Polyether-based crystalline multiblock copolymers have been employed as membrane materials for the removal of CO2 from light gases due to their excellent gas permeability and selectivity. However, the influence of the nature of the crystalline and amorphous regions on gas permeability needs to be deeply explored. In this work, the effect of the phase structure, especially the degree of microphase separation (DPS) in the amorphous regions, on the gas transport properties of poly(ether-b-amide) (PEBA) segmented copolymers has been studied. It was found that the amorphous domain consists of two partially mixed phases enriched either with poly(tetramethylene oxide) (PTMO) or with polyamide 1012 (PA1012). The effect of annealing on the microphase structure in the crystalline and amorphous regions was investigated by X-ray scattering techniques. The DPS was found to be inversely correlated with the crystallinity of the hard segments. Gas permeability measurements confirmed that for PEBA membranes with lower crystallinity, weak microphase separation favors gas permeability. All these findings provide a simple method to modulate the degree of microphase separation by varying the crystallinity of the hard segments. Additionally, this work shed light on the synergistic effects of these factors on gas permeability, providing valuable guidance to enhance the performance of gas separation membranes.

Complex phenylethanoid glycosides (PhGs), such as verbascoside and echinacoside, comprise a vital family of natural products with renowned nutraceutical and pharmaceutical significance. Despite the high demand for these compounds across various industries, traditional plant extraction methods yield insufficient quantities, highlighting the need for alternative production methods. Therefore, this paper reports the successful engineering of Saccharomyces cerevisiae cell factories for the efficient production of complex PhGs from glucose. First, key pathway enzymes with enhanced catalytic activities in yeast were primarily screened from various verbascoside-producing plants. Second, intermediate osmanthuside B was produced with a titer of 21.5 ± 1.5 mg/L from glucose by overexpressing several enzymes, including glucosyltransferase RrUGT33 from Rhdiola rosea, acyltransferase SiAT, and 1,3-rhamnosyltransferase SiRT from Sesamum indicum, UDP-L-rhamnose synthase AtRHM2, and 4-coumarate: coenzyme A ligase At4CL1 from Arabidopsis thaliana in a p-coumaric acid-overproducing S. cerevisiae strain. Third, the production of osmanthuside B was further enhanced by increasing the copy number of SiAT and AtRHM2 in genome and diverting L-tyrosine into tyrosol biosynthesis by introducing an aromatic aldehyde synthase PcAAS from Petroselinum crispum with a titer of 320.6 ± 59.3 mg/L. Fourth, the biosynthesis of verbascoside was accomplished by integrating genes CYP98A20 and AtCPR1 into the chromosomes of the osmanthuside B-producing strain, the titer reached 184.7 ± 5.7 mg/L. Furthermore, the overexpression of the glucose-6-phosphate dehydrogenase (ZWF1) led to significantly enhanced verbascoside production to 230.6 ± 11.8 mg/L. The strains were further engineered to produce echinacoside with a titer of 184.2 ± 11.2 mg/L. Finally, the fed-batch fermentation in a 5-L bioreactor yielded 4497.9 ± 285.2 mg/L of verbascoside or 3617.4 ± 117.4 mg/L of echinacoside. This work provides a crucial foundation for the green, industrial, and sustainable production of verbascoside and echinacoside and sets an initial point for the microbial production of other complex PhG derivatives.

In this study, the crystal form transition and semicrystalline morphology evolution of quenched polyamide 1012 (PA1012) during heating were investigated. Quenched PA1012 displayed a pseudohexagonal gamma' form at room temperature, in which the methylene segments adopted a trans conformation, the methylene group directly attached to the amide group was twisted, and the hydrogen bonding pointed in all directions. During heating, the gamma' form gradually transformed into the gamma form as the trans methylene sequences that are away from the amide group further twisted, and the dihedral angle between the amide and methylene plane exhibited a narrow distribution. The transition onset temperature was near the glass transition temperature of quenched PA1012. The semicrystalline morphology of quenched PA1012 was characterized as a loose network consisting of a disordered arrangement of thin lamellae with poorly defined boundaries. As the annealing temperature increased, the lamellae became more perfect and thicker, while the morphological type remained the same.

The pseudohexagonal gamma ' phase of polyamide 1012 can be obtained by melt-quenching and gradually transformed into the gamma form during heating, in which the trans methylene segments away from the amide group are further twisted. What happens during uniaxial stretching? In this work, the multistage structural evolution of the gamma ' phase during uniaxial stretching has been studied by using in situ wide-angle X-ray scattering (WAXS) and Fourier transform infrared spectroscopy (FTIR). The multistage conformational evolution of the gamma ' phase during stretching was studied by quantitative analysis of the infrared progression bands and was found to be closely correlated with the mechanical response during tensile deformation. In the yield stage, the twisted methylene segments in the initial gamma ' phase undergo conformational ordering under stress activation, and the gamma ' phase spontaneously transforms into a defective alpha phase. Furthermore, in the plateau stage, strain induces significant conformational disorder and the transient alpha phase transforms into the most conformationally disordered gamma phase. Finally, at the strain hardening stage, the reversible crystal form transition from the gamma phase to the regular gamma ' phase is induced by stress, accompanied by an obvious conformational ordering process. The stress- and strain-induced conformational torsional motions are found to be completely opposite, with the former inducing conformational order and the latter inducing conformational disorder.

