bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prediction of Axial Mixing for a Structured Packed Column Using a Two‐equation Model
Authors: Zhang W. W. , Liu C. J. , Yuan X. G. , Yu G. C. 
Published: January 2008

AbstractA theoretical model based on the recently developed $ \overline {c^2}-\varepsilon _{\rm c} $ two‐equation method is proposed to predict the axial mixing behavior in a structured packed column. By solving the proposed model, the process of tracer injection experiments for determining the axial back‐mixing coefficient of structured packing can be simulated. Consequently, the axial Bodenstein number and dispersion coefficient under liquid single‐phase or gas‐liquid two‐phase flow conditions can be calculated. The validation of the proposed method is tested by simulating the two‐phase fluid flow behavior in Flexipac 2 structured packing. The simulated results are compared with the experimental data and satisfactory agreement is found between the simulation and the experiments.
Design of a Flexible Pilot Plant Reactor for the Steam Cracking Process
Authors: Karimzadeh R. , Ghashghaee M. 
Published: January 2008

AbstractA design technique for a pilot plant reactor of single diameter is presented to scale up or down steam cracking coils of different configurations like mono‐tubular, classical, and reversed splits. Using dimensional analysis, two criteria are selected in establishing partial similarity between different scales, the mean residence time, and the axial pressure profile in the reactor, in addition to preserving the flow pattern within the turbulent region. The sensitivity and accuracy of the proposed method is compared to another conceivable alternative that focuses on the lateral gradients. The pilot reactor coil is adapted for any large‐scale reactor by the adjustment of feed flow rate and the effective length exposed to the firebox heat flux. Simulation results for naphtha cracking in a commercial split coil and also the equivalent pilot plant reactors are used for verification and validation of this method.
Production and Characteristics of an Enantioselective Lipase from Burkholderia sp. GXU56
Authors: Wei H.‐N. , Shi L.‐L. , Wu B. 
Published: January 2008

AbstractThe lipase production of Burkholderia sp. GXU56 was influenced by carbon and nitrogen sources, inorganic salts, initial pH of the medium and cultivation temperature. The maximum lipase production was 580.52 U/mL and reached 5 times the level of the basic medium in the optimum medium at pH 8.0, 32 °C, 200 rpm and 40–48 h. The lipase was purified 53.6 fold to homogeneity and the molecular weight was 35 KDa on SDS‐PAGE. The optimum pH and temperature of the lipase were 8.0 and 40 °C, respectively, and it was stable in the range of pH 7–8.5 and at temperatures below 45 °C. The lipase activity was strongly inhibited by Zn2+, Cu2+, Co2+, Fe2+, Fe3+ ions and SDS, while it was stimulated by Li+ and Ca2+ ions and in presence of 0.1 % CTAB, 0.1 % Triton X‐100 and 10 % DMSO. Km and Vmax of the lipase were calculated to be 0.038 mmol/L, and 0.029 mmol/L min–1, respectively, with PNPB as the substrate. The GXU56 lipase showed enantioselective hydrolysis of (R,S)‐methyl mandelate to (R)‐mandelic acid, which is an important intermediate in the pharmaceutical industry.
Spontaneous Organization of Uniform CeO2 Nanoflowers by 3D Oriented Attachment in Hot Surfactant Solutions Monitored with an In Situ Electrical Conductance Technique
Authors: Zhou Huan‐Ping , Zhang Ya‐Wen , Mai Hao‐Xin , Sun Xiao , Liu Qiang , Song Wei‐Guo , Yan Chun‐Hua 
Published: February 2008

