Damping Properties of Ethylene-Vinyl Acetate Rubber/Polylactic Acid Blends

In this research, ethylene-vinyl acetate rubber (EVM)/polylactic acid (PLA) = 80/20 by weight blend was compounded with silica in a Haake torque rheometer. The effects of hindered phenol (AO-60), super branched polyol, petroleum resin C9, polyvinyl chloride (PVC) and acrylic rubber (ACM) on the damping properties of blends were investigated by dynamic mechanic analyzer (DMA). The results showed that 20 phr super branched polyol significantly increased the damping factor of PLA to widen the effective damping temperature range from 42.1℃to 102.5℃. 15 phr AO-60 and 10 phr petroleum resin C9 both dramatically raised the blend’s damping factor to broaden the effective damping temperature range to 98.0℃ and 102.6℃, respectively. ACM and PVC are compatible with EVM, and both improved the damping properties of EVM/PLA blends.

Optimizing food waste hydrothermal parameters to reduce Maillard reaction and increase volatile fatty acid production

The occurrence of the Maillard reaction and melanoidins formation during the hydrothermal treatment of food waste can reduce the yield of volatile fatty acids(VFA);however, few studies have investigated the adverse effects of the Maillard reaction. This study identified the impact of hydrothermal treatment parameters on hydrolysis and melanoidins formation and optimized the hydrothermal treatment conditions to enhance VFA production by minimizing the impact of the Maillard reaction. A response surface methodology was employed to optimize the hydrothermal treatment parameters and VFA production was evaluated. Results showed that temperature, reaction time, and pH were significant interacting factors with respect to hydrolysis and melanoidins formation while the C/N ratio and moisture content of food waste had little impact. The optimal conditions for hydrothermal treatment(temperature of 132 °C, reaction time of 27 min, and a pH of 5.6) enhanced VFA production by 22.1%. Under optimal hydrothermal treatment conditions, a higher initial C/N ratio further increased VFA production.

Enhanced endosomal escape of dendrigraft poly-L-lysine polymers for the efficient gene therapy of breast cancer

Dendrimer,such as dendrigraft poly-L-lysine(DGL)polymers,with high surface charge density,well-defined structure,and narrow poly-dispersity is often employed as a gene vector,but its transfection efficiency is still partially inhibited due to poor endosomal escape ability.Herein,we used a surface modification strategy to enhance the endosomal escape ability of DGL polymers,and thus improved its gene transfection efficiency.A library of phenylboronic acid(PBA)modified DGL polymers(PBA-DGLs)was designed to screen efficient small interfering RNA(siRNA)vectors.The lead candidate screened from the library shown a capability of inducing nearly 90% gene silencing in MDA-MB-231 cells.The study of the transfection mechanism revealed that PBA modification not only improves siRNA cellular uptake,but,more importantly,endows DGL polymers the ability of endosomal escape.One of the top candidates from polyplexes was further shielded with hyaluronic acid to construct targeted nanoparticles,and the yielding nanoparticles significantly suppressed the tumor growth in a breast cancer model by effective siRNA delivery.This research provides a general and effective strategy to enhance the endosomal escape and transfection efficiency of dendrimer.

Generation and Characterization of a Transgenic Zebrafish Expressing the Reverse Tetracycline Transactivator

Conditional expression of a target gene during zebrafish development is a powerful approach to elucidate gene functions. The tetracycline-controlled systems have been successfully used in the modulation of gene expression in mammalian cells, but few lines of zebrafish carrying these systems are currently available. In this study, we had generated a stable transgenic zebrafish line that ubiquitously expressed the second-generation of reverse Tet transactivator （rtTA-M2）. Southern blotting analysis and high-throughput genome sequencing verifed that a single copy of rtTA-M2 gene had stably integrated into the zebrafish genome. After induction with doxycycline （Dox）, a strong green fluorescent protein （GFP） was seen in rtTA-transgenic eggs injected with pTRE--EGFP plasmids. The fluorescent signal gradually decreased after the withdrawal of Dox and disappeared. However, leaky expression of GFP was undetectable before Dox- induction. Additionally, transgenic embryos expressing rtTA-M2 exhibited no obvious defects in morphological phenotypes, hatching behavior and expression patterns of developmental marker genes, suggesting that rtTA-M2 had little effect on the development of transgenic zebrafish. Moreover, expressed Dickkopf-1 （DKK1） in pTRE-DKKl-injected embryos led to alterations in the expression of marker genes associated with Wnt signaling. Thus, this rtTA-transgenic zebrafish can be utilized to dissect functions of genes in a temporal manner.