Indirect H2O2 synthesis without H2.

Industrial hydrogen peroxide (H2O2) is synthesized using carbon-intensive H2 gas production and purification, anthraquinone hydrogenation, and anthrahydroquinone oxidation. Electrochemical hydrogenation (ECH) of anthraquinones offers a carbon-neutral alternative for generating H2O2 using renewable electricity and water instead of H2 gas. However, the H2O2 formation rates associated with ECH are too low for commercialization. We report here that a membrane reactor enabled us to electrochemically hydrogenate anthraquinone (0.25 molar) with a current efficiency of 70% at current densities of 100 milliamperes per square centimeter. We also demonstrate continuous H2O2 synthesis from the hydrogenated anthraquinones over the course of 48 h. This study presents a fast rate of electrochemically-driven anthraquinone hydrogenation (1.32 ± 0.14 millimoles per hour normalized per centimeter squared of geometric surface of electrode), and provides a pathway toward carbon-neutral H2O2 synthesis.

Endergonic Hydrogenation at Ambient Conditions Using an Electrochemical Membrane Reactor.

Here, we determine how the hydrogen loading (x) of an electrochemical palladium membrane reactor (ePMR) varies with electrochemical conditions (e.g., applied current density, electrolyte concentration). We detail how x influences the thermodynamic driving force of an ePMR. These studies are accomplished by measuring the fugacity (P) of hydrogen desorbing from the palladium-hydrogen membrane and subsequently relating P to pressure-composition isotherms to determine x. We find that x increases with both applied current density and electrolyte concentration, but plateaus at a loading of x ≅ 0.92 in 1.0 M H2SO4 at -200 mA·cm-2. The validity of the fugacity measurements is supported experimentally and computationally by: (a) electrochemical hydrogen permeation studies; and (b) a palladium-hydrogen porous flow finite element analysis (FEA) model. Both (a) and (b) agree with the fugacity measurements on the following x-dependent properties of the palladium-hydrogen system during electrolysis: (i) the onset for spontaneous hydrogen desorption; (ii) the point of steady-state hydrogen loading; and (iii) the function describing hydrogen desorption between (i) and (ii). We proceed to detail how x defines the free energy of palladium-hydrogen alloy formation (ΔG(x)PdH), which is a descriptor for the thermodynamic driving force of hydrogenation at the PdHx surface of an ePMR. A maximum value ΔGPdH of 11 kJ·mol-1 is observed, suggesting that an ePMR is capable of driving endergonic hydrogenation reactions. We empirically demonstrate this capability by reducing carbon dioxide to formate (ΔGCO2/HCO2H = 3.4 kJ·mol-1) at ambient conditions and neutral pH.

Bioelectrocatalysis with a palladium membrane reactor.

Enzyme catalysis is used to generate approximately 50,000 tons of value-added chemical products per year. Nearly a quarter of this production requires a stoichiometric cofactor such as NAD+/NADH. Given that NADH is expensive, it would be beneficial to regenerate it in a way that does not interfere with the enzymatic reaction. Water electrolysis could provide the proton and electron equivalent necessary to electrocatalytically convert NAD+ to NADH. However, this form of electrocatalytic NADH regeneration is challenged by the formation of inactive NAD2 dimers, the use of high overpotentials or mediators, and the long-term electrochemical instability of the enzyme during electrolysis. Here, we show a means of overcoming these challenges by using a bioelectrocatalytic palladium membrane reactor for electrochemical NADH regeneration from NAD+. This achievement is possible because the membrane reactor regenerates NADH through reaction of hydride with NAD+ in a compartment separated from the electrolysis compartment by a hydrogen-permselective Pd membrane. This separation of the enzymatic and electrolytic processes bypasses radical-induced NAD+ degradation and enables the operator to optimize conditions for the enzymatic reaction independent of the water electrolysis. This architecture, which mechanistic studies reveal utilizes hydride sourced from water, provides an opportunity for enzyme catalysis to be driven by clean electricity where the major waste product is oxygen gas.

An environmental scan of emergency medicine research support, training, and infrastructure across Canada.

