第55届国际化学奥林匹克试题(实验部分)

实验1:漂白剂——一种能改变物质颜色的试剂实验步骤Bleach:漂白剂;p-methoxyacetophenone:对甲氧基苯乙酮;major product:主产物产物A的制备1.打开磁力搅拌器开始加热。为了将水浴温度加热到70–80℃,需要将控制旋钮设置在100℃和150℃之间。搅拌水浴。可以将温度计夹在支架上,监控水浴温度。2.在水浴加热的同时,用小镍勺从标记为“SM-A”的小样品瓶中取少量对甲氧基苯乙酮,将其加入到标记为“TLC-SM”的小样品瓶中,放置在一边,以供后续进行薄层色谱(TLC)分析使用(待稍后进行)。

VSe_(2)/V_(2)C heterocatalyst with built-in electric field for efficient lithium-sulfur batteries:Remedies polysulfide shuttle and conversion kinetics

Lithium sulfur(Li-S)battery is a kind of burgeoning energy storage system with high energy density.However,the electrolyte-soluble intermediate lithium polysulfides(Li PSs)undergo notorious shuttle effect,which seriously hinders the commercialization of Li-S batteries.Herein,a unique VSe_(2)/V_(2)C heterostructure with local built-in electric field was rationally engineered from V_(2)C parent via a facile thermal selenization process.It exquisitely synergizes the strong affinity of V_(2)C with the effective electrocatalytic activity of VSe_(2).More importantly,the local built-in electric field at the heterointerface can sufficiently promote the electron/ion transport ability and eventually boost the conversion kinetics of sulfur species.The Li-S battery equipped with VSe_(2)/V_(2)C-CNTs-PP separator achieved an outstanding initial specific capacity of 1439.1 m A h g^(-1)with a high capacity retention of 73%after 100 cycles at0.1 C.More impressively,a wonderful capacity of 571.6 mA h g^(-1)was effectively maintained after 600cycles at 2 C with a capacity decay rate of 0.07%.Even under a sulfur loading of 4.8 mg cm^(-2),areal capacity still can be up to 5.6 m A h cm^(-2).In-situ Raman tests explicitly illustrate the effectiveness of VSe_(2)/V_(2)C-CNTs modifier in restricting Li PSs shuttle.Combined with density functional theory calculations,the underlying mechanism of VSe_(2)/V_(2)C heterostructure for remedying Li PSs shuttling and conversion kinetics was deciphered.The strategy of constructing VSe_(2)/V_(2)C heterocatalyst in this work proposes a universal protocol to design metal selenide-based separator modifier for Li-S battery.Besides,it opens an efficient avenue for the separator engineering of Li-S batteries.

《无机化学》教材编写的实践与思考

结合教材修订的时代背景,回顾总结了吉林大学等三校编写的各版次《无机化学》编写的背景、特色和主要修订内容,提出教材内容必须紧扣教学大纲要求,注意与高中化学课程的衔接,知识讲授上要照顾到大一学生的知识基础,始终保持可读性、可讲授性的教材建设理念,并对新时期新版《无机化学》教材修订进行了展望,以期能为“互联网+”时代的高校无机化学教材建设提供一定的参考。

第55届国际化学奥林匹克试题(理论部分)

第1题分子成像分子成像是医学诊断的有力工具。作为同位素^(99g)Tc(g=基态)的核异构体,^(99m)Tc(m=亚稳态)具有良好的辐射特性(γ辐射体,t_(1/2)=6.015 h),可用于成像。^(99m)Tc在锝发生器中通过母核的β-衰变得到,以^(99m)Tc-高锝酸盐[^(99m)TcO_(4)]−形式存在。

基于MOOC的“无机化学Ⅱ”课程在线教学的探索与实践

在抗击新冠肺炎疫情期间,吉林大学无机化学教学团队依托“无机元素化学”MOOC,以超星学习通平台为载体,QQ学习群为辅助,开展以学生为中心的“无机化学Ⅱ”课程的在线教学。通过学习通平台的大数据支持和互动交流版块,对学生“课前–课中–课后”三个学习环节的学习情况进行实时跟踪和分析,实现教师和学生的深度互动,有效完成教与学。

