Band gap engineering of chemical vapor deposited graphene by in situ BN doping.

Band gap opening and engineering is one of the high priority goals in the development of graphene electronics. Here, we report on the opening and scaling of band gap in BN doped graphene (BNG) films grown by low-pressure chemical vapor deposition method. High resolution transmission electron microscopy is employed to resolve the graphene and h-BN domain formation in great detail. X-ray photoelectron, micro-Raman, and UV-vis spectroscopy studies revealed a distinct structural and phase evolution in BNG films at low BN concentration. Synchrotron radiation based XAS-XES measurements concluded a gap opening in BNG films, which is also confirmed by field effect transistor measurements. For the first time, a significant band gap as high as 600 meV is observed for low BN concentrations and is attributed to the opening of the π-π* band gap of graphene due to isoelectronic BN doping. As-grown films exhibit structural evolution from homogeneously dispersed small BN clusters to large sized BN domains with embedded diminutive graphene domains. The evolution is described in terms of competitive growth among h-BN and graphene domains with increasing BN concentration. The present results pave way for the development of band gap engineered BN doped graphene-based devices.

Acetylcysteine for prevention of acute deterioration of renal function following elective coronary angiography and intervention: a randomized controlled trial.

CONTEXT: The antioxidant acetylcysteine prevents acute contrast nephrotoxicity in patients with impaired renal function who undergo computed tomography scanning. However, its role in coronary angiography is unclear. OBJECTIVE: To determine whether oral acetylcysteine prevents acute deterioration in renal function in patients with moderate renal insufficiency who undergo elective coronary angiography. DESIGN AND SETTING: Prospective, randomized, double-blind, placebo-controlled trial conducted from May 2000 to December 2001 at the Grantham Hospital at the University of Hong Kong. PARTICIPANTS: Two hundred Chinese patients aged mean (SD) 68 (6.5) years with stable moderate renal insufficiency (creatinine clearance <60 mL/min [1.00 mL/s]) who were undergoing elective coronary angiography with or without intervention. INTERVENTION: Participants were randomly assigned to receive oral acetylcysteine(600 mg twice per day; n = 102) or matching placebo tablets (n = 98) on the day before and the day of angiography. All patients received low-osmolality contrast agent. MAIN OUTCOME MEASURES: Occurrence of more than a 25% increase in serum creatinine level within 48 hours after contrast administration; change in creatinine clearance and serum creatinine level. RESULTS: Twelve control patients (12%) and 4 acetylcysteine patients (4%) developed a more than 25% increase in serum creatinine level within 48 hours after contrast administration (relative risk, 0.32; 95% confidence interval [CI], 0.10-0.96; P =.03). Serum creatinine was lower in the acetylcysteine group (1.22 mg/dL [107.8 micromol/L]; 95% CI, 1.11-1.33 mg/dL vs 1.38 mg/dL [122.9 micromol/L]; 95% CI, 1.27-1.49 mg/dL; P =.006) during the first 48 hours after angiography. Acetylcysteine treatment significantly increased creatinine clearance from 44.8 mL/min (0.75 mL/s) (95% CI, 42.7-47.6 mL/min) to 58.9 mL/min (0.98 mL/s) (95% CI, 55.6-62.3 mL/min) 2 days after the contrast administration (P<.001). The increase was not significant in the control group (from 42.1 to 44.1 mL/min [0.70 to 0.74 mL/s]; P =.15). The benefit of acetylcysteine was consistent among various patient subgroups and persistent for at least 7 days. There were no major treatment-related adverse events. CONCLUSION: Acetylcysteine protects patients with moderate chronic renal insufficiency from contrast-induced deterioration in renal function after coronary angiographic procedures, with minimal adverse effects and at a low cost.

Successful rotational atherectomy and stenting in a situs inversus patient.

We describe a case of successful high-speed rotational atherectomy and stenting of a long calcified lesion in a patient with dextrocardia and situs inversus.

Long-term survival of quiescent left atrial myxoma in an elderly patient.

Left atrial myxoma, if left untreated, is inexorably progressive and usually fatal. The classical management of this disease is prompt surgical removal. However, there may be exceptions to this traditional dogma. The authors report an 85-year-old man who presented with features of chronic obstructive airway disease and congestive heart failure 15 years previously. Auscultation of the heart showed a pansystolic murmur. Two-dimensional echocardiography revealed a nonobstructive, calcified, and well circumscribed mass in the left atrium, with a pedicle attached to the interatrial septum. Because the patient refused high-risk cardiac surgery related to his comorbidity, he was managed medically with a bronchodilator, diuretics, and digoxin. There have been no features of embolism or intracardiac obstruction, and serial echocardiography demonstrates no disease progression over this long period of time. This case illustrates that calcified left atrial myxoma may exhibit a quiescent phase. Tumor calcification, slow growth potential, and the absence of intracardiac obstruction may correlate with a better outcome in the elderly patient.