bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aufarbeitung von Plasmid‐DNA für Gentherapie und genetische Impfung
Authors: Voß C. 
Published: May 2008

AbstractPlasmid‐DNA wird als Klonierungsvektor zum Einbringen rekombinanter Gene in Mikroorganismen genutzt. Seit den 1990er Jahren wird dieses Prinzip auch zur Übertragung therapeutischer Gene in der Gentherapie und der genetischen Impfung verwendet. Diese Form der nicht viralen Gentherapie stellt eine deutlich risikoärmere Variante im Vergleich zur viralen Gentherapie dar. Zur Deckung des Bedarfs an Plasmid‐DNA in klinischen Studien und für in Zukunft zugelassene Therapeutika sind Produktionsverfahren erforderlich, die eine Herstellung im Multigramm‐ bis Kilogramm‐Maßstab möglich machen. Besondere Hersausforderungen werden hier im Bereich des Zellaufschlusses, der Abtrennung strukturell verwandter Verbindungen und der Prozess‐ und Produktanalytik gestellt. Dieser Übersichtsbeitrag fasst die Entwicklungen der letzten Jahre zusammen.
Verfahrens‐ und Katalysatordesign als Aufarbeitungsstrategie für die enzymatische Darstellung von Isomaltose
Authors: Jördening H.‐J. , Erhardt F. A. , Holtkamp M. , Buchholz K. , Scholl S. 
Published: May 2008

AbstractEs wird die Optimierung der Isomaltoseproduktion durch ein System aus enzymkatalysierter Reaktion und Adsorption des Produkts untersucht. Dafür wurden die Reaktionsbedingungen, die Biokatalysatoreigenschaften sowie die reaktionsintegrierte Abtrennung des Produkts eingehend geprüft. Ausgehend von immobilisierter Dextransucrase als Biokatalysator konnte durch Entwicklung von Coimmobilisaten ein deutlicher Fortschritt erzielt werden. Das beste Ergebnis ließ sich mit einer genetisch modifizierten Dextransucrase (GTFR) erhalten, wodurch die integrierte Abtrennung des Produkts bedeutend erleichtert wird. Der Gesamtprozess aus Biokatalyse und Adsorption für die verschiedenen Modifikationen wurde durch Berechnung der Prozesseffizienzen evaluiert.
Neue Entwicklungen auf dem Gebiet der simulierten Gegenstromchromatographie
Authors: Seidel‐Morgenstern A. , Keßler L. C. , Kaspereit M. 
Published: May 2008

AbstractChromatographische Trennverfahren besitzen eine außerordentliche Bedeutung bei der Aufreinigung wertvoller Stoffe im Bereich der pharmazeutischen Industrie, der Biotechnologie und bei der Gewinnung von Feinchemikalien. Typischerweise basieren die Prozesse nach wie vor auf dem Einsatz einer chargenweisen periodischen Injektion der Rohgemische und einer entsprechenden periodischen Sammlung der Produktfraktionen. In den 1960er Jahren wurde als leistungsstarke Alternative die auf einer Reihenschaltung von mehreren Trennsäulen basierende und einen Gegenstrom zwischen stationärer und mobiler Phase ausnutzende kontinuierliche Chromatographie entwickelt, die zunächst mit großem Erfolg in der Petrochemie und in der Zuckerindustrie zum Einsatz kam. In den letzten Jahren hat die so genannte Simulated Moving Bed (SMB)‐Chromatographie zunehmend Eingang in die pharmazeutische Industrie gefunden. Insbesondere Enantiomerentrennungen unter Verwendung chiraler stationärer Phasen sind zurzeit eine starke Triebfeder für die Entwicklung neuer und noch leistungsfähigerer Prozessvarianten. Gegenwärtig wächst auch auf Grund des steigenden Interesses an effizienten Methoden zur Aufarbeitung von Biomolekülen der Bedarf an leistungsstarken chromatographischen Verfahren. In diesem Aufsatz wird ein Überblick über neue Vorschläge und Trends auf dem Gebiet der kontinuierlichen Gegenstromchromatographie gegeben.
Perspektiven der Biothermodynamik – I. Thermostatik und Thermodynamik irreversibler Prozesse
Authors: Keller Jürgen U. 
Published: May 2008

