Chemistry-mechanics-geometry coupling in positive electrode materials: a scale-bridging perspective for mitigating degradation in lithium-ion batteries through materials design.

Despite their rapid emergence as the dominant paradigm for electrochemical energy storage, the full promise of lithium-ion batteries is yet to be fully realized, partly because of challenges in adequately resolving common degradation mechanisms. Positive electrodes of Li-ion batteries store ions in interstitial sites based on redox reactions throughout their interior volume. However, variations in the local concentration of inserted Li-ions and inhomogeneous intercalation-induced structural transformations beget substantial stress. Such stress can accumulate and ultimately engender substantial delamination and transgranular/intergranular fracture in typically brittle oxide materials upon continuous electrochemical cycling. This perspective highlights the coupling between electrochemistry, mechanics, and geometry spanning key electrochemical processes: surface reaction, solid-state diffusion, and phase nucleation/transformation in intercalating positive electrodes. In particular, we highlight recent findings on tunable material design parameters that can be used to modulate the kinetics and thermodynamics of intercalation phenomena, spanning the range from atomistic and crystallographic materials design principles (based on alloying, polymorphism, and pre-intercalation) to emergent mesoscale structuring of electrode architectures (through control of crystallite dimensions and geometry, curvature, and external strain). This framework enables intercalation chemistry design principles to be mapped to degradation phenomena based on consideration of mechanics coupling across decades of length scales. Scale-bridging characterization and modeling, along with materials design, holds promise for deciphering mechanistic understanding, modulating multiphysics couplings, and devising actionable strategies to substantially modify intercalation phase diagrams in a manner that unlocks greater useable capacity and enables alleviation of chemo-mechanical degradation mechanisms.

Chemotherapy and Abdominal Wall Closure Technique Increase the Probability of Postoperative Ventral Incisional Hernia in Patients With Colon Cancer.

BACKGROUND: Chemotherapy is associated with postoperative ventral incisional hernia (PVIH) after right hemicolectomy (RHC) for colon cancer, and abdominal wall closure technique may affect PVIH. We sought to identify clinical predictors of PVIH. METHODS: We retrospectively analyzed patients who underwent RHC for colon cancer from 2008-2018 and later developed PVIH. Time to PVIH was analyzed with Kaplan-Meier analysis, clinical predictors were identified with multivariable Cox proportional hazards modeling, and the probability of PVIH given chemotherapy and the suture technique was estimated with Bayesian analysis. RESULTS: We identified 399 patients (209 no adjuvant chemotherapy and 190 adjuvant chemotherapy), with an overall PVIH rate of 38%. The 5-year PVIH rate was 55% for adjuvant chemotherapy, compared with 38% for none (log-rank P < .05). Adjuvant chemotherapy (hazard ratio [HR] 1.65, 95% confidence interval [CI] 1.18-2.31, P < .01), age (HR .99, 95% CI .97-1.00, P < .01), body mass index (HR 1.02, 95% CI 1.00-1.04, P < .01), and neoadjuvant chemotherapy (HR 1.92, 95% CI 1.21-3.00, P < .01) were independently associated with PVIH. Postoperative ventral incisional hernia was more common overall in patients who received adjuvant chemotherapy (46% compared with 30%, P < .01). In patients who received adjuvant chemotherapy, the probability of PVIH for incision closure with #1 running looped polydioxanone was 42%, compared with 59% for incision closure with #0 single interrupted polyglactin 910. DISCUSSION: Exposure to chemotherapy increases the probability of PVIH after RHC, and non-short stitch incision closure further increases this probability, more so than age or body mass index. The suture technique deserves further study as a modifiable factor in this high-risk population.

Multivariate hyperspectral data analytics across length scales to probe compositional, phase, and strain heterogeneities in electrode materials.

