The wealth of published material for English language teaching (ELT) available on the market makes selecting the right course book a challenging task. So we need to make an assessment before using a course book in the...The wealth of published material for English language teaching (ELT) available on the market makes selecting the right course book a challenging task. So we need to make an assessment before using a course book in the teaching. Course book analysis and evaluation is also useful in teaching development and helps teachers to gain good and useful insights into the nature of the material. The writer here will introduce the series of the material:New Horizon College English, and then tries to analyze and evaluate mainly on the material of viewing, listening and speaking by combining with the situation of the students in Zunyi Normal College.展开更多
Enrichment of As and Au at the overgrowth rims of arsenian pyrite is a distinctive feature of Carlin-type gold ores.Revealing distribution of such key elements in high resolution is of fundamental importance yet often...Enrichment of As and Au at the overgrowth rims of arsenian pyrite is a distinctive feature of Carlin-type gold ores.Revealing distribution of such key elements in high resolution is of fundamental importance yet often proves challenging.In this study,repeated non-oxidative acid etching of ore samples from Shuiyindong gold deposit was applied to enable elemental depth profiling of goldbearing arsenian pyrite grains.ICP-OES and AAS were used to determine the dissolved Fe,As,and Au concentrations in each of the etching solutions,and XPS was carried out to exam the etched mineral surfaces.In contrast to conventional ion beam etching that may cause substantial sample damage,our acid etching method does not seem to significantly alter the composition and chemical state of the samples.The etched depths directly converted from the measured elemental concentrations can reproducibly reach a very high resolution of~1 nm,and can be conveniently controlled through varying the etching time.While the Fe and As depth profiles consistently reflect the surface oxidation property of arsenian pyrite,the Au profile displaying an obvious upward trend reveals the ore fluid evolution at the late stage of mineralization.Based on our experimental results,we demonstrate that our wet chemistry method is capable of effective depth profiling of gold ore and perhaps other geological samples,with advantages surpassing many instrumental techniques including negligible sample damage,nanoscale resolution as well as isotropic etching.展开更多
Achieving highly-efficient and stable perovskite solar cells(PSCs) with a simplified structure remains challenging, despite the tremendous potential for reducing preparation cost and facile processability by removing ...Achieving highly-efficient and stable perovskite solar cells(PSCs) with a simplified structure remains challenging, despite the tremendous potential for reducing preparation cost and facile processability by removing hole transport layer(HTL). In this work, eco-friendly glucose(Gl) as an interface modifier for HTL-free narrow bandgap tin-lead(Sn-Pb) PSCs is proposed. Gl not only enhances the wettability of the indium tin oxide to promote perovskite heterogeneous nucleation on substrate, but also realizes defect passivation by interacting with uncoordinated Pb^(2+) and Sn^(2+) in perovskite films. As a result, the quality of the perovskite films has been significantly improved, accompanied by reduced defects of bottom interface and optimized energy level structure of device, leading to an efficiency increase and a less nonradiative voltage loss of 0.102 V(for a bandgap of ~1.26 eV). Consequently, the optimized PSC delivers an unprecedented efficiency over 21% with high open-circuit voltage and enhanced stability, outperforming the control device. This work demonstrates a cost-effective approach to develop simplified structure high efficiency HTL-free Sn-Pb PSC.展开更多
Carbon burial in lake sediments is an important component of the global carbon cycle. However, little is known about the magnitude of carbon sequestered in lake sediments over the arid/semiarid region of China(ASAC).I...Carbon burial in lake sediments is an important component of the global carbon cycle. However, little is known about the magnitude of carbon sequestered in lake sediments over the arid/semiarid region of China(ASAC).In this study, we estimate both organic and inorganic carbon burial since *AD 1800 based on nine lakes in ASAC,and discuss the most plausible factors controlling carbon burial. Our estimates show that the annual organic carbon burial rate(OCBR) ranges from 5.3 to 129.8 g cm-2year-1(weighted mean of 49.9 g cm-2year-1), leading to a standing stock of 1.1–24.0 kg cm-2(weighted mean of 8.6 kg cm-2)and a regional sum of *108 Tg organic carbon sequestered since *AD 1800. The annual inorganic carbon burial rate(ICBR) ranges from 11.4 to 124.0 g cm-2year-1(weighted mean of 48.3 g cm-2year-1), which is slightly lower than OCBR. The inorganic carbon standing stock ranges from2.4 to 26.0 kg cm-2(weighted mean of 8.1 kg cm-2),resulting in a sum of *101 Tg regional inorganic carbon burial since *AD 1800, which