bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kontrolle beim Mikroschweißen – Automatisierte Prozessüberwachung durch koaxiale Prozesskontrolle mit Fremdbeleuchtung
Authors: Gedicke Jens , Regaard Boris , Gillner Arnold , Kaierle Stefan 
Published: February 2007

AbstractAls flexibles und leistungsfähiges Fügewerkzeug ist der Laser seit langem in der Produktionstechnik etabliert. Insbesondere das Schweißen mit Laserstrahlung kann seit geraumer Zeit als Stand der Technik angesehen werden. Vor dem Hintergrund steigender Miniaturisierungstendenzen hat die Lasertechnik dabei auch kontinuierlich Einzug in den Bereich der Mikrotechnik gehalten und ist heute aus der Fertigung mikrotechnischer Bauteile und Baugruppen nicht mehr wegzudenken. Neue Fügeverfahren und Strahlquellen, die den technischen und ökonomischen Anforderungen von Serienfertigungsprozessen gerecht werden, erlauben es heute, viele mikrotechnische Fügeaufgaben prozesssicher unter Produktionsbedingungen umzusetzen.
Pre‐, In‐ und Post‐Process‐Verfahren – Die Prozesssicherung fordert verschiedene Verfahren
Authors: Trbola Johannes F. 
Published: February 2007

AbstractUm gleich bleibende Qualität in der Lasermaterialbearbeitung garantieren zu können, müssen Herstellungsprozesse exakt gesichert werden. Standards wie ISO 9000 und VDA 6/4 – um nur zwei Schlagworte zu nennen – haben sich daher in vielen Bereichen durchgesetzt, insbesondere auch beim Laserschweißen. Demzufolge sind die Anforderungen an die Absicherung, aber auch die Dokumentation der Schweißprozesse immer wichtiger geworden.
Qualitätsüberwachung von Getriebeteilen – Neue Prüfungssysteme ersetzen die Sichtprüfung
Authors: Wildmann Daniel , Mootz Andreas 
Published: February 2007

AbstractLaserfügen im Automobilbau ist seit mehr als zehn Jahren für verschiedenste Getriebe‐ und Karosserieteile Stand der Technik. Angefangen mit der wichtigsten Anwendung, dem Schweißen von Tailored Blanks, mit weltweiten Produktionszahlen von über 250 Millionen Teilen und weiterem stetigen Wachstum in den nächsten Jahren, ist der Laser heute im Karosserierohbau und in der Teilefertigung nicht mehr wegzudenken. Beim geforderten hohen Qualitätsstandard bedürfen diese großen Volumina voll au to matisierter Lösungen im Bereich Qualitätsprüfungssysteme, da die von Menschen durchgeführte Sichtprüfung auf fehlerhafte Lasernähte zu teuer und nicht zuverlässig genug ist.
Leistungsskalierung von Lasern – Echte Skalierbarkeit bedeutet weit mehr als eine einfache Erhöhung der Leistung
Authors: Paschotta Rüdiger 
Published: February 2007

AbstractLeistungsskalierbarkeit ist ein wichtiges Konzept, welches gewisse Laserdesigns auszeichnet, andere dagegen nicht. Was genau bedeutet jedoch Leistungsskalierung? Welche Bedeutung hat sie für die Praxis? Und welche Methoden werden verwendet?
Industrielle Bildverarbeitung – Schlüsseltechnologie moderner Produktionssysteme
Authors: Modrich Kai‐Udo 
Published: February 2007

AbstractVerschiedene Studien belegen: Qualität gilt nach wie vor als der Wettbewerbsfaktor Nummer eins im produzierenden Gewerbe. Und sie steht damit noch vor anderen Faktoren wie Innovation und Flexibilität. Für die industrielle Produktion bedeutet dies, dass Prozessketten die notwendige Prozesssicherheit aufweisen müssen, um die geforderte Qualität produzieren zu können.
Clevere Kombination: Laser‐Beleuchtung und Bildverarbeitung
Authors: Stiefenhöfer Peter 
Published: February 2007

