bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synergistic Effects ofD‐Glucosamine and Collagen Peptides on Healing Experimental Cartilage Injury
Authors: Hashida Masaki , Miyatake Katsuyuki , Okamoto Yoshiharu , Fujita Kotaro , Matumoto Takayuki , Morimatsu Fumiki , Sakamoto Koji , Minami Saburo 
Published: October 2003

AbstractWe investigated the synergistic wound‐healing effects ofD‐glucosamine (GlcN) and collagen peptide ($\overline M _{\rm w}$: 10 000 Daltons soluble collagen (S‐Co)) on injured cartilage. A injured cartilage model in rabbit was surgically created. Under general anesthesia, three holes at articular cartilage of the medial trochlear (one hole) and trochlear sulcus (two holes) of a distal femur were created using a high‐speed orthopedic drill. After surgery, rabbits were orally administered with collagen peptide (S‐Co group), GlcN (G group), or both (CoG group) for 2 or 3 weeks. In addition, glycine (Gly group) was administered as a control for the S‐Co group in three rabbits. Control rabbits were provided with water ad lib. After 2 weeks, the holes were filled by fibroblasts and chondroblasts in the treatment group, whereas in the control group, the holes were not filled completely unlike for the treatment group. Even three weeks later, only a small change was seen in the control group. In the group receiving collagen and GlcN, the holes were completely filled by proliferating chondroblasts, remodeling of bony trabeculae was also observed. Image analysis of Safranin O‐ and Alcian blue‐stained specimens showed increased production of proteoglycans and glycosaminoglycans, respectively, not only in the injured site, but also in the normal cartilage in the treated groups. The most enhanced healing of injury and increase in Safranin O and Alcian blue positive materials was observed in the CoG group. As a result, simultaneous administration of collagen and GlcN gave a fairly enhanced healing on restoration of cartilage injuries.Artificial cartilage injury at the stifle joint of a rabbit. a: proximal hole in trochlear sulcus; b: distal hole in trochlear sulcus; c: medial hole in medial trochlear ridge.magnified imageArtificial cartilage injury at the stifle joint of a rabbit. a: proximal hole in trochlear sulcus; b: distal hole in trochlear sulcus; c: medial hole in medial trochlear ridge.
Effects of Chitin/Chitosan and Their Oligomers/Monomers on Migrations of Macrophages
Authors: Okamoto Yoshiharu , Inoue Aika , Miyatake Katsuyuki , Ogihara Kikumi , Shigemasa Yoshihiro , Minami Saburo 
Published: October 2003

AbstractThe effects of chitin/chitosan and their oligomers/monomers on the migrations of mouse peritoneal macrophage (PEM) and the rat macrophage cell line (rMp) were evaluated in vitro. In direct migratory assay using the blind well chamber method, the migratory activity of PEM was enhanced significantly by chitin and chitosan oligomers (NACOS and COS, respectively), but reduced by chitin, chitosan, and the chitosan monomer (GlcN). The migratory activity of rMp was increased significantly by chitin, chitosan, and the polymers, NACOS and GlcN.
A Layer‐by‐Layer Film of Chitosan in a Taste Sensor Application
Authors: dos Santos David S. , Riul Antonio , Malmegrim Roger R. , Fonseca Fernando J. , Oliveira Osvaldo N. , Mattoso Luiz H. C. 
Published: October 2003

AbstractChitosan is alternated with sulfonated polystyrene (PSS) to build layer‐by‐layer (LBL) films that are used as sensing units in an electronic tongue. Using impedance spectroscopy as the principle method of detection, an array using chitosan/PSS LBL film and a bare gold electrode as the sensing units was capable of distinguishing the basic tastes – salty, sweet, bitter, and sour – to a concentration below the human threshold. The suitability of chitosan as a sensing material was confirmed by using this sensor to distinguish red wines according to their vintage, vineyard, and brands.PCA Plot for red wine samples obtained from impedance measurements at 1 kHz for the sensor array comprising a 3‐bilayer chitosan/PSS film and a bare gold electrode.magnified imagePCA Plot for red wine samples obtained from impedance measurements at 1 kHz for the sensor array comprising a 3‐bilayer chitosan/PSS film and a bare gold electrode.
Chemical Modification and some Aligned Composites of Chitosan in a Filament State
Authors: Hirano Shigehiro , Zhang Min , Yamane Hideki , Kimura Yoshiharu , Matsukawa Kojiro , Nakagawa Masuo 
Published: October 2003

