RESUMO
We present measurements of spin relaxation times (T1, T1ρ, T2) on very shallow (â²5 nm) nitrogen-vacancy centers in high-purity diamond single crystals. We find a reduction of spin relaxation times up to 30 times compared to bulk values, indicating the presence of ubiquitous magnetic impurities associated with the surface. Our measurements yield a density of 0.01-0.1µB/nm2 and a characteristic correlation time of 0.28(3) ns of surface states, with little variation between samples and chemical surface terminations. A low temperature measurement further confirms that fluctuations are thermally activated. The data support the atomistic picture where impurities are associated with the top carbon layers, and not with terminating surface atoms or adsorbate molecules. The low spin density implies that the presence of a single surface impurity is sufficient to cause spin relaxation of a shallow nitrogen-vacancy center.
RESUMO
We report successful introduction of negatively charged nitrogen-vacancy (NV(-)) centers in a 5 nm thin, isotopically enriched ([(12)C] = 99.99%) diamond layer by CVD. The present method allows for the formation of NV(-) in such a thin layer even when the surface is terminated by hydrogen atoms. NV(-) centers are found to have spin coherence times of between T2 ~ 10-100 µs at room temperature. Changing the surface termination to oxygen or fluorine leads to a slight increase in the NV(-) density, but not to any significant change in T2. The minimum detectable magnetic field estimated by this T2 is 3 nT after 100 s of averaging, which would be sufficient for the detection of nuclear magnetic fields exerted by a single proton. We demonstrate the suitability for nanoscale NMR by measuring the fluctuating field from ~10(4) proton nuclei placed on top of the 5 nm diamond film.
RESUMO
We have succeeded in purifying to homogeneity a very labile NADP+-linked isocitrate dehydrogenase (isocitrate: NADP+ oxidoreductase (decarboxylating), EC 1.1.1.42) from a strain of alkalophilic Bacillus, by a simple method, with an overall yield over 76% of the original activity. The molecular weight on Sephadex G-200 was around 90,000; and that by electrophoresis on SDS-polyacrylamide gels was about 44,000. The sedimentation coefficient (s020,w) and isoelectric point of the enzyme were determined to be 3.22 S and pH 4.7, respectively. The enzyme required Mn2+ for the reaction and for stability. The optimum pH for the reaction was in the range 7.8-8.4 at 30 degrees C; the optimum temperature at pH 8.0 was 75 degrees C; the activation energy of the reaction was 6.2 kcal/mol. The Km values for threo-Ds-isocitrate, DL-isocitrate, and NADP+ were 5.4 microM, 9.9 microM, and 7.3 microM, respectively. This enzyme was inhibited by NADPH, glyceraldehyde 3-phosphate, 3-phosphoglycerate, phosphoenol pyruvate, cis-aconitate, alpha-ketoglutarate, and oxaloacetate. In addition, it was subject to a concerted inhibition by a combination of glyoxylate and oxaloacetate, and also to a cumulative inhibition by nucleoside triphosphates.
Assuntos
Bacillus/enzimologia , Isocitrato Desidrogenase/isolamento & purificação , Fracionamento Celular , Cromatografia em Gel , Temperatura Alta , Concentração de Íons de Hidrogênio , Isocitrato Desidrogenase/antagonistas & inibidores , Isocitrato Desidrogenase/metabolismo , Manganês/metabolismo , Peso Molecular , Nucleotídeos de Purina/farmacologia , Especificidade por Substrato , Triazinas , UltracentrifugaçãoRESUMO
BACKGROUND: Few quantitative studies have been conducted on the relationship between society and its languages. Individuals with autistic spectrum disorder (ASD) are known to experience social hardships, and a wide range of clinical information about their quality of life has been provided through numerous narrative analyses. However, the narratives of ASD patients have thus far been examined mainly through qualitative approaches. OBJECTIVES: In this study, we analyzed adults with ASD to quantitatively examine the relationship between language abilities and ASD severity scores. METHODS: We generated phonetic transcriptions of speeches by 16 ASD adults at an ASD workshop, and divided the participants into 2 groups according to their Social Responsiveness Scale(TM), 2nd Edition (SRS(TM)-2) scores (where higher scores represent more severe ASD): Group A comprised high-scoring ASD adults (SRS(TM)-2 score: ≥â 76) and Group B comprised low- and intermediate-scoring ASD adults (SRS(TM)-2 score: <â 76). Using natural language processing (NLP)-based analytical methods, the narratives were converted into numerical data according to four language ability indicators, and the relationships between the language ability scores and ASD severity scores were compared. RESULTS AND DISCUSSION: Group A showed a marginally negative correlation with the level of Japanese word difficulty (p <â .10), while the "social cognition" subscale of the SRS(TM)-2 score showed a significantly negative correlation (p <â .05) with word difficulty. When comparing only male participants, Group A demonstrated a significantly lower correlation with word difficulty level than Group B (p <â .10). CONCLUSION: Social communication was found to be strongly associated with the level of word difficulty in speech. The clinical applications of these findings may be available in the near future, and there is a need for further detailed study on language metrics designed for ASD adults.
