bluuebunny/crossref_metadata_2025 huggingface dataset:
Pre‐Treatment of human osteosarcoma cells with N‐methylformamide enhances P‐glycoprotein expression and resistance to doxorubicin
Authors: Scotlandi Katia , Serra Massimo , Manara Maria Cristina , Lollini Pier‐Luigi , Maurici Daniela , Bufalo Donatella Del , Baldini Nicola
Published: February 2007

N‐methylformamide (NMF), 3 powerful differentiating agent, has been extensively used in experimental and preclinical cancer chemotherapy studies, alone or in association with conventional anti‐cancer drugs. To evaluate the use of this molecule in the treatment of osteosarcoms (OS), we have analyzed the effects of NMF and doxorubicin (DXR) or DXR‐sensitive and ‐resistant human OS cell lines. Our study shows that NMF exerts remarkable effects on cell proliferation and, in Saos‐2 and SARG cells, also induces differentiation, as shown by increasing alkaline phosphatase activity. Moreover, NMF increases the cytotoxic activity of DXR when administered after the drug, In both DXR‐sensitive and ‐resistant cells. However, when this agent is given before DXR, it enhances P‐glycoprotein expression in U‐2 OS cell lines. This over‐expression is associated with reduced DXR accumulation within cells and with significant enhancement of resistance to DXR. © 1994 Wiley‐Liss, Inc.
A novel strategy of C‐myc oncogene in NK activity regulation not related to the W6/32 MHC class‐I epitope
Authors: La Cava Antonio , Carbone Ennio , Moscarella Anna , Barcová Mária , Salzano Salvatore , Zappacosta Serafino , Fontana Silvia
Published: February 2007

The C‐myc gene encodes a nuclear protein whose precise function is still not folly understood. Introduction of a c‐myc gene into a number of cell lines leads to an increase in their susceptibility to NK‐cell lysis. It was reported earlier that c‐myc can induce a decrease in the membrane expression of the MHC class‐1 molecules and this may be one of the factors that render target cells relatively more susceptible to NK lysis. In this contribution, we show, in a human LCL line transfected with a constitutively active c‐myc gene, an increased sensitivity to NK lysis, which correlates with an augmented effector‐target binding ability of c‐myc‐transfected LCLs and with a high 1CAM‐1 expression rather than with down‐regulation of MHC class‐l W6/32 epitope expression. © 1994 Wiley‐Liss, Inc.
Involvement of protein kinase C and an elastase‐like enzyme in the processing of transforming growth factor‐α in human colon carcinoma cell lines
Authors: Levine Alan E.
Published: February 2007

Human colon carcinoma cell lines secrete transforming growth factor‐α (TGF‐α). Previous work indicated that the apparent m.w. of the TGF‐o secreted by these cells ranged between 5 and 25 kDa. The more differentiated GEO cell line secreted a higher percentage of high m.w. TGF‐or than did the poorly differentiated HCT 116 cell line. In addition, the HCT 116 cells secreted 5‐fold more TGF‐a. Treatment of HCT 116 and GEO cells with a phorbol ester (TPA) resulted in a 4‐fold increase in TGF‐α in the conditioned media of both cell types. The TPA‐induced release of TGF‐a was blocked by an inhibitor of elastase‐like enzymes. This suggested a role for protein kinase C (PKC) in TGF‐α processing in colon carcinoma cells. Direct measurement of PKC activity indicated that the HCT 116 cells (which secrete more fully processed TGF‐α) had 10‐fold more PKC activity than GEO cells. The presence of an elastase‐like activity in detergent extracts and the ability of an elastase inhibitor to block the TPA‐induced secretion of TGF‐a suggests that PKC and an elastase‐like enzyme are involved in the processing and secretion of TGF‐a by human colon carcinoma cell lines. © 1994 Wiley‐Liss, Inc.
Cytotoxic and antitumor activity of a recombinant immunotoxin composed of disulfide‐stabilized anti‐TAC Fv fragment and truncated pseudomonas exotoxin
Authors: Reiter Yoram , Kreitman Robert J. , Brinkmann Ulrich , Pastan Ira
Published: February 2007

Disulfide‐stabilized Fv (dsFv)‐immunotoxins are recombinant immunotoxins in which the inherently unstable Fv moiety, composed of the VH‐VL heterodimer, is stabilized by a disulfide bond engineered between structurally conserved framework positions of VH and VL. Anti‐Tac(dsFv)‐PE38KDEL is composed of such a dsFv, directed to the α subunit of the IL2 receptor (IL2R), and containing a truncated form of Pseudomonas exotoxin (PE38KDEL). We have found this new type of immunotoxin to be indistinguishable in its in vitro activity and specificity from its single‐chain immunotoxin counterpart, anti‐Tac(Fv)‐PE38KDEL. We have now examined the therapeutically relevant factors, including stability, pharmacokinetics, and antitumor activity of this new disulfide‐stabilized Fv‐immunotoxin. We found that anti‐Tac(dsFv)‐PE38KDEL was specifically cytotoxic to human activated T‐lymphocytes in addition to IL2R bearing cell lines. Anti‐Tac(dsFv)‐PE38KDEL was considerably more stable at 37° C in human serum and in buffered saline than the single‐chain immunotoxin, anti‐Tac(Fv)‐PE38KDEL. The half‐life in blood was similar for both immunotoxins (approx. 20 min). The therapeutic potential of the disu Hide‐stabilized immunotoxin was evaluated using an animal model of immunodeficient mice bearing subcutaneous tumor xenografts of human IL2R‐bearing cells. Anti‐Tac(dsFv)‐PE38KDEL caused complete regression of tumors with no toxic effects in mice. Because dsFv‐immunotoxins are more stable and can be produced with significantly improved yields compared to scFv‐immunotoxins, dsFv‐immunotoxin may be more useful for therapeutic applications. © 1994 Wiley‐Liss, Inc.
Cutaneous malignant melanoma and exposure to sunlamps or sunbeds: An eortc multicenter case‐control study in Belgium, France and Germany
Authors: Autier Philippe , Doré Jean‐Francois , Lejeune Ferdy , Koelmel Klaus F. , Geffeler Olaf , Hille Petra , Cesarini Jean‐Pierre , Lienard Daniéle , Liabeuf André , Joarlette Marie , Chemaly Philippe , Hakim Karole , Koeln Astrid , Kleeberg Ulrich R. ,   for the EORTC Melanoma Cooperative Group
Published: February 2007

