bluuebunny/crossref_metadata_2025 huggingface dataset:
Absence of histologic evidence of synovitis in patients with Gulf War veterans' illness with joint pain
Authors: Diaz‐Torne C. , Schumacher H. R. , Yu X. , Gomez‐Vaquero C. , Dai L. , Chen L. X. , Clayburne G. , Einhorn E. , Sachdeva R. M. , Singh J. A. , Pessler F.
Published: September 2007

Objective

An unexplained multisymptom illness, Gulf War veterans' illness (GWVI), has been described among allied force veterans of the first Gulf War (1990–1991). It has been proposed that some of its symptoms reflect an immune dysfunction, and rheumatologic symptoms including joint pain and stiffness are reported frequently. However, it is unknown whether synovial inflammation causes the articular symptoms. We examined synovial tissue from individuals with GWVI and joint pain for evidence of inflammation.

Methods

We compared synovial biopsy samples from 6 individuals with GWVI and joint pain with samples from 9 clinically asymptomatic controls (hematoxylin and eosin [H&E] stains only) and biopsy samples or surgically obtained specimens from 10 patients with rheumatoid arthritis (RA) and 12 with osteoarthritis (OA). Inflammatory changes were quantified in H&E stained sections with a modified synovitis score by immunostaining for CD3, CD20, CD38, CD68, Ki‐67, and von Willebrand factor, and with a composite inflammation score based on these markers.

Results

Normal histology was seen in the GWVI specimens, except for mild focal lining hyperplasia and rare low‐grade perivascular infiltrates in 1 specimen each. Mean ± SEM synovitis scores were lowest and nearly identical in control (1.38 ± 0.30) and GWVI specimens (1.41 ± 0.29), intermediate in OA specimens (2.64 ± 0.39), and highest in RA specimens (6.0 ± 0.19). Likewise, inflammatory cells, cell division, vascular density, and composite inflammation score were lowest in the GWVI specimens.

Conclusion

Despite significant joint pain, the GWVI synovia did not differ from normal controls. These results agree with other studies that have failed to document inflammatory or immunologic etiologies in GWVI.
Improving osteoarthritis detection in the community: Pharmacist identification of new, diagnostically confirmed osteoarthritis
Authors: Marra Carlo A. , Cibere Jolanda , Tsuyuki Ross T. , Soon Judith A. , Esdaile John M. , Gastonguay Louise , Oteng Bridgette , Embley Patrick , Colley Lindsey , Enenajor Gilbert , Kok Roelof
Published: September 2007

Objective

Osteoarthritis (OA) is the most common arthritis and a leading cause of disability. Many persons with knee OA are not diagnosed and not referred for treatment. Therefore, identification of patients with knee pain who have undiagnosed OA needs to be improved. Our objective was to determine if pharmacists, using a simple screening questionnaire, can identify individuals with previously undiagnosed knee OA.

Methods

Patients with knee pain and no previous diagnosis of knee OA were recruited by community pharmacists who used a simple questionnaire (<10 minutes to complete) to determine likelihood of knee OA. Patients who were likely to have knee OA were referred for a standardized knee examination and radiograph.

Results

Of the 411 patients screened by pharmacists, 274 were eligible. Of these, 44 declined, 35 were ineligible (18 had a previous OA diagnosis,16 had other inflammatory conditions, and 1 was excluded for other reasons), and 1 died. The remaining 194 were mostly female (62%) with a mean age of 62 years and were mostly white (86%). Body mass index (BMI) was classified as normal (18.5–24.9 kg/m2) in 29%, overweight (25.0–29.9 kg/m2) in 45%, and obese (>30.0 kg/m2) in 26%. Of those examined, 190 (98%) of 194 met the American College of Rheumatology clinical criteria for knee OA. The radiographic results revealed that most participants likely had mild OA.

Conclusion

Pharmacists administering a simple screening questionnaire can identify >80% of patients with knee pain who have undiagnosed knee OA. Based on radiographs and BMI, much of this OA is early and may be amenable to intervention.
The relationship of the posterior inferior cerebellar artery to cranial nerves VII–XII
Authors: Saylam C. , Ucerler H. , Orhan M. , Cagli S. , Zileli M.
Published: September 2007

The posterior inferior cerebellar artery (PICA) is the largest branch of the vertebral artery. It usually arises at the anterolateral margin of the medulla oblongata close to the lower cranial nerves. The PICA had the most complex relationship to the cranial nerves of any artery and it is frequently exposed in approaches directed to the fourth ventricle. The aim of this article is to describe the anatomical relationship of the PICA to the lower cranial nerves. In this study, 12.5% of PICAs passed between the glossopharyngeal and vagus nerves, 20% between the vagus and accessory nerves, and 65% through the rootlets of the accessory nerve. The lateral medullary segment of the PICA showed a lateral loop which in 20% specimens pressed against the inferior surfaces of the facial and vestibulocochlear nerves. The lateral medullary segment of the PICA in 20% specimens passed superior to the hypoglossal nerve, in 47.5% through the rootlets of the hypoglossal nerve, and in 30% inferior to the hypoglossal nerve. The findings on the relationship of the PICA to the lower cranial nerves could be helpful in microsurgery of this region. Clin. Anat. 20:886–891, 2007. © 2007 Wiley‐Liss, Inc.
The superficial ulnar artery: Incidence and calibre in 95 cadaveric specimens
Authors: Dartnell J. , Sekaran P. , Ellis H.
Published: September 2007

