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Scale-up studies of fluidized beds are important for numerous fields. Fluidization in a multi-ring inclined nozzle spout-fluid bed (MRIN spout-fluid bed) is one of the most critical factors that affect the coating efficiency and uniformity of tri-structural isotropic (TRISO) nuclear particles in the fluidized bed chemical vapor deposition (FB-CVD) process. In this work, the flow pattern similarity principle was proposed to scale up a specially designed spout-fluid bed, which was aimed at maintaining the gas-solid contact efficiency, and was validated by electrical capacitance tomography (ECT) measurements. First, the traditional ECT method was developed for the specially designed MRIN spout-fluid bed according to the filling method. Then, the reconstruction algorithms were updated using the alternating direction multiplier method (ADMM) by introducing optimization constraints. The fluidization laws were investigated for different superficial gas velocities and distributor structures. We found that the gas distributor structure affected the merge point of the jets, which played an essential role in fluidization pattern changes. The statistically-based coefficient of variation (Cv) was proposed to distinguish the different flow patterns. Multi-ring spouting was then selected as a typical flow pattern for good fluidization and mixing, where the Cv ranged from 0.25 to 0.65. Then, the optimal design principles for the enlarged spout-fluid bed gas distributor were obtained. We determined that a smaller nozzle diameter (0.71d 0), larger nozzle spacing (1.12x 0), and slightly inclined angle (1.50θ 0) could improve fluidization, and that nozzle spacing was the most important factor. This study may be beneficial for the industrial design of the FB-CVD process and for the fabrication of high-density nuclear fuel particles. Additionally, it could be presented to a more general audience for scaling-up fluidized beds with a complex distributor, which would be beneficial for the fluidization research community.

Using inclined vibrating plate (IVP) to gather spherical coated fuel particles is an important process in nuclear fuel particulate technology, especially in the manufacture of nuclear fuel elements for high-temperature gas-cooled reactor (HTGR). In order to get a satisfactory separation result, fuel particles are required to discharge uniformly and slowly into the IVP at a stable flow rate. To this end, the vibrating feeding system composed of a hopper and a new designed multi-layer multi-channel (MLMC) feeder is proposed in this paper to increase the discharge rate, optimize the uniformity of particle distribution and reduce the particle velocity near the outlet, which can produce a better separation of odd fuel particles. Subsequently, discrete element method (DEM) is used to investigate the motion of coated fuel particles in the feeding hopper. The accuracy of DEM is verified by comparing the experimental results with the simulation results. At the same time, the mass discharge rate (MDR) of particles in the hopper and the influence of geometry structure of hopper are studied. Finally, the motion of fuel particles in the new designed MLMC feeder is investigated, and the distribution characteristics of particles discharging out from the new feeder are analyzed. The simulation results demonstrate that the new designed feeding system can meet the optimal feeding requirements that the particles are discharged uniformly with the rather stable flow rate and the relatively lower particle velocity.

Odd-shaped coated nuclear fuel particles are the main reason for the failure in the manufacture of fuel element, and the sphericity separation of fuel particles is one of the most significant process to improve the safety of high-temperature gas-cooled reactor (HTGR). The separation of particles by inclined vibrating plate (IVP) is based on the different friction force acted by the distinct shapes of particles. In this paper, Discrete element method (DEM), which is a numerical simulation method for analyzing and solving the dynamic properties of discrete systems, is used to investigate the separation process on the IVP. In view of the realistic fuel particles are all non-spherical particles with irregular shape, the super-ellipsoid model is utilized to describe the particles in the DEM simulation. A method to evaluate the separation efficiency is proposed in this paper to quantify the numerical simulation results of particle sphericity separation. The relationship among the operating parameters such as amplitude, frequency and inclination angle is combed, and the selection of the optimal value of these parameters are obtained. The effects of feeding-rate and height of feeder are investigated, and the particle collision is analyzed to explain the effect of feeding-rate. A set of optimized parameters are proposed, and it is identified that the DEM simulation results received by using these parameters meet the requirement of the fabrication process of coated fuel particles.

