Improved electrochemical performance of nitrocarburised stainless steel by hydrogenated amorphous carbon thin films for bone tissue engineering

In this study, hydrogenated amorphous carbon thin films, structurally similar to diamond‐like carbon (DLC), were deposited on the surface of untreated and plasma nitrocarburised (Nitrocarburizing‐treated) stainless steel medical implants using a plasma‐enhanced chemical vapour deposition method. The deposited DLC thin films on the nitrocarburising‐treated implants (CN+DLC) exhibited an appropriate adhesion to the substrates. The results clearly indicated that the applied DLC thin films showed excellent pitting and corrosion resistance with no considerable damage on the surface in comparison with the other samples. The CN+DLC thin films could be considered as an efficient approach for improving the biocompatibility and chemical inertness of metallic implants.Inspec keywords: tissue engineering, bone, biomedical materials, electrochemistry, amorphous state, carbon, hydrogen, thin films, plasma CVD, adhesion, corrosion resistance, surface hardeningOther keywords: electrochemical performance, plasma nitrocarburised stainless steel medical implants, hydrogenated amorphous carbon thin films, bone tissue engineering, plasma‐enhanced chemical vapour deposition method, adhesion, corrosion resistance, biocompatibility, chemical inertness, metallic implants, C:H     

A fast algorithm for feature extraction of hyperspectral images using the first order statistics

Multimedia Tools and Applications - A new supervised feature extraction method appropriate for small sample size situations is proposed in this work. The proposed method is based on the first-order...     

Strength violation effect on soft-error detection in sub-micron technology

In nanometer technologies, circuits are increasingly sensitive to various kinds of perturbations. Alpha particles and atmospheric neutrons induce single-event upsets (SEU), affecting memory cells, latches, and flip-flops. In addition, single-event transients (SET) can be initiated in the combinational logic and captured by the latches and flip-flop associated with the logic outputs. Designers cannot control the sources of soft-errors, but their effects can be mitigated through soft-error detection techniques. This paper proposes an algorithm to detect soft-errors at the switch-level caused by current spikes which can affect the driving strength. The offered approach uses a novel coding system to be applied in certain functions that are sensitive to strength variations. It is able to detect even the slight changes in signal strength caused by both cosmic rays and alpha particle from package contamination. Most soft-error detection techniques sense the logic changes in the circuit while this paper proves that a wide range of soft-errors are the result of strength violation in switch-level. Experimental results illustrate the importance of accurate simulation methods and stress the effect of driving strength changes in switch-level for soft-error detection in today’s technology.     

Ionic composition of cisternal CSF in acute respiratory acidosis: lack of effect of large dose bumetanide

Sodium/chloride cotransport carrier is known to be involved in transepithelial fluid absorption and secretion in various tissues. Recent studies indicate that Na,K,2Cl cotransport carrier also exists in the choroid plexus cells and inhibition of the carrier alters ionic composition of the choroidal tissue. In this study, we report the effects of large dose intravenous bumetanide, a potent inhibitor of Na,K,2Cl carrier, on cisternal CSF ionic composition in acute respiratory acidosis in pentobarbital-anesthetized mechanically ventilated dogs. Renal pedicles were ligated to prevent bumetanide-induced diuresis. The experimental group (Group II, n = 7) received 50 mg/kg of bumetanide intravenously and Group I (the control group, n = 7) received the vehicle. Analysis of serum and choroidal plexus tissue revealed bumetanide concentration of approximately 10(-5) mol/L in Group II. During 5 h of acute respiratory acidosis in both groups, the mean PaCO2 increased approximately 25 mm Hg, with comparable changes in CSF PCO2. In both groups, CSF [HCO3-] and [H+] increased approximately 3 mEq/L and 20 nEq/L, respectively. Furthermore, changes in CSF [Na+], [K+], [Ca2+], [Mg2+], [Cl-], and [Na(+)-Cl-] were also similar and were not significantly different from each other. These data show that bumetanide, at the dose that inhibits NaCl cotransport carrier, does not significantly affect ionic composition of cisternal CSF.     

