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Nano Lett ; 19(12): 8526-8532, 2019 12 11.
Artigo em Inglês | MEDLINE | ID: mdl-31664847


In graphite crystals, layers of graphene reside in three equivalent, but distinct, stacking positions typically referred to as A, B, and C projections. The order in which the layers are stacked defines the electronic structure of the crystal, providing an exciting degree of freedom which can be exploited for designing graphitic materials with unusual properties including predicted high-temperature superconductivity and ferromagnetism. However, the lack of control of the stacking sequence limits most research to the stable ABA form of graphite. Here, we demonstrate a strategy to control the stacking order using van der Waals technology. To this end, we first visualize the distribution of stacking domains in graphite films and then perform directional encapsulation of ABC-rich graphite crystallites with hexagonal boron nitride (hBN). We found that hBN encapsulation, which is introduced parallel to the graphite zigzag edges, preserves ABC stacking, while encapsulation along the armchair edges transforms the stacking to ABA. The technique presented here should facilitate new research on the important properties of ABC graphite.

Nat Commun ; 10(1): 987, 2019 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-30804336


The original version of this Article contained an error in the spelling of the author Matthew Holwill, which was incorrectly given as Mathew Holwill. This has now been corrected in both the PDF and HTML versions of the Article.

Nat Commun ; 10(1): 230, 2019 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-30651554


Despite a rich choice of two-dimensional materials, which exists these days, heterostructures, both vertical (van der Waals) and in-plane, offer an unprecedented control over the properties and functionalities of the resulted structures. Thus, planar heterostructures allow p-n junctions between different two-dimensional semiconductors and graphene nanoribbons with well-defined edges; and vertical heterostructures resulted in the observation of superconductivity in purely carbon-based systems and realisation of vertical tunnelling transistors. Here we demonstrate simultaneous use of in-plane and van der Waals heterostructures to build vertical single electron tunnelling transistors. We grow graphene quantum dots inside the matrix of hexagonal boron nitride, which allows a dramatic reduction of the number of localised states along the perimeter of the quantum dots. The use of hexagonal boron nitride tunnel barriers as contacts to the graphene quantum dots make our transistors reproducible and not dependent on the localised states, opening even larger flexibility when designing future devices.

Ann Surg Oncol ; 16(3): 745-50, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19116753


INTRODUCTION: To determine the factors affecting the success of bedside talc slurry (TS) used for symptomatic treatment of patients with malignant pleural effusion (MPE). METHODS: Data of 113 effusions in 103 MPE patients treated between 1999 and 2007 were retrospectively evaluated for the study. The study group involved 73 patients whose follow-up information was available out of 81 patients treated by TS. Causes of MPE were lung cancer in 22 patients (30.1%) and breast carcinoma in 21 patients (28.8%). RESULTS: The success rate of TS was significantly higher if the time period between radiological diagnosis of effusion and administration of TS was less than 30 days (P= .02), or spontaneous expansion was attained after chest tube drainage (CTD) (P= .01). Success rate was higher for patients with daily drainage of less than 200 ml before TS than patients with more than 200 ml of daily drainage (P= .01). Dose of talc, either 4 g or above (P= .34), primary cause of MPE (P= .53), time to termination of CTD (P= .57), amount of drainage when CTD was terminated (P= .23), and time period between CTD and administration of TS (P= .20) did not show a statistically significant effect on the success of TS. CONCLUSION: In the treatment of malignant pleural effusion, patients with daily drainage of less than 200 ml before TS developed less recurrence than patients with daily drainage of more than 200 ml. Longer time period between the diagnosis of MPE and onset of CTD increased recurrence.

Antiperspirantes/uso terapêutico , Cuidados Paliativos , Derrame Pleural Maligno/terapia , Pleurodese/métodos , Talco/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/complicações , Neoplasias/terapia , Derrame Pleural Maligno/diagnóstico , Derrame Pleural Maligno/etiologia , Prognóstico , Estudos Retrospectivos , Fatores de Tempo , Resultado do Tratamento