Ultra-fine Ce:YAG phosphors were prepared by homogeneous precipitation under microwave irradiation method. The formation of Ce:YAG was investigated by means of XRD and DTA/TG. The purified YAG crystallized phase was o...Ultra-fine Ce:YAG phosphors were prepared by homogeneous precipitation under microwave irradiation method. The formation of Ce:YAG was investigated by means of XRD and DTA/TG. The purified YAG crystallized phase was obtained at a lower temperature (1100 ℃). Basically spherical Ce:YAG powders were indicated from TEM images, and the size of the particles is about 80 nm. Two peaks of 436 and 473 nm can be seen from the excitation spectrum in the range of 402～510 nm. A broad emission band located at 480～630 nm shows the phosphors prepared by this method have good emission properties.展开更多
Fully-coupled thermo-mechanical simulations are implemented in COMSOL Multiphysics to investigate micro-scale stress-strain variability in pegmatite specimens subjected to thermal loading using microwaves. Thermally-i...Fully-coupled thermo-mechanical simulations are implemented in COMSOL Multiphysics to investigate micro-scale stress-strain variability in pegmatite specimens subjected to thermal loading using microwaves. Thermally-induced compressive and tensile stresses increase as the microwave irradiation duration increases. The dielectric constant, coefficient of expansion, and type and size of mineralogical boundary have significant impacts on the responses of the rock to microwave irradiation. The maximum principal stress of the chlorite is the smallest, indicating that the chlorite experiences the most damage under microwave irradiation, followed by the quartz. The maximum principal stress values of plagioclase and orthoclase are larger, indicating that they are likely to incur the least damage. Where quartz or chlorite is dominant, the resulting von Mises stresses are consistently higher after 120 s of microwave irradiation. The rate of generation of von Mises stresses increases most rapidly along the interface between quartz and plagioclase, and the interface between quartz and orthoclase, followed by the interface between quartz and chlorite, and finally the interface between plagioclase and orthoclase. The presented modeling approach provides a practical method to investigate stress-strain relationships within mineralogical boundaries inside a rock thin section.展开更多
A facile,rapid and efficient method for the synthesis of molecular tweezers containing chiral unsymmetrical urea unit in solvent- free conditions using microwave was reported.
A facile and efficient method for the preparation of 2-non-substituted quinoline-4-carboxylic acids is described via the Pfitzinger reaction of isatins with sodium pyruvate following consequent decarboxylation under m...A facile and efficient method for the preparation of 2-non-substituted quinoline-4-carboxylic acids is described via the Pfitzinger reaction of isatins with sodium pyruvate following consequent decarboxylation under microwave irradiation.展开更多
Biodegradable poly(epsilon-caprolactone-co-p-dioxanone)(PCDO) random copolymers have been synthesized by ring-opening polymerization of epsilon-caprolactone(CL) and p-dioxanone(PDO) under microwave irradiation.The eff...Biodegradable poly(epsilon-caprolactone-co-p-dioxanone)(PCDO) random copolymers have been synthesized by ring-opening polymerization of epsilon-caprolactone(CL) and p-dioxanone(PDO) under microwave irradiation.The effects of irradiation time and different CL/PDO molar feed ratios on the microwave-assisted ring-opening polymerization(MROP) of PCDO have been discussed.The resultant products were characterized by ~1H NMR,GPC and DSC.It was found that the polymerization was completed within 20 min at 140℃.In...展开更多
In this paper, the characteristics of the preparation of novolacs for the shell process under microwaveirradiation are investigated. Both polymerization and dehydration of the resins under microwave irradiation are co...In this paper, the characteristics of the preparation of novolacs for the shell process under microwaveirradiation are investigated. Both polymerization and dehydration of the resins under microwave irradiation are comparedwith those under conventional heating and further analysis is made. The results show that compared with those underconventional heating, the polymerization and dehydration time under microwave irradiation are shortened by 85.2% and80.7% respectively; On the other hand, the polymerization and dehydration under microwave irradiation lead to aremarkable increase in flow distance of the resins. Furthermore, the polymerization under microwave irradiation leads toreduced cure time, while the dehydration under microwave irradiation causes a slight increase in cure time.展开更多
Microwave irradiation can accelerate the rate of the synthetic reaction of α,β-unsaturated ketones by using KF-Al2O3 as catalyst. The rate enhancement of the reaction is 360-860 fold.
