Nondestructive and noninvasive neutron assays are essential applications of neutron techniques.Neutron resonance transmission analysis(NRTA)is a powerful nondestructive method for investigating the elemental compositi...Nondestructive and noninvasive neutron assays are essential applications of neutron techniques.Neutron resonance transmission analysis(NRTA)is a powerful nondestructive method for investigating the elemental composition of an object.The back-streaming neutron line(Back-n)is a newly built time-of-flight facility at the China Spallation Neutron Source(CSNS)that provides neutrons in the eV to 300 MeV range.A feasibility study of the NRTA method for nuclide identification was conducted at the CSNS Back-n via two test experiments.The results demonstrate that it is feasible to identify different elements and isotopes in samples using the NRTA method at Back-n.This study reveals its potential future applications.展开更多
A new measurement method for the spatial distribution of neutron beam flux in boron neutron capture therapy(BNCT)is being developed based on the two-dimensional Micromegas detector.To address the issue of long process...A new measurement method for the spatial distribution of neutron beam flux in boron neutron capture therapy(BNCT)is being developed based on the two-dimensional Micromegas detector.To address the issue of long processing times in traditional offline position reconstruction methods,this paper proposes a field programmable gate array based online position reconstruction method utilizing the micro-time projection chamber principle.This method encapsulates key technical aspects:a self-adaptive serial link technique built upon the dynamical adjustment of the delay chain length,fast sorting,a coordinate-matching technique based on the mapping between signal timestamps and random access memory(RAM)addresses,and a precise start point-merging technique utilizing a circular combined RAM.The performance test of the selfadaptive serial link shows that the bit error rate of the link is better than 10-12 at a confidence level of 99%,ensuring reliable data transmission.The experiment utilizing the readout electronics and Micromegas detector shows a spatial resolution of approximately 1.4 mm,surpassing the current method’s resolution level of 5 mm.The beam experiment confirms that the readout electronics system can obtain the flux spatial distribution of neutron beams online,thus validating the feasibility of the position reconstruction method.The online position reconstruction method avoids traditional methods,such as bubble sorting and traversal searching,simplifies the design of the logic firmware,and reduces the time complexity from O(n2)to O(n).This study contributes to the advancement in measuring neutron beam flux for BNCT.展开更多
Objectives: To investigate the effect of lumbar interbody fusion via the oblique lateral approach (OLIF) in the treatment of single level lumbar spondylolisthesis. Methods: Retrospective analysis was made on 32 cases ...Objectives: To investigate the effect of lumbar interbody fusion via the oblique lateral approach (OLIF) in the treatment of single level lumbar spondylolisthesis. Methods: Retrospective analysis was made on 32 cases of single level lumbar spondylolisthesis treated by lumbar interbody fusion via the oblique lateral approach from July 2020 to July 2021. 14 males and 18 females;the age was (66.5 ± 11.5) years (55 - 82 years). 1) The operation time, intraoperative blood loss and complications were recorded;2) the scores of visual analog scale. VAS and Oswestry disability index (ODI) of low back pain and lower limb pain were collected before operation and at the last follow-up;by observing the imaging data, the height of the intervertebral space, the anterior convex angle of the intervertebral space, the anterior convex angle of the lumbar spine, the sagittal diameter of the dural sac and the spondylolisthesis were measured. Results: All patients successfully completed the operation, the average operation time was (103.9 ± 21.1) min, the average intraoperative bleeding volume was (72.3 ± 16.4) ml. There was no vascular injury during the operation, no infection occurred in all surgical incisions, and Class I/A healing was achieved. The VAS scores of low back pain and leg pain before operation and at the last follow-up were lower than those before operation, and the difference was statistically significant (P < 0.05);the ODI at the last follow-up was lower than that before operation, and the difference was statistically significant (P < 0.05). At the last follow-up, the height of intervertebral space, the height of intervertebral foramen and the sagittal diameter of dural sac were greater than those before operation, with statistically significant differences (P < 0.05);the spondylolisthesis rate at the last follow-up was lower than that before operation, with a statistically significant difference (P < 0.05). Left thigh surface numbness occurred in 2 cases (6.3%) and disappeared after 1 week;Hip flexion weakness occurred in 1 case (0.03%), which recovered after 12 days;there were no complications such as retroperitoneal hematoma, ureteral injury, retrograde ejaculation, intestinal and lumbar plexus injury. Conclusion: The early clinical effect of OLIF in the treatment of single level lumbar spondylolisthesis is significant. This surgical method is minimally invasive, safe and effective, which can significantly reduce the amount of intraoperative bleeding and reduce the risk of postoperative complications. Its main working principle is to make the annulus fibrosus, posterior longitudinal ligament and ligamentum flavum shrink and recover the height of the intervertebral space through decompression, loosening and stretching of the intervertebral space, so as to achieve the reduction of the slipped vertebral body, increase the height of the intervertebral foramen Enlarge the spinal canal volume and eliminate dynamic compression to play an indirect decompression role, improve the symptoms of low back and leg pain, and reconstruct the stability of the spine through interbody fusion.展开更多
The ^(232)Th(n,f)cross section is very important in basic nuclear physics and applications based on the Th/U fuel cycle.Using the time-of-flight method and a multi-cell fast-fission ionization chamber,a novel measurem...The ^(232)Th(n,f)cross section is very important in basic nuclear physics and applications based on the Th/U fuel cycle.Using the time-of-flight method and a multi-cell fast-fission ionization chamber,a novel measurement of the^(232)Th(n,f)cross sec-tion relative to^(235)U in the 1–200 MeV range was performed at the China Spallation Neutron Source Back-n white neutron source(Back-n).The fission event-neutron energy spectra of^(232)Th and^(235)U fission cells were measured in the single-bunch mode.Corrected 232Th/235U fission cross-sectional ratios were obtained,and the measurement uncertainties were 2.5–3.7%for energies in the 2–20 MeV range and 3.6–6.2%for energies in the 20–200 MeV range.The^(232)Th(n,f)cross section was obtained by introducing the standard cross section of^(235)U(n,f).The results were compared with those of previous theoreti-cal calculations,measurements,and evaluations.The measured 232Th fission cross section agreed with the main evaluation results in terms of the experimental uncertainty,and 232Th fission resonances were observed in the 1–3 MeV range.The present results provide^(232)Th(n,f)cross-sectional data for the evaluation and design of Th/U cycle nuclear systems.展开更多
