Optical clocks with thermal atoms are characterized by compact size,simple structure,reduced weight,and low power consumption and have the potential for broad out-of-the-lab and commercial applications.Here,we demonst...Optical clocks with thermal atoms are characterized by compact size,simple structure,reduced weight,and low power consumption and have the potential for broad out-of-the-lab and commercial applications.Here,we demonstrate a 459 nm optical clock based on the 6S_(1/2)-7P_(1/2)transition in thermal^(133)Cs atoms.Two methods,modulation transfer spectroscopy(MTS)and frequency modulation spectroscopy(FMS),are employed to stabilize the frequency of a 459 nm commercial laser to the atomic transition.The MTS-MTS and MTS-FMS beat-note measurements show short-term frequency stabilities of 3.7×10^(-13)/√t and 6.4×10^(-13)/√t,respectively,at the averaging time t.The 459 nm passive optical clock further serves as the pump for an active 1470 nm optical clock based on the cavityless lasing.The resultant 1470 nm output power reaches over 10μW and the pump-beam-induced light shift is estimated to be 2π×11 Hz with a fractional uncertainty of 2.4×10^(-18).These results demonstrate the feasibility of hybridizing passive and active optical clocks,providing a promising route toward compact multi-wavelength optical frequency standards.展开更多
Shape Memory Alloy (SMA) optically activated is the key technology of optical SMA activator.According to the shape memory mechanism of SMA,researches are done on the activating response time and light wavelength of ac...Shape Memory Alloy (SMA) optically activated is the key technology of optical SMA activator.According to the shape memory mechanism of SMA,researches are done on the activating response time and light wavelength of activating source etc of SMA optically activated to approach the parameters selection of optical activation.SMA has the optimum efficiency in the range of 13 seconds to 27 seconds when SMA is illuminated continuously by wavelength of 675nm;The power of light wave has a low effect on SMA;The longer the activating wavelength,the quicker the response time of SMA activated.If the proper activating time and activating wavelength are adopted, and the structure deformation of composite material of SMA imbedded may be actively controlled,an ideal effect will be gotten.The research provides an evidence for the design of optical SMA activator and is of great significance to its application.The research on smart structure has a wide application prospect.展开更多
A model for theoretical analysis of nonlinear (or high gain) mode of photoconductive semiconductor switches (PCSS's) is proposed.The switching transition of high gain PCSS's can be described with an optically...A model for theoretical analysis of nonlinear (or high gain) mode of photoconductive semiconductor switches (PCSS's) is proposed.The switching transition of high gain PCSS's can be described with an optically activated charge domain. The switching characteristics including rise time,delay and their relationship to electric field strength,optical trigger energies are discussed.The formation and radiation transit,accumulation of the charge domain are related with the triggering and sustaining phases of PCSS's,respectively.The results of the mathematical model on this mechanism agree with experimental results.展开更多
Five new optically active polyamides （PAs） 6a-6e were prepared by direct polycondensation reaction of 2-（1,3- isoindolinedione-2-yl）-glutaric acid 4 as a new chiral diacid with various aromatic diamines 5a-Se in a...Five new optically active polyamides （PAs） 6a-6e were prepared by direct polycondensation reaction of 2-（1,3- isoindolinedione-2-yl）-glutaric acid 4 as a new chiral diacid with various aromatic diamines 5a-Se in a medium consisting of triphenyl phosphite （TPP）, calcium chloride, pyridine （Py） and N-methyl-2-pyrrolidone （NMP）. The polycondensation reaction produced a series of polyamids 6a-6e in quantitative yields with inherent viscosities