349 resultados para REFLECTANCE-DIFFERENCE SPECTROSCOPY


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The application of different EMS current thresholds on muscle activates not only the muscle but also peripheral sensory axons that send proprioceptive and pain signals to the cerebral cortex. A 32-channel time-domain fNIRS instrument was employed to map regional cortical activities under varied EMS current intensities applied on the right wrist extensor muscle. Eight healthy volunteers underwent four EMS at different current thresholds based on their individual maximal tolerated intensity (MTI), i.e., 10 % < 50 % < 100 % < over 100 % MTI. Time courses of the absolute oxygenated and deoxygenated hemoglobin concentrations primarily over the bilateral sensorimotor cortical (SMC) regions were extrapolated, and cortical activation maps were determined by general linear model using the NIRS-SPM software. The stimulation-induced wrist extension paradigm significantly increased activation of the contralateral SMC region according to the EMS intensities, while the ipsilateral SMC region showed no significant changes. This could be due in part to a nociceptive response to the higher EMS current intensities and result also from increased sensorimotor integration in these cortical regions.

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We have developed an explanation for ultra trace detection found when using Au/Ag SERS nanoparticles linked to biochemical affinity tags, e.g. antibodies. The nanoparticle structure is not as usually assumed and the aggregated nanoparticles constitute hot spots that are indispensable for these very low levels of analyte detection, even more so when using a direct detection method.

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The mineral olshanskyite is one of many calcium borate minerals which has never been studied using vibrational spectroscopy. The mineral is unstable and decomposes upon exposure to an electron beam. This makes the elemental analysis using EDX techniques difficult. Both the Raman and infrared spectra show complexity due to the complexity of the structure. Intense Raman bands are found at 989, 1,003, 1,025 and 1,069 cm-1 with a shoulder at 961 cm-1 and are assigned to trigonal borate units. The Raman bands at 1,141, 1,206 and 1,365 cm-1 are assigned to OH in-plane bending of BOH units. A series of Raman bands are observed in the 2,900–3,621cm-1 spectral range and are assigned to the stretching vibrations of OH and water. This complexity is also reflected in the infrared spectra. Vibrational spectroscopy enables aspects of the structure of olshanskyite to be elucidated.

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FTIR spectra are reported of methanol adsorbed at 295 K on ZnO/SiO 2, on reduced Cu/ZnO/SiO2 and on Cu/ZnO/SiO2 which had been preoxidised by exposure to nitrous oxide. Methanol on ZnO/SiO2 gave methoxy species on ZnO and SiO, in addition to both strongly and weakly physisorbed methanol on SiO2. The corresponding adsorption of methanol on reduced Cu/ZnO/SiO2 also gave methoxy species on Cu and a small amount of bridging formate. Reaction of methanol with a reoxidised Cu/ZnO/SiO2 catalyst resulted in an enhanced quantity of methoxy species on Cu. Heating adsorbed species on Cu/ZnO/SiO2 at 393 K led to the loss of methoxy groups on Cu and the concomitant formation of formate species on both ZnO and Cu. The comparable reaction on a reoxidised Cu/ZnO/SiO2 catalyst gave an increased amount of formate species on ZnO and this correlated with an increased quantity of methoxy groups lost from Cu. An explanation is given in terms of adsorption of formate and formaldehyde species at special sites located at the copper/zinc oxide interface.

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The reaction of CO2 and H2 with ZnO/SiO2 catalyst at 295 K gave predominantly hydrogencarbonate on zinc oxide and a small quantity of formate was evolved after heating at 393 K. Elevation of the reaction temperature to 503 K enhanced the rate of formation of zinc formate species. Significantly these formate species decomposed at 573 K almost entirely to CO2 and H2. Even after exposure of CO2-H2 or CO-CO2-H2 mixtures to highly defected ZnO/SiO2 catalyst, the formate species produced still decomposed to give CO2 and H2. It was concluded that carboxylate species which were formed at oxygen anion vacancies on polar Zn planes were not significantly hydrogenated to formate. Consequently it was proposed that the non-polar planes on zinc oxide contained sites which were specific for the synthesis of methanol. The interaction of CO2 and H2 with reduced Cu/ZnO/SiO2 catalyst at 393 K gave copper formate species in addition to substantial quantities of formate created at interfacial sites between copper and zinc oxide. It was deduced that interfacial formate species were produced from the hydrogenation of interfacial bidentate carbonate structures. The relevance of interfacial formate species in the methanol synthesis reaction is discussed. Experiments concerning the reaction of CO2-H2 with physical mixtures of Cu/SiO2 and ZnO/SiO2 gave results which were simply characteristic of the individual components. By careful consideration of previous data a detailed proposal regarding the role of spillover hydrogen is outlined. Admission of CO to a gaseous CO2-H2 feedstock resulted in a considerably diminished amount of formate species on copper. This was ascribed to a combination of over-reduction of the surface and site-blockage.

