bluuebunny/crossref_metadata_2025 huggingface dataset:
Organic carbon in soils of Germany: Status quo and the need for new data to evaluate potentials and trends of soil carbon sequestration
Authors: Prechtel Annette , von Lützow Margit , Uwe Schneider Bernd , Bens Oliver , Bannick Claus G. , Kögel‐Knabner Ingrid , Hüttl Reinhard F.
Published: September 2009

Uncertainties in estimates of soil carbon (C) stocks and sequestration result from major gaps in knowledge of C storage in soils, land‐use history, the variability of field measurements, and different analytical approaches applied. In addition, there is a lack of long‐term datasets from relevant land‐use systems. As in many European countries, a national database on soil organic carbon (SOC) including all relevant information for the determination of soil C stocks is likewise missing in Germany. In this paper, we summarize and evaluate the present state of knowledge on organic‐C contents/pools in soils of Germany and discuss the need for the acquisition and access to new data on soil organic carbon.

Despite the number of agricultural sites under permanent soil monitoring, regional surveys on SOC, comprehensive ecosystem studies, and long‐term field experiments, there is a striking lack of data in Germany particularly with regard to agricultural soils. Apart from a missing standardization of methods and homogeneous baseline values, the implementation of a periodic, nation‐wide soil inventory on agricultural soils is required in order to simultaneously record information on land use, land‐use change, and agricultural practice. In contrast, the existing national inventory of forest soils provides information on C‐stock changes in forest soils, although there is some concern with regard to the representativeness of the sampling design to adequately address the problem of spatial heterogeneity and temporal variability.

It is concluded that the lack of comprehensiveness, completeness, actuality, data harmonization, and standardized sampling procedures will further prevent the establishment of a SOC database in Germany with regard to the monitoring of trends in soil C pools and fluxes and the assessment of long‐term C‐sequestration potentials of soils under different land use. A future soil inventory should represent the heterogeneity of organic matter through functionally different SOC pools, topsoil characteristics as well as content, pool, and flux data for the deeper mineral‐soil compartments.
Fiber‐optic SERS sensor with optimized geometry: testing and optimization
Authors: Pesapane Andrea , Lucotti Andrea , Zerbi Giuseppe
Published: September 2009

A unique, geometry‐optimized, surface‐enhanced Raman scattering (SERS) fiber‐optic sensor has been recently developed and built. Though this class of sensors can be very useful in many applications, their use is greatly hindered by the fact that their reusability can hardly be achieved because of the irreversible adsorption of the analyte molecules on the SERS‐active substrate. Different substrates have been tested on our sensor with the purpose of increasing its reusability by means of cleaning procedures or good reproducibility in manufacturing the sensor, keeping, however, the same enhancement. We show that a partial reusability of the sensor is possible using SERS‐active substrates prepared by a standard process of immobilization of silver nanoparticles with 3‐aminopropyltrimethoxysilane. We also show that a fairly good reproducibility can be achieved with a low‐cost substrate realized in a short time by depositing a layer of polyvinyl alcohol (PVA) containing silver nanoparticles on the etched fiber tip. We prove as well that measurements are possible even with nanoparticles dispersed in the analyte solution instead of using a substrate directly made on the sensor tip. Finally, we have successfully tested our sensor with some molecules cited in EFSA (European Food Safety Authority) and FDA (Food and Drug Administration) reports as molecules for which new detection methods are necessary. Copyright © 2009 John Wiley & Sons, Ltd.
Capillary electrophoresis with dual laser detection in separation of amplified fragment length polymorphism fragments
Authors: Stefanowicz‐Hajduk Justyna , Filipowicz Natalia , Kosinski Igor , Ochocka J. Renata
Published: September 2009

We are presenting the application of CE technique with dual‐channel LIF detection for the simultaneous separation of DNA fragments labeled with two different fluorescence dyes. The optimal conditions of the analysis were determined for the separation of amplified fragment length polymorphism (AFLP) fragments labeled with 5′‐6‐carboxyfluorescein (6‐FAM) and the DNA size standard labeled with sulfoindocyanine succinimidyl ester (Cy‐5). CE equipped with both argon ion and diode lasers is a good alternative for sequencers and might be applied in analyses of PCR products generated by various fingerprinting methods.
Self‐Assembly of a Modified Amyloid Peptide Fragment: pH‐Responsiveness and Nematic Phase Formation
Authors: Hamley Ian W. , Castelletto Valeria , Moulton Claire , Myatt Daniel , Siligardi Giuliano , Oliveira Cristiano L. P. , Pedersen Jan Skov , Abutbul Inbal , Danino Dganit
Published: September 2009

The self‐assembly of peptide YYKLVFFC based on a fragment of the amyloid beta (Aβ) peptide, Aβ16–20, KLVFF has been studied in aqueous solution. The peptide is designed with multiple functional residues to examine the interplay between aromatic interactions and charge on the self‐assembly, as well as specific transformations such as the pH‐induced phenol–phenolate transition of the tyrosine residue. Circular dichroism (CD) and Fourier‐transform infrared (FTIR) spectroscopies are used to investigate the conditions for β‐sheet self‐assembly and the role of aromatic interactions in the CD spectrum as a function of pH and concentration. The formation of well‐defined fibrils at pH 4.7 is confirmed by cryo‐TEM (transmission electron microscope) and negative stain TEM. The morphology changes at higher pH, and aggregates of short twisted fibrils are observed at pH 11. Polarized optical microscopy shows birefringence at a low concentration (1 wt.‐%) of YYKLVFFC in aqueous solution, and small‐angle X‐ray scattering was used to probe nematic phase formation in more detail. A pH‐induced transition from nematic to isotropic phases is observed on increasing pH that appears to be correlated to a reduction in aggregate anisotropy upon increasing pH.

