In order to produceα-calcium sulfate hemihydrate(α-CaSO4·0.5H2O)whiskers with high aspect ratios,a minor amount of CuCl2·2H2O was used as the modifying agent in the process of hydrothermal treatment of cal...In order to produceα-calcium sulfate hemihydrate(α-CaSO4·0.5H2O)whiskers with high aspect ratios,a minor amount of CuCl2·2H2O was used as the modifying agent in the process of hydrothermal treatment of calcium sulfate dihydrate(CaSO4·2H2O)precursor.The presence of 2.60×10–3 mol/L CuCl2·2H2O resulted in the increase of the aspect ratios ofα-CaSO4·0.5H2O whiskers from 81 to 253.The preferential adsorption of Cu2+on the negative{110}and{100}facets ofα-CaSO4·0.5H2O crystal structures was confirmed by EDS and XPS.And ATR-FTIR demonstrated the ligand adsorption of Cu2+on the surface ofα-CaSO4·0.5H2O whiskers.The experimental results reveal that the whiskers with high aspect ratios are attributed to the adsorption of Cu2+,which promotes the 1-D growth ofα-CaSO4·0.5H2O whiskers along the c axis.展开更多
The microstructure of aqueous CuCl2 has been studied through lots of technologies for many years; however, it remains a controversial subject. In this study, a new spectroscopic method has been proposed to analyze the...The microstructure of aqueous CuCl2 has been studied through lots of technologies for many years; however, it remains a controversial subject. In this study, a new spectroscopic method has been proposed to analyze the UV-visible spectra of thin fihn of CuCl2/H2O solutions at different concentrations. This method is the combination of ratio spectra, difference spectra and second order difference spectra. By using this method, two new bands at -230 and -380 nm are obviously observed. The bands are assigned as the contacted ion pairs [CuCl3（H2O）n]- or [CuCl4（H2O）n]2-, which demonstrates that ion pairs exist in the CuCl2/H2O solution. Such finding agrees with the recent theoretical spectra obtained by time-dependent density functional theory. Furthermore, the populations of the contacted ion pairs are discussed. This study not only offers the direct spectroscopic evidence of [CuCl3（H2O）n]- or [CuCl4（H2O）n]2- in aqueous CuCl2, but also suggests that the spec- troscopic analysis method is powerful to extract the weak bands in a strong overlapping spectrum.展开更多
The hydrogenation of CO_(2) into methanol has attracted much attention and In_(2)O_(3) is a promising catalyst.Introducing metal elements into In_(2)O_(3)(M/In_(2)O_(3))is one of the main strategies to improve its per...The hydrogenation of CO_(2) into methanol has attracted much attention and In_(2)O_(3) is a promising catalyst.Introducing metal elements into In_(2)O_(3)(M/In_(2)O_(3))is one of the main strategies to improve its performance.However,its mechanism and active sites remain unclear and need to be further elucidated.Here,the noble‐metal‐free In_(x)‐Co_(y) oxides catalysts were prepared.Much‐improved performance and obvious product selectivity shift were observed.The optimized catalyst(In_(1)‐Co_(4))(9.7 mmol g_(cat)^(–1) h^(–1))showed five times methanol yields than pure In_(2)O_(3)(2.2 mmol g_(cat)^(–1) h^(–1))(P=4.0 MPa,T=300°C,GHSV=24000 cm^(3)_(STP) g_(cat)^(–1) h^(–1),H_(2):CO_(2)=3).And the cobalt‐catalyzed CO_(2) methanation activity was suppressed,although cobalt was most of the metal element.To unravel this selectivity shift,detailed catalysts performance evaluation,together with several in‐situ and ex‐situ characterizations,were employed on cobalt and In‐Co for comparative study.The results indicated CO_(2) hydrogenation on cobalt and In‐Co catalyst both followed the formate pathway,and In‐Co reconstructed and generated a surface In_(2)O_(3)‐enriched core‐shell‐like structure under a reductive atmosphere.The enriched In_(2)O_(3) at the surface significantly enhanced CO_(2) adsorption capacity and well stabilized the intermediates of CO_(2) hydrogenation.CO_(2) and carbon‐containing intermediates adsorbed much stronger on In‐Co than cobalt led to a feasible surface C/H ratio,thus allowing the*CH_(3)O to desorb to produce CH_(3)OH instead of being over‐hydrogenated to CH_(4).展开更多
