bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prediction of the glass transition temperature of semicrystalline polymer/salt complexes
Authors: Koh Joo Hwan , Park Jung Tae , Koh Jong Kwan , Kim Jong Hak 
Published: March 2009

AbstractAn explicit expression based on the configurational entropy model, the Flory‐Huggins theory and Guggenheim's form of Debye‐Hückel theory has been derived for predicting the glass transition temperatures (Tg) of binary semicrystalline polymer/salt complexes. The proposed configurational entropy (Sc) of polymer/salt systems consists of the disorientation entropy of polymer 1 (Sdiso‐1), the dissociation entropy of salt (Sdiss‐2), the mixing entropy (Smix‐12) and the specific interaction entropy (Sspe‐12). In particular, the effect of crystalline segments was accounted for by the current model. The prediction of the proposed Tg model is in good agreement with experimental data. Our results demonstrate that the small change of the Tg in semicrystalline polymer/salt complexes compared to amorphous systems is mostly attributable to the reduced configurational entropy due to the presence of crystalline segments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 793–798, 2009
Secondary molecular mobility in amorphous ethyl cellulose: Aging effects and degree of co‐operativity
Authors: Diogo Hermínio P. , Moura‐Ramos Joaquim J. 
Published: March 2009

AbstractThe secondary relaxations in amorphous ethyl cellulose are studied using thermally stimulated depolarization currents (TSDCs) in the temperature region from 165 °C (108 K) up to 145 °C (418 K). The influence of aging on the current peaks of the secondary relaxation is discussed, and it is concluded that some modes of motion of this mobility are aging independent, while others are affected by aging. A particular attention is focused on the discussion of the degree of co‐operativity of the motional modes of the secondary relaxation. The conclusion to be driven from the obtained TSDC results is that the aging‐independent motional modes, as well as those that are aging dependent, do not show any appreciable co‐operative character. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 820–829, 2009
Self‐assembled anionic micellar template for polypyrrole, polyaniline, and their random copolymer nanomaterials
Authors: Antony M. Jinish , Jayakannan M. 
Published: March 2009

AbstractWe report an anionic surfactant approach for size and shape control in polyaniline, polypyrrole, and their polyaniline‐co‐polypyrrole random copolymer nanomaterials. A renewable resource azobenzenesulfonic acid anionic surfactant was developed for template‐assisted synthesis of these classes of nanomaterials. The surfactant exists as 4.3 nm micelle in water and self‐organizes with pyrrole to produce spherical aggregates. The sizes of the spherical aggregates were controlled by water dilution and subsequent oxidation of these templates, produced polypyrrole nanospheres of 0.5 μM to 50 nm dimensions. The anionic surfactant interacts differently with aniline and forms cylindrical aggregates, which exclusively produce nanofibers of ∼180 nm in diameter with length up to 3–5 μM. The template selectivity of surfactant toward aniline and pyrrole was used to tune the nanostructure of the aniline‐pyrrole random copolymers from nanofiber‐to‐nanorod‐to‐nanospheres. Dynamic light scattering technique and electron microscopes were used to study the mechanistic aspects of the template‐assisted polymerization. The four probe conductivity of the copolymers showed a nonlinear trend and the conductivity passes through minimum at 60–80% of pyrrole in the feed. The amphiphilic dopant effectively penetrates into the crystal lattices of the polymer chain and induces high solid state ordering in the homopolymer nanomaterials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 830–846, 2009
Paralysis and a perihilar protuberance: An unusual presentation of sarcoidosis in a child
Authors: Wurzel Danielle F. , Steinfort Daniel P. , Massie John , Ryan Monique M , Irving Louis B. , Ranganathan Sarath C. 
Published: March 2009

AbstractSarcoidosis in children can present with extra‐pulmonary manifestations, making diagnosis difficult. We describe a case of sarcoidosis in a child, presenting as a Guillain–Barré‐like illness with the incidental finding of a perihilar mass. We also report the first successful use of the minimally invasive technique of Endobronchial Ultrasound‐Guided Transbronchial Needle Aspiration (EBUS‐TBNA) to delineate the cause of hilar lymphadenopathy in a child. Pediatr Pulmonol. 2009; 44:410–414. © 2009 Wiley‐Liss, Inc.
Predictors of major intervention in infants with bronchiolitis
Authors: Parker Melissa J. , Allen Upton , Stephens Derek , Lalani Amina , Schuh Suzanne 
Published: March 2009

