Diastereoselective synthesis of optically active (2R,5R)-hexanediol

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)Diastereoselective reduction of diketones with Lactobacillus kefir DSM 20587 was examined. The reduction of both oxo-functions proceeded highly diastereoselectively. (2R,5R)-Hexanediol 3 was produced starting from (2,5)-hexanedione 1 in quantitative yields with enantiomeric excess >99% and diastereomeric excess >99%. The reaction conditions were optimized: maximum yield of (2R,5R)-hexanediol was reached at pH 6, 30°C and with equal amounts of substrate and cosubstrate. The applicability of the system in fed-batch experiments was demonstrated. The feed specific biomass concentration required to reach maximal yield and selectivity in fed-batch mode was determined

Hydration effects turn a highly stretched polymer from an entropic into an energetic spring

Polyethylene glycol (PEG) is a structurally simple and nontoxic water-soluble polymer that is widely used in medical and pharmaceutical applications as molecular linker and spacer. In such applications, PEG’s elastic response against conformational deformations is key to its function. According to text-book knowledge, a polymer reacts to the stretching of its end-to-end separation by a decrease in entropy that is due to the reduction of available conformations, which is why polymers are commonly called entropic springs. By a combination of single-molecule force spectroscopy experiments with molecular dynamics simulations in explicit water, we show that entropic hydration effects almost exactly compensate the chain conformational entropy loss at high stretching. Our simulations reveal that this entropic compensation is due to the stretching-induced release of water molecules that in the relaxed state form double hydrogen bonds with PEG. As a consequence, the stretching response of PEG is predominantly of energetic, not of entropic, origin at high forces and caused by hydration effects, while PEG backbone deformations only play a minor role. These findings demonstrate the importance of hydration for the mechanics of macromolecules and constitute a case example that sheds light on the antagonistic interplay of conformational and hydration degrees of freedom

Электрохимические свойства наночастиц серебра на графитовом электроде

В настоящей работе было показано, что наночастицы серебра, полученные при молярном соотношении реагентов [AgNO3]: [Na3C6H5O7] = 1:1 в условии отсутствии стабилизатора с высоким молекулярным весом, обладают максимальной электрохимической активностью, что связано с неполным восстановлением ионов серебра. Этот факт соотносится с данными УФ-спектроскопии. Наночастицы серебра, полученные в избытке восстановителя при молярном соотношении реагентов [AgNO3]: [Na3C6H5O7] = 1:5 электрохимически неактивны, что также соответствует данным УФ- спектроскопии. Увеличение активности наночастиц серебра происходит в условии увеличения диапазона изменения потенциала, что может быть вызвано образованием перекиси водорода, обладающей активационной способностью. В данной работе установлены оптимальные условия, в которых наночастицы серебра являются наиболее электрохимически активны

Quantitative and Non‐Quantitative Assessments of Enzymatic Electrosynthesis: A Case Study of Parameter Requirements

The integration of enzymatic and electrochemical reactions offers a unique opportunity to optimize production processes. Recently, an increasing number of laboratory-scale enzymatic electrosyntheses have shown impressive performance indicators, leading to scientific interest in technical implementation. However, important process parameters are missing in most of the relevant literature. On one hand, this is due to the large variety of relevant performance indicators. On the other hand, enzyme technologists and electrochemists use different parameters to describe a process. In this article, we review the most important performance indicators in electroenzymatic processes and suggest that in order to allow quantitative comparison, these indicators should be reported in all respective publications. In addition to quantitative parameters, non-quantitative assessments often need to be included in a final evaluation. Examples of such parameters are sustainability, contribution to the UN Sustainable Development Goals or interactions with the overall process. We demonstrate the evaluation of processes using hydrogen peroxide-dependent peroxygenases. The strength of the proposed evaluation system lies in its ability to identify weaknesses in a process at an early stage of development. Finally, it can be concluded that all evaluated enzymatic electrosynthesis do not yet meet typical industrial requirements for an enzyme-based process

Fermentative oxidation of butane in bubble column reactors

To date the use of alkanes as starting materials for selective activation in chemical industry is very challenging. For this task the biocatalytic selective activation offers a number of advantages. The activation starts with C-H functionalization by a sequence of oxidation steps via alcohols, aldehydes/ ketones and carboxylic acids. All these derivatives are bulk-scale products, which are produced with standard chemical methods using high pressures and temperatures. In contrast, microorganisms are able to convert alkanes to various organic compounds at ambient pressure and temperature.[1] For the selective and efficient functionalization of alkanes appropriate fermentation of cells is required. Process engineering is required for a high yielding butane oxidation as well as reactor design. In this context it is essential to investigate the parameters of cell growth and to establish control of the fermentation conditions for production of the hydroxylated target compounds. At first a suitable reactor set up in accordance to the safety regulations required for handling a flammable gas like butane had to be installed to enable reaction engineering studies of the cell and reactor system. Specialized bubble column reactors are developed on lab scale and characterized in view of the implementation at industrial scale.[2] Additionally, a suitable control system was designed to monitor as well as control standard parameters and to simplify the implementation of further equipment. The mass transfer of the gaseous starting materials into the fermentation media is the key limiting factor for reaching sufficient productivities. The process window is mainly restricted by the requirements of the microorganisms and the flammability region of the substrates. Please click Additional Files below to see the full abstract

