bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular alterations resulting from frameshift mutations in peripheral myelin protein 22: Implications for neuropathy severity
Authors: Johnson J.S. , Roux K.J. , Fletcher B.S. , Fortun J. , Notterpek L.
Published: November 2005

Alterations in peripheral myelin protein 22 (PMP22) expression are associated with a heterogeneous group of hereditary demyelinating peripheral neuropathies. Two mutations at glycine 94, a single guanine insertion or deletion in PMP22, result in different reading frameshifts and, consequently, an extended G94fsX222 or a truncated G94fsX110 protein, respectively. Both of these autosomal dominant mutations alter the second half of PMP22 and yet are linked to clinical phenotypes with distinct severities. The G94fsX222 is associated with hereditary neuropathy with liability to pressure palsies, whereas G94fsX110 causes severe neuropathy diagnosed as Dejerine‐Sottas disease or Charcot‐Marie‐Tooth disease type IA. To investigate the subcellular changes associated with the G94 frameshift mutations, we expressed epitope‐tagged forms in primary rat Schwann cells. Biochemical and immunolabeling studies indicate that, unlike the wild‐type protein, which is targeted for the plasma membrane, frameshift PMP22s are retained in the cell, prior to reaching the medial Golgi compartment. Similar to Wt‐PMP22, both frameshift mutants are targeted for proteasomal degradation and accumulate in detergent‐insoluble, ubiquitin‐containing aggregates upon inhibition of this pathway. The extended frameshift PMP22 shows the ability to form spontaneous aggregates in the absence of proteasome inhibition. On the other hand, Schwann cells expressing the truncated protein proliferate at a significantly higher rate than Schwann cells expressing the wild‐type or the extended PMP22. In summary, these results suggest that a greater potential for PMP22 aggregation is associated with a less severe phenotype, whereas dysregulation of Schwann cell proliferation is linked to severe neuropathy. © 2005 Wiley‐Liss, Inc.
Antioxidant and antiinflammatory activities of xanthorrhizol in hippocampal neurons and primary cultured microglia
Authors: Lim Chol Seung , Jin Da‐Qing , Mok Hyejung , Oh Sang Jin , Lee Jung Uk , Hwang Jae Kwan , Ha Ilho , Han Jung‐Soo
Published: November 2005

Xanthorrhizol, a natural sesquiterpenoid isolated from the rhizome of Curcuma xanthorrhiza Roxb (Zingiberaceae), has antibacterial activities and protective effects against cisplatin‐induced hepatotoxicity. In this study, we investigated the activities of xanthorrhizol as an antioxidant or antiinflammatory agent using neuronal and microglial cells. Xanthorrhizol had potent neuroprotective effects on glutamate‐induced neurotoxicity and reactive oxygen species (ROS) generation in the murine hippocampal HT22 cell line. Also, xanthorrhizol inhibited H2O2‐induced lipid peroxidation in rat brain homogenates. The properties of xanthorrhizol as an antiinflammatory agent were investigated in microglial activation by lipopolysaccharide. It reduced the expression of cyclooxygenase‐2 and the inducible nitric oxide synthase, which consequently resulted in the reduction of nitric oxide. The production of proinflammatory cytokines, such as interleukin‐6 and tumor necrosis factor‐α in activated microglial cells, was reduced by xanthorrhizol. These results suggest that xanthorrhizol could be an effective candidate for the treatment of Alzheimer's disease‐ and other neurological disease‐related ROS and inflammation. © 2005 Wiley‐Liss, Inc.
Toward a psychological and cultural model of downsizing
Authors: Mentzer Marc S.
Published: November 2005

Organizational downsizing is often counterproductive and applied irrespective of past financial performance. The popularity of this tactic leads to the question of whether an executive's propensity to downsize is linked to characteristics such as uncertainty avoidance and risk tolerance, which can be examined at either an individual or societal level. Copyright © 2005 John Wiley & Sons, Ltd.
Cultural diversity recomposition and effectiveness in monoculture work groups
Authors: Hopkins Willie E. , Hopkins Shirley A. , Gross Michael A.
Published: November 2005

In this article, we discuss different types of cultural diversity recomposition that can occur in monoculture work groups. Several direct effect propositions are set forth about the impact of cultural diversity recomposition type on monoculture group effectiveness, as are several moderating effect propositions. We identify potential moderators that have not been explored in prior research and discuss the implications that each has for organizational behavior and practice. We then discuss some implications for future research. We conclude this article with a call for establishing a research agenda that will guide our thinking as we explore this topic in more depth. Copyright © 2005 John Wiley & Sons, Ltd.
Multiplex PCR identification of Listeria monocytogenes isolates from milk and milk‐processing environments
Authors: Zeng Haiyan , Zhang Xiaofeng , Sun Zhen , Fang Weihuan
Published: November 2005