Study on Fungi Belonging to Fusarium Link in Ningxia Hui Autonomous Region

[Objective]This paper was to identify fungi belonging to Fusarium Link. [Method] The fungal species, distribution and the diseases caused by Fusarium Link in Ningxia Hui Autonomous Region were determined by the methods of field investigation, collection, isolated culture and identification. [ Result] Nine species of fungi belonging to Fusarium Link were identified, including F. avenaceum, F. concolor, F. culmorum, F. graminearum, F. moniliforme, F. nivale, F. oxysporum, F. solani, and one unnamed species. They were distributed throughout Ningxia Hui Autonomous Region and caused more than 30 kinds of plant diseases. [ Conclusion] Fusarium Link had many species in Ningxia Hui Autonomous Region without regional features, and all of them were plant pathogens.

Interpolation Fitting Algorithm in Time-Space Domain of Differential Barometric Altimetry

In order to overcome the limitations of a unitary reference station in mobile communication positioning network differential barometric altimetry(DBA)and broaden the action scope of the reference station and improve positioning accuracy of elevation,an integrated interpolation algorithm model based on generalized extended approximation(GEA)algorithm and Kriging interpolation in time-space domain of reference station is proposed.In the time domain,barometric measured data is considered the maximum value estimated by bilateral extension to avoid wrong direction of estimation,which is approaching true value.In the spatial domain,barometric relevance among multiple reference stations is utilized,the weighted coefficients of multiple reference stations is calculated by the integrated algorithm model based on the GEA algorithm and Kriging interpolation.The impact of each reference station to the measured station is quantified,so that a virtual reference station is constructed,which can overcome the limitation of barometric correction by a unitary reference station.In addition,the measurement error due to irregular change in atmospheric pressure will be eliminated.

客船生活供水系统计算方法研究

解析了现有的轮机手册、ISO标准计算方法如管径计算、压力水柜容积计算等对于应用于客船的局限性。提出了新的国外陆用的计算方法,并分析其在船舶供水系统计算的适用性。

Identification of a major QTL for Hessian fly resistance in wheat cultivar‘Chokwang’

The Hessian fly(HF,Mayetiola destructor)is one of the destructive pests of wheat(Triticum aestivum L.)worldwide.Resistant cultivars can effectively minimize wheat damage due to this insect pest.To identify new quantitative trait loci(QTL)for HF resistance,a population of recombinant inbred lines(RILs)was developed from a cross between the HF-resistant wheat cultivar‘Chokwang’and susceptible wheat‘Ning 7840’,and phenotyped for responses to HF attack.A linkage map was constructed using 1147 single nucleotide polymorphism(SNP)markers generated from genotyping-by-sequencing(GBS).One major QTL,QHf.hwwg-6 BS,for HF-resistance was identified on chromosome arm 6 BS,which explained up to84.0%of the phenotypic variation and was contributed by Chokwang.Two RILs showed recombination in the candidate interval of QHf.hwwg-6 BS,which delimited QHf.hwwg-6 BS to a 4.75 Mb physical interval between 6,028,601 bp and 10,779,424 bp on chromosome arm 6 BS of IWGSC Chinese Spring reference genome Ref Seq v2.0.Seven GBS-SNPs in the candidate interval were converted into Kompetitive allele specific polymerase chain reaction(KASP)markers.Two of them,KASP-6 B112698 and KASP-6 B7901215,were validated in a U.S.winter wheat panel.KASP-6 B112698 was nearly diagnostic,thus can be used to screen QHf.hwwg-6 BS and pyramid it with other resistance genes in breeding programs.

