bluuebunny/crossref_metadata_2025 huggingface dataset:
Biofunctionalization of Vertically Aligned Diamond Nanowires
Authors: Yang Nianjun , Uetsuka Hiroshi , Nebel Christoph E.
Published: February 2009

Vertically aligned diamond nanowires are biofunctionalized using aminophenyl linker molecules to bond nucleic acid molecules with a well‐defined nanometer‐sized spacing to the transducer. This novel DNA biosensor combines the outstanding electrochemical properties of diamond as a transducer with the controlled bonding of DNA molecules to the tips of nanowires by use of an electrochemical attachment scheme. Nucleic acid molecules are bonded in this way and dispersed to the transducer, giving rise to optimized hybridization kinetics of DNA. Negatively charged redox mediator molecules (Fe(CN)63−/4−) are applied for DNA‐hybridization sensing. Voltammetric detection of DNA hybridization by differential pulse voltammetry is performed with respect to its sensitivity and reproducibility. On a sensor area of 0.03 cm2, a detection limit of 2.0 pM is achieved. As for the chemical stability of the DNA bonding to the diamond nanowires, no degradation over 30 hybridization/denaturation cycles could be detected. By use of this dilute DNA arrangement, single‐base mismatch discrimination is achieved. Under the same conditions, smooth diamond modified with phenyl is not suitable for amperometric DNA sensing.
Aliovalent Substitutions in Olivine Lithium Iron Phosphate and Impact on Structure and Properties
Authors: Meethong Nonglak , Kao Yu‐Hua , Speakman Scott A. , Chiang Yet‐Ming
Published: February 2009

Lithium transition metal phosphate olivines are enabling a new generation of high power, thermally stable, long‐life rechargeable lithium batteries that may prove instrumental in the worldwide effort to develop cleaner and more sustainable energy. Nanoscale (<100 nm) derivatives of the olivine family LiMPO4 (M = Fe, Mn, Co, Ni) are being adopted in applications ranging in size scale from hybrid and plug‐in hybrid electric vehicles to utilities‐scale power regulation. Following the previous paradigm set with intercalation oxides, most studies have focused on the pure ordered compounds and isovalent substitutions. In contrast, even the possibility for, and role of, aliovalent doping has been widely debated. Here, critical tests of plausible defect compensation mechanisms using compositions designed to accommodate Mg2+, Al3+, Zr4+, Nb5+ ions on the M1 and/or M2 sites of LiFePO4 with appropriate charge‐compensating defects are carried out, and conclusive crystallographic evidence for lattice doping, e.g., up to at least 12 atomic percent added Zr, is obtained. Structural and electrochemical analyses show that doping can reduce the lithium miscibility gap, increase phase transformation kinetics during cycling, and expand Li diffusion channels in the structure. Aliovalent modifications may be effective for introducing controlled atomic disorder into the ordered olivine structure to improve battery performance.
Bifurcated Mechanical Behavior of Deformed Periodic Porous Solids
Authors: Singamaneni Srikanth , Bertoldi Katia , Chang Sehoon , Jang Ji‐Hyun , Young Seth L. , Thomas Edwin L. , Boyce Mary C. , Tsukruk Vladimir V.
Published: February 2009

The transformation of periodic microporous structures fabricated by interference lithography followed by their freezing below glass transition is described. Periodic porous microstructures subjected to internal compressive stresses can undergo sudden structural transformation at a critical strain. The pattern transformation of collapsed pores is caused by the stresses originated during the polymerization of acrylic acid (rubbery component) inside of cylindrical pores and the subsequent solvent evaporation in the organized microporous structure. By confining the polymerization of acrylic acid to localized porous areas complex microscopic periodic structures can be obtained. The control over the mechanical instabilities in periodic porous solids at a sub‐micron scale demonstrated here suggests the potential mechanical tunability of photonic, transport, adhesive, and phononic properties of such periodic porous solids.
Polyphenylene‐Based Materials: Control of the Electronic Function by Molecular and Supramolecular Complexity
Authors: Schmaltz Bruno , Weil Tanja , Müllen Klaus
Published: February 2009

Organic electronics is one of the hottest and most exciting research topics today. However, its performance still lags behind that of inorganic‐based electronics. This Progress Report demonstrates that by controlling the complexity of organic molecules at the molecular and at the supramolecular level as well as by choosing suitable processing techniques, the desired function for applications in electronics can be achieved. Our main focus is on polyphenylene‐based nanomaterials, versatile organic molecules that allow access to novel intricate materials. We emphasize the molecular complexity as well as the supramolecular organization and the interfacing of novel organic materials as key guidelines.
Formation of Network and Cellular Structures by Viscoelastic Phase Separation
Authors: Tanaka Hajime
Published: February 2009

Network (sponge) and cellular structures are often seen in various types of materials. Materials with such structures are generally characterized by light weight and high mechanical strength. The usefulness of such materials is highlighted, for example, by the remarkable material properties of bone tissue, which often has a highly porous structure. In artificial materials, plastic and metallic foams and breads have such structures. Here, we describe a physical principle for producing network and cellular structures using phase separation, and its potential applications to the morphological control of materials spanning from soft to hard matter.
Social facilitation of exploratory foraging behavior in capuchin monkeys (Cebus apella)
Authors: Dindo Marietta , Whiten Andrew , de Waal Frans B. M.
Published: February 2009

