bluuebunny/crossref_metadata_2025 huggingface dataset:
Perspektiven der Biothermodynamik – I. Thermostatik und Thermodynamik irreversibler Prozesse
Authors: Keller Jürgen U.
Published: May 2008

Die Anwendung von Begriffen und Methoden der Thermodynamik der Gleichgewichte und der Vorgänge auf Systeme und Prozesse der Biotechnologie hat zur Bildung eines neuen Fachgebietes geführt, der Technischen Biothermodynamik. Der vorliegende Artikel soll der erste einer Reihe sein, in der versucht wird, einen Überblick über die Grundlagen und Möglichkeiten zu geben, die dieses Gebiet dem Verfahrensingenieur eröffnet, und dies auch an einzelnen Beispielen zu demonstrieren. Nach einigen einführenden Bemerkungen werden im vorliegenden Artikel die Grundbegriffe und die Hauptsätze der Thermodynamik für fluide Vielstoffsysteme mit inneren Variablen formuliert. Diese Systeme dienen als Modelle für Biofluide und andere Systeme der Biotechnologie. Danach wird der Formalismus der Thermodynamik irreversibler Prozesse an einem elementaren technischen Beispiel erläutert. In den folgenden Teilen sollen Anwendungen der Thermodynamik auf eine Reihe biochemischer und biotechnischer Systeme diskutiert werden, darunter auch biochemische Moleküle, wie sie in biologischen Membranen auftreten, und vor allem Proteine. Die Themen dieser Beiträge werden sein: Adsorption von Proteinen an festen Oberflächen, Hydratisierung, thermische Stabilität und Aggregation von Proteinen, thermodynamische Modelle des Stoffwechsels in Bakterien sowie Bioreaktoren und Fermenter.
Use of non‐mechanical valves at high temperature—A case study
Authors: Geldart D.
Published: May 2008

Non‐mechanical valves are useful devices for controlling the flow of granular solids using only injected. Gas several types of such devices have been described in the literature. In this paper the consequences of using an incorrectly designed L‐valve to move very hot coarse solids from a fluidized bed calciner to a fluidized bed cooler and the steps taken to remedy the situation are described.
Inlet effect on the coal pyrolysis to acetylene in a hydrogen plasma downer reactor
Authors: Cheng Y. , Chen J. Q. , Ding Y. L. , Xiong X. Y. , Jin Y.
Published: May 2008

Coal pyrolysis to acetylene in hydrogen plasma is a clean process for the coal utilization. A gas–solid downer reactor was employed to facilitate the high temperature reactions of coal pyrolysis in milliseconds. The effect of the inlet design on the coal injection was studied using CFD simulations, which were qualitatively compared with the cold model experiments in the prototype of a 2 MW hydrogen plasma reactor. The results revealed that the distribution of the coal particles near the inlet nozzles was significantly influenced by the layout of the flat‐shaped nozzles and the operating conditions. Accordingly the heating efficiency of the particles by the hot gas showed strong dependence on the inlet design. The hot model tests demonstrated that the reactor performance characterized by the concentration of acetylene in the product gas increased from ∼7.6 to 9.6% by optimizing the nozzle design, which indicated the critical role of the nozzle design in the coal pyrolysis process.
Assessment of cleaner process options: A case study from petroleum refining
Authors: Weston Neil , Clift Roland , Basson Lauren , Pouton Andrew , White Neil
Published: May 2008

Assessment of process changes to reduce, recycle or avoid wastes requires attention to systems which are broader than the immediate process; that is, it is necessary to take a life cycle perspective. Definition of the system boundary for such an assessment can be problematic in itself. A real case study is presented to illustrate the problem of assessing clean technologies: possible modifications to an alkylation unit at a UK refinery. The process uses hydrogen fluoride as alkylation catalyst, and generates fluoridic wastes which are hazardous and require treatment both on‐ and off‐site. Possible changes to avoid, reduce or enable partial recycling of the waste are identified, representing different levels of change in the process and therefore requiring assessment with different system boundaries. The different system definitions lead to differences in the ways data must be compiled for quantitative environmental life cycle assessment, and in the range of stakeholders explicitly or implicitly involved in assessing and implementing the changes. The case study demonstrates some of the less familiar challenges introduced by the “pollution prevention” or “clean technology” paradigms of chemical processing.
Statistical modelling of the spouted bed coating process using positron emission particle tracking (PEPT) data
Authors: Seiler C. , Fryer P. J. , Seville J. P. K.
Published: May 2008

Coating of particles larger than about 1 mm can be achieved in a spouted bed, a particle mobilization device in which a strong particle circulation occurs, rapidly upwards in a lean central “spout” region and downwards in a slowly moving annular settled bed. In a spouted bed coater, a spray nozzle is placed at the base of the spout, spraying upwards into a distinct coating zone. The coating formation in a spouted bed is inter alia a function of (i) the particle motion, that is, how often and where particles enter and traverse the coating zone and (ii) the extent of droplet collection by individual particles passing through the coating zone.

The coating model proposed here is based on the statistical history of individual particles, whose projected area governs the collection of spray droplets in the coating zone. Positron emission particle tracking (PEPT) has been used to determine the particle trajectories, the distribution of cycle times and the size and voidage of the spout. Whilst the model is not capable of delivering absolute values of coating mass a priori, it can predict deviations from a mean, which can itself be determined from an overall mass balance.

