bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fuel Cells, Advanced Reactors and Smart Catalysis: The Exploitation of Ceramic Ion‐Conducting Membranes
Authors: Metcalfe I.S. 
Published: August 2003

AbstractMembrane reactors are of great interest in the chemical industries because they offer the possibility of improved yields, improved selectivities and more compact plant. However, a significant barrier to their uptake is the unavailability of membrane systems having the required performance at an acceptable cost. In this paper we will explore the use of one class of membrane that has the potential to deliver high performance at reasonable cost. Ion‐conducting ceramic membranes can be used in a wide range of high temperature applications including fuel cells, advanced reactors and even smart catalytic systems.
Two‐Phase Flow with Mass Transfer in Bubble Columns
Authors: Mewes D. , Wiemann D. 
Published: August 2003

AbstractBubble columns are widely used in the chemical and biochemical industries. In these reactors a gaseous phase is dispersed into a continuous liquid phase thus the rising bubble swarm induces a circulating flow field. For the dimension of these reactors the local interfacial area and the residence time of the liquid and the gaseous phase are key parameters. In this paper an Euler‐Euler approach is used to calculate the flow field in bubble columns numerically. Therefore a transport equation for the mean bubble volume based on a population balance equation approach is coupled with the balance equations for mass and momentum. The calculations are performed for three‐dimensional, instationary flow fields in cylindrical bubble columns considering the homogeneous and the heterogeneous flow regime. For the interphase mass transfer the physical absorption of the gaseous phase into the liquid is assumed. The back mixing in the gaseous and liquid phase is calculated from the local and time dependent concentration of a tracer.
Performance of a New Mixed Down Pumping Impeller
Authors: Ascanio G. , Foucault S. , Tanguy P.A. 
Published: August 2003

AbstractA new mixed down pumping impeller was designed and characterized with both Newtonian and non‐Newtonian fluids in terms of the power consumption and mixing times. A non‐intrusive color‐discoloration technique based on a fast acid‐base reaction was used to determine mixing times and to reveal the presence of both segregated and dead zones at low speed. This new geometry gives similar mixing times to those obtained with a radial turbine but with the power requirements of an axial flow impeller. It was demonstrated that segregated regions formed below the impeller are readily destroyed by the pumping action of this new geometry, while the regions formed above the impeller are destroyed by radial discharge, so that shorter mixing times are obtained. The use of the proposed geometry appears to be a good alternative for mixing applications requiring a good dispersion combined with low power consumption.
Nonstationary Simulation Model of Absorber with Falling Film of Suspension
Authors: Gerbeč M. , Stergaršek A. , Kocjančič R. 
Published: August 2003

AbstractA nonstationary model of SO2 absorption from a gas phase to a countercurrent falling film of absorbing slurry was developed. Laminar, wavy and turbulent film structures were considered based on published information. Resistances to the mass transfer on the gas and the liquid sides of the interphase were considered, together with chemical reactions in the liquid phase. Relevant chemical equilibria in the liquid phase were modeled. Original experimental data on the neutralization reagent dissolution rate presented as a polydispersed two‐phase system of solids and on the rate of dissolved sulfite oxidation were used. The model was verified with experimental data from a laboratory‐scale falling‐film absorber using a single vertical tube under various geometrical and operating conditions, and a very good agreement was found with the experiment. Parametric sensitivity analysis showed the critical parts of the model.
Theoretical Investigation of a Pd‐membrane Reactor for Methanol Synthesis
Authors: Rahimpour M.R. , Ghader S. 
Published: August 2003