Much of the research on animal social learning focuses on complex cognitive functions such as imitation and emulation. When compelling evidence for such processes is not forthcoming, simpler processes are often assumed but rarely directly tested for. In this study we address the phenomenon of social facilitation, whereby the presence of a feeding conspecific is hypothesized to affect the motivation and behavior of the subject, elevating the likelihood of exploration and discovery in relation to the task at hand. Using a novel foraging task, sufficiently challenging that only just over half the subjects successfully gained food from it, we compared the performance of capuchin monkeys working either alone, or in a “social” condition where an actively feeding conspecific was in an adjacent chamber. Although similar numbers of subjects in these conditions were eventually successful during the 20 trials presented, the latency to successful solution of the task was over three times faster for monkeys in the social condition. The minority of monkeys that failed to learn (9/23) were then exposed to a proficient model. Only those older than 5 years provided evidence of learning from this. Accordingly, we obtained evidence for the social facilitation the study was designed to test for, and limited supplementary evidence for social learning in the older individuals who had not learned individually. These results are discussed in relation to other recent evidence for social learning in monkeys. Am. J. Primatol. 71:419–426, 2009. © 2009 Wiley‐Liss, Inc.
The influence of age, sex, population group, and dentition on the mandibular angle as measured on a South African sample
Authors: Oettlé Anna C. , Becker Piet J. , de Villiers Elzabe , Steyn Maryna
Published: February 2009

The mandibular angle is measured in physical anthropological assessments of human remains to possibly assist with the determination of sex and population affinity. The purpose of this investigation was to establish how the mandibular angle changes with age and loss of teeth among the sexes in South African population groups. The angles of 653 dried adult mandibles from the Pretoria Bone Collection were measured with a mandibulometer. Males and females of both South African whites and blacks were included. To compensate for imbalances in numbers among subgroups, type IV ANOVA testing was applied. No association was found between age and angle within either of the populations, within sexes, or within dentition groups. The angle was the most obtuse in individuals without molars and with an uneven distribution of molars, and most acute in the group with an even distribution of molars on both sides. Statistically significant differences (P < 0.001) were found in the angle between the two population groups and sexes in the overall sample as well as in the subgroup with absent molar teeth (P = 0.003 for sex, males more acute angle, and P = 0.001 for population group, blacks more acute angle), although a very large overlap existed. No significant differences could be demonstrated between the sexes or populations within the subgroups with molars. We concluded that the loss of molars, especially if complete or uneven, has a considerable effect on the mandibular angle. In the assessment of human remains, the mandibular angle is not very usable in determining sex. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.
Detection and Analysis of Low‐Abundance Cell‐Surface Biomarkers Using Enzymatic Amplification in Microfluidic Droplets
Authors: Joensson Haakan N. , Samuels Michael L. , Brouzes Eric R. , Medkova Martina , Uhlén Mathias , Link Darren R. , Andersson‐Svahn Helene
Published: February 2009

Proteine auf Zelloberflächen sind nützliche Biomarker für Krankheiten, allerdings konnten Hochdurchsatzmethoden bisher nur Zellen detektieren, die mindestens einige Hundert Proteine exprimieren. Enzymatische Amplifikation in Tröpfchen in einem Mikrofluidikgerät eignet sich zur Messung und Analyse von Biomarkern, die in geringer Konzentration auf einzelnen menschlichen Zellen exprimiert werden. Durch Farbstoffmarkierung der Tröpfchen können mehrere Proben gleichzeitig analysiert werden.

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Total Synthesis of Cribrostatin 6
Authors: Knueppel Daniel , Martin Stephen F.
Published: February 2009

Kurz und trocken: Das antimikrobielle und antineoplastische Cribrostatin 6 wurde durch eine Totalsynthese hergestellt, deren längste lineare Sequenz lediglich vier Stufen umfasste. Im Schlüsselschritt erzeugte ein Tandemprozess aus 4π‐elektrocyclischer Ringöffnung, radikalischer Cyclisierung und homolytischer aromatischer Substitution das tricyclische Gerüst des Naturstoffs.

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Titelbild: SERS‐Marker für die Anregung mit rotem Laserlicht: Glasverkapselte SAMs auf Gold/Silber‐Nanoschalen (Angew. Chem. 11/2009)
Authors: Küstner Bernd , Gellner Magdalena , Schütz Max , Schöppler Friedrich , Marx Alexander , Ströbel Philipp , Adam Patrick , Schmuck Carsten , Schlücker Sebastian
Published: February 2009

Glasverkapselte SAMs (SAM: selbstorganisierte Monoschicht) auf durchstimmbaren Au/Ag‐Nanoschalen werden von S. Schlücker et al. in der Zuschrift auf S. 1984 ff. vorgestellt. Diese Systeme haben ein großes Potenzial als Marker für die oberflächenverstärkte Raman‐Streuung (SERS) in bioanalytischen und biomedizinischen Anwendungen, die auf einer Anregung mit rotem Laserlicht beruhen, z. B. in Assays und der Mikroskopie. Die Methode kombiniert die spektroskopischen Vorteile von SAMs mit der Stabilität einer Glashülle.

