More opportunities more species: Pleistocene differentiation and northward expansion of an evergreen broad-leaved tree species Machilus thunbergii (Lauraceae) in Southeast China.

BACKGROUND: The broad continuum between tropical and temperate floras in Eastern Asia (EAS) are thought to be one of the main factors responsible for a prominent species diversity anomaly of temperate plants between EAS and eastern North America (ENS). However, how the broad continuum and niche evolution between tropical and temperate floras in EAS contributes to lineage divergence and species diversity remains largely unknown. RESULTS: Population genetic structure, demography, and determinants of genetic structure [i.e., isolation-by-distance (IBD), isolation-by-resistance (IBR), and isolation-by-environment (IBE)] of Machilus thunbergii Sieb. et Zucc. (Lauraceae) were evaluated by examining sequence variation of ten low-copy nuclear genes across 43 populations in southeast China. Climatic niche difference and potential distributions across four periods (Current, mid-Holocene, the last glacial maximum, the last interglacial) of two genetic clusters were determined by niche modelling. North and south clusters of populations in M. thunbergii were revealed and their demarcation line corresponds well with the northern boundary of tropical zone in China of Zhu & Wan. The divergence time between the clusters and demographic expansion of M. thunbergii occurred after the mid-Pleistocene climate transition (MPT, 0.8-1.2 Ma). Migration rates between clusters were asymmetrical, being much greater from north to south than the reverse. Significant effects of IBE, but non-significant effects of IBD and IBR on population genetic divergence were detected. The two clusters have different ecological niches and require different temperature regimes. CONCLUSIONS: The north-south genetic differentiation may be common across the temperate-tropical boundary in southeast China. Divergent selection under different temperature regimes (possibly above and below freezing temperature in winter) could account for this divergence pattern. The broad continuum between tropical and temperate floras in EAS may have provided ample opportunities for tropical plant lineages to acquire freezing tolerance and to colonize the temperate regions during the late-Cenozoic global cooling. Our findings shed deeper insights into the high temperate plant species diversity in EAS.

Effect of freezing temperature on dewatering, consolidation properties, and microstructure of landfill sludge.

There is currently a considerable amount of landfill sludge (LS) accumulating worldwide, threatening the surrounding environment and land safety. It is urgent to dewater and reduce LS. Chemical conditioning is the most common treatment for LS, which can pollute the environment and limit resource exploitation. Therefore, a more environmentally friendly and efficient freeze-thaw combined vacuum preloading method is proposed. Experimental studies were conducted to investigate the influence of different freezing temperatures on the dewatering properties, compression and consolidation features, and the mechanism of microstructural change in LS. The results show that the freezing temperature has an important influence on the dewatering, compression, vacuum drainage, consolidation, and microstructure characteristics of LS. The compressibility of LS does not improve when the freezing rate is too high. Freeze-thaw cycles can improve sludge's permeability and consolidation properties by one to two orders of magnitude, and a suitable freezing temperature can significantly improve sludge's permeability and consolidation properties. After vacuum drainage and consolidation, the maximum volume reduction ratio of sludge can reach 55.3%, and the water content of LS can be reduced from 86% to 66%. The distribution of large pores and mesopores in LS increases as the freezing temperature decreases, reaching a maximum of -15 °C, which can substantially improve permeability, drainage, and consolidation efficiency.

Micro-fluidic Spray Freeze Dried Ciprofloxacin Hydrochloride-Embedded Dry Powder for Inhalation.

Active pharmaceutical ingredient (API)-embedded dry powder for inhalation (AeDPI) is highly desirable for pulmonary delivery of high-dose drug. Herein, a series of spray freeze-dried (SFD) ciprofloxacin hydrochloride (CH)-embedded dry powders were fabricated via a self-designed micro-fluidic spray freeze tower (MFSFT) capable of tuning freezing temperature of cooling air as the refrigerant medium. The effects of total solid content (TSC), mass ratio of CH to L-leucine (Leu) as the aerosol dispersion enhancer, and the freezing temperature on particle morphology, size, density, moisture content, crystal properties, flowability, and aerodynamic performance were investigated. It was found that the Leu content and freezing temperature had considerable influence on the fine particle fraction (FPF) of the SFD microparticles. The optimal formulation (CH/Leu = 7:3, TSC = 2%w/w) prepared at - 40°C exhibited remarkable effective drug deposition (~ 33.38%), good aerodynamic performance (~ 47.69% FPF), and excellent storage stability with ultralow hygroscopicity (~ 1.93%). This work demonstrated the promising feasibility of using the MFSFT instead of conventional liquid nitrogen assisted method in the research and development of high-dose AeDPI.

