bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of glycosaminoglycan depletion on the friction and deformation of articular cartilage
Authors: Katta J , Stapleton T , Ingham E , Jin Z M , Fisher J 
Published: March 2008

Glycosaminoglycans (GAGs) have been shown to be responsible for the interstitial fluid pressurization of articular cartilage and hence its compressive stiffness and load-bearing properties. Contradictory evidence has been presented in the literature on the effect of depleting GAGs on the friction properties of articular cartilage. The aim of this study was to investigate the effect of depleting GAGs on the friction and deformation characteristics of articular cartilage under different tribological conditions. A pin-on-plate machine was utilized to measure the coefficient of friction of native and chondroitinase ABC (CaseABC)-treated articular cartilage under two different models: static (4 mm/s start-up velocity) and dynamic (4 mm/s sliding velocity; 4 mm stroke length) under a load of 25 N (0.4 MPa contact stress) and with phosphate-buffered saline as the lubricant. Indentation tests were carried out at 1 N and 2 N loads (0.14 MPa and 0.28 MPa contact stress levels) to study the deformation characteristics of both native and GAG-depleted cartilage samples. CaseABC treatment rendered the cartilage tissue soft owing to the loss of compressive stiff-ness and a sulphated-sugar assay confirmed the loss of GAGs from the cartilage samples. CaseABC treatment significantly increased (by more than 50 per cent) the friction levels in the dynamic model ( p < 0.05) at higher loading times owing to the loss of biphasic lubrication. CaseABC treatment had no effect on friction in the static model in which the cartilage surfaces did not have an opportunity to recover fluid because of static loading unlike the cartilage tissue in the dynamic model, in which translation of the cartilage surfaces was involved, ensuring effective biphasic lubrication. Therefore the depletion of GAGs had a smaller effect on the coefficient of friction for the static model. Indentation tests showed that GAG-depleted cartilage samples had a lower elastic modulus and higher permeability than native tissue. These results corroborate the role of GAGs in the compressive and friction properties of articular cartilage and emphasize the need for developing strategies to control GAG loss from diseased articular cartilage tissue.
OR PRACTICE—The Dance of the Thirty-Ton Trucks: Dispatching and Scheduling in a Dynamic Environment
Authors: Durbin Martin , Hoffman Karla 
Published: March 2008

We report on the application of operations research to a very complex scheduling and dispatching problem. Scheduling and dispatching are never easy, but the scheduling of concrete deliveries is particularly difficult for several reasons: (1) concrete is an extremely perishable product—it can solidify in the truck if offloading is delayed by a few hours; (2) customer orders are extremely unpredictable and volatile—orders are often canceled or drastically changed at the last minute; (3) the concrete company overbooks by as much as 20% to compensate for customer unpredictability; (4) many orders require synchronized deliveries by multiple trucks; (5) when a truck arrives at a customer site, the customer may not be ready for the delivery, or a storm may negate the ability to use the concrete; and (6) most of the travel takes place in highly congested urban areas, making travel times highly variable. To assist the dispatchers, schedulers, and order takers at this company, we designed and implemented a decision-support tool consisting of both planning and execution tools. The modules determine whether new orders should be accepted, when drivers should arrive for work, the real-time assignment of drivers to delivery loads, the dispatching of these drivers to customers and back to plants, and the scheduling of the truck loadings at the plants. For the real-time dispatching and order-taking decisions, optimization models are solved to within 1% of optimality every five minutes throughout the day. This nearly continuous reoptimization of the entire system allows quick reactions to changes. The modeling foundation is a time-space network with integer side constraints. We describe each of the models and explain how we handle imperfect data. We also detail how we overcome a variety of implementation issues. The success of this project can be measured, most importantly, by the fact that the tool is being ported by the parent company, Florida Rock, to each of its other ready-mix concrete companies. Second, the corporation is sufficiently convinced of its importance that they have begun promoting this methodology as a “best practice” at the World of Concrete and ConAgg industry conventions.
Use of 5-HT1 Agonists in Pregnancy
Authors: Evans Emily W , Lorber Kristin C 
Published: March 2008

