Low Temperature Storage Research Articles

Influence of host age and low-temperature storage on parasitization by the egg parasitoid Trissolcus japonicus (Hymenoptera: Scelionidae)

Influence of host age and low-temperature storage on parasitization by the egg parasitoid Trissolcus japonicus (Hymenoptera: Scelionidae)

Preparation and performance of reversible thermochromic phase change microcapsules based on negative photochromic spiropyran

Thermochromic phase change materials have been widely studied for their importance in energy-efficient buildings, thermal control clothing, and low-temperature energy storage. Herein, we successfully designed and synthesized a spiropyran compound with negative photochromic properties in a solid matrix, 3-(3′,3′-dimethyl-6,8-dinitrospiro[chromene-2,2′-indolin]−1′-yl) propyl methacrylate (SPMA), as a thermochromic dye. The synthesized spiropyran was copolymerized with methyl methacrylate (MMA) using photoinitiation, and then n-octadecane was encapsulated by the copolymer to prepare reversible thermochromic phase change microcapsules (TC-microPCMs) through the solvent evaporation technique. The encapsulation efficiency of n-octadecane by copolymers prepared with different photoinitiator concentrations was also investigated. According to the results of SEM, particle size analysis (DLS), and DSC, the copolymer prepared at 3% concentration possessed the best encapsulation effect on n-octadecane, and the melting enthalpy of the microcapsules reached 168.7 J/g and the encapsulation ratio was 89.5%, which was not significantly different from that of microcapsules without the addition of thermochromic dyes. This di-functionalization process effectively avoids the "impurity effect" of dye addition. In addition, the homogeneous spherical structure and stable chemical composition of the microcapsules are the key factors to achieve a fully reversible thermochromic behavior. What's more, the functionalized film based on TC-microPCMs, TC-microPCMs@PVA, was used to explore the potential for applications in thermal storage and temperature sensing. The results demonstrated that the composite film has excellent reversible thermochromic performance, high latent heat storage performance, and good cycling durability, which make the bifunctional microcapsules highly promising candidates for thermal sensors, solar energy storage, and smart textiles.

Piezoelectric 1T Phase MoSe2 Nanoflowers and Crystallographically Textured Electrodes for Enhanced Low-Temperature Zinc-Ion Storage.

Transition metal dichalcogenides (TMDs) are regarded as promising cathode materials for zinc-ion storage owing to their large interlayer spacings. However, their capabilities are still limited by sluggish kinetics and inferior conductivities. In this study, a facile one-pot solvothermal method is exploited to vertically plant piezoelectric 1T MoSe2 nanoflowers on carbon cloth (CC) to fabricate crystallographically textured electrodes. The self-built-in electric field owing to the intrinsic piezoelectricity during the intercalation/deintercalation processes can serve as an additional piezo-electrochemical coupling accelerator to enhance the migration of Zn2+ . Moreover, the expanded interlayer distance (9-10Å), overall high hydrophilicity, and conductivity of the 1T phase MoSe2 also promoted the kinetics. These advantages endow the tailored 1T MoSe2 /CC nanopiezocomposite with feasible Zn2+ diffusion and desirable electrochemical performances at room and low temperatures. Moreover, 1T MoSe2 /CC-based quasi-solid-state zinc-ion batteries are constructed to evaluate the potential of the proposed material in low-temperature flexible energy storage devices. This work expounds the positive effect of intrinsic piezoelectricity of TMDs on Zn2+ migration and further explores the availabilities of TMDs in low-temperature wearable energy-storage devices.

Transcriptome analysis reveals the potential mechanism of carotenoids change in hepatopancreas under low-temperature storage from swimming crab (Portunus trituberculatus)

The hepatopancreas of swimming crab (Portunus trituberculatus) rich in carotenoids would undergo serious color deterioration during cold storage, and then made portunid lose its commodity value. In this study, we firstly elucidated the change mechanism of its carotenoids during storage at the molecular level using transcriptome technology. We concluded that low-temperature would inhibit aerobic respiration of portunid, leading to a lower pH and inducing the degradation of carotenoids. After that, longer cold storage time would increase the oxidative stress in portunid, resulting in a further decrease in carotenoids content. Finally, the strong autolysis of portunid could release carotenoids stored in other parts such as ovary to the external environment, resulting in the increase of carotenoids detection content. This research could provide a basis for further developing the fresh-keeping technology of portunid during low-temperature storage.

