10,854 research outputs found
Aharonov-Bohm effect in monolayer black phosphorus (phosphorene) nanorings
This work presents theoretical demonstration of Aharonov-Bohm (AB) effect in
monolayer phosphorene nanorings (PNR). Atomistic quantum transport simulations
of PNR are employed to investigate the impact of multiple modulation sources on
the sample conductance. In presence of a perpendicular magnetic field, we find
that the conductance of both armchair and zigzag PNR oscillate periodically in
a low-energy window as a manifestation of the AB effect. Our numerical results
have revealed a giant magnetoresistance (MR) in zigzag PNR (with a maximum
magnitude approaching two thousand percent). It is attributed to the AB effect
induced destructive interference phase in a wide energy range below the bottom
of the second subband. We also demonstrate that PNR conductance is highly
anisotropic, offering an additional way to modulate MR. The giant MR in PNR is
maintained at room temperature in the presence of thermal broadening effect.Comment: 7 pages, 7 figure
A tight linear chromatic bound for ()-free graphs
For two vertex disjoint graphs and , we use to denote the
graph with vertex set and edge set , and use
to denote the graph with vertex set and edge set
. A is the graph
. In this paper, we prove that if is a
()-free graph. This bound is tight when and ,
and improves the main result of Wang and Zhang. Also, this bound partially
generalizes some results of Prashant {\em et al.}.Comment: arXiv admin note: text overlap with arXiv:2308.05442,
arXiv:2307.1194
Effects of Cations and PH on Antimicrobial Activity of Thanatin and s-Thanatin against _Escherichia coli_ ATCC25922 and _B. subtilis_ ATCC 21332
Thanatin and s-thanatin were insect antimicrobial peptides which have shown potent antimicrobial activities on a variety of microbes. In order to investigate the effect of cations and pH on the activity of these peptides against Gram-negative bacteria and Gram-positive bacteria, the antimicrobial activities of both peptides were studied in increasing concentrations of monovalent cations (K^+^ and Na^+^), divalent cations (Ca^2+^ and Mg^2+^) and H^+^. The NCCLS broth microdilution method showed that both peptides were sensitive to the presence of cations. The divalent cations showed more antagonized effect on the activity against Gram-negative bacteria than the monovalent cations, since the two peptides lost the ability to inhibit bacterial growth at a very low concentration. In addition, the activities of both peptides tested were not significantly affected by pH. Comparing to studies of other antibacterial peptide activities, our data support a hypothesis that positive ions affect the sensitivity to cation peptides
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