Anti-nuclear antibodies to speckled 100 kDa (sp100) and glycoprotein 210 (gp210) are specific serologic markers of primary biliary cholangitis (PBC) of uncertain/controversial clinical or prognostic significance. To study the genetic determinants associated with sp100 and gp210 autoantibody subphenotypes, we performed a genome-wide association analysis of 930 PBC cases based on their autoantibody status, followed by a replication study in 1,252 PBC cases. We confirmed single-nucleotide polymorphisms rs492899 (P = 3.27 × 10-22 ; odds ratio [OR], 2.90; 95% confidence interval [CI], 2.34-3.66) and rs1794280 (P = 5.78 × 10-28 ; OR, 3.89; 95% CI, 3.05-4.96) in the human major histocompatibility complex (MHC) region associated with the sp100 autoantibody. However, no genetic variant was identified as being associated with the gp210 autoantibody. To further define specific classical human leukocyte antigen (HLA) alleles or amino acids associated with the sp100 autoantibody, we imputed 922 PBC cases (211 anti-sp100-positive versus 711 negative cases) using a Han Chinese MHC reference database. Conditional analysis identified that HLA-DRβ1-Asn77/Arg74, DRβ1-Ser37, and DPβ1-Lys65 were major determinants for sp100 production. For the classical HLA alleles, the strongest association was with DRB1*03:01 (P = 1.51 × 10-9 ; OR, 2.97; 95% CI, 2.06-4.29). Regression analysis with classical HLA alleles identified DRB1*03:01, DRB1*15:01, DRB1*01, and DPB1*03:01 alleles can explain most of the HLA association with sp100 autoantibody. Conclusion: This study indicated significant genetic predisposition to the sp100 autoantibody, but not the gp210 autoantibody, subphenotype in PBC patients. Additional studies will be necessary to determine if these findings have clinical significance to PBC pathogenesis and/or therapeutics.

Particle coating is a very important step in many industrial production processes as the particle coating layers may fix surfaces with unique advantages. Given the limitation and disadvantages of the existing simulation methods, a coupled CFD–DEM–CVD multi-physical field model for particle-coating simulations has been established taking into account the velocity field, temperature field, concentration field, and deposition model. In this model, gas behavior and chemical reactions are simulated in the CFD frame based on the conservation laws of mass, momentum, and energy. The particle behavior is simulated in the DEM frame based on the gas–solid interphase force model and contact force model. The deposition behavior is simulated in the CVD frame based on the particle movement–adhesion–deposition model. The coupled model can be implemented in Fluent-EDEM software with their user definition function and application programming interface. The particle coating process involving the pyrolysis of acetylene was investigated, and the effect of bed temperature and inlet gas velocity on deposition rate and coating efficiency were investigated based on the proposed model with adjustable deposition coefficients. Both the average deposition layer mass and the average deposition layer thickness were found to be proportional to the elapsed time and increased at the rate of about 1.05 × 10−2 mg/s and 3.45 × 10−4 mm/s, respectively, setting the inlet gas velocity to 11 m/s and bed temperature to 1680 K. A higher temperature and larger inlet gas velocity lead to a larger deposition rate, but the coating efficiency decreases because of limits imposed by the chemical reaction. At a bed temperature of 1280 K, the average deposition rate is 7.40 × 10−3 mg/s when the inlet gas velocity is set to 11 m/s, which is about double the deposition rate when the inlet gas velocity is set as 5 m/s. The proposed model can provide some guidance for the operating conditions and parameters design of the spouted bed in actual coating settings and can also be further developed as a basic model of mechanisms to integrate detailed information across multiple scales.