AbstractA numerical study is performed in order to evaluate the performance and optimal operating conditions of a palladium membrane reactor for methanol synthesis. A novel reactor configuration with a Pd wall, which is perm‐selective to hydrogen, has been proposed. In this configuration the reactants are added to the tube side while pure hydrogen is added to the shell side, as a result, the hydrogen diffuses across the membrane from the shell side to the tube side. In this membrane reactor, hydrogen penetrates to the reaction side in order to maintain a suitable hydrogen level in the whole length of the reactor and shift the equilibrium reaction. The effects of different parameters on the methanol output mole fraction were investigated in the co‐current mode. These parameters were membrane thickness, reaction side flow rate, reaction side pressure, shell side pressure and H2/CO2 ratio in the feed.
Monitoring Crystallization Kinetics of Azelaic Acid by in situ FTIR Spectroscopy in Three‐Phase Systems
Authors: Nattkemper A. , Schleiden T. , Migliavacca J.M. , Melin T. 
Published: August 2003

AbstractThe evolution of solid particles during crystallization frequently makes it impossible to measure concentration profiles by conventional sampling. Concentration profiles of the liquid phase can still be measured by coupling an ATR deep‐immersion probe with a FTIR spectrometer. Using this system concentration profiles of azelaic acid initially dissolved in acetone could be obtained. Cooling is accomplished by directly injecting liquid carbon dioxide into the reaction mixture which causes the mixture to be a three‐phase system. Although the system is highly turbulent, CO2 gas bubbles and evolving azelaic acid particles were not observed to influence the IR signal. Four different cooling rates of 4.2, 11.7, 18.5, and 26.1 °C/min were investigated. Concentration data points are obtained every five seconds giving a total of up to one hundred data points depending on the experimental settings. The FTIR absorption spectra are converted to volume‐based concentration profiles by an interpolation type algorithm. Further conversion to mass‐based concentration profiles made it possible to track the exact starting time of the crystallization process. It also eliminates the effect of decreasing temperature on the concentration profiles. By a comparison of all four experiments the detection of sub‐cooling with increasing cooling rates is possible.
Arsen‐Metabolismus im Menschen: Kopplung von Festphasenmikroextraktion und GC‐MS
Authors: Sur Robin , Hajimiragha Hossein , Begerow Jutta , Dunemann Lothar 
Published: August 2003

AbstractEine neuartige Kopplungstechnik für die Bestimmung von Hintergrundkonzentrationen an Trimethylarsinoxid (TMAO) und anderen Metaboliten des Arsens im menschlichen Urin wurde entwickelt. Die Ergebnisse liefern neue Einblicke in den Arsen‐Metabolismus im menschlichen Organismus bei umweltbedingter Arsen‐Exposition.
Proteine der Photosynthese: Aus Licht wird Leben
Authors: Harrer Roswitha 
Published: August 2003

AbstractPhotosynthesis is based on a fascinating interplay between proteins, pigments and membranes. The cleavage of water molecules takes place in photosystem II which is excited by light. Recent structure elucidation of photosystem II helped in understanding the electron transfer reaction but the water splitting mechanism is still not solved. The light energy is stored in ATP, which is synthesized by the ATP Synthase, a molecular motor. Its membrane part, the c‐ring, mediates the transfer of protons. Structure and function of ATP Synthase are currently under intensive investigation.
Lithium und seine Verbindungen ‐ Industrielle, medizinische und wissenschaftliche Bedeutung
Authors: Deberitz Jürgen , Boche Gernot 
Published: August 2003

