bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of phase transition in new ferroelectric 2‐aminopyridine phosphate crystal
Authors: Hek A. , Dacko S. , Czapla Z. , Cach R. 
Published: December 2003

AbstractThe dielectric properties of 2‐APP, a new ferroelectric crystal, were investigated around the ferroelectric phase transition at 103.5 K. The temperature dependence of electric permittivity was measured at dc electric fields up to 1000 kV/m. The electric permittivity was also measured in the paraelectric phase at constant temperature as a function of electric field intensity up to 150 kV/m. The results are discussed in the framework of the classical dielectric state equation and expansion coefficients A, B and C were estimated. It is found that the phase transition is of second order. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two mechanisms of 1D2 fluorescence quenching of Pr3+‐doped Y2SiO5 crystal
Authors: Malyukin Yu. V. , Masalov A. A. , Zhmurin P. N. , Znamenskii N. V. , Petrenko E. A. , Yukina T. G. 
Published: December 2003

AbstractIn Y2SiO5:Pr3+ crystals (0.1 at%, 0.3 at%, 0.6 at% , and 1.8 at% Pr3+) characterized by the existence of two types of Pr3+ optical centers, the energy transfer has been investigated using time‐resolved site‐selective spectroscopy techniques. The results obtained show that at certain conditions there are two different mechanisms of fluorescence quenching of the excited 1D2 states of Pr3+ ions. At 0.3 at% Pr3+ and under the excitation of 1D2 states as the result of 3P0 → 1D2 nonradiative relaxation, the phonon‐assisted energy transfer from 1D2 states of the I‐type Pr3+ ions to the II‐type ones has been found. The nonexponential part of donor fluorescence decay was described by the law t0.5. and the transfer efficiency exhibits a strong temperature dependence in the range of 1.5–80 K. At the direct selective excitation of the 1D2 states of one type Pr3+ optical centers it was possible to observe only their own fluorescence which quenched at a concentration above 0.6 at% Pr3+. The donor fluorescence decay was not fit by the law t0.5 and the quenching efficiency was characterized by the square‐loaw dependence on the concentration and a very poor dependency on the temperature. The analysis of some models allows us to assume, that in this case, the cooperative quenching of the 1D2 states of both type Pr3+ optical centers can take place. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hartree and exchange effects in the calculation of hole levels in p‐type delta‐doped diamond systems [phys. stat. sol. (b) 234, No. 2, 481 (2002)]
Authors: Mora‐Ramos M. E. 
Published: December 2003

AbstractCorrected values for the previously reported hole states in B δ‐doped diamond quantum wells are presented. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simplified bond‐hyperpolarizability model of second‐ and fourth‐harmonic generation: application to Si–SiO2 interfaces
Authors: Aspnes D. E. , Hansen J.‐K. , Peng H.‐J. , Powell G. D. , Wang J.‐F. T. 
Published: December 2003

AbstractWe recently developed a simplified bond‐hyperpolarizability model (SBHM) to describe the variation of second‐ and fourth‐harmonic‐generation (SHG, FHG) intensities as a function of sample azimuth angle, and applied it to various Si‐dielectric interfaces. The approach provides an efficient representation of these data with fewer parameters than required by Fourier or tensorial representations. In addition, these parameters have a direct physical meaning in microscopic terms. The model is simple enough to allow analytic expressions to be obtained for SHG and FHG intensities for (001) and (111) interfaces. SHG absorption is shown to result in easily recognized features in anisotropy data. Relative amplitudes of FHG intensities of the (001)Si–SiO2 interface among the three nonvanishing polarization combinations are shown to be consistent to a factor of about 2. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical reflectance of a composite medium with a sparse concentration of large spherical inclusions
Authors: García‐Valenzuela A. , Barrera R. G. 
Published: December 2003

AbstractWe analyze the coherent reflection of a half‐space of a composite material consisting of an homogeneous matrix with spherical inclusions. We pay attention to the case where the radius of the particles is comparable to the wavelength of the incident radiation. We consider a simple model for the interface of the composite and present numerical calculations to illustrate the contribution of the embedded particles to the optical reflectance and discuss surface effects. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strain induced optical anisotropies in zincblende semiconductors
Authors: Lastras‐Martínez L. F. , Balderas‐Navarro R. E. , Chavira‐Rodríguez M. , Flores‐Camacho J. M. , Lastras‐Martínez A. 
Published: December 2003