of 0.26-0.39 dL/g. The resulting polymers were fully characterized by means of ^1H-NMR, FT-1R spectroscopy, elemental analysis, inherent viscosity and specific rotation. Thermal properties of these polymers were investigated using thermal gravimetric analysis （TGA） and differential thermal gravimetry （DTG）. Phthalimide rings as a bulky pendent group in the polymer chains disturb the interchain and intrachain interactions and make these PAs readily soluble in polar, aprotic solvents such as N,N-dimethyl acetamide （DMAc）, N,N-dimethyl formamide （DMF）, dimethyl sulfoxide （DMSO）, N-methyl-2-pyrrolidone （NMP） and sulfuric acid.展开更多
A series of new optically active poly（amide-imide）s were synthesized by direct polycondensation reaction of 4,4＇-diaminochalcone with several N-trimellitylimido-L-amino acids using a tosyl chloride （TsCl）, pyridi...A series of new optically active poly（amide-imide）s were synthesized by direct polycondensation reaction of 4,4＇-diaminochalcone with several N-trimellitylimido-L-amino acids using a tosyl chloride （TsCl）, pyridine （Py） and dimethylformamide （DMF） system as condensing agent. The resulting thermally stable poly（amide-imide）s were obtained in good to high yields and inherent viscosities ranging between 0.35 dL/g and 0.58 dL/g and were characterized with FTIR, IH-NMR, CHN, Ultraviolet, TGA and DTG techniques.展开更多
We experimentally realize the dual-wavelength bad cavity laser for the first time. As the Cs cell temperature is kept between 118℃ and 144℃, both the 1359nm and 147Ohm lasing outputs of dual-wavelength bad cavity la...We experimentally realize the dual-wavelength bad cavity laser for the first time. As the Cs cell temperature is kept between 118℃ and 144℃, both the 1359nm and 147Ohm lasing outputs of dual-wavelength bad cavity laser are detected. The laser output power of dual-wavelength bad cavity laser is measured when changing the 455 nm pumping laser frequency and power at 127℃ Cs cell temperature. Both the 1359 nm laser and the 1470 nm laser are working at the deep bad cavity regime, and the ratio between the linewidth of cavity mode and the laser gain bandwidth a ≈ 40 for 1359nm and 1470nm lasers. The 147Ohm laser linewidth is measured to be 407.3Hz. The dual-wavelength bad cavity laser operating on atomic transitions demonstrated here has a potential in the application as a stable optical local oscillator, even an active optical frequency standard directly in the future.展开更多
A novel calix[4]arene derivative 2 with amino functional groups at the lower rim was first prepared via introduction of nitro functional groups and amination of the dinitro derivative of calix[4]arene. The optically a...A novel calix[4]arene derivative 2 with amino functional groups at the lower rim was first prepared via introduction of nitro functional groups and amination of the dinitro derivative of calix[4]arene. The optically active monomers were synthesized by dehydration of L-leucine （and L-isoleucine） and 3,3＇,4,4＇-benzophenonetetracarboxylic- 3,3＇,4,4＇-dianhydride （3） followed by reaction with thionyl chloride to form 5a and 5b. Two methods, polymerization under microwave irradiation and solution polymerization in CH2Cl2/TEA, were then employed to carry out the condensation polymerization of 2 with the optically active monomers 5a and 5b, respectively. The polymerization conditions affected the kind of resulting polymers, poly（amide-imide）s （PAIs） 6a and 6b and poly（ester-imide）s （PEIs） 6a＇ and 6b＇ were obtained selectively in good yields and moderate inherent viscosities. Sorption-extraction experiments were carried out using cram picrate extraction method and verified good binding ability of the resulting calixarene-based polymers towards silver, alkali metal and toxic heavy metal cations. Also thermogravimetric analysis indicated that the resulting PAIs and PEIs were thermally stable.展开更多
