bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of Micro/Macroporous Hierarchical Spheres of Titanosilicate Umbite
Authors: Sebastián Víctor , Téllez Carlos , Coronas Joaquín , Santamaría Jesús
Published: April 2008

Polycrystalline spheres of up to 2 mm diameter of microporous titanosilicate K2TiSi3O9·H2O with umbite structure (Ti‐umbite) were prepared without the use of organic structuring agents. The spheres, while preserving the inherent microporosity of the umbite type‐material, are organized as hierarchical materials with macropores in the 0.1–1.4‐μm size range. Ti‐umbite spheres were only produced by hydrothermal synthesis under rotation conditions, at 230 °C by using a solution with the following molar composition:0.284 K2O/0.287 Na2O/SiO2/0.095 TiO2(anatase)/30.8 H2O, andit was observed that the synthesis time and the rotation speed of the autoclave influenced the particle size distribution. When the procedure was carried out at 30 rpm and for 48 h, the size of the Ti‐umbite spheres adjusted well to a normal distribution, with a statistical mode of 492 ± 13 μm. Also, under these conditions the amount of unreacted TiO2 anatase, which has a key role in the formation of the Ti‐umbite spheres, was only 14.4 wt.‐%. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Mo‐Catalyzed Cross‐Metathesis Reaction of Propynylferrocene
Authors: Bobula Tomáš , Hudlický Jason , Novák Petr , Gyepes Róbert , Císařová Ivana , Štěpnička Petr , Kotora Martin
Published: April 2008

Catalysts formed in situ from [Mo(CO)6] and halophenols in dichloromethane efficiently promote cross metathesis reactions of (prop‐1‐yn‐1‐yl)ferrocene with various functionalized alkynes to give the corresponding alkynylferrocenes with good selectivity and yields. Optimization of the reaction conditions by changing the phenol component has been carried out, revealing a critical influence of the phenol structure on the reaction yield. The structures of selected compounds were determined by single‐crystal X‐ray diffraction, and the results (particularly the crystal packing) were correlated with DFT calculations. In addition, the series of alkynes 4‐XC6H4C≡CFc (Fc = ferrocenyl) differing by the substituent X was studied by electrochemical methods, manifesting a good correlation between the redox potential of the ferrocene/ferrocenium couple and the Hammett σp constants of the remote substituents X. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Guanidine‐Catalyzed Asymmetric Synthesis of 2,2‐Disubstituted Chromane Skeletons by Intramolecular Oxa‐Michael Addition
Authors: Saito Noriko , Ryoda Akemi , Nakanishi Waka , Kumamoto Takuya , Ishikawa Tsutomu
Published: April 2008

The guanidine‐catalyzed 6‐exo‐trig‐type intramolecular asymmetric oxa‐Michael addition of α,β‐unsaturated esters with a 2‐hydroxyaryl moiety at the C‐5 carbon has been examined for the construction of chromane skeletons with a quaternary carbon chiral center. The bulkiness of the alkyl group and the E/Z geometry of the α,β‐unsaturated ester function played important roles in the asymmetric induction and (4S,5S)‐2‐[(R)‐1‐hydroxymethyl‐2‐phenylethylimino]‐1,3‐dimethylimidazolidine (or its enantiomer) carrying aryl pendants at the 4‐ and 5‐positions was found to be the most effective catalyst among 18 chiral guanidines examined. In this way, the Z isomer of the less bulky methyl ester was subjected to the cyclization reaction, affording chiral chromane in up to 83 % yield with 76 % ee. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Preparation of Novel Arrays Silver Nanoparticles Modified Polyrutin Coat‐Paraffin‐Impregnated Graphite Electrode for Tyrosine and Tryptophan's Oxidation
Authors: Jin Guan‐Ping , Peng Xia , Chen Qun‐Zhi
Published: April 2008

A novel array silver nanoparticles and Rutin complex film modified paraffin‐impregnated graphite electrode was proposed in this work (denoted as Ag/Rutin/WGE). The characteristics were investigated by the field emission scanning electron microscopy (FE‐SEM), infrared spectra (IR), UV‐visible (UV), X‐ray photoelectron spectroscopy (XPS) and electrochemical techniques. Silver ions were gradually chelated by polyrutin film at 4′‐oxo‐5′‐OH and 5‐OH‐4‐oxo sites accompanying adsorption, then. Silver nanoparticles were highly‐dispersed electrodeposited on polyrutin film. The electrochemical behaviors of tyrosine (Tyr) and tryptophan (Trp) were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The Ag/Rutin/WGE electrode shows overlapping catalysis for the oxidation of Tyr and Trp. The linear response of Tyr and Trp were 0.3–10.0 and 0.7–70.0 μM with detection limit of 0.07 and 0.1 μM in a signal‐to‐noise ratio of 3.
Improved repeatability and matrix‐assisted desorption/ionization – time of flight mass spectrometry compatibility in capillary isoelectric focusing
Authors: Silvertand Linda H. H. , Toraño Javier Sastre , de Jong Gerhardus J. , van Bennekom Wouter P.
Published: April 2008

