bluuebunny/crossref_metadata_2025_split huggingface dataset:
Particle size effect on the film‐forming process of PS/PBA composite latexes
Authors: Uğur Şaziye , Sunay M. Selin , Elaissari Abdelhamid , Pekcan Önder 
Published: December 2009

AbstractIn this work, the effect of hard particle size and blend ratio on the film formation behavior of hard polystyrene (PS) and soft poly(n‐butyl acrylate) (PBA) latex blends was studied by means of steady‐state fluorescence and UV–visible techniques in conjunction with atomic force microscopy. Three different sets of latexes were synthesized: PBA latex (diameter 97 nm), pyrene (P)‐labeled large PS (LgPS; diameter 900 nm), and small PS (SmPS; diameter 320 nm). Two different series of latex blends (LgPS/PBA and SmPS/PBA) were prepared with varying blend composition at room temperature separately. Films were then annealed at elevated temperatures above glass transition (Tg) temperature of PS. Fluorescence intensity (IP) from P and photon transmission intensity (Itr) were measured after each annealing step to monitor the stages of film formation. The results showed that a significant change occurred in IP and Itr at a certain critical weight fraction (Rc) of PBA. Below Rc, two distinct film formation stages, which are named as void closure and interdiffusion, were seen. However, at PBA concentrations nearer to or above Rc, no film formation can be achieved. Comparing to the LgPS/PBA, the sintering process of SmPS/PBA particles occurred at much lower temperatures. Film formation stages for R < Rc were modeled, and related activation energies were calculated. Void closure (ΔH) and interdiffusion (ΔE) activation energies for SmPS/PBA were also found smaller in comparing with LgPS/PBA series. However, ΔH and ΔE values were not changed much with the blend composition for both series. POLYM. COMPOS., 31:1637–1652, 2010. © 2009 Society of Plastics Engineers
High‐performance liquid chromatography with diode array detection coupled to electrospray time‐of‐flight and ion‐trap tandem mass spectrometry to identify phenolic compounds from a Cistus ladanifer aqueous extract
Authors: Fernández‐Arroyo S. , Barrajón‐Catalán E. , Micol V. , Segura‐Carretero A. , Fernández‐Gutiérrez A. 
Published: December 2009

AbstractIntroduction – Cistus ladanifer is an aromatic shrub that is widespread in the Mediterranean region. The labdanum exudate is used in the fragrance industry and has been characterised. However, there is not enough information about the phenolic content of the raw plant, the aerial part of it being a very rich source of bioactive compounds.Objective – Characterisation of the bioactive compounds of the raw plant and its aerial parts.Methodology – High‐performance liquid chromatography with diode array and electrospray ionisation mass spectrometric detection was used to carry out the comprehensive characterisation of a Cistus ladanifer shrub aqueous extract. Two different MS techniques were coupled to HPLC: time‐of‐flight mass spectrometry and tandem mass spectrometry.Results – Many well‐known compounds present in Cistus ladanifer were characterised, such as flavonoids, phenolic acids, ellagitanins, hexahydroxydiphenoyl and derivatives, and other compounds.Conclusion – The method described simultaneously separated a wide range of phenolic compounds and the proposed characterisation of the major compounds of this extract was carried out. It is important to highlight that, to our knowledge, this is the first time that a Cistus ladanifer aqueous extract from the raw plant has been characterised. Copyright © 2009 John Wiley & Sons, Ltd.
Thin film solar cells incorporating microcrystalline Si1–xGex as efficient infrared absorber: an application to double junction tandem solar cells
Authors: Matsui Takuya , Jia Haijun , Kondo Michio 
Published: December 2009

AbstractWe have fabricated efficient (∼7–8%) hydrogenated microcrystalline Si1–xGex (µc‐Si1–xGex:H, x ∼ 0.1–0.17) single junction p‐i‐n solar cells with markedly higher short‐circuit current densities than for µc‐Si:H (x = 0) solar cells due to enhanced infrared absorption. By replacing the conventional µc‐Si:H with the µc‐Si1–xGex:H as infrared absorber in double junction tandem solar cells, the bottom cell thickness can be reduced by more than half while preserving the current matching with hydrogenated amorphous silicon (a‐Si:H) top cell. An initial efficiency of 11.2% is obtained for a‐Si:H/µc‐Si0.9Ge0.1:H solar cell with bottom cell thickness less than 1 µm. Copyright © 2009 John Wiley & Sons, Ltd.
Forty three per cent composite split‐spectrum concentrator solar cell efficiency
Authors: Green Martin A. , Ho‐Baillie Anita 
Published: December 2009

