Showing papers by "Tohoku University published in 1997"
TL;DR: It is demonstrated that Nrf2 is essential for the transcriptional induction of phase II enzymes and the presence of a coordinate transcriptional regulatory mechanism for phase II enzyme genes and the nrf2-deficient mice may prove to be a very useful model for the in vivo analysis of chemical carcinogenesis and resistance to anti-cancer drugs.
3,557 citations
TL;DR: In this paper, the authors reported the observation of optically pumped lasing in ZnO at room temperature using a plasma-enhanced molecular beam epitaxy on sapphire substrates.
Abstract: We report the observation of optically pumped lasing in ZnO at room temperature. Thin films of ZnO were grown by plasma-enhanced molecular beam epitaxy on (0001) sapphire substrates. Laser cavities formed by cleaving were found to lase at a threshold excitation intensity of 240 kW cm−2. We believe these results demonstrate the high quality of ZnO epilayers grown by molecular beam epitaxy while clearly demonstrating the viability of ZnO based light emitting devices.
2,126 citations
TL;DR: In this paper, a direct approach to calculate the phonon dispersion using an ab initio force constant method was introduced, where the authors derived the force constants from the Hellmann-Feynman forces induced by the displacement of an atom in the fcc supercell.
Abstract: A direct approach to calculate the phonon dispersion using an ab initio force constant method is introduced. The phonon dispersion and structural instability of cubic ${\mathrm{ZrO}}_{2}$ are found using a supercell method in the local-density approximation. The force constants are determined from the Hellmann-Feynman forces induced by the displacement of an atom in the $2\ifmmode\times\else\texttimes\fi{}2\ifmmode\times\else\texttimes\fi{}2$ fcc supercell. This size of the supercell gives ``exact'' phonon frequencies at $\ensuremath{\gamma},X,L,W$ Brillouin zone points. The phonon dispersion curves show a pronounced soft mode at the $X$ point, in agreement with the experimentally observed cubic to tetragonal phase transition.
2,122 citations
TL;DR: The high expression level of HLF mRNA in the O2 delivery system of developing embryos and adult organs suggests that in a normoxic state, HLF regulates gene expression of VEGF, various glycolytic enzymes, and others driven by the HRE sequence, and may be involved in development of blood vessels and the tubular system of lung.
Abstract: We have isolated and characterized a cDNA for a novel Per-Arnt/AhR-Sim basic helix–loop–helix (bHLH-PAS) factor that interacts with the Ah receptor nuclear translocator (Arnt), and its predicted amino acid sequence exhibits significant similarity to the hypoxia-inducible factor 1α (HIF1α) and Drosophila trachealess (dTrh) gene product. The HIF1α-like factor (HLF) encoded by the isolated cDNA bound the hypoxia-response element (HRE) found in enhancers of genes for erythropoietin, vascular endothelial growth factor (VEGF), and various glycolytic enzymes, and activated transcription of a reporter gene harboring the HRE. Although transcription-activating properties of HLF were very similar to those reported for HIF1α, their expression patterns were quite different between the two factors; HLF mRNA was most abundantly expressed in lung, followed by heart, liver, and other various organs under normoxic conditions, whereas HIF1α mRNA was ubiquitously expressed at much lower levels. In lung development around parturition, HLF mRNA expression was markedly enhanced, whereas that of HIF1α mRNA remained apparently unchanged at a much lower level. Moreover, HLF mRNA expression was closely correlated with that of VEGF mRNA. Whole mount in situ hybridization experiments demonstrated that HLF mRNA was expressed in vascular endothelial cells at the middle stages (9.5 and 10.5 days postcoitus) of mouse embryo development, where HIF1α mRNA was almost undetectable. The high expression level of HLF mRNA in the O2 delivery system of developing embryos and adult organs suggests that in a normoxic state, HLF regulates gene expression of VEGF, various glycolytic enzymes, and others driven by the HRE sequence, and may be involved in development of blood vessels and the tubular system of lung.
1,035 citations
TL;DR: In this article, the major and minor elements, including C and S, were analyzed for the Ramah Group sedimentary rocks in northeastern Labrador, Canada, to elucidate weathering processes on the Earth's surface about 1.9 Ga ago.
756 citations
TL;DR: Results indicate that cytosolic PLA2 plays a non-redundant role in allergic responses and reproductive physiology and is activated by submicromolar concentrations of Ca2+ ions and by phosphorylation by mitogen-activated protein kinases (MAP kinases).