The superficial ulnar artery (SUA) is an anatomical variation of the upper limb vasculature with a prevalence of 0.7–9.4% in the population. The importance of this variant is that it may be cannulated inadvertently by an unsuspecting physician, leading to possible ischemia of the hand. With the growing use of radial forearm flaps, the surgeon needs to be aware of its presence during surgery and be able to adapt the procedure accordingly. The aims of the study focus on the incidence and calibre of the SUA. Ninety‐five cadaveric limbs were dissected and the calibre of the different arteries measured. Four SUAs (4.2%) were found, all in male cadavers. Two of these were from the same cadaver. Measurements of the calibre of the vessels showed that the SUA was smaller than the ulnar artery. Of the limbs dissected, 4.2% had an SUA, which is a similar prevalence to other studies in Western Europe. It is most commonly found in males, unilaterally and in the right upper limb. It is extremely rare to experience consequences from intra‐arterial cannulation and the SUA may have more of a beneficial role in reconstructive fasciocutaneous forearm flaps. Clin. Anat. 20:929–932, 2007. © 2007 Wiley‐Liss, Inc.
CFD Simulation of Flow Distribution in the Header of Plate‐Fin Heat Exchangers
Authors: Wasewar K. L. , Hargunani S. , Atluri P. , Naveen K.
Published: September 2007

The flow distribution through a plate‐fin heat exchanger is studied by using a computational fluid dynamics (CFD) code, FLUENT. The flow distribution through any heat exchanger affects its performance. In designing a heat exchanger, it is assumed that the fluid is uniformly distributed through the heat exchanger core. In practice, however, it is impossible to distribute fluid uniformly, because of an improper inlet configuration, imperfect design, and a complex heat transfer process. The CFD simulation of the flow distribution in the header of a conventional plate‐fin heat exchanger is presented. It is found that the flow maldistribution is very serious in the y‐direction of the header. A modified header is proposed and simulated using CFD. The modified header configuration has a more uniform flow distribution than the conventional header configuration. Hence, the efficiency of the modified heat exchanger is seen to be higher than that of the conventional heat exchanger.
Properties of BaAl2O4 in the Simultaneous Removal of Soot and NOx
Authors: Li Y.‐J. , Lin H. , Shangguan W.‐F. , Huang Z.
Published: September 2007

The catalytic activity of BaAl2O4 in the simultaneous removal of soot and NOx was evaluated by Temperature Programmed Reaction (TPR). It was found that BaAl2O4 could effectively catalyze the reaction of soot with NOx under various reaction conditions. Compared with non‐catalytic combustion, ignition temperature, Tig, and maximum combustion temperature, Tm, of soot decreased by more than 175 °C and 240 °C, respectively. Tight contact of soot with BaAl2O4, higher O2 content and a lower flow rate of synthesized gases were beneficial to the catalytic reaction. It was confirmed by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analysis, that the reaction of soot with NO2(ad) was the most important factor in simultaneous removal of soot and NOx, in which NO2(ad) existed on BaAl2O4 in the form of monodentate nitrate, bridged nitrate and ionic nitrate.
Numerical Calculations of Spray Roasting Reactors of the Steel Industry with Special Emphasis on Fe2O3‐Particle Formation
Authors: Beck M. , Wirtz S. , Scherer V. , Bärhold F.
Published: September 2007

This work presents numerical calculations for the lay‐out of spray roasting reactors for the steel industry. In these reactors, a pickling liquor based on water and HCl containing FeCl2 is regenerated in a combustor leading to the formation of Fe2O3 particles. For the lay‐out of these reactors, detailed knowledge of the flow and temperature field, the associated gas phase reactions, and especially, of the formation of the Fe2O3 particles is required. An extended particle formation model is presented which is based on earlier work. Finally, results for an industrial spray roasting reactor are given showing the potential of the numerical tools developed for the improvement of the technical lay‐out of such thermal reactors.
The Progression of Synthetic Strategies to Assemble Titanium Complexes Bearing the Terminal Imide Group
Authors: Fout Alison R. , Kilgore Uriah J. , Mindiola Daniel J.
Published: September 2007

The synthesis of terminal titanium imides is described in this account. The incorporation of this functional group has evolved from more simplistic approaches to more complex or unusual methods. Past and current synthetic strategies to incorporate the terminal imide functionality are explained with particular emphasis on low‐coordinate titanium environments bearing this ubiquitous but vital type of motif. More recently, the imide functionality has demonstrated to be a key intermediate for modeling important industrial processes such as the hydrodenitrogenation of crude oil.
Hochdurchsatz‐Methoden in der Festkörperchemie. Schneller zum Ziel
Authors: Bauer Sebastian , Stock Norbert
Published: September 2007

Hochdurchsatz‐Methoden zeichnen sich gegenüber konventionellen Methoden durch eine größere Effizienz aus. Mittlerweile steht im Bereich der Anorganischen Festkörperchemie und der Materialwissenschaften eine Vielzahl von Werkzeugen zur Verfügung, um die Entdeckung und Optimierung von Materialien durch Verwendung von HD‐Methoden schneller voranzutreiben. Für alle Arbeitstechniken gilt: Das Ausmaß der Automatisierung, Parallelisierung und Miniaturisierung sowie die Integration aller Einzelschritte in einen Gesamtprozess bestimmt die Effizienz einer HD‐Methodik. Durch eine systematische Untersuchung des Parameterraumes und durch sorgfältige Datenevaluierung (möglichst Software‐gestützt) können Trends gefunden werden, die zu einem besseren Verständnis der untersuchten Systeme beitragen.