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Enantioselective Catalysis Based on Cationic Oxazaborolidines
Authors: Corey E. J.
Published: February 2009

Chiral oxazaborolidines can be activated by N‐protonation using strong protic acids or by N‐coordination with AlBr3 to form very strong chiral Lewis acids. The resulting chiral boron electrophiles (see structure) are powerful chiral catalysts that effectively promote [4+2], [3+2], and [2+2]‐cycloaddition reactions with high enantioselectivity.

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Over the past several decades a revolution has occurred in chemistry that has essentially been unnoticed by those outside the field, even in other sciences. In brief, this includes the following: 1) our understanding of how chemical reactions occur, 2) our ability to invent new reactions, 3) our ability to utilize reactions that construct a vast assortment of useful or complicated molecules, and 4) our ability to apply chemical principles and knowledge to understand biological and medical problems. Within synthetic chemistry, a new science has been set in place beside the old, especially in terms of the control of absolute and relative stereochemistry and the creation of new types of useful catalysts that function in ways that were hitherto unimaginable. This Review deals with one aspect of such catalysis which has emerged only in the past six years: the generation and application of super‐Lewis acidic chiral oxazaborolidinium ions for enantioselective catalysis. Progress in this area has encompassed the formation of such catalysts, the detailed pathways of the reactions that they control and accelerate, the reactions that they can promote, and the ways in which they can be applied to advantage.
Total Synthesis and Absolute Configuration of the Bisanthraquinone Antibiotic BE‐43472B
Authors: Nicolaou K. C. , Lim Yee Hwee , Becker Jochen
Published: February 2009

An‐T‐biotic: The first total synthesis of the T‐shaped bisanthraquinone natural product BE‐43472B was accomplished and its absolute configuration assigned. Key transformations in the pivotal cascade sequence include a Diels–Alder reaction, a hemiketal formation, and a nucleophilic aromatic ipso substitution.

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Synthesis and characterization of functional copolymers of citronellol with butylmethacrylate initiated by benzoyl peroxide
Authors: Pathak Shalini , Srivastava A. K.
Published: February 2009

Benzoyl peroxide (BPO)‐initiated free radical copolymerization of citronellol with butylmethacrylate (BMA) in xylene at 80°C ± 0.1°C under the inert atmosphere of nitrogen has been studied. The kinetics expression is Rp α [I]0.5±0.27 [citronellol]1.0±0.13 [BMA]1.0±0.18. The overall activation energy has been calculated as 65 kJ/mol. Bands at 3436 and 1732 cm−1 in the FTIR spectrum of the copolymer(s) have indicated the presence of hydroxy, ester group of citronellol and butylmethacrylate, respectively. The 1H‐NMR spectrum shows peaks at 7.0–7.7 δ due to OH proton of citronellol and at 3.2–4.0 δ due to OCH2 proton of butylmethacrylate. The molecular weight Mv and ηint of the copolymers have been measured with the help of gel permeation chromatography in tetrahydrofuran at 25°C to calculate Mark‐Houwink constants as K = 2.68 × 10−4 and α = 0.34 ± 0.40. The alternating nature of the copolymer is confirmed by reactivity ratios r1 (BMA) = 0.023 ± 0.004 and r2 (Citronellol) = 0.0025 ± 0.22. The Alfrey‐Price Q‐e parameters for citronellol have been calculated as Q2 = 0.13 and e2 = –1.28. Thermal decompositions of copolymer are evaluated with the help of thermal gravimetric analysis technique. The mechanism of copolymerization has been elucidated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A general synthesis approach toward halloysite‐based composite nanotube
Authors: Li Cuiping , Liu Jiguang , Qu Xiaozhong , Yang Zhenzhong
Published: February 2009

We have demonstrated a general template synthesis halloysite‐based composite nanotube. Starting from a parent halloysite nanotube, polymer composite nanotubes were synthesized by atom transfer radical polymerization (ATRP). The shell thickness and the cavity size of the polymer composite nanotubes were tunable by altering the polymerization time. Composition of the polymer layer could be tuned by the monomers, for example, polystyrene (PS) layer was achieved by ATRP of styrene. Sulfonated PS layer (sPS) can be derived by the sulfonation of the PS layer. By specific interactions of desired materials with the sPS gel, a favorable growth of other materials, for example, metallic Ni, conductive polyaniline, inorganic titania is allowed. Besides, sPS can self‐catalyze into carbon at high temperature. Thus, the composition of the composite layers can be broadly controlled ranging within metal or metallic compounds, polymer, inorganic, carbon, and their composites. This concept is general and can be extended to other polymeric gels and grown materials, expecting a huge family of composite nanotube. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Melt rheological behavior of a triblock copolymer based on aramide end‐segments
Authors: Arun Araichimani , Gaymans Reinoud J.
Published: February 2009

