bluuebunny/crossref_metadata_2025 huggingface dataset:
Maßgenaues Mauerwerk für den hochwertigen Rohbau
Authors: Schwieger Hartmut
Published: April 2007

Im Laufe der Zeit haben sich die Anforderungen an Baustoffe und Bauteile gewandelt. Bereits an den Rohbau werden heute hohe Anforderungen gestellt, die noch vor Jahrzehnten undenkbar waren. An die Stelle von Improvisationskunst ist die durchorganisierte Baustellenlogistik getreten, die zu hoher Wirtschaftlichkeit bei gleichzeitig hoher Qualität führt.

Insbesondere Immobilienmakler und Bauträger wissen, welche Wirkung ein ordentlicher Rohbau und eine saubere Baustelle auf potenzielle Käufer und Nutzer haben. Die Erstbesichtigung während der Rohbauphase ist dabei ein entscheidendes Mittel der Vertrauensbildung. Eine aufgeräumte Baustelle, bei der offensichtlich die Bauunternehmer ihr Handwerk verstehen, bestärken Käufer und Nutzer in der Entscheidung für Bauwerk, Baustoff und Bauausführende. Im Gegensatz dazu hat eine unsaubere Baustelle mit schlampiger Verarbeitung zur Folge, dass die Käufer und zukünftigen Nutzer ihre Entscheidung in Frage stellen, weil Zweifel an der Qualität der Ausführung aufkommen. Der Zustand des Rohbaus kann daher die Entscheidung des Erwerbers/Nutzers maßgeblich beeinflussen und/oder bestätigen.
Semidiscrete formulations for transient transport at small time steps
Authors: Harari Isaac , Hauke Guillermo
Published: April 2007

Solutions of direct time‐integration schemes for transient advection–diffusion–reaction problems that converge in time to conventional semidiscrete formulations may be polluted at small time steps by spurious spatial oscillations. This degradation is not an artifact of the time‐marching scheme, but rather a property of the solution of the semidiscrete Galerkin approximation itself. An analogy to steady advection–diffusion–reaction problems with a modified reaction coefficient by the Rothe method of discretizing in time prior to spatial discretization provides an upper bound on the time step for the onset of spatial instability. Spatial stabilization removes this pathology, leading to stabilized implicit time‐integration schemes that are free of spurious oscillations at small time steps. Copyright © 2007 John Wiley & Sons, Ltd.
A simple axisymmetric extension to virtual cell embedding
Authors: Tang J.
Published: April 2007

Virtual cell embedding (VCE) is a simple cartesian gridding method that subdivides cells into discrete subcells to obtain the approximate obstructed cell area and side lengths. It can be used to make a very fast calculation method for the Euler equations in two dimensions. However, the original procedure for two spatial dimensions is inadequate for axisymmetric geometries, where radial co‐ordinates of cells and interfaces need to be known. Presented in this paper is a short, simple extension of the VCE method to handle axisymmetric cases with an accuracy consistent with the basic VCE surface representation in planar geometries. The method will be tested in basic conical flow simulations to show its usefulness for practical engineering design purposes. Copyright © 2007 John Wiley & Sons, Ltd.
Epigenetic silencing of the candidate tumor suppressor gene PROX1 in sporadic breast cancer
Authors: Versmold Beatrix , Felsberg Jörg , Mikeska Thomas , Ehrentraut Denise , Köhler Juliane , Hampl Juergen A. , Röhn Gabriele , Niederacher Dieter , Betz Beate , Hellmich Martin , Pietsch Torsten , Schmutzler Rita K. , Waha Andreas
Published: April 2007

Extensive hypermethylation and consecutive transcriptional silencing of tumorsuppressor genes have been documented in multiple tumor entities including breast cancer. In a microarray based genome‐wide methylation analysis of five sporadic breast carcinomas we identified a hypermethylated CpG island within the first intron of the prospero related homeobox gene 1 (PROX1). We, therefore, investigated CpG island methylation of PROX1 in a series of 33 pairs of primary breast cancer and corresponding normal tissue samples by bisulfite sequencing and COBRA analyses. Seventeen of these (52%) breast cancer samples revealed a significant accumulation of methylated CpG sites along with a significant reduction of PROX1 transcription compared to normal breast tissues of the same patients. Frequent methylation was also observed in brain metastases from primary breast cancer (21/37 = 57% of cases). Secondary, we analysed 38 brain metastases of primary breast carcinomas and detected a significantly reduced expression of PROX1 compared to normal breast tissue (p < 0.001) and primary breast carcinomas (p < 0.05), respectively. Additionally, treatment of breast cancer cell lines with demethylating agents could reactivate PROX1 transcription. In summary, we have identified PROX1 as a novel target gene that is hypermethylated and transcriptionally silenced in primary and metastatic breast cancer. © 2007 Wiley‐Liss, Inc.
Expression of oncofetal RNA‐binding protein CRD‐BP/IMP1 predicts clinical outcome in colon cancer
Authors: Dimitriadis Euthymios , Trangas Theoni , Milatos Stavros , Foukas Periklis G. , Gioulbasanis Ioannis , Courtis Nelly , Nielsen Finn C. , Pandis Nikos , Dafni Urania , Bardi Georgia , Ioannidis Panayotis
Published: April 2007