Der vorgestellte Ansatz zur HD‐Untersuchung von Solvothermalreaktionen erlaubt die automatisierte Synthese und Charakterisierung von bis zu 48 Produkten ohne die Proben einzeln manipulieren zu müssen. Der geringe Reagenzienverbrauch zusammen mit der Möglichkeit, die Reaktionen unter identischen Prozessparametern (Temperatur, Zeit, Druck, usw.) durchführen zu können, ermöglichen die systematische Untersuchung eines größeren Parameterraumes. An Hand zahlreicher Beispiele haben wir das Potential von Hochdurchsatz‐ Methoden bei der Entdeckung neuer Verbindungen, der Optimierung von Reaktionen, beim Auffinden von Reaktionstrends sowie der Untersuchung des Einflusses von Prozessparametern gezeigt.
Die Träume von den Schäumen. Detergenzien und Tenside
Authors: Schulze‐Schlarmann Judith , Stubenrauch Cosima
Published: September 2007

Schäume kommen in vielen verschiedenen Bereichen in Industrie und Haushalt zur Anwendung, so etwa bei Spülmitteln, Shampoos oder bei der Herstellung von Schaumstoffen. Noch ist aber in den meisten Fällen nicht geklärt, unter welchen Bedingungen Schäume stabil sind oder in sich zusammenfallen. Daher ist es von großem Interesse, die Eigenschaften von Schäumen vorhersagen zu können, wodurch zeit‐ und kostenaufwändige Versuche im “Trial‐and‐error”‐Verfahren vermieden werden könnten. Zu diesem Zweck müssen aber nicht nur die Schäume an sich, sondern auch die Schaumfilme untersucht werden, aus denen der Schaum aufgebaut ist. Einen Einfluss auf die Stabilität haben mit Sicherheit die verwendeten Tenside, deren Konzentration, aber auch Additive wie Parfümöle oder Alkohole. In diesem Beitrag werden Untersuchungen zur Schaum‐ und Schaumfilmstabilität vorgestellt und erste Zusammenhänge erläutert. Allerdings wird auch deutlich, dass es noch viele Fragen gibt, die bisher nicht geklärt werden konnten.
Parabolic recovery of boundary gradients
Authors: Löhner Rainald , Cebral Juan , Appanaboyina Sunil
Published: September 2007

A parabolic recovery procedure suited for shear stress and heat flux recovery on surfaces from linear element data is proposed. The information required consists of the usual unknowns at points, as well as gradients recovered at the points that are one layer away from the wall. The procedure has been in use for some time and has consistently delivered superior results as compared with the usual wall shear stress and heat flux obtained from linear finite element method shape functions. Copyright © 2007 John Wiley & Sons, Ltd.
A Straightforward Synthesis of Enantiopure Bicyclic Azetidines
Authors: Sivaprakasam Mangaleswaran , Couty François , David Olivier , Marrot Jérôme , Sridhar Regati , Srinivas Boga , Rama Rao Kakulapati
Published: September 2007

Enantiomerically pure 1‐azabicyclo[3.2.0]heptane derivatives were synthesized in a straightforward manner from readily available chiral sources, namely, enantiomerically pure epoxides and L‐proline. The key step of this synthesis relied on a diastereoselective intramolecular alkylation of a proline enolate, which led to an azetidine ring fused to a five‐membered ring. These strained bicyclic nitrogen derivatives were found to be good precursors for the preparation of azepanes, after transformation into the corresponding ammonium trifluoromethanesulfonates followed by reaction with nucleophiles.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Chitosan/polyethylene glycol blend fibers and their properties for drug controlled release
Authors: Wang Qun , Zhang Na , Hu Xianwen , Yang Jianhong , Du Yumin
Published: September 2007

Fibers of chitosan and polyethylene glycol (PEG), with salicylic acid as model drug incorporated in different concentrations, were obtained by spinning their solution through a viscose‐type spinneret into a coagulating bath containing aqueous tripolyphosphate and ethanol. Chemical, morphological, and mechanical properties characterization were carried out, as well as the studies of the factors that influence the drug releasing from chitosan/PEG fibers. These factors included the component ratio of chitosan and PEG, the loaded amount of salicylic acid, the pH and the ionic strength of the release solution and others. The diameter of the fibers is around 15 ± 3 μm. The best values of the tensile strength at 12.86 cN/tex and breaking elongation at 21.13% of blend fibers were obtained when the PEG content was 8 and 5 wt %, respectively; the water‐retention value of blend fibers increased as the composition of PEG was raised. The results of controlled release tests showed that the amount of salicylic acid released increased with an increase in the proportion of PEG present in the fiber. Moreover, the release rate of drug decreased as the amount of drug loaded in the fiber increased, but the cumulative release amount is increasing. The chitosan/PEG fibers were also sensitive to pH and ionic strength. The release rate was being accelerated by a lower pH and a higher ionic strength, respectively. All the results indicated that the chitosan/PEG fiber was potentially useful in drug delivery systems. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Delivery of rapamycin‐loaded nanoparticle down regulates ICAM‐1 expression and maintains an immunosuppressive profile in human CD34+ progenitor‐derived dendritic cells
Authors: Das Saswati , Haddadi Azita , Veniamin Simona , Samuel John
Published: September 2007

