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Grounded-source short offset transient electromagnetic method:Theory and applications in deep mineral exploration

Science China Earth Sciences 2025年第2期68卷 626-638页

作者： Guoqiang XUE xin WU Weiying CHEN Nannan zhou Key Laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

The Transient Electromagnetic(TEM)method is a critical geophysical technique for subsurface exploration of metal ore bodies,primarily utilizing either loop or grounded *** Long Offset Transient Electromagnetic(LOTEM)method employs a grounded-source transmitter,relying on a far-source observation mode and plane wave approximation for ***,LOTEM's far-source configuration weakens signal strength,and the plane wave approximation reduces precision,limiting effective detection depth to approximately 1000 m with a comprehensive error of about 15%.Recently,we have developed the grounded-source Short Offset Transient Electromagnetic(SOTEM)method,achieving greater detection depth and accuracy within the 500–2000 m depth range,a crucial interval for mineral resource *** study explores the theoretical framework,instrumentation,data processing,and field applications of *** on a point charge element model,SOTEM accurately computes surface wave effects in EM field calculations,optimized for near-source ***-power,high-resolution,wide-bandwidth exploration equipment and an advanced three-dimensional hybrid inversion technique were also developed to enhance the method's *** of SOTEM to the deep exploration of the zhou'an Ni-Cu-PGE deposit in Henan Province yielded high-resolution imaging of conductivity structures to about 2.5 km *** results,consistent with existing drill data,delineated mineralized ore bodies from surrounding formations,identified zones of mineralization potential,and suggested extensive resource prospects in the region.

关键词： Far-source observation Plane wave model approximation Grounded-source short-offset transient electromagnetic method Wide-bandwidth exploration equipment Three-dimensional hybrid inversion

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Significant improvement of machinability of C_(f)/SiC composites through matching laser scanning spacing and abrasive belt grain size

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Chinese Journal of Aeronautics 2025年第1期38卷 185-201页

作者： Guijian XIAO Zhengyu YANG Kun zhou Yi HE xin LI College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing 400044China State Key Laboratory of Mechanical Transmissions for Advanced Equipment Chongqing UniversityChongqing 400044China

To improve the application and service of C_(f)/SiC composites as advanced hightemperature structural materials,it is critical to achieve their high-efficiency and low-damage *** this study,the laser-ablating assisted grinding(LAAG)method was presented,and the connection of damage behavior and removal mechanism with laser and grinding processes was *** results demonstrated that the surface of C_(f)/SiC composites after laser ablation was covered with a substantial number of loose oxides primarily composed of *** ablating process,grinding parameter and abrasive belt selection have a significant impact on the machining *** fabricating an ablative layer with small laser scanning spacing,and selecting small abrasive grains and feed rate during grinding,the machinability was improved and a relatively lowerdamage grinding surface could be *** the optimal combination of process parameters,the grinding force and temperature of LAAG could be reduced by up to 85%and 35%,*** this case,the subsurface damage of C_(f)/SiC composites occurred only in the form of microcracks rather large-scale fracture,and the formation of interface debonding and matrix cracking was significantly ***,the grinding chips were mostly shown as micron-sized powders,indicating that the removal mechanism of C_(f)/SiC composites was primarily the microfractured and attrition wear of laser-ablated layer.

关键词： Ceramic matrix composites Laser ablating Grinding Material removal Fracture damage

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Gradient maturation experiment on hairs implies taphonomic changes in fossil hairs

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Science China Earth Sciences 2025年第1期68卷 62-73页

作者： xin LI Yibo zhou Tao ZHAO xingjian HE Yanhong PAN State Key Laboratory for Mineral Deposits Research Center for Critical Earth Material CyclingCentre for Research and Education on Biological Evolution and Environment and Frontiers ScienceSchool of Earth Sciences and EngineeringNanjing UniversityNanjing210023China Institute of Palaeontology Yunnan Key Laboratory of Earth System ScienceYunnan Key Laboratory for PalaeobiologyYunnan UniversityKunming650500China