To validate the model, a spouted bed coating process was studied in which coarse PVC spheres were coated with the hot‐melt coating material polyethylene glycol (PEG) 1500. Coating mass distributions, derived from the weight data of individual particles before and after manual coating removal, compared (for the studied conditions) very well with the predictions of the model.
Evaluation of flow regimes in a semi‐cylindrical spouted bed through statistical, mutual information, spectral and Hurst's analysis
Authors: Oliveira W.P. , Souza C.R.F. , Lim C.J. , Grace J.R.
Published: May 2008

Hydrodynamic studies were conducted in a semi‐cylindrical spouted bed column of diameter 150 mm, height 1000 mm, conical base included angle of 60° and inlet orifice diameter 25 mm. Pressure transducers at several axial positions were used to obtain pressure fluctuation time series with 1.2 and 2.4 mm glass beads at U/Ums from 0.3 to 1.6, and static bed depths from 150 to 600 mm. The conditions covered several flow regimes (fixed bed, incipient spouting, stable spouting, pulsating spouting, slugging, bubble spouting and fluidization). Images of the system dynamics were also acquired through the transparent walls with a digital camera. The data were analyzed via statistical, mutual information theory, spectral and Hurst's Rescaled Range methods to assess the potential of these methods to characterize the spouting quality. The results indicate that these methods have potential for monitoring spouted bed operation.
Experimental characterization of the flow pattern in an annular fluidized bed
Authors: Collin Anne , Wirth Karl‐Ernst , Ströder Michael
Published: May 2008

The annular fluidized bed combines a long solids residence time and a good heat and mass transfer. To experimentally characterize the flow pattern in the system, pressure drop and capacitance probe measurements have been carried out under ambient conditions in two plants of inner diameters of 0.19 and 0.74 m. Depending on the interaction between gas velocity in the central jet and ratio of bubble to central nozzle diameter, the ratio of internal to external solids circulation can be regulated.
Fluid mechanics of liquid–solid fluidization in the centrifugal field
Authors: Margraf Jan , Werther Joachim
Published: May 2008

The flow pattern in the bed and in the freeboard of a liquid–solid fluidized bed operated in the centrifugal field was investigated. Centrifugal accelerations between 20 and 500 times the gravity were acting on the particles. Both the radius‐dependent centrifugal acceleration and the Coriolis force were found to strongly influence the fluid dynamics. A CFD simulation of the liquid flow in absence of particles showed high tangential velocities which were two orders of magnitude higher than the radially oriented fluidizing velocity. Measurements with a 1 m diameter rotor confirmed the calculations and revealed that also the liquid–solid fluidized bed is moving in the tangential direction although with lower speed than the pure liquid. The bed expansion under these conditions can be described by a Richardson–Zaki type correlation.
Entrained‐flow gasifier fuel blending studies at pilot scale
Authors: Cousins A. , McCalden D.J. , Hughes R.W. , Lu D.Y. , Anthony E.J.
Published: May 2008

For the foreseeable future, coal and petroleum‐based materials, such as petroleum Coke, residuals, and high‐sulphur fuel oil, are being adopted as the feedstocks of choice for gasification projects. Of particular interest from a Canadian perspective is Coke generated from the thermal cracking of the oil sands in Western Canada. Oil sand Coke contains high sulphur (5–6%), and also typically has a low volatile content, and lower reactivity than most coals. Experimental runs have recently been conducted on the pilot‐scale entrained‐flow gasifier at CETC‐Ottawa, blending oil sand Coke with sub‐bituminous and lignite coals, to try and enhance the gasification potential of these materials. Blending Genesee sub‐bituminous coal with the delayed oil sands Coke was found to alleviate problems encountered with slag plugging the reactor when running with Genesee coal alone. Blends of Genesee sub‐bituminous and Boundary Dam lignite coals with Coke achieved higher carbon conversions and cold gas efficiencies than runs completed with the Coke by itself. While using CO2 as the conveying gas into the gasifier was not found to significantly affect the conversion obtained, steam addition was found to have a marked effect on CO and H2 concentrations in the syngas.
New investigation in regime transition from bubbling to turbulent fluidization
Authors: Zhu Haiyan , Zhu Jesse
Published: May 2008

The regime transition velocity from bubbling to turbulent fluidization was investigated in a 0.267 m diameter fluidized bed with FCC particles. Different transition velocities and processes are found from the measurements of differential pressure fluctuations and local solids concentration. The measurements of differential pressure fluctuations shows a relatively quicker global regime transition, while the local regime transition obtained from the local solids concentration presents a more gradual process marked by two transition velocities. These transition velocities increase with initial static bed height. For the same initial static bed height, increasing the spacing between two pressure taps leads to lower pressure fluctuations and the appearance of two transition velocities.
An evaluation of the solid hold‐up distribution in a fluidized bed of nanoparticles using radioactive densitometry and fibre optics
Authors: Esmaeili Babak , Chaouki Jamal , Dubois Charles
Published: May 2008

