Two-dimensional(2D)transition metal dichalcogenides(TMD)are atomically thin semiconductors with promising optoelectronic applications across the visible spectrum.However,their intrinsically weak light absorption and t...Two-dimensional(2D)transition metal dichalcogenides(TMD)are atomically thin semiconductors with promising optoelectronic applications across the visible spectrum.However,their intrinsically weak light absorption and the low photoluminescence quantum yield(PLQY)restrict their performance and potential use,especially in ultraviolet(UV)wavelength light ranges.Quantum dots(QD)derived from 2D materials(2D/QD)provide efficient light absorption and emission of which energy can be tuned for desirable light wavelength.In this study,we greatly enhanced the photon absorption and PLQY of monolayer(1L)tungsten disulfide(WS_(2))in the UV range via hybridization with 2D/QD,particularly titanium nitride MXene QD(Ti_(2)N MQD)and graphitic carbon nitride QD(GCNQD).With the hybridization of MQD or GCNQD,1LWS_(2)showed a maximum PL enhancement by 15 times with 300 nm wavelength excitation,while no noticeable enhancement was observed when the excitation photon energy was less than the bandgap of the QD,indicating that UV absorption by the QD played a crucial role in enhancing the light emission of 1L-WS_(2)in our 0D/2D hybrid system.Our findings present a convenient method for enhancing the photo-response of 1L-WS_(2)to UV light and offer exciting possibilities for harvesting UV energy using 1L-TMD.展开更多
In this paper,an absorption spectroscopy measurement method was applied on two atmospheric pressure plasma sources to determine their production of nitric oxide.The concentrations are essential for evaluating the plas...In this paper,an absorption spectroscopy measurement method was applied on two atmospheric pressure plasma sources to determine their production of nitric oxide.The concentrations are essential for evaluating the plasma sources based on the principle of the Dielectric Barrier Discharge(DBD)for applications in plasma medicine.The described method is based on a setup with an electrodeless discharge lamp filled with a mixture of oxygen and nitrogen.One of the emitted wavelengths is an important resonance wavelength of nitric oxide(λ = 226.2 nm).By comparing the absorption behaviour at the minimum and maximum of the spectral absorption cross section of nitric oxide around that wavelength,and measuring the change in intensity by the absorbing plasma,the concentration of nitric oxide inside the plasma can be calculated.The produced nitric oxide concentrations depend on the pulse duration and are in the range of 180 ppm to 1400 ppm,so that a distance of about 10 cm to the respiratory tract is enough to conform to the VDI Guideline 2310.展开更多
We investigated the formation of exciplex and electroluminescent absorption in ultraviolet organic light-emitting diodes(UV OLEDs) using different heterojunction structures.It is found that an energy barrier of over...We investigated the formation of exciplex and electroluminescent absorption in ultraviolet organic light-emitting diodes(UV OLEDs) using different heterojunction structures.It is found that an energy barrier of over 0.3 eV between the emissive layer(EML) and adjacent transport layer facilitates exciplex formation.The electron blocking layer effectively confines electrons in the EML,which contributes to pure UV emission and enhances efficiency.The change in EML thickness generates tunable UV emission from 376 nm to 406 nm.In addition,the UV emission excites low-energy organic function layers and produces photoluminescent emission.In UV OLED,avoiding the exciplex formation and averting light absorption can effectively improve the purity and efficiency.A maximum external quantum efficiency of 1.2%with a UV emission peak of 376 nm is realized.展开更多
A new coordination polymer [Cu2(OH)(nbta)(tib)(H2 O)2]n(1, H3 nbta = 5-nitro-1,2,3-benzenetricarboxylic acid, tib = 1-(4 H-1,2,4-triazol-4-yl)-4-(imidazol-1-yl)benzene) constructed from dimeric Cu(Ⅱ) units has been s...A new coordination polymer [Cu2(OH)(nbta)(tib)(H2 O)2]n(1, H3 nbta = 5-nitro-1,2,3-benzenetricarboxylic acid, tib = 1-(4 H-1,2,4-triazol-4-yl)-4-(imidazol-1-yl)benzene) constructed from dimeric Cu(Ⅱ) units has been synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction analysis. The compound crystallizes in monoclinic system, space group I2/c, with a = 17.8474(9), b = 11.7588(6), c = 21.9221(11) ?, β = 104.419(5)°, V = 4455.7(4) ?3 and Z = 8. Compound 1 is a three-dimensional structure constructed from dimeric Cu(Ⅱ) units and presents a 2-nodal(3,5)-connected net. Moreover, the thermal stability and solid UV-Vis absorption spectra have been investigated.展开更多
