bluuebunny/crossref_metadata_2025_split huggingface dataset:
Barrier Properties of Gastrointestinal Mucus to Nanoparticle Transport
Authors: Crater Jason S. , Carrier Rebecca L. 
Published: September 2010

AbstractGastrointestinal mucus, a complex network of highly branched glycoproteins and macromolecules, is the first barrier through which orally delivered drug and gene vectors must traverse. The diffusion of such vectors can be restricted by the high adhesivity and viscoelasticity of mucus. In this investigation, the barrier properties of gastrointestinal mucus to particle transport were explored using real‐time multiple particle tracking. The influence of surface chemistry on particle transport rates was examined using amine‐, carboxylate‐, and sulfate‐modified polystyrene nanoparticles. A strong dependence of particle mobility in gastrointestinal mucus on surface charge was observed, with anionic particles diffusing 20–30 times faster than cationic particles. Comparison of diffusion coefficients calculated for gastrointestinal mucus with significantly varying values previously reported in the literature for other mucus sources, including cervicovaginal mucus and cystic fibrosis sputum, highlight the dependence of mucus barrier properties on the anatomical source. A significant degree of transport rate heterogeneity was also observed in native gastrointestinal mucus, suggesting a highly heterogeneous distribution of pore sizes. Furthermore, the suitability of purified mucin as a model system for transport studies was assessed by comparing particle transport rates between native intestinal mucus and purified porcine gastric mucin. Particle transport rates were approximately threefold lower in native mucus compared to purified mucin for anionic particles, yet comparable for cationic particles. Differences between barrier properties of the purified mucin preparation and native mucus depended on specific carrier properties, indicating that the purified mucin preparation does not provide an accurate model system for native mucus.
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Construction of an Artificial Glutathione Peroxidase Active Site on Copolymer Vesicles
Authors: Yin Yanzhen , Huang Xin , Lv Chunyan , Wang Liang , Yu Shuangjiang , Luo Quan , Xu Jiayun , Liu Junqiu 
Published: September 2010

AbstractTo construct an efficient GPx mimic, a novel method for preparing polymer‐based vesicles carrying GPx‐active sites was developed. A series of block copolymers loaded with recognition and catalytic sites were synthesized based on polystyrene‐block‐poly[tri(ethylene glycol) methyl ether acrylate]s (PS‐PMEO3MAs). By altering the molar ratio of the functional copolymers, vesicles with GPx activity were obtained by self‐assembly of these functional copolymers through blending. The optimum GPx mimic constructed by the blending process exhibited high catalytic activity and acted as a real catalyst with typical saturation kinetics behavior. The method may be of benefit for designing other enzyme mimics and may cast a light on constructing other biologically related functional nanoparticles.
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Bioactive Scaffolds for Engineering Vascularized Cardiac Tissues
Authors: Chiu Loraine L. Y. , Radisic Milica , Vunjak‐Novakovic Gordana 
Published: September 2010

AbstractFunctional vascularization is a key requirement for the development and function of most tissues, and most critically cardiac muscle. Rapid and irreversible loss of cardiomyocytes during cardiac infarction directly results from the lack of blood supply. Contractile cardiac grafts, engineered using cardiovascular cells in conjunction with biomaterial scaffolds, are an actively studied method for cardiac repair. In this article, we focus on biomaterial scaffolds designed to mediate the development and maturation of vascular networks, by immobilized growth factors. The interactive effects of multiple vasculogenic factors are discussed in the context of cardiac tissue engineering.magnified image
Tailoring Linear and Nonlinear Optical Properties of a Side‐Chain Liquid Crystalline Azo‐Polymethacrylate
Authors: Alicante Raquel , Cases Rafael , Villacampa Belén , Oriol Luis 
Published: September 2010

AbstractThe molecular orientation in a side‐chain liquid crystalline azopolymer with push–pull chromophores (Pol‐PZ‐CN) is studied by UV‐vis spectroscopy, refractive index and second harmonic generation measurements. Fresh films show homeotropic arrangement, but irradiation with polarized light induces “in‐plane” birefringence, which is enhanced by subsequent thermal annealing up to values as high as 0.34. The nonlinear response of Corona poled films with “in‐plane” anisotropy is governed by three independent NLO dij coefficients, evidencing symmetry different from the usual (C∞v). For irradiated films, stable values d31 = 1.4, d32 = 0.9 and d33 = 11 pm·V−1 are measured at 1.9 µm. A noticeable higher d31/d32 ratio is obtained for preirradiated and annealed films. The proposed two‐step method consisting of light irradiation and heating is an effective strategy to tailor the polar molecular orientation of nonlinear liquid crystalline azopolymers.
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Synthesis of π‐Conjugated Polymer Possessing Mercapto‐Substituted 1,3‐Butadiene‐1,4‐diyl Units by Reaction of Regioregular Organometallic Polymer Having Titanacyclopentadiene Moieties in the Main Chain
Authors: Nishiyama Hiroki , Tomita Ikuyoshi 
Published: September 2010