An experimental study was conducted to assess the solid hold‐up distribution in a fluidized bed of zirconia and aluminum nanoparticles. For this purpose, two different techniques, radioactive densitometry and fibre optic measurement, were used. The results showed that while the fluidization of these nanoparticles occurs in the agglomeration state, it performs homogeneously in terms of phase concentration. This matter is important especially when a polymerization reaction should take place uniformly on the surface of nanoparticles, where the monomer is the fluidizing gas. Both techniques presented uniform solid hold‐up distribution over the cross‐section, although the fibre optic method overestimated the overall solid concentration, which was obtained based on bed expansion results. The radioactive densitometry was, however, capable of properly predicting the phase concentration within the bed according to the bed expansion observation. Finally, the effect of bulk density on the fluidization of nanoparticles was discussed by comparing the fluidization of different types of particulate materials.
Mass transfer and reaction performance of the downer and its hydrodynamic explanation
Authors: Fan Chuigang , Bi Xiaotao , Lin Weigang , Song Wenli
Published: May 2008

Catalytic decomposition of ozone was carried out in a 15‐m high, 90‐mm inner diameter downer reactor. Radial distributions of ozone concentration at different axial elevations under different operating conditions were measured. The results were explained from the flow structure experimental data and corresponding signal analysis in time domain and frequency domain. The aggregation status of solid particles, relative movement between the gas and solids, and the dynamic behaviour of clusters were considered to have a joint influence on the mass transfer and reaction process in the downer.
Simulation of autothermal reforming in a staged‐separation membrane reactor for pure hydrogen production
Authors: Li Anwu , Lim C. Jim , Boyd Tony , Grace John R.
Published: May 2008

Steam methane reforming with oxygen input is simulated in staged‐separation membrane reactors. The configuration retains the advantage of regular membrane reactors for achieving super‐equilibrium conversion, but reaction and membrane separation are carried out in two separate units. Equilibrium is assumed in the models given the excess of catalyst. The optimal pure hydrogen yield is obtained with 55% of the total membrane area allocated to the first of two modules. The performance of the process with pure oxygen input is only marginally better than with air. Oxygen must be added in split mode to reach autothermal operation for both reformer modules, and the oxygen input to each module depends on the process conditions. The effects of temperature, steam‐to‐carbon ratio and pressure of the reformer and the area of the membrane modules are investigated for various conditions. Compared with a traditional reformer with an ex situ membrane purifier downstream, the staged reactor is capable of much better pure hydrogen yield for the same autothermal reforming operating conditions.
Sulphation of limestones in a fluidized bed combustor: The relationship between particle attrition and microstructure
Authors: Scala Fabrizio , Montagnaro Fabio , Salatino Piero
Published: May 2008

Sulphation of two limestones in a fluidized bed combustor has been investigated. One limestone (coarse‐grained) was characterized by a significant population of relatively large pores after calcination; the other (fine‐grained) presented a finer and fairly unimodal pore size distribution. Differences in the microstructure were reflected by different thickness of the sulphate shell formed upon sulphation and ultimate calcium conversion degree. Particle attrition/fragmentation were fairly small under moderately bubbling fluidization conditions. Fragmentation upon impact was significant. The fine‐grained limestone, characterized by a thinner sulphate shell, was more susceptible to fragmentation than the other. Particle fragmentation discloses unreacted CaO enabling secondary sulphation of exhausted particles.
Reduction kinetics of a fluidizable nickel–alumina oxygen carrier for chemical‐looping combustion
Authors: Sedor Kelly E. , Hossain Mohammad M. , de Lasa Hugo I.
Published: May 2008

This study investigates the kinetic modelling of oxygen carrier reduction by methane in the combustion reactor of the chemical‐looping combustion process. The species being reduced and the stability of the fluidizable oxygen carrier sample over repeated reduction–oxidation cycles are established using the temperature programmed reduction and oxidation and the pulse chemisorption characterization methods. The power‐law relation, the nucleation and nuclei growth model and the shrinking‐core models are considered to interpret the experimental kinetics of the oxygen carrier reduction. The obtained results show that the nucleation and nuclei growth model best describes the experimental data providing parameters with adequate statistical fitting indicators.
Comparison of outcomes for elderly patients treated with weekly paclitaxel in combination with carboplatin versus the standard 3‐weekly paclitaxel and carboplatin for advanced nonsmall cell lung cancer
Authors: Ramalingam Suresh , Perry Michael C. , La Rocca Renato V. , Rinaldi David , Gable Preston S. , Tester William J. , Belani Chandra P.
Published: May 2008

BACKGROUND.

The purpose of this study was to compare the outcomes between elderly (aged ≥70 years) patients treated with paclitaxel on a weekly basis and with carboplatin (every 4 weeks) versus the standard 3‐weekly regimen of carboplatin and paclitaxel for first‐line therapy of advanced nonsmall cell lung cancer.

METHODS.

Of the 444 patients enrolled, 136 (31%) were aged ≥70 years. Seventy‐two patients were randomized to the weekly schedule (paclitaxel, 100 mg/m2 weekly for 3 of 4 weeks; carboplatin, area under the curve [AUC] = 6 mg/mL·min on Day 1 every 4 weeks), and 64 patients were randomized to the standard schedule (paclitaxel, 225 mg/m2; carboplatin, AUC = 6 mg/mL·min on Day 1 every 21 days). Patients with stable disease or objective response after 4 cycles of therapy were eligible for maintenance therapy with weekly paclitaxel (70 mg/m2, 3 of 4 weeks).

RESULTS.

The response rate for elderly patients was 26% on the weekly regimen and 19% on the standard schedule. The median survival duration for the weekly and the standard schedules was 37 weeks and 31 weeks, respectively. The 1‐year survival rates were similar at 31% and 33%. Grade 3 to 4 anemia was more common on the weekly schedule (16% vs 6%), whereas grade 3 neuropathy was less common (5.5% vs 9.5%). Nausea and emesis were also less frequent on the weekly schedule.

