The magnetic behavior of a two-electron quantum dot/ring system is analytically studied with electron-electron(e-e)interaction taking into account the Rashba spin-orbit interaction(SOI)and magnetic field.The Jacobi tr...The magnetic behavior of a two-electron quantum dot/ring system is analytically studied with electron-electron(e-e)interaction taking into account the Rashba spin-orbit interaction(SOI)and magnetic field.The Jacobi transformation has been employed to separate the Hamiltonian of the system to the center of mass and relative terms.The Schrödinger equation is analytically solved,and energy spectra are obtained.Then,the magnetization and susceptibility are calculated.The magnetization decreases by raising the magnetic field without and with SOI,and also without e-e interaction.Also,the SOI slightly modifies the magnetization of the system without e-e interaction.The susceptibility displays a peak structure as the magnetic field changes from low values to high values.The susceptibility by considering e-e interaction and without the SOI is always negative and its value decreases by rising the magnetic field.The susceptibility displays a transition from diamagnetic to paramagnetic with e-e interaction and SOI.展开更多
High catalytic efficiencies in ring opening polymerization(ROP)of a large ring-sized macrolactone,ω-pentadecalactone(PDL),by using transition metal Fe(II)-based catalysts were achieved for the first time in this stud...High catalytic efficiencies in ring opening polymerization(ROP)of a large ring-sized macrolactone,ω-pentadecalactone(PDL),by using transition metal Fe(II)-based catalysts were achieved for the first time in this study.Benefited from the bulky nature of the ligatedα-diimine ligands,as evidenced from single-crystal structures,as well as the weakly oxophilic nature of the metal centers,chain transesterification reactions could be partially suppressed,allowing the polymerization proceed in a living-like and semi-controllable manner,i.e.good linear dependence of propagation rates on catalyst concentration and PDL concentration as observed in the detailed kinetics studies.The whole polymerization proceeds via a“coordination-insertion”mechanism,and with the aid of density functional theory(DFT)calculation studies,a“slow insertion→fast elimination”manner was demonstrated for the monomer propagation step,suggesting the insertion of Fe-OR into the carbonyl group C=O as the rate-determining step.The present catalytic system also showed fast chain transfer reactions to alcohol compounds,affording quasi-immortal characteristics.DFT calculations showed that such a transfer reaction only required an energy barrier of 6.4 kcal/mol,performing a good consistency with the fast chain transfer rates.展开更多
To address the installation challenges of a 2-m ring Gregorian telescope system,and similar optical systems with a small width-to-radius ratio,we propose a detection method combining local interferometry with a compar...To address the installation challenges of a 2-m ring Gregorian telescope system,and similar optical systems with a small width-to-radius ratio,we propose a detection method combining local interferometry with a comparison model.This method enhances the precision of system calibration by establishing a dataset that delineates the relationship between secondary mirror misalignment and wavefront aberration,subsequently inferring the misalignment from interferometric detection results during the calibration process.For the 2-m ring telescope,we develop a detection model using five local sub-apertures,enabling a root-mean-square detection accuracy of 0:0225λ(λ=632:8 nm)for full-aperture wavefront aberration.The calibration results for the 2-m Ring Solar Telescope system indicate that the root-mean-square value of sub-aperture wavefront aberration reaches 0.104λ,and the root-mean-square value of spliced full-aperture measurement yields reaches 0.112λ.This method offers a novel approach for calibrating small width-toradius ratio telescope systems and can be applied to the calibration of other irregular-aperture optical systems.展开更多
High pressure enables the creation of novel functional materials by modifying chemical bonding and crystal structure,opening avenues for the development of high-energy-density polynitrogen materials.We present the hig...High pressure enables the creation of novel functional materials by modifying chemical bonding and crystal structure,opening avenues for the development of high-energy-density polynitrogen materials.We present the high-pressure synthesis of three polynitrides P1 AgN7,P21/c AgN5,and P-1 AgN4,achieved through direct reactions between silver and nitrogen.Notably,the synthesis pressures required for the formation of N5 and N6 rings from metal–nitrogen reactions in this work represent the lowest values reported to date in high-pressure studies.At 15 GPa,isolated N5 rings are stabilized in P1 AgN7 and P21/c AgN5.At 26.3 GPa,P-1 AgN4 is synthesized,featuring infinite onedimensional nitrogen chains composed of alternating N2 and N6 rings,a unique catenation not observed in other polynitrides.In addition,AgN7,AgN5,and AgN4 possess significantly higher volumetric energy densities Ev than the conventional explosive TNT,making them promising high-energy-density materials.展开更多