AbstractDie Kombination von Laser‐Beleuchtungen und Bildverarbeitung bietet interessante Möglichkeiten für die Automatisierung optischer Qualitätskontrollen. Eine Kooperation zwischen dem Freiburger Laser‐Hersteller Z‐LASER und dem Puchheimer Bildverarbeitungs‐Spezialisten STEMMER IMAGING erschließt diese Wege.
Aus der Ferne betrachtet – Prozessüberwachung beim Remote‐Laserstrahlfügen und ihre Möglichkeiten
Authors: Müller‐Borhanian Jürgen , Kogel‐Hollacher Markus 
Published: February 2007

AbstractDie stark verbesserten Strahlqualitäten der modernen Festkörperlasersysteme, bzw. die sehr guten Strahlqualitäten der CO2‐Laser haben einer neuartigen Fertigungsstrategie den Weg in die industrielle Produktion gebahnt, dem Remote‐Laserstrahlfügen mit großen Fokuslängen. Mit diesem Verfahren können im Vergleich zum konventionellen Punktschweißen die Taktzeiten um bis zu 60% verkürzt werden. Das alleine macht diese Technologie schon für Bereiche wie den Karosserierohbau interessant.
Not just another laser platform – Quo Vadis Fiber Lasers
Authors: Stenius Per 
Published: February 2007

AbstractFiber lasers have been a hot topic in laser conferences and industry meetings for several years now, and are finally starting to appear en masse in the market place. Currently the industrial fiber laser market is in practice completely dominated by IPG, which is enjoying strong growth and now poised for an IPO. In this article we seek to provide a big‐picture perspective on fiber lasers, the underlying technologies, the commercialization challenges, and the changes in the market fiber lasers are likely to bring about.
Fokussierung von High‐Brightness‐Lasern – Neue High‐Power‐Laser erfordern neue Optiken
Authors: Wedel Björn , Niedrig Roman 
Published: February 2007

AbstractDer Faserlaser und auch der Scheibenlaser sind Laser mit einer sehr hohen Brightness (Brillianz). Ihre Ausgangsleistungen gehen derzeit bis etwa 30 kW, wobei 5–8 kW durchaus schon als typisch gelten. Kennzeichnend sind sehr gute Strahlqualitäten, die bis in den Kilowatt‐Bereich beugungsbegrenzt sind, bzw. bei Leistungen von 20 kW noch bei 10 bis 20 mm*mrad liegen.
CCD‐ und CMOS‐Bildsensoren – Grundbegriffe und Applikationen in der Lasertechnik
Authors: Schwider Peter Mario 
Published: February 2007

AbstractIn der Vergangenheit wurde der Vergleich beider Sensortechnologien zu einem Wettkampf hochstilisiert. Dabei führen sehr grobe und vereinfachende Annahmen beim Vergleich von CCD‐ und CMOS‐Bildsensoren oft zu Fehlurteilen. Jede dieser Technologien besitzt Vor‐ und Nachteile. Allein die Anwendung (Applikation) bestimmt die Wahl des Detektors, wobei immer Kompromisse eingegangen werden müssen, da es den idealen Bildsensor nicht gibt.
20 Jahre ganzheitliche Laserforschung für die Fertigungstechnik am IFSW
Authors: Graf Thomas , Hügel Helmut 
Published: February 2007

AbstractMit einer “Familienfeier” im Kreise der heute aktiven und zahlreichen ehemaligen Mitarbeitern beging das Institut für Strahlwerkzeuge (IFSW) der Universität Stuttgart in diesem Frühjahr sein zwanzigjähriges Bestehen. Wenngleich angesichts der zahlreichen offiziellen Anlässe im Vorfeld des Jubiläums (Institutsleiternachfolge, Stuttgarter Lasertage) bewusst auf eine weitere öffentliche Veranstaltung verzichtet wurde, bieten zwei Dekaden erfolgreicher Arbeit doch hinreichend Anlaß, einen Blick auf diese Zeit und die Forschungstätigkeit am IFSW zu werfen. In einer solchen Rückschau spiegeln sich all die Strömungen und Entwicklungslinien wieder, welche der industriellen Lasertechnik in Deutschland zu ihrer weltweiten Spitzenposition verhalfen. Aus dieser Sicht mögen dann auch die nicht unwesentlichen Beiträge, welche das IFSW hierzu geleistet hat, sowie eine Standortbestimmung zur Definition der künftigen Forschungsschwerpunkte erkennbar werden.
Chemical Recycling of Poly(ethylene terephthalate)
Authors: Karayannidis George P. , Achilias Dimitris S. 
Published: February 2007

