van der Waals(vdW)heterostructures constructed by lowdimensional(0D,1D,and 2D)materials are emerging as one of the most appealing systems in next-generation flexible photodetection.Currently,hand-stacked vdW-type phot...van der Waals(vdW)heterostructures constructed by lowdimensional(0D,1D,and 2D)materials are emerging as one of the most appealing systems in next-generation flexible photodetection.Currently,hand-stacked vdW-type photodetectors are not compatible with large-areaarray fabrication and show unimpressive performance in self-powered mode.Herein,vertical 1D GaN nanorods arrays(NRAs)/2D MoS_(2)/PEDOT:PSS in wafer scale have been proposed for self-powered flexible photodetectors arrays firstly.The as-integrated device without external bias under weak UV illumination exhibits a competitive responsivity of 1.47 A W^(−1)and a high detectivity of 1.2×10^(11)Jones,as well as a fast response speed of 54/71μs,thanks to the strong light absorption of GaN NRAs and the efficient photogenerated carrier separation in type-II heterojunction.Notably,the strain-tunable photodetection performances of device have been demonstrated.Impressively,the device at−0.78%strain and zero bias reveals a significantly enhanced photoresponse with a responsivity of 2.47 A W^(−1),a detectivity of 2.6×10^(11)Jones,and response times of 40/45μs,which are superior to the state-of-the-art self-powered flexible photodetectors.This work presents a valuable avenue to prepare tunable vdWs heterostructures for self-powered flexible photodetection,which performs well in flexible sensors.展开更多
The lunar surface and its deep layers contain abundant resources and valuable information resources,the exploration and exploitation of which are important for the sustainable development of the human economy and soci...The lunar surface and its deep layers contain abundant resources and valuable information resources,the exploration and exploitation of which are important for the sustainable development of the human economy and society.Technological exploration and research in the field of deep space science,especially lunar-based exploration,is a scientific strategy that has been pursued in China and worldwide.Drilling and sampling are key to accurate exploration of the desirable characteristics of deep lunar resources.In this study,an in-situ condition preserved coring(ICP-Coring)and analysis system,which can be used to test drilling tools and develop effective sampling strategies,was designed.The key features of the system include:(1)capability to replicate the extreme temperature fluctuations of the lunar environment(-185 to 200℃)with intelligent temperature control;(2)ability to maintain a vacuum environment at a scale of 10^(-3) Pa,both under unloaded conditions within Ф580 mm×1000 mm test chamber,and under loaded conditions using Ф400 mm×800 mm lunar rock simulant;(3)application of axial pressures up to 4 MPa and confining pressures up to 3.5 MPa;(4)sample rotation at any angle with a maximum sampling length of 800 mm;and(5)multiple modes of rotary-percussive drilling,controlled by penetration speed and weight on bit(WOB).Experimental studies on the drilling characteristics in the lunar rock simulant-loaded state under different drill bit-percussive-vacuum environment configurations were conducted.The results show that the outgassing rate of the lunar soil simulant is greater than that of the lunar rock simulant and that a low-temperature environment contributes to a reduced vacuum of the lunar-based simulated environment.The rotary-percussive drilling method effectively shortens the sampling time.With increasing sampling depth,the temperature rise of the drilling tools tends to rapidly increase,followed by slow growth or steady fluctuations.The temperature rise energy accumulation of the drill bits under vacuum is more significant than that under atmospheric pressure,approximately 1.47 times higher.The real-time monitored drilling pressure,penetration speed and rotary torque during drilling serve as parameters for discriminating the drilling status.The results of this research can provide a scientific basis for returning samples from lunar rock in extreme lunar-based environments.展开更多
In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterpart...In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterparts.The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications.In this context,the atomic substitution method has emerged as a favorable approach.It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely,crystal structures,and inherent properties of the resulting materials.In this review,we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional,one-dimensional and two-dimensional TMC materials.The effects of substituting elements,substitution ratios,and substitution positions on the structures and morphologies of resulting material are discussed.The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided,emphasizing the role of atomic substitution in achieving these advancements.Finally,challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.展开更多
Memristors are extensively used to estimate the external electromagnetic stimulation and synapses for neurons.In this paper,two distinct scenarios,i.e.,an ideal memristor serves as external electromagnetic stimulation...Memristors are extensively used to estimate the external electromagnetic stimulation and synapses for neurons.In this paper,two distinct scenarios,i.e.,an ideal memristor serves as external electromagnetic stimulation and a locally active memristor serves as a synapse,are formulated to investigate the impact of a memristor on a two-dimensional Hindmarsh-Rose neuron model.Numerical simulations show that the neuronal models in different scenarios have multiple burst firing patterns.The introduction of the memristor makes the neuronal model exhibit complex dynamical behaviors.Finally,the simulation circuit and DSP hardware implementation results validate the physical mechanism,as well as the reliability of the biological neuron model.展开更多
An all-fiber polarization maintaining high-power laser system operating at 1.7 μm based on the Ramaninduced soliton self-frequency shifting effect is demonstrated. The entirely fiberized system is built by erbiumdope...An all-fiber polarization maintaining high-power laser system operating at 1.7 μm based on the Ramaninduced soliton self-frequency shifting effect is demonstrated. The entirely fiberized system is built by erbiumdoped oscillator and two-stage amplifiers with polarization maintaining commercial silica fibers and devices, which can provide robust and stable soliton generation. High-power soliton laser with the average power of 0.28 W,the repetition rate of 42.7 MHz, and pulse duration of 515 fs is generated directly from the main amplifier.Our experiment provides a feasible method for high-power all-fiber polarization maintaining femtosecond laser generation working at 1.7 μm.展开更多
