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The information content of the parameters of a spectral voice source model in an automatic voice identity recognition problem is studied. For the voice parameters, the identity recognition error was 20.8%; using these parameters together with the pitch period reduced the error to 13.8%. Lastly, the combined use of the spectral model parameters with the pitch period and mel-frequency cepstral coefficients provided the highest accuracy (the recognition error was 1.2%). [ABSTRACT FROM AUTHOR]

2-Nitro-1H-benzo[f]chromenes reacted with alcohols to give a series of 3-alkoxy-2-nitro-2,3-dihy-dro-1H-benzo[f]chromenes as mixtures of cis and trans isomers. The reaction of 2-nitro-1H-benzo[f]chromenes with cyclic secondary amines and 3-amino-5,5-dimethylcyclohex-2-en-1-one displayed trans diastereoselec-tivity with the formation of Michael adducts with benzochroman structure. Conjugate addition of substituted anilines to the title chromenes afforded (2-hydroxynaphthalen-1-ylmethyl)-substituted β-nitroenamines. Nucleophilic dearomatization of 3-nitrobenzofurans by the action of primary aromatic amines involved aza- and retro-oxa-Michael reactions, which demonstrated a strong tendency of 3-nitrobenzofurans to undergo opening of the furan ring. [ABSTRACT FROM AUTHOR]

A new recombinant Aspergillus niger tannase (tannin acyl hydrolase) produced by the Penicillium verruculosum fungus has been studied. A strain with a high level of extracellular tannase (TAN2) secretion (80% of the total extracellular protein) was obtained by cloning the tan2 gene (PDB Acc. no: MT828303) into the recipient strain. The tannase enzyme preparation degraded tannins in black tea extracts. TAN2 was isolated in homogeneous form using chromatographic methods; the enzyme had a high activity with respect to gallotannin (53 U/mg) and less activity against propyl gallate (4.7 U/mg). Homogeneous TAN2 showed temperature and pH optima of 45°C and 3.5, respectively. At a temperature of 50°C, TAN2 retained above 80% of its activity for 3 h; at 60°C about 75% of its activity for 90 min was preserved; at 70°C, the enzyme was completely inactivated within 10 min. Tannase was characterized by a high tolerance to NaCl, the activity with respect to gallotannin exceeded 50% of the initial value in solutions with a salt concentration of up to 5 M. The tannase activity was stimulated by Ca2+, Mg2+, Zn2+, Mn2+, Cu2+, Cd2+, and Pb2+ by 3–64%, and inhibited by 4‒65% in the presence of Co2+, Fe3+ and Fe2+ ions. [ABSTRACT FROM AUTHOR]

A method for producing substituted 4H-1,3-benzoxazines and their fused derivatives bearing N,N-dimethylamino moiety in the position 2 of 4H-1,3-oxazine ring from phenolic and naphtholic Mannich bases, their iodomethylates or salicylic alcohols, and 1,1,3,3-tetramethylguanidine has been developed. This reaction is supposed to proceed via the generation of o-quinone methides followed by [4+2]-cycloaddition and elimination of dimethylamine. [ABSTRACT FROM AUTHOR]

A comparative study of microstructure parameters and mechanical property characteristics of consolidated Ni3Al samples formed by spark plasma sintering after a preliminary short-term mechanical activation and mixing in a mortar is carried out. It is found out that the grain size of the mechanically pre-activated material is several times smaller than that of the material sintered after mixing in a mortar. This feature is manifested in the differences in the values of microhardness and short-term strength. The annealing temperature effect on the structure parameters and mechanical properties of Ni3Al samples is revealed depending on the pretreatment. It is assumed that the formation of a high-defect structural state, characterized by fine grains combined with an increased level of microdistortions, during mechanical activation predetermines the strength properties of the material both after spark plasma sintering and after deformation and heat treatment. [ABSTRACT FROM AUTHOR]

