Temperature Shock Research Articles

Pt/Mo chalcogenide composite deriving from Pt-Mo6S8 by high temperature shock for enhanced HER performance

Highly efficient catalysts for electrolysis of water are crucial to the development of hydrogen energy which is helpful to carbon neutralization. Recently, high temperature shock (HTS), with advantage of rapid speed, universality and scalable production, has been a promising method in synthesis of nanomaterials. In this paper, HST was used to treat low Pt loading Mo6S8 for enhanced water splitting performance. Impressively, the optimized MoS2/MoO2/Mo6S8 nano-composite with low Pt mass loading (∼4%) displays well hydrogen evolution reaction (HER) electrochemical performance. The overpotential is 124 mV to reach 10 mA/cm2 and the corresponding Tafel slope is 88 mV/dec in acidic electrolyte. Its mass activity is 6.2 mA/µgPt at -124 mV vs. RHE, which is almost 2 times relative to 20% Pt/C. Moreover, it presents distinguished stability even after 2000 cycles. This work will broaden the way of catalysts preparation and the application of hydrogen evolution.

Simulation of crack propagation in solder layer of IGBT device under temperature shock by viscoplastic phase field method

Insulated Gate Bipolar Transistor (IGBT) is a key device in power system. During its service, due to the mismatch of thermal expansion coefficients, cracking of the solder layer may result in reliability concerns. However, the thickness of the solder layer is generally only tens of microns, so it is challenging to study the dynamic crack propagation in the solder layer. In this study, the viscoplastic phase field method is combined with the Anand viscoplastic model commonly used in solder alloys to simulate the dynamic fracture of the IGBT solder layer during temperature shock test (TST). The simulation results are compared with the experimental results and the results are very close. In this paper, the effect of solder voids and solder inclination on crack propagation is studied by using phase field method. It is found that the presence of voids promotes crack propagation, and the crack propagation rate is faster on the thin side when the solder is tilted.

TOO HOT FOR SUSTAINABLE DEVELOPMENT: CLIMATE CHANGE AND ENERGY EFFICIENCY

Previous studies have focused on the benefits of adaptation in mitigating the negative effect of climate change on economic production, neglecting that adaptive energy input cannot be directly translated into output, which may be a barrier to sustainable development. Based on panel data from 280 cities in China from 2003 to 2016, we first calculate the energy efficiency as a proxy for sustainable development by using the nonradial directional distance function (NDDF) method. Second, we estimate energy efficiency as a function of temperature shocks, and we use these estimates to predict future potential impacts from climate change. We find three primary results: First, higher temperatures substantially reduce energy efficiency. Second, the heat effect on energy efficiency is homogenous across regions with different climates, suggesting that while adaptations in hot regions can mitigate the harmful effects of heat on output, this mitigation is completely offset by the concomitant increase in energy costs. Third, the energy efficiency would decrease by 2.82% in the medium term (2041–2060) and by 12.02% in the long term (2061–2080), under the assumption that carbon dioxide emissions continue to increase throughout the 21st century. These findings suggest that moderate adaptations to climate change are crucial for sustainable development.

An analysis of temperature anomalies in Chile using fractional integration

This paper deals with the study of stationarity and mean reversion in the temperature anomalies series in the southwestern American cone. In particular, monthly temperatures in 12 Chilean meteorological stations were studied (from the 1960’s to nowadays), examining if temperature shocks are expected to remain in the long term or if they are reversible. The results clearly show a significant relationship between the latitude, climate, and the order of integration of the temperatures. The orders of integration tend to be smaller in colder southern parts, therefore impacts of climate change are expected to be more reversible. However, in northern desert areas the orders of integration are larger than 0.5, thus impacts are expected to be maintained for a longer time.

Into the tropics: Temperature, mortality, and access to health care in Colombia

This paper analyzes the relationship between temperature, mortality, and adaptation opportunities in a tropical country. Such countries host almost 40% of the world’s population and face inherently different environmental, demographic, and socio-economic conditions than their counterparts in temperate areas. Using detailed data from all Colombian municipalities, I show that anomalously hot or cold days increase mortality even at narrow temperature ranges, which are characteristic of the tropics. An additional day with a mean temperature above 27 °C (80.6 ∘F) increases mortality rates by approximately 0.24 deaths per 100,000, equivalent to 0.7% of monthly death rates. Unlike temperate locations, I find that deaths attributed to infectious diseases and respiratory illnesses drive this relationship in the hot part of the distribution, mainly affecting children aged 0–9. These findings uncover new factors and populations at risk and imply that the average person who dies after a hot temperature shock loses approximately 30 years of life. I also provide evidence that access to health care and quality of services could mediate between temperature and mortality.

