Parameter calculation and result storage for phase-field simulation in α-Mg dendrite growth of Mg-5-wt% Zn alloy

Parameter calculation and result storage, as two necessary steps in phase-field simulation play an important role in ensuring the accuracy of simulation results. A strategy of parameter calculation and result storage is presented for phase-field simulation in α-Mg dendrite growth of Mg-5-wt% Zn alloy under isothermal solidification. Based on the phase diagram and empirical formulas, key parameters of the phase-field model, such as equilibrium partition coefficient k, liquidus slope m, solutal diffusion coefficient in liquid Dl, and solutal diffusion coefficient in solid Ds, can be obtained.Both structured grid method and structured point method can be used to store simulation results, but using the latter method will reduce about 60% storage space and 37.5% storage time compared with the former. Finally, convergent simulation results of α-Mg dendrite growth are obtained and they are in good agreement with the experimental results about optical micrograph, which verify the accuracy of parameters and stability of storage method.

Growth and inhibition of zinc anode dendrites in Zn-air batteries:Model and experiment

Zinc(Zn)-air batteries are widely used in secondary battery research owing to their high theoretical energy density,good electrochemical reversibility,stable discharge performance,and low cost of the anode active material Zn.However,the Zn anode also leads to many challenges,including dendrite growth,deformation,and hydrogen precipitation self-corrosion.In this context,Zn dendrite growth has a greater impact on the cycle lives.In this dissertation,a dendrite growth model for a Zn-air battery was established based on electrochemical phase field theory,and the effects of the charging time,anisotropy strength,and electrolyte temperature on the morphology and growth height of Zn dendrites were studied.A series of experiments was designed with different gradient influencing factors in subsequent experiments to verify the theoretical simulations,including elevated electrolyte temperatures,flowing electrolytes,and pulsed charging.The simulation results show that the growth of Zn dendrites is controlled mainly by diffusion and mass transfer processes,whereas the electrolyte temperature,flow rate,and interfacial energy anisotropy intensity are the main factors.The experimental results show that an optimal electrolyte temperature of 343.15 K,an optimal electrolyte flow rate of 40 ml·min^(-1),and an effective pulse charging mode.

Phase-field lattice-Boltzmann study on fully coupled thermal-solute-convection dendrite growth of Al-Cu alloy

Dendrite growth is a complex liquid-solid phase transition process involving multiple physical factors.A phase-field lattice-Boltzmann method was developed to simulate the two-and three-dimension dendrite growth of Al-Cu alloy.The effect of fully coupled thermal-solute-convection interaction on the dendrite growth was investigated by incorporating a parallel-adaptive mesh refinement algorithm into the numerical model.By accurately reproducing the latent heat release,solute diffusion and convective transport behaviors at the liquidsolid interface,the interaction mechanism among thermal-solute-convection transport as well as their coupling effects on the dendrite growth dynamics were discussed.The simulation results show that the release of latent heat slows down the dendrite growth rate,and both natural and forced convection disrupt the symmetrical growth of dendrites.Their combination makes the growth of dendrites more complex,capturing important physical aspects such as recalescence,dendrite tip splitting,dendrite tilting,dendrite remelting,and solute plume in the simulation case.Based on the robustness and powerful ability of the numerical model,the formation mechanisms of these physical aspects were revealed.

Bilayer separator enabling dendrite-free zinc anode with ultralong lifespan >5000 h

Aqueous zinc(Zn)batteries with Zn metal anodes are promising clean energy storage devices with intrinsic safety and low cost.However,Zn dendrite growth severely restricts the use of Zn anodes.To effectively suppress Zn dendrite growth,we propose a bilayer separator consisting of commercial butter paper and glassfiber membrane.The dense cellulose-based butter paper(BP)with low zincophilicity and high mechanical properties prevents the pore-filling behavior of deposited Zn and related separator piercing,effectively suppressing the Zn dendrite growth.As a result,the bilayer separators endow the ZnjjZn symmetrical batteries with a superlong cycling life of Zn anodes(over 5000 h)at 0.5 mA cm^(-2) and the full batteries enhanced capacity retention,demonstrating the advancement of the bilayer separator to afford excellent cyclability of aqueous metal batteries.

