A novel intermediate fluid vaporization (IFV) technology for LNG re-gasification process with spiral-wound heat exchanging tubes is proposed. The new IFV project combines the advantage of running the shell and tube he...A novel intermediate fluid vaporization (IFV) technology for LNG re-gasification process with spiral-wound heat exchanging tubes is proposed. The new IFV project combines the advantage of running the shell and tube heat exchangers at high pressure with the advantage of compact space of heat exchangers. Thermal analysis on the two processes of forced convection and vaporization type heat transfer in the spiral wound tubes and vapor condensation /re-boiling type of heat transfer via intermediate fluid in shell side shows the feasibility of this promising technology.展开更多
Shell-and-tube vaporizers are the most commonly used and dominated types of vaporizers in liquefied natural gas （LNG） realm. Due to efficient performance, shell-side flow in this type of vaporizers has received cons...Shell-and-tube vaporizers are the most commonly used and dominated types of vaporizers in liquefied natural gas （LNG） realm. Due to efficient performance, shell-side flow in this type of vaporizers has received considerable attention and has been investigated extensively. However, the detailed flow structure in the shell needs to be determined for reliable and effective design. Therefore, the objective of this study was to clarify the flow structure in shell by particle image velocimetry （PIV）. Experiments were conducted using two types of model; 15% baffle cut having inlet and outlet positions !n the direction of 90° to the cut and 30% baffle cut having inlet and outlet positions in the direction of 180° to the cut. Each test section is 169 mm in inner diameter and 344.6 mm in length. The flow features were characterized in different baffle cuts with regards to the velocity vector field and velocity distribution. The results show that the flow characteristics of 15% baffle cut type vaporizer are comparable to those of 30% baffle cut type vaporizer.展开更多
In order to optimize the design of the submerged combustion vaporizer(SCV), an experimental apparatus was set up to investigate the heat transfer character outside the tube bundle in SCV. Several experiments were cond...In order to optimize the design of the submerged combustion vaporizer(SCV), an experimental apparatus was set up to investigate the heat transfer character outside the tube bundle in SCV. Several experiments were conducted using water and CO_2 as the heat transfer media in the tubes, respectively. The results indicated that hot air flux, the initial liquid level height and the tube pitch ratio had great influence on the heat transfer coefficient outside the tube bundle(ho). Finally, the air flux associated factor β and height associated factor γ were introduced to propose a new hocorrelation. After verified by experiments using cold water, high pressure CO_2 and liquid N_2 as heat transfer media, respectively, it was found that the biggest deviation between the predicted and the experimental values was less than 25%.展开更多
Thermal conductivity of frost is not only related to density, but also affected by its microstructure and environmental conditions, and it will continuously change with the formation and growth of frost. Images of fro...Thermal conductivity of frost is not only related to density, but also affected by its microstructure and environmental conditions, and it will continuously change with the formation and growth of frost. Images of frost formation and growth on the cryogenic surface in various shapes at different stages were obtained by experimental measurements, and a numerical simulation of frost formation and growth was carried out based on Diffusion Limited Aggregation (DLA) model of fractal theory in this paper. Based on the frost structure obtained by experiment, the fractal dimension of pore area distribution and porosity of frost layer on the cryogenic finned-tube?vaporizer were calculated by using fractal method, and combined with heat conduction model of frost layer obtained by thermal resistance method, the thermal conductivity of frost on the cryogenic surface was calculated. The result shows that the thermal conductivity calculated by the fractal model coincides with the range of the experimental data. Additionally, comparison with other heat conduction models indicated that it is feasible to introduce the fractal dimension of pore area distribution into heat conduction model to deduce the thermal conductivity of frost.展开更多
The intermediate fluid vaporizer(IFV)is a typical vaporizer of liquefied natural gas(LNG),which in general consists of three shell-and-tube heat exchangers(an evaporator,a condenser,and a thermolator).LNG is heated by...The intermediate fluid vaporizer(IFV)is a typical vaporizer of liquefied natural gas(LNG),which in general consists of three shell-and-tube heat exchangers(an evaporator,a condenser,and a thermolator).LNG is heated by seawater and the intermediate fluid in these heat exchangers.A one-dimensional heat transfer model for IFV is established in this paper in order to investigate the influences of structure and operation parameters on the heat transfer performance.In the rated condition,it is suggested to reduce tube diameters appropriately to get a large total heat transfer coefficient and increase the tube number to ensure the sufficient heat transfer area.According to simulation results,although the IFV capacity is much larger than the simplified-IFV(SIFV)capacity,the mode of SIFV could be recommended in some low-load cases as well.In some cases at high loads exceeding the capacity of a single IFV,it is better to add an AAV or an SCV operating to the IFV than just to increase the mass flow rate of seawater in the IFV in LNG receiving terminals.展开更多