Investigating suitable medium for the long-duration storage of Ti2CTx MXene

Recently, 2D material MXene gained a significant attention due to its unique properties like chemical diversity, hydrophilicity, 2D morphology, metallic conductivity, etc. Despite the promising properties of MXenes, these materials are not gaining momentum in various applications because of their poor chemical or oxidation stability. Earlier reports stated that organic solvents with low temperature storage could prevent the oxidation of Ti3C2Tx MXene flakes due to less number of dissolved oxygen molecules in the solvents. Due to the lack of a suitable storage media, Ti2CTx MXene is still receiving less attention despite having equivalent physio-chemical properties to Ti3C2Tx. To address this issue, this paper reports a suitable medium for preventing or delaying the degradation or oxidation of Ti2CTx MXene. Herein, Ti2CTx MXene was dispersed in different solvents for a duration of 3 months at ambient (room temperature) and freezing conditions (−20 °C and −80 °C) and characterized thereafter using XRD, Raman, SEM, TEM and XPS techniques. The results are suggested that polar solvents with a high surface tension, high viscosity, high boiling point, and high dielectric constant and in case of “Dry MXene”, keep it in a vacuum or inert atmosphere, will be suitable for long duration storage of Ti2CTx MXene at room temperature. However, it is not the best option for storing the material for a long duration of time. Finally, we have successfully find out the suitable storage medium to avoid the degradation and oxidation of Ti2CTx MXene for a long period of time and it is recommended that it should be dispersed in polar solvents and stored in a frozen condition like − 20 °C temperature or below (−80 °C). In case of “Dry MXene”, the storage condition should be at subzero temperature (−20 °C), and/or freezing conditions should be maintained to avoid degradation as well as oxidation.

The Regulatory Mechanisms and Control Technologies of Chilling Injury and Fungal Diseases of Postharvest Loquat Fruit.

Loquat is a popular fruit widely cultivated all over the world. It is rich in minerals and carotenoids and has high commercial value. At room temperature, loquat fruit is impressionable to water and nutritional losses, physical damage, and microbial decay, resulting in a short postharvest life. Low-temperature storage is routinely used to prolong the shelf life of loquat fruit; however, cold storage can also lead to lignification of flesh tissue, which is one of the major symptoms of chilling injury (CI), reducing the quality and economic value of the fruit. In addition, fruit decay caused by microbial infection is another important reason for postharvest losses of loquat. To reduce quality deterioration and optimize the postharvest storage strategies of loquat fruit, considerable progress has been made in the physiological and molecular biological studies of CI, microbial decay, and preservation technologies of loquat fruit during the postharvest phase in recent decades. This review summarizes the current research progress and provides a reference for the improvement of loquat fruit quality.

Quality changes and indicator proteins of Litopenaeus vannamei based on label-free proteomics analysis during partial freezing storage

Litopenaeus vannamei are known to deteriorate in quality during low-temperature storage. This study demonstrated the potential protein indicators of partial freezing of stored shrimp by traditional quality parameters and label-free based proteomic techniques. The carbonyl content and myofibril fragmentation index (MFI) of shrimp increased from 0.56 ± 0.03 to 2.14 ± 0.03 nmol/mg and 13.09 ± 0.14 to 54.93 ± 0.96, respectively. Within the extension of storage, the trichloroacetic acid (TCA), cooking loss and whiteness significantly increased. A total of 240 proteins changed in abundance at 10, 20, and 30 days compared to fresh samples. Projectin, ribosomal protein and histone were potential biomarkers for protein denaturation and oxidation in shrimp muscle. Myosin heavy chain and glyceraldehyde-3-phosphate dehydrogenase corresponded with the degradation of muscle proteins. Myosin light chain, tubulin alpha chain, and heat shock protein correlated with tenderness and water holding capacity; meantime, malate dehydrogenase and hemocyanin can serve as color indicators. Further study of the properties of these indicator proteins can inform their exploitation as quality indicator proteins during partial freezing storage.

