We describe the method of history matching, a method currently used to help quantify parametric uncertainty in climate models, and argue for its use in identifying and removing structural biases in climate models at the model development stage. We illustrate the method using an investigation of the potential to improve upon known ocean circulation biases in a coupled non-flux-adjusted climate model (the third Hadley Centre Climate Model; HadCM3). In particular, we use history matching to investigate whether or not the behaviour of the Antarctic Circumpolar Current (ACC), which is known to be too strong in HadCM3, represents a structural bias that could be corrected using the model parameters. We find that it is possible to improve the ACC strength using the parameters and observe that doing this leads to more realistic representations of the sub-polar and sub-tropical gyres, sea surface salinities (both globally and in the North Atlantic), sea surface temperatures in the sinking regions in the North Atlantic and in the Southern Ocean, North Atlantic Deep Water flows, global precipitation, wind fields and sea level pressure. We then use history matching to locate a region of parameter space predicted not to contain structural biases for ACC and SSTs that is around 1% of the original parameter space. We explore qualitative features of this space and show that certain key ocean and atmosphere parameters must be tuned carefully together in order to locate climates that satisfy our chosen metrics. Our study shows that attempts to tune climate model parameters that vary only a handful of parameters relevant to a given process at a time will not be as successful or as efficient as history matching.
The oxidative cleavage of olefins is an integral process that converts feedstocks into highvalue synthetic intermediates 1,2,3 . The most viable method to oxidatively cleave C-Cπ bonds in one chemical step is with ozone 4,5,6,7 , which however poses technical and safety challenges owing to the explosive nature of ozonolysis products 8,9 . Herein, we present a distinct approach to achieve oxidative cleavage of olefins using nitroarenes and purple light irradiation. We demonstrate that photoexcited nitroarenes are effective ozone surrogates that undergo facile radical [3+2] cycloaddition with olefins. The resulting "Ndoped" ozonide cycloadducts are safe to handle and lead to the corresponding carbonyl products under mild hydrolytic conditions. These features have enabled the controlled cleavage of all types of olefins in the presence of a broad array of commonly used organic functionalities. Furthermore, by harnessing electronic, steric, and mediated polar effects, the structural and functional diversity of nitroarenes has provided a modular platform to obtain site-selectivity in substrates containing more than one olefin.Olefins are feedstock materials harvested on ton-scale from petroleum and vegetable biomass routinely exploited by the bulk chemical industry to access oxygen-enriched synthetic intermediates 1,2,3 . Ozonolysis is a widely adopted method to achieve this and requires a specialised apparatus for the conversion of molecular oxygen (O2) into highly reactive ozone (O3) 6,7 . This species undergoes a [1,3] dipolar cycloaddition with the olefin converting a stable chemical into a high-energy 1,2,3-ozonide A from which cycloreversion is immediate. The consequent C-C σ-bond cleavage event generates carbonyl oxide B and carbonyl compound C which recombine to give 1,2,4-ozonide D. Depending on reaction solvent and work-up procedure, B or D can lead to aldehydes/ketones as well as carboxylic acids or alcohols 4,5 (Fig. 1a).Despite its attractive synthetic versatility, ozone toxicity (lethal at 5 ppm), explosivity, and extreme oxidising power (E0 = 2.07 V) raise critical safety, technical, and chemical concerns 8,9 .As a result, ozonolytic strategies are often challenging to translate into the fine chemical industry 10,11,12 , particularly in the discovery sector which heavily relies on parallel and highthroughput screening platforms 13 . Consequently, alternative strategies for olefin oxidation based on high-valent heavy-metal oxides have been devised. However, these approaches can yield mixtures of products of various oxidation degrees, and cause trace metal contaminations
Vicinal diamines are ubiquitous materials in organic and medicinal chemistry. The direct coupling of olefins and amines would be an ideal approach to construct these motifs. However, alkene diamination remains a long‐standing challenge in organic synthesis, especially when using two different amine components. We report a general strategy for the direct and selective assembly of vicinal 1,2‐diamines using readily available olefin and amine building blocks. This mild and straightforward approach involves in situ formation and photoinduced activation of N‐chloroamines to give aminium radicals that enable efficient alkene aminochlorination. Owing to the ambiphilic nature of the β‐chloroamines produced, conversion into tetra‐alkyl aziridinium ions was possible, thus enabling diamination by regioselective ring‐opening with primary or secondary amines. This strategy streamlines the preparation of vicinal diamines from multistep sequences to a single chemical transformation.
In rats, like many rodents, Harderian glands next to the orbits secrete porphyrins, lipids and other compounds. High levels of secretion lead to chromodacryorrhoea (red or “bloody” tears), often taken as a sign of stress or disease. Here, we developed a scoring system for recording chromodacryorrhoea in a quantitative way, and investigated whether the low-level, transient Harderian secretions of normal, healthy rats correlate with low to moderate levels of stress or disturbance. Rather than exposing our subjects (24 Lister Hoodeds, housed in 11 single-sex cages) experimentally to stressors, we made opportunistic use of three likely sources of low-level stress within the unit: 1) building maintenance work, taking several hours and involving several potential stressors; 2) visits by unfamiliar humans, and the other mild sources of disturbance normal in an animal unit; and 3) social status within the cage. The mean daily chromodacryorrhoea score increased most with the severe disturbance of building maintenance work (F1,9 = 602.67, p << 0.0001), and also increased — though to a lesser extent — with the mild disturbance of visitors and similar (F1,9 = 8.77, p = 0.008), while being the subordinate member of a cage-group had a smaller effect still (F1,6 = 7.86, p = 0.03). Individual rats scored consistently across treatment conditions, and there was also significant inter-observer reliability between independent scorers. We therefore suggest that scoring chromodacryorrhoea could be a simple, practical and non-invasive way of sensitively assessing the impact on rats of housing, husbandry, or procedures.
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