This study is a part of an overall research project on the effects of microwave(MW)irradiation on rocks for assisted rock breaking systems as well as mineral processing at McGill University.For the first time,this pap...This study is a part of an overall research project on the effects of microwave(MW)irradiation on rocks for assisted rock breaking systems as well as mineral processing at McGill University.For the first time,this paper highlights a comprehensive investigation on the effects of microwave irradiation on Canadian kimberlites.Potential contribution to the continuous rock excavation and rock weakening effect prior to implementation of mechanical techniques was explored.Two different kimberlite rocks,i.e.volcaniclastic kimberlite(VK)and hypabyssal kimberlite(HK),and granite samples were studied.Some important physical properties of the rock samples were measured including rock quality designation(RQD),specific gravity,porosity,and specific heat capacity.Rock samples were treated for various exposure times using a multi-mode MWunit at different power levels ranging from 2 kW to 15 kW.The effect of MW irradiation on rock samples was investigated.The results indicate that the mechanical properties including unconfined compressive strength(UCS)and Brazilian tensile strength(BTS)were significantly dropped as a result of MWirradiation.Finally,the effect on rock abrasivity using the Cerchar abrasivity index(CAI)has also been discussed.展开更多
Butylmethacrylate(BMA) was grafted onto woolen fabrics by microwave Irradiation In the presence of catalyst ((NH4) 4S2O8) .Various parameters of graft- copolyme-rlzation reaction, namely time of reaction, microwave in...Butylmethacrylate(BMA) was grafted onto woolen fabrics by microwave Irradiation In the presence of catalyst ((NH4) 4S2O8) .Various parameters of graft- copolyme-rlzation reaction, namely time of reaction, microwave intensity, catalyst and monomer concentration, were optimized . The graft - copolymerization was also compared with conventional heating graft- copolymerization at the same condition, it showed microwave irradiation could Improve the reactivity of the monomer. The moisture regain decreased as graft add - on increased, the strength of the grafted fabric decreased as graft add - on increased , but the strain increased hi some degree. The infrared spectrum showed an additional peak at 1700 cm-1, confirming ester carbonyl groups of the monomer.展开更多
The effects of oxidant dosage,oxidation temperature and time on the degradation of soda lignin by hydrogen peroxide with and without the presence of microwave irradiation were investigated.It is found that the oxidati...The effects of oxidant dosage,oxidation temperature and time on the degradation of soda lignin by hydrogen peroxide with and without the presence of microwave irradiation were investigated.It is found that the oxidative degradation of lignin includes the cleavage of ether bond inβ-O-4 structure,the partial destruction of aromatic ring,and the re-condensation of the degraded lignin.Compared to the conventionally heated oxidation of lignin,the microwave irradiation efficiently facilitates the degradation of the lignin with high molecular weight and the re-condensation of that with low molecular weight at a low oxidant dosage,low oxidation temperature,or a short oxidation time,which leads to the formation of the degraded lignin with narrower molecular weight distribution and lower molecular weight.Additionally,the lignin degraded in the presence of microwave irradiation has the characteristics of higher content of phenolic hydroxyl group,lower content of methoxyl group,and lower degree of condensation,which enhances the reactivity of lignin.Therefore,the oxidative degradation of lignin assisted by microwave irradiation may be a new pretreatment approach for efficiently utilizing the soda lignin.展开更多
A facile method of preparation of benzimidazoles by microwave irradiation was described. The mixtures of o-phenylenediamine and carboxylic acids were heated by microwave irradiation, to give 2-substituted benzimidazol...A facile method of preparation of benzimidazoles by microwave irradiation was described. The mixtures of o-phenylenediamine and carboxylic acids were heated by microwave irradiation, to give 2-substituted benzimidazoles with yields of 49%～93%. The reaction time was shortened to 3～6 min. However, the reaction of ethylenediamine with carboxylic acids did not give imidazoles but the N,N-diacyl ethylenediamines. The alphatic diamines lacked the activity to form imidazole ring. With adipic acid, intermolecular acylation took place to afford poly(ethylene adipamide).展开更多
