bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanovalves
Authors: Saha S. , Leung K. C.‐F. , Nguyen T. D. , Stoddart J. F. , Zink J. I.
Published: February 2007

This article features both molecular and supramolecular chemistry involving: i) stimuli‐induced nanoscale movements within mechanically interlocked molecules; ii) the fabrication of mesoporous silica substrates; and iii) the integration of the mechanically interlocked molecular/supramolecular actuators to act as gatekeepers at the entrances to the silica nanopores into which guest dye molecules can be uploaded and released on demand from the mesoporous silica substrates. The supramolecular actuators are based on two [2]pseudorotaxanes—that is, 1:1 complexes that can be dissociated by external inputs, such as acid/base cycles, electrons, and light. The molecular actuators are based on bistable [2]rotaxanes and can be operated mechanically by using either redox chemistry or electrochemistry. After these pseudorotaxanes and bistable rotaxanes have been attached covalently to the orifices of the silica nanopores, stimuli‐controlled mechanical movements within these mechanically interlocked molecules can be harnessed to close and open the nanopores. Therefore, these mechanically interlocked molecules have been employed as nanovalves for controlled sequestering and release of guest dye molecules into and out of the mesoporous silica substrates. These actuators can be regarded as the prototypes of highly controllable drug‐delivery systems.
Rate Acceleration of Light‐Driven Rotary Molecular Motors
Authors: Pollard M. M. , Klok M. , Pijper D. , Feringa B. L.
Published: February 2007

One of the key challenges in taking light‐driven unidirectional rotary motors from discovery to application is to increase the rate of rotation. Herein, we review our ongoing efforts to address this issue by meticulous improvement to the molecular design. To accelerate the rotary cycle, we have focused primarily on the rate‐limiting thermal isomerization step. This has been a fascinating and formidable objective, given that the first system we reported had a half‐life of over one week at room temperature! Our research has ultimately led to the construction of a unidirectional rotary molecular motor with a cycle 108 times faster than the original; that is, it can in principle function at 44 rotations per second.
Cover Picture: Microsolidics: Fabrication of Three‐Dimensional Metallic Microstructures in Poly(dimethylsiloxane) (Adv. Mater. 5/2007)
Authors: Siegel A. C. , Bruzewicz D. A. , Weibel D. B. , Whitesides G. M.
Published: February 2007

Flexible metallic wires embedded in poly(dimethylsiloxane) are produced with microscale dimensions by injecting heated, liquid solder into microfluidic channels and cooling, as reported by George Whitesides and co‐workers on p. 727. This approach is used to fabricate complex, metallic microstructures that are twisted (as shown), rolled, or woven into fabrics. The structures can be rigid or flexible, depending on the type of solder used, and breaks in the metal can be “healed” by reheating the device. This method of fabrication may find applications in flexible electronic circuits, 3D metallic microstructures, and hybrid electronic–microfluidic devices.
Photocatalytic oxidation of nitrobenzene and phenylamine: Pathways and kinetics
Authors: Palmisano Giovanni , Loddo Vittorio , Augugliaro Vincenzo , Palmisano Leonardo , Yurdakal Sedat
Published: February 2007

The oxidation of nitrobenzene and phenylamine has been carried out by heterogeneous photocatalysis in aqueous suspensions of commercial TiO2. The photoreactivity results indicate that two reaction pathways occur in parallel with both substrates from the start of irradiation: partial oxidation to monohydroxy derivatives and mineralization. The first pathway involves the entering of radical HO• into the aromatic ring giving rise to monohydroxy derivatives, and the second one involves the total oxidation of the substrates to CO2. The partial oxidation of nitrobenzene produces all the three possible monohydroxy derivatives, while that of phenylamine only produces the ortho‐ and para‐isomers. The extent of adsorption in the dark was found to be about 8% mol for nitrobenzene, while the amounts were not detectable for phenylamine. The Langmuir‐Hinshelwood approach has been satisfactorily applied for modeling the photoreactivity results, and the values of the kinetic model parameters have been determined. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Biporous polymeric microspheres coupled with mercaptopyridine for rapid chromatographic purification of plasmid DNA
Authors: Li Yuan , Dong Xiao‐Yan , Sun Yan
Published: February 2007

A biporous absorbent coupled with mercaptopyridine was synthesized for the purification of plasmid DNA. Analyses by scanning electron microscopy and mercury intrusion porosimetry revealed that the matrix contained two families of pores, i.e., micropores and superpores. The superpores provided not only convective flow channels for the mobile phase, but also a large surface for biomacromolecules binding. So the chromatographic process can be operated at high flow rate with high column efficiency and low backpressure as identified on a 2‐mL column. When 10 mL crude feedstock containing 3 mg of plasmid (5.4 kb pcDNA3) was loaded at a flow rate as high as 20 cm/min, the separation was finished in 10 min, and the plasmid was completely recovered with undetectable impurities of nucleic acids and proteins. The productivity was determined to be 9.0 g/L h, comparable to the pDNA productivity obtained using the commercial column. These results indicate that the biporous medium is promising for high‐throughput purification of plasmid DNA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2205–2211, 2007
Soap‐free emulsion copolymerization of perfluoroalkyl acrylates in the presence of a reactive surfactant
Authors: Tingting Yang , Hui Peng , Shiyuan Cheng , Park In Jun
Published: February 2007

