Establishment and validation of a predictive model for peripherally inserted central catheter-related thrombosis in patients with liver cancer

BACKGROUND Peripherally inserted central catheters(PICCs)are commonly used in hospitalized patients with liver cancer for the administration of chemotherapy,nutrition,and other medications.However,PICC-related thrombosis is a serious complication that can lead to morbidity and mortality in this patient population.Several risk factors have been identified for the development of PICC-related thrombosis,including cancer type,stage,comorbidities,and catheter characteristics.Understanding these risk factors and developing a predictive model can help healthcare providers identify high-risk patients and implement preventive measures to reduce the incidence of thrombosis.AIM To analyze the influencing factors of PICC-related thrombosis in hospitalized patients with liver cancer,construct a predictive model,and validate it.METHODS Clinical data of hospitalized patients with liver cancer admitted from January 2020 to December 2023 were collected.Thirty-five cases of PICC-related thrombosis in hospitalized patients with liver cancer were collected,and 220 patients who underwent PICC placement during the same period but did not develop PICC-related thrombosis were randomly selected as controls.A total of 255 samples were collected and used as the training set,and 77 cases were collected as the validation set in a 7:3 ratio.General patient information,case data,catheterization data,coagulation indicators,and Autar Thrombosis Risk Assessment Scale scores were analyzed.Univariate and multivariate unconditional logistic regression analyses were performed on relevant factors,and the value of combined indicators in predicting PICC-related thrombosis in hospitalized patients with liver cancer was evaluated using receiver operating characteristic(ROC)curve analysis.RESULTS Univariate analysis showed statistically significant differences(P<0.05)in age,sex,Karnofsky performance status score(KPS),bedridden time,activities of daily living impairment,parenteral nutrition,catheter duration,distant metastasis,and bone marrow suppression between the thrombosis group and the non-thrombosis group.Other aspects had no statistically significant differences(P>0.05).Multivariate regression analysis showed that age≥60 years,KPS score≤50 points,parenteral nutrition,stage III to IV,distant metastasis,bone marrow suppression,and activities of daily living impairment were independent risk factors for PICC-related thrombosis in hospitalized patients with liver cancer(P<0.05).Catheter duration of 1-6 months and catheter duration>6 months were protective factors for PICC-related thrombosis(P<0.05).The predictive model for PICC-related thrombosis was obtained as follows:P predictive probability=[exp(Logit P)]/[1+exp(Logit P)],where Logit P=age×1.907+KPS score×2.045+parenteral nutrition×9.467+catheter duration×0.506+tumor-node-metastasis(TNM)staging×2.844+distant metastasis×2.065+bone marrow suppression×2.082+activities of daily living impairment×13.926.ROC curve analysis showed an area under the curve(AUC)of 0.827(95%CI:0.724-0.929,P<0.001),with a corresponding optimal cut-off value of 0.612,sensitivity of 0.755,and specificity of 0.857.Calibration curve analysis showed good consistency between the predicted occurrence of PICC-related thrombosis and actual occurrence(P>0.05).ROC analysis showed AUCs of 0.888 and 0.729 for the training and validation sets,respectively.CONCLUSION Age,KPS score,parenteral nutrition,TNM staging,distant metastasis,bone marrow suppression,and activities of daily living impairment are independent risk factors for PICC-related thrombosis in hospitalized patients with liver cancer,while catheter duration is a protective factor for the disease.The predictive model has an AUC of 0.827,indicating high predictive accuracy and clinical value.

