Optimization of quantum cascade laser operation by geometric design of cascade active band in open and closed models

Using the effective mass and rectangular potential approximations, the theory of electron dynamic conductivity is developed for the plane multilayer resonance tunnel structure placed into a constant electric field within the model of open nanosystem, and oscillator forces of quantum transitions within the model of closed nanosystem. For the experimentally produced quantum cascade laser with four-barrier active band of separate cascade, it is proven that just the theory of dynamic conductivity in the model of open cascade most adequately describes the radiation of high frequency electromagnetic field while the electrons transport through the resonance tunnel structure driven by a constant electric field.Comment: 10 pages, 2 figure

Nematicidal activity of aqueous tinctures of medicinal plants against larvae of the nematodes Strongyloides papillosus and Haemonchus contortus

The study focuses on in vitro effect of aqueous tinctures of 48 species of herbaceous, shrub and tree plants on the first-third stage larvae of Strongyloides papillosus (Wedl, 1856) and third-stage larvae of Haemonchus contortus (Rudolphi, 1803) Cobb, 1898. The highest level of the effect was exerted by 3% aqueous tinctures of Wisteria sinensis (Sims) DC., Ailanthus altissima (Mill.) Swingle, Laburnum anagyroides Medik., Quercus petraea subsp. iberica (Steven ex M. Bieb.) Krassiln., Ginkgo biloba L., Colchicum autumnale L., Aristolochia manshuriensis Kom., Celastrus scandens L., Securigera varia (L.) Lassen, Magnolia kobus DC. Over 90% of the first and second non-invasive stage larvae of S. papillosus died at contact with these tinctures. The lowest parameters of LD50 were seen for L. anagyroides, Juniperus sabina L., C. scandens, M. kobus, A. manshuriensis, Wisteria sinensis (Sims) DC. and Securigera varia (L.) Lassen. Invasive larvae of S. papillosus and H. contortus were resistant to the effect of all the 48 surveyed species of plants. Third-stage larvae of H. contortus remained vital when exposed for 24 h to all the studied concentrations up to 3% aqueous tincture of plants. The results of the experiments and also the analysis of the literature indicate the necessity to continue the survey on nematocidial activity of aqueous tinctures and alcveshol extracts of plants

