bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser and Microwave Welding – The Applicability of New Process Principles
Authors: Potente Helmut , Karger Odo , Fiegler Georg 
Published: December 2002

AbstractThis article has been compiled on the basis of the many years' experience that has been acquired in the field of plastics welding by the Institute of Plastics Engineering (KTP) at the University of Paderborn. A brief report is given on the state of the art in laser and microwave welding technology. An overview is also included on the potential and limits of the use of laser and microwave welding in plastics processing. In the case of laser welding, a number of results achieved in welding of molded parts are presented that have been obtained in the course of extensive investigations. For microwave welding, a report is included on investigations that are currently running at the KTP. In addition to this, details are given on the basic suitability of laser and microwave welding for joining films and sheetings.
Configuration for the indirect microwave welding of panels, left: side view, right: cross‐section.magnified imageConfiguration for the indirect microwave welding of panels, left: side view, right: cross‐section.
An Approach to Calculating Wear on Annular Non‐Return Valves
Authors: Potente Helmut , Többen Wilhelm H. , Kaiser Elmar 
Published: December 2002

AbstractThe serviceability of non‐return valves has a major influence on the productivity of the injection molding process. During a meeting of experts held at our Institute, it was seen that closing behavior and wear are the key problems encountered in practice. The conducted investigations to tackle these questions have shown that both an improved closing behavior and a lower level of wear can be achieved by reducing the inside radius of the locking ring.
Pressure profile over the length of a non‐return valve (n = 0.4; ${\rm \dot V}$ = 25 000 mm3/s).magnified imagePressure profile over the length of a non‐return valve (n = 0.4; ${\rm \dot V}$ = 25 000 mm3/s).
Process Description for the Extrusion of Rubber Compounds – Development and Evaluation of a Screw Design Software
Authors: Limper Andreas , Schramm Dominik 
Published: December 2002

AbstractThe development of a mathematical model to be used in a simulation software for the description of rubber extrusion operating points is presented. A discrete model for the flow has been introduced, which considers the flow in the main direction and in the cross section of the screw channel. Moreover the flow model is connected with a discrete model for the computation of the temperature within the screw channel, an FDM approach has been used here. The combination permits the non‐isothermal flow simulation along extruder screws. Beside the isothermal and non‐isothermal option the simulation software, obtained on the basis of the models described, allows a multi‐variation of parameters as well. It is shown how such a variation mode can be used within a screw geometry optimization process and a short comparison of simulated and experimental data for the optimized concept is given. Further examples of comparison simulation/experiment are demonstrating that results can prone to error. The occuring lack of the model is most likely linked to an insufficient description of the rheology of rubber compounds. Further imperfection discussed are the processes within the feeding section. For example feed rolls and grooved barrels are often installed and effective for the process but not considered within theoretical models.
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Immunoglobulins against gp273, the ligand for sperm–egg interaction in the mollusc bivalve Unio elongatulus, are directed against charged O‐linked oligosaccharide chains bearing a Lewis‐like structure and interact with epitopes of the human zona pellucida
Authors: Focarelli Riccardo , Capone Antonietta , Ermini Leonardo , Del Buono Francesca , Battista La Sala Giovanni , Balasini Marcella , Rosati Floriana 
Published: December 2002

AbstractIn oocytes of the mollusc bivalve Unio elongatulus, gp273 is the ligand molecule for sperm–egg interaction and binding is mediated by its O‐glycans. A serum raised against this protein enabled its localization in the crater region, the area of the vitelline coat where sperm recognition occurs, and showed that after cyanogen bromide fragmentation, the anti‐gp273 epitope(s) was retained by a peptide where the O‐glycans are localized. In this article, we utilized purified anti‐gp273 immunoglobulins to characterize the corresponding epitope by: (i) immunoblotting analysis of the protein after removal of O‐ and N‐glycans; (ii) solid phase binding analysis of anti‐gp273 IgG to gp273 N‐ and O‐glycans; and (iii) binding analysis of the same antibody to commercially available oligosaccharides. The results showed that the epitope consists of O‐glycans and contains a Lewis‐like structure with fucose as determinant. Anti‐gp273 IgG were then used to investigate human zona pellucida by immunoelectronmicroscopy and immunoblotting. Epitopes recognized by the antibody were demonstrated on the outer surface of the zona pellucida and shown to belong to a zona pellucida protein having electrophoretic mobility similar to human ZP3. Since human sperm specifically bind to gp273, and anti‐gp273 interferes with this binding a functional role for these epitopes is suggested. Mol. Reprod. Dev. 64: 226–234, 2003. © 2003 Wiley‐Liss, Inc.
Changes of messenger RNAs encoding vascular endothelial growth factor and its receptors during the development and maintenance of caprine corpora lutea
Authors: Kawate Noritoshi , Tsuji Makoto , Tamada Hiromichi , Inaba Toshio , Sawada Tsutomu 
Published: December 2002

