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361.
In many recent publications, supposed athermal effects of water-filtered infrared A (wIRA) irradiation are discussed. Those effects are mainly attributed to wavelengths in the range from 780 to 1440 nm, and should not result from warming of cellular water or any aqueous medium surrounding the irradiated sample caused by wIRA absorption. Athermal effects are considered to be induced directly by absorption of different wavelengths of the wIRA spectrum by cellular molecules or structures except water. To distinguish between thermal and athermal effects, irradiated samples have to be subjected to a very effective and precise temperature homeostasis. Any experimental effects can only be attributed to pure athermal effects, if the temperature of the irradiated samples is verifiably constant and does not result in hyperthermia. Here, data of temperature distribution in Petri dishes of different types filled with aqueous medium are presented which were estimated by model calculation for different setups of cooling. Additionally, the real temperature development was directly measured. Such a cooling unit enables long-term application of high wIRA irradiances and large doses without any detectable warming of the irradiated samples, in single cell layers. Using such a setup, thermal and athermal effects can be compared and in addition to that quantified. 相似文献
362.
Walther B Lorén N Nydén M Hermansson AM 《Langmuir : the ACS journal of surfaces and colloids》2006,22(19):8221-8228
The influence of the microstructures of different kappa-carrageenan gels on the self-diffusion behavior of poly(ethylene glycol) (PEG) has been determined by nuclear magnetic resonance (NMR) diffusometry and transmission electron microscopy (TEM). It was found that the diffusion behavior was determined mainly by the void size, which in turn was defined by the state of aggregation of the kappa-carrageenan. The kappa-carrageenan concentration was held constant at 1 w/w%, and the aggregation was controlled by the amount of potassium and/or sodium chloride and, for samples containing potassium, also by the cooling rate. Gels containing potassium formed microstructures where kappa-carrageenan strands are rather evenly distributed over the image size, while sodium gels formed dense biopolymer clusters interspersed with large openings. In a gel with small void sizes, relatively slow diffusion was found for all PEG sizes investigated. Extended studies of the self-diffusion behavior of the 634 g mol(-)(1) PEG showed that there is a strong time dependence in the measured PEG diffusion. An asymptotic lower time limit of the diffusion coefficient was found in all gels when the diffusion observation time was increased. According to the ratio, D/D(0), where D(0) is the diffusion coefficient in D(2)O and D is the diffusion coefficient in the gels, the gels could be divided into three classes: small, medium, and large voids. For quenched kappa-carrageenan solutions with salt concentrations of 20 mM K(+), 100 mM K(+), or 20 mM K(+)/200 mM Na(+) as well as slowly cooled solutions with only 20 mM K(+), D/D(0) ratios between 0.18 and 0.29 were obtained. By quenching a kappa-carrageenan solution with 100 mM K(+), the D/D(0) was 0.5, while D/D(0) ratios between 0.9 and 1 were obtained in a quenched solution with 250 mM Na(+) and slowly cooled samples with 20 mM K(+)/200 mM Na(+) or 250 mM Na(+). 相似文献
363.
364.
Ouali A Laurent R Caminade AM Majoral JP Taillefer M 《Journal of the American Chemical Society》2006,128(50):15990-15991
Imino pyridine-capped phosphorus dendrimers were found to strongly enhance the catalytic activity of copper in arylations and vinylations of O- and N-nucleophiles. These reactions could indeed be performed under very mild conditions, often the mildest to date. Interestingly, such performances could not be obtained when using the monomeric imino pyridine chelating ligand alone. To the best of our knowledge, this constitutes a rare example of such a positive dendritic effect in the field of organometallic catalysis. 相似文献
365.
Cp(2)MoS(4), 1, in CH(2)Cl(2) undergoes extensive oxidation by m-CPBA at -78 degrees C to give a 1,1,4,4-tetroxide, 2 (59%). Tetraoxide 2 rearranges at room temperature to give an unusual sulfur-atom protonated molybdocene disulfide dimer [(Cp(2)MoS(2)H)(2)](HSO(4))(2), 3. Crystal data for 3 are P, a = 6.751(2) Angstroms, b = 9.865(4) Angstroms, c = 11.549(5) Angstroms, alpha = 109.95(3) degrees, beta = 96.11(3) degrees, gamma = 108.22(3) degrees, V = 666.9(4) Angstroms(3), and Z = 1. The dimer was also obtained directly when the oxidation was conducted at 0 degree C in DMF. Under basic conditions, the dimer is cleaved to give molybdocene disulfide Cp(2)MoS(2), while treatment of the latter with acid converts it to the dimer 3. 相似文献
366.
