bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of a single dose inhaled corticosteroid on the dynamics of airway obstruction after exercise
Authors: Driessen J.M.M. , Nieland H. , van der Palen J.A.M. , van Aalderen W.M.C. , Thio B.J. , de Jongh F.H.C. 
Published: May 2011

AbstractRationaleExercise‐induced bronchoconstriction (EIB) is defined as a transient narrowing of the airways induced by exercise. Repetitive measurements of spirometric parameters, such as FEV1 and expiratory flows, and forced oscillation technique (FOT) measurements can be used to analyze the dynamics of EIB. A single high dose of fluticasone propionate (FP) protects against EIB. The aim of the study was to analyze the effect of FP on the dynamics of exercise‐induced airway narrowing as measured with FOT and spirometry.MethodsTwelve children performed an exercise challenge on 2 separate days, 4 hr after inhalation of 1 mg FP (pressurized metered dose inhaler) or a placebo. Before and after the exercise flow‐volume loops as well as the FOT (frequency range: 4–32 Hz) were measured.ResultsThe FEV1, and FEF50 fell significantly after exercise within groups; the peak fall in FEV1 after FP was significantly smaller than after placebo (respectively, 19.3 ± 14.6% and 29.2 ± 14.8%, P = 0.03, 95% CI: 0.9–18.8%). The fall in FEV1 and FEF50 peaked 3 min after exercise and showed a subsequent partial recovery. The fall in the FEV1/FVC ratio showed a later peak fall (12 min after exercise). The resistance increased while the reactance decreased significantly after exercise. FP significantly decreased the maximal increase in Rrs6 when compared to the placebo (respectively 176.5 ± 59.1% and 201.0 ± 63.8%, P = 0.05, 95% CI: 0.5–48.7%). The maximal decrease in Xrs6 was not significantly affected by FP (P = 0.06).ConclusionRepetitive spirometric and FOT measurements after exercise show a rapid narrowing and steady recovery of the patency of the conducting airways, and indicate a delayed and prolonged recovery of the smaller airways. A single high dose of inhaled FP seems to employ its effect mainly in the conducting airways. Pediatr. Pulmonol. 2011; 46:849–856. © 2011 Wiley‐Liss, Inc.
Abundance and functional roles of intrinsic disorder in allergenic proteins and allergen representative peptides
Authors: Xue Bin , Soeria‐Atmadja Daniel , Gustafsson Mats G. , Hammerling Ulf , Dunker A. Keith , Uversky Vladimir N. 
Published: May 2011

AbstractThe pathological process of allergies generally involves an initial activation of certain immune cells, tied to an ensuing inflammatory reaction on renewed contact with the allergen. In IgE‐mediated hypersensitivity, this typically occurs in response to otherwise harmless food‐ or air‐borne proteins. As some members of certain protein families carry special properties that make them allergenic, exploring protein allergens at the molecular level is instrumental to an improved understanding of the disease mechanisms, including the identification of relevant antigen features. For this purpose, we inspected a previously identified set of allergen representative peptides (ARPs) to scrutinize protein intrinsic disorder. The resulting study presented here focused on the association between these ARPs and protein intrinsic disorder. In addition, the connection between the disorder‐enriched ARPs and UniProt functional keywords was considered. Our analysis revealed that ∼ 20% of the allergen peptides are highly disordered, and that ∼ 77% of ARPs are either located within disordered regions of corresponding allergenic proteins or show more disorder/flexibility than their neighbor regions. Furthermore, among the subset of allergenic proteins, ∼ 70% of the predicted molecular recognition features (MoRFs that consist of short interactive disordered regions undergoing disorder‐to‐order transitions at interaction with binding partners) were identified as ARPs. These results suggest that intrinsic disorder and MoRFs may play functional roles in IgE‐mediated allergy. Proteins 2011; © 2011 Wiley‐Liss, Inc.
pKa predictions with a coupled finite difference Poisson–Boltzmann and Debye–Hückel method
Authors: Jim Warwicker  
Published: May 2011

