bluuebunny/crossref_metadata_2025_split huggingface dataset:
PTC characteristics of (TiC/polyethylene) conductive composites in relation to their particle‐filled structures
Authors: Kataoka Mitsuhiro , Masuko Toru 
Published: May 2005

AbstractTitanium carbide (TiC)/polyethylene (PE) composites have been prepared with various volume fractions of TiC by a melt bleeding method. Two types of TiC powder with their different particle diameters, 1.48 µm (TiC‐A) and ca. 100 µm (TiC‐B), were utilized in the present study. The electric resistivities (ρ) of the samples decreased gradually with increasing TiC volume fraction (ϕA); in the case of smaller particle size, the value of ρ at room temperature jumped down in the relatively narrow range of ϕA = 0.39 to 0.42, reaching as low as 0.1 Ωcm. Temperature dependencies of ρ were also measured to examine the possible application of the composite to polymer PTC thermistors. The resistivity showed positive temperature dependence and changed abruptly in the tenth order of its magnitude during the melting transition of PE. The electric current cutoff characteristics of the samples indicated excellent features in the overcurrent response despite their low resistivity values, as compared with those of other PTC materials. In parallel, the mechanism of conductivity of the composite was discussed in terms of the percolation theory. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(2): 1–9, 2005; Published online in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/eej.20115
Systematic and anatomical studies of Inuleae and Plucheeae in Egypt
Authors: Zareh M. M. 
Published: May 2005

AbstractA systematic revision for the species of tribes Inuleae Cass. s.str. and Plucheeae (Benth.) Anderb. is provided. Four Plucheeae species belonging to four genera and 22 Inuleae species belonging to 11 genera are laggera viscosa comb. nova recognized. Leaf anatomy were studied. A key of the investigated species as well as SEM micrographs of leaf surface are provided. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tricalcium phosphate and glutaraldehyde crosslinked gelatin incorporating bone morphogenetic protein—A viable scaffold for bone tissue engineering
Authors: Yang Shu‐Hua , Hsu Chung‐King , Wang Kuo‐Cheng , Hou Sheng‐Mou , Lin Feng‐Huei 
Published: May 2005

AbstractBone defects caused by various etiologies must be filled with suitable substances to promote bone repair. Autogenous iliac crest graft is most frequently used, but is often associated with morbidities. Several bone graft substitutes have been developed to provide osteoconductive matrices as well as to enhance osteoinductivity. A tricalcium phosphate and glutaraldehyde crosslinked gelatin (GTG) scaffold, incorporated with bone morphogenetic proteins (BMPs), was developed to provide an alternative mean of bone tissue engineering. This study investigated differences between GTG and BMP‐4 immobilized GTG (GTG‐BMP) scaffolds on neonatal rat calvaria osteoblast activities. The GTG scaffold possessed an average pore size of 200 μm and a porosity of 75%. HE staining revealed uniform cell distribution throughout the scaffold 24 h post cell seeding. Alkaline phosphatase (ALP) activity of the GTG samples increased initially and then stabilized at 3 weeks postseeding. ALP activity of the GTG‐BMP samples was similar to that of the GTG samples in the second and third weeks, but it continued increasing and became significantly greater than that of the GTG samples by the fourth week. Gla‐type osteocalcin (Gla‐OC) activity of the GTG‐BMP samples was initially lower, but also became significantly greater than that of the GTG samples by the fourth week. An HE stain revealed greater numbers of attached cells and a richer matrix deposits in the GTG‐BMP samples. A von Kossa stain showed larger mineralizing nodules, in greater numbers, after 4 weeks of in vitro cultivation. These findings suggest that the GTG scaffold provides an excellent porous structure, conductive to greater cell attachment and osteoblast differentiation, and that utility can be significantly enhanced by the inclusion of BMPs. A GTG‐BMP scaffold holds promise as a superior bioactive material for bone tissue engineering. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Grafting reaction of poly(D,L)lactic acid with maleic anhydride and hexanediamine to introduce more reactive groups in its bulk
Authors: Pan Jun , Wang Yuanliang , Qin Suhua , Zhang Bingbing , Luo Yanfeng 
Published: May 2005

