Rectangular Parallelepiped Shape Research Articles

On the resolution of fluorescent spectroscopy in ultrathin gas cells

Theoretical studies have been conducted on sub-Doppler resonances of fluorescence of an ultrathin gas layer in a cell with an internal weakness less than or on the order of the wavelength of a monochromatic light beam incident on the given cell in the normal direction. The features of these resonances are analyzed both under steady-state action of the incident radiation and immediately following abrupt termination of its action. The essential dependence of these resonances (at the centers of optical transitions with sufficiently small radiation spectral linewidths) on the transversal dimensions of the gas cell (using the example of a rectangular parallelepiped shape). The main focus is on analyzing the linear optics case when the examined resonances are narrowest. The possibility is noted of using such sub-Doppler fluorescence resonances in nanometer gas cells as references for optical frequency standards.

Bond strength of Y‐TZP–zirconia ceramics subjected to various surface roughening methods and layering porcelain

AbstractThe interface between yttrium oxide partially stabilized tetragonal zirconia polycrystalline (Y‐TZP) core and veneering porcelain is the site of most clinical failures. Many efforts have focused on increasing the bond strength between Y‐TZP core and veneering porcelain, and such approaches include increasing the surface roughness and providing undercuts. However, each surface roughening method carries limitations. The specific aim of this study was to test the bond strengths of Y‐TZP subjected to different methods (sandblasting, fine polising, and rough polising) and of veneering porcelain. Presintered zirconia blocks with rectangular parallelepiped shape were prepared, and the surfaces were roughened with different methods before sintering. Shear strength of each zirconia–veneer interface was measured from 15 specimens. The surface at the fractured areas after shear test was investigated using an optical microscope. In conclusion, Y‐TZP subjected to sandblasting showed inferior shear strength compared to other groups. Cohesive fracture was observed in the sandblasting group; combination of cohesive and adhesive fracture was observed in the control, fine polishing, and rough polishing groups. Copyright © 2010 John Wiley & Sons, Ltd.

新素材：環境・エネルギー材料の新展開 水溶液中における金属微粉末の合成と形態制御

Metal powders were prepared by precursor—thermal decomposition method and chemical reduction method in aqueous solutions. In precursor—thermal decomposition method, the morphology and size of nickel powder were controlled via the thermal decomposition of nickel oxalate powder, that was prepared by mixing a solution containing oxalic acid ion with some kinds of nickel sources such as nickel ion, ammoniacal nickel complex ion, and nickel hydroxide. Needle-like nickel oxalate powder with high aspect ratio, [Ni(NH3)2]C2O4 2H2O, was synthesized by using ammoniacal nickel complex ion, and rectangular parallelepiped shape of nickel oxalate powder, NiC2O4 2H2O, was by nickel hydroxide. As for the chemical reduction method in aqueous solution, ascorbic acid (vitamin C) at pH 3 reacts with copper ion as a reducing agent, and copper metal particle in size of 100 nm was obtained. Under the condition of pH > 3, reduction property is weakened, and precipitates consisted of copper powder with cuprous oxide. Ti3+ ion (Ti2(SO4)3 solution) also has a reducing property for copper ion and acts as a new reducing agent in liquid phase reduction process.

Assessment of cortical bone density and anisotropy in human femur using ultrasound and x‐ray

The purpose of this research is to investigate the contribution of the intrinsic properties of human bone to the ultrasound velocities in the axial, radial, and tangential directions. Samples of cortical bone were cut from 19 human medial femurs and polished to a rectangular parallelepiped shape. The orientation of apatite crystallites was assessed by microbeam x‐ray diffraction, the density with a densitometer using the Archimedes' principle. Bone mineral density (BMD) was also measured with peripheral quantitative computed tomography (pQCT) and dual‐x‐ray absorptiometry (DXA). The speed of sound (SOS) for each three directions was measured with 3 MHz ultrasonic broadband transducers. Radial and tangential SOS demonstrated a strong correlation with density (R=0.83,p<0.0001 and R=0.85,p<0.0001, respectively). In the axial direction, the correlation between density and SOS was moderate (R=0.59). However, a significant correlation was found by using density and apatite orientation of c‐axis in a multiple re...

Preparation of gold colloid using pyrrole-2-carboxylic acid and characterization of its particle growth

Gold colloid was prepared by reduction of tetrachloroaurate using pyrrole-2-carboxylic acid in the presence of α-methoxy-ω-mercaptoethyl-poly(ethylene glycol). The shape and size of the obtained gold colloids were monitored by absorption spectroscopy and transmission electron microscopy during the reduction reaction. In the early stage of the reducing reaction, large fluffy particles with diameters >100 μm were observed. Some of these large particles had rectangular parallelepiped shapes. However, the mean particle size decreased with increasing time. Eventually, these large, non-round-shaped particles disappeared almost completely, and uniform round-shaped particles with a mean diameter of 10.5 nm became dominant.

