bluuebunny/crossref_metadata_2025 huggingface dataset:
Lignin‐based activated carbon fibers and controllable pore size and properties
Authors: Shen Qing , Zhang Tao , Zhang Wen‐Xin , Chen Shuai , Mezgebe Mebrahtu
Published: February 2011

Several lignin‐based activated carbon fibers (ACFs) were prepared by initial synthesis of lignin–phenol–formaldehyde (LPF) resins with varied lignin contents, 8–20%, respectively, and then the melt spinning and thermal treatments. Because the guaiacyl groups of lignin reacted with the formaldehyde, the role of lignin played becomes a dominator for controlling the thermal properties of LPF resin and the pore size and related properties of ACFs. This was proven by the comparison of the scanning electron microscope photographs of all prepared ACFs. FTIR spectra showed that the ACFs were structured by lignin‐contributed carbons. The porosity and adsorption behavior of these ACFs were also studied and compared. Results showed that the ACFs with 14% lignin content have better pore structure and adsorption properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Dynamic rheology and morphology of polylactide/organic montmorillonite nanocomposites
Authors: Wang Biao , Wan Tong , Zeng Wei
Published: February 2011

The effects of organic montmorillonite (OMMT) on the rheological behaviors and phase morphology of polylactide (PLA) were investigated. The rheological behaviors of nanocomposites showed mainly dependence on both temperature and OMMT content. At low OMMT loading (1 wt %), the complex viscosities showed a Newtonian plateau in low frequency region at low temperatures and converted to a shear‐thinning behaviors with increasing temperature. In comparison, at high OMMT loadings (above 5 wt %), strong shear‐thinning behaviors were observed in the full range of frequencies and temperatures. The results demonstrated rheology of PLA/OMMT is highly sensitive to the nanofillers filled materials. A pseudo‐solid‐like behavior at long scale time in the hybrids with OMMT loading was higher than 5 wt %, this response was related to the formation of a network structure across the polymer matrix due to strong interactions of PLA and OMMT that confined the relaxation process of the macromolecules. X‐ray diffraction and transmission electron microscopy indicated the nanocomposites at low OMMT loading were mainly exfoliated and intercalated nanocomposites were gradually formed with increasing OMMT loading. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Kinetics of UV‐initiated RAFT crosslinking polymerization of dimethacrylates
Authors: Zhuo Ding , Ruan Yingbo , Zhao Xuemei , Ran Rong
Published: February 2011

The UV‐initiated RAFT polymerizations of a series of poly(ethylene glycol) dimethacrylates (PEGDMA) were investigated using differential scanning photocalorimetry (DPC) at room temperature. The rate of the RAFT system was much lower than that of a conventional free radical polymerization. A mild autoacceleration occurred as the addition reaction became diffusion controlled. The influence of the spacer length (CH2CH2O)x between the vinyl moieties of the dimethacrylates on the polymerization kinetics was examined. The polymerization rate of PEGDMA decreased with an increased x value from 4 to 9, but it increased with a further increased x value from 9 to 14. Mechanical properties of the resulting polymers were also examined by dynamic mechanical analysis (DMA). It was concluded that the presence of the RAFT agent during polymerization of multifunctional monomers did not have an effect on the heterogeneity of the polymer network. In comparison with three different PEGDMAs, the PEGDMA with the longest spacer formed the most homogeneous networks with a lower crosslinking density. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and characterization of poly(ethylene glycol)‐b‐poly(ε‐caprolactone)‐b‐poly(2‐(2‐aminoethyl amino)ethyl methacrylate) triblock copolymers as efficient gene delivery vectors
Authors: Yuan Zhe‐Fan , Li Feng , Ma Ming , Cheng Si‐Xue , Zhuo Ren‐Xi
Published: February 2011

In this study, ABC‐type triblock copolymers, poly(ethylene glycol)‐b‐poly(ε‐caprolactone)‐b‐poly(2‐(2‐aminoethyl amino) ethyl methacrylate)s (PEG‐PCL‐PAEAEMAs), composed of novel poly(2‐(2‐aminoethyl amino) ethyl methacrylate) (PAEAEMA) that have a primary and a secondary amino group in each monomeric unit, were synthesized successfully. It was found that the length of PAEAEMA segments did not have obvious influence on the DNA‐binding capacity and other biophysical properties (size and zeta potential values of polymer/pDNA complexes) , but longer PAEAEMA chains led to a better buffering capacity. The triblock copolymers could mediate efficient gene expression that was similar to branched 25‐kDa polyethylenimine (25 kDa PEI) in the absence of serum and even superior to 25 kDa PEI in the presence of serum in COS‐7 cells. Low cytotoxicity of these polymers was also found in COS‐7 cells. As a result, PEG‐PCL‐PAEAEMAs are attractive candidates as serum‐tolerable gene carriers in biomedical field. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Core‐shell method of synthesis, characterizations, and ac conductivity studies of polyaniline/n‐TiO2 composites
Authors: Roy Aashis S. , Anilkumar Koppalkar R. , Prasad M. V. N Ambika
Published: February 2011

Polyaniline/nano‐titanium dioxide composites (PANI/n‐TiO2) were prepared using α‐dextrose as surfactant and ammonium per sulfate as oxidant. The PANI/n‐TiO2 composite is characterized by Fourier transform infrared spectra and confirmed the presence of benzenoid and qunoide ring structures and also formation of free ions. The transmission electron microscopy study reveals that the size of TiO2 is in the order of 7 nm where as the composite size is of the order of 13 nm; further, it is observed that the TiO2 particles are intercalated to form a core shell of PANI. The X‐ray diffraction (XRD) studies show that the monoclinic structure of the composites. ac Conductivity, permittivity, and tangent loss studies on these samples suggest that these composites may be well suited for gas sensor. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Microbial modification of polyethylene terephthalate fabric
Authors: Akkaya Alper , Pazarlioglu Nurdan Kasikara
Published: February 2011