AbstractThis paper covers the recent research carried out by the authors on the chemical recycling of poly(ethylene terephthalate) (PET) taken from post‐consumer soft‐drink bottles. The chemical recycling techniques used are critically reviewed and the authors' contribution is highlighted. Hydrolysis in either an alkaline or acid environment was employed in order to recover pure terephthalic acid monomer that could be repolymerized to form the polymer again. Alkaline hydrolysis was carried out in either an aqueous NaOH solution or in a non‐aqueous solution of KOH in methyl cellosolve. A phase‐transfer catalyst was introduced in alkaline hydrolysis, in order that the reaction takes place at atmospheric pressure and in mild experimental conditions. The reaction kinetics were thoroughly investigated, both experimentally and theoretically, using a simple, yet precise, kinetic model. Moreover, glycolysis was examined as an effective way for the production of secondary value‐added materials. The glycolysated PET products (oligomers) can be used as raw materials for the production of either unsaturated polyester resins (UPR) or methacrylated oligoesters (MO). UPR can subsequently be cured with styrene in ambient temperature to produce alkyd resins used as enamel paints or coatings. MO are potential monomers that can be cured either by UV irradiation or temperature to produce formulations used as coatings for wood surfaces, paints, or other applications. Thus, recycling of PET does not only serve as a partial solution to the solid‐waste problem, but also contributes to the conservation of raw petrochemical products and energy.magnified image
Time‐Temperature Creep Behaviour of Poly(propylene) and Polar Ethylene Copolymer Blends
Authors: Genovese Antonietta , Shanks Robert A. 
Published: February 2007

AbstractPolymers commonly undergo deformation under an applied stress over their lifetime; some deformations are irrecoverable once the source of stress is removed. Therefore an understanding of the response of a polymer can be achieved by investigating the viscoelastic properties using creep experiments, where the behaviour can be monitored under small deformational loads. Poly(propylene) (PP) was blended with a polar elastic, thermoplastic, poly[ethylene‐co‐(methyl acrylate)] (EMA), to toughen the matrix. EMA formed a dispersed phase in PP that maintained its strength through its crystallinity rather than crosslinking. EMA can form a compatible interface with PP through inclusion of maleated‐PP as a compatibiliser. The viscoelasticity of the PP–EMA blends, particularly the creep behaviour is an important factor if the properties of PP are to be maintained. The creep and recovery of PP–EMA blends with varying compositions were investigated under different loads and number of cycles. High EMA content provided an alternative deformation pathway due to its elastomeric properties. The experimental creep behaviour has been evaluated using the 4‐element model with some limitations evident in the viscoelastic transitional region.magnified image
Structure, Morphology and Properties of a Novel Molecular Composite by In‐Situ Blending of Anionic Polyamide 6 with a Polyamide Copolymer Containing Rigid Segments
Authors: Wang Xiaochun , Yang Guisheng , Zheng Qiang 
Published: February 2007

