Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
Acta Crystallogr A Found Adv ; 76(Pt 5): 600-610, 2020 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-32869758

RESUMEN

Primitive substitution tilings on {\bb R} whose expansion maps are unimodular are considered. It is assumed that all the eigenvalues of the expansion maps are algebraic conjugates with the same multiplicity. In this case, a cut-and-project scheme can be constructed with a Euclidean internal space. Under some additional condition, it is shown that if the substitution tiling has pure discrete spectrum, then the corresponding representative point sets are regular model sets in that cut-and-project scheme.

2.
Acta Crystallogr A Found Adv ; 75(Pt 3): 584-592, 2019 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-31041912

RESUMEN

For the group algebra of the finite non-crystallographic Coxeter group of type H4, its Gröbner-Shirshov basis is constructed as well as the corresponding standard monomials, which describe explicitly all symmetries acting on the 120-cell and produce a natural operation table between the 14400 elements for the group.

3.
ACS Sens ; 4(4): 1097-1102, 2019 04 26.
Artículo en Inglés | MEDLINE | ID: mdl-30848593

RESUMEN

A single walled carbon nanotube (SWCNT) based γ ray detector is demonstrated without a conventional scintillation mechanism. The change in the conductance of a two terminal SWCNT resistor in response to γ ray exposure is exploited as a sensing mechanism. Radiation-induced ambient oxygen dissociation and subsequent adsorption of oxygen species on the SWCNT surface alter its electrical properties. The responses to the total dose and dose rate are investigated along with the sensing mechanism. The detector showed good sensitivity to γ ray and a capability to distinguish radiation dose rates ranging from 2.4 to 16.4 R/min.


Asunto(s)
Rayos gamma , Nanotubos de Carbono/química , Radiometría/métodos , Adsorción , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Microcomputadores , Ozono/química , Radiometría/instrumentación
4.
Pacing Clin Electrophysiol ; 40(2): 162-174, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-28000227

RESUMEN

BACKGROUND: The role of J-waves in the pathogenesis of ventricular fibrillation (VF) occurring in structurally normal hearts is important. METHODS: We evaluated 127 patients who received an implantable cardioverter-defibrillator (ICD) for Brugada syndrome (BS, n = 53), early repolarization syndrome (ERS, n = 24), and patients with unknown or deferred diagnosis (n = 50). Electrocardiography (ECG), clinical characteristics, and ICD data were analyzed. RESULTS: J-waves were found in 27/50 patients with VF of unknown/deferred diagnosis. The J-waves were reminiscent of those seen in BS or ERS, and this subgroup of patients was termed variants of ERS and BS (VEB). In 12 VEB patients, the J/ST/T-wave morphology was coved, although amplitudes were <0.2 mV. In 15 patients, noncoved-type J/ST/T-waves were present in the right precordial leads. In the remaining 23 patients, no J-waves were identified. VEB patients exhibited clinical characteristics similar to those of BS and ERS patients. Phenotypic transition and overlap were observed among patients with BS, ERS, and VEB. Twelve patients with BS had background inferolateral ER, while five ERS patients showed prominent right precordial J-waves. Patients with this transient phenotype overlap showed a significantly lower shock-free survival than the rest of the study patients. CONCLUSIONS: VEB patients demonstrate ECG phenotype similar to but distinct from those of BS and ERS. The spectral nature of J-wave morphology/distribution and phenotypic transition/overlap suggest a common pathophysiologic background in patients with VEB, BS, and ERS. Prognostic implication of these ECG variations requires further investigation.


Asunto(s)
Síndrome de Brugada/clasificación , Síndrome de Brugada/diagnóstico , Electrocardiografía/métodos , Infarto del Miocardio con Elevación del ST/clasificación , Infarto del Miocardio con Elevación del ST/diagnóstico , Diagnóstico Diferencial , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
5.
Sci Rep ; 6: 38389, 2016 12 06.
Artículo en Inglés | MEDLINE | ID: mdl-27922094

RESUMEN

Foldable organic memory on cellulose nanofibril paper with bendable and rollable characteristics is demonstrated by employing initiated chemical vapor deposition (iCVD) for polymerization of the resistive switching layer and inkjet printing of the electrode, where iCVD based on all-dry and room temperature process is very suitable for paper electronics. This memory exhibits a low operation voltage of 1.5 V enabling battery operation compared to previous reports and wide memory window. The memory performance is maintained after folding tests, showing high endurance. Furthermore, the quick and complete disposable nature demonstrated here is attractive for security applications. This work provides an effective platform for green, foldable and disposable electronics based on low cost and versatile materials.

