bluuebunny/crossref_metadata_2025 huggingface dataset:
T2*‐weighted magnetic resonance imaging with hyperoxia in acute ischemic stroke
Authors: Dani Krishna A. , Santosh Celestine , Brennan David , McCabe Christopher , Holmes William M. , Condon Barrie , Hadley Donald M. , Macrae I. Mhairi , Shaw Martin , Muir Keith W.
Published: March 2010

Objective

We describe the first clinical application of transient hyperoxia (“oxygen challenge”) during T2*‐weighted magnetic resonance imaging (MRI), to detect differences in vascular deoxyhemoglobin between tissue compartments following stroke.

Methods

Subjects with acute ischemic stroke were scanned with T2*‐weighted MRI and oxygen challenge. For regions defined as infarct core (diffusion‐weighted imaging lesion) and presumed penumbra (perfusion‐diffusion mismatch [threshold = Tmax ≥4 seconds], or regions exhibiting diffusion lesion expansion at day 3), T2*‐weighted signal intensity–time curves corresponding to the duration of oxygen challenge were generated. From these, the area under the curve, gradient of incline of the signal increase, time to maximum signal, and percentage signal change after oxygen challenge were measured.

Results

We identified 25 subjects with stroke lesions >1ml. Eighteen subjects with good quality T2*‐weighted signal intensity–time curves in the contralateral hemisphere were analyzed. Curves from the diffusion lesion had a smaller area under the curve, percentage signal change, and gradient of incline, and longer time to maximum signal (p < 0.05, n = 17) compared to normal tissue, which consistently showed signal increase during oxygen challenge. Curves in the presumed penumbral regions (n = 8) showed varied morphology, but at hyperacute time points (<8 hours) showed a tendency to greater percentage signal change.

Interpretation

Differences in T2*‐weighted signal intensity–time curves during oxygen challenge in brain regions with different pathophysiological states after stroke are likely to reflect differences in deoxyhemoglobin concentration, and therefore differences in metabolic activity. Despite its underlying complexities, this technique offers a possible novel mode of metabolic imaging in acute stroke. ANN NEUROL 2010;68:37–47
Synthesis and property measurements of polyimides with substituted pyromellitic dianhydride for flexible printed circuits applications
Authors: Choi J. K. , Yoon T. H.
Published: March 2010

Pyromellitic dianhydride‐based dianhydrides with bulky substituents, such as 1‐phenyl pyromellitic dianhydride and 1‐(4′‐trifluoromethylphenyl)pyromellitic dianhydride, were combined with bis(3‐aminophenyl)phenylphosphine oxide and 4,4′‐phenylene diamine to prepare polyimides with low coefficient of thermal expansion (∼ 17 ppm/°C) and good adhesion (>100 g/mm). The polyimides were synthesized via a conventional two‐step process: preparation of poly(amic‐acid) followed by solution imidization with o‐dichlorobenzene. The molecular weights of the polyimides were controlled to 25,000 g/mol via off‐stoichiometry and the synthesized polyimides were characterized by Fourier transform infrared, nuclear magnetic resonance, differential scanning calorimetry, and thermogravimetric analysis. Their intrinsic viscosity and solubility were also measured, while adhesive property was measured via T‐peel test samples of Cu/polyimide. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Numerical investigation of the effect of screw geometry on the mixing of a viscous polymer melt
Authors: Wang C. , Bussmann M. , Park C. B.
Published: March 2010

In polymer extrusion processing, mixing enhancement is an important consideration when an extruder screw is being designed. There are a variety of mixing elements used in the extrusion industry, with little consensus about what differentiates a good mixing section from a poor one. However, good mixing is important for homogenizing the material structure and temperature profile in the flow channel. This article presents a numerical analysis of the role of screw geometry in mixing in a cooling extruder. Four geometries, typical of those used by the extrusion industry, are assessed by the study of the polymer melt flow and heat transfer in the screw channels. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Direct low‐potential electropolymerization of 9,10‐dihydrophenanthrene in boron trifluoride diethyl etherate
Authors: Nie Guangming , Zhou Liangjie , Zhang Yan , Xu Jingkun
Published: March 2010

High‐quality poly(9,10‐dihydrophenanthrene) (PPh) with good fluorescence properties was synthesized electrochemically by the direct anodic oxidation of 9,10‐dihydrophenanthrene in boron trifluoride diethyl etherate (BFEE). PPh films obtained from BFEE‐based electrolytes showed good electrochemical behavior and good thermal stability with an electrical conductivity of 2.2 × 10−3 S/cm; this indicated that BFEE was a better medium for the electrosyntheses of PPh films. Dedoped PPh films were soluble in CH2Cl2, dimethylformamide, and dimethyl sulfoxide. The structure and morphology of the polymer were also characterized by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, 1H‐NMR spectroscopy, and scanning electron microscopy, respectively, which indicated the polymerization mainly occurred at the C(2) and C(7) positions. Fluorescent spectral studies indicated that PPh was a good blue‐light emitter. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Solution and quasi‐bulk copolymerizations of styrene and methyl methacrylate in the presence of polybutadiene: Mathematical model
Authors: Gutierrez Carolina , Estenoz Diana A. , Gugliotta Luis M. , Vega Jorge R. , Meira Gregorio R.
Published: March 2010

