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In this study, an epoxy based on eugenol and an anhydride curing agent based on rosin were prepared. Curing of the eugenol epoxy with a commercial anhydride curing agent and with the rosin-derived anhydride curing agent was studied. For comparison, a commercial bisphenol A type epoxy, DER353, was also selected in the curing study. The syntheses of the eugenol epoxy and rosin anhydride were investigated and the chemical structures of the products and intermediates were characterized using 1 H NMR and Fourier transform infrared spectroscopies. Non-isothermal curing of the eugenol epoxy with hexahydrophthalic anhydride and the rosin-derived maleopimaric acid was studied using differential scanning calorimetry. Thermomechanical properties and thermal stability of the cured epoxy resins were evaluated using dynamic mechanical analysis and thermogravimetric analysis, respectively. Addition of 2-ethyl-4-methylimidazole as catalyst greatly decreased the curing temperature and promoted the completion of cure reactions. The results suggest that the eugenol epoxy and the bisphenol A type epoxy have similar reactivity, dynamic mechanical properties and thermal stability.

Porcine enteric alphacoronavirus (PEAV) was first discovered in China in February 2017, and the origin and virulence of this novel porcine coronavirus were not fully characterized. Here, we isolated a strain of PEAV, named GDS04 that is identified by immunofluorescence and typical crown-shaped particles observed with electron microscopy. Genomic analysis reveals that PEAV GDS04 shares a close relationship with SADS-CoV and SeACoV. Furthermore, newborn piglets orally challenged with PEAV GDS04 developed typical clinical symptoms as watery diarrhoea in neonatal piglets. Viral RNA was detected in faeces and various tissues of the infected piglets. Moreover, macroscopic and microscopic lesions in whole intestinal tract were observed, and viral antigen could be detected in the small intestines by immunohistochemical staining and electron microscopy. Importantly, the mortality rate of inoculated-newborn piglets was 100% and half of the cohabiting piglets died. Collectively, we demonstrate that PEAV is highly pathogenic in newborn piglets.

The self-healable polymer hydrogel along with reversible temperature responsiveness was prepared through self-catalyzed dynamic acylhydrazone formation and exchange without any additional stimulus or catalyst. The hydrogel was prepared from a copolymer of N-isopropylacrylamide and acylhydrazine P(NIPAM-co-AH) cross-linked by PEO dialdehyde. Besides self-healed under catalysis of acid and aniline, the hydrogel can also self-heal activated by excess of acylhydrazine groups. Without interference of catalyst during the hydrogel formation and self-healing, this kind of hydrogel prepared from biocompatible polymers can be used in more areas including biotechnology and be more persistent. The hydrogel with a large part of the PNIPAM segment also showed temperature responsiveness around body temperature influenced by the variation in group ratio. This self-healable hydrogel has great potential application in areas related to bioscience and biotechnology.

In this study, Kraft lignin was partially depolymerized through base catalyzed depolymerization (BCD) in supercritical methanol to increase its solubility in organic solvents. The resulting partially depolymerized lignin (PDL) was then converted to lignin-based polycarboxylic acid (LPCA) by reacting with succinic anhydride. The hydroxyl value of PDL and acid value of LPCA were determined using 31 P NMR. LPCA was used as a curing agent to cure a commercial epoxy (DER353). Because LPCA was a soft solid, glycerol tris(succinate monoester) (GTA) which was liquid at room temperature was also synthesized and used as cocuring agent and a diluent for LPCA. Dynamic mechanical properties and thermal stability of the cured epoxy resins were examined using dynamic mechanical analysis and thermogravimetric analysis, respectively. Results showed that curing of DER353 with the LPCA resulted in an epoxy resin with a moderate glass transition temperature (T g ) and a storage modulus comparable to the resin cured with the commercial hexahydrophthalic anhydride (HHPA). However, thermal and thermal mechanical properties of the cured resins could be greatly regulated by using GTA or HHPA as a cocuring agent.