Melt rheological behavior of a ABA triblock polymer made of poly(tetramethylene oxide) (PTMO) (Mn = 2,900 g mol−1) soft segment and aramide hard segment was studied. The aramide end‐segments (A) were short and mono‐disperse in length. The mid‐segment (B) consisted of PTMO2900 extended with terephthalate units to a molecular weight of 9000 g mol−1. The molecular weight of the triblock was 9700 g mol−1. Rheological behavior of this material was studied by parallel‐plate and capillary method. The ABA triblock copolymer was compared with a B polymer (PTMO‐terephthalate) of a similar molecular weight. The low molecular weight B polymer had a Newtonian behavior. The low molecular weight triblock copolymer had at high frequencies a low complex viscosity. However, at low frequencies the triblock copolymer had a very high complex viscosity. Also the G″/G′ ratio decreased with decreasing frequency to values less then one and the G′ seemed to have at low frequencies a plateau value. The activation energy of the process increased in value with decreasing shear rate. All these results indicate that the triblock copolymer at low frequencies had a gel‐like behavior and this probably due to the clustering of the aramide segments. The aramide clusters are thought to be the (weak) network points of the gel. This network was also found to have a time dependant rheological response and thus a thixotropic behavior. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Adhesion in polypropylene/aluminum laminates made by extrusion coating
Authors: Devisme S. , Haudin J.‐M. , Agassant J.‐F. , Combarieu R. , Rauline D. , Chopinez F.
Published: February 2009

The purpose of this article is to study how processing parameters can promote adhesion in grafted polypropylene/aluminum laminates made by extrusion coating. The density of bonds created at the interface is quantified by X‐ray spectroscopy after dissolution of the polymer film. dynamic mechanical analysis (DMA) and tensile tests are performed to characterize the mechanical properties of polymer films. They are linked with the crystalline structure, as revealed by optical microscopy and X‐ray diffraction. A numerical model of extrusion coating is used to quantify the impact of cooling conditions on adhesion. A good correlation is found between the temperature history, the formation of bonds, and the mechanical properties of the polymer films. High temperature conditions can improve adhesion by increasing the open time for the reaction and the rate of the chemical reaction between grafted polymer chains and aluminum. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Study of a novel halogen‐free flame retardant system through TGA and structure analysis of polymers
Authors: Jang Bok Nam , Jung Inchul , Choi Jinhwan
Published: February 2009

Butadiene‐rubber toughened styrene polymers, such as acrylonitrile‐butadiene‐styrene (ABS) copolymer and high impact polystyrene (HIPS), are noncharring polymers. They are generally blended with polycarbonate (PC) or polyphenyleneether (PPE), which are char forming polymers, to improve char forming ability for styrenic blends containing conventional phosphate flame retardants. To achieve cost effective flame retardant system, PET was selected as a potential char‐source for ABS blends through the thermogravimetric analysis (TGA) and chemical structure analysis of various polymers. PET may contribute to the enhancement of flame retardancy of ABS/PET blends, especially in the presence of small amounts of phenol novolac (PN). The effective flame retardancy of this system is believed to be accomplished through the enhancement of interchain reactions by PN. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Solvent‐crazed PET fibers imparting antibacterial activity by release of Zn2+
Authors: Weichold Oliver , Goel Pooja , Lehmann Karl‐Heinz , Möller Martin
Published: February 2009

Poly(ethylene terephthalate) fibers containing zinc chloride in the fiber bulk were prepared by solvent crazing. Fibers containing 6 g/Kg and 13 g/Kg Zn2+ were investigated. SEM‐EDX analyses and the formation of the pink bis(1,5‐dithiocarbazonato‐N,S) complex inside the fibers confirm the presence of zinc. UV‐Vis spectroscopy indicates a slow release of zinc ions into the aqueous media and, thus, the fibers serve as a release system to inhibit the growth of Escherichia coli during the first exposure. Thermal annealing of the freshly prepared fibers above Tg was shown to modify the release profile so that bacterial growth was also inhibited during repetitive and prolonged exposures. The washing fastness is fair and after 10 washing cycles, ∼ 30% of the original zinc content still remains in the fiber. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Substrate thickness: An effective control parameter for polymer thin film buckling on PDMS substrates
Authors: Hyun Dong Choon , Jeong Unyong
Published: February 2009

Buckling patterns of polymer thin films on plasma‐treated poly(dimethylsiloxane) (PDMS) substrates were sensitively affected by the thickness of the substrate in addition to the substrate modulus. On highly crosslinked PDMS substrates, the buckling wavelength of polymer thin films sharply increased as the thickness of the substrates were raised and approached a plateau value when the substrate was 2.5 mm‐thick. On weakly crosslinked PDMS substrates, the wavelength still increased even when the substrate was thicker than 20 mm. The high dependence of the buckling on the substrate thickness has not been reported before and is unexpected from the current predictions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and swelling behavior of a new superabsorbent hydrogel network based on polyacrylamide grafted onto salep
Authors: Pourjavadi Ali , Bardajee Ghasem Rezanejade , Soleyman Rouhollah
Published: February 2009

Synthesis and swelling behavior of a new superabsorbent hydrogel based on natural salep grafted with polyacrylamide is described. The new superabsorbent hydrogel biopolymer was synthesized via radical crosslinking and graft copolymerization of acrylamide monomer onto salep backbones. Regarding to the water absorption of hydrogel, the best synthesis condition is reported. FTIR spectroscopy and thermogravimetric analysis were used to confirm the structure of the final product and a mechanism for superabsorbent hydrogel formation was also suggested. After preparing the desired hydrogels based on optimum condition, several factors affecting the swelling behavior of hydrogel including pH of medium, sensitivity to the salt solution, and mixture of solvents were studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Characterization of metallocene ethylene‐1‐octene copolymers with high comonomer content cross‐linked by dicumyl peroxide or β‐radiation
Authors: Nicolás J. , Ressia J. A. , Vallés E. M. , Merino J. C. , Pastor J. M.
Published: February 2009