Direct observation of the ultrafast formation of cation-disordered rocksalt oxides as regenerable cathodes for lithium-ion batteries

Lithium-rich cation-disordered rocksalt (DRX) oxides offer promising prospects of satisfying boosting demand for high performance lithium-ion batteries. We introduce a time- and energy-saving high temperature shock synthesis for fast fabrication of these materials, which occurs through formation of binary oxides undergoing transformation to DRX oxides. Variations of morphology, elemental distribution, and microstructure of DRX oxides during the synthesis were followed using the in-situ transmission electron microscopy. The compositional space of DRX oxides varied from binary to senary, demonstrating that the high temperature shock strategy is a general process for their synthesis. Moreover, we demonstrated how the cycling life of DRX oxide cathodes applied in lithium-ion batteries could be extended through recrystallization of their collapsed lattice structure, and this regeneration process was accomplished using the same high temperature shock strategy. The specific capacity of the regenerated cathodes could be recovered to 91.4% of the initial value. Thus, our study offers a general strategy for not only synthesizing DRX oxides but also regenerating the respectively spent cathodes to extend the cycling life of lithium-ion batteries.

Preparation and thermal shock resistance investigation of ZTA-La2O3 composite ceramics for porous medium combustion materials

Zirconia-alumina composite ceramics are the preferred materials for high temperature and thermal shock applications because of their excellent mechanical properties. In this paper, La2O3 doped zirconia-alumina composite ceramics were prepared by using fused zirconia corundum and ZrO2 as starting materials. The effects of La2O3 on the phase composition, microstructure and properties of the composite ceramics were investigated by XRD and SEM. The results show that La2O3 can reduce the sintering temperature and improve the bending strength of the samples. The bending strength and fracture toughness of the composite ceramics with 1.5 wt% La2O3 sintered at 1480 °C are 299.17 MPa and 5.61 MPa m1/2, respectively. The strength loss rate of the sample after 30 thermal shocks (room temperature ∼ 1000 °C) is 2.67%, SEM shows that the grain sizes of alumina and zirconia in the sintered sample were about 5 μm and 2 μm, respectively. After 30 thermal shocks, the phase composition and microstructure of the sample have no significant change, indicating good thermal shock resistance of the composite ceramics. The excellent thermal shock resistance ensures porous medium combustion materials has a long service life.

Temperature, storage, and natural gas futures prices

AbstractPrevious literature suggests that daily changes in US natural gas (NG) futures prices and their variance can be explained by changes in oil futures prices and volatilities, storage announcements, and temperature shocks. These studies measure temperature shocks using the National Oceanic and Atmospheric Administration definitions of heating degree day (HDD) and cooling degree day (CDD). We show how hourly temperatures can be used to better measure how long as well as how much temperatures depart above and/or below the “comfort level” within a day, the effects of temperature variability within a day, and the effects of thermal inertia. Hourly temperatures also allow us to construct measures of extreme temperatures that better match the timing of release of other market information. Another innovation is that we use more economically relevant weights to convert regional temperature shocks to national averages, and measure expected values of variables via econometric models instead of historical averages. Our results show that the proposed measures of HDD and CDD and temperature changes are important for explaining weekly changes in NG in storage and daily changes in NG futures prices and their variance.

Cloning, recombinant expression, purification, and functional characterization of AGAAN antibacterial peptide.