CONCLUSIONS.

Efficacy was similar between the weekly regimen and the standard regimen of carboplatin and paclitaxel for elderly patients with advanced NSCLC and may be advantageous based on its favorable tolerability profile. Cancer 2008. © 2008 American Cancer Society.
Quantitative assessment of glial cells in the human and guinea pig enteric nervous system with an anti‐Sox8/9/10 antibody
Authors: Hoff Sebastian , Zeller Florian , von Weyhern Claus Werner Hann , Wegner Michael , Schemann Michael , Michel Klaus , Rühl Anne
Published: May 2008

Quantitative changes of enteric glia (EGC) have been implicated in gastrointestinal disorders. To facilitate future studies of EGC in human pathology, we aimed to characterize thoroughly glial markers in the human enteric nervous system (ENS) and to compare EGC in man and guinea pig. Whole‐mount preparations of the enteric nerve plexuses from human and guinea pig ileum and colon were labeled with antibodies against S100b, glial fibrillary acidic protein (GFAP), and p75NGFR and the transcription factors Sox8/9/10 and neuronally counterstained. Abundant immunoreactivity (IR) for S100b, GFAP, p75NGFR, and Sox8/9/10 was detected in EGC of all studied regions. Although the cytoplasmatic staining pattern of most markers did not permit glial quantification, the nuclear localization of Sox8/9/10‐IR allowed to identify and count all EGC individually. In both man and guinea pig, myenteric ganglia were larger and contained more EGC and neurons than submucous ganglia. Furthermore, there were more EGC in the human than in the guinea pig myenteric plexus (MP), glial density was consistently higher in the human ENS, and the glia index (glia:neuron ratio) ranged from 1.3 to 1.9 and from 5.9 to 7.0 in the human submucous plexus (SMP) and MP, respectively, whereas, in guinea pig, the glia index was 0.8–1.0 in the SMP and 1.7 in the MP. The glia index was the most robust quantitative descriptor within one species. This is a comprehensive set of quantitative EGC measures in man and guinea pig that provides a basis for pathological assessment of glial proliferation and/or degeneration in the diseased gut. J. Comp. Neurol. 509:356–371, 2008. © 2008 Wiley‐Liss, Inc.
Pd/C‐Catalyzed Cyanation of Aryl Halides in Aqueous PEG
Authors: Chen Gong , Weng Jiang , Zheng Zhanchao , Zhu Xinhai , Cai Yaoyao , Cai Jiwen , Wan Yiqian
Published: May 2008

An environmentally friendly Pd/C–PEG–H2O system was developed for the cyanation of aryl halides under microwave irradiation. A wide range of aryl bromides, iodides, and some activated chlorides were demonstrated to be cyanated smoothly by using nontoxic K4[Fe(CN)6]·3H2O as the cyanide source. There is no phosphorus‐ or nitrogen‐containing ligand or solvent involved. Moreover, this reaction can becarried out without the protection of inert atmosphere. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Optically Active γ‐Hydroxy Sulfone Julia Reagents for the Synthesis of Peptidyl Olefin Peptidomimetics
Authors: Mirilashvili Sima , Chasid‐Rubinstein Naama , Albeck Amnon
Published: May 2008

Peptidyl olefin peptidomimetics serve as biologically active compounds or as intermediates for other peptidyl isosteres. We developed a chemoenzymatic stereoselective approach to optically active γ‐hydroxy sulfones to be assembled into peptidyl olefins by the Julia reaction. Key enzymatic hydrolysis of prochiral diesters to the corresponding hydroxy esters introduces optical activity. The sequence of the subsequent chemical reactions, either protection–hydrolysis–functionalization or functionalization–hydrolysis–protection, determines the absolute stereochemistry of the final sulfone building block.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Fluorinated Johnson Reagent for Transfer‐Trifluoromethylation to Carbon Nucleophiles
Authors: Noritake Shun , Shibata Norio , Nakamura Shuichi , Toru Takeshi , Shiro Motoo
Published: May 2008

A novel reagent, [(oxido)phenyl(trifluoromethyl)‐λ4‐sulfanylidene]dimethylammonium tetrafluoroborate has been developed for the electrophilic trifluoromethylation of carbon nucleophiles. The reagent was designed as a trifluorinated version of a Johnson‐type methyl‐transfer reagent. The firstexample of vinylogous trifluoromethylation of dicyanoalkylidenes is also demonstrated.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Production, characterization, and efficient transfection of highly pure oligodendrocyte precursor cultures from mouse embryonic neural progenitors
Authors: Pedraza Carlos E. , Monk Raymond , Lei Junying , Hao Qi , Macklin Wendy B.
Published: May 2008

