bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vom Einzeltropfen zur Extraktionskolonne
Authors: Bart Hans‐Jörg , Garthe Daniel , Grömping Tobias , Pfennig Andreas , Schmidt Stephan , Stichlmair Johann 
Published: May 2006

AbstractIm Rahmen eines AiF‐Verbundprojektes wurde ein neues Konzept für die Auslegung von Extraktionskolonnen bei der Flüssig/Flüssig‐Extraktion entwickelt. Dieses Auslegungskonzept basiert auf Messungen an einzelnen bzw. wenigen Tropfen in standardisierten Messzellen im Labormaßstab. Für unterschiedliche Stoffsysteme wurden Ansätze zur Modellierung des Stofftransports, der Sedimentation, der Tropfenspaltung und ‐koaleszenz anhand solcher Messungen validiert. Auf diesen Detailmodellen aufbauend wurden Simulations‐Werkzeuge für gerührte und pulsierte Kolonnen entwickelt, die eine genaue Vorhersage des Kolonnenverhaltens erlauben. Abschließend konnte gezeigt werden, dass diese Methode auch für Aufgabenstellungen aus der industriellen Praxis mit technischen Stoffsystemen eine exzellente Beschreibung erlaubt.
Abtrennung von Arsen und anderer Schwermetalle mit imprägnierten Adsorberpolymeren – Teil 1: Synthese der Imprägnierungsmittel und Abtrennung von Arsen
Authors: Grobosch T. , Mickler W. , Feistel L. , Schilde U. 
Published: May 2006

AbstractFünfwertiges Arsen kann am effektivsten in Form seiner Oxoanionen aus schwach alkalischen Lösungen mittels stark basischer Ionenaustauscher abgetrennt werden. Der Nachteil dieser Methode besteht darin, dass die Arsenabtrennung nicht selektiv erfolgt. Um weitere Möglichkeiten zu testen, wird auf das Konzept der Imprägnierung polymerer Materialien mit spezifischen Extraktionsmitteln zurückgegriffen. Imprägniert wird nach der „Dry‐Impregnation‐Method”︁, von der aufgrund der Hydrophobizität der Imprägnierungsmittel ein hoher Beladungsgrad der Adsorber mit diesen Reagenzien erwartet werden kann. Dabei soll geprüft werden, ob der Beladungsgrad der imprägnierten Adsorberpolymere durch den Einsatz verschiedener Lösungsmittel optimiert werden kann.
Pulsationsarmer Laborverdampfer für kleine Flüssigkeitsströme
Authors: Freund A. , Friedrich G. , Merten C. , Eigenberger G. 
Published: May 2006

AbstractEine kontrollierte und kontinuierliche Totalverdampfung kleiner und mittlerer Flüssigkeitsströme ist in vielen technischen Anwendungen erforderlich. Als Beispiele kann die gezielte Dosierung von Flüssigkeitsdampf in Labor‐ und Technikumsanlagen oder in kleintechnischen Produktionsanlagen genannt werden. Eine möglichst pulsationsfreie Totalverdampfung der zugeführten Flüssigkeit mit schnellem Ansprechverhalten auf Lastwechsel ist dabei eine wichtige Forderung.
Einfluss der Morphologie auf Stofftransport und ‐umsatz in Aspergillus niger‐Pellets
Authors: Hille A. , Neu T. R. , Hempel D. C. , Horn H. 
Published: May 2006

