bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of bagasse‐rind particleboard bonded with chitosan
Authors: Umemura Kenji , Kaiho Keiji , Kawai Shuichi
Published: April 2009

The development of high‐performance non‐wood lignocellulosic board without using synthetic adhesives derived from fossils resources is very important for the future. In this study, the characterization of bagasse particleboard bonded with chitosan was investigated. The 4 wt % chitosan‐acetic acid solution was sprayed onto bagasse rind particles at a 2–10 wt % chitosan solid content based on the dry particles. Particleboards with target densities of 0.75 and 0.9 g/cm3 were manufactured using a steam‐injection press. The steam pressure and total pressing time were 1 MPa (180°C) and 7 min, respectively. The addition of 2–4 wt % of chitosan was the most effective in the bending properties. The high‐density board bonded with a 4 wt % addition of chitosan showed a good result in the internal bond strength test. Furthermore, the board had favorable dimensional stability in dilute acetic acid as well as in a cyclic accelerated aging test. Judging from the analysis of bagasse extract‐added chitosan films, it was suggested that chitosan reacted with extract from bagasse during steam‐injection pressing. The reaction seemed to contribute to the board's good resistance to dilute acid. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation and characterization of flame‐retardant melamine cyanurate/polyamide 6 nanocomposites by in situ polymerization
Authors: Wu Zhi‐Yong , Xu Wei , Liu Yao‐Chi , Xia Jin‐Kui , Wu Qian‐Xin , Xu Wei‐Jian
Published: April 2009

This article focuses on an improved method, i.e., improved in situ polymerization of ε‐caprolactam in the presence of melamine derivatives to prepare flame‐retardant melamine cyanurate/polyamide 6 (MCA/PA6) nanocomposites. The chemical structures of these synthetic flame retardant composites are characterized by Fourier‐transform infrared spectroscopy and X‐ray diffraction. Morphologies, mechanical properties, and thermal properties also are investigated by the use of transmission electron microscopy, mechanical testing apparatus, differential scanning calorimetry, and thermogravimetric analysis, respectively. Through transmission electron microscopy photographs, it can be found that the in situ‐formed MCA nanoparticles with diametric size of less than 50 nm are nanoscaled, highly uniformly dispersed in the PA6 matrix. These nanocomposites, which have good mechanical properties, can reach UL‐94 V‐0 rating at 1.6‐mm thickness even at a relatively low MCA loading level. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Self‐organized nanogels from pullulan‐g‐poly(L‐lactide) synthesized by one‐pot method: Physicochemical characterization and in vitro doxorubicin release
Authors: Cho Jung‐Kyo , Park Wooram , Na Kun
Published: April 2009

Water‐insoluble pullulan‐g‐poly(L‐lactide) (PUPL) was successfully synthesized via a one‐pot method in the presence of triethylamine in dimethyl sulfoxide, in an effort to design a novel anticancer agent carrier. Three samples (designated as PUPL 1, 2, and 3) were obtained, which differed in the moles of lactides grafted to the pullulan. The degrees of grafted lactide per 1 glucose unit in pullulan were 0.68, 0.60, and 0.45 for PUPL 1, 2, and 3, respectively. These copolymers were dissolved in several organic solvents, including dimethyl sulfoxide, acetone, and ethanol, but were insoluble in water. The self‐organized nanogels were then prepared from the polymers via dialysis. To study the organizing behavior of the polymers, their critical association concentrations were measured. Their values were 5.0, 15.9, and 52.9 mg/L for PUPL 1, 2, and 3, respectively. The results showed that lactide in the polymers could function as a hydrophobic moiety for the formation of self‐organized nanogels. To estimate the potential of PUPL 1 as an anticancer drug carrier, we used doxorubicin (DOX) as a model drug. The DOX loading efficiencies of PUPL 1 were more than 52%, which differed with differing initial DOX concentrations. High loading resulted in slower DOX release as the result of increases in hydrophobic interaction. In conclusion, PUPL nanogels may prove useful as anticancer drug carriers because of their low critical association concentrations and the controlled DOX release rate © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Rheology and thermal behavior of long branching polypropylene prepared by reactive extrusion
Authors: Su Feng‐Hua , Huang Han‐Xiong
Published: April 2009

Long‐chain branching polypropylene (LCB‐PP) was achieved by reactive extrusion in the presence of bifunctional monomer [1,6‐hexanediol diarylate (HDDA)] and peroxide of dicumyl peroxide (DCP). Influences of HDDA and DCP concentrations on the branching efficiency were comparatively evaluated. Fourier transformed infrared spectroscopy (FTIR) results indicated that the grafting reaction took place, and HDDA has been grafted on PP skeleton. In comparison with initial PP, some modified samples showed lower melt flow index because of a large number of LCB in their skeleton. Several rheology plots were used to investigate the rheological properties of the initial PP and modified PPs, and the rheological characteristics confirmed the LCB in modified PPs skeleton. DSC results showed that the crystallization temperatures of modified PPs were higher than those of initial PP and degraded PP, suggesting that the modified PPs had long‐chain branched structure. The contrastive investigation in the rheology of modified PPs suggested that proper concentrations of HDDA and DCP were more beneficial to producing LCB during reactive extrusion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Characterization of fibers obtained from shredded tires
Authors: Parres F. , Crespo‐Amorós J. E. , Nadal‐Gisbert A.
Published: April 2009

