96 research outputs found
Tunable Multifunctional Topological Insulators in Ternary Heusler Compounds
Recently the Quantum Spin Hall effect (QSH) was theoretically predicted and
experimentally realized in a quantum wells based on binary semiconductor
HgTe[1-3]. QSH state and topological insulators are the new states of quantum
matter interesting both for fundamental condensed matter physics and material
science[1-11]. Many of Heusler compounds with C1b structure are ternary
semiconductors which are structurally and electronically related to the binary
semiconductors. The diversity of Heusler materials opens wide possibilities for
tuning the band gap and setting the desired band inversion by choosing
compounds with appropriate hybridization strength (by lattice parameter) and
the magnitude of spin-orbit coupling (by the atomic charge). Based on the
first-principle calculations we demonstrate that around fifty Heusler compounds
show the band inversion similar to HgTe. The topological state in these
zero-gap semiconductors can be created by applying strain or by designing an
appropriate quantum well structure, similar to the case of HgTe. Many of these
ternary zero-gap semiconductors (LnAuPb, LnPdBi, LnPtSb and LnPtBi) contain the
rare earth element Ln which can realize additional properties ranging from
superconductivity (e. g. LaPtBi[12]) to magnetism (e. g. GdPtBi[13]) and
heavy-fermion behavior (e. g. YbPtBi[14]). These properties can open new
research directions in realizing the quantized anomalous Hall effect and
topological superconductors.Comment: 20 pages, 5 figure
Multipotent adult progenitor cells sustain function of ischemic limbs in mice
Despite progress in cardiovascular research, a cure for peripheral vascular disease has not been found. We compared
the vascularization and tissue regeneration potential of murine and human undifferentiated multipotent
adult progenitor cells (mMAPC-U and hMAPC-U), murine MAPC-derived vascular progenitors (mMAPC-VP),
and unselected murine BM cells (mBMCs) in mice with moderate limb ischemia, reminiscent of intermittent
claudication in human patients. mMAPC-U durably restored blood flow and muscle function and stimulated
muscle regeneration, by direct and trophic contribution to vascular and skeletal muscle growth. This was in
contrast to mBMCs and mMAPC-VP, which did not affect muscle regeneration and provided only limited and
transient improvement. Moreover, mBMCs participated in a sustained inflammatory response in the lower
limb, associated with progressive deterioration in muscle function. Importantly, mMAPC-U and hMAPC-U also
remedied vascular and muscular deficiency in severe limb ischemia, representative of critical limb ischemia in
humans. Thus, unlike BMCs or vascular-committed progenitors, undifferentiated multipotent adult progenitor
cells offer the potential to durably repair ischemic damage in peripheral vascular disease patients
Diagnostic Performance of Diffusion-weighted Magnetic Resonance Imaging in Bone Malignancy Evidence From a Meta-Analysis
Current state-of-the-art nuclear medicine imaging methods (such as PET/CT or bone scintigraphy) may have insufficient sensitivity for predicting bone tumor, and substantial exposure to ionizing radiation is associated with the risk of secondary cancer development. Diffusion-weighted MRI (DW-MRI) is radiation free and requires no intravenous contrast media, and hence is more suitable for population groups that are vulnerable to ionizing radiation and/or impaired renal functions. This meta-analysis was conducted to investigate whether whole-body DW-MRI is a viable means in differentiating bone malignancy. Medline and Embase databases were searched from their inception to May 2015 without language restriction for studies evaluating DW-MRI for detection of bone lesions. Methodological quality was assessed by the quality assessment of diagnostic studies (QUADAS-2) instrument. Sensitivities, specificities, diagnostic odds ratio (DOR), and areas under the curve (AUC) were used as measures of the diagnostic accuracy. We combined the effects by using the random-effects mode. Potential threshold effects and publication bias were investigated. We included data from 32 studies with 1507 patients. The pooled sensitivity, specificity, and AUC were 0.95 (95% CI, 0.90–0.97), 0.92 (95% CI, 0.88–0.95), and 0.98 on a per-patient basis, and they were 0.91 (95% CI, 0.87–0.94), 0.94 (95% CI, 0.90–0.96), and 0.97 on a per-lesion basis. In subgroup analysis, there is no statistical significance found in the sensitivity and specificity of using DWI only and DWI combined with other morphological or functional imaging sequence in both basis (P > 0.05). A b value of 750 to 1000 s/mm(2) enables higher AUC and DOR for whole-body imaging purpose when compared with other values in both basis either (P < 0.01). The ROC space did not show a curvilinear trend of points and a threshold effect was not observed. According to the Deek's plots, there was no publication bias on both basis. Our results support the use of DWI as an effective means for distinguishing malignant bone lesions; however, various imaging parameters need to be standardized prior to its broad use in clinical practice
Tilted microstrip phased arrays with improved electromagnetic decoupling for ultrahigh-field magnetic resonance imaging
Copyright © 2014 Wolters Kluwer Health / Lippincott Williams & Wilkins.One of the technical challenges in designing a dedicated transceiver radio frequency (RF) array for MR imaging in humans at ultrahigh magnetic fields is how to effectively decouple th
Preparation of Graphene Sponge Coated Iron Electrode for the Electrolytic Decoloration of Methylene Blue
Electrolysis is a widely adopted technology in water treatment, while the major challenge focuses on developing better electrode materials. In this study, we reported that the hydrothermal coating of graphene sponge (GS) on Fe electrode (GS-Fe electrode) could significantly improve the decoloration performance of Fe electrode. The decoloration kinetics constant of GS-Fe electrode was five times of that of Fe electrode at the same current density. Mechanistically, the electrolytic oxidation of MB was via indirect pathway, where Cl- was oxidized into ClO- for the oxidation of other substances. Moreover, the performance of GS-Fe electrode remained nearly unchanged in the recycling evaluations. The implication to the applications of GS-Fe electrode in water treatment is discussed
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