Soap‐free emulsion copolymerization of perfluoroalkyl acrylate (FA)/methyl methacrylate (MMA)/n‐butyl acrylate (n‐BA) was carried out in the presence of sodium 2‐acrylamide‐2‐methyl propanesulfonate (AMPSNa) as a reactive surfactant and potassium persulfate (KPS) as an initiator. An analysis of the effects of concentration of AMPSNa, KPS, FA as well as polymerization temperature on the kinetic features (rate of polymerization) and colloidal characteristics (mean particle diameter, particle disperse index, particle numbers, and surface charge density) was followed. NMR, FTIR, AFM, and fluorine‐selective electrode analysis were used to characterize the composition and morphology of the FA copolymers. Both AFM analysis and contact angle measurements strongly implied that the fluorinated segments migrated to the outmost surface and created films with lower surface energy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2438–2444, 2007
Enhancement of the water repellency durability of the fabrics treated by fluorinated nanocopolymer emulsions
Authors: Huang Pei‐Yuan , Chao Yu‐Chou , Liao Yih‐Tyan
Published: February 2007

The fluorinated copolymer emulsions containing different monomers with the reactive groups were successfully prepared at our lab, using emulsion polymerization technique. The water repellency and the durability for the fabrics treated by fluorinated water repellents after 30 and 50 washes were measured and compared. Actually, the combination of the comonomers containing blocked isocyanate or other reactive groups after copolymerization would increase the durability of the water repellency. In addition, the blocked isocyanate crosslinking agent (Jintexguard FCN) does, indeed, substantially increase the durability also. It clearly indicates that the copolymer emulsion prepared by the reaction of fluorinated acrylate, cyclohexyl methacrylate, and 3‐chloro‐2‐hydroxy‐propyl methacrylate(Topolene M) with monomers containing blocked isocyanate group(Jintexan BIA) showed very good durability. More importantly, the combination of this copolymer and Jintexguard FCN will significantly provide excellent water repellency and durability after 50 washes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2451–2457, 2007
Migration resistant polymeric plasticizer for poly(vinyl chloride)
Authors: Lindström Annika , Hakkarainen Minna
Published: February 2007

Flexible films of poly(vinyl chloride) (PVC) and linear or branched poly(butylene adipate) (PBA), synthesized from 1,4‐butanediol and adipic acid or dimethyl ester of adipic acid, were aged in an aqueous environment for 10 weeks to study how branching, molar mass, and end‐group functionality affect the leaching of polyester plasticizer from thin films. Principal component analysis was applied to reveal patterns and correlations between mechanical properties, material characteristics, and aging behavior. Introduction of branches in the polyester structure increased the miscibility between PVC and the polyester, resulting in improved mechanical properties and lower water absorption. Methyl ester end‐group in PBA polyester stabilized the polymeric plasticizer toward hydrolysis, and reduced the formation and migration of monomeric degradation products from the blends during aging in water. The combination of branched structure with methyl ester end‐groups resulted in a migration resistant polymeric plasticizer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2458–2467, 2007
Transient effects in dynamic modulus measurement of silicone rubber, part 2: Effect of mean strains and strain history
Authors: Warley R. L. , Feke D. L. , Manas‐Zloczower I.
Published: February 2007

The strain‐dependent dynamic storage modulus of a poly(dimethyl‐siloxane‐co‐methylvinyl‐siloxane‐co‐methylphenyl‐siloxane)‐based silicone elastomer (PVMQ), which is reinforced with fumed silica and crosslinked with peroxide, is investigated. The time dependence of the dynamic storage modulus on the magnitude of the mean strain at a particular test condition is investigated. The dynamic modulus results are shown to depend on the time of cycling as well as the relative magnitudes of the dynamic and mean strains. The relaxation of the force required to maintain the mean strain is observed to depend on the magnitude of the dynamic strains and the data are shown to be consistent with static stress relaxation experiments in the limit of zero dynamic strain. Recovery of the dynamic modulus from the exposure to higher strain cycling is seen to be facilitated by dynamic cycling with higher cycling strains yielding faster recovery rates. The observed phenomena are interpreted in terms of the role of entanglements in the polymer phase on the dynamic behavior of the elastomer material. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2197–2204, 2007
Influence of binding interface between active and support layers in composite PDMS membranes on permeation performance
Authors: Shi Er , Huang Weixing , Xiao Zeyi , Li Donghuai , Tang Ming
Published: February 2007

Effect of the binding interfaces of composite polydimethylsiloxane (PDMS) membranes on their pervaporation performance was studied. The membranes were made up of PDMS as active skin layer and polysulfone (PSF) or polyamide (PA) as supporting layer. PDMS‐PSF membrane was numbered 1, and PDMS‐PA membrane numbered 2. The pervaporation experiments were carried out by using the composite membranes and dilute ethanol–water mixture. The experimental measurements for the permeation performance under various operating conditions (e.g., feed concentration and temperature) showed that the specific permeation rate of membrane 2 was over membrane 1 by seven times at least. A resistance‐in‐series model was applied to formularize the transport of the permeants. Influence of the binding interfaces between the active skin layer and support layers in these membranes on pervaporation performance was analyzed. The cross section morphology of the membranes and chemical element distribution along membrane thickness were examined by using SEM and EDS. It was found that, although the PDMS intrusion layer into PSF near the interface was only about 2 μm, it gave significant effect on the permeation performance. It implied that the resistance produced by the intrusion layer into PSF was apparently larger than that of PDMS intruding PA and over intrinsic PDMS resistance. These should be probably attributed to structures and formation of the binding interfaces. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2468–2477, 2007
Use of different size grids to control the surface chemistry of plasma‐polymerized acrylic acid films in a hybrid discharge
Authors: Dhayal Marshal
Published: February 2007

