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1.
Philos Trans A Math Phys Eng Sci ; 381(2246): 20220112, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36907214

RESUMO

The large-scale laminar/turbulent spiral patterns that appear in the linearly unstable regime of counter-rotating Taylor-Couette flow are investigated from a statistical perspective by means of direct numerical simulation. Unlike the vast majority of previous numerical studies, we analyse the flow in periodic parallelogram-annular domains, following a coordinate change that aligns one of the parallelogram sides with the spiral pattern. The domain size, shape and spatial resolution have been varied and the results compared with those in a sufficiently large computational orthogonal domain with natural axial and azimuthal periodicity. We find that a minimal parallelogram of the right tilt significantly reduces the computational cost without notably compromising the statistical properties of the supercritical turbulent spiral. Its mean structure, obtained from extremely long time integrations in a co-rotating reference frame using the method of slices, bears remarkable similarity with the turbulent stripes observed in plane Couette flow, the centrifugal instability playing only a secondary role. This article is part of the theme issue 'Taylor-Couette and related flows on the centennial of Taylor's seminal Philosophical transactions paper (Part 2)'.

2.
Nat Commun ; 9(1): 154, 2018 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-29323126

RESUMO

Superconductivity is ubiquitous as evidenced by the observation in many crystals including carrier-doped oxides and diamond. Amorphous solids are no exception. However, it remains to be discovered in quasicrystals, in which atoms are ordered over long distances but not in a periodically repeating arrangement. Here we report electrical resistivity, magnetization, and specific-heat measurements of Al-Zn-Mg quasicrystal, presenting convincing evidence for the emergence of bulk superconductivity at a very low transition temperature of [Formula: see text] K. We also find superconductivity in its approximant crystals, structures that are periodic, but that are very similar to quasicrystals. These observations demonstrate that the effective interaction between electrons remains attractive under variation of the atomic arrangement from periodic to quasiperiodic one. The discovery of the superconducting quasicrystal, in which the fractal geometry interplays with superconductivity, opens the door to a new type of superconductivity, fractal superconductivity.

3.
Philos Trans A Math Phys Eng Sci ; 375(2089)2017 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-28167574

RESUMO

The present work is based on our recent discovery of a new class of exact coherent structures generated near the edge of quite general boundary layer flows. The structures are referred to as free-stream coherent structures and were found using a large Reynolds number asymptotic approach to describe equilibrium solutions of the Navier-Stokes equations. In this paper, first we present results for a new family of free-stream coherent structures existing at relatively large wavenumbers. The new results are consistent with our earlier theoretical result that such structures can generate larger amplitude wall streaks if and only if the local spanwise wavenumber is sufficiently small. In a Blasius boundary layer, the local wavenumber increases in the streamwise direction so the wall streaks can typically exist only over a finite interval. However, here it is shown that they can interact with wall curvature to produce exponentially growing Görtler vortices through the receptivity process by a novel nonparallel mechanism. The theoretical predictions found are confirmed by a hybrid numerical approach. In contrast with previous receptivity investigations, it is shown that the amplitude of the induced vortex is larger than the structures in the free-stream which generate it.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'.

4.
Transplant Proc ; 49(1): 135-138, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28104121

RESUMO

BACKGROUND: Patients with intestinal failure (IF) are candidates for intestinal transplantation (ITx). In Japan, these patients have few opportunities to undergo cadaveric ITx because of low rates of organ donation. The donor criteria and recipient priority for ITx are still unknown. We reviewed our cases of IF to investigate which patients should be prioritized for ITx. METHODS: Patients with IF who were registered as candidates for cadaveric ITx between January 2010 and November 2015 in our institute were included in this retrospective study. Their data were gathered from their charts and analyzed. RESULTS: Five patients were included. Their primary diseases included total colon aganglionosis (n = 1), chronic idiopathic intestinal pseudo-obstruction syndrome (n = 2), superior mesenteric vein embolization (n = 1), and graft loss after ITx (n = 1). Two patients died of liver failure (LF) during the waiting period. The remaining three are now alive and waiting for transplantation. The lengths of the remaining intestine were more than 20 cm in living cases but less than 20 cm in fatal cases. In the fatal cases, they had several episodes of catheter-related blood stream infection, which caused LF and acute renal failure. CONCLUSIONS: We identified two patients with less than 20 cm residual small bowel who died after acute deterioration of liver function. Patients with ultra-short bowel could have a higher risk of LF. Therefore, they should be referred as soon as possible to a specialized hospital where ITx is a choice of treatment for IF.