The origins of performance degradation in batteries can be traced to atomistic phenomena, accumulated at mesoscale dimensions, and compounded up to the level of electrode architectures. Hyperspectral X-ray spectromicroscopy techniques allow for the mapping of compositional variations, and phase separation across length scales with high spatial and energy resolution. We demonstrate the design of workflows combining singular value decomposition, principal-component analysis, k-means clustering, and linear combination fitting, in conjunction with a curated spectral database, to develop high-accuracy quantitative compositional maps of the effective depth of discharge across individual positive electrode particles and ensembles of particles. Using curated reference spectra, accurate and quantitative mapping of inter- and intraparticle compositional heterogeneities, phase separation, and stress gradients is achieved for a canonical phase-transforming positive electrode material, α-V2O5. Phase maps from single-particle measurements are used to reconstruct directional stress profiles showcasing the distinctive insights accessible from a standards-informed application of high-dimensional chemical imaging.

Data science enables X-ray vision.

In their recent publication in Patterns, the authors proposed a novel workflow to derive compositional and stress maps for positive electrode materials of Li-ion batteries from hyperspectral X-ray imaging data. They describe their interdisciplinary collaboration, the elements that sustain such collaborations, and their effect on the flourishing of the domain and data science.

Protocolized Training of Advanced Practice Providers for Robotic Surgery Improves the Quality of Intraoperative Assistance.

BACKGROUND: The expansion of robotic surgery requires identifying factors of competent robotic bedside assisting. Surgical trainees desire more robotic console time, and we hypothesized that protocolized robotic surgery bedside training could equip Advanced Practice Providers (APPs) to meet this growing need. No standardized precedent exists for training APPs. METHODS: We designed a pilot study consisting of didactic and clinical skills. APPs completed didactic tests followed by proctored clinical skills checklists intraoperatively. Operating surgeons scored trainees with 10-point Likert scale (< 5 not confident, > 5 = confident). APPs scoring > 5 advanced to a solo practicum. Competence was defined as: didactic test score > 75th percentile, completing < 5 checklists, scoring > 5 on the practicum. The probability of passing the practicum was calculated with Bayes theorem. RESULTS: Of 10 APP trainees, 5 passed on initial attempt. After individualized development plans, 4 passed retesting. Differences in trainee factors were not statistically significant, but the probability of passing the practicum was < 50% if more than four checklists were needed. CONCLUSIONS: Clinical experience, not didactic knowledge, determines the probability of intraoperative competence. Increasing clinical proctoring did not result in higher probability of competence. Early identification of APPs needing individualized improvement increases the proportion of competent APPs.

Cation reordering instead of phase transitions: Origins and implications of contrasting lithiation mechanisms in 1D ζ- and 2D α-V2O5.

Substantial improvements in cycle life, rate performance, accessible voltage, and reversible capacity are required to realize the promise of Li-ion batteries in full measure. Here, we have examined insertion electrodes of the same composition (V2O5) prepared according to the same electrode specifications and comprising particles with similar dimensions and geometries that differ only in terms of their atomic connectivity and crystal structure, specifically two-dimensional (2D) layered α-V2O5 that crystallizes in an orthorhombic space group and one-dimensional (1D) tunnel-structured ζ-V2O5 crystallized in a monoclinic space group. By using particles of similar dimensions, we have disentangled the role of specific structural motifs and atomistic diffusion pathways in affecting electrochemical performance by mapping the dynamical evolution of lithiation-induced structural modifications using ex situ scanning transmission X-ray microscopy, operando synchrotron X-ray diffraction measurements, and phase-field modeling. We find the operation of sharply divergent mechanisms to accommodate increasing concentrations of Li-ions: a series of distortive phase transformations that result in puckering and expansion of interlayer spacing in layered α-V2O5, as compared with cation reordering along interstitial sites in tunnel-structured ζ-V2O5 By alleviating distortive phase transformations, the ζ-V2O5 cathode shows reduced voltage hysteresis, increased Li-ion diffusivity, alleviation of stress gradients, and improved capacity retention. The findings demonstrate that alternative lithiation mechanisms can be accessed in metastable compounds by dint of their reconfigured atomic connectivity and can unlock substantially improved electrochemical performance not accessible in the thermodynamically stable phase.

Custom 3D-printed Titanium Implant for Reconstruction of a Composite Chest and Abdominal Wall Defect.