A recombinant version of the AGAAN antimicrobial peptide (rAGAAN) was cloned, expressed, and purified in this study. Its antibacterial potency and stability in harsh environments were thoroughly investigated. A 15kDa soluble rAGAAN was effectively expressed in E. coli. The purified rAGAAN exhibited a broad antibacterial spectrum and was efficacious against seven Gram-positive and Gram-negative bacteria. The minimal inhibitory concentration (MIC) of rAGAAN against the growth of M. luteus (TISTR 745) was as low as 60µg/ml. Membrane permeation assay reveals that the integrity of the bacterial envelope is compromised. In addition, rAGAAN was resistant to temperature shock and maintained a high degree of stability throughout a reasonably extensive pH range. The bactericidal activity of rAGAAN ranged from 36.26 to 79.22% in the presence of pepsin and Bacillus proteases. Lower bile salt concentrations had no significant effect on the function of the peptide, whereas higher concentrations induced E. coli resistance. Additionally, rAGAAN exhibited minimal hemolytic activity against red blood cells. This study indicated that rAGAAN may be produced on a large scale in E. coli and that it had an excellent antibacterial activity and sufficient stability. This first work to express biologically active rAGAAN in E. coli yielded 8.01mg/ml at 16°C/150rpm for 18h in Luria Bertani (LB) medium supplemented with 1% glucose and induced with 0.5mM IPTG. It also assesses the interfering factors that influence the activity of the peptide, demonstrating its potential for research and therapy of multidrug-resistant bacterial infections.

Polyploidy and its relevance in crop improvement

Many areas of research in crop production have been geared towards crop improvement and increased yield. Crop improvement include but not restricted to; plant introduction and acclimatization, domestication, ploidy manipulation (polyploidization), recombinant DNA technology, crossing for superior selection (cultivar development), molecular genetics, etc. Polyploidy is a condition where the genome of an organism has more than the usual number of complete sets of chromosomes and the product of this phenomenon is called a Polyploid. Polyploidy occurs naturally, and can be induced chemically using antimitotic agents or physically using protoplast fusion and temperature shock. It is mostly artificially induced through a process called polyploidization. Polyploids are more advantageous in important plant attributes than the regular diploid. Relative success has been reported in the application of polyploidization for crop improvement which resulted chiefly in increased amount of beneficial secondary metabolites (phytochemicals), larger stomata and leaves,improved adaptation to stress and unfavourable conditions, to mention but a few. Therefore, it is imperative to state that polyploidy is an area of research that has been and will continually be deployed in crop improvement .

Biogas production of food waste with in-situ sulfide control under high organic loading in two-stage anaerobic digestion process: Strategy and response of microbial community

A two-stage anaerobic digestion process utilizing food waste was investigated in this study, without any additive and co-digestion. Solid content, temperature and pH value were key controlling factors for hydrolysis, which results the optimized food waste hydrolysate with COD/VSfood waste of 2.67. Efficient biogas production was maintained in long-term operation (>150 d) without any additive, and methane production yields up to 699.7 mL·gVS-1·d-1 was achieved under organic loading rate (OLR) of 31.0 gVS·d-1. Methane production can be recovered (70.4 %) after temperature shock within 30 days. This study confirmed the possibility to establish two-stage food waste anaerobic digestion system under high organic load. pH, OLR, and temperature are key factors to maintain stable biogas production, while pH control was performed as a in situ sulfide control technology (75.8 % sulfide reduction). This study provides practical strategies for food waste utilization and decreasing carbon footprint.

Biofilter-constructed wetland-trophic pond system: A new strategy for effective sewage treatment and agricultural irrigation in rural area

Artificial ecosystems with high biological complexity are generally considered to be efficient in metabolizing substances and resistant to temperature shock. In this study, a novel near-natural system (BCT system), which consisted of simple biofilter, constructed wetland and trophic biology pond, was conducted to treat rural sewage in situ for irrigation into farmland. Water quality related to carbon and nutrients and microbial community were analyzed along the system to reveal the effect of each unit. The annual average removals of BCT system for TN, NH4+-N, TP and COD could reach 46.53%, 52.18%, 41.48%, and 53.21%, respectively. There was no significant decrease for removal efficiencies from high temperature period (HTP, ≥15 °C) to low temperature period (LTP, <15 °C). In LTP, the trophic pond (TRP) removed 34.85% of TN, 33.93% of NH4+-N, 13.71% of TP and 18.77% of COD, while the removal efficiencies of constructed wetland fluctuated greatly. The TRP facilitated the BCT system to maintain the removal capability during low temperature period. The relative abundance of denitrification functional genes in TRP increased nearly tenfold from HTP to LTP. The effluent quality from the system can meet the agricultural irrigation standards, demonstrating the effect of BCT system on sewage treatment and agricultural irrigation in rural area.