Phase-Field Lattice-Boltzmann Study for α-Mg Dendrite Growth of Mg-5wt%Zn Alloy with Forced Convection

Melt flow can significantly change the transport of heat and solute,dendrite growth.In this work,a phase-field lattice-Boltzmann model was developed to studyα-Mg dendrite growth of Mg-5wt%Zn alloy with forced convection.Results show that the existence of forced convection and overlap of thermal and solute fields makes thermal and solute fields distribution nonuniform.Thus,the symmetry of dendrite morphology is destroyed.The solid temperature and concentration of the downstream dendrite tip front with forced convection are higher than that without forced convection,while the concentration of the upstream dendrite tip front is lower.The solute transport through melt flow will be hindered by developed sidebranching.With flow velocity increase,the upstream temperature gradient and thickness of the downstream solute enrichment layer increase gradually,while the downstream temperature gradient and thickness of the upstream solute enrichment layer decrease gradually.Meanwhile,the upstream dendrite tip velocity will increase gradually,while the downstream dendrite tip velocity will decrease at first and then unchanged.This study is helpful to establish the relationship betweenα-Mg dendrite growth and melt flow,which is beneficial to understand the role of melt flow on dendrite morphologies.

血清β2-MG、cys-C、RBP、CRP检测在糖尿病早期肾损伤中的应用

探讨β2-MG、Cys-C、RBP、CRP四项指标在糖尿病肾病患者诊断中的应用效果。方法 将100例糖尿病患者随机分为两组,其中单纯糖尿病患者(DM组)50例,糖尿病合并肾病患者(DN组)50例,另选取50例同期体检健康者作为对照组,分别采集静脉血,测定血清中的β2-MG、Cys-C、RBP、CRP四项指标,分析三组样本四项指标的相关性及各项指标检测的灵敏性和特性性,评价其应用价值。结果 DM组、DN组与健康对照组四项指标检测值均存在显著性差异(P<0.05),四项指标对DN的检测具有不同程度的阳性检出率,β2-MG检测的准确率最高,为88.00%。结论 β2-MG、Cys-C、RBP、CRP四项指标对糖尿病早期肾损伤均具有一定的识别度,对疾病的诊断及治疗方案的制定具有一定的参考价值。

Unveiling the influence of dendrite characteristics on the slip/twinning activity and the strain hardening capacity of Mg-Sn-Li-Zn cast alloys

This work explores the correlation between the characteristics of the cast structure(dendrite growth pattern,dendrite morphology and macro-texture)and strain hardening capacity during high temperature deformation of Mg-5Sn-0.3Li-0 and 3Zn multi-component alloys.The three dimensional(3D)morphology of the dendrite structure demonstrates the transition of the growth directions from<1123>,<1120>and<1122>to<1123>and<1120>due to the addition of Zn.The simultaneous effects of growing tendency and the decrement of dendrite coarsening rate at the solidification interval lead to dendrite morphology transition from the globular-like to the hyper-branch structure.This morphology transition results in the variation of the solidification macro-texture,which has effectively influenced the dominant deformation mechanisms(slip/twin activity).The higher activity of the slip systems increases the tendency of the dendrite arms for bending along the deformation direction and fragmentation.Apart from this,the dendrite holding hyper-branch structure with an average thickness below 20μm are more favorable for fragmentation.The dendrite fragmentation leads to considerable softening fractions,and as an effective strain compensation mechanism increases the workability of dendritic structure.