A great disadvantage of synthetic fibers is their low hydrophilicity. Polyester fibers are particularly hydrophobic. In the first place, this affects the processability of the fibers. The surfaces are not easily wetted, thus impeding the application of finishing compounds and coloring agents. In addition, a hydrophobic material hinders water from penetrating into the pores of fabric. An additional advantage is a decrease in build‐up of electrostatic charge. Besides an improved processability of hydrophilic textiles, a number of advantages from the consumer's point of view are improved washability, as the water can remove hydrophobic stains more easily, and enhanced wearing comfort due to greater water absorbency. For these reasons, hydrophilicity of polyester fabrics was improved using Trametes versicolor. Incubation conditions were determined as; the polyester fabrics were incubated for 10 days at 28°C and 175 rpm. The modification medium was contained 1 g/L glucose and pH of medium was 4. The modification degree was determined according to the contact angle measurements. Water retention values were compatible with contact angle values. FTIR and SEM images showed that the modification occurred on the PET fabric surface. More hydrophilic PET fabric was made by T. versicolor. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Effect of a coupling agent on the properties of hemp‐hurd‐powder‐filled styrene–butadiene rubber
Authors: Wang Jie , Wu Weidong , Wang Wencai , Zhang Jianchun
Published: February 2011

Styrene–butadiene rubber (SBR) composites filled with hemp hurd powder (HP) were prepared with bis(3‐triethoxysilylpropyl) tetrasulfide (Si69) as a coupling agent. The effects of the filler content and coupling agent on the curing characteristics and dynamic mechanical properties of the composites were studied. The results indicate that with increasing filler loading, the torque values increased and the curing time decreased. The mechanical properties improved with increasing filled HP content up to 60 phr. Usually, long fibers led to a sharp decrease in the toughness of the composites, whereas short fibers, such as HP, had a positive effect on the elongation at break within the loading range studied. The extent of the filler–matrix interaction and the scanning electron micrographs of the fractured surfaces confirmed that the addition of Si69 improved the interfacial interaction between HP and the SBR matrix, which led to an increase in the maximum torque and the mechanical properties. Moreover, the coupling agent was helpful in dispersing the filler in the rubber matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and properties of a high‐molecular‐weight poly(amic acid) and polyimide based on 2,2‐bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane
Authors: Zheng Yanhong , Zhai Yu , Li Guangzhu , Guo Baohua , Zeng Xinmiao , Wang Liancai , Yu Hongyan , Guo Jianmei
Published: February 2011

The feasibility of using the conventional two‐step procedure involving the thermal imidization of a high‐molecular‐weight poly(amic acid) (PAA) for the preparation of self‐supporting polyimide (PI) films was studied. Synthesized PAA and PI were analyzed with respect to their molecular weights, chemical structures, and mechanical and thermal properties. The results showed that a high‐molecular‐weight PAA was successfully synthesized from 2,2‐bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane with 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride. The high intrinsic viscosity of PAA was 1.5 dL/g. Self‐supporting PI films were successfully prepared by the thermal imidization of PAA and reached maximum tensile strength, tensile modulus, and elongation at break values of 103 MPa, 2.2 GPa, and 10.7%, respectively. The PI films were stable to 426–483°C (the 5% weight loss temperature) and had a glass transition at 271–283°C. All these results indicate that the conventional two‐step procedure involving thermal imidization is a promising method for preparing self‐supporting PI films with reasonable levels of mechanical and thermal properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
A gradient anodic oxidation method for treating polyacrylonitrile‐based high‐modulus carbon fibers
Authors: Hou Yongping , Sun Tongqing , Wang Haojing
Published: February 2011

We describe a gradient anodic oxidation method. Polyacrylonitrile‐based high‐modulus carbon fibers were treated by the conventional and gradient anodic oxidation methods. The results show that the carbon fibers treated by the gradient method possessed a more stable tensile strength, larger NaOH uptake, shallower striations, flatter fracture surface of composites, and better interlaminar shear strength compared to those treated by the conventional method. This indicated that the gradient method was more effective in restricting the etching reaction and improving the adhesion between the carbon fibers and matrix, and we give a suggested explanation of the mechanisms. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Diphenylselenonium 2,3,4,5‐tetraphenylcyclopentadienylide‐initiated polymerization of styrene and acrylonitrile: Synthesis, characterization, reactivity ratios, and thermal properties
Authors: Singh Anamika , Kamal Meet , Singh D. K.
Published: February 2011

Solution copolymerization of styrene (Sty) and acrylonitrile (AN) was carried out in dioxane at 60 ± 1°C for 90 min using diphenylselenonium 2,3,4,5‐tetraphenylcyclopentadienylide (selenonium ylide) as radical initiator. The kinetic expression is as follows: Rp ∼ [Ylide]0.5 [Sty]1.0 [AN]1.0. The overall activation energy is 28.72 kJ mol−1. The composition of copolymer calculated from 1H‐NMR and elemental analysis was used to evaluate reactivity ratio as r1 (Sty) = 0.351 and r2 (AN) = 0.0185, using kelen‐Tudos method. It confirmed the alternating nature of the copolymer. The copolymer was characterized using Fourier transform infrared (FTIR) spectroscopy, 1H‐NMR, 13C‐NMR, differential scanning calorimetry, and thermal gravimetric analysis. Electron spin resonance spectroscopy confirmed the presence of the phenyl radical responsible for initiation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
A thorough study on the relationships between dispersion quality and viscoelastic properties in carbon black filled SBR compounds
Authors: Leblanc Jean L. , Putman Matthew , Pianhanuruk Ekkawit
Published: February 2011

