We proposed and compared three methods(filter burnup,single energy burnup,and burnup extremum analysis)to build a high-resolution neutronics model for 238Pu production in high-flux reactors.The filter burnup and singl...We proposed and compared three methods(filter burnup,single energy burnup,and burnup extremum analysis)to build a high-resolution neutronics model for 238Pu production in high-flux reactors.The filter burnup and single energy burnup methods have no theoretical approximation and can achieve a spectrum resolution of up to~1 eV,thereby constructing the importance curve and yield curve of the full energy range.The burnup extreme analysis method combines the importance and yield curves to consider the influence of irradiation time on production efficiency,thereby constructing extreme curves.The three curves,which quantify the transmutation rate of the nuclei in each energy region,are of physical significance because they have similar distributions.A high-resolution neutronics model for ^(238)Pu production was established based on these three curves,and its universality and feasibility were proven.The neutronics model can guide the neutron spectrum optimization and improve the yield of ^(238)Pu by up to 18.81%.The neutronics model revealed the law of nuclei transmutation in all energy regions with high spectrum resolution,thus providing theoretical support for high-flux reactor design and irradiation production of ^(238)Pu.展开更多
Laser wakefield accelerators （LWFAs） are considered to be one of the most compeuuve next- generation accelerator candidates. In this paper, we will study the potential high-flux electron beam production of an LWFA d...Laser wakefield accelerators （LWFAs） are considered to be one of the most compeuuve next- generation accelerator candidates. In this paper, we will study the potential high-flux electron beam production of an LWFA driven by petawatt-level laser pulses. In our three-dimensional particle-in-cell simulations, an optimal set of parameters gives -40 nC of charge with 2 PW laser power, thus -400 kA of instantaneous current if we assume the electron beam duration is 100 fs. This high flux and its secondary radiation are widely applicable in nuclear and QED physics, industrial imaging, medical and biological studies.展开更多
An experimental study of the gas-solid flow dynamics in the high-flux CFB riser was accomplished by analysing the scaling regions from solid concentration signals collected from a 76 mm internal diameters and 10 m hig...An experimental study of the gas-solid flow dynamics in the high-flux CFB riser was accomplished by analysing the scaling regions from solid concentration signals collected from a 76 mm internal diameters and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking (FCC) catalyst particles of 67 μm mean diameter and 1500 kg/m3 density together with 70% to 80% humid air was used. Solid concentration data were analysed using codes prepared in FORTRAN 2008 to get correlation integrals at different embedding dimensions and operating conditions and plot their profiles. Scaling regions were identified by visual inspection method and their location on planes determined. Scaling regions were analysed based on operating conditions and riser spatial locations. It was found that scaling regions occupy different locations on the plane depending on the number of embedding dimensions and operating conditions. As the number of embedding dimensions increases the spacing between scaling regions decreases until it saturates towards higher embedding dimensions. Slopes of scaling regions increases with embedding dimensions until saturation where they become constant. Slopes of scaling regions towards the wall decrease while the number of scaling regions for a particular profile increases. The span of the scaling region is wider at the initial values of hyperspherical radius than its final values. The scaling regions in some flow development sections show multifractal behaviour for each embedding dimension which manifests into visible basin which is defined in this study as multifractal basin. Further, the end points of the scaling region for each correlation integral profile differ from each other as the embedding dimension changes. This study suggests that identification of scaling region by visual inspection method is useful in understanding the gas-solid flow dynamics in the High-Flux CFB riser system. Further studies are recommended on risers of different diameters and heights operated at low and high solid fluxes and different gas velocities for comparison or usage of time series of different signal types like pressure fluctuations.展开更多
