bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characteristics of atmospheric stability above an evergreen forest in central Cambodia
Authors: Tamai Koji , Nobuhiro Tatsuhiko , Shimizu Akira , Kabeya Naoki , Chann Sophal , Nang Keth 
Published: February 2008

AbstractMicrometeorological observations from a tower in a forest in central Cambodia were used to estimate forest water yields. For these estimates, the turbulent boundary layer was identified from tower observations of wind profiles. Indices including the stability length, friction velocity, and Richardson numbers were calculated to diagnose boundary layer characteristics. The calculated stability length indicated that the atmospheric condition was between weakly unstable and weakly stable 63% of the time. The calculated friction velocity exceeded 0·5 m s−1 77% of the time, and the calculated Richardson number was smaller than the critical number (0·2) 72% of the time. The indices calculated in this study indicate that the degree of atmospheric stability over this evergreen forest in central Cambodia is generally suitable for tower flux observations. Copyright © 2008 John Wiley & Sons, Ltd.
Investigation of runoff generation in a pristine, poorly gauged catchment in the Chilean Andes II: Qualitative and quantitative use of tracers at three spatial scales
Authors: Blume Theresa , Zehe Erwin , Bronstert Axel 
Published: February 2008

AbstractUnderstanding runoff generation processes is important for flood prediction, water management, erosion control, water quality, contaminant transport and the evaluation of impacts of land use change. However, little process research has been carried out in southern Chile. In particular the young volcanic ash soils, which are typical for this area, are not well understood in their hydrologic behaviour. To establish a ‘reference study’ which can then be used for comparison with other (disturbed) sites, this study focuses on the investigation of runoff generation processes in an undisturbed, forested catchment in the Chilean Andes. The paper reports on an investigation of these processes with different tracer methods at different spatial scales. Hydrograph separation with environmental isotopes and geochemical constituents was used on the catchment scale. Thermal energy was used as a tracer to investigate groundwater–surface water interactions at the local stream reach scale and dye tracers were used to study infiltration and percolation characteristics at the plot scale. It was found that pre‐event water dominates the storm hydrograph. In the lower reaches, however, water usually exfiltrates from the stream into the adjacent aquifer. The dye tracer experiments showed that while preferential vertical flow dominates under forest, water infiltrates as a straight horizontal front in the bare volcanic ashes (no vegetation) on the catchment rim. Subsurface flow patterns in the forest differ significantly from summer to winter. All three approaches used in this study suggest an important shift in dominant processes from dry to wet season. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of passivation treatments on titanium alloy with nanometric scale roughness and induced changes in fibroblast initial adhesion evaluated by a cytodetacher
Authors: Wang C.‐C. , Hsu Y.C. , Su F.C. , Lu S.C. , Lee T.M. 
Published: February 2008

AbstractPassivation treatments of titanium alloy alter not only its nanosurface characteristics of oxides and ion release but also surface roughness (Ra), and wettability as well, where nanosurface characteristics of oxides include chemistries of oxides, amphoteric‐OH groups adsorbed on oxides, and oxide thickness. Consequently, the passivation treatment affects the alloy's cyto‐comparability. In this study, we polish specimens to achieve nanometric scale roughness. In addition, treatment effects are evaluated for surface topology, roughness, wettability, and responses of fibroblasts consisting of MTT assay, initial adhesion strength, and morphology. The initial adhesion strength is measured using a cyto‐detacher that achieves nano‐Newton resolution. Results reveal that (1) the treatment effects on the percentage of TiOH basic groups and wettability are nearly collinear; (2) the Ra of passivated Ti‐6Al‐4V ranges from 1.9 to 7.4 nm; (3) the initial adhesion strength of fibroblast ranges from 58 to 143 nN, and it is negatively correlated to the Ra; (4) the passivation results in distinguishable morphologies, which further substantiate the negative correlation between cell initial adhesion force and Ra; and (5) our results fall short of confirming previous reports that found positively charged functional groups promoting fibroblast attachment and spread. Potential causes of the inconsistency are addressed. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Microarray‐based gene expression analysis of human osteoblasts in response to different biomaterials
Authors: Bombonato‐Prado Karina F. , Bellesini Larissa S. , Junta Cristina M. , Marques Márcia M. , Passos Geraldo A. , Rosa Adalberto L. 
Published: February 2008

