Electrodeposition and electro-catalytic study of nanocrystalline Ni–Fe alloy

This paper presents the electrodeposition protocol for development of a stable, inexpensive and efficient electrode material for water splitting reaction. Nanocrystalline Ni–Fe alloy coatings were deposited on copper electrode from acidic bath, at different cathode current densities (c.d). Coatings were tested for their electro-catalytic behaviours, namely for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 6 M KOH by cyclic voltammetry and chrono-potentiometry techniques. Experimental results demonstrated that these coatings can be used as potential material for water electrolysis. The corrosion stability of these coatings has also been tested in their working conditions (6 M KOH) by DC polarization method. The deposition conditions of Ni–Fe alloy were optimized for peak performance for both electro-catalytic reactions and corrosion stability. Ni–Fe alloy coatings deposited towards low and high c.d limits were found to be the better materials for OER and HER, respectively from same electrolytic solution. Further, Ni–Fe coating deposited at 6.0 Ad m⁻² was found to be the most corrosion resistant. The structure-property relationship of electrodeposited coatings has been discussed by exploring PXRD, EDX and FESEM study.     

Optimization of deposition conditions for development of high corrosion resistant Zn-Fe multilayer coatings

Composition modulated multilayer alloy (CMMA) coating of Zn-Fe was developed galvanostatically on mild steel through single bath technique (SBT), using thiamine hydrochloride as additive. Electrodeposits with different coating matrices were developed, using square current pulses. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods were used to assess the corrosion performance of the coatings. The cyclic cathode current densities (CCCDs) and number of layers were optimized, for highest corrosion resistance. Experimental results showed that CMMA Zn-Fe coating, developed at 2.0-4.0 A/dm², having 300 layers is ∼30 times higher corrosion resistant than corresponding monolithic alloy of same thickness. The corrosion resistance increased with number of layers up to a certain number of layers; and then decreased. The better corrosion resistance was attributed to the dielectric barrier at the interface, evidenced by dielectric spectroscopy. The formation of multilayer and corrosion mechanism was analyzed using scanning electron microscopy (SEM).     

Development of nano-structured cyclic multilayer Zn-Ni alloy coatings using triangular current pulses

Cyclic multilayer alloy (CMA) deposits of Zn-Ni were developed on mild steel from sulphate bath having thiamine hydrochloride (THC) and citric acid (CA) as additives. CMA coatings were developed galvanostatically using triangular current pulses, under different conditions of cyclic cathode current density (CCCD’s) and number of layers. The corrosion behaviors of the coatings were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy methods, and were compared with that of monolayer Zn-Ni alloy of same thickness. At optimal configuration, CMA coating represented as, (Zn-Ni)_2.0/5.0/300 was found to exhibit ∼40 times better corrosion resistance compared to monolayer alloy, (Zn-Ni)_3.0. Cyclic voltammetry study demonstrated that THC and CA have improved the appearance of the deposit by complexation with metal ions. The corrosion protection efficacy of CMA coatings was attributed to the difference in phase structure of the alloy in successive layers, evidenced by XRD analysis. The formation of multilayer and corrosion mechanism was analyzed by Scanning Electron Microscopy (SEM) study.     

Doctor''s future

In this paper it is described the detection enteroxigenic Escherichia coli LT (+). This method is based on the amplification of a DNA fragment of 400 pairs of bases by polymerase chain reaction (PRC). The oligonucleotides were designed by the authors and the characteristic patterns were observed when the samples were submitted to an electrophoresis in an Agarose gel at 2%. The PCR had positive results with the strains of Escherichia coli 0:149 K; 88 (LT+) collection and with 20 strains isolated from patients with acute diarrhea. Negative results were found in Escherichia coli 0:101 K:99 NM (ST+), Vibrio cholerae 01 and Aeromonas hydrophila.     

Hyperferritinaemia in the absence of iron overload

We present a case of a 3-month-old boy presenting with fulminating meningococcal septicaemia associated with extensive peripheral gangrene requiring amputation of three limbs. The surgical management options and the role of early fasciotomy are discussed.     

Synthesis,structure and IR absorption studies of LnBaCuCoO5 (Ln=rare earth) oxides

A series of oxides LnBaCuCoO₅ (Ln=Pr, Nd, Sm, Dy, Gd, Ho and Er) have been synthesized by ceramic method. The oxides crystallize in a tetragonal structure, isostructural to YBaCuCoO₅. All the oxides in the series are semiconducting. IR spectra of these oxides show distinct absorption bands at 630 cm⁻¹, 550 cm⁻¹ and 330 cm⁻¹ which are assigned toE,A ₂ andA ₁ modes respectively. Doping of holes in these oxides, by calcium substitution in Er_1−x Ca _x BaCuCoO_5−x (up tox ⋍ 0·3) was done but, these oxides did not show metallic behaviour. Contribution no 1175 from Solid State and Structural Chemistry Unit.