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Abstract Ice air jet technology is one non-destructive, residue-free and environmentally friendly machining process. It is an efficient method to form ice particles by atomizing water droplets in ultra-low temperature environment. The freezing characteristics of water droplets in cryogenic gas and liquid nitrogen environment are visually analyzed, and the effects of droplet volume, ambient temperature are also studied. The results show that when water droplets freeze in a cryogenic gas environment, four distinct stages are observed, namely pre-cooling stage, recalescence stage, solidification stage, and deep cooling stage. However, when water droplets freeze in liquid nitrogen, the recalescence stage cannot be observed. For a 5 µl water droplet, it takes 68 s for water droplets to freeze into ice particles at − 20.36 °C, while it takes only 1.7 s in liquid nitrogen. During the freezing process, the water droplets form an ice shell outside and freeze inwardly. Ice particles may break up due to differences in solubility and density. With the increase of volume the time spent on pre-cooling stage and freezing stage both increases. For the large latent heat of water phase transformation, the solidification stage time is greatly affected by the volume of water droplets. When the ambient temperature drops from − 10.67 °C to − 24.68 °C, the freezing time of 5 µl water droplets decreases by 45.5%, indicating that the ambient temperature has a great influence on the freezing time. The results of the study can significantly contribute to the development of ice air jet technology.

Remediation of antibiotics by photocatalysis technique has been regarded as a promising route to tackle with the environmental pollution affecting human survival and development. In this work, brookite TiO2 nanorods with different oxygen vacancy have been synthesized through tailoring the volume of ethylene glycol by hydrothermally treatment with NaTiOx-nanoassembly. After constitute and morphology confirmation with different characterizations, their photocatalytic performances are evaluated via ciprofloxacin (CIP) antibiotic degradation experiments. The result shows that the TiO2-0 has the highest photocatalytic efficiency towards CIP degradation, comparing with TiO2-15 and TiO2-30 samples. Although the TiO2-30 has high concentration oxygen vacancy, it exhibits excellent adsorption ability in the dark, rather than CIP degradation rate. The photo/electrochemical tests suggest the photo-generated electron lifetime, charge transfer ability, and the effective active sites on the material's surface are inversely proportional to the concentration of oxygen vacancies. It also concludes that rational fabrication conditions tailoring of the photocatalyst could optimize the corresponding capability in the antibiotic degradation process. In addition, the possible degradation pathway is also proposed based on the high resolution mass spectrometry (HRMS), and the acute toxicity changes in the degradation process are also predicted. [ABSTRACT FROM AUTHOR]

The sporopollenin polymer is a major component of the pollen exine. Fatty acid derivatives synthesized in the tapetum are among the precursors of sporopollenin. Progress has been made to understand sporopollenin metabolism in rice; however, the underlying molecular mechanisms remain elusive. We found that OsTKPR2 and OsTKPR1 share a similar expression pattern, and their coding proteins have a similar subcellular localization and enzyme activities towards reduced tetraketide α-pyrone and hydroxylated tetraketide α-pyrone. Unexpectedly, OsTKPR1 pro : OsTKPR2-eGFP could not rescue the phenotype of ostkpr1-4. Three independent ostkpr2 mutant lines generated by CRISPR/Cas9 displayed reduced male fertility to various extents which were correlated with the severity of gene disruptions. Notably, the anther cuticle, Ubisch bodies, and pollen development were affected in the ostkpr2-1 mutant, where a thinner pollen exine was noticed. OsTKPR1 and OsTKPR2 were integrated into a metabolon including OsACOS12 and OsPKS2, which resulted in a significant increased enzymatic efficiency when both OsTKPR1 and OsTKPR2 were present, indicating the mutual dependence of OsTKPR2 and OsTKPR1 for their full biochemical activities. Thus, our results demonstrated that OsTKPR2 is required for anther and pollen development where an OsTKPR2-containing metabolon is functional during rice sporopollenin synthesis. Furthermore, the cooperation and possible functional divergence between OsTKPR2 and OsTKPR1 is also discussed. [ABSTRACT FROM AUTHOR]