Abstract: Phospholipase A2 (PLA2) comprises a superfamily of enzymes that hydrolyse the ester bond of phospholipids at the sn-2 position1,2,3. Among the members of this superfamily, cytosolic PLA2 has attracted attention because it preferentially hydrolyses arachidonoyl phospholipids and is activated by submicromolar concentrations of Ca2+ ions and by phosphorylation by mitogen-activated protein kinases (MAP kinases)4,5,6,7,8. Here we investigate the function of cytosolic PLA2 in vivo by using homologous recombination to generate mice deficient in this enzyme. These mice showed a marked decrease in their production of eicosanoids and platelet-activating factor in peritoneal macrophages. Their ovalbumin-induced anaphylactic responses were significantly reduced, as was their bronchial reactivity to methacholine. Female mutant mice failed to deliver offspring, but these could be rescued by administration of a progesterone-receptor antagonist to the mother at term. Considered together with previous findings9,10,11,12,13,14,15, our results indicate that cytosolic PLA2 plays a non-redundant role in allergic responses and reproductive physiology.
680 citations
TL;DR: In this article, the four methylene bridges of p-tert-butylcalix[4]arene are replaced by sulfide linkages, which can be easily synthesized in a single step (54%) by heating a mixture of ptertbutylphenol, elemental sulfur S8 and NaOH in tetraethylene glycol dimethyl ether with concomitant removal of the resulting hydrogen sulfide.
523 citations
TL;DR: In this paper, an attempt was made to prepare porous carbon by using the channels of Y zeolite as a template, where poly(acrylonitrile) and poly(furfuryl alcohol) were carbonized in the channels and the resultant carbon/zeolite complexes were subjected to acid treatment in order to extract carbon from the ZO framework.
Abstract: An attempt was made to prepare porous carbon by using the channels of Y zeolite as a template. Poly(acrylonitrile) and poly(furfuryl alcohol) were carbonized in the zeolite channels and the resultant carbon/zeolite complexes were subjected to acid treatment in order to extract carbon from the zeolite framework. In addition, pyrolytic carbon deposition in the channels was carried out by exposing the zeolite to propylene at high temperature, and then the carbon was liberated in the same manner as above. The morphology and structure of the carbon prepared in the channels were characterized, and the results were discussed in relation to the morphology and structure of the original zeolite template. It was found that the microscopic morphology of the resultant carbons reflects that of the corresponding zeolites. All of these carbons are highly porous, and some of the CVD carbons have BET surface areas as high as >2000 m2/g.
516 citations
TL;DR: In this paper, the size dependence of the crystal phase of the Co fine particles was investigated, and it was shown that the stabilization of crystal phase is the intrinsic effect caused by the small dimensionality of fine particles.
Abstract: We have synthesized Co fine particles with the average diameter $(D)$ of less than 500 \AA{} by sputtering Co in a somewhat high inert-gas pressure. It has been found that there is a close relationship between the particle size and the crystal phase; that is, pure fcc (\ensuremath{\beta}) phase for $Dl~200\AA{},$ a mixture of hcp (\ensuremath{\alpha}) and \ensuremath{\beta} phases for $D\ensuremath{\sim}300\AA{},$ and \ensuremath{\alpha} phase with inclusion of a very small amount of \ensuremath{\beta} phase for $Dg~400\AA{}.$ Precise structural characterizations have revealed that the \ensuremath{\beta} particles are multiply twinned icosahedrons and the \ensuremath{\alpha} particles are perfect single crystals with external shape of a Wulff polyhedron. In order to explain the size effect on the crystal phase of Co fine particles, we have performed theoretical calculations for total free energies of an \ensuremath{\alpha} single crystal, a \ensuremath{\beta} single crystal, and a multiply twinned \ensuremath{\beta} icosahedron. The present calculations well explain the size dependence of the crystal phase of the Co fine particles, and have revealed that the stabilization of \ensuremath{\beta} phase, confirmed by previous studies, is the intrinsic effect caused by the small dimensionality of fine particles. Moreover, the phase transformations that occurred in annealing experiments can also be explained by the theory.
452 citations
TL;DR: The relationship between the decline in nocturnal blood pressure and mortality was examined and was more pronounced for cardiovascular than for noncardiovascular mortality, and did not change after the data were adjusted for 24-h, daytime, and nighttime blood pressure levels.