Background The roots of Gynura japonica are used as traditional medicine for treating blood stasis or traumatic injury even though hundreds of hepatic sinusoidal obstruction syndrome cases have been reported after consumption of the roots, which contain large amounts of hepatotoxic pyrrolizidine alkaloids (HPAs). However, no information is available about the toxic compounds in the aerial parts of G. japonica, which are also used as herbal medicines and even vegetables in several areas. Thus, the toxic chemicals in the aerial parts of G. japonica, i.e., HPAs, must be urgently identified. Purpose In this study, we aimed to 1) identify the toxic compounds in different medicinal parts and 2) examine the hepatotoxicity of G. japonica. Study design A total of 35 batches of the roots and aerial parts of G. japonica were collected from different sources and analyzed for HPAs. The hepatotoxicity of different extracts (i.e., total extracts [TE] and total alkaloids [TA]) and a single compound (i.e., senecionine) was evaluated on mice. Methods Qualitative analysis of HPAs was performed using an ultra-performance liquid chromatography (UPLC)-mass spectrometry (MS)-parent ion scan approach, whereas a quantitative assay was performed by a UPLC-MS-selected ion monitoring approach. Male C57BL mice were orally administered the different extracts or the single compound at dosages equivalent to 50 mg HPAs/kg body weight. The sera and the livers were collected at 48 h after treatment and used to evaluate the hepatotoxicity through serum clinical biomarkers assay, liver histology, and bile acid profiling. Results A total of 21 HPAs were identified in the roots and the aerial parts. The roots contained higher levels of HPAs (4.90 mg/g) than did the aerial parts (2.21 mg/g). TE and TA induced similar acute liver injuries, but senecionine was considerably more toxic than these extracts. Mice treated with TE showed significantly impaired bile acid homeostasis in the sera and the livers. Conclusion The roots and aerial parts of G. japonica contained large amounts of HPAs, including senecionine, which were responsible for the hepatotoxicity of G. japonica. Bile acid homeostasis was uniquely impaired after exposure to the plant. Therefore, neither the roots nor the aerial parts of G. japonica should be consumed as medicines or vegetables.

Particle mixing is a very important process in many industrial reactors. It is important to consider how to quantify the particle mixing behavior accurately under different conditions. In this paper, the drawbacks of traditional mixing indexes, such as Lacey index are discussed, and then a novel particle mixing index, without grid dependency and particle color dependency was proposed based on the neighbor distance method and coordination number concept. Its characteristics such as parameters selection, calculation method and multi-direction were discussed in details. The proposed mixing index was used for investigating particle mixing behavior in the multiple-spouted bed under conditions of different gas velocity ratios and different particle density ratios. The experimental results have been used to validate the simulation results at first. It is found that the improved mixing index is more superior and effective compared with the traditional mixing index methods, and suitable for the investigation of particle mixing behavior. It was indicated that the density ratio is a key factor to influence particle mixing process. The novel particle mixing index without grid dependency and particle color dependency is recommended to study particle mixing behavior in other particulate processes in the future.

The present work focused on fundamentally modelling of the fluidized bed chemical vapor deposition (FB-CVD) process, which is the extensively used method to prepare TRISO particles and other types coated particles, aimed at optimizing and scaling up of the coated fuel particles fabrication technology using a mechanistic approach rather than empirical knowledge. Based on the experimental observation of the coating process, the population balance model (PBM) was used to describe the size distribution of nanoparticles in the FB-CVD process. The deposition rate model related to nanoparticle size distribution was developed based on the homogeneous and heterogeneous deposition coexistence mechanism. Furthermore, on a macroscopic scale, the computational fluid dynamics (CFD) and discrete element method (DEM) were coupled with the deposition rate model, establishing a multiscale simulation platform for simulating the FB-CVD particle coating process. In this proposed CFD-DEM-PBM model, the mass, momentum, and energy transfer, along with chemical reaction, nanoparticle formation, deposition along homogeneous and heterogeneous pathways were considered and simulated accordingly. The preliminary study has been conducted successfully and indicates that the proposed multiscale model has clear and important significance for investigating the particle coating process. However, it should be noted that the model parameters still need to be experimentally refined in the future.