AbstractDer Aufsatz bietet eine kurze Zusammenfassung über die industrielle, medizinische und wissenschaftliche Bedeutung von Lithium und seinen Verbindungen. So ist Lithiumcarbonat von großer Wichtigkeit bei der Glas‐, Email‐ und Keramikherstellung; verschiedene anorganische Lithiumverbindungen dienen als Zementverfestiger, und Lithium‐Fette, d. h. Schmieröle mit Lithiumsalzen von langkettigen aliphatischen Carbonsäuren, sind aus der modernen Technik genauso wenig wegzudenken, wie LiOH als CO2‐Fänger, LiCl (LiF) in der Aluminiumverarbeitung und gewinnung oder LiBr (LiCl) in Kühlanlagen. Bei der Behandlung manisch‐depressiver Erkrankungen haben sich Lithium‐Salze einen festen Platz gesichert. Metallisches Lithium findet zunehmend Anwendung in Batterien. Dass es ohne 6 Lithium keine Wasserstoffbombe gäbe, ist auch nicht allgemein bekannt. Ein Abfallprodukt: der billige Zugang zu 6 Lithium und die daraus entwickelte 6 Li‐NMR‐Spektroskopie. Schließlich einige Hinweise auf Lithium‐organische Verbindungen und ihre große Bedeutung in der modernen (organischen) Synthese, sowohl in Labors als auch in der Technik (z.B. anionische Polymerisation). Ein besonders wichtiges Kapitel stellt die stereoselektive Synthese mit Hilfe von Lithium‐organischen Verbindungen dar.
Woher kommt das Wasser der Erde? ‐ Urgaswolke oder Meteoriten
Authors: Müller Jörn , Lesch Harald 
Published: August 2003

AbstractWasser ist eines der häufigsten Moleküle im Universum. Nachdem der Wasserstoff bereits kurz nach dem Urknall entstand, wurde der für Wasser nötige Sauerstoff erst viel später in den Sternen fusioniert. In den staubbeladenen Wolken des interstellaren Mediums verbanden und verbinden sich noch heute diese Elemente zu Wasser. Wie aber kam das Wasser auf die Erde? Entweder hat es die Erde bei ihrer Entstehung aus einer Gasscheibe mitbekommen oder es wurde durch Kometen auf die Erde gebracht. Ob beide Prozesse oder nur einer Anteil am Wasser der Erde haben, ist gegenwärtig noch nicht entschieden. Menge an Staub ist der ideale Untergrund für die Bildung von Molekülen und vor allem auch vom Wassermolekül.
Die Reaktivdestillation: Moderne Trenn‐ und Reaktionstechniken
Authors: Sundmacher Kai , Ivanova Mariyana 
Published: August 2003

AbstractDie Reaktivdestillation beruht auf der Integration der chemischen Umsetzung eines Eduktgemisches und der stofflichen Aufarbeitung des Produktgemisches in einem einzigen Apparat, der in der Regel als Gegenstromkolonne ausgeführt ist. Die Motive für den Einsatz dieser Technologie sind vielfältig. Bei der Durchführung von Gleichgewichtsreaktionen können häufig deutlich höhere Umsätze als in konventionellen einphasigen Reaktoren erreicht werden. Unerwünschte Folgereaktionen können durch eine verbesserte Konzentrationsführung der Reaktivdestillation unterdrückt werden, so dass die Selektivität bezüglich der Zielprodukte erhöht wird.Bei stark exothermen Umsetzungen ist der Temperaturanstieg in einer reaktiven Destillationskolonne besser kontrollierbar. Darüber hinaus können auch solche Mischungen, die durch konventionelle Destillation nicht oder nur sehr schwer in ihre Einzelkomponenten trennbar sind, aufgearbeitet werden. Diese Vorteile führen zur signifikanten Reduzierung von Investitions‐und Betriebskosten. Infolge der synergetischen Wechselwirkungen von chemischer Reaktion und Destillation in einem Apparat zeigen Prozesse der Reaktivdestillation häufig komplexes Betriebsverhalten. Daher ist die Auslegung dieser integrierten Prozesse deutlich anspruchsvoller als die Auslegung konventioneller Reaktor‐Separator‐Sequenzen.
Bakterien für den Denkmalschutz
Authors: Jacoby Petra 
Published: August 2003

AbstractSaurer Regen und andere Folgen der wachsenden Umweltverschmutzung schädigen immer stärker wertvolle Kunstwerke aus Kalkstein. Eine neue Methode, bei der Bakterien verlorengegangenes Material wieder auffüllen, könnte Denkmäler in Zukunft möglicherweise vor dem schleichenden Verfall retten.
Polymere Linse mit Wirkstoffdepot
Authors: Feil Sylvia 
Published: August 2003