Establishment of predictive models and determinants of preoperative gastric retention in endoscopic retrograde cholangiopancreatography

BACKGROUND Study on influencing factors of gastric retention before endoscopic retrograde cholangiopancreatography(ERCP)background:With the wide application of ERCP,the risk of preoperative gastric retention affects the smooth progress of the operation.The study found that female,biliary and pancreatic malignant tumor,digestive tract obstruction and other factors are closely related to gastric retention,so the establishment of predictive model is very important to reduce the risk of operation.METHODS A retrospective analysis was conducted on 190 patients admitted to our hospital for ERCP preparation between January 2020 and February 2024.Patient baseline clinical data were collected using an electronic medical record system.Patients were randomly matched in a 1:4 ratio with data from 190 patients during the same period to establish a validation group(n=38)and a modeling group(n=152).Patients in the modeling group were divided into the gastric retention group(n=52)and non-gastric retention group(n=100)based on whether gastric retention occurred preoperatively.General data of patients in the validation group and identify factors influencing preoperative gastric retention in ERCP patients.A predictive model for preoperative gastric retention in ERCP patients was constructed,and calibration curves were used for validation.The receiver operating characteristic(ROC)curve was analyzed to evaluate the predictive value of the model.RESULTS We found no statistically significant difference in general data between the validation group and modeling group(P>0.05).The comparison of age,body mass index,hypertension,and diabetes between the two groups showed no statistically significant difference(P>0.05).However,we noted statistically significant differences in gender,primary disease,jaundice,opioid use,and gastrointestinal obstruction between the two groups(P<0.05).Mul-tivariate logistic regression analysis showed that gender,primary disease,jaundice,opioid use,and gastrointestinal obstruction were independent factors influencing preoperative gastric retention in ERCP patients(P<0.05).The results of logistic regression analysis revealed that gender,primary disease,jaundice,opioid use,and gastroin-testinal obstruction were included in the predictive model for preoperative gastric retention in ERCP patients.The calibration curves in the training set and validation set showed a slope close to 1,indicating good consistency between the predicted risk and actual risk.The ROC analysis results showed that the area under the curve(AUC)of the predictive model for preoperative gastric retention in ERCP patients in the training set was 0.901 with a standard error of 0.023(95%CI:0.8264-0.9567),and the optimal cutoff value was 0.71,with a sensitivity of 87.5 and specificity of 84.2.In the validation set,the AUC of the predictive model was 0.842 with a standard error of 0.013(95%CI:0.8061-0.9216),and the optimal cutoff value was 0.56,with a sensitivity of 56.2 and specificity of 100.0.CONCLUSION Gender,primary disease,jaundice,opioid use,and gastrointestinal obstruction are factors influencing preoperative gastric retention in ERCP patients.A predictive model established based on these factors has high predictive value.

Physics package based on intracavity laser cooling ^(87)Rb atoms for space cold atom microwave clock

This article proposes a new physics package to enhance the frequency stability of the space cold atom clock with the advantages of a microgravity environment. Clock working processes, including atom cooling, atomic state preparation,microwave interrogation, and transition probability detection, are integrated into the cylindrical microwave cavity to achieve a high-performance and compact physics package for the space cold atom clock. We present the detailed design and ground-test results of the cold atom clock physics package in this article, which demonstrates a frequency stability of 1.2×10^(-12) τ^(-1/2) with a Ramsey linewidth of 12.5 Hz, and a better performance is predicted with a 1 Hz or a narrower Ramsey linewidth in microgravity environment. The miniaturized cold atom clock based on intracavity cooling has great potential for achieving space high-precision time-frequency reference in the future.

Prediction model establishment and validation for enteral nutrition aspiration during hospitalization in patients with acute pancreatitis