60CeO2-40TiO2 thin films were deposited on soda-lime silicate glass substrates by R.F. magnetron sputtering. The effects of heat-treatment on the UV-absorption of the thin films were studied on the 60CeO2-40TiO2 thin ...60CeO2-40TiO2 thin films were deposited on soda-lime silicate glass substrates by R.F. magnetron sputtering. The effects of heat-treatment on the UV-absorption of the thin films were studied on the 60CeO2-40TiO2 thin film with the largest UV cut-off wavelength. The sample films with CeO2:TiO2=60:40 were heated at 773 K, 873 K, 973 K for 30 min. These films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy and spectrometer (XPS). XRD analysis proves that the addition of TiO2 to CeO2 changed the crystalline state of CeO2. But the UV absorption effect of CeO2-TiO2 films with CeO2 crystallite phase is inferior to that of the amorphous phase CeO2-TiO2 films. XPS analysis also indicates that the amorphous phase CeO2-TiO2 films have the most Ce3+ content in these films. Amorphous phase and crystalline phase of the CeO2-TiO2 films have different effects on UV absorption of the thin films.展开更多
The electronic struc ture of nanostructured SiO_(2) was studied by means of ultraviolet-near infrared,absorption spectra.A strong and broad absorption band was observed in the wavelength range of ultraviolet-near infr...The electronic struc ture of nanostructured SiO_(2) was studied by means of ultraviolet-near infrared,absorption spectra.A strong and broad absorption band was observed in the wavelength range of ultraviolet-near infrared light.This band is caused by the electronic transition from the valence band to the defect energy level in the bandgap which was theoretically calculated by using molecular orbital approach.With increasing the annealing temperature,the red shift of this band was observed.The mechanism of this band is discussed.展开更多
New visible transparent, UV absorption, and high infrared reflection properties have been realized by depositing multilayer Si O2/Zn O: Al/Ce O2-Ti O2/Si O2 films onto glass substrates at low temperature by radio freq...New visible transparent, UV absorption, and high infrared reflection properties have been realized by depositing multilayer Si O2/Zn O: Al/Ce O2-Ti O2/Si O2 films onto glass substrates at low temperature by radio frequency magnetron sputtering. Optimum thickness of Si O2, Zn O: Al(ZAO) and Ce O2-Ti O2(CTO) films were designed with the aid of thin film design software. The degree of antireflection can be controlled by adjusting the thickness and refractive index. The outer Si O2 film can diminish the interference coloring and increase the transparency; the inner Si O2 film improves the adhesion of the coating on the glass substrate and prevents Ca2+, Na+ in the glass substrate from entering the ZAO film. The average transmittance in the visible light range increases by nearly 18%-20%, as compared to double layer ZAO/CTO films. And the films display high infrared reflection rate of above 75% in the wavelength range of 10-25 μm and good UV absorption(> 98%) properties. These systems are easy to produce on a large scale at low cost and exhibit high mechanical and chemical durability. The triple functional films with high UV absorption, antireflective and high infrared reflection rate will adapt to application in flat panel display and architectural coating glass, automotive glass, with diminishing light pollution as well as decreasing eye fatigue and increasing comfort.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
During wet complexation denitrification of flue gas,Fe^(Ⅱ)EDTA regeneration,also known as reducing Fe^(Ⅱ)EDTA and Fe^(Ⅱ)EDTA-nitric oxide(NO)to Fe^(Ⅱ)EDTA,is crucial.In this paper,ultraviolet(UV)light was used for...During wet complexation denitrification of flue gas,Fe^(Ⅱ)EDTA regeneration,also known as reducing Fe^(Ⅱ)EDTA and Fe^(Ⅱ)EDTA-nitric oxide(NO)to Fe^(Ⅱ)EDTA,is crucial.In this paper,ultraviolet(UV)light was used for the first time to reduce Fe^(Ⅱ)EDTA-NO.The experimental result demonstrated that Fe^(Ⅱ)EDTA-NO reduction rate increased with UV power increasing,elevated temperature,and initial Fe^(Ⅱ)EDTA-NO concentration decreasing.Fe^(Ⅱ)EDTA-NO reduction rate increased first and then decreased as pH value increased(2.0-10.0).Fe^(Ⅱ)EDTA-NO reduction with UV irradiation presented a first order reaction with respect to Fe^(Ⅱ)EDTA-NO.Compared with other Fe^(Ⅱ)EDTA regeneration methods,Fe^(Ⅱ)EDTA regeneration with UV show more superiority through comprehensive consideration of regeneration rate and procedure.Subsequently,NO absorption experiment by Fe^(Ⅱ)EDTA solution with UV irradiation confirmed that UV can significantly promote the NO removal performance of Fe^(Ⅱ)EDTA.Appropriate oxygen concentration(3%(vol))and acidic environment(pH=4)was favorable for NO removal.With UV power increasing as well as temperature decreasing,NO removal efficiency rose.In addition,the mechanism research indicates that NO from flue gas is mostly converted to NO_(2)-,NO_(3)-,NH_(4)^(+),N_(2),and N_(2)O with Fe^(Ⅱ)EDTA absorption liquid with UV irradiation.UV strengthens NO removal in Fe^(Ⅱ)EDTA absorption liquid by forming a synergistic effect of oxidation-reduction-complexation.Finally,compared with NO removal methods with Fe^(Ⅱ)EDTA,Fe^(Ⅱ)EDTA combined UV system shows prominent technology advantage in terms of economy and secondary pollution.展开更多
