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Raman Microscopy (raman + microscopy)
Kinds of Raman Microscopy Selected AbstractsConfocal Raman Microscopy as a Tool to Investigate Concentration Profiles of Melt Crystallized Ibuprofen/Carnauba WaxCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2009H. Qu Abstract Coatings are of great significance for pharmaceutical solid dosage forms. They fulfil a number of functions and are often necessary to control drug delivery, to mask bitter taste, or to protect the active pharmaceutical ingredient from detrimental environmental factors. The process of self-coating by melt crystallization of a suitable binary mixture eliminates the need for an additional process step in the manufacture of a solid drug. Self-coating relies upon the physical and spatial separation of individual components in a melt during solidification. This paper focuses on the use of confocal Raman microscopy as a nondestructive technique for quantifying the spatial distribution of the components in self-coated pastilles manufactured from the binary system ibuprofen/carnauba wax. Pastilles are produced from the melt. Raman spectroscopy allows the direct analysis of concentration profiles across the surface of the pastille. Here, the samples are cleaved and the cleaved surface is investigated in order to establish the distribution of the components in the interior of the solid. A univariate calibration model was developed and statistically validated with standard mixtures of ibuprofen and carnauba wax. Different regression models (linear or polynomial, using different significant peaks for the respective compounds) were assessed and a linear model was found to be adequate to determine the concentration gradient in the pastilles. [source] Raman-FISH: combining stable-isotope Raman spectroscopy and fluorescence in situ hybridization for the single cell analysis of identity and functionENVIRONMENTAL MICROBIOLOGY, Issue 8 2007Wei E. Huang Summary We have coupled fluorescence in situ hybridization (FISH) with Raman microscopy for simultaneous cultivation-independent identification and determination of 13C incorporation into microbial cells. Highly resolved Raman confocal spectra were generated for individual cells which were grown in minimal medium where the ratio of 13C to 12C content of the sole carbon source was incrementally varied. Cells which were 13C-labelled through anabolic incorporation of the isotope exhibited key red-shifted spectral peaks, the calculated ,red shift ratio' (RSR) being highly correlated with the 13C-content of the cells. Subsequently, Raman instrumentation and FISH protocols were optimized to allow combined epifluorescence and Raman imaging of Fluos, Cy3 and Cy5-labelled microbial populations at the single cell level. Cellular 13C-content determinations exhibited good congruence between fresh cells and FISH hybridized cells indicating that spectral peaks, including phenylalanine resonance, which were used to determine 13C-labelling, were preserved during fixation and hybridization. In order to demonstrate the suitability of this technology for structure,function analyses in complex microbial communities, Raman-FISH was deployed to show the importance of Pseudomonas populations during naphthalene degradation in groundwater microcosms. Raman-FISH extends and complements current technologies such as FISH-microautoradiography and stable isotope probing in that it can be applied at the resolution of single cells in complex communities, is quantitative if suitable calibrations are performed, can be used with stable isotopes and has analysis times of typically 1 min per cell. [source] The effect of ageing on the elastic modulus and degree of conversion of two multistep adhesive systemsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2010Giulio Marchesi Marchesi G, Navarra CO, Cadenaro M, Carrilho MR, Codan B, Sergo V, Di Lenarda R, Breschi L. The effect of ageing on the elastic modulus and degree of conversion of two multistep adhesive systems. Eur J Oral Sci 2010; 118: 304,310. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci During the curing reaction, the monomers of dentine bonding systems should cross-link sufficiently to strengthen an adhesive so that it is clinically reliable. This study evaluated how different storage conditions (air vs. water storage) affect the elastic modulus (E-modulus) and degree of conversion (DC) of a three-step etch-and-rinse adhesive and a two-step self-etch adhesive. The biaxial flexural test and Raman microscopy were performed on resin disks made from the bonding agents Adper Scotchbond Multi-Purpose (SBMP; 3M ESPE) and Clearfil Protect Bond (CPB; Kuraray). The measurements were repeated after storage in either air or water for 15 and 30 min and for 1, 24, and 72 h. At time 0, the E-modulus was not affected by the adhesive system, whilst the degree of cure of CPB was higher than that of SBMP. Air storage increased the E-modulus at each ageing interval. Storage in water increased the E-modulus until it reached a maximum at 24 h, after which it decreased significantly at 72 h. No linear correlation between the percentage DC and E-modulus of