bluuebunny/crossref_metadata_2025_split huggingface dataset:
Titanium complexes of dialkanolamine ligands as initiators for living ring‐opening polymerization of ε‐caprolactone
Authors: Piskun Yulia A. , Vasilenko Irina V. , Kostjuk Sergei V. , Zaitsev Kirill V. , Zaitseva Galina S. , Karlov Sergei S. 
Published: January 2010

AbstractThe titanium complexes with one (1a, 1b, 1c) and two (2a, 2b) dialkanolamine ligands were used as initiators in the ring‐opening polymerization (ROP) of ε‐caprolactone. Titanocanes 1a and 1b initiated living ROP of ε‐caprolactone affording polymers whose number‐average molecular weights (Mn) increased in direct proportion to monomer conversion (Mn ≤ 30,000 g mol−1) in agreement with calculated values, and were inversely proportional to initiator concentration, while the molecular weight distribution stayed narrow throughout the polymerization (Mw/Mn ≤ 1.2 up to 80% monomer conversion). 1H‐NMR and MALDI‐TOF‐MS studies of the obtained poly(ε‐caprolactone)s revealed the presence of an isopropoxy group originated from the initiator at the polymer termini, indicating that the polymerization takes place exclusively at the Ti–OiPr bond of the catalyst. The higher molecular weight polymers (Mn ≤ 70,000 g mol−1) with reasonable MWD (Mw/Mn ≤ 1.6) were synthesized by living ROP of ε‐caprolactone using spirobititanocanes (2a, 2b) and titanocane 1c as initiators. The latter catalysts, according MALDI‐TOF‐MS data, afford poly(ε‐caprolactone)s with almost equal content of α,ω‐dihydroxyl‐ and α‐hydroxyl‐ω(carboxylic acid)‐terminated chains arising due to monomer insertion into “Ti–O” bond of dialkanolamine ligand and from initiation via traces of water, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1230–1240, 2010
Kinetics of degradation of Lycium barbarum polysaccharide by ultrasonication
Authors: Zhu Xiaohe , Zhang Honglei , Yan Hong , Yi Jianping , Zhong Rugang 
Published: January 2010

AbstractLycium barbarum polysaccharide (LBP) was subjected to ultrasonic degradation under the controlled conditions, such as, temperature, irradiation time, initial pH value, and concentration of solution. The ultrasonic degradation of LBP was demonstrated by the changes of intrinsic viscosity. Viscometry was used to study the degradation behavior and a kinetic model was developed to estimate the degradation rate. The results showed that the degradation rate was reduced with the increase of solution concentration and pH, and increased with increase of temperature. The relationship between the number average molar mass (Mn) and intrinsic viscosities as interpreted using the Mark‐Houwink equation suggested that LBP adopted a flexible coil conformation in aqueous solution. The activation energy of ultrasonic degradation of LBP is 26.5 kJ/mol, which indicates that the ultrasonic degradation is a convenient, time saving, and cost‐efficient method for obtaining a desired molecular weight. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 509–513, 2010
Effect of crosslinking on the secondary relaxation in polyvinylethylene
Authors: Casalini R. , Roland C. M. 
Published: January 2010

AbstractThe effect of network formation on the secondary (Johari–Goldstein) β‐relaxation was investigated for polyvinylethylene (PVE). Crosslinking affects the segmental (α‐) process in the usual fashion, the networks exhibiting slower and more temperature‐sensitive dynamics. However, the effect on the β‐process is the opposite. The secondary relaxation becomes faster and the activation energy slightly decreases with crosslinking. The strength of the intermolecular cooperativity governing the behavior of the α‐process was assessed using the coupling model, with consistent results obtained from analysis of both the timescale separating the α‐ and β‐relaxations and the activation energy for the latter. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 582–587, 2010
Aggregation behavior of polystyrene‐b‐poly(ethylene/butylene)‐b‐polystyrene triblock copolymer in N‐methylpyrrolidone
Authors: Ogata Yoichi , Mogi Takeshi , Makita Yutaka 
Published: January 2010