Vibration sorting is a common means in separating non-spherical particles from spherical particles. In this paper, the discrete element method (DEM) is applied to simulate the behavior of spherical particles and non-spherical particles motion on an inclined vibrating plate (IVP), and the influence of different operating parameters on the separation performance of the mixed particles is investigated. In the DEM simulations, both the spherical and non-spherical particles are modeled by super-ellipsoids. The simulation results show that the optimal vibration amplitude and frequency exist for the high separation efficiency of the mixed particles. The separation efficiency can also be enhanced by properly increasing the friction coefficient or decreasing the restitution coefficient between particles and plate. It is easier to separate the non-spherical particles from the spherical particles by diminishing the sphericity of particles. Besides, as long as the inclination angle of the plate is set at appropriate range and the feed rate of the mixed particles is moderate, the non-spherical particles can be separated effectively from the spherical particles. This research could be helpful for the understanding and optimal design of vibration sorting device.

Particle coating is an important method that can be used to expand particle-technology applications. Coated-particle design and preparation for nuclear fuel-element trajectory tracing were focused on in this paper. Particles that contain elemental cobalt were selected because of the characteristic gamma ray spectra of 60Co. A novel particle-structure design was proposed by coating particles that contain elemental cobalt with a high-density silicon-carbide (SiC) layer. During the coating process with the high-density SiC layer, cobalt metal was formed and diffused towards the coating, so an inner SiC–CoxSi layer was designed and obtained by fluidized-bed chemical vapor deposition coupled with in-situ chemical reaction. The coating layers were studied by X-ray diffractometry, scanning electron microscopy, and energy dispersive X-ray spectroscopy techniques. The chemical composition was also determined by inductively coupled plasma optical emission spectrometry. The novel particle design can reduce the formation of metallic cobalt and prevent cobalt diffusion in the coating process, which can maintain safety in a nuclear reactor for an extended period. The experimental results also validated that coated particles maintain their structural integrity at extremely high temperatures (∼1950 °C), which meets the requirements of next-generation nuclear reactors.

Objectives: Pyrrolizidine alkaloids-induced hepatic sinusoidal obstruction syndrome (PA-HSOS) has been reported to have high mortality. Limited data were available about the outcomes of anticoagulation therapy in PA-HSOS. We aimed to evaluate the efficacy and safety of anticoagulation therapy for the patients with PA-HSOS and also to explore the possible predictors for anticoagulation efficacy. Methods: We collected clinical data on a total of 249 PA-HSOS patients from January 2012 to December 2017 at 4 tertiary care hospitals in China. 151 patients received anticoagulation therapy plus symptomatic treatment, and 98 patients received symptomatic treatment. The efficacy and safety outcomes were analyzed using Fine and Gray competing risk analysis method and Cox regression model. The predictors for complete response to anticoagulation therapy in PA-HSOS patients were investigated using clinical data. Results: The cumulative complete response rate was higher in the anticoagulation group than in the supportive group (60.9% vs36.7%, adjusted HR, 4.51; p

The genetic association of primary biliary cholangitis with major histocompatibility complex (MHC) has been widely confirmed among different ethnicities. To map specific MHC region variants associated with PBC in a Han Chinese cohort, we imputed HLA antigens and amino acids (AA) in 1126 PBC cases and 1770 healthy control subjects using a Han-MHC reference database. We demonstrate that HLA-DRB1 and/or HLA-DQB1 contributed the strongest signals, and that HLA-DPB1 was a separate independent locus. Regression analyses with classical HLA alleles indicate that HLA-DQB1*03:01 or HLA-DQβ1-Pro55, HLA-DPB1*17:01 or HLA-DPβ1-Asp84 and HLA-DRB1*08:03 could largely explain MHC association with PBC. Forward stepwise regression analyses with HLA amino acid variants localize the major signals to HLA-DRβ1-Ala74, HLA-DQβ1-Pro55 and HLA-DPβ1-Asp84. Electrostatic potential calculations implicated AA variations at HLA-DQβ1 position 55 and HLA-DPβ1 position 84 as critical to peptide binding properties. Furthermore, although several critical Han Chinese AA variants differed from those shown in European populations, the predicted effects on antigen binding are likely to be very similar or identical and underlie the major component of MHC association with PBC.

