Short-term High Temperature Research Articles

The effects of fusion reactor thermal transients on the microstructure of Eurofer-97 steel

Plasma-wall interactions in a commercial-scale fusion power station may exert high transient thermal loads on plasma-facing surfaces, repeatedly subjecting underlying structural materials to high temperatures for short durations. Specimens of the reduced activation ferritic-martensitic steel Eurofer-97 were continuously aged at constant temperature in the range of 550°C to 950°C for up to 168 hours in a furnace to investigate the microstructural effects of short-term high temperature exposure. A CO2 laser was also used to repeatedly heat another specimen from 400°C to 850°C a total of 1,480 times over a period of 41 hours to explore transient heating effects. Microstructural changes were studied via scanning electron and focused ion beam microscopy and include (i) the coarsening of Cr-rich secondary phase precipitates when continuously heated above 750°C, (ii) an increase in average grain size above 800°C and (iii) the evolution of a new lath martensite microstructure above 850°C. Conversely, transient heating via a laser was found to result in the decomposition of the as-received lath martensite structure into ferrite and Cr-rich carbide precipitates, accompanied by a significant increase in average grain size from 0.1-2 µm to 5-40 µm. Experimental analysis was supported by thermodynamic simulation of the equilibrium phase behaviour of Eurofer-97 in MatCalc and thermal finite element modelling of plasma-wall interaction heating on the water-cooled lithium-lead tritium breeding blanket concept in Comsol Multiphysics. Simulated thermal transients were found to significantly alter the microstructure of Eurofer-97 and the implications of this are discussed.

A phenomenological model for predicting long-term high temperature creep life of materials from short-term high temperature creep test data

A phenomenological analysis for predicting the long-term creep life of high temperature materials at different temperatures using model parameters derived from short-term creep tests is presented. The model invokes Maxwell-Boltzmann temperature dependence, as rigorously developed in a recent analysis pertaining to the power law domain and a modified form of the Monkman-Grant hypothesis for isothermal conditions. In addition, the model provides, by pattern recognition, suitable weighting factors for the role of strain rate and temperature. The result is a material-dependent analysis which uses only short-term creep test data but is able to predict accurately both the short- and long-term creep behaviour of several complex creep-resistant alloys. This analysis is validated using reliable and accurate creep data taken from NIMS (National Institute of Materials Science, Japan) database pertaining to 10 industrial, high temperature alloys. The consistency or otherwise of the predictions is examined and the importance of the weighting factors in ensuring accurate predictions is emphasized.

Effect of short-term high temperature on the accumulation of glucosinolates in Brassica rapa

Glucosinolates, an important class of secondary metabolites in cruciferous vegetables, play a crucial role in protecting plants from stress-related damage. The mechanism of glucosinolate synthesis under short-term high temperature stress has not been sufficiently studied. In this work, we investigated the changes in transcription factors, synthetic genes, and related metabolites involved in glucosinolate synthesis by pakchoi seedlings under short-term high temperature stress (40 °C for 8 h). Short-term high temperature stress inhibited the primary sulfur assimilation and the contents of methionine, cysteine and glutathione. The contents of aliphatic and indolic glucosinolates were increased by short-term high temperature stress, whereas the content of 4-methoxy-glucobrassicin increased significantly. During the stress period, the transcript level of glucosinolate related MYB transcription factors had been basically significantly up-regulated, whereas the transcript level of aliphatic and indolic glucosinolate synthetic genes were predominantly up-regulated and down-regulated respectively. In the early recovery period, primary sulfur assimilation up-regulated rapidly, and decreased during the late recovery process. The glucosinolate content and synthesis gene expression act similar to the primary sulfur assimilation, a short up-regulated in early recovery, then all go down at 40 and 48 h after short-term high temperature treatment.

