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121.
Katya Besanon Gbor Laurenczy Tito Lumini Raymond Roulet Giuliana Gervasio 《Helvetica chimica acta》1993,76(8):2926-2935
The monosubstituted [Ir4(CO)11L] clusters (L = P(OPh)3, 1 ; L = P(OMe)3, 2 ; L = P(OCH2)3CEt, 3 ) were obtained in good yields by the reaction of [Ir4(CO)11 I ]? with the corresponding phosphite. In the solid state, cluster 3 has a Cs geometry with all terminal ligands as shown by an X-ray analysis. Three isomers are present in solution: one with terminal ligands ( A ) and two with three edge-bridging CO's and with L in axial ( B ) or radial ( C ) position (see Scheme). The thermodynamic and kinetic parameters of isomerisations B ? A and A ? C were determined by simulation of the variable-temperature 31P-NMR spectra. The three isomers correspond to three minima on the kinetic pathway of CO scrambling, whose relative energies vary independently within a small range (1–9 kJ mol?1 at 298 K). At low temperature, isomer C is always the least stable and is not observed for 1 which bears the most bulky phosphite ligand. The isomerisations are due to two intramolecular merry-go-rounds of CO groups about two unequivalent faces of the unbridged species A . 相似文献
122.
Through the insertion of a carbon dioxide molecule, the oxazolidin-2-ones () and () were prepared by treataent of the salts () and () with carbonate anion on polymeric support. The hydrolysis under basic conditions of () and () afforded the erythro-3-amino-1,2-diols () and () which were fully acetylated: the 2-amino-2-deoxyerythritol derivative () was obtained in 91% yield. 相似文献
123.
Pieri M Miraglia N Castiglia L Genovese G Basilicata P Simonelli A Acampora A 《Rapid communications in mass spectrometry : RCM》2005,19(21):3042-3050
Rapamycin is a potent immunosuppressive drug capable of significantly reducing acute graft rejection in kidney, liver and heart transplant patients. Its immunosuppressive activity and adverse effects have been related to rapamycin concentration, and therapeutic drug monitoring of the drug is deemed appropriate. This work was aimed at developing a new quantification method based on the isolation of the [M+Na]+ ion as precursor and its further fragmentation through an ion trap mass spectrometer equipped with an electrospray ionization source. A limit of detection (LOD) of 0.7 ng/mL was obtained, while the lower limit of quantification (LLOQ) was 2.4 ng/mL. The accuracy and reproducibility of the responses were evaluated and compared with results obtained when the [M+NH4]+ ion was chosen as the precursor in a triple quadrupole mass spectrometer. In this case the LOD was 0.5 ng/mL and the LLOQ 1.7 ng/mL. Data showed that it would be possible to use the quantification of the sodiated species for the routine determination of rapamycin, as an alternative to the commonly adopted method based on the ammoniated complex. 相似文献
124.
Giuliana Gervasio Domenica Marabello Enrico Sappa Andrea Secco 《Journal of Cluster Science》2008,19(1):63-71
The title complex is the main product of the reaction of Fe3(CO)12 with isopropenylacetylene in basic methanolic solution (followed by acidification); it is obtained upon carbon–carbon bond
forming and dimerization of the alkyne. The same complex is also obtained by reacting Fe3(CO)12 in CH3OH/KOH solution with 2-methyl-hex-1-en-3-yne; carbon–carbon bond cleavage presumably occurs to form isopropenylacetylene,
which then reacts with the iron carbonyl. The unprecedented structure of the complex has been determined with a X-ray diffraction
analysis.
相似文献
Andrea SeccoEmail: |
125.
Sonia Coriani Cristina Forzato Giada Furlan Patrizia Nitti Giuliana Pitacco Magnus Ringholm Kenneth Ruud 《Tetrahedron: Asymmetry》2009,20(13):1459-1467
The synthesis of a new, optically active, paraconic-acid derivative 4,4-dimethyl-5-oxo-tetrahydrofuran-3-carboxylic acid and its methyl and ethyl esters was accomplished by a procedure involving the kinetic enzymatic resolution of the racemic ethyl ester. Thus, ethyl (+)-4,4-dimethyl-5-oxo-tetrahydrofuran-3-carboxylate, derived from a ring fission, was isolated at low conversion values, with 94% ee using HLAP as the enzymatic source. The corresponding enantiomerically pure acid was also obtained.The absolute configuration of the products was determined based on the results of an extensive computational study of the specific rotation of the acid and methyl ester. Four different wavelengths were considered and comparisons with the sign and magnitude of the corresponding experimental observations were carried out. Solvent effects on both the conformational space and the specific rotation were included in the computations using the Polarizable Continuum Model.The assigned absolute configuration of the title compounds is (R)-(+), which is in agreement with a tentative experimental assignment based on an analysis of the circular dichroism curves. 相似文献
126.
