4,858 research outputs found
Noncollinearity-modulated electronic properties of the monolayer CrI
Introducing noncollinear magnetization into a monolayer CrI is proposed
to be an effective approach to modulate the local electronic properties of the
two-dimensional (2D) magnetic material. Using first-principles calculation, we
illustrate that both the conduction and valence bands in the monolayer CrI
are lowered down by spin spiral states. The distinct electronic structure of
the monolayer noncollinear CrI can be applied in nanoscale functional
devices. As a proof of concept, we show that a magnetic domain wall can form a
one-dimensional conducting channel in the 2D semiconductor via proper gating.
Other possible applications such as electron-hole separation and identical
quantum dots are also discussed
Protective effect of ischemic postconditioning on lung ischemia-reperfusion injury in rats and the role of heme oxygenase-1
ObjectiveTo investigate the effect of ischemic postconditioning (IPO) on acute lung ischemia-reperfusion (I/R) injury and the protein expression of haeme oxygenase-1 (HO-1), a cytoprotective defense against oxidative injury.MethodsAfter being anesthetized with chloralhydrate, forty-eight healthy SD rats were randomly divided into 6 groups (8 in each): sham operation group (S group); I/R group: left lung hilum was clamped for 40 minutes followed by 105 minutes of reperfusion; IPO group: left lung hilum was clamped for 40 minutes and postconditioned by 3 cycles of 30 seconds of reperfusion and 30 seconds of reocclusion; Hemin (HM)+ I/R group: hemin, an inducer of HO-1 was injected intraperitoneally at 40 μmol·kg−1 ·day−1 for two consecutive days prior to 40 minutes clamping of left lung hilum; ZnPPIX+IPO group: zinc protoporphyrin IX, an inhibitor of HO-1 was injected intraperitoneally at 20 mg·kg−1 24 hours prior to 40 minutes clamping of left lung hilum; and HM+S group: H M was administered as in the HM+I/R group without inducing lung I/R. Arterial partial pressure of oxygen (PaO2) and malondialdehyde (MDA) content in serum were assessed. The left lung was removed for determination of wet/dry lung weight ratio and expression of HO-1 protein by immuno-his-tochemical technique and for light microscopic examination.ResultsThe PaO2 was significantly lower in all the experimental groups compared with sham group (90 mm Hg ± 11 mm Hg). However, the values of PaO2 in IPO (81 mm Hg ± 7 mm Hg) and HM+I/R (80 mm Hg ± 9 mm Hg) were higher than that in I/R (63 mm Hg ± 9 mm Hg) and ZnPPIX+IPO (65 mm Hg±8 mm Hg) groups (P<0.01). The protein expression of HO-1 in lung tissue was significantly increased in I/R group compared with S group (P<0.01). While the HO-1 protein expression was higher in IPO and HM+I/R groups as compared with I/R group (P<0.05, P<0.01). The lung wet/dry (W/D) weight ratio and MDA content in serum were significantly increased in I/R group as compared with S or HM+S groups (P<0.01), accompanied by severe lung tissue histological damage, which was attenuated either by IPO or by HM pretreatment (P<0.01, IPO or HM+I/R vs. I/R). The protective effect of IPO was abolished by ZnPPIX.ConclusionIschemic postconditioning can attenuate the lung ischemia-reperfusion injury through upregulating the protein expression of HO-1 that leads to reduced post-ischemic oxidative damage
Ginsenoside Rb1 Preconditioning Enhances eNOS Expression and Attenuates Myocardial Ischemia/Reperfusion Injury in Diabetic Rats
Diabetes mellitus is associated with decreased NO bioavailability in the myocardium. Ginsenoside Rb1 has been shown to confer cardioprotection against ischemia reperfusion injury. The aim of this study was to investigate whether Ginsenoside Rb1 exerts cardioprotective effects during myocardial ischemia-reperfusion in diabetic rats and whether this effect is related to increase the production of NO via enhancing eNOS expression in the myocardium. The myocardial I/R injury were induced by occluding the left anterior descending artery for 30 min followed by 120 min reperfusion. An eNOS inhibitor L-NAME or Rb1 were respectively administered 25 min or 10 min before inducing ischemia. Ginsenoside Rb1 preconditioning reduced myocardial infarct size when compared with I/R group. Ginsenoside Rb1 induced myocardial protection was accompanied with increased eNOS expression and NO concentration and reduced plasma CK and LDH (P < 0.05). Moreover, the myocardial oxidative stress and tissue histological damage was attenuated by Ginsenoside Rb1 (P < 0.05). L-NAME abolished the protective effects of Ginsenoside Rb1. It is concluded that Ginsenoside Rb1 protects against myocardium ischemia/reperfusion injury in diabetic rat by enhancing the expression of eNOS and increasing the content of NO as well as inhibiting oxidative stress
Schr\"odinger-Heisenberg Variational Quantum Algorithms
Recent breakthroughs have opened the possibility to intermediate-scale
quantum computing with tens to hundreds of qubits, and shown the potential for
solving classical challenging problems, such as in chemistry and condensed
matter physics. However, the extremely high accuracy needed to surpass
classical computers poses a critical demand to the circuit depth, which is
severely limited by the non-negligible gate infidelity, currently around
0.1-1%. Here, by incorporating a virtual Heisenberg circuit, which acts
effectively on the measurement observables, to a real shallow Schr\"odinger
circuit, which is implemented realistically on the quantum hardware, we propose
a paradigm of Schr\"odinger-Heisenberg variational quantum algorithms to
resolve this problem. We choose a Clifford virtual circuit, whose effect on the
Hamiltonian can be efficiently and classically implemented according to the
Gottesman-Knill theorem. Yet, it greatly enlarges the state expressivity,
realizing much larger unitary t-designs. Our method enables accurate quantum
simulation and computation that otherwise is only achievable with much deeper
and more accurate circuits conventionally. This has been verified in our
numerical experiments for a better approximation of random states and a
higher-fidelity solution to the ground state energy of the XXZ model. Together
with effective quantum error mitigation, our work paves the way for realizing
accurate quantum computing algorithms with near-term quantum devices.Comment: We propose a framework of virtual Heisenberg-circuits-enhanced
variational quantum algorithms, which can noiselessly increase the effective
circuit depth to enlarge the quantum circuit expressivity and find
high-fidelity ground state
A Novel Image Segmentation Algorithm Based on Graph Cut Optimization Problem
Image segmentation, a fundamental task in computer vision, has been widely used in recent years in many fields. Dealing with the graph cut optimization problem obtains the image segmentation results. In this study, a novel algorithm with weighted graphs was constructed to solve the image segmentation problem through minimization of an energy function. A binary vector of the segmentation label was defined to describe both the foreground and the background of an image. To demonstrate the effectiveness of our proposed method, four various types of images were used to construct a series of experiments. Experimental results indicate that compared with other methods, the proposed algorithm can effectively promote the quality of image segmentation under three performance evaluation metrics, namely, misclassification error rate, rate of the number of background pixels, and the ratio of the number of wrongly classified foreground pixels
Protective effect of ginsenoside Rb1 against intestinal ischemia-reperfusion induced acute renal injury in mice
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