Erik Geissler Anne-Marie Hecht Cyrille Rochas Ferenc Horkay Peter J. Basser 《Macromolecular Symposia》2005,227(1):27-38
This paper gives two examples of experiments that demonstrate the power of small angle scattering techniques in the study of swollen polymer networks. First, it is shown how the partly ergodic character of these systems is directly detected by neutron spin echo experiments. The observed total field correlation function of the intensity scattered from a neutral gel allows the ergodic contribution to be directly distinguished from the non ergodic part, at values of transfer wave vector q that lie well beyond the range of dynamic light scattering. The results can be compared with those obtained at much lower q from visible light scattering. Second, a recent application of small angle X-ray (SAXS) and neutron (SANS) scattering is described for a polyelectrolyte molecule, DNA, in semi-dilute solutions under near-physiological conditions. For these observations, the divalent ion normally present, calcium, is replaced by an equivalent ion, strontium. The comparison between SANS and SAXS yields a quantitative picture of the cloud of divalent counter-ions around the central DNA core. At physiological conditions, the cloud is thinner than that predicted on the basis of the Debye screening length but thicker than if the counter-ions were condensed on the DNA chain. 相似文献
367.
Robert Deschenaux Florence Monnet Elisabeth Serrano Franois Turpin Anne-Marie Levelut 《Helvetica chimica acta》1998,81(11):2072-2077
The synthesis and liquid-crystalline properties of tetracatenar covalent and H-bonded bis-ferrocene derivatives 1 and 2 , respectively, are reported. Both compounds gave rise to enantiotropic columnar liquid-crystalline behavior with a hexagonal molecular organization. To explore the possibility to obtain also calamitic liquid-crystalline phases from H-bonded ferrocene-containing liquid crystals, a rod-shaped ferrocene mesogen 3 was synthesized, which gave rise to enantiotropic smectic C and smectic A phases. For the first time, a rational synthetic design at the ferrocene level led to ferrocene-based liquid-crystals with columnar behavior and to H-bonded metallomesogens. 相似文献
368.
Julien Sayettat Lucy M. Bull Jean-Christophe P. Gabriel Stphane Jobic Franck Camerel Anne-Marie Marie Marc Fourmigu Patrick Batail Raymond Brec Ren-Louis Inglebert 《Angewandte Chemie (International ed. in English)》1998,37(12):1711-1714
A remarkable autofragmentation/rearrangement sequence results in the unprecedented formation of inorganic concave cyclic anion [(NiPS4)3]3− (structure shown on the right) upon dissolving the potassium salt of the charged mineral polymer 1∞[NiPS4]− in DMF; the initial complex fluid has a transient anisotropic texture that can be identified by optical microscopy under polarized light. In contrast, the complex fluid that results upon dissolving 1∞[PdPS4]− is stable up to 323 K as persistent, flexible, charged chains. 相似文献
369.
Ferenc Horkay Mikls Zrinyi Erik Geissler Anne-Marie Hecht 《Macromolecular Symposia》1990,40(1):195-202
The dependence of the shear modulus and of the swelling equilibrium concentration of polyvinylacetate gel homologues in equilibrium with excess isopropyl alcohol is investigated in the temperature range 30≤T≤70°C. At the theta temperature (T=52°C) the volume elastic modulus was also determined and compared with the shear modulus. The results are interpreted in terms of a free-energy function derived on the basis of the network unfolding hypothesis. 相似文献
370.
Anne-Marie Caminade Aurélien Hameau Kathleen Moineau-Chane Ching Cédric-Olivier Turrin 《Helvetica chimica acta》2023,106(7):e202300048
This review presents the synthesis of dendrons (dendritic wedges) based on cyclotriphosphazene cores, in which one function is a fluorescent group, and the five remaining functions are used for growing the dendritic branches. The growing of the branches is carried out by a divergent method, using a two-step process which implies hydroxybenzaldehyde and the phosphorhydrazide H2NNMeP(S)Cl2. Four different fluorophores have been used, derived from maleimide, julolidine, pyrene, or from a near-infra-red fluorophore. Depending on the type of fluorophore and on the type of terminal functions of the dendrons, different applications have been targeted. One can cite experiments in catalysis or for the elaboration of materials, transfection experiments, the study of anti-cancer properties, and imaging in relation with the human immune system. 相似文献