Sialyltransferases （SlaTs） exist widely in vertebrates and play important roles in a variety of biological processes. In plants, several genes have also been identified to encode the proteins that share homology wit...Sialyltransferases （SlaTs） exist widely in vertebrates and play important roles in a variety of biological processes. In plants, several genes have also been identified to encode the proteins that share homology with the vertebrate SlaTs. However, very little is known about their functions in plants. Here we report the identification and characterization of a novel Arabidopsis gene, MALE GAMETOPHYTE DEFECTIVE 2 （MGP2） that encodes a sialyltransferase-like protein. MGP2 was expressed in all tissues including pollen grains and pollen tubes. The MGP2 protein was targeted to Golgi apparatus. Knockout of MGP2 significantly inhibited the pollen germination and retarded pollen tube growth in vitro and in vivo, but did not affect female gametophytic functions. These results suggest that the sialyltransferase-like protein MGP2 is important for normal pollen germination and pollen tube growth, giving a novel insight into the biological roles of the sialyltransferase.like proteins in plants.展开更多
The persistence infection of low-risk type （type 6 or type 11） of human papillomavirus （HPV） is the main cause of genital warts. Given the high rate of recurrence after treatment, the use of a new molecular agent ...The persistence infection of low-risk type （type 6 or type 11） of human papillomavirus （HPV） is the main cause of genital warts. Given the high rate of recurrence after treatment, the use of a new molecular agent is certain to be of value. The aim of this study was to achieve targeted inactivation of viral E7 gene in keratinocytes using the reprogrammed clustered regularly interspaced short palindromic repeats （CRISPR）/CRISPR-associated （Cas） 9 system. To accomplish this, a universal CRISPR-Cas9 system for targeting both HPV6/11 E7 genes was constructed by using a dual guide RNA vector. After transfection of the vector into E7-transfromed keratinocytes, the expression level of E7 protein was measured using western-blot analysis and the sequence of the E7 gene was determined using Sanger sequencing. Cell proliferation was analyzed by CCK-8 assay, and cell apoptosis was evaluated by Hoechst 33258 staining, flow cytometry analysis and ELISA assay. The results indicated that both HPV6/11 E7 genes can be inactivated by the single CRISPR-Cas9 system. Furthermore, silencing of E7 led to inhibition of cell proliferation and induction of apoptosis in E7-transfromed keratinocytes but not in normal keratinocytes. Our data suggested that the reprogrammed CRISPR-Cas9 system has the potential for the development of an adjuvant therapy for genital warts.展开更多
Complexation and interaction between silver and amino group were applied to induce an efficient immobilization of papain on silica spheres.Tbe silver nanoparticles were deposited on the silica spheres before p apainwa...Complexation and interaction between silver and amino group were applied to induce an efficient immobilization of papain on silica spheres.Tbe silver nanoparticles were deposited on the silica spheres before p apainwas coupled to the silica spheres. The silica spheres with silver nanoparticles were characterized by high resolution transmission electron microscopy （HR-TEM）, Fournier transform infrared spectroscopy （FT-IR）, and UV-Vis scanning spectrometer. FT-IR spectrum was also used to characterize the immobilized and free papain. Effect of some factors on the activities of the immobilized papain was investigated. It was observed that the coupled yield and relative activity of the papain on Ag/SiO2 were 1.17 and 1.86 times of those on the bare SiO2, respectively. At an optimum concentration of silver, theobserved activity of the immobilized papain was 2.1 timesof that on the bare.silica.In addition, the maximum specific activity of papain immobilized on Ag/SiO2 was 819.9 U·mg·^-1, which is slightly lower than that of the free papain, 906.2 U·mg^-1 . Stability of the immobilized papain was also examined. The resuits indicate that the silver nanoparticles successfully induce a fine immobilization of papain.展开更多
The MBT/CBT （Methylation Index of Branched Tetraethers/Cyclisation ratio of Branched Tetraether） proxy, a terrestrial paleothermometer based on bacterial branched glycerol dialkyl glycerol tetraethers CoGDGTs）, was...The MBT/CBT （Methylation Index of Branched Tetraethers/Cyclisation ratio of Branched Tetraether） proxy, a terrestrial paleothermometer based on bacterial branched glycerol dialkyl glycerol tetraethers CoGDGTs）, was employed to indicate altimetry; however, the mechanistic control on this proxy is still ambiguous. Here, we investigated the bGDGTs＇ distribution and associated environmental factors along an altitude transect of Mt. Shennongjia in China in order to determine the applicability of bGDGT-based proxies to altimetry reconstruction. The MBT index exhibits only a weak correlation with estimated mean annual air temperature （MATe, estimated according to the meteorological record and lapse rate） or altitude. Likewise, MBT shows weak or no relationship