is slightly lower than the organic carbon sequestration. OCBR in ASAC shows a continuously increasing trend since *AD 1950, which is possibly due to the high autochthonous and allochthonous primary production and subsequently high sedimentation rate in the lakes. This increasing carbon burial is possibly related to both climatic changes and enhanced anthropogenic activities, such as land use change, deforestation, and eutrophication in the lake. Furthermore, OCBR and ICBR are expected to continuously increase under the scenario of increasing precipitation and runoff and enhanced anthropogenic activities.The results of this research show that the buried carbon in lake sediments of the ASAC region constitutes a significant and large carbon pool, which should be considered and integrated into the global carbon cycle.展开更多
Let {Xi}i=1^∞ be a standardized stationary Gaussian sequence with covariance function τ(n) =EX1Xn+1, Sn =∑i=1^nXi,and X^-n=Sn/n.And let Nn be the point process formed by the exceedances of random level (x/√2 l...Let {Xi}i=1^∞ be a standardized stationary Gaussian sequence with covariance function τ(n) =EX1Xn+1, Sn =∑i=1^nXi,and X^-n=Sn/n.And let Nn be the point process formed by the exceedances of random level (x/√2 log n+√2 log n-log(4π log n)/2√log n) √1-τ(n) + X^-n by X1,X2,…, Xn. Under some mild conditions, Nn and Sn are asymptotically independent, and Nn converges weakly to a Poisson process on (0,1].展开更多
In this paper,the authors study some impulsive fractionalorder neural network with mixed delay. By the fractional integral and the definition of stability, the existence of solutions of the network is proved,and the s...In this paper,the authors study some impulsive fractionalorder neural network with mixed delay. By the fractional integral and the definition of stability, the existence of solutions of the network is proved,and the sufficient conditions for stability of the system are presented. Some examples are given to illustrate the main results.展开更多
5-(Hydroxymethyl) isophthalic acid (H2HIA) as a novel organic ligand was prepared from 3,5-bis(methoxycarbonyl)benzoic acid by a two-step method. And then, a 3D helical coor- dination polymer with a 3-fold inter...5-(Hydroxymethyl) isophthalic acid (H2HIA) as a novel organic ligand was prepared from 3,5-bis(methoxycarbonyl)benzoic acid by a two-step method. And then, a 3D helical coor- dination polymer with a 3-fold interpenetration structure, namely [Zn1/2(HIA)1/2(DPEE)1/2]n (1), was hydrothermally synthesized at 160 ℃, using H2HIA ligands to assemble with DPEE ligands and Zn2+ ions. Complex 1 crystalizes in orthorhombic system, space group Pnna, with a = 8.2118(5), b = 17.1698(7), c =14.9922(7) ?, V = 2113.82(18) ?3, μ = 1.194 mm-1, Z = 4 and S = 0.967. Moreover, some physical characteristics of complex 1, such as powder X-ray diffraction (PXRD), thermogravimetry analyses (TGA) and photoluminescent properties, were also investigated.展开更多
As one of the most active rare earths,CeO2 has caused extensive concern due to its multifunctional properties.CeO2-based compound oxide of M2O3-CeO2(M=La,Fe,and Al)were prepared by coprecipitation and impregnation met...As one of the most active rare earths,CeO2 has caused extensive concern due to its multifunctional properties.CeO2-based compound oxide of M2O3-CeO2(M=La,Fe,and Al)were prepared by coprecipitation and impregnation methods.The photocatalytic performance of the samples for the degradation methylene blue was studied under UV and visible light irradiation.The effects of constituents on the properties of the CeO2-based catalysts were investigated by XRD,TEM,BET,and UV-Vis spectrophotometer.The highest degradation of methylene blue under 230W UV light was almost 100%at 50 min by La2O3/Fe2O3-CeO2/γ-Al2O3 catalyst and 99.42%at 50 min by Fe2O3-CeO2/γ-Al2O3 catalyst.The methylene blue removal efficiency under indoor natural light reaches 93.81%by La2O3/Fe2O3-CeO2/γ-Al2O3 catalyst and 92.34%by Fe2O3-CeO2/γ-Al2O3 catalyst at 50 min.The order of catalytic degradation activity is La2O3/Fe2O3-CeO2/γ-Al2O3>Fe2O3-CeO2/γ-Al2O3>La2O3-CeO2/γ-Al2O3>Al2O3,owing to their structural features.The doping of La^3+or Fe3+onto CeO2/γ-Al2O produced much more oxygen vacancies under light irradiation and reduced the energy laps of CeO2 with value of 2.86 ev,which improved the photocatalytic redox performance of the composite oxide.展开更多
Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the levels of trace heavy metals in human urine and sweat, to compare the performance of ICP-MS using three sample processing methods, namely d...Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the levels of trace heavy metals in human urine and sweat, to compare the performance of ICP-MS using three sample processing methods, namely direct dilution, wet digestion, and microwave digestion. The results showed that the wet digestion ICP-MS method has the highest accuracy (relative standard deviation ≤10%) and is more useful for measuring the levels of trace heavy metals in urine and sweat. Hence, we used this method to compare the levels of the five trace heavy metals, namely chromium, copper, zinc, cadmium, and lead, in the urine and sweat of adults after strenuous exercise. The results showed that the levels of these five trace heavy metals in sweat were significantly higher than those in urine after strenuous exercise (The differences between the measurements in urine and those in sweat were significant P ≤ 0.01). The results suggested that exercise-induced sweating can effectively remove the harmful heavy metals from the human body.展开更多
