Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 31
Filtrar
Mais filtros

País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Phys Rev Lett ; 129(21): 216402, 2022 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-36461982

RESUMO

Materials hosting kagome lattices have drawn interest for the diverse magnetic and electronic states generated by geometric frustration. In the AV_{3}Sb_{5} compounds (A=K, Rb, Cs), stacked vanadium kagome layers give rise to unusual charge density waves (CDW) and superconductivity. Here we report single-crystal growth and characterization of ScV_{6}Sn_{6}, a hexagonal HfFe_{6}Ge_{6}-type compound that shares this structural motif. We identify a first-order phase transition at 92 K. Single crystal x-ray and neutron diffraction reveal a charge density wave modulation of the atomic lattice below this temperature. This is a distinctly different structural mode than that observed in the AV_{3}Sb_{5} compounds, but both modes have been anticipated in kagome metals. The diverse HfFe_{6}Ge_{6} family offers more opportunities to tune ScV_{6}Sn_{6} and explore density wave order in kagome lattice materials.

2.
Kyobu Geka ; 75(11): 951-954, 2022 Oct.
Artigo em Japonês | MEDLINE | ID: mdl-36176256

RESUMO

A 67-year-old male underwent ascending aortic replacement for Stanford type A acute aortic dissection four years ago. Residual false lumen in the aortic root and mild to moderate aortic regurgitation were noted postoperatively. Two and a half years later, he presented with hemolytic anemia and shortness of breath. Computed tomography (CT) revealed aneurysmal aortic root and severely kinked vascular prosthesis, and echocardiography showed severe aortic regurgitation. It was considered that the proximal residual false lumen gradually enlarged, and the graft was pushed up distally and kinked, resulting in hemolytic anemia. Surgical treatment was indicated because of deteriorating shortness of breath due to hemolytic anemia (Hb 6.7 g/dl, LDH 1,528 U/l) and aortic regurgitation. Aortic root replacement was successfully performed and hemolytic anemia improved immediately after surgery.


Assuntos
Anemia Hemolítica , Aneurisma da Aorta Torácica , Dissecção Aórtica , Insuficiência da Valva Aórtica , Implante de Prótese Vascular , Idoso , Anemia Hemolítica/diagnóstico por imagem , Anemia Hemolítica/etiologia , Anemia Hemolítica/cirurgia , Dissecção Aórtica/complicações , Dissecção Aórtica/diagnóstico por imagem , Dissecção Aórtica/cirurgia , Aneurisma da Aorta Torácica/cirurgia , Insuficiência da Valva Aórtica/diagnóstico por imagem , Insuficiência da Valva Aórtica/etiologia , Insuficiência da Valva Aórtica/cirurgia , Prótese Vascular/efeitos adversos , Implante de Prótese Vascular/efeitos adversos , Dispneia , Humanos , Masculino , Resultado do Tratamento
3.
BMC Infect Dis ; 19(1): 927, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31684875

RESUMO

BACKGROUND: Capnocytophaga canimorsus is a gram-negative bacterium and an oral commensal in dogs and cats, but occasionally causes serious infections in humans. Septicemia is one of the most fulminant forms, but diagnosis of C. canimorsus infection is often difficult mainly because of its very slow growth. C. canimorsus infective endocarditis (IE) is rare and is poorly understood. Since quite a few strains produce ß-lactamase, antimicrobial susceptibility is pivotal information for adequate treatment. We herein report a case with C. canimorsus IE and the results of drug susceptibility test. CASE PRESENTATION: A 46-year-old man had a dog bite in his left hand 3 months previously. The patient was referred to our hospital for fever (body temperature > 38 °C), visual disturbance, and dyspnea. Echocardiography showed aortic valve regurgitation and vegetation on the leaflets. IE was diagnosed, and we initially administered cefazolin and gentamycin assuming frequently encountered microorganisms and the patient underwent aortic valve replacement. C. canimorsus was detected in the aortic valve lesion and blood cultures. It was also identified by 16S ribosome DNA sequencing. Ceftriaxone were started and continued because disk diffusion test revealed the isolate was negative for ß-lactamase and this case had cerebral symptoms. The patient successfully completed antibiotic treatment following surgery. CONCLUSIONS: We diagnosed C. canimorsus sepsis and IE by extended-period blood cultures and 16S ribosome DNA sequencing by polymerase chain reaction, and successfully identified its drug susceptibility.