The study of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using trajectory distances of the reconstructed attractors from solid concentration signals collected from a 76 mm internal diam...The study of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using trajectory distances of the reconstructed attractors from solid concentration signals collected from a 76 mm internal diameters and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3 together with 70% to 80% humid air was used. Solid concentration data were analyzed using codes prepared in FORTRAN 2008 to get trajectories of the reconstructed attractors and their distances apart. Trajectory distances were found to increase from the centre towards the wall indicating the expansion of the attractor. The probability density function (PDF) of the trajectory distances changes from single peak at the centre to multiple peaked profiles in the wall region. Multiple peaked profiles indicate multifractal flow behaviours. Cumulative distribution functions (CDF) of the trajectory distances changes from single S-shaped at the centre to multiple S-shaped profiles in some locations of the wall region indicating multifractal flow behaviours. The PDF distribution of these distances at the entrance section and in the wall region forms different types of statistical distributions showing differences in gas-solid flow structures in various spatial locations of the wall region and the entrance sections. Most of the distributions at the centre fall under the Gumbel max distribution for all flow development sections of the riser, especially at air velocities of 5.5 m/s and 8 m/s showing uniform flow structures. Further, it was found that increase of the number of the phase space reconstruction embedding dimension increases the trajectory distances between the state vectors leading to the expansion of the attractor.展开更多
Analysis of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using embedded solid concentration time series collected from a 76 mm internal diameter and 10 m high riser of a circulating flui...Analysis of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using embedded solid concentration time series collected from a 76 mm internal diameter and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s air velocity and 50 to 550 kg/m2s solids flux of spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3. Data were analyzed using prepared FORTRAN 2008 code to get correlation integral followed by determination of correlation dimensions with respect to the hyperspherical radius and their profiles, plots of which were studied. It was found that correlation dimension profiles at the centre have single peak with higher values than the wall region profiles. Towards the wall, these profiles have double or multiple peaks showing bifractal or multifractal flow behaviors. As the velocity increases the wall region profiles become random and irregular. Further it was found that, as the height increases the correlation dimension profiles shift towards higher hyperspherical radius at the centre and towards lower hyperspherical radius in the wall region at r/R = 0.81. The established method of mapping correlation dimension profiles in this study forms a suitable tool for analysis of high-flux riser dynamics compared to other analyses approaches. However, further analysis is recommended to other gas-solid CFB riser of different dimensions operated at high-flux conditions using the established method.展开更多
Objective:To investigate the effects of high-flux hemodialysis on inflammatory factors and nutritional status in patients with severe renal failure.Methods:A total of 72 patients with severe renal failure who underwen...Objective:To investigate the effects of high-flux hemodialysis on inflammatory factors and nutritional status in patients with severe renal failure.Methods:A total of 72 patients with severe renal failure who underwent dialysis treatment in the hospital from January 2017 to March 2019 were selected as the research subjects,and they were randomly divided into 2 groups with 36 patients each.The control group underwent low-flux hemodialysis,and the observation group underwent high-flux hemodialysis.The levels of inflammatory factors and nutritional status were compared between the two groups after treatment.Results:The levels of various inflammatory factors in the observation group were lower than those in the control group and the nutritional indexes were higher than those in the control group after 4 weeks of treatment(P<0.05).Conclusion:High-throughput hemodialysis in patients with severe renal failure can significantly reduce the levels of inflammatory factors and improve nutritional status.展开更多