In the process of engineering construction such as tunnels and slopes,rock mass is frequently subjected to multiple levels of loading and unloading,while previous research ignores the impact of unloading rate on the s...In the process of engineering construction such as tunnels and slopes,rock mass is frequently subjected to multiple levels of loading and unloading,while previous research ignores the impact of unloading rate on the stability of rock mass.A number of uniaxial multi-level cyclic loading-unloading experiments were conducted to better understand the effect of unloading rate on the deformation behavior,energy evolution,and damage properties of rock-like material.The experimental results demonstrated that the unloading rate and relative cyclic number clearly influence the deformation behavior and energy evo-lution of rock-like samples.In particular,as the relative cyclic number rises,the total strain and reversible strain both increase linearly,while the total energy density,elastic energy density,and dissipated energy density all rise nonlinearly.In contrast,the irreversible strain first decreases quickly,then stabilizes,and finally rises slowly.As the unloading rate increases,the total strain and reversible strain both increase,while the irreversible strain decreases.The dissipated energy damage was examined in light of the aforementioned experimental findings.The accuracy of the proposed damage model,which takes into account the impact of the unloading rate and relative cyclic number,is then confirmed by examining the consistency between the model predicted and the experimental results.The proposed damage model will make it easier to foresee how the multi-level loading-unloading cycles will affect the rock-like materials.展开更多
AIM: To identify and understand the regular distribution pattern and primary penetration site for Salmonella enteritidis (S. enteritidis) in the gastrointestinal tract. METHODS: Based on the species-specific DNA seque...AIM: To identify and understand the regular distribution pattern and primary penetration site for Salmonella enteritidis (S. enteritidis) in the gastrointestinal tract. METHODS: Based on the species-specific DNA sequence of S. enteritidis from GenBank, a species-specific real- time, fluorescence-based quantitative polymerase chain reaction (FQ-PCR) was developed for the detection of S. enteritidis. We used this assay to detect genomic DNA of S. enteritidis in the gastrointestinal tract, including duodenum, jejunum, ileum, cecum, colon, rectum, esophagus and stomach, from mice after oral infection. RESULTS: S. enteritidis was consistently detected in all segments of the gastrointestinal tract. The jejunum and ileum were positive at 8 h post inoculation, and the final organ to show a positive result was the stomach at 18 h post inoculation. The copy number of S. enteritidis DNA in each tissue reached a peak at 24-36 h post inoculation, with the jejunum, ileum and cecum containing high concentrations of S. enteritidis, whereas the duodenum, colon, rectum, stomach and esophagus had low concentrations. S. enteritidis began to decrease and vanished at 2 d post inoculation, but it was still present up to 5 d post inoculation in the jejunum, ileum andcecum, without causing apparent symptoms. By 5 d post inoculation, the cecum had significantly higher numbers of S. enteritidis than any of the other areas (P < 0.01), and this appeared to reflect its function as a repository for S. enteritidis. CONCLUSION: The results provided significant data for clarifying the pathogenic mechanism of S. enteritidis in the gastrointestinal tract, and showed that the jejunum, ileum and cecum are the primary sites of invasion in normal mice after oral infection. This study will help to further understanding of the mechanisms of action of S. enteritidis.展开更多
The strength and failure characteristics of most natural rock mass are influenced by discontinues such as fissures, joints, and weak surfaces. In the present study, the strength and failure behavior of ubiquitousjoint...The strength and failure characteristics of most natural rock mass are influenced by discontinues such as fissures, joints, and weak surfaces. In the present study, the strength and failure behavior of ubiquitousjoint rock-like specimens under uniaxial loading have been investigated by DIC(digital image correlation) and discrete element numerical method(PFC2 D). The results are obtained. Firstly, the UCSJof specimens with c = 15° or 30° shows similar tendency while a goes from 0° to 75°. With c = 45° or 60°, the UCSJof specimens increases when a goes from 0° to 30° and decreases after a goes beyond 30°. With c = 75°, the peak UCSJvalue is reached when a = 0°. The UCSJvalue shows an increasing trend when a goes from 60° to 75°. Secondly, the ubiquitous-joint specimens present different failure modes for various levels of a and c(b-a). Based on the experimental results, the failure mode of ubiquitous-joint specimens can be classified into three categories: stepped path failure, failure through parallel plane, and failure through cross plane.展开更多
AIM:To identify and understand the regular distribution pattern for Salmonella enteritidis (S. enteritidis) in the internal organs of mice after an oral challenge over a 3 wk period. METHODS:Assays based on the serova...AIM:To identify and understand the regular distribution pattern for Salmonella enteritidis (S. enteritidis) in the internal organs of mice after an oral challenge over a 3 wk period. METHODS:Assays based on the serovar-specific DNA sequence of S. enteritidis from GenBank, and a serovar-specific real-time, fluorescence-based quantitative polymerase chain reaction (FQ-PCR) were developed for the detection of S. enteritidis. We used this assay to detect genomic DNA of S. enteritidis in the blood and the internal organs, including heart, liver, spleen, kidney, pancreas, and gallbladder, from mice after oral challenge at different time points respectively.RESULTS:The results showed that the spleen was positive at 12 h post inoculation (PI), and the blood was at 14 h PI. The organism was detected in the liver and heart at 16 h PI, the pancreas was positive at 20 h PI, and the final organs to show positive results were the kidney and gallbladder at 22 h PI. The copy number of S. enteritidis DNA in each tissue reached a peak at 24-36 h PI, with the liver and spleen containing high concentrations of S. enteritidis, whereas the blood, heart, kidney, pancreas, and gallbladder had low concentrations. S. enteritidis populations began to decrease and were not detectable at 3 d PI, but were still present up to 12 d PI in the gallbladder, 2 wk for the liver, and 3 wk for the spleen without causing apparent symptoms. CONCLUSION:The results provided significant data for understanding the life cycle of S. enteritidis in the internal organs, and showed that the liver and spleen may be the primary sites for setting itself up as a commensa over a long time after oral challenge. Interestingly, it may be the first time reported that the gallbladder is a site of carriage for S. enteritidis over a 12 d period. This study will help to understand the mechanisms of action of S. enteritidis infection in vivo.展开更多
