322 research outputs found

    SBE-type metal-substituted aluminophosphates: detemplation and coordination chemistry

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    The detemplation process in Me-SBE (Me = Co^2+, Mg^2+, and Mn^2+) aluminophosphates was studied to elucidate materials stability and framework characteristics. In addition, the hydrothermal synthesis conditions were optimized to obtain materials with minimal phase impurities. This was accomplished by means of decreasing reaction temperature and increasing aging periods. Scanning electron microscopy analysis of the Mg- and Mn-SBE as-synthesized samples revealed square plates with truncated corner morphologies grown in aggregated fashion and contrasting with the previously reported hexagonal platelike morphology of Co-SBE. Cautious detemplation in vacuum, using an evacuation rate of 10 mmHg/s and a temperature of 648 K, resulted in surface areas of about 700, 500, and 130 m^2/g for Mg-, Co-, and Mn-SBE, respectively. Thermal gravimetric analysis and in situ high-temperature powder X-ray diffraction analyses indicate the frameworks for all of the SBE variants experienced collapse upon treatment with helium at temperatures above 700 K and subsequently formed an aluminophosphate trydimite dense phase. Detemplation in air at all times resulted in framework destruction during detemplation. In situ differential scanning calorimetry−powder X-ray diffraction data showed that the SBE frameworks experience breathing modes related to specific endothermic and exothermic scenarios during air treatment. Decomposition and elimination of the organic template during vacuum treatment was verified by Fourier transform infrared spectroscopy. X-ray photoelectron spectroscopy revealed that most of the Co atoms in vacuum-treated samples are in tetrahedral coordination, while the Mn atoms exhibit various coordination states. Ultraviolet-visible, electron paramagnetic resonance, and magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy corroborated the latter result in addition to providing evidence for the formation of Mn extra framework species. ^(27)Al MAS NMR spectra for vacuum-detemplated Mg-SBE samples prior to and after dehydration confirmed the reversible formation of aluminum octahedral sites. This, however, did not affect the porous nature of detemplated Mg-SBE samples as these are capable of adsorbing 19 water molecules per super cage at 298 K

    Scaling Up

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    Moments of crisis require big, bold ideas. In this chapter we will zoom out of our close examination of the Northern Manhattan Community Voices Collaborative experience to propose ways to scale up the things that worked for us in order to make them applicable at a national level. With this chapter we honor the intent of the W. K. Kellogg Foundation in its support of learning laboratories across the nation. Our goal is to contribute to the collective dialogue on how to improve the health care system. Specifically, we propose that making a healthier nation and reducing health care costs will require more than simply moving toward universal health coverage — which is essential — or implementing technologies to digitalize medical records — which is useful. As epidemiologists would say, those things are necessary but not sufficient to overhaul our ailing health care system. Instead, we propose to reduce health care costs and improve health care access by implementing a national prevention program through collaboration based on a new health compact with society — one that delivers on the promise of justice for all and (paraphrasing our forefathers/mothers) the pursuit of health

    Rare top quark decay t --> u_1 \bar{u}_2 u_2 in the standard model

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    The one-loop induced top quark decay tu1uˉ2u2t\to u_1\bar{u}_2u_2 (ui=u,cu_i=u,c) is calculated in the context of the standard model. The dominant contribution to this top quark decay arises from the Feynman diagrams induced by the off-shell tu1gtu_1g^* vertex, whereas the box diagrams are negligibly small. In contrast with the on-shell tu1gtu_1g vertex, which only gives rise to a pure dipolar effect, the off-shell tu1gtu_1g^* coupling also involves a monopolar term, which gives a larger contribution than the dipolar one. It is found that the branching ratio for the three-body decay tu1uˉ2u2t\to u_1\bar{u}_2u_2 is about of the same order of magnitude of the two-body decay tu1gt\to u_1 g, the latter being slightly larger, which stems from the fact that the three-body decay is dominated by a monopolar term.Comment: 8 pages, 3 figures, branching ratio is evaluated using the running quark masses at the top quark mass scale, results and conclusion changes slightly, new results agree with those presented in hep-ph/0601151, missing references are adde