Low repeatability of migration time, peak area, and linearity (pI vs. mobilization time) is a problem often encountered in capillary IEF (cIEF) and is mainly caused by protein precipitation and protein–wall interactions. In order to study the influence of these phenomena, the effect of different classes of additives on repeatability of migration time, peak area and linearity of a mixture of seven model proteins has been investigated. Moreover, the influence of these additives on protein signal suppression in MALDI‐TOF MS has been studied. The optimal ampholyte blend (stabilizes pH gradient) to be used depends on the selected UV detection wavelength. All tested ampholyte blends show a significant and comparable signal suppression in MS. The best detergent (to prevent precipitation and wall interaction) should be determined for each sample individually, but generally polyethylene oxide and zwitterionic detergents show good repeatability for migration time (RSD <4.5%) and peak area (majority <10%). The RSD of R2 is <1.3% for the hydrophilic protein mixture. However, these components cause severe signal suppression in MS. Therefore glucoside detergents should preferably be used for MS coupling. Viscosity‐increasing agents (for hydrodynamic wall coating and to minimize diffusion) in particular cellulose derivatives, give good repeatability for migration times (RSD <4.5% at lower concentrations), peak area (except for high concentration methylcellulose and hydroxyethylcellulose all within 7.5%), and correlation (pI vs. migration time), but severe signal suppression is observed in MALDI‐TOF MS. Overall, cIEF repeatability and linearity can significantly be improved by adding the appropriate components. However, when the system is coupled to a MALDI‐TOF MS, compromises have to be made between high repeatability and linearity on one hand and MS signal intensity on the other.
Development of a low‐flow multiplexed interface for capillary electrophoresis/electrospray ion trap mass spectrometry using sequential spray
Authors: Chen Chao‐Jung , Li Fu‐An , Her Guor‐Rong
Published: April 2008

A multiplexed CE‐MS interface using four low‐flow sheath liquid ESI sprayers has been developed. Because of the limited space between the low‐flow sprayers and the entrance aperture of the ESI source, multichannel analysis is difficult using conventional rotating plate approaches. Instead, a multiplexed low‐flow system was achieved by applying an ESI potential sequentially to the four low‐flow sprayers, resulting in only one sprayer being sprayed at any given time. The synchronization of the scan event and the voltage relays was accomplished by using the data acquisition signal from the IT mass spectrometer. This synchronization resulted in the ESI voltage being sequentially applied to each of the four sprayers according to the corresponding scan event. With this design, a four‐fold increase in analytical throughput was achieved. Because of the use of low‐flow interfaces, this multiplexed system has superior sensitivity than a rotating plate design using conventional sheath liquid interfaces. The multiplexed design presented has the potential to be applied to other low‐flow multiplexed systems, such as multiplexed capillary LC and multiplexed CEC.
Development of a quantitative, validated Capillary electrophoresis‐time of flight – mass spectrometry method with integrated high‐confidence analyte identification for metabolomics
Authors: Timischl Birgit , Dettmer Katja , Kaspar Hannelore , Thieme Marian , Oefner Peter J.
Published: April 2008

A CE‐MS method was developed and validated for the quantitative analysis of negatively charged metabolites by making use of the high mass accuracy and the quantitation capabilities of a TOF mass analyzer in combination with automated feature extraction and database search. Metabolites of the central carbon metabolism were quantified with an LOD and lower LOQ (LLOQ) of 0.2–2 and 1–4 µM, respectively. The method was used to elucidate metabolic changes in the Escherichia coli deletion mutant PntAB‐UdhA that lacks nicotinamide nucleotide transhydrogenase function, under both stationary and exponential growth conditions. The reproducibility of metabolite extraction and CE‐TOF‐MS analysis ranged from 3.7 to 22.7 and 7.9 to 22.6%, respectively, while the biological variance was 3.4–31.3%. We observed significant differences in metabolite abundance, particularly in the citrate cycle, between wild‐type and mutant E. coli. Overall, more than 600 features were found by automated feature detection, which resulted in ∼150 high‐confidence metabolite identifications. Concomitant analyses with two different GC‐MS methods allowed not only crossvalidation of the quantitative results obtained by the various methods, but also led to a more comprehensive coverage of the E. coli metabolome.
Simultaneous Application of Glucose Oxidases and Peroxidases in Bleaching Processes
Authors: Opwis K. , Knittel D. , Schollmeyer E. , Hoferichter P. , Cordes A.
Published: April 2008

Peroxidases (POD) are used in textile decoloration and bleaching processes, but these enzymes are unfortunately inactivated rapidly at high hydrogen peroxide concentrations. A new concept has therefore been developed, which is based on a simultaneous application of glucose oxidase and peroxidase. Starting with glucose as a substrate for glucose oxidase (GOD), hydrogen peroxide was generated in situ. The freshly formed substrate H2O2 was immediately used by the POD oxidizing colored compounds in dyeing baths. For example, 20 mg of the dyestuff Sirius Supra Blue®FGG 200 % could be decolorized using 125 mg glucose which corresponds to 24 mg hydrogen peroxide. These experiments show that the enzyme cascade works in principle in homogeneous decoloration processes. The enzymes were not degraded by the oxidant, because under these conditions the stationary peroxide concentration is nearly zero over the whole reaction time. Moreover, experiments were carried out to check if this combined system with GOD, glucose and POD could be used even in heterogeneous systems such as the textile bleaching of natural cotton fibers. Starting from 55, a significant higher degree of whiteness (according to Berger) up to 66 could be obtained.
Methodology for the development of analytical fragility curves for retrofitted bridges
Authors: Padgett Jamie E. , DesRoches Reginald
Published: April 2008

