bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of alkali and ultraviolet (UV) radiation pretreatment on physical and mechanical properties of 1,6‐hexanediol diacrylate–grafted jute yarn by UV radiation
Authors: Khan Mubarak A. , Shehrzade S. , Hassan M. Masudul
Published: February 2004

To improve the physicomechanical properties of jute yarn, grafting with 1,6‐hexanediol diacrylate (HDDA) monomer was performed by a UV radiation technique. A series of HDDA solutions of various concentrations in methanol were prepared. A small quantity of photoinitiator (Darocur‐1664) was also added to HDDA solutions. To optimize the conditions for grafting, the effects of monomer concentration, soaking time, and radiation doses were studied by varying the number of soaking times along with variation of monomer concentrations and UV radiation intensities. The extent of polymer loading and the mechanical properties like tensile strength (TS), elongation at break (Eb), and tensile modulus of both treated and untreated jute were investigated. The highest tensile strength, polymer loading, and modulus were achieved with 5% HDDA concentration, 5 min soaking time, and the 4th pass of UV radiation. This set of conditions was selected as optimum and produced enhanced tensile strength (67%), modulus (108%), and polymer loading (11%) over those of virgin fiber. To further improve the mechanical properties the jute yarns were pretreated with alkali (5% NaOH) solution and after that the alkali‐treated yarn were treated under UV radiation of various intensities. The pretreated samples were grafted with optimized monomer concentration (5% HDDA). Increased properties of alkali + UV‐pretreated and grafted samples such as polymer loading (12%), tensile strength (103%), elongation at break (46%), and modulus (114%) were achieved over those of virgin jute yarn. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 18–24, 2004
Thermomechanical behavior of poly(vinyl alcohol) and sugar cane bagasse composites
Authors: Chiellini Emo , Cinelli Patrizia , Solaro Roberto , Laus Michele
Published: February 2004

Fibers from renewable resources are gaining interest for use as fillers in hybrid composite materials. Particularly waste material such as sugar cane bagasse offer large availability, biodegradability, and low cost. Influence of single components on composite material properties is an important parameter to be evaluated. Composites of poly(vinyl alcohol) (PVA) at 88 and 98% saponification degrees and sugar cane bagasse (B) were prepared by casting water suspensions of the components and characterized for their dynamic mechanical behavior. The storage modulus below and above the glass transition and the shape of the relaxation process are strongly influenced by the amount of B. Good adhesion was observed at the lignocellulosic fiber–synthetic polymer interface. Urea and glycerol are able to plastify the PVA/B composites thus giving rise to a decrease of the glass transition temperature and to a widening of the glass transition temperature gap. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 426–432, 2004
Experimental investigations of polypropylene and poly(vinyl chloride) composites filled with plerospheres
Authors: Wang Mingzhu , Shen Zhigang , Cai Chujiang , Ma Shulin , Xing Yushan
Published: February 2004

Plerospheres, defined here as superfine spherical particles (0.5–5 μm) separated from fly ash (rather than as other solid spherical particles, as some have used the term), are separated from coal fly ash but are dramatically different from it. Plerospheres can be used as polymer fillers to improve the properties of composites. With plerospheres used as fillers for polypropylene (PP) and unplasticized poly(vinyl chloride) (UPVC), the effects of the filler content, the particle sizes of the plerospheres, and the coupling agent on the composite properties were studied. The particle sizes of the plerospheres were 2 and 5 μm. The results suggested that the notched impact properties both at a normal temperature and a low temperature and the tensile and flexural properties of plerosphere/PP increased significantly when the content was increased from 0 to 30 wt % and further increased with the addition of a coupling agent. Differential scanning calorimetry indicated that the thermal properties of the plerosphere/PP composite improved. The surface characteristics and morphology of the impact fracture surface were examined in detail with scanning electron microscopy. The rheological performance of plerosphere/UPVC pipe composites obviously improved; the plasticizing time was shortened, and the maximum torque was reduced. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 126–131, 2004
Synergistic effect between hindered amine light stabilizers and partially hindered oligomeric amines in polyethylene
Authors: Jasso A. Rosales , Duarte M. L. Berlanga , Allen N. S.
Published: February 2004

The synergistic effect between novel synthesized oligomeric amines and a commercial hindered amine light stabilizer (Chimassorb 944) was studied in medium‐density polyethylene (MDPE). Mixtures of the synthesized oligomeric amines and commercial additives were prepared at different concentrations and then were evaluated by ultraviolet and thermal aging. The evaluation was carried out on films prepared by compression molding, and the oxidation rates were monitored with Fourier transform infrared, which was used to measure the formation of different functional groups: carbonyl, vinylic, and hydroperoxide. The data showed that, independently of the concentration of the commercial additives, when they were combined with oligomeric amines, they produced a synergistic effect with a magnitude depending on the MDPE aging conditions and the additive concentrations. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 280–287, 2004
Preparation of polyhexamethyleneadipamide prepolymer by a low‐temperature process
Authors: Papaspyrides C. D. , Vouyiouka S. N. , Bletsos I. V.
Published: February 2004

