Ultrasmooth gold thin films by self-limiting galvanic displacement on silicon

Galvanic displacement (GD), a type of electroless deposition, has been used to obtain ultrasmooth gold thin films on silicon <111>. The novel aspect of the method presented herein is the absence of fluoride ions in the liquid phase, and its principal advantage when compared to previous efforts is that the process is inherently self-limiting. The self-limiting factor is due to the fact that in the absence of fluorinated species, no silicon oxide is removed during the process. Thus, the maximum gold film thickness is achieved when elemental silicon is no longer available once the surface is oxidized completely during the galvanic displacement process. X-ray photoelectron spectroscopy has been used as a tool for thickness measurement, using the gold to silicon ratio as an analytical signal. Three gold plating solutions with different concentrations of KAuCl? (2, 0.2, and 0.02 mM) have been used to obtain information about the formation rate of the gold film. This XPS analysis demonstrates the formation of gold films to a maximum thickness of ～3.5 ?. Atomic force microscopy is used to confirm surface smoothness, suggesting that the monolayer growth does not follow the Volmer-Weber growth mode, in contrast to the GD process from aqueous conditions with fluorinated species.     

Green information systems use in social enterprise: the case of a community-led eco-localization website in the West Midlands region of the UK

This study examines the intention of environmentally-oriented social enterprises to continue using Green IS (an eco-localization website here) in Herefordshire located in the West Midlands region of the United Kingdom. The Herefordshire Greenlinks (HGL) Association is a local business community that operates primarily through the HGL Website in order to help local social enterprises find and trade local eco-friendly goods and services. It is an example of a “market-based” approach to solving social and environmental issues that is inspired by a bottom-up view of community development and eco-localization. Based on the theory of uses and gratification of media use and the new environmental paradigm, we propose a research model that outlines the various factors contributing to intention to continue using an eco-localization website. The research model and its associated hypotheses were empirically tested using a dataset generated from a survey of 83 small social enterprises. The results demonstrate the importance of three different types of gratification – content, social and performance gratification as well as users’ environmental concerns in determining the intention to continue using an eco-localization website. This study contributes to the Green IS literature by extending research to the social sector environment, and it also provides practical insight for designers of such community-led eco-localization websites.     

Synthesis of gold pearlescent pigment via heat treatment of mica

Pearlescent pigments are widely used to decorate ceramic tableware and architectural ceramics. Coating of mica with high-refractive metal oxides such as titanium oxide is one of the most important synthesis methods of these pigments. However, this process is expensive and long. Moreover, because of the complexity of the process, it is difficult to control and obtain consistent color. This depends on the thickness of the deposited thin film layer. In this study, a low-cost and easy method is proposed to synthesize gold pearlescent pigment. In this case, bulk mica (phlogopite) is heat-treated at appropriate temperatures, determined from related differential thermal analysis (DTA) profiles. Then, the obtained materials are milled for about 2 h and sieved in the 20–60 μm range. X-ray diffraction (XRD) and goniospectrophotometery are used for characterization of the obtained pigment. XRD results showed a few changes in related patterns of the primary sample. In this case, a part of the initial phase of phlogopite was changed to Mg₂SiO₄ (forsterite) and K₂MgSi₅O₁₂ (leucite). Goniospectrophotometer results demonstrated the highest reflectance in the 560–570 nm range (yellow color), and showed a satisfactory level of brightness and lightness of the obtained gold color.     

Project governance and stakeholders: a literature review

Despite the importance of stakeholders in project governance, project management literature lacks from an inclusive framework which defines the roles, relationships and positions of internal and external stakeholders inside and outside of the organization's governance structure. This paper has the purpose to report a review on project governance literature to draw attention to the context within which the stakeholders are positioned, to extract their roles and relationships inside and outside of the organization and to develop new avenues for research regarding stakeholders in project governance. The conducted thematic analysis reveals that there are three contexts influencing organization's approaches towards stakeholders: success, megaprojects and ethics. The developed conceptual framework illustrates that organizations are in direct contact with external stakeholders at the organizational level and project level. Strategic decisions made at the organizational level are operationalised at the portfolio level and influence the approach towards external stakeholders at the project level. Considering the lack of theories to support general doctrine of stakeholder theory, this research suggests that future governance researchers adopt a broader view in selection of theoretical lenses in order to include the social and psychological aspects of the management of external stakeholders.     

