Library co-operation and ICT in the UK: an overview

Tedd, L.A. (2003). Library co-operation and ICT in the UK: an overview. Information Services and Use, 23(4), 199-210

Wetting and Reaction of Sn-2.8Ag-0.5Cu-1.0Bi Solder with Cu and Ni Substrates

The wettability of newly developed Sn-2.8Ag-0.5Cu-1.0Bi lead-free solder on Cu and Ni substrates was assessed through the wetting balance tests. The wettability assessment parameters such as contact angle (ϑc) and maximum wetting force (Fw) were documented for three solder bath temperatures with three commercial fluxes, namely, no-clean (NC), nonactivated (R), and water-soluble organic acid flux (WS). It was found that the lead-free Sn-2.8Ag-0.5Cu-1.0Bi solder exhibited less wetting force, i.e., poorer wettability, than the conventional Sn-37Pb solder for all flux types and solder bath temperatures. The wettability of Sn-2.8Ag-0.5Cu-1.0Bi lead-free solder on Cu substrate was much higher than that on Ni substrate. Nonwetting for Sn-2.8Ag-0.5Cu-1.0Bi and Sn-Pb solders on Ni substrate occurred when R-type flux was used. A model was built and simulations were performed for the wetting balance test. The simulation results were found very close to the experimental results. It was also observed that larger values of immersion depth resulted in a decrease of the wetting force and corresponding meniscus height, whereas the increase in substrate perimeter enhanced the wettability. The wetting reactions between the solder and Cu/Ni substrates were also investigated, and it was found that Cu atoms diffused into the solder through the intermetallic compounds (IMCs) much faster than did the Ni atoms. Rapid formation of IMCs inhibited the wettability of Sn-2.8Ag-0.5Cu-1.0Bi solder compared to the Sn-Pb solder.

Comparative wetting behavior of Sn-0.7Cu and Sn-0.7Cu-0.3Ni solders on Cu and Ni substrates

Electronic packaging industries are now in great challenge to find a suitable lead-free solder as an interconnection material to replace the conventional SnPb solders. Many solders such as SnCu, SnAg, SnAgCu, SnZn, SnBi have already been proposed as the replacement but none of them has reached the physical and metallurgical properties similar to the SnPb solder. However, wetting is one of the basic problems that make the lead-free solder inferior as compared to the SnPb solder. Therefore, alloying with the help of third, fourth or fifth element is the researchers' interest to improve the wetting behavior of lead-free solders. This paper describes the comparative wetting behavior of Sn-0.7Cu and Sn-0.7Cu-0.3Ni solders on Cu and Ni substrates. Wetting balance tests were performed to assess the wetting behaviors. Three different commercial fluxes namely no-clean (NC), non-activated (R) and water soluble organic acid (WS)fluxes were used to assess the wettability for three solder bath temperatures. It was found that Sn0.7Cu-03Ni solder exhibits better wettability on Cu substrate for NC and WS fluxes whereas reverse results were found for R-type flux. In the case of Ni substrate, Sn-0.7Cu-0.3Ni solder showed better wetting behavior compared to the well-known Sn-0.7Cu solder. Among the three fluxes, R-type flux showed the worst performance. Very large contact angles were documented for both solders with this flux. Higher solder bath temperature lowered the contact angles, increased the wetting forces and enhanced the wettability. Computer modeling of wetting balance test revealed that both the wetting force and meniscus height are inversely proportional to the contact angles. Modeling results also reveal that increase in solder bath depths and radiuses do not affect significantly on the wetting behavior.

Effect of adding 0.3 wt% Ni into the Sn–0.7 wt%Cu solder: part I: wetting behavior on Cu and Ni substrates

Comparative wetting behavior of Sn-0.7Cu and Sn-0.7Cu-0.3Ni solders on Cu and Ni substrates were assessed through the wetting balance test. No-clean (NC), non-activated (R) and water soluble organic acid (WS) fluxes were used to assess the wetting behavior for three different solder bath temperatures of 255, 275 and 295 °C. Experimental results unveiled that adding of 0.3 wt% Ni into Sn-0.7Cu solder can improve the wetting on Cu substrate when NC and WS fluxes are used. However, such addition of Ni did not improve the wetting of Sn-0.7Cu solder for R-type flux. In the case of Ni substrate, addition of Ni helped to improve the wetting for all three types of fluxes as higher wetting forces were documented for Sn-0.7Cu-0.3Ni solder compared to the Sn-0.7Cu solder. Among the fluxes, worst performance was observed for R-type flux. Very large contact angles were recorded for both solders with this kind of flux. Experimental results also revealed that higher solder bath temperature played an important role to lower the contact angle, to increase the wetting force and to enhance the wetting. Computer modeling of wetting balance test also revealed that both the wetting force and meniscus height are inversely proportional to the contact angles. Besides, solder bath depth and radius do not affect significantly on the wetting behavior.