Using precursors, prepared by a preliminary mechanical activation of the 3Ni–Al powder mixture in the energy-intensive ball mills with and without a subsequent addition of the TiC powder, Ni3Al and Ni3Al+TiC samples are consolidated by spark plasma sintering. By the methods of structure characterization and measurement of mechanical properties a comparative study of the influence of TiC is performed. After consolidation, no influence of the introduced particles on the intermetallic matrix structure parameters is found out. Under the synthesis conditions and during the subsequent high-temperature annealing, TiC does not interact with the intermetallic matrix. The presence of coarse-disperse TiC particles favors an additional embrittlement of the Ni3Al+TiC composite at room temperature, while at elevated temperatures a considerable increase in strength and plasticity is observed compared to pure Ni3Al. It is shown that an increase in the tension temperature gives rise to a change in the fracture mechanisms of the intermetallic matrix and coarsedisperse TiC particles. [ABSTRACT FROM AUTHOR]

The model of a channel that describes the transmission of information in communication systems with a single-user receiver based on order statistics is considered. The transmission of information through such a channel using a linear block code is studied. The aim of this paper is to find an upper bound on error probability for the case in which exhaustive search and a given decoding criterion are used. [ABSTRACT FROM AUTHOR]

In the paper, a description of the Grothendieck–Serre duality on an arithmetic surface by means of fixing a horizontal divisor is given and this description is applied to the generalization of theta-invariants. [ABSTRACT FROM AUTHOR]

We construct Lax pairs for linear Hamiltonian systems of differential equations. In particular, the Gröbner bases are used for computations. It is proved that the mappings in the construction of Lax pairs are Poisson. Under study are the various properties of first integrals of the system which are obtained from Lax pairs. [ABSTRACT FROM AUTHOR]

As a result of cloning of the inuA, inu1, aglC, and fopA genes encoding endoinulinase (endoINU), exoinulinase (exoINU), α-galactosidase C (AGLС) and sucrase (SUC), respectively, into the recipient strain Penicillium verruculosum B1-537 (ΔniaD), recombinant producer strains were obtained that are capable of producing target recombinant enzymes with a high yield (32‒50% of the total extracellular protein). Enzyme preparations of endoINU, exoINU, AGLC, and SUC were obtained and characterized. Using chromatographic methods, endoINU, exoINU, SUC, and AGLC with a molecular weights of 62, 56, 67, and 76 kDa, respectively, were isolated in a homogeneous form (according to polyacrylamide gel electrophoresis). The homogeneous endoINU had a high specific activity against Jerusalem artichoke inulin (56 U/mg). ExoINU was active towards inulin (17 U/mg), sucrose (850 U/mg), raffinose (41 U/mg), and stachyose (15 U/mg). SUC decomposed sucrose (10.5 U/mg), raffinose, and stachyose (3.8 and 1.4 U/mg, respectively). AGLC had raffinase and stachyase activities (31 U/mg and 30 U/mg, respectively), exhibited no activity towards sucrose, but had a high level of activity towards the synthetic substrate, p-nitrophenyl-α-D-galactoside (311 U/mg). The kinetic parameters (kcat and Km) of the hydrolysis of the corresponding substrates by homogeneous enzymes were determined. The temperature optimum was 50‒55°C for endoINU, 55‒65°C for exoINU, 65°C for AGLC, and 35°C for SUC. EndoINU, exoINU, AGLC and SUC exhibited its maximum activity at pH 6.5, 4.5, 4.5‒5.0, and 5.5‒6.0, respectively. The thermal stability of the enzymes was studied at different temperatures. EndoINU exhaustively hydrolyzed inulin with the formation of fructooligosaccharides with a degree of polymerization of 3‒8. ExoINU quantitatively converted inulin into glucose-fructose syrup (GFS) with a Glu : Fru ratio of 1 : 3, and sucrose into GFS with a Glu : Fru ratio of about 1 : 0.63 (SUC provided the same results in the sucrose hydrolysis). Soy galactooligosaccharides (raffinose and stachyose) were converted to sucrose and monosaccharides (glucose, galactose, and fructose) under the action of AGLC. The combined action of SUC, and AGLC resulted in a complete conversion of raffinose, stachyose and sucrose to monosaccharides. The same results were achieved using ExoINU. This enzyme can be considered promising for biotechnological applications due to its broad substrate specificity, which allows it be used both for the production of GFS from inulin and sucrose, and for the destruction of soybean galactooligosaccharides. [ABSTRACT FROM AUTHOR]

