In this work, a series of coal-based active carbon （CAC） catalysts loaded by A1203 were prepared by sol-gel method and used for the simulta- neous catalytic hydrolysis of carbonyl sulfide （COS） and carbon disulfi...In this work, a series of coal-based active carbon （CAC） catalysts loaded by A1203 were prepared by sol-gel method and used for the simulta- neous catalytic hydrolysis of carbonyl sulfide （COS） and carbon disulfide （CS2） at relatively low temperatures of 30-70 ℃. The influences of calcinations temperatures and operation conditions such as： reaction temperature, 02 concentration, gas hourly space velocity （GHSV） and relative humidity （RH） were also discussed respectively. The results showed that catalysts with 5.0 wt% A1203 calcined at 300 ℃ had supe- rior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50 ℃, catalytic hydrolysis activity of COS could be enhanced but that of CS2 was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2 decrease. A small amount of 02 introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2.展开更多
The sol–gel method was used to synthesize a series of metal oxides-supported activated carbon fiber (ACF) and the simultaneous catalytic hydrolysis activity of carbonyl sulfide (COS)and carbon disulfide (CS2) at rela...The sol–gel method was used to synthesize a series of metal oxides-supported activated carbon fiber (ACF) and the simultaneous catalytic hydrolysis activity of carbonyl sulfide (COS)and carbon disulfide (CS2) at relatively low temperatures of 60°C was tested.The effects of preparation conditions on the catalyst properties were investigated,including the kinds and amount of metal oxides and calcination temperatures.The activity tests indicated that catalysts with 5 wt.%Ni after calcining at 400°C (Ni(5)/ACF(400)) had the best performance for the simultaneous catalytic hydrolysis of COS and CS2.The surface and structure properties of prepared ACF were characterized by scanning electron microscope-energy disperse spectroscopy (SEM-EDS),Brunauer–Emmett–Teller (BET),X-ray diffraction (XRD),carbon dioxidetemperature programmed desorption (CO2-TPD) and diffuse reflectance Fourier transform infrared reflection (DRFTIR).And the metal cation defects were researched by electron paramagnetic resonance (EPR) method.The characterization results showed that the supporting of Ni on the ACF made the ACF catalyst show alkaline and increased the specific surface area and the number of micropores,then improved catalytic hydrolysis activity.The DRFTIR results revealed that-OH species could facilitate the hydrolysis of COS and CS2;-COO and-C–O species could facilitate the oxidation of catalytic hydrolysate H2S.And the EPR results showed that high calcination temperature conditions provide more active reaction center for the COS and CS2 adsorption.展开更多
β-Keto-δ-valerolactones, which were obtained by reaction of acetoacetate with aldehydes or ketones, reacted with carbon disulfide, alkyl halides and a new condensation reaction was developed. The structures of the p...β-Keto-δ-valerolactones, which were obtained by reaction of acetoacetate with aldehydes or ketones, reacted with carbon disulfide, alkyl halides and a new condensation reaction was developed. The structures of the products 3 were confirmed by HNMR spectra and elemental 1 analysis.展开更多
The relationship between carbon disulfide (CS2) and the symptoms and signs of nervous system in rayon workers was investigated. In a cross sectional study of CS2-exposed workers from the viscose industry and controls,...The relationship between carbon disulfide (CS2) and the symptoms and signs of nervous system in rayon workers was investigated. In a cross sectional study of CS2-exposed workers from the viscose industry and controls, data on neurological symptoms and clinical neurological examination were evaluated. Theexposed subjects includes 326 workers and 105 workers from the same factory,without exposure to CS2 or to any other neurotoxic agents, served as controls.The median exposure to CS2(8 h time weighted) in the low-level exposure group was 4. 6 mg/m3, and 18. 3 mg/m3 in high-level exposure group. Non-conditional multiple logistic regression analysis was employed for evaluating statistical differ-ences by using SAS software. In the analysis, age, sex, work time, body massindex (BMI), smoking and drinking habits, educational background and marriage status were controlled. The odds ratio (OR) significantly increased of some symptoms in workers exposed to CS2 at levels below 10 mg/m3, as compared to con-trols. The dose-effect relationship between the exposure to CS2 and the symptoms of nervous system was demonstrated. In terms of neurological parameters, no other abnorrnal change but that in temperature sensitivity was observed in work-ers exposed to CS2. In conclusion, the influence of low level CS2 on nervous system of workers should not be ignored.展开更多
In this letter ab initio electronic structure calculations are performed for extensive geometries Of CS2. A newly written program is used to fit the computed energies into the Sorbie-Murrel function, whose contour plo...In this letter ab initio electronic structure calculations are performed for extensive geometries Of CS2. A newly written program is used to fit the computed energies into the Sorbie-Murrel function, whose contour plots are illustrated.展开更多
