Xiangnong Liu

Genomic sequence of an isolate of Newcastle disease virus isolated from an outbreak in geese: a novel six nucleotide insertion in the non-coding region of the nucleoprotein gene

Summary.We have completely sequenced the genome of an isolate of Newcastle disease virus (NDV) obtained following an outbreak in geese. The genomic sequence consists of 15192 nt, which is six nt longer than the published full length genome of the NDV strains La Sota, B1, Clone-30, Beaudette C and HB V4. The six nt insertion was located in the non-coding region of the nucleoprotein (NP) gene between nt 1646 and nt 1647 of the NDV genome (numbered according to the genomic sequence of the La Sota strain). An additional 22 NDV strains were searched for the existence of this six nt insertion. NDVs in genotypes VI, VII, VIII and IX had this insertion while NDV’s in genotypes I, II, III, IV, and V did not. The significance of this insertion in NDV evolution is discussed.

Phylogenetic and biological characterization of three K1203 (H5N8)-like avian influenza A virus reassortants in China in 2014

Three H5N8 avian influenza viruses isolated from domestic geese in China in 2014 were characterized phylogenetically and biologically. Phylogenetic analysis of the complete genomic sequences of the three isolates from this study and those of 61 other H5N8 viruses retrieved from the GISAID platform indicated that, chronologically and geographically, all H5N8 viruses of the Asian H5N1 HA lineage of clade 2.3.4.4 are the direct descendents of the K1203 (H5N8)-like viruses first isolated in China in 2010. The three viruses from this study shared high sequence similarity in all eight gene segments with three other isolates from China in 2013, and two Korean isolates were distinct from the recently circulating reassortants causing outbreaks in Asia, Europe and the United States in 2014 and 2015. In vitro viral growth curves indicated that these H5N8 viruses replicated to high titers in CEF, DEF, MDCK and A549 cells but to significantly lower titers in Vero cells. Pathogenicity studies in vivo indicated that these viruses were all highly virulent to chickens and mallard ducks, while they varied from moderate to high virulence in mice. Additionally, hemagglutination assays using α-2,3-sialidase-treated goose red blood cells and solid-phase direct binding assays with different glycans demonstrated that the three viruses could bind to both avian-type SAα-2,3Gal and human-type SAα-2,6Gal receptors. Our findings confirmed the progenitor nature of the K1203-like viruses in generating recent prevalent clade 2.3.4.4 H5N8 reassortants, which have caused tremendous damage to the poultry industry and are a potential threat to public health.

A study on synthesis and properties of Fe3O4 nanoparticles by solvothermal method

Magnetic nanoparticles (Fe3O4) were synthesized by the solvothermal method using FeCl3 · 6H2O and ethylene glycol as a reactant. Powder X-ray diffraction, FT-IR, TEM, SEM, and VSM were used to characterize the magnetic particles. The reacting factors, such as reacting time, the concentration of iron source and surfactant, especially the effect of NaAc · 3H2O, were studied. The results indicated that NaAc · 3H2O plays the role not only as a dispersant but also a structure-directing agent. The synthesized Fe3O4 particles showed excellent magnetic property, which made them have potential for application in magnetic nanodevices and biomedicine.

Synthesis and properties of Fe3O4 nanoparticles by sol-vothermal method using iron(III) acetylacetonate

Well dispersed Fe3O4 nanoparticles were synthesized at 180°C by sol-vothermal method, using iron (III) acetylacetonate as iron source and poly-vinilpyrrolidone (PVP) as special surfactant. The factors affecting reaction system, such as reaction temperature and time, the amount of iron source and surfactant are discussed. The synthesized Fe3O4 particles show excellent saturation magnetization and super-paramagnetic properties, demonstrating their potential applicability in magnetic nanodevices and bio-medicine.

Research of mica/Fe3O4 pearlescent pigment by co-precipitation

Experiments on preparation of mica/Fe3O4 pearlescent pigment were performed to discuss influences of several crucial parameters on final products. The samples were characterized by XRD, HRSEM, FTIR and color measurement, the content of Fe3O4 on the mica surface was also analyzed by XPS. It was found that the smoothness, compactness and colour deepness of the coating were influenced by different pH values and temperatures. The optimum preparation parameters of mica/Fe3O4 pearlescent pigment were obtained: the value of pH ≥ 9.2; the concentration of sodium hydroxide was 0.5 mol/l; the concentration ratio of Fe3+ to Fe2+ was 1.6 : 1; the velocity of magnetic stirring was 138 ≤ v ≤ 151 r/min; reaction temperature was 70–80°C; calcination temperature was 350°C and calcination time was 3 h.

