Trigger electronics of the new Fluorescence Detectors of the Telescope Array Experiment

The Telescope Array Project is an experiment designed to observe Ultra High Energy Cosmic Rays via a “hybrid” detection technique utilizing both fluorescence light detectors (FDs) and scintillator surface particle detectors (SDs). We have installed three FD stations and 507 SDs in the Utah desert, and initiated observations from March 2008. The northern FD station reuses 14 telescopes from the High Resolution Fly's Eye, HiRes-I station. Each of the two southern FD stations contains 12 new telescopes utilizing new FADC electronics. Each telescope is instrumented with a camera composed of 256 PMTs. Since the detectors are composed of many PMTs and each PMT detects fluorescence photons together with the vast amount of night sky background, a sophisticated triggering system is required. In this paper, we describe the trigger electronics of these new FD stations. We also discuss performance of the FDs with this triggering system, in terms of efficiencies and apertures for various detector configurations.     

Assessment of concentrations of toxic elements in aquaculture food products in Malaysia

Thirteen species of aquaculture food products, including fresh water and marine fish, prawns, and seaweed were collected from 37 aquaculture farms in Malaysia. Muscle and liver specimens from these species were tested for the presence of As, Cd, Cr, Cu, Hg, Pb, and Zn by using a heat vaporisation atomic absorption spectrophotometer and an inductively coupled plasma atomic emission spectrophotometer. Sea bass from each collected site were comparatively studied, where As concentrations were assumed to be caused by different culture system; and, Hg and Pb concentration were assumed to be due to anthropogenic activities in specific sites. The calculated estimated intake values of Malaysians for total As, Cd, Cr, Cu, Hg, Pb, and Zn in the muscle of the examined species were 3.713, 0.115, 0.113, 4.268, 0.211, 0.738 and 15.863 μg/kg b.w./day. None of the values exceeded the JECFA guideline values and would pose no health hazards for consumers.     

New approaches to fabrication of multilayer Fresnel zone plate for high-energy synchrotron radiation X-rays

A multilayer (sputtered-sliced) Fresnel zone plate (FZP) is one of the promising focusing optics with high spatial resolution for the high-energy X-ray region. This is because a large “aspect ratio” can be realized easily. In addition, it is important that the kinoform FZP (theoretical diffraction efficiency=100%) can be fabricated by the sputtered-sliced method. This paper presents the experimental results of two new approaches for fabrication of a multilayer FZP for X-rays. (1) To achieve higher diffraction efficiency, a multilevel-type (4-step: quasi-kinoform type) FZP was fabricated. This FZP was composed of concentric multilayers of alternating high-Z, low-Z, and composite materials. The composite material layer was deposited by co-sputtering of high-Z and low-Z materials. (2) To achieve smoother zones (multilayer interfaces) at the conventional-type FZP, each target of a sputtering apparatus with two DC-sputtering guns was surrounded by a cover with an aperture, and Ar gas was supplied inside the cover, which led to the deposition at lower Ar gas pressure. As a result, for the former, the efficiency was improved markedly as compared with conventional FZP, and for the latter, the zone roughness was reduced, which has resulted in the improvement of the spatial resolution of the FZP.     

Study on detection of drugs in slimming health foods using GC-MS/MS

The determination of five drugs, fenfluramine (FEN), N-nitrosofenfluramine (NFE), sibutramine (SIB), mazindol (MAZ) and phenolphthalein (PHP), was studied in slimming health foods using GC-MS/MS. These drugs have been detected at high rates, especially in slimming health foods. Prolonged or excessive consumption of non-approved or unauthorized pharmaceuticals may cause serious adverse health consequences. In this study, samples were extracted with methanol and ultrasonication. Analyses were performed by GC-MS/MS, using established MS/MS parameters in the electron ionization (EI) mode and chemical ionization (CI) mode. In the EI mode, the recoveries of five drugs from several types of slimming health foods such as tablets, capsules and tea-bags spiked at 1 μg/mg (except PHP, spiked at 4 μg/mg) were in the range of 85.0-110.7% and 100 μg/mg (except PHP, spiked at 200 μg/mg) were 94.9-102.9%, respectively. In the CI mode, good recoveries of 80.3-102.2% (spiked at low concentration) and 92.8-103.2% (spiked at high concentration) were also obtained. We evaluated the present method using four slimming health foods, in which drugs had previously been detected. The results were similar to the previous results. These findings indicate that the present procedure for evaluating five drugs in slimming health foods by means of GC-MS/MS is useful.     

Antiplatelet adhesion behavior of hyperbranched poly(l-lactide)s containing glutamic acid terminal groups

The surface properties and antiplatelet adhesion behavior of terminally functionalized hyperbranched poly(l -lactide)s (HB PLLAn-Glu, n = 5, 10, 20) were examined. Contact angle changes and X-ray photoelectron spectroscopic measurements indicated that the hydrated glutamic acid units in HB PLLAn-Glu films migrated to the surface during immersing in water and unique microdomains were observed from the HB PLLA10-Glu film after water immersion. HB PLLA10-Glu and HB PLLA5-Glu prevented platelet adhesion, but HB PLLA20-Glu showed the typical platelet adhesion response for a hydrophobic surface. Both the high hydrophilicity and microdomain formation of HB PLLAn-Glu contributed to the efficient antiplatelet adhesion behavior. The glutamic acid-terminated HB PLLA10-Glu films were more effective at preventing platelet adhesion than the 2-methoxyethoxy-terminated HB PLLA10 films. This study is the first example of platelet adhesion properties being controlled by the terminal functional groups and branching density of hyperbranched polymers. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46910.     