The surface chemistry of plasma‐polymerized acrylic acid (ppAc) films were controlled in a two‐stage (primary and processing) hybrid radio frequency (RF) discharge by changing the grid wire spacing (ds). Two regions were defined in terms of ds with respect to Debye length (λd) in the primary chamber at the grid to control the electron temperature (Te) and surface chemistry of the ppAc films deposited in the processing chamber. A higher Te (>3 eV) in the processing plasma was possible for ds > λd, whereas decreasing ds relative to λd reduced Te. X‐ray photoelectron spectroscopy was used to characterize the ppAc films deposited on a glass substrate. The ppAc films surface characterization showed the maximum proportion of carbon atoms as carboxylic/ester [C(O)OX] functionalities in C1s at the surface of films for the grid with ds ≈ λd. The proportion of carbon atoms as [C(O)OX] and COX in C1s at the surface decreased when ds decreased relative to λd. The proportion of carbon atoms as carbonyl (CO) at the film surface showed very good stability for all of the ds values explored in this study. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2219–2224, 2007
Thermal fractionation and properties of different polyethylene/wax blends
Authors: Hato M. J. , Luyt A. S.
Published: February 2007

The influence of paraffin‐wax type and content on the properties of its blends with HDPE, LDPE, and LLDPE was investigated. Melt‐mixing of HDPE with wax gave rise to completely miscible blends for both 10 and 20% wax contents. A wax content of 30% gave rise to a partially miscible blend. These observations were supported by the thermal fractionation (stepwise cooling) results. Melt‐mixing of LDPE with hard paraffin wax gave rise to a partially miscible blend for all wax contents investigated, while complete miscibility was observed for the 10% oxidized hard paraffin wax containing blend. Complete miscibility was observed for all the LLDPE/A1 wax blends, with A1 wax as an oxidized hard paraffin wax. This indicates possible cocrystallization of this wax with LLDPE, which was also evident from the thermal fractionation curves. LLDPE blends with hard paraffin wax were, however, partially miscible for all wax contents. All the observations were supported by the surface free energy results. It is further clear from the thermal fractionation results that the presence of wax changed the crystallization behavior of LDPE and LLDPE. Changes in the tensile properties are explained in terms of the miscibility and proposed morphologies of the blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2225–2236, 2007
Modification of rubber powder with peroxide and properties of polypropylene/rubber composites
Authors: Shanmugharaj A. M. , Kim Jin Kook , Ryu Sung Hun
Published: February 2007

Waste tire powder was functionalized in the presence of various concentrations of allylamine and benzoyl peroxide. Fourier transform infrared spectroscopy studies confirmed the presence of allylamine on the surface of the rubber powder. The surface energy of the functionalized rubber powder revealed that the introduction of allylamine onto the rubber powder surface increased the surface activity. Improvements in the tensile strength, elongation at break, and storage modulus were observed for polypropylene/modified rubber powder/maleic anhydride grafted polypropylene, and this was attributed to an improvement in the compatibility due to the chemical interaction between the rubber powder and compatibilizer. Evidence for the reaction between the rubber surface and compatibilizer was observed in Fourier transform infrared studies. This peroxide‐initiated monomer‐grafting technique is feasible for large‐scale processes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2237–2243, 2007
Hemodialysis membranes prepared from poly(vinyl alcohol): Effects of the preparation conditions on the morphology and performance
Authors: Barzin J. , Madaeni S. S. , Pourmoghadasi S.
Published: February 2007

Poly(vinyl alcohol) was employed for the preparation of hemodialysis membranes with and without the addition of acetic acid and poly(ethylene glycol) with the phase‐inversion process. Aqueous solutions of sodium sulfate and sodium hydroxide were chosen as coagulant baths. The performances of the membranes were estimated by the measurement of the removal of uremic toxins (urea, uric acid, and creatinine) from human blood serum. The morphologies of the membranes were investigated and correlated to the membrane performance. Increasing the poly(ethylene glycol) concentration in the polymer solutions resulted in porous, spongelike structures because of the higher polarity of the polymer solutions and the enhancement of the diffusion rate of the nonsolvent (sodium sulfate and sodium hydroxide) into the polymer solutions. The porous structures of the membranes enhanced the removal of uremic toxins. The presence of acetic acid, with greater ionization strength, resulted in higher electrostatic interactions between positive and negative ions in the coagulation baths and polymer solutions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2490–2497, 2007
Effects of stretching on crystalline phase structure and morphology of hard elastic PVDF fibers
Authors: Du Chun‐hui , Zhu Bao‐Ku , Xu You‐Yi
Published: February 2007

