bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for rapid ice flow and proglacial lake evolution around the central Strait of Magellan region, southernmost Patagonia
Authors: Lovell Harold , Stokes Chris R. , Bentley Michael J. , Benn Douglas I. 
Published: June 2012

AbstractThis paper presents a detailed palaeoglaciological reconstruction of ice sheet dynamics in the Seno Skyring, Seno Otway and Strait of Magellan region of the former Patagonian Ice Sheet, with a particular focus on previously hypothesised zones of rapid ice flow and the evolution of proglacial lakes. Geomorphological mapping from a combination of satellite imagery and oblique and vertical aerial photographs reveals a variety of glacial landforms that are grouped into several discrete flow‐sets and associated ice margin positions. The most distinct features are represented by flow‐sets of highly elongate streamlined glacial lineations on both sides of the Strait of Magellan. Based on the shape and dimensions of the flow‐sets and their abrupt lateral margins, a transverse and longitudinal variation in glacial lineation length and elongation ratio, and the reported presence of a potentially deformable bed and thrust moraines, the flow‐sets are interpreted as zones of rapid ice flow within the Otway and Magellan lobes. We hypothesise that this provides evidence for contemporaneous surge‐like advances within the lobes, which may explain the asymmetry in the lobate margin positions on either side of the strait. The mechanisms that initiated rapid flow are unclear, but are likely to have been influenced by internal factors such as a change in thermal/hydrological conditions at the bed. The topography of the region suggests ice‐dammed lakes would have formed as the ice lobes retreated. The westernmost of the former lakes, Lake Skyring, is delimited by a series of palaeo‐shorelines surrounding the present‐day lake Laguna Blanca and we reconstruct lake evolution based on manipulation of a digital elevation model. The size and orientation of meltwater channels and a large outwash plain indicate that Lake Skyring drained eastwards towards the Strait of Magellan, probably quite rapidly. We conclude that the potential for quasi‐independent surge‐like behaviour within adjacent lobes raises the possibility that, during climate‐driven ice expansion, some advances in this region may have been partly controlled by secondary internal feedback mechanisms. Copyright © 2012 John Wiley & Sons, Ltd.
Potential of powdered activated mustard cake for decolorising raw sugar
Authors: Singh Kaman , Bharose Ram , Verma Sudhir Kumar , Singh Vimalesh Kumar 
Published: June 2012

AbstractBACKGROUND: Carbon decolorisation has become customary in the food processing industries; however, it is not economical. Extensive research has therefore been directed towards investigating potential substitutes for commercial activated carbons which might have the advantage of offering an effective, lower‐cost replacement for existing bone char or coal‐based granular activated carbon (GAC).RESULTS: The physical (bulk density and hardness), chemical (pH and mineral content) and adsorption characteristics (iodine test, molasses test and raw sugar decolorisation efficiency) of powdered activated mustard cake (PAMC) made from de‐oiled mustard cake were determined and compared to commercial adsorbents. Although the colour removal efficiency of the PAMC is lower than that of commercial materials, it is cost effective and eco‐friendly compared to the existing decolorisation/refining processes. To reduce the load on GAC/activated carbon/charcoal, PAMC could be used on an industrial scale. A decolorisation mechanism has been postulated on the basis of oxygen surface functionalities and surface charge of the PAMC and, accordingly, charge transfer interaction seems to be responsible for the decolorisation mechanism. In addition, a complex interplay of electrostatics and dispersive interaction seem to be involved during the decolorisation process.CONCLUSION: A low‐cost agricultural waste product in the form of de‐oiled mustard cake was converted to an efficient adsorbent, PAMC, for use in decolorising raw as well as coloured sugar solutions. The physical, chemical, adsorption characteristics and raw sugar decolorisation efficiency of PAMC were determined and compared to those of commercial adsorbents. The colour removal efficiency of the PAMC is lower than that of commercial materials but it is cost effective and eco‐friendly as compared to existing decolorisation/refining processes. The availability of the raw material for the production of PAMC further demands its use on an industrial scale. Copyright © 2012 Society of Chemical Industry
Drying and processing protocols affect the quantification of cyanogenic glucosides in forage sorghum
Authors: Gleadow Roslyn M , Møldrup Morten E , O'Donnell Natalie H , Stuart Peter N 
Published: June 2012

