bluuebunny/crossref_metadata_2025 huggingface dataset:
Phonological decoding involves left posterior fusiform gyrus
Authors: Dietz Nicole A.E. , Jones Karen M. , Gareau Lynn , Zeffiro Thomas A. , Eden Guinevere F.
Published: June 2005

Aloud reading of novel words is achieved by phonological decoding, a process in which grapheme‐to‐phoneme conversion rules are applied to “sound out” a word's spoken representation. Numerous brain imaging studies have examined the neural bases of phonological decoding by contrasting pseudoword (pronounceable nonwords) to real word reading. However, only a few investigations have examined pseudoword reading under both aloud and silent conditions, task parameters that are likely to significantly alter the functional anatomy of phonological decoding. Subjects participated in an fMRI study of aloud pseudoword, aloud real word, silent pseudoword, and silent real word reading. Using this two‐by‐two design, we examined effects of word‐type (real words vs. pseudowords) and response‐modality (silent vs. aloud) and their interactions. We found 1) four regions to be invariantly active across the four reading conditions: the anterior aspect of the left precentral gyrus (Brodmann's Area (BA) 6), and three areas within the left ventral occipitotemporal cortex; 2) a main effect of word‐type (pseudowords > words) in left inferior frontal gyrus and left intraparietal sulcus; 3) a main effect of response‐modality (aloud > silent) that included bilateral motor, auditory, and extrastriate cortex; and 4) a single left hemisphere extrastriate region showing a word‐type by response‐modality interaction effect. This region, within the posterior fusiform cortex at BA 19, was uniquely modulated by varying phonological processing demands. This result suggests that when reading, word forms are subject to phonological analysis at the point they are first recognized as alphabetic stimuli and BA 19 is involved in processing the phonological properties of words. Hum Brain Mapp, 2005. © 2005 Wiley‐Liss, Inc.
Semiparametric estimation of lifetime equivalence scales
Authors: Pendakur Krishna
Published: June 2005

Pashardes (1991) and Bankset al.(1994) use parametric methods to estimate lifetime equivalence scales. Their approaches put parametric restrictions on the differences in within‐period expenditure needs across household types, the intertemporal allocation of expenditure, and the shapes of commodity demand equations. This paper puts parametric structure only on the differences in within‐period expenditure needs across household types. This implies structure on the intertemporal allocation of expenditure, but leaves the shapes of commodity demand equations unrestricted. Semiparametric methods are used to estimate within‐period and lifetime equivalence scales with Canadian expenditure data, and to test the restrictions imposed on within‐period expenditure functions. Estimated lifetime equivalence scales are similar in size to those estimated by Bankset al.(1994) and exhibit equal lifetime costs for first and second children. Copyright © 2005 John Wiley & Sons, Ltd.
Effects of soluble metals on human peri‐implant cells
Authors: Hallab Nadim James , Anderson Shelley , Caicedo Marco , Brasher Amee , Mikecz Katalin , Jacobs Joshua J.
Published: June 2005

Despite reports associating tissue necrosis with implant failure, the degree to which processes, such as metal toxicity, negatively impact implant performance is unknown. We evaluated representative human peri‐implant cells (i.e., osteoblasts, fibroblasts, and lymphocytes) when challenged by Al+3, Co+2, Cr+3, Fe+3, Mo+5, Ni+2, and V+3 chloride solutions (and Na+2 as a control) over a wide range of concentrations (0.01–10.0 mM). Cell responses were measured using proliferation assays, viability assays, and microscopic cell morphology assessments. Differential effects were found to be less a function of the cell type than of the composition and concentration of metal challenge. No preferential immunosuppression was demonstrated. Below 0.01 mM, no metal was toxic. The most toxic metals (i.e., Co, Ni, and V) reduced proliferation (IC50), and viability (LC50) and cell morphology of osteoblasts, fibroblasts, and lymphocytes by <50% at challenge concentrations <1 mM. All other metals tested required >5 mM to exact the same responses. Below 1 mM, these toxic metals also induced alterations in all cell morphology consisting of loss of filopodia or lamellipodia or changes in cell shape. Metals that were toxic at clinically relevant concentrations (less than previously reported values in peri‐implant tissues/fluids) include Co (0.6 mM), Ni (0.8 mM), V (0.5 mM) for lymphocytes and Co (0.8 mM), V (0.3 mM), Al (1–5 mM), Fe (1–5 mM) for fibroblasts, and Co (0.8 mM), Ni (0.7 mM), V (0.1 mM) for osteoblasts. Only Co and V were toxic in vitro at concentrations below that detected in vivo in synovial fluid (V at 0.1 mM and Co at 0.8 mM for fibroblasts, and V at 0.4 mM and Co at 0.8 mM on osteoblasts). Thus, soluble Co and V released from Co‐ and Ti‐based alloys, respectively, could be implicated as the most likely to mediate cell toxicity in the periprosthetic milieu. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Cycle‐cocycle partitions and faithful cycle covers for locally finite graphs
Authors: Bruhn Henning , Diestel Reinhard , Stein Maya
Published: June 2005

