The microstructure and phase composition of high-alumina,chromic oxide,and AZS/Cr refractories containing 30%and 60%(by mass)Cr_(2)O_(3) after exposure to aluminaboronsilicate glasses and basalt melts depending on the...The microstructure and phase composition of high-alumina,chromic oxide,and AZS/Cr refractories containing 30%and 60%(by mass)Cr_(2)O_(3) after exposure to aluminaboronsilicate glasses and basalt melts depending on the type of melts and temperature have been studied.The mechanisms of refractory corrosion by the used melts and the factors contributing to the inhibition of corrosion development have been investigated by the method of petrographic analysis.On the basis of obtained results,the use of high-alumina,chromic oxide,and AZS/Cr refractories in the sections of glass furnace linings,experiencing the intensive impact of aluminaboronsilicate glasses and basalt melts,has been confirmed and scientifically substantiated.展开更多
A new green technique for producing chromic acid via an electrosynthesis method was studied.The kinetic experiments were carried out on the direct electrosynthesis reaction of chromic acid from sodium dichromate in a ...A new green technique for producing chromic acid via an electrosynthesis method was studied.The kinetic experiments were carried out on the direct electrosynthesis reaction of chromic acid from sodium dichromate in a self-made electrosynthesis reactor with a multiple-unit metal oxides combination anode,a stainless steel cathode,and a reinforcing combination Nafion 324 cation exchange membrane.The apparent kinetic data were experimentally measured at different reaction time under different reaction conditions by relating many essential cell processes and their interaction,as well as their synergistic effect to the whole electrochemical synthesis process.The results show that the electrosynthesis reaction process follows a quasi-first-order reaction kinetic characteristic.The apparent kinetic model of the electrosynthesis reaction was established,and kinetic parameters were calculated.展开更多
This paper reports that highly purified hexagonal WO3 nanowires are synthesized by a simple hydrothermal method. The as-synthesized WO3 nanowires are investigated in detail by ultraviolet-visible-near infrared spectro...This paper reports that highly purified hexagonal WO3 nanowires are synthesized by a simple hydrothermal method. The as-synthesized WO3 nanowires are investigated in detail by ultraviolet-visible-near infrared spectroscopy and electrical transport measurements under different conditions. It finds that the optical band gap and the diffuse reflection coefficient in the wavelength region above 450 nm of WO3 nanowires decrease observably upon exposure to ultraviolet light or NH3 gas. It is also found that there are electrons being trapped or released in individual WO3 nanowires when scanning bias voltage in different directions upon exposure to ultraviolet and NH3 gas. The experimental results suggest that the chromic properties might be attributed to the injection/extraction of hydrogen ions induced by ultraviolet light irradiation in air or creation/annihilation of oxygen vacancies induced by NH3 gas exposure, which serve as colour centres and trap electrons as polarons. The experimental results also suggest that the hexagonal WO3 nanowires will be a good candidate for sensing reduced gas such as NH3.展开更多
Cathode ablation is one of the dominant limitations for extending the maximum operating time of arc heaters.In this work,the arc ablation behaviors and mechanisms of commercial CuCr10,CuCr25,and CuCr50 cathodes were i...Cathode ablation is one of the dominant limitations for extending the maximum operating time of arc heaters.In this work,the arc ablation behaviors and mechanisms of commercial CuCr10,CuCr25,and CuCr50 cathodes were investigated for pure copper and pure chromium cathodes.The discharging homogeneity was improved with the increase of chromium content in the cathodes,which was attributed to the formed chromic oxide layer.The CuCr50 cathodes exhibited the lowest ablation rate with a reduction of 27.0%compared to the copper cathodes.The chromic oxide formed in the pit protected the bottom matrix,leading to a homogeneous ablation process.The mechanism for the improved homogeneous ablation behaviors of the CuCr50 cathodes was proposed and featured by the suppression of deep pits and the dispersion of arc foot.Future attention will be focused on designing composite cathodes with an anti-ablation surface layer and a good conductive matrix.展开更多