The study objective was to assess whether exposure to sunlamps and sunbeds represents a risk factor for cutaneous malignant melanoma (CMM). A 1‐to‐1 unmatched case‐control study was conducted among subjects 20 years old or more with naturally non‐pigmented skin in Germany, France and Belgium. A total of 420 consecutive patients with CMM diagnosed from I January 1991 onward were derived from hospital registers; 447 controls with no history of skin cancer were chosen at random in the same municipality as the cases. Exposure to sunlamps or sunbeds starting before 1960 is associated with a crude estimated risk of CMM of 2.71 (95% CI: 1.06‐7.78) for at least 10 hr of accumulated exposure. This risk is of 2.12 (95% CI: 0.84‐5.37) after adjustment for age, sex, hair colour and average number of holiday weeks each year in sunny resorts. Subjects who experienced skin‐burn due to sunlamps or sunbeds, and who had accumulated at least 10 hr of exposure, displayed a crude estimated CMM risk of 4.47 (95% CI: 1.45‐13.7), which rose to 8.97 (95% CI: 2.10‐38.6) for those who exposed their skin for tanning purposes. The risk associated with skin‐bum is only marginally modified after multiple adjustments for host characteristics and recreational exposure to sunlight. Apparently, sunlamps and sunbeds share the increased risk of CMM, which seems to concentrate in subjects exhibiting hazardous behaviour towards ultraviolet radiation sources. However, although it is reasonable to believe that high doses of pure ultraviolet A radiation can be dangerous, this is not firmly established by this study. Most exposures to ultraviolet A tanning devices began after 1980; therefore, epidemiologic studies have difficulty in revealing any increase in risk of CMM starting after 1980 because of the latent period between exposure and occurrence of melanoma. Public health authorities should have a cautious approach towards the rapidly developing fashion of tanning under sunlamps or sunbeds.
Insulin‐and insulin‐like growth‐factor‐I receptor tyrosine‐kinase activities in human renal carcinoma
Authors: Kellerer Monika , von Eye Corleta Helena , Mühlhöfer Andreas , Capp Edison , Mosthaf Luitgard , Bock Susanne , Petrides Petro E. , Häring Hans U.
Published: February 2007

We studied expression and functional characteristics of the insulin‐ and insulin‐like‐growth‐factor‐1(IGF‐1) receptors in human renal carcinoma. Ligand‐binding properties and tyrosine‐kinase activity of both receptors, as well as the expression of the 2 isoforms of the human insulin receptor (HIR‐A and ‐B) were analyzed in renal carcinoma and normal adjacent kidney tissue of 8 adult patients. Partially purified insulin‐ and IGF‐I receptors from normal and renal cell carcinoma tissue possessed identical affinities for their ligands. Renal cell carcinoma, however, contained 3‐ to 4‐fold more specific insulin‐binding sites and 2‐fold more IGF‐I binding sites than adjacent normal kidney tissue. In addition, we determined the relative content of insulin/IGF‐I receptor hybrids in both tissues. Renal cell carcinoma and adjacent normal tissue revealed similar amounts of insulin/IGF‐l receptor hybrids, i.e., 44 ± 8.2% of tracer IGF‐I binding in normal tissue and 46 ± 12.0% in renal cell carcinoma. When equal amounts of insulin‐ and IGF‐I receptor protein were studied, we found significantly increased receptor autophos‐ phorylation and elevated substrate phosphorylation in carcinoma tissue. To assess whether the differences in insulin‐receptor tyrosine‐kinase activity were caused by an altered pattern of insulin receptor isoform expression, we determined mRNA levels for HIR‐A and ‐B. The 2 insulin receptor isoforms were, however, expressed in highly variable ratios in both normal and tumor tissue. Our experiments show that renal carcinoma expresses an elevated amount of insulin‐ and IGF‐I receptor protein with increased specific autophosphorylation and tyrosine‐kinase activity each. The increase of insulin‐receptor tyrosine‐kinase activity in renal carcinoma cannot be explained by an altered expression pattern of insulin receptor isoforms. © 1995 Wiley‐Liss, Inc.
Raman spectroscopy of the sampleite group of minerals
Authors: Frost Ray L. , Weier Matt L. , Williams Peter A. , Leverett Peter , Kloprogge J. Theo
Published: February 2007

Raman and infrared spectroscopy enabled insights into the molecular structure of the sampleite group of minerals. These minerals are based upon the incorporation of either phosphate or arsenate with chloride anion into the structure, and as a consequence the spectra reflect the bands attributable to these anions, namely, phosphate or arsenate with chloride. The sampleite vibrational spectrum reflects the spectrum of the phosphate anion and consists of ν1 at 964 cm−1, ν2 at 451 cm−1, ν3 at 1016 and 1088 cm−1 and ν4 at 643, 604, 591 and 557 cm−1. The lavendulan spectrum consists of ν1 at 854 cm−1, ν2 at 345 cm−1, ν3 at 878 cm−1 and ν4 at 545 cm−1. The Raman spectrum of lemanskiite is different from that of lavendulan consistent with a different structure. Low wavenumber bands at 227 and 210 cm−1 may be assigned to CuCl transverse/longitudinal (TO/LO) optic vibrations. Raman spectroscopy identified the substitution of arsenate by phosphate in zdenekite and lavendulan. Copyright © 2007 John Wiley & Sons, Ltd.
A resonance Raman spectroscopic study of the protonation of Disperse Orange 25 in solution and adsorbed on oxide surfaces
Authors: Dines Trevor J. , MacGregor Louise D. , Rochester Colin H.
Published: February 2007