Much current knowledge of oligodendrocyte biology, the myelin‐forming cells in the central nervous system, comes from cell culture studies mainly from postnatal rat tissue but mouse cells have been much more difficult to produce in large quantities. We have developed a high yield protocol for production of oligodendrocyte precursor cells from mouse embryonic neural progenitors grown as neurospheres. Neurospheres can be maintained and expanded for long periods in culture in the presence of epidermal growth factor (EGF). When floating neurospheres were plated on substrate‐coated dishes in media supplemented with platelet derived growth factor (PDGF) and basic fibroblast growth factor (bFGF), the spheres attached and generated migrating cells that were predominantly oligodendrocyte‐lineage cells. Furthermore, cells in spheres could be shifted to the oligodendrocyte phenotype prior to plating on substrate, by incubation in suspension with PDGF/bFGF. Single cell suspensions plated after dissociation of either EGF‐treated neurospheres or PDGF/bFGF‐treated oligospheres had the bipolar, elongated morphology characteristic of oligodendrocyte precursor cells. mRNA and protein expression analysis of the cells generated by this method confirmed their oligodendrocyte lineage. Oligodendrocyte precursors generated by this method matured in response to ciliary neurotrophic factor treatment, producing cells with multiple processes and myelin‐like membranes. The most important aspect of this protocol is the ability to generate very high numbers of relatively pure mouse oligodendrocyte progenitor cells, which can be easily transfected. These studies open up many kinds of investigations on transgenic and mutant mouse oligodendrocytes, thereby providing a valuable tool to study oligodendrocyte biology and development. © 2008 Wiley‐Liss, Inc.
The role of PGP9.5 as a tumor suppressor gene in human cancer
Authors: Tokumaru Yutaka , Yamashita Keishi , Kim Myoung Sook , Park Hannah L. , Osada Motonobu , Mori Masaki , Sidransky David
Published: May 2008

PGP9.5 is a controversial molecule from an oncologic point of view. We recently identified frequent methylation of PGP9.5 gene exclusively in primary head and neck squamous cell carcinoma (HNSCC), suggesting that it could be a tumor suppressor gene. On the other hand, PGP9.5 was reported to be overexpressed in a subset of human cancers presumably due to intrinsic oncogenic properties or as a result of transformation. To demonstrate that PGP9.5 possesses tumor suppressive activity, we examined forced expression by stable transfection of PGP9.5 in 4 HNSCC cell lines. Although all 4 cell lines demonstrated reduced log growth rates in culture after transfection, only 2 cell lines with wild type p53 (011, 022) demonstrated decreased growth in soft agar. In 2 cell lines with mutant p53 (013, 019), we observed no altered growth in soft agar and increased sensitivity to UV irradiation. We then tested for and found a high frequency of promoter methylation in a larger panel of primary tumors including HNSCC, esophageal SCC, gastric, lung, prostate and hepatocellular carcinoma. Our data support the notion that PGP9.5 is a tumor suppressor gene that is inactivated by promoter methylation or gene deletion in several types of human cancers. © 2008 Wiley‐Liss, Inc.
Corn yield response to irrigation interval and the resultant savings in water and other overheads
Authors: Dioudis Paschalis S. , Filintas Agathos T. , Papadopoulos Aristotelis H.
Published: May 2008

The aim of this project was to conduct research into the effect of irrigation interval, using drip irrigation, on the depletion of available soil moisture and on corn yield, and the possible savings it might bring about in water, manpower, energy and other overheads. The experiments were carried out between 2000 and 2001 in the plain of Thessaly, central Greece. The experimental field had a complete randomized block design and consisted of three treatments (i.e. irrigation every 2, 5 and 9 days) for four replicates. Daily measurements were taken of the soil moisture content using the time domain reflectrometry (TDR) method and the depletion of available soil moisture was calculated. The amount of water used in each irrigation session was equal to the cumulative evapotranspiration between two successive irrigation sessions as measured using evaporation pan type A.

Results showed that irrigation could be carried out every nine days instead of every two or even five days, thus bringing about substantial savings in the consumption of water. In addition, other overheads such as manpower, energy, etc. could be cut down with no statistically significant difference in crop yield. Copyright © 2008 John Wiley & Sons, Ltd.
Disjoint T‐paths in tough graphs
Authors: Kaiser Tomáš
Published: May 2008

Let G be a graph and T a set of vertices. A T‐path in G is a path that begins and ends in T, and none of its internal vertices are contained in T. We define a T‐path covering to be a union of vertex‐disjoint T‐paths spanning all of T. Concentrating on graphs that are tough (the removal of any nonempty set X of vertices yields at most |X| components), we completely characterize the edges that are contained in some T‐path covering. Our main tool is Mader's ${\cal S}$‐paths theorem. A corollary of our result is that each edge of a k‐regular k‐edge‐connected graph (k ≥ 2) is contained in a T‐path covering. This is, in a sense, a best possible counterpart of the result of Plesník that every edge of a k‐regular (k‐1)‐edge‐connected graph of even order is contained in a 1‐factor. © 2008 Wiley Periodicals, Inc. J Graph Theory 59: 1–10, 2008
Daily performance at work: feeling recovered in the morning as a predictor of day‐level job performance
Authors: Binnewies Carmen , Sonnentag Sabine , Mojza Eva J.
Published: May 2008

This study examined the state of being recovered in the morning (i.e., feeling physically and mentally refreshed) as a predictor of daily job performance and daily compensatory effort at work. Ninety‐nine employees from public service organizations completed a general survey and two daily surveys on pocket computers over the course of one workweek. Hierarchical linear modeling showed that being recovered in the morning was positively related to daily task performance, personal initiative, and organizational citizenship behavior and negatively related to daily compensatory effort at work. Relationships between the state of being recovered and day‐specific job performance were moderated by job control. For persons with a high level of job control, the relationship between being recovered and daily performance was stronger. Copyright © 2008 John Wiley & Sons, Ltd.
Corrosion behaviour of boiler steels, coatings and welds in flue gas environments
Authors: Kalivodová J. , Baxter D. , Schütze M. , Rohr V.
Published: May 2008

