bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Rheological Behavior of Purely Viscous Fluids on Analytical Residence Time Distribution in Straight Tubes
Authors: Delaplace G. , Thakur R. K. , Bouvier L. , Leprêtre C. , Ilnyzckyj C. , André C. , Nouar C.
Published: January 2008

In an effort to better understand the homogeneity of heat treatment of foodstuffs in holding tubes, the cumulative residence time distribution function is derived for a Herschel‐Bulkley fluid from fully developed laminar flow in a straight circular tube under isothermal conditions when diffusional effects are negligible. The proposed analytical solution can be reduced to solutions for Newtonian, shear‐thinning, dilatant, Bingham fluids by setting particular rheological parameters, and consequently, it is possible to successfully explain the dependence of residence time distribution on fluid properties for almost all of the rheological models used for time‐independent purely viscous fluids.
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

A 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

A 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

The 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

Uniform 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

Für 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

Für 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

Exotherme 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

In 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

Im 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

BACKGROUND

Laser‐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.

METHODS

LIAF 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.

RESULTS

Histopathologic 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.

CONCLUSIONS

An 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

BACKGROUND

The 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.

METHODS

The study was a case series of 14 patients with cerebrospinal fluid (CSF)‐positive MM who were treated at a tertiary care university medical center.

RESULTS

Fourteen 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.

CONCLUSIONS

MM 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

BACKGROUND

Knowledge 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.

METHODS

The 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.

RESULTS

The 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.

CONCLUSIONS

The 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

We 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

The 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

The 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

the 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

Free‐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

Bacillus 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

The 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.
Proglacial sediment trapping in recently formed Silt Lake, upper Lillooet Valley, Coast Mountains, British Columbia
Authors: Schiefer Erik , Gilbert Robert
Published: January 2008

The sedimentology of proglacial Silt Lake was assessed by lake sediment coring and monitoring of lacustrine processes during a late‐summer period of high glacier melt to characterize sediment delivery from the heavily glacierized catchment and investigate the sediment trapping dynamics of this upland lake. A complete varve chronology was established for a distal basin of the lake which was exposed by Lillooet Glacier retreat between 1947 and 1962. The varve record showed decreasing sedimentation rates in the basin while the glacier retreated, and as the lake became free of ice contact in the early 1970s. Although recession has continued over recent decades, and glacier proximity to the lake has, therefore, continued decreasing, lacustrine sedimentation rates are now accelerating due to changing basin morphometry caused by delta progradation. Over shorter time scales, lake sedimentation patterns respond to changing runoff conditions, including late‐summer glacier melt intensity, intra‐annual flooding events, diumal runoff fluctuations, and within‐lake turbidity currents. Turbidity currents included quasi‐regular flows during high diurnal discharges and an episodic flushing of temporarily stored sediment from the sandur or delta at a time of low stage. Suspended sediment yield to Silt Lake is estimated to exceed 103 Mg km−2 a−1, a magnitude that surpasses previous local and regional yield estimates for the glacierized headwaters of the Lillooet River valley. Since Silt Lake currently traps a significant prooportion of that upland sediment supply, and the trapping efficiency of the basin has been variable at decadal time scales, the formation and continued development of Lilt Lake has likely had a significant influence on downstream sediment delivery. Lacustrine sediment‐based proxies of long‐term hydroclimatic variability being developed in glacially distal settings should include provisions for dynamic sediment trapping effects in upstream water bodies that often form in the active proglacial environment. Copyright © 2008 John Wiley & Sons, Ltd.
Mechanisms of hepatocyte growth factor–mediated and epidermal growth factor–mediated signaling in transdifferentiation of rat hepatocytes to biliary epithelium
Authors: Limaye Pallavi B. , Bowen William C. , Orr Anne V. , Luo Jianhua , Tseng George C. , Michalopoulos George K.
Published: February 2008