With the help of in-situ formed CH_3COO- anion, a pair of 3D homochiral coordination polymers with open channels were constructed by the assembly of lactic acid derivative ligands, 1.4-DIB ligands and Cd(II) ions, n...With the help of in-situ formed CH_3COO- anion, a pair of 3D homochiral coordination polymers with open channels were constructed by the assembly of lactic acid derivative ligands, 1.4-DIB ligands and Cd(II) ions, namely [Cd3((R)-CIA)2(CH3CO2)_2(1.4-DIB)2(H2O)2]·x(Guest)(1-D) and [Cd3((S)-CIA)2(CH3CO2)2(1.4-DIB)2(H2O)2]·x(Guest)(1-L). They contain 1D interesting ladder-like Cd-(R)-CIA(3-) chains and exhibit SHG-active behavior and photoluminescent property.展开更多
A tunable dual-band stop-band THz spectrum can be realized in a hybrid structure, which consists of metal nanoribbon arrays clad by graphene nanoribbons. Dual-band spectra can be controlled separately by the nanoribbo...A tunable dual-band stop-band THz spectrum can be realized in a hybrid structure, which consists of metal nanoribbon arrays clad by graphene nanoribbons. Dual-band spectra can be controlled separately by the nanoribbon width ω and graphene chemical potential μ_c. We explain that two local plasmonic modes excited at graphene ribbons belong to different gratings, which uncouple with each other by electro-magnetic shielding of the metal ribbons. Furthermore, plasmonic induced transparent(PIT) effects can also be realized by making the two transmission notches close to each other, with better performance than the PIT system based on plasmonic coupling,such as with a larger extinction radio and a tunable transparency window.展开更多
We investigate theoretically the electron transport for a two-level quantum channel (wire) with Rashba spinorbit coupling under the irradiation of a longitudinally-polarized external laser field at low temperatures....We investigate theoretically the electron transport for a two-level quantum channel (wire) with Rashba spinorbit coupling under the irradiation of a longitudinally-polarized external laser field at low temperatures. Using the method of equation of motion for Keldysh nonequilibrium Green function, we examine the time-averaged spin polarized conductance for the system with photon polarization parallel to the wire direction. By analytical analysis and a few numerical examples, the interplay effects of the external laser field and the Rashba spin-orbit coupling on the spinpolarized conductance for the system are demonstrated and discussed. It is found that the longitudinally-polarized laser field can adjust the spin polarization rate and produce some photon sideband resonances of the conductance for the system.展开更多
This paper investigates theoretically the electronic structure and transport of a two-level quantum dot irradiated under a strong laser field at low temperatures. Using the method of Keldysh equation of motion for non...This paper investigates theoretically the electronic structure and transport of a two-level quantum dot irradiated under a strong laser field at low temperatures. Using the method of Keldysh equation of motion for nonequilibrium Green functions, it examines the time-averaged density of states and conductance for the system with photon polarization parallel with and perpendicular to the tunnelling current direction respectively. It is demonstrated that, by analysing some numerical examples, more photon sidebands resonance states and multi-and single-photon transitions are found when diagonal matrix elements dominate the interaction, while the electronic transitions due to multiphoton absorption are more or less suppressed when off-diagonal interaction dominates.展开更多
Four isostructural lanthanide compounds formulated as {[Ln4(μ3-OH)4(L-asp)3- (H2O)10](ClO4)5·10H2O}n (Ln=Nd (1), Sm (2), Eu (3), Gd (4); asp=aspartic acid) were synthe- sized by a conventional ...Four isostructural lanthanide compounds formulated as {[Ln4(μ3-OH)4(L-asp)3- (H2O)10](ClO4)5·10H2O}n (Ln=Nd (1), Sm (2), Eu (3), Gd (4); asp=aspartic acid) were synthe- sized by a conventional solution reaction. Their structures were characterized by single-crystal X-ray diffraction, IR spectroscopy and elemental analyses (EA). It reveals that they crystallize in the chiral P212121 space group. Their structures feature a homochiral three-dimensional (3D) lan- thanide-organic framework, which contains a cubic [Ln4(μ3-OH)4]8+ cluster sub-building unit (SBU). Additionally, the photoluminescence property of Eu compound was investigated in the solid-state at room temperature.展开更多