The condensation of trifluoroacetyl-substituted 4 H-chromenes and 1 H-benzo[ f]chromenes with 6-amino-1,3-dimethyluracil and 6-aminothiouracil afforded a number of pyrido[2,3-d]pyrimidine derivatives containing a 2-hydroxybenzyl or 2-hydroxynaphthalen-1-ylmethyl group in the 6-position as a result of cascade transformation initiated by Michael addition. [ABSTRACT FROM AUTHOR]

The reaction of o-(chloromethyl)phenols with enamino ketones afforded a series of 3-acyl- and 3-formyl-4 H-chromenes as a result of cascade transformation including [4 + 2]-cycloaddition of enamino ketone to o-quinone methide generated in situ and subsequent elimination of secondary amine. [ABSTRACT FROM AUTHOR]

We prove that the higher-dimensional Contou-Carrère symbol is invariant under the continuous automorphisms of algebras of iterated Laurent series over a ring. Applying this property, we obtain a new explicit formula for the higher-dimensional Contou-Carrère symbol. Unlike previously known formulas, this formula holds over an arbitrary ring, not necessarily a Q-algebra, and its derivation does not employ algebraic K-theory. [ABSTRACT FROM AUTHOR]

In the paper, Lax pairs for linear Hamiltonian systems of differential equations are found. Besides, first integrals of the system which are obtained from the Lax pairs are investigated. [ABSTRACT FROM AUTHOR]

The article presents a proof for theorem related to the automorphism group of the discrete Heisenberg group which is isomorphic to the group and mentions discrete Heisenberg group, automorphism group and structure theorem.

A preamplifier for comparators of precision low-power consumption analog-digital converters is presented. In order to lower the average consumption current of amplifier cascades, the capacitors, which fulfill the function of current sources during charging at the comparison stage, are used in them as the dynamic load. A correction circuit of the zero bias error for amplifiers of this type is developed. Modeling of the device using CMOS elements with a design rule of 0.35 μm from library XA035 of factory XFAB showed that the average current consumption at an operating frequency of 1 MHz is about 7 μA. [ABSTRACT FROM AUTHOR]

Methods for the production and analysis of cellulase and hemicellulase enzyme preparations of various compositions based on the Penicillium verruculosum carbohydrase complex and intended for the effective hydrolysis of different types of cellulose-containing materials (CCMs) have been developed. New recombinant strains of P. verruculosum producing multienzyme carbohydrase complexes with increased activities of cellulases (due to the expression of endo-β-1,4-glucanases I and IV and cellobiohydrolase II from Trichoderma reesei) and hemicellulases (due to the expression of endo-β-1,4-xylanases from P. canescens and T. reesei and endo-β-1,4-mannanase from T. reesei) were constructed. The hydrolytic efficiency of the enzyme preparations (EPs) produced by the new recombinant strains during continuous hydrolysis of three CCM types (milled aspen, depitched pine wood, and milled bagasse) was studied. It was shown that new EPs containing recombinant proteins and retaining their own basic cellulase complex are characterized by the highest hydrolytic ability, exceeding that of the EP based on the original P. verruculosum strain. The recombinant enzyme preparations were highly stable; the optimal pH and temperature values for cellulase, xylanase and mannanase activities were in the range of 3.5-5.5 and 50-80°C, respectively. [ABSTRACT FROM AUTHOR]

The article discusses the scientific method for the synthesis of 1,5-dihydro-2H-chromeno[2,3-d]pyrimidine-2,4(3H)-diones from o-benzoquionone methide precursors including quaternary ammonium salt, mannich base and hydroxybenzyl alcohols. The chemical reactions of methide precursors were out by refluxing an equimolar mixture of reagents into an acetic acid. It conclude that advantages for developing method for preparing 2H-chromeno[2,3-d]pyrimidinediones uses o-benzoquionone methide precursors.