The graft copolymerization of acrylic acid (AA) with unswollen and swollen ramie fibers using chromic acid (H 2CrO 4) as the initiator has been studied in the presence of air. The effects of initiator concentration,...The graft copolymerization of acrylic acid (AA) with unswollen and swollen ramie fibers using chromic acid (H 2CrO 4) as the initiator has been studied in the presence of air. The effects of initiator concentration, monomer concentration, perchloric acid (HClO 4) concentration, time of polymerization, reaction temperature, and amount of ramie fibers on the graft percentage have been found out. The graft copolymer was characterized by IR spectra, scanning electron microscopy(SEM), differential thermal analysis (DTA), and thermogravimertric analysis (TGA).展开更多
Radiochromic film for spot-scanning QA provides high spatial resolution and efficiency gains from one-shot irradiation for multiple depths. However, calibration can be a tedious procedure which may limit widespread us...Radiochromic film for spot-scanning QA provides high spatial resolution and efficiency gains from one-shot irradiation for multiple depths. However, calibration can be a tedious procedure which may limit widespread use. Moreover, since there may be an energy dependence, which manifests as a depth dependence, this may require additional measurements for each patient. We present a one-scan protocol to simplify the procedure. A calibration using an EBT3 film, exposed by a 6-level step-wedge plan on a Proteus®PLUS proton system (IBA, Belgium), was performed at depths of 18, 20, 24 cm using Plastic Water®(CIRS, Norfolk, VA). The calibration doses ranged from 65 - 250 cGy (RBE) (relative biological effectiveness) for proton energies of 170 - 200 MeV. A clinical prostate + nodes plan was used for validation. The planar doses at selected depths were measured with EBT3 films and analyzed using one-scan protocol (one-scan digitization of QA film and at least one film exposed to a known dose). The gamma passing rates, dose-difference maps, and profiles of 2D planar doses measured with EBT3 film and IBA MatriXX-PT, versus the RayStation TPS calculations were analyzed and compared. The EBT3 film measurement results matched well with the TPS calculation data with an average passing rate of ~95% for 2%/2 mm and slightly lower passing rates were obtained from an ion chamber array detector. We were able to demonstrate that the use of a proton step-wedge provided clinically acceptable results and minimized variations between film-scanner orientation, inter-scan, and scanning conditions. Furthermore, for relative dosimetry (calibration is not done at the time of experiment), it could be derived from no more than two films exposed to known doses (one could be zero) for rescaling the master calibration curve at each depth. The sensitivity of the calibration to depth variations has been explored. One-scan protocol results appear to be comparable to that of the ion chamber array detector. The use of a proton step-wedge for calibration of EBT3 film potentially increases efficiency in patient-specific QA of proton beams.展开更多
The ultra-fine chromic oxide powder was prepared by a novel gas-solid reduction reaction.Na2CrO4 was firstly reduced with hydrogen at 400-600 ℃.The obtained reduction products,mainly the mixture of NaCrO2 and sodium ...The ultra-fine chromic oxide powder was prepared by a novel gas-solid reduction reaction.Na2CrO4 was firstly reduced with hydrogen at 400-600 ℃.The obtained reduction products,mainly the mixture of NaCrO2 and sodium hydroxide（NaOH）,were converted into chromic oxide through hydrolysis followed by calcination.The obtained chromic oxide product was characterized by powder X-ray diffraction（XRD） and SEM.The results show that the hydrolysis process of sodium chromite is the key step and lower reduction temperature helps intensify the hydrolysis process.展开更多
Organic chromic materials that respond to external stimuli, especially in the solid state, have sparked extensive interest owing to their potential use as smart materials. In particular, the availability of chromic ma...Organic chromic materials that respond to external stimuli, especially in the solid state, have sparked extensive interest owing to their potential use as smart materials. In particular, the availability of chromic materials, which emit fluorescence or phosphorescence in the deep penetrating, near-infrared（NIR）region, has led to great improvements in imaging. Various methods that were commonly applied to construct chromic materials, have been reformed to develop the novel type of compounds, and some have received rewards with excellent fingdings. Relevant research achievements of practical applications have showed their potential with the changes that locate in the NIR region, while further in-depth explorations about the inherent chromic chromism are underway. In this review, several representative studies, which have led the development of responsive organic chromic materials with near-infrared emission, will be discussed.展开更多
