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One of the criteria for the development of high-energy processes is the large specific surface area of the solid component of composites. Therefore, the maximum preservation of its nanostructured skeleton when separating the porous layer from the monocrystal substrate is relevant. Based on the analysis of the quality of the porous layer under various methods and modes of its formation, two methods were selected that provide simple and effective separation of the porous structure from the monocrystal. For composites based on mounds of porous silicon (pSi) fragments (MPSF), three series of experiments were carried out with fragments of porous layers of different age (formed within the previously established time limits before composites creation) with registration of combustion dynamics, temperatures and combustion spectra, as well as intensity of disturbances in the atmosphere forming during combustion of MPSF-composites. Four combustion modes of MPSF-composites were established: smoldering, frontal, aerosol, and frontal-aerosol. The ignition induction times were determined: from 1 to 50 ^s, pressure pulses in the atmosphere at a distance of 260 mm from the ignition site - up to 1.6 bar (with a mass of composites up to 0.4 g). Combustion velocities ofMPSF-composites and their dependences onthe coefficient of stoichiometry and humidity of sodium perchlorate monohydrate are established.

The physical mechanism of detonation combustion of nanostructured silicon with a solid-phase oxidant at a velocity of the combustion front of 1000–3000 m/s has been proposed. Thermodynamic characteristics of combustion of model solid-phase mixtures “silicon–ammonium perchlorate” with different equivalent ratios of their components have been calculated at different pressures. It has been established that a characteristic feature of detonation combustion of nanostructured silicon with a solid-phase oxidant is the stationary velocity of motion of the detonation front with a significant defect (10–15%) with respect to the Chapman–Jouguet detonation velocity. The detonation (supersonic) and subsonic regimes of combustion of nanostructured silicon with a solid-phase oxidant have been determined.

Coherent dynamics of lattice oscillations in a ∼20-nm-thick film obtained by thermal sputtering of bismuth is studied using ultrashort electron bunches synchronised with femtosecond laser pulses irradiating the sample. The Fourier analysis of ultrafast electron diffraction (UED) data shows that the observed modulation of the signal is due to the ensemble of modes corresponding to optical phonons with frequencies of approximately 3, 6 and 9 THz. A conclusion is made that these peaks correspond to the manifestation of the bismuth A 1g mode (three-terahertz peak), as well as its first and second overtones, which is probably due to quantum confinement in a 20-nm Bi nanostructure. The possibility of a detailed study of the quantum-size effect in bismuth with the help of a transmission UED is analysed.

Azobenzene/tetraethyl ammonium photochromic ligands (ATPLs) are photoactive compounds with a large variety of photopharmacological applications such as nociception control or vision restoration. Absorption band maximum and lifetime of the less stable isomer are important characteristics that determine the applicability of ATPLs. Substituents allow to adjust these characteristics in a range limited by the azobenzene/tetraethyl ammonium scaffold. The aim of the current study is to find the scope and limitations for the design of ATPLs with specific spectral and kinetic properties by introducing para substituents with different electronic effects. To perform this task we synthesized ATPLs with various electron acceptor and electron donor functional groups and studied their spectral and kinetic properties using flash photolysis and conventional spectroscopy techniques as well as quantum chemical modeling. As a result, we obtained diagrams that describe correlations between spectral and kinetic properties of ATPLs (absorption maxima of E and Z isomers of ATPLs, the thermal lifetime of their Z form) and both the electronic effect of substituents described by Hammett constants and structural parameters obtained from quantum chemical calculations. The provided results can be used for the design of ATPLs with properties that are optimal for photopharmacological applications.

A typical feature of proteins from the rhodopsin family is the sensitivity of their absorption band maximum to protein amino acid composition. For this reason, studies of these proteins often require methodologies that determine spectral shift caused by amino acid substitutions. Generally, quantum mechanics/molecular mechanics models allow for the calculation of a substitution-induced spectral shift with high accuracy, but their application is not always easy and requires special knowledge. In the present study, we propose simple models that allow us to estimate the direct effect of a charged or polar residue substitution without extensive calculations using only rhodopsin three-dimensional structure and plots or tables that are provided in this article. The models are based on absorption maximum values calculated at the SORCI+Q level of theory for cis- and trans-forms of retinal protonated Schiff base in an external electrostatic field of charges and dipoles. Each value corresponds to a certain position of a charged or polar residue relative to the retinal chromophore. The proposed approach was evaluated against an example set consisting of twelve bovine rhodopsin and sodium pumping rhodopsin mutants. The limits of the applicability of the models are also discussed. The results of our study can be useful for the interpretation of experimental data and for the rational design of rhodopsins with required spectral properties.