Fragility curves for retrofitted bridges indicate the influence of various retrofit measures on the probability of achieving specified levels of damage. This paper presents an analytical methodology for developing fragility curves for classes of retrofitted bridge systems. The approach captures the impact of retrofit on the vulnerability of multiple components, which to date has not been adequately addressed, and results in a comparison of the system fragility before and after the application of different retrofit measures. Details presented include analytical modeling, uncertainty treatment, impact of retrofit on demand models, capacity estimates, and component and system fragility curves. The findings indicate the importance of evaluating the impact of retrofit not only on the targeted response quantity and component vulnerability but also on the overall bridge fragility. As illustrated by the case study of a retrofitted multi‐span continuous (MSC) concrete girder bridge class, a given retrofit measure may have a positive impact on some components, yet no impact or a negative impact on other critical components. Consideration of the fragility based only on individual retrofitted components, without regard for the system, may lead to over‐estimation or under‐estimation of the impact on the bridge fragility. The proposed methodology provides an opportunity to effectively compare the fragility of the MSC concrete bridge retrofit with a range of different retrofit measures. The most effective retrofit in reducing probable damage for a given intensity is a function of the damage state of interest. Copyright © 2008 John Wiley & Sons, Ltd.
The foundations and evolution of institutional research
Authors: Volkwein J. Fredericks
Published: April 2008

Do all institutional research offices look alike? This chapter examines the size, function, and structure of institutional research activities and offices across the United States.
The role of institutional research in conducting comparative analysis of peers
Authors: Trainer James F.
Published: April 2008

In the age of Google, data appear to be plentiful. The secret is knowing where to obtain useful and relevant data, how to access them, and how to draw meaningful conclusions from them.
The role of institutional research in understanding and describing faculty work
Authors: Middaugh Michael F. , Kelly Heather A. , Walters Allison M.
Published: April 2008

Understanding faculty workload is critical in assessing and describing institutional effectiveness. The Delaware Study of Instructional Costs and Productivity is one example.
Typical institutional research studies on students: Perspective and examples
Authors: Delaney Anne Marie
Published: April 2008

Institutional researchers can provide valuable information about student populations. Which of the myriad institution‐specific research studies that are currently conducted are most valuable?
Accreditation and institutional research: The traditional role and new dimensions
Authors: Brittingham Barbara , O'Brien Patricia M. , Alig Julie L.
Published: April 2008

Institutions are increasingly called on to supply evidence that their educational mission is being achieved. The accreditation self‐study is one opportunity to exploit the expertise of the institutional research office in collecting important data for institutional improvement.
Sinusoidal endothelial cells prevent rat stellate cell activation and promote reversion to quiescence
Authors: DeLeve Laurie D. , Wang Xiangdong , Guo Yumei
Published: April 2008

Capillarization precedes hepatic fibrosis. We hypothesize that capillarization of sinusoidal endothelial cells (SEC) is permissive for hepatic stellate cell (HSC) activation and therefore permissive for fibrosis. We examined whether freshly isolated SECs prevent activation of HSCs and promote reversion to quiescence, and whether this effect was lost in capillarization. HSCs were cultured alone or co-cultured with differentiated or capillarized SECs. Results: Co-culture with freshly isolated SECs markedly decreased HSC activation after 3 days in culture, but co-culture with capillarized SEC had no effect. Inhibition of nitric oxide (NO) synthesis abolished SEC suppression of HSC activation. Activated HSCs reverted to quiescence when co-cultured with SEC plus vascular endothelial growth factor (VEGF) (that is, with SECs that maintained differentiation), but co-culture with capillarized SECs did not. Reversion of activated HSCs to quiescence in the presence of SECs plus VEGF was abolished by inhibition of NO synthesis. To establish whether there was indeed reversion, activated and quiescent HSCs were counted before and 3 days after adding freshly isolated SECs plus VEGF to activated HSCs, and proliferation was quantified in quiescent HSCs; the stoichiometry demonstrated reversion.

Conclusion:

Differentiated SECs prevent HSC activation and promote reversion of activated HSCs to quiescence through VEGF-stimulated NO production. Capillarized SECs do not promote HSC quiescence, because of loss of VEGF-stimulated NO production. (Hepatology 2008.)
Levels of ATP in different organic wastes under composting conditions
Authors: Montes Juan Antonio , Sánchez Antoni
Published: April 2008

BACKGROUND: The concentration of ATP in selected samples from the composting process of several organic wastes (municipal solid wastes, wastewater sludge, animal by‐products and cow manure) has been determined in order to characterize the aerobic biological activity of such wastes.

RESULTS: The values obtained ranged from 0 (in old stable compost from cow manure) to 0.07 µmol ATP g−1 dry matter in thermophilic samples of municipal solid wastes composting. In general, it was found that ATP levels were in agreement with the stage of the composting process (initial stage, thermophilic period and maturation). On the other hand, ATP concentration correlated well (P < 0.05) with the overall respiration activity during a complete composting process of municipal solid waste at full scale.

CONCLUSION: ATP concentration can be used to determine the biological activity of organic solid wastes in different stages of their biological treatment and to predict compost stability prior to soil application. Copyright © 2008 Society of Chemical Industry
Lovastatin production by Aspergillus terreus in a two‐staged feeding operation
Authors: Porcel Elisa M Rodríguez , López Jose L Casas , Pérez Jose A Sánchez , Chisti Yusuf
Published: April 2008

BACKGROUND: Lovastatin is known to inhibit its own synthesis in the fungus Aspergillus terreus. Therefore, the use of a fermentation strategy that continuously removes some of the lovastatin produced from the bioreactor can enhance its productivity. This paper reports on the effects of dilution rate and the composition of the feed medium on lovastatin production by A. terreus.