Two metallocene ethylene‐1‐octene copolymers differing in comonomer content were cross‐linked either by dicumyl peroxide (DCP) or β‐radiation with doses ranging from 0.5 to 4% DCP and 25 to 200 kGy, respectively. The effect of cross‐linking on the crystalline morphology was analyzed by differential scanning calorimetry (DSC). Slight alterations in the crystalline structure were found, which were more severe in the case of peroxi modification. Through infrared spectroscopy (FTIR analysis), oxidation during the cross‐linking process was detected on the DCP cross‐linked samples, while β‐irradiated samples do not exhibited significant degrees of oxidation. The state of cure was studied following the changes in the rheological properties in small‐amplitude oscillatory shear mode, and the evolution of the molecular weight and molecular weight distribution through size exclusion chromatography. Irradiation doses below 200 kGy increased the molecular weight and branching of both copolymers but were not sufficient to reach gelation. All the peroxide modified samples resulted in a post‐gel condition. Optimal mechanical properties were obtained with concentration of about 1% DCP. At higher doses, scission reactions diminish the tensile strength and the elongation at break. When polymers with equivalent amounts of gel fraction obtained by the two modification procedures studied in this work are compared, higher tensile strength and elongation at break are obtained with irradiation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Surface‐functionalization of plasma‐treated polystyrene by hyperbranched polymers and use in biological applications
Authors: Boulares‐Pender Alya , Prager‐Duschke Andrea , Elsner Christian , Buchmeiser Michael R.
Published: February 2009

Nitrogen plasma was used to amino‐functionalize polystyrene surfaces, which were further modified via the selective introduction of polyamines suitable for the immobilization of biological compounds. This chemical modification was carried out using a multifunctional amine compound linked to glutaraldehyde, leading to the formation of hyperbranched structures at the surface. Up to three generations of branched polymers at the polystyrene (PS) surface were created by successive addition of the functional compounds. Amine functions introduced at the surface were labeled with 2,3,4,5,6‐pentafluorobenzaldehyde and analyzed by X‐ray photoelectron spectroscopy (XPS), confirming the successful attachment of each generation of branching. Finally, bovine serum albumin and trypsin were immobilized on N2‐plasma‐treated PS modified with different amounts of branched graft polymer and found to remain bioactive after immobilization. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Treatment of Harakeke fiber for biocomposites
Authors: Duchemin Benoît , Staiger Mark P.
Published: February 2009

The use of fiber from Harakeke (or New Zealand Flax plant) for the reinforcement of composites should be explored since Harakeke has similar properties to Sisal fiber. To maximize the cellulose content in the fiber, Harakeke fibers were prepared by thermal, combinative alkaline‐thermal, and a novel combinative thermal‐enzymatic‐thermal treatments and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and wide‐angle X‐ray spectroscopy. The characterization method provided an efficient and systematic method to evaluate the removal of amorphous components such as lignin and hemicelluloses. In particular, a sequential thermal‐enzymatic‐thermal fiber treatment produced fine discontinuous whiskers that could be useful for short fiber composites, whereas a combinative thermal‐alkaline treatment resulted in thorough extraction of lignin and hemicelluloses. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Proton‐induced crosslinking of CR 6‐2 polycarbonate
Authors: Nouh S. A. , Mohamed Amal , Marie H. K.
Published: February 2009

CR 6‐2 polycarbonate samples were irradiated using different fluences (1011–1014 ions/cm2) of 1 MeV protons. The structural modifications in the proton‐irradiated CR 6‐2 samples have been studied as a function of fluence using different characterization techniques such as X‐ray diffraction, intrinsic viscosity of the liquid samples, as a measure of the mean molecular mass, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential thermal analysis, refractive index, color difference, and mechanical properties. The results indicate that the irradiation of CR 6‐2 detector at the fluence range 1 × 1012–5 × 1014 ions/cm2 causes intermolecular crosslinking and allows the formation of covalent bonds between different chains, leading to a more compact structure of CR 6‐2 polymer, which resulted in an improvement in its thermal, optical, and mechanical properties. Also, this crosslinking reduces the ordering structure and increases the amorphous regions that enhance the polymer resilience. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The role of information in a community of hobbyist collectors
Authors: Lee Charlotte P. , Trace Ciaran B.
Published: February 2009

This article marries the study of serious leisure pursuits with library and information science's (LIS) interest in people's everyday use, need, seeking, and sharing of information. Using a qualitative approach, the role of information as a phenomenon was examined in relation to the leisure activity of hobbyist collecting. In the process, a model and a typology for these collectors were developed. We find that the information needs and information seeking of hobbyist collectors is best represented as an interrelationship between information and object needs, information sources, and interactions between collectors and their publics. Our model of the role of information in a particular domain of hobbyist collecting moves away from the idea of one individual seeking information from formal systems and shifts towards a model that takes seriously the social milieu of a community. This collecting community represents a layer of a social system with complex interactions and specialized information needs that vary across collector types. Only the serious collectors habitually engage in information seeking and, occasionally, in information dissemination, in the traditional sense, yet information flows through the community and serves as a critical resource for sustaining individual and communal collecting activities.
A Festschrift in Honor of Professor R.W. Smithells
Authors: Seller Mary
Published: February 2009