The protonation of Disperse Orange 25 (DO25) in aqueous solution, and upon adsorption on oxide surfaces, was studied by resonance Raman (RR) spectroscopy. The neutral and protonated forms of DO25 were modelled by DFT calculations of the isolated molecules in the gas phase at the B3‐LYP/DZ level, enabling calculation of the vibrational spectra of these species, together with vibrational assignments. RR spectra show that DO25 is physisorbed on the SiO2 surface, but its adsorption on SiO2Al2O3 or H‐mordenite results in protonation. This observation indicates the presence of Brønsted acidic sites on these oxide surfaces with pKa values ⩽2.5. RR studies of the adsorption of DO25 can therefore provide useful information on the nature of surface acidity on oxides, which is complementary to that obtained from other probe molecules. Copyright © 2007 John Wiley & Sons, Ltd.
A simple capillary gel electrophoresis approach for efficient and reproducible DNA separations. Analysis of genetically modified soy and maize
Authors: Sánchez Laura , González Ramón , Crego Antonio L. , Cifuentes Alejandro
Published: February 2007

It is generally assumed that in order to achieve suitable separations of DNA fragments, capillary gel electrophoresis (CGE)‐coated capillaries should be used. In this work, a new method is presented that allows to obtain reproducible CGE separations of DNA fragments using bare fused‐silica capillaries without any previous coating step. The proposed method only requires: (i) a capillary washing with 0.1 M hydrochloric acid between injections and (ii) a running buffer composed of Tris‐phosphate‐ethylenediamine tetraacetic acid (EDTA) and 4.5% of 2‐hydroxyethyl cellulose (HEC) as sieving polymer. The use of this new CGE procedure gives highly resolved and reproducible separations of DNA fragments ranging from 50 to 750 bp. The separation of these DNA fragments is accomplished in less than 30 min with efficiencies up to 1.7×106 plates/m. Reproducibility values of migration times (given as %RSD) for the analyzed DNA fragments are better than 1.0% (n = 4) for the same day, 2.2% (n = 16) for four different days, and 2.3% (n = 16) for four different capillaries. The usefulness of this separation method is demonstrated by detecting genetically modified maize and genetically modified soy after DNA amplification by PCR. This new CGE procedure together with LIF as detector provides sensitive analysis of 0.9% of Bt11 maize, Mon810 maize, and Roundup Ready soy in flours with S/N up to 542. These results demonstrate the usefulness of this procedure to fulfill the European regulation on detection of genetically modified organisms in foods.
Chromatographic and electrophoretic approaches for the analysis of protein quality of soy beverages
Authors: Amigo‐Benavent Miryam , Villamiel Mar , del Castillo M. Dolores
Published: February 2007

Furosine, generated by acid hydrolysis of fructosyllysine, an early Maillard reaction product, is a highly valuable indicator of food quality and, more specifically, of food protein quality. Ion pair RP‐HPLC and CZE techniques were employed to determine furosine content in beverages based on soymilk (n = 15) and cow's milk supplemented with soy isoflavones (n = 1). The levels of furosine found in the samples ranged from 25.55 ± 0.18 to 170.72 ± 10.4 mg/100 g of protein by HPLC and from 28.67 ± 1.84 to 161.25 ± 5.78 mg/100 g of protein by CZE. Results obtained by both analytical techniques do not differ significantly (p >0.05), confirming their feasibility for furosine analysis in soy‐based products.
Modellierung des Fließverhaltens und Beschreibung des duktilen Versagens in einem weiten Bereich von Dehngeschwindigkeiten
Authors: Abdel‐Malek S. , Meyer L. W.
Published: February 2007

Die Beschreibung des Werkstoffverhaltens durch geeignete konstitutive Modelle ist eine wesentliche Grundlage für die Simulation der in der Praxis auftretenden Verformungs‐ und Versagensvorgänge. Dabei ist insbesondere für die Simulation hochgeschwindigkeitsbelasteter Bauteile, wie sie in den ballistischen und Crash‐Vorgängen sowie bei Hochgeschwindigkeitsumformprozessen erfolgen, die Kenntnis von dynamischen Werkstoffkennwerten sowie des Werkstoffverhaltens unter Berücksichtigung der realen Belastungsbedingungen unbedingt erforderlich.

Die Modellierung auf der Grundlage des Konzeptes der thermischen Aktivierung, z. B. durch das MTS‐Modell, führt bei hohen Verformungen und extremen Dehngeschwindigkeiten zu einer sehr guten Übereinstimmung zwischen modelliertem und realem Werkstoffverhalten. Bei niedrigen Geschwindigkeiten bzw. hohen Temperaturen kann durch Einfügen eines zusätzlichen Spannungsanteils der Effekt der dynamischen Reckalterung berücksichtigt und damit der Gültigkeitsbereich des MTS‐Modells erweitert werden.

Im Rahmen der vorliegenden Arbeit wurden bei der Modellierung des Versagensverhaltens die Effekte der Temperatur, der Geschwindigkeit und der Verformungsverfestigung zusätzlich zum Einfluss der Spannungsmehrachsigkeit berücksichtigt. Die Bestimmung des Spannungsmehrachsigkeitsgrades bei der Einschnürung bzw. im Kerbbereich der gekerbten Zugproben bis zur Rissinitiierung erfolgte mittels FE‐Rechnungen. Es konnte gezeigt werden, dass das dynamische Verfestigungsverhalten des Werkstoffes die resultierenden Schädigungskurven stark beeinflusst.
Partially adhesive fixation of reconstruction plates at midfacial fractures – an alternative solution to screw fixation?
Authors: Smeets R. , Riediger D. , Wirtz D. C. , Marx R. , Endres K.
Published: February 2007

For the prognosis and long‐term stability of an implant, for example a hip‐ or knee‐implant, the anchorage to the bone is of critical importance. Normally for this anchorage bone cement is used, which achieves sufficient retention to spongious bone structure. If there is the need for osteosynthesis of midfacial fractures for surgical therapy, in some situations it would be clinically preferable to fix the reconstruction plates without the usual system using screws. This is the aim of the new adhesive fixing technology which is presented in this article. The structure of bone in midface, however, is cortical and such a smooth surface will allow only insufficient retention forces between bone and bone cement. In order to obtain a good adhesion at cortical bone nevertheless, we have to apply a bone bonding agent similar to techniques used in dentistry, which are based on dentin bonding agents, because there are different wetting properties of the hydrophilic bone and the hydrophobic bone cement monomers.