Background Individuals with diabetes have a significantly higher risk of developing chronic kidney disease(CKD)and higher levels of social isolation and loneliness compared with those without diabetes.Recently,the Ame...Background Individuals with diabetes have a significantly higher risk of developing chronic kidney disease(CKD)and higher levels of social isolation and loneliness compared with those without diabetes.Recently,the American Heart Association highlighted the importance of considering social determinants of health(SDOH)in conjunction with traditional risk factors in patients with diabetes.Aims To investigate the associations of loneliness and social isolation with incident CKD risk in patients with diabetes in the UK Biobank.Methods A total of 18972 patients with diabetes were included in this prospective study.Loneliness and Social Isolation Scales were created based on self-reported factors.An adjusted Cox proportional hazard model was used to investigate the associations of loneliness and social isolation with CKD risk among patients with diabetes.The relative importance in predicting CKD was also calculated alongside traditional risk factors.Results During a median follow-up of 10.8 years,1127 incident CKD cases were reported.A higher loneliness scale,but not social isolation,was significantly associated with a 25%higher risk of CKD,independent of traditional risk factors,among patients with diabetes.Among the individual loneliness factors,the sense of feeling lonely emerged as the primary contributing factor to the elevated risk of CKD.Compared with individuals not experiencing feelings of loneliness,those who felt lonely exhibited a 22%increased likelihood of developing CKD.In addition,feeling lonely demonstrated greater relative importance of predicting CKD compared with traditional risk factors such as body mass index,smoking,physical activity and diet.Conclusions This study indicates the significant relationship between loneliness and CKD risk among patients with diabetes,highlighting the need to address SDOH in preventing CKD in this population.展开更多
The exploration and development of oil and gas resources have shifted from shallow to deep and ultradeep.The difficulty of rock breaking has also increased,introducing new challenges to traditional rock-breaking techn...The exploration and development of oil and gas resources have shifted from shallow to deep and ultradeep.The difficulty of rock breaking has also increased,introducing new challenges to traditional rock-breaking technology.Hence,there is an urgent need to develop new rock-breaking technologies to improve the development efficiency of deep oil and gas resources.Therefore,this study focused on the new microwave rock-breaking technology and conducted experimental and numerical simulation research on typical deep,hard rock granite.The research results showed that granite in the microwave field exhibited high-temperature melting and fracture,and the highest temperature could reach 550°C.Under the irradiation of circulating microwaves,a minimum irradiation time threshold of 3 min was needed to cause irreversible damage to the rock.The numerical simulation results showed that the interaction of thermal stress and in situ stress would cause the inside of the rock stratum to separate into a disturbed deterioration area,disturbed unloading area and initial stress area.These results are expected to provide the necessary technical guidance and theoretical support for the research and development of high-efficiency rock-breaking drilling for deep hard rock.展开更多
With the increasing scarcity of Earth’s resources and the development of space science and technology,the exploration, development, and utilization of deep space-specific material resources(minerals, water ice, volat...With the increasing scarcity of Earth’s resources and the development of space science and technology,the exploration, development, and utilization of deep space-specific material resources(minerals, water ice, volatile compounds, etc.) are not only important to supplement the resources and reserves on Earth but also provide a material foundation for establishing extraterrestrial research bases. To achieve large depth in-situ condition-preserved coring(ICP-Coring) in the extreme lunar environment, first, lunar rock simulant was selected(SZU-1), which has a material composition, element distribution, and physical and mechanical properties that are approximately equivalent to those of lunar mare basalt. Second, the influence of the lunar-based in-situ environment on the phase, microstructure, and thermal physical properties(specific heat capacity, thermal conductivity, thermal diffusivity, and thermal expansion coefficient)of SZU-1 was explored and compared with the measured lunar rock data. It was found that in an air atmosphere, low temperature has a more pronounced effect on the relative content of olivine than other temperatures, while in a vacuum atmosphere, the relative contents of olivine and anorthite are significantly affected only at temperatures of approximately-20 and 200 ℃. When the vacuum level is less than100 Pa, the contribution of air conduction can be almost neglected, whereas it becomes dominant above this threshold. Additionally, as the testing temperature increases, the surface of SZU-1 exhibits increased microcracking, fracture opening, and unevenness, while the specific heat capacity, thermal conductivity,and thermal expansion coefficient show nonlinear increases. Conversely, the thermal diffusivity exhibits a nonlinear decreasing trend. The relationship between thermal conductivity, thermal diffusivity, and temperature can be effectively described by an exponential function(R^(2)>0.98). The research results are consistent with previous studies on real lunar rocks. These research findings are expected to be applied in the development of the test and analysis systems of ICP-Coring in a lunar environment and the exploration of the mechanism of machine-rock interaction in the in-situ drilling and coring process.展开更多
