9 research outputs found
Alloyed surfaces: New substrates for graphene growth
We report a systematic ab-initio density functional theory investigation
of Ni(111) surface alloyed with elements of group IV (Si, Ge and Sn),
demonstrating the possibility to use it to grow high quality graphene.
Ni(111) surface represents an ideal substrate for graphene, due to its
catalytic properties and perfect matching with the graphene lattice
constant. However, Dirac bands of graphene growth on Ni(111) are
completely destroyed due to the strong hybridization between carbon p(z)
and Ni d orbitals. Group IV atoms, namely Si, Ge and Sn, once deposited
on Ni(111) surface, form an ordered alloyed surface with root 3 x root
3-R30 degrees reconstruction. We demonstrate that, at variance with the
pure Ni(111) surface, alloyed surfaces effectively decouple graphene
from the substrate, resulting untrained due to the nearly perfect
lattice matching and preserves linear Dirac bands without the strong
hybridization with Ni d states. The proposed surfaces can be prepared
before graphene growth without resorting on post-growth processes which
necessarily alter the electronic and structural properties of graphene.
(C) 2017 Elsevier B.V. All rights reserved
Detection of Antibody to Avian Influenza A (H5N1) Virus in Human Serum by Using a Combination of Serologic Assays
Epidemiology, Clinical Presentation, Laboratory Diagnosis, Antimicrobial Resistance, and Antimicrobial Management of Invasive Salmonella Infections.
Salmonella enterica infections are common causes of bloodstream infection in low-resource areas, where they may be difficult to distinguish from other febrile illnesses and may be associated with a high case fatality ratio. Microbiologic culture of blood or bone marrow remains the mainstay of laboratory diagnosis. Antimicrobial resistance has emerged in Salmonella enterica, initially to the traditional first-line drugs chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole. Decreased fluoroquinolone susceptibility and then fluoroquinolone resistance have developed in association with chromosomal mutations in the quinolone resistance-determining region of genes encoding DNA gyrase and topoisomerase IV and also by plasmid-mediated resistance mechanisms. Resistance to extended-spectrum cephalosporins has occurred more often in nontyphoidal than in typhoidal Salmonella strains. Azithromycin is effective for the management of uncomplicated typhoid fever and may serve as an alternative oral drug in areas where fluoroquinolone resistance is common. In 2013, CLSI lowered the ciprofloxacin susceptibility breakpoints to account for accumulating clinical, microbiologic, and pharmacokinetic-pharmacodynamic data suggesting that revision was needed for contemporary invasive Salmonella infections. Newly established CLSI guidelines for azithromycin and Salmonella enterica serovar Typhi were published in CLSI document M100 in 2015