Determination of phenolic components in ethanolic extracts from wood of Maackia amurensis

The phenolic components in an ethanolic extract from the wood of Amur maackia were determined quantitatively by the HPLC method in the isocratic regime using a column with a C₁₉ reversed-phase sorbent and β-naphthol acetate as internal standard. Before injection into the chromatographic column, the extract was purified on a column of Florisil that had been treated with 30% acetic acid. The relative error in the determination of each component at a confidence level of 0.95 does not exceed 7%.     

Studies of V?Mo?O systems with small vanadium content in acrolein oxidation

A solid solution of vanadium in MoO₃ with a solubility limit of about 3 mol.% V₂O₅ is shown to be formed. Its catalytic properties are discussed.

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MoO₃ 3 . % V₂O₅ .

     

Magnetic switch of permeability for polyelectrolyte microcapsules embedded with Co@Au nanoparticles

We explored using a magnetic field to modulate the permeability of polyelectrolyte microcapsules prepared by layer-by-layer self-assembly. Ferromagnetic gold-coated cobalt (Co@Au) nanoparticles (3 nm diameter) were embedded inside the capsule walls. The final 5 mum diameter microcapsules had wall structures consisting of 4 bilayers of poly(sodium styrene sulfonate)/poly(allylamine hydrochloride) (PSS/PAH), 1 layer of Co@Au, and 5 bilayers of PSS/PAH. External alternating magnetic fields of 100-300 Hz and 1200 Oe were applied to rotate the embedded Co@Au nanoparticles, which subsequently disturbed and distorted the capsule wall and drastically increased its permeability to macromolecules like FITC-labeled dextran. The capsule permeability change was estimated by taking the capsule interior and exterior fluorescent intensity ratio using confocal laser scanning microscopy. Capsules with 1 layer of Co@Au nanoparticles and 10 polyelectrolyte bilayers are optimal for magnetically controlling permeability. A theoretical explanation was proposed for the permeability control mechanisms. "Switching on" of these microcapsules using a magnetic field makes this method a good candidate for controlled drug delivery in biomedical applications.     

New phosphate fluorosurfactants for carbon dioxide

Anionic phosphate fluorosurfactants were shown to self-assemble into water-in-carbon dioxide microemulsions. The surfactants, having either two fluorinated chains or one fluorinated chain and one hydrocarbon chain, facilitated significant water uptake in CO2. Small angle neutron scattering (SANS) measurements of surfactant/water/CO2 solutions confirmed the presence of nanometer-scale aggregates, indicative of microemulsion formation.     

Adiabatic perturbation theory for the degenerate case. II. Perturbation of degenerate bound states embedded in the continuum

An adiabatic formula for the contracted Hamiltonian in a reference space containing bound-state eigenfunctions of degenerate energy levels embedded in the continuum is derived. A general factorization theorem for the dynamic operatorS_α(0, – ∞/λ) is proved, and the cancellation of the pole singularities in the perturbation series of the contracted Hamiltonian in adiabatic form is discussed.     

Sorption equilibrium of methanol on new composite sorbents “CaCl<Subscript>2</Subscript>/silica gel”

This paper presents experimental data on methanol sorption on new composite sorbents which consist of mesoporous silica gels and calcium chloride confined to their pores. Sorption isobars and XRD analysis showed the formation of a solid crystalline solvate CaCl₂⋅2MeOH at low methanol uptake, while at higher uptake the formation of the CaCl₂–methanol solution occurred. The solution confined to the silica pores showed the sorption properties similar to those of the CaCl₂–methanol bulk solution. Calorimetric and isosteric analyses showed that the heat of methanol sorption depends on the methanol uptake, ranging from 38±2 kJ/mol for the solution to 81±4 kJ/mol for the solid crystalline phase CaCl₂⋅2MeOH. The above mentioned characterizations allowed the evaluation of the methanol sorption and the energy storage capacities, clearly showing that the optimal applications of these new composite sorbents are the methanol removal from gaseous mixtures, heat storage and sorption cooling driven by low temperature heat.     

The wave logic of consciousness: A hypothesis

A physical model is proposed for volitional decision making. It is postulated that consciousness reducesdoubt states of the brain into labels by a quantum-mechanical measurement act offree choice. Elementary doubt states illustrate analogical encodement of information having insufficient resolution from a classical viewpoint. Measures ofcertitude (inner conviction) and doubt are formulated. Adequate propositions for nonclassical statements, e.g., Hamlet's soliloquy, are constructed. A role is proposed for the superposition principle in imagination and creativity. Experimental predictions are offered for positive and negative interference of doubts. Necessary criteria are made explicit for doubting sense information.Wholeness of perception is illustrated using irreducible, unitary representations ofn-valued logics. The interpreted formalism includes nonclassical features of doubt, e.g., scalor representations for imprecise propositions and state changes due to self-reflection. The liar paradox is resolved. An internal origin is suggested for spinor dichotomies, e.g., true-false and good-bad, analogous to particle production.Translated by Valentin Turchin, with editorial assistance by Eddie Oshins; abstract supplied by Eddie Oshins.     

Simple test system for single molecule recognition force microscopy

We have established an easy-to-use test system for detecting receptor-ligand interactions on the single molecule level using atomic force microscopy (AFM). For this, avidin-biotin, probably the best characterized receptor-ligand pair, was chosen. AFM sensors were prepared containing tethered biotin molecules at sufficiently low surface concentrations appropriate for single molecule studies. A biotin tether, consisting of a 6 nm poly(ethylene glycol) (PEG) chain and a functional succinimide group at the other end, was newly synthesized and covalently coupled to amine-functionalized AFM tips. In particular, PEG₈₀₀ diamine was glutarylated, the mono-adduct NH₂-PEG-COOH was isolated by ion exchange chromatography and reacted with biotin succinimidylester to give biotin-PEG-COOH which was then activated as N-hydroxysuccinimide (NHS) ester to give the biotin-PEG-NHS conjugate which was coupled to the aminofunctionalized AFM tip. The motional freedom provided by PEG allows for free rotation of the biotin molecule on the AFM sensor and for specific binding to avidin which had been adsorbed to mica surfaces via electrostatic interactions. Specific avidin-biotin recognition events were discriminated from nonspecific tip-mica adhesion by their typical unbinding force (∼40 pN at 1.4 nN/s loading rate), unbinding length (<13 nm), the characteristic nonlinear force-distance relation of the PEG linker, and by specific block with excess of free d-biotin. The convenience of the test system allowed to evaluate, and compare, different methods and conditions of tip aminofunctionalization with respect to specific binding and nonspecific adhesion. It is concluded that this system is well suited as calibration or start-up kit for single molecule recognition force microscopy.     

Dispersion of the local parameters of quasilocalized low-frequency vibrational modes in a low-temperature glass: direct observation via single-molecule spectroscopy

Spectra of single tetra-tert-butylterrylene chromophore molecules embedded in an amorphous polyisobutylene matrix as microprobes were recorded. The individual temperature dependences of the spectral linewidths for the same single molecules (SMs) in a broad temperature interval (1.6 < T < 40 K) have been measured. This enabled us to separate the contributions of tunneling two-level systems and quasilocalized low-frequency vibrational modes (LFMs) to the observed linewidths. The analysis of the T dependences yields the values of LFM frequencies and SM-LFM coupling constants for the LFMs in the local environment of a given chromophore. Pronounced distributions of the observed parameters of LFMs were found. This result can be regarded as the first direct experimental proof of the localized nature of LFMs in glasses.