BACKGROUND Acute pancreatitis(AP)is a disease caused by abnormal activation of pancreatic enzymes and can lead to self-digestion of pancreatic tissues and dysfunction of other organs.Enteral nutrition plays a vital role in the treatment of AP because it can meet the nutritional needs of patients,promote the recovery of intestinal function,and maintain the barrier and immune functions of the intestine.However,the risk of aspiration during enteral nutrition is high;once aspiration occurs,it may cause serious complications,such as aspiration pneumonia,and suffocation,posing a threat to the patient’s life.This study aims to establish and validate a prediction model for enteral nutrition aspiration during hospitalization in patients with AP.AIM To establish and validate a predictive model for enteral nutrition aspiration during hospitalization in patients with AP.METHODS A retrospective review was conducted on 200 patients with AP admitted to Chengdu Shangjin Nanfu Hospital,West China Hospital of Sichuan University from January 2020 to February 2024.Clinical data were collected from the electronic medical record system.Patients were randomly divided into a validation group(n=40)and a modeling group(n=160)in a 1:4 ratio,matched with 200 patients from the same time period.The modeling group was further categorized into an aspiration group(n=25)and a non-aspiration group(n=175)based on the occurrence of enteral nutrition aspiration during hospitalization.Univariate and multivariate logistic regression analyses were performed to identify factors influencing enteral nutrition aspiration in patients with AP during hospitalization.A prediction model for enteral nutrition aspiration during hospitalization was constructed,and calibration curves were used for validation.Receiver operating characteristic curve analysis was conducted to evaluate the predictive value of the model.RESULTS There was no statistically significant difference in general data between the validation and modeling groups(P>0.05).The comparison of age,gender,body mass index,smoking history,hypertension history,and diabetes history showed no statistically significant difference between the two groups(P>0.05).However,patient position,consciousness status,nutritional risk,Acute Physiology and Chronic Health Evaluation(APACHE-II)score,and length of nasogastric tube placement showed statistically significant differences(P<0.05)between the two groups.Multivariate logistic regression analysis showed that patient position,consciousness status,nutritional risk,APACHE-II score,and length of nasogastric tube placement were independent factors influencing enteral nutrition aspiration in patients with AP during hospitalization(P<0.05).These factors were incorporated into the prediction model,which showed good consistency between the predicted and actual risks,as indicated by calibration curves with slopes close to 1 in the training and validation sets.Receiver operating characteristic analysis revealed an area under the curve(AUC)of 0.926(95%CI:0.8889-0.9675)in the training set.The optimal cutoff value is 0.73,with a sensitivity of 88.4 and specificity of 85.2.In the validation set,the AUC of the model for predicting enteral nutrition aspiration in patients with AP patients during hospitalization was 0.902,with a standard error of 0.040(95%CI:0.8284-0.9858),and the best cutoff value was 0.73,with a sensitivity of 91.9 and specificity of 81.8.CONCLUSION A prediction model for enteral nutrition aspiration during hospitalization in patients with AP was established and demonstrated high predictive value.Further clinical application of the model is warranted.

人参皂苷Rg3调控lncRNA-LINP1抑制胃癌细胞生长的作用机制

目的目前关于长链非编码RNA-LINP1(lncRNA-LINP1)对胃癌作用的具体机制鲜有报道。文中旨在探讨人参皂苷Rg3通过调控lncRNA-LINP1,从而抑制胃癌细胞生长的机制。方法将对数生长期的人胃癌SNU-1细胞分为:对照组、低剂量组、中等剂量组与高剂量组,分别加入0、0.03、0.06、0.09μmol/L人参皂苷Rg3处理。MTT法检测细胞增殖,流式细胞仪检测细胞凋亡,划痕实验检测细胞迁移,实时定量PCR检测lncRNA-LINP1的表达。结果低剂量组、中等剂量组和高剂量组lncRNA-LINP1的表达水平明显低于对照组(P<0.05),高剂量组lncRNA-LINP1的表达水平明显低于低剂量组组和中等剂量组(P<0.05)。处理后24 h、48 h、72 h,高剂量组癌细胞增殖能力最弱,增殖抑制率高于低剂量组和中等剂量组(P<0.05)。低剂量组、中等剂量组、高剂量组细胞凋亡率[(4.56±0.92)%、(8.77±0.98)%、(15.06±2.42)%]高于对照组[(2.43±0.74)%],差异有统计学意义(P<0.05);且随着人参皂苷Rg3浓度增加,细胞凋亡率上升(P<0.05)。结论人参皂苷Rg3能通过抑制lncRNA-LINP1的表达,从而抑制胃癌细胞的增殖与迁移,并促进其凋亡,且这种作用随着Rg3浓度的增加而增强,从而发挥抑癌作用。

Yield performance and optimal nitrogen and phosphorus application rates in wheat and faba bean intercropping