A mathematical model was developed for simulating the batch copolymerization of styrene (St) and methyl methacrylate (MMA) in the presence of polybutadiene (PB). It was adjusted to the measurements of three reactions carried out at 65°C, with initial comonomers ratio at the azeotropic condition, THF as solvent, and benzoyl peroxide as initiator. The measurements included: (a) conversions and grafting efficiencies by gravimetry; (b) molecular weight distributions (MWDs) by size exclusion chromatography; and (c) global mass fractions of St in the co‐ and terpolymer, by UV‐Vis spectroscopy. The model predicts the MWDs of the three polymeric components of MBS: free St‐MMA copolymer, St‐MMA‐g‐PB graft terpolymer (GT), and residual PB. In addition, it predicts the bivariate chain length distributions of the different GT topologies, with each topology characterized by the number of branches per molecule. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The effect of trimethylol propane tetraacrylate (TMPTA) and organoclay loading on the properties of electron beam irradiated ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay nanocomposites
Authors: Ismail Hanafi , Munusamy Yamuna , Mariatti M. , Ratnam Chantara Thevy
Published: March 2010

Ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay nanocomposites were prepared by melt blending technique with 0–10 phr organoclay loading and 3 phr TMPTA. Electron beam initiated crosslinking on these samples was carried out using a 3.0 MeV electron beam machine with doses ranging from 50 to 200 kGy. XRD results proved that dispersion of organoclay in the nanocomposites was slightly improved by irradiation with TMPTA. This was further supported by transmission electron microscopy images, where the nanoscale dispersion of organoclay was more homogenous throughout the irradiated polymer matrix compared to nonirradiated samples. TMPTA also increased the gel fraction yield, tensile properties and thermal stability of the irradiated neat EVA/SMR L and its nanocomposites. TMPTA was found to act as a crosslink initiator, which promotes crosslink bridges via free radical mechanism in EVA/SMR L matrix. SEM observation shows that the fracture behavior of the irradiated neat EVA/SMR L and its nanocomposites with TMPTA is significantly different compared to the fracture behavior of the nonirradiated neat EVA/SMR L. The distinct failure surface structure formed in the irradiated samples with TMPTA explains the overall higher value of tensile properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Influence of finish treatment on the durability of aramid fibers aged under an alkaline environment
Authors: Derombise Guillaume , Vouyovitch Van Schoors Laëtitia , Messou Marie‐Fleur , Davies Peter
Published: March 2010

Aramid fibers are high‐performance materials which have been used in ropes and protective clothing for many years. They are also now being proposed in geotextiles for ground reinforcement. The influence of the surface finish composition and content has been studied in the field of cables and textiles, but there is no published data concerning the effect of a finish treatment on the hydrolytic degradation. Aramid fibers with different finish contents have been aged in an alkaline environment. The degradation has been identified by FTIR, viscosimetry, TGA, SEM, and tensile tests. For Technora fibers, the presence of finish appears to limit the tensile strength loss of aramid fibers at pH 11 by limiting abrasion, as well as bulk and surface degradation. For Twaron fibers, higher finish content only has a slight influence on the fibers durability at pH 11 and pH 9, by limiting abrasion and bulk degradation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
A study toward the physicochemical properties of graft copolymer (partially carboxymethylated guar gum‐g‐N,N′‐dimethylacrylamide): Synthesis and characterization
Authors: Yadav Mithilesh , Sand Arpit , Kumar Mishra Dinesh , Behari Kunj
Published: March 2010

Unreported graft copolymer of N,N′‐dimethylacrylamide (DMA) with partially carboxymethylated guar gum (CmgOH) has been synthesized and the reaction conditions have been optimized for affording maximum grafting using a potassium peroxymonosulphate (PMS)/thiourea (TU) redox initiators under nitrogen atmosphere. The study of graft copolymerization has been performed to observe maximum value of grafting parameters except percentage of homopolymer by varying the concentrations of DMA, PMS, and TU. The grafting parameters increase continuously on increasing the concentration of DMA from 8 × 10−2 to 24 × 10−2 mol dm−3, PMS from 5 × 10−3 to 21 × 10−3 mol dm−3, and TU from 1.6 × 10−3 to 4.8 × 10−3 mol dm−3. The optimum temperature and time for grafting of DMA onto CmgOH were found to be 35°C and 120 min, respectively. The water‐swelling capacity of graft copolymer is investigated. Flocculation property for both coking and noncoking coals is studied for the treatment of coal mine waste water. The graft copolymer is characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Controlled radical polymerization of N‐vinylphthalimide using carboxyl‐terminated trithiocarbonate as RAFT agent and preparation of microfibers via electrospinning technique
Authors: Chikhaoui‐Grioune D. , Aqil A. , Zalfen A. M. , Benaboura A. , Jérome C.
Published: March 2010

Reversible addition‐fragmentation chain transfer (RAFT) polymerization of N‐vinylphthalimide in N,N‐dimethylformamide (DMF) solution was carried out using 2‐carboxypropan‐2‐yl dodecyl trithiocarbonate as a reversible chain transfer agent in the presence of 2,2′‐azobisisobutyronitrile. The molecular weights of the polymers increased linearly with the monomer conversion and the molecular weight distributions were relatively narrow (PDI < 1.2). It is confirmed by chain extension reaction that the polymer prepared via RAFT polymerization can be used as a macro‐RAFT agent. The structure of both polymers was characterized and confirmed by size‐exclusion chromatography and 1H‐NMR techniques. Ultrafine microfibers were prepared by electrospinning of poly(N‐vinylphthalimide) in DMF solution. The effects of electrospinning process parameters such as voltage, tip‐to‐collector distance, and solution concentration on the morphology and the average size of the electrospun fibers were studied. To evaluate the fiber diameters, scanning electron microscope micrographs of the microfibers were performed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Pongamia glabra seed oil based poly(urethane–fatty amide)
Authors: Kashif Mohammad , Zafar Fahmina , Ahmad S.
Published: March 2010