AbstractUniform CeO2 nanoflowers were synthesized by rapid thermolysis of (NH4)2Ce(NO3)6 in oleic acid (OA)/oleylamine (OM), by a unique 3D oriented‐attachment mechanism. CeO2 nanoflowers with controlled shape (cubic, four‐petaled, and starlike) and tunable size (10–40 nm) were obtained by adjusting the reaction conditions including solvent composition, precursor concentration, reaction temperature, and reaction time. The nanoflower growth mechanism was investigated by in situ electrical conductance measurements, transmission electron microscopy, and UV/Vis spectroscopy. The CeO2 nanoflowers are likely formed in two major steps, that is, initial formation of ceria cluster particles capped with various ligands (e.g., OA, OM, and NO3−) via hydrolysis of (NH4)2Ce(NO3)6 at temperatures in the range 140–220 °C, and subsequent spontaneous organization of the primary particles into nanoflowers by 3D oriented attachment, due to a rapid decrease in surface ligand coverage caused by sudden decomposition of the precursor at temperatures above 220 °C in a strong redox reaction. After calcination at 400 °C for 4 h the 33.8 nm CeO2 nanoflowers have a specific surface area as large as 156 m2 g−1 with high porosity, and they are highly active for conversion of CO to CO2 in the low temperature range of 200–400 °C. The present approach has also been extended to the preparation of other transition metal oxide (CoO, NiO, and CuOx) nanoflowers.
Untersuchung der Flüssigkeitsabscheidung verschiedener Dampfverteilsysteme in Trennkolonnen
Authors: Wehrli M. , Schaeffer P. , Kooijman H. A. 
Published: January 2008

AbstractFür den Betrieb der Rohöl‐Vakuumkolonne ist eine gute Abscheidung der im Toprückstand eingetragenen Flüssigkeit vorteilhaft. Zu diesem Zweck wird häufig ein Dampfverteiler in die Eintrittssektion der Trennkolonne eingebaut. Die vorliegende Arbeit untersucht die Flüssigkeitsabscheidung verschiedener Dampfverteiler mit Luft und Wasser. Im Vergleich zum Direkteintritt erreichen die drei getesteten Systeme eine deutlich höhere Abscheideleistung. Ergänzend zu den Experimenten ermöglicht die numerische Strömungssimulation eine Bewertung der Geschwindigkeitsverteilung über dem Dampfeintritt. Ein Vergleich der so gewonnen Information mit den experimentellen Daten mitgerissenen Wassers legt den Schluss nahe, dass ein gleichförmiges Geschwindigkeitsfeld als Entscheidungshilfe bei der Auswahl des Dampfverteilers hinsichtlich Flüssigkeitsabscheidung nicht genügt. – Der theoretische Teil dieses Beitrags widmet sich Ähnlichkeitskriterien, die bei der Übertragung der Luft/Wasser‐Experimente auf die Bedingungen in einer Rohöl‐Vakuumkolonne zu berücksichtigen sind.
Synthese von Downstreamprozessen
Authors: Bauer K. , Schembecker G. 
Published: January 2008

AbstractFür die Entwicklung neuer biotechnologischer Prozesse sowie die Maßstabsvergrößerung bestehender ist es wichtig, dass systematische Prozesssynthesemethoden ausgearbeitet werden. Dabei ist es sinnvoll schon vorhandene Methoden aus der chemischen Prozessentwicklung (hier die Dekompositionsmethode) zu übertragen und an die Besonderheiten biotechnologischer Verfahren anzupassen. Außerdem werden zur Auswahl einer geeigneten Trennsequenz Heuristiken abgeleitet. Wichtig ist es, den Fokus nicht ausschließlich auf die Optimierung des Fermentationsschrittes zu legen, sondern auf die Entwicklung eines optimalen Gesamtprozesses.
Neue Auswertungsalgorithmen und optimierte Anregung für die Temperaturoszillationskalorimetrie
Authors: Mauntz W. , Engell S. , Krämer S. , Diehl M. 
Published: January 2008