The nanoparticle coagulation is investigated by using a couple of fluid models and aerosol dynamics model in argon with a 5% molecular acetylene admixture rf microdischarges,with the total input gas flow rate of 400 s...The nanoparticle coagulation is investigated by using a couple of fluid models and aerosol dynamics model in argon with a 5% molecular acetylene admixture rf microdischarges,with the total input gas flow rate of 400 sccm.It co-exists with a homogeneous,secondary electron-dominated low temperature γ-mode glow discharges.The heat transfer equation and flow equation for neutral gas are taken into account.We mainly focused on investigations of the nanoparticle properties in atmospheric pressure microdischarges,and discussed the influences of pressure,electrode spacing,and applied voltage on the plasma density and nanoparticle density profiles.The results show that the characteristics of microdischarges are quite different from those of low pressure radio-frequency discharges.First,the nanoparticle density in the bulk plasma in microdischarges is much larger than that of low pressure discharges.Second,the nanoparticle density of 10 nm experiences an exponential increase as soon as the applied voltage increases,especially in the presheath.Finally,as the electrode spacing increases,the nanoparticle density decreased instead of increasing.展开更多
The potential energy surface of O（^1D）＋C2H5Cl reaction was studied using QCISD（T）/6- 311＋＋G（d,p）//MP2/6-31G（d,p） method. The calculations reveal an insertion-elimination mechanism. The insertion reaction o...The potential energy surface of O（^1D）＋C2H5Cl reaction was studied using QCISD（T）/6- 311＋＋G（d,p）//MP2/6-31G（d,p） method. The calculations reveal an insertion-elimination mechanism. The insertion reaction of O（^1D） and C2H5Cl produces two energy-rich intermediates, IM1 and IM2, which subsequently decompose into various products. The calculations of the branching ratios of various products formed through the two intermediates were carried out using RRKM （Rice-Ramsperger-Kassel-Marcus） theory at the collision energies of 0, 20.9, 41.8, 62.7, 83.6, 104.5, and 125.4 kJ/mol. HCl is the main decomposition product for IM1; CH2OH is the main decomposition product for IM2. Since IM1 is more stable than IM2, HCl is probably the main product of the O（^1D）＋C2H5Cl reaction.展开更多
目的探讨糖尿病视网膜病变(DR)患者餐后2 h血糖(2 h PG)升高对眼底图像中动静脉宽度比(AVR)的影响。方法选取DR患者316例,均行标准75 g口服葡萄糖耐量试验(OGTT)检测空腹血糖(FPG)和餐后2 h PG,根据餐后血糖变化幅度(2 h PG-FPG)将所有...目的探讨糖尿病视网膜病变(DR)患者餐后2 h血糖(2 h PG)升高对眼底图像中动静脉宽度比(AVR)的影响。方法选取DR患者316例,均行标准75 g口服葡萄糖耐量试验(OGTT)检测空腹血糖(FPG)和餐后2 h PG,根据餐后血糖变化幅度(2 h PG-FPG)将所有研究对象按三分位分为3组,低分位组(G1)104例、中分位组(G2)108例及高分位组(G3)104例。测量各组眼底图像中AVR水平,采用Pearson相关性分析和多元线性回归分析DR患者AVR的影响因素。结果 (1)G3组和G2组餐后2 h PG、空腹胰岛素(FIns)、糖化血红蛋白(Hb A1c)及稳态模型评估-胰岛素抵抗指数(HOMA-IR)均高于G1组,且G3组餐后2 h PG和Hb A1c高于G2组;G3组和G2组2 h AVR较G1组降低,G3组较G2组降低(P<0.05),而各组间空腹AVR比较,差异无统计学意义(P>0.05);(2)Pearson相关分析显示,AVR与FPG、餐后2 h PG、Hb A1c、收缩压(SBP)及舒张压(DBP)均呈负相关(P<0.05);(3)多元线性回归分析显示,餐后2 h PG为DR患者AVR的影响因素(P<0.05)。结论餐后2 h PG升高可能会导致AVR降低,对DR患者应动态观察AVR的变化,对判断DR的严重程度具有意义。展开更多
The crystal structure of the title compound（C19H15F3N2O2,Mr = 360.33） was determined by single-crystal X-ray diffraction.The crystal belongs to triclinic,space group P1,with a = 6.5604（7）,b = 13.9614（16）,c = 18....The crystal structure of the title compound（C19H15F3N2O2,Mr = 360.33） was determined by single-crystal X-ray diffraction.The crystal belongs to triclinic,space group P1,with a = 6.5604（7）,b = 13.9614（16）,c = 18.1790（18） ,α = 102.749（7）,β = 97.542（6）,γ = 94.355（4）°,V = 1600.5（3） 3,Z = 4,Dc = 1.495 g/cm3,λ（MoKα） = 0.71070,F（000） = 744,μ（MoKα） = 0.122 mm-1,R = 0.0434 and wR = 0.1051.A total of 7590 unique reflections were