bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro fracture toughness of human dentin
Authors: Imbeni V. , Nalla R. K. , Bosi C. , Kinney J. H. , Ritchie R. O. 
Published: June 2003

AbstractThe in vitro fracture toughness of human dentin has been reported to be of the order of 3 MPa√m. This result, however, is based on a single study for a single orientation, and furthermore involves notched, rather than fatigue precracked, test samples. The present study seeks to obtain an improved, lower‐bound, value of the toughness, and to show that previously reported values may be erroneously high because of the absence of a sharp crack as the stress concentrator. Specifically, the average measured critical stress intensity, Kc, for the onset of unstable fracture along an orientation perpendicular to the long axis of the tubules in dentin is found to be 1.8 MPa√m in simulated body fluid (Hanks' balanced salt solution), when tested in a three‐point bending specimen containing a (nominally) atomically sharp precrack generated during prior fatigue cycling. This is to be compared with a value of 2.7 MPa√m measured under identical experimental conditions except that the bend specimen contained a sharp machined notch (of root radius 30–50 μm). The effect of acuity of the precrack on the fracture toughness of human dentin is discussed in the context of these data. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 1–9, 2003
Biocompatibility and hemocompatibility of surface‐modified NiTi alloys
Authors: Armitage David A. , Parker Terry L. , Grant David M. 
Published: June 2003

AbstractNickel titanium (NiTi) shape memory alloys have been investigated for several years with regard to biomedical applications. However, little is known about the influences of surface modifications on the biocompatibility of these alloys. The effects of a range of surface treatments were investigated. Cytotoxicity and cytocompatibility studies with both fibroblast and endothelial cells showed no differences in the biocompatibility of any of the NiTi surfaces. The cytotoxicity and cytocompatibility of all surfaces were favorable compared to the controls. The hemolysis caused by a range of NiTi surfaces was no different from that caused by polished 316L stainless steel or polished titanium surfaces. The spreading of platelets has been linked to the thrombogenicity of materials. Platelet studies here showed a significant increase in thrombogenicity on polished NiTi surfaces compared to 316L stainless steel and pure titanium surfaces. Heat treatment of NiTi was found to significantly reduce thrombogenicity, to the level of the control. The XPS results showed a significant decrease in the concentration of surface nickel with heat treatment and changes in the surface nickel itself from a metallic to an oxide state. This correlates with the observed reduction in thrombogenicity. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 129–137, 2003
Micromechanical properties of demineralized dentin collagen with and without adhesive infiltration
Authors: Katz J. Lawrence , Spencer Paulette , Nomura Tsutomu , Wagh Ajay , Wang Yong 
Published: June 2003

AbstractIn a previous study, we reported the upper limit of Young's modulus of the unprotected protein at the dentin/adhesive interface to be 2 GPa. In this study, to obtain a more exact value of the moduli of the components at the d/a interface, we used demineralized dentin collagen with and without adhesive infiltration. The prepared samples were analyzed using micro‐Raman spectroscopy (μRS) and scanning acoustic microscopy (SAM). Using an Olympus UH3 SAM (Olympus Co., Tokyo), measurements were recorded with a 400 MHz burst mode lens (120° aperture angle; nominal lateral resolution, 2.5 μm). A series of calibration curves were prepared using the relationship between the ultrasonically measured elastic moduli of a set of known materials and their SAM response. Finally, both the bulk and bar wave elastic moduli were computed for a set of 13 materials, including polymers, ceramics, and metals. These provided the rationale for using extensional wave measurements of the elastic moduli as the basis for extrapolation of the 400 MHz SAM data to obtain Young's moduli for the samples: E = 1.76 ± 0.00 GPa for the collagen alone; E = 1.84 ± 0.65 GPa for the collagen infiltrated with adhesive; E = 3.4 ± 1.00 GPa for the adhesive infiltrate. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 120–128, 2003
Assembly and characterization of biofunctional neurotransmitter‐immobilized surfaces for interaction with postsynaptic membrane receptors
Authors: Saifuddin Uroosa , Vu Tania Q. , Rezac Miroslav , Qian Haohua , Pepperberg David R. , Desai Tejal A. 
Published: June 2003