This issue of Birth Defects Research Part A: Clinical and Molecular Teratology, comprises a Festschrift, a tribute to Professor R. W. (Dick) Smithells (1924‐2002). In the 1970s, Dick initiated a study on the prevention of neural tube defects (NTD) by periconceptional multivitamin and folic acid supplementation of ‘at risk’ women. A significantly positive result was obtained—the first time that the primary prevention of any congenital malformation had ever been achieved. This important discovery stimulated an explosion of similar and related studies, and over the years, an extension of research into many closely allied but disparate fields. The papers in this Festschrift tell some of this story. However, the story itself has, as yet, no ending, because despite Dick's pioneering work and all our accumulated knowledge, the precise cause of NTD, and its mechanism, remains unknown. The authors contributing to this issue dedicate their work to the memory of Dick, and together with many other scientists, doctors and patients worldwide acknowledge and pay homage to his inspiration, industry and foresight. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc.
The search for genetic polymorphisms in the homocysteine/folate pathway that contribute to the etiology of human neural tube defects
Authors: Molloy Anne M. , Brody Lawrence C. , Mills James L. , Scott John M. , Kirke Peadar N.
Published: February 2009

In this paper, we trace the history of current research into the genetic and biochemical mechanisms that underlie folate‐preventable neural tube defects (NTDs). The inspired suggestion by Smithells that common vitamins might prevent NTDs ignited a decade of biochemical investigations—first exploring the nutritional and metabolic factors related to NTDs, then onto the hunt for NTD genes. Although NTDs were known to have a strong genetic component, the concept of common genetic variance being linked to disease risk was relatively novel in 1995, when the first folate‐related polymorphism associated with NTDs was discovered. The realization that more genes must be involved started a rush to find polymorphic needles in genetic haystacks. Early efforts entailed the intellectually challenging and time‐consuming task of identifying and analyzing candidate single nucleotide polymorphisms (SNPs) in folate pathway genes. Luckily, human genome research has developed rapidly, and the search for the genetic factors that contribute to the etiology of human NTDs has evolved to mirror the increased level of knowledge and data available on the human genome. Large‐scale candidate gene analysis and genome‐wide association studies are now readily available. With the technical hurdles removed, the remaining challenge is to gather a sample large enough to uncover the polymorphisms that contribute to NTD risk. In some respects the real work is beginning. Although moving forward is exciting, it is humbling that the most important result—prevention of NTDs by maternal folic acid supplementation—was achieved years ago, the direct result of Smithells' groundbreaking studies. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc.
Primary microcephaly in two children born to mothers with complicated appendicitis or late appendectomy during pregnancy
Authors: Ács Nándor , Bánhidy Ferenc , Czeizel Andrew E.
Published: February 2009

BACKGROUND: The possible association between maternal appendicitis/appendectomy during pregnancy and congenital abnormalities in the offspring was studied. CASES: Two cases with primary microcephaly were born to mothers who had complicated appendicitis owing to the delay of appendectomy resulting in abscess/peritonitis associated with septicemia and fever in the second trimester of pregnancy. CONCLUSIONS: Delay in surgical intervention of appendicitis in pregnancy can result in maternal morbidity that may be associated with primary microcephaly in the offspring. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc.
Zerstörungsfreier elektrochemischer Chloridentzug an der Donaubrücke Pfaffenstein: Langzeiterfahrungen über eine bauwerksschonende und verkehrserhaltende Technologie
Authors: Schneck Ulrich
Published: February 2009

Zwischen 2003 und 2007 wurden in der Donaubrücke Pfaffenstein, die im Zuge der BAB A93 in Regensburg Donau und Donaukanal überspannt, insgesamt 200 m2 Hohlkastenbodenflächen in Teilabschnitten mit zerstörungsfreiem, elektrochemischem Chloridentzug instandgesetzt. Diese Bereiche waren durch Defekte im Entwässerungssystem der Fahrbahntafel teils erheblich chloridbelastet (bis 4%, bezogen auf die Zementmasse), so dass die Bewehrung aktiv korrodierte, aber noch keine kritischen Querschnittsverluste entstanden oder Schäden am Beton eingetreten waren. Nach Abschluss des Chloridentzugs wurden die Betonflächen, aus denen ca. 28 kg Chlorid entfernt worden sind, mehrfach – in einem Abstand von bis zu drei Jahren – mit Potentialmessungen nachuntersucht. Dabei konnte nachgewiesen werden, dass die chloridinduzierte Korrosionsaktivität – auch bei vereinzelt vorhandenem Restchloridgehalt – zuverlässig beseitigt wurde. Weder die Autobahn noch die im Arbeitsbereich unter der Brücke führende Bundesstraße waren von den Arbeiten betroffen. In diesem Beitrag sollen Wirkprinzip, Randbedingungen und die seit 2001 vom Autor gesammelten Erfahrungen mit dieser Instandsetzungsmethode besprochen werden.
Schädigung einer schlaff bewehrten Betonbrücke durch Verkehrsbelastung
Authors: Pircher Martin , Lechner Bernhard , Mariani Oliver , Kammersberger Andreas
Published: February 2009