AbstractThe present study was conducted to examine changes of mRNAs encoding vascular endothelial growth factor (VEGF) and its receptors (KDR/Flk‐1 and Flt‐1), and CD34, which is known to be a specific marker for endothelial cells, during the development and maintenance of the caprine corpora lutea (CL). Effects of a potent GnRH antagonist (GA), which was previously shown to suppress release of luteinizing hormone (LH), on expressions of those mRNAs during the CL development were also investigated. Goats were divided into control (n = 12) and GA‐treated groups (n = 6). The goats were treated with saline or GA (50 μg/kg, sc) on days 0 (day of ovulation), 4, and 8 (control only), and CL collected on a subset of goats (n = 3 for each day) on days 0 (no saline), 4, 8, or 14 (control only). Ribonuclease protection assay was performed to quantitate the mRNAs in the CL using specific cRNA probes generated by RT‐PCR and in vitro transcription. Level of CD34 mRNA significantly increased from day 0 to 8 (CL development) in the control group (P < 0.05). Long and short forms were detected in the caprine CL by RT‐PCR for VEGF mRNA and analyses of their sequences showed that they correspond to mRNAs encoding VEGF165 and VEGF121, respectively. Level of VEGF165 mRNA significantly increased from day 4 to 8 and day 8 to 14 (CL maintenance) in the control group (P < 0.05) while VEGF121 mRNA did not change during the whole period. Level of KDR/Flk‐1 mRNA significantly increased from day 0 to 8 (P < 0.05) while Flt‐1 mRNA significantly increased from day 8 to 14 (P < 0.005) in the control group. In the GA‐treated group, levels of all of the mRNAs did not alter remarkably as compared with those in the control group. These results suggest that rise of KDR/Flk‐1 and VEGF165 mRNAs during the caprine CL development may be associated with enhanced angiogenesis and that increment of VEGF165 and Flt‐1 mRNAs during the CL maintenance may play nonangiogenic roles. The present study also indicates that the changes of VEGF165 and KDR/Flk‐1 mRNAs during the CL development are probably not regulated by LH. Mol. Reprod. Dev. 64: 166–171, 2003. © 2003 Wiley‐Liss, Inc.
Resumption of metabolic activity of vitrified/warmed ovine embryos
Authors: Leoni Giovanni , Berlinguer Fiammetta , Rosati Irma , Bogliolo Luisa , Ledda Sergio , Naitana Salvatore 
Published: December 2002

AbstractTo evaluate resumption of metabolic activity of vitrified ovine embryos during a short time immediately after warming, blastocysts collected from superovulated Sarda ewes were incubated with 35S‐methionine. In vitrified/warmed embryo groups the protein secretion significantly (P < 0.05) increased from 0 to 24 hr of culture, reaching significantly (P < 0.01) higher activity at 18–24 hr and dropping to values similar to the control nonvitrified embryo group at 29–35 hr. Within the control group at 29–35 hr there was a significantly (P < 0.01) higher level of protein secretion compared to the other interval times. The electrophoretic pattern showed a 48–50 kDa secreted protein identified as urokinase‐type plasminogen activator (PA). The caseinolytic assay of PA activity showed a course similar to protein secretion in both vitrified and control groups. During 29–35 hr of culture, we did not observe any improvement in PA activity as seen for secreted proteins. At this time, we observed the secretion of a new 20 kDa protein that was not present in vitrified/warmed embryos. Analysis of BrDU incorporation in newly synthesised DNA showed a significant (P < 0.01) improvement in positive cell number from 3 to 9 hr after warming, reaching a value similar to that of the control group at 12 hr of culture. Our results suggest that vitrified/warmed embryos require 9–12 hr of culture to complete resumption of DNA synthesis and 29–35 hr to re‐acquire the full capacity of protein secretion but not the qualitative secretion pattern. Mol. Reprod. Dev. 64: 207–213, 2003. © 2003 Wiley‐Liss, Inc.
Evidence for the Hypothesis of Ignition of Propellants by Metallic Vapour Deposition
Authors: Taylor Michael J. 
Published: December 2002

