Search

Aufgrund der Liberalisierung des EU-Zuckermarktes wird der Erh��hung der Ausbeute von Saccharose aus Zuckerr��ben in Form von Wei��zucker eine immer gr����ere Bedeutung bei der Optimierung des Produktionsprozesses zugerechnet. Es ist das Ziel dieser Arbeit, den Einfluss der verschiedenen Nichtsaccharosestoffe auf Kinetik und Thermodynamik von technischen Saccharosel��sungen besser zu verstehen und Methoden und Vorgehensweisen aufzuzeigen, mit welchen vorhandene Kristallisationsanlagen, insbesondere im sogenannten Nachproduktbereich der Zuckerfabrik, hinsichtlich der Leistungsf��higkeit und des vorhandenen Optimierungspotentials bewertet werden k��nnen. Hierf��r werden zun��chst die in der Zuckertechnologie gel��ufigen Berechnungsmethoden zum Erhalt der f��r die Kristallisation wichtigen Stoff- und Prozessgr����en kritisch hinterfragt und allgemein g��ltigen physikalisch-chemischen Grundgleichungen gegen��bergestellt. Auch die gel��ufigen analytischen Methoden der praktischen Betriebskontrolle werden einer kritischen Betrachtung unterzogen. Es werden verbesserte Methoden pr��sentiert, mit welchen es m��glich ist, L��slichkeitsdaten und Kristallisationsgeschwindigkeiten von Saccharose in technischen L��sungen experimentell zu bestimmen. Die L��slichkeit von technischen L��sungen, welche w��hrend der zwei Zuckerr��benkampagnen 2018/2019 und 2019/2020 aus Fabriken verschiedener europ��ischer L��nder genommen wurden, werden zusammen mit einer ausf��hrlichen Analyse der Nichtsaccharosezusammensetzung dargestellt. Es wird untersucht, welche Nichtsaccharosestoffe f��r eine erh��hte oder verringerte Saccharosel��slichkeit in technischen L��sungen verantwortlich sind. Weiter wird untersucht, ob die Kristallisationsgeschwindigkeit von technischen L��sungen mit einem nat��rlichen hohen pH-Wert sich aufgrund des hohen pH-Werts ver��ndert, beziehungsweise, ob durch eine Konditionierung des pH-Werts der technischen L��sungen eine Ver��nderung der Kristallwachstumsgeschwindigkeit in diesen L��sungen zu erreichen ist., The EU sugar market liberalization shifts the goal of the process optimization more and more towards an increase of the white sugar yield and a minimization of the sugar loss in the sugar beet. The aim of this work is to deliver a better understanding of the influence of non-sugar substances on the kinetics and thermodynamics of technical sucrose solutions and to provide methods and instructions to evaluate the performance and to find optimization potential of existing crystallization plants, especially in the so called after-product strike of the sugar factory. The commonly used mathematical methods of the sugar technology to compute the necessary process data for the sucrose crystallization are critically scrutinized and compared to generally valid basic physical and chemical equations. The common analytical methods of practical operational control are also subjected to this evaluation. This work presents improved methods to determine solubility data and crystallization rates of sucrose in technical solutions. The solubility of technical solutions which were taken during the two sugar beet campaigns 2018/2019 and 2019/2020 from factories in different European countries are presented together with a detailed analysis of the non-sucrose composition of these solutions. The non-sucrose substances responsible for increased or decreased sucrose solubility in technical solutions are investigated. Furthermore, it is examined whether the crystallization rate of technical solutions with a high natural pH value is slowed down due to the high pH value and whether it is possible to change the crystal growth rate in these solutions by conditioning the pH value.