The chiral sulfide Y4InSbS9 has been prepared from stoichiometric elements at 1223 K in an evacuated silica tube. It crystallizes in the chiral tetragonal space group P43212 with a = 9.8784(3), c = 27.3106(16) A, ...The chiral sulfide Y4InSbS9 has been prepared from stoichiometric elements at 1223 K in an evacuated silica tube. It crystallizes in the chiral tetragonal space group P43212 with a = 9.8784(3), c = 27.3106(16) A, V = 2665.04(19) A^3, Z = 8, Mr = 880.75, Dc = 4.390 g/cm^3, μ = 22.285 mm^–1, F(000) = 3200, the final R = 0.0302 and wR = 0.0669 for 2961 observed reflections with I 〉 2σ(I). The structure features infinite helical chains of [In2Sb2S(11)^10–]∞ propagating along the c direction and they are separated by isolated Y^3+ cations and S2– anions. UV/Vis diffuse reflectance spectroscopy study shows that its optical gap is around 1.94 eV. Density functional theory(DFT) study indicates an indirect band gap with an electronic transfer excitation of S 3p to Y 5d orbital electrons.展开更多
It is commonly accepted that the system undergoes a crossover at high temperature and low chemical potential beyond the chiral limit case, and the properties of the crossover region are important for researchers to un...It is commonly accepted that the system undergoes a crossover at high temperature and low chemical potential beyond the chiral limit case, and the properties of the crossover region are important for researchers to understand the nature of strong interacting matters of quantum chromodynamics (QCD). Since at present there is no exact order of parameters of the phase transitions beyond the chiral limit, QCD susceptibilities are widely used as indicators. In this work various susceptibilities are discussed in the framework of Dyson-Schwinger equations. The results show that different kinds of susceptibilities give the same critical end point, which is the bifurcation point of the crossover region and the first order phase transition line of QCD. Nevertheless, different pseudo- critical points are found in the temperature axis. We think that defining a critical band is more suitable in the crossover region.展开更多
The La2O3/Fe2O3-CeO2 composite oxide catalysts were prepared by coprecipitation method, sol-gel method and hydrothermal method. The effect of preparation methods on structure morphology and photocatalytic properties o...The La2O3/Fe2O3-CeO2 composite oxide catalysts were prepared by coprecipitation method, sol-gel method and hydrothermal method. The effect of preparation methods on structure morphology and photocatalytic properties of La2O3/Fe2O3-CeO2 samples was investigated. The results show that the cubic CeO2 structure can be obtained at 600℃. The rod-shaped sample prepared by coprecipitation method, displays the highest crystalline and the strongest diffraction peak intensity. The spherical sample is acquired from sol-gel method, while the small granular sample prepared by hydrothermal method tends to aggregate. The maximum specific surface area of the sample prepared by coprecipitation method is 76.21 m2/g, the minimum specific area of the sample from sol-gel method is 32.66 m2/g and the maximum pore size is 13.84 nm, while the minimum pore volume and pore size of the sample by hydrothermal method are 0.038 cm3/g and 3.95 nm respectively. The band gap energy of catalyst samples is in the following order: sample-CP < sample-SG < sample-HT. The sample obtained by coprecipitation method has the best catalytic degradation performance for methylene blue. Under the excitation of visible light, the degradation rate was 99.58% at 50 minutes, which was higher than those of sol-gel method and hydrothermal method by 5.58% and 9.54% respectively. The catalytic degradation reaction is a first-order kinetic model: ln (c0/ct) = kt + qe. The maximum k-value of the sample degradation process obtained by coprecipitation method is 0.074 min-1.展开更多
We discuss the chiral phase transition of quantum chromodynamics (QCD) with a chiral chemical potential μ5 as an additional scale. Within the framework of Dyson-Schwinger equations, we focus particularly on the beh...We discuss the chiral phase transition of quantum chromodynamics (QCD) with a chiral chemical potential μ5 as an additional scale. Within the framework of Dyson-Schwinger equations, we focus particularly on the behavior of the widely accepted as well as interesting critical end point (CEP), using a separable gluon propagator and a Gaussian gluon propagator. We find that there may be no CEP5 in the T-μ5 plane, and the phase transition in the T μ5 plane might be totally crossover. Our results have apparent consistency with the Lattice QCD calculation. On the other hand, our study may also provide some useful hints to some other studies related to μ5.展开更多
In this paper, we give a note on the eigenvalue localization sets for tensors. We show that these sets are tighter than those provided by Li et al. (2014) [1].
文摘The wealth of published material for English language teaching (ELT) available on the market makes selecting the right course book a challenging task. So we need to make an assessment before using a course book in the teaching. Course book analysis and evaluation is also useful in teaching development and helps teachers to gain good and useful insights into the nature of the material. The writer here will introduce the series of the material:New Horizon College English, and then tries to analyze and evaluate mainly on the material of viewing, listening and speaking by combining with the situation of the students in Zunyi Normal College.