We find an analytic expression for estimating error probability in a multiple access system that employs a signal-code construction based on q-ary codes, dynamically allocated frequency subranges, and a maximal energy receiver under the influence of “tracking” interference. [ABSTRACT FROM AUTHOR]

We consider a multiple-access system in which each user is given q out of Q available subchannels ( q ≪ Q). We investigate capacities of two channels emerging in the system under consideration in the case of single-user reception. These channels can be considered as modifications of the A-channel. In the first case we assume that a signal transmitted by a certain user is always registered by the receiver. Thus, activity of other users is the only obstacle to correct reception of information transmitted by a certain user in the multiple-access system. In the second case we assume that the output of each subchannel is inverted with probability p. Analytical expressions (both asymptotic and nonasymptotic) are derived and investigated. [ABSTRACT FROM AUTHOR]

5 a-Amino-5 aH,11 H-chromeno[2,3- b]chromene-11 a(12 H)-carbonitriles were synthesized from malono-nitrile and o-quinone methides, generated in situ by the thermolysis of phenolic Mannich bases in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene. It was also shown that this heterocyclic system can be obtained from 2-amino-4 H-chromene-3-carbonitriles and the aforementioned o-quinone methides. [ABSTRACT FROM AUTHOR]

The analysis of the effect of the parasitic capacitors on the split capacitor array digital-to analog converter for use in the successive approximation register analog-to-digital converter is presented. The Verilog-A model of the split capacitor array is developed based on the analysis. The advantages of using this model in the context of the top-down design methodology are considered. [ABSTRACT FROM AUTHOR]

3-Amino-1 H-benzo[ f]chromene-2-carbonitriles were synthesized by non-catalytic reaction from Mannich bases of the naphthalene series and malononitrile. Reactive 1-benzylidene(or methylidene)naphthalen-2(1 H)-ones were presumed as intermediate products. [ABSTRACT FROM AUTHOR]

Reaction of 8-hydroxy-7-piperidinomethylquinoline with pyridinium ylides gave 2-acyl-2,3-dihydro-furo[3,2-h]quinolines. The formation of a highly electrophilic quinoline type o-quinone methide is proposed as an intermediate. [ABSTRACT FROM AUTHOR]

We address the problem of constructing a multiple access system for a disjunctive vector channel, similar to a multiuser channel without intensity information as described in [1]. To solve the problem, a signal-code construction based on nonbinary codes is proposed. For the resulting multiple access system, a lower bound on the relative group rate is derived. The bound coincides asymptotically with an upper bound. [ABSTRACT FROM AUTHOR]

The previously unreported 14 H-naphtho[1',2':5,6][1,3]oxazino[3,2- a]benzimidazole heterocyclic system was synthesized by the condensation of 1-dimethylaminomethyl-2-naphthols and 2-methyl-sulfanylbenzimidazole. A highly reactive o-methylenequinone derivative of naphthalene is proposed as an intermediate in this reaction. [ABSTRACT FROM AUTHOR]

The article discusses the biological activity of cage compounds with a specific mention of adamantane derivatives, treatment of type II diabetes with saxagliptin, adamantylation, racemic 2-(adamantan-1-yl)-2-aminoacetic acid's synthesis from accessible adamantane and hydantoin, hydrolysis and results of the synthesis.

Serum levels of endostatin, placental growth factor (PlGF), and fibroblast growth factors-1 and -2 (FGF-1 and FGF-2) were measured in 58 patients with primary osteosarcomas before therapy and in 21 healthy subjects. The incidence of serum FGF-1 in bone tumors was 2.5 times higher than in healthy individuals (p=0.004); significant levels of FGF-2, PlGF, and endostatin were detected in all examined subjects. The mean serum level of endostatin in healthy individuals was significantly lower than in the total group of patients with bone tumors (p=0.005). The level of FGF-1 in osteosarcomas was significantly higher than in chondrosarcomas (pp=0.008) was detected in osteosarcoma. No relationships between the levels of FGF-1, FGF-2, PlGF, and endostatin were detected in healthy subjects and patients with primary tumors of the bones. Differences in 3-year overall survival values of patients with bone sarcomas with different initial serum levels of FGF-1 and endostatin were detected. [ABSTRACT FROM AUTHOR]