AbstractOne way of improving the efficiency of solar cells is to subdivide the broad solar spectrum into smaller energy ranges and to convert each range with a cell of appropriately matched bandgap. The most common approach to implementing this idea has been to use a monolithic or mechanical stack of cells arranged in order of increasing bandgap, with the highest bandgap cell uppermost. This provides automatic filtering of incident sunlight so that each cell absorbs and converts the optimal spectral range. The potential of an earlier experimental approach based on steering light in different wavelength bands to non‐stacked cells recently has been re‐explored with good results. The present work extends this previous work by putting measurements on a more rigorous basis and by improving the ‘composite’ experimental efficiency of selected cells to beyond 43%, the highest reported to date for any combination of photovoltaic devices. Copyright © 2009 John Wiley & Sons, Ltd.
Evaluation of photovoltaic modules based on sampling inspection using smoothed empirical quantiles
Authors: Steland Ansgar , Herrmann Werner 
Published: December 2009

AbstractAn important issue for end users and distributors of photovoltaic (PV) modules is the inspection of the power output specification of a shipment. The question is whether or not the modules satisfy the specifications given in the data sheet, namely the nominal power output under standard test conditions† relative to the power output tolerance. Since collecting control measurements of all modules is usually unrealistic, decisions have to be based on random samples. In many cases, one has access to flash data tables of final output power measurements (flash data) from the producer. We propose to rely on the statistical acceptance sampling approach as an objective decision framework, which takes into account both the end users and producers risk of a false decision. A practical solution to the problem is discussed which has been recently found by the authors. The solution consists of estimates of the required optimal sample size and the associated critical value where the estimation uses the information contained in the additional flash data. We propose and examine an improved solution which yields even more reliable estimated sampling plans as substantiated by a Monte Carlo study. This is achieved by employing advanced statistical estimation techniques. Copyright © 2009 John Wiley & Sons, Ltd.
Shunt removal and patching for crystalline silicon solar cells using infrared imaging and laser cutting
Authors: Zhang Lucheng , Shen Hui , Yang Zhuojian , Jin Jingsheng 
Published: December 2009

AbstractShunts in crystalline silicon solar cells can be physically removed and replaced with good cells to eliminate their influences, which is proved by the experiments in this paper. By infrared imaging and laser cutting, the shunted regions near the edges of cell A and in the middle of cell B were identified and removed with their efficiencies increased by 6·8% and 3·0%, respectively. After shunt removal, cell B was patched up with good cells and its final work current further increased from 3·71 to 4·11 A. The result implies that this work could improve the output power and current matching in a module for the repaired cell. Copyright © 2009 John Wiley & Sons, Ltd.
A new analog MPPT technique: TEODI
Authors: Femia N. , Petrone G. , Spagnuolo G. , Vitelli M. 
Published: December 2009

AbstractA new analog maximum power point tracking (MPPT) technique is presented and discussed. Its main advantages are simplicity of implementation, absence of memory and multiplication operations, and the high MPPT efficiency obtainable under both stationary and time‐varying atmospheric conditions. A numerical analysis, carried out by using the Perturb and Observe MPPT technique as a benchmark reference, confirms the validity of the proposed approach. Copyright © 2009 John Wiley & Sons, Ltd.
Surface Activation of Poly(methyl methacrylate) via Remote Atmospheric Pressure Plasma
Authors: II Eleazar Gonzalez , Barankin Michael D. , Guschl Peter C. , Hicks Robert F. 
Published: December 2009

AbstractAn atmospheric pressure oxygen and helium plasma was used to activate the surface of poly(methyl methacrylate) (PMMA). The plasma physics and chemistry was investigated by numerical modeling. It was shown that as the electron density of the plasma increased from 3 × 1010 to 1 × 1012 cm−3, the concentration of O atoms and metastable oxygen molecules (1Δg) in the afterglow increased from 6 × 1015 to 1 × 1017 cm−3. Exposing PMMA to the afterglow for times between 0 and 30 s led to a 35° ± 3° decrease in water contact angle, and a ten‐fold increase in bond strength to several adhesives. X‐ray photoelectron spectroscopy of the polymer revealed that after treatment, the surface carbon attributable to the methyl pendant groups decreased 5%, while that due to carboxyl acid groups increased 7%. The numerical modeling of the afterglow and experimental results indicate that oxygen atoms generated in the plasma oxidize the polymer chains.magnified image
The Substrate and Composition Dependence of Plasma Polymer Stability
Authors: Robinson David E. , Buttle David J. , Whittle Jason D. , Parry Kristina L. , Short Robert D. , Steele David A. 
Published: December 2009