A facile complexing chemical reduction for the preparation of Sn/graphene nanocomposites and their high performance for lithium-ion batteries

The pursuit of simpler and more efficient methods for the preparation of high-performing lithium-storage materials is always considered to be an important job for researchers interested in lithium-ion batteries. Herein, a facile complexing chemical reduction strategy is successfully developed for the preparation of newly advanced Sn/graphene (Sn/G) nanocomposite as anode material LIBs. The complexing reagent of ethylenediamine tetraacetate disodium (EDTA-2Na) and reducing agent of NaBH4 added in the preparation process are both found to play pivotal roles in the controllable reduction of Sn2+ and formation of highly conductive graphene matrix. The Sn/G nanocomposite exhibits a loosely stacked structure with ultrafine Sn nanoparticles (20–40 nm) uniformly dispersing on graphene nanosheets. This specially designed morphology is proved to be beneficial for electrolyte infiltrating and highly efficient transport of Li-ions. The Sn/G nanocomposite displays outstanding lithium storage up to 1032 mAh g−1 after 150 cycles and a high rate performance of 535 mAh g−1 at 1 A g−1. The highly conductive and flexible network of graphene effectively alleviates the small absolute volume expansion of ultrafine Sn nanoparticles and maintains the structure stability. In addition, a fair low-temperature performance of 322 mAh g−1 at − 20 °C was also achieved due to the excellent structural features of the Sn/G nanocomposite. The work has managed to provide a simple and reliable method for the synthesis of Sn/C material as well as a potential candidate for low-temperature lithium storage applications.

The Impact of Baffle Geometry in the PCM Heat Storage Unit on the Charging Process with High and Low Water Streams

This paper presents the effect of baffle geometry on the charging process of a low-temperature heat storage unit. Four different geometry variants were considered for this purpose. Each of them was simulated and the results were compared. The following parameters were selected as comparison criteria: the charging time of the heat storage unit, the change in the liquid and solid fractions of the phase change material, and the change in its temperature over time. The analysis showed that, independent from the heat transfer fluid velocity, the use of baffles did not significantly affect the charging time. Furthermore, the application of baffles of all studied types did not bring an essential decrease in charging time. It was found that the optimal solution was to use the simplest construction. Tuning of the HTF flow by the use of baffles is applicable to shell and tube heat exchangers; however, it adds no significant effects in the case of heat storage units of the proposed design. The abovementioned effect has been explained by the heat flux analysis, which shows that the heat transfer in the PCM is radically less intense, when comparing to the working fluid. Therefore, it is expected that enhancing the heat transfer between HTF and PCM material is possible by modifying the PCM–side design.

Changes in Polyphenolic Compounds of Hutai No. 8 Grapes during Low-Temperature Storage and Their Shelf-Life Prediction by Identifying Biomarkers.

The aim of this experiment was to assess the effect of different storage temperatures on the texture quality, phenolic profile, and antioxidant capacity of a grape. Fresh grapes were stored at 4 and 25 °C for nine days and sampled on alternate days. The hardness, total phenolics, total flavanones, total flavanols, total anthocyanin content, antioxidant activity, differential metabolite screening, and key gene expression were evaluated. In addition, four phenolic compounds were screened out as differential metabolites in response to storage temperature by OPLS-DA analysis. The results showed that the fruit firmness was better maintained in low-temperature storage and the storage life was longer than that at 25 °C. During the whole storage process, the contents of phenolics, flavanones, flavanols, and anthocyanins all showed an increasing trend first and then decreased regardless of what temperature. Since the antioxidant capacity of a grape was positively correlated with the contents of total phenols and total flavonoids, the same trend was also shown. However, the grape's phenolic compound content and antioxidant activity were higher at 25 °C than at 4 °C. Furthermore, through qualitative and quantitative analysis of 16 monomeric phenols, this study selected catechin, 1-O-vanilloyl-β-d-glucose, p-coumaric acid 4-glucoside, and resveratrol-3-O-glucoside as the main differentially expressed metabolites at the two temperatures. In conclusion, for a short shelf life or immediate consumption, keeping grapes at room temperature is more beneficial to obtain high antioxidants. However, if the goal is to prolong the storage period of the fruit, keeping the fruit at 4 °C is recommended.

Melatonin Treatment Affects Wax Composition and Maintains Storage Quality in 'Kongxin' Plum (Prunus salicina L. cv) during Postharvest.

Cuticular wax is an essential barrier against biological and abiotic stress and is also an important factor affecting fruit storage quality. This paper investigated the effect of melatonin treatment on cuticular wax and the storage quality of plum fruit at low temperature storage of 4 ± 1 °C. 'Kongxin' plum was treated with 150 μmol·L-1 melatonin, dried overnight at room temperature 25 ± 1 °C, and then stored at 4 ± 1 °C for 40 d. The microstructure of the fruit epidermis was examined after 0, 20, and 40 d of storage, and the wax composition and fruit storage quality were measured at 10 d intervals. The results demonstrated that melatonin promoted the disintegration and thickening of rod-shaped waxy crystals of 'Kongxin' plum fruit and inhibited the combination of disintegrated wax and inner wax. Melatonin maintained fruit firmness and decreased the correlation between fruit firmness and other storage quality parameters. The correlation between firmness and wax composition was enhanced. Melatonin promoted long-chain alkanes that were positively correlated with firmness and water retention and strengthened the correlation between the length of the alkane chain and storage quality parameters but reduced the difference between alkane isomers and storage quality parameters.