AbstractThe mono‐filaments (> 10 m in length) of chitosan and the blends of chitosan‐collagen, chitin‐collagen and chitin‐silk fibroin were wet‐spun. The mono‐filaments were chemically N‐modified with each of n‐fatty acid anhydrides, intra‐molecular carboxylic anhydrides, fragrant aldehydes and transition metal ions. The mono‐filament was aligned on a straight line with the mono‐filament of silk fibroin or poly(ethylene terephthalate) (PET), and a bundle of one to three mono‐filaments was coated with a medium of sericin (Se), chitosan or N‐acylchitosan to give rise to novel silk‐mimic filament composites. The filaments coated with a medium of sericin exhibited 26–27 denier for the titer, 2.46–3.36 gf · denier−1 for the tenacity and 11.8–25.0% for the elongation. The apparent density (denier · μm−1 in the filament diameter) of the filament composites was about 3–4 times higher than that of the mono‐filaments. Portion of fragrant aldehydes in Schiff's base was slowly hydrolyzed at room temperature by contacting with atmospheric moisture in the open air, and released from the fragrant filaments and composites. The filament composites coated with a chitosan medium were thrombogenic, and those coated with N‐acylchitosans were antithrombogenic.An illustrated model for a silk‐mimic filament composite, N0(N2I‐FI).magnified imageAn illustrated model for a silk‐mimic filament composite, N0(N2I‐FI).
Water‐Soluble N‐(n‐Fatty acyl)chitosans
Authors: Hirano Shigehiro , Yamaguchi Yasuhiro , Kamiya Mitsutomo 
Published: October 2003

AbstractChitosan was partially N‐acylated by treatment with n‐fatty acid anhydrides in a homogeneous solution in 2 vol.‐% aqueous acetic acid‐methanol (1:2 v/v). The degree of substitution (d.s.) for N‐acyl groups in the water‐soluble N‐acylchitosan derivatives was in the range of 0.42–0.82 for N‐acetyl, 0.37–0.76 for N‐propionyl, 0.52–0.71 for N‐butyryl and 0.54–0.64 for N‐pentanoyl and ca. 0.58 for N‐hexanoyl, respectively.Water soluble N‐(n‐fatty acyl)chitosans.magnified imageWater soluble N‐(n‐fatty acyl)chitosans.
Metal dusting
Authors: Grabke H. J. 
Published: October 2003

AbstractThis introductory review paper summarizes shortly the research on metal dusting, conducted in the MPI for Iron Research during the last dozen years. Metal dusting is a disintegration of metals and alloys to a dust of graphite and metal particles, occurring in carburizing atmospheres at aC > 1 and caused by the tendency to graphite formation. The cause of destruction is inward growth of graphite planes into the metal phase, or in the case of iron and low alloy steels into cementite formed as an intermediate. The kinetics of metal dusting on iron and steels was elucidated concerning dependencies on time, temperature and partial pressures. High alloy steels and Ni‐base alloys are attacked through defects in the oxide scale which leads to pitting and outgrowth of coke protrusions, after initial internal formation of stable carbides M23C6, M7C3 and MC. A dense oxide layer prevents metal dusting, but formation of a protective Cr‐rich scale must be favored by a fine‐grain microstructure and/or surface deformation, providing fast diffusion paths for Cr. Additional protection is possible by sulfur from the atmosphere, since sulfur adsorbs on metal surfaces and suppresses carburization. Sulfur also interrupts the metal dusting mechanism on iron and steels, causing slow cementite growth. Under conditions where no sulfur addition is possible, the use of high Cr Nickelbase‐alloys is recommended, they are largely protected by an oxide scale and if metal dusting takes place, its rate is much slower than on steels.
Lanthanidocene Catalysts for the Homo‐ and Copolymerization of Ethylene with Butadiene
Authors: Boisson Christophe , Monteil Vincent , Ribour David , Spitz Roger , Barbotin Fanny 
Published: October 2003