the two adhesives was found when stored in water. The results of this study indicate that the mechanical properties and polymerization kinetics of SBMP and CPB are affected by storage time and medium. [source] Fabrication of a Macroporous Microwell Array for Surface-Enhanced Raman ScatteringADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Martina Zamuner Abstract Here, a colloidal templating procedure for generating high-density arrays of gold macroporous microwells, which act as discrete sites for surface-enhanced Raman scattering (SERS), is reported. Development of such a novel array with discrete macroporous sites requires multiple fabrication steps. First, selective wet-chemical etching of the distal face of a coherent optical fiber bundle produces a microwell array. The microwells are then selectively filled with a macroporous structure by electroless template synthesis using self-assembled nanospheres. The fabricated arrays are structured at both the micrometer and nanometer scale on etched imaging bundles. Confocal Raman microscopy is used to detect a benzenethiol monolayer adsorbed on the macroporous gold and to map the spatial distribution of the SERS signal. The Raman enhancement factor of the modified wells is investigated and an average enhancement factor of 4,×,104 is measured. This demonstrates that such nanostructured wells can enhance the local electromagnetic field and lead to a platform of ordered SERS-active micrometer-sized spots defined by the initial shape of the etched optical fibers. Since the fabrication steps keep the initial architecture of the optical fiber bundle, such ordered SERS-active platforms fabricated onto an imaging waveguide open new applications in remote SERS imaging, plasmonic devices, and integrated electro-optical sensor arrays. [source] A coordinated approach to cutaneous wound healing: vibrational microscopy and molecular biologyJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 5b 2008K. L. Andrew Chan Abstract The repair of cutaneous wounds in the adult body involves a complex series of spatially and temporally organized processes to prevent infection and restore homeostasis. Three characteristic phases of wound repair (inflammation, proliferation including re-epithelialization and remodelling) overlap in time and space. We have utilized a human skin wound-healing model to correlate changes in genotype and pheno-type with infrared (IR) and confocal Raman spectroscopic images during the re-epithelialization of excisional wounds. The experimental protocols validated as IR images clearly delineate the keratin-rich migrating epithelial tongue from the collagen-rich wound bed. Multivariate statistical analysis of IR datasets acquired 6 days post-wounding reveal subtle spectral differences that map to distinct spatial distributions, which are correlated with immunofluorescent staining patterns of different keratin types. Images computed within collagen-rich regions expose complementary spatial patterns and identify elastin in the wound bed. The temporal sequence of events is explored through a comparison of gene array analysis with confocal Raman microscopy. Our approach demonstrates the feasibility of acquiring detailed molecular structure information from the various proteins and their subclasses involved in the wound-healing process. [source] Development of clinical dosage forms for a poorly water-soluble drug II: Formulation and characterization of a novel solid microemulsion preconcentrate system for oral delivery of a poorly water-soluble drugJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2009Ping Li Abstract The solution of a poorly water-soluble drug in a liquid lipid,surfactant mixture, which served as a microemulsion preconcentrate, was converted into a solid form by incorporating it in a solid polyethylene glycol (PEG) matrix. The solid microemulsion preconcentrates thus formed consisted of Capmul PG8 (propylene glycol monocaprylate) as oil, Cremophor EL (polyoxyl 35 castor oil) as surfactant, and hydrophilic polymer PEG 3350 as solid matrix. The drug (aqueous solubility: 0.17 µg/mL at pH 1,8 and 25°C) was dissolved in a melt of the mixture at 65,70°C and then the hot solution was filled into hard gelatin capsules; the liquid gradually solidified upon cooling below 55°C. The solid system was characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), confocal Raman microscopy (CRM), and the dispersion testing in water. It was confirmed that a solid microemulsion preconcentrate is a two-phase system, where clusters of crystalline PEG 3350 formed the solid structure (m.p. 55,60°C) and the liquid microemulsion preconcentrate dispersed in between PEG 3350 crystals as a separate phase. The drug remained dissolved in the liquid phase. In vitro release testing showed that the preconcentrate dispersed readily in water forming a microemulsion with the drug dissolved in the oil particles (<150 nm) and the presence of PEG 3350 did not interfere with the process of self-microemulsification. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:1750,1764, 2009 [source] Crystallization pathways and kinetics of carbamazepine,nicotinamide cocrystals from the amorphous state by in situ thermomicroscopy, spectroscopy, and calorimetry studiesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2007K. Seefeldt Abstract The work presented here was motivated by the premise that the amorphous state serves as a medium to study cocrystal formation. The molecular mobility inherent to amorphous phases can lead to molecular associations between different components such that a single crystalline phase of multiple components or cocrystal is formed. Cocrystallization pathways and kinetics were investigated from amorphous equimolar phases of carbamazepine and nicotinamide using hot-stage polarized microscopy (HSPM), hot-stage Raman microscopy (HSRM), differential scanning calorimetry (DSC), and X-ray powder diffraction (XRPD). Nonisothermal studies revealed that amorphous phases generate cocrystals and that thermal history affects crystallization pathways in significant ways. Two different pathways to cocrystal formation from the amorphous phase were identified: (1) at low heating rates (3°C/min) a metastable cocrystalline phase initially nucleates and transforms to the more stable cocrystalline phase of CBZ,NCT, and (2) at higher heating rates (10°C/min) individual components crystallize, then melt and the stable cocrystalline phase nucleates and grows from the melt. Isothermal studies above the Tg of the amorphous equimolar phase also confirm the nucleation of a metastable cocrystalline phase from the amorphous state followed by a solid phase mediated transformation to the stable cocrystalline phase. Cocrystallization kinetics were measured by image analysis and by thermal analysis from small samples and are described by the Avrami,Erofeev model. These findings have important implications for the use of amorphous phases in the discovery of cocrystals and to determine the propensity of cocrystallization from process-induced amorphization. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 1147,1158, 2007 [source] Raman microscopy of the mixite mineral BiCu6(AsO4)3(OH)6·3H2O from the Czech RepublicJOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2010Ray L. Frost Abstract Raman microscopy of the mixite mineral BiCu6(AsO4)3(OH)6·3H2O from Jáchymov and from Smrkovec (both Czech Republic) has been used to study their molecular structure. The presence of (AsO4)3,, (AsO3OH)2,, (PO4)3, and (PO3OH)2, units, as well as molecular water and hydroxyl ions, was inferred. OH···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. Copyright © 2009 John Wiley & Sons, Ltd. [source] New trends and recent advances in coherent Raman microscopy and nonlinear optical spectroscopy: introduction to the special issueJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2009A. Volkmer Abstract This special issue highlights 20 papers, presenting the latest theoretical and experimental developments and achievements in coherent anti-Stokes Raman scattering (CARS) microscopy and nonlinear optical spectroscopy. Most of them were presented at the seventh European Conference on Nonlinear Optical Spectroscopy (ECONOS 2008) jointly held with the first European Conference on CARS Microscopy (microCARS 2008) in Igls, Austria, May 25,27, 2008. Copyright © 2009 John Wiley & Sons, Ltd. [source] Correlating Raman peak shifts with phase transformation and defect densities: a comprehensive TEM and Raman study on siliconJOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2009Thomas Wermelinger Abstract Silicon is the most often used material in micro electromechanical systems (MEMS). Detailed understanding of its mechanical properties as well as the microstructure is crucial for the reliability of MEMS devices. In this paper, we investigate the microstructure changes upon indentation of single crystalline (100) oriented silicon by transmission electron microscopy (TEM) and Raman microscopy. TEM cross sections were prepared by focused ion beam (FIB) at the location of the indent. Raman microscopy and TEM revealed the occurrence of phase transformations and residual stresses upon deformation. Raman microscopy was also used directly on the cross-sectional TEM lamella and thus microstructural details could be correlated to peak shape and peak position. The results show, however, that due to the implanted Ga+ ions in the lamella the silicon Raman peak is shifted significantly to lower wavenumbers. This hinders a quantitative analysis of residual stresses in the lamella. Furthermore, Raman microscopy also possesses the ability to map deformation structures with a lateral resolution in the submicron range. Copyright © 2009 John Wiley & Sons, Ltd. [source] Detection of explosives on human nail using confocal Raman microscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2009Esam M. A. Ali Abstract Trace amounts of explosives were detected on human nail using confocal Raman microscopy. Contamination of the nail can result from the manual handling, packaging or transportation of explosive substances. Raman spectra were obtained from pentaerythritol tetranitrate (PETN), trinitrotoluene (TNT), ammonium nitrate and hexamethylenetetramine (HMTA) particles on the surface of the nail with dimensions in the range 5,10 µm. An added