A severe accident in a marine nuclear reactor leads to radionuclide leakage,which causes hidden dangers to workers and has adverse effects of environmental pollution.It is necessary to propose a novel approach to radi...A severe accident in a marine nuclear reactor leads to radionuclide leakage,which causes hidden dangers to workers and has adverse effects of environmental pollution.It is necessary to propose a novel approach to radionuclide diffusion in a confined environment after a severe accident in a marine nuclear reactor.Therefore,this study proposes a new method for the severe accident analysis program MELCOR coupled with computational fluid dynamics scSTREAM to study radioactive diffusion in severe accidents.The radionuclide release fraction and temperature calculated by MELCOR were combined with the scSTREAM calculations to study the radionuclide diffusion behavior and the phenomenon of radionuclide diffusion in different space environments of the reactor under the conditions of varying wind velocities of the ventilation system and diffusion speed.The results show that the wind velocity of the ventilation system is very small or zero,and the turbulent diffusion of radionuclides is not obvious and diffuses slowly in the form of condensation sedimentation and gravity settlement.When the wind speed of the ventilation system increases,the flow of radionuclides meets the wall and forms eddy currents,affecting the time variation of radionuclides diffusing into chamber 2.The wind velocity of the ventilation system and the diffusion speed has opposite effects on the time variation trend of radionuclide diffusion into the four chambers.展开更多
Objective To investigate the image quality, radiation dose and diagnostic value of the low-tube-voltage high-pitch dual-source computed tomography(DSCT) with sinogram affirmed iterative reconstruction(SAFIRE) for non-...Objective To investigate the image quality, radiation dose and diagnostic value of the low-tube-voltage high-pitch dual-source computed tomography(DSCT) with sinogram affirmed iterative reconstruction(SAFIRE) for non-enhanced abdominal and pelvic scans. Methods This institutional review board-approved prospective study included 64 patients who gave written informed consent for additional abdominal and pelvic scan with DSCT in the period from November to December 2012. The patients underwent standard non-enhanced CT scans(protocol 1) [tube voltage of 120 k Vp/pitch of 0.9/filtered back-projection(FBP) reconstruction] followed by high-pitch non-enhanced CT scans(protocol 2)(100 k Vp/3.0/SAFIRE). The total scan time, mean CT number, signal-to-noise ratio(SNR), image quality, lesion detectability and radiation dose were compared between the two protocols. Results The total scan time of protocol 2 was significantly shorter than that of protocol 1(1.4±0.1 seconds vs. 7.6±0.6 seconds, P<0.001). There was no significant difference between protocol 1 and protocol 2 in mean CT number of all organs(liver, 55.4±6.3 HU vs. 56.1±6.8 HU, P=0.214; pancreas, 43.6±5.9 HU vs. 43.7±5.8 HU, P=0.785; spleen, 47.9±3.9 HU vs. 49.4±4.3 HU, P=0.128; kidney, 32.2±2.3 HU vs. 33.1±2.3 HU, P=0.367; abdominal aorta, 44.8±5.6 HU vs. 45.0±5.5 HU, P=0.499; psoas muscle, 50.7±4.1 HU vs. 50.3±4.5 HU, P=0.279). SNR on images of protocol 2 was higher than that of protocol 1(liver, 5.0±1.2 vs. 4.5±1.1, P<0.001; pancreas, 4.0±1.0 vs. 3.6±0.8, P<0.001; spleen, 4.7±1.0 vs. 4.1±0.9, P<0.001; kidney, 3.1±0.6 vs. 2.8±0.6, P<0.001; abdominal aorta, 4.1±1.0 vs. 3.8±1.0, P<0.001; psoas muscle, 4.5±1.1 vs. 4.3±1.2, P=0.012). The overall image noise of protocol 2 was lower than that of protocol1(9.8±3.1 HU vs. 11.1±3.0 HU, P<0.001). Image quality of protocol 2 was good but lower than that of protocol 1(4.1±0.7 vs. 4.6±0.5, P<0.001). Protocol 2 perceived 229 of 234 lesions(97.9%) that were detected in protocol 1 in the abdomen and pelvis. Radiation dose of protocol 2 was lower than that of protocol 1(4.4±0.4 m Sv vs. 7.3±2.4 m Sv, P<0.001) and the mean dose reduction was 41.4%. Conclusion The high-pitch DSCT with SAFIRE can shorten scan time and reduce radiation dose while preserving image quality in non-enhanced abdominal and pelvic scans.展开更多
Objective To measure volume and other parameters of normal adrenal glands in Chinese adults with 64-slice multidetector CT, to evaluate the relationship of volume result with age, sex and body size, and to explore the...Objective To measure volume and other parameters of normal adrenal glands in Chinese adults with 64-slice multidetector CT, to evaluate the relationship of volume result with age, sex and body size, and to explore the correlations between adrenal volume and other measurements. Methods This study was based on 125 acquired contrast-enhanced upper abdominal CT scans performed with a 64-slice CT. The final study group consisted of 81 patients (49 males, 32 females). Portal venous phase images were studied for the measurements. Both the reconstruction interval and thickness were 1.5 mm. Each adrenal gland was outlined manually with computer-assistant technology to calculate its volume. The maximal sectional area, length, width and thickness of each adrenal gland were also measured. Results The mean age of total population was 47.9±13.0 (range: 20-76) years. The left, right, and total adrenal gland volumes were 4.23±0.74 (range: 2.85-5.83) cm 3 , 4.26±0.86 (2.59-6.56) cm 3 , and 8.50±1.40 (5.80-11.39) cm 3 , respectively. These volumes increased with weight (r=0.381, 0.389, and 0.437 respectively, all P<0.001), height (r=0.386, P<0.001; r=0.297, P=0.007; r=0.384, P<0.001) and body surface area (r=0.406, 0.392, and 0.452, all P<0.001). There was no significant difference in left, right or total adrenal volume with regard to sex after applying General Linear Model procedure to reduce the impact of weight (F=1.304, 0.064, and 0.597, all P>0.05), nor did volume change significantly with age (r=-0.033, -0.014, and -0.026, all P>0.05). Nearly all descriptors of bilateral adrenal glands correlated with ipsilateral volume except thickness (r=-0.027, P=0.814) and width (r=0.166, P=0.138) in the left side. Among these parameters, length had a stronger correlation with volume than others in the both left (r=0.412, P<0.001) and right (r=0.516, P<0.001) adrenal glands. Conclusion Our study has defined the volume distribution and other parameters of normal adrenal glands in Chinese adults, which provide a baseline for future studies.展开更多