with temperature or altitude at four other mountains （Mts. Meghalaya, Jianfengling, Gongga, and Rungwe）. It is notable that mean annual air temperature （MAT） or altitude estimated by the MBT/CBT proxy largely relies on CBT, rather than on MBT, which was generally acknowledged. The poor relationship between MBT and MATe for Mt. Shennongjia can be ascribed to the insensitive response of bGDGT-I to temperature. Our data fxom this mountain imply that care should be taken if the MBT/CBT proxy is employed as an indication of paleoaltimetry. We propose that the fractional abundance of bGDGTs may be a better paleoaltimeter than the MBT/ CBT proxy, because specific bGDGT subsets that might show the most sensitive response to temperature can be preferentially selected using a statistical method and used to establish local calibration. This local calibration was applied to Mt. Shennongjia and apparently improves the accuracy of temperature and altimetry reconstruction. The differential response of bGDGTs to temperature among mountains suggests that local calibrations are needed to better constrain the altimetry.展开更多
The Inconel 718 alloy is widely used in the aerospace and power industries. The machining-induced surface integrity and fatigue life of this material are important factors for consideration due to high reliability and...The Inconel 718 alloy is widely used in the aerospace and power industries. The machining-induced surface integrity and fatigue life of this material are important factors for consideration due to high reliability and safety requirements. In this work, the milling of Inconel 718 was conducted at different cutting speeds and feed rates. Surface integrity and fatigue life were measured directly. The effects of cutting speed and feed rate on surface integrity and their further influences on fatigue life were analyzed. Within the chosen parameter range, the cutting speed barely affected the surface roughness, whereas the feed rate increased the surface roughness through the ideal residual height. The surface hardness increased as the cutting speed and feed rate increased. Tensile residual stress was observed on the machined surface, which showed improvement with the increasing feed rate. The cutting speed was not an influencing factor on fatigue life, but the feed rate affected fatigue life through the surface roughness. The high surface roughness resulting from the high feed rate could result in a high stress concentration factor and lead to a low fatigue life.展开更多
Cement raw meal with MSS and different heavy metals was blended to examine the fixation ratios, chemical species, and cement crystalline phases in clinkers. The results showed that blending MSS could decrease the fixa...Cement raw meal with MSS and different heavy metals was blended to examine the fixation ratios, chemical species, and cement crystalline phases in clinkers. The results showed that blending MSS could decrease the fixation ratio of Cr, Ni, Cu, and Zn in the produced clinker by 5% to 25%. And Cr, Cu, and Zn were mainly incorporated into clinkers as metal silicates, Ni was mainly solubilized in Mg O to form magnesium nickel oxides, and the transition phases were mainly metal aluminum oxides as indicated by X-ray diffraction. The reduction of fixation ratios was likely attributed to the presence of impure elements, such as sodium and phosphorus in MSS. In addition, high concentrations（eg, 1.7 wt%） of chlorine in MSS led to metal chloride formation that could vaporize Cu, Cr, Ni, and Zn. To summarize, introducing MSS would decrease the fixation ratios of heavy metals due to the presence of impure elements, such as sodium and phosphorus and chlorine.展开更多
Introduction:Human prion diseases(PrDs)are rare,fatal encephalopathies requiring comprehensive diagnostic analysis.This study examines hospital referral patterns to the Chinese National Surveillance for Creutzfeldt-Ja...Introduction:Human prion diseases(PrDs)are rare,fatal encephalopathies requiring comprehensive diagnostic analysis.This study examines hospital referral patterns to the Chinese National Surveillance for Creutzfeldt-Jakob Disease(CNS-CJD)from 2006 to 2019.Methods:We assessed 1,970 PrD cases referred by various hospitals to CNS-CJD.Referral distributions were analyzed based on provincial-level administrative divisions(PLADs).Differences in referral numbers and confirmed cases between monitored and nonmonitored PLADs were statistically evaluated.Results:The study included cases from 344 hospitals across 29 Chinese PLADs.Hospital referrals increased over the surveillance years:from 28.2 hospitals annually during 2006–2010,to 64 in 2011–2015,and 107 in 2016–2019.Of these,12.2%(42/344)of hospitals reported≥10 PrD cases,accounting for 70.0%(1,379/1,970)of total cases.Referral numbers varied across PLADs,with the top 5 of Beijing(41),Henan(26),Shanghai(21),Guangdong(21),and Jiangsu(21)leading.Additionally,12 CJD-surveillance PLADs had more referring hospitals and PrD cases than the other 17 non-surveillance PLADs.Conclusions:Geographical variations in PrD recognition exist across Chinese PLADs,with certain regions and major cities reporting notably higher case numbers.展开更多
