The autotetraploid Carassius auratus(4nRR,4n=200,RRRR)is derived from whole-genome duplication of Carassius auratus red var.(RCC,2n=100,RR).In the current study,we demonstrated that chromatophores and pigment changes ...The autotetraploid Carassius auratus(4nRR,4n=200,RRRR)is derived from whole-genome duplication of Carassius auratus red var.(RCC,2n=100,RR).In the current study,we demonstrated that chromatophores and pigment changes directly caused the coloration and variation of 4nRR skin(red in RCC,brownish-yellow in4nRR).To further explore the molecular mechanisms underlying coloration formation and variation in 4nRR,we performed transcriptome profiling and molecular functional verification in RCC and 4nRR.Results revealed that scarb1,associated with carotenoid metabolism,underwent significant down-regulation in 4nRR.Efficient editing of this candidate pigment gene provided clear evidence of its significant role in RCC coloration.Subsequently,we identified four divergent scarb1 homeologs in 4nRR:two original scarb1 homeologs from RCC and two duplicated ones.Notably,three of these homeologs possessed two highly conserved alleles,exhibiting biased and allelespecific expression in the skin.Remarkably,after precise editing of both the original and duplicated scarb1homeologs and/or alleles,4nRR individuals,whether singly or multiply mutated,displayed a transition from brownishyellow skin to a cyan-gray phenotype.Concurrently,the proportional areas of the cyan-gray regions displayed a gene-dose correlation.These findings illustrate the subfunctionalization of duplicated scarb1,with all scarb1genes synergistically and equally contributing to the pigmentation of 4nRR.This is the first report concerning the functional differentiation of duplicated homeologs in an autopolyploidfish,substantiallyenrichingour understanding of coloration formation and change within this group of organisms.展开更多
The SRI analysis tool was used to comprehensively analyze the seven sets of chemistry questions in the 2021 college entrance examination paper from multiple dimensions such as exploratory test questions,various inquir...The SRI analysis tool was used to comprehensively analyze the seven sets of chemistry questions in the 2021 college entrance examination paper from multiple dimensions such as exploratory test questions,various inquiry standards and exploratory levels.The study found that all test papers involve the examination of scientific inquiry literacy;from the perspective of examination objectives,the 2021 college entrance examination questions as a whole focus on the examination of a single inquiry objective;the questions of each examination paper mainly examine three standards:design scheme,evidence processing and obtaining.The conclusion is drawn;the exploratory level of the chemistry questions in several sets of test papers is mostly a high level.展开更多
N decyl 1, 3 diaminopropanes (DNs) were synthesized from alkyl amine acrylonitrile at ambient pressure. With the synthesized DNs as collectors, the flotation of kaolinite, pyrophyllite and illite was conducted and the...N decyl 1, 3 diaminopropanes (DNs) were synthesized from alkyl amine acrylonitrile at ambient pressure. With the synthesized DNs as collectors, the flotation of kaolinite, pyrophyllite and illite was conducted and the results were interpreted in terms of the structure activity relationship. The DNs are found to be more effective collectors than dodecyl amine, exhibiting the highest recovery over a pH range of 46. Among the DNs examined, DN 12 shows the highest flotation efficiency. The flotation mechanisms were explained in view of the structures of reagents and aluminium silicate minerals. It is demonstrated that DNs can become new selective collectors for reverse floatation to remove aluminium silicate minerals from bauxite.展开更多
Nanophosphor with the nominal composition of Ca0.8 Zn0.2 TiO3 : Pr3 + , Na^+ (CZTOPN) was synthesized at relatively low temperature by the sol-gel method. Metal ions were dispersed by citric acid in ethylene glyc...Nanophosphor with the nominal composition of Ca0.8 Zn0.2 TiO3 : Pr3 + , Na^+ (CZTOPN) was synthesized at relatively low temperature by the sol-gel method. Metal ions were dispersed by citric acid in ethylene glycol solvent and then react with Ti(OC4H9)4 to form sol and gel. The decomposition process of the precursor, and crystallization and particle size of CZTOPN were examined by thermal analysis (TG-DSC), powder X-ray diffraction (XRD), and scan election microscopy (SEM). Results of TG-DSC and XRD reveal that the composition of Ca0.8 Zn0.2 TiO3 : Pr3 + , Na^+ changes with the sintering temperature. SEM data indicate that the diameter of particles is under 50 nm even if the sintering temperature increases to 1000 ℃. In contrast to a solid state reaction, the excitation spectra of samples synthesized by the sol-gel method shift blue about 10 nm and the emission intensity at 617 nm increases significantly.展开更多