AbstractA π‐conjugated polymer having 1,4‐bismercapto‐substituted 1,3‐diene units in the main chain was prepared by the novel polymer reaction of a regioregular organometallic polymer having titanacyclopentadiene‐2,5‐diyls units with benzenesulfenyl chloride. The number‐average molecular weight and the molecular weight distribution of the polymer derived from 1,4‐diethynyl‐2,5‐di(2‐ethylhexyloxy)benzene were estimated to be 5 700 and 1.6, respectively, from the GPC analysis. The π‐conjugated character, photoluminescence behavior both in solid‐state and solutions, and the electron‐donating properties of the π‐conjugated polymer are discussed on the basis of its UV‐vis spectrum, photoluminescence spectrum, and CV analysis.
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Systems of Singular Differential Operators of Mixed Order and Applications to 1 ‐ Dimensional MHD Problems
Authors: Hardt Volker , Mennicken Reinhard , Naboko Serguei 
Published: September 2010

AbstractIn some weighted L2 vector space we study a symmetric semibounded operator IL'0 which is given by a 3 x 3 system of ordinary differential operators on an intervall [0, ro] with a singularity at r = 0 (see (0.1)). This system can be considered as a “smooth” perturbation of a more specific physical model describing the oscillations of plasma in an equilibrium configuration in a cylindrical domain (see (1.12)). This perturbation is smooth in the sense that in the system under study in comparison with the physical model only the smooth parts of the coefficients are changed conserving all types of singularities. It is the goal of this paper to construct a suitable selfadjoint extension IL of the symmetric operator IL'0 (and its closure IL0) and to determine the essential spectrum of this extension. The essential spectrum consists of two bands (which may overlap) if we exclude the singularities by considering the system on an interval (r1,ro] with 0 < r1 < ro. In the corresponding physical model these bands are called Alfén spectrum and slow magnetosonic spectrum. It is shown that the singularity in 0 generates additional components of the essential spectrum which under specific conditions, as in the case of the physical model, “disappear” in the two bands known from the “regular” case (r1, ro) with r1 → 0.
On the Remainders of Asymptotic Expansions of Solutions of Linear Differential Equations near Irregular Singular Points of Higher Rank
Authors: Hoeppner Reinhard , Schäfke Reinhard 
Published: September 2010

AbstractWe study linear ordinary differential equations near singular points of higher Poincaré rank r under the condition that the leading matrix has distinct eigenvalues. It is well known that there are fundamental systems of formal vector solutions and that in certain sectors, there are actual rolutions having those as asymptotic expansions.We study the corresponding remainders, in particular if the truncation point N and the independent variable z are coupled such that Nzr is approximately constant. We show that the remainders are exponentially small under this condition and how to choose the constant optimally. Furthermore, we obtain precise asymptotic expansions for these remainders.As corollaries, we obtain well known asymptotic expansions for the coefficients in the formal solutions and limit formulas for Stokes' multipliers.The method of proof only uses functions in the original z ‐ plane and its main tools are the Cauchy ‐Heine theorem and the saddle‐point method.
On Representations of Matrix Valued Nevanlinna Functions by u ‐ Resolvents
Authors: Kaltenbäck Michael , Woracek Harald 
Published: September 2010

AbstractWe show that every matrix valued generalized Nevanlinna function can be represented as a u‐resolvent of a certain selfadjoint relation acting in a Pontryagin space. The negative index of this Pontryagin space may be larger than the number of negative squares of the given function. The minimal index of negative squares which is needed to obtain such a representation is determined. In the case of scalar functions, the results presented give rise to some new classes of generalized Nevanlinna functions.
K ‐‐ Convex Operators and Walsh Type Norms
Authors: Hinrichs Aicke 
Published: September 2010