Bioinspired Bi2S3 Thin Films on 4-Mercaptobenzoic Acid Functionalized Self-Assembled Monolayers

Self-assembled monolayers (SAMs) of 4-mercaptobenzoic acid (4-MBA) were used to induce the nucleation and growth of bismuth sulfide thin films from aqueous solution at low temperature. The effects of 4-MBA SAMs on the shape, structure, and crystallographic orientation of Bi2S3 crystals were investigated using scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, high-resolution transmission microscopy, and selected area electron diffraction. It was found that Bi2S3 crystals on the 4-MBA SAMs showed a rectangular parallelepiped shape and exhibited completely oriented crystalline domains with [001] directional preferred growth. However, the precipitated Bi2S3 films on the unfunctionalized surface consisted of quasispherical Bi2S3 polycrystalline particles. The mechanism of differences in the crystal properties can be explained by taking into account the liquid growth medium and the effect of 4-MBA SAMs.

Electron Conductive Three-Dimensional Polymer of CuboidalC60

Single crystals of three-dimensional (3D) C60 polymer were prepared by the topotactic conversion of two-dimensional (2D) C60 polymer single crystals at a pressure of 15 GPa at 600 degrees C. The x-ray single crystal study revealed that the 3D C60 polymer crystallized in a body centered orthorhombic space group Immm, and spherical C60 monomer units were substantially deformed to rectangular parallelepiped (cuboidal) shapes, each unit being bonded to eight cuboidal C60 neighbors via [3 + 3] cycloaddition. The 3D C60 polymer was electron conductive, in contrast with the nonconductive behavior of 2D polymers.

Preparation of Size and Aggregation Controlled Nickel Oxalate Dihydrate Particles from Nickel Hydroxide

Abstract. Nickel oxalate nanoparticles as nickel precursor were synthesized from nickel hydroxide (Ni(OH) 2 ) slurry by mixing H 2 C 2 O 4 solution. Precipitates of nickel oxalate dihydrate (NiC 2 O 4 ·2H 2 O) were formed by adding H 2 C 2 O 4 solution of pH 1. The NiC 2 O 4 ·2H 2 O particles with rectangular parallelepiped shape of ca. 440 nm sizes were prepared from the Ni(OH) 2 slurry at 298 K by dropping H 2 C 2 O 4 solution at a rate of 1 ml min -1 . The NiC 2 O 4 ·2H 2 O particles of rectangular parallelepiped shape were formed at 298-333 K, and was finely dispersed without aggregation. The size of the particle was controllable by preparation temperature. Introduction Interest in synthesizing nickel nanoparticles has increased considerably in recent years, largely in line with its growing applications such as magnetic recording medium, battery, internal electrodes of multi-layer ceramic capacitors and so on. The size and morphology control of nanoparticles is very important for their use in nanotechnology applications. A number of methods are considered for preparing nickel particle. Main methods of preparation, however, have so far been chemical reduction procedures and decomposition of metal carbonyl nickel compounds. In particular, the chemical reduction in aqueous system can prepare only a spherical nanoparticle, but the aggregation of particles is often serious [1-6]. We developed fabrication process of nickel nanoparticle to control the morphology and size. The process consists of two-step, i.e., synthesis of nickel oxalate as nickel precursor by precipitation reaction between nickel ammoniate ion, and oxalate ion and thermal decomposition of the nickel oxalate precursor. The morphology of the precursor is controllable as rectangular parallelepiped shape, rod-like, and needle-like by controlling coordination number of nickel ammoniate ion [7]. Then, needle-like nickel particle is obtained by the heat treatment of the needle-like precursor under inert atmosphere [8]. The main part of this process is morphology and size controls of nickel oxalate precursor, because those of the precursor determine the morphology and size of final products. In the preparation of nickel oxalate precursor in aqueous solution, aggregation of the

The role of molecular mechanics in intracellular signaling: Mechanisms and models

