bluuebunny/crossref_metadata_2025 huggingface dataset:
Behaviour of concrete structures in fire
Authors: Fletcher Ian , Welch Stephen , Torero José , Carvel Richard , Usmani Asif
Published: July 2007

This paper provides a "state-of-the-art" review of research into the effects of high temperature on concrete and concrete structures, extending to a range of forms of construction, including novel developments. The nature of concrete-based structures means that they generally perform very well in fire. However, concrete is fundamentally a complex material and its properties can change dramatically when exposed to high temperatures. The principal effects of fire on concrete are loss of compressive strength, and spalling - the forcible ejection of material from the surface of a member. Though a lot of information has been gathered on both phenomena, there remains a need for more systematic studies of the effects of thermal exposures. The response to realistic fires of whole concrete structures presents yet greater challenges due to the interactions of structural elements, the impact of complex small-scale phenomena at full scale, and the spatial and temporal variations in exposures, including the cooling phase of the fire. Progress has been made on modeling the thermomechanical behavior but the treatment of detailed behaviors, including hygral effects and spalling, remains a challenge. Furthermore, there is still a severe lack of data from real structures for validation, though some valuable insights may also be gained from study of the performance of concrete structures in real fires. .
Oxidation stability and risk evaluation of biodiesel
Authors: Hoshino Takashi , Iwata Yusaku , Koseki Hiroshi
Published: July 2007

This review describes oxidation and thermal stability and hazardous possibility of biodiesel by auto-oxidation. As it can be distributed using today?s infrastructure biodisel production has increased especially in the European Union. Biodiesel has many surpassing properties as an automotive fuel. Biodiesel is considered safer than diesel fuel because of the high flash point, but it has oxygen and double bond(s). Fatty acid methyl esters are more sensitive to oxidative degradation than fossil diesel fuel. The ability of producing peroxides is rather high, therefore we should care of handling of biodiesel.
Fire suppression studies
Authors: Novozhilov Vasily
Published: July 2007

The paper presents overview of the current state of fire suppression studies. Focus is made on water-based fire protection technology, such as sprinklers and mist systems. Mechanisms of suppression and performance of different types of systems are discussed. Both experimental studies and mathematical modeling techniques are reviewed. In particular, computational fluid dynamics models available for simulation of water sprays are discussed in more detail.
Gis-based computer code for the evaluation of forest fire spread
Authors: Karpov Alexander , Telitsyn Henry , Efimova Nadezhda , Berdonosov Victor , Popovich Sergey
Published: July 2007

The approach to the implementation of a computer code, based on the geographic information system, for the forest fire behavior prediction is presented. Consecutive steps are considered, which include the formulation of fire spread mathematical model, classification of vegetation fuels using the forest inventory data, approximation of fire perimeter propagation, and overall arrangement of fire simulation code. .
Managing Human Resources in Order to Promote Knowledge Management and Technical Innovation
Authors: Jiménez‐Jiménez Daniel , Sanz‐Valle Raquel
Published: July 2007

Recent literature has highlighted the importance of human resource management, knowledge management, and technical innovation as key elements for achieving competitive advantage. Furthermore, research has shown a positive relationship between these three variables. However, empirical research on this issue is still scarce. This paper analyzes those linkages using structural equation modeling with data collected from 373 Spanish firms. The findings show that there is a relationship among the variables, although it is more complex than described in previous studies.
Three‐phase oil–water–gas horizontal co‐current flow part II. Holdup measurement and prediction
Authors: Spedding P. L. , Donnelly G. F. , Benard E.
Published: July 2007

Holdup data are presented for three‐phase co‐current oil‐water‐air in a horizontal 0.0259 m i.d. pipe. Detailed two‐phase studies confirmed the validity of the experimental technique employed. A model is presented for the prediction of oil‐air two‐phase holdup. The three‐phase holdup values were shown to be flow regime dependent and could be qualitatively explained on the basis of the fine structure of the liquid phases. A model is presented for the prediction of three‐phase liquid holdup. This work extends the regime study by Spedding et al. (Trans. Inst. Chem. Eng, Part A, Chem. Eng. Res. Des. 2005, 83A: 401–411) to holdup measurement and prediction for three‐phase flow. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
Re‐entrainment of wall deposits from a laboratory‐scale spray dryer
Authors: Hanus M. J. , Langrish T. A. G.
Published: July 2007

This work has determined the magnitude of re‐entrainment and established the operational parameters that may be manipulated to influence re‐entrainment of salt particles for a small‐scale spray dryer (Buchi B‐290). The wetness of the spray dryer wall deposits was found to significantly influence the magnitude of re‐entrainment. It was shown both experimentally and numerically that wet deposits form at low nozzle air‐to‐liquid ratios (<2000), which form large droplets that dry slowly, while the initial droplet velocity did not have a large influence on wet deposition. Wet deposits form strong liquid and solid bridges, and thus deposits formed from wet particles were difficult to re‐entrain. Less than 2% of deposits formed at nozzle air‐to‐liquid ratios less than 2000 were re‐entrained, while 15.4 to 21.2% of dry deposited particles (formed at nozzle air‐to‐liquid ratios ranging from 2308 to 3409) were re‐entrained. The threshold re‐entrainment velocity of sodium chloride particles in the Buchi B‐290 spray dryer was found to be between 4 and 7.7 ms−1, which is consistent with the lower‐end threshold velocities presented in the literature. No significant trend relating relative humidity to the magnitude of re‐entrainment was found in the 0.2–7.4% average relative humidity range, suggesting that the adhesive forces in spray dryer wall deposits are fairly constant across this relative humidity range. Decreasing wall deposit wetness through use of high (>2000) nozzle air‐to‐liquid ratios and use of high main gas velocities increased the re‐entrainment of wall deposits in this spray dryer. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
Time–temperature dependence of the electrical resistivity of high‐density polyethylene/carbon black composites
Authors: Traina Matteo , Pegoretti Alessandro , Penati Amabile
Published: July 2007

