Three-dimensional stress analysis of two-ply cord-rubber composite laminates

A three-dimensional finite element model was developed to predict the structural response of two-ply cord-rubber composite laminates. The present model treats a two-ply composite as an equivalent six-ply system with rubber and cord-rubber elements using 20-node isoparametric finite elements. The accuracy of the present model is demonstrated by comparing the results to the existing alternative solutions for linear analysis. The effects of different analyses, cord orientations, rubber material models and interply rubber thickness on interply stresses are presented for ± steel cord-rubber composite laminates. The presented results of interface and interply stresses, and interply strains across the width as well as through the thickness illustrate behavior of two-ply cord-rubber composites.     

Selective Antifolates for Chemically Labeling Proteins in Mammalian Cells

Antifolate labels : Molecules that bind specifically and with high affinity to proteins can be developed into powerful tools for chemical biology. The interaction between substituted 5‐benzyl pyrimidines and dihydrofolate reductase can be exploited for chemically labeling fusion proteins in mammalian cells.

     

MXenes Antibacterial Properties and Applications: A Review and Perspective

The mutations of bacteria due to the excessive use of antibiotics, and generation of antibiotic-resistant bacteria have made the development of new antibacterial compounds a necessity. MXenes have emerged as biocompatible transition metal carbide structures with extensive biomedical applications. This is related to the MXenes’ unique combination of properties, including multifarious elemental compositions, 2D-layered structure, large surface area, abundant surface terminations, and excellent photothermal and photoelectronic properties. The focus of this review is the antibacterial application of MXenes, which has attracted the attention of researchers since 2016. A quick overview of the synthesis strategies of MXenes is provided and then summarizes the effect of various factors (including structural properties, optical properties, surface charges, flake size, and dispersibility) on the biocidal activity of MXenes. The main mechanisms for deactivating bacteria by MXenes are discussed in detail including rupturing of the bacterial membrane by sharp edges of MXenes nanoflakes, generating the reactive oxygen species (ROS), and photothermal deactivating of bacteria. Hybridization of MXenes with other organic and inorganic materials can result in materials with improved biocidal activities for different applications such as wound dressings and water purification. Finally, the challenges and perspectives of MXene nanomaterials as biocidal agents are presented.     

The compressive failure of alumina containing controlled distributions of flaws

Alumina samples containing a controlled number and size of crack-line flaws were tested in simple compression. Crack extension and linkage were observed during loading by in situ scanning electron microscopy. Young's modulus, the stress for the initiation of crack growth and that for final failure were recorded. The observations, the most complete on a real ceramic system (as opposed to model materials like PMMA) confirm mechanisms which have been proposed for compressive fracture of brittle solids.     

Antialiasing the Hough transform

The discretization of the Hough transform parameter plane is considered. It is shown that the popular accumulator method implies sampling of a nonbandlimited signal. The resultant aliasing accounts for several familiar difficulties in the algorithm. Bandlimiting the parameter plane would allow Nyquist sampling, thus aliasing could be avoided. An effectively alias-free Hough algorithm is presented and analyzed. The uncertainty principle of signal representation induces a compromise between image-space localization and parameter-space sampling density, as well as an upper bound on the performance of the algorithm. These results contribute to the development of a design methodology for hierarchical “coarse to fine” Hough algorithms.     

Hybrid phenolic friction composites containing Kevlar® pulp Part 1. Enhancement of friction and wear performance

The friction and wear characteristics of control (without Kevlar® pulp) and hybrid (with Kevlar® pulp) phenolic composites containing milled E-glass or steel were determined at various counterface speeds and temperatures using a Chase friction tester. In general, Kevlar® pulp significantly improved the wear resistance and decreased the coefficient of friction for both types of hybrid composites. Kevlar® pulp also imparted excellent frictional stability at high speeds in steel-fiber composites and significantly reduced higher frequency ( > 5 kHz) noise at high speeds in both steel and glass-fiber composites. The stabilization of the coefficient of friction and reduction of noise was not due to the reduction of the coefficient of friction because it also occurred at constant frictional force. The addition of Kevlar® pulp to a steel-fiber-containing formulation significantly improved its overall performance.     

Comparison of ethanol electro-oxidation on Pt/C and Pd/C catalysts in alkaline media

The ethanol electro-oxidation behaviors of Pt/C and Pd/C in alkaline media were compared using potentiodynamic and potentiostatic methods. Various ethanol and alkaline concentrations were studied. In addition, the temperature effect of ethanol oxidation was investigated. The Pd/C showed a higher activity toward ethanol oxidation than the Pt/C, especially in the potentiostatic measurement. This is mainly due to the higher oxyphilic characteristics of the Pd/C and the relatively inert nature of the Pd/C on C–C bond cleavage. The apparent activation energies of the ethanol oxidation on the Pd/C in alkaline media varied from 26.6 to 30.4 kJ mol⁻¹, depending on the potentials. The Tafel slopes could be divided into two parts on both catalysts: at low overpotentials, the Tafel slope on both the Pt/C and the Pd/C was close to 120 mV dec⁻¹ at all temperatures; at high overpotentials, the Tafel slope was ca. 260 mV dec⁻¹ on the Pd/C at all temperatures, but was much higher on the Pt/C, especially at high temperatures. Based on these results, it is concluded that Pd/C has less poisoning effect and higher activity than Pt/C for selective oxidation of ethanol to acetate.