Previous studies from our laboratory have demonstrated that hepatocytes can transdifferentiate into biliary epithelium (BE) both

in vivo

and

in vitro

; however, the mechanisms are unclear. The current study was designed to investigate the mechanisms of hepatocyte transdifferentiation

in vitro

. Rat hepatocytes were cultured in roller bottles to obtain hepatocyte organoid cultures, which were stimulated with various growth factors (GFs) including hepatocyte growth factor (HGF), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), stem cell factor (SCF), macrophage-stimulating protein (MSP), fibroblast growth factor-a (FGF-a), fibroblast growth factor-b (FGF-b), and fibroblast growth factor-8b (FGF-8b). Only the cultures treated with HGF, EGF, and their combination exhibited formation of hepatocyte-derived biliary epithelium (BE) despite the presence and activation of all the pertinent cognate membrane receptors of the rest of the GFs. Microarray analysis of the organoid cultures identified specific up-regulation of approximately 500 target genes induced by HGF and EGF, including members of the extracellular matrix (ECM) protein family, Wnt/β-catenin pathway, transforming growth factor beta (TGF-β)/bone morphogenetic protein (BMP) pathway, and CXC (cysteine-any amino acid-cysteine) chemokines. To investigate the downstream signaling involved in hepatocyte to biliary epithelial cell (BEC) transdifferentiation, we investigated expression and activities of mitogen-activated protein (MAP) kinases [extracellular signal-regulated kinase (ERK)1/2, p38, and c-Jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK)] as well as serine/threonine kinase AKT. The analysis indicated that AKT phosphorylation was particularly increased in cultures treated with HGF, EGF, and their combination. Whereas phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 completely inhibited biliary epithelium formation, AKT inhibitor could only moderately reduce formation of BE in the organoid cultures treated with HGF+EGF. Most of the HGF+EGF target genes were altered by LY294002.

Conclusion:

Taken together, these data indicate that hepatocyte to BE transdifferentiation is regulated by HGF and EGF receptors and that PI3 kinase–mediated signaling independent of AKT is a crucial component of the transdifferentiation process.
β-Catenin deletion in hepatoblasts disrupts hepatic morphogenesis and survival during mouse development
Authors: Tan Xinping , Yuan Youzhong , Zeng Gang , Apte Udayan , Thompson Michael D. , Cieply Benjamin , Stolz Donna B. , Michalopoulos George K. , Kaestner Klaus H. , Monga Satdarshan P.S.
Published: February 2008

β-Catenin, the central component of the canonical Wnt pathway, plays important roles in the processes of liver regeneration, growth, and cancer. Previously, we identified temporal expression of β-catenin during liver development. Here, we characterize the hepatic phenotype, resulting from the successful deletion of β-catenin in the developing hepatoblasts utilizing Foxa3-cyclization recombination and

floxed
-β-catenin (exons 2 through 6) transgenic mice. β-Catenin loss in developing livers resulted in significantly underdeveloped livers after embryonic day 12 (E12) with lethality occurring at around E17 stages. Histology revealed an overall deficient hepatocyte compartment due to (1) increased cell death due to oxidative stress and apoptosis, and (2) diminished expansion secondary to decreased cyclin-D1 and impaired proliferation. Also, the remnant hepatocytes demonstrated an immature phenotype as indicated by high nuclear to cytoplasmic ratio, poor cell polarity, absent glycogen, and decreased expression of key liver-enriched transcription factors: CCAAT-enhancer binding protein-α and hepatocyte nuclear factor-4α. A paucity of primitive bile ducts was also observed. While the stem cell assays demonstrated no intrinsic defect in hematopoiesis, distorted hepatic architecture and deficient hepatocyte compartments resulted in defective endothelial cell organization leading to overall fetal pallor.