Simulation of inclined dendrites under natural convection by KKS phase field model based on CUDA

In this work,Al-4.5wt.%Cu was selected as the research object,and a phase field-lattice Boltzmann method(PF-LBM)model based on compute unified device architecture(CUDA)was established to solve the problem of low serial computing efficiency of a traditional CPU and achieve significant acceleration.This model was used to explore the evolution of dendrite growth under natural convection.Through the study of the tip velocities,it is found that the growth of the dendrite arms at the bottom is inhibited while the growth of the dendrite arms at the top is promoted by natural convection.In addition,research on the inclined dendrite under natural convection was conducted.It is observed that there is a deviation between the actual growth direction and the preferred angle of the inclined dendrite.With the increase of the preferred angle of the seed,the difference between the actual growth direction and the initial preferred angle of the inclined dendrite shows a trend of increasing at first and then decreasing.In the simulation area,the relative deflection directions of the primary dendrite arms in the top right corner and the bottom left corner of the same dendrite are almost counterclockwise,while the relative deflection directions of the other two primary dendrite arms are clockwise.

Overdischarge-induced evolution of Cu dendrites and degradation of mechanical properties in lithium-ion batteries

The degradation of mechanical properties of overdischarge battery materials manifests as a significant effect on the energy density,safety,and cycle life of the batteries.However,establishing the correlation between depth of overdischarge and mechanical properties is still a significant challenge.Studying the correlation between depth of overdischarge and mechanical properties is of great significance to improving the energy density and the ability to resist abuse of the batteries.In this paper,the mechanical properties of the battery materials during the whole process of overdischarge from discharge to complete failure were studied.The effects of depth of overdischarge on the elastic modulus and hardness of the cathode of the battery,the tensile strength and the thermal shrinkage rate of the separator,and the performance of binder were investigated.The precipitation of Cu dendrites on the separator and cathode after dissolution of anode copper foil is a key factor affecting the performance of battery materials.The Cu dendrites attached to the cathode penetrate the separator,causing irreversible damage to the coating and base film of the separator,which leads to a sharp decline in the tensile strength,thermal shrinkage rate and other properties of the separator.In addition,the Cu dendrites wrapping the cathode active particles reduce the adhesion of the active particles binder.Meanwhile,the active particles are damaged,resulting in a significant decrease in the elastic modulus and hardness of the cathode.

Effect of traveling-wave magnetic field on dendrite growth of high-strength steel slab: Industrial trials and numerical simulation

The dendrite growth behavior of high-strength steel during slab continuous casting with a traveling-wave magnetic field was studied in this paper. The morphology of the solidification structure and composition distribution were analyzed. Results showed that the columnar crystals could deflect and break when the traveling-wave magnetic field had low current intensity. With the increase in current intensity, the secondary dendrite arm spacing and solute permeability decreased, and the columnar crystal transformed into an equiaxed crystal. The electromagnetic force caused by the traveling-wave magnetic field changed the temperature gradient and velocity magnitude and promoted the breaking and fusing of dendrites. Dendrite compactness and composition uniformity were arranged in descending order as follows:columnar-toequiaxed transition (high current intensity), columnar crystal zone (low current intensity), columnar-to-equiaxed transition (low current intensity), and equiaxed crystal zone (high current intensity). Verified numerical simulation results combined with the boundary layer theory of solidification front and dendrite breaking–fusing model revealed the dendrite deflection mechanism and growth process. When thermal stress is not considered, and no narrow segment can be found in the dendrite, the velocity magnitude on the solidification front of liquid steel can reach up to 0.041 m/s before the dendrites break.

Chemical surface tuning of zinc metal anode toward stable,dendrite-less aqueous zinc-ion batteries

The commercialization of Zn batteries is confronted with urgent challenges in the metal anode,such as dendrite formation,capacity loss,and cracking or dissolution.Here,surface interfacial engineering of the Zn anode is introduced for achieving safety and dendritic-free cycling for high-performance aqueous Zn batteries through a simple but highly effective chemical etching-substitution method.The chemical modification induces a rough peak-valley surface with a thin fluorine-rich interfacial layer on the Zn anode surface,which regulates the growth orientation via guiding uniform Zn plating/stripping,significantly enhances accessibility to aqueous electrolytes and improves wettability by reducing surface energy.As a result,such a synergetic surface effect enables uniform Zn plating/stripping with low polarization of 29 m V at a current density of 0.5 m A cm^(-2) with stable cyclic performance up to 1000 h.Further,a full cell composed of a fluorine-substituted Zn anode coupled with aβ-MnO_(2)or Ba-V_(6)O_(13)cathode demonstrates improved capacity retention to 1000 cycles compared to the pristine-Zn cells.The proposed valley deposition model provides the practical direction of surface-modified interfacial chemistries for improving the electrochemical properties of multivalent metal anodes via surface tuning.