By a result of Gallai, every finite graph G has a vertex partition into two parts each inducing an element of its cycle space. This fails for infinite graphs if, as usual, the cycle space is defined as the span of the edge sets of finite cycles in G. However, we show that, for the adaptation of the cycle space to infinite graphs recently introduced by Diestel and Kühn (which involves infinite cycles as well as finite ones), Gallai's theorem extends to locally finite graphs. Using similar techniques, we show that if Seymour's faithful cycle cover conjecture is true for finite graphs then it also holds for locally finite graphs when infinite cyles are allowed in the cover, but not otherwise. We also consider extensions to graphs with infinite degrees. © 2005 Wiley Periodicals, Inc. J Graph Theory
Organic mass spectrometry in archaeology: evidence for Brassicaceae seed oil in Egyptian ceramic lamps
Authors: Colombini Maria Perla , Modugno Francesca , Ribechini Erika
Published: June 2005

An analytical procedure based on alkaline hydrolysis and silylation followed by GC/MS analysis was employed to study the formation of characteristic acidic compounds and the development of a distinctive chromatographic pattern in the course of accelerated ageing tests on Brassicaceae seed oil. On the basis of mass spectra of trimethylsilyl derivatives, the main degradation products were identified as α,ω‐dicarboxylic, ω‐hydroxycarboxylic and dihydroxycarboxylic acids, including 11,12‐dihydroxyeicosanoic acid and 13,14‐dihydroxydocosanoic acid. The mass spectra of both these compounds are characterised by fragment ions arising from the α cleavage of the bond between the two vicinal trimethylsiloxy groups, resulting in fragments at m/z 215 and 345 for 11,12‐dihydroxyeicosanoic acid, and at m/z 215 and 373 for 13,14‐dihydroxydocosanoic acid. Other significant fragment ion‐radicals from rearrangement process at m/z [M − 90]+•, [M − 142]+•, 204 as well as fragment ions at m/z [M − 15]+, [M − 105]+, 217 are present in the mass spectra of both the compounds. The results obtained for reference materials were compared with those relating to archaeological organic materials recovered in Egyptian pottery lamps. The occurrence of the same characteristic degradation products found in the reference materials subjected to accelerated ageing indicates an unambiguous origin for the organic archaeological remains and represents the chemical evidence for the use of oil from seeds of Brassicaceae as illuminant. Copyright © 2005 John Wiley & Sons, Ltd.
Chromophore effect in photodissociation at 266 nm of protonated peptides generated by matrix‐assisted laser desorption ionization (MALDI)
Authors: Oh Joo Yeon , Moon Jeong Hee , Kim Myung Soo
Published: June 2005

Chromophore effect in the photodissociation of protonated peptides at 266 nm was investigated using synthetic peptides with the sequence RGGXGGGGGR where X was a phenylalanyl(F), tyrosyl(Y), cysteinyl(C), glycyl(G), seryl(S), or histidyl(H) residue. The peptides with an F or Y residue dissociated efficiently. Fragment ions due to cleavages at either end of the chromophore were especially prominent just as for the peptide with a tryptophanyl residue reported previously.1Photodissociation was observed even for the peptides without any noticeable chromophore at 266 nm. Here, dissociation at all the peptide bonds was almost equally prominent. Photodissociation of the protonated angiotensin I was investigated using the spectral correlation rules observed in the model systems. Role of the chromophores and the plausible mechanisms involved are discussed. Copyright © 2005 John Wiley & Sons, Ltd.
Determination of binding sites in carboplatin‐bound cytochrome c using electrospray ionization mass spectrometry and tandem mass spectrometry
Authors: Yang Gaosheng , Miao Ren , Jin Chen , Mei Yuhua , Tang Huiwei , Hong Jin , Guo Zijian , Zhu Longgen
Published: June 2005

Interaction of carboplatin with cytochrome c (Cyt. c) has been investigated by electrospray ionization mass spectrometry (ESI‐MS) and tandem mass spectrometry (MS/MS). ESI‐MS studies revealed that the ring‐opened adducts of carboplatin with Cyt. c were formed in the stoichiometric ratio of 1 : 1 and 2 : 1 at pH 5.0 and 37 °C and in the stoichiometric ratio of 1 : 1 only at pH 7.0 and 37 °C. It was also found that Cyt. c could be cleaved by carboplatin at pH 2.5 and 50 °C. The cleaved fragments of Cyt. c were determined by ESI‐MS and MS/MS analysis to be Glu66∼Met80, Ac‐Gly01∼Met65, Glu66∼Glu104, Ac‐Gly01∼Met80 and Ile81∼Glu104. The carboplatin prefers to anchor to Met65 first, then to Met80. To further confirm the binding site of Met, AcMet‐Gly was used as the model molecule to investigate its interaction with carboplatin and its hydrolysis reaction. On the basis of species detected during the reaction monitored by ESI‐MS, a possible pathway of the cleavage reaction was proposed. Copyright © 2005 John Wiley & Sons, Ltd.
Hybrid triple quadrupole‐linear ion trap mass spectrometry in fragmentation mechanism studies: application to structure elucidation of buspirone and one of its metabolites
Authors: Zhang Mei‐Yi , Pace Nadia , Kerns Edward H. , Kleintop Teresa , Kagan Natasha , Sakuma Takeo
Published: June 2005

