硼对铁焦微观结构的影响

为探究硼原子对铁物种在焦炭分子骨架中的分布和价态组成的影响及对铁焦微观结构和强度的促进机理,以添加不同质量分数的硼酸制备的复合铁焦为研究对象,通过光学显微镜、X射线光电子能谱仪、X射线衍射仪等仪器,对比分析了硼添加前后铁焦微晶结构、光学组织、气孔结构和显微强度的变化。结果表明:在硼添加量为0.2%时,所制备的铁焦的Mf+Mm+Mc+Fi结构的含量达到最大,为68.25%,各向同性结构的含量降低,光学组织指数(OTI)和显微强度(MSI)均达到最大,分别为138和49.3,气孔率下降到59%,孔壁厚度增大到20μm;而随着硼添加量的进一步增大,铁焦的OTI和MSI均呈现下降趋势,气孔率上升,孔壁厚度减小。添加适量的硼后,硼原子以层间插入物进入铁焦石墨晶格,从而导致铁焦的稠环增大,中等尺寸各相异性结构含量增加,可促进热解成焦过程中类似粗粒镶嵌等强度较高的显微组织的形成,增大铁焦的壁厚。并且,硼原子对铁焦骨架的掺杂所形成的BC3结构使得铁焦微晶的石墨化程度增强,从而有助于改善铁焦的显微结构强度,有利于增强其稳定性。

基于图像处理和模糊控制的絮凝剂智能投加系统设计

净水处理工艺中,混凝过程是一个大滞后、非线性的复杂系统。针对其特点并结合目前国内外加药控制研究现状,开发了一种基于絮凝体图像处理、模糊逻辑控制的前馈-串级智能加药系统。通过水样图像采集与处理提取絮凝体特征关键参数,计算絮凝体等效直径,建立投加模型确定絮凝剂投加量,再通过模糊PID控制及前馈补偿实现絮凝剂的全自动调节和精准投加。系统监控及性能分析显示,与传统手工投加对比,智能投加系统沉淀后出水浊度标准偏差降低27%,与设定值的相对误差控制在10%以内,絮凝剂的投加量节省11.04%,在絮凝剂投加量和处理效果上具有显著优势,表现出良好的可行性和推广潜力。

淮北1/3焦煤与不同地域同类炼焦煤的差异性研究

选取4种淮北典型1/3焦煤和4种不同地域同类1/3焦煤为研究对象,对比分析了不同煤样官能团结构、化学性质和工艺性质的差异。结果表明,4种淮北1/3焦煤煤样总体挥发分和硫分相对较低,灰分偏高,而灰成分中矿物质催化指数MCI相对较低,碱金属含量低;其中,许疃、杨柳和孙疃1/3焦煤的活惰比、b值和Y值相对较高,且煤样软化温度低,软固区间温度宽,最大流动度高于其它煤样,表明煤样胶质体的流动性和热稳定性较好,可以替代部分优质肥煤使用。与印尼1/3焦煤相比,国内7种1/3焦煤整体的芳香缩合度较高,变质程度高,煤中SiO_(2)含量较高,其中淮北煤样中的杨柳、孙疃1/3焦煤的羟基含量高,而芦岭、许疃1/3焦煤的SiO_(2)含量相对较高。

Effect of electrical parameters and slag system on macrostructure of electroslag ingot

To investigate the influence of electric parameters and slag system on the solidification quality of electroslag ingot during electroslag remelting,different power supply modes,current strengths and remelting slag systems were used to conduct electroslag remelting experiments on 304L austenitic stainless steel,and the macrostructure of electroslag ingots was analyzed.The results indicate that the depth of the metal pool decreases with the reduction of remelting frequency in the low frequency power supply mode.The effects of different power supply modes,such as low-frequency,direct current straight polarity(DCSP),and direct current reverse polarity(DCRP),on reducing the depth of the metal pool increase in that order.By reducing the remelting current strength in the same power supply mode,the depth of metal pool is reduced.When compared to the binary slag system of 70%CaF2+30%Al2O3,the ternary slag system of 60%CaF2+20%Al2O3+20%CaO is more effective in reducing the depth of the metal pool during remelting.Utilizing the 60%CaF2+20%Al2O3+20%CaO ternary slag system results in a shallower and flatter metal pool,with columnar crystal growth occurring closer to the axial crystal.This effect is observed for both low frequency and direct current(DC)power supply modes.

