Kerogen as a geochemical marker of the thermal history of rocks

The study presents examples of the application of oxyreactive thermal analysis to the geological prospecting of bitumen deposits. Thermal analysis performed under properly chosen analytical conditions allows determination of characteristic features of organic matter and, at the same time, estimation of the thermal history of rocks. Thermal oxyreactivity curves document whether rocks were heated before or not. The results of the oxyreactive thermal analysis correlate well with the results of routine chemical analyses of organic matter (e.g. the composition of kerogen and bituminous fraction, Rock-Eval analysis and others). Our study clearly demonstrates that the composition of organic matter in facially, lithostratigraphically, and biogenetically identical rocks depends on their thermal history.     

Alkylation of the inverted porphyrin nickel(II) complex by dihalogenalkanes: formation of monomeric and dimeric derivatives

An efficient and simple method of modification of "inverted" porphyrin is provided by reactions of 5,10,15,20-tetraaryl-2-aza-21-carbaporphyrinatonickel(II) 2 with dihalogenalkanes under basic conditions. The substituents are bound to the internal carbon or external nitrogen of the inverted pyrrole depending on dihalogenalkane and basic catalyst. The monomeric 2- or 21-ethoxymethyl-substituted species are formed in the reaction of 2 with dihalomethanes and sodium ethoxide or ethanol in the presence of K(2)CO(3). A novel, dimeric 21,21'-ethylene-linked derivative 11 is obtained from 2 and ethylene bromide in dichloromethane in the presence of potassium carbonate end ethanol, while application of potassium tert-butoxide promotes formation of N-bromoethyl-substituted monomer 12. Reaction of 2 with propylene bromide in the presence of proton scavenger efficiently leads to the 21-allyl-substituted monomer 14 that is a product of the HBr elimination from a transient 21-bromopropyl-substituted species. The new compounds have been identified and characterized by means of mass spectrometry and optical and NMR spectroscopies. A single-crystal X-ray analysis performed for 12 allows discussion of structural parameters concerning the macrocycle and coordination core. Formation of deprotonated species [2](-), which is proposed as a key intermediate in the alkylation reaction, has been observed spectroscopically. Chirality of the N-substituted derivatives induced by protonation of the internal carbon is observed by NMR at low temperatures.     

The effect of solvent on the reactions of allyltin (IV) compounds with singlet oxygen, 4-phenyl-1,2,4-triazoline-3,5-dione and diethyl azodicarboxylate

The effect of the influence on the increase of polarity of the solvent on the selectivity and rate of metalloene reactions of different allyltin compounds with singlet oxygen, 4-phenyl-1,2,4-triazoline-3,5-dione (TD) and diethyl azodicarboxylate has been studied.     

Comparative Analysis of Acyclovir Esters Stability in Solutions: The Influence of the Substituent Structure,Kinetics, and Steric Effects

Reversed‐phase high‐performance liquid chromatography has been applied to the determination of acyclovir (ACV) esters such as acetate, isobutyrate, pivalate, ethoxycarbonate, and nicotinate. All analyses were carried out at laboratory temperature using a column LiChrospher RP‐18 (250 × 4 mm, 5 µm) and a proper mobile phase consisting of acetonitrile and phosphate buffer (pH 6 or 6.7) or acetonitrile and potassium dihydrogen phosphate, and acetic acid. The methods were validated by the determination of the following parameters: selectivity, precision, accuracy, and linearity. Kinetic studies on the hydrolysis were investigated in solutions at 310 K over the pH range 0.42–1.38. The pH‐profiles indicated specific acid‐catalyzed and spontaneous water‐catalyzed degradation. The stability of the studied ACV esters were determined not only by steric factors. In the case of ethoxycarbonyl ester of ACV, the hydrolysis was a two‐step reaction.     

Synthesis,characterisation, crystal structure and biological activity of metal(II) complexes with theophylline

Three metal complexes with empirical formulae [Mn(theop)₂(H₂O)₄] (1), [Co(theop)₂(H₂O)₄] (2), [Ni(theop)₂(H₂O)₄] (3), (where: theop?=?theophylline) were synthesized and characterized by elemental analysis, FTIR- spectroscopy and thermal decomposition techniques. Their crystal structures were determined by single crystal Xray diffraction analysis. Complexes are isomorphous and crystallise in the monocyclic space group P21/c. Their thermal behavior was studied by TGA methods under non-isothermal condition in air. Upon heating all compounds decompose progressively to metal oxides, which are the final products of pyrolysis. Furthermore, antimicrobial and antioxidant activity of the complexes was examined.     

Colloid‐Assisted Self‐Assembly of Robust,Three‐Dimensional Networks of Carbon Nanotubes over Large Areas

Natural materials, such as bone and spider silk, possess remarkable properties as a result of sophisticated nanoscale structuring. They have inspired the design of synthetic materials whose structure at the nanoscale is carefully engineered or where nanoparticles, such as rods or wires, are self‐assembled. Although much work has been done in recent years to create ordered structures using diblock copolymers and template‐assisted assembly, no reports describe highly ordered, three‐dimensional nanotube arrays within a polymeric material. There are only reports of two‐dimensional network structures and structures on micrometer‐size scales. Here, we describe an approach that uses plasticized colloidal particles as a template for the self‐assembly of carbon nanotubes (CNTs) into ordered, three‐dimensional networks. The nanocomposites can be strained by over 200% and still retain high conductivity when relaxed. The method is potentially general and so may find applications in areas such as sensing, photonics, and functional composites.

     

The automorphism group of a split metacyclic 2-group and some groups of crossed homomorphisms

In this paper we find the structure for the automorphism group of a split metacyclic 2-group G. It can be seen as a continuation of the paper (Curran in Arch. Math. 89 (2007), 10–23) and it makes it complete. We propose a different approach to the problem than in the paper (Curran in Arch. Math. 89 (2007), 10–23). Our intention is to show that apart from some cases of 2-groups AutG has a structure similar to that of a direct product of two groups with no common direct factor [which was considered in Bidwell, Curran, and McCaughan (Arch. Math. 86 (2006), 481–489)].      

Strong solutions to stochastic Volterra equations

In this paper stochastic Volterra equations admitting exponentially bounded resolvents are studied. After obtaining convergence of resolvents, some properties for stochastic convolutions are studied. Our main results provide sufficient conditions for strong solutions to stochastic Volterra equations.