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  • 1
    Digitale Medien
    Digitale Medien
    Modeling of plume dynamics in laser ablation processes for thin film deposition of materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 2203-2209 
    Details
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The transport dynamics of laser-ablated neutral/plasma plumes are of significant interest for film growth by pulsed-laser deposition of materials, since the magnitude and kinetic energy of the species arriving at the deposition substrate are key processing parameters. Dynamical calculations of plume propagation in vacuum and in background gas have been performed using particle-in-cell hydrodynamics, continuum gasdynamics, and scattering models. Results from these calculations are presented and compared with experimental observations. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.871676
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  • 2
    Digitale Medien
    Digitale Medien
    Reduced oxygen diffusion through beryllium doped platinum electrodes (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 1389-1391 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Using first principles electronic structure calculations we screen nine elements for their potential to retard oxygen diffusion through polycrystalline Pt (p-Pt) films. We determine that O diffuses preferentially as interstitial along Pt grain boundaries (GBs). The calculated barriers are compatible with experimental estimates. We find that Be controls O diffusion through p-Pt. Beryllium segregates to Pt GBs at interstitial (i) and substitutional (s) sites. i-Be is slightly less mobile than O and it repels O, thus stuffing the GB. s-Be has a high diffusion barrier and it forms strong bonds to O, trapping O in the GB. Experiments confirm our theoretical predictions. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.124703
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  • 3
    Digitale Medien
    Digitale Medien
    Defect generation and diffusion mechanisms in Al and Al–Cu (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 34-36 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A defect generation mechanism, namely, the grain-boundary Frenkel pair model, and corresponding diffusion mechanisms during electromigration are developed using atomic simulation techniques in Al and Al–Cu. We contend that large numbers of interstitials and vacancies exist at grain boundaries and both contribute to mass transport. Cu preferentially segregates to the interstitial sites at grain boundaries via a Frenkel pair generation process and reduces the overall grain-boundary diffusivity due to the stronger Al–Cu binding. Predictions from our models are in excellent agreement with available experimental data and observations. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.123124
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  • 4
    Digitale Medien
    Digitale Medien
    Environmental Isotope Characteristics of Landfill Leachates and Gases (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 34 (1996), S. 0 
    Details
    ISSN: 1745-6584
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Energietechnik , Geologie und Paläontologie
    Notizen: The isotopic characteristics of municipal landfill leachate and gases (carbon dioxide and methane) are unique relative to the aqueous and gaseous media in most other natural geologic environments. The δ13C of the CO2 in landfills is significantly enriched in 13C, with values as high as +20 ‰ reported. The δ13C and δD values of the methane fall within a range of values representative of microbial methane produced primarily by the acetate-fermentation process. The δD of landfill leachate is strongly enriched in deuterium, by approximately 30 ‰ to nearly 60 ‰ relative to local average precipitation values. This deuterium enrichment is undoubtedly due to the extensive production of microbial methane within the limited reservoir of a landfill. The concentration of the radiogenic isotopes, 14C and 3H, are significantly elevated in both landfill leachate and methane. The 14C values range between approximately 120 and 170 pMC and can be explained by the input of organic material that was affected by the increased 14C content of atmospheric CO2 caused by atmospheric testing of nuclear devices. The tritium measured in leachate, however, is often too high to be explained by previous atmospheric levels and must come from material buried within the landfill. The unique isotopic characteristics observed in landfill leachates and gases provide a very useful technique for confirming whether contamination is from a municipal landfill or some other local source.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1745-6584.1996.tb02077.x
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  • 5
    Digitale Medien
    Digitale Medien
    Intra-abdominal follicular dendritic cell tumour: a rare tumour in need of recognition (1998)