Accelerated performance recovery of anaerobic granular sludge after temperature shock: Rapid construction of protective barriers (EPS) to optimize microbial community composition base on quorum sensing

Poor temperature shock resistance of anaerobic granular sludge (AnGS) is one of its main disadvantages. In this study, enhancing the temperature shock resistance of AnGS by regulating quorum sensing (QS) based on the exogenous addition of N-acyl homoserine lactones (AHLs) was investigated, and the regulatory mechanism of AHLs-mediated QS based on extracellular polymeric substances (EPS) action in AnGS was revealed. The results indicated that adding 10 μM AHLs significantly enhanced the COD removal (increased by 9.3 ± 1.2%) and specific methanogenic activity (increased by 15.2 ± 3.6%) of AnGS after temperature shock, and the recovery time was reduced by 4 days. The sludge breakage and particle size reduction induced by temperature shock were attenuated by AHLs-mediated QS. Meanwhile, exogenous AHLs increased EPS concentration and the number of hydrophobic functional groups in AnGS. The addition of 10 μM AHLs reduced the ratio of Firmicutes to Bacteroidota (decreased by 0.17 ± 0.01), leading to higher microbial community stability. The enrichment of major functional bacteria (Bacteroidota, Desulfobacterota and Firmicutes) and hydrogenotrophic methanogens (Methanothermobacter and Methanobacterium) was promoted by 10 μM AHLs. The increased EPS induced by AHLs provided the protection for microbial community optimization, leading to the rapid recovery of the temperature-shocked AnGS performance. This study provided a new comprehensive insight into the regulatory mechanisms of AHLs-mediated QS in AnGS.

Investigation of the Stress-Strain State of a Rectangular Plate after a Temperature Shock

In this paper, the temperature shock phenomenon is considered. This phenomenon occurs during the operation of engineering structures on Earth and in outer space. A rectangular plate has been selected as a structural element exposed to temperature shock. It has a rigidly sealed edge and three free edges. A one-dimensional third initial boundary value problem of thermal conductivity was posed and solved to study the stress–strain state of the plate. Fourier’s law was used to solve this problem, taking into account the inertial term, since the temperature shock is a fairly fast-dynamic phenomenon. It was believed that all the thermophysical properties of the plate are constant and do not depend on its temperature. As a result, the temperature field of the plate was obtained after the temperature shock. This temperature field generates temperature stresses inside the plate, which lead to temperature deformations. To determine these deformations, the initial boundary value problem of thermoelasticity was posed and solved in this work. The Sophie Germain equation was used while solving this problem. To describe the plate, the theory of flexible plates was used, taking into account the stresses in the middle surface of the plate. Next, the accuracy of analytical solutions for the points displacement of a homogeneous plate subjected to a temperature shock was investigated. The temperature field was constructed using a numerical simulation. Functions of the displacement vector components were obtained using approximate analytical solutions. The accuracy of approximate analytical solutions for the components of the plate points deformation vector was estimated. The obtained results allow us to describe the stress–strain state of the plate after the temperature shock. The results of this work can be used in the design of engineering structures for both terrestrial and space purposes in terms of stability calculations and the implementation of deformation constraints.

Estimation of Panel Data Models with Mixed Sampling Frequencies*

AbstractStandard panel models usually assume that data are available at the same frequency. Occasionally, researchers might work with variables sampled at different frequencies. A common practice is to aggregate all variables to the same frequency by an equal weighting scheme. We show that such a simple aggregation scheme results in biases for common estimators. We propose a data‐driven method to determine weights for aggregation. We further demonstrate that, in contrast with single‐frequency panel models, the Mundlak device and the Chamberlain's approach lead to different estimators for panels with mixed sampling frequencies. The proposed estimators have satisfying finite sample performances in various simulation designs. As an empirical illustration, we apply the new method to the estimation of the effects of temperature fluctuations on economic growth. The empirical evidence shows that the temperature shocks mainly work through the level effect instead of the growth effect for poor countries.

