Microstructural Insights into Performance Loss of High-Voltage Spinel Cathodes for Lithium-ion Batteries.

Spinel-structured LiNix Mn2-x O4 (LNMO), with low-cost earth-abundant constituents, is a promising high-voltage cathode material for lithium-ion batteries. Even though extensive electrochemical investigations have been conducted on these materials, few studies have explored correlations between their loss in performance and associated changes in microstructure. Here, down to the atomic scale, the structural evolution of these materials is investigated upon the progressive cycling of lithium-ion cells. Transgranular cracking is revealed to be a key feature during cycling; this cracking is initiated at the particle surface and leads to the penetration of electrolytes along the crack path, thereby increasing particle exposure to the electrolyte. The lattice structure on the crack surface shows spatial variances, featuring a top layer of rock-salt, a sublayer of a Mn3 O4 -like arrangement, and then a mixed-cation region adjacent to the bulk lattice. The transgranular cracking, along with the emergence of local lattice distortion, becomes more evident with extended cycling. Further, phase transformation at primary particle surfaces and void formation through vacancy condensation is found in the cycled samples. All these features collectively contribute to the performance degradation of the battery cells during electrochemical cycling.

Hypermethylation at CREBBP Is Associated with Cognitive Impairment in a Mexican American Cohort.

BACKGROUND: The aging Mexican American (MA) population is the fastest growing ethnic minority group in the US. MAs have a unique metabolic-related risk for Alzheimer's disease (AD) and mild cognitive impairment (MCI), compared to non-Hispanic whites (NHW). This risk for cognitive impairment (CI) is multifactorial involving genetics, environmental, and lifestyle factors. Changes in environment and lifestyle can alter patterns and even possibly reverse derangement of DNA methylation (a form of epigenetic regulation). OBJECTIVE: We sought to identify ethnicity-specific DNA methylation profiles that may be associated with CI in MAs and NHWs. METHODS: DNA obtained from peripheral blood of 551 participants from the Texas Alzheimer's Research and Care Consortium was typed on the Illumina Infinium® MethylationEPIC chip array, which assesses over 850K CpG genomic sites. Within each ethnic group (N = 299 MAs, N = 252 NHWs), participants were stratified by cognitive status (control versus CI). Beta values, representing relative degree of methylation, were normalized using the Beta MIxture Quantile dilation method and assessed for differential methylation using the Chip Analysis Methylation Pipeline (ChAMP), limma and cate packages in R. RESULTS: Two differentially methylated sites were significant: cg13135255 (MAs) and cg27002303 (NHWs) based on an FDR p < 0.05. Three suggestive sites obtained were cg01887506 (MAs) and cg10607142 and cg13529380 (NHWs). Most methylation sites were hypermethylated in CI compared to controls, except cg13529380 which was hypomethylated. CONCLUSION: The strongest association with CI was at cg13135255 (FDR-adjusted p = 0.029 in MAs), within the CREBBP gene. Moving forward, identifying additional ethnicity-specific methylation sites may be useful to discern CI risk in MAs.

Fluctuation cepstral scanning transmission electron microscopy of mixed-phase amorphous materials.

Four-dimensional scanning transmission electron microscopy (4D-STEM) is a versatile analytical tool for characterizing materials structural properties. However, extending such analysis to disordered materials is challenging, especially in technologically important samples with mixed ordered and disordered phases. Here, we present a new 4D-STEM method, called fluctuation cepstral STEM (FC-STEM), based on the fluctuation analysis of cepstral transform of diffraction patterns. The peaks in the associated transformation relate to inter-atomic distances in a thin sample. By varying the real-space range over which fluctuations are calculated, distinct ordered and disordered phases can be mapped in a diffractive image reconstruction. We demonstrate the principles of FC-STEM by characterizing a silicon anode, harvested from a cycled lithium-ion battery. A mixture of amorphous and nanocrystalline silicon, graphitic carbon, and electrolyte by-products is identified and mapped. Comparisons with conventional electron imaging and energy-dispersive X-ray spectroscopy show that FC-STEM is highly effective for the structure determination of mixed-phase amorphous materials.

