The role of composition on the ammonia synthesis activity of nitrides, carbonitrides, carbides and osmium based compounds

The industrial route for producing ammonia is via the Haber-Bosch Process and requires high temperatures and pressures. When considered in its entirety, including the production of the necessary feedstreams, the process is stated to account for 2% of the world’s energy demand and 1.6% of global anthropogenic CO2 emissions. If a more active ammonia synthesis catalyst was developed, it may prove possible to operate under more moderate conditions, facilitating localised and sustainable production. One potential approach to the development of catalysts with enhanced activity by-passing the limiting scaling relationship invoked for metal catalysts is ammonia production via the Mars-van Krevelen mechanism, as possibly exhibited by some metal nitrides, such as Co3Mo3N. The role composition and crystal structure type have on the ammonia synthesis activity of mixed metal nitrides, carbonitrides and carbides was investigated within this thesis. Fe3Mo3C, Ni6Mo6C, Ni3Mo3C and Ni2Mo3CxNy have been tested for their ammonia synthesis capabilities, to discover if the presence of lattice nitrogen was required. Fe3Mo3C was found to be inactive for ammonia synthesis at 400oC. However, when the temperature was increased to 500oC, the material became active, which may be related to the substitution of lattice carbon with nitrogen. Ni6Mo6C and Ni3Mo3C were inactive for ammonia synthesis at 400oC and 500oC, respectively. When Ni6Mo6C and Ni3Mo3C were investigated at 700oC, an induction period occurred before the two materials developed activity for ammonia synthesis; during this period, nitridation of the lattice occurred eventually leading to the formation of Ni2Mo3N. Ni2Mo3C could not be synthesised via a topotactic route from Ni2Mo3N and the carbonitride phase which was formed was active for ammonia synthesis at 400oC. The lattice nitrogen in the filled b-Mn structured Ni2Mo3N and h-carbide structured Ni2GaMo3N was observed to exhibit different behaviour to that in the filled b-Mn structured Co2Mo3N and h-carbide structured Co3Mo3N and Fe3Mo3N. For Ni2Mo3N and Ni2GaMo3N, the bulk lattice nitrogen appeared to be relatively unreactive at 900oC, whereas Co2Mo3N, Co3Mo3N and Fe3Mo3N decomposed under these conditions. This suggests that both composition and crystal structure type may have an impact on the lattice nitrogen reactivity. The potential structure sensitivity of osmium for ammonia synthesis was examined and it was found that the metal was more active when it was more highly dispersed. Supported mixed metal carbonyl clusters were also tested and were observed to have different activities to the supported monometallic equivalents

The Effects of Passive Avoidance Learning on the Release of Amino Acids and other Putative Transmitters in the Forebrain of the Day-old Chick.

The time course of release of amino add transmitters was examined in slices of IMHV and LPO from day-old chicks that had completed a one-trial passive avoidance learning task. Amino adds released into an incubation medium were measured using FITC-derivatisation followed by an adaptation of a published method for HPLC analysis. One hour after training chicks to avoid a bead covered with the a versant methylanthranilate (MeA), there was an increase in the Ca2+-dependent release of glutamate, aspartate and GABA from slices of left IMHV compared to chicks trained to peck a similar bead covered in water. Thirty minutes after training glutamate only was increased in MeA-chicks, but from both IMHVs. Glutamate was also increased at 3 and 6.5 hours in the right IMHV as was GABA (6.5 hours) and aspartate (3 hours). Both left and right LPOs of MeA-trained chicks showed increased GABA and glutamate release ac 3, 6.5 and 24 hours. The left only showed enhanced release of both at 30 minutes. The release of the neuromodulator adenosine was found to be increased in the IMHV of MeA-trained chicks simultaneous to the increases in glutamate. The adenosine agonist CHA inhibited glutamate release: its actions blocked by the antagonist CPT. An agonist for the excitatory adenosine receptor increased glutamate, but decreased GABA, release according to concentration applied. Pre-training injections of adenosine agonists produced amnesia 30 minutes after training: these effects were lateralised such that injections into the left hemisphere only produced amnesia, those into the right did not. These results demonstrate for the first time increases in amino acid transmitters associated with passive avoidance training, and suggest a role for adenosine modulation of these transmitters

Language and ideology in West, Macaulay, and Woolf

At the outbreak of the First World War, the archaic principles of nationalism and masculinity ruled Britain. These principles placed on men expectations that had become unrealistic due to the changed nature of warfare. The new horrors of war and the loss of the masculine characteristic of self-control produced a high frequency of combat trauma. For such victims of the war, the healing of psychological conditions required the assignment of meaning to their trauma, accomplished through the communication of loss to the civilian population. The problem was the inability of most non-combatants, including medical doctors, to comprehend ideas outside of the language-supported ideology that governed perception of reality. Instead of empathy, traumatized veterans were met with demands of conformity to the standards of masculinity established long before the war. Veterans who dissented from the official line of God, King and Country were silenced by the very society they fought to protect. Women writers, however, were free from the strictures of masculinity and were thus able to act as proxies to their counterparts. Rebecca West, Rose Macaulay, and Virginia Woolf challenged the dominant assumptions of war trauma and masculinity, each identifying language and anachronous ideology as the primary means used to promote conventional thought and silence discordance in society

COVID-19: a closer look at the pathology in two autopsied cases. Is the pericyte at the center of the pathological process in COVID-19?

