Asymmetric Hydrophosphonylation of Imines to Construct Highly Stable Covalent Organic Frameworks with Efficient Intrinsic Proton Conductivity.

Imine-linked covalent organic frameworks (COFs) have received widespread attention because of their structure features such as high crystallinity and tunable pores. However, the intrinsic reversibility of the imine bond leads to the poor stability of imine-linked COFs under strong acid conditions. Also, their thermal stability is significantly lower than that of many other COFs. Herein, we report for the first time that the reversible imine bonds in the skeleton of COFs can be locked through the asymmetric hydrophosphonylation reaction of phosphite. The functionalized COFs not only retain the crystallinity and porous structure but also exhibit evidently improved chemical and thermal stabilities. In addition, the phosphorous acid groups generated by acidic hydrolysis attached to the skeleton endow the COFs with good intrinsic proton conductivity. Due to the diversity of phosphite derivatives and imine-linked COFs, this work may provide an avenue for extending the COF structures and functions through the asymmetric hydrophosphonylation reaction.

Characterization of fibrosis changes in chronic hepatitis C patients after virological cure: A systematic review with meta-analysis.

BACKGROUND AND AIM: Virological cure becomes available for most patients with chronic hepatitis C (CHC), but residual fibrosis can be an independent risk factor for liver-related complications. We aimed to characterize fibrosis change in CHC patients achieved virological cure. METHODS: We did a systematic literature search for studies that had pre and post-treatment evaluations of histologic fibrosis in CHC patients with sustained virological response (SVR). We identified the association of SVR with the incidence, extent, and velocity of fibrosis change. RESULTS: Overall, 3243 patients were included. Interferon-based regimens were used for all the patients, achieving a median SVR prevalence of 36.2%. Biopsy interval ranged from 1 to 10 years. Mean baseline fibrosis score (METAVIR) was 2.3 points. Compared with non-SVR patients, SVR patients could have higher incidence of fibrosis regression (35.1% vs 17.0%; OR: 3.3; P < 0.001), regardless of baseline fibrosis severity, way of biopsy evaluation, treatment regimen, or study design, and could have more extent of reduction (-0.31 points vs -0.00 points; P = 0.004). Baseline advanced fibrosis (F > 2) was associated with more rapid regression in both SVR and non-SVR patients (P < 0.05 for both). SVR patients could have lower incidence of fibrosis progression and maintenance than non-SVR patients by 4.8% versus 23.1% (OR: 0.20; P = 0.008) and 42.9% versus 55.2% (OR: 0.53; P < 0.001), respectively. CONCLUSIONS: There could be a favorable characteristic of fibrosis regression in SVR patients. However, residential fibrosis may remain an issue because of a non-ignorable prevalence of fibrosis maintenance among these patients.

[Effects of Polystyrene Microplastics Combined with Cadmium Contamination on Soil Physicochemical Properties and Physiological Ecology of Lactuca sativa].

Contaminants such as microplastics (MPs) and heavy metals are commonly found in soils, both of which are extremely difficult to degrade and can easily form compound contamination, altering the physicochemical properties of the soil and thus potentially changing the growth and physiological and ecological characteristics of plants. In order to study the effects of the combined contamination of soil MPs and heavy metals on soil properties and plant growth, polystyrene microplastics (PS-MPs) with a particle size of 3 µm and the heavy metal cadmium were selected in the study. The changes in the physicochemical properties of soil and their effects on lettuce (Lactuca sativa) seed germination and seedling growth were studied at various exposure concentrations of PS-MPs (0, 10, 50, 100, 200, and 400 mg·kg-1) and combined with different Cd contamination concentrations (0, 1.2, and 6.0 mg·kg-1), respectively. The results showed that soil organic matter (SOM), available phosphorus (AP), alkali-hydrolysable nitrogen (AHN), and available kalium (AK) showed significant decreases as the intensity of PS-MPs combined with Cd contamination increased. Simultaneously, PS-MPs combined with Cd contamination also significantly reduced the germination rate of lettuce seeds, but low concentrations of PS-MPs slowed down the effect of Cd (6.0 mg·kg-1) contamination on lettuce seeds, and high concentrations of PS-MPs enhanced the effect of Cd (6.0 mg·kg-1). The fresh weight, dry weight, and plant height of lettuce seedlings showed an increasing and then decreasing trend with increasing exposure to PS-MPs. Chlorophyll content, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) showed a decreasing trend, whereas malondialdehyde (MDA) content showed an overall increasing trend under different Cd concentrations. The main physicochemical indicators of the soil were negatively correlated with MDA of lettuce seedlings, whereas other indicators of the seedlings were positively correlated. The combined contamination of PS-MPs and Cd could affect the germination of plant seeds and the physiological and ecological characteristics of seedlings by changing the physicochemical properties of the soil. Both exposure to single PS-MPs contaminants and the combination of PS-MPs with Cd inhibited the germination of lettuce seeds and affected the physiological activities of their seedlings, and the inhibition was significantly increased with increasing exposure. Low exposure to PS-MPs or the combination of PS-MPs with Cd contamination exhibited a promotive effect on lettuce seedling growth. High exposure to PS-MPs combined with Cd contamination exhibited significant ecological effects on lettuce seedlings, and high exposure to PS-MPs exacerbated the ecotoxicological effects of Cd contaminants on lettuce seedlings, and PS-MPs and Cd exhibited synergistic effects. The results can provide some reference for assessing the ecological effects of MPs and heavy metal pollution in soil-plant systems.