A raman and infrared spectroscopic study of Ca2+ dominant members of the mixite group from the Czech Republic

Raman microscopy of two mixite minerals BiCu6(AsO4)3(OH)6.3H2O from Jáchymov and from Smrkovec (both Czech Republic) has been used to study their molecular structure, which is interpreted and the presence of (AsO4)3-, (AsO3OH)2-, (PO4)3- and (PO3OH)2- units, molecular water and hydroxyl ions were inferred. O-H…O hydrogen bond lengths were calculated from the Raman and infrared spectra using Libowitzky’s empirical relation. Small differences in the Raman spectra between both samples were observed and attributed to compositional and hydrogen bonding network differences.

A Raman spectroscopic study of copiapites Fe2+Fe3+(SO4)6(OH)2 · 20H2O: environmental implications

Raman spectroscopy has been used to study selected mineral samples of the copiapite group. Copiapite (Fe2+Fe3+(SO4)6(OH)2 · 20H2O) is a secondary mineral formed through the oxidn. of pyrite. Minerals of the copiapite group have the general formula AFe4(SO4)6(OH)2 · 20H2O, where A has a + 2 charge and can be either magnesium, iron, copper, calcium and/or zinc. The formula can also be B2/3Fe4(SO4)6(OH)2 · 20H2O, where B has a + 3 charge and may be either aluminum or iron. For each mineral, two Raman bands are obsd. at around 992 and 1029 cm-1, assigned to the (SO4)2-ν1 sym. stretching mode. The observation of two bands provides evidence for the existence of two non-equiv. sulfate anions in the mineral structure. Three Raman bands at 1112, 1142 and 1161 cm-1 are obsd. in the Raman spectrum of copiapites, indicating a redn. of symmetry of the sulfate anion in the copiapite structure. This redn. in symmetry is supported by multiple bands in the ν2 and ν4(SO4)2- spectral regions.

Raman spectroscopic study of the uranyl titanate mineral euxenite (Y,Ca,U,Ce,Th) (Nb,Ta,Ti)2O6

Raman spectra of the uranyl titanate mineral euxenite were analyzed and related to the mineral structure. A comparison is made with the Raman spectra of uranyl oxyhydroxide hydrates. The obsd. bands are attributed to the Ti[n.63743]O and (UO2)2+ stretching and bending vibrations, as well as lattice vibrations of rare-earth ions. The Raman bands of euxenite are in harmony with those of the uranyl oxyhydroxides. The mineral euxenite is metamict as is evidenced by the intensity of the U[n.63743]O stretching and bending modes, which are of lower intensity than expected, and with bands that are significantly broader.

Probabilistic subgroup identification using Bayesian finite mixture modelling : a case study in Parkinson’s disease phenotype identification

This article explores the use of probabilistic classification, namely finite mixture modelling, for identification of complex disease phenotypes, given cross-sectional data. In particular, if focuses on posterior probabilities of subgroup membership, a standard output of finite mixture modelling, and how the quantification of uncertainty in these probabilities can lead to more detailed analyses. Using a Bayesian approach, we describe two practical uses of this uncertainty: (i) as a means of describing a person’s membership to a single or multiple latent subgroups and (ii) as a means of describing identified subgroups by patient-centred covariates not included in model estimation. These proposed uses are demonstrated on a case study in Parkinson’s disease (PD), where latent subgroups are identified using multiple symptoms from the Unified Parkinson’s Disease Rating Scale (UPDRS).

A study of laughter in science lessons

Laughter is a fundamental human phenomenon. Yet there is little educational research on the potential functions of laughter on the enacted (lived) curriculum. In this study, we identify the functions of laughter in a beginning science teacher’s classroom throughout her first year of teaching. Our study shows that laughter is more than a gratuitous phenomenon. It is the result of a collective interactive achievement of the classroom participants that offsets the seriousness of science as a discipline. Laughter, whereas it challenges the seriousness of science, also includes the dialectical inversion of the challenge: it simultaneously reinforces the idea of science as serious business.

Experimental study of the concentration field of discharge from a boat propeller

Two-stroke outboard boat engines using total loss lubrication deposit a significant proportion of their lubricant and fuel directly into the water. The purpose of this work is to document the velocity and concentration field characteristics of a submerged swirling water jet emanating from a propeller in order to provide information on its fundamental characteristics. The properties of the jet were examined far enough downstream to be relevant to the eventual modelling of the mixing problem. Measurements of the velocity and concentration field were performed in a turbulent jet generated by a model boat propeller (0.02 m diameter) operating at 1500 rpm and 3000 rpm in a weak co-flow of 0.04 m/s. The measurements were carried out in the Zone of Established Flow up to 50 propeller diameters downstream of the propeller, which was placed in a glass-walled flume 0.4 m wide with a free surface depth of 0.15 m. The jet and scalar plume development were compared to that of a classical free round jet. Further, results pertaining to radial distribution, self similarity, standard deviation growth, maximum value decay and integral fluxes of velocity and concentration were presented and fitted with empirical correlations. Furthermore, propeller induced mixing and pollutant source concentration from a two-stroke engine were estimated.