The syntheses of a number of C-aryl-N-3-butenyl nitrones [aryl ring=4-CH_3O-phenyl (1a), phenyl(1b), 4-Cl-phenyl(1e), 4-Br-phenyl(1d), 4-NO2-phenyl(1e), 2-furyl (1f), 2-thienyl (1g), 2-pyrryl(1h)] and their thermochem...The syntheses of a number of C-aryl-N-3-butenyl nitrones [aryl ring=4-CH_3O-phenyl (1a), phenyl(1b), 4-Cl-phenyl(1e), 4-Br-phenyl(1d), 4-NO2-phenyl(1e), 2-furyl (1f), 2-thienyl (1g), 2-pyrryl(1h)] and their thermochemical reactions have been investigated. The thermocycloadditions of 1a-1h are regiospecific in forming a novel heterobicyclic ring system. Exo-aryl-1-aza-7-oxabicyclo- [2.2.1]heptane.展开更多
Planet gear systems(PGSs)are key components of transmission mechanisms.Structural and material characteristics of gearbox and shaft can affect the support stiffness and vibrations of PGSs.The ring gear flexibility sho...Planet gear systems(PGSs)are key components of transmission mechanisms.Structural and material characteristics of gearbox and shaft can affect the support stiffness and vibrations of PGSs.The ring gear flexibility should affect the vibrations of PGSs too.However,most previous work did not completely consider the effects of the ring gear flexibility on the vibrations of PGSs and flexible supports of ring and sun gears.Thus,this paper presents a flexible-rigid coupling multi-body dynamic(FMBD)model for a PGS with the flexible supports and ring gear flexibility.A finite element model of ring gear is established to formulate the ring gear flexibility.The influences of clearance and damping of planet bearings on the vibrations of PGS are considered.The effects of flexible supports and ring gear flexibility on the vibrations of PGS under different moment and speed conditions are studied.The statistical parameters and peak frequencies of PGS from the proposed FMBD and previous rigid multi-body dynamic(RMBD)models are compared.The results denote that the flexible support has a great effect on the vibrations of PGS.This paper can provide some guidance for the support structure design and vibration control for PGSs.展开更多
As the popularization of dual ring fieldbus, the optimized dual ring synchronization methods are still in short. The current synchronization methods are generally established in traditional industrial fieldbus, in whi...As the popularization of dual ring fieldbus, the optimized dual ring synchronization methods are still in short. The current synchronization methods are generally established in traditional industrial fieldbus, in which transmission is commonly considered in single track, the two-way transmitting cannot take full effect, and would result in unwanted idle load on equipment lines. In stamp-transferring part, the synchronizing algorithm is not properly processed to diminish the latency, so the real-time performance of entire system cannot be ensured. To support the synchronization control of stations in the CNC system, a real-time time synchronization method for dual ring fieldbus in the CNC system is designed in this paper. In this method a synchronizing message transmission scheme based on dual ring architecture and the synchronization algorithm between master and secondary stations are integrated. In the scheme, the clock models of both master and secondary stations are optimized with corresponding modules and the stamp data transmission based on the dual ring fieldbus is devised exclusively, so the transmitting efficiency improves with less idle work. In the algorithm, all the secondary stations can accomplish the consistent state with master station by updating clock discrepancy information in one communication cycle, and it takes the advantage of two-way transmitting and makes the best use of dual ring structure, so the real-time performance of the system can be promoted while retaining the precision of synchronization. To evaluate the performance, the costs of the method and errors during synchronizing are noted and analyzed based on the actual running environment in the industrial fieldbus. The results show that it reduces communication cost and ensures the smoothness of the system with low lag effects under heavy load. The proposed time synchronization method optimizes the architecture of sync message transmission in dual ring fieldbus, and improves the efficiency of time synchronization in the stations of CNC system.展开更多
BACKGROUND The use of endoscopic submucosal dissection(ESD)for treating early signet ring cell carcinoma(SRC)is controversial due to the risk of lymph node metastasis.AIM To carry out a meta-analysis to evaluate ESD f...BACKGROUND The use of endoscopic submucosal dissection(ESD)for treating early signet ring cell carcinoma(SRC)is controversial due to the risk of lymph node metastasis.AIM To carry out a meta-analysis to evaluate ESD for therapeutic efficacy and safety in early signet ring cell gastric cancer.METHODS The PubMed,Web of Science,Cochrane Library,and EMBASE databases were used to search for relevant studies evaluating the therapeutic efficacy and safety of ESD in SRC.The rates of recurrence,complete resection,incomplete resection,curative resection,en bloc resection,and adverse events were extracted and analyzed.The methodological quality of the enrolled studies was assessed using the Newcastle-Ottawa Scale.Publication bias was evaluated by the Egger’s test.Institutional review board approval and written consent were not needed for this report.RESULTS This meta-analysis enrolled seven studies with 653 participants undergoing ESD treatment for early SRC.The overall recurrence rate was 0.010[95%confidence interval(CI):0.000-0.040,Z=1.422,P=0.155].The total lymph-ovascular invasion rate was 0.038(95%CI:0.007-0.088,Z=3.026,P=0.002).The total en bloc resection rate was estimated at 0.984(95%CI:0.925-1.000,Z=19.463,P=0.000).The total complete and incomplete resection rates were estimated at 0.785(95%CI:0.596-0.928,Z=9.789,P=0.000)and 0.188(95%CI:0.016-0.468,Z=2.531,P=0.011),respectively.The total procedureassociated gastric hemorrhage and perforation rates were estimated at 0.026(95%CI:0.005-0.061,Z=3.006 P=0.003)and 0.004(95%CI:0.000-0.028,Z=0.938,P=0.348),respectively.The curative resection,vertical margin invasion,and lateral margin invasion rates were 72.1%(145/341),2.3%(8/348),and 34.45%(41/119),respectively.CONCLUSION ESD constitutes a promising therapeutic approach for early undifferentiated SRC gastric cancer.However,further improvements are required for increasing its treatment efficacy and reducing adverse outcomes.展开更多
