107 resultados para minerals retention
em Queensland University of Technology - ePrints Archive
Resumo:
Raman spectra of chillagite, wulfenite, stolzite, scheelite and wolframite were obtained at 298 and 77 K using a Raman microprobe in combination with a thermal stage. Chillagite is a solid solution of wulfenite and stolzite. The spectra of these molybdate minerals are orientation dependent. The band at 695 cm-1 is interpreted as an antisymmetric bridging mode associated with the tungstate chain. The bands at 790 and 881 cm-1 are associated with the antisymmetric and symmetric Ag modes of terminal WO2 whereas the origin of the 806 cm-1 band remains unclear. The 4(Eg) band was absent for scheelite. The bands at 353 and 401 cm-1 are assigned as either deformation modes or as r(Bg) and (Ag) modes of terminal WO2. The band at 462 cm-1 has an equivalent band in the infrared at 455 cm-1 assigned as as(Au) of the (W2O4)n chain. The band at 508 cm-1 is assigned as sym(Bg) of the (W2O4)n chain.
Resumo:
A series of selected autunites with phosphate as the anion have been studied using infrared spectroscopy. Each autunite mineral has its own characteristic spectrum. The spectra for different autunites with the same composition are different. It is proposed that this difference is due to the structure of water and hydrated cations in the interlayer region between the uranyl phosphate sheets. This structure is different for different autunites. The position of the water hydroxyl stretching bands is related to the strength of the hydrogen bonds as determined by hydrogen bond distance. The highly ordered structure of water is also observed in the water HOH bending modes where a high wavenumber bands are observed. The phosphate and uranyl stretching vibrations overlap and are obtained by curve resolution.
Resumo:
A series of molybdate bearing minerals including wulfenite, powellite, lindgrenite and iriginite have been analysed by Raman microscopy. These minerals are closely related and often have related paragenesis. Raman microscopy enables the selection of individual crystals of these minerals for spectroscopic analysis even though several of the minerals can be found in the same matrix because of the paragenetic relationships between the minerals. The molybdenum bearing minerals lindgrenite, iriginite and koechlinite were studied by scanning electron microscopy and compositionally analysed by EDX methods using an electron probe before Raman spectroscopic analyses. The Raman spectra are assigned according to factor group analysis and related to the structure of the minerals. These minerals have characteristically different Raman spectra.
Resumo:
The application of Raman spectroscopy to the study of the copper chloride minerals nantokite, eriochalcite and claringbullite has enabled the vibrational modes for the CuCl, CuOH and CuOH2 to be determined. Nantokite is characterised by bands at 205 and 155 cm-1 attributed to the transverse and longitudinal optic vibrations. Nantokite also has an intense band at 463 cm-1, eriochalcite at 405 and 390 cm-1 and claringbullite at 511 cm-1. These bands are attributed to CuO stretching modes. Water librational bands at around 672 cm-1 for eriochalcite have been identified and hydroxyl deformation modes of claringbullite at 970, 906 and 815 cm-1 are observed. Spectra of the three minerals are so characteristically different that the minerals are readily identified by Raman spectroscopy. The minerals are often determined in copper corrosion products by X-ray diffraction. Raman spectroscopy offers a rapid, in-situ technique for the identification of these corrosion products.
Resumo:
Magnesium minerals are important in the understanding of the concept of geosequestration. The two hydrated hydroxy magnesium carbonate minerals artinite and dypingite have been studied by Raman spectroscopy. Intense bands are observed at 1092 cm-1 for artinite and at 1120 cm-1 for dypingite attributed CO32- ν1 symmetric stretching mode. The CO32- ν3 antisymmetric stretching vibrations are extremely weak and are observed at1412 and 1465 cm-1 for artinite and at 1366, 1447 and 1524 cm-1 for dypingite. Very weak Raman bands at 790 cm-1 for artinite and 800 cm-1 for dypingite are assigned to the CO32- ν2 out-of-plane bend. The Raman band at 700 cm-1 of artinite and at 725 and 760 cm-1 of dypingite are ascribed to CO32- ν2 in-plane bending mode. The Raman spectrum of artinite in the OH stretching region is characterised by two sets of bands: (a) an intense band at 3593 cm-1 assigned to the MgOH stretching vibrations and (b) the broad profile of overlapping bands at 3030 and 3229 cm-1 attributed to water stretching vibrations. X-ray diffraction studies show the minerals are disordered. This is reflected in the difficulty of obtaining Raman spectra of reasonable quality and explains why the Raman spectra of these minerals have not been previously or sufficiently described.