Mammalian hair,as a key feature related to endothermy,physical protection,and camouflage,has a long geohistorical record that dates back even to the ***,the limited information on the taphonomy of hair hinders the understanding of its evolutionary significance in deep *** address this,we conducted taphonomic experiments to simulate the transformation process of black *** changes in the morphological structure,microscopic characteristics,and chemical composition of hair during the simulated fossilization process were documented by scanning electron microscopy,Fourier transform infrared(FTIR)spectroscopy,and Raman *** results revealed that damage to the morphology of hair began at a mild temperature(150–175℃),and hair transformed into a fluid-like mass at a relatively high temperature(200℃).In addition,the morphological structure of melanosomes had relatively greater preservation potential than keratins did,and the microscopic features of melanosomes were persistently *** Raman and FTIR spectra indicated that the characteristic melanin and keratin peaks changed as the temperature *** the chemical signals were not lost completely,the variations in the characteristic amide bands in the FTIR spectra indicate that the keratins severely degraded at high temperatures(>200℃),whereas the characteristic melanin bands in the Raman spectra suggested that melanin signals were still recognizable,even at high temperatures(>200℃).These results were confirmed by principal component analysis(PCA)and principal component analysis linear discriminant analysis(PCA–LDA).In addition,the Raman signals of all the samples in the simulated experiments were distinguished from the signals of common geological carbonaceous materials(humic acid),which suggested that Raman spectroscopy can be used to detect melanin in fossils.

关键词： Mammalian hair Melanin Keratin Fossilization Experimental taphonomy

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EFFECT OF OPERATING CONDITIONS ON THE SELECTIVITY TO α-OLEFIN IN FISCHER-TROPSCH SYNTHESIS

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Journal of Energy Chemistry 1995年第1期 59-65页

作者： LIU Zhong-wen ZHANG Zhi-xin zhou Jing-LaiInstitute of Cual Chermistry, Academa Sinica Taiyuan, Shanxi 030001 To whom correspondence should be addressed.

The effect of operating conditions on the O/P ratios of hydrocarbons produced from FTS over Fe/Cu/K catalyst was studied in a continuously stirring tank reactor (CSTR, Autoclave Engineers) under conditions of T= 515 -542 K, GHSV = 576-906 h-1 and H2/CO ratio= 1. 12 to 3.97. The O/P ratios of hydrocarbons with different carbon numbers may increase, decrease or keep constant with the increase of reaction temperature, GHSV and H2/CO ratio in reactor, respectively. The O/P ratios decrease with the increase of carbon numbers of hydrocarbons and the effect of operating conditions on the O/P ratios trends to decrease with the increase of carbon numbers from three to fifteen. The ratio of ethylene to ethane is always very low and almost independent of the change of operating conditions which indicates that the ethylene may participate in the process of chain growth.

关键词： Fischer-Tropsch synthesis selectivity α-olefin to n-paraffin ratio

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Eosinophilia and clonorchiasis presenting as fever of unknown origin in adult patients

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World Journal of Emergency Medicine 2025年第1期16卷 91-93页

作者： Jie Zhong xin zhou Wei Gu Department of Emergency Medicine Chuiyangliu HospitalBeijing 100022China

Fever of unknown origin(FUO)is recognized as fever with uncertain diagnosis despite three days of hospital admission or three or more outpatient visits.[1]Acute liver fluke infection is characterized by fever,right upper quadrant pain,hepatomegaly,jaundice,and peripheral blood *** contrast,chronic liver fluke infection is asymptomatic in its early stage,but can easily progress to cirrhosis,cancer,or bile duct cancer *** diagnosis of clonorchiasis is particularly challenging in non-endemic *** herein report an unusual case of liver fluke infection in a patient who presented with FUO and eosinophilia.A 38-year-old male was admitted to our hospital with a history of intermittent and recurrent fever for over 10 d and a history of sudden abdominal pain for1 *** had no other medical *** than 10d ago,he visited our emergency department because of FUO,with his body temperature reaching 39.7℃,and he had no other symptoms at that *** and radiological examinations revealed:white blood cell(WBC)counts,10.9×10^(9)/L;neutrophil percentage,84.5%;eosinophil percentage,3.1%;C-reactive protein(CRP),141 mg/L;liver and kidney function,normal;influenza virus,negative;urine and stool tests,normal;and chest computed tomography(CT)findings,*** fever subsided after 1 week of anti-infective treatment with *** tests revealed the following results:WBC,15.0×10^(9)/L;neutrophil percentage,70.0%;eosinophil percentage,16.8%;and CRP,122 mg/*** antimicrobial treatment was then discontinued.