AbstractHerein, we report progress toward the development of bioactive surfaces based on γ‐aminobutyric acid (GABA), a major neurotransmitter in the nervous system. Whereas immobilization techniques have focused largely on antibodies, enzymes, and receptors, to our knowledge, this is the first report of a prototype neurotransmitter‐immobilized surface. Biosurfaces were assembled onto either mica or glass using passive adsorption of avidin and subsequent attachment of a derivatized form of GABA via a biotin–avidin affinity bond. Surface characterization of these prepared bimolecular surfaces was determined using atomic force microscopy in tapping mode. The data reveal that passive adsorption of avidin is uniformly dispersed and cluster densities can be controlled through the concentration of the avidin incubation solution. GABA tethered via biotin to these avidin surfaces displayed a unique surface topology; in addition, histograms of surface heights suggest two different types of molecular cluster populations. Functional assays were performed to test the biological activity of the synthesized GABA. Anti‐GABA antibody directed to these bimolecular surfaces result in morphological topologies and histograms that indicate antibody–antigen binding. However, nonspecific anti‐immunoglobulin G antibodies directed to these surfaces show low binding affinity. Taken together, the data support the idea that the synthesized surfaces are biofunctional. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 184–191, 2003
In vitrofatigue behavior of human dentin with implications for life prediction
Authors: Nalla R. K. , Imbeni V. , Kinney J. H. , Staninec M. , Marshall S. J. , Ritchie R. O. 
Published: June 2003

AbstractAlthough human dentin is known to be susceptible to failure under repetitive cyclic fatigue loading, there are few reports in the literature that reliably quantify this phenomenon. This study seeks to address the paucity of fatigue data through a systematic investigation of the effects of prolonged cyclical loading on human dentin in an environment of ambient temperature Hank's balanced salt solution (HBSS) at cyclic frequencies of 2 and 20 Hz. The “stress‐life” (S/N) data thus obtained are discussed in the context of possible mechanisms of fatigue damage and failure in this material. In addition, stiffness loss data collectedin situduring theS/Ntests are used to deduce crack velocities and the thresholds for such cracking. These results are presented in a fracture mechanics context as plots of fatigue‐crack propagation rates (da/dN) as a function of the stress‐intensity range (ΔK). SuchS/Nandda/dN‐ΔKdata are discussed in light of the development of a framework for a fracture‐mechanics‐based methodology for the prediction of the fatigue life of teeth. It is concluded that the presence of small (on the order of 250 μm) incipient flaws in human teeth will not radically affect their useful life. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 10–20, 2003
Effect of alkaline treatment of pure titanium and its alloys on the bonding strength of dental veneering resins
Authors: Ban Seiji 
Published: June 2003

AbstractCommercially pure titanium (cpTi), Ti6Al4V, an experimental β‐type titanium (Ti 53.4 wt%, Nb 29 wt %, Ta 13 wt %, and Zr 4.6 wt %), and 12%AuPdAg alloy plates were sandblasted, cleaned in water, and dried. cpTi plates were treated with nine alkaline treatments that differed in the type of alkali, alkaline concentration, soaking temperature, soaking time, and heating temperature. cpTi plates that were only sandblasted or sandblasted and oxidized at 600°C for 1 h in air were also prepared. Finally, the bonding strengths of 11 kinds of surface‐treated cpTi to resin were measured using a pull‐shear bonding method after immersion in physiologic saline solution at 37°C for 24 h. The bonds of the standard alkaline‐treated cpTi and two titanium alloys to resins were 1.5–1.9 times stronger than those of sandblasted specimens (p < 0.01), but no significant effects of the alkaline treatment were observed on the 12% AuPdAg alloy. The greatest bonding strengths were found for cpTi treated with NaOH and KOH and then heated at 600°C (p < 0.01). In conclusion, alkaline treatment is a simple, effective surface modification of titanium that improves bonding to veneering resin. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 138–145, 2003
Vascular responsiveness to dimethylaminoethyl methacrylate and its degradation products
Authors: Abebe Worku , Maddux William F. , Schuster George S. , Lewis Jill B. 
Published: June 2003