Determination of achievable bond strength was done in a tension test ex vivo. Reconstruction plates were fixed with bone cement at bovine bone conditioned with a bone bonding agent developed for this field of application. With bond strengths up to 6 MPa it is assumed that an adhesive fixation of reconstruction plates at cortical bone structure is possible using the developed amphiphilic bone bonding agent.
Galvanisches Verzinken von Magnesiumlegierungen
Authors: Pokhmurska H. , Wielage B. , Lampke Th. , Zacher M. , Fischer U. , Kwiatkowski L. , Grobelny M.
Published: February 2007

Magnesiumlegierungen sind sehr korrosionsanfällig, was ihre Anwendung unter korrosiven Bedingungen einschränkt. Eine Möglichkeit, um Magnesium vor aggressiven Umweltbedingungen zu schützen, ist das Beschichten. Es werden Ergebnisse über das Korrosionsverhalten der aus verschiedenen Elektrolyten galvanisch verzinkten Magnesiumknetlegierung AZ31 gezeigt. Die Bewertung der Korrosionsprozesse in chloridhaltigen Lösungen erfolgte durch elektrochemische Messungen.

Durch einstündige Auslagerung der beschichteten Proben wurde festgestellt, dass dicke und dichte galvanische Zinkschichten auf AZ31 die Korrosionseigenschaften verbessern. Eine Erhöhung der Immersionszeit führt jedoch zu einer Verschlechterung der Korrosionseigenschaften. Elektrolytische Zinkschichten, die durch einen konsekutiven alkalisch / sauren Prozess erzeugt werden, stabilisieren die Schicht und verbessern somit die Korrosionsbeständigkeit des beschichteten AZ31.
Erhöhung der Verschleißfestigkeit von Elastomerverarbeitungsmaschinen durch innovative Beschichtungsverfahren
Authors: Hartmann U. , Gebert A. , Richter U. , Leonhardt G.
Published: February 2007

Ziel der nachfolgenden Arbeit ist es ausgewählte Oberflächen‐beschichtungsverfahren einer genaueren Bewertung der erreichbaren Verschleißeigenschaften der Schichten in Hinblick auf ihre Eignung für den Verschleißschutz von Elastomerverarbeitungsanlagen (z. B. Innenkneter) zu unterziehen. Dazu wurden Angaben verschiedener Lohnbeschichter zu Aussagen zum Verschleißwiderstand der erzeugten Schichten verglichen. Davon ausgehend wurden eigene experimentelle Untersuchungen zur Schichtherstellung in Hinblick auf den vorgesehenen Einsatzfall durchgeführt und mit Hilfe eines Verschleißtestes auf ihre Schleißeigenschaften bewertet. Neben dem klassischen Auftragschweißen, dem Plasma‐Pulver‐Auftragschweißen, wurden vor allem die innovativen thermochemischen Verfahren angewandt. Besonders wegen ihres ständig steigenden Marktpotenzials, standen speziell das Lichtbogen‐ und Hochgeschwindigkeitsflammspritzen dabei im Vordergrund.
Effects of particulate reinforcement and strain‐rates on deformation and fracture behavior of Aluminum 6061‐T6 under high velocity impact
Authors: Odeshi A. G. , Owolabi G. M. , Nabil Bassim M.
Published: February 2007

Aluminum matrix composites (AMC) exhibit an attractive combination of mechanical and physical properties such as high stiffness and low density, which favors their utilization in many structural applications. Thus, increasing the structural applications of AMC is the driving force for the need to adequately understand their deformation and failure mechanisms under various types of loading conditions. In this study, plastic deformation of alumina particle reinforced Aluminum 6061‐T6 matrix composite is investigated and compared to that of an un‐reinforced Aluminum 6061‐T6 alloy at high strain‐rates under compressive loading. Dynamic stress‐strain curves are obtained using direct impact Split Hopkinson Pressure Bar (SHPB). Particulate reinforcement increases the deformation resistance of the aluminum alloy at high strain‐rates. Strain localization along narrow adiabatic shear bands is observed in both the reinforced and un‐reinforced alloy. Whereas the microstructure of shear bands in un‐reinforced alloy showed finer grain size compared to that of the bulk material, the shear bands observed in the AMCs are darker than the bulk material and the reinforcing particles are observed to be more closely spaced along the shear bands.
Neuartige Faserverbunddrähte für die Leistungselektronik
Authors: Wesling V. , Wilde J. , Knauber A. , Dalin J. , Reiter R.
Published: February 2007

Die Verwendung von leistungselektronischen Komponenten im Rahmen mechatronischer Anwendungen sowie die zunehmende Integration von Bauteilen führen zu gesteigerten Anforderungen an deren mechanische und thermische Beständigkeit. Die Kontaktierung in der Leistungselektronik erfolgt heutzutage großteils mittels Bonden von Aluminium‐Dickdraht. Dieses Verfahren ist hochproduktiv, jedoch ist die Lebensdauer leistungselektronischer Bauelemente mittlerweile überwiegend durch die Haltbarkeit dieser Drahtbondverbindungen begrenzt. Als eine Ursache hierfür ist die thermische Fehlanpassung zwischen dem Drahtwerkstoff und den zu kontaktierenden Bauelementen zu sehen. Ein neuer Ansatzpunkt, um die Zuverlässigkeit zu verbessern, ist der Einsatz neuartiger Faserverbunddrähte mit erhöhter Beständigkeit gegenüber thermo‐mechanischer Beanspruchung.

Im Rahmen eines Forschungsvorhabens wurden Faserverbundbonddrähte unterschiedlicher Materialkombinationen und Anordnungen hergestellt. Aluminiumdrähte mit Kupferfaserverstärkung sowie Kupferdrähte mit FeNi36‐Faserverstärkung konnten erfolgreich auf einen Enddurchmesser von 300 μm gezogen werden. Die Faserverstärkungen sollen den thermischen Ausdehnungskoeffizienten verringern und die mechanische Festigkeit verbessern. Bei Aluminium‐Kupferfaserverbunden wird darüber hinaus die elektrische Leitfähigkeit erhöht. Messungen an den erzeugten Faserverbunddrähten bestätigten diese Erwartungen. Die Herstellung der Faserverbunde erfolgte ausgehend von Drahtmaterial unterschiedlichen Durchmessers. Diese Drähte wurden in Kapseln in verschiedenen Anordnungen und Werkstoffkombinationen gestapelt. Anschließend wurden die Kapseln entweder erst heißisostatisch gepresst oder direkt stranggepresst. Die so erzeugten Verbunde konnten durch Rundkneten und Drahtziehen zu Bonddrähten weiterverarbeitet und erprobt werden.
Herstellung und Umformverhalten austenitischer Polymerkernsandwichverbunde
Authors: Palkowski H. , Lange G.
Published: February 2007