AbstractFilm stability of functionalised plasma polymer (PP) films in aqueous environments is an issue. Whilst methods are routinely employed to enhance aqueous stability, the issue itself has not previously been systematically studied. Herein, we describe a method using gradient PP surfaces whereby aqueous stability can be explored as a function of PP composition and substratum. X‐ray photoelectron spectroscopy (XPS) is used to examine PP films on glass and Thermanox “as‐prepared” and post‐immersion (24 h) in distilled H2O. Our data indicate stability becomes an issue with increase in functionalisation, but that functionalised PPs are much more stable when deposited on polymeric Thermanox than when deposited onto glass. Substratum influence in PP films thicker than the XPS sampling depth is a surprise.magnified image
Deposition of Functional Organic Thin Films by Pulsed Plasma Polymerization: A Joint Theoretical and Experimental Study
Authors: Denis Laurent , Marsal Philippe , Olivier Yoann , Godfroid Thomas , Lazzaroni Roberto , Hecq Michel , Cornil Jérôme , Snyders Rony 
Published: December 2009

AbstractThe pulsed plasma polymerization of allylamine and cyclopropylamine is investigated to study the influence of the precursor chemical structure on the process selectivity toward the primary amine groups. Both systems are compared under similar mean powers injected in the discharges (Pmean). The results reveal an increase in the precursor fragmentation in the plasma and a decrease in the primary amine content of the film (%NH2) as Pmean increases. Nevertheless, below a critical Pmean value, different behaviors are observed depending on the precursor, cyclopropylamine being less plasma‐fragmented than allylamine. As a result, plasma polymer films (PPF) synthesized from cyclopropylamine yield the largest %NH2. These results are rationalized with the help of theoretical calculations pointing to a preferential opening of the cyclopropylamine ring structure. Cyclopropylamine activation in the plasma can thus be achieved without fragmentation reactions, leading to a more efficient incorporation of the NH2 group of the precursor in the PPF.magnified image
Climatic and geomorphic factors affecting contemporary (1950–2004) activity of retrogressive thaw slumps on the Aklavik Plateau, Richardson Mountains, NWT, Canada
Authors: Lacelle Denis , Bjornson Jean , Lauriol Bernard 
Published: December 2009

AbstractThe climatic and geomorphic factors affecting retrogressive thaw slump initiation and activity on the Aklavik Plateau (Richardson Mountains, NWT) were examined using historical air photographs over a 54‐year period (1950 to 2004). In this region, thaw slumps include a near‐vertical headwall, a floor of low gradient (2–10°) and a steeply sloping evacuation channel (15–25°) that connects the floor of the thaw slumps to Willow River located 60–150 m below. All thaw slumps on the Aklavik Plateau are located within the glacial limit of the Laurentide Ice Sheet and the majority developed on the western side of the valley on gently sloping terrain. Aerial photographic analysis showed an increase in thaw slump initiation from 0.35 new thaw slump yr−1 over the 1954–71 period to 0.68 new thaw slump yr−1 over the 1985–2004 period. This increase follows the pattern of the 10‐year running mean summer air temperature record over the 1950–2004 period. However, the total number of active mature thaw slumps on the Aklavik Plateau decreased from a maximum of 46 in 1950 to a minimum of 24 observed in 2004, which follows, to a certain extent, the 10‐year running average of rainfall. Both these trends may relate to the influence of climate on the erosional processes that are thought to initiate thaw slumps and keep them active in regions of highlands. Copyright © 2009 John Wiley & Sons, Ltd. and Her Majesty the Queen in right of Canada.
Hydrological and geomorphological significance of rock glaciers in the dry Andes, Chile (27°–33°S)
Authors: Azócar G. F. , Brenning A. 
Published: December 2009

