scholarly journals Liquid-State Dewetting of Pulsed-Laser-Heated Nanoscale Metal Films and Other Geometries

2020 ◽  
Vol 52 (1) ◽  
pp. 235-262 ◽  
Author(s):  
Lou Kondic ◽  
Alejandro G. González ◽  
Javier A. Diez ◽  
Jason D. Fowlkes ◽  
Philip Rack
Keyword(s):  
Materials Science ◽  
Research Area ◽  
Metal Films ◽  
Contact Angles ◽  
Thin Metal Film ◽  
Thermal Physics ◽  
Science Community ◽  
Physical Effects ◽  
Laser Heated ◽  
Bimetallic Films

Metal films of nanoscale thickness, deposited on substrates and exposed to laser heating, provide systems that involve several interesting multiphysics effects. In addition to fluid mechanical aspects associated with a free boundary setup, other relevant physical effects include phase change, thermal flow, and liquid–solid interactions. Such films are challenging to model, in particular because inertial effects may be relevant, and large contact angles require care when considering the long-wave formulation. Applications of nanoscale metal films are numerous, and the materials science community is actively pursuing more complex setups involving templated films and substrates, bimetallic films and alloys, and a variety of elemental film geometries. The goal of this review is to discuss our current understanding of thin metal film systems, while also providing an overview of the challenges in this research area, which stands at the intersection of fluid mechanics, materials science, and thermal physics.

Electron holography of interfaces in electroceramics

1993 ◽  
Vol 51 ◽  
pp. 1088-1089
Author(s):  
Vinayak P. Dravid ◽  
V. Ravikumar ◽  
Richard Plass
Keyword(s):  
Space Charge ◽  
Direct Evidence ◽  
Materials Science ◽  
Theoretical Work ◽  
Electron Holography ◽  
Resolution Limit ◽  
Interference Phenomenon ◽  
X Ray ◽  
Electron Sources ◽  
Science Community

With the advent of coherent electron sources with cold field emission guns (cFEGs), it has become possible to utilize the coherent interference phenomenon and perform “practical” electron holography. Historically, holography was envisioned to extent the resolution limit by compensating coherent aberrations. Indeed such work has been done with reasonable success in a few laboratories around the world. However, it is the ability of electron holography to map electrical and magnetic fields which has caught considerable attention of materials science community.There has been considerable theoretical work on formation of space charge on surfaces and internal interfaces. In particular, formation and nature of space charge have important implications for the performance of numerous electroceramics which derive their useful properties from electrically active grain boundaries. Bonnell and coworkers, in their elegant STM experiments provided the direct evidence for GB space charge and its sign, while Chiang et al. used the indirect but powerful technique of x-ray microchemical profiling across GBs to infer the nature of space charge.

Doppler-Shifted Cyclotron Resonance in Thin Metal Films

1972 ◽  
Vol 50 (18) ◽  
pp. 2122-2137
Author(s):  
R. Turner ◽  
J. F. Cochran
Keyword(s):  
Magnetic Field ◽  
Metal Films ◽  
Thin Metal Film ◽  
Thin Metal ◽  
Free Electrons ◽  
Fermi Surfaces ◽  
First Order ◽  
Simple Quantum ◽  
The Magnetic Field ◽  
Good Agreement

According to Van Gelder the microwave absorption by a thin metal film in the presence of a static magnetic field normal to the film contains a series of peaks as the magnetic field is varied. In the present paper it is argued that these peaks correspond to Doppler-shifted cyclotron resonances of the carriers in the metal due to the quantization of electron momenta normal to the plane of the film. A simple quantum calculation is presented for the case of free electrons where the film is thin enough that to first order the microwave fields within are determined only by the boundary conditions and Maxwell's equations. The quantum expression is in good agreement with the absorption calculated using semiclassical arguments which can be readily extended to more complicated Fermi surfaces.

scholarly journals Ab Initio Study of the Electronic, Vibrational, and Mechanical Properties of the Magnesium Diboride Monolayer

