3-Hydroxypropionic acid (3-HP) is an important platform chemical in organic synthesis. Traditionally, 3-HP was produced by chemical methods and fermentation process. In this work, a novel enzymatic method was developed for green synthesis of 3-HP. A yeast strain harboring nitrile-hydrolyzing enzyme was newly isolated from environmental samples using 3-hydroxypropionitrile (3-HPN) as the sole nitrogen source. It was identified to be Meyerozyma guilliermondii CGMCC12935 by sequencing of the 18S ribosomal DNA and internal transcribed spacer, together with analysis of the morphology characteristics. The catalytic properties of M. guilliermondii CGMCC12935 resting cells were determined, and the optimum activity was achieved at 55 °C and pH 7.5. The enzyme showed broad substrate specificity towards nitriles, especially 3-HPN, aminoacetonitrile and 3-cyanopyridine. The presence of Ag, Pb and excess substrate inhibited the enzyme activity, whereas 5% (v/v) ethyl acetate had a positive effect on the enzyme activity. M. guilliermondii CGMCC12935 resting cells by addition of 3% glucose could thoroughly hydrolyze 500 mM 3-HPN into 3-HP within 100 h and the maximal accumulative production of 3-HP reached 216.33 mM, which was over twofolds than the control group with no additional glucose. And this work would lay the foundation for biological production of 3-HP in industry.
In response to the defects of easy delamination, poor impact resistance, and low toughness in laminates, intra-layer aramid/glass hybrid weft-knitted reinforced composites without lamination were designed and prepared. This paper investigated the tensile, bending, and impact response of aramid/glass hybrid weft-knitted reinforced composites. Homogeneous and hybrid composites with glass: aramid hybrid ratios of 1:1, 2:1, 3:1, and hybrid modes of transverse hybrid, oblique hybrid, and vertical interlocking hybrid were prepared by vacuum resin transfer molding (VARTM) technique. The tensile and bending properties were evaluated from stress, modulus, and strain/deflection, and a scanning electron microscope (SEM) was employed. The impact response was analyzed from peak force, maximum displacement, and energy absorption. The results confirm that interlacing brittle glass yarns with aramid yarns exhibits a positive hybrid effect. The ratios of 50%, 33%, and 25% aramid fiber in the transverse hybrid enhanced the longitudinal strength by 72.86%, 52.13%, and 22.01%. The mechanical properties of the oblique hybrid are similar in warp and weft direction; by contrast, the other two hybrid methods demonstrate mechanical anisotropy. This article implements the preparation and mechanical properties research of non-laminated hybrid composites based on weft-knitted structures, which broadens the design and selection of prefabricated components for hybrid composites.
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