In den zurückliegenden Dekaden nahm die Herstellung nachhaltiger, pharmazeutischer Wertstoffe sowohl aus Pflanzen (engl.: Botanicals) als auch tierischen Zellkulturen (engl.:Biologicals) stark zu. Um aus diesen Ausgangsmaterialien den gewünschten Zielstoff zu isolieren, sind komplexe Prozessketten notwendig, die ein großes finanzielles Optimierungspotential bieten. In dieser Arbeit werden Optimierung zweier unterschiedlicher Prozessschritte durch systematische Prozessauslegung und die Erstellung von dynamischen Prozessmodellen vollzogen. Die Modelle müssen hierbei in der Lage sein alle auftretenden Effekte abzubilden. Weiterhin müssen Modelle einerseits modular vorliegen, um eine Übertragbarkeit zu anderen Systemen zu vereinfachen, und andererseits müssen die Modellparameter mit möglichst wenig Versuchen zu bestimmen sein. Für biologische Prozesse wird eine kontinuierliche Ultrafiltration betrachtet. Diese war lange das Bottleneck für kontinuierliche Bioprozesse und bietet daher ein großes Optimierungspotential. Bei der Modellerstellung wurde hierbei explizit auf die geometrischen Eigenschaften einer kontinuierlichen Ultrafiltration eingegangen. Untersucht wurden in dieser Arbeit die Aufkonzentrierung einer niedrigkonzentrierten Proteinlösung eines monoklonalen Antikörpers sowie einer hochkonzentrierten Serumalbumin-Lösung. Als Gegenstück wurde die absatzweise durchgeführte Kristallisation mit dem Zielstoff Artemisinin betrachtet. Ziel für diese war die Entwicklung eines definierten Prozesses, bei dem neben der Ausbeute auch die Partikelgröße anpassbar sein sollen. Weiterhin galt zu klären, ob der Kristallisationsschritt zu einem früheren Zeitpunkt im Prozess gewinnbringend eingesetzt werden kann und dadurch ein verkürzter, kostengünstigerer Herstellungsweg möglich ist. Für beide Grundoperationen werden schrittweise Prozesse entwickelt und die Parameterbestimmung für die Prozessmodelle dargestellt. Die Modelle wurden im Anschluss validiert und im Falle der Ultrafiltration wird eine modellbasierte Optimierung durchgeführt. Die durchgeführten Arbeiten verdeutlichen, dass eine Prozessmodellierung umso einfacher und gewinnbringender ist, je mehr Variablen inline messbar sind., In the past decades, the production of sustainable, valuable pharmaceutical substances from both plants (botanicals) and animal cell cultures (biologicals) has increased significantly. In order to isolate the desired target substance from these starting materials, complex process chains are necessary, which offer a large financial optimization potential. This work presents optimization of two different unit operations by systematic process design and the creation of dynamic process models. The models must be able to represent all occurring effects. Furthermore, models have to be modular in order to simplify transferability to other systems and the model parameters have to be determined with as few experiments as possible. For biological processes, continuous ultrafiltration is considered. This has long been the bottleneck for continuous bioprocesses and therefore offers great potential for optimization. The geometric properties of continuous ultrafiltration were explicitly considered in the model development. The concentration of a low-concentration protein solution of a monoclonal antibody and a high-concentration serum albumin solution were investigated in this work. As a counterpart, the batch crystallization with Artemisinin as target component was investigated. The aim for this was to develop a defined process in which, the particle size should also be adjustable not just yield. Furthermore, it had to be clarified whether the crystallization step can be profitably applied earlier in the process. This would result in ashortened, more cost-effective way to isolate Artemisinin. Botch Processes were developed step by step and the parameter determination for the process models was presented. The models were subsequently validated and in the case of ultrafiltration a model-based optimization was performed. The work illustrates that the more variables can be measured inline, the simpler and more profitable process modeling becomes.

