Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 242
Filtrar
1.
Nat Commun ; 8(1): 2097, 2017 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-29235469

RESUMO

Dirac and Weyl semimetals with linearly crossing bands are the focus of much recent interest in condensed matter physics. Although they host fascinating phenomena, their physics can be understood in terms of weakly interacting electrons. In contrast, more than 40 years ago, Abrikosov pointed out that quadratic band touchings are generically strongly interacting. We have performed terahertz spectroscopy on the films of the conducting pyrochlore Pr2Ir2O7, which has been shown to host a quadratic band touching. A dielectric constant as large as [Formula: see text] is observed at low temperatures. In such systems, the dielectric constant is a measure of the relative scale of interactions, which are therefore in our material almost two orders of magnitude larger than the kinetic energy. Despite this, the scattering rate exhibits a T 2 dependence, which shows that for finite doping a Fermi liquid state survives-however, with a scattering rate close to the maximal value allowed.

2.
Phys Rev Lett ; 119(22): 222501, 2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-29286806

RESUMO

Fission-fragment mass distributions were measured for ^{237-240}U, ^{239-242}Np, and ^{241-244}Pu populated in the excitation-energy range from 10 to 60 MeV by multinucleon transfer channels in the reaction ^{18}O+^{238}U at the Japan Atomic Energy Agency tandem facility. Among them, the data for ^{240}U and ^{240,241,242}Np were observed for the first time. It was found that the mass distributions for all the studied nuclides maintain a double-humped shape up to the highest measured energy in contrast to expectations of predominantly symmetric fission due to the washing out of nuclear shell effects. From a comparison with the dynamical calculation based on the fluctuation-dissipation model, this behavior of the mass distributions was unambiguously attributed to the effect of multichance fission.

3.
Chem Commun (Camb) ; 51(2): 413-6, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25406914

RESUMO

A hybrid comprising an autophagy-inducing peptide (AIP) and a cell-penetrating peptide (CPP) connected via heterodimeric leucine zippers was generated and delivered into cells. The hybrid successfully induced autophagy without significant cell death, while the same AIP directly connected to a CPP caused both autophagy and significant cell death.


Assuntos
Autofagia/efeitos dos fármacos , Peptídeos Penetradores de Células/química , Zíper de Leucina , Peptídeos/química , Peptídeos/farmacologia , Sequência de Aminoácidos , Células HeLa , Humanos , Dados de Sequência Molecular , Peptídeos/administração & dosagem
4.
J Phys Condens Matter ; 26(6): 064206, 2014 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-24469025

RESUMO

To understand the hard magnetism of L10-type ordered FeNi alloy, we extracted the L10-FeNi phase from a natural meteorite, and evaluated its fundamental solid-state properties: sample composition, magnetic hysteresis, crystal structure and electronic structure. We executed multidirectional analyses using scanning electron microscopy with an electron probe micro-analyzer (SEM-EPMA), a superconducting quantum interference device (SQUID), x-ray diffraction (XRD) and magnetic circular dichroism (MCD). As a result, we found that the composition was Fe: 50.47 ± 1.98 at.%, Ni: 49.60 ± 1.49 at.%, and an obvious superlattice peak is confirmed. The estimated degree of order was 0.608, with lattice constants a = b = 3.582 Å and c = 3.607 Å. The obtained coercivity was more than 500 Oe. MCD analysis using the K absorption edge suggests that the magnetic anisotropy could originate from the orbital magnetic moment of 3d electrons in Fe; this result is consistent with that in a previous report obtained with synthetic L10-FeNi.


Assuntos
Ligas/química , Elétrons , Ferro/química , Fenômenos Magnéticos , Meteoroides , Níquel/química
5.
Water Sci Technol ; 63(10): 2164-82, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21977635

RESUMO

This study aims at synthesizing experiences in the practical application of ASM type models. The information is made easily accessible to model users by creating a database of modelling projects. This database includes answers to a questionnaire that was sent out to model users in 2008 to provide inputs for a Scientific and Technical Report of the IWA Task Group on Good Modelling Practice - Guidelines for use of activated sludge models, and a literature review on published modelling projects. The database is analysed to determine which biokinetic model parameters are usually changed by modellers, in which ranges, and what values are typically used for seven selected activated sludge models. These results should help model users in the calibration step, by providing typical parameter values as a starting point and ranges as a guide. However, the proposed values should be used with great care since they are the result of averaging practical experience and not taking into account specific parameter correlations.