BACKGROUND: Three-dimensional (3D) printing of implantable materials is a recent technological advance that is available for clinical application. The most common medical application of 3D printing in plastic surgery is in the field of craniomaxillofacial surgery. There have been few applications of this technology in other areas. METHODS: Here, we discuss a case of a large, symptomatic composite thoracic and abdominal defect resulting from the resection of a chondrosarcoma of the costal marginand sections of the abdominal wall, diaphragm, and sternum. The initial and second attempts at reconstruction failed, resulting in a massive hernia. Given the size of the defect, the contiguity with a large abdominal wall defect, and the high risk of recurrence, a rigid thoracic reconstruction was essential to durably repair the thoracic hernia and serve as a scaffold to which both the diaphragm and the abdominal mesh could be secured. A custom-made plate offered the most durable and anatomically accurate reconstruction in this particular clinical scenario. This technology was used in concert with a single section of coated mesh for reconstruction of the diaphragm, chest wall, and abdominal wall. RESULTS: There were no post-operative complications. The patient has improvement of his symptoms and increased functional capacity. There is no evidence of hernia recurrence 1.5 years after repair. CONCLUSIONS: 3D printing technology proved to be a useful and effective application for reconstruction of this large thoracic defect involving the costal margin. It is an available technology that should be considered for reconstruction of rigid structures with defect-specific precision.

Assessing the role of vanadium technologies in decarbonizing hard-to-abate sectors and enabling the energy transition.

The decarbonization of heavy industry and the emergence of renewable energy technologies are inextricably linked to access to mineral resources. As such, there is an urgent need to develop benchmarked assessments of the role of critical elements in reducing greenhouse gas emissions. Here, we explore the role of vanadium in decarbonizing construction by serving as a microalloying element and enabling the energy transition as the primary component of flow batteries used for grid-level storage. We estimate that vanadium has enabled an avoided environmental burden totaling 185 million metric tons of CO2 on an annual basis. A granular analysis estimates savings for China and the European Union at 1.15% and 0.18% of their respective emissions, respectively. Our results highlight the role of critical metals in developing low-carbon infrastructure while underscoring the need for holistic assessments to inform policy interventions that mitigate supply chain risks.

Punching above its weight: life cycle energy accounting and environmental assessment of vanadium microalloying in reinforcement bar steel.

Steel-reinforced concrete is ubiquitously used in construction across the world. The United Nations estimates that the worldwide energy consumption of buildings accounts for 30-40% of global energy production, underlining the importance of the judicious selection of construction materials. Much effort has focused on the use of high-strength low-alloy steels in reinforcement bars whose economy of materials use is predicated upon improved yield strengths in comparison to low-carbon steels. While microalloying is known to allow for reduced steel consumption, a sustainability analysis in terms of embodied energy and CO2 has not thus far been performed. Here we calculate the impact of supplanting lower grade reinforcement bars with higher strength vanadium microalloyed steels on embodied energy and carbon footprint. We find that the increased strength of vanadium microalloyed steel translates into substantial material savings over mild steel, thereby reducing the total global fossil carbon footprint by as much as 0.385%. A more granular analysis pegs savings for China and the European Union at 1.01 and 0.19%, respectively, of their respective emissions. Our cradle-to-gate analysis provides an accounting of the role of microalloying in reducing the carbon footprint of the steel and construction industries and highlights the underappreciated role of alloying elements.

The current state of robotic retromuscular repairs-a qualitative review of the literature.

BACKGROUND: The management of ventral incisional hernias (VIH) has undergone many iterations over the last 5 years due to evolution in surgical techniques and advancement in robotic surgery. Four general principles have emerged: mesh usage, retromuscular mesh placement, primary fascial closure, and usage of minimally invasive techniques when possible. The application of robotic retromuscular repairs in VIH allow these principles to be applied simultaneously. This qualitative review attempts to answer what robotic retromuscular repairs are described, which patients are selected for these techniques, and what are current outcomes. METHODS: Using the key words: "robotic retromuscular repair", "robotic Rives Stoppa", and "robotic transversus abdominis release", a PubMed search of articles written up to December 2019 was critically reviewed. RESULTS: 44 articles were encountered, 9 high-quality articles were analyzed for this manuscript. Level of evidence ranged from 2B to 2C. Robotic TAR patients had BMI of 33 kg/m2, defect sizes ranging from 7-14 cm wide to 12-19 cm long, longer OR times, no difference in surgical site events, and shorter length of stay (LOS). The techniques to perform robotic Rives Stoppa (RS) were heterogeneous; however, extended totally extraperitoneal (ETEP) approach is most described. Defect width for RS repairs ranged 4-7 cm and LOS was less than 1 day. Complication rates were low, there is no long-term data on hernia recurrence, and information on cost is limited. CONCLUSION: In short-term follow-up, robotic retromuscular repairs show promise that VIH can be repaired with intramuscular mesh, few complications, and shorter LOS. Data on hernia recurrence, long-term complications, and rigorous cost analysis are needed to demonstrate generalizability.

