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MHz cut-off frequency and permeability mechanism of iron-based soft magnetic composites
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作者 Xiao-Wei Jin Tong Li +1 位作者 Hui-Gang Shi De-Sheng Xue 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第9期560-564,共5页
The lack of soft magnetic composites with high power density in MHz frequency range has become an obstacle in the efficient operation of the electrical and electronic equipments.Here,a promising method to increase the... The lack of soft magnetic composites with high power density in MHz frequency range has become an obstacle in the efficient operation of the electrical and electronic equipments.Here,a promising method to increase the cut-off frequency of iron-based soft magnetic composites to hundreds of MHz is reported.The cut-off frequency is increased from 10 MHz to 1 GHz by modulating the height of the ring,the distribution of particles,and the particle size.The mechanism of cut-off frequency and permeability is the coherent rotation of domain modulated by inhomogeneous field due to the eddy current effect.An empirical formula for the cut-off frequency in a magnetic ring composed of iron-based particles is established from experimental data.This work provides an effective approach to fabricate soft magnetic composites with a cut-off frequency in hundreds of MHz. 展开更多
关键词 cut-off frequency PERMEABILITY EDDY current effect SOFT magnetic composites
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Cut-off value of glycated hemoglobin A1c for detecting diabetic retinopathy in the Chinese population
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作者 Yan Wen Qing Wang 《World Journal of Diabetes》 SCIE 2024年第7期1531-1536,共6页
BACKGROUND Glycated hemoglobin A1c(HbA1c)is considered the most suitable for diabetes mellitus diagnosis due to its accuracy and convenience.However,the effect of HbA1c on diabetic retinopathy(DR)in the Han and Korean... BACKGROUND Glycated hemoglobin A1c(HbA1c)is considered the most suitable for diabetes mellitus diagnosis due to its accuracy and convenience.However,the effect of HbA1c on diabetic retinopathy(DR)in the Han and Korean populations in Jilin,China,remains inconclusive.AIM To determine the best cut-off of HbA1c for diagnosing DR among the Chinese.METHODS This cross-sectional study included 1933 participants from the Yanbian area of Jilin Province,China.Trained investigators employed a questionnaire-based survey,physical examination,laboratory tests,and fundus photography for the investigation.The best cut-off value for HbA1c was established via the receiver operating characteristic curve.The factors associated with HbA1c-associated risk factors were determined via linear regression.RESULTS The analysis included 887 eligible Chinese Han and Korean participants,591 of whom were assigned randomly to the training set and 296 to the validation set.The prevalence of DR was 3.27% in the total population.HbA1c of 6.2% was the best cut-off value in the training set,while it was 5.9% in the validation set.In both Chinese Han and Korean populations,an HbA1c level of 6.2% was the best cut-off value.The optimal cut-off values of fasting blood glucose(FBG)≥7 mmol/L and<7 mmol/L were 8.1% and 6.2% respectively in Han populations,while those in Korean populations were 6.9%and 5.3%,respectively.Age,body mass index,and FBG were determined as the risk factors impacting HbA1c levels.CONCLUSION HbA1c may serve as a useful diagnostic indicator for DR.An HbA1c level of 6.2% may be an appropriate cut-off value for DR detection in the Chinese population. 展开更多
关键词 Diabetic retinopathy Glycated hemoglobin A1c cut-off value Age Body mass index Fasting blood glucose