The use of a hybrid triple quadrupole‐linear ion trap (QqQLIT) mass spectrometer system for a comprehensive study of fragmentation mechanisms is described. The anxiolytic drug, buspirone, was chosen as a model compound for this study. With the advent of a QqQLIT instrument, both the traditional quadrupole and the new linear ion trap scans (LIT) could be performed in a single LC run. In the past, a sample had to be run on two different instruments, namely, a triple quadrupole instrument (QqQ) and a 3D ion trap (3D IT) to obtain similar information. With the new QqQLIT technology, collision‐induced dissociation (CID) occur in a quadrupole collision cell, q2, and fragment ions are trapped and analyzed in Q3 operated in LIT mode. In this work, high‐sensitivity product ion spectra of buspirone were obtained from the one‐stage ‘Enhanced Product Ion’ scan (EPI) with rich product ions and no low mass cut‐off. Furthermore, detailed fragmentation pathways were elucidated by further dissociation of each of the fragment ions in the EPI spectrum using MS3 mode in the same run. The MS3 scan was performed by incorporating CID in q2, and trapping, cooling, isolation, and resonance‐excitation in Q3 when operating in LIT mode. This approach allowed unambiguous assignment of all fragment ions quickly with fewer experiments and easier interpretation than the previous approach. The overall sensitivity for obtaining complete fragment ion data was significantly improved for QqQLIT as compared with that of QqQ and 3D IT mass spectrometers. This is beneficial for structure determination of unknown trace components. The method allowed structure determination of metabolites of buspirone in rat microsomes at 1 µM concentration, which was a 10‐fold lower concentration than was needed for QqQ or 3D IT instruments. The QqQLIT instrument provided a simple, rapid, sensitive and powerful approach for structure elucidation of trace components. Copyright © 2005 John Wiley & Sons, Ltd.
Hydrolysis rates of inorganic polyphosphates in aqueous solution as well as in soils and effects on P availability
Authors: Torres‐Dorante Luis O. , Claassen Norbert , Steingrobe Bernd , Olfs Hans‐Werner
Published: June 2005

Applications of polyphosphate‐based fertilizers have been reported to have a positive impact on crop yields as compared to orthophosphate sources. Since plants take up P mainly as orthophosphate, hydrolysis rates of polyphosphates into orthophosphates will determine their fertilizer ability. Laboratory and soil incubation experiments were performed to evaluate hydrolysis rates of pyrophosphate (PP), tripolyphosphate (TP), and trimetaphosphate (TMP) in water as well as in two soils having different P‐fixing capacities. P availability was characterized by measuring the orthophosphate (ortho‐P) and polyphosphate (poly‐P) concentration in soil solution as well as the calcium‐acetate‐lactate (CAL)‐extractable amounts of both forms.

In water, PP was completely hydrolyzed within 15 d, whereas TMP was hydrolyzed only to about 30% after 90 d. In the two soils, polyphosphates hydrolyzed during the incubation period increasing ortho‐P concentration in soil solution as well as in CAL extract. At the end of the incubation, no significant differences in ortho‐P concentration in soil solution and CAL extract were found in the sandy soil, whereas in the silty‐loam soil, polyphosphate applications resulted in higher soil‐solution ortho‐P concentration. Although polyphosphate hydrolysis is mainly affected by the soil‐specific enzymatic activity, it seems that polyphosphates and/or hydrolysis products are preferentially adsorbed/precipitated compared to ortho‐P in the silty loam, thereby influencing the P availability from polyphosphate sources.
Spatial variability of sequentially extracted P fractions in a silty loam
Authors: Heilmann Elena , Leinweber Peter , Ollesch Gregor , Meißner Ralph
Published: June 2005

Knowledge of the spatial distribution of soil P forms in agricultural fields is important for evaluating the risk of P transfer to waterways. The objective of this study was to characterize the spatial variation of total P (Pt) and sequentially extracted P forms in the Ap horizon of arable soils at the field scale. Soil samples were taken on a regular grid of 50 m × 50 m with 40 sampling points. Chemical analyses included basic soil properties, Pt, sequentially extracted P forms, and acid phosphomonoesterase activity. The spatial variability was analyzed by geostatistics and descriptive statistics. The concentrations of Pt ranged from 521 to 1020 mg kg–1 with lower values observed for Gleysols and Stagnic Phaeozems and higher values for Luvisols and Cambisols. For the sequentially extracted P fractions, the largest coefficients of variation (c.v.) were found for NaHCO3‐Po (41%), NaHCO3‐Pi (36%), NaOH‐Po (34%), and resin‐P (33%). Despite this great spatial variability, no spatial dependence could be proved by geostatistics because the calculated range of P forms (<10 m) was below the smallest sampling distance (50 m). A clear trend of increasing concentrations and proportions of organic NaHCO3‐ and NaOH‐P fractions and phosphomonoesterase activity towards lower slope positions and the discharging brook indicated that Gleysols were a particular source of P losses to waterways in this catchment. It was concluded that these soils require a specific management with reduced P inputs and, perhaps, chemical treatment to fix leachable P.
Proportions of subsurface drainages in large areas—methodological study in the Middle Mulde catchment (Germany)
Authors: Hirt Ulrike , Meyer Burghard C. , Hammann Torsten
Published: June 2005

High nitrogen (N) input to rivers requires measures for the reduction of diffuse N pollution. Beside the groundwater, artificial subsurface drainage systems are the main pathways of diffuse N input into rivers. Nevertheless, the N discharge via subsurface drainage systems is one of the main missing links for modeling, especially because of the lack of data bases of subsurface drainage areas. We introduce a method to calculate the normally unknown proportions of drained areas in arable lands improving the existing method by Behrendt et al. (2000). The method is applied for the catchment of Middle Mulde river (area: 2,700 km2) in Saxony/Germany. The data records of the mesoscale soil mapping are allocated to the subsurface‐drainage areas digitalized in representative areas using ARC/INFO GIS. In this way, it is possible to establish a differentiated record of the proportion of subsurface‐drainage area of each regional site type. The results were extrapolated to the entire area by transferring the proportions of subsurface‐drainage areas to areas where no information on drainage areas was available. The approach is well‐suited for future model approaches on a regional scale. By creating and integrating new data sets derived from modern GIS operations, the approach reduces the uncertainty of modeling N and water fluxes.
Sorption of HOC in soils with carbonaceous contamination: Influence of organic‐matter composition
Authors: Abelmann Kerstin , Kleineidam Sybille , Knicker Heike , Grathwohl Peter , Kögel‐Knabner Ingrid
Published: June 2005

