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High-Tc Nearly-Free-Electron Superconductivity in Quaternary Hydrides under Ambient Pressure 认领 引用
1
作者 Bin Li Zhisi Cao +4 位作者 Junjie Zhai Mian Wu Ding Chi Shengli Liu Jian Sun 《Chinese Physics Letters》 SCIE EI CAS CSCD 2026年第1期265-296,共32页
We report a theoretical investigation into superconductivity within the MAXH6 quaternary hydride system using first-principles calculations,where M and A denote alkali and alkaline earth elements,respectively,and X... We report a theoretical investigation into superconductivity within the MAXH6 quaternary hydride system using first-principles calculations,where M and A denote alkali and alkaline earth elements,respectively,and X represents transition metal elements.Systematic analysis of electronic band structures,phonon dispersions,and electron-phonon coupling reveals that substitution of MA binary metal combinations and X metal atoms can create favorable conditions for superconductivity.Mapping of superconducting critical temperatures,combined with dynamical stability analysis through phonon calculations,identifies ten superconducting candidates at ambient pressure.Among these,LiNaAgH6 exhibits nearly-free-electron behavior reminiscent of monovalent electron superconductors.It demonstrates exceptional superconducting properties with electron–phonon coupling λ=2.707,which yields a superconducting transition temperature Tc of 206.4 K using the Allen–Dynes formula.Its structural analogs MgNaPdH6,LiMgPdH6,LiMgAgH6,LiMgAuH6 all exhibit superconducting transition temperatures above 110 K.These findings advance our fundamental understanding of superconductivity in quaternary hydrides and provide guidance for rational design of new high-temperature superconducting materials. 展开更多
关键词 alkali alkaline earth elementsrespectivelyand hydride system quaternary hydrides transition metal analysis electronic band structuresphonon dispersionsand high tcsuperconductivity first principles calculations electron phonon coupling
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Conquering high-temperature acidic corrosion with a molecular anvil:A robust pyridinium quaternary ammonium salt 认领 引用
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作者 Hui-Ling Su Zhi-Kun Wang +9 位作者 Lei Yu Xu-Peng Li Jia-Qi Feng Shi-Dong Xia Zi-Xiao Chen Mian-Tuo Li Si-Yu Liu Yu Fu Jing-Yue Wang Song-Qing Hu 《Petroleum Science》 SCIE EI CAS CSCD 2026年第6期3587-3601,共15页
Achieving robust corrosion protection under extreme acidic and high-temperature conditions remains a formidable challenge in the oil and gas industry.In this work,we report a molecularly engineered corrosion inhibitor... Achieving robust corrosion protection under extreme acidic and high-temperature conditions remains a formidable challenge in the oil and gas industry.In this work,we report a molecularly engineered corrosion inhibitor—a long-carbon-chain-functionalized quaternized pyridine derivative(Q4-APC12)—that has exceptional protection for N80 steel in highly aggressive environments at 500 mg/L.The inhibitor achieves corrosion rates of 0.029 g/(m2·h)(99.86%inhibition efficiency)in 1 mol/L(3.6%)HCl solution at 303 K and 7.29 g/(m2·h)(99.21%inhibition efficiency)in 15%HCl solution at 363 K.The superior perfo rmance is attributed to a rationally designed syne rgistic mechanism.X-ray photoelectron spectroscopy(XPS)and density functional theory(DFT)analyses confirm co-adsorption through electrostatic interaction of the quaternary ammonium group(N+peak at 402.5 eV)and chemical coordination via the pyridinic nitrogen(N-Fe peak at 399.8 eV),while the dodecyl chain enhances electrondonating ability(elevated HOMO energy at-7.57 eV)and strengthens interfacial adhesion(adsorption energy of-2.62 eV).At the morphological level,all-atom molecular dynamics(MD)simulations reveal that the alkyl chain drives the spontaneous self-assembly of a highly compact and stable bilayer film on the steel surface.This structured film significantly reduces surface roughness to 0.54μm under aggressive conditions and acts as an effective hydrophobic barrier against corrosive species.By correlating macro-scale performance with atomic-scale interactions,this study provides deep molecularlevel insights into the multi-mode adsorption and film formation,offering a robust strategy for designing high-performance inhibitors for demanding oilfield environments. 展开更多
关键词 Quaternary ammonium Long alkyl chains High temperatures Strong acid Corrosion protection
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Quaternary ammonium and copper phthalocyanine functionalized polyurea heterogeneous catalysts for CO2and epoxides cycloaddition 认领 引用
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作者 Yongxian Liu Zhihua Feng +7 位作者 Zhangting Dang Qingqing Hou Yue Yu Xiaofei Zhao Lingling Wang Yong He Renbo Wei Xiufu Hua 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2026年第2期157-167,共11页