The phase characteristics and morphology of stretched hard elastic poly(vinylidene fluoride) (PVDF) fibers were investigated by X‐ray diffraction (XRD) and wide‐angle and small‐angel X‐ray scattering (WAXS and SAXS). It was indicated that α and β phases coexisted in stretched PVDF fibers, stretching assisted in α to β phase transformation. The β/α ratios of stretched PVDF fibers were affected by stretching temperature, rate, and ratio. The β phase content of stretched PVDF fibers had an abrupt increase when stretched near 70°C, and then it decreased with increasing stretching temperature. Besides, the β/α ratio of PVDF fibers increased with stretching rate and ratio. The total crystallinity of PVDF fibers did not change much even on different stretching conditions. WAXS results indicated that the unstretched and stretched PVDF fibers all exhibited three strong equatorial streaks, with d‐spacing (0.964, 0.488, and 0.439 nm) and (0.946, 0.494, and 0.480 nm), which suggested that PVDF fibers still remained the crystalline reflections of c‐axis orientation even after being stretched. The long periods of stretched PVDF fibers, calculated from SAXS curves, increased from 19.04 to 39.75nm. On the basis of these results, the β transformation mechanism of stretched PVDF fibers was also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2254–2259, 2007
Temporal evolution of phase morphology of polypropylene/poly(ethylene octene) elastomer binary polymer blends by phase contrast microscope
Authors: Xu Xinhua , Zhu Tianbing , Yan Xueliang , Zhang Chunhuai
Published: February 2007

Blend films of polypropylene/poly(ethylene‐octane) at various mixing times are prepared by freezing‐microtome. The temporal evolution of their phase morphologies is investigated by phase contrast microscope (PCM). The digital image analysis, which contains the analysis in both real and wave‐number space, is introduced to deal with the PCM graphs. The characteristic length, L in real space, the average domain spacing, and the average chord lengths in wave‐number space, are used to express the domain sizes of two phases. The temporal evolution of phase morphology reaches the dynamic equilibrium between breakup and coalescences of domains at the late stage of mixing. In addition, two different fractal dimensions are defined to discuss the symmetry of the distribution of dispersed phase domains and the distribution uniformity: Df for the symmetry and Dc for the uniformity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Novel hybrid of clay, cellulose, and thermoplastics. I. Preparation and characterization of composites of ethylene–propylene copolymer
Authors: Pratheep Kumar Annamalai , Pal Singh Raj
Published: February 2007

The present study is aimed to prepare hybrid materials by incorporating layered silicates and microcrystalline cellulose into thermoplastic polymer. Using ethylene–propylene (EP) copolymer as thermoplastic polymer matrix and maleated EP (MEP) copolymer as compatibilizer, three types of composites were prepared by (i) melt mixing of cellulose with thermoplastics [I], (ii) melt mixing of clay with thermoplastics [II], and (iii) melt mixing of cellulose with the thermoplastic clay nanocomposites [III]. They were characterized by X‐ray diffractometry (XRD), differential scanning calorimetry, thermogravimetric analysis, and Fourier transform infrared spectroscopy. Instron was used to measure the mechanical properties. The composites [II] and [III] that contain layered silicates were intercalated nanocomposites as confirmed by XRD and transmission electron microscopy. The improvement in tensile properties was observed in cellulose–fiber‐reinforced composites with increasing cellulose content. In nanocomposites [II] and [III], the tensile modulus was improved. The resistance of the cellulose composites [I] for water absorption decreased with increasing content of cellulose fibers. The incorporation of layered silicates reduced the water absorption of cellulose composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2672–2682, 2007
Surface modification of natural rubber film by UV‐induced graft copolymerization with methyl methacrylate
Authors: Anancharungsuk W. , Tanpantree S. , Sruanganurak A. , Tangboriboonrat P.
Published: February 2007

Methyl methacrylate (MMA) was directly grafted on natural rubber (NR) or sulfur prevulcanized (SP) NR surface. The rubber sheet was primarily treated with argon plasma, followed by exposure to air for generating active functional groups. After immersing in a mixture of 30% hydrogen peroxide and MMA in ethanol and water (1 : 1), the MMA grafting took place after UV‐irradiation for 30–120 min. Results from the contact angle measurement and attenuated total reflection–Fourier transform infrared (ATR‐FTIR) spectroscopy showed that the highest amount of MMA grafting was achieved when using 13 wt % of MMA and UV irradiation time of 60 min. The tensile strength and percentage elongation at break of the modified SPNR sheet, having similar MMA grafting to that of NR, were in acceptable range as indicated in the standard glove's test (ASTM D3577). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2270–2276, 2007
Physical properties of water‐borne polyurethane blended with chitosan
Authors: Lin Y. H. , Chou N. K. , Wu W. J. , Hsu S. H. , Whu S. W. , Ho G. H. , Tsai C. L. , Wang S. S. , Chu S. H. , Hsieh K. H.
Published: February 2007

Water‐borne polyurethanes based on 4,4‐diphenylmethane diisocyanate, poly(butylene adipate), and chain extender N‐methyldiethanolamine (MDEA) that provided tertiary amine groups were synthesized. The polyurethane–chitosan (PU/CS) blends can be dissolved in the acetic acid and cast into films. The mechanical properties including tensile strength and elongation, as well as the water absorption and thermal properties of the PU/CS films were evaluated. The tensile strength increased with the increased amount of chitosan, but the elongation decreased accordingly. The chitosan in the blends promoted the water absorption. Chitosan was more thermally‐stable than PU, as shown in the thermal gravity analysis. Chitosan also had higher crystallinity, as demonstrated by differential scanning calorimetry. The blends were partial compatible mixtures, based on the data obtained from a dynamic mechanical analysis. Biocompatibility test was conducted utilizing immortalized rat chondrocytes (IRC). After IRC were seeded onto the PU/CS films for 1.5 and 120 h, the number of cells was counted and the morphology of cells was observed by light microscopy and scanning electron microscopy. Blends containing 30% chitosan had more cells attached initially. However, the blends containing more than 70% chitosan appeared to promote the cell proliferation. IRC were round on PU/CS films with more PU, but spread when the chitosan content in blends was higher. Overall, PU/CS films with more chitosan had better mechanical properties as well as biocompatibility. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2683–2689, 2007
Synthesis, characterization, and in vitro degradation of star‐shaped P(ε‐caprolactone)‐b‐poly(L‐lactide)‐b‐poly(D,L‐lactide‐co‐glycolide) from hexakis [p‐(hydroxymethyl)phenoxy]cyclotriphosphazene initiator
Authors: Yuan Weizhong , Yuan Jinying , Huang Xiaobin , Tang Xiaozhen
Published: February 2007

