Analogs of pyrimidine nucleosides

The UV absorption spectra of 5-substituted N¹-(tetrahydrofuran-2-yl)- and N¹-(2oxotetrahydrofuran-3-yl)uracils have been studied and their protolysis constants have been determined by the spectrophotometric method. A comparison is given with the spectra and pKa values of the corresponding N¹-methyl derivatives and ribosides and deoxyribosides.For part IV see [11].The work was carried out with analytical samples of compounds obtained by us previously [9–12].     

Solute transport through layered soil profiles: Zero and perfect travel time correlation models

In this paper the problem of solute transport through layered soil is modeled with a transfer function, representing the travel time to any depth in the soil as the sum of the travel times through the individual layers. The probability density function (pdf) of this travel time depends on the joint pdfs of the travel times through the individual layers, and hence on the correlation structure as well as the layer properties. Analytic expressions are derived for the flux and resident concentrations in layered soil for two limiting cases of correlation structure, for both convective-dispersive and stochastic-convective model representations of transport within the individual layers. These models are contrasted to the layered convection-dispersion model, which asumes continuous resident fluid concentration at the interface. Calculated concentrations are used to illustrate features of the different models, as well as to suggest experiments that might deduce the appropriate boundary condition to use at the interface between layers of different properties. The physical significance of various boundary condition assumptions is also discussed.     

Reproducing kernels, de Branges-Rovnyak spaces, and norms of weighted composition operators

We prove that the norm of a weighted composition operator on the Hardy space of the disk is controlled by the norm of the weight function in the de Branges-Rovnyak space associated to the symbol of the composition operator. As a corollary we obtain a new proof of the boundedness of composition operators on and recover the standard upper bound for the norm. Similar arguments apply to weighted Bergman spaces. We also show that the positivity of a generalized de Branges-Rovnyak kernel is sufficient for the boundedness of a given composition operator on the standard function spaces on the unit ball.

     

Operator-Valued Herglotz Kernels and Functions of Positive Real Part on the Ball

We describe several classes of holomorphic functions of positive real part on the unit ball; each is characterized by an operator-valued Herglotz formula. Motivated by results of J. E. McCarthy and M. Putinar, we define a family of weighted Cauchy–Fantappiè pairings on the ball and establish duality relations between certain pairs of classes, and in particular we identify the dual of the positive Schur class. We also establish the existence of self-dual classes with respect to this pairing, and identify some extreme points of the positive Schur class.     

Iron oxide superparamagnetic nanocarriers bearing amphiphilic N‐heterocyclic choline analogues as potential antimicrobial agents

Magnetic nanoparticles represent an advanced tool in biomedicine because they can be simultaneously functionalized and guided using a magnetic field. Iron oxide magnetic nanoparticles precoated with oleic acid and bearing novel antimicrobial N‐heterocyclic choline analogues, namely O‐, N‐ and O,N‐bis‐undecyl‐substituted N‐(2‐hydroxyethyl)‐1,2,3,4‐tetrahydroisoquinolinium derivatives, have been obtained as potential biomedical agents for drug delivery and antimicrobial therapy. Structural and size determinations for the novel synthesized magnetic nanosystems were carried out based upon magnetogranulometry, dynamic light‐scattering measurements and X‐ray diffraction analysis. The most expected iron oxide core diameter was 6.2–10.5 nm. The magnetization analyses showed that the particles are superparamagnetic at room temperature. Aqueous magnetic fluids of the synthesized nanoparticles were examined in vitro concerning Gram‐positive (Staphylococcus aureus MSCL 334, Bacillus cereus MSCL 330) and Gram‐negative (Escherichia coli MSCL 332, Pseudomonas aeruginosa MSCL 331, Proteus mirabilis MSCL 590) bacterial strains and fungi (Candida albicans MSCL 378, Aspergillus niger MSCL 324). It was found that the samples have magnetic properties and possess antimicrobial activity. The minimum inhibitory concentration against S. aureus for the most active magnetic fluid was determined as 16 µg ml^?1. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and reactivity of a putative biogenetic precursor to tricholomenyns B, C, D and E

A chemoenzymatic synthesis of the putative biogenetic precursor, 6, to the epoxy-quinol type natural products, tricholomenyns B, C, D and E (2-5, respectively), has been achieved. However, treatment of compound 6 under a variety of conditions failed to effect its conversion into any of the natural products 2-5. In contrast, the simple model system 22 reacts with acetic acid in the presence of stoichiometric quantities of Ti(OPr-i)₄ to give the diacetate 23.     

Derivatives of 1-H-2-benzazepin-1-one as unusual products of the Hantsch reaction

The use of opianic acid as the aldehyde component in the Hantsch reaction gives derivatives of 1-H-2-benzazepin-1-one instead of the expected 1,4-dihydropyridine derivatives. Latvian Institute of Organic Synthesis, LV-1006 Riga Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1408–1410, October, 1998.     

O-acylation of ketoximes of the furan and thiophene series in the liquid-solid body system under interphase catalysts conditions

The acrylation of 2-furanyl- and 2-thienylalkylketoximes by acyl chlorides in a two-phase catalytic system (solid K₂CO₃-C₆H₆-18-crown-6) at room temperature leads to a selective formation of the corresponding O-acetylketoximes in the form of a mixture of E- and Z-isomers.Latvian Institute of ORganic Synthesis, Riga, LV-1006. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 886–890, July, 1994. Original article submitted April 12, 1994.     

13C NMR spectra of 5-substituted 8-mercaptoquinolines

The increments of the substituents were determined from the ¹³C NMR spectra of 5-substituted quinolines. It is shown that the increments correlate with those in benzenes, as well as with the Swain-Lupton constants. The ¹³C chemical shifts of some 5-substituted 8-mercapto-, 8-(methylthio)-, and 8-hydroxyquinolines were investigated. Their values are in satisfactory agreement with the additive contribution. of the increments of the substituents. The deviations from additivity are associated with the steric hindrance to interaction of the substituents with the ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 932–936, July, 1981.