bluuebunny/crossref_metadata_2025_split huggingface dataset:
Muscle carnitine in hypo‐ and hyperthyroidism
Authors: Sinclair Christopher , Gilchrist James M. , Hennessey James V. , Kandula Manju 
Published: March 2005

AbstractWeakness is common in both hyper‐ and hypothyroidism, and skeletal muscle L‐carnitine may play a role in this regard, as suggested by studies indicating abnormal levels of carnitine in serum and urine of patients with thyroid dysfunction. Skeletal muscle samples were obtained for carnitine analysis from control subjects, and from hyperthyroid and hypothyroid patients before and after treatment. There was a significant reduction in carnitine, especially the esterified portion, in hyperthyroid individuals, with a return to normal as euthyroid status was regained. In hypothyroid patients, there was a trend for carnitine to be lower than normal and for improvement once euthyroid status was attained. Our data indicate that muscle carnitine levels are affected by both hypo‐ and hyperthyroidism. A decrease in muscle carnitine in both conditions may contribute to thyroid myopathy. Muscle Nerve, 2005
Silicon light‐emitting diodes based on dislocation‐related luminescence
Authors: Kveder V. , Badylevich M. , Schröter W. , Seibt M. , Steinman E. , Izotov A. 
Published: March 2005

AbstractWe investigated correlation between concentration of deep level defects at dislocations, detected by deep level transient spectroscopy (DLTS) and the efficiency of dislocation related luminescence in Si samples with dislocation density of about (3–5) × 108 cm–2. We show that significant reduction of concentration of deep states at dislocations achieved by using the combination of gettering and passivation, results in a drastic (by several orders of magnitude) increase of dislocation‐related D1 luminescence in a high temperature range. As a consequence, electroluminescence (EL) from dislocation related D1‐line reaches an external efficiency more then 0.1% at room temperature. Concentration of D1 and D2 luminescence centers, roughly estimated from the optical absorption spectrum, was found to be of the order of 3 × 1014 cm–3 for dislocation density of about 5 × 108 cm–2. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defects in germanium‐doped Czochralski silicon
Authors: Yang Deren 
Published: March 2005

AbstractGermanium doping of Czochralski (CZ) silicon has attracted attention in recent years. It is pointed out that germanium doping can result in denser voids with small size, which can be eliminated easily by annealing at high temperature, and may improve the gate oxide integrity (GOI) of semiconductor devices. Meanwhile, oxygen precipitation in CZ silicon can be enhanced by germanium, so that the internal gettering (IG) ability of wafers is improved. In addition, it is reported that germanium can suppress the formation of thermal donors (TDs). Thus, it is believed that the germanium‐doped CZ (GCZ) silicon can be used as the substrate of ultra‐large scale integrated (ULSI) circuits, which have the high quality subsurface layer, the high IG ability, and the stable electrical property. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the nucleation of shuffle dislocations in Si
Authors: Rabier J. , Demenet J. L. 
Published: March 2005

AbstractDifferent types of dislocation core are evidenced in silicon depending on the deformation conditions. Perfect (shuffle) dislocations are found for high applied stresses whereas dissociated (glide) dislocations result from the application of moderate or low stresses. This paper is devoted to the characterization of such a transition and the possible transformation from one type of core to the other type of core. Experimental results suggest that these two types of dislocations are nucleated in two different ranges of temperature and stress rather than resulting from core transformations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interfacial structure of MBE grown InN on GaN
Authors: Kehagias Th. , Iliopoulos E. , Delimitis A. , Nouet G. , Dimakis E. , Georgakilas A. , Komninou Ph. 
Published: March 2005

AbstractThe structural properties of the interfacial area of InN thin films, grown by rf‐plasma MBE on top of GaN/Al2O3 substrates have been investigated by TEM and HRTEM. Continuous or columnar film growth highly depends on the pre‐growth of an InN nucleation layer and low substrate temperatures. The lattice constants in both growth cases were determined by electron diffraction analysis. A network of 60° misfit dislocations was introduced in the InN/GaN interface to accommodate the lattice mismatch between the two crystals. The degree of residual compressive strain in the continuous film is also calculated, considering the columnar film closer to the relaxed configuration. The good agreement between the experimental and the calculated value for the misfit dislocation spacing provides evidence that the residual compressive strain is minimized. The in‐plane lattice expansion, observed in the continuous InN film, is attributed to thermal tensile strain originating from the difference in the thermal expansion coefficients of InN and GaN. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carrier diffusion and recombination in highly excited InGaN/GaN heterostructures
Authors: Jarašiūnas K. , Aleksiejūnas R. , Malinauskas T. , Sūdžius M. , Miasojedovas S. , Juršėnas S. , Žukauskas A. , Gaska R. , Zhang J. , Shur M. S. , Yang J. W. , Kuokštis E. , Khan M. A. 
Published: March 2005