Gedruckt erschienen im Unviversitätsverlag der TU Berlin, ISBN 978-3-7983-3139-6 (ISSN 0174-4003), Aufgrund der deutlich unterschiedlichen Verarbeitungsbereiche von Polyhydroxybutyrat (PHB) und Polyamid 6 (PA 6) ist die gemeinsame Verarbeitung der beiden Polymere eine verfahrenstechnische Herausforderung. Um die Verträglichkeit und Prozessfähigkeit der PA 6-PHB-Blends beurteilen zu können, wurde somit zunächst ein geeigneter Aufbereitungsprozess auf einem Doppelschneckenextruder entwickelt. Zudem erfolgte die Herstellung von maleierten PHB (C) als Verträglichkeitsvermittler. An zwei- und dreikomponentigen Blends konnte gezeigt werden, dass die Herstellung der Blends möglich ist, diese jedoch zu ausgeprägter Koaleszenz neigen. Die C-Typen bewirken zwar teilweise eine Verfeinerung der Morphologie, vermeiden die Koaleszenz jedoch nicht effektiv. Durch rasterkraftmikroskopische Aufnahmen und mechanische Untersuchungen kann allerdings eine begrenzte Kompatibilisierwirkung nachgewiesen werden. Zudem wird deutlich, dass ein synergistischer Versteifungseffekt zu erhöhten Zugmoduln der Blends führt. Hierdurch werden im spritztrockenen Zustand bis zu 131% des reinen PA 6-Wertes und nach der Konditionierung 151% erreicht. Mittels dynamischer Differenzkalorimetrie und Fourier-Transformations-Infrarotspektroskopie konnte der Effekt auf die Erhöhung der Kristallinität zurückgeführt werden., Due to the significantly different processing ranges of polyhydroxybutyrate (PHB) and polyamide 6 (PA 6), the combined processing of the two polymers is a process engineering challenge. In order to assess the compatibility and processability of the PA 6-PHB blends, a suitable compounding process was therefore first developed on a twin-screw extruder. In addition, the production of maleated PHB (C) as a compatibilizer was carried out. It could be shown on two- and three-component blends that it is possible to produce the blends, but that they tend to have a pronounced coalescence. Although the C-types partially refine the morphology, they do not effectively prevent coalescence. However, a limited compatibility effect can be demonstrated by atomic force microscopic images and mechanical examinations. Furthermore, a synergistic stiffening effect leads to increased tensile moduli of the blends. This results in up to 131% of the pure PA 6 value in the dry-as-mould state and 151% after conditioning. Using dynamic differential calorimetry and Fourier transform infrared spectroscopy, the effect could be attributed to the increase in crystallinity.

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2020; Aachen : RWTH Aachen University 1 Online-Ressource : Illustrationen, Diagramme (2020). = Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2020, The integration of simulation tools in the development of crystallization processes represents a great potential for reducing costs and time. Currently the use of detailed simulation tools is low, reasons are low transferability and predictiveness of commercially available tools. The goal of this work is to improve transferability and predictivity by extension of the sequential determination of parameters and the integration of crystal morphology. Based on the two example systems itaconic acid and oxalic acid the added value by integration of crystal morphology to the transferability is shown. In the first part, the simulations parameters of the chosen time-driven n-Monte Carlo approach are determined for the selected kinetic models from literature. An extension of the approach is introduced which improves the simulation parameters, the number of representative crystals and the time step size. Thereby the overall simulation time is reduced. On the basis of the specified simulation parameters, the kinetic model parameters of breakage, growth, agglomeration and nucleation are determined for itaconic acid and oxalic acid. For the determination of the kinetic parameters, experiments were carried out according to the extended sequential scheme. It shows that the crystallization of itaconic acid using the one-dimensional model of the crystalphase is well described. However, the one-dimensional simulation of oxalic acid discloses strong differences between experiment and simulation. The reason for this is the significantly more pronounced deviation of the stationary crystal shape from the one-dimensional shape. This motivates the integration of the morphology to gain higher transferability and applicability. For the integration of the morphology the implementation and the necessary accuracy in the calculation of crystal morphology is studied. The impact of the morphology on the implemented kinetic rates is shown and the integration of the morphology is realized. The morphological model is then used to simulate itaconic acid and oxalic acid. For oxalic acid the kinetic breakage parameter is adjusted. Finally, the improved results by morphological simulation of oxalic acid is shown in comparison to one-dimensional simulation and experimental data., Published by RWTH Aachen University, Aachen