2019 ◽  
Vol 4 (2) ◽  
pp. 37 ◽  
Author(s):  
Jelena Pešić ◽  
Igor Popov ◽  
Andrijana Šolajić ◽  
Vladimir Damljanović ◽  
Kurt Hingerl ◽  
...  
Keyword(s):  
Ab Initio ◽  
First Principles ◽  
Materials Science ◽  
Magnesium Diboride ◽  
Poisson Ratio ◽  
Single Layer ◽  
First Principles Calculations ◽  
Significant Interest ◽  
Science Community ◽  
Fundamental Research

Magnesium diboride gained significant interest in the materials science community after the discovery of its superconductivity, with an unusually high critical temperature of 39 K. Many aspects of the electronic properties and superconductivity of bulk MgB 2 and thin sheets of MgB 2 have been determined; however, a single layer of MgB 2 has not yet been fully theoretically investigated. Here, we present a detailed study of the structural, electronic, vibrational, and elastic properties of monolayer MgB 2 , based on ab initio methods. First-principles calculations reveal the importance of reduction of dimensionality on the properties of MgB 2 and thoroughly describe the properties of this novel 2D material. The presence of a negative Poisson ratio, higher density of states at the Fermi level, and a good dynamic stability under strain make the MgB 2 monolayer a prominent material, both for fundamental research and application studies.

A brief overview of Materials Science in Uruguay

MRS Advances ◽  
2018 ◽  
Vol 3 (61) ◽  
pp. 3535-3541
Author(s):  
Ivana Aguiar ◽  
Livia Arizaga ◽  
Santiago Botasini ◽  
María Andrea De León ◽  
Sofia Favre ◽  
...  
Keyword(s):  
Materials Science ◽  
Research Area ◽  
Steady State Regime ◽  
Area Of Interest ◽  
Starting Point ◽  
State Regime ◽  
Scopus Database ◽  
Number Of Publications ◽  
Funding Opportunities

ABSTRACTMaterials science is a growing research area in Uruguay. In order to obtain a brief overview of the research done we collected information about research in this field. As a starting point, we searched in the Scopus database for the keywords: affiliation country: “Uruguay” and subject: “Materials Science” (using the “Timbó” platform). We inspected the records and we analyzed them to construct a timeline. The data show that we are in a steady state regime of number of publications that we expect to increase together with the number of students in the area, with the generation of long term policies (grants, funding opportunities), and, if we get involved in a community that promotes this area of interest.

Development of Thin Metal Film Corrosion Indicators

CORROSION ◽  
1960 ◽  
Vol 16 (8) ◽  
pp. 399t-404t ◽  
Author(s):  
DAVID ROLLER ◽  
G. H. ROHRBACK
Keyword(s):  
Development Program ◽  
Feasibility Studies ◽  
Metal Films ◽  
Thin Metal Film ◽  
Thin Metal ◽  
Metallic Substrates ◽  
Final Development ◽  
Percent Relative Humidity ◽  
And Behavior ◽  
And Storage

Abstract An account is given of the development of visual and electrical corrosion indicators which utilize thin metal films vacuum-deposited on non-metallic substrates. Data are presented showing the behavior of these indicators in corrosive atmospheres. Although the indicators were developed primarily to detect and mark corrosive conditions in packages and storage areas, other possible applications are described briefly. Data reported include comparative corrosion information on electrical cards and buttons in various humid atmospheres, condition of visual and resistance thin film indicators at first sign of corrosion on hardware items, and behavior of polyvinyl resistance card indicators at different sensitizations at 25 C and 60 percent relative humidity. The paper presents the progress of this development program from the feasibility studies through the final development of manufacturing protypes. 3.23

scholarly journals Visual Computing and Machine Learning Techniques for Digital Forensics

2015 ◽  
Vol 22 (1) ◽  
pp. 128 ◽  
Author(s):  
Tiago Jose de Carvalho ◽  
Helio Pedrini ◽  
Anderson De Rezende Rocha
Keyword(s):  
Machine Learning ◽  
Digital Image ◽  
Digital Forensics ◽  
Research Area ◽  
Digital Image Forensics ◽  
Machine Learning Techniques ◽  
Open Problems ◽  
Visual Computing ◽  
Science Community ◽  
New Research