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Convergence Phenomenon with Fourier Series of tg(x2)and Alike
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作者 Alfred Wünsche 《Advances in Pure Mathematics》 2024年第7期556-595,共40页
The Fourier series of the 2π-periodic functions tg(x2)and 1sin(x)and some of their relatives (first of their integrals) are investigated and illustrated with respect to their convergence. These functions are Generali... The Fourier series of the 2π-periodic functions tg(x2)and 1sin(x)and some of their relatives (first of their integrals) are investigated and illustrated with respect to their convergence. These functions are Generalized functions and the convergence is weak convergence in the sense of the convergence of continuous linear functionals defining them. The figures show that the approximations of the Fourier series possess oscillations around the function which they represent in a broad band embedding them. This is some analogue to the Gibbs phenomenon. A modification of Fourier series by expansion in powers cosn(x)for the symmetric part of functions and sin(x)cosn−1(x)for the antisymmetric part (analogous to Taylor series) is discussed and illustrated by examples. The Fourier series and their convergence behavior are illustrated also for some 2π-periodic delta-function-like sequences connected with the Poisson theorem showing non-vanishing oscillations around the singularities similar to the Gibbs phenomenon in the neighborhood of discontinuities of functions. . 展开更多
关键词 Gibbs phenomenon Generalized Functions Weak Convergence Chebyshev Polynomials of First and Second Kind Even and Odd Generating Functions for Chebyshev Polynomials POLYLOGARITHMS Completeness Relations
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Subseasonal Prediction of Early-summer Northeast Asian Cut-off Lows by BCC-CSM2-HR and GloSea5 被引量:3
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作者 Yu NIE Jie WU +4 位作者 Jinqing ZUO Hong-Li REN Adam A.SCAIFE Nick DUNSTONE Steven C.HARDIMAN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2023年第11期2127-2134,共8页
Northeast Asian cut-off lows are crucial cyclonic systems that can bring temperature and precipitation extremes over large areas.Skillful subseasonal forecasting of Northeast Asian cut-off lows is of great importance.... Northeast Asian cut-off lows are crucial cyclonic systems that can bring temperature and precipitation extremes over large areas.Skillful subseasonal forecasting of Northeast Asian cut-off lows is of great importance.Using two dynamical forecasting systems,one from the Beijing Climate Center(BCC-CSM2-HR)and the other from the Met Office(GloSea5),this study assesses simulation ability and subseasonal prediction skill for early-summer Northeast Asian cut-off lows.Both models are shown to have good ability in representing the spatial structure of cut-off lows,but they underestimate the intensity.The skillful prediction time scales for cut-off low intensity are about 10.2 days for BCC-CSM2-HR and 11.4 days for GloSea5 in advance.Further examination shows that both models can essentially capture the initial Rossby wave train,rapid growth and decay processes responsible for the evolution of cut-off lows,but the models show weaker amplitudes for the three-stage processes.The underestimated simulated strength of both the Eurasian midlatitude and East Asian subtropical jets may lead to the weaker local eddy-mean flow interaction responsible for the cut-off low evolution. 展开更多
关键词 Northeast Asia cut-off lows subseasonal prediction skill jet stream