AbstractThe increasing use of acrylate‐based resins in dentistry has raised questions about the biocompatibility of these substances with oral tissues. The focus of the present investigation was to assess the responsiveness of blood vessels to the resin polymerization accelerating agent dimethylaminoethyl methacrylate (DMAEMA) and its degradation products dimethylethanolamine (DME) and methacrylic acid (MAA), using the rat aortic ring preparation as a tissue model. DMAEMA induced concentration‐dependent relaxation of norepinephrine (NE)‐contracted aortic rings with and without endothelium. N‐nitro‐L‐arginine methyl ester (L‐NAME) selectively inhibited the endothelium‐dependent relaxation induced by DMAEMA, suggesting the release of nitric oxide from the endothelium by DMAEMA. Both indomethacin and glybenclamide attenuated the vasorelaxation elicited by DMAEMA in the presence as well as in the absence of endothelium, providing evidence for the role of vasorelaxant prostanoid(s) and KATP channel activation in the responses observed. On the other hand, while MAA was without any apparent effect on the rat aorta, DMAEMA at high and DME at relatively low concentrations caused contraction of the tissues with and without endothelium in the absence of NE. The DME‐induced contraction was inhibited by indomethacin, suggesting the involvement of contractile arachidonic acid metabolite(s) in the action of DME. This observation was supported by the findings of increased thromboxane A2 (TXA2) production in aortic rings incubated with DME. Taken together, the data suggest that both DMAEMA and its degradation product, DME, are vasoactive, inducing vasorelaxation and contraction by various mechanisms that may involve the release of nitric oxide from the endothelium, the activation of smooth muscle KATP channels, and the generation of vasorelaxant prostanoid(s) and TXA2. These effects may play a role in tissue homeostasis and certain adverse conditions associated with the use of dental resin materials containing DMAEMA and/or DME. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 155–161, 2003
Interactions between surface‐bound actin and complement, platelets, and neutrophils
Authors: Wetterö Jonas , Askendal Agneta , Tengvall Pentti , Bengtsson Torbjörn 
Published: June 2003

AbstractActin exists as globular (G) monomers or polymeric filaments (F) in the cytoplasm of eukaryotic cells, mediating cell morphologic changes and motility. Large amounts of this protein may be released out to the extracellular compartment during tissue injury, but little is known about its role in biomaterial‐related inflammation. We immobilized actin to methylated glass, methylated and aminated silicon, and gold model surfaces and studied the subsequent blood serum deposition and complement activation, generation of reactive oxygen species (ROS), and adhesion and aggregation of neutrophils and platelets. Null ellipsometry showed that approximately one monolayer of G‐actin can be immobilized onto the model surfaces and that actin in buffer polymerized on top of this by the addition of K+ and Mg2+ ions to form a thicker layer of firmly bound F‐actin. After serum incubation, F‐actin bound low amounts of anti‐complement factor 1q (anti‐C1q). Cell responses upon contact with actin‐coated surfaces were analyzed by luminol‐amplified chemiluminescence, lumi‐aggregometry, and fluorescence microscopy. It was shown that surface‐triggered aggregation, spreading, and generation of ROS are down‐regulated and comparable to the response by adsorbed albumin. However, F‐actin on gold surfaces recruited platelets in a C1q‐dependent manner. We conclude that in vitro adsorbed actin is a weak complement, platelet, and neutrophil activator, but that F‐actin associates with both C1q and platelets. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 162–175, 2003
Biological assessment of the bone–screw interface after insertion of uncoated and hydroxyapatite‐coated pedicular screws in the osteopenic sheep
Authors: Fini M. , Giavaresi G. , Greggi T. , Martini L. , Aldini N. Nicoli , Parisini P. , Giardino R. 
Published: June 2003