The oncofetal CRD‐BP/IMP1 RNA binding protein regulates posttranscriptionally a handful of RNA transcripts, implicated in cell adhesion and invadopodia formation and was recently identified as a target of the β‐catenin/Tcf transcription factor that is constitutively activated in colorectal carcinomas (CRCs). The expression of CRD‐BP/IMP1 was studied in normal adult intestines and CRCs. In normal mucosa, CRD‐BP/IMP1 immunoreactivity was observed in few scattered cells located predominantly at or near the bottom of the crypts, whereas in CRCs the protein was detectable in tumor cells of 50% of the specimens analyzed. CRD‐BP/IMP1 mRNA expression was measured by qRT‐PCR in 78 CRCs. Thirty‐two (41%) of the specimens were negative or had negligible expression, whereas the remaining forty‐six (59%) expressed a wide range of CRD‐BP/IMP1 mRNA levels. CRD‐BP/IMP1 mRNA expression correlated with that of the putative stem/progenitor cell marker Musashi‐1 mRNA (p = 0. 035). CRD‐BP/IMP1 positive tumors metastasized and/or recurred more frequently (p = 0.001) and its expression defined a group of patients with shorter survival (p = 0.014). Furthermore, in a multivariate analysis CRD‐BP/IMP1 expression was found to be an independent predictor of survival (p = 0.015). For stage I & II patients, the differences in metastasis/recurrence and survival rates remained significant (p = 0.001 and 0.033, respectively). These findings indicate that CRD‐BP/IMP1 positive tumors exhibit early disease dissemination and unfavorable prognosis. © 2007 Wiley‐Liss, Inc.
Chitosan monomer accelerates alkaline phosphatase activity on human osteoblastic cells under hypofunctional conditions
Authors: Yamada Shizuka , Ganno Tomoko , Ohara Naoko , Hayashi Yoshihiko
Published: April 2007

Chitosan is a natural polyaminosaccharide that is extensively applied as an antitumor and antirheumatic drug. However, there are few reports about its effects on hypofunctional osteoblasts in vitro. We investigated the biological characteristics of a human osteoblastic cell line (NOS‐1 cells) that was cultured with a chitosan monomer‐containing medium under simulated microgravity conditions. After 7 days of cell incubation under the conventional conditions, the flasks were transferred to a microgravity simulator for 3 days. In the 0.005% chitosan monomer supplemented group, the marker enzyme of biological mineralization, the alkaline phosphatase (ALP) activity, was significantly higher compared with the control group (p < 0.05). A cDNA microarray was performed to investigate the effects on the mRNA level by chitosan monomer, and the fluorescent signal was analyzed. The interferon gamma (IFN‐γ) receptor gene was detected with a signal ration of 2.2. The slight increase of IFN‐γ receptor expression was confirmed after 3 days of incubation according to RT‐PCR analysis. Western blot analysis also showed the increased expression of IFN‐γ receptor. These results suggest that a supra‐low concentration of chitosan monomer may increase the ALP activity of osteoblastic cells through the IFN‐γ receptor at the early phase of cell culture and recover the activity for biological mineralization under the hypofunctional condition. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Antibiotic‐containing collagen for the treatment of bone defects
Authors: Rupprecht Stephan , Petrovic Ljubinko , Burchhardt Bettina , Wiltfang Jörg , Neukam Friedrich Wilhelm , Schlegel Karl Andreas
Published: April 2007

Recent studies have explored the use of biodegradable implants that incorporate antibiotics for the treatment of bone infections. In this study, a biodegradable composite containing bovine collagen and teicoplanin (Targobone®) was used for the treatment of mandibular nonunion defects. Patients with mandibular nonunion defects subsequent to osteosynthesis were treated with Targobone® (n = 9) or with autologous bone grafts (n = 12). Clinical and radiological evaluations were performed preoperatively, immediately postoperatively, and 4 and 24 weeks postoperatively. Bone regeneration was defined relative to the original defect area in the panoramic radiograph by using image analysis software. In the Targobone® group, the defect area decreased to 78% (SD ± 21.8%) of the preoperative area within 4 weeks and to 21% (SD ± 9.7%) of the preoperative area within 24 weeks. In the autologous bone graft group, the defect area decreased to 69% (SD ± 32.4%) of the preoperative area within 4 weeks and to 4.7% (SD ± 5.6%) of the preoperative area within 24 weeks. Thus, Targobone® is a promising option for the treatment of bone defects. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Towards a functional radiopaque hydrogel for nucleus pulposus replacement
Authors: Boelen Erik J. H. , Koole Leo H. , van Rhijn Lodewijk W. , van Hooy‐Corstjens Catharina S. J.
Published: April 2007

Patients with severe back pain, attributed to a herniation of the nucleus pulposus of the intervertebral disc, can benefit from a replacement of only the nucleus pulposus, provided the annulus fibrosus is still functional. This study investigated four intrinsically radiopaque hydrogel biomaterials, which were designed specifically to replace the herniated nucleus pulposus. The important characteristic of these hydrogels is that they can be visualized entirely with both MRI and X‐rays. The materials are based on copolymers of N‐vinyl‐2‐pyrrolidinone (NVP) or 2‐hydroxyethyl methacrylate (HEMA) and a radiopacity introducing monomer, 2‐(4′‐iodobenzoyl)‐oxo‐ethyl methacrylate (4IEMA). Two of the formulations also contain the chemical crosslinker allyl methacrylate (AMA). Physical–mechanical properties like the water‐uptake, biocompatibility, stiffness, and fatigue and creep behavior were studied, while keeping an eye on the intended application. All four materials were designed with 5–6 mass % of iodine to ensure sufficient X‐ray visibility between two vertebrae. It was found that the materials display appropriate stiffness and biocompatibility. The crosslinked materials hold most promise as a functional nucleus prosthesis, as they combine these properties also with high water content, fatigue resistance, and recovery after loading. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Comparative in vitro biomechanical evaluation of two soft tissue defect products
Authors: Johnson Wesley , Inamasu Joji , Yantzer Brenda , Papangelou Christopher , Guiot Bernard
Published: April 2007