AbstractTime‐resolved four‐wave mixing and photoluminescence techniques have been combined for studies of MOCVD‐grown InxGa1–xN/GaN/sapphire heterostructures with different indium content (0.08 < x < 0.15). In‐plane diffusion and recombination of spatially‐modulated carriers, confined in the front layer of 50‐nm‐thick InGaN, were monitored by a probe beam diffraction and provided an average value of a bipolar diffusion coefficient D ≈ 1–1.5 cm2/s and its dependence on the In content. A complete saturation of four‐wave mixing (FWM) efficiency vs excitation energy was found prominent in a layer with 10% of In. The latter effect of saturation correlated well with the dependence of quantum efficiency of stimulated emission on In content in heterostructures. Short decay times of stimulated emission (∼10 ps) measured by time‐resolved PL in highly excited structure allowed us to attribute the FWM saturation effect to the threshold of stimulated recombination. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Atomic simulations and HRTEM observations of a Σ 18 tilt grain boundary in GaN
Authors: Kioseoglou J. , Béré A. , Komninou Ph. , Dimitrakopulos G. P. , Nouet G. , Iliopoulos E. , Serra A. , Karakostas Th. 
Published: March 2005

AbstractThe crystalline quality of GaN thin films grown on foreign substrates for opto‐ and micro‐electronics applications depends strongly on the growth conditions. Among a variety of microstructural defects that appear in GaN epilayers, grain boundaries (GBs) are extended defects that may be formed during the growth process under certain circumstances. In this work, the atomic structures of a ‘symmetric' and an ‘asymmetric' 70.53° 〈$ 1 \bar 2 10$〉 Σ18 tilt boundaries are investigated by combining large scale energetic calculations, using a modified Stillinger–Weber interatomic potential, with high resolution transmission electron microscopy observations. The energetically favourable short‐period asymmetric interface is matched to the experimental observations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Enhancement effect of Tb‐related luminescence in AlxGa1–xN with the AlN molar fraction 0 ≤ x ≤ 1
Authors: Wakahara A. , Nakanishi Y. , Fujiwara T. , Yoshida A. , Ohshima T. , Kamiya T. 
Published: March 2005

AbstractEffects of Al composition on luminescence properties corresponding to Tb3+ inner level transitions are investigated. When the Al composition is larger than 0.3, luminescence corresponding to 5D4–7FJ (J = 3, 4, 5, 6) transitions is observed at room temperature, while 5D3–7FJ transition such as 5D3–7F5 can be observed only at low temperature. As the Al composition increases, the luminescence intensity is increased super linearly at first, and then linearly increased. Thermal quenching of luminescence intensity is dramatically improved as increasing the Al composition. Major effect of AlGaN is well explained by reduction of energy‐back‐transfer process. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of lattice matched InxGa1–xP1–yNy heteroepitaxial layers on GaP
Authors: Imanishi T. , Wakahara A. , Kim S. M. , Yonezu H. , Furukawa Y. 
Published: March 2005

AbstractOptical constants and band structure of InxGa1–xP1–yNy lattice matched to GaP (100) substrate are investigated. Nitrogen concentration in the film estimated by X‐ray diffraction and X‐ray photoelectron spectroscopy, was 1.4%, 1.8% and 3.5%. Refractive index and transition critical points E0 (Γv to Γc), E1 (Lv to Lc) and E2 (Xv to Xc) are evaluated by spectroscopic ellipsometry. When N composition increases from 1.4% to 3.5%, both photoluminescence (PL) peak energy, EPL, and E0 shift to lower energy, and the energy difference ΔE = E0 – EPL decrease from 380 meV to 110 meV. The large red‐sift of EPL from the E0 suggest that the luminescence is of defect‐related luminiscence, and crossover point of indirect band structure estimated by the extrapolation of N‐composition dependence of ΔE is estimated to be arroud in In0.1Ga0.9P0.96N0.04. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Uniform III‐nitride growth in single wafer horizontal MOVPE reactors
Authors: Hardtdegen H. , Kaluza N. , Steins R. , Javorka P. , Wirtz K. , Alam A. , Schmitt T. , Beccard R. 
Published: March 2005

