Search

The structural characteristics typical of highly and moderately effective antagonists of BLT1 and BLT2 receptors were identified and the extents of their influences on the target property were evaluated. Two models for predicting inhibitory activity were constructed for series of sulfur-, nitrogen- and oxygen-containing heterocyclic compounds with significant prognostic levels of greater than 80% using two methods based on sample recognition theory. These structural patterns can be used for virtual screening of potential drugs for antiallergic activity associated with blockade of leukotriene LTB4-sensitive BLT1 and BLT2 receptors.

This article addresses mathematical modeling of the reaction of inhibited organic compounds oxidation. It was proposed to solve the inverse problems of chemical kinetics by using the index method of constrained global minimization of the deviation between the calculated and experimental data. This approach allows us to use more complete information about the chemical process which, in its turn, reduces the range of possible solutions, narrows down the domain of uncertainty, and improves the quality of mathematical model of chemical reactions. The index method was applied to solving inverse kinetic problem for the reaction of n-decane oxidation in the presence of a p-oxydiphenylamine/n-decyl alcohol inhibitory composition.

We designed an algorithm and software for inverse kinetic problem solving by conditional global minimization of the deviation of calculated data from experimental data. This approach allows use of more complete information on the process, which narrows the region of feasibility and increases the quality of mathematical simulation of chemical reactions. The algorithms designed were tested in the kinetic description of a complex liquid-phase chain reaction, specifically, the oxidation of n-decane in the presence of an inhibiting composition, viz., para-oxydiphenylamine + n-decanol.

The dependence of the properties of finite two-component Fermi systems containing two types of oppositely charged particles on the ratio of their masses has been studied. A theoretical model for the quantum-mechanical description of a system containing a finite number of pairs of particles has been proposed on the basis of the Hartree-Fock approximation and the random-phase approximation with exchange. A method that makes it possible to exclude the motion of the center of mass of the system from the spectrum of excited states has been developed in the random-phase approximation with exchange. This method has been used to calculate the binding energies and static dipole polarizabilities of systems containing 8, 20, and 40 pairs of oppositely charged particles at various ratios of their masses.

A new software package is suggested for solving the inverse kinetic problem for inhibited oxidation reactions of organic compounds. The software has been developed using inhibited n-decane oxidation as the model reaction.

A new method for the detection and identification of nucleophiles based on a luminescence turn-on mechanism is presented. Electrophilic luminophores bearing a heavy atom as a leaving group are applied to the detection and identification of nucleophiles using a PET-like method. The presence of the heavy atom on the electrophilic luminophore induces heavy atom luminescence quenching through spin–orbit coupling and increased S1 → T1 intersystem crossing efficiency. Upon reaction with a nucleophile the heavy atom is replaced by the nucleophile and the luminescence of the luminophore is regained. The potential of this approach is demonstrated by detecting and identifying various nucleophiles using 9-anthrylmethyl 2-iodoacetate and N-(9-anthrylmethyl)-2-iodo-acetamide. The two poorly luminescent systems turn-on upon reacting with nucleophiles both in solutions and in the solid-state (films).

The antioxidant properties of 2,4-diphenyl-7,8-benzo-5,6-dihydro(4H)selenochromene, some of its chlorine-containing derivatives, and selected chromilium salts based on these derivatives have been investigated using the initiated oxidation of 1,4-dioxane as a model reaction. The antioxidant activity of these compounds is quantitatively characterized by the apparent inhibition rate constant fk7.

Structural features characteristic of high-, medium-, and low-efficiency inhibitors of 5-lipoxygenase (5-LOG) catalytic activity were established. The degree of their influence on the inhibition efficiency was assessed. Two models (M1 and M2) were constructed for the prediction and recognition of the efficiency intervals of 5-LOG inhibitors. The confidence level of activity prediction for M1 and M2 reached 90 and 70%, respectively. The revealed structural features could be used for constructing highly selective inhibitors of 5-LOG catalytic activity.