The importance of recovering waste materials generated by industrialised societies is mainly due to the environmental impact they have, and one of the principal problem areas is tires. In recent years, an enormous amount of tires have been recycled. Metals contained in them have been recovered and the tire particles have been used in diverse applications. A third material that appears in the recovery process is the fibers, which act as reinforcement. Before addressing the possible reuse of these fibers, it is necessary to characterise and identify them. The diverse techniques of thermal analysis allow these fibers to be identified through melt point analysis, the results of which show the presence of polyamide 6 and 6.6. Moreover, the combination of pyrolysis‐gas chromatography/mass spectrometry corroborates the identification made with the techniques previously mentioned and also indicates the presence of certain additives used in the manufacture of tires, such as resorcinol and benzothiazole. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Carbon‐black‐reinforced natural rubber/polystyrene full interpenetrated polymer networks: Synthesis and properties
Authors: Heidary Seyed Hamid , Amraei Iraj Amiri , Payami Arash
Published: April 2009

The synthesis and properties of carbon‐black‐reinforced natural rubber/polystyrene full interpenetrated polymer networks were studied in detail. The interpenetrated polymer networks were prepared with the sequential method. The natural rubber was reinforced with 30 phr carbon black and crosslinked with 4 phr dicumyl peroxide. In all cases, natural rubber was the dominant phase in the interpenetrated polymer networks. When the polystyrene content of the interpenetrated polymer networks was increased to 12%, a good improvement in the tensile properties was observed, and the strength dropped with greater polystyrene content. Dynamic mechanical thermal analysis showed that when the tensile strength improved, there was a single phase, and a broad glass‐transition temperature peak was observed in a plot of the loss factor versus the temperature. On the contrary, when the tensile strength dropped, there was phase separation, and two glass‐transition temperature peaks were observed in a plot of the loss factor versus the temperature. In fact, there was a good relation between the static properties and dynamic properties, so we could predict static properties such as the tensile strength by an analysis of the dynamic properties. It was revealed that the phase separation of natural rubber and polystyrene depended on the component ratio and carbon black content. Also, the presence of carbon black reduced the miscibility of natural rubber and polystyrene. Thermogravimetric analysis showed that the interpenetrated polymer networks, regardless of their composition, had better thermal properties than the corresponding homopolymers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effects of the binder polymer and powder type on the resolution and edge curl of a silver electrode formed by a photolithographic process
Authors: Kim Soon Hak , Han Yoon Soo , Kwon Younghwan , Kwak Giseop , Kwon Oh Hyeong , Park Lee Soon
Published: April 2009

Silver (Ag) electrodes with a high resolution and a low edge curl dimension for plasma display panels were successfully fabricated through a photolithographic process using photosensitive Ag pastes with several polymeric binders. The gap and line resolutions of the photosensitive Ag pastes were examined as a function of the molecular weights and acid values of the acrylic binders with carboxylic acid groups. The effect on the formation of edge curls was also investigated with dry‐ and wet‐processed Ag powders. Ag electrode patterns with a line resolution of 20 μm, a gap resolution of 40 μm, and an edge curl dimension of 0.8 μm could be achieved with the developing process in 34.5 s (break point × 1.5) when the photosensitive Ag paste was prepared with the polymeric binder with a molecular weight of 23,320 g/mol and an acid value of 94.98 mg of KOH/g of polymeric binder and with dry‐processed Ag powder. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Extraction, characterization, and application of seaweed nanoparticles on cotton fabrics
Authors: Sheeba J. Mercy , Thambidurai S.
Published: April 2009

The seaweed Turbinaria conoides was collected from the east seashore of the south India. The dried seaweeds were converted into fine powder, mixed with acetone, and their antibacterial substance was extracted. The extracted substance was characterized by the use of Fourier transform infrared spectroscopy and ultraviolet–visible spectroscopy for functional group identification. The presence of bromine, amine, and phenolic groups was confirmed. Nanosized particles were confirmed by transmission electron microscopy studies. The extract was applied on the enzyme scoured and dyed cotton fabric for bioantibacterial finish. The antibacterial activity of extract on the finished fabric was confirmed by the test results. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Application of poly 3‐methylthiophene for removal of silver ion from aqueous solutions
Authors: Ansari Reza , Delavar A. Fallah
Published: April 2009

This article deals with application of poly (3‐methyl thiophene) synthesized chemically on the surface of wood sawdust (termed as P3MTh/SD) and then was used for removal of silver ions (Ag+) from aqueous solution. The polymer was synthesized directly on the surface of sawdust, which has previously soaked in monomer solution using ferric chloride as chemical oxidant. The sorption experiments were performed on both batch and column systems under simple open circuit conditions. The effects of some important parameters such as pH, initial concentration, sorbent dosage, and exposure time on uptake of silver ion were investigated. The treatment of the data was also carried out using both Freundlich and Langmuir adsorption isotherms. To find out the possibility of the regeneration and reuse of the exhausted adsorbent, desorption studies were also performed. It was found that sawdust modified with polythiophene is an efficient system for uptake or recovery of the silver ions from aqueous solutions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Prediction of the effective dielectric constant in SWNT polyimide nanocomposites using the Bruggemann model
Authors: Pérez Ricardo
Published: April 2009