A multiplex PCR procedure based on genes iap (coding for the invasion‐associated 60 kDa protein or p60) and hly (coding for listeriolysin O) of Listeria monocytogenes was to used to investigate the status of its contamination along the major milk‐processing environments. Duplex PCR amplified fragments of the iap gene at about 1.45 kb from all strains of major Listeria spp. tested and a 420 bp fragment of hly from L. monocytogenes reference strains. With triplex PCR, all L. monocytogenes strains exhibited a 420 bp fragment of hly as well as a 700 bp fragment of iap instead of its 1.45kb PCR product. The tentative L. monocytogenes isolates (n = 27) out of 566 samples of milk and milk‐processing environments in the PALCAM agar from cultures of buffered listeria enrichment broth were further subjected to both API and triplex PCR identification. Both methods identified the same 20 isolates as L. monocytogenes. The triplex PCR procedure detected as low as 3.2 × 101 cfu mL−1 of listerial cells even in the presence of L. innocua (108 cfu mL−1). It could detect 1.4 × 102 listerial cells mL−1 directly from milk artificially contaminated with the bacteria. Lower levels of L. monocytogenes cells in milk (1.45 × 101 to 1.45 × 100 cfu mL−1) could be detectable if the inoculated milk samples were cultured for 3–6 h. The bacterium was found not only in raw milk, sewage water and vessel surfaces but also in pasteurized milk. Copyright © 2005 Society of Chemical Industry
Quality of the lipid fraction of Italian biscuits
Authors: Caponio Francesco , Summo Carmine , Delcuratolo Debora , Pasqualone Antonella
Published: November 2005

Although not perceived as fatty foods by consumers, biscuits contain a consistent quantity of lipids. Since they are daily present in the diet, an experimental study was carried out with the aim of evaluating the quality of the lipid fraction of biscuits. Amounts of fat ranging from 75 to 231 g kg−1, mainly constituted by refined vegetable oils and margarine, were present. A high variability in fatty acid composition was found and in some cases high amounts of trans isomers of unsaturated fatty acid were observed. In addition, HPSEC analysis of polar compounds indicated an extensive hydrolytic degradation of triacylglycerols and also a high level of oxidative degradation. The latter, demonstrated by means of the contemporary measure of oxidised triacylglycerols and of triacylglycerol oligopolymers, was comparable to that found in hydrogenated oils and fats. Copyright © 2005 Society of Chemical Industry
Sugar and selected amino acid influences on the structure of pyrazines in microwave heat‐treated formulations
Authors: Coleman William M , Steichen Thomas J
Published: November 2005

The amount and type of selected sugars and selected amino acids have been shown to significantly impact the structure of headspace‐volatile pyrazines produced in aqueous microwave heat‐treated formulations. Selection of sugar and amino acid can dictate the structure, yield and distribution of headspace‐volatile pyrazines. Under the same reaction conditions and sugar to ammonium hydroxide ratios, rhamnose was found to produce more pyrazines than did high‐fructose corn syrup (HFCS). With rhamnose, the yield of pyrazines approached 4500 µg mL−1. Formulations selectively enriched in ethyldimethylpyrazines can be prepared by stepwise substitution of HFCS with rhamnose. Formulations preferably enriched in methyl‐ and dimethyl‐(3‐methylbutyl)‐ as well as methyl‐ and dimethyl‐(2‐methylpropyl)pyrazines were prepared through selective combinations of rhamnose/HFCS and amino acids. Stepwise substitution of HFCS with rhamnose coupled with the use of selected amino acids allowed for the control of the yield, structure and distribution of volatile pyrazines in microwave heat‐treated aqueous formulations. Reaction temperature was also found to significantly influence pyrazine yield and distribution. Statistical modeling of the reaction yields as functions of reaction variables produced surfaces with acceptable modeling coefficients. Mechanisms were postulated to account for the increased yields and selected distributions pyrazines when rhamnose was employed. Copyright © 2005 Society of Chemical Industry
Expression of basic genes involved in tea polyphenol synthesis in relation to accumulation of catechins and total tea polyphenols
Authors: Mamati George Edward , Liang Yuerong , Lu Jianliang
Published: November 2005

Catechins, a group of polyphenolic compounds in the green leaf of tea [Camellia sinensis (L.) O. Kuntze], are major components conferring quality attributes and health benefits on processed tea. Expression patterns of the basic genes related to accumulation of the catechins and total polyphenols at different stages of tea leaf development and their relationship with catechin concentration were investigated by reverse transcriptase polymerase chain reaction and high‐performance liquid chromatographic methods. The results showed that the concentration of total catechins and polyphenols in leaves at different stages of development declined with age of the leaf but changes of the individual catechins varied, with a general decrease in catechin gallate and epigallocatechin gallate and increase in epigallocatechin and epicatechin gallate. Genes of phenylalanine ammonium lyase (PAL), dihydroflavonol reductase (DFR) and three chalcone synthase genes (CHS1, CHS2, CHS3) were highly expressed in bud, first leaf and second leaf but were barely detected in mature leaves. The expression of DFR, a downstream gene in the catechin biosynthesis pathway, was closely related to the concentration of total catechins and polyphenols in various stages of leaf development. Copyright © 2005 Society of Chemical Industry
Influence of growth stage and postharvest storage on ascorbic acid and carotenoid content and visual quality of baby spinach (Spinacia oleracea L.)
Authors: Bergquist Sara ÅM , Gertsson Ulla E , Olsson Marie E
Published: November 2005