Poly(urethane–fatty amide) (PUPGFA) was developed to use nonedible and nondrying Pongamia glabra seed oil. The resin was synthesized by the reaction of N,N‐bis(2‐hydroxyethyl) P. glabra fatty amide (HEPGFA) and tolylene‐2,4‐diisocyanate through a one‐shot technique with a minimal amount (8–10%) of organic solvent. The structural elucidation of the resin was carried out by Fourier transform infrared (FTIR), 1H‐NMR, and 13C‐NMR spectroscopic techniques, whereas the curing mechanism was confirmed by FTIR spectroscopy and differential scanning calorimetry. The solubility of the resin was studied in different polar and nonpolar solvents. Thermal analysis was carried out by thermogravimetric analysis and differential thermal analysis techniques. Antibacterial studies of HEPGFA and PUPGFA were performed in the presence of Gram‐negative Salmonella and Gram‐positive Staphylococcus aureus bacteria by an agar diffusion method. Physicochemical, physicomechanical, and corrosion‐resistance tests were performed by standard laboratory methods. PUPGFA had good physicomechanical properties, excellent chemical/corrosion resistance, and moderate antibacterial activities. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Comparison between crosslink densities derived from stress–strain data and theoretically data evaluated through the α‐model approach for a polyurethane network system based on hydroxyl terminated polybutadiene and isophorone‐diisocyanate
Authors: Sekkar V.
Published: March 2010

The crosslink density (CLD) for polyurethane elastomeric networks based on hydroxyl terminated polybutadiene and isophorone‐diisocyanate was theoretically calculated with α‐model equations the employing the functionality distribution and extent of reaction as input parameters. The theoretical crosslink density (νt) was compared with the CLD values computed from stress–strain data evaluated at various strain rates. The methods for the calculation of the CLD from stress–strain data were based on the Mooney–Rivlin and Young's modulus approaches. Theoretical stress–strain curves were generated on the basis of νt conforming to both phantom and affine model calculations. The experimental stress–strain plots aligned more closely to the affine model line. The deviation of the experimentally derived stress–strain curves from the theoretical affine curve was probably due to the presence of temporarily trapped physical entanglements. From the stress–strain data, the concentrations of true chemical crosslinks and physical entanglements were estimated individually. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
In situ SEM study of fatigue crack growth mechanism in carbon black‐filled natural rubber
Authors: Beurrot Stéphanie , Huneau Bertrand , Verron Erwan
Published: March 2010

A micro‐tensile testing machine placed in the chamber of a scanning electron microscope is used to perform in situ fatigue tests on a 43 phr carbon black‐filled cis‐1,4‐polyisoprene rubber; the crack tip is observed in real‐time during crack propagation. These observations lead to a detailed description of the crack tip morphology; the crack front is a regular pattern of diamond‐shaped zones delimited by extended straight ligaments. Fatigue crack growth is driven by the ligaments breakage, which occurs in all the zones of the crack front surface continuously in time but at different velocities. This phenomenon of nonlocalized damage explains initiation and limited propagation of branches which deviate from the main crack. All those mechanisms are sources of energy dissipation which explains the great fatigue properties of NR. Finally, from similar experiments conducted on styrene butadiene rubber, it is established that the peculiar morphology of the crack tip and mechanism of crack propagation in NR are due to strain‐induced crystallization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Nonisothermal crystallization kinetics of isotactic polypropylene containing nucleating agent and dispersant
Authors: Qin Jun , Chen Xiaolang , Yu Jie , Wang Yang , Tian Yaozhu , Wu Song
Published: March 2010

In this article, nonisothermal crystallization kinetics was investigated by using differential scanning calorimeter. The Avrami, Ozawa, and combined Avrami with Ozawa (Mo method) equations were applied to describe the crystallization kinetics and estimate the kinetic parameters of mathematical models under the nonisothermal crystallization of isotactic polypropylene (iPP) with rosin nucleating agent (RNA) and calcium stearate as dispersant (CSD). The results show that RNA can improve the crystallization temperature and accelerate the nucleation rate because of its heterogeneous nucleation. The crystal grain sizes of spherulites are smaller for iPP with RNA and CSD together than those for pure iPP and its matrix only filled with RNA. Furthermore, iPP blends with RNA and CSD show a lower Avrami values than that of the pure iPP, and the Mo method can successfully describe the crystallization model under the nonisothermal crystallization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Water absorption pattern and dimensional stability of oil palm fiber–linear low density polyethylene composites
Authors: Shinoj S. , Panigrahi S. , Visvanathan R.
Published: March 2010

