检索结果-南通市图书馆

Study on the tribological properties of metal rolling bearing under lubrication with diketone lubricants

Science China(Technological sciences) 2024年第7期67卷 2003-2017页

作者： DU ShaoNan ZHANG ChenHui LUO Zhi State Key laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Beijing National laboratory of Molecular sciences CAS Key Laboratory of Engineering PlasticsInstitute of ChemistryChinese Academy of SciencesBeijing 100190China

In this article, 1-(4-ethylphenyl)-nonane-1,3-dione(0206) was prepared by Claisen condensation. By mixing 0206, chelate, and base oil in a ratio of 3.2:4.8:2, a diketone lubricant(PAO=14(20%)) that can achieve superlubricity was prepared and applied to bearing lubrication experiments. The experimental results show that when the bearing was lubricated by base oil, the friction coefficient(COF) and temperature rise decreased with the decrease of the viscosity of PAO. When PAO=14(20%) was used as the lubricant, the COF of the bearing was the lowest(0.001), and the wear morphology was comparable to that of the bearing lubricated with commercial lubricant. Compared with the base oil with the same viscosity, it is found that the COF and temperature rise of the bearing lubricated by PAO=14(20%) were lower under any experimental conditions. And when the amount of lubricant added was 10 μL, the COF of the bearing lubricated by PAO=14(20%) reached a very low value(0.0004).Bearing ball surface analysis identified the formation of diketone adsorption films. Combined with the previous PAO=14(20%)superlubricity mechanism, it was considered that the occurrence of tribochemical reaction and the bearing effect of chelates were the main reasons for the existence of ultra-low friction coefficient and low wear. In addition, when there were polar molecules in the lubricant, they were adsorbed on the metal surface through tribochemical reactions, resulting in many irregular pits on the surface.

关键词： superlubricity diketone chelate tribochemical recations bearing lubrication

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Advances in theoretical calculations of organic thermoelectric materials

引用

Chinese Chemical Letters 2024年第8期35卷 112-127页

作者： Shaohua Zhang Liyao Liu Yingqiao Ma Chong-an Di Beijing National laboratory for Molecular sciences CAS Key Laboratory of Organic SolidsInstitute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical sciences University of Chinese Academy of SciencesBeijing 100049China

Organic thermoelectric(OTE)materials and devices have garnered significant attention in the past decade for flexible and wearable *** to the numerous combinations of different backbones,side chains,and functional groups for polymer molecules,further efficient developments of high perfor-mance OTEs rely on reverse and rational molecular design as well as fundamental understanding to the structure-property relationship,which both require precise theoretical ***,many theo-retical efforts and progresses have been made to predict TE properties and develop high performance OTE ***,we present first the general methods and principles for OTE theoretical ***,the latest theoretical advances regarding the effects of molecular design,chemical dop-ing,ambipolar charge transport etc.,to TE conversion are carefully *** theoretical advances not only significantly deepen the fundamental understanding of OTEs,but also provide precise guidance to the molecular design of OTE ***,we propose several perspectives for future theoretical investigations of OTEs.

关键词： Organic thermoelectricity Theoretical study Organic semiconductor Structure-property relation Single-molecular device

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Combination of diketone and PAO to achieve macroscale oil-based superlubricity at relative high contact pressures

引用

Friction 2024年第5期12卷 869-883页

作者： Shaonan DU Chenhui ZHANG Zhi LUO State Key laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing100084China Beijing National laboratory of Molecular sciences CAS Key Laboratory of Engineering PlasticsInstitute of ChemistryChinese Academy of SciencesBeijing100190China

1-(4-ethylphenyl)-nonane-1,3-dione(0206)is an oil-soluble liquid molecule with rod-like *** this study,the chelate(0206-Fe)with octahedral structure was prepared by the reaction of ferric chloride and 1,*** experimental results show that when using 0206 and a mixed solution containing 60%0206-Fe and 40%0206(0206-Fe(60%))as lubricants of the steel friction pairs,superlubricity can be achieved(0.007,0.006).But their wear scar diameters(WSD)were very large(532µm,370µm),which resulted in the pressure of only 44.3 and 61.8 MPa in the contact areas of the friction *** 0206-Fe(60%)was mixed with PAO6,it was found that the friction coefficient(COF)decreased with increase of 0206-Fe(60%)in the *** the ratio of 0206-Fe(60%)to PAO6 was 8:2(PAO6(20%)),it exhibited better comprehensive tribological properties(232.3 MPa).Subsequent studies have shown that reducing the viscosity of the base oil in the mixed solution helped to reduce COF and increased *** the COF,contact pressure,and running-in time,it was found that the mixed lubricant(Oil3(20%))prepared by the base oil with a viscosity of 19.7 mPa·s(Oil3)and 0206-Fe(60%)exhibited the best tribological properties(0.007,161.4 MPa,3,100 s).