Prophyra-334 was prepared by methanol extraction and HPLC methods from marine algae (dried laver). It is a sunscreen compound that has good absorption of ultraviolet radiations in the wavelength ranges of 200-400 nm. ...Prophyra-334 was prepared by methanol extraction and HPLC methods from marine algae (dried laver). It is a sunscreen compound that has good absorption of ultraviolet radiations in the wavelength ranges of 200-400 nm. The absorption maximum wavelength of prophyra-334 is at 334 nm, so defined the name. The mo- lar extinction coefficient (ε) of prophyra-334 in aqueous solution at 334 nm wavelength is 4.23×104. The absorp- tion of prophyra-334 in organic solvents differs in aqueous solutions. In polar organic solvents, the absorption maximum wavelength of prophyra-334 has a slight shift toward longer wavelength compared with that in pure water. On the contrary, in inert non-polar organic solvents, the absorption maximum wavelength and the shape of absorption spectra of prophyra-334 are changed. The effects of organic solvents on prophyra-334 stability sug- gested that: (1) the absorbance of prophyra-334 in water is generally constant at temperature of 60°C in 24 h, meaning that prophyra-334 is quite stable in water; (2) the absorbance of prophyra-334 in ethanol and hexane decreases at the same condition. The stability of prophyra-334 in organic solvents is less than that in aqueous solution. In benzene, the prophyra-334 is very instable.展开更多
I reminisce on my early life in Section 1;on my education in Sections 2 and 3;on the years at Princeton as a research astronomer in Section 4;on the years on the faculty at Chicago in Section 5;on research on Diffuse ...I reminisce on my early life in Section 1;on my education in Sections 2 and 3;on the years at Princeton as a research astronomer in Section 4;on the years on the faculty at Chicago in Section 5;on research on Diffuse Interstellar Bands(DIBs) in Section 6;on construction of the 3.5 m telescope at Apache Point Observatory(APO)in Section 7;on work on the Sloan Digital Sky Survey(SDSS) in Section 8;on work in public education in Chicago in Section 9;and on my travels in Section 10. My main science research is of an observational nature,concerning Galactic and intergalactic interstellar gas. Highlights for me included my work on the orbiting telescope Copernicus, including the discovery of interstellar deuterium;early observations of absorption associated with fivetimes ionized oxygen;and discoveries concerning the phases of gas in the local interstellar medium, based on previously unobservable interstellar UV spectral lines. With other instruments and collaborations, I extended interstellar UV studies to the intergalactic cool gas using quasi-stellar object QSO absorption lines redshifted to the optical part of the spectrum;provided a better definition of the emission and morphological character of the source of absorption lines in QSO spectra;and pursued the identification of the unidentified DIBs. For several of these topics, extensive collaborations with many scientists were essential over many years. The conclusions developed slowly, as I moved from being a graduate student at Chicago, to a research scientist position at Princeton and then to a faculty position at Chicago. At each stage of life, I was exposed to new technologies adaptable to my science and to subsequent projects. From high school days, I encountered several management opportunities which were formative. I have been extremely fortunate both in scientific mentors I had and in experimental opportunities I encountered.展开更多
SCO is a selective dolomite deperessant in the flotation system of collophane and dolomite. However,experi-ments confirmed that reverse phenomenon would occur for some phosphatic mines. In order to explain the SCO dep...SCO is a selective dolomite deperessant in the flotation system of collophane and dolomite. However,experi-ments confirmed that reverse phenomenon would occur for some phosphatic mines. In order to explain the SCO depress-ing mechanism i this paper describes studying results on the ef-fect of dissolved ions on SCO depressing property using ul-traviolet absorption spectra. It is found that the effect of dis-solved ions, especially Mg2+ ?on the SCO adsorption property is strong. When Mg2+ concentration is low,dolomite adsorbs SCO and is depressed. When Mgz+ concentration is more than 90g/t in pulp.SCO adsorption capacity on colophane is obvi-ously greater than that on dolomite,which results in the de-pression of collophane. The adsorption results are consistent with flotation results.展开更多