Conclusion:

β-Catenin regulates multiple, critical events during the process of hepatic morphogenesis, including hepatoblast maturation, expansion, and survival, making it indispensable to survival.
Caspase activation is associated with spontaneous recovery from acute liver failure
Authors: Volkmann Xandra , Anstaett Matthias , Hadem Johannes , Stiefel Penelope , Bahr Matthias J. , Lehner Frank , Manns Michael P. , Schulze-Osthoff Klaus , Bantel Heike
Published: February 2008

Acute liver failure (ALF) has various causes and is characterized by rapid hepatocyte dysfunction with development of encephalopathy in the absence of preexisting liver disease. Whereas most patients require liver transplantation to prevent the high mortality, some patients recover spontaneously and show complete liver regeneration. Because of the low incidence of ALF, however, the molecular mechanisms of liver dysfunction and regeneration are largely unknown. In this study, we investigated the role of apoptosis and caspases in 70 ALF patients using novel biomarkers that allow the detection of caspase activation in serum samples. Compared with healthy individuals, activation of caspases was strongly enhanced in ALF patients. Interestingly, patients with spontaneous recovery from ALF revealed a significantly higher activation of caspases than patients that required transplantation or died, although in the latter patients extensive DNA fragmentation and signs of nonapoptotic cell death were observed. In the spontaneous survivors, increased caspase activation was accompanied by elevated levels of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), important cytokines involved in liver regeneration.

Conclusion:

Our data suggest that caspase activation and apoptosis are involved in ALF of patients with spontaneous recovery, whereas caspase-independent cell death might be more relevant in irreversible forms of liver failure. These findings might be important for therapeutic options of ALF but also suggest that measurement of caspase activation might be of prognostic value to predict the outcome of acute liver failure.
Bioactivity and osteoblast response of the micro‐arc oxidized zirconia films
Authors: Han Yong , Yan Yuanyuan , Lu Chunguo , Zhang Yumei , Xu Kewei
Published: February 2008

Zirconia films containing Ca and P were prepared by micro‐arc oxidation (MAO) of zirconium. The microstructure, in vitro bioactivity, and primary osteoblast response of the films were investigated as a function of the applied voltages in the range of 400–500 V. The results indicate that the MAO‐formed zirconia films are porous and nanocrystalline, and predominantly composed of tetragonal zirconia (t‐ZrO2). The pores and grains sizes and t‐ZrO2 content of the films tend to increase with the applied voltages. The zirconia films formed at higher voltages have higher amount of CaO and phosphate and slightly lower amount of ZrOH groups. Although, all of the zirconia films can be fully covered by bone‐like apatite after immersion in simulated body fluids (SBF) within 10 days, there exists remarkable difference in apatite‐induced time. The apatite‐forming ability of the films is not only ascribed to ZrOH groups on the surfaces, but also enhanced by the CaO and phosphate ions incorporated into ZrO2. Osteoblasts on the films are observed to attach, proliferate, and grow in good state, and have good alkaline phosphatase activity. It is suggested that the MAO‐formed ZrO2 films exhibit favorable bioactivity and biocompatibility. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Peroxiredoxin 6 as an antioxidant enzyme: Protection of lung alveolar epithelial type II cells from H2O2‐induced oxidative stress
Authors: Wang Yan , Feinstein Sheldon I. , Fisher Aron B.
Published: February 2008

We evaluated the antioxidant role of peroxiredoxin 6 (Prdx6) in primary lung alveolar epithelial type II cells (AEC II) that were isolated from wild type (WT), Prdx6−/−, or Prdx6 transgenic (Tg) overexpressing mice and exposed to H2O2 at 50–500 µM for 1–24 h. Expression of Prdx6 in Tg AEC II was sevenfold greater than WT. Prdx6 null AEC II exposed to H2O2 showed concentration‐dependent cytotoxicity indicated by decreased “live/dead” cell ratio, increased propidium iodide (PI) staining, increased annexin V binding, increased DNA fragmentation by TUNEL assay, and increased lipid peroxidation by diphenylpyrenylphosphine (DPPP) fluorescence. Compared to Prdx6 null cells, oxidant‐mediated damage was significantly less in WT AEC II and was least in Prdx6 Tg cells. Thus, Prdx6 functions as an antioxidant enzyme in mouse AEC II. Prdx6 has been shown previously to reduce phospholipid hydroperoxides and we postulate that this activity is a major mechanism for the effectiveness of Prdx6 as an antioxidant enzyme. J. Cell. Biochem. 104: 1274–1285, 2008. © 2008 Wiley‐Liss, Inc.
Synthesis of [1,2‐3H]ethylamine hydrochloride and [3H]‐labeled apadenoson for a human ADME study
Authors: Hong Yang , Bonacorsi Samuel J. , Tian Yuan , Gong Sharon , Zhang Donglu , Humphreys W. Griffith , Balasubramanian Balu , Cheesman Edward H. , Zhang Zhiqin , Castner James F. , Crane Paul D.
Published: January 2008