AbstractReflectance Difference (RD/RAS) spectroscopy has emerged in the last two decades as a sensitive probe for the study of surface and surface‐induced phenomena in zincblende semiconductors. This spectroscopy measures the difference in reflectivity between two mutually orthogonal polarizations and it is thus specific to semiconductor regions with symmetries lower than cubic. Photoreflectance‐difference (PRD) spectroscopy is a technique closely related to RD spectroscopy that measures the difference between two photoreflectance spectra, one with linearly‐polarized light and the other with non‐polarized light. In contrast to RD spectroscopy, PRD spectroscopy is specific to reflectance anisotropies of electro‐optic origin. In this paper we will discuss the application of both RD and PRD spectroscopies to the study of strain‐induced optical anisotropies in zincblende semiconductors. We will present a theoretical line shape model for both RD and PRD spectra that describes with high accuracy the experimental spectra. Results show the high sensitivity of these techniques for the study of piezo‐optical properties of zincblende semiconductors. Furthermore, results to be discussed should prove to be useful in the identification of strain‐induced contributions to RD spectra that are know to comprise components with a number of physical origins. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Second harmonic generation from a collection of nanoparticles
Authors: Brudny Vera L. , Mochán W. L. , Maytorena Jesús A. , Mendoza Bernardo S. 
Published: December 2003

AbstractIn this paper we discuss the SH radiation produced by a composite film made up of nanosized spherical centrosymmetric homogeneous particles. Although each individual sphere is unable to radiate in the forward direction when illuminated by a plane wave, our results show that for a thin composite film illuminated by a focused gaussian linearly polarized beam the radiation pattern presents two narrow lobes displaced along the polarization direction by a small angle of the order of the diffraction‐induced angular divergence of the linear far field. The SH radiation produced by a non‐homogeneous film, on the other hand presents non‐trivial patterns which depend on the fundamental frequency, the waist of the illuminating beam, the sharpness of the edge, the density profile and both the incoming and outgoing polarizations. We hope that these results can be extended to develop characterization techniques for composite films based on surface SHG or SFG. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Depth resolved nonlinear optical nanoscopy
Authors: Luis Mochán W. , López‐Bastidas Catalina , Maytorena Jesús A. , Mendoza Bernardo S. , Brudny Vera L. 
Published: December 2003

AbstractAn electromagnetic field forced to vary along a plane with a spatial scaledmuch smaller than its free space wavelengthλdecays exponentially along its normal with a decay length ∼d. This decay, similar to that of the wavefunction of tunneling electrons, has allowed the development of scanning near‐field optical microscopes (SNOMs), reminiscent of scanning tunneling and atomic force microscopes, which have been able to resolve structures in the nanometer scale. However, existing SNOMs are unable to determine the depth below the surface from which the optical signals arise due to the monotonic decay of the optical evanescent probe fields. In this paper we study the optical second harmonic generation (SHG) produced by mixing of the evanescent fields produced by a SNOM tip. We show that employing an appropriately spatially‐patterned tip, a non‐monotonic non‐linear probing field may be produced which has a maximum at a given distance beyond the tip, yielding a novel microscopy which may attain depth resolution with nanometric lengthscales. We estimate the size of the optical signal and we compare it with that arising in the usual SHG‐based surface spectroscopy of centrosymmetric materials. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin/carrier dynamics at semiconductor interfaces using intense, tunable, ultra‐fast lasers
Authors: Jiang Y. , Pasternak R. , Marka Z. , Shirokaya Y. V. , Miller J. K. , Rashkeev S. N. , Glinka Yu. D. , Perakis I. E. , Roy P. K. , Kozub J. , Choi B. K. , Fleetwood D. M. , Schrimpf R. D. , Liu X. , Sasaki Y. , Furdyna J. K. , Tolk N. H. 
Published: December 2003