AbstractDer Graue Star lässt die Linsen im Auge eintrüben. Der Katarakt kann zu einer Erblindung führen, die nur durch eine Operation zu behandeln ist. Dabei wird die trübe Linse entfernt und eine künstliche in den Kapselsack, also intraokular, implantiert. Bei einem ausgeprägten Grauen Star lässt sich die Linse nur schwer vollständig entfernen. Einzelne Epithelzellen verbleiben und können wieder vom Rand des Linsensackes zur Mitte der implantierten polymeren Linse hin wachsen. Diese Proliferation kann zu einem Nachstar führen, der behandelt werden muss. Dabei werden derzeit die aufgewachsenen Zellen mit einem Laser mechanisch entfernt. Eine nicht‐invasive Methode zur Nachbehandlung des Grauen Stars entwickeln nun die Arbeitsgruppen von Andreas Greiner und Norbert Hampp an der Universität Marburg [1‐3].
Reaktionssteuerung am Einzelmolekül
Authors: Groß Michael 
Published: August 2003

AbstractIm Modellbaukasten geht es so einfach. Man nimmt ein Molekül in die Hand, stöpselt ein paar Bindungen um, und schon hat man es in ein anderes Molekül umgewandelt. Was wäre, wenn man echte Moleküle ebenso leicht gezielt herausgreifen und zur Stoffumwandlung zwingen könnte? Erste zaghafte Schritte in dieser Richtung sind bereits möglich.
CAS bringt Übersicht in die publizierte Chemie
Authors: Hübner Karl 
Published: August 2003

AbstractSeit 1907 gibt es die Chemical Abstracts. Heute bietet der Chemical Abstracts Service die vermutlich umfangreichsten chemischen Datenbanken. Ganz nebenbei ist mit dem CAS Registry auch ein Register entstanden, das jederzeit die bekannte stoffliche Vielfalt widerspiegelt. Im Juni 2003 wurde die 50.000.000ste Substanz registriert. Der Zuwachs ist rasant. Noch zum Jahrtausendwechsel kannte die Menschheit nicht einmal halb so viele Stoffe.
Höhepunkte aus Liebigs Experimentalvorlesung
Authors: Schwedt Georg 
Published: August 2003

AbstractAm 12. Mai 1803 wurde Liebig in Darmstadt geboren. Aus Anlass seines 200. Geburtstages wurden Experimente aus seiner in Gießen entwickelten Experimentalvorlesung ausgewählt. In diesem Beitrag wird aus Liebigs Vorlesungsbuch das Metall Kupfer anhand heute klassischer Reaktionen vorgestellt. Als Ergänzung werden auch Zitate aus Kekul?s Mitschrift verwendet.
Kosmetik ‐ Chemie mit Charme?
Authors: Hildebrandt Henry 
Published: August 2003

AbstractChemie hat in der Öffentlichkeit Imageprobleme ‐ darüber herrscht wohl Einigkeit. Genauso einig sind sich die mit Chemie befassten Personen, dass dieser Zustand unhaltbar ist. Weniger Einigkeit besteht darüber, was die Ursachen sind sowie darüber, wie Öffentlichkeitsarbeit für Chemie betrieben werden kann. Vielleicht kann das Internet hier Hinweise geben.
Psychological well being and quality of life in ovarian cancer survivors
Authors: Ferrell Betty , Smith Stephany L. , Cullinane Carey A. , Melancon Cindy 
Published: August 2003