Removal of astringency in persimmon fruits (Diospyros kaki) subjected to different freezing temperature treatments.

The effects of two different freezing temperatures (- 20 °C and - 80 °C) on the astringency trait of persimmon fruits during 15 to 60 days of storage were investigated. The levels of soluble and insoluble tannins, proanthocyanidins and other physicochemical characteristics were evaluated. Storage at - 20 °C and - 80 °C temperatures up to 60 days has been found to be an effective method to remove astringency of persimmon fruits. Proanthocyanidin concentration was negligible at both temperatures during storage. Total soluble solid contents were decreased as 3.34 from 4.59 (mg/g DW) whereas, insoluble tannin contents were increased as 20.30 from 16.45 (mg/g DW) by freezing temperatures treatment during storage. Comparatively, higher soluble tannin content 11.68 (mg/g DW) and lower insoluble tannin content 10.02 (mg/g DW) was observed in control (day 0). Therefore, the astringency of persimmon fruits incubated at - 20 °C and - 80 °C was markedly reduced and after 15 up to 60 days of storage, the astringent taste virtually disappeared. The proanthocyanidin contents were decreased as 0.02 from 0.52 (mg/g DW) at - 20 °C storage and 0.17 from 0.47 (mg/g DW) at - 80 °C storage, in comparison with the control 2.65 (mg/g DW). The moreover, along with the removal of astringency, other physicochemical parameters including color, pH, moisture content, total soluble solid, and sensory attributes were also conserved on freezing at both the temperatures. These findings suggest that freezing temperature treatments aid the removal of astringency from persimmon fruits which could be used in different food preparations or as supplements.

Influence of freezing temperature before freeze-drying on the viability of various Lactobacillus plantarum strains.

Although freeze-drying is an excellent method for preserving microorganisms, it inevitably reduces cell activity and function. Moreover, probiotic strains differ in terms of their sensitivity to the freeze-drying process. Therefore, it is necessary to optimize the variables relevant to this process. The pre-freezing temperature is a critical parameter of the freeze-drying process, but it remains unclear whether the optimal pre-freezing temperature differs among strains and protectants. This study explored the effects of 4 different pre-freezing temperatures on the survival rates of different Lactobacillus plantarum strains after freeze-drying in the presence of different protectants. Using phosphate-buffered saline solution and sorbitol as protectants, pre-freezing at -196°C, -40°C, and -20°C ensured the highest survival rates after freeze-drying for AR113, AR307, and WCFS1, respectively. Using trehalose, pre-freezing at -20°C ensured the best survival rate for AR113, and -60°C was the best pre-freezing temperature for AR307 and WCFS1. These results indicate that the pre-freezing temperature can be changed to improve the survival rate of L. plantarum, and that this effect is strain-specific. Further studies have demonstrated that pre-freezing temperature affected viability via changes in cell membrane integrity, membrane permeability, and lactate dehydrogenase activity. In summary, pre-freezing temperature is a crucial factor in L. plantarum survival after freeze-drying, and the choice of pre-freezing temperature depends on the strain and the protectant.

Impacts of Freezing Temperature Based Thermal Conductivity on the Heat Transfer Gradient in Nanofluids: Applications for a Curved Riga Surface.

The flow of nanofluid over a curved Riga surface is a topic of interest in the field of fluid dynamics. A literature survey revealed that the impacts of freezing temperature and the diameter of nanoparticles on the heat transfer over a curved Riga surface have not been examined so far. Therefore, the flow of nanoparticles, which comprises the influences of freezing temperature and nanoparticle diameter in the energy equation, was modeled over a curved Riga surface. The model was reduced successfully in the nondimensional version by implementing the feasible similarity transformations and effective models of nanofluids. The coupled nonlinear model was then examined numerically and highlighted the impacts of various flow quantities in the flow regimes and heat transfer, with graphical aid. It was examined that nanofluid velocity dropped by increasing the flow parameters γ and S, and an abrupt decrement occurred at the surface of the Riga sheet. The boundary layer region enhances for larger γ. The temperature distribution was enhanced for a more magnetized nanofluid, and the thermal boundary layer increased with a larger R parameter. The volume fraction of the nanoparticles favors the effective density and dynamic viscosity of the nanofluids. A maximum amount of heat transfer at the surface was observed for a more magnetized nanofluid.

