bluuebunny/crossref_metadata_2025 huggingface dataset:
Global adaptive learning control of robotic manipulators by output error feedback
Authors: Liuzzo Stefano , Tomei Patrizio
Published: November 2008

This paper addresses the problem of designing a global, output error feedback based, adaptive learning control for robotic manipulators with revolute joints and uncertain dynamics. The reference signals to be tracked are assumed to be smooth and periodic with known period. By developing in Fourier series expansion the input reference signals of every joint, an adaptive, output error feedback, learning control is designed, which ‘learns’ the input reference signals by identifying their Fourier coefficients: global asymptotic and local exponential stability of the tracking error dynamics are obtained when the Fourier series expansion of each input reference signal is finite, while arbitrary small tracking errors are achieved otherwise. The resulting control is not model based and depends only on the period of the reference signals and on some constant bounds on the robot dynamics. Copyright © 2008 John Wiley & Sons, Ltd.
On trajectory‐dependent direct adaptive control for a class of uncertain linear discrete‐time systems
Authors: Cheng Chi‐Cheng , Fu Simon Hsu‐Sheng
Published: November 2008

In this paper, we develop a direct adaptive control framework for a class of linear discrete‐time uncertain multi‐input–multi‐output (MIMO) systems with exogenous bounded disturbances. The proposed adaptive controller guarantees adaptive stabilization, while the controller does not require the knowledge of system uncertainties. In addition, the framework is Lyapunov based with trajectory‐dependent hypothesis and the adaptive laws can be characterized by Kronecker calculus. Two numerical examples are provided to demonstrate the efficacy of the framework. Copyright © 2008 John Wiley & Sons, Ltd.
Polarity Effects of Polymer Gate Electrets on Non‐Volatile Organic Field‐Effect Transistor Memory
Authors: Baeg Kang‐Jun , Noh Yong‐Young , Ghim Jieun , Lim Bogyu , Kim Dong‐Yu
Published: November 2008

Organic non‐volatile memory (ONVM) based on pentacene field‐effect transistors (FETs) has been fabricated using various chargeable thin polymer gate dielectrics—termed electrets—onto silicon oxide insulating layers. The overall transfer curve of organic FETs is significantly shifted in both positive and negative directions and the shifts in threshold voltage (VTh) can be systemically and reversibly controlled via relatively brief application of the appropriate external gate bias. The shifted transfer curve is stable for a relatively long time—more than 105 s. However, this significant reversible shift in VTh is evident only in OFETs with non‐polar and hydrophobic polymer electret layers. Moreover, the magnitude of the memory window in this device is inversely proportional to the hydrophilicity (determined from the water contact angle) and dielectric polarity (determined from the dielectric constant), respectively. Memory behaviors of ONVM originate from charge storage in polymer gate electret layers. Therefore, the small shifts in VTh in ONVM with hydrophilic and polar polymers may be due to very rapid dissipation of transferred charges through the conductive channels which form from dipoles, residual moisture, or ions in the polymer electret layers. It is verified that the surface or bulk conductivities of polymer gate electret layers played a critical role in determining the non‐volatile memory properties.
Cadmium(II) (8‐Hydroxyquinoline) Chloride Nanowires: Synthesis, Characterization and Glucose‐Sensing Application
Authors: Pan Hongcheng , Lin Hongyu , Shen Qingming , Zhu Jun‐Jie
Published: November 2008

Luminescent cadmium(II) (8‐hydroxyquinoline) chloride (CdqCl) complex nanowires are synthesized via a sonochemical solution route. The results of X‐ray photoelectron spectroscopy, energy dispersive X‐ray analysis, infrared spectroscopy, elemental analysis (EA), and atomic absorption spectroscopy demonstrate that the chemical composition of the product is Cd(C9H6NO)Cl. Transmission electron microscopy and scanning electron microscopy images show that the CdqCl product is wire‐like in structure, with a diameter of approximately 50 nm and an approximate length of 2–4 µm. The morphology and composition of the product can be transformed from Cdq2 micrometer‐scaled flakes to CdqCl nanowires by increasing the ratio of CdCl2/q. A new fluorescent sensing strategy for detecting H2O2 and glucose is developed and is based on the combination of the luminescent nanowires and the biocatalytic growth of Au nanoparticles. The quenching effects of Au nanoparticles and ${\rm AuCl}_4^ - $ on the fluorescence of CdqCl nanowires are investigated. The dominant factor for the fluorescence quenching of CdqCl nanowires is that the Stern–Volmer quenching constant of Au nanoparticles is larger than that of ${\rm AuCl}_4^ - $.
A Triphenylamine Dye Model for the Study of Intramolecular Energy Transfer and Charge Transfer in Dye‐Sensitized Solar Cells
Authors: Tian Haining , Yang Xichuan , Pan Jingxi , Chen Ruikui , Liu Ming , Zhang Qingyu , Hagfeldt Anders , Sun Licheng
Published: November 2008