An optically active bulky aromatic diacid chiral monomer, （2S）-4-[（4-methyl-2-phthalimidylpentanoylamino）benzoylamino]isophthalic acid （1）, containing a rigid phthalimide and flexible L-leucine pendent group was...An optically active bulky aromatic diacid chiral monomer, （2S）-4-[（4-methyl-2-phthalimidylpentanoylamino）benzoylamino]isophthalic acid （1）, containing a rigid phthalimide and flexible L-leucine pendent group was synthesized in five steps. A fast and clean method for direct polyamidation reaction of monomer 1 with various aromatic diamines under microwave irradiation and conventional heating was performed. The polymerization reactions provided optically active polyamides with high yields and inherent viscosities in the range of 0.36-0.74 dL/g. Their thermal properties were evaluated by thermogravimetric analysis （TGA） and differential scanning calorimetry. TGA thermograms show that the polymers are thermally stable, 10% weight loss temperatures are in excess of 385℃, and char yields at 800℃ are higher than 56%. The data obtained from TGA were used to study the kinetics of thermal decomposition of the resulting polymers. The interpretation of kinetic parameters （E, AH, AS and AG） of thermal decomposition stages was evaluated using Coats and Redfern equation.展开更多
L-Lysine hydrochloride was transformed to ethyl L-lysine dihydrochloride.This salt was reacted with trimellitic anhydride to yield the corresponding diacid（1）.Intertacial polycondensation results novel poly（ester-i...L-Lysine hydrochloride was transformed to ethyl L-lysine dihydrochloride.This salt was reacted with trimellitic anhydride to yield the corresponding diacid（1）.Intertacial polycondensation results novel poly（ester-imide）s（PEI_（a-i））.These polymers have inherent viscosities in the range of 0.23-0.47 dl g^（-1）,display optical activity,and are readily soluble in polar aprotic solvents.They start to decompose（T_（10%）） above 350℃and display glass-transition temperatures at 100.42-172.81℃.All of the above polymers were fully characterized by UV,FT-IR and ~1H NMR spectroscopy,elemental analysis,TGA,DSC,inherent viscosity measurement and specific rotation.展开更多
Six new optically active and flame-retardant poly（amide-imide）s PAls 5a-5f containing phosphine oxide moiety as a flame-retardant unit in the main chain were synthesized from direct polycondensation reaction of six ...Six new optically active and flame-retardant poly（amide-imide）s PAls 5a-5f containing phosphine oxide moiety as a flame-retardant unit in the main chain were synthesized from direct polycondensation reaction of six chiral N,N＇-（pyromellitoyl）-bis-L-amino acid 3a-3f with bis（3-aminophenyl）phenyl phosphine oxide 4 in a medium consisting of N-methyl-2-pyrrolidone （NMP）, triphenyl phosphite （TPP）, calcium chloride （CaCl2） and pyridine. The polymerization reactions produced a series of optically active poly（amide-imide）s with good yield and good inherent viscosity of 0.34-0.70 dLg^-1. The resulted polymers were fully characterized by means of FTIR and ^1H-NMR spectroscopy, gel permeation chromatography （GPC）, elemental analyses, inherent viscosity and solubility tests. Thermal properties and flameretardant behavior of the PAIs 5a-5f were investigated using thermal gravimetric analysis （TGA and DTG） and limiting oxygen index （LOI）. Data obtained by thermal analysis （TGA and DTG） revealed that these polymers showed good thermal stability. Furthermore, high char yield in TGA and good LOI values indicated that the resulting polymers were capable of exhibiting good flame retardant properties. N,N＇-（pyromellitoyl）-bis-L-amino acids 3a-3f were prepared in quantitative yields by the condensation reaction of pyromellitic dianhydride （1,2,4,5-benzenetetracarboxylicacid-1,2,4,5-dianhydride） 1 with L-alanine 2a, L-valine 2b, L-leucine 2c, L-isoleucine 2d, L-phenyl alanine 2e and L-2-aminobutyric acid 2f in acetic acid solution.展开更多
