bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultra low density and highly crosslinked biocompatible shape memory polyurethane foams
Authors: Singhal Pooja , Rodriguez Jennifer N. , Small Ward , Eagleston Scott , Van de Water Judy , Maitland Duncan J. , Wilson Thomas S. 
Published: March 2012

AbstractWe report the development of highly chemically crosslinked, ultra low density (∼0.015 g/cc) polyurethane shape memory foams synthesized from symmetrical, low molecular weight, and branched hydroxyl monomers. Sharp single glass transitions (Tg) customizable in the functional range of 45–70 °C were achieved. Thermomechanical testing confirmed shape memory behavior with 97–98% shape recovery over repeated cycles, a glassy storage modulus of 200–300 kPa, and recovery stresses of 5–15 kPa. Shape holding tests under constrained storage above the Tg showed stable shape memory. A high volume expansion of up to 70 times was seen on actuation of these foams from a fully compressed state. Low in vitro cell activation induced by the foam compared with controls demonstrates low acute bio‐reactivity. We believe these porous polymeric scaffolds constitute an important class of novel smart biomaterials with multiple potential applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Plasma Functionalization of Multiwalled Carbon Nanotubes and Their Use in the Preparation of Nylon 6‐Based Nanohybrids
Authors: Scaffaro Roberto , Maio Andrea , Agnello Simonpietro , Glisenti Antonella 
Published: March 2012

AbstractThe possibility to obtain carbon nanotubes (CNT)/polyamide 6 composites with excellent mechanical properties in a simple, industrially scalable way is investigated. Commercial CNTs are treated by plasma while changing some key parameters (exposure time, plasma power, type of gas) in order to optimize the process and to achieve a sufficient degree of functionalization. The treated samples are characterized by Fourier transform infrared spectroscopy, Raman spectroscopy and X‐ray photoelectron spectroscopy. The most interesting samples are selected to be used as reinforcing fillers, in different concentrations, in a polyamide 6 matrix. The mechanical tests show a dramatic increase of both tensile and impact properties, due to the achievement of a good wettability, and an efficient dispersion of the CNTs in the polymer matrix, as confirmed by scanning electron microscopy observations. magnified image
An Electrical Thrombectomy Device Using Plasma Created Chemistry in a Saline Environment to Dissolve Vascular Clots
Authors: Jung Jae‐Chul , Koo Il Gyo , Choi Myeong Yeol , Yu Zengqi , Kim Myung‐Soo , Collins George J. 
Published: March 2012

AbstractAn electrical thrombectomy device, using liquid plasma generated radicals for removing intravascular blood clots, causing either the chronic total occlusion clots or DVT clots, was demonstrated. We employed a proxy experimental clot model of DVT with the blood filled collagen sheets. We also treated a real equine blood clot. Both clot samples were provided by the Veterinary Hospital of Colorado State University. Optical emission spectroscopy was used to examine the relative populations of the reactive chemical species generated by the liquid plasma that drives the clot dissolution during 10 min. of liquid plasma treatment at 20 W of average input power. The removal rate of the blood clots is typically up to 2 mm3 per minute and cylindrical volumes of 3 mm diameter and 14 mm long were removed. The thermal damage to contiguous tissue at the periphery of the removal volume was determined to be is >200 µm from conventional histology analysis. We determined by FTIR spectroscopy that the collagen denaturing in liquid plasma occurs primarily via Amide III bond breakage. magnified image
What is the gravity dual of the confinement/deconfinement transition in holographic QCD?
Authors: Morita T. , Mandal G. 
Published: February 2012

AbstractWe study the gravity dual of four dimensional pure Yang‐Mills theory through D4 branes, as proposed by Witten (holographic QCD). In this holographic QCD, it has been widely believed that the confinement phase in the pure Yang‐Mills theory corresponds to the AdS D4 soliton in gravity and the deconfinement phase corresponds to the black D4 brane. We inspect this conjecture carefully and show that the correspondence between the black D4 brane and the deconfinement phase is not correct. Instead, by using a slightly different set up, we find an alternative gravity solution called “localized soliton”, which would be properly related to the deconfinement phase. In this case, the confinement/deconfinement transition is realized as a Gregory‐Laflamme type transition. We find that our proposal naturally explains several known properties of QCD.
Gravitational anomaly and hydrodynamics in AdS/CFT
Authors: Landsteiner K. , Megías E. , Melgar L. , Pena‐Benitez F. 
Published: February 2012

