bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of amidoximated poly(glycidyl methacrylate) microbeads
Authors: Caykara Tuncer , Çakar Ferhat , Demirci Serkan 
Published: September 2010

AbstractPoly(glycidyl methacrylate) (PGMA) microbeads were synthesized by a simple suspension polymerization of glycidyl methacrylate and ethylene glycol dimethacrylate. The epoxy groups of the microbeads were firstly modified with 3,3′‐iminodipropionitrile (IDPN) and the resulting nitrile groups were then converted to amidoxime. From scanning electron microscopy studies, the average size of the PGMA microbeads was determined as 170 µm, which was not changed by the modification processes. For the modification of epoxy groups with IDPN, the intensity of the C≡N absorption band at 2249 cm−1 increased proportionally with reaction time; for the conversion of nitrile groups to amidoxime, it decreased. Attenuated total reflectance Fourier transform infrared spectroscopy measurements clearly showed the disappearance of the original nitrile groups and the formation of amidoxime groups through treatment with hydroxylamine under the reaction conditions specified. The microbeads possessed good thermal and morphological properties and chemical stability suitable for practical use. Therefore, the amidoximated PGMA microbeads could be used in batch and continuous processes for the adsorption of uranyl ions from seawater or aqueous media. Copyright © 2010 Society of Chemical Industry
Synthesis of pH‐ and temperature‐responsive chitosan‐graft‐poly[2‐(N,N‐dimethylamino) ethyl methacrylate] copolymer and gold nanoparticle stabilization by its micelles
Authors: Yuan Weizhong , Zhao Zhengda , Yuan Jinying , Gu Shuying , Zhang Fengbo , Xie Xuming , Ren Jie 
Published: September 2010

AbstractNovel pH‐ and temperature‐responsive chitosan‐graft‐poly[2‐(N,N‐dimethylamino)ethyl methacrylate] (chitosan‐g‐PDMAEMA) copolymers were successfully synthesized by homogeneous atom transfer radical polymerization (ATRP) under mild conditions. Chitosan macroinitiator was prepared by phthaloylation of amino groups of chitosan and subsequent acylation of hydroxyl groups of chitosan with 2‐bromoisobutyryl bromide. The copolymers were obtained by ATRP of 2‐(N,N‐dimethylamino)ethyl methacrylate and they can self‐assemble into stable micelles in water. Hybrid micelles with a PDMAEMA corona incorporating gold nanoparticles (Au NPs) were prepared in situ via the reduction of HAuCl4 with NaBH4. The pH and temperature responses of the copolymer micelles and hybrid micelles were characterized using UV‐visible spectroscopy and dynamic laser light scattering. The morphology of the micelles was observed using transmission electron microscopy and atomic force microscopy. The PDMAEMA corona of the micelles acts as the ‘nanoreactor’ and the ‘anchor’ for the in situ formation and stabilization of Au NPs. Therefore, the spatial distribution of Au NPs within the micelles can be tuned by varying the temperature and pH value. Copyright © 2010 Society of Chemical Industry
Thermal Behavior of Nitrocellulose with Inorganic Salts and their Mechanistic Action
Authors: Katoh Katsumi , Higashi Eiko , Nakano Katsuyuki , Ito Shunsuke , Wada Yusuke , Kasamatsu Junichi , Miya Hiroshi , Yamamoto Masaaki , Wada Yuji 
Published: September 2010

AbstractIn this study, we investigated the effects of inorganic salts on the stability of NC and its reaction mechanism. Under isothermal conditions at 120 °C in an O2 atmosphere, the induction time period for NC heat release was prolonged in the presence of Li2CO3, Na2CO3, CaCO3, Mg(OH)2, Ca(OH)2, and MgO, all of which produce alkaline saturated solutions with a pH value of 10–12. In addition, the induction time period depended on this pH value. This suggests that these salts stabilized NC by neutralizing acids that would otherwise accelerate the hydrolysis of the O‐NO2 bond. However, Sr(OH)2 ⋅ 8H2O and K2CO3, which produce strongly alkaline saturated solutions with pH>13, decreased the induction time period. It is possible that these strong bases caused alkaline decomposition of NC. In addition, for Sr(OH)2 ⋅ 8H2O, the released water of crystallization appeared to be related to NC destabilization. SrCO3, NaHCO3, K2SO4, CaSO4, ZnSO4, NaCl, CaCl2, AgCl, and NaNO2, which produce near‐neutral saturated solutions, slightly decreased the NC induction time period. The NC induction time period with these salts depended upon the solubility of the added salt. This may indicate that in the presence of these inorganic salts, the boiling point of water is increased, which reduces the vaporization of water from NC and thus accelerates the hydrolysis of NC.
Knudsen Effusion Measurement of Organic Peroxide Vapor Pressures
Authors: Damour Paul L. , Freedman Andrew , Wormhoudt Joda 
Published: September 2010