OBJECTIVE: Our study objective was to describe the Canadian emergency medicine (EM) research community landscape prior to the initiation of a nationwide network. METHODS: A two-phase electronic survey was sent to 17 Canadian medical schools. The Phase 1 Environmental Scan was administered to department chairs/hospital EM chiefs, to identify EM physicians conducting clinical or educational research. The Phase 2 Survey was sent to the identified EM researchers to assess four themes: 1) geographic distribution, 2) training/career satisfaction, 3) time/financial compensation, and 4) research facilitators/barriers. Descriptive analyses were conducted, and results were stratified by Canadian regions. RESULTS: A total of 92 EM researchers were identified in Phase 1; 67 (73%) responded to the Phase 2 Survey. Of those, 42 (63%) reported being clinical researchers, and 19 (45%) had a graduate degree. Three provinces encompassed most of the researchers (n = 35). Of the respondents, 61% had a research degree, 66% felt adequately trained for their research career, 73% had financial support, 83% had access to office spaces, 52% had no mentor during their first years of their career, 69% felt satisfied with their research career, and 82% suggested that they will still be conducting research in 5 years. CONCLUSION: EM researchers reported being adequately trained, even though only a little over half had a graduate degree. Only two-thirds had financial support, and mentorship was lacking in one-third of the participants. Not all respondents had a form of infrastructure, but most felt optimistic about their careers. The Canadian EM research environment could be improved to ensure better research capacity.

Risk factors of significant pain syndrome 90 days after minor thoracic injury: trajectory analysis.

OBJECTIVES: The objective was to identify the risk factors of clinically significant pain at 90 days in patients with minor thoracic injury (MTI) discharged from the emergency department (ED). METHODS: A prospective, multicenter, cohort study was conducted in four Canadian EDs from November 2006 to November 2010. All consecutive patients aged 16 years or older with MTI were eligible at discharge from EDs. They underwent standardized clinical and radiologic evaluations at 1 and 2 weeks, followed by standardized telephone interviews at 30 and 90 days. A pain trajectory model characterized groups of patients with different pain evolutions and ascertained specific risk factors in each group through multivariate analysis. RESULTS: In this cohort of 1,132 patients, 734 were eligible for study inclusion. The authors identified a pain trajectory that characterized 18.2% of the study population experiencing clinically significant pain (>3 of 10) at 90 days after a MTI. Multivariate modeling found two or more rib fractures, smoking, and initial oxygen saturation below 95% to be predictors of this group of patients. CONCLUSIONS: To the authors' knowledge, this is the first prospective study of trajectory modeling to detect risk factors associated with significant pain at 90 days after MTI. These factors may help in planning specific treatment strategies and should be validated in another prospective cohort.

Adherence to calcium channel blocker poisoning treatment recommendations in two Canadian cities.

CONTEXT: No study has documented whether physicians call poison control centres (PCC) for calcium channel blocker (CCB) poisoning or if interventions suggested by the PCC are being applied. OBJECTIVES: This study evaluated the compliance of physicians with the Quebec Poison Control Center's (QPCC) recommendations for the treatment of CCB poisoning. It also assessed the outcomes of these patients. METHODS: This retrospective chart review was conducted with CCB-poisoned adults who were admitted to a hospital in Quebec City or Montreal between January 2004 and November 2007. Using the sequence of interventions, it was determined whether or not the PPC recommendations were adhered to. Level of care provided, morbidity and mortality were reported. The researchers also used the QPCC database to verify if the poison centre was consulted for the care of the patient. RESULTS: A total of 103 cases were identified. 42% (43/103) were classified as compliant (all PCC recommendations were followed) and 58% (60/103) non-compliant group (some or no PCC recommendations followed). The poison control centre (PCC) was contacted for 74% of the total cases (81% of cases in the compliant group and 68% in the non-compliant group). High-dose insulin euglycemia therapy (HIET) was not started when indicated or started at too low dosage in 20 cases. Glucagon was given, even if not indicated, in 14 cases and decontamination was inappropriate in at least 10 cases. For the entire sample, there was an average of 8 days of hospitalization, 47 h of intensive care, 11 h of vasopressor use, a morbidity of 50% and a mortality of 6%. Acute renal failure (35%), metabolic acidosis (25%), acute pulmonary oedema (15%), aspiration pneumonia (15%), rhabdomyolysis (8%), myocardial ischemia (7%), abnormal liver function tests (AST/ALT) (6%), cerebral anoxia (4%) and ileus (3%) were among the most frequent complications. The outcomes in the non-compliant group versus the compliant group showed a mortality of 10% versus 0% (95%CI 0.00-0.20, p-value < 0.0001), a morbidity 67% versus 26% (95%CI 0.17-0.57, p-value < 0.0001) (OR 0.21 unadjusted and 0.64 adjusted, p-value < 0.0001), a median hospital length of stay (LOS) of 5 days versus 1 da y (p-value < 0.0001) (OR of a LOS ≥ 1 day 0.23 unadjusted and 0.39 adjusted, p-value < 0.0001), a median ICU LOS of 34 h versus 0 h (p-value < 0.0001) (OR of a ICU LOS ≥ 1 day 0.16 unadjusted and 0.38 adjusted, p-value < 0.0001) and a median duration of vasopressor of 17 h versus 3 h (p-value 0.0002) (OR of a vasopressor ≥ 1 h 0.15 unadjusted and 0.29 adjusted, p-value < 0.0001). CONCLUSION: In conclusion, the majority of the physicians did not follow PCC recommendations for the treatment of CCB poisoning. Further studies are ongoing as to evaluate the barriers to protocol adherence and to develop evidence based guidelines accompanied by an effective implementation strategy.

