98 resultados para TERTIARY-AMINES

em Deakin Research Online - Australia


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The reaction of tris(2,2’-bipyridyl)ruthenium(III) (Ru(bipy) 33+) with various analytes to generate chemiluminescence has been well documented. This investigation sought to undertake a chemiluminometic study of the reactions of Ru(bipy) 33+ with selected Papaver Somniferum alkaloids and specifically synthesised phenethylamines. The investigation, based on a kinetic study, primarily addressed the effect of varying reaction conditions (pH) on Ru(bipy) 33+ chemiluminescence production. To monitor these reactions, a batch chemiluminometer was specifically designed, fabricated and automated to conduct an extensive study on the selected compounds of interest. The instrumentation incorporated a custom built reaction cell and comprised an ‘on-line’ sample preparation system with which calibration standards could be automatically prepared. The instrumentation provided both time-independent (peak area) and time-dependent (kinetic profile) information. A novel approach to the stabilisation of Ru(bipy) 33+ as a chemiluminescencent reagent was also investigated and a recirculating system was employed with the batch chemiluminometer to provide a stable supply of Ru(bipy) 33+. Codeine, thebaine and 6-methoxy-codeine were the Papaver Somniferum alkaloids selected for this study and several N-methylated and N,N-dimethylated phenethylamines and methoxy-substituted phenetheylamines were also synthesised to investigate the affect of pH on the chemiluminescence emission efficiency. The versatility of the batch chemiluminometer facilitated the kinetic study of numerous analytes over a broad pH range. The exemplary performance of the chemiluminometer as an analytical instrument, was demonstrated by the calibration functions, based on peak area data, which exhibited excellent linearity and sensitivity. The estimated detection limits (3s) for the selected alkaloids were in the range 2 x 10-9 M to 7 x 10-9 at pH 5.0 and above, which compared favourably to detection limits for the same compounds determined using FIA. Relative standard deviations (n=5) for peak areas ranged between 1% to 5% with a mean of 3.1% for all calibration standards above 2.5 x 10-8 M. Correlation between concentration and peak area, irrespective of pH and analyte was excellent, with all but two calibration functions having r-squared values greater than 0.990. The analytical figures of merit exemplified the precision and robustness of the reagent delivery and ‘on-line’ sample preparation, as well as the sensitivity of the system. The employment of the chemiluminometer for the measurement of total chemiluminescence emission (peak area) was in itself a feasible analytical technique, which generated highly reproducible and consistent data. Excellent analytical figures of merit, based on peak area, were similarly achieved for the phenethylamines. The effects of analyte structure on chemiluminescence activity was also investigated for the alkaloids and the phenethylamines. Subtle structural variations between the three alkaloids resulted in either a moderately reduced or enhanced total emission that was two or three fold difference only. A significant difference in reaction kinetics was observed between thebaine and codeine/6-methoxy-codeine, which was dependent upon pH. The time-dependent data, namely the observed rate constants for the initial rise in intensity and for the subsequent decay rate, were obtained by fitting a mathematical function (based on the postulated reaction mechanism) to the raw data. The determination of these rate constants for chemiluminescence reactions highlighted the feasibility for utilising such measurements for quantitative analytical applications. The kinetic data were used to discriminate between analyte responses in order to determine the concentrations of individual analytes in a binary mixture. A preliminary, multi-component investigation performed on a binary mixture of codeine and 6-methoxy-codeine (1:1) successfully determined the concentrations of these individual components using such rate constant measurements. Consequently, variations in kinetics resulted in a significant difference between the relative chemiluminescence response based on peak area measurements and the relative response base on peak height measurements obtained using FIA. With regards to the observed reactivity of secondary amines and tertiary amines, chemiluminescence peak area determinations confirmed the vital role of pH on reaction efficiency, which was governed by structural features and kinetics. The tertiary amines investigated generally produced a greater emission under acidic conditions than the corresponding secondary amines. However, the measured chemiluminescence responses were highly dependent upon pH, with similar peak areas obtained for both amine groups under slightly alkaline conditions.