Immune responses of dendritic cells (DCs) can be modulated by delivery of adjuvants to alter their maturation profile. The purpose of this study was to generate DCs from CD34+ cells of human cord blood and characterize the effects of poly(D,L‐lactic‐co‐glycolic acid) (PLGA)‐nanoparticle encapsulated rapamycin in generating an immunosuppressive DC. Expression of ICAM‐1 (intercellular adhesion molecule), a key molecule in DC‐T cell interaction was increased in mature DCs in response to lipopolysaccharide (LPS). When rapamycin was encapsulated in the nanoparticle to maintain DCs in the immature state, ICAM‐1 expression was down regulated. When delivered in the free form, rapamycin did not alter the expression of ICAM‐1. Cytokine arrays exhibited an immunosuppressive profile of various cytokines in response to the nanoparticulate delivery of rapamycin. In addition, RT‐PCR data demonstrated the presence of toll like receptor (TLR) 9 transcripts, although our DCs are myeloid in nature. In summary, our study demonstrates that DCs may be rendered immunosuppressive upon delivery of rapamycin‐containing nanoparticles. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Chemical and topographical modification of PHBV surface to promote osteoblast alignment and confinement
Authors: Kenar H. , Kocabas A. , Aydinli A. , Hasirci V.
Published: September 2007

Proper cell attachment and distribution, and thus stronger association in vivo between a bone implant and native tissue will improve the success of the implant. In this study, the aim was to achieve promotion of attachment and uniform distribution of rat mesenchymal stem cell‐derived osteoblasts by introducing chemical and topographical cues on poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) film surfaces. As the chemical cues, either alkaline phosphatase was covalently immobilized on the film surface to induce deposition of calcium phosphate minerals or fibrinogen was adsorbed to improve cell adhesion. Microgrooves and micropits were introduced on the film surface by negative replication of micropatterned Si wafers. Both chemical cues improved cell attachment and even distribution on the PHBV films, but Fb was more effective especially when combined with the micropatterns. Cell alignment (<10° deviation angle) parallel to chemically modified microgrooves (1, 3, or 8 μm groove width) and on 10 μm‐thick Fb lines printed on the unpatterned films was achieved. The cells on unpatterned and 5 μm‐deep micropitted films were distributed and oriented randomly. Results of this study proved that microtopographies on PHBV can improve osseointegration when combined with chemical cues, and that microgrooves and cell adhesive protein lines on PHBV can guide selective osteoblast adhesion and alignment. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Skeletal metastases: Decreasing tumor burden by targeting the bone microenvironment
Authors: Chirgwin John M. , Guise Theresa A.
Published: September 2007

Several common cancers often metastasize to the skeleton in advanced disease. Bone metastases are incurable and cause protracted, severe symptoms. Growth of tumor in bone is driven by a vicious cycle: tumor‐secreted factors stimulate bone cells, which in turn release growth factors and cytokines. The bone‐derived factors fuel the vicious cycle by acting back on the tumor cells. The vicious cycle offers novel targets for the treatment of advanced cancers. Treatments can inhibit bone cells (osteoclasts and osteoblasts) that are stimulated by tumor‐secreted factors. Drugs can also inhibit tumor responses to factors enriched in the bone microenvironment, such as transforming growth factor‐β. Animal models show that these approaches, especially combination treatments, can reduce tumor burden. The results suggest a novel paradigm in which tumor growth can be effectively inhibited by drugs that target cells in the bone microenvironment and not the tumor cells themselves. J. Cell. Biochem. 102: 1333–1342, 2007. © 2007 Wiley‐Liss, Inc.
RNA interference‐mediated silencing of the PAR gene inhibits the growth of PC3 cells via the induction of G2/M cell cycle arrest and apoptosis
Authors: Xu Xiao‐Feng , Zhang Zheng‐Yu , Ge Jing‐Ping , Cheng Wen , Zhou Si‐Wei , Zhang Xu , Xu Qi , Wei Zhi‐Feng , Gao Jian‐Ping
Published: September 2007

Background

The prostate androgen‐regulated (PAR) gene is ubiquitously overexpressed in prostate cancer (PCa) cells and is involved in proliferation of PCa. However, the mechanism by which the modulation of PAR gene expression elicits its biological effects on PCa cells is not well documented. Here, we investigate the mechanism of PAR depletion inhibiting PCa cell growth.

Methods

PAR expression was depleted by small interfering RNA (siRNA) and its subsequent effects on proliferation of PC3 cells were determined by the trypan blue exclusion assay. Flow cytometric analysis provided the evidence for the progression of cell cycle and the induction of apoptosis which was further confirmed by the observation of cleavage of poly(ADP‐ribose) polymerase. Western blot analysis was performed to investigate the involvement of critical molecular events known to regulate the cell cycle and the apoptotic machinery.

Results

siRNA transfection results in a dose‐dependent inhibition of cell growth in PC3 cells by causing G2/M phase cell cycle arrest and apoptosis. The G2/M arrest by PAR depletion was associated with decreased levels of cyclin B1, pCdc2 (Tyr15), Cdc2 and Cdc25C. PAR depletion also was found to result in inhibition of procaspases 9, 8, 6 and 3 with significant increase in the ratio of Bax : Bcl‐2.

Conclusions

Our data indicate that PAR depletion induces G2/M arrest via the Cdc25C‐Cdc2/cyclin B1 pathway. Furthermore, the results of the present study point toward involvement of pathways mediated by both caspase 8 and caspase 9 in apoptosis induction by PAR depletion. Copyright © 2007 John Wiley & Sons, Ltd.
Unconventional Methyl Galactan Synthesized via the Thexyldimethylsilyl Intermediate: Preparation, Characterization, and Properties
Authors: Koschella Andreas , Inngjerdingen Kari , Paulsen Berit S. , Morris Gordon A. , Harding Stephen E. , Heinze Thomas
Published: September 2007

Reaction of a β‐(1 → 4) linked galactan with TDMS chloride followed by methylation and desilylation yields methyl galactans with unconventional functionalization patterns. The products were characterized via FTIR and NMR of the intact polymer and by CE after controlled depolymerization. A TDMS‐derivatized methyl galactan contains differently methylated secondary hydroxyl groups. SEC and analytical ultracentrifugation showed a consistent decrease in the molecular weight after the consecutive reaction steps. Biological studies revealed that the methyl galactans are less active in complement fixation assays as compared with a 3‐O‐methyl galactan‐enriched polysaccharide fraction isolated from Acanthus ebracteatus.