RESULTS: The feeding strategy consisted of an initial batch/fed‐batch phase and a semi‐continuous culture phase in which the pelleted biomass was retained inside a slurry bubble column. A nitrogen‐free medium was fed at various fixed dilution rates in the semi‐continuous phase. In experiments that were designed to assess the effects of the composition of the medium, the dilution rate was held at 0.42 d−1, but different feed media were used in separate runs. The best two‐staged production strategy was shown to consist of a 96 h batch/fed‐batch phase that used a nutritionally complete medium. This was followed by a semi‐continuous operation using a medium that was free of both nitrogen and carbon sources.

CONCLUSION: Semi‐continuous operation enhanced productivity of lovastatin by 315% compared with a conventional batch operation. The optimal dilution rate in semi‐continuous operation was about 0.42 d−1. Copyright © 2008 Society of Chemical Industry
Revisiting Wittgenstein on Köhler and Gestalt psychology
Authors: Benjafield John G.
Published: April 2008

In an article in this journal, Nicholas Pastore rejected Ludwig Wittgenstein's critique of Wolfgang Köhler and Gestalt psychology. Pastore appears not to have appreciated Wittgenstein's argument that Köhler mistook conceptual questions for factual ones. A simi‐lar confusion seems to underlie at least some aspects of contemporary neuroscience. Be that as it may, Wittgenstein has had minimal influence on the research practices of psychologists while Köhler remains influential. This outcome would not have surprised Wittgenstein, who predicted that scientists would not see his work as relevant to theirs. © 2008 Wiley Periodicals, Inc.
Toward a transnational history of the social sciences
Authors: Heilbron Johan , Guilhot Nicolas , Jeanpierre Laurent
Published: April 2008

Historical accounts of the social sciences have too often accepted local or national institu‐tions as a self‐evident framework of analysis, instead of considering them as being embed‐ded in transnational relations of various kinds. Evolving patterns of transnational mobility and exchange cut through the neat distinction between the local, the national, and the inter‐national, and thus represent an essential component in the dynamics of the social sciences, as well as a fruitful perspective for rethinking their historical development. In this pro‐grammatic outline, it is argued that a transnational history of the social sciences may be fruitfully understood on the basis of three general mechanisms, which have structured the transnational flows of people and ideas in decisive ways: (a) the functioning of international scholarly institutions, (b) the transnational mobility of scholars, and (c) the politics of trans‐national exchange of nonacademic institutions. The article subsequently examines and illustrates each of these mechanisms. © 2008 Wiley Periodicals, Inc.
MRI‐compatible manipulator with remote‐center‐of‐motion control
Authors: Hata Nobuhiko , Tokuda Junichi , Hurwitz Shelley , Morikawa Shigehiro
Published: April 2008

Purpose

To develop and assess a needle‐guiding manipulator for MRI‐guided therapy that allows a physician to freely select the needle insertion path while maintaining remote center of motion (RCM) at the tumor site.

Materials and Methods

The manipulator consists of a three‐degrees‐of‐freedom (DOF) base stage and passive needle holder with unconstrained two‐DOF rotation. The synergistic control keeps the Virtual RCM at the preplanned target using encoder outputs from the needle holder as input to motorize the base stage.

Results

The manipulator assists in searching for an optimal needle insertion path which is a complex and time‐consuming task in MRI‐guided ablation therapy for liver tumors. The assessment study showed that accuracy of keeping the virtual RCM to predefined position is 3.0 mm. In a phantom test, the physicians found the needle insertion path faster with than without the manipulator (number of physicians = 3, P = 0.001). However, the alignment time with the virtual RCM was not shorter when imaging time for planning were considered.

Conclusion

The study indicated that the robot holds promise as a tool for accurately and interactively selecting the optimal needle insertion path in liver ablation therapy guided by open‐configuration MRI. J. Magn. Reson. Imaging 2008. © 2008 Wiley‐Liss, Inc.
Real‐time fast strain‐encoded magnetic resonance imaging to evaluate regional myocardial function at 3.0 Tesla: Comparison to conventional tagging
Authors: Korosoglou Grigorios , Youssef Amr A. , Bilchick Kenneth C. , Ibrahim El‐Sayed , Lardo Albert C. , Lai Shenghan , Osman Nael F.
Published: April 2008

Purpose

To compare the utility of the real‐time technique fast strain‐encoded magnetic resonance imaging (fast‐SENC) for the quantification of regional myocardial function to conventional tagged magnetic resonance imaging (MRI).

Materials and Methods

Healthy volunteers (N = 12) and patients with heart failure (N = 7) were examined using tagged MRI and fast‐SENC at 3.0T. Circumferential strain was measured using fast‐SENC in six endo‐ and six subepicardial regions in the basal‐, mid‐, and apical‐septum and the basal‐, mid‐, and apical‐lateral wall from the four‐chamber view. These measurements were plotted to tagging, in corresponding myocardial segments.