To investigate the variations in quality with growth stage and postharvest storage, spinach was sown on three occasions. For each occasion, the spinach was harvested at three growth stages at 6‐day intervals. The second stage corresponded to a growth period used for baby spinach by commercial growers. After harvest, the leaves were stored in polypropylene bags at 2 °C or 10 °C. The highest ascorbic acid content in fresh material was found at stage I. During storage, the ascorbic acid content decreased considerably and the dehydroascorbic acid/vitamin C ratio increased. Storage at 2 °C gave a smaller reduction in ascorbic acid content than storage at 10 °C. Total carotenoid content increased or remained stable during storage. Lutein was the major carotenoid, making up about 39% of the total carotenoid content, followed by violaxanthin, β‐carotene and neoxanthin. Visual quality decreased during storage in most cases, and was correlated to initial ascorbic acid and dry matter contents. The initial AA content might therefore be used as a parameter for predicting the shelf‐life of baby spinach. The results also indicate that by harvesting baby spinach a few days earlier than the current commercial stage of harvest the postharvest visual quality and nutritional quality may be improved. Copyright © 2005 Society of Chemical Industry
Determination of nonsteroidal antiinflammatory drugs in water samples using liquid chromatography coupled with diode‐array detector and mass spectrometry
Authors: Debska Jolanta , Kot‐Wasik Agata , Namiesnik Jacek
Published: November 2005

An analytical method for the determination of trace levels of six different nonsteroidal antiinflammatory drugs (NSAIDs) in water samples has been developed and validated. Environmentally relevant pharmaceuticals were chosen according to human consumption in Poland. Final analysis of the target compounds was performed by RP LC–diode‐array detection–MS, whereas sample preparation included an SPE step. For this SPE step, a number of packing materials, such as LiChrolut RP‐18, calixarene, Strata‐X, BAKERBOND Narc‐2, BAKERBOND Polar Plus, BAKERBOND styrene divinylbenzene‐1, and Discovery DSC‐18, were used, and their respective advantages and disadvantages in this study were discussed. The RP‐18 phase was found to be the most retentive for all analytes. The detection limits for compounds in surface waters were varied from 0.005 for diflunisal to 0.095 μg/L for ibuprofen. The average recoveries of NSAIDs from the surface water samples ranged from 80 up to 103%. RSD value is relatively low (from 4% for fenoprofen up to 8% for ibuprofen). The performance of the method was tested with several environmental water samples.
Surface derivatization of poly(p‐phenylene terephthalamide) fiber designed for novel separation and extraction media
Authors: Abe Akira , Saito Yoshihiro , Imaizumi Motohiro , Ogawa Mitsuhiro , Takeichi Tsutomu , Jinno Kiyokatsu
Published: November 2005

The surface derivatization of poly(p‐phenylene terephthalamide) fiber was studied. The obtained surface‐derivatized filaments were packed into a fused‐silica capillary to evaluate its surface characteristics by using GC. As the stationary phase for GC the surface‐derivatized fibers showed higher retention for alkanes and alkylbenzenes than that with the untreated Kevlar fiber. The improvements on the retention power and the peak shape were observed on the benzyl‐modified fibrous stationary phase. The derivatized fibrous materials were also evaluated as the extraction medium in fiber‐in‐tube SPE, and the effect of the surface modification on the extraction power was compared to the parent fiber. The results indicated that the modified fiber possessed a higher extraction power than the untreated fiber. Based on the facts, the successful modification of the fiber surface was estimated.
High extraction efficiency fiber coated with calix[4] open‐chain crown ether for solid‐phase microextraction of polar aromatic and aliphatic compounds
Authors: Liu Mingming , Zeng Zhaorui , Lei Yun , Li Haibing
Published: November 2005

The calix[4] open‐chain crown ether, 5,11,17,23‐tetra‐tert‐butyl‐25,27‐di(2‐allyloxyethoxyl)‐26,28‐dihydroxycalix[4]arene was synthesized and used for preparation of solid‐phase microextraction (SPME) fibers of enhanced extraction efficiency. The new SPME coating made from calix[4] open‐chain crown ether and hydroxyl‐terminated silicone oil was developed with the aid of vinyltriethoxylsilane as bridge using sol–gel method and cross‐linking technology. The efficiency of the novel fiber in the extraction of polar aromatic and aliphatic compounds, such as phenols, alcohols, and volatile fatty acids, was also investigated. Due to the introduction of the polar open‐chain crown ether in calix[4]arene molecules, the calix[4] open‐chain crown ether fiber showed much better selectivity and sensitivity to these polar compounds in comparison with calix[4]arene fiber. It also had superior extraction efficiency when compared to commercial poly(dimethylsiloxane)–divinylbenzene and polyacrylate fibers. Parts per billion to parts per trillion level detection limits were achieved for most of the analytes through SPME in conjunction with GC and flame ionization detector. The linear ranges were two to four orders of magnitude, and the RSD values were below 7% for all analytes. The novel fiber was applied to determine volatile alcohols and fatty acids in wine samples. The volatile‐free wine prepared in this work was used to assure similar chemical environment for analytes in both calibration solutions and in real wine samples, thus compensating for possible matrix interferences. The established internal standard method using 4‐methyl‐2‐pentanol as internal standard showed satisfactory accuracy and precision.
Novel RPLC stationary phases for lipophilicity measurement: Solvatochromic analysis of retention mechanisms for neutral and basic compounds
Authors: Stella Cinzia , Galland Alexandra , Liu Xiangli , Testa Bernard , Rudaz Serge , Veuthey Jean‐Luc , Carrupt Pierre‐Alain
Published: November 2005

