Mind the gap: Can a professional development programme build a university’s public engagement community?

A number of ‘gaps’ may be present within public engagement with research – disparity of skills, priorities and knowledge between research staff and engagement practitioners, as well as differences between institutional ambition and departmental reality. Such gaps are often perceived as problems – deficits to be addressed through training and culture change initiatives. The design and delivery of Imperial College London’s Engagement Academy with 12 members of research, teaching and professional services staff sought to explore and work across such gaps. We propose that these areas of disconnect within and across universities may be challenging, but they may also be structurally necessary, and potentially even a source of rich public engagement

Rate coefficients for the reactions of OH with butanols from 298 K to temperatures relevant for low‐temperature combustion

Rate coefficients for the reactions of OH with n, s, and iso‐butanol have been measured over the temperature range 298 to ∼650 K. The rate coefficients display significant curvature over this temperature range and bridge the gap between previous low‐temperature measurements with a negative temperature dependence and higher temperature shock tube measurements that have a positive temperature dependence. In combination with literature data, the following parameterizations are recommended: k1,OH + n‐butanol(T) = (3.8 ± 10.4) × 10−19T2.48 ± 0.37exp ((840 ± 161)/T) cm3 molecule−1 s−1 k2,OH + s‐butanol(T) = (3.5 ± 3.0) × 10−20T2.76 ± 0.12exp ((1085 ± 55)/T) cm3 molecule−1 s−1 k3,OH + i‐butanol(T) = (5.1 ± 5.3) × 10−20T2.72 ± 0.14exp ((1059 ± 66)/T) cm3 molecule−1 s−1 k4,OH + t‐butanol(T) = (8.8 ± 10.4) × 10−22T3.24 ± 0.15exp ((711 ± 83)/T) cm3 molecule−1 s−1 Comparison of the current data with the higher shock tube measurements suggests that at temperatures of ∼1000 K, the OH yields, primarily from decomposition of β‐hydroxyperoxy radicals, are ∼0.3 (n‐butanol), ∼0.3 (s‐butanol) and ∼0.2 (iso‐butanol) with β‐hydroxyperoxy decompositions generating OH, and a butene as the main products. The data suggest that decomposition of β‐hydroxyperoxy radicals predominantly occurs via OH elimination

A new method for atmospheric detection of the CH3O2 radical

A new method for measurement of the methyl peroxy (CH3O2) radical has been developed using the conversion of CH3O2 into CH3O by excess NO with subsequent detection of CH3O by fluorescence assay by gas expansion (FAGE) with laser excitation at ca. 298 nm. The method can also directly detect CH3O, when no nitric oxide is added. Laboratory calibrations were performed to characterise the FAGE instrument sensitivity using the conventional radical source employed in OH calibration with conversion of a known concentration of OH into CH3O2 via reaction with CH4 in the presence of O2. Detection limits of 3.8 × 108 and 3.0 × 108 molecule cm−3 were determined for CH3O2 and CH3O respectively for a signal-to-noise ratio of 2 and 5 min averaging time. Averaging over 1 h reduces the detection limit for CH3O2 to 1.1 × 108 molecule cm−3, which is comparable to atmospheric concentrations. The kinetics of the second-order decay of CH3O2 via its self-reaction were observed in HIRAC (Highly Instrumented Reactor for Atmospheric Chemistry) at 295 K and 1 bar and used as an alternative method of calibration to obtain a calibration constant with overlapping error limits at the 1σ level with the result of the conventional method of calibration. The overall uncertainties of the two methods of calibrations are similar – 15 % for the kinetic method and 17 % for the conventional method – and are discussed in detail. The capability to quantitatively measure CH3O in chamber experiments is demonstrated via observation in HIRAC of CH3O formed as a product of the CH3O2 self-reaction

A new instrument for time-resolved measurement of HO2 radicals

OH and HO2 radicals are closely coupled in the atmospheric oxidation and combustion of volatile organic compounds (VOCs). Simultaneous measurement of HO2 yields and OH kinetics can provide the ability to assign site-specific rate coefficients that are important for understanding the oxidation mechanisms of VOCs. By coupling a fluorescence assay by gaseous expansion (FAGE) laser-induced fluorescence (LIF) detection system for OH and HO2 with a high-pressure laser flash photolysis system, it is possible to accurately measure OH pseudo-1st-order loss processes up to ∼100 000 s−1 and to determine HO2 yields via time-resolved measurements. This time resolution allows discrimination between primary HO2 from the target reaction and secondary production from side reactions. The apparatus was characterized by measuring yields from the reactions of OH with H2O2 (1:1 link between OH and HO2), with C2H4∕O2 (where secondary chemistry can generate HO2), with C2H6∕O2 (where there should be zero HO2 yield), and with CH3OH∕O2 (where there is a well-defined HO2 yield). As an application of the new instrument, the reaction of OH with n-butanol has been studied at 293 and 616 K. The bimolecular rate coefficient at 293 K, (9.24±0.21)×10−12 cm3 molec.−1 s−1, is in good agreement with recent literature, verifying that this instrument can measure accurate OH kinetics. At 616 K the regeneration of OH in the absence of O2, from the decomposition of the β-hydroxy radical, was observed, which allowed the determination of the fraction of OH reacting at the β site (0.23±0.04). Direct observation of the HO2 product in the presence of oxygen has allowed the assignment of the α-branching fractions (0.57±0.06) at 293 K and (0.54±0.04) at 616 K, again in good agreement with recent literature; branching ratios are key to modelling the ignition delay times of this potential “drop-in” biofuel

Kinetics of CH₂OO reactions with SO₂, NO₂, NO, H₂O and CH₃CHO as a function of pressure