AIM:To detect Salmonella enteritidis (S. enteritidis) in paraffin slices and antigen location in infected duck tissues. METHODS:Rabbits were immunized with purified bacillus to obtain S. enteritidis-specific antibody,...AIM:To detect Salmonella enteritidis (S. enteritidis) in paraffin slices and antigen location in infected duck tissues. METHODS:Rabbits were immunized with purified bacillus to obtain S. enteritidis-specific antibody, which were then extracted by the caprylic-ammonium sulphate method, purified through High-Q columns. An indirect immuno-fluorescent staining method (IFA) was established to detect the S. enteritidis antigen in paraffin slices. S. enteritidis was detected in each organ tissue of ducklings experimentally infected with S. enteritidis. RESULTS:The gland of Garder, heart, kidney, spleen, liver, brain, ileum, jejunum, bursa of Fabricius from S. enteritidis experimentally infected ducklings were positive or strongly positive, and the S. enteritidis antigen was mainly distributed in the infected cell cytoplasm.CONCLUSION:IFA is an intuitionist, sensitive and specific method in detecting S. enteritidis antigen in paraffin wax slices, and it is a good method in diagnosis and antigen location of S. enteritidis. We also conclude that the gland of Garder, heart, kidney, spleen, liver, ileum, jejunum are target organs in S. enteritidis infections of duck, and S. enteritidis is an intracellular parasitic bacterium.展开更多
Back-streaming neutrons from the spallation target of the China Spallation Neutron Source(CSNS)that emit through the incoming proton channel were exploited to build a white neutron beam facility(the so-called Back-n w...Back-streaming neutrons from the spallation target of the China Spallation Neutron Source(CSNS)that emit through the incoming proton channel were exploited to build a white neutron beam facility(the so-called Back-n white neutron source),which was completed in March 2018.The Back-n neutron beam is very intense,at approximately 29107 n/cm2/s at 55 m from the target,and has a nominal proton beam with a power of 100 kW in the CSNS-I phase and a kinetic energy of 1.6 GeV and a thick tungsten target in multiple slices with modest moderation from the cooling water through the slices.In addition,the excellent energy spectrum spanning from 0.5 eV to 200 MeV,and a good time resolution related tothe time-of-flight measurements make it a typical white neutron source for nuclear data measurements;its overall performance is among that of the best white neutron sources in the world.Equipped with advanced spectrometers,detectors,and application utilities,the Back-n facility can serve wide applications,with a focus on neutron-induced cross-sectional measurements.This article presents an overview of the neutron beam characteristics,the experimental setups,and the ongoing applications at Backn.展开更多
To verify the performance of the neutron total cross-sectional spectrometer, the neutron total cross section of carbon is initially measured in the energy range of 1 eV to 20 MeV using the time-of-flight method. The m...To verify the performance of the neutron total cross-sectional spectrometer, the neutron total cross section of carbon is initially measured in the energy range of 1 eV to 20 MeV using the time-of-flight method. The measurement is performed at the Back-n white neutron source with a 76-m time-of-flight path using the China Spallation Neutron Source. A multilayer fast fission chamber with 235U and 238U is employed as the neutron detector. The diameter and thickness of the natural graphite sample are 70 mm and 40 mm, respectively. Signal waveforms are collected using a data acquisition system. Off-line data processing was used to obtain the neutron time-of-flight spectra and transmissions. The uncertainty of the counting statistics is generally approximately 3% for each bin in the energy range of 1–20 MeV. It is determined that the results for the neutron total cross section of carbon obtained using ^235U cells are in good agreement with the results obtained using 238U cells within limits of statistical uncertainty. Moreover, the measured total cross sections show good agreement with the broadening evaluated data.展开更多
BACKGROUND: V entricular arrhythmia(VA) is one of the most common complications of myocardial infarction(MI), and ventricular tachycardia and fi brillation are the main causes for sudden cardiac death. This study aime...BACKGROUND: V entricular arrhythmia(VA) is one of the most common complications of myocardial infarction(MI), and ventricular tachycardia and fi brillation are the main causes for sudden cardiac death. This study aimed to explore the effect of ramipril on the occurrence of VA and its mechanism after MI in rabbits.METHODS: Twenty-four New Zealand rabbits purchased from the Wuhan Laboratory Animal Research Center were divided into three groups: sham-operated(SHAM) group(n=8), MI group(n=8) and MI with ramipril(RAM) group(n=8). Rabbits in the SHAM group received a median sternotomy without ligation of the left ventricular coronary artery. Rabbits in the MI and RAM groups received a median sternotomy followed by ligation of the left coronary artery. The successful anterior MI was confi rmed by elevation of the ST segment with more than 0.2 mV in lead II and III. After MI, rabbits in the RAM group were fed with intragastric ramipril(1 mg/kg per day) for 12 weeks. Before and 12 weeks after MI in the three groups, ventricular tachycardia or fi brillation(VT/VF) episodes and MAP in cadiocytes of the epicardium, mid-myocardium and endocardium were recorded by a multichannel physiograph. Student's t test and ANOVA were used for statistical analysis.RESULTS: VT/VF episodes were decreased more markedly in the RAM group than in the MI group after 12 weeks(2.6±0.8 vs. 12.4±2.9, P<0.05). Twelve weeks after MI, the duration of repolarization for 90%(APD90) of three-tier ventricular myocytes in the MI group was longer than that before MI(258.2±21.1 vs. 230.1±23.2, 278.0±23.8 vs. 245.8±25.4, 242.6±22.7 vs. 227.0±21.7, P<0.05). However, the APD90 was not signif icantly different at 12 weeks before and after MI in the RAM group(P>0.05). Moreover, the transmural dispersion of repolarization(TDR) was increased more markedly 12 weeks after MI in the MI group than in the SHAM and RAM groups(36.2±10.2 vs. 18.7±6.2, 24.9±8.7, P<0.05). But the TDR was not signifi cantly different between the RAM and SHAM groups(18.7±6.2 vs. 24.9±8.7, P>0.05).CONCLUSION: Ramipril may reduce the incidence of malignant ventricular arrhythmia via improvement of transmembrance repolarization heterogeneity after MI.展开更多