The polyhexamethyleneadipamide (PA 6,6) prepolymer is prepared starting from dry hexamethylenediammonium adipate (PA 6,6 salt) by a low‐temperature polyamidation technique, which ensures balanced and free‐of‐thermal‐degradation products. The operating temperature is chosen in the vicinity of the melting point of the polyamide salt, to avoid thermal decomposition, which accompanies the higher temperatures of the conventional polyamidation processes. Two stages of prepolymerization are suggested: First, the reaction is carried out under autogenous conditions (pressurized system) to or beyond the point where diamine ends have reacted; hereafter, the system is vented so as to remove the produced water and to drive the condensation reaction toward a higher degree of polymerization. The process is demonstrated using both shaker tubes and a modified, intensively stirred autoclave. The products have balanced ends and no detectable thermal degradation effects and are used as a starting material for solid‐state finishing toward high molecular weight polyamides. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 301–306, 2004
Morphology, rheology, and mechanical properties of dynamically cured EPDM/PP blend: Effect of curing agent dose variation
Authors: Xiao Han‐Wen , Huang Shi‐Qiang , Jiang Tao
Published: February 2004

The structure development, rheological behavior, viscoelastic, and mechanical properties of dynamically cured blend based on the ethylene–propylene–diene terpolymer (EPDM) and polypropylene (PP) with a ratio of 60/40 by weight were studied. The variation of two‐phase morphology was observed and compared as the level of curing agent was increased. Meanwhile, as the level of curing agent increased, viscosity as a function of shear stress always increased at a shear stress range of 2.2 × 104 to 3.4 × 105 Pa at the temperature of 200°C, yet viscosity of the blend approached each other at high shear stress. Dynamic mechanical spectra at different temperatures show that dynamic modulus (E′) of the blend exhibits two drastic transitions corresponding to glass transition temperature (Tg) of EPDM and Tg of PP, respectively. In the blends Tgs of EPDM increase and Tgs of PP almost remain unchangeable with an increase in curing agent level. Tensile strength increased, yet elongation at break decreased as the level of curing agent is increased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 357–362, 2004
Synthesis and characterization of PBMA‐b‐PDMS‐b‐PBMA copolymers by atom transfer radical polymerization
Authors: Peng Hui , Cheng Shiyuan , Fan Zhiqiang
Published: February 2004

Poly(butyl methylacrylate)–b–poly(dimethylsiloxane)–b–poly(butyl methylacrylate) (PBMA–b–PDMS–b–PBMA) triblock copolymers were synthesized by atom transfer radical polymerization (ATRP). The reaction of α,ω‐dichloride PDMS with 2′‐hydroxyethyl‐2‐bromo‐2‐methylpropanoate gave suitable macroinitiators for the ATRP of BMA. The latter procedure was carried out at 110°C in a phenyl ether solution with CuCl and 4,4′‐di (5‐nonyl)‐2,2′‐bipyridine (dNbpy) as the catalyzing system. The polymerization was controllable, with the increase of the monomer conversion, there was a nearly linear increase of molecular weight and a decrease of polydispersity in the process of the polymerization, and the rate of the polymerization was first‐order with respect to monomer conversion. The block copolymers were characterized with IR and 1H‐NMR and differential scanning calorimetry. The effects of macroinitiator concentration, catalyst concentration, and temperature on the polymerization were also investigated. Thermodynamic data and activation parameters for the ATRP were reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 532–538, 2004
On the molecular weight distribution polydispersity of continuous living‐radical polymerization
Authors: Joseph Schork F. , Smulders Wilfred
Published: February 2004

Batch living‐radical polymerization techniques were used to produce polymers with molecular weight distributions approaching the narrowness of truly living (ionic) systems. Continuous reactors may offer some advantages for living polymerization in copolymer morphology, but continuous polymerization with any level of backmixing will broaden the molecular weight distribution. This study used simple moment techniques to demonstrate that idealized living‐radical polymerization in a single stirred tank reactor will have a polydispersity of 2. This is also the theoretical minimum polydispersity for a truly living polymerization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 539–542, 2004
Biocidal polystyrene beads. IV. Functionalized methylated polystyrene
Authors: Chen Y. , Worley S. D. , Huang T. S. , Weese J. , Kim J. , Wei C‐I. , Williams J. F.
Published: February 2004

Crosslinked chloromethylated polystyrene beads were reacted with hydantoin and imidazolidinone derivatives to produce functionalized beads which could be rendered biocidal upon reaction with free chlorine or bromine. The biocidal efficacies of the N‐chlorinated, and in one case, the N‐brominated polymeric beads against Staphylococcus aureus and Escherichia coli O157:H7 in aqueous suspension have been determined. Synthetic methods and test data have been presented. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 368–372, 2004
Characterization of films from chitosan and quaternized poly(4‐vinyl‐N‐butyl) pyridine solutions
Authors: Liu Changhua , Xiao Chaobo
Published: February 2004

All Blend films were prepared from a mixture of 2 wt % chitosan in acetate solution and 4 wt % quaternized poly(4‐vinyl‐N‐butyl) pyridine (QPVP) in aqueous solution and dried at room temperature for 72 h to obtain the films. Their structure and properties were studied by infrared (IR), wide‐angle X‐ray diffraction (WXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). Crystallinities of the blend films decreased with the increase of QPVP when weight of QPVP content was less than 15.0 wt %. The thermostability, tensile strength, and breaking elongation of the films in dry state were better than those of chitosan film. Tensile strength of the blend film dried at 40°C under vacuum for 24 h achieved 56.38 MPa when the weight ratio of chitosan to QPVP was 9 : 1. The structural analysis indicated that there was a strong interaction between chitosan and QPVP resulting from strong adhesion between both polymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 559–566, 2004
Studies on the dielectric properties of poly(o‐toluidine) and poly(o‐toluidine‐aniline) copolymer
Authors: John Honey , Thomas Rinku M. , Mathew K. T. , Joseph Rani
Published: February 2004