Assuntos
Mordeduras e Picadas/complicações , Capnocytophaga/patogenicidade , Endocardite Bacteriana/etiologia , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Infecções por Bactérias Gram-Negativas/etiologia , Infecções por Bactérias Gram-Negativas/terapia , Animais , Antibacterianos/uso terapêutico , Hemocultura , Capnocytophaga/genética , Cefazolina/uso terapêutico , Ceftriaxona/uso terapêutico , Cães , Endocardite Bacteriana/tratamento farmacológico , Endocardite Bacteriana/microbiologia , Endocardite Bacteriana/terapia , Gentamicinas/uso terapêutico , Infecções por Bactérias Gram-Negativas/microbiologia , Próteses Valvulares Cardíacas , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase/métodos , Sepse/tratamento farmacológico , beta-Lactamases
4.
J Artif Organs ; 19(4): 387-391, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27401710

RESUMO

We successfully controlled infection of a left ventricular assist device by performing pump exchange. A 53-year-old man was implanted with DuraHeart for ischemic cardiomyopathy as a bridge to transplantation. Two years later, he was hospitalized with the diagnosis of driveline infection. The blood cultures detected Pseudomonas aeruginosa. During the admission, he developed brain hemorrhage perhaps due to septic emboli. The chest computed tomography scan revealed a small defect inside the outflow graft of the DuraHeart, which was highly suspected of vegetation. He underwent pump exchange, from DuraHeart to Jarvik 2000 with concomitant omentopexy. His postoperative course was uneventful, and he was discharged with no sequela of the brain hemorrhage. Four months after the pump exchange, he successfully underwent heart transplantation. No infectious tissue was observed in the pericardial space at the time of heart transplantation. Pump exchange is an effective way to manage refractory left ventricular assist device infection, and the timing of surgical intervention is of great importance.


Assuntos
Insuficiência Cardíaca/cirurgia , Coração Auxiliar/efeitos adversos , Infecções por Pseudomonas/etiologia , Transplante de Coração , Humanos , Masculino , Pessoa de Meia-Idade , Infecções por Pseudomonas/terapia , Pseudomonas aeruginosa/isolamento & purificação
5.
Proc Natl Acad Sci U S A ; 110(29): 11720-4, 2013 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-23818624

RESUMO

High pressure plays an increasingly important role in both understanding superconductivity and the development of new superconducting materials. New superconductors were found in metallic and metal oxide systems at high pressure. However, because of the filled close-shell configuration, the superconductivity in molecular systems has been limited to charge-transferred salts and metal-doped carbon species with relatively low superconducting transition temperatures. Here, we report the low-temperature superconducting phase observed in diamagnetic carbon disulfide under high pressure. The superconductivity arises from a highly disordered extended state (CS4 phase or phase III[CS4]) at ~6.2 K over a broad pressure range from 50 to 172 GPa. Based on the X-ray scattering data, we suggest that the local structural change from a tetrahedral to an octahedral configuration is responsible for the observed superconductivity.


Assuntos
Dissulfeto de Carbono/química , Condutividade Elétrica , Conformação Molecular , Pressão , Espalhamento de Radiação , Temperatura
6.
Nature ; 458(7235): 186-9, 2009 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-19279633

RESUMO

Lithium, the lightest metal, has long been considered to have a 'simple' electronic structure that can be well explained within the nearly-free-electron model. But lithium does not stay 'simple' under compression: rather than becoming more free-electron-like as pressure is increased, first-principles calculations suggest that it transforms into a semi-metal or semiconductor. Experimentally, it has been shown that dense lithium adopts low-symmetry structures; there is also evidence that its resistivity increases with pressure. However, the electronic transport properties of lithium have so far not been directly monitored as a function of increasing static pressure. Here we report electrical resistance measurements on lithium in a diamond anvil cell up to pressures of 105 GPa, which reveal a significant increase in electrical resistivity and a change in its temperature dependence near 80 GPa. Our data thus provide unambiguous experimental evidence for a pressure-induced metal-to-semiconductor transition in a 'simple' metallic element.