Radiative Colloidal Investigation for Thermal Transport by Incorporating the Impacts of Nanomaterial and Molecular Diameters (dNanoparticles, dFluid): Applications in Multiple Engineering Systems.

Thermal enhancement and irreversible phenomena in colloidal suspension (Al2O3-H2O) is a potential topic of interest from the aspects of industrial, mechanical and thermal engineering; heat exchangers; coolant car radiators; and bio-medical, chemical and civil engineering. In the light of these applications, a colloidal analysis of Al2O3-H2O was made. Therefore, a colloidal model is considered and treated numerically. The significant influences of multiple parameters on thermal enhancement, entropy generation and Bejan parameter are examined. From the presented colloidal model, it is explored that Al2O3-H2O is better for the applications of mechanical and applied thermal engineering. Moreover, fraction factor tiny particles are significant parameters which enhanced the thermal capability of the Al2O3-H2O suspension.

Role of synthetic antifreeze agents in catalyzing ice nucleation.

Nature endows antifreeze (glyco)proteins (AF(G)Ps) with the excellent capability of inhibiting ice crystal growth. Recent years have also witnessed the emergence of many potent AF(G)P mimics such as poly (vinyl alcohol) (PVA). As researchers are revealing the molecular mechanisms of inhibiting ice crystal growth by AF(G)Ps and their synthetic substitutes, there remains no agreement about their effect on ice nucleation. In this study, we report the observation of ice nucleation catalyzed by PVA of different polymerization degrees using a freeze-on-a-chip platform which allows the monitoring of freezing and melting events over hundreds of monodisperse, picoliter-sized aqueous droplets. Aqueous droplets made of 1 mg/ml PVA solution exhibit a median freezing temperature of around -36 °C, two degrees higher than the observed homogeneous nucleation temperature of water. The findings in our study bring useful insights into the different roles of synthetic antifreeze agents in controlling ice formation.

Drought increases the freezing resistance of high-elevation plants of the Central Chilean Andes.

Freezing temperatures and summer droughts shape plant life in Mediterranean high-elevation habitats. Thus, the impacts of climate change on plant survival for these species could be quite different to those from mesic mountains. We exposed 12 alpine species to experimental irrigation and warming in the Central Chilean Andes to assess whether irrigation decreases freezing resistance, irrigation influences freezing resistance when plants are exposed to warming, and to assess the relative importance of irrigation and temperature in controlling plant freezing resistance. Freezing resistance was determined as the freezing temperature that produced 50 % photoinactivation [lethal temperature (LT50)] and the freezing point (FP). In seven out of 12 high-Andean species, LT50 of drought-exposed plants was on average 3.5 K lower than that of irrigated plants. In contrast, most species did not show differences in FP. Warming changed the effect of irrigation on LT50. Depending on species, warming was found to have (1) no effect, (2) to increase, or (3) to decrease the irrigation effect on LT50. However, the effect size of irrigation on LT50 was greater than that of warming for almost all species. The effect of irrigation on FP was slightly changed by warming and was sometimes in disagreement with LT50 responses. Our data show that drought increases the freezing resistance of high-Andean plant species as a general plant response. Although freezing resistance increases depended on species-specific traits, our results show that warmer and moister growing seasons due to climate change will seriously threaten plant survival and persistence of these and other alpine species in dry mountains.

Influence of Pre-Freezing Temperature on the Corneal Endothelial Cytocompatibility and Cell Delivery Performance of Porous Hyaluronic Acid Hydrogel Carriers.

The development of porous hyaluronic acid (HA) hydrogels for corneal endothelial tissue engineering is attractive because they can be used as functional cell delivery carriers to help in the reconstruction of damaged areas. The purpose of this study was to investigate the corneal endothelial cytocompatibility and cell delivery performance of porous HA hydrogel biomaterials fabricated at different pre-freezing temperatures. As compared to their counterparts prepared at -80 °C, the HA samples fabricated at higher pre-freezing temperature (i.e., 0 °C) exhibited a larger pore size and higher porosity, thereby leading to lower resistance to glucose permeation. Live/dead assays and gene expression analyses showed that the restricted porous structure of HA carriers decreases the viability and ionic pump function of cultured corneal endothelial cells (CECs). The results also indicated that the porous hydrogel biomaterials fabricated at high pre-freezing temperature seem to be more compatible with rabbit CECs. In an animal model of corneal endothelial dysfunction, the wounded rabbit corneas receiving bioengineered CEC sheets and restricted porous-structured HA carriers demonstrated poor tissue reconstruction. The therapeutic efficacy of cell sheet transplants can be improved by using carrier materials prepared at high pre-freezing temperature. Our findings suggest that the cryogenic operation temperature-mediated pore microstructure of HA carriers plays an important role in corneal endothelial cytocompatibility and cell delivery performance.

