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Raman Spectrometry (raman + spectrometry)

Distribution by Scientific Domains

Polymers and Materials Science	40%
Earth and Environmental Science	40%

Selected Abstracts

Primary carbonate/CO2 inclusions in sapphirine-bearing granulites from central Sri Lanka

JOURNAL OF METAMORPHIC GEOLOGY, Issue 3 2000
Bolder-Schrijver
High-density CO2 -rich fluid inclusions from a sapphirine-bearing granulite (Hakurutale, Sri Lanka) have been studied by microthermometry, Raman spectrometry and SEM analysis. Based on textural evidence, two groups of inclusions can be identified: primary, negative crystal shaped inclusions (group I) and pseudo-secondary inclusions, which experienced a local, limited post-trapping modification (group II). Both groups contain magnesite as a daughter mineral, occurring in a relatively constant fluid/solid inclusion volume ratio (volsolid =0.15 total volume). CO2 densities for group I and II differ only slightly. Both groups contain a fluid, which was initially trapped at peak metamorphic conditions as a homogeneous (CO2+MgCO3) mixture. Thermodynamic calculations suggest that such a fluid (CO2+15 vol% MgCO3) is stable under granulite facies conditions. After trapping, magnesite separated upon cooling, while the remaining CO2 density suffered minor re-adjustments. A model isochore based on the integration of the magnesite molar volume in the CO2 fluid passes about 1.5,2 kbar below peak metamorphic conditions. This remaining discrepancy can be explained by the possible role of a small quantity of additional water. [source]

Piroxicam/2-hydroxypropyl-,-cyclodextrin inclusion complex prepared by a new fluid-bed coating technique

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2009
Xingwang Zhang
Abstract This work was aimed at investigating the feasibility of fluid-bed coating as a new method to prepare cyclodextrin inclusion complex. The inclusion complex of the model drug piroxicam (PIX) and 2-hydroxypropyl-,-cyclodextrin (HPCD) in aqueous ethanol solution was sprayed and deposited onto the surface of the pellet substrate upon removal of the solvent. The coating process was fluent with high coating efficiency. Scanning electron microscopy revealed a coarse pellet surface, and a loosely packed coating structure. Significantly enhanced dissolution, over 90% at 5 min, was observed at stoichiometric PIX/HPCD molar ratio (1/1) and at a ratio with excessive HPCD (1/2). Differential scanning calorimetry and powder X-ray diffractometry confirmed absence of crystallinity of PIX at PIX/HPCD molar ratio of 1/1 and 1/2. Fourier transform-infrared spectrometry and Raman spectrometry revealed interaction between PIX and HPCD adding evidence on inclusion of PIX moieties into HPCD cavities. Solid-state 13C NMR spectrometry indicated possible inclusion of PIX through the pyridine ring. It is concluded that fluid-bed coating has potential to be used as a new technique to prepare cyclodextrin inclusion complex. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:665,675, 2009 [source]

Selective migration in polyethylene/rubbery particles blends during capillary flow

POLYMER ENGINEERING & SCIENCE, Issue 4 2010
C. Chartier
Adding elastomeric particles (Sunigum®) into a polyethylene (PE) matrix leads to an increase of both viscosity and dynamic moduli in the molten state. This suspension effect is more pronounced if the particle's dispersion is improved with a compatibilizing agent. However, under capillary flow, the blends exhibit a more complex behavior with a strong violation of a viscosity mixing rule. To elucidate the origin of this observation, an analysis of extrudates by confocal micro Raman spectrometry has been carried out. A selective migration of the lowest viscosity component (at a given shear rate) toward the wall of the capillary die has been noted. This migration is inhibited by the addition of a compatibilizer. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers [source]

Gas Hydrates in the Qilian Mountain Permafrost, Qinghai, Northwest China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010
Youhai ZHU
Abstract: Qilian Mountain permafrost, with area about 10×104 km2, locates in the north of Qinghai-Tibet plateau. It equips with perfect conditions and has great prospecting potential for gas hydrate. The Scientific Drilling Project of Gas Hydrate in Qilian Mountain permafrost, which locates in Juhugeng of Muri Coalfield, Tianjun County, Qinghai Province, has been implemented by China Geological Survey in 2008,2009. Four scientific drilling wells have been completed with a total footage of 2059.13 m. Samples of gas hydrate are collected separately from holes DK-1, DK-2 and DK-3. Gas hydrate is hosted under permafrost zone in the 133,396 m interval. The sample is white crystal and easily burning. Anomaly low temperature has been identified by the infrared camera. The gas hydrate-bearing cores strongly bubble in the water. Gas-bubble and water-drop are emitted from the hydrate-bearing cores and then characteristic of honeycombed structure is left The typical spectrum curve of gas hydrate is detected using Raman spectrometry. Furthermore, the logging profile also indicates high electrical resistivity and sonic velocity. Gas hydrate in Qilian Mountain is characterized by a thinner permafrost zone, shallower buried depth, more complex gas component and coal-bed methane origin etc. [source]

Effect of Substrate Temperature on the Plasma Polymerization of Poly(methyl methacrylate),

CHEMICAL VAPOR DEPOSITION, Issue 1 2006
B. Casserly
Abstract Low-power, plasma-enhanced (PE)CVD together with polymerization of methyl methacrylate (MMA) can be used to deposit thin films of poly(methyl methacrylate) (PMMA) with,minimal loss of functional groups, as shown by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and Raman spectrometry (RS). Retention of functional groups decreases with increased substrate temperature, corresponding to decreased deposition rates. From XPS data, the calculated percentage loss of functional groups ranges from 0.9,% to 43.4,%, changing as a function of deposition conditions. RS confirms the presence of C=C bonds in the polymer backbone as a result of scission of the ester group from MMA. The thermal properties of PECVD-produced films from MMA can be tailored by varying the substrate temperature. Onset of thermal decomposition increases with increased substrate temperature by eliminating thermally labile peroxide linkages in the polymer backbone, and by crosslinking that occurs at radical sites generated via scission of functional group bonds. The post-anneal thicknesses of the remaining polymer is of the order of 4,nm or less, indicating that low-power PECVD of PMMA is a viable candidate to act as a sacrificial material for air-gap fabrication. [source]