The water absorption pattern and associated dimensional changes and solid loss of oil palm fiber–linear low density polyethylene composites was studied. The effects of fiber size (425–840, 177–425, and 75–177 μ), fiber loading (0, 10, 20, 30, 40, and 50%), and time of immersion (192 h at an interval of 24 h) on these parameters were also studied. Alkali treatment of fibers was done to reduce the hydrophilic nature of the composites and its effect was studied. It was found that the water absorption in most of the combinations followed typical Fickian behavior. The rate of water absorption and swelling increased with fiber loading. However, alkali treatment of the fibers resulted in a reduction of water absorption at higher fiber loadings only, and composites with higher fiber sizes exhibited higher water absorption. A sharp increase in the thickness swelling was observed in the initial days of immersion, which remained constant thereafter. The thickness swelling also increased with fiber size; however, a constant trend was not observed for the 75–177 μ fiber size. In addition to thickness swelling, composites also expanded linearly during water absorption; however, linear expansion was considerably less than thickness swelling. Higher fiber loading and alkali treatment caused more linear expansion. We observed that maximum solid loss on water immersion occurred with small‐sized and also alkali‐treated fiber composites. An increase in thickness and a decrease in linear dimension were observed after one sorption–desorption cycle. This irreversible change was also found to be proportional to fiber loading and alkali treatment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of linear asymmetrical poly(propylene oxide) diol
Authors: Yang Peng Fei , Zhu Xu Wei , Li Jun Ying , Xia Yong Mei , Li Tian Duo
Published: March 2010

Linear asymmetrical poly(propylene oxide) was synthesized through four‐step reactions: selective benzylation, alcohol exchange reaction, propylene oxide anionic polymerization, debenzylation. One terminal of the asymmetrical polymer chains is alcohol hydroxyl and the other is phenol hydroxyl. It was characterized with infrared (IR) and 1H Nuclear Magnetic Resonance (1H‐NMR). Peaks at 1.11, 3.38, and 3.53 ppm were attributed to side groups (OCH2CH(CH3)), backbone units (OCH2CH(CH3)) and (OCH2CH(CH3)) of poly(propylene oxide), respectively. Molecular weight and molecular weight distribution were measured with 1H‐NMR and laser light scattering (LLS), which showed that the linear asymmetrical poly(propylene oxide) was mono‐disperse (PDI = 1.02–1.07). Then, its carbamate reaction with phenyl isocyanate was studied; the reaction rate constants for phenol hydroxyl and alcohol hydroxyl of poly(propylene oxide) were k1 = 0.209 mol L−1 min−1 and k2 = 0.051 mol L−1 min−1. There was a great reactivity difference for two types of hydroxyls in asymmetrical poly(propylene oxide), contrasting to the single carbamate reaction rate constant of symmetrical poly(propylene oxide) (k3 = 0.049 mol L−1 min−1). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Friendly to environment heterocyclic adducts as corrosion inhibitors for steel in water‐borne paints
Authors: Mohamed H. A. , Farag A. A. , Badran B. M.
Published: March 2010

Two groups of emulsion paints were formulated to evaluate the efficiency of emulsified heterocyclic adducts: 2‐mercaptothiazoline (2‐MT), 2‐mercaptobenzothiazole (2‐MBT), 2‐mercapto‐5‐methyl‐1,3,4‐thiadiazole (2‐MMT), and 3‐mercapto‐4‐methyl‐4H‐1,2,4‐triazole (3‐MMT). Different concentrations of 2‐MT adduct, which has the simplest structure were added in water‐borne paint formulations based on urabrid AC 100 emulsion resin to detect the optimum concentration range of the adduct as corrosion inhibitor. The efficiency of all the emulsified adducts has been studied at constant concentration within the optimum range in order to arrange them according to their efficiency as corrosion inhibitor for mild steel. Chemical, mechanical, corrosion resistance and water up‐take tests of paint films were measured. Weight loss measurements (mg/cm2), for steel panels under paint films and the steel corrosion inhibition efficiency of adduct has been determined. It was found that the prepared water‐borne adducts could protect steel from corrosion and their efficiencies as corrosion inhibitors could be arranged in descending order: 3‐MMT > 2‐MMT > 2‐MBT > 2‐MT adducts. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Gamma radiation synthesis and swelling properties of hydrogels based on poly(ethylene glycol)/methacrylic acid (MAc) mixtures
Authors: El‐Din Horia M. Nizam , El‐Naggar Abdel Wahab M.
Published: March 2010

In this work, gamma radiation was used to prepare hydrophilic hydrogels based on different mass ratios of poly(ethylene glycol) (PEG) and methacrylic acid (MAc) monomer. The thermal stability of hydrogels was characterized thermogravimetric analysis (TGA). The effect of temperature and pH, as external environments, on the equilibrium swelling of PEG/MAc hydrogels was also studied. The results showed that the gel fraction of PEG/MAc hydrogels is lower than that of PMAc hydrogel, in which the gel fraction of PMAc hydrogel was decreased greatly with increasing the mass ratio of PEG polymer in the initial solutions. The results showed that PEG/MAc hydrogels reached the equilibrium swelling state in water after 6 hours. It was found that the equilibrium swelling of PEG/MAc hydrogels displayed a transition change within the temperature range 30–40°C. This change in equilibrium swelling was illustrated by differential scanning calorimetry (DSC). However, it was observed that the equilibrium swelling of PEG/MAc hydrogels increases progressively with increasing the pH value from 4 up to 8. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and properties of organosoluble polyimides derived from 2,2′‐dibromo‐ and 2,2′,6,6′‐tetrabromo‐4,4′‐oxydianilines
Authors: Chen Jyh‐Chien , Liu Yuan‐Tsai , Leu Chyi‐Ming , Liao Hsueh‐Yi , Lee Wen‐Chin , Lee Tzong‐Ming
Published: March 2010

