bluuebunny/crossref_metadata_2025 huggingface dataset:
Neural Stem Cell Transplantation in Mouse Brain
Authors: Lee Jean‐Pyo , McKercher Scott , Muller Franz‐Josef , Snyder Evan Y.
Published: January 2008

Neural stem cells (NSCs) are the most primordial, least committed cells of the nervous system, and transplantation of these multipotent cells holds the promise of regenerative therapy for many central nervous system (CNS) diseases. This unit describes methods for NSC transplantation into neonatal mouse pups, embryonic mouse brain, and adult mouse brain. A description of options for detection of labeled donor cells in engrafted mouse brain is provided along with an example protocol for detecting lacZ‐expressing cells in situ. Also included is a protocol for preparing NSCs for transplantation. Curr. Protoc. Neurosci. 42:3.10.1‐3.10.23. © 2008 by John Wiley & Sons, Inc.
Nulling Signal of a Slice, Slice Select Profile, and Radiofrequency Power
Authors: Cheng Yu‐Chung Norman , Haacke E. Mark
Published: January 2008

This unit discusses nulling of remaining signal from a RF pulse prior to the next RF pulse. This is to avoid mixing leftover signal with the signal generated from the next RF pulse. The slice select profile is also discussed in detail. The power of the RF pulse and its limit imposed by the Food and Drug Administration (FDA) is also discussed.
Overview of DNA Sequencing Strategies
Authors: Shendure Jay A. , Porreca Gregory J. , Church George M.
Published: January 2008

Efficient and cost‐effective DNA sequencing technologies have been, and may continue to be, critical to the progress of molecular biology. This overview of DNA sequencing strategies provides a high‐level review of six distinct approaches to DNA sequencing: (a) dideoxy sequencing; (b) cyclic array sequencing; (c) sequencing‐by‐hybridization; (d) microelectrophoresis; (e) mass spectrometry; and (f) nanopore sequencing. The primary focus is on dideoxy sequencing, which has been the dominant technology since 1977, and on cyclic array strategies, for which several competitive implementations have been developed since 2005. Because the field of DNA sequencing is changing rapidly, this unit represents a snapshot of this particular moment. Curr. Protoc. Mol. Biol. 81:7.1.1‐7.1.11. © 2008 by John Wiley & Sons, Inc.
Transfection of Cultured Eukaryotic Cells Using Cationic Lipid Reagents
Authors: Hawley‐Nelson Pamela , Ciccarone Valentina , Moore Meredith L.
Published: January 2008

The development of high‐efficiency methods for the introduction of functional genetic material into eukaryotic cells using cationic lipids has accelerated biological research in the studies of gene expression, control of cell growth, and cell lineage. Transfection mediated by cationic lipids is commonly used in industrial protein production as well as in some clinical gene therapy protocols. This unit describes how to perform transfection of adherent and suspension cells, insect cells, and RNA transfection using cationic lipid reagents. Curr. Protoc. Mol. Biol. 81:9.4.1‐9.4.17. © 2008 by John Wiley & Sons, Inc.
Analysis of Small Endogenous RNAs
Authors: Lau Nelson C.
Published: January 2008

Eukaryotic cells express small noncoding RNAs to silence target genes or regulate chromatin domains. MicroRNAs (miRNA) are endogenous small RNAs that are thought to each regulate multiple mRNA targets. To gain a deeper understanding of processes regulated by small noncoding RNAs, techniques are required to identify and detect them. This unit describes standard laboratory methods for and comments about high‐throughput technologies for the identification and detection of small RNAs. This unit also outlines a cell‐based reporter gene assay for assessing the regulatory potential of a microRNA on a candidate mRNA target. Curr. Protoc. Mol. Biol. 81:26.7.1‐26.7.15. © 2008 by John Wiley & Sons, Inc.
Human Hematopoietic Cell Culture, Transduction, and Analyses
Authors: Bonde Jesper , Wirthlin Louisa , B. Kohn Donald , A. Nolta Jan
Published: January 2008

This unit provides methods for introducing genes into human hematopoietic progenitor cells. The Basic Protocol describes isolation of CD34+ cells, transduction of these cells with a retroviral vector on fibronectin‐coated plates, assaying the efficiency of transduction, and establishing long‐term cultures. Support protocols describe methods for maintenance of vector‐producing fibroblasts (VPF) and supernatant collection from these cells, screening medium components for the ability to support hematopoietic cell growth, and establishing colonies from long‐term cultures. Other protocols provide PCR‐based methods to analyze individual colonies for transduction, methods to analyze cells harvested from long‐term cultures, and procedures for freezing and thawing of hematopoietic cells. Curr. Protoc. Hum. Genet. 56:13.7.1‐13.7.31. © 2008 by John Wiley & Sons, Inc.
Influence of Molecular Dipoles on the Photoluminescence and Electroluminescence of Dipolar Spirobifluorenes
Authors: Chiang C.‐L. , Tseng S.‐M. , Chen C.‐T. , Hsu C.‐P. , Shu C.‐F.
Published: January 2008