基金Financial supports from the B-type Strategic Priority Program of the Chinese Academy of Sciences(Grant No.XDB41000000)the National Natural Science Foundation of China(41872046,41902041 and 41173074)the Natural Science Research Project of Education Department of Guizhou Province(No.KY[2018]004)are sincerely acknowledged.
文摘Enrichment of As and Au at the overgrowth rims of arsenian pyrite is a distinctive feature of Carlin-type gold ores.Revealing distribution of such key elements in high resolution is of fundamental importance yet often proves challenging.In this study,repeated non-oxidative acid etching of ore samples from Shuiyindong gold deposit was applied to enable elemental depth profiling of goldbearing arsenian pyrite grains.ICP-OES and AAS were used to determine the dissolved Fe,As,and Au concentrations in each of the etching solutions,and XPS was carried out to exam the etched mineral surfaces.In contrast to conventional ion beam etching that may cause substantial sample damage,our acid etching method does not seem to significantly alter the composition and chemical state of the samples.The etched depths directly converted from the measured elemental concentrations can reproducibly reach a very high resolution of~1 nm,and can be conveniently controlled through varying the etching time.While the Fe and As depth profiles consistently reflect the surface oxidation property of arsenian pyrite,the Au profile displaying an obvious upward trend reveals the ore fluid evolution at the late stage of mineralization.Based on our experimental results,we demonstrate that our wet chemistry method is capable of effective depth profiling of gold ore and perhaps other geological samples,with advantages surpassing many instrumental techniques including negligible sample damage,nanoscale resolution as well as isotropic etching.
基金supported by the National Natural Science Foundation of China (Grant No. 12074321)the Young Science and Technology Talents Development Project of Guizhou Provincial Education Department (Grant No. QJH-KY [2022]012)+2 种基金the Fundamental Research Funds for the Central Universities (Grant No. SWU020019)the Natural Science Foundation of Chongqing (Grant No. cstc2020jcyjmsxmx0648)the Chongqing Graduate Student Research Innovation Project (Grant No. CYB22119)。
文摘Achieving highly-efficient and stable perovskite solar cells(PSCs) with a simplified structure remains challenging, despite the tremendous potential for reducing preparation cost and facile processability by removing hole transport layer(HTL). In this work, eco-friendly glucose(Gl) as an interface modifier for HTL-free narrow bandgap tin-lead(Sn-Pb) PSCs is proposed. Gl not only enhances the wettability of the indium tin oxide to promote perovskite heterogeneous nucleation on substrate, but also realizes defect passivation by interacting with uncoordinated Pb^(2+) and Sn^(2+) in perovskite films. As a result, the quality of the perovskite films has been significantly improved, accompanied by reduced defects of bottom interface and optimized energy level structure of device, leading to an efficiency increase and a less nonradiative voltage loss of 0.102 V(for a bandgap of ~1.26 eV). Consequently, the optimized PSC delivers an unprecedented efficiency over 21% with high open-circuit voltage and enhanced stability, outperforming the control device. This work demonstrates a cost-effective approach to develop simplified structure high efficiency HTL-free Sn-Pb PSC.
基金funded by the Chinese Academy of Science (CAS) Strategic Priority Research Program (Grant No. XDA05120404)the National Basic Research Program of China (No. 2013CB955903)+1 种基金the State Key Laboratory of Loess and Quaternary Geology (No. SKLLQG1406)the Western Light Talent Culture Project of CAS
文摘Carbon burial in lake sediments is an important component of the global carbon cycle. However, little is known about the magnitude of carbon sequestered in lake sediments over the arid/semiarid region of China(ASAC).In this study, we estimate both organic and inorganic carbon burial since *AD 1800 based on nine lakes in ASAC,and discuss the most plausible factors controlling carbon burial. Our estimates show that the annual organic carbon burial rate(OCBR) ranges from 5.3 to 129.8 g cm-2year-1(weighted mean of 49.9 g cm-2year-1), leading to a standing stock of 1.1–24.0 kg cm-2(weighted mean of 8.6 kg cm-2)and a regional sum of *108 Tg organic carbon sequestered since *AD 1800. The annual inorganic carbon burial rate(ICBR) ranges from 11.4 to 124.0 g cm-2year-1(weighted mean of 48.3 g cm-2year-1), which is slightly lower than OCBR. The inorganic carbon standing stock ranges from2.4 to 26.0 kg cm-2(weighted mean of 8.1 kg cm-2),resulting in a sum of *101 Tg regional inorganic carbon burial since *AD 1800, which is slightly lower than the organic carbon sequestration. OCBR in ASAC shows a continuously increasing trend since *AD 1950, which is possibly due to the high autochthonous and allochthonous primary production and subsequently high sedimentation rate in the lakes. This increasing carbon burial is possibly related to both climatic changes and enhanced anthropogenic activities, such as land use change, deforestation, and eutrophication in the lake. Furthermore, OCBR and ICBR are expected to continuously increase under the scenario of increasing precipitation and runoff and enhanced anthropogenic activities.The results of this research show that the buried carbon in lake sediments of the ASAC region constitutes a significant and large carbon pool, which should be considered and integrated into the global carbon cycle.
