Emulsifier-free poly（methyl methacrylate-styrene） [P（MMA-St）] nanospheres with an average particle size of 100 nm were synthesized in an isopropyl alcoholwater medium by a solvothermal method. Then, through radica...Emulsifier-free poly（methyl methacrylate-styrene） [P（MMA-St）] nanospheres with an average particle size of 100 nm were synthesized in an isopropyl alcoholwater medium by a solvothermal method. Then, through radical graft copolymerization of thermo-sensitive mono- mer N-isopropylacrylamide （NIPAm） and hydrophilic monomer acrylic acid （AA） onto the surface of P（MMA- St） nanospheres at 80 ℃, a series of thermo-sensitive polymer nanospheres, named SD-SEAL with different lower critical solution temperatures （LCST）, were prepared by adjusting the mole ratio of NIPAm to AA. The products were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, particle size distribution, and specific surface area analysis. The temperature-sensitive behavior was studied by light transmittance tests, while the sealing performance was investigated by pressure transmission tests with Lungmachi Formation shales. The experimental results showed that the synthesized nanoparticles are sensitive to temperature and had apparent LCST values which increased with an increase in hydrophilic monomer AA. When the temperature was higher than its LCST value, SD- SEAL played a dual role of physical plugging and chemical inhibition, slowed down pressure transmission, and reduced shale permeability remarkably. The plugged layer of shale was changed to being hydrophobic, which greatly improved the shale stability展开更多
The fabrication of S-scheme heterojunctions with fast charge transfer and good interface contacts,such as intermolecularπ–πinteractions,is a promising approach to improve photocatalytic performance.A unique two-dim...The fabrication of S-scheme heterojunctions with fast charge transfer and good interface contacts,such as intermolecularπ–πinteractions,is a promising approach to improve photocatalytic performance.A unique two-dimensional/two-dimensional(2D/2D)S-scheme heterojunction containing TpPa-1-COF/g-C_(3)N_(4) nanosheets(denoted as TPCNNS)was developed.The established maximum interfacial interaction between TpPa-1-COF NS and g-C_(3)N_(4) NS may result in aπ–πconjugated heterointerface.Furthermore,the difference in the work functions of TpPa-1-COF and g-C_(3)N_(4) results in a large Fermi level gap,leading to upward/downward band edge bending.The spontaneous interfacial charge transfer from g-C_(3)N_(4) to TpPa-1-COF at theπ–πconjugated interface area results in the presence of a built-in electric field,according to the charge density difference analysis based on density functional theory calculations.Such an enhanced built-in electric field can efficiently drive directional charge migration via the S-scheme mechanism,which enhances charge separation and utilization.Thus,an approximately 2.8 and 5.6 times increase in the photocatalytic hydrogen evolution rate was recorded in TPCNNS-2(1153μmol g^(-1) h^(-1))compared to pristine TpPa-1-COF and g-C_(3)N_(4) NS,respectively,under visible light irradiation.Overall,this work opens new avenues in the fabrication of 2D/2Dπ–πconjugated S-scheme heterojunction photocatalysts with highly efficient hydrogen evolution performance.展开更多