The intermediate fluid vaporizer (IFV), different from other liquefied natural gas (LNG) vaporizers, has many advantages and has shown a great potential for future applications. In this present paper, studies of IFV a...The intermediate fluid vaporizer (IFV), different from other liquefied natural gas (LNG) vaporizers, has many advantages and has shown a great potential for future applications. In this present paper, studies of IFV and its heat transfer characteristics in the LNG vaporization unit E2 are systematically reviewed. The research methods involved include theoretical analysis, experimental investigation, numerical simulation, and process simulation. First, relevant studies on the overall calculation and system design of IFV are summarized, including the structural innovation design, the thermal calculation model, and the selection of different intermediate fluids. Moreover, studies on the fluid flow and heat transfer behaviors of the supercritical LNG inside the tubes and the condensation heat transfer of the intermediate fluid outside the tubes are summarized. In the thermal calculations of the IFV, the selections of the existing heat transfer correlations about the intermediate fluids are inconsistent in different studies, and there lacks the accuracy evaluation of those correlations or comparison with experimental data. Furthermore, corresponding experiments or numerical simulations on the cryogenic condensation heat transfer outside the tubes in the IFV need to be further improved, compared to those in the refrigeration and air-conditioning temperature range. Therefore, suggestions for further studies of IFV are provided as well.展开更多
Magnesium(Mg),as one of the most abundant elements in earth's crust,is the lightest structural metal with extensive applications across various industries.However,the performance of Mg-based products is highly dep...Magnesium(Mg),as one of the most abundant elements in earth's crust,is the lightest structural metal with extensive applications across various industries.However,the performance of Mg-based products is highly dependent on their impurity levels,and the lack of high-purity Mg,along with efficient purification method,has posed significant challenge to its widespread industrial adoption.This study investigates the impurity behavior in Mg ingots during the vacuum gasification purification process.Through the analysis of binary phase diagrams,iron(Fe)-based foam material was selected for the filtration and purification of Mg vapor in a vacuum tube furnace.A novel approach combining vacuum gasification,vapor purification,and directional condensation is proposed.The effect of filter pore sizes and filtration temperatures on the efficacy of impurity removal was evaluated.Experimental results demonstrate that Fe-based foam with a pore size of 60 ppi,at a filtration temperature of 773 K,effectively removes impurities such as calcium(Ca),potassium(K),sodium(Na),manganese(Mn),silicon(Si),aluminum(Al),and various oxides,sulfides,and chlorides from the vapor phase.Consequently,high-purity Mg with a purity level exceeding 5N3 was obtained in the condensation zone.展开更多
Cu suffers from oxidation and corrosion during application due to its active chemical properties.Graphene⁃modified Cu can significantly improve its stability during application.However,copper is easily sintered at hig...Cu suffers from oxidation and corrosion during application due to its active chemical properties.Graphene⁃modified Cu can significantly improve its stability during application.However,copper is easily sintered at high temperatures,so that graphene cannot be grown inside.We demonstrate two kinds of spacers,graphite and SiO_(2),which are effective in preventing the sintering of copper and are used to assist in the growth of graphene.In the Cu⁃C system,the nucleation of graphene is scarce,and it tends to nucleate and grow on the concave surface of copper first,and then grow epitaxially to the convex surface of copper.Eventually,the obtained graphene is relatively thick.In the Cu⁃SiO_(2) system,due to the oxygen released by SiO_(2) at high temperatures,the surface of copper becomes rough.This leads to an increase in the number of graphene nucleation sites without preferred orientation,and relatively thin graphene is obtained.Two different growth mechanisms have been established for spacerseffects on graphene growth.It provides insights for graphene engineering for further applications.展开更多
Background:The surgical management of patients with benign prostatic hyperplasia(BPH)has considerably evolved through recent years.Nonetheless,benefits and harms of several laser procedures are still to be determined....Background:The surgical management of patients with benign prostatic hyperplasia(BPH)has considerably evolved through recent years.Nonetheless,benefits and harms of several laser procedures are still to be determined.The study aimed to report perioperative and early functional results of patients treated with anatomical photo vaporization of the prostate(aPVP).Methods:Data from consecutive patients treated with aPVP by using a 180-W XPS GreenLight laser were prospectively collected in a single tertiary center between 2020 and 2023.The surgical procedure was divided into a modular step-by-step fashion.Patients were asked to complete self-administered questionnaires at baseline and during follow-up visits.Results:Overall,176 consecutive patients were enrolled.Median age was 65[interquartile range(IQR)63–72]years.The baseline median prostate volume was 61.2(IQR 52.5–71.0)mL,and the median max flow rate(Qmax)was 9.3(IQR 7.8–11.5)mL/s.Median preoperative International Prostate Symptom Score(IPSS)was 25(IQR 22–29).Overall,the median operative time was 42(IQR 31–47)minutes with a median energy/mL of tissue delivered of 2447 kJ/mL.At 3 month-evaluation,significant improvements were observed,with a median Qmax of 28(IQR:24–32)mL/s and a median IPSS reduction of 15(IQR:11–18)points.A strong inverse correlation was identified between energy delivery during initial procedural steps and the severity of postoperative storage symptoms(all p<0.05),underscoring the importance of precise energy modulation.Multivariate analysis identified increased prostate volume(odds ratio[OR]:1.02;95%confidence interval[CI]1.01–1.11;p=0.001)and higher prostate width-to-length ratio(OR:1.28;95%CI 1.04–1.78;p=0.03)as independent predictors of increased energy requirements.Conclusions:aPVP with 180-W XPS GreenLight laser is a safe and effective technique showing worthy early functional results.The limitation of the energy delivered in some key phases of the procedure may be associated with a significant reduction in postoperative irritative symptoms.The shape and dimensions of the prostate also play a critical role in determining the total energy required for complete adenoma removal.展开更多