Dreischichtige, symmetrische Sandwichverbunde bieten aufgrund ihres strukturellen Aufbaus und ihres guten Dämpfungsverhaltens bei gleichzeitig hoher Festigkeit ein großes Leichtbaupotenzial. Durch die Kombinierbarkeit der Eigenschaften der Verbundpartner bieten sich Sandwichverbunde als gute Lösung an, wenn es um hohe Festigkeit bei guter Steifigkeit im Leichtbau geht. Je nach funktioneller Anforderung kommen dabei verschiedenste Werkstoffe – Metalle, Polymere u. a. – als Deck‐ und Kernwerkstoffe zum Einsatz. Ein zentrales Problem bei der Konstruktion, der Verarbeitung und dem späteren Einsatz von Sandwichsystemen ist die, im Vergleich zu den monolithischen Werkstoffen, schlechte Umformbarkeit der Verbundpartner mit stark unterschiedlichen E‐Moduli sowie die Frage der Haftung der verschiedenen Materialschichten. Das ist ein Grund, warum der großindustrielle Einsatz solcher Sandwichverbunde derzeit noch eingeschränkt ist.

Im Rahmen des durch die DFG geförderten Projektes „Untersuchungen zur Kompatibilisierungsmethode ”︁Umformen„ für unterschiedliche Metall ‐ Nichtmetall – Systeme”︁ wurden dreischichtige, symmetrische Sandwichverbunde gefertigt und anschließend auf ihre Eigenschaften bezüglich der Haftfestigkeit der Verbundpartner und des Umformverhaltens untersucht.

Die Aufgabe bestand in der Entwicklung, Herstellung und Untersuchung neuer Sandwichwerkstoffe, die hinsichtlich ihrer Funktion und ihres Einsatzes bedarfsgerecht angepasst werden können. Erst die kombinierte Betrachtung der stofflichen und konstruktiven Komponenten führt zu systemorientierten Werkstoffen, Bauteil‐konzepten und ‐strukturen.

Ausgehend von einer industriell ähnlichen Sandwichfertigung im Labormaßstab (Druck‐Fügeverfahren) wurde ein Pressverfahren für Sandwichverbunde entwickelt. Im Druck‐Fügeverfahren konnten zu Beginn des Projektes industrielle Polymerfolien als Kernwerkstoffe, im neu entwickelten Pressverfahren unterschiedliche Polymere in Granulatform als Kernwerkstoff verarbeitet werden. Es kamen dabei faserverstärkte Polyamid‐ und Polypropylengranulate zum Einsatz. Als Deckbleche wurden Edelstahlbleche der Qualität 1.4404 und Aluminiumbleche AlMg3 benutzt. Je nach Herstellungsverfahren wurde für die Polymerfolie ein Epoxidharzkleber bzw. für die Polymergranulate drei verschiedene Haftvermittler eingesetzt. Eine reproduzierbare Fertigung konnte durch den Winkelschälversuch nachgewiesen werden. Die Streck‐ und Tiefzieheigenschaften der Sandwichverbunde in Abhängigkeit von den Kernschichten konnten u. a. im Erichsen‐Tiefungsversuch und in ersten Tiefziehuntersuchungen aufgezeigt werden. So konnte durch faserverstärkte Polymergranulate der E‐Modul im Vergleich zur Polymerfolie erhöht werden. Damit war es möglich, das Tiefziehverhalten deutlich zu verändern.
Magnesium – der Zukunftswerkstoff für die Automobilindustrie?
Authors: Dieringa H. , Kainer K. U.
Published: February 2007

Magnesiumlegierungen weisen ein sehr hohes Potential für den Einsatz als metallischen Konstruktionswerkstoff für die Automobilindustrie auf, wobei der Anwendungsschwerpunkt bei Druckgussbauteilen liegt. Neben der Automobilindustrie ist die Elektroniksparte der wichtigste Abnehmer für Druckgussteile aus Magnesiumlegierungen. Raumtemperaturanwendungen wie z. B. Lenkräder und Rahmenteile im Automobil oder Handy‐ und Notebookgehäuse sind industriell gut eingeführt. Sie werden aus Magnesiumlegierungen der AZ‐ oder AM‐Familie gegossen, die mit ihren guten Raumtemperatureigenschaften und der guten Giessbarkeit die Anforderungen der Industrie seit langem befriedigen. Magnesiumlegierungen, die auch bei erhöhten Temperaturen eingesetzt werden können, stellen die derzeit größten Herausforderungen im Bereich der Legierungsentwicklung für Gussanwendungen dar. Der Einsatz im Antriebsstrang eines Automobils gilt hierbei als Benchmark. Im Bereich des Magnesiumgusses findet die Weiterentwicklung jedoch nicht nur im Bereich der Legierungsentwicklung, sondern auch auf der Verfahrensseite statt. Semi‐Solid‐Verfahren, wie das New‐Rheocasting (NRC), das Thixomolding (TM) oder das Thixocasting (TC) werden an die Erfordernisse der zu verarbeitenden Magnesiumlegierungen angepasst. Neben dem Gussbereich ist das Interesse in den letzten Jahren verstärkt auf magnesiumbasierte Knetlegierungen gefallen. Notwendig sind hier auf der einen Seite Legierungsentwicklung, um die Umformbarkeit und die Mikrostruktur zu verbessern und auf der anderen Seite Weiterentwicklungen der Pozesstechnik auf den Gebieten Strangpress‐ und Walztechnologien, um optimale Parameter für die wegen der hexagonalen Gitterstruktur der Magnesiumlegierungen schwierigen Umformbedingungen zu schaffen.
PVD‐Nanocomposite‐Beschichtungen für die Zerspanungs‐ und Umformtechnik
Authors: Reich S. , Schadewald M. , Bornemann M.
Published: February 2007

