Graphene epitaxy by chemical vapor deposition on SiC.

We demonstrate the growth of high quality graphene layers by chemical vapor deposition (CVD) on insulating and conductive SiC substrates. This method provides key advantages over the well-developed epitaxial graphene growth by Si sublimation that has been known for decades. (1) CVD growth is much less sensitive to SiC surface defects resulting in high electron mobilities of ∼1800 cm(2)/(V s) and enables the controlled synthesis of a determined number of graphene layers with a defined doping level. The high quality of graphene is evidenced by a unique combination of angle-resolved photoemission spectroscopy, Raman spectroscopy, transport measurements, scanning tunneling microscopy and ellipsometry. Our measurements indicate that CVD grown graphene is under less compressive strain than its epitaxial counterpart and confirms the existence of an electronic energy band gap. These features are essential for future applications of graphene electronics based on wafer scale graphene growth.

SEM and Raman analysis of graphene on SiC(0001).

Graphene grown by a sublimation technique was studied by Scanning Electron Microscopy (SEM) and micro-Raman spectroscopy. The measurement area of a sample was marked and investigated using both systems, as a result of which SEM images were directly compared with Raman maps. In this work we show that a correlative analysis of Energy Selective Backscattered electrons detector (EsB), In-Lens figures and Raman maps of shape and intensity of the 2D band is adequate to determine graphene layer thickness with the precision of SEM and reliability of Raman spectroscopy.

Treatment of X-linked hereditary nephritis in Samoyed dogs with angiotensin converting enzyme (ACE) inhibitor.

X-linked hereditary nephritis (HN) in Samoyed dogs is a model for human HN (Alport's syndrome). Angiotensin converting enzyme (ACE) inhibitors have been shown to slow the progression of renal disease in animal models and human patients. To determine the effect of ACE inhibitor treatment on X-linked HN in Samoyed dogs, a group of affected and a group of normal males were each randomly divided into two subgroups, which were either treated with an ACE inhibitor or left untreated. ACE inhibitor treatment caused significant increases (P < 0.05) in plasma renin activity in normal and affected dogs, confirming its effectiveness, but did not lower systemic blood pressure. Three of four affected treated dogs had improved weight gains and, overall, treated dogs survived 1.36 times longer than affected untreated dogs (P < 0.05). ACE inhibitor treatment of affected dogs significantly delayed (P < 0.05) the onset of an increase in serum creatinine concentration, tended to delay the decline of glomerular filtration rate and effective renal plasma flow (ERPF), significantly improved (P < 0.05) the ERPF at 110-154 days of age, and significantly slowed (P < 0.01) the rate of increase of proteinuria. Affected treated dogs showed a significant (P < 0.05) transient reduction in glomerular basement membrane splitting. Thus, ACE inhibitor treatment of Samoyed dogs with X-linked HN produced beneficial effects with respect to renal function, renal structure, and survival.

Comparison of direct and indirect blood pressure measurements in anesthetized dogs.

The precision and accuracy of an indirect oscillometric blood pressure measurement technique (Dinamap 8100) was assessed in 11 anesthetized Beagle dogs weighing 8 to 11.5 kg. Direct blood pressure measurements were made by catheterization of the lingual artery, and simultaneous indirect measurements were determined by placing a cuff over the median artery (midradial area). Blood pressure measurements at 2 different planes of anesthesia (light and deep) were recorded in triplicate. At a light plane of anesthesia, the Dinamap 8100 underestimated diastolic and mean arterial pressure, and at a deep anesthetic plane overestimated systolic pressure. The indirect technique had good repeatability of systolic pressures. Regression analysis for the 2 techniques showed excellent correlation (r = 0.93). The results indicate that the indirect oscillometric blood pressure measurement technique provides a good estimate of systolic, diastolic, and mean arterial pressure in dogs weighing 8-11.5 kg.