An RPLC was developed to rapidly determine lipophilicity of neutral and basic compounds using three base deactivated RPLC stationary phases particularly designed for the analysis of basic compounds, namely, Supelcosil ABZ+Plus, Discovery RP Amide C16, and Zorbax Extend C18. The work consisted of three sets of experiments. In the first log k w values of neutral compounds were extrapolated using hydroorganic mobile phases at different compositions. Good correlation between log k w and log Poct indicated that the method was appropriate for these supports, without adding a silanol masking agent. In the second set of experiments, isocratic log k values of neutral and basic compounds were measured with three different mobile phases. The best estimation of lipophilicity was obtained for neutral and basic compounds when the secondary interactions were strongly reduced (i. e., when basic compounds were under their neutral form). In the third set of experiments, isocratic retention factors of basic compounds (in their neutral form) were measured with a high‐pH mobile phase, on a chemically stable support (Zorbax Extend C18). Under these chromatographic conditions, correlation between the isocratic retention factors and log Poct (log D 10.5) for basic compounds was similar to that for neutral compounds.
Extraction and analysis of different Cannabis samples by headspace solid‐phase microextraction combined with gas chromatography‐mass spectrometry
Authors: Ilias Yara , Rudaz Serge , Mathieu Patrick , Christen Philippe , Veuthey Jean‐Luc
Published: November 2005

A headspace solid‐phase microextraction combined with GC‐MS method was developed for the extraction and analysis of cannabinoids from Cannabis samples. Different commercially available fibres were evaluated; polydimethylsiloxane 100 μm was selected as the most efficient one. In order to enhance sensitivity and reduce analysis time, the sampling temperature was studied and it showed that extraction should be performed at a high temperature (150°C). In relation with the high lipophilicity of cannabinoids, a relatively long desorption time (3 min) was necessary to ensure a total transfer from the fibre into the injection port of the gas chromatograph. The method was finally applied to the extraction of Swiss marijuana samples from different regions. Data treatment by principal component analysis and hierarchical cluster analysis allowed a discrimination of the different batches.
Absolute enantioselective separation: Optical activity ex machina
Authors: Bielski Roman , Tencer Michal
Published: November 2005

The paper describes methodology of using three independent macroscopic factors affecting molecular orientation to accomplish separation of a racemic mixture without the presence of any other chiral compounds, i. e., absolute enantioselective separation (AES) which is an extension of a concept of applying these factors to absolute asymmetric synthesis. The three factors may be applied simultaneously or, if their effects can be retained, consecutively. The resulting three mutually orthogonal or near orthogonal directors constitute a true chiral influence and their scalar triple product is the measure of the chirality of the system. AES can be executed in a chromatography‐like microfluidic process in the presence of an electric field. It may be carried out on a chemically modified flat surface, a monolithic polymer column made of a mesoporous material, each having imparted directional properties. Separation parameters were estimated for these media and possible implications for the natural homochirality are discussed.
Simultaneous densitometric determination of artemisinin, artemisinic acid and arteannuin‐B in Artemisia annua using reversed‐phase thin layer chromatography
Authors: Bhandari Pamita , Gupta Ajai P. , Singh Bikram , Kaul Vijay K.
Published: November 2005

A rapid and simple RP‐TLC method for simultaneous quantification of pharmacologically important sesquiterpene artemisinin (AM) together with its precursors arteannuin‐B (AB) and artemisinic acid (AA) in the inflorescence part of Artemisia annua plant has been developed. The RP‐TLC of sesquiterpenes was performed on RP‐18 F254 S thin‐layer chromatographic plates by developing in mobile phase, containing 0.2% TFA in water/ACN (35 : 65, v/v). The densitometric determination of AM, AB and AA was carried out after derivatization with anisaldehyde reagent at 426 nm in absorption‐reflectance mode.
Extending the array of crosslinkers suitable for the preparation of polymethacrylate‐based monoliths
Authors: Nordborg Anna , Svec Frantisek , Fréchet Jean M. J. , Irgum Knut
Published: November 2005

The in situ preparation of monolithic capillary columns comprising copolymers of butyl methacrylate with ethylene dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and pentaerythritol tetraacrylate using thermal polymerization within 250 μm ID capillaries and their application for μ‐HPLC separations of proteins has been studied. For all crosslinkers, optimization of the porogenic mixture consisting of 1‐propanol and 1,4‐butanediol yielded monoliths with pore sizes above 1 μm suitable for rapid separations at low back pressure. Very good separations were achieved for a protein mixture consisting of ribonuclease A, cytochrome c, myoglobin, and ovalbumin with all tested columns.
Towards framework for knowledge management implementation
Authors: Shankar Ravi , Gupta Amol
Published: November 2005

The implementation of knowledge management (KM) in an organization involves the integration of knowledge from the domains of strategy, structure, processes, and technology. These domains are generally underpinned—when assimilating roadmaps for holistic KM implementation—with standard KM models in the literature. The pioneering models manifesting the holistic ‘growth’ of knowledge in an organization are generally used to underpin the knowledge‐based segregation of organizational structure. However, some authors take a critical view of such theoretical models, and instead suggest the knowledge process‐based models manifesting the ‘circulation’ of knowledge as being a more practical approach to KM implementation. This paper takes the implementation‐oriented approach further, and modifies and integrates the fundamental aspects of KM advocated in these models resulting in the creation of an integrated KM model that renders a practical framework for the broad knowledge processes across the organization. The essence of the proposed integrated model are the knowledge activities permeating an organization, which are categorized in terms of the cyclic knowledge processes of creation, organization, dissemination, and use of knowledge. These processes traverse the segregated structure of an enterprise.