Hexaarmed star‐shaped hydroxyl‐terminated poly(ε‐caprolactone) (PCL) was successfully synthesized via the ring‐opening polymerization of ε‐caprolactone (CL) with hexakis[p‐(hydroxymethyl)phenoxy]cyclotriphosphazene initiator and stannous octoate catalyst in bulk. The star‐shaped PCL with hydroxy end groups could be used as a macroinitiator for block copolymerization with L‐lactide (L‐LA). The star‐shaped triblock copolymer was synthesized by above‐mentioned hydroxyl‐terminated star‐shaped diblock PCL‐b‐PLLA, D,L‐lactide (D,L‐LA), and glycolide (GA). IR, 1H NMR, and GPC analysis showed that the star‐shaped block copolymers were successfully synthesized and the molecular weights and the unit composition of the star‐shaped block copolymers were controlled by the molar ratios of monomer to initiator. The triblock copolymer presented a three‐phase structure, namely, PCL crystalline, PLLA crystalline, and D,L‐PLAGA amorphous domains, which made the triblock copolymer different from the diblock copolymer and star‐shaped PCL in crystallizability and thermal behaviors. Then, the in vitro degradation behaviors of the copolymers were investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2310–2317, 2007
Use of recycled polystyrene with polyurethane in polymer network compositions
Authors: Leite André Leonardo , Kloss Juliana , Trindade Eduardo Marques , Barbosa Ronilson Vasconcelos , Cestari Antônio Reinaldo , Fragoso Eunice , Zawadzki Sônia Faria
Published: February 2007

Postconsumer polymer recycling is a technology that involves many fields of science. The production of plastics has increased in recent years, and the products have many applications. Because of this, waste plastics are also increasing, causing many environmental problems due to the slow rate of natural decomposition of synthetic polymers. Polymer chemistry and process engineering are good tools for decreasing the problems caused by inappropriate polymer disposal. The subject of this work was the preparation of polymer networks based on recycled polystyrene (in the crystal form, PS; or in the expanded form, EPS) and polyurethane. The compositions were prepared by reaction between the polyurethanes (PU) components in the presence of recycled PS or EPS dissolved in the styrene monomer containing benzoyl peroxide as a free radical initiator. 1,4‐butanediol (BDO) was used as chain extender for PU network. The compositions were characterized by the evaluation of mechanical properties, thermogravimetric analysis, and morphological analysis. The PS or EPS concentration used in the mixtures was in the 1–5 wt % range. The addition of PS or EPS changed the mechanical behavior as well as the final morphology of the compositions. The use of the PS/PU or EPS/PU network systems is a way of decreasing PS or EPS discards decreasing this environmental problem. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2714–2719, 2007
Conversion analysis of acrylated hyperbranched polymers UV‐cured below their ultimate glass transition temperature
Authors: Schmidt Lars Erik , Leterrier Yves , Schmäh Daniel , Månson Jan‐Anders E. , James David , Gustavsson Eva , Svensson Lennart S.
Published: February 2007

The photo‐curing behavior of reactive blends of dipentaerythritol penta/hexaacrylate (DPHA) with an acrylated hyperbranched polyester and an acrylated hyperbranched polyether was investigated by means of photo differential scanning calorimetry. The chemical conversion data was analyzed using an autocatalytic model with close attention paid to the influence of composition, UV intensity, and vitrification. The autocatalytic model was found to be relevant to describe autoacceleration and diffusion controlled reaction stages, as long as the polymers were not vitrified. It was shown that the reaction order and the autocatalytic exponent were independent of UV intensity, whereas the rate constant showed strong intensity dependence, and the maximal conversion showed weak intensity dependence. A criterion for vitrification onset was proposed as the occurrence of a third stage in the conversion process. The ultimate conversion was found to be 0.16 higher than the conversion at vitrification for all investigated multifunctional acrylates independent of composition and UV intensity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2366–2376, 2007
Numerical simulation of the spin‐draw process of poly(ethylene terephthalate) fibers
Authors: Oh Tae Hwan
Published: February 2007

Numerical simulation for the calculation of the profile developments of the spin‐draw process in the melt spinning of poly(ethylene terephthalate) was performed. Both spinning and drawing profiles were analyzed and included the structure development of birefringence and crystallinity in the draw line. By applying a simple model describing the continuous drawing process, we made it possible to simulate the spin‐draw process. The strain rate of the spinline had a broad distribution, and that of the draw line had a narrower peak. The calculated birefringence ranged from 0.176 to 0.192 and the crystallinity ranged from 0.37 to 0.44 with draw ratio. The birefringence profile had a similar pattern as the stress profile, and the crystallinity gently increased along the draw line more than the birefringence did. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2522–2527, 2007
Synthesis and gas permeability of novel fluorinated poly(phenylene‐co‐naphthalimide)s
Authors: Qiu Zhiming , Zhang Suobo , Li Wenmu
Published: February 2007