The adaptive coupled synchronization method for non-autonomous systems is proposed. This method can avoid estimating the value of coupling coefficient. Under the uniform Lipschitz assumption, we derive the asymptotica...The adaptive coupled synchronization method for non-autonomous systems is proposed. This method can avoid estimating the value of coupling coefficient. Under the uniform Lipschitz assumption, we derive the asymptotical synchronization for a general coupling ring network with N identical non-autonomous systems~ even when N is large enough. Strict theoretical proofs are given. Numerical simulations illustrate the effectiveness of the present method.展开更多
The development of a detuning system for the precision control of electron energy is a major challenge when electron targets are used in ion-storage rings.Thus,a high-precision,high-voltage,detuning system was develop...The development of a detuning system for the precision control of electron energy is a major challenge when electron targets are used in ion-storage rings.Thus,a high-precision,high-voltage,detuning system was developed for the electron target of a high-intensity heavy-ion accelerator facility-spectrometer ring(HIAF-SRing)to produce accurate electron-ion relative energies during experiments.The system consists of auxiliary,and high-voltage detuning power supplies.The front stage of the auxiliary power supply adopts an LCC resonant converter operating in the soft-switching state and an LC filter for a sinusoidal waveform output in the post-stage.The detuning power supply is a high-voltage pulse amplifier(HVPA)connected with a high-voltage DC(HVDC)module in series.In this paper,the design and development of the detuning system are described in detail,and the test bench is presented.The test results demonstrated that the detuning system conforms to the technical specifications of the dielectronic recombination(DR)experiment.Finally,a Fe15+DR spectrum was measured using the detuning system.The experimental data demonstrated a good experimental resolution and verified the reliability and feasibility of the design.展开更多
The important status of guide ring in large power plants and its manufacturing methods were introduced. The advantages of manufacturing methods including welding and electrolysis were discussed.In order to ensure the ...The important status of guide ring in large power plants and its manufacturing methods were introduced. The advantages of manufacturing methods including welding and electrolysis were discussed.In order to ensure the brazing quality of the guide ring,ultrasonic nondestructive testing(UNDT) method was used in this study.According to the features of the defects that may show up during brazing,the feasibility and reliability of UNDT were proved in theory.Based on the theory,an ultrasonic C-scan imaging test method was developed using a water immersion focusing probe.According to the features of the inspected images,the defects were segmented using a morphology image processing based method.The defects can be localized and sized by employing the algorithm of area reconstruction.At last,the combination ratio of brazing interface can be calculated and the brazing quality of the guide ring can be evaluated.展开更多
(±)-Cyclopeltains A and B(1 and 2),two pairs of unusual alkylated adenine derivatives,were isolated from the insect Cyclopelta parva and structurally characterized.1 and 2 both possess a 6/5/7/5 ring system arisi...(±)-Cyclopeltains A and B(1 and 2),two pairs of unusual alkylated adenine derivatives,were isolated from the insect Cyclopelta parva and structurally characterized.1 and 2 both possess a 6/5/7/5 ring system arising from the alkylation of N^(7) and N^(10) by a C6 unit and the formation of a furan ring.A plausible biosynthetic pathway for 1 and 2 was proposed.Biological evaluation of the enantiomers of 1 and 2 revealed that(−)-1 and(+)-2 could inhibit the production of TNF-αand IL-6 and the expression of iNOS,COX-2,and p-NF-κB.展开更多
For the first time,metal hydrogen sulfates and phosphates/silica gel have been studied as efficient and powerful solid acid catalysts in the ring opening of epoxides with thiocyanate anion.The most significant result ...For the first time,metal hydrogen sulfates and phosphates/silica gel have been studied as efficient and powerful solid acid catalysts in the ring opening of epoxides with thiocyanate anion.The most significant result was obtained by Al(HSO4)3/SiO2which afforded the corresponding β-hydroxy thiocyanates under mild reaction conditions and in very short reaction times.The cheapness, availability of the catalyst,ease of procedure and work-up make this method attractive for the organic synthesis.展开更多
