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61.
Bioremediation of toluene and naphthalene in liquid cultures of bacteria grown in the presence of these aromatic compounds as unique sources of carbon was investigated by gas chromatography (GC). For this purpose, a method based on the use of GC with flame ionization detection was developed and validated. Validation was carried out in terms of limit of detection (LOD), limit of quantitation (LOQ), linearity, precision and trueness. In the case of naphthalene, LOD and LOQ values of 0.43 and 0.72 mg kg(-1) were achieved. Linearity was established over one order of magnitude in the range of interest, i.e. 10-100 mg kg(-1). Excellent precision was obtained both in terms of intra-day repeatability and between-day precision on two concentration levels (RSD% lower than 0.5%). A recovery of 97.9 +/- 0.2% (n=3) was calculated by addition of 640 mg kg(-1) of naphthalene to the Bushnell & Haas mineral salts basal solution containing the micro-organisms. Findings clearly showed a reduction of the naphthalene content equal to 50% and 75% after two and four weeks of contact with the micro-organisms, whereas a lower degradation was shown in the case of toluene. Finally bioremediation activity was ascribed to two different microbial populations, Bordetella Petrii and Bacillus Sphericus, which survived in the polluted medium. 相似文献
62.
Z. Moldovan L. Alexandrescu I. Vasilescu L. Radu 《Journal of the Iranian Chemical Society》2006,3(4):305-311
The title compound, 1,2-dihydro-2,2,4-trimethylquinoline (TMQ), is a quinoline family member and is among others used to prevent the oxidative degradation of polymers. TMQ has been characterized by its fluorescence emission. In this work the effects of solvent, acidity, continuous irradiation and the influence of some interferents upon the fluorescence intensity of TMQ were investigated. Under the selected conditions (in propan-1-ol solution at λexcitation/λemission = 334 nm/412 nm), the fluorescence intensity is proportional to the concentration of TMQ over the range 0.05–5 μg ml?1 with a correlation coefficient of 0.9963. The proposed method was applied to the determination of TMQ in synthetic mixtures of polymer additives and specific rubber samples. 相似文献
63.
64.
Andrea Melchior Marilena Tolazzi Silvia Del Piero 《Journal of Thermal Analysis and Calorimetry》2011,103(1):35-40
The complex formation of Cd(II) with N-donor ligands in dimethylsulfoxide (DMSO) is investigated by means of potentiometry
and titration calorimetry. The ligands considered in this work are tripodal polyamines and polypyridines: 2,2′,2″-triaminotriethylamine
(TREN), tris(2-(methylamino)ethyl)amine (Me3TREN), tris(2-(dimethylamino)ethyl)amine (Me6TREN), tris[(2-pyridyl)methyl]amine (TPA) and 6,6′-bis-[bis-(2-pyridylmethyl)aminomethyl]-2,2′-bipyridine (BTPA). These ligands
are characterized by a systematic modification of the donor groups to relate their structure to the thermodynamics of the
complexes formed. The TREN and Me3TREN ligands form highly stable species. The stability of the complex formed with the fully methylated Me6TREN is much lower than with other polyamines and the enthalpic and entropic terms suggest an incomplete coordination to the
metal ion. In general, the TPA ligand forms complexes less stable than TREN and Me3TREN as a result of the combination of higher structural rigidity of TPA and lower basicity of pyridine moiety with respect
to primary and secondary amines. Pyridine-containing ligands display, in general, a less unfavorable formation entropy than
tripodal polyamines here considered. In particular, TPA forms a more stable 1:1 species with respect to Me6TREN due to the entropic term, being the enthalpy less negative. The ligand BTPA is able to form only a monometallic complex,
where the metal ion is likely to be encapsulated as indicated by the obtained thermodynamic parameters. 相似文献
65.
Cunden Fabio Deelan Facchi Paolo Ligabò Marilena Vivo Pierpaolo 《Journal of statistical physics》2019,175(6):1262-1297
Journal of Statistical Physics - Consider the free energy of a d-dimensional gas in canonical equilibrium under pairwise repulsive interaction and global confinement, in presence of a volume... 相似文献
66.
Leonard F. Lindoy George V. Meehan Ioana M. Vasilescu Hyun Jee Kim Ji-Eun Lee Shim Sung Lee 《Coordination chemistry reviews》2010,254(15-16):1713-1725
The transition and post-transition metal ion chemistry of a wide range of potentially pentadentate dibenzo-substituted macrocyclic ligands incorporating nitrogen, oxygen and/or sulfur donors is reviewed and shown to result in a diverse range of structural types. Aspects of metal ion recognition, bulk membrane transport, systems incorporating appended chromophores, a sulfate binding system, induced Cu(I)/Cu(II) redox switching, coordination polymers, and unsymmetric macrocyclic ligand systems are all discussed. 相似文献
67.