Converting CO2efficiently into high-value-added chemical products represents dual value in ecological conservation and resource valorization.Designing novel catalysts integrating atom economy and process intensific... Converting CO2efficiently into high-value-added chemical products represents dual value in ecological conservation and resource valorization.Designing novel catalysts integrating atom economy and process intensificationconstitutes the cornerstone for catalytic CO2conversion.Herein,an integrated polymeric heterogeneous catalyst is constructed by covalently anchoring functional groups of quaternary ammonium(QA)and copper phthalocyanine(CuPc)onto a polyurea(PU)framework,yielding PUCuPc-QA.This catalyst is subsequently applied for CO2conversion to cyclic carbonates.Owing to the Cu2+centers in phthalocyanine and urea groups from PU acting as a Lewis acid and hydrogen bond donor(HBD)to efficientlyactivate epoxide,as well as nucleophilic attack of this activated epoxide by iodide ion(I-)dissociated from QA,PU-CuPc-QA facilitates ring-opening of epoxide.Moreover,the phthalocyanine rins and the QA cations in PU-CuPc-QA work as N-rich groups that can adsorb and active CO2.As a result,PU-CuPc-QA exhibits exceptional catalytic activity for CO2cycloaddition under mild conditions without adding any external co-catalysts.Specially,at 100℃,1.5 MPa of CO2,6%(mass)PUCuPc-QA achieve 99%propylene carbonate yield and selectivity after reacting with propylene oxide for 6 h.Combining its ability to catalyze and activate epoxide and CO2simultaneously,PU-CuPc-QA is a promising catalyst for CO2cycloaddition. 展开更多
关键词 CO2cycloaddition Copper phthalocyanine Cyclic carbonates Quaternary ammonium Hydrogen bond donor
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Construction of hierarchical ZSM-5 molecular sieves by quaternary ammonium salt-assisted acid hydrolysis of a silicon source to enhance the catalytic pyrolysis of n-pentane 认领 引用
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作者 Mengkun Luan Wenli Su +1 位作者 Huijuan Guo Yu Fan 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2026年第2期86-93,共8页
ZSM-5 molecular sieves are potential catalysts for the catalytic pyrolysis of light naphtha.Nevertheless,traditional ZSM-5 is constrained by its low yield of light olefinsand poor stability,limiting its use as a pyrol... ZSM-5 molecular sieves are potential catalysts for the catalytic pyrolysis of light naphtha.Nevertheless,traditional ZSM-5 is constrained by its low yield of light olefinsand poor stability,limiting its use as a pyrolysis catalyst.In this work,a method involving quaternary ammonium salt(QAS)-assisted acid hydrolysis of silicon sources was developed to construct hierarchical and highly crystalline ZSM-5 molecular sieves for the efficientcatalytic pyrolysis of n-pentane.The mesoporous sizes in hierarchical ZSM-5 were controlled by varying the alkyl chain length of the QASs.Diffusional measurements revealed that the diffusion time constant of n-pentane increased with increasing mesoporous size in ZSM-5.The n-pentane pyrolysis tests revealed that a suitable mesoporous size(10.8 nm)facilitated the n-pentane monomolecular cracking pathway while the hydrogen transfer reactions were inhibited.Among the series of ZSM-5 molecular sieves,the D-ZH5 catalyst synthesized by dodecyl trimethyl ammonium bromide(DTAB)-assisted acid hydrolysis of ethyl orthosilicate(TEOS)achieved the highest yields of light olefins(41.69%(mass)for ethylene and propylene)and the lowest deactivation rate(0.13%·h-1). 展开更多
关键词 Hierarchical ZSM-5 Catalytic pyrolysis Quaternary ammonium salts Acid hydrolysis Light olefins
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Rare earth-based LaCoCrZ(Z=In,Sn,Sb)equiatomic quaternary Heusler alloys:Materials for high-temperature thermoelectrics 认领 引用
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作者 M.Nandha Kumar V.Aravindan +1 位作者 N.Laihnuna M.Mahendran 《Journal of Rare Earths》 SCIE EI CAS CSCD 2026年第6期1894-1906,I0007,共13页
Rare earth-based equiatomic quaternary Heusler alloys(RE-EQHAs)LaCoCrZ(Z=In,Sn,Sb)were examined using the density functional theory(DFT)to determine their structural,mechanical,electronic,magnetic,thermodynamic,and tr... Rare earth-based equiatomic quaternary Heusler alloys(RE-EQHAs)LaCoCrZ(Z=In,Sn,Sb)were examined using the density functional theory(DFT)to determine their structural,mechanical,electronic,magnetic,thermodynamic,and transport properties.The structural and ground-state properties of these RE-EQHAs were derived using the generalized gradient approximation+modified BeckeJohnson+U(GGA+mBJ+U)technique.The mechanical stability and other physical properties were confirmed by determining their elastic constants.The calculated thermodynamic characteristics and temperatures,such as melting temperature and Debye temperature,are extremely valuable in experimental synthesis,We also calculated optical properties to anticipate the suitability of these alloys for optoelectronic applications.The electronic structu re of the RE-EQHAs under consideration indicates that they are half-metallic ferromagnetic alloys.The Boltzmann transport equations were used to compute the Seebeck coefficient,thermal conductivity,and lattice and electronic electrical conductivity.This discovery opens the way for the discovery of high-temperature thermoelectric devices by offering a comprehensive understanding of how to increase the thermoelectric figure of merit(ZT)in these materials. 展开更多