关键词： fever diagnosis admitted

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A robust statistical prediction model for late-summer heavy precipitation days in North China

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Science China Earth Sciences 2025年第1期68卷 158-171页

作者： Shunli JIANG Tingting HAN xin zhou Huijun WANG Zhicong YIN Xiaolei SONG Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of Meteorological Disaster Ministry of EducationNanjing University for Information Science and TechnologyNanjing210044China Nansen-Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai519080China

Recently,heavy precipitation(HP)events have occurred frequently in North China(NC),causing devastating economic losses and human ***,the short-term climate prediction of HP is quite *** year-to-year increment(DY)method and sliding correlations,we developed a robust seasonal prediction model for late-summer HP days(HPDs)in NC during 1982–2022,utilizing three independent predictors—February sea surface temperature(SST)in the Indian Ocean(SST_IO),February snow depth over North Asia(SDE_NA),and May melted snow depth in NC(MSDE_NC).The SST_IO anomalies affect NC's precipitation through the Pacific-Japan *** SDE_NA anomalies are associated with East Asian anomalous anticyclone by southeastern propagation of Rossby wave at *** MSDE_NC anomalies are followed by vertical motion and moisture anomalies in situ and thereby cause precipitation *** prediction model can well simulate the variations of the HPDs,with a correlation coefficient(CC)of 0.81(0.65)between the observed and predicted HPDs_DY(HPDs_anomaly).The percentage with the same sign for 15 extreme HPDs_anomaly years(PSSE)is 100%.Moreover,in the cross-validation test during 1982–2022,the PSSE for HPDs_anomaly is as high as 100%,along with a low rootmean-square error of *** independent hindcasts during 2013–2022,the CC between the observed and predicted HPDs_DY(HPDs_anomaly)is 0.93(0.83),together with high Nash-Sutcliffe efficiency(0.82)and agreement index(0.89).Specifically,the predictions are broadly consistent with the observations for 2015,2016,2017,2021,and 2022,reflecting excellent performance of this prediction model of HPDs in NC.

关键词： Heavy precipitation at North China Year-to-year increment approach Robust seasonal prediction Sea surface temperature Snow depth

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Radical dehydroxymethylative fluorination of aliphatic primary alcohols and diverse functionalization ofα-fluoroimides via BF_(3)·OEt_(2)-catalyzed C-F bond activation

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Chinese Chemical Letters 2025年第1期36卷 239-243页

作者： Peng Wang Jianjun Wang Ni Song xin zhou Ming Li Molecular Synthesis Center Key Laboratory of Marine MedicineChinese Ministry of EducationSchool of Medicine and PharmacyOcean University of ChinaQingdao 266003China Laboratory for Marine Drugs and Bioproducts Pilot National Laboratory for Marine Science and TechnologyQingdao 266237China

Ag_(2)CO_(3)-promoted dehydroxymethylative fluorination of aliphatic alcohols has been achieved with Selectfluor as both oxidant and fluorine *** reaction involvesβ-fragmentation of primary alkoxy radicals,followed by the fluorination of the resulting C-centered radical *** transformation proceeds under mild reaction conditions and exhibits a broad substrate scope,thus opening up a new entrance to the synthesis of fluorinated constructs includingα-fluoroimides and 1-fluoroalkyl benzoates as well as secondary and tertiary alkyl fluorides like versatile 2-fluoro-2-alkyl 1,3-propandiol *** divergent functionalization of the obtainedα-fluoroimides enables an efficient access to amine derivatives through C-F bond activation under the action of BF_(3)·OEt_(2).

关键词： Dehydroxymethylative fluorination Alkoxy radicals β-Fragmentation Silver catalysis C-F Bond activation

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Exploring economic viable species via assessing a tropic-specific microalgal collection

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Journal of Oceanology and Limnology 2025年第1期43卷 210-218页

作者： Chen MA Ni WANG Yi xin Qinhua GAN wenxu zhou Yandu LU State Key Laboratory of Marine Resource Utilization in South China Sea School of Marine Biology and FisheriesHainan UniversityHaikou 570228China Hainan Engineering&Research Center of Marine Bioactives and Bioproducts Haikou 570228China Haikou Innovation Platform for Research&Utilization of Algal Bioresource Hainan UniversityHaikou 570228China Hainan Provincial Key Laboratory of Tropical Hydrobiotechnology Hainan UniversityHaikou 570228China

