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Qian Gu

Publications and source records attributed to Qian Gu.

5 recordsLinked to original sources

Germanium telluride nanowires and nanohelices with memory-switching behavior.

We report the synthesis of single-crystalline GeTe nanowires (NWs) and nanohelices (NHs) using a vapor transport method assisted by metal catalysts. The NWs have typical diameters of 65 +/- 20 nm and lengths reaching up to 50 mum, while NHs have an average helix diameter of 135 +/- 30 nm, with widely varying pitches. Electron microscopy and diffraction measurements show that these NWs and NHs are single crystalline and exhibit a rhombohedral structure. The devices incorporating individual GeTe NWs exhibit nonvolatile resistance changes associated with voltage-driven crystalline-amorphous transitions, suggesting that these NWs can be the basis of an electrically driven nonvolatile memory.

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[Glucose metabolism status and angiographic features of coronary artery in patients undergoing their first coronary angiography: study of 553 cases].

OBJECTIVE: To investigate the correlation between glucose metabolism status and coronary artery lesion in the patients undergoing their first coronary angiography (CAG). METHODS: Oral glucose tolerance test (OGTT) and CAG were performed in 553 patients with suspected or confirmed coronary artery disease (CAD), aged 60.1 +/- 9.7. The anthroposomatologic parameters, blood pressure, HbA1c, and lipid profile of these patients were collected. Their glucose metabolism status was assessed based on the WHO diagnostic criteria of diabetes mellitus 1999 and American Heart Association's grading standards for evaluating coronary artery stenosis and Gensini score were applied to analyze the coronary artery lesion. According to the CAG results the patients were divided into CAD group and non-CAD group and then the glucose metabolic characteristics in both groups were analyzed by comparison based on the glycometabolic status. The patients were also grouped into diabetic and non-diabetic groups and the coronary artery angiographic features in both groups were compared. RESULTS: Among the 533 patients 277 (50.1%) had normal OGTT, 127 (23.0%) were diagnosed as with impaired glucose regulation, 61 (11%) were newly diagnosed as with type 2 diabetes mellitus, and the other 88 patients (15.9%) were already known diabetics. The prevalence of abnormal glycometabolism in the CAD group was 56.4%, significantly higher than that in the non-CAD group (34.5%, P < 0.05). The prevalence of multiple branches involvement in the diabetic group was 63.8%, significantly higher than that of the non-diabetic group (44.1%, P < 0.05), and the Gensini score in the diabetic group was 15 (30.5), significantly higher than that of the [20 (27), P < 0.05]. CONCLUSION: Abnormal glycometabolism is common in the population undergoing coronary angiography. Both the prevalence of multiple branches involvement and the degree of stenosis of coronary in the diabetics are higher than that in those without diabetes.

Aged↗

Strain-induced self organization of metal-insulator domains in single-crystalline VO2 nanobeams.

We investigated the effect of substrate-induced strain on the metal-insulator transition (MIT) in single-crystalline VO(2) nanobeams. A simple nanobeam-substrate adhesion leads to uniaxial strain along the nanobeam length because of the nanobeam's unique morphology. The strain changes the relative stability of the metal (M) and insulator (I) phases and leads to spontaneous formation of periodic, alternating M-I domain patterns during the MIT. The spatial periodicity of the M-I domains can be modified by changing the nanobeam thickness and the Young's modulus of the substrate.

Crystallization↗

Single-crystalline vanadium dioxide nanowires with rectangular cross sections.

We report the synthesis of single-crystalline VO2 nanowires with rectangular cross sections using a vapor transport method. These nanowires have typical diameters of 60 (+/-30) nm and lengths up to >10 mum. Electron microscopy and diffraction measurements show that the VO2 nanowires are single crystalline and exhibit a monoclinic structure. Moreover, they preferentially grow along the [100] direction and are bounded by the (01) and (011) facets. These VO2 nanowires should provide promising materials for fundamental investigations of nanoscale metal-insulator transitions.

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Synthesis of single-crystalline perovskite nanorods composed of barium titanate and strontium titanate.

We report the solution-based synthesis of single-crystalline nanorods composed of barium titanate (BaTiO3) and strontium titanate (SrTiO3), which yields well-isolated nanorods with diameters ranging from 5 to 60 nm and lengths reaching up to >10 mum. Electron microscopy and diffraction measurements show that these nanorods are composed of single-crystalline cubic perovskite BaTiO3 and SrTiO3 with a principal axis of the unit cell preferentially aligned along the wire length. These BaTiO3 and SrTiO3 nanorods should provide promising materials for fundamental investigations on nanoscale ferroelectricity, piezoelectricity, and paraelectricity.

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