Several bioassays have been carried out to analyze the toxicity and biodegradability of several imidazolium ionic liquids (ILs) in aqueous phase. The synthetized compounds consist of an imidazolium ...cation with two alkyl substituents in positions 3 (R
1) and 1 (R
2) and a counter-ion. The alkyl substituent R
1 has been fixed as a methyl group and the effect of the alkyl chain length (C
1–C
8) of the other substituent (R
2) has been tested. Moreover, the influence of diverse counter-ions A
− (Cl
−, PF
6, XSO
4
−) has been analyzed. Acute toxicity and EC
50 values of each compound in the aqueous solution have been determined by using the Microtox
® standard procedure. Biodegradability of IL has been determined by measuring BOD
5 of aqueous samples containing IL and/or
d-glucose and the IL residual content and/or
d-glucose concentration after this assay. The viability of the microorganisms used in the BOD
5 has been related to the ATP in the samples, measured by a bioluminescence assay. All the ILs tested were not biodegradable in the considered conditions. Besides, it was found that the shorter the chain length of side chain R
2, the lower the toxic effect is. On the contrary, the anion has a little effect on the IL toxicity.
This study aimed to examine whether an elevated activity of heme oxygenase (HO)-1 in the tissue attenuates endothelial cell-leukocyte interactions microvessels in vivo. When rats were pretreated with ...an intraperitoneal injection of hemin, an HO-1 inducer, mesenteric tissues, including their microvessels, displayed a marked induction of HO-1 concurrent with an increase in plasma concentrations of bilirubin-IXalpha, the product of HO-catalyzed degradation of protoheme IX. In these rats, oxidative stress such as superfusion with H(2)O(2) and ischemia-reperfusion of the tissues neither induced rolling nor exhibited adherent responses of leukocytes in venules. In contrast, the oxidative stresses evoked marked rolling and adhesion of leukocytes in the control rats without HO-1 induction. The HO-1 induction also downregulated leukocyte adhesion elicited by other pro-oxidant stimuli such as N(omega)-nitro-L-arginine methyl ester. The decreases in the oxidant-elicited leukocyte adhesive responses under HO-1-inducing conditions were restored by perfusion with zinc protoporphyrin-IX, an HO inhibitor, but not with copper protoporphyrin-IX, which did not inhibit the enzyme. Furthermore, the effects of zinc protoporphyrin-IX were repressed by superfusion with bilirubin or biliverdin at the micromolar level, but not by the same concentration of carbon monoxide, another product of HO. These results indicate that induction of the HO-1 activity serves as a potential stratagem to prevent oxidant-induced microvascular leukocyte adhesion through the action of bilirubin, a product of HO reaction.
Construction on vacuum-compatible straw tracker for COMET Phase-I Nishiguchi, H.; Evtoukhovitch, P.; Fujii, Y. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
958
Journal Article
Recenzirano
The COMET experiment at J-PARC aims to search for a lepton-flavour violating process of muon to electron conversion in a muonic atom, μ-e conversion, with a branching-ratio sensitivity of better than ...10−16, 4 orders of magnitude better than the present limit, in order to explore the parameter region predicted by most of well-motivated theoretical models beyond the Standard Model. The need for such an excellent sensitivity places several stringent requirements on the detector; (i) good momentum resolution, <2%, for 100 MeV/c electron, which is primarily limited by multiple scattering effect for this momentum region, and (ii) high rate capability, up to 5×109μ−/s muon beam by J-PARC. In order fulfil such requirements, we decided to develop the straw-base planar tracker which is operational in vacuum and made of an extremely light material. The COMET straw tracker consists of 10 mm diameter straw tube, longer than 1 m length, with 20μm-thick Mylar foil and 70 nm-thick aluminium cathode.
Recently, two big milestones, detector-performance verification by the full-scale prototype with 100 MeV/c electron beam, and start the assembly of final straw tracker for COMET Phase-I, were achieved. In this article, details of these two big milestones are provided. In addition, some prospects on the straw tracker development towards the COMET Phase-II are also given.