AbstractExotherme Reaktionen, wie z. B. Polymerisationsreaktionen in Rührkesselreaktoren, werden vielfach mit Hilfe der Kalorimetrie untersucht und überwacht. Dazu wird üblicherweise die Reaktorwärmebilanz ausgewertet. Für den Fall eines unbekannten oder z. B. auf Grund von Viskositätsänderungen veränderlichen Wärmedurchgangskoeffizienten k kann zusätzlich zu dessen Schätzung die Reaktormantelwärmebilanz herangezogen werden. Bei großen Kühlmitteldurchflüssen durch den Mantel versagt diese Methode allerdings wegen ihrer Rauschempfindlichkeit. Als Alternative wurde in der Literatur die Oszillationskalorimetrie vorgeschlagen, bei der leichte Schwingungen der Reaktortemperatur erzeugt werden. Die in der Literatur vorgestellten Methoden sind allerdings mit dem Nachteil behaftet, dass sie nur im eingeschwungenen Zustand des Systems angewandt werden können. In dieser Arbeit werden vier alternative Auswertungsalgorithmen präsentiert sowie die Frage, welches Anregungssignal eine optimale Schätzung von k ermöglicht.
Verhalten verschiedener Membranmaterialien für die Aufbereitung organischer Produktströme aus Reaktivrektifikationskolonnen
Authors: Brinkmann T. , Pingel H. , Wolff T. 
Published: January 2008

AbstractIn dieser Arbeit werden verschiedene kommerziell erhältliche sowie sich in der Entwicklung befindliche Membranmaterialien für die Trennung von Methanol/Methylacetatgemischen charakterisiert, die z. B. als Kopfprodukt in Reaktivrektifikationskolonnen anfallen. Das Permeationsverhalten der Membranmaterialien wurde sowohl in der Pervaporation als auch in der Dampfpermeation untersucht. Ferner dienten die Ergebnisse der Dampfpermeationsmessungen für eine Simulation des Trennverfahrens.
Modellierung des flüssigkeitsseitigen Stoffüberganges in Kolonnen mit klassischen und gitterförmigen Füllkörpern
Authors: Maćkowiak J. 
Published: January 2008

AbstractIm vorliegenden Beitrag wird eine neue allgemeingültige Beziehung zur Bestimmung des flüssigkeitsseitigen volumetrischen Stoffübergangskoeffizienten βL ae, der volumenbezogenen Phasengrenzfläche ae und des Stoffübergangskoeffizienten βL für sämtliche vollflächige und Gitterfüllkörper mit der Nenngröße von 12 bis 90 mm für Gas/Flüssig‐Systeme vorgestellt. Diese neue Beziehung wurde unter der Annahme hergeleitet, dass in der Füllkörperschüttung die Flüssigkeit vorwiegend in Form von Tropfen herabfließt und der Stoffübergang instationär abläuft und auf dem Kanalmodell mit teils offener Umwandung aufbaut. Sie beinhaltet nur eine einzige für sämtliche untersuchte Füllkörperformen geltende Modellkonstante, und gilt sowohl unterhalb der Staugrenze FV <$>\leq<$> 0,65 FV,Fl, als auch bis zur Flutgrenze. Aus dem für disperse Systeme geltenden Ansatz wurde die Beziehung für die effektive volumenbezogene Phasengrenzfläche ae abgeleitet und in dimensionsloser Darstellung präsentiert. Die experimentell ermittelte Stoffaustauschfläche in Füllkörperschüttungen ae unterschiedlicher Form stimmt mit der Rechnung nach dem neuen Ansatz zufriedenstellend überein. Somit ist eine Trennung des Produktes βL ae in βL und ae möglich.
Laser‐induced autofluorescence spectral ratio reference standard for early discrimination of oral cancer
Authors: Mallia Rupananda J. , Thomas Shiny Sara , Mathews Anitha , Kumar R Rejnish , Sebastian Paul , Madhavan Jayaprakash , Subhash Narayanan 
Published: February 2008