The History of Controlling and Treating Infectious Diseases in Ancient China

Infectious diseases are the common enemies of mankind.In the course of historical development,they persistently threaten human health and safety.Even today,despite the developments in medical science,we cannot escape the fear and suffering caused by infectious diseases.Whether in ancient or modern times,the source of infection,route of transmission,and a susceptible population are the three key conditions for the prevalence and spread of infectious diseases.All factors closely related to these three conditions can affect the prevalence of infectious diseases.China is one of the cradles of world civilization.The ancient people accumulated a great deal of experience and lessons in the long struggle against infectious diseases.In the face of the current threat posed by widespread infectious disease,it is imperative to review and summarize ancient Chinese ideas and health policies on epidemic prevention and control to inspire contemporary efforts in the prevention and control of infectious disease.The combination of prevention-oriented epidemic prevention ideology and traditional medicine provides valuable insights,especially for impoverished and medically underserved regions.

Facile Semiconductor p-n Homojunction Nanowires with Strategic p-Type Doping Engineering Combined with Surface Reconstruction for Biosensing Applications

Photosensors with versatile functionalities have emerged as a cornerstone for breakthroughs in the future optoelectronic systems across a wide range of applications.In particular,emerging photoelectrochemical(PEC)-type devices have recently attracted extensive interest in liquid-based biosensing applications due to their natural electrolyte-assisted operating characteristics.Herein,a PEC-type photosensor was carefully designed and constructed by employing gallium nitride(GaN)p-n homojunction semiconductor nanowires on silicon,with the p-GaN segment strategically doped and then decorated with cobalt-nickel oxide(CoNiO_(x)).Essentially,the p-n homojunction configuration with facile p-doping engineering improves carrier separation efficiency and facilitates carrier transfer to the nanowire surface,while CoNiO_(x)decoration further boosts PEC reaction activity and carrier dynamics at the nanowire/electrolyte interface.Consequently,the constructed photosensor achieves a high responsivity of 247.8 mA W^(-1)while simultaneously exhibiting excellent operating stability.Strikingly,based on the remarkable stability and high responsivity of the device,a glucose sensing system was established with a demonstration of glucose level determination in real human serum.This work offers a feasible and universal approach in the pursuit of high-performance bio-related sensing applications via a rational design of PEC devices in the form of nanostructured architecture with strategic doping engineering.

Antibody-platinum(IV)prodrugs conjugates for targeted treatment of cutaneous squamous cell carcinoma

Antibody-drug conjugates(ADCs)are a new type of targeting antibodies that conjugate with highly toxic anticancer drugs via chemical linkers to exert high specificity and efficient killing of tumor cells,thereby attracting considerable attention in precise oncology therapy.Cetuximab(Cet)is a typical antibody that offers the benefits of good targeting and safety for individuals with advanced and inoperable cutaneous squamous cell carcinoma(cSCC);however,its anti-tumor activity is limited to a single use.Cisplatin(CisPt)shows good curative effects;however,its adverse effects and non-tumor-targeting ability are major drawbacks.In this study,we designed and developed a new ADC based on a new cytotoxic platinum(IV)prodrug(C8Pt(IV))and Cet.The so-called antibody-platinum(IV)prodrugs conjugates,named Cet-C8Pt(IV),showed excellent tumor targeting in cSCC.Specifically,it accurately delivered C8Pt(IV)into tumor cells to exert the combined anti-tumor effect of Cet and CisPt.Herein,metabolomic analysis showed that Cet-C8Pt(IV)promoted cellular apoptosis and increased DNA damage in cSCC cells by affecting the vitamin B6 metabolic pathway in tumor cells,thereby further enhancing the tumor-killing ability and providing a new strategy for clinical cancer treatment using antibody-platinum(IV)prodrugs conjugates.