We investigate various new properties and examples of the two-dimensional and one-dimensional Krichever correspondence. [ABSTRACT FROM AUTHOR]

A brief review of modern surface geodetic methods used in monitoring projects ranging in size from several tens of meters to several kilometers is presented. Buildings and various engineering structures, as well as slide-prone types of natural entities, pulsating glaciers, etc. are classed among these entities. Use of digital three-dimensional models of observable entities, which are developed from results of laser scanning and/or a digital photogrammetric survey, is proposed. [ABSTRACT FROM AUTHOR]

The article discusses a study regarding the chemical reaction of the organic compound 2,4-Di-tert-butyl-6-[(dimethylamino)methyl]phenol with diazabicyclo[5.4.0]undec-7-ene. Topics include the confirmation of the structure of alkalation product by X-ray analysis, the involvement of the hydroxy group in intramolecular hydrogen bond with the imino nitrogen atom and the recrystallization of the compound from aqueous methanol to ethanol.

The article offers information on a study conducted by authors related to synthesis of naphtho-triazolo-oxazines heterocyclic system. It mentions that the synthesis was carried in the presence of potassium carbonate (K2CO3). It states that the infra-red (IR) spectra of compounds reveals absence of stretching vibration bands for oxygen-hydrogen (O-H) bond.

The article focuses on the synthesis of 9,11-diamino-12 H-benzo[5,6]-chromeno[2,3- b]pyridine-10-carbonitriles. The pseudo-three-component reaction apparently proceeds via generation of the o-quinone methide A from the Mannich base, followed by addition of malononitrile by a Michael reaction, intramolecular heterocyclization and condensation of enaminonitrile B formed with a second equivalent of malononitrile, which leads to construction of the pyridine ring.

A comparative study of the features of the structure and characteristics of the mechanical properties of the V–Cr–W–Zr alloy depending on the modes of thermomechanical treatment has been carried out. It has been established that, compared with the standard mode of thermomechanical treatment, the use of the modified mode leads to a more than twofold decrease in the average grain size. The influence of the temperature of homogenizing annealing on the grain sizes after thermomechanical treatment has been revealed. Such a transformation of the structural-phase state when using a modified mode of thermomechanical treatment contributes to an increase in the short-term strength by ≈12 and ≈21% at 20 and 800°C, respectively, against the background of a slight decrease in ductility. It has been established that, regardless of the processing mode, a viscous type of fracture is observed, and an increase in the tensile temperature is accompanied by a multiple increase in cell sizes. The analysis of the influence of dispersity of second phase particles on the effects of hardening by the Orowan mechanism has been carried out. [ABSTRACT FROM AUTHOR]

Using transmission electron microscopy, the features of the grain and defect structure of the V–4Ti–4Cr alloy after 16 acts of biaxial and triaxial pressing at room temperature are studied. The microstructure of the alloy after these treatments is a structural composite with the elements of fine-crystalline and submicrocrystalline states. The defect structure is characterized by a crystal lattice curvature from 10 to 30°/μm. It is established that biaxial pressing contributes to a more intensive grinding of the crystallites and a formation of an anisotropic microstructure. The dislocation-disclination mechanism and localization in the direction of maximum shear stresses are thought to be the main mechanisms of structural transformation under conditions of high-strength state, formed as a consequence of dispersion strengthening by the second phase particles. The role of local internal stresses and their gradients in the processes of crystal lattice fragmentation under conditions of severe plastic deformations is discussed. [ABSTRACT FROM AUTHOR]

The impact of the reset energy on the overall energy efficiency of an successive-approximation register (SAR) ADC is examined for some recently reported switching schemes. The reset energy can several times exceed the switching energy drawn from the reference during conversion. The simple method based on the optimal capacitor charging is proposed. By utilising of two-step switching during the reset phase, the total energy consumption of the DAC's capacitive matrix can be decreased by ~20%. [ABSTRACT FROM AUTHOR]