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Correction of dynamic Brazilian disc tensile strength of rocks under preloading conditions considering the overload phenomenon and invoking the Griffith criterion 被引量:1
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作者 Kaiwen Xia Yuchao Yu +1 位作者 Bangbiao Wu Wei Yao 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第8期1986-1996,共11页
Dynamic tensile failure is a common phenomenon in deep rock practices,and thus accurately evaluating the dynamic tensile responses of rocks under triaxial pressures is of great significance.The Brazilian disc(BD)test ... Dynamic tensile failure is a common phenomenon in deep rock practices,and thus accurately evaluating the dynamic tensile responses of rocks under triaxial pressures is of great significance.The Brazilian disc(BD)test is the suggested method by the International Society for Rock Mechanics and Rock Engineering(ISRM)for measuring both the static and dynamic tensile strengths of rock-like materials.However,due to the overload phenomenon and the complex preloading conditions,the dynamic tensile strengths of rocks measured by the BD tests tend to be overestimated.To address this issue,the dynamic BD tensile strength(BTS)of Fangshan marble(FM)under different preloading conditions were measured through a triaxial split Hopkinson pressure bar(SHPB).The fracture onset in BD specimen was captured through a strain gage around the disc center.The discrepancy between the traditional tensile strength(TTS,determined by the peak load P_(f) of the BD specimen)and the nominal tensile strength(NTS,obtained from the load P_(i) when the diametral fracture commences in the tested BD specimen)was applied to quantitatively evaluating the overload phenomenon.The Griffith criterion was used to rectify the calculation of the tensile stress at the disc center under triaxial stress states.The results demonstrate that the overload ratio(s)increases with the loading rate(σ)and decreases with the hydrostatic pressure(σ_(s)).The TTS corrected by the Griffith criterion is independent of theσ_(s)due to the overload phenomenon,while the NTS corrected by the Griffith criterion is sensitive to both the andσ.Therefore,it is essential to modify the tensile stress in dynamic confined BD tests using both the overload correction and the Griffith criterion rectification to obtain the accurate dynamic BTS of rocks. 展开更多
关键词 Dynamic brazilian disc test Overload phenomenon Dynamic tensile strength Hydrostatic pressure Griffith criterion
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Asymmetric Environmental Regulation:Mechanism and a Yardstick Phenomenon 被引量:1
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作者 Yu Yazhuo Zhang Huilin Zhang Pingdan 《China Economist》 2023年第1期87-107,共21页
In discussing the policy effects of environmental regulation,we should focus not only on whether environmental regulation helps improve the environmental and economic performance of firms,but also on how such improvem... In discussing the policy effects of environmental regulation,we should focus not only on whether environmental regulation helps improve the environmental and economic performance of firms,but also on how such improvement is materialized,i.e.whether the obsolete mode of production is reversed.After matching the database of China’s industrial enterprises with that of pollution emissions from these industrial enterprises,this paper identifies the asymmetric scope of clean production standards to test the effect of environmental regulation on the total factor productivity(TFP)of the industrial enterprises.Our empirical research finds that the implementation of clean production standards may induce TFP improvement.However,such improvement only occurs for polluters who