Two single and double chain manganese coordination polymers {[Mn(L1)(H_2O)_2]NO_3}_n(1) and [Mn(L2)_2(H_2O)]_n(2)(HL1 = 2,2?:6?,2??-terpyridine-4?-carboxylic acid, HL2 = 4?-(4-carboxyphenyl)-2,2?:6?,2??-terpyridine) h...Two single and double chain manganese coordination polymers {[Mn(L1)(H_2O)_2]NO_3}_n(1) and [Mn(L2)_2(H_2O)]_n(2)(HL1 = 2,2?:6?,2??-terpyridine-4?-carboxylic acid, HL2 = 4?-(4-carboxyphenyl)-2,2?:6?,2??-terpyridine) have been synthesized hydrothermally, and characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Compound 1 crystallizes in monoclinic space group P2/c, while 2 crystallizes in triclinic, space group P1. Crystal data for 1: C_(16)H_(14)MnN_4O_7, Mr = 429.25, a = 10.684(2), b = 9.338(1), c = 9.896(2) ?, β = 113.89(3)o, V = 902.7(3) ?~3, Z = 2, T = 153(2) K, Dc = 1.579 g/cm^3, μ = 0.780 mm-1, F(000) = 438, R = 0.1084, wR = 0.3507, and GOF = 1.069; For 2: C44 H30 MnN6 O5, Mr = 777.68, a = 11.255(2), b = 11.554(2), c = 15.417(3) ?, α = 107.28(3), β = 101.07(3), γ = 107.23(3)o, V = 1740.2(6) ?~3, Z = 2, T = 293(2) K, Dc = 1.484 g/cm3, μ = 0.440 mm^(-1), F(000) = 802, R = 0.0471, wR = 0.1050, and GOF = 0.948. In both compounds, the central Mn(Ⅱ) ions adopt the same distorted pentagonal-bipyramid geometry [MnN_3O_4] with different secondary structure units. L1 ligand adopts the μ_2-1κ~3N,N?,N??:2κ~2O,O? mode to coordinate with mononuclear manganese to build a single chainlike compound 1, while L2 employs μ_3-1κ~3N,N?,N??:2κ~2O,O?:3κ~1O and 1κ~1O modes to link dimeric Mn_2O_2 to exhibit a double chainlike 2. Both compounds display weak antiferromagnetic coupling interactions.展开更多
Two new lanthanide coordination polymers, namely [Ln2(μ3-OH)(pydca)-(pyba)3(H2O)]n(Ln = Pr, 1; Eu, 2; Hpyba = 4-(4-pyridyl)benzoic acid; H2 pydca = 2,6-pyridinedicarboxylic acid), have been hydrothermally...Two new lanthanide coordination polymers, namely [Ln2(μ3-OH)(pydca)-(pyba)3(H2O)]n(Ln = Pr, 1; Eu, 2; Hpyba = 4-(4-pyridyl)benzoic acid; H2 pydca = 2,6-pyridinedicarboxylic acid), have been hydrothermally synthesized and characterized by IR spectroscopy and X-ray single-crystal diffraction. The chains of 1 and 2 are constructed by tetrametallic units of [Ln4(OH)2(pyba)2], which are further linked by μ4-k1N, k1O, k2O′, k2O″-pydca and μ2-k1N, k1O, k1O′-pyba to form 2D frameworks. Luminescence measurement reveals that compound 2 exhibits strong reddish emission at room temperature.展开更多
Simultaneously realizing improved activity and stability of acidic oxygen evolution reaction(OER) electrocatalysts is highly promising for developing cost-effective sustainable energy in the splitting of water techniq...Simultaneously realizing improved activity and stability of acidic oxygen evolution reaction(OER) electrocatalysts is highly promising for developing cost-effective sustainable energy in the splitting of water technique.Herein,we report iridium nanocrystals embedded into 3D conductive clothes(Ir-NCT/CC) as a low iridium electrocatalyst realizing ultrahigh acidic OER activity and robust stability.The well-designed Ir-NCT/CC requires a low overpotential of 202 mV to reach the current density of 10 mA cm^(-2)with a high mass activity of 1754 A g^(-1).Importantly,in acidic overall water splitting,Ir-NCT/CC merely delivers a cell voltage of 1.469 V at a typical current density of 10 mA cm^(-2)and also maintains robust durability under continuous operation.We identify that a low working voltage drives the formation of a highly stable amorphous IrOxactive phase over the surface of Ir nanocrystals(surface heterojunction IrOx/Ir-NCT) during operating conditions,which contributes to an effective and durable OER process.展开更多
Fe3O4 magnetic nanoparticles with diameters varying from 10 to 426 nm were synthesized and characterized.Heating effects of Fe3O4 magnetic nanoparticles under radiofrequency capacitive field(RCF) with frequency of 27....Fe3O4 magnetic nanoparticles with diameters varying from 10 to 426 nm were synthesized and characterized.Heating effects of Fe3O4 magnetic nanoparticles under radiofrequency capacitive field(RCF) with frequency of 27.12 MHz and power of 60-150 W were investigated.When the power of RCF is lower than 90 W,temperatures of Fe3O4 magnetic nanoparticles(75-150 mg/mL) can be raised and maximal temperatures are all lower than 50 ℃.When the power of RCF is 90-150 W,temperatures of Fe3O4 magnetic nanoparticles can be quickly raised and are all obviously higher than those of normal saline and distilled water under the same conditions.Temperature of Fe3O4 magnetic nanoparticles can even reach 70.2 ℃ under 150 W RCF.Heating effects of Fe3O4 magnetic nanoparticles are related to RCF power,particle size and particle concentration.展开更多