AbstractBackground: Cyanogenic glucosides are common bioactive products that break down to release toxic hydrogen cyanide (HCN) when combined with specific β‐glucosidases. In forage sorghum, high concentrations of the cyanogenic glucoside dhurrin lead to reduced productivity and sometimes death of grazing animals, especially in times of drought, when the dhurrin content of stunted crops is often higher. The aim of this study was to develop harvesting protocols suitable for sampling in remote areas.Results: Dhurrin concentration in air‐ and oven‐dried leaves was the same as in fresh leaves, with no subsequent losses during storage. Dhurrin concentration was halved when leaves were freeze‐dried, although activity of the endogenous dhurrinase was preserved. Direct measurement of dhurrin concentration in methanolic extracts using liquid chromatography/mass spectrometry (LC/MS) gave similar results to methods that captured evolved cyanide. A single freezing event was as effective as fine grinding in facilitating complete conversion of dhurrin to cyanide.Conclusion: Direct measurement of dhurrin using LC/MS is accurate but expensive and not appropriate for fieldwork. Air drying provides an accurate, low‐cost method for preparing tissue for dhurrin analysis, so long as the specific β‐glucosidase is added. It is recommended that comparative studies like the one presented here be extended to other cyanogenic species. Copyright © 2012 Society of Chemical Industry
A Polyurethane Surface Modifier: Contrasting Amphiphilic and Contraphilic Surfaces Driven by Block and Random Soft Blocks Having Trifluoroethoxymethyl and PEG Side Chains
Authors: Zhang Wei , Fujiwara Tomoko , Taşkent Hűmeyra , Zheng Ying , Brunson Kennard , Gamble Lara , Wynne Kenneth J. 
Published: June 2012

AbstractA conventional MDI‐BD‐PTMO polyurethane is modified using 2 wt% polyurethanes (U) having copolyoxetane soft blocks with hydrophobic 3F, CF3CH2OCH2— and hydrophilic MEn, CH3O(CH2CH2O)nCH2—, n = 3, 7) side chains. In contrast to neat 3F‐co‐MEn‐U, 2 wt% 3F‐co‐MEn‐U compositions have physically stable morphologies and wetting behavior. Surface composition (XPS) and amphiphilic or contraphilic wetting are controlled by the 3F‐co‐MEn polyoxetane soft block architecture and MEn side chain length. Importantly, θrec can be tuned for 2 wt% 3F‐co‐MEn‐U compositions independent of swelling, which is controlled by the bulk polyurethane. AFM imaging leads to a new morphological model whereby fluorous/PEG‐hard block nanoaggregates combine to form near surface features culminating in micron‐scale texturing.
Modification of Microbial Polymalic Acid With Hydrophobic Amino Acids for Drug‐Releasing Nanoparticles
Authors: Lanz‐Landázuri Alberto , García‐Alvarez Montserrat , Portilla‐Arias José , de Ilarduya Antxon Martínez , Holler Eggehard , Ljubimova Julia , Muñoz‐Guerra Sebastián 
Published: June 2012

AbstractMicrobial poly(β,L‐malic acid) was modified with either L‐leucine ethyl ester (L) or L‐phenylalanine methyl ester (F) to produce amphiphylic copolymers. The degradation of these copolymers in aqueous buffer took place under physiological conditions in a few weeks by hydrolysis of the side chain ester group followed by cleavage of the main chain. Spherical nanoparticles with diameters ranging between 70 and 230 nm were prepared from these copolymers by the dialysis‐precipitation method. No alteration of the cell viability was observed after incubation of these nanoparticles in different cell lines. Anticancer drugs temozolomide and doxorubicin were encapsulated in the nanoparticles. Temozolomide was released within several hours whereas doxorubicin took several weeks to be completely liberated.
Wetting Properties of Barium Sodium Niobate Filled Polystyrene Nanocomposite
Authors: Abraham Rosalin , Varughese K. T. , Isac Jayakumari , Thomas Sabu 
Published: June 2012