Assuntos
Bases de Dados como Assunto , Modelos Teóricos , Esgotos/química , Esgotos/microbiologia
6.
Phys Rev Lett ; 106(4): 047602, 2011 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-21405362

RESUMO

We study the surface and bulk electronic structure of the room-temperature ferromagnet Co∶TiO(2) anatase films using soft- and hard-x-ray photoemission spectroscopy with probe sensitivities of ∼1 and ∼10 nm, respectively. We obtain direct evidence of metallic Ti(3+) states in the bulk, which get suppressed to give a surface semiconductor, thus indicating the difference in electronic structure between surface and bulk. X-ray absorption and resonant photoemission spectroscopy reveal Ti(3+) electrons at the Fermi level (E(F)) and high-spin Co(2+) electrons occurring away from E(F). The results show the importance of the charge neutrality condition: Co(2+)+V(O)(2-)+2Ti(4+)↔Co(2+)+2Ti(3+) (V(O) is oxygen vacancy), which gives rise to the elusive Ti 3d carriers mediating ferromagnetism via the Co 3d-O 2p-Ti 3d exchange interaction pathway of the occupied orbitals.

7.
AJNR Am J Neuroradiol ; 31(8): 1498-503, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20448017

RESUMO

BACKGROUND AND PURPOSE: Although MBs, ICH, and LI are secondary to cerebral microangiopathy, it remains unclear whether the location of subsequent ICH/LI corresponds to the previous location of MBs. We performed this study to clarify the positional relationship between recurrent ICH/LI and previously detected MBs. MATERIALS AND METHODS: We evaluated patients with recurrent ICH/LI who had MBs, as shown on prior T2*-weighted MR imaging. We assessed retrospectively whether the location of recurrent ICH/LI corresponded to that of the prior MB. Patients with ICH were divided into the deep ICH group and the lobar ICH group, and the positional relationship between hematoma and previously detected MBs was evaluated. RESULTS: A total of 55 patients, including 34 with recurrent ICH and 21 with recurrent LI were evaluated. Although the location of the LI corresponded to prior MBs in only 1 patient (4.8%), the location of ICH corresponded to prior locations of MBs in 21 patients (61.8%) (OR, 32.3; 95% CI, 3.86-270.3; P < .001). Among the patients with ICH, the correspondence ratio was higher in the deep ICH group (19 of 24 patients, 79.2%) than in the lobar ICH group (2 of 10 patients, 20%) (OR, 15.2; 95% CI, 2.42-95.3; P < .002). CONCLUSIONS: The close positional association between recurrent ICH and prior MBs suggests that MBs represent hemorrhage-prone microangiopathy. In addition, different correspondence ratios between the deep ICH group and the lobar ICH group may be attributable to their different pathogenesis.


Assuntos
Infarto Encefálico/patologia , Hemorragia Cerebral/patologia , Circulação Cerebrovascular , Imageamento por Ressonância Magnética , Microcirculação , Idoso , Idoso de 80 Anos ou mais , Feminino , Hematoma/patologia , Humanos , Masculino , Microvasos/patologia , Pessoa de Meia-Idade , Putamen/irrigação sanguínea , Putamen/patologia , Recidiva , Estudos Retrospectivos , Tálamo/irrigação sanguínea , Tálamo/patologia
9.
Water Sci Technol ; 60(8): 1943-51, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19844041

RESUMO

The Good Modelling Practice Task Group (GMP-TG) of the International Water Association (IWA) is developing guidelines for the use of Activated Sludge Models (ASM). As part of this work the group created and sent out a questionnaire to current and potential activated sludge model users in 2007. The objectives of the questionnaire were (i) to better define the profile of ASM users, (ii) to identify the tools and procedures that are actually used and (iii) to highlight the main limitations while building and using ASM-type models. Ninety-six answers were received from all over the world, from several types of organisation. The results were analysed to identify the modellers' perceptions of models depending on their profile. The results also highlighted the main topics of interest for improving modelling procedures which are standardisation of the available modelling guidelines and better experience and knowledge transfer.