This work presents the results of investigations to develop and implement methods to effectively collect and purify infiltrates from heaps, situated in the region of Alwernia near Cracow, where more than 3 million ton...This work presents the results of investigations to develop and implement methods to effectively collect and purify infiltrates from heaps, situated in the region of Alwernia near Cracow, where more than 3 million tonnes of waste material resulting from the production of chromium compounds have been stored. It describes a system for the protection of groundwater from these infiltrates which contain 50-400 g m-3 Cr6+, as well as the effectiveness of cheap and simple chemical methods to purify these chromic wastewaters. The infiltrate collection system and the most effective method to decrease the concentration of Cr6+ to a level below 0.1 ppm, as required by Polish and European Union regulations, were implemented in the Alwernia Chemical Works S. A. in the years 1998-1999.展开更多
Chromic materials with multi-stimuli responses have received tremendous attention from industry and academia for their potential applications in smart windows,data storage,military camouflage,molecular switches,modula...Chromic materials with multi-stimuli responses have received tremendous attention from industry and academia for their potential applications in smart windows,data storage,military camouflage,molecular switches,modulators,etc.To develop multi-stimuli-responsive color-changing materials with high sensi-tivity and high stability,a polyoxometalate-based copper-viologen framework,formulated as Cu_(2)(H_(2)O)_(2)(L)_(2)[PW_(12)O_(40)][OH^(-)]·2H_(2)O(HNU-97,H_(2)L^(2+)=1,10-(1,4-phenylenebis(methylene))bis(4-carboxypyridinium)),was prepared by a mild one-step self-assembly strategy.Structural analysis shows that HNU-97 presents a supramolecular structure formed by a one-dimensional copper-viologen frame-work and polyoxometalates through rich hydrogen bonds,anion-πinteractions,etc.Discoloration studies show that HNU-97 exhibits reversible and rapid response characteristics to various external stimuli,such as 10 s to UV radiation,5 min to heating,and 5 min to ammonium/amine vapors.This mechanism re-veals that different external excitation sources lead to different preferential transfer directions of electrons,resulting in different discoloration phenomena.To construct stimuli-chromic materials with good mechanical properties,we successfully introduced HNU-97 into the poly(vinyl alcohol)(PVA)/glycerol(Gly)hydrogel to obtain a composite HNU-97@PVA/Gly.Remarkably,HNU-97@PVA/Gly combines the merits of each component and can achieve signifi-cant response discoloration behavior under both UV irradiation and ammonia atmosphere.This work will provide an idea for the construction of multiple stimuli-responsive materials.展开更多
The reaction of Mg^(2+)and 5-{1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl}terephthalic acid(H_(2)L)leads to two metal-organic frameworks,[Mg(L)(DMF)_(2)(H_(2)O)_(2)]_(2)·5DMF·2H_(2)O(1)with a 1D structure and...The reaction of Mg^(2+)and 5-{1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl}terephthalic acid(H_(2)L)leads to two metal-organic frameworks,[Mg(L)(DMF)_(2)(H_(2)O)_(2)]_(2)·5DMF·2H_(2)O(1)with a 1D structure and[Mg_(2)(L)_(2)(DMSO)_(3)(H_(2)O)](2)with a 2D(4,4)-net structure.Interestingly,the two compounds exhibit distinct luminescent responses to external mechanical stimuli.1 exhibited exceptional resistance mechanical chromic luminescence(RMCL),which can be attributed to the predominant hydrogen bonds and the presence of high-boiling-point solvent molecules within its structure.2 had a reversible MCL property,which can be attributed to the dominantπ-πweak interactions,coupled with the reversible destruction/restoration of its crystallinity under grinding/fumigation.CCDC:2410963,1;2410964,2.展开更多
文摘The microstructure and phase composition of high-alumina,chromic oxide,and AZS/Cr refractories containing 30%and 60%(by mass)Cr_(2)O_(3) after exposure to aluminaboronsilicate glasses and basalt melts depending on the type of melts and temperature have been studied.The mechanisms of refractory corrosion by the used melts and the factors contributing to the inhibition of corrosion development have been investigated by the method of petrographic analysis.On the basis of obtained results,the use of high-alumina,chromic oxide,and AZS/Cr refractories in the sections of glass furnace linings,experiencing the intensive impact of aluminaboronsilicate glasses and basalt melts,has been confirmed and scientifically substantiated.