Die hier beschriebene Arbeit befasst sich mit der Konstruktion und dem wissenschaftlichen Einsatz eines Reaktorsetups zur Analyse chemischer Reaktionen unter solvothermalen Bedingungen anhand röntgenbasierter Analysemethoden bis zu einer Maximaltemperatur von 180 °C. Der Reaktor basiert dabei auf kommerziell erhältlichen Reaktionsgefäßen (Vmax = 5 und 10 ml), die sich bereits in Synthesen in Laborumgebungen etabliert haben. Neben den Reaktionsgefäßen, die eine Operation nah an Laborbedingungen gestatten, wurde das Setup konzipiert mit einem Fokus auf die parallele Analyse chemischer Reaktionen mit mehreren Methoden. Die Einbindungen der Möglichkeiten Flüssigkeiten und Feststoffe während der Reaktion hinzudosieren, gestatten dabei eine breite Anwendbarkeit für eine Vielzahl unterschiedlicher experimenteller Aufgabestellungen. Nach der initialen Testphase wurde das Reaktorsetup für eine Reihe von Untersuchungen im Bereich von Reaktionen Koordinationspolymere eingesetzt und dabei zugrundeliegende Reaktionskinetiken und –mechanismen untersucht. Dabei wurden die der Kristallisation von CAU-15-cit ([Al2(OH)4(O2C-C3H4-CO2)]· n H2O) zugrundeliegenden Mechanismen untersucht. In einer weiteren Studie wurde die sukzessive Zersetzung und Umwandlung der Verbindung Ce-DUT-67 ([Ce6(μ3 O)4(μ3-OH)4(PZDC)4(OH)4(H2O)4], mit PZDC2- = 3,5-Pyrazoldicarboxylat) zu Cer(III)formiat ([Ce(O2CH)3]) untersucht. Darüber hinaus wurde die Umwandlung von UTSA 74 ([Zn2(dobdc)(G)2], mit dobdc4- = 2,5-Dihydroxiterephthalat und G = koordiniertes Gastmolekül) unter wässrigen Bedingungen und folgender Bildung von MOF-74 ([Zn2(dobdc)(G)2], mit dobdc4- = 2,5-Dihydroxiterephthalat und G = koordiniertes Gastmolekül) analysiert. In einer kombinierten XRD/XAS Untersuchung an einem Palladiumkatalysator, der auf Cr-MIL-101und Cr-MIL-88B immobilisiert eingesetzt wurde, konnte die Evolution des Katalysators während einer Heck-Kupplungsreaktion verfolgt werden. This thesis deals with the construction and application of a reactor setup aimed at the analysis of chemical reactions under solvothermal conditions. Regarding accessible reaction conditions, the reactor features a maximum temperature of 180 °C and is designed for the analysis of chemical reactions using X-ray based characterization techniques. The reactor is based on commercially available reaction vessels of two sizes (Vmax = 5 und 10 ml) that have already been well established in common laboratory practice. In addition to these reaction vessels that enable experiments close to laboratory conditions, the setup has been designed with a focus on the parallel analysis of reactions with multiple analysis methods. Furthermore, the incorporation of a solid and a liquid dosing system to change chemical parameters during the experiment enables its use for a broad spectrum of scientific questions. After an initial test phase, the reactor setup was employed in a variety of different studies involving coordination polymers (and metal-organic frameworks) to determine underlying reaction kinetics and reaction mechanisms. In the course of these studies the crystallization mechanisms underlying the formation of a new compound denoted CAU-15-cit ([Al2(OH)4(O2C-C3H4-CO2)]· n H2O) were studied. In an additional study the decomposition and subsequent transformation of Ce-DUT-67 ([Ce6(μ3 O)4(μ3-OH)4(PZDC)4(OH)4(H2O)4], with PZDC2- = 3,5-pyrazoledicarboxylate) to Ce(III)formiate ([Ce(O2CH)3]) was analysed. Furthermore, the conversion of UTSA-74 ([Zn2(dobdc)(G)2], with dobdc4- = 2,5-dihydroxiterephthalate and G = coordinated guest molecule) to its polymorph MOF-74 ([Zn2(dobdc)(G)2], with dobdc4- = 2,5-dihydroxiterephthalate and G = coordinated guest molecule) in aqueous medium was studied. In a combined XAS/XRD study on a palladium catalyst immobilized on Cr-MIL-101 and Cr-MIL-88B the evolution of the palladium catalyst was followed during a Heck coupling reaction.

Polylactide (PLA) is known as one of the most promising biopolymers as it is derived from renewable feedstock and can be biodegraded. During the last two decades, it moved more and more into the focus of scientific research and industrial use. It is even considered as a suitable replacement for standard petroleum-based polymers, such as polystyrene (PS), which can be found in a wide range of applications—amongst others in foams for packaging and insulation applications—but cause strong environmental issues. PLA has comparable mechanical properties to PS. However, the lack of melt strength is often referred to as a drawback for most foaming processes. One way to overcome this issue is the incorporation of chemical modifiers which can induce chain extension, branching, or cross-linking. As such, a wide variety of substances were studied in the literature. This work should give an overview of the most commonly used chemical modifiers and their effects on rheological, thermal, and foaming behavior. Therefore, this review article summarizes the research conducted on neat and chemically modified PLA foamed with the conventional foaming methods (i.e., batch foaming, foam extrusion, foam injection molding, and bead foaming).