A novel dye (2TPA‐R), containing two triphenylamine (TPA) units connected by a vinyl group and rhodanine‐3‐acetic acid as the electron acceptor, is designed and synthesized successfully to reveal the working principles of organic dye in dye‐sensitized solar cells (DSSCs). 2TPA and TPA‐R, which consist of two TPA units connected by vinyl and a TPA unit linked with rhodanine‐3‐acetic acid, respectively, are also synthesized as references to study the intramolecular energy transfer (EnT) and charge transfer (ICT) processes of 2TPA‐R in CH2Cl2 solution and on a TiO2 surface. The results suggest that the intramolecular EnT and ICT processes show a positive effect on the performance of DSSCs. However, the flexible structure and less‐adsorbed amount of dye on TiO2 may make it difficult to improve the efficiency of DSSCs. This study on intramolecular EnT and ICT processes acts as a guide for the design and synthesis of efficient organic dyes in the future.
Towards Self‐Powered Nanosystems: From Nanogenerators to Nanopiezotronics
Authors: Wang Zhong Lin
Published: November 2008

Developing wireless nanodevices and nanosystems are of critical importance for sensing, medical science, defense technology, and even personal electronics. It is highly desirable for wireless devices and even required for implanted biomedical devices that they be self‐powered without use of a battery. It is essential to explore innovative nanotechnologies for converting mechanical energy (such as body movement, muscle stretching), vibrational energy (such as acoustic or ultrasonic waves), and hydraulic energy (such as body fluid flow) into electrical energy, which will be used to power nanodevices without a battery. This is a key step towards self‐powered nanosystems. We have demonstrated an innovative approach for converting mechanical energy into electrical energy by piezoelectric zinc oxide nanowire (NW) arrays. The operation mechanism of the electric generator relies on the unique coupling of the piezoelectric and semiconducting properties of ZnO as well as the gating effect of the Schottky barrier formed between the metal tip and the NW. Based on this mechanism, we have recently developed a DC nanogenerator (NG) driven by the ultrasonic wave in a biofluid and a textile‐fiber‐based NG for harvesting low‐frequency mechanical energy. Furthermore, a new field, “nanopiezotronics”, has been developed, which uses coupled piezoelectric–semiconducting properties for fabricating novel and unique electronic devices and components. This Feature Article gives a systematic description of the fundamental mechanism of the NG, its rationally innovative design for high output power, and the new electronics that can be built based on a piezoelectric‐driven semiconducting process. A perspective will be given about the future impact of the technologies.
Dramatic Morphology Control in the Fabrication of Porous Polymer Films
Authors: Connal Luke A. , Vestberg Robert , Hawker Craig J. , Qiao Greg G.
Published: November 2008

Highly ordered, porous honeycomb films are prepared by the breath‐figure (BF) technique using dendron‐functionalized star polymers as precursors. By changing the nature of the dendritic end groups, dramatically different porous morphologies can be produced. Three series of star polymers are prepared with both the size of the 2,2‐bis(methoxy)propionic acid (bis‐MPA)‐based dendron end group and the dendron functionality being varied. Star polymers end‐functionalized with acetonide‐protected dendrons (generations 1 to 4) are initially prepared and the acetonide groups subsequently deprotected to yield hydroxyl‐functionalized star polymers. Modification of these hydroxyl groups with pentadecafluorooctanoyl chloride yields a third series of functionalized star polymers. The resulting star polymers have surface groups with very different polarity and by utilizing these star polymers to form honeycomb films by the BF technique, the morphology produced is dramatically different. The star polymers with amphiphilic character afford interconnected porous morphologies with multiple layers of pores. The star polymers with pentadecafluorooctanoyl end groups show highly ordered monolayers of pores with extremely thin walls and represent a new porous morphology that has previously not been reported. The ability to prepare libraries of different dendronized star polymers has given further insights into the BF technique and allows the final porous morphology to be controllably tuned utilizing the functional chain ends and generation number of the dendronized star polymers.
Organic Light‐Emitting Diodes with Field‐Effect‐Assisted Electron Transport Based on α‐bi;,ω‐bi;‐Diperfluorohexyl‐quaterthiophene
Authors: Schols Sarah , McClatchey Christina , Rolin Cédric , Bode Dieter , Genoe Jan , Heremans Paul , Facchetti Antonio
Published: November 2008

Materials commonly used in the carrier transport layers of organic light‐emitting diodes, where transport occurs through the bulk, are in general very different from materials used in organic field‐effect transistors, where transport takes place in a very thin accumulation channel. In this paper, the use of a high‐performance electron‐conducting field‐effect transistor material, diperfluorohexyl‐substituted quaterthiophene (DFH‐4T), as the electron‐transporting material in an organic light‐emitting diode structure is investigated. The organic light‐emitting diode has an electron accumulation layer in DFH‐4T at the organic hetero‐interface with the host of the light‐emitting layer, tris(8‐hydroxyquinoline) aluminum (Alq3). This electron accumulation layer is used to transport electrons and inject them into the active emissive host‐guest layer. By optimizing the growth conditions of DFH‐4T for electron transport at the organic hetero‐interface, high electron current densities of 750 A cm−2 are achieved in this innovative light‐emitting structure.
On the Role of Bathocuproine in Organic Photovoltaic Cells
Authors: Gommans Hans , Verreet Bregt , Rand Barry P. , Muller Robert , Poortmans Jef , Heremans Paul , Genoe Jan
Published: November 2008