Porous carbon spheres are prepared by direct carbonization of potassium salt of resorcinol-formaldehyde resin spheres, and are investigated as COadsorbents. It is found that the prepared carbon materials still maintai...Porous carbon spheres are prepared by direct carbonization of potassium salt of resorcinol-formaldehyde resin spheres, and are investigated as COadsorbents. It is found that the prepared carbon materials still maintain the typical spherical shapes after the activation, and have highly developed ultra-microporosity with uniform pore size, indicating that almost the activation takes place in the interior of the polymer spheres. The narrow-distributed ultra-micropores are attributed to the "in-situ homogeneous activation"effect produced by the mono-dispersed potassium ions as a form of -OK groups in the bulk of polymer spheres. The CS-1 sample prepared under a KOH/resins weight ratio of 1 shows a very high COcapture capacity of 4.83 mmol/g and good CO/Nselectivity of7-45. We believe that the presence of a welldeveloped ultra-microporosity is responsible for excellent COsorption performance at room temperature and ambient pressure.展开更多
Objective To retrospectively evaluate the effects of saline administration following contrast material injection, abdominal compression and two delay phase acquisition on image quality improvement of computed tomograp...Objective To retrospectively evaluate the effects of saline administration following contrast material injection, abdominal compression and two delay phase acquisition on image quality improvement of computed tomographic urography (CTU). Methods Medical records and informed consents of patients were obtained. In totally 122 patients (50 men, 72 women), two delay phase images with CTU were performed. Scans began simultaneously with a contrast bolus injection of 100 mL (300 mgI/mL) followed by a saline bolus injection of 100 mL at a rate of 5 mL/s. Two delay phase images were taken at 400 and 550 seconds for each patient. Examinations were taken by using abdominal compression or not. The distention and opacification of the urinary tract were evaluated by two interpreters together on transverse images and post-processing images. Effects of four techniques (saline administration and abdominal compression, saline administration only, compression only, and neither saline administration nor compression) and two delay phase acquisition on image quality improvement were analysed by using ANOVA and Chi-square test. Results Saline administration improved opacification (P<0.05) and increased overall image quality (P<0.01) of the intrarenal collecting system and proximal ureter. Abdominal compression (P<0.05) and delayed phase image acquisition of 550 seconds (P<0.01) all improved distention of the intrarenal collecting system and proximal ureter but did not improve opacification. No statistically significant effects on the distal ureter were found. However, there were more visualized distal ureteral segments with the longer imaging delay. Conclusion Saline administration, abdominal compression and longer imaging delays are all effective in improving image quality of 64-detector row CTU.展开更多
Objectives To investigate whether a longer time period of gadolinium ethoxybenzyl diethylenetriaminepen-taacetic add(Gd-EOB-DTPA)-enhanced T1 mapping scanning,as well as dynamic contrast-enhanced(DCE)and multiple hepa...Objectives To investigate whether a longer time period of gadolinium ethoxybenzyl diethylenetriaminepen-taacetic add(Gd-EOB-DTPA)-enhanced T1 mapping scanning,as well as dynamic contrast-enhanced(DCE)and multiple hepatobiliary phase magnetic resonance imaging(MRI)have the potential to provide information about liver function in rats with liver fibrosis.Methods Forty rats were divided into the carbon tetrachloride-induced hepatic injury groups[carbon tetrachloride for four(n=14),eight(n=8),or twelve(n=8)weeks]and the control group(n=10).Gd-EOB-DTPA-enhanced MRI was performed including T1-mapping(delayed to 50 min),DCE,and multiple hepatobiliary phases.Indocyanine green retention rate at 15 min(ICG-R15)was determined.Parameters such as T1 reduction rate(△T1),elimination half-life of △T1(T_(△T1 1/2)),relative enhancement(RE),time to maximum RE(T_(max)),and perfusion parameters were calculated.Pearson correlation analysis was used for correlation analysis between ICG-R15 and each MRI indices.Results △T1 at 30,40,and 50 min showed significant positive correlations with ICG-R15(r=0.784,0.653,0.757,P=0.007,0.041,0.030).T_(△T1 1/2) showed a significant positive correlation with ICG-R15(r=0.685,P=0.029).showed a significant positive correlation with ICG-R15(r=0.532,P=0.019).Conclusions △T1 in the late hepatobiliary phase and T_(△T1 1/2) exhibited moderate correlations with liver function.The longer time period of Gd-EOB-DTPA-enhanced Tl mapping scanning,as well as DCE and multiple hepatobiliary phases,may be of some value for estimating liver function in rats with liver fibrosis.展开更多
Numerous techniques have been developed to determine the bioavailability of minerals.Each method has specific detection objects with certain procedures to assure the results.This review focuses on a comprehensivecompa...Numerous techniques have been developed to determine the bioavailability of minerals.Each method has specific detection objects with certain procedures to assure the results.This review focuses on a comprehensivecomparison of the applications,advantages,and critical control points of these techniques.The commonly used approaches for assessing mineral bioavailability can be divided into three categories-chemical methods,in vitro models and in vivo tests.Chemical methods are first developed,and mainly simulating the digestion environment to give a rough prediction of mineral bioavailability.In vitro models mainly used different cells to simulate the process and environment of food digestion to assess the availability of minerals.In vivo tests are employing complex models to observe the bioavailability of minerals after complicated digestive process in animal models or human volunteers.This review summarizes the critical points of establishment of these relevant models,compares the advantages and limitations among three categories.Although no single bioavailability method is ideal for all micronutrients,certain methods under proper operation can indeed be employed to minimize the differences between simulated results and reality for effective evaluation of the bioavailability of minerals.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFB3604500,No.2022YFB3604501)the National Natural Science Foundation of China(No.52172141)the Technology Development Project of Shanxi-Zheda Institude of Advanced Materials and Chemical Engineering(No.2022SX-TD017).