In recent years there has been a steadily increasing focus on energy efficiency as a means to reduce the negative impact of human activity on climate, and in particular the effect that industrial emissions have on changes in the climate, specifically global warming. As far as power generation is concerned, emissions can be limited by maximizing energy efficiency while ensuring high levels of plant reliability. This paper reports on materials development work involving coated heat exchange alloys and the effect of welding of the coated alloys, simulating fabrication, on subsequent corrosion performance under laboratory conditions. Samples of the common boiler steels P91 (9% Cr) and HCM12A (12% Cr) were treated by chemical vapour deposition (CVD) in a pack cementation process to produce Al‐rich coatings up to 100 µm thick. The samples were machined to give bevelled edges for welding. Welding was carried out using commonly available alloy 625 filler metal. It was found that sound weldments could readily be produced provided that care was taken to limit the heat input during the welding process. Excessive heat input could lead to cracking, but more importantly to dilution of Al in the coating adjacent to the weldment and in segregation of elements (Mo and Nb) in the weldment itself. Both dilution and segregation effects led to decreased corrosion resistance.
Corrosion of alloys and their diffusion aluminide coatings by KCl:K2SO4 deposits at 650 °C in air
Authors: Vokál V. , Rohr V. , Pomeroy M. J. , Schütze M.
Published: May 2008

P91 ferritic‐martensitic steel, 17Cr–13Ni and alloy 800 austenitic stainless steels and Inconel 617 alloy have been aluminised to form Fe2Al5, (Fe,Ni)Al and Ni2Al3 aluminide coatings. These alloys and their corresponding coatings were subjected to corrosion in air by 50:50 mol/mol K2SO4/KCl deposits at 650 °C for 300 h. With the exception of the Inconel 617 alloy, significant metal losses (>180 µm) were recorded. These losses were planar for P91 alloy but involved internal corrosion for the two austenitic steels. The (Fe,Ni)Al and NiAl coatings on the austenitic steels and the Inconel 617 alloy were significantly corroded via intergranular and internal chloridation–sulphidation–oxidation. In contrast, the Fe2Al5 coating on the P91 alloy coating was virtually unattacked. For the alloys, the relative extents of corrosion damage can be explained in terms of the stability and volatility of metal chlorides formed. For the coatings, STEM/EDS analyses enable clear linkages to be made between the presence and number of Cr‐rich particles on coating grain boundaries and the corrosion damage observed for the coatings.
Oxide scale formation on Al containing Ni–Cr‐based high temperature alloys during application as flame tube material in recirculation oil burners
Authors: Ackermann H. , Teneva‐Kosseva G. , Köhne H. , Lucka K. , Richter S. , Mayer J.
Published: May 2008

The flame tube is an important functional component of burners using the concept of the flame tube stabilised combustion. Under typical combustion conditions the material of the flame tube is exposed to high temperatures (≥900 °C) and to corrosion attack by the combustion gases. Furthermore as the burners are generally operated intermittently, the material suffers from extreme temperature and atmosphere changes. For flame tubes, a lifetime of approximately 8000 h is desired. Predominantly metallic high temperature materials are used. The scope of the present work was to test—under application conditions and for maximum material temperatures exceeding 900 °C—alternative high temperature alloys for use as tube material. The corrosion resistance of the austenitic Ni–Cr‐based alloys (601, 602 CA, 617 and 693) has been investigated in a burner rig at maximum material temperatures of 950 and 1000 °C and with exposure times from 50 to 3000 h. The chromium content of the alloys was between 20 and 30 wt% and that of aluminium between 1 and 3.4 wt%. Metallographic cross‐sections of samples of the alloys were analysed by electron microprobe yielding information about the microstructure and composition of the oxides in the surface zone and variations during exposure time. This study focuses on the observed specific effects of the alloying element aluminium on the development of the oxide scale and on the lifetime of the alloys. At the alloy surface after 500 h exposure time a chromium oxide scale had formed with aluminium oxides underneath predominantly along grain boundaries. For the alloys with the lower aluminium content, the aluminium oxides built up an open network but not a closed layer. For the alloy with the highest aluminium content (alloy 693) after 50 h two different characteristic microstructures at the surface were found. In one case, the grains at the surface were covered with chromium oxide on top and the remaining grain surface was completely enclosed by aluminium oxides. In the other case, the aluminium oxide formed a thin layer directly below the chromium oxide scale. After 500 h exposure time, a significantly thinner chromium oxide scale and massive internal chromium oxides were observed. Catastrophic corrosion, formation of internal oxides and aluminium nitrides started even after 500 h. It will be demonstrated that the early breakdown of alloy 693 is linked to the aluminium oxides which act as a barrier constricting the diffusion of chromium from the alloy matrix towards the surface. Under the conditions of extreme temperature changes given in the burner the aluminium oxide layer on its part did not provide corrosion protection.
Development of thermal sprayed layers for high temperature areas in waste incineration plants
Authors: Bendix D. , Tegeder G. , Crimmann P. , Metschke J. , Faulstich M.
Published: May 2008