AbstractModeling charge interactions is important for understanding many aspects of biological structure and function, and continuum methods such as Finite Difference Poisson–Boltzmann (FDPB) are commonly employed. Calculations of pH‐dependence have identified separate populations; surface groups that can be modeled with a simple Debye–Hückel (DH) model, and buried groups, with stronger resultant interactions that are dependent on detailed conformation. This observation led to the development of a combined FDPB and DH method for pKa prediction (termed FD/DH). This study reports application of this method to ionizable groups, including engineered buried charges, in staphylococcal nuclease. The data had been made available to interested research groups before publication of mutant structures and/or pKa values. Overall, FD/DH calculations perform as intended with low ΔpKa values for surface groups (RMSD between predicted and experimental pKa values of 0.74), and much larger ΔpKa values for the engineered internal groups, with RMSD = 1.64, where mutant structures were known and RMSD = 1.80, where they were modeled. The weaker resultant interactions of the surface groups are determined mostly by charge–charge interactions. For the buried groups, R2 for correlation between predicted and measured ΔpKa values is 0.74, despite the high RMSDs. Charge–charge interactions are much less important, with the R2 value for buried group ΔpKa values increasing to 0.80 when the term describing charge desolvation alone is used. Engineered charge burial delivers a relatively uniform, nonspecific effect, in terms of pKa. How the protein environment adapts in atomic detail to deliver this resultant effect is still an open question. Proteins 2011; © 2011 Wiley‐Liss, Inc.
Application of the Gaussian dielectric boundary in Zap to the prediction of protein pKa values
Authors: Word J. Michael , Nicholls Anthony 
Published: May 2011

AbstractThe results of two rounds of blind pKa predictions for ionizable residues in staphylococcal nuclease using OpenEye's legacy protein pKa prediction program based on the Zap Poisson–Boltzmann solver were submitted to the 2009 prediction challenge organized by the Protein pKa Cooperative and first round predictions were discussed at the corresponding June 2009 Telluride conference. To better understand these results, 21 additional sets of predictions were performed with the same program, varying the internal dielectric, reference pKa, partial charge set, and dielectric boundary. The internal dielectric (ϵp) and dielectric boundary were the two most important factors contributing to the quality of the predictions. Although the lowest overall errors were observed with a molecular dielectric boundary at ϵp = 8, predictions using a smooth Gaussian dielectric boundary performed almost as well at lower ϵp values because the Gaussian boundary implicitly accounts for a significant level of solvent penetration. Improved pKa predictions with the Gaussian boundary methodology will require better prediction and modeling of structural changes due to changes in ionization state, perhaps without resorting to the more exhaustive sampling of conformational states used by other recent continuum methods. Proteins 2011; © 2011 Wiley‐Liss, Inc.
Storage tank fire accidents
Authors: Zheng Bin , Chen Guo‐hua 
Published: May 2011

AbstractStorage tank fires often occur together with explosion causing major losses. Fifty storage tank fires occurring during the past 50 years in China are reviewed in this article. The results show that over 64% accidents occur in petrochemical plants, petroleum refineries and oil depots. The majority of fires resulted in explosions, i.e., 82% resulted in explosions. The fire disaster occurred mostly during maintenance, repair, and loading or unloading. Twenty‐seven percent of the accidents are due to human errors including operations and maintenance. This article identified the major operating, maintenance, and management problems that resulted in storage tank accidents. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2011
Towards a multi‐sensor system for the evaluation of aseptic processes employing hydrogen peroxide vapour (H2O2)
Authors: Reisert Steffen , Geissler Hanno , Flörke Rudolf , Näther Niko , Wagner Patrick , Schöning Michael J. 
Published: May 2011

AbstractThe presented work focuses on the development of a multi‐sensor system for the evaluation of aseptic processes employing hydrogen peroxide vapour. In a first step, selected commercially available gas sensors have been investigated on cross‐sensitivity towards hydrogen peroxide vapour and humidity. An MOX (TGS 816, Figaro) and a solid‐electrolyte gas sensor (SO‐A0‐250, Electrovac) (λ‐probe) have shown good characteristics in terms of sensitivity towards HPV, considering also reproducibility, long‐term drift and stability. Further, the sterilization effect of HPV has been investigated by means of the microbial reduction test. A correlation between the microbial reduction of Bacillus subtilis spores and the sensor response in hydrogen peroxide atmosphere has been established. Based on this correlation the microbial reduction may be estimated by means of the sensor output over a wide range of parameters.
A silicon‐based multi‐sensor chip for monitoring of fermentation processes
Authors: Bäcker M. , Pouyeshman S. , Schnitzler Th. , Poghossian A. , Wagner P. , Biselli M. , Schöning M. J. 
Published: May 2011

