In the present study, we investigated the degradation kinetics and transformation pathways of two 5halogenosalicylic acids (5XSAs), namely, 5-chlorosalicylic acid (5ClSA) and 5-bromosalicylic acid (5BrSA) by sulfate radical (SO 4 -) in a thermo-activated persulfate system. The reaction pathways and mechanisms were proposed based on laser flash photolysis (LFP) techniques, HPLC-HRMS and molecular orbital calculations. Our results revealed that efficient removal of 5XSAs could be achieved by thermo-activated persulfate, and phenoxyl radicals were found to play key roles in the primary oxidation pathways. The subsequent transformation of phenoxyl radicals included hydroxylation and coupling processes. The resulting coupling products could undergo secondary reactions with sulfate radical, including dehalogenation, decarboxylation and hydroxylation. Hydroxylated products were in turn oxidized by SO 4 -, leading to the ring opening and the formation of a series of small molecular carbonyl byproducts. These processes could be responsible for the mineralization and the release of Bror Cl-. In addition, the degradation rate constants of 5XSAs increased appreciably with increasing temperature, and higher efficiency of oxidation was observed around neutral initial pH. Moreover, degradation kinetics were found to be hardly affected by dissolved oxygen (DO), showing the possibility of applying SR-AOPs under environmental realistic conditions, not only for surface waters, but also for oxygen-deficient underground waters. The present work could increase our understanding of the reactivity and pathways of halogen phenols widely present in natural waters.

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Contamination of the environment by toxic pesticides has become of great concern in agricultural countries. Chlorpyrifos (CP) is among the pesticides most commonly detected in the environment owing to its wide agricultural applications. The aim of this study was to compare potential changes in the toxicity of CP after irradiation. To this end, photolysis of CP was conducted under simulated sunlight, and neurotoxicity assessment was carried out at CP of 20 and 50 μg L–1 and its corresponding irradiated mixture solutions which contain a mixture of identified intermediates using the nematode, Caenorhabditis elegans as a model organism. Photodegradation of 20 μg L–1 CP for 1 h produced no obvious reduction of physiological damage, and more serious effects on animal movement were detected after exposure of the animals to a solution of 50 μg L–1 for 1 h irradiation compared with unirradiated solution. GABAergic and cholinergic neurons were selectively vulnerable to CP exposure, and maximal neuropathological alterations were observed after 1 h irradiation of the CP solutions in coherence with the behavioral impairment. The generation of photoproducts was considered to be responsible for the enhanced disturbance on those biological processes. This work provided useful information on the toxicological assessments of chemicals that were produced during the environmental transformation of pesticides.

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As major regulators on bone formation/resorption in response to mechanical stimuli, osteocytes have shown great promise for restoring bone injury. However, due to the unmanageable and unabiding cell functions in unloading or diseased environments, the efficacy of osteogenic induction by osteocytes has been enormously limited. Herein, a facile method of oscillating fluid flow (OFF) loading for cell culture is reported, which enables osteocytes to initiate only osteogenesis and not the osteolysis process. After OFF loading, multiple and sufficient soluble mediators are produced in osteocytes, and the collected osteocyte lysates invariably induce robust osteoblastic differentiation and proliferation while restraining osteoclast generation and activity under unloading or pathological conditions. Mechanistic studies confirm that elevated glycolysis and activation of the ERK1/2 and Wnt/𝜷-catenin pathways are the major contributors to the initiation of osteoinduction functions induced by osteocytes. Moreover, an osteocyte lysate-based hydrogel is designed to establish a stockpile of "active osteocytes" to sustainably deliver bioactive proteins, resulting in accelerated healing through regulation of endogenous osteoblast/osteoclast homeostasis.