关键词 Equiatomic quaternary Heusler alloys Rare earths Electronic structure Half metal High-temperature thermoelectrics Density functional theory
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Gemini quaternary ammonium salt-enabled efficient interface and bulk engineering for inverted perovskite solar cells 认领 引用
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作者 Yingqi Zuo Gang Wang +9 位作者 Yuanwei Pu Zhen He Mengjun Teng Yongchao Liang Qiaofei Hu Qiyu Yang Haijun Tan Jiang Wang Jian Zhang Jian Xiong 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2026年第7期245-258,I0008,共14页
Perovskite/electron transport layer(ETL)interface as well as defects in perovskite films greatly limit the efficiency and stability of inverted perovskite solar cells(PSCs).Although traditional ammonium salts are wide... Perovskite/electron transport layer(ETL)interface as well as defects in perovskite films greatly limit the efficiency and stability of inverted perovskite solar cells(PSCs).Although traditional ammonium salts are widely used for surface passivation,their single adsorption sites and restricted spatial configurations hinder the development of more effective passivators and interface modifiers.To address these challenges,we first propose an efficient interface and bulk engineering strategy based on a Gemini quaternary ammonium salt,1,2-bis(hexyldimethylammonium)ethane dibromide(HMAEB),which targets both the aforementioned interface issues and perovskite bulk defects.The HMAEB molecule features bisquaternary ammonium cations(–N+(CH3)2–)as dual-site anchoring groups and an ethane bridge(–CH2–CH2–)as a flexible linker—designs that enable adaptive and firm binding to the perovskite surface.Meanwhile,its two hydrophobic hexyl chains drive ordered vertical adsorption at the perovskite/ETL interface,further optimizing the interface contact.Ultimately,HMAEB not only constructs efficient charge-transport channels at the perovskite/ETL interface but also realizes bulk reconstruction,defect passivation,stress relief,and a more hydrophobic perovskite surface,collectively boosting device performance and stability.As a result,the HMAEB-modified device achieves a power conversion efficiency of25.56%,with the unencapsulated device retaining over 90%of its initial efficiency after 4320 h in N2,240 h in relative humidity(RH)of 45–55%in air,as well as 768 h at 65℃. 展开更多
关键词 Gemini quaternary ammonium salt Interface and bulk engineering Inverted perovskite solar cells
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COAP-Pd Catalyzed Asymmetric Ring-Opening Allylic Alkylation for Linear Unsaturated Quaternary Amino Acid Derivatives 认领 引用
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作者 Yan-Qi Ma Min Chen +3 位作者 Chuan Wang Huang-Jie Zhou Jia-Li Zhang Xing-Wang Wang 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2026年第11期1835-1843,共9页
Unsaturated quaternary amino acids are essential building blocks for the construction of non‑natural peptides and proteins.Herein,ring‑opening allylic alkylation between vinyl(hetero)cyclopropanes and 4‑substituted az... Unsaturated quaternary amino acids are essential building blocks for the construction of non‑natural peptides and proteins.Herein,ring‑opening allylic alkylation between vinyl(hetero)cyclopropanes and 4‑substituted azlactones was developed,which was catalyzed by our designed COAP‑Pd complexes.Several series ofγ,δ‑unsaturated quaternary amino acid derivatives were obtained in good yields with high regio‑and enantioselectivity.The transformations exhibited good tolerance toward a variety of azlactone substrates,enabling the efficient synthesis of a diverse library of chiralγ,δ‑unsaturated quaternary amino acid derivatives with functional allylic side chains.The synthetic utility of this protocol was validated through gram‑scale reactions and subsequent functional group transformations,including hydrolysis under acidic condition to afford non‑natural quaternary amino acids,alcoholysis under basic conditions to give quaternary amino acid esters,as well as epoxidation of the pendent alkenyl groups.In addition,the chiral 4,5‑dihydrooxazole scaffolds with potential pharmaceutical value were also constructed via further cyclization of the corresponding quaternary amino alcohol derivatives,which were prepared from reductive ring‑opening of the corresponding azlactone moieties in the presence of reducing reagents.Moreover,the coordination models and the active catalytic species were further deduced by X‑ray crystallographic analysis and(31)^P NMR experiments.Notably,the resultingγ,δ‑unsaturated quaternary amino acid derivatives featured unique linear side chains and quaternary carbon centers.And that,the linear allylic side chains held the promise as a linkage for modifying drugs and natural products,as it allowed for the conjugation of two bioactive scaffolds. 展开更多
关键词 Asymmetric catalysis Ring‑opening allylic alkylation Non‑natural amino acid Functional allylic side chains Enantioselectivity γ,δ‑Unsaturated quaternary amino acid COAP‑Pd catalysis Chirality