AbstractThe sheep seems to be a promising model of osteoporosis and biomaterial osteointegration in osteopenic bone. The long‐term ovariectomized sheep model was used for the biological investigation of bone healing around uncoated and hydroxyapatite (HA)‐coated pedicle screws in osteopenic bone. Four sheep were ovariectomized and four sheep were sham‐operated. Twenty‐four months after surgery, the animals were implanted with uncoated and HA‐coated stainless steel screws in the lumbar vertebral pedicles. Four months later, bone‐to‐implant contact, bone ingrowth, and bone hardness were measured around screws. Uncoated stainless steel presented significantly (p < 0.0005) lower bone‐to‐implant contact in healthy and osteopenic bone compared with HA‐coated stainless steel. HA significantly improved bone ingrowth in healthy bone (p < 0.05) compared with uncoated stainless steel. Osteopenia significantly (p < 0.05) reduced the area of bone ingrowth around the screw threads for both types of implants. In the inner thread area, bone microhardness significantly increased (p < 0.05) in HA‐coated surface versus uncoated for healthy and osteopenic bone. HA coating significantly enhances bone‐to‐implant contact also in osteopenic bone in comparison with uncoated stainless steel surfaces. Bone ingrowth and mineralization are ameliorated by the osteoconductive HA coating. However, osteopenia seems to greatly influence bone ingrowth processes around the implanted screws regardless of the characteristics of the material surface. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 176–183, 2003
The effects of degree of crosslinking on the fatigue crack initiation and propagation resistance of orthopedic‐grade polyethylene
Authors: Baker D. A. , Bellare A. , Pruitt L. 
Published: June 2003

AbstractCrosslinked ultrahigh molecular weight polyethylene (UHMWPE) has been recently approved by the Food and Drug Administration for use in orthopedic implants. The majority of commercially available UHMWPE orthopedic components are crosslinked using e‐beam or gamma radiation. The level of crosslinking is controlled with radiation dose and free radicals are eliminated through heat treatments to prevent long‐term degradation associated with chain scission or oxidation mechanisms. Laboratory studies have demonstrated a substantial improvement in the wear resistance of crosslinked UHMWPE. However, a concern about the resistance to fatigue damage remains in the clinical community, especially for tibial components that sustain high cyclic contact stresses. The objective of this study was to investigate both the initiation and propagation aspects of fatigue cracks in radiation crosslinked medical‐grade UHMWPE. This work evaluated three levels of radiation, which induced three crosslink densities, on the fatigue crack propagation and total fatigue life behavior. Both as‐received UHMWPE, as well as those that underwent an identical thermal history as the crosslinked UHMWPE were used as controls. Fractured crack propagation specimens were examined using scanning electron microscopy to elucidate fatigue fracture mechanisms. The results of this work indicated that a low crosslink density may optimize the fatigue resistance from both a crack initiation and propagation standpoint. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 146–154, 2003
XBRL: Don't lag behind the digital information revolution
Authors: Higgins Leslee N. , Harrell Horace W. 
Published: June 2003

AbstractDoes your company present information on the Internet? If you're not using XBRL—a special
standard for reporting financial information on the Internet—you could get left behind! Why not reap
the benefits of using this latest innovation? © 2003 Wiley Periodicals, Inc.
Is your audit committee watching IT risks?
Authors: Hadden Linda B. , Hermanson Dana R. 
Published: June 2003

AbstractRecent high‐profile accounting disasters have put audit committees on the hot seat. Some want audit
committees to lead the way in protecting against increased IT risks. But what is the committee's
role? And what do CEOs need to know about audit committee oversight of it? © 2003 Wiley
Periodicals, Inc.
PIMs: Is it time to give up your day planner?
Authors: Bean LuAnn , Barlow Judith , Hott David 
Published: June 2003

AbstractPersonal Information Managers (PIMs) have been around for awhile now. Maybe you are even ready to
give up your Day Planner and Post‐it Notes—and trust your computer or PDA to store all that vital
information. But can PIMs really do the job you need? Which one should you choose? Or are they
obsolete, as some critics suggest? The authors have some important insights and useful advice on getting
the most out of these often‐frustrating products. © 2003 Wiley Periodicals,
Inc.
Corporate governance: Big changes ahead
Authors: Goldberg Stephen R. , Danko Dori 
Published: June 2003

AbstractIs there life after Enron? The answer is obviously yes. But the business world—and corporate
governance—will never be the same. And what will this brave new world look like? The authors explain
what you need to know, and how to stay out of trouble. © 2003 Wiley Periodicals, Inc.
Investing in technology
Authors: Goldberg Stephen R. , Godwin Joseph H. 
Published: June 2003

AbstractKeen, Jack M. and Bonnie Digrius. 2003. Making Technology Investment Profitable, ROI Roadmap to
Better Business Cases (New York: John Wiley and Sons).Spencer, Robert H. and Randolph P. Johnston. 2003. Technology Best Practices (New York:
John Wiley and Sons).
Parameterization of charge model 3 for AM1, PM3, BLYP, and B3LYP
Authors: Thompson Jason D. , Cramer Christopher J. , Truhlar Donald G. 
Published: June 2003