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Full‐Color Processible Electrochromic Polymers Based on 4,4‐Dioctyl‐Cyclopentadithiophene
Authors: Wu Chun‐Guey , Lu Ming‐I , Tsai Pei‐Fang
Published: September 2009

Three soluble electrochromic copolymers based on 4,4‐di‐octyl‐cyclopentadithiophene (DOCPDT): PDOCPDT‐OT, PDOCPDT‐PT, and PDOCPDT‐Cz were synthesized and the electrochromic properties were investigated. Colorimetric analysis revealed that red‐colored PDOCPDT‐OT, green‐colored PDOCPDT‐PT and their blue mother polymer PDOCTDT are cathodic coloration polymers. PDOCPDT‐Cz is yellow in its neutral state and shows an anodic electrochromism. The structural flexibility, color diversity, processibility and good electrochromic performance make octyl‐cyclopentadithiophene‐containing polymers prominent candidates for electrochromic applications.

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The Preparation of Copolymers Derived from Thiol‐ene/Cationic Systems by Using a Coupling Agent
Authors: Ortiz Ricardo Acosta , Valdez Aida E. Garcia , Duarte M. Lydia Berlanga , Flores Rodolfo Ovando , Soucek Mark D.
Published: September 2009

A bifunctional monomer with methacrylate and epoxycyclohexyl groups linked by a tetramethyldisiloxane moiety was used as a coupling agent for dual photo and thermally polymerizable Thiol‐Ene/cationic systems. The thiol‐ene system included a tetrafunctional thiol, a trifunctional acrylate and a radical photoinitiator while the cationic system comprised a difunctional epoxycyclohexyl monomer and a cationic photoinitiator. It was found that in a first stage the methacrylate group of the coupling agent reacted with the components of the thiol‐ene system rendering a polysulfide with pendant epoxycyclohexyl groups. In a second stage these pendant groups copolymerized with the epoxy monomer by means of a thermal treatment at 120 °C. When the obtained polymers were analyzed by DMA, an increase in the storage modulus was noticed in comparison with the polymers where no coupling agent was added.
Plasma Copolymerization of Ethylene Glycol and Allylamine
Authors: Gomez Lidia M. , Morales Pilar , Cruz Guillermo J. , Olayo Ma. Guadalupe , Palacios Cuauhtemoc , Morales Juan , Olayo Roberto
Published: September 2009

This work presents the plasma copolymerization of Ethylenglycol and Allylamine with the purpose to obtain thin films of biocompatible random polymers with NH and OH chemical groups. The synthesis used electrical glow discharges with mixtures of the monomers at 13.56 MHz, 10−1 mbar and power between 40 and 120 W. The results were thin films of copolymers with NH, CH, OH, and CC groups of the monomers. The main thermal degradation of the plasma copolymers was found between 100 and 500 °C in one step, suggesting that the material behaves as only one chemical species and not as a mixture. The copolymers absorb an average of 6% of water. The contact angles between the polymers and drops of solutions with concentrations of salts similar to those in the human body vary from 20° to 52° increasing with the power of synthesis. The surfaces varied from smooth to rough as the power of synthesis increases. This physical effect appears as the main variable in increasing the contact angles in the plasma copolymers. The electrical conductivity was in the interval of 10−8 and 10−13 S/m and was considerably influenced by the water content in the polymers. All these data suggests that the plasma copolymers are partially hydrophilic and biocompatible.
Surfactant Concentration Effects on the Aqueous Phase Polymerization of Vinyl Acetate
Authors: Martínez‐Gutiérrez Hugo , Ovando‐Medina Víctor M. , Peralta René D.
Published: September 2009

Vinyl acetate (VAc) in concentrations below the water saturation value was polymerized by batch processes at 60 °C using low surfactant concentrations of sodium dodecyl sulfate (SDS) and potassium persulfate (KPS) as initiator. The effects of surfactant concentration on the reaction kinetics, particle formation and molecular weight were studied. It was found that the average particle diameters decrease between 277 and 18.7 nm as the surfactant concentration is increased from 0 to 11 mmol/L, whereas the weight average molecular weight (Mw) decreases also, with values between 8.7 × 105 ≤ Mw ≤ 1 × 105 Da. It was observed that particle size distributions are strongly affected by the addition of small amounts of surfactant. For the low monomer concentrations used in the polymerizations (0.0137 g/cm3 of water), particles were very stable and no coagulation was observed. High reaction rates were found in all polymerizations. When no SDS was added to the system, lower polymerization rates were obtained at the onset of the reaction due to the low rate of particle formation. The behavior of polymerization rate was inversely proportional to the surfactant concentration, which was ascribed to the increase in the average number of radicals per particle.
Synthesis of Random Copolymers Poly (methylmethacrylate‐co‐azo monomer) by ATRP‐AGET
Authors: Nájera M.A. , Elizalde L.E. , Vázquez Y. , Santos G. de los
Published: September 2009

The synthesis of the azo molecule 1‐(2‐(4‐nitrophenyl) diazenyl) naphtalen‐2‐ol which has been functionalized with a methacryloxyl fraction is now reported. This azo monomer was copolymerized with methyl methacrylate (MMA) by ATRP where the active species is prepared “in situ” after the reduction reaction of the metal complex Cu (II) ‐ HMTETA by tin 2‐ethylhexanoate in 2‐butanone as solvent. Experimental conditions for the controlled homopolymerization of MMA were established. By adjusting the amount of reducing agent, a good correlation between theoretical and experimental molecular weight was obtained. Such conditions were also employed for the random copolymerization of MMA with the synthesized azo monomer.
Syndiospecific Styrene Polymerization in Aliphatic Solvents Catalyzed by FluTi(OiPr)3/MAO: Study of Polymerization Conditions
Authors: Lugo Luis E. , Charles Rogelio , Pérez Odilia , Cadenas Gregorio , Revilla Javier
Published: September 2009

