Alkyl 2-amino-5,6-dialkyl-3-cyanopyridine-4-carboxylates in reactions with electrophilic reagents

In reaction of alkyl 2-amino-5,6-dialkyl-3-cyanopyridine-4-carboxylates with isocyanates formed unstable ureas, and with nitrous acid at 60–70°C alkyl 5,6-dialkyl-2-oxo-1,2-dihydro-4-pyidinecarboxylates were obtained. It was shown for the latter that their reactions with organic acids and amides occurred at the cyano group, and the alkaline hydrolysis involved the ester group.     

New criteria for uniform approximability by harmonic functions on compact sets in ℝ<Superscript>2</Superscript>

New uniform approximability criteria formulated in terms of logarithmic capacity are obtained for approximations by harmonic functions on compact sets in ?². A relationship between these approximations and analogous approximations on compact sets in ?³ is established.     

Comparison of the Techniques for Multipactor Discharge Damping in Coupling Cells of CDS Accelerating Structure

In the CDS structure proposed to substitute the first cavity of the main part of the linac at the Institute for Nuclear Research of the Russian Academy of Sciences, the appearance of a multipactor discharge (MP) in coupling cells at the operating level of the accelerating field was detected. Earlier, an option for MP damping by alternating neighbor accelerating cell frequency detuning was considered. This option complicates the cavity section tuning. An option for MP removal by changes in the coupling cell geometry inducing the destruction of phase conditions of the electron cloud resonance motion was studied. The analytical estimation and results of numerical simulations are presented. In conditions of the first cavity of the INR linac, the options considered were compared with respect to the efficiency of MP damping and the enhanced resistivity to the increase of the secondary emission yield.

     

Synthesis of blood group Forssman pentasaccharide GalNAcα1-3GalNAcβ1-3Galα1-4Galβ1-4Glcβ–R

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Synthesis of GalNGcα1-3GalNAcα disaccharide and its interaction with human blood antibodies

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Analysis of the fiber length dependence of its strength by using the weakest-link approach 1. A family of weakest-link distribution functions

This paper presents a summary and further development of the ideas proposed in the previous papers of the authors, which were dedicated to investigating the fiber scale effect (strength-length relation). In the first part of the paper, some theoretical aspects of the problem are considered; in the second one, an application to the processing of test datasets is discussed. As distinct from our previous publications, two types of defects (“technological,” i.e., existing before loading, and load-dependent) and two types of influence of the number of defects on the fiber strength are considered; the probability of absence of defects is also taken into account. We consider a specimen as a sequence of n elements of the same length. It is supposed that there are defects in K of them, 0 ≤ K ≤ n. Two cases are considered: K is a random variable or a random process K (t). In the second case, the increase in K and the failure of a specimen is described as a Markov chain whose matrix of transition probabilities depends on the current value of the loading process, described as some (increasing to infinity) sequence {x₁, x₂, …, x_t,…}. Three versions of relationships between the specimen strength and the number of defective elements are considered for both the cases. Thus, six probability structures are introduced, and different versions of distribution functions and the corresponding models are considered. The methods for estimating the model parameters, the results obtained in processing glass, flax, carbon fiber, and carbon bundle datasets, as well as a comparison of different models, are presented in the second part of the paper. Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 5, pp. 685–696, September–October, 2008.     

Ozonolysis of Alkenes and Studies of Reactions of Polyfunctional Compounds: LXV. Ozonolysis of Perfluoro-1-octene in Freon-113

Ozonization of perfluoro-1-octene in Freon-113 yields the corresponding ozonide whose catalytic hydrogenation over Pd/C or hydride reduction leads to formation of perfluoroheptanoic acid; the reduction with lithium aluminum hydride gives 2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoro-1-heptanol. Ozonization of perfluoro-1-octene in Freon-113 containing excess (3 equiv) alcohol affords the corresponding perfluoroheptanoic acid ester.     

Identification and Biological Activity of Volatile Organic Compounds Isolated from Plants and Insects. III. Chromatography-Mass Spectrometry of Volatile Compounds of Aegopodium podagraria

Gas chromatography-mass spectrometry identified more than 20 volatile organic compounds isolated from leaves and flowers ofAegopodium podagrariaL.