bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure, mechanical, and fracture properties of nanoreinforced and HNBR‐toughened polyamide‐6
Authors: Siengchin Suchart , Karger‐Kocsis József
Published: August 2011

Hydrogenated nitrile rubber (HNBR) and synthetic nanofillers, viz. water‐swellable sodium fluorohectorite (FH) and water dispersible boehmite alumina (BA), were used to toughen and reinforce polyamide‐6 (PA‐6). FH and BA were introduced in HNBR latex that was dried prior to melt mixing with PA‐6. Binary blend (PA‐6/HNBR) and ternary nanocomposites (PA‐6/HNBR/nanofiller) were produced and their structure–property relationships studied. HNBR was coarsely and microscale dispersed in PA‐6. FH, slightly intercalated, was present in PA‐6 and in the PA‐6/HNBR interphase, whereas BA was mostly located in the HNBR droplets. HNBR improved the ductility of the PA‐6/HNBR blend at cost of stiffness and strength. The fracture toughness and energy, determined on notched Charpy specimens at different temperatures (T = −30°C, room temperature, and T = 80°C) were improved by blending with HNBR at 9 wt %. Additional incorporation of the nanofillers in 2.5 wt % enhanced the stiffness and strength of the PA‐6/HNBR blend but reduced its ductility. The fracture toughness of the ternary nanocomposites was between those of PA‐6 and PA‐6/HNBR, whereas their fracture energy fairly agreed with that of the parent PA‐6. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Study of chitosan and its derivatives as preservatives for field natural rubber latex
Authors: Loykulnant Surapich , Kongkaew Chaveewan , Chaikumpollert Oraphin , Sanguanthammarong Promsak , Na Ubol Preeyawis , Suchiva Krisda
Published: August 2011

In this study, the chitosan and its derivatives were tested for their preservative activities for field natural rubber (NR) latex. A series of chitosans with different molecular weights were obtained by nitrous acid depolymerization. The chemically modified chitosans, N‐carboxymethyl chitosan (NCMCh), N‐sulfated chitosan (NSCh), and N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (NHTACh), were prepared from high and low‐molecular weight chitosans. Preservative activities for field NR latex of these chitosans were investigated based on the measurement of volatile fatty acids (VFA) number of the treated latex. The preservative activities of chitosan increased with decreasing molecular weights. The low‐ molecular weight NSCh and NHTACh exhibited good preservative activity for the latex. By the use of low‐molecular weight NHTACh in combination with octylphenol poly (ethyleneglycolether) (Nonidet P40), the latex was successfully preserved for more than 1 month in the low‐ammonia condition. The results showed an attractive feature to develop the preservative system, which was possible to reduce the concentrations of ammonia and carcinogenic nitrosamine in the NR latex. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Conducting bicomponent fibers obtained by melt spinning of PA6 and polyolefins containing high amounts of carbonaceous fillers
Authors: Strååt Martin , Rigdahl Mikael , Hagström Bengt
Published: August 2011

Melt spinning of conductive polymer composites (CPCs) is coupled with some difficulties such as a decrease of conductivity upon drawing and a reduced spinnability with increasing filler concentration. Applying bicomponent technology may provide the possibility to produce fibers from CPCs with a high filler concentration. A pilot‐scale bicomponent melt spinning set‐up was used to produce core/sheath fibers with fiber titers between 13 and 47 dtex. The sheath material was polyamide 6 (PA6) or polypropylene (PP) and the core material was a CPC. Two CPCs were used, polypropylene (PP) with carbon black (CB), denoted by PP/CB, and polyethylene (PE) with multiwalled carbon nanotubes (MWNT), denoted by PE/MWNT. The results showed that both materials could be used with a filler concentration of 10 wt % to obtain melt draw ratios up to 195. The volumetric fraction of core material in the bicomponent structure was 28%. A heat treatment of PP/CB fibers restored the conductivity to the level of the undrawn material, corresponding to an increase in conductivity by a factor 5. The same heat treatment had a positive effect on the conductivity of PE/MWNT fibers although the conductivity was not restored. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Enhanced molecular orientation and strain hardening in melt‐spun isotactic polypropylene monofilaments through partial melting recrystallization
Authors: Li Zhujun , Na Bing , Tian Nana , Lv Ruihua , Zou Shufen
Published: August 2011

Achieving high molecular orientation, by increasing spinning velocity and/or postdrawing, is critical to improve the mechanical properties of isotactic polypropylene (iPP) fibers. In this study, we have demonstrated that upon annealing around melting point the molecular orientation of both amorphous and crystalline phases in melt‐spun iPP monofilaments is significantly enhanced, in parallel with the improved stability of crystals, because of partial melting and oriented recrystallization. As a result, high level stress and remarkable strain hardening are generated during stretching of annealed monofilaments. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Nanostructure and viscoelasticity of layered silicate nanocomposite–electrolyte supports
Authors: Cardoso Judith , Romo‐Uribe Angel , Flores Araceli
Published: August 2011