Sequence adaptive field-imperfection estimation (SAFE): retrospective estimation and correction of $B_1

$B_1^+$ and $B_0$ field-inhomogeneities can significantly reduce accuracy and robustness of MRF's quantitative parameter estimates. Additional $B_1^+$ and $B_0$ calibration scans can mitigate this but add scan time and cannot be applied retrospectively to previously collected data. Here, we proposed a calibration-free sequence-adaptive deep-learning framework, to estimate and correct for $B_1^+$ and $B_0$ effects of any MRF sequence. We demonstrate its capability on arbitrary MRF sequences at 3T, where no training data were previously obtained. Such approach can be applied to any previously-acquired and future MRF-scans. The flexibility in directly applying this framework to other quantitative sequences is also highlighted.

Physicochemical Heterogeneity in Silicon Anodes from Cycled Lithium-Ion Cells.

The severe capacity fade of lithium-ion cells with silicon-dominant anodes has hindered their widescale commercialization. In this work, we link cell capacity fade to the heterogeneous physicochemical evolution of silicon anodes during battery cycling. Through a multilength scale characterization approach, we demonstrate that silicon particles near the anode surface react differently from those near the copper current collector. In particular, near the anode surface we find an amorphized wispy silicon encased in a highly fluorinated matrix of electrolyte-reduction products. In contrast, closer to the current collector, the silicon retains more of its initial morphology and structure, suggesting the presence of isolated particles. The results show that the accessibility of active silicon to lithium ions varies across the anode matrix. Material and cell designs, which minimize electrode expansion resulting from the in-filling of pores with the solid electrolyte interphase (SEI), are needed to enhance anode homogeneity during the electrochemical cycling.

Anesthesiology Residency and Relationship Health: A Psychological Approach.

This article explores an often-untouched subject in anesthesiology residency: relationships. The authors examine the importance of fostering all types of relationships (eg, personal, professional, self) and the impact of the training process on relationships and total well-being. Common issues in relationships during anesthesiology residency are shared through real-life anecdotes from physicians who are currently in or have completed their residencies. Psychological principles including optimism bias, cognitive dissonance, social comparison, and self-efficacy are explored as contributing to dysfunction in relationships. Strategies are offered for each psychological domain as a resource for faculty and program leadership to improve the residency experience in anesthesiology.

Differences in Clinical and Functional Outcomes Between Osteochondral Allograft Transplantation and Autologous Chondrocyte Implantation for the Treatment of Focal Articular Cartilage Defects.

BACKGROUND: Articular cartilage pathology can result from a spectrum of origins, including trauma, osteochondritis dissecans, avascular necrosis, or degenerative joint disease. PURPOSE: To compare the differences in clinical and patient-reported outcomes after autologous chondrocyte implantation (ACI) versus osteochondral allograft transplantation (OCA) in patients with focal articular cartilage defects without underlying bone loss. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective review identified patients who underwent ACI or OCA between 2008 and 2016 for isolated grades 3 and 4 articular cartilage defects without underlying bone loss. Outcome measures included the Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR), International Knee Documentation Committee (IKDC) evaluation, and 12-Item Short Form Health Survey-Physical Component (SF-12-P) scores. Defect location, size, complications, and rate of subsequent surgery were determined. RESULTS: Overall, 148 patients were included: 82 (55%) underwent ACI and 66 (45%) underwent OCA. The mean age at the time of surgery was 31.2 years within the ACI cohort and 37.7 years within the OCA cohort (P < .001); the mean follow-up for both cohorts was 6.7 years (P = .902). Within the ACI group, 28 (34%) patients had multifocal defects, 21 (26%) had defects confined to the femoral condyles, and 33 (40%) had defects in the patellofemoral region. Within the OCA group, 23 (35%) patients had multifocal defects, 30 (46%) had confined femoral condyle lesions, and 13 (20%) had patellofemoral defects. When comparing by lesion location, there were no significant differences in KOOS JR, and IKDC scores between the ACI and OCA cohorts (P < .05). There was, however, a significant difference for SF-12-P scores for FDD trochlear lesions. In both cohorts, traumatic patellofemoral pathology demonstrated lower patient-reported outcomes and higher failure rates than degenerative lesions. The overall rate of failure, defined as graft failure with revision surgery and/or conversion to arthroplasty, was significantly greater in the OCA group (21% vs 4%; P = .002). CONCLUSION: Study results indicated that ACI provides similar outcomes to OCA with or without concomitant procedures for the treatment of symptomatic articular cartilage defects in all lesion locations and may have a lower revision rate for multifocal and condylar lesions.