6.
Nanoscale ; 8(16): 8878-86, 2016 Apr 28.
Artículo en Inglés | MEDLINE | ID: mdl-27071328

RESUMEN

Developing a well-defined nanostructure that can provide strong, reproducible, and stable SERS signals is quite important for the practical application of surface-enhanced Raman scattering (SERS) sensors. We report here a novel single nanowire (NW) on graphene (SNOG) structure as an efficient, reproducible, and stable SERS-active platform. Au NWs having a well-defined single-crystal geometry on a monolayer graphene-coated metal film can form a well-defined, continuous nanogap structure that provides extremely reproducible and stable SERS signals. The in-NW reproducibility was verified by 2-dimensional Raman mapping, and the NW-to-NW reproducibility was verified by the cumulative curves of 32 SERS spectra. The simulation also indicated that a highly regular, line-shaped hot spot formed between the Au NW and graphene. Furthermore, SNOG platforms showed improved photostability and long-term oxidation immunity. We anticipate that SNOG platforms will be appropriate for practical biological and chemical sensor applications that demand reproducible, stable, and strong signal production.

7.
ACS Nano ; 9(7): 7306-13, 2015 Jul 28.
Artículo en Inglés | MEDLINE | ID: mdl-26056735

RESUMEN

The memory for the Internet of Things (IoT) requires versatile characteristics such as flexibility, wearability, and stability in outdoor environments. Resistive random access memory (RRAM) to harness a simple structure and organic material with good flexibility can be an attractive candidate for IoT memory. However, its solution-oriented process and unclear switching mechanism are critical problems. Here we demonstrate iCVD polymer-intercalated RRAM (i-RRAM). i-RRAM exhibits robust flexibility and versatile wearability on any substrate. Stable operation of i-RRAM, even in water, is demonstrated, which is the first experimental presentation of water-resistant organic memory without any waterproof protection package. Moreover, the direct observation of a carbon filament is also reported for the first time using transmission electron microscopy, which puts an end to the controversy surrounding the switching mechanism. Therefore, reproducibility is feasible through comprehensive modeling. Furthermore, a carbon filament is superior to a metal filament in terms of the design window and selection of the electrode material. These results suggest an alternative to solve the critical issues of organic RRAM and an optimized memory type suitable for the IoT era.

8.
Nanoscale ; 6(14): 7799-804, 2014 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-24892839

RESUMEN

A mechanical and electrical transistor structure (METS) is proposed for effective voltage scaling. The sub-2 nm nanogap by atomic layer deposition (ALD) without stiction and the application of a dielectric with high-permittivity allowed the pull-in voltage of sub-2 V, showing the strength of the mechanical actuation that is hard to realize in a typical complementary metal-oxide-semiconductor (CMOS) transistor. The results are verified by simulation and interpreted by the numerical equation. Therefore the METS can pave a new way to make a breakthrough to overcome the limits of CMOS technology.

9.
Small ; 10(19): 3887-94, 2014 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-24912667

RESUMEN

Triboelectric nanogenerators with nature-replicated interface structures are presented. Effective contact areas of the triboelectric surfaces are largely enhanced because of the densely packed nano-in-micro hierarchical structures in nature. The enlarged contact area causes stronger triboelectric charge density, which results in output power increment. The interface engineering also allows the improved humidity resistance, which is an important parameter for the stable energy harvesting.


Asunto(s)
Materiales Biomiméticos , Suministros de Energía Eléctrica , Nanotecnología , Animales , Dimetilpolisiloxanos/química , Electroquímica , Electrodos , Diseño de Equipo , Hemípteros , Humanos , Humedad , Microscopía Electrónica de Rastreo , Oscilometría , Hojas de la Planta/metabolismo , Polímeros/química , Propiedades de Superficie , Temperatura , Alas de Animales/patología
10.
J Cardiovasc Electrophysiol ; 23(7): 757-63, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22353358

RESUMEN

INTRODUCTION: The circadian and seasonal patterns of ventricular tachyarrhythmia (VTA) in patients with early repolarization syndrome (ERS) have not been determined. We compared the timing of VTAs in patients with ERS and Brugada syndrome (BS). METHODS AND RESULTS: We enrolled patients with ERS (n = 14) and BS (n = 53) who underwent implantable cardioverter defibrillator (ICD) implantation. The timing of VTAs, including cardiac arrest and appropriate shocks, was determined. During follow up of 6.4 ± 3.6 years in the ERS group and 5.0 ± 3.3 years in the BS group, 5 of 14 (36%) ERS and 10 of 53 (19%) BS patients experienced appropriate shocks (P = 0.37). Cardiac arrest showed a trend of nocturnal distribution peaking from midnight to early morning (P = 0.14 in ERS, P = 0.16 in BS). Circadian distribution of appropriate shocks showed a significant nocturnal peak in patients with ERS (P < 0.0001) but a trend toward a nocturnal peak in patients with BS (P = 0.08). There were no seasonal differences in cardiac arrest in patients with ERS and BS. However, patients with ERS showed a seasonal peak in appropriate shocks from spring to summer (P < 0.0001). There was no significant seasonal peak in patients with BS. The timing of VTAs (cardiac arrest plus appropriate shock) showed significant nocturnal distributions in patients with ERS and BS (P < 0.01, respectively). A significant clustering of VTAs was noted from spring to summer (P < 0.01) in patients with ERS, but not in patients with BS (P = 0.42). CONCLUSIONS: Incidence of VTAs showed marked circadian variations with night-time peaks in patients with ERS and BS.