A soft tissue defect is often an unavoidable consequence of various surgical procedures or a result of trauma. Recently, intraoperative use of xenograft as a patch to the soft tissue defect has become popular with various products available in the market. In this study, mechanical properties of the OrthADAPT™ Bioimplants (Pegasus Biologics, Irvine, CA), new xenograft products composed of collagen from equine pericardium, were evaluated individually and against an existing bioimplant product. The OrthADAPT™ Bioimplants have three subtypes which differ in the degree of crosslinking of collagen strands. The three products are named as FX, PX, and MX in the order of the degree of collagen crosslinking and likely durability in vivo, with FX most dense in crosslinking and hence most durable. The three subtypes underwent three destructive mechanical tests: tensile strength, suture pull‐out strength, and burst strength test. In tensile strength and suture pull‐out strength tests, the three products were compared with CuffPatch™, a similar collagen‐based xenograft product from a competing manufacturer. In the burst strength test, the three products were compared with untreated equine pericardium tissue. In tensile strength and suture pull‐out strength tests, the products FX and MX were shown to have mechanical properties that were comparable with CuffPatch, while the mechanical strength of PX was significantly inferior to FX and CuffPatch in tensile strength test. In burst strength test, there were no differences in mechanical properties among the three OrthADAPT Bioimplants. This study demonstrates the biomechanical equivalence of OrthADAPT with CuffPatch. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Increased tolerance and conversion of inhibitors in lignocellulosic hydrolysates by Saccharomyces cerevisiae
Authors: Almeida João RM , Modig Tobias , Petersson Anneli , Hähn‐Hägerdal Bärbel , Lidén Gunnar , Gorwa‐Grauslund Marie F
Published: April 2007

During hydrolysis of lignocellulosic biomass, monomeric sugars and a broad range of inhibitory compounds are formed and released. These inhibitors, which can be organized around three main groups, furans, weak acids and phenolics, reduce ethanol yield and productivity by affecting the microorganism performance during the fermentation step. Among the microorganisms that have been evaluated for lignocellulosic hydrolysate ethanol fermentation, the yeast Saccharomyces cerevisiae appears to be the least sensitive. In order to overcome the effect of inhibitors, strategies that include improvement of natural tolerance of microorganism and use of fermentation control strategies have been developed. An overview of the origin, effects and mechanisms of action of known inhibitors on S. cerevisiae is given. Fermentation control strategies as well as metabolic, genetic and evolutionary engineering strategies to obtain S. cerevisiae strains with improved tolerance are discussed. Copyright © 2007 Society of Chemical Industry
24S‐hydroxycholesterol in relation to disease manifestations of acute experimental autoimmune encephalomyelitis
Authors: Teunissen C.E. , Floris S. , Sonke M. , Dijkstra C.D. , De Vries H.E. , Lütjohann D.
Published: April 2007

Levels of the brain‐specific cholesterol metabolite 24S‐hydroxycholesterol are proposed as possible biomarkers for multiple sclerosis (MS). It is not yet clear for which aspect of the MS disease manifestations 24S‐hydroxycholesterol is a reflection. We studied the relation of serum levels of 24S‐hydroxycholesterol and other sterols to the disease characteristics of acute experimental autoimmune encephalomyelitis (EAE), an animal model for MS. Serum was analyzed for cholesterol precursors, oxysterols, and plant sterols during the course of disease development. Significantly increased levels of the cholesterol metabolites 24S‐hydroxycholesterol and 27‐hydroxycholesterol were observed on day 9, before the onset of clinical signs. The serum levels of these oxysterols gradually increased up to 193% and 415%, respectively, at day 17, when clinical symptoms had recovered. Total cholesterol levels were slightly but significantly decreased on day 9 and day 17 in treated animals. Serum levels of cholesterol precursors and plant sterols decreased gradually from day 11 and day 14, respectively. Immunostaining of the 24S‐hydroxycholesterol‐forming enzyme Cyp46 was shown in macrophage infiltrates. In vitro experiments confirmed the presence of Cyp46 in macrophages and showed a decreased expression after LPS treatment. The data indicate that changes in serum oxysterols occur early in EAE and can be formed by macrophages. These early changes indicate an important role for oxysterols in the development of EAE. © 2007 Wiley‐Liss, Inc.
Role of c‐Jun N‐terminal kinase in early brain injury after subarachnoid hemorrhage
Authors: Yatsushige Hiroshi , Ostrowski Robert P. , Tsubokawa Tamiji , Colohan Austin , Zhang John H.
Published: April 2007

