146 research outputs found

    NMR and GC/MS investigation of the saturate and distillate fractions from the Cerro Negro heavy petroleum crude

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    Six fractions of the Cerro Negro heavy petroleum crude have been evaluated using nuclear magnetic resonance spectroscopy (NMR) and gas chromatography/mass spectrometry (GC/MS). The fractions include four saturated hydrocarbon distillate fractions distilling above 200/sup 0/C (200 to 425/sup 0/C (392 to 797/sup 0/F), 425 to 550/sup 0/C (797 to 1022/sup 0/F), 550 to 700/sup 0/C (1022 to 1292/sup 0/F), and >700/sup 0/C (>1292/sup 0/F)) and two distillate subfractions designated as <200/sup 0/C and >200/sup 0/C. The >700/sup 0/C and 550 to 700/sup 0/C saturated hydrocarbon fractions are not suited for analyses by combined GC/MS because their distillation ranges are higher than the upper limit of material that will elute from the gas chromatographic column. The /sup 1/H and /sup 13/C NMR spectral data for the 550 to 700/sup 0/C and >700/sup 0/C fractions indicate that normal and branched alkanes with an average carbon chainlength of C/sub 10/ are present but must be bonded to a larger molecular moiety based upon mass spectral evidence and boiling point considerations. Normal and branched alkanes were not detected in either 200 to 425/sup 0/C or 425 to 550/sup 0/C samples at concentrations of 0.01% by weight. NMR data for the 200 to 425/sup 0/C fraction give no indication of normal alkanes with C chainlengths >9. Branched alkanes possibly of the isoprenoid-like structure are present. The average molecular structural representation is an alkyl-substituted dicyclic alkane. Average molecular structural representation for the 425 to 550/sup 0/C fraction is also an alkyl-substituted dicyclic alkane. However, at least one of the alkyl substituents has a chainlength >10. Both normal and branched alkanes of C/sub 7-12/ were detected in the <200/sup 0/C subfraction. Alkanes of C/sub 12-31/ were in the >200/sup 0/C sample. /sup 1/H and /sup 13/C spectra for both subfractions indicate similar chemical composition. 12 refs., 6 figs., 8 tabs

    Hydrochloric Acid Infusion for the Treatment of Metabolic Alkalosis in Surgical Intensive Care Unit Patients

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    Background: Older reports of use of hydrochloric acid (HCl) infusions for treatment of metabolic alkalosis document variable dosing strategies and risk. Objectives: This study sought to characterize use of HCl infusions in surgical intensive care unit patients for the treatment of metabolic alkalosis. Methods: This retrospective review included patients who received a HCl infusion for \u3e8 hours. The primary end point was to evaluate the utility of common acid-base equations for predicting HCl dose requirements. Secondary end points evaluated adverse effects, efficacy, duration of therapy, and total HCl dose needed to correct metabolic alkalosis. Data on demographics, potential causes of metabolic alkalosis, fluid volume, and duration of diuretics as well as laboratory data were collected. Results: A total of 30 patients were included, and the average HCl infusion rate was 10.5 ± 3.7 mEq/h for an average of 29 ± 14.6 hours. Metabolic alkalosis was primarily diuretic-induced (n = 26). Efficacy was characterized by reduction in the median total serum CO2 from 34 to 27 mM/L (P \u3c 0.001). The change in chloride ion deficit and change in apparent strong ion difference (SIDa) were not correlated with total HCl administered. There were no documented serious adverse effects related to HCl infusions. Conclusion: HCl was effective for treating metabolic alkalosis, and no serious adverse events were seen. In this clinical setting, the baseline chloride ion deficit and SIDa were not useful for prediction of total HCl dose requirement, and serial monitoring of response is recommended

    A Preliminary Assessment of Rotavirus Vaccine Effectiveness in Zambia

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    BACKGROUND: Diarrhea is the third leading cause of child death in Zambia. Up to one-third of diarrhea cases resulting in hospitalization and/or death are caused by vaccine-preventable rotavirus. In January 2012, Zambia initiated a pilot introduction of the Rotarix live, oral rotavirus vaccine in all public health facilities in Lusaka Province. METHODS: Between July 2012 and October 2013, we conducted a case-control study at 6 public sector sites to estimate rotavirus vaccine effectiveness (VE) in age-eligible children presenting with diarrhea. We computed the odds of having received at least 1 dose of Rotarix among children whose stool was positive for rotavirus antigen (cases) and children whose stool was negative (controls). We adjusted the resulting odds ratio (OR) for patient age, calendar month of presentation, and clinical site, and expressed VE as (1 - adjusted OR) × 100. RESULTS: A total of 91 rotavirus-positive cases and 298 rotavirus-negative controls who had under-5 card-confirmed vaccination status and were ≥6 months of age were included in the case-control analysis. Among rotavirus-positive children who were age-eligible to be vaccinated, 20% were hospitalized. Against rotavirus diarrhea of all severity, the adjusted 2-dose VE was 26% (95% confidence interval [CI], -30% to 58%) among children ≥6 months of age. VE against hospitalized children ≥6 months of age was 56% (95% CI, -34% to 86%). CONCLUSIONS: We observed a higher point estimate for VE against increased severity of illness compared with milder disease, but were not powered to detect a low level of VE against milder disease

