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1
Galipeau, James, und George Slama. „Characterization and Reliability Testing on an LTCC Transformer Operable to 250 °C“. Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2012, HITEC (01.01.2012): 000354–60. http://dx.doi.org/10.4071/hitec-2012-tha24.
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Environments prone to vibration and shocks can cause premature failure in small wire-wound transformers due to cracked cores and broken wires. These problems are only exacerbated by temperatures exceeding 200 °C where the heat causes organic compounds to age rapidly. As more electronics are used in harsh, high temperature environments, high reliability, compact transformers for use in power, filtering, and isolation applications are needed. To address this need monolithic low-temperature co-fired ceramic transformers were developed. In this work transformers were made from a low-temperature, co-fire compatible, ferrite with a Curie temperature of 350 °C. The transformers were first subjected to a 2,000 hour life test at 250 °C in which the transformer was used to charge a load capacitor once every two seconds. The inductance, resistance, core loss, and saturation flux density of the transformers were measured at various temperatures. Additional testing focused on the effect of temperature on the device's frequency profile and performance changes under thermal cycling.
2
Tokarev, Mikhail. „A Double-Bed Adsorptive Heat Transformer for Upgrading Ambient Heat: Design and First Tests“. Energies 12, Nr. 21 (23.10.2019): 4037. http://dx.doi.org/10.3390/en12214037.
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A full scale lab prototype of an adsorptive heat transformer (AHT), consisting of two adsorbers, an evaporator, and a condenser, was designed and tested in subsequent cycles of heat upgrading. The composite LiCl/SiO2 was used as an adsorbent with methanol as an adsorbtive substance under boundary temperatures of TL/TM/TH = −30/20/30 °C. Preliminary experiments demonstrated the feasibility of the tested AHT in continuous heat generation, with specific power output of 520 W/kg over 1–1.5 h steady-state cycling. The formal and experimental thermal efficiency of the tested rig were found to be 0.5 and 0.44, respectively. Although the low potential heat to be upgraded was available for free from a natural source, the electric efficiency of the prototype was found to be as high as 4.4, which demonstrates the promising potential of the “heat from cold” concept. Recommendations for further improvements are also outlined and discussed in this paper.
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Gaynes, Michael, Timothy Chainer, Edward Yarmchuk, John Torok, David Edwards, David Olson und Katie Pizzolato. „Using In situ Capacitance Measurements to Monitor the Stability of Thermal Interface Materials in Complex PCB Assemblies“. International Symposium on Microelectronics 2010, Nr. 1 (01.01.2010): 000450–57. http://dx.doi.org/10.4071/isom-2010-wa3-paper4.
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A thermal solution for an array of voltage transformer modules which are cooled by a large area, common aluminum heat spreader for a high end server was evaluated using an in situ, capacitive bond line thermal measurement technique. The method measures the capacitance of a non-electrically conducting thermal interface material (TIM) between the electronic module and heat spreader to quantify the TIM bond line effective thickness during assembly and operation. The thermal resistance of the TIM has the same geometric dependence as the inverse of capacitance, therefore, the capacitive technique also provided a monitor of the thermal performance of the interface. This technique was applied to measure the bond line in real time during the assembly of the heat spreader to an array of 37 modules mounted on a printed circuit board. The results showed that the target bond lines were not achieved by application of a constant force alone on the heat spreader, and guided an improved assembly process. The mechanical motion of the TIM was monitored in situ during thermal cycling and found to fluctuate systematically from the hot to cold portions of the thermal cycle, either compressing or stretching the TIM respectively. The capacitive bond line trend showed thermal interface degradation vs. cycle count for several modules which was confirmed by disassembly and visual inspection. Areas of depleted TIM ranged as high as 25% of the module area. Several design and material changes were shown to improve the TIM stability. Power cycling tests were run in parallel to the thermal cycle tests to help relate the results to field performance. The capacitance technique enabled the development and verification of a thermal solution for a complex mechanical system early in the development cycle.