Assuntos
Intestino Delgado/transplante , Falência Hepática/epidemiologia , Falência Hepática/etiologia , Síndrome do Intestino Curto/complicações , Listas de Espera , Adulto , Doença Crônica , Feminino , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Síndrome do Intestino Curto/mortalidade , Resultado do Tratamento
5.
Transplant Proc ; 48(4): 1282-4, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27320604

RESUMO

BACKGROUND: On the basis of a comparison of the hemolytic complement titer in pigs with that in humans, the complement system of pigs was investigated. The response of innate immunity, such as the natural antibodies, against humans was also examined. METHODS: Hemolytic complement activity of pig serum was measured with the use of a microtitration technique. CH50 was determined according to the method of Mayer. ACH50 was assayed according to the methods of Platts-Milles and Ishizaka. Hemolytic activities of C1, C4, C2, C3, C5, C8, and C9 were estimated through the use of intermediate cells and reagents, as described previously. In addition, the pig natural anti-human antibody was studied with the use of human peripheral blood mononuclear cells (PBMCs). Human PBMCs were stained with 5% pig serum, followed by staining with fluorescein isothiocyanate-labeled goat anti-pig IgG and IgM. The resulting stained cells were quantified by use of a FACScalibur system. The alternative pathway of pig complement was also measured with the use of human erythrocytes and normal pooled pig serum with or without Mg(++)EGTA. RESULTS: Both the CH50 and ACH50 titers were lower than those of humans. Concerning the components, except for C3, each component, that is, C1, C4, C2, C5, C8, and C9, was also lower than that of humans, based on measured values for human complement components. Pig serum clearly contains natural antibodies, IgG and IgM, to human PBMCs. The alternative pathway of pig complement reacted with human erythrocytes. CONCLUSIONS: As a whole, pig innate immunity, the complement system and natural antibody, recognizes the surfaces of human cells.


Assuntos
Proteínas do Sistema Complemento/imunologia , Hemólise/imunologia , Imunidade Inata/imunologia , Animais , Anticorpos Anti-Idiotípicos/metabolismo , Ativação do Complemento/imunologia , Ensaio de Atividade Hemolítica de Complemento , Proteínas do Sistema Complemento/metabolismo , Eritrócitos/imunologia , Fibronectinas/metabolismo , Humanos , Leucócitos Mononucleares/imunologia , Proteínas Recombinantes/metabolismo , Sus scrofa , Suínos
6.
Transplant Proc ; 48(4): 1285-7, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27320605

RESUMO

The inhibitory function of HLA-G1, a class Ib molecule, on monocyte/macrophage-mediated cytotoxicity was examined. The expression of inhibitory receptors that interact with HLA-G, immunoglobulin-like transcript 2 (ILT2), ILT4, and KIR2DL4 (CD158d) on in vitro-generated macrophages obtained from peripheral blood mononuclear cells and the phorbol 12-myristate 13-acetate (PMA)-activated THP-1 cells were examined by flow cytometry. cDNAs of HLA-G1, HLA-G3, HLA-E, and human ß2-microglobulin were prepared, transfected into pig endothelial cells (PECs), and macrophage- and the THP-1 cell-mediated PEC cytolysis was then assessed. In vitro-generated macrophages expressed not only ILT2 and ILT4 but CD158d as well. The transgenic HLA-G1 on PEC indicated a significant suppression in macrophage-mediated cytotoxicity, which was equivalent to that of transgenic HLA-E. HLA-G1 was clearly expressed on the cell surface of PEC, whereas the levels of HLA-G3 were much lower and remained in the intracellular space. On the other hand, the PMA-activated THP-1 cell was less expressed these inhibitory molecules than in vitro-generated macrophages. Therefore, the HLA-G1 on PECs showed a significant but relatively smaller suppression to THP-1 cell-mediated cytotoxicity compared to in vitro-generated macrophages. These results indicate that by generating HLA-G1, but not HLA-G3, transgenic pigs can protect porcine grafts from monocyte/macrophage-mediated cytotoxicity.