AbstractBioactivity of biomaterials was a new requirement, especially in tissue engineering and drug delivery. As a traditional used biomaterial, polylactide (PLA) had no bioactivity, of course, and it still had few reactive groups to introduce some bioactive molecules in its bulk. Here, we want to introduce carboxyl groups and amino groups in the side chain of PLA to get more reactive groups for incorporating bioactive molecular later and to maintain the structure of main chain to keep its biodegradability, and to settle the acidity of PLA during hydrolysis at the same time. It was performed as follows: first, maleic anhydride was covalently grafted onto the side chain of PLA by a free radical reaction at 100°C for 20 h with BPO as the initiator. Then, by amidation with a maleic anhydride group on PLA at room temperature, hexanediamine was incorporated. The resulting polymers have been characterized via GPC, 13C NMR, DSC, and TGA. The graft ratio was tested by titration. The pH changes during hydrolysis in 0.1 M PBS with pH 7.4 of PLA, MPLA, and HPLA were investigated. All the results showed that this research has grafted maleic anhydride and then hexanediamine in the bulk of PLA. The molecular weight degradation during reaction was less than 20%. The graft ratios of were 2.68, 2.36, and 1.86%, respectively in 5, 10, and 20% raw MA in MPLA; and the anhydride groups grafted in MPLA can completely react with hexanediamine at room temperature. The pH value of HPLA remained neutral within 12 weeks' hydrolysis compared with the resulted acidity of PLA and MPLA. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Collagen fiber orientation near dental implants in human bone: Do their organization reflect differences in loading?
Authors: Traini Tonino , Degidi Marco , Strocchi Rita , Caputi Sergio , Piattelli Adriano 
Published: May 2005

AbstractThis study is the first to investigate the collagen fiber orientation in human bone around titanium dental implants after loading. Birefringence under circularly polarized light (CPL) and scanning electron microscopy (SEM) investigation were used to assess both collagen orientation and density. Twenty osseointegrated dental implants were retrieved from the mandible bone of 10 patients and were used in the present study. The implants were retrieved after 6 months of function. The birefringence measurements were performed on digitized images using both the peri‐implant bone (PB) and the alveolar bone (AB) retrieved at the moment of implant placing. All images detected at 100× were measured using a software image analysis. The results showed that 32.96% (3.208 ± 0.435 mm2) of the PB area was composed of transverse collagen fibers while only 19.70% (1.957 ± 0.253 mm2) was composed of longitudinally collagen fibers. In the AB 26.99% (2.620 ± 0.520 mm2) of the examined area was composed of transverse collagen fibers while 22.25% (2.160 ± 0.320 mm2) was composed of longitudinally collagen fibers. The CPL measurements of the birefringence indicated that the difference in area between the two collagen fibers orientations was statistically significant (p = 0.03) for both AB and PB. In PB the transverse collagen fibers were significantly increased (p < 0.01) than in AB; also the longitudinal collagen fibers differ significantly in the two groups (p = 0.02). The transverse collagen fibers in PB are more present under the lower flank of the threads where the load acts with a compression vectors, while outside the tip of the implant threads the collagen fibers run more longitudinally due to the loads that act with a tensile vectors. SEM observations showed, in the first collagen layers facing the implant surface, a random direction of the collagen fibers, while in the areas away from the implant surface the collagen fibers were well oriented and run parallel. In conclusion, in these loaded dental implants, the bone adjacent to the first two implant threads shows a significant increase of the amount of transverse collagen fibers that were mainly associated with the lower flank of the threads where compressive load acts. The longitudinal collagen fibers also differs significantly from those found in the AB. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Elution study of unreacted Bis‐GMA, TEGDMA, UDMA, and Bis‐EMA from light‐cured dental resins and resin composites using HPLC
Authors: Sideridou Irini D. , Achilias Dimitris S. 
Published: May 2005