The c‐Jun N‐terminal kinase (JNK) is induced by cerebral ischemia and injurious blood components acutely after subarachnoid hemorrhage (SAH). We hypothesized that inhibition of JNK will prevent damage to the neurovascular unit in the early brain injury period after SAH. Ninety‐nine male SD rats (300–350 g) were randomly assigned to sham, SAH, and SAH treated with JNK inhibitor groups. SAH was induced by endovascular perforation. The JNK inhibitor SP600125 was administered intraperitoneally at 1 hr before and 6 hr after SAH. At 24 hr after SAH, we observed increased phosphorylation of JNK and c‐Jun. Signs of neurovascular damage were observed in the hemorrhagic brains; these included the increases of aquaporin (AQP)‐1 expression and brain water content as well as enhanced matrix metalloproteinase (MMP)‐9 activity, vascular collagen IV loss, increased VEGF tissue level, and Evans blue extravasation. The appearances of cleaved caspase‐3 expression, TUNEL‐positive cells, and apoptotic morphology in cerebral tissues were associated with neurological deficit after SAH. JNK inhibition prevented c‐Jun phosphorylation and suppressed AQP1, MMP‐9, VEGF, and caspase‐3 activation, with concomitant diminution of neuronal injury, blood–brain barrier preservation, reduced brain swelling, and improved neurological deficit in rats after SAH. This study demonstrates a multitude of beneficial effects of JNK inhibition, including protection of the neurovascular unit in early brain injury after SAH. © 2007 Wiley‐Liss, Inc.
Vancomycin covalently bonded to titanium alloy prevents bacterial colonization
Authors: Antoci Valentin , King Samuel B. , Jose Binoy , Parvizi Javad , Zeiger Allen R. , Wickstrom Eric , Freeman Theresa A. , Composto Russell J. , Ducheyne Paul , Shapiro Irving M. , Hickok Noreen J. , Adams Christopher S.
Published: April 2007

Periprosthetic infection is a devastating consequence of implant insertion and can arise from hematogenous sources or surgical contamination. Microbes can preferentially colonize the implant surface and, by forming a biofilm, escape immune surveillance. We hypothesized that if an antibiotic can be tethered to a titanium alloy (Ti) surface, it will inhibit bacterial colonization, prevent biofilm formation, and avert late‐stage infection. To test this hypothesis, a Ti rod was covalently derivatized with vancomycin. Reaction efficiencies were evaluated by colorimetric and spectrophotometric measurements. The vancomycin‐modified surface was stable in aqueous solutions over extended time periods and maintained antibiotic coverage, even after press‐fit insertion into a cadaverous rat femora. When evaluated using fluorescently labeled bacteria, or by direct colony counts, the surface‐bound antibiotic prevented bacterial colonization in vitro after: (1) exposure to high levels of S. aureus; (2) extended incubation in physiological buffers; and (3) repeated bacterial challenges. Importantly, whereas the vancomycin‐derivitized pins prevented bacterial colonization, S. aureus adhered to control pins, even in the presence of concentrations of vancomycin that exceeded the strain MIC. These results demonstrate that we have effectively engineered a stable, bactericidal Ti surface. This new surface holds great promise in terms of mitigating or preventing periprosthetic infection. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:858–866, 2007
Effect of crosslinking, remelting, and aging on UHMWPE damage in a linear experimental wear model
Authors: Maher Suzanne A. , Furman Bridgette D. , Babalola Omotunde M. , Cottrell Jocelyn M. , Wright Timothy M.
Published: April 2007

The objective of this study was to establish the effect of postirradiation melting as a function of irradiation dose on the wear behavior and material characteristics of ultrahigh molecular weight polyethylene. Our hypothesis was that a low dose of irradiation followed by melting would have the same improved wear performance as is found with higher doses of irradiation, but without the disadvantages associated with reduced fracture toughness. The hypothesis was tested by measuring the wear performance (wear track area, incidence of pitting and delamination) in a linear doubly curved‐on‐flat cyclic test, material behavior (elastic modulus, fracture toughness), and aging response (density changes through the thickness) of the following materials: elevated crosslinked groups—radiated at 25, 65, and 120 kGy, melted, sterilized and aged; a melted group—melted, sterilized, and aged; and a control group—sterilized and aged. Our findings suggest that postirradiation melting, not the irradiation dose, dominates the material property changes and wear response. Melting ensured reduced modulus and therefore decreased contact stresses, superior wear performance, and good resistance to aging, even after low levels of irradiation (25 kGy). The low modulus of the 25 kGy elevated crosslinked group, coupled with increased fracture toughness compared to samples irradiated at higher doses and a resistance to aging not found in the melted group, support our hypothesis. A low dose of irradiation followed by heat treatment has the same beneficial effects in terms of improved wear performance, but without the disadvantages of reduced fracture toughness found with higher doses of irradiation. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:849–857, 2007
Quantitative assessment of scaffold and growth factor‐mediated repair of critically sized bone defects
Authors: Oest Megan E. , Dupont Kenneth M. , Kong Hyun‐Joon , Mooney David J. , Guldberg Robert E.
Published: April 2007

An 8‐mm rat segmental defect model was used to evaluate quantitatively the ability of longitudinally oriented poly(L‐lactide‐co‐D,L‐lactide) scaffolds with or without growth factors to promote bone healing. BMP‐2 and TGF‐β3, combined with RGD‐alginate hydrogel, were co‐delivered to femoral defects within the polymer scaffolds at a dose previously shown to synergistically induce ectopic mineralization. A novel modular composite implant design was used to achieve reproducible stable fixation, provide a window for longitudinal in vivo micro‐CT monitoring of 3D bone ingrowth, and allow torsional biomechanical testing of functional integration. Sequential micro‐CT analysis showed that bone ingrowth increased significantly between 4 and 16 weeks for the scaffold‐treated defects with or without growth factors, but no increase with time was observed in empty defect controls. Treatment with scaffold alone improved defect stability at 16 weeks compared to nontreatment, but did not achieve bone union or restoration of mechanical function. Augmentation of scaffolds with BMP‐2 and TGF‐β3 significantly increased bone formation at both 4 and 16 weeks compared to nontreatment, but only produced bone bridging of the defect region in two of six cases. Histological evaluation indicated that bone formed first at the periphery of the scaffolds, followed by more limited mineral deposition within the scaffold interior, suggesting that the cells participating in the initial healing response were primarily derived from periosteum. This study introduces a challenging segmental defect model that facilitates quantitative evaluation of strategies to repair critically sized bone defects. Healing of the defect region was improved by implanting structural polymeric scaffolds infused with growth factors incorporated within RGD‐alginate. However, functional integration of the constructs appeared limited by continued presence of slow‐degrading scaffolds and suboptimal dose or delivery of osteoinductive signals. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:941–950, 2007
Self‐Assembled Structures in Block Copolymer Blends: SAXS, SANS and TEM Study
Authors: Holoubek Jaroslav , Baldrian Josef , Lal Jyotsana
Published: April 2007