The effect of bathocuproine (BCP) on the optical and electrical properties of organic planar heterojunction photovoltaic cells is quantified by current–voltage characterization under 1 sun AM 1.5D simulated solar illumination and spectral response at short‐circuit conditions. By inserting a 10 nm BCP layer in an indium tin oxide (ITO)/subphthalocyanine (SubPc)/buckminsterfullerene (C60)/BCP/Al thin‐film structure, an increase in power‐conversion efficiency from 0.05 to 3.0% is observed, mostly reflected in the enhanced open‐circuit voltage up to 920 mV. Furthermore, the incorporation of a 10‐nm BCP layer in an ITO/C60/BCP/Al structure leads to an increase in built‐in potential from 250 to 850 mV, as demonstrated by electroabsorption. It is argued that BCP passivates C60 such that a 10‐nm layer provides a sufficient buffer layer that prohibits Al contacting the C60 where it would otherwise create donor states.
Prolinamides versus Prolinethioamides as Recyclable Catalysts in the Enantioselective Solvent‐Free Inter‐ and Intramolecular Aldol Reactions
Authors: Almaşi Diana , Alonso Diego A. , Nájera Carmen
Published: November 2008

A solvent‐free asymmetric and direct anti‐aldol reaction of aliphatic ketones with aromatic aldehydes catalyzed by recyclable L‐prolineamides and L‐prolinethioamides 3 is studied. The L‐prolinethioamide 3d (5 mol%), derived from L‐Pro and (R)‐1‐aminoindane, is the most efficient catalyst for this process affording the anti‐aldol adducts in high yields with excellent diastereo‐ and enantioselectivities (up to >98/2 dr, up to 98% ee) at 0 °C or room temperature. Prolinethioamide 3d is an effective organocatalyst for the first asymmetric, solvent‐free, intramolecular Hajos–Parrish–Eder–Sauer–Wiechert reaction with comparable or higher levels of enantioselectivity (up to 88% ee) to reported catalysts in organic solvents. Moreover, organocatalyst 3d can be easily recovered and reused by a simple acid/base extraction.
C3‐Symmetric Titanium(IV) Triphenolate Amino Complexes for a Fast and Effective Oxidation of Secondary Amines to Nitrones with Hydrogen Peroxide
Authors: Zonta Cristiano , Cazzola Elisa , Mba Miriam , Licini Giulia
Published: November 2008

The efficient catalytic oxidation of secondary amines to nitrones using hydrogen peroxide as primary oxidant is described. The titanium(IV) complex 2 bearing a C3‐symmetrical triphenolate amino ligand has proved to be an air‐ and water‐tolerant complex that efficiently catalyzes secondary amine oxidations at 60 °C without previous activation [catalyst loading as low as 0.01%, yields up to 99%, turnover numbers (TONs) up to 8000 and turnover frequencies (TOFs) up to 11000 h−1).
Convenient General Asymmetric Synthesis of Roche Ester Derivatives through Catalytic Asymmetric Hydrogenation: Steric and Electronic Effects of Ligands
Authors: Pautigny Cyrielle , Jeulin Séverine , Ayad Tahar , Zhang Zhaoguo , Genêt Jean‐Pierre , Ratovelomanana‐Vidal Virginie
Published: November 2008

An efficient and concise asymmetric hydrogenation of acrylate esters promoted by the cationic ruthenium monohydride complex [Ru(H)(η6‐cot)SYNPHOS]+BF4− is reported. A full investigation of the effects of catalyst precursors, solvents, temperature, hydrogen pressure, substrates as well as steric and electronic properties of ligands was carried out. The corresponding valuable Roche ester derivatives were obtained in good to excellent isolated yields and high enantioselectivities under mild conditions. The robustness and practicability of this highly enantioselective hydrogenation was demonstrated by the synthesis of the 3‐hydroxy‐2‐methylpropanoic acid tert‐butyl ester on a multigram scale, resulting in excellent yield and ee up to 94%.
A Selective and Practical Synthesis of Nitroolefins
Authors: Jovel Irina , Prateeptongkum Saisuree , Jackstell Ralf , Vogl Nadine , Weckbecker Christoph , Beller Matthias
Published: November 2008

A straightforward and general synthesis of nitroolefins from nitric oxide (NO) and olefins is presented. The direct nitration of aromatic olefins, allyl compounds, and acrylic acid derivatives proceeds smoothly at room temperature with high regioselectivity and good yields. The advantages of this novel procedure compared to established nitration procedures are demonstrated.
Ligand‐Free Iron/Copper Cocatalyzed Alkynylation Coupling Reactions
Authors: Mao Jincheng , Xie Guanlei , Wu Minyan , Guo Jun , Ji Shunjun
Published: November 2008

Ligand‐free iron/copper cocatalyzed cross‐coupling reactions of aryl halides with terminal alkynes were carried out to provide the corresponding coupling products in good yields (up to 99%). Noteworthy is that this low‐cost, effective and environmentally friendly protocol was the first to be employed in alkynylation couplings.
Robust Bayesian estimation of kinetics for the polymorphic transformation of L‐glutamic acid crystals
Authors: Hermanto Martin Wijaya , Kee Nicholas C. , Tan Reginald B. H. , Chiu Min‐Sen , Braatz Richard D.
Published: November 2008

Polymorphism, in which there exist different crystal forms for the same chemical compound, is an important phenomenon in pharmaceutical manufacturing. In this article, a kinetic model for the crystallization of L‐glutamic acid polymorphs is developed from experimental data. This model appears to be the first to include all of the transformation kinetic parameters including dependence on the temperature. The kinetic parameters are estimated by Bayesian inference from batch data collected from two in situ measurements: ATR‐FTIR spectroscopy is used to infer the solute concentration, and FBRM that provides crystal size information. Probability distributions of the estimated parameters in addition to their point estimates are obtained by Markov Chain Monte Carlo simulation. The kinetic model can be used to better understand the effects of operating conditions on crystal quality, and the probability distributions can be used to assess the accuracy of model predictions and incorporated into robust control strategies for polymorphic crystallization. © 2008 American Institute of Chemical Engineers AIChE J, 2008
The structural organization in aqueous solutions of ionic liquids
Authors: Zhu Xiao , Wang Yong , Li Haoran
Published: November 2008

