bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion implantation induced disorder in single‐crystal and sputter‐deposited polycrystalline CdTe characterized by ellipsometry and backscattering spectrometry
Authors: Petrik P. , Khánh N. Q. , Li Jian , Chen Jie , Collins R. W. , Fried M. , Radnóczi G. Z. , Lohner T. , Gyulai J. 
Published: March 2008

AbstractBulk single‐crystal CdTe, sputter‐deposited polycrystalline CdTe films of about 2.5 micron thickness, and single‐crystal Si (c‐Si) have been ion implanted using 350 keV Xe at fluences ranging from 1×1013 to 16×1013 cm–2 so as to create disorder in a controlled way from fully single‐crystalline to fully amorphous material. The general purpose of the investigations is to seek a parameterization of the critical point structures and establish a database for fitting the optical properties of CdTe films having different unknown grain sizes whereby the grain size will be described in terms of an effective defect density. The polycrystalline CdTe samples were magnetron sputtered onto c‐Si followed by CdCl2 and Br2‐methanol treatment to improve properties in terms of grain size and surface smoothness, respectively. The fluences for use in the ion implantation of CdTe were estimated using the SRIM (Stopping and Range of Ions in Matter) software, and cross‐checked by simultaneous implantation of bulk c‐Si samples. The optical properties were characterized by second derivative analysis and by a generalized critical point model. Although the damage created by 350 keV Xe in the simultaneously implanted c‐Si samples, as measured by both spectroscopic ellipsometry and Rutherford backscattering/ channeling spectrometry (RBS/C), agrees well with the expectations based on the SRIM simulation, the damage created in CdTe remains at a very low level even for doses several times higher than the amorphization level estimated by simulation. The character of the dechanneling of the RBS/C spectra indicates extended defects (presumably dislocation loops). This effect was similar in both single‐crystal and thin film polycrystalline CdTe, although less pronounced in thin film samples. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of ellipsometry in immersion lithography
Authors: Jeong H. , Cheon H. , Kyoung J. , Oh H. , An* I. 
Published: March 2008

AbstractOptical lithography with an ArF excimer laser (193 nm) can produce sub 100nm patterns. Without the reduction of wavelength, further increase in resolution is expected by employing an immersion technique in which a liquid medium is filled between the objective lens and underlying photoresist. In this case, resolution can be enhanced through the increase of numerical aperture. However, in order for immersion lithography to be successful, many problems associated with the liquid environment need to be solved. One of the serious problems is the interaction between liquid and photoresist. Liquid may penetrate into the photoresist and cause leaching problem. This in turn modifies the physical and chemical properties of the photoresist. Thus, it is important to monitor the modification of the photoresist by immersion liquid. In this work, spectroscopic ellipsometry and imaging ellipsometry are used to investigate the absorption of liquid by photoresist as well as top coat which is used to prevent water penetration into underlying photoresist. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigations of deep lying wide bandgap GaN and InGaN quantum well structures: A challenge for ellipsometric methods
Authors: Rossow U. , Fuhrmann D. , Jönen H. , Hangleiter A. 
Published: March 2008

AbstractIn this contribution we address the problems in characterizing typical group‐III‐nitride QW structures used in LED or laser applications by spectroscopic ellipsometry. Since the buffer layers are transparent in the visible and near UV and the whole layer stack is a few microns thick, the contributions of the nanometer thick QWs to the signal is very small and with ellipsometers with typical resolution in the polarization states hardly to detect. We discuss this in detail for two typical structures – Al‐GaN/GaN and InGaN/GaN – and quantify how the resolution must be improved to overcome this experimental limitation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical Hall effect studies on modulation‐doped AlxGa1–xAs:Si/GaAs quantum wells
Authors: Hofmann T. , von Middendorff C. , Gottschalch V. , Schubert M. 
Published: March 2008