AbstractAlkylation of lanthanidocene chloride complexes was performed with BuLi, Mg(Bu)(Oct), or an equimolar mixture of BuLi and AlH(iBu)2. In the case of the latter, chain transfer reactions were observed between neodymium and aluminium, and higher activities were obtained. The use of the silylene‐bridged complex, [Me2Si(3‐Me3SiC5H3)2]NdCl, in combination with BuLi and AlH(iBu)2 provided an efficient and unique catalyst for the copolymerization of ethylene with butadiene. Copolymers with high butadiene contents (up to 62 mol‐%) were synthesized. The microstructure of butadiene units was mostly trans‐1,4, and copolymers exhibited a strong alternating character. The influence of butadiene content on the thermal properties of the copolymers was also investigated.Copolymerization of ethylene with butadiene using 4/BuLi/AlH(iBu)2 (▪) and 2/BuLi/AlH(iBu)2 (▴).magnified imageCopolymerization of ethylene with butadiene using 4/BuLi/AlH(iBu)2 (▪) and 2/BuLi/AlH(iBu)2 (▴).
Photocrosslinking Polymerization of Methacrylate Modified Triethoxysilanes Polycondensates and Multifunctional Methacrylates
Authors: Pavlinec Juraj , Moszner Norbert 
Published: October 2003

AbstractDensely crosslinked polymer networks were prepared by fast, visible light‐induced polymerization at 20–22 °C. The two methacrylate functionalized triethoxysilanes polycondensates (MSiP) either alone, or in a mixture with methacrylate modified oxozirconium clusters, were polymerized separately and as comonomers to multimethacrylate monomers in a weight ratio of 1:0.9. Pure organic networks based on 1,6‐bis(2‐hydroxy‐3‐methacryloyloxyethoxycarbonylamino)‐2,2,4‐trimethylhexane (UDMA) were used for comparison in the same ratio to other comonomers. The networks based on organic bifunctional monomers showed high, around 85% conversion of double bonds. Nevertheless the non‐reacted monomer that migrates to the toluene amounts from 5.6 to 11.65 wt.‐%. Copolymerization of UDMA with tetrafunctional components resulted in networks with higher residual unsaturation up to 27.7%. This result points out the important role that functionality and the spacer structure between the monomer double bonds play in the extent of reaction. Based only on modified inorganic SiOSi nano‐structures the networks are characterized by nearly complete building up of MSiP in the network, extreme crosslinks density, and mostly less than 1 wt.‐% of soluble substances. However, residual unsaturations exceeded 22%. The advantage of copolymerization of MSiP with proper organic comonomers as potential solvent free matrices for dental composites was demonstrated by a network consisting of MSiP II and UDMA. The 13.7% of unreacted double bonds and 99.65 wt.‐% gel content approximated efforts to minimize residual unsaturation and maximize monomer conversion in cured networks.Monomers used for the synthesis of the densely crosslinked polymer.magnified imageMonomers used for the synthesis of the densely crosslinked polymer.
Simulation‐Assisted Evaluation of Acetylene Effect on Macromolecular Crosslinking Rate under Polyethylene Irradiation
Authors: Shyichuk Alexander , Tokaryk Galina 
Published: October 2003

AbstractGel content data on acetylene accelerated radiation crosslinking (R.A. Jones, J. Polym. Sci., Part B: Polym. Phys. 1994, 32, 2049) have been used to illustrate a new method to determine macromolecular crosslinking and scission yields. The sol‐gel analysis data have been plotted as log(sol) versus log(dose) resulting in quite linear plots having different slopes. The linear approximations with the least squares method resulted in gel‐points with a high accuracy. Computer simulations have shown the plot slope to be dependent on relative rate of competitive macromolecular scission. The scission/crosslink ratios have been found from the plot slopes using simulation software GelSim6. As a result acetylene gas has been found to be accelerating both crosslinking and scission rates: 60 times and 130 times, respectively. Obviously, the radiation yield of radicals is increased due to acetylene inhibiting the recombination of primarily induced radicals in a cage.Gel content vs. irradiation dose data plotted as log(sol) versus log(dose). Numbers near the curves indicate concentrations of acetylene gas (mmol · kg−1).magnified imageGel content vs. irradiation dose data plotted as log(sol) versus log(dose). Numbers near the curves indicate concentrations of acetylene gas (mmol · kg−1).
Prediction of Sol Fraction and Average Molecular Weights after Gelation for Non‐Linear Free Radical Polymerizations Using a Kinetic Approach
Authors: Costa Mário Rui P. F. N. , Dias Rolando C. S. 
Published: October 2003

