Characterization of Active Packaging Films Made from Poly(Lactic Acid)/Poly(Trimethylene Carbonate) Incorporated with Oregano Essential Oil.

Antimicromial and antioxidant bioactive films based on poly(lactic acid)/poly(trimenthylene carbonate) films incorporated with different concentrations of oregano essential oil (OEO) were prepared by solvent casting. The antimicrobial, antioxidant, physical, thermal, microstructural, and mechanical properties of the resulting films were examined. Scanning electron microscopy analysis revealed that the cross-section of films became rougher when OEO was incorporated into PLA/PTMC blends. Differential scanning calorimetry analysis indicated that crystallinity of PLA phase decreased by the addition of OEO, but this did not affect the thermal stability of the films. Water vapor permeability of films slightly increased with increasing concentration of OEO. However, active PLA/PTMC/OEO composite films showed adequate barrier properties for food packaging application. The antimicrobial and antioxidant capacities were significantly improved with the incorporation of OEO (p < 0.05). The results demonstrated that an optimal balance between the mechanical, barrier, thermal, antioxidant, and antimicrobial properties of the films was achieved by the incorporation of 9 wt % OEO into PLA/PTMC blends.

A facile and mild synthesis of trisubstituted allylic sulfones from Morita-Baylis-Hillman carbonates.

An efficient and catalyst-free synthesis of trisubstituted allylic sulfones through an allylic sulfonylation reaction of Morita-Baylis-Hillman (MBH) carbonates with sodium sulfinates has been developed. Under the optimized reaction conditions, a series of trisubstituted allylic sulfones were rapidly prepared in good to excellent yields (71%-99%) with good to high selectivity (Z/E from 79:21 to >99:1). Compared with known synthetic methods, the current protocol features mild reaction temperature, high efficiency and easily available reagents.

The synthesis and characterization of hydroxyapatite-ß-alanine modified by grafting polymerization of γ-benzyl-L-glutamate-N-carboxyanhydride.

In this study, hydroxyapatite (HAP) was surface-modified by the addition of ß-alanine (ß-Ala), and the ring-opening polymerization of γ-benzyl-L-glutamate-N-carboxy-anhydride (BLG-NCA) was subsequently initiated. HAP containing surface poly-γ-benzyl-L-glutamates (PBLG) was successfully prepared in this way. With the increase of PBLG content in HAP-PBLG, the solubility of HAP-PBLG increased gradually and it was ultimately soluble in chloroform. HAP-PLGA with surface carboxyl groups was obtained by the catalytic hydrogenation of HAP-PBLG. In the process of HAP modification, the morphology changes from rod to sheet and from flake to needle. The effect of BLG-NCA concentration on the character of hydroxyapatite-ß-alanine-poly(γ-benzyl-L-glutamate) (HAP-PBLG) was investigated. The existence of amino acids on the HAP surfaces was confirmed in the resulting Fourier transform infrared (FTIR) spectra. The resulting powder X-ray diffraction patterns indicated that the crystallinity of HAP decreased when the ratio of BLG-NCA/HAP-NH2 increased to 20/1. Transmission electron microscopy (TEM) indicated that the particle size of HAP-PBLG decreased significantly and that the resulting particles appeared less agglomerated relative to that of the HAP-NH2 crystals. Furthermore, ¹H-NMR spectra and FTIR spectra revealed that hydroxyapatite-ß-alanine-poly (L-glutamic acid) (HAP-PLGA) was able to successfully bear carboxylic acid groups on its side chains.

Ring-opening polymerization of L-lactic acid O-carboxyanhydrides initiated by alkoxy rare earth compounds.