AbstractWe review recent advances in spin/carrier dynamics at semiconductor interfaces using intense, tunable, ultrafast lasers, involving (a) carrier dynamics at Si/SiO2 interfaces with different oxide thicknesses, (b) radiation enhanced electron transport in ultra‐thin oxides, and (c) ultrafast spin dynamics in semiconductor heterostructures, probed by second‐harmonic generation (SHG). (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of spin–orbit interaction on cyclotron resonance in InAs quantum wells
Authors: Vasilyev Yu. B. , Suchalkin S. D. , Ivanov S. V. , Meltser B. Ya. , Kop'ev P. S. 
Published: December 2003

AbstractWe present the study of cyclotron resonance (CR) in a two‐dimensional electron gas in AlSb/InAs/AlSb quantum wells. The CR splitting, resolved at magnetic fields as low as 1.6 T, is found to be independent of the filling factor. We identify the origin of the splitting as related to the spin–orbit interaction. Spin–orbit coupling constants of 1.9 × 10–9 eV cm and 2.8 × 10–9 eV cm are obtained for samples with different band‐edge profiles. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
“Unconventional covalent” KAgF3 is metallic above 50 K
Authors: Grochala W. , Edwards P. P. 
Published: December 2003

AbstractUsing microwave cavity perturbation and magnetic susceptibility measurements we demonstrate for the first time that for KAgF3 the antiferromagnet–paramagnet transition leads to metallic state above 50 K. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Shape transition of medium‐sized neutral silicon clusters
Authors: Sieck A. , Frauenheim Th. , Jackson K. A. 
Published: December 2003

AbstractThe cover picture of this issue shows three Si71 cluster isomers, whose shape transition was addressed theoretically in Ref. [1]. The upper figure is a spherical fragment of the silicon crystal. Relaxation of this structure to the closest local energy minimum by the conjugate gradient method yields the cluster depicted in the centre. Only the outer atoms have been rearranged. Treating the initial structure with Simulated Annealing unveils a much more energetically favourable structure, as illustrated on the bottom.
Vakuum‐Drehdurchführungen mit Magnetflüssigkeitsdichtungen. Magnetic‐liquid‐sealed vacuum rotary feedthrough
Authors: Ochoński W. 
Published: December 2003

AbstractDrehdurchführungen mit Magnetflüssigkeitsdichtungen gewährleisten die höchste Reinheit im Vakuum. Das Dichtelement ist eine magnetisierbare Flüssigkeit, die mit einem Magnetfeld an der Dichtstelle gehalten wird. Diese Drehdurchführungen besitzen gegenüber konventionellen Dichtungsausführungen einzigartige Vorteile:‐ hermetische Dichtheit,‐ partikelfreier Betrieb, was in Vakuumprozessen höchste Reinheit sicherstellt,‐ keinerlei Haftreibung und günstiges Drehmomentübertragungsverhalten,‐ Tauglichkeit für extrem hohe Drehzahlen,‐ hohe Zuverlässigkeit und lange Lebensdauer.
Großflächenbeschichtung mit superhartem Kohlenstoff. Large area deposition of superhard carbon films
Authors: Stucky Thomas , Baier Urs , Meyer Carl‐Friedrich , Scheibe Hans‐Joachim , Schultrich Bernd 
Published: December 2003

AbstractIn den neunziger Jahren wurde am Fraunhofer‐Institut für Werkstoff‐ und Strahltechnik die Laser‐Arc‐Technologie zur Abscheidung wasserstofffreier, amorpher Kohlenstoffschichten hoher Härte (Diamor®) entwickelt. Nach der Optimierung und erfolgreichen Erprobung der bisher auf Laboranlagen hergestellten Diamor‐Schichten wurde die Technologie jetzt in ein Beschichtungsmodul zur industriellen Großflächenbeschichtung umgesetzt und die Quelle damit um einen Faktor 4 hochskaliert. Dieses Modul mit einer Beschichtungslänge von über einem Meter wurde angepasst an eine handelsübliche PVD‐Großanlage. Erste Ergebnisse zeigen, dass mit dieser Anlage größere Bauteile und Werkzeuge haftfest mit über 2 μm dicken Diamorschichten mit einer Härte oberhalb 4000 HV beschichtet werden können. Damit ist ein großer Schritt in Richtung der großindustriellen Anwendung der superharten Kohlenstoffschichten gelungen. Gleichzeitig demonstriert die im Dortmunder OberflächenCentrum installierte Anlage die Möglichkeit einer Aufrüstung von PVD‐Standard‐Anlagen mit der Laser‐Arc‐Technologie zur Abscheidung von Diamor®‐Schichten.
OVPD und Anwendung optischer Spektroskopiemethoden zur Wachstumskontrolle. OVPD and Applications of Optical Spectroscopic Methods to Growth Control
Authors: Zahn D.R.T. , Himcinschi C. , Friedrich M. , Paraian A. , Heuken M. 
Published: December 2003