AbstractObjectiveWe sought to identify predictors of the major medical intervention (MMI) in infants with bronchiolitis in the Emergency Department (ED) to recognize those in need of hospitalization versus the candidates for discharge.Patients and MethodsWe conducted an analysis of data from a prospective cohort study of previously healthy infants 2–23 months presenting to our ED with first episode of wheeze and respiratory distress. Infants were divided into those with at least one MMI defined as oxygen administration for saturation of <90%, intravenous (IV) fluids of 20 ml/kg, apnea management, or critical care unit (CCU) admission (MMI group) versus those without (no‐MMI group). The primary outcome was the association between the MMI versus no‐MMI groups and potential risk factors for these outcomes.ResultsOf 312 study infants, 52 experienced MMI—all received oxygen for saturation <90%, four also received IV fluids and none required apnea management or CCU care. The following four risk factors were associated with MMI: baseline accessory muscle score ≥6/9 [OR 2.44, 95% CI 1.29; 4.62], oxygen saturation ≤92% [OR 2.41, 95% CI 0.96; 6.14], respiratory rate ≥60 [OR 1.85, 95% CI 0.97; 3.54], and poor fluid intake [OR 2.65, 95% CI 1.12; 6.26]. Of the 148 infants without predictors 11 (7.4%) received MMI, 145 required either no MMI or oxygen for ≤6 hr and 130 (87.8%) stayed for ≤12 hr.ConclusionsInfants with bronchiolitis with high‐risk predictors should be hospitalized whereas those without can be considered for outpatient management due to low‐risk of MMI. Pediatr Pulmonol. 2009; 44:358–363. © 2009 Wiley‐Liss, Inc.
Preparation and Catalytic Activity of Co/CNTs Nanocomposites via Microwave Irradiation
Authors: Zhang Xiaojuan , Jiang Wei , Song Dan , Liu Yong , Geng Jingjing , Li Fengsheng 
Published: March 2009

AbstractCo nanoparticles supported on carbon nanotubes (CNTs) were prepared by microwave‐assisted heating of the hydrazine reduction in ethylene glycol (EG). The Co/CNT nanocomposites prepared by the microwave‐irradiation method (MIM‐Co/CNTs) were characterized by XRD, SEM, EDS, and BET. It was found that MIM‐Co/CNTs had compact coating, high cobalt loading, and large BET surface area. The obtained products for the thermal decomposition of ammonium perchlorate (AP) were investigated by DTA. The catalytic activity of MIM‐Co/CNTs was better than that of pure Co nanoparticles and Co/CNT nanocomposites by water‐bath method (WBM‐Co/CNTs). The addition of 5 wt.‐% MIM‐Co/CNTs decreased the high decomposition temperature of AP by 174.05 °C and increased the total DTA heat release by 0.799 kJ g−1.
The effect of growth temperature on physical properties of heavily doped ZnO:Al films
Authors: Hong Jongin , Paik Hanjong , Hwang Hosung , Lee Sunghwan , deMello Andrew J. , No Kwangsoo 
Published: March 2009

AbstractHeavily‐doped ZnO:Al films have been deposited on high temperature stable glass substrates using radio‐frequency (RF) magnetron sputtering. The effect of growth temperature on physical properties of the films has been investigated. The microstructure evolved a columnar structure into a granular one with the increase in growth temperature and then a typical honeycomb‐type microstructure representing huge grain formation indicating high densification. All Al‐doped ZnO films exhibited high optical transparency and the absorption edge shifted to the short wavelength (blue‐shift) as the growth temperature increased. The dense microstructure with a high crystallographic quality and large grains evolved at 500 °C enabled us to obtain 2.28 × 10–3 Ω cm and high visible transmittance over 90% even if the ZnO film was doped with an Al content of approximately 5.5 at%. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High quality Al‐doped ZnO thin films deposited using targets prepared by chemical coprecipitation
Authors: Cai L. , Jiang G. , Zhu C. , Wang D. 
Published: March 2009