The mechanism of external pressure suppressing dendrites growth in Li metal batteries

Li metal is considered an ideal anode material for application in the next-generation secondary batteries.However,the commercial application of Li metal batteries has not yet been achieved due to the safety concern caused by Li dendrites growth.Despite the fact that many recent experimental studies found that external pressure suppresses the Li dendrites growth,the mechanism of the external pressure effect on Li dendrites remains poorly understood on the atomic scale.Herein,the large-scale molecular dynamics simulations of Li dendrites growth under different external pressure were performed with a machine learning potential,which has the quantum-mechanical accuracy.The simulation results reveal that the external pressure promotes the process of Li self-healing.With the increase of external pressure,the hole defects and Li dendrites would gradually fuse and disappear.This work provides a new perspective for understanding the mechanism for the impact of external pressure on Li dendrites.

Elucidating the suppression of lithium dendrite growth with a void-reduced anti-perovskite solid-state electrolyte pellet for stable lithium metal anodes

Solid-state lithium-metal batteries,with their high theoretical energy density and safety,are highly promising as a next-generation battery contender.Among the alternatives proposed as solid-state electrolyte,lithium-rich anti-perovskite(Li RAP)materials have drawn the most interest because of high theoretical Li^(+)conductivity,low cost and easy processing.Although solid-state electrolytes are believed to have the potential to physically inhibit the lithium dendrite growth,lithium-metal batteries still suffer from the lithium dendrite growth and thereafter the short circuiting.The voids in practical Li RAP pellets are considered as the root cause.Herein,we show that reducing the voids can effectively suppress the lithium dendrite growth.The voids in the pellet resulted in an irregular Li^(+)flux distribution and a poor interfacial contact with lithium metal anode;and hence the ununiform lithium dendrites.Consequently,the lithium-metal symmetric cell with void-reduced Li_(2)OHCl-HT pellet was able to display excellent cycling performance(750 h at 0.4 m A cm^(-2))and stability at high current density(0.8 m A cm^(-2)for 120 h).This study provides not only experimental evidence for the impact of the voids in Li RAP pellets on the lithium dendrite growth,but also a rational pellet fabrication approach to suppress the lithium dendrite growth.

Motor neuron-specific RhoA knockout delays degeneration and promotes regeneration of dendrites in spinal ventral horn after brachial plexus injury

Dendrites play irreplaceable roles in the nerve conduction pathway and are vulnerable to various insults.Peripheral axotomy of motor neurons results in the retraction of dendritic arbors,and the dendritic arbor can be re-expanded when reinnervation is allowed.RhoA is a target that regulates the cytoskeleton and promotes neuronal survival and axon regeneration.However,the role of RhoA in dendrite degeneration and regeneration is unknown.In this study,we explored the potential role of RhoA in dendrites.A line of motor neuronal conditional knockout mice was developed by crossbreeding HB9~(Cre+)mice with RhoA~(flox/flox)mice.We established two models for assaying dendrite degeneration and regeneration,in which the brachial plexus was transection or crush injured,respectively.We found that at 28 days after brachial plexus transection,the density,complexity,and structural integrity of dendrites in the ventral horn of the spinal cord of RhoA conditional knockout mice were slightly decreased compared with that in Cre mice.Dendrites underwent degeneration at 7 and 14 days after brachial plexus transection and recovered at 28–56 days.The density,complexity,and structural integrity of dendrites in the ventral horn of the spinal cord of RhoA conditional knockout mice recovered compared with results in Cre mice.These findings suggest that RhoA knockout in motor neurons attenuates dendrite degeneration and promotes dendrite regeneration after peripheral nerve injury.