Mixed solvent of 1-octanol and cyclohexane with 60% （by mass） 1-octanol content was selected as a new extractant for caprolactam extraction. Compared with benzene or toluene, the new extractant has larger extraction...Mixed solvent of 1-octanol and cyclohexane with 60% （by mass） 1-octanol content was selected as a new extractant for caprolactam extraction. Compared with benzene or toluene, the new extractant has larger extraction capacity and much lower toxicity. Although the extraction capacity of the new extractant is smaller than that of pure 1-octanol, 1-octanol solubility of the new extractant in aqueous phase is much smaller. Because of its physical properties of lower density, lower viscosity, and higher interfacial tension, the new extractant performed much better phase separation ability than pure 1-octanol. The new extractant showed certain selectivity when dealing with lactam oil. The mixed solvent of 1-octanol and cyclohexane with 60% （by mass） 1-octanol content is a promising extractant for caprolactam extraction.展开更多
Activated carbon-supported Ru-based catalyst and A301 iron catalyst were prepared,and the influences of reaction temperature,space velocity,pressure,and H2/N2 ratio on performance of iron catalyst coupled with Ru cata...Activated carbon-supported Ru-based catalyst and A301 iron catalyst were prepared,and the influences of reaction temperature,space velocity,pressure,and H2/N2 ratio on performance of iron catalyst coupled with Ru catalyst in series for ammonia synthesis were investigated.The activity tests were also performed on the single Ru and Fe catalysts as comparison.Results showed that the activity of the Ru catalyst for ammonia synthesis was higher than that of the iron catalyst by 33.5%-37.6% under the reaction conditions：375-400 °C,10 MPa,10000 h-1,H2︰N2 3,and the Ru catalyst also had better thermal stability when treated at 475 °C for 20 h.The outlet ammonia concentration using Fe-Ru catalyst was increased by 45.6%-63.5% than that of the single-iron catalyst at low tem-perature （375-400 °C）,and the outlet ammonia concentration increased with increasing Ru catalyst loading.展开更多
The triangular-lattice highly birefringent photonic crystal fibers(PCFs) with gradually increasing diameter of the air holes along radial axis are put forward. The modal birefringence, dispersion and confinement loss ...The triangular-lattice highly birefringent photonic crystal fibers(PCFs) with gradually increasing diameter of the air holes along radial axis are put forward. The modal birefringence, dispersion and confinement loss of the fundamental mode are simulated by full vector Galerkin finite element method(FEM) with a perfectly matched layer(PML). The results show that this PCF can keep low confinement loss when the rings of air holes are few. When the wavelength is 1.55 μm , the birefringence, the confinement loss of quick-axis and slow-axis are 1.365×10-3, 0.017 dB/m and 0.051 dB/m, respectively. A new way is proposed to fabricate polarization-mainting fibers with high performance.展开更多
A simple and stable loop consisting of a pair of concatenated electroabsorption modulators （EAMs） and 10 GHz clock recovery module is presented and demonstrated experimentally for simultaneous demultiplexing and clo...A simple and stable loop consisting of a pair of concatenated electroabsorption modulators （EAMs） and 10 GHz clock recovery module is presented and demonstrated experimentally for simultaneous demultiplexing and clock recovery for OTDM networks. The 10 Gb/s demultiplexed signal and 10 GHz recovered clock are successfully implemented from 80 Gbit/s and 160 Gbit/s OTDM signals utilizing the loop. The loop based on EAM-PLL can provide excellent tolerance range （〉 5 dB） of the OSCR of the source laser, and the recovered clock signal exhibits low rms jitter over a dynamic input optical power range of 15 dB.展开更多
Recently, the North American Nanohertz Observatory for Gravitational Waves(NANOGrav) claimed the detection of a stochastic common-spectrum process of the pulsar timing array(PTA) time residuals from their 12.5 year da...Recently, the North American Nanohertz Observatory for Gravitational Waves(NANOGrav) claimed the detection of a stochastic common-spectrum process of the pulsar timing array(PTA) time residuals from their 12.5 year data, which might be the first detection of the stochastic background of gravitational waves(GWs). We show that the amplitude and the power index of such waves imply that they could be the secondary GWs induced by the peaked curvature perturbation with a dust-like post inflationary era with-0.091 ≤ w ≤ 0.048. Such stochastic background of GWs naturally predicts substantial existence of planet-mass primordial black holes(PBHs), which can be the lensing objects for the ultrashort-timescale microlensing events observed by the Optical Gravitational Lensing Experiment(OGLE).展开更多