Yield performance in cereal and legume intercropping is related to nutrient management,however,the yield response of companion crops to nitrogen(N)input is inconclusive and only limited efforts have focused on rationed phosphorous(P)fertilization.In this study,two multi-year field experiments were implemented from 2014-2019 under identical conditions.Two factors in a randomized complete block design were adopted in both experiments.In field experiment 1,the two factors included three planting patterns(mono-cropped wheat(MW),mono-cropped faba bean(MF),and wheat and faba bean intercropping(W//F))and four N application rates(N0,0 kg N ha^(-1);N1,90 and 45 kg N ha^(-1) for wheat and faba beans,respectively;N2,180 and 90 kg N ha^(-1) for wheat and faba beans,respectively;and N3,270 and 135 kg N ha^(-1) for wheat and faba beans,respectively).In field experiment 2,the two factors included three P application rates(P0,0 kg P_(2)O_(5) ha^(-1);P1,45 kg P_(2)O_(5) ha^(-1);and P2,90 kg P_(2)O_(5) ha^(-1))and the same three planting patterns(MW,MF,and W//F).The yield performances of inter-and mono-cropped wheat and faba beans under different N and P application rates were analyzed and the optimal N and P rates for intercropped wheat(IW)and MW were estimated.The results revealed that intercropping favored wheat yield and was adverse to faba bean yield.Wheat yield increased by 18-26%,but faba bean yield decreased by 5-21% in W//F compared to MW and MF,respectively.The stimulated IW yield drove the yield advantage in W//F with an average land equivalent ratio(LER)of 1.12.N and P fertilization benefited IW yield,but reduced intercropped faba bean(IF)yield.Nevertheless,the partial LER of wheat(pLER_(wheat))decreased with increasing N application rates,and the partial LER of faba bean(pLER_(faba bean))decreased with increasing P application rates.Thus,LER decreased as N input increased and tended to decline as P rates increased.IW maintained a similar yield as MW,even under reduced 40-50% N fertilizer and 30-40% P fertilizer conditions.The estimated optimum N application rates for IW and MW were 150 and 168 kg ha^(-1),respectively,and 63 and 62 kg ha^(-1) for P_(2)O_(5),respectively.In conclusion,W//F exhibited yield advantages due to stimulated IW yield,but the intercropping yield benefit decreased as N and P inputs increased.Thus,it was concluded that modulated N and P rates could maximize the economic and ecological functions of intercropping.Based on the results,rates of 150 kg N ha^(-1) and 60 kg P_(2)O_(5) ha^(-1) are recommended for IW production in southwestern China and places with similar conditions.

MOBILITY EVALUATION AND INNOVATION OF WHEELED SPACE ROVER

The mission and function requirements of lunar rover are analyzed, based on virtual prototype technology, the mobility evaluation theory and method for wheeled space rover are proposed, which provide a new way to study the innovative design of lunar rover. Based on the above theoretical system, an innovative lunar rover suspension system, which adopts a two-crank-slider mechanism, is proposed, and its dynamics model is created. Adopting virtual prototype technology, the ground adaptability, over-obstacle ability and driving placidity of the rover are evaluated in the virtual prototype software ADAMS. The analysis results show that the rover provides a high degree of mobility.

Feasibility Analysis on the Integrated Application of Solar Energy, Biogas, Coal-fired Boiler and Radiant Floor Heating for Rural Residence

The feasibility of adopting a balanced energy mix mode (domestic solar energy, biogas, coal-fired boiler and radiant floor heating) was proposed. Taking a typical rural residence in Zhengzhou City for example, the study through theoretical analysis and calculation showed that such a balanced energy mix is an economic way and efficient in saving energy and reducing air pollution, and elaborated the theoretical feasibility of popularizing such a heat supply mode in rural areas.

