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Formaldehyde-based resins are commonly used in the particleboard industry due to their high bonding strength and excellent water resistance. Nowadays, the healthy and sustainable issues lead to the development of bio-based wood adhesives. In the last past decade, soybeans were the most prominent crop for the production of environmentally friendly adhesive with no formaldehyde in its composition. This review covers the strengths, weaknesses, opportunities and threats of soy-based adhesives as a replacement of conventional resins. Moreover, this work details the different techniques used to improve the performance of soy protein adhesives in order to encourage their use in the wood industry.

Soy protein (SP) is a promising raw material for the development of renewable and environmentally friendly adhesives. This work aims to study the effect of protein denaturation and/or hydrolysis on the rheology of a soy protein isolate (SPI) suspension. Four stages of chemical modification of SPI were evaluated: unmodified (U), denatured (D), partially hydrolyzed (PH) and fully hydrolyzed (H). Fourier-transform infrared spectroscopy (FTIR) and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) confirmed that polypeptides with high molecular weight were fully fragmented into smaller ones. Rheological analysis showed that U behaves as a gel-like material while PH and H act as viscous-like materials. Hydrolysis caused a significant decrease in the viscosity, even for suspensions with high solid content. Furthermore, comparing U and H, the viscosity at high shear strength dropped 65% with an increase of 219% in the solid content. The shear strength of the adhesives can be increased through two strategies: crosslinking with epoxy resin and the addition of different reinforcements. Considering suspension H as reference, the addition of 20% epoxy resin and 5% montmorillonite clay caused an increase in the shear strength of almost 39%. These results could contribute to the development of high solid content SP-based adhesive with desirable rheological properties and zero formaldehyde emission.

Poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT)-based nanocomposites were prepared by melt blending of PLA and PBAT with 5 wt% of unmodified (Cloisite Na) and modified (Cloisite 30B) montmorillonites. X-ray diffraction (XRD) revealed an intercalated structure in both nanocomposites. The extent of the intercalation was higher for nanocomposites based on modified clays (OMMT) with chemical affinity with the polymer matrix. Rheological measurements have shown an increase in viscosity and a better degree of clay dispersion for nanocomposites containing OMMT. Nanocomposites with OMMT showed lower PBAT separated phase particle size and improvements in thermal stability, mechanical properties and water vapor barrier when compared with the neat blend. Finally, our results showed that the organically modified clay has a higher affinity than natural clay with the studied polymer blend.

Abstract To study the effect of host genetics on gut microbiome composition, the MiBioGen consortium curated and analyzed genome-wide genotypes and 16S fecal microbiome data from 18,340 individuals (24 cohorts). Microbial composition showed high variability across cohorts: only 9 out of 410 genera were detected in more than 95% samples. A genome-wide association study (GWAS) of host genetic variation in relation to microbial taxa identified 31 loci affecting microbiome at a genome-wide significant (P<5×10−8) threshold. One locus, the lactase (LCT) gene locus, reached study-wide significance (GWAS signal P=1.28×10−20), and it showed an age-dependent association with Bifidobacterium abundance. Other associations were suggestive (1.95×10−10

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