Physikalisch und chemisch abgeschiedene Verschleißschutzschichten weisen zunehmend komplexere Strukturen auf. Analog zur Einwicklung kompakter Materialien entstehen auch hier vermehrt Lösungen als Verbundwerkstoffe, welche in Form von Nanocomposites angeboten werden. Eine industriell verfügbare Lösung stellt das System MeN/Si3N4 dar. Dieses soll bezüglich seiner Eigenschaften sowie seiner Einsatzmöglichkeiten im Bereich der Zerspanungs‐ und Umformtechnik vorgestellt werden.
Abscheidung von Palladium und Palladiumlegierungen mit hohen Schichtdicken für die Mikrosystemtechnik
Authors: Günther E. , Jakob C. , Kutzschbach P. , Mache T.
Published: February 2007

Die Abscheidung von Metallen und Legierungen in Mikrostrukturen erfordert meist eine Schichtdicke größer als 100 μm, die der Strukturhöhe entspricht. Für die Nutzung von Edelmetallen in Mikrosystemen ist die Abscheidung von spannungsarmen, rissfreien, porenfreien und duktilen Schichten notwendig. Da die kommerziell abgeschiedenen Edelmetallschichten nur bis etwa 10 μm qualitätsgerecht abgeschieden werden können, sind geeignete Zusätze und Variation der Abscheidungsbedingungen erforderlich, um mikrosystemtaugliche Elektrolyte zu entwickeln. Charakterisierung der Schichteigenschaften, Parameter der Abscheidungstechnologie und Anwendungsbeispiele werden aufgeführt. Erste Ergebnisse werden vorgestellt und diskutiert.
Virtuelles Werkstoff‐ und Prozessdesign funktionaler Schichten
Authors: Wilden J.
Published: February 2007

Heute verfügbare Beschichtungsverfahren, wie das Thermische Spritzen oder auch das Plasma‐Pulver‐Auftragschweißen werden heute vorrangig zur Verbesserung der Korrosions‐ und Abrasionsbeständigkeit von Bauteilen eingesetzt. Eine Erweiterung der Anwendungsgrenzen ist möglich, wenn es gelingt, die Struktur der Schicht gezielt an das jeweilige Anforderungsprofil anzupassen. Gleichzeitig ist darauf zu achten, dass bei einer hohen Prozesseffizienz und Flexibilität des Beschichtungsprozesses eine gleich bleibend hohe Schichtgüte erzielt wird.

Die Modellierung von Beschichtungsprozessen erlaubt es, Zusammenhänge zwischen den Prozessparametern und der Gefügestruktur mit einem Minimum an experimentellen Untersuchungen zu erarbeiten. Ebenso wird es möglich, die Schichtqualität und die Prozesseffizienz gezielt zu steigern und somit durch Veränderung der Prozesskenngrößen eine gezielte Beeinflussung des sich ausbildenden Gefüges zu erreichen. Am Beispiel der Modellierung thermischer Spritzprozesse, insbesondere des Lichtbogenspritzens und des Vakuumplasmaspritzens wird erläutert, welchen Einfluss Veränderungen der Prozessparameter auf die einzelnen, beim thermischen Spritzen ablaufenden Prozesse ausüben. Berücksichtigt wird die Gasströmung, das Aufheizen, Aufschmelzen und Beschleunigen des Spritzwerkstoffs. Von Bedeutung für die Gefügeausbildung ist aber auch die Ausbreitung der einzelnen Spritzpartikel auf dem Substrat, die Schichtbildung durch Überlagerung vieler Partikel und die Erstarrung. Systematische Untersuchungen belegen den Einfluss der Prozessparameter auf die Partikeleigenschaften, die Abkühlung und Erstarrung und damit auf das Gefüge.
Optimization of Dielectric Properties of Suspension Plasma Sprayed Hydroxyapatite Coatings
Authors: Jaworski R. , Pierlot C. , Tomaszek R. , Pawlowski L. , Znamirowski Z. , Zdanowski J.
Published: February 2007

Conventional plasma torch was adapted to spray very fine Ca5 (PO4)3OH (hydroxyapatite, HA) precursors having sizes ranging from a few hundreds of nanometers to a few micrometers. The powders were put in suspension with distilled water and antidispersive agent. A home made suspension feeder, including two peristaltic pumps, delivered the suspension into atomizer and therefrom injected into plasma jet. The suspension flow rate was electronically controlled. The resulting coatings had the thickness of a few tenths of μm. The electrical properties of the coatings including breakdown voltage and loss factor of suspension sprayed hydroxyapatite coatings sprayed onto aluminium substrates were also tested. The influence of such experimental factors as power input to plasma, pressure of atomizing gas, spray distance and suspension feed rate on the responses being the electrical properties was investigated using a 24 design of experiments (DOE). The mathematical models relating the responses with the factors were created and the significant factors were selected.
Maillard reaction indicators in diets usually consumed by adolescent population
Authors: Delgado‐Andrade Cristina , Seiquer Isabel , Navarro M. Pilar , Morales Francisco J.
Published: February 2007

Contents of some indicators of the Maillard reaction (MR) in two diets adjusted to the adolescent requirements are compared: the A‐diet, usually consumed by the adolescent population containing their preferred foods cooked by the culinary techniques more frequently chosen; and the B‐diet, with the same foods, except those industrially processed and with high content of Maillard reaction products (MRP), cooked in softer processes to minimise the MR. Aliquots of a lunch‐dinner (LD) and breakfast‐afternoon (BA) snack pools separately from both diets were ground and lyophilised. Fluorescence associated to MRP, CIELAB colour parameters, furosine, hydroxymethylfurfural (HMF), carboxymethyllysine (CML) and sugar contents were investigated in the samples. Significant losses of lightness were manifested in A samples compared to the B ones. Fluorescence intensity was significantly higher in the LD and BA samples from the A‐diet. Furosine measured in the A‐diet was similar to that found in the B‐diet. However, HMF content was significantly higher in the A‐diet, as well as CML. Data showed significant higher levels of advanced MRP in the usual diet. Thus, MRP intake associated to alimentary pattern in the adolescence population might be studied in order to assess the health implications of the MRP consumption and its possible synergic effect with endogenous advanced glycation endproducts.
Urinary 2‐ethyl‐3‐oxohexanoic acid as major metabolite of orally administered 2‐ethylhexanoic acid in human
Authors: Stingel Dana , Feldmeier Peter , Richling Elke , Kempf Michael , Elss Sandra , Labib Samira , Schreier Peter
Published: February 2007

