22 resultados para ALKALINE MEDIUM

em Deakin Research Online - Australia


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In this work, LaMO3 and LaNi0.5M0.5O3 (M = Ni, Co, Fe, Mn and Cr) perovskite oxide electrocatalysts were synthesized by a combined ethylenediaminetetraacetic acid-citrate complexation technique and subsequent calcinations at 1000 °C in air. Their powder X-ray diffraction patterns demonstrate the formation of a specific crystalline structure for each composition. The catalytic property of these materials toward the oxygen reduction reaction (ORR) was studied in alkaline potassium hydroxide solution using the rotating disk and rotating ring-disk electrode techniques. Carbon is considered to be a crucial additive component because its addition into perovskite oxide leads to optimized ORR current density. For LaMO3 (M = Ni, Co, Fe, Mn and Cr)), in terms of the ORR current densities, the performance is enhanced in the order of LaCrO3, LaFeO3, LaNiO3, LaMnO3, and LaCoO3. For LaNi0.5M0.5O3, the ORR current performance is enhanced in the order of LaNi0.5Fe0.5O3, LaNi0.5Co0.5O3, LaNi0.5Cr0.5O3, and LaNi0.5Mn0.5O3. Overall, LaCoO3 demonstrates the best performance. Most notably, substituting half of the nickel with cobalt, iron, manganese, or chromium translates the ORR to a more positive onset potential, suggesting the beneficial catalytic effect of two transition metal cations with Mn as the most promising candidate. Koutecky–Levich analysis on the ORR current densities of all compositions indicates that the four-electron pathway is favored on these oxides, which are consistent with hydroperoxide ion formation of <2%.

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A new enzymeless glucose sensor has been fabricated via electrospinning technology and subsequent calcination. The morphology and structure of the as-prepared nanofibers have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The electrocatalytic oxidation of glucose in alkaline medium at nickel oxide modified glassy carbon electrodes has been investigated. The modified electrodes offer excellent electrocatalytic activity toward the glucose oxidation at low positive potential (0.3 V). Glucose has been determined chronoamperometrically at the surface of NiO nanofibers modified electrode in 0.5 mM NaOH. Under the optimized condition, the calibration curve is linear in the concentration range of 2 × 10−3 mM∼1 mM, and 1 mM∼9.5 mM. The detection limit (signal-to-noise 3) and response time are 3.394 × 10−6 M and 2 s, respectively. The NiO electrospun nanofibers is easy to prepare and feasible in economy. The modified electrode is steady and can be used repeatedly, so it is reasonable to expect its broad use in non-enzymatic glucose sensor.

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Replacement of precious Pt catalyst with cost-effective alternatives would be significantly beneficial for hydrogen production via electrocatalytic hydrogen evolution reaction (HER). All candidates thus far are exclusively metallic catalysts, which suffer inherent corrosion and oxidation susceptibility during acidic proton-exchange membrane electrolysis. Herein, based on theoretical predictions, we designed and synthesized nitrogen (N) and phosphorus (P) dual-doped graphene as a nonmetallic electrocatalyst for sustainable and efficient hydrogen production. The N and P heteroatoms could coactivate the adjacent C atom in the graphene matrix by affecting its valence orbital energy levels to induce a synergistically enhanced reactivity toward HER. As a result, the dual-doped graphene showed higher electrocatalytic HER activity than single-doped ones and comparable performance to some of the traditional metallic catalysts.

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It is believed that the recent emergence of electronic commerce (e-commerce) in the early '90s could provide different opportunities to small to medium-sized enterprises (SME's) in overcoming part of their technological, environmental, organizational, and managerial inadequacies. However, recent research portrays a gloomy picture about e-commerce uptake and use in SME's. Therefore, the implication here is twofold. Initially, there is a need to generate more e-commerce research that could penetrate much deeper into main impending issues pertaining to the SME’s in their potential uptake and use of e-commerce. On the other hand, e-commerce is characterized of being embryonic but growing very fast and fragmented across the different disciplines, which makes the task of capturing its different perspectives a very complex one. The preceding two implications represent the greatest challenge for researchers and professionals interested in undertaking e-commerce research in SME’s. In line with the above implications, the first objective of this research aims at capturing the different e-commerce perspectives from the SMEs' point of view, and the second objective aims at capturing the e-commerce perspective from the theoretical and the methodological point of view. Addressing the preceding implications in this research could shed some light into some of the gray areas in the e-commerce research in SMEs.

