bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biomechanical and surface physico‐chemical analyses of used osteosynthesis plates and screws—Potential for reuse in developing countries?
Authors: Magetsari Rahadyan , van der Houwen Eduard B. , Bakker Martine T. J. , van der Mei Henny C. , Verkerke Gijsbertus J. , Rakhorst Gerhard , Hilmy Chehab R. , van Horn Jim R. , Busscher Henk J. 
Published: May 2006

AbstractReprocessing of single‐use devices is an upcoming issue in the Western world, but has been for many years in developing countries. In developing countries, the number of bone fractures due to traffic or industrial accidents is high. Patients often need an osteosynthesis with plates and screws, but most patients, however, cannot afford this because of the costs involved and have to rely on the application of used plates and screws. This study aims to determine whether used plates can be safely reused in another patient from a biomechanical, surface physico‐chemical, and biological point‐of‐view. Osteosynthesis plates weakened in a predictable way during use, regardless of the history, presumably because tests were conducted under extreme conditions in the absence of clinically applied load‐sharing between bone and plate. Surface physico‐chemical analyses indicated that used plates and screws were more hydrophilic than new ones; had increased amounts of calcium‐phosphates at their surfaces and possessed higher number of scratches. Pitting corrosion could be seen on SEM micrographs. Simple cleaning methods, as available in developing countries, including toothbrush, water, detergent and bleach yielded elemental surface compositions, and hydrophobicities similar to those of new ones, while biologically thus cleaned screws were not cytotoxic according to ISO‐10993–5 and endotoxin release according to USP‐27‐NF‐22 was within the requirements of the FDA. It is concluded that the reuse of osteosynthesis plates and screws are not necessarily unsafe, although preferably a register should be kept of all previous users to limit the number of reuses as mechanical weakening does occur. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Changes in scattering and absorption properties of esthetic filling materials after aging
Authors: Lee Yong‐Keun , Lim Bum‐Soon , Rhee Sang‐Hoon , Yang Hyeong‐Cheol , Lim Yong‐Kyu 
Published: May 2006

AbstractObjectivesAssuming that color changes after aging are related to changes in translucency of materials, the purpose of the present study was to determine the correlation between the changes in color and the changes in scattering and absorption properties after accelerated aging with representative dental esthetic restorative materials: glass ionomer, resin‐modified glass ionomer, compomer, and resin composite.MethodsColor was measured according to the CIELAB color scale in the transmittance and reflectance modes and used to calculate changes in color (ΔE*ab), color coordinates (ΔL*, Δa*, and Δb*), translucency parameter (ΔTP), scattering coefficient (ΔS), absorption coefficient (ΔK), and light reflectivity (ΔRI) after accelerated aging. Simple correlations between each pair of the changes in optical values were calculated, and multiple regression analysis was used to determine the parameters influencing the changes in color and color coordinates (p = 0.05).ResultsIn the resin composite and compomer, ΔS, ΔK, and ΔRI values were approximately zero, whereas ΔS was as high as 8.9 in the glass ionomer. For most comparisons, correlation coefficient (r) was between 0.700 and 0.997. ΔL* was found to have a major influence on color changes, and ΔS, ΔTP, and ΔRI influenced ΔL*. Therefore, changes in scattering and absorption properties, after aging, were closely correlated with changes in color and color coordinates, especially in glass ionomer‐based filling materials. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Surface modification of titanium‐based alloys with bioactive molecules using electrochemically fixed nucleic acids
Authors: Michael J. , Beutner R. , Hempel U. , Scharnweber D. , Worch H. , Schwenzer B. 
Published: May 2006

