bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential effects of the aromas of Salvia species on memory and mood
Authors: Moss Lucy , Rouse Michelle , Wesnes Keith A. , Moss Mark 
Published: June 2010

AbstractThis study investigated the potential for the aromas of the essential oils of Salvia species to affect cognition and mood in healthy adults. Research has demonstrated that orally administered Salvia officinalis and Salvia lavandulaefolia are capable of modulating cognition and mood. The active compounds in the herbal products might also be present in the aromas and so produce similar effects. In an independent groups design, three conditions, S. officinalis aroma, S. lavandulaefolia aroma and no aroma were employed. One hundred and thirty‐five healthy volunteers acted as participants, with 45 in each condition. Cognitive performance was assessed via the Cognitive Drug Research (CDR) System. Bond–Lader mood scales measured the participants’ mood on three dimensions before and after the cognitive tasks. Data analysis revealed that the S. officinalis aroma group performed significantly better than the control group on the quality of memory and secondary memory primary outcome factors from the test battery. The Alert mood measure displayed significant differences between both aromas and the control condition. These findings suggest that the aromas of essential oils of Salvia species reproduce some but not all of the effects found following oral herb administration, and that interesting dissociations occur between subjective and objective responses. Copyright © 2010 John Wiley & Sons, Ltd.
SEDVIEW, Real‐time Sedimentation Analysis
Authors: Hayes David B. , Stafford Walter F. 
Published: June 2010

AbstractThe ability to obtain a sedimentation coefficient distribution as the run proceeds, and to get an early idea of the quality of a particular sample, has not been made available in real‐time during the run in any of the existing software packages. It is desirable on many occasions to be able to see the number of components present in a sample at an early stage of the run. The ability to ascertain the extent of heterogeneity of sample would help enormously to reduce the amount of time that is necessary to obtain that information. Most software packages currently available require that the run be completed before analysis is carried out or at least some of the early scans analyzed off‐line to determine if the run should continue. A software package called SEDVIEW has been developed by us to allow early analysis in real‐time.magnified image
Effect of the Deformation Temperature on the Shape‐Memory Behavior of Epoxy Networks
Authors: Feldkamp Diane M. , Rousseau Ingrid A. 
Published: June 2010

AbstractThe impact of the deformation conditions, specifically the temperature, on the shape‐memory behavior and characteristics of epoxy SMPs is studied. By simply varying the temperature during deformation (i.e., the programming step of the SM effect), the ultimate strain of the formulated epoxy was improved three‐ to five‐fold, thereby providing for an increased range of reachable deformation strains during SM thermo‐mechanical cycling. This research unveils newly developed epoxy‐based SMPs with improved deformability range and high strength with intrinsically good thermal and chemical stability.magnified image
Water purification by membranes: The role of polymer science
Authors: Geise Geoffrey M. , Lee Hae‐Seung , Miller Daniel J. , Freeman Benny D. , McGrath James E. , Paul Donald R. 
Published: June 2010

AbstractTwo of the greatest challenges facing the 21st century involve providing sustainable supplies of clean water and energy, two highly interrelated resources, at affordable costs. Membrane technology is expected to continue to dominate the water purification technologies owing to its energy efficiency. However, there is a need for improved membranes that have higher flux, are more selective, are less prone to various types of fouling, and are more resistant to the chemical environment, especially chlorine, of these processes. This article summarizes the nature of the global water problem and reviews the state of the art of membrane technology. Existing deficiencies of current membranes and the opportunities to resolve them with innovative polymer chemistry and physics are identified. Extensive background is provided to help the reader understand the fundamental issues involved. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010
Aggregation, gelation instability, and morphologies of diblock copolymers consisting of poly(p‐benzamide) and poly(m‐benzamide)
Authors: Kataoka Toshiyuki , Ohishi Tomoyuki , Yokozawa Tsutomu , Ikehara Takayuki 
Published: June 2010