AbstractDie Anwendung von Begriffen und Methoden der Thermodynamik der Gleichgewichte und der Vorgänge auf Systeme und Prozesse der Biotechnologie hat zur Bildung eines neuen Fachgebietes geführt, der Technischen Biothermodynamik. Der vorliegende Artikel soll der erste einer Reihe sein, in der versucht wird, einen Überblick über die Grundlagen und Möglichkeiten zu geben, die dieses Gebiet dem Verfahrensingenieur eröffnet, und dies auch an einzelnen Beispielen zu demonstrieren. Nach einigen einführenden Bemerkungen werden im vorliegenden Artikel die Grundbegriffe und die Hauptsätze der Thermodynamik für fluide Vielstoffsysteme mit inneren Variablen formuliert. Diese Systeme dienen als Modelle für Biofluide und andere Systeme der Biotechnologie. Danach wird der Formalismus der Thermodynamik irreversibler Prozesse an einem elementaren technischen Beispiel erläutert. In den folgenden Teilen sollen Anwendungen der Thermodynamik auf eine Reihe biochemischer und biotechnischer Systeme diskutiert werden, darunter auch biochemische Moleküle, wie sie in biologischen Membranen auftreten, und vor allem Proteine. Die Themen dieser Beiträge werden sein: Adsorption von Proteinen an festen Oberflächen, Hydratisierung, thermische Stabilität und Aggregation von Proteinen, thermodynamische Modelle des Stoffwechsels in Bakterien sowie Bioreaktoren und Fermenter.
Use of non‐mechanical valves at high temperature—A case study
Authors: Geldart D. 
Published: May 2008

AbstractNon‐mechanical valves are useful devices for controlling the flow of granular solids using only injected. Gas several types of such devices have been described in the literature. In this paper the consequences of using an incorrectly designed L‐valve to move very hot coarse solids from a fluidized bed calciner to a fluidized bed cooler and the steps taken to remedy the situation are described.
Inlet effect on the coal pyrolysis to acetylene in a hydrogen plasma downer reactor
Authors: Cheng Y. , Chen J. Q. , Ding Y. L. , Xiong X. Y. , Jin Y. 
Published: May 2008

AbstractCoal pyrolysis to acetylene in hydrogen plasma is a clean process for the coal utilization. A gas–solid downer reactor was employed to facilitate the high temperature reactions of coal pyrolysis in milliseconds. The effect of the inlet design on the coal injection was studied using CFD simulations, which were qualitatively compared with the cold model experiments in the prototype of a 2 MW hydrogen plasma reactor. The results revealed that the distribution of the coal particles near the inlet nozzles was significantly influenced by the layout of the flat‐shaped nozzles and the operating conditions. Accordingly the heating efficiency of the particles by the hot gas showed strong dependence on the inlet design. The hot model tests demonstrated that the reactor performance characterized by the concentration of acetylene in the product gas increased from ∼7.6 to 9.6% by optimizing the nozzle design, which indicated the critical role of the nozzle design in the coal pyrolysis process.
Assessment of cleaner process options: A case study from petroleum refining
Authors: Weston Neil , Clift Roland , Basson Lauren , Pouton Andrew , White Neil 
Published: May 2008

AbstractAssessment of process changes to reduce, recycle or avoid wastes requires attention to systems which are broader than the immediate process; that is, it is necessary to take a life cycle perspective. Definition of the system boundary for such an assessment can be problematic in itself. A real case study is presented to illustrate the problem of assessing clean technologies: possible modifications to an alkylation unit at a UK refinery. The process uses hydrogen fluoride as alkylation catalyst, and generates fluoridic wastes which are hazardous and require treatment both on‐ and off‐site. Possible changes to avoid, reduce or enable partial recycling of the waste are identified, representing different levels of change in the process and therefore requiring assessment with different system boundaries. The different system definitions lead to differences in the ways data must be compiled for quantitative environmental life cycle assessment, and in the range of stakeholders explicitly or implicitly involved in assessing and implementing the changes. The case study demonstrates some of the less familiar challenges introduced by the “pollution prevention” or “clean technology” paradigms of chemical processing.
Statistical modelling of the spouted bed coating process using positron emission particle tracking (PEPT) data
Authors: Seiler C. , Fryer P. J. , Seville J. P. K. 
Published: May 2008

