Showing papers by "Tohoku University published in 1986"
TL;DR: In this article, a mechanism to generate cosmological baryon number excess without resorting to grand unified theories is proposed, where the lepton number excess originating from Majorana mass terms may transform into the number excess through the unsuppressed baryone number violation of electroweak processes at high temperatures.
3,472 citations
TL;DR: A detailed experimental study has been made to clarify the mechanism of impulsive pressure generation from a single bubble collapsing in a static fluid as discussed by the authors, which is the most essential and important research task concerned with cavitation damage.
Abstract: A detailed experimental study has been made to clarify the mechanism of impulsive pressure generation from a single bubble collapsing in a static fluid – this is the most essential and important research task concerned with cavitation damage. First, the general feature of impulsive pressure generation is discussed, and then the impulsive pressure directly contributing to damage is investigated by various means. As a result, it is found that the impulsive pressure causing plastic deformation of material is closely related, directly or indirectly, to the behaviour of a liquid jet. Further more, it is demonstrated that the interaction of a tiny bubble with a shock wave or a pressure wave must be an important effect in producing a local high pressure which causes damage to material. The damage pit caused by the bubble-shock-wave interaction essentially results from the impact pressure from a liquid microjet.
549 citations
TL;DR: In this paper, a review of recent research work on the preparation, the crystal structure, the band structure, electrical and optical properties, and the superconductivity of black phosphorus is presented.
Abstract: Black phosphorus is a narrow-gap semiconductor newly attracting attention because of recent success in growing single crystals at a high temperature under a high pressure. This review covers recent research work on the preparation, the crystal structure, the band structure, the electrical and optical properties, and the superconductivity of black phosphorus.
520 citations
TL;DR: In this paper, the power spectrum of the vacuum noise seen by a uniformly accelerated observer in flat spacetimes of arbitrary dimensions is investigated and the phenomenon of apparent inversion of statistics in odd dimensions is explained.
Abstract: This is a comprehensive account of a particular recent development concerning the thermal character inherent in the quantum field as viewed from a uniformly accelerated frame of reference. That is, the power spectrum of the vacuum noise (or the detector-response function) seen by a uniformly accelerated observer in flat spacetimes of arbitrary dimensions is investigated and is shown to exhibit the phenomenon of the apparent inversion of statistics in odd dimensions. Its relation to the thermalization theorem is clarified. Also discussed are the closely related phenomena occurring in the vacuum stress of the Rindler manifold and in the noise seen by a comoving observer in the de Sitter spacetime, as well as those associated with the circular motion in the flat spacetime.
473 citations
TL;DR: In this paper, the eutectoid and peritectoid reactions were not observed for near-equiatomic and Ni-rich TiNi alloys, and the precipitation sequence can be written asβ 0 → Ti11Ni14 → Ti2Ni3 → TiNi3.
Abstract: Metallographic studies have been made of precipitation processes in Ti-50 pct Ni and Ti-52 pct Ni (at. pct) shape memory alloys. The eutectoid and peritectoid reactions previously reported for near-equiatomic and Ni-rich TiNi alloys were not observed for either composition. In the Ti-52Ni alloy, diffusional transformations take place, similar to those in supersaturated alloys. The precipitation sequence can be written asβ
0 → Ti11Ni14 → Ti2Ni3 → TiNi3. The solidus line of the TiNi phase in the Ti-52Ni alloy lies at 812 ± 22 °C. Morphological characteristics of the various precipitate phases are described in detail.
409 citations
TL;DR: In this article, the authors presented matrix formulations for the discrete-ordinate and matrix-operator methods of solving the transfer of solar radiation in a plane-parallel scattering atmosphere, where eigenspace transformations of symmetric matrices are introduced into the method of Stamnes and Swanson instead of using the decomposition of an asymmetric matrix.
Abstract: Matrix formulations are presented for the discrete-ordinate and the matrix-operator methods of solving the transfer of solar radiation in a plane-parallel scattering atmosphere. Eigenspace transformations of symmetric matrices are introduced into the method of Stamnes and Swanson instead of using the decomposition of an asymmetric matrix. The computational stability is considerably improved by this algorithm, especially for single-precision calculations. Representations of the reflection and transmission matrices in the matrix-operator method are also given, in terms of the indicated formulations, by considering a boundary-value problem of the discrete-ordinate method. The solutions of the discrete-ordinate method for inhomogeneous atmospheres are given by combining discrete-ordinate solutions for respective homogeneous sublayers through the addition technique of the matrix-operator method.