Polymere finden vielfältigen Einsatz im Alltag sowie in Wissenschaft, Industrie und Technik. Ihre makroskopischen Eigenschaften abhängig von ihrer Verarbeitung zu untersuchen ist elementarer Bestandteil der Polymerforschung. Ein Großteil der Polymere kristallisiert bei Abkühlung und nimmt dann eine teilkristalline Struktur an. Die Ausbildung dieser Struktur ist von den Kristallisationsbedingungen und vom Vorhandensein intrakristalliner Mobilität abhängig. Es wurden sowohl der Einfluss der Dynamik der nach Kristallisation verbleibenden amorphen Phase auf die Strukturbildung, als auch der, der intrakristallinen Dynamik untersucht. Es ließen sich charakteristische Unterschiede bei der Ausbildung der finalen Struktur feststellen und es wurde der Versuch unternommen, aus diesen ein Kristallisationsmodell für Polymerschmelzen zu entwickeln., Polymers are used in a wide variety of applications in everyday life as well as in science, industry and technology. The investigation of their macroscopic properties depending on their processing is an elementary component of polymer research. Most of polymers crystallize on cooling and possess a semi-crystalline structure thereafter. The formation of this structure depends on the crystallization conditions and the presence of intra-crystalline mobility. The influence of the dynamics of the amorphous phase remaining after crystallization on the structure formation as well as intracrystalline dynamics were investigated. Characteristic differences in the formation of the final structure could be determined and an attempt was made to develop a crystallization model for polymer melts from these.

Non-invasive imaging modalities are used for the morphological and functional evaluation and diagnosis of gout; however, none of these methods are sufficiently sensitive or specific for the diagnosis of gout. By the use of dual-energy computed tomography (DECT) the direct visualization of sodium urate deposition is now possible. Moreover, it is possible to show the different pathological situations, disease activity and monitoring of tophaceous gout. The positive DECT scan became one of the 2015 ACR/EULAR classification criteria for gout 2 years ago.The literature search from 2009-2017 in PubMed, with the search criteria "Dual Energy CT and Gout" revealed 77 publications on the DECT method.The DECT technique has a high sensitivity (90-100%) and a high specificity (83-89%) for diagnosing gout. The development of a semiquantitative scoring method also enables measurement of the severity of urate deposits at specific sites.The gold standard for the diagnosis of gout is still the detection of monosodium urate monohydrate crystals by polarizing microscopy after a joint punction; however with the DECT it is possible to non-invasively visualize, measure and score urate deposition and is therefore suitable for estimating the severity and prognosis. Although not clinical validated, DECT may sometimes help to detect gout. More studies should be conducted.

Dissertation, RWTH Aachen University, 2017; Jülich : Forschungszentrum Jülich GmbH, Schriften des Forschungszentrums Jülich : Reihe Energie & Umwelt, 393, 1 Online-Ressource (168 Seiten) : Illustrationen (2017). = Dissertation, RWTH Aachen University, 2017, Numerous technical applications in the energy and metallurgical industries demand a fundamental knowledge of the flow of slags. In particular, the operation of an entrained flow gasifier is challenging as the slag has to be reliably discharged. The slag consists of unburned inorganic matter, usually oxides. Crystallization in this oxide melt influences the flow behavior of the slag because of the occurring precipitates. In this study the mechanisms and impact of crystallization on the flow of oxide slags were investigated. For this purpose, isothermal viscosity measurements were conducted on fossil and renewable solid fuel slags in order to examine the rheological evolution over time caused by the crystallization. It has been demonstrated that the evolution of viscosity of a sub-liquidus melt depends strongly on time, as well as on temperature and composition. Using a rotational high-temperature viscometer, it was found that the crystallization during flow could be separated into three time regimes: a lag-time, in which the undercooled melt behaved as an Arrhenius-liquid; the kinetic-driven crystallization accompanied by an increase of the viscosity; and, finally, the rheological equilibrium that is represented by a constant viscosity. Furthermore, an increase of viscosity caused by crystallization was accompanied by a shift from Newtonian to non-Newtonian flow; here, shear thinning flow indicated the existence of precipitates. SEM was used to examine the crystalline precipitates. The evolution of flow was used to create time-temperature-transformation diagrams. It was observed that an increase of the degree of supercooling decreases the incubation as well as the crystallization period. The crystallization of the oxide melt follows the classical theory of crystallization. Moreover, it was shown that the change of viscosity might be used as morphological information to describe kinetic parameters. The conclusions from the experimental results regarding the influence of crystallization on the flow of oxide melts were transferred to an empirical model. The model considers the physical influence of the crystals and the chemical change of the bulk composition caused by the crystallization. Therefore, the concept of the resulting relative viscosity was introduced, in order to describe the physical and chemical effects of crystallization. The evolution of viscosity from the metastable to the equilibrium state was described by a kinetic theory. The results of the model correlate well with the experimental observations., Published by Forschungszentrum Jülich GmbH, Jülich