A series of carbon black filled SBR 1500 compounds (without curatives) were prepared in carefully controlled lab‐mixing conditions so that filler content ranged from 0 to 50 phr, with the usual compounding ingredients. Carbon Black agglomeration and dispersion quality were assessed through an advanced microscopic technique with automated data treatment. Linear and nonlinear viscoelastic properties were evaluated using a closed cavity torsional rheometer, equipped for Fourier Transform rheometry experiments. In the linear viscoelastic regime, dynamic moduli mastercurves were derived from experiments in the 60−160°C temperature range. In the nonlinear viscoelastic regime, complex modulus and torque harmonics variation with strain amplitude were investigated at 100°C and frequency 0.5 and 1.0 Hz. Relationships between dispersion quality, carbon black loading and mixing parameters were investigated so that dispersion appears better when the filler loading is above a critical level that to some extent (but not exactly) corresponds to the theoretical percolation threshold (around 13%). Linear and nonlinear viscoelastic measurements demonstrate and quantify the role played by plasticizing compounding ingredients, that is, processing oil, stearic acid and other chemicals, with nearly no significant effect of mixing energy. At least 10−15 phr carbon black are necessary to recover the modulus loss associated with this plasticizing effect. Nonlinear results and particularly the torque harmonics reveal a number of details as to how the compounding ingredients do affect the viscoelastic behavior, with expectedly the carbon black playing the major role. By fitting results with mathematically simple models, all of the observed effects can be summarized in a rather limited number of parameters so that the effects of compounding ingredients can be studied in details. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Effects of POSS particles on the mechanical, thermal, and morphological properties of PLA and Plasticised PLA
Authors: Turan Dilek , Sirin Humeyra , Ozkoc Guralp
Published: February 2011

The mechanical, thermal, and morphological properties of melt compounded aminopropylisobutyl‐polyhedral oligomeric silsesquioxane (POSS)/poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG)‐plasticized PLA composites were investigated. It was found that the addition of POSS to the PLA reduced the melt viscosity of the composites acting as a lubricating agent. Dynamic mechanical analysis and tensile tests showed that the modulus and elongation at break values improved at low (1% and 3%) POSS loading levels. Scanning electron microscopy observation indicated that POSS particles were well dispersed in both PLA and plasticized PLA. The interfacial interaction of POSS with the polymer matrix was found to be better in the presence of plasticizer. The presence of POSS also affected the thermal properties of the PLA and plasticized PLA. It was revealed from DSC that POSS particles acted as a nucleating agent for PLA. Moreover, the percent crystallinity was found to be higher in the presence of POSS for both PLA and plasticized PLA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Miscibility and crystallization behaviors of biodegradable poly(butylene succinate‐co‐butylene terephthalate)/phenoxy blends
Authors: Li Zhisheng , Yang Fang , Qiu Zhaobin
Published: February 2011

Miscibility and crystallization behaviors of biodegradable poly(butylene succinate‐co‐butylene terephthalate) (PBST)/poly(hydroxyl ether biphenyl A) (phenoxy) blends were investigated with various techniques in this work. PBST and phenoxy are completely miscible as evidenced by the single composition‐dependent glass transition temperature over the entire blend compositions. Nonisothermal melt crystallization peak temperature is higher in neat PBST than in the blends at a given cooling rate. Isothermal melt crystallization kinetics of neat and blended PBST was studied and analyzed by the Avrami equation. The overall crystallization rate of PBST decreases with increasing crystallization temperature and the phenoxy content in the PBST/phenoxy blends; however, the crystallization mechanism of PBST does not change. Moreover, blending with phenoxy does not modify the crystal structure but reduces the crystallinity degree of PBST in the PBST/phenoxy blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
High transmittance and environment‐friendly flame‐resistant optical resins based on poly(methyl methacrylate) and cyclotriphosphazene derivatives
Authors: Guo Ya‐Ni , Qiu Jin‐Jun , Tang He‐Qing , Liu Cheng‐Mei
Published: February 2011

Highly transparent optical resins based on poly(methyl methacrylate) (PMMA) and two cyclotriphosphazene derivatives which acting as halogen‐free flame retardants were prepared. The refractive indices, visible light transmittance, water absorption, flame‐resistant characteristic, and the mechanical properties of the resins were studied. Comparing with pure PMMA, the as‐prepared resins with the two additives exhibited higher refractive index (nd), longer UV cutoff wavelength and better surface hardness. The water absorption of the resins was decrease with increasing of the additives. The visible light transmittance of all the samples adding Additive A was higher than 90%. When the weight ratio of additive/MMA was 20/100, the limiting oxygen index (LOI) of the samples were 26 (with Additive A) and 22 (with Additive B), respectively. The surface hardness was increased from HB to 2H with increasing the content of the additives, and the impact and the tensile strength changed little for the formulas of the additives lower than 30% by weight. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Effect of porogenic solvent on the morphology, recognition and release properties of carbamazepine‐molecularly imprinted polymer nanospheres
Authors: Esfandyari‐Manesh Mehdi , Javanbakht Mehran , Atyabi Fatemeh , Badiei Alireza , Dinarvand Rassoul
Published: February 2011