collected,of which 5429 with ｜F｜2 ≥ 2σ｜F｜2 were observed.The two cyclohexene rings in the molecule adopt boat-boat conformations with the deviations of ring atoms C（9） and C10 from the C（5）/C（6）/C（7）/C（8） plane（Ⅰ） by 1.1204（0.0023） and 1.1132（0.0023） ,respectively,whereas from the C（2）/C（3）/C（5）/C（8） plane（Ⅱ） by 1.1627（0.0022） and 1.1818（0.0021） ,respectively.In the cyclopropane and lactam rings,atoms C（11） and N（1） point towards the double bond of C（9）-C（10） and the dihedral angle between the ring plane（Ⅲ） containing C（1）,C（2）,C（3） and C（4） and plane（IV） consisting of C（6）,C（7） and C（11） is 55.76（0.07）°.The dihedral angles between planes Ⅳ and Ⅰ and Ⅱ and Ⅲare 63.58（0.07）° and 58.10（0.06）°,respectively.The dihedral angle between the benzene ring C（13）～ C（18） and plane Ⅳ is 42.41（0.06）°.展开更多
Corrections of density effects resulting from air-parcel expansion/compression are important in interpreting eddy covariance fluxes of water vapor and CO2 when open-path systems are used. To account for these effects,...Corrections of density effects resulting from air-parcel expansion/compression are important in interpreting eddy covariance fluxes of water vapor and CO2 when open-path systems are used. To account for these effects, mean vertical velocity and perturbation of the density of dry air are two critical parameters in treating those physical processes responsible for density variations. Based on various underlying assumptions, different studies have obtained different formulas for the mean vertical velocity and perturbation of the density of dry air, leading to a number of approaches to correct density effects. In this study, we re-examine physical processes related to different assumptions that are made to formulate the density effects. Specifically, we re-examine the assumptions of a zero dry air flux and a zero moist air flux in the surface layer, used for treating density variations, and their implications for correcting density effects. It is found that physical processes in relation to the assumption of a zero dry air flux account for the influence of dry air expansion/compression on density variations. Meanwhile, physical processes in relation to the assumption of a zero moist air flux account for the influence of moist air expansion/compression on density variations. In this study, we also re-examine mixing ratio issues. Our results indicate that the assumption of a zero dry air flux favors the use of the mixing ratio relative to dry air, while the assumption of a zero moist air flux favors the use of the mixing ratio relative to the total moist air. Additionally, we compare different formula for the mean vertical velocity, generated by air-parcel expansion/compression, and for density effect corrections using eddy covariance data measured over three boreal ecosystems.展开更多
Methane （CH4） plasma was used to produce amorphous hydrogenated carbon （a- C：H） films by a single capacitively coupled radio frequency （RF） powered plasma system. The system consists of two parallel electrodes...Methane （CH4） plasma was used to produce amorphous hydrogenated carbon （a- C：H） films by a single capacitively coupled radio frequency （RF） powered plasma system. The system consists of two parallel electrodes： the upper electrode is connected to 13.56 MHz RF power and the lower one is connected to the ground. Thin films were deposited on glass slides with different sizes and on silicon wafers. The influence of the plasma species on film characteristics was studied by changing the plasma parameters. The changes of plasma species during the deposition were investigated by optical emission spectroscopy （OES）. The structural and optical properties were analyzed via Fourier transform infrared （FTIR） spectroscopy, X-ray diffraction （XRD） and UV-visible spectroscopy, and the thicknesses of the samples were measured by a profilometer. The sp3/sp2 ratio and the existing H atoms play a significant role in the determination of the chemical properties of thin films in the plasma. The film quality and deposition rate were both increased by raising the power and the flow rate.展开更多