Several carbon blacks with surface areas from 105 to 1353 m2/g were used to produce composites through melt compounding with a high‐density polyethylene matrix. The electrical behavior of the obtained composites was investigated by the measurement of their resistivity as a function of the carbon black content and type at various temperatures and times during isothermal annealing treatments. The percolation threshold markedly decreased as the carbon black surface area increased, reaching a minimum value of 1.8 vol % for the carbon black with a surface area of 1353 m2/g. The resistivity passed through a maximum as the test temperature increased. Moreover, the analysis of the experimental data evidenced that the host high‐density polyethylene matrix and the conductive carbon black network rearranged during the isothermal thermal treatments, causing a resistivity decrease. This rearrangement became less and less important as the carbon black surface area increased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Curing behavior of a novel polytriazole resin
Authors: Wan Liqiang , Tian Jianjun , Huang Jianzhi , Hu Yanhong , Huang Farong , Du Lei
Published: July 2007

The curing behavior of a novel low temperature curing polytriazole resin, prepared from p‐xylylene diazide and N,N,N′,N′‐tetrapropargyl‐p,p′‐diaminodiphenylmethane, was investigated by DSC and rheological analyses. The kinetics of the curing of the resin was studied by nonisothermal and isothermal DSC measurements and the kinetics parameters were obtained. The values of apparent activation energy Ea of the curing reaction obtained by nonisothermal and isothermal DSC are 80.7 and 75.3 kJ/mol, respectively. The curing of the resin was traced by the isothermal rheological analysis. The gelation times of the resin at 70, 75, 80, and 85°C are about 200, 150, 110, and 75 min, respectively. The viscosity equation for the resin was found as follows:
$ \ln \eta= -107 + {{33.5 \times 10^3} \over T} + t \exp \left(26.3 + {{9.87 \times 10^3} \over T}\right). $
© 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Recycled PET‐organoclay nanocomposites with enhanced processing properties and thermal stability
Authors: Kráčalík Milan , Studenovský Martin , Mikešová Jana , Kovářová Jana , Sikora Antonín , Thomann Ralf , Friedrich Christian
Published: July 2007

Preparation of thermally stable recycled PET‐organoclay nanocomposites with improved processing and mechanical properties is a challenging task from the environmental as well as industrial and commercial point of view. In this work, both modification of sodium‐type montmorillonite with 1,2‐dimethyl‐3‐octadecyl‐1H‐imidazol‐3‐ium chloride and additional treatment with [3‐(glycidyloxy)propyl]trimethoxysilane was performed. Thermal stability of the organoclays and nanocomposites prepared by melt compounding was tested by thermogravimetric analysis, differential scanning calorimetry, and melt rheology. In comparison with the organoclays modified with quaternary ammonium compounds, the prepared clays showed substantial suppression of matrix degradation during melt mixing. The increase in interlayer distance of silicate platelets and homogeneity of dispersions in the recycled and virgin PET matrices have been evaluated by transmission electron microscopy and wide‐angle X‐ray scattering. The higher degree of delamination in the nanocomposites filled with imidazole organoclays was in a good agreement with improved rheological characteristics and led to significant enhancement in mechanical properties and thermal stability. A difference in structure (besides the level of delamination and homogeneity of silicate platelets) of recycled versus virgin PET nanocomposites was detected by X‐ray diffraction patterns. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation of novel ZSM‐5 zeolite‐filled chitosan membranes for pervaporation separation of dimethyl carbonate/methanol mixtures
Authors: Liu Bingbing , Cao Yiming , Wang Tonghua , Yuan Quan
Published: July 2007

Novel mixed matrix membranes were prepared by incorporating ZSM‐5 zeolite into chitosan polymer for the pervaporative separation of dimethyl carbonate (DMC) from methanol. These membranes were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray diffraction (XRD) to assess their morphology, intermolecular interactions, and crystallinity. Sorption studies indicated that the degree of swelling for zeolite‐filled membranes increased with zeolite content in the membrane increasing and the separation selectivity of DMC/methanol was dominated by solubility selectivity rather than diffusivity selectivity. The characteristics of these membranes for separating DMC/methanol mixtures were investigated by varying zeolite content, feed composition, and operating temperature. The pervaporation separation index (PSI) showed that 5 wt % of ZSM‐5 zeolite‐filled membrane gave the optimum performance in the PV process. From the temperature‐dependent permeation values, the Arrhenius activation parameters were estimated. The resulting lower activation energy values obtained for zeolite‐filled membranes contribute to the framework of the zeolite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Fluorocarbon‐containing hydrophobically modified poly(acrylic acid) gels as drug release system
Authors: Zhao Xian , Tian Qin , Tang Xiaozhen
Published: July 2007

Hydrophobically modified acrylic acid (AA) hydrogels containing fluorocarbon hydrophobic group and hydrocarbon‐modified gels using 2‐(N‐ethylperfluorooctanesulfoamido) ethyl methacrylate (FMA), and lauryl acrylate (LA) respectively, 2‐(N‐ethylperfluorooctanesulfoamido) ethyl methacrylate (FMA), were synthesized. Acetaminophen, with analgesic and antipyretic property, acted as the model drug. Swelling, rheological, and mechanical properties of the gels were investigated. Fluorocarbon‐modified gels show the stronger hydrophobicity than do the hydrocarbon‐modified gels, which affected the gel's drug‐releasing behavior. The drug release behavior depends on pH of the solution medium, the type of hydrophobic modification and the amount of hydrophobes. Hydrophobically modified PAA gels have higher storage modulus E′ than the unmodified PAA gels. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Effect of percolation on electrical and dielectric properties of acrylonitrile butadiene styrene/graphite composite
Authors: Dahiya H. S. , Kishore Nawal , Mehra R. M.
Published: July 2007