Kinetics of CH₂OO Criegee intermediate reactions with SO₂, NO₂, NO, H₂O and CH₃CHO and CH₂I radical reactions with NO₂ are reported as a function of pressure at 295 K. Measurements were made under pseudo-first-order conditions using flash photolysis of CH₂I₂–O₂–N₂ gas mixtures in the presence of excess co-reagent combined with monitoring of HCHO reaction products by laser-induced fluorescence (LIF) spectroscopy and, for the reaction with SO₂, direct detection of CH₂OO by photoionisation mass spectrometry (PIMS). Rate coefficients for CH₂OO + SO₂ and CH₂OO + NO₂ are independent of pressure in the ranges studied and are (3.42 ± 0.42) × 10‾¹¹ cm³ s‾¹ (measured between 1.5 and 450 Torr) and (1.5 ± 0.5) × 10‾¹² cm³ s‾¹ (measured between 25 and 300 Torr), respectively. The rate coefficient for CH₂OO + CH₃CHO is pressure dependent, with the yield of HCHO decreasing with increasing pressure. Upper limits of 2 × 10−13 cm³ s‾¹ and 9 × 10−17 cm³ s‾¹ are placed on the rate coefficients for CH₂OO + NO and CH₂OO + H₂O, respectively. The upper limit for the rate coefficient for CH₂OO + H₂O is significantly lower than has been reported previously, with consequences for modelling of atmospheric impacts of CH₂OO chemistry

Equity in informal science learning: a practice-research brief

This briefi ng paper reports fi ndings from the Youth Access & Equity in Informal Science Learning (ISL) project, a UK-US researcher-practitioner partnership funded by the Science Learning+ scheme. Our project focuses on young people aged 11-14 primarily from under-served and non-dominant communities and includes researchers and practitioners from a range of ISL settings: designed spaces (eg museums, zoos), community-based (eg after school clubs) and everyday science spaces (eg science media)

An instrument to measure fast gas phase radical kinetics at hight temperatures and pressures

Fast radical reactions are central to the chemistry of planetary atmospheres and combustion systems. Laser-induced fluorescence is a highly sensitive and selective technique that can be used to monitor a number of radical species in kinetics experiments, but is typically limited to low pressure systems owing to quenching of fluorescent states at higher pressures. The design and characterisation of an instrument is reported using laser-induced fluorescence detection to monitor fast radical kinetics (up to 25,000 s-1) at high temperatures and pressures by sampling from a high pressure reaction region to a low pressure detection region. Kinetics have been characterised at temperatures reaching 740 K and pressures up to 2 atm, with expected maximum operational conditions of up to ~ 900 K and ~ 5 atm. The distance between the point of sampling from the high pressure region and the point of probing within the low pressure region is critical to the measurement of fast kinetics. The instrumentation described in this work can be applied to the measurement of kinetics relevant to atmospheric and combustion chemistry

Production of HO₂ and OH radicals from near-UV irradiated airborne TiO₂ nanoparticles

The production of gas-phase hydroperoxyl radicals, HO2, is observed directly from sub-micron airborne TiO2 nanoparticles (80% anatase and 20% rutile formulation) irradiated by 300 – 400 nm radiation. The rate of HO2 production as a function of O2 pressure follows Langmuir isotherm behaviour suggesting O2 is involved in the production of HO2 following its adsorption onto the surface of the TiO2 aerosol. Reduction of adsorbed O2 by photogenerated electrons is likely to be the initial step followed by reaction with a proton produced via oxidation of adsorbed water with a photogenerated hole. The rate of HO2 production decreased significantly over the range of relative humidities between 8.7 and 36.9 %, suggesting further adsorption of water vapour inhibits HO2 production. The adsorption equilibrium constants were calculated to be: KO2 = 0.27 ± 0.02 Pa-1 and KH2O = 2.16 ± 0.12 Pa-1 for RH = 8.7%, decreasing to KO2 = 0.18 ± 0.01 Pa-1 and KH2O = 1.33 ± 0.04 Pa-1 at RH = 22.1%. The increased coverage of H2O onto the TiO2 aerosol surface may inhibit HO2 production by decreasing the effective surface area of the TiO2 particle and lowering the binding energy of O2 on the aerosol surface, hence shortening its desorption lifetime. The yield of HO2 for atmospheric levels of O2 and normalised for surface area and light intensity was found to be k′prod = (3.64 ± 0.04) × 10-3 HO2 molecule photon-1 at RH = 8.7%. This yield decreased to k′prod = (1.97 ± 0.03) × 10-3 molecule photon-1 as the RH was increased to 22.1%. Using this value, the rate of production of HO2 from TiO2 surfaces under atmospheric conditions was estimated to be in the range 5x104 – 1x106 molecule cm-3 s-1 using observed surface areas of mineral dust at Cape Verde, and assuming a TiO2 fraction of 4.5%. For the largest loadings of dust in the troposphere, the rate of this novel heterogeneous production mechanism begins to approach that of HO2 production from the gas-phase reaction of OH with CO in unpolluted regions.The production of gas-phase OH radicals could only be observed conclusively at high aerosol surface areas, and was attributed to the decomposition of H2O2 at the surface by photogenerated electrons

Youth equity pathways in informal science learning

This infographic reports findings from the Youth Access & Equity in Informal Science Learning (ISL) project, a UK-US researcher-practitioner partnership funded by the Science Learning+ Phase 1 scheme. Our project focuses on young people aged 11-14 primarily from under-served and non-dominant communities and includes researchers and practitioners from a range of ISL settings: designed spaces (eg museums, zoos), community-based (eg afterschool clubs) and everyday science spaces (eg science media)