Assuntos
Coleta de Dados , Internacionalidade , Modelos Teóricos , Esgotos/química , Geografia , Organizações , Fatores de Tempo
10.
Appl Radiat Isot ; 67(4): 539-43, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19136264

RESUMO

In order to prepare sources of short-lived actinides for alpha-particle spectrometry, a coprecipitation method with Sm hydroxide was developed. The preparation procedure can be completed within 5 min with a high chemical yield of over 90%. It was found that the uniformity of the produced sources was sufficient to provide a high resolution of better than 20 keV. Under this method, we successfully measured the alpha-particle spectrum of short-lived Cf isotopes produced in the (238)U((12)C, xn) reaction.

11.
Appl Radiat Isot ; 67(2): 243-7, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19059787

RESUMO

The excitation function of the (nat)Er(p,xn)(165)Tm reaction resulting in production of (165)Er was measured up to 70 MeV by activation of stacked foils practically for the first time. The theoretical interpretation is based on the results of the ALICE-IPPE and EMPIRE-II codes. From the measured experimental cross section data integral production yield was calculated and compared with experimental integral yield data reported in the literature. Different production routes of the therapeutic radioisotope (165)Er were compared.


Assuntos
Érbio/química , Prótons , Radioisótopos/química , Radioquímica/métodos , Compostos Radiofarmacêuticos/síntese química
12.
AJNR Am J Neuroradiol ; 29(8): 1483-6, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18499791

RESUMO

BACKGROUND AND PURPOSE: Although accumulating evidence suggests the presence of microbleeds as a risk factor for intracerebral hemorrhage (ICH), little is known about its significance in anticoagulated patients. The aim of this study was to determine whether the presence of microbleeds is associated with recurrent hemorrhagic stroke in patients who had received warfarin following atrial fibrillation-associated cardioembolic infarction. MATERIALS AND METHODS: A total of 87 consecutive patients with acute recurrent stroke, including 15 patients with ICH and 72 patients with cerebral infarction, were enrolled in this study. International normalized ratios (INRs), vascular risk factors, and imaging characteristics, including microbleeds on T2*-weighted MR images and white matter hyperintensity (WMH) on T2-weighted MR images, were compared in the 2 groups. RESULTS: Microbleeds were noted more frequently in patients with ICH than in patients with cerebral infarction (86.7% versus 38.9%, P = .0007). The number of microbleeds was larger in patients with ICH than in patients with cerebral infarction (mean, 8.4 versus 2.1; P = .0001). INR was higher in patients with ICH than in patients with cerebral infarction (mean, 2.2 versus 1.4; P < .0001). The frequency of hypertension was higher in patients with ICH than in patients with cerebral infarction (86.7% versus 45.8%, P = .0039). Multivariate analysis revealed that the presence of cerebral microbleeds (odds ratio, 7.383; 95% confidence interval, 1.052-51.830) was associated with ICH independent of increased INR and hypertension. CONCLUSION: The presence of cerebral microbleeds may be an independent risk factor for warfarin-related ICH, but more study is needed because of strong confounding associations with elevated INR and hypertension.


Assuntos
Isquemia Encefálica/diagnóstico , Isquemia Encefálica/tratamento farmacológico , Hemorragia Cerebral/induzido quimicamente , Hemorragia Cerebral/diagnóstico , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/tratamento farmacológico , Varfarina/efeitos adversos , Varfarina/uso terapêutico , Idoso , Anticoagulantes/administração & dosagem , Anticoagulantes/efeitos adversos , Feminino , Humanos , Masculino , Recidiva , Estatística como Assunto , Resultado do Tratamento
13.
Neurosci Lett ; 435(3): 194-7, 2008 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-18384956

RESUMO

Chromosome 1p13 is linked with schizophrenia in Japanese families, and one of the candidate genes in this region is the netrin G1 (NTNG1) gene at 1p13.3. Associations of 56 tag single-nucleotide polymorphisms (SNPs) with schizophrenia were explored by transmission disequilibrium analysis in 160 Japanese trios and by case-control analysis in 2,174 Japanese cases and 2,054 Japanese controls. An association between SNP rs628117 and schizophrenia was identified by case-control comparison (nominal allelic p=0.0009; corrected p=0.006). The associated polymorphism is located in intron 9 and in the haplotype block encompassing the alternatively spliced exons of the gene. Allelic association of a different SNP in the same haplotype block in Japanese families was previously reported. These findings support that the NTNG1 gene is associated with schizophrenia in the Japanese.