Enhanced electrocatalytic oxidation of high-salinity quaternary ammonium compound wastewater using CNTs-(RuxIryO2)/Ti Anode 认领 引用
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作者 Hao-Tian Liu Han-Qing Zhao +7 位作者 Yi-Rui Yang Shuang Wu Jia-Ping Huang Rui-Han Yu Hongcheng Bai Aqiang Ding Daijun Zhang Peili Lu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2025年第11期879-889,共11页
The organic pollutants,such as quaternary ammonium compounds,in high salinity flowback water from shale gas extraction may pose a severe risk to public health.Conventional biological technologies have limited effectiv... The organic pollutants,such as quaternary ammonium compounds,in high salinity flowback water from shale gas extraction may pose a severe risk to public health.Conventional biological technologies have limited effectiveness in the treatment of high-salt wastewaters,whereas electrocatalytic oxidation has shown potential for treating organic pollutants in high-salt flowback water.This study developed a carbon nanotubes(CNTs)doped Ru/Ir oxide coated Ti electrode CNTs-(RuxIryO2)/Ti,which exhibited enhanced electrocatalytic performance for the treatment of quaternary ammonium compound in high-salt wastewater compared to the control metal oxide coated Ti anode(RuxIryO2)/Ti,with pseudofirst-order reaction rate constant improved from 7.36×10-3 to 1.12×10-2 min−1.Moreover,the CNTs-(RuxIryO2)/Ti anode electrocatalytic oxidation system exhibited excellent cycling stability.Mechanism studies indicated that the CNTs-(RuxIryO2)/Ti electrode enhanced singlet oxygen(1O2)generation,which played a major role in pollutant degradation.Furthermore,the formation of high concentrations of HClO and H2O2 further facilitated the generation of 1O2.This study may provide an efficient and green technology for the treatment of organic pollutants in high-salt shale gas flowback water. 展开更多
关键词 High salt wastewater Quaternary ammonium compound Electrocatalytic oxidation CNTs doping Dimensionally stable anode
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Late Quaternary slip rate of the Northern Margin Fault of the Huaizhuo Basin in the North China Block and its seismological implications 认领 引用
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作者 Li Lu-wei Yu Zhong-yuan +4 位作者 Qiu Chun-miao Wang Wen-xuan Zhao Qian Zheng Rong-ying Yang Yan-Lin 《Applied Geophysics》 SCIE CSCD 2025年第1期53-70,232,233,共18页
Although the late Quaternary slip rate of the Northern Margin Fault of the Huaizhuo Basin(NFHB)was studied approximately 30 years ago using thermoluminescence and geomorphic methods,the underlying uncertainty cannot b... Although the late Quaternary slip rate of the Northern Margin Fault of the Huaizhuo Basin(NFHB)was studied approximately 30 years ago using thermoluminescence and geomorphic methods,the underlying uncertainty cannot be neglected,considering the limitations resulting from age and displacement measurements.Accordingly,we attempted to re-estimate the late Quaternary slip rate of the NFHB using high-precision remote sensing image interpretation,large-scale geological and geomorphic mapping,paleoseismic analysis,and Quaternary geochronology testing.The results,based on stratigraphic dislocation and age constraint in the trenches,show that the present deformation of the NFHB has been dominated by the extension,with a vertical slip rate~0.04-0.11 mm/a.We estimate a vertical slip rate of~0.06 mm/a,with an R2 value of~0.91,which is much lower than the~0.5 mm/a result estimated previously.There are three possible reasons for this discrepancy.The first is the limitation resulting from dating and displacement measurements in earlier studies;the second is the slip decomposition caused by multiple branches of the NFHB,which leads to the low slip rate observed at a single fault;and third possible explanation is that the fault may be locked at present with a low slip rate,which means that the earthquake hazard of the NFHB cannot be ignored,and more in-depth research,such as geodetic and intensive observations of earthquake precursors,is urgently needed.This discovery poses a new challenge for the active study of the NFHB and the northeast corner of the Ordos Plateau in the North China Block. 展开更多
关键词 North China Block The Northern Margin Fault of the Huaizhuo Basin Late Quaternary slip rate Seismological Implications
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Preparation and Corrosion Resistance Mechanism of Magnesium-Lithium Alloy Micro-arc Oxidation/Quaternary LDHs@GO Self-healing Composite Film 认领 引用
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作者 Zhenzhen Tian Rongqian Wu +7 位作者 Fubing Yu Yan Zhou Wenhui Yao Yuan Yuan Zhihui Xie Yanlong Ma Atrens Andrej Liang Wu 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2025年第9期1545-1558,共14页
Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports t... Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports the successful hydrothermal preparation of a MgLiAlCe-LDHs@GO flm on a MAO-coated Mg–Li alloy following Ce confnement.The graphene oxide(GO)sheet increased the difusion path of the corrosive media,and the addition of rare-earth cerium ions(Ce3+)endowed the flm with a certain self-healing ability,which signifcantly improved the corrosion resistance of the flm,and the corrosion current density(icorr)reached 3.27×10−8A cm−2.The synergistic action of GO and Ce3+can achieve long-term corrosion protection for the substrate.The corrosion resistance mechanism of MgLiAlCe-LDHs@GO flm was discussed by the scanning vibration electrode technique(SVET). 展开更多
关键词 Micro-arc oxidation(MAO) Magnesium-lithium alloy Quaternary layer doubled hydroxides(LDHs) Graphene oxide Corrosion mechanism
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Efficient fixation of CO2 to cyclic carbonates and oxazolidinones with multi-hydroxyl bis-(quaternary ammonium) ionic liquids as catalysts under mild conditions 认领 引用
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作者 BAI Yumeng YANG Haijian 《中南民族大学学报（自然科学版）》 CAS 2025年第1期1-8,共8页
A series of multi-hydroxyl bis-(quaternary ammonium)ionic liquids(Ils1‒7)was prepared as bifunctional catalysts for the chemical fixation of CO2.All these ionic liquid compounds were efficient for the catalytic syn... A series of multi-hydroxyl bis-(quaternary ammonium)ionic liquids(Ils1‒7)was prepared as bifunctional catalysts for the chemical fixation of CO2.All these ionic liquid compounds were efficient for the catalytic synthesis of cyclic carbonates and oxazolidinones via the cycloaddition reactions between CO2 and epoxides or aziridines with excellent yield and high selectivity in the absence of co-catalyst,metal and solvent.Due to the synergistic effects of hydroxyl groups and halogen anion,the cycloaddition reactions proceeded smoothly either at atmospheric pressure or room temperature.The selectivity for substituted oxazolidinones at 5-and 4-positions can be tuned via changing the reaction conditions.Finally,possible mechanisms including the activation of both CO2 and epoxide or aziridines were proposed based on the literatures and experimental results. 展开更多
关键词 chemical conversion of CO2 multi-hydroxyl bis-(quaternary ammonium) ionic liquids
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Synthesis of isosorbide-based polycarbonates via melt polycondensation catalyzed by quaternary ammonium ionic liquids 认领 引用 被引量：14
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作者 Wei Sun Fei Xu +3 位作者 Weiguo Cheng Jian Sun Guoqing Ning Suojiang Zhang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2017年第5期908-917,共10页
A series of quaternary ammonium ionic liquids(ILs)were synthesized and employed as catalysts for the production of poly(isosorbide carbonate)(PIC)from diphenyl carbonate and isosorbide via a melt polycondensation proc... A series of quaternary ammonium ionic liquids(ILs)were synthesized and employed as catalysts for the production of poly(isosorbide carbonate)(PIC)from diphenyl carbonate and isosorbide via a melt polycondensation process.The relationship between the anions of the ILs and the catalytic activities was investigated,and the readily‐prepared IL tetraethylammonium imidazolate(TEAI)was found to exhibit the highest catalytic activity.After optimizing the reaction conditions,a PIC with a weight‐average molecular weight(Mw)of25600g/mol was obtained,in conjunction with an isosorbide conversion of92%.As a means of modifying the molecular flexibility and thermal properties of the PIC,poly(aliphatic diol‐co‐isosorbide carbonate)s(PAIC)s were successfully synthesized,again using TEAI,and polymers with Mw values ranging from29000to112000g/mol were obtained.13C NMR analyses determined that the PAIC specimens had random microstructures,while differential scanning calorimetry demonstrated that each of the PAICs were amorphous and had glass transition temperatures ranging from50to115°C.Thermogravimetric analyses found Td‐5%values ranging from316to332°C for these polymers.Based on these data,it is evident that the incorporation of linear or cyclohexane‐based diol repeating units changed the thermal properties of the PIC. 展开更多
关键词 Quaternary ammonium ionic liquid catalyst Isosorbide Polycarbonate Melt polycondensation Aliphatic diol
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Effects of quaternary ammonium chain length on the antibacterial and remineralizing effects of a calcium phosphate nanocomposite 认领 引用 被引量：17
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作者 Ke Zhang Lei Cheng +2 位作者 Michael D Weir Yu-Xing Bai Hockin HK Xu 《International Journal of Oral Science》 SCIE CAS CSCD 2016年第1期45-53,共9页