AbstractSolution property of hydrogenated polystyrene‐b‐poly(ethylene/butylene)‐b‐polystyrene triblock copolymer (SEBS copolymer) was studied by using static light scattering and dynamic light scattering for cyclohexane and N‐methylpyrrolidone (NMP) solutions. From the values of dimensionless parameters ρ, defined as the ratio of radius of gyration 〈S2〉1/2 to hydrodynamic radius RH, and solubility parameters, SEBS copolymer proved to exist as single chain close to random coil in nonpolar cyclohexane, whereas aggregate into the core‐shell micelle consisting of poly(ethylene/butylene) (PEB) core surrounded by PS shell in polar NMP. The core‐shell micelle formed in NMP is composed of 65 polymer chains, having three times larger average chain density (d = 0.12 g cm−3) than a single polymer chain (d = 0.04 g cm−3) in cyclohexane. The comparison with the aggregation behaviors in other solvents demonstrated that the aggregate compactness of the copolymer depended largely on solvent polarity, resulting in formation of the highly dense PEB core (Rc = 4.5 nm) and the thick PS shell (ΔR = 22.9 nm) in high‐polar NMP. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 588–594, 2010
High hydrogen dilution and low substrate temperature cause columnar growth of hydrogenated amorphous silicon
Authors: Bronsveld Paula C. P. , Mates Tomas , Fejfar Antonin , Kočka Jan , Rath Jatindra K. , Schropp Ruud E. I. 
Published: January 2010

AbstractColumnar growth was observed in the amorphous part of mixed phase layers deposited at very low substrate temperatures. The width of the columns and the layer thickness at which they are first distinguishable in a cross‐sectional transmission electron microscope (X‐TEM) image, about 120 nm, is similar for the substrate temperature range of 40–100 °C, but the columns are less well developed when either the substrate temperature is increased or the dilution ratio is lowered. This growth behaviour and the incubation layer are attributed to hydrogen‐induced surface diffusion of growth precursors resulting in an amorphous–amorphous roughness transition.
High deposition rate nanocrystalline silicon with enhanced homogeneity
Authors: Verkerk Arjan , Rath Jatindra K. , Schropp Ruud 
Published: January 2010

AbstractHigh rate growth of hydrogenated nanocrystalline silicon (nc‐Si:H) brings additional challenges for the homogeneity in the growth direction, since the start‐up effects affect a larger portion of the film, and the very high degree of depletion increases the influence of back diffusion from the inactive region into the plasma zone. It was calculated that back diffusion plays a role in the regime for high deposition rate (4.5 nm/s) via the residence time for particles in the plasma and the corresponding diffusion length for silane from outside the plasma. The stabilization time for back diffusion was derived and found to be on the order of tens of seconds. Experiment showed that the incubation layer for nc‐Si:H is very thick in films deposited at a high rate compared to films deposited in a regime of lower deposition rate. The use of a hydrogen plasma start greatly reduced this incubation layer. Further control of the crystalline fraction could be achieved via slight reduction of the degree of depletion via the silane flow.
Comparison of metal Schottky contacts on n‐Ge (100) at different annealing temperatures
Authors: Chawanda A. , Nyamhere C. , Auret F. D , Mtangi W. , Diale M. , Nel J. M. 
Published: January 2010

AbstractSiOC films made by the inductively coupled plasma chemical vapor deposition were researched the relationship between the dielectric constant and the chemical shift. SiOC film had the main Si‐O‐C bond with the molecule vibration mode in the range of 930∼1230 cm‐1 which consists of C‐O and Si‐O bonds related to the cross link formation according to the dissociation and recombination. The C‐O bond originated from the elongation effect by the neighboring highly electronegative oxygen atoms at terminal C‐H bond in Si‐CH3 of 1270 cm‐1. However, the Si‐O bond was formed from the second ionic sites recombined after the dissociation of Si‐CH3 of 1270 cm‐1. Increment of Si‐O bond in the Si‐O‐C main bond contributed to increase the hardness and decrease the roughness because of the decreasing of the carbon content witch is related to the space effect. The dielectric constant of SiOC film was decreased by lowering the polarization which consists of the ionic and electronic polarity. Increment of Si‐O bond in a right shoulder at the main bond was interpreted by the red shift observed in FTIR spectra. Moreover, the increment of Si‐O bond and decrement of carbon content induced to decrease the ionic polarity and then decreased the dielectric constant (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interface properties and junction behavior of Pd contact on ZnO thin film grown by vacuum deposition technique
Authors: Ali Ghusoon M. , Dwivedi A. D. D. , Singh S. , Chakrabarti P. 
Published: January 2010