Beam oscillating parameters on pore inhibition,recrystallization and grain boundary characteristics of laser-arc hybrid welded AZ31 magnesium alloy

Oscillating laser-arc hybrid welding of AZ31B magnesium alloy was carried out,the effects of beam oscillation parameters on pore inhibition,microstructure,grain boundary characteristics and tensile properties were investigated.The results showed that the pore formation can be inhibited with oscillating frequency higher than 75 Hz and radius smaller than 0.5 mm.The columnar grains neighboring the fusion line can be broken by the beam oscillation behavior,while the grain growth was promoted with the increase of frequency or radius.It should be noted that the coincidence site lattice(CSL)boundaries were mainlyΣ13b andΣ29 boundaries,which were contributed by{10■2}tensile twins and{11■2}compression twins,respectively.The total fraction of CSL boundaries reached maximum at radius of 0.25 mm and frequency of 75 Hz,which was also confirmed as the optimized parameters.In this case,the elongation rate increased up to 13.2%,12.8%higher than that of the weld without beam oscillation.Finally,the pore formation and inhibition mechanisms were illustrated according to the state of melt flow and keyhole formation,the abnormal growth was discussed basing on secondary recrystallization,and the relationship among the pore formation,grain size,boundary characteristics and weld toughness were finally established.

γ-Aminobutyric acid alleviates litchi thaumatin-like protein-induced inflammation and reduces gut microbial translocation

Previous research reported litchi thaumatin-like protein(LcTLP)could lead to inflammation,which is a factor causing the adverse reactions after excessive intake of litchi.As a main amino acid in litchi pulp,γ-aminobutyric acid(GABA)was found with anti-inflammatory effect.Therefore,this study aimed to investigate the effects of GABA on LcTLP-induced inflammation through RAW264.7 macrophages and C57BL mice models.In vitro study showed GABA could effectively regulate the level of inflammatory cytokines(interleukin(IL)-1β,IL-6,IL-10,and prostaglandin E2)and Ca2+in cells,and inhibit the phosphorylation of p65,IκB,p38,c-Jun N-terminal kinase(JNK)and extracellular signal-regulated kinase(ERK).These results indicate GABA alleviated inflammation through nuclear factor-κB and mitogen-activated protein kinase pathway signaling pathways.In vivo experiment was performed to verify the anti-inflammatory effect of GABA,and the results demonstrated that GABA reduced the inflammation and oxidative stress in the liver of LcTLP-treated mice,as it down-regulated the pro-inflammatory cytokines,malondialdehyde,aspartate transferase,and alanine transaminase.The relative expression of phosphorylated p38,JNK and ERK in mice liver with GABA treatment were reduced to 65%,39%and 80%of the control group,respectively.Furthermore,GABA treatment enriched probiotic bacteria and decreased pathogenic bacteria in mice gut,which reveals GABA could effectively reduce the translocation of gut microbiota.

Coupling of BiOCl Ultrathin Nanosheets with Carbon Quantum Dots for Enhanced Photocatalytic Performance