Asunto(s)
Arritmias Cardíacas/terapia , Síndrome de Brugada/terapia , Ritmo Circadiano , Muerte Súbita Cardíaca/prevención & control , Desfibriladores Implantables , Cardioversión Eléctrica/instrumentación , Estaciones del Año , Taquicardia Ventricular/terapia , Fibrilación Ventricular/terapia , Adulto , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/fisiopatología , Síndrome de Brugada/diagnóstico , Síndrome de Brugada/fisiopatología , Distribución de Chi-Cuadrado , Cardioversión Eléctrica/efectos adversos , Electrocardiografía , Técnicas Electrofisiológicas Cardíacas , Falla de Equipo , Femenino , Humanos , Masculino , Persona de Mediana Edad , República de Corea , Estudios Retrospectivos , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/fisiopatología , Factores de Tiempo , Resultado del Tratamiento , Fibrilación Ventricular/diagnóstico , Fibrilación Ventricular/fisiopatología
11.
J Nanosci Nanotechnol ; 9(2): 769-73, 2009 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-19441389

RESUMEN

In this work, we investigated the effect of surface treatment as release layer and adhesion promoter for UV-Nanoimprint lithography and measured the surface adhesion force by using tensile separation force of Instron equipment. Several Self-Assembled Monolayers (SAMs) of 3-Acryloxypropyl methyl dichlorosilane (APMDS) 3-Aminopropyl-triethoxysilane (APTS), and 3-Glycidoxypropyltrimethoxysilane (GPTS) as adhesion promoters and (1H,1H,2H,2H-perfluorooctyl)trichlorosilane (FOTS) as release layer were fabricated by vapor deposition method and were compared with oxygen plasma treatment. APMDS could strongly improve the adhesion force between UV-curable acrylate resin and silicon substrate because of strong covalent bonding. Finally, we could successfully fabricate various imprint patterns by using proper surface treatment of SAMs.

12.
J Cardiovasc Ultrasound ; 17(3): 99-101, 2009 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-20661324

RESUMEN

Intramyocardial hematoma is known to be associated with myocardial infarction, chest trauma, coronary artery bypass operation, and complication of percutaneous coronary intervention (PCI). We describe here a rare case of 50-year-old man with a huge right ventricular (RV) wall hematoma which was newly developed two hours after PCI. The patient was treated conservatively with a successful outcome. We discuss plausible mechanisms for the development of RV wall hematoma and treatment options for the case.

13.
Yonsei Med J ; 49(3): 507-8, 2008 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-18581604

RESUMEN

Pulmonary sequestration is an unusual malformation consisting of isolated nonfunctioning lung segments lacking communication with functional tracheobronchial trees. Systemic blood supply is commonly from the thoracic aorta, but arteries occasionally arise from other sites. We report a rare form of pulmonary sequestration with arterial supply from the right coronary artery.


Asunto(s)
Secuestro Broncopulmonar/patología , Anomalías de los Vasos Coronarios/patología , Anciano , Secuestro Broncopulmonar/diagnóstico por imagen , Angiografía Coronaria , Anomalías de los Vasos Coronarios/diagnóstico por imagen , Femenino , Humanos
14.
J Nanosci Nanotechnol ; 8(11): 5673-7, 2008 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-19198287