4
Hisada, Shota, Mitsuhiro Matsuda, Minoru Nishida, Carlo Biffi und Ausonio Tuissi. „Microstructure and Martensitic Transformation Behavior in Thermal Cycled Equiatomic CuZr Shape Memory Alloy“. Metals 9, Nr. 5 (18.05.2019): 580. http://dx.doi.org/10.3390/met9050580.
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Equiatomic CuZr alloy undergoes a martensitic transformation from the B2 parent phase to martensitic phases (P21/m and Cm) below 150 °C. We clarified the effect of the thermal cycling on the morphology and crystallography of martensite in equiatomic CuZr alloy using a transmission electron microscopy. The 10th cycled specimens consisted of different multiple structures at the maximum temperature of differential scanning calorimetry (DSC) measurement −400 °C and 500 °C, respectively. At the maximum temperature 400 °C of DSC measurement, it is composed of the fine plate-like variants, and a lamellar eutectoid structure consisting of Cu10Zr7 and CuZr2 phases on the martensitic variant. Concerning the maximum temperature of 500 °C of DSC measurement, it is observed the martensitic structure and the lamellar structure in which the martensitic phase was completely eutectoid transformed. The formation of this lamellar eutectoid structure, due to thermal cycling leads to the shift of forward and reverse transformation peaks to low and high temperature side. In addition, new forward and reverse transformation peaks indicating a new transformation appeared by thermal cycling, and the peaks remained around −20 °C. This new martensitic transformation behavior is also discussed.
5
Daróczi, Lajos, Tarek El Rasasi und Dezső L. Beke. „Effect of Partial Thermal Cycles on Non-Chemical Free Energy Contributions in Polycrystalline Cu-Al-Be Shape Memory Alloy“. Materials Science Forum 738-739 (Januar 2013): 38–45. http://dx.doi.org/10.4028/www.scientific.net/msf.738-739.38.
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Abstract. Thermoelasic martensitic transformations are controlled by the local equilibrium of chemical and non-chemical free energy contributions (D and E being the dissipative and elastic energies, respectively). The derivatives of non-chemical free energies ( ) as a function of the transformed martensite fraction (ξ) can be expressed from the experimental data obtained from the temperature-elongation, temperature-resistance, etc hysteresis loops. This method, developed in our laboratory, was used for the investigation of non complete, partial thermoelastic transformation cycles. In the first set of experiments the subsequent cycles were started below the Mf temperature and the maximum temperature was decreased gradually from a value above Af (series U). In the second (L) set the cycles were started above the Af and the minimum temperature was gradually increased from a value below Mf. In the third (UL) set the minor loops were positioned into the centre of the two phase region (i.e. the cycling was made with an increasing T temperature interval with T0.5 and <0.5, respectively. On the other hand the d() functions show a maximum at about the central point of the sub-cycles, and deviate considerably from the d() function obtained from the full cycles. This is also reflected in the dependence of the integral value of the dissipative energy, D(): its value for the partial loops is lower than the dissipative energy calculated from the full cycle for the same transformed fraction interval. An opposite tendency (i.e. higher values for the partial loops) was obtained for the integral value of the elastic energy, E. The relative values of the dissipated energies, D, (calculated from the areas of the minor loops and normalized to the area of the major loop) are not very sensitive to the details of the cycling process, i.e. they are very similar for all sets.
6
Sitepu, H., Heinz Günter Brokmeier, Daniel Chateigner und J. P. Wright. „Crystallographic Phase Composition and Structural Analysis of Ti-Ni-Fe Shape Memory Alloy by Synchrotron Diffraction“. Solid State Phenomena 105 (Juli 2005): 139–44. http://dx.doi.org/10.4028/www.scientific.net/ssp.105.139.
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The preferred crystallographic orientation (i.e. texture) and the non-transformed austenite can cause serious systematic errors in the structural study of the R-phase in 50.75at.%Ti- 47.75at.%Ni-1.50at.%Fe (hereafter referred to as Ti-Ni-Fe ternary) shape memory alloy. The crystal structure refinement of R-phase synchrotron high resolution powder diffraction (SRD) data using Rietveld refinement with generalized spherical harmonic (GSH) description for preferred orientation correction showed that the sample consists of minor cubic phase and the space group was 3 P [1]. The objective of the present paper is to study the crystallographic phase composition and crystal structure refinement of SRD data of trigonal R-phase martensite and monoclinic (B19¢) martensite in Ti-Ni-Fe ternary alloy during thermal cycling using the GSH description.
