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Open Access Publications from the University of California

Scholarly Works (8 results)

  • Article
  • Peer Reviewed
Lawrence Berkeley National Laboratory (2010)
    Cover page: Magnetic vortex dynamics on a picosecond timescale in a hexagonal permalloy pattern
    • Article
    LBL Publications (2003)

    The electrochemical properties of LiFePO4 cathodes with different carbon contents were studied to find out the role of carbon as conductive additive. LiFePO4 cathodes containing from 0 percent to 12 percent of conductive additive (carbon black or mixture of carbon black and graphite) were cycled at different C rates. The capacity of LiFePO4 cathode increased, as conductive additive content increased. Carbon increased the utilization of active material and the electrical conductivity of electrode, but decreased volumetric capacity of electrode.

      Cover page: Effect of conductive additives in LiFePO4 cathode for lithium-ion batteries
      • Article
      • Peer Reviewed
      LBL Publications (2004)

      Anodes for lithium-ion cells were constructed from three types of natural graphite, two coated spherical and one flaky. Anode samples were compressed from 0 to 300 kg/cm2 and studied in half-cells to study the relations between anode density, SEI formation and anode cyclability. The C/25 formation of the SEI layer was found to depend on the nature of the graphite and the anode density. Compression of the uncoated graphite lead to an increased conductivity, but only slight improvements in the efficiency of the formation process. Compression of the anodes made from the amorphous-carbon-coated graphites greatly improved both the reversible capacity and first-cycle efficiency. In addition, the fraction of the irreversible charge associated with the surface of the graphite increased with compression, from both an increase in the electrolyte contact as well as compression of the amorphous layer. The cyclability of all of the anodes tended to improve with compression. This suggests that it is the improvement in the conductivity of the anode plays more of a role in the improvement in the cyclability than the formation process.

        Cover page: The effect of compression on natural graphite anode performance and matrix conductivity
        • Article
        LBL Publications (2002)
        LiFePO4/gel/natural graphite (NG) cells have been prepared and cycled under a fixed protocol for cycle and calendar life determination. Cell compression of 10 psi was found to represent an optimal balance between cell impedance and the first cycle losses on the individual electrodes with the gel electrolyte. Cells with a Li anode showed capacities of 160 and 78 mAh/g-LiFePO4 for C/25 and 2C discharge rates, respectively. Rapid capacity and power fade were observed in the LiFePO4/gel/NG cells during cycling and calanedar life studies. Diagnostic evaluations point to the consumption of cycleable Li though a side reaction as the reason for performance fade with minimal degradation of the individual electrodes.
          Cover page: LiFePO<sub>/gel/natural graphite cells for the BATT program</sub>
          • Article
          Lawrence Berkeley National Laboratory (2003)

          Lithium-ion cells, with graphite anodes and LiNi0.8Co0.15Al0.05O2 cathodes, were cycled for up to 1000 cycles over different ranges of SOC and temperatures. The decline in cell performance increases with the span of SOC and temperature during cycling. Capacity fade was caused by a combination of the loss of cycleable Li and degradation of the cathode. The room temperature anodes showed SEI compositions and degrees of graphite disorder that correlated with the extent of the Li consumption, which was linear in cell test time. TEM of the cathodes showed evidence of crystalline defects, though no major new phases were identified, consistent with XRD. No evidence of polymeric deposits on the cathode particles (FTIR) was detected although both Raman and TEM showed evidence of P-containing deposits from electrolyte salt degradation. Raman microscopy showed differences in relative carbon contents of the cycled cathodes, which is blamed for part of the cathode degradation.

            Cover page: Characterization of high-power lithium-ion cells-performance and diagnostic analysis
            • Article
            • Peer Reviewed
            UC San Francisco Previously Published Works (2013)

            Objectives

            Patients with psychiatric emergencies often spend excessive time in an emergency department (ED) due to limited inpatient psychiatric bed capacity. The objective was to compare traditional resident consultation with a new model (comanagement) to reduce length of stay (LOS) for patients with psychiatric emergencies. The costs of this model were compared to those of standard care.

            Methods

            This was a before-and-after study conducted in the ED of an urban academic medical center without an inpatient psychiatry unit from January 1, 2007, through December 31, 2009. Subjects were all adult patients seen by ED clinicians and determined to be a danger to self or others or gravely disabled. At baseline, psychiatry residents evaluated patients and made therapeutic recommendations after consultation with faculty. The comanagement model was fully implemented in September 2008. In this model, psychiatrists directly ordered pharmacotherapy, regularly monitored effects, and intensified efforts toward appropriate disposition. Additionally, increased attending-level involvement expedited focused evaluation and disposition of patients. An interrupted time series analysis was used to study the effects of this intervention on LOS for all psychiatric patients transferred for inpatient psychiatric care. Secondary outcomes included mean number of hours on ambulance diversion per month and the mean number of patients who left without being seen (LWBS) from the ED.

            Results

            A total of 1,884 patient visits were considered. Compared to the preintervention phase, median LOS for patients transferred for inpatient psychiatric care decreased by about 22% (p < 0.0005, 95% confidence interval [CI] = 15% to 28%) in the postintervention phase. Ambulance diversion hours increased by about 40 hours per month (p = 0.008, 95% CI = 11 to 69 hours) and the mean number of patients who LWBS decreased by about 26 per month (p = 0.106; 95% CI = -60 to 5.9 visits per month) in the postintervention phase.

            Conclusions

            A comanagement model was associated with a marked reduction in the LOS for this patient population.
              Cover page: Marked Reduction in Length of Stay for Patients With Psychiatric Emergencies After Implementation of a Comanagement Model
              • Article
              • Peer Reviewed
              LBL Publications (2022)
              Previous high-resolution angle-resolved photoemission (ARPES) studies of URu2Si2 have characterized the temperature-dependent behavior of narrow-band states close to the Fermi level (EF) at low photon energies near the zone center, with an emphasis on electronic reconstruction due to Brillouin zone folding. A substantial challenge to a proper description is that these states interact with other hole-band states that are generally absent from bulk-sensitive soft x-ray ARPES measurements. Here we provide a more global k-space context for the presence of such states and their relation to the bulk Fermi surface (FS) topology using synchrotron-based wide-angle and photon energy-dependent ARPES mapping of the electronic structure using photon energies intermediate between the low-energy regime and the high-energy soft x-ray regime. Small-spot spatial dependence, f-resonant photoemission, Si 2p core-levels, x-ray polarization, surface-dosing modification, and theoretical surface slab calculations are employed to assist identification of bulk versus surface state character of the EF-crossing bands and their relation to specific U- or Si-terminations of the cleaved surface. The bulk FS topology is critically compared to density functional theory (DFT) and to dynamical mean field theory calculations. In addition to clarifying some aspects of the previously measured high symmetry Γ, Z and X points, incommensurate 0.6a nested Fermi-edge states located along Z-N-Z are found to be distinctly different from the DFT FS prediction. The temperature evolution of these states above THO, combined with amore detailed theoretical investigation of this region, suggests a key role of the N-point in the hidden order transition.
                Cover page: Global perspectives of the bulk electronic structure of URu2Si2 from angle-resolved photoemission
                • Article
                • Peer Reviewed
                UC Davis Previously Published Works (2018)

                Background

                The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry.

                Methods and results

                A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up.

                Conclusion

                Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362.
                  Cover page: Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry
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