The Symmetric Formulation of the Temperature Shock Problem for a Small Spacecraft with Two Elastic Elements

The paper considers the problem of a small-spacecraft elastic elements’ temperature shock that occurs when the spacecraft immerses into the Earth’s shadow or comes out of it. A small spacecraft with two elastic elements is simulated. In the first approximation, such a problem is considered to be a symmetric problem. Estimations of disturbing factors from the temperature shock in a symmetric formulation are obtained. The differences from the results for a small spacecraft with a single elastic element are analyzed. The results of the work can be used for promising small technological spacecraft development, as well as for solving problems of space debris removal and remote sensing of the Earth.

Towards the Control of the Reproduction of the Yellow Clam Amarilladesma mactroides (Reeve, 1854) in Captivity: Effects of Different Stimuli on the Spawning of Laboratory-Conditioned and Unconditioned Breeders

The effects of temperature manipulation, addition of sperm solution, and exposure to alkalized pH and/or hydrogen peroxide (H2O2) as possible spawning inducers in laboratory-conditioned and unconditioned adults of the yellow clam (Amarilladesma mactroides) were evaluated. In three trials, clams were laboratory-conditioned for 14 days and exposed to thermal shocks (from 20 °C to 23–29 °C), while clams from three additional trials were not conditioned but acclimatized for 45 min before spawning induction. Although conditioning advanced gonad maturity and increased the condition factor, none of the thermal treatments triggered spawning in these first trials. Histological analysis indicated that the gonads of conditioned clams were not mature. Alternatively, unfertilized and fertilized eggs, and larvae were observed after unconditioned clams were induced to spawn. The gonads of unconditioned clams were in an advanced stage of maturity. Exposure to temperature shocks, alone or in combination with the addition of sperm solution and with H2O2, resulted in spawning. Clams exposed to H2O2 kept their valves closed and had a high mortality rate. Temperature manipulation is the most promising stimulus to induce spawning in A. mactroides. As the success of conditioning depends on the stage of gonadal development at the time of capture in the wild, a period longer than 14 days may be necessary.

Modeling the deformation of an elastic element of a small spacecraft in its plane during temperature shock

A basic mathematical model of the deformation of a large elastic element of a small spacecraft in its plane is constructed. Deformations are caused by a temperature shock after a small spacecraft leaves the Earth’s shadow on the solar portion of the orbit. The model is used to conduct a computational experiment with the aim of assessing perturbations acting on a small spacecraft due to temperature shock. The temperature distribution during thermal shock is described by a one-dimensional model of thermal conductivity. The classical theory of thin plates is used to determine the deformations. The results of the estimation of disturbing factors are obtained as a result of a computational experiment for a model small spacecraft. These results indicate the need to compensate for the impact of temperature shock for small technological spacecraft. The data obtained can be used in the design of small space-craft for technological purposes.

The importance of a three-dimensional formulation of the thermal conductivity problem in assessing the effect of a temperature shock on the rotational motion of a small spacecraft

The paper analyzes the conditions under which a two-dimensional formulation of the thermal conductivity problem for a correct assessment of the large elastic elements temperature shock effect on the rotational motion of a small spacecraft is insufficient. Numerical simulation was carried out for a scheme of a small “Aist-2D” spacecraft. The results of this work can be used in modeling the rotational motion of a small spacecraft taking into account the temperature shock of large elastic elements.

Role of temperature fluctuations and shocks during refrigeration on pork and salmon quality

AbstractRefrigeration is considered a prime technology for preserving meat products. Temperature alterations are commonly ignored by industry during refrigeration, which have impacts on product quality. Thus, we conducted research on pork loin and salmon fillets that were preserved for 0, 5, 9, 12, and 15 d, where different temperature fluctuations and shocks were established on 4 °C. Data revealed that several meat parameters such as total volatile basic nitrogen, total viable count, and lipid oxidation were significantly changed in the ±2 °C fluctuations group compared with the constant temperature group. Additionally, both the temperature fluctuations and shocks groups had accelerated myofibril protein degradation, while desmin expression and species richness/diversity of bacteria were significantly reduced in the ±2 °C fluctuations group compared with the constant temperature group. Briefly, temperature fluctuations and shocks accelerated the destruction of muscle structural integrity. Furthermore, both conditions accelerated meat spoilage by progressively expanding the water-loss channels, which can reduce meat edibility. This study provides a new theoretical basis for the proper use of refrigerated temperatures for storing meat products.