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Background The longitudinal antigen-specific immunity in COVID-19 convalescents is crucial for long-term protection upon individual re-exposure to SARS-CoV-2, and even more pivotal for ultimately achieving population-level immunity. To better understand the features of immune memory in individuals with different disease severities at one year post-disease onset we conducted this cohort study. Methods We conducted a systematic antigen-specific immune evaluation in 101 COVID-19 convalescents, who had asymptomatic, mild, moderate, or severe disease, through two visits at months 6 and 12 post-disease onset. The SARS-CoV-2-specific antibodies, comprising NAb, IgG, and IgM, were assessed by mutually corroborated assays, i.e. neutralization, enzyme-linked immunosorbent assay (ELISA), and microparticle chemiluminescence immunoassay (MCLIA). Meanwhile, the T-cell memory against SARS-CoV-2 spike, membrane and nucleocapsid proteins was tested through enzyme-linked immunospot assay (ELISpot), intracellular cytokine staining (ICS), and tetramer staining-based flow cytometry, respectively. Results SARS-CoV-2-specific IgG antibodies, and also NAb can persist among over 95% COVID-19 convalescents from 6 months to 12 months after disease onset. At least 19/71 (26%) of COVID-19 convalescents (double positive in ELISA and MCLIA) had detectable circulating IgM antibody against SARS-CoV-2 at 12m post-disease onset. Notably, the percentages of convalescents with positive SARS-CoV-2-specific T-cell responses (at least one of the SARS-CoV-2 antigen S1, S2, M and N protein) were 71/76 (93%) and 67/73 (92%) at 6m and 12m, respectively. Furthermore, both antibody and T-cell memory levels of the convalescents were positively associated with their disease severity. Conclusions SARS-CoV-2-specific cellular and humoral immunities are durable at least until one year after disease onset.

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We overcome the fundamental dilemma in achieving hard materials with self-healing capability by integrating an epidermis-like hierarchical stratified structure with attractive mechanical and barrier properties of graphene oxide and show that such biomimetic design enables a smart hierarchical coating system with a synergetic healing effect and a record-high stiffness (31.4 ± 1.8 GPa)/hardness (2.27 ± 0.09 GPa) among all self-healable polymeric films even comparable to that of tooth enamel. A quasi-linear layer-by-layer (LBL) film with constituent graphene oxide is deposited on top of an exponential LBL counterpart as a protective hard layer, forming a hierarchical stratified assembly mimicking the structure of epidermis. The hybrid multilayers can achieve a complete restoration after scratching thanks to the mutual benefit: The soft underneath cushion can provide additional polymers to assist the recovery of the outer hard layer, which in turn can be a sealing barrier promoting the self-healing of the soft layer during stimulated polymer diffusion. The presenting hybridization mode of LBL assembly represents a promising tool for integrating seemingly contradictory properties in artificial materials with potential performances surpassing those in nature.

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The interactions between the gut microbiome and metabolome play an important role in human health and diseases. Current studies mainly apply statistical correlation analysis between the gut microbiome and all the identified metabolites to explore their relationship. However, it remains challenging to identify the specific metabolic functions of microbes without in vitro culture experiments for validation. Discriminating the microbial metabolites from others (e.g., host, food, or environment) and exploring their metabolic functions and correlations with microbiome specifically may improve the efficiency and accuracy of biomarker discovery. So far, there have been no such bioinformatics tools available. Herein, we developed MetOrigin, an interactive web server that discriminates metabolites originating from the microbiome, performs the origin‐based metabolic pathway enrichment analysis, and integrates the statistical correlations and biological relationships in the database using Sankey network visualization. MetOrigin not only enables the quick identification of microbial metabolites and their metabolic functions but also facilitates the discovery of specific bacterial species that are closely associated with metabolites statistically and biologically. MetOrigin is freely available at http://metorigin.met-bioinformatics.cn/.

The present study reports on the development of a method using ultrasound-assisted extraction (UAE) during the purification of taurine from Porphyra yezoensis. The Box-Behnken design, which is a widely used form of response surface methodology, was used to investigate the effects of parameters on the UAE process. Three independent variables of taurine purification using UAE were studied including: extraction time, temperature, and ultrasonic power. The results showed that the highest taurine yield of 13.0mg/g was obtained with an extraction time of 38.3 min, the use of 300.0 W ultrasonic power, and an extraction temperature of 40.5°C. A comparative study of taurine extraction was also conducted using either ultrasonication or mechanical agitation. The results indicated that the ultrasonic process required 9 times less time at 40°C to obtain taurine with a similar yield as compared to the conventional extraction method. Therefore, UAE can used as an alternative to the conventional extraction method used during the recovery of taurine from P. yezoensis. The UAE method has several advantages, including that it uses lower extraction temperatures and has a shorter extraction time. The taurine present in the extract supernatant was efficiently separated and purified using a combination of 732 cation exchange chromatography and crystallization. The yield of purified taurine using this process was 1.1%. The structure of the purified taurine was confirmed by FTIR, MS, and NMR. Our findings suggest that P. yezoensis can be used as a taurine-rich food or food material.

Two-line ferrihydrite (Fh), ubiquitous in soils, groundwater, and aquatic sediments, may serve as an important sink for sequestering trace metals, metalloids, and organic matter via adsorption/coprecipitation due to its high surface area and reactivity. Although considerable attention has been paid to the transformation process of this thermodynamically metastable solid, little is known about the transformation products, the crystallization rates, or the transformation routes of two-line Fh in sulfate- and calcium-rich environments. This work systematically investigates the transformation of 2-line ferrihydrite produced by using different neutralization reagents (CaO vs NaOH) at different pHs (4 and 8), temperatures (25 °C, 40 °C, and 80 °C), and media (sulfate vs nitrate). X-ray diffraction, Raman, Fourier transform infrared spectroscopy, and chemical extraction were employed to characterize the transformed solids as well as the crystallization rate of 2-line Fh. The results show that the crystallization products in nitrate media include hematite (major) and goethite (minor) under acidic conditions (pH 4) and only hematite under alkaline conditions (pH 8) and are independent of the neutralization reagent used. By contrast, in sulfate media, goethite is the dominant product under slightly acidic conditions (pH 4) with 6-line ferrihydrite as the intermediate product, whereas under slightly alkaline conditions the formation of hematite is favored. Chemical extraction results indicate that the transformation process of those CaO-neutralized solids precipitated at pH 8 is intensely retarded by calcium ion. The results suggest that neutralization reagents (calcium ion), as well as the reaction media (sulfate ion), play an important role in the 2-line ferrihydrite crystallization process.