Numerous studies have demonstrated the potential use of porous silicon (pSi) as an energetic material. However, there are a number of dificulties in such an application of nanostructured silicon. Here are two of the most serious dificulties.

Currently, various groups of scientists are investigating the possibility of using nanostructured porous silicon as promising solid fuels (or additives to composite solid fuels) and as miniature energy sources for microelectromechanical systems. The results presented in the paper demonstrate the prospects of the proposed novations aimed at increasing the efficiency of nanoporous silicon as an energetic material. They are based on the use of mounds of porous silicon fragments treated with sodium perchlorate solutions and dried under low warming (MPSF-composites) as energy composites. For example, when the weights of the MPSF-composites and the porous layer composites on monocrystal substrates treated with sodium perchlorate solutions (PS-composites) are close to each other, the overpressure at the front of the shock waves developing at the initiation and propagation of combustion in the case of MPSF-composites is 5-6 times higher.

The processes of pSi ignition and combustion in oxygen are described. When spark ignition in the porous layer releases the Joule heat, it leads to a significant heating-up of the breakdown region.

The results of experiments on combustion of porous silicon (pSi) layers with a thickness ranging from 19 to 135 pm at oxygen pressure up to 33 bar and spark initiation of the process are presented, as well as the possible modes of pSi combustion in oxygen are indicated.

The modification of a graphene sheet, which was fabricated by chemical vapor deposition on a close-meshed copper grid, during powerful femtosecond laser irradiation is studied. The process of long-term irradiation of a sample in vacuum is found to be accompanied by (1) breaking carbon bonds, which is indicated by a decrease in the intensities of the reflections corresponding to electron-beam diffraction by graphene and (2) the formation of new products, which is indicated by the appearance of new diffraction rings and a change in the Raman spectrum of the sample. The compositions of the forming chemical compounds are analyzed. Copper oxides Cu2O and CuO are shown to form predominantly on the sample surface as a result of the chemical reactions induced by powerful femtosecond laser pulses.

The generation of coherent optical phonons in an antimony film has been directly observed by the femtosecond electron diffraction method. The sample has been excited by a femtosecond laser pulse (λ = 800 nm) and probed with a pulsed photoelectron beam. Oscillations of the intensity corresponding to vibration frequencies of optical phonons excited by the laser have been observed in the obtained diffraction patterns: totally symmetric (A 1g) and twofold degenerate (E 2g) phonon modes of antimony and their combinations.

In this paper, we propose a fast and simple approach for the fabrication of the electrocatalytically active ruthenium-containing microstructures using a laser-induced metal deposition technique. The results of scanning electron microscopy and electrical impedance spectroscopy (EIS) demonstrate that the fabricated ruthenium-based microelectrode had a highly developed surface composed of 10 &mu, m pores and 10 nm zigzag cracks. The fabricated material exhibited excellent electrochemical properties toward non-enzymatic dopamine sensing, including high sensitivity (858.5 and 509.1 &mu, A mM&minus, 1 cm&minus, 2), a low detection limit (0.13 and 0.15 &mu, M), as well as good selectivity and stability.

A conducting organic polymer is visualized on a laser photoelectron projection microscope, which is based on Letokhov’s concept and has a nanometer spatial resolution. Photoelectron images of polyaniline (which is the most promising representative of conducting polymers) with a magnification of ∼105 have been obtained when a 100-nm quartz capillary coated with a film of this material was irradiated by femtosecond laser pulses. The projection photoelectron method using 400- and 800-nm laser radiation has made it possible to directly reveal the existence of the redox heterogeneity of the organic polymer, which is due to the contact of the sections of polyaniline with different oxidation degrees and strongly affects the electric conductivity of the sample.

The integral characteristics of burning of stoichiometric and lean hydrogenous mixtures in a cylindrical chamber at initial pressures of 0.024 to 1 MPa have been investigated. The propagation of the flame has been visualized and the distributions of its velocity and the running parameters of burning have been obtained. It has been shown that in synthesis-gas-based mixtures, the flame front has a "cellular structure;" its characteristic dimension grows with propagation of the flame. A method for determining the shape factor, which makes it possible to explain certain experimental regularities of burning, has been proposed. The results of the work can be used in selecting the parameters of mixtures and combustion chambers of heat engines operating on modified fuels.