Human metabolism of 2‐ethylhexanoic acid (2‐EHA), which is a known metabolite of important phthalates, was investigated using 2‐EHA‐contaminated food. The results of our studies reveal that the major catabolic pathway of 2‐EHA in human is β‐oxidation. The dominant final urinary metabolite was identified and quantified as 3‐oxo‐2‐ethylhexanoic acid (3‐oxo‐2‐EHA), but only after immediate methylation of the extract from urine and prior to GC‐MS analysis. Former studies without the precaution of immediate methylation had found 4‐heptanone as the major metabolite, which is obviously an artifact arising from the decarboxylation of 3‐oxo‐2‐EHA.
Optimized techniques for the extraction of grape allergens appropriate for in vivo and in vitro testing and diagnosis
Authors: Vassilopoulou Emilia V. , Zuidmeer Laurian , Akkerdaas Jaap , Rigby Neil , Moreno F. Javier , Papadopoulos Nikolaos G. , Saxoni‐Papageorgiou Photini , Mills Clare , van Ree Ronald
Published: February 2007

Standardized allergen extracts are needed for diagnosis and therapy purposes. For grapes, standardization is hampered by low protein and high tannin and pectin concentrations. The aim of the current study was to develop an optimized method for the extraction of grape proteins and possibly extend this to other fruits. Several existing or modified extraction methods were compared by means of protein concentration determination, SDS‐PAGE, immunoblotting and radioallergosorbent test (RAST). An optimized extraction protocol was obtained in which we combined a high concentration of plant tissue, a concentrated, enriched and neutral buffer able to remove sugars and keep proteins soluble and a bivalent buffer for pectin removal. Both the quantitative (protein concentration) and qualitative parameters (SDS‐PAGE protein patterns and IgE reactivity) were compared to standard protocols and commercial extracts used as diagnostic tools in the clinical practice. This method proved to be the most efficient mainly compared to the standard Björksten protocol in extracting the low molecular weight proteins, including the major grape allergen (lipid transfer protein, Vit v 1). It proved to be an easy, low cost and reproducible method proposed to prepare grape extracts that could replace the commercially available ones, used for diagnosis and possibly extend the method to other fruits especially in extracting LTPs.
NMR spectral assignments of a new chlorotryptamine alkaloid and its analogues from Acacia confusa
Authors: Buchanan Malcolm S. , Carroll Anthony R. , Pass David , Quinn Ronald J.
Published: February 2007

A new chlorotryptamine alkaloid, N‐chloromethyl‐N,N‐dimethyltryptamine, was isolated from a methanol extract of the Chinese shrub Acacia confusa Merr., together with its known hallucinogenic analogues, N‐methyltryptamine, N,N‐dimethyltryptamine and N,N‐dimethyltryptamine‐N‐oxide. The new compound was an artefact of the isolation conditions. The complete 1H and 13C NMR assignments for these compounds were carried out using 1H, 13C, DEPT, gCOSY, gHSQC and gHMBC NMR experiments. Copyright © 2007 John Wiley & Sons, Ltd.
SESAME‐HSQC for simultaneous measurement of NH and CH scalar and residual dipolar couplings
Authors: Würtz Peter , Permi Perttu
Published: February 2007

We present a novel pulse sequence, SESAME‐HSQC, for the simultaneous measurement of several NH and CH scalar and residual dipolar couplings in double labeled proteins. The proposed Spin‐statE Selective All Multiplicity Edited (SESAME)‐HSQC combines gradient selected and sensitivity enhanced 15N‐ and constant‐time 13C‐HSQC experiments with the recently introduced spin‐state selective method (Nolis et al., J. Magn. Reson. 180 (2006) 39–50) for measuring couplings simultaneously at amide and aliphatic regions. Excellent resolution and high sensitivity is warranted by removing all coupling interactions during the indirectly detected t1 period, and by employing pulsed field gradients for coherence selection and utilizing coherence order selective spin‐state selection. The scalar and residual dipolar couplings can be readily measured from a two‐dimensional 15N/13C‐HSQC spectrum without additional spectral crowding. SESAME‐HSQC can be used for epitope mapping by observing chemical shift changes in both amide and aliphatic regions. Simultaneously, potential conversion in protein conformation can be probed by analyzing changes in residual dipolar couplings induced by ligand binding. The pulse sequence is experimentally verified with a sample of 15N/13C enriched human ubiquitin. The internuclear vector directions determined from the residual dipolar couplings are found to be in excellent correlation with those predicted from ubiquitin's refined solution structure. Copyright © 2007 John Wiley & Sons, Ltd.
Comparison of 2‐D LC and 3‐D LC with post‐ and pre‐tryptic‐digestion SEC fractionation for proteome analysis of normal human liver tissue
Authors: Zhang Jie , Xu Xiuqing , Gao Mingxia , Yang Pengyuan , Zhang Xiangmin
Published: February 2007

The current “shotgun” proteomic analysis, strong cation exchange‐RPLC‐MS/MS system, is a widely used method for proteome research. Currently, it is not suitable for complicated protein sample analysis, like mammal tissues or cells. To increase the protein identification confidence and number, an additional separation dimension for sample fractionation is necessary to be coupled prior to current multi‐dimensional protein identification technology (MudPIT). In this work, SEC was elaborately selected and applied for sample prefractionation in consideration of its non‐bias against sample and variety of choice of mobile phases. The analysis of the global lysate of normal human liver tissue sample provided by the China Human Liver Proteome Project, were performed to compare the proteome coverage, sequence coverage (peptide per protein identification) and protein identification efficiency in MudPIT, 3‐D LC‐MS/MS identification strategy with preproteolytic and postproteolytic fractionation. It was demonstrated that 3‐D LC‐MS/MS utilizing protein level fractionation was the most effective method. A MASCOT search using the MS/MS results acquired by QSTARXL identified 1622 proteins from 3‐D LC‐MS/MS identification approaches. A primary analysis on molecular weight, pI and grand average hydrophobicity value distribution of the identified proteins in different approaches was made to further evaluate the 3‐D LC‐MS/MS analysis strategy.
Proteomic analysis of SET‐binding proteins
Authors: Vera Jorge , Estanyol Josep M. , Canela Nuria , Llorens Franc , Agell Neus , Itarte Emilio , Bachs Oriol , Jaumot Montserrat
Published: February 2007