difficulty in an analytical procedure is the presence of a nail varnish coating that has been applied, which traps the particulate matter between the coating and nail. Using confocal Raman microscopy, interference-free spectra could be acquired from particles of explosives visually masked by the nail varnish. Spectra of the explosives could be readily obtained in situ within 90 s without alteration of the evidential material. Acquisition of a Raman point map of a PETN particle under the nail varnish coating is also reported. Copyright © 2008 John Wiley & Sons, Ltd. [source] Raman spectroscopy in art and archaeologyJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2008Pietro Baraldi Abstract This paper introduces presentations given at the fourth International Conference on the Application of Raman Spectroscopy in Art and Archaeology, held in Modena, Italy, in the Ducal Palace, on 5,8 September 2007. The subjects of lectures and posters presented were concerned mainly with the new applications of Raman microscopy and other Raman techniques to more problematic samples, such as lakes, inks, and fluorescent dyes. Chronologically, the applications extended from the 10th century BC to the present day. The areas considered in the research were wide-ranging in terms of subject-matter and also geographically. New techniques have been developed for the study of binders in paintings and lakes, and with movable instrumentation on unmovable samples. Copyright © 2008 John Wiley & Sons, Ltd. [source] Pigment study by Raman microscopy of 23 paintings by the Portuguese artist Henrique Pousão (1859,1884)JOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2007Andreia M. Correia Abstract Twenty-three paintings by Henrique Pousão,a 19th century Portuguese painter,belonging to the collection of Museu Nacional Soares dos Reis, Porto, Portugal, were analysed by Raman microscopy. The fine focus of a 100× objective allowed the visualisation and individual identification of small grains. As a result, thirty-seven compounds, namely, anatase, barium white, basic lead sulfate, brochantite, cadmium red, cadmium yellow, calcium carbonate, carbon-based black, celadonite, chrome green, chrome orange, chrome yellow, cobalt blue, cochineal lake, copper sulfide, emerald green, iron(III) oxyhydroxide, iron(III) oxide, kaolinite, lead antimonate yellow, lead carbonate, lead white, lead sulfate, madder lake, malachite, Prussian blue, quartz, realgar/pararealgar, red lead, rutile, Scheele's green, strontium yellow, ultramarine blue, vermilion, viridian, zinc white and zinc yellow, were identified. Not all these compounds are pigments; some are extenders, others trace components and others probably products of reactions between pigments. Special attention was given to the Raman characterisation of celadonite, chrome orange, basic lead sulfate and lead antimonate yellow. Complementary techniques were used to confirm the identities of certain pigments and to characterise reference samples. Pousão, whose work has not previously been studied spectroscopically, was found to have used a remarkably wide range of pigments over his painting periods, without showing significant preference for any particular set of pigments. Copyright © 2007 John Wiley & Sons, Ltd. [source] An example of the complementarity of laser-induced breakdown spectroscopy and Raman microscopy for wall painting pigments analysisJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2007Romain Bruder Abstract Laser-induced breakdown spectroscopy (LIBS) and Raman microscopy were used for the identification of pigments in wall painting. Raman spectroscopy, which provides the molecular ,fingerprint' of the compound, is nowadays widely used by the archaeometry community, especially for pigment analysis. LIBS, which provides the elementary composition of samples, is a rapid noncontact method, enabling layer-by-layer analysis through a precise laser ablation of the sample. This work deals with the behavior of pigments after a LIBS analysis, by trying to identify the compounds before and after the laser shot. Six commercial pigments prepared with the fresco technique were investigated: ultramarine blue, red lead, charcoal, a yellow and a red ochre, and a green earth. Raman spectra, acquired on the sample surface and in the crater induced by LIBS analysis, were compared. The results show that these pigments are well recognized after a LIBS measurement. The analysis of green earth illustrates that the combination of these two techniques gives complete information from a sample. Copyright © 2007 John Wiley & Sons, Ltd. [source] Analysis of degraded papers by non-destructive spectroscopic techniquesJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2006Marina Bicchieri Abstract Scientific approach to cultural heritage conservation is very important for cultural reasons and also in order to avoid mistakes in restoration work. Acidity and oxidation play a very important role in paper conservation. Deacidification is a widely used method to remove acidity on aged papers, but if a large amount of carbonyl groups is present in the paper, a strong deacidification can promote an alkali-catalysed ,-alkoxy