Two‐Layer Terminal Sliding Mode Attitude Control of Satellites Equipped with Reaction Wheels

This paper addresses the global stability and robust attitude tracking problem of a near polar orbit satellite subject to unknown disturbances and uncertainties. It is assumed that the satellite is fully actuated by a set of reaction wheels (RW) as control actuators because of their relative simplicity, versatility and high accuracy. The terminal sliding mode control (TSMC) approach is utilized in a two‐level architecture to achieve control objectives. In the lower layer a detumbling‐like controller is designed which guarantees the finite‐time detumbling and tracking of the desired angular velocities and based on this result a robust attitude tracking controller is designed in the upper layer to achieve 3‐axis attitude tracking in the presence of unknown disturbances and bounded uncertainties. Robust stability and tracking properties of designed controllers are proved using the Lyapunov theory. Finally, a set of numerical simulation results are provided to illustrate the effectiveness and performance of the proposed control method.     

Advanced Bioresponsive Multitasking Hydrogels in the New Era of Biomedicine

Advanced forms of hydrogels have many inherently desirable properties and can be designed with different structures and functions. In particular, bioresponsive multifunctional hydrogels can carry out sophisticated biological functions. These include in situ single-cell approaches, capturing, analysis, and release of living cells, biomimetics of cell, tissue, and tumor-specific niches. They can allow in vivo cell manipulation and act as novel drug delivery systems, allowing diagnostic, therapeutic, vaccination, and immunotherapy methods. In the present review of multitasking hydrogels, new approaches and devices classified into point-of-care testing (POCT), microarrays, single-cell/rare cell approaches, artificial membranes, biomimetic modeling systems, nanodoctors, and microneedle patches are summarized. The potentials and application of each format are critically discussed, and some limitations are highlighted. Finally, how hydrogels can enable an “all-in-one platform” to play a key role in cancer therapy, regenerative medicine, and the treatment of inflammatory, degenerative, genetic, and metabolic diseases is being looked forward to.     

The synergy between multi-wall carbon nanotubes and Vulcan XC72R in microporous layers

In this study, the effects of the addition of multi-wall carbon nanotubes (MWCNTs) into a microporous layer (MPL) containing Vulcan XC72R on the oxygen reduction reaction (ORR) were studied. We tested various percentages of MWCNTs and Vulcan XC72R in the MPLs of gas-diffusion electrodes (GDEs) with various Pt loadings in the catalyst layer. The performance of the ORR in the electrodes was studied with linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and chronoamperometry. The structures of the MPLs were investigated by using scanning electron microscopy (SEM), mercury porosimetry (MP), and gas permeability. In addition, the optimum polytetrafluoroethylene (PTFE) content of the MPL was determined. Our results indicate that the performances of the GDEs are optimal under the following conditions: (a) 60 wt% MWCNTs and 40 wt% Vulcan XC72R with a Pt loading of 0.115 mg/cm²; (b) 80 wt% MWCNTs and 20 wt% Vulcan XC72R with a Pt loading of 0.5 mg/cm²; and (c) 40 wt% MWCNTs and 60 wt% Vulcan XC72R with a Pt loading of 1 mg/cm².     

A new hybrid feature extraction method in a dyadic scheme for classification of hyperspectral data

The feature extraction is an important preprocessing step of the classification procedure particularly in high-dimensional data with limited number of training samples. Conventional supervised feature extraction methods, for example, linear discriminant analysis (LDA), generalized discriminant analysis, and non-parametric weighted feature extraction ones, need to calculate scatter matrices. In these methods, within-class and between-class scatter matrices are used to formulate the criterion of class separability. Because of the limited number of training samples, the accurate estimation of these matrices is not possible. So the classification accuracy of these methods falls in a small sample size situation. To cope with this problem, a new supervised feature extraction method namely, feature extraction using attraction points (FEUAP) has been recently proposed in which no statistical moments are used. Thus, it works well using limited training samples. To take advantage of this method and LDA one, this article combines them by a dyadic scheme. In the proposed scheme, the similar classes are grouped hierarchically by the k-means algorithm so that a tree with some nodes is constructed. Then the class of each pixel is determined from this scheme. To determine the class of each pixel, depending on the node of the tree, we use FEUAP or LDA for a limited or large number of training samples, respectively. The experimental results demonstrate the better performance of the proposed hybrid method in comparison with other supervised feature extraction methods in a small sample size situation.     

A Synthesis of Two 1,4-Dihydropyridine Derivatives Labeled with Carbon-14 Using Conventional Heating,Microwave Irradiation,and Solid-State Reaction

Radiochemistry - Three modes of the reaction for labeling of dihydropyridine compounds were studied: thermal heating, microwave irradiation, and solid-state process.