关键词： diketone oil-based lubricants chelate superlubricity

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Interplay between Microscopic Structures and Macroscopic Viscoelastic Properties of Polyampholyte Gels

引用

Chinese Journal of Polymer Science 2024年第9期42卷 1360-1367,I0008页

作者： You-Cai Xue Yi-Ming Yang Di Jia Beijing National laboratory for Molecular sciences Laboratory of Polymer Physics and ChemistryInstitute of ChemistryChinese Academy of SciencesBeijing100190China University of Chinese Academy of sciences Beijing100049China

Polyampholyte gels,which have hierarchical structures,exhibit excellent self-healing properties and have great promise for biomaterials and *** investigated the relationship between microscopic structures and macroscopic viscoelastic properties of polyampholyte gels and found three factors influencing their viscoelastic properties,including the chemical crosslinking bonds,topological entanglements controlled by monomer concentration,and the ionic *** strength plays a major role on the strength of ionic bonds.A crossover point of elastic modulus and loss modulus was observed in the dynamic frequency sweeps at low monomer concentration or low chemical crosslinking density for gels with intermediate strength of ionic *** solid-liquid transition signaled by the crossover point is a typical feature of dynamic associated gels,representing the dynamical association-dissociation of the ionic bonds and full relaxation of the topological entanglements in the gel *** the crossover point disappears when the ionic bonds are too weak or too strong to form“permanent”***,in the non-linear yielding measurement,gels with intermediate strength of the ionic bonds are ductile and yield at very large shear strain due to the self-healing properties and the dynamic association-dissociation of the ionic *** the self-healing properties disappear when the ionic bond strength is too weak or too *** work reveals the mechanism of how the dynamic association-dissociation of ionic bonds influences both the linear and non-linear viscoelastic properties of the polyampholyte gels.

关键词： Polyampholyte gel Ionic bond Topological entanglement Self-healing Hierarchical structure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effect of red clover isoflavones on hormone, immune, inflammatory,and plasma biochemistry in lactating dairy cows

引用

Animal Nutrition 2024年第1期16卷 306-312页

作者： Shiqi Zhang Xiaoyin Zhang Zhanbo Xiong Kexin Li Yuan Gao Ying Bu Nan Zheng Shengguo Zhao Jiaqi Wang State Key laboratory of Animal Nutrition Institute of Animal Sciences Chinese Academy of Agricultural Sciences

This study was to conducted to investigate the effect of red clover isoflavones on the health indicated by immune status and blood biochemistry in dairy cows. Sixty-eight healthy Holstein lactating cows were randomly divided into four treatments(n = 17 per treatment) from 5 blocks according to milk yield using a randomized complete block design. No initial differences in parity(2.13 ± 1.21), days in milk(165 ± 21 d), and milk yield(33.93 ± 3.81 kg/d) between groups. Cows were fed the basal diet supplemented with 0, 2, 4, or 8 g/kg red clover extract(RCE) in diet(dry matter based). Feeding, refusal feed weights, and milk yield were recorded three consecutive days in weeks 0, 4, 8, and 12. Blood was collected from the tail vein of the cows on the last day of weeks 4, 8 and 12, 1 h after the morning feeding,and analyzed for hormones, immunoglobulins, inflammatory markers, and markers of liver and kidney activities. The dry matter intake was significantly decreased by 3.7% in the 8 g/kg group(P 0.05). These results recommend the supplementation of RCE at a level from 2 to4 g/kg DM.

关键词： Dairy cow Red clover isoflavone Immunity Anti-inflammatory

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

The romance of replication:Hand in hand,from dawn to dusk

引用

Science Bulletin 2024年第16期69卷 2474-2475页

作者： Runze Ma Zijing Liu Bing Zhu National laboratory of Biomacromolecules Institute of BiophysicsChinese Academy of SciencesBeijing 100101China Key laboratory of Epigenetic Regulation and Intervention Chinese Academy of SciencesBeijing 100101China New Cornerstone Science laboratory Institute of BiophysicsChinese Academy of SciencesBeijing 100101China

Faithful DNA duplication is the fundamental event for all life *** to replicate the whole genome quickly and efficiently is a challenge that must be faced within every S phase of the cell cycle[1].Considering the increased size and complexity of mammalian genomes,it is plausible that the regulation of DNA replication is more intricate in *** of thousands of replication origins have been identified throughout mammalian genomes[2].Whether replication forks originated from different origins cooperate during replication is a long-term concern in the field.

关键词： originated field. replication

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

An unprecedented synthesis of axially chiral biaryls by rearrangement and aromatization of carbocations with central-to-axial conversion of chirality

引用

Science China Chemistry 2024年第9期67卷 2998-3003页

作者： Qi Liu Xue-Dong Li Liang Cheng Li Liu Beijing National laboratory for Molecular sciences(BNLMS) CAS Key Laboratory of Molecular Recognition and FunctionCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of sciences Beijing 100049China

The central-to-axial chirality conversion represents a fascinating class of chemical processes consisting of the destruction of stereogenic centers and the simultaneous installation of axial chiral elements,which provides efficient methods for the preparation of axially chiral ***,developing catalytic asymmetric approaches for constructing these central chirality precursors and the efficient central-to-axial chirality conversion remains a challenge due to the requirement of aromatization or elimination *** this work,we have developed an unprecedented enantioselective intramolecular FriedelCrafts alkylation with unactivated-ketone carbonyls from which a chiral tertiary alcohol was generated with high efficiency and excellent *** addition,the central-to-axial chirality conversion strategy has been successfully applied to the synthesis of enantioenriched biaryls via a less-explored carbocation-initiated rearrangement and aromatization under the promotion of Lewis *** methodology provided a straightforward and sustainable access to a broad range of biaryl-2-carboxylic acid and in excellent yields(up to 92%)and excellent central-to-axial chirality conversion(up to 99%conversion percentage).This work could be a great model for developing new methods for synthesizing axially chiral biaryls and a general protocol for the rearrangement and aromatization of carbocations for further functionalization.