AbstractThe vapor pressures of TATP over the temperature range 269.85–306.95 K and DADP over the temperature range 265.85–294.85 K were determined using a modified Knudsen effusion apparatus. The Clausius‐Clapeyron plot of log10(p(Pa)) with 1/T provided a straight line for each material. This expression for TATP is log10(p(Pa))=−(4497±80)/T(K)+(15.86±0.28) (error limits are 95 % confidence limits) and for DADP it is log10(p(Pa))=−(4417±137)/T(K)+(16.31±0.48). These expressions yield values of the vapor pressure at 298.15 K of 6 Pa for TATP and 17 Pa for DADP, and heats of sublimation of 86.2±1.5 kJ mol−1 for TATP and 84.6±2.6 kJ mol−1 for DADP. Attempts were made to determine the vapor pressure of HMTD but it appears to have a vapor pressure too low for our system to reliably determine. A two month experiment did provide an upper limit estimate for the vapor pressure of HMTD of approximately 0.04 Pa at room temperature. Melting point and melting point range were used as verification of the identity and purity of the TATP and DADP used in these experiments, but this was not possible with HMTD since it detonates prior to melting.
Increasing the Utility of the Copper Cylinder Expansion Test
Authors: Lindsay C. Michael. , Butler George C. , Rumchik Chad G. , Schulze Ben , Gustafson Ryan , Maines Warren R. 
Published: September 2010

AbstractWe report the development of a new methodology for analyzing CYLEX tests streak images. In these tests, the displacement of the wall of an explosive filled cylinder is obtained by backlighting the cylinder. The profile is imaged through a slit and streaked across a film record as the cylinder is detonated. A critical step in processing this data is the spatial calibration of the film and extraction of the profile of the cylinder from the image. Historically this has been a tedious task as it was performed by eye with the assistance of an optical comparator. Recently we developed an algorithm which automates the data calibration and extraction process of digitized streak records utilizing the Shen‐Castan edge detection algorithm and the image processing capabilities found in the IGOR PRO software. The new processing methodology greatly increases the resolution of the data, removes human subjectivity, and reduces analysis time from hours to seconds. The higher resolution of the new method has enabled much greater accuracy in measuring early‐time (<15 µs) expansion. With the aid of CTH hydrocode calculations, new fitting functions were developed to model both the early and late‐time expansion data. These functions contain physically meaningful fitting parameters and include terms which mimic the intensity and time scales of the shock and gas induced expansion of the cylinder independently. We demonstrate the methodology and hydrocode calculations on a recent CYLEX test series aimed at examining the effects of a plastic liner on high‐purity oxygen‐free copper cylinders filled with a high explosive.
Semiochemicals of the common bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), and their potential for use in monitoring and control
Authors: Weeks Emma NI , Birkett Mike A , Cameron Mary M , Pickett John A , Logan James G 
Published: September 2010

AbstractThe recent resurgence of the common bed bug, Cimex lectularius L., has driven an increase in research into the biology and behaviour of this pest. Current control is reliant on the application of insecticides, but, owing to the development of insecticide resistance, there is a need for new tools and techniques. Semiochemicals (behaviour‐ and physiology‐modifying chemicals) could be exploited for management of bed bugs. The aim of this review was to evaluate studies undertaken in bed bug chemical ecology to date, with particular reference to how the research could be exploited for monitoring and control. Bed bugs, like many other insects, have a complex olfactory system. Recent studies have characterised the olfactory sensilla, located on the terminal segment of the antennae, to functional classes by electrophysiological screening. Behavioural studies have revealed the presence of an alarm pheromone and potential airborne aggregation semiochemicals, but it is not yet understood if bed bugs use a sex pheromone during mating. Host location cues have been investigated, and carbon dioxide has been found to be highly attractive both in laboratory and in field studies. Recent field trials have tested blends of other potential kairomones, which have been shown to have an additive effect when used in a heated bed bug trap with carbon dioxide. The trap, which combines heat and kairomones, is the only trap currently available with proven efficacy in the field. In order for semiochemicals to be useful for bed bug management, an increased knowledge and understanding of the biology, behaviour and chemical ecology of this insect is essential. Copyright © 2010 Society of Chemical Industry
Chirality dependence of the dielectric constant for the excitonic transition energy of single‐wall carbon nanotubes
Authors: Araujo P. T. , Nugraha A. R. T. , Sato K. , Dresselhaus M. S. , Saito R. , Jorio A. 
Published: September 2010

