bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural Characteristics and Permeability of Ethyl Cellulose Films Containing Different Plasticizers
Authors: Fekete Rita , Marosi György , Fekete Pál , Dredán Judit , Marton Sylvia , Antal István 
Published: June 2006

AbstractThe effect of different type of plasticizers was investigated in ethyl cellulose as coating polymer for manufacturing coated pellets of modified release containing a water soluble model drug. Scanning electron microscopic image analysis (SEM), differential scanning calorimetry (DSC), X‐ray photoelectron spectroscopic chemical surface analysis (XPS) were used to study the films, and the dissolution profiles of coated pellets were evaluated. The effect of the different plasticizers and coating levels on the first order dissolution rate constant is determined by statistical experimental design. Correlation was found between the dissolution rate constant and the structural characteristics of the coating layer containing different plasticizers. Partial segregation of the plasticizers was detected especially on the surface of the films, which is in correlation with the differences in the glass transition temperatures. PEG 400 is found to be compatible enough to form continuous, durable EC coating at 5% concentration level, which gave the slowest dissolution.
Drug Release Study of Systems Containing the Tragacanth and Collagen Composite: Release Characterization and Viscoelastic Measurements
Authors: Kaffashi B. , Zandieh A. , Khadiv‐Parsi P. 
Published: June 2006

AbstractThe kinetics of water penetration and pentoxifilline release from both Tragacanth gum and Tragacanth/Collagen matrices has been examined in pure deionised water. The rheological oscillatory measurements of their gel layer obtained by swelling of the imprinted pentoxifilline‐filled polymer matrix with water have been performed. To qualify a polymer for application in drug formulation, appropriate gel stiffness is required. The aqueous solution of Tragacanth does not seem to acquire the actual strength that a hydrogel must retain for this purpose. Thus, along with Tragacanth, gelatin, CaCl2 and 1, 8 octandiamine curing agent were individually blended in a mixture with Tragacanth gum to improve the gel behavior and drug delivery of the system. The strength of the gel at the body temperature (37 °C) was studied using a cone and plate rheometer. It was found that gelatin could enhance the gel strength of Tragacanth by forming a porous composite. The drug release to an aqueous solution at room temperature was analyzed to be slower for a composite of 1:2 Tragacanth/Collagen.
A Novel Transparent Polyacetylene Bearing a Triphenylamine Moiety Prepared with a [Rh(norbornadiene)Cl]2 Catalyst
Authors: Miyasaka Atsushi , Nakamura Minoru , Mawatari Yasuteru , Orito Kazuhiko , Tabata Masayoshi 
Published: June 2006

AbstractNovel soluble polyacetylenes having a triphenylamine moiety were synthesized by a [Rh(norbornadiene)Cl]2 catalyst under quite mild conditions in fairly high yields. The obtained polymer showed to have trans‐transoid sequence as the major main‐chain structure which was generated through the so‐called cis‐to‐trans isomerization was already induced even during the polymerization. The HCl doping of the polymer was resulted in the formation of the oxidized polymer where the so‐called polaron or bipolaron was produced. In addition, we found that in the case of the pristine polymer unpaired electrons mainly localized on the triphenylamine moiety as the side chain. On the other hand, after the doping the unpaired electron delocalized on the main chain of the polymer.
Comparative Study on the Collapse Transition of Poly(N‐isopropylacrylamide) Gels and Magnetic Nanoparticles Loaded Poly(N‐isopropylacrylamide) Gels
Authors: Filipcsei Genovéva , Szilágyi András , Csetneki Ildikó , Zrínyi Miklós 
Published: June 2006