    Multicenter prevalence of anaphylaxis in clinic-based oral food challenges

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    Background Although previous single-center studies report the rate of anaphylaxis for oral food challenges (OFCs) as 9% to 11%, little is known regarding the epidemiology of clinical OFCs across multiple centers in the United States. Objective To examine the epidemiology, symptoms, and treatment of clinical low-risk OFCs in the nonresearch setting. Methods Data were obtained from 2008 to 2013 through a physician survey in 5 food allergy centers geographically distributed across the United States. Allergic reaction rates and the association of reaction rates with year, hospital, and demographics were determined using a linear mixed model. Meta-analysis was used to pool the proportion of reactions and anaphylaxis with inverse-variance weights using a random-effects model with exact confidence intervals (CIs). Results A total of 6,377 OFCs were performed, and the pooled estimate of anaphylaxis was 2% (95% CI, 1%-3%). The rate of allergic reactions was 14% (95% CI, 13%-16%) and was consistent during the study period (P = .40). Reaction rates ranged from 13% to 33%. Males reacted 16% more frequently than females (95% CI, 4%-37.5%; P = .04). Foods challenged in 2013 varied geographically, with peanut as the most challenged food in the Northeast, Midwest, and West and egg as the most challenged in the South. Conclusion As the largest national survey of allergic reactions of clinical open OFCs in a nonresearch setting in the United States, this study found that performing clinical nonresearch open low-risk OFCs results in few allergic reactions, with 86% of challenges resulting in no reactions and 98% without anaphylaxis

    Critical Language and Discourse Awareness in Management Education

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    Communication and, through it, language have become key elements of business and organizational life. How organizations interact within their walls and with the outside world fundamentally affects business processes, creating organizational culture, shaping public perceptions, and influencing consumer choices. This essay calls for a greater acknowledgment of language and communication and suggests that management educators may want to review how they are incorporated in management education curricula. Expanding on the skill-based approach typically adopted in business school classes, the essay points to the utility of exposing business students to the dual function of language as a means of doing work and as a social action that constitutes social reality. Drawing on examples from scholarship in linguistics and discourse analysis, the essay demonstrates that the ability to notice, identify, and reflect on linguistic and discourse practices is a crucial managerial skill. Nurturing such analytical and thinking skills enables people to become not only better communicators but also critical thinkers able to understand and challenge when social control, power, or injustice is enacted in organizations

    Investigation into pedestrian exposure to near-vehicle exhaust emissions

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    <p>Abstract</p> <p>Background</p> <p>Inhalation of diesel particulate matter (DPM) is known to have a negative impact on human health. Consequently, there are regulations and standards that limit the maximum concentrations to which persons may be exposed and the maximum concentrations allowed in the ambient air. However, these standards consider steady exposure over large spatial and time scales. Due to the nature of many vehicle exhaust systems, pedestrians in close proximity to a vehicle's tailpipe may experience events where diesel particulate matter concentrations are high enough to cause acute health effects for brief periods of time.</p> <p>Methods</p> <p>In order to quantify these exposure events, instruments which measure specific exhaust constituent concentrations were placed near a roadway and connected to the mouth of a mannequin used as a pedestrian surrogate. By measuring concentrations at the mannequin's mouth during drive-by events with a late model diesel truck, a representative estimate of the exhaust constituent concentrations to which a pedestrian may be exposed was obtained. Typical breathing rates were then multiplied by the measured concentrations to determine the mass of pollutant inhaled.</p> <p>Results</p> <p>The average concentration of diesel particulate matter measured over the duration of a single drive-by test often exceeded the low concentrations used in human clinical studies which are known to cause acute health effects. It was also observed that higher concentrations of diesel particulate matter were measured at the height of a stroller than were measured at the mouth of a mannequin.</p> <p>Conclusion</p> <p>Diesel particulate matter concentrations during drive-by incidents easily reach or exceed the low concentrations that can cause acute health effects for brief periods of time. For the case of a particularly well-tuned late-model year vehicle, the mass of particulate matter inhaled during a drive-by incident is small compared to the mass inhaled daily at ambient conditions. On a per breath basis, however, the mass of particulate matter inhaled is large compared to the mass inhaled at ambient conditions. Finally, it was determined that children, infants, or people breathing at heights similar to that of a passing vehicle's tailpipe may be exposed to higher concentrations of particulate matter than those breathing at higher locations, such as adults standing up.</p

    Integrating Human Indoor Air Pollutant Exposure within Life Cycle Impact Assessment

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    Neglecting health effects from indoor pollutant emissions and exposure, as currently done in Life Cycle Assessment (LCA), may result in product or process optimizations at the expense of workers’ or consumers’ health. To close this gap, methods for considering indoor exposure to chemicals are needed to complement the methods for outdoor human exposure assessment already in use. This paper summarizes the work of an international expert group on the integration of human indoor and outdoor exposure in LCA, within the UNEP/SETAC Life Cycle Initiative. A new methodological framework is proposed for a general procedure to include human-health effects from indoor exposure in LCA. Exposure models from occupational hygiene and household indoor air quality studies and practices are critically reviewed and recommendations are provided on the appropriateness of various model alternatives in the context of LCA. A single-compartment box model is recommended for use as a default in LCA, enabling one to screen occupational and household exposures consistent with the existing models to assess outdoor emission in a multimedia environment. An initial set of model parameter values was collected. The comparison between indoor and outdoor human exposure per unit of emission shows that for many pollutants, intake per unit of indoor emission may be several orders of magnitude higher than for outdoor emissions. It is concluded that indoor exposure should be routinely addressed within LCA
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