This article presents the high temperature tensile and creep behaviors of a novel high entropy alloy (HEA). The microstructure of this HEA resembles that of advanced superalloys with a high entropy ...FCC matrix and L1
ordered precipitates, so it is also named as "high entropy superalloy (HESA)". The tensile yield strengths of HESA surpass those of the reported HEAs from room temperature to elevated temperatures; furthermore, its creep resistance at 982 °C can be compared to those of some Ni-based superalloys. Analysis on experimental results indicate that HESA could be strengthened by the low stacking-fault energy of the matrix, high anti-phase boundary energy of the strengthening precipitate, and thermally stable microstructure. Positive misfit between FCC matrix and precipitate has yielded parallel raft microstructure during creep at 982 °C, and the creep curves of HESA were dominated by tertiary creep behavior. To the best of authors' knowledge, this article is the first to present the elevated temperature tensile creep study on full scale specimens of a high entropy alloy, and the potential of HESA for high temperature structural application is discussed.
We report a facile and cost-effective approach to develop self-standing reduced Graphene Oxide (rGO) film based optical sensor and its low-temperature performance analysis where midgap defect states ...play a key role in tuning the crucial sensor parameters. Graphite oxide (GO) is produced by modified Hummers' method and reduced thermally at 250 °C for 1 h in Argon atmosphere to obtain rGO. Self-standing rGO film is prepared via vacuum filtration. The developed film is characterized by HRTEM, FESEM, Raman, and XRD techniques. The developed sensor exhibits highest sensitivity towards 635 nm illumination wavelength, irrespective of the operating temperature. For a given excitation wavelength, photoresponse study at low temperature (123K-303K) reveals inverse relationship between sensitivity and operating temperature. Highest sensitivity of 49.2% is obtained at 123 K for 635 nm laser at power density of 1.4 mW/mm
. Unlike sensitivity, response- and recovery-time demonstrate directly proportional dependence with operating temperature. Power dependent studies establish linear relation between power-density and sensitivity, and a safe limit beyond which sample heating prolongs the recovery time. Wavelength-dependent studies shows that proposed sensor can efficiently operate from visible to near NIR region. To the best of our knowledge such rGO based optical sensor performance at low temperature had not been reported earlier.
Short episodes of high temperature (HT) stress during reproductive stages of development cause significant yield losses in wheat (Triticum aestivum L.). Two independent experiments were conducted to ...quantify the effects of HT during anthesis and grain filling periods on photosynthesis, leaf lipidome, and yield traits in wheat. In experiment I, wheat genotype Seri82 was exposed to optimum temperature (OT; 22/14 °C; day/night) or HT (32/22 °C) for 14 d during anthesis stage. In experiment II, the plants were exposed to OT or HT for 14 d during the grain filling stage. During the HT stress, chlorophyll index, thylakoid membrane damage, stomatal conductance, photosynthetic rate and leaf lipid composition were measured. At maturity, grain yield and its components were quantified.
HT stress during anthesis or grain filling stage decreased photosynthetic rate (17 and 25%, respectively) and grain yield plant
(29 and 44%, respectively), and increased thylakoid membrane damage (61 and 68%, respectively) compared to their respective control (OT). HT stress during anthesis or grain filling stage increased the molar percentage of less unsaturated lipid species 36:5- monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG). However, at grain filling stage, HT stress decreased the molar percentage of more unsaturated lipid species (36:6- MGDG and DGDG). There was a significant positive relationship between photosynthetic rate and grain yield plant
, and a negative relationship between thylakoid membrane damage and photosynthetic rate.
The study suggests that maintaining thylakoid membrane stability, and seed-set per cent and individual grain weight under HT stress can improve the photosynthetic rate and grain yield, respectively.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We present an analysis of the influence of an external magnetic field on renormalons in a self-interacting theory λϕ4. For weak magnetic field region, using an appropriate expansion for the Schwinger ...propagators, we find renormalons as poles on the real axis of the Borel plane, of which the position do not depend on the magnetic field, but where the residues acquire in fact a magnetic dependence. In the strong magnetic limit, working in the lowest Landau level approximation, these new poles are no longer present. We compare the magnetic scenario with previous results in the literature concerning thermal effects on renormalons in this theory.
Individual luminescent nanoparticles enable thermometry with sub-diffraction limited spatial resolution, but potential self-heating effects from high single-particle excitation intensities remain ...largely uninvestigated because thermal models predict negligible self-heating. Here, we report that the common "ratiometric" thermometry signal of individual NaYF
:Yb
,Er
nanoparticles unexpectedly increases with excitation intensity, implying a temperature rise over 50 K if interpreted as thermal. Luminescence lifetime thermometry, which we demonstrate for the first time using individual NaYF
:Yb
,Er
nanoparticles, indicates a similar temperature rise. To resolve this apparent contradiction between model and experiment, we systematically vary the nanoparticle's thermal environment: the substrate thermal conductivity, nanoparticle-substrate contact resistance, and nanoparticle size. The apparent self-heating remains unchanged, demonstrating that this effect is an artifact, not a real temperature rise. Using rate equation modeling, we show that this artifact results from increased radiative and non-radiative relaxation from higher-lying Er
energy levels. This study has important implications for single-particle thermometry.