A new class of high‐performance polymers [poly(phenylene‐co‐naphthalimide)s] was prepared through the Ni(0) catalytic coupling of N‐(4‐chloro‐2‐trifluromethylphenyl)‐5‐chloro‐1,8‐naphthalimide and 2,5‐dichlorobenzophenone. The resulting copolymers exhibited high molecular weights (high inherent viscosities) and a combination of desirable properties such as good solubility in dipolar aprotic solvents, film‐forming capability, and mechanical properties. The glass‐transition temperatures of the copolymers ranged from 320 to 403°C and increased as the content of the naphthalimide moiety increased. Tough polymer films, obtained via casting from N‐methylpyrrolidone solutions, had tensile strengths of 64–107 MPa and tensile moduli of 3.4–4.7 GPa. The gas permeability coefficients of the copolymers were measured for H2, CO2, O2, CH4, and N2. They showed oxygen permeability coefficients and permeability selectivity of oxygen to nitrogen (permeability coefficient for O2/permeability coefficient for N2) in the ranges of 1.39–4.31 and 4.92–5.38 barrer, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2395–2402, 2007
Variations of the glass‐transition temperature in the imidization of poly(styrene‐co‐maleic anhydride)
Authors: Liu He‐Yang , Cao Kun , Yao Zhen , Li Bo‐Geng , Hu Guo‐Hua
Published: February 2007

The imidization of poly(styrene‐co‐maleic anhydride) (SMA) was conducted, and the glass‐transition temperatures (Tg's) of the resulting products were measured with differential scanning calorimetry. The contributions from functional groups of maleic anhydride, N‐phenylmaleamic acid, and N‐phenylmaleimide to Tg were examined. Tg increased in the order of SMA < styrene–N‐phenyl maleimide copolymer < styrene–N‐phenyl maleamic acid copolymer and followed the Fox equation. Tg of the imidized products of SMA could be controlled by the conversions of both ring‐opening and ring‐closing reactions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2418–2422, 2007
Effects of functional groups on the thermal properties of modified polystyrene
Authors: Ahmetli Gulnare , Cerit Alaaddin
Published: February 2007

Polystyrene is, after polyolefins, the most widespread polymer in both industry and everyday life, successfully replacing some raw natural materials. In this study, the chemical modification of polystyrenes of different molecular weights was performed with various functional group modifiers (epichlorohydrin, maleic anhydride, and acetic anhydride) in one stage and in the medium of the cationic catalyst BF3·O(C2H5)2 according to previous studies. The concentration of the functional groups bonded to the aromatic ring of the polymer as a result of the chemical modification of polystyrenes of different molecular weights depended on the molecular weight of the polymer, and more functional groups were bonded to lower molecular weight polystyrene. The effects of the functional groups bonded to the structure of the polymer on the thermal properties of modified polystyrene were investigated. The polystyrene that was modified by maleic anhydride was more stable against thermal destruction at high temperatures. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2549–2553, 2007
Up‐regulation of metastasis‐promoting S100A4 (Mts‐1) in rheumatoid arthritis: Putative involvement in the pathogenesis of rheumatoid arthritis
Authors: Klingelhöfer Jörg , Šenolt Ladislav , Baslund Bo , Nielsen Gitte Helle , Skibshøj Inge , Pavelka Karel , Neidhart Michel , Gay Steffen , Ambartsumian Noona , Hansen Birgitte Schmidt , Petersen Jørgen , Lukanidin Eugene , Grigorian Mariam
Published: February 2007

Objective

To examine the involvement of the metastasis‐inducing protein S100A4 (Mts‐1) in the pathogenesis of rheumatoid arthritis (RA).

Methods

Synovial tissue, synovial fluid, and plasma were obtained from RA and osteoarthritis (OA) patients who were undergoing joint surgery. Immunohistochemical and immunofluorescence analyses and enzyme‐linked immunosorbent assays were used to determine the locations and concentrations of S100A4. The conformational structure of S100A4 in plasma and synovial fluid was determined after fractionation by size‐exclusion chromatography, protein separation by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, and Western blot analysis. Expression of various S100 proteins in RA synovium was determined by immunofluorescence and double‐staining using specific anti‐S100 antibodies.

Results

We found an up‐regulation of S100A4 in cells infiltrating RA synovial tissue. Most cell types identified by cell‐specific markers (fibroblasts, immune cells, and vascular cells) contributed to the production of S100A4 in RA synovial tissue. The pattern of S100A4 expression differed significantly from that of the proinflammatory proteins S100A9 and S100A12, which were restricted to phagocytes and granulocytes. The up‐regulation of S100A4 in RA synovial tissue was consistent with the high concentrations of the protein in RA versus OA plasma (mean 1,100 versus 211 ng/ml) and synovial fluid (mean 1,980 versus 247 ng/ml). Moreover, we found that S100A4 in RA plasma and synovial fluid was present in bioactive multimeric (M‐S100A4) conformations, whereas in OA, the majority of extracellular S100A4 was detected as the less active dimeric form. Consistent with our observations in tumor models, extracellular S100A4 stabilized the p53 tumor suppressor in RA synovial fibroblast–like cells and affected the regulation of p53 target genes, including Bcl‐2, p21WAF, and Hdm‐2, as well as matrix metalloproteinases.