AbstractCoating of particles larger than about 1 mm can be achieved in a spouted bed, a particle mobilization device in which a strong particle circulation occurs, rapidly upwards in a lean central “spout” region and downwards in a slowly moving annular settled bed. In a spouted bed coater, a spray nozzle is placed at the base of the spout, spraying upwards into a distinct coating zone. The coating formation in a spouted bed is inter alia a function of (i) the particle motion, that is, how often and where particles enter and traverse the coating zone and (ii) the extent of droplet collection by individual particles passing through the coating zone.The coating model proposed here is based on the statistical history of individual particles, whose projected area governs the collection of spray droplets in the coating zone. Positron emission particle tracking (PEPT) has been used to determine the particle trajectories, the distribution of cycle times and the size and voidage of the spout. Whilst the model is not capable of delivering absolute values of coating mass a priori, it can predict deviations from a mean, which can itself be determined from an overall mass balance.To validate the model, a spouted bed coating process was studied in which coarse PVC spheres were coated with the hot‐melt coating material polyethylene glycol (PEG) 1500. Coating mass distributions, derived from the weight data of individual particles before and after manual coating removal, compared (for the studied conditions) very well with the predictions of the model.
Evaluation of flow regimes in a semi‐cylindrical spouted bed through statistical, mutual information, spectral and Hurst's analysis
Authors: Oliveira W.P. , Souza C.R.F. , Lim C.J. , Grace J.R. 
Published: May 2008

AbstractHydrodynamic studies were conducted in a semi‐cylindrical spouted bed column of diameter 150 mm, height 1000 mm, conical base included angle of 60° and inlet orifice diameter 25 mm. Pressure transducers at several axial positions were used to obtain pressure fluctuation time series with 1.2 and 2.4 mm glass beads at U/Ums from 0.3 to 1.6, and static bed depths from 150 to 600 mm. The conditions covered several flow regimes (fixed bed, incipient spouting, stable spouting, pulsating spouting, slugging, bubble spouting and fluidization). Images of the system dynamics were also acquired through the transparent walls with a digital camera. The data were analyzed via statistical, mutual information theory, spectral and Hurst's Rescaled Range methods to assess the potential of these methods to characterize the spouting quality. The results indicate that these methods have potential for monitoring spouted bed operation.
Experimental characterization of the flow pattern in an annular fluidized bed
Authors: Collin Anne , Wirth Karl‐Ernst , Ströder Michael 
Published: May 2008

AbstractThe annular fluidized bed combines a long solids residence time and a good heat and mass transfer. To experimentally characterize the flow pattern in the system, pressure drop and capacitance probe measurements have been carried out under ambient conditions in two plants of inner diameters of 0.19 and 0.74 m. Depending on the interaction between gas velocity in the central jet and ratio of bubble to central nozzle diameter, the ratio of internal to external solids circulation can be regulated.
Fluid mechanics of liquid–solid fluidization in the centrifugal field
Authors: Margraf Jan , Werther Joachim 
Published: May 2008

AbstractThe flow pattern in the bed and in the freeboard of a liquid–solid fluidized bed operated in the centrifugal field was investigated. Centrifugal accelerations between 20 and 500 times the gravity were acting on the particles. Both the radius‐dependent centrifugal acceleration and the Coriolis force were found to strongly influence the fluid dynamics. A CFD simulation of the liquid flow in absence of particles showed high tangential velocities which were two orders of magnitude higher than the radially oriented fluidizing velocity. Measurements with a 1 m diameter rotor confirmed the calculations and revealed that also the liquid–solid fluidized bed is moving in the tangential direction although with lower speed than the pure liquid. The bed expansion under these conditions can be described by a Richardson–Zaki type correlation.
Entrained‐flow gasifier fuel blending studies at pilot scale
Authors: Cousins A. , McCalden D.J. , Hughes R.W. , Lu D.Y. , Anthony E.J. 
Published: May 2008

AbstractFor the foreseeable future, coal and petroleum‐based materials, such as petroleum Coke, residuals, and high‐sulphur fuel oil, are being adopted as the feedstocks of choice for gasification projects. Of particular interest from a Canadian perspective is Coke generated from the thermal cracking of the oil sands in Western Canada. Oil sand Coke contains high sulphur (5–6%), and also typically has a low volatile content, and lower reactivity than most coals. Experimental runs have recently been conducted on the pilot‐scale entrained‐flow gasifier at CETC‐Ottawa, blending oil sand Coke with sub‐bituminous and lignite coals, to try and enhance the gasification potential of these materials. Blending Genesee sub‐bituminous coal with the delayed oil sands Coke was found to alleviate problems encountered with slag plugging the reactor when running with Genesee coal alone. Blends of Genesee sub‐bituminous and Boundary Dam lignite coals with Coke achieved higher carbon conversions and cold gas efficiencies than runs completed with the Coke by itself. While using CO2 as the conveying gas into the gasifier was not found to significantly affect the conversion obtained, steam addition was found to have a marked effect on CO and H2 concentrations in the syngas.
New investigation in regime transition from bubbling to turbulent fluidization
Authors: Zhu Haiyan , Zhu Jesse 
Published: May 2008

