High surface porosity as the origin of emissivity features in asteroid spectra

This study numerically investigated the behavior of a Newtonian droplet impacting a heated porous surface. In this regard, a two-phase finite volume code was used for laminar flow. The time adaptive method was applied to enhance the accuracy of results and better convergence of the solving process. Also, the dynamic grid adaptation technique was adopted to predict the liquid-air interface precisely. The results were first validated against experimental data at different Weber numbers. Then the effect of variations in the droplet temperature was investigated on the spreading factor. The obtained results revealed that the rise in droplet temperature led to an increase in the maximum spreading diameter due to the reduction in the effects of viscosity, density, and surface tension. In the next step, the effects of droplet impact on the hydrophilic and superhydrophobic surfaces with the porosities of 20–80% were evaluated. The obtained results revealed that the increase in the surface porosity caused a decrease in the droplet diameter during the impact time. Also, at high surface porosity values, the decline in the contact angle influence on the droplet dynamic behavior was observed.

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Simulation on Pore Formation from Polymer Solution at Surface in Contact with Solid Substrate via Thermally Induced Phase Separation

Membranes ◽

10.3390/membranes11070527 ◽

2021 ◽

Vol 11 (7) ◽

pp. 527

Author(s):

Yasushi Mino ◽

Naruki Fukukawa ◽

Hideto Matsuyama

Keyword(s):

Phase Separation ◽

Polymer Solution ◽

Solid Surface ◽

Pore Formation ◽

High Surface ◽

Phase Field Method ◽

Coagulation Bath ◽

Surface Porosity ◽

Thermally Induced Phase Separation ◽

Thermally Induced

The formation of porous structures from polymer solutions at the surface in contact with various solid surfaces via a thermally-induced phase separation (TIPS) process is investigated. The pore formation process at the bulk and the surface of the poly(methyl methacrylate)/cyclohexanol solution is simulated with a model based on the phase field method. When the compatibilities between the polymer-rich phase formed by the phase separation and the solid surface are high or low, surface porosity decreases. In contrast, for the solid surface having similar compatibilities with the polymer and solvent, high surface porosity is achieved. This indicates that the compatibility between the solid surface and polymer solution is important, and that optimal compatibility results in high surface porosity. The knowledge obtained in this work is useful to design the coagulation bath component in the membrane preparation process by TIPS for achieving high surface porosity.

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Characterization of Wet Impregnation Method for Catalytic Microcombustor by Using Platinum

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.699.163 ◽

2014 ◽

Vol 699 ◽

pp. 163-168

Author(s):

Nazri Murat Muhamad ◽

Azman Miskam Muhamad ◽

Ahmad Mohd Azmier ◽

Zainal Alimuddin Zainal Alauddin ◽

Zulfikar Ishak Mohammad

Keyword(s):

High Surface ◽

Catalyst Support ◽

Propargyl Alcohol ◽

Support Surface ◽

Impregnation Method ◽

Surface Porosity ◽

Wet Impregnation ◽

Surface Areas ◽

Wet Impregnation Method

The wet impregnation method for catalytic microcombustor was characterized by using platinum as a catalyst. The main purpose of this study is to increase the surface porosity of the catalyst support. A high surface porosity indicates that a high amount of catalyst was deposited within the surface areas. The performance of the catalytic microcombustor improves with increasing catalytic surface area. The stainless steel catalyst support was treated with sulfuric acid solution containing polyvinyl (3.89 wt%) and propargyl alcohol (1.48 wt%). Combustion test was performed using LPG-air to test the performance of the catalyst. The surface support treated with polyvinyl (PVA) showed a higher surface porosity and combustion blow-out limit compared with propargyl alcohol. The combustion mode changes from surface to submerged combustion after the catalyst was deposited in the support surface.

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Electron Microscopic Investigation on Nanostructure Behaviors of Thermal Oxidation Copper

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.694.116 ◽

2016 ◽

Vol 694 ◽

pp. 116-119

Author(s):

Siti Rahmah Esa ◽

Ghazali Omar ◽

Rosiyah Yahya ◽

Noreffendy Tamaldin ◽

Aziz Hassan ◽

...