Assuntos
Antígenos HLA-G/fisiologia , Leucócitos Mononucleares/imunologia , Macrófagos/imunologia , Animais , Animais Geneticamente Modificados , Antígenos CD/metabolismo , Citocinas/metabolismo , Citotoxicidade Imunológica/fisiologia , Células Endoteliais/imunologia , Endotélio/imunologia , Citometria de Fluxo , Antígenos HLA-G/metabolismo , Humanos , Células Matadoras Naturais/imunologia , Receptor B1 de Leucócitos Semelhante a Imunoglobulina , Glicoproteínas de Membrana/metabolismo , Receptores Imunológicos/metabolismo , Receptores KIR2DL4/metabolismo , Suínos , Transfecção/métodos
7.
Transplant Proc ; 48(4): 1323-5, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27320614

RESUMO

BACKGROUND: In our previous study, we reported on the development of substituting S147C for HLA-E as a useful gene tool for xenotransplantation. In this study we exchanged the codon of HLA-Ev (147), checked its function, and established a line of transgenic mice. METHODS: A new construct, a codon exchanging human HLA-Ev (147) + IRES + human beta 2-microgloblin, was established. The construct was subcloned into pCXN2 (the chick beta-actin promoter and cytomegalovirus enhancer) vector. Natural killer cell- and macrophage-mediated cytotoxicities were performed using the established the pig endothelial cell (PEC) line with the new gene. Transgenic mice with it were next produced using a micro-injection method. RESULTS: The expression of the molecule on PECs was confirmed by the transfection of the plasmid. The established molecules on PECs functioned well in regulating natural killer cell-mediated cytotoxicity and macrophage-mediated cytotoxicity. We have also successfully generated several lines of transgenic mice with this plasmid. The expression of HLA-Ev (147) in each mouse organ was confirmed by assessing the mRNA. The chick beta-actin promoter and cytomegalovirus enhancer resulted in a relatively broad expression of the gene in each organ, and a strong expression in the cases of the heart and lung. CONCLUSION: A synthetic HLA-Ev (147) gene with a codon usage optimized to a mammalian system represents a critical factor in the development of transgenic animals for xenotransplantation.


Assuntos
Animais Geneticamente Modificados/genética , Códon/genética , Antígenos de Histocompatibilidade Classe I/metabolismo , Actinas/genética , Animais , Animais Geneticamente Modificados/imunologia , Linhagem Celular , Citomegalovirus , Células Endoteliais/metabolismo , Elementos Facilitadores Genéticos/genética , Genes Sintéticos , Humanos , Células Matadoras Naturais/fisiologia , Macrófagos/fisiologia , Camundongos , Regiões Promotoras Genéticas/genética , Suínos , Transfecção , Transplante Heterólogo , Antígenos HLA-E
8.
Transplant Proc ; 48(1): 251-4, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26915877

RESUMO

BACKGROUND: Hypercalcemia has been observed in patients after liver transplantation. However, it is rare that the hypercalcemia induced disseminated tissue calcification and heart failure. CASE REPORT: We report a rare case of heart failure caused by disseminated metastatic tissue calcification that involved extensive progressive myocardial calcification after liver transplantation. A 20-year-old man with end-stage liver disease due to biliary atresia underwent ABO-incompatible living donor liver transplantation. After successful transplantation, he suffered from antibody-mediated rejection. Subsequently, ABO-matched cadaveric liver retransplantation was successfully performed. Hypercalcemia developed gradually following the second transplantation. His serum calcium level increased to 18.3 mg/dL with sudden onset of ventricular tachycardia. Although he was resuscitated with a cardiopulmonary support device, he died of heart and liver failure. Histopathologic examination revealed systemic disseminated metastatic tissue calcification, including massive myocardial calcification. CONCLUSION: Progressive worsening of hypercalcemia resulted in disseminated metastatic tissue calcification and massive metastatic myocardial calcification, which led to heart failure after liver transplantation. Because hypercalcemia after liver transplantation can cause fatal tissue calcification, early intervention for hypercalcemia should be considered.