The kinetics of the reactions of 5-hydroxy-6-methyluracil and 6-methyluracil with hydrogen peroxide in aqueous solutions has been investigated. The reactions proceed via two competitive mechanisms, namely, free-radical and nonradical ones. The iron ions present in water as impurities make possible the free-radical mechanism.

Antioxidant properties of technical-grade mixtures containing 4, 6-methyl-substituted derivatives of isobornylphenol were studied. The antioxidant activity of samples was characterized by the inhibition rate constant kIn. The effect of isobornylphenol on the kinetics of inhibition of the thermooxidative dehydrochlorination of poly(vinyl chloride) plasticized with dioctyl phthalate was examined.

Sequence-independent or “click” chemistry is applied for the preparation of a series of novel and structurally similar π-conjugated oligomers. The new oligomers are prepared using Wittig–Horner chemistry from bifunctional building blocks that can be interconnected to one another at any desired sequence. The bifunctional building blocks consist of aromatic skeletons with acetal protected aldehyde groups on one side and a phosphonic acid diethyl ester group para to the aldehyde functionality. The first step in the arylenevinylene formation is a Wittig–Horner coupling of a functionalized aldehyde with the methyl phosphonate ester ylide of a bifunctional monomer. A stepwise protection–deprotection process is applied for the preparation of structurally similar π-conjugated oligo-phenylene vinylenes. New di-, tri-, penta-, and hepta-phenylenevinylenes are prepared and characterized. Selected penta-arylenevinylenes are incorporated as the semiconductor channel in organic field-effect transistors.

A structure–antiarrhythmic activity relationship has been investigated using a chloroform model of arrhythmia in rats. A mathematical model capable of predicting and recognizing antiarrhythmic activity with 84% reliability is formulated. Optimization of the molecular design of lidocaine and procainamide, which have weak antiarrhythmic activity, has resulted in modeling and predicting 51 much more effective antiarrhythmic compounds that can be synthesized for further testing.

The transport of polarized electrons in photocathodes based on highly strained semiconductor superlattices is studied experimentally and theoretically. In the experiments, the electron emission from the photocathode excited by a femtosecond laser pulse is studied by time-resolved measurements. The response time and the spin relaxation time are experimentally determined. The photoresponse of the photocathodes is calculated, and the results are correlated with the experimental data. A conclusion regarding the partial localization of photoelectrons in the superlattice is drawn.

Structural signatures characteristic of high-, medium-, and low-efficiency inhibitors of the catalytic activity of 15-lipoxygenase (15-LOG) have been revealed using the SARD-21 (Structure Activity Relationship & Design) computer system. The degree of their influence on the efficiency of the inhibiting activity was estimated. Based on these data, two models are constructed for predicting the interval of LOG-inhibiting activity of various sulfur-, nitrogen-, and oxygen-containing heterocyclic compounds with an 80% prediction accuracy level for the two recognition methods. The revealed structural features can be used to construct highly selective inhibitors of 15-LOG catalytic activity.

Electro-physical parameters of super-thin basalt fiber (STBF) from Armenian basalt rocks are measured before and after hydrochloric acid treatment. It is shown that specific resistance and dielectric parameters of super-thin basalt fiber change essentially after hydrochloric acid treatment. The temperature dependence of these parameters was studied too. The probable cause of the change is an increase in the total amount of pores and modification of the share of pores of various sizes in STBF, followed by an increase of absorption of water molecules from the ambient medium. The results (in both alternating and direct electric fields) are interpreted within the framework of the dipole-relaxation mechanism of the polarization of water molecules in STBF pores.

The antioxidant properties of conjugates of betulonic and betulinic acids with amido derivatives of the acid Trolox were studied for initiated 1,4-dioxane oxidation as a model reaction. The antioxidant activity of the compounds was characterized in terms of the apparent inhibition rate constant fk In.

