Sintering mechanism of hydroxyapatite by addition of lithium phosphate

The sintering mechanism of hydroxyapatite (HAp) by addition of lithium phosphate (Li₃PO₄) has been investigated. Using the X-ray diffraction method, HAp was confirmed to decompose into -Ca₃(PO₄)₂ (-TCP) by addition of Li₃PO₄. The measurement of shrinkage rate by the isothermal firing made it clear that the densification process at the initial stage of sintering took place in the presence of liquid phase. Furthermore, the examination of the phase diagram on the binary system -TCP-Li₃PO₄ revealed that there was an eutectic point at 1010°C in the composition of 60 wt% Li₃PO₄. From these evidences, we concluded that -TCP produced by the decomposition of a part of HAp has formed the liquid phase by reacting with Li₃PO₄ above 1010°C, and that this liquid phase has largely promoted the densification by the rearrangement of HAp particles at the initial stage of sintering.     

Development of smart composite structures with small-diameter fiber Bragg grating sensors for damage detection: Quantitative evaluation of delamination length in CFRP laminates using Lamb wave sensing

The authors and Hitachi Cable, Ltd. have recently developed small-diameter optical fiber and its fiber Bragg grating (FBG) sensor for embedment inside a lamina of composite laminates without strength reduction. The outside diameters of the cladding and polyimide coating are 40 and 52 μm, respectively. First, a brief summary is presented for applications of small-diameter FBG sensors to damage monitoring in composite structures. Then, we propose a new damage detection system for quantitative evaluation of delamination length in CFRP laminates using Lamb wave sensing. In this system, a piezo-ceramic actuator generates Lamb waves in a CFRP laminate. After the waves propagate in the laminate, transmitted waves are received by an FBG sensor attached on or embedded in the laminate using a newly developed high-speed optical wavelength interrogation system. This system was applied to detect interlaminar delamination in CFRP cross-ply laminates. When the Lamb waves passed through the delamination, the amplitude decreased and a new wave mode appeared. These phenomena could be well simulated using a finite element analysis. From the changes in the amplitude ratio and the arrival time of the new mode depending on the delamination length, it was found that this system could evaluate the delamination length quantitatively. Furthermore, small-diameter FBG sensors were embedded in a double-lap type coupon specimen, and the debonding progress could be evaluated using the wavelet transform.     

Swarm robotic network using Lévy flight in target detection problem

One approach in swarm robotics is homogeneous system which is embedded with sensing, computing, mobile and communication components. In this study, a target detection problem, which is one of navigation problems, was employed. Once a robot detects a target, robots immediately communicate with a base station via intermediate relay robots due to the multi-hop transmission of wireless communication. Therefore, this control task is completed with connectivity of the network. In a target detection problem, we must improve the performance of exploration as well as connectivity of the network. This study investigates the performances of the two types of random walk algorithm in navigation while loosely ensuring connectivity of the robotic network based on our previous study.     

Sonochemical decomposition of perfluorooctane sulfonate and perfluorooctanoic acid

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are shown to be globally distributed, environmentally persistent, and bioaccumulative. Although the toxicities of these compounds were reported, the cleanup procedure from the environment is not developed because of their inertness. In this report the sonochemical degradations of PFOS and PFOA to the products through the fission of the perfluorocarbon chains were observed and the half-life times of the PFOS and PFOA degradations under an argon atmosphere determined to be 43 and 22 min, respectively. The shortening of perfluorocarbon chain of PFOS and PFOA leads to the lowering of the toxicity in view of the decrease of the persistence, and the technique would contribute to the remediation of the environmental pollution by these compounds.     

Determination of age-related changes in the morphological structure (sagging) of the human cheek using a photonumeric scale and three-dimensional surface parameters

The usefulness of the photo standard for evaluating skin sagging in the face, especially in the cheeks, was evaluated. A six-stage photo standard was prepared using photos of women aged 17-83-years-old at three magnification rates (136-188 women in each group). Based on this photo standard, scoring was performed using a six-grade scoring system by two specialists to obtain the consensus score. Scoring was also performed in parallel by five general observers. The degree of agreement between the two scores was evaluated by calculating the Kappa value. In each group, the Kappa value was 0.452-0.563, indicating moderate agreement. Thus, the photo standard may be useful for evaluating sagging. Based on the photo standard, a score of 2, at which sagging becomes detectable appeared at the age of 40 years. In parallel, 3D analysis of replicas around the cheek was performed to morphologically analyse age-related changes in sagging. When the depth parameter was compared between the nasolabial groove and the mouth corners, a higher value was observed in the nasolabial groove until the age of 40 years, but higher values were seen in the mouth corners thereafter. This may have been because sagging in the cheeks descends to the area around the mouth, resulting in reversion in the sWv value. These findings indicated that sagging in the cheeks becomes morphologically distinct in women in their forties.     

