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461.
462.
Dr. Jarosław J. Panek Dr. Aneta Jezierska‐Mazzarello Prof. Aleksander Koll Prof. Galina Dovbeshko Dr. Olena Fesenko 《Chemphyschem》2011,12(13):2485-2495
Adsorption of guest molecules on host surfaces can lead to dramatic changes in the spectral properties of the guest. One such effect is surface‐enhanced infrared absorption (SEIRA), observed when the guest is adsorbed on, for example, thin films, metal surfaces, or nanotubes. p‐Nitrobenzoic acid (p‐NBA) exhibits a SEIRA effect when adsorbed on Ag and Au. Herein, the IR spectra of p‐NBA adsorbed on a homemade rough Au surface, recorded in reflection mode with an angle of incidence of 16.5°, are reported. This SEIRA experiment reveals more bands than found by previous SEIRA studies. The intensities of both symmetric and asymmetric COO? and NO2 stretching, in‐plane CH, and C?C ring stretching modes are enhanced. Theoretical models constructed on the basis of density functional theory reveal the binding mode of p‐NBA to gold “particles”. The p‐NBA anion binds to gold much more strongly than the neutral form, and interaction via the carboxylic oxygen atoms is preferred over the nitro group–gold contact. A significant charge transfer during chemisorption is found, which is considered to be crucial in leading to a high SEIRA enhancement factor. 相似文献
463.
Trummal A Rummel A Lippmaa E Koppel I Koppel IA 《The journal of physical chemistry. A》2011,115(24):6641-6645
Acidity calculations for some CH and NH superacids in 1,2-dichloroethane (DCE) were carried out using SMD and COSMO-RS continuum solvation models. After comparing the results of calculations with respective experimental pK(a) values it was found that the performance of SMD/M05-2X/6-31G* method is characterized by the mean unsigned error (MUE) of 0.5 pK(a) units and the slope of regression line of 0.915. The similar SMD/B3LYP/6-31G* approach was slightly less successful. The strong correlation over entire data set is confirmed by R(2) values of 0.990 and 0.984 for M05-2X and B3LYP functionals, respectively. The COSMO-RS method, while providing the value of the linear regression line slope similar to the corresponding values from SMD approach, characterized by rather loose correlation (R(2) = 0.823, MUE = 1.7 pK(a) units) between calculated and experimental pK(a) values in DCE solution. 相似文献
464.
Hydrothermally assisted complex polymerization method for barium strontium titanate powder synthesis
Jovana Ćirković Katarina Vojisavljević Maja Šćepanović Aleksander Rečnik Goran Branković Zorica Branković Tatjana Srećković 《Journal of Sol-Gel Science and Technology》2013,65(2):121-129
Barium strontium titanate was obtained by hydrothermal treatment of barium strontium titanate citric precursor solution, previously prepared by complex polymerization method. The thermally induced phase evolution was followed at various temperatures up to 800 °C using thermogravimetric and differential thermal analysis, X-ray diffraction analysis, and Raman spectroscopy. Microstructural characterization of barium strontium titanate powders was performed by scanning and transmission electron microscopy. The proposed synthesis route has been proven as a better and faster method for barium strontium titanate powder preparation as compared to the conventional complex polymerization route. The method was found efficient for production of low agglomerated, fine, nanosized barium strontium titanate powder with well defined stoichiometry, and sub-micron particle size. The results of structural and microstructural characterization showed the complete crystallization of carbonate-free barium strontium titanate powder at 700 °C with an average size of crystallites below 50 nm. 相似文献
465.
A series of isostructural oxalates of Th, U, Np, and Pu have been synthesized. The crystal structure of {C(NH(2))(3)}(4)[An(C(2)O(4))(4)]·2H(2)O comprises infinite [An(C(2)O(4))(4)](4n-) chains, guanidinium cations and water molecules. Each An atom is connected to five oxalate anions, two of which act as bridging tetradentate ligands, while the other three function as terminating bidentate ligands. Electron and IR spectra of the compounds as well as the results of thermal analysis correlate with their structure. An actinide contraction effect is demonstrated by a decrease in the An-O interatomic distances and the volumes of An atom coordination polyhedra and Voronoi-Dirichlet polyhedra. Ten-coordinate An oxalates are discussed in terms of continuous shape measures approach. 相似文献
466.
Janusz W. Strzelecki Joanna Strzelecka Karolina Mikulska Mariusz Tszydel Aleksander Balter Wiesław Nowak 《Central European Journal of Physics》2011,9(2):482-491
Caddisfly (Trichopera) can glue diverse material underwater with a silk fiber. This makes it a particularly interesting subject
for biomimetcs. Better understanding of silk composition and structure could lead to an adhesive capable to close bleeding
wounds or to new biomaterials. However, while spiderweb or silkworm secretion is well researched, caddisfly silk is still
poorly understood. Here we report a first nanomechanical analysis of H. Angustipennis caddisfly silk fiber. An Atomic Force
Microscope (AFM) imaging shows dense 150 nm bumps on silk surface, which can be identified as one of features responsible
for its outstanding adhesive properties. AFM force spectroscopy at the fiber surface showed, among others, characteristic
saw like pattern. This pattern is attributed to sacrificial bond stretching and enhances energy dissipation in mechanical
deformation. Similarities of some force curves observed on Tegenaria domestica spiderweb and caddisfly silk are also discussed.
