Abstract The adoption of Single-phase Liquid Immersion Cooling (Sp-LIC) for Information Technology equipment provides an excellent cooling platform coupled with significant energy savings. There are, however, very limited studies related to the reliability of such cooling technology. The Accelerated Thermal Cycling (ATC) test given ATC JEDEC is relevant just for air cooling but there is no such standard for immersion cooling. The ASTM benchmark D3455 with some appropriate adjustments was adopted to test the material compatibility because of the air and dielectric fluid differences in the heat capacitance property and corresponding ramp rate during thermal cycling. For this study, accelerated thermal degradation of the printed circuit board (PCB), passive components, and fiber optic cables submerged in air, white mineral oil, and synthetic fluid at a hoisted temperature of 45C and 35% humidity is undertaken. This paper serves multiple purposes including designing experiments, testing and evaluating material compatibility of PCB, passive components, and optical fibers in different hydrocarbon oils for single-phase immersion cooling. Samples of different materials were immersed in different hydrocarbon oils and air and kept in an environmental chamber at 45C for a total of 288 hours. Samples were then evaluated for their mechanical and electrical properties using Dynamic Mechanical Analyzer (DMA) and a multimeter, respectively. The cross-sections of some samples were also investigated for their structural integrity using SEM. The literature gathered on the subject and quantifiable data gathered by the authors provide the primary basis for this research document.
more »
« less
Modulating Photochemical Properties to Enhance the Stability of Electronically Dimmable Eye Protection Devices †
The study evaluates compatibility of stabilizers with dye doped liquid crystal (LC) scaffolds that are used in electronically dimmable materials. The photodegradation of the materials was investigated and suitable stabilizers were evaluated to slow the degradation process. Various types of benzotriazole-based stabilizers were evaluated for stabilizing the liquid crystals. Based on spin trapping experiments, radicals generated upon UV exposure is likely responsible for the degradation of the system. The radical generation is competitively inhibited by the addition of stabilizers.
more »
« less
- Award ID(s):
- 1900541
- NSF-PAR ID:
- 10412731
- Date Published:
- Journal Name:
- Photochemistry and Photobiology
- ISSN:
- 0031-8655
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
more » « less
Abstract Thermal desorption/degradation with an atmospheric solids analysis probe (ASAP) and ion mobility (IM) separation are coupled with mass spectrometry (MS) analysis and tandem mass spectrometry (MS/MS) fragmentation to characterize thermoplastic elastomers. The compounds investigated, which are used in the manufacture of a wide variety of packaging materials, are mainly composed of thermoplastic copolymers, but also contain additional chemicals (“additives”), like antioxidants and UV stabilizers, for enhancement of their properties or protection from degradation. The traditional method for analyzing such complex mixtures is vacuum pyrolysis followed by electron or chemical ionization mass spectrometry, often after gas chromatography separation. Here, an alternative, faster approach, involving mild degradation at atmospheric pressure (ASAP) and subsequent characterization of the desorbates and pyrolyzates by IM‐MS, and if needed, MS/MS is presented. Such multidimensional dispersion considerably simplifies the resulting spectra, permitting the conclusive separation, characterization, and classification of the multicomponent materials examined.
-
more » « less
Abstract BACKGROUND A major problem in the orange industry is ‘delayed’ bitterness, which is caused by limonin, a bitter compound developing from its non‐bitter precursor limonoate A‐ring lactone (LARL) during and after extraction of orange juice. The glucosidation of LARL by limonoid UDP‐glucosyltransferase (LGT) to form non‐bitter glycosyl‐limonin during orange maturation has been demonstrated as a natural way to debitter by preventing the formation of limonin.
RESULT Here, the debittering potential of heterogeneously expressed glucosyltransferase, maltose‐binding protein (MBP) fused to
cu GT fromCitrus unishiu Marc (MBP‐cu GT), which was previously regarded as LGT, was evaluated. A liquid chromatography – mass spectrometry (LC–MS) method was established to determine the concentration of limonin and its derivatives. The protocols to obtain its potential substrates, LARL and limonoate (limonin with both A and D ring open), were also developed. Surprisingly, MBP‐cu GT did not exhibit any detectable effect on limonin degradation when Navel orange juice was used as the substrate; MBP‐cu GT was unable to biotransform either LARL or limonoate as purified substrates. However, it was found that MBP‐cu GT displayed a broad activity spectrum towards flavonoids, confirming that the enzyme produced was active under the conditions evaluatedin vitro .CONCLUSION Our results based on LC–MS demonstrated that
cu GT functionality was incorrectly identified. Its active substrates, including various flavonoids but not limonoids, highlight the need for further efforts to identify the enzyme responsible for LGT activity to develop biotechnology‐based approaches for producing orange juice from varietals that traditionally have a delayed bitterness. © 2020 Society of Chemical Industry -
more » « less
Abstract Aluminyl anions are low‐valent, anionic, and carbenoid aluminum species commonly found stabilized with potassium cations from the reaction of Al‐halogen precursors and alkali compounds. These systems are very reactive toward the activation of
σ ‐bonds and in reactions with electrophiles. Various research groups have detected that the potassium atoms play a stabilization role via electrostatic and cationinteractions with nearby (aromatic)‐carbocyclic rings from both the ligand and from the reaction with unsaturated substrates. Since stabilizing K⋯H bonds are witnessed in the activation of this class of molecules, we aim to unveil the role of these metals in the activation of the smaller and less polarizable H2molecule, together with a comprehensive characterization of the reaction mechanism. In this work, the activation of H2utilizing a NON‐xanthene‐Al dimer, [K{Al(NON)}]2( D ) and monomeric, [Al(NON)]−(M ) complexes are studied using density functional theory and high‐level coupled‐cluster theory to reveal the potential role of K+atoms during the activation of this gas. Furthermore, we aim to reveal whetherD is more reactive thanM (or vice versa), or if complicity between the two monomer units exits within theD complex toward the activation of H2. The results suggest that activation energies using the dimeric and monomeric complexes were found to be very close (around 33 kcal mol−1). However, a partition of activation energies unveiled that the nature of the energy barriers for the monomeric and dimeric complexes are inherently different. The former is dominated by a more substantial distortion of the reactants (and increased interaction energies between them). Interestingly, during the oxidative addition, the distortion of the Al complex is minimal, while H2distorts the most, usually over 0.77. Overall, it is found here that electrostatic and induction energies between the complexes and H2are the main stabilizing components up to the respective transition states. The results suggest that the K+atoms act as stabilizers of the dimeric structure, and their cooperative role on the reaction mechanism may be negligible, acting as mere spectators in the activation of H2. Cooperation between the two monomers in D is lacking, and therefore the subsequent activation of H2is wholly disengaged. -
In this study, the use of a closo-borate salt as an electrolyte for lithium-ion batteries (LIB) was evaluated in a series of solvent systems. The lithium closo-borate salts are a unique class of halogen-free salts that have the potential to offer some advantages over the halogenated salts currently employed in commercially available LIB due to their chemical and thermal stability. To evaluate this concept, three different solvent systems were prepared with a lithium closo-borate salt to make a liquid electrolyte (propylene carbonate, ethylene carbonate:dimethyl carbonate, and 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide). The closo-borate containing electrolytes were then compared by utilizing them with three different electroactive electrode materials. Their cycle stability and performance at various charge/discharge rates was also investigated. Based on the symmetrical cell and galvanostaic cycling studies it was determined that the carbonate based liquid electrolytes performed better than the ionic liquid electrolyte. This work demonstrates that halogen free closo-borate salts are interesting candidates and worthy of further investigation as lithium salts for LIB.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1111/php.13795