Poly(o‐toluidine) (PoT) and poly(o‐toluidine co aniline) were prepared by using ammonium persulfate initiator, in the presence of 1M HCl. It was dried under different conditions: room temperature drying (48 h), oven drying (at 50°C for 12 h), or vacuum drying (under vacuum, at room temperature for 16 h). The dielectric properties, such as dielectric loss, conductivity, dielectric constant, dielectric heating coefficient, loss tangent, etc., were studied at microwave frequencies. A cavity perturbation technique was used for the study. The dielectric properties were found to be related to the frequency and drying conditions. Also, the copolymer showed better properties compared to PoT alone. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 592–598, 2004
Synthesis and properties of acrylic‐based superabsorbent
Authors: Chen Xue‐Ping , Shan Guo‐Rong , Huang Jian , Huang Zhi‐Ming , Weng Zhi‐Xue
Published: February 2004

Acrylic‐based superabsorbent polymers with partial‐neutralized acrylic acid were synthesized by inverse suspension polymerization. The effects of reaction parameters, including the concentration of crosslinking agent and initiator, the neutralization degree of monomer, the monomer concentration, and phase ratio of a system, on the water absorption have been investigated. Furthermore, to improve the properties of salt‐resistance and antielectrolyte for the polymer, acrylamide monomer containing nonionic and hydrophilic groups was introduced into the system, which can suppress the salt effect and homoion effect. The water absorption Q5/3 is proportional to the reciprocal of ionic strength, 1/S, which follows Flory's elasticity gel theory. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 619–624, 2004
Name that tune: A pilot study in finding a melody from a sung query
Authors: Pardo Bryan , Shifrin Jonah , Birmingham William
Published: February 2004

We have created a system for music search and retrieval. A user sings a theme from the desired piece of music. The sung theme (query) is converted into a sequence of pitch‐intervals and rhythms. This sequence is compared to musical themes (targets) stored in a database. The top pieces are returned to the user in order of similarity to the sung theme. We describe, in detail, two different approaches to measuring similarity between database themes and the sung query. In the first, queries are compared to database themes using standard string‐alignment algorithms. Here, similarity between target and query is determined by edit cost. In the second approach, pieces in the database are represented as hidden Markov models (HMMs). In this approach, the query is treated as an observation sequence and a target is judged similar to the query if its HMM has a high likelihood of generating the query. In this article we report our approach to the construction of a target database of themes, encoding, and transcription of user queries, and the results of preliminary experimentation with a set of sung queries. Our experiments show that while no approach is clearly superior to the other system, string matching has a slight advantage. Moreover, neither approach surpasses human performance.
Bioisosterism: Quantitation of Structure and Property Effects
Authors: Kier Lemont B. , Hall Lowell H.
Published: February 2004

The powerful concept of bioisosterism is presented as a method for selecting molecular groups for drug design and lead‐compound development. Three group‐structure characteristics are described for this purpose. The E‐State value for an attached atom is used as a measure of electrotopological group impact. The volume of the group is estimated from counts of σ, π, and lone‐pair n electrons, as embodied in the valence and simple connectivity δ values for atoms in the group. Polarity is described in terms of the polarity index Qv. Specific examples are given for commonly used groups. Parameter spaces encoding these three attributes are presented as examples that may be used to guide bioisostere selection in late‐stage drug‐design procedures. The method presented here is of practical value in the decision processes of molecular modification.
TMC‐95A Analogues with Endocyclic Biphenyl Ether Group as Proteasome Inhibitors
Authors: Kaiser Markus , Milbradt Alexander G. , Siciliano Carlo , Assfalg‐Machleidt Irmgard , Machleidt Werner , Groll Michael , Renner Christian , Moroder Luis
Published: February 2004

TMC‐95A, a cyclic tripeptide metabolite of Apiospora montagnei, is a potent competitive inhibitor of proteasome. Based on the X‐ray structure of its complex with yeast proteasome, the synthetically challenging structure of this natural product was simplified in a first generation of analogues by replacing the highly oxidized side‐chain biaryl system with a phenyl‐oxindole group. In the present study, the TMC‐95 biaryl group was substituted with a biphenyl ether with retainment of significant proteasome inhibition. Because of the facile synthetic access of tripeptides containing in i, i+2 positions residues of the isodityrosine type, this new generation of TMC‐95 analogues may represent promising lead structures for further optimization of affinity and selectivity of proteasome inhibitors.
The Elusive Indigo Precursors in Woad (Isatis tinctoria L.) – Identification of the Major Indigo Precursor, Isatan A, and a Structure Revision of Isatan B
Authors: Oberthür Christine , Schneider Bernd , Graf Heidemarie , Hamburger Matthias
Published: February 2004

A metabolite‐profiling study of shock‐frozen leaves of Isatis tinctoria L., an old indigo dye plant and medicinal herb, revealed a complex pattern of indigo‐forming compounds with higher polarities than the known indigo precursors isatan B and indican. These highly unstable compounds underwent rapid post‐harvest transformation and were not detected in air‐dried leaves. The major indigo precursor, named isatan A (4), was isolated by rapid normal‐phase and gel chromatography, along with isatan B (3). A full spectral data set of 3 showed that the previous structure assignment as ‘indoxyl‐5‐ketogluconate’ has to be revised to 1H‐indol‐3‐yl β‐D‐ribohex‐3‐ulopyranoside. Isatan A (4) was identified as 1H‐indol‐3‐yl 6′‐O‐(carboxyacetyl)‐β‐D‐ribohex‐3′‐ulopyranoside. In aqueous solution, glycosides 3 and 4 occur as hydrates and undergo rapid hydrolysis under very mild acidic or basic conditions.
Synthesis and Reactivity of Homogeneous and Heterogeneous Ruthenium‐Based Metathesis Catalysts Containing Electron‐Withdrawing Ligands
Authors: Krause Jens O. , Nuyken Oskar , Wurst Klaus , Buchmeiser Michael R.
Published: February 2004