The quartz crystal microbalance (QCM) was used to monitor the one-day incubation of human breast cancer cells (MCF-7) on the gold electrode. In combination with an optical microscope simulation experiment, the cel...The quartz crystal microbalance (QCM) was used to monitor the one-day incubation of human breast cancer cells (MCF-7) on the gold electrode. In combination with an optical microscope simulation experiment, the cell-population pictures at various stages, the QCM responses to the cells' adhesion, spreading and proliferation on the electrode surface were discussed. The △f0 and △R1 responses were found mainly from mixed effects of viscodensity and surface stress, and in proportion to the cell coverage, rather than to the number of cells at the electrode. The significant fore-and-aft changes in cyclic voltammetry and electrochemical impedance spectroscopy of the ferri-ferrocyanide redox couple also proved that the cells were adhesion to the gold surface.展开更多
A hydrophilic/hydrophobic interpenetrating polymer network (IPN) of poly (vinyl alcohol) / polystyrene was prepared by conversion of the IPN of poly (vinyl acetate)/polystyrene. The hydrophilic/hydrophobic IPN w...A hydrophilic/hydrophobic interpenetrating polymer network (IPN) of poly (vinyl alcohol) / polystyrene was prepared by conversion of the IPN of poly (vinyl acetate)/polystyrene. The hydrophilic/hydrophobic IPN was characterized by FT-IR and DSC, and the swelling ratios of the IPN in different solvents were measured.展开更多
A new electrochemical oscillatory system of bromate in alkaline solution is reported.In Pt-Bromate-Alkaline solution system,two different types of electrochemical oscillations(Type Ⅰ and Type Ⅱ) can be observed.Type...A new electrochemical oscillatory system of bromate in alkaline solution is reported.In Pt-Bromate-Alkaline solution system,two different types of electrochemical oscillations(Type Ⅰ and Type Ⅱ) can be observed.Type Ⅰ appears before hydrogen evolution and Type Ⅱ involves periodic hydrogen evolution.Type Ⅰ relates to the adsorption/desorption of the hydrogen on platinum electrode,and Type Ⅱ with periodic oscillation stems from the coupling of electrochemical reactions(the reduction of bromate and evolution hydrogen reaction) with mass transfer(diffusion and convection).More over,under the right conditions,the two types appear in different oscillatory modes,for example,simple periodical mode and mixed one,etc..Crossed cycle in the cyclic voltammograms,which is the basic characteristics for electrochemical oscillatory systems,has also been observed as expected.展开更多
The luminescent properties of glasses synthesized in air atmosphere by conventional high temperature process were studied. The emissions spectra of Eu2+ and Eu3+ were observed in BaO-La2O3-B2O3-Eu2O3 glasses. The resu...The luminescent properties of glasses synthesized in air atmosphere by conventional high temperature process were studied. The emissions spectra of Eu2+ and Eu3+ were observed in BaO-La2O3-B2O3-Eu2O3 glasses. The results show that the broad emission peaks at 430 nm correspond to 5d→4f emission transition of Eu2+, the sharp emission peaks at 592, 616, 650 and 750 nm correspond to 5D0→7Fj(j=1-4) emission transition of Eu3+, respectively, which indicates that the BaO-La2O3-B2O3-Eu2O3 glass can convert ultraviolet and green components of sunlight into blue and red light so as to increase the intensity of blue and red light, respectively. The luminescent intensity of Eu2+ increases with increasing the molar ratio of Tb3+ in BaO-La2O3-B2O3-Eu2O3-Tb4O7 glasses, whereas the luminescent intensity of Eu3+ decreases. So the luminescent intensity of Eu(III, II) is influenced by Tb3+. These phenomena can be explained by electron transfer mechanism: Eu3+(4f6)+Tb3+(4f8)→Eu2+(4f7)+Tb4+(4f7). Taking advantage of the luminescent properties of BaO-La2O3-B2O3-Eu2O3 glasses, light-conversion glass for agriculture can be produced.展开更多
Graphitic carbon nitride(g-C_(3)N_(4)) is a fascinating photocatalyst for solar energy utilization in photo-catalysis.Nevertheless,it often suffers from moderate photo-catalytic activity due to its low specific surfac...Graphitic carbon nitride(g-C_(3)N_(4)) is a fascinating photocatalyst for solar energy utilization in photo-catalysis.Nevertheless,it often suffers from moderate photo-catalytic activity due to its low specific surface area and fast recombination rate of photogenerated electrons upon photo-excitation.Herein,we overcome the bottlenecks by constructing a porous g-C_(3)N_(4) nanosheet(PCNS)through a simple thermal oxidation etching method.Benefited from its porous layer structure,the obtained PCNS exhibits large specific surface area,efficient separation of photogenerated charge carriers,as well as high exposure of active sites.As a result,it is robust and universal in visible light-driven dehydrogenation of alcohols in water under oxidant-free condition.Almost quantitative yields(>99%)of various valuable carbonyl compounds were obtained over PCNS,while bulk g-C_(3)N_(4) was far less efficient.Moreover,the photo-catalyst was highly stable and could be facilely recovered from the aqueous system for efficient reuse.The easy preparation and excellent performance made PCNS a promising and competitive photocatalyst for the solar applications.展开更多