The complex [Cu2（H2dhbd）2（tpy）2]·CH3OH·4H2O 1 （H4dhbd =2,3-dihydroxybutanedioic acid, tpy = 2,2＇：6＇,2＇＇-terpyridine） has been hydrothermally synthesized and characterized by single-crystal X-ray d...The complex [Cu2（H2dhbd）2（tpy）2]·CH3OH·4H2O 1 （H4dhbd =2,3-dihydroxybutanedioic acid, tpy = 2,2＇：6＇,2＇＇-terpyridine） has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis. The crystal is of triclinic, space groups Pi with a= 8.6859（17）, b = 11.223（2）, c = 12.275（2）A, α = 112.454（3）, β= 98.435（3）, γ = 105.593（3）°, V= 1022.5（3） A^3, Z = 1, C38H42Cu2N6O18, Mr = 997.86, Dc = 1.621 g/cm^3, μ= 1.127 mm^-1, F（000） = 514, T = 293（2） K, the final R = 0.0539 and wR = 0.1394 for 3550 observed reflections with I 〉 2σ（I）. In the dinuclear unit, two Cun atoms are bridged by two H2dhbd chelate anions, forming a 14-membered ring, in which the distance of Cu…Cu atoms is 7.0526（12）A. Adjacent dinuclear units are constituted through π-π interactions and C-H…O hydrogen-bonding interactions, fashioning the final 3-D supramolecular framework with 1-D open channels. Variable-temperature magnetic susceptibility measurement indicates the presence of weak antiferromagnetic exchange interactions between Cu^II ions.展开更多
Two 3D 4-fold interpenetrated metal-organic frameworks, [Mn（L）（bpy）]n （1） and [Cu（HL）（bpy）]n （2）（H3L = 4,4＇,4＇＇-（benzene-1,3,5-triyl-tri（methyleneoxy）） tribenzoic acid, bpy = 4,4′-bipyridine）, we...Two 3D 4-fold interpenetrated metal-organic frameworks, [Mn（L）（bpy）]n （1） and [Cu（HL）（bpy）]n （2）（H3L = 4,4＇,4＇＇-（benzene-1,3,5-triyl-tri（methyleneoxy）） tribenzoic acid, bpy = 4,4′-bipyridine）, were synthesized under hydrothermal conditions, and characterized by element analyses, IR spectra, thermogravimetric analyses, X-ray powder diffraction and magnetic property studies. The single-crystal X-ray analyses revealed that 1 and 2 are homogeneous. 1 crystallizes in monoclinic, space group Cc with a = 26.794（2）, b = 11.6346（10）, c = 21.4614（18） ？, β = 91.570（2）°, V = 6687.9（10） A^3, Z = 8, Mr = 736.59, D = 1.463 g·cm^（-3）, μ = 0.458 mm^-1c, R（int） = 0.0524, F（000） = 3040, the final R = 0.0844 and wR = 0.2266 for 8092 observed reflections（I 〉 2σ（I））. 2 crystallizes in monoclinic, space group Cc with a = 27.609（12）, b = 11.126（10）, c = 21.490（9） ？, β = 92.131（2）°, V = 6597（5） A^3, Z = 8, Mr = 746.21, Dc = 1503 g·cm^（-3）, μ = 0.726 mm^-1, R（int） = 0.0542, F（000） = 3080, the final R =0.0681 and wR = 0.1831 for 6777 observed reflections（I 〉 2σ（I））. Two compounds are 3D [2＋2]-type 4-fold interpenetrated frameworks with（6^3）（6^9.8） hms topology. The magnetic study of compound 2 shows the presence of weak antiferromagnetic interaction between the Cu^Ⅱ ions in 2.展开更多
Healthcare security and privacy breaches are occurring in the United States (US), and increased substantially during the pandemic. This paper reviews the National Institute of Standards and Technology (NIST) publicati...Healthcare security and privacy breaches are occurring in the United States (US), and increased substantially during the pandemic. This paper reviews the National Institute of Standards and Technology (NIST) publication base as an effective solution. The NIST Special Publication 800-66 Revision 1 was an essential standard in US healthcare, which was withdrawn in February 2024 and superseded by SP 800-66 Revision 2. This review investigates the academic papers concerning the application of the NIST SP 800-66 Revision 1 standard in the US healthcare literature. A systematic review method was used in this study to determine current knowledge gaps of the SP 800-66 Revision 1. Some limitations were employed in the search to enforce validity. A total of eleven articles were found eligible for the study. Consequently, this study suggests the necessity for additional academic papers pertaining to SP 800-66 Revision 2 in the US healthcare literature. In turn, it will enhance awareness of safeguarding electronic protected health information (ePHI), help to mitigate potential future risks, and eventually reduce breaches.展开更多