The 1H NMR combined with the local composition (LC) model has been employed to investigate the structural organization of two aqueous solutions of ionic liquids (ILs), namely 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EmimBF4) and n‐butylammonium nitrate (N4NO3). The correlation of chemical shifts using the LC model shows that the self‐association of IL plays the leading role, and water prefers to interact with IL rather than self‐association in IL‐rich region. Instead the network of water molecules is established in water‐rich region, because the self‐association of water predominates. Furthermore, the difference between the local and the bulk composition presents the turnover at x(IL) (mole fraction of IL) close to 0.6 for EmimBF4/water, which is in accordance with the change of excess function. Accordingly, it could be presumed that the excess properties for N4NO3/water system should behave turnover at x(IL) ≈ 0.55 since the local and the bulk exhibit maximal difference at this composition. © 2008 American Institute of Chemical Engineers AIChE J, 2009
Swelling kinetics of linseed oil‐based polymers
Authors: Sharma Vinay , Banait J. S. , Kundu P. P.
Published: November 2008

Kinetics of swelling and sorption behavior of copolymers (based on linseed oil, styrene, divinylbenzene, and acrylic acid via cationic and thermal polymerization) is studied in tetrahydrofuran (THF) at different temperatures. The values of n in the transport equation are found to be below 0.4, showing non‐Fickian or pseudo‐Fickian transport in the polymers. The dependence of diffusion coefficient on the composition and temperature has also been studied for the linseed oil‐based polymers. The diffusion coefficient in cationic samples decreases with an increase in the oil contents in the samples. In case of thermal samples, the diffusion coefficient first increases up to 30% oil contents and then decreases. The diffusion coefficient decreases with an increase in temperature for all of the linseed oil polymer samples. The sorption coefficient increases with an increase in the oil contents for all samples. The crosslink density (calculated from the THF swelling) ranges from 20.16 to 92.34 × 106 mol/cm3 for cationic samples and 20.62 to 86.01 × 106 mol/cm3 for thermal samples. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
TPA‐PPEs – New alternating donor copolymers for potential application in photovoltaic devices
Authors: Blankenburg Lars , Hager Martin D. , Sell Stephan , Sensfuss Steffi , Klemm Elisabeth
Published: November 2008

A series of phenyleneethynylene copolymers with triphenylamine units as hole‐transporting moieties (TPA‐PPEs) were synthesized by the palladium‐catalyzed cross‐coupling polycondensation of diethynyltriphenylamines and selected dihalogen comonomers, for instance substituted benzene, thiophene, benzothiadiazole, or anthracene. Incorporation of the electron‐rich amino group into the PPE backbone does not interrupt the main chain conjugation. Furthermore, it has a decreasing effect on the oxidation potential, thus makes these polymers interesting as hole‐injection/hole‐transporting materials. The chemical structure of the new alternating copolymers was confirmed by 1H and 13C NMR spectroscopy and elemental analysis and gel‐permeation chromatography (GPC; THF, Mn ≈ 15,000–30,000 g/mol) was conducted. Furthermore, their optical properties were investigated by UV/vis spectroscopy. The TPA‐PPEs exhibit absorption maxima at around 400 nm (π‐π*), except anthracene containing copolymer 3f (λmax = 514 nm in THF) and benzothiadiazole containing one 3g (λmax = 503 nm in THF). The TPA copolymers have oxidation potentials about 1.1 V (Ag/AgCl). They are good photoconducting materials (3a: IPhoto = 4 × 10−10 A at 425 nm (400 V), 3g: IPhoto = 1.3 × 10−11 A at λmax = 500 nm (20 V)) and show emission after excitation at around 450 nm (560 nm 3f). Their application in nonoptimized polymer solar cells (bulk heterojunction) led to power conversion efficiencies of around 1–1.8% after illumination with 100 mW/cm2 of AM1.5. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Improved mechanical properties of NR/EPDM blends by controlling the migration of curative and filler via reactive processing technique
Authors: Sahakaro Kannika , Pongpaiboon Chararat , Nakason Charoen
Published: November 2008

Simple blending of natural rubber/ethylene–propylene–diene rubber (NR/EPDM) generally results in inferior mechanical properties because of curative migration and their differences for filler affinity. In this work, the 70/30 and 50/50 NR/EPDM blends prepared by reactive processing techniques were investigated and compared with the simple, nonreactive blends. The reactive blend compounds were prepared by preheating EPDM, containing all curatives to a predetermined time related to their scorch time prior to blending with NR. For the 70/30 gum blends, four types of accelerators were studied: 2,2‐mercaptobenzothiazole (MBT), 2,2‐dithiobis‐ (benzothiazole) (MBTS), N‐cyclohexyl‐2‐benzothiazolesulfenamide (CBS), and N‐tert‐butyl‐2‐benzothiazolesulfenamide (TBBS). When compared with the simple blends, the reactive blends cured with CBS and MBTS showed a clearly improved tensile strength whereas the increase of tensile strength in the blends cured with TBBS and MBT was marginal. However, a dramatic improvement of ultimate tensile properties in the reactive 50/50 NR/EPDM blends cured with TBBS was observed when compared with the simple blend. For the N‐550‐filled blends at the blend ratios of 70/30 and 50/50, the reactive‐filled blends prepared under the optimized preheating times demonstrated superior tensile strength and elongation at break over the simple blends. The improved crosslink and/or filler distribution between the two rubber phases in the reactive blends accounts for such improvement in their mechanical properties. This is shown in the scanning electron micrographs of the tensile fractured surfaces of the reactive blends, which indicate a more homogeneous blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Mechanical and surface properties and hydrolytic stability of cycloaliphatic polyester‐based waterborne polyurethanes modified with fluoro oligomer
Authors: Hong Park Sang , Lee Su Kyoung , Choi Hee Young , Lee Eon Mi , Kim Eun Young , Lim Chung Hwan , Lee Dong Woon , Kim Byung Kyu
Published: November 2008