Hemodialysis is the main method of clinical renal replacement therapy, and its effectiveness and safety have been widely confirmed. High-flux hemodialysis, as a constantly updating new mode in the field of blood purif...Hemodialysis is the main method of clinical renal replacement therapy, and its effectiveness and safety have been widely confirmed. High-flux hemodialysis, as a constantly updating new mode in the field of blood purification, has effectively improved the efficiency of hemodialysis and reduced the incidence of hemodialysis complications. High-flux hemodialysis has been widely used in clinical practice, and mainly plays its role through adsorption, convection and dispersion. High-flux hemodialysis has some advantages not possessed by conventional hemodialysis, including protecting injured renal function, reducing the incidence of cardiovascular complications in hemodialysis patients, improving the patients' nutritional status, reducing the occurrence of renal osteopathy and delaying the occurrence time of dialysis-associated amyloidosis. However, high-flux hemodialysis also has some limitations, such as the elimination of drugs and nutrients, and the backfiltration caused by increased pressure on the dialysis membrane and dialysate side. In this review, the related progress of high-flux hemodialysis in clinical application, mechanism, complications and treatment are discussed in order to provide a reference for its more rational clinical use.展开更多
Objective:To study the effect of high-flux and low-flux hemodialysis on the side metabolites and cytokines in patients with uremia.Methods: A total of 50 patients with uremia who accepted high-flux hemodialysis and 14...Objective:To study the effect of high-flux and low-flux hemodialysis on the side metabolites and cytokines in patients with uremia.Methods: A total of 50 patients with uremia who accepted high-flux hemodialysis and 140 patients with uremia who accepted low-flux hemodialysis in our hospital between March 2015 and March 2016 were selected and included in high-flux group and low-flux group respectively. Before and after dialysis, serum was collected respectively to determine the levels of side metabolites, calcium-phosphorus metabolism indexes and cytokines.Results: 3 months after dialysis, serum Ca levels of two groups of patients were not significantly different from those before dialysis while BUN, Scr,β2-MG, sTfR, P, PTH and AKP levels were significantly lower than those before dialysis;3 months after dialysis, serum BUN, Scr and Ca levels of high-flux group were not significantly different from those of low-flux group whileβ2-MG, sTfR, P, PTH, AKP, TNF-α, IL-1β, IL-6, IL-8 and IL-10 levels were significantly lower than those of low-flux group.Conclusion:Compared with low-flux hemodialysis, high-flux hemodialysis treatment of uremia can more effectively remove middle molecular and macromolecular toxins, correct calcium-phosphorus metabolism disorder and relieve micro-inflammatory state.展开更多
Background Sustained hypotension during hemodialysis （HD） is an important clinical issue. Plasma adrenomedullin （AM） is increased in HD patients with sustained hypotension, but little is known about whether removi...Background Sustained hypotension during hemodialysis （HD） is an important clinical issue. Plasma adrenomedullin （AM） is increased in HD patients with sustained hypotension, but little is known about whether removing AM can improve hypotension. The objective of this study was to investigate the beneficial effects of hemodialysis using a high-flux dialyzer on removal of increased plasma AM levels and improving low blood pressure in elderly HD patients with sustained hypotension.Methods Forty-eight elderly patients （age 65 or older） who had undergone maintenance HD for more than one year were recruited and studied. We evaluated plasma levels of AM in sustained hypotension （SH; n=28） and normotensive （NT; n=20） patients. The patients with hypotension were further divided into two subgroups and treated with eitherhigh-flux dialyzer or low-flux dialyzer for 3 months. Plasma adrenomedullin levels and blood pressure were analyzed at days 0 and 181.Results Plasma levels of AM were significantly higher in SH than in NT patients （（24.92±3.7） ng/L vs. （15.52±6.01） ng/L,P〈0.05）, and were inversely correlated with mean arterial blood pressure （MAP） at pre-HD. After 3 months, the level of plasma AM in high-flux group was decreased （（24.58±4.36） ng/L vs. （16.18±5.08） ng/L, P 〈0.05）, but MAP was increased （（67.37±4.31） mmHg vs. （74.79±3.59） mmHg, P〈0.05）. There was no obvious change in low-flux group.Conclusions Plasma AM levels were significantly elevated in elderly HD patients with SH. High-flux dialyzer therapy can decrease plasma AM level and improve hypotension.展开更多
