Estimating Key Phenological Dates of Multiple Rice Accessions Using Unmanned Aerial Vehicle-Based Plant Height Dynamics for Breeding

Efficient and high-quality estimation of key phenological dates in rice is of great significance in breeding work. Plant height(PH) dynamics are valuable for estimating phenological dates. However, research on estimating the key phenological dates of multiple rice accessions based on PH dynamics has been limited. In 2022, field traits were collected using unmanned aerial vehicle(UAV)-based images across 435 plots, including 364 rice varieties. PH, dates of initial heading(IH) and full heading(FH), and panicle initiation(PI), and growth period after transplanting(GPAT) were collected during the rice growth stage. PHs were extracted using a digital surface model(DSM) and fitted using Fourier and logistic models. Machine learning algorithms, including multiple linear regression, random forest(RF), support vector regression, least absolute shrinkage and selection operator, and elastic net regression, were employed to estimate phenological dates. Results indicated that the optimal percentile of the DSM for extracting rice PH was the 95th(R^(2) = 0.934, RMSE = 0.056 m). The Fourier model provided a better fit for PH dynamics compared with the logistic models. Additionally, curve features(CF) and GPAT were significantly associated with PI, IH, and FH. The combination of CF and GPAT outperformed the use of CF alone, with RF demonstrating the best performance among the algorithms. Specifically, the combination of CF extracted from the logistic models, GPAT, and RF yielded the best performance for estimating PI(R^(2) = 0.834, RMSE = 4.344 d), IH(R^(2) = 0.877, RMSE = 2.721 d), and FH(R^(2) = 0.883, RMSE = 2.694 d). Overall, UAV-based rice PH dynamics combined with machine learning effectively estimated the key phenological dates of multiple rice accessions, providing a novel approach for investigating key phenological dates in breeding work.

Effect of dates on blood glucose and lipid profile among patients with type 2 diabetes

Poor fruit and vegetable consumption is one of the 10 major risk factors for mortality.There is a misconception regarding the consumption of dates among patients with diabetes.This manuscript assessed the effects of date consumption on fasting and postprandial blood glucose,glycated hemoglobin,total cholesterol,triglycerides,low-density lipoproteins,high-density lipoproteins,and microbial markers.Four literature databases were searched for relevant articles.Of the 595 studies retrieved,24 assessed the effects of dates on glycemic control and lipids.Overall,the evidence suggests that dates have a lowering effect on blood glucose.Dates reduce total cholesterol and triglyceride levels and increase high-density lipoprotein levels.Dates also promote the abundance of beneficial gut microbiota.Therefore,patients with diabetes and dyslipidemia can consume dates to reduce their blood glucose,cholesterol,and triglycerides.

Effects of Seeding Date and Density on Yield and Agronomic Traits of Millet : A Case Study of Wangu 098 Variety of Millet

[Objectives]To find out a suitable cultivation technique of Wangu 098 in Nanyang area,speed up the popularization,demonstration and application of Wangu 098,and provide a theoretical and practical basis for adjusting the planting structure and realizing the matching of improved varieties and methods.[Methods]The new self-bred millet variety Wangu 098 was used as the material,and the two-factor split zone experimental design was adopted.The effects of different sowing dates and densities on the yield,growth period and agronomic characters of millet were studied.[Results]The interaction of seeding date and density had a great effect on the yield and plant traits of millet.Millet yield was significantly and positively correlated with plant height,panicle length,single panicle weight,panicle grain weight and tiller number.[Conclusions]The reasonable combination of seeding date and density could give full play to the yield potential of millet.According to the experimental results and cultivation experience,the suitable seeding date of millet in Nanyang area is in the first and middle ten days of June,and the best density is about 750000 plants/ha.However,after June 30,the seeding millet did not tiller,so the density should be increased to more than 900000 plants/ha to obtain higher yield.In terms of cultivation and management,timely seeding,reasonable close planting,and coordination of vegetative growth and reproductive growth can make the plant tall and strong,panicle long and thick,and improve the yield of millet.