This Full Paper investigates a series of strongly fluorescent donor–acceptor‐substituted spirobifluorene compounds, red 2‐diphenylamino‐7‐(2,2‐dicyanovinyl)‐9,9′‐spirobifluorene (DCV), green 2‐diphenylamino‐9,9′‐spirobifluorene7‐carxoxaldehyde (CHO), and blue 2‐diphenylamino‐7‐(2,2‐diphenylvinyl)‐9,9′‐spirobifluorene (DPV), together with their spiro‐linked “dimeric” analogs, 2DCV, 2,2′‐bis(diphenylamino)‐9,9′‐spirobifluorene‐7,7′‐dicarboxaldehyde (2CHO), and 2,2′‐bis(diphenylamino)‐7,7′‐bis(2,2‐diphenylvinyl)‐9,9′‐spirobifluorene (2DPV), respectively. The emission optical density and, hence, the intensity of photoluminescence (PL) or electroluminescence (EL) of the “dimeric” analogs is presumed to increase, which is beneficial for organic light‐emitting diode (OLED) applications. The physical properties, including the dipole moments obtained from quantum chemistry calculations, emission solvatochromism, fluorescence quantum yield (Φf) as well as the EL of these six spirobifluorene compounds have been examined in detail. We found that Φf as well as OLED performance (EL efficiency and intensity) of the strongly dipolar DCV decrease significantly in the “dimeric” analog 2DCV, but less so in the moderately dipolar CHO and 2CHO, and only slightly in the weakly dipolar DPV and 2DPV. This is parallel to the intramolecular dipole moment, which is large for 2DCV, medium for 2CHO, and very small for 2DPV. Here, we show for the first time systematically that the luminescence intensity is closely correlated with the local electric field induced by the molecular dipole. A strong electric field may facilitate radiationless decay channels with a charge‐transfer nature, leading to a high quenching rate. Consistent with this conclusion, which is derived from the red DCV/2DCV and green CHO/2CHO, our new blue fluorophore DPV with an essentially zero dipole moment has successfully achieved one of the best electrofluorescent blue OLEDs. At the same time, by doping the highly dipolar DCV into an isolated environment with the low‐polarity Alq3 as the host matrix, we obtained a very high performance of saturated yellow OLEDs as well, This is possibly due to the reduction of emission‐quenching dipoles from the neighboring molecules. Our results have provided an important insight in designing luminescent materials, as follows: molecular dipole moments should be kept at a low magnitude to avoid quenching induced by a strong local electric field in the chromophore.
Photorefractive Performance of Hyperstructured Cyclotriphosphazene Molecular Glasses containing Carbazole Moieties
Authors: Zhang L. , Shi J. , Jiang Z. W. , Huang M. M. , Chen Z. J. , Gong Q. H. , Cao S. K.
Published: January 2008

Two hyperstructured photorefractive (PR) molecular glasses (M1 and M2) with a cyclotriphosphazene core are synthesized via nucleophilic substitution and an azo‐coupling reaction. These molecules exhibit excellent solubility in common organic solvents and maintain a complete amorphous state in spite of their high glass‐transition temperature. The nonlinear optical effects, two‐beam coupling and four‐wave mixing, respectively, are used to prove the PR performance in the optically transparent films of M1 and M2 doped with 30 % N‐ethyl‐carbazole. With no external electric field, a gain coefficient of 102 cm–1 and diffraction efficiency of 24 % are obtained in the composite made from M1, and an even higher gain coefficient of 214 cm–1 and diffraction efficiency of 31 % are obtained in the composite made from M2 owing to its higher chromophore loading.
A Smart Light‐Controlled Carrier Switch in an Organic Light Emitting Device
Authors: Zhang Z. , Liu X. , Li Z. , Chen Z. , Zhao F. , Zhang F. , Tung C.‐H.
Published: January 2008

A real ON–OFF carrier switch based on a new ferrocenyl diarylethene compound (DTE‐FC) as the light‐sensitive and photoswitching layer in an organic light‐emitting device (OLED) with a multilayer sandwich structure has been prepared. This switch layer functions not only as a hole transporter but also as a good barrier block when needed, which arises from the light‐induced photochromic effect of the DTE‐FC. For the uncolored open‐ring form of DTE‐FC, no luminescence was observed despite the increase in applied voltage. On the contrary, for the colored photostationary state of DTE‐FC, which was obtained by irradiation with 365 nm light, the luminescence could be observed when the applied voltage reached 14.0 V and increased with applied voltage. Thus, the uncolored state corresponds to the OFF state of luminescence and the photostationary state corresponds to the ON state. The two states can be interconverted by control of the UV and visible light (>500 nm) irradiation.
Modeling Electron and Hole Transport in Fluoroarene‐Oligothiopene Semiconductors: Investigation of Geometric and Electronic Structure Properties
Authors: Koh S. E. , Risko C. , da Silva Filho D. A. , Kwon O. , Facchetti A. , Brédas J.‐L. , Marks T. J. , Ratner M. A.
Published: January 2008

A theoretical study using density functional theory is undertaken to gain insight into how the structural, electronic, and electron‐transfer characteristics of three Fluoroarene‐oligothiophene semiconductors influence the preferred transport of electrons versus holes in field‐effect transistor applications. The intermolecular electronic coupling interactions are analyzed through both a simplified energy‐splitting in dimer (ESID) model and as a function of the entire dimer Hamiltonian in order to understand the impact of site energy differences; our results indicate that these differences are generally negligible for the series and, hence, use of the ESID model is valid. In addition, we also investigate the reduction and oxidation processes to understand the magnitudes of the intramolecular reorganization energy for the charge‐hopping process and expected barrier heights for electron and hole injection into these materials. From the electronic coupling and intramolecular reorganization energies, estimates of the nearest‐neighbor electron‐transfer hopping rate constant for electrons are obtained. The ionization energetics suggest favored electron injection for the system with perfluoroarene groups at the end of the thiophene core, in agreement with experiments. The combined analyses of the electron‐transfer properties and ionization processes suggest possible ambipolar behavior for these materials under favorable device conditions.
Giant Chromatic Lipid/Polydiacetylene Vesicles for Detection and Visualization of Membrane Interactions
Authors: Pevzner A. , Kolusheva S. , Orynbayeva Z. , Jelinek R.
Published: January 2008