Composites containing nanoparticles of amorphous calcium phosphate （NACP） remineralize tooth lesions and inhibit caries. A recent study synthesized quaternary ammonium methacrylates （QAMs） with chain lengths （CLs... Composites containing nanoparticles of amorphous calcium phosphate （NACP） remineralize tooth lesions and inhibit caries. A recent study synthesized quaternary ammonium methacrylates （QAMs） with chain lengths （CLs） of 3-18 and determined their effects on a bonding agent. This study aimed to incorporate these QAMs into NACP nanocomposites for the first time to simultaneously endow the material with antibacterial and remineralizing capabilities and to investigate the effects of the CL on the mechanical and biofilm properties. Five QAMs were synthesized： DMAPM （CL3）, DMAHM （CL6）, DMADDM （CL12）, DMAHDM （CL16）, and DMAODM （CL18）. Each QAM was incorporated into a composite containing 20% NACP and 50% glass fillers. A dental plaque microcosm biofilm model was used to evaluate the antibacterial activity. The flexural strength and elastic modulus of nanocomposites with QAMs matched those of a commercial control composite （n = 6; P 〉 0.1）. Increasing the CL from 3 to 16 greatly enhanced the antibacterial activity of the NACP nanocomposite （P 〈 0.05）; further increasing the CL to 18 decreased the antibacterial potency. The NACP nanocomposite with a CL of 16 exhibited biofilm metabolic activity and acid production that were 10-fold lesser than those of the control composite. The NACP nanocomposite with a CL of 16 produced 2-log decreases in the colony-forming units （CFU） of total microorganisms, total streptococci, and mutans streptococci. In conclusion, QAMs with CLs of 3-18 were synthesized and incorporated into an NACP nanocomposite for the first time to simultaneously endow the material with antibacterial and remineralization capabilities. Increasing the Ceduced the metabolic activity and acid production of biofilms and caused a 2-log decrease in CFU without compromising the mechanical properties. Nanocomposites exhibiting strong anti-biofilm activity, remineralization effects, and mechanical properties are promising materials for tooth restorations that inhibit caries. 展开更多
关键词 antibacterial nanocomposite calcium phosphate nanoparticles caries inhibition human saliva microcosm biofilm quaternary ammonium chain length
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Synthesis of cyclic carbonates from epoxides or olefins and CO_2 catalyzed by metal-organic frameworks and quaternary ammonium salts 认领 引用 被引量：10
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作者 Olga V. Zalomaeva Nataliya V. Maksimchuk +3 位作者 Andrey M. Chibiryaev Konstantin A. Kovalenko Vladimir P. Fedin Bair S. Balzhinimaev 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2013年第1期130-135,共6页
Catalytic properties of the metal-organic framework Cr-MIL-101 in solvent-free cycloaddition of CO2 to epoxides to produce cyclic carbon- ates using tetrabutylammonium bromide as co-catalyst have been explored under m... Catalytic properties of the metal-organic framework Cr-MIL-101 in solvent-free cycloaddition of CO2 to epoxides to produce cyclic carbon- ates using tetrabutylammonium bromide as co-catalyst have been explored under mild reaction conditions （8 bar CO2, 25 ~C）. Styrene and propylene carbonates were formed with high yields （95% and 82%, respectively）. Catalytic performance of Cr-MIL-101 was compared with other MOFs： Fe-MIL-101, Zn-MOF-5 and HKUST-1, The catalytic properties of different quaternary ammonium bromides, Cr-MIL-101 as well as PW12/Cr-MIL-101 composite material have been assessed in oxidative carboxylation of styrene in the presence of both tert-butyl hydroperoxide and H202 as oxidants at 8-100bar CO2 and 25-80 ~C with selectivity to styrene carbonate up to 44% at 57% substrate conversion. 展开更多
关键词 carbon dioxide cyclic carbonates cycloaddition heterogeneous catalysis metal-organic framework oxidative carboxylation quaternary am-monium salts
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Paleoenvironmental changes during the late Quaternary as inferred from foraminifera assemblages in the Laizhou Bay 认领 引用 被引量：10
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作者 YAO Jing YU Hongjun +3 位作者 XU Xingyong YI Liang CHEN Guangquan SU Qiao 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2014年第10期10-18,共9页
Controlled by climate changes, there were three large-scale transgressions and regressions around the Bohai Sea during the late Quaternary, which were accepted by most geologists. However, a big controversy still exis... Controlled by climate changes, there were three large-scale transgressions and regressions around the Bohai Sea during the late Quaternary, which were accepted by most geologists. However, a big controversy still exists about the time when the transgressions occurred separately. In order to find out the process of the paleoenvironmental changes around the Bohai Sea in the late Quaternary, the foraminifera assemblages from a new borehole Lz908 in the southern coast of the Laizhou Bay were studied, and then the transgressive strata were indentified. Combined with accelerator mass spectrometry radiocarbon 14C（AMS14C） and optically stimulated luminescence（OSL） ages, the occurrence time of these transgressions were re-determined. The result showed that three major large-scale transgressions occurred separately at the beginning of marine isotopic stage 7（MIS7）, the last interglacial period（MIS5） and the Holocene. In addition, a small-scale transgression occurred in the mid-MIS6, and the corresponding transgressive stratum was deposited. The transgressive deposition of MIS3 was also discovered in this study. However, the characteristics of the foraminifera indicated the environment during this period was colder than that in the MIS5. By comparison with the global sea-level changes, the paleoenvironmental changes around the Bohai Sea in the late Quaternary can be consistent with the global climate changes. 展开更多