文摘van der Waals(vdW)heterostructures constructed by lowdimensional(0D,1D,and 2D)materials are emerging as one of the most appealing systems in next-generation flexible photodetection.Currently,hand-stacked vdW-type photodetectors are not compatible with large-areaarray fabrication and show unimpressive performance in self-powered mode.Herein,vertical 1D GaN nanorods arrays(NRAs)/2D MoS_(2)/PEDOT:PSS in wafer scale have been proposed for self-powered flexible photodetectors arrays firstly.The as-integrated device without external bias under weak UV illumination exhibits a competitive responsivity of 1.47 A W^(−1)and a high detectivity of 1.2×10^(11)Jones,as well as a fast response speed of 54/71μs,thanks to the strong light absorption of GaN NRAs and the efficient photogenerated carrier separation in type-II heterojunction.Notably,the strain-tunable photodetection performances of device have been demonstrated.Impressively,the device at−0.78%strain and zero bias reveals a significantly enhanced photoresponse with a responsivity of 2.47 A W^(−1),a detectivity of 2.6×10^(11)Jones,and response times of 40/45μs,which are superior to the state-of-the-art self-powered flexible photodetectors.This work presents a valuable avenue to prepare tunable vdWs heterostructures for self-powered flexible photodetection,which performs well in flexible sensors.
基金supported by the National Natural Science Foundation of China(Nos.52225403,U2013603,52434004,and 52404365)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2019ZT08G315)+2 种基金the Shenzhen National Science Fund for Distinguished Young Scholars(No.RCJC20210706091948015)the National Key Research and Development Program of China(2023YFF0615404)the Scientific Instrument Developing Project of Shenzhen University。
文摘The lunar surface and its deep layers contain abundant resources and valuable information resources,the exploration and exploitation of which are important for the sustainable development of the human economy and society.Technological exploration and research in the field of deep space science,especially lunar-based exploration,is a scientific strategy that has been pursued in China and worldwide.Drilling and sampling are key to accurate exploration of the desirable characteristics of deep lunar resources.In this study,an in-situ condition preserved coring(ICP-Coring)and analysis system,which can be used to test drilling tools and develop effective sampling strategies,was designed.The key features of the system include:(1)capability to replicate the extreme temperature fluctuations of the lunar environment(-185 to 200℃)with intelligent temperature control;(2)ability to maintain a vacuum environment at a scale of 10^(-3) Pa,both under unloaded conditions within Ф580 mm×1000 mm test chamber,and under loaded conditions using Ф400 mm×800 mm lunar rock simulant;(3)application of axial pressures up to 4 MPa and confining pressures up to 3.5 MPa;(4)sample rotation at any angle with a maximum sampling length of 800 mm;and(5)multiple modes of rotary-percussive drilling,controlled by penetration speed and weight on bit(WOB).Experimental studies on the drilling characteristics in the lunar rock simulant-loaded state under different drill bit-percussive-vacuum environment configurations were conducted.The results show that the outgassing rate of the lunar soil simulant is greater than that of the lunar rock simulant and that a low-temperature environment contributes to a reduced vacuum of the lunar-based simulated environment.The rotary-percussive drilling method effectively shortens the sampling time.With increasing sampling depth,the temperature rise of the drilling tools tends to rapidly increase,followed by slow growth or steady fluctuations.The temperature rise energy accumulation of the drill bits under vacuum is more significant than that under atmospheric pressure,approximately 1.47 times higher.The real-time monitored drilling pressure,penetration speed and rotary torque during drilling serve as parameters for discriminating the drilling status.The results of this research can provide a scientific basis for returning samples from lunar rock in extreme lunar-based environments.
基金supported by the Teli Fellowship from Beijing Institute of Technology,the National Natural Science Foundation of China(Nos.52303366,22173109).
文摘In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterparts.The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications.In this context,the atomic substitution method has emerged as a favorable approach.It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely,crystal structures,and inherent properties of the resulting materials.In this review,we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional,one-dimensional and two-dimensional TMC materials.The effects of substituting elements,substitution ratios,and substitution positions on the structures and morphologies of resulting material are discussed.The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided,emphasizing the role of atomic substitution in achieving these advancements.Finally,challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.
基金supported by the National Natural Science Foundation of China(Grant No.62061014)Technological Innovation Projects in the Field of Artificial Intelligence in Liaoning province(Grant No.2023JH26/10300011)Basic Scientific Research Projects in Department of Education of Liaoning Province(Grant No.JYTZD2023021).