Over the past few decades,photocatalysis technology has received extensive attention because of its potential to mitigate or solve energy and environmental pollution problems.Designing novel materials with outstanding photocatalytic activities has become a research hotspot in this field.In this study,we prepared a series of photocatalysts in which BiOCl nanosheets were modified with carbon quantum dots(CQDs)to form CQDs/BiOCl composites by using a simple solvothermal method.The photocatalytic performance of the resulting CQDs/BiOCl composite photocatalysts was assessed by rhodamine B and tetracycline degradation under visible-light irradiation.Compared with bare BiOCl,the photocatalytic activity of the CQDs/BiOCl composites was significantly enhanced,and the 5 wt%CQDs/BiOCl composite exhibited the highest photocatalytic activity with a degradation efficiency of 94.5%after 30 min of irradiation.Moreover,photocatalytic N_(2)reduction performance was significantly improved after introducing CQDs.The 5 wt%CQDs/BiOCl composite displayed the highest photocatalytic N_(2)reduction performance to yield NH_3(346.25μmol/(g h)),which is significantly higher than those of 3 wt%CQDs/BiOCl(256.04μmol/(g h)),7 wt%CQDs/BiOCl(254.07μmol/(g h)),and bare BiOCl(240.19μmol/(g h)).Our systematic characterizations revealed that the key role of CQDs in improving photocatalytic performance is due to their increased light harvesting capacity,remarkable electron transfer ability,and higher photocatalytic activity sites.

Microstructure homogeneity and mechanical properties of laser-arc hybrid welded AZ31B magnesium alloy

Laser-arc hybrid welding of AZ31B magnesium alloy was carried out,the effects of welding parameters on weld formation,microstructure homogeneity and mechanical properties were investigated.The results showed that laser-arc hybrid welding was beneficial to improve the weld formation of magnesium alloy by inhibiting the defect of undercut and pores.The weld microstructure was mainly columnar grains neighboring the fusion line and equiaxed grains at the weld center.It was interesting that the grain size at the upper arc zone was smaller than that at the lower laser zone,with the difference mainly affected by laser power rather than welding current and welding speed.The welding parameters were optimized as laser power of 3.5 kW,welding current of 100 A and welding speed of 1.5 m/min.In this case,the weld was free of undercut and pores,and the tensile strength and elongation rate reached 252 MPa and 11.2%,respectively.Finally,the microstructure homogeneity was illustrated according to the heat distribution,and the evolution law of tensile properties was discussed basing on the weld formation and microstructure characteristics.

A 9.5-kb deletion in the 1st intron of OsMADS51 enhances temperature sensitivity in rice

Temperature is an important environmental factor affecting heading date of rice.Despite its importance,genes responsible for temperature-sensitive heading in rice have remained elusive.Our previous study identified a quantitative trait locus qHd1 which advances heading date under high temperatures.A 9.5-kb insertion was found in the first intron of OsMADS51 in indica variety Zhenshan 97(ZS97).However,the function of this natural variant in controlling temperature sensitivity has not been verified.In this study,we used CRISPR/Cas9 to knock out the 9.5-kb insertion in ZS97.Experiments conducted under cotrolled conditions in phytotrons confirmed that deletion increased temperature sensitivity and advanced heading by downregulating the expression level of OsMADS51.One-hybrid assays in yeast,ChIP-quantitative polymerase chain reaction,electrophoretic mobility shift,and luciferase-based transient transactivation assays collectively confirmed that OsMADS51 affects heading date by regulation of heading date gene Ehd1.We further determined that the long non-coding RNA HEATINR is generated from the first intron of OsMADS51,offering an explanation for how the 9.5-kb insertion affects temperature sensitivity.We also found that OsMADS51 was strongly selected in early/late-season rice varieties in South China,possibly accounting for their strong temperature sensitivity.These insights not only advance our understanding of the molecular mechanisms underlying the temperature-responsive regulation of heading date in rice but also provide a valuable genetic target for molecular breeding.