AbstractThe solution, gelation, and morphological properties of monodisperse aromatic polyamide diblock copolymers consisting of poly(p‐benzamide) (PpBA), poly(m‐benzamide) (PmBA), and poly(N‐octyl m‐benzamide) (POmBA) were investigated. The block copolymers of these polymers, PpBA‐block‐POmBA and PmBA‐block‐POmBA, formed spherical micelles or amorphous aggregates in many solvents in addition to physical gels at concentrations higher than 5 wt %. A temperature‐induced sol‐gel transition was also exhibited for PpBA‐block‐POmBA in solvents with high boiling points such as N,N‐dimethylacetamide and N‐methylpyrrolidone (NMP), although the transition was not entirely thermoreversible; the transition temperature decreased by annealing at ∼80 °C. Dynamic light scattering measurements of the PpBA‐block‐POmBA/NMP solutions revealed that metastable micelles in the sol state reorganized into smaller micelles upon annealing at 90 °C. The block copolymer, which forms strong associations, exhibited some transient structure as indicated by the need to sufficiently anneal the solution to reach equilibrium. Network‐like patterns with characteristic length of ∼10 μm appeared on the gel surfaces upon evaporation of volatile solvents such as dichloromethane and chloroform, in which the copolymers were observed to aggregate. The unique properties of the copolymers originate from interactions between the highly polar NH aromatic polyamide blocks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1732–1739, 2010
Characterization and electrical transport properties of polyaniline and multiwall carbon nanotube composites
Authors: Chakraborty G. , Ghatak S. , Meikap A. K. , Woods T. , Babu R. , Blau W. J. 
Published: June 2010

AbstractPolyaniline/multiwalled carbon nanotube (PANI/MWNT) composites were prepared by in situ polymerization. Scanning electron microscope, X‐ray diffraction, Fourier transform infrared, Uv‐Visible spectroscopy, Fluorescence spectrophotometry were done to characterize the PANI/MWNT composites. Thermal stability was measured by thermogravimetry analysis. The thermal stability of PANI/MWNT composites becomes higher than PANI. Electrical transport properties of different PANI/MWNT composites were investigated in the temperature range 77 ≤ T ≤ 300 K with and without magnetic field up to 1 T. The dc resistivity of PANI/MWNT composites shows different behavior compared to the sample without MWNT. The room temperature dc magnetoconductivity of the samples is negative; however, its sign changes to positive by lowering the temperature, which has been explained by hopping type charge transport. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1767–1775, 2010
Streaming birefringence of polymer solutions
Authors: Philippoff W. 
Published: June 2010

AbstractStreaming or flow‐birefringence is the optical anisotropy induced by laminar flow in liquids. The optical anisotropy can lie described by an optical tensor which is coaxial with the stress tensor in an elastic material In a tension experiment this is obvious. In laminar flow this has been proved by investigating the distribution of the birefringence in three directions of space. The amount of anisotropy, usually described by the degree of birefringence Δn, is proportional to the difference in principal stresses of the mechanical stress tensor in a very large range of variables, therefore giving the possibility of using optical measurements for the determination of mechanical stresses. However, the relationship is valid either for concentrated solutions or for conditions where the solvent and the polymer have essentially the same index of refraction n—a condition usually termed matching solvent. The proportionality constant between the difference in principal stresses and Δn—the stress‐optical coefficient C—is, as also follows from theory, independent of concentration, shear stress temperature, molecular weight and its distribution, only determined by the structure of the monomer unit and its n. Another quantity in flow birefringence is the so‐called extinction angle which is measured between the direction of the principal optical axis and the direction of flow. A reasonable amount of experimental data has been obtained to show that this angle can be quantitatively correlated with the so‐called “recoverable shear” that is the shear component of the elastic strain tensor in laminar flow. Therefore, the experimental determination of the angle gives a measure of the elastic strain. A survey of the experimental results in the field shows the generalities of this approach in a variety of polymer and solvent systems.
Kinetics of thermal degradation of char‐forming plastics from thermogravimetry. Application to a phenolic plastic
Authors: Friedman Henry L. 
Published: June 2010