AbstractSeveral biomaterials have been widely used in bone regeneration/substitution procedures in orthopedic and oral surgery. However, how these biomaterials alter osteoblast gene expression is poorly understood. We therefore attempted to address this question by using cDNA microarray technique to identify genes that are differentially regulated in osteoblasts exposed to biomaterials comprehending the biocompatibility spectrum of bioactive (bioglass and hydroxyapatite), bioinert (Ti and stainless steel), and biotolerant (polymethylmethacrylate). By using a cDNA microarray containing 687 human IMAGE sequences, we identified in primary cultures of osteoblastic cells differentiated from the human bone marrow and exposed to these biomaterials, genes whose expression was significantly upregulated or downregulated. Among the differentially expressed genes we have found those involved with cell cycle regulation, cell differentiation and proliferation, apoptosis, cell adhesion, bone mineralization and skeletal development. These results can be relevant to a better understanding of the molecular mechanism underlying the behavior of osteoblasts in bone regenerative procedures. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Poly(ethylene terephthalate)/hydroxyapatite biomaterials: Preparation, characterization, and in vitro bioactivity
Authors: Siriphannon Punnama , Monvisade Pathavuth 
Published: February 2008

AbstractPoly(ethylene terephthalate)/hydroxyapatite (PET/HAp) composites were prepared by mixing HAp powder with a mixture solution of cyclic oligo(ethylene terephthalate) (C‐OET) and dibutyl tinoxide catalyst in dichrolomethane, and then shaping the precomposites in cylindrical pellets. The C‐OET in the precomposites was ring‐opening polymerized (ROP) to PET under vacuum at 250°C for 24 h. The PET/HAp composites were formulated with HAp to PET ratios of 60:40 (H6P4) and 50:50 (H5P5). The ROP‐PET in the composites was present as a thin‐layer coating on the HAp grains and evenly distributed throughout the samples. Compressive strength of the PET/HAp composites was significantly increased from 8 MPa of the H10P0 to 17 and 29 MPa for H6P4 and H5P5, respectively. In vitro bioactivity of the PET/HAp composites was studied by soaking in simulated body fluid (SBF) at 36.5°C for 7–28 days. After prolonged soaking, the HAp nanocrystals precipitated from the SBF solution and formed as a layer of globular aggregates, coated on the composite surfaces. The H6P4 composite showed faster formation rate of nano‐HAp than the H5P5 composite, indicating that the bioactivity of PET/HAp composites depended on the amount of HAp. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Decreased macrophage density on carbon nanotube patterns on polycarbonate urethane
Authors: Kim Jong Youl , Khang Dongwoo , Lee Jong Eun , Webster Thomas J. 
Published: February 2008

AbstractNanotechnology is creating materials that can regenerate numerous tissues (including those used for bone, vascular, cartilage, bladder, and neuronal systems) better than what is currently being implanted. Despite this promise, little is known about the functions of wound healing cells (such as macrophages) on nanomaterials. Carbon nanotubes are intriguing nanomaterials for implantation due to their unique biologically inspired surface, electrical, and mechanical properties. For the above reasons, the objective of the present study was to investigate macrophage function on one promising type of nano‐implant material for orthopedic applications (carbon nanotubes microscopically aligned on polymers). To align carbon nanotubes on polymers, a novel imprinting method placing carbon nanotubes in grids of defined spacings (from 30 to 100 μm) on a polymer matrix was developed. In this study, the selective adhesion and proliferation of macrophages after 4 h, 24 h, and 4 days on aligned regions of a currently implanted polymer (specifically, polycarbonate urethane) compared to aligned carbon nanotube patterns were found. That is, decreased macrophage functions were observed in this study on aligned regions of carbon nanotubes compared to polycarbonate urethane. The present in vitro study, thus, provided evidence of the ability of carbon nanotubes to down‐regulate macrophage adhesion and proliferation which is important to decrease a harmful persistence wound‐healing reaction to orthopedic implants. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Novel hydroxyapatite/carboxymethylchitosan composite scaffolds prepared through an innovative “autocatalytic” electroless coprecipitation route
Authors: Oliveira J. M. , Costa S. A. , Leonor I. B. , Malafaya P. B. , Mano J. F. , Reis R. L. 
Published: February 2008