关键词 foraminifera assemblage late Quaternary environmental changes Laizhou Bay Bohai Sea
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Preparation of cross-linked magnetic chitosan with quaternary ammonium and its application for Cr(Ⅵ) and P(Ⅴ) removal 认领 引用 被引量：11
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作者 Wei Yao Pinhua Rao +2 位作者 Irene M.C.Lo Wenqi Zhang Wenrui Zheng 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2014年第12期2379-2386,共8页
Pollutants that exist in anionic species are issues of concern in water treatment. Compared to cationic pollutants, the removal of anionic pollutants by adsorption is more difficult because most adsorbents carry predo... Pollutants that exist in anionic species are issues of concern in water treatment. Compared to cationic pollutants, the removal of anionic pollutants by adsorption is more difficult because most adsorbents carry predominantly negative charges in neutral and alkaline environments. In this study, a cross-linked chitosan derivative with quaternary ammonium and magnetic properties（QM-chitosan） was prepared and employed to remove chromium（VI） and phosphorus（V）（Cr（VI） and P（V）） from aqueous environments. The QM-chitosan was characterized by Fourier transform infrared spectrometry（FT-IR）,thermogravimetric analysis（TGA）, energy dispersive X-ray（SEM-EDX） and zeta potential.Batch experiments show that QM-chitosan can effectively remove Cr（VI） and P（V）, and the main mechanism was believed to be electrostatic interaction. A pseudosecond-order model was fitted to describe the kinetic processes of Cr（VI） and P（V） removal. The adsorption isotherms of both Cr（VI） and P（V） on the QM-chitosan were well fitted by the Langmuir isotherm equation. The saturated adsorption capacity of P（V）（2.783 mmol/g） was found to be higher than that of Cr（VI）（2.323 mmol/g）, resulting from the size of the H2PO-4ions being smaller than that of the HCr O-4ions. However, the theoretical calculation and experimental results showed that QM-chitosan had a stronger affinity for Cr（VI） than P（V）. The adsorption–desorption of the QM-chitosan was evaluated, and high regeneration rates were demonstrated. 展开更多
关键词 Magnetic chitosan Quaternary ammonium Cr（VI） P（V） Adsorption
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Quaternary Lake Deposits of Nam Co, Tibet, with a Discussion of the Connection of Nam Co with Ring Co-Jiuru Co 认领 引用 被引量：9
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作者 朱大岗 赵希涛 +6 位作者 孟宪刚 吴中海 吴珍汉 冯向阳 邵兆刚 刘琦胜 杨美玲 《Acta Geologica Sinica(English Edition)》 SCIE CAS 2002年第3期283-291,共9页
Shorelines are widespread and lake deposits and lake geomorphology are welldeveloped on the northern Tibetan Plateau. Through field observations of lacustrine deposits of NamCo-the highest and largest Quaternary lake ... Shorelines are widespread and lake deposits and lake geomorphology are welldeveloped on the northern Tibetan Plateau. Through field observations of lacustrine deposits of NamCo-the highest and largest Quaternary lake in Tibet, the authors found four-step shore terracescomposed of sands and clays with well-developed horizontal bedding and 3-12 m, 15-22 m, 25-30 m and35-45 m higher than the lake surface respectively, lacustrine deposits resting on the bedrocks and60-150 m higher than the lake surface, and up to approx 50 levees composed of oblate lakeshoregravels. Moreover they found lacustrine and lakeshore deposits making up the terraces and levees onthe bottoms of wide dividing valleys connecting Nam Co with the Rencoyuema, Rencogongma and Jiuru Conorthwest of Nam Co (the valley bottoms are 20 m, 90 m and 60 m higher than the above-mentionedthree lakes) and on slopes north of it, i.e. terraces II and III of Nam Co. Thus they confirm thatNam Co and Ring Co-Jiuru Co had connected with each other several times, i.e. formed a unified largelake several times, rather than had been different lakes connected only by river channels. Fromindications such as the distribution of the highest shoreline and lake deposits and geomorphology,the authors conclude that the total area of the old large lakes on the northern Tibetan Plateau is afew times larger than that of the modern lakes and that the last-stage old large lakes formed inthe interglacial interval of the last glaciation. 展开更多
关键词 Tibet Nam Co Quaternary lake deposits old large lake
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Fundamentals and photocatalytic hydrogen evolution applications of quaternary chalcogenide semiconductor:Cu2ZnSnS4 认领 引用 被引量：10
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作者 Xin-Long Zheng Ying-Jie Yang +9 位作者 Yu-Hao Liu Pei-Lin Deng Jing Li Wei-Feng Liu Peng Rao Chun-Man Jia Wei Huang Yan-Lian Du Yi-Jun Shen Xin-Long Tian 《Rare Metals》 SCIE EI CAS CSCD 2022年第7期2153-2168,共16页