The antiradical properties of a number of uracil derivatives are studied in initiated 1,4-dioxane oxidation as a model reaction. The antioxidant activity of the uracil derivatives as inhibitors is estimated. The antiradical activity of the compounds is quantitatively characterized in terms of the effective rate constant of inhibition, fkIn.

The influence of hydrochloric or sulphuric acid treatment on the electro-physical properties of superthin basalt fiber (STBF) made from Armenian basalt rocks was studied. Specific electric resistance for direct and alternating currents, dielectric parameters of e, and e,, were measured. It is shown that specific resistance and dielectric parameters of super-thin basalt fiber change essentially after hydrochloric or sulphuric acid treatment. The temperature dependences of these parameters were studied, too, and their non–monotonic behavior was observed. The probable variation of mentioned STBF parameters is explained by different water absorption capacity of pores as a result of acid treatment.

Alkylating agents are reactive, often simple, molecules that are frequently used in diverse fields such as medicine, agriculture, and organic synthesis. For over a century, some highly reactive alkylating agents are also being used as blister chemical warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and often simple structure. Here we report on a new approach for the detection and identification of such alkylating agents using a simple luminescence based array sensor that mimics the olfactory system. In order to demonstrate the potential of the approach, seven π-conjugated oligomers and polymers bearing nucleophilic pyridine groups, 1-7, were adsorbed onto a solid support and exposed to vapors of alkylators 8-15. Applying principal component analysis to the alkylation induced color shift patterns of the seven-spot array results with a clear discrimination of the different alkylators. The comparison of the data obtained from the sensor array with known response patterns allows the clear identification of the specific alkylator. The spots are sensitive to minute concentrations of alkylators and since the detection is based on the formation of new covalent bonds these spots saturate, within seconds even at about 50 ppb. Copyright © 2010 John Wiley & Sons, Ltd.

The antioxidant properties of 20-hydroxyecdysone and its conjugates with (6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)acetaldehyde are reported for initiated 1,4-dioxane oxidation as a model reaction. The antioxidant activity of these compounds is characterized in terms of the effective rate constant of inhibition, fk In.

Using the SARD-21 (Structure Activity Relationship & Design) computer system, structural features of high- and low-effective antiarrhythmic agents have been recognized and the influence of these features on the antiarrhythmic properties has been evaluated. This information has been used for generation of the model to predict antiarrhythmic effectiveness of pharmaceutical preparations at the recognition level of 82% by means of two different approaches. The recognized structural parameters may be successfully used to design new highly effective antiarrhythmic drugs, and also to modify structures of the already-existing anti-arrhythmic drugs in order to increase the effectiveness of their antiarrhythmic action.

A classical approach to the description of angular momentum transfer between the Auger electron and photoelectron in post-collision interaction is worked out. The results of the classical approach coincide with the quantum mechanical ones at the photoionization threshold. Besides, the approach developed provides a description of angular momentum transfer beyond the photoionization threshold. In particular, it is suitable in the energy region of comparable velocities of two emitted electrons.

The antioxidant properties of morin, myricetin, fisetin, naringenin, and naringin were studied using the initiated oxidation of 1,4-dioxane as the model reaction. The antioxidant activity of these compounds was quantitatively characterized by the apparent rate constant of inhibition, fkin. Morin, myricetin, and fisetin are comparable with ionol in antioxidant efficiency.

Alkylating agents are simple and reactive molecules that are commonly used in many and diverse fields such as organic synthesis, medicine, and agriculture. Some highly reactive alkylating species are also being used as blister chemical-warfare agents. The detection and identification of alkylating agents is not a trivial issue because of their high reactivity and simple structure. Herein, we report on a new multispot luminescence-based approach to the detection and identification of alkylating agents. In order to demonstrate the potential of the approach, seven pi-conjugated oligomers and polymers bearing nucleophilic pyridine groups, 1-7, were adsorbed onto a solid support and exposed to vapors of alkylators 8-15. The alkylation-induced color-shift patterns of the seven-spot array allow clear discrimination of the different alkylators. The spots are sensitive to minute concentrations of alkylators and, because the detection is based on the formation of new covalent bonds, these spots saturate at about 50 ppb.