OBJECTIVE: To report and evaluate available data on the use of serotonin 5-HT1 agonists (triptans) during pregnancy. DATA SOURCES: A PubMed search, limited to English-language articles on human subjects, was conducted (1990–December 2007) using the search terms pregnancy, migraine, and the individual triptan drug names. In addition, the manufacturers of all 7 available triptans were contacted regarding the existence of a pregnancy registry for their drug(s) and the availability of registry reports. STUDY SELECTION AND DATA EXTRACTION: All retrospective and prospective studies reporting on pregnancy outcomes after the use of a triptan were included and critically evaluated. Data from all available manufacturer-sponsored pregnancy registries were also included. DATA SYNTHESIS: Safe and effective treatment of migraine during pregnancy is imperative. Data involving sumatriptan and, to a lesser extent, naratriptan and rizatriptan, exist primarily regarding exposure in the first trimester. These data show no significant differences in congenital malformations or poor pregnancy outcomes when compared with expected rates in the general population or with the observed rates in control subjects. There is very little information regarding exposure in middle and late pregnancy. CONCLUSIONS: Sumatriptan appears to be a safe treatment alternative for pregnant women who experience new-onset or worsened migraines in the first trimester. Further observation is needed prior to recommending its use in later trimesters. Based upon available data, the other agents in this class cannot be recommended for use during pregnancy at this time.
Catalyst Stability Determines the Catalytic Activity of Non‐Heme Iron Catalysts in the Oxidation of Alkanes
Authors: England Jason , Davies Catherine R. , Banaru Maria , White Andrew J. P. , Britovsek George J. P. 
Published: March 2008

AbstractA series of iron(II) bis(triflate) complexes [Fe(L)(OTf)2] containing linear tetradentate bis(pyridylmethyl)diamine ligands with a range of ligand backbones has been prepared. The backbone of the ligand series has been varied from a two‐carbon linkage [ethylene (1), 4,5‐dichlorophenylene (2) and cyclohexyl (3)] to a three‐carbon [propyl (4)) and a four‐carbon linkage (butyl (5)]. The coordination geometries of these complexes have been investigated in the solid state by X‐ray crystallography and in solution by 1H and 19F NMR spectroscopy. Due to the labile nature of high‐spin iron(II) complexes in solution, dynamic equilibria of complexes with different coordination geometries (cis‐α, cis‐β and trans) are observed with ligands 2–5. In these cases, the geometry observed in the solid state does not necessarily represent the only or even the major geometry present in solution. The ligand field strength in the various complexes has been investigated by variable temperature magnetic moment measurements and UV‐vis spectroscopy. The strongest ligand field is observed with the most rigid ligands 1 and 2, which generate complexes [Fe(L)(OTf)2] with a cis‐α coordination geometry and the corresponding complexes [Fe(L)(CH3CN)2]2+ display spin crossover behaviour. The catalytic properties of the complexes for the oxidation of cyclohexane, using hydrogen peroxide as the oxidant, have been investigated. An increased flexibility in the ligand results in a weaker ligand field, which increases the lability of the complexes. The activity and selectivity of the catalysts appear to be related to the strength of the ligand field and the stability of the catalyst in the oxidising environment.
Efficient and Practical Cross‐Coupling of Arenediazonium Tetrafluoroborate Salts with Boronic Acids Catalyzed by Palladium(0)/Barium Carbonate
Authors: Felpin François‐Xavier , Fouquet Eric 
Published: March 2008

AbstractThe cross‐coupling reaction of arenediazonium tetrafluoroborate salts with boronic acids catalyzed by the unusual palladium(0)/barium carbonate catalyst is described as an extremely practical and highly efficient alternative to classical homogeneous conditions. Reactions are conducted under mild conditions at room temperature without any base and ligand. The opportunity of preparing unsymmetrical terphenyls in a one‐pot process is also demonstrated. Finally, the power of this methodology is highlighted by the synthesis of Bifenazate.
Ring‐Closing Metathesis at Room Temperature within Nanometer Micelles using Water as the Only Solvent
Authors: Lipshutz Bruce H. , Ghorai Subir , Aguinaldo Grant T. 
Published: March 2008