The experimental scheme of 633 nm and 1359 nm good-bad cavity dual-wavelength active optical frequency stan- dard is proposed, where He-Ne 633nm and Cs 1359nm stimulated emissions are working at good-cavity and bad-ca...The experimental scheme of 633 nm and 1359 nm good-bad cavity dual-wavelength active optical frequency stan- dard is proposed, where He-Ne 633nm and Cs 1359nm stimulated emissions are working at good-cavity and bad-cavity regimes, respectively. The cavity length is stabilized by locking the 633nm output frequency to a super-cavity with the Pound Drever-Hall （PDH） technique. The frequency stability of 1359 nm bad-cavity stim- ulated emission output is then expected to be further improved by at least 1 order of magnitude than the 633nm PDH system due to the suppressed cavity pulling effect of active optical clock, and the quantum limited linewidth of 1359nm output is estimated to be 72.5 mHz.展开更多
With sol-gel method,nanometer La-Ti composite oxides were prepared.By means of atomic force microscope,the surface pattern,particle size distribution and specific surface area were studied.The newly prepared nanocryst...With sol-gel method,nanometer La-Ti composite oxides were prepared.By means of atomic force microscope,the surface pattern,particle size distribution and specific surface area were studied.The newly prepared nanocrystals of La-Ti composite oxides were used as the catalysts to catalyze the dehydration of external compensated lactic acid to lactide.The lactide product was measured by polarimeter and micropolariscope.The results demonstrate that the ratio between D-lactide and L-lactide will not be equal to 1-1 if nanocrystals of La-Ti composite oxides are used as the catalysts,which implies,that nanocrystals of La-Ti composite oxides may be potential catalysts with a good selectivity.展开更多
Optically active (R)-(+)-2, 2' -bis(2 -trifluoro-4 -aminophenoxy)- 1, 1' -binaphthyl was prepared from1, 1'-bi-2-naphthol. The optically active aromatic polyimide was also successfully synthesized. This ne...Optically active (R)-(+)-2, 2' -bis(2 -trifluoro-4 -aminophenoxy)- 1, 1' -binaphthyl was prepared from1, 1'-bi-2-naphthol. The optically active aromatic polyimide was also successfully synthesized. This newpolymer has good solubility, thermal stability etc. Its specific rotation was found to be +174°, and itschiroptical property was also studied.展开更多
Just like an electronic diode that allows the electrical current to flow in one direction only, a kind of chiral metamaterial structure with a similar functionality for the electromagnetic wave is proposed. The design...Just like an electronic diode that allows the electrical current to flow in one direction only, a kind of chiral metamaterial structure with a similar functionality for the electromagnetic wave is proposed. The designed nanostructure that consists of twisted metallic split-ring resonators on both sides of a dielectric substrate achieves asymmetric transmission for a forward and backward propagating linearly polarized wave by numerical simulation in near-infrared band. Difference in transmission efficiency of the optimized structure between the same polarized waves incident from opposite directions can reach a maximum at the communication wavelength （1.55 μm）. Moreover, the simulation results of this structure also exhibit strong optical activity and circular dichroism.展开更多
A new kind of hydrazone (I) diastereoisomers was prepared with enantiomeric hydazide (II) and chiral cluster (III), which was characterized by HMBC. Unfortunately, the mixture could not be separated into pure diastere...A new kind of hydrazone (I) diastereoisomers was prepared with enantiomeric hydazide (II) and chiral cluster (III), which was characterized by HMBC. Unfortunately, the mixture could not be separated into pure diastereoisomer. This could be a direction to separate the racemic chiral clusters.展开更多
Isatoic anhydride was reacted with several L-amino acids to give the corresponding （2S）-N-（o-aminobenzoyl）-2-alkylaminoacetic acids. The latter compounds were treated with phosphoryl chloride under reflux temperat...Isatoic anhydride was reacted with several L-amino acids to give the corresponding （2S）-N-（o-aminobenzoyl）-2-alkylaminoacetic acids. The latter compounds were treated with phosphoryl chloride under reflux temperature to afford the cyclized products, （3S）-3-alkyl-3,4-dihydro- 1 H- 1,4-benzodiazepin-2,5-diones. 2007 M. Bakavoli. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