AbstractUsing a new susceptor set‐up a systematic study on gas phase transport properties was carried out with the aim of obtaining layer uniformity. By determining the influence of the transport parameters on growth it is then possible to achieve symmetric growth profiles and highly uniform GaN and AlGaN layers as well as heterostructures exhibiting a high material quality with respect to their structural and electrical properties. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature dependence of carrier lifetimes in InN
Authors: Chen Fei , Cartwright A. N. , Lu H. , Schaff W. J. 
Published: March 2005

AbstractTime‐resolved pump–probe transmission measurements were used to determine the temperature dependence of carrier lifetime for InN epilayers with unintentionally doped levels from 1018 to 1019 cm–3. The observed decay time at 20 K is well explained by a dominating radiative interband recombination, while at room temperature it is attributed to a defect related nonradiative recombination channel. The temperature dependence of the radiative lifetime is deduced from the measurements of both differential transmission decay time and PL intensity. For the best quality sample, we find the radiative lifetime increases proportionally to T3/2, as theory predicts when a k‐selection rule holds, which suggests that the radiative band‐to‐band transition accounts for the observed infrared photoluminescence over the entire temperature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Advanced characterization techniques of nonuniform indium distribution within InGaN/GaN heterostructures grown by MOCVD
Authors: Lu D. , Florescu D. I. , Lee D. S. , Ramer J. C. , Parekh A. , Merai V. , Li S. , Gardner J. J. , Begarney M. J. , Armour E. A. 
Published: March 2005

AbstractNonuniform indium distribution within InGaN/GaN single quantum well (SQW) structures with nanoscale islands grown by metalorganic chemical vapor deposition (MOCVD) have been characterized by advanced characterization techniques. Robinson backscattered electron (BSE) measurements show cluster‐like BSE contrast of high brightness regions, which are not centered at small dark pits in a SQW structure of spiral growth mode. By comparing with the secondary electron (SE) images, the bright cluster areas from the BSE images were found to have higher indium content compared to the surrounding dark areas. Temperature dependant photoluminescence (PL) measurement shows typical “S‐shape” curve, which shows good correlation with nonuniform indium distribution from BSE measurement. Optical evaluation of the samples show increased PL slope efficiency of the spiral mode SQW, which can be attributed to the presence of Indium inhomogeneities. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparative analysis of hot‐electron transport in AlGaN/GaN and AlGaN/AlN/GaN 2DEG channels
Authors: Ardaravičius L. , Ramonas M. , Kiprijanovic O. , Liberis J. , Matulionis A. , Eastman L. F. , Shealy J. R. , Chen X. , Sun Y. J. 
Published: March 2005

AbstractNanosecond‐pulsed current–voltage measurements were used to study hot‐electron transport in undoped AlGaN/GaN and AlGaN/AlN/GaN two‐dimensional electron gas channels biased up to 200 kV/cm. Voltage pulses of 1 ns were applied in order to minimize channel heating. The current saturated at 100 kV/cm in the AlN‐interbarrier‐contained structures; the estimated saturated drift velocity was about 1.1 × 107 cm/s. No saturation of the current was observed in AlGaN/GaN channels in the field range below 200 kV/cm. Monte Carlo simulation of hot‐electron transport was carried out with electron gas degeneracy and hot phonons taken into account. A fairly good fit of the experimental results with the Monte Carlo simulation data was obtained in the electric field range up to 30 kV/cm. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrospray ionization ion trap mass spectrometry for structural characterization of oligosaccharides derivatized with 2‐aminobenzamide
Authors: Morelle Willy , Page Adeline , Michalski Jean‐Claude 
Published: March 2005

