bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three‐dimensionally structured silicon as a substrate for the MOVPE growth of GaN nanoLEDs
Authors: Fündling Sönke , Li Shunfeng , Sökmen Ünsal , Merzsch Stephan , Hinze Peter , Weimann Thomas , Jahn Uwe , Trampert Achim , Riechert Henning , Peiner Erwin , Wehmann Hergo‐Heinrich , Waag Andreas 
Published: March 2009

AbstractThree‐dimensionally patterned Si(111) substrates are used to grow GaN based heterostructures by metalorganic vapour phase epitaxy, with the goal of fabricating well controlled, defect reduced GaN‐based nanoLEDs. In contrast to other approaches to achieve GaN nanorods, we employed silicon substrates with deep etched nanopillars to control the GaN nanorods growth by varying the size and distance of the Si pillars. The small footprint of GaN nanorods grown on Si pillars minimise the influence of the lattice mismatched substrate and improve the material quality. For the Si pillars an inductively coupled plasma dry‐etching process at cryogenic temperature has been developed. An InGaN/GaN multi quantum well (MQW) structure has been incorporated into the GaN nanorods. We found GaN nanostructures grown on top of the silicon pillars with a pyramidal shape. This shape results from a competitive growth on different facets as well as from surface diffusion of the growth species. Spatially resolved optical properties of the structures are analysed by cathodoluminescence. Strongly spatial‐dependent MQW emission spectra indicate the growth rate differences on top of the rods. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nitride‐based quantum structures and devices on modified GaN substrates
Authors: Perlin Piotr , Franssen Gijs , Szeszko Justyna , Czernecki R. , Targowski Grzegorz , Kryśko Marcin , Grzanka Szymon , Nowak Grzegorz , Litwin‐Staszewska Elżbieta , Piotrzkowski Ryszard , Leszczyński Mike , Łucznik Bolek , Grzegory Izabella , Jakieła Rafał , Albrecht Martin , Suski Tadek 
Published: March 2009

AbstractWe have studied the properties of InGaN layers and quantum wells grown on gallium nitride substrates with intentional surface misorientation with respect to its crystalline c‐axis. Misorientation varied in the range from 0 up to 2 degree. The indium content was changed by using the different growth temperature (between 750 °C and 820 °C) during metalorganic vapor phase epitaxy. With increasing misorientation angle the average indium content decreased significantly. This effect was accompanied by the strong increase of the emission line bandwidth suggesting more pronounced indium segregation. The results of cathodoluminescence measurements show that these effects correspond to different number of atomic steps/terraces existing on the surface of gallium nitride substrate. Very interesting result is also demonstrated concerning p‐type GaN layers. With increasing misorientation, the free hole density drastically increases above 1018 cm–3. This improvement in p‐type doping is not related to the increased Mg concentration but to the reduction in the compensating donor density. Using this advantage we demonstrate nitride light emitters with improved electrical properties. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and photoluminescence studies of porous silicon formed in ferric ion containing stain etchants
Authors: Dudley Margaret E. , Kolasinski Kurt W. 
Published: March 2009

AbstractStain etching of silicon in aqueous solutions composed of FeCl3 + HF + concentrated (HClO4 or H2SO4) leads to highly luminescent porous Si with a unique dual layer structure. The upper layer (∼3 μm thick) exhibits bluer luminescence (peaked at 560–590 nm) and a porosity in excess of 84%. The lower layer exhibits redder luminescence (peaked at 630–645 nm) and a lower porosity. Both layers are crystalline and are composed predominantly of uniform micropores. Because of the substantially higher porosity of the upper layer, this layer is highly susceptible to cracking and exfoliation. Critical point drying greatly reduces cracking and exfoliation but does not eliminate cracking completely. Brushing easily removes the upper layer while leaving the lower layer intact and the removed material remains photoluminescent. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of endothelial cells on pillar‐covered silicon
Authors: Zawislak Jennifer D. , Kolasinski Kurt W. , Helmke Brian P. 
Published: March 2009

