Cooperative island growth of large-area single-crystal graphene on copper using chemical vapor deposition.

In this work we explore the kinetics of single-crystal graphene growth as a function of nucleation density. In addition to the standard methods for suppressing nucleation of graphene by pretreatment of Cu foils using oxidation, annealing, and reduction of the Cu foils prior to growth, we introduce a new method that further reduces the graphene nucleation density by interacting directly with the growth process at the onset of nucleation. The successive application of these two methods results in roughly 3 orders of magnitude reduction in graphene nucleation density.

Real-time optical diagnostics of graphene growth induced by pulsed chemical vapor deposition.

The kinetics and mechanisms of graphene growth on Ni films at 720-880 °C have been measured using fast pulses of acetylene and real-time optical diagnostics. In situ UV-Raman spectroscopy was used to unambiguously detect isothermal graphene growth at high temperatures, measure the growth kinetics with ∼1 s temporal resolution, and estimate the fractional precipitation upon cooldown. Optical reflectivity and videography provided much faster temporal resolution.

Role of hydrogen in chemical vapor deposition growth of large single-crystal graphene.

We show that graphene chemical vapor deposition growth on copper foil using methane as a carbon source is strongly affected by hydrogen, which appears to serve a dual role: an activator of the surface bound carbon that is necessary for monolayer growth and an etching reagent that controls the size and morphology of the graphene domains. The resulting growth rate for a fixed methane partial pressure has a maximum at hydrogen partial pressures 200-400 times that of methane. The morphology and size of the graphene domains, as well as the number of layers, change with hydrogen pressure from irregularly shaped incomplete bilayers to well-defined perfect single layer hexagons.

Forgiveness and interpersonal relationships: a Nepalese investigation.

The present study examined the practice of forgiveness in Nepal. A model relating collectivism and forgiveness was examined. Participants (N = 221) completed measures of collectivism, individualism, forgiveness, conciliatory behavior, and motivations for avoidance and revenge toward the offender.

Gender differences in self-construal: how generalizable are Western findings?

The authors used the Twenty Statements Test in 2 studies to investigate gender and country differences in the spontaneous self-descriptions of 811 college students from Hong Kong, India, Nepal, Nigeria, and Zimbabwe and 136 secondary school students from Taiwan and Hong Kong. The authors performed statistical analysis and found no significant gender differences in the percentage of responses classified as belonging to the idiocentric self in either study. However, the authors found significant Country effects in both studies for responses classified as representing the idiocentric self and some aspects of the collective self, and the authors found significant Country x Gender effects involving all 4 categories of the idiocentric self and the collective self for the college students.