The manufacture of a prototype laser machined chromatographic separations column

This thesis details the experimentation and developments in the production of a novel laser machined prototype graphitic separations column utilizing an array of graphitic micro-pillars. The column was created with a 5kHz Thales femtosecond laser, a highly focussed beam from a stationary multi-element focussing lens to machine the fluidic tracks and micro-pillared array directly into a graphitic block as a single structure. This novel HPLC column format could potentially create a much more robust separations column with respect to temperature and pressure and reduce the band broadening associated with conventional chromatographic columns because of the inhomogeneous bead packing and the influence of side walls. The computer-aided design (CAD) was developed in Alpha-Cam and converted into code for the motion control system in order to traverse the workpiece in X and Y with an Alpha-Cam post processor. An integrated on-chip sample injector and fluidic flow-distributor are incorporated onto the column to minimize band broadening and enable more equal fluid flow across it. Half pillars were machined into the edge of the array to minimize band broadening. The separation column was integrated directly with the ESI probe of a Thermo Fisher Surveyor mass spectrometer. The device was tested at HPLC pressures and successfully performed without leakage. It’s evaluation as a chromatographic separations column showed the repeated partial separation of two molecules. This represents the first demonstration of a micro-machined graphitic microfluidic device and it’s performance in separation science

"Wear your mask"

The current pandemic has made the wearing of masks a “necessary, if not life-saving, evil”. However, masks have been admired and worn throughout the world for centuries and play an integral part of many activities including customary rituals, cultural events, battles, entertainment, and for protection. They may hide identities, reveal certain personality traits, suggest moods, or act as a barrier between the wearer and the outside world. Masks and mask making has a striking number of similarities to dentistry, and so it seemed fitting to dedicate this year’s cover pages to various types of masks.https://www.sada.co.za/the-sadjam2022Prosthodontic

X-rays and virtual taphonomy resolve the first Cissus (Vitaceae) macrofossils from Africa as early diverging members of the genus

PREMISE OF THE STUDY: Fossilized seeds similar to Cissus (Vitaceae) have been recognized from the Miocene of Kenya, though some were previously assigned to the Menispermaceae. We undertook a comparative survey of extant African Cissus seeds to identify the fossils and consider their implications for the evolution and biogeography of Cissus and for African early Miocene paleoenvironments. METHODS: Micro-computed tomography (µCT) and synchrotron-based X-ray tomographic microscopy (SRXTM) were used to study seed morphology and anatomy. Virtual taphonomy, using SRXTM data sets, produced digital fossils to elucidate seed taphonomy. Phylogenetic relationships within Cissus were reconstructed using existing and newly produced DNA sequences for African species. Paleobiology and paleoecology were inferred from African nearest living relatives. KEY RESULTS: The fossils were assigned to four new Cissus species, related to four modern clades. The fossil plants were interpreted as climbers inhabiting a mosaic of riverine woodland and forest to more open habitats. Virtual taphonomy explained how complex mineral infill processes concealed key seed features, causing the previous taxonomic misidentification. Newly sampled African species, with seeds most similar to the fossils, belong to four clades within core Cissus, two of which are early diverging. CONCLUSIONS: Virtual taphonomy, combined with X-ray imaging, has enabled recognition of the first fossil Cissus and Vitaceae from Africa. Early-divergent members of the core Cissus clade were present in Africa by at least the early Miocene, with an African origin suggested for the Cissus sciaphila clade. The fossils provide supporting evidence for mosaic paleoenvironments inhabited by early Miocene hominoids