elimination, leading to the breaking of the anhydroglucose ring in the cellulose chain. In this case, and also in the case of non-acidic but oxidised papers, a reduction treatment is necessary. Because of the high costs of restoration procedures, it is essential to determine whether the reduction treatment is a primary need. In this work we report a study, based on micron-scale space resolved Raman microscopy, infrared reflectance spectroscopy and atomic force microscopy, of differently degraded samples of paper. Non-treated and oxidised samples were investigated, as well as original ancient documents. The aim of this work is to achieve a better understanding of the degradation pattern of historical samples in order to be able to choose the most appropriate restoration treatment using non-destructive spectroscopic techniques. Analysis of the samples demonstrates that degradation processes occur mainly on fibrils and on the fibre wall, as shown also by atomic force microscopy measurements. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Lindisfarne Gospels and two other 8th century Anglo-Saxon/Insular manuscripts: pigment identification by Raman microscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2004Katherine L. Brown Abstract The Lindisfarne Gospels (Cotton MS Nero D iv, ca. 715 AD) and two nearly contemporary manuscripts (Royal MS 1B vii and Add. MS 40618) held in the British Library have been analysed in detail by Raman microscopy in order to establish the palette of each. The blue pigment used on the Lindisfarne Gospels is shown not to be lazurite, as concluded in 1960 by visual examination of known pigments and those on the Gospels, but exclusively indigo. Of the Anglo-Saxon and Insular manuscripts studied so far by Raman microscopy, the earliest found to include lazurite in its palette is Add. MS 40618, not on its still extant original miniature of ca. 756 AD, but on later additions of ca. 920 AD. The Insular triumvirate palette, which had been assumed to consist of orpiment, red lead and verdigris, was found also to include red ochre and vergaut (indigo admixed with orpiment) but not necessarily verdigris. The palettes of the manuscripts studied, as specified in existing literary sources, are not reliable, and careful in situ scientific analysis of the pigments present is essential to establish the identity of the latter and of any decomposition products present. Copyright © 2004 John Wiley & Sons, Ltd. [source] Applicability of laser-induced Raman microscopy for in situ monitoring of imine formation in a glass microfluidic chipJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2003Moonkwon Lee Abstract Laser-induced Raman microscopy has been used to illustrate its applicability for the in situ monitoring of imine formation reaction in a glass microfluidic chip. In order to monitor the diffusion process in a micro channel, the Raman spectra were measured at various points along the channel with a constant flow rate of 2.7 µl min,1. Time-dependent Raman spectra were also measured without flow in order to monitor the variation of Raman peaks to a complete conversion. The disappearance of the CO stretching peak at 1700 cm,1 of the reactant, benzaldehyde, and the appearance of the Raman peak for the product, an imine, at 1628 cm,1 were successfully monitored. In addition, the intensity increases of three phenyl stretching modes in the 1550,1630 cm,1 region were also observed. The increase in Raman intensity for this vibrational mode is caused by an effective ,-electron conjugation between two phenyl rings through the ,CN,bridging group of the product. Laser-induced Raman microscopy enables us to monitor in situ product formation and to obtain detailed structural information in a glass microfluidic chip. Copyright © 2003 John Wiley & Sons, Ltd. [source] Molecular structure of the adelite group of minerals,a Raman spectroscopic studyJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2003Wayde Martens Abstract The application of Raman microscopy to the study of closely related mineral phases of the adelite group has allowed their molecular characterization. The adelite group of minerals are orthorhombic arsenates and vanadates of general formula AB2+ (XO4)(OH), where X may be As5+ or V5+, cation A may be Ca or Pb and cation B may be Co or Cu and others. Raman spectroscopy has proven most powerful for the identification of these minerals. In particular, the position of the hydroxyl stretching vibrations and most of the arsenate bands have been identified. The two minerals tangeite and calciovolborthite have previously been identified as the same mineral. Raman spectroscopy has proven that the minerals are not identical and have different structures. The application of Raman spectroscopy to the study of these minerals shows that increased distortion of the arsenate anion occurs as the cationic substitution from conichalcite to austinite to duftite occurs. Copyright © 2003 John Wiley & Sons, Ltd. [source] Structured water in hydrotalcites of formula MgxZn6,xAl2(OH)16(CO3)·4H2O: a Raman microscopic studyJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2002Therese E. Johnson Raman microscopy was used to