Protein Adsorption on Hydroxyapatite Nanosensors with Different Crystal Sizes Studied In Situ by a Quartz Crystal Microbalance with the Dissipation Method

Hydroxyapatite (HAp) nanocrystals with different crystal sizes were deposited by the electrophoretic deposition method on the gold surface of a quartz crystal microbalance with a dissipation probe. The nanosensors formed this way were used to elucidate the adsorption mechanism of proteins with a similar pI value. The crystal sizes and the area of the a -plane affected only the adsorption amount of human serum albumin, but not that of bovine plasma fibrinogen. The viscoelastic property, Δ D/ Δ f , of each absorbed layer on the nanosensors was almost constant. The protein adsorption mechanism can be explained as follows: the dissociated carboxyl groups (negative charge) of albumin were interacted with calcium ions and the hydrated amine groups (positive charge) at the αC domain of fibrinogen were with phosphate ions on the HAp surface.     

日建设计的建筑信息模型及其工作方式

如今,日建设计正在积极地提倡使用建筑信息模型(简称BIM)。这种三维的设计方式使我们能够为当今时代尝试各种可能的客户设计出高性能的建筑。BIM可以被解释为一个"三维建筑数据库",它不仅包括三维体量(立方体、圆柱体等)的信息,还包括像梁、柱这样的结构部分,以及造价和许多其他类型的数据。这种设计方式可能很难从直观上掌握,下文中对它的一些特性和程序进行的重点分析,将有助于我们的理解:     

Characterization of an insertion sequence-like element,ISBlo15, identified in a size-increased cryptic plasmid pBK283 in Bifidobacterium longum BK28

The characteristics of mobile genetic elements in bifidobacteria are not well understood. We characterized an insertion sequence-like element of the IS200/IS605 family found in a size-increased cryptic plasmid in Bifidobacterium longum. During a plasmid profile analysis of B. longum BK strains, we encountered a 6.5-kbp cryptic plasmid pBK283 in B. longum BK28, the size of which has not been identified in bifidobacteria. Nucleotide sequence analysis indicated that an insertion sequence-like element was inserted into the 5.0-kbp pKJ50-like plasmid and resulted in a size increase of pBK283. The element, named ISBlo15, was 1593 bp in length and contained a single ORF encoding a putative transposase, which is similar to the transposase OrfB encoded by IS200/IS605 family elements. Several sequence characteristics, including conserved transposase motifs in OrfB and terminal palindromic sequences that differ from the typical terminal inverted repeats, strongly suggested that ISBlo15 is a member of the IS200/IS605 family. Sequences similar to ISBlo15 were widely distributed among the nine Bifidobacterium species tested, and those of highly homologous sequences were detected only in Bifidobacterium gallicum JCM8224^T.     

Micromorphological effect of calcium phosphate coating on compatibility of magnesium alloy with osteoblast

Abstract

Octacalcium phosphate (OCP) and hydroxyapatite (HAp) coatings were developed to control the degradation speed and to improve the biocompatibility of biodegradable magnesium alloys. Osteoblast MG-63 was cultured directly on OCP- and HAp-coated Mg-3Al-1Zn (wt%, AZ31) alloy (OCP- and HAp-AZ31) to evaluate cell compatibility. Cell proliferation was remarkably improved with OCP and HAp coatings which reduced the corrosion and prevented the H₂O₂ generation on Mg alloy substrate. OCP-AZ31 showed sparse distribution of living cell colonies and dead cells. HAp-AZ31 showed dense and homogeneous distribution of living cells, with dead cells localized over and around corrosion pits, some of which were formed underneath the coating. These results demonstrated that cells were dead due to changes in the local environment, and it is necessary to evaluate the local biocompatibility of magnesium alloys. Cell density on HAp-AZ31 was higher than that on OCP-AZ31 although there was not a significant difference in the amount of Mg ions released in medium between OCP- and HAp-AZ31. The outer layer of OCP and HAp coatings consisted of plate-like crystal with a thickness of around 0.1 μm and rod-like crystals with a diameter of around 0.1 μm, respectively, which grew from a continuous inner layer. Osteoblasts formed focal contacts on the tips of plate-like OCP and rod-like HAp crystals, with heights of 2–5 μm. The spacing between OCP tips of 0.8–1.1 μm was wider than that between HAp tips of 0.2–0.3 μm. These results demonstrated that cell proliferation depended on the micromorphology of the coatings which governed spacing of focal contacts. Consequently, HAp coating is suitable for improving cell compatibility and bone-forming ability of the Mg alloy.     

Burning of MOX fuels in LWRs; fuel history effects on thermal properties of hull and end piece wastes and the repository performance

The thermal impacts of hull and end piece wastes from the reprocessing of MOX spent fuels burned in LWRs on repository performance were investigated. The heat generation rates in MOX spent fuels and the resulting heat generation rates in hull and end piece wastes change depending on the history of MOX fuels. This history includes the burn-up of UO₂ spent fuels from which the Pu is obtained, the cooling period before reprocessing, the storage period of fresh MOX fuels before being loaded into an LWR, as well as the burn-up of the MOX fuels. The heat generation rates in hull and end piece wastes from the reprocessing of MOX spent fuels with any of those histories are significantly larger than those from UO₂ spent fuels with burn-ups of 45 GWd/THM. If a temperature below 80°C is specified for cement-based materials used in waste packages after disposal, the allowable number of canisters containing compacted hull and end pieces in a package for 45 and 70 GWd-MOX needs to be limited to a value of 0.4–1.6, which is significantly lower than 4.0 for 45 GWd-UO₂.     

