► We examine mechanical properties of Al alloys produced by several casting processes. ► The mechanical properties obtained are different depending on the casting process. ► The mechanical properties ...are related to the lattice mis-orientation angle. ► The tensile strengths are evaluated by Hall–Petch relations. ► The fatigue properties are explained by power law dependence.
The mechanical properties of an Al–Si–Cu alloy (ADC12), produced using various casting technologies, have been examined experimentally. Four different casting processes were employed, including gravity casting (GC), cold-chamber die-casting (CD), twin rolled continuous casting (TRC) and the Ohno continuous casting process (OCC). Although these produced the same Al–Si–Cu aluminum alloy, different mechanical properties were obtained, in particular microstructural characteristics and dislocation density. The microstructure of GC and CD samples was formed mainly with coarse α-Al phase and needle-shaped Si and Fe based eutectic structures. In contrast, a fine round α-Al phase and tiny eutectic structures were observed for the TRC and OCC samples. Such a change of microstructure was caused by the different casting process parameters, namely injection speed, casting pressure and cooling rate. High internal stress as well as high dislocation density was detected for GC and TRC, caused by the high shrinkage force and high applied rolling force, respectively. Because of the different material properties, the tensile and fatigue strength were altered. A clear Hall–Petch relation with σ0.2=kyd−0.5+B was obtained, and the fatigue properties were evaluated with the power law dependence σa=σfNf−b. The mechanical properties obtained were also analyzed in relation to the crystal orientation and lattice mis-orientation angle.
Optical transition edge sensor (TES) detectors that can resolve the energy of a single optical photon have proven to be desirable in multicolor fluorescence microscopy. Here, detectors with a higher ...energy resolution can distinguish dyes having similar or closer emission wavelengths, thus enabling the observation of multiple kinds of dyes simultaneously. To improve energy resolution, it is necessary to know how different the measured energy resolution is from the limit determined by the temperature sensitivity αI and current sensitivity βI, as extracted from the complex impedance. Due to the very fast response of an optical TES (the time constant is shorter than 1 µs), the complex impedance must be measured up to frequencies larger than 10 MHz. However, at high frequencies, the parasitic impedance in the circuit and reflections of electrical signals caused by discontinuities in the characteristic impedance of the readout circuits become significant. To reduce these effects, twisted pair cables are replaced with coaxial ones in this work; thus, a cleaner transfer function of the readout at high frequencies is obtained. The measured impedance of the studied TES is consistent with that given by the single-block model.
We describe the details of a silicon–tungsten prototype electromagnetic calorimeter module and associated readout electronics. Detector performance for this prototype has been measured in test beam ...experiments at the CERN PS and SPS accelerator facilities in 2015/16. The results are compared to those in Monte Carlo Geant4 simulations. This is the first real-world demonstration of the performance of a custom ASIC designed for fast, lower-power, high-granularity applications.
Three platinum–cobalt resistance thermometers (PtCoRTs), which are manufactured in a structure similar to a capsule-type standard platinum resistance thermometer (SPRT), were calibrated against the ...capsule-type SPRTs, which was calibrated based on the International Temperature Scale of 1990 (ITS-90) at NMIJ. The thermometers were calibrated in the temperature range from the triple point of equilibrium hydrogen to the triple point of water by using the dissemination system of the ITS-90 at NMIJ. In this study, the temperature dependence of the resistance ratio,
W
, which is the ratio of the resistance obtained at each temperature by the calibration to the resistance at the triple point of water, is obtained for each PtCoRT. In the temperature region below the triple point of Ne, the temperature dependence of
W
of each PtCoRT is fitted by a 4th-order polynomial. In the temperature region above the triple point of Ne, a 13th-order polynomial is fitted to the temperature dependence of
W
. It was found that residuals for the polynomial fits of each PtCoRT were less than 0.3 mK in both temperature regions.
► Ozokerite, which mainly consists of aliphatic series of hydrocarbons, is used as a food additive for a gum base. ► Ozokerite caused systemic chronic inflammation due to a foreign body response in ...rats. ► Ozokerite caused hepatocellular adenoma in male rats.
Combined chronic toxicity and carcinogenicity studies of ozokerite (OZK), a natural wax substance used as a food additive for a gum base, were performed in male and female F344 rats. Dietary concentrations of 0%, 0.05%, 0.1% and 0.2% OZK were applied in a 52-week chronic toxicity study and 0%, 0.1% and 0.2% in a 104-week carcinogenicity study. In the chronic toxicity study, treatment with OZK caused a xenobiotic reaction against absorbed OZK, including formation of histiocytosis and granulomas with crystalline material in many organs in all of the treated males and females. Particularly in the liver, granulomatous inflammation was accompanied by hepatocellular vacuolation and changes in the serum biochemical parameters indicative of hepatic disorder. The number and area of glutathione S-transferase placental form (GST-P) positive foci were increased in all of the treated groups of both sexes, suggesting the proliferative effect of OZK. In the carcinogenicity study, the incidence of hepatocellular adenoma and the total tumor incidence in the liver of all of the treated males were significantly increased compared with the controls. In conclusion, long-term exposure to OZK caused systemic chronic inflammation due to a foreign body response. OZK was weakly carcinogenic in the liver of male F344 rats.