This study focus on the effect of the porogenic solvent on the morphology, recognition, and drug release of carbamazepine‐molecularly imprinted polymer nanospheres prepared by precipitation polymerization. The scanning electron microscopy (SEM) images and Brunauer‐Emmett‐Teller (BET) analysis showed that molecularly imprinted polymer (MIP) prepared by acetonitrile exhibited a regular spherical shape at the nanoscale with a high degree of monodispersity, specific surface area of 242 m2 g−1, and pore volume of 1 mL g−1, while those using chloroform and toluene produced irregular polymer particles with low specific surface area and pore volume. MIP prepared by acetonitrile/chloroform (1 : 1, v/v) showed mediator texture properties compared to MIPs obtained by acetonitrile or chloroform. Results from saturation and displacement assays indicated that the imprinted nanospheres with binding capacity of 2.85 (mg CBZ/g polymer) had high specific affinity to CBZ in contrast to nonimprinted nanospheres (1.63 mg CBZ/g polymer). The imprinted nanospheres with 2.4 selectivity factor had good recognition to CBZ than analog template of oxcarbazepine. Moreover, release studies showed that 20% of loaded CBZ was released from the imprinted nanospheres within the initial 6 h, while another 80% of CBZ was released in the following 9 days. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Morphology and electrical properties of polymethylmethacrylate/poly(styrene‐co‐acrylonitrile)/multi‐walled carbon nanotube nanocomposites
Authors: Lee Minho , Jeon Hyeonyeol , Min Byong Hun , Kim Jeong Ho
Published: February 2011

Nanocomposites of blends of polymethylmethacrylate (PMMA) and poly(styrene‐co‐acrylonitrile) (SAN) with multi‐walled carbon nanotubes (MWCNTs) were prepared by melt mixing in a twin‐screw extruder. The dispersion state of MWCNTs in the matrix polymers was investigated using transmission electron microscopy. Interestingly enough, in most of the nanocomposites, the MWCNTs were observed to be mainly located at SAN domains, regardless of the SAN compositions in the PMMA/SAN blend and of the processing method. One possible reason for this morphology may be the π–π interactions between MWCNTs and the phenyl ring of SAN. The shift in G‐band peak observed in the Raman spectroscopy may be the indirect evidence proving these interactions. The percolation threshold for electrical conductivity of PMMA/SAN/MWCNT nanocomposites was observed to be around 1.5 wt %. Nanocomposites with PMMA‐rich composition showed higher electrical conductivity than SAN‐rich nanocomposites at a fixed MWCNT loading. The dielectric constant measurement also showed composition‐dependent behavior. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Osteoarthritis induction leads to early and temporal subchondral plate porosity in the tibial plateau of mice: An in vivo microfocal computed tomography study
Authors: Botter Sander M. , van Osch Gerjo J. V. M. , Clockaerts Stefan , Waarsing Jan H. , Weinans Harrie , van Leeuwen Johannes P. T. M.
Published: February 2011

Objective

In osteoarthritis (OA), changes occur in both cartilage and subchondral bone. The subchondral bone plate facilitates normal cross‐talk between articular cartilage and trabecular subchondral bone, and adaptive changes in the plate due to OA may therefore disturb cross‐talk homeostasis. To investigate these changes over time, we examined the cartilage–subchondral bone interface using a combined approach of histologic analysis and in vivo microfocal computed tomography.

Methods

Sixteen‐week‐old male C57BL/6 mice (n = 32) received intraarticular injections of collagenase in 1 joint to induce instability‐related OA and received saline injections in the contralateral knee joint (control joint). At 2, 4, 6, 10, and 14 weeks after injection, changes in the tibial subchondral bone plate and subchondral trabeculae were analyzed.

Results

Two weeks after injection, collagenase‐injected joints had significantly more cartilage damage and osteophytosis than did control joints. Osteoclast activity directly underneath the subchondral bone plate was significantly elevated in collagenase‐injected joints compared to control joints (mean ± SEM osteoclast surface/bone surface 11.07 ± 0.79% versus 7.60 ± 0.81%), causing the plate to become thinner and creating a large increase in subchondral bone plate porosity (mean ± SEM cumulative porosity volume 0.05 ± 0.04 × 10−3 mm3 in control joints versus 2.52 ± 0.69 × 10−3 mm3 in collagenase‐injected joints). Four weeks after injection, the previously formed perforations disappeared, coinciding with a significant rise in osteoblast activity in the subchondral trabecular bone in collagenase‐injected joints compared to control joints (mean ± SEM bone formation rate/bone surface 0.62 ± 0.13 μm3/μm2 per day versus 0.30 ± 0.03 μm3/μm2 per day).