This paper is focused on a wireless energy harvesting system using a rectifying antenna (rectenna). The proposed device consists of a wideband cross-dipole antenna, a microwave low-pass filter and a doubling rectifyin...This paper is focused on a wireless energy harvesting system using a rectifying antenna (rectenna). The proposed device consists of a wideband cross-dipole antenna, a microwave low-pass filter and a doubling rectifying circuit using Shottcky diodes as rectifying elements. Previously, a few of wideband rectennas have been investigated at 1.7 to 2.5 GHz. The originality of this paper is on the new wideband rectenna design which can harvest the ambient radio frequency (RF) power at 1.7 to 2.5 GHz. In this system, a new wideband cross dipole is designed and used to achieve the required bandwidth and duel-polarization. In addition, the voltage doubling rectifying circuit is optimized to achieve the best performance at power density levels 2 which are typical in urban environments. The characteristics of the proposed rectenna over the desired frequency range are investigated, and the integrated rectenna is simulated, made and tested for low input power densities from 5 to 200 μW/cm2. The simulation and measurement results of the rectenna are compared and a good agreement is achieved. The results demonstrate that the maximum rectenna conversion efficiency is nearly 57% around 1.7 GHz and over 20% over the wideband of interest for the incident power density of 120 μW/cm2. It is noted that the impedance matching is one of the main factors affecting the rectenna energy conversion efficiency. This new wideband rectenna has great potential to harvest wireless energy in GSM/3G/4G and ISM 2.4 GHz bands.展开更多
Objective:To study the effect of Xianling Gubao-assisted surgical treatment on postoperative healing, calcium and phosphorus contents as well as bone metabolism in elderly women with Colles fracture.Methods:A total of...Objective:To study the effect of Xianling Gubao-assisted surgical treatment on postoperative healing, calcium and phosphorus contents as well as bone metabolism in elderly women with Colles fracture.Methods:A total of 96 elderly female patients with Colles fracture treated in our hospital between June 2013 and December 2015 were selected and randomly divided into two groups, the observation group of patients received Xianling Gubao capsule combined with manual reduction and plaster external fixation therapy, and control group of patients only received reduction and external fixation therapy. The fracture healing time was followed up after treatment, and 3 months after treatment, serum was collected to determine the content of calcium-phosphorus metabolism indexes and bone metabolism indexes.Results:The fracture healing time of observation group was significantly shorter than that of control group;1 month and 3 months after treatment, serum Ca, P, ALP, IGF-1, PDGF, BGP and PICP levels of both groups were significantly higher than those before treatment while CTX-1, tPINP and TRACP-5b levels were significantly lower than those before treatment;serum Ca, P, ALP, IGF-1, PDGF, BGP and PICP levels of observation group after treatment were significantly higher than those of control group while CTX-1, tPINP and TRACP-5b levels were significantly lower than those of control group.Conclusion:Adjuvant Xianling Gubao capsule therapy can promote the Colles fracture healing in elderly women, also improve calcium-phosphorus metabolism, promote bone formation and inhibit bone resorption.展开更多
There are a lot of researches on qualitative aseismatic measures for buried gas pipeline crossing movable faults.But a few of them are quantitative,especially in the size and shape of the trench.The paper first establ...There are a lot of researches on qualitative aseismatic measures for buried gas pipeline crossing movable faults.But a few of them are quantitative,especially in the size and shape of the trench.The paper first established the finite element model of the strain of buried pipeline crossing a fault which effected by the size and shape of the trench.And it obtained new soil spring stiffness which considered different buried depth,bottom width of trench,trench slope and elastic modulus of soil.The mechanical analysis model of pipeline is established,and the limit state equation of pipeline is fitted.The reliability and sensitivity of the natural gas pipeline under fault action are analysed by a Monte Carlo method,and the error and accuracy are verified.When the pipeline is under tension,the sensitivity from large to small is buried depth,sand friction angle,pipe diameter,pipeline displacement,trench bottom width,trench depth,clay cohesion,trench slope and clay friction angle;when the pipeline is under pressure,the trench depth and clay cohesion have great influence.The findings of this study provide a reference for pipeline design and safety evaluation under fault action.展开更多
Based on the strength reduction method and strain-softening model,a method for progressive failure analysis of strain-softening slopes was presented in this paper.The mutation is more pronounced in strain-softening an...Based on the strength reduction method and strain-softening model,a method for progressive failure analysis of strain-softening slopes was presented in this paper.The mutation is more pronounced in strain-softening analysis,and the mutation of displacement at slope crest was taken as critical failure criterion.An engineering example was provided to demonstrate the validity of the present method.This method was applied to a cut slope in an industry site.The results are as follows:(1) The factor of safety and the critical slip surface obtained by the present method are between those by peak and residual strength.The analysis with peak strength would lead to non-conservative results,but that with residual strength tends to be overly conservative.(2) The thickness of the shear zone considering strain-softening behaviour is narrower than that with non-softening analysis.(3) The failure of slope is the process of the initiation,propagation and connection of potential failure surface.The strength parameters are mobilized to a non-uniform degree while progressive failure occurs in the slope.(4) The factor of safety increases with the increase of residual shear strain threshold and elastic modulus.The failure mode of slope changes from shallow slip to deep slip.Poisson's ratio and dilation angle have little effect on the results.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.12035017)Youth Innovation Promotion Association CAS(No.2023014)Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515010360 and 2022B1515120032).
