We demonstrate a Fe:ZnSe laser gain-switched by a 2.9 m ZnGeP2 optical parametric oscillator under pulse repetition frequency of 1 kHz at liquid nitrogen temperature of 77 K. The maximum output power is 63 m W with pu...We demonstrate a Fe:ZnSe laser gain-switched by a 2.9 m ZnGeP2 optical parametric oscillator under pulse repetition frequency of 1 kHz at liquid nitrogen temperature of 77 K. The maximum output power is 63 m W with pulse duration of 34.4 ns. The wavelength covers 3686.6–4088.6 nm and centers at 3897.7 nm. The output power decreases with increasing the temperature of the crystal in 77–222 K.展开更多
We demonstrated an Fe:ZnSe laser pumped by a 2.93-μm Cr, Er:YAG laser at liquid nitrogen and room temperature in single-shot free-running operation for the first time. The xenon flash lamp pumped Cr, Er:YAG laser had...We demonstrated an Fe:ZnSe laser pumped by a 2.93-μm Cr, Er:YAG laser at liquid nitrogen and room temperature in single-shot free-running operation for the first time. The xenon flash lamp pumped Cr, Er:YAG laser had a maximum single pulse energy of 1.414 J, and the threshold and slope efficiency were 141.70 J and 0.70% which were respectively reduced by 29.3% and increased by 52.2% compared with the Er:YAG laser. At liquid nitrogen temperature of 77 K, the maximum single pulse energy of the Fe:ZnSe laser was 197.6 m J, corresponding to a slope efficiency of 13.4%. The central wavelength and full width at half maximum(FWHM) linewidth were 4037.4 nm and 122.0 nm, respectively. At room temperature, the laser generated a maximum single pulse energy of 3.5 mJ at the central wavelength of 4509.6 nm with an FWHM linewidth of 171.5 nm.展开更多
We demonstrate a gain-switched Fe:ZnSe laser pumped by a 2958 nm pulsed Ho,Pr:LLF laser. The maximum single pulse energy is 16.4uJ with a minimum pulse duration of 13.9 ns at the pulse repetition frequency of1 Hz when...We demonstrate a gain-switched Fe:ZnSe laser pumped by a 2958 nm pulsed Ho,Pr:LLF laser. The maximum single pulse energy is 16.4uJ with a minimum pulse duration of 13.9 ns at the pulse repetition frequency of1 Hz when the Fe:ZnSe crystal is cooled to 77 K by liquid nitrogen, corresponding to a slope efficiency of 22.9%.The central wavelength and FWHM linewidth are 3957.4 nm and 23.2 nm, respectively. The output energy monotonically decreases as the crystal temperature increases in the range 77–293 K.展开更多
High-nitrogen (N) austenitic stainless steel (Cr-Mn-N series) is commonly used for non-magnetic drill collars, which exhibits excellent mechanical properties and corrosion resistance. The effects of N content (0.63 to...High-nitrogen (N) austenitic stainless steel (Cr-Mn-N series) is commonly used for non-magnetic drill collars, which exhibits excellent mechanical properties and corrosion resistance. The effects of N content (0.63 to 0.86 wt.%) on the pitting corrosion behavior of the experimental non-magnetic drill collar steel were investigated using the electrochemical tests and immersion tests. Besides, X-ray photoelectron spectroscopy was used to analyze the constitution of the passive film. The results show that with the enhancement of N content from 0.63 to 0.86 wt.%, the metastable pitting corrosion sensitivity of the tested materials in 3.5 wt.% NaCl solution decreased and the pitting corrosion resistance increased. Meanwhile, the corrosion rate in 6 wt.% FeCl3 solution at 30 ℃ decreased from 10.40 to 4.93 mm/a. On the other hand, nitrogen was concentrated in the form of ammonia (NH4+ and NH3)on the outermost surface of the passive films. The contents of Cr2O3 and Fe2O3 raised in the passive films, together with the content of CrN, at metal/film interface increased as N content increased from 0.63 to 0.86 wt.%, which facilitated protective ability of the passive films, thus contributing to higher pitting corrosion resistance.展开更多
Tagetes L.,the genus in the family Asteraceae,consists of about 30 species spread in South and Middle America as well as Mexico.More than one hundred secondary metabolites have been obtained in phytochemical investiga...Tagetes L.,the genus in the family Asteraceae,consists of about 30 species spread in South and Middle America as well as Mexico.More than one hundred secondary metabolites have been obtained in phytochemical investigation on the species,some of which have potent biological activities.The advances in phytochemical studies and biological activities of the plants in Tagetes L.from 1925 to 2011 are summarized in this paper.展开更多
Precipitation behavior of P550 steel for non-magnetic drill collars was investigated by microstructure characterization as well as thermodynamic calculation.The results demonstrate that the main precipitate formed at ...Precipitation behavior of P550 steel for non-magnetic drill collars was investigated by microstructure characterization as well as thermodynamic calculation.The results demonstrate that the main precipitate formed at 650–900℃was cellular Cr_(2)N,and its precipitation depended heavily on the aging temperature.The most sensitive precipitation temperature of cellular Cr_(2)N was 750℃.At 750℃,the cellular Cr_(2)N exhibited fast-slow precipitation kinetics with the aging time prolonging.The initial precipitation of cellular Cr_(2)N was governed by the short-range intergranular diffusion of Cr.During long-term aging,its growth was controlled by the long-range bulk diffusion of Cr.In addition,cellular Cr_(2)N induced the precipitation of r phase ahead of the cell after long period of aging.Increasing the nitrogen content resulted in the increment of both the nucleation site and the driving force for the cellular Cr_(2)N,which jointly promoted its precipitation.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 51572053the Science Fund for Outstanding Youths of Heilongjiang Province under Grant No JQ201310
文摘We demonstrate a Fe:ZnSe laser gain-switched by a 2.9 m ZnGeP2 optical parametric oscillator under pulse repetition frequency of 1 kHz at liquid nitrogen temperature of 77 K. The maximum output power is 63 m W with pulse duration of 34.4 ns. The wavelength covers 3686.6–4088.6 nm and centers at 3897.7 nm. The output power decreases with increasing the temperature of the crystal in 77–222 K.