Conclusion

The current study is the first to provide quantitative longitudinal data on the dynamic changes in the subchondral bone plate after OA induction. The development of plate perforations may enhance mutual interaction between subchondral trabeculae, bone marrow cells, and the articular cartilage in OA.
The TEDS framework for assessing information systems from a human actors' perspective: Extending and repurposing Taylor's Value‐Added Model
Authors: Scholl Hans J. , Eisenberg Michael B. , Dirks Lee , Carlson Timothy S.
Published: February 2011

Developed in the early 1980s—well before Internet and web‐based technologies had arrived—Taylor's Value‐Added Model introduced what is now better known as the human‐actors' needs perspective on information systems/information technology (IS/IT) artifacts. Taylor distinguished six top‐level criteria that mattered most to human actors when using IS/IT artifacts. We develop this approach further and present the TEDS framework as an analytical instrument for actor‐ and utilization‐specific evaluation of IS/IT artifacts as well as a practical tool for moderating and formulating design specifications. We use the empirical case of a comprehensive comparative professional sports team web site evaluation project to illustrate the power and versatility of the extended analytical framework.
Design of Interpenetrated Networks of Mesostructured Hybrid Silica and Nonconductive Poly(vinylidene fluoride)–Cohexafluoropropylene (PVdF–HFP) Polymer for Proton Exchange Membrane Fuel Cell Applications
Authors: Pereira Franck , Chan Alida , Vallé Karine , Palmas Pascal , Bigarré Janick , Belleville Philippe , Sanchez Clément
Published: February 2011

Organic–inorganic hybrid membranes of poly(vinylidene fluoride)–cohexafluoropropylene (PVdF–HFP) and mesostructured silica containing sulfonic acid groups were synthesized by using the sol‐gel process. These hybrid membranes were prepared by in situ co‐condensation of tetraethoxysilane and an organically modified silane (ormosil) by a self‐assembly route using organic surfactants as templates for tuning the architecture of the hybrid organosilica component. In this paper, we describe the elaboration and characterization of hybrid membranes all the way from the precursor solution to the evaluation of the fuel cell performances. These hybrid materials were extensively characterized by using NMR and IR spectroscopy, electron microscopy, or impedance spectroscopy so as to determinate their physicochemical and electrochemical properties. Even though the ion‐exchange capacity (IEC) was quite weak, the first fuel cell tests performed with these hybrid membranes show promising results relative to optimized Nafion 112 thanks to great water management of the silica inside the hydrophobic polymer.
Nonlinear model predictive control with regulable computational cost
Authors: He Y. Q. , Han J. D.
Published: February 2011

Nonlinear model predictive control (NMPC) suffers from problems of closed loop instability and huge computational burden, which greatly limit its applications in real plants. In this paper, a new NMPC algorithm, whose stability is robust with respect to regulable computational cost, is presented. First, a new generalized pointwise min‐norm (GPMN) control, as well as its analytic form considering a super‐ball type input constraint, is given. Second, the GPMN controller is integrated into a normal NMPC algorithm as a structure of control input profile to be optimized, called GPMN enhanced NMPC (GPMN‐ENMPC). Finally, a numerical example is presented and simulation results exhibit the advantage of the GPMN‐ENMPC algorithm: computational cost can be regulated according to the computational resources with guaranteed stability.

Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Exponential stabilization of uncertain time‐delay linear systems with Markovian jumping parameters
Authors: Huang He , Feng Gang
Published: February 2011

This paper studies the exponential stabilization problem of uncertain time‐delay linear systems with Markovian jumping parameters. A novel delay decomposition approach is developed to derive delay‐dependent conditions under which the closed‐loop control system is mean square exponentially stable for all admissible uncertainties. It is shown that the feedback gain matrices and the decay rate can be obtained by solving coupled linear matrix inequalities. Moreover, the difficulties arising from searching for tuning parameters in the existing methods are overcome.

Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Bewehrte Elastomerlager
Authors: Block Tobias
Published: February 2011

Der Aufsatz erläutert das Tragverhalten bewehrter Elastomerlager unter kombinierten Druck‐ und Verdrehbeanspruchungen. Anhand von experimentellen Untersuchungen an 34 Probekörpern aus Chloropren‐ und Naturkautschuk mit Grundflächen zwischen 150 mm × 300 mm und 600 mm × 700 mm werden die maßgebenden Einflüsse auf die Höhe der rückstellenden Momente dargestellt. Dabei sind sowohl geometrische als auch äußere Einflüsse wie Temperatur und Belastungszustände Bestandteil der Analysen. Es wird gezeigt, dass die experimentellen Ergebnisse systematisch auf der unsicheren Seite liegende hohe Differenzen im Vergleich zu den normativen Berechnungen aufweisen. Auf Basis der Untersuchungen können die gewonnenen Erkenntnisse für die Entwicklung neuer Berechnungsmodelle für Rückstellmomente bewehrter Elastomerlager genutzt werden, die die Einflüsse aus zentrischer Druckbeanspruchung und Temperatur berücksichtigen.

Laminated Elastomeric Bearings — Experimental investigation and new computational models. The report describes the load bearing behaviour of laminated elastomeric bearings under combined compression and uniaxial rotation. The main focus is the experimental description of the factors which influence the restoring moments. Beside the dimensions, the layer construction and the rubber mixture also external parameters like pressure, rotation angle and temperature have been taken into account. Over 500 single tests on 34 specimens with dimensions between 150 mm x 300 mm and 600 mm x 700 mm have been conducted which show major variation compared to the design values according to EN 1337‐3. On the basis of the experimental results new models for determining restoring moments of elastomeric bearings are developed. These models are able to consider the influence of the applied pressure as well as the nonlinearity of the rotation angle and the temperature.
Sicherstellung der Dauerhaftigkeit von Großbrücken aus Beton unter besonders korrosiven Einwirkungen
Authors: Raupach Michael
Published: February 2011

