Showing papers by "Tohoku University published in 1987"
TL;DR: In this article, a thermodynamically stable quasicrystalline single phase with an icosahedral structure was found to be formed at an atomic composition of Al65Cu20Fe15 in a fully annealed state as well as in a conventionally solidified state.
Abstract: A thermodynamically stable quasicrystalline single phase with an icosahedral structure was found to be formed at an atomic composition of Al65Cu20Fe15 in a fully annealed state as well as in a conventionally solidified state. The stable quasicrystal consisted of large grains with an average size of 0.2 mm after annealing for 48 h at 1118 K (0.98 Tm).
604 citations
TL;DR: In this article, the coupling coefficients of a variational principle for the propagation constant of the waveguide-wave solution using a superposition of the uncoupled modes as a trial field were derived.
Abstract: The coupled-mode theory of parallel waveguides is derived from a variational principle for the propagation constant of the waveguide-wave solution using a superposition of the uncoupled modes as a trial field. The nonorthogonality of modes as emphasized by Hardy and Streifer is part of this formalism as well. The coupling Coefficients agree with those of Hardy and Streifer derived for TE modes of loss-free guides. For TM modes the coupling coefficients differ slightly for the simpler trial solution and agree exactly for a different trial solution. The simpler trial solution gives results closer to the exact solution. Conventional coupled-mode theory emerges from orthonormalization.
418 citations
TL;DR: In this article, a novel polyether toxin, yessotoxin, was isolated from scallops implicated in diarrhetic shellfish poisoning, and its planar structure was proposed by means of modern NMR techniques.
343 citations
TL;DR: Estrogens, such as estrone, estradiol and estriol, were tested as possible antioxidants of lipid peroxidation induced by Fe3+‐ADP‐adriamycin or Fe3 +‐ ADP‐ascorbate.
332 citations
TL;DR: It was concluded that the concomitant use of a high-voltage electrical impulse and an anticancer drug has the potential to be applicable for cancer treatment.
Abstract: Application of a high-voltage electrical impulse (5 kV/cm, 2 msec) after bleomycin administration resulted in a significant size decrease of subcutaneously inoculated AH-109A hepatocellular carcinoma in Donryu rats. The tumor size decreased to an average of 17% of the initial mass 4 days after the treatment. Neither the high-voltage electrical impulse nor bleomycin administration alone showed an inhibitory effect on the tumor growth. It was concluded that the concomitant use of a high-voltage electrical impulse and an anticancer drug has the potential to be applicable for cancer treatment.
327 citations
TL;DR: In this article, a further-miniaturized specimen punch (SP) test was developed to extract fracture strain and strength information from TEM disc specimens as small as 3 mm diameter and 0.25 mm in thickness.
325 citations
TL;DR: In this article, the infrared and Raman spectra of neutral polythiophene were analyzed on the basis of the data of oligomers (α-bithiophene, α-terthiophen, β-quaterthiopane, and α-sexithiophenes) and deuterated and 2,5-13C-substituted polythyphenes.
317 citations
TL;DR: In this article, chemical vapor deposition (CVD) was applied to polycrystalline plates with a deposition rate of 200 μm/h and the lattice parameters of the CVD-Ti3SiC2 were investigated.
282 citations
TL;DR: The results indicated that arachidonic acid was predominantly liberated from inositol‐containing phospholipids byospholipase C, and by the diglyceride lipase and monoglyceridelipase system rather than from phosphatidylcholine or phosph atidylethanolam‐ine by phospholIPase A2 or plasmalogenase or choline phos‐photransferase during the early period of ischemia.