AbstractThis paper examines the experimental evidence to support the hypothesis of ignition of energetic material by the process of metallic vapour deposition. The hypothesis has been presented previously, and this is the continuation of the work. The hypothesis has been developed at QinetiQ to explain certain measurements of incident radiative flux during electrothermal‐chemical (ETC) experimentation, which show no correlation with the ignition event. Indeed, measured levels of radiation have been so low that radiative energy transfer for ETC plasma ignition could be said to be negligible. Measurement of the thickness of a metal layer resulting from dropwise vapour condensation gives good correlation to the flux requirements for ignition.
Characterization of Aluminum Powders I. Parameters of Reactivity of Aluminum Powders
Authors: Ilyin Alexander , Gromov Alexander , An Vladimir , Faubert François , de Izarra Charles , Espagnacq André , Brunet Luc 
Published: December 2002

AbstractFor testing the determination of the reactivity of aluminum powders it is proposed to use the following parameters: temperature of the beginning of oxidation, maximal oxidation rate, degree of transformation (degree of oxidation) of aluminum, relative thermal effect. Parameters for an evaluation of the reactivity of powders were chosen following the analysis of results of a non‐isothermal oxidation of powders of different grain size under conditions of programmed heating (the oxidizer being air). According to the proposed method of testing, the sample of ultrafine powder UFAP‐4 produced by the electrical explosion of wires has the highest reactivity among the studied powders.
Electronic properties of Si/SiGe ultrathin quantum well superlattices
Authors: Rached D. , Benkhettou N. , Sekkal N. 
Published: December 2002

AbstractUsing the self‐consistent and perturbative method of Jaros and the full potential linear muffin tin orbitals (FP‐LMTO) method coupled to a plane wave (PLW) basis in the interstitial regions, we calculate the bandstructure of some ultrathin Sim/(SiGe)n quantum well superlattices, m and n being the numbers of atomic layers. The results show that in these systems the bandgap is indirect and that these superlattices have a type II potential configuration.
DX behaviour of Si donors in AlGaN alloys
Authors: Brandt Martin S. , Zeisel Roland , Gönnenwein Sebastian T. B. , Bayerl Martin W. , Stutzmann Martin 
Published: December 2002

AbstractRecent experiments on the DX behaviour of Si in AlGaN alloys are reviewed. From persistent photoconductivity, light‐induced electron spin resonance, and thermal quenching experiments as well as from the thermal activation of the generation‐recombination noise, a quantitative configuration coordinate diagram is constructed for pure AlN and Al0.75Ga0.25N. The effects of DX centres on the properties of AlGaN alloys with lower Al concentration are discussed.
Resonant states in doped quantum wells
Authors: Blom A. , Odnoblyudov M.A. , Yassievich I.N. , Chao K.A. 
Published: December 2002

AbstractResonant states can have an important influence on the electronic transport, noise and optical properties of heterostructure devices. We have used a non‐variational method to study the resonant states formed by shallow donors inside and outside of quantum wells. The method allows us the evaluation of the position and the width (lifetime) of the resonant states and also of matrix elements such as optical transition probabilities. When the width is compared to results from the approach of resolvent operators, a quantitative difference is found, which we attribute to the neglected intraband scattering in the latter method. We also show how the impurity states, localized and resonant, evolve as the donor is moved into the quantum well from an originally infinite distance.
Optically pumped terahertz semiconductor bulk lasers
Authors: Pavlov S. G. , Hübers H.‐W. , Orlova E. E. , Zhukavin R. Kh. , Riemann H. , Nakata H. , Shastin V. N. 
Published: December 2002

AbstractThe principles of stimulated emission for the terahertz frequency range from shallow impurity centers in bulk semiconductors are discussed. Evidence of stimulated emission from group V donors embedded in silicon (P, Sb, Bi) as well as spontaneous emission from Li acceptor in monocrystalline ZnSe under excitation by CO2 laser radiation at low temperatures is demonstrated. The temporal behavior and the emission spectra of the lasers are presented.
THz lasing of SiGe/Si quantum‐well structures due to shallow acceptors
Authors: Kagan M. S. , Altukhov I. V. , Chirkova E. G. , Sinis V. P. , Troeger R. T. , Ray S. K. , Kolodzey J. 
Published: December 2002