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Proton Conducting Membranes Obtained by Doping Radiation‐Grafted Basic Membrane Matrices with Phosphoric Acid
Authors: Schmidt Christian , Schmidt‐Naake Gudrun
Published: September 2007

By grafting 4‐vinylpyridine (4VP), N‐vinylformamide (NVF), and 1‐vinylimidazole (1VIm) onto electron beam irradiated ETFE and FEP films, the basic membrane matrices ETFE‐graft‐poly(4VP), FEP‐graft‐poly(4VP), ETFE‐graft‐poly(1VIm), and ETFE‐graft‐poly(vinylamine), after subsequent hydrolysis of ETFE‐graft‐poly(NVF), can be obtained. These matrices are doped with phosphoric acid to produce acid–base composite materials that exhibit high proton conductivities up to 100 mS · cm−1 at high temperatures (120 °C) and no humidification. The produced membranes are robust, flexible, and mechanically stable even at high doping levels and endure temperatures of up to 160 °C. Preliminary tests in H2/O2 fuel cells provide power densities between 75 and 150 mA · cm−2 at 120 °C without humidification.

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Molecularly Imprinted Multi‐Layer Core‐Shell Nanoparticles – A Surface Grafting Approach
Authors: Pérez‐Moral Natalia , Mayes Andrew G.
Published: September 2007

Surface initiated living‐radical polymerization (SIP) based on dithiocarbamate iniferters has been used to create molecularly imprinted core‐shell (CS) nanoparticles. Using this approach, propranolol, morphine and naproxen have been successfully imprinted in particle shells (the latter could not be imprinted using conventional aqueous‐based CS methods). Rebinding properties of the imprinted particles appear to be similar to those made by alternative methods. The living radical initiation mechanism makes it possible to build complex multi‐layer particles sequentially. As a demonstration, multi‐layer propranolol‐imprinted particles were generated. Two additional functional shells were grown over the imprinted shell, while the propranolol binding was retained, albeit at a reduced level.

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Convergence and stabilization of stress‐point integration in mesh‐free and particle methods
Authors: Fries Thomas‐Peter , Belytschko Ted
Published: September 2007

Stress‐point integration provides significant reductions in the computational effort of mesh‐free Galerkin methods by using fewer integration points, and thus facilitates the use of mesh‐free methods in applications where full integration would be prohibitively expensive. The influence of stress‐point integration on the convergence and stability properties of mesh‐free methods is studied. It is shown by numerical examples that for regular nodal arrangements, good rates of convergence can be achieved. For non‐uniform nodal arrangements, stress‐point integration is associated with a mild instability which is manifested by small oscillations. Addition of stabilization improves the rates of convergence significantly. The stability properties are investigated by an eigenvalue study of the Laplace operator. It is found that the eigenvalues of the stress‐point quadrature models are between those of full integration and nodal integration. Stabilized stress‐point
integration is proposed in order to improve convergence and stability properties. Copyright © 2007 John Wiley & Sons, Ltd.
Influence of different process and material parameters on chemical foaming of fluorinated ethylene propylene copolymers
Authors: Zirkel Larissa , Münstedt Helmut
Published: September 2007

In this article, the chemical foaming of fluorinated ethylene propylene copolymers (FEP) is investigated. For the laboratory scale foam extrusion process, a chemical blowing agent adapted to the high melting temperature of FEP had to be found. Foaming experiments were carried out varying process and material parameters. Foam densities as well as cellular structures were analyzed to characterize how the parameters influence the foaming behavior of the FEP melt. An increasing rate of the foam extrusion caused an augmentation of cell numbers at a simultaneous decrease of their diameters. Moreover, a pronounced reduction of the foam density with increasing output rate could be observed. Changing the temperature of the foam extrusion, an optimum in density reduction and homogeneity of the cell size was found. Furthermore, the influence of an appropriate nucleation agent on the resulting geometry and amount of cells was investigated. Though the chemical blowing agent itself can act as an implement for nucleating cell growth, an addition of 10 wt% of calcium fluoride particles showed a significant augmentation in cell quantity. For the chemical foam extrusion process, three FEP with different viscosities were characterized. With decreasing viscosity, a reduction in foam density could be observed for all temperatures. POLYM. ENG. SCI., 47:1740–1749, 2007. © 2007 Society of Plastics Engineers
Eco‐plastics: Morphological and mechanical properties of recycled poly(carbonate)‐crushed rubber (rPC‐CR) blends
Authors: Zribi K. , Elleuch K. , Feller J.F. , Bourmaud A. , Elleuch B.
Published: September 2007