以学生为中心的BOPPPS教学模型+DATE监控模式在药理学教学中的应用探索

随着教育改革的推广和深入,当前教学的模式开始逐渐的丰富化和多元化,各个教学理念、教学模型层出不穷,在这样的背景下,结合学科的特质和需求,设计良好的教学模式,认知理论和构建主义是BOPPPS教学模型的理论和依据,该模型是一个能够帮助教师分解并分析教学过程、找出教学盲点、改善并提升教学成效的工具。如何使学生在课堂上最大限度的掌握知识,是其关注的重点,教学互动和反馈是其突出的特点。BOPPPS教学模型就是一个基于体验式学习模型的教学框架,是一种有效的课程设计模式,强调学生主动参与式学习,体现“以学生为中心、教师为主导”教学理念设计,为高质量的有效课堂提供了理论基础。因此,本文旨在探讨以学生为中心的BOPPPS教学模型与DATE监控模式在药理学教学中的应用及其效果。通过实践与研究,发现BOPPPS模型能够有效地提高学生的主动参与度和学习效果,而DATE监控模式则有助于及时发现和解决学生学习中的问题。以供一线教学教师作为教学提供参考和依据,有效提升药理学教学质量。

Effects of sowing date and ecological points on yield and the temperature and radiation resources of semi-winter wheat

Exploring the effects of sowing date and ecological points on the yield of semi-winter wheat is of great significance.This study aims to reveal the effects of sowing date and ecological points on the climate resources associated with wheat yield in the Rice–Wheat Rotation System.With six sowing dates,the experiments were carried out in Donghai and Jianhu counties,Jiangsu Province,China using two semi-winter wheat varieties as the objects of this study.The basic seedlings of the first sowing date (S1) were planted at 300×10^(4)plants ha^(-1),which was increased by 10%for each of the delayed sowing dates (S2–S6).The results showed that the delay of sowing date decreased the number of days,the effective accumulated temperature and the cumulative solar radiation in the whole growth period.The yields of S1 were higher than those of S2 to S6 by 0.22–0.31,0.5–0.78,0.86–0.98,1.14–1.38,and 1.36–1.59 t ha^(–1),respectively.For a given sowing date,the growth days increased as the ecological point was moved north,while both mean daily temperature and effective accumulative temperature decreased,but the cumulative radiation increased.As a result,the yields at Donghai County were 0.01–0.39 t ha–1lower than those of Jianhu County for the six sowing dates.The effective accumulative temperature and cumulative radiation both had significant positive correlations with yield.The average temperature was significantly negatively correlated with the yield.The decrease in grain yield was mainly due to the declines in grains per spike and 1 000-grain weight caused by the increase in the daily temperature and the decrease in the effective accumulative temperature.

Untargeted metabolomics analysis of four date palm(Phoenix dactylifera L.)cultivars using MS and NMR

Since ancient times,the inhabitants of dry areas have depended on the date palm(Phoenix dactylifera L.)as a staple food and means of economic security.For example,dates have been a staple diet for the inhabitants of the Arabian Peninsula and Sahara Desert in North Africa for millennia and the local culture is rich in knowledge and experience with the benefits of dates,suggesting that dates contain many substances essential for the human body.Madinah dates are considered one of the most important types of dates in the Arabian Peninsula,with Ajwa being one of the most famous types and grown only in Madinah,Saudi Arabia.Date seeds are traditionally used for animal feed,seed oil production,cosmetics,and as a coffee substitute.Phytochemical compounds that have been detected in date fruits and date seeds include phenolic acids,carotenoids,and flavonoids.Phenolic acids are the most prevalent bioactive constituents that contribute to the antioxidant activity of date fruits.The bioactive properties of these phytochemicals are believed to promote human health by reducing the risk of diseases such as chronic inflammation.Ajwa dates especially are thought to have superior bioactivity properties.To investigate these claims,in this study,we compare the metabolic profiles of Ajwa with different types of dates collected from Saudi Arabia and Tunisia.We show by UHPLC-MS that date seeds contain several classes of flavonoids,phenolic acids,and amino acid derivatives,including citric acid,malic acid,lactic acid,and hydroxyadipic acid.Additionally,GC-MS profiling showed that date seeds are richer in metabolite classes,such as hydrocinnamic acids(caffeic,ferulic and sinapic acids),than flesh samples.Deglet N fruit extract(minimum inhibitory concentration:27 MIC/μM)and Sukkari fruit extract(IC_(50):479±0.58μg/mL)have higher levels of antibacterial and antioxidative activity than Ajwa fruits.However,the seed analysis showed that seed extracts have better bioactivity effects than fruit extracts.Specifically,Ajwa extract showed the best MIC and strongest ABTS radical-scavenging activity among examined seed extracts(minimum inhibitory concentration:20μM;IC_(50):54±3.61μg/mL).Our assays are a starting point for more advanced in vitro antibacterial models and investigation into the specific molecules that are responsible for the antioxidative and anti-bacterial activities of dates.