AbstractBovine aortic endothelial cells were grown on nanostructured substrates consisting of pillars with height 10 μm, pitch 6 μm, and tip diameter 0.15 μm. Cells cultured on a pillar‐covered substrate were more successful than those cultured on flat silicon wafers; however, they developed more slowly than cells cultured on glass coverslips. Specifically, focal contact maturation and matrix fibrillogenesis were inhibited. In subconfluent layers, pillars are found to penetrate deeply into both the cell cytoplasm and nucleus, suggesting that cells relaxed mechanically around the 3D topography. In confluent monolayers, actin stress fiber and VE‐cadherin distributions were indistinguishable from those in confluent monolayers on coverslips. The pillars were no longer detectable because the cells have pulled themselves up such that in the confluent layer they rest atop the pillars. Inhibition of myosin IIA with blebbistatin caused cells in a confluent layer to relax around the pillars. Thus, myosin‐mediated internal tension was required for monolayer stabilization above the pillars, suggesting that active tension among adjacent endothelial cells in a monolayer dominates mechanotransmission. Time (duration of culturing) rather than cell density appears to be a critical variable that allows for the transition from a subconfluent to a confluent layer. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Small molecule detection by reflective interferometric Fourier transform spectroscopy (RIFTS)
Authors: Pacholski Claudia , Perelman Loren A. , VanNieuwenhze Michael S. , Sailor Michael J. 
Published: March 2009

AbstractA new method for the compensation of matrix effects in biosensing experiments referred to as reflective interferometric Fourier transform spectroscopy (RIFTS) has been developed recently [1]. It employs a porous silicon sensor comprised of two porous silicon layers stacked one on top of the other. The structure has a complicated reflectivity spectrum that can be resolved by FFT analysis leading to three distinctive peaks which are assigned to the layers in the porous silicon structur. If the double layer is appropriately designed, the bottom layer can act as a reference channel. In this paper the specific sensing of small molecules using RIFTS is demonstrated for the first time. Ac‐L‐Lys‐D‐Ala‐D‐Ala has been immobilized to the sensor surface representing the capture probe and vancomycin was used as target analyte. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Novel applications of silicon and porous silicon based EISCAP biosensors
Authors: Mathew Arun , Pandian Ganesh , Bhattacharya Enakshi , Chadha Anju 
Published: March 2009

AbstractWe report the fabrication of potentiometric electrolyte‐insulator capacitor (EISCAP) biosensors based on silicon and porous silicon (PS) substrates with oxide and stacked oxide‐nitride dielectrics. These biosensors have been calibrated for the detection and estimation of bioanalytes like tributyrin and urea, based on enzymatic reactions and have a linear detection range from 0.1 mM to 20 mM of the bioanalyte concentration. These improved sensitivity EISCAP sensors were used for the estimation of the total acid content in rancid butter, estimation of enzyme (Lipase) activity and to estimate total triglyceride levels in blood serum. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic characterization of Cu56Ga28Mn16 microwires
Authors: García C. , Prida V. M. , Vega V. , Llamazares J. L. Sánchez , Suñol J. J. , Escoda Ll. , Sánchez M. L. , Ribot J. , Hernando B. 
Published: March 2009

AbstractThe phase constitution, morphology and magnetic properties were investigated in glass‐coated microwires of the Cu–Ga–Mn ternary system produced by the Taylor–Ulitovsky method. The composition determined by energy dispersive X‐ray EDS microanalysis was Cu56Ga28Mn16. Samples were studied in the as‐cast state and after annealing at 100 °C during 30 minutes. The low‐field temperature dependence of magnetization showed the co‐existence of two ferromagnetic phases in both, as‐cast and annealed samples that persisted after annealing. The Curie temperature of major phase is 125 K, while for the second phase is above room temperature. Hysteresis loops measured at 50 K and 350 K, underlined the ferromagnetic character of both phases, while coercive field decreases with annealing more at low temperature than at 350 K [as‐cast wire: HC = 387 Oe (50 K) and 40 Oe (350 K); annealed wire: HC = 225 Oe (50 K) and 35 Oe (350 K)]. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐field non‐resonant microwave absorption in glass‐coated Co‐rich microwires
Authors: Valenzuela Raul , Montiel Herlinda , Alvarez Guillermo , Zamorano Rafael 
Published: March 2009

AbstractA study of low‐field non‐resonant microwave absorption (LFA) at 9.8 GHz, on as‐cast amorphous Co‐rich CoFeBSi microwires under different measuring geometries is presented. Results confirm that LFA is associated with the magnetization processes from the unmagnetized state (HDC = 0) to the saturated condition, in many aspects similar to Giant Magnetoimpedance (GMI), and clearly different from ferromagnetic resonance (FMR). LFA signal showed large variations in its maximum–minimum separation as a function of the measuring geometry, which is interpreted in terms of the total anisotropy in the process. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanical properties of magnetic Fe‐based and Co‐based amorphous wires and microwires
Authors: Chiriac H. , Lupu N. , Dobrea V. , Corodeanu S. 
Published: March 2009

