Biexponential I = 3/2 Spin–Lattice Relaxation in the Solid State: Multiple-Quantum 7 Li NMR as a Probe of Fast Ion Dynamics

Spin–lattice relaxation measurements are used in 7Li NMR studies of materials of potential use in solid-state Li-ion batteries as a probe of ion mobility on a fast (nanosecond to picosecond) time scale. The relaxation behavior is often analyzed by assuming exponential behavior or, equivalently, a single T 1 time constant. However, the spin–lattice relaxation of spin I = 3/2 nuclei, such as 7Li, is in general biexponential; this is a fundamental property of I = 3/2 nuclei and unrelated to any compartmentalization within the solid. Although the possibility of biexponential 7Li (and other I = 3/2 nuclei) spin–lattice relaxation in the solid state has been noted by a number of authors, it can be difficult to observe unambiguously using conventional experimental NMR techniques, such as inversion or saturation recovery. In this work, we show that triple-quantum-filtered NMR experiments, as previously exploited in I = 3/2 NMR of liquids, can be used in favorable circumstances to observe and readily quantify biexponential 7Li spin–lattice relaxation in solids with high ion mobility. We demonstrate a triple-quantum-filtered inversion-recovery experiment on the candidate solid electrolyte material Li2OHCl at 325 K, which has previously been shown to exhibit fast ion mobility, and we also introduce a novel triple-quantum-filtered saturation-recovery experiment. The results of these solid-state NMR experiments are less straightforward than those in liquids as a consequence of the unwanted direct excitation of triple-quantum coherences by the weak (compared with the unaveraged 7Li quadrupolar interaction) pulses used, but we show that this unwanted excitation can be accounted for and, in the example shown here, does not impede the extraction of the two 7Li spin–lattice relaxation times

Exploration of the high temperature phase evolution of electrochemically modified Sc2(WO4)3via potassium discharge

The activation of Sc2(WO4)3via electrochemical discharge against potassium metal is investigated, as well as the subsequent thermal evolution of Sc2(WO4)3. On subsequent heating from 100 to 623 K the discharged electrode exhibits essentially the same thermal expansion as that of the pure powder. Between 673 and 973 K a trigonal K2WO4-type phase (P[3 with combining macron]m1) is formed. Variable-temperature X-ray diffraction data indicates that upon heating from 923 K–1023 K, this phase has a thermal expansion coefficient of −1.90(10) × 10−4 K−1

Maternal well-being and its association to risk of developmental problems in children at school entry

<p>Abstract</p> <p>Background</p> <p>Children at highest risk of developmental problems benefit from early identification and intervention. Investigating factors affecting child development at the time of transition to school may reveal opportunities to tailor early intervention programs for the greatest effectiveness, social benefit and economic gain. The primary objective of this study was to identify child and maternal factors associated with children who screened at risk of developmental problems at school entry.</p> <p>Methods</p> <p>An existing cohort of 791 mothers who had been followed since early pregnancy was mailed a questionnaire when the children were aged four to six years. The questionnaire included a screening tool for developmental problems, an assessment of the child's social competence, health care utilization and referrals, and maternal factors, including physical health, mental health, social support, parenting morale and sense of competence, and parenting support/resources.</p> <p>Results</p> <p>Of the 491 mothers (62%) who responded, 15% had children who were screened at high risk of developmental problems. Based on a logistic regression model, independent predictors of screening at high risk for developmental problems at age 5 were male gender (OR: 2.3; 95% CI: 1.3, 4.1), maternal history of abuse at pregnancy (OR: 2.4; 95% CI: 1.3, 4.4), and poor parenting morale when the child was 3 years old (OR: 3.9; 95% CI: 2.1, 7.3). A child with all of these risk factors had a 35% predicted probability of screening at high risk of developmental problems, which was reduced to 13% if maternal factors were favourable.</p> <p>Conclusions</p> <p>Risk factors for developmental problems at school entry are related to maternal well being and history of abuse, which can be identified in the prenatal period or when children are preschool age.</p

Comparison of performance of psychiatrists vs other outpatient physicians in the 2020 US Medicare Merit-Based Incentive Payment System

