Structure and Thermodynamics of the Mixed Alkali Alanates

The thermodynamics and structural properties of the hexahydride alanates (M2M'AlH6) with the elpasolite structure have been investigated. A series of mixed alkali alanates (Na2LiAlH6, K2LiAlH6 and K2NaAlH6) were synthesized and found to reversibly absorb and desorb hydrogen without the need for a catalyst. Pressure-composition isotherms were measured to investigate the thermodynamics of the absorption and desorption reactions with hydrogen. Isotherms for catalyzed (4 mol% TiCl3) and uncatalyzed Na2LiAlH6 exhibited an increase in kinetics, but no change in the bulk thermodynamics with the addition of a dopant. A structural analysis using synchrotron x-ray diffraction showed that these compounds favor the Fm-3m space group with the smaller ion (M') occupying an octahedral site. These results demonstrate that appropriate cation substitutions can be used to stabilize or destabilize the material and may provide an avenue to improving the unfavorable thermodynamics of a number of materials with promising gravimetric hydrogen densities.Comment: 6 pages, 7 figures,3 tables, submitted to PR

Convergence of the Generalized Volume Averaging Method on a Convection-Diffusion Problem: A Spectral Perspective

A mixed formulation is proposed and analyzed mathematically for coupled convection-diffusion in heterogeneous medias. Transfer in solid parts driven by pure diffusion is coupled with convection-diffusion transfer in fluid parts. This study is carried out for translation-invariant geometries (general infinite cylinders) and unidirectional flows. This formulation brings to the fore a new convection-diffusion operator, the properties of which are mathematically studied: its symmetry is first shown using a suitable scalar product. It is proved to be self-adjoint with compact resolvent on a simple Hilbert space. Its spectrum is characterized as being composed of a double set of eigenvalues: one converging towards −∞ and the other towards +∞, thus resulting in a nonsectorial operator. The decomposition of the convection-diffusion problem into a generalized eigenvalue problem permits the reduction of the original three-dimensional problem into a two-dimensional one. Despite the operator being nonsectorial, a complete solution on the infinite cylinder, associated to a step change of the wall temperature at the origin, is exhibited with the help of the operator’s two sets of eigenvalues/eigenfunctions. On the computational point of view, a mixed variational formulation is naturally associated to the eigenvalue problem. Numerical illustrations are provided for axisymmetrical situations, the convergence of which is found to be consistent with the numerical discretization

The SafeD model : incorporating episodic disturbances and heuristic programming into forest management planning for the Applegate River Watershed, southwestern Oregon

A hybrid landscape optimization/simulation model called SafeD (Simulation and analysis of forests with episodic Disturbances) was built to address the needs of forest management planning in the Applegate River Watershed, southwestern Oregon (the Apple gate Project). There are two goals of the Applegate Project: 1) search for forest policies and practices that achieve goals set for the watershed; and 2) simulate forest condition over time (in the context of possible stochastic disturbances) considering the effects of different forest policies and practices. The SafeD model implements a four-stage process to guide management of the forested landscape to achieve specified goals over a planning horizon (40 years). The first stage develops stand prescriptions, for each recognized forest stand type and condition, which are designed to achieve specific stand goals. The second stage selects the prescription for each stand. The selection of prescriptions is accomplished using a heuristic programming technique, called the Great Deluge Algorithm, which is designed to find the "optimal" prescriptions that satisfy goals at the landscape level. In stage three the episodic disturbance processes are initiated. The episodic disturbances includes fire and insect attacks with weather patterns providing the stochastic element. Fire is spread using the FARSITE fire spread model with fine-resolution landscape data (25 meters x 25 meters). Insect attacks occur during drought periods in stands with excess basal area. Stage four is the re-analysis and re-selection of stand prescriptions (for the remaining time in the planning period) to accommodate for disturbances in stage three. A sample application of the SafeD model is presented here. Two landscape scenarios were developed. The first scenario contains two landscape goals. One goal is to produce the greatest amount of big trees (>=15" DBH) across the landscape. The second goal is actually a sub-watershed equivalent roaded acre (ERA) constraint. The second scenario presents a grow-only strategy to encapsulate the idea of leaving a landscape unmanaged. The results show several interesting conclusions which may have implications for forest management practices in the Applegate River Watershed. First, in order to maximize the number of big trees across the watershed timber harvesting will need to occur. Second, the effects of episodic insect disturbance negate the need for as much timber harvesting as would be projected without accounting for such disturbances. And third, fire plays a significantly less role, in regards to tree mortality, than insects will