BACKGROUND The clinical significance of signet ring cells(SRCs)in surgical esophageal and esophagogastric junction adenocarcinoma(EEGJA)remains unclear now.AIM To explore the association between the presence of SRCs a...BACKGROUND The clinical significance of signet ring cells(SRCs)in surgical esophageal and esophagogastric junction adenocarcinoma(EEGJA)remains unclear now.AIM To explore the association between the presence of SRCs and the clinicopathological and prognostic characteristics in surgical EEGJA patients by combining and analyzing relevant studies.METHODS The PubMed,Web of Science,and EMBASE electronic databases were searched for the relevant literature up to March 28,2021.The relative risk(RR)with 95%confidence interval(CI)was calculated to assess the relationship between SRCs and clinicopathological parameters of surgical EEGJA patients,and the hazard ratio(HR)with 95%CI was calculated to explore the impact of SRC on the prognosis.All statistical analyses were conducted with STATA 12.0 software.RESULTS A total of ten articles were included,involving 30322 EEGJA patients.The pooled results indicated that the presence of SRCs was significantly associated with tumor location(RR:0.76,95%CI:0.61-0.96,P=0.022;I2=49.4%,P=0.160)and tumor-node-metastasis stage(RR:1.30,95%CI:1.02-1.65,P=0.031;I2=73.1%,P=0.002).Meanwhile,the presence of SRCs in surgical EEGJA patients predicted a poor overall survival(HR:1.36,95%CI:1.12-1.65,P=0.002;I2=85.7%,P<0.001)and disease-specific survival(HR:1.86,95%CI:1.55-2.25,P<0.001;I2=63.1%,P=0.043).CONCLUSION The presence of SRCs is related with advanced tumor stage and poor prognosis and could serve as a reliable and effective parameter for the prediction of postoperative survival and formulation of therapy strategy in EEGJA patients.However,more high-quality studies are still needed to verify the above findings.展开更多
In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the center station （CS） to suppress the optical carrier for the modulation depth enhancement. Simultaneous...In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the center station （CS） to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave induced by the Brillouin amplification injects and locks the Fabry-Perot （FP） laser to output a signal-mode optical source, which works as the uplink optical carrier.展开更多
Ligand effect of the catalytic system WCl6-Et2AlCl for ring opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) was investigated. The experimental results show that adding sterically hindered phenol-2...Ligand effect of the catalytic system WCl6-Et2AlCl for ring opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) was investigated. The experimental results show that adding sterically hindered phenol-2. 6-di-tert-butylcresylol(DTBC) in the catalytic system not only can obviously increase the monomer conversion of polymerization but also improve the mechanical properties, such as notched impact strength (NIS), tensile strength (TS) ect. 5 of the synthesized polyicycolpentadiene (PDCPD). A similar effect can be observed by using a sterically hindered polymeric phenol - linear phenol formaldehyde resin (LPF) as a ligand.展开更多
A compact and broadband circularly polarized （CP） annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems （GNSS） in the L1 band. The annular ring is excited by two mo...A compact and broadband circularly polarized （CP） annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems （GNSS） in the L1 band. The annular ring is excited by two modified L-probes with quadrature phase difference. It has a 36.3% 10-dB return loss bandwidth and a 13% 3-dB axial ratio bandwidth, because of the orthogonal L-probes with 90° phase difference. The measured peak gain of the antenna is 3.9 dBic. It can detect the satellites at lower elevation as its half power beam-width （HPBW） is 113° in both the x-z and y-z planes, achieving a cross-polarization level of larger than 25 dB. Noticeably, the antenna achieves 89% size reduction compared with the conventional half wavelength patch antennas. It can be used in hand-held navigation devices of multiple GNSS such as COMPASS, Galileo, GPS and GLONASS.展开更多
A proposed strategy for constructing the nine-membered azonane ring system embedded in the isotwistane framework of palhinine A has been preliminarily studied on the basis of an azidoketol fragmentation reaction toget...A proposed strategy for constructing the nine-membered azonane ring system embedded in the isotwistane framework of palhinine A has been preliminarily studied on the basis of an azidoketol fragmentation reaction together with a SmI2-mediated pinacol coupling. Albeit negative results for building the azonane ring scaffold via a tertiary azidoketol fragmentation, the present exploration strategically provided an endeavor to probe the synthetically challenging issue in the synthetic study of palhinine A.展开更多
文摘The magnetic behavior of a two-electron quantum dot/ring system is analytically studied with electron-electron(e-e)interaction taking into account the Rashba spin-orbit interaction(SOI)and magnetic field.The Jacobi transformation has been employed to separate the Hamiltonian of the system to the center of mass and relative terms.The Schrödinger equation is analytically solved,and energy spectra are obtained.Then,the magnetization and susceptibility are calculated.The magnetization decreases by raising the magnetic field without and with SOI,and also without e-e interaction.Also,the SOI slightly modifies the magnetization of the system without e-e interaction.The susceptibility displays a peak structure as the magnetic field changes from low values to high values.The susceptibility by considering e-e interaction and without the SOI is always negative and its value decreases by rising the magnetic field.The susceptibility displays a transition from diamagnetic to paramagnetic with e-e interaction and SOI.