AbstractA new method of surface modification for titanium (alloys) with bioactive molecules was developed with the intention of providing a new basis of implant adaptation for particular requirements of certain medical indications. Nucleic acid single strands are fixed electrochemically via their termini (regiospecifically) by growing an oxide layer on Ti6Al7Nb anodically. It could be shown that they are accessible to subsequent hybridization with complementary strands at physiological pH. Amount of nucleic acids immobilized and hybridized were determined radioanalytically using 32P‐labelled nucleic acids. Stable fixation was attained at and above potentials of 4 VSCE. Up to 4 pmol/cm2 of nucleic acid single strands could be immobilized and hybridization efficiencies up to 1.0 were reached. Hybridization efficiency was found to depend on surface density of immobilized oligonucleotides, while hybridization rates increased when MgCl2 was added. A conjugate consisting of an oligonucleotide complementary to the immobilized strand and the hexapeptide GRGDSP with RGD as an integrin recognition site was synthesized. This conjugate was able to bind to integrins on osteoblasts. It was shown that this conjugate binds to the anchor strand fixed on Ti6Al7Nb to an extent comparable with the unconjugated complementary strand. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Bovine prion (PrP) and Doppel (Dpl) proteins expression after in vitro leukocyte activation or Dpl/PrP blocking
Authors: Paltrinieri Saverio , Spagnolo Valentina , Giordano Alessia , Gelmetti Daniela , Comazzi Stefano 
Published: May 2006

AbstractIt has been postulated that Doppel (Dpl) and Prion (PrP) proteins have yet undetermined interactions, since Dpl is overexpressed in transgenic PrP‐deficient mice. In this study we investigated the expression levels of Dpl and PrP on lymphocytes, monocytes and neutrophils (PMNs) isolated from bovine blood and incubated (2 and 18 h) with TNFα, IL‐1, IL‐2, IL‐8, C5a, IFNγ, anti‐PrP, and anti‐Dpl antibodies by flow cytometry. The isolation procedures yielded cell populations with high purity, viability and recovery rates. After 2 h incubation, expression of PrP or Dpl was altered only in PMNs. These cells overexpressed PrP when incubated with TNFα and IFNγ, and both PrP and Dpl when incubated with C5a; incubation with TNFα, IL‐8 and IFNγ led to down‐regulation of Dpl. Lymphocytes incubated for 18 h with IL‐2 and with IFNγ overexpressed Dpl. Incubation with the anti‐PrP antibody induced down‐regulation of Dpl in PMNs after 2 h and overexpression of Dpl in lymphocytes after 18 h. The differences recorded after 2 h were likely due to redistribution of pre‐existing PrP or Dpl molecules, while those seen at 18 h were most probably due to increased protein synthesis. The variations seen using the different activators depend on different receptors and/or signaling pathways. These results demonstrate that is possible to alter the expression of Dpl and PrP in blood cells in vitro by incubation with either cytokines or anti‐PrP antibodies. This opens an interesting opportunity to study the biology of these proteins using in vitro systems. J. Cell. Physiol. 208: 446–450, 2006. © 2006 Wiley‐Liss, Inc.
Robust stochastic seasonal precipitation scenarios
Authors: Kioutsioukis Ioannis , Rapsomanikis Spyridon , Loupa Rea 
Published: May 2006

AbstractIn this paper, a stochastic statistical forecasting methodology is employed for long‐term predictions of winter precipitation over Greece. Lagged climatic indices and North Atlantic (NA) sea‐level pressure (SLP) field are explored as potential predictors of the teleconnection. Rather than employing traditional stationary models, two dynamic regression‐modelling schemes are analysed and validated and their parameter variation is interpreted. Dynamic regression models, in contrast to static (constant parameter) regression models, have time variable parameters (TVPs) evaluated through recursive optimisation and are suitable for analysis of non‐stationary phenomena like most atmospheric processes.The analysis of the spectrum with non‐stationary models points out that the most influential seasonal components of the winter precipitation anomalies have periods of 14 and 3.5 years, explain 40% of its variance, possess significant amplitude change and correlate significantly with the North Atlantic Oscillation Index Anomaly (NAOIA) and Southern Oscillation Index Anomaly, indicating their climatic origin. Furthermore, the forecasting skill of the dynamic models (R2 = 0.71), in addition to reproducing the peaks, was found superior even to the hindcasting skill of the stationary model (R2 = 0.55). Copyright © 2006 Royal Meteorological Society
Comparative study of degenerate four‐wave mixing and cavity ringdown signal intensities of formaldehyde in a molecular beam
Authors: Tulej M. , Meisinger M. , Knopp G. , Walser A. M. , Beaud P. , Gerber T. , Radi P. P. 
Published: May 2006