Intensive Rotational Grazing Systems for Dairying in a Subtropical Environment: Animal, Plant, and Soil Responses

Forage species, stocking rate, and supplementation rate effects upon performance of lactating dairy cows were studied. Forage mass and nutritive value and nutrient concentration in shallow groundwater also were measured. Cows (n = 44) grazed bermudagrass (Cynodon dactylon) or rhizoma peanut (Arachis glabrata), stocked at 4.9 or 7.4 cows ha-1, and 2.5 or 4.9 cows ha-1, respectively. Pelleted concentrate:whole cottonseed (80:20) was offered twice daily post milking at 1 kg per 2 or 3 kg of daily milk production. Cows grazing rhizoma peanut produced more (P = .076) milk per day but had greater (P = .028) loss of body condition. Higher stocking rates caused greater (P \u3e .070) weight loss. Greater supplementation increased (P \u3c .05) production of milk, fat and protein, but also increased (P \u3c .044) weight and body condition losses. Higher stocking rates and lower supplementation reduced pasture (P \u3c .001) herbage mass. Rhizoma peanut herbage was higher in nutritive value than bermudagrass. Nutrient concentrations in shallow groundwater were not affected by treatments. Use of pasture for lactating cows has potential in Florida, but low milk production and loss of body condition during summer pose management challenges

Rhizoma Peanut Based Cropping Systems for Dairy Effluent Spray Fields

Cropping schemes that efficiently utilize nutrients applied in dairy waste effluent sprayfields is needed to avoid ground water contamination. Three 12 month cropping systems were grown under dairy waste effluent irrigation: 1) corn-forage sorghum-rye (C-FSR), 2) corn-rhizoma peanut-rye (C-RP-R), and 3) rhizoma peanutrye (RP-R). With an effluent N loading rate of 403 kg ha-1 yr-1, 2-yr mean DM yield was 30.7 Mg ha-1 yr-1 for the C-FS-R system, 26.2 for C-RP-R, and 17.9 for RP-R. Nitrogen concentration for C and FS ranged from 9 to 14 g kg-1 while RP ranged from 24 to 35. The higher N concentration in RP forage compensated for the lower DM yield of the RP-R system, resulting in the highest N removal of the 3 systems

Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Comparison

Knowledge of the relative stabilities of alane (AlH3) complexes with electron donors is essential for identifying hydrogen storage materials for vehicular applications that can be regenerated by off-board methods; however, almost no thermodynamic data are available to make this assessment. To fill this gap, we employed the G4(MP2) method to determine heats of formation, entropies, and Gibbs free energies of formation for thirty-eight alane complexes with NH3-nRn (R = Me, Et; n = 0-3), pyridine, pyrazine, triethylenediamine (TEDA), quinuclidine, OH2-nRn (R = Me, Et; n = 0-2), dioxane, and tetrahydrofuran (THF). Monomer, bis, and selected dimer complex geometries were considered. Using these data, we computed the thermodynamics of the key formation and dehydrogenation reactions that would occur during hydrogen delivery and alane regeneration, from which trends in complex stability were identified. These predictions were tested by synthesizing six amine-alane complexes involving trimethylamine, triethylamine, dimethylethylamine, TEDA, quinuclidine, and hexamine, and obtaining upper limits of delta G for their formation from metallic aluminum. Combining these computational and experimental results, we establish a criterion for complex stability relevant to hydrogen storage that can be used to assess potential ligands prior to attempting synthesis of the alane complex. Based on this, we conclude that only a subset of the tertiary amine complexes considered and none of the ether complexes can be successfully formed by direct reaction with aluminum and regenerated in an alane-based hydrogen storage system.Comment: Accepted by the Journal of Physical Chemistry

Evaluation of a Tennessee statewide initiative to reduce early elective deliveries using quasi-experimental methods