Steered Molecular Dynamics simulations revealed that the strength of short components of Fib-H HA species molecules, abundant
in Trichoptera silk is critically dependent on calcium presence. 相似文献
467.
Stationary Solutions and Connecting Orbits for <Emphasis Type="Italic">p</Emphasis>-Laplace Equation
Aleksander Ćwiszewski Mateusz Maciejewski 《Journal of Dynamics and Differential Equations》2018,30(1):309-329
We deal with one dimensional p-Laplace equation of the form under Dirichlet boundary condition, where \(p>2\) and \(f:[0,l]\times {\mathbb {R}}\rightarrow {\mathbb {R}}\) is a continuous function with \(f(x,0)=0\). We will prove that if there is at least one eigenvalue of the p-Laplace operator between \(\lim _{u\rightarrow 0} f(x,u)/|u|^{p-2}u\) and \(\lim _{|u|\rightarrow +\infty } f(x,u)/|u|^{p-2}u\), then there exists a nontrivial stationary solution. Moreover we show the existence of a connecting orbit between stationary solutions. The results are based on Conley index and detect stationary states even when those based on fixed point theory do not apply. In order to compute the Conley index for nonlinear semiflows deformation along p is used.
相似文献
$$\begin{aligned} u_t = (|u_x|^{p-2} u_x )_x + f(x,u), \ x\in (0,l), \ t>0, \end{aligned}$$
468.
Aleksandra A. Chaikovskaya Yurii V. Dmytriv Nadiya V. Shevchuk Radomyr V. Smaliy Aleksander M. Pinchuk Andrey A. Tolmachev 《Heteroatom Chemistry》2008,19(7):671-676
A successive N → C2 → C3 migration of the dichlorophosphino group has been found to occur in phosphorylation of unsubstituted pyrrole with phosphorus trichloride. As a result of this migration, a number of hitherto unknown C‐phosphorylated N‐unsubstituted pyrroles have been obtained. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:671–676, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20495 相似文献
469.
Edyta?C?drowska Marek?Pruszynski Agnieszka?Majkowska-Pilip Sylwia?M?czyńska-Wielgosz Frank?Bruchertseifer Alfred?Morgenstern Aleksander?BilewiczEmail author 《Journal of nanoparticle research》2018,20(3):83
The 225Ac radioisotope exhibits very attractive nuclear properties for application in radionuclide therapy. Unfortunately, the major challenge for radioconjugates labelled with 225Ac is that traditional chelating moieties are unable to sequester the radioactive daughters in the bioconjugate which is critical to minimize toxicity to healthy, non-targeted tissues. In the present work, we propose to apply TiO2 nanoparticles (NPs) as carrier for 225Ac and its decay products. The surface of TiO2 nanoparticles with 25 nm diameter was modified with Substance P (5-11), a peptide fragment which targets NK1 receptors on the glioma cells, through the silan-PEG-NHS linker. Nanoparticles functionalized with Substance P (5-11) were synthesized with high yield in a two-step procedure, and the products were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and thermogravimetric analysis (TGA). The obtained results show that one TiO2-bioconjugate nanoparticle contains in average 80 peptide molecules on its surface. The synthesized TiO2-PEG-SP(5-11) conjugates were labelled with 225Ac by ion-exchange reaction on hydroxyl (OH) functional groups on the TiO2 surface. The labelled bioconjugates almost quantitatively retain 225Ac in phosphate-buffered saline (PBS), physiological salt and cerebrospinal fluid (CSF) for up to 10 days. The leaching of 221Fr, a first decay daughter of 225Ac, in an amount of 30% was observed only in CSF after 10 days. The synthesized 225Ac-TiO2-PEG-SP(5-11) has shown high cytotoxic effect in vitro in T98G glioma cells; therefore, it is a promising new radioconjugate for targeted radionuclide therapy of brain tumours. 相似文献
470.
Mikhail V. Kalyaev Dmitry S. Ryabukhin Marina A. Borisova Alexander Yu. Ivanov Irina A. Boyarskaya Kristina E. Borovkova Lia R. Nikiforova Julia V. Salmova Nikolay V. Ulyanovskii Dmitry S. Kosyakov Aleksander V. Vasilyev 《Molecules (Basel, Switzerland)》2022,27(14)
Reactions of 3-(furan-2-yl)propenoic acids and their esters with arenes in Brønsted superacid TfOH affords products of hydroarylation of the carbon–carbon double bond, 3-aryl-3-(furan-2-yl)propenoic acid derivatives. According to NMR and DFT studies, the corresponding O,C-diprotonated forms of the starting furan acids and esters should be reactive electrophilic species in these transformations. Starting compounds and their hydroarylation products, at a concentration of 64 µg/mL, demonstrate good antimicrobial activity against yeast-like fungi Candida albicans. Apart from that, these compounds suppress Escherichia coli and Staphylococcus aureus. 相似文献