The new ligand 2-（（pyridin-4-ylmethyl）thio）-5-（quinoline-2-yl）-1,3,4-oxadiazole（L） and Ag Cl O4 produced a new coordination polymer： [（Ag2L2Cl O4）ClO 4]n（1）. The complex has been characterized by single-c...The new ligand 2-（（pyridin-4-ylmethyl）thio）-5-（quinoline-2-yl）-1,3,4-oxadiazole（L） and Ag Cl O4 produced a new coordination polymer： [（Ag2L2Cl O4）ClO 4]n（1）. The complex has been characterized by single-crystal X-ray diffraction, IR, TGA, PXRD, UV and elemental analysis. Compound 1 crystallizes in triclinic system, space group P1, with a = 8.4593（5）, b = 14.5903（9）, c = 15.7908（10） A, α = 97.357（5）, β = 99.116（5）, γ = 104.470（5）°, V = 1834.43（20） A3, Dc = 1.91056 g/cm^3, Mr = 1055.38, Z = 2, F（000） = 1048, u = 1.399 mm-1, the final S = 1.002, R = 0.049 and wR = 0.105. The compound consists of a double helix chain. The neighboring chains interact via two kinds of π-π interactions to form a two-dimensional（2D） sheet. Each sheet interacts with the neighboring sheets via π-π interactions to form an extended 3D supramolecular network.展开更多
Damage reasons of purging plugs for refining ladle and research progress on thermal shock resistance of corundum- spinel purging plugs were summarized. Research achievements and application results of nonoxides bonded...Damage reasons of purging plugs for refining ladle and research progress on thermal shock resistance of corundum- spinel purging plugs were summarized. Research achievements and application results of nonoxides bonded corundum purging plugs for refining ladle were briefly reviewed. The further research and developing trend of purging plugs was proposed.展开更多
The aluminophosphate molecular sieve VPI-5 has received much attention as a new structure containing one-dimensional circular pores circumscribed by 18 tetrahedral atoms. The AlPO;-8 is another new type of structure w...The aluminophosphate molecular sieve VPI-5 has received much attention as a new structure containing one-dimensional circular pores circumscribed by 18 tetrahedral atoms. The AlPO;-8 is another new type of structure which was found to contain 1 4-ring open pores. Recently, we have successfully synthesized the molecular sieves of VPI-5 and AlPO;-8, and found that the mixture of VPI-5 and AlPO;-8 was easily formed under similar conditions, and VPI-5 can be converted to AlPO;-8 by dehydration via heating. It is suggested that there exists relationship between the structures of VPI-5 and A1PO;-8. Therefore, the study on the transition and relationship between VPI-5 and A1PO;-8 is very important for designing and preparing new molecular sieves with new structures.展开更多
井眼轨道控制系统包括轨道设计、丛式井防碰以及测斜数据分析处理等多个功能模块,需要满足不同井型设计、施工与数据分析的需求,同时要考虑系统可维护性、可扩展性,以满足现场应用的新需求。采用传统设计方法会面临模块化不足、维护升...井眼轨道控制系统包括轨道设计、丛式井防碰以及测斜数据分析处理等多个功能模块,需要满足不同井型设计、施工与数据分析的需求,同时要考虑系统可维护性、可扩展性,以满足现场应用的新需求。采用传统设计方法会面临模块化不足、维护升级困难的窘境,因此提出一种基于可扩展框架的井眼轨道控制系统软件。该软件参考开放服务网关协议(Open Service Gateway initiative,OSGi)规范,采用插件式模块化的编程思想,将系统框架与功能模块相互分离,同时使模块以插件形式加载实现前后端分离。将设计系统成功推广应用于十余口井,结果表明,系统运行稳定,界面交互方便,数据响应快速,算法维护和版本更新方便快捷,满足了现场应用新需求。该设计思路可为油气领域同类系统的架构设计提供一种有效可靠的思路,对油气井领域系统开发具有借鉴作用。展开更多
Fresh and clean water is highly demanded throughout the world.To effectively address the need,nanomaterials enabled nanotechnology has been explored as a means of more efficient,reliable,and environmentally friendly a...Fresh and clean water is highly demanded throughout the world.To effectively address the need,nanomaterials enabled nanotechnology has been explored as a means of more efficient,reliable,and environmentally friendly approach towards water treatment practices.One concern in adopting nanomaterials is how to retrieve them from water body to avoid secondary contamination.In this work,the earth abundant and sustainable wood,e.g.,basswood,was selected and carbonized into porous carbon as host skeleton,and metal-organic frameworks(MOFs),e.g.,MOF-199 with extremely high surface area,were grown throughout all channels in the porous basswood carbon.Targeting the traditional organic pollutant,methyl orange(MO),the combination of MOFs and basswood carbon(MOFs@carbon)demonstrates a remarkable adsorption capacity,which is 243%and 454%higher than basswood carbon and MOF-199,respectively.Such an outstanding adsorption performance originates from that the positively charged carbon pulls MO molecules close to carbon surface,leading to a high MO molecule concentration,and then the concentration gradient drives the MO molecules to be stored inside MOFs,functioning like pockets.These findings highlight the potential application of coupled MOFs and biomass carbon in addressing water remediation.展开更多
