Tag Archives: Royal Society

Seeing small changes is a big achievement

Figure 8 from Amjad et al 2022Some years ago I wrote with great excitement about publishing a paper in Royal Society Open Science [see ‘Press release!‘ on November 15th, 2017].  This has become a routine event; however, the excitement returned earlier this month when we had a paper published in the Proceedings of Royal Society of London on ‘A thermal emissions-based real-time monitoring system for in situ detection of cracks’.  The Proceedings were first published in February 1831 and this is only the second time in my career that my group has published a paper in them.  The last time was ten years ago and was also about cracks: ‘Quantitative measurement of plastic strain field at a fatigue crack tip’.  I have already described this earlier work in a post [see ‘Scattering electrons reveal dislocations in material structure’ on November 11th, 2020].  This was the first time that the size and shape of the plastic zone around a crack had been measured directly rather than inferred from other measurements.  It required an expensive scanning electron microscope and a well-equipped laboratory.  In contrast, the work in the paper published this month uses components that can be purchased for the price of a smart phone and assembled into a device not much larger than a smart phone.  The device detects the changes in the temperature distribution over the surface of the metal caused by the propagation of a crack due to repeated loading of the metal.  It is based on the principles of thermoelastic stress analysis [see ‘Counting photons to measure stress‘ on November 18th, 2015], which is a well-established measurement technique that usually requires expensive infra-red cameras.  Our key innovation is to not aim for absolute measurement values, which allows us to ignore calibration requirements, and instead to look for changes in the temperature distribution on the metal surface by extracting feature vectors from the images [see ‘Recognising strain‘ on October 28th 2015].  Our approach lowers the cost of the equipment required by several orders of magnitude, achieves comparable or better resolution of crack growth (around 1 mm) and will function at lower loading frequencies than techniques based on classical thermoelastic stress analysis.  Besides crack analysis, the common theme of the two papers is the innovative use of image processing to identify change, based on the fracture mechanics of crack propagation.

The research reported in this month’s paper was largely performed as part of the DIMES project about which I have written many posts.

The University of Liverpool was the coordinator of the DIMES project and the other partners were Empa, Dantec Dynamics GmbH and Strain Solutions Ltd.  Airbus was the topic manager on behalf of the Clean Sky 2 Joint Undertaking.

Logos of Clean Sky 2 and EUThe DIMES project received funding from the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 820951.

The opinions expressed in this blog post reflect only the author’s view and the Clean Sky 2 Joint Undertaking is not responsible for any use that may be made of the information it contains.

References:

Amjad, K., Lambert, C.A., Middleton, C.A., Greene, R.J., Patterson, E.A., 2022, A thermal emissions-based real-time monitoring system for in situ detection of cracks, Proc. R. Soc. A., doi: 10.1098/rspa.2021.0796.

Yang, Y., Crimp, M., Tomlinson, R.A., Patterson, E.A., 2012, Quantitative measurement of plastic strain field at a fatigue crack tip, Proc. R. Soc. A., 468(2144):2399-2415.

Image: Figure 8 from Amjad et al, 2022, Proc. R. Soc. A., doi: 10.1098/rspa.2021.0796.

Intelligent openness

Photo credit: Tom

As an engineer and an academic, my opinion as an expert is sought often informally but less frequently formally, perhaps because I am reluctant to offer the certainty and precision that is so often expected of experts and instead I tend to highlight the options and uncertainties [see ‘Forecasts and chimpanzees throwing darts’ on September 2nd 2020].  These options and uncertainties will likely change as more information and knowledge becomes available.  An expert, who changes their mind and cannot offer certainty and precision, tends not to be welcomed by society, and in particular the media, who want simple statements and explanations.  One problem with offering certainty and precision as an expert is that it might appear you are part of a technocratic subset seeking to impose their values on the rest of society, as Mary O’Brien has argued.  The philosopher Douglas Walton has suggested that it is improper for experts to proffer their opinion when there is a naked assertion that the expert’s identity warrants acceptance of their opinion or argument.  Both O’Brien and Walton have argued that expert authority is legitimate only when it can be challenged, which is akin to Popper’s approach to the falsification of scientific theories – if it is not refutable then it is not science.  An expert’s authority should be acceptable only when it can be challenged and Onora O’Neill has argued that trustworthiness requires intelligent openness.  Intelligent openness means that the information being used by the expert is accessible and useable; the expert’s decision or argument is understandable (clearly explained in plain language) and assessable by someone with the time, expertise and access to the detail so that they can attempt to refute the expert’s statements.  In other words, experts need to be  transparent and science needs to be an open enterprise.