Microwave mediated reduction of heterocycle and fluorine containing nitroaromatics with Mo(CO)(6) and DBU

Heterocycle containing nitroaromatics were reduced by Mo(CO)(6) and DBU in EtOH under microwave irradiation within 15 min. Under the same conditions, 4-fluoronitrobenzene was reduced to 4-fluoroaniline, whereas 2-chloro-1-fluoro-4-nitrobenzene afforded a mixture of 3-chloro-4-fluoroaniline and 3-chloro-4-ethoxyaniline. The extent of the competing SNAr/reduction process could be influenced by the nature of the solvent, with t-BuOH the inert solvent of choice. The latter was used as solvent for SNAr/reductions of 2-chloro-1-fluoro-4-nitrobenzene with S-nucleophiles to yield 3-chloro-4-mercaptoanilines. Crown Copyright (c) 2008 Published by Elsevier Ltd. All rights reserved.

Shifting Thresholds, Contested Meanings: Governance, Cross-border Co-operation and the Ulster Unionist Identity

Cross-border (North/South) co-operation between the Republic of Ireland and Northern Ireland was an indelible feature of the form of governance provided by the Belfast Good Friday Agreement (1998). Previous efforts to establish North/South co-operation had all foundered but the establishment and initial operation of the Agreement's cross-border institutions proved to be uncontroversial. However, during its implementation, other areas of the Agreement gave Ulster unionists more pressing cause for concern. These areas of concern included the release of paramilitary prisoners, police reform, the 'decommissioning' of Irish Republican Army (IRA) weaponry, and the unionist perception that the 'Britishness of Northern Ireland' was being actively eroded. These concerns served to emphasise and strengthen political and cultural borders between communities at a regional and local level within Northern Ireland. They also threatened the pro-Agreement unionists' contestation of unionist ideological orthodoxy, a contestation that was undertaken in an attempt to adapt the Ulster unionist identity to the shifting thresholds of the state.

Dynamic, in situ optical, magnetic and magneto-optical monitoring of the growth of Co/Au and Pd/Co/Au multilayer systems

The growth of magnetron sputtered Co/Au and Pd/Co/Au superlattices on Au and Pd buffer layers, deposited onto glass substrates, has been monitored optically and magneto-optically in real time, using rotating analyser ellipsometry and Kerr polarimetry, at a wavelength of 633 nm. The magneto-optical traces, combined with ex situ and in situ hysteresis loops, provide a detailed and informative fingerprint of the optical and magnetic properties of the films as they evolve during growth. For Co/Au, oscillations in the polar magneto-optical effect developed during the deposition of An overlayers on Co and these may be attributed to quantum well states. However, the hysteresis measurements show that the magnetic field required to maintain saturation magnetization throughout the experiment was larger than available in situ, introducing a degree of confusion concerning the interpretation of the data. This problem was overcome by the incorporation of Pd layers into the Co/Au structure, thereby eliminating variation in magnetic orientation during growth of the Au layers as a contributory factor to the observations.

Energy levels and radiative rates for transitions in Mg-like iron, cobalt and nickel

Energy levels and radiative rates for electric dipole (E1) transitions among the lowest 141 levels of the (IS2 2s(2) 2P(6)) 3l(2) , 3l3l', and 3l4l configurations of Fe XV, Co XVI, and Ni XVII are calculated through the CIV3 code using extensive configuration-interact ion (CI) wavefunctions. The important relativistic effects are included through the Breit-Pauli approximation. In order to keep the calculated energy splittings close to the experimental values, we have made small adjustments to the diagonal elements of the Hamiltonian matrices. The energy levels, including their orderings, are in excellent agreement with the available experimental results for all three ions. However, experimental energies are only available for a few levels. Since mixing among some levels is found to be very strong, it becomes difficult to identify these uniquely. Additionally, some discrepancies with other theoretical work (particularly for Ni XVII) are very large. Therefore, in order to confirm the level ordering as well as to assess the accuracy of energy levels and radiative rates, we have performed two other independent calculations using the GRASP and FAC codes. These codes are fully relativistic, but the CI in the calculations is limited to the basic (minimum) configurations only. This enables us to assess the importance of including elaborate Cl for moderately charged ions. Additionally, we report results for electric quadrupole (E2), magnetic dipole (MI), and magnetic quadrupole (M2) transitions, and list lifetimes for all levels. Comparisons are made with other available experimental and theoretical results, and the accuracy of the present results is assessed. (c) 2007 Elsevier Inc. All rights reserved.