Biological Profile of People Living with Human Immunodeficiency Virus Starting Treatment in Kinshasa, Democratic Republic of the Congo

Context: The biochemical assessment is a real-time indicator of the state and evolution of an infection. Among other things, it makes it possible to determine the right moment when it becomes necessary to start or change a treatment. Objective: The objective of this study is to present the Biological profile of People Living with HIV starting AntiRetroViral treatment in Kinshasa in the era of Dolutegravir. Methods: The present study is a descriptive cross-sectional to determine the biological profile of People Living with HIV (PLHIV) starting AntiRetroViral Treatment (ART). The patient inclusion period was from October 4, 2021 to February 15, 2022. Sixteen centers were included. A sample of 5 ml of blood was taken in a tube with EDTA. Patients were randomly included consecutively in the centers during consultations. The population was made up of adults aged over 18, infected with HIV and starting ART. The parameters of interest retained for the present study were: sex, age, hemoglobin level, blood sugar, urea, creatinine, transaminases, total cholesterol, triglycerides, proteins total, as well as amylase. Results: 119 patients were included in this study in accordance with the inclusion criteria;67 (56.3%) are female, giving a sex ratio of 1.29 in favor of women. The average age of the patients is 39.87 ± 12.36 years. The most represented age group is that of 36 to 45 years with 37 patients (31.9%). The mean values of the biological parameters of the patients at the start of ART are as follows: 31.61 ± 20.71 IU/L for ALT/SGPT, 25.81 ± 19.96 IU/L for AST/SGOT, 79.35 ± 49.49 IU/L for Amylase, 108.13 ± 62.17 mg/dl for Total Cholesterol, 2.77 ± 1.27 mg/dl for Creatinine, 72.53 ±22.23 mg/dl for Glycaemia, 10.30 ± 2.33 g/dl for Hemoglobin, 7.91 ± 1.75 g/dl for Total Protein, 131.23 ± 68.80 mg/dl for Triglycerides, and 33.61 ± 26.27 mg/dl for Urea. Conclusion: Mean values of PLHIV are, for the most part, within the normal range. The average creatinine is higher than the normal average value while the average total cholesterol is below the limit values.

Influence of Planting Date on the Incidence and Severity of Leaf Spot Disease in Telfairia occidentalis Hook f.

Telfairia occidentalis Hook f. is attacked by a destructive fungal pathogen Epicoccum sorghinum which causes leaf spot disease in the field. In Came-roon, this critically important seed and leaf vegetable is predominantly culti-vated under natural environmental conditions. An experiment was conducted in 2019 and 2020 during the long and short rainy seasons in Santchou to de-termine the influence of planting dates between seasons on the incidence and severity of leaf spot disease. The design used was a 2 by 4 factorial random-ized complete block design with three replications and four sowing dates. Data for disease incidence and severity documented fortnightly, were submitted to analysis of variance using SPSS version 23, and the means were separated by Duncan’s multiple range test (DMRT) at a 95% confidence interval. Statistical analysis revealed that the long rainy season registered a significantly (p p < 0.05) disease incidences and severities to other planting dates investi-gated. We established that the first three planting dates in the long rainy season could be a management practice to reduce disease prevalence.

Virological and Molecular Profile of People Living with the Human Immunodeficiency Virus Starting Dolutegravir Based Antiretroviral Treatment in Kinshasa, Democratic Republic of Congo

Context: Despite the new recommendations “Test and Treat”, the virological and molecular parameters remain important information for Antiretroviral Treatment and adequate for monitoring of patients infected with HIV/AIDS. Objective: the Objective of this study is to present the virological and molecular profile of People Living with HIV starting Antiretroviral Therapy in Kinshasa in the era of the Dolutegravir. Methods: This was a transversal study to determine virological and molecular profile of People Living with HIV (PLHIV) starting an ARV Treatment. The patient’s inclusion period was from October 04, 2021 to February 15, 2022. A sample of 5 ml of blood was taken in a tube with EDTA anticoagulant for Molecular Biology analyzes (Viral Load and Sequencing) in all HIV patients, after reading and signing informed consent. The population was made up of adult patients over the age of 18, infected with HIV and starting ART. Results: 119 patients (56.3% of women) were included in this study, thus a sex-ratio of 1.29. The average age of patients included was 39.87 ± 12.36 years. The most represented age group is that of 36 to 45 with 37 patients (31.9%) followed by that from 26 to 35 years with 24 patients (20.7%). Out of 119 patients, 21 patients had an undetectable Viral Load (VL). The median value of VL was 4.16 log10 RNA copies/ml. 114 samples were successfully amplified. Subtype A was dominant with 23 cases (20.2%);followed by the subtype C and CRF02_AG each with 14.0%, and D (10.5 %). K65R (1.8%), T69P/N (4.4%), K70R (7.9%) and M184V (7.0%) mutations were listed as existing mutations for Nucleotide Transcriptase Inhibitors. Conclusion: 38 patients (31.93%) started the TARV with a positive virological prognosis. The subtype A remains dominant in Kinshasa with 23 cases (20.2%);followed by the subtype C and CRF02_AG each with 14.0%. For Inhibitors of Transcriptase Reverse Nucleotide;K65R, T69P/N, K70E/R and M184V mutations were found in patients’ naive of ARV Treatment.

