Corrosion behavior of Ce-doped Ni-10Cu-11Fe-6Al (wt%) inert anode in molten CaCl2 salt

In this research the effect of cerium dopingon corrosion behavior of Ni-10 Cu-11 Fe-6 Al(wt%) alloy as a novel inert anode in titanium electrolytic production was investigated. The samples, including un-doped and Ce-doped nickel-based alloys, were prepared using vacuum induction melting(VIM) process and then exposed to the electrolysis in molten calcium chloride at 900C at à1.6 V versus graphite reference electrode for different immersion time. The surface and cross-section of the samples were characterized using scanning electron microscopy(SEM), and their electrochemical behavior was investigated by electrochemical impedance spectroscopy(EIS). The results show that the un-doped samples have greater number of voids and porosities as compared to that of the 0.0064 wt% Ce-doped samples(as the optimum content of cerium in the alloy). Thus, the nickel-based alloy becomes less sensitive to the pitting by addition of cerium. The corrosion penetration depth reaches about 244 mm after 16 h of electrolysis in the un-doped sample, while was approximately 103 mm for the 0.0064 wt% Ce-doped sample, which is an indication that the corrosion penetration depth decreases by adding small amounts of Ce.     

Measurement of milling tool vibrations during cutting using laser vibrometry

Spindle and tool vibration measurements are of great importance in both the development and monitoring of high-speed milling. Measurements of cutting forces and vibrations on the stationary spindle head is the most used technique today. But since the milling results depend on the relative movement between the workpiece and the tool, it is desirable to measure on the rotating tool as close to the cutters as possible. In this paper the use of laser vibrometry (LDV) for milling tool vibration measurements during cutting is demonstrated. However, laser vibrometry measurements on rotating surfaces are not in general straight forward. Crosstalk between vibration velocity components and harmonic speckle noise generated from the repeating revolution of the surface topography are problems that must be considered. In order to overcome the mentioned issues, a cylindrical casing with a highly optically smooth surface was manufactured and mounted on the tool to be measured. The spindle vibrations, radial tool misalignment, and out-of-roundness of the measured surface were filtered out from the signal; hence, the vibrations of the cutting tool were resolved. Simultaneous measurements of cutting forces and spindle head vibrations were performed and comparisons between the signals were conducted. The results showed that vibration velocities or displacements of the tool can be obtained with high temporal resolution during cutting load and therefore the approach is proven to be feasible for analysing high-frequency milling tool vibrations.     

Vapor Liquid Equilibria for Ionic Liquid/Ethanol/Water Systems and the Effect of Anion Hydrolysis

The performance of two tetrafluoroborate-based ionic liquids (ILs) as entrainers in the dehydration of water/ethanol azeotropic mixtures was evaluated. Isobaric vapor-liquid equilibrium (VLE) data were measured for the systems ethanol/water/1-butyl-3-methyl imidazolium tetrafluoroborate and ethanol/water /n-butylpyridinium tetrafluoroborate including the azeotropic region. VLE data for the ethanol/water, ethanol/IL, and water/IL binary mixtures were obtained at 100 kPa. The hydrolysis of the tetrafluoroborate anion was studied for both types of ILs by ¹⁹F NMR analysis. The hydrolysis of the tetrafluoroborate anion does not have much effect on the ethanol/water VLE. The ¹⁹F NMR analysis indicated that hydrolysis occurred at high mole fractions of water.     

Preparation and evaluation of novel nano-bioglass/gelatin conduit for peripheral nerve regeneration

Peripheral nerves are exposed to physical injuries usually caused by trauma that may lead to a significant loss of sensory or motor functions and is considered as a serious health problem for societies today. This study was designed to develop a novel nano bioglass/gelatin conduit (BGGC) for the peripheral nerve regeneration. The bioglass nanoparticles were prepared by sol–gel technique and characterized using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis. The interfacial bonding interaction between the nano-bioglass and gelatin in the developed conduits was assessed by FTIR. The surface morphology and pore size of the nanocomposite were investigated through scanning electron microscopy with the pore size of the conduits being 10–40 μm. Biocompatibility was assessed by MTT assay which indicated the BGGC to have good cytocompatibility. The guidance channel was examined and used to regenerate a 10 mm gap in the right sciatic nerve of a male Wistar rat. Twenty rats were randomly divided into two experimental groups, one with the BGGC and the other being normal rats. The gastrocnemius muscle contractility was also examined at one, two and three months post-surgery in all groups using electromyography (EMAP). Histological and functional evaluation and the results obtained from electromyography indicated that at three months, nerve regeneration of the BGGC group was statistically equivalent to the normal group (p > 0.05). Our result suggests that the BGGC can be a suitable candidate for peripheral nerve repair.     