Brücken aus Stahl‐ und Spannbeton werden heute i. d. R. für Nutzungsdauern von 100 Jahren geplant. Insbesondere bei Großbrücken liegen häufig Bedingungen vor, die besondere Lösungen erfordern, wie z. B. bei außerordentlichen korrosiven Beanspruchungen. Beispielhaft wird in diesem Aufsatz die Situation von Pfeilern im Meerwasser näher beleuchtet, die einem ständigen Chloridangriff unterliegen. Soll die Dauerhaftigkeit beispielsweise durch besonders hohe Qualität der Betondeckung erreicht werden, so sind besondere Nachweise zu führen, für die in den letzten Jahren interessante probabilistische Bemessungsansätze entwickelt wurden (s. z. B. [1] bis [3]). Ferner kann die Dauerhaftigkeitsprognose durch Einsatz von Monitoringsystemen kontinuierlich zugeschärft werden, so dass durch Anwendung der Sicherheitsbetrachtungen wirtschaftliche Lösungen ermöglicht werden. In dieser Veröffentlichung wird anhand der Pfeiler der mit 36 km längsten Meeresbrücke der Welt gezeigt, wie die Dauerhaftigkeit unter schwierigen Bedingungen über einen geplanten Nutzungszeitraum von 100 Jahren sichergestellt wird.

Design for Durability of Large Concrete Bridges Under Severe Corrosive Attack. Nowadays bridges made of reinforced or prestressed concrete are usually designed for a service life‐time of 100a. Especially for large bridges often conditions are present, which require special solutions, as e. g. extra ordinarily corrosive exposure condi tions. In this paper exemplarily the situation of piles in seawater are discussed more in detail, which are subject to permanent chloride attack. If durability shall be achieved e. g. especially high quality of the concrete cover, special proofs have to be verified, which have been developed during recent years e. g. as probabilistic approaches (see e.g. [1]—[3]). Additionally the prognosis for durability can be updated continuously by using corrosion monitoring systems, allowing economic solutions by using special safety considerations.
Eine neue 10‐MN‐Prüfmaschine für großformatige Bauteile
Authors: Schladitz Frank , Hampel Torsten , Scheerer Silke , Ortlepp Sebastian
Published: February 2011

Im Otto‐Mohr‐Laboratorium der TU Dresden wurde eine 10‐MN‐Säulenprüfmaschine errichtet. Sie dient zur Prüfung von Bauteilen, die eine Spannweite von maximal 15 m, eine Länge von 20 m, eine Breite von 2,5 m und eine Höhe von 3,75 m, bei einem maximalen Bauteilgewicht von 120 t, aufweisen können.

Die Herausforderung beim Bau lag zum einen darin, dass die Prüfmaschine in einer geschlossenen Halle bei laufendem Betrieb errichtet werden musste, und zum anderen auf der Konstruktionsseite, da wegen des schlechten Baugrundes ein in sich geschlossener Kraftfluss erzielt werden musste. Dies wurde durch einen massiven Stahlrahmen und einen Fundamentbalken erreicht, der als beidseitiger Kragarm ausgeführt wurde. Der Fundamentbalken ist in hohem Grade vorgespannt und hochgradig bewehrt, was für die Herstellung einen selbstverdichtenden Beton erforderte. Aus Platzgründen erfolgte die Betonage und die Vorspannung des 275 t schweren Fundamentbalkens oberhalb der Fundamentgrube. Anschließend wurde der Balken über ein ausgeklügeltes Absenksystem in die 4 m tiefe Fundamentgrube abgesenkt und auf den Maschinenrahmen aufgesetzt.

In the Otto‐Mohr‐Laboratory of the TU Dresden a 10‐MN‐ testing machine was mounted. It serves for testing components with a maximum span width of 15 m, length of 20 m, width of 2.50 m and height of 3.75 m, not exceeding a weight of 120 tons.

The challenge was at the one hand having to build it in a closed hall with running operation and on the other hand the construction itself. Due to bad the building lot a self‐contained power transmission was needed. This was achieved by a massive steel frame and a ground beam being completed as a two‐sided cantilever. The ground beam is highly pre‐stressed and strongly reinforced which called for a self‐compacting concrete. Due to the limited space the concreting and pre‐stressing of the 275 tons ground beam was done above the foundation pit. After that the beam was lowered into the 4 m deep foundation pit and put onto the machine frame by an elaborated lowering system.
Involvement of midkine expression in the inhibitory effects of low‐frequency magnetic fields on cancer cells
Authors: Wang Tingting , Nie Yunzhong , Zhao Shuli , Han Yuwang , Du Youwei , Hou Yayi
Published: February 2011

Effects of magnetic fields (MFs) on cancer cells may depend on cell type and exposure conditions. Gene expression levels are different among cancer cells. However, the effect of MFs on cancer cells with different gene expressions is still unclear. In this study, the cancer cell lines BGC‐823, MKN‐45, MKN‐28, A549, SPC‐A1, and LOVO were exposed to a low‐frequency MF. Specific parameters of MFs were determined. Furthermore, the potential of the MF to influence cancer cell growth with midkine (MK) expression was evaluated. Cell proliferation and cell cycle were detected using the CCK‐8 assay and flow cytometry. Cell ultrastructure was observed by transmission electron microscopy. BGC‐823 cells with over‐expression of MK (BGC‐MK cells) and stanniocalcin‐1 were generated by plasmid construction and transfection. Results showed that exposure to a 0.4‐T, 7.5 Hz MF inhibited the proliferation of BGC‐823, MKN‐28, A549, and LOVO cells, but not MKN‐45 and SPC‐A1 cells. Moreover, the inhibitory effect of the MF on BGC‐MK cells was lower (12.3%) than that of BGC‐823 cells (20.3%). Analysis of the cell cycle showed that exposure to the MF led to a significant increase in the S phase in BGC‐823 cells, but not in BGC‐MK cells. In addition, organelle morphology was modified in BGC‐823 cells exposed to the MF. These results suggest that exposure to a 0.4‐T, 7.5 Hz MF could inhibit tumor cell proliferation and disturb the cell cycle. The alteration of MK expression in cancer cells may be related to the inhibitory effect of the MF on these cells. Bioelectromagnetics 32:443–452, 2011. © 2011 Wiley‐Liss, Inc.
Effect of glutathione depletion, hyperthermia, and a 100‐mT static magnetic field on an hsp70/luc reporter system
Authors: Belton Michelle , Prato Frank S. , Carson Jeffrey J.L.
Published: February 2011