AbstractIn this paper we present measurements of the mechanical properties of magnetically soft Fe‐based and Co‐based conventional amorphous wires (CAW) and glass‐covered amorphous microwires (GCAW) in the as‐quenched state, before and after cold rolling, and after annealing for internal stresses relief. The tensile strength (σ) varies between 2000 MPa and 3400 MPa, strongly depending on CAW diameter and annealing temperature. The Young modulus (E) is following a descendant trend, decreasing with the diameter decrease. The increase of tensile strength (σ) and elongation (ε) values after cold‐rolling and post‐annealing is caused by the release of the internal stresses induced during the preparation. Tensile strengths up to 3900 MPa are achieved for Fe‐based GCAW, depending very strongly on the microwires diameter, but mostly on the glass cover thickness. σ reaches the maximum value of 3150 MPa for a Co‐based microwire having the glass cover of 9 μm and the total diameter of 43 μm, but increases even more after the glass removal (3350 MPa). This behaviour is attributed to the structural disorder and the specific magnetic domains structure in Fe‐based and Co‐based CAW and GCAW. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evidence of type‐II band alignment at the ordered GaInNP to GaAs heterointerface
Authors: Hsu H. P. , Huang Y. N. , Huang Y. S. , Sitarek P. , Tiong K. K. , Tu C. W. 
Published: March 2009

AbstractPolarized piezoreflectance (PzR) and photoreflectance (PR) are employed to study band alignment in Ga0.46In0.54Ny P1–y /GaAs heterostructures grown by gas‐source molecular‐beam epitaxy. The features near the band edge of Ga0.46In0.54Ny P1–y show strong polarization dependence, indicating the existence of some degree of ordering of these samples. The PR spectra exhibit Franz–Keldysh Oscillations (FKOs) above the band edge of GaAs. The electric fields in the GaAs region are evaluated by analyzing the FKOs and found to decrease with increasing nitrogen content. The type‐II band alignment at the Ga0.46In0.54Ny P1–y /GaAs interface is concluded for the alloys with nitrogen content y larger than 0.5% based on the appearance of additional features below band edge of GaAs. These features are attributed to the spatially indirect type‐II transitions in the vicinity of interface region between Ga0.46In0.54Ny P1–y and GaAs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitonic effects and Franz–Keldysh oscillations in photoreflectance of ultrapure GaAs epilayers
Authors: Komkov O. S. , Glinskii G. F. , Pikhtin A. N. , Ramgolam Y. K. 
Published: March 2009

AbstractA model based on the exciton theory has been presented for lineshape analysis of photoreflectance (PR) spectra. Experimental PR spectra of high‐quality thick GaAs epilayers of different purity were measured to verify the theoretical results. It has been shown that excitonic effects completely prevail over the one‐electron theory in the formation of photoreflectance spectrum even at high electric fields and room temperature, giving evidence of the existence of Franz–Keldysh oscillations enhanced by excitonic effects. A comparison of PR spectra simulated using the exciton theory and the one‐electron approximation has shown that the semiperiods of the oscillations were practically similar. This demonstrates the validity of using the simple “high‐field” model of Aspnes and Studna to determine surface electric fields. In photoreflectance of thick ultrapure GaAs epilayers an oscillating structure was experimentally observed in the region between the excitonic and the fundamental bandgap. This provides a possibility for contactless characterization not only for doped (N ∼ 1014–1018 cm–3) but also for ultrapure (N ∼ 1011–1013 cm–3) GaAs epilayers as well as other semiconductor materials. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fast measurements of photoreflectance spectra by using multi‐channel detector
Authors: Kudrawiec R. , Khachapuridze A. , Cywinski G. , Suski T. , Misiewicz J. 
Published: March 2009