The study concerns the determination of mechanical properties of human coronary arterial walls with both experimental and constitutive modeling approaches. The research material was harvested from 18 patients (range 50-84 years). On the basis of hospital records and visual observation, each tissue sample was classified according to the stage (0, I, II, III) of atherosclerosis development (SAD). Then, strip samples considered as a membrane with the shape of rectangular parallelepiped were preconditioned and subjected to uniaxial tensile tests in longitudinal (n=27) and circumferential (n=4) direction. With experimental data obtained, the stress-strain characteristics were prepared. Furthermore, tensile strengths and related strains, stiffness coefficients and tangent modules of elasticity were computed. For a constitutive model of passive mechanical behavior of coronary arteries, values of material parameters were computed. The studies led to the following conclusions. Most importantly, the atherosclerotic changes affect all the mechanical properties of arterial walls. A progress of arteriosclerosis contributes to an increase of vascular stiffness. The highest values of the stiffness coefficients are obtained for the tissues in the advanced stage of the disease. We were also able to observe that gradual calcification, progression of atherosclerosis and degradation of collagen in the tissue caused a decrease of tensile strengths and related strains. Finally, a comparison made for the tissues with the advanced SAD showed that the tensile strengths and strains were much higher in the case of the samples with the circumferential orientation rather than those with the longitudinal one.

A hybrid finite element-analytical method for determining the intrinsic elastic moduli of particles having moderately extended shapes and a wide range of elastic properties

The presence of a low (dilute) concentration of particulate inclusions having any shape and any property mismatch with the matrix in which they are placed, influences the elasticity of the resulting composite material. This influence is via the intrinsic moduli, which characterize the first-order term in an expansion of the effective properties in terms of the volume fraction of inclusions. The intrinsic moduli have only been solved exactly for general property mismatch in the case of ellipsoidal particles, and are analytically intractable for more general geometries. The problem of computing intrinsic elastic moduli for general geometries is approached by combining exact information that is known from analytical theory with numerical finite element computations to obtain an approximate analytical description of the intrinsic bulk ( K) and shear ( G) moduli of the particles as a function of shape and matrix and inclusion elastic properties. The approximant analytical equations are developed for a wide range of isotropic elastic property ( K, G, and Poisson’s ratio) mismatch with the matrix and a modest range in shape, so that these approximants should be useful in characterizing property changes in real composite materials (e.g., concrete and polymer nanocomposites) to which a dilute concentration of particles have been added. Particular emphasis is given in this initial study to particles having a rectangular parallelepiped shape.

Thermal Behavior of Prismatic Lithium-Ion Battery during Rapid Charge and Discharge Cycles

The temperature of secondary batteries may increase above allowable limits and deteriorate its performance, during rapid charge and discharge cycles. Therefore, assessing thermal behavior of battery is essential. On the other hand, rectangular parallelepiped shape batteries are supposedly going to be used more commonly for cars and electrical devices because of their better space efficiency. Then, we constructed a two dimensional Cartesian coordinates battery thermal behavior model for a prismatic lithium-ion secondary battery during rapid charge and discharge cycles. It was extended from one dimensional cylindrical coordinates model, which had been developed and experimentally verified. As parameters of the numerical model, battery heat source factors such as overpotential resistance, entropy change, heat transfer coefficient and heat capacity have been measured. The radiation thermometer was used for obtaining battery surface temperature variance and distributions. Battery temperature generally increases as charge and discharge cycle proceeds, nevertheless temperature drops were observed at begging of low rate charge cycle and vicinity of SOC=0.8 in discharge cycle. Our modified model could predict these phenomena and agreed well with experimental results. Then the reliability of our numerical model and measuring techniques of heat source factors are confirmed each other.

Raising the sensitivity of the electron-paramagnetic-resonance spectrometer using a ferroelectric resonator

In order to raise the sensitivity of microwave electron-paramagnetic-resonance (EPR) spectrometers, it is proposed to use a piece of ferroelectric material as an additional resonator. The method has been tested using the RE-1307 microwave EPR spectrometer and a pulsed microwave spectrometer. The possibility of raising the signal-to-noise ratio when using ferroelectric resonators of rectangular-parallelepiped and spherical shape has been considered. For a potassium-tantalate ferroelectric resonator of rectangular-parallelepiped shape, the signal-to-noise ratio has been raised by a factor of 16 at 331 K and by a factor of 10 at 292 K. In the pulse experiment, the presence of the ferroelectric resonator permits a reduction in microwave power, required for sample saturation, by a factor of 50 at 50 K.

X-ray diffuse scattering from extended microdefects of orthorhombic symmetry for Si single crystals

The displacement field of a crystal lattice, in the continuous media approximation, caused by extended microdefects of rectangular parallelepiped shape, is considered. X-ray diffuse scattering from the defect core as well as the long-range displacement field is analyzed. A theoretical expression for the intensity of X-ray diffuse scattering resulting from randomly distributed microdefects of orthorhombic symmetry is presented using the kinematical approximation of X-ray statistical diffraction theory. The computer simulations of the isointensity contours for two sets of defect parameters are performed. A way of obtaining the defect parameters by fitting the computer simulations to the experimental data is proposed.