433 citations
TL;DR: Results suggest that P450RA regulates the intracellular level of RA and may be involved in setting up the uneven distribution of active RA in mammalian embryos.
Abstract: Retinoic acid (RA) is a physiological agent that has a wide range of biological activity and appears to regulate developmental programs of vertebrates. However, little is known about the molecular basis of its metabolism. Here we have identified a novel cytochrome P450 (P450RA) that specifically metabolizes RA. In vitro, P450RA converts all-trans RA into 5,8-epoxy all-trans RA. P450RA metabolizes other biologically active RAs such as 9-cis RA and 13-cis RA, but fails to metabolize their precursors, retinol and retinal. Overexpression of P450RA in cell culture renders the cells hyposensitive to all-trans RA. These functional tests in vitro and in vivo indicate that P450RA inactivates RA. The P450RA gene is not expressed uniformly but in a stage- and region-specific fashion during mouse development. The major expression domains in developing embryos include the posterior neural plate and neural crest cells for cranial ganglia. The expression of P450RA, however, is not necessarily inducible by excess RA. These results suggest that P450RA regulates the intracellular level of RA and may be involved in setting up the uneven distribution of active RA in mammalian embryos.
TL;DR: It is suggested that microphthalmia-associated transcription factor (MITF) is sufficient to direct pigment cell-specific transcription of the tyrosinase and TRP-1 genes but not theTRP-2 gene.
TL;DR: In this paper, the effects of pH and moisture content on high-solids sludge digestion were investigated using a mesophilic batch digester fed with sludge cake, and the experiments were carried out by changing the initial moisture contents from 90 to 96% and the initial pH from 5.6-7.8 with an optimum of pH 6.3.
TL;DR: In this article, the authors studied the glucose decomposition kinetics in subcritical and supercritical water for the temperatures 573, 623, and 673 K, pressures between 25 and 40 MPa, and residence times between 0.02 and 2...
Abstract: Glucose decomposition kinetics in subcritical and supercritical water were studied for the temperatures 573, 623, and 673 K, pressures between 25 and 40 MPa, and residence times between 0.02 and 2 ...
TL;DR: In this article, a field electron emitter from hollow, open-ended carbon nanotubes has been made, which can emit electrons by tunnelling effects in electric fields, with their small size, small energy spread, high current density and no requirement for heat.
Abstract: Electron guns are indispensable devices that are widely used in household and industrial appliances. Field electron-emitting sources (which emit electrons by tunnelling effects in electric fields), with their small size, small energy spread, high current density and no requirement for heat, have distinct advantages over thermionic emitters. We have made a field electron emitter from hollow, open-ended carbon nanotubes.
TL;DR: The early but dissociative induction of VEGF between neuronal and pial cells suggests different roles of the protein in their cells after transient MCA occlusion.
Abstract: Background and Purpose Vascular endothelial growth factor (VEGF) is a mitogen for endothelial cells and also has the potential to increase vascular permeability. Therefore, it may contribute to the recovery of brain cells from ischemic insult through potentiating neovascularization or may exacerbate brain damage by forming brain edema. However, the exact role of this protein in cerebral ischemia is not fully understood. We investigated temporal, spatial, and cellular profiles of the induction of VEGF gene expression after transient focal cerebral ischemia at both mRNA and protein levels. Methods We used a transient middle cerebral artery (MCA) occlusion model. Northern blot analysis was performed to assess the chronological pattern of induction and the impact of length of ischemia on mRNA expression. Western blot analysis was performed to ensure the selective detection of immunoreactive VEGF with an antibody. Temporal, spatial, and cellular changes of immunohistochemical VEGF expression were compared with...
TL;DR: In this article, the authors present a model describing ionic electrical conduction in porous media, with particular emphasis given to surface conduction, and derive the fractional occupancies of positive, negative, and neutral sites on the surface, and the fraction fractional ionic diffuse layer densities, as a function of the salinity and the pH.