基金Supported by the Program for Excellent Talents in Chongqing Higher Education Institutions (120060-20600204)
文摘Let {Xi}i=1^∞ be a standardized stationary Gaussian sequence with covariance function τ(n) =EX1Xn+1, Sn =∑i=1^nXi,and X^-n=Sn/n.And let Nn be the point process formed by the exceedances of random level (x/√2 log n+√2 log n-log(4π log n)/2√log n) √1-τ(n) + X^-n by X1,X2,…, Xn. Under some mild conditions, Nn and Sn are asymptotically independent, and Nn converges weakly to a Poisson process on (0,1].
基金National Natural Science Foundation of China(No.71461027)Research Fund for the Doctoral Program of Zunyi Normal College,China(No.201419)Guizhou Science and Technology Mutual Fund,China(No.[2015]7002)
文摘In this paper,the authors study some impulsive fractionalorder neural network with mixed delay. By the fractional integral and the definition of stability, the existence of solutions of the network is proved,and the sufficient conditions for stability of the system are presented. Some examples are given to illustrate the main results.
基金supported by the Natural Science Foundation of Guizhou Province(20122344)125 program of Guizhou Education Department(2012015)the Doctoral Scientific Fund of Zunyi Normal College(2012BSJJ12)
文摘5-(Hydroxymethyl) isophthalic acid (H2HIA) as a novel organic ligand was prepared from 3,5-bis(methoxycarbonyl)benzoic acid by a two-step method. And then, a 3D helical coor- dination polymer with a 3-fold interpenetration structure, namely [Zn1/2(HIA)1/2(DPEE)1/2]n (1), was hydrothermally synthesized at 160 ℃, using H2HIA ligands to assemble with DPEE ligands and Zn2+ ions. Complex 1 crystalizes in orthorhombic system, space group Pnna, with a = 8.2118(5), b = 17.1698(7), c =14.9922(7) ?, V = 2113.82(18) ?3, μ = 1.194 mm-1, Z = 4 and S = 0.967. Moreover, some physical characteristics of complex 1, such as powder X-ray diffraction (PXRD), thermogravimetry analyses (TGA) and photoluminescent properties, were also investigated.
基金the National Natural Science Foundation of China(No.41763008)the National Science Foundation of Hunan Province(No.2018JJ2112)+1 种基金the Qian Jiao He KY(2019114)the Talents of Qian Ke He Platform(20175727-11)。
文摘As one of the most active rare earths,CeO2 has caused extensive concern due to its multifunctional properties.CeO2-based compound oxide of M2O3-CeO2(M=La,Fe,and Al)were prepared by coprecipitation and impregnation methods.The photocatalytic performance of the samples for the degradation methylene blue was studied under UV and visible light irradiation.The effects of constituents on the properties of the CeO2-based catalysts were investigated by XRD,TEM,BET,and UV-Vis spectrophotometer.The highest degradation of methylene blue under 230W UV light was almost 100%at 50 min by La2O3/Fe2O3-CeO2/γ-Al2O3 catalyst and 99.42%at 50 min by Fe2O3-CeO2/γ-Al2O3 catalyst.The methylene blue removal efficiency under indoor natural light reaches 93.81%by La2O3/Fe2O3-CeO2/γ-Al2O3 catalyst and 92.34%by Fe2O3-CeO2/γ-Al2O3 catalyst at 50 min.The order of catalytic degradation activity is La2O3/Fe2O3-CeO2/γ-Al2O3>Fe2O3-CeO2/γ-Al2O3>La2O3-CeO2/γ-Al2O3>Al2O3,owing to their structural features.The doping of La^3+or Fe3+onto CeO2/γ-Al2O produced much more oxygen vacancies under light irradiation and reduced the energy laps of CeO2 with value of 2.86 ev,which improved the photocatalytic redox performance of the composite oxide.
基金Supported by the National Natural Science Foundation of China under Grant No 10574042, and the Guizhou Provincial Science and Technology Foundation of China under Grant No 20052088.
文摘Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the levels of trace heavy metals in human urine and sweat, to compare the performance of ICP-MS using three sample processing methods, namely direct dilution, wet digestion, and microwave digestion. The results showed that the wet digestion ICP-MS method has the highest accuracy (relative standard deviation ≤10%) and is more useful for measuring the levels of trace heavy metals in urine and sweat. Hence, we used this method to compare the levels of the five trace heavy metals, namely chromium, copper, zinc, cadmium, and lead, in the urine and sweat of adults after strenuous exercise. The results showed that the levels of these five trace heavy metals in sweat were significantly higher than those in urine after strenuous exercise (The differences between the measurements in urine and those in sweat were significant P ≤ 0.01). The results suggested that exercise-induced sweating can effectively remove the harmful heavy metals from the human body.