Photochemical production of carbonyl sulfide（COS）,carbon disulfide（CS_2） and dimethyl sulfide（DMS） was intensively studied in the water from the Aohai Lake of Beijing city.The lake water was found to be highly s...Photochemical production of carbonyl sulfide（COS）,carbon disulfide（CS_2） and dimethyl sulfide（DMS） was intensively studied in the water from the Aohai Lake of Beijing city.The lake water was found to be highly supersaturated with COS,CS_2 and DMS,with their initial concentrations of 0.91 ± 0.073 nmol/L,0.55 ± 0.071 nmol/L and 0.37 ± 0.062 nmol/L,respectively.The evident photochemical production of COS and CS_2 in the lake water under irradiation of 365 nm and 302 nm indicated that photochemical production of them might be the reason for their supersaturation.The similar dependence of wavelength and oxygen for photochemical production of COS,CS_2 and DMS implied that they might be from the same precursors.The water cage effect was found to favor COS production but inhibit CS_2and DMS formation,indicating that COS photochemical production was mainly from direct degradation of the precursors and the formation of CS_2 and DMS needed intermediates via combination of carbon-centered radicals and sulfur-centered radicals.The above assumptions were further confirmed by simulation experiments with addition of carbonyls and amino acids（cysteine and methionine）,and the photochemical formation mechanisms for COS,CS_2 and DMS in water were derived from the investigations.展开更多
Moringa plant belongs to the family Moringaceae within the order Brassicales. It is a magical plant which contains 7 timesthe vitamin C content of oranges,4 times the vitamin A content of carrots, 4 times the calcium ...Moringa plant belongs to the family Moringaceae within the order Brassicales. It is a magical plant which contains 7 timesthe vitamin C content of oranges,4 times the vitamin A content of carrots, 4 times the calcium content of milk ,3 times the potassiumcontent of bananas and 2 times the protein content of yogurt (gram to gram) . The most widely distributed species is Moringa oleiferaLam., referred as drumstick tree for the shape of its seed pods. Leaves of M. oleifera are rich in a unique glucosinolate namedglucomoringin. Moringa were found to release CS2 when submitted to experimental conditions of dithiocarbamate residue analysis.Gas chromatography was used to quantitate CS2 and control samples were obtained from Moringa plantations cultivated inexperimental areas, in which no treatment with fungicides of the dithiocarbamate group was applied. Endogenous CS2 levels werecompared with dithiocarbamate residues measured in Moringa samples from the field trials following applications of the macozeebfungicide. Use small leaves resulted in an observed decrease in CS2 concentration comparable to the large leaves. Temperature levelused has an effect on the concentration of CS2 measured as an indicator for dithiocarbamate pesticide residue. And use of hightemperature (100 °C) in drying of Moringa leaves after harvesting may lead to some biochemical changes that caused an observedincrease in CS2 concentration comparable to drying at (50 °C). Evidence for formation of dithiocarbamate compound from moringinin moringa leaves are metabolized/detoxified principally by the mercapturic acid pathway. Conjugation with glutathione (GSH)promoted by glutathione transferases gives rise to the corresponding Glucosinolate -. Isothiocyanate conjugates. These undergofurther enzymatic modifications to give rise sequentially to the cysteinylglycine cysteine - Isothiocyanate andN-acetylcysteine-Isothiocyanate conjugates, all of which are dithiocarbamates. The detection of an ion with a m/z value 430.40, withthe following fragments m/z 165.10 and m/z 121.05 respectively, among the ions analyzed by GC-MS gives a clear evidence forformation of dithiocarbamate by addition of glutathione to the isothiocyanate formed from glucosinolate in moringa plant.展开更多
The installation of a trifluoromethyl group onto a nitrogen atom can effectively modulate the basicity of amines owing to the strong electron-withdrawing effect of fluorine.Nevertheless,efficient and opera-tionally si...The installation of a trifluoromethyl group onto a nitrogen atom can effectively modulate the basicity of amines owing to the strong electron-withdrawing effect of fluorine.Nevertheless,efficient and opera-tionally simple methods for N-trifluoromethylation of amines are yet to be developed.This protocol involves the use of readily available secondary amines as starting materials,along with CS 2 and AgF as the N-trifluoromethylation reagents,enabling the target molecules to be synthesized in a single step.The versatility of our method was demonstrated by successfully synthesizing N,N-dialkyl and N-(hetero)aromatic N-CF_(3)-containing compounds with various substituents.Moreover,this methodology has been successfully applied to the late-stage modification of complex bioactive molecules,facilitating the synthe-sis of N-CF_(3) drug bioisosteres and N-CF_(3)-tailored amino acids,which would broadly stimulate the drug discovery of N-CF_(3) containing molecules.展开更多
