Between June 2010 and June 2011, the National Institute of Standards and Technology (NIST) gravimetrically prepared a suite of 20 carbon dioxide (CO2) in air primary standard mixtures (PSMs). Ambient mole fraction levels were obtained through six levels of dilution beginning with pure (99.999%) CO2. The sixth level covered the ambient range from 355 to 404 μmol/mol. This level will be used to certify cylinder mixtures of compressed dry whole air from both the northern and southern hemispheres as NIST standard reference materials (SRMs). The first five levels of PSMs were verified against existing PSMs in a balance of air or nitrogen with excellent agreement observed (the average percent difference between the calculated and analyzed values was 0.002%). After the preparation of a new suite of PSMs at ambient level, they were compared to an existing suite of PSMs. It was observed that the analyzed concentration of the new PSMs was less than the calculated gravimetric concentration by as much as 0.3% relative. The existing PSMs had been used in a Consultative Committee for Amount of Substance-Metrology in Chemistry Key Comparison (K-52) in which there was excellent agreement (the NIST-analyzed value was -0.09% different from the calculated value, while the average of the difference for all 18 participants was -0.10%) with those of other National Metrology Institutes and World Meteorological Organization designated laboratories. In order to determine the magnitude of these losses at the ambient level, a series of "daughter/mother" tests were initiated and conducted in which the gas mixture containing CO2 from a "mother" cylinder was transferred into an evacuated "daughter" cylinder. These cylinder pairs were then compared using cavity ring-down spectroscopy under high reproducibility conditions (the average percent relative standard deviation of sample response was 0.02). A ratio of the daughter instrument response to the mother response was calculated, with the resultant deviation from unity being a measure of the CO2 loss or gain. Cylinders from three specialty gas vendors were tested to find the appropriate cylinder in which to prepare the new PSMs. All cylinders tested showed a loss of CO2, presumably to the walls of the cylinder. The vendor cylinders exhibiting the least loss of CO2 were then purchased to be used to gravimetrically prepare the PSMs, adjusting the calculated mole fraction for the loss bias and an uncertainty calculated from this work.
CCQM-K120.a comparison involves preparing standards of carbon dioxide in air which are fit for purpose for the atmospheric monitoring community, with stringent requirements on matrix composition and measurement uncertainty of the CO2 mole fraction. This represents an analytical challenge and is therefore considered as a Track C comparison. The comparison will underpin CMC claims for CO2 in air for standards and calibrations services for the atmospheric monitoring community, matrix matched to real air, over the mole fraction range of 250 μmol/mol to 520 μmol/mol. CCQM-K120.b comparison tests core skills and competencies required in gravimetric preparation, analytical certification and purity analysis. It is considered as a Track A comparison. It will underpin CO2 in air and nitrogen claims in a mole fraction range starting at the smallest participant's reported expanded uncertainty and ending at 500 mmol/mol. Participants successful in this comparison may use their result in the flexible scheme and underpin claims for all core mixtures This study has involved a comparison at the BIPM of a suite of 44 gas standards prepared by each of the participating laboratories. Fourteen laboratories took part in both comparisons (CCQM-K120.a, CCQM-K120.b) and just one solely in the CCQM-K120.b comparison. The standards were sent to the BIPM where the comparison measurements were performed. Two measurement methods were used to compare the standards, to ensure no measurement method dependant bias: GC-FID and FTIR spectroscopic analysis corrected for isotopic variation in the CO2 gases, measured at the BIPM using absorption laser spectroscopy. Following the advice of the CCQM Gas Analysis Working Group, results from the FTIR method were used to calculate the key comparison reference values. KEY WORDS FOR SEARCH FTIR, CO2, GC-FID, Carbon dioxide at background level, Carbon dioxide at urban level, Delta Ray, CO2 gas standards Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Introduction: Standardization of interfacility transport handover is associated with improved shared mental model development, efficiency, and teaming. We sought to build upon previously published data by evaluating 1-year follow-up data, assessing face-validity, and describing sustainability. Methods: We performed a pre-post, retrospective cohort study in a stand-alone, tertiary, pediatric referral center for children 0–18 years of age transported to our pediatric intensive care unit, neonatal intensive care unit, or emergency department from October 2016 to November 2017. Handover was standardized using multidisciplinary checklists, didactics, and simulation. Data were collected for three 8-week periods (preintervention, postintervention, and 1-year follow-up). Outcomes included shared mental model index (shared mental model congruence expressed as an index, percent congruence regarding healthcare data), teaming data (efficiency, attendance, interruptions, interdependence), and face validity (5-point, Likert scale questionnaires). Statistics included 1-way analysis of variance, Kruskal-Wallis, chi-square, and descriptive statistics. Results: One hundred forty-eight handovers (50 preintervention, 50 postintervention, and 48 at 1-year) were observed in the emergency department (41%), pediatric intensive care unit (45%), and neonatal intensive care unit (14%). No differences were noted in demographics, diagnoses, PIM-3-ROM, length of stay, mortality, ventilation, or vasoactive use. Sustained improvements were observed in shared mental model congruence expressed as an index (38% to 82%), physician attendance (76% to 92%), punctuality (91.5% to 97.5%), interruptions (40% to 10%), provision of anticipatory guidance (42% to 85%), and handover summarization (42% to 85%, all P < 0.01). Efficiency was maintained throughout (mean duration 4.5 ± 2.1 minutes). Face validity data revealed handover satisfaction, effective communication, and perceived professionalism. Conclusions: Enhancements in teaming, shared mental model development, and face validity were achieved and sustained 1-year following handover standardization with only minimal reeducation during the study period.
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