The unified theory of Davydov's and Fröhlich's models

Starting from the experimental facts and from quite general theoretical assumptions a theoretical model was formulated and the Hamiltonian derived which describes the possible excitations in a biological system. Davydov's and Fröhlich's models are also devoted to the same problem, although it seems that these models are not connected. Our results show that the Hamiltonians of Davydov's and Fröhlich's models can be easily obtained from the Hamiltonian of our model. More precisely, our theory could be considered as the microscopic theory of Fröhlich's model, from which Davydov's theoretical model follows as a particular case.     

DSC investigation of isothermal bulk copolymerization of alkylaryl methacrylates

The free radical copolymerization of phenyl methacrylate (PhMA) witho-methylphenyl-methacrylate(o-MPhMA) ando-ethylphenyl methacrylate (o-EPhMA) was carried out and the enthalpies of copolymerization, overall rate constants and copolymerization parameters were determined for different molar ratios of comonomers in the temperature range 353–373 K.     

Positional and conformational dependence of long-range interactions in 3,16- and 3,17-androstanediones

The 5- and 5-conformations of androstane, androstan-3-one, androstan-16-one, androstan-17-one, androstane-3,16-dione and androstane-3,17-dione have been calculated by the SCF MNDO method, using full geometry optimization, in order to assess the dependence of long-range electronic interactions of the carbonyl groups on their location and on the conformation of the steroid ring system.     

Multielement Analysis of South Serbian Strawberry Cultivars by Inductively Coupled Plasma—Optical Emission Spectrometry

The contents of 17 elements in thirteen strawberry cultivars grown in the five districts of Southern Serbia were determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The most abundant elements are K (875–1148 mg?·?kg^?1 fresh weight), P (307–664 mg?·?kg^?1 fresh weight), Ca (192–256 mg?·?kg^?1 fresh weight), and Mg (111–189 mg?·?kg^?1 fresh weight) in all samples. Strawberries were also found to be a good source of Sr (8.05–18.6 mg?·?kg^?1 fresh weight) and Fe (3.09–10.4 mg?·?kg^?1 fresh weight). The contents of As and Cd were below the detection limit (0.0828 mg?·?kg^?1 and 0.0205 mg?·?kg^?1, respectively) in all strawberry samples, while the contents of Ni, Cr, and Cu were below the recommended tolerable levels proposed by Joint Food and Agriculture Organization of the United Nations and World Health Organization Expert Committee on Food Additives, and did not a pose a health risk for the consumer. The application of Duncan’s test showed significant differences between contents of analyzed elements in all strawberry cultivars. The highest mean levels of analyzed elements were detected in strawberries grown in the Topli?ki, Jablani?ki, and P?injski districts. The spike recovery test was used to verify the accuracy of the method, and the spike recovery was in the range 93.8–107.8%. The contents of the metals in strawberry samples were also comparable with values previously reported in the literature.     

Kinetic model for the Bray-Liebhafsky process without the reaction IO3?+I?+2H+?HIO+HIO2

Oscillations in the concentration of intermediates were obtained when a model without reaction IO ₃ ^– +I^–+2H⁺HIO+HIO₂ was used for the simulation of the Bray-Liebhafsky process.     

Transition-metal complexes with hydrazides and hydrazones

Several new complexes of dioxomolybdenum(VI) of the general formula [MoO₂(L)S], whereL is the dianion of salicylaldehydep-hydroxybenzoylhydrazone andS denotes H₂O, MeOH, py, PPh₃, DMSO or DMF, were synthesized and characterized by elemental analysis, electronic UV-VIS and IR spectra, thermal analysis, molar conductivity and magnetic susceptibility measurements. Salicylaldehydep-hydroxybenzoylhydrazone participates in the coordination as a tridentate ligand with the ONO set of donor atoms. The complexes contain acis-MoO₂ group and are of octahedral geometry. Complexes of the MoO₂L type were also prepared by synthesis in CHCl₃ solution and by isothermal heating of [MoO₂(L)S] complexes. The MoO₂L complex synthesized in CHCl₃ solution has most probably a pentacoordinated structure while the complex obtained by isothermal heating of [MoO₂(L)S] has a polymeric hexacoordinated structure.The authors are grateful to the Serbian Republic Research Fund for financial support and to academician Prof. M. ui for his interest in this work.     

METABOLISM OF NUCLEIC ACIDS IN U.V. IRRADIATED L-STRAIN CELLS TREATED WITH NATIVE DEOXYRIBONUCLEIC ACID

Abstract— In our earlier papers we described the recovery of U.V. irradiated L-strain cells by means of nucleic acids. In an attempt to get better insight in the mechanism(s) leading to this recovery we studied the effect of native DNA on the metabolism of nucleic acids of recipient cells. In these experiments we have found that the label isologous DNA-C¹⁴ is incorporated in DNA of normal and irradiated recipient cells. The rate of DNA-C¹⁴ label incorporation in the DNA of irradiated recipient cells is slower than in the unirradiated controls. The presence of thymidine in the incubation media reduces the incorporation rate of DNA-C¹⁴. When the irradiated cells have been growing in a medium containing isologous DNA in presence of thymidine or heterologous DNA the recovery effect was not observed.     

Deuterium-induced 13C NMR isotope shifts for signal assignments and determination of deuteriation site in cyclododecanone

Deuterium-induced ¹³C isotope shifts were measured in the ¹³C {¹H} NMR spectra of monodeuteriated cyclododecanones formed upon oxidation of [1-²H₁] cyclododecanol with lead tetraacetate. These shifts, when used in conjunction with ¹³C NMR data of specifically labelled analogues, [2, 2, 12, 12-²H₄]- and [2-²H₁] cyclododecanone, enabled the ketone formed with lead tetraacetate to be identified as a mixture of [5-²H₁]- and [6-²H₁] isotopomers.     

Coulometric generation of H+ ions by oxidation of thiols at a platinum anode and by oxidation of mercury in acetic acid—acetic anhydride

The coulometric generation of hydrogen ions by anodic oxidation of propane-1-thiol, butane-1-thiol, 2-mercaptopropionic acid, heptane-1-thiol, 2-mercaptoethanol, methyl and ethyl thioglycollate and p-thiocresol in acetic acid—acetic anhydride (1 + 6 v/v) is described, together with the possibility of coulometric generation of protons by mercury oxidation in the presence of p-thiocresol in the same solvent system.Current-potential curves for the solvent, indicator, titrated bases, mercury and the investigated thiols showed that in acetic acid—acetic anhydride (5 + 95, v/v), mercury and the investigated thiols are oxidized at potentials which are much more negative than those of the titrated bases and other components present in the solution.Titration of potassium hydrogenphthalate and sodium acetate with protons generated by the oxidation of thiols, and of sodium acetate, lithium acetate and pyridine with protons generated by the oxidation of mercury, demonstrated that the oxidation of both thiols and mercury proceeds quantitatively with 100% current efficiency.     

Retention behaviour and molecular structure of the solute in thin-layer chromatography

Summary Dual retention behaviour on cellulose, silica and alumina in thin-layer chromatography, that is, the separation of solutes either in normal phase or in reversed phase mode is discussed as a function of the mobile phase polarity utilizing the solubility parameter theory and then correlated with the molecular structure of the solute.