    Oxford, U.K. and Cambridge, USA : Blackwell Science Ltd
    Histopathology 33 (1998), S. 0 
    Details
    ISSN: 1365-2559
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Neoplasms of follicular dendritic cells are uncommon and the majority of them occur in lymph nodes. Rarely, they may occur inside the abdominal cavity. We describe two examples of intra-abdominal follicular dendritic cell (FDC) tumour. One involved the liver and the other involved the ampulla of Vater. Our aims are to complement the current understanding on this disease and to alert histopathologists and clinicians to this rare entity.〈section xml:id="abs1-2"〉〈title type="main"〉Materials and resultsThe clinical and radiological findings of the two cases of intra-abdominal follicular dendritic cell tumours were reviewed. The resected specimens were examined macroscopically and microscopically. Immunohistochemical studies, ultrastructural examination and in situ hybridization for Epstein–Barr virus were also performed. Both tumours could not be accurately diagnosed before pathological examination of the resected specimens. The soft to slightly firm consistency of the tumours resembled that of fixed brain tissue, and was distinctly different from hepatocellular carcinoma or pancreatic carcinoma. The fascicular arrangement of syncytial plump to spindle cells in a background of mixed inflammatory cells was the initial clue to the diagnosis, which was confirmed by the immunoreactivity of the tumour cells to follicular dendritic cell markers (CD21 and CD35), and by the demonstration of focal intercellular desmosome-like junctions between the complex cytoplasmic processes of the tumour cells. The tumour cells in the liver tumour also showed presence of Epstein–Barr virus on in situ hybridization study.〈section xml:id="abs1-3"〉〈title type="main"〉ConclusionsAwareness of the entity and the ability to recognize this tumour by histopathologists are emphasized because the tumour closely mimics a wide variety of other tumours and tumour-like lesions. Similar to the other reported FDC tumours of the liver, our case of hepatic follicular dendritic cell tumour is also positive for Epstein–Barr virus, suggesting that the virus may play a role in its pathogenensis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2559.1998.00547.x
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  • 6
    Digitale Medien
    Digitale Medien
    Optimal Graph Constraint Reduction for Symbolic Layout Compaction (1997)
    Springer
    Algorithmica 18 (1997), S. 560-574 
    Details
    ISSN: 1432-0541
    Schlagwort(e): Key words. VLSI layout, Compaction, Graph constraints, Constraint graphs, Constraint reduction, Transitive reduction, Difference constraints.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract. The compaction problem in VLSI layout can be formulated as a linear program. To reduce the execution time and memory usage in compaction, it is important to reduce the size of the linear program. Since most constraints in compaction are derived directly or indirectly from physical separation and electrical connectivity requirements which can be expressed in the form of graph constraints, we study the graph constraint reduction problem. That is the problem of producing, for a given system of graph constraints, an equivalent system with the fewest graph constraints. After observing that the problem as previously formulated is NP-hard and overrestrictive in that the maximum possible reduction is not always attainable, we propose a new formulation in which the maximum possible reduction is guaranteed. We further present a polynomial-time algorithm for the new formulation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/PL00009173
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  • 7
    Digitale Medien
    Digitale Medien
    Area minimization for hierarchical floorplans (1996)
    Springer
    Algorithmica 15 (1996), S. 550-571 
    Details
    ISSN: 1432-0541
    Schlagwort(e): Design automation ; VLSI layout ; Floorplanning ; Floorplan sizing ; Area minimization ; NP-complete ; Hierarchical floorplans ; Pseudopolynomial
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract In this paper we study the area-minimization problem for hierarchical floorplans. We settle an open problem on the complexity of the area-minimization problem for hierarchical floorplans by showing it to be NP-complete (even for balanced hierarchical floorplans). We then present a new algorithm for determining the nonredundant realizations of a wheel. The algorithm has time costO(k 2 logk) and space cost0(k 2) if each block in a wheel has at mostk realizations. Based on the new algorithm for a wheel, we design a new pseudopolynomial area-minimization algorithm for hierarchical floorplans of order-5. The time and space costs of the algorithm are0((nM)2log(nM) and0(n 2 M), respectively, wheren is the number of basic blocks andM is an upper bound on the dimensions of the realizations of the basic blocks. The area-minimization algorithm was implemented. Experimental results show that it is very fast.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01940881
