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•Interest of experimentalists in a low pressure ammonia synthesis process.•The electro-catalytic ammonia rates are still far from scale-up requirements.•DFT studies point to ...transition metal nitrides as promising electro-catalysts
Ammonia is one of the most important and widely produced chemicals worldwide with a key role in the growth of human population. Nowadays, the main route for ammonia synthesis is the Haber-Bosch process, developed a century ago. In this process, Fe-based catalysts are usually employed at temperatures between 400 and 500°C and pressures between 130 and 170bar. As opposed to the industrial process, in nature, plants and bacteria have been producing ammonia for millions of years at mild conditions. Atmospheric nitrogen is reduced by solvated protons on the FeMo cofactor of the metalloenzyme nitrogenase. The natural method of nitrogen fixation has motivated several research groups to explore the electrochemical synthesis of ammonia at ambient pressure. Since it was first demonstrated in 1998, the electrochemical synthesis has been studied in a variety of experimental configurations over a wide temperature range (25–800°C). In the present review, the progress of this method in both solid and liquid electrolyte cells is reported. The experimental studies are divided into high (T>500°C), intermediate (500°C>T>100°C) and low (T<100°C) temperatures. The experimental observations are comparatively discussed with theoretical predictions based on DFT calculations. The techno-economic advantages and disadvantages of the electrochemical approach, as well as the requirements to be met in order to enable practical applications are also analyzed.
Reports of ChAdOx1 vaccine-associated thrombocytopenia and vascular adverse events have led to some countries restricting its use. Using a national prospective cohort, we estimated associations ...between exposure to first-dose ChAdOx1 or BNT162b2 vaccination and hematological and vascular adverse events using a nested incident-matched case-control study and a confirmatory self-controlled case series (SCCS) analysis. An association was found between ChAdOx1 vaccination and idiopathic thrombocytopenic purpura (ITP) (0-27 d after vaccination; adjusted rate ratio (aRR) = 5.77, 95% confidence interval (CI), 2.41-13.83), with an estimated incidence of 1.13 (0.62-1.63) cases per 100,000 doses. An SCCS analysis confirmed that this was unlikely due to bias (RR = 1.98 (1.29-3.02)). There was also an increased risk for arterial thromboembolic events (aRR = 1.22, 1.12-1.34) 0-27 d after vaccination, with an SCCS RR of 0.97 (0.93-1.02). For hemorrhagic events 0-27 d after vaccination, the aRR was 1.48 (1.12-1.96), with an SCCS RR of 0.95 (0.82-1.11). A first dose of ChAdOx1 was found to be associated with small increased risks of ITP, with suggestive evidence of an increased risk of arterial thromboembolic and hemorrhagic events. The attenuation of effect found in the SCCS analysis means that there is the potential for overestimation of the reported results, which might indicate the presence of some residual confounding or confounding by indication. Public health authorities should inform their jurisdictions of these relatively small increased risks associated with ChAdOx1. No positive associations were seen between BNT162b2 and thrombocytopenic, thromboembolic and hemorrhagic events.
Severe Acute Respiratory Syndrome coronavirus-2 (SARS-CoV-2) has challenged public health agencies globally. In order to effectively target government responses, it is critical to identify the ...individuals most at risk of coronavirus disease-19 (COVID-19), developing severe clinical signs, and mortality. We undertook a systematic review of the literature to present the current status of scientific knowledge in these areas and describe the need for unified global approaches, moving forwards, as well as lessons learnt for future pandemics.
Medline, Embase and Global Health were searched to the end of April 2020, as well as the Web of Science. Search terms were specific to the SARS-CoV-2 virus and COVID-19. Comparative studies of risk factors from any setting, population group and in any language were included. Titles, abstracts and full texts were screened by two reviewers and extracted in duplicate into a standardised form. Data were extracted on risk factors for COVID-19 disease, severe disease, or death and were narratively and descriptively synthesised.
One thousand two hundred and thirty-eight papers were identified post-deduplication. Thirty-three met our inclusion criteria, of which 26 were from China. Six assessed the risk of contracting the disease, 20 the risk of having severe disease and ten the risk of dying. Age, gender and co-morbidities were commonly assessed as risk factors. The weight of evidence showed increasing age to be associated with severe disease and mortality, and general comorbidities with mortality. Only seven studies presented multivariable analyses and power was generally limited. A wide range of definitions were used for disease severity.
The volume of literature generated in the short time since the appearance of SARS-CoV-2 has been considerable. Many studies have sought to document the risk factors for COVID-19 disease, disease severity and mortality; age was the only risk factor based on robust studies and with a consistent body of evidence. Mechanistic studies are required to understand why age is such an important risk factor. At the start of pandemics, large, standardised, studies that use multivariable analyses are urgently needed so that the populations most at risk can be rapidly protected.
This review was registered on PROSPERO as CRD42020177714 .