Background Carbon disulfide （CS2） is a commonly used organic solvent. Many epidemiological investigations and animal experiments have indicated that learning and memory ability can be affected to different degrees a...Background Carbon disulfide （CS2） is a commonly used organic solvent. Many epidemiological investigations and animal experiments have indicated that learning and memory ability can be affected to different degrees after long-term exposure to CS2, but the mechanisms are still unclear. The aim of this study was to explore the possible mechanisms of CS2-related impairment of the learning and memory ability of rats, by investigating the effects of CS2 on nitric oxide synthase （NOS） activity and NOS mRNA expression in rat hippocampus. Methods Rat models of toxicity were generated by inhalation of various doses of CS2. After two months of inhaling intoxication, the activities of constitutive NOS （cNOS） and induced NOS （iNOS） in the hippocampus were measured. The levels of neuronal NOS （nNOS） mRNA and iNOS mRNA were measured by semi-quantitative reverse transcription polymerase chain reaction （RT-PCR）. Results cNOS activity was significantly decreased compared with controls, while iNOS activity was changed only slightly. CS2 treatment significantly decreased nNOS mRNA levels, iNOS mRNA levels were significantly increased only at higher doses of CS2. Conclusion The effect of CS2 on learning and memory ability in rats is related to the activity of NOS and the expression of nNOS in the hippocampus.展开更多
Supported coupling catalysts for CS2 removal were prepared with different activated carbons originated from wood,coconut shell and coal as supports,and their catalytic activities for CS2 removal were tested at ambient...Supported coupling catalysts for CS2 removal were prepared with different activated carbons originated from wood,coconut shell and coal as supports,and their catalytic activities for CS2 removal were tested at ambient temperature.The textural and surface properties of the activated carbons were characterized by nitrogen adsorption,temperature-programmed desorption（TPD）and Boehm titration.The activated carbon support with meso-and macropores,and oxygen-functional groups performs higher CS2 removal ability at ambient temperature.The effects of flow rate,CS2 inlet concentration,temperature and relative humidity on CS2 removal were also investigated.High efficient removal is obtained at temperature of 50-C,space velocity of 2000 h-1,inlet CS2 concentration of 500 mgS/m3 and relative humidity of 20%with the breakthrough sulfur capacity up to 4.3 gS/gCat and working sulfur capacity up to 7 gS/gCat.展开更多
Herein, a facile synthesis of valuable pyrido[1,2-a]pyrimidine-4-thiones is reported via novel thiocarbonylation of C(sp^(3))-H bonds with carbon disulfide(CS_(2)). This reaction features easy availability of substrat...Herein, a facile synthesis of valuable pyrido[1,2-a]pyrimidine-4-thiones is reported via novel thiocarbonylation of C(sp^(3))-H bonds with carbon disulfide(CS_(2)). This reaction features easy availability of substrates,good functional group tolerance, high yields, facile scalability and atom economy. Mechanistic investigations indicate that sulfate anion and sulfuric anhydride anion might be involved in this reaction.展开更多
Replacing platinum for catalyzing hydrogen evolution reaction （HER） in acidic medium remains great chal- lenges. Herein, we prepared few-layered MoS2 by ball milling as an efficient catalyst for HER in acidic medium...Replacing platinum for catalyzing hydrogen evolution reaction （HER） in acidic medium remains great chal- lenges. Herein, we prepared few-layered MoS2 by ball milling as an efficient catalyst for HER in acidic medium, The activity of as-prepared MoS2 had a strong dependence on the ball milling time, Furthermore, Ketjen Black EC 300J was added into the ball-milled MoS2 followed by a second ball milling, and the resultant MoS2/carbon black hybrid material showed a much higher HER activity than MoS2 and carbon black alone. The enhanced activity of the MoS2/carbon black hybrid material was attributed to the increased abundance of catalytic edge sites of MoS） and excellent electrical coupling to the underlving carbon network.展开更多
MoS_2 nanosheet arrays supported on hierarchical nitrogen-doped porous carbon（MoS_2@C） have been synthesized by a facile hydrothermal approach combined with high-temperature calcination.The hierarchical nitrogen-dop...MoS_2 nanosheet arrays supported on hierarchical nitrogen-doped porous carbon（MoS_2@C） have been synthesized by a facile hydrothermal approach combined with high-temperature calcination.The hierarchical nitrogen-doped porous carbon can serve as three-dimensional conductive frameworks to improve the electronic transport of semiconducting MoS_2.When evaluated as anode material for lithium-ion batteries,the MoS_2@C exhibit enhanced electrochemical performances compared with pure MoS_2 nanosheets,including high capacity（1305.5 mAhg^（-1） at lOOmAg^（-1））,excellent rate capability（438.4mAhg^（-1） at 1000mAg^（-1））.The reasons for the improved electrochemical performances are explored in terms of the high electronic conductivity and the facilitation of lithium ion transport arising from the hierarchical structures of MoS_2@C.展开更多
Rare earth sulfides were systematically synthesized via the sulfurization of their commercial oxide powders using CS2 gas to shorten sulfurization time, and their UV-vis absorption spectra were investigated. The appro...Rare earth sulfides were systematically synthesized via the sulfurization of their commercial oxide powders using CS2 gas to shorten sulfurization time, and their UV-vis absorption spectra were investigated. The appropriate sulfurization conditions were studied. For the rare earth sulfides with the same crystal structure, the sulfurization temperature showed increasing tendency with the decrease of rare earth element atomic radii. The UV-vis absorption spectra of rare earth sulfides did not depend on the crystal structure of rare earth sulfides, but on the 4f electronic structure of rare earth element. The data showed that the optical band gaps of rare earth sulfides were irregular, and the values ranged from 1.65 to 3.75 eV.展开更多
