A combined periodic DFT and QM/MM approach to understand the radical mechanism of the catalytic production of methanol from glycerol.

The production of methanol from glycerol over a basic oxide, such as MgO, using high reaction temperatures (320 °C) is a promising new approach to improving atom efficiency in the production of biofuels. The mechanism of this reaction involves the homolytic cleavage of the C3 feedstock, or its dehydration product hydroxyacetone, to produce a hydroxymethyl radical species which can then abstract an H atom from other species. Obtaining a detailed reaction mechanism for this type of chemistry is difficult due to the large number of products present when the system is operated at high conversions. In this contribution we show how DFT based modelling studies can provide new insights into likely reaction pathways, in particular the source of H atoms for the final step of converting hydroxymethyl radicals to methanol. We show that water is unlikely to be important in this stage of the process, C-H bonds of C2 and C3 species can give an energetically favourable pathway and that the disproportionation of hydroxymethyl radicals to methanol and formaldehyde produces a very favourable route. Experimental analysis of reaction products confirms the presence of formaldehyde. The calculations presented in this work also provide new insight into the role of the catalyst surface in the reaction showing that the base sites of the MgO(100) are able to deprotonate hydroxymethyl radicals but not methanol itself. In carrying out the calculations we also show how periodic DFT and QM/MM approaches can be used together to obtain a rounded picture of molecular adsorption to surfaces and homolytic bond cleavage which are both central to the reactions studied.

Performance evaluation of a non-invasive one-step multiplex RT-qPCR assay for detection of SARS-CoV-2 direct from saliva.

Polymerase chain reaction (PCR) has proven to be the gold-standard for SARS-CoV-2 detection in clinical settings. The most common approaches rely on nasopharyngeal specimens obtained from swabs, followed by RNA extraction, reverse transcription and quantitative PCR. Although swab-based PCR is sensitive, swabbing is invasive and unpleasant to administer, reducing patient compliance for regular testing and resulting in an increased risk of improper sampling. To overcome these obstacles, we developed a non-invasive one-step RT-qPCR assay performed directly on saliva specimens. The University of Nottingham Asymptomatic Testing Service protocol simplifies sample collection and bypasses the need for RNA extraction, or additives, thus helping to encourage more regular testing and reducing processing time and costs. We have evaluated the assay against the performance criteria specified by the UK regulatory bodies and attained accreditation (BS EN ISO/IEC 17,025:2017) for SARS-CoV-2 diagnostic testing by the United Kingdom Accreditation Service. We observed a sensitivity of 1 viral copy per microlitre of saliva, and demonstrated a concordance of > 99.4% between our results and those of other accredited testing facilities. We concluded that saliva is a stable medium that allows for a highly precise, repeatable, and robust testing method.

Direct RT-qPCR Assay for the Detection of SARS-CoV-2 in Saliva Samples.

Since mid-2020 there have been complexities and difficulties in the standardisation and administration of nasopharyngeal swabs. Coupled with the variable and/or poor accuracy of lateral flow devices, this has led to increased societal 'testing fatigue' and reduced confidence in test results. Consequently, asymptomatic individuals have developed reluctance towards repeat testing, which remains the best way to monitor COVID-19 cases in the wider population. On the other hand, saliva-based PCR, a non-invasive, highly sensitive, and accurate test suitable for everyone, is gaining momentum as a straightforward and reliable means of detecting SARS-CoV-2 in symptomatic and asymptomatic individuals. Here, we provide an itemised list of the equipment and reagents involved in the process of sample submission, inactivation and analysis, as well as a detailed description of how each of these steps is performed.

Recent initiatives in experimental thermodynamic studies on ionic liquids [IL]--the emergence of a standard thermochemical database for ILs.

One of the ultimate goals in the exciting on-going development and study of ionic liquids (ILs) must be the quest to establish "before synthesis" tools that could be used to predict and guide synthetic chemists towards ILs having "tuned" target properties. The tools needed in this exercise will come from many sources, not least from the acquisition of standard experimental thermodynamic data. The routine measurement of such data for new compounds had become very much a thing of the past in traditional chemistry. However with the surge of interest across the globe seen in these relatively new IL materials has come a recognition of the need to acquire experimental data and this review article seeks to assemble much of the emerging thermochemical data for ILs in one place. After all, there are very few data in current existing thermochemical databases that could offer much of a clue concerning the specific thermodynamic behaviour of ILs. We are charting new territory here. Development of any new large scale commercial process is preceded these days by a full study of its thermodynamic feasibility, usually at the pilot stage, and thus such data as are reported here are of the utmost value in this respect. It has a secondary role too in enabling predictions of missing data to become feasible and hence in predicting synthetic outcomes ahead of practical experiment. This commentary tracks very recent trends and developments on the more quantitative and thermodynamic aspects of this exciting chemistry.

Ionic liquids--an overview.

A virtually unprecedented exponential burst of activity resulted following the publication, in 1998, of an article by Michael Freeman (Freemantle, M. Chemical & Engineering News, 1998, March 30, 32), which speculated on the role and contribution that ionic liquids (ILs) might make in the future on the development of clean technology. Up until that time only a handful of researchers were routinely engaged in the study of ILs but frenzied activity followed that continues until the present day. Scientists from all disciplines related to Chemistry have now embarked on studies, including theoreticians who are immersed in the aim of improving the "designer role" so that they can tailor ILs to deliver specified properties. This article, whilst not in any sense attempting to be exhaustive, highlights the main features which characterise ILs, presenting these in a form readily assimilated by newcomers to this area of research. An extensive glossary is featured in this article as well as a chronological list which charts the major areas of development. What follows consists of a number of sections briefly describing the role of lLs as solvents, hypergolic fuels, their use in some electrochemical devices such as solar cells and lithium batteries and their use in polymerisation reactions, followed by a concise summary of some of the other roles that they are capable of playing. The role of empirical, volume-based thermodynamics procedures, as well as large scale computational studies on ILs is also highlighted. These developments which are described are remarkable in that they have been achieved in less than a decade and a half although knowledge of these materials has existed for much longer.

Inorganic energetics from mainframe to "back-of-envelope".

On Thursday, 16 April 2009, Professor H. Donald. B. Jenkins presented an Exaugumral Lecture to a packed audience at the University of Warwiclk at a Symposium held to honour his retirement and to celebrate his 44-year career. This is a transcript of that lecture, which describes the evolution of a new approach to thermodynamics: volume-based thermodynamics (VBT) which is gaining in popularity and which is relatively simple to use. Reported also are a number of other simple relationships, capable of estimation of standard thermodynamic data, currently under development. Some of these are immensely powerful and they are described.

Crystalline thin films of silica: modelling, structure and energetics.

The static structural and energetic properties of thin crystalline films (∼two dimensional bilayers) of silica, SiO2, are modelled. Two potential models are considered in which the key interactions are described by purely harmonic terms and more complex electrostatic terms, respectively. The relative energetic stability of two potential crystalline forms, which represent alternative ways of tiling two dimensional space, is discussed. Coherent and incoherent distortions are introduced to the simulated crystals and their effects considered in terms of the ring structure formed by the Si atoms. The spatial relationship between distorted rings is analysed. An experimentally-observed single crystalline configuration is considered for comparison throughout.