Near-freezing temperature suppresses avocado (Persea americana Mill.) fruit softening and chilling injury by maintaining cell wall and reactive oxygen species metabolism during storage.

To enhance the postharvest quality of avocado (Persea americana Mill.) fruit, this study investigates alterations in cell wall metabolism and reactive oxygen species (ROS) metabolism during near-freezing temperature (NFT) storage, and explores their impact on fruit softening. The fruit was stored at 25 °C, 5 °C, 2 °C, and NFT, respectively. NFT storage retarded firmness loss and chilling injury in comparison with 25 °C, 5 °C, and 2 °C. NFT storage delayed the decrease of ionic-soluble pectin (ISP) and cellulose (CLL) contents by suppressing cell wall degradation enzyme activities. Correlation analysis showed that cell wall degradation enzyme activities were positively correlated to rates of ethylene release and respiration. Moreover, NFT storage maintained higher levels of DPPH and ABTS scavenging abilities, activities of superoxide dismutase, peroxidase, and catalase, as well as ascorbate-glutathione cycle (ascorbic acid, glutathione, glutathione disulfide, ascorbate peroxidase, cycle-related enzymes), thereby inhibited the increase of ROS content, malondialdehyde content, and cell membrane permeability. Fruit firmness and chilling injury were correlated with the contents of hydrogen (H2O2), superoxide anion (O2.-), ISP, and CLL. These results suggested that NFT could suppress fruit softening and chilling injury by inhibiting cell wall degradation through delaying respiration and ethylene production and suppressing ROS production via activation of antioxidant systems, thereby maintaining quality and prolonged storage life during avocado fruit storage.

Effects of freeze-thaw on bank soil mechanical properties and bank stability.

Riverbank instability in the seasonally frozen zone is primarily caused by freeze-thaw erosion. Using the triaxial freeze-thaw test on the bank of Shisifenzi Bend in the Yellow River section of Inner Mongolia, we investigated the changes in the mechanical properties of the soil at different freezing temperatures and freeze-thaw times, and analyzed the bank's stability before and after freezing based on the finite element strength reduction method. The results showed that the elastic modulus, cohesion, internal friction angle and shear strength of the soil tended to decrease with the increase in the number of freeze-thaw cycles and the decrease in freezing temperature. After 10 freezing cycles at - 5 â„ƒ, - 10 â„ƒ, - 15 â„ƒ and - 20 â„ƒ, the modulus of elasticity of soil decreased by 40.84 ~ 68.70%, the cohesion decreased by 41.96 ~ 56.66%, the shear strength decreased by 41.92 ~ 57.32%, respectively. Moreover, the stability safety coefficient of bank slope decreased by 18.58% after freeze-thaw, indicating that the freeze-thaw effect will significantly reduce the stability of bank slope, and the bank slope is more likely to be destabilized and damaged after freeze-thaw.

Influence of Temperature during Freeze-Drying Process on the Viability of Bifidobacterium longum BB68S.

Maintaining optimum temperature during freeze-drying is crucial to ensuring the viability of strains. In this study, we evaluated the effect of pre-freezing, sublimation and desorption temperatures on the viability of Bifidobacterium longum BB68S (BB68S). Moreover, we examined the water content, water activity, enzyme activities, and scanning electron microscope of BB68S to explore mechanisms underpinning the effect of temperature on viability. Our analyses revealed the highest survival rates of BB68S collected after pre-freezing and sublimation drying at -40 °C (94.9 ± 2.2%) and -10 °C (65.4 ± 3.8%), respectively. Additionally, response surface methodology demonstrated that the optimum conditions for freeze-drying of BB68S were pre-freezing temperature at -45.52 °C and sublimation temperature at -6.58 °C, and the verification test showed that survival rates of BB68S could reach 69.2 ± 3.8%. Most of the vitality loss occurred during the sublimation drying phase. Further studies showed that different sublimation temperatures affected water content and activity, ß-galactosidase, lactate dehydrogenase, Na+-K+-ATP and Ca2+-Mg2+-ATP activities. In conclusion, the temperature during freeze-drying, especially sublimation temperature, is a key factor affecting the survival rate of BB68S, and the vitality loss during freeze-drying process might be due to compromised cell membrane integrity and permeability.