Inexpensive,safe,and efficient conversion of solar energy to hydrogen from water splitting requires the development of effective and durable photocatalysts.Cu2ZnSnS4(CZTS),the emerging quaternary chalcogenide ma... Inexpensive,safe,and efficient conversion of solar energy to hydrogen from water splitting requires the development of effective and durable photocatalysts.Cu2ZnSnS4(CZTS),the emerging quaternary chalcogenide material for solar energy conversion,possesses many advantages,such as narrow direct band gap(1.5 eV),nontoxic,earth-abundance,and low melting point.Currently,CZTS-based photocatalysts have been extensively investigated for their application as an active photocatalyst in hydrogen evolution from water splitting,while the performance is still highly needed to be improved for the practical applications.In this review,first,the crystal and band structure properties of CZTS are briefly introduced,and afterward,the basic principle of photocatalytic hydrogen evolution from water splitting is discussed.Subsequently,the performance and status of bare CZTS,the combination of CZTS and co-catalysts,and CZTSbased heterojunction photocatalysts for hydrogen evolution are reviewed and discussed in detail.Finally,the issues and challenges currently encountered in the application of CZTS and their possible solutions for developing advanced CZTS photocatalysts are provided. 展开更多
关键词 Cu2ZnSnS4 Quaternary chalcogenide Photocatalyst Hydrogen evolution
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Revisiting Late Quaternary Slip-rate along the Maqu Segment of the Eastern Kunlun Fault,Northeast Xizang 认领 引用 被引量：7
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作者 LI Jian ZHANG Yueqiao +3 位作者 LI Hailong XIONG Jinhong LI Jianhua WU Tairan 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第2期486-502,共17页
The Late Quaternary slip rate along the Maqu segment of the eastern Kunlun Fault was estimated using a combination of high-resolution remote sensing imagery interpretation,field observations and differential Global Po... The Late Quaternary slip rate along the Maqu segment of the eastern Kunlun Fault was estimated using a combination of high-resolution remote sensing imagery interpretation,field observations and differential Global Positioning System(GPS)measurements of offset river terraces,and 14 C dating of snail shells collected from offset risers.The results show that the left-slip rate along the segment is 3–5 mm/a,and that the vertical slip rate is 0.3–0.5 mm/a.Both the horizontal and vertical slips on the segment remain consistent over a distance of~100 km.It means that no slip gradient as previously suggested occurred along the Maqu segment,and which thus might behave as an independent seismogenic fault.Judging from multiple relationships among young terrace offsets,we infer that co-seismic surface rupture produced by a characteristic earthquake with a magnitude of Ms7.0–7.5 on the Maqu fault could generate a horizontal slip of 4.5–5 m and a vertical slip of 0.45–0.5 m,with a corresponding ratio(Dh/Dv)of about 9.Two surface rupture events must have occurred over the past 3300 years,the latest one possibly between 1485 cal BP and 1730 cal BP. 展开更多
关键词 eastern Kunlun fault Maqu fault Late Quaternary slip-rate offset terraces paleo-seismicity
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Geochemistry and petrogenesis of Quaternary volcanism from the islets in the eastern Beibu Gulf: evidence for Hainan plume 认领 引用 被引量：13
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作者 LI Naisheng YAN Quanshu +1 位作者 CHEN Zhihua SHI Xuefa 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2013年第12期40-49,共10页
Some of the islets in the eastern Beibu Gulf are covered by Quaternary volcano strata. The rock samples from these islets mainly consist of quartz tholeiites （at Shenjiandao）, olivine tholeiites （at Linshidao and X... Some of the islets in the eastern Beibu Gulf are covered by Quaternary volcano strata. The rock samples from these islets mainly consist of quartz tholeiites （at Shenjiandao）, olivine tholeiites （at Linshidao and Xieyang- dao） and alkali basalts （at Yangpubi and Jianshidao）, and basically represent four periods of the Quaternary volcanism of Hainan Island and its adjacent regions. Except for the samples from Shenjiandao, most of the Quaternary volcanics of these islets belong to alkali magma series. The trace element characteristics of all of these samples show they are OIB （oceanic island basalt） -like, which implies that their deep geodynamic setting may be related to a mantle plume. The Sr-Nd-Pb isotopic compositions show that the mantle source beneath the Quaternary strata can be regarded as a result of binary mixing between a depleted, DMM （de- pleted MORB mantle）-like source and an enriched mantle type 2 （EM2）. The EM2 may be originated from the Hainan mantle plume, and has been metasomatized by carbonaceous fluids released from ancient re- cycled oceanic crust at an asthenospheric mantle level. These features, together with typical trace element ratios, reflect that the parent magma was not subjected to crustal contamination during its ascent to the surface. This study provides further petrological and geochemical evidence for the existence of the Hainan mantle plume. 展开更多
关键词 enriched mantle type 2 （EM2） mantle source Quaternary volcanism Hainan mantle plume,eastern Beibu Gulf
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