Results

Peak systolic strain (Ecc) and early diastolic strain rate (Ecc/second) acquired by fast‐SENC correlated closely to tagged MRI (r = 0.90 for Ecc and r = 0.91 for Ecc/second, P < 0.001 for both). Both fast‐SENC and tagging identified differences in regional systolic and diastolic function between normal myocardium and dysfunctional segments in patients with heart failure (for fast‐SENC: Ecc = −21.7 ± 2.7 in healthy volunteers vs. −12.8 ± 4.2 in hypokinetic vs. 0.6 ± 3.8 in akinetic/dyskinetic segments, P < 0.001 between all; Ecc/second = 104 ± 20/second in healthy volunteers vs. 37 ± 9/second in hypokinetic vs. −16 ± 15/second in akinetic/dyskinetic segments, P < 0.001 between all). Quantitative analysis was more time‐consuming for conventional tagging than for fast‐SENC (time‐spent of 3.8 ± 0.7 minutes vs. 9.5 ± 0.7 minutes per patient, P < 0.001).

Conclusion

Fast‐SENC allows the rapid and accurate quantification of regional myocardial function. The information derived from fast‐SENC during a single heartbeat seems to be superior or equal to that acquired by conventional tagging during several heart cycles and prolonged breathholds. J. Magn. Reson. Imaging 2008. © 2008 Wiley‐Liss, Inc.
Microtensile bond strength of different adhesive systems in dentin irradiated with Er:YAG laser
Authors: Sierpinsky L M G , Lima D M , Candido M S M , Bagnato V S , Porto-Neto S T
Published: April 2008

The objective this study was to evaluate in vitro the bond strength of two etch-and-rise and one self-etching adhesive system after dentin irradiation with Er:YAG (erbium: yttrium aluminum garnet) laser using microtensile test. The results revealed that the groups treated with laser Er:YAG presented less tensile bond strength, independently to the adhesive system used. The prompt L-pop adhesive presented less microtensile bond strength compared to the other adhesives evaluated. There was no difference between single bond and excite groups. The adhesive failures were predominant in all the experimental groups. The Er:YAG laser influenced negatively bond strength values of adhesive systems tested in dental substrate.
One‐Step Growth of ca. 2–15 nm Polymer Thin Films on Hydrogen‐Terminated Silicon
Authors: Blake Robert B. , Pei Lei , Yang Li , Lee Michael V. , Conley Hiram J. , Davis Robert C. , Shirahata Naoto , Linford Matthew R.
Published: April 2008

Here we show direct polymer growth on hydrogen‐terminated silicon (SiH) as a one‐step process. SiH is immersed in a heated solution of an initiator, a monomer, and a crosslinker. The resulting polymer films are 2–15 nm thick, the thickness can be tuned by varying reaction conditions, and the polymer films are robust. Thinner films are obtained in polymer growth without crosslinker. Radicals produced by the initiator and in growing polymer chains may pluck H atoms from SiH to make reactive dangling bonds. These in turn appear to react with monomers and crosslinkers. Crosslinkers tethered through one double bond may be grafted into polymer chains growing in solution. Surface reactivity is demonstrated by optical ellipsometry, X‐ray photoelectron spectroscopy, atomic force microscopy, and wetting.

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A defect correction method for the time‐dependent Navier‐Stokes equations
Authors: Labovschii A.
Published: April 2008

A method for solving the time dependent Navier‐Stokes equations, aiming at higher Reynolds' number, is presented. The direct numerical simulation of flows with high Reynolds' number is computationally expensive. The method presented is unconditionally stable, computationally cheap, and gives an accurate approximation to the quantities sought. In the defect step, the artificial viscosity parameter is added to the inverse Reynolds number as a stability factor, and the system is antidiffused in the correction step. Stability of the method is proven, and the error estimations for velocity and pressure are derived for the one‐ and two‐step defect‐correction methods. The spacial error is O(h) for the one‐step defect‐correction method, and O(h2) for the two‐step method, where h is the diameter of the mesh. The method is compared to an alternative approach, and both methods are applied to a singularly perturbed convection–diffusion problem. The numerical results are given, which demonstrate the advantage (stability, no oscillations) of the method presented. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
Error estimates of finite volume element method for the pollution in groundwater flow
Authors: Zhang Zhiyue
Published: April 2008

In this article, we study the finite volume element methods for numerical solution of the pollution in groundwater flow in a two‐dimensional convex polygonal domain. These type flow are uniform transport in a fully saturated incompressible porous media, which may be anisotropic with respect to hydraulic conductivity, but features a direction independent of dispersivity. A fully finite volume scheme is analyzed in this article. The discretization is defined via a planar mesh consisting of piecewise triangles. Optimal order error estimates in H1 and L2 norms are obtained. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
Application of 16O/18O reverse proteolytic labeling to determine the effect of biofilm culture on the cell envelope proteome of Porphyromonas gingivalis W50
Authors: Ang Ching‐Seng , Veith Paul D. , Dashper Stuart G. , Reynolds Eric C.
Published: April 2008

