Temperature dependence of the configurational free energy of a branched polymer

We consider a lattice model of branched polymers in dilute solution in which the polymer is modelled as an animal, weakly embeddable in the (simple cubic) lattice. In order to model the effect on the thermodynamic properties of changing the temperature or the quality of the solvent, we include an energy associated with the number of nearneighbour contacts between pairs of vertices of the animals. We show that the configurational free energy of the animal is a continuous function of the temperature and derive rigorous upper and lower bounds on the temperature dependence of the free energy. Finally, we comment on similarities between these results and corresponding ones for a model in which the energy is associated with the cyclomatic index of the animal.     

Methyltriazolocoumarins: New furocoumarin isosters as potential photochemotherapeutic agents

A number of new methyltriazolocoumarins with a linear psoralen-like structure or an angular angelicin-like structure were synthetized. The syntheses were performed starting from the appropriate methylated 7-aminocoumarins which were nitrated, reduced and successively diazotized with concomitant cyclization to form the condensed triazolo ring. The new methyltriazolocoumarins show promising spectroscopic properties which are potentially predictive of their photochemical and photobiological behaviour.     

Synthesis of 4-allyl-4-arylaminopiperidines and their transformations to spiro[tetrahydroquinoline-2,4′-piperidines]

It was established that the yields of a 4-allyl-4-aryl-aminopiperidines in the reaction of 4-aryliminopiperidines with allylmagnesium bromide increase significantly if the reaction is carried out in the presence of a crown ether. A number of previously unknown spiro[tetrahydroquinoline-2,4-piperidines] were obtained in the cyclization of 4-allyl-4-arylaminopiperidines in the presence of sulfuric acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1514–1519, November, 1989.     

A sum rule approach to collective spin modes in paramagnetic clusters,cavities and shells

We study spin collective modes in paramagnetic systems using a sum rule approach. We give a simple and analytical expression for the static magnetic polarizability of finite size systems in terms of their radii and of the magnetic susceptibility of a uniform system. A systematics for the mean excitation energy of spin modes in clusters and shells is given. In metal spheres, the hydrodynamical model is solved and compared with the sum rule approach. An estimate for the mean excitation energy of the spin dipole collective state in fullerene is given.     

Extractive substances formed from buckwheat grain production waste

Properties of liquid and dry extracts produced in treatment of buckwheat fruit shells (husk) and straw with water or an acid solution were studied. The conditions of pigment concentration from aqueous extracts by ultrafiltration were determined.     

Photosensitivity of holographic recording media based on films of polymer compositions with cadmium sulfide nanoparticles

The effect of doping with CdS nanoparticles of recording medium films for the thermoplastic holographic recording process, which are based on photosemiconductors (oligomers and cooligomers of glycidylcarbazole) and a dielectric (a styrene copolymer with octyl methacrylate) containing a photoconductivity sensitizer, on their photosensitivity was studied. The enhancement of photosensitivity of films by doping with nanoparticles is associated with the appearance of an additional channel for transport of electrons generated from sensitizer molecules. A difference in informational properties between the oligomer and the polymer films was revealed.     

Quick Determination of the Total Content of Aromatic Hydrocarbons in Reformer Naphthas by <Superscript>1</Superscript>H NMR Spectroscopy

A procedure for fast determination of the total content of arenes in reformer naphthas by ¹H NMR spectroscopy was developed and tested. Their content is determined from the ratio of the integral intensities of the signals of aromatic protons and alkane methyl protons, using a calibration plot constructed on the basis of GLC data.