AbstractAttention has been devoted recently to understand the physics behind the dielectric screening of the carbon nanotube optical transitions (Eii), including how a changing environment changes Eii. It was shown that the environmental screening could be modeled by an effective diameter dependent dielectric constant κ, which takes into account contributions from the single‐wall carbon nanotube (SWNT) itself and from the environment surrounding the tube. Here we consider the chiral angle (θ) dependence of κ which improves the previous fitting by only the diameter dependence and we can now see the difference between $E_{11}^{M} $ and $E_{22}^{S} $ by the present treatment. In this work we used the “alcohol‐assisted” and the “super‐growth” SWNT samples to address this point.
Polarised Raman measurements of β‐carotene encapsulated in SWNTs
Authors: Brose Katharina , Tschirner Norman , Zouni Athina , Müh Frank , Yanagi Kazuhiro , Kataura Hiromichi , Thomsen Christian , Maultzsch Janina 
Published: September 2010

AbstractThe knowledge of the vibrational properties is of key importance to understand their function of β‐carotene molecules in the reaction centre of the light‐harvesting complexes. We present polarisation‐dependent Raman spectroscopy on β‐carotene molecules in two different environments: first single dimeric photosystem II crystal, and second encapsulated β‐carotene in single‐wall carbon nanotube bundles. Both systems have nearly perpendicular or parallel orientated β‐carotene molecules. We compare the dependence of their Raman spectra on the polarisation of incident and scattered light.
Size dependence of the magnetic response of graphite oxide and graphene flakes – an electron spin resonance study
Authors: Ćirić Luka , Sienkiewicz Andrzej , Djokić Dejan M. , Smajda Rita , Magrez Arnaud , Kaspar Tommy , Nesper Reinhard , Forró László 
Published: September 2010

AbstractWe employed electron spin resonance (ESR) technique in the investigation of a series of graphene flakes with different size distributions. Graphene oxide (GO) samples with three distinct size distributions were prepared by the Brodie method. Large flakes of ∼2500 µm2, intermediate size flakes of ∼1 µm2, and small ones of ∼500 nm2 have been characterized by ESR in the 4–295 K temperature range. Already for GO flakes the magnetic response strongly varies with their size. Large GO flakes are inhomogeneous, revealed by the presence of both Pauli and Curie components in the overall signal. In small GO flakes ESR spin susceptibility reveals superparamagnetic behavior ascribed to interaction between localized spins. The intermediate flakes show a standard Curie behavior showing a uniform oxidation and the concomitant non‐interacting localized spins. On this batch a thermal method of reduction was applied such that in polar solvent the suspension of GO was heat treated at temperatures below 200 °C. ESR susceptibility shows that this reduction can recover some of the Pauli‐like contribution of the pristine graphene. However, our study shows that the full optimization of oxidation/reduction parameters is yet to be achieved.
Temperature dependence of first‐ and second‐order Raman scattering in silicon nanowires
Authors: Khachadorian S. , Scheel H. , Colli A. , Vierck A. , Thomsen C. 
Published: September 2010