Root isoprene formation alters lateral root development

Isoprene is a C5 volatile organic compound, which can protect aboveground plant tissue from abiotic stress such as short-term high temperatures and accumulation of reactive oxygen species (ROS). Here, we uncover new roles for isoprene in the plant belowground tissues. By analysing Populus x canescens isoprene synthase (PcISPS) promoter reporter plants, we discovered PcISPS promoter activity in certain regions of the roots including the vascular tissue, the differentiation zone and the root cap. Treatment of roots with auxin or salt increased PcISPS promoter activity at these sites, especially in the developing lateral roots (LR). Transgenic, isoprene non-emitting poplar roots revealed an accumulation of O2 - in the same root regions where PcISPS promoter activity was localized. Absence of isoprene emission, moreover, increased the formation of LRs. Inhibition of NAD(P)H oxidase activity suppressed LR development, suggesting the involvement of ROS in this process. The analysis of the fine root proteome revealed a constitutive shift in the amount of several redox balance, signalling and development related proteins, such as superoxide dismutase, various peroxidases and linoleate 9S-lipoxygenase, in isoprene non-emitting poplar roots. Together our results indicate for isoprene a ROS-related function, eventually co-regulating the plant-internal signalling network and development processes in root tissue.

Eco-Physiological Screening of Different Tomato Genotypes in Response to High Temperatures: A Combined Field-to-Laboratory Approach.

High temperatures represent a limitation for growth and development of many crop species. Several studies have demonstrated that the yield reduction of tomato under high temperatures and drought is mainly due to a photosynthetic decline. In this paper, a set of 15 tomato genotypes were screened for tolerance to elevated temperatures by cultivating plants under plastic walk-in tunnels. To assess the potential tolerance of tomato genotypes to high temperatures, measurements of chlorophyll fluorescence, pigments content and leaf functional traits have been carried out together with the evaluation of the final yields. Based on the greenhouse trials, a group of eight putative heat-sensitive and heat-tolerant tomato genotypes was selected for laboratory experiments aimed at investigating the effects of short-term high temperatures treatments in controlled conditions. The chlorophyll fluorescence induction kinetics were recorded on detached leaves treated for 60 min at 35 °C or at 45 °C. The last treatment significantly affected the photosystem II (PSII) photochemical efficiency (namely maximum PSII quantum efficiency, Fv/Fm, and quantum yield of PSII electron transport, ΦPSII) and the non-photochemical quenching (NPQ) in the majority of genotypes. The short-term heat shock treatments also led to significant differences in the shape of the slow Kautsky kinetics and its significant time points (chlorophyll fluorescence levels minimum O, peak P, semi-steady state S, maximum M, terminal steady state T) compared to the control, demonstrating heat shock-induced changes in PSII functionality. Genotypes potentially tolerant to high temperatures have been identified. Our findings support the idea that chlorophyll fluorescence parameters (i.e., ΦPSII or NPQ) and some leaf functional traits may be used as a tool to detect high temperatures-tolerant tomato cultivars.

Effect of short-term high-temperatures on the growth, development and reproduction in the fruit fly, Bactrocera tau (Diptera: Tephritidae)

Bactrocera tau (Walker) (Diptera: Tephritidae) is an economically important invasive pest, that is capable of seriously reducing the quality and yield of vegetables and fruits, it was first recorded from Fujian province in 1849 and later introduced to Yunnan province in 1912 as a result in trade fruits and vegetables of China. In recent years, with the onset of global climate change and the accompanying increase in the greenhouse effect, elevated climatic temperatures have become one of the main environmental factors affecting growth and reproduction in insects, and the optimal developmental temperature of B. tau was found to be from 25 °C to 31 °C, the growth, development and reproduction of B. tau are normal under the optimal temperature conditions. In order to determine the repercussions that elevated temperature have on B. tau, we assessed the effects that short-term (12 h) high-temperature exposures (34 °C, 36 °C, 38 °C, 40 °C, 42 °C, 44 °C, 46 °C, and 48 °C) had on the growth, development and reproduction of B. tau at different developmental stages of the fly. The results showed that the survival rate of B. tau gradually decreased in all stages following exposure to short-term high-temperatures. The pupal stage was the least sensitive to increased temperatures. The pupae withstood the highest lethal temperature, having an LT50 of 42.060 °C, followed by female adults (40.447 °C), male adults (40.013 °C), and larvae (36.740 °C). The egg stage, which was the most susceptible to heat increases, had the lowest LT50 (38.310 °C). No significant effects were observed in the developmental stages of B. tau at temperatures from 24 °C to 38 °C. The development duration was significantly prolonged at 40 °C (P < 0.05) in the eggs (2.830d), larvae (7.330d), and pupae (8.170d) (P < 0.05). B. tau was unable to survive at temperatures above 42 °C. The pre-oviposition of female adults was extended, the average egg number per female showed a downward trend, the longevity of adults gradually shortened, and the ratio of female to male offspring increased as temperature increments were increased. In summary, short-term high-temperatures over 42 °C were not suitable for successful development of B. tau, while short-term high-temperatures over 40 °C were not suitable for successful reproduction in B. tau.