AbstractA novel polymer gel exhibiting simultaneous temperature and magnetic field sensitivity has been prepared and studied. Poly(N‐isopropylacrylamide) (PNIPA) and magnetic nanoparticles (magnetite, Fe3O4) loaded PNIPA gel beads with mm size and monolith gels with cm size were prepared. The dependence of swelling degree on the temperature has been studied. The effects of cross‐linking density and the presence of magnetic nanoparticles on the equilibrium swelling degree as well as on the collapse transition have been investigated. Swelling kinetic measurements were also made. By comparing the equilibrium swelling properties of PNIPA and magnetite loaded PNIPA gels it was found that the built in magnetic nanoparticles do not modify the temperature sensitivity of these gels. Within the experimental accuracy the temperature of the collapse transition was not sensitive to the presence of magnetic particles. We have compared the swelling behaviour of mm size gel beads to the cm size monolith gels in order to study the influence of surface skin layer on the swelling equilibrium. It was established that the extent of surface skin formation was decreased by the presence of magnetic particles.
Statistical Modeling of Unidirectional Fibrous Structures
Authors: Vas László M. 
Published: June 2006

AbstractSome textiles such as slivers, rovings, yarns, and highly oriented polymer fibers as well as the reinforcing structure of unidirectional composites have a kind of unidirectional or quasi‐unidirectional fibrous structures. The statistical properties of their structure and strength can be modeled by using idealized fiber bundles as model elements. In this study the tensile test process of unidirectional short fiber structures is modeled for different damage types using the instantaneous fracture model and special idealized fiber bundles for gradual damages such as fiber breakage and fiber slippage. Constant fiber length and exponential fiber length distribution as extreme cases of the Erlang distributions were used for analysis. In case of exponential fiber length distribution and constant fiber breaking strain simple analytical relationships between the mean tensile strength and the fiber length were derived and compared to those for constant fiber length and written in a general form which is valid for all the damage modes discussed. The convex linear combination of the solutions for exponential fiber length distribution and constant fiber length was proposed to use for cases when the variation coefficient of the fiber length is between 0 and 1. The practical applicability of the results was demonstrated by identifying the relationship between the mean tensile strength and the average molecule mass of polypropylene fibers that made it possible to estimate the critical molecule mass and the tensile strength of the molecules without further measurements.
Curing and Physical Properties of Natural Rubber/Wood Flour Composites
Authors: Ichazo Miren Nekane , Hernández Marianela , Albano Carmen , González Jeanette 
Published: June 2006

AbstractNatural rubber based composites were prepared by incorporating Wood flour of two different particle size ranges (250–300 µm) and (300–425 µm) and concentrations (15 and 30 phr) into the matrix, using a Banbury® internal mixer according to a base formulation. Curing characteristics of the samples were studied. Influence of particle size and loading of filler on the properties of the composites was analyzed. Results obtained show that the addition of wood flour to natural rubber increased scorch time and curing time and caused improvement in modulus at 300% strain and in tear properties. However, it decreased tensile strength and elongation at break. The particle size range of 300–425 µm was found to offer the best overall balance of mechanical and dynamic properties (tan δ and viscous torque). Swelling behavior of the composites in toluene was also analyzed in order to determine the rubber volume fraction and crosslinking density. Composites with the bigger particle size wood flour were found to have greater crosslinking density than the ones with smaller particle size, fact that could possibly indicate a better rubber‐filler interaction in the former. Major percentage of filler increased slightly this interaction. Water absorption behavior of the composites with wood flour reached a maximum of 12% w/w when 30 phr of filler were incorporated; nonetheless, particle size did not affect this property. The ageing study in presence of air at 70 °C revealed that natural rubber composites with wood flour maintained the same classification cell with temperature as the pure rubber. A compound with 30 phr of carbon black was prepared for comparative purposes. Results obtained were as expected. Scorch time decreased and higher values of modulus at 300% strain and tensile strength were achieved, due to strongest interaction between filler and elastomer.
Development of Hemp Fibre – PP Nonwoven Composites
Authors: Hargitai Hajnalka , Rácz Ilona , Anandjiwala Rajesh 
Published: June 2006

AbstractSummary:
Nonwoven mats from hemp and polypropylene fibres in various proportions were produced and hot pressed to make composite material. The effect of hemp fibre content and anisotropy in nonwoven mats resulting from the carding technology were examined on the basis of the three‐point bending, tensile and impact properties of the resultant composite materials. Because of the hydrophilic nature and poor dimensional stability of cellulosic fibres due to swelling, the effect of water sorption on mechanical performances was also investigated. Optimal mechanical properties were achieved in composites made from 40–50% of hemp fibre by weight. As it was expected, better mechanical properties were found in the specimens cut from the composite sheets parallel to the direction of carding. A strong decrease in three point bending properties was noticed after immersing the composite samples in distilled water for 19 days, while the impact strength increased. Double carding of raw materials resulted in a decreased anisotropy in composite material.
Physical Properties of the Biodegradable Polymer Compositions Containing Natural Polyesters and their Synthetic Analogues
Authors: Dacko Piotr , Kowalczuk Marek , Janeczek Henryk , Sobota Michal 
Published: June 2006