Particle clustering is an important dynamic phenomenon in circulating-fluidized-bed(CFBs)systems,and has been suggested as a key contributing factor to the non-uniform hydrodynamics of CFBs.Studies show that particle ...Particle clustering is an important dynamic phenomenon in circulating-fluidized-bed(CFBs)systems,and has been suggested as a key contributing factor to the non-uniform hydrodynamics of CFBs.Studies show that particle clusters can be affected by solids flux,in terms of frequency,duration,and solids holdup.To understand the characteristics of particle clusters under high-solids-flux conditions,experimental and modeling studies in high-solids-flux gas-solids CFBs were reviewed and summarized.Optical and electrical measurements and imaging methods were used to monitor the particle-clustering phenomenon in CFBs.Particles were found to cluster in high-flux CFBs,and were characterized by a denser cluster-solids holdup and a shorter time fraction,which was different from the behavior in low-flux CFBs.Particle properties affected particle clustering in high-flux CFBs significantly.In modeling work,Eulerian-Eulerian and Eulerian-Lagrangian methods were used to study the particle-cluster characteristics.Good results can be obtained by using the Eulerian-Eulerian method to simulate the CFB system,especially the high-flux CFBs,and by considering the effects of particle clusters.The Eulerian-Lagrangian method is used to obtain detailed cluster characteristics.Because of limits in computing power,no obvious results exist to model particle clusters under high-solids-flux conditions.Because high-solids-flux conditions are used extensively in industrial applications,further experimental and numerical investigations on the clustering behavior in HF/DCFBs are required.展开更多
Marine hydrate reservoirs can be divided into focused high-flux and distributed low-flux gas hydrate systems according to free gas migration control mechanisms. In focused high-flux hydrate reservoirs, fluids easily b...Marine hydrate reservoirs can be divided into focused high-flux and distributed low-flux gas hydrate systems according to free gas migration control mechanisms. In focused high-flux hydrate reservoirs, fluids easily break through the pressure of overlying sediments and reach the shallows, creating a series of geomorphological-geological-geophysical anomalies at and near the seafloor. Based on detailed interpretation of pre-drilling data in the eastern Pearl River Mouth Basin(PRMB),many anomalies related to the high-flux fluid flow are found, including seafloor mounds with intrusive characteristics, bright spot reflections above the bottom-stimulating reflector(BSR), phase reversals in the superficial layer, and an efficient fluid migration and accumulation system composed of fractures and uplifts. The second hydrate drilling expedition was carried out in the eastern PRMB in 2013 to study these anomalies. The acquired data show that high-flux fluid flow occurred in these sites. Gas hydrate pingoes, bright spot reflection above the BSR, and an efficient fluid migration and accumulation system can be used as identification signatures for high-flux fluid migration. The modes of high flux fluid flow are different in deep and shallow sediments during upward migration of fluid. Gas dissolved within migrating water dominates deep fluid migration and upward migration of a separate gas phase dominates the shallow process. This difference in migration models leads to formation of upper and lower concentrated hydrate reservoirs in the drilling area. The discovery of signatures of high-flux fluid flow and their migration modes will help with site selection and reduce risk in gas hydrate drilling.展开更多
A high-flux circulating fluidized bed （CFB） riser （0.076-m I.D. and 10-m high） was operated in a wide range of operating conditions to study its chaotic dynamics, using FCC catalyst particles （dp= 67μm, ρp = 15...A high-flux circulating fluidized bed （CFB） riser （0.076-m I.D. and 10-m high） was operated in a wide range of operating conditions to study its chaotic dynamics, using FCC catalyst particles （dp= 67μm, ρp = 1500 kg·m^-3）. Local solids concentration fluctuations measured using a reflective-type fiber optic probe were processed to determine chaotic invariants （Kolmogorov entropy and correlation dimension）, Radial and axial profiles of the chaotic invariants at different operating conditions show that the core region exhibits higher values of the chaotic invariants than the wall region. Both invariants vary strongly with local mean solids concentration. The transition section of the riser exhibits more complex dynamics while the bottom and top sections exhibit a more uniform macroscopic and less-complex microscopic flow structure. Increasing gas velocity leads to more complex and less predictable solids concentration fluctuations, while increasing solids flux generally lowers complexity and increases predictability. Very high solids flux, however, was observed to increase the entropy.展开更多
