污泥预处理方法包括机械法、化学法和生物法,选择上述方法中具有代表性的超声波20 k Hz、p H 10和厌氧70℃分别预处理污泥,从有机物释放情况和经济性评价不同预处理方法.结果表明,污泥经过预处理后,液相中有机物释放量均增多,但经过p H...污泥预处理方法包括机械法、化学法和生物法,选择上述方法中具有代表性的超声波20 k Hz、p H 10和厌氧70℃分别预处理污泥,从有机物释放情况和经济性评价不同预处理方法.结果表明,污泥经过预处理后,液相中有机物释放量均增多,但经过p H 10和厌氧70℃预处理后能释放更多的有机物,反应结束时其总溶解性蛋白质和多糖由预处理前的418.9mg·L^-1(以COD计,下同)分别增加到7 516.0 mg·L^-1和7 892.5 mg·L^-1,DNA浓度由预处理前的18.1 mg·L^-1依次增加到1 343.3 mg·L^-1和1 766.1 mg·L^-1;通过流式细胞术鉴定细胞形态得出预处理结束时污泥细胞死亡率从高到低为61.6%(p H10)、59.9%(厌氧70℃)和34.5%(超声波20 k Hz),相比预处理前分别提高45.6%、43.9%和18.5%;预处理结束时污泥有机物去除率依次为19.1%(p H 10)、13.8%(厌氧70℃)和7.6%(超声波20 k Hz);单位体积污泥经p H 10预处理比超声-20kHz和厌氧70℃分别多节约28.5%和124.1%.基于本研究中污泥有机物释放量和经济性,污泥预处理方法宜选择化学法(p H 10).展开更多
A compact linearly polarized, low-noise, narrow-linewidth, single-frequency fiber laser at 1950nm is demonstrated. This compact fiber laser is based on a 21-mm-long homemade Tm3＋-doped germanate glass fiber. Over 100...A compact linearly polarized, low-noise, narrow-linewidth, single-frequency fiber laser at 1950nm is demonstrated. This compact fiber laser is based on a 21-mm-long homemade Tm3＋-doped germanate glass fiber. Over 100-mW stable continuous-wave single transverse and longitudinal mode lasing at 195Ohm are achieved. The measured relative intensity noise is less than -135dB/Hz at frequencies over 5 MHz. The signal-to-noise ratio of the laser is larger than 72dB, and the laser linewidth is less than 6kHz, while the obtained linear polarization extinction ratio is higher than 22 dB.展开更多
A method to identify complex Young＇s modulus of viscoelastic materials using forced longitudinal vibration of slender rods is proposed. The method differs from the beam one. Experimental tests were carried out at roo...A method to identify complex Young＇s modulus of viscoelastic materials using forced longitudinal vibration of slender rods is proposed. The method differs from the beam one. Experimental tests were carried out at room temperature with different lengths in 108 mm, 100 mm, 90 ram, 83.5 mm, 80 ram, 74.5 mm, 70 mm for the polycarbonate bars, and the curves of ratios A2/A1 between two ends of a viscoelastic bar versus frequencies are obtained, furthermore, the corresponding 3 dB bandwidth and the storage and loss modulus can be calculated. Sufficient number of obtained complex Young＇s modulus at different frequency allows us to calculate other ones using the least square method. If the step of the tested frequency is 5 Hz, the maximum error of results can be less than 6%. By comparison with the measurement methods which the previous literature mentioned, this new method simplifies the calculation, and the physical meaning appears apparently and clearly.展开更多
A Q-switched distributed Bragg reflector fiber laser using a graphene passive saturable absorber is proposed in a cavity consisting of a fiber Bragg grating and Faraday rotator mirror as end mirrors, together with a h...A Q-switched distributed Bragg reflector fiber laser using a graphene passive saturable absorber is proposed in a cavity consisting of a fiber Bragg grating and Faraday rotator mirror as end mirrors, together with a highly doped erbium-doped fiber as a gain source. The laser has a Q-switched threshold of about 28 mW and a tunable repetition rate of 10.4-18.0 kHz with varying pump power. The shortest pulse width obtained from the system is 3.7 its, with a maximum pulse energy and peak power of 22.2 nJ and 3.4 mW, respectively.展开更多
A pulsed laser system is realized with graphene employed as a Q-switch.The graphene is exfoliated from its solution using an optical deposition and the optical tweezer effect.A fiber ferrule that already has the graph...A pulsed laser system is realized with graphene employed as a Q-switch.The graphene is exfoliated from its solution using an optical deposition and the optical tweezer effect.A fiber ferrule that already has the graphene deposited on it is inserted into an erbium-ytterbium laser（EYL）system with linear cavity configuration.We successfully demonstrate a pulsed EYL with a pulse duration of approximately 5.9μs and a repetition rate of 20.0 kHz.展开更多