The synthesis and heterogenization of new Grubbs–Hoveyda type metathesis catalysts by chlorine exchange is described. Substitution of one or two chlorine ligands with trifluoroacetate and trifluoromethanesulfonate was accomplished by reaction of [RuCl2(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (IMesH2 = 1,3‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene) with the silver salts CF3COOAg and CF3SO3Ag, respectively. The resulting compounds, [Ru(CF3SO3)2(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (1), [RuCl(CF3SO3)(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (2), and [Ru(CF3CO2)2(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (3) were found to be highly active catalysts for ring‐closing metathesis (RCM) at elevated temperature (45 °C), exceeding known ruthenium‐based catalysts in catalytic activity. Turn‐over numbers (TONs) up to 1800 were achieved in RCM. Excellent yields were also achieved in enyne metathesis and ring‐opening cross metathesis using norborn‐5‐ene and 7‐oxanorborn‐5‐ene‐derivatives. Even more important, 3 was found to be highly active in RCM at room temperature (20 °C), allowing TONs up to 1400. Heterogeneous catalysts were synthesized by immobilizing [RuCl2(CH‐o‐iPr‐O‐C6H4)(IMesH2)] on a perfluoroglutaric acid derivatized polystyrene‐divinylbenzene (PS‐DVB) support (silver form). The resulting supported catalyst [RuCl(polymer‐CH2‐O‐ CO‐CF2‐CF2‐CF2‐COO)(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (5) showed significantly reduced activities in RCM (TONs = 380) compared with the heterogeneous analogue of 3. The immobilized catalyst, [Ru(polymer‐CH2‐O‐CO‐CF2‐CF2‐CF2‐COO)(CF3CO2)(CH‐o‐iPr‐O‐C6H4)(IMesH2)] (4) was obtained by substitution of both Cl ligands of the parent Grubbs–Hoveyda catalyst by addition of CF3COOAg to 5. Compound 4 can be prepared in high loadings (160 mg catalyst g−1 PS‐DVB) and possesses excellent activity in RCM with TONs up to 1100 in stirred‐batch RCM experiments. Leaching of ruthenium into the reaction mixture was unprecedentedly low, resulting in a ruthenium content <70 ppb (ng g−1) in the final RCM‐derived products.
Rationales Katalysatordesign am Beispiel des Methanolkatalysators
Authors: Kurtz M. , Bauer N. , Wilmer H. , Hinrichsen O. , Muhler M.
Published: February 2004

No abstracts.
Schallspektroskopische Charakterisierung konzentrierter Emulsionen
Authors: Babick F. , Ripperger S.
Published: February 2004

Da die makroskopischen Eigenschaften einer Emulsion wesentlich von ihrem Dispersitätszustand bestimmt werden, liegt der Schlüssel zur Kontrolle, von Emulgierprozessen in der prozessnahen Charakterisierung desselben. Das erfordert Partikelmesstechniken, die keinerlei Probenvorbereitung verlangen und möglichst unmittelbar im Prozess eingesetzt werden können. Eine derartige Methode zur Ermittlung von Partikelgrößenverteilungen steht mit der Ultraschallspektroskopie prinzipiell zur Verfügung. In diesem Beitrag werden die Einsatzmöglichkeiten, aber auch die Applikationsgrenzen der Ultraschallspektroskopie systematisch herausgearbeitet, indem Erfahrungen zur Präzision der Messtechnik und zur Genauigkeit der Berechnungsmodelle vorgestellt, der Informationsgehalt von Schalldämpfungsspektren sowie auch die Sensitivität gegenüber den verschiedenen Stoffparametern aufgezeigt und der Einfluss von Emulgierhilfsstoffen auf das Schalldämpfungsverhalten von Emulsionen diskutiert.
Inhibition of intra‐ and extra‐cellular Tat function and HIV expression by pertussis toxin B‐oligomer
Authors: Rizzi Chiara , Alfano Massimo , Bugatti Antonella , Camozzi Maura , Poli Guido , Rusnati Marco
Published: February 2004

HIV‐1‐transactivating factor Tat contributes to virus replication and to the onset of AIDS‐associated pathologies by targeting different infected and uninfected cell types. We previously demonstrated that the B‐oligomer of pertussis toxin (PTX‐B) inhibits HIV infection and replication in primary T cells and macrophages and Tat‐dependent HIV‐1 long terminal repeat (LTR) transactivation inT lymphoid Jurkat cells. Here we demonstrate that PTX‐B inhibits Tat‐dependent NF‐κB activation and HIV‐1 LTR‐transactivation in non‐permissive epithelial HL3T1 cells in a phosphatidylinositol 3′‐kinase‐dependent way. PTX‐B exerts its inhibition both when Tat is produced endogenously in transfected cells and in cells incubated with the extracellular Tat protein. In this latter case, PTX‐B does not interfere with extracellular Tat uptake by cells. PTX‐B inhibited also interleukin‐8 secretion and virus expression stimulated in chronically infected U1 promonocytic cells by intra‐ and/or extracellular Tat. The genetically modified holotoxin PT‐9 K/129G retains the capacity to inhibit Tat transactivating activity and HIV replication in both HIV‐permissive and non‐permissive cells. Inconclusion, PTX‐B acts as a "pleiotropic" inhibitor of Tat, and this may significantly contribute to the broad spectrum of anti‐HIV‐1 effects exerted by PTX‐B in different cell types, and suggests PTX‐B and its derivatives as prototypic for the development of anti‐Tat drugs.
Immunostimulating capacities of stabilized RNA molecules
Authors: Scheel Birgit , Braedel Sybilla , Probst Jochen , Carralot Jean‐Philippe , Wagner Hermann , Schild Hansjorg , Jung Günther , Rammensee Hans‐Georg , Pascolo Steve
Published: February 2004