AbstractThe first‐ and second‐order Raman scattering of the silicon nanowires grown without any metal catalyst is studied in the temperature range from 77 to 873 K. The first‐ and second‐order Raman peaks were found to shift and broaden differently with increasing temperature. We show that this is due to the confinement related enhanced anharmonic effects in silicon nanowires. Our measurements also show that both the second‐ to first‐order Raman peak intensity ratio [I(2TA)int./I(1TO)int. and I(2TO)int./I(1TO)int.] and the Raman relative intensities [I(2TA)int./I(2TO)int.] increase with increasing temperature.
magnified imageTEM image of SiNWs. The SiNW are 15 nm in diameter and up to a few microns long.
Synthesis and functionalization of chalcogenide nanotubes
Authors: Tahir Muhammad Nawaz , Yella Aswani , Sahoo Jugal Kishore , Annal‐Therese Helen , Zink Nicole , Tremel Wolfgang 
Published: September 2010

AbstractNew synthetic approaches to MS2 (M = Sn, Nb, Mo, W) chalcogenide nanostructures are highlighted. Most chalcogenide particles can be functionalized directly with inorganic nanoparticles such as Au, ZnO or MnO. Depending on the Pearson hardness of the metal involved, the functionalization may be reversible or irreversible. A covalent functionalization strategy is based on a steric shielding of the coordination sphere of transition metal atoms in such a way that only coordination sites are available for bonding to the chalcogenide surface. This allows the immobilization of fluorophors, redox active groups or proteins onto chalcogenide nanoparticle.
magnified image
Auxeticity of cubic materials under pressure
Authors: Brańka A. C. , Heyes D. M. , Wojciechowski K. W. 
Published: September 2010

AbstractThe global maximum and global minimum Poisson's ratio (PR) surfaces, regions of different auxetic behaviour and the domains of the different extreme directions of cubic materials are shown and discussed in terms of the elastic moduli ratios, $X = G/K,Y = G/W$, where K is the bulk modulus and $G,W$ are shear moduli. A straightforward way is given to classify any cubic material as being auxetic, nonauxetic and partially auxetic, as well as calculating its extreme PR values. A decomposition of the XY plane with the elastic constant ratio ${\lambda} = C_{12} /C_{44} $ is introduced to facilitate the interpretation of cubic materials under hydrostatic pressure, $P> 0$, and isotropic tension, $P< 0$, which are two qualitatively different situations. Using this representation it is demonstrated that cubic materials with ${\lambda} > 0$ can be auxetic only under ‘negative’ pressure ($P< 0$). It is shown that the influence of pressure on the auxetic behaviour is different for the positive and negative ${\lambda} $ cases. In particular, a cubic material with $0> {\lambda} > {-} 1$ may be auxetic at negative as well as positive pressure. The work demonstrates the crucial role of P in obtaining desired auxetic behaviour. Microscopic mechanisms which tune the cubic system to targeted regions in the XY plane are investigated with a fcc crystal of particles interacting via the pairwise spherically symmetric potential, ${\phi} (r)$. It is found that all fcc static models in which the range of interaction is only between nearest neighbour particles are placed on a universal curve in the XY plane. It is shown that auxetic behaviours can be achieved with simple static ${\phi} (r)$ analytic forms. The influence of the next neighbour interactions on the universal curve is also considered. In order to assess the role of thermal fluctuations, molecular dynamic simulations for two different ${\phi} (r)$ (the Lennard–Jones (LJ) and the tethered particle potentials) were performed. At low temperatures the studied systems are well represented by the universal curve and on increasing temperature a systematic departure from it is observed.
Unusual deformation mechanisms in carbon nanotube heterojunctions (5,5)–(10,10) under tensile loading
Authors: Scarpa F. , Narojczyk J. W. , Wojciechowski K. W. 
Published: September 2010

AbstractThe Poisson's ratio effect of single wall carbon nanotube heterojunctions (HJ) of the type (5,5)–(10,10) is investigated using an hybrid finite element atomistic‐continuum approach to simulate the mechanical behaviour of nanostructures. The nanotube HJs provide a peculiar deformation pattern, with combined bending and axial stretching of carbon nanotubes (CNTs), and a broad agreement of their axial stiffness with spring series continuum mechanics and existing molecular dynamics (MD) simulations. A possible auxetic behaviour is observed for the pure HJ with no tubes when subjected to tensile loading.
Flexible resistance memory devices based on Cu/ZnO:Mg/ITO structure
Authors: Shi Lei , Shang Da‐Shan , Sun Ji‐Rong , Shen Bao‐Gen 
Published: September 2010