Detailed information about structure and composition of organic sorbents is required to understand their impact on sorption capacity and sorption kinetic of organic pollutants. Therefore, the chemical composition of organic material from 18 geosorbents was investigated by solid‐state 13C nuclear‐magnetic‐resonance (NMR) spectroscopy. Structural parameters such as aromaticity, polarity, and alkyl‐C content were related to the Freundlich sorption exponent (1/n) and the sorption coefficient $ K_{OC}^\circ $. The geosorbents included three natural and four combusted coals (carbonaceous material), three Histosols, five mineral soils from Germany containing inputs of technogenic carbonaceous material, derived from industrial activities, and four non‐contaminated mineral soils from Germany. Equilibrium sorption was measured for five hydrophobic organic compounds and analyzed with the solubility‐normalized Freundlich sorption isotherm. With increasing maturation degree, the proportion of polar constituents decreases from the natural soils to the coals. In contrast to the non‐polluted mineral soils, the soils with technogenic input are characterized by high aromaticity and low polarity. A positive correlation between sorption coefficient $ K_{OC}^\circ $ and aromaticity was found. The Freundlich exponent (1/n) is negatively correlated with the aromaticity, denoting an increase of adsorption processes with increasing aromaticity. Likewise, the contribution of partitioning decreases. This sorption mechanism predominates only if the organic matter in the samples contains a high proportion of polar compounds.
DOC leaching from a coniferous forest floor: modeling a manipulation experiment
Authors: Tipping Edward , Fröberg Mats , Berggren Dan , Mulder Jan , Bergkvist Bo
Published: June 2005

The DyDOC model simulates the C dynamics of forest soils, including the production and transport of dissolved organic matter (DOM), on the basis of soil hydrology, metabolic processes, and sorption reactions. The model recognizes three main pools of soil C: litter, substrate (an intermediate transformation product), and humic substances. The model was used to simulate the behavior of C in the O horizon of soil under a Norway spruce stand at Asa, Sweden, that had been subjected to experimental manipulations (addition and removal) of above‐ground litter inputs and to removal of the Oi and Oe layers. Initially, the model was calibrated using results for the control plots and was able to reproduce the observed total soil C pool and 14C content, DOC flux and DO14C content, and the pool of litter C, together with the assumed content of C in humic substances (20% of the total soil C), and the assumed distribution of DOC between hydrophilic and hydrophobic fractions. The constant describing DOC exchange between micro‐ and macropores was estimated from short‐term variations in DOC concentration. When the calibrated model was used to predict the effects of litter and soil manipulations, it underestimated the additional DOC export (up to 33%) caused by litter addition, and underestimated the 22% reduction in DOC export caused by litter withdrawal. Therefore, an additional metabolic process, the direct conversion of litter to DOC, was added to the model. The addition of this process permitted reasonably accurate simulation of the results of the manipulation experiments, without affecting the goodness‐of‐fit in the model calibration. The results suggest that, under normal conditions, DOC exported from the Asa forest floor is a mixture of compounds derived from soil C pools with a range of residence times. Approximately equal amounts come from the litter pool (turnover time 4.6 yr), the substrate pool (26 yr), and the humic‐substances pool (36 yr).
Chemical characterization and anti‐anaemia activity of fish protein hydrolysate from Saurida elongata
Authors: Dong Yu‐lian , Sheng Guo‐ying , Fu Jia‐mo , Wen Ke‐wei
Published: June 2005

A low‐value sea fish Saurida elongata was hydrolyzed using papain. Proximate composition analysis of the fish protein hydrolysate showed that the hydrolysate contained 84.7% crude protein, 7.1% ash and 3.5% fat. The determination of amino acid content by o‐phthaldialdehyde pre‐column derivatization reversed‐phase high‐performance liquid chromatography (RP‐HPLC) showed that the hydrolysate contained 20 different amino acids, and the total percentage of eight essential amino acids was as high as 41.5% of the total amino acids, which meant that the hydrolysate could provide a good nitrogen source for human consumption. Peptides were separated by RP‐HPLC using a C‐18 column into more than 14 fractions. Molecular weight distribution of peptides was determined by size‐exclusion HPLC, which indicated that the size of 74.8% of the peptides ranged from 1.0 to 5.0 kDa. Most importantly, the enzymatic hydrolysate from S elongata was shown to contain significant in vivo anti‐anaemia activity on experimental anaemia models induced by blood loss or cyclophosphamide damage to hematogenic mechanism. To the best of our knowledge, this was the first time that the description of hydrolysis of S elongata and the indication of anti‐anaemia activity in the hydrolysate have been reported. Copyright © 2005 Society of Chemical Industry
PREPARE: seeking systemic solutions for technological crisis management
Authors: Davis Beverly J.
Published: June 2005

