Control of Nanoscale Environment to Improve Stability of Immobilized Proteins on Diamond Surfaces

Immunoassays for detection of bacterial pathogens rely on the selectivity and stability of bio-recognition elements such as antibodies tethered to sensor surfaces. The search for novel surfaces that improve the stability of biomolecules and assay performance has been pursued for a long time. However, the anticipated improvements in stability have not been realized in practice under physiological conditions because the surface functionalization layers on commonly used substrates, silica and gold, are themselves unstable on time scales of days. In this paper, we show that covalent linking of antibodies to diamond surfaces leads to substantial improvements in biological activity of proteins as measured by the ability to selectively capture cells of the pathogenic bacterium Escherichia coli O157:H7 even after exposure to buffer solutions at 37 °C for extended periods of time, approaching 2 weeks. Our results from ELISA, XPS, fluorescence microscopy, and MD simulations suggest that by using highly stable surface chemistry and controlling the nanoscale organization of the antibodies on the surface, it is possible to achieve significant improvements in biological activity and stability. Our findings can be easily extended to functionalization of micro and nanodimensional sensors and structures of biomedical diagnostic and therapeutic interest.     

Modeling and Diagnosing Eccentricity Fault Using Three-dimensional Magnetic Equivalent Circuit Model of Three-phase Squirrel-cage Induction Motor

This article presents the three-dimensional modeling of an induction motor using a magnetic equivalent circuit. The main goal of introducing the three-dimensional model is to include axial fluxes in the machine equations. Furthermore, enhancement of the precision of teeth flux estimation and air-gap permeances, as the most important and dominant factors, is another achievement of this model compared to that of the two-dimensional model. This increases the accuracy of the estimated torque. Although it is possible to include the impact of the bar skew in the two-dimensional modeling using a magnetic equivalent circuit, this can be included more precisely in the three-dimensional model due to the three-dimensional nature of the bar skew. Therefore, the three-dimensional model as an efficient method with rapid computations and suitable precision is used for modeling various types of eccentricity. It is shown that the three-dimensional model results are closer to the experimental results compared to that of the two-dimensional model. This confirms the merit of the three-dimensional model. Also, this method can be a proper substitution to the finite-element method in modeling a machine under fault and fault diagnosis.     

Effect of natural ageing on the mechanical properties of molybdenum polycrystals

Natural ageing of 99.95 at.% Mo polycrystals annealed at 700 °C influences its mechanical properties to a considerable extent. It is found that natural ageing for 6 months reduces the ductility by about 70% whereas yield stress and ultimate tensile strength are decreased by about 20 and 18% respectively. The stress-relaxation rate measured at a given initial stress level at which deformation is interrupted to observe stress relaxation at constant strain, is faster in aged specimens compared with that in unaged ones. Similarly, the strain-rate sensitivity of flow stress for a given stress level is also increased on natural ageing. The rate process of stress relaxation and of plastic flow at rather high strains corresponding to the parabolic stage of work hardening appears to be vacancy migration.     

Advanced Biometric Pen System for Recording and Analyzing Handwriting

Handwriting dynamics which reflect fine motor skills of writers can be recorded with pen based writing systems. They are generally equipped with a diversity of sensors, such as pen tip pressure and tilt-acceleration sensors mounted inside the pen or pen tip x-y position sensors integrated on a specific graphic tablet. Such writing systems are essentially applied for biometric personal identification or handwriting recognition. In this paper, an advanced biometric pen based system for capturing and analyzing handwriting dynamics of a person is presented. Features of the device as well as evaluation of its sensor data are discussed. The system actually comprises a standard WACOM graphic tablet where its input pen is equipped additionally with a sensor to measure the grip pressure of fingers holding the pen. By combining x-y position data of the tablet and grip pressure data of the pen an improvement of performance in handwriting and person recognition is achieved. The experimental results have shown that among the single sensors, the grip sensor data gives best recognition accuracy and improves the recognition rates of handwritten PINs or persons by about 1%, when fused with x-y position data. It shows excellent accuracy in handwriting recognition and depicts detailed information about fine motor skill which is primarily because of data sampled by the finger grip pressure sensor. The enhanced input device has great promise not only for biometrics but also for biomedical applications.     

Cationization of cellulose fibers for composites

In this work, composites were made by improved bonding of the cationized cellulosic fabric and some anionic matrix like Carboxymethyl Cellulose (CMC). Mercerized cotton fabric was cationized using cationization agent, TEXAMIN ECE with varying percentage from 1 to 10%. Those cationized cotton samples were incorporated in anionic matrices and the resultant composites were tested for mechanical properties on Universal Textile Tensile Testing machine. In the case of CMC as the matrix for the cationized reinforcement, the increasing trend in the tensile strength and elongation at break was observed. Scanning Electron Microscope images showed no extraordinary changes in the physical appearance of the cationized samples. Thermograms derived from Differential Scanning Calorimetry were informative for the evaluation of the thermal behavior of composites.