Assessment of High Temperature Effects on Grain Yield and Composition in Bread Wheat Commercial Varieties

Wheat is one of the most important cereals for food and feed, and it is, therefore, necessary to determine the effects of short-term high temperature events (heatwaves) during grain filling. These heatwave events are increasingly common, especially in Portugal. In this work, seven commercial varieties recommended for production in Portugal were submitted to one-week high temperature (HT) treatment ten days after anthesis to evaluate heat effects on grain yield and quality. Grain yield parameters, such as grain number and weight, were evaluated as well as grain composition through attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Variation in HT response between varieties was detected. Grain number and weight tended to decrease in most varieties analyzed. However, two varieties proved to be more resilient since grain number and weight remain unaltered in the Bancal variety, which is the one with better yield results, and even increased in the Pata Negra variety. Regarding grain composition, the comparison between ATR-FTIR spectra of milled grains from control and HT plants revealed alterations in peaks assigned to polysaccharides and proteins. Additionally, a model was built based on nitrogen elemental analysis to predict protein content in flour samples through spectral data that corroborated the differences identified by spectra profile comparison. Moreover, both analyses showed that the intervarietal diversity observed in control conditions was significantly reduced in HT treated plants. The results obtained highlight the intervarietal diversity of wheat response to HT, regarding grain yield parameters, grain composition, and particularly, protein content.

Characterization of Kyagar Glacier and Lake Outburst Floods in 2018 Based on Time-Series Sentinel-1A Data

Early recognition of glacial lake outburst floods (GLOFs) is required for timely and cost-effective remedial efforts to be implemented. Although the formation of ice-dammed lakes is known to begin as a pond or river that was blocked by ice from the glacier terminus, the relationship between glacier dynamics and lake development is not well understood. Using a time-series of Sentinel-1A synthetic aperture radar (SAR) data acquired just before and after the lake outburst event in 2018, information is presented on the dynamic characteristics of Kyagar Glacier and its ice-dammed lake. Glacier velocity data derived from interferometry show that the glacier tongue experienced an accelerated advance (maximum velocity of 20 cm/day) just one month before the lake outburst, and a decreased velocity (maximum of 13 cm/day) afterward. Interferometric and backscattering properties of this region provide valuable insight into the diverse glaciated environment. Furthermore, daily temperature and total precipitation data derived from the ECMWF re-analysis (ERA)Interim highlight the importance of the sustained high-temperature driving force, supporting empirical observations from previous studies. The spatial and temporal resolution offered by the Sentinel-1A data allows variations in the glacier surface motion and lake evolution to be detected, meaning that the interaction mechanism between the glacial lake and the associated glacier can be explored. Although the glacier surge provided the boundary conditions favorable for lake formation, the short-term high temperatures and precipitation caused the melting of ice dams and also a rapid increase in the amount of water stored, which accelerated the potential for a lake outburst.

The Influence of Deformation and Short-Term Hightemperature Annealing on the Microstructure and Mechanical Properties of Austenitic Steel 17Cr-14Ni-3Mo (316 Type)

The deformation and thermal action on the microstructure and mechanical properties of a stable austenitic Cr-Ni stainless steel is investigated. It is shown that under deformation conditions packets of microtwins and bands of localized deformation with the inner fragmented structure are formed, where the fragments are of the submicro- and nanocrystaalline scales with low- and high-angle misorientation boundaries. These features of microstructure ensure high yield-point values ≈1100 MPa at a relative elongation of ≈6–7%. Short-term (to 150 s) high-temperature (850°С) annealing of the deformed structure gives rise to a local development of the processes of polygonization and recrystallization in the regions of strain localization bands. As a result of such annealing, packets of microtwins, strain localization bands, polygonized subgrains and recrystallized grains of primarily submicron dimensions are observed in the steel structure. The resulting structural states ensure the yield strength values up to 740 MPa at the relative elongations ≈20–28%. The physical processes taking place in the steel under the experimental deformation and annealing conditions are discussed.