Since direct injection of naked mRNA induces an immune response, we tested the capacity of RNA to signal danger. We show here that mRNA molecules that are protected from immediate degradation either through interaction with cationic proteins (trans protection) or through chemical modification of the phosphodiester backbone (phosphorothioate RNA; cis protection) act as sequence‐independent danger signals on mouse DC. As opposed to CpG DNA, the cis‐stabilized RNA is degraded in a few minutes, does not activate B cells and, in contrast to double‐stranded RNA, requires MyD88 for activation of the DC. We postulate that phosphorothioate RNA, which mimics trans‐stabilized RNA, is a new PAMP.
Natural killer T cells contribute to airway eosinophilic inflammation induced by ragweed through enhanced IL‐4 and eotaxin production
Authors: Bilenki Laura , Yang Jie , Fan Yijun , Wang Shuhe , Yang Xi
Published: February 2004

Although NKT cells have been found to be capable of modulating immune responses in several model systems, the role of NKT cells in allergy remains unclear. Using CD1 gene knockout (KO) mice, which lack NKT cells, we examined the function of NKT cells in the development of allergic inflammation induced by a common airborne human allergen, ragweed. The data showed that airway eosinophilia and mucus overproduction induced by ragweed were significantly reduced in CD1 KO mice, which was correlated with significantly lower allergen‐driven IL‐4 production and lower eotaxin responses in the airways of CD1 KO mice. Moreover, both ragweed‐specific and total serum IgE levels in CD1 KO mice were significantly lower than those in control BALB/c mice. The reduced allergic reaction in CD1 KO mice is not due to intrinsic deficiency because they showed normal levels of immune cells and function. In addition, in vivo stimulation of NKT cells using their natural ligand, α‐galactosylceramide, enhanced ragweed‐induced airway eosinophilia, IL‐4, and eotaxin production in control, but not CD1 KO mice. These data provide in vivo evidence for the involvementof NKT cells in the allergic mechanisms responsible for allergen‐driven cytokine and chemokine production and airway inflammation.
Expression profiling of IL‐10‐regulated genes in human monocytes and peripheral blood mononuclear cells from psoriatic patients during IL‐10 therapy
Authors: Jung Mechthild , Sabat Robert , Krätzschmar Jörn , Seidel Henrik , Wolk Kerstin , Schönbein Christiane , Schütt Sabine , Friedrich Markus , Döcke Wolf‐Dietrich , Asadullah Khusru , Volk Hans‐Dieter , Grütz Gerald
Published: February 2004

Interleukin‐10 (IL‐10), originally identified as an inhibitor of pro‐inflammatory cytokine production, exerts multiple immunomodulatory functions. Its ability to inhibit a Th1 response has been used in clinical trials for the treatment of inflammatory diseases including psoriasis. However, little is known about the molecular mechanisms of IL‐10 functions. We aimed at identifying possiblemediators of in vitro IL‐10 treatment in monocytes by gene chip technology using Hu95a Affymetrix mRNA arrays with 12,000 genes. To prove relevance of the identified genes for the clinicalsituation we compared these in vitro results with genes being regulated by IL‐10 in peripheral blood mononuclear cells from psoriatic patients undergoing IL‐10 therapy. A high proportion of the 1,600 genes up‐regulated and 1,300 genes down‐regulated in vitro was found to be similarly regulated in vivo. Some genes, which were previously unknown to be regulated by IL‐10, can be assigned to known IL‐10 functions like e.g. the increase of pathogen clearance. Other new potentially immunomodulating genes have been identified to be regulated by IL‐10, but their impact needs to be experimentally evaluated. We could confirm a recently reported up‐regulation of heme oxygenase‐1 (HO‐1). However, we demonstrate that the anti‐inflammatory mechanisms of IL‐10 remain functional even when HO‐1 is irreversibly inhibited.
An MHC anchor‐substituted analog of myelin oligodendrocyte glycoprotein 35–55 induces IFN‐γ and autoantibodies in the absence of experimental autoimmune encephalomyelitis and optic neuritis
Authors: Ford Mandy L. , Evavold Brian D.
Published: February 2004

Previous strategies to ameliorate experimental autoimmune encephalitis (EAE) include the treatment of autoreactive T cells with altered peptide ligands, which contain amino acid substitutions at TCR contact residues. We recently showed that a variant of myelin oligodendrocyte glycoprotein (MOG) 35–55 possessing low affinity for MHC (45D) induced anergy in MOG 35–55‐specific T cells and reduced their encephalitogenicity upon adoptive transfer. Here we investigate the characteristics of the primary immune response to this MHC anchor‐substituted peptide. Overall, we observed that immunization with 45D resulted in the production of IFN‐γ and anti‐MOG 35–55 autoantibodies at levels similar to those of MOG 35–55‐immunized mice with active EAE. However, no symptoms of clinical or histological EAE or overt histological optic neuritis were observed in 45D‐immunized mice. Consistent with this finding, 45D‐immunized mice did not exhibit CD4+ infiltrates into the CNS. Therefore, MOG 35–55‐specific precursors stimulated with a weak ligand (45D) mediate some EAE‐associated effector functions but are unable to fully initiate the inflammatory process in the central nervous system that leads to clinical manifestation of EAE.
Control of cross‐presentation during dendritic cell maturation
Authors: Gil‐Torregrosa Beatriz C. , Lennon‐Duménil Ana Maria , Kessler Benedikt , Guermonprez Pierre , Ploegh Hidde L. , Fruci Doriana , Endert Peter Van , Amigorena Sebastian
Published: February 2004