Porphyromonas gingivalis is an oral pathogen linked to chronic periodontitis. The bacterium exists as part of a polymicrobial biofilm accreted onto the tooth surface. An understanding of the changes to the proteome especially of the cell envelope of biofilm cells compared with planktonic cells could provide valuable insight into the molecular processes of biofilm formation. To establish which proteins changed in abundance between the planktonic and biofilm growth states, the cell envelope fractions of two biological replicates of P. gingivalis cultivated in a chemostat were analysed. Proteins were separated by 1‐D SDS‐PAGE, in‐gel digested with trypsin in the presence of H216O or H218O and identified and quantified by LC‐MALDI TOF/TOF‐MS. Using a reverse labeling strategy we identified and quantified the changes in abundance of 81 P. gingivalis cell envelope proteins. No form of bias between the labels was observed. Twenty four proteins increased in abundance and 18 decreased in abundance in the biofilm state. A group of cell‐surface located C‐Terminal Domain family proteins including RgpA, HagA, CPG70 and PG99 increased in abundance in the biofilm cells. Other proteins that exhibited significant changes in abundance included transport related proteins (HmuY and IhtB), metabolic enzymes (FrdAB) and immunogenic proteins.
Proteomic investigation of the adaptation of Lactococcus lactis to the mouse digestive tract
Authors: Roy Karine , Meyrand Mickaël , Corthier Gérard , Monnet Véronique , Mistou Michel‐Yves
Published: April 2008

Lactic acid bacteria are used on an industrial scale for the manufacturing of dairy products. It is now intended to develop novel applications of lactic acid bacteria that could be used as living vehicles for the targeting of antigens or therapeutics to the digestive mucosa. The aim of this study was to analyze the adaptations of Lactococcus lactis, a model lactic acid bacteria to the digestive tract and to identify functions required for colonization of the intestine. For this purpose, we combined gnotobiology with proteomics: axenic mice were colonized with a dairy L. lactis strain and the bacterial proteome was examined by 2‐DE. As compared to cultures in broth, the proteome profile of bacteria grown in the intestine indicates the activation of metabolic pathways involved in various carbon sources assimilation and suggests the adoption of a mixed acids fermentative metabolism. We identified the product of the ywcC gene as essential for the colonization of the digestive tract and demonstrated that the corresponding gene product (YwcC) possesses a phosphogluconolactonase activity, suggesting an important role of the pentose phosphate pathway for the development of L. lactis in the digestive environment.
Serum protein profiling in mice: Identification of Factor XIIIa as a potential biomarker for muscular dystrophy
Authors: Alagaratnam Sharmini , Mertens Bart J. A. , Dalebout Johannes C. , Deelder André M. , van Ommen Gert‐Jan B. , den Dunnen Johan T. , 't Hoen Peter A. C.
Published: April 2008

Protein profiling in blood serum by fractionation and MS analysis has been applied in mice to assess its applicability as a fast, economical alternative to current DNA and RNA analyses for diagnosis of neuromuscular disorders. Mass spectra of peptides and proteins were generated using serum from dystrophin‐deficient mdx and control mice by WCX ClinProt bead fractionation, followed by MALDI‐MS. Double cross‐validatory linear discriminant and logistic regression data analysis methods were compared with a new Bayesian logistic regression method. These were evaluated on their ability to discriminate between healthy and dystrophic samples, and to identify the discriminatory peaks in the mass spectra. All three approaches classified the spectra with comparable misclassification rates (between 18.4 and 20.6%), with much overlap between the differential peaks identified between the methods. The differential peak pattern from the Bayesian method was sparser and easier to interpret than from the other two methods, without compromising classifying strength. One of the two main differentiating peaks at m/z 3908 was identified as an N‐terminal peptide of coagulation Factor XIIIa, previously identified in human serum. This work underlines the translational aspect of serum protein profiling in mice and supports a further study with serum from patients with neuromuscular disorders.
Synthesis and characterization of carboxylic acid‐terminated polyisobutylenes
Authors: Kemp Lisa K. , Donnalley Andrew B. , Storey Robson F.
Published: April 2008

tert‐Chloride‐terminated polyisobutylenes (PIB) (1020 ≤Mn≤ 6700 g/mol) were dehydrochlorinated nonregiospecifically using basic alumina, or regiospecifically either via potassiumtert‐butoxide orin situquenching of quasiliving PIB. Olefin‐terminated PIBs were quantitatively ozonized at −78 °C using hexane/methylene chloride/methanol, 62/31/7 (v/v/v) cosolvents, and an ozone generator, employing pure oxygen as source gas. The primary ozonides were reduced using trimethyl phosphite to yield pure PIB methyl ketone fromexo‐olefin PIB, and a mixture of PIB methyl ketone and PIB aldehyde from mixed olefin‐PIB. PIB methyl ketone was oxidized to carboxylate via the haloform reaction; titration revealed near‐quantitative functionalization, but the reaction was slow. Tetrahalomethane oxidation was identified as a preferred alternative method, and was conducted using either CCl4as the reaction solvent, THF as the solvent with CCl4in reagent amounts, or hexane as the solvent with a phase‐transfer catalyst and CCl4in reagent amounts. The system using hexane, with tetra‐n‐butyl ammonium chloride as phase‐transfer catalyst, showed complete conversion in ∼ 4 h. PIB carboxylic acid was recovered by acidification and isolation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3229–3240, 2008
Graft copolymerization of 2‐methacryloyloxyethyl phosphorylcholine to cellulose in homogeneous media using atom transfer radical polymerization for providing new hemocompatible coating materials
Authors: Yan Lifeng , Ishihara Kazuhiko
Published: April 2008

