包头市小学生近视现况调查及相关因素分析

目的:调查包头市小学生近视现状并分析影响其近视相关因素,为教育卫生等部门近视防控提供数据支撑和理论依据。方法:采取随机整群抽样方法,2019-01/11调查包头市市区及牧区共26所小学中7~14岁学生视力情况,并发放近视相关因素调查问卷2000份,最终形成有效问卷1630份,建立近视数据库,进行统计学分析。结果:受调查学生31080人中近视人数共14845人,近视率为47.8%(14845/31080)。其中男生近视率44.3%(6912/15609),女生近视率51.3%(7933/15471)。市区近视率50.4%(9310/18489),牧区的近视率44.0%(5535/12591),汉族近视率48.0%(13185/27442),蒙古族近视率44.6%(1149/2576),其他民族近视率48.1%(511/1062),差异均有统计学意义(P<0.05)。11、12、13、14岁市区小学生近视率分别为51.9%(1333/2568)、62.8%(1671/2662)、72.0%(3415/4740)、45.4%(704/1551);牧区小学生近视率分别为46.5%(938/2019)、58.0%(1089/1877)、68.3%(1557/2279)、36.2%(338/934);11~14岁市区小学生近视率均高于牧区(P<0.05)。其中做眼保健操、喜食蔬菜水果为保护因素,地区、年级、趴着读书、弱光下读写或使用电子产品、父母近视、父亲文化程度均为近视危险因素。结论:包头小学生近视患病率处于较高水平,随年龄增加,近视患病率升高,多种因素与小学生近视相关,提醒家长及教育部门进行相关干预。

The mechanism of microwave rock breaking and its potential application to rock-breaking technology in drilling

The exploration and development of oil and gas resources have shifted from shallow to deep and ultradeep.The difficulty of rock breaking has also increased,introducing new challenges to traditional rock-breaking technology.Hence,there is an urgent need to develop new rock-breaking technologies to improve the development efficiency of deep oil and gas resources.Therefore,this study focused on the new microwave rock-breaking technology and conducted experimental and numerical simulation research on typical deep,hard rock granite.The research results showed that granite in the microwave field exhibited high-temperature melting and fracture,and the highest temperature could reach 550°C.Under the irradiation of circulating microwaves,a minimum irradiation time threshold of 3 min was needed to cause irreversible damage to the rock.The numerical simulation results showed that the interaction of thermal stress and in situ stress would cause the inside of the rock stratum to separate into a disturbed deterioration area,disturbed unloading area and initial stress area.These results are expected to provide the necessary technical guidance and theoretical support for the research and development of high-efficiency rock-breaking drilling for deep hard rock.

Transient gene expression in western white pine using agroinfiltration

A method for transient gene expression was developed for western white pine(WWP,Pinus monticola Dougl.ex D.Don)using reporter gene uidA encodingβ-glucuronidase(GUS).GUS was transiently expressed in cross sections of primary and secondary needles,cotyledons,and current and second year stems of WWP via vacuum-infiltration with Agrobacterium tumefaciens.Histochemical assays of cross sections of secondary needles showed stronger blue color indicating GUS expression at day 1 and 2 than on other days post agroinfiltration(dpa).GUS activity expressed inside WWP cells was confirmed using light microscopy.In fluorometric assays,GUS expression was high at 1 dpa and lasted until 4 dpa in detached secondary needles,while similarly high expression levels only lasted until 2 dpa in attached secondary needles then dropped significantly.Although the length of GUS-staining zones varied among different WWP organs and between growth and dormant seasons,all tested WWP tissues using the protocol had high levels of transient GUS expression.Thus,heterologous candidate genes or endogenous silencing can be expressed in various WWP tissues or organs using this agroinfiltration approach.The current protocol for efficient transient gene expression will aid functional genomics study of WWP and its pathogens and related conifer species.