文摘Nondestructive and noninvasive neutron assays are essential applications of neutron techniques.Neutron resonance transmission analysis(NRTA)is a powerful nondestructive method for investigating the elemental composition of an object.The back-streaming neutron line(Back-n)is a newly built time-of-flight facility at the China Spallation Neutron Source(CSNS)that provides neutrons in the eV to 300 MeV range.A feasibility study of the NRTA method for nuclide identification was conducted at the CSNS Back-n via two test experiments.The results demonstrate that it is feasible to identify different elements and isotopes in samples using the NRTA method at Back-n.This study reveals its potential future applications.
基金supported by the National Natural Science Foundation of China(No.12075237)。
文摘A new measurement method for the spatial distribution of neutron beam flux in boron neutron capture therapy(BNCT)is being developed based on the two-dimensional Micromegas detector.To address the issue of long processing times in traditional offline position reconstruction methods,this paper proposes a field programmable gate array based online position reconstruction method utilizing the micro-time projection chamber principle.This method encapsulates key technical aspects:a self-adaptive serial link technique built upon the dynamical adjustment of the delay chain length,fast sorting,a coordinate-matching technique based on the mapping between signal timestamps and random access memory(RAM)addresses,and a precise start point-merging technique utilizing a circular combined RAM.The performance test of the selfadaptive serial link shows that the bit error rate of the link is better than 10-12 at a confidence level of 99%,ensuring reliable data transmission.The experiment utilizing the readout electronics and Micromegas detector shows a spatial resolution of approximately 1.4 mm,surpassing the current method’s resolution level of 5 mm.The beam experiment confirms that the readout electronics system can obtain the flux spatial distribution of neutron beams online,thus validating the feasibility of the position reconstruction method.The online position reconstruction method avoids traditional methods,such as bubble sorting and traversal searching,simplifies the design of the logic firmware,and reduces the time complexity from O(n2)to O(n).This study contributes to the advancement in measuring neutron beam flux for BNCT.
文摘Objectives: To investigate the effect of lumbar interbody fusion via the oblique lateral approach (OLIF) in the treatment of single level lumbar spondylolisthesis. Methods: Retrospective analysis was made on 32 cases of single level lumbar spondylolisthesis treated by lumbar interbody fusion via the oblique lateral approach from July 2020 to July 2021. 14 males and 18 females;the age was (66.5 ± 11.5) years (55 - 82 years). 1) The operation time, intraoperative blood loss and complications were recorded;2) the scores of visual analog scale. VAS and Oswestry disability index (ODI) of low back pain and lower limb pain were collected before operation and at the last follow-up;by observing the imaging data, the height of the intervertebral space, the anterior convex angle of the intervertebral space, the anterior convex angle of the lumbar spine, the sagittal diameter of the dural sac and the spondylolisthesis were measured. Results: All patients successfully completed the operation, the average operation time was (103.9 ± 21.1) min, the average intraoperative bleeding volume was (72.3 ± 16.4) ml. There was no vascular injury during the operation, no infection occurred in all surgical incisions, and Class I/A healing was achieved. The VAS scores of low back pain and leg pain before operation and at the last follow-up were lower than those before operation, and the difference was statistically significant (P < 0.05);the ODI at the last follow-up was lower than that before operation, and the difference was statistically significant (P < 0.05). At the last follow-up, the height of intervertebral space, the height of intervertebral foramen and the sagittal diameter of dural sac were greater than those before operation, with statistically significant differences (P < 0.05);the spondylolisthesis rate at the last follow-up was lower than that before operation, with a statistically significant difference (P < 0.05). Left thigh surface numbness occurred in 2 cases (6.3%) and disappeared after 1 week;Hip flexion weakness occurred in 1 case (0.03%), which recovered after 12 days;there were no complications such as retroperitoneal hematoma, ureteral injury, retrograde ejaculation, intestinal and lumbar plexus injury. Conclusion: The early clinical effect of OLIF in the treatment of single level lumbar spondylolisthesis is significant. This surgical method is minimally invasive, safe and effective, which can significantly reduce the amount of intraoperative bleeding and reduce the risk of postoperative complications. Its main working principle is to make the annulus fibrosus, posterior longitudinal ligament and ligamentum flavum shrink and recover the height of the intervertebral space through decompression, loosening and stretching of the intervertebral space, so as to achieve the reduction of the slipped vertebral body, increase the height of the intervertebral foramen Enlarge the spinal canal volume and eliminate dynamic compression to play an indirect decompression role, improve the symptoms of low back and leg pain, and reconstruct the stability of the spine through interbody fusion.
基金supported by the National Natural Science Foundation of China(Nos.11675155,11790321,and 12075216)the National Key Research and Development Plan(No.2016YFA0401603).
文摘The ^(232)Th(n,f)cross section is very important in basic nuclear physics and applications based on the Th/U fuel cycle.Using the time-of-flight method and a multi-cell fast-fission ionization chamber,a novel measurement of the^(232)Th(n,f)cross sec-tion relative to^(235)U in the 1–200 MeV range was performed at the China Spallation Neutron Source Back-n white neutron source(Back-n).The fission event-neutron energy spectra of^(232)Th and^(235)U fission cells were measured in the single-bunch mode.Corrected 232Th/235U fission cross-sectional ratios were obtained,and the measurement uncertainties were 2.5–3.7%for energies in the 2–20 MeV range and 3.6–6.2%for energies in the 20–200 MeV range.The^(232)Th(n,f)cross section was obtained by introducing the standard cross section of^(235)U(n,f).The results were compared with those of previous theoreti-cal calculations,measurements,and evaluations.The measured 232Th fission cross section agreed with the main evaluation results in terms of the experimental uncertainty,and 232Th fission resonances were observed in the 1–3 MeV range.The present results provide^(232)Th(n,f)cross-sectional data for the evaluation and design of Th/U cycle nuclear systems.
基金the Water Conservancy Science and Technology Major Project of Hunan Province,China(Project XSKJ2019081-10)the China Scholarship Council(Grant No.202006370344)the First-class Project Special Funding of Yellow River Laboratory,China(Grant No.YRL22YL07).
