31 research outputs found
Exotic electronic states in gradient-strained untwisted graphene bilayers
Many exotic electronic states were discovered in moire superlattices hosted
in twisted homo-bilayers in the past decade, including unconventional
superconductivity and correlated insulating states. However, it is technically
challenging to precisely and orderly stack two or more layers into certain
twisting angles. Here, we presented a theoretical strategy that introduces
moire superlattices in untwisted homo-bilayers by applying different in-plane
strains on the two layers of a graphene homo-bilayer, respectively. Our density
functional theory calculations indicate that the graphene bilayer exhibits
substantial out-of-plane corrugations that form a coloring-triangular structure
in each moire supercell under gradient in-plane strains. Such structure leads
to a set of kagome bands, namely one flat-band and, at least, one Dirac band,
developing along the M-K path after band-folding. For comparison, uniformly
applied in-plane strain only yields a nearly flat band within path K-G, which
is originated from local quantum confinement. These findings highlight the
gradient strain as a route to feasibly fabricate exotic electronic states in
untwisted flexible homo-bilayers.Comment: 15 pages, 4 figure
Intralayer Negative Poisson's Ratio in Two-Dimensional Black Arsenic by Strain Engineering
Negative Poisson's ratio as the anomalous characteristic generally exists in
artificial architectures, such as re-entrant and honeycomb structures. The
structures with negative Poisson's ratio have attracted intensive attention due
to their unique auxetic effect and many promising applications in shear
resistant and energy absorption fields. However, experimental observation of
negative Poisson's ratio in natural materials barely happened, although various
two-dimensional layered materials are predicted in theory. Herein, we report
the anisotropic Raman response and the intrinsic intralayer negative Poisson's
ratio of two-dimensional natural black arsenic (b-As) via strain engineering
strategy. The results were evident by the detailed Raman spectrum of b-As under
uniaxial strain together with density functional theory calculations. It is
found that b-As was softer along the armchair than zigzag direction. The
anisotropic mechanical features and van der Waals interactions play essential
roles in strain-dependent Raman shifts and negative Poisson's ratio in the
natural b-As along zigzag direction. This work may shed a light on the
mechanical properties and potential applications of two-dimensional puckered
materials.Comment: 23 pages, 4 figure
Evaluation of a novel saliva-based epidermal growth factor receptor mutation detection for lung cancer: A pilot study.
BackgroundThis article describes a pilot study evaluating a novel liquid biopsy system for non-small cell lung cancer (NSCLC) patients. The electric field-induced release and measurement (EFIRM) method utilizes an electrochemical biosensor for detecting oncogenic mutations in biofluids.MethodsSaliva and plasma of 17 patients were collected from three cancer centers prior to and after surgical resection. The EFIRM method was then applied to the collected samples to assay for exon 19 deletion and p.L858 mutations. EFIRM results were compared with cobas results of exon 19 deletion and p.L858 mutation detection in cancer tissues.ResultsThe EFIRM method was found to detect exon 19 deletion with an area under the curve (AUC) of 1.0 in both saliva and plasma samples in lung cancer patients. For L858R mutation detection, the AUC of saliva was 1.0, while the AUC of plasma was 0.98. Strong correlations were also found between presurgery and post-surgery samples for both saliva (0.86 for exon 19 and 0.98 for L858R) and plasma (0.73 for exon 19 and 0.94 for L858R).ConclusionOur study demonstrates the feasibility of utilizing EFIRM to rapidly, non-invasively, and conveniently detect epidermal growth factor receptor mutations in the saliva of patients with NSCLC, with results corresponding perfectly with the results of cobas tissue genotyping