AbstractThe regime transition velocity from bubbling to turbulent fluidization was investigated in a 0.267 m diameter fluidized bed with FCC particles. Different transition velocities and processes are found from the measurements of differential pressure fluctuations and local solids concentration. The measurements of differential pressure fluctuations shows a relatively quicker global regime transition, while the local regime transition obtained from the local solids concentration presents a more gradual process marked by two transition velocities. These transition velocities increase with initial static bed height. For the same initial static bed height, increasing the spacing between two pressure taps leads to lower pressure fluctuations and the appearance of two transition velocities.
An evaluation of the solid hold‐up distribution in a fluidized bed of nanoparticles using radioactive densitometry and fibre optics
Authors: Esmaeili Babak , Chaouki Jamal , Dubois Charles 
Published: May 2008

AbstractAn experimental study was conducted to assess the solid hold‐up distribution in a fluidized bed of zirconia and aluminum nanoparticles. For this purpose, two different techniques, radioactive densitometry and fibre optic measurement, were used. The results showed that while the fluidization of these nanoparticles occurs in the agglomeration state, it performs homogeneously in terms of phase concentration. This matter is important especially when a polymerization reaction should take place uniformly on the surface of nanoparticles, where the monomer is the fluidizing gas. Both techniques presented uniform solid hold‐up distribution over the cross‐section, although the fibre optic method overestimated the overall solid concentration, which was obtained based on bed expansion results. The radioactive densitometry was, however, capable of properly predicting the phase concentration within the bed according to the bed expansion observation. Finally, the effect of bulk density on the fluidization of nanoparticles was discussed by comparing the fluidization of different types of particulate materials.
Mass transfer and reaction performance of the downer and its hydrodynamic explanation
Authors: Fan Chuigang , Bi Xiaotao , Lin Weigang , Song Wenli 
Published: May 2008

AbstractCatalytic decomposition of ozone was carried out in a 15‐m high, 90‐mm inner diameter downer reactor. Radial distributions of ozone concentration at different axial elevations under different operating conditions were measured. The results were explained from the flow structure experimental data and corresponding signal analysis in time domain and frequency domain. The aggregation status of solid particles, relative movement between the gas and solids, and the dynamic behaviour of clusters were considered to have a joint influence on the mass transfer and reaction process in the downer.
Simulation of autothermal reforming in a staged‐separation membrane reactor for pure hydrogen production
Authors: Li Anwu , Lim C. Jim , Boyd Tony , Grace John R. 
Published: May 2008

AbstractSteam methane reforming with oxygen input is simulated in staged‐separation membrane reactors. The configuration retains the advantage of regular membrane reactors for achieving super‐equilibrium conversion, but reaction and membrane separation are carried out in two separate units. Equilibrium is assumed in the models given the excess of catalyst. The optimal pure hydrogen yield is obtained with 55% of the total membrane area allocated to the first of two modules. The performance of the process with pure oxygen input is only marginally better than with air. Oxygen must be added in split mode to reach autothermal operation for both reformer modules, and the oxygen input to each module depends on the process conditions. The effects of temperature, steam‐to‐carbon ratio and pressure of the reformer and the area of the membrane modules are investigated for various conditions. Compared with a traditional reformer with an ex situ membrane purifier downstream, the staged reactor is capable of much better pure hydrogen yield for the same autothermal reforming operating conditions.
Sulphation of limestones in a fluidized bed combustor: The relationship between particle attrition and microstructure
Authors: Scala Fabrizio , Montagnaro Fabio , Salatino Piero 
Published: May 2008

AbstractSulphation of two limestones in a fluidized bed combustor has been investigated. One limestone (coarse‐grained) was characterized by a significant population of relatively large pores after calcination; the other (fine‐grained) presented a finer and fairly unimodal pore size distribution. Differences in the microstructure were reflected by different thickness of the sulphate shell formed upon sulphation and ultimate calcium conversion degree. Particle attrition/fragmentation were fairly small under moderately bubbling fluidization conditions. Fragmentation upon impact was significant. The fine‐grained limestone, characterized by a thinner sulphate shell, was more susceptible to fragmentation than the other. Particle fragmentation discloses unreacted CaO enabling secondary sulphation of exhausted particles.
Reduction kinetics of a fluidizable nickel–alumina oxygen carrier for chemical‐looping combustion
Authors: Sedor Kelly E. , Hossain Mohammad M. , de Lasa Hugo I. 
Published: May 2008