AbstractWe study the temperature (10 K … 293 K) dependence of the optical Hall effect (OHE) in modulationdoped Alx Ga1–x As:Si / GaAs (x = 0.45) superlattice structures with different quantum well thickness (dGaAs = 16.9 nm and dGaAs = 3.7 nm) using generalized magnetooptic ellipsometry at far‐infrared wavelengths. Free electrons are identified within the wells, but not within the doped barriers. The observed OHE can be fully explained within the Drude model and thermionic rate equations. The quantum‐well free electron density (N = 1.3 × 1017 cm–3) increases five times upon sample cooling within the wells with dGaAs = 3.7 nm, and remains constant within the wells with dGaAs = 16.9 nm. We describe this behavior as a steady state of three quantum well electron condensation processes: Coulombactivation of electron states at the Alx Ga1–x As/GaAs interface, quantum‐well‐barrier reservoir interaction, and irreversible electron emission into the host crystal. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large enhancement of the thermoelectric Seebeck coefficient for amorphous oxide semiconductor superlattices with extremely thin conductive layers
Authors: Ohta Hiromichi , Huang Rong , Ikuhara Yuichi 
Published: March 2008

AbstractHerein we demonstrate that amorphous oxide semiconductor (AOS) superlattices composed of a‐In–Zn–O (well) and a‐In–Ga–Zn–O (barrier) layers, fabricated on SiO2 glass substrate by pulsed laser deposition at room temperature, exhibited an enhanced Seebeck coefficient |S |. The |S | value increases drastically with decreasing a‐In–Zn–O thickness (dIZO) when dIZO < ∼5 nm, and reached 73 µV K–1 (dIZO = 0.3 nm), which is ∼4 times larger than that of bulk |S |3D (19 µV K–1), while it kept its high electrical conductivity, clearly demonstrating that the quantum size effect can be utilized in AOS superlattices. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conservation of polymers: a view to the future
Authors: Abel Marie‐Laure , Coppitters Camille 
Published: March 2008

AbstractAs a further extension of the role of surface analysis in the study of early polymeric conservation artefacts, experiments were conducted to study the morphology and chemistry of fractured thermoplastic beads originating from 1970s jewellery. Two different methods were used to prepare the surfaces, either by breaking the object in compression or using liquid nitrogen to render it brittle.Scanning electron microscope (SEM) was used to obtain the morphology, whereas x‐ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF‐SIMS) provided the chemistry of the system. The major component of the objects is established as being polystyrene and the presence or absence of certain additives may be observed, particularly at the surface of the bead or at the surface of samples cracked in a vice. The beads exhibit discolouration and cracking. Hexagonal structures of a few micrometers in diameter are also visible if the morphology is examined at high magnification. Such structures are consistent with stress, crazing, photodegradation and exposure of polystyrene to solvents.Furthermore, it was possible to correlate the presence or absence of additives with the morphologies encountered on the surfaces. Indeed the most damaged samples seemed to be characterised by the absence of additives while exhibiting a composition close to pure polystyrene. Copyright © 2008 John Wiley & Sons, Ltd.
The structure study of amorphous nanocrystalline nanocomposite films of germanium by AFM and EXAFS methods
Authors: Valeev Rishat G. , Deev Andrew N. , Surnin Dmitry V. , Kriventsov Vladimir V. , Karban Oksana V. , Vetoshkin Vladimir M. , Pivovarova Olesya I. 
Published: March 2008

AbstractThe amorphous nanocrystalline semiconductor nanocomposites obtained by evaporation in ultrahigh vacuum at different substrate temperatures show anomalous electro‐physical properties. It may be connected with the structure of clusters which may consist of both crystalline and amorphous phases. The volume portion of the amorphous phase to the nanosized particles can be obtained by the extended x‐ray absorption fine structure (EXAFS) method. In this work we investigate the structure changes of thin nanocomposite films of Ge obtained at condensation temperatures in the range of 25–250 °C by Atomic force microscopy (AFM) and EXAFS methods. Using the method described by Valeev et al. it was shown that the sizes of nanocrystallites in an amorphous matrix vary essentially according to obtaining conditions (according to AFM data); their content vary from 10 to 90%. Copyright © 2008 John Wiley & Sons, Ltd.
Soft X‐ray emission electron microscopy: chemical state microscopy from interface and bulk
Authors: Zimina A. , Batchelor D. R. , Eisebitt S. , Schmeisser D. , Shulakov A. , Eberhardt W. 
Published: March 2008

