Effects of Finite Deformed Length in Carbon Nanotubes

The effect of finite deformed length is demonstrated by squashing an armchair (10,10) single-walled carbon nanotube with two finite tips. Only when the deformed length is long enough, an effectual metal-semiconductor-metal heterojunction can be formed in the metallic tube. The effect of finite deformed length is explained by the quantum tunnelling effect. Furthermore, some conceptual designs of nanoscale devices are proposed from the metal-semiconductor-metal heterojunction.Comment: 4 pages, 4 figure

Clinical experience of phacoemulsification for cataract patients with angle-closure glaucoma in 29 cases

AIM: To observe the clinical effect of phacoemulsification with foldable intraocular lens implantation on cataract with angle-closure glaucoma. <p>METHODS: Twenty-nine cases(29 eyes)of angle-closure glaucoma with cataract underwent phacoemulsification with foldable intraocular lens implantation, and the data of visual acuity, intraocular pressure, gonioscopy and complications after operation were statistically analyzed.<p>RESULTS:Postoperatively, 28 eyes(96.5%)visual acuity were improved. Intraocular pressure of 25 eyes(86.2%)were maintained at a normal level without any IOP lowering drug, intraocular pressure of 3 eyes(10.3%)were controlled by IOP lowering eye drops, intraocular pressure of 1 eye(3.5%)returned to normal by trabeculectomy. The chamber depth of 29 eyes was increased. 8 eyes were suffered from mild corneal edema, and returned to normal after treatment. <p>CONCLUSION: Characterized by decreasing intraocular pressure, opening anterior chamber, and raising visual acuity, phacoemulsification with foldable intraocular lens implantation is a good operative therapy for primary angle-closure glaucoma complicated with cataract with preoperative goniosynechia closed ≤270°

Structural Trends Interpretation of the Metal-to-Semiconductor Transition in Deformed Carbon Nanotubes

Two mechanisms that drive metal-to-semiconductor transitions in single-walled carbon nanotubes are theoretically analyzed through a simple tight-binding model. By considering simple structural trends, the results demonstrate that metal-to-semiconductor transitions can be induced more readily in metallic zigzag nanotubes than in armchair nanotubes. Furthermore, it is shown that both mechanisms have the effect of making the two originally equivalent sublattices physically distinguishable.Comment: 4 pages, 4 figure

Quantum Entanglement in the S=1/2 Spin Ladder with Ring Exchange

In this paper we study the concurrence and the block-block entanglement in the $S=1/2$ spin ladder with four-spin ring exchange by the exact diagonalization method of finite cluster of spins. The relationship between the global phase diagram and the ground-state entanglement is investigated. It is shown that the block-block entanglement of different block size and geometry manifests richer information of the system. We find that the extremal point of the two-site block-block entanglement on the rung locates a transition point exactly due to SU(4) symmetry at this point. The scaling behavior of the block-block entanglement is discussed. Our results suggest that the block-block entanglement can be used as a convenient marker of quantum phase transition in some complex spin systems.Comment: 5 pages, 7 figure

Prediction of Vortex-Induced Vibration of Long Flexible Cylinders Modeled by a Coupled Nonlinear Oscillator: Integral Transform Solution

The Generalized Integral Transform Technique (GITT) was applied to predict dynamic response of Vortex-Induced Vibration (VIV) of a long flexible cylinder. A nonlinear wake oscillator model was used to represent the cross-flow force acting on the cylinder, leading to a coupled system of second-order Partial Differential Equations (PDEs) in temporal variable. The GITT approach was used to transform the system of PDEs to a system of Ordinary Differential Equations (ODEs), which was numerically solved by using the Adams-Moulton and Gear method (DIVPAG) developed by the International Mathematics and Statistics Library (IMSL). Numerical results were presented for comparison to those given by the finite difference method and experimental results, allowing a critical evaluation of the technique performance. The influence of variation of mean axial tension induced by elongation of flexible cylinder was evaluated, which was shown to be not negligible in numerical simulation of VIV of a long flexible cylinder.Indisponível

Renalase Deficiency in Heart Failure Model of Rats—A Potential Mechanism Underlying Circulating Norepinephrine Accumulation

BACKGROUND: Sympathetic overactivity and catecholamine accumulation are important characteristic findings in heart failure, which contribute to its pathophysiology. Here, we identify a potential mechanism underlying norepinephrine accumulation in a rat model of heart failure. METHODOLOGY/PRINCIPAL FINDINGS: Initially, we constructed a rat model of unilateral renal artery stenosis (n = 16) and found that the expression of renalase, a previously identified secreted amine oxidase, was markedly reduced in the ischemic compared to the non-ischemic kidney (protein: 0.295±0.085 versus 0.765±0.171, p<0.05). Subsequently, we utilized an isolated perfused rat kidney model to demonstrate that the clearance rate of norepinephrine decreased with reduction of perfusion flow. On the basis of these findings, we hypothesized the reduced renal blood supply which occurs in heart failure would result in impaired synthesis of renalase by the kidney and consequently reduced degradation of circulating norepinephrine. To verify this, we used a rat model of infarction-induced heart failure (n = 12 per group). In these rats, the flow velocity of renal artery, when measured at four weeks, is obviously lower in the operation group. Renal expression of renalase was reduced (protein: 0.476±0.043 for control, 0.248±0.029 for operation versus 0.636±0.151 for sham-operation) and this was associated with an increase in circulating norepinephrine (0.168±0.016 ng/mL for control, 0.203±0.019 ng/mL for operation versus 0.138±0.008 ng/mL for sham-operation). CONCLUSIONS/SIGNIFICANCE: Renalase expression is influenced by renal blood flow and impaired synthesis of renalase by the kidney may represent a potential mechanism underlying circulating norepinephrine accumulation in heart failure

Metal-to-semiconductor transition in squashed armchair carbon nanotubes

We investigate electronic transport properties of the squashed armchair carbon nanotubes, using tight-binding molecular dynamics and Green's function method. We demonstrate a metal-to-semiconductor transistion while squashing the nanotubes and a general mechanism for such transistion. It is the distinction of the two sublattices in the nanotube that opens an energy gap near the Fermi energy. We show that the transition has to be achieved by a combined effect of breaking of mirror symmetry and bond formation between the flattened faces in the squashed nanotubes.Comment: 4 papges, 4 figures, to appear in Phys. Rev. Let