There is the need for novel polyelectrolytes with enhanced thermal and mechanical properties. In this report, we have reinforced a polyelectrolyte based on poly(dimethylaminoethylmethacrylate) (PDMAEM) using nanoclay montmorillonite (MMT), and have studied the thermal and viscoelastic properties. The protonated polymer (PDMAEMH) was solution mixed with functionalized MMT. Recognizing that the sort of surfactant may have a profound influence on the physical properties of the polymer matrix, neat MMT, and MMT treated with different surfactants (sulfobetaine and ammonia) were used, and the concentration of the nanofiller was varied from 1 to 5%w/w. Strikingly, while PDMAEM exhibited a glass transition temperature Tg of 32°C, the protonated PDMAEMH showed Tg = 155°C. Master curves obtained by applying the time‐temperature superposition principle showed that PDMAEM behaved predominantly elastic (G″ < G′) suggesting an entangled polymer melt. However, PDMAEMH exhibited much longer relaxation times, a shift of ca. seven decades in frequency, suggesting that ionic interactions significantly hampered the molecular dynamics. X‐ray scattering demonstrated that lower concentration and sulfobetaine surfactant favored exfoliation whereas ammonia and untreated MMT favored intercalation of the nanoplates. Furthermore, an enhancement in dynamic storage shear modulus was observed for the nanocomposites exhibiting intercalated morphologies relative to those displaying an exfoliated morphology. It is then suggested that the molecular dynamics is further slowed down due to confinement of the macromolecules between the nanoplates. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Properties and structure of MWNTs/cellulose composite fibers prepared by Lyocell process
Authors: Lu Jiang , Zhang Huihui , Jian Yihui , Shao Huili , Hu Xuechao
Published: August 2011

Lyocell fiber is a new kind of regenerated cellulose fiber and expected to replace the Rayon fiber to be not only used in the textile field but also used in the fields of industry and aerospace after being modified. In this work, the multi‐walled carbon nanotubes (MWNTs)/Lyocell composite fibers were prepared under different draw ratios by dry‐wet spinning and their electrical properties, mechanical properties, and structure were investigated. It was found that an appropriate amount of MWNTs could be dispersed homogeneously in the Lyocell matrix and could improve the mechanical and thermal properties of composite fiber. The results of wide angle X‐ray diffraction (WAXD) showed that the MWNTs in the composite fiber almost aligned along the axis of the fibers and the orientation of MWNTs increased with the increasing draw ratio. Furthermore, it was found that more MWNTs content and lower draw ratio could improve the electrical conductance of the composite fiber. The composite fiber containing 5 wt % MWNTs has a volume conductivity of 8.8 × 10−4 S/cm, which is five orders higher than that of pure Lyocell fiber. These results indicate that the MWNTs/Lyocell composite fiber has potential applications in the areas of precursor of carbon fiber and conductive fiber. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Nonisothermal degradation kinetics for epoxy resin systems containing polymethylphenylsilsesquioxane
Authors: Wang Jiangbo , Zhan Yeyong , Fang Jianghua , Gao Haoqi
Published: August 2011

The thermal degradation behaviors of polymethylphenylsilsesquioxane/epoxy resin (PMPSQ/EP) systems were investigated by thermogravimetric analysis (TGA) under nonisothermal conditions in nitrogen atmosphere. During nonisothermal degradation, Kissinger's and Flynn‐Wall‐Ozawa's methods were both used to analyze the thermal degradation process. The results showed that a remarkable increase of activation energy was observed in the presence of PMPSQ, which indicated that the addition of PMPSQ retarded the thermal degradation of EP. Flynn‐Wall‐Ozawa's method further revealed that PMPSQ significantly increased the activation energy of EP thermal degradation especially in the early and final stage of thermal degradation process, which illustrated that the PMPSQ stabilized the char layer and improved the flame retardancy of EP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Study on wettability improvement and its uniformity of wool fabric treated by atmospheric pressure plasma jet
Authors: Wang Chunxia , Qiu Yiping
Published: August 2011

The influence of processing parameters on wettability improvement and its uniformity of wool fabric treated by atmospheric pressure plasma jet (APPJ) was explored. A woven wool fabric was treated by APPJ under various treatment conditions such as different treatment time, different oxygen flow rate, and different jet‐to‐substrate distance. The water absorption time of wool fabric was measured to determine wettability improvement. The diffusion photo of water droplet on wool fabric surface was taken by digital camera to reflect wettability uniformity. After APPJ treatment, SEM observation showed that the scales on the wool fiber surface directly facing plasma jet pores were destroyed than those on the other fiber surface. XPS analysis showed that the carbon concentration substantially decreased. The concentration of oxygen and nitrogen significantly increased and but the concentration of sulfur and silicon did not obviously changed. With the addition of oxygen gas, more polar groups such as hydroxyl and carboxyl produced on wool fiber surface. The water absorption time of wool fabric greatly reduced indicating wettability improvement. The diffusion of water droplet on wool fabric surface was also larger and more homogenous suggesting uniform plasma treatment. It was concluded that the wettability improvement and its uniformity of the treated wool fabric increased and then decreased with the increasing oxygen flow rate and jet‐to‐substrate distance, and increased with the increasing treatment time. Therefore to achieve reasonable wettability and its uniformity of the wool fabric treated by APPJ, plasma treatment conditions have to be carefully chosen. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Self‐assembly of rod‐coil molecules into lateral chain‐length‐dependent supramolecular organization
Authors: Zhong Ke‐Li , Wang Qi , Chen Tie , Huang Zhegang , Yin Bingzhu , Jin Long Yi
Published: August 2011

In this article, we report synthesis and characterization of the self‐assembly behavior of coil‐ rod‐coil molecules, consisting of four biphenyls and a p‐terphenyl unit linked together with ether bonds as a rod segment. These molecules contain lateral methyl or ethoxymethyl groups at 2 and 5 positions of the middle benzene ring of p‐terphenyl. The self‐assembling behavior of these materials was investigated by means of DSC, POM, and SAXS in the bulk state. The results reveal that self‐assembling behavior of these molecules is dramatically influenced by a lateral methyl or ethoxymethyl groups in the middle of rod segment. In addition, molecule with PEO (DP = 17) coil chains of identical coil volume fraction to the corresponding molecule connected by PPO (DP = 12) coil chains, shows diverse self‐organizing behavior that may result from the parameters of cross‐sectional area of coil segment and the steric hindrance at the rod/coil interface. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Selective hydrogenation of nitrile‐butadiene rubber catalyzed by thermoregulated phase transfer phosphine rhodium complex
Authors: Ning Simin , Yang Shoufa , Wei Xinpeng , Wang Weimin , Zhang Liqun , Yue Dongmei
Published: August 2011