Conclusion

Overexpression of S100A4 in RA synovial tissue and its release as M‐S100A4 can influence p53 function and modulate the expression of several genes that are potentially implicated in the disease process. Thus, S100A4 might play an important role in the pathogenesis of RA and might represent a new target for the treatment of RA.
Suppression of inflammation and structural damage in experimental arthritis through molecular targeted therapy with PPI‐2458
Authors: Hannig Gerhard , Bernier Sylvie G. , Hoyt Jennifer G. , Doyle Beth , Clark Ed , Karp Russell M. , Lorusso Jeanine , Westlin William F.
Published: February 2007

Objective

To determine the disease‐modifying activity and mechanism of action of the orally available methionine aminopeptidase type 2 inhibitor, [(1R)‐1‐carbamoyl‐2‐methyl‐propyl]‐carbamic acid‐(3R,4S,5S,6R)‐5‐methoxy‐4‐[(2R,3R)‐2‐methyl‐3‐(3‐methyl‐but‐2‐enyl)‐oxiranyl]‐1‐oxa‐spiro [2.5] oct‐6‐yl ester (PPI‐2458), in a rat model of peptidoglycan–polysaccharide (PG‐PS)–induced arthritis.

Methods

Arthritis was induced in rats by administration of PG‐PS, causing tarsal joint swelling and histopathologic changes characteristic of rheumatoid arthritis (RA). PPI‐2458, a potent irreversible methionine aminopeptidase type 2 inhibitor, was administered orally every other day at 1, 5, or 10 mg/kg.

Results

In an in vitro osteoclastogenesis model, PPI‐2458 potently inhibited osteoclast differentiation and bone resorption. In the rat PG‐PS arthritis model, PPI‐2458 afforded significant protection against established disease after therapeutic dosing. This in vivo activity of PPI‐2458 was linked to the inhibition of methionine aminopeptidase type 2. Histopathologic assessment of affected joints showed improvement in processes of inflammation, bone resorption, and cartilage erosion, associated with significant improvement in all clinical indices. The protective effects of PPI‐2458 against bone destruction in vivo, including the structural preservation of affected hind joints, correlated with improvements in bone histomorphometric markers, as determined by microfocal computed tomography and a significant decrease in systemic C‐telopeptide of type I collagen, suggesting decreased osteoclast activity in vivo. Moreover, PPI‐2458 prevented cartilage erosion as shown by a significant decrease in systemic cartilage oligomeric matrix protein.

Conclusion

The findings of this study suggest that PPI‐2458 exerts disease‐modifying activity in experimental arthritis through its direct inhibition of several pathophysiologic processes of this disease. These results provide a rationale for assessing the potential of PPI‐2458 as a novel RA therapy.
Pharmacokinetics and pharmacodynamics of intravenous PEGylated recombinant mammalian urate oxidase in patients with refractory gout
Authors: Sundy John S. , Ganson Nancy J. , Kelly Susan J. , Scarlett Edna L. , Rehrig Claudia D. , Huang William , Hershfield Michael S.
Published: February 2007

Objective

To evaluate the efficacy, immunogenicity, and tolerability of intravenous (IV) PEGylated recombinant mammalian urate oxidase (PEG‐uricase) for the treatment of severe gout.

Methods

Single infusions of PEG‐uricase (at doses ranging from 0.5 mg to 12 mg) were administered to 24 patients (6 cohorts of 4 patients each) in a phase I clinical trial. Plasma uricase activity (pUox), the plasma urate concentration (pUAc), and the uric acid–to‐creatinine ratio (UAc:Cr) in urine were monitored for 21 days after dosing. Adverse events and the IgG antibody response to PEG‐uricase were followed up for 35 days.

Results

All patients completed the trial. Maximum pUox was linearly related to the IV dose of PEG‐uricase, the area under the curve (AUC) value increased linearly (up to a dose of 8 mg), and the pUox half‐life was 6.4–13.8 days. After doses of 4–12 mg, the pUAc fell within 24–72 hours, from a mean ± SD value of 11.1 ± 0.6 mg/dl to 1.0 ± 0.5 mg/dl; the AUC value for the pUAc was equivalent to maintaining the pUAc at 1.2–4.7 mg/dl for 21 days postinfusion. The UAc:Cr ratio in urine fell in parallel with the pUAc. IgG antibodies to PEG‐uricase, mostly IgG2 and specific for PEG, developed in 9 patients, who had more rapid enzyme clearance but no allergic reactions. All adverse events were mild to moderate, with gout flares being most common.

Conclusion

The bioavailability, efficacy, and tolerability of IV PEG‐uricase were greater than the bioavailability, efficacy, and tolerability observed in a previous phase I trial of subcutaneous PEG‐uricase. Infusing 4–12 mg of PEG‐uricase every 2–4 weeks should maintain the pUAc well below the therapeutic target of 6 mg/dl and greatly reduce renal uric acid excretion. This treatment could be effective in depleting expanded tissue urate stores in patients with chronic or tophaceous gout.
Limitations of therapy and a guarded prognosis in an american cohort of takayasu arteritis patients
Authors: Maksimowicz‐McKinnon Kathleen , Clark Tiffany M. , Hoffman Gary S.
Published: February 2007

Objective

To describe the clinical, laboratory, and radiographic manifestations of Takayasu arteritis (TA) in a cohort from the US, evaluate the response to interventions, remission and relapse rates, and disease progression, and compare these observations with those from other cohorts in the US, Japan, India, Italy, and Mexico.

Methods

Seventy‐five patients were retrospectively studied using a uniform database that included clinical, laboratory, and imaging data. Vascular imaging studies were performed at least yearly to monitor disease progression.

