Microstructure,Corrosion and Mechanical Properties of Medium-Thick 6061-T6 Alloy/T2 Pure Cu Dissimilar Joints Produced by Double Side Friction Stir Z Shape Lap-Butt Welding

A novel double side friction stir Z shape lap-butt welding(DS-FSZW)process was proposed to achieve excellent mechanical properties of Al/Cu medium-thick dissimilar joints.The influence of welding parameters on weld microstructure and properties of DS-FSZW joint were systematically investigated.It indicated that defect-free medium-thick Al/Cu DS-FSZW joint could be achieved under an optimal welding parameter.DS-FSZW joint was prone to form void defects in the bottom of the second-pass weld.The recrystallization mechanisms at the top and middle of the weld nugget zone(WNZ)were continuous dynamic recrystallization(CDRX)and geometric dynamic recrystallization(GDRX).While the major recrystallization mechanism at the bottom of the WNZ was GDRX.DS-FSZW joint of the optimal welding condition with 850 r/min-400 mm/min was produced with a continuous thin and crack-free IMCs layer at the Al/Cu interface,and the maximum tensile strength of this joint is 160.57 MPa,which is equivalent to 65.54%of pure Cu base material.Moreover,the corrosion resistance of Al/Cu DS-FSZW joints also achieved its maximum value at the optimal welding parameter of 850 r/min-400 mm/min.It demonstrates that the DS-FSZW process can simultaneously produce medium-thick Al/Cu joints with excellent mechanical performance and corrosion resistance.

Cu掺杂及缺陷共存对ZnO光催化影响的理论研究

采用密度泛函理论研究了Cu掺杂及缺陷共存对ZnO光催化性能的影响.计算时考虑了富O和贫O两种掺杂条件.研究结果表明富O条件有利于Cu的掺杂,贫O条件则产生抑制作用.当Cu掺杂浓度较低时,不论在何种掺杂条件下,Cu的主要掺杂方式均为Cu_(Zn)型.当Cu掺杂浓度较高时,富O条件下以Cu_(Zn)-Cu_(Zn)型掺杂方式为主,贫O条件下Cu_(Zn)-Cu_(Zn)和Cu_(Zn)-Cui这两种掺杂方式都有可能出现.富O条件下Cu掺杂会促进V_(Zn)和O_(i)缺陷的产生,且引入的V_(Zn)和O_(i)缺陷趋向于距离Cu原子最近.Cu掺杂可有效降低ZnO的带隙宽度,且随着掺杂浓度的增加,相应模型的带隙宽度会继续降低.V_(Zn)、O_(i)和V_(O)缺陷共存使相应模型的带隙宽度有所增加.Cu掺杂及V_(Zn)、O_(i)、V_(O)缺陷共存使模型对可见光发生响应,扩展了模型对太阳光的吸收范围.对于Cu掺杂模型,富O条件下Cu_(Zn)-Cu_(Zn)是有利的光催化模型.对于缺陷共存模型,富O条件下Cu_(Zn)-Cu_(Zn)-V_(Zn)是有利的光催化模型,其次是Cu_(Zn)-V_(Zn)和Cu_(Zn)-O_(i),贫O条件下Cu_(Zn)-V_(O)是有利的光催化模型.

Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite

The damage of rock joints or fractures upon shear includes the surface damage occurring at the contact asperities and the damage beneath the shear surface within the host rock.The latter is commonly known as off-fault damage and has been much less investigated than the surface damage.The main contribution of this study is to compare the results of direct shear tests conducted on saw-cut planar joints and tension-induced rough granite joints under normal stresses ranging from 1 MPa to 50 MPa.The shear-induced off-fault damages are quantified and compared with the optical microscope observation.Our results clearly show that the planar joints slip stably under all the normal stresses except under 50 MPa,where some local fractures and regular stick-slip occur towards the end of the test.Both post-peak stress drop and stick-slip occur for all the rough joints.The residual shear strength envelopes for the rough joints and the peak shear strength envelope for the planar joints almost overlap.The root mean square(RMS)of asperity height for the rough joints decreases while it increases for the planar joint after shear,and a larger normal stress usually leads to a more significant decrease or increase in RMS.Besides,the extent of off-fault damage(or damage zone)increases with normal stress for both planar and rough joints,and it is restricted to a very thin layer with limited micro-cracks beneath the planar joint surface.In comparison,the thickness of the damage zone for the rough joints is about an order of magnitude larger than that of the planar joints,and the coalesced micro-cracks are generally inclined to the shear direction with acute angles.The findings obtained in this study contribute to a better understanding on the frictional behavior and damage characteristics of rock joints or fractures with different roughness.