381 citations
TL;DR: The protein sequence deduced from the nucleotide sequence of the cloned cDNA shows significant similarity to the entire region of Neurospora tyrosinase, a pigment cell-specific cDNA clone from a B16 mouse melanoma cDNA library by differential hybridization.
Abstract: We have isolated a pigment cell-specific cDNA clone from a B16 mouse melanoma cDNA library by differential hybridization. The mRNA of isolated cDNA is highly expressed in B16 melanoma cells and in black mouse (C57BL/6) skin, but is not detectable in mouse neuroblastoma cells nor in K1735 mouse amelanotic melanoma cells. The protein sequence deduced from the nucleotide sequence of the cloned cDNA shows significant similarity to the entire region of Neurospora tyrosinase. To know the identity of cDNA, we transfected K1735 amelanotic melanoma and COS-7 cells with the cDNA carried in a simian virus 40 vector (pKCRH2). We confirmed that the isolated cDNA encodes mouse tyrosinase by immunofluorescence staining of transfected cells using two different anti-T4-tyrosinase monoclonal antibodies. Tyrosinase is composed of 513 amino acids with a molecular weight of 57,872 excluding a hydrophobic signal peptide of 24 amino acids.
226 citations
TL;DR: In this paper, it was shown that the two species cannot coexist and undergo transmetalation reactions at low temperature, but they exhibit new and unique reactivities and selectivities: in conjugate additions, e.g., not only activation but also high regio-, stereo-, and chemo-selectivity as well as very high asymmetric induction.
Abstract: Organometallic compounds with pronounced nucleophilicity such as organocopper and organolithium compounds, and powerful electrophiles, such as BF3 and AlCl3, are generally thought to be incompatible under normal, homogeneous reaction conditions. As a matter of course, it is anticipated that the two species cannot coexist and undergo transmetalation reactions. To our surprise, however, RCu and BF3 are compatible at low temperature. RCu·BF3 and related organocopper-Lewis acid reagents exhibit new and unique reactivities and selectivities: in conjugate additions, e.g., not only activation but also high regio-, stereo-, and chemo-selectivity as well as very high asymmetric induction is observed; allylic derivatives are alkylated regioselectively, and reaction towards carbonyl groups, imines, epoxides, aziridines, ethers, acetals, orthoformates, and pyridinium salts is in each case found to be selective. RLi·BF3 and related organolithium-Lewis acid reagents also exhibit noteworthy selectivities and reactivities. These complex reagents are utilized in the key steps of the total synthesis of many important natural products, such as certain terpenes, steroids, and alkaloids.
213 citations
TL;DR: In this article, a simple variational calculation of the ground state properties of the electron-hole system confined in three-dimensional quantum wells with spherical shape is presented, where the radius of the wall is reduced to a few times the effective Bohr radius of a bulk exciton.
207 citations
TL;DR: Five days after ischemic insult, pyramidal cells and L-glutamate binding sites in the CA1 region ipsilateral to the KA injection were preserved in spite of neuronal necrosis and a significant decrease in L- glutamate receptor density in the contralateralCA1 region, indicating the critical role of Schaffer collaterals in delayed neuronal death.
194 citations
TL;DR: In this article, the Raman spectra of indole, skatole, tryptophan and its derivatives including C4-monodeuterated triedophan were studied with special attention to the origin of the band around 1350 cm−1.
TL;DR: The upper boundary of the descending oceanic plate is located by using PS-waves (converted from P to S at the boundary) in the Tohoku District, the north-eastern part of Honshu, Japan as mentioned in this paper.