基金financial support from the National Science Foundation of China (Nos. 51374233, 51474235)the Postdoctoral Innovative Project Foundation of Shandong Province (No. 201602027)+2 种基金the Qingdao Postdoctoral Applied Research Project (No. 2015242)the Fundamental Research Funds for the Central Universities (No. 15CX06021A)the Graduate Student Innovation Project from China University of Petroleum (East China) (No. YCX2015011)
文摘Emulsifier-free poly（methyl methacrylate-styrene） [P（MMA-St）] nanospheres with an average particle size of 100 nm were synthesized in an isopropyl alcoholwater medium by a solvothermal method. Then, through radical graft copolymerization of thermo-sensitive mono- mer N-isopropylacrylamide （NIPAm） and hydrophilic monomer acrylic acid （AA） onto the surface of P（MMA- St） nanospheres at 80 ℃, a series of thermo-sensitive polymer nanospheres, named SD-SEAL with different lower critical solution temperatures （LCST）, were prepared by adjusting the mole ratio of NIPAm to AA. The products were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, particle size distribution, and specific surface area analysis. The temperature-sensitive behavior was studied by light transmittance tests, while the sealing performance was investigated by pressure transmission tests with Lungmachi Formation shales. The experimental results showed that the synthesized nanoparticles are sensitive to temperature and had apparent LCST values which increased with an increase in hydrophilic monomer AA. When the temperature was higher than its LCST value, SD- SEAL played a dual role of physical plugging and chemical inhibition, slowed down pressure transmission, and reduced shale permeability remarkably. The plugged layer of shale was changed to being hydrophobic, which greatly improved the shale stability
文摘The fabrication of S-scheme heterojunctions with fast charge transfer and good interface contacts,such as intermolecularπ–πinteractions,is a promising approach to improve photocatalytic performance.A unique two-dimensional/two-dimensional(2D/2D)S-scheme heterojunction containing TpPa-1-COF/g-C_(3)N_(4) nanosheets(denoted as TPCNNS)was developed.The established maximum interfacial interaction between TpPa-1-COF NS and g-C_(3)N_(4) NS may result in aπ–πconjugated heterointerface.Furthermore,the difference in the work functions of TpPa-1-COF and g-C_(3)N_(4) results in a large Fermi level gap,leading to upward/downward band edge bending.The spontaneous interfacial charge transfer from g-C_(3)N_(4) to TpPa-1-COF at theπ–πconjugated interface area results in the presence of a built-in electric field,according to the charge density difference analysis based on density functional theory calculations.Such an enhanced built-in electric field can efficiently drive directional charge migration via the S-scheme mechanism,which enhances charge separation and utilization.Thus,an approximately 2.8 and 5.6 times increase in the photocatalytic hydrogen evolution rate was recorded in TPCNNS-2(1153μmol g^(-1) h^(-1))compared to pristine TpPa-1-COF and g-C_(3)N_(4) NS,respectively,under visible light irradiation.Overall,this work opens new avenues in the fabrication of 2D/2Dπ–πconjugated S-scheme heterojunction photocatalysts with highly efficient hydrogen evolution performance.
