Industrielle Kristallisation – Moderne großtechnische Anlagen und Fallstudien

Industrial crystallization – Modern industrial plants and case studies . In the field of mass crystallization a number of advanced plant designs have been implemented in the past decade, and are exemplified in the crystallization of adipic acid and common salt, and in evaporation of aluminate liquor which is susceptible to encrustation. Assessment criteria are, inter alia, product qualities such as the purity achieved and the crystal size distribution, and operation parameters such as the duration of process flow and control behaviour. The significant increase in quality is largely attributable to the crystallizers, which have been optimized above all with regard to the crystal-size distribution and the duration of product flow.     

Umsetzung von Dihydroxyaceton mit Methylammoniumacetat Untersuchungen zur Maillard-Reaktion, X

Zusammenfassung Dihydroxyaceton reagiert mit Methylammoniumacetat in wäßriger Lösung beim Erhitzen rasch unter Bräunung. Von den mit Methylenchlorid extrahierbaren Produkten konnten die heterocyclischen Verbindungen 1 bis 30 isoliert und größtenteils identifiziert werden.

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Reaction of dihydroxyacetone with methylammoniumacetate studies on the Maillard-Reaction, X

Summary By heating dihydroxyacetone and methylammoniumacetate in aqueous solution, a deeply brown coloured reaction mixture is obtained. The products extractable with methylenechlorid were separated. Several heterocyclic compounds (1–30) could be identified.

     

Fourier transform infrared detection in miniaturized total analysis systems for sucrose analysis

In this work, a flow system containing a micromachined lamella-type porous silicon reactor and a novel mid-IR fiber-optic flow cell were used for the enzymatic determination of sucrose in aqueous solution. The method relies on the enzymatic hydrolysis of sucrose to fructose and glucose catalyzed by β-fructosidase and on the acquisition of FT-IR spectra before and after complete reaction. β-Fructosidase was covalently bound to the porous silicon surface of the channels in the microreactor. The porous silicon was achieved by anodization of the silicon reactor in a HF/ethanol mixture. For the measurement of small amounts of aqueous solution, a miniaturized flow cell was developed which consisted of two AgCl(x)Br(1)(-)(x) fiber tips (diameter, 0.75 mm) coaxially mounted in a PTFE block at a distance of 23 μm. The flowing stream was directed through the gap of the two fiber tips which served to define the optical path length and to bring the focused mid-IR radiation to the place of measurement. Using this construction, a probed volume of ～10 nL was obtained. The calibration curve was linear between 10 and 100 mmol/L sucrose. Furthermore, the potential of this method was demonstrated by the analysis of binary sucrose/glucose mixtures showing no interference from glucose and by the successful determination of sucrose in real samples.     

Pond and Irrigation Model (PIM): a Tool for Simultaneously Evaluating Pond Water Availability and Crop Irrigation Demand

Agricultural ponds are an important alternative source of water for crop irrigation to conserve surface and ground water resources. In recent years more such ponds have been constructed in Mississippi and around the world. There is currently, however, a lack of a tool to simultaneously estimate crop irrigation demand and pond water availability. In this study, a Pond-Irrigation Model (PIM) was developed to meet this need using STELLA (Structural Thinking, Experiential Learning Laboratory with Animation) software. PIM simulated crop land and agricultural pond hydrological processes such as surface runoff, soil drainage, and evapotranspiration as well as crop irrigation demand and pond water availability. More importantly, PIM was able to decide when to conduct crop irrigation based on management allowable depletion (MAD) root zone soil water content and to determine optimal ratios of agricultural pond size to crop land with sufficient pond water available for crop irrigation. As a case demonstration, the model was applied to concomitantly estimate row crops (i.e., corn, cotton, and soybeans) water irrigation demand and pond water availability in a farm located at East-central Mississippi. Simulations revealed that corn used more soil water for growth than soybeans, whereas soybeans needed more irrigation water than corn and occurred due to less rainwater available for soybeans growth. We also found that there was one time for corn, zero time for cotton, and two times for soybeans when the pond water level was drawn to near zero for irrigation from 2005 to 2014. PIM developed in this study is a useful tool for estimating crop irrigation demand and pond water availability simultaneously.     

Data workflow to incorporate thermodynamic energies from Calphad databases into grand-potential-based phase-field models

Journal of Materials Science - In order to approximate Gibbs energy functions, a semi-automated framework is introduced for binary and ternary material systems, using Calphad databases. To generate...     

Zur qualitativen Theorie gleichstromvormagnetisierter Eisendrosseln

Zusammenfassung und Schluß An Hand einer idealisierten Magnetisierungskurve, aus mathematischen Gründen durch den Hyperbelsinus dargestellt, wird für erzwungene sinusförmige Induktionsänderung der zugehörige Feldstärkeverlauf einer gleichstromvormagnetisierten Eisendrossel abgeleitet. Es wird gezeigt, daß eine magnetische Gleichrichtung auftritt und deren Größe und Wirkung dargelegt. Die bekannten Regelkurven, sowohl für die Grundwelle der Feldstärke als auch ihren Effektivwert, werden ermittelt und besprochen. Da das Ergebnis in Form einer Fourierreihe erscheint, können auch alle Oberwellenfragen sofort übersehen werden. In diesem Zusammenhange wird insbesondere auf den Einfluß der Polarität der Vormagnetisierung und auf die Wirkung von Induktionsoberwellen hingewiesen, mit deren Hilfe bekanntlich einzelne Feldstärkeoberwellen unterdrückt werden können.Die obigen Ausführungen stellen einen Versuch dar, einen Teil der Aufgaben, und zwar den Grenzfall für erzwungene sinusförmige Spannung an der Drossel in einphasiger Schaltung, mathematisch zu beschreiben. Der andere Grenzfall für erzwungenen sinusförmigen Strom, sowie das Zusammenwirken derartiger Drosseln in mehrphasigen Schaltungen soll späteren Mitteilungen vorbehalten bleiben.     

A Peroxygenase from Chaetomium globosum Catalyzes the Selective Oxygenation of Testosterone

Unspecific peroxygenases (UPO, EC 1.11.2.1) secreted by fungi open an efficient way to selectively oxyfunctionalize diverse organic substrates, including less‐activated hydrocarbons, by transferring peroxide‐borne oxygen. We investigated a cell‐free approach to incorporate epoxy and hydroxyl functionalities directly into the bulky molecule testosterone by a novel unspecific peroxygenase (UPO) that is produced by the ascomycetous fungus Chaetomium globosum in a complex medium rich in carbon and nitrogen. Purification by fast protein liquid chromatography revealed two enzyme fractions with the same molecular mass (36 kDa) and with specific activity of 4.4 to 12 U mg^?1. Although the well‐known UPOs of Agrocybe aegerita (AaeUPO) and Marasmius rotula (MroUPO) failed to convert testosterone in a comparative study, the UPO of C. globosum (CglUPO) accepted testosterone as substrate and converted it with total turnover number (TTN) of up to 7000 into two oxygenated products: the 4,5‐epoxide of testosterone in β‐configuration and 16α‐hydroxytestosterone. The reaction performed on a 100 mg scale resulted in the formation of about 90 % of the epoxide and 10 % of the hydroxylation product, both of which could be isolated with purities above 96 %. Thus, CglUPO is a promising biocatalyst for the oxyfunctionalization of bulky steroids and it will be a useful tool for the synthesis of pharmaceutically relevant steroidal molecules.