高通量工程试验堆(High Flux Engineering Test Reactor,HFETR)因其高中子通量密度,用于生产各种医用同位素。针对HFETR堆芯结构复杂、非均匀性强、辐照环境变化较大的特点,以“确定论燃料管理-蒙特卡罗粒子输运-产额”耦合计算的策略...高通量工程试验堆(High Flux Engineering Test Reactor,HFETR)因其高中子通量密度,用于生产各种医用同位素。针对HFETR堆芯结构复杂、非均匀性强、辐照环境变化较大的特点,以“确定论燃料管理-蒙特卡罗粒子输运-产额”耦合计算的策略建立了一套适用于不同类型同位素产额精确计算模型及方法。该方法首先通过研究堆专用燃料管理程序完成堆芯装载设计与燃耗计算,获得各时间步的燃料燃耗分布及临界棒位等参数,然后利用自编程序实现自动化全堆精细化建模,并利用蒙特卡罗方法完成输运计算。通过计算获得每一时间步下样品中不同核素与中子的反应率,通过产额求解程序与三维粒子输运蒙卡程序进行耦合,计算出下一个时间步样品内关键核素的含量变化情况,并对换料停堆和从出堆到测量期间的衰变损耗进行计算。该方法综合考虑了HFETR运行期间控制棒变化、燃料燃耗变化及计算燃耗步长的影响,利用HFETR已获得的同位素生产实验结果验证该套计算程序的准确性,对辐照88Sr生产89Sr产额的计算偏差为5.41%,对辐照生产32P产额的计算偏差为4.90%,对辐照生产177Lu产额的计算偏差为5.66%,与实验结果相比同位素产额计算偏差均在6%以内,证明该方法提高了同位素产额计算的精度,能够适用于研究堆生产同位素产额准确评估问题。展开更多
基金supported by Natural Science Foundation of China (No. 12305190)Lingchuang Research Project of China National Nuclear Corporation (CNNC)the Science and Technology on Reactor System Design Technology Laboratory
文摘We proposed and compared three methods(filter burnup,single energy burnup,and burnup extremum analysis)to build a high-resolution neutronics model for 238Pu production in high-flux reactors.The filter burnup and single energy burnup methods have no theoretical approximation and can achieve a spectrum resolution of up to~1 eV,thereby constructing the importance curve and yield curve of the full energy range.The burnup extreme analysis method combines the importance and yield curves to consider the influence of irradiation time on production efficiency,thereby constructing extreme curves.The three curves,which quantify the transmutation rate of the nuclei in each energy region,are of physical significance because they have similar distributions.A high-resolution neutronics model for ^(238)Pu production was established based on these three curves,and its universality and feasibility were proven.The neutronics model can guide the neutron spectrum optimization and improve the yield of ^(238)Pu by up to 18.81%.The neutronics model revealed the law of nuclei transmutation in all energy regions with high spectrum resolution,thus providing theoretical support for high-flux reactor design and irradiation production of ^(238)Pu.
基金supported by Extreme Light Infrastructure- Nuclear Physics (ELI-NP) Phase Ⅱa project co-financed by the Romanian Government and European Union through the European Regional Development FundThe EPOCH code project was funded by the UK EPSRC grants EP/G054950/1, EP/ G056803/1, EP/G055165/1 and EP/ M022463/1
文摘Laser wakefield accelerators （LWFAs） are considered to be one of the most compeuuve next- generation accelerator candidates. In this paper, we will study the potential high-flux electron beam production of an LWFA driven by petawatt-level laser pulses. In our three-dimensional particle-in-cell simulations, an optimal set of parameters gives -40 nC of charge with 2 PW laser power, thus -400 kA of instantaneous current if we assume the electron beam duration is 100 fs. This high flux and its secondary radiation are widely applicable in nuclear and QED physics, industrial imaging, medical and biological studies.
文摘An experimental study of the gas-solid flow dynamics in the high-flux CFB riser was accomplished by analysing the scaling regions from solid concentration signals collected from a 76 mm internal diameters and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking (FCC) catalyst particles of 67 μm mean diameter and 1500 kg/m3 density together with 70% to 80% humid air was used. Solid concentration data were analysed using codes prepared in FORTRAN 2008 to get correlation integrals at different embedding dimensions and operating conditions and plot their profiles. Scaling regions were identified by visual inspection method and their location on planes determined. Scaling regions were analysed based on operating conditions and riser spatial locations. It was found that scaling regions occupy different locations on the plane depending on the number of embedding dimensions and operating conditions. As the number of embedding dimensions increases the spacing between scaling regions decreases until it saturates towards higher embedding dimensions. Slopes of scaling regions increases with embedding dimensions until saturation where they become constant. Slopes of scaling regions towards the wall decrease while the number of scaling regions for a particular profile increases. The span of the scaling region is wider at the initial values of hyperspherical radius than its final values. The scaling regions in some flow development sections show multifractal behaviour for each embedding dimension which manifests into visible basin which is defined in this study as multifractal basin. Further, the end points of the scaling region for each correlation integral profile differ from each other as the embedding dimension changes. This study suggests that identification of scaling region by visual inspection method is useful in understanding the gas-solid flow dynamics in the High-Flux CFB riser system. Further studies are recommended on risers of different diameters and heights operated at low and high solid fluxes and different gas velocities for comparison or usage of time series of different signal types like pressure fluctuations.