Resumo:
Relationship dissolution has been somewhat ignored in the study of relationship marketing paradigm. While there has been an abundance of literature giving broad conceptualizations on how to master the intricacies of relationships, very little has discussed the concept of relationship dissolution. This is especially true of the sporting industry, which does not yet understand the factors that contribute to members relinquishing their membership and severing relationship ties with the club. Team performance was found to be the most powerful predictor of relationship dissolution; however, both satisfaction with the sportscape and emotional bonds had a significant influence on the decision for a member not to renew their membership. Although team performance is mostly out of the hands of sport marketers, greater focus should be given to implementing strategies that enhance the emotional aspects of the club-member relationship while also improving aspects of the service facility.
Resumo:
Institutions should enact holistic approaches that address students’ personal, social and academic engagement in the early weeks of first year to facilitate retention (Nelson, Kift & Clarke, 2008). This holistic approach is central to the FYE program at Queensland University of Technology (QUT), which was established to maximise learning engagement and hence positively influence the retention of commencing students. The program aims to • engage students in their learning through an intentionally designed and enacted curriculum (Kift, 2008) • facilitate timely access to life and learning support • promote a sense of belonging to the discipline, cohort and profession. The FYE program’s aims are achieved by strategic alliances between academic and professional staff across the institution.
Resumo:
Institutions should enact holistic approaches that address students’ personal, social and academic engagement in the early weeks of first year to facilitate retention (Nelson, Kift & Clarke, 2008). This holistic approach is central to the FYE program at Queensland University of Technology (QUT), which was established to maximise learning engagement and hence positively influence the retention of commencing students.
Resumo:
It has been argued that intentional first year curriculum design has a critical role to play in enhancing first year student engagement, success and retention (Kift, 2008). A fundamental first year curriculum objective should be to assist students to make the successful transition to assessment in higher education. Scott (2006) has identified that ‘relevant, consistent and integrated assessment … [with] prompt and constructive feedback’ are particularly relevant to student retention generally; while Nicol (2007) suggests that ‘lack of clarity regarding expectations in the first year, low levels of teacher feedback and poor motivation’ are key issues in the first year. At the very minimum, if we expect first year students to become independent and self-managing learners, they need to be supported in their early development and acquisition of tertiary assessment literacies (Orrell, 2005). Critical to this attainment is the necessity to alleviate early anxieties around assessment information, instructions, guidance, and performance. This includes, for example: inducting students thoroughly into the academic languages and assessment genres they will encounter as the vehicles for evidencing learning success; and making expectations about the quality of this evidence clear. Most importantly, students should receive regular formative feedback of their work early in their program of study to aid their learning and to provide information to both students and teachers on progress and achievement. Leveraging research conducted under an ALTC Senior Fellowship that has sought to articulate a research-based 'transition pedagogy' (Kift & Nelson, 2005) – a guiding philosophy for intentional first year curriculum design and support that carefully scaffolds and mediates the first year learning experience for contemporary heterogeneous cohorts – this paper will discuss theoretical and practical strategies and examples that should be of assistance in implementing good assessment and feedback practices across a range of disciplines in the first year.
Resumo:
Sandy soils have low water and nutrient retention capabilities so that zeolite soil amendments are used for high value land uses including turf and horticulture to reduce leaching losses of NH4+ fertilisers. MesoLite is a zeolitic material made by caustic treatment of kaolin at 80-95oC. It has a moderately low surface area (9-12m2/g) and very high cation exchange capacity (494 cmol(+)/kg). Laboratory column experiments showed that an addition of 0.4% MesoLite to a sandy soil greatly (90%) reduced leaching of added NH4+ compared to an unamended soil and MesoLite is 11 times more efficient in retaining NH4+ than natural zeolite. Furthermore, NH4+-MesoLite slowly releases NH4+ to soil solution and is likely to be an effective slow release fertiliser.
Resumo:
Batch, column and field lysimeter studies have been conducted to evaluate the concept of codisposal of retort water with Rundle (Queensland, Australia) waste shales. The batch studies indicated that degradation of a significant proportion of the total organic load occurs if the mixture is seeded with soil or compost. These results are compared with those from laboratory column studies and from the field lysimeter at the Rundle site. G.c.-m.s. analysis of some of the eluants indicated that significant degradation of the base-neutral fraction occurs even if no soil seed is added, and that degradation of this fraction was higher under anaerobic conditions.