文摘In the process of engineering construction such as tunnels and slopes,rock mass is frequently subjected to multiple levels of loading and unloading,while previous research ignores the impact of unloading rate on the stability of rock mass.A number of uniaxial multi-level cyclic loading-unloading experiments were conducted to better understand the effect of unloading rate on the deformation behavior,energy evolution,and damage properties of rock-like material.The experimental results demonstrated that the unloading rate and relative cyclic number clearly influence the deformation behavior and energy evo-lution of rock-like samples.In particular,as the relative cyclic number rises,the total strain and reversible strain both increase linearly,while the total energy density,elastic energy density,and dissipated energy density all rise nonlinearly.In contrast,the irreversible strain first decreases quickly,then stabilizes,and finally rises slowly.As the unloading rate increases,the total strain and reversible strain both increase,while the irreversible strain decreases.The dissipated energy damage was examined in light of the aforementioned experimental findings.The accuracy of the proposed damage model,which takes into account the impact of the unloading rate and relative cyclic number,is then confirmed by examining the consistency between the model predicted and the experimental results.The proposed damage model will make it easier to foresee how the multi-level loading-unloading cycles will affect the rock-like materials.
基金Projects(51604299,51274249,51474252)supported by the National Natural Science Foundation of ChinaProject(2016YFC0600706)supported by the State Key Research Development Program of China+4 种基金Project(2015CX005)supported by the Innovation Driven Plan of Central South University,ChinaProject(2016M600636)supported by China Postdoctoral Science FoundationProject supported by the Postdoctoral Science Foundation of Central South University,China
基金Supported by The National Key Technology R&D Program of China, No. 2004B A901A03Program for Chang Jiang Scholars and Innovative Research Team in University, No. IRTO753+2 种基金Program for New Century Excellent Talents in University, No. NCET-04-0906Sichuan Province Basic Research Program, No. 04JY0290061Program for Key Disciplines Construction of Sichuan Province, No. SZD0418
文摘AIM: To identify and understand the regular distribution pattern and primary penetration site for Salmonella enteritidis (S. enteritidis) in the gastrointestinal tract. METHODS: Based on the species-specific DNA sequence of S. enteritidis from GenBank, a species-specific real- time, fluorescence-based quantitative polymerase chain reaction (FQ-PCR) was developed for the detection of S. enteritidis. We used this assay to detect genomic DNA of S. enteritidis in the gastrointestinal tract, including duodenum, jejunum, ileum, cecum, colon, rectum, esophagus and stomach, from mice after oral infection. RESULTS: S. enteritidis was consistently detected in all segments of the gastrointestinal tract. The jejunum and ileum were positive at 8 h post inoculation, and the final organ to show a positive result was the stomach at 18 h post inoculation. The copy number of S. enteritidis DNA in each tissue reached a peak at 24-36 h post inoculation, with the jejunum, ileum and cecum containing high concentrations of S. enteritidis, whereas the duodenum, colon, rectum, stomach and esophagus had low concentrations. S. enteritidis began to decrease and vanished at 2 d post inoculation, but it was still present up to 5 d post inoculation in the jejunum, ileum andcecum, without causing apparent symptoms. By 5 d post inoculation, the cecum had significantly higher numbers of S. enteritidis than any of the other areas (P < 0.01), and this appeared to reflect its function as a repository for S. enteritidis. CONCLUSION: The results provided significant data for clarifying the pathogenic mechanism of S. enteritidis in the gastrointestinal tract, and showed that the jejunum, ileum and cecum are the primary sites of invasion in normal mice after oral infection. This study will help to further understanding of the mechanisms of action of S. enteritidis.
基金funding from Project (Nos.51474249 and 51404179) supported by National Natural Science Foundation of ChinaProject Supported by Innovation Driven Plan of Central South University of China (No.2016CX019)Project (No. SKLGDUEK1405) funded by the Open Projects of State Key Laboratory for Geo-mechanics and Deep Underground Engineering of China University of Mining and Technology,in China
文摘The strength and failure characteristics of most natural rock mass are influenced by discontinues such as fissures, joints, and weak surfaces. In the present study, the strength and failure behavior of ubiquitousjoint rock-like specimens under uniaxial loading have been investigated by DIC(digital image correlation) and discrete element numerical method(PFC2 D). The results are obtained. Firstly, the UCSJof specimens with c = 15° or 30° shows similar tendency while a goes from 0° to 75°. With c = 45° or 60°, the UCSJof specimens increases when a goes from 0° to 30° and decreases after a goes beyond 30°. With c = 75°, the peak UCSJvalue is reached when a = 0°. The UCSJvalue shows an increasing trend when a goes from 60° to 75°. Secondly, the ubiquitous-joint specimens present different failure modes for various levels of a and c(b-a). Based on the experimental results, the failure mode of ubiquitous-joint specimens can be classified into three categories: stepped path failure, failure through parallel plane, and failure through cross plane.
基金The National Key Technology R&D Program of China, No. 2004BA901A03National Scientific and Technical Support Program, No. 2007Z06-017+3 种基金The Cultivation Fund of the Key Scientific and Technical Innovation Project & Ministry of Education of China, No. 706050Program for New Century Excellent Talents in University, No. NCET-04-0906/NCET-06-0818Sichuan Province Basic Research Program, No. 04JY0290061/07JY029-017Program for Key DisciplinesConstruction of Sichuan Province No. SZD0418
文摘AIM:To identify and understand the regular distribution pattern for Salmonella enteritidis (S. enteritidis) in the internal organs of mice after an oral challenge over a 3 wk period. METHODS:Assays based on the serovar-specific DNA sequence of S. enteritidis from GenBank, and a serovar-specific real-time, fluorescence-based quantitative polymerase chain reaction (FQ-PCR) were developed for the detection of S. enteritidis. We used this assay to detect genomic DNA of S. enteritidis in the blood and the internal organs, including heart, liver, spleen, kidney, pancreas, and gallbladder, from mice after oral challenge at different time points respectively.RESULTS:The results showed that the spleen was positive at 12 h post inoculation (PI), and the blood was at 14 h PI. The organism was detected in the liver and heart at 16 h PI, the pancreas was positive at 20 h PI, and the final organs to show positive results were the kidney and gallbladder at 22 h PI. The copy number of S. enteritidis DNA in each tissue reached a peak at 24-36 h PI, with the liver and spleen containing high concentrations of S. enteritidis, whereas the blood, heart, kidney, pancreas, and gallbladder had low concentrations. S. enteritidis populations began to decrease and were not detectable at 3 d PI, but were still present up to 12 d PI in the gallbladder, 2 wk for the liver, and 3 wk for the spleen without causing apparent symptoms. CONCLUSION:The results provided significant data for understanding the life cycle of S. enteritidis in the internal organs, and showed that the liver and spleen may be the primary sites for setting itself up as a commensa over a long time after oral challenge. Interestingly, it may be the first time reported that the gallbladder is a site of carriage for S. enteritidis over a 12 d period. This study will help to understand the mechanisms of action of S. enteritidis infection in vivo.