cannot or who barely meet clean production standards and does little to improve the production standards of polluters with low pollution emission,reflecting the yardstick phenomenon of the asymmetric environmental regulation policy effect:While polluters are forced to improve,clean enterprises that pollute less are more likely to take no action.Further research finds that such TFP improvement is materialized primarily by means of overall firm optimization;the compensation effect is insignificant and does not reverse the backward mode of production.Polluters cope with the implementation of clean production standards by purchasing more equipment and expanding capacity,which adds to the tension between the expansion of capacity and the abatement of pollution emission. 展开更多
关键词 ENVIRONMENTAL REGULATION CLEAN production STANDARDS TFP asymmetry yardstick phenomenon
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A new DRIE cut-off material in SOG MEMS process
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作者 Chaowei Si Yingchun Fu +4 位作者 Guowei Han Yongmei Zhao Jin Ning Zhenyu Wei Fuhua Yang 《Journal of Semiconductors》 EI CAS CSCD 2023年第4期98-102,共5页
The silicon on glasses process is a common preparation method of micro-electro-mechanical system inertial devices,which can realize the processing of thick silicon structures.This paper proposes that indium tin oxides... The silicon on glasses process is a common preparation method of micro-electro-mechanical system inertial devices,which can realize the processing of thick silicon structures.This paper proposes that indium tin oxides(ITO)film can serve as a deep silicon etching cut-off layer because ITO is less damaged under the attack of fluoride ions.ITO has good electrical conductivity and can absorb fluoride ions for silicon etching and reduce the reflection of fluoride ions,thus reducing the foot effect.The removal and release of ITO use an acidic solution,which does not damage the silicon structure.Therefore,the selection of the sacrificial layer has an excellent effect in maintaining the shape of the MEMS structure.This method is used in the preparation of MEMS accelerometers with a structure thickness of 100μm and a feature size of 4μm.The over-etching of the bottom of the silicon structure caused by the foot effect is negligible.The difference between the simulated value and the designed value of the device characteristic frequency is less than 5%.This indicates that ITO is an excellent deep silicon etch stopper material. 展开更多
关键词 SOG process DRIE cut-off layer ITO film foot effect
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Multifractal estimation of NMR T_(2) cut-off value in low-permeability rocks considering spectrum kurtosis: SMOTE-based oversampling integrated with machine learning
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作者 Xiao-Jun Chen Rui-Xue Zhang +4 位作者 Xiao-Bo Zhao Jun-Wei Yang Zhang-Jian Lan Cheng-Fei Luo Jian-Chao Cai 《Petroleum Science》 SCIE EI CAS CSCD 2023年第6期3411-3427,共17页
The transverse relaxation time (T_(2)) cut-off value plays a crucial role in nuclear magnetic resonance for identifying movable and immovable boundaries, evaluating permeability, and determining fluid saturation in pe... The transverse relaxation time (T_(2)) cut-off value plays a crucial role in nuclear magnetic resonance for identifying movable and immovable boundaries, evaluating permeability, and determining fluid saturation in petrophysical characterization of petroleum reservoirs. This study focuses on the systematic analysis of T_(2) spectra and T_(2) cut-off values in low-permeability reservoir rocks. Analysis of 36 low-permeability cores revealed a wide distribution of