Effective multiple optoelectronic feedback circuits for simultaneously suppressing low-frequency and relaxation oscillation intensity noise in a single-frequency phosphate fiber laser are demonstrated. The forward tra...Effective multiple optoelectronic feedback circuits for simultaneously suppressing low-frequency and relaxation oscillation intensity noise in a single-frequency phosphate fiber laser are demonstrated. The forward transfer function, which relates the laser output intensity to the pump modulations, is measured and analyzed. A custom two-path feedback system operating at different frequency bands is designed to adjust the pump current directly. The relative intensity noise is decreased by 20dB from 0.2 to 5kHz and over lOdB from 5 to lOkHz. The relaxation oscillation peak is suppressed by 22dB. In addition, a long term （24h） laser instability of less than 0.05% is achieved.展开更多
We report a hybrid femtosecond laser system based on a femtosecond Yb-doped fiber laser and a Yb-doped potassium gadolinium tungstate(Yb:KGW) regenerative amplifier. To match the central wavelength of the seed source,...We report a hybrid femtosecond laser system based on a femtosecond Yb-doped fiber laser and a Yb-doped potassium gadolinium tungstate(Yb:KGW) regenerative amplifier. To match the central wavelength of the seed source, a Yb:KGW crystal is used in the regenerative amplifier for N_p polarization. We study and optimize the dynamics of nonlinear amplification to alleviate the gain narrowing effect. With optimization, the system can output 270 fs pulses with 21 μJ pulse energy at a 60 kHz repetition rate.展开更多
In the present study we evaluated the effects of chronic exposure to sounds at 22 kHz during pregnancy on the central serotonergic and behavioral parameters in Wistar rat dams after the suckling period and on their ma...In the present study we evaluated the effects of chronic exposure to sounds at 22 kHz during pregnancy on the central serotonergic and behavioral parameters in Wistar rat dams after the suckling period and on their male rat offspring. In addition, we also assessed the effects of an acute 22 kHz sound, associated with the chronic intrauterine exposure, on the emotional responses of adult offspring. The primary hypothesis was that experiencing 22 kHz stimuli during an early stage of development would interfere with brain serotonergic parameters and, later, with the adult rat’s defensive responses. The corollary question was whether a 22 kHz sound exposure would differentially affect inhibitory avoidance and escape responses and central serotonergic parameters. Female rats were divided into four groups: non-pregnant control;non-pregnant chronic exposure;pregnant control;and pregnant chronic exposure. Male offspring were divided into four groups: chronic intrauterine sound exposure;acute sound exposure in adulthood;chronic intrauterine exposure with acute exposure in adulthood;and no exposure. Chronic sound exposure affected inhibitory avoidance and serotonergic parameters in female rats. For offspring, there was an interaction between chronic and acute sound exposure effects on inhibitory avoidance response but not on escape response. There were significant effects of chronic intrauterine exposure on serotonin turnover in the hippocampus and PFC of females. For offspring, the turnover was increased by chronic exposure only in PFC, and in amygdala it was increased by acute exposure. These results illuminate the potential of an early acoustic sound exposure for causing central serotonergic and emotional behavioral changes that can persist into later periods of life.展开更多
We briefly review the proposed relations between the frequencies of twin kilohertz quasi-periodic oscillations(kHz QPOs) and the spin frequencies in neutron star low-mass X-ray binaries(NSLMXBs).To test the validity o...We briefly review the proposed relations between the frequencies of twin kilohertz quasi-periodic oscillations(kHz QPOs) and the spin frequencies in neutron star low-mass X-ray binaries(NSLMXBs).To test the validity of the proposed models,we estimate the spin frequencies under these theoretical relations and compare them with the measured ones.It seems that magnetohydrodynamic(MHD) oscillations are more promising to account for the kHz QPOs.展开更多