Sulfonic acid functionalized titanate nanotubes were prepared by the sulphonation reaction of hydrothermally synthesized TiO_(2) nanotubes(TNTs) using chlorosulfonic acid as the sulfating agent.The as-prepared catalys...Sulfonic acid functionalized titanate nanotubes were prepared by the sulphonation reaction of hydrothermally synthesized TiO_(2) nanotubes(TNTs) using chlorosulfonic acid as the sulfating agent.The as-prepared catalysts were characterized by fourier transform infrared(FT-IR)spectroscopy,transmission electron microscopy(TEM),scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDX),Xray diffraction(XRD) analysis,thermogravimetry-differential thermal gravimetry(TG-DTG) and X-ray photoelectron spectroscopy(XPS)techniques.The characterization results revealed that the catalysts retained the tubular structure of the TNTs and possessed a large number of active sulfonic acid sites.The catalytic performance of the catalysts for the synthesis of n-butyl levulinate was investigated via the alcoholysis of biomass-derived furfuryl alcohol under atmospheric pressure.The effects of the reaction factors such as the catalyst dosage,reaction time,and temperature on the alcoholysis of the furfuryl alcohol were systematically studied.Under mild conditions,about 79.9% yield of n-butyl levulinate was achieved.In addition,the catalysts showed a stable catalytic performance after four consecutive cycles.Furthermore,no leaching of the active species was observed during the hot filtration testing,which can be attributed to the covalently linked –SO_(3)H groups on the TNTs surface.In addition,the opened tubular nanostructure of the catalyst and the introduced strong Br?nsted acid sites exhibited synergistic effects,which facilitated the selective conversion of the furfuryl alcohol to butyl levulinate.展开更多
A convenient synthesis of oxazolidinone antibacterial linezolid from readily available L-ascorbic acid is described. The key steps include reductive amination of arylamine and (S)-glyceraldehyde acetonide in the pre...A convenient synthesis of oxazolidinone antibacterial linezolid from readily available L-ascorbic acid is described. The key steps include reductive amination of arylamine and (S)-glyceraldehyde acetonide in the presence of NaBH4 and 4A sieve, followed by hydrolysis and regioselective cyclization.展开更多
A mild and simple process for the effective oxidation of 5-hydroxymethylfurfural(HMF) into 2,5-diformylfuran(DFF) has been developed using Na NO2 as the oxidant. Some important reaction parameters were investigate...A mild and simple process for the effective oxidation of 5-hydroxymethylfurfural(HMF) into 2,5-diformylfuran(DFF) has been developed using Na NO2 as the oxidant. Some important reaction parameters were investigated to optimize the oxidation of HMF into DFF. It was found that the reaction solvent was very crucial for this reaction. Trifluoroacetic acid was the best solvent for the oxidation of HMF into DFF by Na NO2.Under the optimal reaction condition, almost quantitative HMF conversion and high DFF yield of 90.4% were obtained after 1 h at room temperature.展开更多
17 MO·(8- x-y )La_2O_3·75B_2O_3· x Eu_2O_3· y Gd_2O_3 (MLBEG,M=Mg,Ca,Sr,Ba) glasses were prepared with the conventional high temperature process. The results of luminescent spectra and ESR reveal t...17 MO·(8- x-y )La_2O_3·75B_2O_3· x Eu_2O_3· y Gd_2O_3 (MLBEG,M=Mg,Ca,Sr,Ba) glasses were prepared with the conventional high temperature process. The results of luminescent spectra and ESR reveal that there are two valence states for europium ions: Eu (2+) and Eu (3+) in this system. The broad emission band peaking at 430 nm corresponds to the 5d→4f emission transition of Eu (2+) ions,and the sharp emission bands peaking at 592,616,650 and 750 nm correspond to the (() 5D_0)→(() 7F_ J) (J =1,2,3,4) emission transition of Eu (3+) ions respectively. In these boron glass networks,the kind of alkaline earth ions determines the amount of Eu (2+) ions reduced from Eu (3+) ions in air. So,the relative emission intensity of blue light and red light of the glass should be controlled by different alkaline earth ions. The experimental results illustrate that the introduction of Gd (3+) ion can distinctly improve the emission intensity ratios between the blue light and red light of the glass,which indicates that the main process of energy transfer is Gd (3+)→Eu (2+)→Eu (3+) in MLBEG system.展开更多
The sequential oxidation-Horner-Wadsworth-Emmons reaction of alcohols to prepare α-Halo-α,β-unsaturated esters (halo =F, Cl) with middle to excellent (Z)-selectivity was developed.