A high yield xylanase producing strain, A. usamii L336-23, was screened out from its parent strain A.usamii L336 after microwave irradiation. Its productivity of xylanase activity increased by 35.7% from 21000μ·...A high yield xylanase producing strain, A. usamii L336-23, was screened out from its parent strain A.usamii L336 after microwave irradiation. Its productivity of xylanase activity increased by 35.7% from 21000μ·m1^-1 to 28500μ·m1^-1 and was stable after frequent subcultures and storage for more than two months.The mechanism of microwave mutation was also discussed.展开更多
Nano-TiO2 was employed for the separation and preconcentration of thallium.It was found that the adsorption ratio of thallium ions was more than 98% at pH 4.5 and the desorption ratio reached 99% under microwave irrad...Nano-TiO2 was employed for the separation and preconcentration of thallium.It was found that the adsorption ratio of thallium ions was more than 98% at pH 4.5 and the desorption ratio reached 99% under microwave irradiation for 3 min at 350 W.The adsorption equilibrium was well described by the Langmuir isotherm model with a maximum adsorption capacity of 4.09 mg/g[(20±0.1) °C].The nano-TiO2 was successfully applied to the determination of element thallium in the certified reference material polymetallic nodule and water samples.展开更多
The effect and mechanism of microwave irradiation on vanadium leaching were studied via a comparison between microwave heating and conventional heating. The results show a synergistic effect of microwave irradiation a...The effect and mechanism of microwave irradiation on vanadium leaching were studied via a comparison between microwave heating and conventional heating. The results show a synergistic effect of microwave irradiation and calcium fluoride(Ca F_2) on the vanadium leaching efficiency. It is confirmed that the vanadium leaching process can be improved by microwave irradiation when Ca F_2 is present. The leaching rate of vanadium under microwave irradiation is increased by 8%–15% when 5wt% Ca F_2 is added; by contrast,in the absence of Ca F_2,the leaching rate is almost unaffected compared to that by conventional heating. Morphological analysis reveals that the particles are gradually eroded by acid under microwave irradiation,whereas some of the fine particles in samples subjected to conventional heating are tightly covered by a flocculent silicate product. Moreover,a large amount of Al and V and a small amount of Si are dissolved from samples under microwave heating,as revealed by the elemental analysis of leachates. Fourier transform infrared spectroscopic analysis also indicates a higher mass transfer coefficient in the diffusion layer of the raw material by microwave irradiation. When Ca F_2 is present,the reaction energy barrier is lowered and the leaching process is controlled by the tightly covered product layer,resulting in a prominent effect of microwave irradiation.展开更多
The technique of microwave irradiation induced free radical bulk- polyaddition reactions in porous wood flour was used to modify wood flour. The behaviors of the modified wood flour under microwave irradiation, such a...The technique of microwave irradiation induced free radical bulk- polyaddition reactions in porous wood flour was used to modify wood flour. The behaviors of the modified wood flour under microwave irradiation, such as thermal stability and moisture sorption properties, were studied. A kind of semi- interpenetrating polymer network wood four (Semi-IPN-WF) can be formed through polymerization of MMA in the porous wood flour by microwave irradiation, and the thermal decomposition temperature of the semi-IPN- WF is considerably increased. PVC/Semi-IPN-WF composites were prepared by melt mixing in double rolls, which exhibit improved rheological properties, lower water sorption properties and outstanding mechanical performances.展开更多