Abstract: We present a model describing ionic electrical conduction in porous media, with particular emphasis given to surface conduction. The porous medium is assumed to consist of an insulating matrix and an interconnected pore volume that is saturated with an electrolyte. When in contact with an electrolyte, mineral surfaces get an excess of charge that is balanced by mobile ions in an electrical diffuse layer above the surface. Electrical conduction in this diffuse layer can contribute substantially to the effective electrical conductivity of the porous medium. Our surface conduction model is based on a description of surface chemical reactions and electrical diffuse layer processes. For this purpose, we consider an amphoteric mineral surface described by a five-site-type model. We derive the fractional occupancies of positive, negative, and neutral sites on the surface, and the fractional ionic diffuse layer densities, as a function of the salinity and the pH. Finally, the specific surface conductance used to describe the surface electrical conduction is related to the previously mentioned properties, via the electrical surface potential, and is found to be dependent on the electrolyte concentration and pH.
TL;DR: In this paper, the origins of hardening in the artificially aged alloys Al1.1Cu 1.7Mg(0.1Ag) are presented.
TL;DR: The glass-forming ability of a Pd 4 Cu 30 Ni 10 P 20 alloy was found to increase significantly by B 2 O 3 flux treatment, as is evidenced by the decrease in the critical cooling rate from 1.57 K/s in the non-fluxed state to 0.100 K/m in the fluxed state as mentioned in this paper.
Abstract: The glass-forming ability of a Pd 4 Cu 30 Ni 10 P 20 alloy was found to increase significantly by B 2 O 3 flux treatment, as is evidenced by the decrease in the critical cooling rate from 1.57 K/s in the non-fluxed state to 0.100 K/s in the fluxed state. The flux treatment also causes the extension of the supercooled liquid region by the increase in the onset temperature of crystallization (T x ). The effect of the flux treatment is presumably due to the increase in the thermal stability of the supercooled liquid by the suppression of heterogeneous nucleation. The critical cooling rates in the non-fluxed and fluxed states for a Pd 40 Ni 40 P 20 alloy are measured to be 128 and 0.167 K/s, respectively, both of which are larger than those for the Pd-Cu-Ni-P alloy. The use of the molten Pd-Cu-Ni-P alloy subjected to the flux treatment enabled the production of bulk amorphous alloys in cylindrical forms of 50 to 72 mm in diameter and 52 to 75 mm in length. The glass transition temperature (T g ) and T x values of the bulk amorphous alloys are the same as those for the melt-spun amorphous ribbon prepared from the fluxed molten alloy. The success of synthesizing an amorphous alloy of 72 mm in diameter is encouraging both for the future development of basic science of bulk amorphous alloys and for their engineering application.
TL;DR: Targets for improving rice yield potential are discussed with a focus on the role of increased photosynthesis efficiency in relation to leaf N status and the photosynthetic components in the leaves.
Abstract: Characteristics of rice (Oryza sativa) as a crop plant are briefly introduced, and the relationship between formation of yield potential and nitrogen (N) nutrition is described on the basis of studies using 15N as a tracer In addition, the relationship between the leaf photosynthetic capacity and leaf N, and the factors limiting leaf photosynthesis under different growth conditions are reviewed Finally, targets for improving rice yield potential are discussed with a focus on the role of increased photosynthesis efficiency in relation to leaf N status and the photosynthetic components in the leaves
TL;DR: Phylogenetic analysis of the chloroplast-encoded rbcL gene in Leguminosae are consistent with previous hypotheses in suggesting that the family as a whole is monophyletic, but that only two of its three subfamilies are natural.
Abstract: Phylogenetic analysis of the chloroplast-encoded rbcL gene in Leguminosae are consistent with previous hypotheses in suggesting that the family as a whole is monophyletic, but that only two of its three subfamilies are natural. The earliest dichotomies in the family appear to have involved tribes Cercideae or Cassieae (subtribe Dialiinae), followed by Detarieae/ Macrolobieae, all of which are members of subfamily Caesalpinioideae. The remainder of the family is divided into two clades: (1) Mimosoideae and the caesalpinioid tribes Caeasalpinieae and Cassieae (subtribes Ceratoniinae and Cassiinae); (2) Papilionoideae. Basal groups within Papilionoideae are, as expected, elements of the grade tribes Sophoreae and Swartzieae. Major clades within Papilionoideae include: (1) a Genistoid Alliance comprising Genisteae, Crotalarieae, Podalyrieae, Thermopsideae, Euchresteae, and also some Sophoreae; (2) a clade marked by the absence of one copy of the chloroplast inverted repeat, with which are associated Robinieae. Loteae, and some Sophoreae; (3) Phaseoleae, Desmodieae. Psoraleeae, and most Millettieae, a group also marked by presence of pseudoracemose inflorescences; and (4) a well-supported clade comprising Aeschynomeneae, Adesmieae, and some Dalbergieae. Nodulation is most parsimoniously optimized on the rbcL strict consensus tree as three parallel gains, occurring in Papilionoideae, the caesalpioioid ancestors of Mimosoideae, and in the genus Chamaecrista (Caesalpinieae: Cassieae).