Electrical capacitance tomography (ECT) is widely used in research for different applications, e.g. in the petroleum, pharmaceutical and power industries, due to its nonintrusive and noninvasive features and low cost. So far, ECT has been successfully used with regular structures, such as circular and square shapes. However, in some cases, the measurement electrodes cannot be mounted directly on an irregular structure, high temperature objects or corrosive objects. In this work, a method is proposed for ECT to be used with an irregular structure, by filling the gap between the irregular structure and a regular ECT sensor wall. Accordingly, a split matrix method is proposed for image reconstruction. The characteristics of sensitivity maps with the filling method and different structures are investigated. To calculate sensitivity maps, two methods are used: the perturbation method and the potential method, and their effects on image quality are compared. The results show that there is no obvious difference between these two methods for imaging construction, but the potential method is more efficient than the perturbation method. Among different shapes, an image of a triangular object has a large deformation due to its sharp angle and hence the filling method is not suitable for imaging a triangular object. The split matrix method modified by relaxation factors is suitable for irregular structures in general and can generate satisfactory images. A hardware system based on an impedance analyser and a software package have been developed and used to validate the proposed methods. The experimental results show that the proposed method is promising for imaging two-phase flows in irregular structures.

Tristructural-isotropic (TRISO) particle has been successful in high temperature gas cooled reactor (HTGR), but an improved design is required for future development. In this paper, the coating layers are reconsidered, and an improved design of TRISO particle with porous SiC inner layer is proposed. Three methods of preparing the porous SiC layer, called high methyltrichlorosilane (MTS) concentration method, high Ar concentration method and hexamethyldisilane (HMDS) method, are experimentally studied. It is indicated that porous SiC layer can be successfully prepared and the density of SiC layer can be adjusted by tuning the preparation parameters. Microstructure and characterization of the improved TRISO coated particle are given based on scanning electron microscope (SEM), X-ray diffraction (XRD), Raman scattering and energy dispersive X-ray (EDX) analysis. It can be found that the improved TRISO coated particle with porous SiC layer can be mass produced successfully. The formation mechanisms of porous SiC layer are also discussed based on the fluidized bed-chemical vapor deposition principle.

High flexible SiC nanowires with diameters in the range of 10 to 50 nm and lengths of several hundred micrometers to several millimeters are synthesized using a novel catalyst-assisted fluidized bed chemical vapor deposition method. Methyltrichlorosilane (MTS) is used as source material and particles containing cobalt were used as catalyst. The fluidized bed is specially designed to form a perpendicular uneven temperature distribution. Suspended nanosized liquid catalyst droplets are produced at middle high temperature zone and SiC nanowires are formed in situ on the catalyst droplets then accumulated at the upper part of fluidized bed. The nanowires exhibit a single crystal feature with some stacking faults. Transmission electron microscopy (TEM) analysis verifies a growth direction along the axis of the nanowires. A blue shift optical emission band at about 420 nm is detected using photoluminescence spectroscopy. From the high-resolution TEM investigation, a nanoscale smooth plane between the nanowire and the catalyst tip is observed and the two phases exhibit highly epitaxial growth interface. The growth process of the nanowires is discussed and a possible formation mechanism is proposed.

CFD–DEM coupling simulation method is used to study the fluidization behavior of particle with different densities in the spouted bed. The simulation results show that the particle spouting behavior is incoherent and periodic in the stable spouting state. The cycle periods of the whole bed and single particle are obtained from particle trajectory and compared with experimental results. The relationships between the minimum spouting gas velocity, the steady pressure drop and the particle density are obtained. It can be found that the gas velocity range of stable spouting state expands when the particle density increases. The dual, single and multiple dominant frequencies are found in the stable spouting process of high density particle. Through detailed analysis on the mechanism of spouting dominant frequency, the flow pattern map with different superficial gas velocities and particle densities is given and can be divided into five regions: fixed bed with internal spouting, transitional stable spouting state with dual dominant frequency, main stable spouting state with single dominant frequency, transitional stable spouting state with multiple dominant frequency, and unstable spouting state. The stable spouting gas velocity is influenced by the particle density, while the dominant frequency of the particle spouting process will keep invariant even if the particle density increases, as long as Ug/Ums is not changed. The influence of particle density on the particle residence time distribution in the spout region, which can be used to characterize the gas solid contact efficiency, is also discussed based on simulation results.