基金Project(B14034)supported by the National 111 Project,ChinaProject(2015CX005)supported by the Innovation Driven Plan of Central South University,ChinaProject(2016zzts104)supported by the Fundamental Research Funds for the Central Universities,China
文摘In order to produceα-calcium sulfate hemihydrate(α-CaSO4·0.5H2O)whiskers with high aspect ratios,a minor amount of CuCl2·2H2O was used as the modifying agent in the process of hydrothermal treatment of calcium sulfate dihydrate(CaSO4·2H2O)precursor.The presence of 2.60×10–3 mol/L CuCl2·2H2O resulted in the increase of the aspect ratios ofα-CaSO4·0.5H2O whiskers from 81 to 253.The preferential adsorption of Cu2+on the negative{110}and{100}facets ofα-CaSO4·0.5H2O crystal structures was confirmed by EDS and XPS.And ATR-FTIR demonstrated the ligand adsorption of Cu2+on the surface ofα-CaSO4·0.5H2O whiskers.The experimental results reveal that the whiskers with high aspect ratios are attributed to the adsorption of Cu2+,which promotes the 1-D growth ofα-CaSO4·0.5H2O whiskers along the c axis.
文摘The microstructure of aqueous CuCl2 has been studied through lots of technologies for many years; however, it remains a controversial subject. In this study, a new spectroscopic method has been proposed to analyze the UV-visible spectra of thin fihn of CuCl2/H2O solutions at different concentrations. This method is the combination of ratio spectra, difference spectra and second order difference spectra. By using this method, two new bands at -230 and -380 nm are obviously observed. The bands are assigned as the contacted ion pairs [CuCl3（H2O）n]- or [CuCl4（H2O）n]2-, which demonstrates that ion pairs exist in the CuCl2/H2O solution. Such finding agrees with the recent theoretical spectra obtained by time-dependent density functional theory. Furthermore, the populations of the contacted ion pairs are discussed. This study not only offers the direct spectroscopic evidence of [CuCl3（H2O）n]- or [CuCl4（H2O）n]2- in aqueous CuCl2, but also suggests that the spec- troscopic analysis method is powerful to extract the weak bands in a strong overlapping spectrum.
文摘The hydrogenation of CO_(2) into methanol has attracted much attention and In_(2)O_(3) is a promising catalyst.Introducing metal elements into In_(2)O_(3)(M/In_(2)O_(3))is one of the main strategies to improve its performance.However,its mechanism and active sites remain unclear and need to be further elucidated.Here,the noble‐metal‐free In_(x)‐Co_(y) oxides catalysts were prepared.Much‐improved performance and obvious product selectivity shift were observed.The optimized catalyst(In_(1)‐Co_(4))(9.7 mmol g_(cat)^(–1) h^(–1))showed five times methanol yields than pure In_(2)O_(3)(2.2 mmol g_(cat)^(–1) h^(–1))(P=4.0 MPa,T=300°C,GHSV=24000 cm^(3)_(STP) g_(cat)^(–1) h^(–1),H_(2):CO_(2)=3).And the cobalt‐catalyzed CO_(2) methanation activity was suppressed,although cobalt was most of the metal element.To unravel this selectivity shift,detailed catalysts performance evaluation,together with several in‐situ and ex‐situ characterizations,were employed on cobalt and In‐Co for comparative study.The results indicated CO_(2) hydrogenation on cobalt and In‐Co catalyst both followed the formate pathway,and In‐Co reconstructed and generated a surface In_(2)O_(3)‐enriched core‐shell‐like structure under a reductive atmosphere.The enriched In_(2)O_(3) at the surface significantly enhanced CO_(2) adsorption capacity and well stabilized the intermediates of CO_(2) hydrogenation.CO_(2) and carbon‐containing intermediates adsorbed much stronger on In‐Co than cobalt led to a feasible surface C/H ratio,thus allowing the*CH_(3)O to desorb to produce CH_(3)OH instead of being over‐hydrogenated to CH_(4).