AbstractNano crystalline powders of Barium Sodium Niobate (BNN) with the composition (Ba3 Na4Nb10 O30) have been prepared by conventional ceramic technique. XRD and SEM studies revealed that its particle size is in the nanometer range. Composites were prepared by mixing powders of BNN with polystyrene at different volume fractions of the material. Melt mixing technique was carried out in brabender plasticoder at a rotor speed of 60 rpm for composite preparation. Surface energy characteristics of the composites are measured using contact angle measurements of the composites with water and methlene iodide. The solid surface free energy is calculated from harmonic mean equations. The results are quantitatively analyzed with Girifalco‐Good empirical model and provide unique insight into its properties. Various wettability parameters such as total solid surface free energy, work of adhesion, interfacial free energy and spreading coefficient are analyzed. The different parameters are calculated from the harmonic mean equation. The work of adhesion and interfacial free energy, spreading coefficient, and Girifalco‐Good's interaction parameter had changed with composition. The surface properties can be controlled for a given polymer‐surface pair by controlling the chemical structure, composition etc.
Interfacial Tension and Width of an Asymmetric Polymer Mixture
Authors: Adhikari Narayan P. 
Published: June 2012

AbstractWe have used continuous space rod‐bead model and an off‐lattice Monte Carlo technique to investigate interfacial properties between two incompatible polymers of different stiffnesses. We have estimated the interfacial tension as well as interfacial width of all the systems studied. Further, by studying the interfacial tension and/or interfacial width in the weak segregation limit one can estimate the critical value of temperature at which two different kinds of polymers mix. In the present work, we have estimated the critical value of temperature at which the polymers mix by studying the interfacial width in the weak segregation limit for the different systems containing the flexible and semi‐flexible polymers of different stiffnesses.
The Effect of Compatibilizer on the Properties of Impact Poly(propylene)‐Wood Composites
Authors: Basson Nicolaas Christiaan , van Reenen Albert 
Published: June 2012

AbstractThe effect of two compatibilizers, polypropylene graft maleic anhydride (PPgMA) and ethylene vinyl alcohol (EvOH), on the physical properties of wood polymer composites were studied. The composites were prepared with pine wood and two different impact polypropylene polymers, where the polymers varied according to ethylene content. These compatibilizers, when used together and pre‐reacted to create a joint compatiblizer of PPgMA and EvOH, significantly improved control over the repeatability of the physical properties tested, compared to when the compatibilizers were used individually. The impact values were slightly reduced, however the standard deviation of these values showed that the variation in the impact properties were significantly minimized when EvOH was also introduced. It appears that the joint compatiblizer provides better control over the hardness to impact balance of these composite materials and some of these physical properties were improved depending on the ratio between PPgMA and EvOH used, in the joint compatibilizer. Due to the difference in chemistry between PPgMA and EvOH, we expected PPgMA to interact more with the crystalline polypropylene matrix of the impact polymer and the EvOH with the amorphous, rubbery part and yield interesting results.
Solvodynamic Properties of Sodium Polystyrenesulfo‐nate in Methanol‐Water Mixed Solvent Media in Absence and in the Presence of a Salt Using Viscometric Method
Authors: Bhattarai Ajaya , Das Bijan 
Published: June 2012

AbstractLinear extrapolation of the reduced viscosity values of uncharged polymer solutions as the concentration approaches zero constitutes the basis for the traditional method for the determination of the intrinsic viscosities of polymer solutions. While this method works well for uncharged polymer solutions, it fails completely for polyelectrolyte solutions especially in absence and also in presence of small amount of an added electrolyte. A very convenient method has recently been proposed by Wolf (Wolf, Macromol. Rapid Commun. 2007, 28, 164) to determine the intrinsic viscosities of polyelectrolyte solutions on the basis of the laws of phenomenological thermodynamics applied to the viscosity of polymer solutions. In spite of the success and the convenience of this method, this has so far been applied to a limited number of polyelectrolyte systems by the Wolf group alone (Wolf, Macromol. Rapid Commun. 2007, 28, 164; Eckelt et al., Macromolecules 2008, 41, 912; Badiger et al., Macromol. Chem. Phys. 2008, 209, 2087; Ghimici et al., J. Phys. Chem.B. 2009, 113, 8020). In order to improve the situation, we have measured the viscosities of an anionic polyelectrolyte, sodium polystyrenesulfonate, in methanol‐water mixed solvent media both in absence and in the presence of an electrolyte, sodium chloride. The results show that the experimental data fit well with the Wolf model and thus allow the calculation of intrinsic viscosities, which provide important insight about the dependence of the polyion conformation on solvent composition as well as on the concentration of the added electrolyte. This new evaluation method, thus, proves to be very useful to a better understanding of the rheological behaviour of the polyelectrolyte system investigated.
Tunneling Effect in Polythiophene
Authors: Kelkar Deepali , Chourasia Ashish , Balasubramanian Venkitarman 
Published: June 2012