Statistical validation of the Revised Trauma Score.

BACKGROUND: To validate the accuracy of the Revised Trauma Score (RTS) and its components for predicting in-hospital mortality. METHODS: Analyses were based on 22,388 patients from the trauma registries of three urban Level I trauma centers in the province of Quebec, Canada. The accuracy of RTS coded variables for the Glasgow Coma Score (GCSc), Systolic Blood Pressure (SBPc), and Respiratory Rate (RRc) for predicting mortality was evaluated in logistic regression models with measures of discrimination and model fit and compared with Fractional Polynomial (FP) transformations of each component. RESULTS: RTS coded variables were associated with sparse data distributions and did not accurately represent the relation of GCS, SBP, and RR to mortality. FP models were always associated with significantly better discrimination (all p < 0.00001) and model fit. Survival probability estimates generated by the model with FP transformations were significantly different to those generated by the model with RTS-coded variables. CONCLUSIONS: The RTS in its present form does not accurately describe the relation of GCS, SBP, and RR to mortality. FP transformation would improve the accuracy of predicted survival probabilities used for performance evaluation and may improve control of confounding caused by of physiologic severity case mix in trauma research.

The Injury Severity Score or the New Injury Severity Score for predicting intensive care unit admission and hospital length of stay?

OBJECTIVES: To compare the New Injury Severity Score (NISS) and the Injury Severity Score (ISS) as predictors of intensive care unit (ICU) admission and hospital length of stay (LOS) in an urban North American trauma population and in a subset of patients with head injuries. METHODS: The study population consisted of 23,909 patients from three urban level I trauma centres in the province of Quebec, Canada. The predictive accuracies of the NISS and the ISS were compared using Receiver Operator Characteristic (ROC) curves and Hosmer-Lemeshow (H-L) statistics for the logistic regression model of ICU admission and using r2 for the linear regression model of LOS. RESULTS: A total of 7660 (32%) patients were admitted to the ICU. Mean LOS was 8.2+/-2.5 days. In the whole sample, the NISS presented equivalent discrimination (area under ROC curve: NISS = 0.839 versus ISS = 0.843, p = 0.08) but better calibration (H-L statistic: 309 versus 611) for predicting ICU admission. In the subgroup patients with moderate to serious head injuries, the NISS was a better predictor of ICU admission in terms of both discrimination (area under ROC curve: NISS = 0.771 versus ISS = 0.747, p < 0.00001) and calibration (H-L statistic: 12 versus 21). The NISS explained more variation in LOS than the ISS for the whole sample (r2 = 0.254 versus 0.249, p = 0.0008) and in the sub-population with moderate to severe head injuries (r2 = 0.281 versus 0.263, p = 0.0002). CONCLUSIONS: The NISS is a better choice for case mix control in trauma research than the ISS for predicting ICU admission and LOS, particularly among patients with moderate to severe head injuries.

The New Injury Severity Score: a more accurate predictor of in-hospital mortality than the Injury Severity Score.

OBJECTIVE: The purpose of this study was to determine whether the New Injury Severity Score (NISS) is a better predictor of mortality than the Injury Severity Score (ISS) in general and in subgroups according to age, penetrating trauma, and body region injured. METHODS: The study population consisted of 24,263 patients from three urban Level I trauma centers in the province of Quebec, Canada. Discrimination and calibration of NISS and ISS models were compared using receiver operator characteristic (ROC) curves and Hosmer-Lemeshow statistics. RESULTS: NISS showed better discrimination than ISS (area under the ROC curve = 0.827 vs. 0.819; p = 0.0006) and improved calibration (Hosmer-Leme-show = 62 vs. 112). The advantage of the NISS over the ISS was particularly evident among patients with head/neck injuries (area under the ROC curve = 0.819 vs. 0.784; p < 0.0001; Hosmer-Lemeshow = 59 vs. 350). CONCLUSION: The NISS is a more accurate predictor of in-hospital death than the ISS and should be chosen over the ISS for case-mix control in trauma research, especially in certain subpopulations such as head/neck-injured patients.