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961.
In this paper, we examine the rheological and the structural properties of different types of gelatin networks, physical, chemical and both. The physical gel is due to the formation of collagen type triple helices when cooling the solutions. Chemically crosslinked gels are obtained with a reagent, in our case the bis(vinylsulfonyl)methane (BVSM), kindly provided by Kodak Industrie (France). Each BVSM molecule provides two covalent bonds. The chemical reaction was followed by microcalorimetry (MicroDSC III from Setaram, Caluire, France). The relation between shear moduli and crosslinking for the three types of gels is discussed, in relation with theoretical models of randomly crosslinked systems. 相似文献
962.
Zo Andriamialisoa Alain Valla Dominique Cartier Roger Labia 《Helvetica chimica acta》2002,85(9):2926-2929
A new synthesis of acitretin via a C15+C5 route is reported. The C15 unit is the key step, involving a procedure that provides the required (all‐E)‐C15‐aldehyde with high stereoselectivity. 相似文献
963.
Dehay Dominique El Waled Khalil Monsan Vincent 《Statistical Inference for Stochastic Processes》2021,24(1):17-33
Statistical Inference for Stochastic Processes - This paper deals with the parametric inference for integrated continuous time signals embedded in an additive Gaussian noise and observed at... 相似文献
964.
Andrea Preuß Sebastian Notz Eduard Kovalski Dr. Marcus Korb Dr. Thomas Blaudeck Dr. Xiao Hu Dr. Jörg Schuster Dr. Dominique Miesel Dr. Tobias Rüffer Dr. Alexander Hildebrandt Dr. Katja Schreiter Prof. Dr. Stefan Spange Prof. Dr. Stefan E. Schulz Prof. Dr. Heinrich Lang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2635-2652
The synthesis of 1-Fc- ( 3 ), 1-Br-6-Fc- ( 5 a ), 2-Br-7-Fc- ( 7 a ), 1,6-Fc2- ( 5 b ), 2,7-Fc2-pyrene ( 7 b ), 3,6-Fc2-9,10-phenanthrenedione ( 10 ), and 3,6-Fc2-9,10-dimethoxyphenanthrene ( 12 ; Fc=Fe(η5-C5H4)(η5-C5H5)) is discussed. Of these compounds, 10 and 12 form 1D or 2D coordination polymers in the solid state. (Spectro)Electrochemical studies confirmed reversible Fc/Fc+ redox events between −130 and 160 mV. 1,6- and 2,7-Substitution in 5 a (E°′=−130 mV) and 7 a (E°′=50 mV) influences the redox potentials, whereas the ones of 5 b and 7 b (E°′=20 mV) are independent. Compounds 5 b , 7 b , 10 , and 12 show single Fc oxidation processes with redox splittings between 70 and 100 mV. UV/Vis/NIR spectroelectrochemistry confirmed a weak electron transfer between FeII/FeIII in mixed-valent [ 5 b ]+ and [ 12 ]+. DFT calculations showed that 5 b non-covalently interacts with the single-walled carbon nanotube (SWCNT) sidewalls as proven by, for example, disentangling experiments. In addition, CV studies of the as-obtained dispersions confirmed exohedral attachment of 5 b at the SWCNTs. 相似文献
965.
Lydie Harmand Marie-Hélène Lescure Nicolas Candelon Mathieu Duttine Dominique Lastécouères Jean-Marc Vincent 《Tetrahedron letters》2012,53(11):1417-1420
The copper(II) complex [Cu(C186tren)](Br)2, 2, is an efficient precatalyst for the Huisgen ‘click’ cycloaddtion which can be used at low loading without the requirement of an external sacrificial reductant such as sodium ascorbate. EPR studies support the in situ reduction of 2 by the alkyne to generate a reactive copper(I) catalyst. 相似文献
966.
Dr. Matthieu Autillo Laetitia Guerin Dr. Thomas Dumas Dr. Mikhail S. Grigoriev Dr. Alexandre M. Fedoseev Sebastiano Cammelli Pier Lorenzo Solari Dr. Dominique Guillaumont Dr. Philippe Guilbaud Dr. Philippe Moisy Dr. Hélène Bolvin Dr. Claude Berthon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(17):4435-4451
The magnetic properties of LnIII and AnIII complexes formed with dipicolinate ligands have been studied by NMR spectroscopy. To know precisely the geometries of these complexes, a crystallographic study by single-crystal X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) in solution was performed. Several methods to separate the paramagnetic shifts observed in the NMR spectra were applied to these complexes. Methods using a number of nuclei of the dipicolinate ligands revealed an abrupt change in the geometries of the complexes and a metal–ligand interaction in the middle of the lanthanide series. A study of the variation of the paramagnetic shifts with temperature demonstrated that higher-order terms of the dipolar and contact contributions are required, especially for the lightest LnIII and almost all the studied AnIII. Bleaney's parameters <Sz>a and relating to the contact and dipolar terms, respectively, were deduced from experimental data and compared with the results of ab initio calculations. Quite a good agreement was found for the temperature dependencies of <Sz>a and . However, the values obtained from cation magnetic anisotropy calculations showed some discrepancies with the values derived from Bleaney's equation defined for LnIII. Other parameters, such as the crystal field parameter and the hyperfine constants Fi obtained from the experimental data of the [An(ethyl-dpa)3]3− complexes (ethyl-dpa=4-ethyl-2,6-dipicolinic acid), are at odds with the assumptions underlying Bleaney's theory. 相似文献
967.