InCl34H2O catalyzes the cross-aldol condensation of cycloalkanones with aromatic aldehydes in sealed tube under solvent free condition to afford an efficient method for the synthesis of a, a-bis(substituted)benzyliden...InCl34H2O catalyzes the cross-aldol condensation of cycloalkanones with aromatic aldehydes in sealed tube under solvent free condition to afford an efficient method for the synthesis of a, a-bis(substituted)benzylidenecycloalkanones.展开更多
基金supported by the National Natural Science Foundation of China (32172972,U19A2040)Science and Technology Innovation Program of Hunan Province (2021RC4028)+4 种基金Earmarked Fund for China Agriculture Research System (CARS-45)Hunan Provincial Science and Technology Department (2019RS5001)Special Funds for Construction of Innovative Provinces in Hunan Province (2021NK1010)Special Science Found of Nansha-South China Agricultural University Fishery Research Institute,Guangzhou (NSYYKY202305,NSYYKY202306)Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province。
文摘The autotetraploid Carassius auratus(4nRR,4n=200,RRRR)is derived from whole-genome duplication of Carassius auratus red var.(RCC,2n=100,RR).In the current study,we demonstrated that chromatophores and pigment changes directly caused the coloration and variation of 4nRR skin(red in RCC,brownish-yellow in4nRR).To further explore the molecular mechanisms underlying coloration formation and variation in 4nRR,we performed transcriptome profiling and molecular functional verification in RCC and 4nRR.Results revealed that scarb1,associated with carotenoid metabolism,underwent significant down-regulation in 4nRR.Efficient editing of this candidate pigment gene provided clear evidence of its significant role in RCC coloration.Subsequently,we identified four divergent scarb1 homeologs in 4nRR:two original scarb1 homeologs from RCC and two duplicated ones.Notably,three of these homeologs possessed two highly conserved alleles,exhibiting biased and allelespecific expression in the skin.Remarkably,after precise editing of both the original and duplicated scarb1homeologs and/or alleles,4nRR individuals,whether singly or multiply mutated,displayed a transition from brownishyellow skin to a cyan-gray phenotype.Concurrently,the proportional areas of the cyan-gray regions displayed a gene-dose correlation.These findings illustrate the subfunctionalization of duplicated scarb1,with all scarb1genes synergistically and equally contributing to the pigmentation of 4nRR.This is the first report concerning the functional differentiation of duplicated homeologs in an autopolyploidfish,substantiallyenrichingour understanding of coloration formation and change within this group of organisms.
文摘The SRI analysis tool was used to comprehensively analyze the seven sets of chemistry questions in the 2021 college entrance examination paper from multiple dimensions such as exploratory test questions,various inquiry standards and exploratory levels.The study found that all test papers involve the examination of scientific inquiry literacy;from the perspective of examination objectives,the 2021 college entrance examination questions as a whole focus on the examination of a single inquiry objective;the questions of each examination paper mainly examine three standards:design scheme,evidence processing and obtaining.The conclusion is drawn;the exploratory level of the chemistry questions in several sets of test papers is mostly a high level.
文摘N decyl 1, 3 diaminopropanes (DNs) were synthesized from alkyl amine acrylonitrile at ambient pressure. With the synthesized DNs as collectors, the flotation of kaolinite, pyrophyllite and illite was conducted and the results were interpreted in terms of the structure activity relationship. The DNs are found to be more effective collectors than dodecyl amine, exhibiting the highest recovery over a pH range of 46. Among the DNs examined, DN 12 shows the highest flotation efficiency. The flotation mechanisms were explained in view of the structures of reagents and aluminium silicate minerals. It is demonstrated that DNs can become new selective collectors for reverse floatation to remove aluminium silicate minerals from bauxite.
文摘Nanophosphor with the nominal composition of Ca0.8 Zn0.2 TiO3 : Pr3 + , Na^+ (CZTOPN) was synthesized at relatively low temperature by the sol-gel method. Metal ions were dispersed by citric acid in ethylene glycol solvent and then react with Ti(OC4H9)4 to form sol and gel. The decomposition process of the precursor, and crystallization and particle size of CZTOPN were examined by thermal analysis (TG-DSC), powder X-ray diffraction (XRD), and scan election microscopy (SEM). Results of TG-DSC and XRD reveal that the composition of Ca0.8 Zn0.2 TiO3 : Pr3 + , Na^+ changes with the sintering temperature. SEM data indicate that the diameter of particles is under 50 nm even if the sintering temperature increases to 1000 ℃. In contrast to a solid state reaction, the excitation spectra of samples synthesized by the sol-gel method shift blue about 10 nm and the emission intensity at 617 nm increases significantly.