Prelocalized Acrylonitrile Butadiene Styrene/graphite composites were prepared by hot compression molding technique. The increased conductivity with increase of graphite content exhibits percolation phenomenon. The current–voltage characteristics are found to change from nonlinear to linear above the percolation threshold. A positive temperature coefficient of resistance is observed in these composites, and this effect is more pronounced in samples having graphite concentration near percolation threshold. The dielectric constant was found to increase slowly up to the percolation concentration and beyond it a sudden increase in its value is observed. The dissipation factor exhibits maxima in the vicinity of percolation threshold. The dielectric properties are discussed in terms of the interfacial Maxwell‐Wagner effects. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
E‐beam‐cured layered‐silicate and spherical silica epoxy nanocomposites
Authors: Chen Chenggang , Anderson David P.
Published: July 2007

This research demonstrates that an epoxy nanocomposite can be made through electron beam (e‐beam) curing. The nanofillers can be two‐dimensional (layered‐silicate) and zero‐dimensional (spherical silica). Both the spherical silica epoxy nanocomposite and the layered‐silicate epoxy nanocomposite can be cured to a high degree of curing. The transmission electron microscopy (TEM) and small‐angle X‐ray scattering of the e‐beam‐cured layered‐silicate epoxy nanocomposites demonstrate the intercalated nanostructure or combination of exfoliated and intercalated nanostructure. The TEM images show that the spherical silica epoxy nanocomposite has the morphology of homogeneous dispersion of aggregates of silica nanoparticles. The aggregate size is ∼ 100 nm. The dynamic mechanical analysis shows that the storage modulus of the spherical silica nanocomposite has been improved, and the glass transition temperature can be very high (∼ 175°C). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Synthesis of Novel 1‐Pyrazolylpyridin‐2‐ones as Potential Anti‐Inflammatory and Analgesic Agents
Authors: Ismail Magda M. F. , Ammar Yousry A. , El‐Zahaby Heba S. A. , Eisa Sally I. , El‐Sayed Barakat Saber
Published: July 2007

A new series of 4‐alkyl/aryl‐2‐oxo‐1‐pyrazolyl‐1,2‐dihydropyridine‐3‐carbonitriles, pyrazolo[3,4‐b]pyridine‐5‐carbonitriles and pyrido[2,3‐d]pyrimidine‐6‐carbonitriles have been synthesized and tested for their anti‐inflammatory and analgesic activities. Among the tested compounds, 3e and 8b exhibited comparable anti‐inflammatory activity to the standard (indomethacin). Compounds 5, 7a, and 8b displayed potent analgesic activity. Detailed syntheses, spectroscopic and biological data are reported.
Introduction to the special topic section on mining Web resources for enhancing information retrieval
Authors: Lam Wai , Yang Christopher C. , Menczer Filippo
Published: July 2007

The amount of information on the Web has been expanding at an enormous pace. There are a variety of Web documents in different genres, such as news, reports, reviews. Traditionally, the information displayed on Web sites has been static. Recently, there are many Web sites offering content that is dynamically generated and frequently updated. It is also common for Web sites to contain information in different languages since many countries adopt more than one language. Moreover, content may exist in multimedia formats including text, images, video, and audio.
On the critical Richardson number in stably stratified turbulence
Authors: Galperin Boris , Sukoriansky Semion , Anderson Philip S.
Published: July 2007

The critical Richardson number, Ric, is used in studies of stably stratified turbulence as a measure of flow laminarization. The accepted range of Ric is between 0.2 and 1. A growing body of experimental and observational data indicates, however, that turbulence survives for Ri ≫ 1. This result is supported by a new spectral theory of turbulence that accounts for strong anisotropy and waves. The anisotropization results in the enhanced horizontal mixing of both momentum and scalar. Internal wave contribution preserves vertical momentum mixing above its molecular level. In the absence of laminarization, Ric becomes devoid of its conventional meaning. Copyright © 2007 Royal Meteorological Society
Molecular changes associated with teratogen‐induced cyclopia
Authors: Loucks Evyn J. , Schwend Tyler , Ahlgren Sara C.
Published: July 2007

BACKGROUND: Exposure of zebrafish embryos to a number of teratogens results in cyclopia, but little is known about the underlying molecular changes. METHODS: Using zebrafish embryos, we compare the effects cyclopamine, forskolin, and ethanol delivered starting just before gastrulation, on gene expression in early axial tissues and forebrain development. RESULTS: Although all three teratogens suppress gli1 expression, they do so with variable kinetics, suggesting that while suppression of Shh signaling is a common outcome of these three teratogens, it is not a common cause of the cyclopia. Instead, all teratogens studied produce a series of changes in the expression of gsc and six3b present in early axial development, as well as a later suppression of neural crest cell marker dlx3b. Ethanol and forskolin, but not cyclopamine, exposure reduced anterior markers, which most likely contributes to the cyclopic phenotype. CONCLUSIONS: These data suggest that each teratogen exposure leads to a unique set of molecular changes that underlie the single phenotype of cyclopia. Birth Defects Research (Part A), 2007. © 2007 Wiley‐Liss, Inc.
Studies in solid‐phase peptide synthesis: A personal perspective
Authors: Mitchell Alexander R.
Published: July 2007