AbstractSowohl der Stofftransport als auch der Stoffumsatz in Pilzpellets von Aspergillus niger AB 1.13 werden in hohem Maß von der Pelletmorphologie bestimmt. Hierbei ist insbesondere die Struktur des Pelletrandbereiches aufgrund der begrenzten Eindringtiefe des Substrats Sauerstoff entscheidend für die Umsatzleistung. Durch die Kombination von konfokaler Laser‐Scanning‐Mikroskopie und digitaler Bildanalyse kann die Biomasseverteilung innerhalb eines Pellets radial quantifiziert werden. Es zeigt sich, dass Pellets mit ähnlicher mittlerer Biotrockenmassedichte sehr unterschiedliche Hyphenverteilungen über den Pelletradius aufweisen können. In diesen Pellets gemessene, örtlich aufgelöste Sauerstoffkonzentrationsprofile spiegeln diesen Unterschied deutlich wider, wohingegen herkömmliche morphologische Parameter wie die mittlere Biotrockenmassedichte einen solchen Unterschied in der Sauerstoffversorgung der Aggregate nicht vorhersagen.
Redox‐Active 17‐ and 19‐Membered Metallamacrocycles Incorporating Tetrathiafulvalene
Authors: Gachot Grégory , Pellon Pascal , Roisnel Thierry , Lorcy Dominique 
Published: May 2006

AbstractRedox‐active 17‐ and 19‐membered metallamacrocycles were prepared thanks to the chelating ability of bis[(diphenylphosphane)alkylthio]TTF towards the M(CO)4 fragment(M = Mo, W). The TTF unit can adopt either a cis or a trans configuration as can the phosphorus atoms coordinated to the metal center. Moreover, an element of planar chirality is generated by the trans isomer of the TTF. Thus, the reaction affords six stereoisomers as evidenced by 31P NMR and X‐ray crystallographic analyses. The electrochemical properties of the title compounds have been investigated by cyclic voltammetry. Within the 19‐membered metallamacrocycles, no significant influence of the two redox moieties was detected, whereas in the 17‐membered metallamacrocycles, the oxidized TTF modifies the redox behavior of the metal center. Two crystalline complexes obtained with tetracyanoquinodimethane (TCNQ) and the tungsten 17‐ and 19‐membered metallamacrocycles are reported. Comparison of the crystal structures shows that these metallamacrocycles appear to be rather flexible even with strained structures.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
A TTF–TCNQ Electrode as a Voltammetric Analogue of an Ion‐Selective Electrode
Authors: Cano Manuel , Palenzuela Beatriz , Rodríguez‐Amaro Rafael 
Published: May 2006

AbstractA TTF‐TCNQ/PVC composite electrode is proposed as a voltammetric cation and anion sensor. The electrode relies on the principle that, during redox processes involving the TCNQ0/− couple for cations and the TTF+/0 couple for anions, electrolyte ions are included into lattice sites in the charge neutralization process. This voltammetric ion‐sensor provides results that are similar to those of sensors based on two electrodes (viz. one modified with TCNQ for cations and another modified with TTF for anions) but with some practical advantages over them.
Contribution to studies on calculation of the magnetic field under power lines
Authors: Budnik K. , Machczyński W. 
Published: May 2006

AbstractThe paper presents in a tutorial manner a theoretical study of the calculation of magnetic fields in vicinity of overhead electric power lines. Exact and simplified methods of the determination of the magnetic field of a straight overhead conductor based on the Fourier transform technique and on the concept of complex ground return plane are presented. The decomposition of the magnetic fields in two components: magnetic field obtained in free space from the Biot‐Savart law and the magnetic field produced by earth current is discussed. It is shown that in practical cases the effects from earth currents can be neglected as compared with effects from line currents. A solution for modeling magnetic fields produced by sagging conductor, described by the catenary equation, is also proposed. The effect of the catenary on the magnetic field spatial distribution is investigated. The calculation results of magnetic field produced by sagging conductor and the magnetic field of a conventional model consisting of a horizontal conductor hanging on the effective height lying between the maximum and minimum heights of catenaries is compared and discussed. As an example the magnetic field of a real‐power catenary high voltage 2 × 220 kV power line is demonstrated. Copyright © 2006 John Wiley & Sons, Ltd.
Survivin in esophageal cancer: An accurate prognostic marker for squamous cell carcinoma but not adenocarcinoma
Authors: Rosato Antonio , Pivetta Michela , Parenti Anna , Iaderosa Gaetano A. , Zoso Alessia , Milan Gabriella , Mandruzzato Susanna , Bianco Paola Del , Ruol Alberto , Zaninotto Giovanni , Zanovello Paola 
Published: May 2006

