We report on using synthetic silicon for a high-precision X-ray polarimeter comprising a polarizer and an analyzer,each based on a monolithic channel-cut crystal used at multiple Brewster reflections with a Bragg angl...We report on using synthetic silicon for a high-precision X-ray polarimeter comprising a polarizer and an analyzer,each based on a monolithic channel-cut crystal used at multiple Brewster reflections with a Bragg angle very close to 45°.Experiments were performed at the BL09B bending magnet beamline of the Shanghai Synchrotron Radiation Facility using a Si(800)crystal at an X-ray energy of 12.914 keV.A polarization purity of 8.4×10^(-9)was measured.This result is encouraging,as the measured polarization purity is the best-reported value for the bending magnet source.Notably,this is the firstly systematic study on the hard X-ray polarimeter in China,which is crucial for exploring new physics,such as verifying vacuum birefringence.展开更多
AIM: To investigate the efficacy and safety of ulinastatin for patients with acute lung injury(ALI) and those with acute respiratory distress syndrome(ARDS).METHODS: A systematic review of randomized controlled trials...AIM: To investigate the efficacy and safety of ulinastatin for patients with acute lung injury(ALI) and those with acute respiratory distress syndrome(ARDS).METHODS: A systematic review of randomized controlled trials(RCTs) of ulinastatin for ALI/ARDS was conducted. Oxygenation index, mortality rate [intensive care unit(ICU) mortality rate, 28-d mortality rate] and length of ICU stay were compared between ulinastatin group and conventional therapy group. Meta-analysis was performed by using Rev Man 5.1.RESULTS: Twenty-nine RCTs with 1726 participants were totally included, the basic conditions of which were similar. No studies discussed adverse effect. Oxygenation index was reported in twenty-six studies(1552 patients). Ulinastatin had a significant effect in improving oxygenation [standard mean difference(SMD) = 1.85, 95%CI: 1.42-2.29, P < 0.00001, I2 = 92%]. ICUmortality and 28-d mortality were respectively reported in eighteen studies(987 patients) and three studies(196 patients). We found that ulinastatin significantly decreased the ICU mortality [I2 = 0%, RR = 0.48, 95%CI: 0.38-0.59, number needed to treat(NNT) = 5.06, P < 0.00001], while the 28-d mortality was not significantly affected(I2 = 0%, RR = 0.78, 95%CI: 0.51-1.19, NNT = 12.66, P = 0.24). The length of ICU stay(six studies, 364 patients) in the ulinastatin group was significantly lower than that in the control group(SMD =-0.97, 95%CI:-1.20--0.75, P < 0.00001, I2 = 86%). CONCLUSION: Ulinastatin seems to be effective for ALI and ARDS though most trials included were of poor quality and no information on safety was provided.展开更多
The compression of high-energy, linearly polarized pulses in a gas-filled hollow core fiber(HCF) by using a concentric phase mask is studied theoretically. Simulation results indicate that using a properly designed co...The compression of high-energy, linearly polarized pulses in a gas-filled hollow core fiber(HCF) by using a concentric phase mask is studied theoretically. Simulation results indicate that using a properly designed concentric phase mask, a40-fs input pulse centered at 800 nm with energy up to 10.0 mJ can be compressed to a full width at half maximum(FWHM) of less than 5 fs after propagating through a neon-filled HCF with a length of 1 m and diameter of 500 μm with a transmission efficiency of 67%, which is significantly higher than that without a concentric phase mask. Pulses with energy up to 20.0 mJ can also be efficiently compressed to less than 10 fs with the concentric phase mask. The higher efficiency due to the concentric phase mask can be attributed to the redistribution of the transverse intensity profile, which reduces the effect of ionization. The proposed method exhibits great potential for generating few-cycle laser pulse sources with high energy by the HCF compressor.展开更多
We perform a numerical study for temporally compressing radially-polarized（RP） infrared pulses in a gas-filled hollow-core fiber（HCF）. The dynamic transmission and nonlinear compression of RP pulses centered at wa...We perform a numerical study for temporally compressing radially-polarized（RP） infrared pulses in a gas-filled hollow-core fiber（HCF）. The dynamic transmission and nonlinear compression of RP pulses centered at wavelengths of0.8 m, 1.8 m, 3.1 m, and 5.0 m in HCFs are simulated. By comparing the propagation of pulses with the same optical cycles and intensity, we find that under proper conditions these pulses can be compressed down to 2–3 cycles. In the transverse direction, the spatiotemporal beam profile ameliorates from 0.8-m to 1.8-m and 3.1-m pulses before the appearance of high-order dispersion. These results show an alternative method of scaling generation for delivering RP infrared pulses in gas-filled HCFs, which can obtain energetic few-cycle pulses, and will be beneficial for relevant researches in the infrared scope.展开更多