AbstractThe thermal, mechanical and thermo‐mechanical properties of polymer compositions, containing synthetic biodegradable polymers i.e. polylacide (PLA) and aliphatic‐aromatic copolyester (BTA), natural biopolyester n‐PHB and its synthetic atactic analog (a‐PHB) were investigated. Thermal properties of the polymer compositions were studied by means of DSC . The compositions of various polymer weight ratio were tested. Compositions containing BTA and n‐PHB create polyphase systems, what was confirmed by DSC. In this case the two Tg and two Tm values were observed. Polymer compositions containing PLA and BTA showed different behaviours. At the BTA content up to 30 weight % only one Tg and one Tm were indicated. At the increase of the BTA content to 50% weight and above, the two Tg, and two Tm were observed. Mixtures of BTA with n‐PHB, PLA and with a‐PHB show considerably greater values of the strain (ε) in comparison with initial polymers (n‐PHB, PLA). It was found that in contrary to mixtures containing PLA, at the BTA content in the mixture with n‐PHB above 50% of weights increases not only the strain, but also the stress at break (σ). Strong increase of the ε value in PLA/a‐PHB mixtures with the content of a‐PHB above 30% of weights were observed.
Absorbency Behaviour of Vertically Positioned Nonwoven Glass Fiber Mats in Case of Two Different Resin Viscosities
Authors: Gombos Zoltán , Nagy Veronika , Koštáková Eva , Vas László Mihály 
Published: June 2006

AbstractThe resin absorbency of vertically positioned chopped strand mat samples was examined as a function of time with a microtensiometer type Krüss K12. With the help of a theoretical model the results of this measurement can be interpreted and evaluated. The samples of different structure (mats bonded with powder or emulsion) were compared and the impact of resin viscosity was studied and conclusions were drawn about the pore and capillary sizes in the mats. The results verified the applicability of the method and revealed the typical pore characteristics of mats and this way estimations can be made on the properties of composites.
Construction of Pre‐Deformed Shapes for Rapid Tooling in Injection Molding
Authors: Kovács József Gábor 
Published: June 2006

AbstractThe major issues in the development of injection molding technology include the progress in CAE and the developments in tool design methodology such as rapid tooling. The applicability of rapid tooling in injection molding was examined using unbalanced cooling to analyze the warpage and shrinkage. Moldflow Plastics Insight simulation software was used for the deformation calculations with different mold thermal conductivities. It can be concluded that the decreasing mold thermal conductivity will dramatically increase the volumetric shrinkage and the warpage as well. Because of these effects, it is of fundamental importance to compensate for the shrinkage and warpage, so in the paper a new design methodology is suggested for rapid tooling, which is based on the pre‐deformed model.
Aromatic Polyamides Containing Pendent Acetoxybenzamide Groups
Authors: Sava Ion , Bruma Maria 
Published: June 2006

AbstractPolycondensation reaction of 5‐(4‐acetoxy‐benzamide) isophthaloylchloride with different aromatic diamines gave a series of polyisophthalamides with good solubility in organic solvents. These polymers showed good thermal stability with initial decomposition temperature above 300 °C and glass transition temperature in the range of 220–335 °C. Thin, flexible, transparent films were cast from solutions, having good electroinsulating properties.
Interaction of Maleic Acid Copolymers with Collagen
Authors: Anghelescu‐Dogaru Adina Graziella , Chitanu Gabrielle Charlotte , Tenhu Heikki 
Published: June 2006