The phase transition among different solid forms of active pharmaceutical ingredients can significantly influence their physicochemical properties,potentially leading to clinical safety risks.However,phase transition ...The phase transition among different solid forms of active pharmaceutical ingredients can significantly influence their physicochemical properties,potentially leading to clinical safety risks.However,phase transition mechanisms remain under explored,especially in multi-component drugs.Here we report a novel ciprofloxacin-diclofenac salt system and investigate phase transitions among its anhydrate,dihydrate,and methanol solvate forms.The study focused on the influence of water activity and solvent vapor conditions,elucidating the role of vip molecules in driving these transitions.These findings offer new insights into polymorphic phase transitions,advancing our understanding of stability and performance in pharmaceutical formulations.展开更多
Two-dimensional(2D)MoO_(2),a binary nonlayered material,has been extensively studied for potential applications in catalysis and electronics.However,the preparation of 2D MoO_(2) remains challenging.Herein,we report t...Two-dimensional(2D)MoO_(2),a binary nonlayered material,has been extensively studied for potential applications in catalysis and electronics.However,the preparation of 2D MoO_(2) remains challenging.Herein,we report the growth of 2D MoO_(2) flakes with rhombic morphology on the sapphire substrate via a chemical vapor deposition(CVD)method.Atomic force microscopy shows the CVDgrown MoO_(2) flakes with thin thickness.The CVD-obtained MoO_(2) with a stoichiometric ratio of 1:2 is verified using energy-dispersive X-ray spectroscopy.Scanning transmission electron microscopy(STEM)characterization reveals the high-quality,single-crystal nature of the CVDderived 2D MoO_(2) flakes.展开更多
Growth of high-quality Nb_(3)Sn thin films for superconducting radiofrequency(SRF)applications using the vapor diffusion method requires a uniform distribution of tin nuclei on the niobium(Nb)surface.This study examin...Growth of high-quality Nb_(3)Sn thin films for superconducting radiofrequency(SRF)applications using the vapor diffusion method requires a uniform distribution of tin nuclei on the niobium(Nb)surface.This study examines the mechanism underlying the observed non-uniform distribution of tin nuclei with tin chloride SnCl_(2).Electron backscatter diffraction(EBSD)analysis was used to examine the correlation between the nucleation behavior and orientation of niobium grains in the substrate.The findings of the density functional theory(DFT)simulation are in good agreement with the experimental results,showing that the non-uniform distribution of tin nuclei is the result of the adsorption energy of SnCl_(2)molecules by varied niobium grain orientations.Further analysis indicated that the surface roughness and grain size of niobium also played significant roles in the nucleation behavior.This study provides valuable insights into enhancing the surface pretreatment of niobium substrates during the growth of Nb_(3)Sn thin films using the vapor diffusion method.展开更多
In the context of convection-heating-based in situ oil shale retorting,fractures serve as primary pathways for fluid migration and product extraction.This study investigates the permeability and microstructural evolut...In the context of convection-heating-based in situ oil shale retorting,fractures serve as primary pathways for fluid migration and product extraction.This study investigates the permeability and microstructural evolution of oil shale during water vapor injection in single-fracture and no-fracture scenarios.Three types of oil shale are investigated:intact oil shale,oil shale with a single straight crack,and oil shale with a single hydraulic crack.With increasing water vapor temperature,the permeabilities of the intact oil shale and oil shale with a fractured crack exhibit a trend of initial increase,followed by a decrease,and then a subsequent increase.However,the permeability of oil shale with a single straight crack consistently increases and exceeds that of oil shale with a fractured crack.The temperaturedependent permeability changes in fractured oil shale-a slight decrease in fracture cracks and a gradual increase in straight cracks-mainly occur in the range of 300℃-350℃.The permeability of oil shale with a straight crack is approximately three times that of oil shale with a fractured crack.This is attributed to the retention of viscous asphaltene and the frictional resistance caused by the rough fracture structure.For the oil shale with a single crack,the crack permeability has a dominant influence on the overall permeability of the rock.The contribution of the permeability of the straight crack exceeds 94.6%,while that of the permeability of the fractured crack is greater than 86.1%.The disparity in the contribution of these two crack structures is evident at 350℃-550℃.展开更多
Global deforestation has been recognized as an important factor influencing climate change over the past century.However, uncertainties remain regarding its biophysical impacts on temperature across China. Utilizing m...Global deforestation has been recognized as an important factor influencing climate change over the past century.However, uncertainties remain regarding its biophysical impacts on temperature across China. Utilizing monthly data from eight global climate models of the Land Use Model Intercomparison Project, a multimodel comparison was conducted to quantitatively analyze the biophysical impacts of global deforestation on near-surface air temperature in China, using a surface energy balance decomposition method. Results show a 38%(29% to 45%) reduction in forest cover in China(ensemble mean and range across eight models) relative to pre-industrial levels, and an annual cooling of 0.6 K(0.05 to1.4 K) accompanied by global deforestation. Notably, surface albedo causes a cooling effect of 0.6 K(0.2 to 2.0 K), while surface latent and sensible heat fluxes partially offset this cooling by 0.2 K(-0.2 to 0.5 K) and 0.2 K(-0.04 to 0.6 K),respectively. These effects are more pronounced in winter and spring in deforested regions. Furthermore, the separation of atmospheric feedbacks under clear-sky and cloudy conditions show that the cloud radiative effect only accounts for 0.1 K(-0.1 to 0.4 K), while the clear-sky surface downward radiation is a significant cooling factor, contributing up to-0.5 K(-1.2 to 0.004 K), particularly in summer. However, the consistency of these models in simulating the impact of surface latent heat flux and albedo on surface temperature in China in response to deforestation is somewhat poor, highlighting the need to improve these related processes.展开更多
