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91.
Giuseppina Castronuovo Marcella Niccoli 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(3-4):289-294
The formation of complexes between methyl-α-cyclodextrin (MαCD) and monocarboxylic acids from C5 to C12 or cycloalkanols has been studied calorimetrically at 298 K in aqueous phosphate buffer, pH 11.3. The forces involved in
the association process are discussed according to the signs and values of the thermodynamic parameters obtained: association
enthalpy, constant, Gibbs energy and entropy.
Methyl-α-cyclodextrin forms 1:1 inclusion complexes with monocarboxylic acids, characterized by a monotonous increase in the
values of enthalpies and association constants at increasing alkyl chain length. Association is characterized by negative
enthalpies and by positive entropies: that determines large association constants. That behaviour is compared to the unusual
trend in the values of the association constants shown by the parent α-cyclodextrin interacting␣with the same monocarboxylic
acids. The model proposed to rationalize the present data provides a cavity elongation effect. Namely, because of the presence
of the methyl groups on the outside, the cavity behaves as it were deeper than that of the parent cyclodextrin.
The association with cycloalkanols—cyclohexanol, cycloheptanol, cyclooctanol and 1-cylohexyl-ethanol—is characterized by lower
entropies, as determined by the␣enhanced negative contribution originating from the␣tighter fit of the guest into the cavity. 相似文献
92.
93.
Barbara Cardinali Gianluigi Lunardi Enrico Millo Andrea Armirotti Gianluca Damonte Aldo Profumo Stefania Gori Giuseppina Iacono Alessia Levaggi Lucia Del Mastro 《Analytical and bioanalytical chemistry》2014,406(18):4557-4561
Trastuzumab, a humanized monoclonal antibody directed against the epidermal growth factor receptor 2 (HER2), is a milestone in the treatment of HER2-overexpressing breast cancer patients. An enzyme-linked immunosorbent assay (ELISA) for trastuzumab has been developed for routine use in the laboratory to support clinical and pharmacokinetic studies to optimize therapy. The method relies on an antigen peptide linked to a 96-well plate via the streptavidin/biotin system. The peptide sequence mimics the extracellular portion of the HER2 receptor that is recognized by trastuzumab. The calibration range of the assay is 10 to 360 ng/mL per well, corresponding to a trastuzumab serum concentration from 5 to 180 μg/mL with a lower limit of quantification of 10 μg/mL. Validation results demonstrate that trastuzumab can be accurately and precisely quantified in human serum using this assay. The procedure was also tested in sera obtained from breast cancer patients to evaluate trastuzumab serum levels, confirming the applicability of method that could be a valid assay to use in daily laboratory practice. 相似文献
94.
Regularity results and critical group estimates are studied for critical (p, r)-systems. Multiplicity results of solutions for a critical potential quasilinear system are also proved using Morse theory. 相似文献
95.
Ortensia Ilaria Parisi Francesco Puoci Francesca Iemma Giuseppina De Luca Manuela Curcio Giuseppe Cirillo Umile Gianfranco Spizzirri Nevio Picci 《先进技术聚合物》2010,21(11):774-779
A novel, simple synthetic strategy for the preparation of crosslinked polymers with significant antioxidant properties is proposed. Ferulic acid (FA), a well‐known antioxidant compound, due to its reactivity toward free radical process, was inserted into a polymeric network with methacrylic acid (MAA) and ethylene glycole dimethacrylate acting as comonomer and crosslinker, respectively. All the reactants were simultaneously mixed in the polymerization feed and one‐pot radical reaction was carried out. Irregular microparticles were prepared by bulk polymerization and microspheres by precipitation polymerization. The materials were characterized by nuclear magnetic resonance–magic angle spinning (NMR‐MAS) studies, to verify effective FA insertion into polymeric networks, and by morphological, dimensional analyses, and water absorption measurement to study their superficial and swelling properties, respectively. Antioxidant properties of materials were evaluated by linoleic acid emulsion system–thiocyanate assay, determination of scavenging activity on DPPH radicals, determination of available phenolic groups in polymeric matrices, and determination of total antioxidant capacity. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
96.
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
97.
98.
Fractional wavelet transform (FWT) was applied to the original absorption spectra of lacidipine (LAC) and its photodegradation product (LACD), and the resulting FWT spectra were processed by continuous wavelet transform (CWT) and multilinear regression calibration (MLRC) for the simultaneous quantitative analysis of both products in their binary mixtures. These methods do not require any chemical separation step and chemical complex reaction to obtain a detectable signal for the degradation product. By using the Mexican hat function, 2 calibration functions for LAC and LACD were obtained by measuring the CWT transformed signals at 416.1 nm for LAC and 414.6 nm for LACD, after FWT processing of the original absorption spectra. The calibration graphs were linear in the concentration range of 5.08-40.64 microg/mL for LAC and 0.51-8.16 microg/mL for LACD. The limit of detection and the limit of quantitation were found to be 0.289 and 0.956 microg/mL for LAC and 0.036 and 0.118 microg/mL for LACD, respectively. For comparison, the MLRC algorithm was applied to the linear regression functions for the individual drug and its photoproduct. In this approach, a set of linear regression functions was obtained from the relationship between concentrations and FWT signals in the wavelength range 411.0-412.4 nm. Both methods were applied to the quantitative evaluation of LAC and LACD in laboratory and pharmaceutical samples, and produced very satisfactory results. 相似文献
99.
Kirchhoff systems with dynamic boundary conditions 总被引:2,自引:0,他引:2
Giuseppina Autuori 《Nonlinear Analysis: Theory, Methods & Applications》2010,73(7):1952-1965
We are interested in the study of the global non-existence of solutions of hyperbolic nonlinear problems, governed by the p-Kirchhoff operator, under dynamic boundary conditions, when p>pn with pn<2. The systems involve nonlinear external forces and may be affected by a perturbation of the type |u|p−2u. Several models already treated in the literature are covered in special subcases, and concrete examples are provided for the source term f and the external nonlinear boundary damping Q. 相似文献
100.