Crushed tire rubber particles (CR) have been dispersed into a recycled poly(carbonate) matrix (rPC) to obtain an eco‐friendly plastic (EFP). A positive synergy was expected from the association of an elastomeric phase to a tough thermoplastic matrix, helping on the other hand to develop a plastic with low impact on the environment. Mechanical melt‐mixing alone cannot provide a suitable interface, and led to blends with poor mechanical properties. Consequently, we have investigated different strategies to improve the EFP properties: First, the rubber surface has been treated by flaming or washing with dichloromethane and second, two copolymers, poly(ethylene‐co‐ethyl acrylate‐tert‐hydroxyl methacrylate) (E‐EA‐MAH) and poly(ethylene‐co‐methyl acrylate‐ter‐glycidyl methacrylate) (E‐MA‐GMA), were used to compatibilize CR particles with rPC matrix by reactive melt‐mixing in an internal mixer. The resulting blends mechanical properties were studied through static tension experiments and interpreted to the light of electronic microscopy fractography analysis and nanoindentation experiments. Significant gain of mechanical properties can be obtained by decreasing CR size under 140 μm (especially for CR contents between 5 and 20% m/m). To reach similar properties with rubber particles of diameter over 140 μm (but under 350 μm), it is necessary to activate their surface by either dichloromethane washing or flaming. Additional use of a compatibilizer extends the plastic behaviour domain of the EFP. rPC‐20% w/w CR is the best alternative material of our study. POLYM. ENG. SCI., 47:1768–1776, 2007. © 2007 Society of Plastics Engineers
Crosslinking of rotational molding foams of polyethylene
Authors: Marcilla A. , García‐Quesada J.C. , Ruiz‐Femenia R. , Beltrán M.I.
Published: September 2007

Rotational molding of foamed polyethylene has increasingly become an important process in industry due to its ability to produce innovative and high added value parts with little specialist equipment required. The polyolefin foam production tends to achieve the highest possible cell size uniformity and cell size reduction. To improve the cell morphology of the PE foams, the cell coalescence and coarsening might be suppressed, which can be accomplished preserving the melt strength of the polymer during processing. With this aim, in this work two peroxides have been used to enhance the melt strength of a linear low‐density polyethylene by chemical crosslinking. The moldings have been processed at different oven residence times and they have been characterized according to their density, gel content, bubble size distribution and impact strength. Despite the lower crosslinking degree attained by the crosslinked foams, the results show an enhancement in the cell morphology of these moldings, which are able to keep their cell size distribution even with the longest processing times and consequently the processing window of these rotational molding foams is widened. POLYM. ENG. SCI., 47:1804–1812, 2007. © 2007 Society of Plastics Engineers
Effect of melt processing conditions on the morphology and properties of nylon 6 nanocomposites
Authors: Chavarria F. , Shah R.K. , Hunter D.L. , Paul D.R.
Published: September 2007

Nylon 6 (PA‐6) organoclay nanocomposites were prepared by melt processing using three different twin screw extruders (TSEs). The effect of mixing conditions, feed port location, residence time, and number of extrusion passes on the morphology and mechanical properties of the nanocomposites were examined. Wide‐angle X‐ray scattering, transmission electron microscopy (TEM), and mechanical property data are reported. Particle analyses were performed on the TEM images to quantitatively characterize the extent of exfoliation. The amount of shear and the mixing conditions created by TSEs have a significant effect on the morphology and properties of PA‐6 nanocomposites. Morphology and mechanical property results show that (1) melting the polymer before coming into contact with the organoclay followed by a low level of shear and (2) maintaining a medium level of shear throughout the extruder with a longer residence time lead to extremely high platelet dispersion and matrix reinforcement for PA‐6 nanocomposites. Nanocomposites formed in a DSM microcompounder showed similar morphologies and modulus trends as those obtained with conventional TSEs; thus, this microcompounder is a good alternative for nanocomposite research especially when only small amounts of material are available. POLYM. ENG. SCI., 47:1847–1864, 2007. © 2007 Society of Plastics Engineers
Comparison of vertical and horizontal slot die coatings
Authors: Chang Hsien‐Ming , Chang Yu‐Rong , Lin Chi‐Feng , Liu Ta‐Jo
Published: September 2007

Comparison of vertical and horizontal slot coatings was carried out experimentally using aqueous glycerin solutions with varying viscosity on a laboratory‐scale slot coater. The maximum coating speeds achieved in vertical slot coating were found to be higher than those of horizontal slot coating for low‐viscosity solutions. The coating defects observed below the minimum wet thickness changed from ribbing to air entrainment at a critical solution viscosity of around μ = 75 mPa s. Above this critical viscosity, a lower minimum wet thickness was obtained for the horizontal coating but not for vertical coating. The difference between vertical and horizontal coating was mainly the length of the coating bead. The dimensionless minimum wet thickness was correlated as a function of Reynolds number. There existed three regions of minimum wet thickness depending on Reynolds number. Initially, the dimensionless wet thickness increased in the low Reynolds number region (Region I), then reached a plateau in the intermediate Re region (Region II), finally dropped off sharply in the high Re region (Region III). The boundaries of these three regions were identified by two critical Reynolds numbers, i.e., Re = 1 and 20. Only Regions I and II of the wet thickness could be found for horizontal coating, while mainly Regions II and III were obtained for vertical coating, depending on the viscosity of the coating solution. POLYM. ENG. SCI., 47:1927–1936, 2007. © 2007 Society of Plastics Engineers
Analysis of gene expression in two human‐derived cell lines exposed in vitro to a 1.9 GHz pulse‐modulated radiofrequency field
Authors: Chauhan Vinita , Qutob Sami S. , Lui Stephanie , Mariampillai Anu , Bellier Pascale V. , Yauk Carole L. , Douglas George R. , Williams Andrew , McNamee James P.
Published: September 2007

