Establishment of a Multiplex Detection Method for Common Bacteria in Blood Based on Human Mannan-Binding Lectin Protein-Conjugated Magnetic Bead Enrichment Combined with Recombinase-Aided PCR Technology

Objective Recombinase-aided polymerase chain reaction(RAP)is a sensitive,single-tube,two-stage nucleic acid amplification method.This study aimed to develop an assay that can be used for the early diagnosis of three types of bacteremia caused by Staphylococcus aureus(SA),Pseudomonas aeruginosa(PA),and Acinetobacter baumannii(AB)in the bloodstream based on recombinant human mannanbinding lectin protein(M1 protein)-conjugated magnetic bead(M1 bead)enrichment of pathogens combined with RAP.Methods Recombinant plasmids were used to evaluate the assay sensitivity.Common blood influenza bacteria were used for the specific detection.Simulated and clinical plasma samples were enriched with M1 beads and then subjected to multiple recombinase-aided PCR(M-RAP)and quantitative PCR(qPCR)assays.Kappa analysis was used to evaluate the consistency between the two assays.Results The M-RAP method had sensitivity rates of 1,10,and 1 copies/μL for the detection of SA,PA,and AB plasmids,respectively,without cross-reaction to other bacterial species.The M-RAP assay obtained results for<10 CFU/mL pathogens in the blood within 4 h,with higher sensitivity than qPCR.M-RAP and qPCR for SA,PA,and AB yielded Kappa values of 0.839,0.815,and 0.856,respectively(P<0.05).Conclusion An M-RAP assay for SA,PA,and AB in blood samples utilizing M1 bead enrichment has been developed and can be potentially used for the early detection of bacteremia.

不同硝酸钾滴灌追肥施用量对烤烟产质量的影响

为明确滴灌水肥一体化方式下,烤烟适宜的硝酸钾滴灌追肥施用量,于2016年通过田间试验研究了4种(除对照外)硝酸钾滴灌追肥施用量(不减量、减量20%、减量40%和减量60%)对烟株生长发育、烟叶化学品质及烟叶产质量的影响。结果表明,与对照(不施肥)相比,不减量、减量20%、减量40%和减量60%处理烟叶产量分别提高了84.1%、65.0%、75.7%和65.4%,产值分别提高了76.4%、73.9%、82.6%和61.9%;硝酸钾滴灌追肥施用量对烟株最大叶长、最大叶宽和平均叶面积均无显著影响(P>0.05)。不同硝酸钾滴灌追肥施用量处理中,以减量40%和减量20%处理中上等烟比例最高,与不减量处理相比分别提高了11.7和9.7个百分点。与不减量处理相比,减量40%处理烟叶产值提高了3.5%,减量20%处理烟叶产值相当。可见,总施氮(N)量90 kg/hm^2条件下(基追比50%∶50%),硝酸钾滴灌追肥施用量宜减少20%~40%,有利于烤烟节肥提质增效。烤烟滴灌水肥一体化生产中适宜的追肥施用量仍需进一步研究和探讨。

Development of an Internally Controlled Reverse Transcription Recombinase-aided Amplification Assay for the Rapid and Visual Detection of West Nile Virus

West Nile virus(WNV)causes West Nile fever and West Nile encephalitis.Because infection by WNV creates serious public health problems,its simple,rapid,and visual detection is very important in clinical practice,especially in resource-limited laboratories.We have developed a rapid,specific,and highly sensitive internally controlled reverse transcription recombinase-aided amplification(RTRAA)assay to detect WNV,using both real-timefluoresce nee and the lateral flow dipstick(LFD)at39.0°C for 30 min.The analytical sensitivity of theRT-RAA assay was 10 plasmid copies and 1.6 pfu perreacti on with real-time fluoresce nee,and 1,000plasmid copies per reaction with the LFD.No crossreactionwith other control viruses was observed.Compared with the RT-qPCR assay,the RT-RAA assaydemonstrated 100%sensitivity and 100%specificityfor WNV.

Rapid Internal Control Reference Recombinase-Aided Amplification Assays for EBV and CMV Detection

Epstein-Barr virus(EBV)and cytomegalovirus(CMV),two of the most prevalent human herpesviruses,cause a wide spectrum of diseases and symptoms and are associated with serious health problem.In this study,we developed an internal control reference recombinase-aided amplification(ICR-RAA)assay for the rapid detection of EBV and CMV within 30 min.The assay had a sensitivity of 5 and 1 copies/test for EBV and CMV,respectively,with no cross reaction with other pathogens.In comparison with those of the commercial quantitative polymerase chain reaction(qPCR),the sensitivity of the EBV and CMV ICR-RAAs using extracted DNA was 93.33%and 84.84%,respectively;the specificity was 98.75%and 100.00%,respectively;and the Kappa values were 0.930 and 0.892(P<0.05),respectively.In comparison with those of qPCR,the sensitivity of the EBV and CMV ICR-RAAs using the DNA by thermal lysis was 72.22%and 80.00%,respectively;the specificity was 100.00%。

Y2O3对Ti-6Al-4V合金显微组织及力学性能的影响

本文以Ti-6Al-4V+x Y2O3(x=0,0.2%,0.4%,0.6%,0.8%)粉末为原料,采用放电等离子烧结(SPS)工艺制备出Ti-6Al-4V+x Y2O3合金,利用光学显微镜和透射电镜探究Y2O3含量对Ti-6Al-4V合金显微组织和性能的影响。结果表明,添加Y2O3后会细化晶粒,当Y2O3含量超过0.2%之后,随着Y2O3含量的增加晶粒尺寸会逐渐增大;加入Y2O3后可以有效改善Ti-6Al-4V的力学性能,添加0.6%Y2O3时力学性能最好,屈服强度970 MPa、最大抗压强度1 852 MPa、压缩应变31.4%,较未添加稀土的Ti-6Al-4V合金分别提高7.8%、14.1%、19.4%,致密度提高到99.28%;Y2O3主要是通过提高Ti-6Al-4V制品的密度和在合金中的钉扎作用来提高力学性能。