It is suggested that a modified knowledge‐based segregation of enterprise into individual and group, organization, customer interface, and global enterprise be developed based on the cyclic knowledge processes. Further, based on the proposed integrated model, an implementation framework is outlined manifesting the cyclic circulation of knowledge across the organization. Such a framework can provide a link in the KM roadmaps between the abstract categorizations in KM models and the actual implementations using technologies, organizations, and people. Copyright © 2005 John Wiley & Sons, Ltd.
ICTs and knowledge codification: lessons from front office call centers
Authors: Clergeau Cécile
Published: November 2005

This paper investigates human resources management in call centers. Three case studies of call centers focusing on information exchange show that, even if Information and Communications Technologies (ICTs) result in the displacement of the basis of a firm's core competencies from those that may be attributed to individuals to those which may be attributed to a collective, the employees' strengths, customer pressure, environmental competitive pressure, and the specificity of the service production process all exert influences on the organizations so as to limit or even prevent such a collectivization of knowledge. In order to maintain a dynamic process of knowledge management, human resource managers have to re‐equilibrate the basis of the firm's core competencies. In the following paper, we introduce the concept of re‐equilibrating human resource management. It is through this process that management promotes a harmonious dialogue between tacit knowledge and codified knowledge and succeeds in maintaining a dynamic flexibility in skills. Copyright © 2005 John Wiley & Sons, Ltd.
Managing organisations through a process‐based perspective: its challenges and benefits
Authors: Kiraka Ruth N. , Manning Karen
Published: November 2005

The argument presented in this paper is that a process‐based view is useful for identifying good management practices because of its holistic multidimensional view of organisations. A process‐based view involves identifying both the external and internal factors of the organisation's environment that affect processes. With regard to the external environment two forces driving processes are discussed: (1) processes involve responding to the macro‐ and task‐environment influences; (2) processes focus on stakeholder satisfaction. With respect to the internal environment, the relationship between processes and the internal environment is twofold: (1) processes drive or are driven by the strategy of the organisation; (2) processes determine or should determine organisational structure. The theoretical model developed provides a useful tool for managers to consider in their thinking about and planning for their organisations. Copyright © 2005 John Wiley & Sons, Ltd.
Development of a laser plasma x-ray microscope to observe
live hydrated biological specimens
Authors: Kado M , Daido H , Yamamoto Y , Shinohara K , Richardson M C
Published: November 2005

Investigating the structure and the function of life
object performing advanced life activity becomes important. In
order to investigate the life object, it is necessary to observe
living specimens with high spatial resolution and high temporal
resolution. Since laser plasma x-ray source has high brightness
and short pulse duration, x-ray microscope with the laser plasma
x-ray source makes possible to observe living specimens. Such as
chromosomes, macrophages, bacterium, and so on have been observed
by contact x-ray microscopy. The x-ray images obtained by indirect
measurements such as the contact x-ray microscopy have difficulty
to avoid artificial effect such as irregular due to developing
process. Development of an x-ray microscope with laser plasma
x-ray source is necessary to avoid such defects. We have been
developing an x-ray microscope with laser plasma x-ray source to
observe wet live specimens. The detail of the x-ray microscope
will be presented.
Alloying with copper to reduce metal dusting of nickel
Authors: Zhang J. , Cole D.M.I. , Young D.J.
Published: November 2005

Copper is thought to be noncatalytic to carbon deposition from gas atmospheres, and owing to its extremely low solubility for carbon, inert to the metal dusting reaction. Thus, the addition of copper to nickel, which forms a near perfect solid solution, may be able to suppress or greatly retard the metal dusting of the alloy, without the need for a protective oxide scale on the surface.

The dusting behaviour of Ni‐Cu alloys containing up to 50 wt% Cu, along with pure Cu, was investigated in a 68%CO‐31%H2‐1%H2O gas mixture (aC: 19) at 680°C for up to 150 h. Surface analysis showed that two types of carbon deposits, graphite particle clusters and filaments, were observed on pure Ni and Ni‐Cu alloys with Cu contents of up to 5 wt%. Alloys with more than 10 wt% Cu showed very little coking, forming filaments only. SEM and TEM analyses revealed metal particles encapsulated by graphite shells within the graphite particle clusters, and metal particles at filament tips or embedded along their lengths. A kinetic investigation showed that alloy dusting rates decreased significantly with increasing copper levels up to 10 wt%. At copper concentrations of more than 20 wt%, the rate of metal dusting was negligible. Although pure copper is not catalytic to carbon formation, scattered carbon nanotubes were observed on its surface. The effect of copper on alloy dusting rates is attributed to a dilution effect.
Performance of candidate gas turbine abradeable seal materials in high temperature combustion atmospheres
Authors: Simms N. J. , Norton J. F. , McColvin G.
Published: November 2005

The development of abradeable gas turbine seals for higher temperature duties has been the target of an EU‐funded R&D project, ADSEALS, with the aim of moving towards seals that can withstand surface temperatures as high as ∼ 1100°C for periods of at least 24,000 h. The ADSEALS project has investigated the manufacturing and performance of a number of alternative materials for the traditional honeycomb seal design and novel alternative designs.

This paper reports results from two series of exposure tests carried out to evaluate the oxidation performance of the seal structures in combustion gases and under thermal cycling conditions. These investigations formed one part of the evaluation of seal materials that has been carried out within the ADSEALS project.