Assuntos
Cromossomos Humanos Par 1/genética , Éxons , Predisposição Genética para Doença , Glicoproteínas/genética , Proteínas do Tecido Nervoso/genética , Polimorfismo de Nucleotídeo Único , Esquizofrenia/genética , Adulto , Estudos de Casos e Controles , Distribuição de Qui-Quadrado , Feminino , Proteínas Ligadas por GPI , Frequência do Gene , Haplótipos , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Netrinas , Splicing de RNA
14.
Phys Rev Lett ; 98(25): 252501, 2007 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-17678017

RESUMO

The electron-capture (EC) decay rate of (7)Be in C(60) at the temperature of liquid helium (T=5 K) was measured and compared with the rate in Be metal at T=293 K. We found that the half-life of (7)Be in endohedral C(60) ((7)Be@C(60)) at a temperature close to T=5 K is 52.47+/-0.04 d, a value that is 0.34% faster than that at T=293 K. In this environment, the half-life of (7)Be is nearly 1.5% faster than that inside Be metal at room temperature (T=293 K). We then interpreted our observations in terms of calculations of the electron density at the (7)Be nucleus position inside the C(60); further, we estimate theoretically the temperature dependence (at T=0 K and 293 K) of the electron density at the Be nucleus position in the stable center inside C(60). The theoretical estimates were almost in agreement with the experimental observations.

15.
Appl Radiat Isot ; 65(1): 32-5, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16908177

RESUMO

A technique for preparing nuclear reaction targets of various thicknesses was developed by using common filtration technique of hydroxide precipitates with a porous Al(2)O(3) membrane filter. Uniformity was found to be within a few % in each thickness. Durability for beam irradiation was also confirmed. The preparation procedure is convenient and the method is appropriate for several target materials, including not only precious materials but also radioactive materials with low contamination.


Assuntos
Óxido de Alumínio/química , Óxido de Alumínio/efeitos da radiação , Precipitação Fracionada , Íons Pesados , Física Nuclear/métodos , Ultrafiltração/métodos , Teste de Materiais
16.
Lett Appl Microbiol ; 40(2): 111-6, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15644109

RESUMO

AIMS: A novel xylanolytic multienzyme complex of the aerobic thermophilic fungus Chaetomium sp. nov. MS-017 was produced on palm oil mill fibre (POMF) and partially characterized. METHODS AND RESULTS: The assay of the extracellular enzymes of Chaetomium sp. nov. MS-017 on POMF in solid-state fermentation revealed cellulolytic, pectinolytic and extremely high xylanolytic activities. The protein was purified by Sephadex G-200 column chromatography. The SDS-PAGE demonstrated that the purified protein is a complex with at least five xylanolytic, four cellulolytic and eight pectinolytic components. The characterization of the complex at various temperatures showed that the reactivity and stability of the complex are not lost up to 60 degrees C. In addition, the complex was very stable in a wide range of pH (3-9) and at high concentrations (10 mm) of cations and EDTA. The major products of xylan hydrolysis by the purified complex were determined to be xylobiose and xylotriose by thin-layer chromatography. CONCLUSION: Chaetomium sp. nov. MS-017 preferentially produces a xylanolytic multienzyme complex on POMF in solid-state fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on the xylanolytic multienzyme complex produced by an aerobic thermophilic fungus.


Assuntos
Chaetomium/enzimologia , Chaetomium/crescimento & desenvolvimento , Temperatura Alta , Complexos Multienzimáticos/biossíntese , Óleos de Plantas/metabolismo , Aerobiose , Meios de Cultura , Estabilidade Enzimática , Fermentação , Microbiologia Industrial/métodos , Resíduos Industriais , Óleo de Palmeira , Xilanos/metabolismo
17.
Lett Appl Microbiol ; 39(6): 533-7, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15548307