Resistors for High Temperature Applications

Abstract The use and growth of high temperature electronics in a variety of applications (such as oil and gas exploration and production, automotive under the hood, aerospace and satellite/space to name a few), has necessitated a closer look at the technology used in passive components (such as resistors). A variety of resistor technologies may be suitable for high temperature applications. In the paper information, on thin film technologies (both nichrome and tantalum nitride thin film information is presented), thick film, and wire-wound construction is presented, with discussions regarding their respective characteristics that make them more or less suitable for high temperature and other excessive environments. This paper presents information on resistor construction details, material information and manufacturing processing, along with test data and performance summaries under short and long term high temperature conditions. Additionally, other pertinent test data through typical environmental tests is presented Although resistors and other passive components are often taken for granted, high temperature applications can tax the performance of many resistor types. The proper selection of resistive components will insure that the stability, temperature coefficient (and temperature coefficient tracking for resistor networks), and reliability is maintained to insure reliable circuit performance.

MAIN PROPERTIES OF ABRASIVE DENTISTRY MATERIALS UTILIZED IN POLISHING OF REMOVABLE DENTURE BASES

The requirements to the quality of dental prostheses are currently very high. All dental prostheses need thorough final finishing through filing and polishing in order to obtain smooth, polished, shiny and esthetic surface. In addition to comfort and aesthetics this guarantees high hygienic quality of dental prostheses and extends their operational characteristics. Smooth and even surface of plastic or thermoplastic prostheses can more efficiently resist aging and decay caused by the change of temperature and bacterial flora activity which typically occur in the mouth cavity.&#x0D; Modern orthopedic dentistry utilizes various abrasive materials for filing and polishing of removable dentures made from different materials. Filing is the method of removing roughness and unevenness from the surface of dentures. Polishing is the final process of finishing aimed at obtaining smooth, shiny surface of dentures. It has been proved that rough and badly polished surface of dentures can cause significant patient’s discomfort and complicate hygiene of the mouth cavity. Together with the aggressive environment of the mouth cavity, such surfaces can lead to dental plague and tartar deposit, which, correspondingly, leads to bad smell, stomatitis and other dental and general illnesses. It has been proved that high quality finishing of the surface of removable dentures contributes to the improvement of their sustainability, durability and aesthetic characteristics. Well-polished surface of removable dentures more efficiently resists the processes of destruction, such as aging and decay, caused by the change of temperature and bacterial flora activity.&#x0D; The analysis of bibliography has shown that the process of polishing and the quality of the surface under work depend on a number of factors. The most significant role belongs to the size of abrasive particles, the pressure of abrasive on material and its thermal conductivity, the speed at which abrasive particles move along the surface. Grains of the size 0,15-0,75 mm are used most often. It has been specified that coarse polishing can utilize grains of bigger size reaching 1,5-2 mm. It has been proved that the pressure of abrasive should be light in order to prevent the damage of dentures or instruments. Moreover, excess pressure can cause overheating of an instrument or the surface of dentures being polished. It has also been demonstrated that even short-term high temperature exposure can result in polymer deformation which reduces sustainability and durability of removable dentures. It is known that overheating can be avoided on condition of following the basic rules of polishing.&#x0D; Orthopedic dentistry utilizes pumice, silicate or aluminum oxide, silicone dioxide as abrasive filler. The particular interest presents the study of the efficiency of zirconium silicate as an abrasive component of polishing paste for finishing of thermoplastic polymer bases and providing full gloss of the surface. Stearin, paraffin, wax, petrolatum are used as the components of surfactants, as they demonstrate low surface tension and facilitate spreading the paste on the polished surface.&#x0D; There is not a wide range of locally produced polishing pastes utilized in dentistry. They leave traces, microscratchings; do not allow obtaining even, smooth shiny surface of dentures with thermoplastic polymer basis. Finishing of removable dentures requires a lot of time and expenses from professionals.