文摘The study of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using trajectory distances of the reconstructed attractors from solid concentration signals collected from a 76 mm internal diameters and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3 together with 70% to 80% humid air was used. Solid concentration data were analyzed using codes prepared in FORTRAN 2008 to get trajectories of the reconstructed attractors and their distances apart. Trajectory distances were found to increase from the centre towards the wall indicating the expansion of the attractor. The probability density function (PDF) of the trajectory distances changes from single peak at the centre to multiple peaked profiles in the wall region. Multiple peaked profiles indicate multifractal flow behaviours. Cumulative distribution functions (CDF) of the trajectory distances changes from single S-shaped at the centre to multiple S-shaped profiles in some locations of the wall region indicating multifractal flow behaviours. The PDF distribution of these distances at the entrance section and in the wall region forms different types of statistical distributions showing differences in gas-solid flow structures in various spatial locations of the wall region and the entrance sections. Most of the distributions at the centre fall under the Gumbel max distribution for all flow development sections of the riser, especially at air velocities of 5.5 m/s and 8 m/s showing uniform flow structures. Further, it was found that increase of the number of the phase space reconstruction embedding dimension increases the trajectory distances between the state vectors leading to the expansion of the attractor.
文摘Analysis of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using embedded solid concentration time series collected from a 76 mm internal diameter and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s air velocity and 50 to 550 kg/m2s solids flux of spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3. Data were analyzed using prepared FORTRAN 2008 code to get correlation integral followed by determination of correlation dimensions with respect to the hyperspherical radius and their profiles, plots of which were studied. It was found that correlation dimension profiles at the centre have single peak with higher values than the wall region profiles. Towards the wall, these profiles have double or multiple peaks showing bifractal or multifractal flow behaviors. As the velocity increases the wall region profiles become random and irregular. Further it was found that, as the height increases the correlation dimension profiles shift towards higher hyperspherical radius at the centre and towards lower hyperspherical radius in the wall region at r/R = 0.81. The established method of mapping correlation dimension profiles in this study forms a suitable tool for analysis of high-flux riser dynamics compared to other analyses approaches. However, further analysis is recommended to other gas-solid CFB riser of different dimensions operated at high-flux conditions using the established method.
文摘Objective:To investigate the effects of high-flux hemodialysis on inflammatory factors and nutritional status in patients with severe renal failure.Methods:A total of 72 patients with severe renal failure who underwent dialysis treatment in the hospital from January 2017 to March 2019 were selected as the research subjects,and they were randomly divided into 2 groups with 36 patients each.The control group underwent low-flux hemodialysis,and the observation group underwent high-flux hemodialysis.The levels of inflammatory factors and nutritional status were compared between the two groups after treatment.Results:The levels of various inflammatory factors in the observation group were lower than those in the control group and the nutritional indexes were higher than those in the control group after 4 weeks of treatment(P<0.05).Conclusion:High-throughput hemodialysis in patients with severe renal failure can significantly reduce the levels of inflammatory factors and improve nutritional status.
文摘Hemodialysis is the main method of clinical renal replacement therapy, and its effectiveness and safety have been widely confirmed. High-flux hemodialysis, as a constantly updating new mode in the field of blood purification, has effectively improved the efficiency of hemodialysis and reduced the incidence of hemodialysis complications. High-flux hemodialysis has been widely used in clinical practice, and mainly plays its role through adsorption, convection and dispersion. High-flux hemodialysis has some advantages not possessed by conventional hemodialysis, including protecting injured renal function, reducing the incidence of cardiovascular complications in hemodialysis patients, improving the patients' nutritional status, reducing the occurrence of renal osteopathy and delaying the occurrence time of dialysis-associated amyloidosis. However, high-flux hemodialysis also has some limitations, such as the elimination of drugs and nutrients, and the backfiltration caused by increased pressure on the dialysis membrane and dialysate side. In this review, the related progress of high-flux hemodialysis in clinical application, mechanism, complications and treatment are discussed in order to provide a reference for its more rational clinical use.