血清CEA、CA19-9、β_(2)-MG表达与膀胱癌患者吡柔比星膀胱灌注化疗疗效和生存期相关分析

目的探讨膀胱癌患者血清癌胚抗原(CEA)、癌抗原199(CA19-9)、β_(2)微球蛋白(β_(2)-MG)水平与膀胱癌患者吡柔比星膀胱灌注化疗疗效和生存期的关系。方法选取2021年3月~2023年4月在南阳市第一人民医院接受吡柔比星膀胱灌注化疗的98例膀胱癌患者作为研究对象,根据化疗结果分为化疗有效组(52例)和化疗无效组(46例)。比较两组患者的临床资料和血清CEA、CA19-9、β_(2)-MG水平,并进行单因素和多因素分析、生存分析及Cox回归分析。结果化疗有效组血清CEA、CA19-9、β_(2)-MG水平均低于化疗无效组(P<0.001)。进一步经多因素Logistic回归分析显示血清CEA水平是影响化疗效果和生存期的独立危险因素,高表达者化疗效果差,预后不良。血清CA19-9、β_(2)-MG水平也与化疗效果相关,但不是独立影响因素。结论血清CEA水平是预测膀胱灌注化疗疗效和生存期的重要指标,建议对膀胱癌患者进行血清CEA、CA19-9、β_(2)-MG检测,以指导个体化治疗方案的制定。

不同血液净化方式对血液透析患者β2-MG、SCr、PTH水平的影响

分析不同血液净化方法对患者血清β2微球蛋白、SC肌酐、甲状旁腺激素水平的影响。方法 将85名尿毒症患者按照随机数表法分为HD组(血液透析)、HDF(血液透析滤过)+HD组、HD+HP(血液灌流)组,三组均接受3个月的治疗疗程。比较三组Scr、BUN(尿素氮)、β2 -MG、PTH水平。结果 治疗后三组患者上述指标均优于治疗前,生活质量评分均显著提高(P<0.05)。与HD组相比,HD+HP组和HD+HDF组均高于HD组(P<0.05)结论 三种方法对于尿毒症患者均可以起到良好的透析效果,相较于单一的HD法,HD+HDF、HD+HP能够更好的清除毒素与改善患者生活质量。

Relationship between Phenotypic Changes of Dendritic Cell Subsets and the Onset of Plateau Phase during Intermittent Interferon Therapy in Patients with CHB

Objective This study aimed to evaluate whether the onset of the plateau phase of slow hepatitis B surface antigen decline in patients with chronic hepatitis B treated with intermittent interferon therapy is related to the frequency of dendritic cell subsets and expression of the costimulatory molecules CD40,CD80,CD83,and CD86.Method This was a cross-sectional study in which patients were divided into a natural history group(namely NH group),a long-term oral nucleoside analogs treatment group(namely NA group),and a plateau-arriving group(namely P group).The percentage of plasmacytoid dendritic cell and myeloid dendritic cell subsets in peripheral blood lymphocytes and monocytes and the mean fluorescence intensity of their surface costimulatory molecules were detected using a flow cytometer.Results In total,143 patients were enrolled(NH group,n=49;NA group,n=47;P group,n=47).The results demonstrated that CD141/CD1c double negative myeloid dendritic cell(DNmDC)/lymphocytes and monocytes(%)in P group(0.041[0.024,0.069])was significantly lower than that in NH group(0.270[0.135,0.407])and NA group(0.273[0.150,0.443]),and CD86 mean fluorescence intensity of DNmDCs in P group(1832.0[1484.0,2793.0])was significantly lower than that in NH group(4316.0[2958.0,5169.0])and NA group(3299.0[2534.0,4371.0]),Adjusted P all<0.001.Conclusion Reduced DNmDCs and impaired maturation may be associated with the onset of the plateau phase during intermittent interferon therapy in patients with chronic hepatitis B.