Development of diagnostic markers for a wheat leaf rust resistance gene Lr42 using RNA-sequencing

Wheat leaf rust is a prevalent foliar disease in wheat worldwide. Growing resistant cultivars is an effective strategy to minimize the impact of leaf rust on yield and grain quality. Lr42 is a leaf rust resistance gene identified from Aegilops tauschii and is still effective against current predominant leaf rust races in the United States and many other countries. In this study, we developed diagnostic DNA markers for Lr42 using the sequence polymorphisms of a differentially expressed gene(TaRPM1) encoding a putative NBARC protein in the Lr42 candidate region identified by RNA-sequencing of two near-isogenic lines contrasting in Lr42 alleles. Markers were designed based on a deletion mutation and a single nucleotide polymorphism(SNP) in the gene. Haplotype analyses of the newly developed markers in the three diversity panels demonstrated that they are diagnostic for Lr42, and superior to previously used markers in selection accuracy. These markers have the advantages of low cost and easy assay, and they are suitable for marker-assisted selection in breeding programs with either high-or low-throughput marker screening facilities.

崇文门税关的兴衰演变

熟悉北京的人都知道,北京有个崇文门,周边是颇具现代化的繁华都市街区,但鲜为人知的是,在明初,这里曾经设立了一个著名的税收机构——崇文门税关,它存在了500余年,历经辉煌。如今,我们只能从零星的档案资料、文献中解读信息,再现其辉煌的历史。明清至民国的档案资料中,述及崇文门税关的多为一些告示、奏折、税则条文、实录、会典以及正史《食货志》的相关记载。

Occurrence of No.12 lymph node micrometastasis in gastric cancer and its effect on clinicopathological parameters and prognosis

Objective This study aimed to investigate the occurrence of No.12 lymph node micrometastasis in patients with gastric cancer and its relationship with clinicopathological parameters and prognosis.Methods A cohort of 160 gastric cancer patients who underwent gastrectomy and lymph node dissection were selected as the research subjects.The immunohistochemical method was used to detect the micrometastasis of No.12 lymph node sections with negative routine pathological detection.At the same time,the clinical data of patients were collected and followed up to analyze the clinical significance of No.12 lymph node micrometastasis.Results A total of 370 No.12 lymph nodes were detected in 160 surgical specimens.Among 160 patients,27 patients were found to be positive for No.12 lymph nodes during routine pathological examination,with a positive rate of 16.8%.A total of 308 lymph nodes from 133 patients with negative routine pathological examinations were stained by immunohistochemistry.A total of 17 lymph nodes from 10 patients were found to be positive.The results showed that 37 of the 160 patients had No.12 lymph node metastasis,and the positive rate was 23.1%,which was 6.3%higher than that of routine pathological examination.Logistic multivariate analyses showed that the depth of invasion,lymph node metastasis in other groups,and clinical stage were independent risk factors for No.12 lymph node metastasis.The average follow-up time was 79.3 months,and the overall median survival time was 47.9 months.The survival time of the No.12 lymph node-negative group was 67.3±2.5Âmonths,the median survival time was 73.2 months;the survival time of the No.12 lymph node-positive group was(28.4±5.4)months,and the median survival time was 31.3 months.The survival time of the No.12 lymph node-negative group was significantly longer than that of the positive group(χ^(2)=12.75,P=0.000).Conclusion No.12 lymph node micrometastasis is a signal affecting the prognosis of patients with gastric cancer.Standardized dissection of No.12 lymph nodes is recommended for patients with gastric cancer who can undergo radical resection.

Epigenetic silencing of BEND4,a novel DNA damage repair gene,is a synthetic lethal marker for ATM inhibitor in pancreatic cancer