Abstract: Summary. The upper boundary of the descending oceanic plate is located by using PS-waves (converted from P to S at the boundary) in the Tohoku District, the north-eastern part of Honshu, Japan. The observed PS-P time data are well explained by a two-layered oceanic plate model composed of a thin low-velocity upper layer whose thickness is less than 10 km and a thick high-velocity lower layer; the upper and lower layers respectively have 6 per cent lower and 6 per cent higher velocity than the overriding mantle. The estimated location of the upper boundary is just above the upper seismic plane of the double-planed deep seismic zone. This result indicates that events in the upper seismic plane, at least in the depth range from 60 to 150 km, occur within the thin low-velocity layer on the surface of the oceanic plate.
TL;DR: In this paper, the structural and crystallography of a stress-induced plate in metastable β titanium alloys was investigated by a combination of two surface trace analysis and transmission electron microscopy, and it was found that there were two types of {332} 〈113〉 twinning, depending on whether one variant ofω phase was preferentially induced in a twin or not.
Abstract: Microstructure and crystallography of a stress-induced plate in metastableβ titanium alloys, Ti-V, Ti-Mo, Ti-Nb, Ti-Fe, were investigated by a combination of two surface trace analysis and transmission electron microscopy. Stress-inducedω phase transformation or {332} 〈113〉 twinning appeared in circumstances whereβ phase was very unstable. It was found that there were two types of {332} 〈113〉 twinning, depending on whether one variant ofω phase was preferentially induced in a twin or not. Stress-inducedω phase not relating to {332} 〈113〉 twinning was not observed in matrix. This suggests that stress-inducedω phase transformation is accompanied with {332} 〈113〉 twinning. Preferential formation of oneω variant was influenced not only by alloy system and its composition, but also by cooling rate from solution treatment temperature. The relation between athermalω structure and stress-inducedω phase transformation or plastic deformation mode is also discussed.
TL;DR: Recherche de l'origine veritable de la toxine marine tetrodotoxine produite par une bacterie Pseudomonas sp. provenant of l'algue Jania sp.
Abstract: Recherche de l'origine veritable de la toxine marine tetrodotoxine produite par une bacterie Pseudomonas sp. provenant de l'algue Jania sp.
TL;DR: Pectenotoxin-1, a non-diarrheagenic toxin from diarrhetic shellfish poisoning causative mussels, resulted in no abnormalities in the small intestine, but did cause characteristic liver injuries, and numerous non-fatty vacuoles appeared in the hepatocytes around the periportal regions of the hepatic lobules.
TL;DR: In this paper, normal coordinate calculations have been performed for indole and 11 deuterated indoles and the set of valence force constants obtained is able to reproduce i.r. and Raman frequencies with an average error of about 6 cm−1.
TL;DR: Protoplasts isolated from suspension cultures of rice cells were treated with bacterial plasmid DNA carrying a chimaeric gene consisting of the nopaline synthase promoter, the aminoglycoside phosphotransferase II (APH(3′)II) structural gene from bacterial transposon Tn5 and the terminator region from cauliflower mosaic virus DNA.
Abstract: Protoplasts isolated from suspension cultures of rice cells were treated with bacterial plasmid DNA carrying a chimaeric gene consisting of the nopaline synthase promoter, the aminoglycoside phosphotransferase II (APH(3′)II) structural gene from bacterial transposon Tn5 and the terminator region from cauliflower mosaic virus DNA. Colonies capable of proliferating in medium containing kanamycin (100 μg/ml) were selected. A transformation frequency of approximately 2% to 3% was recorded in several experiments. The enzyme (APH(3′)II) was also detected in kanamycin-resistant callus, which had survived after repeated selection. There was some variation in the APH(3′)II activity in the transformants which paralleled the copy number of the inserted genes.
TL;DR: In this article, the authors calculated the upper critical field of superconducting superlattices by taking account of spatial variations of the following quantities of conduction electrons: the density of states, the diffusion constant, the attractive interaction constant responsible for superconductivity, and the spin polarization.