AbstractOne of the present trends to increase the efficiency of the chrome tanning process is the use of chemicals which change the affinity and induce a better binding of the chromium ions in the hides. Recently, some anionic polyelectrolytes based on poly(acrylic acid) or maleic acid copolymers were developed as additives in the chrome tanning. The effect of polyelectrolytes could be explained by their interaction with the collagen from hide. In our work four maleic acid copolymer/collagen systems were investigated by turbidimetric, conductometric and potentiometric titrations. The interaction between the two macromolecular compounds was clearly evidenced, and its dependence on the chemical structure of the maleic acid copolymer and on the amount of added chromium ions was studied. Homogeneous systems or turbid dispersions were observed depending on the hydrophilic or hydrophobic character of the maleic copolymer, on the [CH]/[MP] ratio, and on the concentration of the chromium ions.
Structural Changes in Drawn Poly(L‐lactide)/Clay Hybrid Films
Authors: Ninomiya Naoya , Fujimori Atsuhiro , Masuko Toru 
Published: June 2006

AbstractThe films composed of poly(L‐lactide)(PLLA)/organoclay hybrids (PLACHs) have been prepared via a melt‐compounding process, in which the organoclay paticles are uniformly dispersed in the PLLA matrix. The changes in PLLA crystal orientation for the uniaxially drawn films were studied by differential scanning calorimetry, X‐ray diffractometry and transmission electron microscopy. Additionally, temperature dependence of the mechanical properties for these drawn films were examined by a dynamic viscoelastometer. After drawing the quenched PLACHs film at 90 °C, the orientation and crystallinity of PLLA crystal increased rapidly with increasing drawing ratio (λ) in the range more than 3 times. At the higher λ, the organoclay platelet particles in the PLACHs became parallel to the draw direction. The mechanical properties of drawn PLACHs were strongly dependent on both clay concentration and λ.
Entries in the Leiden Duchenne muscular dystrophy mutation database: An overview of mutation types and paradoxical cases that confirm the reading‐frame rule
Authors: Aartsma‐Rus Annemieke , Van Deutekom Judith C. T. , Fokkema Ivo F. , Van Ommen Gert‐Jan B. , Den Dunnen Johan T. 
Published: June 2006

AbstractThe severe Duchenne and milder Becker muscular dystrophy are both caused by mutations in the DMD gene. This gene codes for dystrophin, a protein important for maintaining the stability of muscle‐fiber membranes. In 1988, Monaco and colleagues postulated an explanation for the phenotypic difference between Duchenne and Becker patients in the reading‐frame rule: In Duchenne patients, mutations induce a shift in the reading frame leading to prematurely truncated, dysfunctional dystrophins. In Becker patients, in‐frame mutations allow the synthesis of internally deleted, but largely functional dystrophins. Currently, over 4700 mutations have been reported in the Leiden DMD mutation database, of which 91% are in agreement with this rule. In this study we provide an update of the mutational variability in the DMD gene, particularly focusing on genotype–phenotype correlations and mutations that appear to be exceptions to the reading‐frame rule. Muscle Nerve, 2006
Stretch‐induced force deficits in murine extensor digitorum longus muscles after cardiotoxin injection
Authors: Markert Chad , Petroski Gregory F. , Childers Charles K. , McDonald Kerry S. , Childers Martin K. 
Published: June 2006

AbstractA leftward shift in a muscle's length–tension relationship is thought to impair myofilament overlap. We hypothesized that left‐shifted muscles would incur greater eccentric contraction–induced damage compared to controls. We evaluated contractile properties and force deficits in regenerating murine extensor digitorum longus (EDL) muscles 7, 14, and 21 days after cardiotoxin (CTX) injection. Specific tension recovered to control values by 21 days. CTX‐injected muscles demonstrated left‐shifted length–tension curves and incurred greater contraction‐induced force deficits than controls (P < 0.001) on day 7. We speculate that increased contraction‐induced damage in 7‐day CTX‐injected muscles results from changes in myofilament overlap that occurs during early regeneration. Muscle Nerve, 2006
CAV3 gene mutation analysis in patients with idiopathic hyper‐CK‐emia
Authors: Reijneveld Jaap C. , Ginjaar Ieke B. , Frankhuizen Wendy S. , Notermans Nicolette C. 
Published: June 2006