There is considerable controversy surrounding the biological effects of radiofrequency (RF) fields, as emitted by mobile phones. Previous work from our laboratory has shown no effect related to the exposure of 1.9 GHz pulse‐modulated RF fields on the expression of 22 000 genes in a human glioblastoma‐derived cell‐line (U87MG) at 6 h following a 4 h RF field exposure period. As a follow‐up to this study, we have now examined the effect of RF field exposure on the possible expression of late onset genes in U87MG cells after a 24 h RF exposure period. In addition, a human monocyte‐derived cell‐line (Mono‐Mac‐6, MM6) was exposed to intermittent (5 min ON, 10 min OFF) RF fields for 6 h and then gene expression was assessed immediately after exposure and at 18 h postexposure. Both cell lines were exposed to 1.9 GHz pulse‐modulated RF fields for 6 or 24 h at specific absorption rates (SARs) of 0.1–10.0 W/kg. In support of our previous results, we found no evidence that nonthermal RF field exposure could alter gene expression in either cultured U87MG or MM6 cells, relative to nonirradiated control groups. However, exposure of both cell‐lines to heat‐shock conditions (43°C for 1 h) caused an alteration in the expression of a number of well‐characterized heat‐shock proteins.
Raman spectroelectrochemistry on SWNTs at higher doping levels: Evidence for a transition to intercalative doping
Authors: Rafailov P. M. , Thomsen C. , Dettlaf‐Weglikowska U. , Hornbostel B. , Roth S.
Published: September 2007

We studied the transition from the electrochemical double‐layer charging regime to intercalative doping of SWNT buckypaper in KCl aqueous solution. For this purpose we used doping levels by applying constant potentials above 1 V approaching and slightly exceeding the oxidation potential for Cl– ions. At each potential in situ Raman measurements of the radial breathing mode (RBM), the high‐energy tangential mode (HEM) and the disorder‐induced (D) mode were performed. From a comparative analysis of the Raman spectra we conclude that above 1 V a significant penetration of chlorine species into the interstitial channels of the SWNT bundles and possibly functionalization take place. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth mechanism of solution‐deposited layers of the charge‐transfer salt CuDDQ
Authors: Weitz Ralf Thomas , Rauschenbach Stephan , Forment‐Aliaga Alicia , Burghard Marko , Kern Klaus
Published: September 2007

Charge‐transfer (CT) salts such as copper‐2,3‐dichloro‐5,6‐dicyano‐p ‐benzoquinone (CuDDQ) are promising components of reversible resistive memory switching devices. In the study presented here, we report on the composition of CuDDQ layers grown from acetonitrile containing solution onto copper‐coated silicon substrates. According to Rutherford Backscattering Spectrometry (RBS) experiments, the CuDDQ film is homogeneously composed of copper and DDQ across its whole thickness, and the ratio between copper and DDQ is 1:1. A complex between copper and acetonitrile has been identified by Electro Spray Ionization (ESI) time‐of‐flight mass spectrometry as the main source of copper ions for the CuDDQ layer formation. In contrast, if ethanol is used as solvent, no copper‐ethanol complex can be discerned from the ESI mass spectrum. This finding underlines the vital role of acetonitrile as the main copper source for the complexation reaction with DDQ. The continuous availability of the copper‐acetonitrile complex in solution during the growth of the CuDDQ layers explains their homogeneity as determined by RBS. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of polymer films with embedded single‐wall carbon nanotubes
Authors: Chernov A. I. , Obraztsova E. D. , Lobach A. S.
Published: September 2007

In this work the thin polymer films (based on polyvinyl alcohol or carboxymetylcellulose) containing single‐wall carbon nanotubes synthesized by different methods have been fabricated by a novel technology and studied in detail by UV–VIS–NIR optical absorption and Raman scattering techniques. The films are prospective as an optical material with a high non‐linearity. This property allows using them as ultra‐fast saturable absorbers in different laser schemes, especially, in fiber lasers. The optical spectroscopy has been used for optimization of several film parameters: an optical density, a thickness, a level of scattered light and proximity of the film absorption bands to the operation wavelengths of different solid state lasers. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An evaluation of the growth of nitrides on semipolar substrates using two indicators
Authors: Gil Bernard , Bigenwald Pierre , Briot Olivier
Published: September 2007

We evaluate the properties of nitride heterostructures on semipolar substrates using two indicators: the cancellation of the Quantum Confined Stark Effect and the volume density of elastic energy stored in the strained layers of GaN–GaInN heterostructures lattice‐matched to (hkl)‐oriented GaN semipolar substrates. These two parameters indicate that the growth on specific orientations is a plus when compared to growth on (0001) polar substrates. We will show that, unfortunately, one cannot simultaneously minimize the stored elastic energy and cancel the Quantum Confined Stark Effect, but it is possible to significantly reduce both of them. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tandem mass spectrometry acquisition approaches to enhance identification of protein‐protein interactions using low‐energy collision‐induced dissociative chemical crosslinking reagents
Authors: Soderblom Erik J. , Bobay Benjamin G. , Cavanagh John , Goshe Michael B.
Published: September 2007