We present the construction of microscopic vesicular particles comprising phospholipids and polydiacetylene (PDA), a polymer with unique color and fluorescence properties. We show that the vesicle‐embedded PDA domains function as chromatic reporters of membrane events, undergoing dramatic colorimetric and fluorescence transformations induced by interactions with membrane‐active species. In particular, the micrometer sizes of the giant vesicles facilitate their utilization for visual inspection of membrane events by conventional microscopy techniques. The morphology, size, and chromatic properties of the vesicular aggregates depend upon the type of phospholipids and the molecular ratio between the phospholipids and diacetylene, indicating that the lipids and polymer form interdependent domains within the vesicles. The giant chromatic aggregates have been employed for detection and microscopic visualization of varied membrane processes, including lipid interactions of lipophilic drugs, binding of antimicrobial peptides, and membrane attachment by virus particles.
Nanocomposite Films of a Polyfluorene Copolymer and Carbazole– Thiol‐Capped Gold Nanoparticles: Electrochemical Crosslinking and Energy‐Transfer Properties
Authors: Taranekar P. , Huang C. , Fulghum T. M. , Baba A. , Jiang G. , Park J.‐Y. , Advincula R. C.
Published: January 2008

The preparation and properties of an electrochemically crosslinked Au nanoparticle/polyvinylcarbazole (PVK)/polyfluorene (PFC) nanocomposite film is described. Blends of the blue‐light emitting PFC, PVK, and the 11‐(9H‐carbazol‐9‐yl)‐undecane‐1‐thiol‐capped Au nanoparticles (CBZ‐S‐Au) were prepared as thin films by spin‐coating and subsequent crosslinking by cyclic voltammetry (CV). The electrochemical properties are then evaluated on the basis of the redox behavior (reversibility) and electron‐transport properties of the films. They are further characterized by UV‐vis spectroscopy, photoluminescence spectroscopy, and atomic force microscopy (AFM). The large differences in photoluminescence properties of the CBZ‐S‐Au/PFCVK crosslinked copolymer composite film compared to the PFCVK polymer alone result in an efficient energy‐transfer system, in which the excimer peak is almost totally quenched. This indicates a compatible match between the absorbance of the Au plasmons and the emission of the excimer energy trap from PF polymers. Furthermore, electrochemical crosslinking enhances this match both by shifting the absorbance to greater overlap and decreasing the Förster distance between the Au nanoparticle and the PFCVK polymer chains.
Cover Picture: Self‐Organization of Ink‐jet‐Printed Triisopropylsilylethynyl Pentacene via Evaporation‐Induced Flows in a Drying Droplet (Adv. Funct. Mater. 2/2008)
Authors: Lim J. A. , Lee W. H. , Lee H. S. , Lee J. H. , Park Y. D. , Cho K.
Published: January 2008

Charge carrier transport in organic electronic devices is influenced by the crystalline microstructure and morphology of the organic semiconductor film. Evaporation behavior during drying plays a vital role in controlling the film morphology and the distribution of solute in inkjet‐printed films. On p. 229, Kilwon Cho and co‐workers demonstrate the influence of the evaporation‐induced flow in a single droplet on the crystalline microstructure and film morphology of inkjet‐printed 6,13‐bis((triisopropylsilylethynyl) pentacene. The results provide an excellent method for direct‐write fabrication of high‐performance organic electronics.

We have demonstrated the influence of evaporation‐induced flow in a single droplet on the crystalline microstructure and film morphology of an ink‐jet‐printed organic semiconductor, 6,13‐bis((triisopropylsilylethynyl) pentacene (TIPS_PEN), by varying the composition of the solvent mixture. The ringlike deposits induced by outward convective flow in the droplets have a randomly oriented crystalline structure. The addition of dichlorobenzene as an evaporation control agent results in a homogeneous film morphology due to slow evaporation, but the molecular orientation of the film is undesirable in that it is similar to that of the ring‐deposited films. However, self‐aligned TIPS_PEN crystals with highly ordered crystalline structures were successfully produced when dodecane was added. Dodecane has a high boiling point and a low surface tension, and its addition to the solvent results in a recirculation flow in the droplets that is induced by a Marangoni flow (surface‐tension‐driven flow), which arises during the drying processes in the direction opposite to the convective flow. The field‐effect transistors fabricated with these self‐aligned crystals via ink‐jet printing exhibit significantly improved performance with an average effective field‐effect mobility of 0.12 cm2 V–1 s–1. These results demonstrate that with the choice of appropriate solvent ink‐jet printing is an excellent method for the production of organic semiconductor films with uniform morphology and desired molecular orientation for the direct‐write fabrication of high‐performance organic electronics.
Bimaterial Microcantilevers as a Hybrid Sensing Platform
Authors: Singamaneni S. , LeMieux M. C. , Lang H. P. , Gerber C. , Lam Y. , Zauscher S. , Datskos P. G. , Lavrik N. V. , Jiang H. , Naik R. R. , Bunning T. J. , Tsukruk V. V.
Published: January 2008

