Improved fracture toughness and fatigue life of carbon fiber reinforced epoxy composite due to incorporation of rubber nanoparticles

In this study, core–shell rubber (CSR) nanoparticles with approximate particle size of 35 nm were used as a modifier for the epoxy polymer. The effects of various CSR contents in the epoxy matrix on mode I interlaminar fracture toughness, tensile strength, and fatigue life of the carbon fabric reinforced epoxy (CF/EP) composites were investigated. The experimental results showed that the mode I interlaminar fracture toughness at crack initiation and propagation significantly improved by 71.21 and 58.47 %, respectively, when 8.0 wt% CSR was dispersed in the epoxy matrix. The fatigue life of the modified CF/EP composites at all of CSR contents dramatically increased 75–100 times longer than that of the unmodified CF/EP composites at high cycle fatigue while tensile strength slightly increased by about 10 %. Field emission scanning electron microcopy (FESEM) observations of the fracture surfaces were conducted to explain failure mechanisms of CSR addition to the CF/EP composites. The evidences of the rubber nanoparticle debonding, plastic void growth, and microshear banding were credited for delaying the onset of matrix crack, and reducing the crack growth rate, as a result, attributed to increase in the mechanical properties of the CF/EP composites.     

Changes in high K+-evoked serotonin release and serotonin 2A/2C receptor binding in the frontal cortex of rats with thioacetamide-induced hepatic encephalopathy

Protein import into the nucleus is generally considered to involve specific nuclear localization signals (NLS) though it is becoming increasingly clear that efficient and well controlled import of proteins which lack a canonical NLS also occurs in cells. Human immunodeficiency virus type 1 (HIV-1) Vpr is one such protein which does not have an identifiable canonical NLS and yet efficiently localizes to the nuclear compartment. Here, we use confocal microscopy to demonstrate that mutations in the putative central hydrophobic helix of Vpr result in the retention of the protein in highly localized ring-like structures around the nuclear periphery with striking impairment in their ability to enter the nuclear interior. By characterizing other biological activities associated with this protein, such as its ability to incorporate into budding virions and its ability to arrest cells in G2, we show that this helical domain is specific for the nuclear translocation of the protein with very little effect on these other functions. Interestingly, however, perturbation of this helical motif also perturbs the protein's ability to augment viral replication in primary human macrophages indicating that the integrity of this secondary structure is essential for optimal infection in these non-dividing cells.     

Effective Dissolution of Platinum by Using Chloride Salts in Recovery Process

Platinum (Pt) is typically recovered by employing dissolution processes in aqueous solutions; however, these processes require a long processing time and considerable quantities of acids with strong oxidants owing to the high chemical stability of Pt. In order to develop an efficient dissolution process, we studied chlorination treatments for Pt prior to dissolution. Chlorination was carried out at 673?K to 873?K (400?°C to 600?°C) using copper(II) chloride (CuCl₂) as a chlorine source. While pure Pt was insoluble in hydrochloric acid (HCl(aq)), the entire Pt component of the treated sample dissolved in HCl(aq) under certain conditions. Therefore, the proposed method can be used as a new, environmental friendly Pt recovery process.     

Quantitative risk assessment of noroviruses in drinking water based on qualitative data in Japan

Noroviruses are one of the major causes of viral gastroenteritis in Japan. A quantitative risk assessment was conducted to evaluate the health risk caused by this virus in drinking water. A Monte Carlo analysis was used to calculate both the probability of infection and the disease burden using disability-adjusted life years (DALYs). The concentration of noroviruses in tap water was estimated based on qualitative data and a most probable number (MPN) method with an assumed Poisson lognormal distribution. This numerical method was evaluated using two sets of available count data of Cryptosporidium: that collected from a river and that found in tap water in Japan. The dose-response relationships for noroviruses were estimated using assumed ID50 (10 or 100). The annual risk was higher than the US-EPA acceptable level (10(-4) [infection/ person-year]) but around the WHO level (10(-6) [DALYs/ person-year]). As suggested by others, since microbial concentrations are generally lognormally distributed, the arithmetic mean was directly related to the annual risk, suggesting that the arithmetic mean is more useful in representing the degree of microbial contamination than the geometric mean.     

Tomakomai Large Scale Crude Oil Fire Experiments

This paper summarizes the results of large-scale crude oil fire experiments conducted in Tomakomai, Japan, in 1998 to obtain information that could be applied to the development of firefighting strategies for, and the design of, huge petroleum storages. Arabian light-equivalent crude oil was burned in pans 5-, 10-, and 20-m in diameter. Most of the experiments were performed under favorable conditions. Measured data include external radiation, infrared image of the flame, flame temperature, gas concentration inside the flame, and other burning characteristics. The height of the strongest radiant emittance was H/D=0.1 to 0.2, where D=pan diameter and H=height from the initial fuel surface, and a kind of fireball appeared occasionally at the intermittant flame zone. Emitted smoke particles were sampled on the ground and observed with a scanning electron micrograph, and the distribution of the diameters of primary smoke particles was examined. The average diameter of primary smoke particles is 53.0 (±10.5)nm. The dependence of burning characteristics and flame structure on pan diameter is discussed. The flame height of the 20-m diameter pan fire is 1.9 (±0.3) D. The burning rate increases as the pan diameters increase, but the radiative fraction decreases as pan diameter increases.     