PCDH17 restricts dendritic spine morphogenesis by regulating ROCK2-dependent control of the actin cytoskeleton,modulating emotional behavior

Proper regulation of synapse formation and elimination is critical for establishing mature neuronal circuits and maintaining brain function.Synaptic abnormalities,such as defects in the density and morphology of postsynaptic dendritic spines,underlie the pathology of various neuropsychiatric disorders.Protocadherin 17(PCDH17)is associated with major mood disorders,including bipolar disorder and depression.However,the molecular mechanisms by which PCDH17 regulates spine number,morphology,and behavior remain elusive.In this study,we found that PCDH17 functions at postsynaptic sites,restricting the number and size of dendritic spines in excitatory neurons.Selective overexpression of PCDH17 in the ventral hippocampal CA1 results in spine loss and anxiety-and depression-like behaviors in mice.Mechanistically,PCDH17 interacts with actin-relevant proteins and regulates actin filament(F-actin)organization.Specifically,PCDH17 binds to ROCK2,increasing its expression and subsequently enhancing the activity of downstream targets such as LIMK1 and the phosphorylation of cofilin serine-3(Ser3).Inhibition of ROCK2 activity with belumosudil(KD025)ameliorates the defective F-actin organization and spine structure induced by PCDH17 overexpression,suggesting that ROCK2 mediates the effects of PCDH17 on F-actin content and spine development.Hence,these findings reveal a novel mechanism by which PCDH17 regulates synapse development and behavior,providing pathological insights into the neurobiological basis of mood disorders.

Coexisting fast–slow dendritic traveling waves in a 3D-array electric field coupled neuronal network

Coexistence of fast and slow traveling waves without synaptic transmission has been found in hhhippocampal tissues,which is closely related to both normal brain activity and abnormal neural activity such as epileptic discharge. However, the propagation mechanism behind this coexistence phenomenon remains unclear. In this paper, a three-dimensional electric field coupled hippocampal neural network is established to investigate generation of coexisting spontaneous fast and slow traveling waves. This model captures two types of dendritic traveling waves propagating in both transverse and longitude directions: the N-methyl-D-aspartate(NMDA)-dependent wave with a speed of about 0.1 m/s and the Ca-dependent wave with a speed of about 0.009 m/s. These traveling waves are synaptic-independent and could be conducted only by the electric fields generated by neighboring neurons, which are basically consistent with the in vitro data measured experiments. It is also found that the slow Ca wave could trigger generation of fast NMDA waves in the propagation path of slow waves whereas fast NMDA waves cannot affect the propagation of slow Ca waves. These results suggest that dendritic Ca waves could acted as the source of the coexistence fast and slow waves. Furthermore, we also confirm the impact of cellular spacing heterogeneity on the onset of coexisting fast and slow waves. The local region with decreasing distances among neighbor neurons is more liable to promote the onset of spontaneous slow waves which, as sources, excite propagation of fast waves. These modeling studies provide possible biophysical mechanisms underlying the neural dynamics of spontaneous traveling waves in brain tissues.

Suppressing dendritic metallic Li formation on graphite anode under battery fast charging

Lithium-ion batteries(LIBs)with fast-charging capability are essential for enhancing consumer experience and accelerating the global market adoption of electric vehicles.However,achieving fast-charging capability without compromising energy density,cycling lifespan,and safety of LIBs remains a significant challenge due to the formation of dendritic Li metal on graphite anode under fast charging condition.In view of this,the fundamentals for the dendritic metallic Li formation and the strategies for suppressing metallic Li plating based on analyzing the entire Li^(+)transport pathway at the anode including electrolyte,pore structure of electrode,and surface and bulk of materials are summarized and discussed in this review.Besides,we highlight the importance of designing thick electrodes with fast Li^(+)transport kinetics and comprehensively understanding the interaction between solid electrolyte interphase(SEI)and Li^(+)migration in order to avoid the formation of dendritic Li metal in practical fast-charging batteries.Finally,the regulation of Li metal plating with plane morphology,instead of dendritic structure,on the surface of graphite electrode under fast-charging condition is analyzed as a future direction to achieve higher energy density of batteries without safety concerns.