Thepresent work aims to design thermal protocols to generate differentcrystal forms in even-even polyamides. Such structural controlcan lead to tailoring of their properties. To achieve our objective,we have chosen low molecular weight (M (n)) Polyamide 1012 (PA1012) because its crystal forms can be more easilycontrolled by changing cooling rates after erasing thermal historyin comparison with high M (n) PA1012. Whenthe chosen PA1012 was slowly cooled after erasing thermal history(e.g., 2 & DEG;C/min) to a temperature where it had crystallized untilsaturation (i.e., 150 & DEG;C), the standard & alpha; form could thenbe obtained when the sample was further cooled to room temperature(RT) at any rate. However, if the sample was first cooled at fastercooling rates (>20 & DEG;C/min) until 150 & DEG;C, two types ofdifferentcrystal forms could be obtained upon subsequent cooling to RT. Combiningself-nucleation (SN) experiments and wide-angle X-ray diffraction(WAXD) results, we found that the formation of locally ordered H-bondsat high temperatures (during crystallization from the melt) directlyaffected the final room-temperature crystal form. It was found thatthe lower crystallization degree and smaller crystal size of the lessthermodynamically stable & gamma;& PRIME; form films possess not onlygood toughness and elongation at break but also excellent transparencyas well as higher gas permeability coefficient with better gas selectionproperties. Among them, the & gamma;& PRIME; form has a broader marketprospect by endowing PA1012 films with excellent mechanical propertiesand gas transport properties to produce transparent membranes forbiogas purification.

Glycosylation reactions mediated by UDP-glycosyltransferases (UGTs) are common post-modifications involved in plant secondary metabolism and significantly improve the solubility and bioactivity of aglycones. Penstemon barbatus is rich in phenylethanoid glycosides (PhGs), such as echinacoside and verbascoside. In this study, a promiscuous glycosyltransferase UGT84A95 was identified from P. barbatus. In vitro enzyme assays showed that UGT84A95 catalyzed the glucosylation of the phenol hydroxyl group of PhGs efficiently as well as other structurally diverse phenolic glycosides, including flavonoids, terpenoids, stilbene glycosides, coumarins, and simple polyphenols. By using UGT84A95, 12 glycosylated products were prepared and structurally identified by NMR spectroscopy, among which 7 are new compounds. These findings suggest that UGT84A95 could be a potential biocatalyst to synthesize multi-glycosylated glycosides.

Verbascoside, which was first discovered in 1963, is a well-known phenylethanoid glycoside (PhG) that ex-hibits antioxidant, anti-inflammatory, antimicrobial, and neuroprotective activities and contributes to the therapeutic effects of many medicinal plants. However, the biosynthetic pathway of verbascoside remains to be fully elucidated. Here, we report the identification of two missing enzymes in the verbascoside biosyn-thesis pathway by transcriptome mining and in vitro enzymatic assays. Specifically, a BAHD acyltransfer-ase (hydroxycinnamoyl-CoA:salidroside hydroxycinnamoyltransferase [SHCT]) was shown to catalyze the regioselective acylation of salidroside to form osmanthuside A, and a CYP98 hydroxylase (osmanthuside B 3,30-hydroxylase [OBH]) was shown to catalyze meta-hydroxylations of the p-coumaroyl and tyrosol moieties of osmanthuside B to complete the biosynthesis of verbascoside. Because SHCTs and OBHs are found in many Lamiales species that produce verbascoside, this pathway may be general. The findings from the study provide novel insights into the formation of caffeoyl and hydroxytyrosol moieties in natural product biosynthetic pathways. In addition, with the newly acquired enzymes, we achieved heterologous production of osmanthuside B, verbascoside, and ligupurpuroside B in Escherichia coli; this work lays a foundation for sustainable production of verbascoside and other PhGs in micro-organisms.

In this study, we report the characterization of three glycosyltransferases involved in the biosynthesis of ligupurpuroside B, a complex acylated phenolic glycoside in Ligustrum robustum. UGT85AF8 catalyzed the formation of salidroside from tyrosol. UGT79G7, an osmanthuside A 1,3-rhamnosyltransferase, and UGT79A19, an osmanthuside B 1,4-rhamnosyltransferase, sequentially converted osmanthuside A into ligupurpuroside B. Orthologs of UGT79G7 were also discovered from other plants producing verbascoside. These rhamnosyltransferases expand the toolbox for the biosynthesis of natural products with various sugar chains.