T_(2) cut-off values, ranging from 7 to 50 ms. Additionally, the T_(2) spectra exhibited multimodal characteristics, predominantly displaying unimodal and bimodal morphologies, with a few trimodal morphologies, which are inherently influenced by different pore types. Fractal characteristics of pore structure in fully water-saturated cores were captured through the T_(2) spectra, which were calculated using generalized fractal and multifractal theories. To augment the limited dataset of 36 cores, the synthetic minority oversampling technique was employed. Models for evaluating the T_(2) cut-off value were separately developed based on the classified T_(2) spectra, considering the number of peaks, and utilizing generalized fractal dimensions at the weight <0 and the singular intensity range. The underlying mechanism is that the singular intensity and generalized fractal dimensions at the weight <0 can detect the T_(2) spectral shift. However, the T_(2) spectral shift has negligible effects on multifractal spectrum function difference and generalized fractal dimensions at the weight >0. The primary objective of this work is to gain insights into the relationship between the kurtosis of the T_(2) spectrum and pore types, as well as to predict the T_(2) cut-off value of low-permeability rocks using machine learning and data augmentation techniques. 展开更多
关键词 Nuclear magnetic resonance Low-permeability porous media T_(2)cut-off value Fractal and multifractal Data augmentation Machine learning
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Medical and interventional therapy of Kasabach-Merritt phenomenon associated with Kaposiform hemangioendothelioma:A case report
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作者 Yan Zhao Ji Cheng 《Journal of Interventional Medicine》 2023年第3期130-133,共4页
An infant with Kasabach-Merritt Phenomenon(KMP)presented with a giant subcutaneous mass in the right lower limb,severe hypofibrinogenemia,and thrombocytopenia.Glucocorticoids,along with supportive treatments including... An infant with Kasabach-Merritt Phenomenon(KMP)presented with a giant subcutaneous mass in the right lower limb,severe hypofibrinogenemia,and thrombocytopenia.Glucocorticoids,along with supportive treatments including transfusion of blood products and clotting factors,were administered to reverse fatal disseminated intravascular coagulation and acute hemolysis.The glucocorticoid dose was tapered slowly,and sirolimus was added to treat the hemangiomas.The patient subsequently underwent interventional therapy.After 6 months of medical and interventional therapy,the patient was doing well with a normal platelet count,the tumor volume was markedly reduced,and the primary cutaneous lesion became pale pink.Currently,the patient remains on sirolimus,and no recurrence of thrombocytopenia or further growth of the mass was observed after six months of follow-up. 展开更多
关键词 Kasabach-Merritt phenomenon(KMP) Kaposiform hemangioendothelioma(KHE) SIROLIMUS Interventional therapy
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Anesthetic management of a patient with preoperative R-on-T phenomenon undergoing laparoscopic-assisted sigmoid colon resection:A case report
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作者 Xiao-Xi Li Yun-Feng Yao Hong-Yu Tan 《World Journal of Clinical Cases》 SCIE 2023年第9期2098-2103,共6页