AbstractMolten caprolactam, in which a polyamide copolymer (HPN) containing rigid segments was dissolved, was polymerized by means of anionic ROP to in produce polyamide (PA, nylon) 6 blends with HPN in situ. A novel molecular composite was achieved in which toughness and strength were simultaneously improved, as well as modulus, compared to virgin PA6. In view of the interchange reaction between PA6 and PA1212 (and PA66) in blends fabricated in the same way, it was deduced that a similar reaction between PA6 and HPN took place during the blending and led to copolymerization between the two components. The formation of copolymers was verified by their single glass transition and single melting peak, measured through DMA and DSC, respectively. DSC analysis also showed that the occurrence of the interchange reaction inhibited the crystallization and suppressed the melting point of PA6. Analysis by FT‐IR spectroscopy indicated that the difference in the distance between the amide groups for PA6 and HPN induced a decrease in the amount and strength of hydrogen bonding. Moreover, characterization by POM and XRD revealed that the spherulite size of the PA6 crystals decreased dramatically and the amount of γ crystal increased slightly with the majority of crystallites being α crystals. Furthermore, it was found through the observation of the morphology by SEM that no phase separation existed in the composites. On the basis of detailed analysis and a comparison between the in situ PA6/PA66 and PA6/HPN blends, it is believed that the combination of markedly decreasing spherulite size and similar segmental mobility resulted in the simultaneous improvement of mechanical properties for the in situ PA6/HPN blends.magnified image
Flame‐Retarded Poly(propylene) with Melamine Phosphate and Pentaerythritol/Polyurethane Composite Charring Agent
Authors: Liu Meifang , Liu Yuan , Wang Qi 
Published: February 2007

AbstractIn this paper, a novel intumescent system including MP as well as PER/TPU which acts as composite charring agent, is adopted to flame‐retarded PP. The encapsulation of charring agent PER by TPU effectively avoids the reaction of PER with MP during the compounding with PP at high temperature and also prevents the leaching out of polar PER from nonpolar PP matrix, thus remarkably enhancing the stability and water‐resistance of the intumescent system. PER and TPU have different but complementary charring mechanisms. So flame‐retarded PP with MP/composite charring agent shows a much better charring performance and flame‐retardancy than MP/PER flame‐retarded PP. The experimental results show that the former can reach UL‐94 V‐0 rating at 1.6 mm thickness at 25 wt.‐% flame retardant loading.magnified image
Preparation and Thermoplastic Processing of Modified Plant Proteins
Authors: Bräuer Silke , Meister Frank , Gottlöber Ralf‐Peter , Nechwatal Axel 
Published: February 2007

AbstractNative plant proteins such as gluten, zein, soy and pea protein were chemically modified by acylation reactions using palmitic acid chloride and alkenyl‐substituted succinic anhydrides, respectively. The goal of this work was the development of novel, biodegradable protein materials, which are processable by thermoplastic shaping in extruders. Structures and properties of modified plant proteins were characterized by elementary analysis, IR, DSC, TGA, water retention analysis, and tensile tests. The biodegradability of the acylated protein derivatives has been demonstrated. It can be concluded that the chosen plant proteins are suitable for acylation reactions leading to fusible thermoplastic materials with improved water‐resistance. However, resultant extruded articles possess mostly high brittleness combined with low tensile strength. An improved processability and mechanical performance of the acylated products can be achieved by addition of only 10% glycerol.magnified image
Microcellular Foamed Wood‐Plastic Composites by Different Processes: a Review
Authors: Faruk Omar , Bledzki Andrzej K. , Matuana Laurent M. 
Published: February 2007

AbstractWood fiber reinforced polymer composites represent a relatively small but rapidly growing material class, extensively applied in interior building applications and in the automotive industry. The polymer‐wood fiber composites utilize fibers as reinforcing filler in the polymer matrix and are known to be advantageous over the neat polymers in terms of the materials cost and mechanical properties such as stiffness and strength. Wood fiber reinforced polymer composites are microcellularly processed to create a new class of materials with unique properties. Most manufacturers are evaluating new alternatives of foamed composites that are lighter and more like wood. Foamed wood composites accept screws and nails like wood, more so than their non‐foamed counterparts. They have other advantages such as better surface definition and sharper contours and corners than non‐foamed profiles, which are created by the internal pressure of foaming. This paper represents a review on microcellular wood fiber reinforced polymer composites obtained by different processes (batch, injection molding, extrusion, and compression molding process) and includes an overview of foaming agents (physical and chemical) and the foaming of wood fiber‐polymer composites (changes in phase morphology, formation of polymer‐gas solution, cell nucleation, and cell growth control).magnified image
Microwave‐Promoted Esterification Reactions: Optimization and Scale‐Up
Authors: Amore Kristen M. , Leadbeater Nicholas E. 
Published: February 2007