America's private sector faces an unprecedented challenge in the wake of the 9/11 terrorist attacks. For the first time in the nation's history, its business assets, workers, and critical infrastructures are on the front lines of the battlefield—key targets, and possibly pathways, for future attacks. With terrorism, unconventional declaration of war can be waged, chaos created, and borders crossed by attacking our information highways. Although the catastrophic 9/11 attacks shifted our attention to the United States, the fact remains that Internet attacks against private and public organizations around the world leapt 28% in the 6 months after 9/11. These attacks targeted technology, financial services, and power companies. In order to ‘seek to understand our enemies’, the PREPARE Model of Technological Crisis Management (TCM) along with the application of the Johari Window psychology model will offer business leaders techniques to increase awareness of potential threats to their businesses. The best practice TCM model, a model of continuous process and analysis, takes business cyber‐security to a new level, not only identifying the risks and threats to businesses, but also assessing and creating systemic plans to respond to those risks. Copyright © 2005 John Wiley & Sons, Ltd.
Cultural embeddedness and contextual constraints: knowledge sharing in Chinese and Arab cultures
Authors: Weir David , Hutchings Kate
Published: June 2005

In a recent article Glisby and Holden have noted that the Nonaka and Takeuchi model of knowledge management needs to be used with caution. Its application is not universal because it must be seen primarily as a product of the Japanese cultural context from which it emerged. In the model each of the four modes is interpreted in reference to their embeddedness in Japanese cultural symbols, organizational structures and societal value systems. But we propose that, a fortiori, some aspects of this model do apply to modes of knowledge acquisition and transfer in other cultural contexts. In this paper we review the workings of the model and the four modes with reference to the cultural, organization–structural and value bases of Chinese and Arab societies. We demonstrate that the Nonaka and Takeuchi model maps partially, but differently from both Western and Japanese societies, on to each of these cultural contexts. In these cultures managers and organizational members will share knowledge with those with whom they already have a trustful relationship. This paper explores the implications of the fact that in China and the Arab world the sharing of knowledge cannot be taken for granted outside this context of trustful relationships. Copyright © 2005 John Wiley & Sons, Ltd.
Knowledge management and collaborative model building in the strategy development process
Authors: Adamides Emmanuel , Karacapilidis Nikos
Published: June 2005

Strategy formulation is a knowledge‐intensive social process that involves managers with diverse cognitive spheres. The quality of its outcome depends on the efficient and effective construction of shared context that enables issue‐specific knowledge creation through a process of dialectical argumentation. Group model building is an approach that has been proved to facilitate knowledge externalization, recombination and diffusion for sense making and decision making in strategic discourse. In this line, this paper presents a novel approach for enhancing the strategy process on the basis of collaborative model building and selection through structured dialoguing. Contrary to other approaches, group model building and selection by argumentation (G‐MoBSA) adopts a market perspective of the strategic issue resolution space, on which participants propose their models of the issue and its resolution. Models represent the proponents' particular beliefs and views and are subject to consideration and modifications by all group participants, through a process of formal argumentation. Gradually, models that represent the shared context of the organizational and environmental characteristics with respect to the specific strategic issue emerge. The rationale behind our approach, its elements and suitability to strategy formulation, as well as the characteristics and functionality of Knowledge Breeder, an IS framework that supports it, are presented through a sample session of strategy development in a software development company. Copyright © 2005 John Wiley & Sons, Ltd.
International management of taxi cab operations: a case study in Bangkok
Authors: Skok Walter , Vikiniyadhanee Junthima
Published: June 2005

Taxi cabs are an important form of transport in major cities in the world, but their management and regulation vary significantly between the developed and developing nations. This paper considers a case study that demonstrates how best practice derived from cities in the West may be transferred to one in the East. The paper begins by reporting on the current environment in Bangkok, where there is no central regulatory body to enforce operating standards. The study involved a stakeholder analysis in order to identify the current problems and understand the context within which taxis operate in a Third World setting. The analysis was based on a high‐level model of taxi cab management derived from similar studies in London, New York and Paris, where strict regulatory procedures are enforced. Finally, a comparison between the developed and developing nations is made in order to make recommendations for possible improvements in regulating and managing taxi cab operations in Bangkok. Copyright © 2005 John Wiley & Sons, Ltd.
Lessons learned by participants of distributed software development
Authors: Komi‐Sirviö Seija , Tihinen Maarit
Published: June 2005

The maturation of the technical infrastructure has enabled the emergence and growth of distributed software development. This has created tempting opportunities for companies to distribute their software development, for example, to economically favourable countries so as to gain needed expertise or to get closer to customers. Nonetheless, such distribution potentially creates problems that need to be understood and addressed in order to make possible the gains offered. To clarify and understand the most difficult problems and their nature, a survey of individuals engaged in distributed software development was conducted. The purpose of this survey was to gather and share lessons learned in order to better understand the nature of the software development process when operating in a distributed software development environment and the problems that may be associated with such distributed processes. Through a clear appreciation of the risks associated with distributed development it becomes possible to develop approaches for the mitigation of these risks. This paper presents the results of the survey, focusing on the most serious problems raised by the respondents. Some practical guidelines that have been developed by industry to overcome these problems are also briefly summarized. Copyright © 2005 John Wiley & Sons, Ltd.
Facilitating knowledge management through market mechanism
Authors: Desouza Kevin C. , Awazu Yukika , Yamakawa Shigetaka , Umezawa Masashi
Published: June 2005