Heat shock proteins, in particular hsp70, are induced under conditions of cellular stress. It has been reported that environmental stimuli such as hyperthermia, oxidative stress, and exposure to magnetic fields increase levels of hsp70. It has also been reported that hyperthermia in combination with magnetic field exposure results in a synergistic increase in hsp70 production. We tested the hypothesis that oxidative stress induced by glutathione (GSH) depletion in combination with static magnetic field (SMF) exposure will produce a similar synergistic increase in hsp70 production. We exposed cells to heat, SMF, and diethylmaleate (DEM), which depletes GSH levels alone and in combination with each other, and measured hsp70 production using an hsp70/luciferase reporter and mRNA levels using PCR. We found that treatment with DEM significantly reduced the rate of luciferase bioluminescence production, particularly in the presence of heat. There was no significant effect of a 100‐mT SMF exposure either alone or in combination with heat, DEM, or both on bioluminescence, however there was a significant interaction between SMF and DEM on hsp70 mRNA levels. Therefore, under our exposure conditions, GSH depletion reduced hsp70 levels but a synergistic effect of combining this stress with other external stimuli was only observed at the level of mRNA. Bioelectromagnetics 32:453–462, 2011. © 2011 Wiley‐Liss, Inc.
Structural dynamics of neuropeptide hPYY
Authors: Hegefeld Wendy A. , Kuczera Krzysztof , Jas Gouri S.
Published: February 2011

We have employed a combination of experiment and simulation to characterize the ensemble of structures sampled by human Peptide YY (hPYY), an important member of the neuropeptide Y family. Experimental structural characterization carried out with far UV circular dichroism spectroscopy and Fourier Transform‐Infrared measurements confirmed that the major feature of the secondary structure of hPYY is the α‐helix, encompassing about half the peptide residues, with smaller contributions from turn and β‐sheet like structures. The peptide undergoes thermal denaturation characterized by a melting temperature of 48°C with an enthalpy change of −24.5 kcal/mol and entropy change of −76.2 cal/(mol K). In our computational studies, based on a 4‐μsec MD trajectory generated with the AMBER03 potential, we found excellent agreement of the predicted features with experimental data, including a stable C‐terminal helix, a central turn and conservation of about 80% of measured long‐range NOE contacts. The main structural fluctuations involved partial helix unwinding and large‐scale motions of the N‐terminal. Our joint experimental/computational approach leads to several insights into the biological function of PYY. We conclude that the C‐terminal helix is crucial for the structural integrity of PYY. The structures and motions found in the simulations suggest microscopic explanations for observed changes in biological activity of the peptide upon mutation and truncation. We also performed microsecond‐length MD and replica‐exchange simulations of hPYY with the OPLS‐AA force field, for which computed structures did not agree well with experimental data, predicting significant loss of helicity and NOE contacts. © 2011 Wiley Periodicals, Inc. Biopolymers 95: 487–502, 2011.
Systematic review and meta-analysis of survival following extracorporeal liver support
Authors: Stutchfield B M , Simpson K , Wigmore S J
Published: February 2011

Background

Extracorporeal liver support (ELS) systems offer the potential to prolong survival in acute and acute-on-chronic liver failure. However, the literature has been unclear on their specific role and influence on mortality. This meta-analysis aimed to test the hypothesis that ELS improves survival in acute and acute-on-chronic liver failure.

Methods

Clinical trials citing MeSH terms ‘liver failure’ and ‘liver, artificial’ were identified by searching MEDLINE, Embase and the Cochrane registry of randomized controlled trials (RCTs) between January 1995 and January 2010. Only RCTs comparing ELS with standard medical therapy in acute or acute-on-chronic liver failure were included. A predefined data collection pro forma was used and study quality assessed according to Consolidated Standards of Reporting Trials (CONSORT) criteria. Risk ratio was used as the effect size measure according to a random-effects model.

Results

The search strategy revealed 74 clinical studies including 17 RCTs, five case–control studies and 52 cohort studies. Eight RCTs were suitable for inclusion, three addressing acute liver failure (198 participants) and five acute-on-chronic liver failure (157 participants). The mean CONSORT score was 14 (range 11–20). Overall ELS therapy significantly improved survival in acute liver failure (risk ratio 0·70; P = 0·05). The number needed to treat to prevent one death in acute liver failure was eight. No significant survival benefit was demonstrated in acute-on-chronic liver failure (risk ratio 0·87; P = 0·37).