AbstractSimply mixing a water‐insoluble diolefinic substrate and Grubbs second generation catalyst in pure water containing small amounts of the amphiphile polyoxyethanyl α‐tocopheryl sebacate (PTS) leads to efficient ring‐closing metathesis.
Carboxylic Acids as Substrates in Homogeneous Catalysis
Authors: Gooßen Lukas J. , Rodríguez Nuria , Gooßen Käthe 
Published: March 2008

AbstractIn organic molecules carboxylic acid groups are among the most common functionalities. Activated derivatives of carboxylic acids have long served as versatile connection points in derivatizations and in the construction of carbon frameworks. In more recent years numerous catalytic transformations have been discovered which have made it possible for carboxylic acids to be used as building blocks without the need for additional activation steps. A large number of different product classes have become accessible from this single functionality along multifaceted reaction pathways. The frontispiece illustrates an important reason for this: In the catalytic cycles carbon monoxide gas can be released from acyl metal complexes, and gaseous carbon dioxide from carboxylate complexes, with different organometallic species being formed in each case. Thus, carboxylic acids can be used as synthetic equivalents of acyl, aryl, or alkyl halides, as well as organometallic reagents. This review provides an overview of interesting catalytic transformations of carboxylic acids and a number of derivatives accessible from them in situ. It serves to provide an invitation to complement, refine, and use these new methods in organic synthesis.
Negative air ions releasing properties of tourmaline contained ethylene propylene diene terpolymer/polypropylene thermoplastic elastomers
Authors: Yeh Jen‐taut , Wei Wei , Hsiung Han‐hsing , Jiang Tao 
Published: March 2008

AbstractThe releasing properties of negative air ions of tourmaline contained polypropylene (PP) and ethylene propylene diene terpolymer/polypropylene (EPDM/PP) composite films under varying testing conditions were investigated in this study. It is interesting to note that the Cion− values of EPDM/PP/tourmaline specimens tested at varying conditions are significantly higher than those of the PP/tourmaline specimens with the same loadings of tourmaline powders. Moreover, all Cion− values of PP/tourmaline and EPDM/PP/tourmaline film specimens tested at dynamic impact mode are significantly higher than those of the corresponding specimens tested at static mode but the same temperature. A beneficial temperature effect on Cion− values of the PP/tourmaline and EPDM/PP/tourmaline film specimens tested at static and dynamic impact conditions was found. To understand these interesting negative air ion properties of PP/tourmaline and EPDM/PP/tourmaline film specimens, energy dispersive X‐rays analysis of the tourmaline powders, scanning electron microscope morphology, and tensile property analysis of the PP/tourmaline and EPDM/PP/tourmaline film specimens were performed. Possible reasons account for the interesting negative air ion properties of the PP/tourmaline and EPDM/PP/tourmaline film specimens are discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
New optically active poly(amide‐imide)s based on N,N′‐(pyromellitoyl)‐bis‐L‐amino acid and 1,3‐bis(4‐aminophenoxy) propane: Synthesis and characterization
Authors: Faghihi Khalil 
Published: March 2008

AbstractFive new poly(amide‐imide)s 8a–e were synthesized through the direct polycondensation reaction of five chiral N,N′‐(pyromellitoyl)‐bis‐L‐amino acids 3a–e with 1,3‐bis(4‐aminophenoxy) propane 7 in a medium consisting of N‐methyl‐2‐pyrrolidone, triphenyl phosfite, calcium chloride, and pyridine. The polycondensation reaction produced a series of novel poly(amide‐imide)s containing trimethylene moiety in the main chain in high yield with inherent viscosities between 0.34 and 0.65 dL/g. The resulted polymers were fully characterized by means of FTIR spectroscopy, elemental analyses, inherent viscosity, and solubility tests. Thermal properties of these polymers were investigated by using thermal gravimetric analysis (TGA) and differential thermal gravimetric (DTG). All of the polymers were soluble at room temperature in polar solvents such as N,N‐dimethyl acetamide, N,N‐dimethyl formamide, dimethyl sulfoxide, and N‐methyl‐2‐pyrrolidone. N,N′‐(pyromellitoyl)‐bis‐L‐amino acids 3a–e were prepared in quantitative yields by the condensation reaction of pyromellitic dianhydride (1,2,4,5‐benzenetetracarboxylic acid 1,2,4,5‐dianhydide) 1 with L‐alanine 2a, L‐valine 2b, L‐leucine 2c, L‐isoleucine 2d, and L‐phenyl alanine 2e in acetic acid. Also 1,3‐bis(4‐aminophenoxy) propane 7 was synthesized by using a two‐step reaction. At first 1,3‐bis(4‐nitrophenoxy) propane 6 was prepared from the reaction of 4‐nitrophenol 4 with 1,3‐dibromoprapane 5 in NaOH solution. Then, dinitro compound 6 was reduced by using Na2S. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effects of ionizing radiation in ethylene‐vinyl alcohol copolymers and in composites containing microfibrillated cellulose
Authors: Fernández Avelina , Sánchez M. Dolores , Ankerfors Mikael , Lagaron Jose M. 
Published: March 2008

