Facile Synthesis of High Quality Graphene Nanoribbons

Graphene nanoribbons have attracted attention for their novel electronic and spin transport properties1-6, and because nanoribbons less than 10 nm wide have a band gap that can be used to make field effect transistors. However, producing nanoribbons of very high quality, or in high volumes, remains a challenge. Here, we show that pristine few-layer nanoribbons can be produced by unzipping mildly gas-phase oxidized multiwalled carbon nanotube using mechanical sonication in an organic solvent. The nanoribbons exhibit very high quality, with smooth edges (as seen by high-resolution transmission electron microscopy), low ratios of disorder to graphitic Raman bands, and the highest electrical conductance and mobility reported to date (up to 5e2/h and 1500 cm2/Vs for ribbons 10-20 nm in width). Further, at low temperature, the nanoribbons exhibit phase coherent transport and Fabry-Perot interference, suggesting minimal defects and edge roughness. The yield of nanoribbons was ~2% of the starting raw nanotube soot material, which was significantly higher than previous methods capable of producing high quality narrow nanoribbons1. The relatively high yield synthesis of pristine graphene nanoribbons will make these materials easily accessible for a wide range of fundamental and practical applications.Comment: Nature Nanotechnology in pres

Alpha-Linolenic Acid: Is It Essential to Cardiovascular Health?

There is a large body of scientific evidence that has been confirmed in randomized controlled trials indicating a cardioprotective effect for omega-3 fatty acids from fish. For alpha-linolenic acid (ALA), which is the omega-3 fatty acid from plants, the relation to cardiovascular health is less clear. We reviewed the recent literature on dietary ALA intake, ALA tissue concentrations, and cardiovascular health in humans. Short-term trials (6–12 weeks) in generally healthy participants mostly showed no or inconsistent effects of ALA intake (1.2–3.6 g/d) on blood lipids, low-density lipoprotein oxidation, lipoprotein(a), and apolipoproteins A-I and B. Studies of ALA in relation to inflammatory markers and glucose metabolism yielded conflicting results. With regard to clinical cardiovascular outcomes, there is observational evidence for a protective effect against nonfatal myocardial infarction. However, no protective associations were observed between ALA status and risk of heart failure, atrial fibrillation, and sudden death. Findings from long-term trials of ALA supplementation are awaited to answer the question whether food-based or higher doses of ALA could be important for cardiovascular health in cardiac patients and the general population

Alpha-Linolenic Acid Intake and 10-Year Incidence of Coronary Heart Disease and Stroke in 20,000 Middle-Aged Men and Women in The Netherlands

Background - Whether intake of alpha-linolenic acid (ALA), the plant-derived n-3 polyunsaturated fatty acid (PUFA), could prevent cardiovascular diseases is not yet clear. We examined the associations of ALA intake with 10-year incidence of coronary heart disease (CHD) and stroke in the Netherlands. Methods - Data were collected from a general population of 20,069 generally healthy men and women, aged 20 to 65 years. Habitual diet was assessed at baseline (1993–1997) with a validated 178-item food frequency questionnaire. Incidences of CHD and stroke were assessed through linkage with mortality and morbidity registers. Hazard ratios (HR) were calculated with multivariable Cox proportional hazards models, adjusted for age, gender, lifestyle, and dietary factors. Results - During 8–13 years of follow-up, we observed 280 incident CHD events (19% fatal) and 221 strokes (4% fatal). Intakes of energy-adjusted ALA in quintiles ranged from less than 1.0 g/d in the bottom quintile (Q1) to more than 1.9 g/d in the top quintile (Q5). ALA intake was not associated with incident CHD, with HRs varying between 0.89 and 1.01 (all p>0.05) in Q2–Q5 compared with the bottom quintile of ALA intake. For incident stroke, however, participants in Q2–Q5 had a 35–50% lower risk compared with the reference group. HRs were 0.65 (0.43–0.97), 0.49 (0.31–0.76), 0.53 (0.34–0.83), and 0.65 (0.41–1.04) for Q2–Q5 respectively. Conclusion - In this general Dutch population, ALA intake was not associated with incident CHD. The data suggested that a low intake of ALA may be a risk factor for incident stroke. These results warrant confirmation in other population-based studies and in trial

Problem and Pathological Gambling in a Sample of Casino Patrons

Relatively few studies have examined gambling problems among individuals in a casino setting. The current study sought to examine the prevalence of gambling problems among a sample of casino patrons and examine alcohol and tobacco use, health status, and quality of life by gambling problem status. To these ends, 176 casino patrons were recruited by going to a Southern California casino and requesting that they complete an anonymous survey. Results indicated the following lifetime rates for at-risk, problem, and pathological gambling: 29.2, 10.7, and 29.8%. Differences were found with regards to gambling behavior, and results indicated higher rates of smoking among individuals with gambling problems, but not higher rates of alcohol use. Self-rated quality of life was lower among pathological gamblers relative to non-problem gamblers, but did not differ from at-risk or problem gamblers. Although subject to some limitations, our data support the notion of higher frequency of gambling problems among casino patrons and may suggest the need for increased interventions for gambling problems on-site at casinos

Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons.

Published versio