Removal of cyanide in aqueous solution by oxidation with hydrogen peroxide in presence of copper-impregnated activated carbon

This work is devoted to the removal of free cyanide from aqueous solution by oxidation with hydrogen peroxide H₂O₂ catalyzed by copper-impregnated activated carbon. Effects of initial molar ratio [H₂O₂]₀/[CN⁻]₀, copper-impregnated activated carbon amount, pH and the temperature on cyanide removal have been investigated.The presence of copper-impregnated activated carbon has increased the reaction rate showing thus a catalytic activity. The rate of cyanides removal increases with the raise of the initial molar ratio [H₂O₂]₀/[CN⁻]0 and decreases with the increase in the pH from 8 to 12. The increase in the copper-impregnated activated carbon amount from 1.5 to 10 g/L in reaction solution has a beneficial effect. Beyond this value, the impact of activated carbon amount is not anymore significant. The temperature does not have a significant effect between 20 and 35 °C. The four successive times re-use of catalyst shows a good stability. The kinetics of cyanide removal has been found to be of pseudo-second-order with respect to cyanide and the rate constants have been determined. This process seems very interesting because the rate of cyanides removal is very fast, the reaction does not use soluble metal catalyst and it consumes only hydrogen peroxide as chemical product.     

On the grain boundary internal friction peak of α-brasses

A conventional Ke pendulum was used to investigate the temperature dependence of internal friction for thoroughly annealed samples of Cu-30% Zn. The relaxation peak observed at 330° C at a frequency of vibration 0.60 Hz was attributed to grain boundary diffusion. The energy activating the process amounted to 1.84 eV and characterized the activation energy for self diffusion in copper. The relaxation strength showed strain amplitude dependence, however, the activation energy and peak temperature did not show any amplitude dependence. The effect of solute atom concentration, cold work and vacancies was also tested.     

Fair and Reasonable Markup (FaRM) Pricing Model

The Fair and Reasonable Markup (FaRM) is the smallest markup that satisfies the Required Rate of Return (RRR) of the contractor for the particular (or at least the general risk‐class of) project at hand. The model is based on reasonable and easily‐accessible information, and will result in a Minimum Acceptable Price (MAP). The firm cannot accept the project at a price below this MAP without diminishing the “equityholders' wealth.” A modified version of the FaRM Pricing Model for certain contracts under which home‐office overhead expenses must be recovered through FaRM is also presented. Once the FaRM Pricing Model has been implemented, contractors can make more intelligent pricing decisions. Instead of using a subjective markup, which may ignore the cash‐flow differences of various jobs, contractors using FaRM Pricing Model can bid lower on projects which are more attractive and become more competitive while satisfying their RRR. This should result in lower costs to owners. Conversely, by bidding higher on the less‐attractive jobs, contractors will still maintain their RRR should they obtain the contract.     

Large-scale simulations of crack–void and void–void plasticity in metallic fcc crystals under high strain rates

We have simulated the failure of three-dimensional fcc solids containing voids under mode one tension using molecular dynamics, simple interatomic potentials and a system comprising 15 million atoms. When a linear brittle crack front approaches a void, the void acts to impede the progress of the front by causing dislocation emission, thereby rendering the system ductile. When two voids are alone in the system, failure is via ductility with, first, dislocation loops being emitted from the void surfaces and, then, these loops interacting with one another to form.     

A new continuous-flow recycle microwave reactor for homogeneous and heterogeneous chemical reactions

A new continuous-flow recycle microwave reactor suitable for organic synthesis has been developed to handle 0.51 quantities of reagents. The apparatus, which is designed for laboratory use, operates at atmospheric pressure in open- or closed-loop mode. It is fitted with a temperature control system. We describe this novel reactor and illustrate its efficiency with examples of organic syntheses carried out using both homogeneous and heterogeneous reactions.     

Adaptive noise reduction using numerically stable fast recursive least squares algorithm

This paper is concerned with adaptive noise reduction based on the fast recursive least squares (FRLS) algorithm. It is well known that the fast recursive least squares (FRLS) algorithm suffers from numerical instability when operating under the effects of finite precision arithmetic. Several numerical solutions of stabilization were proposed in the case of stationary signals. In this work a new version of a numerically stable FRLS algorithm (NS‐FRLS) is proposed. The stability characteristics of this new stabilized algorithm are analysed. The analysis is based on a linear model for the errors in the states of the adaptive filter. Experimental results confirm the merits of adaptive filtering with the NS‐FRLS algorithm over optimum filtering using the solution provided by Wiener–Hopf equations. Copyright © 2006 John Wiley & Sons, Ltd.     

Processing, microstructure, properties and wear behavior of in situ synthesized TiB2 and TiC thick films on steel substrates

TiB₂ and TiC reinforced Fe matrix thick films (2 mm thickness) were produced through the synthesis reaction from Ti, C and FeB powders with varying porosity on the steel substrates. Powder technology was used as a processing method. The films and the substrates were sintered in a single step. TiB₂, TiC and Fe were detected in the films by X-ray diffraction analysis. The fact that no other reaction product was detected revealed the thermal stability of TiB₂ and TiC. The formation of secondary reaction products was inhibited during the reactive sintering. The films showed maximum strength of 163-466 MPa when sintered separately at 1350 °C. The strength of the films varied with their porosity. The films showed considerable bonding strength with the steel substrates. The delamination of the films from the steel substrates was observed at stress values from 454-781 MPa. The microstructure, fracture and delaminated surface morphologies were studied. The wear resistance against hardened high speed steel was studied in reciprocating sliding tests. The wear mechanisms were discussed by means of microscopical observation on the worn surfaces.     

The effect of ammonium sulphate—decabromobiphenyl oxide on the flammability of polyester/cotton blend

A 87.5:12.5 polyester/cotton blended fabric was treated with various concentrations of ammonium sulphate and decabromobiphenyl oxide (DBBO) as well as mixtures of the two additives. The flammability of the resulting systems was determined by the limiting oxygen index (LOI) method and their thermal decomposition by thermogravimetry. Ammonium sulphate was particularly less effective as a flame retardant than the DBBO. Decabromobiphenyl oxide acts in the gas phase to retard the flammability of the polyester while the inorganic salt acts in the condensed phase to decrease that of the cotton. A mechanism for the interaction of ammonium sulphate with cotton was suggested. When a mixture of the two additives containing a high percentage of the bromo-compound was used a significant increase in the LOI values was observed compared to one having the same total loading but containing a higher percentage of ammonium sulphate. This may be attributed to the stabilizing effect of the released ammonia on the intermediate species formed after the liberation of the bromine radicals from the DBBO.     

Assessment of a method for measuring serum thyroxine by radioimmunoassay, with use of polyethylene glycol precipitation

We assessed the efficacy of a new thyroxine radioimmunoassay kit (Abott) in which polyethylene glycol is used to separate bound from free hormone. Mean serum thyroxine was 88 +/- 15 (+/-SD) microgram/liter for 96 normal persons. Results for hypothyroid and hyperthyroid persons were clearly separated from those for normal individuals. Women taking oral contraceptive preparations showed variable increases in their serum thyroxine values. The coefficient of variation ranged from 1 to 3% within assay and from 5.4 to 11% among different assays. Excellent parallelism was demonstrated between thyroxine values estimated by this method and those obtained either by competitive protein binding or by a separate radioimmunoassay for the hormone.