Syndiotactic polymerization of styrene in aliphatic solvents (hexane and cyclohexane) and aliphatic solvent/toluene mixtures was evaluated using a previously reported catalytic system formed by FluTi(OiPr)3/MAO in order to evaluate polymerization reaction conditions and their effect on polymer tacticity. Highly syndiotactic polystyrene was produced indistinctly using pure aliphatic solvent or mixtures with toluene. On the other hand, the effect of polymerization conditions such as temperature, catalyst precursor and styrene concentrations, Al/Ti ratio and aliphatic solvent/toluene ratio over catalytic activity were analyzed.
Catalysts for UHMWPE
Authors: Jones R.L. , Armoush M.
Published: September 2009

Polyolefin coordination catalysts useful for producing UHMWPE are surveyed, including classic Ziegler‐Natta (ZN), current commercial generation ZN, metallocene single site, and non‐metallocene. Catalysts were prepared and compared for productivity and selected polymer properties under a variety of conditions. Classic catalysts used were long lived TiCl3 crystalline metal clusters made by reducing TiCl4 by co‐crystallizing with aluminum alkyls. Data presented from the synthesis and polymerization with these catalysts shows temperature and molecular weight response that were expected for these systems. Commercially available titanium on silica/ magnesium chloride was activated with aluminum alkyls and had higher activity than those of the previous generation. Conditions for polymerizing supported metallocenes for producing polymers in the UHMWPE range were described. Long range “non‐metallocenes” of the phenoxy‐imine class were activated with MAO was tested and reported.
Heterogeneous Polymerization of Ethylene and 1‐Hexene with Me3SiCp2ZrH3AlH2/SiO2 Activated with MAO
Authors: González Rebeca , Morales Elsa , García Maricela , Revilla Javier , Charles Rogelio , Collins Scott , Cadenas Gregorio , Lugo Luis , Pérez Odilia
Published: September 2009

The aluminohydride of zirconocene Me3SiCp2ZrH3AlH2 was supported on pre‐treated SiO2, and its catalytic activity for ethylene polymerization and ethylene‐1‐hexene copolymerization was evaluated in order to compare with the corresponding activity of the complex in solution. As expected for systems based on metallocenes, the aluminohydride of zirconocene complex showed higher activity in solution than in suspension, however its thermal and kinetic stability was significantly increased. The effect of the co‐catalyst concentration (MAO) on the activity and the molecular weight of the polymers are also reported in this study, finding that in heterogeneous phase low concentrations of MAO were used to activate the pre‐catalyst. The MW of the polymers and copolymers synthesized with the supported Me3SiCp2ZrH3AlH2/SiO2 could be controlled by adding molecular hydrogen (H2) as chain transfer agent in the polymerization and copolymerization reactions.
Evaluation of the Performance of a Kinetic Model for Free‐Radical Copolymerization of Vinyl/Divinyl Monomers in Supercritical Carbon Dioxide
Authors: Quintero‐Ortega Iraís A. , García‐Moran Pedro R. , Jaramillo‐Soto Gabriel , Vivaldo‐Lima Eduardo , Luna‐Bárcenas Gabriel
Published: September 2009

The performance of a mathematical model for free radical copolymerization kinetics with crosslinking of vinyl/divinyl monomers in supercritical carbon dioxide previously developed in our group is evaluated using experimental data of conversion versus time and gel fraction versus conversion for copolymerization of styrene and divinylbenzene. The effects of process conditions, type of stabilizer and initial divinyl monomer composition were also assessed. Reasonable agreement between model predictions and experimental data was obtained.
Progress in Controlled Grafting‐From by Nitroxide Chemistry
Authors: Saldívar‐Guerra Enrique , Bonilla‐Cruz José , Hernández‐Mireles Brenda , Ramírez‐Manzanares Grisel
Published: September 2009

A number of substrates (polymers and silica) have been functionalized with nitroxide moieties in order to obtain alkoxyamine groups along the substrate. The functionalized substrates have been further heated in the presence of monomers in order to grow controlled grafts by the grafting – from technique. Tested substrates include polybutadiene (PB), polyisoprene (PI), styrene – isoprene (SIS) and styrene – butadiene (SBS) tri‐block copolymers, EPDM, poly (dimethyl‐siloxane) (PDMS), poly(ethylene glycol) and silica. Two chemical paths involving nitroxide chemistry have been used for the functionalization step and are discussed in this work. In the first path, the substrate is heated in the presence of a nitroxide radical (N) and a radical initiator (I) or using only nitroxide. In the second path, useful for substrates containing hydroxyl groups, the functionalization of the substrate is obtained using an N‐oxoammonium TEMPO bromide salt in the presence of triethyl amine, which forms a peroxide group linked on one end to the substrate and on the other end to the TEMPO moiety. The mechanisms, structures and the resulting polymers (functionalized and grafted) have been studied by GPC, spectroscopic techniques and transmission electron microscopy.
Silicon‐Based and Fluorinated Polymeric Surfactants for Nitroxide Mediated Dispersion Polymerization in Supercritical Carbon Dioxide
Authors: Ramírez‐Wong Diana Guadalupe , Posada‐Vélez Carlos Andrés , Saldívar‐Guerra Enrique , Luna‐Bárcenas J. Gabriel , Ott Christina , Schubert Ulrich S.
Published: September 2009