The organic salts as initiators [A*B-+(-):Ph*3C+ClO4-, Ph(3)*C+SbCl6-, (-)Sp*(ClO4-)-Cl-+ and (-)(Sp)(2)*(+3)(ClO4-)(3)] and catalysts [A(+)B*(-):(+)CSA*, A*B-+*(-):Ph(3)*C+(+)CSA*(-) and (-)Sp*(+)(+)CSA*] are prepare...The organic salts as initiators [A*B-+(-):Ph*3C+ClO4-, Ph(3)*C+SbCl6-, (-)Sp*(ClO4-)-Cl-+ and (-)(Sp)(2)*(+3)(ClO4-)(3)] and catalysts [A(+)B*(-):(+)CSA*, A*B-+*(-):Ph(3)*C+(+)CSA*(-) and (-)Sp*(+)(+)CSA*] are prepared and characterized by specific rotation. The asymmetrically stereoselective induction of the initiators and catalysts in thc polymerization of N-vinylcarbazole is in an order of A*B-+*(-) > A(+)B*(-) > A*B-+(-). The specific rotations of obtained poly(N-vinylcarbazole) (PVCZ) generally are in accordance with mentioned order.展开更多
基金provided by CAS Project for Young Scientists in Basic Research(Grant No.YSBR-085)National Time Service Center(Grant No.E239SC1101)+1 种基金the funding of Wenzhou Major Science&Technology Innovation Key Project(Grant No.ZG2023021)supported by Innovation Program for Quantum Science and Technology(Grant No.2021ZD0303200).
文摘Optical clocks with thermal atoms are characterized by compact size,simple structure,reduced weight,and low power consumption and have the potential for broad out-of-the-lab and commercial applications.Here,we demonstrate a 459 nm optical clock based on the 6S_(1/2)-7P_(1/2)transition in thermal^(133)Cs atoms.Two methods,modulation transfer spectroscopy(MTS)and frequency modulation spectroscopy(FMS),are employed to stabilize the frequency of a 459 nm commercial laser to the atomic transition.The MTS-MTS and MTS-FMS beat-note measurements show short-term frequency stabilities of 3.7×10^(-13)/√t and 6.4×10^(-13)/√t,respectively,at the averaging time t.The 459 nm passive optical clock further serves as the pump for an active 1470 nm optical clock based on the cavityless lasing.The resultant 1470 nm output power reaches over 10μW and the pump-beam-induced light shift is estimated to be 2π×11 Hz with a fractional uncertainty of 2.4×10^(-18).These results demonstrate the feasibility of hybridizing passive and active optical clocks,providing a promising route toward compact multi-wavelength optical frequency standards.
文摘Shape Memory Alloy (SMA) optically activated is the key technology of optical SMA activator.According to the shape memory mechanism of SMA,researches are done on the activating response time and light wavelength of activating source etc of SMA optically activated to approach the parameters selection of optical activation.SMA has the optimum efficiency in the range of 13 seconds to 27 seconds when SMA is illuminated continuously by wavelength of 675nm;The power of light wave has a low effect on SMA;The longer the activating wavelength,the quicker the response time of SMA activated.If the proper activating time and activating wavelength are adopted, and the structure deformation of composite material of SMA imbedded may be actively controlled,an ideal effect will be gotten.The research provides an evidence for the design of optical SMA activator and is of great significance to its application.The research on smart structure has a wide application prospect.
文摘A model for theoretical analysis of nonlinear (or high gain) mode of photoconductive semiconductor switches (PCSS's) is proposed.The switching transition of high gain PCSS's can be described with an optically activated charge domain. The switching characteristics including rise time,delay and their relationship to electric field strength,optical trigger energies are discussed.The formation and radiation transit,accumulation of the charge domain are related with the triggering and sustaining phases of PCSS's,respectively.The results of the mathematical model on this mechanism agree with experimental results.