AbstractIn the present work the elution of residual monomers from light‐cured dental resins and resin composites into a 75% ethanol:water solution was studied using High‐Performance Liquid Chromatography (HPLC). The resins studied were made by light‐curing of bisphenol A glycol dimethacrylate (Bis‐GMA), triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), ethoxylated bisphenol A glycol dimethacrylate [Bis‐EMA(4)] and mixtures of these monomers. The resin composites were made from two commercial light‐cured restorative materials (Z100 MP and Filtek Z250), the resin matrix of which is based on copolymers of these monomers. The effect of the curing time on the amount of monomers eluted was investigated. The concentration of the extractable monomers was determined at several immersion periods from 3 h to 30 days. For all the materials studied, it was observed that the chemical structure of the monomers used for the preparation of the resins, which defines the chemical and physical structure of the corresponding resin, directly affects the amount of eluted monomers, as well as the time needed for the elution of this amount. In the case of composites, it seems that the elution process it is not influenced by the presence of filler. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
No effect of a type I collagen gel coating in uncemented implant fixation
Authors: Svehla M. , Morberg P. , Bruce W. , Walsh W.R. 
Published: May 2005

AbstractUncemented joint replacement with a variety of substrate materials, structures, and coatings are commonplace in arthroplasty. Even with specialized surgical preparation of bone, intimate contact between the implant and host bone may not always be achieved. This study evaluated the in vivo effect of fibrillar atelopeptide and PEG crosslinked collagens coatings placed directly into porous sintered bead structures on bone ingrowth using a skeletally mature bicortical, bilateral ovine tibia model. Bone ingrowth into the implants increased with time, although differences were not significant. At 4 weeks woven bone was present within the pores that remodeled with time. Significantly lower levels of ingrowth were observed in the intramedullary region of the implants when compared with the cortical region. Implant metal type did not affect ingrowth in both regions analyzed. Both fibrillar and crosslinked forms of dermal type I collagen did not significantly alter bone ingrowth. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Incorporating hidden Markov models for identifying protein kinase‐specific phosphorylation sites
Authors: Huang Hsien‐Da , Lee Tzong‐Yi , Tzeng Shih‐Wei , Wu Li‐Cheng , Horng Jorng‐Tzong , Tsou Ann‐Ping , Huang Kuan‐Tsae 
Published: May 2005

AbstractProtein phosphorylation, which is an important mechanism in posttranslational modification, affects essential cellular processes such as metabolism, cell signaling, differentiation, and membrane transportation. Proteins are phosphorylated by a variety of protein kinases. In this investigation, we develop a novel tool to computationally predict catalytic kinase‐specific phosphorylation sites. The known phosphorylation sites from public domain data sources are categorized by their annotated protein kinases. Based on the concepts of profile Hidden Markov Models (HMM), computational models are trained from the kinase‐specific groups of phosphorylation sites. After evaluating the trained models, we select the model with highest accuracy in each kinase‐specific group and provide a Web‐based prediction tool for identifying protein phosphorylation sites. The main contribution here is that we have developed a kinase‐specific phosphorylation site prediction tool with both high sensitivity and specificity. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1032–1041, 2005
Gene products with evolutionary functions
Authors: Arber Werner 
Published: May 2005

AbstractIt is often tacitly assumed that all gene products serve the needs of life functions of the individual carrying the genome. However, a close look at the formation of genetic variations, which are the drivers of biological evolution, reveals a different view. While a majority of the products of genes, such as housekeeping genes and genes essential for each individual, when exposed to particular life conditions respond to the definition given above, other gene products clearly carry out evolutionary functions at the level of populations. Products of these evolution genes act as generators of genetic variations and/or as modulators of the frequency of genetic variation. This is most readily seen with bacterial populations. Many different mechanisms contribute to the occasional, overall formation of genetic variations. These mechanisms can be grouped into three mechanistically and qualitatively different strategies of generating genetic variations. In addition to the activities of evolution genes, specific properties of matter such as tautomery also contribute to the formation of genetic variations. The views that nature cares actively for biological evolution are documented by evidence taken mainly from microbial genetics. Essential elements of the theory of molecular evolution are discussed, as well as the relevance of this theory for higher organisms and its impact on our worldview.
Structural analysis of a highly acetylated protein using a curved‐field reflectron mass spectrometer
Authors: Wang Dongxia , Thompson Paul , Cole Philip A. , Cotter Robert J. 
Published: May 2005