In Situ Rb-Sr Dates of Muscovite and Sulfur Isotope of Pyrite from the Yangshan Gold Deposit in Western Qinling,China

Located along the southern part of the West Qinling orogenic belt,the Yangshan gold deposit is one of the largest in China.The major gold ores of Yangshan are disseminated in metasedimentary host rocks with minor native gold amounts in stibnite-gold quartz veins.Pyrite and arsenopyrite are the major Au-bearing minerals.Hydrothermal muscovite from gold-bearing quartz veins was dated using the in situ Rb-Sr method to determine the formation age of the Yangshan gold deposit.The Rb-Sr isochron date of the muscovite yielded 210.1±5.6 Ma(MSWD=1.2).This date is near the lower end of the period of the mineralized granitic dykes(210.49-213.10 Ma).Two stages of gold enriching process are recognized in the gold-bearing pyrite:the first is incorporated with the Co,Cu,As,Ni enrichment;and the second is accompanied by Bi,Co,Ni,Pb,Cu,Sb concentration.The in-situ sulfur isotopic values of pyrites show a restrictedΔ34s range of-1.43‰to 2.86‰with a mean value of 0.43‰.Trace-element mapping and in-situ sulfur isotopic analysis of pyrite suggest that the sulfur deposits are likely derived from a magmatic source and likely assimilated by sulfur from the sedimentary bedrock.Thus,magmatism plays a critical role in the formation of the Yangshan gold deposit.

Investigation of Aegilops umbellulata for stripe rust resistance,heading date,and the contents of iron,zinc,and gluten protein

Aegilops umbellulata(UU)is a wheat wild relative that has potential use in the genetic improvement of wheat.In this study,46 Ae.umbellulata accessions were investigated for stripe rust resistance,heading date(HD),and the contents of iron(Fe),zinc(Zn),and seed gluten proteins.Forty-two of the accessions were classified as resistant to stripe rust,while the other four accessions were classified as susceptible to stripe rust in four environments.The average HD of Ae.umbellulata was significantly longer than that of three common wheat cultivars(180.9 d vs.137.0 d),with the exception of PI226500(138.9 d).The Ae.umbellulata accessions also showed high variability in Fe(69.74-348.09 mg kg^(-1))and Zn(49.83-101.65 mg kg^(-1))contents.Three accessions(viz.,PI542362,PI542363,and PI554399)showed relatively higher Fe(230.96-348.09 mg kg^(-1))and Zn(92.46-101.65 mg kg^(-1))contents than the others.The Fe content of Ae.umbellulata was similar to those of Ae.comosa and Ae.markgrafii but higher than those of Ae.tauschii and common wheat.Aegilops umbellulata showed a higher Zn content than Ae.tauschii,Ae.comosa,and common wheat,but a lower content than Ae.markgrafii.Furthermore,Ae.umbellulata had the highest proportion of γ-gliadin among all the species investigated(Ae.umbellulata vs.other species=mean 72.11%vs.49.37%;range:55.33-86.99%vs.29.60-67.91%).These results demonstrated that Ae.umbellulata exhibits great diversity in the investigated traits,so it can provide a potential gene pool for the genetic improvement of these traits in wheat.