The nanometer yellow iron oxide was prepared by oxidizing Fe(OH)2 with air, which was verified with XRD and TEM. The result shows that nanometer yellow iron oxide is spindle-shaped and well-distributed with a long a...The nanometer yellow iron oxide was prepared by oxidizing Fe(OH)2 with air, which was verified with XRD and TEM. The result shows that nanometer yellow iron oxide is spindle-shaped and well-distributed with a long axis of 150-200 nm and short axis of 40-50 nm. Ultraviolet (UV) transmittance of the iron oxide shows the great effect of concentration on both transparency and UV ab- sorption, and it has been proven that iron oxide with a concentration of 0.025wt% is preferred. The spectrum of XRD indicates that it is goethite. When the yellow iron is dispersed in sol, given that the wavelength of UV is less than 300 nm, its UV absorption capacity is superior to those of ZnO and TiO2. The absorption capacity of the yellow iron is less than TiO2 and more than ZnO as the wavelength of UV is 300-400 nm.展开更多
The vacuum ultraviolet absorption and emission spectra of rare-gas vander Waals molecules were observed.A large broadening of at least 240Åof Xe first resonance absorption line was obtained at cell presgure 4 atm...The vacuum ultraviolet absorption and emission spectra of rare-gas vander Waals molecules were observed.A large broadening of at least 240Åof Xe first resonance absorption line was obtained at cell presgure 4 atm.Strong continuous emission of heavier rare gases at 1300-3000Åwas obtained using self-triggered condensed discharge in aπ-shaped quartz discharge tube.展开更多
Blood plays an important role in the clinical di-agnosis and treatment, the analysis of blood will be of very important practical significance. The experiment shows that the absorption spectra of blood are of serious ...Blood plays an important role in the clinical di-agnosis and treatment, the analysis of blood will be of very important practical significance. The experiment shows that the absorption spectra of blood are of serious noise in the wave band of 200 to 300 nm, which hides the useful spectral characteristics. The effective separation of the noise was achieved by db4 wavelet transform, and the signals of reconstruction have been obviously improved in the noise serious wave band, reflecting some useful information. The absorption peaks of different samples are displaced to some degrees. The correlation between absorbance at 278nm and blood fat concentration is no significant and random. Based on the evident correlation between serum absorption spectrum and blood fat con-centration in the wave band of 265 to 282nm, a neural network model was built to forecast the blood fat concentration, bringing a relatively good prediction. This provides a new spectral test method of blood fat concentration.展开更多
The demand and pursuit of chemical entities with UV filtration and antioxidant properties for enhanced photoprotection have been driven in recent times by acute exposure of humans to solar ultraviolet radiations. The ...The demand and pursuit of chemical entities with UV filtration and antioxidant properties for enhanced photoprotection have been driven in recent times by acute exposure of humans to solar ultraviolet radiations. The structural, electronic, antioxidant and UV absorption properties of drometrizole (PBT) and designed ortho-substituted derivatives are reported via DFT and TD-DFT in the gas and aqueous phases. DFT and TD-DFT computations were performed at the M062x-D3Zero/6-311++G(d,p)//B97-3c and PBE0-D3(BJ)/def2-TZVP levels of theory respectively. Reaction enthalpies related to hydrogen atom transfer (HAT), single-electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) mechanisms were computed and compared with those of phenol. Results show that the presence of -NH2 substituent reduces the O-H bond dissociation enthalpy and ionization potential, while that of -CN increases the proton affinity. The HAT and SPLET mechanisms are the most plausible in the gas and aqueous phases respectively. The molecule with the -NH2 substituent (PBT1) was identified to be the compound with the highest antioxidant activity. The UV spectra of the studied compounds are characterized by two bands in the 280 - 400 nm regions. Results from this study provide a better comprehension antioxidant mechanism of drometrizole and present a new perspective for the design of electron-donor antioxidant molecules with enhanced antioxidant-photoprotective efficiencies for applications in commercial sunscreens.展开更多
Syntheses of zince oxide(ZnO) nanoparticles by direct precipitation and surface modification with oleic acid were reported. ZnO nanoparticles were characterized via X-ray diffractometry(XRD), transmission electron...Syntheses of zince oxide(ZnO) nanoparticles by direct precipitation and surface modification with oleic acid were reported. ZnO nanoparticles were characterized via X-ray diffractometry(XRD), transmission electron microscopy(TEM), infrared spectroscopy(IR) and UV-Vis spectroscopy. The prepared ZnO nanoparticles were nearly spherical and highly crystalline with an average size of 29 nm. In addition, high UV-light absorption properties of oleic acid surface modified ZnO nanoparticles were successfully obtained for a dispersion of ZnO nanoparticles in ethanol.展开更多
基金supported by National Research Foundation of Korea(NRF)funded by the Ministry of Education(2021R1A6A1A030396962022R1A2C2009412).Anir S.Sharbirin,Rebekah E.Kong and Wendy B.Mato contributed equally to this work.