RESUMO

AIMS: A metabolic pathway for L-2,3-butanediol (BD) as the main product has not yet been found. To rectify this situation, we attempted to produce L-BD from diacetyl (DA) by producing simultaneous expression of diacetyl reductase (DAR) and L-2,3-butanediol dehydrogenase (BDH) using transgenic bacteria, Escherichia coli JM109/pBUD-comb. METHODS AND RESULTS: The meso-BDH of Klebsiella pneumoniae was used for its DAR activity to convert DA to L-acetoin (AC) and the L-BDH of Brevibacterium saccharolyticum was used to reduce L-AC to L-BD. The respective gene coding each enzyme was connected in tandem to the MCS of pFLAG-CTC (pBUD-comb). The divided addition of DA as a source, addition of 2% glucose, and the combination of static and shaking culture was effective for the production. CONCLUSIONS: L-BD (2200 mg l(-1)) was generated from 3000 mg l(-1) added of DA, which corresponded to a 73% conversion rate. Meso-BD as a by-product was mixed by 2% at most. SIGNIFICANCE AND IMPACT OF THE STUDY: An enzyme system for converting DA to L-BD was constructed with a view to using DA-producing bacteria in the future.


Assuntos
Butileno Glicóis/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Acetoína Desidrogenase/genética , Acetoína Desidrogenase/metabolismo , Oxirredutases do Álcool/genética , Oxirredutases do Álcool/metabolismo , Proteínas de Bactérias/genética , Brevibacterium/enzimologia , Brevibacterium/genética , Clonagem Molecular , Diacetil/metabolismo , Fermentação , Vetores Genéticos , Cinética , Klebsiella pneumoniae/enzimologia , Klebsiella pneumoniae/genética , Plasmídeos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Estereoisomerismo
18.
Phys Rev Lett ; 93(11): 112501, 2004 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-15447332

RESUMO

The decay rate of 7Be electron capture was measured in C60 and Be metal with a reference method. The half-life of 7Be endohedral C60 ((7)Be@C(60)) and 7Be in Be metal (Be metal (7Be)) is found to be 52.68+/-0.05 and 53.12+/-0.05 days, respectively. This amounts to a 0.83% difference in electron-capture decay half-life between (7)Be@C(60) and Be metal (7Be). Our result is a reflection of the different electron wave functions for (7)Be@C(60) inside C60 compared to the situation when 7Be is in a Be metal.

19.
Mol Psychiatry ; 9(10): 916-31, 2004 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-15289816

RESUMO

A number of lines of evidence make the gene that encodes the G-protein-coupled CB1/Cnr1 receptor a strong candidate to harbor variants that might contribute to individual differences in human addiction vulnerability. The CB1/Cnr1 receptor is the major brain site at which cannabinoid marijuana constituents are psychoactive as well as the principal brain receptor for endogenous anandamide ligands. It is densely expressed in brain circuits likely to be important for both the reward and mnemonic processes important for addiction. Altered drug effects in CB1/Cnr1 knockout mice and initial association studies also make variants at the CB1/Cnr1 locus candidates for roles in human vulnerabilities to addictions. However, many features of this gene's structure, regulation and variation remain poorly defined. This poor definition has limited the ability of previous association studies to adequately sample variation at this locus. We now report improved definition of the human CB1/Cnr1 locus and its variants. Novel exons 1-3, splice variant and candidate promoter region sequences add to the richness of the CB1/Cnr1 locus. Candidate promoter region sequences confer reporter gene expression in cells that express CB1/Cnr1. Common polymorphisms reveal patterns of linkage disequilibrium in European- and in African-American individuals. A 5' CB1/Cnr1 "TAG" haplotype displays significant allelic frequency differences between substance abusers and controls in European-American, African-American and Japanese samples. Post-mortem brain samples of heterozygous individuals contain less mRNA transcribed from the TAG alleles than from other CB1/Cnr1 haplotypes. CB1/ Cnr1 genomic variation thus appears to play roles in human addiction vulnerability.


Assuntos
Receptor CB1 de Canabinoide/fisiologia , Transtornos Relacionados ao Uso de Substâncias/genética , Negro ou Afro-Americano/genética , Alelos , Animais , Povo Asiático/genética , Baltimore/epidemiologia , Sequência de Bases , Química Encefálica , Células CHO , Cricetinae , Europa (Continente)/etnologia , Éxons/genética , Frequência do Gene , Genes Reporter , Predisposição Genética para Doença , Haplótipos , Humanos , Japão/epidemiologia , Desequilíbrio de Ligação , Dados de Sequência Molecular , Regiões Promotoras Genéticas/genética , Splicing de RNA , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Receptor CB1 de Canabinoide/genética , Transtornos Relacionados ao Uso de Substâncias/etnologia , População Branca/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...