Evaluation of Pressurized Steam Disinfection of Surfaces Contaminated by Mycobacterium terrae: A Surrogate for Mycobacterium bovis.

Introduction: Decontamination of farms affected by bovine tuberculosis could be very challenging during outbreaks occurring in the winter with freezing temperatures. Steam treatment has been of practical interest, but information is needed on whether such treatment is able to inactivate the causative agent, Mycobacterium bovis. This study was to evaluate the use of pressurized steam for inactivation of Mycobacterium terrae, a surrogate for M. bovis on various surfaces. Methods: Carrier disks made of steel, wood, or rubber were inoculated with 6.32 ± 0.38 log10 M. terrae. While being held at background temperatures of -20°C, 4°C, or 21°C, these carrier disks were treated with pressurized steam (120°C ± 5°C) for 5, 10, 15, or 20 s. Reduction in colony forming units of M. terrae and temperatures on the top and bottom surfaces of the disks were determined. Results: Complete inactivation of 6 log10 M. terrae on steel and wood disks was achieved by 10 s of steam treatment at all three background temperatures. In comparison, 20 s of steam treatment was needed for the complete inactivation of mycobacteria on rubber disks. Corresponding to the longer treatment time required for mycobacterial inactivation, temperatures on the bottom surface of the rubber disks rose substantially slower than those of the steel and wood disks at all three background temperatures. Conclusion: The results suggested that treatment with pressurized steam has potential for efficient and effective disinfection of surfaces contaminated by mycobacteria at or below freezing temperatures in winter.

Evidence of Formation of 1-10 nm Diameter Ice Nanotubes in Double-Walled Carbon Nanotube Capillaries.

Water exhibits rich phase behaviors in nanoscale confinement. Since the simulation evidence of the formation of single-walled ice nanotubes (INTs) in single-walled carbon nanotubes was confirmed experimentally, INTs have been recognized as a form of low-dimensional hydrogen-bonding network. However, the single-walled INTs reported in the literature all possess subnanometer diameters (<1 nm). Herein, based on systematic and large-scale molecular dynamics simulations, we demonstrate the spontaneous freezing transition of liquid water to single-walled INTs with diameters reaching ∼10 nm when confined to capillaries of double-walled carbon nanotubes (DW-CNTs). Three distinct classes of INTs are observed, namely, INTs with flat square walls (INTs-FSW), INTs with puckered rhombic walls (INTs-PRW), and INTs with bilayer hexagonal walls (INTs-BHW). Surprisingly, when water is confined in DW-CNT (3, 3)@(13, 13), an INT-FSW freezing temperature of 380 K can be reached, which is even higher than the boiling temperature of bulk water at atmospheric pressure. The freezing temperatures of INTs-FSW decrease as their caliber increases, approaching to the freezing temperature of two-dimensional flat square ice at the large-diameter limit. In contrast, the freezing temperature of INTs-PRW is insensitive to their diameter. Ab initio molecular dynamics simulations are performed to examine the stability of the INT-FSW and INT-PRW. The highly stable INTs with diameters beyond subnanometer scale can be exploited for potential applications in nanofluidic technologies and for mass transport as bioinspired nanochannels.

Pre-analytical sample handling standardization for reliable measurement of metabolites and lipids in LC-MS-based clinical research.

The emerging disciplines of lipidomics and metabolomics show great potential for the discovery of diagnostic biomarkers, but appropriate pre-analytical sample-handling procedures are critical because several analytes are prone to ex vivo distortions during sample collection. To test how the intermediate storage temperature and storage period of plasma samples from K3EDTA whole-blood collection tubes affect analyte concentrations, we assessed samples from non-fasting healthy volunteers (n = 9) for a broad spectrum of metabolites, including lipids and lipid mediators, using a well-established LC-MS-based platform. We used a fold change-based approach as a relative measure of analyte stability to evaluate 489 analytes, employing a combination of targeted LC-MS/MS and LC-HRMS screening. The concentrations of many analytes were found to be reliable, often justifying less strict sample handling; however, certain analytes were unstable, supporting the need for meticulous processing. We make four data-driven recommendations for sample-handling protocols with varying degrees of stringency, based on the maximum number of analytes and the feasibility of routine clinical implementation. These protocols also enable the simple evaluation of biomarker candidates based on their analyte-specific vulnerability to ex vivo distortions. In summary, pre-analytical sample handling has a major effect on the suitability of certain metabolites as biomarkers, including several lipids and lipid mediators. Our sample-handling recommendations will increase the reliability and quality of samples when such metabolites are necessary for routine clinical diagnosis.