Modeling Date Palm Trunk Fibers (DPTF) Packed Bed Adsorption Performances for Cadmium Removal from Aqueous Wastewater

In this study,the potential of a low-cost bio-adsorbent,taken directly from Date Palm Trunk Fibers(DPTF)agricultural wastes,for cadmium ions removal from wastewaters is examined.The performances of this adsorbent are evaluated by building breakthrough curves at different bed heights and flow rates while keeping other parameters,such as the initial feed concentration,pH,and particle size,constant.The results indicate that the maximum cadmium adsorption capacity of DTPF can be obtained from the Thomas model as 51.5 mg/g with the most extended mass transfer zone of 83 min at the lowest flow rate at 5 ml/min.The saturation concentrations(NO)and the rate constant(kab)obtained from the BDST(bed depth service time)model are 7022.16 mg/l and 0.0536 l/mg.min,respectively.Using the Yon-Nelsen Model,it is found that operating at a lower flow rate leads to a larger value of the elapsed needed time to reach a 50%breakthrough.The Wolborska model indicates that the bed capacity increases with decreasing the flow rate,and the adsorbent can achieve a greater external mass transfer kinetic coefficient(2.271/min)at a higher flow rate.

Detecting Climate Change Trend, Size, and Change Point Date on Annual Maximum Time Series Rainfall Data for Warri, Nigeria

The study focused on the detection of indicators of climate change in 24-hourly annual maximum series (AMS) rainfall data collected for 36 years (1982-2017) for Warri Township, using different statistical methods yielded a statistically insignificant positive mild trend. The IMD and MCIMD downscaled model’s time series data respectively produced MK statistics varying from 1.403 to 1.4729, and 1.403 to 1.463 which were less than the critical Z-value of 1.96. Also, the slope magnitude obtained showed a mild increasing trend in variation from 0.0189 to 0.3713, and 0.0175 to 0.5426, with the rate of change in rainfall intensity at 24 hours duration as 0.4536 and 0.42 mm/hr.year (4.536 and 4.2 mm/decade) for the IMD and the MCIMD time series data, respectively. The trend change point date occurred in the year 2000 from the distribution-free CUSUM test with the trend maintaining a significant and steady increase from 2010 to 2015. Thus, this study established the existence of a trend, which is an indication of a changing climate, and satisfied the condition for rainfall Non-stationary intensity-duration-frequency (NS-IDF) modeling required for infrastructural design for combating flooding events.

膨胀循环氢氧发动机低箱压起动特性研究

为满足长时间在轨低温上面级对发动机低入口压力起动的需求,对膨胀循环氢氧发动机低箱压起动特性进行了仿真和试验研究,建立了较为准确的起动特性仿真模型,完成了地面环境和高空模拟环境氢入口低箱压起动试验。结果表明,氢入口压力越低,发动机起动加速性越慢,两者呈类似双曲线关系;降低喷管出口背压有利于发动机起动,氢入口压力越低,背压对起动加速性的影响越大。

基于元学习个性化推荐研究综述

推荐系统作为缓解“信息过载”的工具,为用户过滤冗余信息并提供个性化服务,近年来得到了广泛应用。然而,实际推荐场景中,通常存在冷启动与不同推荐算法难以根据实际环境自适应选择等问题。元学习因其具有基于少量训练样本快速学会新知识和技能的优点,被越来越多地应用于推荐系统相关研究中。对现有基于元学习技术缓解推荐系统冷启动问题以及自适应推荐问题的主要研究进行探讨。首先,分析了基于元学习推荐在上述2个方面已取得的相关研究进展;然后,指出了现有元学习推荐研究存在难以适应复杂任务分布、计算代价高和容易陷入局部最优等问题;最后,对元学习在推荐系统领域的一些最新研究方向进行了展望。

高效液相色谱法测定阿维巴坦钠起始物料(2S,5R)-5-[(苄氧基)氨基]哌啶-2-羧酸乙酯的含量

目的:建立测定阿维巴坦钠起始物料(2S,5R)-5-[(苄氧基)氨基]哌啶-2-羧酸乙酯含量的方法。方法:采用Hypersil ODS2色谱柱(4.6 mm×250.0 mm, 5.0μm),流动相A为0.01 mol/L磷酸二氢铵溶液,流动相B为乙腈,流动相A到流动相B(50∶50)运行时间11 min,流速为1.0 mL/min,波长为210 nm,柱温为40℃,进样量为10μL。结果:阿维巴坦钠起始物料(2S,5R)-5-[(苄氧基)氨基]哌啶-2-羧酸乙酯都得到良好的分离。结论:高效液相色谱法灵敏、快速、准确、可靠,可用于阿维巴坦钠起始物料(2S,5R)-5-[(苄氧基)氨基]哌啶-2-羧酸乙酯含量测定。