关键词： br?nsted acid catalysis desymmetrization phosphoric acid axially chiral biaryls central-to-axial conversion

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Insights of carbon reduction practices from Winter Olympics 2022

引用

Science Bulletin 2024年第13期69卷 2034-2037页

作者： Xiaoyong Liao Shuai Zhong Jie Huang Zhu Liu Ayman Elshkaki You Li Lei Shen Yingli He Li An Yidong Zhu Wenhao Sun Tao Liang Jiaoe Wang Jinwei Dong Key laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Key laboratory for Resources Use and Environmental Remediation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Key laboratory of Regional Sustainable Development Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of sciences Beijing 100049China department of Earth System Science Tsinghua UniversityBeijing 100084China

Concerns about the carbon emissions of mega-events revolve,mainly due to the impactful demonstration effects they ***,accurate monitoring of these emissions is crucial during such events[1].The Olympic and Paralympic Winter Games Beijing 2022(hereinafter“Winter Olympics 2022”)are recognized as the first Games to pay close attention to a wide range of emissions associated with all stages of the *** of emerging carbon reduction technologies,such as low-carbon materials and technologies,have shown promising effects on efforts to achieve carbon neutrality[2].The impacts of individual measures,such as Olympic infrastructure construction.

关键词： Winter emissions carbon

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Bias distribution and regulation in photoelectrochemical overall water-splitting cells

引用

National Science Review 2024年第4期11卷 141-150页

作者： Kun Dang Siqin Liu Lei Wu Daojian Tang Jing Xue Jiaming Wang Hongwei Ji Chuncheng Chen Yuchao Zhang Jincai Zhao Key laboratory of Photochemistry CAS ResearchEducation Center for Excellence in Molecular Sciences Institute of Chemistry Chinese Academy of Sciences University of Chinese Academy of sciences

The water oxidation half-reaction at anodes is always considered the rate-limiting step of overall water splitting（OWS）,but the actual bias distribution between photoanodes and cathodes of photoelectro chemical（PEC） OWS cells has not been investigated *** this work,we find that,for PEC cells consisting of photoanodes（nickel-modified n-Si [Ni/n-Si] and α-Fe2O3） with low photovoltage(Vph 1V,the bias required for cathode activation can be significantly reduced,exhibiting a kinetics-controlled *** investigations show that the bias distribution can be regulated by tuning the electrolyte pH and using alternative half-reaction ***,a volcano plot is presented for the rational design of the overall reactions and unbiased PEC *** by this,an unbiased PEC cell consisting of a simple Ni/n-Si photoanode and Pt cathode is assembled,delivering a photo current density of 5.3±0.2 mA cm-2.

关键词： photoelectrochemistry overall reaction cell bias distribution photoanode water splitting

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Quantitative estimation of global mean precipitation throughout the Phanerozoic era

引用

Science China Earth sciences 2024年第5期67卷 1616-1624页

作者： Xiujuan BAO Yongyun HU laboratory for Climate and Ocean-Atmospheric Studies Department of Atmospheric and Oceanic SciencesSchool of PhysicsPeking UniversityBeijing 100871China

Quantitatively estimating the global mean precipitation(GMP)throughout Earth's history is crucial for enhancing our understanding of long-term climate evolution and the hydrological ***,currently there is no established methodology for estimating global mean ***,we present the first study that estimates GMP in the Phanerozoic *** relationship between GMP and global mean surface temperature(GMST)is investigated by analyzing data from 23 models in the Coupled Model Intercomparison Project phase 6(CMIP6).The result reveals consistent and significant impact of temperature on precipitation,with a sensitivity range of 2–3%K^(-1).Additionally,we propose a method for accessing latitudinal variations in precipitation caused by land area distributions and paleo-Koppen climatic *** climatic belts are determined based on geological indicators such as coals,evaporites,and glacial *** GMP is thus quantitatively estimated by combining variations in GMST,land area distributions,and paleo-koppen climatic belts,spanning from 540 Ma to the present *** quantitative GMP curve demonstrates fluctuations in GMP about 500 mm yr^(-1),with values ranging from 948 to1442 mm yr-1over the Phanerozoic *** curve aligns closely with findings derived from numerical *** presented paleoprecipitation variations facilitate a more comprehensive understanding of the interconnected geological and paleoclimatic developments.

关键词： Paleoprecipitation Paleoclimate K?ppen climatic belts Global mean precipitation Hydrological cycle

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：