基金Project supported by the Natural Science Foundation of Heilongjiang Province,China(Grant Nos.A2015011 and A2015010)the Postdoctoral Scientific Research Development Fund of Heilongjiang Province,China(Grant No.LBH-Q14159)+2 种基金the Program for Young Teachers Scientific Research in Qiqihar University(Grant No.2014k-Z11)the National Natural Science Foundation of China(Grant No.11404180)the University Nursing Program for Yong Scholars with Creative Talents in Heilongjiang Province,China(Grant No.UNPYSCT-2015095)
文摘The nanoparticle coagulation is investigated by using a couple of fluid models and aerosol dynamics model in argon with a 5% molecular acetylene admixture rf microdischarges,with the total input gas flow rate of 400 sccm.It co-exists with a homogeneous,secondary electron-dominated low temperature γ-mode glow discharges.The heat transfer equation and flow equation for neutral gas are taken into account.We mainly focused on investigations of the nanoparticle properties in atmospheric pressure microdischarges,and discussed the influences of pressure,electrode spacing,and applied voltage on the plasma density and nanoparticle density profiles.The results show that the characteristics of microdischarges are quite different from those of low pressure radio-frequency discharges.First,the nanoparticle density in the bulk plasma in microdischarges is much larger than that of low pressure discharges.Second,the nanoparticle density of 10 nm experiences an exponential increase as soon as the applied voltage increases,especially in the presheath.Finally,as the electrode spacing increases,the nanoparticle density decreased instead of increasing.
基金ACKNOWLEDGMENT This work was supported Science Foundation of China by the National Natural （No.50772107）.
文摘The potential energy surface of O（^1D）＋C2H5Cl reaction was studied using QCISD（T）/6- 311＋＋G（d,p）//MP2/6-31G（d,p） method. The calculations reveal an insertion-elimination mechanism. The insertion reaction of O（^1D） and C2H5Cl produces two energy-rich intermediates, IM1 and IM2, which subsequently decompose into various products. The calculations of the branching ratios of various products formed through the two intermediates were carried out using RRKM （Rice-Ramsperger-Kassel-Marcus） theory at the collision energies of 0, 20.9, 41.8, 62.7, 83.6, 104.5, and 125.4 kJ/mol. HCl is the main decomposition product for IM1; CH2OH is the main decomposition product for IM2. Since IM1 is more stable than IM2, HCl is probably the main product of the O（^1D）＋C2H5Cl reaction.
文摘目的探讨糖尿病视网膜病变(DR)患者餐后2 h血糖(2 h PG)升高对眼底图像中动静脉宽度比(AVR)的影响。方法选取DR患者316例,均行标准75 g口服葡萄糖耐量试验(OGTT)检测空腹血糖(FPG)和餐后2 h PG,根据餐后血糖变化幅度(2 h PG-FPG)将所有研究对象按三分位分为3组,低分位组(G1)104例、中分位组(G2)108例及高分位组(G3)104例。测量各组眼底图像中AVR水平,采用Pearson相关性分析和多元线性回归分析DR患者AVR的影响因素。结果 (1)G3组和G2组餐后2 h PG、空腹胰岛素(FIns)、糖化血红蛋白(Hb A1c)及稳态模型评估-胰岛素抵抗指数(HOMA-IR)均高于G1组,且G3组餐后2 h PG和Hb A1c高于G2组;G3组和G2组2 h AVR较G1组降低,G3组较G2组降低(P<0.05),而各组间空腹AVR比较,差异无统计学意义(P>0.05);(2)Pearson相关分析显示,AVR与FPG、餐后2 h PG、Hb A1c、收缩压(SBP)及舒张压(DBP)均呈负相关(P<0.05);(3)多元线性回归分析显示,餐后2 h PG为DR患者AVR的影响因素(P<0.05)。结论餐后2 h PG升高可能会导致AVR降低,对DR患者应动态观察AVR的变化,对判断DR的严重程度具有意义。
文摘The crystal structure of the title compound（C19H15F3N2O2,Mr = 360.33） was determined by single-crystal X-ray diffraction.The crystal belongs to triclinic,space group P1,with a = 6.5604（7）,b = 13.9614（16）,c = 18.1790（18） ,α = 102.749（7）,β = 97.542（6）,γ = 94.355（4）°,V = 1600.5（3） 3,Z = 4,Dc = 1.495 g/cm3,λ（MoKα） = 0.71070,F（000） = 744,μ（MoKα） = 0.122 mm-1,R = 0.0434 and wR = 0.1051.A total of 7590 unique reflections were collected,of which 5429 with ｜F｜2 ≥ 2σ｜F｜2 were observed.The two cyclohexene rings in the molecule adopt boat-boat conformations with the deviations of ring atoms C（9） and C10 from the C（5）/C（6）/C（7）/C（8） plane（Ⅰ） by 