激光剥蚀-扇形磁场电感耦合等离子体质谱法同时测定锆石U-Pb年龄和微量元素含量

激光剥蚀-扇形磁场电感耦合等离子体质谱(LA-SF-ICP-MS)具有高灵敏度特征,被广泛应用于锆石等含U矿物原位微区U-Pb定年研究,但磁偏转式质量分析器的使用导致该质谱仪扫描速度相对较慢,可能影响U-Pb同位素与其他关键微量元素的同时采集。本文通过优化仪器信号稳定性和实验方法,对目前常用的7种锆石U-Pb标准样品进行U-Pb定年和Ti、REEs、Hf等关键元素同时定量分析,探讨了多元素同时分析方法的可行性及对于U-Pb定年结果的影响。实验结果表明,相对于LA-SF-ICP-MS仅检测U-Pb同位素方法,同时开展多元素含量检测可能会使U-Pb同位素信号强度稳定性下降,导致单点U-Pb年龄结果误差及离散程度增大。与仅测定U-Pb同位素年龄的测定结果相比较,根据不同锆石样品中U-Pb同位素含量高低,多元素同时检测获得分析点的206Pb/238U年龄和207Pb/235U年龄变化范围不同程度地增大,其中207Pb/235U年龄受影响明显,单点207Pb/235U年龄误差从~1.5%增大至~2.0%,单点年龄的相对标准偏差(RSD)从0.5%~1.3%增大至1.2%~3.3%。尽管如此,多元素同时检测方法对于各样品最终测定年龄没有明显的影响,相对于TIMS年龄,各样品的谐和年龄和206Pb/238U加权平均年龄偏差分别小于1.0%和0.7%,完全满足U-Pb同位素地质年代学测试要求。同时测定锆石样品中的关键微量元素含与其推荐值相对误差小于10%。因此,采用LA-SF-ICP-MS可以同时准确地测定锆石U-Pb年龄和微量元素含量,该方法亦可用于其他副矿物U-Pb年龄与关键微量元素同时测定。

数字经济、创业与中等收入群体规模

利用马克思资本循环理论、蒂蒙斯创业理论阐释数字经济扩大中等收入群体规模的理论逻辑,并利用2012—2021年中国31个省份的面板数据检验了数字经济对中等收入群体规模的影响。研究发现:数字经济能显著扩大中等收入群体规模。机制研究表明:数字经济能通过促进创业而扩大中等收入群体规模。具体而言,数字经济有助于促进创业融资和优化创业企业的要素配置,从而有助于扩大中等收入群体规模。进一步研究发现:良好的营商环境能强化数字经济对创业的促进作用,从而能强化数字经济对中等收入群体规模的扩大作用。异质性检验结果表明:组织型创业与自我雇佣型创业都能使数字经济更好地发挥其对中等收入群体规模的扩大作用;在数字经济的支持下,无论是在制造业中创业,还是在服务业中创业,均能显著扩大中等收入群体规模。

柔性低频输电系统的主变稳态负序差动保护

为了解决常规纵差保护难以适用于低频系统的问题,通过分析低频系统的序分量抑制策略,并根据低频系统故障进入稳态后单侧有负序注入的特征,提出一种基于稳态负序分量的主变差动保护方法。为防止该差动保护在区外故障时因电流互感器饱和出现误动,通过对比分析三类制动电流计算方式的制动性能,得到了差动保护的制动方程和制动系数。为解决励磁涌流、电流互感器断线可能导致误动的问题,提出了相电压突变量的差动保护开放条件。仿真分析表明,该方法能够灵敏反映区内金属性故障及轻微故障,在区外故障伴随电流互感器饱和时有可靠的制动裕度。

南岭湘南吴家坪锡矿成岩成矿时代研究

南岭吴家坪锡矿为湖南大义山地区近年新发现的具有中型以上远景规模的云英岩型矿床,矿体呈脉状产于大义山复式花岗岩体内部,受NE向断裂控制。为确定其成岩、成矿时代,总结大义山地区成矿规律,指导区域找矿及勘查工作,对赋矿围岩中粗粒斑状黑云母二长花岗岩(PM21-19)、中细粒斑状黑云母二长花岗岩(PM21-27)进行了LA−ICP−MS锆石U−Pb定年研究。测年结果表明,其成岩年龄为157.1±1.1 Ma(MSWD=0.55)和153.7±1.2 Ma(MSWD=0.55),属燕山早期。同时,获得云英岩型锡矿石中石英Rb−Sr等时线年龄为148.1±2.1 Ma(MSWD=0.52)。结合区域资料认为,吴家坪锡矿成岩成矿时代为燕山早期,属南岭地区中生代成岩成矿高峰期(160~150 Ma)的产物。