7.
Phys Rev Lett ; 110(23): 235501, 2013 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-25167509

RESUMO

The recently discovered high pressure phase VII of calcium [M. Sakata et al., Phys. Rev. B 83, 220512(R) (2011)] has the highest superconducting transition temperature (T(c)) of 29 K among all the elements. Understanding the cause for such a high T(c) state is necessary to clarify its crystal structure. The structure of this phase was determined by an x-ray powder diffraction experiment and a density functional theory calculation and was not found to be the usual host-guest type but consisted of a 2×2 supercell in the tetragonal ab plane with a commensurate host-guest ratio of 4/3 along the c axis containing 128 atoms.

8.
J Chem Phys ; 139(10): 104701, 2013 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-24050356

RESUMO

Low-temperature and high-pressure experiments were performed with filled ice Ih structure of methane hydrate under 2.0-77.0 GPa and 30-300 K using diamond anvil cells and a helium-refrigeration cryostat. In situ X-ray diffractometry revealed distinct changes in the compressibility of the axial ratios of the host framework with pressure. Raman spectroscopy showed a split in the C-H vibration modes of the guest methane molecules, which was previously explained by the orientational ordering of the guest molecules. The pressure and temperature conditions at the split of the vibration modes agreed well with those of the compressibility change. The results indicate the following: (i) the orientational ordering of the guest methane molecules from an orientationally disordered state occurred at high pressures and low temperatures; and (ii) this guest ordering led to anisotropic contraction in the host framework. Such guest orientational ordering and subsequent anisotropic contraction of the host framework were similar to that reported previously for filled ice Ic hydrogen hydrate. Since phases with different guest-ordering manners were regarded as different phases, existing regions of the guest disordered-phase and the guest ordered-phase were roughly estimated by the X-ray study. In addition, above the pressure of the guest-ordered phase, another high-pressure phase developed in the low-temperature region. The deuterated-water host samples were also examined, and the influence of isotopic effects on guest ordering and phase transformation was observed.

9.
Kyobu Geka ; 66(2): 129-32, 2013 Feb.
Artigo em Japonês | MEDLINE | ID: mdl-23381360

RESUMO

A 61-year-old man suddenly developed transient left hemiplegia and consciousness disturbance. Computed tomography showed acute Stanford type A aortic dissection. Dissection affected the entire right common carotid artery, and its false lumen extremely compressed the true lumen. The right common carotid artery, along with the right femoral and the left axillary arteries, was used as an inflow of cardiopulmonary bypass during emergency surgery. The ascending aorta that included a large intimal tear was replaced. However, systemic reperfusion either through the femoral artery or through a side branch of vascular prosthesis failed to restore the right cerebral blood flow due to persistent true lumen obstruction by the expanded false lumen in the innominate artery. Therefore, ascending aorta-right carotid artery bypass using that side branch was performed immediately. Though temporary cerebral malperfusion could cause dismal outcome, direct carotid artery cannulation played a key role in this successfully-treated patient.


Assuntos
Aneurisma Aórtico/cirurgia , Dissecção Aórtica/cirurgia , Artéria Carótida Primitiva , Cateterismo/métodos , Transtornos Cerebrovasculares/etiologia , Artéria Carótida Primitiva/cirurgia , Transtornos Cerebrovasculares/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias
10.
J Chem Phys ; 137(7): 074505, 2012 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-22920129

RESUMO

Low-temperature and high-pressure experiments were performed on the filled ice Ic structure of hydrogen hydrate at previously unexplored conditions of 5-50 GPa and 30-300 K using diamond anvil cells and a helium-refrigeration cryostat. In situ x-ray diffractometry revealed that the cubic filled ice Ic structure transformed to tetragonal at low temperatures and high pressures; the axis ratio of the tetragonal phase changed depending on the pressure and temperature. These results were consistent with theoretical predictions performed via first principle calculations. The tetragonal phase was determined to be stable above 20 GPa at 300 K, above 15 GPa at 200 K, and above 10 GPa at 100 K. Further changes in the lattice parameters were observed from about 45-50 GPa throughout the temperature region examined, which suggests the transformation to another high-pressure phase above 50 GPa. In our previous x-ray study that was performed up to 80 GPa at room temperature, a similar transformation was observed above 50 GPa. In this study, the observed change in the lattice parameters corresponds to the beginning of that transformation. The reasons for the transformation to the tetragonal structure are briefly discussed: the tetragonal structure might be induced due to changes in the vibrational or rotational modes of the hydrogen molecules under low temperature and high pressure.