Phenomena associated with the order‐disorder transition, microdomain morphology and phase behavior of a deuterated block copolymer (BCP) blend I/II (where I is dPS‐block‐dPMMA and II is dPS‐block‐PI) were studied by SAXS, SANS and TEM. The studied, almost symmetric, copolymers differ essentially in microdomain morphology. One of them (I) is in disordered microdomain state, while the other (II) displays lamellar morphology at ordinary temperatures. Self‐assembled structures in blends were investigated as a function of concentration of the added microphase‐separated copolymer and temperature. The ODT positions were located in all the blends, the position of ODT depending only slightly on the concentration of the ordered copolymer. A systematic increase in long period D of the lamellar phase is observed with the growing content of the disordered copolymer. The evaluation of TEM shows the gradual diminishing of macrophase separated regions of disordered copolymer I with growing content of the lamellar copolymer II.

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Initiator Efficiency of tert‐Alkyl Peroxyesters in High‐Pressure Ethene Polymerization
Authors: Buback Michael , Fischer Bart , Hinrichs Stefan , Jauer Stephan , Meijer John , Sandmann Johannes
Published: April 2007

High‐pressure ethene polymerizations using thirteen tert‐alkyl peroxyester initiators, RC(CH3)2OOCOR′ (with R = methyl, ethyl, neo‐pentyl, tert‐butyl and R′ = methyl, i‐propyl, propyl, butyl, tert‐butyl, 2‐heptyl) have been carried out in a CSTR. The initiator efficiency f has been determined for each peroxyester at 2 000 bar over a range of temperatures, partly up to 250 °C. The highest initiator efficiencies, up to about f = 0.9, are observed for tert‐butyl peroxyesters, in which the R' species is a primary radical, as e.g., with tert‐butyl peroxypentanoate and tert‐butyl peroxyacetate. The lowest efficiency value, of about f = 0.37, occurs with tert‐butyl peroxypivalate. The radicals from initiator decomposition, R′COO· and RC(CH3)2O., may undergo β‐scission reactions to produce R′ radicals by decarboxylation and R radicals by “deacetonization”, respectively. In‐cage termination reactions between oxygen‐centered and carbon‐centered radicals essentially control initiator efficiency.

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Chemoprevention of rat mammary carcinogenesis by black tea polyphenols: Modulation of xenobiotic‐metabolizing enzymes, oxidative stress, cell proliferation, apoptosis, and angiogenesis
Authors: Kumaraguruparan R. , Seshagiri P.B. , Hara Y. , Nagini S.
Published: April 2007

Chemoprevention of dietary constituents has emerged as a cost‐effective approach to control the incidence of breast cancer. The present study was therefore designed to evaluate the chemopreventive efficacy of black tea polyphenols (Polyphenon‐B) during the preinitiation phase of 7,12‐dimethylbenz[a]anthracene (DMBA) induced mammary carcinogenesis using xenobiotic‐metabolizing enzymes, cellular redox status, cell proliferation, apoptosis, and angiogenesis as biomarkers of chemoprevention. Intragastric administration of DMBA induced adenocarcinomas that showed enhanced activities of phase I carcinogen activation and phase II detoxification enzymes with increased lipid and protein oxidation and decrease in antioxidant status. This was associated with increased cell proliferation, angiogenesis, and evasion of apoptosis as revealed by upregulation of proliferating cell nuclear antigen (PCNA), Bcl‐2, and vascular endothelial growth factor (VEGF), and downregulation of Bax, caspase 3, and poly(ADP‐ribose) polymerase (PARP). Dietary administration of Polyphenon‐B effectively suppressed the incidence of mammary tumors as evidenced by modulation of xenobiotic‐metabolizing enzymes and oxidant–antioxidant status, inhibition of cell proliferation and angiogenesis, and induction of apoptosis. The present study provides evidence that Polyphenon‐B exerts multifunctional inhibitory effects on DMBA‐induced mammary carcinogenesis and suggests that it can be developed as a potential chemopreventive agent. © 2007 Wiley‐Liss, Inc.
Identifying incident cases of parkinsonism among veterans using a tertiary medical center
Authors: White Donna , Moore Suzanne , Waring Stephen , Cook Karon , Lai Eugene
Published: April 2007

To better understand the impact of incident Parkinson's disease (PD) on the Veteran's Health Administration (VHA) and to develop methods applicable to future epidemiological research, we performed a medical record review study at a tertiary referral VHA medical center. Searching the local data base, we identified 782 veterans with diagnostic codes for PD or secondary parkinsonism (SP) between 1998 and 2000. Based on structured medical record review, a movement disorders specialist confirmed diagnoses for incident parkinsonism cases. Among the 782, 191 incident parkinsonism cases were identified (100 PD, 75 SP, and 16 Parkinson's Plus). Incident PD cases were older at diagnosis (74.5 vs. 70.4 yr; P < 0.05) and more likely to be white (81% vs. 62; P < 0.07) than incident SP cases. Diagnostic codes were insufficient to distinguish between incident PD and SP (positive predictive value, 57% and 39%, respectively), and VHA sources failed to identify 21% of confirmed deaths among the incident PD cohort by November 2004. Although the large number of incident cases identified suggests PD is an important cause of disability among elderly VHA users, observed limitations of VHA sources for identifying incident PD cases and determining their vital status should be considered when designing future studies. © 2006 Movement Disorder Society
Defining mild cognitive impairment in Parkinson's disease
Authors: Caviness John N. , Driver‐Dunckley Erika , Connor Donald J. , Sabbagh Marwan N. , Hentz Joseph G. , Noble Brie , Evidente Virgilio Gerald H. , Shill Holly A. , Adler Charles H.
Published: April 2007