Mechanistic Study of Diketopiperazine Formation during Solid-Phase Peptide Synthesis of Tirzepatide.

This study focused on investigating diketopiperazine (DKP) and the formation of associated double-amino-acid deletion impurities during linear solid-phase peptide synthesis (SPPS) of tirzepatide (TZP). We identified that the DKP formation primarily occurred during the Fmoc-deprotection reaction and post-coupling aging of the unstable Fmoc-Pro-Pro-Ser-resin active pharmaceutical ingredient (API) intermediate. Similar phenomena have also been observed for other TZP active pharmaceutical ingredient (API) intermediates that contain a penultimate proline amino acid, such as Fmoc-Ala-Pro-Pro-Pro-Ser-resin, Fmoc-Pro-Pro-Pro-Ser-resin, and Fmoc-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser-resin, which are intermediates for both hybrid and linear synthesis approaches. During post-coupling aging, it is found that Fmoc deprotection can proceed in dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), and acetonitrile (ACN) solvents without any piperidine addition. Density functional theory (DFT) calculations showed that a peptide that has a penultimate proline stabilizes the transition state through the C-H···π interaction during Fmoc decomposition, which causes those peptides to be more prone to cascade-deprotection reactions. Pseudo-reaction pathways are then proposed, and a corresponding macrokinetics model is developed to allow accurate prediction of the TZP peptide intermediate self-deprotection and DKP formation rate. Based on those studies, control strategies for minimizing DKP formation were further investigated and an alternative to Fmoc protection was identified (Bsmoc-protected amino acids), which eliminated the formation of the DKP byproducts. In addition, the use of oxyma additives and lower storage temperature was demonstrated to markedly improve the peptide intermediate stability to DKP degradation pathways.

Parametric study of low-temperature thermal energy storage using carbon dioxide as the phase change material in pillow plate heat exchangers

Industrial low-temperature freezing applications are often batch processes, requiring a lot of energy, exerting stress on the electrical grid. To relieve this stress, thermal energy storage can be used. However, there is a lack of suitable storage material for low temperature applications (around −50 °C). Under high pressures, carbon dioxide can be used as the phase change material for storage temperatures around −55 °C. In this study, a parametric study was conducted on the design and operational parameters of an industrial-scale pillow plate heat exchanger with carbon dioxide. Two responses were selected for the analysis where R1 considered the storage size over the phase change time (kWh/h), while R2 indicated the cost over the storage size (USD/kWh). Using design of experiments, a total of 52 simulations were carried out to investigate the parameters under constant heat transfer surface area. Analysis of variance was then carried out followed by correlation development and optimization. It was found that regardless of the process (charging or discharging), for R1 and R2, the difference between refrigerant and carbon dioxide phase change temperatures followed by plate material had the highest significance. In contrast, the refrigerant flow rate had the lowest significance in almost all cases. Moreover, considering an equal weight for the responses, overall optimal conditions were determined for the processes. The recommended values for plate pitch, plate material, difference between refrigerant and carbon dioxide phase change temperatures and refrigerant flow rate were 25 mm, aluminum, 15 °C and 4 kg/s, respectively.

An aqueous magnesium-ion battery working at −50 °C enabled by modulating electrolyte structure

The earth-abundant magnesium resource and aqueous electrolyte make aqueous magnesium-ion batteries (AMIBs) a promising post-lithium-ion battery technology to synchronously address cost and safety concerns. Nonetheless, the freeze issue of aqueous electrolytes is curbing the development of AMIBs working at low-temperature conditions. Here, we report an MgCl2 solution having a great low-temperature property via anion and concentration adjustment, which roots in the variation of the pristine hydrogen bond reticulation. Consequently, a 4 M MgCl2 aqueous electrolyte endows a low freezing point (−62 °C) as well as ultra-high ionic conductivity (2.77 mS/cm at −50 °C). By using 4 M MgCl2 as an electrolyte, the MnO2//VO2 battery is capable of working in a wide temperature range from +25 to −50 °C, achieving a high discharge capacity of 97.9 mAh/g (0.1 A/g) and a high cycling capability of 1000 cycles (∼90 % capacity retention at −20 °C). Furthermore, MgCl2 can be well compatible with polyacrylamide into an outstanding hydrogel electrolyte (in terms of mechanical property, anti-freeze performance, and high ionic conductivity) for a flexible quasi-solid-state MIBs application. The assembled flexible device attains appealing electrochemical properties across a broad temperature region, while the constructed pouch cell demonstrates superior flexibility and reliable safety. Our current exploration depicts an expeditious but productive paradigm for devising the high-performing AMIBs for low-temperature energy storage sectors.