Block copolymers based on siloxanes and fluorinated block copolymers were synthesized and tested as surfactants for nitroxide mediated polymerizations (NMP) in supercritical carbon dioxide. Styrene was polymerized in the presence of TEMPO at 130 °C using various surfactants. Siloxane‐based surfactants were synthesized by a new route based on NMP; the perfluorinated surfactants were also synthesized by NMP. The dispersion polymerizations of styrene in scCO2 reveal conversions of up to 35% in 4 hours at 19.1 MPa. The resulting polydispersity indices lie in the range 1.2–1.4. The best results are obtained using a perfluorinated surfactant. Preliminary copolymerization experiments of the polystyrene macroinitiator in scCO2 have shown successful chain‐extension with butyl acrylate (BuA) resulting in the formation of a poly (St‐b‐BuA) block copolymer.
Temperature‐Sensitive Hydrogels: A Gentle Way of Concentrating Cellulase Enzymes
Authors: Hernandez Elena , Orozco‐Avila Ignacio
Published: September 2009

The swelling behaviour of a poly(N‐isopropylacrylamide) temperature sensitive hydrogel in fermentation broth was determined as a function of the temperature and compared with that in water. The feasibility of the gel as a device for concentration of cellulase enzymes, produced by the fermentation of the fungus Trichoderma reesei RUT C‐30, was also studied. For the same particle size, gels with different composition showed differences in the swelling time and in the extent of swelling. The time required for collapsing was independent of both the monomer concentration and the degree of crosslinking. During swelling, the gels absorb water and low molecular weight solutes (<100 g/mol), excluding macromolecules such as proteins (>10 kD). The enzymes were concentrated in the solution non‐ absorbed by the gels. Mass balances for fermented broth, total soluble protein and enzyme activity showed a good recovery.
Using Chitosan as a Nucleation Agent in Thermoplastic Foams for Heavy Metal Adsorption
Authors: Vázquez Milton O. , Ramírez‐Arreola Daniel E. , Bernache Javier , Gómez Cesar , Robledo‐Ortiz Jorge R. , Rodrigue Denis , González‐Núñez Rubén
Published: September 2009

Thermoplastics/chitosan‐powder composite foams were prepared by extrusion using azodicarbonamide (ACA) as chemical blowing agent. The effect of chitosan content on morphology (cell size, nucleation density and foam density) of the foams was studied. Chitosan particles are located on the bubbles periphery. Morphological quantification showed that foam cell size decreased and cell population increased with addition of chitosan into polymeric matrix from 1 to 10%. Further, optimum chitosan content was obtained for each polymer. Polymers foamed with chitosan were tested as a chelating resin to adsorb chromium (Cr VI) from different concentration solutions.
Acrylic Bone Cements Modified With Bioactive Filler
Authors: Jasso‐Gastinel Carlos Federico , Enriquez Salvador García , Flores Jorge , Reyes‐González Ignacio , Mijares Eduardo Mendizábal
Published: September 2009

Bioactive cuttlebone Sepia officinalis particles that contain collagen were used to fill poly (methyl methacrylate‐co‐styrene) bone cements, varying size and concentration of filler particles. Cuttlebone was characterized by X‐ray diffraction and plasma atomic emission spectrophotometer. Maximum reaction temperature and cement setting time were determined for composites and reference (copolymer without filler), along with NMR determination of residual monomer concentration. Mechanical properties characterization included stress‐strain, bending, compression, fracture toughness and storage modulus tests. Mechanical results for composites filled with 10 and 30% weight of cuttlebone, complied with norm requirements which opens the possibility for using cuttlebone particles as bioactive filler.
In Situ Production of Polymer‐Capped Silver Nanoparticles for Optical Biosensing
Authors: Giorgetti E. , Giusti A. , Arias E. , Moggio I. , Ledezma A. , Romero J. , Saba M. , Quochi F. , Marceddu M. , Gocalinska A. , Mura A. , Bongiovanni G.
Published: September 2009

Summary: We report on the preparation and spectroscopic characterization of a novel nanocomposite consisting of silver nanoparticles and a fluorescent polymer obtained by in situ ps laser ablation of a silver target. While the polymer is able to detect the fungus Paecilomyces variotii by fluorescence quenching, the composite with silver nanoparticles permits an interaction with both cell walls of spores and mycelia without any appreciable reduction of the overall fluorescence quantum yield.
Mammalian Cell Culture on a Novel Chitosan‐Based Biomaterial Crosslinked with Gluteraldehyde
Authors: Fabela‐Sánchez O. , Zarate‐Triviño D. G. , Elizalde‐Peña E. A. , García‐Carvajal Z. , Sánchez I. C. , Parra‐Cid C. , Gómez‐García R. , Ibarra C. , García‐Gaitán B. , Zavala R. , Guevara‐Olvera L. , Villaseñor‐Ortega F. , Muñoz‐Sanchez C. I. , Perez‐Perez C. , Herrera‐Perez S. , Velasquillo C. , Luna‐Barcenas G.
Published: September 2009

A novel (Chitosan‐g‐Glycidyl Methacrylate)‐Xanthan, (CTS‐g‐GMA)‐X, hydrogel was successfully synthesized at Cinvestav Queretaro. In the present work, we attempt to study the in vitro biocompatibility of (CTS‐g‐GMA)‐X hydrogels as scaffolds for neural cells obtained from cerebral cortex of mice; skin cells from skin of mice; and chondrocytes from human cartilage. The results obtained in the live/dead assay show that the materials maintain the morphology and viability of the cells. However the high friability of the materials prevented an extended test time in this assay. Therefore, glutaraldehyde (GL) was added to the structure as crosslinking agent to enhance friability. All results point out that [(CTS‐g‐GMA)‐X]‐GL hydrogel is viable as a scaffold for chondrocytes and skin cells; and (CTS‐g‐GMA)‐X for neural cell due to their physicochemical properties and biocompatibility with the cells for both materials.
Dynamic Mechanical and Dielectric Relaxation Behavior of Chitosan Films: Influence of Water Content
Authors: González‐Campos J. Betzabe , Prokhorov Evgen , Luna‐Bárcenas Gabriel , Sanchez Isaac C. , Kovalenko Yuriy
Published: September 2009