AbstractA developmental composite scaffold for bone tissue engineering applications composed of hydroxyapatite (HA) and carboxymethylchitosan (CMC) was obtained using a coprecipitation method, which is based on the “autocatalytic” electroless deposition route. The results revealed that the pores of the scaffold were regular, interconnected, and possess a size in the range of 20–500 μm. Furthermore, the Fourier transform infra‐red spectrum of the composite scaffolds exhibited all the characteristic peaks of apatite, and the appearance of typical bands from CMC, thus showing that coprecipitation of both organic and inorganic phases was effective. The X‐ray diffraction pattern of composite scaffolds demonstrated that calcium‐phosphates consisted of crystalline HA. From microcomputed tomography analysis, it was possible to determine that composite scaffolds possess a 58.9% ± 6% of porosity. The 2D morphometric analysis demonstrated that on average the scaffolds consisted of 24% HA and 76% CMC. The mechanical properties were assessed using compressive tests, both in dry and wet states. Additionally, in vitro tests were carried out to evaluate the water‐uptake capability, weight loss, and bioactive behavior of the composite scaffolds. The novel hydroxyapatite/carboxymethylchitosan composite scaffolds showed promise whenever degradability and bioactivity are simultaneously desired, as in the case of bone tissue‐engineering scaffolding applications. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Design and characterization of a novel chitosan/nanocrystalline calcium phosphate composite scaffold for bone regeneration
Authors: Chesnutt Betsy M. , Viano Ann M. , Yuan Youling , Yang Yunzhi , Guda Teja , Appleford Mark R. , Ong Joo L. , Haggard Warren O. , Bumgardner Joel D. 
Published: February 2008

AbstractTo meet the challenge of regenerating bone lost to disease or trauma, biodegradable scaffolds are being investigated as a way to regenerate bone without the need for an auto‐ or allograft. Here, we have developed a novel microsphere‐based chitosan/nanocrystalline calcium phosphate (CaP) composite scaffold and investigated its potential compared to plain chitosan scaffolds to be used as a bone graft substitute. Composite and chitosan scaffolds were prepared by fusing microspheres of 500–900 μm in diameter, and porosity, degradation, compressive strength, and cell growth were examined. Both scaffolds had porosities of 33–35% and pore sizes between 100 and 800 μm. However, composite scaffolds were much rougher and, as a result, had 20 times more surface area/unit mass than chitosan scaffolds. The compressive modulus of hydrated composite scaffolds was significantly higher than chitosan scaffolds (9.29 ± 0.8 MPa vs. 3.26 ± 2.5 MPa), and composite scaffolds were tougher and more flexible than what has been reported for other chitosan‐CaP composites or CaP scaffolds alone. Using X‐ray diffraction, scaffolds were shown to contain partially crystalline hydroxyapatite with a crystallinity of 16.7% ± 6.8% and crystallite size of 128 ± 55 nm. Fibronection adsorption was increased on composite scaffolds, and cell attachment was higher on composite scaffolds after 30 min, although attachment rates were similar after 1 h. Osteoblast proliferation (based on dsDNA measurements) was significantly increased after 1 week of culture. These studies have demonstrated that composite scaffolds have mechanical properties and porosity sufficient to support ingrowth of new bone tissue, and cell attachment and proliferation data indicate composite scaffolds are promising for bone regeneration. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Preparation and properties of porous microspheres made from borate glass
Authors: Conzone Samuel D. , Day Delbert E. 
Published: February 2008