Postharvest chitosan-arginine nanoparticles application ameliorates chilling injury in plum fruit during cold storage by enhancing ROS scavenging system activity

BackgroundPlum (Prunus domestica L.) has a short shelf-life period due to its high respiration rate and is sensitive to low storage temperatures, which can lead to the appearance of chilling injury symptoms. In this investigation, we applied new coating treatments based on chitosan (CTS) and arginine (Arg) to plum fruit (cv. ‘Stanley’).ResultsFruit were treated with distilled water (control), Arg at 0.25 and 0.5 mM, CTS at 1% (w/v) or Arg-coated CTS nanoparticles (CTS-Arg NPs) at 0.5 and 1% (w/v), and then stored at 1 °C for days. The application of CTS-Arg NPs at 0.5% attenuated chilling injury, which was accompanied by accumulation of proline, reduced levels of electrolyte leakage and malondialdehyde, as well as suppressed the activity of polyphenol oxidase. Plums coated with CTS-Arg NPs (0.5%) showed higher accumulation of phenols, flavonoids and anthocyanins, due to the higher activity of phenylalanine ammonia-lyase, which in turn resulted in higher DPPH scavenging capacity. In addition, CTS-Arg NPs (0.5%) treatment delayed plum weight loss and retained fruit firmness and ascorbic acid content in comparison to control fruit. Furthermore, plums treated with CTS-Arg NPs exhibited lower H2O2 accumulation than control fruit due to higher activity of antioxidant enzymes, including CAT, POD, APX and SOD.ConclusionsThe present findings show that CTS-Arg NPs (0.5%) were the most effective treatment in delaying chilling injury and prolonging the shelf life of plum fruit.

Shotgun proteomics of Nanicão and Prata bananas reveals changes that may account for their different resistance to low temperature

Low-temperature storage has been widely used to extend the post-harvest life of many fruits. However, tolerance to cold is largely variable even among different fruit cultivars. In this regard, the banana cultivars Nanicão and Prata display different responses to low-temperature storage. Prata is less affected by cold storage, while the synthesis of volatiles is drastically reduced in Nanicão bananas. Therefore, this study aimed to investigate the effect of low temperature storage at the proteome level using a shotgun proteomics approach to identify a large number of proteins in these banana varieties. Seventy-four differentially expressed proteins were identified in cv. Prata and 43 in cv. Nanicão. Principal component analysis indicated that samples from control and cold storage groups could be differentiated based on their proteome. Overall, low temperatures decreased proteins related to carbohydrate metabolism and energy, defense, and transport in Nanicão bananas. Contrastingly, low temperatures induced the accumulation of proteins for carbohydrate metabolism and energy, transport, and defense in Prata bananas. Therefore, the observed changes in the proteome during cold acclimation and ripening in Nanicão and Prata bananas can explain, at least in part, the differences in low-temperature tolerance between these cultivars.

Impacto de dos tratamientos hidrotérmicos aplicados secuencialmente sobre el metabolismo oxidativo relacionado con la tolerancia al daño por frío en frutos de mango

Mango is susceptible to chilling injury (CI). Its short-term exposure to heat treatments can induce tolerance to this disorder; however, a short time is not enough to control the fruit fly. In this sense, the application of sequential heat treatments where the quarantine treatment is included can bring great benefits for mango marketing. The aim of this research was to evaluate the effect of two different sequentially-applied hot water treatments (HWT) on CI tolerance and changes in oxidative metabolism in mango. Mangoes were divided into four groups: control, HWT1 (dipping in water at 46.1 °C for 75 min), HWT2 (dipping in water at 55 °C for 5 min), and HWT1 + HWT2. Fruits were stored at 5 °C/30 days to induce CI and thereafter at 21 °C for 8 days. Three replicates with five repetitions were used to evaluate CI index, electrolyte leakage (EL), malondialdehyde (MDA), weight loss (WL), color, firmness and enzymatic antioxidant activity. The use of HWT1 reduced CI during low temperature storage, while HWT2 and the HWT1 + HWT2 showed lower CI symptoms during ripening. The use of HWT1 showed a similar EL % and higher MDA content (7.07 x 104 nmol·L-1) than the control (6.68 x 104 nmol·L-1). HWT1 + HWT2 showed the lowest WL (2.98 %) and the highest enzymatic antioxidant activity during cold storage and during the first days at 21 °C, while HWT2 showed the highest color and firmness retention. Hot water treatments applied sequentially can be considered an effective alternative to induce CI tolerance and to maintain the quality of mango.