Our purpose was to characterize a state of mild cognitive impairment (MCI) in Parkinson's disease (PD) (PD‐MCI) that would be analogous to the MCI that is posited as a precursor of Alzheimer's disease (AD). We categorized 86 PD subjects in a brain bank population as either cognitively normal (PD‐CogNL), PD‐MCI using criteria that included a 1.5 standard deviation or greater deficit upon neuropsychological testing consistently across at least one cognitive domain without dementia, and PD dementia (PD‐D) using DSM‐IV criteria. Twenty‐one percent of our PD sample met criteria for PD‐MCI, 62% were PD‐CogNL, and 17% had PD‐D. The mean duration of PD and MMSE scores of the PD‐MCI group were intermediate and significantly different from both PD‐CogNL and PD‐D. The cognitive domain most frequently abnormal in PD‐MCI was frontal/executive dysfunction followed by amnestic deficit. Single domain PD‐MCI was more common than PD‐MCI involving multiple domains. We conclude that a stage of clinical cognitive impairment in PD exists between PD‐CogNL and PD‐D, and it may be defined by applying criteria similar to the MCI that is posited as a precursor of AD. Defining PD‐MCI offers an opportunity for further study of cognitive impairment in PD and targets for earlier therapeutic intervention. © 2007 Movement Disorder Society
Entanglement Tightening and Stress Relaxation
Authors: O'Donnell Robert G. , Edward Graham H.
Published: April 2007

The contribution of entanglements to the modulus of a time independent polymer is satisfactorily accounted for by the C2/λ term in the Mooney‐Rivlin equation. On the other hand, the role of entanglements in time dependent polymers is less evident and seems to give rise to a non‐linear Mooney plot. A model is introduced which considers an entanglement as a topological knot that tightens with initial deformation and subsequently inhibits chain slippage. The observed maximum in a Mooney plot at small values of λ is predicted, and the experimental data of plasticised PVC polybutadiene and styrenebutadiene copolymer are fitted reasonably well.
Processing Aids: The Effect of Polymethyl Methacrylate on the Fusion of Rigid Poly(vinyl chloride)
Authors: Kosior E. I. , Stachurski Z. H.
Published: April 2007

The fusion process of a PVC dryblend, both with and without a PMMA processing aid, was studied in a Brabender Plasticorder over a range of mixer temperatures. charge masses and rotor speeds. The progress of fusion was monitored by the examination of the morphology of the PVC samples taken during different stages of the fusion process. The technique of examining the acetone‐swollen samples by optical microscopy before and after shearing,1 provided an insight to the mechanism of action of the PMMA processing aid. The study established that the PMMA processing aid modified both the inter‐grain coefficient of friction and the packed density which had a significant effect on the initiation of the fusion process. The fusion process of both PVC compounds, i.e. with and without PMMA processing aid, was shown to proceed via a comminution mechanism, where the PVC grains were randomly broken into sub‐grains and primary particle agglomerates. Concurrent with this breakdown, the cohesion of PVC agglomerates was observed.
An Experimental Study of the Thermodynamics of Rubber in Extension and Torsion
Authors: Mohsin Mahmood A. , Berry John P. , Treloar Leslie R. G.
Published: April 2007

The stress‐strain properties of three different rubbers have been measured using two different techniques, in order to evaluate the relative internal energy contribution to the total stress fe/f and the corresponding value of Me/M over a range of strain and temperatures. Two different experimental techniques have been designed; one is to allow measurement in simple extension of the length of a rubber sample in relation to the temperature at constant force, and the other is to measure the variation of torsional couple M in a cylinder of rubber (subjected to combined torsion about the axis and extension in the axial direction) with temperature. The thermoelastic results obtained for natural rubber and butyl rubber do not contain any surprising features, and are found to be in good agreement with other reported experimental results for these rubbers. Values of fe/f and Me/M obtained for cis‐trans polybutadiene rubber show different trends between the two techniques.
Homogeneous Polymerisation of Methylmethacrylate Initiated by Alkali Metal Salts of Methanol and t‐Butyl Alcohol in the Presence of Cryptands and Macrocyclic Crown Ether Compounds
Authors: Viguier Michel , Collet André , Schué François , Mula Bernard
Published: April 2007

The polymerisation of methylmethacrylate initiated by alkali alkoxides is greatly promoted in the presence of macrocyclic compounds, cryptands and crown ethers. The solubility in toluene and the reactivity of alkoxides is enhanced by these complexing agents. Polymerisations have been carried out in a non‐polar solvent in the homogeneous phase.
Reactions of Living Polytetrahydrofuran with Amines V ‐ Tertiary Amine Terminated Polybutadienes; The Synthesis of Novel Ionically Linked Block Copolymers
Authors: Hurley J. , Richards D. H. , Stewart M. J.
Published: April 2007