文摘Objective:To study the effect of high-flux and low-flux hemodialysis on the side metabolites and cytokines in patients with uremia.Methods: A total of 50 patients with uremia who accepted high-flux hemodialysis and 140 patients with uremia who accepted low-flux hemodialysis in our hospital between March 2015 and March 2016 were selected and included in high-flux group and low-flux group respectively. Before and after dialysis, serum was collected respectively to determine the levels of side metabolites, calcium-phosphorus metabolism indexes and cytokines.Results: 3 months after dialysis, serum Ca levels of two groups of patients were not significantly different from those before dialysis while BUN, Scr,β2-MG, sTfR, P, PTH and AKP levels were significantly lower than those before dialysis;3 months after dialysis, serum BUN, Scr and Ca levels of high-flux group were not significantly different from those of low-flux group whileβ2-MG, sTfR, P, PTH, AKP, TNF-α, IL-1β, IL-6, IL-8 and IL-10 levels were significantly lower than those of low-flux group.Conclusion:Compared with low-flux hemodialysis, high-flux hemodialysis treatment of uremia can more effectively remove middle molecular and macromolecular toxins, correct calcium-phosphorus metabolism disorder and relieve micro-inflammatory state.
基金This work was supported by the grants from the National Basic Research Program （973 Program） of China （No. 2007CB507400）, the National Natural Science Foundation of China （No. 30871171）, and the Military ＂Eleven-five＂ Special Fund of Medical Science （No. 08Z034）.
文摘Background Sustained hypotension during hemodialysis （HD） is an important clinical issue. Plasma adrenomedullin （AM） is increased in HD patients with sustained hypotension, but little is known about whether removing AM can improve hypotension. The objective of this study was to investigate the beneficial effects of hemodialysis using a high-flux dialyzer on removal of increased plasma AM levels and improving low blood pressure in elderly HD patients with sustained hypotension.Methods Forty-eight elderly patients （age 65 or older） who had undergone maintenance HD for more than one year were recruited and studied. We evaluated plasma levels of AM in sustained hypotension （SH; n=28） and normotensive （NT; n=20） patients. The patients with hypotension were further divided into two subgroups and treated with eitherhigh-flux dialyzer or low-flux dialyzer for 3 months. Plasma adrenomedullin levels and blood pressure were analyzed at days 0 and 181.Results Plasma levels of AM were significantly higher in SH than in NT patients （（24.92±3.7） ng/L vs. （15.52±6.01） ng/L,P〈0.05）, and were inversely correlated with mean arterial blood pressure （MAP） at pre-HD. After 3 months, the level of plasma AM in high-flux group was decreased （（24.58±4.36） ng/L vs. （16.18±5.08） ng/L, P 〈0.05）, but MAP was increased （（67.37±4.31） mmHg vs. （74.79±3.59） mmHg, P〈0.05）. There was no obvious change in low-flux group.Conclusions Plasma AM levels were significantly elevated in elderly HD patients with SH. High-flux dialyzer therapy can decrease plasma AM level and improve hypotension.
基金This work was supported by the National Natural Science Foundation of China(grant numbers 91534204,21622609,and 21506253)the Science Foundation of China University of Petroleum,Beijing(grant numbers 2462018BJC003 and 2462014YJRC018).
文摘Particle clustering is an important dynamic phenomenon in circulating-fluidized-bed(CFBs)systems,and has been suggested as a key contributing factor to the non-uniform hydrodynamics of CFBs.Studies show that particle clusters can be affected by solids flux,in terms of frequency,duration,and solids holdup.To understand the characteristics of particle clusters under high-solids-flux conditions,experimental and modeling studies in high-solids-flux gas-solids CFBs were reviewed and summarized.Optical and electrical measurements and imaging methods were used to monitor the particle-clustering phenomenon in CFBs.Particles were found to cluster in high-flux CFBs,and were characterized by a denser cluster-solids holdup and a shorter time fraction,which was different from the behavior in low-flux CFBs.Particle properties affected particle clustering in high-flux CFBs significantly.In modeling work,Eulerian-Eulerian and Eulerian-Lagrangian methods were used to study the particle-cluster characteristics.Good results can be obtained by using the Eulerian-Eulerian method to simulate the CFB system,especially the high-flux CFBs,and by considering the effects of particle clusters.The Eulerian-Lagrangian method is used to obtain detailed cluster characteristics.Because of limits in computing power,no obvious results exist to model particle clusters under high-solids-flux conditions.Because high-solids-flux conditions are used extensively in industrial applications,further experimental and numerical investigations on the clustering behavior in HF/DCFBs are required.