AbstractWe quantified the expression of survivin, both as mRNA in real‐time PCR and protein in immunohistochemistry, in tumor samples of 112 patients with esophageal cancer (56 squamous cell carcinomas and 56 adenocarcinomas). Overall survival of squamous cell carcinoma patients with high survivin mRNA levels was significantly less than that of patients with low survivin mRNA levels (p = 0.0033). Distribution pattern of survivin (nuclear vs. cytoplasmic or mixed) was not correlated to survival, while the extent of immunostaining was significantly correlated to survivin mRNA values (p = 0.016) and had prognostic relevance in univariate analysis (p = 0.0012). Cox's proportional‐hazard regression model showed that tumor survivin expression in esophageal squamous cell carcinoma was the most important prognostic factor, independent of tumor stage and other histopathological factors, both as mRNA relative value (p = 0.0259) and protein immunostaining (p = 0.0147). In esophageal adenocarcinoma, survivin expression and pattern of distribution had no prognostic relevance. Thus, quantifying survivin expression provides a prognostic marker only for esophageal squamous tumors. © 2006 Wiley‐Liss, Inc.
NNK activates ERK1/2 and CREB/ATF‐1 via β‐1‐AR and EGFR signaling in human lung adenocarcinoma and small airway epithelial cells
Authors: E. Laag , M. Majidi , M. Cekanova , T. Masi , T. Takahashi , H.M. Schuller 
Published: May 2006

AbstractWe have shown that the tobacco nitrosamine 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone (NNK) is an agonist for β‐adrenergic receptors (β‐ARs) and increased DNA synthesis of human lung adenocarinoma cells with features of bronchiolar Clara cells by binding to these receptors. Using a cell line derived from a human pulmonary adenocarcinoma with Clara cell phenotype (PACC) and immortalized human small airway epithelial cells (HPLD1), the putative cells of origin of this cancer type, our current studies have analyzed signaling initiated by binding of NNK to the β1‐AR. NNK upregulated ERK1/2 and CREB/ATF‐1 phosphorylation in a PKA‐dependent manner in both cell lines. This response was further increased by transient overexpression of the β1‐AR. Pre‐exposure of cells to the selective β1‐AR antagonist, atenolol, attenuated the stimulatory effects of NNK, suggesting the latter upregulated ERK1/2 and CREB/ATF‐1 via this receptor. In vivo labeling and immunoprecipitation assays revealed that NNK phosphorylated the epidermal growth factor receptor (EGFR) at tyrosine residues, 991, 1068 and 1173, an effect inhibited by atenolol. The inhibitor of EGFR‐specific tyrosine kinases, AG1478, reduced NNK ability to stimulate ERK1/2 and CREB/ATF‐1. Genomic analysis of the exons 18–21 of the EGFR genes showed that no mutations were present in either gene. Collectively, our data provide evidence, for the first time, that NNK targets ERK1/2 and CREB/ATF‐1 proteins via dual signaling involving β1‐AR and EGFR pathways in PACCs and their putative cells of origin. © 2006 Wiley‐Liss, Inc.
Chemokines and cancer
Authors: Zlotnik Albert 
Published: May 2006