The Bruggemann model is used in this work to predict the effective dielectric constant of two kinds of single‐wall carbon nanotube (SWNT) polyimide nanocomposites. Electrical conductivity and dielectric constant exhibit a dramatic enhancement at low content of SWNT fillers with a percolation threshold at 0.06 vol %. Results of the Bruggemann model are compared with the experimental values of the dielectric constant in CP2/SWNT and βCN/SWNT polyimide nanocomposites. A reasonable agreement for SWNT contents under the percolation threshold and a SWNT dielectric constant of 2000 was found between the Bruggeman model modified by Giordano and the experimental values. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Study on electrochemical behavior of Nano‐ZnO modified alkyd‐based waterborne coatings
Authors: Dhoke Shailesh K , Khanna A.S.
Published: April 2009

A nano‐composite coating was formed using nano‐ZnO as pigment in different concentrations, to a specially developed alkyd‐based waterborne coating. The nano‐ZnO modified composite coatings were applied on mild steel substrate by dipping. The dispersion of nano‐ZnO particles in coating system was investigated by scanning electron microscopic and atomic force microscopic techniques. The effect of the addition of these nano‐pigments on the electrochemical behavior of the coating was investigated in 3.5% NaCl solution, using electrochemical impedance spectroscopy. Coating modified with higher concentration of nano‐ZnO particles showed comparatively better performance as was evident from the pore resistance (Rpo) and coating capacitance (Cc) values after 30 days of exposure. In general, the study showed an improvement in the corrosion resistance of the nano‐particle modified coatings as compared with the neat coating, confirming the positive effect of nano‐particle addition in coatings. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
About the activation energies of the main and secondary relaxations in cured styrene butadiene rubber
Authors: Ghilarducci Ada , Salva Horacio , Marzocca Angel J.
Published: April 2009

This article studies the influence of the network structure on the activation energies of the α and β relaxations in vulcanized styrene butadiene rubber, SBR. A cure system based on sulphur and TBBS (N‐t‐butyl‐2‐benzothiazole sulfenamide) was used in the formulation of several compounds cured at 433 K. The activation energies were evaluated from internal friction (loss tangent) data of the compounds using an automated subresonant forced pendulum in a wide frequency range and between 80 K and 273 K. The internal friction data of the samples reveal two transitions, α and β, characterized by the temperatures Tα and Tβ, due to the glass transition and the phenyl group rotation of the copolymer, respectively. Although Tα increases at higher crosslink density, it shows also a dependence with the amount of polysulphide and monosulphide linkages present in the samples. The highest activation energy for this process is obtained for the samples with high crosslink density and 30% of monosulphides in this structure. In the case of the β‐relaxation, there is a pronounced change in the activation energy between the uncured and the cured samples. The type of structure formed during vulcanization has an important effect in the activation energy of the segmental mode‐process. In the case of the β‐process, the cis‐trans isomerization that takes place during vulcanization in the butadiene part of the SBR, might be the cause of conformational changes in the surrounding of the phenyl rings that affect the energy barrier associated to the phenyl rotation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Catalytic activity during the preparation of PE/clay nanocomposites by in situ polymerization with metallocene catalysts
Authors: Zapata Paula , Quijada Raúl , Covarrubias Cristian , Moncada Edwin , Retuert Jaime
Published: April 2009

Catalytic activity during the formation of polyethylene (PE)/clay nanocomposites by in situ polymerization with metallocenes was studied. Ethylene polymerization was carried out with the homogeneous metallocene in the presence of the clay particles and using the clay‐supported metallocene catalyst. It was found that the catalytic activity of the homogeneous metallocene does not decrease in the presence of the clay particles and only a slight decrease of activity occurs using the clay‐supported catalyst. The modification of the clay with MAO cocatalyst as well as its intercalation with ODA surfactant were found to play an important role during the in situ formation of the PE/clay nanocomposite. ODA‐intercalated clay apparently facilitates the activation and monomer insertion processes on zirconocene centers located in internal sites of the clay structure. Although metallocene supported on MAO‐treated clay exhibited somewhat lower catalytic activity than that supported directly on the ODA‐intercalated clay, both systems favored the production of PE nanocomposites containing highly exfoliated clay particles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Structure and properties of regenerated Antheraea pernyi silk fibroin filaments
Authors: Zuo Baoqi , Liu Leigen , Zhang Feng
Published: April 2009

Degummed Antheraea pernyi silk fibroin (APSF) fibers were dissolved in a lithium thiocyanate solution that was dialyzed against distilled water for 3 days. Solution‐cast APSF films were dissolved in hexafluoroisopropanol to prepare a spinning solution. Wet spinning was employed to prepare APSF filaments. Scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, solid‐state 13C cross‐polarization/magic angle spinning nuclear magnetic resonance, and differential scanning calorimetry were employed to study the regenerated APSF filaments. The results showed a uniform distribution of molecular weights, and the largest one may have been greater than 200 kDa. The regenerated filaments contained β‐sheet, α‐helix, and random‐coil conformations, and their breaking strength was 52.20% of the breaking strength of the native fibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Fe(acac)n and Co(acac)n bearing different bis(imino)pyridine ligands for ethylene polymerization and oligomerization
Authors: Wang Jingdai , Li Wei , Jiang Binbo , Yang Yongrong
Published: April 2009