Two new aromatic diamines, 2,2′‐dibromo‐4,4′‐oxydianiline (DB‐ODA 4) and 2,2′,6,6′‐tetrabromo‐4,4′‐oxydianiline (TB‐ODA 5), have been synthesized by oxidation, bromination, and reduction of 4,4′‐oxydianiline (4,4′‐ODA). Novel polyimides 6a–f and 7a–f were prepared by reacting DB‐ODA (4) and TB‐ODA (5) with several dianhydrides by one‐step method, respectively. The inherent viscosities of these polyimides ranged from 0.31 to 0.99 dL/g (0.5 g/dL, in NMP at 30°C). These polyimides showed enhanced solubilities compared to those derived from 4,4′‐oxydianiline and corresponding dianhydrides. Especially, polyimides 7a, derived from rigid PMDA and TB‐ODA (5) can also be soluble in THF, DMF, DMAc, DMSO, and NMP. These polyimides also exhibited good thermal stability. Their glass transition temperatures measured by thermal mechanical analysis (TMA) ranged from 251 to 328°C. When the same dianhydrides were used, polyimides 7 containing four bromide substituents had higher glass transition temperatures than polyimides 6 containing two bromide substituents. The effects of incorporating more polarizable bromides on the refractive indices of polyimides were also investigated. The average refractive indices (nav) measured at 633 nm were from 1.6088 to 1.7072, and the in‐plane/out‐of‐plane birefringences (Δn) were from 0.0098 to 0.0445. It was found that the refractive indices are slightly higher when polyimides contain more bromides. However, this effect is not very obvious. It might be due to loose chain packing resulted from bromide substituents at the 2,2′ and 2,2′,6,6′ positions of the oxydiphenylene moieties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of an amphiphilic hyperbranched poly(amine‐ester)‐co‐D,L‐lactide (HPAE‐co‐PLA) copolymers and their nanoparticles for protein drug delivery
Authors: Jiang Ming , Wu Yan , He Yong , Nie Jun
Published: March 2010

A series of hyperbranched poly(amine‐ester)‐co‐D,L‐lactide (HPAE‐co‐PLA) copolymer were synthesized by ring‐opening polymerization of D,L‐lactide with Sn(Oct)2 as catalyst to a fourth generation branched poly(amine‐ester) (HPAE‐OHs4). The chemical structures of copolymers were determined by FTIR, 1H‐NMR, 13C‐NMR, and TGA. Double emulsion (DE) and nanoprecipitation (NP) method were used to fabricate the nanoparticles of these copolymers encapsulating bovine serum albumin (BSA) as a model. DSC thermo‐grams indicated that the nanoparticles with BSA kept stable below 40°C. Different factors which influence on particular size and encapsulation efficiency (EE) were investigated. Their EE to BSA could reach 97.8% at an available condition. In vitro release behavior of NPs showed a continuous release after a burst release. The stability maintenance of BSA in the nanoparticle release in vitro was also measured via circular dichroism and fluorescence spectrometry. The results showed that the copolymer nanoparticles have a promising potential in protein delivery system. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and properties of new thermally stable and optically active organosoluble poly(ether‐amide‐imide)s containing bicyclo segment in the main chain
Authors: Faghihi Khalil , Shabanian Meisam , Hajibeygi Mohsen , Mohammadi Yasser
Published: March 2010

N,N′‐(bicyclo[2,2,2]oct‐7‐ene‐tetracarboxylic)‐bis‐L‐amino acids 3a‐f were synthesized by the condensation reaction of bicyclo[2,2,2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride 1 with two equimolars of L‐alanine 2a, L‐valine 2b, L‐leucine 2c, L‐isoleucine 2d, L‐phenyl alanine 2e and L‐2‐aminobutyric acid 2f in an acetic acid solution. Also 1,4‐bis[4′‐nitrophenoxy]butane 6 was prepared by reaction of 4‐nitrophenol 4 with 1,4‐dibromo butane 5 in DMF solution. Then dinitro 6 was reduced to 1,4‐bis[4′‐aminophenoxy]butane 7 by using 10% Pd‐C, ethanol and hydrazine monohydrate. Then, six new poly(ether‐amide‐imide)s PEAIs 8a‐f were synthesized through the direct polycondensation reaction of six chiral N,N′‐(bicyclo[2,2,2]oct‐7‐ene‐tetracarboxylic)‐bis‐L‐amino acids 3a‐f with diamine 7 by direct polycondensation methods in a medium consisting of N‐methyl‐2‐pyrrolidone (NMP)/triphenyl phosphite (TPP)/calcium chloride (CaCl2)/pyridine (Py). The polymerization reaction produced a series of organsoluble and thermally stable poly (ether‐amide‐imide)s 8a‐f with high yield. The resulted polymers were fully characterized by means of FTIR, 1H‐NMR spectroscopy, elemental analyzes, inherent viscosity, specific rotation and solubility tests. Data obtained by thermal analysis (TGA and DTG) revealed that these polymers show good thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Controlled degradation of natural rubber and modification of the obtained telechelic oligoisoprenes: Preliminary study of their potentiality as polyurethane foam precursors
Authors: Saetung Anuwat , Rungvichaniwat Adisai , Campistron Irène , Klinpituksa Pairote , Laguerre Albert , Phinyocheep Pranee , Pilard Jean‐François
Published: March 2010

