Efficiently activated carbon fiber derived from grafted novoloid fiber

Graft copolymerization of methyl methacrylate onto novoloid fiber was carried out by the electron beam mutual irradiation method. The characteristics of the grafted fiber were almost the same as those of the original novoloid fiber. The grafted fiber was carbonized and activated to yield an efficiently activated carbon fiber. The yield and the specific surface area of the activated carbon fiber, derived from the grafted novoloid fiber, were much greater than those derived from the original novoloid fiber. This is because grafted poly(methyl methacrylate) decomposes into monomer and gaseous products, forming pores on the surface and inside of the novoloid fiber on heating. © 1993 John Wiley & Sons, Inc.     

Development of automatic fault point locating and sectional isolating system for power distribution line

This paper describes the development of the Automatic Fault Point Locating and Sectional Isolating System. This system locates a single-line-to-ground fault point at each pole by using ground-current sensors, and isolates the faulted section by controlling pole switches with no outage of unfaulted sections. The ground-current sensor is connected to the line between allied ground terminals of pole devices and grounded conductor. It detects a ground fault current of more than 0.64 amperes that is determined so as to avoid an unexpected operation by stray current, but to detect the fault current accurately, and sends out an emergency signal with time delay of 0.1 s. Sectional isolation starts when both the emergency signal from the sensor and relay operation signals from a substation are received and ends within a feeder circuit-breaker tripping time of 1.5 s.     

Ethynylvinylidene

Ethynylvinylidene, an energetically low-lying isomer of diacetylene, has been studied using ab initio molecular electronic structure theory. Geometries of diacetylene, ethynylvinylidene, and the transition state between them have been optimized using the double-ζ plus polarization (DZP) and triple-ζ plus double polarization function (TZ2P) basis sets with the self-consistent field (SCF), configuration interaction with single and double excitations (CISD), coupled cluster with single and double substitutions (CCSD), and CCSD with perturbatively included connected triple substitutions [CCSD(T)] methods. At the TZ2P CCSD(T) level of theory only single point energies have been determined at the TZ2P CCSD geometries. Harmonic vibrational frequencies and infrared (IR) intensities are reported for the three stationary points at the DZP SCF, TZ2P SCF, and DZP CISD levels of theory. For ethynylvinylidene, rotational constants, dipole moments, and dipole moment components along the principal axes are also given. This isomer is found to be an extremely shallow minimum on the C₄H₂ potential energy surface, and the classical barrier to rearrangement (to diacetylene) is vanishingly small at the highest level of theory.     

Establishment of a modified rankine method for the separate determination of free and combined sulphites in foods. III

Summary Considerable improvements were made to the original Rankine method. Replacement of aspiration with an injection system contributed a great deal to the simplification of procedure, being accompanied with an increase in reproducibility. Air (flow rate 1.01/min) was used for injection because the use of inert gas gave little increase in recovery rate.Sodium bisulphite (free sulphite) and three kinds of combined sulphite compound (bisulphite adducts of acetaldehyde, pyruvic acid and D-mannose) were used to find the most suitable conditions for the separate determination of free and combine sulphites.Free sulphite was expelled from the sample by bubbling at 0 °C for 30 min. It was confirmed that no combined sulphite was dissociated under these conditions. The phosphoric acid concentration had an important role in the liberation of sulphite. When 25% phosphoric acid was used, more than 99% of free sulphite was expelled by cold bubbling and more than 99% of combined sulphite was recovered by heating afterwards for 10 min.The scope of the modified Rankine method was also extended to the determination of sulphite in concentrated orange juice.

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Verwendung der modifizierten Rankine-Methode zur getrennten Bestimmung von Sulfiten in Lebensmitteln. III

Zusammenfassung Die Rankine-Methode wurde bedeutend verbessert. Ein Umtausch der Aspiration mit Blasensystem trug beträchtlich zur Vereinfachung des Bestimmungsverfahrens bei, und die Reproduzierbarkeit wurde verbessert. Luft (Fließrate 1,01/min) wurde als Blasengas benutzt, da der Gebrauch von Inertgas für die Wiederfindungsrate unbedeutend ist.Natriumhydrogensulfit (freies Sulfit) und drei Arten gebundener Sulfite (Acetaldehydhydrogensulfit, Pyruvathydrogensulfit undd-Mannosehydrogensulfit) dienten dazu, die geeignetsten Bedingungen für die getrennte Bestimmung der freien und gebundenen Sulfite zu ermitteln.Freies Sulfit wurde bei 0 °C durch 30 min Durchblasen vertrieben. Hierbei ging kein gebundenes Sulîit verloren. Die Phosphorsäurekonzentration war wichtig für die Freisetzung des Sulfites. Wenn man 25%ige Phosphorsäure verwendet, werden > 99% freien Sulfites beim Durchblasen in der Kälte vertrieben, während > 99% gebundenen Sulfites durch nachheriges 10 min langes Erhitzen wiedergewonnen werden.Die modifizierte Rankine-Methode wurde weiterhin für konzentrierte Säfte verwendet.

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Studies on the Analyses of Sulphites in Foods (III)     

Retardation of the precipitation reaction by d.c. stress in an Al-12.5 wt % Zn alloy

The effect of direct electric current stress on the precipitation reaction in an Al-12.5 wt % Zn alloy was investigated by the resistometric method. It was found that the d.c. stress retarded the reaction rate as in the case of an Al-4 wt% Cu alloy. The dependence of the retarding effect on the annealing time and on the quenching temperature was examined on the basis of a model of current-assisted vacancy annihilation. The annealing temperatures after quenching were 30 and 40° C, and the quenching temperatures were varied from 300 to 500° C.     

Polymeric ultraviolet absorber

Polymeric fine powder, prepared by polymerization of glycidylmethacrylate–divinylbenzene, was reacted with 2,4-dihydroxylbenzophenone. The resultant polymer was effective as a polymeric ultraviolet absorber, and no migration was observed in polypropylene.     

Copolymerization of styrene–m-divinylbenzene in the presence of poly(vinyl chloride)

The crosslinking copolymerization of styrene (St)-m-divinylbenzene (m-DVB) in the presence of poly(vinyl chloride) (PVC) was studied. The rate of the copolymerization decreased with the addition of PVC powder, because of the depressing of the diffusion of the monomers to the polymerizing center and the difficulty in the transfer of the polymer radicals in the swelled PVC powder. The exponential value of the benzoyl peroxide concentration and the activation energy of the copolymerization were obtained as 0.67 and 17.4 kcal/mol, respectively. The monomer reactivity ratios of St and m-DVB were determined as r₁ = 0.25 and r₂ = 1.42 (M₁: St, M₂: m-DVB). From the extraction of the resultant polymer composite with THF, both the grafting of the St-m-DVB copolymer onto PVC and the entanglement of PVC with St-m-DVB copolymer seems to occur in the St-m-DVB-PVC system.     

Computer analysis of random and channeled backscattering spectra

Three types of computer codes are described which simulate random and channeled backscattering spectra from: (1) multielemental, multilayered structures, (2) specimens with inhomogneously distributed impurities and (3) single crystals damaged by ion implantation. Both effects of energy fluctuation and isotopic shifts from each constituent element are taken into account in the simulation. The elemental compositions and layer thicknesses of multielemental, multilayered films and the damage distributions induced by ion implantation are determined by fitting the simulated spectrum to the corresponding experimental one. The effect of surface and interface roughness on the spectrum shape is also discussed.