Синтез та деякі перетворення 5-ізоксазолілсульфонілхлоридів

The effect of the structure of 5-(benzylthio)isoxazoles on selectivity of the synthesis of 5-(chlorosulfonyl)isoxazoles has been determined. The chemical behavior in relation to amines has been described.Aim. To develop the methods for the synthesis of 5-(chlorosulfonyl)- isoxazoles and 4-chloro-5-(chlorosulfonyl)isoxazoles as promising reagents for construction of prospective bioactive compounds.Results and discussion. The number of 5-(benzylthio)isoxazoles was obtained by cyclocondensation of N-hydroxyimidoyl chlorides or 2-chloro-2-(hydroxyimino) acetates with benzylethynylsulfide. Their oxidative chlorination with gaseous chlorine led to formation of the mixture of isoxazole-5-sulfonyl chlorides and 4-chloroisoxazole-5-sulfonyl chlorides. The ratio between these products in the mixture depended on the nature of the substitution group in position 3 of the isoxazole ring. For the synthesis of 4-chloro-5-(chlorosulfonyl)isoxazoles with acceptable yields the approach of an advance chlorination of 5-benzylthioisoxazoles by N-chlorosuccinimide with further oxidative chlorination was used.Experimental part. The synthesis of the starting and target compounds was performed in classic preparative conditions; flesh-chromatography; elemental analysis; LCMS; 1H and 13C NMR-spectroscopy were used.Conclusions. The reaction of oxidative chlorination of 5-(benzylthio)-3-isoxazoles has been studied. The synthetic approach for the previously unknown representatives of isoxazole-5-sulfonylchlorides has been developed.Определено влияние структуры 5-бензилтиоизоксазолов на селективность образования 5-изоксазолилсульфонилхлоридов и выявлено химическое поведение последних по отношению к аминам.Цель  работы – создание методов синтеза 5-изоксазолил- и 4-хлор-5-изоксазолилсульфонилхлоридов как перспективных реагентов для конструирования потенциально биоактивных веществ.Результаты и их обсуждение. Циклоконденсацией N-гидроксиимидоилхлоридов или 2-хлоро-2-(гидроксиимино)ацетатов из бензилтиоацетиленом синтезировано ряд 5-бензилтиоизоксазолов. Их окислительное хлорирование приводит к образованию смеси 5-изоксазолилсульфонилхлоридов и 4-хлор-5-изоксазолилсульфонилхлоридов, соотношение между которыми зависит от характера заместителей в положении 3 изоксазольного цикла. Для синтеза 4-хлор-5-изоксазолилсульфонилхлоридов с удовлетворительными выходами использован вариант предварительного хлорирования ядра 5-бензилтиоизоксазолов N-хлорсукцинимидом с дальнейшим окислительным хлорированием.Экспериментальная часть. Синтез исходных и целевых соединений в классических препаративных условиях; методы флеш-хроматографии, элементного анализа, хроматомасс-спектрометрии, ЯМР 1Н и 13С-спектроскопии. Выводы. Исследована реакция окислительного хлорирования 5-бензилтиоизоксазолов и разработан синтетический подход к ранее неизвестным представителям 5-изоксазолилсульфонилхлоридов.Встановлено вплив структури 5-бензилтіоізоксазолів на селективність утворення 5-ізоксазолілсульфонілхлоридів та з’ясована хімічна поведінка останніх по відношенню до амінів.Мета роботи – створення методів синтезу 5-ізоксазоліл- та 4-хлоро-5-ізоксазолілсульфонілхлоридів як перспективних реагентів для конструювання потенційно біоактивних речовин.Результати та їх обговорення. Циклоконденсацією N-гідроксіімідоїлхлоридів або 2-хлоро-2-(гідроксііміно)ацетатів із бензилтіоацетиленом синтезовано низку 5-бензилтіоізоксазолів. Їх окиснювальне хлорування приводить до утворення суміші 5-ізоксазолілсульфонілхлоридів та 4-хлоро-5-ізоксазолілсульфонілхлоридів, співвідношення між якими залежить від характеру замісників у положенні 3 ізоксазольного циклу. Для синтезу 4-хлоро-5-ізоксазолілсульфонілхлоридів із задовільними виходами використано варіант попереднього хлорування ядра 5-бензилтіоізоксазолів N-хлоросукцинімідом із подальшим окиснювальним хлоруванням.Експериментальна частина. Синтез вихідних та цільових сполук у класичних препаративних умовах; методи флеш-хроматографії, елементного аналізу, хроматомас-спектрометрії, ЯМР 1Н та 13С-спектроскопії.Висновки. Досліджена реакція окиснювального хлорування 5-бензилтіоізоксазолів та розроблено синтетичний підхід до раніше невідомих представників 5-ізоксазолілсульфонілхлоридів

A major cellular substrate for protein kinases, annexin II, is a DNA-binding protein

AbstractWe have screened a human cDNA expression library in λgt11 for clones encoding Alu-binding proteins using direct binding of labeled Alu DNA to recombinant phage lysates fixed on a membrane, and isolated a clone 98% identical in sequence to the well-known substrate of protein kinases, annexin II, which was suggested earlier to play a role in transduction of mitogenic signals and DNA replication. A diagnostic property of annexins is their binding to phospholipids in the presence of calcium ions, and we have found that the interaction of proteins of human nuclear extracts with Alu subsequences is suppressed by Ca/phosphatidylserine liposomes, suggesting overlapping of Ca/phospholipid- and DNA-binding domains in annexin II

Singular reduction modules of differential equations

The notion of singular reduction modules, i.e., of singular modules of nonclassical (conditional) symmetry, of differential equations is introduced. It is shown that the derivation of nonclassical symmetries for differential equations can be improved by an in-depth prior study of the associated singular modules of vector fields. The form of differential functions and differential equations possessing parameterized families of singular modules is described up to point transformations. Singular cases of finding reduction modules are related to lowering the order of the corresponding reduced equations. As examples, singular reduction modules of evolution equations and second-order quasi-linear equations are studied. Reductions of differential equations to algebraic equations and to first-order ordinary differential equations are considered in detail within the framework proposed and are related to previous no-go results on nonclassical symmetries.Comment: 38 pages, advanced version. Extension of results of arXiv:0808.3577 to the case of a greater number of independent variable

Group analysis and exact solutions of a class of variable coefficient nonlinear telegraph equations

A complete group classification of a class of variable coefficient (1+1)-dimensional telegraph equations $f(x)u_{tt}=(H(u)u_x)_x+K(u)u_x$, is given, by using a compatibility method and additional equivalence transformations. A number of new interesting nonlinear invariant models which have non-trivial invariance algebras are obtained. Furthermore, the possible additional equivalence transformations between equations from the class under consideration are investigated. Exact solutions of special forms of these equations are also constructed via classical Lie method and generalized conditional transformations. Local conservation laws with characteristics of order 0 of the class under consideration are classified with respect to the group of equivalence transformations.Comment: 23 page