文摘Five new optically active polyamides （PAs） 6a-6e were prepared by direct polycondensation reaction of 2-（1,3- isoindolinedione-2-yl）-glutaric acid 4 as a new chiral diacid with various aromatic diamines 5a-Se in a medium consisting of triphenyl phosphite （TPP）, calcium chloride, pyridine （Py） and N-methyl-2-pyrrolidone （NMP）. The polycondensation reaction produced a series of polyamids 6a-6e in quantitative yields with inherent viscosities of 0.26-0.39 dL/g. The resulting polymers were fully characterized by means of ^1H-NMR, FT-1R spectroscopy, elemental analysis, inherent viscosity and specific rotation. Thermal properties of these polymers were investigated using thermal gravimetric analysis （TGA） and differential thermal gravimetry （DTG）. Phthalimide rings as a bulky pendent group in the polymer chains disturb the interchain and intrachain interactions and make these PAs readily soluble in polar, aprotic solvents such as N,N-dimethyl acetamide （DMAc）, N,N-dimethyl formamide （DMF）, dimethyl sulfoxide （DMSO）, N-methyl-2-pyrrolidone （NMP） and sulfuric acid.
文摘A series of new optically active poly（amide-imide）s were synthesized by direct polycondensation reaction of 4,4＇-diaminochalcone with several N-trimellitylimido-L-amino acids using a tosyl chloride （TsCl）, pyridine （Py） and dimethylformamide （DMF） system as condensing agent. The resulting thermally stable poly（amide-imide）s were obtained in good to high yields and inherent viscosities ranging between 0.35 dL/g and 0.58 dL/g and were characterized with FTIR, IH-NMR, CHN, Ultraviolet, TGA and DTG techniques.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10874009,11074011 and 91436210the International Science and Technology Cooperation Program of China under Grant No 2010DFR10900
文摘We experimentally realize the dual-wavelength bad cavity laser for the first time. As the Cs cell temperature is kept between 118℃ and 144℃, both the 1359nm and 147Ohm lasing outputs of dual-wavelength bad cavity laser are detected. The laser output power of dual-wavelength bad cavity laser is measured when changing the 455 nm pumping laser frequency and power at 127℃ Cs cell temperature. Both the 1359 nm laser and the 1470 nm laser are working at the deep bad cavity regime, and the ratio between the linewidth of cavity mode and the laser gain bandwidth a ≈ 40 for 1359nm and 1470nm lasers. The 147Ohm laser linewidth is measured to be 407.3Hz. The dual-wavelength bad cavity laser operating on atomic transitions demonstrated here has a potential in the application as a stable optical local oscillator, even an active optical frequency standard directly in the future.
基金supported by the Isfahan University of Technology(IUT),IR Iran(ARH) and grant GM 33138 (AER) from the national Institute of health,USA and center of Excellency in chemistry research(IUT).
文摘A novel calix[4]arene derivative 2 with amino functional groups at the lower rim was first prepared via introduction of nitro functional groups and amination of the dinitro derivative of calix[4]arene. The optically active monomers were synthesized by dehydration of L-leucine （and L-isoleucine） and 3,3＇,4,4＇-benzophenonetetracarboxylic- 3,3＇,4,4＇-dianhydride （3） followed by reaction with thionyl chloride to form 5a and 5b. Two methods, polymerization under microwave irradiation and solution polymerization in CH2Cl2/TEA, were then employed to carry out the condensation polymerization of 2 with the optically active monomers 5a and 5b, respectively. The polymerization conditions affected the kind of resulting polymers, poly（amide-imide）s （PAIs） 6a and 6b and poly（ester-imide）s （PEIs） 6a＇ and 6b＇ were obtained selectively in good yields and moderate inherent viscosities. Sorption-extraction experiments were carried out using cram picrate extraction method and verified good binding ability of the resulting calixarene-based polymers towards silver, alkali metal and toxic heavy metal cations. Also thermogravimetric analysis indicated that the resulting PAIs and PEIs were thermally stable.
基金supported by the Research Affairs Division Isfahan University of Technology(IUT),IsfahanNational Elite Foundation(NEF) and Center of Excellency in Sensors and Green Chemistry Research(IUT).