We performed autopsies on two cases of COVID-19. The microcirculations of all organs were the site of the pathological findings. Thrombotic microangiopathy was found in the brain and also the kidneys. Vasculitis was also a feature of the autopsy findings, together with portal triaditis of the liver. The major pathological findings in both cases were fibrin deposits. Within the lung, the fibrin deposits were observed in the alveolar microcirculation in sub-endothelial locations of capillaries, arterioles, post capillary venules, and the adventitia of larger vessels. These fibrin deposits in the lungs occurred at the sites where pericytes are located in these vessels. The pericyte with its high concentration of ACE-2 receptors and its procoagulant state may represent one of the primary sites of action of SARS-CoV-2. A review of pericytes in health and disease is undertaken. COVID-19 is a disease of the microcirculation

Towards anti-perovskite nitrides as potential nitrogen storage materials for chemical looping ammonia production: reduction of Co₃ZnN, Ni₃ZnN, Co₃InN, Ni₃InN under hydrogen

The ammonia production properties upon reduction in hydrogen of the anti-perovskite nitrides Co₃ZnN, Ni₃ZnN, Co₃InN, and Ni₃InN have been investigated. Single phases with ideal anti-perovskite structures (Space group: Pm-3m) were prepared for all the nitrides by the ammonolysis of the corresponding precursor oxides and all the nitrides were observed to produce ammonia in high yields when reacted with H2/Ar. The cumulative ammonia production values at 400 °C were 3069, 2925, 289, and 1029 μmol-NH3 g⁻¹ for Co₃ZnN, Ni₃ZnN, Co₃InN, and Ni₃InN, respectively and the order of the release rates was Ni₃ZnN > Co₃ZnN > Ni₃InN > Co₃InN. X-ray diffraction studies revealed that Co₃ZnN and Co₃InN were decomposed upon the loss of lattice N, whereas Ni₃ZnN and Ni₃InN were transformed into Ni₃Zn and Ni₃In via the intermediate phases Ni₃ZnNₓ and Ni₃InNᵧ. The crystal structures of these intermediate phases are related to their initial structures, indicating that the loss of lattice N in Ni₃ZnN and Ni3InN was topotactic

Calcitriol in the Management of Secondary Hyperparathyroidism of Renal Failure

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90092/1/j.1875-9114.1996.tb03644.x.pd

A comparison of the activities of various supported catalysts for ammonia synthesis

The present study presents an empirical screening study of the catalytic performance of a variety of supported materials for ammonia synthesis at 400 and 500 °C. Amongst the materials tested, those derived from Ru/Al2O3 exhibited the best performance. Supported Os and CoRe catalysts also demonstrated comparatively high activities indicating them to be potentially worthy of further investigation

Metal nitrides, the Mars-van Krevelen mechanism and heterogeneously catalysed ammonia Synthesis

Whilst the Mars-van Krevelen mechanism is well established for metal oxide catalysed oxidation reactions, it has been much less studied in the case of nitrogen based reactions catalysed by metal nitrides. In this overview, some of the recent literature in relation to the possible operation of the Mars- van Krevelen mechanism for ammonia synthesis catalysed by metal nitrides is presented, along with some of the literature relating to the synthesis of ammonia via chemical looping approaches

Deleterious Effects of Neonicotinoid Pesticides on Drosophila melanogaster Immune Pathways

Copyright © 2019 Chmiel et al. Neonicotinoid insecticides are common agrochemicals that are used to kill pest insects and improve crop yield. However, sublethal exposure can exert unintentional toxicity to honey bees and other beneficial pollinators by dysregulating innate immunity. Generation of hydrogen peroxide (H2O2) by the dual oxidase (Duox) pathway is a critical component of the innate immune response, which functions to impede infection and maintain homeostatic regulation of the gut microbiota. Despite the importance of this pathway in gut immunity, the consequences of neonicotinoid exposure on Duox signaling have yet to be studied. Here, we use a Drosophila melanogaster model to investigate the hypothesis that imidacloprid (a common neonicotinoid) can affect the Duox pathway. The results demonstrated that exposure to sublethal imidacloprid reduced H2O2 production by inhibiting transcription of the Duox gene. Furthermore, the reduction in Duox expression was found to be a result of imidacloprid interacting with the midgut portion of the immune deficiency pathway. This impairment led to a loss of microbial regulation, as exemplified by a compositional shift and increased total abundance of Lactobacillus and Acetobacter spp. (dominant microbiota members) found in the gut. In addition, we demonstrated that certain probiotic lactobacilli could ameliorate Duox pathway impairment caused by imidacloprid, but this effect was not directly dependent on the Duox pathway itself. This study is the first to demonstrate the deleterious effects that neonicotinoids can have on Duox-mediated generation of H2O2 and highlights a novel coordination between two important innate immune pathways present in insects.IMPORTANCE Sublethal exposure to certain pesticides (e.g., neonicotinoid insecticides) is suspected to contribute to honey bee (Apis mellifera) population decline in North America. Neonicotinoids are known to interfere with immune pathways in the gut of insects, but the underlying mechanisms remain elusive. We used a Drosophila melanogaster model to understand how imidacloprid (a common neonicotinoid) interferes with two innate immune pathways-Duox and Imd. We found that imidacloprid dysregulates these pathways to reduce hydrogen peroxide production, ultimately leading to a dysbiotic shift in the gut microbiota. Intriguingly, we found that presupplementation with probiotic bacteria could mitigate the harmful effects of imidacloprid. Thus, these observations uncover a novel mechanism of pesticide-induced immunosuppression that exploits the interconnectedness of two important insect immune pathways