High-field Magnetization of SrMn3P4O14 Having Magnetization Plateau and Ferrimagnetic Long-range Order

It has not been studied sufficiently whether quantum-mechanical character can exist in classical magnetic long-range order of systems with large spins. Very recently, it has been shown that a quantum-mechanical 1/3 magnetization plateau and classical ferrimagnetic long-range order coexist in SrMn₃P₄O₁₄ possessing spin-5/2 [T. Yang et al. in Inorg. Chem. 47:2562, 2008]. Magnetism of this substance has not been explained quantitatively, although the origin of the plateau is inferred to be a trimerized spin chain. We performed high-field magnetization measurements on SrMn₃P₄O₁₄ powders. We consider a spin system in this substance.     

Microscopic characterization of hydrogen-induced quasi-brittle fatigue fracture in low-strength carbon steel

The microscopic feature of hydrogen-induced quasi-brittle fatigue fracture in low-strength carbon steel was investigated by transmission electron microscopy and electron backscatter diffraction. These analyses, aided also by fractography, explicitly revealed the following points; i) brittle striation is formed by extensive slip at the crack tip, ii) quasi-brittle facet is not crystallographically related to the {100} cleavage plane, and iii) crack growth process is stable. These results may suggest that the crack growth, despite its brittle appearance, is essentially a combined process of extensive slip and significantly localized ductile cracking, which is distinct from the normal slip-off growth mechanism.     

A direct determination method for ethanol concentrations in alcoholic beverages employing a eukaryote double-mediator system

A fast, direct, small-sample measurement method of ethanol determination in alcoholic drinks was established by the application of attractive characteristics of a eukaryote double-mediator (EDM) system, as previously reported. The EDM system, which consists of yeast as well as both hydrophilic and hydrophobic mediators, demonstrates superior sensitivity to organic substances. For high performance, the EDM system was reoptimised for ethanol determination with a small sample volume of only 3 μL and a short incubation time of 5 min. Under optimal conditions, a practical calibration curve for ethanol determination in alcoholic beverages was obtained between 0.5 and 50 v/v% (r = 0.997, 9 points, n = 3, average of relative standard deviation, RSD_av = 2.75%), with a detection limit of 0.5 v/v%. To characterise our ethanol determination method, the effects of pH, organic substances, carbon dioxide gas, or sodium sulphite on EDM responses were studied in detail. No notable effects of pH on EDM responses were observed; however, glucose and ascorbic acid strongly increased the EDM response to ethanol. Real sample applications were mainly performed using distilled alcoholic drinks (shochu, brandy, vodka, gin, and whisky) and several kinds of beer and similar beverages (lager, draft, low-malt, non-malt, and sugar-free). When the results with sugar-free beverages were compared with those obtained by the available enzymatic-spectrophotometric (ES) method, an excellent correlation was obtained (r = 0.990, 7 points, n = 3, RSD_av of the EDM method = 7.90%), with an excellent slope of 1.05. Finally, a yeast suspension stored at 4 °C was stable for at least 7 days, with a response reduction of 88% (RSD_av for five testing days = 4.8%).     

Cyclic deterioration and its improvement for Li-rich layered cathode material Li[Ni0.17Li0.2Co0.07Mn0.56]O2

Transmission electron microscopy (TEM) studies were carried out to elucidate cyclic deterioration phenomena for Li-rich layered cathode material Li[Ni_0.17Li_0.2Co_0.07Mn_0.56]O₂. The results obtained show that the deterioration starts during the initial charge/discharge to higher potential over 4.5 V, and leads to the formation of micro-cracks at the crystal surface and the distortion of crystal periodicity. These two kinds of defects lead to further non-crystallization of the crystal surface and the emergence of a very small amount of another possible phase. Our stepwise pre-cycling treatment effectively depressed the formation of the former two kinds of defects, and could significantly improve cyclic durability. The observation of non-crystallization at the cathode crystal surface, which would diminish the battery performance, is consistent with our preliminary ac impedance results.     

