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1.
Phys Rev Lett ; 108(16): 166802, 2012 Apr 20.
Artículo en Inglés | MEDLINE | ID: mdl-22680748

RESUMEN

The two-dimensional electron gas at the interface between LaAlO(3) and SrTiO(3) has become one of the most fascinating and highly debated oxide systems of recent times. Here we propose that a one-dimensional electron gas can be engineered at the step edges of the LaAlO(3)/SrTiO(3) interface. These predictions are supported by first-principles calculations and electrostatic modeling which elucidate the origin of the one-dimensional electron gas as an electronic reconstruction to compensate a net surface charge in the step edge. The results suggest a novel route to increasing the functional density in these electronic interfaces.

2.
J Phys Condens Matter ; 23(30): 305002, 2011 Aug 03.
Artículo en Inglés | MEDLINE | ID: mdl-21709353

RESUMEN

We show the influence of pulsed laser deposition fluence on the transport properties of the LaAlO(3)/SrTiO(3) (LAO/STO) heterointerface. Structural characterization by x-ray diffraction and medium energy ion spectrometry enables us to deduce that the electronic behaviour is extremely sensitive to the stoichiometry of the LAO layer as well as the structural quality of the STO surface. An optimum balance of these two quantities is demonstrated for an intermediate laser fluence.

3.
J Phys Condens Matter ; 22(30): 302003, 2010 Aug 04.
Artículo en Inglés | MEDLINE | ID: mdl-21399332

RESUMEN

We report the observation of intrinsic exchange hardening in polycrystalline GdN thin films grown at room temperature by magnetron sputtering. We find, in addition to the ferromagnetic phase, that a fraction of GdN crystallizes in a structural polymorphic form which orders antiferromagnetically. The relative fraction of these two phases was controlled by varying the relative abundance of reactive species in the sputtering plasma by means of the sputtering power and N(2) partial pressure. An exchange bias of ∼ 30 Oe was observed at 10 K. The exchange coupling between the ferromagnetic and the antiferromagnetic phases resulted in an order of magnitude enhancement in the coercive field in these films.

4.
Phys Rev Lett ; 103(16): 166802, 2009 Oct 16.
Artículo en Inglés | MEDLINE | ID: mdl-19905715

RESUMEN

The thickness and origin of the free charge layer which forms at the LaAlO_{3}/SrTiO_{3} interface is still uncertain. By inserting Mn dopants at different distances from the interface we can locate the position of carriers within the SrTiO3 surface layers. We show that the majority of the carriers in fully-oxygenated samples are confined within 1 unit cell of the interface. This confirms the "polar-catastrophe" mechanism proposed for this system but the low mobility of these carriers demonstrates the need for improved materials for applications and a more complete understanding of the role of the minority of higher mobility carriers identified.

5.
Nanotechnology ; 18(49): 495708, 2007 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-20442489

RESUMEN

In spin valve type systems, one ferromagnetic electrode must be magnetically hard to act as a reference layer while the other electrode must be magnetically soft to act as a sensor or storage layer. This magnetic hard-soft architecture can usually be obtained by four different methods: the use of two ferromagnets with different coercive fields (here CoFe(2) and Ni(80)Fe(20)), the use of an underlayer enhancing the coercive field of one of the two ferromagnets (here Ta and Ru), the use of a ferromagnet coupled to a ferrimagnet or antiferromagnet (here NiO/CoFe(2) and CoFe(2)O(4)/CoFe(2)), or the use of an artificial antiferromagnet (here CoFe(2)/Ru/CoFe(2)). We show that at least the first and the third methods seem to work with pulsed laser deposition in the thermodynamic conditions used.

6.
AJR Am J Roentgenol ; 167(5): 1305-7, 1996 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-8911201

RESUMEN

OBJECTIVE: The purpose of this original report is to describe medial transposition of the common carotid arteries. This transposition may produce wide retropharyngeal soft tissues on lateral cervical radiographs. CONCLUSION: When common carotid arteries are transposed from their normal lateral positions into the retropharyngeal soft tissues, if vascular calcifications are present, this carotid abnormality is easily recognized on plain radiographs. Radiologists and clinical physicians should be aware that vascular transposition may be a benign cause of widening of the retropharyngeal soft tissues.