AbstractA technique was devised for obtaining rate laws and kinetic parameters which describe the thermal degradation of plastics from TGA data. The method is based on the inter‐comparison of experiments which were performed at different linear rates of heating. By this method it is possible to determine the activation energy of certain professes without knowing the form of the kinetic equation. This technique was applied to fiberglass‐reinforced CTL 91‐LD phenolic resin, where the rate law ‐ (1/we)(dw/dt) = 1018 e−55,000/RT [(w ‐ wf)/w0,]5, nr.−1, was found to apply to a major part of the degradation. The equation was successfully tested by several techniques, including a comparison with constant temperature data that were available in the literature. The activation energy was thought to be correct within 10 kcal.
Form III to form II phase transition of polybutene‐1
Authors: Geacintov C. , Schotland R. S. , Miles R. B. 
Published: June 2010

AbstractThe Form III to Form II transition of crystalline potybutene‐1 at elevated temperature has been observed by differential thermal analysis (DTA), dilatometry, x‐ray diffraction, and photomicrography. DTA thermograma of polybutene‐1 in Form III were found to exhibit endotherms at 94°C., and 110°C, corresponding to the transformation of Form III and melting of Form II, respectively. The origin of an exothermic peak observed at 90°C, is not entirely resolved at the present time. The transition of poly‐biitene‐1 in the Form III modification was also studied by x‐ray diffraction methods. It was shown that the intensity of the peak at 2θ = 12.1°, corresponding to the Form III crystalline phase, begins to decrease in sine at 88°C, while simultaneously the peak at 2θ = 11.7°, corresponding to the Form II modification, starts to grow. The transformation is complete at 98°C. The nature of the Form III to Form II transition of polybutene‐1 is discussed in the paper; two alternative mechanisms are deemed possible: a solid‐solid transition or a transition involving a short‐lived intermediate molten state.
Characterization of stereochemical regulation in polypropylenes
Authors: Woodbrey James C. , Thementozzi Q. A. 
Published: June 2010

AbstractThe high‐resolution proton magnetic resonance (PMR) spectra of very highly isotactic, very highly syndiotactic, and stereoblock polypropylenes in o‐dichlorobenzene solutions have been examined. The effects of stereoregulation on proton shieldings and some of the complexities of the methylene proton resonances are discussed. Tactic placement contents were determined for several polymers by a method based on the methylene proton resonances. Tactic pair contents were determined for two stereoblock fractions by a method based on the methyl proton resonances. These results revealed much higher stereoblock characters than those determined previously for the same fractions from melting data. All of the PMR results were in very good accord with the results obtained on several polymers by infrared, x‐ray diffraction, and differential thermal analysis. Two highly isotactic polypropylenes, having essentially the same molecular weights and molecular weight distributions and tactic placement contents differing by no more than the PMR experimental error in precision of ±2%, were shown to have significantly different modulus‐temperature characteristics when identically drawn and annealed. Though such variations in moduli must stem from differences in orystal‐lizabilities, and thus also in stereo regularities, present results do not permit a clear interpretation of the variations in moduli in terms of differences in tactic placement contents or stereoblock characters.
Review of solution methods and certain other methods of polymer fractionation
Authors: Schneider Nathaniel S. 
Published: June 2010

AbstractDiscrimination in terms of solubility differences forms the basis of the most widely applicable methods of polymer fractional ion. These include fractional precipitation and extraction on a batch scale; the rapid column methods, namely, the elution method and precipitation chromatography; and turbidimetric titration, which is strictly an analytical procedure. The principles of solution fractionation are reviewed as applied to batch fractionation and to the column methods, and certain essential differences are pointed out between these two approaches. The importance of proper solvent selection in the several methods is considered, and examples are presented of fractionation on the basis of chemical and structural differences as well as in terms of molecular weight. A brief summary is also presented on the present status of certain other methods, including thermal diffusion, none refining, and adsorption chromatography, which utilize different physical principles as the basis of separation.
Diffusion of penetrants in polymers
Authors: Frisch H. L. 
Published: June 2010