Abstract: Once brain ischemia was induced in the gerbil cerebral fronto-parietal cortex, serial changes occurred in energy metabolites and various lipids. The amounts of inosi-tol-containing phospholipids began to decrease immediately after energy failure, followed by an increase in the amount of 1,2-diacylglycerol with a subsequent liberation of arachidonic acid and other free fatty acids. The fatty acid compositions of inositol-containing phospholipids, of 1,2-diacylglycerols produced by ischemia, and of free fatty acids liberated during ischemia were quite similar. The amount of stearic acid liberated was much larger than that of arachidonic acid between 30 s and 1 min of ischemia. On the other hand, there was no significant decrease in the amount of the other phospholipids except for phosphatidic acid. Furthermore, there was also no change in the fatty acid composition of phosphatidylcholine or phosphatidylethanol-amine throughout 15 min of ischemia. The amount of cytidine-monophosphate reached a peak (36.7 nmol/g wet wt) at 2 min of ischemia. These results indicated that arachidonic acid was predominantly liberated from inositol-containing phospholipids by phospholipase C, and by the diglyceride lipase and monoglyceride lipase system rather than from phosphatidylcholine or phosphatidylethanolam-ine by phospholipase A2 or plasmalogenase or choline phos-photransferase during the early period of ischemia.
271 citations
TL;DR: Two principal toxins of diarrhetic shellfish poisoning, okadaic acid and dinophysistoxin-1, were esterified with 9-anthryldiazomethane in methanol.
Abstract: Two principal toxins of diarrhetic shellfish poisoning, okadaic acid and dinophysistoxin-1, were esterified with 9-anthryldiazomethane in methanol. After cleaning with a Sep-pak silica cartridge column, the fluorescent esters were analyzed on a Develosil ODS column with MeCN- MeOH-H20 (8:1:1). The fluorescence intensities of both toxin derivatives measured at an excitation of 365 nm and an emission of 412 nm showed good linearity in the range 1 ~ 80ng.
262 citations
TL;DR: In this article, the authors examined the properties of the transition layer on the surface of an ice crystal at temperatures just below its bulk melting point (0°C) using ellipsometry.
TL;DR: An unusual large-amplitude (from less than 10 nT to greater than 40 nT) magnetic oscillation characterized by about-13sec periodicity and southward turnings of the field was observed by AMPTE/CCE on August 28, 1986.
Abstract: An unusual large-amplitude (from less than 10 nT to greater than 40 nT) magnetic oscillation characterized by about-13-sec periodicity and southward turnings of the field was observed by AMPTE/CCE on August 28, 1986. The magnetic field was often stronger southward, with some southward components exceeding 20 nT being noted. The level of the high frequency perturbations was also seen to be enhanced. It is suggested that these observations may be due to the formation of an X-type neutral line and its motion near the spacecraft.
TL;DR: In this article, it was shown that the recording bit length at the highest density was of the order of the Co-Cr columnar diameter, which is the diameter of a single-pole head and double-layer medium.
Abstract: Since perpendicular magnetic recording is free from recording demagnetization, high-density recording up to the intrinsic limit of a recording medium is possible. This prediction was verified experimentally in a flexible disk system using a single-pole head and a Co-Cr/Ni-Fe double-layer medium. We could record and reproduce signals up to 680KFRPI. The recording bit length at the highest density was of the order of the Co-Cr columnar diameter.
TL;DR: In this article, the relationship between fracture energy and compressive strength of a sphere has been theoretically studied from the viewpoint of fracture mechanics using experimental results of crushing of spheres, and the authors obtained a new equation for the change in fracture energy with size.
TL;DR: In this article, the authors investigated the relationship between physical parameters in the cohesive zone during stick-slip shear failure and the normal stress σn within a normal stress range less than 17 MPa.
TL;DR: In this article, the authors examined the evolution of Raman spectra of SiC fibres through structural and compositional transformations caused by heat treatment, and they showed that the carbon microcrystals play an important role in maintaining the high mechanical strength of the SiC fibre.
Abstract: We have examined the evolution of Raman spectra of SiC fibres through structural and compositional transformations caused by heat treatment. The SiC fibre was made from polycarbosilane. Raman spectra of the SiC fibre indicate that it consists of (i) amorphous or microcrystalline SiC, (ii) carbon microcrystals, and (iii) silicon oxide. The amount of microcrystalline carbon in the fibre increases with heat treatment temperature up to 1400° C, and it decreases abruptly in those fibres heat treated above 1500° C. The tensile strength of the fibre drops virtually to zero after the heat treatment at 1500° C. Carbon microcrystals are precipitated from the Si-C random network with excess carbon, and they are distributed uniformly in the fibre. These carbon particles suppress the growth of SiC crystals. It is shown that the carbon microcrystals play an important role in maintaining the high mechanical strength of the SiC fibre.