AbstractIn order to grow high‐quality aluminum‐doped zinc oxide films (AZO), the chemical coprecipitation method was adopted to synthesize ultra‐fine AZO powder, in which Al2O3 was more easily and more uniformly doped in ZnO compared to the traditional mechanical grinding method. X‐ray diffraction results showed that Al atoms have replaced the position of Zn atoms in ZnO lattice without forming the Al2O3 phase. AZO thin films were deposited at a substrate temperature of 200 °C by using pulsed laser deposition. The resistivity of the AZO films was 1.7 × 10‐4 Ω cm and the light transmittance in the visible region exceeded 85%. The properties of these films commendably meet the requirements of solar cell devices. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Singlet oxygen inhibits nonradiative defects in porous silicon
Authors: Pikulev V. B. , Kuznetsov S. N. , Kuznetsov A. S. , Saren A. A. , Gurtov V. A. 
Published: March 2009

AbstractExperimental evidences are presented for the first time that singlet oxygen generated ex situ acts as an inhibitor of nonradiative recombination in porous silicon (PSi). This effect is observed on a pristine PSi as well as on degraded porous layers quenched by ozone adsorption. A photoluminescence (PL) enhancement produced by singlet oxygen is accompanied with only slight oxidation of a PSi. We assume that the observed effect on PL efficiency is due to gentle selective oxidation of single defects on silicon nanocrystal surface. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The hydrophobic properties of femtosecond laser fabricated spike structures and their effects on cell proliferation
Authors: Fadeeva Elena , Schlie Sabrina , Koch Jürgen , Ngezahayo Anaclet , Chichkov Boris N. 
Published: March 2009

AbstractSilicon (Si) spikes with an average tip surface of 1.4 μm2, an average depth 5.9 μm and a spike‐to‐spike distance of 4.8 μm have been produced with a commercial laser system which delivers sub‐30‐fs pulses at 800 nm and a repetition rate of 1 kHz. The fabricated spikes can be used for the generation of negative replica in soft material such as silicone elastomer. Since the Si spikes were not destroyed during the replication process, it is possible to reproduce ad libitum soft material with the same spike configuration rendering comparison possible. The analysis of the wettability of the surfaces revealed that the structuring induced an increase in hydrophobic character of Si as well as of silicone elastomer. This effect is related to the presence of air trapped in the microstructured surface. Analysis of the effect of the structuring on the proliferation activity of fibroblasts and SH‐SY5Y neuroblastoma cells showed that the spike structures and its negative replicas in silicone elastomer are able to suppress the proliferation of the fibroblasts for 48 h but did not affect the neuroblastoma cells. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐catalytic etching of silicon: from nanowires to regular mesopores
Authors: Boarino L. , Destro M. , Borini S. , Pugno N. , Chiodoni A. , Bellotti F. , Amato G. 
Published: March 2009

AbstractMetal assisted etching is a new promising technique for Silicon nanowires fabrication, but also for generating a new class of porous semiconductors with precise and controlled morphology, unavailable by electrochemical etching. The process and the morphology seem to be independent on substrate doping, but only on the crystallographic directions and metal patterning at the top surface. A preliminary investigation on some possible patterning techniques is reported, using porous silicon layers as pre‐patterning tool, porous alumina and polystyrene nanospheres. The influence of the masking procedure on the final array of nanostructures is discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis of DNA oligonucleotides in mesoporous silicon
Authors: Lawrie Jenifer L. , Xu Zhou , Rong Guoguang , Laibinis Paul E. , Weiss Sharon M. 
Published: March 2009

AbstractIn‐situ oligonucleotide synthesis through an 8‐base sequence is demonstrated within 30 nm silicon mesopores utilizing sequential phosphoramidite reactions. Stepwise attachment of each base is confirmed by monitoring the porous silicon effective refractive index via a waveguide resonance angle. A linear increase in the effective refractive index is observed after the addition of each base, and the detection of oligonucleotides containing only a single thymine is possible. It is estimated that 50% of the available internal pore surface is occupied by the 8‐base oligonucleotides, which is a substantially greater coverage than obtained by using traditional methods of direct attachment of presynthesized DNA oligonucleotides. The greater surface coverage by DNA probes will enable more effective biosensing devices. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of NaF precursors on low temperature growth of CIGS thin film solar cells on polyimide substrates
Authors: Caballero Raquel , Kaufmann Christian A. , Eisenbarth Tobias , Unold Thomas , Schorr Susan , Hesse Raik , Klenk Reiner , Schock Hans‐Werner 
Published: March 2009