文摘Two-dimensional(2D)transition metal dichalcogenides(TMD)are atomically thin semiconductors with promising optoelectronic applications across the visible spectrum.However,their intrinsically weak light absorption and the low photoluminescence quantum yield(PLQY)restrict their performance and potential use,especially in ultraviolet(UV)wavelength light ranges.Quantum dots(QD)derived from 2D materials(2D/QD)provide efficient light absorption and emission of which energy can be tuned for desirable light wavelength.In this study,we greatly enhanced the photon absorption and PLQY of monolayer(1L)tungsten disulfide(WS_(2))in the UV range via hybridization with 2D/QD,particularly titanium nitride MXene QD(Ti_(2)N MQD)and graphitic carbon nitride QD(GCNQD).With the hybridization of MQD or GCNQD,1LWS_(2)showed a maximum PL enhancement by 15 times with 300 nm wavelength excitation,while no noticeable enhancement was observed when the excitation photon energy was less than the bandgap of the QD,indicating that UV absorption by the QD played a crucial role in enhancing the light emission of 1L-WS_(2)in our 0D/2D hybrid system.Our findings present a convenient method for enhancing the photo-response of 1L-WS_(2)to UV light and offer exciting possibilities for harvesting UV energy using 1L-TMD.
文摘In this paper,an absorption spectroscopy measurement method was applied on two atmospheric pressure plasma sources to determine their production of nitric oxide.The concentrations are essential for evaluating the plasma sources based on the principle of the Dielectric Barrier Discharge(DBD)for applications in plasma medicine.The described method is based on a setup with an electrodeless discharge lamp filled with a mixture of oxygen and nitrogen.One of the emitted wavelengths is an important resonance wavelength of nitric oxide(λ = 226.2 nm).By comparing the absorption behaviour at the minimum and maximum of the spectral absorption cross section of nitric oxide around that wavelength,and measuring the change in intensity by the absorbing plasma,the concentration of nitric oxide inside the plasma can be calculated.The produced nitric oxide concentrations depend on the pulse duration and are in the range of 180 ppm to 1400 ppm,so that a distance of about 10 cm to the respiratory tract is enough to conform to the VDI Guideline 2310.
基金supported by the National Natural Science Foundation of China(Grant Nos.61136003 and 61275041)the Guangxi Provincial Natural Science Foundation,China(Grant No.2012GXNSFBA053168)
文摘We investigated the formation of exciplex and electroluminescent absorption in ultraviolet organic light-emitting diodes(UV OLEDs) using different heterojunction structures.It is found that an energy barrier of over 0.3 eV between the emissive layer(EML) and adjacent transport layer facilitates exciplex formation.The electron blocking layer effectively confines electrons in the EML,which contributes to pure UV emission and enhances efficiency.The change in EML thickness generates tunable UV emission from 376 nm to 406 nm.In addition,the UV emission excites low-energy organic function layers and produces photoluminescent emission.In UV OLED,avoiding the exciplex formation and averting light absorption can effectively improve the purity and efficiency.A maximum external quantum efficiency of 1.2%with a UV emission peak of 376 nm is realized.