Telechelic oligoisoprenes were successfully prepared by the selective controlled degradation of natural rubber, a renewable source, via epoxidation and cleavage reactions. The molar mass of the oligoisoprene product obtained depends on the degree of epoxidation of the starting materials. The chemically modified structures obtained via epoxidation, hydrogenation, and ring opening of epoxide groups were also studied, and the chemical structures and thermal properties of the oligoisoprene products were determined. Moreover, the preliminary study of preparation of hydroxytelechelic natural rubber (HTNR)‐based polyurethane foam was performed. A novel HTNR‐based polyurethane foam was successfully prepared and its thermal properties were investigated and the results indicated that the HTNR‐based polyurethane foam has a good low temperature flexibility. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Precipitation of submicrometer‐sized poly(methyl methacrylate) particles with a compressed fluid antisolvent
Authors: Lin I‐Hsiang , Liang Pei‐Fang , Tan Chung‐Sung
Published: March 2010

Submicrometer‐sized poly(methyl methacrylate) (PMMA) particles were generated by precipitation with a compressed fluid antisolvent technique. The precipitation was carried out as follows. A solution containing PMMA was sprayed through a nozzle into a precipitator. The antisolvent CO2 was continuously passed through the precipitator during the operation at a flow rate of 2000 mL/min. When toluene was used as the solvent, scanning electron microscopy images showed that solid, spherical PMMA particles with less coalescence could be generated only when both vapor and liquid CO2 was present and the liquid CO2 level in the precipitator was one‐eighth. The morphology and size of the precipitated PMMA were found to be dependent on the solvents. Toluene, which had the lowest solubility parameter, was the most appropriate solvent in comparison with tetrahydrofuran, acetone, and nitromethane. More uniform submicrometer‐sized PMMA particles were obtained at PMMA concentrations equal to or less than 1.0 wt % in the toluene solution. A narrower particle size distribution was observed for precipitating PMMA with a molecular weight of 85,000 versus PMMA with a molecular weight of 36,000. To generate PMMA particles with less coalescence, liquid CO2 instead of supercritical CO2 was suggested for use in drying immediately after the spraying of the PMMA solution. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Randomized, prospective, placebo‐controlled trial of bosentan in interstitial lung disease secondary to systemic sclerosis
Authors: Seibold J. R. , Denton C. P. , Furst D. E. , Guillevin L. , Rubin L. J. , Wells A. , Matucci Cerinic M. , Riemekasten G. , Emery P. , Chadha‐Boreham H. , Charef P. , Roux S. , Black C. M.
Published: March 2010

Objective

Endothelin is implicated as a participatory pathway in systemic sclerosis (SSc). We tested this hypothesis in a 12‐month trial of bosentan, a nonselective endothelin receptor antagonist, as a therapy for SSc‐related interstitial lung disease (ILD).

Method

Patients with SSc and significant ILD were recruited to this prospective, double‐blind, randomized, placebo‐controlled, parallel group study. The inclusion criteria were designed to select a cohort enriched for patients with active and progressive disease. Exclusion factors included significant pulmonary hypertension. Patients with a diffusing capacity for carbon monoxide of <80% predicted and a 6‐minute walk distance of 150–500 meters or a 6‐minute walk distance of ≥500 meters with a decrease in oxygen saturation received bosentan or placebo. The primary efficacy end point was a change in the 6‐minute walk distance from baseline up to month 12. Secondary end points included time to death or worsening results of pulmonary function tests (PFTs). The safety and tolerability of bosentan were also assessed.

Results

Among the 163 patients, 77 were randomized to receive bosentan, and 86 were randomized to receive placebo. No significant difference between treatment groups was observed for change in the 6‐minute walk distance up to month 12. No deaths occurred in this study group. Forced vital capacity and diffusing capacity for carbon monoxide remained stable in the majority of patients in both groups. Significant worsening of PFT results occurred in 25.6% of patients receiving placebo and 22.5% of those receiving bosentan (P not significant).

Conclusion

No improvement in exercise capacity was observed in the bosentan‐treated group compared with the placebo group, and no significant treatment effect was observed for the other end points. Although many outcome variables were stable, bosentan did not reduce the frequency of clinically important worsening. These data do not support the use of endothelin receptor antagonists as therapy for ILD secondary to SSc.
Treg cell numbers and function in patients with antibiotic‐refractory or antibiotic‐responsive lyme arthritis
Authors: Shen Shiqian , Shin Junghee J. , Strle Klemen , McHugh Gail , Li Xin , Glickstein Lisa J. , Drouin Elise E. , Steere Allen C.
Published: March 2010

Objective

In a murine model of antibiotic‐refractory Lyme arthritis, the numbers of Treg cells are dramatically reduced. The aim of this study was to examine Treg cell numbers and function in patients with antibiotic‐refractory Lyme arthritis.

Methods

CD4+ T cell subsets were enumerated in the peripheral blood (PB) and synovial fluid (SF) of 12 patients with antibiotic‐refractory arthritis and 6 patients with antibiotic‐responsive arthritis. Treg cell function was examined using Borrelia‐specific and nonspecific Treg cell proliferation assays.

Results

In both patient groups, interferon‐γ–positive Th1 cells in SF were abundant and enriched (∼50% of CD4+ T cells). In patients with antibiotic‐refractory arthritis, the median percentages of FoxP3‐positive Treg cells were significantly higher in SF than in PB (12% versus 6%; P = 0.03) or in SF from patients with antibiotic‐responsive arthritis (12% versus 5%; P = 0.04). Moreover, in the antibiotic‐refractory group, a higher percentage of Treg cells in SF correlated with a shorter duration until resolution of arthritis (r = −0.74, P = 0.006). In contrast, patients with fewer Treg cells had suboptimal responses to disease‐modifying antirheumatic drugs and a longer duration of arthritis after antibiotic treatment, and they often required synovectomies for arthritis resolution. In each group, Treg cells in SF dampened Borrelia burgdorferi–specific proliferative responses, and in 2 patients with antibiotic‐refractory arthritis, Treg cells were functional in nonspecific suppression assays.