AbstractThis study reports on the effect of gamma radiation on morphological, thermal, and water barrier properties of pure ethylene vinyl alcohol copolymers (EVOH29 and EVOH44) and its biocomposites with the nanofiller microfibrillated cellulose (2 wt %). Added microfibrillated cellulose (MFC) preserved the transparency of EVOH films but led to a decrease in water barrier properties. Gamma irradiation at low (30 kGy) and high doses (60 kGy) caused some irreversible changes in the phase morphology of EVOH29 and EVOH44 copolymers that could be associated to crosslinking and other chemical alterations. Additionally, the EVOH copolymers and the EVOH composites reduced the number of hygroscopic hydroxyl functionalities during the irradiation processing and novel carbonyl based chemistry was, in turn, detected. As a result of the above alterations, the water barrier properties of both neat materials and composites irradiated at low doses were notably enhanced, counteracting the detrimental effect on water barrier of adding MFC to the EVOH matrix. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Swelling and diffusion characteristics of polar and nonpolar polymers in asphalt
Authors: Upadhyay Shivendra , Mallikarjunan Vishwanath , Subbaraj Vaideesh K. , Varughese Susy 
Published: March 2008

AbstractThe swelling and diffusion characteristics of a polar polymer [ethylene vinyl acetate (EVA)] and a nonpolar polymer [low‐density polyethylene (LDPE)] were studied with swelling experiments of the polymers in asphalt at different temperatures. The study showed that the diffusion mechanisms for LDPE and EVA were different and temperature‐dependent. In the case of LDPE, the observed diffusion was anomalous at both swelling temperatures (70 and 90°C). LDPE at 90°C showed sigmoidal solvent‐uptake behavior during the initial period of swelling and a sorption overshoot in a later period. EVA showed Fickian transport at 60°C and anomalous diffusion at a higher swelling temperature (70°C) with sigmoidal uptake behavior. An analysis of the diffusion coefficients and the Fourier transform infrared results showed that the diffusing molecules were different in the case of LDPE and EVA, and there were possible polymer–asphalt interactions. Differential scanning calorimetry and swelling studies showed that penetrant‐induced crystallization affected the diffusion process in the case of LDPE. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of solvents in radiation‐induced grafting of 4‐vinyl pyridine onto fluorinated ethylene propylene copolymer
Authors: Rath S. K. , Palai A. , Rao Swati , Chandrasekhar L. , Patri M. 
Published: March 2008

AbstractA wide range of solvents have been examined to find their effect on radiation‐induced grafting of 4‐vinyl pyridine onto fluorinated ethylene propylene copolymer by simultaneous irradiation technique. The effect of solvent on percentage of grafting has been monitored by varying monomer concentration and total dose of radiation. Further grafting results have been correlated with the solubility parameter of the solvent and solvent mixtures. Evidence of grafting has been based on characterization of grafted samples in terms of FTIR, EDAX, X‐ray mapping, thermogravimetric analysis, and dynamic mechanical analysis. Depth profiling of a few representative grafted films were studied by viewing the cross‐sectional distribution of elemental nitrogen using SEM‐EDAX. The results suggest that with increase in grafting the grafting front propagates from the surface toward bulk, thus establishing the frontal mechanism of radiation grafting. Furthermore, the grafted films were characterized for their surface properties using contact angle goniometry. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Seeding as a means of controlling particle size in dispersion polymerization
Authors: Jiang Sheng , Sudol E. David , Dimonie Victoria L. , El‐Aasser Mohamed S. 
Published: March 2008