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Wertz, Markus, Florian Fuchs, Hieronymus Hoelzig, Julia Maria Wertz, Gert Kloess, Sebastian Hahnel, Martin Rosentritt und Andreas Koenig. „The Influence of Surface Preparation, Chewing Simulation, and Thermal Cycling on the Phase Composition of Dental Zirconia“. Materials 14, Nr. 9 (22.04.2021): 2133. http://dx.doi.org/10.3390/ma14092133.
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The effect of dental technical tools on the phase composition and roughness of 3/4/5 yttria-stabilized tetragonal zirconia polycrystalline (3y-/4y-/5y-TZP) for application in prosthetic dentistry was investigated. Additionally, the X-ray diffraction methods of Garvie-Nicholson and Rietveld were compared in a dental restoration context. Seven plates from two manufacturers, each fabricated from commercially available zirconia (3/4/5 mol%) for application as dental restorative material, were stressed by different dental technical tools used for grinding and polishing, as well as by chewing simulation and thermocycling. All specimens were examined via laser microscopy (surface roughness) and X-ray diffraction (DIN EN ISO 13356 and the Rietveld method). As a result, the monoclinic phase fraction was halved by grinding for the 3y-TZP and transformed entirely into one of the tetragonal phases by polishing/chewing for all specimens. The tetragonal phase t is preferred for an yttria content of 3 mol% and phase t″ for 5 mol%. Mechanical stress, such as polishing or grinding, does not trigger low-temperature degradation (LTD), but it fosters a phase transformation from monoclinic to tetragonal under certain conditions. This may increase the translucency and deteriorate the mechanical properties to some extent.
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Hu, Tian Qi, Hong Tao Chen und Ming Yu Li. „Fabrication of Cu@Sn Core-Shell Structured Particles and the Application in High Remelting Temperature Bonding“. Materials Science Forum 878 (November 2016): 3–7. http://dx.doi.org/10.4028/www.scientific.net/msf.878.3.
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A novel solder bonding material for high-temperature applications based on Cu@Sn core-shell structured particles was developed, and the fabricated Cu@Sn particles were compressed into preforms for die attachment. The reflow temperature for this bonding material could reached as low as 260°C due to the low melting temperature of the outer Sn layer. However, after reflow soldering, the resulting interconnections can withstand a high temperature of at least 415°C, outer Sn layer completely transformed into Cu-Sn intermetallic compounds (IMCs) with high remelting temperatures. The formed bondlines exhibit good electrical conductivity due to the low porosity and the embedded Cu particles in the interconnections. Furthermore, the interconnections also exhibit excellent reliability under thermal shock cycling from-55°C to 200°C. This die attach material is suitable for power devices operating under high temperatures or other harsh environments.
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Ren, Y., H. Zhou, X. Wang, Q. W. Liu, X. D. Hou und G. F. Zhang. „Study of the Structure and Properties of ZnS Utilized in a Fluorescence Biosensor“. Stem Cells International 2021 (28.08.2021): 1–6. http://dx.doi.org/10.1155/2021/7067146.
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ZnS materials have been widely used in fluorescence biosensors to characterize different types of stem cells due to their excellent fluorescence effect. In this study, ZnS was prepared by vulcanizing nano-Zn particles synthesized using a DC arc plasma. The composition and structure of the ZnS materials were studied by X-ray diffraction (XRD), and their functional group information and optical properties were investigated by using IR spectrophotometry and UV-vis spectrophotometry. It has been found that the synthesized materials consist of Zn, cubic ZnS, and hexagonal ZnS according to the vulcanization parameters. Crystalline ZnS was gradually transformed from a cubic to a hexagonal structure, and the cycling properties first increase, then decrease with increasing sulfurization temperature. There is an optimal curing temperature giving the best cycling performance and specific capacity: the material sulfurized thereat mainly consists of cubic β-ZnS phase with a small quantity of Zn and hexagonal α-ZnS. The cubic phase ZnS has better conductivity than hexagonal ZnS, as evinced by electrochemical impedance spectroscopy (EIS). The ZnS (as prepared) shows board absorption, which can be used in fluorescence biosensors in cell imaging systems.