AbstractA celebrated result of G. Pisier states that the notions of B‐convexity and K‐convexity coincide for Banach spaces. We complement this in the setting of linear and bounded operators between Banach spaces. Our approach is local and even yields inequalities between gradations of K‐convexity norms and Walsh type norms of operators. Our method combines G. Pisier's original ideas and the main steps in the proof of the Beurling‐Kato theorem on extensions of C0‐semigroups of operators to holomorphic semigroups with the technique of ideal norms.
Roles of Interlayers in Efficient Organic Photovoltaic Devices
Authors: Park Jong Hyeok , Lee Tae‐Woo , Chin Byung‐Doo , Wang Dong Hwan , Park O Ok 
Published: September 2010

AbstractThis review discusses interfacial layers in organic photovoltaic devices. The first part of the review focuses on the hole extraction layer, which is located between a positive electrode and an organic photoactive material. Strategies to improve hole extraction from the photoactive layer include incorporation of several different types of hole extraction layers, such as conductive polymeric materials, self‐assembled molecules and metal oxides, as well as surface treatment of the positive electrodes and the conductive polymeric layers. In the second part, we review recent research on interlayers that are located between a negative electrode and a photoactive layer to efficiently extract electrons from the active layer. These materials include titanium oxides, metal fluorides and other organic layers.
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Facile Synthesis of Double‐Shelled Polypyrrole Hollow Particles with a Structure Similar to That of a Thermal Bottle
Authors: Bai Meng‐Yi , Xia Younan 
Published: September 2010

AbstractPolystyrene (PS) hollow spheres containing a hole on the surface were used as templates to fabricate double‐shelled polypyrrole (PPy) hollow particles with a unique structure similar to that of a thermal bottle. Thanks to the hole on the surface, the monomer and initiator could easily and quickly diffuse into the interior of the PS hollow sphere to generate uniform PPy coatings on both the inner and outer surfaces of the hollow template. When the PS template was selectively removed with tetrahydrofuran, we obtained a double‐shelled hollow particle with a structure resembling that of a thermal bottle. We also demonstrated that the morphology and porosity of the resultant PPy coatings could be manipulated and fine‐tuned by adjusting at least three parameters: the concentration of monomer, the polymerization time, and the addition of poly(vinyl pyrrolidone).
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Homogeneous Phase Copolymerizations of Vinylidene Fluoride and Hexafluoropropene in Supercritical Carbon Dioxide
Authors: Möller Eléonore , Beuermann Sabine 
Published: September 2010

AbstractCopolymerizations of vinylidene fluoride (VDF) and hexafluoropropene (HFP) were carried out in homogeneous phase with supercritical carbon dioxide up to complete VDF conversion using conventional peroxide initiators. The HFP monomer feed ratios, fHFP, were varied between 0.65 and 0.20. Depending on fHFP amorphous or semi‐crystalline copolymers were obtained. fHFP also determines the minimum pressure required to allow for homogeneous phase reactions. For example, HFP‐rich copolymerizations in 70 wt.‐% CO2 at 100 °C require a pressure of around 500 bar. Further, bulk copolymerizations in homogenous phase were feasible for fHFP = 0.65 at 900 bar up to complete VDF conversion. Copolymerizations in the presence of perfluorinated hexyl iodide carried out at 75 °C gave access to low dispersity polymers. Due to homogeneous phase conditions the use of any surfactants or fluorinated cosolvent is avoided.
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An experimental study on the early stages of gas‐phase olefin polymerizations using supported Ziegler–Natta and metallocene catalysts
Authors: Machado Fabricio , Lima Enrique Luis , Pinto José Carlos , McKenna Timothy F. 
Published: September 2010

AbstractThe initial stages of gas‐phase polymerizations of propylene and ethylene are analyzed using a fixed bed stopped flow reactor. The very early development of particle morphology and polymer properties is analyzed for three different commercial catalyst systems: MgCl2‐ and SiO2‐supported Ziegler–Natta and SiO2‐supported metallocene. It is shown that, depending on the operating conditions, distinct nonuniform catalyst fragmentation patterns can develop, confirming different scenarios described by published fragmentation models. In addition, it is shown that the molecular weight distributions and polymer yields obtained during the very early stages of the polymerization suggest the existence of significant temperature gradients inside the growing polymer particles. Finally, it is shown that the ratio of catalyst to glass beads in the bed can have a pronounced effect on the evolution of the polymerization reaction. This can be interpreted in terms of the significant temperature difference between the polymer particles and the gaseous monomer stream. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers
Synthesis and properties of mesogen‐jacketed liquid crystalline polymers containing bistolane mesogen
Authors: Zhang Zhen Lin , Zhang Lan Ying , Shen Zhi Hao , Xing Guang Zhong , Fan Xing He , Zhou Qi Feng 
Published: September 2010