基金supported by the Natural Science Foundation of Guizhou Province(20122344)125 program of Guizhou Education Department(2012015)the Doctoral Scientific Fund of Zunyi Normal College(2012BSJJ12)
文摘With the help of in-situ formed CH_3COO- anion, a pair of 3D homochiral coordination polymers with open channels were constructed by the assembly of lactic acid derivative ligands, 1.4-DIB ligands and Cd(II) ions, namely [Cd3((R)-CIA)2(CH3CO2)_2(1.4-DIB)2(H2O)2]·x(Guest)(1-D) and [Cd3((S)-CIA)2(CH3CO2)2(1.4-DIB)2(H2O)2]·x(Guest)(1-L). They contain 1D interesting ladder-like Cd-(R)-CIA(3-) chains and exhibit SHG-active behavior and photoluminescent property.
基金Supported by the Key Disciplines of Physics of Guizhou Province under Grant No QXWB[2013]18the Major Research Projects for Innovation Groups of Guizhou Province under Grant No KY[2018]028+4 种基金the National Natural Science Foundation of China under Grant No 11464052the Science and Technology Foundation of Guizhou Province under Grant No J[2015]2149the Youth Foundation of the Education Department of Guizhou Province under Grant No KY[2017]248the Startup Foundation for Doctors of Zunyi Normal University under Grant No 40300326the Natural Science Foundation of Jiangxi Province under Grant No 20161BAB201002
文摘A tunable dual-band stop-band THz spectrum can be realized in a hybrid structure, which consists of metal nanoribbon arrays clad by graphene nanoribbons. Dual-band spectra can be controlled separately by the nanoribbon width ω and graphene chemical potential μ_c. We explain that two local plasmonic modes excited at graphene ribbons belong to different gratings, which uncouple with each other by electro-magnetic shielding of the metal ribbons. Furthermore, plasmonic induced transparent(PIT) effects can also be realized by making the two transmission notches close to each other, with better performance than the PIT system based on plasmonic coupling,such as with a larger extinction radio and a tunable transparency window.
基金Project supported by the National Natural Science Foundation of China (Grant No 10574042), and the Hunan Provincial Natural Science Foundation of China (Grant No 06JJ2097).
文摘We investigate theoretically the electron transport for a two-level quantum channel (wire) with Rashba spinorbit coupling under the irradiation of a longitudinally-polarized external laser field at low temperatures. Using the method of equation of motion for Keldysh nonequilibrium Green function, we examine the time-averaged spin polarized conductance for the system with photon polarization parallel to the wire direction. By analytical analysis and a few numerical examples, the interplay effects of the external laser field and the Rashba spin-orbit coupling on the spinpolarized conductance for the system are demonstrated and discussed. It is found that the longitudinally-polarized laser field can adjust the spin polarization rate and produce some photon sideband resonances of the conductance for the system.
基金Project supported by the National Natural Science Foundation of China (Grant No 10574042) and the Guizhou Provincial Science and Technology Foundation of China (Grant No 20052088).
文摘This paper investigates theoretically the electronic structure and transport of a two-level quantum dot irradiated under a strong laser field at low temperatures. Using the method of Keldysh equation of motion for nonequilibrium Green functions, it examines the time-averaged density of states and conductance for the system with photon polarization parallel with and perpendicular to the tunnelling current direction respectively. It is demonstrated that, by analysing some numerical examples, more photon sidebands resonance states and multi-and single-photon transitions are found when diagonal matrix elements dominate the interaction, while the electronic transitions due to multiphoton absorption are more or less suppressed when off-diagonal interaction dominates.
基金supported by the Science and Technology Department of Guizhou Province (No. J[2010]2121)Zunyi Science and Technology Bureau (No. [2010]04)
文摘Four isostructural lanthanide compounds formulated as {[Ln4(μ3-OH)4(L-asp)3- (H2O)10](ClO4)5·10H2O}n (Ln=Nd (1), Sm (2), Eu (3), Gd (4); asp=aspartic acid) were synthe- sized by a conventional solution reaction. Their structures were characterized by single-crystal X-ray diffraction, IR spectroscopy and elemental analyses (EA). It reveals that they crystallize in the chiral P212121 space group. Their structures feature a homochiral three-dimensional (3D) lan- thanide-organic framework, which contains a cubic [Ln4(μ3-OH)4]8+ cluster sub-building unit (SBU). Additionally, the photoluminescence property of Eu compound was investigated in the solid-state at room temperature.