Thermoelastic analyses of cladding on beam transient of lead–bismuth cooled accelerator-driven system

The thermoelastic analyses of cladding for lead–bismuth cooled accelerator-driven system (ADS) are conducted for the beam transients. The beam transients are considered to be caused by the abnormal behavior of the accelerator and are peculiar to ADS. The program of the thermoelastic analyses is developed for the evaluation of the stresses of the cladding. This program is intended to analyze a fuel pin of a cylindrical model, and solves the thermoelastic problem by the use of the finite-element-method. The beam transients are analyzed by employing the ADS dynamic calculation code and the program of the thermoelastic analyses for the ADS designed by Japan Atomic Energy Agency. As a result, the transformation of the beam shape does not cause the cladding failure. However, the ductile failure is caused by the beam incident position change in several seconds. These results are also compared with those of the creep analyses conducted in the previous study, and both the creep and the ductile failure are revealed to be caused by the beam incident position change. Consequently, the beam incident position change is concluded to have a high risk of cladding failure.     

Faecal fermentation of partially hydrolyzed guar gum

Partially hydrolyzed guar gum (PHGG) remains undigested in the upper gastrointestinal tract, but is fermented by bacteria in the large intestine to stimulate short-chain fatty acids, particularly butyric acid. In this study, the bacterial composition in the in vitro faecal fermentation of PHGG was analyzed by real-time PCR to identify the bacteria contributing to the stimulation of butyric acid production. The production of short-chain fatty acids in a PHGG culture was compared with that in inulin and blank (no substrate) cultures. After the fermentation of the substrates by fresh human faeces, PHGG clearly promoted the production of butyric acid. The butyryl-CoA CoA-transferase gene copy number and the 16S rRNA gene copy number of the Roseburia/Eubacterium rectale group in the PHGG culture were significantly higher than those in the blank culture. These results indicated that Roseburia/E. rectale group bacteria would play an important role in the butyric acid production in vitro fermentation of PHGG.     

Development of externally pressurized small-size conical-shaped gas bearings for micro rotary machines

We have developed externally pressurized small-size conical shaped gas bearings for micro rotary machines such as gas blowers, compressors, and medical devices. The bearings are lightweight and enable machines and devices to be downsized by reducing the number of parts, since the journal and thrust loads can be supported by a pair of bearings. The conical bearings (diameters 8 mm and 10 mm) were designed and the manufacturing techniques were considered. The bearing type is a double-row inherent orifice bearing with four feed holes per row. The shape accuracy of the manufactured bearings is within the design limits, being less than 0.005 mm in both roundness and cylindricity. The surface roughness (arithmetic average roughness) of the parts is 0.0002 mm. The static characteristics were calculated and validated by testing on manufactured bearings. Comparative agreement was obtained between the measured and designed values. The proposed calculation method presents as a relatively simple approach for predicting the bearing characteristics. The test rotor exceeded 350 Hz (21,000 rpm) in the rotational test, and whirl vibration was absent. During testing, the maximum rotor vibration amplitude was 0.0125 mm (corresponding to an eccentricity ratio of 0.89).     

An artificial nonradiative recombination center model created by use of a Si1 − xGex/Si quantum-well-inserted pseudomorphic superlattice

An attempt is made to mimic a system under the influence of nonradiative recombination (NR) by use of a Si_1 − xGe_x quantum well (QW) embedded in a Si_1 − xGe_x/Si strained-layer superlattice. Carrier transfer mediates the coupling between the first miniband of superlattice barrier and QW ground state, which is useful in setting up an artificial NR center based only on radiative channels. Steady-state and transient photoluminescence (PL) reproduces spectroscopic features shared by NR systems at large such as quadratic dependence of PL intensity on excitation power and prolonged decay time at increased pumping, which are quite opposite to radiative recombination.     

Synthesis of high concentration colloid solution of silica-coated AgI nanoparticles

Methods for high concentration silica-coated silver iodide (AgI/SiO2) particles, which could be practically used as X-ray contrast agent, were examined. The first was a single-step method, which was to prepare AgI nanoparticles at an AgI concentration of 5 x 10(-3) M and coat the AgI nanoparticles with silica shell by a St?ber method. The second was a multiple-step method, which was to repeat a step for preparing a AgI/SiO2 particle colloid solution with 10(-3) M AgI 5 times for adjusting a final AgI concentration to 5 x 10(-3) M. In the two methods, dominant particle aggregation took place, though core-shell particles were also produced. The third was a salting-out method, which was to salt out AgI/SiO2 particles in their colloid solution prepared at an AgI concentration of 10(-3) M, remove supernatant by decantation, and redisperse the particles in a fresh solvent. Consequently, AgI/SiO2 particles with an AgI concentration as high as 0.05 M were successfully prepared with the salting-out method, and their core-shell structure was not damaged during the salting-out.