    External stimuli help restore post-partum ovarian activity in Pelibuey sheep

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    Post-partum anestrus is a problem on farms, and its duration depends on the frequency and intensity of suckling which affects reproduction and production efficiency to become a determining economic factor. The aim of this study was to determine the post-partum reproductive response in ewe to a "male effect" with an ovulation induction protocol of five days using progesterone and the application of a metabolic restorative (MR; Metabolase ®). One hundred and twenty females were randomly assigned to one of four treatments: T1: Continuous suckling (CS; n = 29), T2: CS + MR (n = 29), T3: CS + Male Effect (ME; n = 32), and T4: CS + MR + ME. The percentage of females in ovulation, weight changes among females and lambs, the onset of estrus, calving, fecundity, and prolificacy were also determined. The ovulation percentage was higher in CS + ME and CS + MR + ME (75.0 and 73.3%) than in the other treatments. Weight changes in females and lambs were different among periods. The onset of estrus was similar for CS and CS + MR (25.9 ± 1.9 and 25.7 ± 0.7 h, respectively). The calving percentage was higher for CS + MR (86.2%) than other treatments. Male presence positively affected the postpartum cyclic ovarian re-establishment and the metabolic restorative could even improve the fertility of hair ewes in continuous suckling with similar hormone protocolKeywords: Male effect, metabolic stimulation, post-partum anestru

    The \gamma \gamma \to \phi_i\phi_j processes in the type-III two-Higgs-doublet model

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    We discuss the implications of assuming a four-zero Yukawa texture and a general Higgs potential for the production of neutral Higgs boson pairs at \gamma \gamma colliders through the \gamma \gamma \to \phi_i\phi_j (\phi_i = h, H, A) reaction within the context of the two Higgs doublet model type III. Exact analytical expressions for the \gamma \gamma \to \phi_i\phi_j reaction are presented. The use of a nonlinear R_\xi-gauge, which considerably simplifies the loop calculations and renders compact analytical expressions, is stressed. We show that these processes are very sensitive to a general structure of the Higgs potential that impact the triple and quartic couplings of the scalar sector. We present results for scenarios of the parameters of the model that are still consistent with current experimental constraints. It is found that the cross sections for the \gamma \gamma \to \phi_i\phi_j processes can be up to two orders of magnitude larger than those gotten in 2HDM type I and type II. The possibility of a light CP--scalar is also studied

    Primer registro de la cojolita (Penelope purpurascens) en el estado de Guanajuato, México

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    -Aquí se informa sobre el registro de la cojolita en la Reserva de Biosfera Sierra Gorda de Guanajuato, el cual es el registro más central para esa latitud y el primero para el estado. Esta especie fue registrada fotográfícamente en un bosque de encino. La presencia de esta especie enfatiza la necesidad de continuar realizando inventarios biológicos en esta Reserva de la Biosfer

    Efficacy of β-lactam/β-lactamase inhibitors to treat extended-spectrum beta-lactamase-producing Enterobacterales bacteremia secondary to urinary tract infection in kidney transplant recipients

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    Background Whether active therapy with β-lactam/β-lactamase inhibitors (BLBLI) is as affective as carbapenems for extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) bloodstream infection (BSI) secondary to urinary tract infection (UTI) in kidney transplant recipients (KTRs) remains unclear. Methods We retrospectively evaluated 306 KTR admitted to 30 centers from January 2014 to October 2016. Therapeutic failure (lack of cure or clinical improvement and/or death from any cause) at days 7 and 30 from ESBL-E BSI onset was the primary and secondary study outcomes, respectively. Results Therapeutic failure at days 7 and 30 occurred in 8.2% (25/306) and 13.4% (41/306) of patients. Hospital-acquired BSI (adjusted OR [aOR]: 4.10; 95% confidence interval [CI]: 1.50-11.20) and Pitt score (aOR: 1.47; 95% CI: 1.21-1.77) were independently associated with therapeutic failure at day 7. Age-adjusted Charlson Index (aOR: 1.25; 95% CI: 1.05-1.48), Pitt score (aOR: 1.72; 95% CI: 1.35-2.17), and lymphocyte count ≤500 cells/μL at presentation (aOR: 3.16; 95% CI: 1.42-7.06) predicted therapeutic failure at day 30. Carbapenem monotherapy (68.6%, primarily meropenem) was the most frequent active therapy, followed by BLBLI monotherapy (10.8%, mostly piperacillin-tazobactam). Propensity score (PS)-adjusted models revealed no significant impact of the choice of active therapy (carbapenem-containing vs any other regimen, BLBLI- vs carbapenem-based monotherapy) within the first 72 hours on any of the study outcomes. Conclusions Our data suggest that active therapy based on BLBLI may be as effective as carbapenem-containing regimens for ESBL-E BSI secondary to UTI in the specific population of KTR. Potential residual confounding and unpowered sample size cannot be exclude
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