基金the National Key Technology R&D Program of China, No. 2004BA 901A 03National Scientific and Sechnical Support Program, No. 2007Z06-017+3 种基金The Cultvation Fund of the Key Scientific and Technical Innovation Project & Ministry of Education of China, No. 706050Program for New Century Excellent Talents in University, No. NCET-04-0906/NCET-06-0818Sichuan Province Basic Research Program, No. 04JY0290061/07JY029-017Program for Key Disciplines Construction of Sichuan Province No. SZD0418
文摘AIM:To detect Salmonella enteritidis (S. enteritidis) in paraffin slices and antigen location in infected duck tissues. METHODS:Rabbits were immunized with purified bacillus to obtain S. enteritidis-specific antibody, which were then extracted by the caprylic-ammonium sulphate method, purified through High-Q columns. An indirect immuno-fluorescent staining method (IFA) was established to detect the S. enteritidis antigen in paraffin slices. S. enteritidis was detected in each organ tissue of ducklings experimentally infected with S. enteritidis. RESULTS:The gland of Garder, heart, kidney, spleen, liver, brain, ileum, jejunum, bursa of Fabricius from S. enteritidis experimentally infected ducklings were positive or strongly positive, and the S. enteritidis antigen was mainly distributed in the infected cell cytoplasm.CONCLUSION:IFA is an intuitionist, sensitive and specific method in detecting S. enteritidis antigen in paraffin wax slices, and it is a good method in diagnosis and antigen location of S. enteritidis. We also conclude that the gland of Garder, heart, kidney, spleen, liver, ileum, jejunum are target organs in S. enteritidis infections of duck, and S. enteritidis is an intracellular parasitic bacterium.
基金This work was jointly supported by the National Key Research and Development Program of China(No.2016YFA0401600)National Natural Science Foundation of China(Nos.11235012 and 12035017)+1 种基金the CSNS Engineering Projectthe Back-n Collaboration Consortium fund。
文摘Back-streaming neutrons from the spallation target of the China Spallation Neutron Source(CSNS)that emit through the incoming proton channel were exploited to build a white neutron beam facility(the so-called Back-n white neutron source),which was completed in March 2018.The Back-n neutron beam is very intense,at approximately 29107 n/cm2/s at 55 m from the target,and has a nominal proton beam with a power of 100 kW in the CSNS-I phase and a kinetic energy of 1.6 GeV and a thick tungsten target in multiple slices with modest moderation from the cooling water through the slices.In addition,the excellent energy spectrum spanning from 0.5 eV to 200 MeV,and a good time resolution related tothe time-of-flight measurements make it a typical white neutron source for nuclear data measurements;its overall performance is among that of the best white neutron sources in the world.Equipped with advanced spectrometers,detectors,and application utilities,the Back-n facility can serve wide applications,with a focus on neutron-induced cross-sectional measurements.This article presents an overview of the neutron beam characteristics,the experimental setups,and the ongoing applications at Backn.
基金supported by the National Key Research and Development Plan(No.2016YFA0401603)the National Natural Science Foundation of China(No.11675155)
文摘To verify the performance of the neutron total cross-sectional spectrometer, the neutron total cross section of carbon is initially measured in the energy range of 1 eV to 20 MeV using the time-of-flight method. The measurement is performed at the Back-n white neutron source with a 76-m time-of-flight path using the China Spallation Neutron Source. A multilayer fast fission chamber with 235U and 238U is employed as the neutron detector. The diameter and thickness of the natural graphite sample are 70 mm and 40 mm, respectively. Signal waveforms are collected using a data acquisition system. Off-line data processing was used to obtain the neutron time-of-flight spectra and transmissions. The uncertainty of the counting statistics is generally approximately 3% for each bin in the energy range of 1–20 MeV. It is determined that the results for the neutron total cross section of carbon obtained using ^235U cells are in good agreement with the results obtained using 238U cells within limits of statistical uncertainty. Moreover, the measured total cross sections show good agreement with the broadening evaluated data.
基金supported by a grant from the Natural Science Foundation of Hubei(2007ABA288)
文摘BACKGROUND: V entricular arrhythmia(VA) is one of the most common complications of myocardial infarction(MI), and ventricular tachycardia and fi brillation are the main causes for sudden cardiac death. This study aimed to explore the effect of ramipril on the occurrence of VA and its mechanism after MI in rabbits.METHODS: Twenty-four New Zealand rabbits purchased from the Wuhan Laboratory Animal Research Center were divided into three groups: sham-operated(SHAM) group(n=8), MI group(n=8) and MI with ramipril(RAM) group(n=8). Rabbits in the SHAM group received a median sternotomy without ligation of the left ventricular coronary artery. Rabbits in the MI and RAM groups received a median sternotomy followed by ligation of the left coronary artery. The successful anterior MI was confi rmed by elevation of the ST segment with more than 0.2 mV in lead II and III. After MI, rabbits in the RAM group were fed with intragastric ramipril(1 mg/kg per day) for 12 weeks. Before and 12 weeks after MI in the three groups, ventricular tachycardia or fi brillation(VT/VF) episodes and MAP in cadiocytes of the epicardium, mid-myocardium and endocardium were recorded by a multichannel physiograph. Student's t test and ANOVA were used for statistical analysis.RESULTS: VT/VF episodes were decreased more markedly in the RAM group than in the MI group after 12 weeks(2.6±0.8 vs. 12.4±2.9, P<0.05). Twelve weeks after MI, the duration of repolarization for 90%(APD90) of three-tier ventricular myocytes in the MI group was longer than that before MI(258.2±21.1 vs. 230.1±23.2, 278.0±23.8 vs. 245.8±25.4, 242.6±22.7 vs. 227.0±21.7, P<0.05). However, the APD90 was not signif icantly different at 12 weeks before and after MI in the RAM group(P>0.05). Moreover, the transmural dispersion of repolarization(TDR) was increased more markedly 12 weeks after MI in the MI group than in the SHAM and RAM groups(36.2±10.2 vs. 18.7±6.2, 24.9±8.7, P<0.05). But the TDR was not signifi cantly different between the RAM and SHAM groups(18.7±6.2 vs. 24.9±8.7, P>0.05).CONCLUSION: Ramipril may reduce the incidence of malignant ventricular arrhythmia via improvement of transmembrance repolarization heterogeneity after MI.