Microcantilevers, one of the most common MEMS structures, have been introduced as a novel sensing paradigm nearly a decade ago. Ever since, the technology has emerged to find important applications in chemical, biological and physical sensing areas. Today the technology stands at the verge of providing the next generation of sophisticated sensors (such as artificial nose, artificial tongue) with extremely high sensitivity and miniature size. The article provides an overview of the modes of detection, theory behind the transduction mechanisms, materials employed as active layers, and some of the important applications. Emphasizing the material design aspects, the review underscores the most important findings, current trends, key challenges and future directions of the microcantilever based sensor technology.
The iodide iodate method to characterize microstructured mixing devices
Authors: Kölbl A. , Kraut M. , Schubert K.
Published: January 2008

The iodide iodate method (also known as Villermaux method) was used to characterize multilamination‐type mixers, manufactured at the Institute for Micro Process Engineering of the Forschungszentrum Karlsruhe. Mixing sensitive results were obtained using different reactant concentrations. It is shown that the experimentally obtained data cannot be treated as quantitative data in sense of a “mixing quality.” © 2008 American Institute of Chemical Engineers AIChE J, 2008
The effects of manifold flow on mass transport in electrochemical filter‐press reactors
Authors: Frías‐Ferrer Á. , González‐García J. , Sáez V. , de León C. Ponce , Walsh F. C.
Published: January 2008

The mass transport rates to planar electrodes, in a series of electrochemical laboratory filter‐press reactors were measured to quantify the effects of the inlet and outlet design manifolds on the fluid flow. In small reactors, entrance/exit effects are especially important due to the localized generation of fluid recirculation zones, which affect the overall rate of mass transport. Limiting current data, the cathodic reduction of Cu(II) ions on a copper surface (under convective‐diffusion control) were used to measure global mass transport coefficients. The data are compared with those from a well‐characterized laboratory cell, the FM01‐LC electrolyzer. The importance of manifold design in small‐scale electrochemical reactors is discussed, and several dimensionless parameters are used to characterize the manifold geometry. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Polymerization of acrylonitrile initiated by cerium (IV)‐oxalic acid redox system: A kinetic study
Authors: Demappa T. , Mahadevaiah
Published: January 2008

The kinetics of aqueous polymerization of Acrylonitrile initiated by the Cerium (IV)‐Oxalic acid redox system in Sulfuric acid medium has studied under nitrogen atmosphere in the temperature range of 25–50°C. The rate of polymerization (Rp) and the disappearance of Cerium (IV) have been measured. The water‐miscible organic solvents and inorganic salts were depressed both the rate and the conversion. The effects of ionic strength, effects of surfactant have been investigated. The temperature dependence of the rate was studied and the activation parameters were computed using Arrhenius and Eyring plots. A mechanism consistent with the experimental data, involving Ce(IV)–Oxalic acid complexation that generates free radical was suggested. The chain termination step of the polymerization reaction was determined. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Sulfonated poly(ether imide) and poly(ether sulfone) blends for direct methanol fuel cells. II. Membrane preparation and performance
Authors: Shu Yao‐Chi , Chuang Fu‐Sheng , Tsen Wen‐Chin , Chow Jing‐Dong , Gong Chunli , Wen Sheng
Published: January 2008

This study describes the preparation and characterization of new ionomer blend membranes containing sulfonated poly(ether imide) (SPEI) and poly(ether sulfone) (PES). Thermogravimetric analysis indicated that the obtained blend membranes were more thermally stable than the parent SPEI. As the PES content increased, the extent of membrane swelling by water decreased, and the oxidative stability was significantly increased by the specific interactions between PES and the sulfonic acid groups. Under both dry and wet conditions, the tensile strength of all the blend membranes was larger than that of the pure SPEI membrane and Nafion 112 because of the reinforcing effect of PES. Scanning electron microscopy and atomic force microscopy indicated that the blend membranes became more compact as the PES content increased, and this reduced the methanol diffusion. The blend membranes with PES contents below 50% showed adequate proton conductivity. The lower permeability of the blend membranes compared with the Nafion 112 membrane resulted in higher methanol resistance. This considerable reduction in methanol crossover revealed the feasibility of the blend membranes as promising electrolytes for direct methanol fuel cells. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
The preparation and electrical conductivity of polyacrylamide/graphite conducting hydrogel
Authors: Tang Qunwei , Lin Jianming , Wu Jihuai
Published: January 2008

Polyacrylamide/graphite superabsorbent composite was synthesized by free radical polymerization of acrylamide monomer using N,N′‐methylene‐bis‐acrylamide as crosslinker, potassium persulfate as initiator, and graphite as functional filler. On the basis of the superabsorbent composite, a hydrogel with a conductivity of 0.86 mS cm−1 was obtained. The preparation conditions were optimized. The influence of crosslinker, initiator, monomer, graphite, water absorbency, and temperature on the conductivity of the hydrogel was investigated, an adsorbed network structure model for polyacrylamide/graphite conducting hydrogel was purposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Investigation on the crystallization behavior of poly(ether ether ketone)/poly(phenylene sulfide) blends
Authors: Zhang Ri‐Chao , Xu Yi , Lu Zhongyuan , Min Min , Gao Yong , Huang Yigang , Lu Ai
Published: January 2008

