Highly stable frequency-controlled optical frequency combs axe key elements of many applications in time- frequency and optical-metrology domains. In this work, we demonstrate a highly stable frequency-controlled erbi...Highly stable frequency-controlled optical frequency combs axe key elements of many applications in time- frequency and optical-metrology domains. In this work, we demonstrate a highly stable frequency-controlled erbium-fiber-based optical frequency comb system. Its repetition rate is phase-stabilized to a continuous-wave laser with both an intra-cavity electro-optic modulator and a piezo-transducer; while the carrier-envelope-offset frequency is phase-locked to a radio-frequency signal generator by controlling the pump power. In-loop relative frequency stabilities of the comb are below 1 ×10-16 at I s, and integrate down to low 10-2o level at 104 s. The corresponding timing uncertainties are 100-200 as over the full measurement range.展开更多
A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase microextxaodon （LPME） based on porous polypropylene hollow fibers in combination with on-line sweeping in micellar electr...A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase microextxaodon （LPME） based on porous polypropylene hollow fibers in combination with on-line sweeping in micellar electrokinodc chromatography was developed. The calibration curve was linear over the range of 20-200 ng mL^-1 for both strychnine and brucine in human urine sample. The detection limits （S/N = 3：1） for strychnine and brucine were 1 ng mL^-1 and 2 ng mL^-1, respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine samples.展开更多
The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 ...The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 × 10-13@1 s is employed for the light source. By using a periodically poled lithium niobate, the femtosecond pulse operating in 1556 nm is frequency-doubled to 778 nm to obtain the direct two-photon transition spectroscopy of thermal rubidium vapor. Through sweeping the carrier envelope offset frequency （fceo）, the 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition line is clearly resolved and its absolute frequency is determined via the peak-finding of the fitting curve. After the frequency correction, the measured result agrees well with the previous experiment on this transition. The entire potential candidate of optical frequency standard for system configuration is compact and robust, providing a telecommunication applications.展开更多
Potassium channels regulate diverse biological processes,ranging from cell proliferation to immune responses.However,the functions of potassium homeostasis and its regulatory mechanisms in adult stem cells and tumors ...Potassium channels regulate diverse biological processes,ranging from cell proliferation to immune responses.However,the functions of potassium homeostasis and its regulatory mechanisms in adult stem cells and tumors remain poorly characterized.Here,we identify Sandman(Sand),a two-pore-domain potassium channel in Drosophila melanogaster,as an essential regulator for the proliferation of intestinal stem cells and malignant tumors,while dispensable for the normal development processes.Mechanistically,loss of sand elevates intracellular K+concentration,leading to growth inhibition.This phenotype is rescued by pharmacological reduction of intracellular K+levels using the K+ionophore.Conversely,overexpression of sand triggers stem cell death in most regions of the midgut,inhibits tumor growth,and induces a Notch loss-of-function phenotype in the posterior midgut.These effects are mediated predominantly via the induction of endoplasmic reticulum(ER)stress,as demonstrated by the complete rescue of phenotypes through the co-expression of Ire1 or Xbp1s.Additionally,human homologues of Sand demonstrated similar ER stress-inducing capabilities,suggesting an evolutionarily conserved relationship between this channel and ER stress.Together,our findings identify Sand as a shared regulatory node that governs Drosophila adult stem cell dynamics and tumorigenesis through bioelectric homeostasis,and reveal a link between the two-pore potassium channel and ER stress signaling.展开更多
Objective:To assess the antitumor activity of the novel chitinase produced by fermented,isolated Trichoderma viride in a hepatocellular carcinoma(HCC)male rat model.Methods:Diethyl-nitrosamine induction combined with ...Objective:To assess the antitumor activity of the novel chitinase produced by fermented,isolated Trichoderma viride in a hepatocellular carcinoma(HCC)male rat model.Methods:Diethyl-nitrosamine induction combined with ionizing radiation exposure was used to establish the HCC rat model.All rats were divided into 4 groups:the control group,the chitinase group,the HCC group,and the HCC+chitinase group.The antiproliferative effect of chitinase was evaluated in human HCC cells.The effect of chitinase in vivo on oxidative stress,endoplasmic reticulum stress chaperones,autophagy markers,PI3K/AKT/mTOR,AMPK pathway expression,and apoptotic indicators was determined and confirmed by histological examination.Results:Chitinase significantly inhibited the viabilities of HepG2 cells.Moreover,in the Wistar male rat model of HCC,chitinase decreased ATP levels,modulated endoplasmic reticulum stress,mediated autophagy factors,and promoted apoptosis.Conclusions:Chitinase might play a role in the apoptosis as well as autophagy pathways and may act as a potential tumor suppressor.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 91336101 and 61127901the West Light Foundation of the Chinese Academy of Sciences under Grant No 2013ZD02
文摘Highly stable frequency-controlled optical frequency combs axe key elements of many applications in time- frequency and optical-metrology domains. In this work, we demonstrate a highly stable frequency-controlled erbium-fiber-based optical frequency comb system. Its repetition rate is phase-stabilized to a continuous-wave laser with both an intra-cavity electro-optic modulator and a piezo-transducer; while the carrier-envelope-offset frequency is phase-locked to a radio-frequency signal generator by controlling the pump power. In-loop relative frequency stabilities of the comb are below 1 ×10-16 at I s, and integrate down to low 10-2o level at 104 s. The corresponding timing uncertainties are 100-200 as over the full measurement range.