Correction to "Facile Green Approach for Developing Electrochemically Reduced Graphene Oxide-Embedded Platinum Nanoparticles for Ultrasensitive Detection of Nitric Oxide".

[This corrects the article DOI: 10.1021/acsomega.0c05644.].

Dual-Salt Electrolytes to Effectively Reduce Impedance Rise of High-Nickel Lithium-Ion Batteries.

Simply mixing several lithium salts in one electrolyte to obtain blended salt electrolytes has been demonstrated as a promising strategy to formulate advanced electrolytes for lithium metal batteries (LMBs) and lithium-ion batteries (LIBs). In this study, we report the use of dual-salt electrolytes containing lithium hexafluorophosphate (LiPF6) and lithium difluorophosphate (LiDFP) in ethylene carbonate/ethyl methyl carbonate (EC/EMC) mixture and tested them in layered high-nickel LIB cells. LiNi0.94Co0.06O2 was synthesized through a coprecipitation method and was used as a representative high-nickel cathode for the U.S. DOE realizing next-generation cathode (RNGC) deep dive program. The ionic conductivity of dual-salt electrolytes can be maintained by controlling the amount of LiDFP. Techniques including 1H Nuclear Magnetic Resonance (NMR), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-mass spectrometry (ICP-MS), and differential voltage analysis (DVA) were used to understand the improved performance. The multifaceted benefits of using the dual-salt electrolytes include (1) reduced transesterification, (2) formation of a stable cathode electrolyte interface, and (3) mitigation of cathode degradation at high voltages, especially stabilization of oxide particles during the H2 ↔ H3 transformation.

Facile Green Approach for Developing Electrochemically Reduced Graphene Oxide-Embedded Platinum Nanoparticles for Ultrasensitive Detection of Nitric Oxide.

Nitric oxide (NO) plays a crucial and important role in cellular physiology and also acts as a signaling molecule for cancer in humans. However, conventional detection methods have their own limitations in the detection of NO at low concentrations because of its high reactivity and low lifetime. Herein, we report a strategy to fabricate Pt nanoparticle-decorated electrochemically reduced graphene oxide (erGO)-modified glassy carbon electrode (GCE) with efficiency to detect NO at a low concentration. For this study, Pt@erGO/GCE was fabricated by employing two different sequential methods [first GO reduction followed by Pt electrodeposition (SQ-I) and Pt electrodeposition followed by GO reduction (SQ-II)]. It was interesting to note that the electrocatalytic current response for SQ-I (184 µA) was ∼15 and ∼3 folds higher than those of the bare GCE (11.7 µA) and SQ-II (61.5 µA). The higher current response was mainly attributed to a higher diffusion coefficient and electrochemically active surface area. The proposed SQ-I electrode exhibited a considerably low LOD of 52 nM (S/N = 3) in a linear range of 0.25-40 µM with a short response time (0.7 s). In addition, the practical analytical applicability of the proposed sensor was also verified.

Hollow Polypyrrole Composite Synthesis for Detection of Trace-Level Toxic Herbicide.

In this work, we successfully demonstrated the fabrication of a chemical sensor for toxic 1,1-dimethyl-3-phenylurea (fenuron) by using a hollow polypyrrole composite film. Here, we studied the interaction between negatively charged phosphate anions enclosed in the film with positively charged nitrogen atoms present in the fenuron. The electrochemical response of the film was characterized by cyclic voltammetry in which, interestingly, we observed that the bigger alkyl aryl sulphonate ions were replaced by smaller phosphate ions with the creation of hollow/pore composite films. Confirmation for ion replacement in the film and porosity of the film were studied by elemental analysis and field emission scanning electron microscopy, respectively. The tuning of hydrophilic to hydrophobic nature of the hollow composite film was tested by the wettability test (contact angle measurement). The electrocatalytic materials, as well as the fenuron sensing conditions such as pH and film thickness, were wisely optimized on glassy carbon (GC) electrodes for better performance. We can enhance the fenuron sensitivity by over 5 times as compared to that on the GC substrate. To our knowledge, this is the first electrochemical fenuron sensor based on a hollow polymer film by differential pulse voltammetry which can detect lower concentrations and show quick response compared to other reports. This method has potential applications in the electrochemical sensing platform with good sensitive and selective analysis in agriculture groundwater samples.