Hydrogenation of polymer having CC double bond can be carried out with the metal–organic complex as catalyst, which has the property of themoregulated phase transfer. In this study, a new complex RhCl[PPh[(OCH2CH2)5≤n≤6CH3]2]3 (Rh/AEOPP) was synthesized with a good yield, which was further used as catalyst to selectively hydrogenated nitrile‐butadiene rubber (HNBR). This is the first time that Rh/AEOPP complex was synthesized and applied in nitrile‐butadiene rubber (NBR) hydrogenation. The result shows that hydrogenation degree of product (HNBR) can be extended to 90%, when the condition is [Cat] = 3% (based the weight of NBR), L2: Cat (Weight Ratio) = 2, [NBR] = 5% (based on the weight of xylene solution), P (H2) = 1.5 MPa, T = 155°C, and t = 8 h. Also, by adjusting temperature, the catalyst could be easily separated from products with 89% catalyst complex recovery. In addition, 1H‐NMR and infrared (IR) spectra showed that CC double bonds in NBR was successfully hydrogenated without causing reduction of the CN group. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Processing‐dependent high impact polystyrene/styrene‐butadiene‐styrene tri‐block copolymer/carbon black antistatic composites
Authors: Tang Weihua , Liu Beibei , Liu Zhiwei , Tang Jian , Yuan Huilin
Published: August 2011

The electrical resistivity and morphology of high impact polystyrene (HIPS)/styrene‐butadiene‐styrene triblock copolymer (SBS)/carbon black (CB) blends were studied. Their antistatic sheets were prepared by both compression‐molding and extrusion calendaring process, with their surface morphology observed using scanning electron microscopy (SEM). The SEM images reveal better dispersion of CB achieved in extrusion‐calendering, resulting in low percolation threshold values in HIPS composites. Higher compression ratio and higher drawing speed (corresponding lower sheet thickness) are beneficial to get better CB dispersion, leading to decreased conductivity for the antistatic sheets. SEM images indicate that strong shear forces in extrusion tend to break the conductive network of CB, resulting in increased surface resistivity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Poly(dimethylsiloxane‐b‐styrene) diblock copolymers prepared by reversible addition‐fragmentation chain transfer polymerization: Kinetic model
Authors: Guan Cheng‐Mei , Luo Zheng‐Hong , Tang Pei‐Ping
Published: August 2011

Well‐defined polydimethylsiloxane‐block‐polystyrene (PDMS‐b‐PS) diblock copolymers were prepared by reversible addition‐fragmentation chain transfer (RAFT) polymerization using a functional PDMS‐macro RAFT agent. The RAFT polymerization kinetics was simulated by a mathematical model for the RAFT polymerization in a batch reactor based on the method of moments. The model described molecular weight, monomer conversion, and polydispersity index as a function of polymerization time. Good agreements in the polymerization kinetics were achieved for fitting the kinetic profiles with the developed model. In addition, the model was used to predict the effects of initiator concentration, chain transfer agent concentration, and monomer concentration on the RAFT polymerization kinetics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Morphology, dynamic mechanical, and electrical properties of bio‐based poly(trimethylene terephthalate) blends, part 2: Poly(trimethylene terephthalate)/poly(ether esteramide)/polycarbonate blends
Authors: Kobayashi Toshikazu , Wood Barbara A. , Takemura Akio
Published: August 2011

Bio‐based poly(trimethylene terephthalate) (PTT) and poly(ether esteramide) (PEEA) blends were prepared by melt processing with varying weight ratios (0–20 wt %) of polycarbonate (PC). The blends were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), polarized light microscopy (PLM), and transmission electron microscopy (TEM). Electrostatic performance was also investigated for those PTT blends since PEEA is known as an ion conductive polymer. DMA suggests that PC is miscible with PEEA and selectively goes into PEEA phase in case of ternary blends of PTT/PEEA/PC. The glass transition temperature (Tg) for PC/PEEA is well predicted by Gordon Taylor equation. Addition of PC retards the electrostatic decay performance of PTT/PEEA blends by restricting the motion of ions in PEEA through increasing the Tg of PEEA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Effect of the MMA content on the emulsion polymerization process and adhesive properties of poly(BA‐co‐MMA‐co‐AA) latexes
Authors: Xu Hongping , Wang Nongyue , Qu Taoguang , Yang Jianguang , Yao Yanmei , Qu Xiongwei , Lovell Peter A.
Published: August 2011