AbstractBACKGROUNDLaser‐induced autofluorescence (LIAF) is an emerging noninvasive technique in the biomedical field, especially for cancer detection. The goal of the study was to develop a spectral ratio reference standard (SRRS) to discriminate different grades of oral cancer.METHODSLIAF emission spectra from oral mucosa were recorded in the 420–720 nm spectral range on a miniature fiberoptic spectrometer from 14 anatomical sites of 35 healthy volunteers and 91 sites of 44 patients, with excitation at 404 nm from a diode laser.RESULTSHistopathologic analysis of biopsy samples showed that oral mucosa of adjoining malignant sites in patients are not usually normal, but showed various degrees of epithelial dysplasia and hyperplasia. Therefore, instead of using LIAF data from apparently normal lesions of patients as control, spectral data values of the oral mucosa of healthy volunteers were used as control. The autofluorescence emission at 500 nm is characteristic of oral mucosa, whereas in malignant lesions a new peak is seen at 685 nm in addition to the previously reported peaks at 635 and 705 nm. Three spectral ratio reference standard (SRRS) scatterplots were created to differentiate the normal mucosa from hyperplasia, hyperplasia from dysplasia, and dysplasia from squamous cell carcinoma (SCC) using the mean fluorescence intensity ratios (F500/F635, F500/705 and F500/F685) measured from 40 sites in 20 patients and 11 sites in 35 healthy volunteers. During blind tests at 21 sites in 17 patients all 3 SRRS plots showed 100% sensitivity and specificity to discriminate hyperplasia from dysplastic and normal tissues, whereas only the F500/F685 SRRS showed the same sensitivity and specificity to differentiate dysplasia from SCC.CONCLUSIONSAn SRRS criteria based on scatterplots of autofluorescence spectral intensity ratios is described to discriminate oral mucosal variations and screen early stages of tissue progression toward malignancy. Cancer 2008. © 2008 American Cancer Society.
Myelomatous meningitis
Authors: Chamberlain Marc C. , Glantz Michael 
Published: February 2008

AbstractBACKGROUNDThe most frequent nervous system complications of multiple myeloma are peripheral neuropathy and epidural spinal cord compression. Myelomatous meningitis (MM) has been considered rare. The current study was performed to characterize the clinical presentation, treatment, and outcome of MM.METHODSThe study was a case series of 14 patients with cerebrospinal fluid (CSF)‐positive MM who were treated at a tertiary care university medical center.RESULTSFourteen patients with advanced multiple myeloma were treated with involved‐field radiotherapy (to the brain in 5 patients and the spine in 6 patients) and intra‐CSF chemotherapy (ventricular in 10 patients and lumbar in 4 patients). The best response to treatment included 6 partial responses and 8 patients with progressive disease. The median duration of response was 2.5 months (range, 0–6 months). Cause of death was progressive neurologic disease in 6 patients, combined systemic and neurologic disease in 6 patients, and systemic disease progression in 2 patients.CONCLUSIONSMM is rare and morbid entity (6‐month neurologic disease progression‐free survival rate of 7%), and appears to be no more responsive to treatment than solid tumor carcinomatous meningitis. Cancer 2008. © 2008 American Cancer Society.
Identification of survival‐related genes of the phosphatidylinositol 3′‐kinase signaling pathway in glioblastoma multiforme
Authors: Ruano Yolanda , Mollejo Manuela , Camacho Francisca I. , de Lope Angel Rodríguez , Fiaño Concepción , Ribalta Teresa , Martínez Pedro , Hernández‐Moneo Jose‐Luis , Meléndez Bárbara 
Published: February 2008