Abstract: The upper critical field of superconducting superlattices is calculated by taking account of spatial variations of the following quantities of conduction electrons: the density of states, the diffusion constant, the attractive interaction constant responsible for superconductivity, and the spin polarization. For applied magnetic fields parallel to the layers, these spatial variations cause a dimensional crossover in the temperature dependence of the upper critical field ${H}_{c2?}$. The spatial variation of the density of states is most important for the effect of the dimensional crossover observed in Nb/Cu superlattices. For applied magnetic fields perpendicular to layers, a new type of crossover is predicted in the temperature dependence of ${H}_{c2\ensuremath{\perp}}$ for superlattices composed of a high-${H}_{c2}$ material and a low-${H}_{c2}$ material. The anisotropic spin polarization of conduction electrons induced by applied magnetic fields explains the anomalous behavior of ${H}_{c2}$ observed in V/Ni superlattices.
Journal Article•
TL;DR: In this paper, the influence of intergranular hydrogen embrittlement on the mechanical behavior and fracture behavior of Co3Ti and 0.1 wt% B-doped compounds were studied.
TL;DR: In this paper, the Majoron transmutes itself into the invisible axion as a soft symmetry breaking parameter, and some consequences of this idea are discussed, including a suggestion that the origin of the baryon symmetry of the Universe is connected with an induced lepton number asymmetry produced at temperatures of order VPQ and the possibility that νμ→ντ oscillations may be observable at accelerators.
Abstract: Physical arguments involving the solar neutrino problem are given which connect the scale of U(1)PQ breakdown with that of the spontaneous breakdown of lepton number. In the simplest model, the Majoron transmutes itself into the invisible axion as a soft symmetry breaking parameter is turned on. Some consequences of this idea are discussed. These include a suggestion that the origin of the baryon symmetry of the Universe is connected with an induced lepton number asymmetry produced at temperatures of order VPQ and the possibility that νμ→ντ oscillations may be observable at accelerators.
TL;DR: In this paper, a steam gasification of calcium-loaded Yallourn coal has been carried out with a thermobalance, and it was shown that the interconversion between calcium carbonate and oxide takes place readily in the gasification temperature region.
TL;DR: The electrical conductivity of the redoped polythiophene films was in the range 2 × 10 2 − 5.9 S cm −1, where S is the number of conjugated coplanar segments.
01 Jul 1986
TL;DR: In this paper, the crystal structure of a synthetic ZrO2 has been studied in situ up to 51 kbar at room temperature, where the directions of the b and c axes are preserved through the transition and the transformation is displacive.
Abstract: Combining a miniature diamond-anvil pressure cell with a single crystal four-circle diffractometer, the crystal structure of a synthetic ZrO2 has been studied in situ up to 51 kbar at room temperature. The space group of the unquenchable orthorhombic high pressure phase is Pbcm. The directions of the b and c axes are preserved through the transition and the transformation is displacive. The coordination configurations of the Zr atoms and oxygen atoms are the same in the high pressure and low pressure phases. The orthorhombic high pressure phase has a higher entropy than that of low pressure monoclinic phase.
TL;DR: In this article, the authors focused on the classification of waters based on the temperature-salinity (T-S) scatter diagram analyses, and on the extraction of the mean state of their distribution for each season.
Abstract: We analyzed hydrographic data obtained monthly by the Iwate Prefectural Fisheries Laboratory during 1977–1981. Our attention was focussed on the classification of waters based on the Temperature-Salinity (T-S) scatter diagram analyses, and on the extraction of the “mean state” of their distribution for each season. The “water system” was defined as “all waters occupying some specific region on the T-S plane”, and the mean state for each season was expressed by the distribution of the “mode water systems” (i.e., the most commonly occuring water system). Because of the coexistence of the Tsugaru Warm Current, the Oyashio and the Kuroshio, and their large seasonal variability, the sea waters had a wide variety of T-S combinations. The detailed T-S scatter diagram analyses allowed us to classify the waters into six water systems. A time-longitude diagram of water systems and the distribution of mode water systems are presented. The latter showed clear seasonal variations of the Tsugaru Warm Current and the Oyashio. Though the water system analysis was successfully able to present the distribution of the various waters in the Sanriku Coastal Area and to clearly extract the mean state of sea conditions, it was found that the classification of water systems on the T-S plane was not complete in all cases for this area.