AbstractResistance memory devices based on a Cu/Mg‐doped ZnO/indium‐tin‐oxide structure on a PET (polyethylene terephthalate) flexible substrate were fabricated. The devices showed stable bipolar resistance switching property and good flexibility. The high to low resistance ratio was larger than 30 times, the endurance was more than 102 cycles, and the resistance retention was longer than 104 s. The resistance values of both high and low resistance states were not significantly changed by bending in a radius (≥20 mm) for more than 103 times. This resistance switching phenomenon of our devices can be explained by creation/rupture of metal conductive channels induced by electrochemical migration of Cu ions. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Learning in the Field: Using Community Self Studies to Strengthen Forest‐Based Social Movements
Authors: Taylor Peter Leigh , Cronkleton Peter , Barry Deborah 
Published: September 2010

AbstractState devolution has combined with social movement pressures to give communities increasing access and rights to southern forests, making development of effective local participation in sustainable resource management crucial. This paper discusses an experience of participatory research in Central America, which sought to help two grassroots forest organizations, the Association of Forest Communities of Petén, Guatemala and the Farmer to Farmer Programme of Siuna, Nicaragua, to respond to new organizational and political challenges by developing their internal capacity for research and analysis. Community‐based ‘para‐professional’ social researchers were trained to carry out studies of their communities' experiences with natural resource management, including strengths, problems and possible response strategies. The collaborative research initiative also encountered problems of inequality, uneven education and skills and concerns with validity. The results of this experience indicate that with appropriate support, community‐based research and researchers can help engender collective reflection, strengthen local organizational capacity and contribute knowledge and analysis in support of forest community movements' efforts to promote local resource rights and more sustainable development. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment.
Comments on Brodie and Post: Climate‐driven declines in wolverine populations: causal connection or spurious correlation?
Authors: McKelvey Kevin S. , Lofroth Eric C. , Copeland Jeffrey P. , Aubry Keith B. , Magoun Audrey J. 
Published: September 2010

AbstractThe recent paper by Brodie and Post (“Nonlinear responses of wolverine populations to declining winter snowpack”, Popul Ecol 52:279–287, 2010) reports conclusions that are unsupportable, in our opinion, due to both mis‐interpretations of current knowledge regarding the wolverine's (Gulo gulo) association with snow, and the uncritical use of harvest data to index wolverine populations. The authors argue that, because the wolverine is a snow‐dependent species, average annual provincial snowfall, based on weather station data, can be expected to correlate strongly and positively with wolverine population numbers, which in turn can be accurately indexed by trapper harvests. Thus, correlations between declines in wolverine harvests and declining average snowpack are interpreted to reflect a climate‐driven decrease in wolverine populations. This conclusion overstates the nature of the wolverine's association with snow, and makes unsupportable assumptions about the reliability of harvest data as a proxy for population size.
Are exotic invaders less susceptible to native predators? A test using native and exotic mosquito species in New Zealand
Authors: Zuharah Wan Fatma , Lester Philip John 
Published: September 2010

AbstractA major hypothesis in invasion ecology is that native predators have less impact on exotic relative to native prey species. Here, we tested this hypothesis by examining the New Zealand native predatorAnisops wakefieldiconsuming native (Culex pervigilans) and exotic (Aedes notoscriptus) mosquito larvae.Anisops wakefieldiexhibited a decelerating type II functional response for both prey species, but at high prey densities consumed more of the exotic mosquitoAe. notoscriptus. A significantly higher attack rate was observed for the native predator feeding on exotic species. In the presence of both prey species, the predator showed preferences towardsAe. notoscriptusand demonstrated switching behavior towards this exotic species. The preference of the native predator towards the exotic mosquito appeared related to behavioral differences between the two prey species. We tested the behavioral response of both mosquito species in four conditions; (1) control (without predators), (2) free‐roaming predators, (3) caged predators, and (4) kairomones only. Resting activities at the water surface and wall positions were the most frequently behaviors exhibited byCx. pervigilansin the presence of predator. In contrast, the exotic speciesAe. notoscriptusdemonstrated significantly higher levels of “thrashing” behaviors, apparently making itself more obvious to the predators. The behaviors showed byCx. pervigilansfulfilled the “threat sensitivity hypothesis”. No evidence here supported the idea that exotic mosquito species are less prone to the influence of native predators and the “escape from natural enemies” hypothesis seems not apply in our study. In fact, we observed that this invader was more susceptible to the predator.