Modeling Alcohol Dehydrogenase Catalysis in Deep Eutectic Solvent/Water Mixtures

The use of oxidoreductases (EC1) in non-conventional reaction media has been increasingly explored. In particular, deep eutectic solvents (DESs) have emerged as a novel class of solvents. Herein, an in-depth study of bioreduction with an alcohol dehydrogenase (ADH) in the DES glyceline is presented. The activity and stability of ADH in mixtures of glyceline/water with varying water contents were measured. Furthermore, the thermodynamic water activity and viscosity of mixtures of glyceline/water have been determined. For a better understanding of the observations, molecular dynamics simulations were performed to quantify the molecular flexibility, hydration layer, and intraprotein hydrogen bonds of ADH. The behavior of the enzyme in DESs follows the classic dependence of water activity (a_W) in non-conventional media. At low a_W values (<0.2), ADH does not show any activity; at higher a_W values, the activity was still lower than that in pure water due to the high viscosities of the DES. These findings could be further explained by increased enzyme flexibility with increasing water content.     

Current Trends in Pretreatment and Fractionation of Lignocellulose as Reflected in Industrial Patent Activities

The pretreatment process to disintegrate lignocellulose and to fractionate its three main components hemicellulose, cellulose, and lignin, is a crucial step to enable sustainable and economic value chains based on biomass feedstock. This review provides an overview of the recent patenting activities on pretreatment. Most of these activities focus on optimization of different known processes to improve economics, such as increased catalyst efficiency, effluents recirculation, or lignin valorization. However, also a number of patents and demonstration activities based on emerging concepts for pretreatments are observed.     

Dual,Site‐Specific Modification of Antibodies by Using Solid‐Phase Immobilized Microbial Transglutaminase

Microbial transglutaminase (MTG) was stably solid‐phase immobilized on glass microbeads by using a second‐generation dendronized polymer. Immobilized MTG enabled the efficient generation of site‐specifically conjugated proteins, including antibody fragments, as well as whole antibodies through distinct glutamines and, unprecedentedly, also through lysines with various bifunctional substrates with defined stoichiometries. With this method, we generated dual, site‐specifically modified antibodies comprising a fluorescent probe and a metal chelator for radiolabeling—a strategy anticipated to design antibodies for imaging and simultaneous therapy. Furthermore, we provide evidence that immobilized MTG features higher siteselectivity than soluble MTG.     

Dissolution,Transport and Reaction at a DICY/DGEBA Interface

The curing of an epoxy consisting of the solid hardener dicyandiamide (DICY) and the resin diglycidyl ether of bisphenol A (DGEBA) is studied in a system consisting of a tablet of DICY embedded in liquid DGEBA. Dissolution of DICY within the liquid DGEBA in combination with the transport of dissolved DICY from the tablet border into DGEBA and the chemical reaction of both reactants is studied by scanning Brillouin microscopy and infrared spectroscopy. Scanning Brillouin microscopy demonstrates the spatial and temporal evolution of the static and dynamic hypersonic properties in the course of curing in the vicinity of the DICY tablet. Infrared spectroscopy performed on epoxy pieces extracted from the final sample at different distances from the tablet surface give information about the spatial evolution of the curing process. The results achieved by both techniques are finally combined to yield a better understanding of the curing of DICY-based epoxies, which transform upon curing from strongly heterogeneous systems towards increasingly homogeneous systems.     

Increase in energy and land use by a bio-based chemical industry

About 80% of the chemical products are still based on crude oil. Bio-based materials will increasingly gain importance. As the fraction of oxygen is normally higher in biomass than in crude oil as well as in the derived conventional products, this implies a need to develop new synthesis pathways. Depending on the types of new synthesis pathways, the effects of a complete raw-material change on land and exergy use differ. Here, different synthesis pathways starting from glucose and plant oil to different kinds of end products are evaluated utilizing material and exergy balances. These evaluations are carried out under today's and future conditions and constraints, like yield, demand of organic chemicals and world population. The analysis in this paper shows that the land and energy use can be significantly reduced, if the products are adapted to the chemical structure of their bio-based feedstock.     

Formation Mechanism of Alkyl Nitrites,Valuable Intermediates in C1-Upgrading Chemistry and Oxidation Processes

In this contribution we use computational tools to investigate the reaction of alcohol substrates with reactive nitrogen oxide species such as N₂O₃ and N₂O₄, leading to the formation of alkyl nitrites. These nitrites are interesting intermediates which can be processed to various valuable chemicals such as ketones/aldehydes and dimethyl oxalate while regenerating NO _x . As such, NO _x is used as an oxidation mediator, converting alcohol substrates to more reactive nitrites which can be selectively converted to more desired compounds, closing a catalytic cycle in NO _x species.     

Metamer density estimated color correction

Color correction is the transformation of response values of scanners or digital cameras into a device- independent color space. In general, the transformation is not unique due to different acquisition and viewing illuminants and non-satisfaction of the Luther–Ives condition by a majority of devices. In this paper we propose a method that approximates the optimal color correction in the sense of a minimal mean error. The method is based on a representative set of reflectance spectra that is used to calculate a special basic collection of device metameric blacks and an appropriate fundamental metamer for each sensor response. Combining the fundamental metamer and the basic collection results in a set of reflectances that follows the density distribution of metameric reflectances if calculated by Bayesian inference. Transforming only positive and bounded spectra of the set into an observer’s perceptually uniform color space results in a point cloud that follows the density distribution of device metamers within the metamer mismatch space of acqcuisition system and human observer. The mean value of this set is selected for color correction, since this is the point with a minimal mean color distance to all other points in the cloud. We present the results of various simulation experiments considering different acquisition and viewing illuminants, sensor types, noise levels, and existing methods for comparison.     

A Rank Encoder: Adaptive Analog to Digital Conversion Exploiting Time Domain Spike Signal Processing

An electronic circuit is presented that encodes an array of analog input signals into a digital number. The digital output is a rank order code that reflects the relative strength of the inputs, but is independent of the absolute input intensities. In that sense, the circuit performs an adaptive analog to digital conversion, adapting to the average intensity of the inputs (i.e. effectively normalizing) and adapting the quantization levels to the spread of the inputs. Thus, it can convey essential information with a minimal amount of output bits over a huge range of input signals.As a first processing step the analog inputs are projected into the time domain, i.e. into voltage spikes. The latency of those spikes encodes the strength of the input. This conversion enables the circuit to conduct further analog processing steps by asynchronous logic.