Spyros Drivelos Marilena E. Dasenaki Nikolaos S. Thomaidis 《Analytical and bioanalytical chemistry》2010,397(6):2199-2210
A new hydrophilic interaction liquid chromatographic (HILIC) method for the simultaneous determination of isoascorbic (IAA)
and ascorbic acid (AA) was developed. The separation of IAA and AA was studied in various HILIC stationary phases and the
influence of the composition of the mobile phase, the ionic strength and the column temperature to the chromatographic characteristics
is presented. The final method used an aminopropyl column under isocratic elution with acetonitrile–100 mM ammonium acetate
solution (90:10, v/v) at a flow rate of 0.4 mL/min and a detection wavelength of 240 nm. This method was validated and the calibration curves
were found to be linear in the range of 1.0–65 μg/mL for both IAA and AA. The method limit of detection for IAA determination
in fish tissue was 2.3 μg/g. Inter-day precision (as %RSDR) was ranged between 0.56% and 8.3% at three concentration levels, whereas the respected recoveries ranged between 82% and
98%. This method was applied to the determination of IAA (as additive E315) in frozen redfish samples. The hyphenation of
the HILIC separation with a tandem mass spectrometer was also studied and the problems encountered with negative electrospray
ionization under HILIC separation conditions are discussed. 相似文献
68.
Federica Bianchi Monica Mattarozzi Maria Careri Alessandro Mangia Marilena Musci Francesca Grasselli Simona Bussolati Giuseppina Basini 《Analytical and bioanalytical chemistry》2010,396(7):2639-2645
A simple and easily automable method based on solid-phase microextraction followed by gas chromatographic–mass spectrometric
analysis was developed for the determination of two potential angiogenesis modulators 17β-estradiol (17-BE) and 2-methoxyestradiol
(2-MEOE) in culture media. Trifluoroacetic anhydride was used as the derivatising agent. A homemade octadecyl silica coating,
characterised by a coating thickness of 72 ± 10 μm and a good thermal stability until 250 °C, was prepared. Experimental design
was used to optimise the extraction conditions in terms of derivatisation time, derivatisation temperature and time of extraction.
As for method validation, lower limits of quantification of 0.17 and 0.015 μg/l for 17β-estradiol and 2-methoxyestradiol,
respectively, were obtained. Finally, the capabilities of the developed fibres were evaluated for the analysis of the investigated
analytes developed by granulosa cells in culture media maintained under normoxic, hypoxic and anoxic conditions, in order
to better elucidate their possible role in the angiogenic process. An increase of the production of both 17-BE and 2-MEOE
in hypoxic and anoxic conditions seems to be related to the effect of oxygen deprivation. 相似文献
69.
Silvia Del Piero Andrea Melchior Davide Menotti Marilena Tolazzi Anders Døssing 《Journal of Thermal Analysis and Calorimetry》2009,97(3):845-851
An investigation on the thermodynamics of complex formation between Ag(I) ion and two tripodal ligands tris[(2-pyridyl)methyl]amine
(TPA) and 6,6′-bis-[bis-(2-pyridylmethyl)aminomethyl]-2,2′-bipyridine (BTPA) has been carried out in the aprotic solvents
dimethylsulfoxide (DMSO) and dimethylformamide (DMF) by means of potentiometry and titration calorimetry. The results for
TPA are compared with those already obtained for other aliphatic tripodal polyamines. In general, the TPA ligand forms complexes
less stable than 2,2′,2″-triaminotriethylamine (TREN) and tris(2-(methylamino)ethyl)amine (Me3TREN) as a result of the combination of higher structural rigidity of TPA and lower σ-donor ability of pyridinic moieties
with respect to primary and secondary amines. The same trend is found if the stability of Ag(I) complex with TPA is compared
with that of tris(2-(dimethylamino)ethyl)amine (ME6TREN), despite the pyridinic nitrogen is formally a tertiary one. Theoretical calculations run to explain the reasons of this
weaker interaction indicate that this difference is due to solvation, rather than to steric or σ-donor effects. The ligand
BTPA is able to form bimetallic species whose relative stability is largely influenced by the different solvation of Ag(I)
ion in DMSO and DMF rather than by the difference in the dielectric constants of these two media. 相似文献
70.
This paper studies the possibility to calculate efficiently compounds of real matrices which have a special form or structure.
The usefulness of such an effort lies in the fact that the computation of compound matrices, which is generally noneffective
due to its high complexity, is encountered in several applications. A new approach for computing the Singular Value Decompositions
(SVD’s) of the compounds of a matrix is proposed by establishing the equality (up to a permutation) between the compounds
of the SVD of a matrix and the SVD’s of the compounds of the matrix. The superiority of the new idea over the standard method
is demonstrated. Similar approaches with some limitations can be adopted for other matrix factorizations, too. Furthermore,
formulas for the n − 1 compounds of Hadamard matrices are derived, which dodge the strenuous computations of the respective numerous large determinants.
Finally, a combinatorial counting technique for finding the compounds of diagonal matrices is illustrated.
相似文献