认知行为干预对上消化道早癌行内镜下黏膜剥离术患者的效果研究

目的探讨基于人文关怀理念的认知行为干预对上消化道早癌患者疼痛、心理和康复效果的影响。方法选择196例上消化道早期癌症行内镜下黏膜剥离术(ESD)患者,随机分为对照组和观察组,每组98例。对照组给予上消化道早癌ESD知识宣教,观察组在此基础上给予基于人文关怀理念的认知行为干预。比较2组康复情况、疼痛视觉模拟评分法(VAS)评分、焦虑自评量表(SAS)评分、一般自我效能感量表(GSES)评分、术后并发症。结果观察组的术后肛门排气时间、术后首次排便时间和术后住院时间为(24.67±8.25)h、(43.90±10.27)h、(9.38±2.02)d,分别短于对照组的(27.83±9.40)h、(50.03±12.85)h、(10.26±2.37)d;手术24、48、72 h后观察组VAS评分为(2.63±0.67)、(1.84±0.52)、(1.33±0.38)分,分别低于对照组的(2.89±0.70)、(2.06±0.58)、(1.47±0.42)分;观察组干预后SAS评分为(38.73±7.40)分,低于对照组的(42.05±8.01)分;观察组干预后的GSES评分为(31.53±6.27)分,高于对照组的(29.28±5.96)分,差异均有统计学意义(P<0.05)。2组总并发症发生率比较,差异无统计学意义(P>0.05)。结论对上消化道早癌患者实施基于人文关怀理念的认知行为干预可减轻疼痛和焦虑情绪,促进患者快速康复。

Lyase Activities of Heterologous CpcS and CpcT for Phycocyanin Holo-β-subunit from Arthrospira platensis in Escherichia coli

Arthrospira platensis is an economically important cyanobacterium; and it has been used widely in food and pharmaceutical industries. The phycocyanin(PC) from A. platensis is extremely valuable in medicine and molecular biology due to its antioxidation and anti-tumoring activity and applicability as fluorescence protein tag. In present study, two recombinant plasmids, one contained the phycocyanobilin(PCB)-producing genes(hox1 and pcyA) while the other contained the phycobiliprotein gene(cpcB) and the lyase gene(either cpcS/U or cpcT), were constructed and synchronically transferred into E. coli in order to test the the activities of relevant lyases for catalysing PCB addition to CpcB during synthesizing fluorescent PC holo-β-subunit(β-PC) of A. platensis. As was evidenced by the fluorescence emitted at a peak specific for PC, CpcB was successfully synthesized in E. coli, to which co-expressed PCBs attached though at a relatively low efficiency. The results showed that the attachment of PCBs to CpcB were carried out mainly by co-expressed CpcS/U but CpcB also showed some autocatalytic activity. Currently, no CpcT activity was detected in this E. coli expression system. Further studies will be conducted to improve the efficiency of fluorescent PC synthesis in E. coli.

育苗容器对紫叶紫薇容器苗生长、开花及生理的影响

【目的】探讨育苗容器类型和规格对紫叶紫薇容器苗生长、开花及生理的影响,筛选出培育紫叶紫薇容器苗的适宜育苗容器,为高效培育紫薇容器苗提供理论依据。【方法】以紫叶紫薇优良新品种‘丹红紫叶’2年生苗木为研究材料,选用黑色塑料营养杯(C1)、白色无纺布美植袋(C2)、黑色控根容器(C3)3个类型以及16×16(D1)、21×21(D2)、25×25(D3)3种规格(直径×高,cm),组成9种容器组合处理,测定不同处理容器苗生长、开花及生理指标。【结果】(1)不同育苗容器处理对紫叶紫薇容器苗的生长、开花及生理指标均影响显著,同一容器类型苗木的生长、根系、生物量、花期、花径、花序、可溶性蛋白含量、可溶性糖含量、相对叶绿素含量、净光合速率、气孔导度、蒸腾速率等指标均随着育苗容器规格的增大而显著增加。(2)地径生长量、总根长、总根表面积、总根体积、根尖数、地上部干质量、地下部干质量、总干质量、花期均以C3D3处理最大,比最小的C1D1处理分别显著提高817.12%、108.12%、94.60%、75.66%、144.14%、135.67%、228.45%、164.65%、34.48%;苗高生长量、冠幅生长量、叶面积、花序长和宽均以C1D3处理最高,比最低的C1D1处理分别显著提高116.05%、81.39%、114.95%、70.44%和65.79%;相对叶绿素含量、水分利用效率均以C3D3处理最大,可溶性蛋白和可溶性糖含量、净光合速率、气孔导度均以C1D3处理最高;胞间CO_(2)浓度、水分利用效率在各处理之间无显著差异。(3)各处理隶属函数法综合评价得分排序为:C3D3>C1D3>C2D3>C3D2>C2D2>C1D2>C2D1>C3D1>C1D1。【结论】黑色控根容器在地径生长量、根系生长指标、生物量、花期和花径、叶绿素相对含量及净光合速率方面表现最佳;紫叶紫薇2年生苗的最适宜育苗容器是直径25 cm、高25 cm的黑色控根容器。