AbstractThe use of electrospray ionization (ESI) quadrupole ion trap mass spectrometry and reversed‐phase high‐performance liquid chromatography (HPLC) for the characterization of 2‐aminobenzamide (2AB)‐labeled oligosaccharides and N‐linked protein oligosaccharide mixtures is described. The major signals were obtained under these conditions from the [M+Na]+ ions for all 2AB‐derivatized oligosaccharides. Under collision‐induced dissociation, sodiated molecular species generated in the ESI mode yield simple and predictable mass spectra. Tandem mass spectrometry (MS/MS) experiments with orders higher than two offer a number of ways to enhance MS/MS spectra and to derive information not present in MS and MS2 spectra. Information on composition, sequence, branching and, to some extent, interglycosidic linkages can be deduced from fragments resulting from the cleavage of glycosidic bonds and from weak cross‐ring cleavage products. Reversed‐phase HPLC and derivatization by reductive amination using 2‐aminobenzamide were finally applied to characterize a glycan pool enzymatically released from glycoproteins. Copyright © 2005 John Wiley & Sons, Ltd.
Determination of atomic hydrogen in non‐thermal hydrogen plasmas by means of molecular beam threshold ionization mass spectrometry
Authors: Wang Wei‐Guo , Xu Yong , Yang Xue‐Feng , Wang Wen‐Chun , Zhu Ai‐Min 
Published: March 2005

AbstractAtomic hydrogen plays important roles in chemical vapor deposition of functional materials, plasma etching and new approaches to chemical synthesis of hydrogen‐containing compounds. The present work reports experimental determinations of atomic hydrogen near the grounded electrode in medium‐pressure dielectric barrier discharge hydrogen plasmas by means of molecular beam threshold ionization mass spectrometry (MB‐TIMS). At certain discharge conditions (a.c. frequency of 24 kHz, 28 kV of peak‐to‐peak voltage), the measured hydrogen dissociation fraction is decreased from ∼0.83% to ∼0.14% as the hydrogen pressure increases from 2.0 to 14.0 Torr. A simulation method for extraction of the approximate electron beam energy distribution function in the mass spectrometer ionizer and a semi‐quantitative approach to calibrate the mass discrimination effect caused by the supersonic beam formation and the mass spectrometer measurement are reported. Copyright © 2005 John Wiley & Sons, Ltd.
Vertically Aligned Carbon‐Nanotube Arrays Showing Schottky Behavior at Room Temperature
Authors: Jung Seung‐Ho , Jeong Soo‐Hwan , Kim Sang‐Uck , Hwang Sun‐Kyu , Lee Pyung‐Soo , Lee Kun‐Hong , Ko Ju‐Hye , Bae Eunju , Kang Donghun , Park Wanjun , Oh Hwangyou , Kim Ju‐Jin , Kim Hyungseok , Park Chan‐Gyung 
Published: March 2005

AbstractVertically aligned carbon‐nanotube (CNT) arrays were fabricated in the thin‐film anodic aluminum oxide (AAO) templates on silicon wafers utilizing a niobium (Nb) thin film as the source electrode. The average diameter of the CNTs was 25 nm, and the number density was 3×1010 cm−2. The CNT arrays synthesized at 700 °C and above exhibited Schottky behavior even at 300 K, with energy gaps between 0.2 eV and 0.3 eV. However, individual CNTs obtained by removal of the template behaved as resistors at 300 K. The CNT/Nb oxide/Nb junction is thought to be responsible for the Schottky behavior. This structure can be a useful cornerstone in the fabrication of nanotransistors operating at room temperature.
The diet and trophic ecology of anglerfish Lophius piscatorius at the Shetland Islands, UK
Authors: Laurenson C.H. , Priede I.G. 
Published: March 2005

The diet of anglerfish (Lophius piscatorius), based on the analysis of stomach contents, was investigated in the Shetland Islands. Samples were obtained during trawling for sandeel (Ammodytidae species) and demersal trawling when mainly whitefish (gadoids) are targeted. This allowed the diets of samples collected from different areas and at different times to be compared. The diets in different length groups were also compared and niche breadth investigated.A wide range of prey types, mainly fish, were recorded but the main prey was Norway pout (Trisopterus esmarkii) and lesser sandeel (Ammodytes marinus). Diet composition varied seasonally. In samples collected during whitefish trawling the occurrence of empty stomachs decreased from the first to the third quarters and generally increased with increasing anglerfish size. Empty stomachs occurred less frequently in samples collected from areas where sandeel fishing occurred compared to areas where whitefish trawling occurred.
Risk impacts on the economic performance of oil and gas projects in Nigeria
Authors: Omole Olusegun , Borisade T.A. , Muhammad Ahmad 
Published: March 2005