基金supported by the National Natural Science Foundation of China (Grant No. 41406068)
文摘Marine hydrate reservoirs can be divided into focused high-flux and distributed low-flux gas hydrate systems according to free gas migration control mechanisms. In focused high-flux hydrate reservoirs, fluids easily break through the pressure of overlying sediments and reach the shallows, creating a series of geomorphological-geological-geophysical anomalies at and near the seafloor. Based on detailed interpretation of pre-drilling data in the eastern Pearl River Mouth Basin(PRMB),many anomalies related to the high-flux fluid flow are found, including seafloor mounds with intrusive characteristics, bright spot reflections above the bottom-stimulating reflector(BSR), phase reversals in the superficial layer, and an efficient fluid migration and accumulation system composed of fractures and uplifts. The second hydrate drilling expedition was carried out in the eastern PRMB in 2013 to study these anomalies. The acquired data show that high-flux fluid flow occurred in these sites. Gas hydrate pingoes, bright spot reflection above the BSR, and an efficient fluid migration and accumulation system can be used as identification signatures for high-flux fluid migration. The modes of high flux fluid flow are different in deep and shallow sediments during upward migration of fluid. Gas dissolved within migrating water dominates deep fluid migration and upward migration of a separate gas phase dominates the shallow process. This difference in migration models leads to formation of upper and lower concentrated hydrate reservoirs in the drilling area. The discovery of signatures of high-flux fluid flow and their migration modes will help with site selection and reduce risk in gas hydrate drilling.
文摘A high-flux circulating fluidized bed （CFB） riser （0.076-m I.D. and 10-m high） was operated in a wide range of operating conditions to study its chaotic dynamics, using FCC catalyst particles （dp= 67μm, ρp = 1500 kg·m^-3）. Local solids concentration fluctuations measured using a reflective-type fiber optic probe were processed to determine chaotic invariants （Kolmogorov entropy and correlation dimension）, Radial and axial profiles of the chaotic invariants at different operating conditions show that the core region exhibits higher values of the chaotic invariants than the wall region. Both invariants vary strongly with local mean solids concentration. The transition section of the riser exhibits more complex dynamics while the bottom and top sections exhibit a more uniform macroscopic and less-complex microscopic flow structure. Increasing gas velocity leads to more complex and less predictable solids concentration fluctuations, while increasing solids flux generally lowers complexity and increases predictability. Very high solids flux, however, was observed to increase the entropy.
文摘高通量工程试验堆(High Flux Engineering Test Reactor,HFETR)因其高中子通量密度,用于生产各种医用同位素。针对HFETR堆芯结构复杂、非均匀性强、辐照环境变化较大的特点,以“确定论燃料管理-蒙特卡罗粒子输运-产额”耦合计算的策略建立了一套适用于不同类型同位素产额精确计算模型及方法。该方法首先通过研究堆专用燃料管理程序完成堆芯装载设计与燃耗计算,获得各时间步的燃料燃耗分布及临界棒位等参数,然后利用自编程序实现自动化全堆精细化建模,并利用蒙特卡罗方法完成输运计算。通过计算获得每一时间步下样品中不同核素与中子的反应率,通过产额求解程序与三维粒子输运蒙卡程序进行耦合,计算出下一个时间步样品内关键核素的含量变化情况,并对换料停堆和从出堆到测量期间的衰变损耗进行计算。该方法综合考虑了HFETR运行期间控制棒变化、燃料燃耗变化及计算燃耗步长的影响,利用HFETR已获得的同位素生产实验结果验证该套计算程序的准确性,对辐照88Sr生产89Sr产额的计算偏差为5.41%,对辐照生产32P产额的计算偏差为4.90%,对辐照生产177Lu产额的计算偏差为5.66%,与实验结果相比同位素产额计算偏差均在6%以内,证明该方法提高了同位素产额计算的精度,能够适用于研究堆生产同位素产额准确评估问题。