The first series of three tests, carried out for screening purposes, exposed candidate abradeable seal materials to a simulated natural gas combustion environment at temperatures within the range 1050–1150°C in controlled atmosphere furnaces for periods of up to ∼ 2,500 h with fifteen thermal cycles. The samples were thermally cycled to room temperature on a weekly basis to enable the progress of the degradation to be monitored by mass change and visual observation, as well as allowing samples to be exchanged at planned intervals. The honeycombs were manufactured from PM2000 and Haynes 214. The backing plates for the seal constructions were manufactured from Haynes 214. Some seals contained fillers or had been surface treated (e.g. aluminised).

The second series of three tests were carried out in a natural gas fired ribbon furnace facility that allowed up to sixty samples of candidate seal structures (including honeycombs, hollow sphere structures and porous ceramics manufactured from an extended range of materials including Aluchrom YHf, PM2Hf, Haynes 230, IN738LC and MarM247) to be exposed simultaneously to a stream of hot combustion gas. In this case the samples were cooled on their rear faces to produce a temperature gradient through the seals and the samples were thermally cycled by switching the natural gas off every three hours. The total exposure period for each test was ∼ 1,000 h, with seal face temperatures of 1000–1180°C.

The performance of the materials in these tests was evaluated using visual observations and cross‐sectional examinations using optical and SEM/EDX techniques. The data gathered have included measurements of oxide thickness and metal‐loss on the exposed samples.

A wide range of materials performances has been observed in these studies from minimal damage through to total destruction of samples. Overall, this study has shown that there is still a lot of development work required in order to move to higher temperature sealing systems structures in gas turbine applications.
The influence of alloying elements on the corrosion behaviour of ferritic steels in simulated combustion atmospheres
Authors: Sroda S. , Baxter D. , Arponen M.
Published: November 2005

The low‐chromium steels (Cr content 0.7–1.4 wt.%) are usually being used in low temperature boiler applications where the environments are not so aggressive as in waste‐fire boilers. To improve their mechanical properties and corrosion resistance several alloying elements have been used. In the present study the new low‐chromium steels modified with Si, Ni and Ce have been investigated. These steels were compared with the common boiler steel – 2.25Cr1M.

The multi‐sample exposure tests were made in moist air (8% O2 + 15% H2O) with and without 200 ppm SO2 or 2000 ppm HCl addition at the isothermal temperature of 500°C. Corrosion products were analysed by Scanning Electron Microscope with Energy Dispersive Spectrometer (SEM/EDS) and XRD techniques. The results of the study show that addition of Ni and Si to the steels studied could improve their corrosion resistance, but only in moist air atmospheres. In SO2‐containing atmospheres the corrosion resistance seems to remain the same, when in HCl‐containing atmospheres Ni and Si additions seem to have a negative effect on the corrosion behaviour. As could by seen from SEM analysis, the scales formed, on the steels with above elements, are more adherent to the metallic core.

The cerium was added to the studied materials mainly to improve their mechanical properties. This alloying element seems to increase the corrosion rate of materials, especially in atmospheres containing Cl.
Molten glass corrosion resistance of new. Mo‐Ru‐Si compounds
Authors: Littner A. , François M. , Tobola J. , Elkaim E. , Malaman B. , Vilasi M.
Published: November 2005

In spite of a very promising potential for a large field of high temperature applications, MoSi2 shows only a limited resistance against molten glass corrosion. Efforts to improve the performance of MoSi2‐based materials led to the investigation of the Mo‐Ru‐Si phase diagram. The isothermal section at 1673 K revealed five new intermetallics with original structures. The crystallographic study of two of them was made using standard and synchrotron X‐ray measurements combined with KKR (Korringa‐Kohn‐Rostoker) calculations. The use of such total energy electronic structure calculations was helpful in order to localize accurately Mo and Ru in the new compound β‐Mo26Ru47Si27. This compound crystallizes in P4/mmm space group with a = 9.2164(1) Å, c = 2.88721(1) Å, Dx = 9.69(1) g/cm3. The structure has been refined by the Rietveld method down to Rp = 1.1%, RB = 12.0 %, RF = 8.7% for 6814 observed data and 271 independent reflections. Moreover, electrochemical techniques enabled the determination of the redox properties of the new intermetallic compounds. It has been shown that, in contact with molten glass at 1623 K, Mo‐Ru‐Si compounds were subjected to electrochemical reactions leading to the simultaneous oxidation of silicon and molybdenum. The progressive superficial depletion of Si and Mo resulted in the more or less rapid formation of a thick, porous and low adherent Ru‐layer. Consequently, the results showed that Ru‐additions had no positive effect on the molten glass corrosion resistance of MoSi2‐based materials. The formation of a porous Ru‐layer should even accelerate the degradation kinetics through galvanic coupling occurring between the superficial layer and the bulk material.
Improving metal dusting resistance of. transition‐metals and Ni‐Cu alloys
Authors: Nishiyama Y. , Moriguchi K. , Otsuka N. , Kudo T.
Published: November 2005