Background: The emergence and spread of HIV-1 drug resistance may compromise HIV control globally. In response to HIV/AIDS epidemic, China launched national HIV/AIDS treatment program in 2003, and started to accumulate drug resistance data since 2001. In this study we aimed to assess the level, trend and distribution of HIV-1 drug resistance during a period of 17 years from 2001 to 2017, and to characterize crucial drug resistance mutations. Methods: We systematically reviewed 4737 studies published between January 1, 2001 and March 31, 2019 in PubMed, Embase, China National Knowledge Infrastructure (CNKI), WanFang Database, Web of Science, conference abstracts from the Chinese Medical Association and the Chinese AIDS Academic Conferences, and selected 170 studies that met our study criteria. To assess the prevalence of drug resistance in whole country or a local region, we performed pooled analyses of raw data. The transformed proportions were pooled using the inverse variance fixed effects methods or the DerSimonian-Laired random effects methods. The temporal trend of transmitted drug resistance (TDR) was determined using generalized additive model implemented in the Mgcv version 1.8 package. HIV-1 genotypic resistance was analyzed using the Stanford HIVdb algorithm. Findings: We assembled 218 datasets from 170 selected studies (129 in Chinese and 41 in English), covering 21,451 ART-naïve and 30,475 ART-treated individuals with HIV-1 infection. The pooled prevalence of TDR was 3.0% (95%CI: 2.8À3.2), including 0.7% (95%CI: 0.4À1.0), 1.4% (95%CI: 1.3À1.6) and 0.5% (95%CI: 0.4À0.6) for nucleoside reverse transcriptase inhibitor (NRTI), non-NRTI (NNRTI) and protease inhibitor (PI) resistance, respectively. The acquired drug resistance (ADR) prevalence was 44.7% (95%CI: 39.3À50.2), including 31.4% (95%CI: 28.2À34.6), 39.5% (95%CI: 35.6À43.5) and 1.0% (95%CI: 0.8À1.2) for NRTI, NNRTI and PI resistance, respectively. TDR and ADR prevalence had characteristic regional patterns. The worst prevalence of drug resistance occurred in Central China, and higher ADR prevalence occurred in South China than North China. TDR in whole country has risen since 2012, and this rise was driven mainly by NNRTI resistance. One NRTI-associated (M184V/I) and three NNRTI-associated (K103N/S, Y181C/I and G190A/S) mutations had high percentages in ART-naïve and ARTtreated individuals, and these mutations conferred high-level resistance to 3TC, EFV and/or NVP. Interpretation: These findings suggest that the current available first-line ART regimens containing 3TC and/ or EFV or NVP need to be revised. In addition, scale-up of multiple viral load measurements per year and drug resistance testing prior to ART initiation are recommended. Furthermore, implementation of pre-treatment education and counseling to improve patient adherence to ART is encouraged.

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has caused a global pandemics. To facilitate the detection of SARS-CoV-2 infection, various RT-LAMP assays using 19 sets of primers had been developed, but never been compared. We performed comparative evaluation of the 19 sets of primers using 4 RNA standards and 29 clinical samples from COVID-19 patients. Six of 15 sets of primers were firstly identified to have faster amplification when tested with four RNA standards, and were further subjected to parallel comparison with the remaining four primer sets using 29 clinical samples. Among these 10 primer sets, Set-4 had the highest positive detection rate of SARS-CoV-2 (82.8%), followed by Set-10, Set-11, and Set-13 and Set-17 (75.9%). Set-14 showed the fastest amplification speed (Tt value < 8.5 min), followed by Set-17 (Tt value < 12.5 min). Based on the overall detection performance, Set-4, Set-10, Set-11, Set-13, Set-14 and Set-17 that target Nsp3, S, S, E, N and N gene regions of SARS-CoV-2, respectively, were determined to be better than the other primer sets. Two RT-LAMP assays with the Set-4 primers in combination with any one of four other primer sets (Set-14, Set-10, Set-11, and Set-13) were recommended to be used in the COVID-19 surveillance.

We report the bulk self-assembly of diblock copolymer poly(tert-butyl acrylate)-blockpoly(glycidyl methacrylate) (PtBA-b-PGMA) with the PGMA that bears many epoxy groups as a crosslinkable segment and the PtBA as a hydrolyzable segment. The PtBA-b-PGMA block copolymers of a different composition were synthesized by two-step atom transfer radical polymerization (ATRP). After bulk self-assembly, the morphologies of microphase separation of the block copolymers were studied with smallangle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The results showed that with decrease of volume ratio of the PGMA segments the PtBA-b-PGMA self-assembled into lamellae, cylinders, and spheres with the dispersed PGMA domains. The epoxy groups in the PGMA domains were cross-linked by exposing the microphase-separated films into an atmosphere of either ethylenediamine (EDA) or propargylamine (PA). Then the bulk materials were dispersed into the good solvent of PtBA to generate the polymeric nanoobjects of plates, fibers, and spheres, of which the cross-linked PGMAs were the cores and the PtBAs were the coronas. After hydrolysis of the PtBA segments into the poly(acrylic acid)s (PAAs), the cross-linked nanoobjects could be dispersed in basic water and showed reversible pH responsibility. The pendant alkyne groups in the PA cross-linked nanoobjects were applied to anchor anthracenes by click reaction with 9-(azidomethyl)anthracene (9-AMA).