The protein SET is involved in essential cell processes such as chromatin remodeling, apoptosis and cell cycle progression. It also plays a critical role in cell transformation and tumorogenesis. With the aim to study new SET functions we have developed a system to identify SET‐binding proteins by combining affinity chromatography, MS, and functional studies. We prepared SET affinity chromatography columns by coupling the protein to activated Sepharose 4B. The proteins from mouse liver lysates that bind to the SET affinity columns were resolved with 2‐DE and identified by MS using a MALDI‐TOF. This experimental approach allowed the recognition of a number of SET‐binding proteins which have been classified in functional clusters. The identification of four of these proteins (CK2, eIF2α, glycogen phosphorylase (GP), and TCP1‐β) was confirmed by Western blotting and their in vivo interactions with SET were demonstrated by immunoprecipitation. Functional experiments revealed that SET is a substrate of CK2 in vitro and that SET interacts with the active form of GP but not with its inactive form. These data confirm this proteomic approach as a useful tool for identifying new protein–protein interactions.
Design of atto‐vial based recombinant antibody arrays combined with a planar wave‐guide detection system
Authors: Ghatnekar‐Nilsson Sara , Dexlin Linda , Wingren Christer , Montelius Lars , Borrebaeck Carl A. K.
Published: February 2007

Antibody microarray is a rapidly emerging, powerful approach with great promise within high‐throughput proteomics. However, before a truly proteome‐wide analysis can be performed, the antibody array format needs to be miniaturized even further in order to enable ultradense arrays to be fabricated. To this end, we have designed and generated proof‐of‐concept for the first generation of an atto‐vial based recombinant antibody array platform. Briefly, we have designed a novel nanostructured substrate using electron beam lithography. Vials, ranging in volume/size from 6 (200 nm in diameter) to 4000 aL (5 μm in diameter), were fabricated. Human recombinant single‐chain Fv antibody fragments, microarray adopted by design, were used as probes. The set‐up was interfaced with planar wave‐guide technology for evanescant field fluorescence detection. The results showed that protein analytes could be specifically detected in the subzeptomole range for pure systems, using vials down to 57 aL. Further, low‐abundant (pg/mL) protein analytes could be detected in directly labeled complex proteomes, such as human whole serum, using 157 aL‐vials. Taken together, these results outline the potential of the atto‐vial array set‐up for miniaturized affinity proteomics‐based approaches.
Ruthenium (II) tris‐bathophenanthroline disulfonate is well suitable for Tris‐Glycine PAGE but not for Bis‐Tris gels
Authors: Moebius Jan , Denker Katrin , Sickmann Albert
Published: February 2007

Pre‐cast bis(2‐hydroxyethyl)iminotris(hydroxymethyl)methane (Bis‐Tris) gels have proven to be very suitable for pre‐fractionation for LC‐MS/MS analysis due to high reliability and long stability. To visualize proteins within gels fluorescence dyes proved to be a good tradeoff between sensitivity and MS‐compatibility. The custom‐made ruthenium dye represents a low‐cost alternative regarding fluorescence‐based protein visualization with high sensitivity. We demonstrate, that this dye is incompatible with Bis‐Tris gels, while using Tris‐Glycine gels a competitive sensitivity to commercially available stains can be achieved.
Improved comparative proteome analysis based on two‐dimensional gel electrophoresis
Authors: Eravci Murat , Fuxius Sandra , Broedel Oliver , Weist Stephanie , Eravci Selda , Mansmann Ulrich , Schluter Hartmut , Tiemann Joachim , Baumgartner Andreas
Published: February 2007

The purpose of this study was to test the extent to which differences in spot intensity can be reliably recognized between two groups of two‐dimensional electrophoresis gels (pH 4–7, visualized with ruthenium fluorescent stain) each loaded with different amounts of protein from rat brain (power analysis). Initial experiments yielded only unsatisfactory results: 546 spots were matched from two groups of 6 gels each loaded with 200 µg and 250 µg protein, respectively. Only 72 spots were higher (p<0.05), while 58 spots were significantly lower in the 250‐µg group. The construction of new apparatuses that allowed the simultaneous processing of 24 gels throughout all steps between rehydration and staining procedure considerably lowered the between‐gel variation. This resulted in the detection of significant differences in spot intensities in 77–90% of all matched spots on gel groups with a 25% difference in protein load. This applied both when protein from 24 biological replicates was loaded onto two groups of 12 gels and when two pooled tissue samples were each loaded onto 6 gels. At a difference of 50% in protein load, more than 90% of all spots differed significantly between two experimental groups.
Automation of nanoflow liquid chromatography‐tandem mass spectrometry for proteome analysis by using a strong cation exchange trap column
Authors: Jiang Xiaogang , Feng Shun , Tian Ruijun , Han Guanghui , Jiang Xinning , Ye Mingliang , Zou Hanfa
Published: February 2007

An approach was developed to automate sample introduction for nanoflow LC‐MS/MS (μLC‐MS/MS) analysis using a strong cation exchange (SCX) trap column. The system consisted of a 100 μm id×2 cm SCX trap column and a 75 μm id×12 cm C18 RP analytical column. During the sample loading step, the flow passing through the SCX trap column was directed to waste for loading a large volume of sample at high flow rate. Then the peptides bound on the SCX trap column were eluted onto the RP analytical column by a high salt buffer followed by RP chromatographic separation of the peptides at nanoliter flow rate. It was observed that higher performance of separation could be achieved with the system using SCX trap column than with the system using C18 trap column. The high proteomic coverage using this approach was demonstrated in the analysis of tryptic digest of BSA and yeast cell lysate. In addition, this system was also applied to two‐dimensional separation of tryptic digest of human hepatocellular carcinoma cell line SMMC‐7721 for large scale proteome analysis. This system was fully automated and required minimum changes on current μLC‐MS/MS system. This system represented a promising platform for routine proteome analysis.