A series of iron and cobalt complexes ligated with different bis(imino)pyridyl ligands were synthesized and used in ethylene polymerization. The reaction temperature and Al/Fe ratio had a great influence on the activities and properties of the polymer in the iron system when methylaluminoxane was used as the cocatalyst. Bimodal polyethylene, unimodal polyethylene, and oligomers were achieved with ethylene polymerization according to the structures of the ligands and polymerization conditions. The cobalt systems showed low activities when bis(imino)pyridyl was used as the ligand in comparison with the iron system catalysts. Ethylene oligomerization was conducted, and the main products were 1‐butylene and 1‐hexene. A fast deactivation process was observed from the curve of the polymerization kinetics. The polymerization mechanism was examined. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of ethylene glycol monobutyl ether on skin layer formation kinetics of asymmetric membranes
Authors: Li Xin , Chen Cuixian , Li Jiding , Su Yi
Published: April 2009

The present work was concerned with skin layer formation kinetics of Polyethersulfone with Cardo (PES‐C) asymmetric membranes by the phase inversion method. Gelation process was observed using an online optical microscope–CCD camera experimental system, the result indicated that a single linear correlation between square value of precipitation front move (X2) and time (t) did not exist for the whole gelation process, which was different from the traditional conclusion. The effect of Ethylene glycol monobutyl ether (EGME) on skin layer gelation process was investigated, and the skin layer formation kinetics equation was determined, which could be described with gelation rate constant equation. The gelation rate constant decreased with the increase of concentration of EGME. EGME concentrations affected the viscous flow activation energy, and the increase of viscous flow activation energy led to the decrease of gelation rate. The change trend of the gelation rate was exactly the same as that of the flux. The results helped to understand the asymmetric membrane skin layer formation process better, which was important for controlling the membrane separation properties and designing the membranes for a specific application. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Optimizing halogenation conditions of N‐halamine polymers and investigating mode of bactericidal action
Authors: Ahmed Abd El‐Shafey I. , Hay John N. , Bushell Michael E. , Wardell John N. , Cavalli Gabriel
Published: April 2009

An N‐Halamine biocidal polymer was prepared by co‐polymerizing toluene‐2,6‐diisocyanate with a new heterocyclic uramil‐based azo‐monomer, followed by halogenation. The mode of action of N‐halamine polymers on bacteria was investigated and halogenation conditions (temperature, halogenation time, halogen concentration) were optimized for bactericidal action against E. coli and S. aureus. It was found that the mode of action of this type of polymer is a combination of different factors; contact, release, and through interaction of the polymer with the bacterial medium. The most effective halogenation conditions were stirring 1 g polymer in 10 mL sodium hypochlorite (10 %) for 1 h at ambient temperature (22°C). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The transference onto God
Authors: Merkur Dan
Published: April 2009

Magical religious practices, defined as instrumental uses of the divine, are devoted to gods and God, in Winnicott's terms, as “subjectively perceived objects,” whereas the comparatively rare phenomenon of non‐magical religion is devoted to “objective objects.” In a “bargain with fate,” the divine is a transferential figure whose response to symptomatic cultic behavior is predictable and makes cultic behavior a magical means to control fate. The bargain with fate may be treated as a sublimation of the mother–infant dyad that is isomorphic with pre‐Oedipal and Oedipal fixations. The therapeutic goal, at both interpersonal and religious levels of discourse, is to facilitate advance from “object‐relating” to “object‐usage.” Analysis of the transference, arriving at a conception of the divine as a free agent, replaces the concept of fate with a concept of divine grace, interrupting the religious repetition‐compulsion. Copyright © 2009 John Wiley & Sons, Ltd.
Concept theory
Authors: Hjørland Birger
Published: April 2009

It cannot be overemphasized that changes in concepts have far more impact than new discoveries

(Mayr, 1997, p. 98)

Concept theory is an extremely broad, interdisciplinary and complex field of research related to many deep fields with very long historical traditions without much consensus. However, information science and knowledge organization cannot avoid relating to theories of concepts. Knowledge organizing systems (e.g., classification systems, thesauri, and ontologies) should be understood as systems basically organizing concepts and their semantic relations. The same is the case with information retrieval systems. Different theories of concepts have different implications for how to construe, evaluate, and use such systems. Based on “a post‐Kuhnian view” of paradigms, this article put forward arguments that the best understanding and classification of theories of concepts is to view and classify them in accordance with epistemological theories (empiricism, rationalism, historicism, and pragmatism). It is also argued that the historicist and pragmatist understandings of concepts are the most fruitful views and that this understanding may be part of a broader paradigm shift that is also beginning to take place in information science. The importance of historicist and pragmatic theories of concepts for information science is outlined.
Extracting speaker‐specific functional expressions from political speeches using random forests in order to investigate speakers' political styles
Authors: Suzuki Takafumi
Published: April 2009