Assuntos
Transtorno do Espectro Autista/diagnóstico , Transtorno do Espectro Autista/fisiopatologia , Cognição , Idioma , Comportamento Social , Vocabulário , Adulto , Idoso , Feminino , Humanos , Japão , Masculino , Pessoa de Meia-IdadeRESUMO
A neutron bang time and burn history monitor in inertial confinement fusion with fast ignition are necessary for plasma diagnostics. In the FIREX project, however, no detector attained those capabilities because high-intensity X-rays accompanied fast electrons used for plasma heating. To solve this problem, single-crystal CVD diamond was grown and fabricated into a radiation detector. The detector, which had excellent charge transportation property, was tested to obtain a response function for intense X-rays. The applicability for neutron bang time and burn history monitor was verified experimentally. Charge collection efficiency of 99.5% ± 0.8% and 97.1% ± 1.4% for holes and electrons were obtained using 5.486 MeV alpha particles. The drift velocity at electric field which saturates charge collection efficiency was 1.1 ± 0.4 × 10(7) cm/s and 1.0 ± 0.3 × 10(7) cm/s for holes and electrons. Fast response of several ns pulse width for intense X-ray was obtained at the GEKKO XII experiment, which is sufficiently fast for ToF measurements to obtain a neutron signal separately from X-rays. Based on these results, we confirmed that the single-crystal CVD diamond detector obtained neutron signal with good S/N under ion temperature 0.5-1 keV and neutron yield of more than 10(9) neutrons/shot.
RESUMO
An enzyme extract from Cellulase-Onozuka, a commercial product of Trichoderma viride, was fractionated by Amberlite CG-50 column chromatography into three cellulase [EC 3.2.1.4] groups, peaks I to III. A noval enzyme, which has both beta-glucosidase [EC 3.2.1.21] and exo-carboxymethyl-cellulase (exo-CMCase) properties was obtained from peak III by extensive purification throuh consecutive column chromatography. The enzyme was homogeneous on ultracentrifugation, SDS-gel and cellulose acetate film electrophoreses and molecular sieve chromatography on Bio-Gel P-150. The molecular weight of this enzyme was estimated to be 53,000. The enzyme appeared to release cellobiose residues one by one from the nonreducing end of higher cellooligosaccharides and CM-cellulose (CMC), but to release glucosyl residues from reduced cellotriose and beta-cellobioside, resembling a beta-glucosidase in this respect. Furthermore, this exo-CMCase also attacked xylan exo-wise to produce xylobiose moleculaes one by one, but it scarcely attacked insoluble cellulose, except for a cellodextrin apparently rich in amorphous structure.
Assuntos
Celulase/metabolismo , Glicosídeo Hidrolases/metabolismo , Fungos Mitospóricos/enzimologia , Trichoderma/enzimologia , Animais , Carboidratos/análise , Celulase/isolamento & purificação , Estabilidade de Medicamentos , Glucosidases/isolamento & purificação , Glucosidases/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Peso Molecular , TemperaturaRESUMO
Mutarotation of products from p-nitrophenyl beta-D-cellobioside and cellopentaitol by two different types of exo-cellulases from Trichoderma viride was investigated. It was found that an exo-cellulase of glucosidase type produced from the former substrate D-glucose which was mutarotated in a downward direction, while another exo-cellulase of Avicelase type produced from the latter substrate cellobiose which was mutarotated in an upward direction.