The dynamic mechanical dielectric behavior of neutralized chitosan films has been investigated as a function of water content and temperature. Chitosan films exhibit three relaxation processes in the low frequency range: the first one between 86–102 °C, it corresponds to the α‐relaxation process and shifts to higher temperatures with decreasing water content; a second relaxation was observed from 80 °C to the onset of thermal degradation (240 °C) and it is identified as the σ‐relaxation often associated with proton mobility; and a third relaxation process in the 240–300 °C temperature range that corresponds to chitosan thermal degradation.
Ionic Conductivity of Polymer Electrolytes
Authors: Cardoso Judith , Vázquez Gerardo , Soria‐Arteche Olivia , Cruz Raúl , González Ignacio
Published: September 2009

In this work, the effect of different salts: LiCF3SO3 (lithium triflate, LiOTf) and LiCl in 1:1 mole ratio in a methacrylate‐type polymer with zwitterionic pendant groups (PMBS‐4) used as host polymer, are evaluated. By means of X‐ray diffraction patterns, the formation of a homogeneous solution is observed in the case of PMBS‐4/LiCl and PMBS‐4/LiOTf. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) allows determination of glass transition temperatures (Tg) and thermal stability of the polymers. Tg values of the two polymer electrolytes are 293 ± 2 K against PMBS‐4 which is 291 K. The initial decomposition temperatures (IDT) for PMBS‐4 and PMBS‐4/Lithium salt are 483 K and 460 K, respectively. The ac ionic conductivity (σ) was obtained using the electrochemical impedance spectroscopy (EIS). It was found that σ increases as temperature rises following a simple Arrhenius behavior and reaches a value of ∼6 × 10−4 S/cm in the case of PMBS‐4/LiCl and ∼2 × 10−2 S/cm in the case of PMBS‐4/LiOTf, both measured at 343 K.
Effect of Di(2‐ethyl hexyl phthalate)/Epoxidized Soybean Oil and Calcium Stearate/Zinc Stearate Ratios on the Tensile Properties of Plasticized PVC Formulations. A Study for Calcium Stearate Rich Formulations
Authors: González‐Ortiz Luis J. , Arellano Martín , Sánchez‐Peña M. Judith
Published: September 2009

Two series of plasticized PVC formulations were prepared, containing one of the following di (2‐ethyl hexyl phthalate)/epoxidized soybean oil ratios (phr/phr): (a) 35/3, (b) 55/3, (c) 45/0 or, (d) 45/6. For each ratio, the following calcium stearate/zinc stearate ratios (phr/phr) were considered: (a) 0.6/0.4, (b) 0.8/0.2 or, (c) 1.0/0.0; all formulations were prepared with a total content of stearate(s) of 1.0 phr. The difference between the series was the preheating of stearates (150 °C, 90 min), carried out before the dry‐blend preparation. The changes of tensile properties produced by the degradation process were measured in ribbons obtained by extrusion.
Tensile Properties of Self‐Crosslinkable Poly(n‐butyl methacrylate‐co‐N‐methylolacrylamide) Films Prepared by Emulsion and Microemulsion Latexes
Authors: Aguilar Jacobo , Rabelero Martín , Mendizábal Eduardo , Nuño‐Donlucas Sergio M. , Arellano Martín , Puig Jorge E.
Published: September 2009

The gel content, swelling degree and mechanical properties of self‐crosslinkable poly(n‐butyl methacrylate‐co‐N‐methylolacrylamide) films made by two‐stage emulsion (using sodium dodecyl sulfate as surfactant) or microemulsion (using cetyltrimethylammonium bromide as surfactant) polymerization processes in the presence of variable amounts of the chain transfer agent, n‐butyl mercaptan, are reported here. Latexes made by microemulsion polymerization contain much smaller nanoparticles with lower amount of gel than those obtained by the emulsion process. Stress‐strain tests in uncured and cured films indicate that microemulsion‐made films are tougher and exhibit smaller deformations at break.
Phase Behavior and Particle Formation of Poly (1H,1H‐dihydrofluorooctyl Methacrylate) in Supercritical CO2
Authors: Santoyo‐Arreola José G. , Vásquez‐Medrano Rubén C. , Ruiz‐Treviño Alberto , Luna‐Bárcenas Gabriel , Sanchez Isaac C. , Ortiz‐Estrada Ciro H.
Published: September 2009

The poly(1H,1H‐dihydrofluorooctyl methacrylate) behavior in supercritical CO2 was determined in relation to the emulsions formation phenomena in surfactants including a CO2‐philic chain and the particles formation process by RESS. The stability conditions show an obvious influence of both the polymer molecular weight and the CO2 density, which are in competence with the thermal effect. The results are consistent with a LCST behavior in function of the molecular weight reaching the θ condition that converges for both the upper critical solution (UCSD) and the critical flocculation density (CFD) for a colloidal system. By using Sanchez‐Lacombe equation of state, a solubility parameter is estimated and it confirms the affinity of the fluorinated polymer with CO2, this in agreement with the literature information that relates surface tension with cohesion energy. In the particles formation by RESS, it was determined that concentration, saturation degree and nozzle diameter have a direct influence on the particle morphology and size; meanwhile, temperature and pre‐expansion pressure are variables used to tune of saturation degree dependent phase behavior. Results show that particles of 200–400 nm can be obtained when 1%wt polymer, homogeneous solution and 130 µm nozzle diameter are used. Under those conditions, the nucleation process and the particles growth and size during precipitation can be controlled; the mechanism is analyzed in relation to the phase behavior.
Polymer Chain Collapse in Supercritical Fluids. 2. Experimental Evidence
Authors: Ortiz‐Estrada C. H. , Luna‐Bárcenas G. , Alvarado J. F. J. , González‐Alatorre G. , Sanchez I. C. , Ramírez N. Flores , García Salomón R. Vásquez , Castillo‐Tejas J. , Manero‐Brito O.
Published: September 2009