AbstractMass balance equations in terms of the moment generating function of the distribution of mole concentrations of polymer species for free radical copolymerizations of mono/divinyl monomers could be numerically solved after gel point using open source code ACDC, needed for extremely stiff two‐point boundary value problems. For the first time, it became possible to compare the error of earlier well‐known approximated estimation methods for the weight fraction of sol and average molecular weights to this accurate mathematical solution. It turns out that predictions by the pseudo‐kinetic method are reasonable only when equal reactivity of double bonds prevails, causing early gelation in the batch reactor. Otherwise the discrepancies between the exact and approximate solutions are quite important.Comparison between predicted number‐average and weight‐average degrees of polymerization of sol in batch non‐linear free radical polymerizations of model system III.magnified imageComparison between predicted number‐average and weight‐average degrees of polymerization of sol in batch non‐linear free radical polymerizations of model system III.
Signatures of a Concentration‐Dependent Flory χ Parameter: Swelling and Collapse of Coils and Brushes
Authors: Baulin Vladimir A. , Halperin Avi 
Published: October 2003

AbstractThe quality of solvents of polymers is often described in terms of the Flory χ parameter typically assumed to depend only on the temperature, T. In certain polymer‐solvent systems fitting the experimental data enforces the replacement of (χT) by a concentration‐dependent χeff. In turn, this modifies the swelling and collapse behavior. These effects are studied, in the framework of a mean‐field theory, for isolated coils and for planar brushes. The ϕ dependence of χeff gives rise to three main consequences: (i) shift in the cross‐over between Gaussian and self‐avoidance regimes; (ii) a possibility of first‐order collapse transition for isolated flexible coils; (iii) the possibility of a first‐order phase transition leading to a vertical phase separation within the brush. The discussion relates these effects directly to thermodynamic measurements and does not involve a specific microscopic model. The implementation for the case of poly(N‐isopropylamide) (PNIPAM) brushes is discussed.ϕ vs. z plots, for brushes with N = 300, σ/a2 = 18 (σ/R = 0.019) characterized by different χeff.magnified imageϕ vs. z plots, for brushes with N = 300, σ/a2 = 18 (σ/R = 0.019) characterized by different χeff.
Reconstruction of the Chain Length Distribution for Vinyl‐Divinyl Copolymerization Using the Numerical Fractionation Technique
Authors: Papavasiliou Georgia , Teymour Fouad 
Published: October 2003

AbstractA proposed theory for evaluating the chain length distribution (CLD) using the numerical fractionation (NF) technique was extended to the vinyl‐divinyl (VDV) copolymerization. The CLD is reconstructed for this system, in which pendant double bond propagation leads to crosslinking and gel formation. The method was earlier developed for a non‐linear free‐radical polymerization scheme where chain transfer to polymer and termination by combination resulted in gel formation. The VDV study presented indicates that the proposed method of weighted summation (WS) accurately predicts the resulting CLDs evaluated using NF.Comparison of the overall polymer NF and the direct solution CLDs near the gel point.magnified imageComparison of the overall polymer NF and the direct solution CLDs near the gel point.
Dynamics of a Spreading Nanodroplet: A Molecular Dynamic Simulation
Authors: Yaneva Jacqueline , Milchev Andrey , Binder Kurt 
Published: October 2003

AbstractThe spreading of polymer nanodroplets upon a sudden change from partial to complete wetting on an ideally flat and structureless solid substrate has been studied by molecular dynamic simulations using a coarse‐grained bead‐spring model of flexible macromolecules. Tanner's law for the growth of the lateral droplet radius {R(t) ∝ t0.1} is found to hold as long as the droplet does not disintegrate into individually moving chains. The data for the contact angleθfollowing from Tanner's law correspond to a dependence on time {θ(t) ∝ t−0.3}. Our analysis of the mean square displacements of the polymer centers of mass reveals several dynamic regimes during the process of spreading. PACS numbers: 68.10.Gw, 05.70.Ln, 61.20.Ja, 8.45.Gd.Molecular dynamics results for the average mean square displacement of all polymer chains plotted vs. time for a broad range of values forεwall.magnified imageMolecular dynamics results for the average mean square displacement of all polymer chains plotted vs. time for a broad range of values forεwall.
Segmentation of Heteropolymer Sequences Specifying Subsequences with Different Composition and Statistical Properties
Authors: Gusev Leonid V. , Vasilevskaya Valentina V. , Makeev Vsevolod Ju. , Khalatur Pavel G. , Khokhlov Alexei R. 
Published: October 2003