Waste hops are good sources of flavonoids. Extraction of flavonoids from waste hops (SC-CO2 extracted hops) using supercritical fluids technology was investigated. Various temperatures, pressures and concentrations of...Waste hops are good sources of flavonoids. Extraction of flavonoids from waste hops (SC-CO2 extracted hops) using supercritical fluids technology was investigated. Various temperatures, pressures and concentrations of ethanol (modifier) and the ratio (w/w) of solvent to material were tested in this study. The results of single factor and orthogonal experiments showed that at 50 °C, 25 MPa, the ratio of solvent to material (50%), ethanol concentration (80%) resulted in maximum extraction yield fla- vonoids (7.8 mg/g). HPLC-MS analysis of the extracts indicated that flavonoids obtained were xanthohumol, the principal prenylflavonoid in hops.展开更多
The formation behaviors of terbium sesquisulfide(Tb_2S_3)and holmium sesquisulfide(Ho_2S_3)synthesized via the sulfurization of their oxide powders using CS_2 gas in the range of temperature 673 to 1323 K were investi...The formation behaviors of terbium sesquisulfide(Tb_2S_3)and holmium sesquisulfide(Ho_2S_3)synthesized via the sulfurization of their oxide powders using CS_2 gas in the range of temperature 673 to 1323 K were investigated. In the sulfurization of Tb_4O_7 powder, Tb_2O_3 and Tb_2O_2S were formed in the initial stage of reaction, and α-Tb_2S_3 was finally formed at higher temperature. For long sulfurization time of 8 h, single-phase α-Tb_2S_3 could be synthesized at 1323 K. In the sulfurization of Ho_2O_3 powder using CS_2 gas, only Ho_2O_2S was formed as an intermediate product. At a sulfurization temperature above 873 K, Ho_2O_2S was formed in the initial stage of reaction, and single-phase δ-Ho_2S_3 was formed at 1323 K for 8 h instead of Ho_2O_2S. Furthermore, the influence of the addition of carbon black to the sulfurization of Ho_2O_3 powder using CS_2 gas was investigated, and the result implied that the reactions were accelerated slightly by the addition of carbon black.展开更多
CS2 removal was obtained by coupling catalytic hyidation on bi-functional catalyst. On the hydrolysis active sites, CS2 is hydrolyzed to HES, while on the oxidation active sites, HES is oxidized to elemental S or sulf...CS2 removal was obtained by coupling catalytic hyidation on bi-functional catalyst. On the hydrolysis active sites, CS2 is hydrolyzed to HES, while on the oxidation active sites, HES is oxidized to elemental S or sulfuric acid deposited on the porous support. The above process can be expressed as follows： CS2 H2O→ COS H2O→ H2S O2→ S/SO4^2-. H2S oxidation eliminates its prohibition on C52 hydrolysis so that the rate of coupling removal CS2 is 5 times higher than that of CS2 hydrolysis. The same active energy of hydrolysis and coupling reaction also indicates that HES oxidation does not change the reaction mechanism of CS2 hydrolysis. Temperature has obvious effect on the process while the mole ratio of O2 concentration to CS2 concentration （O/S） does not, especially in excess of 2.5. The formation of sulfuric acid on the catalyst surface poisons hydrolysis active sites and causes the decrease of left OH^-1 concentration on the catalysts surface. Lower temperature is suggested for this bi-functional catalyst owing to the low yield ratio of S/SO4^2-.展开更多
A series of substituted l,4-oxathiane-3-thione derivatives were synthesized via one-pot multicomponent reactions of nitromethane,carbon disulfide and oxiranes in the presence of Et;N in water as the solvent under micr...A series of substituted l,4-oxathiane-3-thione derivatives were synthesized via one-pot multicomponent reactions of nitromethane,carbon disulfide and oxiranes in the presence of Et;N in water as the solvent under microwave irradiation.Particularly valuable features of this method include high yields of products,broad substrate scope,short reaction time and straightforward procedure.展开更多
In order to investigate the suitability of ternary rare earth sulfide LanCe2 xS3 in plastic application as a red pigment, we prepared LaxCe2 xS3 via the sulfurization of the oxide powders using CS2 gas. In the sulfuri...In order to investigate the suitability of ternary rare earth sulfide LanCe2 xS3 in plastic application as a red pigment, we prepared LaxCe2 xS3 via the sulfurization of the oxide powders using CS2 gas. In the sulfurization of LaxCe2_xS3, β-phase and y-phase ter- nary rare earth sulfide LaxCe2_xS3 were synthesized at the sulfufization temperature of 1000 and 1250 ℃ for 3 h, respectively. The UV-vis absorption spectra of synthesized LaxCe2_xS3 showed that the absorption wavelengths of 13-phase and y-phase LaxCe2_xS3 samies were in the region of 617-70 nm and 607-53 nm, respectively. They were in red absorption region. Furthermore, the scanning electron microscopy （SEM） results of the synthesized LaxCe2-S3 samples were investigated. The typical SEM microgmphs indicated that the particle sizes of synthesized LaxCe2 xS3 were in the range of 0.5-5 μm.展开更多
An efficient synthesis of alkyl bis（dimethylamino）methylenecarbamodithioates via a one-pot reaction between 1,1,3,3- tetramethylguanidine, carbon disulfide and substituted oxiranes, in good yields, is described.