房角切开术围手术期前房出血及术后一过性眼压升高管理方案专家推荐意见

房角切开术(GT)是一种安全、有效的微创青光眼手术(MIGS),在我国已得到广泛应用,适用于治疗原发性开角型青光眼和中晚期原发性闭角型青光眼。尽管GT手术的安全性较高,但前房出血和一过性眼压升高仍然是GT术后常见的并发症。然而,在处理这类问题时,临床医生缺乏统一的标准化规范。这种情况不仅可能影响临床医生对手术效果的判断,还可能对手术预后产生不利影响。因此,有必要制定详细、完整的围手术期前房出血及术后一过性眼压升高管理方案,指导临床医生合理、规范地处理并发症,推动MIGS的进一步发展和完善。为此国内部分青光眼治疗专家及广东省医学会眼科学分会青光眼学组相关专家共同回顾既往文献,通过反复讨论,对GT围手术期前房出血和术后一过性眼压升高的管理方案达成一致性推荐意见,包括围手术期前房出血的定义、高危因素、转归,术前预防出血的方法、术中减少出血的方法、术后前房出血的管理,及一过性眼压升高的定义、发生原因、影响因素、处理及转归等方面,以供临床医生参考使用。

健康管理护理基本技术质量控制与评价指标体系的构建

目的:构建健康管理护理基本技术质量控制与评价指标体系,为健康管理护理基本技术规范化、同质化管理提供参考依据。方法:在三维质量结构理论基础上,采用文献检索法、研究小组讨论和德尔菲专家函询法,筛选指标并量化质量控制与评价的维度、条目及各级评价指标。结果:最终形成健康管理护理基本技术质量控制与评价指标体系,包括一级指标3项,二级指标10项,三级指标51项。2轮专家函询问卷有效应答率均为94.4%,函询专家的权威系数为0.879,第1、第2轮咨询的肯德尔和谐系数分别为0.210、0.199,均P<0.001。结论:本研究构建的健康管理护理基本技术质量控制与评价指标体系科学、有效、客观、可操作,对规范健康管理护理服务实践、培训和考核具有参考意义,也可为健康管理机构开展健康管理护理基本技术质量控制提供可借鉴的指标。

热液脉型萤石矿床隐伏矿体定位预测综合技术方法

萤石是国家战略性新兴产业发展中不可或缺的关键支撑原材料,被国际社会普遍列为“关键矿产”,随着萤石露头矿的发现殆尽,急需开展隐伏矿体的深部定位预测研究。文章简要论述了断裂构造控制的热液脉型萤石矿床地质特征、分带模式和成矿规律,评述了萤石找矿中常用的勘查技术方法。结合找矿标志和控矿要素分析,总结了隐伏-半隐伏萤石矿体定位预测的找矿模型,提出了“分带型”和“掩埋型”两种类型隐伏萤石矿体及相应的找矿技术方法组合。笔者建立了隐伏萤石矿体定位预测的地质-物探-化探-遥感综合找矿模型及其四步勘查技术流程,这对指导隐伏萤石矿床(体)的找矿勘查具有重要的理论和实践意义。