Design and functional analysis of heterobifunctional multivalent phage capsid inhibitors blocking the entry of influenza virus

Multiple conjugation of virus-binding ligands to multivalent carriers is a prominent strategy to construct highly affine virus binders for the inhibition of viral entry into host cells. In a previous study, we introduced rationally designed sialic acid conjugates of bacteriophages (Q beta) that match the triangular binding site geometry on hemagglutinin spike proteins of influenza A virions, resulting in effective infection inhibition in vitro and in vivo. In this work, we demonstrate that even partially sialylated Q beta conjugates retain the inhibitory effect despite reduced activity. These observations not only support the importance of trivalent binding events in preserving high affinity, as supported by computational modeling, but also allow us to construct heterobifunctional modalities. Capsids carrying two different sialic acid ligand-linker structures showed higher viral inhibition than their monofunctional counterparts. Furthermore, capsids carrying a fluorescent dye in addition to sialic acid ligands were used to track their interaction with cells. These findings support exploring broader applications as multivalent inhibitors in the future

La organización de la información, los lenguajes documentales y la normalización

La calidad de la información que se maneja actualmente ha aumentado debido a las nuevas tecnologías. Esta comunicación se plantea la calidad de la información que los bibliotecarios ofrecen a sus usuarios a través de diversas herramientas : control de autoridades, normalización, normas bibliográficas, lenguajes documentales y encabezamientos de materia

Public health impact and cost-effectiveness of intranasal live attenuated influenza vaccination of children in Germany

Damm O, Eichner M, Rose MA, et al. Public health impact and cost-effectiveness of intranasal live attenuated influenza vaccination of children in Germany. The European Journal of Health Economics. 2015;16(5):471-488.In 2011, intranasally administered live attenuated influenza vaccine (LAIV) was approved in the EU for prophylaxis of seasonal influenza in 2-17-year-old children. Our objective was to estimate the potential epidemiological impact and cost-effectiveness of an LAIV-based extension of the influenza vaccination programme to healthy children in Germany. An age-structured dynamic model of influenza transmission was developed and combined with a decision-tree to evaluate different vaccination strategies in the German health care system. Model inputs were based on published literature or were derived by expert consulting using the Delphi technique. Unit costs were drawn from German sources. Under base-case assumptions, annual routine vaccination of children aged 2-17 years with LAIV assuming an uptake of 50 % would prevent, across all ages, 16 million cases of symptomatic influenza, over 600,000 cases of acute otitis media, nearly 130,000 cases of community-acquired pneumonia, nearly 1.7 million prescriptions of antibiotics and over 165,000 hospitalisations over 10 years. The discounted incremental cost-effectiveness ratio was a,not sign1,228 per quality-adjusted life year gained from a broad third-party payer perspective (including reimbursed direct costs and specific transfer payments), when compared with the current strategy of vaccinating primarily risk groups with the conventional trivalent inactivated vaccine. Inclusion of patient co-payments and indirect costs in terms of productivity losses resulted in discounted 10-year cost savings of a,not sign3.4 billion. In conclusion, adopting universal influenza immunisation of healthy children and adolescents would lead to a substantial reduction in influenza-associated disease at a reasonable cost to the German statutory health insurance system. On the basis of the epidemiological and health economic simulation results, a recommendation of introducing annual routine influenza vaccination of children 2-17 years of age might be taken into consideration

Design and Functional Analysis of Heterobifunctional Multivalent Phage Capsid Inhibitors Blocking the Entry of Influenza Virus

Multiple conjugation of virus-binding ligands to multivalent carriers is a prominent strategy to construct highly affine virus binders for the inhibition of viral entry into host cells. In a previous study, we introduced rationally designed sialic acid conjugates of bacteriophages (Qβ) that match the triangular binding site geometry on hemagglutinin spike proteins of influenza A virions, resulting in effective infection inhibition in vitro and in vivo. In this work, we demonstrate that even partially sialylated Qβ conjugates retain the inhibitory effect despite reduced activity. These observations not only support the importance of trivalent binding events in preserving high affinity, as supported by computational modeling, but also allow us to construct heterobifunctional modalities. Capsids carrying two different sialic acid ligand–linker structures showed higher viral inhibition than their monofunctional counterparts. Furthermore, capsids carrying a fluorescent dye in addition to sialic acid ligands were used to track their interaction with cells. These findings support exploring broader applications as multivalent inhibitors in the future