Surface characteristics and electrical breakdown of alumina materials

The electrical breakdown of alumina materials is one of the difficulties in higher electric field applications. This breakdown takes place due to localized excess heating, which is induced by surface defects, multipactor, and surface discharge. These factors were evaluated for several commercial alumina ceramics using a scanning electron microscope and comparing these observations with high-power rf transmission tests. The results indicate that alumina ceramics without F-center defects and lower surface charging are feasible for higher electric field operation.     

Secondary electron emission of TiN-coated alumina ceramics

TiN film is often coated on alumina rf windows to suppress multipactor due to high secondary electron emission (SEE) coefficients. In this paper, SEE coefficients of alumina ceramics and sapphire coated with TiN films of various thicknesses are investigated. The SEE coefficients were measured using a scanning electron microscope with a single-pulse electron beam (100 pA, 1 ms). The SEE coefficients of TiN-coated alumina ceramics were lower than those of uncoated ones and nearly unity for TiN thickness of more than 1 nm, even with incident energy of 1 keV. To emulate multipactor-induced surface heating, the SEE coefficients were also measured at high temperature. The results showed a decrease in the SEE coefficients with temperature for TiN thickness of more than 0.5 nm. TiN coating on an rf window should be as thin as possible, and 0.5-1 nm may be the optimum thickness for suppressing multipactor.     

Dynamic behavior of a solid particle bed in a liquid pool: SIMMER-III code verification

Dynamic behavior of solid particle beds in a liquid pool against pressure transients was investigated to model the mobility of core materials in a postulated disrupted core of a liquid metal fast reactor. A series of experiments was performed with a particle bed of different bed heights, comprising different monotype solid particles, where variable initial pressures of the originally pressurized nitrogen gas were adopted as the pressure sources. Computational simulations of the experiments were performed using SIMMER-III, a fast reactor safety analysis code. Comparisons between simulated and experimental results show that the physical model for multiphase flows used in the SIMMER-III code can reasonably represent the transient behaviors of pool multiphase flows with rich solid phases, as observed in the current experiments. This demonstrates the basic validity of the SIMMER-III code on simulating the dynamic behaviors induced by pressure transients in a low-energy disrupted core of a liquid metal fast reactor with rich solid phases.     

Zn protoporphyrin IX is formed not from heme but from protoporphyrin IX

We examined the effects of exogenous myoglobin, a bivalent chelator, and nitrite on Zn protoporphyrin IX (ZPP) formation by using model systems. ZPP was formed in a model solution without addition of exogenous myoglobin. After incubation, the amount of ZPP in a model solution was increased but that of heme was not decreased compared with the amounts before incubation. Protoporphyrin IX (PPIX) instead of ZPP also accumulated in a model solution with addition of EDTA, but the amount of heme was not reduced. These results suggested that ZPP was not formed by the Fe–Zn substitution in heme but was formed by the insertion of Zn into PPIX, which was formed independently. The fact that the effects of various factors in model systems with/without addition of a bivalent chelator were similar suggested that ZPP formation was strongly affected by PPIX formation. Inhibition of PPIX formation by nitrite might be the reason for the low levels of ZPP in cured meats.     

Spring bloom in a hypereutrophic lake, lake Kasumigaura, Japan—III Phytoplankton abundance in standing stock of organic matter in lake water

The rapid increase of phytoplankton biomass was the major process for the increase of particulate organic matter in Lake Kasumigaura in 1980. During the first phytoplankton pulse in the bloom relative abundance of each component of organic matter in the lake water was: dissolved organic matter 100, phytoplankton 28, bacteria 27, and detrital particle 27. This relative abundance was maintained as a steady-state oscillation throughout the spring bloom similar to that usually observed in moderately eutrophic waters. Thus phytoplankton abundance in the standing stock of organic matter of the hypereutrophic water during the spring bloom does not show any marked difference from that of moderately eutrophic waters.     

Monoacylglycerols Activate Capsaicin Receptor, TRPV1

Transient receptor potential vanilloid subtype 1 (TRPV1) is known as capsaicin (CAP) receptor and activated by CAP. Activation of TRPV1 by CAP increases energy expenditure and thermogenesis in rodents or human. Therefore, TRPV1 may be target for energy expenditure enhancement and thermogenesis. To search for novel TRPV1 agonist, we screened 19 types of foods by using TRPV1-expressing HEK293 cells. TRPV1 was activated by hexane extract of wheat flour, and its functional compounds were 1-monoacylglycerols containing oleic, linoleic, and alpha-linolenic acids. Their potencies (EC50) were about 50 times larger than that of CAP and their efficacies (maximal response) were about half of that of CAP. TRPV1 was activated by 1-monoacylglycerols (MGs) having C18 and C20 unsaturated and C8-C12 saturated fatty acid (FA). Moreover, 2-MGs having C18 and C20 unsaturated FA acted on TRPV1 with the same potency. On the other hand, no activation of TRPV1 was induced by MGs having C16 and C18 saturated FA, di- or triacylglycerols of C18:1 FA. Pain-relating aversive responses were induced when TRPV1-activating 1-monoacylglycerols (50 mM) was administered subcutaneously into rat hind paw. These effects were inhibited by the co-injection of capsazepine (10 mM) which is a TRPV1 competitive antagonist. These results suggested that these 1-monoacylglycerols activate TRPV1 in vitro and in vivo.     

Direct demonstration of the presence of zinc in the acetone-extractable red pigment from Parma ham

We studied the presence of zinc in the red pigment extracted from Parma ham by scanning electron microscopy/energy dispersive X-ray microanalysis. The large peak of about 8.6keV and the small peaks at about 1.1keV and 9.5keV were derived from K(α), L(α1) and K(β) X-ray of zinc, respectively. Thus, the results suggested that zinc existed in the red pigment extracted from Parma ham. In contrast, the K(α) X-ray peak of iron (6.4keV) was not detected and the K(α) X-ray peak of magnesium (1.3keV) was hardly detected. These results revealed that the red pigment contained not iron but zinc. In addition to the results of mass analysis in previous studies, the red pigment was demonstrated to be zinc protoporphyrin IX.     

Effect of a dietary supplement containing glucosamine hydrochloride, chondroitin sulfate and quercetin glycosides on symptomatic knee osteoarthritis: a randomized, double-blind, placebo-controlled study

BACKGROUND: Oral glucosamine and chondroitin sulfate, alone and in combination, have been used worldwide for the treatment of osteoarthritis (OA), but their efficacy is controversial. This clinical study was aimed at investigating the potential of a dietary supplement containing glucosamine and chondroitin sulfate in combination with derivatives of quercetin, a naturally occurring flavonoid, (GCQ supplement) for knee OA care. RESULTS: A randomized, double‐blind, placebo‐controlled study was conducted in 40 Japanese subjects with symptomatic knee OA. Subjects were randomly assigned to GCQ supplement (1200 mg glucosamine hydrochloride, 60 mg chondroitin sulfate and 45 mg quercetin glycosides per day) or placebo and the treatment and follow‐up were continued for 16 weeks. The results of symptomatic efficacy assessment based on Japanese Orthopaedic Association criteria showed that scores for two of the four symptom/function subscales, as well as the aggregate scores, were significantly improved at week 16 or earlier in the GCQ group compared to the placebo group. Moreover, analyses of cartilage metabolism biomarkers showed a trend of improvement in type II collagen synthesis/degradation balance in the GCQ group during follow‐up. CONCLUSION: GCQ supplement was thought to be more effective than placebo in decreasing the intensity of knee OA‐associated clinical symptoms. Copyright © 2011 Society of Chemical Industry