排序方式: 共有41条查询结果,搜索用时 15 毫秒
1.
Rastislav Varga Arcady Zhukov Michail Ipatov Juan Maria Blanco Julian Gonzalez Valentina Zhukova Pavol Vojtanik 《Journal of magnetism and magnetic materials》2006
The effect of the glass coating on the single domain wall potential in amorphous glass-coated Fe-based microwire has been studied by the switching field distribution technique. The thermoactivated mechanism model is used to describe the thermally activated switching through the complex energy barrier in amorphous FeSiB microwires. Glass removal leads to the increase of the probability of the thermally activated switching pointing to the decrease of the energy barrier. 相似文献
2.
Polymeric molecules containing multiple thiol groups (polythiols) provide tenacious attachment to metal surfaces such as gold. Polythiol films are also well suited for subsequent derivatization with biomacromolecules through remnant free thiol groups of the film. In this study, 1-3 nm thick layers of a commercial polythiol, poly((mercaptopropyl)methylsiloxane) (PMPMS), are investigated with X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy. XPS is used to reveal the surface coverage of thiolate-Au bonds between the polythiol and the metal support, which is found to be approximately 30% lower than that in alkanethiol self-assembled monolayers. The surface density of thiolate-Au bonds did not depend on film thickness provided sufficient PMPMS material was present. Differential capacitance measurements show that the effective dielectric barrier presented by PMPMS films under aqueous environments corresponds closely to their physical thickness, with even approximately 1 nm films remaining impermeable to electrolyte species. Modification of the films with an oligoethylene glycol compound was also examined, in anticipation of future applications in label-free, impedance-based biomolecular diagnostics. 相似文献
3.
Reaction of N-phenyl maleimide (NPM) with silica surfaces modified with a self-assembled monolayer of (aminopropyl)triethoxysilane (APTES) was investigated using infrared spectroscopy (FTIR), elemental analysis, and titration assays. This reaction is of interest as a test case for using amine-maleimide coupling for immobilization of biomolecules. Addition of NPM to surface APTES residues was consistently sub-stoichiometric, with typical yields of about 75% on monolayers with a coverage of 1.15 APTES residues/nm2. Titration analysis found negligible presence of imide alkene C=C bonds in modified supports, indicating that addition of NPM to APTES proceeded via amine attack at the imide olefinic bond. FTIR measurements also revealed presence of amide bands which intensified over periods of 10 h. These observations were attributed to a slower secondary process in which APTES amines attack imide carbonyls to produce amide linkages. Stability of NPM-modified surfaces was examined under room temperature storage in pH 7 buffer up to 72 h and for 2 h exposure to buffer at temperatures up to 90 degrees C. It was found that stability was determined by robustness of APTES-silica attachment, with about 30% loss under the harshest conditions investigated. 相似文献
4.
Ján Kova Jaromír Mike Rastislav Jendelovský Martin Kello Peter Solár Peter Fedoroko 《Photochemistry and photobiology》2010,86(1):200-205
Current treatment of breast cancer is often affected by resistance to therapeutics, for which the human epidermal growth factor receptor 2 (HER2) may be responsible. Here, we report for the first time the use of hypericin-mediated photodynamic therapy (HY-PDT) in combination with a selective HER2 inhibitor (AG 825) on SKBR-3, a HER2 overexpressing human breast adenocarcinoma cell line. The results demonstrate that HY-PDT is able to degrade HER2 with an impact on its signaling cascade. Combination with AG 825 resulted in increased apoptosis induction, total degradation of HER2 and inhibition of colony formation. Downregulation of HSP90, Mcl-1, Bcl-xL and upregulation of Bax was also observed. This knowledge provides the basis for the possible application of HY-PDT in preclinical and clinical models of breast cancer treatment. 相似文献
5.
Perry de Valpine Daniel Turek Christopher J. Paciorek Clifford Anderson-Bergman Duncan Temple Lang Rastislav Bodik 《Journal of computational and graphical statistics》2017,26(2):403-413
We describe NIMBLE, a system for programming statistical algorithms for general model structures within R. NIMBLE is designed to meet three challenges: flexible model specification, a language for programming algorithms that can use different models, and a balance between high-level programmability and execution efficiency. For model specification, NIMBLE extends the BUGS language and creates model objects, which can manipulate variables, calculate log probability values, generate simulations, and query the relationships among variables. For algorithm programming, NIMBLE provides functions that operate with model objects using two stages of evaluation. The first stage allows specialization of a function to a particular model and/or nodes, such as creating a Metropolis-Hastings sampler for a particular block of nodes. The second stage allows repeated execution of computations using the results of the first stage. To achieve efficient second-stage computation, NIMBLE compiles models and functions via C++, using the Eigen library for linear algebra, and provides the user with an interface to compiled objects. The NIMBLE language represents a compilable domain-specific language (DSL) embedded within R. This article provides an overview of the design and rationale for NIMBLE along with illustrative examples including importance sampling, Markov chain Monte Carlo (MCMC) and Monte Carlo expectation maximization (MCEM). Supplementary materials for this article are available online. 相似文献
6.