Clinical Value of the Quantitative Flow Ratio to Predict Long-term Target Vessel Failure in Patients with In-stent Restenosis after Drug-coated Balloon Angioplasty

Objective The study sought to investigate the clinical predictive value of quantitative flow ratio(QFR)for the long-term target vessel failure(TVF)outcome in patients with in-stent restenosis(ISR)by using drug-coated balloon(DCB)treatment after a long-term follow-up.Methods This was a retrospective study.A total of 186 patients who underwent DCB angioplasty for ISR in two hospitals from March 2014 to September 2019 were enrolled.The QFR of the entire target vessel was measured offline.The primary endpoint was TVF,including target vessel-cardiac death(TV-CD),target vessel-myocardial infarction(TV-MI),and clinically driven-target vessel revascularization(CD-TVR).Results The follow-up time was 3.09±1.53 years,and 50 patients had TVF.The QFR immediately after percutaneous coronary intervention(PCI)was significantly lower in the TVF group than in the no-TVF group.Multivariable Cox regression analysis indicated that the QFR immediately after PCI was an excellent predictor for TVF after the long-term follow-up[hazard ratio(HR):5.15×10−5(6.13×10−8−0.043);P<0.01].Receiver-operating characteristic(ROC)curve analysis demonstrated that the optimal cut-off value of the QFR immediately after PCI for predicting the long-term TVF was 0.925(area under the curve:0.886,95%confidence interval:0.834–0.938;sensitivity:83.40%,specificity:88.00;P<0.01).In addition,QFR≤0.925 post-PCI was strongly correlated with the TVF,including TV-MI and CD-TVR(P<0.01).Conclusion The QFR immediately after PCI showed a high predictive value of TVF after a long-term follow-up in ISR patients who underwent DCB angioplasty.A lower QFR immediately after PCI was associated with a worse TVF outcome.

Chemokine-like factor 1 (CKLF1) is expressed in myocardial ischemia injury in vivo and in vitro

Introduction:Chemokine-like factor 1(CKLF1)is a chemokine that is overexpressed in several diseases.Our previousfindings revealed a significant increase in CKLF1 expression in the ischemic brain,suggesting its potential as a therapeutic target for ischemic stroke.Methods:In this study,we examined the expression dynamics of CKLF1 in both in vivo and in vitro models of ischemic cardiac injury.Myocardial infarction(MI)was induced in vivo by ligation of the left anterior descending artery(LAD)of the rat heart.The levels of CKLF1,Creatine Kinase MB Isoenzyme(CK-MB),and Lactate dehydrogenase(LDH)in the serum were detected using Enzyme-linked immunosorbent assay(ELISA).The expression of CKLF1 in the infarcted area was detected by immunohistochemistry,immunofluorescence,quantitative PCR(qPCR),and Western blotting(WB).H9C2 and AC16 cardiomyocytes cultured in vitro were subjected to oxygen and glucose deprivation(OGD).LDH was used to detect cell damage,and CKLF1 expression was detected by qPCR and WB.Results:CKLF1 mRNA and protein expression were significantly increased in h9c2 cells at 1.5 h and in AC16 cells at 4 h after OGD.The serum CK-MB in rats increased significantly on thefirst day after infarction,while the LDH concentration increased significantly on the third day after infarction.CKLF1 blood levels significantly increased on thefirst day following MI in rats.CKLF1 expression notably increased in the infarct area on days 1,3,and 7 post-MI.In MI tissue,CKLF1 colocalizes with cardiomyocytes,macrophages,and neutrophils.Conclusion:CKLF1 was substantially expressed during myocardial ischemia injury both in vivo and in vitro and was colocalized with macrophages and neutrophils,indicating that CKLF1 is expected to be a biomarker and a drug target for the treatment of myocardial infarction.

覆盖课堂内外的预防医学专业课程思政实践——以健康教育学为例

在“健康中国”的时代背景下,以健康教育学为例,探索在课堂内外开展课程思政的方法与途径。引导预防医学专业学生聚焦国家政策、关注公共健康、注重学以致用,使学生放眼全球卫生、服务地方民生、践行医学誓言;采用理论与实践相结合的方式,深入挖掘专业课中的思政元素,打造深度融合课程思政的,有深度、有广度、有温度的专业“金课”,为全面推进公共卫生与预防医学专业“课程思政”改革提供可借鉴的思路。