文摘An optically active bulky aromatic diacid chiral monomer, （2S）-4-[（4-methyl-2-phthalimidylpentanoylamino）benzoylamino]isophthalic acid （1）, containing a rigid phthalimide and flexible L-leucine pendent group was synthesized in five steps. A fast and clean method for direct polyamidation reaction of monomer 1 with various aromatic diamines under microwave irradiation and conventional heating was performed. The polymerization reactions provided optically active polyamides with high yields and inherent viscosities in the range of 0.36-0.74 dL/g. Their thermal properties were evaluated by thermogravimetric analysis （TGA） and differential scanning calorimetry. TGA thermograms show that the polymers are thermally stable, 10% weight loss temperatures are in excess of 385℃, and char yields at 800℃ are higher than 56%. The data obtained from TGA were used to study the kinetics of thermal decomposition of the resulting polymers. The interpretation of kinetic parameters （E, AH, AS and AG） of thermal decomposition stages was evaluated using Coats and Redfern equation.
基金the funding support received fot this project from Firouzabad Islamic Azad University
文摘L-Lysine hydrochloride was transformed to ethyl L-lysine dihydrochloride.This salt was reacted with trimellitic anhydride to yield the corresponding diacid（1）.Intertacial polycondensation results novel poly（ester-imide）s（PEI_（a-i））.These polymers have inherent viscosities in the range of 0.23-0.47 dl g^（-1）,display optical activity,and are readily soluble in polar aprotic solvents.They start to decompose（T_（10%）） above 350℃and display glass-transition temperatures at 100.42-172.81℃.All of the above polymers were fully characterized by UV,FT-IR and ~1H NMR spectroscopy,elemental analysis,TGA,DSC,inherent viscosity measurement and specific rotation.
文摘Six new optically active and flame-retardant poly（amide-imide）s PAls 5a-5f containing phosphine oxide moiety as a flame-retardant unit in the main chain were synthesized from direct polycondensation reaction of six chiral N,N＇-（pyromellitoyl）-bis-L-amino acid 3a-3f with bis（3-aminophenyl）phenyl phosphine oxide 4 in a medium consisting of N-methyl-2-pyrrolidone （NMP）, triphenyl phosphite （TPP）, calcium chloride （CaCl2） and pyridine. The polymerization reactions produced a series of optically active poly（amide-imide）s with good yield and good inherent viscosity of 0.34-0.70 dLg^-1. The resulted polymers were fully characterized by means of FTIR and ^1H-NMR spectroscopy, gel permeation chromatography （GPC）, elemental analyses, inherent viscosity and solubility tests. Thermal properties and flameretardant behavior of the PAIs 5a-5f were investigated using thermal gravimetric analysis （TGA and DTG） and limiting oxygen index （LOI）. Data obtained by thermal analysis （TGA and DTG） revealed that these polymers showed good thermal stability. Furthermore, high char yield in TGA and good LOI values indicated that the resulting polymers were capable of exhibiting good flame retardant properties. N,N＇-（pyromellitoyl）-bis-L-amino acids 3a-3f were prepared in quantitative yields by the condensation reaction of pyromellitic dianhydride （1,2,4,5-benzenetetracarboxylicacid-1,2,4,5-dianhydride） 1 with L-alanine 2a, L-valine 2b, L-leucine 2c, L-isoleucine 2d, L-phenyl alanine 2e and L-2-aminobutyric acid 2f in acetic acid solution.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10874009,11074011 and 91436210the International Science&Technology Cooperation Program of China under Grant No 2010DFR10900
文摘The experimental scheme of 633 nm and 1359 nm good-bad cavity dual-wavelength active optical frequency stan- dard is proposed, where He-Ne 633nm and Cs 1359nm stimulated emissions are working at good-cavity and bad-cavity regimes, respectively. The cavity length is stabilized by locking the 633nm output frequency to a super-cavity with the Pound Drever-Hall （PDH） technique. The frequency stability of 1359 nm bad-cavity stim- ulated emission output is then expected to be further improved by at least 1 order of magnitude than the 633nm PDH system due to the suppressed cavity pulling effect of active optical clock, and the quantum limited linewidth of 1359nm output is estimated to be 72.5 mHz.
