Using anodized TiO 2 nanotubes as the starting materials, unique structural single-crystalline anatase TiO 2 dous assembled microspheres are fabricated by a hydrothermal method. The single-crystalline anatase TiO 2 dou is formed through the transformation of a TiO 2 nanotube, which is formed through a complex process including the expansion of the nanotube, dissolution-recrystallization, and recombination. The opening and hollow structural dou exposes one {001} face and eight {101} faces, which displays excellent photocatalytic activity. And it is also envisaged to be of high promise for many other potential applications. The approach might be exploited for the synthesis of single-crystalline nanomaterials with special morphologies.

No abstract

An electrospun acid-base pair solid dispersion in the form of core-shell nanofibers was developed for improving the dissolution of quercetin (8 cm× 4 cm, 600 dpi)In this work, electrospinning was used to fabricate core-shell nanofibers containing acid-base pairs. Quercetin was used as a model active ingredient. To exploit its solubility in basic conditions, a solution of quercetin, polyvinylpyrrolidone (PVP) and sodium hydroxide was used as the core fluid, and one consisting of citric acid and PVP as the shell fluid. Scanning and transmission electron microscopy demonstrated that core-shell nanofibers with linear morphologies were obtained, without beads or 10 spindles. X-ray diffraction showed that quercetin was present in the fibers in an amorphous state; Fourier transform infrared spectroscopy indicated this may be a result of hydrogen bonding between the drug and the polymer matrix. In in vitro dissolution tests the drug was found to be released immediately when the fibers encountered an aqeuous medium. There was no change in the pH of the medium after dissolution, as a result of the presence of the acid-base pair. This provides a new strategy for improving the 15 dissolution behavior of poorly water-soluble drugs using polymeric nanostructures.

A new polysubstituted benzaldehyde derivative, ethyl 5-ethoxy-2-formyl-3-hydroxy-4-methylbenzoate (1), was isolated from the co-culture broth of two mangrove fungi (strains Nos. K38 and E33) isolated from the South China Sea coast. The structure of 1 was determined by comprehensive spectroscopic methods, especially 2D NMR techniques. Primary bioassays showed that compound 1 at 0.25 mM inhibited Fusarium graminearum, Gloeosporium musae, Rhizoctonia solani Kuhn, and Phytophthora sojae (Kaufmann & Gerdemann) in 12. 06, 11.57, 10.21, and 8.50 mm diameters, respectively. Keywords: co-culture, marine mangrove fungus, polysubstituted benzaldehyde, antifungal activity.The rediscovery of known secondary metabolites is a chronic problem in natural products chemistry, suggesting overall that more efficient methods need to be developed or adopted to enhance the discovery of new natural compounds [1,2].According to the hypothesis that some special microbial secondary metabolites may only be produced in response to interactions with other microbes, the method of culturing different microbes together has been used for searching for novel natural products in recent years. One of the first documented examples of novel natural compound obtained from marine microbial co-culturing was reported by the Fenical laboratory at the Scripps Institution of Oceanography. To date, they reported at least seven new biologically active compounds by co-culture studies of marine-derived microorganisms, pestalone [3], libertellenones A-D [4], and emericellamides A and B [5]. Additionally, three new alkaloids, marinamides A and B [6] and aspergicin, were isolated from the mixed cultured mycelia of two marine-derived mangrove epiphytic fungi [7]. During our co-culture studies with marine mangrove fungi, we investigated the secondary metabolites produced from the co-culture broth of two mangrove fungus strains E33 and K38 isolated from the South China Sea coast, which yielded a new antifungal xanthone derivative, 8-hydroxy-3-methyl-9-oxo-9H-xanthene-1-carboxylic acid methyl ether [8], and a new cytotoxic nonadride analogue, (-)-byssochlamic acid bisdiimide [9].In the study, we describe the isolation and identification of another new compound from the co-culture broth of the same mangrove fungi E33 and K38, a polysubstituted benzaldehyde named ethyl 5-ethoxy-2-formyl-3-hydroxy-4-methylbenzoate. Its antifungal effects against four plant pathogenic fungi were measured in vitro.A 200 L fermentation broth was concentrated and extracted with ethyl acetate. The extract was repeatedly chromatographed on silica gel to obtain compound 1 from the 10% ethyl acetate-petroleum fraction as colorless needles. Compound 1 has the molecular formula C 13 H 16 O 5 , determined by FAB-MS (m/z 253 [M + H] + ) and elemental analysis, which led to the conclusion that compound 1 had five degrees of unsaturation. The 13 C NMR spectrum of 1 (Table 1) exhibited 13 carbon signals attributable to three methyl, two methene, two methine, and six quaternary carbon atoms according ...

No abstract

Furfural-tolerant strain is essential for the fermentative production of biofuels or chemicals from lignocellulosic biomass. In this study, Zymomonas mobilis CP4 was for the first time subjected to error-prone PCR-based whole genome shuffling, and the resulting mutants F211 and F27 that could tolerate 3 g/L furfural were obtained. The mutant F211 under various furfural stress conditions could rapidly grow when the furfural concentration reduced to 1 g/L. Meanwhile, the two mutants also showed higher tolerance to high concentration of glucose than the control strain CP4. Genome resequencing revealed that the F211 and F27 had 12 and 13 single-nucleotide polymorphisms. The activity assay demonstrated that the activity of NADH-dependent furfural reductase in mutant F211 and CP4 was all increased under furfural stress, and the activity peaked earlier in mutant than in control. Also, furfural level in the culture of F211 was also more rapidly decreased. These indicate that the increase in furfural tolerance of the mutants may be resulted from the enhanced NADH-dependent furfural reductase activity during early log phase, which could lead to an accelerated furfural detoxification process in mutants. In all, we obtained Z. mobilis mutants with enhanced furfural and high concentration of glucose tolerance, and provided valuable clues for the mechanism of furfural tolerance and strain development.

No abstract

No abstract