Importance: Medicare\u27s Merit-Based Incentive Payment System (MIPS) is a new, mandatory, outpatient value-based payment program that ties reimbursement to performance on cost and quality measures for many US clinicians. However, it is currently unknown how the program measures the performance of psychiatrists, who often treat a different patient case mix with different clinical considerations than do other outpatient clinicians. Objective: To compare performance scores and value-based reimbursement for psychiatrists vs other outpatient physicians in the 2020 MIPS. Design Setting and Participants: In this cross-sectional study, the Centers for Medicare & Medicaid Services Provider Data Catalog was used to identify outpatient Medicare physicians listed in the National Downloadable File between January 1, 2018, and December 31, 2020, who participated in the 2020 MIPS and received a publicly reported final performance score. Data from the 593 863 clinicians participating in the 2020 MIPS were used to compare differences in the 2020 MIPS performance scores and value-based reimbursement (based on performance in 2018) for psychiatrists vs other physicians, adjusting for physician, patient, and practice area characteristics. Exposures: Participation in MIPS. Main Outcomes and Measures: Primary outcomes were final MIPS performance score and negative (penalty), positive, and exceptional performance bonus payment adjustments. Secondary outcomes were scores in the MIPS performance domains: quality, promoting interoperability, improvement activities, and cost. Results: This study included 9356 psychiatrists (3407 [36.4%] female and 5 949 [63.6%] male) and 196 306 other outpatient physicians (69 221 [35.3%] female and 127 085 [64.7%] male) (data on age and race are not available). Compared with other physicians, psychiatrists were less likely to be affiliated with a safety-net hospital (2119 [22.6%] vs 64 997 [33.1%]) or a major teaching hospital (2148 [23.0%] vs 53 321 [27.2%]) and had lower annual Medicare patient volume (181 vs 437 patients) and mean patient risk scores (1.65 vs 1.78) ( Conclusions and Relevance: In this cross-sectional study that compared US psychiatrists with other outpatient physicians, psychiatrists had significantly lower 2020 MIPS performance scores, were penalized more frequently, and received fewer bonuses. Policy makers should evaluate whether current MIPS performance measures appropriately assess the performance of psychiatrists

Elucidating lithium-ion and proton dynamics in anti-perovskite solid electrolytes

All-solid-state Li-ion batteries are currently attracting considerable research attention as they present a viable opportunity for increased energy density and safety when compared to conventional liquid electrolyte-based devices. The Li-rich anti-perovskite Li3−xOHxCl has generated recent interest as a potential solid electrolyte material, but its lithium and proton transport capabilities as a function of composition are not fully characterised. In this work, we apply a combination of ab initio molecular dynamics and 1H, 2H and 7Li solid-state NMR spectroscopy to study the mobility of lithium ions and protons in Li3−xOHxCl. Our calculations predict a strongly exothermic hydration enthalpy for Li3OCl, which explains the ease with which this material absorbs moisture and the difficulty in synthesising moisture-free samples. We show that the activation energy for Li-ion conduction increases with increasing proton content. The atomistic simulations indicate fast Li-ion diffusion but rule out the contribution of long-range proton diffusion. These findings are supported by variable-temperature solid-state NMR experiments, which indicate localised proton motion and long-range Li-ion mobility that are intimately connected. Our findings confirm that Li3−xOHxCl is a promising solid electrolyte material for all-solid-state Li-ion batteries

Effects of Relaxation on Conversion Negative Electrode Materials for Li-Ion Batteries: A Study of TiSnSb Using 119Sn Mössbauer and 7Li MAS NMR Spectroscopies

Conversion materials were recently considered as plausible alternatives to conventional insertion negative electrode materials in lithium-ion batteries due to their large gravimetric and volumetric energy densities. The ternary alloy TiSnSb was recently proposed as a suitable negative electrode material due to its large capacity (550 mA h g–1) and rate capability over many cycles. TiSnSb has been investigated at the end of lithiation (discharge) using 119Sn Mössbauer and 7Li magic-angle spinning (MAS) NMR spectroscopies to determine the species formed, their relative stabilities and their behavior during relaxation. During discharge, TiSnSb undergoes a conversion reaction to produce a mixture of phases believed to consist of lithium antimonides, lithium stannides, and titanium metal. In situ 119Sn Mössbauer spectroscopy indicates the presence of Li7Sn2 at the end of discharge, while 7Li NMR experiments suggest the formation of two distinct Sn-containing species (tentatively assigned to Li7Sn2 and Li7Sn3), in addition to two Sb-containing species (tentatively assigned as Li3Sb and a non-stoichiometric phase of Li2Sb, Li2–xSb). To gain insight into the relative stabilities of the species formed, experiments have been completed under open circuit voltage conditions. A new Sn-based species has been identified via 119Sn Mössbauer spectroscopy at the end of relaxation. Similar changes are observed in the 7Li NMR spectra obtained during relaxation. The species created at the end of discharge are extremely unstable and spontaneously evolve towards delithiated phases. Surprisingly, it is possible to resume electrochemical cycling after relaxation. It is likely that this behavior can be extended to this family of electrode materials that undergo the conversion reaction