AbstractThe latitudinal‐altitudinal distribution of rock glaciers in the dry Chilean Andes between 27° and 33°S was analysed and their hydrological and geomorphological significance evaluated. Statistical estimation techniques were used based on digital elevation models and air photo interpretation, and sediment budget models were applied to assess surface‐lowering rates. The estimated specific density of rock glaciers in the study area is 1.4 per cent, which corresponds to 147.5 km2 and a water equivalent of 2.37 km3. A comparison with glacier water equivalents derived from revised glacier inventory data shows that rock glaciers are more significant stores of frozen water than glaciers between 29° and 32°S. The latitudinal‐altitudinal distribution of rock glacier limits roughly follows the mean annual air 0°C isotherm, but in the southern part of the study area it extends into elevations where modern regional mean annual air temperatures exceed 0°C. High Andean surface‐lowering rates inferred from rock glacier sediment budget models are in the order of 0.6–0.7 mm yr−1, which is comparable to previous results from the dry Chilean Andes, but lower than in the more humid Andes further south. Copyright © 2009 John Wiley & Sons, Ltd.
Optical characterisation of BiFeO3 epitaxial thin films grown by pulsed‐laser deposition
Authors: Himcinschi Cameliu , Vrejoiu Ionela , Friedrich Marion , Ding Li , Cobet Christoph , Esser Norbert , Alexe Marin , Zahn Dietrich R. T. 
Published: December 2009

AbstractEpitaxial thin films of bismuth ferrite, BiFeO3, were deposited by pulsed laser deposition (PLD) on SrTiO3 (100), Nb‐doped SrTiO3 (100) and DyScO3 (110) substrates. Ellipsometric spectra are obtained in the energy range 0.73‐9.5 eV by combining Variable Angle Spectroscopic Ellipsometry (VASE) and vacuum ultraviolet (VUV) ellipsometry with synchrotron radiation. The optical constants of BiFeO3 films were determined by analysing the ellipsometric spectra with a model that describes the optical response of a system consisting of air, film and substrate. The shift towards higher energies of the refractive index and extinction coefficient of the film deposited onto Nb‐doped SrTiO3 as compared with that deposited onto DyScO3 was attributed to a more compressive in‐plane epitaxial strain. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
ta‐C/Si heterojunction diodes with apparently giant ideality factors
Authors: Brötzmann Marc , Vetter Ulrich , Hofsäss Hans 
Published: December 2009

AbstractA common feature of many wide band gap heterojunction diodes is an unexplained large ideality factor n > 2. In this context we investigate the diode characteristics of heterojunction diodes consisting of a crystalline semiconductor material such as Si covered with a thin semiconducting film of amorphous or disordered material. As thin amorphous film we use tetrahedral amorphous carbon (ta‐C). These heterojunctions exhibit a pronounced rectifying behavior, low saturation current and low parasitic currents. Moreover, we observe an apparently giant ideality factor reaching values of n > 75. As a consequence, the turn on voltage is around 3 – 10 V and the I‐V curves can be measured for bias up to 40 V without reaching saturation or electrical breakdown.We present a quantitative model for the unusual diode characteristics of these Metal – Amorphous Semiconductor – Semiconductor diodes (MASS‐diodes). We demonstrate that the I‐V characteristics of the heterojunctions are well described by a serial arrangement of an ideal Schottky‐diode, a Frenkel‐Poole type resistance and an Ohmic contact resistance, emulating a p‐n‐ or Schottky diode characteristic with giant ideality factor and referred to as the FPID‐model. We propose that heterojunctions exhibiting apparently large ideality factors n ≫ 2 may possess an interfacial disordered or amorphous layer with Frenkel‐Poole conduction properties. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Indium tin oxide on copper phthalocyanine – an ellipsometry study
Authors: Friedrich Marion , Kupfer Hartmut , Zahn Dietrich R. T. 
Published: December 2009

AbstractSpectroscopic ellipsometry was employed to evaluate the influence of ITO deposition on underlying copper phthalocyanine (CuPc) thin films grown on silicon with native oxide. At first the dielectric functions of ITO and copper phthalocyanine were derived from a multi‐sample analysis of single layer samples. While the CuPc films were isotropic in the substrate plane they showed a strong anisotropy in their optical response perpendicular to the film plane. Obvious higher values were observed below 1.9 eV for the real part, and over the whole spectral range (0.7 – 5 eV) for the imaginary part of the dielectric function perpendicular to the film plane. The dielectric functions were applied to model the double layer samples with ITO on top, resulting in a good match of modelled and measured ellipsometry spectra. This is a clear indication that the ITO deposition does not destroy or strongly modify the optically anisotropic CuPc layer. In a next step the CuPc dielectric function was varied to improve the fit resulting in a slight line shape change. This change might be a hint for possible phase transformation of a small part of the CuPc from α to β phase due to ITO deposition. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of the band offsets between ultrathin GaN(000) layers and sapphire (0001) by photoelectron spectroscopy
Authors: Hamsen C. , Lorenz P. , Schaefer J. A. , Krischok S. 
Published: December 2009

