State of the Art of High Heat Flux Cooling Technologies

The purpose of this literature review is to compare different cooling technologies currently in development in research laboratories that are competing to solve the challenge of cooling the next generation of high heat flux computer chips. Today, most development efforts are focused on three technologies: liquid cooling in copper or silicon micro-geometry heat dissipation elements, impingement of liquid jets directly on the silicon surface of the chip, and two-phase flow boiling in copper heat dissipation elements or plates with numerous microchannels. The principal challenge is to dissipate the high heat fluxes (current objective is 300 W/cm²) while maintaining the chip temperature below the targeted temperature of 85°C, while of second importance is how to predict the heat transfer coefficients and pressure drops of the cooling process. In this study, the state of the art of these three technologies from recent experimental articles (since 2003) is analyzed and a comparison of the respective merits and drawbacks of each technology is presented. The conclusion is that two-phase flow boiling in microchannels is the most promising approach; impingement cooling also has good prospects but single-phase liquid cooling is probably only a short-term solution. As an example of the state of the first technology, the Heat and Mass Transfer Laboratory at Ecole Polytechnique Fédérale de Lausanne has already achieved 200 W/cm² of cooling in a first prototype, with a low pumping power, good temperature uniformity, and at the required maximal operating temperature.     

Trichlorosilanes as Anchoring Groups for Phenylene‐Thiophene Molecular Monolayer Field Effect Transistors

Self assembled monolayer field effect transistors (SAMFETs) are reported using a phenylene‐thiophene containing semiconducting mesogen attached through a trichlorosilane anchoring group. Monolayer films, covalently attached to silicon dioxide substrates, form in less than 10 h from solution, thanks to the accelerated reaction of the trichlorosilane anchor. Devices exhibit mobilities as high as 1.7 × 10^?2 cm² V^?1 s^?1, currents of up to 15 μA (on/off current ratio of 10⁶) with device yields close to unity over large areas for channel lengths up to 100 μm.     

Microscopic analysis of recycled paper effect on print quality parameters

To determine whether the geometrical accuracy of small printed elements does not worsen on recycled paper, microscopic analysis of the dot area and the graphic elements raggedness printed on different types of recycled and coated papers at different screen ruling was carried out. Experimental tests have shown that geometrical accuracy of small elements printed on recycled paper/cardboard, in comparison to pictures printed on primary production paper is almost the same. Microsc. Res. Tech. 76:890–892, 2013. © 2013 Wiley Periodicals, Inc.     

Optimal design of a Kirchhoff-Love plate of variable thickness by application of the minimum principle

Structural and Multidisciplinary Optimization - An approximate thickness optimization of a rectangular Kirchhoff-Love plate with variable stiffness under uniform load is performed in this paper....     

The Mechanism of Drug Nephrotoxicity and the Methods for Preventing Kidney Damage

Acute kidney injury (AKI) is a global health challenge of vast proportions, as approx. 13.3% of people worldwide are affected annually. The pathophysiology of AKI is very complex, but its main causes are sepsis, ischemia, and nephrotoxicity. Nephrotoxicity is mainly associated with the use of drugs. Drug-induced AKI accounts for 19–26% of all hospitalized cases. Drug-induced nephrotoxicity develops according to one of the three mechanisms: (1) proximal tubular injury and acute tubular necrosis (ATN) (a dose-dependent mechanism), where the cause is related to apical contact with drugs or their metabolites, the transport of drugs and their metabolites from the apical surface, and the secretion of drugs from the basolateral surface into the tubular lumen; (2) tubular obstruction by crystals or casts containing drugs and their metabolites (a dose-dependent mechanism); (3) interstitial nephritis induced by drugs and their metabolites (a dose-independent mechanism). In this article, the mechanisms of the individual types of injury will be described. Specific groups of drugs will be linked to specific injuries. Additionally, the risk factors for the development of AKI and the methods for preventing and/or treating the condition will be discussed.     

Effect of Specimen Thickness on the Oxidation Rate of High Chromium Ferritic Steels: The Significance of Intrinsic Alloy Creep Strength

Previous studies revealed that initial sample thickness affects the growth rate of oxide scales formed during 800 or 900 °C air exposure. The effect is partially related to differences in depletion of minor alloying additions such as Mn, Ti, La in thick and thin specimens. However, it has previously been proposed that the specimen thickness dependence is partially governed by differences in creep strength of thick and thin substrates. To investigate this hypothesis, discontinuous air oxidation experiments were carried out with the Laves phase strengthened ferritic steel Crofer 22 H at 800 °C. Comparing the data for solution annealed and pre-aged (500 h, 900 °C) materials it could be shown that intrinsic creep strength of the alloy substantially affects oxidation rates. The observations can qualitatively be explained by assuming the relaxation of oxide growth stresses by plastic deformation of the metallic substrate to be an important parameter affecting the kinetics of oxide scale growth.     

Mechanical properties of suspension plasma sprayed hydroxyapatite coatings submitted to simulated body fluid

Home synthesized (HA) powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto titanium substrate. The deposition process was optimized and the resulting coatings were soaked in simulated body fluid (SBF) for the periods of 3, 7, 14, 28, and 60 days at controlled temperature of 37 °C. The microstructural research enabled to find in the as-sprayed deposits two characteristic zones: (i) dense zone corresponding to the lamellas, observed usually in thermally sprayed coatings; (ii) sintered zone containing fine hydroxyapatite grains corresponding to the fine solids from initial suspension. The sintered zone disappears after soaking in SBF and the pores get filled by the reprecipitated calcium phosphates. The adhesion of the soaked coatings to the substrate was characterized by the critical load in the scratch test and was about 10 to 12 N. The Young modules of the coatings were determined with help of depth-sensing indentation test by the use of the technique developed by Oliver and Pharr. The modules were not depending on the time of soaking and their mean values were 15.6 and 28.4 GPa, depending on the coating operational parameters. The scratch test enables to determine the hardness of the coatings, which remained fairly constant during the time of soaking in the range of 3 to 5 GPa. This hardness was compared to that the Martens microhardness which doubled with time of soaking to reach up to 1 GPa.