文摘Memristors are extensively used to estimate the external electromagnetic stimulation and synapses for neurons.In this paper,two distinct scenarios,i.e.,an ideal memristor serves as external electromagnetic stimulation and a locally active memristor serves as a synapse,are formulated to investigate the impact of a memristor on a two-dimensional Hindmarsh-Rose neuron model.Numerical simulations show that the neuronal models in different scenarios have multiple burst firing patterns.The introduction of the memristor makes the neuronal model exhibit complex dynamical behaviors.Finally,the simulation circuit and DSP hardware implementation results validate the physical mechanism,as well as the reliability of the biological neuron model.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10225417 and 61675009)the Natural Science Foundation of Beijing Municipality (Grant Nos. 4204091 and KZ201910005006)the China Postdoctoral Science Foundation (Grant No. 212423)。
文摘An all-fiber polarization maintaining high-power laser system operating at 1.7 μm based on the Ramaninduced soliton self-frequency shifting effect is demonstrated. The entirely fiberized system is built by erbiumdoped oscillator and two-stage amplifiers with polarization maintaining commercial silica fibers and devices, which can provide robust and stable soliton generation. High-power soliton laser with the average power of 0.28 W,the repetition rate of 42.7 MHz, and pulse duration of 515 fs is generated directly from the main amplifier.Our experiment provides a feasible method for high-power all-fiber polarization maintaining femtosecond laser generation working at 1.7 μm.
基金supported by grants from the National Heart,Lung,and Blood Institute(HL071981,HL034594,HL126024)the National Institute of Diabetes and Digestive and Kidney Diseases(DK115679,DK091718,DK100383,DK078616).
文摘Background Individuals with diabetes have a significantly higher risk of developing chronic kidney disease(CKD)and higher levels of social isolation and loneliness compared with those without diabetes.Recently,the American Heart Association highlighted the importance of considering social determinants of health(SDOH)in conjunction with traditional risk factors in patients with diabetes.Aims To investigate the associations of loneliness and social isolation with incident CKD risk in patients with diabetes in the UK Biobank.Methods A total of 18972 patients with diabetes were included in this prospective study.Loneliness and Social Isolation Scales were created based on self-reported factors.An adjusted Cox proportional hazard model was used to investigate the associations of loneliness and social isolation with CKD risk among patients with diabetes.The relative importance in predicting CKD was also calculated alongside traditional risk factors.Results During a median follow-up of 10.8 years,1127 incident CKD cases were reported.A higher loneliness scale,but not social isolation,was significantly associated with a 25%higher risk of CKD,independent of traditional risk factors,among patients with diabetes.Among the individual loneliness factors,the sense of feeling lonely emerged as the primary contributing factor to the elevated risk of CKD.Compared with individuals not experiencing feelings of loneliness,those who felt lonely exhibited a 22%increased likelihood of developing CKD.In addition,feeling lonely demonstrated greater relative importance of predicting CKD compared with traditional risk factors such as body mass index,smoking,physical activity and diet.Conclusions This study indicates the significant relationship between loneliness and CKD risk among patients with diabetes,highlighting the need to address SDOH in preventing CKD in this population.
基金financially supported by National Natural Science Foundation of China(U2013603,52004167)Program for Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08G315)China Postdoctoral Science Foundation(2021T140485)
文摘The exploration and development of oil and gas resources have shifted from shallow to deep and ultradeep.The difficulty of rock breaking has also increased,introducing new challenges to traditional rock-breaking technology.Hence,there is an urgent need to develop new rock-breaking technologies to improve the development efficiency of deep oil and gas resources.Therefore,this study focused on the new microwave rock-breaking technology and conducted experimental and numerical simulation research on typical deep,hard rock granite.The research results showed that granite in the microwave field exhibited high-temperature melting and fracture,and the highest temperature could reach 550°C.Under the irradiation of circulating microwaves,a minimum irradiation time threshold of 3 min was needed to cause irreversible damage to the rock.The numerical simulation results showed that the interaction of thermal stress and in situ stress would cause the inside of the rock stratum to separate into a disturbed deterioration area,disturbed unloading area and initial stress area.These results are expected to provide the necessary technical guidance and theoretical support for the research and development of high-efficiency rock-breaking drilling for deep hard rock.
基金supported by the National Natural Science Foundation of China(Nos.U2013603 and 52225403)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2019ZT08G315)the Shenzhen National Science Fund for Distinguished Young Scholars(No.RCJC20210706091948015).
文摘With the increasing scarcity of Earth’s resources and the development of space science and technology,the exploration, development, and utilization of deep space-specific material resources(minerals, water ice, volatile compounds, etc.) are not only important to supplement the resources and reserves on Earth but also provide a material foundation for establishing extraterrestrial research bases. To achieve large depth in-situ condition-preserved coring(ICP-Coring) in the extreme lunar environment, first, lunar rock simulant was selected(SZU-1), which has a material composition, element distribution, and physical and mechanical properties that are approximately equivalent to those of lunar mare basalt. Second, the influence of the lunar-based in-situ environment on the phase, microstructure, and thermal physical properties(specific heat capacity, thermal conductivity, thermal diffusivity, and thermal expansion coefficient)of SZU-1 was explored and compared with the measured lunar rock data. It was found that in an air atmosphere, low temperature has a more pronounced effect on the relative content of olivine than other temperatures, while in a vacuum atmosphere, the relative contents of olivine and anorthite are significantly affected only at temperatures of approximately-20 and 200 ℃. When the vacuum level is less than100 Pa, the contribution of air conduction can be almost neglected, whereas it becomes dominant above this threshold. Additionally, as the testing temperature increases, the surface of SZU-1 exhibits increased microcracking, fracture opening, and unevenness, while the specific heat capacity, thermal conductivity,and thermal expansion coefficient show nonlinear increases. Conversely, the thermal diffusivity exhibits a nonlinear decreasing trend. The relationship between thermal conductivity, thermal diffusivity, and temperature can be effectively described by an exponential function(R^(2)>0.98). The research results are consistent with previous studies on real lunar rocks. These research findings are expected to be applied in the development of the test and analysis systems of ICP-Coring in a lunar environment and the exploration of the mechanism of machine-rock interaction in the in-situ drilling and coring process.