AbstractBACKGROUNDKnowledge of the molecular mechanisms involved in the biology of glioblastoma multiforme (GBM) is essential for the identification of candidate prognostic markers, new putative therapeutic targets, and early detection strategies predictive of survival.METHODSThe authors performed expression‐profiling analyses in a series of primary GBMs by using complementary DNA microarrays. Validation of putative targets was performed in large series of GBMs by immunohistochemistry on tissue microarrays, real‐time quantitative reverse transcription‐polymerase chain reaction analysis, and Western blot analysis.RESULTSThe expression signature consisted of 159 up‐regulated genes and 186 down‐regulated genes. Most of these genes were involved in cell adhesion, signal transduction, cell cycle, apoptosis, and angiogenesis. Among the genes from the molecular signature, annexin 1 (ANXA1) and ubiquitin‐specific protease 7 (USP7) were evaluated in wider series of GBMs. ANXA1 analysis carried out in different types of gliomas revealed exclusive overexpression in astrocytomas. Furthermore, survival analysis by using functional clusters of genes related with cancer and glioma biology revealed 7 genes involved in the PI3K‐signaling pathway that presented a significant association with clinical outcome. Among these genes, positive expression of BCL2‐associated X protein (BAX) was associated significantly with better survival in a larger series of tumors. In addition, activation of the PI3K/Akt pathway was demonstrated in this set of GBMs.CONCLUSIONSThe authors concluded that there is a significant role for PI3K pathway survival‐related genes in patients with GBM, and putative prognostic markers associated with glioma tumorigenesis were identified. The detailed study of these candidate genes and the molecular pathways regulating PI3K activation reveal that they are promising targets for the clinical management of patients with glioma. Cancer 2008. © 2008 American Cancer Society.
A priori estimates for fluid interface problems
Authors: Shatah Jalal , Zeng Chongchun 
Published: February 2008

AbstractWe consider the regularity of an interface between two incompressible and inviscid fluid flows in the presence of surface tension. We obtain local‐in‐time estimates on the interface in H(3/2)k + 1 and the velocity fields in H(3/2)k. These estimates are obtained using geometric considerations which show that the Kelvin‐Helmholtz instabilities are a consequence of a curvature calculation. © 2007 Wiley Periodicals, Inc.
Preparation and Oxygenation of Cobalt N‐Confused Porphyrin Nitrosyl Complexes
Authors: Hung Chen‐Hsiung , Peng Chih‐Hsiung , Shen Yi‐Ling , Wang Sian‐Ling , Chuang Chuan‐Hung , Lee Hon Man 
Published: January 2008

AbstractThe nitrosylation of Co(HCTPP) (1) in CH2Cl2 afforded [Co(CTPPC2H2Cl)(NO)] (2) with a chlorovinyl group substituent on the inner carbon atom of the N‐confused porphyrin ring. The spectroscopic data suggest that 1 exhibits an {Co(NO)}8 electronic structure. The nitrosylation of 1 in the presence of oxygen leads to [Co(CTPPO)(NO)] (3), which is a {Co(NO)}7 cobalt nitrosyl complex. A bent axial Co–N–O conformation was observed in both nitric oxide complexes with an angle of 128.5(7)° for 2 and 146.9(11)° for 3. An sp3 hydride carbon atom was evidenced in the crystal structure of 2, and an η2 interaction between the cobalt center and the inner carbonyl group was observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis and Characterization of Stable N‐Heterocyclic Plumbylenes
Authors: Hahn F. Ekkehardt , Heitmann Dennis , Pape Tania 
Published: January 2008

AbstractThe reaction of N,N′‐dialkyl‐1,2‐diaminobenzenes with bis[bis(trimethylsilyl)amido]lead(II) leads to the corresponding N‐heterocyclic plumbylenes (R = Me: 1; R = Et: 2; R = isobutyl: 3; R = neopentyl: 4). The steric demand of the N,N′‐dialkyl substituents determines the mode of aggregation of the plumbylenes. X‐ray diffraction analyses show both 3and 4 to form dimers in the solid state with intermolecular [η2‐(C6H4)···Pb]2 contacts for 3 and [η6‐(C6H4)···Pb]2 contacts for 4.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Syntheses, Structures and Magnetic Properties of Dinuclear Copper(II)–Lanthanide(III) Complexes Bridged by 2‐Hydroxymethyl‐1‐methylimidazole (Eur. J. Inorg. Chem. 5/2008)
Authors: Zhang Wei‐Xiong , Yang Yang‐Yi , Zai Shao‐Bo , Weng, Ng Seik , Chen Xiao‐Ming 
Published: January 2008

