Sodium silicate as alternative to liming-reduced aluminium toxicity for Atlantic salmon (Salmo salar L.) in unstable mixing zones

When acid aluminium (Al) rich water is limed, unstable mixing zones are formed until equilibrium is reached. In such mixing zones transient high molecular mass positively charged Al-species (HMM Al(i)) being extremely gill reactive are produced, causing toxic effects in fish. The transient HMM Al(i)-species are formed due to hydrolysis and polymerization of low molecular positively charged Al-species (LMM Al(i)), e.g. initiated by liming and the subsequent increase in pH. To counteract the toxicity of transient Al polymers in such mixing zones, sodium silicate, forming non-toxic hydroxyaluminosilicate (HAS) complexes, can be used as alternative to liming. In the present work the effect of sodium silicate on polymerization of LMM Al(i) in unstable mixing zones and subsequent gill reactivity and mortality of fish was compared to results obtained from liming. Diluted sodium silicate (<1.5 g l(-1)) and lime slurry (Ca(OH)(2)), respectively, were continually added to acidified Al-rich water in six different channel-tank systems, to obtain mixing zones with pH 5.9, 6.0 and 6.4, respectively. Utilising in situ size and charge fractionation techniques and following the exposure of Atlantic presmolt (Salmo salar L.) kept in cages at defined stations along the channel-tank systems, changes of Al-species in the mixing zones, the gill reactivity of Al-species and thus Al toxicity could be followed downstream the confluences (time of reaction after mixing: 1-100 min). By increasing the pH of the acid water to 6.0 or 6.4 by sodium silicate, the detoxification of Al was faster than using lime. Using sodium silicate, the transformation of LMM Al(i), the formation of HMM Al(i), the Al deposition in fish gills and fish mortality were lower than using lime. The formation of neutral LMM Al-species (Al(o)) was, however, higher and the formation of colloidal Al-species (Al(c)) lower in the presence of silicate compared to lime. Furthermore, the Al deposition in fish gills and fish mortality decreased by increasing concentration of sodium silicate dosed. Thus, sodium silicate is a good alternative to liming, and under certain circumstances when aging of water may represent a problem (e.g. aquaculture) sodium silicate should be the preferred agent.     

A simple back-of-the-envelope test for self-citations using Google Scholar author profiles

Scientometrics - The issue of self-citation has received much attention in academia. Widely used and accessible tools such as Google Scholar do not provide information about self-citations....     

THE SWISS NEMA CIPHER MACHINE

The Enigma is probably the most well known wired wheel cipher machine. The NEMA is a cipher machine developed during World War II by the Swiss Army. It is designed on the same principle as the Enigma but with particular emphasis on overcoming some of its weak features. It was declassified by the Swiss Authorities in 1992. This paper describes its mechanism and the way in which it operates, so that it may be more widely known to cryptology researchers.     

Improved electrode systems for reverse electro-dialysis and electro-dialysis

Reverse Electro-Dialysis, RED, is an electrochemical technique to extract work by mixing aqueous solutions of different salinities. Electro-Dialysis, ED, is an electrochemical technique to extract potable water from seawater. Both RED and ED typically employs noble metal oxide catalysts in the conversion between electronic current and ionic current. By testing several different electrode materials and red-ox salts, this paper demonstrates that these electrochemical reactions are controlled by mass transfer in the electrolyte rather than by the electrocatalytic properties of the electrode material. By comparing two different carbon materials and standard noble metal oxides, we show, for two red-ox salts, that the electrochemical performances of the inexpensive and expensive materials are similar. Relatively inexpensive graphite along with environmentally benign FeCl₂ and FeCl₃ in moderate concentrations was demonstrated to lower the electrode concentration overpotential.     

Automatic Optical Inspection of Solder Ball Burn Defects on Head Gimbal Assembly

Journal of Failure Analysis and Prevention - The detection of low-quality solder joints in hard disk drive manufacturing is a time-consuming, error-prone and costly process that is often performed...     

Impedance study of methanol oxidation on platinum electrodes

Methanol oxidation on Pt electrodes is studied by ac voltammetry. Data from voltammograms at frequencies from 0.5 Hz to 20 kHz are assembled into electrochemical impedance spectra and analysed using equivalent circuits. Inductive behavior and negative relaxation times are attributed to nucleation and growth behavior. The rate-determining step is proposed to be the reaction of adsorbed CO and OH at the edge of islands of OH, with competition between OH and CO adsorption for the released reaction sites.     

Characterization of all Six Mono -Methylchrysenes by NMR and MS

Complete assignment of the 1 H and 13 C resonances of the methylchrysenes ( 1 - 6 ) were accomplished using 1D and 2D NMR techniques. Shift increments were calculated for the six mono -methyl isomers, showing the similarity of the positions 1 and 6, 2 and 3, and 4 and 5 in these systems. Simulation of the 13 C NMR spectra gave large differences in chemical shifts compared to the experimental values. The mass spectra of chrysene ( 7 ) with methyl substituent in all six possible positions were similar and very simple, containing little structural information.