基金supported by the Scientific Research Fund of Hunan Provincial Education Department(15C0818,17C0948)the Opening Fund of Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research(Ministry of Education of China)Hunan Normal University(KLCBTCMR201808)
文摘Two single and double chain manganese coordination polymers {[Mn(L1)(H_2O)_2]NO_3}_n(1) and [Mn(L2)_2(H_2O)]_n(2)(HL1 = 2,2?:6?,2??-terpyridine-4?-carboxylic acid, HL2 = 4?-(4-carboxyphenyl)-2,2?:6?,2??-terpyridine) have been synthesized hydrothermally, and characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Compound 1 crystallizes in monoclinic space group P2/c, while 2 crystallizes in triclinic, space group P1. Crystal data for 1: C_(16)H_(14)MnN_4O_7, Mr = 429.25, a = 10.684(2), b = 9.338(1), c = 9.896(2) ?, β = 113.89(3)o, V = 902.7(3) ?~3, Z = 2, T = 153(2) K, Dc = 1.579 g/cm^3, μ = 0.780 mm-1, F(000) = 438, R = 0.1084, wR = 0.3507, and GOF = 1.069; For 2: C44 H30 MnN6 O5, Mr = 777.68, a = 11.255(2), b = 11.554(2), c = 15.417(3) ?, α = 107.28(3), β = 101.07(3), γ = 107.23(3)o, V = 1740.2(6) ?~3, Z = 2, T = 293(2) K, Dc = 1.484 g/cm3, μ = 0.440 mm^(-1), F(000) = 802, R = 0.0471, wR = 0.1050, and GOF = 0.948. In both compounds, the central Mn(Ⅱ) ions adopt the same distorted pentagonal-bipyramid geometry [MnN_3O_4] with different secondary structure units. L1 ligand adopts the μ_2-1κ~3N,N?,N??:2κ~2O,O? mode to coordinate with mononuclear manganese to build a single chainlike compound 1, while L2 employs μ_3-1κ~3N,N?,N??:2κ~2O,O?:3κ~1O and 1κ~1O modes to link dimeric Mn_2O_2 to exhibit a double chainlike 2. Both compounds display weak antiferromagnetic coupling interactions.
基金supported by the Scientific Research Fund of Hunan Provincial Education Department(No.15C0818)
文摘Two new lanthanide coordination polymers, namely [Ln2(μ3-OH)(pydca)-(pyba)3(H2O)]n(Ln = Pr, 1; Eu, 2; Hpyba = 4-(4-pyridyl)benzoic acid; H2 pydca = 2,6-pyridinedicarboxylic acid), have been hydrothermally synthesized and characterized by IR spectroscopy and X-ray single-crystal diffraction. The chains of 1 and 2 are constructed by tetrametallic units of [Ln4(OH)2(pyba)2], which are further linked by μ4-k1N, k1O, k2O′, k2O″-pydca and μ2-k1N, k1O, k1O′-pyba to form 2D frameworks. Luminescence measurement reveals that compound 2 exhibits strong reddish emission at room temperature.
基金supported by the National Natural Science Foundation of China(12205300 and 12135012)the Natural Science Foundation of Anhui Province(2208085QA28 and 2208085J01)。
文摘Simultaneously realizing improved activity and stability of acidic oxygen evolution reaction(OER) electrocatalysts is highly promising for developing cost-effective sustainable energy in the splitting of water technique.Herein,we report iridium nanocrystals embedded into 3D conductive clothes(Ir-NCT/CC) as a low iridium electrocatalyst realizing ultrahigh acidic OER activity and robust stability.The well-designed Ir-NCT/CC requires a low overpotential of 202 mV to reach the current density of 10 mA cm^(-2)with a high mass activity of 1754 A g^(-1).Importantly,in acidic overall water splitting,Ir-NCT/CC merely delivers a cell voltage of 1.469 V at a typical current density of 10 mA cm^(-2)and also maintains robust durability under continuous operation.We identify that a low working voltage drives the formation of a highly stable amorphous IrOxactive phase over the surface of Ir nanocrystals(surface heterojunction IrOx/Ir-NCT) during operating conditions,which contributes to an effective and durable OER process.
基金Projects(30571779,10775085) supported by the National Natural Science Foundation of ChinaProject(Z07000200540704) supported by Beijing Municipal Science and Technology Commission,China
文摘Fe3O4 magnetic nanoparticles with diameters varying from 10 to 426 nm were synthesized and characterized.Heating effects of Fe3O4 magnetic nanoparticles under radiofrequency capacitive field(RCF) with frequency of 27.12 MHz and power of 60-150 W were investigated.When the power of RCF is lower than 90 W,temperatures of Fe3O4 magnetic nanoparticles(75-150 mg/mL) can be raised and maximal temperatures are all lower than 50 ℃.When the power of RCF is 90-150 W,temperatures of Fe3O4 magnetic nanoparticles can be quickly raised and are all obviously higher than those of normal saline and distilled water under the same conditions.Temperature of Fe3O4 magnetic nanoparticles can even reach 70.2 ℃ under 150 W RCF.Heating effects of Fe3O4 magnetic nanoparticles are related to RCF power,particle size and particle concentration.