ＹＡＧレーザによる微細グラファイト電極の成形に関する研究

This paper deals with machining methods of fine graphite electrode for EDM by Q-switched Nd: YAG laser. Graphite is a superior material as an electrode for EDM and has widely been used. However, it is difficult to make a complicated shape of thin graphite plate less than 1mm by the conventional machining methods because of its brittleness. In this paper, Q-switched Nd: YAG laser is used for machining the micro rectangular parallelepiped graphite electrode whose thickness is 0.35mm.Main conclusions obtain are as follows:1. The rectangular parallelepiped whose sections is about 0.35mm square can be machined precisely by Q-switched YAG laser.2. Cutting off method of 2 plates of workpieces together leads to a better rectangular parallelepiped shape of the lower plate.3. The roughness of machined surface is improved by another scanning with lower power laser.4. In normal polarity EDM with RC circuit in deionized water, a better rectangular hole can be generated with copper impregnated graphite electrode.

Compressibility of polycrystal and monocrystal copper: Acoustic-resonance spectroscopy

Using a method used mainly by geophysicists for small specimens-acousticresonance spectroscopy (ARS)-we measured the elastic-stiffness constants of centimeter-size copper specimens with rectangular-parallelepiped shapes. The polycrystal consisted of heavily twinned 75-μm crystallites. From the specimens' macroscopic resonance-vibration frequencies (midkilohertz to low-megahertz), we calculated the least-squares elastic-stiffness coefficients, two and three for the two cases. Using the same specimens, we augmented the ARS measurements with conventional pulse-echo-method measurements. Using rod specimens, we measured the Young modulus E and torsional modulus G, and we calculated the bulk modulus B. The less direct and less familiar ARS method gives the same results as a usual pulse-echo method and a rod-resonance method. The small difference between polycrystal and monocrystal values may arise from mobile twin boundaries that contribute a small reversible plastic strain to the intrinsic elastic strain. We list 16 advantages of the ARS method to measure elastic constants.

Preparation of Bulky Zr-Based Amorphous Alloys by a Zone Melting Method

A bulk amorphous Zr60Al10Ni10Cu15Pd5 alloy was prepared by the zone melting method using an arc-type heat source. The bulk amorphous alloy prepared on the copper hearth has a rectangular parallelepiped shape with a thickness of 10 mm, a width of 12 mm and a length of 170 mm. A majority of the region except the bottom and side edge regions contacted with copper hearth consists of an amorphous phase. The cooling rate achieved by the zone melting method is high enough to cause an amorphous phase in the Zr-based alloy where heterogeneous nucleation is suppressed. The amorphous phase subjected to continuous heating exhibits a distinct glass transition, followed by a wide supercooled liquid region and then an exothermic peak due to crystallization. The success of producing the bulk amorphous alloys by the zone melting method implies the possibility of the continuous production of the bulk amorphous alloys and seems to accelerate the subsequent progress of amorphous alloys.

Subsonic aerodynamics of rectangular parallelepiped shapes of fineness ratio of one-half

Results from static and dynamic stability wind-tunnel tests at subsonic speeds are presented for rectangular cylinders having a fineness ratio of about one-half. Aerodynamic data were obtained over ranges of angles of attack and roll sufficient to construct aerodynamic inputs to a six-degree-of-freedom re-entry simulation for the full rotational motion experienced by a free-falling body. The effects of Reynolds number, edge roundness, angle of attack, and roll angle were investigated. Free-fall tests of the model are also described. The aerodynamic characteristics were found to be highly nonlinear with the various geometric and flow variables investigated, especially at attitudes near broad face and narrow side to the wind.

LARGE SCALE MODEL TESTS OF PLACED STONE BREAKWATERS

Large scale model studies reveal that Reynolds scaling can affect the apparent stability and wave modifying properties of layered breakwater structures. Results of a study for a breakwater configuration designed to protect offshore power and port facilities in water depths to 60 feet are presented and discussed. The armor layer of this structure is formed from quarried rock of irregular rectangular parallelepiped shape, individually placed perpendicular to 1:2 seaward slope and crest. The resulting armor layer is relatively smooth, densely packed and very stable. Model studies of similar configurations were studied at 1:10, 1:20 and 1:100 scale ratios. Stability, runup, rundown and reflection were measured for a variety of water depths, wave heights and periods. Analysis of the large scale test results establish that the placed stone armor is approximately as stable as dolos armor units. Runup, rundown and reflection respond similar to rough, impermeable slopes. Comparison of large and small scale results demonstrate that relative increases in drag forces at lower Reynolds numbers decrease stability and runup in small scale models.