AbstractThe aim of this work is to study the effect of Na on low temperature growth of CIGS solar cells on polyimide (PI) substrates. The Na is introduced via evaporation of a NaF precursor layer prior to the absorber deposition. As reported previously, the devices at nominal Tsub,max = 500 °C are characterized by a higher Voc when the Na content increases. However, lowering process temperature to nominally 450 °C together with high Na concentration produces a pronounced band gap grading through the absorber layer, as detected by energy dispersive X‐ray spectroscopy (EDX). The absorber layers and the devices were studied by grazing incidence X‐ray diffraction, external quantum efficiency and drive level capacitance profiling. A limit Tsub,max is identified as detrimental on the PV performance when high Na concentration is added, mainly due to a reduced Voc. 12.2% of efficiency (active area) is achieved reducing the Na concentration for the lower Tsub,max. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy transfer from rare‐earth element to Mn in (Ca,Sr)Ga2S4 compounds
Authors: Obonai Toshimitsu , Hidaka Chiharu , Takizawa Takeo 
Published: March 2009

AbstractFor realizing a red‐colour emission using SrGa2S4 compounds, Mn and rare‐earth‐element (REE) co‐doping is tried. Photoluminescence (PL) and photoluminescence excitation (PLE) spectra are measured using samples so prepared. As a result, enhancement of the Mn red emission is observed. Considering the 4f and 5d levels of REE in the host material, it is expected that the energy transfer from REE to Mn is caused by the weak coupling between the d levels of REE and Mn. Moreover, in the Ce co‐doping case, another process is expected as a resonant energy transfer between the 4f–5d transition of Ce3+ and a certain transition of Mn2+. To specify the Mn2+ levels related to the resonant transfer, PL spectra of a Mn only doped CaGa2S4 single crystal and an undoped one are measured at low temperatures, though we could not find emission expected to be related to the resonant transfer. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
CuI/Zn2x(CuIn)1–xS2/AgIn5S8 double heterojunction solar cells
Authors: Konovalov Igor , Makhova Liudmila , Roussak Liudmila 
Published: March 2009

AbstractFirst succesfull attempts to apply ZnS–CuInS2 mixed crystals in double heterojunction p–i–n solar cells in combination with AgIn5S8 and CuI are presented. Besides of studying the optoelectronic properties of the heterojunction structures, a special attention is paid to the problem of optimal band offsets and of the chemical stability. The influence of band offsets on the conversion efficiency was treated by simulation using SCAPS software, whereas the experimental band offsets were measured using X‐ray photoelectron spectroscopy. The trend of the open circuit voltage change vs. ZnS concentration can be explained by the observed change of the band offset at the interface with AgIn5S8. For each combination of the n‐type and p‐type materials in a p–i–n heterostructure, a certain maximum possible band gap in the i‐type material exists, still allowing the perfect band alignment. This band gap is about 1.2 eV for AgIn5S8 + CuI combination. The band gaps of all ZnS–CuInS2 materials being larger than 1.5 eV are too large to be used in optimal double heterojunction devices in this system. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A structural study on the CuGaSe2‐related copper‐poor materials CuGa3Se5 and CuGa5Se8: thin‐film vs. bulk material
Authors: Lehmann Sebastian , Marrón David Fuertes , Tovar Michael , Tomm Yvonne , Wolf Christian , Schorr Susan , Schedel‐Niedrig Thomas , Arushanov Ernest , Lux‐Steiner Martha Christina 
Published: March 2009

AbstractPolycrystalline samples of CuGaSe2‐related defect compounds (DC) have been prepared by Chemical Close‐Spaced Vapour Transport (CCSVT) (thin films) and elemental synthesis (powder) respectively. In the latter case a homogenisation step was introduced during the preparation, including mechanical intermixing and adjacent‐heat treatment after the main reaction. Following this route we assured conditions “close to” thermodynamic equilibrium. The influence of the annealing temperature on the lattice parameters a0 and c0, as well as the cation distribution, was investigated. By means of X‐ray and neutron diffraction analysis the structural properties of the Cu–Ga–Se based DCs have been determined and a new structural model has been derived. Finally the structural parameters of CCSVT‐grown thin‐film material were correlated with findings for bulk material samples which were intentionally prepared off‐equilibrium. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigations of interdiffusion in InGaAsP multiple‐quantum‐well structures by photoreflectance
Authors: Lin D. Y. , Lin W. C. , Wu F. L. , Wu J. S. , Pan Y. T. , Lee S. L. , Huang Y. S. 
Published: March 2009