AbstractThis paper describes the design and characterization of a silicon‐based sensor chip for monitoring of fermentation processes. The sensor chip consists of three sensors using different transducer principles. A capacitive electrolyte‐insulator‐semiconductor (EIS) field‐effect structure with Ta2O5 as gate material was utilized as pH sensor. An electrolyte conductivity sensor was realized by measuring the impedance between two interdigitated electrodes (IDE). A platinum thermistor was included for temperature measurements. The EIS sensor was integrated into a bioreactor and successfully used for an inline pH measurement. The layout of the IDE has been optimized with respect to a high cell constant and a wide detectable conductivity range. The integrated platinum thermistor allowed for temperature compensation of the electrolyte conductivity measurement.
Time dependence of water‐reducing photocurrent with change of the characteristics of n‐type GaN photo‐illuminated working electrodes
Authors: Fujii Katsushi , Koike Kayo , Atsumi Mika , Goto Takenari , Itoh Takashi , Yao Takafumi 
Published: May 2011

AbstractNitride semiconductors are expected for the working electrodes of photoelectrochemical water splitting due to the chemical stability and band‐gap configuration. The p‐type nitrides are stable under photoelectrochemical conditions but the efficiency of light to hydrogen energy is low. The n‐type nitrides have relatively high energy‐conversion especially for the quantum efficiency, but the photoelectrochemical reaction is not stable because of the anodic photocorrosion. In this article, the relationships between the characteristics of n‐type GaN and the photocurrent stability are discussed. The amount of Si doping was clarified to relate to the stability. The suitable properties for stable photocurrent were different from those for high energy‐conversion efficiency at initial stage. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Next generation defect characterization in nitride HEMTs
Authors: Arehart A. R. , Malonis A. C. , Poblenz C. , Pei Y. , Speck J. S. , Mishra U. K. , Ringel S. A. 
Published: May 2011

AbstractA series of constant drain current deep level transient and optical spectroscopies (CID‐DLTS/DLOS) is described, which allows characterization of deep levels with lateral spatial resolution in fully fabricated high electron mobility transistors (HEMTs). The techniques are used to examine the role of SiNx passivation in the access region of AlGaN/GaN HEMTs, in part to verify lateral resolution capabilities. Two distinct trap spectra were observed correlating to the under‐gate and access regions of the HEMT. Traps in the access region had energy levels of of EC‐0.43, EC‐1.3, EC‐2.3, and EC‐3.7 eV. The impact of each access region trap on the drain resistance before and after passivation was measured, with the total transient drain resistance change being reduced from 0.47 Ω‐mm to 0.11 Ω‐mm as a result of their partial passivation by SiNx, resulting in improved device performance. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation and selective etch of ammonothermal GaN wafers for defect evaluation
Authors: Swider Stacy , Suscavage Michael , Wang Buguo , Lynch Candace , Bliss David 
Published: May 2011

AbstractGrowth of bulk gallium nitride by the ammonothermal method results in thick, faceted specimens presenting polar and non‐polar surfaces. In order to investigate defect density, samples need to be cut, polished, and etched. The polishing method must remove surface damage or etch tests will be inaccurate. We examined the efficacy of different polishing and etching methods on the c, a, and m planes. Polishing methods included fixed‐grit and chemo‐mechanical solutions; results were measured by atomic force microscopy (AFM). Three etchants were tried: 85% hot phosphoric acid, hot KOH‐NaOH eutectic, and photo‐enhanced chemical (PEC) etching. The eutectic etch resulted in repeatable counts on the gallium face. The non‐polar planes did not reveal etch pits (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Progress on n‐type doping of AlGaN alloys on AlN single crystal substrates for UV optoelectronic applications
Authors: Collazo Ramón , Mita Seiji , Xie Jinqiao , Rice Anthony , Tweedie James , Dalmau Rafael , Sitar Zlatko 
Published: May 2011