Tritium‐labeled [1,2‐3H]ethylamine hydrochloride was prepared through a multiple‐step sequence in high radioactive specificity. The labeled amine was isolated in high purity following cartridge filtration and used subsequently in the synthesis of [N‐ethyl‐1,2‐3H]apadenoson, an adenosine A2a receptor agonist. The overall yield for this transformation was 56% and the radiochemical purity of the final product was greater than 99%. Copyright © 2008 John Wiley & Sons, Ltd.
Comparison of global gridded precipitation products over a mountainous region of Africa
Authors: Dinku T. , Connor S. J. , Ceccato P. , Ropelewski C. F.
Published: January 2008

Five gridded monthly precipitation products are evaluated using a gauge network over complex topography in Africa. The global gridded products considered are produced by the Global Precipitation Climatology Center (GPCC), NOAA Climate Prediction Center (NOAA–CPC), and the Climate Research Unit at the University of East Anglia (UEA–CRU). Three different products from GPCC are available at multiple spatial resolutions: 0.5, 1 and 2.5° ; the NOAA–CPC product has a spatial resolution of 2.5° while that of UEA–CRU is 0.5° . Comparisons of the GPCC and UEA–CRU products are carried out at spatial resolutions of 0.5, 1 and 2.5° , while NOAA–CPC is compared with the other products only at 2.5° resolution. There is very strong agreement between the gridded global products and the reference raingauge data. Average correlation coefficients are about 0.95, 0.92, and 0.90 at 2.5, 1.0 and 0.5° spatial resolutions, respectively. Both systematic and random errors are reasonably low. The performance of these products is highest during the wettest season (Jun–Aug), and relatively poor during the dry season (Dec–Feb). The seasonal differences are more prominent at high resolution. These results are very encouraging, particularly, when considering the complex terrain of the validation site. Copyright © 2008 Royal Meteorological Society
Prospective study of liver transplant recipients with HCV infection: Evidence for a causal relationship between HCV and insulin resistance
Authors: Delgado-Borrego Aymin , Liu Yun-Sheen , Jordan Sergio H. , Agrawal Saurabh , Zhang Hui , Christofi Marielle , Casson Deborah , Cosimi Benedict A. , Chung Raymond T.
Published: January 2008