化工系统工程课程教学改革实践探索

针对化工系统工程的复杂性特点,将课程的主要教学内容梳理为三个主线:“三传一反”(质量、动量、能量的传递和化学反应);“三流一态”(质量流、能量流、信息流和最优态);“三化一效”(数字化、信息化、智能化和高效)。在教学实践中,从分子、设备和流程层次重点讲授这三条主线的物理意义及其相互关系,取得了良好的教学效果。

胆囊神经内分泌癌的影像表现与病理特征分析

背景胆囊神经内分泌癌在临床实践中较为罕见,国内外文献中大多为病例报道,其临床特点及影像学表现方面的研究总结较少.目的探讨胆囊神经内分泌癌的影像学及病理表现特点,提高对该病的认识.方法回顾性分析经术后病理证实的8例胆囊神经内分泌癌的临床资料、影像与病理表现.结果年龄35岁-66岁,平均55.5岁,女性7例,男性1例,肿瘤最大径约0.7 cm-11.6 cm.6例行电子计算机断层扫描检查,5例病灶呈软组织密度,1例呈稍低密度灶;增强呈轻-中度不均匀强化,3例可见胆囊壁增厚并强化.8例均行磁共振成像检查,呈稍长/长T1、等/长T2信号,增强扫描呈不均匀持续性强化,2例动脉期明显强化.5例有肝门部、十二指肠合并腹腔、腹膜后淋巴结转移;2例累及肝脏;4例有肝门区胆管受压;2例有胆总管受侵;1例合并胰腺转移.免疫组织化学染色显示8例嗜铬蛋白A(chromogranin,Cg A)、突触素(synaptophysin,Syn)均为阳性,5例细胞角蛋白(cytokeratins,CK)、神经细胞黏附分子(CD56)阳性,4例神经元特异性烯醇化酶(neuron-specific enolase,NSE)阳性,6例Ki-67在(20%)以上,其中4例Ki-67在(70%)以上,1例Ki-67(9%),1例Ki-67(12%).结论胆囊神经内分泌癌影像学表现为胆囊底体部的不规则软组织肿块,伴胆囊壁弥漫性增厚和完整的黏膜层,肿瘤恶性程度高,早期即可出现沿线淋巴管、血道转移,对于早期诊断和鉴别诊断有一定价值,确诊仍依靠病理学检查.

Amisulpride augmentation therapy improves cognitive performance and psychopathology in clozapine‑resistant treatment‑refractory schizophrenia:a 12‑week randomized,double‑blind,placebo‑controlled trial

Background:Although clozapine is an effective option for treatment-resistant schizophrenia(TRS),there are still 1/3 to 1/2 of TRS patients who do not respond to clozapine.The main purpose of this randomized,double-blind,placebocontrolled trial was to explore the amisulpride augmentation efficacy on the psychopathological symptoms and cognitive function of clozapine-resistant treatment-refractory schizophrenia(CTRS)patients.Methods:A total of 80 patients were recruited and randomly assigned to receive initial clozapine plus amisulpride(amisulpride group)or clozapine plus placebo(placebo group).Positive and Negative Syndrome Scale(PANSS),Scale for the Assessment of Negative Symptoms(SANS),Clinical Global Impression(CGI)scale scores,Repeatable Battery for the Assessment of Neuropsychological Status(RBANS),Treatment Emergent Symptom Scale(TESS),laboratory measurements,and electrocardiograms(ECG)were performed at baseline,week 6,and week 12.Results:Compared with the placebo group,amisulpride group had a lower PANSS total score,positive subscore,and general psychopathology subscore at week 6 and week 12(PBonferroni<0.01).Furthermore,compared with the placebo group,the amisulpride group showed an improved RBANS language score at week 12(PBonferroni<0.001).Amisulpride group had a higher treatment response rate(P=0.04),lower scores of CGI severity and CGI efficacy at week 6 and week 12 than placebo group(PBonferroni<0.05).There were no differences between the groups in body mass index(BMI),corrected QT(QTc)intervals,and laboratory measurements.This study demonstrates that amisulpride augmentation therapy can safely improve the psychiatric symptoms and cognitive performance of CTRS patients.