AbstractAs the building blocks of deep UV light emitting diode (LED) technology and high‐power electronic devices, AlGaN alloys have attracted considerable attention. In this study, AlGaN films with varying compositions doped with Si were deposited on homoepitaxial AlN layers grown on AlN single crystal substrates. The room temperature resistivity of AlGaN alloys of different compositions grown on AlN and sapphire substrates with a constant Si doping level of 6x1018 cm‐3 was compared. AlGaN films grown on AlN substrates consistently exhibited a lower n‐type resistivity than those grown on sapphire. An n‐type resistivity of 0.1 Ω cm was obtained for an AlGaN film with 80% Al content and a sheet resistance of 235 Ω/sq. for an AlGaN film with 70% Al content. The carrier activation energy as a function of Al content in AlGaN for these n‐type films was measured. For compositions below 80% Al, the activation energy was around 15 meV due to impurity potential screening. For higher Al compositions, the carrier concentration was limited by a high compensation ratio, except for AlN, which has activation energy of 250 meV. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of excess carrier dynamics in polar, semi‐polar, and non‐polar (In,Ga)N epilayers and QWs
Authors: Aleksiejūnas R. , Lubys L. , Vengris M. , Jarašiūnas K. , Wernicke T. , Hoffmann V. , Netzel C. , Knauer A. , Weyers M. , Kneissl M. 
Published: May 2011

AbstractWe studied carrier recombination and diffusion in GaN/sapphire templates, (In,Ga)N layers, and (In,Ga)N quantum well structures oriented along the polar [0001], semi‐polar [11‐22], and non‐polar [11‐20] orientations by means of light induced transient grating, differential transmission, and photoluminescence optical techniques. We show that the lifetime of excess carriers drops by orders of magnitude when changing the orientation from polar to non‐polar, both in GaN templates and (In,Ga)N layers. We attribute the shorter lifetime to carrier trapping by extended structural defects that are more abundant in non‐polar grown samples. In addition, we observe pronounced carrier localization effects in the semi‐ and non‐polar layers. We show that thick (In,Ga)N layers inherit the properties of the GaN templates. However, the thin quantum well structures show a lower carrier trapping activity. So, a better electrical quality can be assumed as compared to the thick (In,Ga)N layers. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polarity analysis of GaN nanorods by photo‐assisted Kelvin probe force microscopy
Authors: Wei Jiandong , Neumann Richard , Wang Xue , Li Shunfeng , Fündling Sönke , Merzsch Stephan , Al‐Suleiman Mohamed A. M. , Sökmen Ünsal , Wehmann Hergo‐H. , Waag Andreas 
Published: May 2011

AbstractPolarity dependence (N‐polar (000‐1) and Ga‐polar (0001)) of surface photovoltage of epitaxially grown, vertically aligned GaN nanorods has been investigated by photo‐assisted Kelvin probe force microscopy (KPFM). Commercial GaN substrates with known polarities are taken as reference samples. The polarity of GaN substrates can be well distinguished by the change in surface photovoltage upon UV illumination in air ambient. These different behaviors of Ga‐ and N‐polar surfaces are attributed to the polarity‐related surface‐bound charges and photochemical reactivity. GaN nanorods were grown on patterned SiO2/sapphire templates by metal‐organic vapor phase epitaxy (MOVPE). In order to analyze the bottom surface of the grown GaN nanorods, a technique known from high power electronics and joining techniques is applied to remove the substrate. The top and bottom surfaces of the GaN nanorods are identified to be N‐polar and Ga‐polar according to the KPFM results, respectively. Our experiments demonstrate that KPFM is a simple and suitable method capable to identify the polarity of GaN nanorods. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Waveguides for nitride based quantum cascade lasers
Authors: Stattin Martin , Berland Kristian , Hyldgaard Per , Larsson Anders , Andersson Thorvald G. 
Published: May 2011

AbstractWaveguide designs for AlGaN‐based near‐infrared quantum cascade lasers are investigated using a finite‐difference method mode solver. Because of the negligibly small refractive index difference between the AlN/GaN/AlGaN gain region and the surrounding AlGaN current injection and extraction layers, a low refractive index substrate (sapphire) and a low refractive index dielectric (SiO2) are used for vertical confinement of the optical field. A ridge waveguide with an off‐center contact metallization is used for lateral confinement. The off‐center contact allows for the propagation of a TM mode with low metal induced loss and sufficient optical confinement in the gain region. A viable waveguide design with a metal‐induced loss of 6.1 cm‐1 and a confinement factor of 0.52 is demonstrated. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of (1‐101) InGaN/GaN MQW stripe laser structure on Si substrate
Authors: Murase Tasuku , Tanikawa Tomoyuki , Honda Yoshio , Yamaguchi Masahito , Amano Hiroshi 
Published: May 2011