基金supported by the Ministry of Environmental Protection,Public Welfare Project(Contract No 201109034)the National Natural Science Foundation(U1137603)
文摘In this work, a series of coal-based active carbon （CAC） catalysts loaded by A1203 were prepared by sol-gel method and used for the simulta- neous catalytic hydrolysis of carbonyl sulfide （COS） and carbon disulfide （CS2） at relatively low temperatures of 30-70 ℃. The influences of calcinations temperatures and operation conditions such as： reaction temperature, 02 concentration, gas hourly space velocity （GHSV） and relative humidity （RH） were also discussed respectively. The results showed that catalysts with 5.0 wt% A1203 calcined at 300 ℃ had supe- rior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50 ℃, catalytic hydrolysis activity of COS could be enhanced but that of CS2 was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2 decrease. A small amount of 02 introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2.
基金supported by the National Key R&D Program of China (No.2018YFC0213400)the National Natural Science Foundation of China (Nos.51968034,41807373,21667015 and51708266)the Science and Technology Program of Yunnan province (No.2019FB069)。
文摘The sol–gel method was used to synthesize a series of metal oxides-supported activated carbon fiber (ACF) and the simultaneous catalytic hydrolysis activity of carbonyl sulfide (COS)and carbon disulfide (CS2) at relatively low temperatures of 60°C was tested.The effects of preparation conditions on the catalyst properties were investigated,including the kinds and amount of metal oxides and calcination temperatures.The activity tests indicated that catalysts with 5 wt.%Ni after calcining at 400°C (Ni(5)/ACF(400)) had the best performance for the simultaneous catalytic hydrolysis of COS and CS2.The surface and structure properties of prepared ACF were characterized by scanning electron microscope-energy disperse spectroscopy (SEM-EDS),Brunauer–Emmett–Teller (BET),X-ray diffraction (XRD),carbon dioxidetemperature programmed desorption (CO2-TPD) and diffuse reflectance Fourier transform infrared reflection (DRFTIR).And the metal cation defects were researched by electron paramagnetic resonance (EPR) method.The characterization results showed that the supporting of Ni on the ACF made the ACF catalyst show alkaline and increased the specific surface area and the number of micropores,then improved catalytic hydrolysis activity.The DRFTIR results revealed that-OH species could facilitate the hydrolysis of COS and CS2;-COO and-C–O species could facilitate the oxidation of catalytic hydrolysate H2S.And the EPR results showed that high calcination temperature conditions provide more active reaction center for the COS and CS2 adsorption.
文摘β-Keto-δ-valerolactones, which were obtained by reaction of acetoacetate with aldehydes or ketones, reacted with carbon disulfide, alkyl halides and a new condensation reaction was developed. The structures of the products 3 were confirmed by HNMR spectra and elemental 1 analysis.
文摘The relationship between carbon disulfide (CS2) and the symptoms and signs of nervous system in rayon workers was investigated. In a cross sectional study of CS2-exposed workers from the viscose industry and controls, data on neurological symptoms and clinical neurological examination were evaluated. Theexposed subjects includes 326 workers and 105 workers from the same factory,without exposure to CS2 or to any other neurotoxic agents, served as controls.The median exposure to CS2(8 h time weighted) in the low-level exposure group was 4. 6 mg/m3, and 18. 3 mg/m3 in high-level exposure group. Non-conditional multiple logistic regression analysis was employed for evaluating statistical differ-ences by using SAS software. In the analysis, age, sex, work time, body massindex (BMI), smoking and drinking habits, educational background and marriage status were controlled. The odds ratio (OR) significantly increased of some symptoms in workers exposed to CS2 at levels below 10 mg/m3, as compared to con-trols. The dose-effect relationship between the exposure to CS2 and the symptoms of nervous system was demonstrated. In terms of neurological parameters, no other abnorrnal change but that in temperature sensitivity was observed in work-ers exposed to CS2. In conclusion, the influence of low level CS2 on nervous system of workers should not be ignored.
文摘In this letter ab initio electronic structure calculations are performed for extensive geometries Of CS2. A newly written program is used to fit the computed energies into the Sorbie-Murrel function, whose contour plots are illustrated.