AbstractThe chemokines and their receptors are a superfamily of small secreted molecules that control the migration of many cell types in the body. Several years ago it became clear that some chemokines and receptors regulate the migration of certain cells in the lymphoid system, and this raised the possibility that chemokines could also control the migration of tumor cells in the body. Breast cancer cells were found to express chemokine receptors in a nonrandom manner, and these observations pointed to several chemokine/receptor pairs that control tumor‐cell migration. The most important ligand/receptors pairs in these phenomena include CXCL12/CXCR4 and CCL21/CCR7. Since then, there has been intense interest in this area and many studies have been published, especially on CXCR4. These studies point to the following conclusions: (i) Tumors express chemokine receptors in a nonrandom manner. (ii) CXCR4 is the most widely expressed chemokine receptor in many different cancers. (iii) CCR7 is also expressed by many cancers, and is likely to mediate metastasis to the lymph nodes in selected cancers. (iv) The effects of CXCL12 on CXCR4‐bearing tumor cells likely include many other functions (growth, differentiation) besides migration. During normal development, the interaction CXCL12/CXCR4 is known to be involved in organogenesis. This process shares many characteristics with metastasis, and represents one of the key areas of future research. © 2006 Wiley‐Liss, Inc.
Methotrexate resistance in vitro is achieved by a dynamic selectionprocess of tumor cell variants emerging during treatment
Authors: de Anta Josep M. , Mayo Clara , Solé Francesc , Salido Marta , Espinet Blanca , Corzo Cristina , Petzold Myriam , Villa Olaya , Serrano Sergi , Real Francisco X. , Mayol Xavier 
Published: May 2006

AbstractGenetic instability leads to tumor heterogeneity, which in turn provides a source of cell variants responsible for drug resistance. However, the source of resistant cells during the process of acquired resistance is poorly understood. Our aim has been to characterize the mechanism by which acquired resistance to methotrexate emerges during the course of cancer cell treatment in vitro. We recently demonstrated that, in vitro, HT‐29 colon cancer cells become transiently sensitive to methotrexate by depleting the extracellular milieu of survival factors; on the other hand, the cell population under treatment can reversibly adapt to grow below a critical cell density in the presence of the drug. Here, we show that this adapted cell population gives rise to permanent resistant populations through repeated cycles of cell death and growth. This increased cell turnover, but not merely cell proliferation, is required for the appearance of increasing degrees of stable resistance that are progressively selected by drug pressure. Such a process, taking place in multiple steps, is here designated “dynamic selection.” The analysis of sensitive and resistant HT‐29 cell populations revealed that methotrexate induces genomic instability—characterized by centrosome amplification and aberrant chromosome recombination—leading to a low‐level amplification of the 5q chromosome arm as one of the earliest genetic events selected during treatment. Therefore, this model provides a mechanism by which a tumor cell population lacking resistant subpopulations before treatment is able to acquire the genetic changes required for stable drug resistance. © 2006 Wiley‐Liss, Inc.
Regulation of lipocalin‐2 gene by the cancer chemopreventive retinoid 4‐HPR
Authors: Caramuta Stefano , De Cecco Loris , Reid James F. , Zannini Laura , Gariboldi Manuela , Kjeldsen Lars , Pierotti Marco A. , Delia Domenico 
Published: May 2006

AbstractN‐(4‐Hydroxyphenyl)retinamide (4‐HPR) is a nonclassical retinoid with cancer preventive effectsin vivoand antiproliferative and apoptotic activitiesin vitro. Examining the transcriptional profile of human breast cancer cell lines, MCF7 and T47D, treated with 4‐HPR, we identified the lipocalin memberLCN2(NGALor24p3) as a gene, markedly induced by the retinoid. Because of its presumed function in apoptosis,LCN2was examined more thoroughly in response to 4‐HPR. Like mRNA, the expression of LCN2 protein in MCF7 and T47D cells was highly induced in a time‐dependent manner by 4‐HPR, but not by its inactive metabolite 4‐MPR and, to some extent, this event was linked to the free radicals normally generated by 4‐HPR. All‐trans retinoic acid also induced LCN2 protein, particularly in T47D cells. Ectopic LCN2 compromised cell viability, and the few MCF7 clones that survived LCN2 overexpression were less sensitive than do mock cells to 4HPR, indicating that selective pressure for survival to LCN2 confers cross‐resistance to 4‐HPR. Significantly, ablation of LCN2 induction by siRNA did not modify the response to 4‐HPR, implying that LCN2 is not critical for apoptosis by 4‐HPR. Our results indicate that 4‐HPR markedly induces LCN2 expression, but this event may not represent an apoptotic response. © 2006 Wiley‐Liss, Inc.
Inhibition of connective tissue growth factor by siRNA prevents liver fibrosis in rats
Authors: Li Guangming , Xie Qing , Shi Yi , Li Dingguo , Zhang Mingjun , Jiang Shan , Zhou Huijuan , Lu Hanming , Jin Youxin 
Published: May 2006