Optimizing profile line interval for enhanced accuracy in rock joint morphology and shear strength assessments

2D profile lines play a critical role in cost-effectively evaluating rock joint properties and shear strength.However, the interval(ΔI_(L)) between these lines significantly impacts roughness and shear strength assessments. A detailed study of 45 joint samples using four statistical measures across 500 different ΔI_(L)values identified a clear line interval effect with two stages: stable and fluctuation-discrete.Further statistical analysis showed a linear relationship between the error bounds of four parameters,shear strength evaluation, and their corresponding maximum ΔI_(L)values, where the gradient k of this linear relationship was influenced by the basic friction angle and normal stress. Accounting for these factors,lower-limit linear models were employed to determine the optimal ΔI_(L)values that met error tolerances(1%–10%) for all metrics and shear strength. The study also explored the consistent size effect on joints regardless of ΔI_(L)changes, revealing three types of size effects based on morphological heterogeneity.Notably, larger joints required generally higher ΔI_(L)to maintain the predefined error limits, suggesting an increased interval for large joint analyses. Consequently, this research provides a basis for determining the optimal ΔI_(L), improving accuracy in 2D profile line assessments of joint characteristics.

Novel Assessment Technique: Ring Gauge Measurement of Finger Joint Circumference Changes in Patients with Rheumatoid Arthritis

Objectives: As therapeutic modalities for rheumatoid arthritis (RA) advance, immediate and quantitative determination of RA disease status is becoming increasingly important. The purpose of this study was to validate the usefulness of a ring gauge as a simple semiquantitative method for assessing hand swelling in patients with RA. Methods: We enrolled patients diagnosed with RA either initiated or switched to a biological therapeutic agent. The circumference of the interphalangeal (IP) joint and the proximal interphalangeal (PIP) joint was measured using a ring gauge. Assessments of the joint echocardiography, incorporating both Gray Scale (GS) and Power Doppler (PD) imaging, were conducted. These evaluations were performed both before the initiation of biological agent treatment and 28 days after the initial dose. Results: Following the treatment intervention, a significant reduction was observed in the circumference of the joint from the thumb to the little finger (p Conclusions: Our study demonstrated the effectiveness of using a ring gauge as a simple assessment tool for RA, revealing that a change in the ring gauge number by 2 or more corresponded to either improvement or deterioration in synovial thickening detected via joint echocardiography.

Ipsilateral Rockwood type V acromioclavicular joint dislocation and midshaft clavicle fracture:A case report

BACKGROUND Clavicle fractures are among the most common fractures seen in the emergency department.While acromioclavicular(AC)joint injuries are much less common.However,ipsilateral combinations of these injuries are quite rare with only a few cases reported in the literature.CASE SUMMARY A 29-year-old man who sustained a combination of ipsilateral AC joint dislocation and midshaft clavicle fracture.He underwent open reduction and plate fixation of the clavicle fracture,as well as semi-rigid surgical implants used to restore both the AC ligaments and the coracoclavicular joint.one year follow-up revealed that the patient had a complete range of motion and excellent shoulder scores.This case presents a rare presentation of such combination of injuries,contributing valuable insights to the literature on such rare injuries.CONCLUSION Combined midshaft clavicle fractures and AC joint dislocations are considered quite rare.Timely diagnosis of such injuries leads to great functional outcomes.AC joint dislocation should be suspected with midshaft clavicle fractures and should be investigated radiologically and clinically in an appropriate manner.Still,there is no consensus on the optimal management of such injuries.