AbstractBACKGROUNDThis report offers a unique analysis of the psychological distress associated with ovarian cancer in a review of natural correspondence between ovarian cancer survivors and an ovarian cancer newsletter.METHODSA review of 21,806 letters, cards, and e‐mails reflecting correspondence from January 1994 to December 2000 between ovarian cancer survivors and the founding editor of Conversations!: The International Newsletter for those Fighting Ovarian Cancer was performed using ethnographic qualitative research methods. Statements related to the impact of disease were bracketed and coded within physical, psychological, social, and spiritual domains according to the City of Hope Quality of Life Ovarian Cancer instrument. Statements that reflected psychological well being were then evaluated with respect to the disease trajectory (i.e., diagnosis, treatment, remission, recurrence, and advanced disease/end of life).RESULTSA total of 1282 communications were identified that pertained to psychological well being. Findings based on major themes derived from the analysis included descriptions of stressors associated with disease status. Significant stressors were identified within all phases of diagnosis, treatment, remission, and recurrence. Women described both positive and negative effects of disease and frequently demonstrated resourcefulness and perseverance by sharing coping mechanisms and survival strategies.CONCLUSIONSThe natural correspondence from women with ovarian cancer provided a rare opportunity to capture the psychological concerns of women throughout all stages of the cancer trajectory. Health care professionals' awareness of the common psychological stressors throughout the ovarian cancer trajectory may allow them to identify more readily the needs for support, leading to improvement in overall quality of life. Cancer 2003;98:1061–71. © 2003 American Cancer Society.DOI 10.1002/cncr.11291
A Phase II study of intravenous exatecan mesylate (DX‐8951f) administered daily for 5 days every 3 weeks to patients with metastatic breast carcinoma
Authors: Esteva Francisco J. , Rivera Edgardo , Cristofanilli Massimo , Valero Vicente , Royce Melanie , Duggal Anil , Colucci Philippe , DeJager Robert , Hortobagyi Gabriel N. 
Published: August 2003

AbstractBACKGROUNDThe objective of the current study was to determine the antitumor activity, safety, and pharmacokinetic (PK) profile of exatecan mesylate in patients with anthracycline‐resistant and taxane‐resistant, metastatic breast carcinoma.METHODSAll patients had clinical evidence of metastatic breast carcinoma; disease resistance or progression after chemotherapy that included anthracyclines and taxanes; no prior chemotherapy with camptothecin derivatives; and bidimensionally measurable disease. The starting dose of exatecan mesylate was either 0.5 mg/m2 per day or 0.3 mg/m2 per day, depending on prior chemotherapy exposure. PK blood samples were collected from each patient during the first course of therapy.RESULTSThirty‐nine patients received a total of 172 courses of therapy (median, 4 courses; range, 1–16 courses). Three patients (7.7%) had a partial response, and 20 patients (51.3%) had either a minor response or stable disease. Approximately 20% of patients had stable disease for 6 months or longer. The median time to disease progression was 3 months, and the median survival was 14 months. The most frequent severe adverse event was neutropenia. The most frequent severe (Grade 3–4) nonhematologic toxicities were fatigue, nausea, headache, myalgia, constipation, emesis, and paresthesias in 28%, 10%, 10%, 8%, 8%, 5%, and 5% of patients, respectively. Exatecan mesylate displayed linear PK characteristics at the doses administered. The average plasma clearance, total volume of distribution, and terminal elimination half‐life were approximately 1.4 L per hour per m2, 12 L/m2, and 8 hours, respectively.CONCLUSIONSExatecan mesylate had moderate activity in patients with anthracycline‐refractory and taxane‐refractory, metastatic breast carcinoma. The toxicity profile of exatecan mesylate was acceptable, and it appeared to have linear PK characteristics on the basis of multiple dose administration. Cancer 2003;98:900–7. © 2003 American Cancer Society.DOI 10.1002/cncr.11557
Histologic grade, stage, and survival in breast carcinoma
Authors: Earl Henson Donald , Chu Kenneth C. , Levine Paul H. 
Published: August 2003

