The role of the electron spin in chemistry and biology has received much attention recently owing to to the possible electromagnetic field effects on living organisms and the prospect of using molecules in the emerging field of spintronics. Recently the chiral-induced spin selectivity effect was observed by electron transmission through organic molecules. In the present study, we demonstrated the ability to control the spin filtering of electrons by light transmitted through purple membranes containing bacteriorhodopsin (bR) and its D96N mutant. The spin-dependent electrochemical cyclic voltammetry (CV) and chronoamperometric measurements were performed with the membranes deposited on nickel substrates. High spin-dependent electron transmission through the membranes was observed; however, after the samples were illuminated by 532 nm light, the spin filtering in the D96N mutant was dramatically reduced whereas the light did not have any effect on the wild-type bR. Beyond demonstrating spin-dependent electron transmission, this work also provides an interesting insight into the relationship between the structure of proteins and spin filtering by conducting electrons.

This paper presents the results of a study of the electroless deposition process and the film properties of cobalt-tungsten-boron ͓Co͑W, B͔͒ thin layers on thin copper films. Two solutions based on cobalt citric complexes and dimethylaminoborane reducing agent were developed. Tungsten was introduced into the solutions by using either sodium tungstate or tungsten acid. The deposited thin-film composition was characterized as a function of the bath formulation by X-ray photoemission spectroscopy. Electroless deposition was studied through electrochemical approach via linear sweep voltammetry analysis of the following two partial reactions: a. metal reduction and b. the oxidation of the reducing agent at the Co͑W, B͒ plated electrodes. In situ mixed potentials of the process for different electrolytes were measured. The deposition rate of cobalt alloys was gravimetrically measured as well. Comparison between direct experimental values of the mixed potential and deposition rate with those derived theoretically from the current-potential curves for partial reactions shows the electrochemical nature of the deposition reaction with current yield value of about 0.7-0.8 and 0.98 for solution with sodium tungstate and alkali metals free bath, respectively. The optimal conditions ͑i.e., temperature, pH͒ and composition of aqueous solution for the deposition of Co͑W, B͒ films were defined. Those films can be applied as both barrier and capping layers for ultra-large-scale-integration metallization for integrated circuits and microsystemtechnology applications.Metal and metal alloy coatings have a wide application range in numerous technologies featuring the increased functionality and reliability of different industry products. Metallic layers act as thermal and electricity conductors, protective shields, and magnetic media; they provide necessary chemical, mechanical, electrical, magnetic, and optical properties. They are also used for decorative and corrosion protection purposes.Electroless metal deposition remains one of the most attractive technologies for thin metallic coating formation due to few wellknown process advantages such as selective and conformal deposition, self-aligning, low processing temperature, high quality of the films, and the ability to deposit alloys. Increased attention to electroless and electroplating processing in microelectronics was raised in the last decade due to the introduction of copper interconnects to VLSI integrated circuits ͑ICs͒ and the forthcoming transition to sub-100 nm technology. The electroless method is under intensive study for future ͑i.e., with critical dimensions of 45 nm and below͒ ultralarge-scale integration ͑ULSI͒.Cobalt and cobalt alloys find their application in the production of hard materials, magnets, tire adhesives, catalysts, colorants, chemicals, and batteries. 1 Cobalt alloy coatings are distinguished by their unique magnetic and mechanical properties, high oxidation stability, and wear resistance. The magnetic properties of electrodeposited cobalt alloys are ...

No abstract

No abstract

Field effect transistors (FETs) may respond to charge variations occurring when proteins are adsorbed to the gate surface. The electrolyte electrostatic screening allows a practical detection of charges that are only within a distance of approximately the double layer thickness, which is related to the Debye length in the electrolyte. Hence, operating the FET biomolecular sensors at the highest possible ionic concentration improves reproducibility; however, it may reduce the signal if the concentration is too high. Here, we propose an optimization method of the buffer ionic concentration using a figure of merit “charge number,” Znormald , which is defined as the ratio between the effective number of the surface charges and the number of immobilized molecules. The theoretical Znormald was calculated using a three-dimensional conformation data taken from the Protein Data Bank. The Znormald was obtained from the total number of four charged amino acids of avidin, arginine (positive), lysine (positive), aspartic acid (negative), and glutamic acid (negative), which are within the double layer length from the surface. To verify this model, we chose avidin–biotin interaction. The experimental Znormald , which was obtained for three buffer concentrations, matched the theoretical Znormald . This method shortens the solution calibration time and reduces the analyte amount.