Polyurethane dispersions (PUDs) have been designed and synthesized based on different types of soft segments, namely, poly(2,4‐diethyl‐1,5‐pentamethylene adipate) glycol (PDPAD; $\overline {M_n }$ = 1000) and poly(2,4‐diethyl‐1,5‐pentamethylene‐1,4‐cyclohexane dicarboxylate) glycol (PDPCD; $\overline {M_n }$ = 1000), and were subsequently modified with fluoro oligomer (BA‐N fluoroalcohol). It was found that the PDPCD segments improved the hydrolytic stability, whereas the contact angle with water drop was significantly increased with the addition and increasing amount of Zonyl for PDPAD‐based PU and it was marginally increased with PDPCD‐based PU. In addition, the PDPCD provided PUD with enhanced mechanical properties compared with the PDPAD. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Cellulose/polypropylene composites: Influence of the molecular weight and concentration of oxidatively degraded and maleated polypropylene compatibilizers on tensile behavior
Authors: Miyazaki Kensuke , Moriya Kyosuke , Okazaki Noriyasu , Terano Minoru , Nakatani Hisayuki
Published: November 2008

To improve interactions between fibrous cellulose (FC) and polypropylene (PP), oxidatively degraded polypropylene (DgPP) and maleated polypropylene (MAPP) were studied as compatibilizers. Both compatibilizers had the same mechanism, using esterification between the OH group in FC and the reactive (γ‐lactone, acid, and maleic anhydride) groups in the compatibilizers. However, the adhesion style with the ester bond was considerably different because of the arrangements of the reactive groups. DgPP had reactive groups at the polymer chain end, and the tensile behavior of the FC/PP/DgPP composite exhibited comparatively ductile behavior. However, MAPP had inner reactive groups, and the tensile behavior of the FC/PP/MAPP composite was quite brittle. Observation of these fracture surfaces suggested that the adhesion performance of the interface between FC and PP was strongly influenced by the arrangements of the reactive group. In addition, the performance was influenced by the molecular weight of DgPP and by the content of maleic anhydride groups in MAPP. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation of comb‐type grafted hydrogels composed of polyacrylamide and chitosan and their use for DNA adsorption
Authors: Başer Burcu , Demirel Gökçen Birlik , Açık Leyla , Çaykara Tuncer
Published: November 2008

Comb‐type grafted hydrogels composed of polyacrylamide (PAAm) and chitosan (CT) were prepared and used for DNA adsorption. Instead of direct grafting of the acrylamide monomer onto the CT chain, semitelechelic PAAm with carboxylic acid end groups (PAAm–COOH) was synthesized by free‐radical polymerization with mercaptoacetic acid as the chain‐transfer agent, and it was grafted onto CT with amino groups. The synthesis of telechelic PAAm–COOH and the formation of comb‐type grafted hydrogels were confirmed by attenuated total reflectance/Fourier transform infrared spectroscopy and scanning electron microscopy measurements. The prepared comb‐type grafted hydrogels were used as sorbents in DNA adsorption experiments conducted at +4°C in a tris(hydroxymethyl)aminomethane/ethylenediaminetetraacetic acid solution of pH 7.4. DNA adsorption capacities as high as 2.0 × 103 μg of DNA/g of dry gel could be achieved by the comb‐type hydrogels with higher PAAm contents. This value was approximately 6 times higher than that of CT alone. In addition, the comb‐type hydrogels showed a high adsorption/desorption rate depending on the PAAm content in the hydrogel. As a result, these comb‐type hydrogels carrying higher amounts of DNA may be considered good candidates for achieving higher removal rates for anti‐DNA antibodies and for effective gene therapy systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Mixed stream channel morphologies: implications for fish community diversity
Authors: Cianfrani Christina M. , Sullivan S. Mažeika P. , Hession W. Cully , Watzin Mary C.
Published: November 2008

Stream classification systems are widely used in stream management and restoration. Whereas the principal morphological types of these classification systems are increasingly recognized for their ecological connections, the roles of intermediate and mixed morphologies are still poorly understood, yet may be biologically significant.

Twenty‐five stream reaches in north‐western Vermont were classified by channel morphology to determine whether fish community diversity differed among pool‐riffle, mixed (i.e. pool‐riffle/cascade, pool‐riffle/other) and forced pool‐riffle stream morphological groups. Stream reach surveys included cross‐sectional surveys, longitudinal profiles, bed substrate characterization, and fish surveys.