Numerical study on magnetohydrodynic (MHD) flow and heat transfer of incompressible CNTs-water nanoparticles (single wall carbon and tube (SWCNT) and multiwall cabin nanotube (MWCNT)) as a ...non-Newtonian micropolar dusty fluid influenced by non-linear thermal radiation and joule heating effect over stretching plate are investigated in this paper. The governing equations have been solved by numerical method. Flow and heat transfer for two cases of prescribed heat flux (PHF) and prescribed surface temperature (PST) are analyzed, As a important result have been mentioned to the reduction of velocity profile due to the Lorentz force by increasing magnetic field parameter, the temperature profile increases by increasing radiation parameter, and MWCNT in comparison to the SWCNT has a greater effect on velocity profile also SWCNT in compared to the MWCNT has a greater effect on temperature profile and heat transfer.
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•CNTs-water nanofluids as a micropolar dusty fluid are investigated.•Influence of MHD and joule heating effect over stretching plate are investigated.•The numerical method is employed to solving the nonlinear equations.
Single-molecule magnets (SMMs) containing only one metal center may represent the lower size limit for molecule-based magnetic information storage materials. Their current drawback is that all SMMs ...require liquid-helium cooling to show magnetic memory effects. We now report a chemical strategy to access the dysprosium metallocene cation (Cp
)Dy(Cp*)
(Cp
, penta-iso-propylcyclopentadienyl; Cp
pentamethylcyclopentadienyl), which displays magnetic hysteresis above liquid-nitrogen temperatures. An effective energy barrier to reversal of the magnetization of
= 1541 wave number is also measured. The magnetic blocking temperature of
= 80 kelvin for this cation overcomes an essential barrier toward the development of nanomagnet devices that function at practical temperatures.
The surface morphology of Li metal anode significantly dictates the stability and safety of Li metal batteries. The key parameters for morphological control and causes for dendritic growth of Li ...anode are still not clear. Although the plating kinetics is generally believed to be associated with Li growth habits, the detailed models are still not well defined. In this work, the temperature effect on the stability and efficiency of Li anode is systematically investigated in a variety of electrolyte composition for Li metal batteries. A dendrite‐free growth mechanism is observed, and a high Coulombic efficiency up to ≈99.4% in Li||Cu cells is achieved by tuning the deposition behaviors at elevated temperatures. The results provide insights into the Li dendrite growth mechanism and general principle for developing stable Li anode.
The temperature effect on lithium metal anodes is demonstrated in a variety of aprotic electrolytes. High Coulombic efficiency and dendrite‐free growth modes can be achieved in an ether‐based electrolyte at elevated temperature. The electrochemical kinetics of lithium plating/stripping processes are significantly improved at high temperature.
Recent research using 3D printing to create active structures has added an exciting new dimension to 3D printing technology. After being printed, these active, often composite, materials can change ...their shape over time; this has been termed as 4D printing. In this paper, we demonstrate the design and manufacture of active composites that can take multiple shapes, depending on the environmental temperature. This is achieved by 3D printing layered composite structures with multiple families of shape memory polymer (SMP) fibers - digital SMPs - with different glass transition temperatures (Tg) to control the transformation of the structure. After a simple single-step thermomechanical programming process, the fiber families can be sequentially activated to bend when the temperature is increased. By tuning the volume fraction of the fibers, bending deformation can be controlled. We develop a theoretical model to predict the deformation behavior for better understanding the phenomena and aiding the design. We also design and print several flat 2D structures that can be programmed to fold and open themselves when subjected to heat. With the advantages of an easy fabrication process and the controllable multi-shape memory effect, the printed SMP composites have a great potential in 4D printing applications.
The technology used to process titanomagnetite is currently limited to the rotary kiln-electric furnace. Other techniques are being developed, including the separation of iron in the form of iron ...nugget from the reduction of titanomagnetite with coal without any flux addition. The effect of different temperature patterns on the formation of iron nuggets from titanomagnetite was studied. The initial temperature was varied from 700 to 1380 °C, while the final temperature was kept constant at 1380 °C. The experiment results showed that the initial temperature affected the formation of iron nuggets. Initial temperatures of 700-1100 °C produced many iron nuggets up to 3 mm in size and an initial temperature of 1200 °C produced one nugget with a size of about 4 mm. Initial temperatures of 1300 and 1380 °C did not produce any iron nuggets due to the formation of metallic iron crust on the surface of the reduced briquettes. The optimum initial temperature was 1000 °C to achieve high iron recovery in the nuggets.
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