AbstractUsing a holographic model with a pure gauge and mixed gauge‐gravitational Chern‐Simons terms in the action, we analyze the anomalous induced current of a vortex in the relativistic fluid via the chiral vortical effect, which is analogous to the anomalous current induced by a magnetic field via the chiral magnetic effect. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid characterized by a term proportional to T2. The numerical value of this term is not renormalized compared to the weak coupling result [1]. We also address on a general formalism to unify the two inequivalent implementations to the chemical potential for an anomalous symmetry presented in [2].
Generalized quark‐antiquark potential in AdS/CFT
Authors: Forini V. , Drukker N. 
Published: February 2012

AbstractIn this talk we present a family of Wilson loop operators which continuously interpolates between the 1/2 BPS line and the antiparallel lines, and can be thought of as calculating a generalization of the quark–antiquark potential for the gauge theory on S3 × R. We evaluate the first two orders of these loops perturbatively both in the gauge and string theory. We obtain analytical expressions in a systematic expansion around the 1/2 BPS configuration, and comment on possible all‐loop patterns for these Wilson loops.
Superparamagnetism in CuFeInTe3 and CuFeGaTe3 alloys
Authors: Grima‐Gallardo P. , Alvarado F. , Muñoz M. , Durán S. , Quintero M. , Nieves L. , Quintero E. , Tovar R. , Morocoima M. , Ramos M. A. 
Published: March 2012

AbstractThe temperature dependencies of DC magnetic susceptibilities, χ(T), of CuFeInTe3 and CuFeGaTe3 alloys were measured in a SQUID apparatus using the protocol of field cooling (FC) and zero FC (ZFC). The FC curves of both samples reflect a weak ferromagnetic (or ferrimagnetic) behavior with a nearly constant value of χ(T) in the measured temperature range (2–300 K) indicating that the critical temperatures (Tc) are >300 K. The ZFC curves diverges from FC, showing irreversibility temperatures (Tirr) of ∼250 K for CuFeInTe3 and >300 K for CuFeGaTe3, suggesting that we are dealing with cluster‐glass systems in a superparamagnetic state.
Simulation of AlGaN and BGaN metal‐semiconductor‐metal ultraviolet photodetectors
Authors: Hamady Sidi Ould Saad 
Published: February 2012

AbstractIn this report, we study, by means of numerical simulation, the impact of the active layer properties and device geometry on the performance of the “solar blind” UV MSM detector based on AlGaN and BGaN alloys. The parameters investigated, using the Silvaco Athena and Atlas tools, were: (i) the Schottky contact width and thickness; (ii) the ternary (AlGaN or BGaN) physical properties, including the active layer thickness, n‐type doping concentration and traps density. We implement the physical models and the ternary material properties, taken from literature or, if not available (as for the new BGaN ternary), from the interpolation between the binary materials weighted by the mole fractions. We have found that: (i) the photocurrent is highly improved by optimizing the device geometry, in particular the Schottky contact semi‐transparency (depending on the contact thickness and metal absorption spectrum) and width; (ii) the doping and traps highly impact the device spectral response, and, in particular, a compromise in the doping concentration must be reached in order to maximize the detector performances; (iii) the incorporation of a small amount of boron in the active layer improves the detector spectral response. These results give us a powerful tool in order to understand quantitatively the impact of elaboration and processing conditions on the photodetector characteristics and thus identify the key issues in technology development (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of the SiO2/Si3N4 passivation bilayer thickness on the rectifier behavior of AlGaN/GaN HEMTs on (111) silicon substrate
Authors: Mattalah M. , Soltani A. , Gerbedoen J.‐C. , Ahaitouf Az. , Defrance N. , Cordier Y. , De Jaeger J.‐C. 
Published: February 2012