Kinetic Characterization of Tyrosinase-catalyzed Oxidation of Four Polyphenols

Phenolic compounds such as chlorogenic acid,cryptochlorogenic acid,neochlorogenic acid and caffeic acid are widely distributed in fruits,vegetables and traditional Chinese medicines with a wide range of biological activities.Tyrosinase plays a critical role in the food industry,but recent studies have proposed unexplored aspects of clinical application.Tyrosinase-catalyzed oxidation of four polyphenols as well as its underlying mechanism remains unclear.In the current work,we investigated the kinetic properties of tyrosinase-catalyzed oxidation of the four polyphenols of interest.To measure the unstable o-quinone products,an analytical method using 3-methyl-2-benzothiazolinone hydrazone(MBTH)was established.The optimal incubation time,buffer pH,temperature and enzyme concentration for the enzyme activity in the presence of each polyphenol of interest were investigated.Under the final optimized conditions,the kinetics and substrate specificity of four polyphenols were examined.K inetic data showed that tyrosinase had the greatest substrate affinity to chlorogenic acid compared with its isomers and caffeic acid.The catalytic efficiency with chlorogenic acid was 8-to 15-fold higher than that with the other 3 polyphenols.Molecular docking study demonstrated that the tight binding of chlorogenic acid at the peripheral site should be the major reason for the specificity to chlorogenic acid.In light of this,the rational design of high-affinity inhibitors against tyrosinase may focus on the binding of both the Cu site and peripheral site.This study will supply a basis for the selection of phenolic acids in food industry and health carc.

Prognostic value of preoperative enhanced computed tomography as a quantitative imaging biomarker in pancreatic cancer

BACKGROUND Pancreatic ductal adenocarcinoma(PDAC)is one of the most lethal malignancies with high mortality and short survival time.Computed tomography(CT)plays an important role in the diagnosis,staging and treatment of pancreatic tumour.Pancreatic cancer generally shows a low enhancement pattern compared with normal pancreatic tissue.AIM To analyse whether preoperative enhanced CT could be used to predict postoperative overall survival in patients with PDAC.METHODS Sixty-seven patients with PDAC undergoing pancreatic resection were enrolled retrospectively.All patients underwent preoperative unenhanced and enhanced CT examination,the CT values of which were measured.The ratio of the preoperative CT value increase from the nonenhancement phase to the portal venous phase between pancreatic tumour and normal pancreatic tissue was calculated.The cut-off value of ratios was obtained by the receiver operating characteristic(ROC)curve of the tumour relative enhancement ratio(TRER),according to which patients were divided into low-and high-enhancement groups.Univariate and multivariate analyses were performed using Cox regression based on TRER grouping.Finally,the correlation between TRER and clinicopathological characteristics was analysed.RESULTS The area under the curve of the ROC curve was 0.768(P<0.05),and the cut-off value of the ROC curve was calculated as 0.7.TRER≤0.7 was defined as the low-enhancement group,and TRER>0.7 was defined as the high-enhancement group.According to the TRER grouping,the Kaplan-Meier survival curve analysis results showed that the median survival(10.0 mo)with TRER≤0.7 was significantly shorter than that(22.0 mo)with TRER>0.7(P<0.05).In the univariate and multivariate analyses,the prognosis of patients with TRER≤0.7 was significantly worse than that of patients with TRER>0.7(P<0.05).Our results demonstrated that patients in the low TRER group were more likely to have higher American Joint Committee on Cancer stage,tumour stage and lymph node stage(all P<0.05),and TRER was significantly negatively correlated with tumour size(P<0.05).CONCLUSION TRER≤0.7 in patients with PDAC may represent a tumour with higher clinical stage and result in a shorter overall survival.

Erratum to:Kinetic Characterization of Tyrosinase-catalyzed Oxidation of Four Polyphenols

The article“Kinetic Characterization of Tyrosinase-catalyzed Oxidation of Four Polyphenols”,written by Wan-yu LIU,Cong-ming ZOU,Jian-hua HU,Zi-jun XU,Lu-qin SI,Jun-jun LIU,Jian-geng HUANG,was originally published electronically on the publisher’s internet portal on May 2020 without open access.With the author(s)’decision to opt for Open Choice,the copyright of the article is changed to©The Author(s)2020 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License(https://creativecommons.org/licenses/by/4.0/),which permits use,sharing,adaptation,distribution and reproduction in any medium or format,as long as you give appropriate credit to the original author(s)and the source,provide a link to the Creative Commons license,and indicate if changes were made.