A Suspended Nanogap Formed by Field-Induced Atomically Sharp Tips

A sub-nanometer scale suspended gap (nanogap) defined by electric field-induced atomically sharp metallic tips is presented. A strong local electric field (\u3e109 V=m) across micro/nanomachined tips facing each other causes the metal ion migration in the form of dendrite-like growth at the cathode. The nanogap is fully isolated from the substrate eliminating growth mechanisms that involve substrate interactions. The proposed mechanism of ion transportation is verified using real-time imaging of the metal ion transportation using an in situ biasing in transmission electron microscope (TEM). The configuration of the micro/nanomachined suspended tips allows nanostructure growth of a wide variety of materials including metals, metal-oxides, and polymers. VC 2012 American Institute of Physics

DETERMINATION OF LINEAR AND NONLINEAR ROLL DAMPING COEFFICIENTS OF A SHIP SECTION USING CFD

The most prevalently used method to obtain the nonlinear roll damping coefficient is the free roll decay test. However, this method can only be conducted at the resonance frequency and thus cannot consider the effect of the frequency. This is a certain limitation as the resonance frequency can be changed at any time by the ship’s loading conditions. Therefore, it is worth investigating the frequency dependency of the nonlinear roll damping coefficients. In this study, a numerical method was proposed to derive the linear and nonlinear roll damping coefficients of ships at different frequencies. Fully nonlinear CFD simulations of forced harmonic roll motion were conducted and the roll damping coefficients were calculated. Then, the damping coefficients were decomposed into the linear and nonlinear components using the linear regression analysis. The linear roll damping coefficients were compared with potential coefficients and showed a good agreement, while the nonlinear roll damping coefficients were compared with the coefficients calculated using a semi-empirical method. The nonlinear roll damping coefficients calculated from the proposed method showed a strong frequency dependency. Finally, possible rationales for the frequency dependence of the nonlinear roll damping coefficient were investigated

A NUMERICAL STUDY ON THE OPEN WATER PERFORMANCE OF A PROPELLER WITH SINUSOIDAL PITCH MOTION

When a ship operates in waves, the ship moves with 6 degrees-of-freedom, and a propeller at the stern of the ship cannot avoid moving due to the ship motion. Therefore, it is important to analyse the propulsion performance while considering the ship motion in waves for efficient ship operation. The pitch motion of the ship has a dominant effect on the variation of the propeller performance and results in sinusoidal pitch motion of the propeller. In this study, a numerical analysis was done using a KP458 model propeller with a diameter of 10 cm, which was designed for the KLVCC2 body plan. The propeller performance was calculated using computational fluid dynamics (CFD) at several constant tilt angles. Numerical simulations were then conducted with sinusoidal pitch motion in several conditions of varying pitch angle. The variations of the thrust and torque of the propeller in sinusoidal pitch motion were compared with the results obtained in constant tilt angles

Magnetic Topological Transistor Exploiting Layer-Selective Transport

We propose a magnetic topological transistor based on MnBi$_{2}$Te$_{4}$, in which the "on" state (quantized conductance) and the "off" state (zero conductance) can be easily switched by changing the relative direction of two adjacent electric fields (parallel vs. antiparallel) applied within a two-terminal junction. We explain that the proposed magnetic topological transistor relies on a novel mechanism due to the interplay of topology, magnetism, and layer degrees of freedom in MnBi$_{2}$Te$_{4}$. Its performance depends substantially on film thickness and type of magnetic order. We show that "on" and "off" states of the transistor are robust against disorder due to the topological nature of the surface states. Our work opens an avenue for applications of layer-selective transport based on the topological van der Waals antiferromagnet MnBi$_{2}$Te$_{4}$

Short-Term Effects of Combined Serial Casting and Botulinum Toxin Injection for Spastic Equinus in Ambulatory Children with Cerebral Palsy

PURPOSE: The purpose of this paper is to test the hypothesis that combination therapy of serial cast and botulinum toxin type A (BTX-A) injection can further enhance the effects of a BTX-A injection in ambulant children with cerebral palsy (CP) who have an equinus foot. MATERIALS AND METHODS: Children in group A (30 legs of 21 children) received a serial casting application after an injection of BTX-A, and children in group B (25 legs of 17 children) received only a BTX-A injection. Assessments were performed before the intervention and 1 month after the intervention. RESULTS: After the intervention, there were significant improvements in tone, dynamic spasticity, and passive range of motion (ROM) in both groups. However, the changes were greater in group A than in group B. Dimension D (standing) in Gross Motor Function Measure (GMFM)-66 was significantly improved in group A but not in group B. On the other hand, there were no significant changes in dimension E (walking, running, jumping) in GMFM-66 in either group. CONCLUSION: The results of our study suggest that a serial casting application after BTX-A injection can enhance the benefits of BTX-A injection in children with cerebral palsy.ope

Enhanced cardiac expression of two isoforms of matrix metalloproteinase-2 in experimental diabetes mellitus.

BackgroundDiabetic cardiomyopathy (DM CMP) is defined as cardiomyocyte damage and ventricular dysfunction directly associated with diabetes independent of concomitant coronary artery disease or hypertension. Matrix metalloproteinases (MMPs), especially MMP-2, have been reported to underlie the pathogenesis of DM CMP by increasing extracellular collagen content.PurposeWe hypothesized that two discrete MMP-2 isoforms (full length MMP-2, FL-MMP-2; N-terminal truncated MMP-2, NTT-MMP-2) are induced by high glucose stimulation in vitro and in an experimental diabetic heart model.MethodsRat cardiomyoblasts (H9C2 cells) were examined to determine whether high glucose can induce the expression of the two isoforms of MMP-2. For the in vivo study, we used the streptozotocin-induced DM mouse heart model and age-matched controls. The changes of each MMP-2 isoform expression in the diabetic mice hearts were determined using quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemical stains were conducted to identify the location and patterns of MMP-2 isoform expression. Echocardiography was performed to compare and analyze the changes in cardiac function induced by diabetes.ResultsQuantitative RT-PCR and immunofluorescence staining showed that the two MMP-2 isoforms were strongly induced by high glucose stimulation in H9C2 cells. Although no definite histologic features of diabetic cardiomyopathy were observed in diabetic mice hearts, left ventricular systolic dysfunction was determined by echocardiography. Quantitative RT-PCR and IHC staining showed this abnormal cardiac function was accompanied with the increases in the mRNA levels of the two isoforms of MMP-2 and related to intracellular localization.ConclusionTwo isoforms of MMP-2 were induced by high glucose stimulation in vitro and in a Type 1 DM mouse heart model. Further study is required to examine the role of these isoforms in DM CMP