RESUMEN

Patterning flexible substrates in nano scale is an important and challenging issue in the fabrication of next-generation devices based on a non-silicon substrate. Step and Flash imprint lithography (S-FIL) which is a room temperature and low pressure process offers several important advantages, such as the use of a smaller and therefore cheaper stamp or the possibility of the overlay imprinting, as a transparent stamp is utilized. However, it is very difficult to perform S-FIL on a flexible substrate successfully due to the high waviness. The waviness of a flexible substrate is not a constant value in contrast to a rigid substrate. It depends on the imprint pressure applied onto the substrate. In this paper, in section two, the effect of the imprint pressure on the waviness of the surface of the flexible substrate is examined. It is proved that the waviness of the surface of the flexible substrate could not be reduced sufficiently to assure a successful imprint at low imprint pressures. In the third section, a method of patterning polymer substrates using ultra-violet nanoimprint lithography (UV-NIL) is presented. The method consists of two stages, stamping-based planarization and S-FIL. In stamping-based planarization, a planarization layer of transparent polymer is formed onto the flexible substrate. Waviness of the blank stamp (in this study, glass wafer) is transferred to the planarization layer. S-FIL is performed with the nanoimprint tool IMPRIO100 directly onto the planarization layer employing a 1 x 1 in. quartz stamp. Optical microscope and SEM images of the successfully imprinted patterns were also presented.


Asunto(s)
Cristalización/métodos , Nanoestructuras/química , Nanoestructuras/ultraestructura , Nanotecnología/métodos , Polímeros/química , Módulo de Elasticidad/efectos de la radiación , Sustancias Macromoleculares/química , Sustancias Macromoleculares/efectos de la radiación , Ensayo de Materiales , Conformación Molecular/efectos de la radiación , Nanoestructuras/efectos de la radiación , Tamaño de la Partícula , Polímeros/efectos de la radiación , Presión , Propiedades de Superficie/efectos de la radiación , Rayos Ultravioleta
15.
Bioelectromagnetics ; 24(4): 231-40, 2003 May.
Artículo en Inglés | MEDLINE | ID: mdl-12696083

RESUMEN

To identify possible effects of horizontally polarized magnetic field (MF) exposure on maintenance of pregnancy and embryo-fetal development, an MF exposure system was designed and constructed and 96 time-mated female Sprague-Dawley (SD) rats (24/group) received continuous exposure to 60 Hz MF at field strengths of 0 (sham control) and 5, 83.3, or 500 microT (50, 833, or 5000 mG). Dams received MF or sham exposures for 22 h/day on gestational day 6-20. MF was monitored continuously throughout the study. There were no evidences of maternal toxicity or developmental toxicity in any MF exposed groups. Mean maternal body weight, organ weights, and hematological and serum biochemical parameters in groups exposed to MF did not differ from those in sham control. No exposure related differences in fetal deaths, fetal body weight, and placental weight were observed between MF exposed groups and sham control. External, visceral, and skeletal examination of fetuses demonstrated no significant differences in the incidence of fetal malformations between MF exposed and sham control groups. In conclusion, exposure of pregnant rats to 60 Hz at MF strengths up to 500 microT during gestation day 6-20 did not produce any biologically significant effect in either dams or fetuses.


Asunto(s)
Anomalías Inducidas por Radiación/etiología , Peso Corporal/efectos de la radiación , Campos Electromagnéticos/efectos adversos , Desarrollo Embrionario y Fetal/efectos de la radiación , Exposición a Riesgos Ambientales/efectos adversos , Embarazo/efectos de la radiación , Animales , Instalación Eléctrica , Desarrollo Embrionario y Fetal/fisiología , Femenino , Tamaño de los Órganos/efectos de la radiación , Placenta/patología , Embarazo/fisiología , Resultado del Embarazo , Ratas , Ratas Sprague-Dawley , Reproducción/efectos de la radiación
16.
Mol Cells ; 16(3): 302-6, 2003 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-14744019

RESUMEN

Parvalbumin (PV) is found in the olfactory system, including the main olfactory bulb, and is thought to be one of the neuroactive substances in olfaction. Changes in PV immunoreactivity in the olfactory system during aging have not been examined. We investigated such changes in the main olfactory bulb (MOB) of the rat at postnatal month 1 (PM 1), PM 3, PM 6, PM 12 and PM 24. PV-IR neurons were almost completely restricted to the external plexiform layer. At PM 1 there were only a few PV-IR neurons; at PM 3, the number of PV-IR neurons was at its greatest but they were not well developed morphologically. At PM 6, the number of PV-IR neurons was similar to that at PM 3 and they had satellite somata with well-developed processes with many varicosities. By PM 12 the number of neurons and processes had declined, and by PM 24, they had fallen even further and the remaining processes had lost most of their varicosities. We conclude that age-related degeneration of PV-IR neurons in the MOB may reduce calcium buffering and affect olfactory function in senile species.


Asunto(s)
Envejecimiento/metabolismo , Neuronas/metabolismo , Bulbo Olfatorio/metabolismo , Parvalbúminas/metabolismo , Animales , Técnica del Anticuerpo Fluorescente , Neuronas/inmunología , Bulbo Olfatorio/inmunología , Parvalbúminas/inmunología , Ratas
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...