AbstractPolythiophene has been chemically synthesized using 2,5– dibromothiophene by debromination with magnesium, catalyzed by nickel chloride. The synthesized polymer was undoped using liquid ammonia and then doped again using 5% (wt/volume) aqueous FeCl3 for 2.5, 5 and 10 hour duration. Characterization of undoped as well as doped samples using elemental analysis and FTIR has been carried out. Elemental analysis shows that concentration of Fe+ atoms increases as the duration of doping increases. The FTIR spectrum reveals the complex formation between FeCl3 and polythiophene. All samples were pressed into pellets of about 1cm in diameter. The pellets were coated with gold (Au) on one side and with aluminum (Al) on other side using vacuum deposition technique. I–V measurements of undoped and FeCl3 doped samples, after coating have been carried out using two probe method. I–V measurements, at room temperature, were carried out by applying d. c. voltage with +ve potential to the side of the pellet coated with Au and –ve potential to Al from 0 V to 1 V in step of 0.01 V and then from 1V to 15 V in step of 0.5 V. The measurements were again carried out after interchanging the polarity of the applied voltage. These characteristics are just similar to the characteristics of conventional tunnel diode in forward bias condition and like Schottky diode in reverse bias condition. Various parameters of tunnel diode such as figure of merit, voltage spread, noise figure etc are calculated using the measurements carried out. Noise figure value of undoped polythiophene is very close to ideal value. The performance of all FeCl3 doped sample reduces, however value of the current ratio Ip/Iv (figure of merit) value for 5 hr. FeCl3 doped polythiophene sample matches with that of silicon (Si) tunnel diode.
Hierarchically Structured Materials for Bone Regeneration: Biomimetic Morphology, Micro‐Mechanics and Properties
Authors: Henning Sven , Imam Khasim H. R. , Michler Goerg H. , Brandt Jörg 
Published: June 2012

AbstractThe contribution describes the development of a biocompatible nanocomposite material consisting of a resorbable polymeric matrix and osteoinductive nanoparticles that can be used to manufacture compact products, porous scaffolds, hybrid nanofibers, and alternating porous/compact structures. It is shown that the material has a good balance of stiffness, strength and toughness. The material supports osteoblast proliferation. Based on a modular design principle, several prototypes for hierarchical 3D constructs are proposed.
Novel Hydrophobic Biodegradable Ester‐Polymers Obtained via Azlactone Chemistry
Authors: Kobauri Sophia , Zavaradshvili Nino , Dgebuadze Marina , Tugushi David , Katsarava Ramaz 
Published: June 2012

AbstractBiodegradable polymers having a potential for constructing resorbable therapeutical micro‐ and nano‐containers were synthesized by interaction of bis‐azlactones with bis‐(L‐leucine)‐1,6‐hexylene diester/1,6‐diamino hexane either separately or as comonomers. The thermograms (DSC) all of them showed a wide endothermal peak within 55–120 °C with a maximum ranged from 86 °C to 96 °C. The peak was assigned to the melting of hydrophobic domains formed by aromatic terephthalic acid fragments in the polymeric backbones. Preliminary in vitro study showed that the ester‐bonds containing polymers obtained are biodegradable – α‐chymotrypsin catalyzed ester bonds hydrolysis rates ranged within 0.02–0.34 µmole/min.
Instrumented Macroindentation Techniques for Polymers and Composites – Mechanical Properties, Fracture Toughness and Time‐Dependent Behaviour as a Function of the Temperature
Authors: Lach Ralf , Schöne Jan , Bierögel Christian , Grellmann Wolfgang 
Published: June 2012

AbstractAn innovative cooling and heating device has been successfully applied to an instrumented macrohardness testing machine in close collaboration with the company Zwick/Roell. The prototype allows the local time‐dependent analysis of mechanical properties such as Martens hardness and indentation modulus, as well as fracture toughness and creep and relaxation behaviour at temperatures ranging from −100 °C to +100 °C. On the basis of load–indentation depth, load–time or indentation depth–time diagrams, the indentation behaviour as a function of test speed and/or temperature (which has rarely been done for polymers in the macro‐range of loading) depending on matrix and materials composition (amorphous/semicrystalline thermoplastics, epoxy resins, micro‐ and nanocomposites) has been analysed. Martens‐hardness, indentation modulus on the one hand and creep compliance and relaxation modulus on the other have been found to be strongly temperature dependent. Adequate methods of indentation fracture mechanics have been enhanced for polymers and applied to determine the fracture toughness of very different polymer‐based materials.
Microdeformation in Poly‐L‐lactide and Poly‐L‐lactide + Hydroxyapatite Nanocomposite Thin Films
Authors: Plummer Christopher J.G. , Choo Caleb K.C. , Delabarde Claire , Månson Jan‐Anders E. 
Published: June 2012