Three fish community diversity measures were calculated: (1) species richness (S); (2) Shannon–Weaver Index (H′); and (3) Simpson's Index (1/D). Multivariate analysis of covariance (MANCOVA) followed by analysis of variance (ANOVA) were used to explore potential differences in fish diversity among stream morphological groups. Fish diversity was significantly different for all three community diversity measures (P⩽0.05), with pool‐riffle/cascade morphology consistently exhibiting the greatest fish diversity and forced pool‐riffle the lowest.

These results suggest that fish community diversity is significantly associated with distinct channel morphologies. Generally, pool‐riffle/cascade and pool‐riffle/other stream morphological groups supported habitats that fostered greater species diversity than more homogeneous and uniform pool‐riffle reaches. The observed patterns of diversity are likely to be the result of habitat patches created by variations in flow and other physical characteristics in reaches of mixed morphologies.

These results support fish sampling schemes that incorporate morphological heterogeneity, such as proportional‐distance designation. Sampling strategies that focus on homogeneous reaches may underestimate diversity, and misrepresent stream condition when fish community data are used in indices of biological integrity (IBIs). Reaches of mixed stream morphologies should be recognized as areas of biological importance in stream and catchment management and in conservation efforts.

Copyright © 2008 John Wiley & Sons, Ltd.
Restoration effort, habitat mosaics, and macroinvertebrates — does channel form determine community composition?
Authors: Jähnig Sonja C. , Lorenz Armin W. , Hering Daniel
Published: November 2008

In certain lower mountainous regions of Germany multiple‐channel streams constitute the reference condition for stream restoration and conservation efforts. An increasing number of restoration projects re‐establish such stream sections, but their impact on macroinvertebrate communities remains vague and needs further elaboration.

Seven pairs of single‐ and multiple‐channel sections of mountain rivers were compared in terms of hydromorphology and macroinvertebrate communities. The stream sections were characterized by 16 hydromorphological metrics at various scales, e.g. shore length, channel feature or substrate diversity, flow variability and substrate coverage. Macroinvertebrate data were obtained from 140 substrate‐specific samples, which were combined to form representative communities for each section. Community data were subject to similarity and cluster analyses. Thirty‐five metrics were calculated with the taxa lists, including number of taxa, abundance, feeding type, habitat and current preferences.

Bray–Curtis similarity was very high (69–77%) between communities of single‐ and multiple‐channel sections. Biological metrics were correlated with hydromorphological parameters. Mean Spearman rank r was 0.59 (absolute values). The biological metrics percentage of the community preferring submerged vegetation, being grazers and scrapers or active filter feeders, percentage of epipotamal preference and the percentage of current preference (rheo‐ to limnophil and rheobiont) were significantly correlated with hydromorphological parameters.

Differences between stream sections can be attributed to single taxa occurring only in either the single‐ or multiple‐channel sections. These exclusive taxa were mainly found on organic substrates such as living parts of terrestrial plants, large wood, coarse particulate organic matter (CPOM) and mud. Reasons for high similarity of macroinvertebrate communities from single‐ or multiple‐channel sections are discussed, including the influence of large‐scale catchment pressures, length of restored sections and lack of potential re‐colonizers.

Copyright © 2008 John Wiley & Sons, Ltd.
Willow (Salix spp.) and aspen (Populus tremula) regrowth after felling by the Eurasian beaver (Castor fiber): implications for riparian woodland conservation in Scotland
Authors: Jones Kevin , Gilvear David , Willby Nigel , Gaywood Martin
Published: November 2008

A proposed trial reintroduction of the Eurasian beaver (Castor fiber L.) to Scotland has recently been approved (May 2008). A previous proposal was turned down by the licensing authority, partly over the perceived risks to woodland within a Special Area of Conservation.

This paper presents data on two years of willow (Salix spp.) and aspen (Populus tremula L.) regrowth following tree felling by captive beavers within two large semi‐natural enclosures in eastern Scotland. Both willow and aspen are highly preferred by beavers.

Regrowth of willow stems was quantified from cut stumps, felled logs and partially severed (‘incompletely felled’) trees, and compared with growth of stems in the canopies of untouched willows.

Maximum annual regrowth was observed in incompletely felled trees, followed by cut stumps and then unfelled control trees. Mean regrowth rates were ca 18 m regrowth per metre of measured tree section per year in incompletely felled trees. This was approximately 12 times more annual regrowth than that observed in unfelled trees, despite apparently selective browsing of the regrowth of incompletely felled trees by roe deer.

Although incompletely felled willows represent a relatively small component of felling activity (9% of all felled willow), they contribute disproportionately to the biomass of beaver‐engineered riparian woodlands, creating a more multi‐layered habitat structure.

Willow regrowth in inundated areas was avoided by deer, and harvesting of regrowth by beavers was rare.

Significant regrowth from 11 stumps of aspen in 2 years post‐felling occurred by suckering, with 85 suckers of mean height 2.1 m being recorded, all of which were subsequently avoided by browsing deer and beavers.

These data suggest that rapid regeneration of willow and aspen will occur in riparian woodlands in the event of major felling activity by Eurasian beaver, even in the presence of low to moderate levels of roe deer browsing, and that the conservation status of both these trees or the wider habitats that they form would not be threatened by a well planned and managed reintroduction of beavers to Scotland.