基金Project(50174059)supported by the National Natural Science Foundation of ChinaProject(Y406469)supported by Natural Science Foundation of Zhejiang Province
文摘With sol-gel method,nanometer La-Ti composite oxides were prepared.By means of atomic force microscope,the surface pattern,particle size distribution and specific surface area were studied.The newly prepared nanocrystals of La-Ti composite oxides were used as the catalysts to catalyze the dehydration of external compensated lactic acid to lactide.The lactide product was measured by polarimeter and micropolariscope.The results demonstrate that the ratio between D-lactide and L-lactide will not be equal to 1-1 if nanocrystals of La-Ti composite oxides are used as the catalysts,which implies,that nanocrystals of La-Ti composite oxides may be potential catalysts with a good selectivity.
基金This project was supported by National Natural Science Foundation of China.
文摘Optically active (R)-(+)-2, 2' -bis(2 -trifluoro-4 -aminophenoxy)- 1, 1' -binaphthyl was prepared from1, 1'-bi-2-naphthol. The optically active aromatic polyimide was also successfully synthesized. This newpolymer has good solubility, thermal stability etc. Its specific rotation was found to be +174°, and itschiroptical property was also studied.
基金Project supported by the National Natural Science Foundation of China(Grant No.61078060)the Fund from the Ningbo Optoelectronic Materials and Devices Creative Team,China(Grant No.2009B21007)partially sponsored by K.C.Wong Magna Fund in Ningbo University
文摘Just like an electronic diode that allows the electrical current to flow in one direction only, a kind of chiral metamaterial structure with a similar functionality for the electromagnetic wave is proposed. The designed nanostructure that consists of twisted metallic split-ring resonators on both sides of a dielectric substrate achieves asymmetric transmission for a forward and backward propagating linearly polarized wave by numerical simulation in near-infrared band. Difference in transmission efficiency of the optimized structure between the same polarized waves incident from opposite directions can reach a maximum at the communication wavelength （1.55 μm）. Moreover, the simulation results of this structure also exhibit strong optical activity and circular dichroism.
基金We are grate ful to the National Natural Science Foundation of China for the f inancial support of this work.
文摘A new kind of hydrazone (I) diastereoisomers was prepared with enantiomeric hydazide (II) and chiral cluster (III), which was characterized by HMBC. Unfortunately, the mixture could not be separated into pure diastereoisomer. This could be a direction to separate the racemic chiral clusters.
文摘Isatoic anhydride was reacted with several L-amino acids to give the corresponding （2S）-N-（o-aminobenzoyl）-2-alkylaminoacetic acids. The latter compounds were treated with phosphoryl chloride under reflux temperature to afford the cyclized products, （3S）-3-alkyl-3,4-dihydro- 1 H- 1,4-benzodiazepin-2,5-diones. 2007 M. Bakavoli. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘The organic salts as initiators [A*B-+(-):Ph*3C+ClO4-, Ph(3)*C+SbCl6-, (-)Sp*(ClO4-)-Cl-+ and (-)(Sp)(2)*(+3)(ClO4-)(3)] and catalysts [A(+)B*(-):(+)CSA*, A*B-+*(-):Ph(3)*C+(+)CSA*(-) and (-)Sp*(+)(+)CSA*] are prepared and characterized by specific rotation. The asymmetrically stereoselective induction of the initiators and catalysts in thc polymerization of N-vinylcarbazole is in an order of A*B-+*(-) > A(+)B*(-) > A*B-+(-). The specific rotations of obtained poly(N-vinylcarbazole) (PVCZ) generally are in accordance with mentioned order.