TL;DR: In this paper, the effect of plastic deformation on tensile properties of quenched commercial β-phase titanium alloys has been investigated at approximately constant grain size and oxygen content.
Abstract: The effect of plastic deformation mode on tensile properties of quenched commercial β-phase titanium alloys has been investigated at approximately constant grain size and oxygen content. In addition, stability of β-phase has been estimated from ω-reflections or diffuse streaking in electron diffraction patterns in a manner similar to the previous works on binary β-phase titanium alloys. Dominant mode of plastic deformation is {332} twinning in the alloys with large instability of β-phase, such as Ti-11.5Mo-6Zr-4. 5Sn and Ti-15Mo-5Zr, and is crystallographic slip in the alloys with small instability of β-phase, such as Ti-15Mo-5Zr-3Al, Ti-3Al-8V-6Cr-4Mo-4Zr, Ti-15V-3Cr-3Al-3Sn, Ti-8Mo-8V-2Fe-3Al, and Ti-13V-11C-3Al. Twinning leads to low yield strength and large elongation, while slip results in high yield strength and small elongation in agreement with binary and termary β-phase titanium alloys.
TL;DR: Mussels and oysters contaminated by the dinoflagellate showed similar toxins, but contained larger proportions of C3 (40-57 mole%) and more potent carbamate toxins (7-23 mole% total).
TL;DR: The extent of oxidation of polyenoic esters of eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) was compared quantitatively with that of ethyl linoleate (Lo) and linolenate (Ln) by oxygen uptake as discussed by the authors.
Abstract: The extent of oxidation of ethyl esters of eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) was compared quantitatively with that of ethyl linoleate (Lo) and ethyl linolenate (Ln) by oxygen uptake and formation of conjugated diene, hydroperoxide and secondary oxidation products. EPA and DHA esters were oxidized rapidly even at 5 C in the dark after an induction period of 3–4 days, while the induction periods of Ln and Lo esters were 20 days and more than 60 days, respectively. Oxygen uptake of EPA and DHA esters after the induction period was 5.2 and 8.5 times faster than that of ethyl Ln, respectively. Hydroperoxides of EPA and DHA esters are much less stable than those of ethyl Lo. The peroxide value is not necessarily a good indication of oxidation in these polyenoic acids because a considerable amount of secondary products is formed at the early stage of oxidation. Polymers were found to be major secondary products in these polyenoic esters.
TL;DR: This article developed an animal model of late asthmatic response (LAR) using guinea pigs and found that 20 of the 50 animals showed a dual LAR response in which the LAR occurred 3 to 6 h after immediate asthasting response (IAR).
Abstract: To elucidate the mechanisms of late asthmatic response (LAR) observed in asthmatic subjects, we have developed an animal model of LAR using guinea pigs. Fifty guinea pigs were immunized with a mixture of Ascaris suum extract and aluminum hydroxide and then challenged with an inhalation of Ascaris suum extract without anesthesia. Twenty of the 50 guinea pigs showed a dual asthmatic response in which the LAR occurred 3 to 6 h after immediate asthmatic response (IAR). Histologic studies by rapid freezing with liquid nitrogen or bronchoalveolar lavage (BAL) were performed in 14 of these 20 guinea pigs with LAR and compared with those in 10 of 18 guinea pigs with only IAR, 10 control guinea pigs, and 10 nonlmmunlzed but challenged guinea pigs. Both the percentage and the absolute number of neutrophils In the SAL fluid of the guinea pigs with LAR were significantly greater than those of the control guinea pigs (p < 0.02) and than those of the nonimmunized but challenged guinea pigs (p < 0.02). However, that of ...
TL;DR: A simple, reproducible method which specifically eliminates the antigenicity of surface class I major histocompatibility complex (MHC) molecules by acid treatment at pH 3 from the membrane of viable cells is described.
TL;DR: The pressure derivative of the Curie temperature d T c /d p of the Heusler alloys Ni 2 MnZ(Z = Al, Ga, In, Sn and Sb) has been obtained from the results of temperature dependence of initial permeability under pressure up to about 6 kbar.