BACKGROUND The R-on-T phenomenon is a malignant arrhythmia associated with potentially catastrophic consequences.It may initiate ventricular tachycardia or ventricular fibrillation,which can result in syncope or sudde... BACKGROUND The R-on-T phenomenon is a malignant arrhythmia associated with potentially catastrophic consequences.It may initiate ventricular tachycardia or ventricular fibrillation,which can result in syncope or sudden cardiac death.This manifestation poses a great challenge for anesthesiologists.However,it is rarely encountered in the perioperative setting.CASE SUMMARY We herein present a case in which the R-on-T phenomenon was incidentally revealed by 24-h Holter monitoring in a patient diagnosed with sigmoid colon cancer.Careful evaluation and treatment with mexiletine were carried out preoperatively under consultation with a cardiovascular specialist,and surgery was uneventfully performed under general anesthesia after thorough preparation.CONCLUSION Physicians should be vigilant about this infrequent but potentially fatal arrhythmia.Our experience suggests that the anesthetic process can be greatly optimized with careful preparation. 展开更多
关键词 R-on-T phenomenon Premature ventricular contraction Sigmoid colon cancer Sigmoid colon resection General anesthesia Case report
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Lipoprotein (a) Cut-Off in Chronic Kidney Disease Patients with a History of Cardiovascular Disease in Center Hospital University Souro SANOU, Burkina Faso
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作者 Ollo Da Aoua Semde +7 位作者 Arnaud Kouraogo Emmanuel Zongo Amidou Sawadogo Aristide Zongo Fatou Gueye Tall Souleymane Fofana Sanata Bamba Georges Anicet Ouedraogo 《Advances in Biological Chemistry》 2023年第6期228-235,共8页
Patients living with chronic kidney disease (CKD) are at high risk of cardiovascular events. Our aim in this study was to assess the cut-off value for lipoprotein (a) (Lp(a)) in CKD patients with a history of cardiova... Patients living with chronic kidney disease (CKD) are at high risk of cardiovascular events. Our aim in this study was to assess the cut-off value for lipoprotein (a) (Lp(a)) in CKD patients with a history of cardiovascular disease (CVD). This was a cross-sectional study. Variables including age, sex, history of CVD, body mass index and CKD stage, were collected during CKD patient’s first admission in the nephrology dialysis department. Blood samples were collected for quantitative determination of Lp(a) by immunoturbidimetric method. They were divided into two groups: CKD patients without history of CVD and CKD patients with history of CVD. Fisher’s exact test was used to assess associations with a significance level of 0.05%. Area under the curve (AUC) and new cut-off value for Lp(a) were identified by drawing Receiver Operating Characteristic (ROC) curve. A total of seventy CKD patients with median age of 43 years [minimum-maximum = 15 - 78 years] were included. Patients with history of CVD were 65.71% (46/70). New Lp(a) cut-off point in CKD patients with history of CVD was 66.50 nmol/L [sensitivity, 87.00%;specificity, 58.30%;AUC = 0.727;p = 0.000]. ROC curve demonstrated good performance of Lp(a) to screen CKD patients with history of CVD. Further research is needed to determine an LPA gene polymorphism’s contribution to increasing risk for CVD at each kidney disease stage. 展开更多
关键词 Lipoprotein (a) cut-off Chronic Kidney Disease Cardiovascular Disease
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当代大学生消极苦乐观的表征解析、疗愈理论与教育对策——以“摆烂”现象为例 被引量:3
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作者 张静 宋小洪 《江苏大学学报(社会科学版)》 2024年第3期116-124,共9页
苦乐观是人生观的重要组成部分,体现了个体对自我生存意义的探寻,而当前部分大学生的“摆烂”现象反映了其苦乐观的消极倾向。通过对当代大学生的“摆烂”现象进行分析,可以发现部分大学生在苦乐观方面存在以下表征:片面理解苦乐内涵与... 苦乐观是人生观的重要组成部分,体现了个体对自我生存意义的探寻,而当前部分大学生的“摆烂”现象反映了其苦乐观的消极倾向。通过对当代大学生的“摆烂”现象进行分析,可以发现部分大学生在苦乐观方面存在以下表征:片面理解苦乐内涵与关系的怀疑倾向,苦乐态度不端与情感消极为表征的颓废悲观倾向,苦乐信念缺乏与意志薄弱的精神虚无倾向以及苦乐动机功利与行为脱节的精致利己主义倾向。借助积极心理学相关理论探讨大学生苦乐观教育,有助于消解大学生“摆烂”症候,帮助大学生辩证对待人生苦乐矛盾,树立积极向上的苦乐观。 展开更多