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We report on the impact of changes in the protic ionic liquid (pIL) cation on the fibrilisation kinetics and the conversion of the A 16-22 from monomers to amyloid fibrils. When we compare the use of primary, secondary, and tertiary amines we find that the primary amine results in the greatest conversion into amyloid fibrils. We show that the pIL is directly interacting with the peptide and this likely drives the difference in conversion and kinetics observed.

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We demonstrate a new approach to manipulate the selective emission in mixed electrogenerated chemiluminescence (ECL) systems, where subtle changes in co-reactant properties are exploited to control the relative electron-transfer processes of excitation and quenching. Two closely related tertiary-amine co-reactants, tri-n-propylamine and N,N-diisopropylethylamine, generate remarkably different emission profiles: one provides distinct green and red ECL from [Ir(ppy)3] (ppy=2-phenylpyridinato-C2,N) and a [Ru(bpy)3](2+) (bpy=2,2'-bipyridine) derivative at different applied potentials, whereas the other generates both emissions simultaneously across a wide potential range. These phenomena can be rationalized through the relative exergonicities of electron-transfer quenching of the excited states, in conjunction with the change in concentration of the quenchers over the applied potential range.

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A series of aliphatic tertiary amines (HEPES, POPSO, EPPS and BIS-TRIS) commonly used to buffer the pH in biological experiments, were examined as alternative, non-toxic co-reactants for the electrogenerated chemiluminescence (ECL) of tris(2,2'-bipyridine)ruthenium(ii) ([Ru(bpy)3](2+)). These were found to be very attractive as "multi-tasking" reagents, serving not only as co-reactants, but also fulfiling the roles of pH buffer and supporting electrolyte within an aqueous environment; thus significantly simplifying the overall ECL analysis. Sub-nanomolar detection limits were obtained for [Ru(bpy)3](2+) in the presence of BIS-TRIS, making this species an valuable option for co-reactant ECL-based bioanalytical applications.

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Tertiary study in journalism has been a feature of the education of Australian journalists for decades. Yet the value of what is loosely termed a “journalism degree” continues to be debated, and many industry representatives remain sceptical of its value. Journalism educators have a number of ways of assessing the level of industry acceptance of journalism education. These include looking at the percentage of students who find employment and the percentage of journalism graduates who fill entry level positions. This paper addresses the latter category, looking at data on the employment of entry-level journalists at four major institutions over a period of several years.

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Educational researchers have long derided the university lecture as an effective mode of delivery of educational materials, but currently there are many reports on the advantages offered by computer. In this study a multimedia solution was sought to replace existing face to face lectures because it appeared to offer a close 'media versus need' match. Consequently, a decision was made to develop a design template for an interactive computer based program that would be suitable for a range of subject content. In order to personalise the instruction, a large video insert was incorporated as the main screen's most prominent design feature. From here the learner could navigate to support material including interactive simulations. The program was piloted with a small group of students and, in particular, the student tracking data that the program automatically generates yield some interesting learning style information.

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A new family of Cheilostomata, the Calescharidae, is introduced for the genus Caleschara MacGillivray and its Recent Australian typespecies, C. denticulata(MacGillivray), which is redefined from type and other material. The Australian Tertiary genus Tretosina Canu & Bassler and its type species,T. arcifera Canu & Bassler, are closely related,and are also assigned to the Calescharidae. The history and significance of family attributions of both genera are outlined, and RecentC. denticulata from Australian and other localities is distinguished from the Late Tertiary Victorian species C. parva Maplestone. Caleschara lithconis, sp. nov., from the Late Eocene of Victoria is one of the earliest known species: its morphology closely resembles a Recent form from the Philippines, C. junctifera Canu & Bassler. Another Recent species, Caleschara minuta (Maplestone) from the GilbertIslands, is a senior synonym of three other Indo-Pacific species,C. levinseni Harmer, C. laxa Canu & Bassler and Floridinella arculifera Canu & Bassler, and resembles the European Paleocene C. squamosa. Three other related species are briefly discussed. Close relationships to other families are problematic and are discussed; divergence in the early history of the cheilostomes is inferred.

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The subgenus Anaskopora Wass, 1975 is raised to generic rank, separated from the genus Corbulipora, and redefined. The type species, Cribrilina elevata MacGillivray, 1895, is a Tertiary fossil from Victoria with small globular colonies formed principally by a special kind of interzooidal frontal budding. Other Tertiary fossil species with a similar colony structure, here assigned to Anaskopora, are Cribrilma cornuta MacGIllIvray, 1895 and Lepralia rotundata MacGillivray, 1895. Two further new Tertiary species, A. simplex and A. mesa, from Victoria and South Australia have small encrusting colonies. A key to species is given.