AbstractAs caveolin‐3 deficiencies may explain persistent hyper‐CK‐emia, we performed CAV3 gene mutation analysis and immunohistochemistry for caveolin‐3 in 31 patients with idiopathic hyper‐CK‐emia. In 2 of 29 patients who donated blood, variants in the CAV3 gene were detected. Although immunohistochemical analysis strongly suggested that caveolin‐3 was properly localized in the muscle tissue of the two affected patients, it may not function normally and could thus explain their persistent hyper‐CK‐emia. Our findings contribute to the clarification of unexplained persistent hyper‐CK‐emia, but further research is needed before CAV3 gene mutation analysis becomes part of the routine evaluation of these patients. Muscle Nerve, 2006
Structural properties of network revenue management models: An economic perspective
Authors: Morton Alec 
Published: June 2006

AbstractMany revenue management problems have a network aspect. In this paper, we argue that a network can be thought of as a system of substitutable and complementary products, and the value of a revenue management model should be supermodular or submodular in the availability of two resources as the resources are economic substitutes or complements. We demonstrate that this is true in the case of a two‐resource dynamic stochastic revenue management model and show how this applies for multi‐resource deterministic static revenue management models. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006
Autonomic self‐organization architecture for wireless sensor communications
Authors: Chen Jiann‐Liang , Lu Hsi‐Feng , Lee Chien‐An 
Published: June 2006

AbstractWireless sensor nodes may be spread over large areas and long distances, and require multi‐hop communications between nodes, making direct management numerous wireless sensor nodes inefficient. Hierarchical management can be adopted to control several nodes. Effectively controlling the top‐level nodes can decrease the costs of managing nodes and of the communication among them. The lower‐level nodes are controlled and organized with the higher‐level nodes. This study presents an algorithm for self‐organization mechanism of higher‐level nodes, contesting member nodes by multi‐hop to form hierarchical clusters, and applying the ‘20/80 rule’ to determine the ratio of headers to member nodes. Furthermore, the broadcast tree is constructed with the minimum number of hops. Simulation results indicate that the mechanism has a 6–22% lower cover loss than other approaches. The average delay of the minimum hop count approach is 0.22–1.57ms less than that of free hop count approach. The simulation also reveals the influence of 20/80 rule on cluster formation between sensor nodes. Copyright © 2006 John Wiley & Sons, Ltd.
Safety of medications prescribed before and during early pregnancy in a cohort of 81 975 mothers from the UK General Practice Research Database
Authors: Hardy Janet R. , Leaderer Brian P. , Holford Theodore R. , Hall Gillian C. , Bracken Michael B. 
Published: June 2006

AbstractPurposeTo demonstrate a linkage methodology for mother and baby automated medical records, and describe frequency, type, and pregnancy risk level of medications prescribed during pregnancy in a GPRD cohort, 1991–1999.MethodsWe linked records using a two‐stage algorithm and selected pairs with ≥7 months prenatal records and ≥2 records in baby's first year of life. Periods of interest were: 90 days prior to a woman's earliest identified pregnancy record (Period I), and this record plus 70 days (Period II, approximate early pregnancy). Medications were classified using the British National Formulary and US Food and Drug Administration Pregnancy Risk Categories.ResultsWe achieved over 80% record linkage and defined a cohort of 81 975. Sixty‐five per cent of mothers had ≥1 prescription during both periods combined. Most frequent medications in Period I were anti‐bacterial, contraceptive, topical steroid, and bronchodilator. In Period II, they were folic acid, anti‐bacterial, antacid, and gynecological anti‐infective. In Period I, 4% were FDA category A (considered safest), 34% B, and 49% C and D combined. By Period II, prescription of category A medications increased (folic acid, iron) while other categories declined. Category X medications, with potential teratogenic risk that outweighs maternal benefit, were prescribed to 5714 (7%) women in Period I, and 501 (0.6%) women in Period II (46% progesterone).ConclusionsOne in every 164 women received a category X prescription in early pregnancy. The visit when pregnancy is first medically recognized represents an opportunity to review prescribed medications in light of contraindication and/or fetal risk. Copyright © 2006 John Wiley & Sons, Ltd.