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Islam, Atikul, Ally J. Su, Zih-Ming Zeng, Pin Ju Chueh und Ming-Hung Lin. „Capsaicin Targets tNOX (ENOX2) to Inhibit G1 Cyclin/CDK Complex, as Assessed by the Cellular Thermal Shift Assay (CETSA)“. Cells 8, Nr. 10 (18.10.2019): 1275. http://dx.doi.org/10.3390/cells8101275.
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Capsaicin (8-methyl-N-vanillyl-6-noneamide), which is an active component in red chili peppers, is used as a chemopreventive agent that shows favorable cytotoxicity against cancer cells. Accumulating evidence indicates that capsaicin preferentially inhibits a tumor-associated NADH oxidase (tNOX, ENOX2) that is ubiquitously expressed in cancer but not in non-transformed cells. This attenuates cancer cell growth by inducing apoptosis. The capsaicin-mediated inhibition of tNOX was recently shown to prolong the cell cycle. However, the molecular events underlying this regulation have not yet been investigated. In the present study, we used a cellular thermal shift assay (CETSA) to detect “target engagement” of capsaicin and its consequent impact on cell cycle progression. Our results indicated that capsaicin engaged with tNOX and triggered the proteasomal degradation of tNOX, which leads to the inhibition of NAD+-dependent SIRT1 deacetylase. Ultimately, the acetylation levels of c-Myc and p53 were enhanced, which suppressed the activation of G1 cyclin/Cyclin-dependent kinase complexes and triggered cell cycle arrest in cancer cells. The results obtained when tNOX was overexpressed in non-cancer cells validated its importance in cell cycle progression. These findings provide the first molecular insights into the regulatory role of tNOX and the anti-proliferative property of capsaicin in regulating the cell cycle of bladder cancer cells.
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Enzmann, F., M. M. Miedaner, M. Kersten, N. von Blohn, K. Diehl, S. Borrmann, M. Stampanoni, M. Ammann und T. Huthwelker. „3-D imaging and quantification of graupel porosity by synchrotron-based micro-tomography“. Atmospheric Measurement Techniques 4, Nr. 10 (19.10.2011): 2225–34. http://dx.doi.org/10.5194/amt-4-2225-2011.
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Abstract. The air bubble structure is an important parameter to determine the radiation properties of graupel and hailstones. For 3-D imaging of this structure at micron resolution, a cryo-stage was developed. This stage was used at the tomography beamline of the Swiss Light Source (SLS) synchrotron facility. The cryo-stage setup provides for the first time 3-D-data on the individual pore morphology of ice particles down to infrared wavelength resolution. In the present study, both sub-mm size natural and artificial ice particles rimed in a wind tunnel were investigated. In the natural rimed ice particles, Y-shaped air-filled closed pores were found. When kept for half an hour at −8 °C, this morphology transformed into smaller and more rounded voids well known from literature. Therefore, these round structures seem to represent an artificial rather than in situ pore structure, in contrast to the observed y-shaped structures found in the natural ice particles. Hence, for morphological studies on natural ice samples, special care must be taken to minimize any thermal cycling between sampling and measurement, with least artifact production at liquid nitrogen temperatures.
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Yang, Gon Seung, Jong Kook Lee, Woo Yang Jang, Soon Jong Jeong und Kanryu Inoue. „Effect of Aging and Microstructure on Mechanical Rolling CuAlNi Shape Memory Alloy“. Materials Science Forum 539-543 (März 2007): 3326–31. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.3326.
