmospheric rusting of iron and steels, the present work is aimed to explore the mechanism of formation of green rusts, Fe₃O₄, α-FeOOH, β-FeOOH, γ-FeOOH, δ-FeOOH and amorphous ferric oxyhydroxide in aqueous solution at room temperature. The formation processes on which end products are determined are strongly affected by the oxidation rate, pH and the structure and composition of initial and intermediate species of iron. The systematic diagram of formation processes of iron oxide and oxyhydroxides has been presented, in which both dissolved and solid species of iron are included.     

The mechanism of atmospheric rusting and the protective amorphous rust on low alloy steel

Atmospheric rusting of mild and low alloy steels was studied by means of infra-red and far infra-red spectrophotometries, X-ray and electron diffraction methods and scanning electron microscopy. The rusting process can be interpreted on the basis of a previously reported diagram for rust formation in aqueous solution.A large amount of amorphous matter in rust formed in semi-rural atmosphere was identified by infra-red and far infra-red spectra as amorphous ferric oxyhydroxide, FeO_x (OH)_8–2x. The amorphous ferric oxyhydroxide rust on low alloy steel was dense and uniform, and contained a considerable amount of bound water. From these results it can be concluded that the amorphous ferric oxyhydroxide rust acts as a protective barrier against atmospheric rusting of the steels. Cu, P and Cr in low-alloy steels are inferred to favour the formation of crack-free, uniform rust layer and help to produce uniform amorphous ferric oxyhydroxide.     

X-ray photoelectron spectrum of Fe2+ state in iron oxides

As a standard for identification of iron oxides by X-ray photoelectron spectroscopy, Fe²⁺ spectra are extracted from mixed Fe 2p_3/2 spectra of Fe³⁺, Fe³⁺ and metallic states. The peaks of Fe²⁺ spectra are all located at binding energy of 708·5 eV. The width of Fe²⁺ spectrum seems to be dependent on crystallinity, and is 2·2 eV for a bulk crystalline oxide and 2·9 eV for an amorphous thin film under instrumental condition with FWHM of 1·3 eV for Au 4f_7/2.     

Experimental examination of the characteristics of bright-field scanning confocal electron microscopy images

We experimentally examined the characteristics of bright-field (BF) scanning confocal electron microscopy (SCEM) images by changing the observation conditions and comparing the images with those obtained by BF transmission electron microscopy (TEM) and BF scanning TEM (STEM) modes. The observation of 5-nm-diameter Au nanoparticles demonstrated that BF-SCEM produces object elongation of more than 2000?nm along the optical axis, as do BF-TEM and BF-STEM. We demonstrated the relationship between elongation length and geometric effects such as convergence and collection angles of a probe and the lateral size of an object; the relationship is consistent with previous theoretical prediction. Further, we observed interesting features that are seen only in the BF-SCEM images; the film contrast was strongly enhanced, compared with that of BF-STEM. In addition, a bright contrast appeared around the object position in the elongated images. Using this characteristic, we could determine the object position and structure.     

Simple evaluation of aortic arch calcification by chest radiography in hemodialysis patients

Vascular calcification is associated with a poor prognosis in dialysis patients. It can be assessed with computed tomography but simple inoffice techniques may provide useful information. We compared the results obtained with a simple noninvasive technique with those obtained using multidetector computed tomography for aortic arch calcification volume (AoACV) in chronic hemodialysis (HD) patients. The enrolled study subjects were 63 (32 men and 31 women) maintenance HD patients. Calcification of the aortic arch was semiquantitatively estimated with a AoAC score (AoACS) on plain chest radiology. The AoACV was increased, with a mean value of 6.6 ranging from 0% to 36.5%. The coefficient of intraobserver variation was less than 2.5%. Aortic arch calcification score was highly correlated with AoACV (r=0.635, P<0.001). Multiple regression analysis showed age (F value=12.62, P<0.001) and pulse pressure (F value=4.54, P=0.037) to be significant independent determinants of AoACS. In conclusion, a simple measurement of AoACS may be useful for inoffice imaging to choose a therapeutic regimen in HD patients.     

Effect of anisotropic yield functions on the accuracy of hole expansion simulations

The deformation behavior of 780 MPa grade dual-phase steel sheet subjected to hole expansion is investigated both experimentally and analytically to clarify the effect of the material model (anisotropic yield function) on the predictive accuracy of finite element analysis of hole expansion. Biaxial tensile tests of the material were conducted; contours of plastic work and the directions of plastic strain rates are precisely measured and are in good agreement with those predicted from the Yld2000-2d yield function with an exponent of 4 ( [Barlat et al., 2003] and [Yoon et al., 2004]). Finite element and experimental analyses on the hole expansion of the material were conducted. The Yld2000-2d yield function with an exponent of 4 provides closer agreement with the experimental results than other yield functions. Consequently, the anisotropic yield functions significantly affect the predictive accuracy of the deformation behavior of the steel sheet subjected to hole expansion, and the biaxial tensile test is effective for identification of the appropriate anisotropic yield function to be used for hole expansion simulation.