Assuntos
Celulose , Glucosidases , Fungos Mitospóricos/enzimologia , Oligossacarídeos , Trichoderma/enzimologia , beta-Glucosidase , Animais , Celulose/metabolismo , Glucosidases/metabolismo , Cinética , Conformação Molecular , Rotação Ocular , beta-Glucosidase/metabolismoRESUMO
The Serratia marcescens serine protease (SSP; 66 kDa) is synthesized as a precursor (preproSSP; 112 kDa) composed of the NH2-terminal signal peptide of 27 amino acids, the mature protease part and a large COOH-terminal domain. When the SSP gene is expressed in Escherichia coli under the control of the tac promoter, the mature enzyme is excreted into the medium through the outer membrane, whereas preproSSP and two proteins, C-1 (40 kDa) and C-2 (38 kDa), processed from the COOH-terminal domain, are accumulated in the membrane fraction. Although treatment of the intact cells with trypsin caused slight truncation of C-1 and C-2, the main parts of C-1 and C-2, both of which are detected in the outer membrane, were resistant to trypsin, even after the cells had been osmotically shocked. Consistent with this, a high content of beta-sheet structure in C-2 was suggested by marked heat-modifiability, as determined by their electrophoretic mobilities on SDS-polyacrylamide gel. These findings suggest rigid integration of C-1 and C-2 in the outer membrane. Upon induction of the tac promoter, rapid excretion of SSP into the medium was first accompanied by the accumulation of C-1 in the outer membrane, which was followed by conversion of C-1 to C-2. PreproSSP was not detected during the accumulation of SSP in the medium, but it was gradually accumulated after the accumulation of SSP had reached a plateau. In addition, preproSSP still containing the intact NH2-terminal signal peptide was completely digested with trypsin when added to osmotically shocked cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Precursores Enzimáticos/metabolismo , Escherichia coli/enzimologia , Serina Endopeptidases/metabolismo , Serratia marcescens/enzimologia , Sequência de Aminoácidos , Western Blotting , Eletroforese em Gel de Poliacrilamida , Precursores Enzimáticos/biossíntese , Precursores Enzimáticos/química , Precursores Enzimáticos/genética , Escherichia coli/citologia , Temperatura Alta , Dados de Sequência Molecular , Peso Molecular , Plasmídeos , Regiões Promotoras Genéticas , Estrutura Secundária de Proteína , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Serina Endopeptidases/biossíntese , Serina Endopeptidases/química , Serina Endopeptidases/genéticaRESUMO
The Serratia marcescens serine protease gene encoding a 1,045-amino-acid precursor protein of 112 kDa directs excretion of the mature protease of ca. 58 kDa through the outer membrane of Escherichia coli. A typical signal peptide of 27 amino acids and a large COOH-terminal domain of the precursor are both functionally essential for the excretion of the mature protease into the medium. Sequence analysis of the fragment peptides of the mature protease as well as site-directed mutagenesis indicated that the COOH-terminus of the mature enzyme was Asp645. By using the polyclonal antibody against the 112-kDa precursor protein, not only the intact precursor but also two proteins, C-1 (40 kDa) and C-2 (38 kDa), corresponding to the processed COOH-terminal domains were detected in the insoluble fraction of E. coli cells. Further fractionation by sucrose density gradient centrifugation showed that C-1 and C-2 were localized in the outer membrane. The NH2-terminal residues of C-1 and C-2 were determined to be Ala702 and Phe717, respectively. All these data suggest that the precursor is cleaved at three positions, between Asp645-Ser646, Glu701-Ala702, and Gly716-Phe717, probably by the self-processing activity in the normal excretion pathway through the outer membrane.