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CuAlNi shape memory alloy with Cu-13.5Al-4.5Ni(wt%) composition was prepared by cross-rolling method and the aging effect, phase transformation characteristics, microstructural variation were investigated. Transformation temperature was greatly increased in aged specimens at 250°C. Transformation temperature was not changed after the second reversed transformation, and Ms point was same in most specimens with third reversed transformation cycle. The variation of Ms point was not seen with aging at 100°C, but it was decreased with aging at 250°C. Transformation temperatures appear to be constant, to an measurable extent, in specimens prepared by both hotrolling and cross-rolling at 900°C. Plate shaped-specimen with the thickness of about 1mm was prepared by cross-rolling treatment at 350°C. The transformation temperatures did not change after the second transformation-reverse transformation cycling, and specially transformation start temperature was the same in most specimens experiencing third thermal cycle and thereafter. Undesirable tweed-like structure was observed in 250°C-aged specimen after a cross-rolling at 350°C. On aging the specimen prepared by cross-rolling, G.P zone was formed easier than that of γ2 phase. This phase was transformed to plate-like θ phase during aging.
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Coster, Paul, Craig Henderson, Steven Hunter, William Marshall und Colin Pulham. „Explosives at Extreme Conditions: Polymorphism of 2,4-Dinitroanisole“. Acta Crystallographica Section A Foundations and Advances 70, a1 (05.08.2014): C896. http://dx.doi.org/10.1107/s2053273314091037.
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2,4-dinitroanisole (DNAN) is an energetic material, developed as an insensitive replacement for TNT in melt-cast explosive formulations. While DNAN-based formulations demonstrate greatly reduced sensitivity to accidental initiation compared to those using TNT, issues remain with the replacement of TNT with DNAN. For instance, DNAN based formulations have demonstrated catastrophic levels of irreversible growth during heat-cycling, with volume increases of up to 15% reported. [1] In order to investigate the role of polymorphism in the irreversible growth of DNAN, high-pressure and variable-temperature neutron and x-ray diffraction studies have been performed. Two polymorphs of DNAN have been found to exist at ambient temperature and pressure, the thermodynamic form, DNAN-I, and the kinetic form, DNAN-II.[2,3] The phase diagrams of both form-I and -II of DNAN have been explored for the first time. In the case of DNAN-II, two high-pressure phase transitions were found. DNAN-II initially transformed to DNAN-III, which at higher pressures transformed to DNAN-IV. In addition, variable temperature studies demonstrated that the DNAN-II to DNAN-III transition also occurs when DNAN-II is cooled below room temperature. The thermal expansion of the DNAN-II/III lattice was investigated from 150K to 363K, demonstrating that an abrupt change in the thermal behaviour of lattice parameters occurs at the DNAN-II/III transition. From these combined crystallographic studies, the structure of DNAN-III has been solved, showing it is closely related to DNAN-II. In the case of DNAN-I, high-pressure neutron powder diffraction studies demonstrated that it transforms to a new form (DNAN-V) that is distinct from DNAN-II,-III or -IV. Rietveld refinement of the high-pressure DNAN-I data also determined that the material exhibits negative linear compressibility, which is of interest given the use of DNAN as a shock-insensitive energetic material. Comparison of the behaviour of DNAN-I and –II under variable temperature and high-pressure conditions indicates that the kinetic form, DNAN-II, is the denser phase under all conditions studied. This work highlights the importance of crystallographic techniques in order to understand the polymorphism of energetic materials.
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Park, Sanghyuk, Kwangho Park, Ji-Seop Shin, Gyeongbin Ko, Wooseok Kim, Jun-Young Park und Kyungjung Kwon. „Utilizing the Intrinsic Thermal Instability of Swedenborgite Structured YBaCo4O7+δ as an Opportunity for Material Engineering in Lithium-Ion Batteries by Er and Ga Co-Doping Processes“. Materials 14, Nr. 16 (14.08.2021): 4565. http://dx.doi.org/10.3390/ma14164565.