AbstractPhotoreflectance (PR) measurements were performed on GaAs‐ and GaN‐based structures in the so called ‘bright configuration’ where the sample was illuminated by white light (probing beam) instead of monochromatic light as it takes place in the standard configuration, i.e., so‐called ‘dark configuration’. Within this concept the whole PR spectrum can be measured/processed at the same time using a multi‐channel detector (i.e., CCD camera) instead the phase sensitive lock‐in detection system with the one‐channel detector. In this work PR spectra for Si δ‐doped GaAs structure have been measured using both the CCD detector system as well as the standard lock‐in technique with the one‐channel detector system. GaAs‐related Franz–Keldysh oscillations, which are typical of Si δ‐doped GaAs structure, have been clearly observed in PR spectra measured by using the two detection systems. In addition, the PR system with the CCD detector has been used to measure PR spectra in the UV spectral region for an InGaN/GaN/Al2O3 structure. In this case, PR resonances related to InGaN and GaN band gap absorption have been clearly observed. Using the PR system with CCD detector the time of PR measurements was reduced to few seconds for both GaAs‐ and GaN‐based structures. It shows that the bright configuration of PR set‐up with multi‐channel detection system is very promising and perspective in the fast diagnostic of semiconductor structures. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cardioprotective potential of myricetin in isoproterenol‐induced myocardial infarction in wistar rats
Authors: Tiwari Roshan , Mohan Mahalaxmi , Kasture Sanjay , Maxia Andrea , Ballero Mauro 
Published: March 2009

AbstractThe study aimed to evaluate the protective role of myricetin obtained from Vitis vinifera (Vitaceae) on heart rate, electrocardiographic (ECG) patterns, vascular reactivity to catecholamines, cardiac marker enzymes, antioxidant enzymes together with morphological and histopathological changes in isoproterenol (ISO) induced myocardial infarction (MI) in male Wistar rats. Rats treated with isoproterenol (85 mg/kg, administered subcutaneously twice at an interval of 24 h) showed a significant increase in heart rate and ST elevation in ECG, and a significant increase in the levels of cardiac marker enzymes – lactate dehydrogenase (LDH), creatine kinase (CK) and aspartate aminotransferase (AST) in serum. Isoproterenol significantly reduced superoxide dismutase (SOD) and catalase (CAT) activity and increased vascular reactivity to various catecholamines. Pretreatment with myricetin (100 mg/kg, p.o. and 300 mg/kg, p.o.) for a period of 21 days significantly inhibited the effects of ISO on heart rate, levels of LDH, CK, AST, SOD, CAT, vascular reactivity changes and ECG patterns. Treatment with myricetin (100 mg/kg and 300 mg/kg) alone did not alter any of the parameters compared with vehicle treated Wistar rats. Myricetin treated animals showed a lesser degree of cellular infiltration in histopathological studies. Thus, myricetin (100 mg/kg and 300 mg/kg) ameliorates the cardiotoxic effects of isoproterenol and may be of value in the treatment of MI. Copyright © 2009 John Wiley & Sons, Ltd.
Large‐scale effect of aerosols on precipitation in the West African Monsoon region
Authors: Huang J. , Zhang C. , Prospero J. M. 
Published: March 2009

AbstractWe used multi‐year satellite observations to study aerosol effects on the large‐scale variability in precipitation of the West African Monsoon (WAM) region, which is often impacted by high concentrations of desert dust and biomass‐burning smoke. We find a statistically significant precipitation reduction associated with high aerosol concentration near the coast of the Gulf of Guinea from late boreal autumn to winter. The largest aerosol‐related precipitation reduction (∼1.5 mm d−1) is about 50% of the climatological mean precipitation in the region and occurs mainly at rain rates in the range of 2–17 mm d−1 off the northern coast of the Gulf of Guinea. This reduction cannot be linearly attributed to known climate and weather factors such as El Niño–Southern Oscillation, North Atlantic Oscillation, Atlantic sea‐surface temperature, or water vapour. The fractional precipitation variance related to aerosol is about 13%, a value comparable to those related to the known climate factors. Based on the spatial pattern and seasonality of the observed precipitation reduction and its dependence on the rain rate, the observed negative correlation cannot be readily attributed to precipitation effects on aerosol by wet deposition or to rain and cloud contamination of satellite aerosol retrievals. We therefore suggest that our results can be taken as observational evidence of aerosol effects on precipitation. The aerosol associated with the observed precipitation reduction can be traced back to various African sources where large quantities of desert dust and biomass‐burning smoke are emitted during much of the year. Given that the emissions of dust and smoke have varied considerably over the past several decades, in part attributable to human activities, our observed rainfall reduction may reflect an anthropogenic impact to some degree. Copyright © 2009 Royal Meteorological Society
Radiosonde humidity bias correction over the West African region for the special AMMA reanalysis at ECMWF
Authors: Agustí‐Panareda Anna , Vasiljevic Drasko , Beljaars Anton , Bock Olivier , Guichard Françoise , Nuret Mathieu , Garcia Mendez Antonio , Andersson Erik , Bechtold Peter , Fink Andreas , Hersbach Hans , Lafore Jean‐Philippe , Ngamini Jean‐Blaise , Parker Douglas J. , Redelsperger Jean‐Luc , Tompkins Adrian M. 
Published: March 2009