基金supported by the National Natural Science Foundation of China (20773104)the Program for New Century Excellent Talents in University (NCET-06-0891)+2 种基金the Key Project of Key Laboratory of Shaanxi Province (08JZ81)the Natural Science Foundation of Hubei Province (2009CBD030)the Important Project of Hubei Provincial Education Office (09HB33)
文摘The complex [Cu2（H2dhbd）2（tpy）2]·CH3OH·4H2O 1 （H4dhbd =2,3-dihydroxybutanedioic acid, tpy = 2,2＇：6＇,2＇＇-terpyridine） has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis. The crystal is of triclinic, space groups Pi with a= 8.6859（17）, b = 11.223（2）, c = 12.275（2）A, α = 112.454（3）, β= 98.435（3）, γ = 105.593（3）°, V= 1022.5（3） A^3, Z = 1, C38H42Cu2N6O18, Mr = 997.86, Dc = 1.621 g/cm^3, μ= 1.127 mm^-1, F（000） = 514, T = 293（2） K, the final R = 0.0539 and wR = 0.1394 for 3550 observed reflections with I 〉 2σ（I）. In the dinuclear unit, two Cun atoms are bridged by two H2dhbd chelate anions, forming a 14-membered ring, in which the distance of Cu…Cu atoms is 7.0526（12）A. Adjacent dinuclear units are constituted through π-π interactions and C-H…O hydrogen-bonding interactions, fashioning the final 3-D supramolecular framework with 1-D open channels. Variable-temperature magnetic susceptibility measurement indicates the presence of weak antiferromagnetic exchange interactions between Cu^II ions.
基金Supported by the Education Committee of Sichuan Province(12ZA090,13CZ0019 and 14ZB0220)Key Laboratory of Green Catalysis of Sichuan Institutes of High Education(LZJ14201)Sichuan University of Science and Engineering(Y2014018)
文摘Two 3D 4-fold interpenetrated metal-organic frameworks, [Mn（L）（bpy）]n （1） and [Cu（HL）（bpy）]n （2）（H3L = 4,4＇,4＇＇-（benzene-1,3,5-triyl-tri（methyleneoxy）） tribenzoic acid, bpy = 4,4′-bipyridine）, were synthesized under hydrothermal conditions, and characterized by element analyses, IR spectra, thermogravimetric analyses, X-ray powder diffraction and magnetic property studies. The single-crystal X-ray analyses revealed that 1 and 2 are homogeneous. 1 crystallizes in monoclinic, space group Cc with a = 26.794（2）, b = 11.6346（10）, c = 21.4614（18） ？, β = 91.570（2）°, V = 6687.9（10） A^3, Z = 8, Mr = 736.59, D = 1.463 g·cm^（-3）, μ = 0.458 mm^-1c, R（int） = 0.0524, F（000） = 3040, the final R = 0.0844 and wR = 0.2266 for 8092 observed reflections（I 〉 2σ（I））. 2 crystallizes in monoclinic, space group Cc with a = 27.609（12）, b = 11.126（10）, c = 21.490（9） ？, β = 92.131（2）°, V = 6597（5） A^3, Z = 8, Mr = 746.21, Dc = 1503 g·cm^（-3）, μ = 0.726 mm^-1, R（int） = 0.0542, F（000） = 3080, the final R =0.0681 and wR = 0.1831 for 6777 observed reflections（I 〉 2σ（I））. Two compounds are 3D [2＋2]-type 4-fold interpenetrated frameworks with（6^3）（6^9.8） hms topology. The magnetic study of compound 2 shows the presence of weak antiferromagnetic interaction between the Cu^Ⅱ ions in 2.
文摘Healthcare security and privacy breaches are occurring in the United States (US), and increased substantially during the pandemic. This paper reviews the National Institute of Standards and Technology (NIST) publication base as an effective solution. The NIST Special Publication 800-66 Revision 1 was an essential standard in US healthcare, which was withdrawn in February 2024 and superseded by SP 800-66 Revision 2. This review investigates the academic papers concerning the application of the NIST SP 800-66 Revision 1 standard in the US healthcare literature. A systematic review method was used in this study to determine current knowledge gaps of the SP 800-66 Revision 1. Some limitations were employed in the search to enforce validity. A total of eleven articles were found eligible for the study. Consequently, this study suggests the necessity for additional academic papers pertaining to SP 800-66 Revision 2 in the US healthcare literature. In turn, it will enhance awareness of safeguarding electronic protected health information (ePHI), help to mitigate potential future risks, and eventually reduce breaches.