To develop new hemopurification systems based on cellulose membrane, we synthesized a graft copolymer of cellulose with poly(2‐methacryloyloxyethyl phosphorylcholine) (MPC) by a metal‐catalyzed atom transfer radical polymerization process in homogeneous media. First, cellulose was dissolved in a DMAc/LiCl solution system, and it reacted with 2‐bromoisobutyloyl bromide to produce macroinitiator (cell‐BiB). Then, MPC was polymerized to the cellulose backbone in a homogeneous DMSO/methanol mixture solution in the presence of cell‐BiB. Characterization with FT‐IR, NMR, and GPC measurements showed that there obtained a graft copolymer of cellulose backbone and poly(MPC) side chains (cell‐PMPC) with well‐defined structure, indicating a controlled/“living” radical polymerization. The proteins adsorption studies showed that cellulose membranes modified by the as‐prepared cell‐PMPC owns good protein adsorption resistance. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3306–3313, 2008
Extension of RDG‐FA for Scattering Prediction of Aggregates of Soot Taking into Account Interactions of Large Monomers
Authors: Yon Jérôme , Rozé Claude , Girasole Thierry , Coppalle Alexis , Méès Loïc
Published: April 2008

The characterization of soot fractal aggregate, i.e., morphology, size, number and volume fraction, by optical diagnostics is very widespread since it is a sensitive and nonintrusive technique. In general, light absorption or scattering by fractal aggregates is quantitatively interpreted by the Rayleigh‐Debye‐Gans for Fractal Aggregates (RDG‐FA) theory due to its simplicity. Nevertheless, important conditions have to be obeyed for the correct use of this theory. Among them, aggregates and primary particles have to be very small in comparison to the wavelength. In addition, internal scattering must be negligible. Moreover, the form factor functions that allow the fractal morphology to be taken into account have been established for a polydispersed population. In contrast to previous studies that evaluated the valid RDG‐FA range by comparing the difference between rigorous calculations and the RDG‐FA approach, the aim of the present study is to evaluate possible corrections that could be applied to the classical RDG‐FA formula in order to take into account of aggregates and primary particles internal multiscattering. Therefore, new generalized form factors are proposed allowing the evaluation of the optical properties of one aggregate with a primary particle diameter of up to 90 nm, without any assumptions concerning aggregate complex internal interactions. The presented results are based on the assumption that DDSCAT (Discrete Dipole Approximation) provides accurate results, with a wavelength, λ = 632 nm, a soot fractal dimension of 1.8 and Dalzel and Sarofim optical index, m = 1.57 – i0.56.
Excited state properties of neutral and charged ter‐fluorene with and without a keto‐defect
Authors: Beenken W. J. D. , Sun M. , Zhao G. , Pullerits T.
Published: April 2008

Stimulated by the recent experimental report of optical properties of charged oligofluorenes [S. Fratiloiu et al., J. Phys. Chem. B 110, 5984–5993 (2006)], we have used time‐dependent density functional theory (TD‐DFT) to study the electronic structure of neutral and charged ter‐fluorene with and without keto‐defect. We have characterized the excited states by site‐ and space‐based representations of the density matrix. For the defectless neutral species we found typical excitons, while the first excited states of the corresponding charged species represent long‐range oscillations of the electron or hole along the whole oligomer. For the neutral ketonized ter‐fluorene we found trapping of the excited electron. Similarly, the unpaired electron of the anion ground state is trapped. The excited state properties of the cation, however, are insensitive to the keto‐defect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polariton relaxation after resonant pumping at the upper polariton branch under doubly‐resonant Raman scattering conditions
Authors: Martín M. D. , Ballarini D. , Amo A. , Viña L. , André R.
Published: April 2008

We have investigated the influence of polariton–phonon interaction on the relaxation of microcavity polaritons towards the bottom of the lower polariton branch (LPB). We have varied either the energy difference between the two polariton branches at K ∼ 0 (negative detuning) or the Rabi splitting (zero detuning), adjusting them to coincide with the energy of a LO‐phonon. We have observed a sub‐linear/super‐linear increase of the LPB emission with pump power for negative/zero detuning, respectively. These different power dependencies can be explained by the combined effect of the different polariton–phonon scattering efficiency, which is minimum/maximum for large negative/zero detunings, a competition between several relaxation mechanisms and the different coupling to the excitonic reservoir of large‐K LPB states. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface electronic properties of n‐ and p‐type InGaN alloys
Authors: King P. D. C. , Veal T. D. , Lu Hai , Jefferson P. H. , Hatfield S. A. , Schaff W. J. , McConville C. F.
Published: April 2008

X‐ray photoemission spectroscopy is utilised to determine the variation in surface Fermi level pinning across the composition range of n‐ and p‐type c ‐plane Inx Ga1–x N alloys. The pinning relative to the charge neutrality level is used to explain a change in band bending direction causing a transition from surface electron accumulation (In‐rich) to depletion (Ga‐rich) at x ≈ 0.43 for n‐type alloys and a transition from surface inversion to hole depletion at x ≈ 0.59 for p‐type alloys where downward band bending occurs across the composition range. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plasma‐assisted MBE growth of (11$ \bar 2 $2)‐oriented GaN/AlN quantum wells on m‐sapphire
Authors: Lahourcade L. , Renard J. , Kandaswamy P. K. , Gayral B. , Monroy E.
Published: April 2008