基金supported by the National Natural Science Foundation of China(21401097)
文摘A new coordination polymer [Cu2(OH)(nbta)(tib)(H2 O)2]n(1, H3 nbta = 5-nitro-1,2,3-benzenetricarboxylic acid, tib = 1-(4 H-1,2,4-triazol-4-yl)-4-(imidazol-1-yl)benzene) constructed from dimeric Cu(Ⅱ) units has been synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction analysis. The compound crystallizes in monoclinic system, space group I2/c, with a = 17.8474(9), b = 11.7588(6), c = 21.9221(11) ?, β = 104.419(5)°, V = 4455.7(4) ?3 and Z = 8. Compound 1 is a three-dimensional structure constructed from dimeric Cu(Ⅱ) units and presents a 2-nodal(3,5)-connected net. Moreover, the thermal stability and solid UV-Vis absorption spectra have been investigated.
基金the National Natural Science Foundation of China(No.51032005)the Fundamental Research Funds for the Central Universities(Wuhan University of Technology)+1 种基金the China Postdoctoral Science Foundation(No.2012M511285)the Fund for the Young Innovative Team(Hubei University of Education)(No.2012KQ05)
文摘60CeO2-40TiO2 thin films were deposited on soda-lime silicate glass substrates by R.F. magnetron sputtering. The effects of heat-treatment on the UV-absorption of the thin films were studied on the 60CeO2-40TiO2 thin film with the largest UV cut-off wavelength. The sample films with CeO2:TiO2=60:40 were heated at 773 K, 873 K, 973 K for 30 min. These films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy and spectrometer (XPS). XRD analysis proves that the addition of TiO2 to CeO2 changed the crystalline state of CeO2. But the UV absorption effect of CeO2-TiO2 films with CeO2 crystallite phase is inferior to that of the amorphous phase CeO2-TiO2 films. XPS analysis also indicates that the amorphous phase CeO2-TiO2 films have the most Ce3+ content in these films. Amorphous phase and crystalline phase of the CeO2-TiO2 films have different effects on UV absorption of the thin films.
文摘The electronic struc ture of nanostructured SiO_(2) was studied by means of ultraviolet-near infrared,absorption spectra.A strong and broad absorption band was observed in the wavelength range of ultraviolet-near infrared light.This band is caused by the electronic transition from the valence band to the defect energy level in the bandgap which was theoretically calculated by using molecular orbital approach.With increasing the annealing temperature,the red shift of this band was observed.The mechanism of this band is discussed.
基金Funded by the Natural Science Foundation of Hubei Province(No.2014CFB563)the key Technology Innovation Project of Hubei Province(No.2013AAA005)China Postdoctoral Science Foundation(Nos.2013T60752 and 2012M511689)
文摘New visible transparent, UV absorption, and high infrared reflection properties have been realized by depositing multilayer Si O2/Zn O: Al/Ce O2-Ti O2/Si O2 films onto glass substrates at low temperature by radio frequency magnetron sputtering. Optimum thickness of Si O2, Zn O: Al(ZAO) and Ce O2-Ti O2(CTO) films were designed with the aid of thin film design software. The degree of antireflection can be controlled by adjusting the thickness and refractive index. The outer Si O2 film can diminish the interference coloring and increase the transparency; the inner Si O2 film improves the adhesion of the coating on the glass substrate and prevents Ca2+, Na+ in the glass substrate from entering the ZAO film. The average transmittance in the visible light range increases by nearly 18%-20%, as compared to double layer ZAO/CTO films. And the films display high infrared reflection rate of above 75% in the wavelength range of 10-25 μm and good UV absorption(> 98%) properties. These systems are easy to produce on a large scale at low cost and exhibit high mechanical and chemical durability. The triple functional films with high UV absorption, antireflective and high infrared reflection rate will adapt to application in flat panel display and architectural coating glass, automotive glass, with diminishing light pollution as well as decreasing eye fatigue and increasing comfort.
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supported by National Natural Science Foundation of China(52260012)Natural Science Foundation of Jiangxi Province(20232BAB203053,20212ACB213001,20232BAB203033)+1 种基金General Project of Jiangxi Province Key Research and Development Program(20192BBG70008)Training Plan for Academic and Technical Leaders of Major Disciplines in Jiangxi Province-youth Talent Project(20232BCJ23047).