AbstractIn this paper we explain the results of our experimental investigation on interface properties and junction behavior of Pd contact on ZnO thin film based Schottky diode. We used a conventional vacuum evaporation deposition unit for sequential deposition of ZnO film and metallic layer. For the first time a high quality Pd/ZnO Schottky diode is fabricated successfully in our laboratory by vacuum evaporation method. The I‐V and C‐V characteristics of the devices were studied by using microprobe arrangement. The parameter such as ideality factor, leakage current, resistance‐area‐product, carrier concentration and barrier height were extracted from the measured data. The surface morphological and the structural properties of thin film were studied by atomic force microscope. The optical band gap of thin film was determined using UV‐visible spectrophotometer. The device fabricated by a simple technique exhibited excellent stability for use as an electronic or optoelectronic component. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Designing the Si(100) conversion into SiC(100) by Ge
Authors: Nader Richard , Niebelschütz Florentina , Kulikov Dmitri V. , Kharlamov Vladimir V. , Trushin Yurii V. , Masri Pierre , Pezoldt Jörg 
Published: January 2010

AbstractThe deposition of Germanium (Ge) prior to the conversion of Si(100) into 3C‐SiC(100) results in changes of the structure and surface morphology of the formed silicon carbide layer. First of all it reduces the thickness of the 3C‐SiC layer grown during the conversion process and therefore the probability of voids formation. Secondly, it increases the nucleation density of the formed 3C‐SiC nuclei and therefore, decreases the grain size at Ge coverages below two monolayers. These affect the roughness of the SiC surface positively by modifying the width of the SiC‐Si interface. If the Ge coverages exceed two monolayers the structural and morphological properties begin to degrade. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ab initiog ‐tensor calculation for paramagnetic surface states: hydrogen adsorption at Si surfaces
Authors: Gerstmann U. , Rohrmüller M. , Mauri F. , Schmidt W.G. 
Published: January 2010

AbstractAb initio calculations of the electronic g ‐tensor of paramagnetic states at surfaces are presented taking the adsorption of hydrogen atoms at silicon surfaces as an example. We show that for silicon surfaces with different hydrogen coverages, the g ‐tensor is by far more characteristic than the hyperfine splitting of the Si dangling bonds or the adsorbed H atoms.This holds also in the case of powder spectra (e.g. amorphous or microcrystalline material) where only the angular average of the spectra is available from experiments. Hence, the ab initio calculation of the g ‐tensor should be in general a basic key to a better understanding of the microscopic structure of paramagnetic surfaces or interfaces (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and optical properties of CdS nanocrystals grown in water‐soluble diblock copolymer
Authors: Celalettin Baykul M. , Rüzgar Hilal , Arman Emine , Baş Yasemin , Bütün Vural 
Published: January 2010

AbstractMethoxy‐capped poly(ethylene glycol) (PEG) was used to prepare ATRP initiator (PEGBr). PEGBr was copolymerised with t ‐butyl methacrylate (tBMA) by using atom transfer radical polymerization (ATRP) chemistry. tBMA residues were converted to methacrylic acid (MAA) by acidic hydrolysis under mild conditions to give well‐defined PEG–b ‐PMAA diblock copolymers. Near‐monodisperse micellization was observed by the addition of CdCl2 (1.0 wt%) into PEG–b ‐PMAA diblock copolymer solution at pH 11.0 due to complexation of MAA‐ with Cd+2 ions. After addition of thioacetamide into the micellar solution, the Cd+2 cations in the resulting micelles were converted to CdS to obtain CdS nanocrystals in the micelles.The band gap of CdS nanocrystals was obtained from the absorbance measurements in the visible range and found to be 2.4 eV. Electrical resistivity of CdS nanocrystals was found to be 0.21 Ωcm. The thickness of the CdS thin films on glass substrate was found to be 131.14 nm. XRD pattern of CdS nanocrystals has shown that (111), (110), (021), and (220) diffractions are related to the cubic CdS nanocrystals. Preferred crystallographic orientation of the CdS nanocrystals is (110). TEM results have shown that grain sizes of CdS thin films vary between 64 and 133 nm (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of ZnS:Mn nanocrystals
Authors: Ahmed F. , En Naciri A. , Grob J. J. 
Published: January 2010