Synthetic lethality is a novel model for cancer therapy.To understand the function and mechanism of BEN domain-containing protein 4(BEND4)in pancreatic cancer,eight cell lines and a total of 492 cases of pancreatic neoplasia samples were included in this study.Methylation-specific polymerase chain reaction,CRISPR/Cas9,immunoprecipitation assay,comet assay,and xenograft mouse model were used.BEND4 is a new member of the BEN domain family.The expression of BEND4 is regulated by promoter region methylation.It is methylated in 58.1%(176/303)of pancreatic ductal adenocarcinoma(PDAC),33.3%(14/42)of intraductal papillary mucinous neoplasm,31.0%(13/42)of pancreatic neuroendocrine tumor,14.3%(3/21)of mucinous cystic neoplasm,4.3%(2/47)of solid pseudopapillary neoplasm,and 2.7%(1/37)of serous cystic neoplasm.BEND4 methylation is significantly associated with late-onset PDAC(>50 years,P<0.01)and tumor differentiation(P<0.0001),and methylation of BEND4 is an independent poor prognostic marker(P<0.01)in PDAC.Furthermore,BEND4 plays tumor-suppressive roles in vitro and in vivo.Mechanistically,BEND4 involves non-homologous end joining signaling by interacting with Ku80 and promotes DNA damage repair.Loss of BEND4 increased the sensitivity of PDAC cells to ATM inhibitor.Collectively,the present study revealed an uncharacterized tumor suppressor BEND4 and indicated that methylation of BEND4 may serve as a potential synthetic lethal marker for ATM inhibitor in PDAC treatment.

Modularly designed peptide-based nanomedicine inhibits angiogenesis to enhance chemotherapy for post-surgical recurrence of esophageal squamous cell carcinomas

Traditional surgical treatment is difficult to thoroughly remove esophageal squamous cell carcinomas(ESCC),postoperative recurrence caused by residual tumor cells is a critical factor in the poor prognosis.Since surgical resection promotes the local angiogenesis at the tumor site,further exacerbating the proliferation and invasion of residual tumor cells,it is urgent to inhibit angiogenesis after surgery.Here,a functional peptide-based nanomedicine was obtained from peptide–drug conjugates,which are composed of a hydrophilic targeting motif(vascular endothelial growth factor family and their receptors(VEGFR)targeting peptide for anti-angiogenesis),an ester-linked hydrophobic oridonin(ORI).The nanomedicine exhibits esterase-catalyzed disassembly and drug release,significantly enhanced the anti-tumor efficacy of chemotherapeutics in a postoperative tumor recurrence model through synergistic anti-angiogenic strategies.This study provides an integrated solution for anti-angiogenesisaugmented chemotherapy and demonstrates the encouraging potential for postoperative treatment.

A Political Economics Analysis of Data Participation in Capitalism

Nowadays,as the development of science and technology promotes the continuous change of the force of production,data is becoming an increasingly important production factor that is deeply involved in the process of production,circulation,distribution and consumption in capitalist society.This study aims to explore the application of data in capitalist production and its implications.We analyzes the data from the labor process and the process of producing surplus value,from which it is concluded that the application of data in the general production process does not deviate from the category of the“Labor Theory of Value”.In addition,we distinguish the performance of data in the four links of surplus value production,realization,distribution and redistribution,thereby illustrating the positive role of data in the capitalist economy.We also identify changes in the value composition caused by data.

Warming and grazing enhance litter decomposition and nutrient release independent of litter quality in an alpine meadow

Warming and grazing,and ltter quality jointly determine liter decomposition and nutrient releases in grazing ecosystems.However,their effects have previously been studied in isolation.We conducted a two factorial experiment with asymmetric warming using infrared heaters and moderate grazing in an alpine meadow.Litter samples were collected from all plots in each treatment,among which some subsamples were placed in their original plots and other samples were translocated to other treatment plots to test the relative effects of each treatment on litter decomposition and nutrient releases.We found that warming rather than grazing alone significantly increased total losses of litter mass,total organic carbon,total nitrogen(TN)and total phosphorus(TP)per unit area due to increases in both mass loss rates and ltter biomass.However,grazing with warming did not affect their total mass losses because increased mass loss was offset by decreased litter biomass compared with the control.Seasonal mean soil temperature better predicted litter decomposition than litter lignin content or carbon to nitrogen ratio.There were interactions between warming and grazing,but there were no interactions between them and litter quality on litter decomposition.The temperature sensitivity of TN loss was higher than that of TP loss per unit area.Our results suggest that increased temperature has a greater effect on litter decomposition and nutrient release than change in litter quality,and that more N release from litter could result in greater P deficiency in the alpine meadow.