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The reactions of pyrrole and thiophene monomers in copper-exchanged mordenite have been investigated using EPR and UV–VIS absorption spectroscopy. The EPR spectra show a decrease in the intensity of the Cu2+ signal and the appearance of a radical signal due to the formation of oxidatively coupled oligomeric and/or polymeric species in the zeolite host. The reaction ceases when ca. 50% of the copper has reacted and differences in the form of the residual Cu2+ signal between the thiophene and pyrrole reactions suggest a greater degree of penetration of the reaction into the zeolite host for pyrrole, in agreement with previous XPS measurements. The EPR signal intensities show that the average length of the polymer chain that is associated with each radical centre is 15–20 and 5–7 monomer units for polypyrrole and polythiophene, respectively. The widths of the EPR signals suggest that these are at least partly due to small oligomers. The UV–VIS absorption spectra of the thiophene system show bands in three main regions: 2.8–3.0 eV (A), 2.3 eV (B) and 1.6–1.9 eV (D, E, F). Bands A and D–F occur in regions which have previously been observed for small oligomers, 4–6 monomer units in length. Band B is assigned to longer chain polythiophene molecules. We therefore conclude that the reaction between thiophene and copper-loaded mordenite produces a mixture of short oligomers together with some long chain polythiophene. The UV–VIS spectra of the pyrrole system show bands in the regions 3.6 eV (A), 2.7–3.0 eV (B, C) and 1.5–1.9 eV (D, F). Assignments of these bands are less certain than for the thiophene case because of the lack of literature data on the spectra of pyrrole oligomers.

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There is a large number of boron containing minerals with water and/or hydroxyl units of which pinnoite MgB2O(OH)6 is one. Some discussion about the molecular structure of pinnoite exists in the literature. Whether water is involved in the structure is ill-determined. The molecular structure of pinnoite has been assessed by the combination of Raman and infrared spectroscopy. The Raman spectrum is characterized by an intense band at 900 cm−1 assigned to the BO stretching vibrational mode. A series of bands in the 1000–1320 cm−1 spectral range are attributed to BO antisymmetric stretching modes and in-plane bending modes. The infrared spectrum shows complexity in this spectral range. Multiple Raman OH stretching vibrations are found at 3179, 3399, 3554 and 3579 cm−1. The infrared spectrum shows a series of overlapping bands with bands identified at 3123, 3202, 3299, 3414, 3513 and 3594 cm−1. By using a Libowitzky type function, hydrogen bond distances were calculated. Two types of hydrogen bonds were identified based upon the hydrogen bond distance. It is important to understand the structure of pinnoite in order to form nanomaterials based upon the pinnoite structure.

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Drawing on critical social theory and transformative learning, this study investigates the sociocultural factors that enable a move away from the deficit model of learning. The multicase study examines beginning teachers’ perceptions of learning and teaching for students experiencing learning difficulties. The fluid conception of identity occupied by beginning teachers was explored as the participants challenged structural ideologies and their personal belief systems. The study argues that personal factors such as, engaging in critical reflection and beliefs, and school factors such as job security and school context influence how beginning teachers respond to diverse learners and position themselves as agentive.

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Grading osteoarthritic tissue has, until now, been a laboratory process confined to research activities. This thesis establishes a scientific protocol that extends osteoarthritic tissue ranking to surgical practice. The innovative protocol, which now incorporates the structural degeneration of collagen, enhances the traditional Modified Mankin ranking system, enabling its application to real time decision during surgery. Because it is fast and without time consuming laboratory process, it would potentially enable the cataloguing of tissues in osteoarthritic joints in all compartments of diseased joints during surgery for epistemological study and insight into the manifestation of osteoarthritis across age, gender, occupation, physical activities and race.

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Anthropomorphism is a cognitive bias, which occurs when individuals see human characteristics in a non-human agent, object or animal. Anthropomorphism is especially interesting to marketers, because once anthropomorphic bias has been triggered, it can lead to a greater feeling of connectedness to a non-human agent (Tam, Lee and Chao, 2013), the emulation of behaviours (Aggarwal and McGill, 2012) or greater attribution of brand personality and brand liking (Delbaere, McQuarrie and Phillips, 2011). Importantly, research now shows that levels of this tendency vary between individuals (Waytz, Cacioppo and Epley, 2010), but research to date has failed to focus on how anthropomorphic tendency influences individual responses to marketing communications messages. Spokes-characters present an ideal context through which to examine this gap, given that they function as personified brands, designed to trigger consumer anthropomorphic tendency. Further, little is understood about how spokes-characters operate and which consumers will prefer them to their human counterparts. Like anthropomorphic research, much empirical work to date has focused on design and outcomes, examining the sender’s encoding process and the feedback generated, but ignoring the individual decoding process that is so important to understanding individual differences and message effectiveness. The current research employs three experiments using an online survey with stimulus exposure to show that anthropomorphic tendency, personality similarity and spokes-character type all have relevance to the understanding of this complex relationship. Study one and two indicate that while a human spokesperson is still preferred by many, higher levels of anthropomorphic tendency increase likeability of cartoon spokes characters. Study three highlights the importance of personality similarity, which further increases likability. Additional analyses provide key findings concerning the nature of anthropomorphic tendency as an individual difference and trait. This research contributes to a greater understanding of anthropomorphism theory and fills existing gaps in the consumer psychology and marketing communications literature.

