3,410 research outputs found
Data display and analysis
Graphical character recognizer and data displa
The texture of thin NiSi films and its effect on agglomeration
Nickel silicide films are used as contacting materials in the micro electronics industry. It was recently [1] discovered that these films exhibit a peculiar type of texture, which was called 'axiotaxy', whereby certain lattice planes in the NiSi grains are preferentially aligned to (110)-type lattice planes in the single crystal Si substrate. In this contribution, we present a quantitative study of this phenomenon, using both XRD pole figure measurements and EBSD. Furthermore, we report a correlation between the texture of these NiSi films and their morphological stability during annealing at high temperature.
In spite of the small grain size in these films, EBSD could be used to determine the volume fractions of the various texture components. This provided quantitative support for the claim that axiotaxy is the main texture component in these films, as about 40% of the grains belong to one of the axiotaxial texture components, and the remaining fraction exhibits a random orientation. A discussion of the techniques used during the measurement and analysis of the EBSD data is presented, as this must be given special consideration in view of the peculiar type of texture encountered in these films.
Secondly, both XRD and EBSD were performed after annealing the NiSi films at various temperatures and durations. It is known that thin NiSi films have a strong tendency to agglomerate [2]. Our data indicates a correlation between the texture evolution and the agglomeration of the NiSi layer. Grains with axiotaxial orientation were observed to grow and thicken during the annealing process, by consuming neighboring randomly oriented grains. This suggests that the texture of the NiSi layer is a determining factor for the morphological stability of the film. The fact that grains with axiotaxial orientation grow during heat treatment can be related to the one dimensional periodicity at the interface, which lowers the interface energy and thus provides a driving force for the preferred growth of these grains. The agglomeration of NiSi films results in a significant increase of the sheet resistance. Therefore, these results illustrate the importance of texture control for the application of these films as contacts in micro-electronic devices
Particle Acceleration in Turbulence and Weakly Stochastic Reconnection
Fast particles are accelerated in astrophysical environments by a variety of
processes. Acceleration in reconnection sites has attracted the attention of
researchers recently. In this letter we analyze the energy distribution
evolution of test particles injected in three dimensional (3D)
magnetohydrodynamic (MHD) simulations of different magnetic reconnection
configurations. When considering a single Sweet-Parker topology, the particles
accelerate predominantly through a first-order Fermi process, as predicted in
previous work (de Gouveia Dal Pino & Lazarian, 2005) and demonstrated
numerically in Kowal, de Gouveia Dal Pino & Lazarian (2011). When turbulence is
included within the current sheet, the acceleration rate, which depends on the
reconnection rate, is highly enhanced. This is because reconnection in the
presence of turbulence becomes fast and independent of resistivity (Lazarian &
Vishniac, 1999; Kowal et al., 2009) and allows the formation of a thick volume
filled with multiple simultaneously reconnecting magnetic fluxes. Charged
particles trapped within this volume suffer several head-on scatterings with
the contracting magnetic fluctuations, which significantly increase the
acceleration rate and results in a first-order Fermi process. For comparison,
we also tested acceleration in MHD turbulence, where particles suffer
collisions with approaching and receding magnetic irregularities, resulting in
a reduced acceleration rate. We argue that the dominant acceleration mechanism
approaches a second order Fermi process in this case.Comment: 6 pages, 1 figur
Residual tumor cells that drive disease relapse after chemotherapy do not have enhanced tumor initiating capacity.
Although chemotherapy is used to treat most advanced solid tumors, recurrent disease is still the major cause of cancer-related mortality. Cancer stem cells (CSCs) have been the focus of intense research in recent years because they provide a possible explanation for disease relapse. However, the precise role of CSCs in recurrent disease remains poorly understood and surprisingly little attention has been focused on studying the cells responsible for re-initiating tumor growth within the original host after chemotherapy treatment. We utilized both xenograft and genetically engineered mouse models of non-small cell lung cancer (NSCLC) to characterize the residual tumor cells that survive chemotherapy treatment and go on to cause tumor regrowth, which we refer to as tumor re-initiating cells (TRICs). We set out to determine whether TRICs display characteristics of CSCs, and whether assays used to define CSCs also provide an accurate readout of a cell's ability to cause tumor recurrence. We did not find consistent enrichment of CSC marker positive cells or enhanced tumor initiating potential in TRICs. However, TRICs from all models do appear to be in EMT, a state that has been linked to chemoresistance in numerous types of cancer. Thus, the standard CSC assays may not accurately reflect a cell's ability to drive disease recurrence
Onset of Fast Magnetic Reconnection in Partially Ionized Gases
We consider quasi-stationary two-dimensional magnetic reconnection in a
partially ionized incompressible plasma. We find that when the plasma is weakly
ionized and the collisions between the ions and the neutral particles are
significant, the transition to fast collisionless reconnection due to the Hall
effect in the generalized Ohm's law is expected to occur at much lower values