High precision measurements of the ground state hyperfine structure (HFS) of muonium is a stringent tool for testing bound-state quantum electrodynamics (QED) theory, determining fundamental ...constants of the muon magnetic moment and mass, and searches for new physics. Muonium is the most suitable system to test QED because both theoretical and experimental values can be precisely determined. Previous measurements were performed decades ago at LAMPF with uncertainties mostly dominated by statistical errors. At the J-PARC Muon Science Facility (MUSE), the MuSEUM collaboration is planning complementary measurements of muonium HFS both at zero and high magnetic field. The new high-intensity muon beam that will soon be available at H-Line will provide an opportunity to improve the precision of these measurements by one order of magnitude. An overview of the different aspects of these new muonium HFS measurements, the current status of the preparation for high-field measurements, and the latest results at zero field are presented.
We conducted a high-power test of a prototype cavity of a 324-MHz interdigital H-mode drift tube linac (IH-DTL) for the precise measurement of the muon anomalous magnetic moment (g−2) and electric ...dipole moment (EDM). This prototype cavity (short IH) was developed to verify the fabrication methodology for the IH-DTL cavity with a monolithic drift tube structure. The electromagnetic field distribution was measured and compared with the finite element method simulation results, and the fabrication accuracy of the monolithic drift tube was confirmed to satisfy the requirements. After 40 h of conditioning, the short IH was stably operated with an rf power of 88 kW, which corresponds to a 10% higher accelerating field than the design field (E0) of3.0MV/m. In addition, the thermal characteristics and frequency response were measured, verifying that the experimental data were consistent with the three-dimensional model. In this paper, the design, fabrication, and low-power and high-power tests of this IH-DTL for muon acceleration are described.
Density, ρ; refractive index on mixing, n D; and speed of sound, u; at 293.15 K, 298.15 K, 303.15 K, and 313.15 K and atmospheric pressure have been measured for binary mixtures of diethyl carbonate ...(DEC) + methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, or 1-pentanol. Excess molar volumes, V E; changes of refractive index on mixing, Δn D; and deviations in isentropic compressibility, Δκ S; for the above systems have been calculated. The Redlich−Kister equation has been used to estimate the binary fitting parameters, and root-mean-square deviations from the regression lines are shown. The V E values were fitted as a function of the mole fraction and temperature to a polynomial equation.
Radiation-tolerant n+-in-p silicon sensors were developed for use in very high radiation environments. Novel n+-in-p silicon strip and pixel sensors and test structures were fabricated, tested and ...evaluated, in order to understand the designs implemented. The resistance between the n+ implants (interstrip resistance), the electric potential of the p-stop, and the punch-through-protection (PTP) onset voltage were measured before and as a function of fluence after irradiation. The technology computer-aided design (TCAD) simulations were used to understand the radiation damage and fluence dependence of the structures. The decrease in the interstrip resistance is a consequence of increased leakage current. The decrease in the electric potential of the p-stop results from a build-up of positive charge in the silicon–silicon oxide interface. The decrease and subsequent increase in the PTP onset voltages results from the interface charge build-up and an increase in acceptor states.
J Oral Pathol Med (2012) 41: 1–8
Oral cancer is one of the most frequent head and neck cancers, and epidemiological studies have shown that smoking is a major risk factor in this pathology. However, ...as not all smokers develop oral cancer, some individuals must be more susceptible to develop this disease. This individual susceptibility has been related to different genetic variants in metabolizing enzymes. The cytochrome P‐450 (CYP) family of enzymes metabolizes tobacco‐related carcinogens producing reactive metabolites, which could cause DNA damage. Because of their functional role in the metabolism of tobacco‐related compounds, the genetic polymorphisms found in the genes that code for CYP enzymes have been suggested to modulate oral cancer risk and contribute to individual susceptibility. In this review, we analyze and update the available evidence in the literature regarding the polymorphisms of CYP genes in relation to the susceptibility of developing oral cancer.
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