AbstractBACKGROUNDAfrican American women have lower breast carcinoma survival rates than do Caucasian women. African American women often present with advanced‐stage disease and more aggressive tumors as shown by histologic and laboratory‐based prognostic factors. Aggressive tumor behavior may be responsible, at least in part, for the advanced stage and reduced survival rates.METHODSThe authors investigated the correlation between survival and histologic grade, stage of disease, and tumor size for both African American and Caucasian women who were younger than age 50 years and age 50 years and older. The authors also investigated the distribution of grade within each stage group and the distribution of grade by tumor size. African American and Caucasian women were matched by stage, tumor size, and histologic grade. Survival was represented by 6‐year breast carcinoma–specific survival rates.RESULTSCompared with Caucasian women, African American women, regardless of age, had proportionally more Grade III tumors and fewer Grade I and II tumors for all stages combined and for each individual stage group. Similarly, matched for tumor size, African American women had more Grade III tumors and fewer Grade I and II tumors compared with Caucasian women, except for tumors smaller than 1.0 cm. For nearly all combinations of stage and grade regardless of age, the 6‐year breast carcinoma–specific survival rate was lower for African American women than for Caucasian women, although it did not always reach statistical significance.CONCLUSIONSCompared with Caucasian women, African American women, regardless of age, presented with proportionally more aggressive tumors for each stage of disease and for each tumor size above 1.0 cm as revealed by the histologic grade. Higher histologic grade may be a significant contributing factor to survival disadvantage for African American women. Cancer 2003;98:908–17. Published 2003 by the American Cancer Society.DOI 10.1002/cncr.11558
Sentinel lymph nodes with technetium‐99m colloidal rhenium sulfide in patients with esophageal carcinoma
Authors: Kato Hiroyuki , Miyazaki Tatsuya , Nakajima Masanobu , Takita Junko , Sohda Makoto , Fukai Yasuyuki , Masuda Norihiro , Fukuchi Minoru , Manda Ryokuhei , Ojima Hitoshi , Tsukada Katsuhiko , Asao Takayuki , Kuwano Hiroyuki , Oriuchi Noboru , Endo Keigo 
Published: August 2003

AbstractBACKGROUNDThe authors assessed the detection of sentinel lymph nodes in patients with esophageal squamous cell carcinoma (SCC) using technetium‐99m colloidal rhenium sulfide. They studied whether an analysis of sentinel lymph nodes using cytokeratin (CK) immunohistochemistry increased the accuracy of staging.METHODSThe authors observed 25 patients with thoracic esophageal carcinomas who underwent radical esophagectomy. The day before surgery, technetium‐99m colloidal rhenium sulfide was injected into the submucosa at four sites around the primary tumor. Lymphoscintigraphy was performed. Esophagectomy and regional lymph node dissection were performed 17 hours after the technetium‐99m injection. After surgery, the resected lymph nodes were evaluated by CK staining.RESULTSLymphoscintigraphy detected sentinel lymph nodes in 92% of the patients (23 of 25 patients). The accuracy of sentinel lymph node was 91.3% (21 of 23 patients), the sensitivity was 86.7% (13 of 15 patients), and the false‐negative rate was 8.7% (2 of 23 patients). A comparison of the number of sentinel lymph nodes and clinicopathologic factors showed that there was a significant association between the number of sentinel lymph nodes and lymph node status (P < 0.01), pathologic stage (P < 0.05), and the number of metastatic lymph nodes (P < 0.05). Occult metastasis was detected by CK staining in 14 (56%) of the 25 patients and in 23 (1.7%) of 1406 lymph nodes. Because the 2 false‐negative (sentinel lymph node–negative and nonsentinel lymph node–positive) patients who had occult metastases in the sentinel lymph nodes, the accuracy of sentinel lymph node evaluation using CK staining was 100% (23 of 23).CONCLUSIONSLymphatic mapping with technetium‐99m colloidal rhenium sulfide was used to identify the lymphatic basin and was feasible in patients with esophageal SCC. An analysis of sentinel lymph nodes using CK immunohistochemistry increased the accuracy of sentinel lymph node. Cancer 2003;98:932–9. © 2003 American Cancer Society.DOI 10.1002/cncr.11559