AbstractBackgroundConnective tissue growth factor (CTGF) is a highly profibrogenic molecule implicated in hepatic fibrogenesis. Small interfering RNA (siRNA) is an effective tool to silence gene expression post‐transcriptionally. Therefore, we conducted an investigation to determine if intraportal vein siRNA injection targeting CTGF inhibits CTGF expression on rat liver in vivo and furthermore whether it protects the liver from liver fibrosis.MethodsSome rats received carbon tetrachloride (CCl4) by subcutaneous injections every three days for six consecutive weeks, and meantime they also obtained either siRNA (0.1 mg/kg) targeting CTGF, saline or a control siRNA by intraportal vein injection to rats' liver at the same pattern. Other rats received CCl4 by subcutaneous injection for 2 weeks, followed by CCl4 and CTGF siRNA intraportal vein injection for four more weeks.ResultsIntraportal vein injection of CTGF siRNA specifically reduced the expression of CTGF protein in rat liver, and these effects were maintained for 3 days. Six weeks after CCl4 injection, prominent upregulations were observed in the gene expressions of CTGF, type I, III collagen, laminin, tissue inhibitor metal proteinase‐1 (TIMP‐1) and transforming growth factor‐β1 (TGF‐β1) in saline or control siRNA‐treated rats livers. Administrating CTGF siRNA for 4 or 6 weeks, by contrast, markedly attenuated the induction of CTGF, type I, III collagen, laminin, TIMP‐1 and TGF‐β1 genes, whereas Smad2, 7 gene expression was not affected. The number of active hepatic stellate cells (HSCs) determined by the expression of α‐smooth muscle actin was also significantly decreased. The CTGF siRNA treatment markedly reduced serum procollagen type III, hepatic hydroxyproline and liver fibrosis staging.ConclusionsSilencing CTGF expression with siRNA demonstrates therapeutic potential to prevent liver fibrosis by inhibiting HSC activation with consequent extracellular matrix accumulation and the upregulation of TGF‐β1 gene expression. Copyright © 2006 John Wiley & Sons, Ltd.
Applications of functional magnetic resonance imaging in psychiatry
Authors: Mitterschiffthaler Martina T. , Ettinger Ulrich , Mehta Mitul A. , Mataix‐Cols David , Williams Steve C.R. 
Published: May 2006

AbstractWhile the use of MRI techniques has become a cornerstone of the neurology clinic, the application of such methods in psychiatry was rather limited until the advent of functional magnetic resonance imaging (fMRI). Over the past decade fMRI has superseded radionuclide‐imaging techniques and blossomed into a widely used psychiatric research tool. This review focuses on the neurobiological findings from fMRI research in three less well‐documented psychiatric disorders: attention deficit hyperactivity disorder (ADHD), depression, and obsessive‐compulsive disorder (OCD). Although there was some disparity in early findings, greater standardization of image acquisition, analysis, and paradigms, and improved clinical classification are leading to a greater convergence of observations from different laboratories. fMRI is also beginning to realize its potential as an important mediator between genes and phenotypes, and may thus contribute to a better understanding of the pathophysiology of major neuropsychiatric diseases. The role of fMRI in the objective assessment of therapeutic intervention and early prediction of response to treatment is also discussed. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
A synoptic climatology of tropospheric ozone episodes in Sydney, Australia
Authors: Hart Melissa , De Dear Richard , Hyde Robert 
Published: May 2006