In this study we extracted speaker‐specific functional expressions from political speeches using random forests to investigate speakers' political styles. Along with methodological development, stylistics has expanded its scope into new areas of application such as authorship profiling and sentiment analysis in addition to conventional areas such as authorship attribution and genre‐based text classification. Among these, computational sociolinguistics, which aims at providing a systematic and solid basis for sociolinguistic analysis using machine learning and linguistically‐motivated features, is a potentially important area. In this study we showed the effectiveness of the random forests classifier for such tasks by applying it to Japanese prime ministers' Diet speeches. The results demonstrated that our method successfully extracted the speaker‐specific expressions of two Japanese prime ministers, and enabled us to investigate their political styles in a systematic manner. The method can be applied to sociolinguistic analysis of various other types of texts, and in this way, this study will contribute to developing the area of computational sociolinguistics.
Betonangriff in eisendisulfidhaltigen Böden
Authors: Breitenbücher Rolf , Wisotzky Frank , Eisenberg Vera , Siebert Björn
Published: April 2009

In verschiedenen Regionen Deutschlands enthalten oberflächennahe Böden Eisendisulfid. Bei Zutritt von Sauerstoff, z. B. durch Bodenauflockerung im Zuge von Baumaßnahmen, kann dieses Mineral oxidieren und unter Anwesenheit von Wasser die Reaktionsprodukte Schwefelsäure und Sulfat freisetzen. Infolgedessen können sich im Baugrund saure und sulfatreiche Umgebungsbedingungen einstellen, die auf angrenzende Betonbauwerke einen kombinierten Säure‐Sulfat‐Angriff ausüben.

Das tatsächliche Ausmaß der Eisendisulfidoxidation im Baugrund und die daraus resultierenden Schädigungen in angrenzenden Betonbauwerken wurden im Rahmen eines interdisziplinären DFG‐Forschungsprojekts an der Ruhr‐Universität Bochum untersucht. Erste Ergebnisse zeigen, dass sich in eisendisulfidhaltigen Böden in Abhängigkeit von verschiedenen physikalischen und chemischen Faktoren pH‐Werte von bis zu pH 2 und Sulfatkonzentrationen von über 20.000 mg/l einstellen können. Unter diesen Bedingungen finden im angrenzenden Beton Korrosionsprozesse statt, die zunächst primär auf einen lösenden Angriff schließen lassen. Nach längerer Einwirkung von etwa einem Jahr und länger lassen sich jenseits der (Säure‐)Korrosionsfront in tieferen, bis dato ungestörten Bereichen jedoch Neubildungen sulfathaltiger Minerale beobachten, die unter Umständen auf einen voranschreitenden Sulfatangriff hindeuten.
Bauzeit und Baukosten für Stahlbetonarbeiten – Berechnungsmethoden und Anwendung
Authors: Hofstadler Christian
Published: April 2009

Die Bauzeit hat entscheidende Bedeutung hinsichtlich eines wirtschaftlich effektiven Einsatzes der Produktionsfaktoren. Zu kurze Bauzeiten führen i. d. R. zu höheren Kosten, schlechterer Qualität und zu mehr Streitigkeiten. Im Beitrag wird die Berechnung der Bauzeit unter Berücksichtigung von wesentlichen baubetrieblichen Randbedingungen gezeigt. Neben einer einfachen deterministischen Methode werden Berechnungsmöglichkeiten unter Berücksichtigung der Wahrscheinlichkeitsrechnung dargestellt. Die beschriebenen Vorgehensweisen für die Ermittlung von Bauzeit und auch der Baukosten werden anhand eines Hochbauprojekts verdeutlicht.

Mit der deterministischen Methode wird für jeden Berechnungsdurchgang ein Wert ausgegeben (Berechnungsmodus 1). Für den Berechnungsmodus 2 wird in einfacher Weise die Wahrscheinlichkeitsrechnung eingesetzt und es können für die jeweiligen Eingangsgrößen Bandbreite und Eintrittswahrscheinlichkeiten berücksichtigt werden. Für die dritte Berechnungsmethode, wird die Monte‐Carlo Methode mittels des Softwareprogramms @RISK eingesetzt. Als Ergebnis wird für die gesuchten Größen jeweils eine Wahrscheinlichkeitsverteilung dargestellt.
Cobalt‐induced oxidant stress in cultured endothelial cells: Prevention by ascorbate in relation to HIF‐1α
Authors: Qiao Huan , Li Liying , Qu Zhi‐chao , May James M.
Published: April 2009

Endothelial cells respond to hypoxia by decreased degradation of hypoxia‐inducible factor 1α (HIF‐1α), accumulation of which leads to increased transcription of numerous proteins involved in cell growth and survival. Ascorbic acid prevents HIF‐1α stabilization in many cell types, but the physiologic relevance of such effects is uncertain. Given their relevance for angiogenesis, endothelial cells in culture were used to evaluate the effects of ascorbate on HIF‐1α expression induced by hypoxia and the hypoxia mimic cobalt. Although EA.hy926 cells in culture under oxygenated conditions did not contain ascorbate, HIF‐1α expression was very low, showing that the vitamin is not necessary to suppress HIF‐1α. On the other hand, hypoxia‐ or cobalt‐induced HIF‐1α expression/stabilization was almost completely suppressed by what are likely physiologic intracellular ascorbate concentrations. Increased HIF‐1α expression was not associated with significant changes in expression of the SVCT2, the major transporter for ascorbate in these cells. Cobalt at concentrations sufficient to stabilize HIF‐1α both oxidized intracellular ascorbate and induced an oxidant stress in the cells that was prevented by ascorbate. Whereas the interaction of ascorbate and cobalt is complex, the presence of physiologic low millimolar concentrations of ascorbate in endothelial cells effectively decreases HIF‐1α expression and protects against cobalt‐induced oxidant stress. © 2009 International Union of Biochemistry and Molecular Biology, Inc.
Tandem multimer expression of angiotensin I‐converting enzyme inhibitory peptide in Escherichia coli
Authors: Fida Hasan M. , Kumada Yoichi , Terashima Masaaki , Katsuda Tomohisa , Katoh Shigeo
Published: April 2009