The joint Laplace transforms for killed diffusion occupation times

The approach of Li and Zhou(2014)is adopted to find the Laplace transform of occupation time over interval(0,a)and joint occupation times over semi-infinite intervals(-∞,a)and(b,∞)for a time-homogeneous diffusion process up to an independent exponential time e_(q)for 0<a<b.The results are expressed in terms of solutions to the differential equations associated with the diffusion generator.Applying these results,we obtain explicit expressions on the Laplace transform of occupation time and joint occupation time for Brownian motion with drift.

Clinical study on improving the diagnostic accuracy of adult elbow joint cartilage injury by multisequence magnetic resonance imaging

BACKGROUND Due to frequent and high-risk sports activities,the elbow joint is susceptible to injury,especially to cartilage tissue,which can cause pain,limited movement and even loss of joint function.AIM To evaluate magnetic resonance imaging(MRI)multisequence imaging for improving the diagnostic accuracy of adult elbow cartilage injury.METHODS A total of 60 patients diagnosed with elbow cartilage injury in our hospital from January 2020 to December 2021 were enrolled in this retrospective study.We analyzed the accuracy of conventional MRI sequences(T1-weighted imaging,T2-weighted imaging,proton density weighted imaging,and T2 star weighted image)and Three-Dimensional Coronary Imaging by Spiral Scanning(3D-CISS)in the diagnosis of elbow cartilage injury.Arthroscopy was used as the gold standard to evaluate the diagnostic effect of single and combination sequences in different injury degrees and the consistency with arthroscopy.RESULTS The diagnostic accuracy of 3D-CISS sequence was 89.34%±4.98%,the sensitivity was 90%,and the specificity was 88.33%,which showed the best performance among all sequences(P<0.05).The combined application of the whole sequence had the highest accuracy in all sequence combinations,the accuracy of mild injury was 91.30%,the accuracy of moderate injury was 96.15%,and the accuracy of severe injury was 93.33%(P<0.05).Compared with arthroscopy,the combination of all MRI sequences had the highest consistency of 91.67%,and the kappa value reached 0.890(P<0.001).CONCLUSION Combination of 3D-CISS and each sequence had significant advantages in improving MRI diagnostic accuracy of elbow cartilage injuries in adults.Multisequence MRI is recommended to ensure the best diagnosis and treatment.

Geometries and electronic structures of Zr_(n)Cu(n=2–12) clusters: A joint machine-learning potential density functional theory investigation

Zr-based amorphous alloys have attracted extensive attention because of their large glassy formation ability, wide supercooled liquid region, high elasticity, and unique mechanical strength induced by their icosahedral local structures.To determine the microstructures of Zr–Cu clusters, the stable and metastable geometry of Zr_(n)Cu(n=2–12) clusters are screened out via the CALYPSO method using machine-learning potentials, and then the electronic structures are investigated using density functional theory. The results show that the Zr_(n)Cu(n ≥ 3) clusters possess three-dimensional geometries, Zr_(n)Cu(n≥9) possess cage-like geometries, and the Zr_(12)Cu cluster has icosahedral geometry. The binding energy per atom gradually gets enlarged with the increase in the size of the clusters, and Zr_(n)Cu(n=5,7,9,12) have relatively better stability than their neighbors. The magnetic moment of most Zr_(n)Cu clusters is just 1μB, and the main components of the highest occupied molecular orbitals(HOMOs) in the Zr_(12)Cu cluster come from the Zr-d state. There are hardly any localized two-center bonds, and there are about 20 σ-type delocalized three-center bonds.

Glutamatergic CYLD deletion leads to aberrant excitatory activity in the basolateral amygdala:association with enhanced cued fear expression

Neuronal activity,synaptic transmission,and molecular changes in the basolateral amygdala play critical roles in fear memory.Cylindromatosis(CYLD)is a deubiquitinase that negatively regulates the nuclear factor kappa-B pathway.CYLD is well studied in non-neuronal cells,yet underinvestigated in the brain,where it is highly expressed.Emerging studies have shown involvement of CYLD in the remodeling of glutamatergic synapses,neuroinflammation,fear memory,and anxiety-and autism-like behaviors.However,the precise role of CYLD in glutamatergic neurons is largely unknown.Here,we first proposed involvement of CYLD in cued fear expression.We next constructed transgenic model mice with specific deletion of Cyld from glutamatergic neurons.Our results show that glutamatergic CYLD deficiency exaggerated the expression of cued fear in only male mice.Further,loss of CYLD in glutamatergic neurons resulted in enhanced neuronal activation,impaired excitatory synaptic transmission,and altered levels of glutamate receptors accompanied by over-activation of microglia in the basolateral amygdala of male mice.Altogether,our study suggests a critical role of glutamatergic CYLD in maintaining normal neuronal,synaptic,and microglial activation.This may contribute,at least in part,to cued fear expression.

Cu-Fe合金凝固过程中结构变化研究

采用分子动力学模拟方法研究了Cu_(100-X)Fe_(X)(X=1%、3%、5%)合金在冷却速率为2×10^(10)K/s条件下合金凝固过程.研究表明,Fe含量为1%时,随着合金温度的降低Fe原子始终保持均匀分布的状态,未出现Fe原子聚集现象,晶体结构是以FCC为主的Cu基体,Fe原子以固溶形式存在于基体中.Fe含量为3%时,随着合金温度的降低Fe原子有聚集趋势,但BCC晶体结构占比较小,晶体结构仍是以FCC为主的Cu基体.Fe含量为5%,随着合金温度的降低Fe原子发生明显聚集,最终形成以FCC、HCP晶体类型为主镶嵌Fe原子的Cu基体.研究了Fe团簇的形成过程,结果表明,Fe团簇的形成、长大是一个连续的过程,该过程受形核生长机制控制,不同阶段形成Fe团簇的大小和数量受Fe-Fe原子相互作用力、Fe原子的扩散能力以及Fe团簇与Cu基体间的界面能三个因素共同影响.

Microstructure and properties of Cu/Al joints brazed with Zn-Al filler metals

The mechanical properties and microstructural distribution of the Cu/A1 brazing joints formed by torch-brazing with different Zn-A1 filler metals were investigated. The microstructure of the Zn-A1 alloys was studied by optical microscopy and scanning electron microscopy, and the phase constitution of the Cu/A1 joints was analyzed by energy dispersion spectrometry. The results show that the spreading area of the Zn-A1 filler metals on the Cu and A1 substrates increases as the A1 content increases. The mechanical results indicate that the shear strength reaches a peak value of 88 MPa when A1 and Cu are brazed with Zn-15AI filler metal. Microhardness levels from HV122 to HV515 were produced in the three brazing seam regions corresponding to various microstructure features. The Zn- and Al-rich phases exist in the middle brazing seam regions. However, two interface layers, CuZn3 and A12Cu are formed on the Cu side when the A1 content in the filler metals is 2% and more than 15%, respectively. The relationship between intermetallic compounds on Cu side and Zn-xA1 filler metals was investigated.

Drop failure modes of Sn-3.0Ag-0.5Cu solder joints in wafer level chip scale package

To reveal the drop failure modes of the wafer level chip scale packages （WLCSPs） with Sn-3.0Ag-0.5Cu solder joints, board level drop tests were performed according to the JEDEC standard. Six failure modes were identified, i.e., short FR-4 cracks and complete FR-4 cracks at the printing circuit board （PCB） side, split between redistribution layer （RDL） and Cu under bump metallization （UBM）, RDL fracture, bulk cracks and partial bulk and intermetallic compound （IMC） cracks at the chip side. For the outmost solder joints, complete FR-4 cracks tended to occur, due to large deformation of PCB and low strength of FR-4 dielectric layer. The formation of complete FR-4 cracks largely absorbed the impact energy, resulting in the absence of other failure modes. For the inner solder joints, the absorption of impact energy by the short FR-4 cracks was limited, resulting in other failure modes at the chip side.

Influence of electron-beam superposition welding on intermetallic layer of Cu/Ti joint

QCr0.8 was electron-beam welded to TC4 and the effect of the intermetallic layer （IMC-layer） on the mechanical properties of the joint was investigated. The IMC-layers are joint weaknesses at the Cu fusion line in centered welding and at the Ti fusion line when the beam is deviated towards Cu. A new method referred to as electron-beam superposition welding was presented, and the optimal welding sequence was considered. The IMC-layer produced by centered welding was fragmented and remelted during Cu-side non-centered welding, giving a finely structured compound layer and improved mechanical properties of the joint. The tensile strength of joint is 276.0 MPa, 76.7% that of the base metal.

Effect of temperature on interface diffusion in micro solder joint under current stressing

The effects of temperature on Cu pad consumption and intermetallic compound（IMC） growth were investigated under current stressing. The Cu/Sn-3.0Ag-0.5Cu（SAC305）/Cu solder joints were used, with a certain current density of 0.76×104A/cm^2 at 100, 140, 160 and 180 °C. The constitutive equations of cathode Cu pad consumption and anode interface IMC growth are established, respectively, based on the loading time and sample temperature. The cathode Cu pad consumption（δ） increases linearly with the loading time and the consumption rate shows parabolic curve relationships with sample temperature. The anode interface IMC thickness（δ1） increased is linearly with the square root of loading time and the interface IMC growth coefficient shows parabolic curve relationship with sample temperature. The δ and δ1 have different variation laws under current stressing, due to the current facilitating larger amount of IMC formation in the bulk solder.

Strength calculation methodology for internally ring- stiffened DT- joints

In order to obtain the strength design equations for internally ring-stiffened circular hollowsection tubular DT（ double tee）-joints subjected to brace axial compression or tension, theoretical and numerical studies on 800 stiffened joints were conducted. Based on the failure mechanism of the stiffened joints, four theoretical models and corresponding equations for predicting the strength of the stiffeners are proposed. Combined with existing unstiffened DT-joint design equations, a design equation for the stiffened joints is proposed. The finite element analysis shows that the failure of the stiffened joints under brace axial loads can be characterized by plastic hinges forming in the stiffener and chord wall yielding in the vicinity of the brace-chord intersection. The reliability of the proposed stiffener strength equations is demonstrated by a reliability analysis. Good agreement is achieved between the stiffened joint strength calculated from the proposed joint strength equation and that obtained from finite element analysis.

Cu/Ce负载对赤泥脱除中低温烟气中NO的促进作用

本研究对酸洗赤泥催化剂进行Cu、Ce、Cu/Ce浸渍负载,并研究了金属改性赤泥对烟气中NOx的催化转化性能。研究结果表明,Cu负载催化剂中的Cu+与Cu^(2+),有效促进了赤泥对低温烟气(200–300℃)中的NO转化率,Cu的负载量达到6%时,赤泥的最高NO转化率达到了90.7%;而Ce负载催化剂中的Ce^(3+)与Ce^(4+),有效促进了赤泥对中温烟气(200–400℃)中的NO转化率,Ce的负载量达到8%时,赤泥的最高NO转化率达到了94.0%;Cu/Ce负载催化剂表现出比单金属负载催化剂更好的低温NO转化率,最佳的负载Cu:Ce比例为1∶1,双金属负载催化剂表现出比Cu负载催化剂更好的中温(300–400℃)中的NO转化率,最高达到了95.5%。其原因是,在Cu/Ce协同作用下,Cu+以及Cu^(2+)的还原过程分别从229、302℃降至201以及247℃,同时使发生Fe2O3→FeO的还原过程的温度降低,促使ACRM-Cu1Ce1具有更强的低温氧化还原能力,同时,双金属负载使催化剂具有更高的弱酸性峰,也使催化剂的强、弱酸性峰都向低温偏移,并使负载后的赤泥具有了较高的Fe离子平均氧化态以及较高的Cu+含量,促进了赤泥催化剂对低温NO的转化率。

Electrochemical corrosion of Sn-0.75Cu solder joints in NaCl solution

The corrosion behaviors of Sn-0.75Cu solder and Sn-0.75Cu/Cu joint in 3.5% NaCl（mass fraction） solution were studied by potentiodynamic polarization test and leaching measurement.The polarization curves indicated that the corrosion rate of Sn-0.75Cu solder was lower than that of Sn-0.75Cu/Cu joint.The morphology observation and phase composition analysis on the corroded product at each interesting potential suggested that Sn3O（OH）2Cl2 formed on the surface of Sn-0.75Cu solder at active dissolution stage.As the potential increased from active/passive transition stage,all the surface of Sn-0.75Cu solder was covered by the Sn3O（OH）2Cl2 and some pits appeared after the polarization test.Compared to the Sn-0.75Cu solder alloy,much more Sn3O（OH）2Cl2 formed at active dissolution stage and the pits with bigger size were observed after polarization test for the Sn-0.75Cu/Cu solder joints.The leaching test confirmed that the faster electrochemical corrosion rate resulted in the larger amount of Sn released from the Sn-0.75Cu/Cu solder joints.

Cu、Sn、Ag同位素在古金属制品溯源研究中的应用

近年来,随着同位素分析方法的不断突破和新一代多接收电感耦合等离子体质谱(MC-ICP-MS)测试技术的广泛应用,Cu、Sn、Ag等非传统同位素在古代金属制品溯源研究中显示出较好的应用前景。本文综述了近20年来Cu、Sn、Ag同位素在古代金属制品应用研究的相关进展,并展望了其应用前景:①由于不同矿床之间Cu、Sn、Ag同位素存较大重叠,这些同位素均难以作为独立的证据追溯金属制品的地质来源;②Cu同位素在原生矿石与表生矿石之间存在较大的分馏,是示踪铜矿石类型的可靠方法,Ag同位素也具推断银矿石类型的潜力;③将Cu、Sn、Ag同位素与Pb同位素、微量元素相结合,并采用合理的统计方法,开展综合溯源研究将是今后应用非传统同位素进行古代金属制品溯源研究的发展方向。

贝氏体钢时效处理富Cu团簇析出特点及其第一性原理计算

研究低碳贝氏体钢(15Cr12CuSiMoMn)时效处理过程中富Cu团簇的析出演变特点,并基于第一性原理计算,采用特殊准随机结构(Special quasirandom structures,SQS)、Solid-State Nudged Elastic Band(SSNEB)方法构建Fe-Cu二元体系的无序固溶体结构模型,模拟计算相变能量路径,分析并表征析出相析出演变规律与模拟计算之间的相互联系。结果表明,实验钢在指定温度(500℃)进行时效热处理,时效处理各阶段实验钢中弥散析出约2.6~53 nm的富Cu团簇,以共格、非共格状态存在于基体中,经模拟计算,BCC-Cu向9R-Cu转变过程中需在开始阶段克服8.9 meV的能垒,之后从9R-Cu向孪晶FCC-Cu+9R-Cu结构转变过程中需要克服4.9 meV的能垒,非稳态BCC富Cu团簇与稳定态的FCC Cu之间具有0.14 eV/atom的形成能差,当Cu含量超过21.6%(原子分数)后,富Cu团簇从BCC结构不断向稳定的纯FCC-Cu结构演变。从能量角度分析了富Cu团簇析出倾向,解释了富Cu团簇的析出惯序,有利于优化贝氏体组织,为含Cu贝氏体沉淀钢的深入研究及相关领域的开发拓展提供理论参考依据。