Copyright © 2008 John Wiley & Sons, Ltd.
Harbour seal movements and haul‐out patterns: implications for monitoring and management
Authors: Cunningham Louise , Baxter John M. , Boyd Ian L. , Duck Callan D. , Lonergan Mike , Moss Simon E. , McConnell Bernie
Published: November 2008

Compliance with conservation legislation requires knowledge on the behaviour, abundance and distribution of protected species. Seal life history is characterized by a combination of marine foraging and a requirement to haul out on a solid substrate for reproduction and moulting. Thus understanding the use of haul out sites, where seals are counted, as well as their at‐sea movements is crucial for designing effective monitoring and management plans.

This study used satellite transmitters deployed on 24 harbour seals in western Scotland to examine movements and haul‐out patterns.

The proportion of time harbour seals spent hauled out (daily means of between 11 and 27%) varied spatially, temporally and according to sex. The mean haul‐out duration was 5 h, with a maximum of over 24 h.

Patterns of movement were observed at two geographical scales; while some seals travelled over 100 km, 50% of trips were within 25 km of a haul‐out site. These patterns are important for the identification of a marine component to designated protected areas for the species.

On average seals returned to the haul‐out sites they last used during 40% of trips, indicating a degree of site fidelity, though there was wide variation between different haul‐out sites (range 0% to >75%).

Low fidelity haul‐out sites could form a network of land‐based protected areas, while high fidelity sites might form appropriate management units.

Copyright © 2008 John Wiley & Sons, Ltd.
Some comments on “A Proposal for a Dynamic h‐Type Index” by Rousseau and Ye
Authors: Burrell Quentin L.
Published: November 2008

Caution is urged over the adoption of dynamic h‐type indexes as advocated by Rousseau and Ye (2008). It is shown that the dynamics are critically dependent upon model assumptions and that practical interpretation might therefore be problematic. However, interesting questions regarding the interrelations between various h‐type indexes are raised.
Simulating growth of the h‐index
Authors: Guns Raf , Rousseau Ronald
Published: November 2008

Temporal growth of the h‐index in a diachronous cumulative time series is predicted to be linear by Hirsch (2005), whereas other models predict a concave increase. Actual data generally yield a linear growth or S‐shaped growth. We study the h‐index's growth in computer simulations of the publication‐citation process. In most simulations the h‐index grows linearly in time. Only occasionally does an S‐shape occur, while in our simulations a concave increase is very rare. The latter is often signalled by the occurrence of plateaus—periods of h‐index stagnation. Several parameters and their influence on the h‐index's growth are determined and discussed.
A method for extension of generative topographic mapping for fuzzy clustering
Authors: Bose Indranil , Chen Xi
Published: November 2008

In this paper, a new method for fuzzy clustering is proposed that combines generative topographic mapping (GTM) and Fuzzy c‐means (FCM) clustering. GTM is used to generate latent variables and their posterior probabilities. These two provide the distribution of the input data in the latent space. FCM determines the seeds of clusters, as well as the resultant clusters and the corresponding membership functions of the input data, based on the latent variables obtained from GTM. Experiments are conducted to compare the results obtained using FCM and the Gustafson‐Kessel (GK) algorithm with the proposed method in terms of four cluster‐validity indexes. Using simulated and benchmark data sets, it is observed that the hybrid method (GTMFCM) performs better than FCM and GK algorithms in terms of these indexes. It is also found that the superiority of GTMFCM over FCM and GK algorithms becomes more pronounced with the increase in the dimensionality of the input data set.
Birth Defects Cluster Study: A national approach to birth defects cluster investigations
Authors: Kucik James E. , Bitsko Rebecca H. , Williams Laura , Lazarus Carrie , Jarman Dwayne W. , Correa Adolfo
Published: November 2008

BACKGROUND: Investigations of clusters of birth defects have been challenging endeavors that have had only modest success identifying causes or risk factors. Some of the challenges to individual cluster investigations have been small sample size and limited data collection. We describe a novel approach for investigating and analyzing pooled information from a series of birth defects cluster investigations. METHODS: The Birth Defects Cluster Study uses a case‐control study design with standardized methods, including a case definition, control selection, data collection methods, and data collected (e.g., maternal interviews, blood samples, and environmental samples). Analyses of pooled data from several clusters of the same defect are conducted for specific hypotheses once a sufficient sample size has been achieved. The feasibility of conducting individual birth defect investigations was evaluated on a cluster of gastroschisis. RESULTS: The pilot investigation of a cluster of gastroschisis demonstrated success in recruiting participants and in collecting data and specimens for eventual inclusion in a pooled analysis. CONCLUSIONS: The Birth Defects Cluster Study offers a unique and effective approach to cluster investigations that improves the likelihood of identifying genetic and environmental causes of birth defects and provides a model for cluster investigations of other noninfectious health outcomes. Birth Defects Research (Part A), 2008. Published 2008 Wiley‐Liss, Inc.
Maternal periconceptional exposure to cigarette smoking and alcohol and esophageal atresia ± tracheo‐esophageal fistula
Authors: Wong‐Gibbons Donna L. , Romitti Paul A. , Sun Lixian , Moore Cynthia A. , Reefhuis Jennita , Bell Erin M. , Olshan Andrew F.
Published: November 2008