Corrosion and wear in the hot gas area of thermal energy plants are severe problems, which often cause premature damage of components. In general, the most components of plants are made of materials, which are not stable under corrosive conditions. For corrosion protection (and also wear protection) and lifetime extension of these components, coatings with more resistant materials are applied. Because of the high concentration of corrosive species and the alternating composition of the atmosphere near to the components, the waste incineration plant is the “worst case” of high temperature corrosion. Nowadays, the most usual coating process to protect pipes in the waste incineration plants is cladding. In the last few years, alternative processes are under investigation because cladding is very cost‐intensive. The specific costs of thermal spraying are much lower than those of cladding. In addition, the coating by thermal spraying reduces the risk of the dilution of substrate and coating material, different materials can be combined (e.g. metal alloys, ceramics) and the thickness of the layer for an acceptable resistance according to corrosion and wear can be drastically reduced. Thermal spraying has the potential to create cost‐efficient coatings to protect components in the critical zones of incineration plants.

Since many years, ATZ Entwicklungszentrum is involved in the development and/or advancement of materials, technologies and applications of thermal spraying for corrosion and/or wear protection in thermal energy plants. The main focuses of the investigations are layers for components in high temperature areas of waste incineration plants. On the basis of the present results, different coatings (metal alloys, ceramics) and different spray technologies (e.g. HVOF, APS) have been tested by different strategies (corrosion tests under laboratory scale, air cooled material probes inside the hot gas area of an incineration plant and coated pipes in operation as part of the superheater of incineration plants). This paper will give an overview about the current results of these corrosion tests, in which the focus are the investigations with material probes. First results showed that with the combination of different thermal sprayed layers a significant corrosion protection can be achieved.
Void formation and filling under alumina scales formed on Fe–20Cr–5Al based alloys and coatings, oxidised at temperatures up to 1200 °C
Authors: Potter D. J. , Al‐Badairy H. , Tatlock G. J. , Bennett M. J.
Published: May 2008

During the oxidation, in laboratory air, of thin foils of Fe–20Cr–5Al based alloys, voids were formed in the substrate beneath the outer protective alumina scale after times varying from 50 h at 900 °C to 10 min at 1200 °C. Once the substrate aluminium level had dropped below a critical value (≤0.5 wt%), it no longer sustained the alumina scale formation and, as a consequence, continuing oxidation resulted in the initiation and development of a Cr‐rich oxide sub‐layer formation. At the lower temperatures, the voids filled with chromia leading to a scallop‐shaped inner layer beneath the alumina scale. In contrast, at higher temperatures, the Cr‐rich sub‐scale layer was continuous. If the Fe–20Cr–5Al based alloys are deposited as coatings, for example as a compliant layer onto a stronger substrate, there is a risk that other elements (such as silicon) from the substrate may diffuse through the coating and influence the subsequent oxidation behaviour of the coating. In order to simulate this, sandwiches of Fe–Cr–Al and a silicon rich substrate were fabricated and tested over a range of oxidation temperatures. It was then found that the silicon did indeed diffuse through the Fe–Cr–Al layer and change the oxidation mechanism. The voids formed under the alumina were now found to contain silicon oxide rather than chromia, but the void filling mechanism also appeared to be different. With chromia filled voids the filling commenced from the alumina scale, with the oxide growing inwards, while the silica rich regions grew outwards into the voids from the substrate. Scanning electron microscopy and EDX analysis were used to follow these changes and those in other more complex situations. Detailed mechanisms for void and chromia sub‐scale formation and development will be discussed in the paper.
Influence of a TiO2 surface treatment on the growth and adhesion of alumina scales on FeCrAl alloys
Authors: Galerie A. , N'Dah E. , Wouters Y. , Roussel‐Dherbey F.
Published: May 2008

Deposits of TiO2 on FeCrAl alloys were obtained by surface TiO2 slurry application or by immersion of samples in tetraisopropylorthotitanate (TIPT) solution followed by air dry which gave the thinnest coatings. Isothermal oxidation of treated samples showed strong modification compared to non‐treated ones, particularly in the temperature range of 850–925 °C where parabolic rate constants rapidly decreased when alloys were TiO2 treated. SEM surface observation, X‐ray diffraction and ruby fluorescence showed that the presence of TiO2 promoted the formation of α‐Al2O3 whereas non‐treated samples exhibited large amounts of transition aluminas. An interesting effect of the rapid change from metastable to stable α‐alumina was a strong increase of scale adhesion, determined by tensile testing, from 300–400 to 2000 J/m2 for scales grown at 850 °C on Aluchrom YHfAl. This was explained not only by the change from outward to mainly inward growth but also by the volume reduction at the transition to alpha transformation.
“Sandglass”‐Shaped Self‐Assembly of Coil–rod–coil Triblock Copolymer Containing Rigid Aniline‐Pentamer
Authors: Huang Lihong , Hu Jun , Lang Le , Zhuang Xiuli , Chen Xuesi , Wei Yen , Jing Xiabin
Published: May 2008

The amphiphilic PEG1 500‐b‐EM AP‐b‐PEG1 500 (EM PAP) triblock copolymer of poly(ethylene glycol) (PEG) and emeraldine aniline‐pentamer (EM AP) in its concentrated solution can self‐assemble into a special shape like “sandglass”, as observed by transmission electron microscopy (TEM), field emission scanning electron microscopy (ESEM) and atomic force microscopy (AFM). This “sandglass”‐shaped assembly is composed of several “rods” aggregated in the middle, with every “rod” being about 8 µm in length and 300 nm in diameter. We conclude that the special “sandglass”‐shaped assembly may come into being because of the inducement effect of the crystallization of EM AP segments, by studying electron diffraction (ED) results and wide‐angle X‐ray diffusion (WAXD) characterization of the EM PAP triblock copolymer.