While knowledge markets are in existence and have been shown to be valuable, researchers have yet to systematically investigate them. In this paper, we take the first steps towards an investigation into the mechanisms of knowledge markets. Specifically, we employ a mathematical orientation to demonstrate the pivotal role played by pricing schemes in knowledge management agendas. Our work contributes to the field of knowledge management by providing mathematical proofs rather than anecdotal evidence regarding the significance of pricing knowledge in organizations. Copyright © 2005 John Wiley & Sons, Ltd.
Fragmentation of Ziegler‐Natta Catalyst Particles During Propylene Polymerization
Authors: Abboud Mohammed , Denifl Peter , Reichert Karl‐Heinz
Published: June 2005

Summary: Analyzing polymer particles by microscopy technique at different polymerization times provided information regarding the catalyst support break‐up rate and degree of fragmentation during polymerization. Polymer samples were prepared at different polymerization times and melted under a video microscope to track the progress of fragmentation. Studies focused on effect of the catalyst support on the process and degree of catalyst fragmentation. Fragmentation behaviors of both a catalyst without an external support and a silica supported Ziegler‐Natta catalyst were compared. Fragmentation of catalyst was observed to occur in the whole catalyst matrix at the very beginning of polymerization. In the case of the catalyst without an external support, fragmentation was faster and more uniform than that of the silica supported catalyst. Results corresponded to the activity distribution of single catalyst particles as determined by video microscopy. The catalyst without an external support having particles of similar activities showed similar degrees of fragmentation. Conversely, silica supported catalyst having particles of different growth behavior produced particles having different degrees of fragmentation. The rate of increase in the number of catalyst fragments and their surface area with time during polymerization was investigated. Results correlated the catalyst activation period during the initial stage of polymerization to catalyst fragmentation.

Poly(propylene) particles produced with silica supported (upper image) and non‐supported (lower image) Ziegler‐Natta catalysts.

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Poly(propylene) particles produced with silica supported (upper image) and non‐supported (lower image) Ziegler‐Natta catalysts.
Poly(4‐vinylpyridine) Nanocrosslinked by Polyhedral Oligomeric Silsesquioxane
Authors: Liu Yonghong , Meng Fanliang , Zheng Sixun
Published: June 2005

Summary: Octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane (OpePOSS) was used as the crosslinking agent to prepare the nanocrosslinked poly(4‐vinylpyridine) (P4VP) with POSS content up to 55.2 wt.‐%. The formation of the crosslinked structure is ascribed to the macromolecular reaction between pyridine rings of P4VP and epoxide groups of OpePOSS. The POSS‐crosslinked P4VP displayed enhanced glass transition temperatures (Tgs) and an improved thermal stability in terms of the results of thermal analysis.

Crosslinking of poly(4‐vinylpyridine) with octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane.

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Crosslinking of poly(4‐vinylpyridine) with octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane.
Polymer Protein Hybrids
Authors: Smeenk Jurgen M. , Ayres Lee , Stunnenberg Henk G. , van Hest Jan C.M.
Published: June 2005

Structural proteins form an important source of inspiration for materials scientists, because of the well‐defined relationship between their three‐dimensional folding pattern and their physical properties. Incorporation of structural peptide elements in synthetic polymers allows the combination of natural structural control with synthetic versatility. In this report, two approaches to introduce silk‐inspired β‐sheet elements in hybrid block copolymers are described. In our first approach we have successfully applied the controlled radical polymerization technique Atom Transfer Radical Polymerization (ATRP) to construct ABA triblock copolymers, of which the A blocks consist of PMMA and the B block consists of Ala‐Gly‐Ala‐Gly‐methacrylate moieties. This method leads to triblock copolymers with the structural peptide elements in the side chain of the middle block.

Our second approach uses protein engineering for the construction of the β‐sheet element. The latter is converted into a triblock copolymer architecture by modification of both the N and C ends with poly(ethyleneglycol) chains. In this case the B block consists solely of the β‐sheet peptide element. It was demonstrated that it is possible to introduce β‐sheet characteristics in the hybrid material by means of both approaches.
Stereocomplexes of Triblock Poly(lactide‐ PEG2000‐lactide) as Carrier of Drugs
Authors: Bishara Ashgan , Kricheldorf Hans R. , Domb Abraham J.
Published: June 2005

Triblock copolymers of poly(lactide)‐poly(ethylene‐glycol)‐poly(lactide) (PLA‐PEG2000‐PLA) were synthesized by ring‐opening polymerization of lactide and PEG2000 diol as co‐catalyst. Stereocomplexes with particle sizes ranging from nanometers to microns were obtained by mixing acetonitrile solutions of pairs of enantiomeric homopoly(lactide) and the triblock copolymers. The stereocomplexes exhibited higher crystalline melting temperatures than the optically pure polymers. The ratio of PLA terminals in the copolymers had a significant effect on their stereocomplex degradation and drug release. These stereocomplexes were used for the encapsulation of dexamethasone for controlled release applications. Dexamethasone phosphate loading capacity, in vitro release, degradation and stability of polymers and formulation were investigated for one month. An increase in the dexamethsone phosphate content in the stereocomplex or a decrease in the PLA ratio in the copolymer resulted in a faster release of drug and polymer degradation.
Effects of Polymer Modification of an Anti‐Cancer Drug with Poly(ethylene oxide)
Authors: Sohn Jung‐Sun , Jo Byung‐Wook , Hess Michael , Schwark Kirsten , Dehne Stephanie , Zähres Manfred
Published: June 2005