AbstractOrganische Gasphasendeposition (OVPD) ist eine neue Wachstumstechnik, die für das Aufwachsen von dünnen Schichten auf großen Substratoberflächen bestens geeignet ist. Die polarisationsempfindlichen Messmethoden Ellipsometrie und Reflektionsanisotropie‐Spektroskopie (RAS), haben ein großes Potenzial zur Wachstumskontrolle im OVPD‐Prozess. Die Ellipsometrie ist sehr leistungsfähig, um die Dicke und die optischen Konstanten für OVPD‐Schichten zu bestimmen. Dies wurde für eine Alq3‐Schicht gezeigt. RAS ist eine ausgezeichnete Methode für die Detektion von sehr dünnen organischen Schichten, wie anhand einer PTCDA‐Schicht erläutert wird.
Nanotechnology – Markets & Trends. Nanotechnologie – Märkte und Trends
Authors: Köhler Thomas , Mietke Stephan , Ilgner Jürgen , Werner Matthias 
Published: December 2003

AbstractDurch vielversprechende Produkt‐ und Verfahrensinnovationen hat die Nanotechnologie in zunehmendem Maße sowohl das Interesse der Wissenschaft als auch das kommerzieller Nutzer geweckt. Diese Technologie mit ihren Möglichkeiten, im Maßstabsbereich unter 100 nm völlig neue funktionale Strukturen zu schaffen, hat in den letzten Jahren einen extremen Entwicklungsschub erfahren. Die große Bandbreite dieser neuen Eigenschaften erlaubt den Einsatz in einer Vielzahl neuer und verbesserter Applikationen und unterstreicht damit, dass die Nanotechnologie eine Schlüsseltechnologie des 21. Jahrhunderts ist. Nanotechnologie stellt nicht nur eine wissenschaftliche Herausforderung dar, vielmehr bildet sie bereits mit einer zunehmenden Zahl von innovativen Produkten die Grundlage für einen auch kommerziell hochinteressanten milliardenschweren Markt.
Pain management in elderly persons who require assistance with activities of daily living: a comparison of those living at home with those in special accommodations
Authors: Jakobsson Ulf , Hallberg Ingalill Rahm , Westergren Albert 
Published: December 2003

AbstractObjectives: To describe and compare the methods of pain management used by elderly individuals with chronic pain and requiring assistance with activities of daily living, depending on whether they live alone, with someone, at home or in special accommodations.Methods: This study comprised 294 people aged 76–100 years, identified as having chronic pain and requiring assistance with activities of daily living. Pain and pain management methods were compared using the Multidimensional Pain Inventory, Swedish version, and the Pain Management Inventory.Results: Those living in special accommodations reported more pain than those living at home. Those living with someone reported more pain and interference in daily life than those living alone, despite using more pain‐relief methods and having greater social support. The median number of pain‐relieving methods used was 3.0 (75th‐25th percentile: 5–2). Some (3.8%) did not use any method to relieve their pain. The most frequently used methods were prescribed medicine (20%), rest (20%) and distraction (15%). The methods rated most effective were using cold, exercise, hot bath/shower and consuming alcohol.Conclusion: Participants had only a small repertoire of pain management methods and these were mostly conventional in nature. Few non‐pharmacological methods were used. The findings suggest the importance of thorough assessment, and the need to fully discuss pain management options with the elderly.
Intrathecal baclofen as adjuvant therapy to enhance the effect of spinal cord stimulation in neuropathic pain: a pilot study
Authors: Lind Göran , Meyerson Björn A , Winter Jaleh , Linderoth Bengt 
Published: December 2003