Madjid Hadioui Med Oimar Mecherri Rastislav Šípoš Yan Yvon Patrick Sharrock 《Chemical Papers》2011,65(6):855-862
Glycidoxypropyltriethoxysilane (GPS) was used as a reactive silane to graft metal- complexing ligands onto silica gel in aqueous
media under mild conditions. The synthesis entailed the reaction of GPS with silica gel, followed by grafting polyamine onto
the epoxy functional group. GPS was added to silica gel in ethanol with 5 vol. % water and the mixture was air-dried for 24
h. Subsequently, excess amounts of polyamines: triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine were
individually added to the silanised silica, followed by solvent evaporation and ovendrying at 60°C. The ligand-grafted silica
gel particles showed a rapid heavy metal uptake in batch or flow-through experiments with capacities reaching 0.1 mmol g−1 for copper, zinc, cadmium, or lead ions. Columns packed with the modified particles could be readily regenerated by acid-washing
with only a small decrease in activity. The particles could be used for the colourimetric detection of heavy metal pollution
or for pre-concentration for analytical purposes. Competition between Cu2+, Zn2+, Pb2+, and Cd2+ ions for the three synthesised silica showed that Cu2+ ions were adsorbed more strongly than the other metal ions. The general method developed can be applied to graft other molecules
with terminal amino groups for other purposes. 相似文献
7.
Milan Stehlík Rastislav Potocký Helmut Waldl Zdeněk Fabián 《Computational Statistics》2010,25(3):485-503
Assessment of heavy tailed data and its compound sums has many applications in insurance, auditing and operational risk capital
assessment among others. In this paper, we compare the classical estimators (maximum likelihood, QQ and moment estimators)
with the recently introduced robust estimators of “generalized median”, “trimmed mean” and estimators based on t-score moments.
We derive the exact distribution of the likelihood ratio tests of homogeneity and simple hypothesis on the tail index of a
two-parameter Pareto model. Such exact tests support the assessment of the performance of estimators. In particular, we discuss
some problems that one can encounter when misemploying the log-normal assumption based methods supported by the Basel II framework.
Real data and simulated examples illustrate the methods. 相似文献
8.
Effrosyni Zafeiraki Rastislav Sabo Konstantinos M. Kasiotis Kyriaki Machera Lucia Sabov Tom Majchrk 《Molecules (Basel, Switzerland)》2022,27(19)
Bees in search of diet sources intensively fly within a radius of up to 3 km, encountering nectar, pollen, and water sources which are potentially contaminated. Consequently, their products can provide valuable information about potential pollution. In the current study, 27 macro and trace elements, including the most hazardous ones, were measured in bees, honey, wax, pollen, and larvae, obtained from seven explicitly industrial areas in eastern regions of Slovakia, using a validated ICP-MS method. All the analysed elements were detected at least in one matrix. The detected concentrations of toxic elements, such as Hg, Pb, and Cd were in some cases higher in wax and bee samples, compared with honey, larvae, and pollen. In particular, Pb and Hg maximum concentrations were detected in the wax samples from Poša (3193 µg/kg) and Strážske_A (90 μg/kg). In addition, adult bees accumulated more elements than larvae, while wax and adult bees seemed more suitable for monitoring macro and trace elements in the surrounding environment. Statistical analysis emphasizing bees and wax correlated Cd with the Strážske area, possibly attributed to the intensified industrial activity in this region. 相似文献
9.
The Molecular and Crystal Structures of 2-Iodokojic Acid: Experimental and Theoretical Determination
František Šimo Ján Moncol Rastislav Šípoš Zdeňka Padělková Jozef Šima 《Journal of chemical crystallography》2011,41(8):1093-1098
Abstract
The crystal structure of 2-iodokojic acid, (2-jodo-3-hydroxy-6-hydroxymethyl)-4-H-pyran-4-one) (C6H5IO4, Mr = 268.00) has been determined by single crystal X-ray diffraction analysis. The compound crystallizes in the orthorhombic crystal system with space group Pc21b and unit cell parameters: a = 4.0830(2), b = 15.3510(5), c = 23.517(1) ? and Z = 8. The final reliability index is 0.0288 for 2,584 observed reflections. The two molecules of iodokojic acid, slightly differing in their molecular structure, are localized in independent part of unit cell. The crystal packing is stabilized by O–H···O hydrogen bonds and I···O intermolecular interactions. The molecular structure of iodokojic acid determined experimentally little differs from that obtained by the applied theoretical (Hartree–Fock and four versions of DFT) methods, the differences should not be taken as a measure of the reliability of the theoretical methods. 相似文献10.