In the past work, the shear resistance of pure poly(n‐butyl acrylate) was low, even incorporation of inorganic filler, silica in the composition. It is well‐known that the copolymerization of n‐butyl acrylate (BA) with methyl methacrylate (MMA) will increase the glass transition temperature, and enhance the shear resistance of acrylic polymers. In the current work, the preparation of a series of acrylic water‐borne pressure‐sensitive adhesives (PSAs) with the controlled composition and structure for the copolymerization of BA and acrylic acid (AA) with different MMA contents, poly(BA‐co‐MMA‐co‐AA) was reported and its effects on adhesive properties of the latices were investigated. The latices of poly(BA‐co‐MMA‐co‐AA) were prepared at a solid content of 50% by two‐stage sequential emulsion polymerization, and this process consisted of a batch seed stage giving a particle diameter of 111 nm, which was then grown by the semicontinuous addition of monomers to final diameter of 303 nm. Dynamic light scattering (DLS) was used to monitor the particle diameters and proved that no new nucleation occurred during the growth stage. Copolymerization of BA with MMA raised the glass transition temperature (Tg) of the soft acrylic polymers, and had the effect of improving shear resistance, while the loop tack and peel adhesion kept relatively high. The relationship between pressure‐sensitive properties and molecular parameters, such as gel content and molecular weight, was evaluated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and properties of nano carboxylic acrylonitrile butadiene rubber latex toughened phenolic resin
Authors: Yu Zheng , Li Jingfeng , Yang Limin , Yao Yalin , Su Zhiqiang , Chen Xiaonong
Published: August 2011

Nano carboxylic acrylonitrile butadiene rubber latex‐toughened‐phenolic resins (XNBRL‐PF) were prepared by in situ polymerization in this work. The influence of nano XNBRL on the microstructure and physical properties of modified PF resin was investigated. Impact test testified that the impact strength of XNBRL‐PF was remarkably improved compared to pure PF and as the content of XNBRL increased to 10 wt %, the impact strength of the XNBRL‐PF kept increasing. Scanning electron microscope analysis of the fracture surface of the XNBRL‐PF indicated that the XNBRL were uniformly dispersed in the PF matrix, with diameters ranging from 200 to 400 nm. The results of Fourier transform infrared spectroscopy proved that chemical reaction occurred between XNBRL and PF matrix, which can greatly improve the interface interaction between rubber particles and PF matrix. Thermogravimetric analysis test showed that the incorporation of XNBRL can improve the thermostability of PF at low temperatures. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
A polycarbonate/magnesium oxide nanocomposite with high flame retardancy
Authors: Dong Quanxiao , Gao Chong , Ding Yanfen , Wang Feng , Wen Bin , Zhang Shimin , Wang Tongxin , Yang Mingshu
Published: August 2011

A new flame retardant polycarbonate/magnesium oxide (PC/MgO) nanocomposite, with high flame retardancy was developed by melt compounding. The effect of MgO to the flame retardancy, thermal property, and thermal degradation kinetics were investigated. Limited oxygen index (LOI) test revealed that a little amount of MgO (2 wt %) led to significant enhancement (LOI = 36.8) in flame retardancy. Thermogravimetric analysis results demonstrated that the onset temperature of degradation and temperature of maximum degradation rate decreased in both air and N2 atmosphere. Apparent activation energy was estimated via Flynn–Wall–Ozawa method. Three steps in the thermal degradation kinetics were observed after incorporation of MgO into the matrix and the additive raised activation energies of the composite in the full range except the initial stage. It was interpreted that the flame retardancy of PC was influenced by MgO through the following two aspects: on the one hand, MgO catalyzed the thermal‐oxidative degradation and accelerated a thermal protection/mass loss barrier at burning surface; on the other hand, the filler decreased activation energies in the initial step and improved thermal stability in the final period. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and thermal behavior of polymeric precursor for carbon‐free silicon oxynitride ceramic
Authors: Zhang Zongbo , Wang Rui , Wang Xiujun , Chen Li , Zhang Dahai , Luo Yongming , Xu Caihong
Published: August 2011

A new polymeric precursor, perhydropolysiloxazane (PSNO), for silicon oxynitride (SiON) ceramic was synthesized by a simple one‐pot procedure involving partial hydrolysis of H2SiCl2 and the following ammonolysis reaction of the hydrolyzed intermediates with NH3. The structure of new polymer was characterized with perhydropolysiloxane (PHSO) and perhydropolysilazane (PHSN) as reference substances. The conversion of PSNO to ceramic was investigated by TGA, FT‐IR, and solid 29Si‐NMR analyses. A Si‐rich Si2N2O ceramic was produced upon pyrolysis of PSNO at 1400°C under N2 atmosphere. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Thermal conductivity and dynamic mechanical property of glycidyl methacrylate‐grafted multiwalled carbon nanotube/epoxy composites
Authors: Teng Chih‐Chun , Ma Chen‐Chi M. , Yang Shin‐Yi , Chiou Kuo‐Chan , Lee Tzong‐Ming , Chiang Chin‐Lung
Published: August 2011

The well dispersed multiwalled carbon nanotube (MWCNT)/epoxy composites were prepared by functionalization of the MWCNT surfaces with glycidyl methacrylate (GMA). The morphology and thermal properties of the epoxy nanocomposites were investigated and compared with the surface characteristics of MWCNTs. GMA‐grafted MWCNTs improved the dispersion and interfacial adhesion in epoxy resin, and enhanced the network structure. The storage modulus of 3 phr GMA‐MWCNTs/epoxy composites at 50°C increased from 0.32 GPa to 2.87 GPa (enhanced by 799%) and the increased tanδ from 50.5°C to 61.7°C (increased by 11.2°C) comparing with neat epoxy resin, respectively. Furthermore, the thermal conductivity of 3 phr GMA‐MWCNTs/epoxy composite is increased by 183%, from 0.2042 W/mK (neat epoxy) to 0.5781 W/mK. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Fabrication of superhydrophobic fiber coatings by DC‐biased AC‐electrospinning
Authors: Ochanda Fredrick O. , Samaha Mohamed A. , Tafreshi Hooman Vahedi , Tepper Gary C. , Gad‐el‐Hak Mohamed
Published: August 2011