AbstractWe have studied the segmentation of two‐letter AB heterosequences composed of subsequences with different composition and distribution of A and B monomer units along the chain. Our approach is based on the segmentation function S(k) introduced in the present work and on the Jensen–Shannon divergence measure determined with respect to the probabilities of the lengths of uniform blocks of A and B monomer units. It is shown that the function S(k) is extremely sensitive to the sequence statistics. Even visual analysis of S(k) allows judgment on some features of sequence statistics. In particular, function S(k) is constant for random copolymers, it is an oscillating function for random block copolymers and shows monotonic growth up to some constant value for proteinlike copolymers. However, due to significant fluctuations observed for short sequences, the function S(k) can be effectively used only for segmentation of a heterosequence composed of very long subsequences. On the other hand, we find that the Jensen–Shannon divergence measure does not allow one to judge the type of statistics, but is extremely efficient for segmentation of a heterosequence. Therefore, the two introduced functions, being mutually complementary, provide an effective approach for recognizing and segmentation of heterosequences. As an example, the methods developed are applied for concatenating sequences of different proteins.Segmentation function S(k, l, x) as a function of parameter k and starting number x of “window” for a sequence composed of elastin and ribonuclease sequences.magnified imageSegmentation function S(k, l, x) as a function of parameter k and starting number x of “window” for a sequence composed of elastin and ribonuclease sequences.
Computer Simulation of a Gold Nanoparticle Coated by Thiol‐Terminated Hydroquinonyl Oligoethers
Authors: Yin Kailiang , Xia Qing , Xu Duanjun , Xi Haitao , Sun Xiaoqiang , Chen Chenglung 
Published: October 2003

AbstractMolecular dynamics simulations were carried out to investigate the structure of a gold‐nanoparticle including 169 Au atoms coated by 42 thiol terminated hydroquinonyl oligoether chains. Three nanoparticle systems were constructed and investigated for structural comparison. The simulation showed that in all three nanosystems thiol‐chains self‐assembled on the surface of the gold cluster to form a stable gold nanoparticle. The configurations of the thiol chains and stacking of the phenylene rings were analyzed. The thiol‐chains are bundled into groups. Each group contains no more than four chains, in which phenylene rings in the thiol‐chains are correlated in parallel and perpendicular forms. Simple quantum mechanical calculations are carried out to elucidate the correlation of the phenylene rings.A snapshot of a TTOE‐Au nanoparticle.magnified imageA snapshot of a TTOE‐Au nanoparticle.
Evolution of Molecular Weight and Long Chain Branch Distributions in Olefin–Diene Copolymerization
Authors: Nele Márcio , Soares João B. P. , Pinto José Carlos 
Published: October 2003

AbstractA model for olefin–diene copolymerization and long chain branch formation was developed. The model shows that the number‐average molecular weight and branching density increases linearly with time in a semi‐batch polymerization, while the polydispersity depends on the diene content in the polymer and on the polymerization time. For low diene fractions or low polymerization times, the polydispersity increases linearly with time. For higher diene contents, the polydispersity increases exponentially with polymerization time after a critical polymer concentration is reached. The calculated distributions of branched species indicate that diene content influences the amount of highly branched chains produced in the polymerization, markedly broadening the distribution of molecular weight and leading to gel formation.Weight distribution of branched species after 30 min of polymerization.magnified imageWeight distribution of branched species after 30 min of polymerization.
New type of travelling wave solutions
Authors: Schneider K. R. , Shchepakina E. A. , Sobolev V. A. 
Published: October 2003

AbstractWe study the existence of combustion waves for an autocatalytic reaction in the non‐adiabatic case. Based on the fact that the reaction system has canard solutions separating the slow combustion regime from the explosive one, we prove by applying the geometric theory of singularly perturbed differential equations the existence of a new type of travelling waves solutions, the so‐called canard travelling waves. Copyright © 2003 John Wiley & Sons, Ltd.
The diffraction in a class of unbounded domains connected through a hole
Authors: Shestopalov Yu. V. , Smirnov Yu. G. 
Published: October 2003

AbstractIn this paper, the unique solvability, Fredholm property, and the principle of limiting absorption are proved for a boundary value problem for the system of Maxwell's equations in a semi‐infinite rectangular cylinder coupled with a layer by an aperture of arbitrary shape. Conditions at infinity are taken in the form of the Sveshnikov–Werner partial radiation conditions. The method of solution employs Green's functions of the partial domains and reduction to vector pseudodifferential equations considered in appropriate vectorial Sobolev spaces. Singularities of Green's functions are separated both in the domain and on its boundary. The smoothness of solutions is established. Copyright © 2003 John Wiley & Sons, Ltd.