Conclusion

Treg cells were functional in patients with antibiotic‐refractory arthritis, and in some patients, higher numbers of these cells in SF appeared to participate in arthritis resolution. However, as in the murine model, patients with antibiotic‐refractory arthritis and lower numbers of Treg cells seemed unable to achieve resolution of synovial inflammation.
Deficiency of CXCR2, but not other chemokine receptors, attenuates autoantibody‐mediated arthritis in a murine model
Authors: Jacobs Jonathan P. , Ortiz‐Lopez Adriana , Campbell James J. , Gerard Craig J. , Mathis Diane , Benoist Christophe
Published: March 2010

Objective

Chemokines coordinate leukocyte trafficking in homeostasis and during immune responses. Prior studies of their role in arthritis have used animal models with both an initial adaptive immune response and an inflammatory effector phase. We undertook analysis of chemokines and their receptors in the effector phase of arthritis using the K/BxN mouse serum–transfer model.

Methods

A time‐course microarray analysis of serum‐transferred arthritis was performed, examining ankle tissue, synovial fluid, and peripheral blood leukocytes. Up‐regulation of chemokines was confirmed by quantitative reverse transcriptase–polymerase chain reaction. The functional relevance of chemokine induction was assessed by transferring serum into mice deficient in CCR1–7, CCR9, CXCR2, CXCR3, CXCR5, CX3CR1, CCL2, or CCL3. Further mechanistic analysis of CXCR2 involved treatment of arthritic mice with a CXCR2 antagonist, bone marrow (BM) cell transfers with CXCR2+/− and CXCR2−/− donors and recipients, flow cytometry of synovial cells, and competition experiments measuring enrichment of CXCR2‐expressing neutrophils in arthritic joints of mice with mixed CXCR2+/+ and CXCR2−/− BM cells.

Results

Gene expression profiling revealed up‐regulation of the CXCR2 ligands CXCL1, CXCL2, and CXCL5 in the joint in parallel with disease activity. CXCR2−/− mice had attenuated disease relative to CXCR2+/− littermates, as did mice receiving the CXCR2 inhibitor, while deficiency of other chemokine receptors did not affect arthritis severity. CXCR2 was required only on hematopoietic cells and was widely expressed on synovial neutrophils. CXCR2‐expressing neutrophils were preferentially recruited to arthritic joints in the presence of CXCR2‐deficient neutrophils.

Conclusion

CXCR2 (but not other chemokine receptors) is critical for the development of autoantibody‐mediated arthritis, exhibiting a cell‐autonomous role in neutrophil recruitment to inflamed joints.
A unified theory of autism revisited: linkage evidence points to chromosome X using a high‐risk subset of AGRE families
Authors: Allen‐Brady Kristina , Cannon Dale , Robison Reid , McMahon William M. , Coon Hilary
Published: March 2010

Zhao et al. [2007] in their “Unified Theory of Autism” hypothesized that incidence of autism in males could be explained by essentially two types of family structures: majority of autism cases are from low‐risk autism families with de novo mutations, and a minority of cases are from high‐risk multiplex families, where risk to male offspring approximates 50% consistent with a dominant model and high penetrance. Using the Autism Genetic Resource Exchange (AGRE) data set, Zhao et al. identified 86 high‐risk families with likely dominant transmission. As genotype data are now available for many members of the AGRE resource, the objective of this manuscript was to determine if dominant linkage evidence for an autism predisposition gene exists in these 86 high‐risk families. HumanHap550K Illumina SNP data were available for 92% of 455 total family members in these 86 high‐risk families. We performed a linkage analysis using a pruned subset of markers where markers in high linkage disequilibrium were removed. We observed a single suggestive peak (maximum LOD 2.01, maximum HLOD 2.08) under a dominant model on chromosome Xp22.11‐p21.2 that encompasses the IL1RAPL1 gene. Mutations or deletions in IL1RAPL1 have been previously reported in three families with autism. In our study, 11 families contributed nominally (P<0.05, HLOD>0.588) to the chromosome X peak. These results demonstrate that identification of a more homogeneous subset of autism cases, which was based on family structure in this study, may help to identify, localize and further our understanding of autism predisposition genes.
Septo‐optic dysplasia and associations with amyoplasia and gastroschisis
Authors: Kamien Benjamin , Zankl Andreas , Gabbett Michael
Published: March 2010

BACKGROUND:

The causes of septo‐optic dysplasia, amyoplasia, and gastroschisis are mostly unknown.

CASES:

We present a patient with septo‐optic dysplasia and amyoplasia. We also present a patient with features of septo‐optic dysplasia, gray matter heterotopias, and gastroschisis.