基金supported through Strategic Priority Research Program projects(B)of the Chinese Academy of Sciences(No.XDB05010100)the Special Fund for Environmental Research in the Public Interest(No.201509002)the National Natural Science Foundation of China(Nos.21477142,41575121,41203070)
文摘Photochemical production of carbonyl sulfide（COS）,carbon disulfide（CS_2） and dimethyl sulfide（DMS） was intensively studied in the water from the Aohai Lake of Beijing city.The lake water was found to be highly supersaturated with COS,CS_2 and DMS,with their initial concentrations of 0.91 ± 0.073 nmol/L,0.55 ± 0.071 nmol/L and 0.37 ± 0.062 nmol/L,respectively.The evident photochemical production of COS and CS_2 in the lake water under irradiation of 365 nm and 302 nm indicated that photochemical production of them might be the reason for their supersaturation.The similar dependence of wavelength and oxygen for photochemical production of COS,CS_2 and DMS implied that they might be from the same precursors.The water cage effect was found to favor COS production but inhibit CS_2and DMS formation,indicating that COS photochemical production was mainly from direct degradation of the precursors and the formation of CS_2 and DMS needed intermediates via combination of carbon-centered radicals and sulfur-centered radicals.The above assumptions were further confirmed by simulation experiments with addition of carbonyls and amino acids（cysteine and methionine）,and the photochemical formation mechanisms for COS,CS_2 and DMS in water were derived from the investigations.
文摘Moringa plant belongs to the family Moringaceae within the order Brassicales. It is a magical plant which contains 7 timesthe vitamin C content of oranges,4 times the vitamin A content of carrots, 4 times the calcium content of milk ,3 times the potassiumcontent of bananas and 2 times the protein content of yogurt (gram to gram) . The most widely distributed species is Moringa oleiferaLam., referred as drumstick tree for the shape of its seed pods. Leaves of M. oleifera are rich in a unique glucosinolate namedglucomoringin. Moringa were found to release CS2 when submitted to experimental conditions of dithiocarbamate residue analysis.Gas chromatography was used to quantitate CS2 and control samples were obtained from Moringa plantations cultivated inexperimental areas, in which no treatment with fungicides of the dithiocarbamate group was applied. Endogenous CS2 levels werecompared with dithiocarbamate residues measured in Moringa samples from the field trials following applications of the macozeebfungicide. Use small leaves resulted in an observed decrease in CS2 concentration comparable to the large leaves. Temperature levelused has an effect on the concentration of CS2 measured as an indicator for dithiocarbamate pesticide residue. And use of hightemperature (100 °C) in drying of Moringa leaves after harvesting may lead to some biochemical changes that caused an observedincrease in CS2 concentration comparable to drying at (50 °C). Evidence for formation of dithiocarbamate compound from moringinin moringa leaves are metabolized/detoxified principally by the mercapturic acid pathway. Conjugation with glutathione (GSH)promoted by glutathione transferases gives rise to the corresponding Glucosinolate -. Isothiocyanate conjugates. These undergofurther enzymatic modifications to give rise sequentially to the cysteinylglycine cysteine - Isothiocyanate andN-acetylcysteine-Isothiocyanate conjugates, all of which are dithiocarbamates. The detection of an ion with a m/z value 430.40, withthe following fragments m/z 165.10 and m/z 121.05 respectively, among the ions analyzed by GC-MS gives a clear evidence forformation of dithiocarbamate by addition of glutathione to the isothiocyanate formed from glucosinolate in moringa plant.
基金supported by National Natural Science Foundation of China(grant no.21901196)the Natural Science Basic Research Plan in Shaanxi Province of China(grant no.2020JQ-016)Xi’an Jiaotong University(grant no.71211920000001).
文摘The installation of a trifluoromethyl group onto a nitrogen atom can effectively modulate the basicity of amines owing to the strong electron-withdrawing effect of fluorine.Nevertheless,efficient and opera-tionally simple methods for N-trifluoromethylation of amines are yet to be developed.This protocol involves the use of readily available secondary amines as starting materials,along with CS 2 and AgF as the N-trifluoromethylation reagents,enabling the target molecules to be synthesized in a single step.The versatility of our method was demonstrated by successfully synthesizing N,N-dialkyl and N-(hetero)aromatic N-CF_(3)-containing compounds with various substituents.Moreover,this methodology has been successfully applied to the late-stage modification of complex bioactive molecules,facilitating the synthe-sis of N-CF_(3) drug bioisosteres and N-CF_(3)-tailored amino acids,which would broadly stimulate the drug discovery of N-CF_(3) containing molecules.
基金This study was supported by a grant from the National Natural Science Foundation of China （No.30471442）.