In order to investigate the optimal foam dyeing process and the compatibility of trichromatic reactive dyes in foam dyeing,varying proportions of ternary mixtures of Remazol Red RGB,Remazol Yellow RGB and Remazol Navy...In order to investigate the optimal foam dyeing process and the compatibility of trichromatic reactive dyes in foam dyeing,varying proportions of ternary mixtures of Remazol Red RGB,Remazol Yellow RGB and Remazol Navy RGB have been used to dye bleached cotton fabric.The results showed that,the optimal dyeing condition in foam dyeing was alkaline agent 15 g/L,stabilizers 0.7g/L,blow ratio 8,and steaming time 1.5 min,respectively.Compared with conventional pad-dyeing,color strength and fixation rate of dyed fabric were higher than those of conventional paddyeing,the dyed fabric had the same washing and rubbing fastness as conventional pad-dyeing and the color shade of dyed fabric was different from that of conventional pad-dyeing.The color triangle,which consisted of 66 dyed fabric samples dyed with trichromatic reactive dyes in different proportions,could provide foundation for computer colorant formulation of the color matching system.展开更多
In 2007, Dr. Jia-Xiang Shen received the ＂Outstanding Contribution Award＂ at the centenary celebrations of Chinese Pharmaceutical Association. Dr. Shen was acknowledged for his study on the new methodology for the t...In 2007, Dr. Jia-Xiang Shen received the ＂Outstanding Contribution Award＂ at the centenary celebrations of Chinese Pharmaceutical Association. Dr. Shen was acknowledged for his study on the new methodology for the total synthesis of chloramphenicol, the industrialization of several important steroid hormone drugs, and for being a co-founder of Chinese modern pharmaceutical industry.展开更多
Si/Gesuperlattices are promising thermoelec- tric materials to convert thermal energy into electric power. The nanoscale thermal transport in Si/Gesuperlattices is investigated via molecular dynamics （MD） simulation...Si/Gesuperlattices are promising thermoelec- tric materials to convert thermal energy into electric power. The nanoscale thermal transport in Si/Gesuperlattices is investigated via molecular dynamics （MD） simulation in this short communication. The impact of Si and Ge interface on the cross-plane thermal conductivity reduction in the Si/Gesuperlattices is studied by designing cone- structured interface and aperiodicity between the Si and Ge layers. The temperature difference between the left and right sides of the Si/Gesuperlattices is set up for none- quilibrium MD simulation. The spatial distribution of temperature is recorded to examine whether the steady- state has been reached. As a crucial factor to quantify thermal transport, the temporal evolution of heat flux flowing through Si/Gesuperlattices is calculated. Com- pared with the even interface, the cone-structured interface contributes remarkable resistance to the thermal transport, whereas the aperiodic arrangement of Si and Ge layers with unequal thicknesses has a marginal influence on the reduction of effective thermal conductivity. The interface with divergent cone-structure shows the most excellent performance of all the simulated cases, which brings a 33% reduction of the average thermal conductivity to the other Si/Gesuperlattices with even, convergent cone-structured interfaces and aperiodic arrangements. The design of divergent cone-structured interface sheds promising lighton enhancing the thermoelectric efficiency of Si/Ge based materials.展开更多
A simple clock enhanced loop of cascaded electro-absorption modulators （EAMs） and 10 GHz clock recovery modules is presented. The intensity of harmonic of clock-frequency component is analyzed theoretically and veri...A simple clock enhanced loop of cascaded electro-absorption modulators （EAMs） and 10 GHz clock recovery modules is presented. The intensity of harmonic of clock-frequency component is analyzed theoretically and verified experimentally in a 160 Gb/s OTDM 100 km transmission system. The 10 GHz clock component is enhanced obviously before launching into the clock recovery module and the recovered clock signal exhibits low rms jitter of 〈400 fs. Moreover, completely error^-1free （10-12） transmission is observed for more than two hours without using forward error correction technology. The power penalty is about 3.6 dB. The proposed loop has merits of enhancing base clock component, simultaneously de-multiplexing and clock recovery, which make the performance of this loop more stable and high suppression of non-target channels.展开更多
Using LYSO scintillator coupled on HAMAMATSU R9800 （a fast photomultiplier） to form the small size γ-ray detectors, a compact lifetime spectrometer has been built for the positron annihilation experiments. The syst...Using LYSO scintillator coupled on HAMAMATSU R9800 （a fast photomultiplier） to form the small size γ-ray detectors, a compact lifetime spectrometer has been built for the positron annihilation experiments. The system time resolution FWHM=193 ps and the coincidence counting rate -8 cps/p.Ci were achieved. A lifetime value of 219±1 ps of positron annihilation in well annealed Si was tested, which is in agreement with the typical values published in the previous lectures.展开更多