Valeria Bugatti Giuliana Gorrasi Morena Nocchetti Vittoria Vittoria 《European Polymer Journal》2010,46(3):418-331
Intercalation compounds of ZnAl-Layered Double Hydroxide (LDH) with Benzoate (Bz), 2,4-dichlorobenzoate (BzDC), para-hydroxybenzoate (p-BzOH) and ortho-hydroxybenzoate (o-BzOH) anions, have been prepared via anion exchange procedure. The obtained inorganic-organic nano-hybrids were incorporated by High Energy Ball Milling (HEBM) into polycaprolactone (PCL), processed on laboratory scale and thin films were obtained. X-ray diffraction analyses of the samples indicated that both the nature and the position of the aromatic ring substituents affect the value of the interlayer distance and the hydrogen bonds of the nano-hybrids. Physical and barrier properties of water vapor were conducted on all the nanocomposite films, showing the influence of the exfoliation on the mechanical and barrier properties. A preliminary study on the release kinetic of the Bz anions bound to LDH was also performed, enlightening very good perspectives in the field of controlled release of active species. 相似文献
127.
Abnormalities in plasma von Willebrand factor (vWF) concentration and function result in von Willebrand disease (vWD). The diagnosis requires a battery of tests such as screening procedures, confirmatory tests, phenotypic characterization, and genotyping. The phenotypic testing (multimer pattern analysis) is important in order to subclassify the hereditary and the acquired forms of vWD. Only few laboratories are skilled to perform this analysis. The extreme range of protein size from 250 kDa monomer to over 20 000 kDa multimers requires a time‐consuming procedure (3–4 days) and presents many technical difficulties. To standardize the method and to overcome technical difficulties, we developed a rapid and sensitive semi‐automated method to visualize the multimeric structure of vWF. The semi‐automated method we present performs the electrophoresis of patient's plasma in 120 min on a precast gel. Gels are suitable for the G26 Interlab instrumentation. After gel blotting, the method allows visualization of the vWF multimer pattern directly on the membrane. We reduced the time required from 72 to 8 h and we propose this test for the first level screening of vWF multimer deficiency. 相似文献
128.
Federica Gobattoni Giuliana Lauro Roberto Monaco Raffaele Pelorosso 《Acta Appl Math》2013,125(1):173-192
In the present paper a review of some mathematical models for the ecological evaluation of environmental systems is considered. Moreover a new model, capable to furnish more detailed information at the level of landscape units, is proposed. Numerical tests are then performed for a case study in the province of Viterbo (central Italy). 相似文献
129.
Giuliana Righi Emanuela Mandic’ Gaia Clara Mercedes Naponiello Paolo Bovicelli Ilaria Tirotta 《Tetrahedron》2012,68(14):2984-2992
The results obtained from a study on the stereochemical control in the dihydroxylation of the double bond of vinyl epoxides and their derivatives (bromo derivatives, azido derivatives and vinyl aziridines) are presented herein. A significant diastereoselectivity was observed for the bromo derivatives, azido derivatives and N-protected vinyl aziridines, whereas vinyl epoxides and unprotected vinyl aziridines showed no diastereoselectivity. The results obtained are generally consistent with the Kishi model. 相似文献
130.
Home Care includes medical, paramedical and social services which are delivered to patients at their domicile rather than in hospital. Managing human and material resources in Home Care services is a difficult task, as the provider has to deal with peculiar constraints (e.g., the continuity of care, which imposes that a patient is always cared for by the same nurse) and to manage the high variability of patients’ demands. One of the main issues encountered in planning Home Care services under continuity of care requirement is the nurse-to-patient assignment. Despite the importance of this topic, the problem is only marginally addressed in the literature, where continuity of care is usually treated as a soft-constraint rather than as a hard one. Uncertainty is another relevant feature of nurse-to-patient assignment problem, and it is usually managed adopting stochastic programming or analytical policies. However, both these approaches proved to be limited, even if they improve the quality of the assignments upon those actually provided in practice. In this paper, we develop a cardinality-constrained robust assignment model, which allows exploiting the potentialities of a mathematical programming model without the necessity of generating scenarios. The developed model is tested on real-life instances related to a relevant Home Care provider operating in Italy, in order to evaluate its capability of reducing the costs related to nurses’ overtimes. 相似文献