TL;DR: In vivo nicotinamide or aminoguanidine treatment of prediabetic ZDF rats prevented the iNOS expression in islets and decreased beta cell dysfunction while blocking beta cell destruction and hyperglycemia, concluding that NO-lowering agents prevent adipogenic diabetes in obese rats.
Abstract: Here we report that free fatty acid-induced suppression of insulin output in prediabetic Zucker diabetic fatty (ZDF) rats is mediated by NO. When normal islets were cultured in 2 mM FFA, NO production and basal insulin secretion increased slightly. In cultured prediabetic ZDF islets, FFA induced a fourfold greater rise in NO, upregulated mRNA of inducible nitric oxide synthase (iNOS), and reduced insulin output; both nicotinamide and aminoguanidine, which lower NO, prevented the FFA-mediated increase in iNOS mRNA, reduced NO, and minimized the loss of insulin secretion. In vivo nicotinamide or aminoguanidine treatment of prediabetic ZDF rats prevented the iNOS expression in islets and decreased beta cell dysfunction while blocking beta cell destruction and hyperglycemia. We conclude that NO-lowering agents prevent adipogenic diabetes in obese rats.
TL;DR: The present study shows an elevation of exhaled CO in asthmatic patients that decreases with corticosteroid therapy, and increases in the exhaled carbon monoxide levels therefore may reflect inflammation in theAsthmatic lung.
Abstract: Exhaled carbon monoxide (CO) concentrations were measured on a CO monitor by vital capacity maneuvers in asthmatic patients receiving or not receiving inhaled corticosteroids and in nonsmoking and smoking healthy control subjects. CO was detectable and measured reproducibly in the exhaled air of all subjects. The exhaled CO concentrations were higher in asthmatic patients not receiving inhaled corticosteroids (5.6 ± 0.6 ppm, p < 0.001) and similar in asthmatic patients receiving inhaled corticosteroids (1.7 ± 0.1 ppm) compared with those in nonsmoking healthy control subjects (1.5 ± 0.1 ppm). Smoking healthy control subjects had the highest levels of exhaled CO concentration among the groups (21.6 ± 2.8 ppm, p < 0.001). To examine whether inhaling corticosteroids reduce exhaled CO concentration in a given asthmatic patient, 12 patients with symptomatic asthma who were being treated by inhaled β2-agonists alone underwent measurements of exhaled CO concentration before and 4 wk after the initiation of inhal...
TL;DR: It is suggested that drinking green tea daily would contribute to maintain plasma catechin levels sufficient to exert antioxidant activity against oxidative modification of lipoproteins in blood circulation systems.
Abstract: Tea catechins, (-)-epigallocatechin-3-gallate (EGCg) and (-)-epigallocatechin (EGC), have been reported to suppress oxidation of plasma low density lipoprotein (LDL) in vitro. If dietary catechins can be efficiently incorporated into human blood plasma, anti-atherosclerotic effects in preventing oxidative modification of LDL would be expected. In this study, a newly developed chemiluminescence detection-high pressure liquid chromatography (CL-HPLC) method for measuring plasma catechins was used and the incorporation of EGCg and EGC into human plasma was investigated. Healthy subjects orally ingested 3, 5, or 7 capsules of green tea extract (corresponding to 225, 375, and 525 mg EGCg and 7.5, 12.5, and 17.5 mg EGC, respectively). The plasma EGCg and EGC concentrations before the administration were all below the detection limit (< 2 pmol/ml), but 90 min after, significantly and dose-dependently increased to 657, 4300, and 4410 pmol EGCg/ml, and 35, 144, and 255 pmol EGC/ml, in the subjects who received 3, 5, and 7 capsules, respectively. Both EGCg and EGC levels detected in plasma corresponded to 0.2-2.0% of the ingested amount. Catechin intake had no effect on the basal level of endogenous antioxidants (alpha-tocopherol, beta-carotene, and lycopene) or of lipids in plasma. These results suggested that drinking green tea daily would contribute to maintain plasma catechin levels sufficient to exert antioxidant activity against oxidative modification of lipoproteins in blood circulation systems.