Methane emissions from oil and gas platforms in the North Sea

Since 1850 the concentration of atmospheric methane (CH4), a potent greenhouse gas, has more than doubled. Recent studies suggest that emission inventories may be missing sources and underestimating emissions. To investigate whether offshore oil and gas platforms leak CH4 during normal operation, we measured CH4 mole fractions around eight oil and gas production platforms in the North Sea which were neither flaring gas nor offloading oil. We use the measurements from summer 2017, along with meteorological data, in a Gaussian plume model to estimate CH4 emissions from each platform. We find CH4 mole fractions of between 11 and 370 ppb above background concentrations downwind of the platforms measured, corresponding to a median CH4 emission of 6.8 g CH4 s−1 for each platform, with a range of 2.9 to 22.3 g CH4 s−1. When matched to production records, during our measurements individual platforms lost between 0.04 % and 1.4 % of gas produced with a median loss of 0.23 %. When the measured platforms are considered collectively (i.e. the sum of platforms' emission fluxes weighted by the sum of the platforms' production), we estimate the CH4 loss to be 0.19 % of gas production. These estimates are substantially higher than the emissions most recently reported to the National Atmospheric Emission Inventory (NAEI) for total CH4 loss from United Kingdom platforms in the North Sea. The NAEI reports CH4 losses from the offshore oil and gas platforms we measured to be 0.13 % of gas production, with most of their emissions coming from gas flaring and offshore oil loading, neither of which was taking place at the time of our measurements. All oil and gas platforms we observed were found to leak CH4 during normal operation, and much of this leakage has not been included in UK emission inventories. Further research is required to accurately determine total CH4 leakage from all offshore oil and gas operations and to properly include the leakage in national and international emission inventories

Multimodality imaging with CT, MR and FDG-PET for radiotherapy target volume delineation in oropharyngeal squamous cell carcinoma

Background: This study aimed to quantify the variation in oropharyngeal squamous cell carcinoma gross tumour volume (GTV) delineation between CT, MR and FDG PET-CT imaging. Methods: A prospective, single centre, pilot study was undertaken where 11 patients with locally advanced oropharyngeal cancers (2 tonsil, 9 base of tongue primaries) underwent pre-treatment, contrast enhanced, FDG PET-CT and MR imaging, all performed in a radiotherapy treatment mask. CT, MR and CT-MR GTVs were contoured by 5 clinicians (2 radiologists and 3 radiation oncologists). A semi-automated segmentation algorithm was used to contour PET GTVs. Volume and positional analyses were undertaken, accounting for inter-observer variation, using linear mixed effects models and contour comparison metrics respectively. Results: Significant differences in mean GTV volume were found between CT (11.9 cm³) and CT-MR (14.1 cm³), p < 0.006, CT-MR and PET (9.5 cm³), p < 0.0009, and MR (12.7 cm³) and PET, p < 0.016. Substantial differences in GTV position were found between all modalities with the exception of CT-MR and MR GTVs. A mean of 64 %, 74 % and 77 % of the PET GTVs were included within the CT, MR and CT-MR GTVs respectively. A mean of 57 % of the MR GTVs were included within the CT GTV; conversely a mean of 63 % of the CT GTVs were included within the MR GTV. CT inter-observer variability was found to be significantly higher in terms of position and/or volume than both MR and CT-MR (p < 0.05). Significant differences in GTV volume were found between GTV volumes delineated by radiologists (9.7 cm³) and oncologists (14.6 cm³) for all modalities (p = 0.001). Conclusions: The use of different imaging modalities produced significantly different GTVs, with no single imaging technique encompassing all potential GTV regions. The use of MR reduced inter-observer variability. These data suggest delineation based on multimodality imaging has the potential to improve accuracy of GTV definition. Trial registration: ISRCTN Registry: ISRCTN34165059. Registered 2nd February 2015

Smoking in asthma is associated with elevated levels of corticosteroid resistant sputum cytokines—an exploratory study

&lt;p&gt;Background: Current cigarette smoking is associated with reduced acute responses to corticosteroids and worse clinical outcomes in stable chronic asthma. The mechanism by which current smoking promotes this altered behavior is currently unclear. Whilst cytokines can induce corticosteroid insensitivity in-vitro, how current and former smoking affects airway cytokine concentrations and their responses to oral corticosteroids in stable chronic asthma is unclear.&lt;/p&gt; &lt;p&gt;Objectives: To examine blood and sputum cytokine concentrations in never, ex and current smokers with asthma before and after oral corticosteroids.&lt;/p&gt; &lt;p&gt;Methods: Exploratory study utilizing two weeks of oral dexamethasone (equivalent to 40 mg/day prednisolone) in 22 current, 21 never and 10 ex-smokers with asthma. Induced sputum supernatant and plasma was obtained before and after oral dexamethasone. 25 cytokines were measured by multiplex microbead system (Invitrogen, UK) on a Luminex platform.&lt;/p&gt; &lt;p&gt;Results: Smokers with asthma had elevated sputum cytokine interleukin (IL) -6, -7, and -12 concentrations compared to never smokers with asthma. Few sputum cytokine concentrations changed in response to dexamethasone IL-17 and IFNα increased in smokers, CCL4 increased in never smokers and CCL5 and CXCL10 reduced in ex-smokers with asthma. Ex-smokers with asthma appeared to have evidence of an ongoing corticosteroid resistant elevation of cytokines despite smoking cessation. Several plasma cytokines were lower in smokers wi&lt;/p&gt; &lt;p&gt;Conclusion: Cigarette smoking in asthma is associated with a corticosteroid insensitive increase in multiple airway cytokines. Distinct airway cytokine profiles are present in current smokers and never smokers with asthma and could provide an explanatory mechanism for the altered clinical behavior observed in smokers with asthma.&lt;/p&gt