The morphology of nonisothermally crystallized poly(phenylene sulfide) (PPS) and its blend with poly (ether ether ketone) (PEEK) have been observed by polarized optical microscope (POM) equipped with a hot stage. The nonisothermal crystallization behavior of PPS and PEEK/PPS blend has also been investigated by differential scanning calorimetry (DSC). The maximum crystallization temperature for PEEK/PPS blend is about 15°C higher than that of neat PPS, and the crystallization rate, characterized by half crystallization time, of the PEEK/PPS blend is also higher than that of the neat PPS. These results indicate that the PEEK acts as an effective nucleation agent and greatly accelerates the crystallization rate of PPS. The Ozawa model was used to analyze the nonisothermal crystallization kinetics of PPS and its blends. The Avrami exponent values of neat PPS are higher than that of its blend, which shows that the presence of PEEK changed the nucleation type of PPS from homogeneous nucleation to heterogeneous nucleation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
New poly(phenylene oxide)/polystyrene blend nanocomposites with clay: Intercalation, thermal and mechanical properties
Authors: Tiwari Rajkiran R. , Khilar Kartic C. , Natarajan Upendra
Published: January 2008

We present the first study and results on the preparation and characterization of montmorillonite clay filler based polymer blend nanocomposites of the miscible poly(phenylene oxide)/polystyrene blend. Intercalated nanocomposites, prepared by a melt‐processing method with 2–6 wt % commercially available organically modified sodium montmorillonite, have been characterized with wide‐angle X‐ray diffraction, transmission electron microscopy analysis, thermal analysis (thermogravimetric analysis and differential scanning calorimetry), and mechanical tensile tests. We show that nanocomposites can be successfully prepared in a batch mixer at temperatures much below the conditions conventionally used for this blend without organic degradation. Thermal stability is enhanced by nanoscale hybrid formation. The level of intercalation (change in the d‐spacing) does not change with the clay loading. Better dispersion of clay in the blend matrix has been observed at a low level of clay content. The nanocomposites show improved tensile modulus (by 31%) in comparison to the blend, whereas the tensile strength (stress at break) and elongation decrease in the presence of the filler with an increase in the clay loading. The Halpin–Tsai model is able to predict the modulus of the nanocomposites in very good agreement with the experimental data. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Facile size‐controllable syntheses of highly monodisperse polystyrene nano‐ and microspheres by polyvinylpyrrolidone‐mediated emulsifier‐free emulsion polymerization
Authors: Du Xin , He Junhui
Published: January 2008

A facile emulsifier‐free emulsion polymerization approach was developed to fabricate highly monodisperse polystyrene (PS) spheres using potassium persulfate as the initiator and polyvinylpyrrolidone (PVP) as a stabilizer, respectively. It was found that the size of monodisperse PS spheres tends to decrease with increase of the PVP concentration, and the size of monodisperse PS spheres could be easily controlled in a wide range from 200 to 1500 nm simply by adjusting the concentration of PVP. The increase of monomer concentration led to the increase in size of monodisperse PS spheres. In contrast, the increase of initiator concentration resulted in the decrease in size of monodisperse PS spheres. These concentration changes, however, did not significantly affect the size distributions of PS spheres. It was also found that the size of monodisperse PS spheres obtained by adding the initiator at room temperature was larger than that by adding the initiator at 70°C, and the existence of inhibitor resulted in smaller PS spheres. The mechanisms in which the above factors influence the size and size distribution were discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Evaluation of solubility parameters for nonvolatile branched hydrocarbons by inverse gas chromatography
Authors: Sreekanth T. V. M. , Reddy K. S.
Published: January 2008

Flory‐Huggins interaction parameters determined by inverse gas chromatographic (IGC) technique have been used for the estimation of solubility parameters of nonvolatile branched hydrocarbon solvents. A family of isosteric branched hydrocarbons consists of one apolar stationary phase, 19,24‐dioctadecyldotetracontane (C78), and four polar stationary solvents formed by replacing one of the CH3 groups of C78 by OH (POH), CN (PCN), SH (PSH), CF3 (MTF), and two other polar solvents formed by replacing four CH3 groups of C78 with four CF3 (TTF) and OCH3 (TMO) are investigated. The three‐dimensional Hansen solubility parameters of the solvents have been estimated following the approaches of Voelkel and the method of Huang at five different temperatures. In the three components estimated by Voelkel method, the dispersion component is decreasing rapidly, whereas the polar, and hydrogen bonding components of the solubility parameters are increasing with temperature. In the components of solubility parameter estimated by Huang method, the dispersion and hydrogen bonding components are slowly decreasing with temperature, however, the polar components are almost constant with temperature. The components of solubility parameters for different solvents have been discussed in terms of solvent polarity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Viscoelastic properties of polyarylene ether nitriles/thermotropic liquid crystalline polymer blend
Authors: Wu Defeng , Zhang Yisheng , Wu Lanfeng , Jin Lifeng , Zhang Ming , Zhou Weidong , Yan Changhao
Published: January 2008

Polyarylene ether nitriles (PEN)/thermotropic liquid crystalline polymer (TLCP) blend was prepared via melt mixing. The immiscible phase morphologies, linear and nonlinear, as well as transient viscoelastic properties of the blend were studied using SEM, rheometer, and DMA. The linear dynamic viscoelastic behavior of the blend shows temperature dependence due to further evolution of the immiscible morphology and, as a result, the principle of time‐temperature superposition (TTS) is invalid. In the steady shear flow, the discrete TLCP phase is difficult to be broken up because of the high viscosity ratio of the blend systems, while is easy to be coarsened and followed by elongation, and finally, to form fibrous morphology at high TLCP content and high shear level. During this morphological evolution process, the transient stress response presents step increase and nonzero residual relaxation behavior, leading to increase of the dynamic viscoelastic responses after steady preshear. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Anionic polymerization and properties of graft copolymers consisting of alternating styrene/maleimide copolymer main chains and polyamide 6 grafts
Authors: Xu Wei , Liu Yao‐Chi , Xiong Yuan‐Qin , Miao Yan‐Ru , Xu Wei‐Jian
Published: January 2008