characterize synthesized hydrotalcites of formula MgxZn6,xAl2(OH)16 (CO3)·4H2O. The Raman spectra are conveniently subdivided into spectral features based on (a) the carbonate anion, (b) the hydroxyl units and (c) metal,oxygen units. A model is proposed based on a tripod of M3OH units in the hydrotalcite structure. In a simplified model, Raman spectra of the hydroxyl-stretching region enable bands to be assigned to the Mg3OH, Zn3OH and Al3OH units. Bands are also assigned to the hydroxyl stretching vibrations of water. Three types of water are identified: (a) water hydrogen bonded to the interlayer carbonate ion, (b) water hydrogen bonded to the hydrotalcite hydroxyl surface and (c) interlamellar water. A model of water in the hydrotalcite structure is proposed in which water is in a highly ordered structure as it is hydrogen bonded to both the carbonate anion and the hydroxyl surface and also forms bridges between the MOH surface and the carbonate anion. Copyright © 2002 John Wiley & Sons, Ltd. [source] Comparison of genuine (1851,1852 AD) and forged or reproduction Hawaiian Missionary stamps using Raman microscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2002Tracey D. Chaplin The rare and valuable Hawaiian Missionary stamps from the Tapling Collection held at the British Library were analysed using Raman microscopy and shown to be printed with an ink composed of Prussian blue. Blue particles dispersed between the paper fibres of the stamps and present as optical brighteners were identified to be lazurite or the synthetic equivalent, ultramarine blue. Each cancellation or postmark, where present, is composed of carbon, vermilion, iron(III) oxide or a madder-like organic pigment. The Raman analysis also showed that microscopic repair work on stamps can be identified. The genuine stamps were compared with 13 forged Hawaiian Missionary stamps, printed in the early 20th century, and with a set of eight reproduction items printed in 1985, from the Royal Philatelic Society London. Raman analysis of the forged stamps showed that the ink used is different from that of the genuine stamps, being a mixture of Prussian blue and ultramarine blue, or an organic blue pigment. Analysis of the 1985 reproduction stamps showed that they were printed with modern phthalocyanine blue ink, on paper coated with a yellow organic pigment to simulate aged paper. This analysis provides an invaluable and non-destructive method for assisting in drawing a distinction between fraudulent or reproduction material and the genuine article. Copyright © 2002 John Wiley & Sons, Ltd. [source] Raman microscopy of formamide-intercalated kaolinites treated by controlled-rate thermal analysis technologyJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2001Ray L. Frost Raman spectroscopy of formamide-intercalated kaolinites treated using controlled-rate thermal analysis technology (CRTA), allowing the separation of adsorbed formamide from intercalated formamide in formamide-intercalated kaolinites, is reported. The Raman spectra of the CRTA-treated formamide-intercalated kaolinites are significantly different from those of the intercalated kaolinites, which display a combination of both intercalated and adsorbed formamide. An intense band is observed at 3629 cm,1, attributed to the inner surface hydroxyls hydrogen bonded to the formamide. Broad bands are observed at 3600 and 3639 cm,1, assigned to the inner surface hydroxyls, which are hydrogen bonded to the adsorbed water molecules. The hydroxyl-stretching band of the inner hydroxyl is observed at 3621 cm,1 in the Raman spectra of the CRTA-treated formamide-intercalated kaolinites. The results of thermal analysis show that the amount of intercalated formamide between the kaolinite layers is independent of the presence of water. Significant differences are observed in the CO stretching region between the adsorbed and intercalated formamide. Copyright © 2001 John Wiley & Sons, Ltd. [source] Low-Temperature Aging of Zirconia Ferrules for Optical ConnectorsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2001Michael J. Lance Zirconia ferrules for optical connectors were examined after aging at 85°C and 95% relative humidity. Two degradation mechanisms were the roughening and the deformation of the zirconia ferrule surface. Raman microscopy revealed that this relatively low-temperature degradation of zirconia ferrules is caused by the tetragonal to monoclinic transformation of zirconia, and is accelerated by stress relief during polishing. The surface upheavals associated with low-temperature aging may significantly degrade the performance of optical connectors over time. [source] Extent of thermal ablation suffered by model organic microparticles during aerogel capture at hypervelocitiesMETEORITICS & PLANETARY SCIENCE, Issue 10 2009M. J. Burchell Commercial polystyrene particles (20 ,m diameter) were coated with an ultrathin 20 nm overlayer of an organic conducting polymer, polypyrrole. This overlayer comprises only 0.8% by mass of the projectile but has a very strong Raman signature, hence its survival or destruction is a sensitive measure of the extent of chemical degradation suffered. After