Responses of biotic interactions of dominant and subordinate species to decadal warming and simulated rotational grazing in Tibetan alpine meadow

Warming increases competition among plant species in alpine communities by ameliorating harsh environmental conditions,such as low temperatures. Grazing, as the main human activity, may mitigate the effect of warming, as previously reported.However, it is critical to refine the effects of warming on biotic interactions among species, for example, by taking the competitive ability of species into consideration. Based on a 10-year warming and grazing experiment in a Tibetan alpine meadow, we evaluated interspecific biotic interactions of dominant and subordinate species, using the approach of interspecific spatial associations. Warming significantly increased competition between subordinate and dominant species as well as among subordinate species, but not among dominant species. Moreover, facilitation of dominant-subordinate species also increased under warming. Simulated rotational grazing had similar effects to warming, with increasing interspecific competition. Our results show that, when studying the effects of warming on biotic interactions among species, it is necessary to characterize different species pairs relative to their competitive ability, and that simulated rotational grazing does not mitigate the effects of warming in the long term. Our results also provide evidence that the spatial pattern of species is a critical mechanism in species coexistence.

Design of compensation pixel circuit with In-Zn-O thin film transistor for active-matrix organic light-emitting diode 3D display

This paper presents a new compensation pixe] circuit suitable for active-matrix organic light-emitting diode （AMOLED） stereoscopic three dimensional （3D~ displays with shutter glasses. The simultaneous emissio~ method was used to solve the crosstalk problem, in which the periods of initialization and threshold voltage detectio11 occur for each pixel of whole panel simultaneously. Furthermore, there was no need of the periods of initialization and threshold voltage detection from the second frame beginning by one-time detection method. employing threshold voltage The non-uniformity of the proposed pixel circuit was considerably low with an average value of 8.6% measured from 20 discrete proposed pixel circuits integrated by In-Zn-O thin film transistors （IZO TFTs）. It was shown that the OLED current almost remains constant for the number of frames up to 70 even the threshold voltage detection period only exists in the first frame.

Impact of obese levels on the hepatic expression of nuclear receptors and drug-metabolizing enzymes in adult and offspring mice

The prevalence of obesity-associated conditions raises new challenges in clinical medication.Although altered expression of drug-metabolizing enzymes(DMEs)has been shown in obesity,the impacts of obese levels(overweight,obesity,and severe obesity)on the expression of DMEs have not been elucidated.Especially,limited information is available on whether parental obese levels affect ontogenic expression of DMEs in children.Here,a high-fat diet(HFD)and three feeding durations were used to mimic different obese levels in C57BL/6 mice.The hepatic expression of five nuclear receptors(NRs)and nine DMEs was examined.In general,a trend of induced expression of NRs and DMEs(except for Cyp2c29 and 3a11)was observed in HFD groups compared to low-fat diet(LFD)groups.Differentialeffects of HFD on the hepatic expression of DMEs were found in adult mice at different obese levels.Family-based dietary style of an HFD altered the ontogenic expression of DMEs in the offspring older than 15 days.Furthermore,obese levels of parental mice affected the hepatic expression of DMEs in offspring.Overall,the results indicate that obese levels affected expression of the DMEs in adult individuals and that of their children.Drug dosage might need to be optimized based on the obese levels.

A versatile tool for tracking the differentiation of human embryonic stem cells

The ability of human embryonic stem cells(hESCs)to undergo indefinite self-renewal in vitro and to produce lineages derived from all three embryonic germ layers both in vitro and in vivo makes such cells extremely valuable in both clinical and research settings.However,the generation of specialized cell lineages from a mixture of differentiated hESCs remains technically difficult.Tissue specific promoter-driven reporter genes are power-ful tools for tracking cell types of interest in differentiated cell populations.Here,we describe the construction of modular lentivectors containing different tissue-specific promoters(Tα1 ofα-tubulin;aP2 of adipocyte Protein 2;and AFP of alpha fetoprotein)driving expression of humanized Renilla greenfluorescent protein(hrGFP).To this end,we used MultiSite gateway technology and employed the novel vectors to successfully monitor hESC differentiation.We present a versatile method permitting target cells to be traced.Our system will facilitate research in developmental biology,transplantation,and in vivo stem cell tracking.