The reactions of mono‐ and difunctional tertiary amine ended polybutadienes with mono‐ and difunctional living cationic poly THF have been studied. It is shown that the reaction to form quaternary ammonium linking groups takes place rapidly in all cases, and AB. ABA, BAB and (AB) block copolymers have been prepared. The efficiency of the process is extremely high and the degree of conversion is essentially controlled by the efficiency with which the terminal tertiary amine groups can be introduced on to the polybutadiene. The block copolymers show anomalous behaviour on gel permeation chromatography columns and this has been related to a specific interaction of the created ionic groups with polar species on the column packing. This effect is greatest with (AB) block copolymers where substantial proportions are retained indefinitely on the columns.
The Initial Thermal Stability of Poly(vinyl chloride)
Authors: Gracia Martinez J. A. , Gutierrez Fernandez F. , Manley T. R.
Published: April 2007

The use of a fluidised bed reactor and a conductivity cell provide a technique for the study of degradation of PVC with greatly increased sensitivity. The kinetics of the reaction may be studied at 350 K and for small (1%) amounts of degradation. The effects of diffusion within the particles may be distinguished from that of diffusion in the surrounding atmosphere. The influence of temperature and particle size and sintering were examined. The catalytic effect of HCl was confirmed and an apparent activation energy of 29 kcal mol−1 was observed.
Recent Studies of Physical Properties of Highly Oriented Polyethylene
Authors: Ward Ian M.
Published: April 2007

Recent studies of the structure and properties of ultra high modulus polyethylenes are presented. The physical properties received include dynamic mechanical behaviour, creep, shrinkage, shrinkage force, melting behaviour, thermal expansion and barrier properties.
Polymeric Photoinitiators Containing Side‐chain Ketoaromatic Moieties for Fast Ultraviolet Initiated Polymerisation of Acrylic Monomers
Authors: Carlini Carlo
Published: April 2007

The synthesis of polymeric photoinitiators having side‐chain cyclohexylphenylketone as well as benzophenone moieties at different distances from the backbone is described. Study of the activity of the former systems, in the ultraviolet initiated polymerisation of acrylic monomers, indicates that a remarkable increase in the polymerisation rate is observed when the cyclohexylphenylketone chromophore is attached to the main chain through an ethereal linkage rather than an ester group. In the case of the latter systems, considerable improvement is observed in the photoinitiating activity with respect to the corresponding low molecular weight model compounds in the polymerisation of acrylic monomers. Moreover, in general the copolymers of benzophenone‐containing monomers show higher activity than the corresponding homopolymers. These results are discussed in terms of photoexcitation energy migration along the polymer chain, as well as of intramolecular hydrogen abstraction from both main and side chains. This last occurrence seems to be the main activation process, as suggested by a strict correlation between activity and hydrogen‐donating properties of the co‐units in the copolymers, Photophysical evidence supporting this point is also reported. Finally, the synthesis of polymeric photoinitiators, containing both benzophenone and tertiary amine groups in the same macromolecule, has been accomplished via copolymerisation of 4‐acryloxybenzophenone with 4‐(N,N‐dimethylamino)styrene. Preliminary data concerning photoinitiating activity of these last copolymers indicate that conformational mobility affects the formation capability of exciplexes and then the activity itself.
Behaviour of Composites Used in the Confinement of Nuclear Wastes 1 ‐ Water Absorption of Polymer Matrices
Authors: Nicaise E. , Gandini A. , Cheradame H.
Published: April 2007

The diffusion of water into typical epoxide and polyester materials has been studied as a function of temperature, temperature cycles and polymer structure. A reversible uptake characterised by a diffusion coefficient and an equilibrium absorption was accompanied by an irreversible water uptake due to hydrolysis. Polyesters showed a pronounced tendency to degradation, particularly above room temperature. This preliminary investigation was conducted within the broader scope of a study dealing with the feasibility of embedding nuclear wastes in polymer matrices. The results obtained thus far are encouraging, notably with epoxide networks.
Mechanical Properties of Alkyl Isocyanate Modified Scots Pine Wood Surfaces
Authors: Banks William B. , Jones Gwynn Lloyd
Published: April 2007

Thin longitudinal sections (100 μm thick) were reacted with butyl isocyanate and octadecyl isocyanate under dry conditions. Weight gain and nitrogen analysis demonstrated reaction to degree of substitution about 0.9 (based on published wood cell wall analytical data). Infrared spectra data gave good evidence for the formation of carbamate ester (urethane bonds). Up to weight gain of about 30% no practically significant loss of tensile strength or toughness was observed. Above this level, strength and toughness was observed to fall as a function of weight increase, similarly with both reagents. Over the range examined the precise degree of substitution (loss of hydroxyl functionality) appeared to have no direct effect on mechanical properties. The strength losses seem to be related to cell wall rupture resulting from excessive swelling occurring at the higher levels of reaction.
Application of New Radiochemical Methods to the Study of the Cure of Epoxies by Various Imidazoles
Authors: Jones John R. , Poncipe Carlo , Barton John M. , Wright William W.
Published: April 2007

The reaction between phenylglycidyl ether and a number of substituted imidazoles has been investigated using a combination of tritium nuclear magnetic resonance spectroscopy and radio‐high performance liquid chromatography, two methods that have not been used previously in this area. For more volatile catalysts such as aromatic amines radio‐gas chromatography can be employed to good effect.
Use of the Exponential Model of Enzyme Decay to Plan a Strategy for Enzymatic Batch Reactions and to Assess the Industrial Applicability of Immobilised Enzyme Preparations
Authors: Cardoso Joaquim Pereira
Published: April 2007