Mesh‐like fiber mats of polystyrene (PS) were deposited using DC‐biased AC‐electrospinning. Superhydrophobic surfaces with water contact angles greater than 150° and gas fraction values of up to 97% were obtained. Rheological study was conducted on these fiber surfaces and showed a decrease in shear stress when compared with a noncoated surface (no slip), making them excellent candidates for applications requiring the reduction of skin‐friction drag in submerged surfaces. We have also shown that addition of a second, low‐surface energy polymer to a solution of PS can be used to control the fiber internal porosity depending on the concentration of the second polymer. Contact‐angle measurements on mats consisting of porous and nonporous fibers have been used to evaluate the role of the larger spaces between the fibers and the pores on individual fibers on superhydrophobicity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Luminescent polydibenzothiophene thin film obtained by glow discharge method
Authors: Morales‐Corona Juan , López‐Barrera José A. , Avila‐Ortega Alejandro , Cruz Guillermo J. , Olayo María‐Guadalupe , Ortega‐López Mauricio , Vasquez‐Ortega Miguelina , Vazquez Humberto , Olayo Roberto
Published: August 2011

This work presents the synthesis by plasma and characterization of luminescent polymer thin films of dibenzothiophene (DBT) by plasma polymerization. The DBT is solid at room conditions and was sublimated and introduced to the plasma reactor to produce the chemical reactions with the vapors. The results indicated the production of polymers with benzene and thiophene rings in the structure as well as methylene groups. The polymer structure was studied by Fourier transform infrared spectroscopy and 13C‐CPMAS. The thermal analysis showed a residual mass of 60% at 800°C, which suggests a great thermal resilience in the polymer. The critical superficial tension was calculated with a Zisman plot and was 25 mN/m. The polymer has a fluorescent green emission between 400 and 660 nm and an orange emission between 660 and 850 nm. This effect can be a consequence of the electronic distribution along the structure in aliphatic and aromatic segments with benzene and thiophene rings. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
A simulation method to analyze chemo‐mechanical behavior of swelling‐induced shape‐memory polymer in response to solvent
Authors: Lu Haibao
Published: August 2011

A network of thermally responsive shape‐memory polymers (SMPs) could imbibe a quantity of solvent molecules to swell, and subsequently induces a chemical potential change in polymer. When an equilibrium is reached between the mechanical load and the chemical potential of polymer network and solvent, the SMP polymer usually swells with a field of inhomogeneous and anisotropic deformation, which is considered to be equivalent to a hyperelastic field. We implement this theory in the free‐energy function equation, and analyze examples of swelling‐induced deformation and shape recovery behavior. This work may provide a powerful tool to study complex swelling‐induced shape‐memory behavior of SMPs in response to the immersing solvents. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Tailoring the optical and thermomechanical properties of polymer host–guest systems
Authors: Hanemann Thomas , Honnef Kirsten
Published: August 2011

For modern applications in microoptics, the refractive index (n) of polymers can be adjusted in a certain range by the addition of electron‐rich organic dopants. As an unwanted side effect, a pronounced plasticizing occurs. In this work, the addition of a crosslinker (divinylbenzene) to an unsaturated polyester matrix, doped with phenanthrene for n adjustment, allowed us to successfully suppress the plasticizing effect measured after polymerization. Even at high phenanthrene concentrations, the glass‐transition temperature of the initial polymer could be almost retained. An increase of the polymer n from 1.5684 to a value of 1.6425 was achieved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Stable and high‐level production of recombinant Factor IX in human hepatic cell line
Authors: de Castilho Fernandes Andrielle , Fontes Aparecida , Gonsales Nathalia , Swiech Kamilla , Picanco‐Castro Virginia , Faca Sandra , Covas Dimas
Published: August 2011

Hemophilia B is a genetic disease of the coagulation system that affects one in 30,000 males worldwide. Recombinant human Factor IX (rhFIX) has been used for hemophilia B treatment, but the amount of active protein generated by these systems is inefficient, resulting in a high‐cost production of rhFIX. In this study, we developed an alternative for rhFIX production. We used a retrovirus system to obtain two recombinant cell lines. We first tested rhFIX production in the human embryonic kidney 293 cells (293). Next, we tested a hepatic cell line (HepG2) because FIX is primarily expressed in the liver. Our results reveal that intracellular rhFIX expression was more efficient in HepG2/rhFIX (46%) than in 293/rhFIX (21%). The activated partial thromboplastin time test showed that HepG2/rhFIX expressed biologically active rhFIX 1.5 times higher than 293/rhFIX (P = 0.016). Recovery of rhFIX from the HepG2 by reversed‐phase chromatography was straightforward. We found that rhFIX has a pharmacokinetic profile similar to that of FIX purified from human plasma when tested in hemophilic B model. HepG2/rhFIX cell line produced the highest levels of rhFIX, representing an efficient in vitro expression system. This work opens up the possibility of significantly reducing the costs of rhFIX production, with implications for expanding hemophilia B treatment in developing countries.
Running on empty: Does mitochondrial DNA mutation limit replicative lifespan in yeast?
Authors: Dunn Cory D.
Published: August 2011

Mitochondrial DNA (mtDNA) mutations escalate with increasing age in higher organisms. However, it has so far been difficult to experimentally determine whether mtDNA mutation merely correlates with age or directly limits lifespan. A recent study shows that budding yeast can also lose functional mtDNA late in life. Interestingly, independent studies of replicative lifespan (RLS) and of mtDNA‐deficient cells show that the same mutations can increase both RLS and the division rate of yeast lacking the mitochondrial genome. These exciting, parallel findings imply a potential causal relationship between mtDNA mutation and replicative senescence. Furthermore, these results suggest more efficient methods for discovering genes that determine lifespan.
Flow‐injection chemiluminescence determination of melamine in urine and plasma
Authors: Tang Xiaoshuang , Shi Xiyan , Tang Yuhai , Yue Zhongjin , He Qiqi
Published: August 2011