基金financially supported by the National Natural Science Foundation of China(Nos.21901020 and 22003076)China Postdoctoral Science Foundation(No.2021M701818)+1 种基金Shandong Provincial Natural Science Foundation(No.ZR2022QE237)the Qingdao Postdoctoral Applied Research Project.H.Liu sincerely acknowledges financial support from the Taishan Scholars Program(No.tsqn202211165)。
文摘High catalytic efficiencies in ring opening polymerization(ROP)of a large ring-sized macrolactone,ω-pentadecalactone(PDL),by using transition metal Fe(II)-based catalysts were achieved for the first time in this study.Benefited from the bulky nature of the ligatedα-diimine ligands,as evidenced from single-crystal structures,as well as the weakly oxophilic nature of the metal centers,chain transesterification reactions could be partially suppressed,allowing the polymerization proceed in a living-like and semi-controllable manner,i.e.good linear dependence of propagation rates on catalyst concentration and PDL concentration as observed in the detailed kinetics studies.The whole polymerization proceeds via a“coordination-insertion”mechanism,and with the aid of density functional theory(DFT)calculation studies,a“slow insertion→fast elimination”manner was demonstrated for the monomer propagation step,suggesting the insertion of Fe-OR into the carbonyl group C=O as the rate-determining step.The present catalytic system also showed fast chain transfer reactions to alcohol compounds,affording quasi-immortal characteristics.DFT calculations showed that such a transfer reaction only required an energy barrier of 6.4 kcal/mol,performing a good consistency with the fast chain transfer rates.
基金supported by the Jiangsu Provincial Key Research and Development Program(BE2022072)the National Natural Science Foundation of China(12141304)the Natural Science Foundation of Jiangsu Province(BK20231134).
文摘To address the installation challenges of a 2-m ring Gregorian telescope system,and similar optical systems with a small width-to-radius ratio,we propose a detection method combining local interferometry with a comparison model.This method enhances the precision of system calibration by establishing a dataset that delineates the relationship between secondary mirror misalignment and wavefront aberration,subsequently inferring the misalignment from interferometric detection results during the calibration process.For the 2-m ring telescope,we develop a detection model using five local sub-apertures,enabling a root-mean-square detection accuracy of 0:0225λ(λ=632:8 nm)for full-aperture wavefront aberration.The calibration results for the 2-m Ring Solar Telescope system indicate that the root-mean-square value of sub-aperture wavefront aberration reaches 0.104λ,and the root-mean-square value of spliced full-aperture measurement yields reaches 0.112λ.This method offers a novel approach for calibrating small width-toradius ratio telescope systems and can be applied to the calibration of other irregular-aperture optical systems.
基金supported by the National Key R&D Program of China(Grant No.2023YFA1406200)the National Natural Science Foundation of China(NSFC)(Grant Nos.12174143 and 12404014)the Basic Science Center Project of the NSFC(Grant No.52388201).
文摘High pressure enables the creation of novel functional materials by modifying chemical bonding and crystal structure,opening avenues for the development of high-energy-density polynitrogen materials.We present the high-pressure synthesis of three polynitrides P1 AgN7,P21/c AgN5,and P-1 AgN4,achieved through direct reactions between silver and nitrogen.Notably,the synthesis pressures required for the formation of N5 and N6 rings from metal–nitrogen reactions in this work represent the lowest values reported to date in high-pressure studies.At 15 GPa,isolated N5 rings are stabilized in P1 AgN7 and P21/c AgN5.At 26.3 GPa,P-1 AgN4 is synthesized,featuring infinite onedimensional nitrogen chains composed of alternating N2 and N6 rings,a unique catenation not observed in other polynitrides.In addition,AgN7,AgN5,and AgN4 possess significantly higher volumetric energy densities Ev than the conventional explosive TNT,making them promising high-energy-density materials.