干旱胁迫对紫叶紫薇容器苗生长及生理的影响

为探究干旱胁迫对紫叶紫薇容器苗的生长及生理影响,以紫叶紫薇优良新品种‘丹红紫叶’2年生容器苗为研究对象,设计了5个干旱胁迫强度处理,测定不同干旱胁迫处理对容器苗生长及生理相关指标的影响。结果表明:干旱胁迫对紫叶紫薇容器苗的生长及生理的影响显著。随着干旱胁迫强度增加,紫叶紫薇容器苗叶片相对含水量、过氧化物酶活性、超氧化物歧化酶活性、可溶性蛋白含量、净光合速率、气孔导度、蒸腾速率总体上呈现降低趋势,重度干旱时这些指标分别比正常供水显著下降了21.45%、40.45%、31.92%、3.30%、81.25%、89.29%、87.17%,极重度干旱时达到最低值。可溶性糖含量、脯氨酸含量、丙二醛含量随着干旱胁迫程度增强而一直上升,重度干旱时分别比正常供水显著增加了122.92%、74.98%、288.34%,极重度干旱时达到最大值。随着干旱胁迫强度加重,过氧化氢酶活性、叶绿素相对含量、水分利用效率呈现先升高后降低的趋势,中度干旱时过氧化氢酶活性最大,叶绿素相对含量和水分利用效率则是轻度干旱最高,极重度干旱时最低。胞间CO_(2)浓度随着干旱胁迫加强而先降后升,正常供水的胞间CO_(2)浓度最高,中度干旱最低。紫叶紫薇容器苗具有抵御中度干旱的能力,当土壤相对含水量下降至30%~35%时应及时给苗木浇水灌溉。

梨火疫病抗性评价体系的建立及其种质资源抗性鉴定

【目的】利用梨幼果建立梨火疫病(Erwinia amylovora)抗性资源评价体系,筛选出对梨火疫病具有抗性的材料,为抗病育种提供技术支撑。【方法】以36个梨品种和41个库尔勒香梨杂交后代为材料,利用人工接种的方式对幼果期、膨大期和成熟期的果实进行接种试验,并根据接种后致病力的强弱,制定梨品种(种质)的抗性分级指标,综合评价77份种质资源的抗病水平。【结果】与梨果实膨大期和成熟期相比,接种幼果期果实更能准确评估梨品种(种质)的抗性水平;在接种24 h后,梨幼果开始显症;77个品种(种质)对梨火疫病的抗性水平差异显著,高感品种(种质)13个,感病品种(种质)11个,中感品种(种质)27个,抗病品种(种质)26个;供试品种(种质)对梨火疫病的抗性不高,其中只有33.77%的品种(种质)表现抗病性,66.23%的品种(种质)不同程度感病。【结论】本研究建立以梨果实的幼果期为接种时期,在接种24 h时开始观察发病情况的梨火疫病抗性资源评价体系;从供试品种(种质)筛选出的26份材料达到抗性水平,为培育新的抗性品种提供参考。

22种抗生素对梨火疫病菌的室内毒力测定及对花器安全性评价

【目的】筛选出抑制梨火疫病的药剂,为梨火疫病的绿色安全防控提供技术支持。【方法】采用抑菌圈法筛选22种抗生素,评价其在库尔勒香梨花器上的安全性。【结果】13种抗生素对梨火疫病菌有抑制作用,其中在抑菌圈直径达到9 mm时,氯霉素①、注射用头孢噻肟钠、注射用头孢曲松钠和诺氟沙星的药剂有效浓度由低至高是5.30、7.60、9.88、11.64 mg/L,使用同等剂量下4种药剂的抑制作用强于其它药剂;氯霉素①、注射用头孢噻肟钠、注射用头孢曲松钠、罗红霉素分散片、诺氟沙星对库尔勒香梨花器的危害较轻。【结论】氯霉素①、诺氟沙星、注射用头孢曲松钠和注射用头孢噻肟钠可在田间防治梨火疫病上应用。

