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71.
Dr. Anthony D'Aléo Dr. David Gachet Dr. Vasile Heresanu Dr. Michel Giorgi Prof. Frédéric Fages 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(40):12764-12772
This article describes a series of nine complexes of boron difluoride with 2′‐hydroxychacone derivatives. These dyes were synthesized very simply and exhibited intense NIR emission in the solid state. Complexation with boron was shown to impart very strong donor–acceptor character into the excited state of these dyes, which further shifted their emission towards the NIR region (up to 855 nm for dye 5 b , which contained the strongly donating triphenylamine group). Strikingly, these optical features were obtained for crystalline solids, which are characterized by high molecular order and tight packing, two features that are conventionally believed to be detrimental to luminescence in organic crystals. Remarkably, the emission of light from the π‐stacked molecules did not occur at the expense of the emission quantum yield. Indeed, in the case of pyrene‐containing dye 4 , for example, a fluorescence quantum yield of about 15 % with a fluorescence emission maximum at 755 nm were obtained in the solid state. Moreover, dye 3 a and acetonaphthone‐based compounds 1 b , 2 b , and 3 b showed no evidence of degradation as solutions in CH2Cl2 that contained EtOH. In particular, solutions of brightly fluorescent compound 3 a (brightness: ε×Φf=45 000 M ?1 cm?1) could be stored for long periods without any detectable changes in its optical properties. All together, these new dyes possess a set of very interesting properties that make them promising solid‐state NIR fluorophores for applications in materials science. 相似文献
72.
Permanent binary phase masks with planar surfaces and high tolerance to laser radiation are recorded in the volume of photo-thermo-refractive glass using the contact copying technique and binary amplitude master masks. Conversion of a Gaussian beam to higher order modes is shown. 相似文献
73.
74.
Marin Borcut Vasile Berinde 《Applied mathematics and computation》2012,218(10):5929-5936
In this paper we introduce the concept of a tripled coincidence point for a pair of nonlinear contractive mappings F : X3 → X and g : X → X. The obtained results extend recent coincidence theorems due to ?iri? and Lakshmikantham [V. Lakshmikantham, L. ?iri?, L., Coupled fixed point theorems for nonlinear contractions in partially ordered metric spaces, Nonlinear Anal. 70 (2009) 4341-4349]. 相似文献
75.
In this paper we establish some optimality and duality results under generalized convexity assumptions for a multiobjective programming problem involving generalized d-type-I and related n-set functions. 相似文献
76.
Raluca Nicoleta Darie Mihai Brebu Cornelia Vasile Marek Kozlowski 《Polymer Degradation and Stability》2003,80(3):551-566
Binary isotactic polypropylene (IPP)/polyamide 6 (PA6) and ternary IPP/PA6/ethylene–propylene diene terpolymer (EPDM) blends in various ratios were obtained in a Haake Rheocord mixer. Processing behaviour was changed in the presence of IPP functionalized with bismaleimide (BMI), maleic anhydride (MA) and acrylic acid (AA) as reactive compatibilizing agents. The thermal and thermo-oxidative behaviour of blends was studied by differential scanning calorimetry and thermogravimetry. The functionalized IPPs modify the crystallinity degree and the decomposition behaviour of both IPP and PA6 as a result of chemical reactions of functional groups with those of the PA6. The changes depend on the IPP/PA6 or IPP/PA6/EPDM ratio, the chemical nature and amount of the functionalized IPP. On the basis of the processing and thermal data one can conclude that the compatibilizing agent effect increases in the following order: IPP-AA 相似文献
77.
Mihaela Deaconu Ioana Nicu Robert Tincu Ana-Maria Brezoiu Raul-Augustin Mitran Eugeniu Vasile Cristian Matei Daniela Berger 《Chemical Papers》2018,72(8):1869-1880
Doxycycline, an antibiotic from the tetracycline class with a broad spectrum of activity, was used to prepare drug delivery systems based on pristine and functionalized mesostructured silica supports. MCM-41-type materials with different textural, structural, and surface properties were used to assess their influence on the drug release kinetics. Small- and wide-angle XRD, FTIR spectroscopy and N2 adsorption/desorption isotherms were used to characterize the carriers before and after doxycycline loading. The drug release experiments were performed in vitro in 0.2 M phosphate buffer solution at 37 °C, and the slowest drug release kinetics was obtained for magnesium-modified MCM-41 carrier. All drug-loaded materials exhibited good antibacterial activity against Klebsiella pneumoniae ATCC 10031 strain, similar to the drug alone. 相似文献
78.
Thermoxidative Decomposition of Some Polysulfones under Dynamic Conditions of Heating 总被引:1,自引:0,他引:1
Vasile Cornelia Costea Elena Pascu Mihaela C. Warshawsky A. 《Journal of Thermal Analysis and Calorimetry》1998,52(2):569-579
Kinetic aspects of the first step of thermoxidative decomposition, under dynamic conditions of heating, of some polysulfones
have been studied.
The dependence of the kinetic parameters on the heating rate and conversion degree has been established. The compensation
effect and conversion function have also been discussed.
Polysulfone decomposes by the breaking of the main chain, a process involving very high activation energy.
Chemically modified polysulfones show the first step of thermoxidative decomposition at relatively low temperatures. This
step corresponds to the elimination of functional side - groups for the bromomethylated polysulfone while in the case of the
carboxylated polysolfone, the loss of the carboxyl group is probably accompanied by a crosslinking reaction.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
79.
The time dependence of the microscopical aspect, crystallinity, viscosity of the spinning solutions and the thermal and tinctorial properties of films formed from binary, ternary copolymers and binary copolymer mixtures of acrylonitrile with vinyl acetate and χ-methylstyrene have been compared. The characteristics of binary copolymers and incompatible mixtures are stable with time, while those of ternary copolymers and pseudocompatible mixtures evolve towards a limiting state. with phase separation. 相似文献
80.
Polysulfone udel was chemically functionalized with chloromethylene functional groups via the chloromethylation reaction. A new azomethine dimesogen containing one phenolic hydroxyl functional group was recently synthesized and proved to exhibit a large nematic mesophase range in the liquid state. Further reaction of the dimesogen with the functionalized polysulfone using a transquaternization reaction led to new polysulfones bearing pendant rigid dimesogenic units--no spacer being involved in the chemical design of the polymer. The polymers were characterized by IR, 1H NMR spectroscopy techniques, and their thermotropic liquid crystallinity behaviour was studied by optical polarizing microscopy (PLM) and DSC measurements. Enantiotropic nematic mesophases were observed under the PLM. A dependence of the melting temperature on the degree of substitution was noticed. 相似文献