High atmospheric vapor pressure deficit(VPD)reduces the calcium(Ca)distribution in tomato(Solanum lycopersicum L.)fruits,severely reducing fruit mass.Reducing the VPD or increasing Ca fertilizer is an important measur...High atmospheric vapor pressure deficit(VPD)reduces the calcium(Ca)distribution in tomato(Solanum lycopersicum L.)fruits,severely reducing fruit mass.Reducing the VPD or increasing Ca fertilizer is an important measure to improve Ca distribution in fruits.However,the mechanism through which VPD and Ca regulate fruit Ca distribution remains unclear.This study investigated the effects of high and low VPD and Ca levels on Ca distribution and fruit mass based on carbon fixation,water transport dynamics,and pectin and Ca content and identified key differential genes and metabolites through transcriptome and metabolome analyses.The results showed that both reducing VPD under low Ca and increasing Ca under high VPD increased water and Ca transport to fruits.The increased Ca combined with pectin to form Ca pectinate,which effectively stabilized the cell wall and enhanced the fruit mass.Reduced VPD under low Ca increased the distribution of Ca to fruits but decreased the distribution of Ca to leaves.Lower Ca distribution in leaves increased their absorption of other nutrients,such as potassium,magnesium,copper,and zinc,which increased the stomatal size and density,thereby improving plant carbon absorption and assimilation efficiency.However,transcriptomic and metabolomic data indicated that carbohydrates,as important regulatory factors under drought stress,increased significantly under high VPD,thereby reducing the fruit water potential while improving fruit water and Ca absorption.Therefore,the carbon assimilation efficiency,water transport capacity,and differential genes and metabolites regulated Ca distribution.This work provides a theoretical basis for environmental and fertilizer management in greenhouse tomato production.展开更多
Rapidly growing population,escalating urbanization,and industrialization are causing the depletion of non-renewable resources and air pollution,a silent pandemic responsible for billions of global mortalities.Sensors ...Rapidly growing population,escalating urbanization,and industrialization are causing the depletion of non-renewable resources and air pollution,a silent pandemic responsible for billions of global mortalities.Sensors are crucial vectors for monitoring the emission of various gases/volatile organic compoundsbased pollutants from various anthropogenic sources.Borophene-based nanomaterials(BNMs)are the latest two-dimensional flatlands to this emergent next-generation sensors family with exceptional and tunable physicochemical attributes characterized by high anisotropy,thermal/mechanical resilience,tunable bandgaps,light-weight,high charge carrier mobility,and excellent adsorption efficacies.However,the practical implementation and scalability of BNMs grapple with challenges,including instability,substrateto-device transfer complications,and optimization intricacies.This comprehensive review delves into state-of-the-art BNM sensor fabrication techniques,intertwining theoretical insights derived from density functional theory and molecular dynamics with practical evaluations and on-site applications.Besides,the fundamental challenges associated with engineering BNM sensors and their alternate solutions by employing various strategies,including surface termination,functionalization,hydrogenation,hybridization,architecting composites,and green chemistry,are detailed.This review offers a roadmap from lab to market,bridging theoretical insights with practical implementation and expediting the advanced BNM sensors with wearable,remotely accessible,point-of-care,scavenging,self-powered,biocompatible,and intelligent modules for pollution management.展开更多
Graphene meshes(GMs)have attracted considerable attention as advanced materials for high-performance gas sensing due to their high-density active edge sites and excellent electronic properties.However,the contaminatio...Graphene meshes(GMs)have attracted considerable attention as advanced materials for high-performance gas sensing due to their high-density active edge sites and excellent electronic properties.However,the contamination-free preparation of GMs remains a challenge.Herein,we present a dewdrop-templated chemical vapor deposition approach to directly grow clean and intact graphene micromeshes(GMM)on SiO_(2)/Si substrates.The self-assembled micrometer-sized dewdrops from controlled water vapor condensation serve as a residue-free template for directing the growth of GMM with tunable hole sizes from submicrons to tens of microns.Density functional theory(DFT)calculations reveal that carbon species preferentially adsorb on pristine SiO_(2) regions to form a mesh structure.Contamination-free GMM gas sensors were fabricated using a simple transfer-free process,demonstrating a record-high sensitivity of 7.25%·ppm−1 and an ultra-low detection limit of 1.18 ppb for NO_(2) at room temperature.Complementary DFT studies elucidate that NO_(2) molecules adsorb more strongly on the edges of GMM,leading to a high response of the sensor.This work offers profound insights into dewdrop-templated graphene growth mechanisms and establishes a simple yet effective approach for fabricating high-performance transfer-free GMM sensors,thus paving the way for their practical applications in environmental monitoring and industrial safety fields.展开更多
基金supported by grants from the Fundamental Research Funds for the Central Universities(DUT12JN01)the National Natural Science Foundation of China(51106017)
文摘A novel intermediate fluid vaporization (IFV) technology for LNG re-gasification process with spiral-wound heat exchanging tubes is proposed. The new IFV project combines the advantage of running the shell and tube heat exchangers at high pressure with the advantage of compact space of heat exchangers. Thermal analysis on the two processes of forced convection and vaporization type heat transfer in the spiral wound tubes and vapor condensation /re-boiling type of heat transfer via intermediate fluid in shell side shows the feasibility of this promising technology.