Assuntos
Calcinose/etiologia , Cardiomiopatias/etiologia , Hipercalcemia/etiologia , Falência Hepática/cirurgia , Transplante de Fígado/efeitos adversos , Adulto , Atresia Biliar/complicações , Incompatibilidade de Grupos Sanguíneos/complicações , Cálcio/sangue , Evolução Fatal , Rejeição de Enxerto/complicações , Rejeição de Enxerto/imunologia , Rejeição de Enxerto/cirurgia , Insuficiência Cardíaca/etiologia , Humanos , Fígado/patologia , Falência Hepática/etiologia , Transplante de Fígado/métodos , Doadores Vivos , Masculino , Reoperação/efeitos adversos , Reoperação/métodos , Taquicardia Ventricular/sangue , Taquicardia Ventricular/etiologia
9.
Eur J Neurol ; 23(1): 196-200, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26768678

RESUMO

BACKGROUND AND PURPOSE: A novel TYPE of prion disease associated mainly with autonomic-sensory polyneuropathy was reported by us previously. METHODS: Here the autopsy pathology for patient 1 (the sister) and the clinical characteristics of her younger brother (patient 2) are newly reported. Polymerase chain reaction based restriction fragment length polymorphism analysis of the prion protein gene (PRNP) was performed on both patients and their father (normal control). RESULTS: Polymerase chain reaction based restriction fragment length polymorphism analysis revealed a 2-bp deletion (CT) in codon 178 that causes an additional variable 25 amino acids at the C terminal, from the mutation site to the premature stop codon at codon 203, in both patients 1 and 2 but not in their father. The autopsy of patient 1 showed remarkable prion protein (PrP) deposits in the sympathetic ganglion and peripheral nerves, correlated to her severe autonomic sensory failure. PrP deposits were also found in the central nervous system and peripheral organs such as the heart, lung, stomach, jejunum, ileum, colon, urinary bladder and adrenal gland. The symptoms and biopsy findings of patient 2 were nearly the same as those reported previously for patient 1. His cognitive function was well preserved, but autonomic functions were severely impaired. His biopsied samples showed PrP deposits in the sural nerve and nerve plexuses of the stomach and colon. CONCLUSION: The present unique 2-bp deletion (CT) in codon 178 induced a 'PrP systemic deposition disease' such as pan-autonomic failure, sensory neuropathy and mild cognitive impairment with a specific pathology.


Assuntos
Doenças Priônicas/genética , Príons/genética , Adulto , Códon , Evolução Fatal , Feminino , Humanos , Masculino , Linhagem , Polimorfismo de Fragmento de Restrição , Doenças Priônicas/patologia , Doenças Priônicas/fisiopatologia , Proteínas Priônicas
10.
Eur J Neurol ; 23(2): 339-45, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26493280

RESUMO

BACKGROUND AND PURPOSE: The influence of metabolic syndrome (MetS) on cognitive and affective functions in patients with Alzheimer's disease (AD) was examined. METHODS: A total of 570 AD patients were divided into two subgroups depending on waist circumference (WC) (normal versus achieving Japanese diagnostic criteria of MetS). Afterwards, the AD control subgroup was defined as those normal WC patients with no vascular risk factors (VRFs). The AD with MetS (AD-MetS) subgroup was defined as the MetS WC group who had two or more VRFs to qualify as having MetS. Cognitive and affective functions, insulin resistance, vascular endothelial function and white matter changes between AD-MetS and AD controls were compared. RESULTS: Scores on the Mini-Mental State Examination, Hasegawa Dementia Score-Revised, Frontal Assessment Battery and Montreal Cognitive Assessment were worse in the AD-MetS group than in AD controls, but the difference was not significant. Some analyses were conducted twice, once including all patients and once including only late-elderly patients. Scores on the Geriatric Depression Scale were found to be significantly higher for AD-MetS than for AD controls (all ages, late-elderly), as were those for apathy (late-elderly). Furthermore, both the homeostasis model assessment of insulin resistance and reactive hyperemia index scores were significantly worse in AD-MetS than in AD controls, whilst white matter changes showed a tendency to be worse. CONCLUSIONS: Greater cognitive and affective decline occurs in patients with AD-MetS than in those without. Further, insulin resistance and vascular endothelial dysfunction are strongly correlated with AD-MetS before pathological white matter changes can be observed.