It is impressive how fast science has improved day by day in so many different fields. In special, technology advances are shocking so many people bringing to their reality facts that previously were beyond their imagination. Inspired by methods earlier presented in scientific fiction shows, the computer science community has created a new research area named Digital Forensics, which aims at developing and deploying methods for fighting against digital crimes such as digital image forgery.This work presents some of the main concepts associated with Digital Forensics and, complementarily, presents some recent and powerful techniques relying on Computer Graphics, Image Processing, Computer Vision and Machine Learning concepts for detecting forgeries in photographs. Some topics addressed in this work include: sourceattribution, spoofing detection, pornography detection, multimedia phylogeny, and forgery detection. Finally, this work highlights the challenges and open problems in Digital Image Forensics to provide the readers with the myriad opportunities available for research.

scholarly journals Bacterial Nanocellulose Nitrates

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1694 ◽  
Author(s):  
Vera V. Budaeva ◽  
Yulia A. Gismatulina ◽  
Galina F. Mironova ◽  
Ekaterina A. Skiba ◽  
Evgenia K. Gladysheva ◽  
...  
Keyword(s):  
Materials Science ◽  
Analytical Techniques ◽  
High Viscosity ◽  
Research Area ◽  
Cellulose Content ◽  
Bacterial Nanocellulose ◽  
Mixed Acid ◽  
13C Nuclear Magnetic Resonance ◽  
Freeze Dried ◽  
Application Fields

Bacterial nanocellulose (BNC) whose biosynthesis fully conforms to green chemistry principles arouses much interest of specialists in technical chemistry and materials science because of its specific properties, such as nanostructure, purity, thermal stability, reactivity, high crystallinity, etc. The functionalization of the BNC surface remains a priority research area of polymers. The present study was aimed at scaled production of an enlarged BNC sample and at synthesizing cellulose nitrate (CN) therefrom. Cyclic biosynthesis of BNC was run in a semisynthetic glucose medium of 10−72 L in volume by using the Medusomyces gisevii Sa-12 symbiont. The most representative BNC sample weighing 6800 g and having an α-cellulose content of 99% and a polymerization degree of 4000 was nitrated. The nitration of freeze-dried BNC was performed with sulfuric-nitric mixed acid. BNC was examined by scanning electron microscopy (SEM) and infrared spectroscopy (IR), and CN was explored to a fuller extent by SEM, IR, thermogravimetric analysis/differential scanning analysis (TGA/DTA) and 13C nuclear magnetic resonance (NMR) spectroscopy. The three-cycle biosynthesis of BNC with an increasing volume of the nutrient medium from 10 to 72 L was successfully scaled up in nonsterile conditions to afford 9432 g of BNC gel-films. CNs with a nitrogen content of 10.96% and a viscosity of 916 cP were synthesized. It was found by the SEM technique that the CN preserved the 3D reticulate structure of initial BNC fibers a marginal thickening of the nanofibers themselves. Different analytical techniques reliably proved the resultant nitration product to be CN. When dissolved in acetone, the CN was found to form a clear high-viscosity organogel whose further studies will broaden application fields of the modified BNC.

Determination of Contact Angles of Nanosized Silica Particles by Multi-Angle Single-Wavelength Ellipsometry

2007 ◽  
Vol 60 (9) ◽  
pp. 651 ◽  
Author(s):  
Timothy N. Hunter ◽  
Graeme J. Jameson ◽  
Erica J. Wanless
Keyword(s):  
Materials Science ◽  
Practical Importance ◽  
Contact Angles ◽  
Equilibrium Contact Angle ◽  
Science And Engineering ◽  
Air Water Interface ◽  
Specific Contact ◽  
Materials Science And Engineering ◽  
Two Layer Model

The determination of nanoparticle wettability is an area of great practical importance to materials science and engineering fields. There has been some recent interest in using spectroscopic analysis to indirectly categorize behaviour of monolayers, using the reflective and refractive properties of immersed particles. A method is developed here to calculate specific contact information for nanoparticles at an air–water interface, using single wavelength ellipsometry. A two-layer model is used that considers the refractive index of the immersed and non-immersed particle portions. Pressure–area isotherms and Brewster angle images were used to confirm and categorize the nature of a packed monolayer, and ψ and Δ measurements taken of the interface. Immersion thickness was calculated and related to an equilibrium contact angle, and combined thickness data for the two layers was successfully related to the diameter of the particles.

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