基金supported by the National Research Foundation of Korea Grant funded by the Korean Government (NRF-2010-013-D00007)2010 Research Professor Fund of Gyeongsang National University,Korea
文摘Shell-and-tube vaporizers are the most commonly used and dominated types of vaporizers in liquefied natural gas （LNG） realm. Due to efficient performance, shell-side flow in this type of vaporizers has received considerable attention and has been investigated extensively. However, the detailed flow structure in the shell needs to be determined for reliable and effective design. Therefore, the objective of this study was to clarify the flow structure in shell by particle image velocimetry （PIV）. Experiments were conducted using two types of model; 15% baffle cut having inlet and outlet positions !n the direction of 90° to the cut and 30% baffle cut having inlet and outlet positions in the direction of 180° to the cut. Each test section is 169 mm in inner diameter and 344.6 mm in length. The flow features were characterized in different baffle cuts with regards to the velocity vector field and velocity distribution. The results show that the flow characteristics of 15% baffle cut type vaporizer are comparable to those of 30% baffle cut type vaporizer.
文摘In order to optimize the design of the submerged combustion vaporizer(SCV), an experimental apparatus was set up to investigate the heat transfer character outside the tube bundle in SCV. Several experiments were conducted using water and CO_2 as the heat transfer media in the tubes, respectively. The results indicated that hot air flux, the initial liquid level height and the tube pitch ratio had great influence on the heat transfer coefficient outside the tube bundle(ho). Finally, the air flux associated factor β and height associated factor γ were introduced to propose a new hocorrelation. After verified by experiments using cold water, high pressure CO_2 and liquid N_2 as heat transfer media, respectively, it was found that the biggest deviation between the predicted and the experimental values was less than 25%.
文摘Thermal conductivity of frost is not only related to density, but also affected by its microstructure and environmental conditions, and it will continuously change with the formation and growth of frost. Images of frost formation and growth on the cryogenic surface in various shapes at different stages were obtained by experimental measurements, and a numerical simulation of frost formation and growth was carried out based on Diffusion Limited Aggregation (DLA) model of fractal theory in this paper. Based on the frost structure obtained by experiment, the fractal dimension of pore area distribution and porosity of frost layer on the cryogenic finned-tube?vaporizer were calculated by using fractal method, and combined with heat conduction model of frost layer obtained by thermal resistance method, the thermal conductivity of frost on the cryogenic surface was calculated. The result shows that the thermal conductivity calculated by the fractal model coincides with the range of the experimental data. Additionally, comparison with other heat conduction models indicated that it is feasible to introduce the fractal dimension of pore area distribution into heat conduction model to deduce the thermal conductivity of frost.
文摘The intermediate fluid vaporizer(IFV)is a typical vaporizer of liquefied natural gas(LNG),which in general consists of three shell-and-tube heat exchangers(an evaporator,a condenser,and a thermolator).LNG is heated by seawater and the intermediate fluid in these heat exchangers.A one-dimensional heat transfer model for IFV is established in this paper in order to investigate the influences of structure and operation parameters on the heat transfer performance.In the rated condition,it is suggested to reduce tube diameters appropriately to get a large total heat transfer coefficient and increase the tube number to ensure the sufficient heat transfer area.According to simulation results,although the IFV capacity is much larger than the simplified-IFV(SIFV)capacity,the mode of SIFV could be recommended in some low-load cases as well.In some cases at high loads exceeding the capacity of a single IFV,it is better to add an AAV or an SCV operating to the IFV than just to increase the mass flow rate of seawater in the IFV in LNG receiving terminals.
文摘The intermediate fluid vaporizer (IFV), different from other liquefied natural gas (LNG) vaporizers, has many advantages and has shown a great potential for future applications. In this present paper, studies of IFV and its heat transfer characteristics in the LNG vaporization unit E2 are systematically reviewed. The research methods involved include theoretical analysis, experimental investigation, numerical simulation, and process simulation. First, relevant studies on the overall calculation and system design of IFV are summarized, including the structural innovation design, the thermal calculation model, and the selection of different intermediate fluids. Moreover, studies on the fluid flow and heat transfer behaviors of the supercritical LNG inside the tubes and the condensation heat transfer of the intermediate fluid outside the tubes are summarized. In the thermal calculations of the IFV, the selections of the existing heat transfer correlations about the intermediate fluids are inconsistent in different studies, and there lacks the accuracy evaluation of those correlations or comparison with experimental data. Furthermore, corresponding experiments or numerical simulations on the cryogenic condensation heat transfer outside the tubes in the IFV need to be further improved, compared to those in the refrigeration and air-conditioning temperature range. Therefore, suggestions for further studies of IFV are provided as well.