AbstractScanning electron microscopy (SEM) has long been a workhorse of materials science and provides information on morphology, structure and elemental composition. However, information as to the chemical state of the elements is only available for deep lying core levels of the heavy elements and not the light elements. Whilst considerable advances have been made in high‐resolution wavelength dispersive spectroscopy (WDS) and energy dispersive spectroscopy (EDS), electron microscopy in the soft X‐ray region of ≈ 50–1500 eV is lacking. We present first results for a combined instrument of a soft X‐ray emission (SXE) spectrometer together with a spatially resolving (<100 nm) electron gun. Copyright © 2008 John Wiley & Sons, Ltd.
Increased expression of LIGHT/TNFSF14 and its receptors in experimental and clinical heart failure☆
Authors: Dahl Christen Peder , Gullestad Lars , Fevang Børre , Holm Are M. , Landrø Linn , Vinge Leif Erik , Fiane Arnt E. , Sandberg Wiggo J. , Otterdal Kari , Frøland Stig S. , Damås Jan Kristian , Halvorsen Bente , Aukrust Pål , Øie Erik , Yndestad Arne 
Published: March 2008

AbstractBackground:Clinical and experimental studies suggest a pathogenic role for inflammation in chronic heart failure (HF). LIGHT is a member of the tumour necrosis factor superfamily involved in innate and adaptive immune responses.Aims:We sought to investigate a potential pathogenic role of LIGHT in chronic HF.Methods:We used various clinical and experimental approaches including studies in post‐infarction HF rats and in vitro studies of endothelial cells and peripheral blood mononuclear cells (PBMC).Results:Our main findings were: (i) LIGHT and its receptors (i.e., HVEM and lymphotoxin‐β receptor) were regulated during experimental HF, with strong expression in the infarcted area accompanied by up‐regulation of HVEM in cardiomyocytes and endothelial cells also in the non‐ischaemic part of the left ventricle. (ii) Patients with chronic HF had significantly increased expression of LIGHT on CD3+ T‐cells accompanied by increased expression of HVEM on monocytes and within the failing myocardium. (iii) LIGHT induced interleukin (IL)‐6 expression in endothelial cells. In HF patients, but not in healthy controls, such an IL‐6‐inducing effect was also seen in LIGHT activated PBMC.Conclusion:Our findings in both clinical and experimental HF may suggest a role for LIGHT signalling pathways in the progression of chronic HF involving IL‐6‐related mechanisms.
Celecoxib modulates hypertrophic signalling and prevents load‐induced cardiac dysfunction
Authors: Jacobshagen Claudius , Grüber Meike , Teucher Nils , Schmidt Albrecht G. , Unsöld Bernhard W. , Toischer Karl , Nguyen Van Phuc , Maier Lars S. , Kögler Harald , Hasenfuss Gerd 
Published: March 2008

AbstractIn human hearts, the transition from cardiac hypertrophy to advanced heart failure (HF) is accompanied by a tremendous increase in Akt phosphorylation. In non‐myocardial tissue, the cyclooxygenase (COX)‐2 inhibitor celecoxib has been shown to COX‐independently inhibit Akt signalling.We studied the effects of celecoxib on Akt signalling and hypertrophic response in myocardium. In rabbit isolated cardiac myocytes celecoxib concentration‐dependently (10–100 μmol/L) inhibited the insulin‐induced increase in phosphorylation of Akt and its downstream targets, GSK‐3β and p70 S6 kinase, by reducing the phosphorylation level of the upstream regulator PTEN. Inhibition of Akt signalling was accompanied by a significant suppression of characteristic features of cardiac hypertrophy: Celecoxib concentration‐dependently suppressed the agonist‐induced enhancement of total protein synthesis and BNP mRNA expression.In mice (C57BL/6NCrl) subjected to left ventricular (LV) pressure overload by aortic banding, celecoxib treatment (50 mg·kg−1·d−1) significantly attenuated LV dilation and contractile dysfunction compared with placebo‐treated mice. Moreover, celecoxib significantly reduced mortality 8 weeks after banding.Thus, celecoxib can be used to titrate Akt signalling and hypertrophic response in myocardium. It reduces load‐induced LV dilation, contractile dysfunction and mortality in vivo. This may have clinical implications for the prevention and treatment of maladaptive hypertrophy and its progression to HF in humans.
Tissue inhibitor of metalloproteinases levels in patients with chronic heart failure: An independent predictor of mortality
Authors: Frantz S. , Störk S. , Michels K. , Eigenthaler M. , Ertl G. , Bauersachs J. , Angermann C.E. 
Published: March 2008