TL;DR: In this paper, the extinction limits and the lean flammability limit of nonadiabatic stretched premixed methane-air flames are investigated numerically with detailed chemistry and two different Planck mean absorption coefficient models.
Abstract: Extinction limits and the lean flammability limit of non-adiabatic stretched premixed methane-air flames are investigated numerically with detailed chemistry and two different Planck mean absorption coefficient models. Attention is paid to the combined effect of radiative heat loss and stretch at low stretch rate. It is found that for a mixture at an equivalence ratio lower than the standard lean flammability limit, a moderate stretch can strengthen the combustion and allow burning. The flame is extinguished at a high stretch rate due to stretch and is quenched at a low stretch rate due to radiation loss. A O-shaped curve of flame temperature versus stretch rate with two distinct extinction limits, a radiation extinction limit and a stretch extinction limit respectively on the left- and right-hand sides, is obtained. A C-shaped curve showing the flammability limit of the stretched methane-air flame is obtained by plotting these two extinction limits in the mixture strength coordinate. A good agreement is shown on comparing the predicted results with the experimental data. For equivalence ratio larger than a critical value, it is found that the O-shaped temperature curve opens up in the middle of the stable branch, so that the stable branch divides into two stable flame branches; a weak flame branch and a normal flame branch. The weak flame can survive between the radiation extinction limit and the opening point (jump limit) while the normal flame branch can survive from its stretch extinction limit to zero stretch rate. Finally, a G-shaped curve showing both extinction limits and jump limits of stretched methane-air flames is presented. It is found that the critical equivalence ratio for opening up corresponds to the standard flammability limit measured in microgravity. Furthermore, the results show that the flammability limit (inferior limit) of the stretched methane-air flame is lower than the standard flammability limit because flames are strengthened by a moderate stretch at Lewis number less than unity.
TL;DR: It is demonstrated that aromatase is expressed widely in human bone tissue and may play important roles in maintenance of human bone tissues.
Abstract: Peripheral aromatization of androgens exert estrogenic actions in many tissues. Recently in situ production of estrogens by aromatase was detected in human bone and cultured osteoblasts and has been proposed to participate in the maintenance of bone mass. We examined aromatase expression by immunohistochemistry and mRNA in situ hybridization in 16 cases of tibia (female 2 male, 14 female, 62 6 5.2 years old) and quantified the level of aromatase mRNA in 28 cases of rib, femur, and lumbar vertebrae (16 male, 12 female, 58.0 6 11.3 years old) by reverse transcriptase-polymerase chain reaction (RT-PCR) in order to study whether or not and in which cell types aromatase was expressed in human bone tissues. We also studied alternative use of multiple exons 1 of its gene and immunolocalization of type I 17b-hydroxysteroid dehydrogenase (HSD), which converts estrone produced by aromatase to estradiol. Strong aromatase immunoreactivity and mRNA hybridization as well as type I 17b-HSD immunoreactivity were detected in lining cells, osteoblasts, chondrocytes of articular cartilage, and adipocytes adjacent to bone trabeculae in all the cases examined. Amounts of aromatase mRNA varied greatly among the subjects (11.25 6 9.77, 0.61‐42.84 attomol/ng of total RNA). The amount of aromatase expression was not correlated with age or gender of the subjects but positively correlated with the degree of osteroporotic changes evaluated by radiological findings of lumbar vertebrae. Analysis of multiple exons 1 revealed that 1b or fibroblast type was predominantly (23/26) utilized as a promoter of aromatase gene expression. These results demonstrated that aromatase is expressed widely in human bone tissue and may play important roles in maintenance of human bone tissue. (J Bone Miner Res 1997;12:1416‐1423)
Tohoku University1, Stanford University2, Kent State University3, American University4, California Institute of Technology5, University of Wisconsin-Madison6, University of Massachusetts Amherst7, Princeton University8, University of Michigan9, Smith College10, University of California, Los Angeles11, College of William & Mary12, Syracuse University13, Old Dominion University14, Oregon State University15, University of Bonn16, Temple University17, Northwestern University18, University of Pennsylvania19, University of California, Berkeley20, National Institute of Standards and Technology21
TL;DR: For the kinematic range of $0.014lxl0.7$ and $1l{Q}^{2}l17(\mathrm{GeV}/c{)}^{2] 2, this article reported a precision measurement of the neutron spin structure function using deep inelastic scattering of polarized electrons.