The phase behavior of a polymer in a supercritical solvent at the LCST equilibrium limits is described in this work, in the proximity of θ point, proposing the use of a conformational parameter, Ψ. The results obtained by molecular simulation in an NVT ensemble have been correlated by extensive, varied experimental information. The relationship between polymer/solvent solubility parameters has shown that the behavior of these systems is a function of the energetic structure‐interaction relationship between the polymer chain and the solvent. Ψ results in a generalized parameter indicative of the phase stability of the solution. At greater magnitudes, the solution becomes unstable, requiring elevated pressure to stabilize. However, stable solutions are found at lower pressures when Ψ approaches 1. The experimental evidence, together with the determination of the solubility parameter with the Sanchez‐Lacombe equation (also obtained from the literature) strengthens this observation. The analysis of the polar contribution on the Hansen Parameter (HSP) enables their effect to be studied in systems where high polar interactions between the polymer and solvent (as in the case of biopolymers) are expected.
Water‐Based Coatings Based on Mixtures of Acrylic Dispersions and Alkyd Emulsions
Authors: Kivit Patrick J. J. , Aramendia Esteban , Cabrera Amadeo A. , Ríos Lucero M.
Published: September 2009

In this work acrylic dispersions were mixed with alkyd emulsions to obtain coatings that lower the amount of volatile organic compounds (VOC) in surface coatings. The advantage of this approach is that the fast drying of the acrylic is combined with the good film properties of the alkyd. Films produced with an alkyd and a soft acrylic (AA1) did not exhibit good film properties. Whereas, films produced with a hard acrylic (SA1 and AA2) and a soft alkyd gave films with good appearance, appropriate drying times, superior pendulum hardness and promising values of gloss. VOC was calculated below 25 g/L. The novel mixtures may be applied as high gloss enamels for architectural coatings.
Polymeric Surfaces with Anticoagulant, Antifouling, and Antimicrobial Attributes
Authors: Yu Min , Urban Marek W.
Published: September 2009

Summary: Recent advances in developments of anticoagulant, antifouling, and antimicrobial polymeric surfaces with the focus on surface modifications of polymeric materials as well as the influence of nanosize materials on interactions with biological systems are discussed. Controllable surface modifications using microwave plasma reactions in the presence of maleic anhydride provides a platform for attaching acid groups to inert polymeric surfaces which serves as a reactive anchor for further reactions. To effectively attach bioactive species inhibiting interactions with biological systems it is often necessary to attach a molecular spacer that facilitates mobility to terminal bioactive species.
Structural and Electrical Characterization of Isotactic PMMA Thin Films Deposited by Spin Coating
Authors: García B. , Ocampo M.A. , Luna‐Bárcenas G. , García R. , Mejia I. , Melgarejo F. Rodríguez , Loyola C. H. OR. Fernández , Catalán K. Sánchez , Ramírez N. Flores , García Salomón R. Vásquez , Ortiz‐Estrada C. , Garcia‐Gaitan B. , Zavala R.
Published: September 2009

Thin PMMA films have been studied extensively for their potential applications as membranes, microlithography and optical applications. PMMA has been recently use like gate dielectric film in OTFT. In this paper we present the structural and electrical characteristics of isotactic PMMA (i‐PMMA) thin films prepared by spin coating depositions. The electrical characterization was done using a simple capacitive structure to observe current density across dielectric film and voltage breakdown. The i‐PMMA films possess low current density across dielectric (1 × 10−8 A/cm2) and the breakdown voltage is higher than 100 V.
Strain Effect on the Electrical Conductivity of CB/SEBS and GP/SEBS Composites
Authors: Estrada Moreno Iván Alziri , Díaz Diaz Alberto , Mendoza Duarte Mónica Elvira , Ibarra Gómez Rigoberto
Published: September 2009

Carbon black (CB) and Graphite (GP) were embedded in poly(styrene–ethylene/butylene–styrene) (SEBS) to form CB/SEBS and GP/SEBS composites. The electrical resistance was monitored in situ during tensile, compressive and dynamic mechanical tests, obtaining a correlation between the electrical response and strain. In the dynamic test the conductivity of the composites showed almost the same behavior than the elastic modulus, decreasing at deformations higher than 1%.
Neuropsychiatric symptoms in Parkinson's disease
Authors: Aarsland Dag , Marsh Laura , Schrag Anette
Published: September 2009

Neuropsychiatric symptoms are common in Parkinson's disease, even at the earliest stages, and have important consequences for quality of life and daily functioning, are associated with increased carer burden and increased risk for nursing home admission. In addition to cognitive impairment, a wide range of neuropsychiatric symptoms have been reported. In this article, the epidemiology, clinical course, diagnosis, and management of some of the most common neuropsychiatric symptoms in PD are discussed: depression, anxiety, apathy, fatigue, and psychotic symptoms. Although much is known regarding the prevalence and course of these symptoms, the empirical evidence for how to manage these symptoms is limited at best. There is thus an urgent need for systematic studies for the pharmacological and non‐pharmacological management of these symptoms. © 2009 Movement Disorder Society
Parkinson's disease tremor is diminished with relaxation guided imagery
Authors: Schlesinger Ilana , Benyakov Orna , Erikh Ilana , Suraiya Suheir , Schiller Yitzhak
Published: September 2009

