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Nahar Singh VN Ojha Nijhuma Kayal Tarushee Ahuja Prabhat K Gupta 《Chemistry Central journal》2011,5(1):17
Arsenic is the toxic element, which creates several problems in human being specially when inhaled through air. So the accurate
and precise measurement of arsenic in suspended particulate matter (SPM) is of prime importance as it gives information about
the level of toxicity in the environment, and preventive measures could be taken in the effective areas. Quality assurance
is equally important in the measurement of arsenic in SPM samples before making any decision. The quality and reliability
of the data of such volatile elements depends upon the measurement of uncertainty of each step involved from sampling to analysis.
The analytical results quantifying uncertainty gives a measure of the confidence level of the concerned laboratory. So the
main objective of this study was to determine arsenic content in SPM samples with uncertainty budget and to find out various
potential sources of uncertainty, which affects the results. Keeping these facts, we have selected seven diverse sites of
Delhi (National Capital of India) for quantification of arsenic content in SPM samples with uncertainty budget following sampling
by HVS to analysis by Atomic Absorption Spectrometer-Hydride Generator (AAS-HG). In the measurement of arsenic in SPM samples
so many steps are involved from sampling to final result and we have considered various potential sources of uncertainties.
The calculation of uncertainty is based on ISO/IEC17025: 2005 document and EURACHEM guideline. It has been found that the
final results mostly depend on the uncertainty in measurement mainly due to repeatability, final volume prepared for analysis,
weighing balance and sampling by HVS. After the analysis of data of seven diverse sites of Delhi, it has been concluded that
during the period from 31st Jan. 2008 to 7th Feb. 2008 the arsenic concentration varies from 1.44 ± 0.25 to 5.58 ± 0.55 ng/m3 with 95% confidence level (k = 2). 相似文献
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DS Zhulai SA Bugaychuk GV Klimusheva TA Mirnaya VN Asaula VI Handziuk 《Liquid crystals》2017,44(8):1269-1276
The class of thermotropic ionic liquid crystals (LCs) of the metal alkanoates possesses a number of unique properties, such as intrinsic ionic conductivity, high dissolving ability and ability to form time-stable mesomorphic glasses. These ionic LCs can be used as nanoreactors for the synthesis and stabilisation of different types of nanoparticles (NPs). Thus, some semiconductors, metals and core/shell NPs were chemically synthesised in the thermotropic ionic liquid crystalline phase (smectic A) of the cadmium octanoate (CdC8) and of the cobalt octanoate (CoC8). By applying the scanning electron microscopy, the cadmium and cobalt octanoate composites containing CdS, Au, Ag and core/shell Au/CdS NPs have been studied. NPs’ sizes and dispersion distribution of the NPs’ size in the nanocomposites have been obtained. 相似文献
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Rüba E Mereiter K Schmid R Supunov VN Kirchner K Schottenberger H Calhorda MJ Veiros LF 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(17):3948-3961
The reaction of alkynes with [RuCp(PR(3))(CH(3)CN)(2)]PF(6) (R=Me, Ph, Cy) affords, depending on the structure of the alkyne and the substituent of the phosphine ligand, allyl carbene or butadienyl carbene complexes. These reactions involve the migration of the phosphine ligand or a facile 1,2 hydrogen shift. Both reactions proceed via a metallacyclopentatriene complex. If no alpha C[bond]H bonds are accessible, allyl carbenes are formed, while in the presence of alpha C[bond]H bonds butadienyl carbenes are typically obtained. With diphenylacetylene, on the other hand, a cyclobutadiene complex is formed. A different reaction pathway is encountered with HC[triple bond]CSiMe(3), ethynylferrocene (HC[triple bond]CFc), and ethynylruthenocene (HC[triple bond]CRc). Whereas the reaction of [RuCp(PR(3))(CH(3)CN)(2)]PF(6) (R=Ph and Cy) with HC[triple bond]CSiMe(3) affords a vinylidene complex, with HC[triple bond]CFc and HC[triple bond]CRc this reaction does not stop at the vinylidene stage but subsequent cycloaddition yields allenyl carbene complexes. This latter C[bond]C bond formation is effected by strong electronic coupling of the metallocene moiety with the conjugated allenyl carbene unit, which facilitates transient vinylidene formation with subsequent alkyne insertion into the Ru[double bond]C bond. The vinylidene intermediate appears only in the presence of bulky substituents of the phosphine coligand. For the small R=Me, head-to-tail coupling between two alkyne molecules involving phosphine migration is preferred, giving the more usual allyl carbene complexes. X-ray structures of representative complexes are presented. A reasonable mechanism for the formation of both allyl and allenyl carbenes has been established by means of DFT calculations. During the formation of allyl and allenyl carbenes, metallacyclopentatriene and vinylidene complexes, respectively, are crucial intermediates. 相似文献
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