Es wurde die Schädigung einer schlaff bewehrten Betonbrücke durch Straßenverkehr untersucht, wobei besonderes Augenmerk auf die Schädigung durch übergroße Schwertransporte (Gewicht 80t–100t) gelegt wurde. Mit einem Monitoringsystem wurde kontinuierlich sieben Wochen lang die Rissweitenänderung bereits vorhandener Biegerisse unter Verkehrsbelastung aufgezeichnet. Aus den Messdaten wurden über eine Rainflow‐Analyse die Lastzyklen bestimmt und das Spannungsspiel in der unteren Bewehrungslage ermittelt. Unter Verwendung der Palmgren‐Miner‐Regel wurde anschließend ein Mass für die Schädigung der Brücke bestimmt. Die Schädigung durch eine Überfahrt eines Sondertransports entspricht rund einer Tagesbelastung der Brücke unter Normalverkehr. Je nach Fahrtrichtung betrug die Schädigung durch Schwertransporte während des gesamten untersuchten Zeitraums zwischen 10% und 30% der gesamten Schädigung. Die Schädigung der Brücke durch dynamische Effekte betrug rund 5%, wobei die Beschaffenheit der Fahrbahnoberfläche eine große Rolle spielte.
Großversuch WILD‐Brücke – versuchsgestützte Bemessung einer UHPC‐Bogenbrücke
Authors: Freytag Bernhard , Reichel Michael , Sparowitz Lutz , Santner Gerhard , Heinzle Günter
Published: February 2009

UHPC ist aufgrund seiner Dauerhaftigkeit ein idealer Baustoff für den Brückenbau. Mit dem Bau der WILD‐Brücke hält der UHPC Einzug in Österreichs Praxis des Straßenbrückenbaus. Der extraschlanke Bogen wird über eine Spannweite von 70 m mit einer Wandstärke von 6 cm ohne schlaffe Bewehrung ausgeführt. Als Grundlage der Bemessung dienen internationale Richtlinien und maßgeschneiderte Versuche. Dieser Beitrag fokussiert auf die Auswertung von zwei Laborversuchen im Maßstab 1:1. Der Versuchsaufbau ist dahingehend konzipiert, dass die für einen Abnahmeversuch erforderliche Vielschichtigkeit der Ergebnisse zur Verfügung steht. Es werden neben den rechnerisch fassbaren kritischen Bemessungszuständen auch die mittels FE‐Analysen prognostizierten Sekundärtragwirkungen, für die es noch keinerlei praktische Erfahrung gibt, experimentell abgebildet. Die Interpretation der Versuchsergebnisse erfolgt anhand ingenieurmäßiger, mechanischer Modelle bevor sie in Form von Vergleich zwischen Messung und Rechnung beurteilt werden.
Aufstellung und Anwendung einer Nachweiskonzeption zur realitätsnahen Ermittlung der Systemtraglast an Stahlbetonschleusen
Authors: Fleischer Helmut , Lutz Matthias , Ehmann Rainer
Published: February 2009

Seit 2004 wird in der Bundesanstalt für Wasserbau (BAW) in Karlsruhe systematisch die Standsicherheit der Stahlbetonschleusen am Main‐Donau‐Kanal untersucht. Anlass war ein Schadensfall infolge Materialermüdung an der Schleuse Bamberg. Bei den Berechnungen stellte sich schnell heraus, dass bei der Anwendung geläufiger Nachweismethoden und üblicher statischer Modelle erhebliche rechnerische Sicherheitsdefizite auftreten. Um das Tragwerksverhalten der Schleusenkammern realitätsnäher abbilden zu können, sind Systemtraglastanalysen auf der Basis nichtlinearer Stoffgesetze notwendig. Als Grundlage hierfür wurde eine das Sicherheitsformat der neuen Normengeneration enthaltende Nachweiskonzeption entwickelt, die im Folgenden vorgestellt und an einem Beispiel erläutert wird.
Von der Dissoziation zum System. Das Konzept des Unbewussten als Abkömmling des Reflexparadigmas in der Theorie Freuds
Authors: Janssen Sandra
Published: February 2009

From Dissociation to System: The Concept of the Unconscious as a Descendant of the Reflex Paradigm in Freud. The paper tries to situate Freud's theory historically by referring it to a paradigm of psychological theory that Marcel Gauchet describes as the “Golden Age” of psychophysics and reflex theory, and that he situates between 1870 and 1900. I will show that until 1900 Freud thinks, in fact, in categories that correspond to this type of thought. His texts On the Psychical Mechanism of Hysterical Phenomena (1893, with Josef Breuer) and A Project for a Scientific Psychology (1895) still follow the conception of a psychological subject on the basis of the stimulus and response model, which can be found in numerous contemporaneous authors. In this model, the psyche is just a place of transit open to the exterior, and its unity can only be a sum of elements of consciousness having a physiological substrate. Nevertheless, Freud's early texts – although appertaining to the reflex paradigm – already contain elements that serve to construct another basic model of the psychic apparatus, which is finally introduced by The Interpretation of Dreams. Those new elements are the separation between interior and exterior, the introduction of endogenous energy, which is linked to the importance of emotions instead of sensations, and the problem of the adaptation to outer reality that results from it. Nevertheless, once more Freud is not the only theorist in whose thought the new paradigm can be found; I again refer his new premises to other contemporary psychologists. The question that arises from Freud's passage from one paradigm to another is how he handles the continuity of his own thought. I describe the difficult compromise between contradictory concepts he finds in his Project for a Scientific Psychology; but certain concepts that derive from the reflex paradigm subsist even during the later development of psychoanalysis. This is especially the case for the concept of the unconscious itself: As I argue, this concept originates in the reflex paradigm, and, in contrast to contemporary psychology, Freud only maintains it longer than other authors do.
Vom Reflexbogen zum psychischen Apparat: Neurologie und Psychoanalyse um 1900
Authors: Porath Erik
Published: February 2009