We numerically study the propagation dynamics of intense optical pulses in gas-filled hollow-core fibers（HCFs）. The spatiotemporal dynamics of the pulses show a transition from tightly confined to loosely confined c...We numerically study the propagation dynamics of intense optical pulses in gas-filled hollow-core fibers（HCFs）. The spatiotemporal dynamics of the pulses show a transition from tightly confined to loosely confined characteristics as the fiber core is increased, which manifests as a deterioration in the spatiotemporal uniformity of the beam. It is found that using the gas pressure gradient does not enhance the beam quality in large-core HCFs, while inducing a positive chirp in the pulse to lower the peak power can improve the beam quality. This indicates that the self-focusing effect in the HCFs is the main driving force for the propagation dynamics. It also suggests that pulses at longer wavelengths are more suitable for HCFs with large cores because of the lower critical power of self-focusing, which is justified by the numerical simulations. These results will benefit the generation of energetic few-cycle pulses in large-core HCFs.展开更多
We present a cascaded nonlinear spectral broadening scheme for Nd-doped lasers,featuring with long pulse duration and high average power.This scheme is based on two multi-pass cells(MPCs)and one multiple-plate superco...We present a cascaded nonlinear spectral broadening scheme for Nd-doped lasers,featuring with long pulse duration and high average power.This scheme is based on two multi-pass cells(MPCs)and one multiple-plate supercontinuum generation(MPSG),and the numerical investigation is driven by a home-made Nd-doped fiber laser with 12 ps pulse duration,50 kHz repetition rate and 100 W average power.The MPC-based first two stages allow us to broaden the pulse spectrum to 4 nm and 43 nm respectively,and subsequently,the MPSG-based third stage allows us to reach 235 nm spectral bandwidth.This broadened spectrum can support a Fourier-transfer-limited pulse duration of 9.8 fs,which is shorter than three optical cycles.To the best of our knowledge,it is the first time to demonstrate the possibility of few-cycle pulses generation based on the 10 ps level Nd-doped lasers.Such few-cycle and high average power laser sources should be attractive and prospective,benefiting from the characteristics of structure compact,low-cost and flexibility.展开更多
基金supported by the Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX02)the National Natural Science Foundation of China(No.12205360)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2018297)。
文摘We report on using synthetic silicon for a high-precision X-ray polarimeter comprising a polarizer and an analyzer,each based on a monolithic channel-cut crystal used at multiple Brewster reflections with a Bragg angle very close to 45°.Experiments were performed at the BL09B bending magnet beamline of the Shanghai Synchrotron Radiation Facility using a Si(800)crystal at an X-ray energy of 12.914 keV.A polarization purity of 8.4×10^(-9)was measured.This result is encouraging,as the measured polarization purity is the best-reported value for the bending magnet source.Notably,this is the firstly systematic study on the hard X-ray polarimeter in China,which is crucial for exploring new physics,such as verifying vacuum birefringence.
文摘AIM: To investigate the efficacy and safety of ulinastatin for patients with acute lung injury(ALI) and those with acute respiratory distress syndrome(ARDS).METHODS: A systematic review of randomized controlled trials(RCTs) of ulinastatin for ALI/ARDS was conducted. Oxygenation index, mortality rate [intensive care unit(ICU) mortality rate, 28-d mortality rate] and length of ICU stay were compared between ulinastatin group and conventional therapy group. Meta-analysis was performed by using Rev Man 5.1.RESULTS: Twenty-nine RCTs with 1726 participants were totally included, the basic conditions of which were similar. No studies discussed adverse effect. Oxygenation index was reported in twenty-six studies(1552 patients). Ulinastatin had a significant effect in improving oxygenation [standard mean difference(SMD) = 1.85, 95%CI: 1.42-2.29, P < 0.00001, I2 = 92%]. ICUmortality and 28-d mortality were respectively reported in eighteen studies(987 patients) and three studies(196 patients). We found that ulinastatin significantly decreased the ICU mortality [I2 = 0%, RR = 0.48, 95%CI: 0.38-0.59, number needed to treat(NNT) = 5.06, P < 0.00001], while the 28-d mortality was not significantly affected(I2 = 0%, RR = 0.78, 95%CI: 0.51-1.19, NNT = 12.66, P = 0.24). The length of ICU stay(six studies, 364 patients) in the ulinastatin group was significantly lower than that in the control group(SMD =-0.97, 95%CI:-1.20--0.75, P < 0.00001, I2 = 86%). CONCLUSION: Ulinastatin seems to be effective for ALI and ARDS though most trials included were of poor quality and no information on safety was provided.