AbstractA comparison of degenerate four‐wave mixing (DFWM) and cavity ring‐down (CRD) spectroscopy is made on jet‐cooled formaldehyde under identical expansion conditions. We show that both methods are applicable to the low‐density environment of a molecular beam. However, a slightly superior signal‐to‐noise ratio for the background‐free DFWM method is observed for our experimental configurations. Absorption spectra simulated by applying an asymmetric rotor model are used to deduce Boltzmann temperatures of the rotational population distribution by a nonlinear least‐squares fit to the experimental data. In addition, partial interconversion of the nuclear spin upon supersonic expansion is observed. Consequently, a second fit parameter, describing the para/ortho concentration ratio in the molecular beam, is introduced. The resulting simulated spectra are in favorable agreement with the relative CRD intensities. A simple model for the reduction of the DFWM signal intensities to population is applied yielding absorption‐like spectra in accordance with both the simulations and the CRD measurements. We conclude that DFWM spectroscopy is applicable to deduce population distributions of an asymmetric rotor molecule under free‐jet conditions. Copyright © 2006 John Wiley & Sons, Ltd.
Coherent bichromatic spectroscopy of Rb vapor with a femtosecond laser
Authors: Akimov A. V. , Matveev A. N. , Sokolov A. V. , Tereshenko E. O. , Kondratjev D. A. , Sorokin V. N. , Kanorsky S. I. , Kolachevsky N. N. 
Published: May 2006

AbstractWe experimentally studied the narrow resonances of coherent population trapping (CPT) in a rubidium vapor cell with the help of a phase‐coherent bichromatic light source based on a mode‐locked femtosecond laser. We investigated the dependence of the contrast and the width of CPT resonance on the light power, as well as the sensitivity of the shape of the resonance to a magnetic field. Prospects of using the novel bichromatic source for phase‐coherent Raman spectroscopy of CPT resonances in atomic systems with a large energy separation of the lower levels are discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Kinetics and mechanism of the oxidation of acetylacetone by permanganate ion
Authors: Jáky Miklós , Szammer János , Simon‐Trompler Edit 
Published: May 2006

AbstractThe kinetics and mechanism of permanganate ion oxidation of acetylacetone (Acac) was studied in acidic and alkaline media. The rate constants for keto, enol, and enolate anions were determined and discussed. Delocalization of the π‐electrons of the double bond by conjugation results in a slower oxidation rate of enol than can be usually observed for unsaturated compounds. In the case of the keto form, the acid‐catalyzed nucleophilic attack of permanganate ion occurs on the carbonyl‐C atom. For enolate anion a mechanism with basis‐catalyzed electron abstraction is suggested. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 444–450, 2006
Biodegradable Network Elastomeric Polyesters from Multifunctional Aliphatic Carboxylic Acids and Poly(ε‐caprolactone) Diols
Authors: Nagata Minoru , Kato Keisuke , Sakai Wataru , Tsutsumi Naoto 
Published: May 2006

AbstractSummary: Biodegradable elastomeric network polyesters were prepared from multifunctional aliphatic carboxylic acids such as tricarballylic acid (Yt) or meso‐1,2,3,4‐butanetetracarboxylic acid (Xb) and poly(ε‐caprolactone) (PCL) diols with molecular weights of 530, 1 250 and 2 000 g · mol−1. Prepolymers prepared by a melt polycondensation were cast from DMF solution and postpolymerized at 280 °C for various periods of times to form a network. The resultant films were transparent, flexible and insoluble in organic solvents. The network polyesters obtained were characterized by IR absorption spectra, WAXS, density measurement, DSC, and tensile test. YtPCL1250, and XbPCL1250 network polyester films showed good elastomeric properties with high ultimate elongation (540–590%), and low Young's modulus (2.5–3.3 MPa). The enzymatic degradation was estimated by the weight loss of network films in a buffer solution with Rhizopus delemar lipase at 37 °C. The degree and rate of degradation were significantly affected by the molecular weight of PCL diol, chemical structures of multifunctional aliphatic carboxylic acids and the morphology of network films. The changes in the solid states of network films during the degradation were also estimated by the results of DSC and WAXS.
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Liquid Pool Copolymerization of Propylene/1‐Butene with a MgCl2‐Supported Ziegler‐Natta Catalyst
Authors: Silva Fabricio M. , Melo Príamo A. , Nele Márcio , Lima Enrique L. , Pinto José Carlos 
Published: May 2006