Neuroglobin (NGB) is a newly discov- ered member of the hemoglobin superfamily that is primarily expressed in the brain of humans and other vertebrates. The effects of protein concentration, solvent, pH and temperatur...Neuroglobin (NGB) is a newly discov- ered member of the hemoglobin superfamily that is primarily expressed in the brain of humans and other vertebrates. The effects of protein concentration, solvent, pH and temperature on the secondary structure of NGB were investigated by employing far UV circular dichroism (CD) spectroscopy. The results show that NGB exists mainly in α-helix form when its concentration is less than 10 μmol/L. However, its α-helix content decreases with the increase of con- centration in the range of 10―40 μmol/L and remains unchanged when the concentration is higher than 40 μmol/L, which suggest that NGBs form intermolecular disulfide bond and aggregate in higher concentration. The α-helix content of NGB in methanol and ethanol is a little higher than that in water, indicating a higher stability of NGB in these solvents. NGB loses its α-helical secondary structure in either acidic or alka- line solution to some extent. Although increased temperature destabilizes the α-helices of NGB, over 16% of α-helices can be kept at 110°C. Therefore, NGB is a protein with hyperthermal stability.展开更多
基金supported by the research grants from the National Natural Science Foundation of China(30530060)State Key Basic Research and Development Plan of China(2007CB108700)the Ministry of Education (111 project B06003)
文摘Sialyltransferases （SlaTs） exist widely in vertebrates and play important roles in a variety of biological processes. In plants, several genes have also been identified to encode the proteins that share homology with the vertebrate SlaTs. However, very little is known about their functions in plants. Here we report the identification and characterization of a novel Arabidopsis gene, MALE GAMETOPHYTE DEFECTIVE 2 （MGP2） that encodes a sialyltransferase-like protein. MGP2 was expressed in all tissues including pollen grains and pollen tubes. The MGP2 protein was targeted to Golgi apparatus. Knockout of MGP2 significantly inhibited the pollen germination and retarded pollen tube growth in vitro and in vivo, but did not affect female gametophytic functions. These results suggest that the sialyltransferase-like protein MGP2 is important for normal pollen germination and pollen tube growth, giving a novel insight into the biological roles of the sialyltransferase.like proteins in plants.
文摘The persistence infection of low-risk type （type 6 or type 11） of human papillomavirus （HPV） is the main cause of genital warts. Given the high rate of recurrence after treatment, the use of a new molecular agent is certain to be of value. The aim of this study was to achieve targeted inactivation of viral E7 gene in keratinocytes using the reprogrammed clustered regularly interspaced short palindromic repeats （CRISPR）/CRISPR-associated （Cas） 9 system. To accomplish this, a universal CRISPR-Cas9 system for targeting both HPV6/11 E7 genes was constructed by using a dual guide RNA vector. After transfection of the vector into E7-transfromed keratinocytes, the expression level of E7 protein was measured using western-blot analysis and the sequence of the E7 gene was determined using Sanger sequencing. Cell proliferation was analyzed by CCK-8 assay, and cell apoptosis was evaluated by Hoechst 33258 staining, flow cytometry analysis and ELISA assay. The results indicated that both HPV6/11 E7 genes can be inactivated by the single CRISPR-Cas9 system. Furthermore, silencing of E7 led to inhibition of cell proliferation and induction of apoptosis in E7-transfromed keratinocytes but not in normal keratinocytes. Our data suggested that the reprogrammed CRISPR-Cas9 system has the potential for the development of an adjuvant therapy for genital warts.
基金Supported by the National High Technology Research and Development Program of China （2006AA02Z211）, the National Natural Science Foundation of China （20376034）, the Natural Science Foundation of Jiangsu Province （BK2006181）, and the Foundation of Jiangsu Province for College Postgraduate Students in Innovation Engineering （2007）.
文摘Complexation and interaction between silver and amino group were applied to induce an efficient immobilization of papain on silica spheres.Tbe silver nanoparticles were deposited on the silica spheres before p apainwas coupled to the silica spheres. The silica spheres with silver nanoparticles were characterized by high resolution transmission electron microscopy （HR-TEM）, Fournier transform infrared spectroscopy （FT-IR）, and UV-Vis scanning spectrometer. FT-IR spectrum was also used to characterize the immobilized and free papain. Effect of some factors on the activities of the immobilized papain was investigated. It was observed that the coupled yield and relative activity of the papain on Ag/SiO2 were 1.17 and 1.86 times of those on the bare SiO2, respectively. At an optimum concentration of silver, theobserved activity of the immobilized papain was 2.1 timesof that on the bare.silica.In addition, the maximum specific activity of papain immobilized on Ag/SiO2 was 819.9 U·mg·^-1, which is slightly lower than that of the free papain, 906.2 U·mg^-1 . Stability of the immobilized papain was also examined. The resuits indicate that the silver nanoparticles successfully induce a fine immobilization of papain.