With the use of the Vibe formula, the heat release dynamics in the process of combustion of stoichiometric and lean (ϕ = 0.8) propane-hydrogen-air mixtures with a content of molecular hydrogen from 0 to 14% in a cylindrical chamber has been considered. With the aid of the experimental data obtained for the investigated geometry, the relative characteristic of the heat release, the total combustion time, and the index of the combustion character for two variants of the initiator location (lateral and central firing) have been established. It has been shown that these parameters take into account the main features of combustion and have a quite definite physical meaning associated with the physicochemical properties of the fuel and the flame propagation velocity. The heat release rate and its dependence on the time and the position of the flame front have been investigated.

A mixture of 7α- and 17-bromonorambreinolides was obtained on treatment of the mixture of isomeric methyl bicyclohomofarnesenoates, the norambreinolide transesterification product, with NBS and H2O2. The structure of 7α- and 17-bromonorambreinolides was elucidated on the basis of spectral data. The structure of 17-bromonorambreinolide was confirmed by its reduction with LiAlH4 into sclaradiol, and that of 7α-bromonorambreinolide by X-ray analysis.

A nanolocalized electron beam emitted from silicon nanotubes has been used to image the aperture of a quartz capillary with a channel diameter of 100 nm. An analogous nickel-coated capillary was used as a tip for imaging deposited organic nanostructures by means of femtosecond laser photoelectron projection microscopy (LPPM). Organic nanocomplexes deposited onto the tip surface change the dependence of the photoelectron response signal on the energy density of probing femtosecond laser pulses. An analysis of the LPPM images of capillary nanotips shows that the spatial resolution achieved in these experiments is on a level of 5 nm.

The possibility of the desorption of complicated molecular complexes by soft X rays resulting from a solid target irradiated by a single sharply focused femtosecond laser pulse with an energy of several millijoules has been experimentally demonstrated for polyaniline, which is an organic conducting polymer. X-ray desorption and photodesorption of polyaniline by femtosecond laser pulses have been compared using a time-of-flight mass spectrometer. The results provide the possibility of studying surfaces with spatial nanoresolution and high elemental (chemical) selectivity, as well as observing the photodesorption with a high temporal resolution.

Organic nanocomplexes obtained by applying an organic dye (Coumarin 153) solution onto the surface of a metal nanotip were studied by femtosecond laser photoelectron projection microscopy. The tip was a 100-nm-diameter capillary covered with a thin nickel layer. The image of a through hole of the capillary was a convenient reference for interpretation of the results. The spatial resolution achieved in these experiments was equal to about 5 nm.

This work presents the results of an experimental and theoretical investigation of the breakdown of a solid material by shock and detonation waves and the subsequent interaction of the indicated waves with the formed gas suspension cloud.

Nanolocalized ion packets have been produced due to the transmission of photoions, which are emitted from a refractory metal emitter irradiated by femtosecond laser radiation with a high repetition rate, through a quartz nanocapillary. With the use of such a pulsed nanobeam, a miniature ion microscope has been created and the image of a dielectric-nanoaperture fragment has been obtained.

Data on the partial synthesis of enantiomerically pure sesquiterpenoids of the drimane group, including valuable biologically active natural compounds, from accessible labdane diterpenoids are surveyed.

A method was elaborated for the synthesis of polyfunctional compoonds of the drimane series,viz., drim-8(9)-en-7-one, drima-5,8(9)-dien-7-one, and their 11,12-dibromo derivatives, potential intermediates for the synthesis of natural biologically active drimane sesquiterpenoids starting from norambreinolide. The key intermediate of the above drimane compounds is methyl 7-oco-11-homodrim-8(9)-en-12-oate, prepared by electrochemical oxidation of a mixture of isomeric methyl bicyclohomofarnesenoates obtained from norambreinolide.

A method was elaborated for the synthesis of polyfunctional compoonds of the drimane series,viz., drim-8(9)-en-7-one, drima-5,8(9)-dien-7-one, and their 11,12-dibromo derivatives, potential intermediates for the synthesis of natural biologically active drimane sesquiterpenoids starting from norambreinolide. The key intermediate of the above drimane compounds is methyl 7-oco-11-homodrim-8(9)-en-12-oate, prepared by electrochemical oxidation of a mixture of isomeric methyl bicyclohomofarnesenoates obtained from norambreinolide.

Data on the partial synthesis of enantiomerically pure sesquiterpenoids of the drimane group, including valuable biologically active natural compounds, from accessible labdane diterpenoids are surveyed.