基金Supported by the National Natural Science Foundation of China(No.20676136)
文摘A new green technique for producing chromic acid via an electrosynthesis method was studied.The kinetic experiments were carried out on the direct electrosynthesis reaction of chromic acid from sodium dichromate in a self-made electrosynthesis reactor with a multiple-unit metal oxides combination anode,a stainless steel cathode,and a reinforcing combination Nafion 324 cation exchange membrane.The apparent kinetic data were experimentally measured at different reaction time under different reaction conditions by relating many essential cell processes and their interaction,as well as their synergistic effect to the whole electrochemical synthesis process.The results show that the electrosynthesis reaction process follows a quasi-first-order reaction kinetic characteristic.The apparent kinetic model of the electrosynthesis reaction was established,and kinetic parameters were calculated.
基金supported by the Program for New Century Excellent Talents in University (Grant No. NCET-07-0278)the Hunan Provincial Natural Science Fund of China (Grant Nos. 08JJ1001 and 07JJ6009)+1 种基金the Major Research plan of National Natural Science Foundation of China (Grant No. 90606010)the Program for Excellent Talents in Hunan Normal University,China(Grant No. 070623)
文摘This paper reports that highly purified hexagonal WO3 nanowires are synthesized by a simple hydrothermal method. The as-synthesized WO3 nanowires are investigated in detail by ultraviolet-visible-near infrared spectroscopy and electrical transport measurements under different conditions. It finds that the optical band gap and the diffuse reflection coefficient in the wavelength region above 450 nm of WO3 nanowires decrease observably upon exposure to ultraviolet light or NH3 gas. It is also found that there are electrons being trapped or released in individual WO3 nanowires when scanning bias voltage in different directions upon exposure to ultraviolet and NH3 gas. The experimental results suggest that the chromic properties might be attributed to the injection/extraction of hydrogen ions induced by ultraviolet light irradiation in air or creation/annihilation of oxygen vacancies induced by NH3 gas exposure, which serve as colour centres and trap electrons as polarons. The experimental results also suggest that the hexagonal WO3 nanowires will be a good candidate for sensing reduced gas such as NH3.
基金This work is financially supported by the National Key R&D Program of China(No.2017YFB1200800)the National Natural Science Foundation of China(Nos.11725210,11572281)the Fundamental Research Funds for the Central Universities(No.2018XZZX001-05)。
文摘Cathode ablation is one of the dominant limitations for extending the maximum operating time of arc heaters.In this work,the arc ablation behaviors and mechanisms of commercial CuCr10,CuCr25,and CuCr50 cathodes were investigated for pure copper and pure chromium cathodes.The discharging homogeneity was improved with the increase of chromium content in the cathodes,which was attributed to the formed chromic oxide layer.The CuCr50 cathodes exhibited the lowest ablation rate with a reduction of 27.0%compared to the copper cathodes.The chromic oxide formed in the pit protected the bottom matrix,leading to a homogeneous ablation process.The mechanism for the improved homogeneous ablation behaviors of the CuCr50 cathodes was proposed and featured by the suppression of deep pits and the dispersion of arc foot.Future attention will be focused on designing composite cathodes with an anti-ablation surface layer and a good conductive matrix.