CONCLUSIONS:

These previously unreported combinations provide further support for vascular disruption in embryonic or fetal life as an etiological factor in these conditions. Birth Defects Research (Part A) 2010. © 2010 Wiley‐Liss, Inc.
BioEssays 4/2010
Authors: Lane Nick , Allen John F. , Martin William
Published: March 2010

Cover Photograph: The recipe for primordial soup: acid or bitter, hot or warm. JBS Haldane's concept of life arising from a “primordial soup” in a bowl riven by lightning still appeals to cartoonists making dinosaur movies, but it's scientifi‐cally moldy after 80 years. Studies on the origin of life are increasingly providing knowledge of the basic components that would be necessary to build artificial “living” systems, hence connecting a field of fundamental research that is frequently assumed to have no application with imminent technological developments. (see article: How did LUCA make a living? Chemiosmosis in the origin of life by: Nick Lane, John F. Allen and William Martin, http://dx.doi.org/10.1002/bies.200900131, in this issue). The image shows “The elementary particles of life ‐ energy generating proteins in the mitochondrial membranes” by Ina Schuppe‐Koistinen.
Real‐time PCR‐based determination of gene copy numbers in Pichia pastoris
Authors: Abad Sandra , Kitz Kerstin , Hörmann Astrid , Schreiner Ulrike , Hartner Franz S. , Glieder Anton
Published: March 2010

Pichia pastoris is a preferred host for heterologous protein production. Expression cassettes are usually integrated into the genome of this methylotrophic yeast. This manuscript describes a method for fast and reliable gene copy number determinations for P. pastoris expression strains. We believe that gene copy number determinations are important for all researchers working with P. pastoris and also many other research groups using similar gene integration techniques for the transformation of other yeasts. The described method uses real‐time PCR to quantify the integrated expression cassettes. Similar methods were employed previously for other host systems such as animal and plant cells but no such method comparing different detection methods and describing details for yeast analysis by quantitative PCR is known to us, especially for methylotrophic yeasts such as P. pastoris. Neglecting gene copy numbers can easily lead to false interpretations of experimental results from codon optimization or promoter studies and co‐expression of helper proteins as demonstrated in an application example, which is also described here.
Immobilization conditions of ketoreductase on enantioselective reduction in a gas‐solid bioreactor
Authors: Nagayama Kazuhito , Spiess Antje C. , Büchs Jochen
Published: March 2010

The immobilization conditions of commercial ketoreductase for continuous enantioselective reduction in the gas‐phase reaction were investigated with respect to the immobilization efficiency (residual activity and protein loading) and the gas‐phase reaction efficiency (initial reaction rate, half‐life, and enantioselectivity). For the analyses, ketoreductase was first immobilized by physical deposition on glass supports and the reduction of 2‐butanone to (S)‐2‐butanol with the concomitant regeneration of NADH by 2‐propanol was used as a model reaction. The optimal conditions of enzyme immobilization were obtained using an absolute pressure of 100 hPa for drying, a pH between 6.5 and 7.0, and a buffer concentration of 50 mM. The buffer concentration in particular had a strong effect on both the enzyme activity and enantioselectivity. Under optimal immobilization conditions, the thermostability of ketoreductase in the gas‐phase system was enhanced compared to the aqueous‐phase system, while the enantioselectivity was successfully maintained at a level identical to that of the native enzyme. These results indicate that the gas‐phase reaction has a great potential for industrial production of chiral compounds, but requires careful optimization of immobilization conditions for the reaction to progress effectively.
Virus susceptibility of Chinese hamster ovary (CHO) cells and detection of viral contaminations by adventitious agent testing
Authors: Berting Andreas , Farcet Maria R. , Kreil Thomas R.
Published: March 2010

Biopharmaceuticals are of increasing importance in the treatment of a variety of diseases. A remaining concern associated with their production is the potential introduction of adventitious agents into their manufacturing process, which may compromise the pathogen safety of a product and potentially cause stock‐out situations for important medical supplies. To ensure the safety of biological therapeutics, regulatory guidance requires adventitious agent testing (AAT) of the bulk harvest. AAT is a deliberately promiscuous assay procedure which has been developed to indicate, ideally, the presence of any viral contaminant. One of the most important cell lines used in the production of biopharmaceuticals is Chinese hamster ovary (CHO) cells and while viral infections of CHO cells have occurred, a systematic screen of their virus susceptibility has never been published. We investigated the susceptibility of CHO cells to infection by 14 different viruses, including members of 12 families and representatives or the very species that were implicated in previously reported production cell infections. Based on our results, four different infection outcomes were distinguished, based on the possible combinations of the two factors (i) the induction, or not, of a cytopathic effect and (ii) the ability, or not, to replicate in CHO cells. Our results demonstrate that the current AAT is effective for the detection of viruses which are able to replicate in CHO cells. Due to the restricted virus susceptibility of CHO cells and the routine AAT of bulk harvests, our results provide re‐assurance for the very high safety margins of CHO cell‐derived biopharmaceuticals. Biotechnol. Bioeng. 2010;106: 598–607. © 2010 Wiley Periodicals, Inc.
Implementation of communication‐mediating domains for non‐ribosomal peptide production in Saccharomyces cerevisiae
Authors: Siewers Verena , San‐Bento Rita , Nielsen Jens
Published: March 2010

Saccharomyces cerevisiae has in several cases been proven to be a suitable host for the production of natural products and was recently exploited for the production of non‐ribosomal peptides. Synthesis of non‐ribosomal peptides (NRPs) is mediated by NRP synthetases (NRPSs), modular enzymes, which are often organized in enzyme complexes. In these complexes, partner NRPSs interact via communication‐mediating domains (COM domains). In order to test whether functional interaction between separate NRPS modules is possible in yeast we constructed a yeast strain expressing two modules with compatible COM domains from two plasmids. Successful production as well as secretion of the expected dipeptide was detected. This opens the possibility of using yeast as a eukaryotic platform for fast assessment of new module combinations for the development of novel NRP compounds. Biotechnol. Bioeng. 2010;106: 841–844. © 2010 Wiley Periodicals, Inc.