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We firstly introduce Er and Ga co-doped swedenborgite-structured YBaCo4O7+δ (YBC) as a cathode-active material in lithium-ion batteries (LIBs), aiming at converting the phase instability of YBC at high temperatures into a strategic way of enhancing the structural stability of layered cathode-active materials. Our recent publication reported that Y0.8Er0.2BaCo3.2Ga0.8O7+δ (YEBCG) showed excellent phase stability compared to YBC in a fuel cell operating condition. By contrast, the feasibility of the LiCoO2 (LCO) phase, which is derived from swedenborgite-structured YBC-based materials, as a LIB cathode-active material is investigated and the effects of co-doping with the Er and Ga ions on the structural and electrochemical properties of Li-intercalated YBC are systemically studied. The intrinsic swedenborgite structure of YBC-based materials with tetrahedrally coordinated Co2+/Co3+ are partially transformed into octahedrally coordinated Co3+, resulting in the formation of an LCO layered structure with a space group of R-3m that can work as a Li-ion migration path. Li-intercalated YEBCG (Li[YEBCG]) shows effective suppression of structural phase transition during cycling, leading to the enhancement of LIB performance in Coulombic efficiency, capacity retention, and rate capability. The galvanostatic intermittent titration technique, cyclic voltammetry and electrochemical impedance spectroscopy are performed to elucidate the enhanced phase stability of Li[YEBCG].
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Wang, Yunke, Guozheng Zha, Yenan Zhang, Feng Liang, Yongnian Dai, Yaochun Yao und Lingxin Kong. „Study of the Composite Modified Positive Electrode between NCM811 and V2O5 Materials in Li-Ion Cells“. Nano 16, Nr. 03 (16.02.2021): 2150032. http://dx.doi.org/10.1142/s1793292021500326.
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The possibility of combining the promising cathode material LiNi[Formula: see text]Co[Formula: see text]Mn[Formula: see text]O2 (NCM811) with V2O5 material with excellent conductivity as a composite cathode material for lithium-ion batteries was discussed. The fact that the mechanical and physical mixing process did not change the original structure of both NCM811 and V2O5 was confirmed by XRD. SEM and TEM show that the V2O5 particles were attached to the surface of NCM811 and filled the gaps between NCM811 particles. Furthermore, TEM image after cycling reveals that the gathering of Nano-plates V2O5 on the surface of spherical-like NCM811 particles transformed to coating layers ([Formula: see text][Formula: see text]nm) after reacting with lithium, which leads to the increase of impedance, while the stable coating layer would protect the active material from being corroded by the decomposition products of the electrolyte and prevent the collapse of the microstructure to maintain the stability of Li[Formula: see text] mobility channels. The sample exhibited an attractive first discharge capacity of 214[Formula: see text]mAh[Formula: see text]g[Formula: see text] with the 94.7% initial columbic efficiency and a higher capacity retention when the mass ratio of V2O5 is 15[Formula: see text]wt.%. Thus, the reversibility of reaction at low voltage 2.0[Formula: see text]V and high temperature have been enhanced after the modification. This is undoubtedly the necessary condition to improve the security of electrolyte thermal decomposition. Our work will provide some guidance for the future development of high temperature Li-ion batteries.
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Shamji, Mohammed F., Odelia Ghodsizadeh, Allan H. Friedman, William J. Richardson, Ashutosh Chilkoti und Lori A. Setton. „Development of a thermally responsive peptide for sustained deliver of solyble TNF receptor II to attenuate inflammatory events associated with radiculopathys“. Clinical & Investigative Medicine 30, Nr. 4 (01.08.2007): 94. http://dx.doi.org/10.25011/cim.v30i4.2873.
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Background: Tumor necrosis factor alpha (TNFα) is a cytokine that may mediate inflammatory histopathology of the dorsal root ganglion following lumbar disc herniation.1 Soluble TNF receptor II (sTNFRII) competitively binds TNFa with clinical value for painful radiculopathy.2 Bioactive peptides expressed with elastin-like polypeptides (ELP) fusion partners gain a thermally responsive domain, by which they can undergo hydrophobic collapse and separate from solution to aggregate at physiological temperatures.3 Protein release from such a depot may locally sustain drug presence, an effect demonstrated for non-fusion ELP after intra-articular injection.4
Methods: We expressed sTNFRII fused to ELP to demonstrate potential bidomain functionality.