Abstractthe cover picture shows a cupric metalloligand, formed by the mixed O‐ and N‐atom donor ligand 2‐hydroxymethyl‐1‐methylimidazole, that further ligates to lanthanide ions, which results in dinuclear CuLn complexes. With different lanthanide ions (Gd3+, La3+, and Sm3+), the CuLn complexes have different structural features and exhibit ferromagnetic, paramagnetic and antiferromagnetic behavior, respectively. Details are discussed in the article by Y.‐Y. Yang, X.‐M. Chen et al. on p. 679 ff..
Miniaturizing free‐flow electrophoresis – a critical review
Authors: Kohlheyer Dietrich , Eijkel Jan C. T. , van den Berg Albert , Schasfoort Richard B. M. 
Published: January 2008

AbstractFree‐flow electrophoresis (FFE) separation methods have been developed and investigated for around 50 years and have been applied not only to many types of analytes for various biomedical applications, but also for the separation of inorganic and organic substances. Its continuous sample preparation and mild separation conditions make it also interesting for online monitoring and detection applications. Since 1994 several microfluidic, miniaturized FFE devices were developed and experimentally characterized. In contrast to their large‐scale counterparts microfluidic FFE (μ‐FFE) devices offer new possibilities due to the very rapid separations within several seconds or below and the requirement for sample volumes in the microliter range. Eventually, these μ‐FFE systems might find application in so‐called lab‐on‐a‐chip devices for real‐time monitoring and separation applications. This review gives detailed information on the results so far published on μ‐FFE chips, comprising its four main modes, namely free‐flow zone electrophoresis (FFZE), free‐flow IEF (FFIEF), free‐flow ITP (FFITP), and free‐flow field‐step electrophoresis (FFFSE). The principles of the different FFE modes and the basic underlying theory are given and discussed with special emphasis on miniaturization. Different designs as well as fabrication methods and applied materials are discussed and evaluated. Furthermore, the separation results shown indicate that similar separation quality with respect to conventional FFE systems, as defined by the resolution and peak capacity, can be achieved with μ‐FFE separations when applying much lower electrical voltages. Furthermore, innovations still occur and several approaches for hyphenated, more integrated systems have been proposed so far, some of which are discussed here. This review is intended as an introduction and early compendium for research and development within this field.
Evaluation of Various Unstructured Kinetic Models for the Production of Protease by Bacillus sphaericus MTTC511
Authors: Rajendran A. , Thangavelu V. 
Published: January 2008

AbstractBacillus sphaericus MTCC511 was used for the production of protease in submerged batch fermentation. Maximum protease activity of 1010 U/L was obtained during a fermentation period of 24 h under optimized conditions of 30 °C in a medium with an initial pH of 7 and at a shaking rate of 120 rpm. The maximum biomass obtained in the batch fermentation was 2.55 g/L after 16 h. Various unstructured models were analyzed to simulate the experimental values of microbial growth, protease activity and substrate concentration. The unstructured models, i.e. the Monod model for microbial growth, the Monod incorporated Luedeking‐Piret model for the production of protease and the Monod‐incorporated modified Luedeking‐Piret model for the utilization of substrate were capable of predicting the fermentation profile with high coefficient of determination (R2) values of 0.9967, 0.9402 and 0.9729, respectively. The results indicated that the unstructured models were able to describe the fermentation kinetics more effectively.
Study of the Operability of a Continuous Bioreactor for the Pre‐fermentation of Cheese Culture
Authors: Al‐Rabiah A. , Ajbar A. 
Published: January 2008

AbstractThe dynamics of a continuous stirred‐tank bioreactor for cheese pre‐fermentation is analyzed using elementary concepts of bifurcation theory and continuation techniques. The bioreactor model, which was previously developed and validated, explicitly incorporates the effect of uncontrolled pH levels. The stability analysis of the model is carried out for two cases: In the first case, the bioreactor is equipped with a seed tank, while the second case involves no additional seed tank. The static analysis allows useful analytical results for the study of steady state multiplicity of the model to be derived. The results of this paper provide practical guidelines on the selection of operating parameters that can eliminate difficult operating regions and that can consequently improve the operability of the bioreactor.