BACKGROUND: Esophageal atresia (EA) is a moderately frequent birth defect that often occurs with tracheo‐esophageal fistula (TEF). Etiologic studies for EA±TEF have produced inconsistent results. METHODS: This study used data from the National Birth Defects Prevention Study (NBDPS) to examine the association between maternal periconceptional exposure to cigarette smoking and alcohol and EA±TEF. Cases of EA±TEF and unaffected controls with an estimated date of delivery from October 1997 through December 2003 were identified, and telephone interview reports for smoking and alcohol exposure were obtained from birth mothers of 334 cases and 4,967 controls. Odds ratios (OR)s and 95% confidence intervals (CI)s, adjusted for several covariates, were calculated to assess associations. RESULTS: ORs were near unity for all EA±TEF cases combined and any periconceptional exposure to cigarette smoking (OR = 1.1; CI = 0.8,1.6) or alcohol (OR = 1.2; CI = 0.8,1.8). For cigarette smoking, some elevated ORs were found but varied by type of smoking exposure. No consistent patterns were identified for number of cigarettes smoked per day. For alcohol, ORs were weak to moderately elevated with increasing number of drinks consumed and for binge drinkers compared to non‐binge drinkers. ORs were further elevated among mothers who reported active+passive exposure to cigarette smoking and alcohol (OR = 2.5; CI = 1.1,5.6). For both exposures, ORs were higher for cases with additional major defects compared to isolated cases. CONCLUSIONS: These results, based on one of the largest published samples of EA±TEF cases, suggest a role for these exposures in the etiology of EA±TEF, although further study is needed to replicate the observed associations. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.
Performance and population analysis of a non‐sterile trickle bed reactor inoculated with Caldicellulosiruptor saccharolyticus, a thermophilic hydrogen producer
Authors: van Groenestijn J.W. , Geelhoed J.S. , Goorissen H.P. , Meesters K.P.M. , Stams A.J.M. , Claassen P.A.M.
Published: November 2008

Non‐axenic operation of a 400 L trickle bed reactor inoculated with the thermophile Caldicellulosiruptor saccharolyticus, yielded 2.8 mol H2/mol hexose converted. The reactor was fed with a complex medium with sucrose as the main substrate, continuously flushed with nitrogen gas, and operated at 73°C. The volumetric productivity was 22 mmol H2/(L filterbed h). Acetic acid and lactic acid were the main by‐products in the liquid phase. Production of lactic acid occurred when hydrogen partial pressure was elevated above 2% and during suboptimal fermentation conditions that also resulted in the presence of mono‐ and disaccharides in the effluent. Methane production was negligible. The microbial community was analyzed at two different time points during operation. Initially, other species related to members of the genera Thermoanaerobacterium and Caldicellulosiruptor were present in the reactor. However, these were out‐competed by C. saccharolyticus during a period when sucrose was completely used and no saccharides were discharged with the effluent. In general, the use of pure cultures in non‐sterile industrial applications is known to be less useful because of contamination. However, our results show that the applied fermentation conditions resulted in a culture of a single dominant organism with excellent hydrogen production characteristics. Biotechnol. Bioeng. 2009;102: 1361–1367. © 2008 Wiley Periodicals, Inc.
Elucidation of metabolism in hybridoma cells grown in fed‐batch culture by genome‐scale modeling
Authors: Selvarasu Suresh , Wong Victor V.T. , Karimi Iftekhar A. , Lee Dong‐Yup
Published: November 2008

Genome‐scale modeling of mouse hybridoma cells producing monoclonal antibodies (mAb) was performed to elucidate their physiological and metabolic states during fed‐batch cell culture. Initially, feed media nutrients were monitored to identify key components among carbon sources and amino acids with significant impact on the desired outcome, for example, cell growth and antibody production. The monitored profiles indicated rapid assimilation of glucose and glutamine during the exponential growth phase. Significant increase in mAb concentration was also observed when glutamine concentration was controlled at 0.5 mM as a feeding strategy. Based on the reconstructed genome‐scale metabolic network of mouse hybridoma cells and fed‐batch profiles, flux analysis was then implemented to investigate the cellular behavior and changes in internal fluxes during the cell culture. The simulated profile of the cell growth was consistent with experimentally measured specific growth rate. The in silico simulation results indicated (i) predominant utilization of glycolytic pathway for ATP production, (ii) importance of pyruvate node in metabolic shifting, and (iii) characteristic pattern in lactate to glucose ratio during the exponential phase. In future, experimental and in silico analyses can serve as a promising approach to identifying optimal feeding strategies and potential cell engineering targets as well as facilitate media optimization for the enhanced production of mAb or recombinant proteins in mammalian cells. Biotechnol. Bioeng. 2009;102: 1494–1504. © 2008 Wiley Periodicals, Inc.
Automated, scalable culture of human embryonic stem cells in feeder‐free conditions
Authors: Thomas Rob J. , Anderson David , Chandra Amit , Smith Nigel M. , Young Lorraine E. , Williams David , Denning Chris
Published: November 2008

Large‐scale manufacture of human embryonic stem cells (hESCs) is prerequisite to their widespread use in biomedical applications. However, current hESC culture strategies are labor‐intensive and employ highly variable processes, presenting challenges for scaled production and commercial development. Here we demonstrate that passaging of the hESC lines, HUES7, and NOTT1, with trypsin in feeder‐free conditions, is compatible with complete automation on the CompacT SelecT, a commercially available and industrially relevant robotic platform. Pluripotency was successfully retained, as evidenced by consistent proliferation during serial passage, expression of stem cell markers (OCT4, NANOG, TRA1‐81, and SSEA‐4), stable karyotype, and multi‐germlayer differentiation in vitro, including to pharmacologically responsive cardiomyocytes. Automation of hESC culture will expedite cell‐use in clinical, scientific, and industrial applications. Biotechnol. Bioeng. 2009;102: 1636–1644. © 2008 Wiley Periodicals, Inc.