Assuntos
Doença de Alzheimer/patologia , Doença de Alzheimer/fisiopatologia , Síndrome Metabólica/patologia , Síndrome Metabólica/fisiopatologia , Substância Branca/patologia , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/epidemiologia , Apatia/fisiologia , Comorbidade , Depressão/epidemiologia , Depressão/fisiopatologia , Feminino , Humanos , Japão/epidemiologia , Masculino , Síndrome Metabólica/epidemiologia
11.
J Neurol Sci ; 350(1-2): 14-7, 2015 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25662676

RESUMO

In addition to cognitive impairment, behavioral and psychological symptoms of dementia (BPSD) are another important aspect of most dementia patients. This study was designed for a new simple assessment of BPSD. We first employed a clinical survey for the local community with sending an inquiry letter to all members (n=129) of dementia caregiver society, and then attempted to create a new BPSD score for dementia with 10 BPSD items. This new simple BPSD score was compared to a standard-detailed BPSD score neuropsychiatric inventory (NPI) for a possible correlation (n=792) and a time to complete (n=136). Inter-rater reliability was examined comparing scores between main and second caregivers (n=70) for AD. Based on the clinical survey for local caregivers, a new BPSD score for dementia (ABS, Abe's BPSD score) was newly created, in which each BPSD item was allotted by an already-weighted score (maximum 1-9) based on the frequency and severity, and was finalized with taking temporal occurrences into account. ABS was filled by the main caregiver with a full score of 44, was well correlated with NPI (r=0.716, **p<0.01) in 792 AD patients (age 78.6 ± 7.0 years, MMSE 19.0 ± 5.9), and took a shorter time as only 56.8 ± 38.8s (**p<0.01) than NPI score (132.7 ± 94.0 s) with 136 AD patients. A high inter-rater reliability was obtained (r=0.964, **p<0.01) with a little smaller score (0.877 time) of ABS in secondary than the main caregivers. ABS provides a new simple and quick test for BPSD assessment, with a good correlation to NPI but a shorter time, and with a high inter-rater reliability. Thus ABS is useful for evaluating BPSD for mild to moderate dementia patients.


Assuntos
Sintomas Comportamentais/diagnóstico , Sintomas Comportamentais/psicologia , Demência/diagnóstico , Demência/psicologia , Testes Neuropsicológicos/normas , Índice de Gravidade de Doença , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes
12.
Eur J Neurol ; 22(2): 313-21, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25220803

RESUMO

BACKGROUND AND PURPOSE: Diabetes mellitus (DM) is associated with a decline in cognitive and affective functions. METHODS: In all, 182 outpatients with DM were investigated for associations of cognitive and affective functions with diabetes-related factors and cerebral white matter abnormalities. In addition, the difference in cognitive decline of age-matched late elderly normal subjects and DM patients was investigated. RESULTS: The present study revealed that cognitive and affective functions declined in some DM patients. Furthermore, the decline in these functions was unrelated to fasting blood sugar level but was related to glycosylated hemoglobin (HbA1c) and insulin resistance. Poor HbA1c control was associated with a significant decline in the 'calculation' subscale and insulin resistance for 'naming', 'read list of letters' and 'delayed recall' Montreal Cognitive Assessment (MoCA) subscale scores. Magnetic resonance imaging scans showed that both periventricular hyperintensity (PVH) and deep white matter hyperintensity were associated with Mini Mental State Examination (MMSE) and MoCA scores, but only PVH was related to homeostasis model assessment of insulin resistance scores. Compared with age-matched late elderly normal subjects, 'orientation to time' and 'registration' MMSE subscales declined in late elderly DM patients. CONCLUSIONS: These results suggest that cognitive and affective decline in DM patients was mostly related to glucose control and insulin resistance, whilst amongst late elderly subjects the impairment of 'attention' and 'orientation' were characteristic features of DM patients.