Different methods of particle mixing index are summarized in detail, such as average height method, nearest neighbour method, neighbour distance method, Lacey method, mixing entropy method, coordination number method, particle-scale index method and Siiria method. All these particle mixing indexes are calculated in two classical particle related process, that are the rotating drum and the spouted bed based on simulation results using DEM method. Then the comparative analysis of different kinds of particle mixing index is given in different aspects, such as calculation complexity, parameter dependency, grid dependency, color dependency and direction dependency. The performances of different particle mixing indexes are evaluated, the advantages and disadvantages of different indexes are pointed out, and the recommendation adaptation ranges are given finally. General speaking, the neighbour distance method seems as the best choice for studying the particle mixing process because of its superior performance.

In this paper, the whole system of coating furnace is simulated based on 3D single phase simulation to optimize the FB-CVD (Fluidized Bed-Chemical Vapour Deposition) reactor structure design, which is called the multiple-ring inclined-nozzle spouted bed. The spouted bed with present and enlarged diameter for two times of production, were simulated using a 3D CFD model in a complex geometry, aimed at proposing a quick scale-up strategy of the coating furnace. A new scale-up criterion is proposed and discussed based on single-phase two-component simulation results, which were central-inlet gas concentration distribution at different furnace heights. Four cases of the newly design with enlarged diameter of spouted bed was compared quantitatively, and one was recommended to use firstly in the coating experiments based on the newly proposed scale-up criterion. The present China SFE (Spherical Fuel Element) commercial production line (300000 SFEs per year) will be updated based on the present scale-up research results, aimed at providing the SPE for the HTR-PM600 in the future.

High temperature oxidation behavior of SiC coatings in tristructural-isotropic (TRISO) coated particles is crucial to the in-pile safety of fuel particles for a high temperature gas cooled reactor (HTGR). The postulated accident condition of air ingress was taken into account in evaluating the reliability of the SiC layer. Oxidation tests of SiC coatings were carried out in the ranges of temperature between 800 and 1600 °C and time between 1 and 48 h in air atmosphere. Based on the microstructure evolution of the oxide layer, the mechanisms and kinetics of the oxidation process were proposed. The existence of silicon oxycarbides (SiOxCy) at the SiO2/SiC interface was demonstrated by X-ray photospectroscopy (XPS) analysis. Carbon was detected by Raman spectroscopy at the interface under conditions of very high temperatures and long oxidation time. From oxidation kinetics calculation, activation energies were 145 kJ/mol and 352 kJ/mol for the temperature ranges of 1200–1500 °C and 1550–1600 °C, respectively.

Generation IV high temperature gas-cooled reactors (HTGR) are preferentially fueled by spherical fuel elements, which are composed of a fuel zone of triso-coated uranium oxide (UO 2 ) particles and a matrix graphite layer. Unqualified coated particles and spherical fuel elements unavoidablely occur during the processing of coating UO 2 kernels and embedding the coated particles into the graphite matrix. So it is necessary to reprocess the UO 2 in the unqualified coated particles and spherical fuel elements to maximize the use of the reactor core materials. In this work, we present several methods to: (1) separate the coated particles from the graphite matrix and, (2) expose and recover the UO 2 kernels from the coated particles. The comparison of different methods shows that the thermal oxidation of graphite by a fixed bed burner and the jet grinding of the unqualified coated particles are prosing in practice for the separation of coated particles from the graphite matrix and recovering the uranium dioxide kernels, respectively. Some other methods, such as etching the SiC layer with the active fluorine species in plasma generated by the dielectric barrier discharge (DBD) under the atmosphere also show their great potential values in the reprocessing of reactor core materials, especially for the activated and contaminated fuels.