Genome-wide association mapping for root traits associated with frost tolerance in faba beans using KASP-SNP markers.

Frost is an abiotic stress factor that threatens plant development and crop productivity not only in cold regions but also in temperate zones. Roots play an important role in plant growth during frost stress. Therefore, variation in root characteristics could be studied to improve frost tolerance in winter faba bean. The present study aimed to identify the genomic regions that control frost tolerance in a winter faba bean population by focusing on root-related traits. A set of 185 genotypes were tested for frost tolerance under artificial frost growth conditions at -16°C, -18°C, and -19°C in a growth chamber. Frost stress reduced the root-related parameters in all genotypes, with a wide variation among genotypes. A genome-wide association study identified nine novel single-nucleotide polymorphisms that are associated with the root-related traits. The most frost-tolerant genotypes were identified; two genotypes, S_028 and S_220, exhibited remarkable performance under frost stress. Moreover, they harbored all four of the alleles favorable for frost tolerance. Remarkably, two markers showed genetic pleiotropic effects with positive allele effects on root fresh matter and root dry matter. Thus, both genotypes can be implemented in a breeding program to provide the alleles for healthier roots under frost conditions to develop more frost-tolerant varieties, and the two markers can be used to screen large collections to select for frost tolerance. These results may provide novel insights for improving frost tolerance in faba beans and in other legume crops.

Melatonin-mediated temperature stress tolerance in plants.

Global climate changes cause extreme temperatures and a significant reduction in crop production, leading to food insecurity worldwide. Temperature extremes (including both heat and cold stresses) is one of the most limiting factors in plant growth and development and severely affect plant physiology, biochemical, and molecular processes. Biostimulants like melatonin (MET) have a multifunctional role that acts as a "defense molecule" to safeguard plants against the noxious effects of temperature stress. MET treatment improves plant growth and temperature tolerance by improving several defense mechanisms. Current research also suggests that MET interacts with other molecules, like phytohormones and gaseous molecules, which greatly supports plant adaptation to temperature stress. Genetic engineering via overexpression or CRISPR/Cas system of MET biosynthetic genes uplifts the MET levels in transgenic plants and enhances temperature stress tolerance. This review highlights the critical role of MET in plant production and tolerance against temperature stress. We have documented how MET interacts with other molecules to alleviate temperature stress. MET-mediated molecular breeding would be great potential in helping the adverse effects of temperature stress by creating transgenic plants.

Acidic electrolyzed water treatment retards softening and retains cell wall polysaccharides in pulp of postharvest fresh longans and its possible mechanism.

Effects of acidic electrolyzed water (AEW) treatment (pH = 2.5, ACC = 80 mg L-1, 10 min) on pulp firmness, amounts of CWM and CWP, activities and expression of relevant genes of CWDEs in pulp of Fuyan longan during storage at 25 °C were evaluated. Compared to control samples, during storage, AEW-treated fruit retained a higher pulp firmness, prevented WSP formation, reduced the degradation of CSP, cellulose and hemicellulose, and lowered CWDEs activities and their corresponding gene expression. When stored for 5 d, pulp firmness (113.6 g mm-1), CWM (13.9 g kg-1), and CSP (1.4 g kg-1) in AEW-treated fruit displayed the clearly higher contents than those in control samples. These data suggest that AEW treatment can slow down the pulp softening and retain higher pulp CWP levels in postharvest fresh longans, which was because AEW lowered activities of CWDEs and its gene expression levels, and maintained the cell wall structure's integrity.

Effect of Freezing Process on the Microstructure of Gelatin Methacryloyl Hydrogels.

Gelatin methacryloyl (GelMA) hydrogels have aroused considerable interests in the field of tissue engineering due to tunable physical properties and cell response parameters. A number of works have studied the impact of GelMA concentration, photo-initiator concentration, methacrylic anhydride (MA) concentration, cooling rate and temperature gradient on GelMA hydrogel generation, but little attention has been paid to the effect of the freezing temperatures and freezing time of GelMA prepolymer solution during preparation. In this study, GelMA hydrogels were synthesized with different freezing temperatures and time. It was found that the lower freezing temperatures and longer freezing time caused smaller pore sizes that realized higher cell viability and proliferation of MC3T3-E1 cells. The results showed that tunable microstructure of GelMA could be achieved by regulating the freezing conditions of GelMA, which provided a broad prospect for the applications of GelMA hydrogels in tissue engineering.