Protein Expression. A gene encoding ELP-(VPGVG)60 was subcloned adjacent to the sTNFRII and transformed into E.coli for expression.5 Protein Safety. Endotoxin content of purified fusion protein was evaluated using a limulus amebocyte lysate endpoint assay and compared to non-fusion ELP using a two-tailed Student’s t-test. Thermal Responsiveness. Dynamic light scattering evaluated the inverse thermal phase transition behaviour of ELP-sTNFRII, and absorbance spectrophotometry quantified the in vitro depot release at 37°C. Fusion Domain Function. Anti-TNFα bioactivity was assessed by the in vitro inhibition of TNFα-induced glutamate production by microglia. Single-factor ANOVA analyzed treatment differences for ELP-sTNFRII, commercial sTNFRII (positive control), and non-fusion ELP (negative control).
A 44 kDa recombinant fusion protein was expressed from E. coli and purified by inverse transition cycling.
Results: Measured endotoxin content for ELP-sTNFRII was comparable to ELP alone (p < 0.01), well below FDA levels for biomedical implants. The fusion protein underwent a thermally-induced phase transition and formed observable aggregates of ~240 nm upon heating to physiological temperatures (Tt = 32°C). Slow release was observed from this depot with a time constant of 21 ± 3 hours. The fusion protein demonstrated anti-TNFα activity in vitro by attenuating TNFα-induced microglial glutamate production, albeit requiring a greater concentration than the free antagonist to achieve the same effect.(p < 0.01).
Conclusion: Fusion of a sTNFRII protein to an ELP can serve to generate a thermally-induced drug depot that may sustain anti-cytokine activity of agents delivered locally to a nerve region. Further directions may involve studying in vivo biodistribution after perineural delivery of ELP and in vivo disease modifying activity of this agent.
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Deschaseaux, Elisabeth, James O'Brien, Nachshon Siboni, Katherina Petrou und Justin R. Seymour. „Shifts in dimethylated sulfur concentrations and microbiome composition in the red-tide causing dinoflagellate <i>Alexandrium minutum</i> during a simulated marine heatwave“. Biogeosciences 16, Nr. 22 (19.11.2019): 4377–91. http://dx.doi.org/10.5194/bg-16-4377-2019.
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Abstract. The biogenic sulfur compounds dimethyl sulfide (DMS), dimethyl sulfoniopropionate (DMSP) and dimethyl sulfoxide (DMSO) are produced and transformed by diverse populations of marine microorganisms and have substantial physiological, ecological and biogeochemical importance spanning organism to global scales. Understanding the production and transformation dynamics of these compounds under shifting environmental conditions is important for predicting their roles in a changing ocean. Here, we report the physiological and biochemical response of a robust strain of Alexandrium minutum, a dinoflagellate with the highest reported intracellular DMSP content, exposed to a 6 d increase in temperature mimicking mild and extreme coastal marine heatwave conditions (+4 and +12 ∘C). Under mild temperature increases (+4 ∘C), A. minutum growth was enhanced, with no measurable physiological stress response. However, under a very acute increase in temperature (+12 ∘C) triggering thermal stress, A. minutum growth declined, photosynthetic efficiency (FV∕FM) was impaired, and enhanced oxidative stress was observed. These physiological responses indicative of thermal stress were accompanied by increased DMS and DMSO concentrations followed by decreased DMSP concentration. At this temperature extreme, we observed a cascading stress response in A. minutum, which was initiated 6 h after the start of the experiment by a spike in DMS and DMSO concentrations and a rapid decrease in FV∕FM. This was followed by an increase in reactive oxygen species (ROS) and an abrupt decline in DMS and DMSO on day 2 of the experiment. A subsequent decrease in DMSP coupled with a decline in the growth rate of both A. minutum and its associated total bacterial assemblage coincided with a shift in the composition of the A. minutum microbiome. Specifically, an increase in the relative abundance of the operational taxonomic units (OTUs) matching Oceanicaulis (17.0 %), Phycisphaeraceae SM1A02 (8.8 %) and Balneola (4.9 %) as well as a decreased relative abundance of Maribacter (24.4 %), Marinoscillum (4.7 %) and Seohaeicola (2.7 %) were primarily responsible for differences in microbiome structure observed between temperature treatments. These shifts in microbiome structure are likely to have been driven by either the temperature itself, the changing physiological state of A. minutum cells, shifts in biogenic sulfur concentrations, the presence of other solutes, or a combination of all. Nevertheless, we suggest that these results point to the significant effect of extreme heatwaves on the physiology, growth and microbiome composition of the red-tide causing dinoflagellate A. minutum, as well as potential implications for biogenic sulfur cycling processes and marine DMS emissions.