基金supported by the Postgraduate Scientific Research Innovation Project of Hunan Province (No. CX20210922)
文摘A severe accident in a marine nuclear reactor leads to radionuclide leakage,which causes hidden dangers to workers and has adverse effects of environmental pollution.It is necessary to propose a novel approach to radionuclide diffusion in a confined environment after a severe accident in a marine nuclear reactor.Therefore,this study proposes a new method for the severe accident analysis program MELCOR coupled with computational fluid dynamics scSTREAM to study radioactive diffusion in severe accidents.The radionuclide release fraction and temperature calculated by MELCOR were combined with the scSTREAM calculations to study the radionuclide diffusion behavior and the phenomenon of radionuclide diffusion in different space environments of the reactor under the conditions of varying wind velocities of the ventilation system and diffusion speed.The results show that the wind velocity of the ventilation system is very small or zero,and the turbulent diffusion of radionuclides is not obvious and diffuses slowly in the form of condensation sedimentation and gravity settlement.When the wind speed of the ventilation system increases,the flow of radionuclides meets the wall and forms eddy currents,affecting the time variation of radionuclides diffusing into chamber 2.The wind velocity of the ventilation system and the diffusion speed has opposite effects on the time variation trend of radionuclide diffusion into the four chambers.
文摘Objective To investigate the image quality, radiation dose and diagnostic value of the low-tube-voltage high-pitch dual-source computed tomography(DSCT) with sinogram affirmed iterative reconstruction(SAFIRE) for non-enhanced abdominal and pelvic scans. Methods This institutional review board-approved prospective study included 64 patients who gave written informed consent for additional abdominal and pelvic scan with DSCT in the period from November to December 2012. The patients underwent standard non-enhanced CT scans(protocol 1) [tube voltage of 120 k Vp/pitch of 0.9/filtered back-projection(FBP) reconstruction] followed by high-pitch non-enhanced CT scans(protocol 2)(100 k Vp/3.0/SAFIRE). The total scan time, mean CT number, signal-to-noise ratio(SNR), image quality, lesion detectability and radiation dose were compared between the two protocols. Results The total scan time of protocol 2 was significantly shorter than that of protocol 1(1.4±0.1 seconds vs. 7.6±0.6 seconds, P<0.001). There was no significant difference between protocol 1 and protocol 2 in mean CT number of all organs(liver, 55.4±6.3 HU vs. 56.1±6.8 HU, P=0.214; pancreas, 43.6±5.9 HU vs. 43.7±5.8 HU, P=0.785; spleen, 47.9±3.9 HU vs. 49.4±4.3 HU, P=0.128; kidney, 32.2±2.3 HU vs. 33.1±2.3 HU, P=0.367; abdominal aorta, 44.8±5.6 HU vs. 45.0±5.5 HU, P=0.499; psoas muscle, 50.7±4.1 HU vs. 50.3±4.5 HU, P=0.279). SNR on images of protocol 2 was higher than that of protocol 1(liver, 5.0±1.2 vs. 4.5±1.1, P<0.001; pancreas, 4.0±1.0 vs. 3.6±0.8, P<0.001; spleen, 4.7±1.0 vs. 4.1±0.9, P<0.001; kidney, 3.1±0.6 vs. 2.8±0.6, P<0.001; abdominal aorta, 4.1±1.0 vs. 3.8±1.0, P<0.001; psoas muscle, 4.5±1.1 vs. 4.3±1.2, P=0.012). The overall image noise of protocol 2 was lower than that of protocol1(9.8±3.1 HU vs. 11.1±3.0 HU, P<0.001). Image quality of protocol 2 was good but lower than that of protocol 1(4.1±0.7 vs. 4.6±0.5, P<0.001). Protocol 2 perceived 229 of 234 lesions(97.9%) that were detected in protocol 1 in the abdomen and pelvis. Radiation dose of protocol 2 was lower than that of protocol 1(4.4±0.4 m Sv vs. 7.3±2.4 m Sv, P<0.001) and the mean dose reduction was 41.4%. Conclusion The high-pitch DSCT with SAFIRE can shorten scan time and reduce radiation dose while preserving image quality in non-enhanced abdominal and pelvic scans.
文摘Objective To measure volume and other parameters of normal adrenal glands in Chinese adults with 64-slice multidetector CT, to evaluate the relationship of volume result with age, sex and body size, and to explore the correlations between adrenal volume and other measurements. Methods This study was based on 125 acquired contrast-enhanced upper abdominal CT scans performed with a 64-slice CT. The final study group consisted of 81 patients (49 males, 32 females). Portal venous phase images were studied for the measurements. Both the reconstruction interval and thickness were 1.5 mm. Each adrenal gland was outlined manually with computer-assistant technology to calculate its volume. The maximal sectional area, length, width and thickness of each adrenal gland were also measured. Results The mean age of total population was 47.9±13.0 (range: 20-76) years. The left, right, and total adrenal gland volumes were 4.23±0.74 (range: 2.85-5.83) cm 3 , 4.26±0.86 (2.59-6.56) cm 3 , and 8.50±1.40 (5.80-11.39) cm 3 , respectively. These volumes increased with weight (r=0.381, 0.389, and 0.437 respectively, all P<0.001), height (r=0.386, P<0.001; r=0.297, P=0.007; r=0.384, P<0.001) and body surface area (r=0.406, 0.392, and 0.452, all P<0.001). There was no significant difference in left, right or total adrenal volume with regard to sex after applying General Linear Model procedure to reduce the impact of weight (F=1.304, 0.064, and 0.597, all P>0.05), nor did volume change significantly with age (r=-0.033, -0.014, and -0.026, all P>0.05). Nearly all descriptors of bilateral adrenal glands correlated with ipsilateral volume except thickness (r=-0.027, P=0.814) and width (r=0.166, P=0.138) in the left side. Among these parameters, length had a stronger correlation with volume than others in the both left (r=0.412, P<0.001) and right (r=0.516, P<0.001) adrenal glands. Conclusion Our study has defined the volume distribution and other parameters of normal adrenal glands in Chinese adults, which provide a baseline for future studies.