文摘During wet complexation denitrification of flue gas,Fe^(Ⅱ)EDTA regeneration,also known as reducing Fe^(Ⅱ)EDTA and Fe^(Ⅱ)EDTA-nitric oxide(NO)to Fe^(Ⅱ)EDTA,is crucial.In this paper,ultraviolet(UV)light was used for the first time to reduce Fe^(Ⅱ)EDTA-NO.The experimental result demonstrated that Fe^(Ⅱ)EDTA-NO reduction rate increased with UV power increasing,elevated temperature,and initial Fe^(Ⅱ)EDTA-NO concentration decreasing.Fe^(Ⅱ)EDTA-NO reduction rate increased first and then decreased as pH value increased(2.0-10.0).Fe^(Ⅱ)EDTA-NO reduction with UV irradiation presented a first order reaction with respect to Fe^(Ⅱ)EDTA-NO.Compared with other Fe^(Ⅱ)EDTA regeneration methods,Fe^(Ⅱ)EDTA regeneration with UV show more superiority through comprehensive consideration of regeneration rate and procedure.Subsequently,NO absorption experiment by Fe^(Ⅱ)EDTA solution with UV irradiation confirmed that UV can significantly promote the NO removal performance of Fe^(Ⅱ)EDTA.Appropriate oxygen concentration(3%(vol))and acidic environment(pH=4)was favorable for NO removal.With UV power increasing as well as temperature decreasing,NO removal efficiency rose.In addition,the mechanism research indicates that NO from flue gas is mostly converted to NO_(2)-,NO_(3)-,NH_(4)^(+),N_(2),and N_(2)O with Fe^(Ⅱ)EDTA absorption liquid with UV irradiation.UV strengthens NO removal in Fe^(Ⅱ)EDTA absorption liquid by forming a synergistic effect of oxidation-reduction-complexation.Finally,compared with NO removal methods with Fe^(Ⅱ)EDTA,Fe^(Ⅱ)EDTA combined UV system shows prominent technology advantage in terms of economy and secondary pollution.
基金This study was supported by SRF for ROCS, SEM and Natural ScienceFoundation of Qingdao (No. 04-2-JZ-110)
文摘Prophyra-334 was prepared by methanol extraction and HPLC methods from marine algae (dried laver). It is a sunscreen compound that has good absorption of ultraviolet radiations in the wavelength ranges of 200-400 nm. The absorption maximum wavelength of prophyra-334 is at 334 nm, so defined the name. The mo- lar extinction coefficient (ε) of prophyra-334 in aqueous solution at 334 nm wavelength is 4.23×104. The absorp- tion of prophyra-334 in organic solvents differs in aqueous solutions. In polar organic solvents, the absorption maximum wavelength of prophyra-334 has a slight shift toward longer wavelength compared with that in pure water. On the contrary, in inert non-polar organic solvents, the absorption maximum wavelength and the shape of absorption spectra of prophyra-334 are changed. The effects of organic solvents on prophyra-334 stability sug- gested that: (1) the absorbance of prophyra-334 in water is generally constant at temperature of 60°C in 24 h, meaning that prophyra-334 is quite stable in water; (2) the absorbance of prophyra-334 in ethanol and hexane decreases at the same condition. The stability of prophyra-334 in organic solvents is less than that in aqueous solution. In benzene, the prophyra-334 is very instable.
文摘I reminisce on my early life in Section 1;on my education in Sections 2 and 3;on the years at Princeton as a research astronomer in Section 4;on the years on the faculty at Chicago in Section 5;on research on Diffuse Interstellar Bands(DIBs) in Section 6;on construction of the 3.5 m telescope at Apache Point Observatory(APO)in Section 7;on work on the Sloan Digital Sky Survey(SDSS) in Section 8;on work in public education in Chicago in Section 9;and on my travels in Section 10. My main science research is of an observational nature,concerning Galactic and intergalactic interstellar gas. Highlights for me included my work on the orbiting telescope Copernicus, including the discovery of interstellar deuterium;early observations of absorption associated with fivetimes ionized oxygen;and discoveries concerning the phases of gas in the local interstellar medium, based on previously unobservable interstellar UV spectral lines. With other instruments and collaborations, I extended interstellar UV studies to the intergalactic cool gas using quasi-stellar object QSO absorption lines redshifted to the optical part of the spectrum;provided a better definition of the emission and morphological character of the source of absorption lines in QSO spectra;and pursued the identification of the unidentified DIBs. For several of these topics, extensive collaborations with many scientists were essential over many years. The conclusions developed slowly, as I moved from being a graduate student at Chicago, to a research scientist position at Princeton and then to a faculty position at Chicago. At each stage of life, I was exposed to new technologies adaptable to my science and to subsequent projects. From high school days, I encountered several management opportunities which were formative. I have been extremely fortunate both in scientific mentors I had and in experimental opportunities I encountered.