文摘The MBT/CBT （Methylation Index of Branched Tetraethers/Cyclisation ratio of Branched Tetraether） proxy, a terrestrial paleothermometer based on bacterial branched glycerol dialkyl glycerol tetraethers CoGDGTs）, was employed to indicate altimetry; however, the mechanistic control on this proxy is still ambiguous. Here, we investigated the bGDGTs＇ distribution and associated environmental factors along an altitude transect of Mt. Shennongjia in China in order to determine the applicability of bGDGT-based proxies to altimetry reconstruction. The MBT index exhibits only a weak correlation with estimated mean annual air temperature （MATe, estimated according to the meteorological record and lapse rate） or altitude. Likewise, MBT shows weak or no relationship with temperature or altitude at four other mountains （Mts. Meghalaya, Jianfengling, Gongga, and Rungwe）. It is notable that mean annual air temperature （MAT） or altitude estimated by the MBT/CBT proxy largely relies on CBT, rather than on MBT, which was generally acknowledged. The poor relationship between MBT and MATe for Mt. Shennongjia can be ascribed to the insensitive response of bGDGT-I to temperature. Our data fxom this mountain imply that care should be taken if the MBT/CBT proxy is employed as an indication of paleoaltimetry. We propose that the fractional abundance of bGDGTs may be a better paleoaltimeter than the MBT/ CBT proxy, because specific bGDGT subsets that might show the most sensitive response to temperature can be preferentially selected using a statistical method and used to establish local calibration. This local calibration was applied to Mt. Shennongjia and apparently improves the accuracy of temperature and altimetry reconstruction. The differential response of bGDGTs to temperature among mountains suggests that local calibrations are needed to better constrain the altimetry.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant No. 51675312）, a Project of Shandong Province Higher Educational Science and Technology Program （Grant No. J ITKZ001）, and the Key Laboratory of High-efficiency and Clean Mechanical Manufacture at Shandong University, Ministry of Education.
文摘The Inconel 718 alloy is widely used in the aerospace and power industries. The machining-induced surface integrity and fatigue life of this material are important factors for consideration due to high reliability and safety requirements. In this work, the milling of Inconel 718 was conducted at different cutting speeds and feed rates. Surface integrity and fatigue life were measured directly. The effects of cutting speed and feed rate on surface integrity and their further influences on fatigue life were analyzed. Within the chosen parameter range, the cutting speed barely affected the surface roughness, whereas the feed rate increased the surface roughness through the ideal residual height. The surface hardness increased as the cutting speed and feed rate increased. Tensile residual stress was observed on the machined surface, which showed improvement with the increasing feed rate. The cutting speed was not an influencing factor on fatigue life, but the feed rate affected fatigue life through the surface roughness. The high surface roughness resulting from the high feed rate could result in a high stress concentration factor and lead to a low fatigue life.
基金the National Major Science and Technology Project of Water Pollution Control and Management,China(No.2010ZX07319-001-02)
文摘Cement raw meal with MSS and different heavy metals was blended to examine the fixation ratios, chemical species, and cement crystalline phases in clinkers. The results showed that blending MSS could decrease the fixation ratio of Cr, Ni, Cu, and Zn in the produced clinker by 5% to 25%. And Cr, Cu, and Zn were mainly incorporated into clinkers as metal silicates, Ni was mainly solubilized in Mg O to form magnesium nickel oxides, and the transition phases were mainly metal aluminum oxides as indicated by X-ray diffraction. The reduction of fixation ratios was likely attributed to the presence of impure elements, such as sodium and phosphorus in MSS. In addition, high concentrations（eg, 1.7 wt%） of chlorine in MSS led to metal chloride formation that could vaporize Cu, Cr, Ni, and Zn. To summarize, introducing MSS would decrease the fixation ratios of heavy metals due to the presence of impure elements, such as sodium and phosphorus and chlorine.
基金Supported by the Grant(2021SKLID101,2019SKLID603)the State Key Laboratory for Infectious Disease Prevention and Control,China CDC.
文摘Introduction:Human prion diseases(PrDs)are rare,fatal encephalopathies requiring comprehensive diagnostic analysis.This study examines hospital referral patterns to the Chinese National Surveillance for Creutzfeldt-Jakob Disease(CNS-CJD)from 2006 to 2019.Methods:We assessed 1,970 PrD cases referred by various hospitals to CNS-CJD.Referral distributions were analyzed based on provincial-level administrative divisions(PLADs).Differences in referral numbers and confirmed cases between monitored and nonmonitored PLADs were statistically evaluated.Results:The study included cases from 344 hospitals across 29 Chinese PLADs.Hospital referrals increased over the surveillance years:from 28.2 hospitals annually during 2006–2010,to 64 in 2011–2015,and 107 in 2016–2019.Of these,12.2%(42/344)of hospitals reported≥10 PrD cases,accounting for 70.0%(1,379/1,970)of total cases.Referral numbers varied across PLADs,with the top 5 of Beijing(41),Henan(26),Shanghai(21),Guangdong(21),and Jiangsu(21)leading.Additionally,12 CJD-surveillance PLADs had more referring hospitals and PrD cases than the other 17 non-surveillance PLADs.Conclusions:Geographical variations in PrD recognition exist across Chinese PLADs,with certain regions and major cities reporting notably higher case numbers.
基金Supported by the National Natural Science Foundation of China （20490200, 20525622） and the National Basic Research Program of China （2007CB714302）.