Patients with Parkinson's disease (PD) may have pronounced tremor that exacerbates during stress. To determine whether PD tremor improves with relaxation guided imagery (RGI) and relaxing music. Twenty patients with PD with moderate to severe tremor participated in sessions where relaxation techniques were implemented. Tremor was objectively monitored using an accelerometer. RGI dramatically decreased tremor in all 20 patients (baseline 270.38 ± 85.82 vs. RGI 35.57 ± 43.90 movements per minute P < 0.0001). In 15 patients, RGI completely abolished tremor for 1–13 min. Average tremor activity remained significantly bellow baseline both 15 min and 30 min after RGI was discontinued (P < 0.001). Patients reported improvement lasting 2–14 hours (mean 6.8 ± 3.8). Relaxing music significantly reduced tremor but to a lesser degree than RGI (220.04 ± 106.53 movements per minute P = 0.01). Self‐relaxation had no significant effect on tremor. RGI can supplement conventional medical treatments for tremor in patients with PD on best medical treatment. © 2009 Movement Disorder Society
A novel method for systematic analysis of rigidity in Parkinson's disease
Authors: Endo Takayuki , Okuno Ryuhei , Yokoe Masaru , Akazawa Kenzo , Sakoda Saburo
Published: September 2009

We propose a novel system that analyzes the components of rigidity in Parkinson's disease (PD) usually perceived by physicians, in a very simple and systematic way for routine clinical practice. Our system is composed of two compact force sensors, a gyroscope, and EMG surface electrodes. Muscle tone was assessed in 24 healthy elderly subjects and 27 PD patients by passive extension and flexion of the elbow joint with ramp‐and‐hold trajectory. Torque and angle data in the dynamic phase were used to calculate “elastic coefficients” in extension and flexion, and the mean value of torque in each dynamic phase at each joint angle (defined as “Bias”) was also calculated. The muscle activity index in the static phase (EMG Index) was obtained for both biceps brachii (BB) and triceps brachii (TB) muscles. “Elastic coefficients,” sum of the “difference of Bias” and “EMG Index” for BB all correlated well with UPDRS score. Based on our results, Parkinsonian rigidity consists of both an “elastic” component and a “difference of Bias” component, and neurologists may assess greater rigidity when either one or both components are high in value. The EMG index was useful for differentiating PD patients with slight rigidity from healthy elderly adults. © 2009 Movement Disorder Society
Brain atrophy and white matter hyperintensities in early Parkinson's disease
Authors: Dalaker Turi O. , Larsen Jan P. , Bergsland Niels , Beyer Mona K. , Alves Guido , Dwyer Michael G. , Tysnes Ole‐Bjorn , Benedict Ralph H.B. , Kelemen Arpad , Bronnick Kolbjorn , Zivadinov Robert
Published: September 2009

The purpose of this research was to examine the extent of global brain atrophy and white matter hyperintensities (WMH) in early Parkinson's disease (PD) compared to normal controls (NC), to explore the relationship between the MRI variables and cognition in PD. In this multicenter study we included 155 PD patients (age 65.6 ± 9.1 years, disease duration 26.7 ± 19.9 months) and 101 age‐matched NC. On 3D‐T1‐WI, we calculated normalized brain volumes using SIENAX software. WMH volumes were assessed semiautomatically. In PD patients, correlation and regression analyses investigated the association between atrophy and WMH outcomes and global, attention‐executive, visuospatial, and memory cognitive functions. Regression analysis was controlled for age, education, depression score, motor severity, cerebrovascular risk, and sex. No significant MRI variable volume group differences were found. The models did not retain any of the imaging variables as significant predictors of cognitive impairment. There was no evidence of brain atrophy or higher WMH volume in PD compared to NC, and MRI volumetric measurements were not significant predictors of cognitive functions in PD patients. We conclude that global structural brain changes are not a major feature in patients with incident PD. © 2009 Movement Disorder Society
Loss of nocturnal blood pressure fall in various extrapyramidal syndromes
Authors: Schmidt Claudia , Berg Daniela , Herting  , Prieur Silke , Junghanns Susann , Schweitzer Katherine , Globas Christoph , Schöls Ludger , Reichmann Heinz , Ziemssen Tjalf
Published: September 2009

Cardiovascular autonomic dysfunction has frequently been reported in some patients with extrapyramidal syndromes, especially multiple system atrophy (MSA) but also Parkinson's disease (PD). However, there are only few reports on the prevalence of cardiovascular autonomic dysfunction progressive in supranuclear palsy (PSP). Moreover, the relation of detailed cardiovascular testing and easy to assess 24‐hour ambulatory blood pressure (BP) is not known. Our study evaluates 24‐hour ambulatory BP monitoring in patients with PD, PSP, MSA, and corresponding controls (Con) and relates the findings to the results of comprehensive cardiovascular autonomic testing. Twenty‐three patients with PD, 25 patients with PSP, 25 patients with MSA, and 26 corresponding controls were studied by 24‐hour ambulatory BP monitoring (ABPM) in comparison to cardiovascular autonomic testing. Patients with PD, PSP, and MSA presented frequently with a pathological nocturnal BP regulation (no decrease or even an increase of nocturnal BP) in comparison to the control group (PD 48%, PSP 40%, MSA 68% vs. Con 8%). In MSA and PD patients, the frequent pathological BP increase during night was closely correlated to orthostatic hypotension. Since loss of nocturnal BP fall is frequent in patients with extrapyramidal syndromes, even if they are free of subjective autonomic dysfunction, we recommend 24‐hour ABPM as an easy to perform screening test, especially if detailed autonomic testing is not available. Pathological loss of nocturnal BP fall may account for increased cardiovascular mortality in extrapyramidal syndromes. © 2009 Movement Disorder Society
NMR‐based metabonomics analysis of mouse urine and fecal extracts following oral treatment with the broad‐spectrum antibiotic enrofloxacin (Baytril)
Authors: Romick‐Rosendale Lindsey E. , Goodpaster Aaron M. , Hanwright Philip J. , Patel Neil B. , Wheeler Esther T. , Chona Deepika L. , Kennedy Michael A.
Published: September 2009