文摘Background Carbon disulfide （CS2） is a commonly used organic solvent. Many epidemiological investigations and animal experiments have indicated that learning and memory ability can be affected to different degrees after long-term exposure to CS2, but the mechanisms are still unclear. The aim of this study was to explore the possible mechanisms of CS2-related impairment of the learning and memory ability of rats, by investigating the effects of CS2 on nitric oxide synthase （NOS） activity and NOS mRNA expression in rat hippocampus. Methods Rat models of toxicity were generated by inhalation of various doses of CS2. After two months of inhaling intoxication, the activities of constitutive NOS （cNOS） and induced NOS （iNOS） in the hippocampus were measured. The levels of neuronal NOS （nNOS） mRNA and iNOS mRNA were measured by semi-quantitative reverse transcription polymerase chain reaction （RT-PCR）. Results cNOS activity was significantly decreased compared with controls, while iNOS activity was changed only slightly. CS2 treatment significantly decreased nNOS mRNA levels, iNOS mRNA levels were significantly increased only at higher doses of CS2. Conclusion The effect of CS2 on learning and memory ability in rats is related to the activity of NOS and the expression of nNOS in the hippocampus.
基金financially supported by the National Basic Research Program of China(2010CB732300)the National Key Technologies R&D Program of China(2007BAJ03B01)
文摘Supported coupling catalysts for CS2 removal were prepared with different activated carbons originated from wood,coconut shell and coal as supports,and their catalytic activities for CS2 removal were tested at ambient temperature.The textural and surface properties of the activated carbons were characterized by nitrogen adsorption,temperature-programmed desorption（TPD）and Boehm titration.The activated carbon support with meso-and macropores,and oxygen-functional groups performs higher CS2 removal ability at ambient temperature.The effects of flow rate,CS2 inlet concentration,temperature and relative humidity on CS2 removal were also investigated.High efficient removal is obtained at temperature of 50-C,space velocity of 2000 h-1,inlet CS2 concentration of 500 mgS/m3 and relative humidity of 20%with the breakthrough sulfur capacity up to 4.3 gS/gCat and working sulfur capacity up to 7 gS/gCat.
基金the National Natural Science Foundation of China (No. 21822108)Sichuan Science and Technology Program (Nos.20CXTD0112, 2020YJ0491)+1 种基金National Key Research and Development Program of China (No. 2018YFC1602101)the Fundamental Research Funds for the Central Universities。
文摘Herein, a facile synthesis of valuable pyrido[1,2-a]pyrimidine-4-thiones is reported via novel thiocarbonylation of C(sp^(3))-H bonds with carbon disulfide(CS_(2)). This reaction features easy availability of substrates,good functional group tolerance, high yields, facile scalability and atom economy. Mechanistic investigations indicate that sulfate anion and sulfuric anhydride anion might be involved in this reaction.
基金the financial support from the Ministry of Science and Technology of China (grants 2012CB215500 and 2013CB933100)the National Natural Science Foundation of China (grants 21573222 and 21103178)
文摘Replacing platinum for catalyzing hydrogen evolution reaction （HER） in acidic medium remains great chal- lenges. Herein, we prepared few-layered MoS2 by ball milling as an efficient catalyst for HER in acidic medium, The activity of as-prepared MoS2 had a strong dependence on the ball milling time, Furthermore, Ketjen Black EC 300J was added into the ball-milled MoS2 followed by a second ball milling, and the resultant MoS2/carbon black hybrid material showed a much higher HER activity than MoS2 and carbon black alone. The enhanced activity of the MoS2/carbon black hybrid material was attributed to the increased abundance of catalytic edge sites of MoS） and excellent electrical coupling to the underlving carbon network.
基金supported by the National Natural Science Foundation of China(Nos.51272113,51272115,51672146)A Project of Shandong Province Higher Educational Science and Technology Program(Nos.J13LA10,J14LA15,J15LA12)Development Program in Science and Technology of Qingdao(No.15-9-1-65-jch)
文摘MoS_2 nanosheet arrays supported on hierarchical nitrogen-doped porous carbon（MoS_2@C） have been synthesized by a facile hydrothermal approach combined with high-temperature calcination.The hierarchical nitrogen-doped porous carbon can serve as three-dimensional conductive frameworks to improve the electronic transport of semiconducting MoS_2.When evaluated as anode material for lithium-ion batteries,the MoS_2@C exhibit enhanced electrochemical performances compared with pure MoS_2 nanosheets,including high capacity（1305.5 mAhg^（-1） at lOOmAg^（-1））,excellent rate capability（438.4mAhg^（-1） at 1000mAg^（-1））.The reasons for the improved electrochemical performances are explored in terms of the high electronic conductivity and the facilitation of lithium ion transport arising from the hierarchical structures of MoS_2@C.