It is common for small tandem peptide multimer genes to be indirectly inserted into expression vectors and fused with a protein tag. In this study, a multimer of the tandem angiotensin I‐converting enzyme inhibitory peptide (ACE‐IP) gene was directly transferred to a commercially available vector and the designed gene was expressed as a repeated peptide in Escherichia coli BL21(DE3)pLysS. The process further developed in our study was the construction of six‐repeated ACE‐IP synthetic genes and their direct insertion. Protein expression in inclusion bodies was confirmed by SDS‐PAGE and Western blot. Acid hydrolysis of inclusion bodies produced single‐unit peptides through cleavage of the aspartyl‐prolyl bonds. This cleaved recombinant peptide (rACE‐IP) was purified using immuno‐affinity chromatography followed by reversed phase‐HPLC. 105–115 mg of the lyophilized recombinant peptide was obtained from 1 L E. coli culture. In vitro biological activity of rACE‐IP was indistinguishable from that of the natural peptide produced by hydrolysis in artificial gastric juice or by acidic hydrolysis. The rACE‐IP prepared by recombinant DNA technology and solid‐phase synthesis methods showed a similar IC50. This strategy could be used for the expression of important peptides, which have N‐terminal proline (P) and C‐terminal aspartic acid residues (D) for commercial applications, e.g. functional foods and drinks.
Structural, thermodynamic, and kinetic properties of Gramicidin analogue GS6 studied by molecular dynamics simulations and statistical mechanics
Authors: Zanetti‐Polzi Laura , Anselmi Massimiliano , D'Alessandro Maira , Amadei Andrea , Di Nola Alfredo
Published: April 2009

Gramicidin S (GS) analogues belong to an important class of cyclic peptides, characterized by an antiparallel double‐stranded β‐sheet structure with Type II′ β‐turns. Such compounds can be used as model systems to understand the folding/unfolding process of β‐hairpins and more in general of β‐structures. In the present study, we specifically investigate the folding/unfolding behavior of the hexameric Gramicidin S analogue GS6 by using all‐atoms molecular dynamics (MD) simulations at different temperatures, coupled to a statistical mechanical model based on the Quasi Gaussian Entropy theory. Such an approach permits to describe the structural, thermodynamic, and kinetic properties of the peptide and to quantitatively characterize its folding/unfolding transitions. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 1154–1160, 2009.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
A folded and functional synthetic PA1b: An interlocked entomotoxic miniprotein
Authors: Da Silva Pedro , Strzepa Anna , Jouvensal Laurence , Rahioui Isabelle , Gressent Frédéric , Delmas Agnès F.
Published: April 2009

PA1b (Pea Albumin 1, subunit b) is a hydrophobic, 37‐amino acid miniprotein isolated from pea seeds (Pivum sativum), crosslinked by three interlocked disulfide bridges, signature of the ICK (inhibitory cystine‐knot) family. It acts as an entomotoxic factor against major insect pests in stored crops and vegetables, making it a promising bioinsecticide. Here we report an efficient and simple protocol for the production of large quantities of highly pure, biologically active synthetic PA1b. The features of PA1b oxidative refolding revealed the off‐pathway products and competitive aggregation processes. The efficiency of the oxidative folding can be significantly improved by using hydrophobic alcoholic cosolvents and decreasing the temperature. The homogeneity of the synthetic oxidized PA1b was established by reversed‐phase HPLC. The correct pairing of the three disulfide bridges, as well as the three‐dimensional structure of synthetic PA1b was assessed by NMR. Synthetic PA1b binds to microsomal proteins from Sitophilus oryzae with a Kd of 8 nM, a figure quite similar to that determined for PA1b extracted from its natural source. Moreover, the synthetic miniprotein was as potent as the extracted one towards the sensitive strains of weevils. Our findings will open the way to the production of PA1b analogues by chemical means to an in‐depth understanding of the PA1b mechanism of action. © 2009 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 92: 436–444, 2009.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Specific labeling with potent radiolabels alters the uptake of cell‐penetrating peptides
Authors: Walther Cornelia , Ott Ingo , Gust Ronald , Neundorf Ines
Published: April 2009

Radiolabeled peptides play an important role in radiopharmacy not only as tumor markers but also as transport vectors. Therefore, cell‐penetrating peptides (CPP) may serve as very effective delivery tools, as well. Recently, CPP based on the human hormone calcitonin (hCT) have been developed. Especially, branched hCT‐peptide sequences turned out to have highly efficient internalization capacities. Labeling these peptides with radionuclides would generate promising new tools for imaging and therapy applications in radiopharmacy. However, the influence of the metal complexation on the internalization capacity of CPP has not been elucidated yet in detail. In this study we quantified the uptake of Ga‐DOTA modified hCT‐carrier peptides in HeLa cells by using atomic absorption spectroscopy (AAS) and compared the results to the uptake of fluorescently‐labeled peptides. Interestingly, we measured different uptake rates depending on the attached label. Unexpectedly, modification with a Ga‐DOTA complex can have tremendous effects on the uptake efficiency. The results of these studies support the need of detailed analysis of each carrier peptide/cargo construct, especially in the field of metal complex modified CPP. © 2009 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 92: 445–451, 2009.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Particle concentration and yield stress of biomass slurries during enzymatic hydrolysis at high‐solids loadings
Authors: Roche Christine M. , Dibble Clare J. , Knutsen Jeffrey S. , Stickel Jonathan J. , Liberatore Matthew W.
Published: April 2009

