Search

Abstract Coalification temperatures are often considered to be approximately 100–170 °C for bituminous coal and 170–275 °C for anthracite. However, our micropetrographic observations, solid state 27Al magic-angle spinning nuclear magnetic resonance measurements, interpretation of δ 13C values for whewellite in pelosiderite concretions from Carboniferous sediments, and assessment of whewellite thermal stability show that coalification temperatures can be significantly lower. Also the temperatures of coal alteration may be substantially lower than is stated. Ordinarily, high-temperature alteration is reported, but microthermometric measurements of fluids temperatures and micropetrographic observations show that the coal alteration can take place at low temperatures. For this reason, coals from the Kladno–Rakovník Basin, part of Late Paleozoic continental basins of the Czech Republic, were analyzed. Regarding coalification, micropetrographic characterizations of unaltered coals, the presence of thermally unstable Al complexes in the coal organic mass documented using 27Al MAS NMR method, and proven occurrence of whewellite in pelosiderite concretions suggest a lower coalification temperature, max. ~ 70 °C. Regarding coal alteration, micropetrographic observations revealed (a) the weaker intensity of fluorescence of liptinite, (b) mylonitic structures and microbreccia with carbonate fluid penetration, and (c) high oxygen content in coals (37–38 wt.%). These phenomena are typical for thermal and oxidative alteration of coal. As the temperature of carbonate fluids inferred from fluid inclusion analysis was evaluated as ~ 100–113 °C, the temperature of coal alteration was suggested as ~ 113 °C; the alteration was caused by hot hydrothermal fluids.

Coalification temperatures are often considered to be approximately 100-170 °C for bituminous coal and 170-275 °C for anthracite. However, our micropetrographic observations, solid state 27Al magic-angle spinning nuclear magnetic resonance measurements, interpretation of δ13C values for whewellite in pelosiderite concretions from Carboniferous sediments, and assessment of whewellite thermal stability show that coalification temperatures can be significantly lower. Also the temperatures of coal alteration may be substantially lower than is stated. Ordinarily, high-temperature alteration is reported, but microthermometric measurements of fluids temperatures and micropetrographic observations show that the coal alteration can take place at low temperatures. For this reason, coals from the Kladno-Rakovník Basin, part of Late Paleozoic continental basins of the Czech Republic, were analyzed. Regarding coalification, micropetrographic characterizations of unaltered coals, the presence of thermally unstable Al complexes in the coal organic mass documented using 27Al MAS NMR method, and proven occurrence of whewellite in pelosiderite concretions suggest a lower coalification temperature, max. ~ 70 °C. Regarding coal alteration, micropetrographic observations revealed (a) the weaker intensity of fluorescence of liptinite, (b) mylonitic structures and microbreccia with carbonate fluid penetration, and (c) high oxygen content in coals (37-38 wt.%). These phenomena are typical for thermal and oxidative alteration of coal. As the temperature of carbonate fluids inferred from fluid inclusion analysis was evaluated as ~ 100-113 °C, the temperature of coal alteration was suggested as ~ 113 °C; the alteration was caused by hot hydrothermal fluids. [ABSTRACT FROM AUTHOR]

The article presents results of a density functional theoretical study on the on the C-F and C-O oxidative addition reaction to the Al complex NacNacAl. Topics discussed include the Gibbs energies of activation for the oxidative addition reactions that were evaluated through density functional theoretical (DFT); and computational results showing that the DFT calculations could provide qualitative insight into the reactivity and thermodynamics of the oxidative addition reactions of C-F bonds.

Abstract: The paper gives a review on the importance of distribution of Al in biological fluids, primarily in the lights of the works of the author in Al chemistry. It starts with studies of interactions of Al(III) with small biomolecules, such as aliphatic and aromatic hydroxycarboxylic acids, and inorganic and organic phosphates. A significant part of this review deals with the problems of description of the biospeciation of Al(III) in serum, where besides the thermodynamic conditions the role of time is also considered in the case of this sluggish metal ion. The Al(III) complexes of the other large group of biomolecules, proteins and their building blocks (oligo)peptides and amino acids are also discussed, where the role of the type of the side chain donors and the extent of preorganisation are considered in the efficiency of metal ion binding. The application of low molecular mass chelator molecules in restoring the dysfunctioning metal ion (including Al(III)) homeostasis in the treatment of Alzheimer's disease is also discussed in the paper. [Copyright &y& Elsevier]

Abstract: We aimed to increase the efficiency of adenoviral vectors by limiting adenoviral spread from the target site and reducing unwanted host immune responses to the vector. We complexed adenoviral vectors with DDAB–DOPE liposomes to form adenovirus–liposomal (AL) complexes. AL complexes were delivered by intratumoral injection in an immunocompetent subcutaneous rat tumor model and the immunogenicity of the AL complexes and the expression efficiency in the tumor and other organs was examined. Animals treated with the AL complexes had significantly lower levels of β-galactosidase expression in systemic tissues compared to animals treated with the naked adenovirus (NA) (P <0.05). The tumor to non-tumor ratio of β-galactosidase marker expression was significantly higher for the AL complex treated animals. NA induced significantly higher titers of adenoviral-specific antibodies compared to the AL complexes (P <0.05). The AL complexes provided protection (immunoshielding) to the adenovirus from neutralizing antibody. Forty-seven percent more β-galactosidase expression was detected following intratumoral injection with AL complexes compared to the NA in animals pre-immunized with adenovirus. Conclusions: Complexing of adenovirus with liposomes provides a simple method to enhance tumor localization of the vector, decrease the immunogenicity of adenovirus, and provide protection of the virus from pre-existing neutralizing antibodies. [Copyright &y& Elsevier]

Abstract: Adenoviral vectors have been commonly used in gene therapy protocols, however the success of their use is often limited by the induction of host immunity to the vector. Following exposure to the adenoviral vector, adenoviral-specific neutralising antibodies are produced which limits further administration. This study examines the efficacy of complexing liposomes to adenovirus for the protection of the adenovirus from neutralising antibodies in an in vitro setting. Dimethyldioctadecylammonium bromide (DDAB)–dioleoyl-l-phosphatidylethanolamine (DOPE) liposomes were bound at varying concentrations to adenovirus to form AL complexes and tested these complexes’ ability to prevent adenoviral neutralisation. It is shown that by increasing the concentration of liposomes in the adenoviral–liposome (AL) complexes we can increase the level of immuno-shielding afforded the adenovirus. It is also shown that the increase in liposomal concentration may lead to drawbacks such as increased cytotoxicity and reductions in expression levels. [Copyright &y& Elsevier]