The human gastrointestinal tract is home to hundreds of species of bacteria and the balance between beneficial and pathogenic bacteria plays a critical role in human health and disease. The human infant, however, is born with a sterile gut and the complex gastrointestinal host/bacterial ecosystem is only established after birth by rapid bacterial colonization. Composition of newborn gut flora depends on several factors including type of birth (Ceasarian or natural), manner of early feeding (breast milk or formula), and exposure to local, physical environment. Imbalance in normal, healthy gut flora contributes to several adult human diseases including inflammatory bowel (ulcerative colitis and Crohn's disease) and Clostridium difficile associated disease, and early childhood diseases such as necrotizing enterocolitis. As a first step towards characterization of the role of gut bacteria in human health and disease, we conducted an 850 MHz 1H nuclear magnetic resonance spectroscopy study to monitor changes in metabolic profiles of urine and fecal extracts of 15 mice following gut sterilization by the broad‐spectrum antibiotic enrofloxacin (also known as Baytril). Ten metabolites changed in urine following enrofloxacin treatment including decreased acetate due to loss of microbial catabolism of sugars and polysaccharides, decreased trimethylamine‐N‐oxide due to loss of microbial catabolism of choline, and increased creatine and creatinine due to loss of microbial enzyme degradation. Eight metabolites changed in fecal extracts of mice treated with enrofloxacin including depletion of amino acids produced by microbial proteases, reduction in metabolites generated by lactate‐utilizing bacteria, and increased urea caused by loss of microbial ureases. Copyright © 2009 John Wiley & Sons, Ltd.
Micromelosides A–D, four new coumarins from the stem bark of Micromelum falcatum
Authors: Luo Xiongming , Qi Shuhua , Yin Hao , Xiao Zhihui , Zhang Si
Published: September 2009

Four new coumarins, micromelosides A–D, together with four known coumarins were isolated from the stem bark of Micromelum falcatum. The complete assignments of the 1H and 13C NMR chemical shifts for these new compounds were achieved by means of 1D and 2D NMR techniques, including 1H‐1H COSY, HSQC, HMBC and NOE difference. Copyright © 2009 John Wiley & Sons, Ltd.
Electrical impedance myography: Background, current state, and future directions
Authors: Rutkove Seward B.
Published: September 2009

Electrical impedance myography (EIM) is a non‐invasive technique for the evaluation of neuromuscular disease that relies upon the application and measurement of high‐frequency, low‐intensity electrical current. EIM assesses disease‐induced changes to the normal composition and architecture of muscle, including myocyte atrophy and loss, edema, reinnervation, and deposition of endomysial connective tissue and fat. With application of single‐frequency electrical current, EIM can be used to help grade the severity of neuromuscular disease. Assessing electrical impedance across a spectrum of applied frequencies and with current flow at multiple orientations relative to major muscle fiber direction can provide a more complete picture of the condition of muscle. EIM holds the promise of serving as an indicator of disease status. It may be useful in clinical trials and in monitoring effectiveness of treatment in individual patients; ultimately, it may also find diagnostic application. Ongoing efforts have been focused on obtaining a deeper understanding of the basic mechanisms of impedance change, studying EIM in a variety of clinical contexts, and further refining the methods of EIM data acquisition and analysis. Muscle Nerve, 2009
Evolution of the phenotype in a family with an LMNA gene mutation presenting with isolated cardiac involvement
Authors: Carboni Nicola , Porcu Maurizio , Mura Marco , Cocco Eleonora , Marrosu Giovanni , Maioli Maria A. , Solla Elisabetta , Tranquilli Stefania , Orrù Pierpaolo , Marrosu Maria G.
Published: September 2009

The aim of this study is to report the evolution of a phenotype in members of a single family carrying the heterozygous exon 1 c.178 C/G, p.Arg 60 Gly LMNA gene mutation. All mutated family members underwent neurological and cardiological assessments for a period ranging from 10 to 20 years. At onset, 4 affected adult members presented a phenotype that required pacemaker implantation. Three subjects underwent cardiac transplantation leading to long‐term survival in 2 of them. One of the 3 longest surviving relatives manifested late lipodystrophy, and the other 2 had lipodystrophy, insulin‐resistant diabetes, and distal peripheral neuropathy. The findings demonstrate that the exon 1 c.178 C/G, p.Arg 60 Gly LMNA gene mutation is associated with a novel phenotype featuring cardiac involvement followed by late lipodystrophy, diabetes, and peripheral axonal neuropathy. Muscle Nerve, 2010
Voluntary activation in the triceps brachii at short and long muscle lengths
Authors: Cheng Arthur J. , Rice Charles L.
Published: September 2009

The aim was of this study was to determine whether voluntary activation calculated using the interpolated twitch technique (ITT) would be underestimated by muscle length–induced changes in the twitch amplitude evoked at rest after maximum voluntary contraction (MVC) in the elbow extensors. In 12 healthy men, calculated voluntary activations were compared at short (20° of elbow flexion) and long muscle lengths (120°) using the actual post‐MVC doublet, and the predicted post‐MVC doublet estimated from linear or nonlinear extrapolations. Actual post‐MVC doublet amplitudes were smaller at 20° versus 120°. At 20°, the predicted post‐MVC doublet obtained from nonlinear extrapolation was larger, and voluntary activation values improved by 5–33% at the submaximal voluntary contraction intensities (≤80% of MVC). When voluntary drive is compromised, this method of extrapolation is useful to account for mechanical limitations that blunt the actual post‐MVC doublet, which otherwise leads to underestimation of voluntary activation. Muscle Nerve, 2010