AbstractMicrowave heating is becoming a widely accepted tool for synthetic chemists. While many reactions have been performed on a small scale using microwave heating, few have been further developed into larger‐scale syntheses. Here, a microwave‐promoted esterification reaction protocol is presented. The apparatus used allows for the removal of water generated during the course of the reaction and as a result the process can be driven toward completion. Reactions have been run on scales up to 3 mol.magnified image
CpG site hypermethylation of E‐cadherin and Connexin26 genes in hepatocellular carcinomas induced by a choline‐deficient L‐Amino Acid‐defined diet in rats
Authors: Tsujiuchi Toshifumi , Shimizu Kyoko , Itsuzaki Yumi , Onishi Mariko , Sugata Eriko , Fujii Hiromasa , Honoki Kanya 
Published: February 2007

AbstractWe investigated DNA methylation patterns of E‐cadherin and Connexin26 (Cx26) genes in rat hepatocellular carcinomas (HCCs) induced by a choline‐deficient L‐Amino Acid‐defined (CDAA) diet. Six‐wks‐old F344 male rats were continuously fed with a CDAA diet for 75 wks, and were then killed. A total of five HCCs were obtained, and genomic DNA was extracted from each HCC for assessment of methylation status in the 5′ upstream regions of E‐cadherin and Cx26 genes by bisulfite sequencing, comparing to two normal liver tissues. The five HCCs showed highly methylated E‐cadherin and Cx26 genes, while these genes in two normal liver tissues were all unmethylated. For analysis of gene expression, real‐time quantitative reverse transcription (RT)‐polymerase chain reaction (PCR) was performed. Expressions of E‐cadherin and Cx26 genes were significantly reduced in the five HCCs (P < 0.0001 and P < 0.001, respectively) compared to normal liver tissues, correlating with their methylation statuses. These results suggested that hypermethylation of E‐cadherin and Cx26 genes may be involved in the development of HCCs induced by a CDAA diet in rats. © 2007 Wiley‐Liss, Inc.
Involvement of Ras/Raf‐1/ERK actions in the magnolol‐induced upregulation of p21 and cell‐cycle arrest in colon cancer cells
Authors: Hsu Yi‐Fan , Lee Tong‐Sheng , Lin Shyr‐Yi , Hsu Sung‐Po , Juan Shu‐Hui , Hsu Yuan‐Hsun , Zhong Wen‐Bin , Lee Wen‐Sen 
Published: February 2007

AbstractPreviously, we showed that magnolol induces cell‐cycle arrest in cultured colon and liver cancer cells through an upregulation of the p21 protein [1]. The aim of this study was to delineate the molecular mechanism underlying this magnolol‐induced increase of p21 protein. Thus our RT‐PCR analysis demonstrated that the mRNA levels of p21 were increased at 1 h after magnolol treatment and sustained for at least 24 h. The p21 promoter activity was also increased by magnolol treatment. Western blot analysis demonstrated that treatment of COLO‐205 cells with magnolol increased the levels of phosphorylation of extracellular signal‐regulated kinase (ERK). Pretreatment of the cells with PD98059 abolished the magnolol‐induced upregulation of p21 protein, suggesting the involvement of an ERK pathway in the magnolol‐induced upregulation of p21 in COLO‐205 cells. Ras inhibitor peptide abolished the magnolol‐induced increase of phosphorylated ERK protein levels, increase of p21 protein, and decrease of thymidine incorporation. Moreover, treatment of COLO‐205 with magnolol increased the phosphorylated Raf‐1 protein (the Ras target molecule). Pretreatment of the cells with Raf‐1 inhibitor reversed the magnolol‐induced decrease in thymidine incorporation. Treatment of the cells with CaM kinase inhibitor, but not protein kinase A (PKA) inhibitor or phosphatidylinosital 3‐kinase (PI3K) inhibitor, abolished the magnolol‐induced activation of ERK and decrease of thymidine incorporation. Taken together, our results suggest that magnolol activates ERK phosphorylation through a Ras/Raf‐1‐mediated pathway. Subsequently, p21 expression is increased, and finally thymidine incorporation is decreased. © 2007 Wiley‐Liss, Inc.
Adenovirus E1A requires c‐Ras for full neoplastic transformation or suppression of differentiation of murine preadipocytes
Authors: Cao J. , Arulanandam R. , Vultur A. , Anagnostopoulou A. , Raptis L. 
Published: February 2007