By the early 1970s it had became apparent that the solid‐phase synthesis of ribonuclease A could not be generalized. Consequently, virtually every aspect of solid‐phase peptide synthesis (SPPS) was reexamined and improved during the decade of the 1970s. The sensitive detection and elimination of possible side reactions (amino acid insertion, Nα‐trifluoroacetylation, Nαϵ‐alkylation) were examined. The quantitation of coupling efficiency in SPPS as a function of chain length was studied. A new and improved support for SPPS, the “PAM‐resin,” was prepared and evaluated. These and many other studies from the Merrifield laboratory and elsewhere increased the general acceptance of SPPS leading to the 1984 Nobel Prize in Chemistry for Bruce Merrifield. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90:215–233, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprintversion. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Prediction of the 3D Structure of FMRF‐amide Neuropeptides Bound to the Mouse MrgC11 GPCR and Experimental Validation
Authors: Heo Jiyoung , Han Sang‐Kyou , Vaidehi Nagarajan , Wendel John , Kekenes‐Huskey Peter , Goddard William A.
Published: July 2007

We report the 3D structure predicted for the mouse MrgC11 (mMrgC11) receptor by using the MembStruk computational protocol, and the predicted binding site for the F‐M‐R‐F‐NH2 neuropeptide together with four singly chirally modified ligands. We predicted that the R‐F‐NH2 part of the tetrapeptide sticks down into the protein between the transmembrane (TM) domains 3, 4, 5, and 6. The Phe (F‐NH2) interacted favorably with Tyr110 (TM3), while the Arg makes salt bridges to Asp161 (TM4) and Asp179 (TM5). We predicted that the Met extends from the binding site, but the terminal Phe residue sticks back into an aromatic/hydrophobic site flanked by Tyr237, Leu238, Leu240, and Tyr256 (TM6), and Trp162 (TM4). We carried out subsequent mutagenesis experiments followed by intracellular calcium‐release assays that demonstrated the dramatic decrease in activity for the Tyr110Ala, Asp161Ala, and Asp179Ala substitutions, which was predicted by our model. These experiments provide strong evidence that our predicted G protein‐coupled receptor (GPCR) structure is sufficiently accurate to identify binding sites for selective ligands. Similar studies were made with the mMrgA1 receptor, which did not bind the R‐F‐NH2 dipeptide; we explain this to be due to the increased hydrophobic character of the binding pocket in mMrgA1.
Two‐dimensional display for multivariate data using all principle components embedding chemical information by regular polygon approach (RPA)
Authors: Barakat Nasser A. Mohamed
Published: July 2007

Regular polygon approach (RPA) is a new methodology proposed in this study to visualize the multivariate data points in two‐dimensional space. The proposed approach is excerpted from the phase diagram which is widely utilized in various fields of science. The proposed approach is considered as a modification of the principal component analysis (PCA) display method. However, in RPA all principal components carrying chemically meaningful information might be fully utilized in the visualization process. The data are displayed in an (n + 1)‐side regular polygon where n is the number of principal components embedding chemical information. The proposed method has been applied on 11 real chemical data sets and some of them could not be visualized successfully by the conventional PCA method. The obtained results have indicated that RPA might be exploited in a case of failure of the conventional PCA technique in displaying the data successfully. Copyright © 2007 John Wiley & Sons, Ltd.
Predictive weighting for cluster ensembles
Authors: Smyth Christine , Coomans Danny
Published: July 2007

An ensemble of regression models predicts by taking a weighted average of the predictions made by individual models. Calculating the weights such that they reflect the accuracy of individual models (post processing the ensemble) has been shown to increase the ensemble's accuracy. However, post processing cluster ensembles has not received as much attention because of the inherent difficulty in assessing the accuracy of an individual cluster model. By enforcing the notion that clusters must be ‘predictable’, this paper suggests a means of implicitly post processing cluster ensembles by drawing analogies with regression post processing techniques. The product of the post processing procedure is an intelligently weighted co‐occurrence matrix. A new technique, similarity‐basedk‐means (SBK), is developed to split this matrix into clusters. The results using three real life datasets underpinned by chemical and biological phenomena show that splitting an intelligently weighted co‐occurrence matrix gives accuracy that approaches supervised classification methods. Copyright © 2007 John Wiley & Sons, Ltd.
AMSE optimal design using generalized estimation for multi‐factor response surfaces
Authors: Fan Shu‐Kai S. , Huang Kuo‐Nan
Published: July 2007

Within the realm of average mean squared error (AMSE), generalized estimation (GE; Kupper and Meydrech1,2) is an attractive alternative to estimate the response surface. GE is based on the criterion that minimizes the variance of the fitted response$(\hat Y({\bf x}))$by weighting the parameter estimates in a restricted parameter space provided that an upper bound can be given. Sometimes, in practice, it is quite difficult to provide such an upper bound. In this paper, we relax the restriction on parameter space and then try to present some useful mathematical properties of GE for the multi‐factor design problem. To obtain a GE‐based optimal design, the average prediction variance (APV) and average squared bias (ASB) are computed to form the AMSE, acting as the performance metric. The comparison between the GE and the least squares estimation (LSE) methods for a two‐factor design problem is made to validate GE's merit under the AMSE criterion. In this particular case, the comparison results show that the GE method, on the whole, outperforms the LSE method. The improvement of the GE method over the LSE method becomes more prominent if the potential bias error is significantly present. Moreover, the comparison report provided in the paper can also serve as a practical guide for response surface methodology (RSM) practitioners to choose an appropriate design point arrangement for the GE and LSE methods that achieve the objective of minimum AMSE. Copyright © 2007 John Wiley & Sons, Ltd.
Evaluation of the multivariate selectivity of multi‐way liquid chromatography methods
Authors: Cantwell Marc T. , Porter Sarah E. G. , Rutan Sarah C.
Published: July 2007