We report on the plasma‐assisted molecular‐beam epitaxy growth of two‐dimensional (11$ \bar 2 $2)‐oriented AlN, GaN and GaN/AlN multiple quantum well (MQW) structures on (1$ \bar 1 $00) m ‐plane sapphire. Moderate N‐rich conditions enable to synthesize AlN(11$ \bar 2 $2) directly on m ‐sapphire, with inplane epitaxial relationships [11$ \bar 2 $$ \bar 3 $]AlN || [0001]sapphire and [1$ \bar 1 $00]AlN || [11$ \bar 2 $2]sapphire. In the case of GaN a Ga‐excess of one monolayer is necessary to achieve two‐dimensional growth of GaN(11$ \bar 2 $2). Applying the adequate growth conditions, we demonstrate the synthesis of (11$ \bar 2 $2)‐oriented GaN/AlN MQW structures. The reduction of the luminescence red shift and of the luminescence decay time compared to standard polar structures confirms the quantum confined Stark effect attenuation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Direct optical measurement of hot‐phonons in active AlGaN/GaN devices
Authors: Pomeroy J. W. , Kuball M. , Uren M. J. , Martin T.
Published: April 2008

We demonstrate the direct detection of hot‐phonons in the channel of active AlGaN/GaN HFETs by combining anti‐Stokes Raman scattering with conventional Raman thermography. Hot‐phonon temperatures were found to be consistent with hot‐electron temperatures determined using electroluminescence measurements. Temperatures reach as high as 1000 K for 30 V source–drain biases. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Band structure and effective mass of InN under pressure
Authors: Gorczyca I. , Dmowski L. , Plesiewicz J. , Suski T. , Christensen N. E. , Svane A. , Gallinat C. S. , Koblmueller G. , Speck J. S.
Published: April 2008

Calculations of the electronic band structure and effective mass of InN are performed within the density functional theory by means of the linear muffin‐tin‐orbital method. The results show a pronounced nonparabolicity of the conduction band. Calculated variations of the highest occupied conduction band energy and electron effective mass with free electron concentration are presented and compared to available experimental data. Pressure effects are studied. Both the fundamental band gap and the electron effective mass increase with hydrostatic pressure, but due to the nonparabolic character of the conduction band of InN the pressure coefficient of the effective mass decreases with electron concentration. Experimental verification of this behavior has been performed on three n‐type samples of InN with different electron concentrations. The measurements and calculations agree in the description of the dependence of effective mass and its pressure coefficient on electron concentration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Free‐standing zinc‐blende (cubic) GaN substrates grown by a molecular beam epitaxy process
Authors: Foxon C. T. , Novikov S. V. , Stanton N. M. , Campion R. P. , Kent A. J.
Published: April 2008

In this paper bulk, free‐standing, zinc‐blende (cubic) GaN wafers grown by plasma‐assisted molecular beam epitaxy (PA‐MBE) are described. GaN layers of up to 60 microns in thickness have been grown. Characterisation measurements confirm the cubic nature of the GaN crystals and show that the fraction of hexagonal material present is not more than ∼10%. Cubic (001)GaN does not exhibit the spontaneous and piezoelectric polarization effects associated with (0001) c‐axis wurtzite GaN. Free standing GaN wafers grown by PA‐MBE make ideal lattice‐matched substrates for the growth of cubic GaN‐based structures for optoelectronic devices, and high power and high frequency electronic applications. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unintentional doping in GaN assessed by scanning capacitance microscopy
Authors: Sumner J. , Bakshi S. Das , Oliver R. A. , Kappers M. J. , Humphreys C. J.
Published: April 2008

Using scanning capacitance microscopy (SCM) we observe a layer of unintentional n‐type conductivity in GaN/sapphire epilayers in a region adjacent to the GaN/sapphire interface. It is shown to have a carrier concentration of (1.66 ± 0.08) × 1018 cm–3. Secondary ion mass spectroscopy (SIMS) data from a similar sample suggests that the n‐type conductivity in this region results from unintentional oxygen incorporation. Various doped regions are also observed in epitaxial lateral over‐growth (ELOG) samples. GaN initially grows through a SiNx mask forming faceted stripes, which exhibit unintended n‐type conductivity. Magnesium is used to enhance stripe coalescence, resulting in p‐type regions. The top layer, grown following coalescence, appears non‐conducting. The different electron concentrations found within the ELOG cross‐section could correspond to the different facets formed during growth which may indicate that the changes in carrier concentration reflect the rate of impurity incorporation on each facet. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiple carrier transport in N‐face indium nitride
Authors: Fehlberg Tamara B. , Koblmüller Gregor , Umana‐Membreno Gilberto A. , Gallinat Chad S. , Nener Brett D. , Speck James S. , Parish Giacinta
Published: April 2008

We present temperature (20–300 K) dependent multi‐carrier measurements of electron species in N‐face indium nitride. N‐face InN samples were grown to different thicknesses (500–2000 nm) via plasma‐assisted molecular beam epitaxy on C‐face SiC substrates. Surface and bulk electron transport properties were extracted using a quantitative mobility spectrum analysis. Mobility of both bulk and surface electron species increase with film thickness. The temperature dependence of the mobility of both species differs to that of In‐polar samples studied previously, while the mobility of surface electrons is more than twice that of In‐polar samples with only a slight corresponding reduction in sheet concentration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular dynamics and first‐principles computations of Ga adlayers on GaN(0001)
Authors: Rinehimer J. A. , Widom M. , Northrup J. E. , Feenstra R. M.
Published: April 2008

Structural models for Ga adlayer(s) on GaN(0001) are investigated using both molecular dynamics and first‐principles computations. An energetically favourable model is deduced that is consistent with observed low‐energy electron diffraction data. The model contains regions of uniaxial contraction of the topmost Ga adlayer on the surface (rather than uniform biaxial contraction, as in previous models), multiple domains of which form a hexagonal arrangement on the surface. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)