Humanity’s Best Friend: A Dog-Centric Approach to Addressing Global Challenges

No other animal has a closer mutualistic relationship with humans than the dog (Canis familiaris). Domesticated from the Eurasian grey wolf (Canis lupus), dogs have evolved alongside humans over millennia in a relationship that has transformed dogs and the environments in which humans and dogs have co-inhabited. The story of the dog is the story of recent humanity, in all its biological and cultural complexity. By exploring human-dog-environment interactions throughout time and space, it is possible not only to understand vital elements of global history, but also to critically assess our present-day relationship with the natural world, and to begin to mitigate future global challenges. In this paper, co-authored by researchers from across the natural and social sciences, arts and humanities, we argue that a dog-centric approach provides a new model for future academic enquiry and engagement with both the public and the global environmental agenda

Estimating the Location and Spatial Extent of a Covert Anthrax Release

Rapidly identifying the features of a covert release of an agent such as anthrax could help to inform the planning of public health mitigation strategies. Previous studies have sought to estimate the time and size of a bioterror attack based on the symptomatic onset dates of early cases. We extend the scope of these methods by proposing a method for characterizing the time, strength, and also the location of an aerosolized pathogen release. A back-calculation method is developed allowing the characterization of the release based on the data on the first few observed cases of the subsequent outbreak, meteorological data, population densities, and data on population travel patterns. We evaluate this method on small simulated anthrax outbreaks (about 25–35 cases) and show that it could date and localize a release after a few cases have been observed, although misspecifications of the spore dispersion model, or the within-host dynamics model, on which the method relies can bias the estimates. Our method could also provide an estimate of the outbreak's geographical extent and, as a consequence, could help to identify populations at risk and, therefore, requiring prophylactic treatment. Our analysis demonstrates that while estimates based on the first ten or 15 observed cases were more accurate and less sensitive to model misspecifications than those based on five cases, overall mortality is minimized by targeting prophylactic treatment early on the basis of estimates made using data on the first five cases. The method we propose could provide early estimates of the time, strength, and location of an aerosolized anthrax release and the geographical extent of the subsequent outbreak. In addition, estimates of release features could be used to parameterize more detailed models allowing the simulation of control strategies and intervention logistics

Science opportunities with solar sailing smallsats

Recently, we witnessed how the synergy of small satellite technology and solar sailing propulsion enables new missions. Together, small satellites with lightweight instruments and solar sails offer affordable access to deep regions of the solar system, also making it possible to realize hard-to-reach trajectories that are not constrained to the ecliptic plane. Combining these two technologies can drastically reduce travel times within the solar system, while delivering robust science. With solar sailing propulsion capable of reaching the velocities of ~5-10 AU/yr, missions using a rideshare launch may reach the Jovian system in two years, Saturn in three. The same technologies could allow reaching solar polar orbits in less than two years. Fast, cost-effective, and maneuverable sailcraft that may travel outside the ecliptic plane open new opportunities for affordable solar system exploration, with great promise for heliophysics, planetary science, and astrophysics. Such missions could be modularized to reach different destinations with different sets of instruments. Benefiting from this progress, we present the "Sundiver" concept, offering novel possibilities for the science community. We discuss some of the key technologies, the current design of the Sundiver sailcraft vehicle and innovative instruments, along with unique science opportunities that these technologies enable, especially as this exploration paradigm evolves. We formulate policy recommendations to allow national space agencies, industry, and other stakeholders to establish a strong scientific, programmatic, and commercial focus, enrich and deepen the space enterprise and broaden its advocacy base by including the Sundiver paradigm as a part of broader space exploration efforts.Comment: 34 pages, 12 figures, 2 table