Assuntos
Precursores Enzimáticos/metabolismo , Serina Endopeptidases/metabolismo , Serratia marcescens/enzimologia , Sequência de Aminoácidos , Sequência de Bases , Membrana Celular/enzimologia , DNA Bacteriano/genética , Precursores Enzimáticos/química , Precursores Enzimáticos/genética , Escherichia coli/enzimologia , Escherichia coli/genética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Processamento de Proteína Pós-Traducional , Serina Endopeptidases/química , Serina Endopeptidases/genética , Serratia marcescens/genéticaRESUMO
Confinement of charge carriers in semiconductors by quantum wells is usually accomplished with layers that vary in elemental composition, such as aluminum gallium arsenide and gallium arsenide. We fabricated diamond superlattices by creating multilayer structures of isotopically pure carbon isotopes carbon-12 (12C) and carbon-13 (13C), which confine electrons by a difference in band-gap energy of 17 millielectron volts. Cathodoluminescence experiments performed at 80 kelvin showed that excitonic recombination in the higher-energy band of 13C vanishes in favor of increased recombination in the lower-energy 12C material. Carrier confinement was achieved in diamond superlattices made up of both thinner (30 nanometers) and thicker (up to 350 nanometers) layers.
RESUMO
Fundamental problems of incoherent optical heterodyne detection are analyzed. Output of the heterodyne detection depends on the spatial and temporal coherences of incoming incoherent signal light on the photodetector surface. The directivity of optical heterodyne detection is concluded to be the same as with that of direct detection in an ideal case in which the image of the object is well focused on the photodetector surface. This incoherent heterodyne detection is applied to air pollution monitoring. In the laboratory, the absorption spectra due to NH(3), Freon, and SF(6) are measured using an incoherent light source, and the concentrations of each gas were determined by using the least-squares method.
RESUMO
A gene for alkaline cellulase from the alkalophilic Bacillus sp. KSM-635 was cloned into the HindIII site of pBR322 and expressed in Escherichia coli HB101. Although the recombinant plasmid contained two HindIII inserts of 2.6 kb and 4.0 kb, the inserts were found to be contiguous in the Bacillus genome by hybridization analysis. Nucleotide sequences of a 2.4 kb region which was indispensable for the production of cellulase, and the flanking, 1.1 kb region, were determined. There was an open reading frame (ORF) of 2823 bp in the 3498 bp sequence determined, which encoded 941 amino acid residues. Two putative ribosome-binding sites and a sigma 43-type, promoter-like sequence were found upstream from an initiation codon in the ORF. The deduced amino-terminal sequence resembles the signal peptide of extracellular proteins. A region of amino acids, 249 to 568, of the deduced amino acid sequence of the cellulase from this organism is homologous with those of alkaline and neutral enzymes of other micro-organisms, but nine amino acid residues were found to be conserved only in the alkaline enzymes.
Assuntos
Bacillus/genética , Celulase/genética , Sequência de Aminoácidos , Bacillus/enzimologia , Sequência de Bases , Sítios de Ligação , Celulase/metabolismo , Clonagem Molecular , Escherichia coli/genética , Genes Bacterianos , Concentração de Íons de Hidrogênio , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Fases de Leitura Aberta , Regiões Promotoras Genéticas , Mapeamento por Restrição , Homologia de Sequência do Ácido NucleicoRESUMO
Production of polyvinly alcohol (PVA) oxidase by Pseudomonas sp. strain VM15C, a PVA degrader of a symbiotic PVA-utilizing mixed culture, was examined in various cultures. Despite the absence of PVA in the culture in nutrient broth, VM15C showed approximately the same productivity of PVA oxidase activity as that in the culture with PVA as the sole carbon source, whereas the productivity in the culture with glucose was lower than that of either the nutrient broth or the PVA culture. PVA oxidase activity produced in the nutrient broth culture was predominantly present in the cells, and most of the activity appeared to be in the cytoplasm. In contrast, in the culture with PVA as the sole carbon source, the activity was present in the culture fluid in a larger ratio than in the nutrient broth culture. Thus, production of PVA oxidase activity by this strain was constitutive and repressible, although localization of the produced activity was changed by growth conditions.
RESUMO
A 70-year-old woman was admitted to our hospital for evaluation of a nodular shadow and an apparent cavity in the right middle lung field. Transbronchial biopsy and percutaneous needle biopsy had failed to result in a diagnosis. Serial chest X-ray films revealed slight regression of the nodule without therapy. Pulmonary dirofilariasis was diagnosed after open-lung biopsy and Ouchterlony's double diffusion test. Cavity formation and spontaneous regression are rare in pulmonary dirofilariasis.