Based the Alfven wave oscillation model(AWOM) and relativistic precession model(RPM) for twin kHz QPOs,we estimate the emission positions of most detected kHz QPOs to be at r=18+/-3 km(R/15 km),except Cir X-1 at r-30+...Based the Alfven wave oscillation model(AWOM) and relativistic precession model(RPM) for twin kHz QPOs,we estimate the emission positions of most detected kHz QPOs to be at r=18+/-3 km(R/15 km),except Cir X-1 at r-30+/-5 km(R/15 km).For the proposed Keplerian frequency as an upper limit to kHz QPO,the spin effects in Kerr Spacetime are discussed,which have about a 5%(2%) modification for that of the Schwarzchild case for the spin frequency of 1000(400) Hz.The application to the four typical QPO sources,Cir X-1,Sco X-1,SAX J1808.4-3658 and XTE 1807-294,is mentioned.展开更多
文摘污泥预处理方法包括机械法、化学法和生物法,选择上述方法中具有代表性的超声波20 k Hz、p H 10和厌氧70℃分别预处理污泥,从有机物释放情况和经济性评价不同预处理方法.结果表明,污泥经过预处理后,液相中有机物释放量均增多,但经过p H 10和厌氧70℃预处理后能释放更多的有机物,反应结束时其总溶解性蛋白质和多糖由预处理前的418.9mg·L^-1(以COD计,下同)分别增加到7 516.0 mg·L^-1和7 892.5 mg·L^-1,DNA浓度由预处理前的18.1 mg·L^-1依次增加到1 343.3 mg·L^-1和1 766.1 mg·L^-1;通过流式细胞术鉴定细胞形态得出预处理结束时污泥细胞死亡率从高到低为61.6%(p H10)、59.9%(厌氧70℃)和34.5%(超声波20 k Hz),相比预处理前分别提高45.6%、43.9%和18.5%;预处理结束时污泥有机物去除率依次为19.1%(p H 10)、13.8%(厌氧70℃)和7.6%(超声波20 k Hz);单位体积污泥经p H 10预处理比超声-20kHz和厌氧70℃分别多节约28.5%和124.1%.基于本研究中污泥有机物释放量和经济性,污泥预处理方法宜选择化学法(p H 10).
基金Supported by the National High-Technology Research and Development Program of China under Grant Nos 2013AA031502 and 2014AA041902the National Natural Science Foundation of China under Grant Nos 11174085,51132004,and 51302086+3 种基金the Natural Science Foundation of Guangdong Province under Grant Nos S2011030001349 and S20120011380the China National Funds for Distinguished Young Scientists under Grant No 61325024the Science and Technology Project of Guangdong Province under Grant No 2013B090500028the ’Cross and Cooperative’ Science and Technology Innovation Team Project of Chinese Academy of Sciences under Grant No 2012-119
文摘A compact linearly polarized, low-noise, narrow-linewidth, single-frequency fiber laser at 1950nm is demonstrated. This compact fiber laser is based on a 21-mm-long homemade Tm3＋-doped germanate glass fiber. Over 100-mW stable continuous-wave single transverse and longitudinal mode lasing at 195Ohm are achieved. The measured relative intensity noise is less than -135dB/Hz at frequencies over 5 MHz. The signal-to-noise ratio of the laser is larger than 72dB, and the laser linewidth is less than 6kHz, while the obtained linear polarization extinction ratio is higher than 22 dB.
基金supported by the Fundamental Research Funds of China for the Central Universities(GK201001008)
文摘A method to identify complex Young＇s modulus of viscoelastic materials using forced longitudinal vibration of slender rods is proposed. The method differs from the beam one. Experimental tests were carried out at room temperature with different lengths in 108 mm, 100 mm, 90 ram, 83.5 mm, 80 ram, 74.5 mm, 70 mm for the polycarbonate bars, and the curves of ratios A2/A1 between two ends of a viscoelastic bar versus frequencies are obtained, furthermore, the corresponding 3 dB bandwidth and the storage and loss modulus can be calculated. Sufficient number of obtained complex Young＇s modulus at different frequency allows us to calculate other ones using the least square method. If the step of the tested frequency is 5 Hz, the maximum error of results can be less than 6%. By comparison with the measurement methods which the previous literature mentioned, this new method simplifies the calculation, and the physical meaning appears apparently and clearly.
基金supported by the Ministry of Higher Education/University of Malaya(Nos.UM.C/HIR/MOHE/SC/01 and UPGP2012)
文摘A Q-switched distributed Bragg reflector fiber laser using a graphene passive saturable absorber is proposed in a cavity consisting of a fiber Bragg grating and Faraday rotator mirror as end mirrors, together with a highly doped erbium-doped fiber as a gain source. The laser has a Q-switched threshold of about 28 mW and a tunable repetition rate of 10.4-18.0 kHz with varying pump power. The shortest pulse width obtained from the system is 3.7 its, with a maximum pulse energy and peak power of 22.2 nJ and 3.4 mW, respectively.
文摘A pulsed laser system is realized with graphene employed as a Q-switch.The graphene is exfoliated from its solution using an optical deposition and the optical tweezer effect.A fiber ferrule that already has the graphene deposited on it is inserted into an erbium-ytterbium laser（EYL）system with linear cavity configuration.We successfully demonstrate a pulsed EYL with a pulse duration of approximately 5.9μs and a repetition rate of 20.0 kHz.