Surgical tool motion during conventional freehand and robot-assisted microsurgery conducted using neuroArm

Surgical tool motion during microsurgery could arguably reflect surgical performance. This paper reports on how the motion of a surgical tool correlates or differs between conventional freehand surgery and robot-assisted surgery. In this pilot study, components of the position and orientation as well as the linear and angular velocities of a surgical tool, over the same period of operation, are compared during the two scenarios. For freehand surgery, a bipolar forceps is retrofitted with a tracking system to measure translational and rotational components of the tool motion. In robot-assisted surgery, the position and orientation components are obtained using kinematics of the neuroArm image-guided robotic system. A cross correlation analysis was used to investigate correlation between each pair of displacement or velocity components from freehand and robot-assisted scenarios to indicate how strongly or weakly two sets of data are linked together. The absolute maximum value of the cross correlation coefficient is calculated for each pair of components to quantitatively investigate the correlation between two sets of data. Results showed that the positional and rotational components, reflecting the surgical workspace, in both scenarios are correlated. However, for the cases studied, surgical tool rate of motion differs between the two scenarios. Results are important as they can be utilized to design robot-assisted neurosurgical systems that reflect characteristics of freehand surgery gained by surgeons through years of training, knowledge, and experience.     

Oscillatory Thermopower Waves Based on Bi2Te3 Films

Exothermic chemical reactions that are coupled to Bi₂Te₃ porous layers, which are deposited onto terracotta or alumina (Al₂O₃) substrates, are used to produce self‐propagating thermal waves that are guided along the surface. Nitrocellulose is used as the highly reactive chemical. Bi₂Te₃ is employed because of its large Seebeck coefficient and high electrical conductivity. For the Al₂O₃ based structures, the thermal conduction of the substrate results in strong oscillations of the output signals. Such thermopower waves produce a power as large as 10 mW and voltages as high as 150 mV. The power per mass ratio of the developed system is quite remarkable, namely, on the order of 1 kW kg^?1. Depending on the thermal conductivity of the substrate used, the wave front average propagation velocity is either slow (ca. 0.009 m s^?1 for terracotta) or much faster (on the order of 0.4 m s^?1 for Al₂O₃). We have used a mathematical model based on two coupled heat transport equations, in conjunction with the chemical reaction equation, to predict the behavior of the system, which describes the average propagation velocity and the time between oscillation peaks.     

Performance evaluation of Web server workloads in Xen‐based virtualized computer system: analytical modeling and experimental validation

Recent developments in the field of virtualization technologies have led to renewed interest in performance evaluation of these systems. Nowadays, maturity of virtualization technology has made a fuss of provisioning IT services to maximize profits, scalability and QoS. This pioneer solution facilitates deployment of datacenter applications and grid and Cloud computing services; however, there are challenges. It is necessary to investigate a trade‐off among overall system performance and revenue and to ensure service‐level agreement of submitted workloads. Although a growing body of literature has investigated virtualization overhead and virtual machines interference, there is still lack of accurate performance evaluation of virtualized systems. In this paper, we present in‐depth performance measurements to evaluate a Xen‐based virtualized Web server. Regarding this experimental study; we support our approach by queuing network modeling. Based on these quantitative and qualitative analyses, we present the results that are important for performance evaluation of consolidated workloads on Xen hypervisor. First, demands of both CPU intensive and disk intensive workloads on CPU and disk are independent from the submitted rate to unprivileged domain when dedicated core(s) are pinned to virtual machines. Second, request response time not only depends on processing time at unprivileged domain but also pertains to amount of flipped pages at Domain 0. Finally, results show that the proposed modeling methodology performs well to predict the QoS parameters in both para‐virtualized and hardware virtual machine modes by knowing the request content size. Copyright © 2015 John Wiley & Sons, Ltd.     

Liquid Metal Actuator for Inducing Chaotic Advection

Chaotic advection plays an important role in microplatforms for a variety of applications. Currently used mechanisms for inducing chaotic advection in small scale, however, are limited by their complicated fabrication processes and relatively high power consumption. Here, a soft actuator is reported which utilizes a droplet of Galinstan liquid metal to induce harmonic Marangoni flow at the surface of liquid metal when activated by a sinusoidal signal. This liquid metal actuator has no rigid parts and employs continuous electrowetting effect to induce chaotic advection with exceptionally low power consumption. The theory behind the operation of this actuator is developed and validated via a series of experiments. The presented actuator can be readily integrated into other microfluidic components for a wide range of applications.