The impact of the reset energy on the overall energy efficiency of an successive‐approximation register (SAR) ADC is examined for some recently reported switching schemes. The reset energy can several times exceed the switching energy drawn from the reference during conversion. The simple method based on the optimal capacitor charging is proposed. By utilising of two‐step switching during the reset phase, the total energy consumption of the DAC's capacitive matrix can be decreased by ∼20%. [ABSTRACT FROM AUTHOR]

It was shown that the presence of cellobiohydrolase, β-glucosidase, endoglucanase, arabinoxylan-arabinofuranhydrolase, pectin lyase, and polygalacturonase is necessary for efficient hydrolysis of sugar beet pulp (SBP). Optimal multienzyme complexes consisting of the same enzymes and additional endoarabinase or exoarabinase, endogalactanase, β-xylosidase, endoxylanase, and/or α-arabinofuranosidase were determined. These components enabled the conversion of SBP based on a yield of total reducing sugars (RSs) of 61–68%, an arabinose yield of 94%, and a glucose yield of 63–79%. The optimal complex from dry multienzyme preparations (EP) of cellulases, hemicellulases, and pectinases, which are produced by the fungal strains Penicillium canescens, P. verruculosum, and Aspergillus foetidus, enabled SBP hydrolysis based on arabinose and glucose yields close to 100% at an initial SBP concentration of 100–250 g/L and an EP concentration of 5–10 mg protein/g SBP after 24–48 h of hydrolysis. [ABSTRACT FROM AUTHOR]

The article offers information on synthesis of tetrahydro-8 H-chromeno[3,2- h]quinolin-8-ones conducted by the authors. It states that the reaction of the Mannich base with the enamines 2a,b is a tandem process that includes formation of o-quinone methide from the Mannich base. It mentions that infra-red (IR) spectra of compounds 3a,b revealed absorption bands corresponding to the stretching of a carbonyl group.

The article offers information on the synthesis of triazolo benzoxazines and alkylation of 1H-azoles by salicyl alcohol. It states that this reaction is formed through the stage of formation of o-methylenequinone from salicyl alcohol. It is concluded that the alkylation of azoles by salicyl alcohol gives rise to the formation of phenols.

via reaction of uracil (I) with o-benzoquinone methide precursors [ABSTRACT FROM AUTHOR]

A new method for the synthesis of chromenochromenes (III) is developed based on the cycloaddition of o-quinone methides, generated in situ from phenolic Mannich bases (I), to 2-aminochromene-3-carbonitrile intermediates derived from Mannich bases (I) and malononitrile. [ABSTRACT FROM AUTHOR]

The article presents the chemical steps involved in the synthesis of 3-amino-1H-benzo[f]chromene-2-carbonitriles.

The effect of annealing temperature on the grain structure and microhardness values of the V–4Ti–4Cr alloy after thermomechanical treatment with rolling has been investigated. The specificity of the change in the texture of the V–4Ti–4Cr alloy with an increase in the annealing temperature was studied by x-ray diffraction analysis. Based on the EBSD analysis data, changes in the grain structure after annealing at different temperatures were revealed. The temperature intervals for the implementation of the main processes of relaxation and recrystallization of the alloy under study were revealed. The microband (layered) structural state formed after the rolling stage is characterized by a rolling texture of the {100}<110> type which is stable up to a temperature of 700°C at which partial recovery begins with relaxation of the most defective areas. At 800°C, primary recrystallization processes are activated, which at 900°C cover the entire volume of the material. An equilibrium structural state with no rolling texture is formed after annealing at 1000°C. Secondary recrystallization processes are activated at 1300°C. With an increase in the annealing temperature from 700 to 900°C, the microhardness decreases from 2.3 to 1.75 GPa. No nonequilibrium solid solutions of interstitial atoms were found in the entire annealing temperature range. [ABSTRACT FROM AUTHOR]

via reaction of γ-hydroxyquinoline derivatives (I) with in situ generated pyridinium ylides [ABSTRACT FROM AUTHOR]