Chemical crosslinking combined with mass spectrometry is a useful tool for studying the topological organization of multiprotein interactions, but it is technically challenging to identify peptides involved in a crosslink using tandem mass spectrometry (MS/MS) due to the presence of product ions originating from both peptides within the same crosslink. We have previously developed a novel set of collision‐induced dissociative chemical crosslinking reagents (CID‐CXL reagents) that incorporate a labile bond within the linker which readily dissociates at a single site under low‐energy collision‐induced dissociation (CID) to enable independent isolation and sequencing of the crosslinked peptides by traditional MS/MS and database searching. Alternative low‐energy CID events were developed within the in‐source region by increasing the multipole DC offset voltage (ISCID) or within the ion trap by increasing the collisional excitation (ITCID). Both dissociation events, each having their unique advantages, occur without significant backbone fragmentation to the peptides, thus permitting subsequent CID to be applied to these distinct peptide ions for generation of suitable product ion spectra for database searching. Each approach was developed and applied to a chemical crosslinking study involving the N‐terminal DNA‐binding domain of AbrB (AbrBN), a transition‐state regulator in Bacillus subtilis. A total of thirteen unique crosslinks were identified using the ITCID approach which represented a significant improvement over the eight unique crosslinks identified using the ISCID approach. The ability to segregate intrapeptide and interpeptide crosslinks using ITCID represents the first step towards high‐throughput analysis of protein‐protein crosslinks using our CID‐CXL reagents. Copyright © 2007 John Wiley & Sons, Ltd.
Influence of a 4‐aminomethylbenzoic acid residue on competitive fragmentation pathways during collision‐induced dissociation of metal‐cationized peptides
Authors: Osburn Sandra , Ochola Sila , Talaty Erach , Van Stipdonk Michael
Published: September 2007

Formation of [bn + 17 + cat]+ is a prominent collision‐induced dissociation (CID) pathway for Li+‐ and Na+‐cationized peptides. Dissociation of protonated and Ag+‐cationized peptides instead favors formation of the rival b/[bn−1 + cat]+ species. In this study the influence of a 4‐aminomethylbenzoic acid (4AMBz) residue on the relative intensities of [b3−1 + cat]+ and [b3 + 17 + cat]+ fragment ions was investigated using several model tetrapeptides including those with the general formula A(4AMBz)AX and A(4AMBz)GX (where X = G, A, V). For Li+‐ and Na+‐cationized versions of the peptides there was a significant increase in the intensity of [b3−1 + cat]+ for the peptides that contain the 4AMBz residue, and in some cases the complete elimination of the [b3 + 17 + cat]+ pathway. The influence of the 4AMBz residue may be attributed to the fact that [b3−1 + cat]+ would be a highly conjugated species containing an aromatic ring substituent. Comparison of CID profiles generated from Na+‐cationized AAGV and A(4AMBz)GV suggests an apparent decrease in the critical energy for generation of [b3−1 + Na]+ relative to that of [b3 + 17 + Na]+ when the aromatic amino acid occupies a position such that it leads to the formation of the highly conjugated oxazolinone, thus leading to an increase in formation rate for the former compared to the latter. Copyright © 2007 John Wiley & Sons, Ltd.
Efficient enrichment and desalting of protein digests using magnetic mesocellular carbon foams in matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Kim Young‐Pil , Cho Kun , Lee Dohoon , Piao Yunxian , Ahn Yeong Hee , Yoo Jong Shin , Hyun Taeghwan , Kim Hak‐Sung
Published: September 2007

We demonstrate that magnetic mesocellular carbon foams (Mag‐MCF‐C) can be effectively used for enrichment and desalting of protein digests or peptides in matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS). The large mesocellular pores and surface area of Mag‐MCF‐C are likely to mainly contribute to high efficiency in enrichment and desalting of protein digests. The magnetic property of Mag‐MCF‐C enabled easy and simple enrichment and desalting process comprising adsorption, washing, and separation steps by using an external magnet. Following elution from Mag‐MCF‐C by using a matrix solution (CHCA in 70% ACN/0.1% TFA), the peptides were subjected to MALDI‐MS analysis. As a result, MALDI mass spectra of peptides or tryptic protein digests were distinct even at a peptide concentration as low as 50 pM. The use of Mag‐MCF‐C resulted in significantly improved sequence coverage for protein identification when compared to other conventional methods. Mag‐MCF‐C will find applications in mass spectrometric analysis of low abundance peptides or protein digests with high sensitivity. Copyright © 2007 John Wiley & Sons, Ltd.
The Ecology of Adolescent Substance Abuse Service Utilization
Authors: Jones Diana L. , Heflinger Craig Anne , Saunders Robert C.
Published: September 2007

This paper presents an ecological‐community model toward the explanation of variation in patterns of substance abuse (SA) service utilization among adolescents who are enrolled in Tennesssee's Medicaid program (TennCare). Guided by a theoretical framework that draws from the social ecology work of Bronfenbrenner and health services utilization models promoted by Aday and Andersen, we apply a social indicators approach toward explaining the impact of community ecology on identification of SA and treatment engagement. Both county‐level rates and individual‐level treatment utilization are examined and hierarchical linear modeling is incorporated to examine the individual‐in‐community phenomenon. This study is an expansion of previous service utilization research and suggests that explanations of youth's service utilization must necessarily include not only individual, familial, and service system characteristics, but community factors, as well.
SVH‐B interacts directly with p53 and suppresses the transcriptional activity of p53
Authors: Zhou Xinyuan , Yang Guohua , Huang Ruimin , Chen Xiaotao , Hu Gengxi
Published: September 2007

We previously reported that inhibition of SVH‐B, a specific splicing variant of SVH, results in apoptotic cell death. In this study, we reveal that this apoptosis may be dependent on the presence of p53. Co‐immunoprecipitation and GST pull‐down assays have demonstrated that SVH‐B directly interacts with p53. In both BEL‐7404 cells and p53‐null Saos‐2 cells transfected with a temperature‐sensitive mutant of p53, V143A, ectopically expressed SVH‐B suppresses the transcriptional activity of p53, and suppression of SVH by RNA interference increases the transcriptional activity of p53. Our results suggested the function of SVH‐B in accelerating growth and inhibition of apoptosis is related to its inhibitory binding to p53.