基金supported by the Yunnan Province Nonferrous Metal Vacuum Metallurgy Top Team[No.202305AS350012]。
文摘Magnesium(Mg),as one of the most abundant elements in earth's crust,is the lightest structural metal with extensive applications across various industries.However,the performance of Mg-based products is highly dependent on their impurity levels,and the lack of high-purity Mg,along with efficient purification method,has posed significant challenge to its widespread industrial adoption.This study investigates the impurity behavior in Mg ingots during the vacuum gasification purification process.Through the analysis of binary phase diagrams,iron(Fe)-based foam material was selected for the filtration and purification of Mg vapor in a vacuum tube furnace.A novel approach combining vacuum gasification,vapor purification,and directional condensation is proposed.The effect of filter pore sizes and filtration temperatures on the efficacy of impurity removal was evaluated.Experimental results demonstrate that Fe-based foam with a pore size of 60 ppi,at a filtration temperature of 773 K,effectively removes impurities such as calcium(Ca),potassium(K),sodium(Na),manganese(Mn),silicon(Si),aluminum(Al),and various oxides,sulfides,and chlorides from the vapor phase.Consequently,high-purity Mg with a purity level exceeding 5N3 was obtained in the condensation zone.
文摘Cu suffers from oxidation and corrosion during application due to its active chemical properties.Graphene⁃modified Cu can significantly improve its stability during application.However,copper is easily sintered at high temperatures,so that graphene cannot be grown inside.We demonstrate two kinds of spacers,graphite and SiO_(2),which are effective in preventing the sintering of copper and are used to assist in the growth of graphene.In the Cu⁃C system,the nucleation of graphene is scarce,and it tends to nucleate and grow on the concave surface of copper first,and then grow epitaxially to the convex surface of copper.Eventually,the obtained graphene is relatively thick.In the Cu⁃SiO_(2) system,due to the oxygen released by SiO_(2) at high temperatures,the surface of copper becomes rough.This leads to an increase in the number of graphene nucleation sites without preferred orientation,and relatively thin graphene is obtained.Two different growth mechanisms have been established for spacerseffects on graphene growth.It provides insights for graphene engineering for further applications.
文摘Background:The surgical management of patients with benign prostatic hyperplasia(BPH)has considerably evolved through recent years.Nonetheless,benefits and harms of several laser procedures are still to be determined.The study aimed to report perioperative and early functional results of patients treated with anatomical photo vaporization of the prostate(aPVP).Methods:Data from consecutive patients treated with aPVP by using a 180-W XPS GreenLight laser were prospectively collected in a single tertiary center between 2020 and 2023.The surgical procedure was divided into a modular step-by-step fashion.Patients were asked to complete self-administered questionnaires at baseline and during follow-up visits.Results:Overall,176 consecutive patients were enrolled.Median age was 65[interquartile range(IQR)63–72]years.The baseline median prostate volume was 61.2(IQR 52.5–71.0)mL,and the median max flow rate(Qmax)was 9.3(IQR 7.8–11.5)mL/s.Median preoperative International Prostate Symptom Score(IPSS)was 25(IQR 22–29).Overall,the median operative time was 42(IQR 31–47)minutes with a median energy/mL of tissue delivered of 2447 kJ/mL.At 3 month-evaluation,significant improvements were observed,with a median Qmax of 28(IQR:24–32)mL/s and a median IPSS reduction of 15(IQR:11–18)points.A strong inverse correlation was identified between energy delivery during initial procedural steps and the severity of postoperative storage symptoms(all p<0.05),underscoring the importance of precise energy modulation.Multivariate analysis identified increased prostate volume(odds ratio[OR]:1.02;95%confidence interval[CI]1.01–1.11;p=0.001)and higher prostate width-to-length ratio(OR:1.28;95%CI 1.04–1.78;p=0.03)as independent predictors of increased energy requirements.Conclusions:aPVP with 180-W XPS GreenLight laser is a safe and effective technique showing worthy early functional results.The limitation of the energy delivered in some key phases of the procedure may be associated with a significant reduction in postoperative irritative symptoms.The shape and dimensions of the prostate also play a critical role in determining the total energy required for complete adenoma removal.
基金supported by the Young Scientists Promotion Fund of Natural Science Foundation of Guangdong Province(No.2023A1515030128)Natural Science Foundation of Guangdong Province(No.2024A1515011590)+1 种基金National Natural Science Foundation of China(No.81703438)CAMS Innovation Fund for Medical Sciences(No.2022-I2M-1-015).
文摘The phase transition among different solid forms of active pharmaceutical ingredients can significantly influence their physicochemical properties,potentially leading to clinical safety risks.However,phase transition mechanisms remain under explored,especially in multi-component drugs.Here we report a novel ciprofloxacin-diclofenac salt system and investigate phase transitions among its anhydrate,dihydrate,and methanol solvate forms.The study focused on the influence of water activity and solvent vapor conditions,elucidating the role of vip molecules in driving these transitions.These findings offer new insights into polymorphic phase transitions,advancing our understanding of stability and performance in pharmaceutical formulations.