AbstractBackground:Matrix metalloproteinases (MMP) and their tissue inhibitors (TIMP) are involved in cardiac remodelling. The prognostic utility of TIMP is unknown in chronic heart failure (CHF).Aims:We investigated the association of plasma levels of soluble MMP‐9 and TIMP‐1 with clinical, laboratory and echocardiographic parameters and estimated their prognostic value in the prediction of all‐cause death.Methods:MMP‐9, TIMP‐1, tumour necrosis factor‐α, and amino‐terminal pro‐brain natriuretic peptide were measured in 249 consecutively enrolled CHF patients and 74 healthy individuals.Results:After adjustment for age, sex and creatinine, levels of TIMP‐1 (1640 vs. 735 ng/ml, P < 0.001) but not MMP‐9 were elevated in CHF patients compared to controls. During a median follow‐up period of 2.5 years, 66 patients (27%) died. In multivariable Cox regression models TIMP‐1 but not MMP‐9 emerged as an independent predictor of all‐cause death (hazard ratio per tertile, 3.5; 95% confidence interval [CI], 2.2–5.1). In addition to the full set of univariately predictive clinical and serological markers, information on TIMP‐1 significantly increased the area under the receiver operating characteristic curve from 0.77 (95% CI, 0.71–0.84) to 0.87 (95% CI, 0.82–0.92).Conclusion:In stable CHF patients, TIMP‐1 but not MMP‐9 is of independent and incremental value regarding the prediction of all‐cause death.
Sustained‐release oral morphine versus transdermal fentanyl and oral methadone in cancer pain management
Authors: Mercadante Sebastiano , Porzio Giampiero , Ferrera Patrizia , Fulfaro Fabio , Aielli Federica , Verna Lucilla , Villari Patrizia , Ficorella Corrado , Gebbia Vittorio , Riina Salvatore , Casuccio Alessandra , Mangione Salvatore 
Published: March 2008

AbstractPurpose: The aim of this study was to compare the analgesic and adverse effects, doses, as well as cost of opioid drugs, supportive drug therapy and other analgesic drugs in patients treated with oral sustained‐release morphine, transdermal fentanyl, and oral methadone.Patients and methods: One hundred and eight cancer patients, no longer responsive to opioids for moderate pain, were selected to randomly receive initial daily doses of 60mg of oral sustained‐release morphine, 15mg of oral methadone, or 0.6mg (25μg/h) of transdermal fentanyl. Oral morphine was used as breakthrough pain medication during opioid titration. Opioid doses, pain intensity, adverse effects, symptomatic drugs, were recorded at week intervals for 4weeks. Costs of opioid therapy, supportive drugs, and other analgesic drugs were also evaluated.Results: Seventy patients completed the 4weeks period of study. Five, five, and four patients, treated with oral morphine, transdermal fentanyl, and oral methadone, respectively, required opioid switching. No differences in pain and symptom intensity were observed. Opioid escalation index was significantly lower in patients receiving methadone (p<0.0001), although requiring up and down changes in doses. At the doses used, methadone was significantly less expensive (p<0.0001), while the use and costs of supportive drugs and other analgesics were similar in the three groups. No relevant differences in adverse effects were observed among the groups during either the titration phase and chronic treatment.Conclusion: All the three opioids used as first‐line therapy were effective, well tolerated, and required similar amounts of symptomatic drugs or co‐analgesics. Methadone was significantly less expensive, but required more changes, up and down, of the doses, suggesting that dose titration of this drug requires major clinical expertise.
Velocity and temperature derivatives in high-Reynolds-number turbulent flows in the atmospheric surface layer. Part 2. Accelerations and related matters
Authors: GULITSKI G. , KHOLMYANSKY M. , KINZELBACH W. , LÜTHI B. , TSINOBER A. , YORISH S. 
Published: March 2008

We report the first results of an experiment, in which explicit information on all velocity derivatives (the nine spatial derivatives, ∂ui∂xj, and the three temporal derivatives, ∂ui/∂t) along with the three components of velocity fluctuations at a Reynolds number as high asReλ~104is obtained. No use of the Taylor hypothesis was made, and this allowed us to obtain a variety of results concerning acceleration and its different Eulerian components along with vorticity, strain and other small-scale quantities. The field experiments were performed at five heights between 0.8 and 10m above the ground.The report consists of three parts. Part 1 is devoted to the description of facilities, methods and some general results. Part 2 concerns accelerations and related matters. Part 3 is devoted to the issues concerning temperature with the emphasis on joint statistics of temperature and velocity derivatives.
On the periodically excited plane turbulent mixing layer, emanating from a jagged partition
Authors: KIT E. , WYGNANSKI I. , FRIEDMAN D. , KRIVONOSOVA O. , ZHILENKO D. 
Published: March 2008