This paper is concerned with the development of a model to plan a strategy for an enzymatic batch process whereby the enzyme is subjected to deactivation as described by the exponential (first‐order) decay model. The particular system used was the enzymatic hydrolysis of penicillin to 6‐aminopenicillanic acid, but the model can be utilised with other batch systems, provided that decay of the immobilised enzyme preparation is described by the exponential decay model. The model developed is eminently practical and simple, and several examples of its application are given. Experimental data obtained in a small pilot plant batch recirculated reactor could, on average, be well fitted by this model.
Borides and Silicides ‐ New Chemistry and Applications
Authors: Aylett Bernard J.
Published: April 2007

A general survey is presented of the preparation, physical and chemical properties, and structural patterns of transition metal borides and silicides. The appropriateness of their description as inorganic homopolymers stabilised by electron transfer from metal centres is discussed. Finally, applications are outlined, with particular reference to the fabrication of thin films and their use in advanced microelectronic devices.
Polymerization of ethyl 2‐cyanoacrylate in the presence of poly(butadiene‐co‐acrylonitrile)
Authors: Dikov Valentin K. , Kotzev Dimitar L. , Kabaivanov Vladimir S.
Published: April 2007

Radical graft copolymers of ethyl 2‐cyanoacrylate on to poly(butadiene‐co‐acrylonitrile), were prepared and characterized by infrared spectroscopy. Simultaneous homopolymerization of ethyl 2‐cyanoacrylate also occurred. The polymerization of ethyl 2‐cyanoacrylate is significantly affected by the presence of the pre‐formed dissolved elastomer, the overall activation energies in the presence and absence of elastomer being 80.8 ± 0.4 kJ mol−1 and 77.0 ± 0.4 kJ mol−1, respectively. In each case the reaction was first‐order with respect to the monomer.
Particulate stabilisers for drops in suspension polymerisation: Use of a wax model
Authors: Brooks Brian W. , Bygate Fiona , Lane Andrew C.
Published: April 2007

Finely divided inorganic solids can be used for drop stabilisation in suspension polymerisation. In order to clarify the role of these solids, experiments have been carried out using a model system in which wax drops were dispersed in water in the presence of magnesium hydroxide. Drop sizes were reduced if the hydroxide was precipitated in situ before dispersion of the wax. As the loading of this precipitate increased, the average drop size passed through a minimum. The presence of a surfactant modified the effect of the hydroxide. Electrolyte, which is formed in the precipitation reaction, also influences the drop size. The separate effects of solid hydroxide, surfactant and electrolyte are not additive. There is some evidence for a nucleating effect which may not be desirable in suspension polymerisation.
Magnetic and optical properties of single crystals of transition metal doped ZnO
Authors: Kane M. H. , Fenwick W. E. , Strassburg M. , Nemeth B. , Varatharajan R. , Song Q. , Keeble D. J. , El‐Mkami Hassane , Smith G. M. , Zhang Z. J. , Nause J. , Summers C. J. , Ferguson I. T.
Published: April 2007

Considerable effort has been devoted to the study of transition metal doped zinc oxide following various theoretical predictions of room temperature ferromagnetism in these materials. Near equilibrium growth techniques may be suitable for the production of dilute transition metal doped ZnO because the transition metal solubility in ZnO can be relatively high. This work reports on the optical, structural, and magnetic properties of single crystals of Co‐ and Mn‐doped ZnO grown by a modified melt‐growth technique. X‐ray diffraction reveals that the as grown crystals are pure single crystals with no second phases. Mn doping up to 5% results in an increase in c‐axis lattice parameter (5.207 Å to 5.211 Å), and X‐ray linewidths (78 arcsec to 252 arcsec) at doping levels of 5% Mn. Optical transmission shows distinct absorption spectra related to the color of the Zn1–x TMx O sample resulting from interatomic transitions within the divalent transition metal ion. Electron paramagnetic resonance confirms the divalent nature of the substitutional transition metal ions. Raman spectroscopy shows the predominantly the E2 (high) peak at 407 cm–1, but with increasing doping shows additional disorder‐related modes. The magnetic behavior reveals a paramagnetic behavior at all temperatures for both Mn‐ and Co‐doped ZnO up to transition metal doping levels of 5% and 3% respectively. The dominant exchange mechanism in the Mn‐ and Co‐doped ZnO crystals is found to be antiferromagnetic superexchange. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical observation of discrete well width fluctuations in wide band gap III‐nitride quantum wells
Authors: Haratizadeh H. , Monemar B. , Paskov Plamen P. , Holtz Per Olof , Valcheva E. , Persson P. , Iwaya M. , Kamiyama S. , Amano H. , Akasaki I.
Published: April 2007

A detailed observation of discrete well width fluctuations via localized excitons in the photoluminescence (PL) spectra of MOCVD‐grown undoped GaN/Al0.07Ga0.93N multiple quantum wells (MQWs) has been reported. Doublet excitonic features with a distance varying between 10 and 25 meV for different well widths (1.5 to 4.5 nm) are observed in the PL spectra. They are explained in terms of discrete well width variations by onec‐lattice parameter, i.e. two GaN monolayers. By mapping the PL measurements across the samples with different excitation spot size, it is shown that the extension of areas with a constant well width is less than 1 μm2. TEM pictures give evidence of interface roughness, although the contrast is weak at this low Al composition. In addition we observe a long‐range variation of the PL peak position across the sample, interpreted as a fluctuation in Al composition in the barriers. The residual broadening of an excitonic peak (apart from the splitting related to well width fluctuations) is about 10 meV, somewhat larger for larger well widths, and is mainly ascribed to hole localisation potentials in the QWs. Additional broadening occurs in the MQWs due to inequivalent properties of each QW within the excitation spot. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)