文摘SCO is a selective dolomite deperessant in the flotation system of collophane and dolomite. However,experi-ments confirmed that reverse phenomenon would occur for some phosphatic mines. In order to explain the SCO depress-ing mechanism i this paper describes studying results on the ef-fect of dissolved ions on SCO depressing property using ul-traviolet absorption spectra. It is found that the effect of dis-solved ions, especially Mg2+ ?on the SCO adsorption property is strong. When Mg2+ concentration is low,dolomite adsorbs SCO and is depressed. When Mgz+ concentration is more than 90g/t in pulp.SCO adsorption capacity on colophane is obvi-ously greater than that on dolomite,which results in the de-pression of collophane. The adsorption results are consistent with flotation results.
基金This work was financially supported by the Construct Plan of Cooperation Project from the Beijing Education Committee (No.XK100080432).
文摘The nanometer yellow iron oxide was prepared by oxidizing Fe(OH)2 with air, which was verified with XRD and TEM. The result shows that nanometer yellow iron oxide is spindle-shaped and well-distributed with a long axis of 150-200 nm and short axis of 40-50 nm. Ultraviolet (UV) transmittance of the iron oxide shows the great effect of concentration on both transparency and UV ab- sorption, and it has been proven that iron oxide with a concentration of 0.025wt% is preferred. The spectrum of XRD indicates that it is goethite. When the yellow iron is dispersed in sol, given that the wavelength of UV is less than 300 nm, its UV absorption capacity is superior to those of ZnO and TiO2. The absorption capacity of the yellow iron is less than TiO2 and more than ZnO as the wavelength of UV is 300-400 nm.
文摘The vacuum ultraviolet absorption and emission spectra of rare-gas vander Waals molecules were observed.A large broadening of at least 240Åof Xe first resonance absorption line was obtained at cell presgure 4 atm.Strong continuous emission of heavier rare gases at 1300-3000Åwas obtained using self-triggered condensed discharge in aπ-shaped quartz discharge tube.
文摘Blood plays an important role in the clinical di-agnosis and treatment, the analysis of blood will be of very important practical significance. The experiment shows that the absorption spectra of blood are of serious noise in the wave band of 200 to 300 nm, which hides the useful spectral characteristics. The effective separation of the noise was achieved by db4 wavelet transform, and the signals of reconstruction have been obviously improved in the noise serious wave band, reflecting some useful information. The absorption peaks of different samples are displaced to some degrees. The correlation between absorbance at 278nm and blood fat concentration is no significant and random. Based on the evident correlation between serum absorption spectrum and blood fat con-centration in the wave band of 265 to 282nm, a neural network model was built to forecast the blood fat concentration, bringing a relatively good prediction. This provides a new spectral test method of blood fat concentration.
文摘The demand and pursuit of chemical entities with UV filtration and antioxidant properties for enhanced photoprotection have been driven in recent times by acute exposure of humans to solar ultraviolet radiations. The structural, electronic, antioxidant and UV absorption properties of drometrizole (PBT) and designed ortho-substituted derivatives are reported via DFT and TD-DFT in the gas and aqueous phases. DFT and TD-DFT computations were performed at the M062x-D3Zero/6-311++G(d,p)//B97-3c and PBE0-D3(BJ)/def2-TZVP levels of theory respectively. Reaction enthalpies related to hydrogen atom transfer (HAT), single-electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) mechanisms were computed and compared with those of phenol. Results show that the presence of -NH2 substituent reduces the O-H bond dissociation enthalpy and ionization potential, while that of -CN increases the proton affinity. The HAT and SPLET mechanisms are the most plausible in the gas and aqueous phases respectively. The molecule with the -NH2 substituent (PBT1) was identified to be the compound with the highest antioxidant activity. The UV spectra of the studied compounds are characterized by two bands in the 280 - 400 nm regions. Results from this study provide a better comprehension antioxidant mechanism of drometrizole and present a new perspective for the design of electron-donor antioxidant molecules with enhanced antioxidant-photoprotective efficiencies for applications in commercial sunscreens.
基金Supported by the Key Project of the National Eleventh Five-Year Research Programe of China(No.2008BAE66B00)
文摘Syntheses of zince oxide(ZnO) nanoparticles by direct precipitation and surface modification with oleic acid were reported. ZnO nanoparticles were characterized via X-ray diffractometry(XRD), transmission electron microscopy(TEM), infrared spectroscopy(IR) and UV-Vis spectroscopy. The prepared ZnO nanoparticles were nearly spherical and highly crystalline with an average size of 29 nm. In addition, high UV-light absorption properties of oleic acid surface modified ZnO nanoparticles were successfully obtained for a dispersion of ZnO nanoparticles in ethanol.