A novel flow‐injection chemiluminescence method for the determination of melamine in urine and plasma was developed. It was found that melamine can remarkably enhance chemiluminescence emission from the luminol–K3Fe(CN)6 system in an alkaline medium. Under the optimum conditions, chemiluminescence intensity had a good linear relationship with the concentration of melamine in the range 9.0 × 10–9–7.0 × 10–6 g/mL, with a correlation coefficient of 0.9992. The detection limit (3σ) was 3.5 ng/mL. The method has been applied to determine the concentration of melamine in samples using liquid–liquid extraction. Average recoveries of melamine were 102.6% in urine samples and 95.1% in plasma samples. The method provided a reproducible and stable approach for the sensitive detection of melamine in urine and plasma samples. Copyright © 2011 John Wiley & Sons, Ltd.
Structure of micelle‐bound adrenomedullin: A first step toward the analysis of its interactions with receptors and small molecules
Authors: Pérez‐Castells Javier , Martín‐Santamaría Sonsoles , Nieto Lidia , Ramos Ana , Martínez Alfredo , Pascual‐Teresa Beatriz de , Jiménez‐Barbero Jesús
Published: August 2011

Adrenomedullin (AM) is a regulatory peptide which plays many physiological roles including vasodilatation, bronchodilatation, hormone secretion regulation, growth, apoptosis, angiogenesis, and antimicrobial activities, among others. These regulatory activities make AM a relevant player in the pathophysiology of important diseases such as cardiovascular and renal conditions, cancer, and diabetes. Therefore, molecules that target the AM system have been proposed as having therapeutic potential. To guide the design and characterization of such molecules, we elucidated the three‐dimensional structure of AM in a membrane mimicking medium using NMR spectroscopy methods. Under the employed experimental conditions, the structure can be described as composed by a central α‐helical region, spanning about one third of its total length, flanked by two disordered segments at both N‐ and C‐termini. The structure of AM in water is completely disordered. The 22–34 region of AM has a general tendency to adopt a helical structure under the employed experimental conditions. Furthermore, the study of the interaction of AM with two of its modulators has also been performed by using chemical shift perturbation analysis NMR methods with two‐dimensional (2D)‐TOCSY experiments, assisted with molecular modeling protocols. We expect these results will help in better understanding the interactions of AM with its receptor and binding proteins/molecules and in the development of novel modulators of AM activities. © 2011 Wiley Periodicals, Inc. Biopolymers 97: 45–53, 2012.
Extrusion based rapid prototyping technique: An advanced platform for tissue engineering scaffold fabrication
Authors: Hoque M. Enamul , Chuan Y. Leng , Pashby Ian
Published: August 2011

Advances in scaffold design and fabrication technology have brought the tissue engineering field stepping into a new era. Conventional techniques used to develop scaffolds inherit limitations, such as lack of control over the pore morphology and architecture as well as reproducibility. Rapid prototyping (RP) technology, a layer‐by‐layer additive approach offers a unique opportunity to build complex 3D architectures overcoming those limitations that could ultimately be tailored to cater for patient‐specific applications. Using RP methods, researchers have been able to customize scaffolds to mimic the biomechanical properties (in terms of structural integrity, strength, and microenvironment) of the organ or tissue to be repaired/replaced quite closely. This article provides intensive description on various extrusion based scaffold fabrication techniques and review their potential utility for TE applications. The extrusion‐based technique extrudes the molten polymer as a thin filament through a nozzle onto a platform layer‐by‐layer and thus building 3D scaffold. The technique allows full control over pore architecture and dimension in the x‐ and y‐ planes. However, the pore height in z‐direction is predetermined by the extruding nozzle diameter rather than the technique itself. This review attempts to assess the current state and future prospects of this technology. © 2011 Wiley Periodicals, Inc. Biopolymers 97: 83–93, 2012.
Application of a novel thermostable NAD(P)H oxidase from hyperthermophilic archaeon for the regeneration of both NAD+ and NADP+
Authors: Wu Xi , Kobori Hiroki , Orita Izumi , Zhang Chong , Imanaka Tadayuki , Xing Xin‐Hui , Fukui Toshiaki
Published: August 2011

A novel thermostable NAD(P)H oxidase from the hyperthermophilic archaeon Thermococcus kodakarensis KOD1 (TkNOX) catalyzes oxidation of NADH and NADPH with oxygen from atmospheric air as an electron acceptor. Although the optimal temperature of TkNOX is >90°C, it also shows activity at 30°C. This enzyme was used for the regeneration of both NADP+ and NAD+ in alcohol dehydrogenase (ADH)‐catalyzed enantioselective oxidation of racemic 1‐phenylethanol. NADP+ regeneration at 30°C was performed by TkNOX coupled with (R)‐specific ADH from Lactobacillus kefir, resulting in successful acquisition of optically pure (S)‐1‐phenylethanol. The use of TkNOX with moderately thermostable (S)‐specific ADH from Rhodococcus erythropolis enabled us to operate the enantioselective bioconversion accompanying NAD+ regeneration at high temperatures. Optically pure (R)‐1‐phenylethanol was successfully obtained by this system after a shorter reaction time at 45–60°C than that at 30°C, demonstrating an advantage of the combination of thermostable enzymes. The ability of TkNOX to oxidize both NADH and NADPH with remarkable thermostability renders this enzyme a versatile tool for regeneration of the oxidized nicotinamide cofactors without the need for extra substrates other than dissolved oxygen from air. Biotechnol. Bioeng. 2012;109: 53–62. © 2011 Wiley Periodicals, Inc.
Construction of a recombinant Trichoderma reesei strain expressing Aspergillus aculeatus β‐glucosidase 1 for efficient biomass conversion
Authors: Nakazawa Hikaru , Kawai Tetsushi , Ida Noriko , Shida Yosuke , Kobayashi Yoshinori , Okada Hirofumi , Tani Shuji , Sumitani Jun‐ichi , Kawaguchi Takashi , Morikawa Yasushi , Ogasawara Wataru
Published: August 2011