aerogel capture, microparticles were located via optical microscopy and their composition was analyzed in situ using Raman microscopy. The ultrathin polypyrrole overlayer survived essentially intact for impacts at ,1 km s,1, but significant surface carbonization was found at 2 km s,1, and major particle mass loss at ,3 km s,1. Particles impacting at ,6.1 km s,1 (the speed at which cometary dust was collected in the NASA Stardust mission) were reduced to approximately half their original diameter during aerogel capture (i.e., a mass loss of 84%). Thus significant thermal ablation occurs at speeds above a few km s,1. This suggests that during the Stardust mission the thermal history of the terminal dust grains during capture in aerogel may be sufficient to cause significant processing or loss of organic materials. Further, while Raman D and G bands of carbon can be obtained from captured grains, they may well reflect the thermal processing during capture rather than the pre-impact particle's thermal history. [source] Proteins can convert to ,-sheet in single crystalsPROTEIN SCIENCE, Issue 5 2004Run Zheng TC: transcarboxylase; 5S: a subunit of TC that carboxylates pyruvate; 12S: a subunit of TC that transfers carboxylate from methylmalonyl-CoA to biotin; Ni-NTA: a nickel-charged agarose resin Abstract Raman microscopy was used to follow conformational changes in single protein crystals. Crystals of native insulin and of the 5S and 12S subunits of the enzyme transcarboxylase showed a mixture of Raman marker bands signifying ,-helix, ,-sheet and nonordered secondary structure. However, by reducing the S,S bonds in the insulin crystal, or by lowering the pH for the 5S crystal, or by soaking substrates into the 12S crystal, the secondary structure in each crystal became predominantly ,-sheet. The ,-form crystals could be dissolved only with difficulty and yielded high,molecular weight protein aggregates, indicating that the ,-sheet formation involves intermolecular contacts. Although their morphology appeared unchanged, the crystals no longer diffracted X-rays. Using crystals that had not been exposed to laser light, the dye thioflavin T formed highly fluorescent complexes with the ",-transformed" crystals but not with the native crystals. [source] Raman Spectroscopic Analysis of Ancient Egyptian PigmentsARCHAEOMETRY, Issue 4 2001A. Rosalie David The application of FT-Raman spectroscopy and visible Raman microscopy to the non-destructive analysis of pigment specimens excavated from Tell el Amarna by Flinders Petrie in the 1890s has provided information about the chemical composition of the materials used by XVIIIth Dynasty artists in the New Kingdom at the time of King Akhenaten, c. 1340 bc. Comparison of the Raman spectra of the samples labelled ,red and yellow ochre' with documented, archival material from geological collections provided a clear indication of the materials used in the iron(III) oxide/hydroxide system, including ,-hematite, goethite, maghemite, magnetite and lepidocrocite. The yellow,orange specimen labelled ,realgar' proved to be a mixture of realgar and pararealgar; since the specimen had been sheltered from light since its excavation, this could indicate that the ancient Egyptian artists recognized the colour variation and may have used this to effect in their decorations. A specimen of yellow ochre contained goethite, ,-FeO.OH, with particles of crystalline, highly ordered graphite; in contrast, the red ochre specimens contained amorphous carbon particles. [source] Confocal Raman Microscopy as a Tool to Investigate Concentration Profiles of Melt Crystallized Ibuprofen/Carnauba WaxCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2009H. Qu Abstract Coatings are of great significance for pharmaceutical solid dosage forms. They fulfil a number of functions and are often necessary to control drug delivery, to mask bitter taste, or to protect the active pharmaceutical ingredient from detrimental environmental factors. The process of self-coating by melt crystallization of a suitable binary mixture eliminates the need for an additional process step in the manufacture of a solid drug. Self-coating relies upon the physical and spatial separation of individual components in a melt during solidification. This paper focuses on the use of confocal Raman microscopy as a nondestructive technique for quantifying the spatial distribution of the components in self-coated pastilles manufactured from the binary system ibuprofen/carnauba wax. Pastilles are produced from the melt. Raman spectroscopy allows the direct analysis of concentration profiles across the surface of the pastille. Here, the samples are cleaved and the cleaved surface is investigated in order to establish the distribution of the components in the interior of the solid. A univariate calibration model was developed and statistically validated with standard mixtures of ibuprofen and carnauba wax. Different regression models (linear or polynomial, using different significant peaks for the respective compounds) were assessed and a linear model was found to be adequate to determine the concentration gradient in the pastilles. [source] | |||||||||||||||||||