11.
Sci Rep ; 12(1): 17377, 2022 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-36253452

RESUMO

Suicide is a serious public health problem, and it is urgent to identify biomarkers associated with suicide to prevent it. We aimed to clarify the association across suicidal behavior, personality traits, and brain activation by emotional stimulation tasks using near-infrared spectroscopy (NIRS) in patients with mood disorders. 11 mood disorder patients with a history of suicide attempt (MDSA), 18 mood disorder patients with no history of suicide attempt (MDNSA), and 17 healthy individuals were studied. The MDSA patients showed significantly high impulsivity and hopeless compared to healthy subjects, great response to the thread word task in the orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC) compared to MDNSA patients, and the significant correlation between the personality traits and brain activation. The MDNSA did not show the trend. The results suggest that the personality traits and the activation of OFC and DLPFC during the negative emotional cognitive stimuli is associated with suicidal behavior, indicating the findings are involved in the pathophysiology of suicidality in mood disorders.


Assuntos
Transtornos do Humor , Ideação Suicida , Cognição , Humanos , Personalidade , Córtex Pré-Frontal , Tentativa de Suicídio/psicologia
12.
Intern Med ; 60(7): 993-998, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33790140

RESUMO

Objective Primary aldosteronism (PA) is a major cause of secondary hypertension. The association between PA and other hormone disorders is unclear. The present study aimed to evaluate whether the parathyroid hormone (PTH) value is associated with PA subtypes or specific treatments. Methods We enrolled 135 patients with PA who had their PTH value measured before undergoing a specific treatment. We evaluated whether PTH value is associated with PA subtypes or with specific treatments. The present study is a single-center retrospective study (2011-2018). Results Our study showed that, among the patients with PA, the proportion of those with PTH elevation was >30%. The PTH value was significantly correlated with both the basal plasma aldosterone concentration (PAC) and PAC after a captopril challenge test. However, the PTH value was not significantly different between the patients with unilateral and bilateral PA. We observed that the serum PTH value decreased after treatment of PA with unilateral adrenalectomy or mineralocorticoid receptor antagonists. Conclusion Our findings suggest that the PTH value in PA patients might be associated with the autonomous production of aldosterone. However, there was no correlation between the PTH value and PA subtypes in our study. Additionally, our study showed that targeted treatment for PA may lead to a decrease in the serum PTH levels. Hence, the PTH value could potentially be used as an index for measuring the suitability for PA treatment.


Assuntos
Hiperaldosteronismo , Hipertensão , Aldosterona , Cálcio , Humanos , Hiperaldosteronismo/complicações , Hiperaldosteronismo/diagnóstico , Hormônio Paratireóideo , Estudos Retrospectivos
13.
Kyobu Geka ; 63(3): 208-11, 2010 Mar.
Artigo em Japonês | MEDLINE | ID: mdl-20214349

RESUMO

Osteogenesis imperfecta (OI) is a hereditary systemic connective tissue disorder that is rarely associated with valvular heart diseases. Cardiovascular surgery for patients with OI carries high morbidity and mortality, which mostly results from bleeding tendencies caused by tissue and capillary fragility. We report a 47-year-old male with isolated aortic regurgitation, who underwent aortic valve replacement (AVR) with a mechanical prosthesis without blood transfusion. The perioperative course was uneventful. We believe that a meticulous technique and a planned strategy to avoid every damage to fragile tissues, particularly to bones, are very important during surgery for patients with OI.


Assuntos
Implante de Prótese de Valva Cardíaca/métodos , Osteogênese Imperfeita/complicações , Valva Aórtica/cirurgia , Insuficiência da Valva Aórtica/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade
14.
Kyobu Geka ; 63(10): 853-6, 2010 Sep.
Artigo em Japonês | MEDLINE | ID: mdl-20845692

RESUMO

A 37-year-old woman underwent semi-emergency mitral valve plasty for severe mitral regurgitation and congestive heart failure. Although repair was successfully performed and the left ventricular function was maintained, refractory pulmonary hypertension precluded cessation of cardiopulmonary bypass. Inhalation of nitric oxide was ineffective, and assist circulation was required. All data obtained from the Swan-Ganz catheter and other routine monitors were devastating, and the patient showed no clinical recovery in the early postoperative period. However, transesophageal echocardiography (TEE) performed on the 2nd postoperative day (POD) revealed much better filling of the left heart and the patient was weaned from assist circulation on the 4th POD. Pulmonary vascular disease was denied histologically. Late cardiac catheterization disclosed normal pulmonary artery pressure and resistance. TEE played a key role during very complicated postoperative management. Monitoring of the left atrial pressure might be necessary in cases that require assist circulation due to pulmonary vasoconstriction.