Resonance enhancement of the quantum yield of polarized electrons from photocathodes based on strained short-period semiconductor superlattices is studied. The superlattice is a constituent of a Fabry-Perot optical cavity formed by the outer surface of the photocathode and the distributed Bragg reflector. An increase in the quantum yield by an order of magnitude is observed in the wavelength region corresponding to the maximum degree of polarization of photoemission.

The rind of muskmelon (Cucumis melo L. var. reticulatus) fruits contains a network of suberized periderm tissue, referred as the 'net', which originates in response to cracking of the fruit surface during its enlargement. Shallow cuts were made on the surface of melons to mimic naturally occurring cracking and induce net-like periderm development. Histological analysis of wounded fruits of the climacteric netted variety Krimka, and of two smooth melon varieties: the climacteric Momordica and the non-climacteric Tamdew, indicated that smooth melon varieties can undergo netting when their rind is fissured. Furthermore, the results implied that the climacteric character is not essential for net-tissue development, even though most netted varieties are climacteric. The involvement of ethylene in net- like periderm development was studied by analyzing the expression pattern of the ethylene-biosynthesis genes 1-aminocyclopropane-1-carboxylate synthase 1 and 1-aminocyclopropane-1-carboxylate oxidase 1 following wounding and during periderm development, and by applying the ethylene-generating chemical, Ethrel, as a lanolin paste, on the fresh cuts. Results suggested ethylene involvement in periderm initiation, but continuous exposure may interfere with further tissue development and organization. General implications of the current study on periderm development are further discussed.

The kinetics of 1,4-dioxane oxidation initiated by azodiisobutyronitrile in the temperature range from 323 to 353 K are studied from the rate of oxygen absorption. The oxidation proceeds in the regime of a nonbranched chain reaction with quadratic-law chain termination. The apparent rate constants (fk7) of 1,4-dioxane oxidation inhibition by 2,6-ditert-butyl-4-methylphenol and quercitin are measured. Quercitin is not inferior to ionol in inhibition efficiency.

Antioxidant properties of caffeic, ferulic, vanillic, and 4-hydroxybenzoic acids isolated from Larix sibirica Ledeb. bark were studied using model radical-chain reactions for oxidation of propan-2-ol and 1,4-dioxane under kinetic control. Quantitative characteristics of the antioxidant activities were determined as effective rate constants fkIn for oxidation chain termination of the phenolcarboxylic acids. It was found that caffeic acid had the highest antioxidant activity among the investigated natural compounds.

Using the computer system SARD-21 (Structure Activity Relationship & Design) structural features typical for the high-and low-effective nonsteroidal anti-inflammatory drugs (NSAIDs) have been recognized and the influence of these features on the anti-inflammatory properties have been evaluated. This information has been used for generation of the model for prediction of anti-inflammatory effectiveness of pharmaceutical preparations with 76% and 81% levels of recognition by two methods. The recognized structural parameters may be successfully used for creation of new highly effective NSAIDs, and also for modification of structures of known NSAIDs for the increase of effectiveness of their anti-inflammatory action.

We consider the double ionization (DI) of a helium atom by fast protons and study the role of electron correlations in this process. We develop a quantum-mechanical approach that takes into account the interaction of the emitted electrons in continuum and the dynamical charge screening of the ejected particles, which depends on their ejection kinematics. The interaction of the emitted electrons between themselves and with the core is described in the model of approximate 3C functions, while the dynamical charge screening is described by introducing effective charges of the emitted electrons and the ion core, which are determined by the particle momenta. The derived closed analytical expressions for the differential ionization cross sections have been applied to the case of a coplanar particle ejection geometry at various momenta q transferred to the atom. Analysis of our calculations has shown that the developed model describes adequately the available experimental data. Including the dynamical charge screening has a significant effect on the DI cross section and improves considerably the agreement between theory and experiment.