AbstractDysprosium lithium‐borate glass microspheres and particles, ranging from 45 to 150 μm in diameter, were reacted with a 0.25M phosphate solution at 37°C, whose pH was either 3 or 8.8. The glass reacted nonuniformly and was converted into a porous, amorphous, hydrated, dysprosium phosphate reaction product. The amorphous product had the same volume and shape (pseudomorphic) as the unreacted glass, and could be dried without cracking. After heating at 300°C for 1 h, the amorphous reaction product had a specific surface area of ≈200 m2/g, a pore size of ≈30 nm, and nominal crushing strength of ≈10 MPa. When the reaction product was heated to 600°C for 15 min, the specific surface area decreased to ≈90 m2/g and the nominal crushing strength increased to 35 MPa. Heating above 615°C converted the amorphous dysprosium phosphate product into crystalline DyPO4, which contained open porosity until heated above 800°C for 15 min. Highly porous materials of different chemical composition can be prepared by chemically reacting a borate‐based glass with an aqueous solution at low‐temperature (<100°C). These highly porous materials are easy to process, and are considered candidates for controlled drug delivery, catalysis, chromatographic separation, filtration, and as bioactive materials. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Adsorbed serum albumin is permissive to macrophage attachment to perfluorocarbon polymer surfaces in culture
Authors: Godek M. L. , Michel R. , Chamberlain L. M. , Castner D. G. , Grainger D. W. 
Published: February 2008

AbstractMonocyte/macrophage adhesion to biomaterials, correlated with foreign body response, occurs through protein‐mediated surface interactions. Albumin‐selective perfluorocarbon (FC) biomaterials are generally poorly cell‐conducive because of insufficient receptor‐mediated surface interactions, but macrophages bind to albumin‐coated substrates and also preferentially to highly hydrophobic fluorinated surfaces. Bone marrow macrophages (BMMO) and IC‐21, RAW 264.7, and J774A.1 monocyte/macrophage cells were cultured on FC surfaces. Protein deposition onto two distinct FC surfaces from complex and single‐component solutions was tracked using fluorescence and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) methods. Cell adhesion and growth on protein pretreated substrates were compared by light microscopy. Flow cytometry and integrin‐directed antibody receptor blocking were used to assess integrins critical for monocyte/macrophage adhesion in vitro. Albumin predominantly adsorbs onto both FC surfaces from 10% serum. In cultures preadsorbed with albumin or serum‐dilutions, BMMO responded similar to IC‐21 at early time points. Compared with Teflon® AF, plasma‐polymerized FC was less permissive to extended cell proliferation. The β2 integrins play major roles in macrophage adhesion to FC surfaces: antibody blocking significantly disrupted cell adhesion. Albumin‐mediated cell adhesion mechanisms to FC surfaces could not be clarified. Primary BMMO and secondary IC‐21 macrophages behave similarly on FC surfaces, regardless of preadsorbed protein biasing, with respect to adhesion, cell morphology, motility, and proliferation. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Enhanced smooth muscle cell adhesion and proliferation on protein‐modified polycaprolactone‐based copolymers
Authors: Bramfeldt Hanna , Vermette Patrick 
Published: February 2008

AbstractSmooth muscle cells (SMC) were cultured for up to 6 days on copolymer films fabricated from a PCL‐PEG‐PCL block copolymer or P(ε‐CL‐co‐D,L‐LA)‐PEG‐P(ε‐CL‐co‐D,L‐LA), named P(100/0) and P(70/30), respectively. The films were modified by aminolysis using 1,6‐hexanediamine, and fibronectin, fibrinogen, or fibrin layers were subsequently immobilized by physisorption or by covalent coupling using imidoester chemistry. Immobilization of all the tested proteins resulted in significantly enhanced cell adhesion on these polymers. Moreover, we found that covalently immobilized proteins supported significantly greater cell proliferation than physisorbed proteins over 6 days. SMC cultured on P(100/0) films modified by covalently attached fibronectin or fibrin layers proliferated at a rate comparable to that observed on control tissue culture polystyrene. The proposed surface modification schemes were much less efficient in improving cell attachment and proliferation on P(70/30) films. However, prewetting P(70/30) with a phosphate buffer prior to aminolysis significantly improved cell numbers following immobilization of fibronectin. Immunostaining of smooth muscle‐specific α‐actin of SMC grown on protein‐modified P(100/0) 8 h and 48 h after cell seeding, confirmed preserved SMC phenotype on all modified surfaces. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
In vitro investigation of maleated poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) for its biocompatibility to mouse fibroblast L929 and human microvascular endothelial cells
Authors: Li Xiao‐Tao , Sun Jie , Chen Song , Chen Guo‐Qiang 
Published: February 2008