The initiation of most cytotoxic immune responses requires MHC class I‐restricted presentation of internalized antigens to CD8+ T lymphocytes, a process called cross‐presentation. In dendritic cells (DC), the only antigen‐presenting cells that activate naive T cells, cross‐presentation is particularly efficient after internalization of opsonized antigens or immune complexes, which are cross‐presented through a proteasome‐ and transporter associated with antigen processing (TAP)‐dependent MHC class I antigen presentation pathway. We now show that FcγR‐mediated cross‐presentation is tightly regulated during DC maturation. Cross‐presentation increases soon after activation by lipopolysaccharides, and it is then inhibited in fully mature cells. The initial induction of cross‐presentation results from an increase of both antigen internalization and delivery to the cytosol, and from a slight rise in the activity of the proteasome and TAP. The subsequent block of cross‐presentation in mature DC is a consequence of the selective down‐modulation of antigen internalization and cytosolic delivery, while proteasome and TAP activities continue to rise. Therefore, FcγR‐mediated cross‐presentation is regulated during DC maturation by the selective control of antigen internalization and transport to the cytosol.
Subversion of effector CD8+ T cell differentiation in acute hepatitis C virus infection: the role of the virus
Authors: Accapezzato Daniele , Francavilla Vittorio , Rawson Pisana , Cerino Antonella , Cividini Agostino , Mondelli Mario U. , Barnaba Vincenzo
Published: February 2004

In a companion study, we showed a dichotomy between the expansion of central memory (CCR7+) hepatitis C virus (HCV)‐specific CTL and the incomplete memory effector differentiation in patients with acute HCV infection. Indeed, effector cells were unable to perform immediate functions, despite expressing the tissue‐homing phenotype of effector memory cells (CCR7–; semi‐effectors). However, since they promptly differentiated into full‐effectors upon IL‐2 contact, we suggested that the inhibitory effect by environmental (possibly viral) factors on IL‐2 production may have a pivotal role in generating the large population of semi‐effector CCR7–/IFN‐γ– CTL. In accord with this view, we report here strong evidence in support of circulating HCVcore protein (HCVcore) playing a central role in inhibiting effector CTL differentiation, but not memory CTL expansion. The regulatory HCVcore effect is related to inhibition of the signal transduction pathway instrumental for IL‐2 production, supporting the evidence that IL‐2 was capable both of pushing semi‐effector CTL to complete their effector cell program and of restoring the HCVcore‐dependent inhibitory effect. Therefore, the strength of CTL activation is dependent on the balance between the threshold of stimulatory signals and the viral interference capacities provided during priming.
Identification of a TLR4‐ and TRIF‐dependent activation program of dendritic cells
Authors: Weighardt Heike , Jusek Gabriela , Mages Jörg , Lang Roland , Hoebe Kasper , Beutler Bruce , Holzmann Bernhard
Published: February 2004

Dendritic cell activation by Toll‐like receptors (TLR) is crucial for the generation of protective immune responses. In addition to the common myeloid differentiation factor 88 (MyD88)‐dependent signaling pathway, TLR4 engages the adaptor protein Toll/IL‐1 receptor (TIR)‐domain‐containing adaptor inducing IFN‐β (TRIF), leading to interferon regulatory factor 3 (IRF‐3) activation and type I interferon production. Using microarray expression profiling we now identify TRIF as a major regulator of the TLR4‐triggered activation program of dendritic cells. We show that the expressionof 47% of the genes that are responsive to TLR4 stimulation in wild‐type dendritic cells is significantly altered in cells carrying a loss‐of‐function mutation of TRIF. Specifically, expression of IL‐12, IL‐18, and IL‐23 was impaired in the absence of functional TRIF, suggesting that TLR4‐promoted Th1 responses are TRIF‐dependent. Furthermore, we provide evidence that TRIF regulates TLR4‐mediated gene expression both by type I IFN‐dependent and ‐independent mechanisms. Whereas dendritic cell production of CXCL10 and CCL12 was dependent on both TRIF and the type I interferon receptor, expression of IL‐6 required TRIF but not type I interferon activity. Functional TRIF was also required for the normal induction of numerous genes considered important for host defense against diverse pathogens.Together, these data therefore identify TRIF as a crucial regulator of TLR4‐dependent dendritic cell responses.
Commentary: T cells get by with a little help from their friends
Authors: Klenerman Paul
Published: February 2004

In animal models, lymphocytic choriomeningitis virus (LCMV) may be controlled after acute infection or may establish various levels of persistence. Cytotoxic responses mediated by CD8+ T cells are responsible for both initial control of LCMV and for immunopathology. As discussed in this article, there is emerging evidence that the levels of antigen to which the immune system is exposed over time are important in controlling CD8+ T cell activation, memory responses and exhaustion, and that these levels are affected by the efficiency of T cell help and the presence of antibody. To enable lasting control of LCMV infection, CD8+ T cells, CD4+ T cell help and B cells are all required. These findings have important implications for the preventionand treatment of infection by viruses such as hepatitis B and C viruses, cytomegalovirus and HIV.