AbstractUltrathin layers of N‐face GaN(000) on c‐plane sapphire have been grown via plasma assisted molecular beam epitaxy (PAMBE) and investigated in‐situ via reflection of high energy electron diffraction (RHEED), Xray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Our studies of the electronic interface between substrate and adsorbate reveal a band offset about (1.7 ± 0.1) eV at the GaN‐sapphire interface and an additional band bending of the GaN layer of 0.4 eV within the first 3 nm. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure determination of Pd‐catalyst supported on S‐terminated GaAs(001) using DFT calculation
Authors: Ishii Akira , Asano Hiroki , Yokoyama Mami , Tsukamoto Shiro , Shuto Satoshi , Arisawa Mitsuhiro 
Published: December 2009

AbstractThe density functional calculation is performed to determine the structure of the reused palladium catalyst on sulphur terminated GaAs(001) surface for the Heck reaction. The DFT calculation has been done for S‐terminated GaAs(001) surface with and without As of the topmost layer. The difference the two model of the S‐terminated GaAs(001) is very small. Since, for both case, the binding energy of palladium atom is stronger due to the co‐adsorption of sulphur, the role of sulphur is to make the binding of palladium stronger. Moreover, the heights of the position of the adsorbed palladium atom for both model cases are lower than sulphur atom on the surface. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopic ellipsometry and reflection anisotropy spectroscopy of lutetium diphthalocyanine films on silicon
Authors: Seidel Falko , Fronk Michael , Himcinschi Cameliu , Chis Vasile , Zahn Dietrich R. T. 
Published: December 2009

AbstractThe main aim of this work is to investigate organic thin films by the use of Reflection Anisotropy Spectroscopy (RAS) and Spectroscopic Ellipsometry (SE) in situ during growth of the thin films on silicon substrates. The investigated material is the rare‐earth diphthalocyanine LuPc2. The LuPc2 films were deposited on hydrogen passtivated Si(111) and on oxidised Si substrates by Organic Molecular Beam Deposition (OMBD). The films on H‐Si(111) show a high anisotropic behaviour. Model calculations for in situ SE measurements revealed angles between θ = 60° and 90° for LuPc2 on H‐Si(111). Furthermore, the energy transitions found match to those determined by Density Functional Theory calculations (DFT). (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Heterointerface relief in the (311)A‐oriented GaAs‐AlAs superlattices
Authors: Gulyaev Dmitry , Zhuravlev Konstantin 
Published: December 2009

AbstractThe low‐temperature steady‐state photoluminescence (PL) and the PL kinetics of the type II (100)‐ and (311)A‐oriented GaAs/AlAs superlattices (SLs) in the electric field were studied to define the parameters of the heterointerfaces relief in the (311)A‐SLs. The electric field leads to the isotropic reduction in the PL intensity and acceleration of the PL kinetics of the (100)‐SL, whereas these effects in the (311)A‐SL are anisotropic. These electric field effects in the steady‐state PL and the PL kinetics of the (100)‐ and (311)A‐SLs are caused by the transfer and capture of the carriers at the nonradiative recombination centers. These carriers are originally localized in the wide quantum wells which appear due to the heterointerface roughness. According to the data obtained the lateral sizes of the microcavities in the [01] directions both in the direct and invert faceted heterointerfaces of the (311)A‐SL exceed 3.2 nm and the modulation of the AlAs layer width is 0.8–1.2 nm. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In situ Raman growth monitoring of indium/copper phthalocyanine interfaces
Authors: Schäfer Philipp , Himcinschi Cameliu , Chis Vasile , Zahn Dietrich R. T. 
Published: December 2009

AbstractInterface formation between indium and copper phthalocyanine (CuPc) is investigated using in situ Raman spectroscopy. CuPc and indium are deposited onto hydrogen passivated Si (111) surfaces via molecular beam deposition under ultra high vacuum (UHV) conditions. The 647.1 nm excitation wavelength of the Krypton laser fulfils resonance conditions for the CuPc molecules and provides a reasonable signal‐to‐noise ratio for thin films in the nanometer regime even for accumulation times below one minute. Indium clusters are formed at the interface and the surface enhanced Raman spectroscopy (SERS) effect is observed. A comparison of the spectra with results of density functional theory (DFT) calculations do not support a formerly proposed structure of CuPc/indium mixed layers with covalent‐like bonds [1]. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)