The flow in a turbulent mixing layer resulting from two parallel different velocity streams, that were brought together downstream of a jagged partition was investigated experimentally. The trailing edge of the partition had a short triangular ‘chevron’ shape that could also oscillate up and down at a prescribed frequency, because it was hinged to the stationary part of the partition to form a flap (fliperon). The results obtained from this excitation were compared to the traditional results obtained by oscillating a two-dimensional fliperon. Detailed measurements of the mean flow and the coherent structures, in the periodically excited and spatially developing mixing layer, and its random constituents were carried out using hot-wire anemometry and stereo particle image velocimetry.The prescribed spanwise wavelength of the chevron trailing edge generated coherent streamwise vortices while the periodic oscillation of this fliperon locked in-phase the large spanwise Kelvin–Helmholtz (K-H) rolls, therefore enabling the study of the inter- action between the two. The two-dimensional periodic excitation increases the strength of the spanwise rolls by increasing their size and their circulation, which depends on the input amplitude and frequency. The streamwise vortices generated by the jagged trailing edge distort and bend the primary K-H rolls. The present investigation endeavours to study the distortions of each mode as a consequence of their mutual interaction. Even the mean flow provides evidence for the local bulging of the large spanwise rolls because the integral width (the momentum thickness, θ), undulates along the span. The lateral location of the centre of the ensuing mixing layer (the location where the mean velocity is the arithmetic average of the two streams,y0), also suggests that these vortices are bent. Phase-locked and ensemble-averaged measurements provide more detailed information about the bending and bulging of the large eddies that ensue downstream of the oscillating chevron fliperon. The experiments were carried out at low speeds, but at sufficiently high Reynolds number to ensure naturally turbulent flow.
Are cascading flows stable?
Authors: THORPE S. A. , OZEN B. 
Published: March 2008

The stability of flows cascading down slopes as dense inclined plumes is examined, with particular reference to flows observed in Lake Geneva during winter periods of severe cooling. A previous conjecture by Turner that the flow may be in a state of marginal stability is confirmed: the observed mean velocity and density profiles are unstable to Kelvin–Helmholtz instability, but only marginally so; the growth rates of the most unstable small disturbances to the cascading flow in Lake Geneva are small, with e-folding periods of about 2 h. A reduction in the maximum velocity by about 20% is required to stabilize the flow.The possibility that stationary hydraulic jumps may occur in the observed flow is also considered. Several plausible flow states downstream of transitions are examined, allowing for mixing and density changes to occur, ranging from one that preserves the shape of the density and velocity profiles to one in which, as a consequence of mixing, the velocity and density become uniform in depth within the cascading flow. Neither of these extreme states is found to conserve the fluxes of volume, mass and momentum through a transition in which the energy flux does not increase, and to be unique or ‘stable’ in the sense that no further transition is possible to a similar flow state without more entrainment. Stable transitions to intermediate downstream flows that conserve flow properties and reduce energy flux are, however, found, although the smallest value of the flow parameter, Fr≡ Umax2/gΔ h (where Umax is the maximum flow speed, g is the acceleration due to gravity, Δ is a fractional density difference within the flow and h is the flow thickness) at which transitions may occur is only slightly less than that of the cascading flow in Lake Geneva. In this sense, the observed flow is marginally unstable to a finite-amplitude transition or hydraulic jump. Velocity and density profiles of possible flows downstream of a transition are found. The amplitudes of possible transitions and the flux of water entrained from the ambient overlying water mass are limited to narrow ranges.
Spectroscopic studies of Ca plasma generated by the fundamental, second, and third harmonics of a Nd:YAG laser
Authors: Hafeez S. , Shaikh N. M. , Baig M. A. 
Published: March 2008

AbstractThe ablation of calcium sample has been studied by the optical emission spectroscopy of the evolving plasma using the fundamental, second, and third harmonic of a Nd:YAG laser, which reveals numerous transitions due to neutral and singly ionized calcium. The measurements have been performed to determine the electron temperature and electron number density and their spatial behavior. In addition, the behavior of the electron temperature and number density as a function of laser irradiance and ambient gas pressure has been studied. The processes of laser photon absorption in the plasma through inverse bremsstrahlung and photoionization have also been discussed.