文摘The syntheses of a number of C-aryl-N-3-butenyl nitrones [aryl ring=4-CH_3O-phenyl (1a), phenyl(1b), 4-Cl-phenyl(1e), 4-Br-phenyl(1d), 4-NO2-phenyl(1e), 2-furyl (1f), 2-thienyl (1g), 2-pyrryl(1h)] and their thermochemical reactions have been investigated. The thermocycloadditions of 1a-1h are regiospecific in forming a novel heterobicyclic ring system. Exo-aryl-1-aza-7-oxabicyclo- [2.2.1]heptane.
基金Projects(51605051,51975068)supported by the National Natural Science Foundation of China。
文摘Planet gear systems(PGSs)are key components of transmission mechanisms.Structural and material characteristics of gearbox and shaft can affect the support stiffness and vibrations of PGSs.The ring gear flexibility should affect the vibrations of PGSs too.However,most previous work did not completely consider the effects of the ring gear flexibility on the vibrations of PGSs and flexible supports of ring and sun gears.Thus,this paper presents a flexible-rigid coupling multi-body dynamic(FMBD)model for a PGS with the flexible supports and ring gear flexibility.A finite element model of ring gear is established to formulate the ring gear flexibility.The influences of clearance and damping of planet bearings on the vibrations of PGS are considered.The effects of flexible supports and ring gear flexibility on the vibrations of PGS under different moment and speed conditions are studied.The statistical parameters and peak frequencies of PGS from the proposed FMBD and previous rigid multi-body dynamic(RMBD)models are compared.The results denote that the flexible support has a great effect on the vibrations of PGS.This paper can provide some guidance for the support structure design and vibration control for PGSs.
基金supported by National Projects for Science and Technology Development of China(Grant No.2011ZX04016-071)National Basic Research Program of China(973 Program,Grant No.2011CB302400-G,the mathematical mechanization method and its application in digital design and manufacturing)
文摘As the popularization of dual ring fieldbus, the optimized dual ring synchronization methods are still in short. The current synchronization methods are generally established in traditional industrial fieldbus, in which transmission is commonly considered in single track, the two-way transmitting cannot take full effect, and would result in unwanted idle load on equipment lines. In stamp-transferring part, the synchronizing algorithm is not properly processed to diminish the latency, so the real-time performance of entire system cannot be ensured. To support the synchronization control of stations in the CNC system, a real-time time synchronization method for dual ring fieldbus in the CNC system is designed in this paper. In this method a synchronizing message transmission scheme based on dual ring architecture and the synchronization algorithm between master and secondary stations are integrated. In the scheme, the clock models of both master and secondary stations are optimized with corresponding modules and the stamp data transmission based on the dual ring fieldbus is devised exclusively, so the transmitting efficiency improves with less idle work. In the algorithm, all the secondary stations can accomplish the consistent state with master station by updating clock discrepancy information in one communication cycle, and it takes the advantage of two-way transmitting and makes the best use of dual ring structure, so the real-time performance of the system can be promoted while retaining the precision of synchronization. To evaluate the performance, the costs of the method and errors during synchronizing are noted and analyzed based on the actual running environment in the industrial fieldbus. The results show that it reduces communication cost and ensures the smoothness of the system with low lag effects under heavy load. The proposed time synchronization method optimizes the architecture of sync message transmission in dual ring fieldbus, and improves the efficiency of time synchronization in the stations of CNC system.
基金Supported by National Natural Science Foundation of China,No.8177030774.