AbstractDespite the risks and uncertainties associated with investment in the petroleum industry, Nigeria remains attractive to foreign investors, due (partly) to the high rate of return on investment, the presence of a prodigious hydrocarbon base and the existence of a reliable legal framework for the protection of such investment. This study attempts to identify the key elements of risks and uncertainties in the Nigerian oil and gas industry and their associated impacts on the economic performance of capital projects, using data obtained from experts in the industry. The study reveals that the reservoir area, the hydrocarbon formation thickness, the porosity, the production drive mechanism and, hence, the recovery factor are the most significant uncertainty factors in oil exploitation. The major economic uncertainties identified include the crude oil price and joint venture cash calls (the latter is currently on the decline, due to the improved Government commitment to its cash call obligations).
A review of upstream development policies in Kuwait
Authors: Al‐Attar Abdulaziz E. 
Published: March 2005

AbstractSince 1993, Kuwait's legislative bodies have been looking closely at the prospect of opening‐up the country's upstream oil sector for development and production to international oil companies (IOCs). The country has proposed doing this by means of a mechanism called an “operating service agreement” (OSA). This has generated controversy. One side argues that opening‐up the oil sector embodies a pattern of denationalisation and is reminiscent of the country's former concession agreement of 1934. And the other side maintains that the proposed OSA is unquestionably different to the concession agreement, in terms of legal framework, fiscal system and the role of the state. This paper reviews and compares the two types of agreement.It then discusses the impact of improved oil recovery factors on increasing oil reserves and production in the northern and western Kuwaiti oil fields, by transferring technology from industrialised countries.
The impact of downstream refinery concerns on the international oil market
Authors:   OPEC Secretariat
Published: March 2005

AbstractThis article looks at the difficulties experienced by the international oil market in 2004, in the context of the heavy pressure that has been put on stability and prices by downstream refinery problems, even though the market has remained well‐supplied with crude. It notes the efforts OPEC has made to maintain a reasonable market balance, in particular by accelerating the implementation of production expansion plans to increase the excess supply cushion. But it seems that, along with a tight market for light sweet crude oil, problems in the downstream sector will remain major upside risks for the market in 2005, risks that require urgent attention.
Proposed mechanism for the origin of sodic patches in Kruger National Park, South Africa
Authors: Khomo L. M. , Rogers K. H. 
Published: March 2005

AbstractThe accumulation of sodium on the footslopes of granitic catenas in semi‐arid southern Africa leads to the formation of sodic patches. Sodic patches are ecologically important for nutrient accumulation, predator evasion and wallowing, but they are often perceived as derelict lands because of vegetation denudation and low aesthetic quality. This negative perception, by both ecologists and tourists, often leads to ill‐advised management and ‘rehabilitation’ measures. In Kruger National Park, sodic patches occur at the riparian‐upland boundary and hence the processes originating in both systems may contribute to their origin. The upland‐based catena and riparian‐based evapotranspiration models were used to explore the hypothesis that these soils originate from both catena and evapotranspiration‐driven hydraulic processes. The models predict vegetation zonation dictated by a salt tolerance gradient and an increase in sodic patch area over time as a result of progressive salt accumulation. Vegetation structure and hillslope morphology across the riparian‐upland boundary and analysis of change in patch configuration over a 50‐year aerial photographic record were used to test the hypotheses. Sodic patches have unique vegetation, occur on the intermediate positions of hillslopes, have increased in area three‐fold over 50 years and are encroaching into the riparian zone. This behaviour is consistent with the assertion that these patches originate from both catena and evapotranspiration processes. Results imply a dynamic aspect of sodic patches, which have been previously viewed as static landscape features in pedogenic time scales. However, we show that they change over relatively smaller time scales meaning that their management should be commensurate with this dynamic nature. Therefore, sodic patches should be managed under a scheme that incorporates their small‐scale expansion and recognizes their ecological importance.