AbstractSummary: Liquid pool propylene/1‐butene copolymerizations were carried out in a batch reactor with a high activity Ziegler‐Natta catalyst system. Experimental runs were performed to evaluate the effect of the 1‐butene content on the crystallinity and melt temperature of the polymer resins. According to the results, 1‐butene can be significantly incorporated into the polymer chain at high polymerization rates over the whole range of copolymer compositions, leading to a decrease in the melting temperature (Tm) of the polymer, when compared to the poly(propylene) homopolymer, allowing for reduction of the sealing initiation temperature. It was observed by GPC and MFI measurements that the average molecular weights and the polydispersity index of the copolymer significantly decreased when compared to the ones obtained from poly(propylene). Despite high polymerization rates, polymer particles with good morphological features were produced in all cases. It was also observed that the absence of an external electron donor led to low crystallinity values for both the poly(propylene) homopolymer and for copolymers with different fractions of 1‐butene, when compared to literature values frequently reported for polymer resins based on 1‐butene and propylene. The obtained results indicate that a family of bulk propylene/1‐butene copolymer grades can be successfully developed for packaging and film applications.Surface morphology and molecular weight distribution (deconvoluted into Schulz‐Flory distributions) of the propylene/1‐butene copolymer.imageSurface morphology and molecular weight distribution (deconvoluted into Schulz‐Flory distributions) of the propylene/1‐butene copolymer.
Occurrence of mycotoxins (ochratoxin A, deoxynivalenol) and toxigenic fungi in Moroccan wheat grains: impact of ecological factors on the growth and ochratoxin A production
Authors: Hajjaji Abdelouahed , El Otmani Mostafa , Bouya Driss , Bouseta Amina , Mathieu Florence , Collin Sonia , Lebrihi Ahmed 
Published: May 2006

AbstractThe aim of the present work was to evaluate the contamination of some samples, taken from Moroccan wheat grains, by ochratoxin A (OTA), deoxynivalenol (DON) and the associated toxigenic fungi. Moreover, we focused on the influence of environmental factors on both the growth and OTA production by three strains of Aspergillus. The results showed that only few samples were contaminated by the two mycotoxins (2 samples for OTA and 7 for DON). The main isolated fungi belong to the Aspergillus, Penicillium and Fusarium genus; 74 Aspergillus and 28 Penicillium isolates were tested for their ability to produce OTA. Only 2 A. alliaceus and 14 A. niger were able to synthesize OTA. However, none of Penicillium isolates can produce this toxin under the conditions mentioned. In respect of the effects of the temperature and water activity (aw), the optimal conditions for the growth and OTA production were different. While the optimal conditions of growth for A. alliaceus and A. terreus are 30°C and 0.98 aw, A. niger prefered 0.93–0.95 aw at 25°C, whereas the optimal production of OTA was observed at 30°C for both A. alliaceus and A. niger at 0.93 and 0.99 aw, respectively.
Modulation of neurosteroid production in human neuroblastoma cells by Alzheimer's disease key proteins
Authors: Schaeffer Véronique , Patte‐Mensah Christine , Eckert Anne , Mensah‐Nyagan Ayikoe G. 
Published: May 2006