New insights in the relation between climate and slope failures at high-elevation sites

Climate change is now unequivocal; however, the type and extent of terrestrial impacts are still widely debated. Among these, the effects on slope stability are receiving a growing attention in recent years, both as terrestrial indicators of climate change and implications for hazard assessment. High-elevation areas are particularly suitable for these studies, because of the presence of the cryosphere, which is particularly sensitive to climate. In this paper, we analyze 358 slope failures which occurred in the Italian Alps in the period 2000–2016, at an elevation above 1500 m a.s.l. We use a statistical-based method to detect climate anomalies associated with the occurrence of slope failures, with the aim to catch an eventual climate signal in the preparation and/or triggering of the considered case studies. We first analyze the probability values assumed by 25 climate variables on the occasion of a slope-failure occurrence. We then perform a dimensionality reduction procedure and come out with a set of four most significant and representative climate variables, in particular heavy precipitation and short-term high temperature. Our study highlights that slope failures occur in association with one or more climate anomalies in almost 92% of our case studies. One or more temperature anomalies are detected in association with most case studies, in combination or not with precipitation (47% and 38%, respectively). Summer events prevail, and an increasing role of positive temperature anomalies from spring to winter, and with elevation and failure size, emerges. While not providing a final evidence of the role of climate warming on slope instability increase at high elevation in recent years, the results of our study strengthen this hypothesis, calling for more extensive and in-depth studies on the subject.

Effect of different short-term high ambient temperature on chicken meat quality and ultra-structure.

ObjectiveThis study investigated the effect of different acute heat stress (HS) levels on chicken meat quality and ultra-structure.MethodsChickens were randomly divided into 7 groups to receive different HS treatments: i) 36°C for 1 h, ii) 36°C for 2 h, iii) 38°C for 1 h, iv) 38°C for 2 h, v) 40°C for 1 h, vi) 40°C for 2 h, and vii) un-stressed control group (25°C). Blood cortisol level, breasts initial temperature, color, pH, water holding capacity (WHC), protein solubility and ultra-structure were analyzed.ResultsHS temperatures had significant effects on breast meat temperature, lightness (L*), redness (a*), cooking loss and protein solubility (p<0.05). The HS at 36°C increased L*24 h value (p<0.01) and increased the cooking loss (p<0.05), but decreased a*24 h value (p<0.05). However, as the temperature increased to 38°C and 40°C, all the values of L*24 h, cooking loss and protein denaturation level decreased, and the differences disappeared compared to control group (p> 0.05). Only the ultimate pH24 h at 40°C decreased compared to the control group (p<0.01). The pH in 36°C group declined greater than other heat-stressed group in the first hour postmortem, which contributed breast muscle protein degeneration combining with high body temperature, and these variations reflected on poor meat quality parameters. The muscle fiber integrity level in group 40°C was much better than those in 36°C with the denatured position mainly focused on the interval of muscle fibers which probably contributes WHC and light reflection.ConclusionHS at higher temperature (above 38°C) before slaughter did not always lead to more pale and lower WHC breast meat. Breast meat quality parameters had a regression trend as HS temperature raised from 36°C. The interval of muscle fibers at 24 h postmortem and greater pH decline rate with high body temperature in early postmortem period could be a reasonable explanation for the variation of meat quality parameters.

Short-term high temperature treatment reduces viability and inhibits respiration and DNA repair enzymes in Araucaria angustifolia cells.

We evaluated the effect of global warming on Araucaria angustifolia (Bert.) O. Kuntze, a critically endangered native tree of Southern Brazil, by studying the effects of short-term high temperature treatment on cell viability, respiration and DNA repair of embryogenic cells. Compared with control cells grown at 25°C, cell viability was reduced by 40% after incubation at 30 and 37°C for 24 and 6 h, respectively, while 2 h at 40 and 42°C killed 95% of the cells. Cell respiration was unaffected at 30-37°C, but dramatically reduced after 2 h at 42°C. The in vitro activity of enzymes of the base excision repair (BER) pathway was determined. Apurinic/apyrimidine endonuclease, measured in extracts from cells incubated for 2 h at 42°C, was completely inactivated while lower temperatures had no effect. The activities of three enzymes of the mitochondrial BER pathway were measured after 30-min preincubation of isolated mitochondria at 25-40°C and one of them, uracil glycosylase, was completely inhibited at 40°C. We conclude that cell viability, respiration and DNA repair have different temperature sensitivities between 25 and 37°C, and that they are all very sensitive to 40 or 42°C. Thus, A. angustifolia will likely be vulnerable to the short-term high temperature events associated with global warming.