AbstractWe recently demonstrated that the Adenovirus‐5 E1A gene products (E1A), known E2F activators, can block the differentiation of murine preadipocytes and that differentiation suppression occurs at lower levels than required for full neoplastic transformation. Progressively higher levels were accompanied by apoptosis induction. To examine the role of the cellular Ras protooncogene product (Ras) in E1A function, E1A was expressed in C3H10T½ (10T½)‐derived preadipocytes rendered deficient in Ras activity by transfection with inducible or constitutive antisense ras gene constructs (Ras‐knockdowns). The results showed that, although even low amounts of E1A could block the differentiation of 10T½ preadipocytes with normal Ras levels, even the highest E1A levels were unable to block the differentiation or induce transformation of Ras‐knockdown preadipocytes. Ras downregulation did not affect E2F activation by E1A. Interestingly, our results further demonstrated a dramatic reduction in the levels of the E1A protein itself as differentiation progressed, with a concomitant reduction in E1A's ability to induce apoptosis as a result. These findings suggest for the first time that Ras, although cytoplasmic, is an integral component of the pathway whereby E1A, an oncoprotein believed to have primarily nuclear targets, suppresses differentiation or induces neoplastic conversion of murine preadipocytes. © 2007 Wiley‐Liss, Inc.
2‐amino‐1‐methyl‐6‐phenylimidazo [4,5‐b] pyridine‐induced DNA adducts and genotoxicity in chinese hamster ovary (CHO) cells expressing human CYP1A2 and rapid or slow acetylator N‐acetyltransferase 2
Authors: Metry Kristin J. , Zhao Shuang , Neale Jason R. , Doll Mark A. , States J. Christopher , McGregor W. Glenn , Pierce William M. , Hein David W. 
Published: February 2007

AbstractHeterocyclic amine carcinogens such as 2‐amino‐1‐methyl‐6‐phenylimidazo [4,5‐b] pyridine (PhIP) are present in diet and cigarette smoke. Bioactivation in humans includes N‐hydroxylation catalyzed by cytochrome P4501A2 possibly followed by O‐acetylation catalyzed by N‐acetyltransferase 2 (NAT2). Nucleotide excision repair‐deficient Chinese hamster ovary (CHO) cells were stably transfected with humanCYP1A2and eitherNAT2*4(rapid acetylator) orNAT2*5B(slow acetylator) alleles. CYP1A2 and NAT2 catalytic activities were undetectable in untransfected CHO cell lines. CYP1A2 catalytic activity levels did not differ significantly (P > 0.05) among theCYP1A2‐transfected cell lines. Cells transfected withNAT2*4had significantly higher levels of N‐acetyltransferase (P = 0.0001) and N‐hydroxy‐PhIP O‐acetyltransferase (P = 0.0170) catalytic activity than cells transfected withNAT2*5B. PhIP caused dose‐dependent decreases in cell survival and significant (P < 0.001) increases in mutagenesis measured at thehypoxanthine phosphoribosyl transferase(hprt) locus in all theCYP1A2‐transfected cell lines. Transfection withNAT2*4orNAT2*5Bdid not further increasehprtmutagenesis. PhIP‐inducedhprtmutant cDNAs were sequenced, and 80% of the mutations were single base substitutions at G:C base pairs. dG‐C8‐PhIP DNA adduct levels were dose‐dependent in the order: untransfected < transfected withCYP1A2 < transfected withCYP1A2andNAT2*5B < transfected withCYP1A2andNAT2*4. Following incubation with 1.2 µM PhIP, DNA adduct levels were significantly (P < 0.05) higher in CHO cells transfected withCYP1A2/NAT2*4versusCYP1A2/NAT2*5B. These results strongly support an activation role for CYP1A2 in PhIP‐induced mutagenesis and DNA damage and suggest a modest effect of human NAT2 and its genetic polymorphism on PhIP DNA adduct levels. © 2007 Wiley‐Liss, Inc.