AbstractThis study investigates the kinetic modelling of oxygen carrier reduction by methane in the combustion reactor of the chemical‐looping combustion process. The species being reduced and the stability of the fluidizable oxygen carrier sample over repeated reduction–oxidation cycles are established using the temperature programmed reduction and oxidation and the pulse chemisorption characterization methods. The power‐law relation, the nucleation and nuclei growth model and the shrinking‐core models are considered to interpret the experimental kinetics of the oxygen carrier reduction. The obtained results show that the nucleation and nuclei growth model best describes the experimental data providing parameters with adequate statistical fitting indicators.
Comparison of outcomes for elderly patients treated with weekly paclitaxel in combination with carboplatin versus the standard 3‐weekly paclitaxel and carboplatin for advanced nonsmall cell lung cancer
Authors: Ramalingam Suresh , Perry Michael C. , La Rocca Renato V. , Rinaldi David , Gable Preston S. , Tester William J. , Belani Chandra P. 
Published: May 2008

AbstractBACKGROUND.The purpose of this study was to compare the outcomes between elderly (aged ≥70 years) patients treated with paclitaxel on a weekly basis and with carboplatin (every 4 weeks) versus the standard 3‐weekly regimen of carboplatin and paclitaxel for first‐line therapy of advanced nonsmall cell lung cancer.METHODS.Of the 444 patients enrolled, 136 (31%) were aged ≥70 years. Seventy‐two patients were randomized to the weekly schedule (paclitaxel, 100 mg/m2 weekly for 3 of 4 weeks; carboplatin, area under the curve [AUC] = 6 mg/mL·min on Day 1 every 4 weeks), and 64 patients were randomized to the standard schedule (paclitaxel, 225 mg/m2; carboplatin, AUC = 6 mg/mL·min on Day 1 every 21 days). Patients with stable disease or objective response after 4 cycles of therapy were eligible for maintenance therapy with weekly paclitaxel (70 mg/m2, 3 of 4 weeks).RESULTS.The response rate for elderly patients was 26% on the weekly regimen and 19% on the standard schedule. The median survival duration for the weekly and the standard schedules was 37 weeks and 31 weeks, respectively. The 1‐year survival rates were similar at 31% and 33%. Grade 3 to 4 anemia was more common on the weekly schedule (16% vs 6%), whereas grade 3 neuropathy was less common (5.5% vs 9.5%). Nausea and emesis were also less frequent on the weekly schedule.CONCLUSIONS.Efficacy was similar between the weekly regimen and the standard regimen of carboplatin and paclitaxel for elderly patients with advanced NSCLC and may be advantageous based on its favorable tolerability profile. Cancer 2008. © 2008 American Cancer Society.
Quantitative assessment of glial cells in the human and guinea pig enteric nervous system with an anti‐Sox8/9/10 antibody
Authors: Hoff Sebastian , Zeller Florian , von Weyhern Claus Werner Hann , Wegner Michael , Schemann Michael , Michel Klaus , Rühl Anne 
Published: May 2008

AbstractQuantitative changes of enteric glia (EGC) have been implicated in gastrointestinal disorders. To facilitate future studies of EGC in human pathology, we aimed to characterize thoroughly glial markers in the human enteric nervous system (ENS) and to compare EGC in man and guinea pig. Whole‐mount preparations of the enteric nerve plexuses from human and guinea pig ileum and colon were labeled with antibodies against S100b, glial fibrillary acidic protein (GFAP), and p75NGFR and the transcription factors Sox8/9/10 and neuronally counterstained. Abundant immunoreactivity (IR) for S100b, GFAP, p75NGFR, and Sox8/9/10 was detected in EGC of all studied regions. Although the cytoplasmatic staining pattern of most markers did not permit glial quantification, the nuclear localization of Sox8/9/10‐IR allowed to identify and count all EGC individually. In both man and guinea pig, myenteric ganglia were larger and contained more EGC and neurons than submucous ganglia. Furthermore, there were more EGC in the human than in the guinea pig myenteric plexus (MP), glial density was consistently higher in the human ENS, and the glia index (glia:neuron ratio) ranged from 1.3 to 1.9 and from 5.9 to 7.0 in the human submucous plexus (SMP) and MP, respectively, whereas, in guinea pig, the glia index was 0.8–1.0 in the SMP and 1.7 in the MP. The glia index was the most robust quantitative descriptor within one species. This is a comprehensive set of quantitative EGC measures in man and guinea pig that provides a basis for pathological assessment of glial proliferation and/or degeneration in the diseased gut. J. Comp. Neurol. 509:356–371, 2008. © 2008 Wiley‐Liss, Inc.