Synthesis and photoinduced surface relief grating formation of novel photo-responsive amorphous molecular materials, 4-[bis(9,9-dimethylfluoren-2-yl)amino]-4′-cyanoazobenzene and 4-[bis(9,9-dimethylfluoren-2-yl)-amino]-4′-nitroazobenzene

Novel azobenzene-based photo-responsive amorphous molecular materials, 4-[bis(9,9-dimethylfluoren-2-yl)amino]-4′-cyanoazobenzene and 4-[bis(9,9-dimethylfluoren-2-yl)amino]-4′-nitroazobenzene, have been synthesized and the formation of surface relief grating on their amorphous films has been investigated. It was found that a relatively large surface relief grating could be inscribed on both amorphous films upon interference exposure to the writing laser beams. The modulation depth of the surface relief grating inscribed on the amorphous film of the cyano-substituted material was found to be larger than that inscribed on the film of the nitro-substituted one and seemed to be comparable to that inscribed on the amorphous film of the parent material, 4-[bis(9,9-dimethylfluoren-2-yl)amino]azobenzene. These results were discussed from the viewpoint of their trans–cis photoisomerizations as amorphous films and glass-transition temperatures.     

Stereospecific analysis of monounsaturated triacylglycerols in cocoa butter

The enantiomeric composition of the monounsaturated triacylglycerols (TG) from cocoa butter was estimated. The monounsaturated TG were separated into three fractions by reversed-phase high-performance liquid chromatography (HPLC), and each fraction was subjected to the stereospecific analysis with chiral-phase HPLC. The results indicated that the major TG consisted of equal amounts of 1-stearoyl-2-oleoyl-3-palmitoyl-sn-glycerol (SOP-sn-TG) and POS-sn-TG (47 mol%), 1,3-distearoyl-2-oleoyl-glycerol (SOS-TG) (33 mol%), and POP-TG (19 mol%). The contents of SOP-sn-TG and POS-sn-TG are 1.30 times that of the POP-TG content, and the SOS-TG content is 1.30² times that of the POP-TG content. The term “priority factor” is proposed for the ratio of the stearoyl group/palmitoyl group, 1:30 at thesn-1 andsn-3 or 1(3)-position. It shows a distinct specificity for particular fatty acids or their Coenzyme A esters in random esterification at each position of the glycerol moiety in the biosynthesis of cocoa butter TG.     

Measurement of the isotopic abundance of boron-10 by inductively coupled plasma-quadrupole mass spectrometry

This article describes the method for measuring the isotopic abundance of ¹⁰B in nuclear grade boron carbide using inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS). The results of investigation revealed that both the integration time and the dwell time have a major influence on the reproducibility of ICP-QMS measurements. As a result of optimization of the measurement conditions, reproducibility below 0.2% relative standard deviation (RSD) (0.17% RSD maximum) was achieved. In addition, the measured value of the isotopic abundance of ¹⁰B for each sample well agreed with the values measured by the TIMS. Thus, the method described in the present investigation was very effective in the analysis of isotopic abundance of ¹⁰B in B₄C or H₃BO₃. The results of this study suggest that ICP-QMS could be applied to the precise analysis of the isotopic abundance of ¹⁰B required in the field of nuclear applications.     

The effect of small dose of topiroxostat on serum uric acid in patients receiving hemodialysis

Introduction : Topiroxostat, a recently developed xanthine oxidase inhibitor, is expected to have fewer adverse effects than allopurinol because it has different mechanism of action from alloprinol. However, its dosage, usage and safety have not been established in patients with impaired renal function or those undergoing dialysis at the development since no studies was conducted in these patients. Methods : Cross over clinical trial using 3 months of allopurinol and topiroxostat on 27 maintain Japanese HD patients were carried out. The effects on oxidative stress status of both drugs were also evaluated by measuring oxidation reduction potential. Findings : Twenty‐five of twenty‐seven patients completed study. The mean serum uric acid levels in the topiroxostat‐treated arm was significantly lower than it in the allopurinol‐treated arm time‐dependently (P < 0.0001). Corrected oxidative stress ratio defined as biological antioxidant potential/diacron reactive oxygen metabolites was significantly increased in topiroxostat‐arm (*P = 0.0035), but not in allopurinol‐arm (P = 0.1429). No significant difference was seen in diacron reactive oxygen metabolites, biological antioxidant potential, static oxidation‐reduction potential, and capacity oxidation‐reduction potential between pre and post treatment of both drugs. Discussion : It is suggested that a low dose of topiroxostat decreased serum uric acid sufficiently to maintain it below 7.0 mg/dL in patients receiving hemodialysis.