A rapid and facile preparation of benzo-[b]-pyran derivatives through condensation of chalcone and 5, 5-dimethyl-1,3-cyclohexandione under microwave irradiation in the presence of catalytic amount of InCl3·4H2O h...A rapid and facile preparation of benzo-[b]-pyran derivatives through condensation of chalcone and 5, 5-dimethyl-1,3-cyclohexandione under microwave irradiation in the presence of catalytic amount of InCl3·4H2O has been developed. With its high efficiency, operational simplicity and environmental benignancy, this method may provide a useful alternative for the preparation of benzo-[b]-pyran derivatives.展开更多
基金Project supported by Foundation for the Excellent Middle-Aged or Young Scientists of Shandong Province (02BS049)
文摘Ultra-fine Ce:YAG phosphors were prepared by homogeneous precipitation under microwave irradiation method. The formation of Ce:YAG was investigated by means of XRD and DTA/TG. The purified YAG crystallized phase was obtained at a lower temperature (1100 ℃). Basically spherical Ce:YAG powders were indicated from TEM images, and the size of the particles is about 80 nm. Two peaks of 436 and 473 nm can be seen from the excitation spectrum in the range of 402～510 nm. A broad emission band located at 480～630 nm shows the phosphors prepared by this method have good emission properties.
基金supported by the US National Science Foundation (CMMI award 1550307)the China Scholarship Council for financial support as a visiting scholar at the Colorado School of Mines (Grant No. 201706375077)
文摘Fully-coupled thermo-mechanical simulations are implemented in COMSOL Multiphysics to investigate micro-scale stress-strain variability in pegmatite specimens subjected to thermal loading using microwaves. Thermally-induced compressive and tensile stresses increase as the microwave irradiation duration increases. The dielectric constant, coefficient of expansion, and type and size of mineralogical boundary have significant impacts on the responses of the rock to microwave irradiation. The maximum principal stress of the chlorite is the smallest, indicating that the chlorite experiences the most damage under microwave irradiation, followed by the quartz. The maximum principal stress values of plagioclase and orthoclase are larger, indicating that they are likely to incur the least damage. Where quartz or chlorite is dominant, the resulting von Mises stresses are consistently higher after 120 s of microwave irradiation. The rate of generation of von Mises stresses increases most rapidly along the interface between quartz and plagioclase, and the interface between quartz and orthoclase, followed by the interface between quartz and chlorite, and finally the interface between plagioclase and orthoclase. The presented modeling approach provides a practical method to investigate stress-strain relationships within mineralogical boundaries inside a rock thin section.
文摘A facile,rapid and efficient method for the synthesis of molecular tweezers containing chiral unsymmetrical urea unit in solvent- free conditions using microwave was reported.
基金the National Basic Research Program(No.2003CB515400),administered by the Ministry of Science and Technology of China.
文摘A facile and efficient method for the preparation of 2-non-substituted quinoline-4-carboxylic acids is described via the Pfitzinger reaction of isatins with sodium pyruvate following consequent decarboxylation under microwave irradiation.
文摘Biodegradable poly(epsilon-caprolactone-co-p-dioxanone)(PCDO) random copolymers have been synthesized by ring-opening polymerization of epsilon-caprolactone(CL) and p-dioxanone(PDO) under microwave irradiation.The effects of irradiation time and different CL/PDO molar feed ratios on the microwave-assisted ring-opening polymerization(MROP) of PCDO have been discussed.The resultant products were characterized by ~1H NMR,GPC and DSC.It was found that the polymerization was completed within 20 min at 140℃.In...
文摘In this paper, the characteristics of the preparation of novolacs for the shell process under microwaveirradiation are investigated. Both polymerization and dehydration of the resins under microwave irradiation are comparedwith those under conventional heating and further analysis is made. The results show that compared with those underconventional heating, the polymerization and dehydration time under microwave irradiation are shortened by 85.2% and80.7% respectively; On the other hand, the polymerization and dehydration under microwave irradiation lead to aremarkable increase in flow distance of the resins. Furthermore, the polymerization under microwave irradiation leads toreduced cure time, while the dehydration under microwave irradiation causes a slight increase in cure time.