In situ X-ray spatial profiling reveals uneven compression of electrode assemblies and steep lateral gradients in lithium-ion coin cells.

Coin cells are used extensively as test devices in battery research for evaluation of new materials and optimization of cycling protocols. In this study, in situ X-ray diffraction profilometry is used to characterize spatial distribution of the active materials, lithiation, and phase distribution in electrodes of NCM523/graphite coin cells. The X-ray data indicate uneven areal compression of the electrode assembly in such cells, which we trace to a specific design feature that leads to elastic deformation of a metal spacer. Steep lithiation gradients observed in the electrodes imply radially-dependent resistivity, for which uneven compression of the separator is a likely cause. Electrochemical model calculations suggest that variable porosity of the polymer separator would account for the salient features of spatial profiles observed in these coin cells.

Role of Sirtuins in Modulating Neurodegeneration of the Enteric Nervous System and Central Nervous System.

Neurodegeneration of the central and enteric nervous systems is a common feature of aging and aging-related diseases, and is accelerated in individuals with metabolic dysfunction including obesity and diabetes. The molecular mechanisms of neurodegeneration in both the CNS and ENS are overlapping. Sirtuins are an important family of histone deacetylases that are important for genome stability, cellular response to stress, and nutrient and hormone sensing. They are activated by calorie restriction (CR) and by the coenzyme, nicotinamide adenine dinucleotide (NAD+). Sirtuins, specifically the nuclear SIRT1 and mitochondrial SIRT3, have been shown to have predominantly neuroprotective roles in the CNS while the cytoplasmic sirtuin, SIRT2 is largely associated with neurodegeneration. A systematic study of sirtuins in the ENS and their effect on enteric neuronal growth and survival has not been conducted. Recent studies, however, also link sirtuins with important hormones such as leptin, ghrelin, melatonin, and serotonin which influence many important processes including satiety, mood, circadian rhythm, and gut homeostasis. In this review, we address emerging roles of sirtuins in modulating the metabolic challenges from aging, obesity, and diabetes that lead to neurodegeneration in the ENS and CNS. We also highlight a novel role for sirtuins along the microbiota-gut-brain axis in modulating neurodegeneration.

In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy.

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate multiple processes responsible for long-term performance decay. Given the complexity of physical processes occurring inside the cell, it is often challenging to achieve a full understanding of the root causes of this performance degradation. This difficulty arises in part from the fact that any electrochemical measurement of a battery will return the combined contributions of all components in the cell. Incorporation of a reference electrode can solve part of the problem, as it allows the electrochemical reactions of the cathode and the anode to be individually probed. A variation in the voltage range experienced by the cathode, for example, can indicate alterations in the pool of cyclable lithium ions in the full-cell. The structural evolution of the many interphases existing in the battery can also be monitored, by measuring the contributions of each electrode to the overall cell impedance. Such wealth of information amplifies the reach of diagnostic analysis in Li-ion batteries and provides valuable input to the optimization of individual cell components. In this work, we introduce the design of a test cell able to accommodate multiple reference electrodes, and present reference electrodes that are appropriate for each specific type of measurement, detailing the assembly process in order to maximize the accuracy of the experimental results.

In Situ Measurement of the Plane-Strain Modulus of the Solid Electrolyte Interphase on Lithium-Metal Anodes in Ionic Liquid Electrolytes.