关键词 当代大学生 “摆烂”现象 苦乐观教育 积极心理 表征解析 疗愈理论
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乙型肝炎病毒检测方法的现状研究
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作者 高飞 宁霄 +3 位作者 罗春媚 兰华林 王佳庆 周海卫 《标记免疫分析与临床》 CAS 2024年第7期1338-1343,共6页
HBV感染是我国最主要的传染性疾病之一,目前临床主要使用体外诊断试剂对该病毒进行准确快速的检测,体外诊断试剂盒的方法学主要包括:免疫学方法和分子生物学方法。本文通过PubMed(检索时限自2017年1月至2023年12月)和万方数据库(检索时... HBV感染是我国最主要的传染性疾病之一,目前临床主要使用体外诊断试剂对该病毒进行准确快速的检测,体外诊断试剂盒的方法学主要包括:免疫学方法和分子生物学方法。本文通过PubMed(检索时限自2017年1月至2023年12月)和万方数据库(检索时限自2017年1月至2023年12月)检索乙型肝炎病毒(hepatitis B virus,HBV)的检测方法、相关试剂盒的生产和临床应用的相关文献,详细列举最新检测方法的进展并比较不同方法学的优缺点,全面分析和讨论了我国目前乙型肝炎病毒检测的现状和研究进展。研究发现,我国HBV检测用商品化试剂盒的方法学分布存在集中现象,试剂盒的生产存在“东部多,西部少,大分散,小聚集”的特点。 展开更多
关键词 乙型肝炎病毒 检测方法 集中现象
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我国闭坑煤矿矿井水水质演化研究进展与展望
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作者 张海涛 许光泉 +4 位作者 陈晓晴 李旭 翟晓荣 李洋 李子璇 《煤炭学报》 EI CAS CSCD 北大核心 2024年第9期3944-3959,共16页
随着我国煤矿矿井关闭数量的逐渐增加,闭坑矿井水水质恶化和污染问题日益突出,准确掌握闭坑矿井水水质演化规律及机制,是目前闭坑矿山可持续绿色发展的重大科学难题,也是地下水污染有效防控和水资源合理开发利用的重要前提。在回顾关闭... 随着我国煤矿矿井关闭数量的逐渐增加,闭坑矿井水水质恶化和污染问题日益突出,准确掌握闭坑矿井水水质演化规律及机制,是目前闭坑矿山可持续绿色发展的重大科学难题,也是地下水污染有效防控和水资源合理开发利用的重要前提。在回顾关闭矿井发展历史的基础上,首先阐述了我国关闭矿井的分布情况,之后分别对闭坑矿井水水质特征、水质演化规律及水质演化的多场作用等方面展开综述,最后对我国闭坑矿井水水质研究中存在的关键问题和应用方向进行了展望。研究结果表明:①截至2023年底,我国关闭矿井的数量已经上升到13000多个,主要分布在山西、河南、河北、山东、江苏和安徽北部等地区;②我国部分闭坑矿井水的pH、矿化度、硫酸盐、氟化物和铁锰重金属等水质指标含量超过Ⅲ类水标准,其中酸性矿井水(pH<6.5)主要分布在云贵、鲁西、山西等地区,高矿化度矿井水(TDS>1000 mg/L)主要分布在鲁西、山西、河南、两淮、蒙东、宁东、新疆等地区,硫酸盐矿井水(硫酸盐质量浓度>250 mg/L)主要分布在云贵、鲁西、山西、蒙东、宁东、神东、新疆哈密等地区,氟化物矿井水(F质量浓度>1.0 mg/L)主要分布在两淮、山西、神东等地区,铁锰重金属矿井水(Fe质量浓度>0.3 mg/L、Mn质量浓度>0.1 mg/L)主要分布在云贵、鲁西、山西、蒙东等地区。③在闭坑矿井被完全淹没之前,其水质在空间上会出现明显的分层现象,即浅部的优质水层、中部的过渡水层和深部的劣质水层,这主要与矿井采掘空间分布、地温梯度和盐度等因素有关。④煤矿关闭后,矿井水水质的演变过程大致可分为3个阶段,第Ⅰ阶段为矿井水中典型污染物(硫酸盐和铁离子)质量浓度快速上升达并到峰值阶段,第Ⅱ阶段为污染物浓度快速下降阶段,第Ⅲ阶段为矿井水水质与邻近含水层地下水水质背景值相同并保持相对稳定阶段。⑤系统总结了我国闭坑矿井水动力场、水化学场、微生物场和温度场的研究进展,指出了闭坑矿井多相(水−岩−气−生)多场(水化学场−水动力场−微生物场−温度场)耦合作用机制的研究还不充分。⑥提出了我国闭坑矿井水水质演化问题的研究仍然面临着水质演化规律和水质演化机制不清楚等关键科学问题。 展开更多
关键词 闭坑矿井 水质演化 分层现象 水污染 多相多场耦合
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任务协作表示增强的要素及关系联合抽取模型
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作者 刘小明 王杭 +2 位作者 杨关 刘杰 曹梦远 《电子学报》 EI CAS CSCD 北大核心 2024年第6期1955-1962,共8页
对文本中诸如实体与关系、事件及其论元等要素及其特定关系的联合抽取是自然语言处理的一项关键任务.现有研究大多采用统一编码或参数共享的方式隐性处理任务间的交互,缺乏对任务之间特定关系的显式建模,从而限制模型充分利用任务间的... 对文本中诸如实体与关系、事件及其论元等要素及其特定关系的联合抽取是自然语言处理的一项关键任务.现有研究大多采用统一编码或参数共享的方式隐性处理任务间的交互,缺乏对任务之间特定关系的显式建模,从而限制模型充分利用任务间的关联信息并影响任务间的有效协同.为此,提出了一种基于任务协作表示增强的要素及关系联合抽取模型(Task-Collaboration Representation Enhanced model for joint extraction of elements and relationships,TCRE).该模型旨在从多个阶段处理任务间的特定关系,帮助子任务进行更细致的调节和优化,促进整体性能的提升.在三个关系抽取和一个事件抽取数据集上进行实验,TCRE在实体识别和关系提取任务上平均性能分别提高0.57%和0.77%,在触发词识别和论元角色分类任务上分别提高0.7%和1.4%.此外,TCRE还显示出在缓解“跷跷板现象”方面的作用. 展开更多
关键词 关系表示 联合抽取 任务协作 多任务学习 跷跷板现象
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复合润滑结构改善滑动导轨表面爬行现象研究
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作者 樊玉杰 陈俣哲 +4 位作者 郝梦杰 王苏扬 杜宇辰 夏晶 管小燕 《中国机械工程》 EI CAS CSCD 北大核心 2024年第10期1740-1746,1761,共8页
滑动导轨在低速重载时产生爬行现象,严重影响机床的加工精度。为了改善滑动导轨的爬行现象,对滑动导轨表面复合润滑结构的设计和摩擦力分阶段表征进行了研究。在激光烧蚀微织构的基础上,采用高温高压镶嵌法制备了复合润滑微织构,基于摩... 滑动导轨在低速重载时产生爬行现象,严重影响机床的加工精度。为了改善滑动导轨的爬行现象,对滑动导轨表面复合润滑结构的设计和摩擦力分阶段表征进行了研究。在激光烧蚀微织构的基础上,采用高温高压镶嵌法制备了复合润滑微织构,基于摩擦试验,提出了摩擦力分阶段表征方法,探索了不同复合润滑结构对各阶段摩擦力特征参数的影响规律,建立了复合润滑结构改善爬行现象的理论模型,找到抑制爬行现象性能最优的复合润滑结构。研究结果表明:表面微织构仅影响摩擦力的严重黏滑和爬升阶段,而复合润滑结构对整个启动阶段都有显著影响。填充二硫化钼(MoS 2)的正弦沟槽与六边形凹坑组合的多级复合润滑结构(SF-3)改善表面接触状态和抑制爬行现象的效果最好。与光滑表面(SS)试样相比,SF-3试样爬行时间缩短了72%,第Ⅰ阶段失稳力减小了69.83%,第Ⅱ阶段和第Ⅲ阶段的摩擦突跃力分别减小了75.91%和80.17%。 展开更多
关键词 滑动导轨 爬行现象 复合润滑结构 摩擦力
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直角凸壁面附近非对称位置的空泡动力学行为实验研究
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作者 席新铭 张程 +2 位作者 王笑语 李肖飞 张宇宁 《核科学与工程》 CAS CSCD 北大核心 2024年第3期602-612,共11页