基金Project supported by the National Natural Science Foundation of China(Grant No.61521093)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB1603)+1 种基金the International Science and Technology Cooperation Program of China(Grant No.2016YFE0119300)the Program of Shanghai Academic/Technology Research Leader,China(Grant No.18XD1404200)
文摘The compression of high-energy, linearly polarized pulses in a gas-filled hollow core fiber(HCF) by using a concentric phase mask is studied theoretically. Simulation results indicate that using a properly designed concentric phase mask, a40-fs input pulse centered at 800 nm with energy up to 10.0 mJ can be compressed to a full width at half maximum(FWHM) of less than 5 fs after propagating through a neon-filled HCF with a length of 1 m and diameter of 500 μm with a transmission efficiency of 67%, which is significantly higher than that without a concentric phase mask. Pulses with energy up to 20.0 mJ can also be efficiently compressed to less than 10 fs with the concentric phase mask. The higher efficiency due to the concentric phase mask can be attributed to the redistribution of the transverse intensity profile, which reduces the effect of ionization. The proposed method exhibits great potential for generating few-cycle laser pulse sources with high energy by the HCF compressor.
基金Project supported by the National Natural Science Foundation of China(Grant No.61521093)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB16)+1 种基金the International S&T Cooperation Program of China(Grant No.2016YFE0119300)the Program of Shanghai Academic/Technology Research Leader,China(Grant No.18XD1404200)
文摘We perform a numerical study for temporally compressing radially-polarized（RP） infrared pulses in a gas-filled hollow-core fiber（HCF）. The dynamic transmission and nonlinear compression of RP pulses centered at wavelengths of0.8 m, 1.8 m, 3.1 m, and 5.0 m in HCFs are simulated. By comparing the propagation of pulses with the same optical cycles and intensity, we find that under proper conditions these pulses can be compressed down to 2–3 cycles. In the transverse direction, the spatiotemporal beam profile ameliorates from 0.8-m to 1.8-m and 3.1-m pulses before the appearance of high-order dispersion. These results show an alternative method of scaling generation for delivering RP infrared pulses in gas-filled HCFs, which can obtain energetic few-cycle pulses, and will be beneficial for relevant researches in the infrared scope.
文摘We numerically study the propagation dynamics of intense optical pulses in gas-filled hollow-core fibers（HCFs）. The spatiotemporal dynamics of the pulses show a transition from tightly confined to loosely confined characteristics as the fiber core is increased, which manifests as a deterioration in the spatiotemporal uniformity of the beam. It is found that using the gas pressure gradient does not enhance the beam quality in large-core HCFs, while inducing a positive chirp in the pulse to lower the peak power can improve the beam quality. This indicates that the self-focusing effect in the HCFs is the main driving force for the propagation dynamics. It also suggests that pulses at longer wavelengths are more suitable for HCFs with large cores because of the lower critical power of self-focusing, which is justified by the numerical simulations. These results will benefit the generation of energetic few-cycle pulses in large-core HCFs.
基金Project supported by the National Natural Science Foundation of China(Grant No.61925507)the National Key R&D Program of China(Grant No.2017YFE0123700)+5 种基金the Strategic Priority Research Program of Chinese Academic Sciences(Grant No.XDB1603)the Shanghai Municipal Science and Technology Major Project(Grant No.2017SHZDZX02)the Shanghai Natural ScienceFoundation(Grant No.20ZR1464600)the Program of Shanghai Academic/Technology Research Leader(Grant No.18XD1404200)the Shanghai Sailing Program(Grant No.21YF1453800)Youth Innovation Promotion Association of Chinese Academic Sciences(Grant No.Y202059).
文摘We present a cascaded nonlinear spectral broadening scheme for Nd-doped lasers,featuring with long pulse duration and high average power.This scheme is based on two multi-pass cells(MPCs)and one multiple-plate supercontinuum generation(MPSG),and the numerical investigation is driven by a home-made Nd-doped fiber laser with 12 ps pulse duration,50 kHz repetition rate and 100 W average power.The MPC-based first two stages allow us to broaden the pulse spectrum to 4 nm and 43 nm respectively,and subsequently,the MPSG-based third stage allows us to reach 235 nm spectral bandwidth.This broadened spectrum can support a Fourier-transfer-limited pulse duration of 9.8 fs,which is shorter than three optical cycles.To the best of our knowledge,it is the first time to demonstrate the possibility of few-cycle pulses generation based on the 10 ps level Nd-doped lasers.Such few-cycle and high average power laser sources should be attractive and prospective,benefiting from the characteristics of structure compact,low-cost and flexibility.