Effects of zinc fertilizer and short-term high temperature stress on wheat grain production and wheat flour proteins

Content of wheat flour proteins affects the quality of wheat flour. Zinc nutrition in wheat can change the protein content of the flour. The inconsistency and instability of wheat grain quality during grain filling while under high temperature stress (HTS) are major problems in the production of high quality wheat. At present, there is a lack of studies on zinc fertilizer and HTS effects on wheat flour protein and the content of its components. For this study, treatment combinations of four levels of zinc fertilizers and exposure to a short-term HTS, at 20 d after flowering (D20), were tested on two wheat cultivars with different gluten levels. Individuals of a strong gluten wheat, Gaoyou 2018 (GY2018), and a medium gluten wheat, Zhongmai 8 (ZM8), were grown in pots at the Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing in 2015–2017. We measured grain yield and weight and the activities of two enzymes (nitrate reductase and glutamine synthetase) from the flag leaves, collected at D10 and D20. Total protein content, protein yield, and content of four protein components (albumin, gliadin, glutenin, and globulin) were measured from flour produced from the pot-grown plants. HTS significantly increased the contents of total protein, albumin, gliadin, and glutenin in wheat grains, and reduced the grain yield, grain weight, protein yield, globulin content, and flag leaf nitrate reductase (NR) and glutamine synthetase (GS) activities. The results showed that HTS and zinc fertilizer had greater impacts on the strong gluten cultivar compared to the medium gluten cultivar. Under HTS, grain yield decreased by 13 and 8% in GY2018 and ZM8, respectively; protein yield decreased by 7 and 8% in GY2018 and ZM8, respectively. Zinc fertilizer increased: grain and protein yields; grain weight; total protein, albumin, gliadin, and glutenin contents; protein yield; and NR and GS activities. In contrast, zinc fertilizer reduced the content of globulin. The addition of 15 mg Zn kg–1 soil had the strongest effect on grain yield and quality as compared to the other three treatments (additions of 0, 30, and 45 mg Zn kg–1 soil). Zinc fertilizer also reduced the negative effects of HTS on protein yield, content, and components’ content. Therefore, wheat grown with additional zinc in the soil can improve the quality of the flour.

Novel amino-functionalized carbon material derived from metal organic framework: A characteristic adsorbent for U(VI) removal from aqueous environment

The introduction of functional groups into metal-orgnic frameworks (MOFs) is becoming a hot research topic. In this work, a novel amino-functionalized carbon material derived from MOF-5 has been synthesized successfully via a facile and fast method of short-term high temperature treatment. The resulting material of the amino-functionalized MOF-5(TEPA-C-MOF-5) exhibits high adsorption capacity (550 mg/g) for uranium and the adsorbent can reach the adsorption equilibrium at a relatively low pH (3.5). Moreover, the formation of surface carbonized layer under short-term high temperature can improve the stability in water or humidity. Compared with UiO-66 (Zr-based MOF), it is founded that only MOF-5 (Zn-based MOF) can be introduced into amino group by this method.

Evolutionary adaptation of an RNA bacteriophage to the simultaneous increase in the within-host and extracellular temperatures

Bacteriophages are the most numerous biological entities on Earth. They are on the basis of most ecosystems, regulating the diversity and abundance of bacterial populations and contributing to the nutrient and energy cycles. Bacteriophages have two well differentiated phases in their life cycle, one extracellular, in which they behave as inert particles, and other one inside their hosts, where they replicate to give rise to a progeny. In both phases they are exposed to environmental conditions that often act as selective pressures that limit both their survival in the environment and their ability to replicate, two fitness traits that frequently cannot be optimised simultaneously. In this study we have analysed the evolutionary ability of an RNA bacteriophage, the bacteriophage Qβ, when it is confronted with a temperature increase that affects both the extracellular and the intracellular media. Our results show that Qβ can optimise its survivability when exposed to short-term high temperature extracellular heat shocks, as well as its replicative ability at higher-than-optimal temperature. Mutations responsible for simultaneous adaptation were the same as those selected when adaptation to each condition proceeded separately, showing the absence of important trade-offs between survival and reproduction in this virus.