Effective and efficient breakdown of lignocellulosic biomass remains a primary barrier for its use as a feedstock for renewable transportation fuels. A more detailed understanding of the material properties of biomass slurries during conversion is needed to design cost‐effective conversion processes. A series of enzymatic saccharification experiments were performed with dilute acid pretreated corn stover at initial insoluble solids loadings of 20% by mass, during which the concentration of particulate solids and the rheological property yield stress (τy) of the slurries were measured. The saccharified stover liquefies to the point of being pourable (τy ≤ 10 Pa) at a total biomass conversion of about 40%, after roughly 2 days of saccharification for a moderate loading of enzyme. Mass balance and semi‐empirical relationships are developed to connect the progress of enzymatic hydrolysis with particle concentration and yield stress. The experimental data show good agreement with the proposed relationships. The predictive models developed here are based on established physical principles and should be applicable to the saccharification of other biomass systems. The concepts presented, especially the ability to predict yield stress from extent of conversion, will be helpful in the design and optimization of enzymatic hydrolysis processes that operate at high‐solids loadings. Biotechnol. Bioeng. 2009; 104: 290–300 © 2009 Wiley Periodicals, Inc.
Interplay between light intensity, chlorophyll concentration and culture mixing on the hydrogen production in sulfur‐deprived Chlamydomonas reinhardtii cultures grown in laboratory photobioreactors
Authors: Giannelli Luca , Scoma Alberto , Torzillo Giuseppe
Published: April 2009

Relationships between light intensity and chlorophyll concentration on hydrogen production were investigated in a sulfur‐deprived Chlamydomonas reinhardtii culture in a laboratory scale photobioreactor (PBR) equipped with two different stirring devices. In the first case, the culture was mixed using a conventional magnetic stir bar, while in the second it was mixed using an impeller equipped with five turbines. Experiments were carried out at 70 and 140 µmol photons m−2 s−1 in combination with chlorophyll concentrations of 12 and 24 mg L−1. A high light intensity (140 µmol photons m−2 s−1, supplied on both sides of the PBR) in combination with a low chlorophyll concentration (12 mg L−1) inhibited the production of hydrogen, in particular in the culture mixed with the stir bar. An optimal combination for hydrogen production was found when the cultures were exposed to 140 µmol photons m−2 s−1 (on both sides) and 24 mg L−1 of chlorophyll. Under these conditions, the hydrogen production output rate reached about 120 mL L−1 in the culture mixed with the stir bar, and rose to about 170 mL L−1 in the one mixed with the impeller. These outputs corresponded to a mean light conversion efficiency of 0.56% and 0.81%, respectively. However, the efficiency increased to 1.08% and 1.64%, respectively, when maximum hydrogen rates were considered. The better performance of the dense cultures mixed with an impeller was mainly attributed to an intermittent illumination pattern to which the cells were subjected (time cycles within 50–100 ms) which influenced the hydrogen production (1) directly, by providing the PSII with a higher production of electrons for the hydrogenase and (2) indirectly, through a higher synthesis of carbohydrates. The fluid dynamics in the PBR equipped with the impeller was characterized. The better mixing state achieved in the PBR of the new configuration makes it a useful tool for studying the hydrogen production process involving photosynthetic microorganisms, and provides a better insight into the physiology of the process. Biotechnol. Bioeng. 2009; 104: 76–90 © 2009 Wiley Periodicals, Inc.
Causes of shear sensitivity of the toxic dinoflagellate Protoceratium reticulatum
Authors: Rodríguez J. J. Gallardo , Mirón A. Sánchez , Camacho F. García , García M. C. Cerón , Belarbi E. H. , Chisti Y. , Grima E. Molina
Published: April 2009

Dinoflagellates have proven extremely difficult to culture because they are inhibited by low‐level shear forces. Specific growth rate of the toxic dinoflagellate Protoceratium reticulatum was greatly decreased compared with static control culture by intermittent exposure to a turbulent hydrodynamic environment with a bulk average shear rate that was as low as 0.3 s−1. Hydrodynamic forces appeared to induce the production of reactive oxygen species (ROS) within the cells and this caused peroxidation of cellular lipids and ultimately cell damage. Exposure to damaging levels of shear rate correlated with the elevated level of lipoperoxides in the cells, but ROS levels measured directly by flow cytometry did not correlate with shear induced cell damage. This was apparently because the measured level of ROS could not distinguish between the ROS that are normally generated by photosynthesis and the additional ROS produced as a consequence of hydrodynamic shear forces. Continuously subjecting the cells to a bulk average shear rate value of about 0.3 s−1 for 24‐h caused an elevation in the levels of chlorophyll a, peridinin and dinoxanthin, as the cells apparently attempted to counter the damaging effects of shear fields by producing pigments that are potential antioxidants. In static culture, limitation of carbon dioxide produced a small but measureable increase in ROS. The addition of ascorbic acid (0.1 mM) to the culture medium resulted in a significant protective effect on lipid peroxidation, allowing cells to grow under damaging levels of shear rates. This confirmed the use of antioxidant additives as an efficient strategy to counter the damaging effects of turbulence in photobioreactors where shear sensitive dinoflagellates are cultivated. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Effect of periplasmic nitrate reductase on diauxic lag of Paracoccus pantotrophus
Authors: Durvasula Kiranmai , Jantama Kaemwich , Fischer Kyle , Vega Adrian , Koopman Ben , Svoronos Spyros A.
Published: April 2009