AbstractStudies performed with animals suggest neurosteroid involvement in neuroprotection. However in humans, the role of neurosteroidogenesis in the regulation of degenerative processes is unknown. To determine whether cellular factors intervening in degenerative mechanisms may interfere with the process of neurosteroidogenesis in humans, we combined pulse‐chase experiments with HPLC and continuous flow scintillation detection to compare neurosteroid production in normal and transfected SH‐SY5Y cells with key proteins involved in Alzheimer's disease (AD). Microscope analyses revealed that cell morphology was unchanged in stably transfected SH‐SY5Y cells overexpressing human native tau (hTau40), mutant tau (P301L), and wild‐type amyloid precursor protein (APPwt) compared to controls. Biochemical investigations showed that hTau40 enhanced progesterone (PROG), 17OHPROG, testosterone, and 3α‐androstanediol neosynthesis from pregnenolone. In contrast, tau with the pathogenic P301L mutation was devoid of action on neurosteroidogenesis. Overexpression of APPwt inhibited PROG formation, did not affect 17OHPROG and testosterone, but increased 3α‐androstanediol and estradiol synthesis. Extracellular treatment of control cells with aggregated amyloid peptide mimicked the action of APPwt expression on PROG but not on 3α‐androstanediol and estradiol production. Moreover, PROG biosynthesis in APPwt cells was up‐regulated in the presence of a γ‐secretase inhibitor. Our results provide the first evidence for the regulation of neurosteroid biosynthesis by key proteins involved in the etiology of AD. The data suggest that pathogenic factors may induce neurodegeneration in humans through the reduction of the synthesis of endogenous neuroprotective neurosteroids in nerve cells. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Interactions of the C2 domain of human factor V with a model membrane
Authors: Mollica Luca , Fraternali Franca , Musco Giovanna 
Published: May 2006

AbstractActivated coagulation Factor V is an important cofactor of the coagulation cascade that catalyzes the formation of the prothrombinase complex on the surface of membranes rich in phosphatidyl‐l‐serine (PS). Here we report molecular dynamics simulations of the two crystallographic structures (the open and closed conformations) of domain C2 of coagulation Factor V (FaVC2). The calculations were performed in water (1.5 ns for each conformation) and in the presence of a neutral phospholipid bilayer model (POPE; 10 ns for each conformation) in order to describe the dynamics of the free (plasma circulating) and membrane bound forms of FaVC2. Water simulations confirmed the hypothesis that the plasma circulating form is in the closed conformation. In contrast, the membrane simulations showed that both conformations are energetically compatible with membrane binding. We have investigated the mechanism, the dynamics, and the energetics of the binding process. Our data are consistent with published estimates of the immersion depth of the aromatic residues (W26 and W27), and with mutagenesis studies involving specific residues located on the spikes at the bottom of the FaVC2 structure. Electrostatic interactions between the phospholipid head groups and hydrophilic residues at the bottom of the structure play a key role in the binding process by creating a large number of hydrogen bonds that anchor the protein to the membrane. The simulations identified a stable phospholipid binding pocket reminiscent of a previously suggested PS interaction site. Our structural data could contribute to the design of potential inhibitors able to disrupt membrane association. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Microstructure of multi‐layered interphases processed by temperature‐pulsing chemical vapor infiltration
Authors: Yuan M. , Huang Zh. R. , Dong Sh. M. , Zhu Y. Zh. , Jiang D. L. 
Published: May 2006

AbstractWe demonstrate for the first time to our knowledge the method of temperature‐pulsing chemical vapour infiltration to process multilayered interphases of the carbon/silicon carbide composites. Transmission electron microscopy was employed to investigate the microstructure of the interphases. Finely alternate layered microstructures in nanoscale were proved to be prepared successfully via the route. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A randomized on–line algorithm for thek–server problem on a line
Authors: Csaba Béla , Lodha Sachin 
Published: May 2006

AbstractThek–server problemis one of the most important and well‐studied problems in the area of on–line computation. Its importance stems from the fact that it models many practical problems like multi‐level memory paging encountered in operating systems, weighted caching used in the management of web caches, head motion planning of multi‐headed disks, and robot motion planning. In this paper, we investigate its randomized version for which Θ(logk)–competitiveness is conjectured and yet hardly any <kcompetitive algorithms are known, even for the simplest of metric spaces ofO(k) size.We present a$O(n^{2/3}\log{n})$–competitive randomizedk–server algorithm against an oblivious adversary when the underlying metric space is given bynequally spaced points on a line$({\cal L}(n))$. This algorithm is <kcompetitive for$n = k + o\big(\big({k \over \log k}\big)^{3/2}\big)$. Thus, it provides a super–linear bound fornwitho(k)–competitiveness for the first time and improves the best results known so far for the range$n-k \in \big[o(k), o\big(\big({k \over \log k}\big)^{3/2}\big)\big]$on${\cal L}(n)$. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2006