A model for predicting cyclooxygenase (COX-1 and COX-2) selectivity of chemical compounds is developed using a computer Structure-Activity Relationship & Design (SARD-21) system. Structural features characteristic of nonsteroidal antiinflammatory drugs (NSAIDs) selectively acting on each of the COX isoforms are established for the first time. Validation of this model on a test set of 20 structures showed recognition at the level of 85%.

Using the GUSAR program, structure-activity relationships on inhibition of cyclooxygenase-2 (COX-2) catalytic activity were quantitatively analyzed for twenty-six derivatives of 4,5,6,7-tetrahydro-2H-isoindole, 2,3-dihydro-1H-pyrrolyzine, and benzothiophene in the concentration range of 0.6–700 nmol/liter IC50 values. Six statistically significant consensus QSAR models for prediction of IC50 values were designed based on MNA- and QNA-descriptors and their combinations. These models demonstrated high accuracy in the prediction of IC50 values for structures of both training and test sets. Structural fragments of the COX-2 inhibitors capable of strengthening or weakening the desired property were determined using the same program. This information can be taken into consideration on molecular design of new COX-2 inhibitors. It was shown that in most cases, the influence of structural fragments on the inhibitory activity of the studied compounds revealed with the GUSAR program coincided with the results of expert evaluation of their effects based on known experimental data, and this can be used for optimization of structures to change the value of their biological activity.

Photoemission of polarized electrons from heterostructures based on InAlGaAs/GaAs superlattices with minimum conduction-band offsets is investigated. The comparison of the excitation energy dependence of the photoemission polarization degree with the calculated spectra make it possible to determine the polarization losses at different stages of the photoemission. A maximum polarization of P = 91% and a quantum yield of 0.14% are close to the best results obtained for photocathodes on the basis of strained semiconductor superlattices.

A mathematical model for prediction of antioxidant activity (AOA) with a recognition level of ∼90% was developed using the SARD-21 computer system. Based on this model, structural modification of ionol and 5-hydroxy-6-methyluracil was carried out. A set including 32 potential antioxidants was generated. The interval levels of toxicity were theoretically predicted and the effect of structural fragments on the toxic properties of the most efficient potential antioxidants was analyzed. Structural attributes characteristic of highly efficient, low-toxicity antioxidants were revealed for the first time. Based on complex analyses of the AOA and toxicity, thirteen structures of potentially efficient low-toxicity antioxidants were proposed.

A new approach to the resonance photoabsorption of metal clusters in strong laser fields is introduced. The method is based on the separation of the center of mass and the intrinsic motion of delocalized valence electrons. We calculate the excitation spectra of sodium clusters beyond the standard linear response theory, including highly excited states with more than one plasmon. We study the non-linear effects in photoabsorption of small sodium cluster in strong laser field. The degree of anharmonicity of dipole plasmon excitations is examined. We analyze the ionization of sodium clusters by intense laser pulse with photon energy close to the surface plasmon resonance. The proposed model describes the resonance channel of cluster ionization via excitation of double-plasmon collective electron state that subsequently decays by a single electron emission. The autoionization decay rate of two-plasmon excited state together with the energy and angular distributions of outgoing electrons is obtained for positively charged sodium clusters. Parameters of the laser pulse which are favorable for the resonant multi-plasmon ionization are analyzed.

The antioxidant [AO] properties of the ethylacetate extract of Larix sibirica bark and the flavonoids quercetin and dihydroquercetin found in it were studied using a model radical-chain oxidation of propan-2-ol in the kinetic regime. The quantitative characteristics of their AO activity were determined as effective rate constants fkln. It was found that dihydroquercetin had the highest AO activity among the studied natural compounds.

Reciprocal influence of antioxidizing and detergent-dispersive components of batch additives have been studied. Oligomers of piperylene and isobutylene functionalized by element sulfur and phenols in combination with succinimide have been chosen as the object of research. Constants of inhibition rates have been determined for oligomer antioxidizing agents. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1842–1846, 2007

The kinetics of the reactions of ozone with 12 substituted olefins in aqueous solutions at 293 K are studied by the stopped-flow method. Second-order rate constants are determined for these reactions. The dependence of the reactivity of olefins in H2O on their structure can be described by the Taft equation.

