35 research outputs found
Electronic transport in polycrystalline graphene
Most materials in available macroscopic quantities are polycrystalline.
Graphene, a recently discovered two-dimensional form of carbon with strong
potential for replacing silicon in future electronics, is no exception. There
is growing evidence of the polycrystalline nature of graphene samples obtained
using various techniques. Grain boundaries, intrinsic topological defects of
polycrystalline materials, are expected to dramatically alter the electronic
transport in graphene. Here, we develop a theory of charge carrier transmission
through grain boundaries composed of a periodic array of dislocations in
graphene based on the momentum conservation principle. Depending on the grain
boundary structure we find two distinct transport behaviours - either high
transparency, or perfect reflection of charge carriers over remarkably large
energy ranges. First-principles quantum transport calculations are used to
verify and further investigate this striking behaviour. Our study sheds light
on the transport properties of large-area graphene samples. Furthermore,
purposeful engineering of periodic grain boundaries with tunable transport gaps
would allow for controlling charge currents without the need of introducing
bulk band gaps in otherwise semimetallic graphene. The proposed approach can be
regarded as a means towards building practical graphene electronics.Comment: accepted in Nature Material
Allergic diseases in the elderly
Demographic distribution of the population is progressively changing with the proportion of elderly persons increasing in most societies. This entails that there is a need to evaluate the impact of common diseases, such as asthma and other allergic conditions, in this age segment. Frailty, comorbidities and polymedication are some of the factors that condition management in geriatric patients. The objective of this review is to highlight the characteristics of allergic diseases in older age groups, from the influence of immunosenescence, to particular clinical implications and management issues, such as drug interactions or age-related side effects
Road safety in developing countries - A South African perspective
Please help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected] Ingenieurswes
Land freight issues in South Africa.
Please help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected] En BestuurswetenskappeLogistie
Road use taxation and external costs in South Africa.
Ekonomiese En BestuurswetenskappeLogistiekPlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]
The effect of admixtures on the fresh and consolidated behaviour of ECC
Please help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected] Ingenieurswes
A randomised, double-blind placebo-controlled trial of ascorbic acid supplementation for the prevention of preterm labour
GesondheidswetenskappeMenslike VoedingPlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]