Construction of Poly(butylene succinate)-Grafted Graphene Bionanocomposites: Intercalation Structure, Synergistic Thermal–Oxidative Stabilization Effect, and Hydrolytic Behavior

Poly(butylene succinate) (PBS) is considered a promising biodegradable material, whereas poor mechanical/thermal properties and low hydrolysis rate restrict its further application. Herein, 1,4-butanediol (BDO) was chemically grafted onto the graphene oxide (GO) surface by the coupling effect of diisocyanate [e.g., 4,4′-diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), and hexamethylene diisocyanate (HDI)], and the corresponding bionanocomposites were prepared via in situ polymerization. By comparison, MDI has higher reactivity with GO and BDO due to induction and the spatial steric effect, and a strong interfacial covalent interaction of GO–MDI–PBS was formed. Therefore, more PBS molecules were grafted onto GO and intercalated into nanosheet layers to achieve a uniform dispersion in the matrix. GO–MDI–PBS-0.5 wt % exhibited the maximum tensile strength (39.96 MPa), elongation at break (458.48%), and notched impact strength (9.80 kJ/m2), nearly 21.27, 44.58, and 127.91% increase than those of neat PBS, respectively, achieving simultaneous improvement in mechanical strength and toughness. Besides, effective intercalation enlarged the contact area with free radicals, resulting in extraordinary radical scavenging ability of GO, and the excellent oxygen barrier property of the composite was enhanced because the uniform dispersion of GO sheets caused a more tortuous diffusion pathway for oxygen, which endowed GO–MDI–PBS with remarkable thermal–oxidative stability. Furthermore, GO–MDI–PBS exhibited the improvement of crystallization rate, surface hydrophilicity, and water vapor barrier properties, effectively promoting hydrolysis

Additional file 2: of First identification and multilocus genotyping of Giardia duodenalis in pet chipmunks (Eutamias asiaticus) in Sichuan Province, southwestern China

Figure S1. Phylogenetic relationships of Giardia duodenalis for the bg, tpi, and gdh loci (a, bg; b, tpi; c, gdh). The relationships between G. duodenalis genotypes identified in this study and other known genotypes deposited in GenBank were inferred by a neighbor-joining analysis of three genetic loci using the Kimura 2-parameter model. Bootstrap values greater than 50% from 1000 replicates are shown. Sequences obtained in this study are marked with a triangle. (TIFF 529 kb

Multi-locus genotypes of <i>Enterocytozoon bieneusi</i> in captive Asiatic black bears in southwestern China: High genetic diversity, broad host range, and zoonotic potential

<div><p><i>Enterocytozoon bieneusi</i> is an obligate eukaryotic intracellular parasite that infects a wide variety of vertebrate and invertebrate hosts. Although considerable research has been conducted on this organism, relatively little information is available on the occurrence of <i>E</i>. <i>bieneusi</i> in captive Asiatic black bears. The present study was performed to determine the prevalence, genetic diversity, and zoonotic potential of <i>E</i>. <i>bieneusi</i> in captive Asiatic black bears in zoos in southwestern China. Fecal specimens from Asiatic black bears in four zoos, located in four different cities, were collected and analyzed for the prevalence of <i>E</i>. <i>bieneusi</i>. The average prevalence of <i>E</i>. <i>bieneusi</i> was 27.4% (29/106), with the highest prevalence in Guiyang Zoo (36.4%, 16/44). Altogether, five genotypes of <i>E</i>. <i>bieneusi</i> were identified among the 29 <i>E</i>. <i>bieneusi</i>-positive samples, including three known genotypes (CHB1, SC02, and horse2) and two novel genotypes named ABB1 and ABB2. Multi-locus sequence typing using three microsatellites (MS1, MS3, and MS7) and one minisatellite (MS4) revealed V, III, V, and IV genotypes at these four loci, respectively. Phylogenetic analysis showed that the genotypes SC02 and ABB2 were clustered into group 1 of zoonotic potential, the genotypes CHB1 and ABB1 were clustered into a new group, and the genotype horse2 was clustered into group 6 of unclear zoonotic potential. In conclusion, this study identified two novel <i>E</i>. <i>bieneusi</i> genotypes in captive Asiatic black bears, and used microsatellite and minisatellite markers to reveal <i>E</i>. <i>bieneusi</i> genetic diversity. Moreover, our findings show that genotypes SC02 (identified in humans) and ABB2 belong to group 1 with zoonotic potential, suggesting the risk of transmission of <i>E</i>. <i>bieneusi</i> from Asiatic black bears to humans and other animals.</p></div

Phylogenetic relationship among <i>Enterocytozoon bieneusi</i> groups; the relationship between <i>E</i>. <i>bieneusi</i> genotypes identified in this study and other known genotypes deposited in GenBank was inferred by neighbor-joining analysis of ITS sequences based on genetic distance using the Kimura-2-parameter model.

<p>The numbers on the branches represent percent bootstrapping values from 1,000 replicates, with more than 50% shown in the tree. Each sequence is identified by its accession number, genotype designation, and host origin. Genotypes marked with <i>black triangles</i> and <i>black circles</i> are novel and known genotypes identified in this study, respectively.</p

Prevalence and genotypes of <i>E</i>. <i>bieneusi</i> in Asiatic black bears from zoos in Southwestern China.

<p>Prevalence and genotypes of <i>E</i>. <i>bieneusi</i> in Asiatic black bears from zoos in Southwestern China.</p

Multi-locus sequence typing of <i>Enterocytozoon bieneusi</i> in Asiatic black bears in Southwestern China.

<p>Multi-locus sequence typing of <i>Enterocytozoon bieneusi</i> in Asiatic black bears in Southwestern China.</p

Prevalence and distribution of <i>Giardia intestinalis</i> in different regions of the Sichuan province of southwestern China.

<p>Prevalence and distribution of <i>Giardia intestinalis</i> in different regions of the Sichuan province of southwestern China.</p

Assemblages of <i>Giardia intestinalis</i> and the distribution of <i>tpi</i>, <i>bg</i>, and <i>gdh</i> sequences for each positive racehorse and multilocus characterization.

<p>Assemblages of <i>Giardia intestinalis</i> and the distribution of <i>tpi</i>, <i>bg</i>, and <i>gdh</i> sequences for each positive racehorse and multilocus characterization.</p

Primer sequences and annealing temperatures of the genes used in this study, as well as the fragment lengths of the PCR products.

<p>Primer sequences and annealing temperatures of the genes used in this study, as well as the fragment lengths of the PCR products.</p