文摘The graft copolymerization of acrylic acid (AA) with unswollen and swollen ramie fibers using chromic acid (H 2CrO 4) as the initiator has been studied in the presence of air. The effects of initiator concentration, monomer concentration, perchloric acid (HClO 4) concentration, time of polymerization, reaction temperature, and amount of ramie fibers on the graft percentage have been found out. The graft copolymer was characterized by IR spectra, scanning electron microscopy(SEM), differential thermal analysis (DTA), and thermogravimertric analysis (TGA).
文摘Radiochromic film for spot-scanning QA provides high spatial resolution and efficiency gains from one-shot irradiation for multiple depths. However, calibration can be a tedious procedure which may limit widespread use. Moreover, since there may be an energy dependence, which manifests as a depth dependence, this may require additional measurements for each patient. We present a one-scan protocol to simplify the procedure. A calibration using an EBT3 film, exposed by a 6-level step-wedge plan on a Proteus®PLUS proton system (IBA, Belgium), was performed at depths of 18, 20, 24 cm using Plastic Water®(CIRS, Norfolk, VA). The calibration doses ranged from 65 - 250 cGy (RBE) (relative biological effectiveness) for proton energies of 170 - 200 MeV. A clinical prostate + nodes plan was used for validation. The planar doses at selected depths were measured with EBT3 films and analyzed using one-scan protocol (one-scan digitization of QA film and at least one film exposed to a known dose). The gamma passing rates, dose-difference maps, and profiles of 2D planar doses measured with EBT3 film and IBA MatriXX-PT, versus the RayStation TPS calculations were analyzed and compared. The EBT3 film measurement results matched well with the TPS calculation data with an average passing rate of ~95% for 2%/2 mm and slightly lower passing rates were obtained from an ion chamber array detector. We were able to demonstrate that the use of a proton step-wedge provided clinically acceptable results and minimized variations between film-scanner orientation, inter-scan, and scanning conditions. Furthermore, for relative dosimetry (calibration is not done at the time of experiment), it could be derived from no more than two films exposed to known doses (one could be zero) for rescaling the master calibration curve at each depth. The sensitivity of the calibration to depth variations has been explored. One-scan protocol results appear to be comparable to that of the ion chamber array detector. The use of a proton step-wedge for calibration of EBT3 film potentially increases efficiency in patient-specific QA of proton beams.
基金Funded by the Key Program Project of the National Natural Science Foundation of China (No.50234040)the Major Project of the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KCCX1-SW-22)
文摘The ultra-fine chromic oxide powder was prepared by a novel gas-solid reduction reaction.Na2CrO4 was firstly reduced with hydrogen at 400-600 ℃.The obtained reduction products,mainly the mixture of NaCrO2 and sodium hydroxide（NaOH）,were converted into chromic oxide through hydrolysis followed by calcination.The obtained chromic oxide product was characterized by powder X-ray diffraction（XRD） and SEM.The results show that the hydrolysis process of sodium chromite is the key step and lower reduction temperature helps intensify the hydrolysis process.
基金the National Natural Science Foundation of China (Nos. 21676113, 21402057, 21772054, 21472059)Distinguished Young Scholar of Hubei Province (No. 2018CFA079)+5 种基金Youth Chen-Guang Project of Wuhan (No. 2016070204010098) for the financial supportsupported by the 111 Project (No. B17019)the Ministry-Province Jointly Constructed Base for State Key Lab-Shenzhen Key Laboratory of Chemical Biology (Shenzhen), the State Key Laboratory of Materials-Oriented Chemical Engineering (No. KL17-10)Open Project Fund of Key Laboratory of Natural Resources of Changbai Mountain & Functional Molecules, Yanbian University (No. NRFM201701)Ministry of Education, the foundation of Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, Jiangnan University (No. JDSJ2017-07)self-determined research funds of CCNU from the colleges’ basic research and operation of MOE (No. CCNU18TS012)
文摘Organic chromic materials that respond to external stimuli, especially in the solid state, have sparked extensive interest owing to their potential use as smart materials. In particular, the availability of chromic materials, which emit fluorescence or phosphorescence in the deep penetrating, near-infrared（NIR）region, has led to great improvements in imaging. Various methods that were commonly applied to construct chromic materials, have been reformed to develop the novel type of compounds, and some have received rewards with excellent fingdings. Relevant research achievements of practical applications have showed their potential with the changes that locate in the NIR region, while further in-depth explorations about the inherent chromic chromism are underway. In this review, several representative studies, which have led the development of responsive organic chromic materials with near-infrared emission, will be discussed.