基金financially supported by the National Natural Science Foundation of China(No.21201112)
文摘The new ligand 2-（（pyridin-4-ylmethyl）thio）-5-（quinoline-2-yl）-1,3,4-oxadiazole（L） and Ag Cl O4 produced a new coordination polymer： [（Ag2L2Cl O4）ClO 4]n（1）. The complex has been characterized by single-crystal X-ray diffraction, IR, TGA, PXRD, UV and elemental analysis. Compound 1 crystallizes in triclinic system, space group P1, with a = 8.4593（5）, b = 14.5903（9）, c = 15.7908（10） A, α = 97.357（5）, β = 99.116（5）, γ = 104.470（5）°, V = 1834.43（20） A3, Dc = 1.91056 g/cm^3, Mr = 1055.38, Z = 2, F（000） = 1048, u = 1.399 mm-1, the final S = 1.002, R = 0.049 and wR = 0.105. The compound consists of a double helix chain. The neighboring chains interact via two kinds of π-π interactions to form a two-dimensional（2D） sheet. Each sheet interacts with the neighboring sheets via π-π interactions to form an extended 3D supramolecular network.
基金National Science Foundation of China ( No.51032007 and No.U1204505) for supporting this work
文摘Damage reasons of purging plugs for refining ladle and research progress on thermal shock resistance of corundum- spinel purging plugs were summarized. Research achievements and application results of nonoxides bonded corundum purging plugs for refining ladle were briefly reviewed. The further research and developing trend of purging plugs was proposed.
基金Supported by the National Natural Science Foundation of China
文摘The aluminophosphate molecular sieve VPI-5 has received much attention as a new structure containing one-dimensional circular pores circumscribed by 18 tetrahedral atoms. The AlPO;-8 is another new type of structure which was found to contain 1 4-ring open pores. Recently, we have successfully synthesized the molecular sieves of VPI-5 and AlPO;-8, and found that the mixture of VPI-5 and AlPO;-8 was easily formed under similar conditions, and VPI-5 can be converted to AlPO;-8 by dehydration via heating. It is suggested that there exists relationship between the structures of VPI-5 and A1PO;-8. Therefore, the study on the transition and relationship between VPI-5 and A1PO;-8 is very important for designing and preparing new molecular sieves with new structures.
文摘井眼轨道控制系统包括轨道设计、丛式井防碰以及测斜数据分析处理等多个功能模块,需要满足不同井型设计、施工与数据分析的需求,同时要考虑系统可维护性、可扩展性,以满足现场应用的新需求。采用传统设计方法会面临模块化不足、维护升级困难的窘境,因此提出一种基于可扩展框架的井眼轨道控制系统软件。该软件参考开放服务网关协议(Open Service Gateway initiative,OSGi)规范,采用插件式模块化的编程思想,将系统框架与功能模块相互分离,同时使模块以插件形式加载实现前后端分离。将设计系统成功推广应用于十余口井,结果表明,系统运行稳定,界面交互方便,数据响应快速,算法维护和版本更新方便快捷,满足了现场应用新需求。该设计思路可为油气领域同类系统的架构设计提供一种有效可靠的思路,对油气井领域系统开发具有借鉴作用。
基金J.W.W.,Z.Y.C.,and Y.C.Y.acknowledge the financial support from the USDA Forest Service(No.20-JV-11111124-035)Y.C.Y.and P.D.acknowledge the financial support from the Department of the Interior,Bureau of Reclamation(No.R19AC00116)Y.C.Y.thanks Dr.Y.Q.Meng in Idaho National Laboratory for helping on BET measurement.
文摘Fresh and clean water is highly demanded throughout the world.To effectively address the need,nanomaterials enabled nanotechnology has been explored as a means of more efficient,reliable,and environmentally friendly approach towards water treatment practices.One concern in adopting nanomaterials is how to retrieve them from water body to avoid secondary contamination.In this work,the earth abundant and sustainable wood,e.g.,basswood,was selected and carbonized into porous carbon as host skeleton,and metal-organic frameworks(MOFs),e.g.,MOF-199 with extremely high surface area,were grown throughout all channels in the porous basswood carbon.Targeting the traditional organic pollutant,methyl orange(MO),the combination of MOFs and basswood carbon(MOFs@carbon)demonstrates a remarkable adsorption capacity,which is 243%and 454%higher than basswood carbon and MOF-199,respectively.Such an outstanding adsorption performance originates from that the positively charged carbon pulls MO molecules close to carbon surface,leading to a high MO molecule concentration,and then the concentration gradient drives the MO molecules to be stored inside MOFs,functioning like pockets.These findings highlight the potential application of coupled MOFs and biomass carbon in addressing water remediation.
