scholarly journals B116 Enhanced Boiling of FC-72 on Silicon Chips with Submicron-Scale Roughness

2001 ◽  
Vol 2001 (0) ◽  
pp. 87-88
Author(s):  
Jinjia WEI ◽  
Hiroshi HONDA ◽  
Hiroshi TAKAMATSU
2001 ◽  
Vol 124 (2) ◽  
pp. 383-390 ◽  
Author(s):  
H. Honda ◽  
H. Takamastu ◽  
J. J. Wei

Experiments were conducted to study the effects of micro-pin-fins and submicron-scale roughness on the boiling heat transfer from a silicon chip immersed in a pool of degassed and gas-dissolved FC-72. Square pin-fins with fin dimensions of 50×50×60μm3 (width×thickness×height) and submicron-scale roughness (RMS roughness of 25 to 32 nm) were fabricated on the surface of square silicon chip 10×10×0.5mm3 by use of microelectronic fabrication techniques. Experiments were conducted at the liquid subcoolings of 0, 3, 25, and 45 K. Both the micro-pin-finned chip and the chip with submicron-scale roughness showed a considerable heat transfer enhancement as compared to a smooth chip in the nucleate boiling region. The chip with submicron-scale roughness showed a higher heat transfer performance than the micro-pin-finned chip in the low-heat-flux region. The micro-pin-finned chip showed a steep increase in the heat flux with increasing wall superheat. This chip showed a higher heat transfer performance than the chip with submicron-scale roughness in the high-heat-flux region. The micro-pin-finned chip with submicron-scale roughness on it showed the highest heat transfer performance in the high-heat-flux region. While the wall superheat at boiling incipience was strongly dependent on the dissolved gas content, it was little affected by the liquid subcooling.


Author(s):  
P. Fraundorf ◽  
B. Armbruster

Optical interferometry, confocal light microscopy, stereopair scanning electron microscopy, scanning tunneling microscopy, and scanning force microscopy, can produce topographic images of surfaces on size scales reaching from centimeters to Angstroms. Second moment (height variance) statistics of surface topography can be very helpful in quantifying “visually suggested” differences from one surface to the next. The two most common methods for displaying this information are the Fourier power spectrum and its direct space transform, the autocorrelation function or interferogram. Unfortunately, for a surface exhibiting lateral structure over several orders of magnitude in size, both the power spectrum and the autocorrelation function will find most of the information they contain pressed into the plot’s origin. This suggests that we plot power in units of LOG(frequency)≡-LOG(period), but rather than add this logarithmic constraint as another element of abstraction to the analysis of power spectra, we further recommend a shift in paradigm.


2003 ◽  
Vol 775 ◽  
Author(s):  
Ivan Stanish ◽  
Daniel A. Lowy ◽  
Alok Singh

AbstractImmobilized polymerized electroactive vesicles (IPEVs) are submicron biocapsules capable of storing charge in confined environments and chemisorbing on surfaces. Methods to immobilize stable submicron sized electroactive vesicles and the means to measure electroactivity of IPEVs at nanolevels have been demonstrated. IPEVs can withstand steep potential gradients applied across their membrane, maintain their structural integrity against surfaces poised at high/low electrical potentials, retain electroactive material over several days, and reversibly mediate (within the membrane) electron flow between the electrode surface and vesicle interior. IPEVs have strong potential to be used for charge storage and electron coupling applications that operate on the submicron scale and smaller.


Author(s):  
David Segal

Chapter 3 highlights the critical role materials have in the development of digital computers. It traces developments from the cat’s whisker to valves through to relays and transistors. Accounts are given for transistors and the manufacture of integrated circuits (silicon chips) by use of photolithography. Future potential computing techniques, namely quantum computing and the DNA computer, are covered. The history of computability and Moore’s Law are discussed.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Katharina R. Lenhardt ◽  
Hergen Breitzke ◽  
Gerd Buntkowsky ◽  
Erik Reimhult ◽  
Max Willinger ◽  
...  

AbstractWe report here on structure-related aggregation effects of short-range ordered aluminosilicates (SROAS) that have to be considered in the development of synthesis protocols and may be relevant for the properties of SROAS in the environment. We synthesized SROAS of variable composition by neutralizing aqueous aluminium chloride with sodium orthosilicate at ambient temperature and pressure. We determined elemental composition, visualized morphology by microscopic techniques, and resolved mineral structure by solid-state 29Si and 27Al nuclear magnetic resonance and Fourier-transform infrared spectroscopy. Nitrogen sorption revealed substantial surface loss of Al-rich SROAS that resembled proto-imogolite formed in soils and sediments due to aggregation upon freezing. The effect was less pronounced in Si-rich SROAS, indicating a structure-dependent effect on spatial arrangement of mass at the submicron scale. Cryomilling efficiently fractured aggregates but did not change the magnitude of specific surface area. Since accessibility of surface functional groups is a prerequisite for sequestration of substances, elucidating physical and chemical processes of aggregation as a function of composition and crystallinity may improve our understanding of the reactivity of SROAS in the environment.


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