An association between hepatitis C virus (HCV) infection and insulin resistance (IR) has been recently reported. However, causality has not been established. The cross-sectional nature of most reported studies and varying degrees of fibrosis have limited definitive conclusions about the independent role of HCV in development of IR. We sought to evaluate whether HCV induces IR by prospectively analyzing a cohort of adult liver transplant (LT) recipients. A total of 34 adults (14 HCV(+) and 20 HCV(−)) who underwent consecutive LT were followed during the first year posttransplantation. IR was estimated using the homeostasis model assessment (HOMA). Univariate and multivariate repeated measures analyses and Cox regression models were used. There were no significant differences between the groups with respect to age, body mass index (BMI), family history of diabetes, alcohol consumption, or laboratory indices. The cohort had no or minimal fibrosis. There was lower prednisone use in the HCV(+) group, and no difference in the use of tacrolimus between the two groups was found. IR was 77% higher in HCV(+) subjects during the first year post-LT when controlling for BMI (P = 0.035). Subjects with high HCV ribonucleic acid (RNA) levels reached high HOMA-IR significantly earlier than those with lower HCV RNA (P = 0.03). Following the first month post-LT, HCV(+) subjects were 4 times more likely to become diabetic than HCV(−) controls (P < 0.01). In conclusion, there is significantly higher IR in the HCV(+) group during the first year post-LT. This cannot be explained by differences in BMI, medications used, alcohol consumption, or degree of fibrosis. Higher HCV RNA levels were associated with earlier elevations in HOMA-IR. Collectively, these results provide strong evidence that HCV induces the development of IR. Liver Transpl, 2007. © 2007 AASLD.
Clinically recurrent primary sclerosing cholangitis following liver transplantation: A time course
Authors: Campsen Jeffrey , Zimmerman Michael A. , Trotter James F. , Wachs Michael , Bak Thomas , Steinberg Tracy , Kam Igal
Published: January 2008

Orthotopic liver transplantation (OLT) is the treatment of choice for patients with end-stage primary sclerosing cholangitis (PSC). This study sought to chronicle the natural history of PSC recurrence following OLT and identify clinical variables that may contribute to disease reemergence. From 1988 to 2006, 1102 OLTs were performed in 1032 adults at the University of Colorado Health Sciences Center. Of these, 130 patients (12.6%) with PSC received 146 allografts. Recurrence was defined by a clinically worsening examination and radiographic evidence. A total of 9 potential predictors were considered, using both bivariate log rank and multivariate Cox analysis, including: age > 55, gender, surgical technique (piggyback technique), presence of inflammatory bowel disease, intact colon before transplant, or cholangiocarcinoma (CCA), cold ischemia time, sirolimus-based immunosuppression, and graft type. The 1, 5, and 10-year recurrence-free survival was 91%, 76%, and 61%, respectively. The crude incidence of disease recurrence was 22 of 130 patients or 16.9%. Patients' risk of recurrent PSC at 1, 5, and 10 years was 2%, 12%, and 20%, respectively (mortality censored). Of the 22 patients that developed recurrent disease, 7 received a second transplant. Of the 9 factors considered, the presence of CCA prior to OLT is significantly predictive of disease recurrence [risk ratio (RR) = 3.77; P = 0.0038]. Once a patient was diagnosed with recurrent disease, the median survival without receiving a second transplant was 39.1 months (95% confidence interval: 27.6-50.6 months). In conclusion, recurrent PSC following OLT is a formidable but protracted problem following OLT. Patients may require a second transplant following reemergent disease with reasonable survival benefit. Liver Transpl 14:181–185. 2008. © 2008 AASLD.
Outcome of living donor liver transplantation for post-Kasai biliary atresia in adults
Authors: Kyoden Yusuke , Tamura Sumihito , Sugawara Yasuhiko , Yamashiki Noriyo , Matsui Yuichi , Togashi Junichi , Kaneko Junichi , Kokudo Norihiro , Makuuchi Masatoshi
Published: January 2008

Previous reports described the effectiveness of living donor liver transplantation (LDLT) for post-Kasai biliary atresia (BA) in the pediatric population. Information on the outcome of LDLT in patients that have reached adulthood after the Kasai procedure, however, is limited. A recent report postulated a poorer long-term outcome of LDLT in these adults. We reviewed our experience to evaluate the validity of this hypothesis. Between January 1996 and October 2006, 385 LDLTs were performed at our institution. There were 80 post-Kasai BA cases in the series; 60 (75%) were pediatric, and 20 (25%) were adults. There were no ABO blood type–incompatible cases. None were complicated with severe hepatopulmonary syndrome, portopulmonary hypertension, or hepatocellular carcinoma. The 5-year overall survival rates were 90% for the adults and 90% for the children (P > 0.99). The median follow-up period was 7 years in the adults and 11 years in the children. There was no donor mortality. The outcome of LDLT in adult post-Kasai BA patients in the present series was satisfactory; that is, adult and pediatric patient survival rates were not different. This finding suggests that for post-Kasai BA patients without serious comorbidity at the time of transplantation, LDLT can be performed safely in all age groups. Liver Transpl 14:186–192, 2008. © 2008 AASLD.
Risk factors for recurrence of primary sclerosing cholangitis after liver transplantation
Authors: Alexander Jacob , Lord James D. , Yeh Matthew M. , Cuevas Carlos , Bakthavatsalam Ramasamy , Kowdley Kris V.
Published: January 2008