基金Supported by the National High-Technology Research and Development Program of China under Grant Nos 2013AA031502 and 2014AA041902the National Natural Science Foundation of China under Grant Nos 11174085,51132004,and 51302086+3 种基金the Guangdong Natural Science Foundation under Grant Nos S2011030001349 and S20120011380the China National Funds for Distinguished Young Scientists under Grant No 61325024the Science and Technology Project of Guangdong Province under Grant No 2013B090500028the’Cross and Cooperative’Science and Technology Innovation Team Project of Chinese Academy of Sciences under Grant No 2012-119
文摘Effective multiple optoelectronic feedback circuits for simultaneously suppressing low-frequency and relaxation oscillation intensity noise in a single-frequency phosphate fiber laser are demonstrated. The forward transfer function, which relates the laser output intensity to the pump modulations, is measured and analyzed. A custom two-path feedback system operating at different frequency bands is designed to adjust the pump current directly. The relative intensity noise is decreased by 20dB from 0.2 to 5kHz and over lOdB from 5 to lOkHz. The relaxation oscillation peak is suppressed by 22dB. In addition, a long term （24h） laser instability of less than 0.05% is achieved.
基金supported by the National Natural Science Foundation of China(Nos.61805174,U1730115,61535009,and 11527808)the Open Fund of the State Key Laboratory of High Field Laser Physics(Shanghai Institute of Optics and Fine Mechanics)
文摘We report a hybrid femtosecond laser system based on a femtosecond Yb-doped fiber laser and a Yb-doped potassium gadolinium tungstate(Yb:KGW) regenerative amplifier. To match the central wavelength of the seed source, a Yb:KGW crystal is used in the regenerative amplifier for N_p polarization. We study and optimize the dynamics of nonlinear amplification to alleviate the gain narrowing effect. With optimization, the system can output 270 fs pulses with 21 μJ pulse energy at a 60 kHz repetition rate.
文摘In the present study we evaluated the effects of chronic exposure to sounds at 22 kHz during pregnancy on the central serotonergic and behavioral parameters in Wistar rat dams after the suckling period and on their male rat offspring. In addition, we also assessed the effects of an acute 22 kHz sound, associated with the chronic intrauterine exposure, on the emotional responses of adult offspring. The primary hypothesis was that experiencing 22 kHz stimuli during an early stage of development would interfere with brain serotonergic parameters and, later, with the adult rat’s defensive responses. The corollary question was whether a 22 kHz sound exposure would differentially affect inhibitory avoidance and escape responses and central serotonergic parameters. Female rats were divided into four groups: non-pregnant control;non-pregnant chronic exposure;pregnant control;and pregnant chronic exposure. Male offspring were divided into four groups: chronic intrauterine sound exposure;acute sound exposure in adulthood;chronic intrauterine exposure with acute exposure in adulthood;and no exposure. Chronic sound exposure affected inhibitory avoidance and serotonergic parameters in female rats. For offspring, there was an interaction between chronic and acute sound exposure effects on inhibitory avoidance response but not on escape response. There were significant effects of chronic intrauterine exposure on serotonin turnover in the hippocampus and PFC of females. For offspring, the turnover was increased by chronic exposure only in PFC, and in amygdala it was increased by acute exposure. These results illuminate the potential of an early acoustic sound exposure for causing central serotonergic and emotional behavioral changes that can persist into later periods of life.
基金supported by the National Natural Science Foundation of China (Grant No. 10873008)the National Basic Research Program of China (Grant No. 2009CB824800)
文摘We briefly review the proposed relations between the frequencies of twin kilohertz quasi-periodic oscillations(kHz QPOs) and the spin frequencies in neutron star low-mass X-ray binaries(NSLMXBs).To test the validity of the proposed models,we estimate the spin frequencies under these theoretical relations and compare them with the measured ones.It seems that magnetohydrodynamic(MHD) oscillations are more promising to account for the kHz QPOs.
基金supported by the National Basic Research Program of China (Grant No. 2009CB824800)the National Natural Science Foundation of China (Grant No. 10773017)
文摘Based the Alfven wave oscillation model(AWOM) and relativistic precession model(RPM) for twin kHz QPOs,we estimate the emission positions of most detected kHz QPOs to be at r=18+/-3 km(R/15 km),except Cir X-1 at r-30+/-5 km(R/15 km).For the proposed Keplerian frequency as an upper limit to kHz QPO,the spin effects in Kerr Spacetime are discussed,which have about a 5%(2%) modification for that of the Schwarzchild case for the spin frequency of 1000(400) Hz.The application to the four typical QPO sources,Cir X-1,Sco X-1,SAX J1808.4-3658 and XTE 1807-294,is mentioned.