文摘Mixed solvent of 1-octanol and cyclohexane with 60% （by mass） 1-octanol content was selected as a new extractant for caprolactam extraction. Compared with benzene or toluene, the new extractant has larger extraction capacity and much lower toxicity. Although the extraction capacity of the new extractant is smaller than that of pure 1-octanol, 1-octanol solubility of the new extractant in aqueous phase is much smaller. Because of its physical properties of lower density, lower viscosity, and higher interfacial tension, the new extractant performed much better phase separation ability than pure 1-octanol. The new extractant showed certain selectivity when dealing with lactam oil. The mixed solvent of 1-octanol and cyclohexane with 60% （by mass） 1-octanol content is a promising extractant for caprolactam extraction.
基金Supported by the National Natural Science Foundation of China（20803064） the Natural Science Foundation of Zhejiang Province（Y409034）
文摘Activated carbon-supported Ru-based catalyst and A301 iron catalyst were prepared,and the influences of reaction temperature,space velocity,pressure,and H2/N2 ratio on performance of iron catalyst coupled with Ru catalyst in series for ammonia synthesis were investigated.The activity tests were also performed on the single Ru and Fe catalysts as comparison.Results showed that the activity of the Ru catalyst for ammonia synthesis was higher than that of the iron catalyst by 33.5%-37.6% under the reaction conditions：375-400 °C,10 MPa,10000 h-1,H2︰N2 3,and the Ru catalyst also had better thermal stability when treated at 475 °C for 20 h.The outlet ammonia concentration using Fe-Ru catalyst was increased by 45.6%-63.5% than that of the single-iron catalyst at low tem-perature （375-400 °C）,and the outlet ammonia concentration increased with increasing Ru catalyst loading.
基金National Natural Science Foundation of China(No.60577034)
文摘The triangular-lattice highly birefringent photonic crystal fibers(PCFs) with gradually increasing diameter of the air holes along radial axis are put forward. The modal birefringence, dispersion and confinement loss of the fundamental mode are simulated by full vector Galerkin finite element method(FEM) with a perfectly matched layer(PML). The results show that this PCF can keep low confinement loss when the rings of air holes are few. When the wavelength is 1.55 μm , the birefringence, the confinement loss of quick-axis and slow-axis are 1.365×10-3, 0.017 dB/m and 0.051 dB/m, respectively. A new way is proposed to fabricate polarization-mainting fibers with high performance.
基金Supported by and the National High-Tech Research and Development Program of China under Grant Nos 2007AA01Z258 and 2008AA01Z15, the National Natural Science Foundation of China under Grant Nos 60577034, 60747002 and 60877042, the Excellent Doctoral Scientific Innovation Projects of Beijing Jiaotong University under Grant No 141051522, and the National Science Foundations of Beijing under Grant No 4062027.
文摘A simple and stable loop consisting of a pair of concatenated electroabsorption modulators （EAMs） and 10 GHz clock recovery module is presented and demonstrated experimentally for simultaneous demultiplexing and clock recovery for OTDM networks. The 10 Gb/s demultiplexed signal and 10 GHz recovered clock are successfully implemented from 80 Gbit/s and 160 Gbit/s OTDM signals utilizing the loop. The loop based on EAM-PLL can provide excellent tolerance range （〉 5 dB） of the OSCR of the source laser, and the recovered clock signal exhibits low rms jitter over a dynamic input optical power range of 15 dB.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFC2201502)supported by the European Union’s Horizon 2020 Research and Innovation Program under the Marie Sk?odowska-Curie(Grant No.754496)+4 种基金supported by the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB15)the Chinese Academy of Sciences Project for Young Scientists in Basic Research(Grant No.YSBR-006)the National Natural Science Foundation of China(Grant No.12047503)the Japan Society for the Promotion of Science Grant-in-Aid for Early-Career Scientists(Grant No.JP20K14461)the World Premier International Research Center Initiative(WPI Initiative),MEXT,Japan。
文摘Recently, the North American Nanohertz Observatory for Gravitational Waves(NANOGrav) claimed the detection of a stochastic common-spectrum process of the pulsar timing array(PTA) time residuals from their 12.5 year data, which might be the first detection of the stochastic background of gravitational waves(GWs). We show that the amplitude and the power index of such waves imply that they could be the secondary GWs induced by the peaked curvature perturbation with a dust-like post inflationary era with-0.091 ≤ w ≤ 0.048. Such stochastic background of GWs naturally predicts substantial existence of planet-mass primordial black holes(PBHs), which can be the lensing objects for the ultrashort-timescale microlensing events observed by the Optical Gravitational Lensing Experiment(OGLE).