AbstractMatrix‐assisted laser desorption/ionization mass spectrometry and tandem mass spectrometry (MS/MS) were used to determine the multiple acetylation sites in the histone acetyltransferase (HAT): p300‐HAT. Partial cleavage of the peptides containing acetylated lysine residues by trypsin provided a set of nested sequences that enabled us to determine that multiple acetylation occurs on the same molecule. At the same time, cleavages resulting in a terminal unacetylated lysine suggested that not all of these sites are fully modified. Using MS and MS/MS, we were able to characterize both the unmodified and acetylated tryptic peptides covering more than 82% of the protein.
Two‐stage affinity purification for inducibly phosphorylated membrane proteins
Authors: Peirce Matthew J. , Begum Shajna , Saklatvala Jeremy , Cope Andrew P. , Wait Robin 
Published: May 2005

AbstractCharacterisation of tyrosine phosphorylations induced in immune cells in response to inflammatory stimuli may help elucidate the molecular bases of the diversity of immune responses. We have used anti‐phosphotyrosine antibodies in combination with cell surface biotinylation in a two‐step affinity purification procedure to recover pervanadate‐induced tyrosine phosphorylated proteins from sub‐cellular compartments, including the cell surface, of murine T cells and macrophages prior to separation by solution‐phase isoelectric focussing and one‐dimensional gel electrophoresis and identification by tandem mass spectrometry.
Quantitative analysis of protein expression using amine‐specific isobaric tags in Escherichia coli cells expressing rhsA elements
Authors: Aggarwal Kunal , Choe Leila H. , Lee Kelvin H. 
Published: May 2005

AbstractWe describe the use of amine‐specific isobaric tags for protein expression quantification to study the effect of rhsA element over‐expression in Escherichia coli. The use of an isobaric tagging strategy facilitates a shotgun approach to proteomic analysis and enables quantitation of up to four samples in parallel, based on the reporter ion series using tandem mass spectrometry (MS/MS). Using a liquid chromatography matrix‐assisted laser desorption/ionization approach, 23 139 MS/MS spectra were collected. Five thousand sixty‐three peptides derived from 780 proteins were quantified including several lower abundance proteins, such as transcription factors, DnaB and DnaG. More than 65% of the proteins had at least two high confidence peptide matches per protein (p < 0.05). Further, a statistical test based on the Grubb's and Rosner's tests was able to discriminate outlier data. The removal of outlier data had no significant effect on the functional categories of proteins that were represented in the study.
Improvements in two‐dimensional gel electrophoresis by utilizing a low cost “in‐house” neutral pH sodium dodecyl sulfate‐polyacrylamide gel electrophoresis system
Authors: Graham David R. M. , Garnham Christopher P. , Fu Qin , Robbins Jeffrey , Van Eyk Jennifer E. 
Published: May 2005

AbstractTwo‐dimensional gel electrophoresis (2‐DE) is widely used for initial protein separation in proteomics. Commercial products using neutral pH sodium dodecyl sulfate‐polyacrylamide gel electrophoresis ((SDS‐PAGE)/(Bis (2‐hydroxyethyl) imino‐tris (hydroxymethyl) methane‐HCl, or Bis‐Tris)) have greatly improved this technique, but cost and limited sizes restrict their applications. An “in‐house” system is presented, resulting in better resolution, separation, and new spot visualization and improved resolution when compared to Tris‐HCl gels. Their utility is demonstrated using albumin‐depleted serum samples, rabbit heart left ventricle, and human immunodeficiency virus type 1 (HIV‐1).
Acrylamide‐agarose copolymers: Improved resolution of high molecular mass proteins in two‐dimensional gel electrophoresis
Authors: Roncada Paola , Cretich Marina , Fortin Riccardo , Agosti Susanna , De Franceschi Lucia , Greppi Gian Franco , Turrini Francesco , Carta Franco , Turri Stefano , Levi Marinella , Chiari Marcella 
Published: May 2005