This article is focused on the synthesis of a new type of graft PA6, which contained alternating styrene/maleimide copolymer main chains and PA6 grafts, by anionic polymerization. The preprepared styrene/maleimide copolymers with acylated caprolactam (ACL) pendants were used as macroactivators for the polymerization of molten ε‐caprolactam (CL). Because of the low activating energy for the initial nucleophilic attack of CL anion on the N‐ACL, the polymerization took place in a few minutes. The macroactivators were characterized by 1H‐NMR. And the thermal properties, dimensional stability, crystallinity, and solvent resistance ability of the graft PA6 were studied, using DSC, TGA, XRD, water absorption measurement, and solubility experiment. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Solubility of carbon dioxide and cosolvents in a photoresist polymer
Authors: Balashova Ida M. , Russell Marc C. , Danner Ronald P. , Duda J. Larry
Published: January 2008

Solubility and diffusivity of cosolvents and carbon dioxide in a photoresist polymer have been measured below the glass transition temperature bythe inverse gas chromatography and static capsule methods over a temperature range of 75–100°C and pressures up to 7000 kPa. The results showed that presence of even low pressures of CO2 increased the solubility and diffusivity of the cosolvents studied. Experiments in which exposure of the polymer to CO2 was cycled on and off indicated that the free volume introduced by the CO2 persisted in the polymer for a significant time after removal of the CO2. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Crystallization behavior of a thermoplastic polyimide derived from 3,3′,4,4′‐oxydiphthalic dianhydride and 4,4′‐oxydianiline
Authors: Zhao Guiyan , Zhang Min , Men Yongfeng , Ding Mengxian , Jiang Wei
Published: January 2008

Nonisothermal and isothermal crystallization kinetics of an aromatic thermoplastic polyimide derived from 3,3′,4,4′‐oxydiphthalic dianhydride and 4,4′‐oxydianiline have been investigated by means of differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction. The results for nonisothermal crystallization study showed that a weak melting peak appeared during the first heating process, whereas no crystallization peak appeared in the DSC curve during the subsequent cooling process. On the other hand, the study for the isothermal crystallization in the temperature range of 260–330°C showed that a new exothermic peak appeared at lower temperature for the samples crystallized for 100 min at 300°C. Moreover, the results indicated that the crystallization behaviors were largely affected by the crystallization temperature and crystallization time. During the annealing process, the melting enthalpy tended to increase with increasing annealing temperature and annealing time. More interesting was that two melting endotherms appeared when the annealing temperature was lower than 300°C. However, when the annealing temperature was higher than 330°C, only one melting endotherm appeared. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Surface modification of carbon fiber by redox‐induced graft polymerization of acrylic acid
Authors: Xu Zhiwei , Wu Xiaoqing , Sun Ying , Jiao Yanan , Li Jialu , Chen Li , Lu Liangsen
Published: January 2008

Carbon fibers were modified by graft polymerization with acrylic acid (AA) using KMnO4/H2SO4 redox‐induced system. The carbon fibers were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. After grafting, the absorbability of treated fibers might be enhanced and more pieces of tiny fragments stuck to the fiber surface. It was confirmed that grafting AA led to a remarkable increase in oxygen‐containing functional groups of fiber surface. An about twofold increase in retained surface carboxylic acid groups occurred. The adhesion between carbon fiber and epoxy matrix was inspected by interlaminar shear strength and SEM. It was noted that the functionalized grafting coating of fiber surface gave rise to a strong interfacial bond, with little debonding. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Intercalated clays from pentaerythritol stearate for use in polymer nanocomposites
Authors: Bartels J. , Beall G. W. , Grah M. , Jin K. , Speer D. , Yarbrough J.
Published: January 2008

Smectite clays treated with quaternary ammonium salts have been utilized for decades in paints, greases, cosmetics, and personal care products as rheological modifiers. They have also been used in industrial wastewater treatment extensively. In more recent times these surface modified clays have demonstrated benefits in polymer/clay nanocomposites. The use of quaternary ammonium modifiers limits the usefulness of these composites in food packaging because they are not approved for direct food contact. It would be advantageous to have surface modifying chemicals acceptable for direct food contact in these composites. This article reports research conducted on a promising surface modifier pentaerythritol stearate (PS), which is approved by the FDA for inclusion in food as a preservative. The surface modification of montmorillonite with PS is reported in detail as well as the production of nanocomposites with selected polymers made with the modified clay. Molecular modeling and purification of commercial PS samples indicate that the mono‐ and diesters are the critical surface modifiers, although the as received commercial material works well in forming intercalated clay complexes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Increased Dosage of DYRK1A and Brain Volumetric Alterations in a YAC Model of Partial Trisomy 21
Authors: Sebrié Catherine , Chabert Caroline , Ledru Aurélie , Guedj Fayçal , Po Chrystelle , Smith Desmond J. , Rubin Edward , Rivals Isabelle , Beloeil Jean‐Claude , Gillet Brigitte , Delabar Jean‐Maurice
Published: January 2008