Sources:

Burgman MA, Trusting judgements: how to get the best out of experts, Cambridge: Cambridge University Press, 2016.

Harford T, How to make the world add up: 10 rules for thinking differently about numbers, London: Bridge Street Press, 2020.

O’Brien M, Making better environmental decisions: an alternative to risk assessment, Cambridge MA: MIT Press, 2000.

Walton D, Appeal to expert opinion: arguments from authority, University Park PA: Pennsylvania State University Press, 1997.

Royal Society, Science as an open enterprise, 2012: https://royalsociety.org/topics-policy/projects/science-public-enterprise/report/

500th post

Map of all readership distributionThis is the five hundredth post on this blog.  The first 21 posts were published randomly between July 11th, 2012, and January 4th, 2013; and the weekly posts only started on January 7th, 2013, so I have another 48 posts to publish before I can claim a decade of weekly posts.  Nevertheless, I feel it is worth shouting about 500 posts.

I am a little surprised to realise that I have written five hundred posts and it has made me pause to think about why I write them.  A number of answers came to mind, including because I enjoy writing – it empties my mind and allows me to move on to new thoughts or, on other occasions, it allows me to arrange my thoughts into some sort of order.  I also write posts to communicate ideas, to disseminate research, to entertain and to fulfill a commitment, initially to funding bodies (I started the blog as part of commitment to Royal Society Wolfson Research Merit Award) but increasingly to readers of the blog.  I am amazed that for the last five years the blog has been read in more 140 countries.  While I have a handful of statistics about the readership, beyond the small handful of readers who correspond with me or who I meet in person, I have no idea who reads the blog.  Most of time I do not give much thought to who is reading my posts and my intended reader is a rather vague fuzzy figure who barely exists in my mind.

The map shows the distribution of all readers over the 500 posts with the darker colour indicating more readers per country.

Nano biomechanical engineering of agent delivery to cells

figure 1 from [1] with text explanationWhile many of us are being jabbed in the arm to deliver an agent that stimulates our immune system to recognize the coronavirus SARS-CoV-2 as a threat and destroy it, my research group has been working, in collaboration with colleagues at the European Commission Joint Research Centre, on the dynamics of nanoparticles [1] [see ‘Size matters‘ on October 23rd, 2019] which could be used as carriers for the targeted delivery of therapeutic, diagnostic and imaging agents in the human body [2].  The use of nanoparticles to mechanically stimulate stem cells to activate signalling pathways and modulate their differentiation also has some potential [3]. In studies of the efficacy of nanoparticles in these biomedical applications, the concentration of nanoparticles interacting with the cell is a primary factor influencing both the positive and negative effects.  Such studies often involve exposing a monolayer of cultured cells adhered to the bottom of container to a dose of nanoparticles and monitoring the response over a period of time.  Often, the nominal concentration of the nanoparticles in biological medium supporting the cells is reported and used as the basis for determining the dose-response relationships.  However, we have shown that this approach is inaccurate and leads to misleading results because the nanoparticles in solution are subject to sedimentation due to gravity, Brownian motion [see ‘Slow moving nanoparticles‘ on December 13th, 2017] and inter-particle forces [see ‘ Going against the flow‘ on February 3rd, 2021] which affect their transport within the medium [see graphic] and the resultant concentration adjacent to the monolayer of cells.  Our experimental results using the optical method of caustics [see ‘Holes in fluids‘ on October 22nd, 2014] have shown that nanoparticle size, colloidal stability and solution temperature influence the distribution of nanoparticles in solution.  For particles larger than 60 nm in diameter (about one thousandth of the diameter of a human hair) the nominal dose differs significantly from the dose experienced by the cells.  We have developed and tested a theoretical model that accurately describes the settling dynamics and concentration profile of nanoparticles in solution which can be used to design in vitro experiments and compute dose-response relationships.

References

[1] Giorgi F, Macko P, Curran JM, Whelan M, Worth A & Patterson EA. 2021 Settling dynamics of nanoparticles in simple and biological media. Royal Society Open Science, 8:210068.

[2] Daraee H, Eatemadi A, Abbasi E, Aval SF, Kouhi M, & Akbarzadeh A. 2016 Application of gold nanoparticles in biomedical and drug delivery. Artif. Cells Nanomed. Biotechnol. 44, 410–422. (doi:10.3109/21691401.2014.955107)

[3] Wei M, Li S, & Le W. 2017 Nanomaterials modulate stem cell differentiation: biological
interaction and underlying mechanisms. J. Nanobiotechnol. 15, 75. (doi:10.1186/s12951-
017-0310-5)