Ressourcenschonung und Kreislaufführung in der Prozessindustrie

Efficient use of material and energy flows increases the competitiveness of manufacturing companies and saves the environment at the same time. In order to significantly reduce the use of non-renewable materials and energy, a change from a linear to a closed-loop production process is necessary. In recent years, various closed-loop strategies have been developed, implemented or are in the process of being implemented. In this paper, a brief overview of approaches for a circular economy in the process industry is given.     

Multienzymatic immobilization of laccases on polymeric microspheres: A strategy to expand the maximum catalytic efficiency

Laccase enzymes of were covalently coimmobilized on poly(glycidyl methacrylate) microspheres. The objective of this work was to create a biocatalyst that works efficiently in a wide range of pH. The coimmobilization was performed using two different strategies to compare the most efficient. The results showed that by correctly selecting the enzymes and concentrations involved in the commobilization, it is possible to obtain a biocatalyst that works efficiently at a wide pH range (2.0–7.0). The maximum activity values reached per gram of support for the obtained biocatalyst were 41.90 U (pH 3.0), 40.89 U (pH 4.0), and 39.54 U (pH 6.0). Moreover, the thermal, storage, and mechanical stabilities were improved compared to the free and single-immobilized laccases. It was concluded that enzymatic coimmobilization is an excellent alternative to obtain a robust biocatalyst that works in a wide pH range, with potential environmental and industrial applications.     

A Concept for an Integrated Process Scheme for By-Products from Rice and Sugarcane Processing

The material use of agricultural by-products helps to not only reduce severe environmental problems, but also permits the production of value-added products at the same time. Extensive experiments produced and tested different erosion control blankets, adsorbents, and soil improvers from rice straw, rice husks, and bagasse. This led to the creation of an integrated process scheme, which permits side streams from one branch to be reused in other process branches. This integrated process scheme is presented that is demonstrated and supported by the material balance numbers based on the test results.     

Flow Fields in Stirred Vessels Depending on Different Internal Heat Exchangers and Vessel Bottoms

This study provides the influence of different heat exchanger internals (helical pipe coils, heating plugs, pipe registers) and reactor bottom shapes (torispherical/dished (Kloepper‐shape), hemispherical, and flat) on the flow field, the turbulent kinetic energy, and the ratio of tangential flow in stirred vessels, based on extensive stereo PIV measurement series in refractive index‐matched, optically completely accessible systems. The investigations impressively show advantages and disadvantages of the various equipment, which have a massive influence on both heat transport and the flow.     

热电厂烟气余热回收用于集中供热的系统形式及参数分析

目前我国燃煤热电厂在能源供应中的比例占到了40％以上,却很少回收大量烟气余热,尤其以供热为目标的余热回收项目更加少见,造成了严重的环境污染和能源浪费.文中对基于直接接触式换热和吸收式热泵技术的烟气余热梯级回收利用系统建立相应的数学模型,提出一种烟气余热回收用于集中供热的方案,探究影响该系统初投资的主要参数,分析了热网回...     

Influence of the structure of MgO·nAl2O3 spinel lattices on transparent ceramics processing and properties

It is demonstrated that a complete elimination of pores on sintering is governed not only by the size of the ceramic powder particles and by the homogeneity of their mutual coordination but similarly strongly by the state of the crystal lattice: with different cation disorder at fixed stoichiometry (n = 1) the sintering temperatures may differ by as much as 200 °C at constant powder particle size and equal homogeneity of the green bodies. Additionally, the impact of stoichiometry was investigated over the range between n = 1 and n = 3 with retarded reactive sintering at moderately increased Al₂O₃ concentrations but promoted densification of alumina-rich compositions. Taking advantage of the observed effects, sintered spinel ceramics were derived by reactive sintering of undoped MgO/Al₂O₃ mixtures resulting in an in-line transmittance which equals spinel single crystals of similar composition from 200 nm wave length up to the IR range.     