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  • 8
    Digitale Medien
    Digitale Medien
    An integrated algorithm for incremental data path synthesis (1996)
    Springer
    The journal of VLSI signal processing systems for signal, image, and video technology 12 (1996), S. 265-285 
    Details
    ISSN: 1573-109X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this paper, we present an incremental synthesis procedure for a class of data path synthesis problems in which synthesis is carried out in a control step by control step fashion. The synthesis problems are classified according to the type of input dataflow graph (scheduled or unscheduled) and the type of storage units used (individual registers, single-port memory units, or multi-port memory units). These problems are solved optimally by employing either a network flow or 0–1 integer linear programming formulation. Experimental results on a number of benchmark problems are provided to demonstrate the effectiveness of the incremental synthesis algorithm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00924989
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  • 9
    Digitale Medien
    Digitale Medien
    Simulation of microstructure evolution during pulsed-laser annealing and ablation of solid mnterinlc (1996)
    Springer
    Journal of computer-aided materials design 3 (1996), S. 238-244 
    Details
    ISSN: 1573-4900
    Schlagwort(e): Modeling ; Simulation ; Laser annealing and ablation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Summary Microstructure evolution in an amorphous layer of Si (a-Si) irradiated by pulsed lasers has been investigated using a two-dimensional heat-conduction, phase-change, and microstructure simulation model. The approach has several unique features for describing nonequilibrium phase transformations under the extreme conditions of pulsed-laser annealing and ablation, e.g., the concepts of the state diagram and the state array. The approach has been used to study several problems related to the annealing and ablation of solids by pulsed lasers, e.g., (i) dynamics of ‘explosively’ propagating buried liquid layers during pulsed-laser annealing of an a-Si layer on a c-Si substrate; (ii) dynamics of Si ‘flake’ nucleation and growth and the resulting final microstructures for various laser energy densities;, (iii) ablation due to absorption by localized but extended defects such as occurs in the case of MgO; (iv) particulate ejection during laser ablation and matrix-assisted laser desorption ionization (MALDI). The results from the modeling and simulation are compared to experimental measurements and observations. Quantitative and qualitative agreement between experiment and theory demonstrate that the approach can be applied to a variety of problems and for many different materials.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01185659
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  • 10
    Digitale Medien
    Digitale Medien
    Novel bioseparations using two-phase aqueous micellar systems (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 52 (1996), S. 185-192 
    Details
    ISSN: 0006-3592
    Schlagwort(e): aqueous micellar system ; hydrophilic protein ; excluded-volume interactions ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: We review our recent experimental and theoretical work aimed at investigating the potential use of two-phase aqueous micellar systems for the separation or concentration of hydrophilic biomaterials using the principle of liquid-liquid extraction. The systems studied include (1) a two-phase aqueous micellar system composed of the nonionic surfactant n-decyl tetra(ethylene oxide) (C10E4) and (2) a two-phase aqueous micellar system composed of the zwitterionic surfactant dioctanoyl phosphatidyl-choline (C8-lecithin). The experimental partitioning behavior of several hydrophilic proteins, including cytochrome c, soybean trypsin inhibitor, ovalbumin, bovine serum albumin, and catalase, in two-phase aqueous C10E4 and C8-lecithin micellar systems is reviewed. A theoretical formulation of the protein partitioning behavior, based on a description of excluded-volume interactions between the hydrophilic proteins and the micelles, is also reviewed. The theoretically predicted protein partitioning behavior is compared with that observed experimentally and is found to be in good agreement. The results of our investigation suggest that two-phase aqueous micellar systems of the type examined in this article are indeed potentially useful as extractant phases for the separation or concentration of proteins and other biomaterials. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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