To develop a Trichoderma reesei strain appropriate for the saccharification of pretreated cellulosic biomass, a recombinant T. reesei strain, X3AB1, was constructed that expressed an Aspergillus aculeatus β‐glucosidase 1 with high specific activity under the control of the xyn3 promoter. The culture supernatant from T. reesei X3AB1 grown on 1% Avicel as a carbon source had 63‐ and 25‐fold higher β‐glucosidase activity against cellobiose compared to that of the parent strain PC‐3‐7 and that of the T. reesei recombinant strain expressing an endogenous β‐glucosidase I, respectively. Further, the xylanase activity was 30% lower than that of PC‐3‐7 due to the absence of xyn3. X3AB1 grown on 1% Avicel‐0.5% xylan medium produced 2.3‐ and 3.3‐fold more xylanase and β‐xylosidase, respectively, than X3AB1 grown on 1% Avicel. The supernatant from X3AB1 grown on Avicel and xylan saccharified NaOH‐pretreated rice straw efficiently at a low enzyme dose, indicating that the strain has good potential for use in cellulosic biomass conversion processes. Biotechnol. Bioeng. 2012;109: 92–99. © 2011 Wiley Periodicals, Inc.
Simultaneous determination of lidamycin enediyne chromophore (LDC) and its aromatized derivative (LDCA) using puerarin as internal standard in rat plasma by LC‐MS/MS
Authors: Wen Yanqing , Chen Shuzhen , Meng Zhiyun , Gan Hui , Zhu Xiaoxia , Wu Zhuona , Gu Ruolan , Dou GuiFang
Published: August 2011

Lidamycin (LDM), a promising enediyne antitumor antibiotic, was quantified by detecting lidamycin enediyne chromophore (LDC) using liquid chromatography–tandem mass spectrometry (LC‐MS/MS) for the first time. A simple, rapid and reliable method was developed and validated to determine LDC and its aromatized derivative (LDCA) simultaneously in plasma. Puerarin was used as an internal standard (IS), and plasma samples were pretreated with one‐step precipitation by acetonitrile. Separation was achieved on a reverse‐phase C18 column with a mobile phase composed of methanol and water containing 5 mm ammonium acetate at pH 3.5 in gradient elution mode. Detection was performed on a triple quadrupole tandem mass spectrometer using electrospray ionization (ESI) by multiple reaction monitoring (MRM) in the negative ion mode. Good linearity was obtained over the concentration range of 0.2–100 µg/mL for LDM. Precision and accuracy were validated by RSD% values in the range of 2.6–13.0% and RE% values between −4.6 and 3.8%, respectively. In addition, no specificity and matrix effects were observed. The recovery was found to be 99.2–111.0% and stability in various conditions was found to be acceptable. This method was applied in preclinical pharmacokinetic studies for routine monitoring of LDM in rat plasma. Copyright © 2011 John Wiley & Sons, Ltd.
Investigation into omacetaxine solution stability for in vitro study
Authors: Marenah Lamin , Allan Elaine K. , Mountford Joanne C. , Holyoake Tessa L. , Jørgensen Heather G. , Elliott Moira A.
Published: August 2011

Omacetaxine is a natural product extract originating from Chinese medicine and finding therapeutic use as a potent myelosuppressive agent in leukemia. When planning in vitro cell biology experiments to assess omacetaxine activity against primary leukemic stem cells, it became apparent that the literature rarely describes the in vitro stability of the molecule, although accessible chromatographic methods have been published. Clearly whole organisms vs their component cells will differ in the way in which they handle xenobiotics, with the latter more dependent on physiochemical parameters such as pH and temperature in the absence of active metabolism or excretion. This could impact on the cells' experience of drug in culture. We therefore report here on examination of a modified, high‐performance liquid chromatography (HPLC) method with assessment of degradant production from a 72 h solution stability study, clearly demonstrating that omacetaxine is highly stable in representative cell culture conditions (37 °C, neutral pH) and persists for many days in marked contrast to its short‐half life in vivo. Copyright © 2011 John Wiley & Sons, Ltd.
Biodegradation of medium chain hydrocarbons by Acinetobacter venetianus 2AW immobilized to hair‐based adsorbent mats
Authors: Luckarift Heather R. , Sizemore Susan R. , Farrington Karen E. , Fulmer Preston A. , Biffinger Justin C. , Nadeau Lloyd J. , Johnson Glenn R.
Published: August 2011