Cementite dispersed in carbons from ferrocene,vinylferrocene, divinylbenzene systems

Cementite-dispersed carbon was synthesized by pressure pyrolysis of divinylbenzene-vinylferrocene and divinylbenzene-ferrocene below 600° C. The magnetization of divinylbenzeneferrocene polymer was higher than that of divinylbenzene-vinylferrocene copolymer at temperatures from 300 to 400° C. The saturation magnetization of cementite-dispersed carbon formed above 500° C was dependent only on the iron concentration in the carbon matrix. The coercive force of cementite-dispersed carbon synthesized from divinylbenzene -vinylferrocene copolymer was about 900 Oe as a maximum value, whereas divinylbenzene-ferrocene polymer gave cementite-dispersed carbon with lower coercive force of 200 Oe. The size of cementite particles dispersed in the carbon from divinylbenzene-vinylferrocene copolymer was less than 50 nm diameter, while divinylbenzene-ferrocene (DVB-Fc) polymer gave a carbon containing larger particles up to 130 nm. The feasible initial aggregation of paramagnetic species in DVB-Fc polymer gave large particles of cementite with multiple magnetic domain. Fixation of ferrocene by the carbon-carbon bond to the parent polymer matrix was found to be effective for fine dispersion of cementite particles in the resultant carbon.     

Hydrodesulphurization of thiophene by coal mineral matter and a cobalt-molybdate catalyst in a pulse reactor

A pulse reactor was used to compare the catalytic activity of a commercial desulphurization catalyst (Nalco 471) and of mineral matter from Western Kentucky coal. Hydrodesulphurization of thiophene, a model coal sulphur compound, was the reaction studied. Mineral matter was obtained from the coal in its least altered state by a low-temperature, oxygen-plasma technique commonly referred to as low-temperature ashing. Conversion is determined from the C₄ gases which are separated in a two-column Chromatographic system. At 748 K it was found that thiophene conversion with mineral matter was 12% of that with the commercial catalyst. Relative activities of hydrogenation of intermediate butenes to butane, the effect of presulphiding, and that of pyridine poisoning were also determined.     

Synthesis of iron-dispersed carbons by pressure pyrolysis of divinylbenzene-vinylferrocene copolymer

Versatile carbons with finely dispersed iron were synthesized by pressure pyrolysis of a copolymer prepared from divinylbenzene and vinylferrocene at temperatures below 680? C and pressures of 125 MPa. The pyrolysis conditions of the copolymer were found to influence the final morphology of carbons to give fibrils, spheres and polyhedra. The resulting carbons contained uniformly fine particles of cementite (Fe₃C) which were less than 30 nm in size, whereas the magnetite was dispersed in the carbon matrix by pressure pyrolysis in the presence of water. Highly dispersed cementite in carbon was found to decompose into metallic iron by further heat treatment above 850? C. Porous spherulitic carbons were also synthesized by heat treatment of magnetite containing carbon spherulites.     

Synthesis and properties of magnetite-dispersed carbon by pressure pyrolysis of divinylbenzene-vinylferrocene with water

Magnetite-dispersed carbon was synthesized by pressure pyrolysis of the divinylbenzene-vinylferrocene system in the presence of water at 125 MPa below 700°C. Supercritical water influenced the phase separation of oligomers formed during the pyrolysis to give carbons with various morphologies, such as spherulitic, coalescing spherulitic and polyhedral carbon, depending upon the concentration of water. Carbon spherulites from 5 to 10 μm diameter dispersed with magnetite particles (<100 nm) were synthesized by pyrolysis of divinylbenzene-5.1 mol% vinylferrocene and 20.0 wt% water at 550°C and 125 MPa. The specific area of magnetite-dispersed carbon synthesized at 600°C and 125 MPa was 92 m²g⁻¹ after heat treatment at 800°C for 1 h. The specific area of the carbon specimen increased with decreasing pyrolysis temperature of the parent copolymers from 700 to 550°C. The Curie temperature of magnetite-dispersed carbon was 585°C. Magnetite dispersed in the carbon matrix was reduced to wüstite during the further heat treatment in vacuum. The saturation magnetization of magnetite-dispersed carbon was 79% of the theoretical value, and changed in proportion to the concentration of iron in the carbon matrix.     

Effect of Partially Substituting Ca with Mischmetal on the Microstructure and Mechanical Properties of Extruded Mg-Al-Ca-Mn-Based Alloys

Mg-2Al-1.2Ca-0.2Mn(at%)-based alloys with Ce-rich mischmetal(MM) substitution of 0–0.6 at% for Ca were hot extruded at 400 °C. The effect of MM substitution on the microstructure and mechanical properties of the extruded alloys was investigated. The as-cast Mg-2Al-1.2Ca-0.2Mn alloy is mainly composed of a-Mg, Mg_2Ca and(Mg,Al)_2Ca phases and Al_8Mn_5 precipitates, whereas the substitution of MM brings about the formation of Al_(11)MM_3, Al_2MM phases and Al_(10)MM_2Mn_7 particles with the absence of (Mg,Al)_2Ca phase. The volume fraction of MM-containing phases increases with increasing MM contents. All of the extruded alloys exhibit bimodal microstructure comprising fine dynamically recrystallized grains with almost random orientation and coarse deformed grains with strong basal texture. Dense nanosized planar Al_2Ca and spherical Al–Mn phases precipitate inside the deformed grains. High tensile yield strengths of~ 350 MPa and moderate elongations to failure of 12% are obtained in all extruded alloys; the MM substitution induces negligible difference in the tensile properties at ambient temperature, while the highest MM substitution improves the strength at 180 °C due to the better thermal stability of the fragmented MM-containing phases.