Paracoccus pantotrophus expresses two nitrate reductases—membrane bound nitrate reductase (Nar) and periplasmic nitrate reductase (Nap). In growth experiments with two denitrifying species (Paracoccus pantotrophus and Alcaligenes eutrophus) that have both Nap and Nar and two species (Pseudomonas denitrificans and Pseudomonas fluorescens) with Nar only, it was found that diauxic lag is shorter for bacteria that express Nap. In P. pantotrophus, napEDABC encodes the periplasmic nitrate reductase. To analyze the effect of Nap on diauxic lag, the nap operon was deleted from P. pantotrophus. The growth experiments with nap− mutant resulted in increased diauxic lag when switched from aerobic to anoxic respiration, suggesting Nap is responsible for shorter lags and helps in adaptation to anoxic metabolism after transition from aerobic conditions. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
An undergraduate fuzzy logic control lab using a line following robot
Authors: Ibrahim Dogan , Alshanableh Tayseer
Published: April 2009

Fuzzy logic controllers have gained popularity in the past few decades with highly successful implementation in many fields. Fuzzy logic enables designers to control complex systems more effectively than traditional methods. Teaching students fuzzy logic in a laboratory can be a time‐consuming and an expensive task. This paper presents a low‐cost educational microcontroller‐based tool for fuzzy logic controlled line following mobile robot. The robot is used in the second year of undergraduate teaching in an elective course in the department of computer engineering of the Near East University. Hardware details of the robot and the software implementing the fuzzy logic control algorithm are given in the paper. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 639–646, 2011
Cover Picture: A Pan‐Specific Inhibitor of the Polo‐Box Domains of Polo‐like Kinases Arrests Cancer Cells in Mitosis (ChemBioChem 7/2009)
Authors: Reindl Wolfgang , Yuan Juping , Krämer Andrea , Strebhardt Klaus , Berg Thorsten
Published: April 2009

The cover picture shows the small molecule Poloxipan, a pan‐specific inhibitor of polo‐like kinases (Plks), and its effects on human cancer cells. Most inhibitors of protein kinases such as Plk1, which is a key player in mitosis, inhibit the enzyme ATP‐binding pocket. Due to the conserved nature of the ATP‐binding pocket in protein kinases, this approach is frequently associated with specificity problems. In addition to their catalytic domain, polo‐like kinases contain a unique protein–protein interaction domain dubbed “polo‐box domain”, which is used by the enzymes to bind to their respective intracellular anchoring sites. On p. 1145 ff. of this issue, Berg, Strebhardt et al. explore the concept of inhibiting Plk1 by targeting the function of its polo‐box domain with Poloxipan, and find that the molecule induces mitotic arrest accompanied by a characteristic cellular phenotype called “chromosome congression defects”. This phenotype is represented by failure of one or more chromosomes to congress to the metaphase plate of mitotic cells, and is distinct from the phenotype observed with ATP‐competitive inhibitors of Plk1.

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Use of interlock fibered detachable coils for occlusion of collaterals, coronary artery fistulae, and patent ductus arteriosus
Authors: Seltzer Sharon , Aboulhosn Jamil , Levi Daniel S.
Published: April 2009

Objective: To investigate the utility of Interlocking Detachable Coils™ (IDC) for transcatheter occlusion of vascular communications in congenital heart disease. Background: The IDC can be delivered in a retractable fashion through hydrophilic Renegade™ microcatheters. They incorporate thrombogenic synthetic fibers and cost less than comparable neurovascular coils. They are ideally suited for use in many forms of congenital heart disease. Methods: A retrospective review of all patients catheterized during the initial 18‐month period of IDC availability at our institution was performed. Interlock coils were only used if traditional methods could not be used easily and safely. All congenital patients in whom IDC were used are described. Results: A total of 61 coils were deployed in 17 patients with various vessels not amenable to treatment with conventional coils. Coils were used in aortopulmonary collaterals (n = 7), veno‐venous collaterals (n = 9), patent ductus arteriosus (n = 3), and coronary artery fistulae (CAF) (n = 2). Operators were able to control coils and withdraw into the catheter for repositioning without difficulty. Thirteen of 21 vessels demonstrated immediate occlusion. All late angiograms have demonstrated complete occlusion of all vessels, with one exception requiring reintervention. One coil migrated from a large CAF and was easily retrieved with a snare. No serious complications occurred. All patients had an uneventful postcatheterization course. Conclusions: Transcatheter vascular coil embolization with IDCs can be performed safely and effectively in a variety of circumstances. © 2009 Wiley‐Liss, Inc.