A yeast artificial chromosome (YAC) transgenic murine model of partial trisomy 21 overexpressing five human genes—including DYRK1A, which encodes a serine threonine kinase involved in cell cycle control—has been shown to present an increase in brain weight. We analyzed this new phenotype by measuring total and regional brain volumes at different ages, using a 7 Tesla magnetic resonance imaging volumetric approach. Volumetric measurements showed a total volume increase of 13.6% in adult mice. Changes in brain morphogenesis were already visible at a very early postnatal stage (postnatal days 2–7). Region‐specific changes were characterized from postnatal day 15 to 5 months. These results, made it possible to define region‐specific effects of DYRK1A overexpression, with the strongest increase seen in the thalamus–hypothalamus area (24%). Anat Rec, 291:254–262, 2008. © 2008 Wiley‐Liss, Inc.
Histomorphometric and Densitometric Changes in the Femora of Spinal Cord Transected Mice
Authors: Picard Sylvain , Lapointe Nicolas P. , Brown Jacques P. , Guertin Pierre A.
Published: January 2008

Spinal cord injury (SCI) leads generally to significant bone tissue loss within a few months to a few years post–trauma. Although, increasing data from rat models are available to study the underlying mechanisms of SCI‐associated bone loss, little is known about the extent and rapidity of bone tissue changes in mouse models of SCI. The objectives are to characterize and describe quantitatively femoral bone tissue changes during 1 month in adult paraplegic mice. Histomorphometric and densitometric measurements were performed in 3‐ to 4‐month‐old CD1 mice spinal cord transected at the low‐thoracic level (Th9/10). We found a general decrease in bone volume (−22%), trabecular thickness (−10%), and trabecular number (−14%) within 30 days post‐transection. Dual‐energy X‐ray absorptiometric measurements revealed no change in bone mineral density but a significant reduction (−14%) in bone mineral content. These results show large structural changes occurring within only a few weeks post–spinal cord transection in the femora of adult mice. Given the increasing availability of genetic and molecular research tools for research in mice, this murine model may be useful to study further the cellular and molecular mechanisms of demineralization associated with SCI. Anat Rec, 291:303–307, 2008. © 2008 Wiley‐Liss, Inc.
Ultrastructure of Anterior Uterus of the Oviduct and the Stored Sperm in Female Soft‐Shelled Turtle,Trionyx sinensis
Authors: Han Xiangkun , Zhangli Li , Li Meiying , Bao Huijun , Hei Nainan , Chen Qiusheng
Published: January 2008

Ultrastructure of sperm storage in female soft‐shelled turtle,Trionyx sinensiswas examined under light and electron microscopes. Sperm storage tubules are restricted to the anterior of the uterus. These tubules developed either by folding or fusion of the oviductal mucosal folds and are lined by both ciliated and secretory cells. Ciliated cells are characterized by a few microvilli and prominent cilia in the apical membranes. A prominent feature of the secretory cell is the presence of secretory granules in the supranuclear region. The size, shape, and electron density of these granules vary markedly. The secretory product is released mainly by exocytosis into the oviductal lumen, where it appears as flocculent material. The unique structure in the base of the epithelium, the basal border of the cell—the basal lamina—and a blood vessel layer, is presumed to be a important barrier, by which the nourishment exchange and the microenvironment maintenance are ensured. The gland cell is presented with numerous, round, membrane‐bound secretory granules of moderate to high electron densities. We divide these granules into three types according to their appearance: (1) membrane bounded granules with high‐homogeneous electron density, (2) membrane bounded granules with moderate‐homogeneous electron density, (3) membrane bounded, electron dense granules with concentric structures. These granules are presented as different stages of the secretions in the gland cell. The junction complexes are markedly distributed between cells, which are important in keeping stability and the microenvironment maintenance of the sperm storage tubules. Sperm stored in the tubules are heterogeneous in cytology. In addition to the mature sperm in the lumen, sperm with large chromatic granules are found, which are presumed to be immature sperm and are being in the process of nuclear condensation. Several spermatozoa in the tubules are exhibited with definitive indications of degeneration of the nuclei. The nuclear volume increases. The electron density of the central cores in mitochondria declines, combined with the deterioration of concentric membrane structure. Those changes are possibly due to the long time storage of the sperm in sperm storage tubules, and the leakage of reactive oxygen species is suggested to be a major cause. We conclude that the ultrastructure character of sperm storage in the oviduct ofTrionyx sinensisis unique, in addition to having a basal function in secretion and the cilia swing, the tubules also provide an available microenvironment for the sperm to long time stored. The degenerative sperm in the tubules might be related to paternity‐specific reproductive adaptations, and the sperm competition might occur during long time storage. Anat Rec, 291:335–351, 2008. © 2008 Wiley‐Liss, Inc.
Prenatal growth retardation, microcephaly, and eye coloboma in infant with multiple congenital anomalies: Further delineation of presumed new dysmorphic syndrome
Authors: Cuturilo Goran , Jovanovic Ida , Vukomanovic Goran , Djukic Milan , Stefanovic Igor , Atanskovic‐Markovic Marina
Published: January 2008

BACKGROUND:

Ten years ago an unusual association of prenatal growth retardation, microcephaly, coloboma of the iris/eye anomalies, congenital heart defects, and urogenital anomalies was reported for the first time in three siblings. Autosomal recessive inheritance was presumed. This finding has been included in London Winter‐Baraitser Dysmorphology Database as a separate entity, but still has not been classified as a distinct syndrome.

CASE:

We report an infant with an association of prenatal growth retardation, microcephaly, facial dysmorphism, eye anomalies, congenital heart defects, and testis retention. Mild craniofacial dysmorphism consists of sloped forehead, bulbous nose tip, and micrognathia. Eye anomalies include coloboma of the iris, choroidea, and optic nerve as well as lens dislocation. The patient also presents with ventricular and atrial septal defects, hypoplastic mitral valve, persistent left superior vena cava, accessory spleen, and club foot.