AbstractThis work describes a study regarding the SiO2/Si3N4 passivation layer thickness effect on the Au/Mo/ Al0.25Ga0.75N/GaN/Si (111) rectifier contact behaviour. Two total different thicknesses of SiO2/Si3N4dielectric are deposited on AlGaN/GaN with different residual stress which modify the stress in the AlGaN barrier under the gate. The defects occuring at the dielectric/AlGaN interface are characterized using the photoluminescence technique. I‐V characteristics of both Schottky contacts show that the thicker passivation change the Schottky contact behaviour and permit to reduce significantly the density of interface traps involving a drop of the Schottky leakage current of several order of magnitude. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Atom probe tomography study of GaMnN thin films
Authors: Nicholas Robert , Diercks David , Kane Matthew 
Published: February 2012

AbstractDetermining the nanoscale atomic distribution of transition metals is essential for understanding the magnetic behavior of III‐nitride semiconductors. Atom probe tomography is a characterization technique that can provide direct physical detection of the location of atoms and thus is ideal for investigating nanoscale atomic ordering in these materials. This work presents a study of GaMnN thin films grown bymetalorganic chemical vapor deposition that are characterized utilizing the state of the art local electrode atom probe (LEAP™) to determine the atomic ordering of Mn in an effort to help understand the nanoclustering behaviour which leads to observed room‐temperature ferromagnetic behaviour in GaMnN. The distribution of Mn on the atomic scale was found to be random in nature in the bulk of the thin film where the analysis was performed with no evidence for the predisposition of Mn to form dimers, trimers or clusters. Other sources of clustering must lead to the room‐temperature ferromagnetic behaviour that has been observed in these samples, such as surface segregation of Mn during the growth process. This work proves consistent with prior magnetic analysis in that most atoms in the crystal are isolated Mn atoms which result in a paramagnetic signal. This work is a first step towards the ultimate goal of understanding the structure‐property‐growth condition relationships for the tailoring of specific MOCVD processes in nitride semiconductors. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of doping on screw threading dislocations in AlN and their role as conductive nanowires
Authors: Kioseoglou J. , Kalesaki E. , Belabbas I. , Chen J. , Nouet G. , Komninou Ph. , Karakostas Th. 
Published: February 2012

AbstractThe effect of threading dislocations on the electronic properties of AlN is investigated through density functional theory calculations on the six atom ring core of c ‐screw dislocations. Additional calculations are performed in order to elucidate the effect of doping through decoration of the dislocation cores by Indium and Oxygen atoms. Substitution of Al (N) core atoms by In (O) impurities as well as incorporation of a rhombohedral In2O3 structural unit in the core, are examined. It is revealed that multiple levels are induced in the band gap of AlN in all cases and screw dislocations are identified as conduction pathways to charge carriers. This feature is exemplified when rhombohedral In2O3 is incorporated in the cores. The presence of these dopants shall augment the conductivity along the dislocation line and new prospects arise for AlN threading dislocations since, following the “dislocation technology” scheme, the role of conductive nanowires in semiconducting thin films is appointed to doped screw dislocations (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transfer characteristic of zinc nitride based thin film transistors
Authors: Bhattacharyya S. R. , Ayouchi R. , Pinnisch M. , Schwarz R. 
Published: February 2012

AbstractPolycrystalline zinc nitride (Zn3N2) thin films were prepared on quartz and aluminum tin oxide/indium tin oxide (ATO/ITO) and SiO2‐covered crystalline silicon by reactive pulsed laser ablation (PLD) of a metallic zinc target using a pulsed Nd:YAG laser, assisted by a 13.56 MHz radio‐frequency (RF) nitrogen plasma. The microstructural, optical and electrical properties of the as‐deposited films were studied by Scanning Electron Microscopy (SEM), X‐ray diffraction (XRD), low‐temperature photoluminescence (PL), optical transmittance, and field effect transistor I‐V measurements. SEM revealed a compact and crack‐free film surface. XRD study indicated that the Zn3N2 films deposited at 673 K substrate temperature were cubic, with lattice constant a = 0.97 nm and having no preferred orientation. PL spectra taken at 4.2 K show a 7‐9 meV wide exciton‐related peak at 3.59 eV. The optical absorption coefficient, estimated from the transmission spectra using Beer's law, was utilized to determine the optical band gap of the films. The Zn3N2 showed a direct band gap of ∼3.2 eV at room temperature. Transparent field effect transistor structures with a 200 nm thick Zn3N2 film as active channel layer exhibited non‐linear I–V transfer characteristics, which is typical of devices having a large density of interface trap states (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sparse random graphs: Eigenvalues and eigenvectors
Authors: Tran Linh V. , Vu Van H. , Wang Ke 
Published: March 2012

