RESUMO
The dynamic behaviour of atomic-size disarrangements of atoms-point defects (self-interstitial atoms (SIAs) and vacancies)-often governs the macroscopic properties of crystalline materials. However, the dynamics of SIAs have not been fully uncovered because of their rapid migration. Using a combination of high-voltage transmission electron microscopy and exhaustive kinetic Monte Carlo simulations, we determine the dynamics of the rapidly migrating SIAs from the formation process of the nanoscale SIA clusters in tungsten as a typical body-centred cubic (BCC) structure metal under the constant-rate production of both types of point defects with high-energy electron irradiation, which must reflect the dynamics of individual SIAs. We reveal that the migration dimension of SIAs is not three-dimensional (3D) but one-dimensional (1D). This result overturns the long-standing and well-accepted view of SIAs in BCC metals and supports recent results obtained by ab-initio simulations. The SIA dynamics clarified here will be one of the key factors to accurately predict the lifetimes of nuclear fission and fusion materials.
RESUMO
The autosomal dominant cerebellar ataxias (ADCAs) comprise a genetically and clinically heterogenous group of neurodegenerative disorders. Very recently, a C-to-T single nucleotide substitution in the puratrophin-1 gene was found to be strongly associated with a form of ADCA linked to chromosome 16q22.1 (16q-linked ADCA; OMIM 600223). We found the C-to-T substitution in the puratrophin-1 gene in 20 patients with ataxia (16 heterozygotes and four homozygotes) and four asymptomatic carriers in 9 of 24 families with an unknown type of ADCA. We also found two cases with 16q-linked ADCA among 43 sporadic patients with late-onset cortical cerebellar atrophy (LCCA). The mean age at onset in the 22 patients was 61.8 years, and that of homozygous patients was lower than that of heterozygous ones in one family. Neurological examination revealed that the majority of our patients showed exaggerated deep tendon reflexes in addition to the cardinal symptom of cerebellar ataxia (100%), and 37.5% of them had sensorineural hearing impairment, whereas sensory axonal neuropathy was absent. The frequency of 16q-linked ADCA was about 1/10 of our series of 110 ADCA families, making it the third most frequent ADCA in Japan.
Assuntos
Ataxia Cerebelar/genética , Cromossomos Humanos Par 16 , Genes Dominantes , Fatores de Troca do Nucleotídeo Guanina/genética , Espectrina/genética , Idade de Início , Idoso , Idoso de 80 Anos ou mais , Ataxia Cerebelar/patologia , Análise Mutacional de DNA/métodos , Saúde da Família , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único/genética , RNA Mensageiro/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodosAssuntos
Isquemia Encefálica/complicações , Lateralidade Funcional/fisiologia , Doença de Parkinson Secundária/etiologia , Substância Negra/patologia , Idoso , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Substância Negra/diagnóstico por imagem , Tomografia Computadorizada de Emissão , Tomografia Computadorizada por Raios X/métodosRESUMO
A novel series of pivaloyloxy benzene derivatives has been identified as potent and selective human neutrophil elastase (HNE) inhibitors. Convergent syntheses were developed in order to identify the inhibitors which are intravenously effective in an animal model. A compound of particular interest is the sulfonanilide-containing analogues. Structure-activity relationships are discussed. Structural requirements for metabolic stabilization are also discussed.