AbstractPoly (3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx), a polyester with strong mechanical properties and biocompatibility, is a member of microbial polyhydroxyalkanoates (PHA) family. Maleic anhydride was used to graft PHBHHx to form maleated PHBHHx (Ma‐PHBHHx). Ma‐PHBHHx with a graft degree of 0.59% was found to be more thermo‐stable in comparison with PHBHHx. In vitro study demonstrated that the biocompatibility to mouse fibroblast L929 and human microvascular endothelial cells (HMEC) was improved in different degrees on Ma‐PHBHHx films and scaffolds. Compared with their growth on PHBHHx, L929 and HMEC grown on Ma‐PHBHHx films and scaffolds showed ∼120% and 260% more in proliferation rates, respectively. Morphology study suggested that fine whorl‐like surface structures with porosities on Ma‐PHBHHx films attributed to MA grafting would be better for cell attachment and proliferation. Ma‐PHBHHx scaffolds prepared by thermally induced phase separation (TIPS) with increased porosity, hydrophilicity, surface energy, and charges also were more favorable for cell growth. In addition, Ma‐PHBHHx showed an accelerated degradation incubation in SBF at 37°C, losing 21.4% of its original weight after 21 weeks while PHBHHx just lost 7.3%. Based on the improved biocompatibility, reasonable mechanical properties as well as accelerated biodegradation, Ma‐PHBHHx has shown advantages over PHBHHx as a biomaterial for biomedical applications. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Electrocoating of stainless steel coronary stents for extended release of paclitaxel
Authors: Okner R. , Oron M. , Tal N. , Nyska A. , Kumar N. , Mandler D. , Domb A. J. 
Published: February 2008

AbstractNonbiodegradable polymer coating based on N‐(2‐carboxyethyl)pyrrole (PPA) and butyl ester of PPA (BuOPy) were successfully electrodeposited on a stainless steel stent surface using cyclic voltammetry. Chemical composition of the coating was examined by X‐ray photoelectron spectroscopy. Polymer stability was examined by immersing the coated stent into 1:1 solution of fetal calf serum:seline solution up to 1 year and implantation subcutaneously in mouse for 1 week. Morphology changes were then recorded by scanning electron microscopy. Paclitaxel loading was carried out by immersion into drug solution and its release was detected by HPLC. The results show that thin (single micrometers), uniform coating with various morphology and hydrophobicity can be created by electrochemical deposition. The polymer did not show significant histopathological or morphological changes in vitro and in vivo. The surface properties allow loading appropriate amounts of paclitaxel and release it slowly up to a month. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Increased chondrocyte adhesion on nanotubular anodized titanium
Authors: Burns Kevin , Yao Chang , Webster Thomas J. 
Published: February 2008

AbstractPrevious studies have demonstrated increased osteoblast (bone‐forming cells) functions (including adhesion, synthesis of intracellular collagen, alkaline phosphatase activity, and deposition of calcium‐containing minerals) on titanium anodized to possess nanometer features compared with their unanodized counterparts. Such titanium materials were anodized to possess novel nanotubes also capable of drug delivery. Since titanium has not only experienced wide spread commercial use in orthopedic but also in cartilage applications, the objective of the present in vitro study was for the first time to investigate chondrocyte (cartilage synthesizing cells) functions on titanium anodized to possess nanotubes. For this purpose, titanium was anodized in dilute hydrofluoric acid at 20 V for 20 min. Results showed increased chondrocyte adhesion on anodized titanium with nanotube structures compared with unanodized titanium. Importantly, the present study also provided evidence why. Since material characterization studies revealed significantly greater nanometer roughness and similar chemistry as well as crystallinity between nanotubular anodized and unanodized titanium, the results of the present study highlight the importance of the nanometer roughness provided by anodized nanotubes on titanium for enhancing chondrocyte adhesion. In this manner, the results of the present in vitro study indicated that anodization might be a promising quick and inexpensive method to modify the surface of titanium‐based implants to induce better chondrocyte adhesion for cartilage applications. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009