In addition to their basic applications, i.e. sensors, separators, fuel cells and hydrogen pumps, high temperature proton conductors have also been used in the construction of proton conducting ...chemical reactors in which catalytic hydro- and dehydrogenations are studied. The fundamental operating principles and research works in the past decade are presented and evaluated. Recent results indicate that the most promising candidate systems for promotion to an industrial scale, are a) the conversion of methane to benzene, b) the C2H6 to C2H4 fuel cell, c) the H2S fuel cell and d) NH3 synthesis.
•Interest of researchers in high temperature proton conducting reactors•The conversion of methane to benzene•The C2H6 to C2H4 fuel cell; the H2S fuel cell•Electrochemical ammonia synthesis
The electrochemical synthesis of ammonia from N2 and H+ ions was studied over a Ni–BZCY72 cermet, with and without H2 in the gas phase. The effect of temperature, cathode chamber feed composition and ...applied voltage was explored in detail. Without H2 in the cathode chamber, the highest rate was 1.7×10−9mol/s·cm2 at 620°C. When H2 was present in the gas phase, ammonia was synthesized electrochemically at much higher rates and Faradaic efficiencies. The maximum net electrochemical synthesis rate of 4.1×10−9mol/s·cm2 was obtained with ΡΗ2/ΡΝ2=1 at 620°C, corresponding to a 140% enhancement of the open circuit rate at the cost of electrical energy. In both cases these high rates were accompanied by a low Faradaic efficiency, pointing to the need for catalyst improvement.
•Electrochemical synthesis of ammonia is enhanced by co-feeding H2 to the cathode.•A high open circuit rate can be electrochemically enhanced by up to 140%.•Electrochemical synthesis is optimal at equimolar and not at stoichiometric feed.•High current densities can have a negative effect on electrochemical synthesis.
Managed Aquifer Recharge is a wide-spread well-established groundwater engineering method which is largely seen as sound and sustainable solution to water scarcity hydrologically sensitive areas, ...such as the Circum Mediterranean. The process of site selection for the installation of a MAR facility is of paramount importance for the feasibility and effectiveness of the project itself, especially when the facility will include the use of waters of impaired quality as a recharge source, as in the case of Soil-Aquifer-Treatment systems.
The main objective of this study is to present the developed framework of a multi-criteria Decision Support System (DSS) that integrates within a dynamic platform the main groundwater engineering parameters associated with MAR applications together with the general geographical features which determine the effectiveness of such a project. The proposed system will provide an advanced coupled DSS-GIS tool capable of handling local MAR-related issues -such as hydrogeology, topography, soil, climate etc., and spatially distributed variables -such as societal, economic, administrative, legislative etc., with special reference to Soil-Aquifer-Treatment technologies.
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•Optimal selection for Soil Aquifer Treatment systems is a fundamental step for sound wastewater reuse•Development of a Decision Support System coupled with GIS for site selection criteria for SAT facilities•Critical constraints and limitations are considered based on site specific criteria as well as on technical guidelines
The catalytic and electrocatalytic synthesis of ammonia was studied in a proton conducting double-chamber solid electrolyte cell. The BaZr
0.7
Ce
0.2
Y
0.1
O
2.9
(BZCY72) proton conducting ceramic ...was used as the electrolyte with a Ni-BZCY72 cermet and a Pt film serving as cathodic and anodic electrodes, respectively. The reaction was studied at atmospheric pressure and at temperatures between 450 and 700 °C, under both, open- and closed-circuit conditions. A peculiar reaction rate enhancement was observed when the cell returned to open-circuit after operating under closed-circuit for a certain time. A possible explanation of this new phenomenon is that a fraction of protons electrochemically transported to the cathode, is “stored” in the Ni-BZCY72 electrode in the form of a highly reactive hydride which, upon current interruption, reacts with adsorbed N species to produce ammonia.
At the end of 2020, many countries commenced a vaccination programme against SARS-CoV-2. Public health authorities aim to prevent and interrupt outbreaks of infectious disease in social care ...settings. We aimed to investigate the association between the introduction of the vaccination programme and the frequency and duration of COVID-19 outbreaks in Northern Ireland (NI).
We undertook an ecological study using routinely available national data.
We used Poisson regression to measure the relationship between the number of RT-PCR confirmed COVID-19 outbreaks in care homes, and as a measure of community COVID-19 prevalence, the Office for National Statistics COVID-19 Infection Survey estimated the number of people testing positive for COVID-19 in NI. We estimated the change in this relationship and estimated the expected number of care home outbreaks in the absence of the vaccination programme. A Cox proportional hazards model estimated the hazard ratio of a confirmed COVID-19 care home outbreak closure.
Care home outbreaks reduced by two-thirds compared to expected following the introduction of the vaccination programme, from a projected 1625 COVID-19 outbreaks (95% prediction interval 1553–1694) between 7 December 2020 and 28 October 2021 to an observed 501. We estimated an adjusted hazard ratio of 2.53 of the outbreak closure assuming a 21-day lag for immunity.
These findings describe the association of the vaccination with a reduction in outbreak frequency and duration across NI care homes. This indicates probable reduced harm and disruption from COVID-19 in social care settings following vaccination. Future research using individual level data from care home residents will be needed to investigate the effectiveness of the vaccines and the duration of their effects.
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