Vibrational spectroscopic study of the antimonate mineral bindheimite Pb2Sb2O6(O,OH)

Raman spectroscopy complimented with infrared spectroscopy has been used to characterise the antimonate mineral bindheimite Pb2Sb2O6(O,OH). The mineral is characterised by an intense Raman band at 656 cm-1 assigned to SbO stretching vibrations. Other lower intensity bands at 664, 749 and 814 cm-1 are also assigned to stretching vibrations. This observation suggests the non-equivalence of SbO units in the structure. Low intensity Raman bands at 293, 312 and 328 cm-1 are assigned to the OSbO bending vibrations. Infrared bands at 979, 1008, 1037 and 1058 cm-1 may be assigned to δ OH deformation modes of SbOH units. Infrared bands at 1603 and 1640 cm-1 are assigned to water bending vibrations, suggesting that water is involved in the bindheimite structure. Broad infrared bands centred upon 3250 cm-1 supports this concept. Thus the true formula of bindheimite is questioned and probably should be written as Pb2Sb2O6(O,OH,H2O)

An infrared study of adsorption of paranitrophenol on mono, di and trialkyl surfactant intercalated organoclays

Infrared spectroscopy has been used to study the adsorption of paranitrophenol on mono, di and tri alkyl surfactant intercalated montmorillonite. Organoclays were obtained by the cationic exchange of mono, di and tri alkyl chain surfactants for sodium ions [hexadecyltrimethylammonium bromide (HDTMAB), dimethyldioctadecylammonium bromide (DDOAB), methyltrioctadecylammonium bromide (MTOAB)] in an aqueous solution with Na-montmorillonite. Upon formation of the organoclay, the properties change from strongly hydrophilic to strongly hydrophobic. This change in surface properties is observed by a decrease in intensity of the OH stretching vibrations assigned to water in the cation hydration sphere of the montmorillonite. As the cation is replaced by the surfactant molecules the paranitrophenol replaces the surfactant molecules in the clay interlayer. Bands attributed to CH stretching and bending vibrations change for the surfactant intercalated montmorillonite. Strong changes occur in the HCH deformation modes of the methyl groups of the surfactant. These changes are attributed to the methyl groups locking into the siloxane surface of the montmorillonite. Such a concept is supported by changes in the SiO stretching bands of the montmorillonite siloxane surface. This study demonstrates that paranitrophenol will penetrate into the untreated clay interlayer and replace the intercalated surfactant in surfactant modified clay, resulting in the change of the arrangement of the intercalated surfactant.

Thermal decomposition of hydrotalcite with hexacyanoferrite(II) and hexacyanoferrate(III) anions in the interlayer : a controlled rate thermal analysis study

The mechanism for the decomposition of hydrotalcite remains unsolved. Controlled rate thermal analysis enables this decomposition pathway to be explored. The thermal decomposition of hydrotalcites with hexacyanoferrite(II) and hexacyanoferrate(III) in the interlayer has been studied using controlled rate thermal analysis technology. X-ray diffraction shows the hydrotalcites studied have a d(003) spacing of 11.1 and 10.9 Å which compares with a d-spacing of 7.9 and 7.98 Å for the hydrotalcite with carbonate or sulphate in the interlayer. Calculations based upon CRTA measurements show that 7 moles of water is lost, proving the formula of hexacyanoferrite(II) intercalated hydrotalcite is Mg6Al2(OH)16[Fe(CN)6]0.5 .7 H2O and for the hexacyanoferrate(III) intercalated hydrotalcite is Mg6Al2(OH)16[Fe(CN)6]0.66 * 9 H2O. Dehydroxylation combined with CN unit loss occurs in three steps between a) 310 and 367°C b) 367 and 390°C and c) between 390 and 428°C for both the hexacyanoferrite(II) and hexacyanoferrate(III) intercalated hydrotalcite.

'Which is the best Doctor Who story?' : a case study in value judgements outside the academy'

One of Cultural Studies' most important contributions to academic thinking about culture is the acceptance as axiomatic that we must not simply accept traditional value hierarchies in relation to cultural objects (see, for example, McGuigan, 1992: 157; Brunsdon, 1997: 5; Wark, 2001). Since Richard Hoggart and Raymond Williams took popular culture as a worthy object of study, Cultural Studies practitioners have accepted that the terms in which cultural debate had previously been conducted involved a category error. Opera is not 'better' than pop music, we believe in Cultural Studies - 'better for what?', we would ask. Similarly, Shakespeare is not 'better' than Mills and Boon, unless you can specify the purpose for which you want to use the texts. Shakespeare is indeed better than Mills and Boon for understanding seventeenth century ideas about social organisation; but Mills and Boon is unquestionably better than Shakespeare if you want slightly scandalous, but ultimately reassuring representations of sexual intercourse. The reason that we do not accept traditional hierarchies of cultural value is that we know that the culture that is commonly understood to be 'best' also happens to be that which is preferred by the most educated and most materially well-off people in any given culture (Bourdieu, 1984: 1- 2; Ross, 1989: 211). We can interpret this information in at least two ways. On the one hand, it can be read as proving that the poorer and less well-educated members of a society do indeed have tastes which are innately less worthwhile than those of the material and educational elite. On the other hand, this information can be interpreted as demonstrating that the cultural and material elite publicly represent their own tastes as being the only correct ones. In Cultural Studies, we tend to favour the latter interpretation. We reject the idea that cultural objects have innate value, in terms of beauty, truth, excellence, simply 'there' in the object. That is, we reject 'aesthetic' approaches to culture (Bourdieu, 1984: 6; 485; Hartley, 1994: 6)1. In this, Cultural Studies is similar to other postmodern institutions, where high and popular culture can be mixed in ways unfamiliar to modernist culture (Sim, 1992: 1; Jameson, 1998: 100). So far, so familiar.