AbstractMany anomalous features of the diffusion of penetrants into polymers, around and below the glass transition, such as the occurrence of history‐dependent diffusion coefficients, sigmoid and “two‐stage” sorption, and time‐dependent boundary conditions, can be shown by non‐equilibrium thermodynamics to be consequences of a simple model of a glasslike transition. Below the transition temperature the system is viewed as undergoing a generalized relaxation with respect to certain characteristic internal variables of even tensorial rank, while above the transition temperature the system is viewed to be in internal equilibrium with respect to these variables. It is pointed out that the mechanism of Fickian diffusion above the glass transition may depend on the distribution of sizes of cavities, particularly the mean cavity volume, as well as the total free volume of the system.
The acidic groups in wood and pulp as measured by ion exchange
Authors: Sjöström Eeho , Janson Tax , Haglund Per , Enström Barbuo 
Published: June 2010

AbstractThe ion‐exchange capacities were determined for a variety of wood samples consisting of both softwood and hardwood. The experiments revealed that considerably more acidic groups are present in heartwood than in sapwood. The capacity (carboxyl) values found for all samples were substantially lower than would be expected from the estimated uronic acid contents. This difference was more striking for hardwood than for softwood. After alkali treatment (pH 11.5, 64°C), the exchange capacity of the wood was increased considerably and this effect was more pronounced for hardwood than for softwood. This observation either indicates the presence of carboxylic acid estera and lactones or is attributable to an increased accessibility of carboxyls. Such an increase may occur in hardwood as a consequence of the deacetylation of xylan. In another series of experiments the effect of sulfonation was studied. Wood samples (Picea abies, Betula verrucosa, and Betula pubescens) were sulfonated at various pH values at 80 and 90°C. so that only small quantities of the wood substance were dissolved. In addition, the number of acidic groups was determined for a series of spruce and birch pulps with varying lignin contents. It was possible to distinguish between the carboxyl and sulfo groups by means of an ion‐exchange method developed for that purpose. The experiments revealed that the accessibility of carboxyl groups is considerably increased even after sulfonation at a low temperature. It also became apparent that most of the carboxyl groups are accessible even in pulps with relatively high lignin contents. The carboxyl values together with xylose analyses showed that the acidity of xylan remaining in pulp is substantially decreased during cooking. This decrease is more pronounced for birchwood than for sprucewood. Finally, it is evident from these experiments that sprucewood lignin is sulfonated to a markedly higher degree than birchwood lignin.
Comparison of the configuration of β‐1,4 linked hexosans and wood xylan pentosans by means of the eizner‐ptitsyn viscosity equations
Authors: Swenson Harold A. , Schmitt Charles A. , Thompson Norman S. 
Published: June 2010

AbstractThe Porod‐Kratky persistence lengths, monomer and polymer radii, and Flory coefficients of a number of β0–1,4 linked hexosans have been compared to each other and to the β‐1,4 linked xylan pentosans of wood by applying the Eizner‐Ptitsyn viscosity equations to intrinsic viscosity and molecular weight analyses from a number of sources. The analyses were made on fractions of cellulose acetate, cellulose nitrate, cellulose caproate, the diethylacetamide derivative of cellulose xanthate, cellulose in cadoxene and in the alkaline ferric tartrate solvent, FeTNa, the galactomannan triacetate of guar, and the glucomannan triacetate of orchid salep tuber. Xylans from spruce and birch, polystyrene, and a branched dextran were also investigated. The persistence lengths of the hexosan derivatives, except the cellulose trinitrate, were remarkably similar and were found to vary from 48 A. for the cellulose caproate determined under theta conditions to 58 A. for the galactomannan triacetate. The persistence lengths of cellulose in the two complexing solvents (72 A.) were nearly identical, confirming that these solvents do not increase the solution dimensions of cellulose greatly. The configuration of the polymers were ranked on a common graph by plotting the log of the polymer radii to contour length ratios vs. the log of the contour length. The investigation shows that the 0–1,4 linked hexosans have a common configuration which is independent of the length of the derivative side group or of single α‐1,6 linked side groups, as in the galactomannan. The configuration of the hexosans is also independent of whether the main chain is composed of glucose or mannose, or a mixture of these sugars. The greater rigidity of the hexosans, in comparison to the pentosans, is explained in the former by hindrance between the C2 group of the one sugar with the C6 group of the next, which is absent in the pentosan that has no C6. Analogy is made to the hindered racemization in substituted biphenyls to explain the great rigidity of cellulose trinitrate, whose persistence length is 132 A.
The number‐average molecular weight of native hardwood xylans
Authors: Koshijima T. , Timell T. E. , Zinbo M. 
Published: June 2010