AbstractIn order to gain new insight into failure mechanisms in poly‐L‐lactide (PLLA) and PLLA + hydroxyapatite nanocomposites, transmission electron microscopy has been used to investigate room temperature microdeformation in electron transparent thin films of these materials subjected to various heat treatments and deformed in tension using the “copper grid” technique. In amorphous PLLA the dominant microdeformation mechanism was crazing. Localized fibrillar deformation zones (DZs) were also observed in semicrystalline films, tending to propagate in regions where the lamellar trajectories were at high angles to the tensile axis. Thus, in spherulitic films, in which the lamellae formed well‐defined stacks with approximately straight trajectories at the scale of the spherulite radii, individual DZs were observed to propagate over relatively large distances, as in the amorphous films. On the other hand, films cold crystallized by heating from the glassy state showed more homogeneous lamellar textures. These were associated with a relatively high density of low aspect ratio DZs. Addition of well dispersed nanosized hydroxyapatite (nHA) to the amorphous PLLA films was also found to result in an increase in the craze density, attributed to stress concentrations associated with void formation at the PLLA‐particle interfaces during deformation. However, interpretation was less straightforward in cold crystallized PLLA + nHA thin films, owing to a correlation between the lamellar texture and the nHA particles. In this case, both void formation and favorable lamellar orientations may have contributed to initiation of the DZs in the vicinity of the particles. The results are argued to be broadly consistent with previous observations of the behavior of bulk PLLA and PLLA + nHA films with a range of microstructures, in which there was evidence for an improvement in ductility in the presence of the nHA, again attributed to voiding at the PLLA‐particle interfaces.
The Effect of UV‐Irradiation on Poly(vinyl alcohol) Composites with Bacterial Cellulose
Authors: Stoica‐Guzun Anicuta , Stroescu Marta , Jipa Iuliana , Dobre Loredana , Jinga Sorin , Zaharescu Traian 
Published: June 2012

AbstractThe development of biodegradable packaging materials, especially from renewable resources is a constant preoccupation of nowadays, because of the environmental problems caused by synthetic polymers. The combination of cellulose with other polymeric materials could be an ecologic alternative and a way to use renewable resources for food packaging. Bacterial cellulose which is produced by microbial fermentation is also a promising material which can be used not only in biomedical application, but also as food packaging material. In this research different composite films between poly(vinyl alcohol)‐bacterial cellulose (PVA‐BC) were obtained by casting method. The obtained films were UV irradiated for different periods of times from 1 to 10 hours, using a mercury lamp, Philips TUV‐30, emitting light mainly at 254 nm. Changes in FT‐IR spectra before and after UV irradiation and the modification of transparency and of the swelling characteristics of the films were observed. As it was expected the composites materials are sensitive at UV exposure.
Improvement in Radiation Stability of EPDM by Efficient Antioxidants
Authors: Zaharescu Traian , Jipa Silviu , Henderson David 
Published: June 2012

AbstractThis paper analyses the stabilization effect induced by the presence of several compounds with antioxidant features (oleanolic acid, quercetin, capsaicin, metallic selenium and rosemary extract). The investigation are carried out for different additive concentrations (0, 0.25, 0.50 and 1% w/w), as well as for pairs of metallic selenium with the other four compounds. For antirad contribution to the delaying of radiochemical oxidation, modified and pristine EPDM samples were irradiated in GAMMATOR machinery provided with 137Cs source. While dose rate is 0.4 kGy.h−1, the total doses were 0, 10, 20 and 30 kGy, which are specific for radiosterilization. The results are obtained by application of two complementary techniques: isothermal chemiluminescence (180 °C) and FT‐IR spectroscopy. From chemiluminescence determinations oxidation induction times and rate of oxidation were calculated as the main kinetic characteristics depicting the progress in the oxidative degradation of polymer substrate. FT‐IR spectroscopy allows us to evaluate the evolution of hydroxyl and carbonyl accumulations.