AbstractThe optical properties of Mn‐doped zinc sulfide (ZnS) nanocrystals embedded in SiO2 matrix are studied by spectroscopic ellipsometry (SE). The crystals are obtained by sequential multi‐energy ion implantation of Zn, S, and Mn into a silica layer grown on Si(111) followed by a subsequent annealing for 30 min at 900 °C. The formation of the nanocrystals is evidenced by transmission electron microscopy. The application of a critical‐point based model for the analysis of the SE data yields die dielectric function (DF) between 0.6 and 6.5 eV. A pronounced shift of the absorption edge towards higher energies is detected for the nanocrystals In comparison to bulk ZnS (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and optical properties of the Sb‐stabilized GaSb(001) surface
Authors: Hogan Conor , Magri Rita , Del Sole Rodolfo 
Published: January 2010

AbstractWe suggest a model for the c(2 x 6) phase of the Sbstabilized GaSb(001) surface, whereby Sb atoms in the second layer are partially substituted by Ga. This ‘doping’ effect enables the surface to fulfil the electron counting rule whilst maintaining a reconstruction based on long dimer chains.Total energy calculations verify that the suggested reconstruction is relatively stable, and calculations of the reflectance anisotropy spectra confirm that it comprises a major component of the largely disordered surface (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Voigt effect measurement on PLD grown NiO thin films
Authors: Scarlat Camelia , Mok Kah Ming , Zhou Shengqiang , Vinnichenko Mykola , Lorenz Michael , Grundmann Marius , Helm Manfred , Schubert Mathias , Schmidt Heidemarie 
Published: January 2010

AbstractNiO has great potential applications in spin valves, magnetooptical sensors, optical fibers, solar thermal absorbers, and in nonvolatile resistive random access memory devices. In our study NiMnO and NiMnLiO films have been grown on double‐side polished r‐plane sapphire substrates by pulsed laser deposition (PLD). We measured the complex Voigt angle using the polarized light from a HeCd laser, a Glan Taylor polarizer, a Hinds PEM‐100 [1] and two Lock‐Ins. The Voigt effect is a second order magnetooptic effect [2]. The polarization state of light after transmission through a sample consisting of ca. 1 μm thick, weak ferromagnetic NiO thin on purely diamagnetic r‐plane sapphire substrates has been modelled using the 4×4 matrix formalism [3] in dependence of an external magnetic field applied in‐plane, i.e. in Voigt configuration. The modelling results revealed that for the diamagnetic sapphire substrate the Voigt angle depends parabolically on the external magnetic field and that the weak ferromagnetic NiO thin films change the parabolic dependence of the Voigt angle in the range of ±0.1 T to a flat‐top shape in agreement with the experimentally determined Voigt angle (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Domain boundaries of the Si(111)‐Ge5×5 reconstruction
Authors: Mark A. G. , McLean A. B. 
Published: January 2010

AbstractThe boundaries that form between domains of the 5×5 reconstruction of Si(111)‐Ge are examined. A notation for indexing the boundaries is developed, and their symmetry properties are discussed. A preparation procedure that enhances the density of such boundaries while en‐couraging their uniform growth is described. The notation is illustrated using a selection of observed examples (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Beaver assisted river valley formation
Authors: Westbrook C. J. , Cooper D. J. , Baker B. W. 
Published: January 2010

AbstractWe examined how beaver dams affect key ecosystem processes, including pattern and process of sediment deposition, the composition and spatial pattern of vegetation, and nutrient loading and processing. We provide new evidence for the formation of heterogeneous beaver meadows on riverine system floodplains and terraces where dynamic flows are capable of breaching in‐channel beaver dams. Our data show a 1.7‐m high beaver dam triggered overbank flooding that drowned vegetation in areas deeply flooded, deposited nutrient‐rich sediment in a spatially heterogeneous pattern on the floodplain and terrace, and scoured soils in other areas. The site quickly de‐watered following the dam breach by high stream flows, protecting the deposited sediment from future re‐mobilization by overbank floods. Bare sediment either exposed by scouring or deposited by the beaver flood was quickly colonized by a spatially heterogeneous plant community, forming a beaver meadow. Many willow and some aspen seedlings established in the more heavily disturbed areas, suggesting the site may succeed to a willow carr plant community suitable for future beaver re‐occupation. We expand existing theory beyond the beaver pond to include terraces within valleys. This more fully explains how beavers can help drive the formation of alluvial valleys and their complex vegetation patterns as was first postulated by Ruedemann and Schoonmaker in 1938. Copyright © 2010 John Wiley & Sons, Ltd.
Online calculators of ecological footprint: do they promote or dissuade sustainable behaviour?
Authors: Franz Jennifer , Papyrakis Elissaios 
Published: January 2010