TL;DR: Using the Schwinger-Dyson gap equation, a chiral condensate is discussed in theories having a slowly varying running-coupling constant as mentioned in this paper, and it is shown that if the coupling strength λ remains close to a certain critical value λc up to a large scale Λ, a Chiral Condensate may occur with the hierarchic nature σ(0)/Λ ≈ exp[ − π/(λ − λ c ) 1 2 ], σ (0) being the fermion d ynamical mass at zero
TL;DR: The toxic principle in mussels collected in France, Sweden, the Netherlands, and Spain that caused diarrhetic shellfish poisoning was identified to be okadaic acid by its chromatographic properties and spectral data as mentioned in this paper.
Abstract: The toxic principle in mussels collected in France, Sweden, the Netherlands, and Spain that caused diarrhetic shellfish poisoning was identified to be okadaic acid by its chromatographic properties and spectral data.
TL;DR: High-statistics data from two exposures of the BNL 7-foot deuterium bubble chamber to a wide-band-neutrino beam with an average energy of 1.6 GeV were analyzed for exclusive pion production in charged-current neutrino-deuterium interactions to present new results for single-pion and multipion production.
Abstract: High-statistics data from two exposures of the BNL 7-foot deuterium bubble chamber to a wide-band-neutrino beam with an average energy of 1.6 GeV were analyzed for exclusive pion production in charged-current neutrino-deuterium interactions. For the single-pion production reactions, the properties of ${\ensuremath{\Delta}}^{++}$ production and decay as well as the final results of an isospin analysis are presented. New results for single-pion and multipion production are also presented.
TL;DR: The age-related decrease in PRA is not due to the change in PRSC, but is mainly due to a fall in ARC, which might be responsible in part for the reduced ARC in the elderly.
Abstract: To investigate the effect of aging on the renin-angiotensin-aldosterone system, plasma renin substrate concentrations (PRSC); plasma total, active, and inactive renin concentrations (TRC, ARC, and IRC); PRA; and plasma aldosterone concentrations (PAC) were measured simultaneously in 60 normal subjects, 18-84 yr old. PRSC was measured by the addition of excess human renal renin. ARC and TRC after trypsin activation were measured by adding sheep renin substrate; IRC was calculated by subtracting ARC from TRC. The active renin ratio was calculated as follows: ARC/TRC X 100%. PRA and PAC were measured by RIA. There were no significant changes in PRSC, TRC, IRC, and PRA to PAC ratio with aging. Both ARC and active renin ratio fell significantly with aging (r = 0.46 and P less than 0.01; and r = 0.54 and P less than 0.01, respectively). PRA and PAC also tended to decrease with aging (r = 0.35 and P less than 0.01; and r = 0.59 and P less than 0.01, respectively). A significant positive correlation was found between PRA and ARC (r = 0.72; P less than 0.001). PRA was also correlated with PAC. In conclusion, the age-related decrease in PRA is not due to the change in PRSC, but is mainly due to the fall in ARC. Decreased conversion of inactive to active renin might be responsible in part for the reduced ARC in the elderly.
TL;DR: Increases in urinary Na excretion and osmolar clearances were associated with a rise in plasma alpha hANP after water loading and hypertonic saline infusion, but changes in urine flow were mainly associated with alterations in AVP release.
Abstract: A new specific RIA for a-human atrial natriuretic hormone (ahANP) was used to determine whether changes in plasma volume elicited by acute water loading, hypertonic saline infusion, and furosemide administration caused changes in ANP release and resultant changes in renal and cardiovascular function in normal subjects. In addition, changes in plasma arginine vasopressin (AVP), PRA, and aldosterone concentrations were studied simultaneously. Mean plasma ahANP and AVP levels were 51.3 ± 16.0 (±SE) and 3.1 ± 0.6 pg/ml, respectively, in the basal state. Plasma ahANP rose to 77.8 ± 27.6 in response to a 4.5% increase in plasma volume induced by water loading, increased further to 134.1 ± 28.9 in response to a 23% volume increase induced by hypertonic saline, and fell to 70.2 ± 15.8 pg/ml in response to a decrease in plasma volume after furosemide treatment (P 〈 0.01–0.05). On the other hand, plasma AVP fell to 1.8 ± 0.1 pg/ml after the water load, rose to 4.1 ± 0.6 after hypertonic saline, and rose further to ...