医学生童年期创伤与心理健康:心理弹性的中介作用

目的探讨医学生童年期创伤与心理弹性、心理健康的关系。方法采用儿童期创伤问卷、心理弹性量表、症状自评量表对3888名医学生进行问卷调查。结果医学生童年期创伤发生率为30.8%,不同性别、是否独生子女、不同生源地、有无留守经历和心理治疗(咨询)求助史的医学生童年期创伤、心理弹性和SCL-90得分差异有统计学意义(t=2.33~6.96,P<0.05);童年期创伤与心理弹性得分呈负相关(r=-0.31,P<0.05),与SCL-90得分呈正相关(r=0.38,P<0.05),心理弹性在童年期创伤与心理健康之间有中介作用(β=0.10,P<0.05)。结论童年期创伤经历越多的医学生,心理弹性越弱,心理健康状况越差。医学生童年期创伤对心理健康有直接预测作用,且受心理弹性的中介效应调节,须重点关注农村地区、非独生子女、有留守和心理治疗(咨询)求助经历的医学生,提升其心理弹性水平,促进其心理健康。

淹水胁迫对紫薇苗生长及生理特性的影响

以紫薇优良新品种‘丹红紫叶’二年生苗为试材,采用套盆淹水方法,设计了5个淹水持续时间处理,研究不同淹水胁迫处理对紫薇苗生长及生理指标的影响,以期为紫薇苗培育及园林应用的水分管理提供参考依据。结果表明:紫薇能承受14 d的淹水,淹水21 d是紫薇忍受淹水胁迫持续时间的极限。随着淹水胁迫时间增长,紫薇苗的叶片相对含水量、过氧化物酶活性、超氧化物歧化酶活性、可溶性蛋白质含量、净光合作用速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、胞间CO_(2)浓度(Ci)均总体呈下降趋势,淹水21 d时分别比对照处理显著下降了24.29%、79.88%、18.66%、3.16%、80.45%、92.51%、93.10%、25.43%,淹水28 d时达到最低值;脯氨酸、丙二醛含量呈上升趋势,淹水21 d时分别比对照显著增加67.34%、360.54%,淹水28 d最大;过氧化氢酶活性呈先升后降的趋势,淹水21 d最大,比对照显著增加252.65%;可溶性糖含量呈先降后升再降的趋势,淹水21 d最大,比对照显著增加19.38%;淹水胁迫期间紫薇苗的叶绿素相对含量变化不明显;水分利用效率(WUE)呈起伏波动走势,对照最低,淹水21 d较高,比对照显著高184.00%。紫薇苗具有一定的耐涝性,淹水胁迫持续时间不宜超过14 d。

不同基质对‘丹红紫叶’紫薇容器苗开花和光合特性的影响

[目的]为探究不同育苗基质对‘丹红紫叶’紫薇容器苗开花及光合特性的影响,筛选出紫薇容器苗培育的适宜育苗基质,为紫薇容器苗高效培育提供理论指导。[方法]以‘丹红紫叶’紫薇2年生容器苗为研究对象,用圃地土、泥炭、珍珠岩、蛭石不同比例配制16种育苗基质处理,以圃地土为对照(CK)基质,测定不同处理对容器苗开花及光合特性的影响。[结果]不同育苗基质对‘丹红紫叶’紫薇容器苗的开花及光合特性影响显著,T11处理的开花指标和光合特性指标综合表现最好,花期、花径、花序长和宽分别比CK增加了23d、22.63%、26.40%和30.20%,叶绿素相对含量、净光合速率、蒸腾速率、气孔导度、水分利用效率分别比CK显著提高了8.88%、413.58%、115.20%、100.00%、138.46%,T11处理的胞间CO 2浓度最低,比CK显著降低29.27%。开花指标与光合特性指标的相关性分析表明,花序与净光合速率、水分利用效率显著正相关,与胞间CO_(2)浓度显著负相关。主成分分析的综合得分最高为T11处理,最低为CK,T11处理基质配方有利于促进‘丹红紫叶’紫薇容器苗开花,提高光合效率。[结论]圃地土30%+泥炭50%+蛭石10%+珍珠岩10%的基质是‘丹红紫叶’紫薇2年生容器苗培育的最适宜基质。