Cagelike mesoporous silica encapsulated with microcapsules for immobilized laccase and 2, 4-DCP degradation

In this study, cage-like mesoporous silica was used as the carrier to immobilize laccase by a physical approach, followed by encapsulating with chitosan/alginate microcapsule membranes to form microcapsules of immobilized laccase based on layer-by-layer technology. The relationship between laccase activity recovery/leakage rate and the coating thickness was simultaneously investigated. Because the microcapsule layers have a substantial network of pores, they act as semipermeable membranes, while the laccase immobilized inside the microcapsules acts as a processing plant for degradation of 2,4-dichlorophenol. The microcapsules of immobilized laccase were able to degrade 2,4-dichlorophenol within a wide range of 2,4-dichlorophenol concentration, temperature and pH, with mean degradation rate around 62%. Under the optimal conditions, the thermal stability and reusability of immobilized laccase were shown to be improved significantly, as the removal rate and degradation rate remained over 40.2% and 33.8% respectively after 6cycles of operation. Using mass spectrometry (MS) and nuclear magnetic resonance (NMR), diisobutyl phthalate and dibutyl phthalate were identified as the products of 2,4-dichlorophenol degradation by the microcapsules of immobilized laccase and laccase immobilized by a physical approach, respectively, further demonstrating the degradation mechanism of 2,4-dichlorophenol by microcapsule-immobilized laccase.

PREPARATION, CHARACTERIZATION AND MAGNETIC PROPERTIES OF NANO-Fe3O4 AND COBALT-DOPED NANO-Fe3O4 BY CO-PRECIPITATION METHOD

Pure nano-Fe3O4 and cobalt-doped nano-Fe3O4 particles are successfully synthesized by co-precipitation method using tetramethylammonium hydroxide (TMAOH) as alkali. Several key factors that may affect preparation are carefully discussed such as alkali concentration, alkali dosage, reaction temperature, iron salt solution concentration and dispersant agents. Such nano-Fe3O4 particles prepared have good dispersibility and a very narrow size distribution with the average diameter about 38 nm, which are proved to be cubic spinel Fe3O4 crystal by XRD pattern. It is also found that the addition of PEG-4000 surfactant can improve the dispersibility of nanoparticles. In our work, effects of cobalt dopant concentration on magnetic properties of cobalt-doped nano-Fe3O4 are also discussed. The result shows that the coercivity of cobalt-doped nanoparticles changes greatly with the variation of cobalt dopant concentration. The maximum coercivity reaches as high as 1628 Oe, which is very meaningful for preparation of materials with high coercivity.

Synthesis and characterization of nanocomposites Fe3O4–SiO2–chitosan based on lbl technology

In this paper, the apparent chain-like core-shell structure Fe3O4–SiO2–chitosan nanoparticles was synthesized by two-step method with cross-linking action of glutaraldehyde based on layer-by-layer technology, the composite particles were characterized by IR, XRD, TEM, SEM, EDS and VSM analytical methods, and the synthesis conditions of the product were studied. The results indicated that the diameter of the composite particles is about 106.5 nm, the parietal layer of chitosan is 20 nm, and after crosslinking action of glutaraldehyde, chitosan uniformaly coated the outer surface of Fe3O4–SiO2.

Odd-Even Effect in Synthesis of Mesoporous Silica Using Long-Chain Acyl-L-Alanine Sodium Salt Templating

In this research, hexagonal and cubic mesoporous silica with ordered parallel pore channels was synthesized using odd chain-length N-undecanoyl-L-alanine sodium salt and even chain-length N-lauroyl-L-alanine sodium salt as template respectively. Aminopropylsiloxane was used as the co-structure-directing agents (CSDA). The ordered mesostructure was characterized by infrared spectroscopy, small X-ray diffraction patterns (XRD), scanning electron microscope (SEM), trasmission electron microscope (TEM), and nitrogen sorption analysis. The results indicated that mesoporous silica which was prepared by asymmetric odd chain-length surfactants presented a looser strucuture with large volume than mesoporous silica prepared by the even chain-length surfactant. It led to the transformation from 2D hexagonal (p6mm) phase to cubic (Ia¯3d) mesophase.

A Novel Layered Anchoring Structure Immobilized Cellulase via Covalent Binding of Cellulase on MNPs Anchored by LDHs

In this study, Fe3O4 nanoparticles were first synthesized by co-precipitation method and then layered double hydroxides (LDHs) nanosheets were anchored onto Fe3O4 via an in-situ growth method to prepare LDHs@Fe3O4 carrier. The obtained magnets and LDHs@Fe3O4 carrier were characterized by XRD, FT-IR, N2 adsorption, HRSEM and HRTEM respectively. Using glutaraldehyde as a coupling agent, cellulase was immobilized onto this magnetic carrier by covalent binding. The effects of various parameters on enzyme activity of LDHs@Fe3O4 immobilized cellulase, including cellulase concentration, glutaraldehyde concentration, crosslinking time, pH, cellulase concentration, immobilization time and temperature were discussed in detailed. Moreover, thermal stability and operating stability of the immobilized cellulase were studied, the loaded amount of cellulase was measured, and the degradation performance of methoxychlor (MXC) by layered anchoring structure immobilized cellulase was evaluated.