文摘In order to investigate the optimal foam dyeing process and the compatibility of trichromatic reactive dyes in foam dyeing,varying proportions of ternary mixtures of Remazol Red RGB,Remazol Yellow RGB and Remazol Navy RGB have been used to dye bleached cotton fabric.The results showed that,the optimal dyeing condition in foam dyeing was alkaline agent 15 g/L,stabilizers 0.7g/L,blow ratio 8,and steaming time 1.5 min,respectively.Compared with conventional pad-dyeing,color strength and fixation rate of dyed fabric were higher than those of conventional paddyeing,the dyed fabric had the same washing and rubbing fastness as conventional pad-dyeing and the color shade of dyed fabric was different from that of conventional pad-dyeing.The color triangle,which consisted of 66 dyed fabric samples dyed with trichromatic reactive dyes in different proportions,could provide foundation for computer colorant formulation of the color matching system.
文摘In 2007, Dr. Jia-Xiang Shen received the ＂Outstanding Contribution Award＂ at the centenary celebrations of Chinese Pharmaceutical Association. Dr. Shen was acknowledged for his study on the new methodology for the total synthesis of chloramphenicol, the industrialization of several important steroid hormone drugs, and for being a co-founder of Chinese modern pharmaceutical industry.
文摘Si/Gesuperlattices are promising thermoelec- tric materials to convert thermal energy into electric power. The nanoscale thermal transport in Si/Gesuperlattices is investigated via molecular dynamics （MD） simulation in this short communication. The impact of Si and Ge interface on the cross-plane thermal conductivity reduction in the Si/Gesuperlattices is studied by designing cone- structured interface and aperiodicity between the Si and Ge layers. The temperature difference between the left and right sides of the Si/Gesuperlattices is set up for none- quilibrium MD simulation. The spatial distribution of temperature is recorded to examine whether the steady- state has been reached. As a crucial factor to quantify thermal transport, the temporal evolution of heat flux flowing through Si/Gesuperlattices is calculated. Com- pared with the even interface, the cone-structured interface contributes remarkable resistance to the thermal transport, whereas the aperiodic arrangement of Si and Ge layers with unequal thicknesses has a marginal influence on the reduction of effective thermal conductivity. The interface with divergent cone-structure shows the most excellent performance of all the simulated cases, which brings a 33% reduction of the average thermal conductivity to the other Si/Gesuperlattices with even, convergent cone-structured interfaces and aperiodic arrangements. The design of divergent cone-structured interface sheds promising lighton enhancing the thermoelectric efficiency of Si/Ge based materials.
基金Supported by the Fundamental Research Funds for the Central Universities （No 2009YJS005）, the National High-Tech Research and Development Program of China under Grant No 2008AA01Z15, the National Natural Science Foundation of China under Grant No 60877042 and 60837003, Beijing Nova Program （No 2008A026）, and the Natural Science Foundation of Beijing （No 4062027）.
文摘A simple clock enhanced loop of cascaded electro-absorption modulators （EAMs） and 10 GHz clock recovery modules is presented. The intensity of harmonic of clock-frequency component is analyzed theoretically and verified experimentally in a 160 Gb/s OTDM 100 km transmission system. The 10 GHz clock component is enhanced obviously before launching into the clock recovery module and the recovered clock signal exhibits low rms jitter of 〈400 fs. Moreover, completely error^-1free （10-12） transmission is observed for more than two hours without using forward error correction technology. The power penalty is about 3.6 dB. The proposed loop has merits of enhancing base clock component, simultaneously de-multiplexing and clock recovery, which make the performance of this loop more stable and high suppression of non-target channels.
基金Supported by Natural Science Foundation of China (10775149,10805049)
文摘Using LYSO scintillator coupled on HAMAMATSU R9800 （a fast photomultiplier） to form the small size γ-ray detectors, a compact lifetime spectrometer has been built for the positron annihilation experiments. The system time resolution FWHM=193 ps and the coincidence counting rate -8 cps/p.Ci were achieved. A lifetime value of 219±1 ps of positron annihilation in well annealed Si was tested, which is in agreement with the typical values published in the previous lectures.
基金This work was supported by the National Natural Science Foundation of China(Grant No.20471025).
文摘Neuroglobin (NGB) is a newly discov- ered member of the hemoglobin superfamily that is primarily expressed in the brain of humans and other vertebrates. The effects of protein concentration, solvent, pH and temperature on the secondary structure of NGB were investigated by employing far UV circular dichroism (CD) spectroscopy. The results show that NGB exists mainly in α-helix form when its concentration is less than 10 μmol/L. However, its α-helix content decreases with the increase of con- centration in the range of 10―40 μmol/L and remains unchanged when the concentration is higher than 40 μmol/L, which suggest that NGBs form intermolecular disulfide bond and aggregate in higher concentration. The α-helix content of NGB in methanol and ethanol is a little higher than that in water, indicating a higher stability of NGB in these solvents. NGB loses its α-helical secondary structure in either acidic or alka- line solution to some extent. Although increased temperature destabilizes the α-helices of NGB, over 16% of α-helices can be kept at 110°C. Therefore, NGB is a protein with hyperthermal stability.