Abstract: We report on a precision measurement of the neutron spin structure function ${g}_{1}^{n}$ using deep inelastic scattering of polarized electrons by polarized ${}^{3}\mathrm{He}$. For the kinematic range $0.014lxl0.7$ and $1l{Q}^{2}l17(\mathrm{GeV}/c{)}^{2}$, we obtain $\ensuremath{\int}{0.014}^{0.7}{g}_{1}^{n}(x)dx\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.036\ifmmode\pm\else\textpm\fi{}0.004(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.005(\mathrm{syst})$ at an average ${Q}^{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}5(\mathrm{GeV}/c{)}^{2}$. We find relatively large negative values for ${g}_{1}^{n}$ at low $x$. The results call into question the usual Regge theory method for extrapolating to $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ to find the full neutron integral $\ensuremath{\int}{1}^{}{g}_{1}^{n}(x)\mathrm{dx}$, needed for testing the quark-parton model and QCD sum rules.
TL;DR: In this paper, the authors show that single-wall nanotubes with mean radii 0.55, 0.65, and 1.0 nm show size-dependent multiple splittings of the optical phonon peak corresponding to the ${E}_{2g}$ mode in graphite.
Abstract: Raman scattering spectra of single-wall nanotubes with mean radii 0.55, 0.65, and 1.0 nm show size-dependent multiple splittings of the optical phonon peak corresponding to the ${E}_{2g}$ mode in graphite. These splittings constitute the first experimental evidence for the unique feature of nanotubes that they exhibit discrete and diameter-dependent dispersions arising from their cylindrical symmetry. The observed dispersion is well explained on the basis of graphite, and shows possibilities of predicting and controlling the basic property of nanotubes in the zone-folding scheme.
TL;DR: Data suggest that dendritic cells respond to some haptens by changing their expression of several co‐stimulatory molecules and their production of cytokines with a resultant change in antigen‐presenting function, and suggest that these chemicals stimulate DC by different mechanisms.
Abstract: After application of haptens to the skin, Langerhans cells (LC), i.e. immature dendritic cells (DC) in the skin, move to secondary lymphoid organs to sensitize naive T cells. During this process, LC become mature DC with augmented expression of various co-stimulatory molecules and MHC class II antigens. In this scenario, however, critical questions remain as to what kind of chemicals can induce this maturation process through what kind of mechanisms. To clarify these questions, we used monocyte-derived CD1a+ DC instead of LC since LC maturated spontaneously in vitro culture. After we confirmed that monocyte-derived DC showed at least phenotypic characteristics and a response to TNF-alpha similar to LC, we added various chemicals, i.e., dinitrochlorobenzene (DNCB), trinitrochlorobenzene (TNCB), NiCl2, ZnCl2, sodium dodecyl sulfate (SDS), or benzalkonium chloride (BC), to a culture of purified monocyte-derived CD1a+ DC. Of these chemicals, only NiCl2 and DNCB significantly increased the surface expression of CD54, CD86, HLA-DR antigen, and interleukin (IL)-1 beta production, while SDS, BC, or ZnCl2 could not augment them, except for weak augmentation of CD86 expression by SDS. The increase in the expression of CD86 induced by NiCl2 or DNCB was most remarkable, being observed in DC from almost all the subjects we examined. TNCB could also induce responses similar to those induced with DNCB, but the number of subjects whose DC responded to it was far less than that of subjects whose DC responded to NiCl2 or DNCB. In spite of the augmented CD86 expression on DC treated with DNCB or NiCl2, these chemicals induced different responses of DC in their expression of CD54 and HLA-DR and the production of IL-6 and tumor necrosis factor (TNF)-alpha. In addition, the up-regulation of CD86 expression on DC treated with DNCB was significantly suppressed by either anti-IL-1 beta or anti-TNF-alpha antibody, while that by NiCl2 was relatively insensitive to these antibody treatments. Finally, the protein kinase C inhibitor, H7, but not staurosporine, could suppress the augmentation of CD86 expression on DC induced either by NiCl2 or by DNCB. These data suggest that DC respond to some haptens by changing their expression of several co-stimulatory molecules and their production of cytokines with a resultant change in antigen-presenting function. They also suggest that these chemicals stimulate DC by different mechanisms. By these responses, DC may modulate the final immune response to chemicals.