AbstractConcentrations of tropospheric ozone often exceed Australian air quality goals in Sydney during summer. However, features in the occurrence of ozone in Sydney are yet to be fully explained. Meteorological conditions associated with ozone episodes in Sydney are caused by complex interactions between synoptic and meso‐scale processes. This paper discusses the meteorological influences behind ozone pollution episodes in Sydney.A synoptic climatology of ozone episodes in Sydney was generated using multivariate statistical techniques, including principal component analysis (PCA) and a two‐stage cluster analysis, to classify days into meteorologically homogeneous synoptic categories. Surface and upper air meteorological data for warm months (Oct–Mar) over a 10‐year period were used as input into the statistical analyses. Eleven synoptic categories were identified in Sydney during the warm season and ozone concentrations associated with each of the synoptic categories were investigated. One synoptic category was found to be associated almost exclusively with high pollution concentrations. High ozone concentrations were found to be associated with a high‐pressure system located in the middle to eastern Tasman Sea producing light northwesterly gradient winds, an afternoon sea breeze, high afternoon temperatures, a shallow mixing height at the coast and warming aloft during the day.Over 90% of all days exceeding current air quality goals for ozone in Sydney fell within the synoptic category associated with the highest ozone concentrations. It is envisaged that results from this research will be useful to Australian regulatory bodies from both a forecast point of view and for the siting of future ozone precursor sources in Sydney and surrounding regions. Copyright © 2006 Royal Meteorological Society
Bitterness of saponins and their content in dry peas
Authors: Heng Lynn , Vincken Jean‐Paul , van Koningsveld Gerrit , Legger Aagje , Gruppen Harry , van Boekel Tiny , Roozen Jacques , Voragen Fons 
Published: May 2006

AbstractThe bitterness of a saponin mixture (containing saponin B and DDMP (2,3‐dihydro‐2,5‐dihydroxy‐6‐methyl‐4H‐pyran‐4‐one) saponin in a ratio of 1:4) and saponin B obtained from dry peas were established by a trained panel using line scaling. Both saponins were found to be bitter. However, the saponin mixture, and hence DDMP saponin, was found to be significantly more bitter than saponin B. The bitterness perceived correlated with the saponin concentration. In addition to saponin bitterness, the saponin content and composition of 16 dry pea varieties were also investigated. In two varieties, DDMP saponin was the only saponin present whereas, in the rest of the varieties, DDMP saponin was more abundant than saponin B. The pea varieties investigated differed significantly in saponin content. The amounts of DDMP saponin ranged from 0.7 to 1.5 g kg−1 (dry matter), whereas those of saponin B ranged from 0 to 0.4 g kg−1. As saponins are bitter, pea varieties with lower saponin contents would be preferred for use in food production. Copyright © 2006 Society of Chemical Industry
Possibilities and limitations of fast GC with narrow‐bore columns
Authors: Dömötörová Milena , Kirchner Michal , Matisová Eva , de Zeeuw Jaap 
Published: May 2006

AbstractIn this work, two narrow‐bore capillary columns with different internal diameters (I.D.) 0.15 mm (15 m length, 0.15 μm film thickness) and 0.10 mm (10 m length, 0.10 μm film thickness) with the same stationary phase (5% diphenyl 95% dimethylsiloxane), phase ratio and separation power were compared with regard to their advantages, practical limitations and applicability in fast GC on commercially available instrumentation. The column comparison concerns fast GC method development, speed and separation efficiency, the sample transfer into the column utilizing split and splitless inlet, sample capacity, detection (analysing compounds of a wide range of polarities and volatilities – even n‐alkanes C16–C28 and selected pesticides) and ruggedness (in the field of ultratrace analysis of pesticide residues in real matrix). Under conditions corresponding to speed/separation efficiency trade‐off 0.10 mm I.D. versus 0.15 mm I.D. column provides a speed gain of 1.74, but all other parameters investigated were better for the 0.15 mm I.D. column concerning more efficient sample transfer from inlet to the column using splitless injection, no discrimination with split injection. Better sample capacity (three times higher for the 0.15 mm than for the 0.10 mm I.D. column) resulted in improved ruggedness and simpler fast GC‐MS method development.