Structural inquiry, human agency and the contribution of Harre and Bhaskar : a case study of Wright’s “Classes”

This paper examines the contribution of aspects of critical and referential realism to the “logic” of structural explanation through an analysis of Erik Olin Wright’s Classes and the debate surrounding this work. Wright’s Classes has been selected as a case study because it offers an opportunity to examine issues pertaining to “objective” and “subjective” determinations of class and related questions of agency and structure at the level of actual methodological strategies. A close examination of the structure of Wright’s inquiry reveals a number of places where Harre’s and Bhaskar’s approaches may contribute to the prescription of methodological strategies which could overcome some of the antinomies on which the debate on Classes is based. As a case study, the paper underlines the important “underlabourer” role of critical and referential realism and their contribution to questions of agency and structure in the context of actual stages involved in structural explanation

A Raman spectroscopic study of the ‘cave’ mineral ardealite Ca2(HPO4)(SO4)•4H2O

The mineral ardealite Ca2(HPO4)(SO4)•4H2O is a ‘cave’ mineral and is formed through the reaction of calcite with bat guano. The mineral shows disorder and the composition varies depending on the origin of the mineral. Raman spectroscopy complimented with infrared spectroscopy has been used to characterise the mineral ardealite. The Raman spectrum is very different from that of gypsum. Bands are assigned to SO42- and HPO42- stretching and bending modes.

Characterisation of organoclays and adsorption of p-nitrophenol : environmental application

Organoclays were synthesised through ion exchange of a single surfactant for sodium ions, and characterised by a range of method including X-ray diffraction (XRD), BET, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). The change in surface properties of montmorillonite and organoclays intercalated with the surfactant, tetradecyltrimethylammonium bromide (TDTMA) were determined using XRD through the change in basal spacing and the expansion occurred by the adsorbed p-nitrophenol. The changes of interlayer spacing were observed in TEM. In addition, the surface measurement such as specific surface area and pore volume was measured and calculated using BET method, this suggested the loaded surfactant is highly important to determine the sorption mechanism onto organoclays. The collected results of XPS provided the chemical composition of montmorillonite and organoclays, and the high-resolution XPS spectra offered the chemical states of prepared organoclays with binding energy. Using TGA and FT-IR, the confirmation of intercalated surfactant was investigated. The collected data from various techniques enable an understanding of the changes in structure and surface properties. This study is of importance to provide mechanisms for the adsorption of organic molecules, especially in contaminated environmental sites and polluted waters.

Study of the interaction between 10-hydroxycamptothecine and DNA with the use of ethidium bromide dye as a fluorescence probe

The interaction of 10-hydroxycamptothecine (HCPT) with DNA under pseudo-physiological conditions (Tris-HCl buffer of pH 7.4), using ethidium bromide (EB) dye as a probe, was investigated with the use of spectrofluorimetry, UV-vis spectrometry and viscosity measurement. The binding constant and binding number for HCPT with DNA were evaluated as (7.1 ± 0.5) × 104 M-1 and 1.1, respectively, by multivariate curve resolution-alternating least squares (MCR-ALS). Moreover, parallel factor analysis (PARAFAC) was applied to resolve the three-way fluorescence data obtained from the interaction system, and the concentration information for the three components of the system at equilibrium was simultaneously obtained. It was found that there was a cooperative interaction between the HCPT-DNA complex and EB, which produced a ternary complex of HCPT-DNA-EB. © 2011 Elsevier B.V.

Indigenous Voice : a work-integrated learning case study in journalism education

The continuing stereotypical coverage of Inigenous affairs in the Australian media suggests that journalists are still finding it difficult to come to terms with more effective ways ofm reporting such issues. The many hundreds of students who graduate from journalism programs across Australia represent an opportunity to at least challenge the predominant methods and strategies. But how prepared are journalism graduates for working with Indigenous issues? This paper explores the processas involved in an intensive reporting practices course held at the University of Queensland mid-2009. The course aimed to raise journalism student's awareness of some of the issues involved as well as enabling them to interact and work with personnel from the Brisbane Indigenous Media Community, 98.9 fm, the National Indigenous Radio Service, SBS and the ABC. The findings suggest that such structured programs have a significant impact on changing student's perceptions of, and approaches to, their role and journalists.