AbstractOn the basis of the concept of mesogen‐jacketed liquid crystalline polymers, a series of new methacrylate monomers, (2,5‐bis[2‐(4′‐alkoxyphenyl) ethynyl] benzyl methacrylate (MACn, n = 4, 6, 8, 10, and 12) and 2,5‐bis[2‐(6′‐decanoxynaphthyl) ethynyl] benzyl methacrylate (MANC10), and their polymers, PMACn (n = 4, 6, 8, 10, and 12) and PMANC10 were synthesized. The bistolane mesogen with large π‐electron conjugation were side‐attached to the polymer backbone via short linkages. Various characterization techniques such as differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized light microscopy were used to study their mesomorphic phase behavior. The polymer PMACn with shorter flexible substituents (n = 4) forms the columnar nematic (ϕN) phase, but other polymers with longer flexible tails (n = 6, 8, 10, and 12) can develop into a smetic A (SA) phase instead of a ϕN phase. The PMANC10 containing naphthyl can also form a well‐defined SA phase. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Well‐defined amphiphilic poly(p‐dioxanone)‐grafted poly(vinyl alcohol) copolymers: Synthesis and micellization
Authors: Wu Gang , Chen Si‐Chong , Zhan Qi , Wang Yu‐Zhong 
Published: September 2010

AbstractA series of amphiphilic biodegradable and biocompatible poly(p‐dioxanone)‐grafted poly(vinyl alcohol) (PVA) copolymers with well‐defined structure were obtained by a three‐step synthesis based on the “grafting from” concept. The first step (protection step), called the partial silylation of PVA hydroxyl groups, was accomplished by 1,1,1,3,3,3‐hexamethyldisilazane and catalyst chlorotrimethylsilane in dimethyl sulfoxide using THF as cosolvent. The second step was the ring‐opening polymerization of p‐dioxanone (PDO) initiated from the remaining OH groups of the partially silylated PVA. Finally, a deprotection step was followed: the silylether group was deprotected easily under very mild conditions. The synthetic conditions of the first two steps were investigated, and the structures of polymers formed in each step were characterized by various analytical methods. The results showed that the molecular structure of the PVA‐g‐PPDO could be controlled easily by the degree of silylation and the feed ratio. In addition, the micellization of amphiphilic PVA‐g‐PPDO copolymers in water was proved by fluorescence spectra and dynamic light scattering, and the relationship between structural parameters of copolymers and micellar properties was studied preliminarily. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Synthesis and applications of low‐bandgap conjugated polymers containing phenothiazine donor and various benzodiazole acceptors for polymer solar cells
Authors: Padhy Harihara , Huang Jen‐Hsien , Sahu Duryodhan , Patra Dhananjaya , Kekuda Dhananjay , Chu Chih‐Wei , Lin Hong‐Cheu 
Published: September 2010

AbstractA series of soluble donor‐acceptor conjugated polymers comprising of phenothiazine donor and various benzodiazole acceptors (i.e., benzothiadiazole, benzoselenodiazole, and benzoxadiazole) sandwiched between hexyl‐thiophene linkers were designed, synthesized, and used for the fabrication of polymer solar cells (PSC). The effects of the benzodiazole acceptors on the thermal, optical, electrochemical, and photovoltaic properties of these low‐bandgap (LBG) polymers were investigated. These LBG polymers possessed large molecular weight (Mn) in the range of 3.85−5.13 × 104 with high thermal decomposition temperatures, which demonstrated broad absorption in the region of 300−750 nm with optical bandgaps of 1.80−1.93 eV. Both the HOMO energy level (−5.38 to −5.47 eV) and LUMO energy level (−3.47 to −3.60 eV) of the LBG polymers were within the desirable range of ideal energy level. Under 100 mW/cm2 of AM 1.5 white‐light illumination, bulk heterojunction PSC devices containing an active layer of electron donor polymers mixed with electron acceptor [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) or [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) in different weight ratios were investigated. The best performance of the PSC device was obtained by using polymer PP6DHTBT as an electron donor and PC71BM as an acceptor in the weight ratio of 1:4, and a power conversion efficiency value of 1.20%, an open‐circuit voltage (Voc) value of 0.75 V, a short‐circuit current (Jsc) value of 4.60 mA/cm2, and a fill factor (FF) value of 35.0% were achieved. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Efficient gel‐type electrolyte with bismaleimide via in situ low temperature polymerization in dye‐sensitized solar cells
Authors: Chen Jian‐Ging , Liu Ken‐Yen , Chen Chia‐Yuan , Lin Chia‐Yu , Huang Kuan‐Chieh , Lai Yi‐Hsuan , Wu Chun‐Guey , Lin King‐Fu , Ho Kuo‐Chuan 
Published: September 2010