AbstractAn intense THz emission was observed from strained SiGe/Si quantum‐well structures under strong pulsed electric field. The p‐type structures were MBE‐grown on n‐type Si substrates and δ‐doped with boron. Lines with wavelengths near 100 microns were observed in the emission spectrum. The modal structure in the spectrum gave evidence for the stimulated nature of the emission. The origin of the THz emission was attributed to intra‐centre optical transitions between resonant and localized boron levels.
Hydrogen as a shallow center in semiconductors and oxides
Authors: Van de Walle Chris G. 
Published: December 2002

AbstractWe describe the physics of interstitial hydrogen in semiconductors and oxides based on a first‐principles computational approach. In most semiconductors hydrogen acts as an amphoteric impurity, compensating the prevailing conductivity. In ZnO, however, hydrogen acts a shallow donor. We have developed a general model for the behavior of hydrogen in semiconductors and oxides, and confirmed its predictive nature in the case of InN and GaAsN alloys.
Nitrogen–hydrogen complexes in GaAs and GaAs1–xNx alloys
Authors: Kim Yong‐Sung , Chang K.J. 
Published: December 2002

AbstractWe investigate the atomic structure of various N–H complexes in GaAs and GaAs1–xNx alloys through first‐principles pseudopotential calculations within the local‐density‐functional approximation. For GaAs with low H concentrations, we suggest that nitrogen forms a N–H(BC) complex, where H is positioned at a bond‐center site between a substitutional N and one of the neighboring Ga atoms. For very high H concentrations, an optically inactive N–H2*(BC‐ABN) complex, which corresponds to a configuration of H2* in the vicinity of N, is suggested to be an energetically favorable structure. These atomic models explain many experimental features observed in GaAs and GaAs1–xNx alloys, which contain both N and H.
Donor centers in zinc germanium diphosphide produced by electron irradiation
Authors: Gehlhoff W. , Azamat D. , Hoffmann A. 
Published: December 2002

AbstractThe properties of defects in p‐type zinc germanium diphosphide (ZnGeP2) were studied by means of electron paramagnetic resonance (EPR) and photo‐EPR. Besides the well‐known three native defects (VZn, VP, GeZn) an S = 1/2 EPR spectrum is observed in electron‐irradiated ZnGeP2 with an isotropic g = 2.0123 and resolved hyperfine splitting from four equivalent I = 1/2 neighbors. This spectrum is caused by a new center generated by the electron‐irradiation and not by an existing center that is recharged as a result of the irradiation induced Fermi‐level shift. It is tentatively assigned to the isolated Ge vacancy. Observation of the photoinduced recharging processes demonstrates that the location of the level VGe3–/2– is at Eopt = (0.7 ± 0.06) eV. An annealing of the electron‐irradiated samples causes a reverse shift of the Fermi level in direction to its original position and is accompanied with a reduction of an isotropic unstructured line at g = 2.003 caused by the irradiation damage.
Coral mortality and recovery in response to increasing temperature in the southern Arabian Gulf
Authors: Sheppard Charles , Loughland Ronald 
Published: December 2002

Analysis of a new data set for sea surface temperature shows that the seawater temperature rise in 1998 in the southern Arabian Gulf was the largest since 1870; it also showed that there is an underlying rising trend of sea surface temperature across the whole of the measured area spanning 5 degrees longitude and 3 degrees latitude. Over the last 50 years, sea surface temperature rise was about 0.2°C per decade, though this has accelerated to about 0.45°C per decade in the last 20 years. The pattern in temperature values in each 1 degree ‘cell’ are used to show that, at any one time, temperature rises towards the east of this area, which supports the concept of a general anti-clockwise circulation in the southeastern half of the Arabian Gulf. Spatial and temporal patterns in sea surface temperature rises also show that the mean temperature field at any location is similar to that which existed in the one degree cell immediately to its east approximately 30 years earlier.Coral cover in shallow water (&lt;3 m depth) was &lt;1 percent immediately following the 1998 event, due to near total mortality of vast areas of shallow Acropora (stagshorn) corals. Deeper than 3 m there was increasing survival of the large Porites (boulder) corals, survival increasing with depth. Coral survival improved towards the east, though overall, less than twenty coral species were found altogether. Juvenile recruitment also increased towards the east, and at any one site, recruitment increased with increasing depth. The identity of new juveniles was mainly faviid corals, not the Acropora or Porites which dominated these reefs before the 1998 event. This suggests that there may be a phase shift to a different stable state in terms of coral communities. We also speculate that, because the Arabian Gulf contains an extreme warm-tolerant subset of the Indian Ocean coral fauna, the changes seen in the Gulf may reflect future patterns across a greater part of the Indian Ocean.
Analysis of the Compartmentation of Glycolytic Intermediates, Nucleotides, Sugars, Organic Acids, Amino Acids, and Sugar Alcohols in Potato Tubers Using a Nonaqueous Fractionation Method
Authors: Farré Eva M. , Tiessen Axel , Roessner Ute , Geigenberger Peter , Trethewey Richard N. , Willmitzer Lothar 
Published: December 2002

