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941.
Daniela Schlemmer E. R. de Oliveira M. J. Araújo Sales 《Journal of Thermal Analysis and Calorimetry》2007,87(3):635-638
Conventional plastics has a
large impact in increasing the environment’s pollution. That’s
why the interest has turned towards novel partially and completely biodegradable
polymers. In this work, blends of polystyrene and thermoplastic starch with
glycerol and Buriti (Mauritia flexuosa
L.) oil as plasticizers were prepared. Samples were analyzed using TG/DTG
and DSC techniques. The TG results indicated that the blends with Buriti oil
are thermally more stable than those with glycerol. The DSC analysis that
Buriti oil provides a higher degree of plasticization of PS, compared to the
blends plasticized using glycerol under the studied conditions. 相似文献
942.
943.
A novel 14-membered macrocyclic Schiff base derived from 3-cinnamalideneacetoacetanilide and o-phenylenediamine acts as a tetradentate and strongly conjugated ligand to form a cationic solid complex with CuCl2/NiCl2/CoCl2/ZnCl2. The ligand and the complexes were characterized by the usual spectral and analytical techniques. The main i.r. band of the macrocyclic Schiff base was compared to that of its metal complexes. The C=N bands are shifted to the lower wave number. The cyclic voltammogram of the copper complex shows that the macrocyclic ligand is able to stabilize the copper(III) oxidation state. The e.s.r. spectra of the copper complex in DMSO solution at room temperature and liquid N2 temperature were recorded and their salient features thoroughly discussed. The antimicrobial screening tests were also recorded and gave good results in the presence of metal ions in the ligand system. 相似文献
944.
Jaime González Velasco 《Central European Journal of Chemistry》2005,3(3):470-481
The analytical treatment of a model considering the electrooxidation of p-porous silicon layers under galvanostatic conditions
is able to give account of experimental facts such as the shape and location of the electroluminescence peak as well as of
the spectral shift of the electroluminescence peak produced by oxidation. The proposed model considers electroluminescence
to be the result of electron injection into the conduction band by an adsorbed intermediate produced by electrooxidation of
the surface coverage with hydrogen or siloxene of the silicon nanocrystallites. The access of holes to the surface is made
possible by low accumulation layer conditions and is the rate determining step in the electroluminescence mechanism. In this
way it is possible to give a satisfactory explanation to the shift towards the blue experimented by the electroluminiscence
emission maximum as a consequence of electrooxidation. 相似文献
945.
V. V. Barbakadze E. P. Kemertelidze I. Targamadze K. Mulkidzhanyan J. Kemink A. J. J. van den Berg K. J. Beukelman A. I. Usov 《Chemistry of Natural Compounds》2005,41(4):374-377
Two high-molecular-weight (>1000 kDa) water-soluble preparations were isolated from stems of Symphytum asperum and S. caucasicum. Their basic component was established as poly[hydroxy-1-carboxy-2-(3,4-dihydroxyphenyl)ethylene], analogous to that of high-molecular-weight
(>1000 kDa) preparations from roots of these same plants, using IR and NMR spectral data.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 303–305, July–August, 2005.
An erratum to this article is available at . 相似文献
946.
The new monoterpenoid 5-isobutyl-3-methyl-2-furancarbaldehyde was isolated from Tagetes glandulifera Schrank and its structure confirmed by synthesis. 相似文献
947.
John T. Gupton John E. Gall Steve W. Riesinger Stanton Q. Smith Kathy M. Bevirt James A. Sikorski Maria L. Dahl Zdenek Arnold 《Journal of heterocyclic chemistry》1991,28(5):1281-1285
An alternative preparation of a 2-iminovinamidinium salt from phosphonoacetic acids is described along with its application to the synthesis of 5-formylpyrimidines and masked 4-formylpyrazoles. 相似文献
948.
Stephen de Mora Jean-Pierre Villeneuve Eric Wyse 《Accreditation and quality assurance》2007,12(11):587-592
Aspects of the International Atomic Energy Agency (IAEA) Analytical Quality Control Services (AQCS) for marine environmental
studies are discussed, focusing on recent laboratory performance studies (LPS) and the production of reference materials for
trace metals and organic compounds in various marine matrices. The IAEA has organized seventeen global interlaboratory studies
for a range of organic contaminants. Of note has been the inclusion of numerous polychlorinated biphenyl congeners (PCBs)
and some sterols of anthropogenic origin. Concurrently, there have been eleven worldwide intercomparison exercises for trace
metals in the marine environment, most of which included methylmercury. Although such interlaboratory studies can help improve
performance in individual laboratories and regional laboratory networks, the results reveal that problems remain in the determination
of some metals and many organic contaminants. 相似文献
949.
Summary. An efficient direct conversion of THP ethers into the corresponding acetates was achieved with acetic anhydride in the presence of CuSO4 · 5H2O as an available and green catalyst in high yields. 相似文献
950.
54Mn is analyzed in complex food ash of high cationic environment. The initial step is an extraction atpH 2.7 with hexane containing di(2-ethylhexyl) phosphoric acid (HDEHP) to complex the54Mn and other nuclides. The manganese is reextracted into an alkaline EDTA buffer which is washed with 1% 8-hydroxyquinoline
in chloroform containing 5% isoamyl alcohol. The54Mn is determined by gamma spectrometry with recoveries ranging from 96.6 to 99.4%. 相似文献