Several behavioral assays are currently used for high-throughput neurophenotyping and screening of genetic mutations and psychotropic drugs in zebrafish (Danio rerio). In this protocol, we describe a battery of two assays to characterize anxiety-related behavioral and endocrine phenotypes in adult zebrafish. Here, we detail how to use the 'novel tank' test to assess behavioral indices of anxiety (including reduced exploration, increased freezing behavior and erratic movement), which are quantifiable using manual registration and computer-aided video-tracking analyses. In addition, we describe how to analyze whole-body zebrafish cortisol concentrations that correspond to their behavior in the novel tank test. This protocol is an easy, inexpensive and effective alternative to other methods of measuring stress responses in zebrafish, thus enabling the rapid acquisition and analysis of large amounts of data. As will be shown here, fish anxiety-like behavior can be either attenuated or exaggerated depending on stress or drug exposure, with cortisol levels generally expected to parallel anxiety behaviors. This protocol can be completed over the course of 2 d, with a variable testing duration depending on the number of fish used.

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Copper and nickel are codeposited by pulse and reverse-pulse plating on a rotating cylinder cathode from a citrate bath. Polarization data for copper and nickel as well as potential transients during pulse and reverse-pulse current experiments show that displacement reactions may occur during the pulse off-time or pulse-reversal time. A mathematical model which includes this effect is developed to predict the composition of electrodeposited alloys. The model shows that copper deposits at the mass-transfer limiting current throughout the pulse-cycle while nickel is alternately deposited and dissolved during the pulse on-time and off-time (or reversal time). The alloy composition is governed by pulse parameters and the diffusion limiting current for copper deposition.Due to the importance of pulsed currents in alloy electrodeposition, 1-4 a variety of investigations have focused on determining the fundamental relationships between applied pulse-parameters, governing physical phenomena (such as reaction kinetics and hydrodynamics), and the composition of the deposit. Verbrugge and Tobias~'6 proposed a theoretical model which could be used to calculate current-voltage relationships, metal ion concentration at the cathode, and deposit composition during the electroplating of a multicomponent alloy using periodic currents. Their model included the equation of convective diffusion to describe liquid-phase mass transfer at a rotating disk, Butler-Volmer expressions to calculate the rate of chargetransfer reactions at the electrode surface, and activities of individual metals in the solid-state to compute the composition of the deposit. They investigated numerically the effect of hydrodynamics, reactant concentration, reversible potentials, and solid-state activity on the deposit composition of a Cd-Te alloy. Pesco and Cheh 7 used a treatment similar to that of Verbrugge and Tobias, except that solidstate activities were neglected. They computed the composition of Pb-Sn alloys plated at a rotating disk electrode under mixed mass-transfer and kinetic control. Ruffoni and Landolt ~ investigated experimentally the variation in the composition of Au-Cu-Cd alloys as a function of applied pulse parameters and hydrodynamics. The results were compared with the prediction of a mathematical model which took into account the kinetic behavior of the three alloy components and hydrogen. 9 More recently White and co-workers ~~ have presented a theoretical model which includes the effects of migration on ion transport and of addition agents on reaction kinetics of the depositing metals.During pulse-plating of binary a11oys, the applied current is cycled between a high and a low or zero value. At high current density, both alloying dements are reduced at the cathode, but at low current density or at the opencircuit potential the less noble metal can be selectively dissolved or displaced from the alloy by the more noble one. n46 The numerical analysis of Verbrugge and Tobias 5 has already indicated that the more noble component may contin...

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Micro- and nano-scale devices are used in electronics, micro-electro- mechanical, bio-analytical and medical components. An essential step for the fabrication of such small scale devices is photolithography. Photolithography requires a master mask to transfer micrometre or sub-micrometre scale patterns onto a substrate. The requirement of a physical, rigid mask can impede progress in applications which require rapid prototyping, flexible substrates, multiple alignment and 3D fabrication. Alternative technologies, which do not require the use of a physical mask, are suitable for these applications. In this paper mask-less methods of micro- and nano-scale fabrication have been discussed. The most common technique, which is the laser direct imaging (LDI), technique has been applied to fabricate micrometre scale structures on printed circuit boards, glass and epoxy. LDI can be combined with chemical methods to deposit metals, inorganic materials as well as some organic entities at the micrometre scale. Inkjet technology can be used to fabricate micrometre patterns of etch resists, organic transistors as well as arrays for bioanalysis. Electrohydrodynamic atomisation is used to fabricate micrometre scale ceramic features. Electrochemical methodologies offer a variety of technical solutions for micro- and nano-fabrication owing to the fact that electron charge transfer can be constrained to a solid–liquid interface. Electrochemical printing is an adaptation of inkjet printing which can be used for rapid prototyping of metallic circuits. Micro-machining using nano-second voltage pulses have been used to fabricate high precision features on metals and semiconductors. Optimisation of reactor, electrochemistry and fluid flow (EnFACE) has also been employed to transfer micrometre scale patterns on a copper substrate. Nano-scale features have been fabricated by using specialised tools such as scanning tunnelling microscopy, atomic force microscopy and focused ion beam. The methodologies adopted for nano-fabrication have analogies with the micrometre scale patterning methods. Currently, the resolution of mask-less techniques is lower than that of lithographic methods using a physical mask. However, in future, hybridisation or combination of the mask-less methods could lead to high resolution and higher precision micro- and nano-scale patterning methods.

An analysis of the speciation of gold plating solutions containing sulfite and thiosulfate as complexing agents has been performed. In the case of gold sulfite baths, it was found that the observed stability and electrochemical behavior were inconsistent with the commonly assumed stability constants of ␤ = 10 10 for the Au͑SO 3 ͒ 2 3− species. The data are, however, consistent with a much larger stability constant of ␤ = 10 27 . In gold plating baths containing sulfite and thiosulfate ligands, the speciation model predicts that the dominant species at neutral or basic are mixed complexes of the form Au͑S 2 O 3 ͒͑SO 3 ͒ 3− and Au͑S 2 O 3 ͒͑SO 3 ͒ 2 5− . The thiosulfate complex Au͑S 2 O 3 ͒ 2 3− is only dominant under acidic conditions. It is shown that the electrodeposition characteristics reported in many studies can be interpreted in terms of the existence of such mixed ligand complexes. Finally, the effect of the stability of various gold plating solutions on colloidal gold formation has been explored. For free-standing solutions, decomposition is more likely to occur via the disproportionation of Au͑I͒ species such as AuOH, Au͑OH͒ 2 − , and AuCl 2 − rather than free aurous ions. The stability of gold baths during electrodeposition is mainly influenced by the formation of dithionite ions which reduce Au͑I͒ complexes to form colloidal gold.

The stability of citrate electrolytes for the electrodeposition of copper-nickel alloys and multilayers has been investigated. It was found that electrolytes operating at pH 4 are unstable due to the formation of an insoluble citrate complex. This complex had previously been thought to be copper citrate dihydrate, Cu2C6H4O7'2H,O, but elemental analysis of the precipitate revealed it to be a heteronuclear copper-nickel citrate complex. Calculations of the distribution of citrate species in a typical plating solution was undertaken to identify experimental conditions under which the insoluble citrate complex is not formed. These studies indicate that increasing the pH of the citrate solution from 4 to 6 should produce a stable electrolyte. Experimental studies show that the electrolytes at pH 6 are stable for periods of several weeks, in agreement with the predictions of the speciation calculations. The stable citrate electrolytes were used to deposit Cu-Ni alloys. It was found that alloys could be deposited from these electrolytes with almost 100% current efficiency and with a morphology and composition comparable to those.obtained from the unstable citrate electrolytes.