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131.
By using Mn2+ and Mn3+ salts, and freshly extracted ovalbumin, Mn3O4 nanocrystals have been synthesized successfully. The X-ray diffraction results indicated that the synthesized nanoparticles have only the spinel structure without the presence of any other phase impurities. As the ovalbumin–water mixture was highly basic, the process did not require any use of base to increase the pH where hydrolysis took place. A gel formed where water soluble ovalbumin proteins served as a perfect matrix for entrapment of metal ions (Mn2+ and Mn3+). Upon heat treatment, the dried gel precursor decomposed into nanocrystalline Mn3O4. The discrepancy between the crystallite size from XRD and particle size SEM analysis reveals polycrystalline nature of the synthesized particles with this route. EPR analysis of Mn3O4 shows a narrow and symmetric line indicating the absence of hyperfine splitting. 相似文献
132.
Sinem Sipahioglu Kara Mustafa Yasin Ate Gozde Deveci Ahmet Cetinkaya Muhammet U. Kahveci 《Journal of polymer science. Part A, Polymer chemistry》2019,57(6):673-680
Tetrazine mediated inverse Electron Demand Diels–Alder Reaction (IEDDA) is an important modification technique due to its high selectivity and super‐fast kinetics. Incorporation of tetrazine moieties on polymer chains requires multistep synthetic pathways and a post‐polymerization step leading to functional polymeric materials. Such approaches involve separate syntheses of polymer and the molecule which will be employed in modification. Herein, we introduce a straightforward synthetic approach for direct synthesis of tetrazine groups on polymers as side chains. As model systems, tetrazine functional poly(N‐isopropylacrylamide)‐and poly(ethylene glycol)‐based polymers from corresponding precursor polymers with nitrile moieties as pendant groups are prepared and IEDDA Click Reaction is achieved with trans‐cyclooctene derivatives. The click reaction is monitored by both NMR and UV–vis spectroscopies. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 673–680 相似文献
133.
134.
Synthesis, UV–Vis spectra, and Hammett correlation of some novel bis(dihydropyrrolo[3,4-c]pyrazoles)
Abstract
Twenty-nine novel bis(dihydropyrrolo[3,4-c]pyrazole) derivatives were obtained by reacting C,N-phenyl-substituted nitrilimines generated in situ from corresponding hydrazonyl chlorides with bismaleimides. The structures were elucidated by physical and spectroscopic methods [m.p., R f, infrared (IR), 1H nuclear magnetic resonance (NMR), 13C NMR, correlation spectroscopy (COSY), heteronuclear correlation (HETCOR), nuclear Overhauser effect (NOE), and high-resolution mass spectrometry (HRMS)]. Also, Hammett correlation graphs were obtained between Hammett constants σ p and λ max values of bis(pyrrolopyrazoles) carrying p-substituted phenyl-ring-bearing electron-withdrawing and electron-donating groups and discussed in terms of substituent effects. 相似文献135.
Muhammet Yürüsoy 《International Journal of Non》2004,39(4):665-672
The two-dimensional equations of motions for the slowly flowing and heat transfer in second grade fluid are written in cartesian coordinates neglecting the inertial terms. When the inertia terms are simply omitted from the equations of motions the resulting solutions are valid approximately for Re?1. This fact can also be deduced from the dimensionless form of the momentum and energy equations. By employing Lie group analysis, the symmetries of the equations are calculated. The Lie algebra consist of four finite parameter and one infinite parameter Lie group transformations, one being the scaling symmetry and the others being translations. Two different types of solutions are found using the symmetries. Using translations in x and y coordinates, an exponential type of exact solution is presented. For the scaling symmetry, the outcoming ordinary differential equations are more involved and only a series type of approximate solution is presented. Finally, some boundary value problems are discussed. 相似文献
136.
YusufYayli NergizYaz MuratKemalKaracan ZHOUZhe-wei 《应用数学和力学(英文版)》2004,25(8):898-902
Quaternion is a division ring. It is shown that planes passing through the origin can be made a field with the quaternion product in R3. The Hamiltonian operators help us define the homothetic motions on these planes. New characterizations for these motions are investigated. 相似文献
137.
138.
Muhammet U. Kahveci Zeynep Beyazkilic Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2010,48(22):4989-4994
A novel method for the preparation of poly(acrylamide) cryogels by photoinitiated polymerization of monomeric precursors was described. A series of poly(acrylamide) cryogels were easily prepared by irradiating aqueous solutions containing acrylamide and N,N′‐methylene(bis)acrylamide as monomer and cross‐linker, respectively, in the presence of 1‐[4‐(2‐hydroxyethoxy)phenyl]‐2‐hydroxy‐2‐methyl‐1‐propane‐1‐one (Irgacure 2959) as water‐soluble photoinitiator with the help of freezing–thawing procedures. Photolysis was conducted at ?13 °C isothermally through specially designed cryostat‐integrated Rayonet merry‐go‐round photoreactor. On comparing the described photochemical method with the conventional redox counter part, the polymerization is initiated, and gelation proceeds only on external stimulation by light. This way, concomitant hydrogel formation usually observed with the redox process as a result of premature polymerization during the cooling process was prevented. The obtained cryogels exhibited superfast swelling behavior. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
139.
Holten-Andersen N Mates TE Toprak MS Stucky GD Zok FW Waite JH 《Langmuir : the ACS journal of surfaces and colloids》2009,25(6):3323-3326
The cuticle of mussel byssal threads is a robust natural coating that combines high extensibility with high stiffness and hardness. In this study, fluorescence microscopy and elemental analysis were exploited to show that the 3,4-dihydroxyphenyl-l-alanine (dopa) residues of mussel foot protein-1 colocalize with Fe and Ca distributions in the cuticle of Mytilus galloprovincialis mussel byssal threads. Chelated removal of Fe and Ca from the cuticle of intact threads resulted in a 50% reduction in cuticle hardness, and thin sections subjected to the same treatment showed a disruption of cuticle integrity. Dopa-metal complexes may provide significant interactions for the integrity of composite cuticles deformed under tension. 相似文献
140.
We have developed the first example of hypervalent iodine(V)-catalyzed regioselective oxidation of phenols to o-quinones. Various phenols could be oxidized to the corresponding o-quinones in good to excellent yields using catalytic amounts of sodium salts of 2-iodobenzenesulfonic acids (pre-IBSes) and stoichiometric amounts of Oxone? as a co-oxidant under mild conditions. The reaction rate of IBS-catalyzed oxidation under nonaqueous conditions was further accelerated in the presence of an inorganic base such as potassium carbonate (K?CO?), a phase transfer catalyst such as tetrabutylammonium hydrogen sulfate (nBu?NHSO?), and a dehydrating agent such as anhydrous sodium sulfate (Na?SO?). 相似文献