文摘Microwave irradiation can accelerate the rate of the synthetic reaction of α,β-unsaturated ketones by using KF-Al2O3 as catalyst. The rate enhancement of the reaction is 360-860 fold.
基金The financial support from the Natural Sciences and Engineering Research Council of Canada(NSERC)and our industrial partners,DeBeers,Metso,and Argex companies as well as PhD scholarship to Mr.Samir Deyab from the department of mining engineering,Tripoli University are gratefully acknowledged.
文摘This study is a part of an overall research project on the effects of microwave(MW)irradiation on rocks for assisted rock breaking systems as well as mineral processing at McGill University.For the first time,this paper highlights a comprehensive investigation on the effects of microwave irradiation on Canadian kimberlites.Potential contribution to the continuous rock excavation and rock weakening effect prior to implementation of mechanical techniques was explored.Two different kimberlite rocks,i.e.volcaniclastic kimberlite(VK)and hypabyssal kimberlite(HK),and granite samples were studied.Some important physical properties of the rock samples were measured including rock quality designation(RQD),specific gravity,porosity,and specific heat capacity.Rock samples were treated for various exposure times using a multi-mode MWunit at different power levels ranging from 2 kW to 15 kW.The effect of MW irradiation on rock samples was investigated.The results indicate that the mechanical properties including unconfined compressive strength(UCS)and Brazilian tensile strength(BTS)were significantly dropped as a result of MWirradiation.Finally,the effect on rock abrasivity using the Cerchar abrasivity index(CAI)has also been discussed.
文摘Butylmethacrylate(BMA) was grafted onto woolen fabrics by microwave Irradiation In the presence of catalyst ((NH4) 4S2O8) .Various parameters of graft- copolyme-rlzation reaction, namely time of reaction, microwave intensity, catalyst and monomer concentration, were optimized . The graft - copolymerization was also compared with conventional heating graft- copolymerization at the same condition, it showed microwave irradiation could Improve the reactivity of the monomer. The moisture regain decreased as graft add - on increased, the strength of the grafted fabric decreased as graft add - on increased , but the strain increased hi some degree. The infrared spectrum showed an additional peak at 1700 cm-1, confirming ester carbonyl groups of the monomer.
基金Supported by the National Natural Science Foundation of China（20876064） the Natural Science Foundation of Guangdong Province（9151064101000082） the Guangdong Provincial International Cooperation Fund（2008B05010006）
文摘The effects of oxidant dosage,oxidation temperature and time on the degradation of soda lignin by hydrogen peroxide with and without the presence of microwave irradiation were investigated.It is found that the oxidative degradation of lignin includes the cleavage of ether bond inβ-O-4 structure,the partial destruction of aromatic ring,and the re-condensation of the degraded lignin.Compared to the conventionally heated oxidation of lignin,the microwave irradiation efficiently facilitates the degradation of the lignin with high molecular weight and the re-condensation of that with low molecular weight at a low oxidant dosage,low oxidation temperature,or a short oxidation time,which leads to the formation of the degraded lignin with narrower molecular weight distribution and lower molecular weight.Additionally,the lignin degraded in the presence of microwave irradiation has the characteristics of higher content of phenolic hydroxyl group,lower content of methoxyl group,and lower degree of condensation,which enhances the reactivity of lignin.Therefore,the oxidative degradation of lignin assisted by microwave irradiation may be a new pretreatment approach for efficiently utilizing the soda lignin.