文摘This work presents the results of investigations to develop and implement methods to effectively collect and purify infiltrates from heaps, situated in the region of Alwernia near Cracow, where more than 3 million tonnes of waste material resulting from the production of chromium compounds have been stored. It describes a system for the protection of groundwater from these infiltrates which contain 50-400 g m-3 Cr6+, as well as the effectiveness of cheap and simple chemical methods to purify these chromic wastewaters. The infiltrate collection system and the most effective method to decrease the concentration of Cr6+ to a level below 0.1 ppm, as required by Polish and European Union regulations, were implemented in the Alwernia Chemical Works S. A. in the years 1998-1999.
基金supported by Hainan Provincial Natural Science Foundation of China(No.524MS027)the Scientific Research Support Project of Colleges and Universities in Hainan Province(No.Hnky2024-12)+3 种基金the Innovational Fund for Scientific and Technological Personnel of Hainan Province(No.KJRC2023D32)the Research Start-up Fund of Hainan University,China(No.KYQD(ZR)23039)the National Natural Science Foundation of China(No.22361017)the Innovation Platform for Academicians of Hainan Province,and the Specific Research Fund of the Innovation Platform for Academicians of Hainan Province(No.YSPTZX202321).
文摘Chromic materials with multi-stimuli responses have received tremendous attention from industry and academia for their potential applications in smart windows,data storage,military camouflage,molecular switches,modulators,etc.To develop multi-stimuli-responsive color-changing materials with high sensi-tivity and high stability,a polyoxometalate-based copper-viologen framework,formulated as Cu_(2)(H_(2)O)_(2)(L)_(2)[PW_(12)O_(40)][OH^(-)]·2H_(2)O(HNU-97,H_(2)L^(2+)=1,10-(1,4-phenylenebis(methylene))bis(4-carboxypyridinium)),was prepared by a mild one-step self-assembly strategy.Structural analysis shows that HNU-97 presents a supramolecular structure formed by a one-dimensional copper-viologen frame-work and polyoxometalates through rich hydrogen bonds,anion-πinteractions,etc.Discoloration studies show that HNU-97 exhibits reversible and rapid response characteristics to various external stimuli,such as 10 s to UV radiation,5 min to heating,and 5 min to ammonium/amine vapors.This mechanism re-veals that different external excitation sources lead to different preferential transfer directions of electrons,resulting in different discoloration phenomena.To construct stimuli-chromic materials with good mechanical properties,we successfully introduced HNU-97 into the poly(vinyl alcohol)(PVA)/glycerol(Gly)hydrogel to obtain a composite HNU-97@PVA/Gly.Remarkably,HNU-97@PVA/Gly combines the merits of each component and can achieve signifi-cant response discoloration behavior under both UV irradiation and ammonia atmosphere.This work will provide an idea for the construction of multiple stimuli-responsive materials.
文摘The reaction of Mg^(2+)and 5-{1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl}terephthalic acid(H_(2)L)leads to two metal-organic frameworks,[Mg(L)(DMF)_(2)(H_(2)O)_(2)]_(2)·5DMF·2H_(2)O(1)with a 1D structure and[Mg_(2)(L)_(2)(DMSO)_(3)(H_(2)O)](2)with a 2D(4,4)-net structure.Interestingly,the two compounds exhibit distinct luminescent responses to external mechanical stimuli.1 exhibited exceptional resistance mechanical chromic luminescence(RMCL),which can be attributed to the predominant hydrogen bonds and the presence of high-boiling-point solvent molecules within its structure.2 had a reversible MCL property,which can be attributed to the dominantπ-πweak interactions,coupled with the reversible destruction/restoration of its crystallinity under grinding/fumigation.CCDC:2410963,1;2410964,2.