基金Project supported by the National Natural Science Foundation of China(Grant No.61405047)
文摘We demonstrated an Fe:ZnSe laser pumped by a 2.93-μm Cr, Er:YAG laser at liquid nitrogen and room temperature in single-shot free-running operation for the first time. The xenon flash lamp pumped Cr, Er:YAG laser had a maximum single pulse energy of 1.414 J, and the threshold and slope efficiency were 141.70 J and 0.70% which were respectively reduced by 29.3% and increased by 52.2% compared with the Er:YAG laser. At liquid nitrogen temperature of 77 K, the maximum single pulse energy of the Fe:ZnSe laser was 197.6 m J, corresponding to a slope efficiency of 13.4%. The central wavelength and full width at half maximum(FWHM) linewidth were 4037.4 nm and 122.0 nm, respectively. At room temperature, the laser generated a maximum single pulse energy of 3.5 mJ at the central wavelength of 4509.6 nm with an FWHM linewidth of 171.5 nm.
基金the National Natural Science Foundation of China under Grant No 61405047
文摘We demonstrate a gain-switched Fe:ZnSe laser pumped by a 2958 nm pulsed Ho,Pr:LLF laser. The maximum single pulse energy is 16.4uJ with a minimum pulse duration of 13.9 ns at the pulse repetition frequency of1 Hz when the Fe:ZnSe crystal is cooled to 77 K by liquid nitrogen, corresponding to a slope efficiency of 22.9%.The central wavelength and FWHM linewidth are 3957.4 nm and 23.2 nm, respectively. The output energy monotonically decreases as the crystal temperature increases in the range 77–293 K.
基金the National Nat-ural Science Foundation of China(Grant Nos.U1960203,51774074 and 51434004)Shanxi Municipal Major Science and Technology Project(Grant No.20181101014)+2 种基金Fundamental Research Funds for the Central Universities(Grant Nos.N172512033 and N2024005-4)Talent Project of Revitalizing Liaoning(XLYC1902046)State Key Laboratory of Metal Material for Marine Equipment and Application(Grant No.HG-SKL(2019)13).
文摘High-nitrogen (N) austenitic stainless steel (Cr-Mn-N series) is commonly used for non-magnetic drill collars, which exhibits excellent mechanical properties and corrosion resistance. The effects of N content (0.63 to 0.86 wt.%) on the pitting corrosion behavior of the experimental non-magnetic drill collar steel were investigated using the electrochemical tests and immersion tests. Besides, X-ray photoelectron spectroscopy was used to analyze the constitution of the passive film. The results show that with the enhancement of N content from 0.63 to 0.86 wt.%, the metastable pitting corrosion sensitivity of the tested materials in 3.5 wt.% NaCl solution decreased and the pitting corrosion resistance increased. Meanwhile, the corrosion rate in 6 wt.% FeCl3 solution at 30 ℃ decreased from 10.40 to 4.93 mm/a. On the other hand, nitrogen was concentrated in the form of ammonia (NH4+ and NH3)on the outermost surface of the passive films. The contents of Cr2O3 and Fe2O3 raised in the passive films, together with the content of CrN, at metal/film interface increased as N content increased from 0.63 to 0.86 wt.%, which facilitated protective ability of the passive films, thus contributing to higher pitting corrosion resistance.
基金Project supported by the Medical Health Program of Zhejiang Province(No.2014ZDA011)the Zhejiang Provincial Natural Science Foundation of China(No.2015KYB222)
基金The Western High-tech Project Action Plan (KG-CX2-YW-510)Important Directional Project, Chinese Academy of Sciences (KSCX2-EW-R-15)
文摘Tagetes L.,the genus in the family Asteraceae,consists of about 30 species spread in South and Middle America as well as Mexico.More than one hundred secondary metabolites have been obtained in phytochemical investigation on the species,some of which have potent biological activities.The advances in phytochemical studies and biological activities of the plants in Tagetes L.from 1925 to 2011 are summarized in this paper.
基金the National Natural Science Foundation of China(Grant Nos.U1960203 and 51774074)Shanxi Municipal Major Science&Technology Project(Grant No.20181101014)+2 种基金Fundamental Research Funds for the Central Universities(Grant Nos.N172512033 and N2024005-4)Talent Project of Revitalizing Liaoning(XLYC1902046)State Key Laboratory of Metal Material for Marine Equipment and Application(Grant No.HG-SKL(2019)13).
文摘Precipitation behavior of P550 steel for non-magnetic drill collars was investigated by microstructure characterization as well as thermodynamic calculation.The results demonstrate that the main precipitate formed at 650–900℃was cellular Cr_(2)N,and its precipitation depended heavily on the aging temperature.The most sensitive precipitation temperature of cellular Cr_(2)N was 750℃.At 750℃,the cellular Cr_(2)N exhibited fast-slow precipitation kinetics with the aging time prolonging.The initial precipitation of cellular Cr_(2)N was governed by the short-range intergranular diffusion of Cr.During long-term aging,its growth was controlled by the long-range bulk diffusion of Cr.In addition,cellular Cr_(2)N induced the precipitation of r phase ahead of the cell after long period of aging.Increasing the nitrogen content resulted in the increment of both the nucleation site and the driving force for the cellular Cr_(2)N,which jointly promoted its precipitation.