Attenuation of light in light guides is a well understood phenomenon from the point of view of the basic underlying physics. Particularly in the case of light guides having a macroscopic cross section, ray trace modeling captures all of the key physics and makes it possible to accurately predict the decay of radiant flux as a function of length in the guide. Unfortunately, in typical applications in the field of illuminating engineering, such calculations are prohibitively difficult for two primary reasons. First, the precise bi-directional reflectance distribution function for the internal surfaces may not be readily available. Second, the precise angular distribution of luminous intensity, as a function of position on the input aperture, may also not be easily quantified. This paper presents a surprisingly simple and accurate general model for describing the flux attenuation with distance in a general light guide. The model has only two free parameters, and therefore measurement of decay at just...

The optical response of simple metal clusters to strong laser fields should bear evidence of possible anharmonicities of dipole surface plasmon collective excitations. We present a theoretical method that allows one to calculate the excitation spectrum of sodium clusters beyond the linear response theory, including highly excited states with more than one plasmon. We make use of a coordinate transformation to separate center of mass (c.m.) and intrinsic motion of delocalized electrons. The coupling between c.m. motion and intrinsic excitations leads to some anharmonicity of the giant dipole oscillations. We calculate the photoabsorption spectrum of sodium clusters for increasing laser intensities and find sizeable anharmonic effects.

Theoretical study of the ionization of sodium clusters by an intense laser pulse with a photon energy close to the surface plasmon resonance is presented. The proposed model describes the resonance channel of cluster ionization via excitation of a multi-plasmon collective electron state that can subsequently decay through a single electron emission. The method of separation of the centre of mass coordinate from other electronic degrees of freedom has been employed to take into account the highly excited electronic states. The autoionization decay rate of the multi-plasmon excited state together with the energy and angular distributions of outgoing electrons has been obtained.

Today's specialists have decided that in the future business should become less hierarchical and more flexible and mobile. According to the latest studies, the best manager of the new generation should know how to listen well to his or her employees, to motivate and encourage them: "One group has huge advantages in realizing the new approach—namely, women" [1, p. 194]. In our opinion, Henry Mintzberg is correct when he writes: "The time is long since past when women succeeded by learning to play according to men's rules. Today business needs something that women can give it" [2]. High-class managers are the basis of any company's success. It is important to identify the special traits that promote success and identify managers of women's business and junior executives in Russian and joint ventures. Given the surplus of qualified manpower in the labor market, women have the most trouble finding work. The involvement of criminal organizations in handling security and enterprise finances make it even more di...

The correlation function between two emitted electrons has been calculated as a function of their momentum difference for double ionization of 1s2s excited He atoms by fast ion impact. A simple quantum mechanical approach is developed to take into account the dynamics of two-electron ejection as well as the effects of electron exchange and correlated electron motion in the final state. A clear difference between the correlation functions of the excited and ground state targets is reported.

New potential inhibitors of 5-lipoxygenase (5-LOX) based on the structure of 2-(3-benzoylphenyl)propanoic acid (an active component of the nonsteroidal antiinflammatory drug Ketoprofen) were designed using the SARD-21 program. The docking of these compounds in the active site of 5-LOX suggested that seven compounds can interact with this enzyme. Two of them can also be dual inhibitors of 5-LOX and two isoforms of cyclooxygenase.

We study electron-electron correlation effects in double ionization of He and Ne by 3.6 MeV/amu Au53+ impact by analysing the correlation function for back-to-back emission of electrons with equal energy. For this particular emission pattern we find the correlation function to be sensitive to the target while without selection of this pattern no significant dependence on the initial state is observed. Therefore, this method may open the possibility to sensitively map correlated many-electron bound states.