αh-GeSe: a multifunctional semiconductor combining auxeticity and piezoelectricity.

Multifunctional materials with outstanding performance have enormous potential applications in the next generation of nanodevices. Using first principles calculations, we design a series of multifunctional two-dimensional materials in monolayer αh-GeSe (, = 1, 2) that combine auxeticity and piezoelectricity. Due to the similar local structures of α-GeSe and h-GeSe, monolayer αh-GeSe can be designed through the combination of these two materials.

Coexistence of ferroelectricity and ferromagnetism in hex-GeS nanowires.

The existence of one-dimensional (1D) ferroelectricity and ferromagnetism provides an opportunity to expand the field of research in low-dimensional magnetoelectric and multiferroics and explore the future development of high-performance nanometer devices. Here, we predict a novel 1D ferroelectric hex-GeS nanowire with coexisting ferromagnetism. The electric polarization comes from the atomic displacements between Ge and S atoms, and it exhibits a far-higher than room temperature ferroelectric Curie temperature Ec = 830 K.

2D SnO2 Nanosheets: Synthesis, Characterization, Structures, and Excellent Sensing Performance to Ethylene Glycol.

Two dimensional (2D)SnO2 nanosheets were synthesized by a substrate-free hydrothermal route using sodium stannate and sodium hydroxide in a mixed solvent of absolute ethanol and deionized water at a lower temperature of 130 °C. The characterization results of the morphology, microstructure, and surface properties of the as-prepared products demonstrated that SnO2 nanosheets with a tetragonal rutile structure, were composed of oriented SnO2 nanoparticles with a diameter of 6-12 nm. The X-ray diffraction (XRD) and high-resolution transmission electron microscope (FETEM) results demonstrated that the dominant exposed surface of the SnO2 nanoparticles was (101), but not (110).

The Effect of Eu Doping on Microstructure, Morphology and Methanal-Sensing Performance of Highly Ordered SnO₂ Nanorods Array.

Layered Eu-doped SnO₂ ordered nanoarrays constructed by nanorods with 10 nm diameters and several hundred nanometers length were synthesized by a substrate-free hydrothermal route using alcohol and water mixed solvent of sodium stannate and sodium hydroxide at 200 °C. The Eu dopant acted as a crystal growth inhibitor to prevent the SnO₂ nanorods growth up, resulting in tenuous SnO₂ nanorods ordered arrays. The X-ray diffraction (XRD) revealed the tetragonal rutile-type structure with a systematic average size reduction and unit cell volume tumescence, while enhancing the residual strain as the Eu-doped content increases.

Well-aligned Nd-doped SnO2 nanorod layered arrays: preparation, characterization and enhanced alcohol-gas sensing performance.

Well-oriented neodymium doped SnO2 layered nanorod arrays were synthesized by a substrate-free hydrothermal route using sodium stannate and sodium hydroxide at 210 °C. The morphology and phase structure of the Nd-doped SnO2 nanoarrays were investigated by X-ray powder diffraction spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman scattering spectroscopy, X-ray photoelectron spectroscopy and the BET method. The results demonstrated that the Nd-doped SnO2 layered nanorod arrays showed a unique nanostructure combined together with double layered arrays of nanorods with a diameter of 12 nm and a length of several hundred nanometers.

Constitutive expression of Yarrowia lipolytica lipase LIP2 in Pichia pastoris using GAP as promoter.

A gene encoding Yarrowia lipolytica lipase LIP2 (YlLIP2) was cloned into a constitutive expression vector pGAPZαA and electrotransformed into the Pichia pastoris X-33 strain. The high-yield clones obtained by high copy and enzyme activity screening were chosen as the host strains for shaking flask and fermentor culture. The results showed that glucose was the optimum carbon source for YlLIP2 production, and the maximum hydrolytic activity of recombinant YlLIP2 reached 1,315 U/ml under the flask culture at 28 °C, pH 7.

[Heterologous expression and characterization of Yarrowia lipolytica lipase 4 and lipase 5 in Pichia pastoris].

Objective: To clone cDNA sequences of lipase 4 (LIP4) and lipase 5 (LIPS), analyze gene structures and express them in Pichia pastoris so as to investigate their enzymatic characteristics.

Methods: We first cloned cDNA sequences of LIP4 and LIP5 by reverse transcription PCR and analyzed their gene structures by SignalP 3.0.

Intracellular expression of Vitreoscilla hemoglobin improves production of Yarrowia lipolytica lipase LIP2 in a recombinant Pichia pastoris.

The Yarrowia lipolytica lipase LIP2 (YlLIP2) gene lip2 and Vitreoscilla hemoglobin gene vgb were co-expressed in Pichia pastoris, both under the control of AOX1 promoter, in order to alleviate respiration limitation under conditions of high cell-density fermentation and enhance YlLIP2 production. The results showed that recombinant P. pastoris strains harboring the lip2 and vgb genes (VHb(+)) displayed higher biomass and YlLIP2 activity than control strains (VHb(-)).

Cloning, expression and characterization of a new lipase from Yarrowia lipolytica.

Bioinformatic analysis of the Yarrowia lipolytica CLIB122 genome has revealed 18 putative lipase genes all of which were expressed in Escherichia coli and screened for hydrolyzing activities against p-nitrophenyl-palmitate. One positive transformant containing an ORF of 1,098 bp encoding a protein of 365 amino acids was obtained. To characterize its enzymatic properties, the lipase gene was functionally expressed in Pichia pastoris.

Preparation of a whole-cell biocatalyst of Aspergillus niger lipase and its practical properties.

Aspergillus niger lipase (ANL), a widely used hydrolase, was displayed for the first time on the surface of Saccharomyces cerevisiae using a-agglutinin as an anchor protein. Localization of ANL on the cell surface was confirmed by immunofluorescence microscopy. The displayed ANL was confirmed to be active toward tributyrin and p-nitrophenyl caprylate (pNPC).

[Gene cloning, codon optimization and functional expression of Yarrawia lipolytica lipase Lip1].

Objective: To implement inducible and constitutive over-expression of Yarrowia lipolytica lipase gene lipl in Pichia pastoris using codon optimization.

Methods: We cloned Y. lipolytica lipase gene lip1 according to codon bias of P.

Surface display of active lipases Lip7 and Lip8 from Yarrowia lipolytica on Saccharomyces cerevisiae.

Lipase has been used widely in industry. In this study, we have constructed two recombinant Saccharomyces cerevisiae strains displaying two active lipases on the cell surface by cell surface engineering. The genes encoding Yarrowia lipolytica lipases Lip7 and Lip8 were fused with the gene encoding small binding subunit Aga2 of a-agglutinin.

Surface display of active lipase in Saccharomyces cerevisiae using Cwp2 as an anchor protein.

Lipase Lip2 from Yarrowia lipolytica was displayed on the cell surface of Saccharomyces cerevisiae using Cwp2 as an anchor protein. Successful display of the lipase on the cell surface was confirmed by immunofluorescence microscopy and halo assay. The length of linker sequences was further examined to confirm that the correct conformation of Lip2 was maintained.

[Cell surface display of Yarrowia lipolytica lipase Lip2 in Saccharomyces cerevisiae with a-agglutinin as carrier protein].

Objective: In order to display extracellular.lipase Lip2 from Yarrowia lipolytica on the surface of yeast Saccharomyces cerevisiae for whole cell catalysts.

Methods: The mature Lip2 encoding fragment was amplified from Yarrowia lipolytica total DNA, and was inserted into the 3'terminal of AGA2 to give the plasmid pCTLIP2 for surface display of Lip2.