Assuntos
Envelhecimento/patologia , Transtornos Cognitivos/etiologia , Complicações do Diabetes , Substância Branca/patologia , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/sangue , Transtornos Cognitivos/patologia , Transtornos Cognitivos/fisiopatologia , Complicações do Diabetes/sangue , Complicações do Diabetes/patologia , Complicações do Diabetes/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
13.
Eur J Neurol ; 21(11): 1377-86, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24985895

RESUMO

BACKGROUND AND PURPOSE: Spinocerebellar ataxia type 36 (SCA36), also called Asidan, is an autosomal-dominant neurodegenerative disorder identified as a hexanucleotide GGCCTG repeat expansion in the first intron 1 of the NOP56 gene. In the present study, for the first time an autopsy sample from an Asidan patient was examined and cytoplasmic inclusions and (GGCCUG)n repeat RNA foci were detected. METHODS: Hematoxylin and eosin staining, immunohistochemical staining, as well as fluorescence in situ hybridization were used to investigate the cytoplasmic inclusions of ubiquitin and p62 and the (GGCCUG)n repeat RNA foci. RESULTS: The present study showed both ubiquitin- and p62-positive inclusions in the cytoplasm of the inferior olivary nucleus of the Asidan patient, (GGCCUG)n RNA foci in neuronal nuclei of the cerebrum, cerebellum, inferior olive, spinal cord and temporal muscle, and three types of RNA foci, i.e. single small, multiple small and giant. Of interest is that the giant RNA foci, nearly 10 µm in diameter, that were detected in Purkinje cells, spinal motor neurons and most frequently in the inferior olivary nucleus, may be responsible for pivotal clinical symptoms of Asidan. CONCLUSIONS: The present study is the first report to show neuronal cytoplasmic inclusion bodies and giant RNA foci in an Asidan patient. The relationships between the giant RNA foci and neurodegeneration have yet to be studied.


Assuntos
RNA/genética , Sequências Repetitivas de Ácido Nucleico/genética , Ataxias Espinocerebelares/genética , Idoso de 80 Anos ou mais , Humanos , Masculino
14.
Philos Trans A Math Phys Eng Sci ; 372(2020)2014 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-24936006

RESUMO

The applications and implications of two recently addressed asymptotic descriptions of exact coherent structures in shear flows are discussed. The first type of asymptotic framework to be discussed was introduced in a series of papers by Hall & Smith in the 1990s and was referred to as vortex-wave interaction theory (VWI). New results are given here for the canonical VWI problem in an infinite region; the results confirm and extend the results for the infinite problem inferred the recent VWI computation of plane Couette flow. The results given define for the first time exact coherent structures in unbounded flows. The second type of canonical structure described here is that recently found for asymptomatic suction boundary layer and corresponds to freestream coherent structures (FCS), in boundary layer flows. Here, it is shown that the FCS can also occur in flows such as Burgers vortex sheet. It is concluded that both canonical problems can be locally embedded in general shear flows and thus have widespread applicability.

15.
Sci Technol Adv Mater ; 15(5): 055007, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27877719

RESUMO

The transport and magnetic properties of the tetragonal Fe[Formula: see text]S were investigated using magnetoresistivity and magnetization within [Formula: see text] K, [Formula: see text] 70 kOe and [Formula: see text] 3.0 GPa. In addition, room-temperature x-ray diffraction and photoelectron spectroscopy were also applied. In contrast to previously reported nonmetallic character, Fe[Formula: see text]S is intrinsically metallic but due to a presence of a weak localization such metallic character is not exhibited below room temperature. An applied pressure reduces strongly this additional resistive contribution and as such enhances the temperature range of the metallic character which, for ∼3 GPa, is evident down to 75 K. The absence of superconductivity as well as the mechanism behind the weak localization will be discussed.