Keyword(s):

Copper Oxide ◽

High Surface ◽

Oxide Particle ◽

Electron Microscopic Investigation ◽

Oxidation Temperature ◽

Particle Nucleation ◽

Surface Porosity ◽

Electron Microscopic ◽

Porosity Level ◽

High Oxidation

A copper alloy consists of 2.6% Fe, 0.15% P and 0.2% Zn with modified grain size of 500 and 750 nm were studied on their rate of diffusion at different oxidation temperature using electron microscopic imaging technique. Different oxidation temperature contributed to the variation of copper oxide particle size, surface porosity level, particle agglomeration and particle nucleation. High oxidation temperature resulted in large oxide particles formation as well as high surface porosity. The magnitude of the copper oxide growth depended on the oxidation temperature. The increase in the oxidation rate at high oxidation temperature was likely a result of faster transport of the reactants through the bulk copper due to a significant contribution from grain-boundary diffusion.

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The Effect of Current Supply Duration during Stepwise Electrical Sintering of Silver Nanoparticles

Metals ◽

10.3390/met11111878 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1878

Author(s):

Iksang Lee ◽

Arif Hussain ◽

Hee-Lak Lee ◽

Yoon-Jae Moon ◽

Jun-Young Hwang ◽

...

Keyword(s):

Printed Electronics ◽

Specific Resistance ◽

High Surface ◽

Sem Analysis ◽

Surface Porosity ◽

Ag Nps ◽

Time Duration ◽

Time Intervals ◽

Temperature Estimation ◽

Glass Substrates

We studied the effect of current supply duration at final-step currents during the stepwise electrical sintering of silver (Ag) nanoparticles (NPs). Ag NPs ink was inkjet-printed onto Eagle-XG glass substrates. Constant final-step currents of 0.4 and 0.5 A with various time intervals were applied to the printed samples. The final-step current of 0.5 A damaged the line at a comparatively shorter time duration. On the other hand, the lower final-step current of 0.4 A prevented the line damage at longer time durations while producing comparatively lower Ag NPs specific resistance. The minimum specific resistances of the printed samples sintered at 0.4 and 0.5 A were 3.59 μΩ∙cm and 3.79 μΩ∙cm, respectively. Furthermore, numerical temperature estimation and scanning electron microscope (SEM) analysis were conducted to elaborate on the results. The numerical temperature estimation results implied that the lower estimated peak temperature at the final-step current of 0.4 A helped prevent Ag NP line damage. The SEM micrographs suggested that a high surface porosity—caused by higher sintering peak temperatures—in the case of the 0.5 A final-step current resulted in a comparatively higher Ag NP line-specific resistance. This contribution is a step forward in the development of Ag NP sintering for printed electronics applications.

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Local Effects in EHL Contacts with Oil-Impregnated Sintered Materials

Lubricants ◽

10.3390/lubricants7010001 ◽

2018 ◽

Vol 7 (1) ◽

pp. 1 ◽

Cited By ~ 3

Author(s):

Martin Ebner ◽

Milan Omasta ◽

Thomas Lohner ◽

Petr Šperka ◽

Ivan Krupka ◽

...

Keyword(s):

Thin Film ◽

Surface Finish ◽

High Surface ◽

Surface Porosity ◽

Test Rig ◽

Local Effects ◽

Surface Finishes ◽

Sintered Materials ◽

Disk Test ◽

Highly Loaded

Oil-impregnated open-pored sintered materials can be used to provide the intrinsic self-lubrication of tribological contacts. Although its general functionality was recently confirmed for highly-loaded contacts, detailed analyses on the local effects of surface porosity in tribological contacts are required in order to understand and improve its operating behavior. In this context, this study investigates the influence of different surface finishes at a twin-disk test rig, and the local effects of surface porosity in elastohydrodynamically lubricated (EHL) contacts at an optical tribometer, based on thin film colorimetric interferometry. The results show the detrimental influence of high surface porosity on the operating behavior. Local observations of the lubricant film in EHL contacts indicate the presence of “open” pores, resulting in local film breakdown, and “closed” pores, transporting the additional lubricant into the pressurized zone. An appropriate surface finish technique to manufacture a low permeable layer with an adequate mechanical strength is demanded.

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Chemical Activation of Durian Shell Activated Carbon: Effects of Activation Agents

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1113.242 ◽

2015 ◽

Vol 1113 ◽

pp. 242-247

Author(s):

Wan Norasiah Wan Mahmood ◽

Rusnah Samsuddin ◽

Raja Razuan Raja Deris

Keyword(s):