‘Hass’ avocado quality as influenced by temperature and ethylene prior to and during final ripening

Avocados (Persea americana Mill.) are often held for short periods after harvest at relatively high temperatures both in the field, in storage during preconditioning (ethylene ripening), or prior to ripening with unknown effects on subsequent quality. To better understand the quality effects of short-term high temperature exposure, avocados were harvested at five different times during the first commercial season and held at 20, 25, 30 or 35 °C for 24 h or 48 h, with and without ethylene. During the subsequent season (2) the experiment was repeated, but without the 30 and 35 °C treatments. In both seasons, following the short-term temperature treatment, fruit were either immediately ripened at 20 °C or stored for 14 d at 5 °C and then ripened to determine the influence of storage. After final ripening to eating firmness (4.4–6.7 N) the fruit were evaluated for quality parameters. Results from the first two seasons showed that even a 24 h exposure to 25 °C and above was sufficient to inhibit subsequent ripening and enhance the occurrence of postharvest disorders such as stem end rot and body rot. Application of ethylene during the short-term temperature exposure was ineffective in preventing the disorders. In the third season of the study the effect of prolonged temperature exposure on final ripening was examined. Although there had been research done in the past on this subject, prior work had not examined the effect of different ripening temperatures on flavor. Avocados were harvested at seven harvest dates, stored for either 4 d or 14 d at 5 °C and then ripened to eating firmness at temperatures ranging from 15 to 25 °C. Increasing temperatures up to 20 °C decreased ripening time, beyond which there was no further change. Avocados ripened at temperatures above 20 °C had an increased incidence of the development of pink discoloration in the mesocarp. Ripening temperature had no effect on overall likeability, or ratings of grassy or rich flavor. This correlated with a lack of clear effect of ripening temperature on aroma volatile content of the fruit. Panelists found fruit ripened at 15 °C to have a different texture that those ripened at 20 °C but this had no influence on likeability. This study strongly indicated the importance of maintaining the ripening temperature of avocados at or near 20 °C both when the fruit is ripened soon after harvest or after storage to optimize postharvest quality.

Effects of sulfur fertilization and short-term high temperature on wheat grain production and wheat flour proteins

The content of wheat flour proteins affects the quality of wheat flour. Sulfur nutrition in wheat can change the protein content of the flour. The inconsistency and instability of wheat grain quality during grain filling under high temperature stress (HTS) are a major challenge to the production of high-quality wheat. The effects of sulfur fertilization and HTS on wheat flour protein and its components are unknown. In this study, treatments varying two factors: sulfur fertilization and exposure to short-term HTS, at 20days post-anthesis, were applied to two wheat cultivars with differing gluten types. Plants of a strong-gluten wheat (Gaoyou 2018) and a medium-gluten wheat (Zhongmai 8) were grown in pots in Beijing in 2015–2017. HTS significantly increased the contents of total protein, albumin, gliadin, glutenin, Cys, and Met in wheat kernels, but reduced grain yield, grain weight, protein yield, globulin content, and total starch accumulation. The HTS-induced increase in total protein amount was closely associated with nitrate reductase (NR) and glutamine synthetase (GS) activities in flag leaves. Sulfur fertilization increased grain and protein yields; grain weight; total protein, albumin, gliadin, glutenin, and globulin contents; protein yield; total starch; Cys, Met; and NR and GS activities. HTS and sulfur fertilization had larger effects on the strong- than on the medium-gluten cultivar. Sulfur fertilization also alleviated the negative effects of HTS on grain yield, protein yield, and starch content. Thus, growing wheat with additional soil sulfur can improve the quality of the flour.

Characterization of the effect of short-term high temperature and vibration on wine by quantitative descriptive analysis and solid phase microextractiongas chromatography-mass spectrometry

The effect of short-term higher ambient temperature (HT) and continuous vibration (CV) treatment was comparatively characterized by sensory evaluation and chemical analysis. Results of quantitative descriptive analysis of modified frequency (MF) showed that HT causes both in red wine and white wine a decrease of fruity and floral characters, an unbalance of taste, and a shortness of aftertaste length. CV wine showed very close sensory characters to control in most terms evaluated. Seventy-four volatile compounds were quantitative analysed by solid phase microextractiongas chromatography-mass spectrometry, and the principal component analysis (PCA) was conducted on the 23 volatiles of highest odour activity value (OAV). The concentrations of potential fruity and floral aroma attributors like isoamyl acetate, ethyl butanoate, ethyl 2-methylbutanoate, ethyl hexanoate, ethyl octanoate, β-damascenone, and linalool were lower in HT wine than that in original wine and CV wine.