The ring-opening polymerization of L-lactic acid O-carboxyanhydrides was initiated by triisopropoxyneodymium in toluene-THF mixtures. Typically, high yields and relatively high molecular weight PLAs were obtained within 4 h at 25 °C. The reaction was highly controllable and easy to conduct, and the molecular weight distribution of the PLAs was rather narrow (Mw/Mn = 1.10-1.36). NMR analysis showed that one end of the PLA chain consisted of an isopropoxy group, while the other end of the chain contained a hydroxyl group. Due to their availability and high polymerizability, Lac-OCAs are promising monomers for the preparation of tailored architectures derived from well-defined PLAs.

Highly efficient asymmetric anti-Mannich reactions of carbonyl compounds with N-carbamoyl imines catalyzed by amino-thiourea organocatalysts.

A series of pyrrolidine-based organocatalysts which bear three synergistic features, i.e. secondary amino group, various H-bond donor groups at the 4-position and a stereocontrol silyl ether group at the α-position of the pyrrolidine nitrogen atom, were developed. They were screened in anti-Mannich reactions of carbonyl compounds with preformed or in situ generated N-protected α-imino ethylglyoxylate and aldehydes with preformed or in situ generated N-carbamoyl imines. The influence of H-bond donor ability at the 4-position was also investigated. Among all the catalysts, 2a was identified as a general efficient organocatalyst suitable for various types of anti-Mannich reactions and broad substrate scope. Excellent results (up to 98% yield, >99% ee and >99 : 1 dr) were achieved with 5 mol% catalyst load. Sulfones with ortho substituents or very strong withdrawing groups on the aromatic ring, which have been regarded as challenging substrates in the direct anti-Mannich reactions of aldehydes with in situ generated N-carbamoyl imines, also worked well. The optimization of our catalytic system also offered alternative and easily operational protocols to access anti-Mannich products with orthogonal N-Boc or N-Cbz protecting groups.

Noroleanane-type triterpenoids from Dolichos trilobus L. and their anti-α-glucosidase activities.

Falcatane A (1) and B (2), 4-oxo-3,24-dinor-2,4-secooleanane- and 3-oxo-24- noroleanane-type triterpenoids, together with seven known triterpenoids involving 2-hydroxy-3-oxo-24-noroleana-1,4,12-trien-28-oic acid (3) and oleanolic acid (4), were separated from the ethyl acetate roots extract of Dolichos trilobus using the column chromatography of silica gel, MCI gel, and Sephadex LH-20. The compounds were determined by analysis of IR, NMR spectroscopic data and mass spectrometry. In the bioassay, all isolates showed varying degree of the α-glucosidase inhibitory activity except compound 2.

Effect of Different Binders on the Electrochemical Performance of Metal Oxide Anode for Lithium-Ion Batteries.

When testing the electrochemical performance of metal oxide anode for lithium-ion batteries (LIBs), binder played important role on the electrochemical performance. Which binder was more suitable for preparing transition metal oxides anodes of LIBs has not been systematically researched. Herein, five different binders such as polyvinylidene fluoride (PVDF) HSV900, PVDF 301F, PVDF Solvay5130, the mixture of styrene butadiene rubber and sodium carboxymethyl cellulose (SBR+CMC), and polyacrylonitrile (LA133) were studied to make anode electrodes (compared to the full battery). The electrochemical tests show that using SBR+CMC and LA133 binder which use water as solution were significantly better than PVDF. The SBR+CMC binder remarkably improve the bonding capacity, cycle stability, and rate performance of battery anode, and the capacity retention was about 87% after 50th cycle relative to the second cycle. SBR+CMC binder was more suitable for making transition metal oxides anodes of LIBs.

A facile direct anti-selective catalytic asymmetric Mannich reaction of aldehydes with preformed N-Boc and N-Cbz imines.

Anti-selective Mannich reactions of N-Boc and N-Cbz protected imines with unmodified aldehydes proceeded smoothly under the catalysis of a secondary amine-thiourea catalyst, which led to high yields (70%-95%) and excellent enantioselectivity (up to 96 : 4 dr and >99% ee) under conventional organic synthetic operations.