Activated Carbon ◽

Surface Area ◽

Potassium Hydroxide ◽

Chemical Activation ◽

High Surface ◽

High Surface Area ◽

Total Pore Volume ◽

Surface Porosity ◽

Micropore Surface Area ◽

Selection Of

Selection of suitable activation agent is important in order to produce high surface area of activated carbon. The present study was undertaken to develop high surface area of durian shell activated carbon (DSAC) using different chemical activation agents which were potassium hydroxide (KOH) and phosphoric acid (H3PO4). Surface porosity and surface area were directly measured from scanning electron microscopy (SEM) and surface area analyzer, respectively. For the optimum condition, it showed that H3PO4 treated DSAC had the highest surface area which was 257.50 m2/g compared to KOH treated DSAC which was 13.10 m2/g. H3PO4 treated DSAC also showed the highest micropore surface area, external surface area and total pore volume with 191.22 m2/g, 66.28 m2/g and 0.149 cm3/g, respectively. SEM result showed that H3PO4 treated DSAC had a well pronounce porosity than durian shell char. Surface area and surface porosity were important in an adsorption process.

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Localization of Adenosine Triphosphatase Activity in the Phleom of Nicotiana Tabacum

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100094401 ◽

1972 ◽

Vol 30 ◽

pp. 230-231

Author(s):

James Cronshaw ◽

Jamison E. Gilder

Keyword(s):

Plasma Membrane ◽

Atpase Activity ◽

Adenosine Triphosphatase ◽

Higher Plants ◽

High Surface ◽

Root Tip ◽

Animal Cells ◽

Physiological Processes ◽

Tip Cells ◽

Atpase Localization

Adenosine triphosphatase (ATPase) activity has been shown to be associated with numerous physiological processes in both plants and animal cells. Biochemical studies have shown that in higher plants ATPase activity is high in cell wall preparations and is associated with the plasma membrane, nuclei, mitochondria, chloroplasts and lysosomes. However, there have been only a few ATPase localization studies of higher plants at the electron microscope level. Poux (1967) demonstrated ATPase activity associated with most cellular organelles in the protoderm cells of Cucumis roots. Hall (1971) has demonstrated ATPase activity in root tip cells of Zea mays. There was high surface activity largely associated with the plasma membrane and plasmodesmata. ATPase activity was also demonstrated in mitochondria, dictyosomes, endoplasmic reticulum and plastids.

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Anisotropic Membranes as Substrates for Sem

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092189 ◽

1976 ◽

Vol 34 ◽

pp. 444-445

Author(s):

Thomas P. Turnbull ◽

W. F. Bowers

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Transmission Electron Microscopy ◽

High Flow ◽

Polymer Chemistry ◽

Surface Porosity ◽

Transmission Electron ◽

Pore Texture ◽

Spongy Layer ◽

Scanning Electron

Until recently the prime purposes of filters have been to produce clear filtrates or to collect particles from solution and then remove the filter medium and examine the particles by transmission electron microscopy. These filters have not had the best characteristics for scanning electron microscopy due to the size of the pores or the surface topography. Advances in polymer chemistry and membrane technology resulted in membranes whose characteristics make them versatile substrates for many scanning electron microscope applications. These polysulphone type membranes are anisotropic, consisting of a very thin (0.1 to 1.5 μm) dense skin of extremely fine, controlled pore texture upon a much thicker (50 to 250μm), spongy layer of the same polymer. Apparent pore diameters can be controlled in the range of 10 to 40 A. The high flow ultrafilters which we are describing have a surface porosity in the range of 15 to 25 angstrom units (0.0015-0.0025μm).

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In Situ microscopy of the anodic etching of silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137537 ◽

1995 ◽

Vol 53 ◽

pp. 232-233

Author(s):

Frances M. Ross ◽

Peter C. Searson

Keyword(s):

Composite Structures ◽

High Surface ◽

High Surface Area ◽

Chemical Properties ◽

Selective Etching ◽

Silicon On Insulator ◽

Second Phase ◽

Porous Layers ◽

New Class ◽

Porous Semiconductors

Porous semiconductors represent a relatively new class of materials formed by the selective etching of a single or polycrystalline substrate. Although porous silicon has received considerable attention due to its novel optical properties1, porous layers can be formed in other semiconductors such as GaAs and GaP. These materials are characterised by very high surface area and by electrical, optical and chemical properties that may differ considerably from bulk. The properties depend on the pore morphology, which can be controlled by adjusting the processing conditions and the dopant concentration. A number of novel structures can be fabricated using selective etching. For example, self-supporting membranes can be made by growing pores through a wafer, films with modulated pore structure can be fabricated by varying the applied potential during growth, composite structures can be prepared by depositing a second phase into the pores and silicon-on-insulator structures can be formed by oxidising a buried porous layer. In all these applications the ability to grow nanostructures controllably is critical.

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