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Glaucoma is a leading cause of irreversible blindness worldwide and is characterized by progressive retinal ganglion cell (RGC) degeneration and vision loss. Since irreversible neurodegeneration occurs before diagnosable, early diagnosis and effective neuroprotection are critical for glaucoma management. Small extracellular vesicles (sEVs) are demonstrated to be potential novel biomarkers and therapeutics for a variety of diseases. In this study, it is found that intravitreal injection of circulating plasma‐derived sEVs (PDEV) from glaucoma patients ameliorated retinal degeneration in chronic ocular hypertension (COH) mice. Moreover, it is found that PDEV‐miR‐29s are significantly upregulated in glaucoma patients and are associated with visual field defects in progressed glaucoma. Subsequently, in vivo and in vitro experiments are conducted to investigate the possible function of miR‐29s in RGC pathophysiology. It is showed that the overexpression of miR‐29b‐3p effectively prevents RGC degeneration in COH mice and promotes the neuronal differentiation of human induced pluripotent stem cells (hiPSCs). Interestingly, engineered sEVs with sufficient miR‐29b‐3p delivery exhibit more effective RGC protection and neuronal differentiation efficiency. Thus, elevated PDEV‐miR‐29s may imply systemic regulation to prevent RGC degeneration in glaucoma patients. This study provides new insights into PDEV‐based glaucoma diagnosis and therapeutic strategies for neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Large aldehydes are widespread in the atmosphere and their oxidation leads to secondary organic aerosols. The current understanding of their chemical transformation processes is limited to hydroxyl radical (OH) oxidation during daytime and nitrate radical (NO3) oxidation during nighttime. Here, we report quantitative kinetics calculations of the reactions of hexanal (C5H11CHO), pentanal (C4H9CHO), and butanal (C3H7CHO) with hydroperoxyl radical (HO2) at atmospheric temperatures and pressures. We find that neither tunneling nor multistructural torsion anharmonicity should be neglected in computing these rate constants; strong anharmonicity at the transition states is also important. We find rate constants for the three reactions in the range 3.2–7.7 × 10−14 cm3 molecule−1 s−1 at 298 K and 1 atm, showing that the HO2 reactions can be competitive with OH and NO3 oxidation under some conditions relevant to the atmosphere. Our findings reveal that HO2-initiated oxidation of large aldehydes may be responsible for the formation of highly oxygenated molecules via autoxidation. We augment the theoretic studies with laboratory flow-tube experiments using an iodide-adduct time-of-flight chemical ionization mass spectrometer to confirm the theoretical predictions of peroxy radicals and the autoxidation pathway. We find that the adduct from HO2 + C5H11CHO undergoes a fast unimolecular 1,7-hydrogen shift with a rate constant of 0.45 s−1. We suggest that the HO2 reactions make significant contributions to the sink of aldehydes. [ABSTRACT FROM AUTHOR]

The influences of cooling rate on the phase constitution, microstructural length scale, and microhardness of directionally solidified Galvalume (Zn-55Al-1.6Si) alloy were investigated by directional solidification experiments at different withdrawal speeds (5, 10, 20, 50, 100, 200, and 400 µm·s-1). The results show that the microstructure of directionally solidified Galvalume alloys is composed of primary Al dendrites, Si-rich phase and (Zn-Al-Si) ternary eutectics at the withdrawal speed ranging from 5 to 400 µm·s-1. As the withdrawal speed increases, the segregation of Si element intensifies, resulting in an increase in the area fraction of the Si-rich phase. In addition, the primary Al dendrites show significant refinement with an increase in the withdrawal speed. The relationship between the primary dendrite arm spacing (λ1) and the thermal parameters of solidification is obtained: λ1=127.3V-0.31. Moreover, as the withdrawal speed increases from 5 to 400 µm·s-1, the microhardness of the alloy increases from 90 HV to 151 HV. This is a combined effect of grain refinement and second-phase strengthening. [ABSTRACT FROM AUTHOR]