基金Supported by the National Natural Science Foundation of China(Nos.21201185 and 21661037)the Natural Science Foundation of Chongqing(Nos.cstc2013jcyjA50033 and cstc2015jcyjA0317)+2 种基金the Natural Science Foundation of Guizhou Province(Nos.JLKZS[2014]13 and[2014]42)the Project Foundation of Chongqing University of Education(No.16xjpt08)the Natural Science Foundation of State Key Laboratory of Structural Chemistry(No.20140004)
文摘The chiral sulfide Y4InSbS9 has been prepared from stoichiometric elements at 1223 K in an evacuated silica tube. It crystallizes in the chiral tetragonal space group P43212 with a = 9.8784(3), c = 27.3106(16) A, V = 2665.04(19) A^3, Z = 8, Mr = 880.75, Dc = 4.390 g/cm^3, μ = 22.285 mm^–1, F(000) = 3200, the final R = 0.0302 and wR = 0.0669 for 2961 observed reflections with I 〉 2σ(I). The structure features infinite helical chains of [In2Sb2S(11)^10–]∞ propagating along the c direction and they are separated by isolated Y^3+ cations and S2– anions. UV/Vis diffuse reflectance spectroscopy study shows that its optical gap is around 1.94 eV. Density functional theory(DFT) study indicates an indirect band gap with an electronic transfer excitation of S 3p to Y 5d orbital electrons.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11275097,11475085,11535005,and 11265017the Jiangsu Planned Projects for Postdoctoral Research Funds under Grant No 1402006C+2 种基金the China Postdoctoral Science Foundation under Grant No 2015M571728the Natural Science Foundation of Jiangsu Province under Grant No BK20130078the Guizhou-Provincial Outstanding Youth Science and Technology Talent Cultivation Object Special Funds under Grant No QKHRZ(2013)28
文摘It is commonly accepted that the system undergoes a crossover at high temperature and low chemical potential beyond the chiral limit case, and the properties of the crossover region are important for researchers to understand the nature of strong interacting matters of quantum chromodynamics (QCD). Since at present there is no exact order of parameters of the phase transitions beyond the chiral limit, QCD susceptibilities are widely used as indicators. In this work various susceptibilities are discussed in the framework of Dyson-Schwinger equations. The results show that different kinds of susceptibilities give the same critical end point, which is the bifurcation point of the crossover region and the first order phase transition line of QCD. Nevertheless, different pseudo- critical points are found in the temperature axis. We think that defining a critical band is more suitable in the crossover region.
文摘The La2O3/Fe2O3-CeO2 composite oxide catalysts were prepared by coprecipitation method, sol-gel method and hydrothermal method. The effect of preparation methods on structure morphology and photocatalytic properties of La2O3/Fe2O3-CeO2 samples was investigated. The results show that the cubic CeO2 structure can be obtained at 600℃. The rod-shaped sample prepared by coprecipitation method, displays the highest crystalline and the strongest diffraction peak intensity. The spherical sample is acquired from sol-gel method, while the small granular sample prepared by hydrothermal method tends to aggregate. The maximum specific surface area of the sample prepared by coprecipitation method is 76.21 m2/g, the minimum specific area of the sample from sol-gel method is 32.66 m2/g and the maximum pore size is 13.84 nm, while the minimum pore volume and pore size of the sample by hydrothermal method are 0.038 cm3/g and 3.95 nm respectively. The band gap energy of catalyst samples is in the following order: sample-CP < sample-SG < sample-HT. The sample obtained by coprecipitation method has the best catalytic degradation performance for methylene blue. Under the excitation of visible light, the degradation rate was 99.58% at 50 minutes, which was higher than those of sol-gel method and hydrothermal method by 5.58% and 9.54% respectively. The catalytic degradation reaction is a first-order kinetic model: ln (c0/ct) = kt + qe. The maximum k-value of the sample degradation process obtained by coprecipitation method is 0.074 min-1.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11275097,11475085,11265017,and 11247219the Jiangsu Planned Projects for Postdoctoral Research Funds under Grant No 1402006C+1 种基金the Natural Science Foundation of Jiangsu Province under Grant No BK20130078the Guizhou Province Outstanding Youth Science and Technology Talent Cultivation Object Special Funds under Grant No QKHRZ(2013)28
文摘We discuss the chiral phase transition of quantum chromodynamics (QCD) with a chiral chemical potential μ5 as an additional scale. Within the framework of Dyson-Schwinger equations, we focus particularly on the behavior of the widely accepted as well as interesting critical end point (CEP), using a separable gluon propagator and a Gaussian gluon propagator. We find that there may be no CEP5 in the T-μ5 plane, and the phase transition in the T μ5 plane might be totally crossover. Our results have apparent consistency with the Lattice QCD calculation. On the other hand, our study may also provide some useful hints to some other studies related to μ5.
文摘In this paper, we give a note on the eigenvalue localization sets for tensors. We show that these sets are tighter than those provided by Li et al. (2014) [1].