Predictors of Failed Transcystic Laparoscopic Common Bile Duct Exploration: Analysis of Multicenter Integrated Health System Database.

BACKGROUND: The aim of this study is to report our experience with laparoscopic common bile duct exploration (LCBDE) and validate the experts' opinion about anatomical predictors of failed transcystic LCBDE (TLCBDE) approach. METHODS: Patients undergoing LCBDE at Kaiser Permanente Southern California hospitals (2005-2015) were included. Predictors of failed TLCBDE were identified using bivariate analysis. RESULTS: Of 115 LCBDE, 89.6% were TLCBDE and 10.4% through choledochotomy. Success rate, morbidity, and length of hospital stay were 83.5%, 6.1%, and 3.8 days respectively. Only stone size:cystic duct ratio >1 (35% versus 63%, P = .044) was associated with failure of TLCBDE. In accordance with experts' opinion, there was a suggestive association of stone size ≥6 mm, cystic duct ≤4 mm, multiple stones, and proximal stone location with failure; however, these did not reach statistical significance. CONCLUSION: LCBDE is an effective and safe mean of clearing common bile duct stones at community hospitals of an integrated health system. Previously cited contraindications for TLCBDE are not absolute, but rather predictors of failure.

Laparoscopic common bile duct exploration versus endoscopic retrograde cholangiopancreatography for choledocholithiasis found at time of laparoscopic cholecystectomy: Analysis of a large integrated health care system database.

BACKGROUND: We compared endoscopic retrograde cholangiopancreatography (ERCP) and laparoscopic common bile duct exploration (LCBDE) for managing choledocholithiasis found at time of cholecystectomy. METHODS: One hundred and five LCBDE (2005-2015) were compared to 195 LC/ERCP (2014-2015) from the Southern California Kaiser Permanente database. RESULTS: LC/ERCP was more effective at clearing the CBD (98% vs. 88.6%, p = 0.01); but required more procedures per patient (mean ± standard deviation, 1.1 ± 0.4 vs. 2.0 ± 0.12, p < 0.001). Morbidity, hospital length of stay and readmission were not different (P > 0.05). Four patients failed ERCP, while 12 patients failed LCBDE and had subsequent ERCP (10) or CBD exploration (2). All patients with RYGB had successful LCBDE. CONCLUSION: LC/ERCP is better than LCBDE in clearing CBD stones, but has similar morbidity and is an effective alternative for patients with RYGB.

How often does computed tomography change the management of acute appendicitis?

Computed tomography (CT) diagnoses appendicitis accurately, but few studies evaluate how often CT changes the management of appendicitis. Consultations for appendicitis were evaluated by surgeons and assigned to groups: high, indeterminate, and low suspicion. After assignment, CT was reviewed if completed or ordered if desired by the surgeon and changes in plans were noted. One hundred patients were evaluated for appendicitis, 70 received appendectomy. Our negative appendectomy rate was 4 of 70 (5.7%). In the high suspicion group, 63 patients had 23 CT scans performed and 2 CT scans were negative, avoiding unnecessary operation and changing management in 2 of 63 (3.2%). The intermediate suspicion group included 27 patients and 26 CT scans performed; 11 were positive resulting in nine positive appendectomies and changing management in 9 of 27 (33%). The low suspicion group had 7 CT scans performed; two were positive leading to two positive appendectomies and changing management in 2 of 10 (20%). CT promoted 10 of 100 patients to the interval appendectomy pathway with no failures in delayed operative management. CT rarely changes management in patients highly suspicious for appendicitis, but may have a role in selecting patients for interval appendectomy. CT frequently changes management if the clinical diagnosis is indeterminate.