AbstractThis study reports the characteristics of gel‐type dye‐sensitized solar cells (DSSCs), fabricated with gel‐type electrolyte containing poly‐1,1′‐(methylenedi‐4,1‐phenylene)bismaleimide (PBMI), or poly‐1,1′‐(3,3′‐dimethyl‐1,1′‐biphenyl‐4,4′‐diyl)bismaleimide (PDBBMI), or poly‐N,N′‐(4‐methyl‐1,3‐phenylene)bismaleimide (PMPBMI), prepared by in situ polymerization of the corresponding monomer without an initiator at 30 °C. Incorporating 0.3 wt % content of exfoliated alkyl‐modified nanomica (EAMNM) into PBMI‐gelled electrolyte leads to higher short‐circuit current density (Jsc = 17.14 mA cm−2) and efficiency (η = 7.02%) than that of neat PBMI‐gel electrolyte (Jsc = 15.32 mA cm−2, η = 6.41%). Incorporating 0.3 wt % EAMNM into PBMI‐gelled electrolyte results in remarkably stable device performance under continuous light soaking under one sun (100 mW cm−2) at 55 °C. The efficiency of DSSCs based on PBMI/0.3 wt % EAMNM‐gelled electrolyte drops by only 1.7% (η = 6.93%) after 500 h of continuous light soaking. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Plasma Activation and Self Bonding of PEEK for the Use in the Encapsulation of Medical Implants
Authors: Awaja Firas , Zhang Shengnan , James Natalie , McKenzie David R. 
Published: September 2010

AbstractPolyether ether ketone (PEEK) and its composites have emerged as one of the main candidate materials for replacing titanium and its alloys for the encapsulating components of medical implants. PEEK, however, is a difficult material to bond without the use of adhesion promoting agents. Experiments based on the central composite rotatable design (CCRD) were used to find an optimum plasma surface modification treatment. X‐ray photoelectron spectrometry (XPS), contact angle measurements and scanning electron microscopy (SEM) were used to provide surface molecular and thermodynamic information. Higher self bond strength of PEEK was found to correlate with higher relative oxygen concentration and total surface energy. Mechanisms for the autohesive bond formation were developed based on the oxidation of the surface.
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Pressurization of fixed roof storage tanks due to external fires
Authors: Fouillen Fabien , Duplantier Stéphane 
Published: September 2010

AbstractWhen a fixed roof storage tank is surrounded by a pool fire, and when the vents are not correctly dimensioned, the inside pressure can raise until the mechanical limits of the structure. The aim of this study is to develop a tool that will allow to follow the variations of the pressure and temperature in the gas phase, as a function of the size of the vent. This will help the sizing of new tank's vents or evaluating the risk of already build structures. The model also gives the temperature's distribution in the liquid phase, at each time step. In case of undersized vents, this information will be convenient to describe the phenomenological aspect of the accident after the rupture of the tank, i.e., to qualify and quantify the fire ball generated and its effect on persons and structures. Currently, if few analytical models exist to quantify the fire ball and its effects after the rupture, none are able to describe with accuracy the prerupture phenomena. The tool developed takes into account the two phases of the accident and allows to study complete and consistent scenarii. © 2010 American Institute of Chemical Engineers Process Saf Prog, 2011
Using hazards assessment to prevent loss of containment
Authors: Dharmavaram S. , Klein James A. 
Published: September 2010

AbstractPreventing loss of containment of materials and/or energy is a primary goal of industrial Process Safety Management programs. A thorough understanding of the hazards, identification of a complete range of failure events, detailed analysis of the consequences of failure events, and the analysis of process risks accounting for all the safeguards can help significantly in preventing and mitigating loss of containment incidents. In this article, additional details are provided on hazard assessment approaches, consequence analysis of potential events, and risk analysis for minimizing risks. © 2010 American Institute of Chemical Engineers Process Saf Prog, 2010