17.
Artigo em Inglês | MEDLINE | ID: mdl-23679523

RESUMO

Interactions between nearly bicritical modes in Taylor-Couette flow, which have been concerned with the framework of weakly nonlinear theory, are extended to fully nonlinear Navier-Stokes computation. For this purpose, a standard Newton solver for axially periodic flows is generalized to compute any mixed solutions having up to two phases, which typically arise from interactions of two spiral or Taylor vortex modes. Also, a simple theory is developed in order to classify the mixed solutions. With these methods, we elucidate pattern formation phenomena, which have been observed in a Taylor-Couette flow experiment. Focusing on the counter-rotating parameter range, all possible classes of interaction of various solutions with different azimuthal and axial wave numbers are considered within our computational restriction, and we observe numerous connection branches, e.g., footbridge solutions. Some of the mixed solutions result in a three-dimensional wavy spiral solution with axial relative periodicity or an axially doubly periodic toroidally closed vortex solution. The possible connection of the former solution family to spiral turbulence, which has been observed in highly counter-rotating Taylor-Couette flow, is discussed.

19.
Neuroscience ; 221: 47-55, 2012 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-22766232

RESUMO

Reactive oxygen species (ROS) are major exacerbation factor in acute ischemic stroke, and thrombolytic agent tissue plasminogen activator (tPA) may worsen motor function and cerebral infarcts. The platinum nanoparticle (nPt) is a novel ROS scavenger, and thus we examined the clinical and neuroprotective effects of nPt in ischemic mouse brains. Mice were subjected to transient middle cerebral artery occlusion (tMCAO) for 60 min and divided into the following four groups by intravenous administration upon reperfusion, vehicle, tPA, tPA+nPt, and nPt. At 48 h after tMCAO, motor function, infarct volume, immunohistochemical analyses of neurovascular unit (NVU), in vivo imaging of matrix metalloproteinase (MMP), and zymography for MMP-9 activity were examined. Superoxide anion generation at 2h after tMCAO was also examined with hydroethidine (HEt). As a result, administration of tPA deteriorated the motor function and infarct volume as compared to vehicle. In vivo optical imaging of MMP showed strong fluorescent signals in affected regions of tMCAO groups. Immunohistochemical analyses revealed that tMCAO resulted in a minimal decrease of NAGO and occludin, but a great decrease of collagen IV and a remarkable increase of MMP-9. HEt stain showed increased ROS generation by tMCAO. All these results became pronounced with tPA administration, and were greatly reduced by nPt. The present study demonstrates that nPt treatment ameliorates neurological function and brain damage in acute cerebral infarction with neuroprotective effect on NVU and inactivation of MMP-9. The strong reduction of ROS production by nPt could account for these remarkable neurological and neuroprotective effects against ischemic stroke.


Assuntos
Infarto Encefálico/induzido quimicamente , Infarto Encefálico/prevenção & controle , Infarto da Artéria Cerebral Média/tratamento farmacológico , Nanopartículas Metálicas/uso terapêutico , Platina/uso terapêutico , Ativador de Plasminogênio Tecidual/efeitos adversos , Animais , Colágeno Tipo IV/metabolismo , Modelos Animais de Doenças , Esquema de Medicação , Fluxometria por Laser-Doppler , Masculino , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Transtornos dos Movimentos/etiologia , Transtornos dos Movimentos/prevenção & controle , Fenantridinas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Fluxo Sanguíneo Regional/efeitos dos fármacos , Reperfusão , Espectroscopia de Luz Próxima ao Infravermelho , Superóxidos/metabolismo , Fatores de Tempo
20.
Phys Rev Lett ; 108(6): 066403, 2012 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-22401093

RESUMO

From detailed angle-resolved NMR and Meissner measurements on a ferromagnetic (FM) superconductor UCoGe (T(Curie)∼2.5 K and T(SC)∼0.6 K), we show that superconductivity in UCoGe is tightly coupled with longitudinal FM spin fluctuations along the c axis. We found that magnetic fields along the c axis (H∥c) strongly suppress the FM fluctuations and that the superconductivity is observed in the limited magnetic-field region where the longitudinal FM spin fluctuations are active. These results, combined with model calculations, strongly suggest that the longitudinal FM spin fluctuations tuned by H∥c induce the unique spin-triplet superconductivity in UCoGe. This is the first clear example that FM fluctuations are intimately related with superconductivity.

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