magnified image
A splitting positive definite mixed element method for second‐order hyperbolic equations
Authors: Zhang Jiansong , Yang Danping
Published: May 2008

In this article, we establish a new mixed finite element procedure, in which the mixed element system is symmetric positive definite, to solve the second‐order hyperbolic equations. The convergence of the mixed element methods with continuous‐ and discrete‐time scheme is proved. And the corresponding error estimates are given. Finally some numerical results are presented. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
Time, temperature, and strain effects on viscoelastic Poisson's ratio of epoxy resins
Authors: Pandini Stefano , Pegoretti Alessandro
Published: May 2008

Poisson's ratio of polymeric materials, although generally assumed as a constant, is known to display a viscoelastic dependence on time, temperature, and strain. This article investigates the phenomenology of this dependence on two crosslinked epoxy systems with different glass transition temperatures. Poisson's ratio measurements are performed by contact extensometers simultaneously measuring the axial and transverse deformations under two different tensile testing conditions: (i) constant deformation rate, in which the effects of strain, strain rate, and temperature are highlighted; (ii) stress relaxation (or constant deformation), where the dependence of Poisson's ratio on time is studied at various strain levels. The viscoelastic Poisson's ratio increases as strain, temperature, and time increases, with trends markedly depending on the materials glass transition. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.
Structural aspects of the intermolecular hydrogen bond strength: H‐bonded complexes of aniline, phenol and pyridine derivatives
Authors: Szatyłowicz Halina
Published: May 2008

This short review is devoted to the description of the effect of the nature and the strength of intermolecular hydrogen bonds on structural properties of H‐bonded complexes of aniline, phenol and pyridine derivatives. Several hundreds of such complexes, playing an important role in organic chemistry and biochemistry, have been identified and described in the literature. In the introductory part, the idea of the H‐bond is discussed in terms of its historical development, followed by presently accepted classification of H‐bonds. Critical review of quantum methods usually used for the calculations of the geometry of H‐bonded complexes and the energies of H‐bonds is then presented. In the second part, the H‐bond‐induced geometrical, hybridization and aromaticity index changes are discussed. All correlations based on quantum calculations are compared with those derived from the available crystal structure data. Although the experimental data are more scattered than the calculated ones, their agreement is impressive. This unequivocally shows the power of the calculation methods developed in recent years. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of the nematode Phasmarhabditis hermaphrodita and of venom from the endoparasitic wasp Pimpla hypochondriaca on survival and food consumption of the pest slug Deroceras reticulatum; implications for novel biocontrol strategies
Authors: Richards Elaine H , DeMarzo Damian , Port Gordon R , Dani M Paulina , Walters Keith FA
Published: May 2008

BACKGROUND: Controlling pests through disruption of biochemical pathways by physiologically active compounds/factors from animals and plants represents an expanding field of research. The authors investigated whether such factors in venom from the wasp Pimpla hypochondriaca (Retzius) can affect the viability and food consumption of the slug Deroceras reticulatum (Müller), and whether they can improve the efficacy of nematode‐induced slug mortality.

RESULTS: Exposure of slugs to 4 mL of water containing 500, 1000 and 5000 Phasmarhabditis hermaphrodita (Schneider) resulted in significant increases in mortality (with hazard ratios of 3.5, 3.9 and 5.8 respectively) and significant reductions in total food consumption and mean food consumption each day for 21 days. Injection of slugs with 4, 8 or 12 µL of P. hypochondriaca venom resulted in significant increases in mortality (with hazard ratios of 3.3, 4.5 and 9.0 respectively) and significant reductions in total food consumption compared with the controls. However, there was no significant effect of venom on the mean food consumption on individual days of the 21 day assay period, although significant reductions occurred for the 8 and 12 µL doses up to day 10. Injecting slugs with 4 µL of venom prior to exposure to 500 nematodes had no synergistic effect on either mortality or food consumption compared with either of the individual treatments.

CONCLUSIONS: Pimpla hypochondriaca venom contains factors capable of killing and reducing food consumption by D. reticulatum. The utilization of these factors as components of integrated pest management strategies is discussed. © Crown copyright 2008. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.
Biofilm growth from wastewater on MWNTs and carbon aerogels
Authors: Dumitru Anca , Morozan Adina , Ghiurea M. , Scott K. , Vulpe S.
Published: May 2008

The improving carbon nanostructure bioactivity related to a specific microorganism community is an important research goal of bionanotechnology. The functionalized CNTs are used to improve the bioaffinity of working electrode in microbial fuel cells and wastewater treatment. Beside CNTs, carbon aerogel is another carbon material with high surface area, high open porosity and controllable morpho‐structural characteristics. In the present work we investigate the biofilm growth from wastewater on functionalized CNTs and carbon aerogels. The biofilm growth on CNTs and carbon aerogel was monitored by optical and scanning electron microscopy. The influence of the bacterial growth phase on carbon electrode was assessed by cyclic voltammetry measurements in wastewater and 0.5 M potassium phosphate buffer solution. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)