Abstract
The compartmentation of metabolism in heterotrophic plant tissues is poorly understood due to the lack of data on metabolite distributions and fluxes between subcellular organelles. The main reason for this is the lack of suitable experimental methods with which intracellular metabolism can be measured. Here, we describe a nonaqueous fractionation method that allows the subcellular distributions of metabolites in developing potato (Solanum tuberosum L. cv Desiree) tubers to be calculated. In addition, we have coupled this fractionation method to a recently described gas chromatography-mass spectrometry procedure that allows the measurement of a wide range of small metabolites. To calculate the subcellular metabolite concentrations, we have analyzed organelle volumes in growing potato tubers using electron microscopy. The relative volume distributions in tubers are very similar to the ones for source leaves. More than 60% of most sugars, sugar alcohols, organic acids, and amino acids were found in the vacuole, although the concentrations of these metabolites is often higher in the cytosol. Significant amounts of the substrates for starch biosynthesis, hexose phosphates, and ATP were found in the plastid. However, pyrophosphate was located almost exclusively in the cytosol. Calculation of the mass action ratios of sucrose synthase, UDP-glucose pyrophosphorylase, phosphoglucosisomerase, and phosphoglucomutase indicate that these enzymes are close to equilibrium in developing potato tubers. However, due to the low plastidic pyrophosphate concentration, the reaction catalyzed by ADP-glucose pyrophosphorylase was estimated to be far removed from equilibrium.
Theories of general personality and mental disorder
Authors: Duggan C. , Milton J. , Egan V. , McCarthy L. , Palmer B. , Lee A. 
Published: December 2002

BackgroundA major short coming of current research into personality is its failure to explore the relationship between theories of general personality and mental disorder.AimsTo provide preliminary data to address this deficit.MethodIn the first of two studies, we examined the relationship between the Neuroticism, Extraversion and Other – Five-Factor Inventory (NEO–FFI) and DSM personality disorders in a consecutive series of mentally disordered offenders. In the second, we sought to separate the personality dimension neuroticism from symptoms of depressive disorder in a sample of subjects with current depression.ResultsFactors from the NEO–FFI were associated with different personality disorders in a predictable manner (first study). It was possible to identify a component of neuroticism (i.e. ‘worry’) that could be separated from depressive symptoms (second study).ConclusionsTheories of general personality theory can enlighten and refine descriptions of abnormal mental states by informing both their aetiology and their prognosis.
Resonant Tunneling Processes along Conjugated Molecular Wires: A Quantum‐Chemical Description
Authors: Karzazi Y. , Cornil J. , Brédas J.‐L. 
Published: December 2002

AbstractMolecular electronics research is a very active area in the field of nanotechnology. It is now well established that individual or self‐assembled molecules can behave as nanoscopic switches in transistor and diode configurations. Molecular wires inserted into nanopores and contacted by two metallic electrodes can also be used as active elements for the fabrication of resonant tunneling diodes (RTDs). The RTD current/voltage (I/V) characteristics can display a negative differential resistance (NDR) behavior (i.e., a negative slope in the I/V curve) for reasons that are not yet fully understood. Here we describe a possible mechanism at the quantum‐chemical level that is based on conformational effects and accounts for the experimental observation of strong NDR signatures in substituted phenylene ethynylene oligomers. The occurrence of a peak current in the I/V curves is rationalized by analyzing the evolution of the one‐electron structure of the molecular wires upon application of a static electric field aligned along the molecular axis (the field simulates the driving voltage applied between the two electrodes in the RTD devices). The results of our calculations provide a general basis to develop strategies for the design of molecular wires displaying an NDR behavior.