基金This work was supported by the National Natural Science Foundation of China(20275010,20335020)the Basic Research Special Program of the Ministry of Science and Technology of China(2003CCC00700)the Foundation of the Ministry of Education(M0E)of China(jiaorensi[2000]26,jiaojisi[2000]65).
文摘The quartz crystal microbalance (QCM) was used to monitor the one-day incubation of human breast cancer cells (MCF-7) on the gold electrode. In combination with an optical microscope simulation experiment, the cell-population pictures at various stages, the QCM responses to the cells' adhesion, spreading and proliferation on the electrode surface were discussed. The △f0 and △R1 responses were found mainly from mixed effects of viscodensity and surface stress, and in proportion to the cell coverage, rather than to the number of cells at the electrode. The significant fore-and-aft changes in cyclic voltammetry and electrochemical impedance spectroscopy of the ferri-ferrocyanide redox couple also proved that the cells were adhesion to the gold surface.
基金supported by the National Natural Science Foundation of China(No.20474015)the Scientific Research Fund of Hunan Provincial Education Department(No.04A029).
文摘A hydrophilic/hydrophobic interpenetrating polymer network (IPN) of poly (vinyl alcohol) / polystyrene was prepared by conversion of the IPN of poly (vinyl acetate)/polystyrene. The hydrophilic/hydrophobic IPN was characterized by FT-IR and DSC, and the swelling ratios of the IPN in different solvents were measured.
文摘A new electrochemical oscillatory system of bromate in alkaline solution is reported.In Pt-Bromate-Alkaline solution system,two different types of electrochemical oscillations(Type Ⅰ and Type Ⅱ) can be observed.Type Ⅰ appears before hydrogen evolution and Type Ⅱ involves periodic hydrogen evolution.Type Ⅰ relates to the adsorption/desorption of the hydrogen on platinum electrode,and Type Ⅱ with periodic oscillation stems from the coupling of electrochemical reactions(the reduction of bromate and evolution hydrogen reaction) with mass transfer(diffusion and convection).More over,under the right conditions,the two types appear in different oscillatory modes,for example,simple periodical mode and mixed one,etc..Crossed cycle in the cyclic voltammograms,which is the basic characteristics for electrochemical oscillatory systems,has also been observed as expected.
文摘The luminescent properties of glasses synthesized in air atmosphere by conventional high temperature process were studied. The emissions spectra of Eu2+ and Eu3+ were observed in BaO-La2O3-B2O3-Eu2O3 glasses. The results show that the broad emission peaks at 430 nm correspond to 5d→4f emission transition of Eu2+, the sharp emission peaks at 592, 616, 650 and 750 nm correspond to 5D0→7Fj(j=1-4) emission transition of Eu3+, respectively, which indicates that the BaO-La2O3-B2O3-Eu2O3 glass can convert ultraviolet and green components of sunlight into blue and red light so as to increase the intensity of blue and red light, respectively. The luminescent intensity of Eu2+ increases with increasing the molar ratio of Tb3+ in BaO-La2O3-B2O3-Eu2O3-Tb4O7 glasses, whereas the luminescent intensity of Eu3+ decreases. So the luminescent intensity of Eu(III, II) is influenced by Tb3+. These phenomena can be explained by electron transfer mechanism: Eu3+(4f6)+Tb3+(4f8)→Eu2+(4f7)+Tb4+(4f7). Taking advantage of the luminescent properties of BaO-La2O3-B2O3-Eu2O3 glasses, light-conversion glass for agriculture can be produced.