Assuntos
Circulação Assistida , Hipertensão Pulmonar/etiologia , Hipertensão Pulmonar/terapia , Insuficiência da Valva Mitral/cirurgia , Adulto , Feminino , Humanos , Valva Mitral/cirurgia , Complicações Pós-Operatórias
15.
Front Hum Neurosci ; 14: 570279, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33568977

RESUMO

Dysfunctional attentional control is observed in patients with mental disorders. However, there is no established neurophysiological method to assess attention in such patients. We showed a discrepancy in alpha-band power in the tasks that evoked internal and external attention event-related alpha-band power changes in healthy subjects during self-reflection (SR) and working memory (WM) tasks in a preliminary study. In this study, we aimed at elucidating event-related alpha-band power changes in healthy subjects during the tasks, addressing the shortcomings of the previous study. Sixteen healthy volunteers were examined for the event-related power (ERpow) change during the tasks. The results demonstrated the discrepancy of alpha-band ERpow at 8, 10, and 12 Hz in the parieto-occipital area between the WM and SR tasks for a period between a target stimulus and a command stimulus, where a participant switched to internal attention from external attention according to the SR task and remained at external attention according to the WM task. The results suggest that alpha-band ERpow in this area is associated with the direction of attention in response to cognitive stimuli, indicating that the findings of ERpow during the two tasks would potentially aid in the clarification of the pathophysiology of the dysfunctional change in attention in patients with psychiatric disorders.

16.
Hokkaido Igaku Zasshi ; 84(3): 177-82, 2009 May.
Artigo em Japonês | MEDLINE | ID: mdl-19507556

RESUMO

To achieve good care for stroke patients in the Hokumou Secondary Medical District, we reaffirmed the current status of the services, discovered the keypoints and issues, and searched for solutions to the current problems. The population, its age composition and the number of beds occupied by stroke patients--stratified in acute, convalescent and maintenance stages-were surveyed. The number of patients suffering from stroke under the jurisdiction of this district was compiled, by using the "regional alliance path for stroke," and the severity and outcome of each case were evaluated by using the mRS (modified Rankin Scale). We held seminars for citizens' on the prevention and management of stroke and the attendees were asked to fill out questionnaires, and were organized: networks for medical care and nursing in the Okhotsk Sea area and people's voices were heard at the network meetings; and at the town meetings held at Kitami, Abashiri and Bihoro, the challenges and problems in each area were discussed. The findings obtained from these activities were compiled for the current study. The rate of release of the patients to their home environment was high in the acute stage but low in the convalescent stage. To substantiate the regional management of stroke patients, it is essential that one be familiar with the availability of the limited medical recourses for and dynamics of patients. And yet, there is a limit to the efforts that the medical profession alone can make for the acute and convalescent stages. It is necessary that the health services assist in solving the problems, with the cooperation of the citizens and the nursing network that is involved in homes and nursing facilities for the care of patients in the maintenance stage.


Assuntos
Serviços de Saúde Comunitária/organização & administração , Serviços de Saúde Comunitária/estatística & dados numéricos , Procedimentos Clínicos/estatística & dados numéricos , Acidente Vascular Cerebral , Adolescente , Adulto , Idoso , Humanos , Japão/epidemiologia , Pessoa de Meia-Idade , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/enfermagem , Acidente Vascular Cerebral/terapia , Reabilitação do Acidente Vascular Cerebral , Inquéritos e Questionários , Adulto Jovem
17.
J Phys Condens Matter ; 31(18): 185501, 2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-30731441

RESUMO

We report the high-pressure behavior of plasmon in polycrystalline Li up to 15 GPa at room temperature studied by inelastic x-ray scattering and ab initio calculation. The plasmon energy ([Formula: see text]) increases with decreasing atomic volume ([Formula: see text]), and the [Formula: see text] slope exhibits a discontinuity at bcc → fcc structural phase boundary reflecting the electronic band structure change. The plasmon peak width ([Formula: see text]) versus momentum transfer (q) curve of bcc-Li below 6.5 GPa keeps similar parabola-like shape. Above 8.4 GPa, where Li is in fcc, it changes from that of bcc-Li and has a convex shape.