Dietary supplementation with xylooligosaccharides and exogenous enzyme improves milk production,energy utilization efficiency and reduces enteric methane emissions of Jersey cows

Background Sustainable strategies for enteric methane(CH_(4))mitigation of dairy cows have been extensively explored to improve production performance and alleviate environmental pressure.The present study aimed to investigate the effects of dietary xylooligosaccharides(XOS)and exogenous enzyme(EXE)supplementation on milk production,nutrient digestibility,enteric CH_(4) emissions,energy utilization efficiency of lactating Jersey dairy cows.Forty-eight lactating cows were randomly assigned to one of 4 treatments:(1)control diet(CON),(2)CON with 25 g/d XOS(XOS),(3)CON with 15 g/d EXE(EXE),and(4)CON with 25 g/d XOS and 15 g/d EXE(XOS+EXE).The 60-d experimental period consisted of a 14-d adaptation period and a 46-d sampling period.The enteric CO_(2)and CH_(4) emissions and O2 consumption were measured using two GreenFeed units,which were further used to determine the energy utilization efficiency of cows.Results Compared with CON,cows fed XOS,EXE or XOS+EXE significantly(P<0.05)increased milk yield,true protein and fat concentration,and energy-corrected milk yield(ECM)/DM intake,which could be reflected by the significant improvement(P<0.05)of dietary NDF and ADF digestibility.The results showed that dietary supplementation of XOS,EXE or XOS+EXE significantly(P<0.05)reduced CH_(4) emission,CH_(4)/milk yield,and CH_(4)/ECM.Furthermore,cows fed XOS demonstrated highest(P<0.05)metabolizable energy intake,milk energy output but lowest(P<0.05)of CH_(4) energy output and CH_(4) energy output as a proportion of gross energy intake compared with the remaining treatments.Conclusions Dietary supplementary of XOS,EXE or combination of XOS and EXE contributed to the improvement of lactation performance,nutrient digestibility,and energy utilization efficiency,as well as reduction of enteric CH_(4) emissions of lactating Jersey cows.This promising mitigation method may need further research to validate its long-term effect and mode of action for dairy cows.

Isolation of phloridzin-degrading,IAA-producing bacterium Ochrobactrum haematophilum and its effects on the apple replant soil environment

We isolated and identified a bacterium that could produce IAA and degrade phloridzin in the rhizosphere soil of healthy replanted apple(the rootstock is M9T337 and the scion is Yanfu 3),providing a theoretical basis for reducing the obstacles associated with apple replant disease(ARD).Isolates were screened using Salkowski colorimetry and screening medium for phloridzin.The isolate of interest(W6)was identified as Ochrobactrum haematophilum based on morphological analysis,physiological and biochemical tests,and 16S rDNA sequencing.In a laboratory experiment,W6 produced auxin and promoted the growth of Arabidopsis thaliana roots,and its degradation rate of 100 mg.L^(-1 )phloridzin was 62.0%.In a pot experiment,W6 significantly reduced the phenolic acid contents of replanted soil,lowered the abundance of the harmful fungus Fusarium solani,and increased soil enzyme activities,thereby improving the micro-ecological environment of replant soil.W6 increased the root antioxidant enzyme activity and leaf photosynthetic pigment content of replanted Malus hupehensis Rehd.seedlings,effectively alleviating the decrease in net photosynthetic rate,transpiration rate and stomatal conductance caused by ARD.In a field experiment,W6 also promoted the growth of replanted apple(the rootstock is M9T337 and the scion is Yanfu 3)saplings.Therefore,W6 can promote apple growth and degrade phenolic acids,and it can be used as an effective treatment for the reduction of ARD.