AbstractIn this paper, we prove the semi‐circular law for the eigenvalues of regular random graph Gn,d in the case d →∞, complementing a previous result of McKay for fixed d. We also obtain a upper bound on the infinity norm of eigenvectors of Erdős–Rényi random graph G(n,p), answering a question raised by Dekel–Lee–Linial. © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 2012
Small‐Caliber Vascular Prosthesis Prototype Based on Controlled Release of Heparin from Mesochannels and Its Enhanced Biocompatibility
Authors: Zhou Yu , Li Kun , Yang Jia Yuan , Guan Chen Xi , Wang Ying , Liu Chang Jian , Zhu Jian Hua 
Published: February 2012

AbstractA novel small‐caliber vascular prosthesis prototype is proposed on the basis of a new heparin release system, that is, the controlled delivery of heparin from mesochannels. Fabrication of mesochannels on artificial biomaterials is successfully achieved through epitaxial growth of mesoporous silica nanoparticles on expanded polytetrafluoroethylene grafts, and thus heparin can be immobilized through a space limitation effect, thereby avoiding the loss of bioactivity and enabling long‐lasting release. The adsorption and release of heparin are controlled by adjusting the adsorbate–adsorbent interaction through tailoring the mesostructure. Owing to the continuous and sustained release of heparin, the performances of artificial vessels are greatly improved, thus paving a new way to prepare functional blood‐contacting biomaterials with high biocompatibility.
Plasmonic‐Coupling‐Based Sensing by the Assembly and Disassembly of Dipycolylamine‐Tagged Gold Nanoparticles Induced by Complexing with Cations and Anions
Authors: Li Dong Xiang , Zhang Jun Feng , Jang Yoon Hee , Jang Yu Jin , Kim Dong Ha , Kim Jong Seung 
Published: February 2012

AbstractA surface‐plasmon‐coupling‐mediated sensor system is developed based on Au nanoparticles tagged with a coordinative dipycolylamine and lipoyl‐anchored naphthalimide derivative (AuNP@DPA). The AuNPs with tailored ligands exhibit distinct sensing activity via sequential assembly into nanoparticle aggregates induced by metal ion complexing, and disassembly in the presence of pyrophosphate (PPi) anions, which is accompanied by a swift, reversible color change due to a surface plasmon resonance coupling effect. It is found that divalent metal ions are more effective than mono‐ or tri‐valent ions in the aggregate formation process, Mn2+‐induced aggregates are more sensitive to the capture of PPi anions than other AuNP aggregates, and the disassembly upon anion complexation exhibits a highly selective response. The AuNP@DPA‐based molecular recognition system also demonstrates a viable performance for the detection of total selective metal ions present in different types of water analytes.
Photosynthetic accumulation of carbon storage compounds under CO2 enrichment by the thermophilic cyanobacteriumThermosynechococcus elongatus
Authors: Eberly Jed O , Ely Roger L 
Published: February 2012

AbstractThe growth characteristics of Thermosynechococcus elongatus on elevated CO2 were studied in a photobioreactor. Cultures were able to grow on up to 20% CO2. The maximum productivity and CO2 fixation rates were 0.09 ± 0.01 and 0.17 ± 0.01 mg ml−1 day−1, respectively, for cultures grown on 20% CO2. Three major carbon pools—lipids, polyhydroxybutyrates (PHBs), and glycogen—were measured. These carbon stores accounted for 50% of the total biomass carbon in cultures grown on atmospheric CO2 (no supplemental CO2), but only accounted for 30% of the total biomass carbon in cultures grown on 5–20% CO2. Lipid content was approximately 20% (w/w) under all experimental conditions, while PHB content reached 14.5% (w/w) in cultures grown on atmospheric CO2 and decreased to approximately 2.0% (w/w) at 5–20% CO2. Glycogen levels did not vary significantly and remained about 1.4% (w/w) under all test conditions. The maximum amount of CO2 sequestered over the course of the nine-day chemostat experiment was 1.15 g l−1 in cultures grown on 20% CO2.
Forms of Predation: Tiger and Markhor Hunting in Colonial Governance
Authors: HUSSAIN SHAFQAT 
Published: February 2012