Enzymatically Modified Shea Butter and Palm Kernel Oil as Potential Lipid Drug Delivery Matrices

Drug formulations based on lipids can enable a significantly better delivery of a pharmaceutically active substance and thus enhance their bioavailability. However, natural fats and oils usually have properties, which do not allow their direct use for drug delivery. Therefore, we have modified palm kernel oil (PKO) and shea butter (SB) via lipase‐catalyzed transesterification using either glycerol – to create a diglyceride‐enriched lipid – or using hexanoic acid via acidolysis – to alter their fatty acid composition – and hence to improve drug solubility of Celecoxib serving as model compound. The most suitable enzyme was immobilized Thermomyces lanuginosus lipase (Novozyme TL IM). The solubility of Celecoxib as determined in SB, pharmaceutical grade SB, glycerol‐modified SB, hexanoic acid‐modified SB, PKO, glycerol‐modified PKO, and hexanoic acid‐modified PKO. Incorporation of one or two equivalents of hexanoic acid enabled higher Celecoxib solubilization than the diglyceride rich oil. Although structured SB and PKO (15.8 ± 0.4 mg mL^?1) do not differ significantly (p < 0.05) as per the amount of Celecoxib dissolved, the use of the modified oils enhanced Celecoxib solubility in SB (15.5 ± 1.3 mg mL^?1) in comparison to shea butter (7.9 ± 0.5 mg mL^?1). The lipase‐catalyzed modification also improved the miscibility of the oils with surfactants such as Tween 20 and resulted in reduced droplet sizes (<70 nm at oil/surfactant ratios of 1:2 and 1:1) and reduced polydispersity index values of the resulting emulsions. Practical Application: The structured triglycerides synthesized in this work on the basis of natural shea butter oils could function as suppository bases and oil phase in oral and parenteral lipid‐based formulations for improving the solubility and absorption of poorly soluble drugs. As various lipases with distinct selectivity are available for the enzymatic synthesis of structured triglycerides and useful for this purpose, further tailor‐designed formations should be accessible. With the aim of developing novel lipid drug delivery matrices palm kernel oil (PKO) and shea butter (SB) were modified via lipase‐catalyzed transesterification to alter their fatty acid composition and hence to improve drug solubility of the model compound Celecoxib. Incorporation of one or two equivalents of hexanoic acid enabled better Celecoxib solubilization than the diglyceride‐rich oil. Overall, the successful modification process yielded structured lipids with promising miscibility with selected surfactants and potential enhancement of Celecoxib solubility and thus represents a promising approach for the development of novel safe and effective lipid‐based delivery systems.

     

Silica Transfer in Ternary Rubber Blends: Calculation and Experimental Determination

A novel model is presented for predicting the phase selective filler localization in an equilibrium state for ternary rubber blends of SBR, NBR, and NR. It is based on surface tension data of the rubber components and the filler. Phase‐selective filler localization in ternary rubber blends is determined experimentally by means of FTIR spectroscopy on the basis of the wetting concept. It is found that by preparation of ternary blends with certain silica loadings, pre‐mixed in each blend phase using the masterbatch technology, silica transfer processes between blend phases take place until the equilibrium filler distribution is reached. The sequence of the silica transfer processes can be explained by taking into consideration the formation of a phase‐in‐phase morphology of the ternary blend.

     

Pentacycloundecane-diol-based HIV-1 protease inhibitors: biological screening, 2D NMR, and molecular simulation studies

Novel compounds incorporating a pentacycloundecane (PCU) diol moiety were designed, synthesized, and evaluated as inhibitors of the wild-type C-South African (C-SA) HIV-1 protease. Seven compounds are reported herein, three of which displayed IC(50) values in the 0.5-0.6 μM range. The cytotoxicity of PCU cage peptides toward human MT-4 cells appears to be several orders of magnitude less toxic than the current antiviral medications ritonavir and lopinavir. NMR studies based on the observed through-space (1)H,(1)H distances/contacts in the EASY-ROESY spectra of three of the considered PCU peptide inhibitors enabled us to describe their secondary solution structure. Conserved hydrogen bonding interactions were observed between the hydroxy group of the PCU diol inhibitors and the catalytic triad (Asp25, Ile26, Gly27) of HIV protease in docking and molecular dynamics simulations. The biological significance and possible mode of inhibition by PCU-based HIV protease inhibitors discussed herein facilitates a deeper understanding of this family of inhibitors and their potential application to a vast number of alternative diseases related to proteases.     

Subjective evaluation of natural high‐saturated images on a wide gamut display

In previous studies of image evaluation using wide color gamut displays, it is unclear to what degree people prefer the chroma‐varying images, especially the images that are more saturated than the most preferred image. Here, we present a study using a wide color gamut display, which measured viewers' most preferred level of image chroma (experiment 1) and their subjective evaluation of images that were less or more saturated than the previously most preferred one (experiment 2). The results showed that (a) the subjects' preferences for the original or for more saturated images depended on the images' original chroma and (b) the subjective evaluation of the images, that is, Valence and Arousal, did not deteriorate when the chroma of images increased more than the most preferred level. Such results indicate that the increase of the image chroma in wider color gamut displays can have a substantial influence on the impression images have on viewers.