Conclusion

ELS systems appear to improve survival in acute liver failure. There is, however, no evidence that they improve survival in acute-on-chronic liver failure.
Single-incision laparoscopic right hemicolectomy (Br J Surg 2010; 97: 1881–1883)
Authors: Hewes J , Adamo M
Published: February 2011

The Editors welcome topical correspondence from readers relating to articles published in the Journal. Responses should be sent electronically via the BJS website (http://www.bjs.co.uk). All letters will be reviewed and, if approved, appear on the website. A selection of these will be edited and published in the Journal. Letters must be no more than 250 words in length.
CO2 from alcoholic fermentation for continuous cultivation of Arthrospira (Spirulina) platensis in tubular photobioreactor using urea as nitrogen source
Authors: Matsudo Marcelo C. , Bezerra Raquel P. , Converti Attilio , Sato Sunao , Carvalho João Carlos M.
Published: February 2011

Carbon dioxide released from alcoholic fermentation accounts for 33% of the whole CO2 involved in the use of ethanol as fuel derived from glucose. As Arthrospira platensis can uptake this greenhouse gas, this study evaluates the use of the CO2 released from alcoholic fermentation for the production of Arthrospira platensis. For this purpose, this cyanobacterium was cultivated in continuous process using urea as nitrogen source, either using CO2 from alcoholic fermentation, without any treatment, or using pure CO2 from cylinder. The experiments were carried out at 120 μmol photons m−2 s−1 in tubular photobioreactor at different dilution rates (0.2 ≤ D ≤ 0.8 d−1). Using CO2 from alcoholic fermentation, maximum steady‐state cell concentration (2661 ± 71 mg L−1) was achieved at D = 0.2 d−1, whereas higher dilution rate (0.6 d−1) was needed to maximize cell productivity (839 mg L−1 d−1). This value was 10% lower than the one obtained with pure CO2, and there was no significant difference in the biomass protein content. With D = 0.8 d−1, it was possible to obtain 56% ± 1.5% and 50% ± 1.2% of protein in the dry biomass, using pure CO2 and CO2 from alcoholic fermentation, respectively. These results demonstrate that the use of such cost free CO2 from alcoholic fermentation as carbon source, associated with low cost nitrogen source, may be a promising way to reduce costs of continuous cultivation of photosynthetic microorganisms, contributing at the same time to mitigate the greenhouse effect. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
A laboratory experiment for teaching automation inspired by the smart home
Authors: Alayón S. , González C. , Toledo P.
Published: February 2011

This paper presents a laboratory experiment for teaching Automation. The objective of this project is to allow the students of the Technical Engineering Schools of the University of La Laguna (Spain) to learn the theoretical and practical fundamentals of Automation Systems through a laboratory experiment based on a home automation application. Automation plays an increasingly important role in the centred of Engineering; as a result, several subjects in the curriculum plan at the Engineering School focus on this discipline. In recent years, our teaching efforts have been centred on designing appealing and modern laboratory experiments. With these practical experiments, students acquire a basic knowledge of Automation, along with complementary knowledge of the latest developments in the field. The laboratory session presented in this article draws its inspiration from the Smart Home, a recent field in applied Automation. Due to the impossibility of carrying out the control of a smart installation in a real house, a simulation experiment was designed for educational tasks. A scale model of a house was built, and all the sensors, the actuators and the control system were adapted to this scale model. A Programmable Logic Controller was selected as the control system. © 2011 Wiley Periodicals, Inc. Comput Appl Eng Educ 21:E121–E131, 2013
Remote control of laboratory equipment for basic electronics courses: A LabVIEW‐based implementation
Authors: Popović Božidar , Popović Nataša , Mijić Danijel , Stankovski Stevan , Ostojić Gordana
Published: February 2011

This article describes a LabVIEW‐based implementation of remote control of laboratory equipment for basic Electronics courses. Remote control of laboratory equipment is demonstrated on an example of recording the amplitude characteristics of a T‐notch filter. Overview of traditional, virtual, and remote laboratory features is given, too. Real laboratory setup is presented, including hardware and software components and virtual instruments, as well as solutions for remote laboratory access. Finally, the way of putting the laboratory online and the course of the experiment are shown. © 2011 Wiley Periodicals, Inc. Comput Appl Eng Educ 21:E110–E120, 2013
Educational software tools for the kinematic analysis of mechanisms
Authors: Petuya Víctor , Macho Erik , Altuzarra Oscar , Pinto Charles , Hernandez Alfonso
Published: February 2011

Educational software for the kinematic analysis of planar and spatial mechanisms is presented in this article. This general‐purpose kinematic software has been developed as a complement to Machine Theory lectures. The different modules integrated in the software compute and analyse various kinematic entities, which enable an advanced student to investigate the characteristics of a mechanism. © 2011 Wiley Periodicals, Inc. Comput Appl Eng Educ 22: 72–86, 2014
Mass Transfer Behavior of Annular Ducts under Conditions with Superimposed Pulsating Flow
Authors: Zaki M. M. , Nirdosh I. , Sedahmed G. H.
Published: February 2011

Rates of mass transfer were measured at the inner surface of an annular duct by an electrochemical technique under developing flow conditions with superimposed pulsating flow. Variables like the frequency and amplitude of the pulsating flow, steady flow velocity, and annulus height were studied. The pulsating flow was found to enhance the rate of mass transfer by a factor ranging from 1.2 to 5.5 compared to the steady laminar flow value. The superimposed pulsating flow had only a minor effect on the rate of mass transfer under steady turbulent flow conditions. The pulsating flow reactor offers the advantage over steady flow annular reactor in that it can be operated at low flow rates to increase the residence time. The high residence time and high rate of mass transfer resulting from pulsation together increase the degree of conversion per pass as well as the reactor productivity.