AbstractWe have recently developed a new Class IV charge model for calculating partial atomic charges in molecules. The new model, called Charge Model 3 (CM3), was parameterized for calculations on molecules containing H, Li, C, N, O, F, Si, S, P, Cl, and Br by Hartree–Fock theory and by hybrid density functional theory (DFT) based on the modified Perdew–Wang density functional with several basis sets. In the present article we extend CM3 to semiempirical molecular orbital theory, in particular Austin Model 1 (AM1) and Parameterized Model 3 (PM3), and to the popular BLYP and B3LYP DFT and hybrid DFT methods, respectively. For the BLYP extension, we consider the 6‐31G(d) basis set, and for the B3LYP extension, we consider three basis sets: 6‐31G(d), 6‐31+G(d), and MIDI!6D. We begin with the previous CM3 strategy, which involves 34 parameters for 30 pairs of elements. We then refine the model to improve the charges in compounds that contain N and O. This modification, involving two new parameters, leads to improved dipole moments for amides, bifunctional H, C, N, O compounds, aldehydes, ketones, esters, and carboxylic acids; the improvement for compounds not containing N results from obtaining more physical parameters for carbonyl groups when the OCN conjugation of amides is addressed in the parameterization. In addition, for the PM3 method, we added an additional parameter to improve dipole moments of compounds that contain bonds between C and N. This additional parameter leads to improved accuracy in the dipole moments of aromatic nitrogen heterocycles with five‐membered rings. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1291–1304, 2003
On the kinematics of protein folding
Authors: Cahill Sean , Cahill Michael , Cahill Kevin 
Published: June 2003

AbstractWe offer simple solutions to three kinematic problems that occur in the folding of proteins. We show how to construct suitably local elementary Monte Carlo moves, how to close a loop, and how to fold a loop without breaking the bond that closes it. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1364–1370, 2003
New analytic approximation to the standard molecular volume definition and its application to generalized Born calculations
Authors: Lee Michael S. , Feig Michael , Salsbury Freddie R. , Brooks Charles L. 
Published: June 2003

AbstractIn a recent article (Lee, M. S.; Salsbury, F. R. Jr.; Brooks, C. L., III. J Chem Phys 2002, 116, 10606), we demonstrated that generalized Born (GB) theory provides a good approximation to Poisson electrostatic solvation energy calculations if one uses the same definitions of molecular volume for each. In this work, we present a new and improved analytic method for reproducing the Lee–Richards molecular volume, which is the most common volume definition for Poisson calculations. Overall, 1% errors are achieved for absolute solvation energies of a large set of proteins and relative solvation energies of protein conformations. We also introduce an accurate SASA approximation that uses the same machinery employed by our GB method and requires a small addition of computational cost. The combined methodology is shown to yield an efficient and accurate implicit solvent representation for simulations of biopolymers. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1348–1356, 2003
Implementation of the finite field perturbation method in the CRYSTAL program for calculating the dielectric constant of periodic systems
Authors: Darrigan Clovis , Rérat Michel , Mallia Giuseppe , Dovesi Roberto 
Published: June 2003

AbstractThe finite field approach has been implemented in the periodic ab initio CRYSTAL program and been used for calculating the dielectric constants of crystalline LiF and MgO (FCC structure) and BeO (wurtzite structure). To maintain the periodicity along the applied field direction, a “sawtooth” potential is used in conjunction with a supercell scheme. Supercells four to five times longer than the primitive cell in the direction of the applied field provide well‐converged results. The influence of the computational parameters is discussed. An alternative scheme has also been implemented, for inner check, that consists of applying a static electric field to a slab of increasing thickness in the direction orthogonal to the surface; the dielectric response at the center of the slab is shown to converge rapidly to the bulk value evaluated with the sawtooth field. The method is accurate and permits the determination of nonlinear corrections to the dielectric constant. When used in conjunction with the local density approximation (LDA) scheme, it provides for the dielectric constant of the three above‐mentioned compounds values close to those recently obtained with a time‐dependent density functional theory approach. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1305–1312, 2003