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641.
Quality assurance and quality control for thermal/optical analysis of aerosol samples for organic and elemental carbon 总被引:1,自引:0,他引:1
Chow JC Watson JG Robles J Wang X Chen LW Trimble DL Kohl SD Tropp RJ Fung KK 《Analytical and bioanalytical chemistry》2011,401(10):3141-3152
Accurate, precise, and valid organic and elemental carbon (OC and EC, respectively) measurements require more effort than
the routine analysis of ambient aerosol and source samples. This paper documents the quality assurance (QA) and quality control
(QC) procedures that should be implemented to ensure consistency of OC and EC measurements. Prior to field sampling, the appropriate
filter substrate must be selected and tested for sampling effectiveness. Unexposed filters are pre-fired to remove contaminants
and acceptance tested. After sampling, filters must be stored in the laboratory in clean, labeled containers under refrigeration
(<4 °C) to minimize loss of semi-volatile OC. QA activities include participation in laboratory accreditation programs, external
system audits, and interlaboratory comparisons. For thermal/optical carbon analyses, periodic QC tests include calibration
of the flame ionization detector with different types of carbon standards, thermogram inspection, replicate analyses, quantification
of trace oxygen concentrations (<100 ppmv) in the helium atmosphere, and calibration of the sample temperature sensor. These
established QA/QC procedures are applicable to aerosol sampling and analysis for carbon and other chemical components. 相似文献
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644.
Jhillu S. Yadav Author Vitae Aneesh Antony Author VitaeAuthor Vitae Basi V. Subba Reddy Author Vitae 《Journal of organometallic chemistry》2011,696(1):16-36
The electrophilic activation(C-H activation) of alkenes by transition metal catalysts is a fundamental step in a rapidly growing number of catalytic processes since it would provide simple, clean, and economic methods for making controlled and selectively functionalized organic moieties directly from simple olefins. Also catalytic activation of C-H bonds leading to useful organic reactions such as new C-C, C-N and C-O bond formation is of considerable interest for the chemical and pharmaceutical industries and remained a long-term challenge to chemists. A substantial progress has made in the last decade in this area. Contrary to traditional belief, it is nowadays possible to control the regiochemistry of various additions of nucleophiles to alkenes by the choice of transition metal catalysts. Atom economy, an inevitable factor of current research also can be accomplished in these reactions. Developments in this area of selective hydrofunctionalisation of alkenes by taking into consideration of the mechanistic aspects and the role of organometallic catalyst or active species formed during the reaction on the outcome of the reactions are reviewed. 相似文献
645.
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Raman and FTIR spectra of CaFeTi(PO4)3 and CdFeTi(PO4)3 are recorded and analyzed. The observed bands are assigned in terms of vibrations of TiO6 octahedra and PO4 tetrahedra. The symmetry of TiO6 octrahedra and PO4 tetrahedra is lowered from their free ion symmetry. The presence of Fe3+ ion disrupts the Ti-O-P-O-Ti chain and leads to the distortion of TiO6 octrahedra and PO4 tetrahedra. The PO43− tetrahedra in both crystals are linearly distorted. The covalency bonding factor of PO43− polyanion of both the crystals are calculated from the Raman spectra and compared to that of other Nasicon-type systems. The numerical values of covalency bonding factor indicates that there is a reduction in redox energy and cell voltage and is attributed to strong covalency of PO43− polyanionin. 相似文献
647.
K. K. Abdullah N. Ramachandran K. Karunakaran Nair B. R. S. Babu Antony Joseph Rajive Thomas K. M. Varier 《Pramana》2008,70(4):633-641
We have carried out photon attenuation measurements at several energies in the range from 49.38 keV to 57.96 keV around the
K-absorption edges of the rare earth elements Sm, Eu, Gd, Tb, Dy and Er using 59.54 keV gamma rays from 241Am source after Compton scattering from an aluminium target. Pellets of oxides of the rare earth elements were chosen as mixture
absorbers in these investigations. A narrow beam good geometry set-up was used for the attenuation measurements. The scattered
gamma rays were detected by an HPGe detector. The results are consistent with theoretical values derived from the XCOM package.
相似文献
648.
Study of the surface morphology of polyisobutylene-based block copolymers by atomic force microscopy
Judit E. Puskas Prince Antony Yongmoon Kwon Milan Kovar Peter R. Norton 《Macromolecular Symposia》2002,183(1):191-198
This paper reports the investigation of the nanostructured surface morphology of linear polystyrene-block-polyisobutylene-block-polystyrene (SIBS) triblock copolymers and novel arborescent SIBS block copolymers by Atomic Force Microscopy (AFM) in the tapping mode. Thin films spin coated from toluene onto silicon wafers were studied. The nanostructured morphology of the block copolymers varied with the hard polystyrene (PS) and soft polyisobutylene (PIB) segment composition, ranging from spherical to lamellar nanometer-sized discreet PS phases dispersed in a continuous PIB matrix. Annealing the samples resulted in well developed/ordered structures. The arborescent blocks had irregularly distributed PS phases in the PIB matrix. Annealing had a dramatic effect on the morphology which still remained irregular. Three-dimensional AFM image and section analysis indicated the presence of a height difference between PIB (high-lying plateaus or hills) and PS (low-lying plateaus or valleys) in the block copolymers, which became more prominent during annealing. It is theorized that the rubbery PIB chains are able to relax, thereby protruding from the surface, anchored by the physically crosslinked PS phases. 相似文献
649.
Bennie R. Biju Joel C. Raj A. Nirmal Paul Antony A. Jerold Pillai S. Iyyam 《Journal of Solid State Electrochemistry》2023,27(1):271-280
Journal of Solid State Electrochemistry - The growing demand for electricity has increased the interest of the researchers towards exploration of energy storing devices (ESDs). With the motif for... 相似文献
650.
Dendritic growth of potassium dihydrogen phosphate (KDP) crystals in silica gels at room temperature is reported. Branching along directions perpendicular to the arms and dendrites growing in mutually perpendicular 〈100〉 and 〈010〉 directions are illustrated. Initial stages and surface of a dendrite are illustrated and described. Also explained are the crystallites growing on the dendrite which finally lead to the formation of platelets. 相似文献