Ultrasound-assisted green synthesis of Ru supported on LDH-CNT composites as an efficient catalyst for N-ethylcarbazole hydrogenation.

N-ethylcarbazole/dodecahydro-N-ethylcarbazole (NEC/12H-NEC) is one of the most attractive LOHCs, and it is of great significance to develop catalysts with high activity and reduce the hydrogen storage temperature. Layered double hydroxides-carbon nanotubes composites (LDH-CNT) were synthesized by a simple in-situ assembly method. Due to the introduction of CNT, a strong interaction occurred between LDH and CNT, which effectively improved the electron transfer ability of LDH-CNT. Ru/LDH-CNT catalysts were prepared via ultrasound-assisted reduction method without adding reducing agents and stabilizers. Under the cavitation effect of ultrasound, the hydroxyl groups on the surface of LDH were excited to generate hydrogen radicals (•H) with high reducibility, which successfully reduced Ru3+ to Ru NPs. Ru/LDH-3.9CNT-(300-1) catalyst was of 1.63nm average Ru particle size with CNT amount of 3.9wt% and the ultrasonic power of 300W at 1h, and its electron transfer resistance was less than that of Ru/LDH-(300-1). The synergy of ultrafine Ru NPs and fast electron transfer made it exhibit exceptional catalytic performance in NEC hydrogenation. Even if the reaction temperature was lowered to 80°C, its hydrogenation performance was better than that of commercial Ru/Al2O3 catalyst at 120°C. The ultrasound-assisted method is efficient, green and environmentally friendly, and the operation process is simple and economical. It is expected to be used in practical industrial production, which provides a reference for the preparation of high-activity and low-temperature hydrogen storage catalysts.

Carnot battery system integrated with low-grade waste heat recovery: Toward high energy storage efficiency

The low-grade waste heat is widely distributed in various scenarios and lacks suitable technologies for recovery. Carnot battery is a large-scale electrical energy storage technology, and pumped thermal energy storage (PTES) is one of the branches in which the waste heat can be efficiently utilized. The integration of the PTES system and waste heat promotes energy storage efficiency and tackles the problem of low-grade waste heat utilization. Aiming to improve the energy storage efficiency of the system, several PTES systems have been put forward, where the system configurations were modified and the waste heat is employed in both the heat pump cycle and the organic Rankine cycle. The novel concept of the PTES systems was examined, and the energy-conservation mechanism was further explored. Moreover, the effect of the heat storage temperature pair on the PTES system was evaluated, and the results indicate that the highest efficiency can attain when the low heat storage temperature is around 100.0 °C. The implementation of different working fluids in the charging and discharging process leads to the promotion of power-to-power efficiency, and the efficiency increases from 65.56 % to 66.52 % when the high heat storage temperature is chosen as 130 °C. In terms of various waste heat parameters, the power-to-power efficiency of the advanced PTES system can attain 99.3 % as the inlet temperature of the waste heat rises to 90.0 °C.

Differences in commercial quality and carotenoids profile of yellow- and white-fleshed nectarine fruit during low temperature storage and the regulation of carotenoids by sugar

The aim of this study was to assess commercial quality parameters, carotenoids and sugars in two different nectarine cultivars (‘Zijinhong’, yellow flesh, and ‘Ruiguang’, white flesh) to gain insight into their commercial quality differences and the interaction among carotenoid, glucose, sucrose and fructose in nectarines during low temperature storage. In comparison with the white-fleshed cultivar ‘Ruiguang’, higher storability by higher soluble solid content and slower decrease of fruit firmness were exhibited in yellow-fleshed ‘Zijinhong’ nectarine. The increased carotenoids accumulation and inhibition of glucose and fructose degradation occurred in both cultivars, and glucose were positively correlated with total carotenoid contents (0.9825). It was confirmed through an in vitro test that glucose and fructose induced the biosynthesis of carotenoids. In addition, the gene expression of phytoene synthase and carotenoid cleavage dioxygenase were highly correlated with carotenoid content in ‘Zijinhong’ nectarine flesh.