Abouelmagd Abdelsamie Dominique Thévenin 《Proceedings of the Combustion Institute》2019,37(3):3373-3382
Detailed investigations of turbulent spray combustion are very challenging due to the complexity of the underlying physicochemical processes. Experimentally, laboratory-scale burners are increasingly used to investigate these processes and support model development. One ultimate objective of these studies would be to deliver suitable benchmark data. In the present paper, the focus is similar but relying exclusively on direct numerical simulations. Conditions close that found in lab-scale burners are considered in the simulations, so that direct comparisons will ultimately become possible. The current analysis concentrates on the temporal evolution of temperature and concentrations of OH, CH2O, and CH4. The profiles of these variables show very complex features, therefore separate zones corresponding to characteristic physicochemical regimes have been tracked in time and space. It is found that, based on the temperature profile, four different zones coexist in the domain, associated to different degrees of competition between evaporation and reaction. It is observed that high concentrations of CH2O and CH4 can be used to delineate between three characteristic locations: 1) the evaporation zone; 2) close to the jet tip, at high temperatures; and 3) regions where evaporated droplets are entrained by mixing. This study demonstrates that direct numerical simulation of small spray burners can be used to deliver important information and to contribute useful benchmark data. 相似文献
968.
Reinterpretation of Dynamic Vibrational Spectroscopy to Determine the Molecular Structure and Dynamics of Ferrocene 下载免费PDF全文
Dr. Stephen P. Best Prof. Feng Wang M. Tauhidul Islam Shawkat Islam Dr. Dominique Appadoo Ryan M. Trevorah Prof. Christopher T. Chantler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(50):18019-18026
Molecular distortion of dynamic molecules gives a clear signature in the vibrational spectra, which can be modeled to give estimates of the energy barrier and the sensitivity of the frequencies of the vibrational modes to the reaction coordinate. The reaction coordinate method (RCM) utilizes ab initio‐calculated spectra of the molecule in its ground and transition states together with their relative energies to predict the temperature dependence of the vibrational spectra. DFT‐calculated spectra of the eclipsed (D5h) and staggered (D5d) forms of ferrocene (Fc), and its deuterated analogue, within RCM explain the IR spectra of Fc in gas (350 K), solution (300 K), solid solution (7–300 K), and solid (7–300 K) states. In each case the D5h rotamer is lowest in energy but with the barrier to interconversion between rotamers higher for solution‐phase samples (ca. 6 kJ mol?1) than for the gas‐phase species (1–3 kJ mol?1). The generality of the approach is demonstrated with application to tricarbonyl(η4‐norbornadiene)iron(0), Fe(NBD)(CO)3. The temperature‐dependent coalescence of the ν(CO) bands of Fe(NBD)(CO)3 is well explained by the RCM without recourse to NMR‐like rapid exchange. The RCM establishes a clear link between the calculated ground and transition states of dynamic molecules and the temperature‐dependence of their vibrational spectra. 相似文献
969.
Sanae Abrakhi Sébastien Péralta Sophie Cantin Odile Fichet Dominique Teyssié 《Colloid and polymer science》2012,290(5):423-434
The photochemical behavior of photosensitive materials obtained by spin-coating or network synthesis of a cellulosic polymer
bearing photo-cross-linkable cinnamate groups was investigated. First, cinnamate groups were grafted on a cellulose acetate
butyrate polymer, with different grafting densities. The photochemical properties of the polymers were studied in solution
by UV–visible and 1H NMR spectroscopy. Then spin-coated films and networks were prepared and characterized as a function of the number of cinnamate
groups per cellulosic unit. The water-wetting properties of both surfaces were studied by dynamic contact angle measurements,
before and after photoirradiation, and subsequent heating. The surfaces obtained by the two methods have significantly different
behaviors that can be assigned to the distinct photochemical pathways of the cinnamate groups upon irradiation depending on
the sample preparation. Indeed, dimerization reaction is evidenced as the main process in the spin-coated films while the
expected isomerization is predominant at the surface of the polymer networks. 相似文献
970.
The reaction of [MnII(S-mandelato)2] complexes with 5-Methyl-salicylaldoxim (5-Me-saloxH2) leads to the chiral hexanuclear manganese(III) complex [Mn6(μ3-O)2(5-Me-salox)6(S-mandelato)2(EtOH)6]. The structure can be viewed as two neutral stacked {Mn3(μ3-O)(5-Me-salox)3(S-mandelato)(EtOH)3} triangular subunits linked together in a head-to-tail manner by two phenoxo and two oximato μ3-oxygen atoms of the deprotonated oxime groups of the ligands. The magnetic study of this chiral hexanuclear manganese(III) complex reveals a SMM behaviour with an energy barrier of the slow relaxation of the magnetisation equal to 35 K. Considering the structural features, the fitting of the temperature dependence of the magnetic susceptibility gives a good agreement with the experimental data considering two sets of interactions: J1 = +0.37 cm−1 and J2 = −0.70 cm−1 within (ferromagnetic) and between (antiferromagnetic), respectively, the {Mn3(μ3-O)(5-Me-salox)3(S-mandelato)(EtOH)3} triangular subunits. 相似文献