空化破坏现象在核电厂中广泛存在。为了更深入地揭示空化破坏的机理,本文借助高速摄影实验系统,研究了直角凸壁面附近非对称位置空泡的动力学行为。具体分析了空泡的轮廓变形,形心的移动距离和方向,以及空泡射流的方向随着空泡与壁面相... 空化破坏现象在核电厂中广泛存在。为了更深入地揭示空化破坏的机理,本文借助高速摄影实验系统,研究了直角凸壁面附近非对称位置空泡的动力学行为。具体分析了空泡的轮廓变形,形心的移动距离和方向,以及空泡射流的方向随着空泡与壁面相对位置d、h的变化规律。本文主要结论如下:(1)空泡的变形与空泡和固体壁面的相对位置d、h有关。随着空泡与右壁面的距离d的增大,空泡的非对称性越来越弱。随着空泡与上壁面的距离h的增大,在整个空泡的动力学过程中空泡的非球形特征逐渐减弱。(2)在空泡的溃灭和再生长过程中,空泡形心会持续地向左下方移动,且形心向左移动的距离随着d和h的增大而明显减小。(3)当空泡与上壁面的距离h适当时,会产生明显的斜向左下方的射流现象,且射流方向角θ随着d的增大而增大。 展开更多
关键词 空泡动力学行为 直角凸壁面 空泡移动 射流现象
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circRNA CCND1对人肝癌HepG2细胞增殖、凋亡、侵袭和迁移的影响
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作者 董辉 顾铃毓 +1 位作者 俞梦楚 张旭 《中国现代医学杂志》 CAS 2024年第8期1-8,共8页
目的 探讨circRNA CCND1对人肝癌HepG2细胞增殖、凋亡、侵袭和迁移的影响。方法 采用荧光原位杂交(FISH)实验及实时荧光定量聚合酶链反应(qRT-PCR)检测circRNA CCND1在HepG2细胞及L02细胞中的表达情况;进一步干扰及过表达circRNA CCND1... 目的 探讨circRNA CCND1对人肝癌HepG2细胞增殖、凋亡、侵袭和迁移的影响。方法 采用荧光原位杂交(FISH)实验及实时荧光定量聚合酶链反应(qRT-PCR)检测circRNA CCND1在HepG2细胞及L02细胞中的表达情况;进一步干扰及过表达circRNA CCND1后,通过qRT-PCR检测circRNA CCND1在HepG2细胞中的表达情况,CCK-8法和EDU法检测HepG2细胞增殖情况,流式细胞术检测细胞凋亡、细胞周期,Transwell实验检测细胞侵袭情况,划痕实验检测细胞迁移情况。结果 HepG2细胞circRNA CCND1相对表达量较LO2细胞高(P <0.05)。Si-circRNA CCND1组circRNA CCND1相对表达量较Control组和Si-NC组下降(P <0.05),Oe-circRNA CCND1组较Control组和Oe-NC组升高(P <0.05)。各组细胞培养0、24、48、72和96 h后细胞增殖活性比较,经重复测量设计的方差分析,结果:(1)不同时间点细胞增殖活性比较,差异有统计学意义(P <0.05);(2)各组细胞增殖活性比较,差异有统计学意义(P <0.05);(3)各组细胞增殖活性变化趋势比较,差异有统计学意义(P <0.05)。与Control组及Si-NC组比较,Si-circRNA CCND1组细胞凋亡率升高(P <0.05),G_(0)/G_(1)期比值升高(P <0.05),S及G_(2)/M期比值下降(P <0.05);与Control组及Oe-NC组比较,OecircRNA CCND1组细胞凋亡率下降(P <0.05),G_(0)/G_(1)期比值下降(P <0.05),S及G_(2)/M期比值升高(P <0.05)。Si-circRNA CCND1组细胞侵袭数、细胞迁移数较Control组、Si-NC组少(P <0.05),Oe-circRNA CCND1组较Control组及Oe-NC组多(P <0.05)。结论 circRNA CCND1能够促进人肝癌细胞HepG2细胞增殖、侵袭和迁移,抑制细胞凋亡。 展开更多
关键词 肝肿瘤 circRNA CCND1 HEPG2 细胞生理学现象
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苦黄注射液预防抗结核药物导致的药物性肝损伤患者疗效研究
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作者 任浩 刘力伟 +3 位作者 施维 刘波 吴于青 吕芹 《实用肝脏病杂志》 CAS 2024年第1期56-59,共4页
目的本研究观察了应用苦黄注射液预防抗结核药物诱发药物性肝损伤(DILI)的作用,以避免不合理的抗痨中断治疗。方法2022年3月~2022年11月我院收治的97例肺结核患者,被随机分为试验组50例和对照组47例。所有患者均接受标准的2HREZ/4HR抗... 目的本研究观察了应用苦黄注射液预防抗结核药物诱发药物性肝损伤(DILI)的作用,以避免不合理的抗痨中断治疗。方法2022年3月~2022年11月我院收治的97例肺结核患者,被随机分为试验组50例和对照组47例。所有患者均接受标准的2HREZ/4HR抗结核治疗,试验组在此治疗的基础上加用苦黄注射液治疗8周。采用ELISA法检测血清白介素6(IL-6)和肿瘤坏死因子-α(TNF-α),采用放射免疫法检测血清血红素加氧酶(HO-1)和超氧化物歧化酶(SOD)水平。结果在治疗4周末,试验适应性肝损伤和DILI发生率分别为6.0%和2.0%,显著低于对照组的17.0%和8.5%(P<0.05),在治疗8周末,试验组适应性肝损伤和DILI发生率分别为6.0%和4.0%,显著低于对照组的21.3%和17.0%(P<0.05);在治疗8周末,试验组血清ALT、AST和TBIL水平分别为(28.4±23.4)U/L、(30.8±18.7)U/L和(12.9±7.3)μmol/L,显著低于对照组【分别为(53.1±33.1)U/L、(52.5±37.7)U/L和(20.1±10.9)μmol/L,P<0.05】;试验组血清HO-1和SOD水平分别为(200.3±14.0)U/L和(418.0±18.7)U/L,显著高于对照组【分别为(128.8±21.4)U/L和(318.0±15.1)U/L,P<0.05】,而血清IL-6和TNF-α水平分别为(11.4±1.9)ng/L和(9.3±1.8)ng/L,显著低于对照组【分别为(17.5±4.0)ng/L和(14.5±3.0)ng/L,P<0.05】。结论在抗痨开始时应用苦黄能够显著降低DILI的发生,尽可能地维持标准化抗结核治疗,且安全性良好。 展开更多
关键词 药物性肝损伤 肺结核 抗结核药物 适应现象 苦黄 预防
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预电离间隙击穿特性及其对中储开关击穿稳定性的影响
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作者 陈志强 王天驰 +5 位作者 王艺 郭帆 贾伟 谢霖燊 吴伟 陈伟 《现代应用物理》 2024年第3期68-74,共7页
紫外预电离中储开关是大型强电磁脉冲模拟装置的关键器件,中储开关预电离间隙击穿特性是影响开关性能的一个重要因素。在N_(2)气压为0.1~0.7 MPa的工作环境中,开展了预电离间隙的击穿特性及其对中储开关击穿稳定性影响的实验研究。预电... 紫外预电离中储开关是大型强电磁脉冲模拟装置的关键器件,中储开关预电离间隙击穿特性是影响开关性能的一个重要因素。在N_(2)气压为0.1~0.7 MPa的工作环境中,开展了预电离间隙的击穿特性及其对中储开关击穿稳定性影响的实验研究。预电离间隙的击穿特性实验结果表明,随着气压的增加,预电离间隙击穿电压呈现出不同的变化趋势:间隙距离较短时,击穿发生在预电离间隙钨针和铜电极之间的气体介质中,击穿电压呈现出渐进饱和的趋势;间隙距离较长时,低气压下的击穿发生在预电离间隙中,高气压条件下击穿发生在预电离电极的陶瓷套管表面气体介质中,此时击穿电压几乎不随气压发生变化。在电磁脉冲模拟装置中开展了预电离间隙击穿特性对紫外预电离中储开关击穿特性影响的实验,结果表明,当中储开关内部气压很高时,开关击穿分散性大于低气压区域。该结果可能与预电离间隙在高气压区域时击穿发生在陶瓷套管上有关,该现象导致预电离间隙击穿过早,使得预电离间隙击穿时刻与主间隙波形波峰时刻之间的时间差大于主间隙击穿的形成时延,从而增大了主间隙击穿电压的分散性。 展开更多
关键词 电磁脉冲模拟装置 紫外预电离开关 击穿 形成时延 饱和现象
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