Multivariate figures of merit are used to characterize the sensitivity, selectivity, and precision of multi‐dimensional liquid chromatography (LC) methods. Specifically in this work, we used a multivariate selectivity parameter to characterize the performance of orthogonal LC and two‐dimensional liquid chromatography (2D‐LC) methods with and without diode array detection (DAD), and to aid in the optimization of these new separation approaches. We found that the average selectivity of 47 drug compounds was increased by as much as 58% upon the addition of a second, orthogonal separation. We also found that the selectivity for some individual drug compounds improved by more than a factor of two when DAD detection was used compared to single wavelength detection. In the comprehensive 2D‐LC simulations, using a multi‐channel detector increased the average selectivity of 500 components by 7.3% for a 21 s cycle time. The multivariate selectivity parameter was shown to be useful for determining the information gained when additional dimensions of data are collected on multi‐dimensional instrumentation. Copyright © 2007 John Wiley & Sons, Ltd.
Stable Pentacoordinate Carbocations: Structure and Bonding
Authors: Fernández Israel , Uggerud Einar , Frenking Gernot
Published: July 2007

We report that only elements more electropositive than carbon (Group 13, 14, and Be) form stable symmetrical HnECH3EHn+ structures (E=Group 1, 2, 13, or 14 element) with a planar CH3 group symmetrically bonded to two EHn moieties, in analogy with prototypical SN2 transition structures. Analysis of the bonding situation of these pentacoordinate carbon molecules was studied by means of an energy decomposition analysis (EDA) of the interaction energy. This shows that HnECH3EHn+ molecules can be viewed as being composed of one CH3 group that is σ‐covalently bonded to two EHn groups forming a three‐center, two‐electron bond.
Selektive Abtötung von zellulären Krankheitserregern und Verderbsorganismen: Das ELSTERIL®‐Verfahren
Authors: Heinz V. , Sitzmann W. , Töpfl S.
Published: July 2007

ELSTERIL® ist ein in Deutschland entwickeltes Verfahren zur selektiven Abtötung zellulärer Krankheitserreger und Verderbsorganismen. Das Prinzip der Anwendung gepulster elektrischer Felder wurde bereits in den 50er Jahren des letzten Jahrhunderts erkannt und basiert auf dem dielektrischen Durchbruch der Phospholipid‐Doppelschicht der Membranen biologischer Zellen. Man bezeichnet diesen Zellaufschlussmechanismus auch als Elektropermeabilisierung. Verfahrensparameter zur Festlegung des Abtötungserfolgs sind primär die elektrische Feldstärke (ca. 5 – 50 kV/cm) und der Elektroenergieeintrag (ca. 20 – 200 kJ/kg). Darüber hinaus sind auch die Behandlungstemperatur und der Einfluss der Produktmatrix zu berücksichtigen. Basierend auf semi‐empirischen Überlegungen zum Mechanismus der Elektropermeabilisierung werden hier die Grundlagen zum industriellen Einsatz des ELSTERIL®‐Verfahrens dargestellt. Neben verfahrenstechnischen Fragestellungen, die sich aus dem nicht‐kontinuierlichen Modus des Energieeintrags und der Inhomogenität des elektrischen Feldes ergeben, wird ebenfalls auf die Beherrschung der Elektrodenreaktionen eingegangen.
Möglichkeit der Messung von Geschwindigkeiten in einer präparativen HPLC‐Säule mit Hilfe der Magnet‐Resonanz‐Tomographie
Authors: Laiblin T. , Arlt W. , Kaiser R. , Kirsch R.
Published: July 2007

Geschwindigkeiten in einer 26‐mm‐Glaschromatographiesäule können mithilfe der Magnet‐Resonanz‐Tomographie (MRT) gemessen werden. Für die eingesetzte Säule ergibt sich eine gute Übereinstimmung der gemessenen und der zu erwartenden mittleren Geschwindigkeit. Jedoch ist die vom Hersteller für diese Version der Auswertungssoftware angegebene Genauigkeit von 2 cm/s bei einer Auflösung von 0,02 cm/s für eine stichhaltige pixel‐ bzw. voxelbasierte Bewertung der Messungen nicht ausreichend. Durch ein neues, zum Zeitpunkt der Versuche noch nicht zur Verfügung stehendes Software‐Upgrade kann die Genauigkeit auf 0,1 cm/s verbessert werden.
Entwicklung des Porensystems bei der Pyrolyse und Teilvergasung von Pyrolysaten aus Biomasse im Drehrohrreaktor
Authors: Klose W. , Wiest W. , Gómez A.
Published: July 2007

Ölpalmschalen, das Endokarp der Ölpalmfrüchte, sind ein Teil der Restbiomasse aus der Palmölindustrie. Dieser Rohstoff ist ein geeignetes Ausgangsmaterial für die Aktivkohleherstellung. Untersucht werden die Entstehung des Porensystems während der Pyrolyse von Ölpalmschalen und die Teilvergasung des Pyrolysats mit Wasserdampf im Hinblick auf die Aktivkohleherstellung im indirekt beheizten Drehrohrreaktor.
Präparation und Evaluation neuer Hybrid‐Protonenleiter – Teil 1: Ionische Flüssigkeiten als Modifikator in Nafion®‐Hybridmembranen
Authors: Scheffler Rouven , Huth A. , Hübner G. , Wark M. , Caro J.
Published: July 2007