Asunto(s)
Arteria Carótida Común/anomalías , Cuello/diagnóstico por imagen , Faringe/diagnóstico por imagen , Anciano , Arteriosclerosis/diagnóstico por imagen , Calcinosis/diagnóstico por imagen , Enfermedades de las Arterias Carótidas/diagnóstico por imagen , Arteria Carótida Común/diagnóstico por imagen , Medios de Contraste , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tomografía Computarizada por Rayos X
7.
Clin Imaging ; 18(2): 99-100, 1994.
Artículo en Inglés | MEDLINE | ID: mdl-8033014

RESUMEN

An aortocoronary saphenous vein graft aneurysm was diagnosed with computed tomography and selective arteriography in a 79-year-old woman with a history of multiple coronary bypass graft surgeries. Aneurysms of saphenous vein grafts are rare complications of bypass surgery but need to be considered when evaluating bypass patients who present with a mediastinal or paracardiac mass.


Asunto(s)
Aneurisma/diagnóstico por imagen , Puente de Arteria Coronaria/métodos , Vena Safena/trasplante , Anciano , Aneurisma/etiología , Angiografía , Femenino , Humanos , Vena Safena/diagnóstico por imagen , Tomografía Computarizada por Rayos X
8.
Calcif Tissue Int ; 47(1): 18-23, 1990 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-2369687

RESUMEN

This study explores the effects of a calcium-deficient diet on patterns of bone remodeling, and examines regional differences in the amount of bone lost. Skeletally mature female rabbits (n = 6) were fed a calcium-deficient diet (0.10% Ca2+ and 0.50% P) for 14 weeks. A separate group of rabbits (n = 4) were fed a maintenance diet (1.2% Ca2+ and 0.45% P). Bone mineral content, serum calcium, and serum phosphorus were measured each week during the experimental period. Following sacrifice, the L3 vertebra, femoral head, proximal tibial metaphysis, and tibial midshaft were analyzed histomorphometrically. Rabbits had 20% less vertebral bone after only 14 weeks of a calcium-deficient diet. As in human postmenopausal osteoporosis, bone loss in calcium-deficient rabbits occurs in the trabecular bone of the lumbar spine before that in the trabecular bone of the lower extremity. Calcium-deficient diets alone do not lead to increased osteoid volume or thickness. Because bone loss is relatively rapid and because the pattern of loss is similar in some respects to that found in humans, adult rabbits may provide an attractive model of calcium deficiency osteoporosis in a skeletally mature mammal in which remodeling is predominant over modeling.


Asunto(s)
Desarrollo Óseo/fisiología , Calcio/deficiencia , Osteoporosis/fisiopatología , Animales , Peso Corporal/fisiología , Densidad Ósea/fisiología , Desarrollo Óseo/efectos de los fármacos , Huesos/análisis , Calcio/sangre , Calcio/farmacología , Dieta/efectos adversos , Modelos Animales de Enfermedad , Femenino , Minerales/análisis , Osteoporosis/etiología , Fósforo/sangre , Conejos , Factores de Tiempo
9.
J Pharmacol Exp Ther ; 196(2): 269-79, 1976 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-943520

RESUMEN

Rats drank solutions of narcotic analgesics as the only drinking fluid available in their cages. Relative to their daily water intake before the drug solutions were introduced, the rats drank more etonitazene solution, less methadone solution, and about the same volume of morphine, meperidine and levorphanol solution as water, although some rats would not drink the higher concentrations of morphine (1.0 mg/ml), levorphanol (1.0 mg/ml) and methadone (1.0 mg/ml). When naloxone (1.0 mg/kg) was administered after 12 days of drinking the drug solutions, the severity of the abstinence syndromes based on scoring of symptoms and on weight loss was morphine greater than or equal to etonitazine greater than levorphanol greater than meperidine greater than methadone. The animals showing the most severe syndrome after naloxone usually consumed more drug solution than usual during the next 24 hours, so that body weights were normal at the end of the 24-hour period. Nonprecipitated abstinence was also studied in these rats by replacing the drug solutions with water 3 to 5 days after the naloxone injection. Rats that had been drinking morphine, etonitazene and levorphanol lost weight for 2 or 3 days and then began to regain their lost weight. In contrast, rats which had been switched from methadone and meperidine solutions to water gained weight rapidly. Morphine and etonitazene drinkers which had been switched to water drank a lesser volume of water than they had been drinking of drug solution whereas some ex-methadone drinkers drank more water.


Asunto(s)
Administración Oral , Animales , Peso Corporal/efectos de los fármacos , Ritmo Circadiano , Ingestión de Líquidos , Humanos , Masculino , Morfina/sangre , Naloxona/farmacología , Antagonistas de Narcóticos/farmacología , Ratas , Síndrome de Abstinencia a Sustancias/inducido químicamente , Síndrome de Abstinencia a Sustancias/fisiopatología , Factores de Tiempo , Agua
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