The natural attenuation of hydrocarbons can be hindered by their rapid dispersion in the environment and limited contact with bacteria capable of oxidizing hydrocarbons. A functionalized composite material is described herein, that combines in situ immobilized alkane‐degrading bacteria with an adsorbent material that collects hydrocarbon substrates, and facilitates biodegradation by the immobilized bacterial population. Acinetobacter venetianus 2AW was isolated for its ability to utilize hydrophobic n‐alkanes (C10–C18) as the sole carbon and energy source. Growth of strain 2AW also resulted in the production of a biosurfactant that aided in the dispersion of complex mixtures of hydrophobic compounds. Effective immobilization of strain 2AW to the surface of Ottimat™ adsorbent hair mats via vapor phase deposition of silica provided a stable and reproducible biocatalyst population that facilitates in situ biodegradation of n‐alkanes. Silica‐immobilized strain 2AW demonstrated ca. 85% removal of 1% (v/v) tetradecane and hexadecane within 24 h, under continuous flow conditions. The methodology for immobilizing whole bacterial cells at the surface of an adsorbent, for in situ degradation of hydrocarbons, has practical application in the bioremediation of oil in water emulsions. Published 2011 American Institute of Chemical Engineers Biotechnol Prog., 2011
Evaluation of Escherichia coli proteins that burden nonaffinity‐based chromatography as a potential strategy for improved purification performance
Authors: Bartlow Patrick , Tiwari Neha , Beitle Robert R. , Ataai Mohammad M.
Published: August 2011

Escherichia coli is a favored host for rapid, scalable expression of recombinant proteins for academic, commercial, or therapeutic use. To maximize its economic advantages, however, it must be coupled with robust downstream processes. Affinity chromatography methods are unrivaled in their selectivity, easily resolving target proteins from crude lysates, but they come with a significant cost. Reported in this study are preliminary efforts to integrate downstream separation with upstream host design by evaluating co‐eluting host proteins that most severely burden two different nonaffinity‐based column processes. Phosphoenolpyruvate carboxykinase and peptidase D were significant contaminants during serial purification of green fluorescent protein (GFP) by hydrophobic interaction and anion exchange chromatography. Ribosomal protein L25 dominated non‐target binding of polyarginine‐tagged GFP on cation exchange resin. Implications for genetic knockout or site‐directed mutagenesis resulting in diminished column retention are discussed for these and other identified contaminants. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2012
Isolation, Amino Acid Sequence and Biological Activities of Novel Long‐Chain Polyamine‐Associated Peptide Toxins from the Sponge Axinyssa aculeata
Authors: Matsunaga Satoko , Jimbo Mitsuru , Gill Martin B. , Lash‐Van Wyhe L. Leanne , Murata Michio , Nonomura Ken'ichi , Swanson Geoffrey T. , Sakai Ryuichi
Published: August 2011

A novel family of functionalized peptide toxins, aculeines (ACUs), was isolated from the marine sponge Axinyssa aculeate. ACUs are polypeptides with N‐terminal residues that are modified by the addition of long‐chain polyamines (LCPA). Aculeines were present in the sponge extract as a complex mixture with differing polyamine chain lengths and peptide structures. ACU‐A and B, which were purified in this study, share a common polypeptide chain but differ in their N‐terminal residue modifications. The amino acid sequence of the polypeptide portion of ACU‐A and B was deduced from 3′ and 5′ RACE, and supported by Edman degradation and mass spectral analysis of peptide fragments. ACU induced convulsions upon intracerebroventricular (i.c.v.) injection in mice, and disrupted neuronal membrane integrity in electrophysiological assays. ACU also lysed erythrocytes with a potency that differed between animal species. Here we describe the isolation, amino acid sequence, and biological activity of this new group of cytotoxic sponge peptides.
Gold‐Catalyzed, Intramolecular, Oxygen‐Transfer Reactions of 2‐Alkynyl‐1,5‐diketones or 2‐Alkynyl‐5‐ketoesters: Scope, Expansion, and Mechanistic Investigations on a New [4+2] Cycloaddition
Authors: Liu Le‐Ping , Malhotra Deepika , Jin Zhuang , Paton Robert S. , Houk K. N. , Hammond Gerald B.
Published: August 2011

The gold‐catalyzed intramolecular oxygen‐transfer reactions of 2‐alkynyl‐1,5‐diketones or 2‐alkynyl‐5‐ketoesters—obtained from tetra‐n‐butylammonium fluoride mediated Michael addition of activated allenes to electron‐deficient olefins—furnished cyclopentenyl ketones under very mild conditions. These reactions proceeded much easier and faster than similar reactions reported in literature, and the corresponding products were obtained in very good yields. Mechanistic investigations on the cycloisomerization were carried out by means of both 18O isotopic experiments and quantum chemical calculations. The results from both, the designed isotopic experiments and theoretical calculations, satisfactorily supported the novel proposed intramolecular [4+2] cycloaddition of a gold‐containing furanium intermediate to a carbonyl group, instead of the previous well‐accepted [2+2] pathway.
Bell‐Like [Ga5] Clusters in Eu3Li5+xGa5–x (x = 0.15)
Authors: Fedorchuk Anatolii , Prots Yurii , Schnelle Walter , Grin Yuri
Published: August 2011

The new ternary gallide Eu3Li5+xGa5–x was synthesized from its constituent elements that were heated at 900 °C and then subsequently annealed at 300 °C for 10 months. The crystal structure was established from single‐crystal diffraction data. A new type of discrete gallium cluster was found inEu3Li5+xGa5–x, namely a bell‐like [Ga5] unit with one single‐,one four‐ and three three‐bonded atoms. On the basis of its structural features, magnetic properties and calculated electronic density of states (DOS), the title compound is represented as [Eu2+]3[Li+]5[(1b)Ga4–]1[(3b)Ga2–]3[(4b)Ga1–]1 (xb = number of bonds, where x = 1–4). The new structural unit observed in this compound is compared with other [Gan] (n = 2–6) clusters found in binary gallium compounds.