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261.
Mohesh Moothanchery Izabela Naydenova Vincent Toal 《Applied Physics A: Materials Science & Processing》2011,104(3):899-902
We studied the shrinkage in acrylamide-based photopolymer by measuring the Bragg detuning of transmission diffraction gratings
recorded at different slant angles and at different intensities. Transmission diffraction gratings of spatial frequency 1000
lines/mm were recorded in an acrylamide-based photopolymer film having 60±5 μm thickness. We have obtained the grating thickness
and the final slant angles from the Bragg curve and hence calculated the shrinkage caused by holographic recording. The shrinkage
of the material was evaluated for three different recording intensities 1, 5 and 10 mW/cm2, while the total exposure energy was kept constant at 80 mJ/cm2. From the experimental results it can be seen that the shrinkage of the material is higher for recording with lower intensities
and the corresponding values are 1.9%, 1.3% and 1%. 相似文献
262.
Izabela Tworowska Wojciech Dabkowski Jan Michalski 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1855-1858
Oligonucleotides containing 3'- S -P(S) and 5'- S -P(S) fragments in the deoxy-series are available only by tedious multistep procedures. We have developed a novel and efficient methodology based on ring opening of anhydronucleosides by phosphorus dithioacids. This approach allows efficient synthesis of modified dinucleotides of the ribo-series. 相似文献
263.
Izabela Petrykiewicz 《Comptes Rendus Mathematique》2014,352(4):273-276
The aim of this note is to present results concerning the differentiability of some Fourier series arising from Eisenstein series. Sine series exhibit different behaviours with respect to differentiability than the series with cosine function. The precise results are given for the series related to Eisenstein series of weight 2, whereas for the series arising from Eisenstein series of higher weight we conjecture the results. 相似文献
264.
A practical modification of the Gassman 3-(methylthio)oxindole synthesis is reported. In our method, substituted anilines and 2-(methylthio)acetamide were reacted under mild reaction conditions, in the presence of N-chlorophthalimide as a chlorinating agent to give α-amidosulfides, which, in the next step of the process, were cyclized to give 3-(methylthio)oxindoles. The method was successfully applied for the synthesis of the key intermediate, 2-(2-amino-3-benzoylphenyl)-2-(methylthio)acetamide, in the process of the preparation of nepafenac, a commonly used ophthalmic drug. 相似文献
265.
The Virtue of Defects: Stable Bromine Production by Catalytic Oxidation of Hydrogen Bromide on Titanium Oxide 下载免费PDF全文
Maximilian Moser Dr. Izabela Czekaj Prof. Núria López Prof. Javier Pérez‐Ramírez 《Angewandte Chemie (International ed. in English)》2014,53(33):8628-8633
Rutile TiO2 is a heavily investigated oxide with, to date, scarce applications in industrial catalysis. The inactivity of this material in oxidations has been related to its inability to dissociate molecular oxygen. Herein we show how rutile catalyzes the oxidation of HBr to Br2 through defect states that are introduced during the reaction. The identification of active, stable, and abundant materials for bromine production is key to the future implementation of Br2‐mediated alkane functionalization processes. The catalytic properties of TiO2 are discussed in comparison to expensive rutile‐type oxides, such as RuO2 and IrO2, on the basis of surface characterization and molecular modeling. 相似文献
266.
Several polychlorinated biphenyls (PCBs) and their hydroxylated metabolites display axial chirality. Here we describe an enantioselective, gas chromatographic separation of methylated derivatives of hydroxylated (OH-)PCB atropisomers (MeO-PCB) using a chemically bonded beta-cyclodextrin column (Chirasil-Dex). The atropisomers of several MeO-PCBs could be separated on this column with resolutions ranging from 0.42 to 0.87 under isothermal or temperature-programmed conditions. In addition, the enantiomeric fraction of OH-PCB 136 metabolites was determined in male and female rats treated with racemic PCB 136. The methylated derivatives of two OH-PCB 136 metabolites showed an enantiomeric enrichment in liver tissue, whereas PCB 136 itself was near racemic. 相似文献
267.
Kruczała K Szczubiałka K Łańcucki Ł Zastawny I Góra-Marek K Dyrek K Sojka Z 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(5):1337-1343
The research was focused on synthesis of proton conductive, easily degradable polymer membranes, which can be used as a model system to verify the efficiency of transition metal ions (TMI) in prevention of polymer degradation. Two polymers composed of 2-hydroxyethyl methacrylate (HEMA), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS), and styrenesulfonic acid (SS) were synthesized. The copolymers were characterized by gel permeation chromatography (GPC), elementary analysis, and FTIR and fluorescence spectroscopies. The results allowed determination of weight-average molecular weight and the copolymer composition. The protons of sulfonic groups were substituted by paramagnetic transition metal ions of various spin states (Cr(3+), S=3/2 and Mn(2+), S=5/2) with the loading varying from 0.5 up to 10 mol%. The effectiveness of spin catalysis was checked by EPR. The results obtained indicate enhancement of polymer stability in the presence of Mn(2+). 相似文献
268.
Kossakowski J Bielenica A Mirosław B Kozioł AE Dybała I Struga M 《Molecules (Basel, Switzerland)》2008,13(8):1570-1583
A series of twenty six arylpiperazine and aminoalkanol derivatives of 4-azatricyclo[5.2.2.0(2,6)]undecane-3,5,8-trione have been prepared. The synthesized compounds were evaluated for their cytotoxicity and anti-HIV-1 activity in MT-4 cells. 相似文献
269.
Volha Vetokhina Dr. Krzysztof Dobek Michał Kijak Izabela I. Kamińska Keven Muller Prof. Werner R. Thiel Prof. Jacek Waluk Prof. Jerzy Herbich 《Chemphyschem》2012,13(16):3661-3671
Studies of 2‐(1H‐pyrazol‐5‐yl)pyridine (PPP) and its derivatives 2‐(4‐methyl‐1H‐pyrazol‐5‐yl)pyridine (MPP) and 2‐(3‐bromo‐1H‐pyrazol‐5‐yl)pyridine (BPP) by stationary and time‐resolved UV/Vis spectroscopic methods, and quantum chemical computations show that this class of compounds provides a rare example of molecules that exhibit three types of photoreactions: 1) excited‐state intramolecular proton transfer (ESIPT) in the syn form of MPP, 2) excited‐state intermolecular double‐proton transfer (ESDPT) in the dimers of PPP in nonpolar media, as well as 3) solvent‐assisted double‐proton transfer in hydrogen‐bonded 1:1 complexes of PPP and MPP with alcoholic partners. The excited‐state processes are manifested by the appearance of a dual luminescence and a bimodal irreversible kinetic coupling of the two fluorescence bands. Ground‐state syn–anti equilibria are detected and discussed. The fraction of the higher‐energy anti form varies for different derivatives and is strongly dependent on the solvent polarity and hydrogen‐bond donor or acceptor abilities. 相似文献
270.
Kaminska I Das MR Coffinier Y Niedziolka-Jonsson J Woisel P Opallo M Szunerits S Boukherroub R 《Chemical communications (Cambridge, England)》2012,48(9):1221-1223
A one step process for simultaneous reduction and functionalization of graphene oxide using tetrathiafulvalene (TTF) is described. Chemical oxidation of TTF to TTF(2+) using an aqueous solution of Fe(ClO(4))(3) expels the charged molecule from the graphene nanosheets, while subsequent immersion in neutral TTF solution allows the capture of the TTF molecules. 相似文献