AbstractA smooth laser structure on (1‐101) GaN microstripes was successfully fabricated on a patterned (100) 8°‐off Si substrate. The sample has a high internal quantum efficiency (IQE) compared with blue LEDs on a sapphire substrate. The high‐density excitation PL spectrum observed from the cross section of the sample shows marked narrowing, and the integral PL intensity also shows a steep increase. These results indicate the onset of stimulated emission from an InGaN‐based multi quantum well (MQW) active layer on (1‐101) GaN / (100) Si. To the best of our knowledge, this is the first report of the observation of a stimulated emission from a (1‐101) MQW on a Si substrate. We succeeded in fabricating and verifying the high‐quality laser structure on semipolar (1‐101) GaN on a Si substrate. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of InGaN for photovoltaic devices
Authors: Boney C. , Hernandez I. , Pillai R. , Starikov D. , Bensaoula A. , Henini M. , Syperek M. , Misiewicz J. , Kudrawiec R. 
Published: May 2011

AbstractIn this work we present the growth and characterization of InxGa1–xN‐based materials and solar cells with x up to 0.39. The bandgap of the layers is determined by contactless electroreflectance, which indicates a substantial Stokes shift compared to photoluminescence measurements. Time‐resolved photo‐luminescence was used to confirm the existence of carrier localization phenomenon in the films. Fabricated p‐n devices are then studied for photo‐response under simulated AM0 spectral conditions and under wavelength‐dependent conditions to evaluate solar cell characteristics. All of the p‐n junctions exhibited photoresponse in the regions above their respective bandgaps. However, the dark and illuminated J‐V results indicate the existence of significant shunt and series resistances arising from material defects and non‐optimized device designs. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Selective MOVPE growth of InGaN/GaN MQW on microfacet GaN stripes
Authors: Tanikawa Tomoyuki , Murase Tasuku , Honda Yoshio , Yamaguchi Masahito , Amano Hiroshi 
Published: May 2011

AbstractWe demonstrated the effects of growth conditions such as growth pressure and growth temperature during the selective growth of InGaN/GaN multiple quantum wells (MQWs) on semipolar GaN microstripes on Si substrates. Grown layers exhibited the ridge growth, which indicates the thickness fluctuation, owing to the source supply from the apexes of the GaN microstructure. Ridge growth was suppressed by increasing growth pressure and decreasing growth temperature. Cathode luminescence (CL) analysis showed uniform luminescence. As a result, high pressure and low temperature are suitable for obtaining uniform heterostructures in the selective growth of InGaN/GaN MQWs on GaN microstripes. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
C‐plane bowing in free standing GaN crystals grown by HVPE on GaN‐sapphire substrates with photolithographically patterned Ti masks
Authors: Łucznik Bolesław , Sochacki Tomasz , Sarzyński Marcin , Kryśko Marcin , Dzięcielewski Igor , Grzegory Izabella , Porowski Sylwester 
Published: May 2011

AbstractIt is suggested that final bowing of {0001} planes in free standing GaN depends mostly on the nucleation mechanism at the beginning of the growth in the presented approach. Typical growth process in this study, includes formation of pyramidal islands through the openings in the mask, growth of the islands on their semi‐polar faces, the coalescence, smoothening of the layer and finally, bulk growth on the c‐plane of the crystal. The initial layer containing large fraction of material grown on semi‐polar faces is strongly n‐type (n > 1019 cm‐3) due to enhanced incorporation of oxygen. In contrast, the growth on c‐plane, after smoothening of the layer, results in much lower electron concentration (n < 1017 cm‐3) thus a corresponding lattice mismatch appears between semi‐polar and c‐plane growth regions. There are three results suggesting that this mismatch is an important source of stress leading to the observed c‐plane bowing: (i) relatively strong dependence of bowing radius on diameter and distance of openings in the mask, (ii) dramatic increase of the bowing radius (R = 10–80 m) if the crystallization front remains rough (entire crystal is strongly n‐type), (iii) agreement of the observed bowing radii (0.9–3 m) with theoretical estimations (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)