CO oxidation and NO reduction on metal surfaces: density functional theory investigations

This article reviews the accumulated theoretical results, in particular density functional theory calculations, on two catalytic processes, CO oxidation and NO reduction on metal surfaces. Owing to their importance in automotive emission control, these two reactions have generated a lot of interest in the last 20 years. Here the pathways and energetics of the involved elementary reactions under different catalytic conditions are described in detail and the understanding of the reactions is generalized. It is concluded that density functional theory calculations can be applied to catalysis to elucidate mechanisms of complex surface reactions and to understand the electronic structure of chemical processes in general. The achieved molecular knowledge of chemical reactions is certainly beneficial to new catalyst design.

Adsorption characteristics of Cu and Ni on Irish peat moss

Peat has been widely used as a low cost adsorbent to remove a variety of materials including organic compounds and heavy metals from water. Various functional groups in lignin allow such compounds to bind on active sites of peat. The adsorption of Cu²⁺ and Ni²⁺ from aqueous solutions on Irish peat moss was studied both as a pure ion and from their binary mixtures under both equilibrium and dynamic conditions in the concentration range of 5–100 mg/L. The pH of the solutions containing either Cu²⁺ or Ni²⁺ was varied over a range of 2–8. The adsorption of Cu²⁺ and Ni⁺² on peat was found to be pH dependent. The adsorption data could be fitted to a two-site Langmuir adsorption isotherm and the maximum adsorption capacity of peat was determined to be 17.6 mg/g for Cu²⁺ and 14.5 mg/g for Ni²⁺ at 298 K when the initial concentration for both Cu²⁺ and Ni²⁺ was 100 mg/L, and the pH of the solution was 4.0 and 4.5, respectively. Column studies were conducted to generate breakthrough data for both pure component and binary mixtures of copper and nickel. Desorption experiments showed that 2 mM EDTA solution could be used to remove all of the adsorbed copper and nickel from the bed.

The effects of the specific adsorption of anion on the reactivity of the Ru(0001) surface towards CO adsorption and oxidation: in situ FTIRS studies

The dynamics of adsorption and oxidation of CO on Ru(0001) electrode in sulfuric acid solution have been studied using in situ FTIR spectroscopy under potential control and at open circuit, the latter at 20 and 55 degrees C. The in situ IR data show clearly that the bisulfate anion adsorbs on the Ru(0001) surface over the potential range from -200 mV to 350 mV (vs. Ag/AgCl) at 20 degrees C in the absence and presence of adsorbed CO; however, increasing the temperature to 55 degrees C and/ or increasing the concentration of dissolved O-2 reduces the bisulfate adsorption. The formation of surface (hydro-) oxide at higher potentials replaces the bisulfate adsorbates. Both linear (COL) and three-fold hollow bonded CO (COH) adsorbates were produced following CO adsorption at Ru(0001) in H2SO4, as was observed in our previous studies in HClO4. However, the amount of adsorbed CO observed in H2SO4 was ca. 10% less than that in HClO4; in addition, the COL and COH frequencies were higher in H2SO4, and the onset potential for COads oxidation 25 mV lower. These new results are interpreted in terms of a model in which the adsorbed bisulfate weakens the CO adlayer, allowing the active Ru oxide layer to form at lower potentials. Significantly different results were observed at open circuit in H2SO4 compared both to the data under potential control and to our earlier data in HClO4, and these observations were rationalized in terms of the adsorbed HSO4- anions (pre-adsorbed at -200 mV) inhibiting the oxidation of the surface at open circuit (after stepping from the initial potential of -200 mV), as the latter was no longer driven by the imposed electrochemical potential but via chemical oxidation by trace dissolved O-2. Results from experiments at open circuit at 55 degrees C and using oxygen-saturated H2SO4 supported this model. The difference in Ru surface chemistry between imposed electrochemical control and chemical control has potential implications with respect to fuel cell electrocatalysis.