A simple soft lithographic nanopatterning of gold on gallium arsenide via galvanic displacement

Nanoscale patterning of gold layers on GaAs substrate is demonstrated using a combination of soft lithographic molding and galvanic displacement deposition. First, an electroless deposition method has been developed to plate gold on GaAs with ease and cost-effectiveness. The electroless metallization process is performed by dipping the GaAs substrates into a gold salt solution without any reducing agents or additives. The deposition proceeds via galvanic displacement in which gold ions in the aqueous solution are reduced by electrons arising from the GaAs substrate itself. The deposition rate, surface morphology and adhesion property can be modulated by the plating parameters such as the choice of acids and the immersion time. Second, soft lithographic patterning of nanodots, nanorings, and nanolines are demonstrated on GaAs substrates with hard-polydimethylsiloxane (h-PDMS) mold and plasma etching. This method can be easily applied to the metallization and nanopatterning of gold on GaAs surfaces.     

Wall Decay Coefficient Estimation in a Real-Life Drinking Water Distribution Network

Water Resources Management - Injection of chlorine as a disinfectant and the correct prediction of the residual amount in water distribution networks are key points and important principles in the...     

Simultaneous determination of pyruvate and acetate levels in xanthan biopolymer by infrared spectroscopy: effect of spectral pre-processing for solid-state analysis

A rapid, direct, and reagent-free procedure based on solid-state Fourier transform infrared spectroscopy (FT-IR) coupled with partial least squares (PLS) data analysis has been developed for simultaneous determination of pyruvate and acetate levels in a microbial xanthan biopolymer. The influences of various spectral pre-processing procedures were studied in order to eliminate effects caused by sample preparation. It was determined that the combination of first derivative and orthogonal signal correction pre-processing contributes to a significant increase in the predictive performance of PLS-1 regression models. By employing the wavenumber region 1320–1350 cm⁻¹ for pyruvate determination and 1500–1600 cm⁻¹ for acetate determination, the root mean square error of cross-validation (RMSECV) for pyruvate and acetate contents were obtained 0.13% and 0.29% w/w, respectively. Results of the proposed procedure for different real samples and those obtained by their reference methods were compared.     

Tribological Challenges in Micromechanical Systems

Despite much progress in surface micromachining technology, adhesion, friction and wear remain key issues, severely limiting the realization and reliability of many microelectromechanical systems (MEMS) devices. In this article, we focus on the use of molecularly thin organic films as release and anti-stiction coatings for MEMS. The various classes of organic films explored for MEMS are reviewed here, followed by a discussion of the current limitations and areas for improvements for this coating technology.     

Adhesion Characteristics of PDMS Surfaces During Repeated Pull‐Off Force Measurements

To mimic the adhesive effects of gecko toes, artificial surfaces have been manufactured recently using polydimethylsiloxanes (PDMS). However, the effects of repeated contacts on the adhesive properties remain largely unexplored. In this paper we report on the effect of repeated pull‐off force measurements on the adhesion behavior of PDMS (polymer kit Sylgard 184, Dow Corning) tested with a borosilicate glass probe. A decrease in pull‐off force with increase in number of test cycles is found until a plateau is reached. The initial value and the rate of change in pull‐off force strongly depend on the sample preparation procedure, including curing time and cross‐linking. It is proposed that the behavior is due to steady coverage of the probe with free oligomers. The results are crucial for developing reusable, durable, and residue‐free bioinspired adhesives.