Exploring the Selective Demethylation of Aryl Methyl Ethers with a Pseudomonas Rieske Monooxygenase

Biocatalytic dealkylation of aryl methyl ethers is an attractive reaction for valorization of lignin components, as well as for deprotection of hydroxy functionalities in synthetic chemistry. We explored the demethylation of various aryl methyl ethers by using an oxidative demethylase from Pseudomonas sp. HR199. The Rieske monooxygenase VanA and its partner electron transfer protein VanB were recombinantly coexpressed in Escherichia coli and they constituted at least 25 % of the total protein content. Enzymatic transformations showed that VanB accepts NADH and NADPH as electron donors. The VanA–VanB system demethylates a number of aromatic substrates, the presence of a carboxylic acid moiety is essential, and the catalysis occurs selectively at the meta position to this carboxylic acid in the aromatic ring. The reaction is inhibited by the by-product formaldehyde. Therefore, we tested three different cascade/tandem reactions for cofactor regeneration and formaldehyde elimination; in particular, conversion was improved by addition of formaldehyde dehydrogenase and formate dehydrogenase. Finally, the biocatalyst was applied for the preparation of protocatechuic acid from vanillic acid, giving a 77 % yield of the desired product. The described reaction may find application in the conversion of lignin components into diverse hydroxyaromatic building blocks and generally offers potential for new, mild methods for efficient unmasking of phenols.     

High-Performance Membrane Chromatography of Small Molecules

High-performance membrane chromatography (HPMC) proved to be a very efficient method for fast protein separations. Recently, it was shown to be applicable also for the isocratic chromatography of plasmid DNA conformations. However, no study about the separation of small molecules has been performed until now. In this work, we investigated the possibility of gradient and isocratic HPMC of small molecules with Convective Interaction Media disks of different chemistries and tried to explain the mechanism that enables their separation. We demonstrated that it is possible to achieve efficient separations of oligonucleotides and peptides in the ion-exchange mode as well as the separation of small hydrophobic molecules in the reversed-phase mode. It was shown that similar peak resolution can be provided in both gradient and isocratic modes.     

An Algebra for Pomsets

We study languages for manipulatingpartially orderedstructures withduplicates(e.g., trees, lists). As a general framework, we consider thepomset(partially ordered multiset) data type. We introduce an algebra forpomsets, which generalizes traditional algebras for (nested) sets, bags, and lists. This paper is motivated by the study of the impact of different language primitives on the expressive power. We show that the use of partially ordered types increases the expressive power significantly. Surprisingly, it turns out that the algebra when restricted to both unordered (bags) and totally ordered (lists) intermediate types, yields the same expressive power as fixpoint logic with counting on relational databases. It therefore constitutes a rather robust class of relational queries. On the other hand, we obtain a characterization of PTIME queries on lists by considering only totally ordered types.     

Aesthetical criterion in art and science

Neural Computing and Applications - In the paper, the authors elaborate a recent research concerning the originality of artworks in terms of self-organization in the complex systems physics. It has...     

Target-based coherent beam combining of an optical phased array fed by a broadband laser source

The target-based phasing of an optical phased array (OPA) fed by a broadband master oscillator laser source is investigated. The specific scenario examined here considers an OPA phasing through atmospheric turbulence on a rough curved object. An analytical expression for the detected or received intensity is derived. Gleaned from this expression are the conditions under which target-based phasing is possible. A detailed OPA wave optics simulation is performed to validate the theoretical findings. Key aspects of the simulation set-up as well as the results are thoroughly discussed.     

Theoretical and Experimental Analysis of Moisture-Dependent Thermal Conductivity of Lightweight Ceramic Bricks

The moisture-dependent thermal conductivity of two types of lightweight ceramic brick body is analyzed using both theoretical and experimental approaches. The basic physical properties are determined at first. Then, an impulse method is applied for the thermal-conductivity measurement. Initially, the material samples are dried, after that, they are exposed to liquid water for specific time intervals, and finally the moisture content is allowed to homogenize within the whole volume. The thermal-conductivity measurement is performed for different moisture contents achieved in this way. In the theoretical part, the homogenization principles are used for the calculation of the moisture-dependent thermal conductivity, utilizing the distribution functions based on the pore-size distribution measurement. Finally, a comparison of the measured and calculated data is done, and the validity of the applied effective media treatment is assessed.     

Effect of reduction parameters on the particle size of tungsten monocarbide obtained from the blue tungsten oxide

Conclusions A study was made, using the methods of particle size analysis and metallographic examination, of the effects of temperature and bed thickness in the reduction of the blue tungsten oxide upon some properties of tungsten and tungsten monocarbide powders and sintered 6 wt.% Co hard alloys produced from the monocarbide powders. Quantitative results were obtained showing the relationship between these reduction parameters on the one hand and the particle size of the resultant powders and the physicomechanical properties of hard alloys on the other. It was established that the particle size grows with rise in reduction temperature and with increase in the thickness of the blue oxide bed.Translated from Poroshkovaya Metallurgiya, No. 11(143), pp. 102–107, November, 1974.     

Prenatal gunshot perforation of the colon

Digitoxin plasma levels were determined in the dog by radioimmunoassy after i.v. infusion of this cardenolide in toxic amounts (388 +/- 13 mug/kg). Plasma values found immediately after the administration of this dose were 588.5 +/- 91 ng/ml and attained very low levels (10 ng/ml) 96 h later. The dominant half-life of digitoxin in the dog was found to be 49.6 +/- 6.5 h, but this value was attained only in the final part of our study. The results found are compared with previous data and controversial aspects are discussed.