Immobilization and Properties of Polyphenol Oxidase

[Objectives]This study was conducted to investigate the effects of embedding conditions on activity and catalytic properties of immobilized polyphenol oxidase.[Methods]Polyphenol oxidase was immobilized in a polymer material by the embedding method,and the optimal immobilization conditions were obtained by single factor tests:CaCl_(2) concentration 2.0%,sodium alginate concentration 2.0%,immobilization time 2 h and mass ratio of enzyme to carrier 10 mg/100 g,under which the immobilized enzyme activity was 93.33 U/g.Under the above conditions,the properties of polyphenol oxidase immobilized by sodium alginate(A-PPO)and free polyphenol oxidase were studied.[Results]The thermostability of A-PPO was better than that of the free enzyme,but the pH stability of A-PPO was inhibited.The Michaelis constant K_(m) values of free polyphenol oxidase and A-PPO were 0.37 and 0.48 mmol/L,respectively,and the maximum reaction rate V_(max) values were 0.38 and 0.51 mmol/(L·g),respectively.[Conclusions]This study provides a theoretical basis for the study of the properties of polyphenol oxidase.

Preparation of multicolor carbon dots with thermally turn-on fluorescence for multidimensional information encryption

Carbon dots(CDs)with superior fluorescence properties have attracted a growing number of research interests in anti-counterfeiting.However,the preparation of CDs with thermally turn-on fluorescence and full-color-emitting in visible spectrum is still a big challenge due to the complicated reaction mechanism in the formation of CDs.Here,a simple precursor-oriented strategy for the preparation of multicolor CDs with heat-stimuli turn-on fluorescence is reported.Comprehensive experimental characterizations and theoretical calculations revealed that the emission wavelength of CDs can be readily tuned from 460 nm to 654 nm with selected precursors,which was ascribed to the extent of conjugated sp2-domains(core states)and the amount of oxygen-and nitrogen-containing groups bound to sp2-domains(surface states).After simply mixing two or three kinds of CDs,a full-color range of fluorescence emission was realized,and the CDs-based fluorescence inks were successfully fabricated.Particularly,all the printed patterns from the inkjet exhibited a thermal-induced enhancement in fluorescence.On this basis,combining CDs with heating-induced“turn-off”fluorescence materials can lead to multidimensional and multistage encryption.These results demonstrate that the thermochromic and photochromic CDs with much more enhanced security exhibit promising application in data storage and encryption.

Isolation and Sequence Analysis of NSP2, ORF3 and ORF5 of PRRSV XH-GD Strain from Guangdong Province

The diseased samples collected from Guangdong Province were inoculated to Marc-145 cells, PRRSV-specific cytopathogenic effects （CPE） such as cell aggregation, cell shrinkage and cell exfoliation were observed and a PRRSV strain XH-GD was obtained. By using primers designed in accordance with the pub- lished gene se^lences of PRRSV in GenBank, NSP2, ORF3 and ORF5 fragments were amplified by reverse transcription polymerase chain reaction and analyzed by sequence aligment. The results demonstrated that PRRSV strain XH-GD belonged to the North American genotype and the NSP2 gene contained discontinuous de- letions of 30 amino acids. NSP2, ORF3 and ORF5 genes of XH-GD shared 83.3% -98.9%, 88.6% -99.2% and 88.1% -99.2% nucleotide homology, and 76.8% -98.3%, 83.7% -98.8% and 88.1% -99.2% amino acid homology with HUB1, NX06, BJsy06, VR-2332, HB-1（sh）2002, HB-2（sh）2002, CH-1a and RespPRRS MLV, respectively; however, NSP2, ORb3 and ORF5 genes of XH-GD shared only 52.9%, 65.0% and 64. 3% nucleotide homology, and 31.3%, 57.5% and 58.9% amino acid homology with LV, respectively. Phylogenetic analysis revealed that XH-GD had a closer relationship with HUB1, NX06, BJsy06, VR-2332, HB-1 （sh） 2002, HB-2 （sh） 2002, CH-la and RespPRRS MLV strains compared with LV strain.

IQ不平衡下全双工非线性自干扰频域对消

在全双工自干扰信道反射径较多的情况下,针对已有时域自干扰对消方案复杂度高的问题,提出了一种低复杂度的频域自干扰对消方案.该方案以全双工零中频架构为基础,综合考虑了IQ不平衡以及功放非线性对自干扰重建模型的影响,优化了已有频域自干扰重建模型的准确度.在此基础上,利用正交化辅助的连续干扰对消技术实现了低复杂度的自干扰消除.仿真分析表明,所提方案相比已有的基于RLS算法的频域自干扰对消方案,能够在存在IQ不平衡以及功放非线性的情况下实现几乎相同的自干扰对消性能,但是降低了68.75%的复杂度.

Engineering FeS_(2) nanoparticles on tubular g-C_(3)N_(4) for photo-Fenton treatment of paint wastewater

An efficient photo-Fenton catalyst(Fe S_(2)@HTCN)was designed by maximizing the synergistic effect of Fe S_(2)nanoparticles and hollow tubular g-C_(3)N_(4)(HTCN).Molecule self-assembly and molten salts-assisted calcination were used to engineering the hollow structured g-C_(3)N_(4)before anchoring Fe S_(2)nanoparticles on the walls of HTCN via reflux method.Compared to bulk g-C_(3)N_(4),the unique structure of HTCN and heterojunction in the composite endowed FeS_(2)@HTCN with more active sites and abundant channels for electron transfer and charge separation.The enriched electrons can improve the Fe^(3+) recycling and boost Fe^(2+) catalyzed ^(·)OH production via H_(2)O_(2).As-prepared photo-Fenton catalyst was successfully applied to the treatment of industrial paint wastewater.The paint wastewater with its COD as high as 8200 mg/L can be effectively degraded with 0.2 mol/L H_(2)O_(2)in 90 min under visible light irradiation.The photoFenton system was further evaluated according to the process stability and economic benefit,proving that the strategy presented in this work would be applicable to the treatment of real wastewater.