Locations around the equator provide unique habitats for microalgae presumably with exceptional *** develop microalga-derived product systems,we previously created a(sub)tropical microalgal *** this study,two Chlorella strains(MEM176 and MEM193),adaptive to typical tropical climate,were isolated from the *** production performance was evaluated where both strains showed a robust growth in high temperatures and light ***,the strains MEM176 and MEM193 produced 503.6-mg/(L·d)and 411.3-mg/(L·d)biomass,respectively,with high contents of *** commercial and nutritional values were emphasized by amino acid compositions(e.g.,proline,valine,and phenylalanine).Particularly,higher amounts of proline were revealed in MEM176(47.9 mg/g dry biomass(DW))and MEM193(47.9 and 59.2 mg/g DW)than available commercial *** with MEM193,MEM176 produced 129.7%more lipids in which unsaturated fatty acids(particularly linoleic acid andα-linolenic acid)account for 65%of the total ***,it is promising to explore the potential of these Chlorella strains as food additives via outdoor cultivation in tropical area,notably MEM176 that exhibits superiority as sources of essential amino acids and valuable fatty acids.

关键词： Chlorella tropical species food additive microalga

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Tandem asymmetric dearomatized functionalization reaction of phenols with Evans-ynamides enabled by divergent electrophiles

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Science China Chemistry 2025年第2期68卷 649-660页

作者： Ying-Qi Zhang Gan-Lu Qian Yun Liu Jia-Hui Li xin Hong zhou Xu Bo zhou Long-Wu Ye State Key Laboratory of Physical Chemistry of Solid Surfaces Key Laboratory of Chemical Biology of Fujian Provinceand College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Center of Chemistry for Frontier Technologies Department of ChemistryState Key Laboratory of Clean Energy UtilizationZhejiang UniversityHangzhou 310027China Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy School of PharmacyXuzhou Medical UniversityXuzhou 221004China State Key Laboratory of Elemento-Organic Chemistry Nankai UniversityTianjin 300071China State Key Laboratory of Organometallic Chemistry Chinese Academy of SciencesShanghai 200032China

Herein,we disclose a highly regio-/chemoselective tandem asymmetric dearomatized halofunctionalization reaction of phenoltethered ynamides with diverse electrophilic halogenation sources in a catalyst-free manner for the practical and rapid assembly of a series of halogenated spirocyclic ***,the related dearomatized selenation and protonation are also achieved,affording the corresponding selenated and protonated spirocycles in high ***,the enantioselectivities of these products can be perfectly induced by Evans auxiliaries(99%ees).Significantly,this protocol not only represents the first tandem asymmetric halofunctionalization reaction of phenol derivatives,but also constitutes the first asymmetric halogenation/selenation of *** calculations indicate a remote induction model of Evans chiral auxiliary-attached keteniminium.

关键词： alkynes cyclization dearomatization Evans chiral auxiliary spirocycles

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Least Square Estimation for Multiple Functional Linear Model with Autoregressive Errors

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Acta Mathematicae Applicatae Sinica 2025年第1期41卷 84-98页

作者： Meng WANG Ming-liang SHU Jian-jun zhou Si-xin WU Min CHEN School of Management University of Science and Technology of ChinaHefei 230026China Academy of Mathematics and System Science Chinese Academy of SciencesBeijing 100190China Yunnan Key Laboratory of Statistical Modeling and Data Analysis Yunnan UniversityKunming 650091China

As an extension of linear regression in functional data analysis, functional linear regression has been studied by many researchers and applied in various fields. However, in many cases, data is collected sequentially over time, for example the financial series, so it is necessary to consider the autocorrelated structure of errors in functional regression background. To this end, this paper considers a multiple functional linear model with autoregressive errors. Based on the functional principal component analysis, we apply the least square procedure to estimate the functional coefficients and autoregression coefficients. Under some regular conditions, we establish the asymptotic properties of the proposed estimators. A simulation study is conducted to investigate the finite sample performance of our estimators. A real example on China's weather data is applied to illustrate the validity of our model.

关键词： multiple functional linear model autoregressive errors principal component analysis consistency

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