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Resistance to change has long been recognised as a critically important factor that can influence the success or otherwise of implementing any 'technological innovation. Information technology (IT) focused interventions, for example, business process re-engineering (BPR) and enterprise resource planning (ERP), are often quoted as examples of costly failures, with reported levels of dissatisfaction ·with strategic IT investments ranging from 20-70 percent and that employee resistance was to blame. The intention of this chapter is to rethink resistance. The author suggests that resistance remains to this day a complex, multifaceted phenomenon that continues to affect the outcomes of change, both negatively and positively. Although research has procured a solid understanding of resistance- and the benefits that can accrue to an organisation through its proper utilisation, it appears that the classical adversarial approach remains the dominant means ofmanaging resistance because such learning is not reflected in modern management techniques. The author concludes that as companies in every industry are now translating the power and possibilities 0/ e-business into strategic and operational realities, newapproaches in change managementare required to help organisations to understand the complex dynamics o/technological innovation and especially the multifaceted nature o/resistance.

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Grain refinement during and after hot isothermal deformation of a medium carbon steel has been investigated. The average austenite grain size decreased with an increase in strain for the hot deformed and recrystallised material, with refinement extending beyond the strain for the peak stress. A window of strain that corresponds to transition from classical static to metadynamic recrystallisation was observed in respect to the recrystallised material. Within this post-dynamic transition window the strain at which strain independent softening occurs was different for different volume fractions of the recrystallised material. This led to a new terminology corresponding to initiation of strain independent softening. For the alloy of this study, strain independent softening for the start of post-deformation recrystallisation occurred near the strain to the peak stress. The strain corresponding to complete metadynamic recrystallisation, which was defined as when all levels of recrystallisation were strain independent, was much greater than the strain for the peak stress.

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Quality methods in Australian industry gained much attention in the late 1980s and for most of the 1990s. In particular, quality methods such as quality systems and quality system certification had prominence, as Governments and large private sector firms attempted to improve their supply-chains. The aim of this paper is to demonstrate a rigorous and holistic approach to investigating the applicability of quality methods in Australian small and medium sized enterprises (SMEs). It describes the research framework developed to further investigate the impact of quality methods on Australian SMEs, and illustrates how the framework leads to a broader exploratory study.

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In New Zealand, small to medium-sized enterprises (SMEs) play a very important role in the economy by their contribution to both employment and also to gross domestic product. Addressing issues pertinent to SMEs is of paramount importance in driving this sector forward. Information Technology (IT) emerges as one main enabler for SMEs in automating their operations, seeking new opportunities and enhancing their strategic business positioning in local and international markets. However, the dynamic nature of IT and inability of SMEs, due to problems inherent in their size and structure, makes it difficult for them to take appropriate decisions to benefit from the IT technologies. The advent of eCommerce (EC) has only compounded this problem. One way out of this complex situation is to outsource the IT and EC technology requirements by the SMEs. This study endeavours to identify the pattern of IT and EC outsourcing issues of SMEs within New Zealand. It reveals that the main driver for IT outsourcing is access to expertise and used mainly for maintenance purposes only. The study also identifies the problems in IT outsourcing and makes suggestions for further research in this crucial sector.

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This paper delivers the findings from a study conducted to investigate Australian SMEs and e-business security. The study established the attitudes and concerns of a sample of Australian Small and Medium-sized Enterprises (SMEs) towards the use of e-business within their operational environment using the members of the Geelong Chamber of Commerce as a base for survey participants. The results focus on e-business security and identifying mechanisms that SMEs use to safeguard their e-business systems.