文摘This paper is focused on a wireless energy harvesting system using a rectifying antenna (rectenna). The proposed device consists of a wideband cross-dipole antenna, a microwave low-pass filter and a doubling rectifying circuit using Shottcky diodes as rectifying elements. Previously, a few of wideband rectennas have been investigated at 1.7 to 2.5 GHz. The originality of this paper is on the new wideband rectenna design which can harvest the ambient radio frequency (RF) power at 1.7 to 2.5 GHz. In this system, a new wideband cross dipole is designed and used to achieve the required bandwidth and duel-polarization. In addition, the voltage doubling rectifying circuit is optimized to achieve the best performance at power density levels 2 which are typical in urban environments. The characteristics of the proposed rectenna over the desired frequency range are investigated, and the integrated rectenna is simulated, made and tested for low input power densities from 5 to 200 μW/cm2. The simulation and measurement results of the rectenna are compared and a good agreement is achieved. The results demonstrate that the maximum rectenna conversion efficiency is nearly 57% around 1.7 GHz and over 20% over the wideband of interest for the incident power density of 120 μW/cm2. It is noted that the impedance matching is one of the main factors affecting the rectenna energy conversion efficiency. This new wideband rectenna has great potential to harvest wireless energy in GSM/3G/4G and ISM 2.4 GHz bands.
文摘Objective:To study the effect of Xianling Gubao-assisted surgical treatment on postoperative healing, calcium and phosphorus contents as well as bone metabolism in elderly women with Colles fracture.Methods:A total of 96 elderly female patients with Colles fracture treated in our hospital between June 2013 and December 2015 were selected and randomly divided into two groups, the observation group of patients received Xianling Gubao capsule combined with manual reduction and plaster external fixation therapy, and control group of patients only received reduction and external fixation therapy. The fracture healing time was followed up after treatment, and 3 months after treatment, serum was collected to determine the content of calcium-phosphorus metabolism indexes and bone metabolism indexes.Results:The fracture healing time of observation group was significantly shorter than that of control group;1 month and 3 months after treatment, serum Ca, P, ALP, IGF-1, PDGF, BGP and PICP levels of both groups were significantly higher than those before treatment while CTX-1, tPINP and TRACP-5b levels were significantly lower than those before treatment;serum Ca, P, ALP, IGF-1, PDGF, BGP and PICP levels of observation group after treatment were significantly higher than those of control group while CTX-1, tPINP and TRACP-5b levels were significantly lower than those of control group.Conclusion:Adjuvant Xianling Gubao capsule therapy can promote the Colles fracture healing in elderly women, also improve calcium-phosphorus metabolism, promote bone formation and inhibit bone resorption.
基金financial support by China Petroleum Science&Technology Innovation Fund(2017D-50070606):Reliability research of large diameter and high steel natural gas pipeline under fault action。
文摘There are a lot of researches on qualitative aseismatic measures for buried gas pipeline crossing movable faults.But a few of them are quantitative,especially in the size and shape of the trench.The paper first established the finite element model of the strain of buried pipeline crossing a fault which effected by the size and shape of the trench.And it obtained new soil spring stiffness which considered different buried depth,bottom width of trench,trench slope and elastic modulus of soil.The mechanical analysis model of pipeline is established,and the limit state equation of pipeline is fitted.The reliability and sensitivity of the natural gas pipeline under fault action are analysed by a Monte Carlo method,and the error and accuracy are verified.When the pipeline is under tension,the sensitivity from large to small is buried depth,sand friction angle,pipe diameter,pipeline displacement,trench bottom width,trench depth,clay cohesion,trench slope and clay friction angle;when the pipeline is under pressure,the trench depth and clay cohesion have great influence.The findings of this study provide a reference for pipeline design and safety evaluation under fault action.
基金Project supported by the National Natural Science Foundation of China (No. 10972238)the Scholarship Award for Excellent Doctoral Student Granted by Ministry of Educationthe Transportation Science and Technology Projects of Hunan Province (No. 201003),China
文摘Based on the strength reduction method and strain-softening model,a method for progressive failure analysis of strain-softening slopes was presented in this paper.The mutation is more pronounced in strain-softening analysis,and the mutation of displacement at slope crest was taken as critical failure criterion.An engineering example was provided to demonstrate the validity of the present method.This method was applied to a cut slope in an industry site.The results are as follows:(1) The factor of safety and the critical slip surface obtained by the present method are between those by peak and residual strength.The analysis with peak strength would lead to non-conservative results,but that with residual strength tends to be overly conservative.(2) The thickness of the shear zone considering strain-softening behaviour is narrower than that with non-softening analysis.(3) The failure of slope is the process of the initiation,propagation and connection of potential failure surface.The strength parameters are mobilized to a non-uniform degree while progressive failure occurs in the slope.(4) The factor of safety increases with the increase of residual shear strain threshold and elastic modulus.The failure mode of slope changes from shallow slip to deep slip.Poisson's ratio and dilation angle have little effect on the results.