TL;DR: In this article, the effect of coal rank on the product distribution pattern was investigated in Ar at 1037 K with a Curie-point pyrolyser, using seventeen coals ranging from lignite to anthracite.
TL;DR: In this paper, a review is given of organometallic polymers as precursors for ceramic fibres, conversion processes from polymer to ceramic and the mechanical properties of the resulting fibres.
TL;DR: The sequences of the S-glycoproteins from three homozygotes of Brassica campestris show extensive homology and have cysteine-rich clusters and 6–7 oligosaccharide chains.
Abstract: The cruciferous genus Brassica has a self-incompatibility system that is under the sporophytic control of a single locus, S (ref. 1). Although evidence has accumulated that S-locus-specific proteins, termed S-glycoproteins2–4, are strongly associated with the expression of self-incompatibility4–8, their structures and functions are still unknown. This paper reports the sequences of the S-glycoproteins from three homozygotes of Brassica campestris. They show extensive homology. The published DNA sequence data for the S6-glycoprotein of B. oleracea9 can be revised to encode the total sequence of the glycoprotein on the basis of the sequences of S-glycoproteins of B. campestris. These S-glycoproteins have cysteine-rich clusters and 6–7 oligosaccharide chains. There is no homology between the S-glycoproteins of Nicotiana alata10 and those of B. campestris.
TL;DR: Caracterisation de la resistance a la rupture par traction, de la ductilite de flexion and de la durete, de the temperature de cristallisation, of la chaleur de cranchallisation et de la conductivite electrique des alliages amorphes Al-5 a 30% at. X and Al-15 a 40% at.
Abstract: Caracterisation de la resistance a la rupture par traction, de la ductilite de flexion, de la durete, de la temperature de cristallisation, de la chaleur de cristallisation et de la conductivite electrique des alliages amorphes Al-5 a 30% at. Si-5 a 30% at. X et Al-15 a 40% at. Ge-5 a 30% at. X ou X represente Ti, Zr, V, Nb, Cr, Co, Ni, Cu
TL;DR: In this article, the authors used combined high-resolution electron microscopy and computer simulation to achieve the successful incorporation of chains of selenium into a synthetic mordenite, a zeolite which has one-dimensional channels running parallel to its c-axis.
Abstract: One of the disappointments to emerge from the recent intensive study of low-dimensional solids has been the increasing realization that relatively few of the investigated systems exhibit genuine one-or two-dimensional behaviour. Measured electronic and optical properties of crystalline and amorphous low-dimensional solids signify that there is significant interchain or interlayer perturbation. One possible way of eliminating such perturbation in so-called one-dimensional systems is to accommodate individual chains within the pores of a host dielectric material, which, preferentially, should itself be crystalline and well ordered. Here we report the use of combined high-resolution electron microscopy and computer simulation, to achieve the successful incorporation of chains of selenium into a synthetic mordenite, a zeolite which has one-dimensional channels (diameter ∼7 A) running parallel to its c-axis. Remarkably, the uptake of selenium, which converts the white mordenite into an orange colour, occurs in a patchwise fashion leading to domains of occupied channels. The incorporation is readily accomplished thermally, and can be effected with a range of other zeolitic hosts, including ZSM-5, ZSM-23 and zeolites L and Y.
01 Mar 1987
TL;DR: This paper defines a unique system of workspace coordinates and introduces an unique jointspace vector consisting of joint-vectors of the two arms, and forms kinematics and statics for a two-arm robot which is new in this paper.
Abstract: In this paper we discuss the control of cooperating tasks being done by two robotic arms. In order to control those tasks, we extend hybrid position/force control scheme presented thus far by various researchers for a single-arm robot. The point of the extension is formulation of kinematics and statics for a two-arm robot which is new in this paper. We define a unique system of workspace coordinates and, corresponding to the unique workspace, introduce an unique jointspace vector consisting of joint-vectors of the two arms. Using these work and joint spaces, we formulate kinematics and statics. Based upon this formulation, we successfully apply the hybrid scheme to the two-arm robot. A demonstration of the theory working on a real two-arm industrial robot and experimental data of simultaneous control of position and force proves the effectiveness of our method.