Ziel der Arbeit ist die Präparation und Evaluation neuer Nafion®‐basierter Hybridmaterialien als Protonen leitende Membran für Brennstoffzellen. Bei möglichst geringer Befeuchtung mit Wasserdampf soll im Temperaturbereich von 120 bis 130 °C eine hohe Protonenleitfähigkeit erreicht werden. Es wurde der Ansatz verfolgt, einer kommerziellen Nafion®‐Dispersion drei verschiedene ionische Flüssigkeiten zuzusetzen, die jeweiligen Gemische zu homogenisieren und durch Foliengießen Nafion®‐basierte Hybridmembranen zu erzeugen. Die Protonenleitfähigkeit der erhaltenen Hybridmembranen wurde durch Impedanzspektroskopie charakterisiert. Obwohl bei Raumtemperatur die Protonenleitfähigkeit der drei ionischen Flüssigkeiten als Einzelstoffe unter derjenigen von Nafion® liegt, ergaben sich für einige Hybridmaterialien Verbesserungen der Protonenleitfähigkeit im höheren Temperaturbereich.
Explosionsgrenzen der Zerfallsreaktion von Gemischen aus Ethylenoxid, Propylenoxid und Stickstoff
Authors: Schröder V. , Baumeier A. , Franzen S. , Büttgen Franz
Published: July 2007

Bei technischen Alkoxylierungsreaktionen mit Ethylenoxid (EO) und Propylenoxid (PO) können – auch ohne den Zutritt von Luft – explosionsfähige (zerfallsfähige) Gasphasen auftreten. Für Explosionsschutzmaßnahmen wurden die Stabilitätsgrenzkonzentrationen in EO/PO/N2‐Gemischen bei Temperaturen von 100 °C bis 200 °C und Drücken von 1,0 bar bis 6,0 bar experimentell bestimmt. Ein Vergleich mit Literaturdaten ergab, dass die Messergebnisse auch für größere Behälter anwendbar sind, wenn Zündquellen mittlerer Energie wirksam werden.
Kinetische Studien und Monte Carlo‐Simulation der radikalischen Ter‐ und Tetrapolymerisation
Authors: Schmidt‐Naake G. , Drache M. , Koppers F.
Published: July 2007

Bei der radikalischen Polymerisation von drei und mehr Monomeren verschiedener Reaktivität können im Polymerisationsverlauf Polymere mit sehr unterschiedlichen Copolymerzusammensetzungen und damit auch Polymereigenschaften entstehen. Zur Beschreibung der umsatzabhängigen Zusammensetzung der Comonomere, der integralen und differentiellen Copolymermischung, der Comonomerumsätze und Sequenzverteilungen der Comonomere wird ein Monte Carlo‐Simulations‐Programm vorgestellt und mit experimentellen Untersuchungen zur Ter‐ und Tetrapolymerisation von Donor‐, Acceptor‐ und Neutralmonomeren in diskontinuierlichen und halbkontinuierlichen Versuchen getestet.
Nutzung eines Zellenmodells mit Platzwechselwahrscheinlichkeit für dreidimensionale Berechnungen der Tracerausbreitung – Anwendungsbeispiel: Geruchsausbreitung in der Atmosphäre
Authors: Roßmann T. , Platzer B.
Published: July 2007

Nachdem mit einer künstlichen Nase die Geruchsausbreitung in einem Windkanal untersucht wurde, stehen hier die Berechnungsmöglichkeiten im Vordergrund. Dabei werden ein Gauß‐Modell sowie numerische Berechnungen mit FLUENT und einem Zellenmodell mit Platzwechselwahrscheinlichkeit (ZEMP), das gegenüber früheren Arbeiten auf den dreidimensionalen Fall erweitert wurde, gegenübergestellt und bewertet. Eine Lösung auf der Basis des Gaußmodells erfordert zwar mit großem Abstand den geringsten Aufwand, der Anwendungsbereich ist aber begrenzt. ZEMP basiert auf der Nutzung von bekannten Geschwindigkeitsprofilen und erreicht damit eine ähnliche Flexibilität wie FLUENT, benötigt jedoch eine viel geringere Rechenzeit.
Mikrowellenunterstützte katalytische Nachverbrennung von n‐Hexan an Hopcalit
Authors: Hartmann I. , Einicke W.‐D.
Published: July 2007

Die katalytische Nachverbrennung ist eine sekundäre Abluftbehandlungsmaßnahme und ein etabliertes Verfahren zur Minderung von Emissionen leichtflüchtiger organischer Luftschadstoffe. Die Unterstützung der Reaktion dieser Verbindungen zu den Zielprodukten der Totaloxidation, CO2 und H2O, durch Zufuhr von Mikrowellenenergie an geeigneten Katalysatoren soll den notwendigen Energiebedarf senken und eine flexiblere Verfahrensgestaltung ermöglichen.
Das Verfahren zur Chitosan‐Gewinnung aus dem baltischen Krebs Gammarus lacustris
Authors: Grigoryeva E. , Mezenova E.
Published: July 2007

Als Alternative zur Chitin/Chitosan‐Gewinnung aus Krabben wurde ein schonendes Verfahren entwickelt, das die Chitin‐Herstellung aus dem baltischen Krebs Gammarus lacustris nach enzymatischem Abbau unter Einwirkung krebseigener Enzyme erlaubt. Die Krebse wurden als Ganzes mit den Innereien zerkleinert und nach Zugabe von Biokonservanten (entweder Milchmolke oder Aloe‐Vera‐Extrakt) inkubiert. Ein Eiweißhydrolysat, Nebenprodukt des Abbaus, ist für die Nutztierhaltung interessant. Optimale Reaktionsbedingungen für den enzymatischen Abbau wurden mit statistischer Versuchsplanung ermittelt. Das aus dem Chitin gewonnene Chitosan ist für die Lebensmittelindustrie aber auch für die Medizin gut geeignet. Analysen zeigten, dass die Krebse ca. 4,5 % Chitosan enthalten, mit Molmassen von 140 000 – 190 000 g/mol und Deacetylierungsgraden von 92,8 – 94,6 %.
Experimentelle Untersuchungen des Phasengleichgewichts des Systems Kohlendioxid/Argon und Literaturauswertung zum System Kohlendioxid/Schwefeldioxid
Authors: Köpke D. , Eggers R.
Published: July 2007