The combined effects of various carcinogens found in food products are a concern for human health. In the present study, the effects of flumequine (FL) on the in vivo mutagenicity of ...2-amino-3,8-dimethylimidazo4,5-
f
quinoxaline (MeIQx) in the liver were investigated. Additionally, we attempted to clarify the underlying mechanisms through comprehensive gene analysis using a cDNA microarray. Male
gpt
delta mice were fed a diet of 0.03 % MeIQx, 0.4 % FL, or 0.03 % MeIQx + 0.4 % FL for 13 weeks. The effects of cotreatment with phenobarbital (PB) were also examined. Treatment with MeIQx alone increased
gpt
and Spi
−
mutant frequencies, and cotreatment with FL, but not with PB, further exacerbated these effects, despite the lack of in vivo genotoxicity in mice treated with FL alone. FL caused an increase in
Cyp1a2
mRNA levels and a decrease in
Ugt1b1
mRNA levels, suggesting that the enhancing effects of FL may be due in part to modification of MeIQx metabolism by FL. Moreover, FL induced an increase in hepatocyte proliferation accompanied by hepatocellular injury. Increases in the mRNA levels of genes encoding cytokines derived from Kupffer cells, such as
Il1b
and
Tnf
, and cell cycle-related genes, such as
Ccnd1
and
Ccne1
, suggested that FL treatment increases compensatory cell proliferation. Thus, the present study clearly demonstrated the combined effects of 2 different types of carcinogens known as contaminants in foods.
Die cast aluminium alloys, including automotive parts, are generally understood to suffer some degradation of their mechanical properties over time due to corrosion, specifically when exposed to ...water and sea breeze (salt air). However, in this study, it is shown that in the absence of a corrosive environment, the mechanical properties of die cast aluminium alloys actually increase over a 10 year period due to natural aging. The increment in the mechanical properties is mainly attributed to precipitation hardening brought about by θ″ phase particles. It also appears that any significant change in microstructure affects the mechanical properties, e.g. the change of the needle-like eutectic Si to a spherical form and the joining of discrete α-Al phases to make larger grains. The driving force for the microstructural changes upon natural aging is related to the residual stress in the die cast sample accumulated by high casting pressure and rapid cooling rate during injection process.
The intake of salt and salty food is known as a risk factor for gastric cancer. We have previously demonstrated that a high-salt diet dose-dependently enhances Helicobacter pylori (H. ...pylori)-associated gastritis and stomach carcinogenesis in Mongolian gerbils. In this study, we focused on the influence of excessive salt intake on the expression of inflammatory mediators involved in progression of H. pylori-induced chronic gastritis.
A total of 45 stomach samples from Mongolian gerbils were evaluated by immunohistochemistry. The animals were infected with H. pylori and fed basal (0.32%) or a high-salt (10%) diet, and sacrificed after 40 weeks. Proliferative activity and expression of cyclooxygenase-2 (COX-2) in gastric mucosa were significantly increased in H. pylori-infected gerbils. The additional high-salt diet significantly up-regulated the expression of inducible nitric oxide synthase (iNOS) and COX-2 in H. pylori-infected groups (P<0.01 and P<0.05, respectively), while no significant effects were noted in non-infected animals. There was significant synergistic interaction between H. pylori infection and 10% NaCl diet on the expression of iNOS (P<0.05) and also a tendency for enhanced COX-2 expression (P=0.0599).
The present results suggest that a high-salt diet works synergistically with H. pylori infection to enhance iNOS and COX-2 expression in the gastric mucosa of Mongolian gerbils, and support the hypothesis that excessive salt intake may be associated with progression of H. pylori-induced gastritis.
In this paper, the fatigue strengths of cast aluminium alloys have been examined using the S-N and da/dN-ΔK approaches on various cast samples having different microstructural characteristics. These ...were made by several different casting techniques, namely gravity casting, die casting and twin rolled continuous casting. Owing to the different microstructures, the fatigue properties varied. The S-N relations, e.g. the endurance limit, of the twin-rolled casting were apparently high compared to the other cast samples. The high fatigue strength was related to the high tensile strength and high ductility caused by the tiny spherical α-Al phase and fine eutectic structure. On the other hand, the low fatigue strength for the gravity and die cast samples was caused by the high stress concentration caused by the α-Al phase and needle-like eutectic silicon. Unlike the fatigue strength in the S-N approach, the da/dN-ΔK relationships for the twin rolled casting sample, i.e. the resistance to fatigue crack propagation, were low compared to the gravity casting and the die cast samples. Such a difference in the crack growth resistance was influenced by the crack growth characteristics. For example, for the gravity cast and the die cast samples, the crack growth occurs in the grain boundaries of the coarse α-Al phase and along the long eutectic silicon grains (zigzag crack path), which promotes a strong crack closure tendency, leading to high crack growth resistance. The difference in the fatigue strength determined from the S-N relation and da/dN-ΔK relation was interpreted by experimental and numerical examination of the stress-strain distribution.
The constant-volume gas thermometer (CVGT) of the National Metrology Institute of Japan (NMIJ), AIST with
3
He as the working gas is used as an interpolating gas thermometer to realize the ...International Temperature Scale of 1990 (ITS-90) from 3 K to 24.5561 K and as a relative gas thermometer for thermodynamic temperature measurement calibrated at the triple point (TP) of Ne. The standard uncertainties of the realization and measurement are estimated to be 0.58 mK and 0.86 mK at a maximum in the mentioned temperature range, respectively. The maximum difference between both temperatures is about 1 mK. In the calibration of the CVGT, the TP of equilibrium hydrogen (e-H
2
) is corrected for isotopic composition as specified in the Technical Annex for the ITS-90. The ambiguity of the TP of Ne due to the variability in isotopic composition is included in the uncertainty. Although the CVGT was also used in 2004 to realize the ITS-90, it was modified for the present experiment to reduce some measurement uncertainty components and the working gas was replaced with a higher-isotopic-purity gas. The results from 2004 were recalculated by correcting for the isotopic composition of e-H
2
and differ insignificantly from the present results, except for a wider scatter.
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