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The introduction of an online supported, resource based learning environment into a large, multi-modal first year psychology unit led to the spontaneous development of a small, but active, learning community. While off campus students were more active online contributors, many other students "observed" these interactions, not actively contributing but finding the discussion postings valuable to their learning. Overall, use and perceived value of the online communication facilities were related to how confident students were that they had an appropriate study strategy, with off campus and older students reporting greater confidence in their study approach. The results highlight that the nature and function of learning communities for large, multi-modal foundation units are quite different to those typically articulated in the literature and are worth further investigation.

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This paper discusses the higher education sector’s role in knowledge-based economy though research training, that is, doctoral education. It also examines how a Faculty of Education supports its doctoral candidates in their endeavours to become ‘knowledge producers’. Two themes are explored: one is Australia’s limited investment in education by international standards; and the other is the research training needs and circumstances of doctoral candidates who are located in professional and workplace contexts. The paper discusses the role of online support and a Doctoral Studies in Education (DSE) online seminar program to support primarily off-campus, part-time mid-career professionals. These are typical of many of Australia’s doctoral candidates. E-learning is examined as part of a comprehensive support and research training strategy for doctoral candidates studying at a distance. We discuss the sorts of opportunities and experiences our candidates receive and the extent to which they are readied to work effectively in a knowledge-based economy.

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After the jubilation of the first democratic election in 1994, South African educational settings were faced with the challenge to rethink curriculum, content and delivery as part of its nation building process. Education continues to be a major player in stimulating wider change in society and is one arena where change may be readily facilitated. Changing the style and practice of teacher education programs remains a key feature in the transformation process. Twelve years on, curriculum, has undergone reform in terms of Outcomes Based Education (OBE)? Revised National Curriculum Statement (RNCS) of 2002, accordingly, universities continue to prepare teachers for multicultural classrooms. Universities are now challenged to manage increased student intake (quantity) for teacher education programs without having to sacrifice quality for teacher education. This article focuses only on The University of Pretoria, a city university previously known as a traditional Afrikaans university situated in the greater Johannesburg area in South Africa. Through interview data with two music educators at this university, I present some of the current trends and challenges that tertiary music educators face in preparing music teachers in South Africa. This article also outlines a paradigm shift in the curriculum and argues for a holistic music education, one that endorses most of the major cultures and musics in South Africa. The question I pose is how then do we effectively manage change at tertiary level without sacrificing quality when preparing future music teachers to meet the needs and challenges of the curriculum and society.

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This paper is about challenges to the hegemony of printed books in Australian tertiary education and the potential demise of that hegemony. Not because the book in its traditional form is considered by some to be outdated and not because ofcompeting products that might put the use of the traditional book under threat - our Australian 'book-industry' might well rise to such challenges given that competitiveness is a driving feature of business. This paper is about challenges to the hegemony of printed books in tertiary education because of forces entirely outside the 'book-industry's' control.

The function of traditional printed books within tertiary education is changing. Education is a user-pays product, and competitive pressures ensure students are given greater voice in the types of learning resources provided, with the evolution of electronic and communication technologies allowing student learning resources to be made available in a myriad of ways. Thus a traditional printed book may be an inflexible tool in a dynamic environment.

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This paper is the result of a "Rip Van Winkle" experience I had concerning the teaching of Business Communication. The paper focuses on the remarkable expansion in the curriculum of the traditional "Business Communication" or "Business Writing" course offered by many tertiary institutions around the world. Based on 25 years of personal observation and experience in a number of educational settings, the paper will trace the increasing sophistication and complexity of the study of business communication from one that covered little more than lessons in the design of hardcopy memos, letters, and reports to one that now covers a broad spectrum of topics such as "emotional intelligence," "intercultural communication," "effective public speaking," as well as the effects of purpose and audience on the design of a wide variety of business communications.

An example of an effective task that involves a number of on the job activities is provided in the form of a ready to use assignment that is applicable in a number of contexts.