AbstractWe present the investigations of interdiffusion in InGaAsP multiple‐quantum‐well (MQW) structures using photoreflectance (PR) and photoluminescence (PL) measurements. It is found that the degree of compositional intermixing induced by the processes of ion implantation and rapid thermal annealing in MQW structures can be obtained through the energy shift of the 11H excitonic transition. Besides, the strain relaxation resulting from intermixing is studied through the high order excitonic transitions observed in PR spectra. It is found that the splitting energy between the 11H and 11L transitions decreases as a result of increasing the degree of intermixing. Based on the theoretical calculation considering the strain effect and the different diffusion ratios between the group‐III and group‐V atoms, the data analysis have been done. It is pointed out that the diffusion coefficients and the ratio of diffusion rates between the group‐V and group‐III atoms has been enhanced by the P+ ion implantation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the stability of fluorine ions in AlGaN/GaN heterostructures: a molecular dynamics simulation study
Authors: Yuan Li , Wang Maojun , Chen Kevin J. 
Published: March 2009

AbstractFluorine ions can be effectively incorporated into AlGaN/GaN high electron mobility transistor (HEMT) structures, enabling the modulation of local potential and carrier density. The physical mechanism of fluorine incorporation in AlGaN/GaN heterojunctions is of fundamental importance to the stability of fluorine ions in AlGaN/GaN HEMTs. In this work, the molecular dynamic (MD) simulation method is used to calculate the potential energies of interstitial and substitutional fluorine atoms in AlGaN/GaN material system. Ziegler‐Biersack‐Littmark (ZBL), Lindhard‐Sorensen (L‐S) and Coulomb potential functions are applied in the MD simulation. The geometric lattice structures, spontaneous and piezoelectric polarizations, and temperature dependence are also included in the simulation. The activation energies associated with interstitial‐substitutional and interstitial‐interstitial diffusions are obtained. It is revealed that the fluorine ions are most likely located at the substitutional group‐III cation sites S(III) and the diffusion of fluorine ions should be dominated by S(III)‐interstitial process which exhibits an activation energy of 1.1 eV in Al0.25Ga0.75N and 1.4 eV in GaN in the presence of group‐III vacancies. It is expected that the removal of group‐III vacancies can significantly suppress the fluorine diffusion, which in turn, leads to excellent fluorine stability in III‐nitride materials. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Activation energy of Mg in Al0.25Ga0.75N and Al0.5Ga0.5N
Authors: Nagamatsu Kentaro , Takeda Kenichiro , Iwaya Motoaki , Kamiyama Satoshi , Amano Hiroshi , Akasaki Isamu 
Published: March 2009

AbstractThe Mg concentration dependence of the acceptor activation energy in Al0.25Ga0.75N and Al0.5Ga0.5N was investigated. Temperature‐dependent Hall effect measurements show that effective acceptor activation energy changes with a negative 1/3 power of Mg concentration, which means that the activation ratio increases with increasing Mg concentration. Similar to the case of GaN, however, overdoping of Mg causes serious compensation and a steep decrease of the hole concentration. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MBE growth of GaN and AlN using ammonia cluster ion beam – Dependence on cluster energy and growth temperature
Authors: Saito Hiroshi , Nakagawa Shun‐ichiro , Ohishi Masakazu , Imai Kazuaki 
Published: March 2009

AbstractCluster ion beam (CIB) using ammonia as a source gas is applied to molecular beam epitaxial growth of GaN and AlN. Absolute values of the flux density of Ga; F (Ga), that of Al; F (Al) and that of N; F (N), and the ratio; R =F (Ga)/F (N) are determined for quantitative discussion. In the case of GaN, the growth rate increases linearly with F (Ga) until certain value of F (Ga)=Fc, but in turn decrease for F (Ga)>Fc. The R corresponding to Fc occurs at Rc=0.14, independent of the CIB energy at a fixed growth temperature, but moves to higher R with the rise of growth temperature. The FWHM (Δω) of (0002) rocking curve of XRD having values of 2000∼4000 arcsec at smaller F (Ga) or R, decreases to below 200 arcsec with increasing F (Ga) or R. The growth rate for F (Ga)<Fc is limited by F (Ga), suggesting that the stoichiometric condition is attained at Fc or Rc. The decrease of the growth rate accompanied by narrowing of Δω (0002) for F (Ga)>Fc is related to two different kind of growth mechanisms taking place simultaneously, probably caused by the presence of excess Ga atoms on the surface. In the case of AlN, Δω (0002) shows a close relationship with the (0002) intensity in 2θ‐ω scan and has value of 200∼300 arcsec for samples with stronger (0002) intensity. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)