文摘BACKGROUND The use of endoscopic submucosal dissection(ESD)for treating early signet ring cell carcinoma(SRC)is controversial due to the risk of lymph node metastasis.AIM To carry out a meta-analysis to evaluate ESD for therapeutic efficacy and safety in early signet ring cell gastric cancer.METHODS The PubMed,Web of Science,Cochrane Library,and EMBASE databases were used to search for relevant studies evaluating the therapeutic efficacy and safety of ESD in SRC.The rates of recurrence,complete resection,incomplete resection,curative resection,en bloc resection,and adverse events were extracted and analyzed.The methodological quality of the enrolled studies was assessed using the Newcastle-Ottawa Scale.Publication bias was evaluated by the Egger’s test.Institutional review board approval and written consent were not needed for this report.RESULTS This meta-analysis enrolled seven studies with 653 participants undergoing ESD treatment for early SRC.The overall recurrence rate was 0.010[95%confidence interval(CI):0.000-0.040,Z=1.422,P=0.155].The total lymph-ovascular invasion rate was 0.038(95%CI:0.007-0.088,Z=3.026,P=0.002).The total en bloc resection rate was estimated at 0.984(95%CI:0.925-1.000,Z=19.463,P=0.000).The total complete and incomplete resection rates were estimated at 0.785(95%CI:0.596-0.928,Z=9.789,P=0.000)and 0.188(95%CI:0.016-0.468,Z=2.531,P=0.011),respectively.The total procedureassociated gastric hemorrhage and perforation rates were estimated at 0.026(95%CI:0.005-0.061,Z=3.006 P=0.003)and 0.004(95%CI:0.000-0.028,Z=0.938,P=0.348),respectively.The curative resection,vertical margin invasion,and lateral margin invasion rates were 72.1%(145/341),2.3%(8/348),and 34.45%(41/119),respectively.CONCLUSION ESD constitutes a promising therapeutic approach for early undifferentiated SRC gastric cancer.However,further improvements are required for increasing its treatment efficacy and reducing adverse outcomes.
基金Project supported by the National Natural Science Foundation of China(Grant No10372054)the Science Foundation of Jiangnan University,China(Grant No000408)
文摘The adaptive coupled synchronization method for non-autonomous systems is proposed. This method can avoid estimating the value of coupling coefficient. Under the uniform Lipschitz assumption, we derive the asymptotical synchronization for a general coupling ring network with N identical non-autonomous systems~ even when N is large enough. Strict theoretical proofs are given. Numerical simulations illustrate the effectiveness of the present method.
文摘The development of a detuning system for the precision control of electron energy is a major challenge when electron targets are used in ion-storage rings.Thus,a high-precision,high-voltage,detuning system was developed for the electron target of a high-intensity heavy-ion accelerator facility-spectrometer ring(HIAF-SRing)to produce accurate electron-ion relative energies during experiments.The system consists of auxiliary,and high-voltage detuning power supplies.The front stage of the auxiliary power supply adopts an LCC resonant converter operating in the soft-switching state and an LC filter for a sinusoidal waveform output in the post-stage.The detuning power supply is a high-voltage pulse amplifier(HVPA)connected with a high-voltage DC(HVDC)module in series.In this paper,the design and development of the detuning system are described in detail,and the test bench is presented.The test results demonstrated that the detuning system conforms to the technical specifications of the dielectronic recombination(DR)experiment.Finally,a Fe15+DR spectrum was measured using the detuning system.The experimental data demonstrated a good experimental resolution and verified the reliability and feasibility of the design.
基金the Fund of the State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology(No.welding 10-013)
文摘The important status of guide ring in large power plants and its manufacturing methods were introduced. The advantages of manufacturing methods including welding and electrolysis were discussed.In order to ensure the brazing quality of the guide ring,ultrasonic nondestructive testing(UNDT) method was used in this study.According to the features of the defects that may show up during brazing,the feasibility and reliability of UNDT were proved in theory.Based on the theory,an ultrasonic C-scan imaging test method was developed using a water immersion focusing probe.According to the features of the inspected images,the defects were segmented using a morphology image processing based method.The defects can be localized and sized by employing the algorithm of area reconstruction.At last,the combination ratio of brazing interface can be calculated and the brazing quality of the guide ring can be evaluated.
基金supported by the National Key Research and Development Program of China(2017YFA0503900)Shenzhen Government’s Plan of Science and Technology(JCYJ20170412110504956)+2 种基金the Shenzhen Fundamental Research Program(JCYJ20200109114225087)the National Science Fund for Distinguished Young Scholars(81525026)the Guangdong Key Laboratory for Functional Substances in Medicinal Edible Resources and Healthcare Products(2021B1212040015).
文摘(±)-Cyclopeltains A and B(1 and 2),two pairs of unusual alkylated adenine derivatives,were isolated from the insect Cyclopelta parva and structurally characterized.1 and 2 both possess a 6/5/7/5 ring system arising from the alkylation of N^(7) and N^(10) by a C6 unit and the formation of a furan ring.A plausible biosynthetic pathway for 1 and 2 was proposed.Biological evaluation of the enantiomers of 1 and 2 revealed that(−)-1 and(+)-2 could inhibit the production of TNF-αand IL-6 and the expression of iNOS,COX-2,and p-NF-κB.