AbstractA method was developed in order to analyse high molecular mass proteins by two‐dimensional (2‐D) electrophoresis using a copolymer of acrylamide and allyl agarose instead of Bis cross‐linked polyacrylamide (PA) gels in sodium dodecyl sulphate‐electrophoresis. In this work, the matrix composition was optimised to improve the resolution of proteins larger than 200 kDa. The new gel type does not entrap large proteins and protein complexes at the application site. Mechanical properties were investigated through rheological measurements, which suggested the formation of a highly entangled elastomeric soft gel. A high 2‐D resolution of proteins, extracted from membranes of red blood cells, was obtained in these gels. An example of tryptic digestion, peptide extraction and matrix‐assisted laser desorption/ionisation‐time of flight mass spectrometry was reported. The results demonstrate that the new gel is fully compatible with mass spectrometry protein analysis.
A quantitative proteomic approach using two‐dimensional gel electrophoresis and isotope‐coded affinity tag labeling for studying human 20S proteasome heterogeneity
Authors: Froment Carine , Uttenweiler‐Joseph Sandrine , Bousquet‐Dubouch Marie‐Pierre , Matondo Mariette , Borges Jean‐Philippe , Esmenjaud Charlotte , Lacroix Christelle , Monsarrat Bernard , Burlet‐Schiltz Odile 
Published: May 2005

AbstractMammalian proteasomes are macromolecular complexes formed of a catalytic 20S core associated to two regulatory complexes. The 20S core complex consists of four stacked rings of seven α or β subunits. Three β subunits contain a catalytic site and can be replaced by three interferon γ‐inducible counterparts to form the immunoproteasome. Cells may constitutively possess a mixture of both 20S proteasome types leading to a heterogeneous proteasome population. Purified rat 20S proteasome has been separated in several chromatographic fractions indicating an even higher degree of complexity in 20S proteasome subunit composition. This complexity may arise from the presence of subunit isoforms, as previously detected in purified human erythrocyte 20S proteasome. In this study, we have used a quantitative proteomic approach based on two‐dimensional gel electrophoresis and isotope‐coded affinity tag (ICAT™) labeling to quantify the variations in subunit composition, including subunit isoforms, of 20S proteasomes purified from different cells. The protocol has been adapted to the analysis of low quantities of 20S proteasome complexes. The strategy has then been validated using standard proteins and has been applied to the comparison of 20S proteasomes from erythrocytes and U937 cancer cells. The results obtained show that this approach represents a valuable tool for the study of 20S proteasome heterogeneity.
Novel polystyrene‐supported zirconocene catalyst for olefin polymerization and its catalytic kinetics
Authors: Wang Wenqin , Wang Li , Wang Jianfeng , Wang Jianjun , Ma Zhenli 
Published: May 2005

AbstractThrough the Diels–Alder reaction between cyclopentadiene groups attached to polystyrene in the presence of zirconocene, novel polystyrene‐supported metallocene catalysts were prepared. A novel method for immobilizing metallocene catalysts was investigated, and the resultant polystyrene‐supported metallocene for olefin polymerization was studied. The results of olefin polymerization showed that different crosslinking degrees of support in the catalyst system had significant effects on the catalytic behavior. The influence of the [Al]/[Zr] molar ratio and the temperature on the (co)polymerization activity was studied. When 1‐hexene and 1‐dodecene were used for copolymerization with ethylene, an obvious positive comonomer effect was observed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2650–2656, 2005
Novel catalyst system of MCl2/FeCl3·6H2O/PPh3 (M = Ni, Co, or Mn) for the atom transfer radical polymerization of methyl methacrylate
Authors: Jian Cao , Chen Jin , Zhang Keda 
Published: May 2005

AbstractMCl2 (M = Ni, Co, Sn, or Mn) and PPh3 together acted as a catalyst for the radical polymerization of methyl methacrylate (MMA) in the presence of ethyl 2‐bromoisobutyrate as an initiator. The four systems all led to conventional radical polymerizations, which yielded polymers with a weight‐average molecular weight/number‐average molecular weight (Mw/Mn) ratio greater than 2.0 and became well controlled when a certain amount of FeCl3·6H2O was added. The polymerizations of MMA catalyzed by these four FeCl3‐modified catalyst systems provided well‐defined polymers with low polydispersities (Mw/Mn < 1.28). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2625–2631, 2005