生物酶改善溶解浆性能的研究进展

溶解浆由高纯度纤维素组成,用于制造再生纤维素纤维、纤维素酯、纤维素醚等材料。溶解浆性能的好坏对后续产品的生产和加工性能有着很大的影响,其中α-纤维素含量、半纤维素含量、浆粕粘度、灰分、过渡金属离子含量、纤维的物理形态、纤维素分子量分布以及溶解浆的反应性能是其重要的性能指标。生物酶因其绿色、温和、高效的特点,在改善溶解浆性能方面有很好的应用前景,并进行了大量的研究。文中介绍了溶解浆的主要性能指标和改善溶解浆性能的生物酶,重点介绍了纤维素酶和木聚糖酶在改善溶解浆性能方面的应用和研究进展,指出了生物酶改善溶解浆性能目前存在的主要问题,提出了该领域的主要研究方向,并对生物酶处理改善溶解浆性能的技术进行了展望。

Fibroblast growth factor 5 overexpression ameliorated lipopolysaccharide-induced apoptosis of hepatocytes through regulation of the phosphoinositide-3-kinase/protein kinase B pathway

Background:Sepsis is a systemic inflammatory syndrome induced by several infectious agents.Multiple organs are affected by sepsis,including the liver,which plays an important role in metabolism and immune homeostasis.Fibroblast growth factors(FGFs)participate in several biological processes,although the role of FGF5 in sepsis is unclear.Methods:In this study,lipopolysaccharide(LPS)was administrated to mice to establish a sepsis-induced liver injury.A similar in vitro study was conducted using L-02 hepatocytes.Western blot and immunohistochemistry staining were performed to evaluate the FGF5 expression level in liver tissues and cells.Inflammatory cell infiltrations,cleaved-caspase-3 expressions,reactive oxygen species and levels of inflammatory cytokines were detected by immunofluorescence,dihydroethidium staining,and reverse transcription quantitative polymerase chain reaction analysis,respectively.Flow cytometry was used to detect the apoptosis level of cells.In addition,ribonucleic acid(RNA)-sequencing was applied to explore the possible mechanism by which FGF5 exerted effects.Results:LPS administration caused FGF5 down-regulation in the mouse liver as well as in L-02 hepatocytes.Additionally,with FGF5 overexpression,liver injury and the level of hepatocyte apoptosis were ameliorated.Further,RNA sequencing performed in hepatocytes revealed the phosphoinositide-3-kinase/protein kinase B(PI3K/AKT)pathway as a possible pathway regulated by FGF5.This was supported using an inhibitor of the PI3K/AKT pathway,which abrogated the protective effect of FGF5 in LPSinduced hepatocyte injury.Conclusion:The anti-apoptotic effect of FGF5 on hepatocytes suffering from LPS has been demonstrated and was dependent on the activation of the PI3K/AKT signaling pathway.

Axiotaxy driven growth of belt-shaped InAs nanowires in molecular beam epitaxy

In this study,we demonstrate the axiotaxy driven growth of belt-shaped InAs nanowires using Au catalysts by molecular beam epitaxy.It is found that,the zinc-blende structured InAs nanowires,with the features of[113]growth direction and extensive{110}side-surfaces,are induced by catalysts in Au–In α phase through the axiotaxy growth,in which the lattice mismatch between the projections of atomic planes onto nanowire/catalyst interfaces is minimized by forming extraordinary tilted interfaces.Our atomic-resolution in situ TEM heating experiments show that the catalysts remained in the solid state of Au–In α phase during the axiotaxy growth,by which the vapor–solid–solid growth mechanism can be confirmed.Through manipulating the growth direction,this unusual growth mechanism can provide a practical pathway to control the morphology of the low-dimensional nanomaterials,from conventional nanowires to belt-shaped nanowires utilizing a significant lateral growth,simply using nanoparticles as catalyst.

Self-frequency-conversion nanowire lasers

Semiconductor nanowires(NWs)could simultaneously provide gain medium and optical cavity for performing nanoscale lasers with easy integration,ultracompact footprint,and low energy consumption.Here,we report Ⅲ-Ⅴsemiconductor NW lasers can also be used for self-frequency conversion to extend their output wavelengths,as a result of their non-centrosymmetric crystal structure and strongly localized optical field in the NWs.From a GaAs/In0.16Ga0.84As core/shell NW lasing at 1016 nm,an extra visible laser output at 508 nm is obtained via the process of second-harmonic generation,as confirmed by the far-field polarization dependence measurements and numerical modeling.From another NW laser with a larger diameter which supports multiple fundamental lasing wavelengths,multiple self-frequency-conversion lasing modes are observed due to second-harmonic generation and sum-frequency generation.The demonstrated self-frequency conversion of NW lasers opens an avenue for extending the working wavelengths of nanoscale lasers,even to the deep ultraviolet and THz range.

Nanowire-assisted microcavity in a photonic crystal waveguide and the enabled high-efficiency optical frequency conversions

We report an indium phosphide nanowire(NW)-induced cavity in a silicon planar photonic crystal(PPC)waveguide to improve the light–NW coupling.The integration of NW shifts the transmission band of the PPC waveguide into the mode gap of the bare waveguide,which gives rise to a microcavity located on the NW section.Resonant modes with𝑄factors exceeding 103 are obtained.Leveraging on the high density of the electric field in the microcavity,the light–NW interaction is enhanced strongly for efficient nonlinear frequency conversion.Second-harmonic generation and sum-frequency generation in the NW are realized with a continuous-wave pump laser in a power level of tens of microwatts,showing a cavity-enhancement factor of 112.The hybrid integration structure of NW-PPC waveguide and the self-formed microcavity not only opens a simple strategy to effectively enhance light–NW interactions,but also provides a compact platform to construct NW-based on-chip active devices.