AbstractIn this paper I compare late nineteenth and early twentieth-century sport hunting of markhor, a mountain goat, by British civil and military officials in the mountainous northern frontier region of Kashmir State, with their hunting of tigers, particularly man-eating tigers in the hilly and plains regions of India. Using these two instances, this paper elucidates and compares two competing visions of colonial governance. The British sportsman hunted man-eating tigers in order to protect Indian society from wild nature. Hunting them was also symbolic of their welfare-oriented governance ideology. They also hunted markhor in the northern mountainous region usingbegar, or forced labour, which they justified by falling back on the wider colonial representation of the northern mountainous region as a civilization-less area, where a more coercive form of governance was needed. So, rather than protecting society from nature, as in the case of man-eating tiger hunting in the plains, what was needed in the mountains was the ability of the British to introduce civilization into unruly nature via a strong disciplinary force. I argue that colonial governance entailed not simply a struggle to civilize India and its population, but a more profound struggle for control over nature.
Preferences, perceptions, and veto players: explaining devolution negotiation outcomes in the Canadian territorial north
Authors: Alcantara Christopher 
Published: February 2012

ABSTRACTSince the early part of the 20th century, the federal government has engaged in a long and slow process of devolution in the Canadian Arctic. Although the range of powers devolved to the territorial governments has been substantial over the years, the federal government still maintains control over the single most important jurisdiction in the region, territorial lands and resources, which it controls in two of the three territories, the Northwest Territories and Nunavut. This fact is significant for territorial governments because gaining jurisdiction over their lands and resources is seen as necessary for dramatically improving the lives of residents and governments in the Canadian north. Relying on archival materials, secondary sources, and 33 elite interviews, this paper uses a rational choice framework to explain why the Yukon territorial government was able to complete a final devolution agreement relating to lands and resources in 2001 and why the governments of the Northwest Territories and Nunavut have not. It finds that the nature and distance of federal-territorial preferences, combined with government perceptions of aboriginal consent and federal perceptions of territorial capacity and maturity, explain the divergent outcomes experienced by the three territorial governments in the Canadian arctic.The following acronyms are employed: AIP: Agreement-in-Principle; DTA: Devolution Transfer Agreement; GEB: gross expenditure base; GN: Government of Nunavut; GNWT: Government of Northwest Territories; NCLA: Nunavut Land Claims Agreement; NTI: Nunavut Tunngavik Incorporated; NWT; Northwest Territories; ON: Ontario; TFF: Territorial Formula Financing; UFA: Umbrella Final Agreement; YDTA: Yukon Devolution Transfer Agreement; YTG: Yukon Territorial Government; YK: Yukon;
Goethe's “Delicate Empiricism”: Assessing its Value for Australian Ecologists
Authors: Bradley Melanie 
Published: March 2012

AbstractJohann Wolfgang von Goethe, recognised as a seminal German polymath, developed a unique approach for investigating nature, termed “delicate empiricism”. Goethe's approach uses empathy, imagination and intuition to promote a participatory engagement with the world. It goes beyond the dualistic-rationalism that defines “conventional” ecological research and can lead to novel insights. “Delicate empiricism” was applied in an ecologically-degraded agricultural landscape in the Brigalow Belt, Queensland, Australia, and its potential for increasing landscape understanding and providing a basis for land-use design was assessed. It was found that Goethe's approach led to holistic, qualitative landscape awareness, not ordinarily accessible via “conventional science”. Application of “delicate empiricism” also gave rise to a land-use design that refected the Australian-nessof the Brigalow Belt landscape, particularly the potential for recovery of native biodiversity values through retention of regrowth vegetation. Overall, the study suggested that there is merit in educating Australian ecologists about “delicate empiricism” to encourage more creative and sensitive landscape management, that is in sync with the environment.