Orthotopic liver transplantation (OLT) is the only effective treatment for end-stage liver disease due to primary sclerosing cholangitis (PSC). Recurrence of PSC has recently emerged as a leading cause of allograft failure in the long term. There is limited data on risk factors for recurrence of PSC. We performed a retrospective analysis of 69 consecutive patients who underwent a first OLT for PSC over a 14-year period. Baseline characteristics and clinical and laboratory test results post-LT were recorded. Cholangiograms and liver histopathology were reviewed in a blinded manner by an experienced radiologist and hepatopathologist. Recurrent PSC was diagnosed using previously published Mayo Clinic cholangiographic or histologic criteria. Of 69 patients, 7 (10%) developed recurrent PSC at a median of 68 months (range, 24-134 months) post-LT. The following variables were associated with recurrent PSC in our cohort: presence of human leukocyte antigen (HLA)-DRB1*08 (29% versus 2%; P= 0.026; odds ratio [OR], 24.4; 95% confidence interval [CI], 1.8-318.1), acute cellular rejection (ACR) (71% versus 22%; P= 0.015; OR, 8.7; 95% CI, 1.5-49.9), and steroid-resistant ACR (29% versus 0%; P= 0.012). Despite the strong linkage disequilibrium between DRB1*08 and DQB1*04, DRB1*08-positive subjects with recurrence were negative for DQB1*04, whereas the single DRB1*08-positive subject without recurrent PSC was positive for DQB1*04. A history of ACR and presence of HLA-DRB1*08 are associated with increased risk of recurrent PSC, suggesting an immunologic mechanism for this syndrome. Further studies are required to confirm these observations and to understand the underlying mechanisms. Liver Transpl 14:245–251. 2008. © 2008 AASLD.
A constructive version of Birkhoff's theorem
Authors: Carlström Jesper
Published: January 2008

A version of Birkhoff's theorem is proved by constructive, predicative, methods. The version we prove has two conditions more than the classical one. First, the class considered is assumed to contain a generic family, which is defined to be a set‐indexed family of algebras such that if an identity is valid in every algebra of this family, it is valid in every algebra of the class. Secondly, the class is assumed to be closed under inductive limits. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Real numbers and other completions
Authors: Richman Fred
Published: January 2008

A notion of completeness and completion suitable for use in the absence of countable choice is developed. This encompasses the construction of the real numbers as well as the completion of an arbitrary metric space. The real numbers are characterized as a complete Archimedean Heyting field, a terminal object in the category of Archimedean Heyting fields. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A constructive semantics for non‐deducibility
Authors: Ciraulo Francesco
Published: January 2008

This paper provides a constructive topological semantics for non‐deducibility of a first order intuitionistic formula. Formal topology theory, in particular the recently introduced notion of a binary positivity predicate, and co‐induction are two needful tools. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Resolution of the uniform lower bound problem in constructive analysis
Authors: Palmgren Erik
Published: January 2008

In a previous paper we constructed a full and faithful functor ℳ︁ from the category of locally compact metric spaces to the category of formal topologies (representations of locales). Here we show that for a real‐valued continuous function f, ℳ︁(f) factors through the localic positive reals if, and only if, f has a uniform positive lower bound on each ball in the locally compact space. We work within the framework of Bishop constructive mathematics, where the latter notion is strictly stronger than point‐wise positivity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)