AbstractEcological footprint (EF) indices estimate the impact of an individual's lifestyle on the planet by converting levels of consumption into the amount of land needed to sustain production levels and lifestyle choices. Several popular organizations (e.g. WWF, Global Footprint Network) now offer personalized EF calculators to help inform consumers of the impacts of their personal consumption habits. In this paper, we evaluate the most popular online EF calculators and find that, even when the most environmentally friendly options are adopted, for the majority of available indices, one still exceeds the planet's biocapacity levels. The absence of options to fully offset one's environmental impacts implicitly suggests that there is no truly sustainable level of consumption at current population levels, even under the most prudent consumer choices. Although all online EF calculators claim to be a tool for education to promote sustainable behaviour, their calculations suggest, to the contrary, that as consumers we may postpone but not necessarily prevent environmental catastrophes. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment.
Attacks on a lightweight cipher based on a multiple recursive generator
Authors: Xiao Lu , Rose Gregory G. 
Published: January 2010

AbstractAt IEEE GLOBECOM 2008, a lightweight cipher based on a Multiple Recursive Generator (MRG) was proposed for use in resource limited environment such as sensor nodes and RFID tags. This paper proposes two efficient attacks on this MRG cipher. A distinguishing attack is firstly introduced to identify the use of an MRG cipher that has a modulus suggested by its designers. It requires 218 words of ciphertext and the most significant bit of each corresponding plaintext word. Then an efficient known plaintext attack is proposed to construct the cipher's current state and generate subkeys used for all subsequent encryption. The known plaintext attack, when targeted at the MRG ciphers optimized for efficiency, only requires 2k words of known plaintext and trivial computation where k is the MRG order. Even the ciphers based on complicated and inefficient MRGs can be attacked with low complexity, e.g. in the magnitude of 212 words of known plaintext for all MRG ciphers with order 47, regardless of which MRG modulus is used. These two attacks indicate that the examined MRG cipher structure is seriously flawed. Copyright © 2010 John Wiley & Sons, Ltd.
Corrosion fatigue on 2024T3 and 6056T4 aluminum alloys
Authors: Scala A. , Squillace A. , Monetta T. , Mitton D. B. , Larson D. , Bellucci F. 
Published: January 2010

AbstractFatigue corrosion phenomenon is a form of degradation that is because of the combined occurrence of a mechanical cyclical stress and a corrosive environment. Fatigue corrosion can be an issue in commercial and military aircraft, and has the potential to affect the structural integrity and the useful life of an aerostructure. Although the distinct consequences of both fatigue and corrosion have been extensively documented for aluminum alloys, their synergistic action is not completely understood and continues to be an area of considerable scientific and industrial interest. In this paper, a novel approach is proposed and applied for monitoring the electrochemical behavior of different types of aluminum alloy samples while they are subjected to fatigue loading. Cyclic load experiments were conducted on bare 2024T3 and 6056T4 aluminum alloy samples in the presence of an aggressive aerated solution of 3.5% NaCl over a range of frequencies. The R‐ratio was 0. Two different aluminum alloys have been tested in both high‐ and low‐cycle fatigue. In the former case, the maximum stress experienced by the specimen is lower than the material yield strength, which means that the average expected number of cycles to failure is high; in the latter case, the maximum stress experienced by the specimen during the test is higher than the material yield strength, which means that the average expected number of cycles to failure is low. The open circuit potential(OCP) was monitored versus time during the tests described above. The observed OCP variations are interpreted as the occurrence of corrosion during crack initiation and propagation at the air formed oxide/solution interface film. As expected, there is a more pronounced influence of corrosion at lower fatigue frequencies. Crack propagation allows bulk material to be progressively more exposed to the aggressive environment, which stimulates accelerated crack propagation, resulting in a lower fatigue resistance. Copyright © 2010 John Wiley & Sons, Ltd.