Droplet combustion in presence of airstream oscillation: Mechanisms of enhancement and hysteresis of burning rate in microgravity at elevated pressure

The enhancement and hysteresis behavior of the burning rate of single droplet combustion in the presence of airstream oscillation observed in previously performed microgravity experiments at elevated pressure up to 1.0 MPa were numerically investigated. Excellent agreement with the experimental results was obtained and the mechanisms of these phenomena were examined based on precise numerical data on instantaneous droplet diameter variations corresponding to the unsteady airstream velocity, flow fields around the droplet, and flame movement during combustion. Results show that, depending on the oscillation Reynolds number, which is a function of pressure, flow amplitude and droplet diameter, there are three mechanisms involved in the enhancement of burning rate. In the cases of low oscillation Reynolds numbers, a diffusion-time-delay has a significant effect on the flame front movement and thus, on heat from the flame to the droplet. In the cases of high oscillation Reynolds numbers, a vortex generated outside the droplet flame promotes the motion of the flame, especially in the wake region, and thus enhancing the droplet burning rate. In addition to these two mechanisms, the forced convection during the acceleration period of the flow oscillation causes overshooting of the droplet burning rate due to instantaneous imbalances of the airflow momentum with the Stefan flow. These three mechanisms explain the predominant role of the highest velocity of the oscillatory airstream in determination of the mean burning rate constant and droplet lifetime. Results also show that the hysteresis behavior of the burning rate is a consequence of the different responses of the flame to the deceleration period compared with the responses to the acceleration period under the existence of those three mechanisms.     

Highly sensitive and rapid profiling method for carotenoids and their epoxidized products using supercritical fluid chromatography coupled with electrospray ionization-triple quadrupole mass spectrometry

Epoxy carotenoids, which are products of carotenoid oxidation, are potential oxidative stress markers. However, it is difficult to profile epoxy carotenoids owing to their small amount and difficulty in their separation from hydroxy carotenoids. In this study, a high-performance analytical system based on supercritical fluid chromatography (SFC) coupled with tandem mass spectrometry (MS/MS) was developed for the simultaneous analysis of carotenoids and epoxy carotenoids. SFC is an effective separation technique for hydrophobic compounds, by which major carotenoids in human serum and their epoxidation products can be analyzed within 20 min. The use of MS/MS increased the sensitivity; the detection limit for each carotenoid was of the sub-fmol order. When the constructed method was applied to biological samples such as human serum and low-density lipoprotein (LDL), the precise detection of the target carotenoids was disturbed by several isomers. However, highly selective detection of epoxy carotenoids was performed by targeting product ions that were generated with a structure-specific neutral loss of 80Da. Furthermore, the sample volume needed for the analysis was only 0.1ml for the serum, indicating the efficiency of this system in performing small-scale analyses. Using the analytical system developed in this study, highly sensitive and selective analysis of epoxy carotenoids could be performed in a short time. These features show the usefulness of this system in application to screening analysis of carotenoid profiles that are easily modified by oxidative stress.     

Chronic dietary intake of quercetin alleviates hepatic fat accumulation associated with consumption of a Western-style diet in C57/BL6J mice

Scope: To determine the effect of consumption of a quercetin‐rich diet on obesity and dysregulated hepatic gene expression. Methods and results: C56BL/6J mice were fed for 20 wk on AIN93G (control) or a Western diet high in fat, cholesterol and sucrose, both with or without 0.05% quercetin. Triglyceride levels in plasma, thiobarbituric acid‐reactive substances (oxidative stress marker) and glutathione levels and peroxisome proliferator‐activated receptor α expression in livers of mice fed with the Western diet were all improved after 8 wk feeding with quercetin. After 20 wk, further reductions of visceral and liver fat accumulation and improved hyperglycemia, hyperinsulinemia, dyslipidemia and plasma adiponectin and TNFα levels in these mice fed with quercetin were observed. The expression of hepatic genes related to steatosis, such as peroxisome proliferator‐activated receptor γ and sterol regulatory element‐binding protein‐1c was also normalized by quercetin. In mice fed with the control diet, quercetin did not affect body weight but reduces the plasma TNFα and hepatic thiobarbituric acid‐reactive substance levels. Conclusion: In mice fed with a Western diet, chronic dietary intake of quercetin reduces liver fat accumulation and improves systemic parameters related to metabolic syndrome, probably mainly through decreasing oxidative stress and reducing PPARα expression, and the subsequent reduced expression in the liver of genes related to steatosis.