The hydrophobic anti‐cancer drug paclitaxel was modified with the hydrophilic poly(ethylene oxide) to a water‐soluble predrug. The modification of the polymer chain results in a different solution behaviour of the macromolecules compared with the unmodified polymer. The phase diagram of the (quasi)binary system predrug‐water was investigated, and molecular simulations of the predrug were executed in vacuum and in the presence of water. The results are important for further engineering on active drug systems.
Preparation and Characterization of Magnetic Targeted Drug Controlled‐Release Hydrogel Microspheres
Authors: Chen Jie , Yang Liming , Liu Yinfeng , Ding Guowei , Pei Yong , Li Jian , Hua Guofei , Huang Jian
Published: June 2005

Magnetic targeted drug controlled release hydrogel microspheres were prepared by a radiation technique. Ferric oxide granules (size around 50 nm) were used as the core for magnetic target. The PVP ferrogels (ferromagnetic nanoparticles in hydrogel microsphere) were obtained by irradiating an emulsion of Poly (N‐vinylpyrrolidone) PVP/ferromagnetic granule with cobalt 60 γ–ray. The morphology of the PVP ferrogel was studied by both optical and electronic microscopy, respectively. A broad‐spectrum anticancer drug, Bleomycin A5 Hydrochloride (BLM), was immobilized in the ferrogel and the release property of the drug in vitro was studied. The function of targeting and anti‐cancer was studied on the New Zealand White rabbits, based on the implantation of experimental VX2 squamous cell carcinoma in the auricles of the rabbits.
The Role of Synthetic Pharmaceutical Polymer Excipients in Oral Dosage Forms – Poly(ethylene oxide)‐graft‐poly(vinyl alcohol) Copolymers in Tablet Coatings
Authors: Gutzler Rainer , Smulders Maarten , Lange Ronald F.M.
Published: June 2005

A number of tablet coatings are available to provide a controlled release of pharmaceutically active compounds in the stomach or intestine using both instant or sustained released systems. The preferred properties of these tablet coatings are a low solution viscosity (preferable in water) combined with a phase separated morphology, showing good mechanical properties. PEO‐g‐PVAl copolymers have been developed as an instant‐release tablet coating, and were obtained via a conventional radical polymerisation of VAc in the presence of PEO. No free PEO was observed in the PEO‐g‐PVAl copolymers 1f and 1i using 2D LCCC‐SEC and MALDI‐TOF analysis. Next to the requirement of being PEO free, the PEO‐g‐PVAl copolymers show a good combination of film forming properties, a fast dissolution and a low solution viscosity in water. The phase separated morphology, as demonstrated by TEM, DSC, DMTA, and WAXS experiments, should provide the PEO‐g‐PVAl copolymers with relatively constant mechanical properties. A model reaction, using 2‐methoxyethyl‐ether and 1,4,7,10‐tetraoxacyclododecane, has been developed to imitate the grafting reaction of VAc on PEO. Using this model reaction and using the same reaction conditions (temperature, initiator, concentration, VAc:“PEO” ratio, etc.) as applied in the PEO‐g‐PVAl polymerisation procedure, a degree of grafting for PEO of 13±3% was found. Comparing this figure with the results of LCCC‐SEC and MALDI‐TOF measurements, this figure seems a few percent too high, pointing to a slightly increased reactivity of the two model compounds compared to the PEO used.
Preparation and Characterization of pH‐sensitive Hydrogel Film of Chitosan/Poly(acrylic acid) Copolymer
Authors: Yang Liming , Shi Lili , Chen Jie , Pei Yong , Zhu Feng , Xia Yiben
Published: June 2005

A hydrogel film of chitosan/poly(acrylic acid) (CS/PAAc) copolymer with the property of pH sensitivity, was prepared by irradiating the chitosan film, which was then swelled by aqueous AAc solutions of different concentrations. The effects of the feed ratio of chitosan and AAc on the properties of the hydrogels, such as swelling ratio and pH‐sensitivity, were determined. Fourier transform infrared (FT‐IR) spectroscopy was applied in the attenuated total reflectance (ATR) mode for analyzing the structure change of the hydrogels after the treatment in buffer solutions of different pHs.
Synthesis and Properties of Poly(N‐isopropylacrylamide‐co‐acrylamide) Hydrogels
Authors: Chen Jie , Pei Yong , Yang Li‐Ming , Shi Li‐Li , Luo Hao‐Jie
Published: June 2005

Poly (N‐isopropylacrylamide‐co‐acrylamide) [Poly(NIPAAm‐co‐AAm)] with different feed ratios were obtained by radiation polymerization using Co60γ‐rays. Swelling equilibrium data in various media: deionized water, aqueous NaCl solutions and different pH buffer solutions, were determined. It appeared that the lower critical transition temperature (LCST) of the hydrogels increased with an increasing acrylamide content and decreased with increasing ionic strength. Moreover, LCST was affected by pH.
Synthesis of Chain‐End Functionalized PP and Applications in Exfoliated PP/Clay Nanocomposites
Authors: Wang Z.M. , Han H. , Chung T.C.
Published: June 2005