AbstractOnly about 60–70% of well selected patients with neuropathic pain syndromes of peripheral origin enjoy sufficient pain relief with spinal cord stimulation (SCS). Since recent animal experiments have demonstrated that the GABA‐B receptor is pivotal in the effect of SCS on certain neuropathic symptoms, the use of baclofen as an adjunct to stimulation emerged as an option in patients not responding satisfactorily to SCS. Forty‐eight patients with neuropathic pain of peripheral origin responding poorly to SCS were enrolled in a study with intrathecal baclofen; in a few cases adenosine was also tried. Twenty patients reported significant pain reduction at bolus trials and were offered implantation of a drug pump. Seven patients subsequently had pumps implanted together with SCS and four had pumps alone. Three patients had only peroral baclofen therapy as an adjunct to SCS. The 14 patients continuing with baclofen therapy as an adjunct to SCS, or alone, were followed for an average of 35 months after pump implant. The group with SCS + pump (n=5; 2 explanted) reported an average decrease of pain ratings from VAS 82 to 33. The group with i.t. baclofen only had a pain decrease from VAS 63 to 33, while the three patients with peroral baclofen + SCS had less benefit from drug therapy. Adjunctive drug therapy for patients with unsatisfactory pain relief by SCS may offer a possibility to enhance pain alleviation.
Returning the chronically unemployed with low back pain to employment
Authors: Watson Paul J , Booker C. Kerry , Moores Lorraine , Main Chris J 
Published: December 2003

AbstractMuch of the research into return to work following rehabilitation for low back pain in the literature reflects work done in those employed. Unemployment is a consequence of chronic low back pain which has considerable health and economic consequences for the individual and society. This paper describes an occupationally orientated rehabilitation programme for long‐term unemployed people (mean duration of unemployment 38.9 months). The aim of the project was to identify factors which predict return to work and progress towards employment. Eight six subjects underwent a pain management rehabilitation programme incorporating vocational focussing and advice, subjects were followed up at 6 months to determine work status. At follow‐up 38.4% of subjects were employed and another 23% were in voluntary work, or education/training. There were no significant differences on presenting characteristics between those who returned to work and those who did not. Subjects were divided into those who made positive progress (work, education/training or voluntary work) and those who did not (remained unemployed, dropped out of the programme or lost to follow up). Those who failed to make positive progress were characterised by longer duration of unemployment and higher scores on somatic anxiety and depression. A predictive model was able to identify 80% of those who failed to make progress but prediction of those achieving a positive outcome was poor (44% correct prediction). The factors predicting return to work in unemployed people with low back pain differs from the employed, the need for employment skills training and a vocational focus to rehabilitation are highlighted.
Ibuprofen inhibition of tendon cell proliferation and upregulation of the cyclin kinase inhibitor p21CIP1
Authors: Tsai Wen‐Chung , Tang Fuk‐Tan , Hsu Chih‐Chin , Hsu Yai‐Hui , Pang Jong‐Hwei S. , Shiue Chian‐Chuan 
Published: December 2003

AbstractSports‐related tendon injuries are commonly treated with nonsteroidal antiinflammatory drugs. This study was designed to determine the in vitro effect of ibuprofen on the proliferation of tendon cells intrinsic to rat Achilles tendon. Furthermore, the existence of a correlation between this effect and the expression of the cyclin kinase inhibitor p21CIP1 and retinoblastoma (Rb) protein was also examined. Using cultured tendon cells, cell viability was evaluated by MTT assay. To determine whether apoptosis was related to the effect of ibuprofen, terminal deoxynucleotidyl transferase nick‐end labeling (TUNEL) assay was used. The mitotic index (MI) was calculated from the number of cells in the mitotic phase as stained and identified by propidium iodide. The mRNA expression of p21CIP1 was determined by reverse transcription‐polymerase chain reaction (RT‐PCR). Protein expressions of p21CIP1 and Rb protein were determined by Western blot analysis. A dose‐dependent decrease in the cellularity of tendon cells by ibuprofen was demonstrated by MTT assay (p < 0.001). However, TUNEL assay revealed no evidence of apoptosis. Ibuprofen dose‐dependently reduced the MI (p < 0.001). Upregulation of p21CIP1 both at the levels of mRNA expression and protein was revealed from RT‐PCR and Western blot analyses. The inhibition of Rb protein phosphorylation was also noted in ibuprofen‐treated cells. In conclusion, ibuprofen inhibits tendon cell proliferation in a process that is probably mediated by the upregulation of p21CIP1 and reduced phosphorylation of Rb protein. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.