基金supported by the Science and Technology Plan Project of Tangshan Science and Technology Bureau(No.22130217H)the Natural Science Foundation-Steel and Iron Foundation of Hebei Province(No.E2022209114)the Open Research Fund from Guangxi Key Laboratory of Information Materials,Guilin University of Electronic Technology(No.221004-K).
文摘Two-dimensional(2D)MoO_(2),a binary nonlayered material,has been extensively studied for potential applications in catalysis and electronics.However,the preparation of 2D MoO_(2) remains challenging.Herein,we report the growth of 2D MoO_(2) flakes with rhombic morphology on the sapphire substrate via a chemical vapor deposition(CVD)method.Atomic force microscopy shows the CVDgrown MoO_(2) flakes with thin thickness.The CVD-obtained MoO_(2) with a stoichiometric ratio of 1:2 is verified using energy-dispersive X-ray spectroscopy.Scanning transmission electron microscopy(STEM)characterization reveals the high-quality,single-crystal nature of the CVDderived 2D MoO_(2) flakes.
基金supported by the National Natural Science Foundation of China(No.12175283)Youth Innovation Promotion Association of Chinese Academy of Sciences(2020410)Advanced Energy Science and Technology Guangdong Laboratory(HND20TDSPCD,HND22PTDZD).
文摘Growth of high-quality Nb_(3)Sn thin films for superconducting radiofrequency(SRF)applications using the vapor diffusion method requires a uniform distribution of tin nuclei on the niobium(Nb)surface.This study examines the mechanism underlying the observed non-uniform distribution of tin nuclei with tin chloride SnCl_(2).Electron backscatter diffraction(EBSD)analysis was used to examine the correlation between the nucleation behavior and orientation of niobium grains in the substrate.The findings of the density functional theory(DFT)simulation are in good agreement with the experimental results,showing that the non-uniform distribution of tin nuclei is the result of the adsorption energy of SnCl_(2)molecules by varied niobium grain orientations.Further analysis indicated that the surface roughness and grain size of niobium also played significant roles in the nucleation behavior.This study provides valuable insights into enhancing the surface pretreatment of niobium substrates during the growth of Nb_(3)Sn thin films using the vapor diffusion method.
基金funded by the Open Research Fund of the State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources,China University of Mining and Technology(Grant No.SKLCRSM23KF018)the National Natural Science Foundation of China(Grant No.52104144)the National Key R&D Program of China(Grant No.2019YFA0705501).
文摘In the context of convection-heating-based in situ oil shale retorting,fractures serve as primary pathways for fluid migration and product extraction.This study investigates the permeability and microstructural evolution of oil shale during water vapor injection in single-fracture and no-fracture scenarios.Three types of oil shale are investigated:intact oil shale,oil shale with a single straight crack,and oil shale with a single hydraulic crack.With increasing water vapor temperature,the permeabilities of the intact oil shale and oil shale with a fractured crack exhibit a trend of initial increase,followed by a decrease,and then a subsequent increase.However,the permeability of oil shale with a single straight crack consistently increases and exceeds that of oil shale with a fractured crack.The temperaturedependent permeability changes in fractured oil shale-a slight decrease in fracture cracks and a gradual increase in straight cracks-mainly occur in the range of 300℃-350℃.The permeability of oil shale with a straight crack is approximately three times that of oil shale with a fractured crack.This is attributed to the retention of viscous asphaltene and the frictional resistance caused by the rough fracture structure.For the oil shale with a single crack,the crack permeability has a dominant influence on the overall permeability of the rock.The contribution of the permeability of the straight crack exceeds 94.6%,while that of the permeability of the fractured crack is greater than 86.1%.The disparity in the contribution of these two crack structures is evident at 350℃-550℃.
基金supported by the National Natural Science Foundation of China (Grant No.42305041)the Natural Science Foundation of Hubei Province of China (Grant No.2020CFB331)supported by the National Key Scientific and Technological Infrastructure project “Earth System Numerical Simulation Facility” (Earth Lab)。
文摘Global deforestation has been recognized as an important factor influencing climate change over the past century.However, uncertainties remain regarding its biophysical impacts on temperature across China. Utilizing monthly data from eight global climate models of the Land Use Model Intercomparison Project, a multimodel comparison was conducted to quantitatively analyze the biophysical impacts of global deforestation on near-surface air temperature in China, using a surface energy balance decomposition method. Results show a 38%(29% to 45%) reduction in forest cover in China(ensemble mean and range across eight models) relative to pre-industrial levels, and an annual cooling of 0.6 K(0.05 to1.4 K) accompanied by global deforestation. Notably, surface albedo causes a cooling effect of 0.6 K(0.2 to 2.0 K), while surface latent and sensible heat fluxes partially offset this cooling by 0.2 K(-0.2 to 0.5 K) and 0.2 K(-0.04 to 0.6 K),respectively. These effects are more pronounced in winter and spring in deforested regions. Furthermore, the separation of atmospheric feedbacks under clear-sky and cloudy conditions show that the cloud radiative effect only accounts for 0.1 K(-0.1 to 0.4 K), while the clear-sky surface downward radiation is a significant cooling factor, contributing up to-0.5 K(-1.2 to 0.004 K), particularly in summer. However, the consistency of these models in simulating the impact of surface latent heat flux and albedo on surface temperature in China in response to deforestation is somewhat poor, highlighting the need to improve these related processes.