The present study focuses on a new technique for the prevention of metal dusting in carbonaceous gas environments at intermediate temperature. Preliminary laboratory metal dusting test was conducted for transition‐metals and Ni‐x%Cu binary alloys in a simulated 60%CO‐26%H2‐11.5%CO2‐2.5%H2O (in vol.%) gas mixture at 650°C for 100 h. The metal dusting caused no coke deposition on transition‐metals of Cu, Ag, and Pt, while those of Fe, Co, and Ni have a large amount of coke and lost mass. Whether or not coking behavior of Ni‐Cu binary alloys formed any oxide scales in the simulated gas environment depended on the Cu content. Specimens containing low Cu were entirely covered with coke and showed rough metal surfaces due to the degradation of metal. Alloys of 20% and more Cu, on the contrary, had no coke deposition and smooth metal surfaces, suggesting alloys with an adequate Cu do not react with CO in the gas mixture without an oxide scale barrier. Based on these results, we conclude that Cu does not protect by formation of the oxide scale but has a “Surfactant‐Mediated Suppression” against metal dusting. This effect can be explained in terms of atomistic interaction of CO with transition‐metal surfaces by electronic structure analyses. The concept can be also useful for the practical material design of Ni‐Cr base alloy with excellent metal dusting resistance.
Cyclic Ladder Polymers by Polycondensation of Silylated Tetrahydroxy‐tetramethylspirobisindane with 1,4‐Dicyanotetrafluorobenzene
Authors: Kricheldorf Hans R. , Fritsch Detlev , Vakhtangishvili Lali , Schwarz Gert
Published: November 2005

Summary: 5,5′,6,6′‐Tetra(trimethylsiloxy)‐4,4,4,4′‐tetramethyl‐1,1‐spirobisindane was polycondensed with 1,4‐dicyanotetrafluorobenzene under variation of solvent temperature, time, and feed ratio. Under optimized reaction conditions, all products detectable by MALDI‐TOF mass spectrometry (up to masses around 8 000 Da) proved to be cyclic ladder oligomers and polymers. In N‐methylpyrrolidone and dimethylsulfoxide odd‐numbered cycles were formed in addition to the prevailing even‐numbered ones. However, in sulfolane exclusively even‐numbered cycles were obtained (detectable up to masses around 10 000 Da), together with even‐numbered linear chains. Temperatures above 100 °C enhanced the molecular weights by side reactions. With the less reactive cyano‐2,3,5,6‐tetrafluorobenzene (CTB) again cycles were formed, but their content and the conversions were lower. Polycondensation of CTB up to 160 °C and all polycondensations of cyanopentafluorobenzene gave crosslinked products.

Synthesis of cyclic ladder polymers.

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Synthesis of cyclic ladder polymers.
Kinetic Peculiarities of Ethylene Polymerization over Homogeneous Bis(imino)pyridine Fe(II) Catalysts with Different Activators
Authors: Barabanov Artem A. , Bukatov Gennady D. , Zakharov Vladimir A. , Semikolenova Nina V. , Echevskaja Ljudmila G. , Matsko Michail A.
Published: November 2005

Summary: Method of polymerization inhibition by radioactive carbon monoxide (14CO) has been used to determine the number of active centers (CP) and propagation rate constant (kP) for ethylene polymerization with homogeneous complex 2,6‐(2,6‐(Me)2C6H3NCMe)2C5H3NFeCl2 (LFeCl2), activated with methylalumoxane (MAO) or Al(i‐Bu)3. With both activators the rate profile of polymerization was unstable: high activity [0.8 × 103–1.5 × 103 kg PE per (molFe · h · atm) at 35 °C] of the initial period sharply decreases (sevenfold in 10 min). In the beginning of polymerization with the catalysts LFeCl2/MAO and LFeCl2/Al(i‐Bu)3, the CP values were found to be 8 and 41% of total Fe‐complex content in catalysts, respectively, and decreased 1.5–2‐fold in 9 min. As polymerization proceeds, the kP value for LFeCl2/MAO system decreases from 5 × 104 to 1.5 × 104 L · (mol · s)−1 LFeCl2/MAO, and for LFeCl2/Al(i‐Bu)3 system from 2.6 × 104 to 0.82 × 104 L · (mol · s)−1. Data on the effect of polymerization time on polyethylene molar mass distribution are presented. Basing on the obtained results it was suggested that highly reactive, but unstable centers, dominating at short polymerization times, produce low‐molar‐mass polyethylene, while polyethylene with higher molar mass is produced by less active (low kP) and more stable centers.

Data showing change in molar mass distribution of polyethylene with polymerization time.

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Data showing change in molar mass distribution of polyethylene with polymerization time.
A Low Temperature Polycondensation for the Preparation of Highly Fluorinated Poly(arylene ether sulfone)s Containing Crosslinkable Pentafluorostyrene Moieties
Authors: Ding Jianfu , Qi Yinghua , Day Michael , Jiang Jia , Callender Claire L.
Published: November 2005

Summary: The polycondensation of pentafluorophenyl sulfone (PPSO) with hexafluorobisphenol A (6F‐BPA), or a model compound, 4‐phenoxylphenol (POPOH), has been studied in order to find optimized reaction conditions for the preparation of fluorinated poly(arylene ether sulfone)s (FPAESs). It was found that PPSO had a very high reactivity in N,N‐dimethylacetamide (DMAc), allowing the reaction to occur at temperatures as low as 22 °C, even in the absence of any catalyst. This reaction was promoted by the addition of a trace amount of potassium fluoride (KF). Increasing the amount of KF to 1.05 equiv enhanced the conversion and allowed the reaction to be completed in a short time. Under this reaction condition, KF acted as a catalyst to activate the phenol group and also acted as a base to absorb the HF, which was a by‐product of the polycondensation, to produce high molecular weight polymer. The use of calcium hydride (CaH2) instead of KF as a base in this reaction produced a similar effect with a slightly lower reaction rate. Both base systems were also applicable to the reaction of pentafluorostyrene (FSt) with 6F‐BPA. However, a much higher reaction temperature (125 °C) was required due to the low reactivity of FSt. Reacting FSt with an excess of 6F‐BPA produced a mixture of mono‐ and di‐substituted products of FSt with a controllable ratio, which could further react with PPSO to produce a polymer containing crosslinkable FSt moieties both as end‐capping groups and inserting units. This structure allowed the molecular weight of the polymer and the content of FSt to be adjusted independently. Crosslinked films of this polymer demonstrated an excellent processability and performance in waveguide applications, having refractive indices of 1.5061 (TE) and 1.5038 (TM), and a straight waveguide loss of 0.7 dB · cm−1.