1.1204（0.0023） and 1.1132（0.0023） ,respectively,whereas from the C（2）/C（3）/C（5）/C（8） plane（Ⅱ） by 1.1627（0.0022） and 1.1818（0.0021） ,respectively.In the cyclopropane and lactam rings,atoms C（11） and N（1） point towards the double bond of C（9）-C（10） and the dihedral angle between the ring plane（Ⅲ） containing C（1）,C（2）,C（3） and C（4） and plane（IV） consisting of C（6）,C（7） and C（11） is 55.76（0.07）°.The dihedral angles between planes Ⅳ and Ⅰ and Ⅱ and Ⅲare 63.58（0.07）° and 58.10（0.06）°,respectively.The dihedral angle between the benzene ring C（13）～ C（18） and plane Ⅳ is 42.41（0.06）°.
文摘Corrections of density effects resulting from air-parcel expansion/compression are important in interpreting eddy covariance fluxes of water vapor and CO2 when open-path systems are used. To account for these effects, mean vertical velocity and perturbation of the density of dry air are two critical parameters in treating those physical processes responsible for density variations. Based on various underlying assumptions, different studies have obtained different formulas for the mean vertical velocity and perturbation of the density of dry air, leading to a number of approaches to correct density effects. In this study, we re-examine physical processes related to different assumptions that are made to formulate the density effects. Specifically, we re-examine the assumptions of a zero dry air flux and a zero moist air flux in the surface layer, used for treating density variations, and their implications for correcting density effects. It is found that physical processes in relation to the assumption of a zero dry air flux account for the influence of dry air expansion/compression on density variations. Meanwhile, physical processes in relation to the assumption of a zero moist air flux account for the influence of moist air expansion/compression on density variations. In this study, we also re-examine mixing ratio issues. Our results indicate that the assumption of a zero dry air flux favors the use of the mixing ratio relative to dry air, while the assumption of a zero moist air flux favors the use of the mixing ratio relative to the total moist air. Additionally, we compare different formula for the mean vertical velocity, generated by air-parcel expansion/compression, and for density effect corrections using eddy covariance data measured over three boreal ecosystems.
基金Supported by National Natural Science Foundation of China(Grant No.51207027)Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry of ChinaUndergraduate Training Programs for Innovation and Entrepreneurship
基金supported by the Scientific Research Project Fund of Duzce University under the projectnumber 2013.05.02.195
文摘Methane （CH4） plasma was used to produce amorphous hydrogenated carbon （a- C：H） films by a single capacitively coupled radio frequency （RF） powered plasma system. The system consists of two parallel electrodes： the upper electrode is connected to 13.56 MHz RF power and the lower one is connected to the ground. Thin films were deposited on glass slides with different sizes and on silicon wafers. The influence of the plasma species on film characteristics was studied by changing the plasma parameters. The changes of plasma species during the deposition were investigated by optical emission spectroscopy （OES）. The structural and optical properties were analyzed via Fourier transform infrared （FTIR） spectroscopy, X-ray diffraction （XRD） and UV-visible spectroscopy, and the thicknesses of the samples were measured by a profilometer. The sp3/sp2 ratio and the existing H atoms play a significant role in the determination of the chemical properties of thin films in the plasma. The film quality and deposition rate were both increased by raising the power and the flow rate.