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Ozdemir, Niyazi, Furkan Sarsilmaz und Nuri Orhan. „The Effect of Cementite Size and Morphology on the Abrasive Wear Behavior of UHC Steel“. Journal of Tribology 130, Nr. 2 (13.03.2008). http://dx.doi.org/10.1115/1.2842238.
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In this study, the abrasive wear behavior of a grain refined hypereutectoid carbon steel containing 1.2% C, 4% Al, 0.20% Mo, and 0.1% Ti was investigated experimentally. Thermal cycles were applied to all specimens about ten times to obtain a fine-grained structure and to gain more softness structures, such as spheroidized cementite for these steels. After every thermal cycle, the microstructures of specimens were examined by scanning electron microscopy to determine the transformation mechanism of structure. Microstructure analyses showed that size of cementite decreased as a function of heat treatment cycle. With the increase of heat treatment cycle, the grain size of cementite in all specimens started to decrease. As a consequence, these cementite islands transformed to spherical cementite having an average grain size of 5μm. In addition, the wear test results indicated a correspondence between wear rate and thermal cycling. However, the hardness values decreased with increasing heat treatment cycle.
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Burra, K. G., A. K. Gupta und S. Kerdsuwan. „Isothermal Splitting of CO2 to CO Using Cobalt-Ferrite Redox Looping“. Journal of Energy Resources Technology 143, Nr. 3 (27.08.2020). http://dx.doi.org/10.1115/1.4048077.
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Abstract Rising atmospheric CO2 levels from significant imbalance between carbon emissions from fossil fuel utilization, especially for energy and chemicals, and natural carbon sequestration rates is known to drive-up the global temperatures and associated catastrophic climate changes, such as rising mean sea level, glacial melting, and extinction of ecosystems. Carbon capture and utilization techniques are necessary for transition from fossil fuel infrastructure to renewable energy resources to help delay the dangers of reaching to the point of positive feedback between carbon emissions and climate change which can drive terrestrial conditions to uninhabitable levels. CO2 captured from the atmosphere directly or from flue gases of a power plant can be recycled and transformed to CO and syngas for use as energy and value-added chemicals. Utilizing renewable energy resources to drive CO2 conversion to CO via thermochemical redox looping can provide a carbon negative renewable energy conversion pathway for sustainable energy production as well as value-added products. Substituted ferrites such as Co-ferrite, Mn-ferrite were found to be promising materials to aid the conversion of CO2 to CO at lower reduction temperatures. Furthermore, the conversion of these materials in the presence of Al2O3 provided hercynite cycling, which further lowered the reduction temperature. In this paper, Co-ferrite and Co-ferrite-alumina prepared via co-precipitation were investigated to understand their potential as oxygen carriers for CO2 conversion under isothermal redox looping. Isothermal reduction looping provided improved feasibility in redox conversion since it avoids the need for temperature swinging which improves thermal efficiency. These efforts alleviate the energy losses in heat recovery while also reducing thermal stresses on both the materials and the reactor. Lab-scale testing was carried out at 1673 K on these materials for extended periods and multiple cycles to gain insights into cyclic performance and the feasibility of sintering, which is a common issue in iron oxide-based oxygen carriers. Cobalt doping provided with lowering of reduction temperature requirement at the cost of oxidation thermodynamic spontaneity that required increased oxidation temperature. At the concentrations examined, these opposing phenomena made isothermal redox operation feasible by providing high CO yields comparable with oxygen carriers in the literature, which were operated at different temperatures for reduction and oxidation. Significantly high CO yields (∼750 µmol/g) were obtained from Co-ferrite isothermal redox looping. Co-ferrite-alumina provided lower CO yields compared with Co-ferrite. The oxygen storage was similar to those reported in the literature on isothermal H2O splitting, but with improved morphological stability at high temperature, especially compared with ferrite. This pathway of oxygen carrier development is considered suitable with further requirement in optimization for scaling of renewable CO2 conversion into valuable products.