基金the Shahid Chamran University Research Council for partial financial support of this work
文摘For the first time,metal hydrogen sulfates and phosphates/silica gel have been studied as efficient and powerful solid acid catalysts in the ring opening of epoxides with thiocyanate anion.The most significant result was obtained by Al(HSO4)3/SiO2which afforded the corresponding β-hydroxy thiocyanates under mild reaction conditions and in very short reaction times.The cheapness, availability of the catalyst,ease of procedure and work-up make this method attractive for the organic synthesis.
文摘BACKGROUND The clinical significance of signet ring cells(SRCs)in surgical esophageal and esophagogastric junction adenocarcinoma(EEGJA)remains unclear now.AIM To explore the association between the presence of SRCs and the clinicopathological and prognostic characteristics in surgical EEGJA patients by combining and analyzing relevant studies.METHODS The PubMed,Web of Science,and EMBASE electronic databases were searched for the relevant literature up to March 28,2021.The relative risk(RR)with 95%confidence interval(CI)was calculated to assess the relationship between SRCs and clinicopathological parameters of surgical EEGJA patients,and the hazard ratio(HR)with 95%CI was calculated to explore the impact of SRC on the prognosis.All statistical analyses were conducted with STATA 12.0 software.RESULTS A total of ten articles were included,involving 30322 EEGJA patients.The pooled results indicated that the presence of SRCs was significantly associated with tumor location(RR:0.76,95%CI:0.61-0.96,P=0.022;I2=49.4%,P=0.160)and tumor-node-metastasis stage(RR:1.30,95%CI:1.02-1.65,P=0.031;I2=73.1%,P=0.002).Meanwhile,the presence of SRCs in surgical EEGJA patients predicted a poor overall survival(HR:1.36,95%CI:1.12-1.65,P=0.002;I2=85.7%,P<0.001)and disease-specific survival(HR:1.86,95%CI:1.55-2.25,P<0.001;I2=63.1%,P=0.043).CONCLUSION The presence of SRCs is related with advanced tumor stage and poor prognosis and could serve as a reliable and effective parameter for the prediction of postoperative survival and formulation of therapy strategy in EEGJA patients.However,more high-quality studies are still needed to verify the above findings.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.60377024, 60877053)the Science Foundation of Science and Technology Commission of Shanghai Municipality (Grant No.08DZ1500115)
文摘In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the center station （CS） to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave induced by the Brillouin amplification injects and locks the Fabry-Perot （FP） laser to output a signal-mode optical source, which works as the uplink optical carrier.
文摘Ligand effect of the catalytic system WCl6-Et2AlCl for ring opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) was investigated. The experimental results show that adding sterically hindered phenol-2. 6-di-tert-butylcresylol(DTBC) in the catalytic system not only can obviously increase the monomer conversion of polymerization but also improve the mechanical properties, such as notched impact strength (NIS), tensile strength (TS) ect. 5 of the synthesized polyicycolpentadiene (PDCPD). A similar effect can be observed by using a sterically hindered polymeric phenol - linear phenol formaldehyde resin (LPF) as a ligand.
基金supported by the NSFC-Guangdong (Grant No.U1035002) and NSFC-NSAF (Grant No.10976010)National Key Project of Science and Technology of China (Grant No. 2009ZX03006-003)the Technology Key Projects of Guangdong Province of China (Grant Nos.2009A080207006 and 2009A080207002)
文摘A compact and broadband circularly polarized （CP） annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems （GNSS） in the L1 band. The annular ring is excited by two modified L-probes with quadrature phase difference. It has a 36.3% 10-dB return loss bandwidth and a 13% 3-dB axial ratio bandwidth, because of the orthogonal L-probes with 90° phase difference. The measured peak gain of the antenna is 3.9 dBic. It can detect the satellites at lower elevation as its half power beam-width （HPBW） is 113° in both the x-z and y-z planes, achieving a cross-polarization level of larger than 25 dB. Noticeably, the antenna achieves 89% size reduction compared with the conventional half wavelength patch antennas. It can be used in hand-held navigation devices of multiple GNSS such as COMPASS, Galileo, GPS and GLONASS.
基金supported by the National Natural Science Foundation of China (21572083, 21322201, 21290180)the Fundamental Research Funds for the Central Universities (lzujbky-2015-48, lzujbky2016-ct07)+1 种基金Program for Changjiang Scholars and Innovative Research Team in University (IRT_15R28)the 111 Project of MOE of China (111-2-17)
文摘A proposed strategy for constructing the nine-membered azonane ring system embedded in the isotwistane framework of palhinine A has been preliminarily studied on the basis of an azidoketol fragmentation reaction together with a SmI2-mediated pinacol coupling. Albeit negative results for building the azonane ring scaffold via a tertiary azidoketol fragmentation, the present exploration strategically provided an endeavor to probe the synthetically challenging issue in the synthetic study of palhinine A.