We present an experimental approach for in situ measurement of elastic modulus of the solid electrolyte interphase (SEI), which is formed from reactions between a lithium thin-film [on a polydimethylsiloxane (PDMS) substrate] and a room-temperature ionic liquid (RTIL) electrolyte. The SEI forms under a state of compressive stress, which causes buckling of the sample surface. In situ atomic force microscopy is used to measure the dominant wavelength of the wrinkled surface topography. A mechanics analysis of strain-induced elastic buckling instability of a stiff thin film on a soft substrate is used to determine the plane strain modulus of the SEI from the measured wavelength. The measurements are performed for three RTIL electrolytes: 1-butyl 1-methylpiperidinium bis(trifluoromethylsulfonyl)imide (P14 TFSI) without any lithium salt, 1.0 M lithium bis(trifluoromethylsulfonyl)imide (Li TFSI) in P14 TFSI, and 1.0 M lithium bis(fluorosulfonyl)imide (Li FSI) in P14 TFSI to investigate the influence of lithium salts on the plane strain modulus of the SEI. The measurements yield plane-strain moduli of approximately 1.3 GPa for no-salt P14 TFSI and approximately 1.6 GPa for 1.0 M Li TFSI in P14 TFSI and 1.0 M Li FSI in P14 TFSI. The experimental technique presented here eliminates some of the uncertainties associated with traditional SEI mechanical characterization approaches and offers a platform to engineer an SEI with desired mechanical properties by approaches that include altering the electrolyte composition.

Unilateral Limb Thinning -Thinking Out of the Box.

We report an unusual presentation in a 9-year-old girl with unilateral circumferential thinning of the entire right upper limb without any other neurological deficit, with normal nerve conduction and electromyography initially thought of as a neurodegenerative disorder based on clinical presentation. Magnetic resonance imaging of the upper limb showed partial lipoatrophy with normal glucose metabolism and lipid profile and negativity for HIV and autoimmune disease (panniculitis) with no family history of similar disorder. Remember to think out of box before labeling neurodegenerative disease.

In vitro and in vivo activity of single and dual antimicrobial agents against KPC-producing Klebsiella pneumoniae.

Objectives: Options for treatment of infections due to KPC-producing Klebsiella pneumoniae are limited and combination therapy is often recommended. In this report, the in vitro and in vivo activity of potential therapeutic agents and combinations was assessed against four KPC-producing K. pneumoniae isolates. Methods: Using clinically relevant concentrations, time-kill experiments and the Galleria mellonella model of infection were used to examine the activity of polymyxin B, ceftazidime/avibactam, meropenem, rifampicin and amikacin alone and in combination. Results: Two K. pneumoniae isolates were resistant to polymyxin B and had ceftazidime/avibactam MICs of 8/4 mg/L. When ceftazidime/avibactam was combined with either amikacin or meropenem, synergy was observed in vitro, and these combinations were associated with improved survival in the in vivo model. Improved survival was also observed using higher doses of ceftazidime/avibactam. The other two K. pneumoniae isolates were susceptible to polymyxin B and had lower (1/4 mg/L) MICs of ceftazidime/avibactam. For these two isolates, bactericidal activity was observed in vitro at ceftazidime/avibactam concentrations four times the MIC. At one-quarter of the MIC, synergy was observed when ceftazidime/avibactam was combined with meropenem. In the in vivo model with the two susceptible isolates, improved survival rates were observed following therapy with ceftazidime/avibactam monotherapy. For all four isolates, polymyxin B with or without rifampicin or meropenem performed poorly in the in vivo model. Conclusions: Pending clinical studies, combining ceftazidime/avibactam with another agent (e.g. a carbapenem) should be considered when treating serious infections due to these pathogens, particularly for isolates with ceftazidime/avibactam MICs near the susceptibility breakpoint.

Patient education and anesthesia choice for total knee arthroplasty.

OBJECTIVES: Spinal anesthesia (SA) for Total Knee Arthroplasty (TKA) may be associated with better patients' outcomes. This study aims to assess the association between preoperative education about the advantage of SA over general anesthesia (GA) for TKA and the likelihood of patient choice of NA. METHODS: Patients undergoing unilateral primary TKA were identified. Type of anesthesia (GA or SA), attendance of the (joints class), patient demographics, ASA status, anticoagulation status, and diagnosis of back problems were recoded. Regression analysis was used to assess the association between the type of anesthesia and attendance of the joints class. RESULTS: 1010 patients were identified to have unilateral primary TKA. 31% of patients attended the joint class. Patients who attended the joints class were more likely to receive SA when compared to those who did not attend (OR=1.7, CI: 1.2-2.5, P=0.004) after adjusting for other variables. CONCLUSION: Preoperative education about advantages of SA may be associated with an increase in patients receiving SA for TKA. PRACTICE IMPLICATIONS: Increase in patients receiving SA for TKA may improve outcomes.