AbstractTwo distinctively different seeded dispersion polymerization processes employing micron and submicron size seed particles, respectively, have been used to gain a better mechanistic understanding of the dispersion polymerization process. Using monodisperse micron‐size PMMA particles as seed, it was found that when low monomer/polymer ratios (M/P < 2.50) were used in methyl methacrylate (MMA) seeded dispersion polymerizations, particle growth dominates and the number of particles remains unchanged (i.e., narrow distributions are preserved). However, when higher M/P ratios (>2.50) were applied, bimodal or trimodal particle size distributions were produced, which is considered to result from the competition between particle growth and secondary nucleation. When small amounts of submicron seeds were used with the initial intention of gaining a better understanding of the nucleation process, it was surprisingly found that the final number of micron size particles was nearly the same as the initial number of submicron seed particles over a relatively wide range of reaction conditions, including seed, initiator, stabilizer, and monomer concentrations, and the medium composition. These results indicate that within certain limits seeded dispersion polymerization can be a more robust means of controlling particle size thanab initiodispersion polymerization in terms of reproducibly producing a target particle size. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Dispersion characterization in layered double hydroxide/Nylon 66 nanocomposites using FIB imaging
Authors: Zhu Y. D. , Allen G. C. , Adams J. M. , Gittins D. , Herrero M. , Benito P. , Heard P. J. 
Published: March 2008

AbstractLayered double hydroxides (LDHs), a newly emerging 2D host material, consist of cationic brucite‐like layers and exchangeable interlayer anions. In this work, the morphology and dispersion of LDH particles in LDH/Nylon 66 (salt) nanocomposites has been investigated using focused ion beam (FIB) techniques, transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The FIB images show that LDHs are present in the polymer phase dispersed to different degrees, with partial intercalation, exfoliation, and aggregation all being observed. The most even dispersion was achieved in nanocomposites with the lowest loading (0.5 wt % LDH). Residual tactoids and agglomerates were most common in the samples made with the highest concentration of LDHs studied here (5 wt %). The dispersion observed using FIB was consistent with TEM and XRD analysis, yet this technique had significant benefits in terms of time and simplicity over these “conventional” technologies. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Implications for tooth development on ENU‐induced ectodermal dysplasia mice
Authors: Kim Yeun‐Jung , Kim Jae‐Young , Cho Jae‐Woo , Cha Dal‐Sun , Lee Min‐Jung , Osamu Tadokoro , Kwon Hyuk‐Jae , Cho Kyu‐Hyuk , Lee Joon H. , Song Chang‐Woo , Jung Han‐Sung 
Published: March 2008

AbstractBACKGROUND: In this study, the mutated phenotypes were produced by treatment of chemical mutagen, N‐ethyl‐N‐nitrosourea (ENU). We analyzed the mutated mice showing the specific phenotype of ectodermal dysplasia (ED) and examined the affected gene. METHODS: Phenotypes, including size, bone formation, and craniofacial morphology of ENU‐induced ED mice, were focused. Tooth development and expression of several molecules were analyzed by histologic observations and immunohistochemistry. We carried out genome‐wide screening and quantitative real‐time PCR to define the affected and related genes. RESULTS: As examined previously in human ectodermal dysplasia, ENU‐induced ED mice showed the specific morphologic deformities in tooth, hair, and craniofacial growth. Tooth development in the ENU‐induced ED mice ceased at early cap stage. In addition, skeletal staining showed retardation in craniofacial development. Finally, the affected gene, which would be involved in the mechanism of ED, was located between the marker D3Mit14 and D3Mit319 on chromosome 3. CONCLUSIONS: The affected gene in ENU‐induced ED mice showed several defects in ectodermal organogenesis and these results indicate that this gene plays an important role in mouse embryogenesis. Birth Defects Res (Part B) 2008. © 2008 Wiley‐Liss, Inc.