Reaction scheme for the preparation of fluorinated poly(arylene ether sulfone)s.

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Reaction scheme for the preparation of fluorinated poly(arylene ether sulfone)s.
Molecular Structure of 113C‐C2H4/C3H6 Copolymers Prepared in the Presence of Half Sandwich Titanium Methyl – B(C6F5)3 Catalysts
Authors: Sessa Irene , Csok Zsolt , Zambelli Adolfo
Published: November 2005

Summary: Copolymers of propylene with 113C‐ethylene (99% isotopic purity) have been prepared in the presence of Cp*Ti(CH3)3 – B(C6F5)3 (I) or CpTi(CH3)3 – B(C6F5)3 (II) (Cp = cyclopentadienyl, Cp* = pentamethylcyclopentadienyl). 13C NMR analysis confirms previous findings that propylene polymerization in the presence of I is highly regioselective and somewhat isoselective, while catalyst II produces regioblock polypropylene. In the presence of II, polymerization is slightly syndioselective and the average size of the primary regioblocks seems larger than that of the secondary ones. Moreover, secondary insertion seems more syndioselective than the primary.

13C NMR spectra of samples I.2 and II.2.

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13C NMR spectra of samples I.2 and II.2.
Cover Picture: Macromol. Chem. Phys. 22/2005
Authors: Spanring Julia , Buchgraber Christian , Ebel Maria F. , Svagera R. , Kern Wolfgang
Published: November 2005

Cover: The cover shows the principles of the photochemical introduction of trialkylsilanes on a polystyrene surface. A polystyrene sample is inserted into the reaction chamber and irradiated with a UV light source under trialkylsilane atmosphere after removing all excess oxygen. Reaction progress is monitored by FT‐IR spectroscopy (see graphs A, B and C), XPS and contact angle measurements. The polystyrene surface becomes more hydrophobic after prolonged irradiation, as the contact angle investigations show. Further details can be found in the Full Paper by J. Spanring, C. Buchgraber, M. F. Ebel, R. Svagera, and W. Kern* on page 2248.
Cover Picture: Macromol. Mater. Eng. 11/2005
Authors: Schmidt Lars E. , Leterrier Yves , Vesin Jean‐Marc , Wilhelm Manfred , Månson Jan‐Anders E.
Published: November 2005

Cover: A novel ultra‐fast photo‐rheological method was developed, with time resolution down to 1 ms and the capability to monitor up to 5 order of magnitude increase in shear modulus. It also enables structural transitions such as gelation and vitrification in UV‐curable polymers to be determined, and was used to analyze the behavior of acrylated hyperbranched polymers. Further details can be found in the article by L. E. Schmidt, Y. Leterrier, J.‐M. Vesin, M. Wilhelm, and J.‐A. E. Månson* on page 1115.
Functional calculus under Kreiss type conditions
Authors: Vitse Pascale
Published: November 2005

It is shown that for an algebraic Banach space operator T , the Kreiss condition, ‖(zI – T )–1‖ ≤ $ {C \over {| z | - 1} } $, |z | > 1, implies the following functional calculus estimate

where deg(T ) is the degree of the minimal polynomial annihilating T . This result extends the known estimates of the powers of T for Kreiss operators on finite dimensional spaces. In the case of a general Kreiss operator, an estimate of the rational calculus is proved:

Similar estimates hold for the polynomial calculus under generalized Kreiss conditions. A link is also established between the sharp constant in the first estimate and the norm of the best solution for a Nevanlinna–Pick type interpolation problem in analytic Besov classes. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Certain classes of potentials for p ‐Laplacian to be non‐degenerate
Authors: Zhang Meirong
Published: November 2005

Given a positive integer n and an exponent 1 ≤ α ≤ ∞. We will find explicitly the optimal bound rn such that if the Lα norm of a potential q (t ) satisfies ‖q ‖ < rn then the n th Dirichlet eigenvalue of the onedimensional p ‐Laplacian with the potential q (t ): (|u ′|p –2 u ′)′ + (λ + q (t )) |u |p –2u = 0 (1 < p < ∞) will be positive. Using these bounds, we will construct, for the Dirichlet, the Neumann, the periodic or the antiperiodic boundary conditions, certain classes of potentials q (t ) so that the p ‐Laplacian with the potential q (t ) is non‐degenerate, which means that the above equation with λ = 0 has only the trivial solution verifying the corresponding boundary condition. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and Self‐Assembly of Amphiphilic Diblock Copolymers using a Fluorescently Labeled N‐Alkoxyamine Initiator
Authors: Tsimelzon Anna , Deamer David , Braslau Rebecca
Published: November 2005

Summary: An initiator for nitroxide mediated ‘living’ free radical polymerization was prepared with a fluorescent tag attached to the initiating alkyl radical terminus. This was used to synthesize amphiphilic poly(acrylic acid)‐block‐polystyrene diblock copolymers, which self assembled in a tetrahydrofuran/buffer solution to form structures that are visible by fluorescence.

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