Enhanced Development of Azoxymethane-Induced Colonic Preneoplastic Lesions in Hypertensive Rats

Metabolic syndrome is associated with an increased risk of colorectal cancer. This study investigated the impact of hypertension, a component of metabolic syndrome, on azoxymethane (AOM)-induced colorectal carcinogenesis using SHRSP/Izm (SHRSP) non-diabetic/hypertensive rats and SHRSP.Z-Lepr^fa/IzmDmcr (SHRSP-ZF) diabetic/hypertensive rats. Male 6-week-old SHRSP, SHRSP-ZF, and control non-diabetic/normotensive Wister Kyoto/Izm (WKY) rats were given 2 weekly intraperitoneal injections of AOM (20 mg/kg body weight). Two weeks after the last injection of AOM, the SHRSP and SHRSP-ZF rats became hypertensive compared to the control WKY rats. Serum levels of angiotensin-II, the active product of the renin-angiotensin system, were elevated in both SHRSP and SHRSP-ZF rats, but only the SHRSP-ZF rats developed insulin resistance, dyslipidemia, and hyperleptinemia and exhibited an increase in adipose tissue. The development of AOM-induced colonic preneoplastic lesions and aberrant crypts foci, was significantly accelerated in both SHRSP and SHRSP-ZF hypertensive rats, compared to WKY normotensive rats. Furthermore, induction of oxidative stress and exacerbation of inflammation were observed in the colonic mucosa and systemically in SHRSP and SHRSP-ZF rats. Our findings suggest that hypertension plays a role in the early stage of colorectal carcinogenesis by inducing oxidative stress and chronic inflammation, which might be associated with activation of the renin-angiotensin system.     

Investigation and consideration on landslide zoning of multiple slope failures and debris flows of 2014 disaster in Hiroshima,Japan

This study was intended to examine the mechanism of multiple slope failures and debris flows that occurred in the outskirts of Hiroshima on 20th August 2014. A field survey of the mountain stream where large-scale damage was incurred was carried out and the characteristics of debris flows which made serious damages were investigated. There were five findings of this study. (1) The initiation of debris flows was not limited to thin and planar shallow failures, but also showed V or U shapes, where the eroded sediments seemed to be pushed out by artesian water, and the eroded depth exceeded several meters at many locations. (2) There were areas with high permeability, such as faults, fracture zones, and joints in Mt. Abusan. It is inferred that the constantly present groundwater in these areas became artesian water because of a large amount of rainfall in upstream locations. This quickly destabilized the slopes on a large scale. (3) There were at least three estimated debris flows at the mountain stream above Midorigaoka prefectural apartments in Yagi 3-Chome, where the worst damage occurred. The mountain stream near Abu-no-Sato housing complex also had multiple debris flows. Here, the secondary debris flow changed its flow path because of the presence of sediments from an earlier debris flow. (4) The actual volumes of flowed mass were much larger than that predicted at 11 of the 18 mountain streams in Midori-i and Yagi districts. The volume of the mass of five of these mountain streams was more than twice the estimated volume. It is necessary to modify the method of calculating the volume of unstable sediments in the mountain stream. (5) It was found that the devastating damage of buildings and human lives took place in the areas well beyond the special restricted zones. The present method to designate the special restricted zone must be revised considering such problems as the underestimation of the volume of unstable sediments, the assumptions of a single debris flow and on the direction of debris flow, and the effect of the difference on rock and soil types.     

Fabrication of 64×64 arrayed-waveguide grating multiplexer onsilicon

A 64 channel arrayed-waveguide multiplexer with 0.4 nm (50 GHz) channel spacing at 1.55 μm has been fabricated using SiO₂-Si waveguides. The authors obtained a crosstalk of less than -27 dB to neighbouring and all other channels. The on-chip insertion loss ranges from 3.1 to 5.7 dB for central and peripheral output ports, respectively     

Layer-by-layer self-assembled mutilayer films of gold nanoparticles for surface-assisted laser desorption/ionization mass spectrometry

Layer-by-layer (LBL) self-assembled multilayer films of gold nanoparticles (AuNPs) on a silicon wafer were demonstrated to be promising substrates for surface-assisted laser desorption/ionization (SALDI) mass spectrometry (MS) of peptides and environmental pollutants for the first time. LBL multilayer films, (AuNPs/PAHC)n, consisting of alternating layers of ammonium citrate capped AuNPs and poly(allylamine hydrochloride) (PAHC) were prepared on a silicon surface. Silicon plates with aggregated AuNPs were more suitable than those with dispersed AuNPs for the SALDI-MS of peptides. The number of particle layers had a significant effect on the laser desorption/ionization of angiotensin I; the peak intensity of the peptide (molecular ion amount) increased with an increase in the number of layers of AuNPs. As a result, the (AuNPs/PAHC)5 multilayer films increased the sensitivity of the angiotensin I to subfemtomoles and raised the useful analyte mass range, thus making it possible to detect small proteins (a 12 kDa cytochrome c). The signal enhancement when using (AuNPs/PAHC)5 may be due to (i) the high absorption of the UV laser light at 337 nm by the AuNP layers, (ii) the low thermal conductivity due to the AuNPs being covered with a thin monolayer of PAHC, and (iii) the increase in the surface roughness (approximately 100 nm) with the number of AuNP layers. Thus, laser-induced rapid high heating of AuNPs for effective desorption/ionization of peptides is possible. In addition, it was found that (AuNPs/PAHC)5 could be used to extract environmental pollutants (pyrene and dimethyldistearylammonium chloride) from very dilute aqueous solutions with concentrations less than 10(-10) mg/mL, and the analytes trapped in the LBL film could be identified by introducing the film directly into the SALDI mass spectrometer without needing to elute the analytes out of the film.