of the Lundquist number, as compared to a fully ionized plasma case. We
estimate that these conditions for fast reconnection are satisfied in molecular
clouds and in protostellar disks.Comment: 19 pages, 1 figure, 1 tabl
Phase formation and thermal stability of ultrathin nickel-silicides on Si(100)
The solid-state reaction and agglomeration of thin nickel-silicide films was investigated from sputter deposited nickel films (1-10 nm) on silicon-on-insulator (100) substrates. For typical anneals at a ramp rate of 3 degrees C/s, 5-10 nm Ni films react with silicon and form NiSi, which agglomerates at 550-650 degrees C, whereas films with a thickness of 3.7 nm of less were found to form an epitaxylike nickel-silicide layer. The resulting films show an increased thermal stability with a low electrical resistivity up to 800 degrees C
Rhetoric in the language of real estate marketing
“Des. Res.”, “rarely available”, “viewing essential” – these are all part of the peculiar parlance of housing advertisements which contain a heady mix of euphemism, hyperbole and superlative. Of interest is whether the selling agent’s penchant for rhetoric is spatially uniform or whether there are variations across the urban system. We are also interested in how the use of superlatives varies over the market cycle and over the selling season. For example, are estate agents more inclined to use hyperbole when the market is buoyant or when it is flat, and does it matter whether a house is marketed in the summer or winter? This paper attempts to answer these questions by applying textual analysis to a unique dataset of 49,926 records of real estate transactions in the Strathclyde conurbation over the period 1999 to 2006. The analysis opens up a new avenue of research into the use of real estate rhetoric and its interaction with agency behaviour and market dynamics
Numerical Analysis of 3-Dimensional Scaling Rules on a 1.2-kV Trench Clustered IGBT
3-dimensional scaling rules for the cathode cells and
threshold voltages of a 1.2-kV Trench Clustered IGBT (TCIGBT)
are investigated using calibrated models in Synopsys Sentaurus
TCAD tools. Scaling down results in an enhancement of current
gain of the inherent thyristor action which reduces the forward
voltage drop even more than that of a scaled Trench IGBT
(TIGBT). For identical switching losses, at a scaling factor k=3,
the forward voltage drop is reduced by 20% at 300K and 30% at
400K when compared to the conventional TCIGBT (k=1). Most
importantly, despite its lower conduction losses than an
equivalent TIGBT, a scaled TCIGBT structure can maintain its
short circuit capability, due to the additional scaling principle
applied to the n-well and p-well regions, maintaining the
self-clamping feature. Thus, TCIGBT is a more efficient
chip-for-chip, reliable replacement of a TIGBT for energy savings
in applications
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Halving Food Loss and Waste in the EU by 2030: the major steps needed to accelerate progress
Unsustainable production and consumption of food constitutes one of the biggest environmental threats to our planet. Eliminating food loss and waste to the largest extent possible – at all stages from producer to final consumer – stands out as an urgent and indispensable step towards more sustainable food systems. The EU’s recent adoption of the Circular Economy Package, including the revision of its Waste Framework Directive in 2018 and a new Delegated Act on the measurement of food waste in 2019, opens a limited time period where Member States will have to integrate these policies into their national law. In 2020, the first EU-wide national measurement of food waste will be undertaken. This will be reported back to the EU mid2022 and will provide comparative baseline measures for all Member States. The publication of this baseline data in 2023 will provide the opportunity to consider the feasibility of establishing Union-wide food waste reduction targets to be met by 2025 and 2030. For this reason, 2020–2023 will provide crucial moments of opportunity for EU Member States’ food waste policy and EU-wide food waste reduction. Indeed, changes in the regulatory framework were necessary but need to be accompanied by further action to effectively accelerate food waste reductions. Through a rapid review of food waste literature and interviews with Member State representatives, this report identifies and provides case studies of the food waste reduction actions that have the largest evidence bases and largest potential for accelerating progress towards SDG target 12.3 (halving food waste by 2030 and reducing food losses), but which have been insufficiently applied in the EU until now: Food waste measurement; Valorisation; and Voluntary Agreements. Some of these actions are already partly developed in the EU (valorisation), while others have only recently been piloted across several Member States (voluntary agreements) or still need to be deployed coherently (food waste measurement). This report also highlights other interventions that show less evidence of their potential to date, but which are expected to hold high potential for effective food waste reduction: Changes to the Common Agricultural Policy; Stronger Regulation; and National Food Waste Strategies. Due to the interconnected nature of food waste, and of the EU and Member State policies, all food waste reduction areas proposed are interlinked and related. Together they offer a suite of actions that can be deployed over a range of time scales, from 12 months through to 5 years; and at a range of sizes, from individual companies or specific industry sectors, through to government-led deployment on a national scale. These actions will all benefit from close collaboration between the stakeholders, who can jointly deliver the urgently needed acceleration in food waste reduction
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