Portibacter marinus sp. nov., isolated from the sediment on the surface of plastics and proposal of a novel genus Neolewinella gen. nov. based on the genome-based phylogeny of the family Lewinellaceae.

A Gram-stain-negative, rod-shaped and orange-pigmented bacterial strain designated 10MBP4-2-1T was isolated from the sediment on the surface of a plastic straw collected from oyster-farming areas in Quanzhou Bay, PR China. Catalase activity and oxidase activity were positive. Flexirubin-type pigment was absent. The 16S rRNA gene of strain 10MBP4-2-1T showed highest sequence similarity to Portibacter lacus YM8-076T of 98.3 %. Phylogenetic analysis based on 16S rRNA gene sequences and 120 conserved concatenated proteins indicated that strain 10MBP4-2-1T was affiliated to the genus Portibacter and formed a monophyletic clade with P. lacus YM8-076T. The digital DNA-DNA hybridization, average nucleotide identity and average amino acid identity values between strain 10MBP4-2-1T and P. lacus YM8-076T were estimated to be 17.7, 70.4 and 70.3 %, respectively. The respiratory quinone was menaquinone 7. The major fatty acid composition was iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c). The draft genome size was 5 191 941 bp with DNA G+C content of 39.2 %. Based on phylogenetic analyses and whole genomic comparisons, strain 10MBP4-2-1T represents a novel species, for which the name Portibacter marinus sp. nov. is proposed. The type strain is 10MBP4-2-1T (=MCCC 1K07073T=KCTC 92101T). Additionally, phylogeny and whole genomic comparison of the family Lewinellaceae placed Lewinella cohaerens and the remaining Lewinella (currently comprising 11 species) in two clearly distinguishable clades recognized at the genus level. Thus, a novel genus named Neolewinella gen. nov. is proposed to accommodate the 11 species. Our study provides a taxonomic framework for the family Lewinellaceae based on genomic data.

The effect of prolonged holding time on the mechanical property and microstructural property of lithium disilicate glass-ceramic.

Repeat firing produces uncertainty about stabilizing lithium disilicate glass-ceramic (LDGC) material properties, even though prolonged holding time can enhance the mechanical property of LDGC during a single firing cycle. However, the effect of prolonged holding time and repeat firing on the mechanical property and microstructure of LDGC is not fully understood. In the present study, three groups of LDGC material were created: (i) extension of holding time (7 vs. 14 vs. 28 min) at 780-800 °C; (ii) holding time extension (7 vs. 14 min) and dual sintering at 800-820 °C, respectively; (iii) dual sintering with prolonged holding time (7 vs. 14 min) at 820-840 °C. The nano-indenter test revealed that prolonged holding time (14 and 28 min) promoted the enhancement of LDGC hardness and Young's modulus. X-ray photoelectron spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy confirmed that prolonged holding time increased and stabilized LD phase in LDGC, as well as induced residual compressive stress. Scanning electron microscopy showed that prolonged holding time increased LD crystal grains homogeneously and facilitated LDGC to form dense interlocking structure without enlarging crystal size grains significantly. In contrast, LDGC that dual sintered alone at 820-840 °C possessed inferior mechanical properties, coupled with heterogeneous crystal phases, residual tensile stress, and melted crystals grains in the porous microstructure. Interestingly, these deteriorated properties of LDGC caused by dual sintering alone could be counteracted by prolonging the holding time. Nevertheless, the LDGC materials displayed an excellent biocompatibility throughout the study. This study identified that prolonged holding time during repeated firing cycles stabilized LD phase and crystal grain size of LDGC, thus enhanced the mechanical properties, which provided a new insight to extend the repeat fired restoration longevity of LDGC. Graphical abstract.

mPEG-icariin nanoparticles for treating myocardial ischaemia.

Icariin (ICA), a major active ingredient from Chinese medicine, has unique pharmacological effects on ischaemic heart disease. However, its hydrophobic property limits its administration and leads to poor efficacy. This work aimed to change its hydrophobic property and improve the treatment efficacy. We designed a new nano-drug to increase the ICA delivery. ICA was modified with hydrophilic polyethylene glycol monomethyl ether (mPEG) by a succinic anhydride linker to form a polyethylene glycol-icariin (mPEG-ICA) polymer. The structure of this polymer was identified by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The content of ICA in the polymer was 32% as detected by ultraviolet spectrophotometry. mPEG-ICA nanoparticles, of 143.3 nm, were prepared by the dialysis method, and zeta potential was 0.439 mV by dynamic light scattering. The nanoparticles had a spherical shape on transmission electron microscopy. In media with pH 7.4 and 6.8, ICA release from mPEG-ICA nanoparticles after 72 h was about 0.78% and 64.05%, respectively, so the ICA release depended on the release media pH. On MTT and lactate dehydrogenase activity assay, mPEG-ICA nanoparticles could reduce cell damage induced by oxgen-glucose deprivation. Hoechst 33258 staining and TUNEL and AnnexinV-FITC/PI double staining showed that ICA nanoparticles could increase the activity of H9c2 cardiomyocytes under oxgen-glucose deprivation conditions by decreasing apoptosis. ICA modified by hydrophilic mPEG could improve its efficacy.