18.
Brain ; 129(Pt 3): 791-808, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16364955

RESUMO

Clinical recovery after stroke can be significant and has been attributed to plastic reorganization and recruitment of novel areas previously not engaged in a given task. As equivocal results have been reported in studies using single imaging or electrophysiological methods, here we applied an integrative multimodal approach to a group of well-recovered chronic stroke patients (n = 11; aged 50-81 years) with left capsular lesions. Focal activation during recovered hand movements was assessed with EEG spectral analysis and H2(15)O-PET with EMG monitoring, cortico-cortical connectivity with EEG coherence analysis (cortico-cortical coherence) and corticospinal connectivity with transcranial magnetic stimulation (TMS). As seen from comparisons with age-matched controls, our patients showed enhanced recruitment of the lateral premotor cortex of the lesioned hemisphere [Brodmann area (BA) 6], lateral premotor and to a lesser extent primary sensorimotor and parietal cortex of the contralesional hemisphere (CON-H; BA 4 and superior parietal lobule) and left cerebellum (patients versus controls, Z > 3.09). EEG coherence analysis showed that after stroke cortico-cortical connections were reduced in the stroke hemisphere but relatively increased in the CON-H (ANOVA, contrast analysis, P < 0.05), suggesting a shift of functional connectivity towards the CON-H. Nevertheless, fast conducting corticospinal transmission originated exclusively from the lesioned hemisphere. No direct ipsilateral motor evoked potentials (MEPs) could be elicited with TMS over the contralesional primary motor cortex (iM1) in stroke patients. We conclude that (i) effective recovery is based on enhanced utilization of ipsi- and contralesional resources, (ii) basic corticospinal commands arise from the lesioned hemisphere without recruitment of ('latent') uncrossed corticospinal tract fibres and (iii) increased contralesional activity probably facilitates control of recovered motor function by operating at a higher-order processing level, similar to but not identical with the extended network concerned with complex movements in healthy subjects.


Assuntos
Córtex Motor/fisiopatologia , Plasticidade Neuronal , Acidente Vascular Cerebral/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Mapeamento Encefálico/métodos , Circulação Cerebrovascular , Doença Crônica , Eletroencefalografia , Potencial Evocado Motor , Feminino , Mãos/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Motor/patologia , Movimento , Tomografia por Emissão de Pósitrons , Acidente Vascular Cerebral/patologia , Reabilitação do Acidente Vascular Cerebral , Estimulação Magnética Transcraniana
19.
Sci Adv ; 1(9): e1500669, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26601304

RESUMO

Contrary to the empirical Miedema and Hume-Rothery rules and a recent theoretical prediction, we report experimental evidence on the formation of Li-Cs alloys at very low pressure (>0.1 GPa). We also succeeded in synthesizing a pure nonstoichiometric and ordered crystalline phase from an approximately equimolar mixture and resolved its structure using the maximum entropy method. The new alloy has a primitive cubic cell with the Li atom situated in the center and the Cs at the corners. This structure is stable to at least 10 GPa and has an anomalously high coefficient of thermal expansion at low pressure. Analysis of the valence charge density shows that electrons are donated from Cs to the Li "p"-orbitals, resulting in a rare formal oxidation state of -1 for Li. The observation indicates the diversity in the bonding of the seeming simple group I Li element.

20.
Sci Rep ; 5: 16560, 2015 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-26548442

RESUMO

We investigated the phase transformation of hot dense fluid hydrogen using static high-pressure laser-heating experiments in a laser-heated diamond anvil cell. The results show anomalies in the heating efficiency that are likely to be attributed to the phase transition from a diatomic to monoatomic fluid hydrogen (plasma phase transition) in the pressure range between 82 and 106 GPa. This study imposes tighter constraints on the location of the hydrogen plasma phase transition boundary and suggests higher critical point than that predicted by the theoretical calculations.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA