Status of the BELLE II Pixel Detector

The Belle II experiment at the super KEK B-factory (SuperKEKB) in Tsukuba, Japan, has been collecting $e^+e^−$ collision data since March 2019. Operating at a record-breaking luminosity of up to $4.7×10^{34} cm^{−2}s^{−1}$, data corresponding to $424 fb^{−1}$ has since been recorded. The Belle II VerteX Detector (VXD) is central to the Belle II detector and its physics program and plays a crucial role in reconstructing precise primary and decay vertices. It consists of the outer 4-layer Silicon Vertex Detector (SVD) using double sided silicon strips and the inner two-layer PiXel Detector (PXD) based on the Depleted P-channel Field Effect Transistor (DePFET) technology. The PXD DePFET structure combines signal generation and amplification within pixels with a minimum pitch of $(50×55) μm^2$. A high gain and a high signal-to-noise ratio allow thinning the pixels to $75 μm$ while retaining a high pixel hit efficiency of about $99$. As a consequence, also the material budget of the full detector is kept low at $≈0.21$$\frac{X}{X_0}$ per layer in the acceptance region. This also includes contributions from the control, Analog-to-Digital Converter (ADC), and data processing Application Specific Integrated Circuits (ASICs) as well as from cooling and support structures. This article will present the experience gained from four years of operating PXD; the first full scale detector employing the DePFET technology in High Energy Physics. Overall, the PXD has met the expectations. Operating in the intense SuperKEKB environment poses many challenges that will also be discussed. The current PXD system remains incomplete with only 20 out of 40 modules having been installed. A full replacement has been constructed and is currently in its final testing stage before it will be installed into Belle II during the ongoing long shutdown that will last throughout 2023

Genetics of the thrombomodulin-endothelial cell protein C receptor system and the risk of early-onset ischemic stroke

Background and purpose Polymorphisms in coagulation genes have been associated with early-onset ischemic stroke. Here we pursue an a priori hypothesis that genetic variation in the endothelial-based receptors of the thrombomodulin-protein C system (THBD and PROCR) may similarly be associated with early-onset ischemic stroke. We explored this hypothesis utilizing a multi-tage design of discovery and replication. Methods Discovery was performed in the Genetics-of-Early-Onset Stroke (GEOS) Study, a biracial population-based case-control study of ischemic stroke among men and women aged 1549 including 829 cases of first ischemic stroke (42.2% African-American) and 850 age-comparable stroke-free controls (38.1% African-American). Twenty-four single-nucleotide-polymorphisms (SNPs) in THBD and 22 SNPs in PROCR were evaluated. Following LD pruning (r(2)>= 0.8), we advanced uncorrelated SNPs forward for association analyses. Associated SNPs were evaluated for replication in an early-onset ischemic stroke population (onset-ge Results Among GEOS Caucasians, PROCR rs9574, which was in strong LD with 8 other SNPs, and one additional independent SNP rs2069951, were significantly associated with ischemic stroke (rs9574, OR = 1.33, p = 0.003; rs2069951, OR = 1.80, p = 0.006) using an additive-model adjusting for age, gender and population-structure. Adjusting for risk factors did not change the associations; however, associations were strengthened among those without risk factors. PROCR rs9574 also associated with early-onset ischemic stroke in the replication sample (OR = 1.08, p = 0.015), but not older-onset stroke. There were no PROCR associations in African-Americans, nor were there any THBD associations in either ethnicity. Conclusion PROCR polymorphisms are associated with early-onset ischemic stroke in Caucasians.Peer reviewe

Impact of Silicon Content and Particle Size in Lithium-Ion Battery Anodes on Particulate Properties and Electrochemical Performance

Silicon (Si) is considered a promising anode active material to enhance energy density of lithium-ion batteries. Many studies have focused on new structures and the electrochemical performance, but only a few investigated the particulate properties in detail. Therefore, a comprehensive study on the impact of Si content (5, 10, 15 wt.%) and particle size (120, 160, 250 nm) of core–shell structured Si@Gr composites on particulate and electrode properties was conducted. It was shown that both parameters had significant impact on the specific surface area (SSA) of particles, which was later correlated to the initial capacities and coulombic efficiencies (ICEs). Furthermore, changes in pore size distribution and electrical conductivity were found. The built full cells showed high initial capacities (>150 mAh g−1), good rate capability (75% at 1 C, 50% at 2 C) and ICEs (>80%). The energy density was found to increase by 32% at 15 wt.% Si compared to graphite (Gr), indicating the future potential of Si. In addition, the impact of a carbon coating was investigated (Si@Gr/C), which led to a reduction in SSA, improved particle stability and higher capacity retention. Consequently, this study emphasizes the importance of also investigating the particulate properties of Si anodes

Spherical Graphite Anodes: Influence of Particle Size Distribution and Multilayer Structuring in Lithium-Ion Battery Cells

Current research focuses on lithium-ion battery cells with a high energy density and efficient fast-charging capabilities. However, transport limitations, and, therefore, the uniform diffusion of lithium-ions across the electrode layers, remain a challenge and could lead to reduced cell performance. One approach to overcome these transport challenges is the use of subsequently produced two-layer anodes with the particle size variation of spherical graphite (x50 = 18 µm; x50 = 11 µm). Thereby, a defined pore network is created, which reduces the ionic resistance and ensuring improved fast charging capabilities. The analysis focuses on the evaluation of electrode properties and the electrochemical performance. By examining the pore size distribution of the anodes, it has been found that during the manufacturing of the two-layer anodes, carbon black and binder particles are transported into the existing microstructure of the lower layer, resulting in localized densification between the anode layers. This could also be supported by color measurements. This effect also extends to electrochemical investigations, with electrochemical impedance spectroscopy showing significantly lower ionic resistances in all two-layer anodes. Reduced ionic resistance and tortuosity near the separator due to absorption effects enhance the ion diffusion and have a direct impact on anode performance. Cell ageing analysis showed a significant capacity decrease of almost 15 mAh g −1 in the single-layer references only, in contrast to the stability of the two-layer anodes. This could also be attributed to the reduced ionic resistance and active counteraction of binder migration. In conclusion, this study highlights how subsequently produced two-layer anodes significantly shape the electrode properties and cell performance of lithium-ion batteries

Impact of Spheroidization of Natural Graphite on Fast-Charging Capability of Anodes for LIB

Despite numerous research on new active materials for anodes, graphite remains the most commonly used material in Li-ion batteries. The spherical shape of the graphite particles has proven to be beneficial for application in electric vehicles, especially for fast charging. So far, the spheroidization of natural flake graphite is conducted by a rigid and inefficient cascade process. In this work, a scalable classifier system was used for spheroidization, and it was demonstrated that a spheroidization time of 15 min is sufficient to improve material properties and enhance electrochemical performance while maintaining high process yields of 55%. Insights into the influence of the morphology on the intrinsic and structural properties of the graphite particles and manufactured electrodes are provided. Spheroidization creates a more efficient pore network in the coating layer while reducing the internal resistance and increasing the surface area of the particles by a factor of 1.8. We demonstrate that the spherical shape improves the discharge rate capability by 1.8, and the specific charge capacity could be enhanced by more than 237% at a C-rate of 3. An additional carbon coating could significantly decrease the specific surface area and increase the specific capacity at high C-rates

K-Wire Osteosynthesis for Arthrodesis of the Paediatric Foot Is a Good and Valid Procedure

Background: Foot deformities in children are common, and the majority can be treated conservatively. Nevertheless, there are deformities that require surgical treatment. These include rigid clubfeet, severe forms of pes planovalgus, pes cavus and several more. We retrospectively analysed the pseudarthrosis rate of surgical treatment of foot deformities with transcutaneous K-wire osteosynthesis in neurologically healthy children and adolescents. The aim of the study was to show that the results with K-wires are comparable to those with other osteosynthesis methods in the literature. Methods: A total of 46 paediatric patients aged 6 to 17 years treated between January 2010 and December 2015 met the inclusion criteria. Depending on the diagnosis, different surgical interventions were necessary. In clubfoot and pes planovalgus, representing n = 81, 70% of the whole collective triple arthrodesis with fusion of the talonavicular, calcaneocuboid and subtalar joints or Evans osteotomy was usually performed. Radiographs were taken at least 6 months post-surgery, and bony consolidation of the subtalar, talonavicular (TN), and calcaneocuboidal (CC) joints and the metatarsal I (MT I) osteotomy were assessed. If there was no evidence of fusion at this time, it was considered non-union. Results: In total, 117 arthrodesis procedures with K-wires were performed. Overall, 110 of the arthrodesis (94%) healed, and only 7 joints (6%) showed non-union (subtalar 0%, TN 7.7%, CC 6.5% and MT I 6.7%). All non-unions occurred in subjects with clubfoot deformities. No significant risk factors were observed. Conclusion: This study replicated the good consolidation rates reported in the literature with screws, plates, intramedullary nails or staples in arthrodesis of the adolescent foot in neurologically healthy subjects and confirmed the efficacy of K-wires. The main advantages of transcutaneous K-wire treatment are easy metal removal, lower osteosynthesis material costs and less concomitant damage. Further studies, especially randomised controlled trials, are needed to further investigate this topic

Multicomponent Comminution within a Stirred Media Mill and Its Application for Processing a Lithium-Ion Battery Slurry

This study presents an approach for targeted comminution of component mixtures within a wet-operated stirred media mill. In the first step, a general understanding of the interactions between individual components on the grinding result with mixtures could be gained with basic experiments and following our former research work. In particular, a protective effect of the coarser particles on the fines could be elucidated. These findings were used to develop a process for the production of a battery slurry containing fine ground silicon particles as well as dispersed carbon black and graphite particles. By a tailored sample preparation applying a combination of particle dissolution and separation, the particle size distributions of carbon black and graphite particles were analyzed separately within the produced battery slurries. Based on the selective particle size analysis, the slurry preparation could be transferred from a complex multistage batch process using a dissolver to a stirred media mill, which was finally operated in a continuous one-passage mode. The prepared slurries were subsequently further processed to silicon-rich anodes using a pilot scale coating and drying plant. Afterward, the produced anodes were electrochemically characterized in full cells. The cell results prove a comparable electrochemical behavior of anode coatings derived from a dissolver- or mill-based slurry production process. Therefore, we could demonstrate that it is possible to integrate the mixing process for the production of multicomponent slurries into the comminution process for the preparation of individual materials upstream. Even with nearly identical starting sizes of their feed materials, the targeted particle size distributions of the single components can be reached, taking into account the different material-dependent particle strengths and sequential addition of single components to the multicomponent comminution process

Investigating the Influence of the Effective Ionic Transport on the Electrochemical Performance of Si/C-Argyrodite Solid‐State Composites

Solid-state batteries have the potential to outperform conventional lithium-ion batteries, as they offer higher energy densities, necessary for the increasing demand for portable energy storage. Silicon-graphite composites are considered to be one of the most promising alternatives to the lithium metal anode due to their low lithiation potential and resistance against dendrite formation. Since these composites show insufficient ionic conductivity, a fast-conducting solid electrolyte is needed to facilitate the charge carrier transport. Optimizing the volume fractions of the solid electrolyte is crucial to ensure sufficient charge carrier transport and achieve the optimal performance. In this work, the influence of the charge carrier transport in a silicon on graphite (Si/C)/argyrodite solid electrolyte composite on the electrochemical performance is studied. By systematically varying the ratio of the Si/C to solid electrolyte, it was found that the effective ionic conductivity of the electrode composite improves exponentially with increasing content of the solid electrolyte, which in turn leads to an increase in the specific capacity of the composite across all C-rates. This study highlights the importance of understanding and customizing charge carrier transport properties in solid-state anode composites to achieve optimum electrochemical performance

Crystal structure and high-pressure phase behavior of a CaCO3_3–SrCO3_3 solid solution

A synthetic CaCO$_3$–SrCO$_3$ solid solution with composition Ca$_{0.82}$ Sr$_{0.18}$CO$_3$ was investigated by single-crystal X-ray diffraction in the pressure range between 0 and 22 GPa using different pressure-transmitting media. The samples were compressed in DACs using Ne up to ∼9 GPa and Ar up to ∼22 GPa. At ambient conditions, Ca$_{0.82}$ Sr$_{0.18}$CO$_3$ crystallizes in a monoclinic structure, isostructural to CaCO$_3$-II, Sr-calcite-II (Sr-CC-II), with space group P2$_1$∕c , 4 formula units per unit cell, Z, a = 6.4237(7) Å, b = 5.0176(1) Å, c = 8.1129(1) Å, = 108.064(1)◦ and V = 248.60(1) Å$^3$ (where the number in parenthesis is 1 uncertainties on the last digit). At 1.72(5) GPa, a structural phase transition is observed to a new monoclinic structure, Sr-calcite-IIIc (Sr-CC-IIIc), with space group P2$_1$∕m and Z = 8 ( a = 6.2683(2) Å, b = 9.9220(5) Å, c = 7.6574(6) Å, = 103.856(6)◦ and V = 462.39(5) Å$^3$ ), different from any pure CaCO$_3$ polymorph. At 12 GPa, the sample transformed to a triclinic structure, Sr-calcite-IIIb (Sr-CC-IIIb), with space group P̄1 and Z = 4 ( a = 6.059(5) Å, b = 6.280(2) Å, c = 6.331(2) Å, = 95.20(3)◦, = 108.89(5)◦, = 110.52(5)◦ and V = 207.7(2) Å$^3$ ), isostructural to end-member CaCO$_3$-IIIb. Finally, at 17 GPa, a transition is observed to Sr-calcite-VI (Sr-CC-VI), with space group P̄1 and Z = 2 (a = 3.444(3) Å, b = 4.985(4) Å, c = 5.761(5) Å, = 77.05(7)◦, = 84.92(7)◦, = 89.00(7)◦ and V = 96.0(1) Å$^3$), isostructural to end-member CaCO$_3$-VI, which is preserved up to the maximum investigated pressure of 22 GPa. The results of this study show the effect of Sr/Ca cationic substitution on the high-pressure behavior and physical properties of a CaCO$_3$–SrCO$_3$ solid solution. The phase evolution of Ca$_{0.82}$ Sr$_{0.18}$CO$_3$ and the crystallization of a new phase, Sr-CC-IIIc, different from the high-pressure polymorphs of end-member CaCO$_3$, point to the importance of extending the study of carbonates to more complex systems than pure end-member compositions

Comminution and Classification as Important Processes for the Circular Production of Lithium Batteries

   This presentation explores the pivotal role of comminution and classification processes in fostering the circular production of lithium batteries. Beginning with an overview of the sustainability challenges within lithium-ion battery (LiB) production, it delves into the sustainable production of electrodes and cells. Key topics include the integration of comminution and classification processes into electrode material synthesis, mechanochemical synthesis for solid electrolytes, and the importance of dispersion in enhancing battery performance. Additionally, it highlights advancements in recycling processes for production scrap and end-of-life batteries. The presentation concludes with a forward-looking perspective on the future of milling and classification processes in shaping the energy storage materials industry.</p