基金supported by grants from the Construction of Shaanxi Vegetable Industry Technology System in 2022[Grant No.NYKJ-2022-(XN)-03]the Construction of the Scientists+Engineers Team in Qin Chuangyuan,Shaanxi Province(Grant No.2023KXJ-024)。
文摘High atmospheric vapor pressure deficit(VPD)reduces the calcium(Ca)distribution in tomato(Solanum lycopersicum L.)fruits,severely reducing fruit mass.Reducing the VPD or increasing Ca fertilizer is an important measure to improve Ca distribution in fruits.However,the mechanism through which VPD and Ca regulate fruit Ca distribution remains unclear.This study investigated the effects of high and low VPD and Ca levels on Ca distribution and fruit mass based on carbon fixation,water transport dynamics,and pectin and Ca content and identified key differential genes and metabolites through transcriptome and metabolome analyses.The results showed that both reducing VPD under low Ca and increasing Ca under high VPD increased water and Ca transport to fruits.The increased Ca combined with pectin to form Ca pectinate,which effectively stabilized the cell wall and enhanced the fruit mass.Reduced VPD under low Ca increased the distribution of Ca to fruits but decreased the distribution of Ca to leaves.Lower Ca distribution in leaves increased their absorption of other nutrients,such as potassium,magnesium,copper,and zinc,which increased the stomatal size and density,thereby improving plant carbon absorption and assimilation efficiency.However,transcriptomic and metabolomic data indicated that carbohydrates,as important regulatory factors under drought stress,increased significantly under high VPD,thereby reducing the fruit water potential while improving fruit water and Ca absorption.Therefore,the carbon assimilation efficiency,water transport capacity,and differential genes and metabolites regulated Ca distribution.This work provides a theoretical basis for environmental and fertilizer management in greenhouse tomato production.
文摘Rapidly growing population,escalating urbanization,and industrialization are causing the depletion of non-renewable resources and air pollution,a silent pandemic responsible for billions of global mortalities.Sensors are crucial vectors for monitoring the emission of various gases/volatile organic compoundsbased pollutants from various anthropogenic sources.Borophene-based nanomaterials(BNMs)are the latest two-dimensional flatlands to this emergent next-generation sensors family with exceptional and tunable physicochemical attributes characterized by high anisotropy,thermal/mechanical resilience,tunable bandgaps,light-weight,high charge carrier mobility,and excellent adsorption efficacies.However,the practical implementation and scalability of BNMs grapple with challenges,including instability,substrateto-device transfer complications,and optimization intricacies.This comprehensive review delves into state-of-the-art BNM sensor fabrication techniques,intertwining theoretical insights derived from density functional theory and molecular dynamics with practical evaluations and on-site applications.Besides,the fundamental challenges associated with engineering BNM sensors and their alternate solutions by employing various strategies,including surface termination,functionalization,hydrogenation,hybridization,architecting composites,and green chemistry,are detailed.This review offers a roadmap from lab to market,bridging theoretical insights with practical implementation and expediting the advanced BNM sensors with wearable,remotely accessible,point-of-care,scavenging,self-powered,biocompatible,and intelligent modules for pollution management.
基金supported by the National Natural Science Foundation of China(Nos.52188101,52272051,52122202,12174086,and 12404009)High-level Talent Research Start-up Project Funding of Henan Academy of Sciences(No.231820055)+2 种基金the Fundamental Research Fund of Henan Academy of Sciences(No.240620057)the Scientific and Technological Research Project of Henan(No.242102230153)Cultivation and Enhancement Project of Technology Innovation Platform of Henan Academy of Sciences(No.241020004).
文摘Graphene meshes(GMs)have attracted considerable attention as advanced materials for high-performance gas sensing due to their high-density active edge sites and excellent electronic properties.However,the contamination-free preparation of GMs remains a challenge.Herein,we present a dewdrop-templated chemical vapor deposition approach to directly grow clean and intact graphene micromeshes(GMM)on SiO_(2)/Si substrates.The self-assembled micrometer-sized dewdrops from controlled water vapor condensation serve as a residue-free template for directing the growth of GMM with tunable hole sizes from submicrons to tens of microns.Density functional theory(DFT)calculations reveal that carbon species preferentially adsorb on pristine SiO_(2) regions to form a mesh structure.Contamination-free GMM gas sensors were fabricated using a simple transfer-free process,demonstrating a record-high sensitivity of 7.25%·ppm−1 and an ultra-low detection limit of 1.18 ppb for NO_(2) at room temperature.Complementary DFT studies elucidate that NO_(2) molecules adsorb more strongly on the edges of GMM,leading to a high response of the sensor.This work offers profound insights into dewdrop-templated graphene growth mechanisms and establishes a simple yet effective approach for fabricating high-performance transfer-free GMM sensors,thus paving the way for their practical applications in environmental monitoring and industrial safety fields.