基金This work was supported both by the Natural Science Foundation of Hebei Province(B2006000413)the Scientific Research Foundation for the Returned 0verseas Chinese Scholars,State Education Ministry.
文摘A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase microextxaodon （LPME） based on porous polypropylene hollow fibers in combination with on-line sweeping in micellar electrokinodc chromatography was developed. The calibration curve was linear over the range of 20-200 ng mL^-1 for both strychnine and brucine in human urine sample. The detection limits （S/N = 3：1） for strychnine and brucine were 1 ng mL^-1 and 2 ng mL^-1, respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine samples.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61405002,91336103,10934010,61535001 and 61078026
文摘The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 × 10-13@1 s is employed for the light source. By using a periodically poled lithium niobate, the femtosecond pulse operating in 1556 nm is frequency-doubled to 778 nm to obtain the direct two-photon transition spectroscopy of thermal rubidium vapor. Through sweeping the carrier envelope offset frequency （fceo）, the 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition line is clearly resolved and its absolute frequency is determined via the peak-finding of the fitting curve. After the frequency correction, the measured result agrees well with the previous experiment on this transition. The entire potential candidate of optical frequency standard for system configuration is compact and robust, providing a telecommunication applications.
基金supported by the National Natural Science Foundation of China to L.H.(32470754 and 32070750)to X.M.(32170824 and 32322027)HRHl program of Westlake Laboratory of Life Sciences and Biomedicine to X.M.(1011103360222B1).
文摘Potassium channels regulate diverse biological processes,ranging from cell proliferation to immune responses.However,the functions of potassium homeostasis and its regulatory mechanisms in adult stem cells and tumors remain poorly characterized.Here,we identify Sandman(Sand),a two-pore-domain potassium channel in Drosophila melanogaster,as an essential regulator for the proliferation of intestinal stem cells and malignant tumors,while dispensable for the normal development processes.Mechanistically,loss of sand elevates intracellular K+concentration,leading to growth inhibition.This phenotype is rescued by pharmacological reduction of intracellular K+levels using the K+ionophore.Conversely,overexpression of sand triggers stem cell death in most regions of the midgut,inhibits tumor growth,and induces a Notch loss-of-function phenotype in the posterior midgut.These effects are mediated predominantly via the induction of endoplasmic reticulum(ER)stress,as demonstrated by the complete rescue of phenotypes through the co-expression of Ire1 or Xbp1s.Additionally,human homologues of Sand demonstrated similar ER stress-inducing capabilities,suggesting an evolutionarily conserved relationship between this channel and ER stress.Together,our findings identify Sand as a shared regulatory node that governs Drosophila adult stem cell dynamics and tumorigenesis through bioelectric homeostasis,and reveal a link between the two-pore potassium channel and ER stress signaling.
文摘Objective:To assess the antitumor activity of the novel chitinase produced by fermented,isolated Trichoderma viride in a hepatocellular carcinoma(HCC)male rat model.Methods:Diethyl-nitrosamine induction combined with ionizing radiation exposure was used to establish the HCC rat model.All rats were divided into 4 groups:the control group,the chitinase group,the HCC group,and the HCC+chitinase group.The antiproliferative effect of chitinase was evaluated in human HCC cells.The effect of chitinase in vivo on oxidative stress,endoplasmic reticulum stress chaperones,autophagy markers,PI3K/AKT/mTOR,AMPK pathway expression,and apoptotic indicators was determined and confirmed by histological examination.Results:Chitinase significantly inhibited the viabilities of HepG2 cells.Moreover,in the Wistar male rat model of HCC,chitinase decreased ATP levels,modulated endoplasmic reticulum stress,mediated autophagy factors,and promoted apoptosis.Conclusions:Chitinase might play a role in the apoptosis as well as autophagy pathways and may act as a potential tumor suppressor.