The 3-d Euler–Euler CFD simulation was adopted to study the particle dynamics in the spouted bed under different operation conditions and different gas inlet structures (traditional single-nozzle inlet, modified single-nozzle inlet, multi-nozzle inlet and swirl flow design inlet). The maximum spouted height is mainly determined by the gas velocity. The simulation results were in good agreement with the experimental results in spouted bed with traditional single-nozzle inlet. The gas velocity increase will also reduce the volume of particle clusters in spouted bed with multi-nozzle inlet. By comparing simulation results, the multi-nozzle inlet and special swirl flow design inlet is better than single nozzle inlet for obtaining a more uniform fluidization state, which can disperse the gas to increase the gas–particle contact efficiency. The specially swirl flow design can reduce the accumulation of solid particles close to the wall further, especially at the bottom of the spouted bed. The experimental study should be given to validate the superiority of this newly swirl flow design inlet before the industrial application in the future.

Primary biliary cholangitis (PBC) is an autoimmune liver disease with a strong hereditary component. Here, we report a genome-wide association study that included 1,122 PBC cases and 4,036 controls of Han Chinese descent, with subsequent replication in a separate cohort of 907 PBC cases and 2,127 controls. Our results show genome-wide association of 14 PBC risk loci including previously identified 6p21 (HLA-DRA and DPB1), 17q12 (ORMDL3), 3q13.33 (CD80), 2q32.3 (STAT1/STAT4), 3q25.33 (IL12A), 4q24 (NF-κB) and 22q13.1 (RPL3/SYNGR1). We also identified variants in IL21, IL21R, CD28/CTLA4/ICOS, CD58, ARID3A and IL16 as novel PBC risk loci. These new findings and histochemical studies showing enhanced expression of IL21 and IL21R in PBC livers (particularly in the hepatic portal tracks) support a disease mechanism in which the deregulation of the IL21 signalling pathway, in addition to CD4 T-cell activation and T-cell co-stimulation are critical components in the development of PBC., Primary biliary cholangitis is an autoimmune liver disease. Here, the authors show that variants in interleukin genes which potentially deregulate their expression are associated with this condition, and suggest that the IL21 signalling pathway may have a role in disease aetiology.

In the present study, a 2D Euler–Euler numerical simulation was carried out to study the hydrodynamics in the spouted bed with different gas velocities and gas inlets (single-nozzle and multi-nozzle). The maximum spouted height could be mainly determined by the gas velocity if the packing heights of particles were the same. The spatial distribution of particles was uneven and the aggregation of them near the wall could be found when using the single-nozzle gas inlet, regardless of the gas velocity. The aggregation of particles could be partly reduced by using the multi-nozzle gas inlet instead. The dead zone could be eliminated under appropriate particle loading by using the spouted bed bottom with the multi-nozzle gas inlet. Based on the simulation results, the appropriate gas distributor design was recommended to increase the gas solid contact efficiency. It can also be revealed that the temperature would affect the physical properties of gas and particles, thus affecting the particle fluidized state from the simulation results. The maximum spouted height increased with increasing temperature, but the quantitative comparison between the simulation results and the experimental ones can not be obtained because of the limitation of the measuring techniques at high temperature. The present investigation showed that the gas distributor had a critical impact on the gas-particle contact efficiency in the gas–solid two-phase system in the spouted bed, and CFD is a good alternative tool to optimize the spouted bed design in researching the coating process of the UO2 kernel.

As the most promising candidate of SiC-coated fuel particles used in HTR fuel element, ZrC-coated particle has excellent irradiation performance. In this paper, ZrC coating is deposited by CVD with ZrCl4 powder supply method. ZrCl4 powder supply equipment and the saturation vapor pressure are studied, which show that saturation vapor pressure of ZrCl4 is enough to satisfy deposition of ZrC coating in fluidized bed. Several deposition parameters such as C/Zr ratio and deposition temperature are investigated theoretically and experimentally, which have influence on ZrC coating key properties, such as mol ratio of Zr/C, and density. The results show that in a given temperature, C/Zr ratio in raw gas has more influence on ZrC structure, and high quality ZrC coating can be deposited by optimal condition with this method.