基金financial support provided by the National Natural Science Foundation of China(21676078)the Natural Science Foundation of Hunan Province for Distinguished Young Scholar(2016JJ1013)+1 种基金Scientific Research Fund of Hunan Provincial Education Department(19A323)Science and Technology Planning Project of Hunan Province(2018TP1017)。
文摘Graphitic carbon nitride(g-C_(3)N_(4)) is a fascinating photocatalyst for solar energy utilization in photo-catalysis.Nevertheless,it often suffers from moderate photo-catalytic activity due to its low specific surface area and fast recombination rate of photogenerated electrons upon photo-excitation.Herein,we overcome the bottlenecks by constructing a porous g-C_(3)N_(4) nanosheet(PCNS)through a simple thermal oxidation etching method.Benefited from its porous layer structure,the obtained PCNS exhibits large specific surface area,efficient separation of photogenerated charge carriers,as well as high exposure of active sites.As a result,it is robust and universal in visible light-driven dehydrogenation of alcohols in water under oxidant-free condition.Almost quantitative yields(>99%)of various valuable carbonyl compounds were obtained over PCNS,while bulk g-C_(3)N_(4) was far less efficient.Moreover,the photo-catalyst was highly stable and could be facilely recovered from the aqueous system for efficient reuse.The easy preparation and excellent performance made PCNS a promising and competitive photocatalyst for the solar applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.21606082,21776068)the Hunan Provincial Natural Science Foundation of China(Grant No.2018JJ3334)+1 种基金the Key Scientific Research Fund of Hunan Provincial Education Department(Grant No.19A035)the Collaborative Innovation Center of New Chemical Technologies for Environmental Benignity and Efficient Resource Utilization。
文摘Sulfonic acid functionalized titanate nanotubes were prepared by the sulphonation reaction of hydrothermally synthesized TiO_(2) nanotubes(TNTs) using chlorosulfonic acid as the sulfating agent.The as-prepared catalysts were characterized by fourier transform infrared(FT-IR)spectroscopy,transmission electron microscopy(TEM),scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDX),Xray diffraction(XRD) analysis,thermogravimetry-differential thermal gravimetry(TG-DTG) and X-ray photoelectron spectroscopy(XPS)techniques.The characterization results revealed that the catalysts retained the tubular structure of the TNTs and possessed a large number of active sulfonic acid sites.The catalytic performance of the catalysts for the synthesis of n-butyl levulinate was investigated via the alcoholysis of biomass-derived furfuryl alcohol under atmospheric pressure.The effects of the reaction factors such as the catalyst dosage,reaction time,and temperature on the alcoholysis of the furfuryl alcohol were systematically studied.Under mild conditions,about 79.9% yield of n-butyl levulinate was achieved.In addition,the catalysts showed a stable catalytic performance after four consecutive cycles.Furthermore,no leaching of the active species was observed during the hot filtration testing,which can be attributed to the covalently linked –SO_(3)H groups on the TNTs surface.In addition,the opened tubular nanostructure of the catalyst and the introduced strong Br?nsted acid sites exhibited synergistic effects,which facilitated the selective conversion of the furfuryl alcohol to butyl levulinate.
文摘A convenient synthesis of oxazolidinone antibacterial linezolid from readily available L-ascorbic acid is described. The key steps include reductive amination of arylamine and (S)-glyceraldehyde acetonide in the presence of NaBH4 and 4A sieve, followed by hydrolysis and regioselective cyclization.
基金supported by the National Natural Science Foundation of China(21272065)Scientific Research Fund of Hunan Provincial Education Department(13C562+2 种基金15C0816)Outstanding Youth Project of Hunan Provincial Education Department(15B134)the funding offered by China Scholarship Council(201506720018)
文摘A mild and simple process for the effective oxidation of 5-hydroxymethylfurfural(HMF) into 2,5-diformylfuran(DFF) has been developed using Na NO2 as the oxidant. Some important reaction parameters were investigated to optimize the oxidation of HMF into DFF. It was found that the reaction solvent was very crucial for this reaction. Trifluoroacetic acid was the best solvent for the oxidation of HMF into DFF by Na NO2.Under the optimal reaction condition, almost quantitative HMF conversion and high DFF yield of 90.4% were obtained after 1 h at room temperature.
文摘17 MO·(8- x-y )La_2O_3·75B_2O_3· x Eu_2O_3· y Gd_2O_3 (MLBEG,M=Mg,Ca,Sr,Ba) glasses were prepared with the conventional high temperature process. The results of luminescent spectra and ESR reveal that there are two valence states for europium ions: Eu (2+) and Eu (3+) in this system. The broad emission band peaking at 430 nm corresponds to the 5d→4f emission transition of Eu (2+) ions,and the sharp emission bands peaking at 592,616,650 and 750 nm correspond to the (() 5D_0)→(() 7F_ J) (J =1,2,3,4) emission transition of Eu (3+) ions respectively. In these boron glass networks,the kind of alkaline earth ions determines the amount of Eu (2+) ions reduced from Eu (3+) ions in air. So,the relative emission intensity of blue light and red light of the glass should be controlled by different alkaline earth ions. The experimental results illustrate that the introduction of Gd (3+) ion can distinctly improve the emission intensity ratios between the blue light and red light of the glass,which indicates that the main process of energy transfer is Gd (3+)→Eu (2+)→Eu (3+) in MLBEG system.
文摘The sequential oxidation-Horner-Wadsworth-Emmons reaction of alcohols to prepare α-Halo-α,β-unsaturated esters (halo =F, Cl) with middle to excellent (Z)-selectivity was developed.
文摘InCl34H2O catalyzes the cross-aldol condensation of cycloalkanones with aromatic aldehydes in sealed tube under solvent free condition to afford an efficient method for the synthesis of a, a-bis(substituted)benzylidenecycloalkanones.