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Decision makers frequently use separate participatory activities to involve marginalised groups. This approach can generate valuable insights, but it has limitations. We discuss the benefits and limits through two examples involving young people, and outline how the approach can be modified, thereby building citizens who are responsive to other perspectives.

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The determination of the characteristics of articular cartilage such as thickness, stiffness and swelling, especially in the form that can facilitate real-time decisions and diagnostics is still a matter for research and development. This paper correlates near infrared spectroscopy with mechanically measured cartilage thickness to establish a fast, non-destructive, repeatable and precise protocol for determining this tissue property. Statistical correlation was conducted between the thickness of bovine cartilage specimens (n = 97) and regions of their near infrared spectra. Nine regions were established along the full absorption spectrum of each sample and were correlated with the thickness using partial least squares (PLS) regression multivariate analysis. The coefficient of determination (R2) varied between 53 and 93%, with the most predictive region (R2 = 93.1%, p < 0.0001) for cartilage thickness lying in the region (wavenumber) 5350–8850 cm−1. Our results demonstrate that the thickness of articular cartilage can be measured spectroscopically using NIR light. This protocol is potentially beneficial to clinical practice and surgical procedures in the treatment of joint disease such as osteoarthritis.

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This thesis investigates the use of near infrared (NIR) spectroscopic methods for rapid measurement of nutrient elements in mill mud and mill ash. Adoption of NIR-based analyses for carbon, nitrogen, phosphorus, potassium and silicon will allow Australian sugarcane farmers to comply with recent legislative changes, and act within recommended precision farming frameworks. For these analyses, NIR spectroscopic methods surpass several facets of traditional wet chemistry techniques, dramatically reducing costs, required expertise and chemical exposure, while increasing throughput and access to data. Further, this technology can be applied in various modes, including laboratory, at-line and on-line installations, allowing targeted measurement.

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In this paper, we have investigated on the natural wendwilsonite mineral with the formulae Ca2(Mg,Co)(AsO4)2⋅2(H2O). Raman spectroscopy complimented with infrared spectroscopy has been used to determine the molecular structure of the wendwilsonite arsenate mineral. A comparison is made with the roselite mineral group with formula Ca2B(AsO4)2⋅2H2O (where B may be Co, Fe2+, Mg, Mn, Ni, Zn). The Raman spectra of the arsenate related to tetrahedral arsenate clusters with stretching region shows strong differences between that of wendwilsonite and the roselite arsenate minerals which is attributed to the cation substitution for calcium in the structure. The Raman arsenate (AsO4)3− stretching region shows strong differences between that of wendwilsonite and the roselite arsenate minerals which is attributed to the cation substitution for calcium in the structure. In the infrared spectra complexity exists of multiple to tetrahedral (AsO4)3− clusters with antisymmetric stretching vibrations observed indicating a reduction of the tetrahedral symmetry. This loss of degeneracy is also reflected in the bending modes. Strong Raman bands around 450 cm−1 are assigned to ν4 bending modes. Multiple bands in the 350–300 cm−1 region assigned to ν2 bending modes provide evidence of symmetry reduction of the arsenate anion. Three broad bands for wendwilsonite found at 3332, 3119 and 3001 cm−1 are assigned to OH stretching bands. By using a Libowitzky empirical equation, hydrogen bond distances of 2.65 and 2.75 Å are estimated. Vibrational spectra enable the molecular structure of the wendwilsonite mineral to be determined and whilst similarities exist in the spectral patterns with the roselite mineral group, sufficient differences exist to be able to determine the identification of the minerals.

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Raman spectroscopy was used to characterize and differentiate the two minerals calcite and dolomite and the bands related to the mineral structure. The (CO3)2− group is characterized by four prominent Raman vibrational modes: (a) the symmetric stretching, (b) the asymmetric deformation, (c) asymmetric stretching and (d) symmetric deformation. These vibrational modes of the calcite and dolomite were observed at 1440, 1088, 715 and 278 cm−1. The significant differences between the minerals calcite and dolomite are observed by Raman spectroscopy. Calcite shows the typical bands observed at 1361, 1047, 715 and 157 cm−1, and the special bands at 1393, 1098, 1069, 1019, 299, 258 and 176 cm−1 for dolomite are observed. The difference is explained on the basis of the structure variation of the two minerals. Calcite has a trigonal structure with two molecules per unit cell, and dolomite has a hexagonal structure. This is more likely to cause the splitting and distorting of the carbonate groups. Another cause for the difference is the cation substituting for Mg in the dolomite mineral.