The pressure signals in the coating furnace are obtained experimentally from the TRISO UO 2 -coated fuel particle fabrication process. The pressure signals during the coating process are analyzed and a simplified relationship about the pressure drop change due to the coated layer is proposed based on the spouted bed hydrodynamics. The change of pressure drop is found to be consistent with the change of the combination factor about particle density, bed density, particle diameter and static bed height, during the successive coating process of the buffer PyC, IPyC, SiC and OPyC layer. The newly proposed relationship is validated by the experimental values. Based on this relationship, a convenient method is proposed for real-time monitoring the fluidized state of the particles in a high-temperature coating process in the spouted bed. It can be found that the pressure signals analysis is an effective method to monitor the fluidized state on-line in the coating process at high temperature up to 1600 °C.

Vapor pressure of zirconium tetrachloride(ZrCl4) under vacuum and an argon pressure of 1×105 Pa was measured. The thermochemical changes of ZrCl4 during evaporation were studied by thermogravimetry-differential thermal analysis(TG-DTA), X-ray diffractometry(XRD), scanning electron microscopy(SEM) and energy-dispersive X-ray(EDX) analysis. At the same temperature, vapor pressures of ZrCl4 under vacuum and an argon pressure of 1×105 Pa are approximately the same. The vapor pressure exceeds 1×105 Pa at 340 °C, which is high enough for ZrC coating of coated fuel particles. ZrCl4 sample is hydrolyzed to some extent to give ZrO2 and HCl, which however, has little influence on vapor pressure of ZrCl4 at high temperature. No ZrCl3 and Cl2 are produced by decomposition of ZrCl4 during evaporation, which is confirmed by thermodynamic calculation.

Compact and uniform zirconium carbide (ZrC) coatings have been successfully deposited on coated fuel particles using a ZrCl4+H2+Ar+C3H6 gas mixture. Zirconium tetrachloride (ZrCl4) powder feeder was especially designed and manufactured to control accurately the flow rate of ZrCl4 and produce ZrC on an industrial scale. The coating has a large density (6.57 g/cm3), a thickness of 35 μm, a stoichiometry close to Zr/C=1, and a clear interface between the coating and substrate. The coating exhibits an fcc-ZrC phase with a grain size of 11.18 nm and a (111) texture coefficient of 0.57, which corresponds to a polycrystalline microstructure of randomly oriented ZrC grains. The preparation apparatus, processing conditions, properties, microstructures, and morphologies of the ZrC coating are investigated systematically.

The R&D of coating process of fuel particles is one of the most important key technologies in the research work of high-temperature gas-cooled reactor (HTGR). A safe and reliable coating process is expected and related to the prospect of large-scale utilization of nuclear energy. The related research of the carbon black powder which is the main byproduct generated in the coating process is important, because it relates to the impact of coating process on the surrounding environment and is also helpful to understand the deposit mechanism of PyC (pyrolytic carbon) layer coated on the fuel particle. In the present study, the microstructure of the pyrolytic carbon powder were systematically investigated by scanning electron microscope (SEM), transmission electron microscopy (TEM), laser Raman spectroscopy and particle size analysis (PSA). It can be found that the carbon powder in the cyclone separator is composed of the nano-spherical particles with the diameter of about 50nm. The ring-layered nano-structured carbon particles could be found from the electron micrographs. The comparison between Raman spectra of carbon powder and pyrolytic carbon coated on the fuel particle showed that the droplet deposit mechanism was suitable to explain the PyC deposition process. The nano-particles agglomerate into the irregular floc and the diameters of the stable particle clusters are mainly 1 μm and 10 μm. The disposal methods of carbon black powder are also discussed.Copyright © 2010 by ASME