See accompanying article http://dx.doi.org/10.1002/eji.200324717
N‐Acylhydrazines: Future Perspectives Offered by New Syntheses and Chemistry
Authors: Licandro Emanuela , Perdicchia Dario
Published: February 2004

This is a review of the most recent and useful synthetic methodologies for providing access to di‐ and trisubstituted hydrazides. New chemistry and new organometallic derivatives of the title compounds offer a new arsenal for the production of new functionalised derivatives, which are also useful as new biologically relevant molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Chemoenzymatic Synthesis of Enantiomerically Pure (2S,3R,4S)‐4‐Hydroxyisoleucine, an Insulinotropic Amino Acid Isolated from Fenugreek Seeds
Authors: Rolland‐Fulcrand Valérie , Rolland Marc , Roumestant Marie‐Louise , Martinez Jean
Published: February 2004

A short six‐step synthesis of (2S,3R,4S)‐4‐hydroxyisoleucine (1a) with total control of stereochemistry is reported, the last step being the enzymatic resolution by hydrolysis of a N‐phenylacetyl lactone derivative using the commercially available penicillin acylase G immobilized on Eupergit C (E‐PAC). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
From α,β‐Unsaturated Fischer Carbene Complexes to Highly Substituted 3‐Ethoxycyclopentadienes, Masked Cyclopentenones
Authors: Wu Yao‐Ting , Flynn Bernard , Schirmer Heiko , Funke Frank , Müller Stefan , Labahn Thomas , Nötzel Markus , de Meijere Armin
Published: February 2004

The β‐amino‐substituted α,β‐unsaturated Fischer carbene complexes 3 are readily available by a four step one‐pot procedure from terminal alkynes, chromium hexacarbonyl and secondary amines (24 examples with yields of 68−99% and 7 examples with yields of 26−63%). The formal [3+2] cycloadditions of complexes 3 with different alkynes including diynes and enynes performed in donor solvents such as pyridine or acetonitrile afforded highly substituted 5‐(dialkylamino)‐3‐ethoxycyclopentadienes 7, generally in medium to excellent yields (25 examples with yields of 60−95% and 7 examples with yields of 18−53%). The steric and electronic effects of the substituents on the carbene complexes and the incorporated alkynes on the regio‐ and stereoselectivity of the ring‐forming reaction have been elaborated. An interesting 1,5‐ or, more likely, 1,2‐migration of the dimethylamino group was observed for 5‐(dimethylamino)‐3‐ethoxycyclopentadienes with trimethylsilyl and iPr substituents at C‐5. Attempted asymmetric syntheses of cyclopentadienes 7 from complexes 3 with chiral amino groups or substituents were only moderately successful. At a center of chirality in the secondary amino group, complexes of type 3 gave compounds 7 with diastereomeric excesses of, at best, 59% in yields of 54%, and with a stereogenic center in the substituent R1 attached to the vinyl group of 3, diastereomeric excesses as high as 94% could be achieved, but with poor chemical yields (21%). In general, cyclopentenones 21 could be easily obtained from the cyclopentadienes 7 under acidic conditions in very good yields (4 examples with yields of 81−98%, 1 example with an overall yield of 50% from complex 3). Intramolecular aldol reactions of dicarbonyl compounds generated by hydrolysis of cyclopentadienes 7 with acetal‐protected aldehyde or ketone carbonyl groups in either the 5‐substituent R1 or the N‐substituent R2 led to the bicyclic compounds 22 and 23. The dimethylamino group in cyclopentenones 21 could be either eliminated or transformed into other functional groups via the quaternary ammonium salts 24. The elimination product, cyclopentadienone 27 can undergo dimerization either by a formal [4+2] or [2+2] cycloaddition. Cyclopentenone 21naaa with a bromovinyl‐terminated side chain undergoes an intramolecular Heck reaction to form 5‐methyl‐4,6‐dimethylenebicyclo[3.3.0]oct‐1‐en‐3‐one (32) (37% yield). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Overcrowded 5,10,15‐Trisubstituted Derivatives: Synthesis of 5,10,15‐Tri(fluorenylidene)truxene
Authors: Ruiz Marta , Gómez‐Lor Berta , Santos Amelia , Echavarren Antonio M.
Published: February 2004

Sterically crowded 5,10,15‐triarylated truxenes are obtained by reaction of truxenetrione with aryllithium compounds (aryl = 1‐naphthyl, 2‐naphthyl, 9‐phenanthryl, 9‐anthracenyl), followed by reduction of the tertiary alcohols with Et3SiH and BF3. Base‐catalyzed isomerization of the anti derivatives provides syn‐5,10,15‐triarylated derivatives, with the exception of the 9‐anthracenyl that could not be isomerized. Overcrowded 5,10,15‐tri(fluorenylidene)truxene was also synthesized starting form the addition of fluorenyllithium to truxenetrione. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A multiple family group intervention for first‐time juvenile offenders: Comparisons with probation and dropouts on recidivism
Authors: Quinn William H. , Van Dyke David J.
Published: February 2004

This study evaluated a multiple‐family group‐intervention program (MFGI) for first‐time juvenile offenders. The recidivism rate for subjects who completed the MFGI (the Family Solutions Program) was compared to recidivism rates of two other groups of first‐time juvenile offenders. Using logistic regression analysis predicting who will recidivate, juvenile first offenders who were placed on probation (N = 95) were 9.3 times more likely to re‐offend compared to the Family Solutions Program (FSP) graduates (N = 267). Families referred to FSP but who dropped out (most never attended the 10 session program) (N = 93) also were 4.4 times more likely to re‐offend compared to FSP graduates. An intent‐to‐treat model comparing the combined group of FSP graduates and dropouts with the probation group indicated that a youth in the probation group was 8.1 times more likely to re‐offend than a youth referred to the FSP. Results indicating better outcomes on recidivism for FSP graduates were significant for both male and female youths. Implications for policy and practitioners are discussed. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 177–200, 2004.
Mediating effects of social support on firefighters' sense of community and perceptions of care
Authors: Cowman Shaun E. , Ferrari Joseph R. , Liao‐Troth Matthew
Published: February 2004