Innerhalb des ADECOS‐Forschungsprojektes, das sich mit der Oxyfuel‐Verbrennung von Stein‐ und Braunkohle beschäftigt, soll auch die CO2‐Abtrennung durch Tieftemperaturverflüssigung untersucht werden. Dafür ist die Kenntnis des Phasengleichgewichts in Abhängigkeit von Temperatur und Druck notwendig. Hierzu wurde das System Argon/Kohlendioxid untersucht und das Phasengleichgewicht mit der Peng‐Robinson‐Zustandsgleichung und der PC‐SAFT‐Gleichung modelliert. Des Weiteren wurden Literaturdaten zum Phasengleichgewicht der Mischung CO2/SO2 ausgewertet und mit der Peng‐Robinson‐Zustandsgleichung modelliert.
Efficacy and safety of neoadjuvant trastuzumab combined with paclitaxel and epirubicin
Authors: Dawood Shaheenah , Gonzalez‐Angulo Ana M. , Peintinger Florentia , Broglio Kristine , Symmans William F. , Kau Shu‐Wan , Islam Rabiul , Hortobagyi Gabriel N. , Buzdar Aman U.
Published: July 2007

BACKGROUND.

A previously published prospective randomized phase 3 trial showed that administration of 24 weeks of primary systemic chemotherapy (PST) with paclitaxel and FEC75 (fluorouracil, epirubicin, cyclophosphamide) concurrently with trastuzumab in patients with HER2‐positive primary breast cancer resulted in a 60% pathologic complete response rate (PCR) with no associated severe cardiac toxicity. The purpose of this study was to review the efficacy and safety of a similar regimen outside the setting of a clinical trial.

METHODS.

Patients with HER2‐positive breast cancer (defined as either immunohistochemical 3+ or fluorescence in situ hybridization‐positive) that had received 24 weeks of neoadjuvant trastuzumab concurrently with taxane and anthracycline‐based chemotherapy between 2004 and 2006 were included in the analysis. PST chemotherapy consisted of paclitaxel (80 mg/m2) weekly for 12 weeks followed by 4 cycles of FEC75 (500 mg/m2, 75 mg/m2, and 500 mg/m2, respectively).

RESULTS.

Forty patients were identified. The median age was 48 years (range, 29–81). In all, 60% of patients had stage III disease and 4 had inflammatory breast cancer. The PCR rate was 55% (95% confidence interval [CI], 38.5%–70.7%). At a median follow‐up of 19 months. 5 patients had a recurrence, of which 4 did not achieve a PCR. No severe cardiac events were observed.

CONCLUSIONS.

Stage II and III HER2‐positive breast cancer patients achieved a high rate of PCR with trastuzumab given concurrently with paclitaxel and FEC75 chemotherapy. No severe cardiac events were observed with the regimen. The data concur with the results of a previously published trial. Cancer 2007. © 2007 American Cancer Society.
Epidermal growth factor ligand/receptor loop and downstream signaling activation pattern in completely resected nonsmall cell lung cancer
Authors: Volante Marco , Saviozzi Silvia , Rapa Ida , Ceppi Paolo , Cappia Susanna , Calogero Raffaele , Novello Silvia , Borasio Piero , Papotti Mauro , Scagliotti Giorgio V.
Published: July 2007

BACKGROUND.

In recent years, molecular insights shed light on the role of the epidermal growth factor receptor (EGFR) in nonsmall cell lung cancer (NSCLC), and new therapeutic agents, such as the EGFR tyrosine kinase inhibitors, were tested successfully, with responsiveness to those agents more likely in those patients with specific EGFR gene alterations. The objective of the current study was to investigate the protein profiles of EGFR, c‐erb‐B2, transforming growth factor α (TGF‐α) (one of the EGFR ligands commonly expressed in NSCLC), and some downstream molecules, potentially to detect a subset of tumors with an activated autocrine loop that is responsible for higher intracellular signaling.

METHODS.

One hundred twelve consecutive patients with resected NSCLC were analyzed by immunohistochemistry for EGFR, the c‐erb‐B2 receptor, TGF‐α, and pivotal molecules downstream from EGFR activation. Statistical correlations between the investigated molecular expression profiles and clinicopathologic data were performed.

RESULTS.

EGFR, c‐erb‐B2, TGF‐α and downstream molecule expression, per se, was not correlated significantly with any clinicopathologic variables, with the exception of a significant correlation between squamous histology and EGFR and between adenocarcinoma and TGF‐α. However, nearly 30% of NSCLCs demonstrated coexpression of both TGF‐α and EGFR, and this molecular status was associated positively with a statistically significant expression of phosphatidylinositol 3 kinase and an inversely with mitogen‐activated protein kinase expression.

CONCLUSIONS.

The presence of a subgroup of NSCLCs with an activated autocrine loop may help to explain the mechanisms that lead to the relative ineffectiveness of the EGFR tyrosine kinase inhibitor and may support new clinical trials to define whether the subgroup of patients with these tumors reasonably may benefit from higher doses of such inhibitors or from the simultaneous inhibition of EGFR downstream signaling targets. Cancer 2007. © 2007 American Cancer Society.
Patterns of treatment in older adults with primary central nervous system lymphoma
Authors: Panageas Katherine S. , Elkin Elena B. , Ben‐Porat Leah , DeAngelis Lisa M. , Abrey Lauren E.
Published: July 2007

BACKGROUND.