CONCLUSIONS:

To the best of our knowledge, this is the second family and the fourth case with this pattern of birth defects reported worldwide so far. We presume that this combination of multiple congenital anomalies and growth retardation constitutes a newly recognized syndrome of likely autosomal recessive inheritance. So far no data suggest etiological impact of consanguinity, parental age, or environmental factors. Birth Defects Research (Part A) 2008. © 2008 Wiley‐Liss, Inc.
FTIR microspectroscopic analysis of the effects of certain drugs on oxidative stress and brain protein structure
Authors: Carmona P. , Rodríguez‐Casado A. , Alvarez I. , de Miguel E. , Toledano A.
Published: January 2008

This study reports the changes in lipids and proteins of different brain areas of nicotine, D(+)‐amphetamine, and nicotine and D(+)‐amphetamine treated rats by monitoring lipid peroxidation and protein β‐sheet formation using infrared microspectroscopy. Compared with the untreated brain samples, the peroxide level is relatively higher in the amphetamine‐treated brain sections, both in the cortex and hippocampus area. However, this peroxide increase is attenuated when administering amphetamine plus nicotine. Analogous drug‐dependent trends for protein β‐sheet content are observed, which suggests a connection between lipid oxidation involved in oxidative stress and β‐sheet protein structure generally present in neurodegenerative diseases. The above property of nicotine is of interest, in the sense that it might reduce the production of β‐amyloid proteins in Alzheimer's disease. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 548–554, 2008.

This article was originally published online as an accepted preprint. The (Published Online) date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Rescue angioplasty after failed fibrinolysis foracute myocardial infarction: Predictors of a failed procedure and 1‐year mortality
Authors: Kunadian Babu , Vijayalakshmi Kunadian , Dunning Joel , Sutton Andrew GC , Muir Douglas F , Wright Robert A , Hall James A , de Belder Mark A
Published: January 2008

Background:

Rescue angioplasty (rPCI) for failed fibrinolysis is associated with a low mortality if successful, but a high mortality if it fails. The latter may reflect a high‐risk group or harm in some patients. Predictors of success or failure of rPCI may aid selection of patients to be treated.

Methods:

Unselected patients referred for rPCI from March 1994 to March 2005 were studied to determine the predictors of a failed procedure and 1‐year mortality.

Results:

Of 440 patients undergoing emergency coronary angiography for failed fibrinolysis (1‐year mortality 18%), 101 had thrombolysis in myocardial infarction flow grade (TFG) 3 in the infarct‐related vessel. rPCI was attempted in 318 of 339 patients with <TFG 3 flow, but not in 21 patients (angiography‐produced TFG 3 [n = 7] or unsuitable anatomy [n = 14]). Of the rPCI cohort, 77% had a successful procedure (no in‐lab death or emergency coronary artery bypass grafting and TFG 3 in the infarct‐related vessel); rPCI failed in 23%. One‐year mortality rates for successful and failed rPCI were 14 and 43%, respectively. Patients with failed rPCI were older and more likely to be diabetic, have anterior MI, be interhospital transfers, be in cardiogenic shock, and less likely to be a current smoker. Shock was the only independent predictor of failed rPCI. Age group >75 years, shock, and final TFG < 3 were independent predictors of 1‐year mortality.

Conclusions:

Cardiogenic shock is an independent predictor of a failed rPCI. Age group >75 years and shock were the only independent clinical predictors of 1‐year mortality. These clinical variables may help in selecting patients for either a strategy of rescue angioplasty after failed fibrinolysis, or in selecting specific patients who might do better with a policy of primary angioplasty. © 2008 Wiley‐Liss, Inc.
Failed percutaneous coronary intervention: A decade of experience in 21,000 patients
Authors: Mattichak Stephen J. , Dixon Simon R. , Shannon Francis , Boura Judith A. , Safian Robert D.
Published: January 2008

Objectives:

The purpose of this study was to evaluate the incidence, mechanisms, and in‐hospital outcomes after failed percutaneous coronary intervention (PCI).

Background:

The most common causes of PCI failure are severe dissection, no‐reflow, and uncrossable total occlusions.

Methods:

Demographic, clinical, procedural, and quality assurance data were recorded in a prospective database to determine the incidence and outcome of failed PCI. Data were analyzed according to the year of PCI: prestent era (PSE 1993–1995), first generation stent era (FGSE 1996–2000), and contemporary stent era (CSE 2000–2003).

Results:

PCI (20,884) were performed over a 10‐year‐period from 1993 through 2003, including 4,344 (20.8%) in the PSE, 9,114 (43.6%) in the FGSE, and 7,426 (35.6%) in the CSE; 19,171 (91.8%) were successful and 1,704 (8.2%) were failures. Nearly 90% of PCI failures are due to no‐reflow or uncrossable total occlusions. Among PCI failures, 7.5% were treated medically and 0.7% required emergency coronary artery bypass grafting (ECABG). PCI success was independently associated with PCI during CSE (OR 1.86, P < 0.0001). ECABG decreased sixfold from 1.2% in the PSE to 0.2% in the CSE.

Conclusions:

Contemporary PCI patients have better procedural outcomes and fewer in‐hospital adverse events than patient treated before the availability of stents. However, recanalization of total occlusions and avoiding no‐reflow will have the most impact on future PCI success. © 2008 Wiley‐Liss, Inc.