This paper summarizes our research to the preparation of chain‐end functionalized isotactic polypropylene (i‐PP) having a terminal functional group, such as an OH and an NH2. The chemistry involves metallocene‐mediated propylene polymerization using the rac‐Me2Si[2‐Me‐4‐Ph(Ind)]2ZrCl2/MAO complex in the presence of styrene derivatives (St‐f) and hydrogen, which serve as the chain transfer agents. The molecular weight of the resulting i‐PP polymers with terminal OH or NH2 groups (i.e., PP‐t‐OH and PP‐t‐NH2) are inversely proportional to the molar ratio of [St‐f]/[propylene]. Despite the extremely low concentration of functional groups, the high molecular weight NH3+‐terminated PP (PP‐t‐NH3+) exhibits a distinctive advantage over other functional PP polymers containing side chain functional groups or long functional blocks. The terminal hydrophilic NH3+ cation, with good mobility and reactivity, effectively ion‐exchanges the cations (Li+, Na+, etc.) located between the clay interlayers, and anchors the PP chain to the clay surfaces. On the other hand, the remaining rest of the unperturbed, end‐tethered, high molecular weight PP tail exfoliates the clay layers. This exfoliated structure is maintained even after further mixing of the PP‐bearing platelets with pure, neat PP polymers.
Basic Aspects of Polymer Degradation
Authors: Rivaton Agnès , Gardette Jean‐Luc , Mailhot Bénédicte , Morlat‐Therlas Sandrine
Published: June 2005

Knowledge on the mechanisms by which polymers degrade on exposure to natural or artificial ageing has considerably increased during the past few years. One reason for this is the development of novel experimental procedures and analytical techniques. The analyses of the chemical changes permit determining the main degradation routes applicable to the degradation of the properties of materials and ensures the relevance of the laboratory experiments.
Organic Phosphites as Polymer Stabilizers
Authors: Habicher Wolf D. , Bauer Ingmar , Pospíšil Jan
Published: June 2005

The antioxidative action of phosphonites and phosphites depends on their structure, the nature of the polymer to be stabilized and the aging conditions. Phosphorus compounds can act in different ways: as hydroperoxide decomposers (secondary antioxidants), as free‐radical scavengers (primary antioxidants), as well as metal‐complex forming agents. The stabilizing action of phosphites and phosphonites is due to three basic mechanisms: oxidation by hydroperoxides, substitution by alkoxyl radicals and hydrolysis to acidic phosphorus compounds and phenols. Modification of phosphites with additional functional groups such as hindered amine moieties leads to new stabilizing properties. An intramolecular synergistic effect is observed.
Migration of Additives from Poly(vinyl chloride) (PVC) Tubes into Aqueous Media
Authors: Wang Qian , Storm Birgit K.
Published: June 2005

The stability and migration product of medical PVC tubes plasticized with polyadipates were investigated by ageing in phosphate buffer at pH 1.679 and water at different temperatures. Changes in the PVC tubes were studied by water absorption, weight loss, Fourier infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The low molecular weight migration product that was released was extracted and silylanized before gas chromatography/mass spectroscopy (GC/MS) identification and quantification. After 70 days, the weight loss was less than 0.5% and only a small amount of adipic acid migrated when a tube was aged at 37°C in water and phosphate buffer (pH 1.679), and at 70°C in water after 56 days. However, when aged at 70 and 110°C, gradual deactivation of heat stabilizer after 21 days of ageing in buffer solution and separation of plasticizer from PVC matrix occurred. When the tube was aged at 110°C, significant degradation of both polyadipates and PVC were observed. Adipic acid and 1,4‐butanediol monomers and oligomers of polyadipate were the major migration products from polyadipates in the water ageing solution, while only a relatively high amount of adipic acid was identified as the main product in the buffer ageing solution.
Investigation of Degradation of Structural Adhesives under Influence of Chemicals
Authors: Kjærside Storm Birgit , Gwisdalski Milosz , Lindvang Dan , Rann Michael
Published: June 2005

Structural adhesives are used for joining materials also under conditions, where they through the application will be influenced by many different chemicals. The adhesives can – if not protected from the chemical influence – be degradated of the chemicals. The degradation can because of the different structures of the polymers in the adhesives result in lower strength of the joining area, but can also give higher strength but brittleness.

Information of the structures of the structural adhesives used in the project have been taken from the data sheets from the manufacturers and have been compared with investigation of the structures by FTIR and DSC. In the laboratory the HSP's (Hansen Solubility Parameters) of the adhesives has been determined and compared with the theoretically estimated HSP's. The estimation has mainly been done by Lydersens group contribution method.

The chemical resistance of the adhesives have been foreseen by using HSP's of the adheisves and compared them with the HSP's of the chemicals.

The structural adhesives were most of the epoxy types and of the polyurethane types with different curing systems. The structural adhesives should all have high strength and an opening time of more than 30 minutes. They were in the laboratory cured up after the specifications from the manufacturer and were stored one week after curing before they were influenced by hte chosen chemicals. The chemicals were chosen from their functional groups.

In the laboratory the adhesives were influenced by different chemicals at room temperarture and under elevated temperature and under different periods to develope the degradation curves for the different chemicals and to foresee the degradation time of the adhesives before their properties were not acceptable any more. The structure after influence of the chemicals is studied by FTIR. The results of the investigations have been that it is possible to estimate the degradation by using the HSP's of the adhesives and the chemicals, but to estimate the time before degradation has been so serious that the properties of the adhesives are not acceptable any more, it is necessary to add laboratory investigations to the HSP comparisons of adhesives and chemicals. The comparison of the HSP and of the chemicals by which the adhesives can be in its lifetime has seen to be usefull especially if the chemicals are pesticides.