基金supported by the National Natural Science Foundation of China (20501023)the Natural Science Foundation of Guangdong for Doctorial Training Base (5300527)
文摘Rare earth sulfides were systematically synthesized via the sulfurization of their commercial oxide powders using CS2 gas to shorten sulfurization time, and their UV-vis absorption spectra were investigated. The appropriate sulfurization conditions were studied. For the rare earth sulfides with the same crystal structure, the sulfurization temperature showed increasing tendency with the decrease of rare earth element atomic radii. The UV-vis absorption spectra of rare earth sulfides did not depend on the crystal structure of rare earth sulfides, but on the 4f electronic structure of rare earth element. The data showed that the optical band gaps of rare earth sulfides were irregular, and the values ranged from 1.65 to 3.75 eV.
基金Project (No. Y304203) supported by the Natural Science Foundationof Zhejiang Province, China
文摘Waste hops are good sources of flavonoids. Extraction of flavonoids from waste hops (SC-CO2 extracted hops) using supercritical fluids technology was investigated. Various temperatures, pressures and concentrations of ethanol (modifier) and the ratio (w/w) of solvent to material were tested in this study. The results of single factor and orthogonal experiments showed that at 50 °C, 25 MPa, the ratio of solvent to material (50%), ethanol concentration (80%) resulted in maximum extraction yield fla- vonoids (7.8 mg/g). HPLC-MS analysis of the extracts indicated that flavonoids obtained were xanthohumol, the principal prenylflavonoid in hops.
文摘The formation behaviors of terbium sesquisulfide(Tb_2S_3)and holmium sesquisulfide(Ho_2S_3)synthesized via the sulfurization of their oxide powders using CS_2 gas in the range of temperature 673 to 1323 K were investigated. In the sulfurization of Tb_4O_7 powder, Tb_2O_3 and Tb_2O_2S were formed in the initial stage of reaction, and α-Tb_2S_3 was finally formed at higher temperature. For long sulfurization time of 8 h, single-phase α-Tb_2S_3 could be synthesized at 1323 K. In the sulfurization of Ho_2O_3 powder using CS_2 gas, only Ho_2O_2S was formed as an intermediate product. At a sulfurization temperature above 873 K, Ho_2O_2S was formed in the initial stage of reaction, and single-phase δ-Ho_2S_3 was formed at 1323 K for 8 h instead of Ho_2O_2S. Furthermore, the influence of the addition of carbon black to the sulfurization of Ho_2O_3 powder using CS_2 gas was investigated, and the result implied that the reactions were accelerated slightly by the addition of carbon black.
文摘CS2 removal was obtained by coupling catalytic hyidation on bi-functional catalyst. On the hydrolysis active sites, CS2 is hydrolyzed to HES, while on the oxidation active sites, HES is oxidized to elemental S or sulfuric acid deposited on the porous support. The above process can be expressed as follows： CS2 H2O→ COS H2O→ H2S O2→ S/SO4^2-. H2S oxidation eliminates its prohibition on C52 hydrolysis so that the rate of coupling removal CS2 is 5 times higher than that of CS2 hydrolysis. The same active energy of hydrolysis and coupling reaction also indicates that HES oxidation does not change the reaction mechanism of CS2 hydrolysis. Temperature has obvious effect on the process while the mole ratio of O2 concentration to CS2 concentration （O/S） does not, especially in excess of 2.5. The formation of sulfuric acid on the catalyst surface poisons hydrolysis active sites and causes the decrease of left OH^-1 concentration on the catalysts surface. Lower temperature is suggested for this bi-functional catalyst owing to the low yield ratio of S/SO4^2-.
文摘A series of substituted l,4-oxathiane-3-thione derivatives were synthesized via one-pot multicomponent reactions of nitromethane,carbon disulfide and oxiranes in the presence of Et;N in water as the solvent under microwave irradiation.Particularly valuable features of this method include high yields of products,broad substrate scope,short reaction time and straightforward procedure.
基金Project supported by National Natural Science Foundation of China (20501023)Natural Science Foundation of Henan Province (2010A430010)Scientific and Technical Foundation of China National Coal Association (MTKJ2010-357)
文摘In order to investigate the suitability of ternary rare earth sulfide LanCe2 xS3 in plastic application as a red pigment, we prepared LaxCe2 xS3 via the sulfurization of the oxide powders using CS2 gas. In the sulfurization of LaxCe2_xS3, β-phase and y-phase ter- nary rare earth sulfide LaxCe2_xS3 were synthesized at the sulfufization temperature of 1000 and 1250 ℃ for 3 h, respectively. The UV-vis absorption spectra of synthesized LaxCe2_xS3 showed that the absorption wavelengths of 13-phase and y-phase LaxCe2_xS3 samies were in the region of 617-70 nm and 607-53 nm, respectively. They were in red absorption region. Furthermore, the scanning electron microscopy （SEM） results of the synthesized LaxCe2-S3 samples were investigated. The typical SEM microgmphs indicated that the particle sizes of synthesized LaxCe2 xS3 were in the range of 0.5-5 μm.
文摘An efficient synthesis of alkyl bis（dimethylamino）methylenecarbamodithioates via a one-pot reaction between 1,1,3,3- tetramethylguanidine, carbon disulfide and substituted oxiranes, in good yields, is described.