AbstractA 4‐O‐methylglucuronoxylan has been isolated in a yield of 90% by direct alkaline extraction of trembling aspen (Populus tremuloides) wood. The number‐average molecular weights of the acetate and valerate derivatives were determined in chloroform‐ethanol and of the xylan itself in dilute cupriethylenediamine. There was no evidence for the occurrence of molecular association of the acetate in chloroform‐ethanol. Tetra‐chloroethane, dimethyl sulfoxide, and cadoxen were unsuitable solvents. The results showed that the polysaccharide had a number‐average molecular weight of 31,500, corresponding to a degree of polymerization of 200. The constants K and a in the Staudinger‐Mark‐Houwink equation were determined for cupriethylenediamine solutions of a series of celluloses and xylans, the values obtained being 2.2 × 10−2 for K in both cases, and 0.78 and 0.72 for a, respectively. It was concluded that cellulose and xylan probably have the same conformation in aqueous alkali, intermediate between a compact and a free‐draining coil. Since the xylan framework is known to contain two branches per average molecule, the results would probably also imply that the branches are relatively short.
Chain folding in oriented nylon 66 fibers
Authors: Dismore Paden F. , Statton W. O. 
Published: June 2010

AbstractWhen heated to high temperatures under zero tension, some of the molecules in oriented nylon 66 filters change from the elongated to the folded conformation, with no change in crystal orientation. This transformation is shown by a combination of structural and physical property measurements: wide and small angle x‐ray diffraction, broad and narrow line nuclear magnetic resonance, sonic modulus, density, shrinkage, and tensile properties. A fortyfold increase of the intensity of the discrete small angle x‐ray diffraction is obtained for treatments between 160‐and 255°C. as well as an increase of the length of the long period and a change from a smeared four‐point to a sharp two‐point diagram. Wide angle x‐ray measurements show little change in crystallite orientation for treatments up to 250°C. even though much shrinkage occurs. Disruption of some type is observed by sonic measurements, as would be expected if new folds occurred. An increase of density and x‐ray crystallinity confirms that heating causes much additional crystallization. The high temperature NMR spectra for these more crystalline yarns show a much larger proportion of fluidlike segments. Shrinkage of the yarns during the heating appears to be governed by the number of folds which are introduced. Tensile strength is reduced by this introduction of folded chains.
Multiple mechanical relaxation phenomena in human hair
Authors: Wall Robert A. , Morgan Donald A. , Dasher G. F. 
Published: June 2010

AbstractStress relaxation following small tensile strain was measured for samples of normal, bleached, and permanent‐waved hair immersed in water. The measurements covered up to six decades of log time and were carried out at temperatures from 30 to 85°C. Approximation to the distributions of mechanical relaxation times show a good deal of partially resolvable fine structure. Some of the experimental distributions can be approximated by a small number of Maxwell models in parallel. The different modes of relaxation in a given sample appear to have different temperature shift factors and hence different energy requirements. The effects of bleaching are quite easily seen from the relaxation spectra, whereas the effects of permanent waving, although noticeable, are not as pronounced‐ Proposals for the mechanism of some of the modes of relaxation involve backbone conformational changes of amino acid residues. A large‐scale relaxation is found in bleached hair at temperatures from 60 to 85°C. Perhaps this involves an extensive helix‐coil transformation.