Cristal deposit disorders are characterised by cristal deposits in hyaline and fibrocartilage, in synovium, capsule, ligaments and tendons and periarticular soft tissue. Calciumpyrophosphatedihydrate (CPPD), hydroxyapatite (calcific tendinitis) and uric acid arthropathies are the most common cristal deposit diseases. Radiography is still the number one image modality for initial imaging and the identification of cristal-induced inflammatory arthropathies. Differentiation between the entities of cristal deposit arthropathies can be challenging. Clincial and radiological findings may overlap in different cristal deposit arthropathies, owing a certain diagnosis difficult.

Detritic synovitis represents a common finding in routine orthopedic pathology. Microscopically, the synovium displays cartilaginous and bony fragments in the synoviocyte layer or within the subsynovial soft tissues associated with resorptive changes. In the vast majority of cases, detritic synovitis is associated with conditions leading to the destruction of articular cartilage and subchondral bone, such as severe osteoarthritis, collapsed avascular necrosis, diabetes mellitus, Charcot arthropathy or non-union fractures. The objective of this article is to review the literature regarding the microscopic findings in ochronosis, rapidly destructive hip disease and apatite crystal depositions that can enable a confident diagnosis or a limited differential diagnosis of detritic synovitis.

Urinary composition is the result of the interplay of all metabolic processes, including all metabolites and toxins produced. Any change in urine composition influences urinary supersaturation, the major thermodynamic driving force of crystal formation. Urolithiasis is a wide-spread disease with a prevalence rate of 4% to 10%. Formation risk of calcium-oxalate, by far the most common mineral in uroliths, is quantified by the Bonn-Risk-Index (BRI). The BRI measures induced crystal growth within native urine and shows superior diagnostic sensitivity and specificity compared to other urolithiasis risk indices. The concept of BRI quick test presented in this work allowes even untrained persons to easily determine the urolithiasis risk. Many diseases lack a simple, easily accessible and cost effective diagnostic approach to monitor their course and treatment success. Since BRI takes into account every constituent of native urine, it can be used to monitor a wide range of metabolic diseases.

If acute arthritis occurs in the elderly in addition to typical degenerative, load-related joint complaints, this is often induced by crystal deposition. The crystals lead to activation of the immune system resulting in acute inflammation. In addition to gout, calcium pyrophosphate deposition (CPPD) disease in particular must also be taken into consideration. Diagnostically important are imaging techniques, e.g. early specific alterations of cartilage can be shown by joint sonography and later calcium pyrophosphate crystals can be detected as cartilage calcification (chondrocalcinosis) by radiography. Important for the diagnosis of crystal arthropathy is usually the microscopic detection of specific crystals in the synovial fluid and is supported by exclusion of septic arthritis by arthrocentesis. In contrast to gout, which can be well controlled by the pharmaceutical lowering of uric acid levels, there is no causal therapy for CPPD disease so far. As CPPD may occur as a secondary effect in metabolic disorders, such as hyperparathyroidism or hemochromatosis, it seems to be important to search for the underlying disease. The following article presents the current knowledge on clinically relevant aspects of the pathogenesis, diagnosis and therapy of CPPD disease.