This study examined the relationship between psychological sense of community, social‐support networks, and care‐giver stress and satisfaction among firefighters. No significant gender differences were obtained, but zero‐order correlates demonstrated significant relationships among all four variables. In examining the mediating effects of social‐support satisfaction, partial mediation for psychological sense of community on care‐giver satisfaction was determined, as well as full mediation for psychological sense of community on care‐giver stress. Therefore, firefighters who are satisfied with the support they receive may experience less stress with their care giving than those who experience low levels of support satisfaction. Future studies should assess these relationships more extensively in other areas of civic responsibility among public‐service employees to delineate effective support avenues. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 121–126, 2004.
Determination of the weaker phase in the pitting corrosion of non‐standard low‐Ni high‐Mn‐N duplex stainless steels
Authors: Merello R. , Botana F. J. , Botella J. , Marcos M.
Published: February 2004

In this paper, the use of Energy Dispersive Spectrometry (EDS) is proposed to determine the partition coefficients of the elements of a new family of duplex stainless steels that are characterized by having low contents of nickel, together with high levels of manganese and nitrogen.

From the values of the partition coefficients, the chemical compositions of the constituting phases have been determined, in order subsequently to calculate the value of the Pitting Resistance Equivalent Number (PREN) of each phase. The proposition put forward in this study is that the phase having the lower PREN determines the pitting corrosion behaviour of these types of steels.

Results obtained by means of optical and scanning electron microscopy have provided confirmation that the pitting corrosion behaviour of these new materials gets determined by the resistance of the weaker phase and consequently by the phase having the lower PREN value.

Lastly it has been proved possible to determine the existence of an exponential relationship between the alloys pitting potential (Ep) and the weaker phase PREN; this can be utilized for the low‐nickel duplex stainless steels design in which the pitting corrosion resistance is controlled.
Atmospheric corrosion of carbon steels pre‐corroded by different pollutants
Authors: Wan Y. , Yan C. , Cao C. , Tan J.
Published: February 2004

Carbon steels were pre‐corroded in atmospheres containing certain pollutants such as sulfur dioxide or hydrogen sulfide or nitrogen dioxide for certain period of time. Then the pre‐corroded samples were further exposed at two central test stations in the country to evaluate the influence of pre‐corrosion on the behavior of long‐term atmospheric corrosion of carbon steel by gravimetric measurement and rust examinations with FT‐IR and XRD. The results showed that the corrosion rates of every kind of carbon steel at Jiangjin station were two times higher than that at Beijing station. The influence of different pre‐corrosion conditions on the long‐term atmospheric corrosion of carbon steel was analyzed. It followed that the pre‐corrosion conditions made the long‐term atmospheric corrosion performance of three kinds of carbon steels different, but the differences were small. Among the three pollutants, NO2 showed the strongest influence to the process. As the exposure time was going on, all the samples corroded slowly at Beijing and Jiangjin stations.
An Ehrenfeucht‐Fraïssé class game
Authors: Boulos Lotfallah Wafik
Published: February 2004

This paper introduces a new Ehrenfeucht‐Fraïssé type game that is played on two classes of models rather than just two models. This game extends and generalizes the known Ajtai‐Fagin game to the case when there are several alternating (coloring) moves played in different models. The game allows Duplicator to delay her choices of the models till (practically) the very end of the game, making it easier for her to win. This adds on the toolkit of winning strategies for Duplicator in Ehrenfeucht‐Fraïssé type games and opens up new methods for tackling some open problems in descriptive complexity theory. As an application of the class game, it is shown that, if m is a power of a prime, then first order logic augmented with function quantifiers F1n of arity 1 and height n < m can not express that the size of the model is divisible by m. This, together with some new expressibility results for Henkin quantifiers H1n gives some new separation results on the class of finite models among various F1n on one hand and between F1n and H1n on the other. Since function quantifiers involve a bounded type of second order existential quantifiers, the class game (in a sense) solves an open problem raised by Fagin, which asks for some inexpressibility result using a winning strategy by Duplicator in a game that involves more than one coloring round. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Boolos‐style proofs of limitative theorems
Authors: Serény György
Published: February 2004

Boolos's proof of incompleteness is extended straightforwardly to yield simple “diagonalization‐free” proofs of some classical limitative theorems of logic. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A finite element model for thermomechanical analysis of sheet metal forming
Authors: Bergman G. , Oldenburg M.
Published: February 2004

A thermal model based on explicit time integration is developed and implemented into the explicit finite element code DYNA3D to model simultaneous forming and quenching of thin‐walled structures. A staggered approach is used for coupling the thermal and mechanical analysis, wherein each analysis is performed with different time step sizes. The implementation includes a thermal shell element with linear temperature approximation in the plane and quadratic in the thickness direction, and contact heat transfer. The material behaviour is described by a temperature‐dependent elastic–plastic model with a non‐linear isotropic hardening law. Transformation plasticity is included in the model. Examples are presented to validate and evaluate the proposed model. The model is evaluated by comparison with a one‐sided forming and quenching experiment. Copyright © 2004 John Wiley & Sons, Ltd.