Results

Common manifestations at disease onset included loss or asymmetry of pulses (57%), limb blood pressure discrepancy (53%), and bruits (53%). Eleven percent of patients were asymptomatic prior to disease diagnosis. Initial angiographic studies showed aortic abnormalities in 79% of patients and frequent involvement of the subclavian (65%) and carotid (43%) arteries.

Ninety‐three percent of longitudinally followed patients attained disease remission of any duration, but only 28% sustained remission of at least 6 months' duration after prednisone was tapered to <10 mg daily. Both angioplasty and vascular surgery were initially successful, but recurrent stenosis occurred in 78% of angioplasty and 36% of bypass/reconstruction procedures. More than two‐thirds of patients had difficulty performing routine daily activities and approximately one‐fourth of all patients were unable to work.

Our cohort was similar to the National Institutes of Health, Italian, Japanese, and Mexican cohorts in terms of the predominance of female subjects and disease manifestations, but differed from the Indian cohort in that the latter group had a higher frequency of male subjects, abdominal aorta and renal artery involvement, and hypertension.

Conclusion

Although improvement of symptoms in TA usually follows glucocorticoid therapy, relapses usually occur with dosage reduction. Attempts to restore vascular patency are often initially successful, but restenosis occurs frequently. Chronic morbidity and disability occur in most patients with TA in the US.
Proinflammatory mediator–induced reversal of CD4+,CD25+ regulatory T cell–mediated suppression in rheumatoid arthritis
Authors: van Amelsfort Jocea M. R. , van Roon Joel A. G. , Noordegraaf Madelon , Jacobs Kim M. G. , Bijlsma Johannes W. J. , Lafeber Floris P. J. G. , Taams Leonie S.
Published: February 2007

Objective

We previously demonstrated that CD4+,CD25+ regulatory T (Treg) cells are present in increased numbers in the synovial fluid (SF) of rheumatoid arthritis (RA) patients and display enhanced suppressive activity as compared with their peripheral blood (PB) counterparts. Despite the presence of these immunoregulatory cells in RA, chronic inflammation persists. The purpose of the present study was to investigate whether particular proinflammatory mediators that are associated with RA could abrogate CD4+,CD25+ Treg–mediated suppression.

Methods

Monocyte phenotype was determined by flow cytometry and cytokine levels by enzyme‐linked immunosorbent assay. Magnetically sorted CD4+,CD25– and CD4+,CD25+ T cells derived from the PB and SF obtained from RA patients were stimulated alone or in coculture with anti‐CD3 monoclonal antibody (mAb) and autologous antigen‐presenting cells, in the absence or presence of anti‐CD28 mAb or the proinflammatory cytokines interleukin‐6 (IL‐6), tumor necrosis factor α (TNFα), or IL‐7.

Results

Monocytes from the SF of RA patients displayed increased expression of HLA class II molecules, CD80, CD86, and CD40 as compared with PB‐derived monocytes, indicating their activated status. Mimicking this increased costimulatory potential, addition of anti‐CD28 mAb to cocultures of CD4+,CD25– and CD4+,CD25+ T cells resulted in reduced CD4+,CD25+ Treg–mediated suppression in both PB and SF. Furthermore, IL‐7 and, to a limited extent, TNFα, both of which are produced by activated monocytes and were detected in SF, abrogated the CD4+,CD25+ Treg–mediated suppression. In contrast, IL‐6 did not influence Treg‐mediated suppression.

Conclusion

Our findings suggest that the interaction of CD4+,CD25+ Treg cells with activated monocytes in the joint might lead to diminished suppressive activity of CD4+,CD25+ Treg cells in vivo, thus contributing to the chronic inflammation in RA.
Musculoskeletal abnormalities of the tibia in juvenile rheumatoid arthritis
Authors: Felin Elena M. O. , Prahalad Sampath , Askew E. Wayne , Moyer‐Mileur Laurie J.
Published: February 2007

Objective

To characterize local bone geometry, density, and strength, using peripheral quantitative computed tomography (pQCT), compared with general bone characteristics as measured using dual x‐ray absorptiometry (DXA), and to assess their relationship to disease‐related factors in children with juvenile rheumatoid arthritis (JRA).

Methods

Forty‐eight children ages 4–18 years with JRA (17 pauciarticular, 23 polyarticular, 8 systemic) were compared with age‐matched healthy controls (n = 266). Measurements included cortical and trabecular bone geometry, density, and strength at the distal and midshaft tibia determined by pQCT, and whole‐body, lumbar spine, and femoral neck measurements by DXA.

Results

Methotrexate (MTX) was prescribed to 23 of 48 patients (47.9%) and glucocorticoids and MTX were prescribed to 15 of 48 patients (31.3%), with the greatest use in children with systemic JRA. All JRA patients had decreased tibia trabecular bone density, cortical bone size and strength, and muscle mass. Children with systemic JRA had lower femoral neck densities. Systemic JRA was associated with a shorter, less mineralized skeleton, while a narrower, less mineralized skeleton was observed in polyarticular JRA. The tibia diaphysis was narrower with decreased muscle mass, but normal, size‐adjusted bone mineral in all subtypes indicated a localized effect of JRA on bone. Patients exposed to glucocorticoids and MTX or to glucocorticoids or MTX alone had greatly reduced trabecular density, cortical bone geometry properties, and bone mineral content, muscle mass, and bone strength.

Conclusion

Children with JRA have decreased skeletal size, muscle mass, trabecular bone density, cortical bone geometry, and strength. Not surprisingly, these bone abnormalities are more pronounced in children with greater disease severity.