基金the financial supports by the Natural Science Foundation of China (NSFC21576158, 21476132, 21576159 and 21403130)Shandong Provincial Natural Science Foundation, China (No. 2015 ZRB01765)
文摘Porous carbon spheres are prepared by direct carbonization of potassium salt of resorcinol-formaldehyde resin spheres, and are investigated as COadsorbents. It is found that the prepared carbon materials still maintain the typical spherical shapes after the activation, and have highly developed ultra-microporosity with uniform pore size, indicating that almost the activation takes place in the interior of the polymer spheres. The narrow-distributed ultra-micropores are attributed to the "in-situ homogeneous activation"effect produced by the mono-dispersed potassium ions as a form of -OK groups in the bulk of polymer spheres. The CS-1 sample prepared under a KOH/resins weight ratio of 1 shows a very high COcapture capacity of 4.83 mmol/g and good CO/Nselectivity of7-45. We believe that the presence of a welldeveloped ultra-microporosity is responsible for excellent COsorption performance at room temperature and ambient pressure.
文摘Objective To retrospectively evaluate the effects of saline administration following contrast material injection, abdominal compression and two delay phase acquisition on image quality improvement of computed tomographic urography (CTU). Methods Medical records and informed consents of patients were obtained. In totally 122 patients (50 men, 72 women), two delay phase images with CTU were performed. Scans began simultaneously with a contrast bolus injection of 100 mL (300 mgI/mL) followed by a saline bolus injection of 100 mL at a rate of 5 mL/s. Two delay phase images were taken at 400 and 550 seconds for each patient. Examinations were taken by using abdominal compression or not. The distention and opacification of the urinary tract were evaluated by two interpreters together on transverse images and post-processing images. Effects of four techniques (saline administration and abdominal compression, saline administration only, compression only, and neither saline administration nor compression) and two delay phase acquisition on image quality improvement were analysed by using ANOVA and Chi-square test. Results Saline administration improved opacification (P<0.05) and increased overall image quality (P<0.01) of the intrarenal collecting system and proximal ureter. Abdominal compression (P<0.05) and delayed phase image acquisition of 550 seconds (P<0.01) all improved distention of the intrarenal collecting system and proximal ureter but did not improve opacification. No statistically significant effects on the distal ureter were found. However, there were more visualized distal ureteral segments with the longer imaging delay. Conclusion Saline administration, abdominal compression and longer imaging delays are all effective in improving image quality of 64-detector row CTU.
基金the National Science Foundation of China(Grant No.81501446).
文摘Objectives To investigate whether a longer time period of gadolinium ethoxybenzyl diethylenetriaminepen-taacetic add(Gd-EOB-DTPA)-enhanced T1 mapping scanning,as well as dynamic contrast-enhanced(DCE)and multiple hepatobiliary phase magnetic resonance imaging(MRI)have the potential to provide information about liver function in rats with liver fibrosis.Methods Forty rats were divided into the carbon tetrachloride-induced hepatic injury groups[carbon tetrachloride for four(n=14),eight(n=8),or twelve(n=8)weeks]and the control group(n=10).Gd-EOB-DTPA-enhanced MRI was performed including T1-mapping(delayed to 50 min),DCE,and multiple hepatobiliary phases.Indocyanine green retention rate at 15 min(ICG-R15)was determined.Parameters such as T1 reduction rate(△T1),elimination half-life of △T1(T_(△T1 1/2)),relative enhancement(RE),time to maximum RE(T_(max)),and perfusion parameters were calculated.Pearson correlation analysis was used for correlation analysis between ICG-R15 and each MRI indices.Results △T1 at 30,40,and 50 min showed significant positive correlations with ICG-R15(r=0.784,0.653,0.757,P=0.007,0.041,0.030).T_(△T1 1/2) showed a significant positive correlation with ICG-R15(r=0.685,P=0.029).showed a significant positive correlation with ICG-R15(r=0.532,P=0.019).Conclusions △T1 in the late hepatobiliary phase and T_(△T1 1/2) exhibited moderate correlations with liver function.The longer time period of Gd-EOB-DTPA-enhanced Tl mapping scanning,as well as DCE and multiple hepatobiliary phases,may be of some value for estimating liver function in rats with liver fibrosis.
文摘Numerous techniques have been developed to determine the bioavailability of minerals.Each method has specific detection objects with certain procedures to assure the results.This review focuses on a comprehensivecomparison of the applications,advantages,and critical control points of these techniques.The commonly used approaches for assessing mineral bioavailability can be divided into three categories-chemical methods,in vitro models and in vivo tests.Chemical methods are first developed,and mainly simulating the digestion environment to give a rough prediction of mineral bioavailability.In vitro models mainly used different cells to simulate the process and environment of food digestion to assess the availability of minerals.In vivo tests are employing complex models to observe the bioavailability of minerals after complicated digestive process in animal models or human volunteers.This review summarizes the critical points of establishment of these relevant models,compares the advantages and limitations among three categories.Although no single bioavailability method is ideal for all micronutrients,certain methods under proper operation can indeed be employed to minimize the differences between simulated results and reality for effective evaluation of the bioavailability of minerals.