The incidence of primary central nervous system lymphoma (PCNSL) has increased in recent decades and is highest in people aged ≥65 years. Radiotherapy (XRT) and systemic chemotherapy (CTX), alone or in combination, are reported to extend survival, but treatment‐related toxicity is a particular concern in the elderly. The objective of the current study was to identify factors associated with the receipt and type of treatment in a population‐based cohort of older PCNSL patients.

METHODS.

Using Surveillance, Epidemiology, and End Results (SEER) cancer registry data linked with Medicare claims, the authors identified PCNSL cases in adults aged ≥65 years who were diagnosed between 1994 and 2002. Initial treatment was defined as XRT alone, CTX alone, combined CTX and XRT, or no treatment, based on Medicare claims in the 6 months after diagnosis. The authors assessed the effects of age, comorbidity, and sociodemographic characteristics on the odds of receiving treatment.

RESULTS.

Of 579 PCNSL patients, 464 (80%) received any treatment. XRT alone was the most common modality (46%), followed by combined therapy (33%) and CTX alone (22%). The type of treatment varied by age (P < .0001). The use of CTX alone or in combination with XRT decreased with increasing age, whereas the use of XRT alone increased with age. In adjusted analysis, younger age (P < .01) was found to be predictive of the receipt of any treatment. The use of CTX decreased with age (P < .0001). The median survival was 7 months (95% confidence interval, 6–8 months); no significant time trends were observed.

CONCLUSIONS.

Although the majority of older PCNSL patients received treatment, most did not receive optimal therapy. Age was found to have the greatest influence on treatment selection. Overall survival in elderly PCNSL patients appears to be poor. Cancer 2007. © 2007 American Cancer Society.
Accelerated partial breast irradiation
Authors: Sauer Rolf , Sautter‐Bihl Marie‐Luise , Budach Wilfried , Feyer Petra , Harms Wolfgang , Souchan Rainer , Wollwiener Diethelm , Kreienberg Rolf , Wenz Frederik
Published: July 2007

BACKGROUND.

Breast‐conserving surgery followed by whole‐breast radiotherapy (WBRT) has become the standard treatment for the majority of patients with early breast cancer. Whereas the indications for systemic adjuvant treatment have continuously expanded, there is a tendency to restrict postoperative radiotherapy to accelerated partial breast irradiation (APBI) instead of WBRT.

METHODS.

The different techniques of APBI are described and their respective advantages or potential drawbacks outlined. Moreover, the results described in the literature are briefly reviewed as a basis for the consensus statements and recommendations of the German Society of Radiation Oncology, the German Society of Senology, and the Working Group for Gynecological Oncology of the German Cancer Society.

RESULTS.

The methods mainly used for APBI are: interstitial radiotherapy with multicatheter technique, intraoperative radiotherapy (IORT) using either electrons produced by linear accelerators or 50 kV x‐rays (Intrabeam), the balloon‐catheter technique (MammoSite), or 3D conformal external beam radiotherapy. These techniques have marked differences in dose distribution and homogeneity. The published range of local recurrence rates varies between 0% to 37%, the median follow‐up from 8 to 72 months.

CONCLUSIONS.

To date, follow‐up times mostly do not yet permit a definite judgment concerning the long‐term effectiveness and side effects of APBI. The relevant societies in Germany support randomized clinical studies comparing APBI with WBRT in a well‐defined subset of low‐risk patients. However, the authors expressly discourage the routine use of APBI outside clinical trials. Until definite results show that APBI neither impairs therapeutic outcome nor cosmetic results, WBRT remains the gold standard in the treatment of early breast cancer. Cancer 2007. © 2007 American Cancer Society.
Low‐molecular weight forms of cyclin E differentiate ovarian carcinoma from cells of mesothelial origin and are associated with poor survival in ovarian carcinoma
Authors: Davidson Ben , Skrede Martina , Silins Ilvars , Shih Ie‐Ming , Trope Claes G. , Flørenes Vivi Ann
Published: July 2007

BACKGROUND.

The authors recently reported on the role of cyclin E in differentiating ovarian/primary peritoneal carcinoma from malignant peritoneal mesothelioma using gene expression arrays. In the current study, they analyzed the expression of low‐molecular weight (LMW) forms of cyclin E in ovarian carcinoma, malignant mesothelioma, and benign reactive effusions.

METHODS.

Cyclin E protein expression was analyzed in 98 effusions (72 ovarian carcinomas, 14 malignant mesotheliomas, and 12 reactive specimens) using immunoblotting. Sixty‐two ovarian carcinoma effusions were studied further for cyclin E expression using immunohistochemistry. The correlations between cyclin E expression in ovarian carcinoma and clinical parameters, including chemotherapy response, were analyzed.

RESULTS.

LMW forms of cyclin E were identified in 54 of 72 ovarian carcinoma effusions (75%) compared with 1 of 14 malignant mesothelioma effusions (7%) and 1 of 12 reactive effusions (8%) (P < .001). Their presence in ovarian carcinoma was associated with a higher percentage of cyclin E‐positive cells (P = .001) and increased staining intensity (P < .001) using immunohistochemistry. The presence of LMW forms of cyclin E was correlated with shorter overall survival (P = .021) and progression‐free survival (P = .020). The presence of a higher percentage of cyclin E‐positive cells using immunohistochemistry was correlated with shorter progression‐free survival (P = .026). No association with chemotherapy response was observed.

CONCLUSIONS.

LMW forms of cyclin E differentiated ovarian carcinoma from benign and malignant mesothelial cells and were associated with increased protein expression using immunohistochemistry. The expression of LMW cyclin E forms was not associated with chemotherapy response, although it may be a marker of aggressive disease in patients with metastatic ovarian carcinoma. Cancer 2007. © 2007 American Cancer Society.