The ozonolysis of a mixture of 13Z- and 13E-neoabienols (I and III) leads, depending on the conditions, either to 8α-hydroxy-14,15-bis-norlabd-11-en-13-one (IV) or to 8α-hydroxdriman-11-oic acid (VI) or to driman-8α,11-diol (VII). Compound (IV) undergoes hydrogenation smoothly with the formation of a mixture of 8α-hydroxy-14,15-bisnorlabdan-13-one (X) and “sclareol oxide” (XI).

A four-stage synthesis of (+)-drim-8-en-11-oic acid (IX) from norambreinolide (II) has been developed. The latter was converted by boiling with ethanolic sulfuric acid into a mixture of the methyl esters of bicyclohomofarnes-7- and -8-enoic acids which, on reaction with methyllithium, gave a mixture of 12-methyl-14,15,16-trinorlabd-7-and -8-en-12-ols. The alcohol with the Δ8 double bond was dehydrated with p-toluenesulfonic acid to 11-methyl-14,15,16-trinorlabd-8,11-diene, the ozoization of which yielded (+)-drim-8-en-11-oic acid.

The ozonization of abienol in ethyl acetate in the presence of pyridine or in methanol followed by the reduction of the peroxides by methyl sulfide has given ambreinolide. On reduction of the peroxide products of the ozonolysis of isoabienol in methanol with potassium tetrahydroborate, the main reaction product was 15,16-bisnorlabdane-8,13,14-triol. Dimethyl sulfide first caused the rearrangement of the peroxide products of ozonization with the cleavage of the ordinary C-13-C-14 carbon bond, and then their reduction.

A synthetic route to 11-hydroxydrim-8(9)-en-7-one and 11,12-hydroxydrim-8(9)-en-7-one, valuable key intermediates for the preparation of naturally occurring biologically active drimanic sesquiterpenoids, starting from easily available drim-8(9)-en-7-one was developed. 11-Hydroxydrim-8(9)-en-7-one was obtained by peracidic oxidation of the enol acetate of drim-8(9)-en-7-one. 11,12-Dihydroxydrim-8(9)-en-7-one was synthesized from drim-8(9)-en-7-one by two routes, namely, by a five-step procedurevia 11-hydroxydrim-8(9)-en-7-one and by bromination of drim-8(9)-en-7-one with NBS to give 11,12-dibromodrim-8(9)-en-7-one followed by its acetoxylation and deacetylation.

It is shown that field emission microscopy and related methods can be used to analyze the metal coated fiber tips, which nowadays are the most frequently used sensor for the scanning near-field optical microscopy (SNOM). Metal free and thus non field-emitting aperture for the light transmission on the tip apex can be directly seen and its parameters can be measured, which is very important for the interpretation of SNOM data.

A five-stage synthesis of 8α-acetoxydriman-11-oic acid from the readily available bicyclohomofarnesane-8α,12-diol has been developed.

Double stranded multimers (C2A6C2)n, (C2A6G2)n and (G2A6G2)n were prepared from chemically synthesized oligonucleotides to study the influence of sequences flanking the An tract on the curvature of DNA. All these duplexes, including polypurine.polypyrimidine one, exhibit strong retardation in polyacrylamide gel which is indicative of pronounced DNA curvature. It has been proposed previously that among the bends at the boundary with the oligo(A) tract two types should be distinguished: 5'-bends and 3'-bends (Koo et al., 1986) This distinction was deduced from different relative mobilities of two specially designed sequences having phased 5'-bends and 3'-bends, respectively. Our data indicate that the substitutions of nucleotides at both 5' and 3' boundaries of A6 tract result in comparable changes in relative mobility. Therefore, for B-B' bends it is important to take into account not only whether they are at the 5' or 3' end of an oligo(dA) tract, but also the particular sequences at the boundaries of this tract.

1. Steel 09G2S with ferritic-martensitic structure, subjected to stipulated thermoplastic strengthening (STPS), has high indices of structural strength; this opens up prospects of its use in building structures and pipelines. 2. As a result of STPS, consisting in combined deformation at temperatures of the austenitic region and of the intercritical interval, the structural components of the dualphase steel 09G2S become refined and a substructure forms in the ferrite; this doubles the threshold value of the stress intensity factor and reduces by a factor of about 1.8 the speed of fatigue crack propagation under cyclic load in comparison with the analogous characteristics of steel treated by the standard regime. At that σu increases from 800 to 880 N/mm2;δ from 540 to 650 N/mm2; δ from 17 to 19%.

The authors measured the differential and integral cross sections for the inelastic scattering of neutrons by niobium through the time-of-flight method on a spectrometer at the KG-0.3 accelerator. The flux of primary neutrons was obtained from the /sup 3/T(d, n)/sup 4/He reaction. A detailed description of the spectrometer, the electronics, and the measurement procedure is presented.