From Reflex Arc to Psychic Apparatus: Neurology and Psychoanalysis Around 1900. As a disciple of Ernst Wilhelm von Brücke and Theodor Meynert, Sigmund Freud was familiar with 19th century physiology and neurology. He started his career with laboratory work and began later on, when being a young medic to develop an explicit psychological method for curating hysterics. These cases of hysteria ask riddles to the established medical discourse and practice. Freud's long time unpublished Entwurf einer Psychologie (1895) makes the attempt of a “psychology for the neurologist”. He tried to give a sufficient theory of the psychic apparatus on the basis of natural science. At the same time he (together with Josef Breuer) published his Studies on Hysteria, which – in addition to his earlier essay on Aphasia (1891) – argued, that there is no clear cut relation between body and soul. Despite the dubious, non‐reductive character of the soma‐psyche‐relation, Freud gave reason to search for a complex field of interrelations between the physiological and psychological knowledge, beyond the divide of natural sciences and humanities. Not until his groundbreaking Traumdeutung (1900) Freud gave up the claim of reintegrating psychological knowledge into the neuroscientific field for now. But up to his latest work he always adheres to the principal project of unifying the natural and the psychical being of the subject. In the gap between the two spheres, for long occupied by the discursive figure of the ‘psycho‐physical parallelism’, Freud situated the Unconscious. In the passage to a psychoanalytical theory of psychic events Freud took up the model of the reflex arc well known from neurology. The transmission into psychoanalysis complexifies the unilinearity of reflexes, so that the psychic apparatus can be analysed as a cybernetic mechanism ‘avant la lettre’. It is interesting enough that inhibition as well as consciousness play a key role in the regulation of the psychic apparatus. In this context Freud stresses the importance of speech and language within the self‐organising processes concerning the claims and aims of basic needs and drives.
Facile fabrication of gelatin‐based biopolymeric optical waveguides
Authors: Manocchi Amy K. , Domachuk Peter , Omenetto Fiorenzo G. , Yi Hyunmin
Published: February 2009

The rapid development in optical detection techniques for sensing applications has led to an increased need for biocompatible, biodegradable, and disposable optical components. We present a controllable fabrication technique for an entirely biopolymeric planar optical waveguide via simple spin‐coating. The refractive index difference, thermal responsive properties, and inherent biocompatibility of gelatin and agarose were exploited in the fabrication of thin, stacked films that efficiently guide light in a core layer with higher index of refraction. These planar waveguides were fabricated using a simple spin‐coating technique, which resulted in controllable layer thicknesses and smooth layer interfaces. This technique, therefore, offers a path for routine engineering of biopolymer structures with contrasting refractive indices. The thermal stability of the gelatin core layer was improved using two crosslinkers; glutaraldehyde or microbial Transglutaminase. Light guiding in the core layer of the waveguide was demonstrated using a simple He–Ne laser setup. Guiding efficiency was further illustrated by directly embedding fluorescent markers within the core layer and detecting their spectral signature. Combined with the biopolymers' inherent biocompatibility and biodegradability, our simple strategy to fabricate disposable optical components holds the potential for the development of applications in biological sensing and implantable biomedical devices. Biotechnol. Bioeng. 2009;103: 725–732. © 2009 Wiley Periodicals, Inc.
A roadmap to robot motion planning software development
Authors: Pérez Alexander , Rosell Jan
Published: February 2009

PhD programs and graduate studies in robotics usually include motion planning among its main subjects. Students that focus their research in this subject find themselves trapped in the necessity of programming an environment where to test and validate their theoretic contributions. The programming of this robot motion planning environment is a big challenge. It requires on the one hand good programming skills involving the use of software development tools, programming paradigms, or the knowledge of computational complexity and efficiency issues. On the other hand it requires coping with different related issues like the modeling of objects, computational geometry problems and graphical representations and interfaces. The mastering of all these techniques is good for the curricula of roboticists with a motion planning profile. Nevertheless, the time and effort devoted to this end must remain reasonable. Within this framework, the aim of this paper is to provide the students with a roadmap to help them in the development of the software tools needed to test and validate their robot motion planners. The proposals are made within the scope of multi‐platform open source code. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 651–660, 2010; View this article online at wileyonlinelibrary.com; DOI 10.1002/cae.20269
Electric field effects of bundle and stranded conductors in overhead power lines
Authors: Riba Ruiz Jordi‐Roger , Espinosa Antonio Garcia , Morera Xavier Alabern
Published: February 2009

High‐voltage overhead power lines are a source of quasi‐static electric and magnetic fields and also of audible noise and electromagnetic interferences due to corona activity. Electrical engineers have the responsibility to design and to maintain such lines, so it is very important that they acquire sufficient knowledge about these subjects while they are studying. Bundle and stranded conductors modify the spatial distribution of the electric field generated by the power line and also affect the corona onset conditions. This article describes the implementation of a method that models the behavior of electric fields generated by any three‐phase power line. Different configurations of overhead power lines are analyzed. The proposed methodology has been contrasted with results from other authors and with available experimental data. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 107–114, 2011