Perioperative Laboratory Abnormalities in Gynecologic Oncology Surgical Patients

Background: Laboratory blood testing incurs financial costs and the blood draws can increase discomfort, yet minimal data exists regarding routine testing in gynecologic oncology surgical patients. Additionally, an increasing number of gynecologic oncology surgeries are performed via a laparoscopic approach. Thus, further investigation into perioperative laboratory testing for gynecologic oncology patients is warranted. An increasing number of gynecologic oncology surgeries are performed via a laparoscopic approach. Thus, further investigation into perioperative laboratory testing for gynecologic oncology patients is warranted. Objective: The aims of this study were (1) to evaluate the frequency and etiology of perioperative laboratory test abnormalities in patients undergoing laparoscopic and laparotomy surgery in a gynecologic oncology service, and (2) to establish an evidence-based algorithm to reduce unnecessary laboratory testing. Materials and Methods: A single-institution retrospective study was completed, investigating laparoscopic and laparotomic surgeries over 4 years. Information on preoperative and postoperative laboratory data, surgical parameters, perioperative interventions, and patient demographics was collected. Quality-assurance data were reviewed. Data were tabulated and analyzed using Statistical Product and Service Solutions (SPSS) version 22. A Student's t-test was used to test for group differences for continuous variables with equal variance, the Mann-Whitney?U test for continuous variables when unequal variance was detected, and Pearson's ?2 was used to investigate categorical variables of interest. p-Values 98% of patients underwent at least one preoperative and postoperative laboratory test, totaling 8060 preoperative and 5784 postoperative results. The laparoscopy group was significantly less likely to have postoperative metabolic abnormalities or to undergo perioperative blood transfusion. Patients taking an angiotensin-converting-enzyme inhibitor, angiotensin-II?receptor blocker, or diuretic were significantly more likely to have elevated creatinine preoperatively (odds ratio [OR]: 5.0; p?Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140101/1/gyn.2015.0106.pd

Evaluating lithium diffusion mechanisms in the complex spinel Li2NiGe3O8

Lithium-ion diffusion mechanisms in the complex spinel Li2NiGe3O8 have been investigated using solid-state NMR, impedance, and muon spectroscopies. Partial occupancy of migratory interstitial 12d sites is shown to occur at lower temperatures than previously reported. Bulk activation energies for Li+ ion hopping range from 0.43 ± 0.03 eV for powdered samples to 0.53 ± 0.01 eV for samples sintered at 950 °C for 24 h, due to the loss of Li during sintering at elevated temperatures. A lithium diffusion coefficient of 3.89 × 10−12 cm2 s−1 was calculated from muon spectroscopy data for Li2NiGe3O8 at 300 K

Comprehensive Solid-State Characterization of Rare Earth Flouride Nanoparticles

The combination of multinuclear solid-state NMR spectroscopy and powder X-ray diffraction has been applied to characterize the octahedron-shaped crystalline nanoparticle products resulting from an inverse micelle synthesis. Rietveld refinements of the powder X-ray diffraction data from the nanoparticles revealed their general formula to be (H3O)Y3F10·xH2O. 1H magic-angle spinning (MAS) NMR experiments provided information on sample purity and served as an excellent probe of the zeolithic incorporation of atmospheric water. 19F MAS NMR experiments on a series of monodisperse nanoparticle samples of various sizes yielded spectra featuring three unique 19F resonances arising from three different fluorine sites within the (H3O)Y3F10·xH2O crystal structure. Partial removal of zeolithic water from the internal cavities and tunnels of the nanoparticles led to changes in the integrated peak intensities in the 19F MAS NMR spectra; the origin of this behavior is discussed in terms of 19F longitudinal relaxation. 19F–89Y variable-amplitude cross-polarization (VACP) NMR experiments on both stationary samples and samples under MAS conditions indicated that two distinct yttrium environments are present, and on the basis of the relative peak intensities, the population of one of the two sites is closely linked to the nanoparticle size. Both 19F MAS and 19F–89Y VACP/MAS experiments indicated small amounts of an impurity present in certain nanoparticles; these are postulated to be spherical amorphous YF3 nanoparticles. We discuss the importance of probing molecular-level structure in addition to microscopic structure and how the combination of these characterization methods is crucial for understanding nanoparticle design, synthesis, and application

The S troke H yperglycemia I nsulin N etwork E ffort ( SHINE ) trial protocol: a randomized, blinded, efficacy trial of standard vs. intensive hyperglycemia management in acute stroke

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102726/1/ijs12045.pd