The problem of suppressing the background from accompanying processes in recording ionizing radiation arises fairly frequently. In determining the composition of a mixture of fissile nuclides in spent reactor fuel from the fall in the delayed-neutron flux [i], a pronounced background may be produced by instantaneous neutrons in the spontaneous fission of isotopes of plutonium, curium, californium, etc.

On the bas i s of expe r imen ta l data on the in t ens i t i e s and depo la r i za t ion of the l i nes , and a theore t ica l ca l cu la t ion of the f r equenc ies of the v ib ra t ions of s y m m e t r y type Blu, they ass igned the v ib ra t iona l f r equenc ie s of py rene to defini te s y m m e t r y types . Zhi rnov [2] made a theore t i ca l study of the v i b r a t ional s p e c t r u m of coronene . The study was based on the a s s u m p t i o n that the re a re no 7r-electron bonds between the cen t ra l "benzene" and pe r iphe ra l "coronene" r ings , and that the force i n t e r ac t i on between them is equal to zero . In the model adopted, the force field of the cen t r a l r i ng is de sc r ibed by the s y s t e m of force cons tan t s for benzene . The ca lcu la t ion c a r r i e d out for the Six v ib ra t iona l f r equenc i e s of s y m m e t r y type Alg provided a qual i ta t ive exPlanat ion for the r ep roduc t ion of v a r i o u s v i b r a t i o n a l f r equenc ies of the s p e c t r u m of benzene in the v ib ra t iona l s p e c t r u m of coronene . As f a r as we know, the v ib ra t iona l s p e c t r u m of pe ry lene has not been ca lcula ted . It is well known that a r e l i ab l e i n t e r p r e t a t i o n of the v ib ra t iona l spec t r a of molecu les is poss ib le only on the bas i s of a theore t i ca l ca lcu la t ion of the f r equenc ie s of the v ib ra t ions of all s y m m e t r y types. We t r i ed to ca lcu la te the f r equenc ie s of the v ib ra t ions of py rene , u s i n g the i n t e r ac t i on coeff ic ients for the naphthale.ne mo lecu l e , obtained by Kra inov [3] as zero th approxi mat ion . In this case , however , we encounte red diff icu l t ies a s soc ia t ed with the ambigu i ty of the a s s i g n m e n t of the s t r u c t u r a l e l emen t s of the condensed r ings to the co r r e spond ing e l emen t s of the naphthalene mo l e cule . The r e su l t i ng ambigu i ty in some of the e l emen t s of the force cons tant o r i n t e r ac t i on coeff ic ient m a t r i c e s should be e l imina ted by se l ec t ion of the opt imal v e r s ion. Unfor tunate ly , the so lu t ion of d i f ferent v e r s i o n s of the s e c u l a r equat ions did not give sa t i s f ac to ry r e st i l ts . It was thus i m p o s s i b l e to put forward even erap i r i ea l ru les for the t r a n s f e r a b i l i t y of i n t e r ac t i on coeff ic ients . Under these condi t ions , it was na tu ra l to t ry to obt a in the s t r e t ch ing force cons tan ts of py rene , pe ry lene , and coronene by means of quan tum-chemica l methods . We shal l subsequent ly follow the method proposed by Coulson and Longuet-Higgins [4], appl icable for the ca lcu la t ion of the force cons tan ts of complex conjugated s y s t e m s . The total ene rgy of the e lec t rons E of the molecule is expressed as the sum of the ene rg ie s of the 7re l ec t rons E~ and the ~ e l e c t r o n s Ecr , f rom which i t i s poss ib le to obta in an addit ive r e p r e s e n t a t i o n of the force cons tan ts

The crystal structure of 11,12-dihydroxydrim-8(9)-en-7-one was determined by X-ray diffraction. The unit cell parameters are a = 7.534(3), b = 12.192(5), c = 8.067(4) A, β = 98.01(3) A, space group P21, and Z = 2 for C15H24O3. The structure was solved by direct methods and refined in the anisotropic approximation to R = 0.051 and R w = 0.113. The intramolecular O-H⋯O hydrogen bond [2.892(6) A] between the hydroxy groups closes an additional seven-membered H-ring in the molecule. In the crystal, the intermolecular O-H⋯O hydrogen bond [2.857(4) A] between the hydroxyl group and the carbonyl oxygen atom links the molecules related by the translation along the c-axis to form infinite chains.