AbstractDuring the African Monsoon Multidisciplinary Analysis (AMMA) field experiment in 2006 there was a large increase in the number of radiosonde data over West Africa. This has the potential of improving the numerical weather prediction (NWP) analysis/forecast and the water budget studies over that region. However, it is well known that the humidity from radiosondes can have some errors depending on sonde type, relative humidity (RH), temperature and the age of the sensor and can give rise to dry biases that are typically between 5% and 30% for RH. Three main sonde types were used in the AMMA field experiment: Vaisala RS80A, Vaisala RS92 and MODEM. In this article, a new empirical method is presented by using the operational European Centre for Medium‐Range Weather Forecasts (ECMWF) short‐range forecast as an intermediary dataset for computing biases. The validation of the correction method using global positioning system (GPS) total columnar water vapour (TCWV) confirms that the method is able to correct for a large part of the dry biases associated with the different sonde types. Results from analysis experiments show how the correction of humidity is particularly important in the West African region due to its impact on the development of convection in NWP models. The proposed radiosonde humidity bias correction has been applied to the special AMMA reanalysis experiment performed at ECMWF for the 2006 West African wet monsoon season. This is expected to benefit a wide number of AMMA‐related studies that make use of the reanalysis, in particular those focusing on the water cycle. Copyright © 2009 Royal Meteorological Society
Subseasonal extremes of precipitation and active‐break cycles of the Indian summer monsoon in a climate‐change scenario
Authors: Turner A. G. , Slingo J. M. 
Published: March 2009

AbstractChanges to the behaviour of subseasonal precipitation extremes and active‐break cycles of the Indian summer monsoon are assessed in this study using pre‐industrial and 2 × CO2 integrations of the Hadley Centre coupled model HadCM3, which is able to simulate the monsoon seasonal cycle reasonably. At 2 × CO2, mean summer rainfall increases slightly, especially over central and northern India. The mean intensity of daily precipitation during the monsoon is found to increase, consistent with fewer wet days, and there are increases to heavy rain events beyond changes in the mean alone. The chance of reaching particular thresholds of heavy rainfall is found to approximately double over northern India, increasing the likelihood of damaging floods on a seasonal basis. The local distribution of such projections is uncertain, however, given the large spread in mean monsoon rainfall change and associated extremes amongst even the most recent coupled climate models. The measured increase of the heaviest precipitation events over India is found to be broadly in line with the degree of atmospheric warming and associated increases in specific humidity, lending a degree of predictability to changes in rainfall extremes. Active‐break cycles of the Indian summer monsoon, important particularly due to their effect on agricultural output, are shown to be reasonably represented in HadCM3, in particular with some degree of northward propagation. We note an intensification of both active and break events, particularly when measured against the annual cycle, although there is no suggestion of any change to the duration or likelihood of monsoon breaks. Copyright © 2009 Royal Meteorological Society
Modified version of revised Deutsch–Märk model for electron impact K‐shell ionization cross‐sections of atoms at relativistic energies
Authors: Haque A. K. F. , Sarker M. S. I. , Patoary M. A. R. , Shahjahan M. , Hossain M. Ismail , Uddin M. Alfaz , Basak A. K. , Saha B. C. 
Published: March 2009

AbstractA simple modification of the revised Deutsch–Märk model (RDM) [Deutsch et al., Int J Mass Spectrom 2004, 233, 13] incorporating both the ionic and relativistic corrections is proposed to investigate the K‐shell ionization of 30 atomic targets with atomic numbers Z = 1–92 for incident energies up to 2 GeV. We also revisit our earlier models: modified Bell (MBELL) (Haque et al., Phys Rev A 2006, 73, 012708) and modified Kolbenstvedt (MKLV) (Uddin et al., Eur Phys J D 2006, 37, 361), for the K‐shell ionization cross sections at these ultra‐relativistic energies. The results from the modified version of RDM (MRDM), MBELL, and MKLV models agree well with the available experimental data and quantum mechanical calculations. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009