文摘A facile method of preparation of benzimidazoles by microwave irradiation was described. The mixtures of o-phenylenediamine and carboxylic acids were heated by microwave irradiation, to give 2-substituted benzimidazoles with yields of 49%～93%. The reaction time was shortened to 3～6 min. However, the reaction of ethylenediamine with carboxylic acids did not give imidazoles but the N,N-diacyl ethylenediamines. The alphatic diamines lacked the activity to form imidazole ring. With adipic acid, intermolecular acylation took place to afford poly(ethylene adipamide).
基金Natural Science Foundation of Zhejiang Province(No.395186)
文摘A high yield xylanase producing strain, A. usamii L336-23, was screened out from its parent strain A.usamii L336 after microwave irradiation. Its productivity of xylanase activity increased by 35.7% from 21000μ·m1^-1 to 28500μ·m1^-1 and was stable after frequent subcultures and storage for more than two months.The mechanism of microwave mutation was also discussed.
基金Supported by the Excellent Talents Project(No.2009R30)Innovation Team Project(No.2007T053)of the Education Department of Liaoning Province,China
文摘Nano-TiO2 was employed for the separation and preconcentration of thallium.It was found that the adsorption ratio of thallium ions was more than 98% at pH 4.5 and the desorption ratio reached 99% under microwave irradiation for 3 min at 350 W.The adsorption equilibrium was well described by the Langmuir isotherm model with a maximum adsorption capacity of 4.09 mg/g[(20±0.1) °C].The nano-TiO2 was successfully applied to the determination of element thallium in the certified reference material polymetallic nodule and water samples.
基金financially supported by the National Natural Science Foundation of China(Nos.51474162 and 51404174)the Research Project of the Ministry of Education of China(No.213025A)
文摘The effect and mechanism of microwave irradiation on vanadium leaching were studied via a comparison between microwave heating and conventional heating. The results show a synergistic effect of microwave irradiation and calcium fluoride(Ca F_2) on the vanadium leaching efficiency. It is confirmed that the vanadium leaching process can be improved by microwave irradiation when Ca F_2 is present. The leaching rate of vanadium under microwave irradiation is increased by 8%–15% when 5wt% Ca F_2 is added; by contrast,in the absence of Ca F_2,the leaching rate is almost unaffected compared to that by conventional heating. Morphological analysis reveals that the particles are gradually eroded by acid under microwave irradiation,whereas some of the fine particles in samples subjected to conventional heating are tightly covered by a flocculent silicate product. Moreover,a large amount of Al and V and a small amount of Si are dissolved from samples under microwave heating,as revealed by the elemental analysis of leachates. Fourier transform infrared spectroscopic analysis also indicates a higher mass transfer coefficient in the diffusion layer of the raw material by microwave irradiation. When Ca F_2 is present,the reaction energy barrier is lowered and the leaching process is controlled by the tightly covered product layer,resulting in a prominent effect of microwave irradiation.
基金Funded by the Natural Science Foundation of Hubei Province (No. 2003ABA084)
文摘The technique of microwave irradiation induced free radical bulk- polyaddition reactions in porous wood flour was used to modify wood flour. The behaviors of the modified wood flour under microwave irradiation, such as thermal stability and moisture sorption properties, were studied. A kind of semi- interpenetrating polymer network wood four (Semi-IPN-WF) can be formed through polymerization of MMA in the porous wood flour by microwave irradiation, and the thermal decomposition temperature of the semi-IPN- WF is considerably increased. PVC/Semi-IPN-WF composites were prepared by melt mixing in double rolls, which exhibit improved rheological properties, lower water sorption properties and outstanding mechanical performances.
基金This work was financially supported by the National Natural Science Foundation of China(No.20372018)the Science Foundation of Henan Normal University for Young Scholars(No.0307032).
文摘A rapid and facile preparation of benzo-[b]-pyran derivatives through condensation of chalcone and 5, 5-dimethyl-1,3-cyclohexandione under microwave irradiation in the presence of catalytic amount of InCl3·4H2O has been developed. With its high efficiency, operational simplicity and environmental benignancy, this method may provide a useful alternative for the preparation of benzo-[b]-pyran derivatives.