Abstract Background Concerted quality improvement (QI) efforts have been taken to discourage the practice of early elective deliveries (EEDs), but few studies have robustly examined the impact of directed QI interventions in reducing EED practices. Using quasi-experimental methods, we sought to evaluate the impact of a statewide QI intervention to reduce the practice of EEDs. Methods Retrospective cohort study of vital records data (2007 to 2013) for all singleton births occurring ≥36 weeks in 66 Tennessee hospitals grouped into three QI cohorts. We used interrupted-time series to estimate the effect of the QI intervention on the likelihood of an EED birth statewide, and by hospital cohort. We compared the distribution of hospital EED percentages pre- and post-intervention. Lastly, we used multivariable logistic regression to estimate the effect of QI interventions on maternal and infant outcomes. Results Implementation of the QI intervention was associated with significant declines in likelihood of EEDs immediately following the intervention (odds ratio, OR = 0.72; p < 0.001), but these results varied by hospital cohort. Hospital risk-adjusted EED percentages ranged from 1.6–13.6% in the pre-intervention period, which significantly declined to 2.2–9.6% in the post-intervention period (p < 0.001). The QI intervention was also associated with significant reductions in operative vaginal delivery and perineal laceration, and immediate infant ventilation, but increased NICU admissions. Conclusions A statewide QI intervention to reduce EEDs was associated with modest but significant declines in EEDs beyond concurrent and national trends, and showed mixed results in related infant and maternal outcomes.https://deepblue.lib.umich.edu/bitstream/2027.42/148522/1/12913_2019_Article_4033.pd

Harnessing a clinician-led governance model to overcome healthcare tribalism and drive innovation: a case study of Northumbria NHS Foundation Trust

Purpose Healthcare tribalism refers to the phenomenon through which different groups in a healthcare setting strictly adhere to their profession-based silo, within which they exhibit stereotypical behaviours. In turn, this can lead to deleterious downstream effects upon productivity and care delivered to patients. This study highlights a clinician-led governance model, implemented at a National Health Service (NHS) trust, to investigate whether it successfully overcame tribalism and helped drive innovation. Design/methodology/approach This was a convergent mixed-methods study including qualitative and quantitative data collected in parallel. Qualitative data included 27 semi-structured interviews with representatives from four professional groups. Quantitative data were collected through a verbally administered survey and scored on a 10-point scale. Findings The trust arranged its services under five autonomous business units, with a clinician and a manager sharing the leadership role at each unit. According to interviewees replies, this equivalent authority was cascaded down and enabled breaking down professional siloes, which in turn aided in the adoption of an innovative clinical model restructure. Practical implications This study contributes to the literature by characterizing a real-world example in which healthcare tribalism was mitigated while reflecting on the advantages yielded as a result. Originality/value Previous studies from all over the world identified major differences in the perspectives of different healthcare professional groups. In the United Kingdom, clinicians largely felt cut off from decision-making and dissatisfied with their managerial role. The study findings explain a governance model that allowed harmony and inclusion of different professions. Given the long-standing strains on healthcare systems worldwide, stakeholders can leverage the study findings for guidance in developing and implementing innovative managerial approaches

Novel multiple sclerosis susceptibility loci implicated in epigenetic regulation

We conducted a genome-wide association study (GWAS) on multiple sclerosis (MS) susceptibility in German cohorts with 4888 cases and 10,395 controls. In addition to associations within the major histocompatibility complex (MHC) region, 15 non-MHC loci reached genome-wide significance. Four of these loci are novel MS susceptibility loci. They map to the genes L3MBTL3, MAZ, ERG, and SHMT1. The lead variant at SHMT1 was replicated in an independent Sardinian cohort. Products of the genes L3MBTL3, MAZ, and ERG play important roles in immune cell regulation. SHMT1 encodes a serine hydroxymethyltransferase catalyzing the transfer of a carbon unit to the folate cycle. This reaction is required for regulation of methylation homeostasis, which is important for establishment and maintenance of epigenetic signatures. Our GWAS approach in a defined population with limited genetic substructure detected associations not found in larger, more heterogeneous cohorts, thus providing new clues regarding MS pathogenesis

The Forgotten Side of Partisanship: Negative Party Identification in Four Anglo-American Democracies

Early studies of electoral behavior proposed that party identification could be negative as well as positive. Over time, though, the concept became mostly understood as a positive construct. The few studies that took negative identification into account tended to portray it as a marginal factor that went “hand-in-hand” with positive preferences. Recent scholarship in psychology reaffirms, however, that negative evaluations are not simply the bipolar opposite of positive ones. This article considers negative party identification from this standpoint, and evaluates its impact in recent national elections in Australia, Canada, New Zealand, and the United States. Our findings highlight the autonomous power of negative partisanship. They indicate as well that ideology has an influence on both positive and negative partisan identification