Tag Archives: science

Salt increases nanoparticle diffusion

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About two and half years ago, I wrote about an article we had published on the motion of nanoparticles [see ‘Slow moving nanoparticles‘ on December 13th, 2017] in which we had shown that, for very small particles at low concentrations, the motion of a particle is independent of its size and does not flow the well-known Stokes-Einstein law.  Our article presented convincing evidence from experiments to support our conclusions but was light on explanation in terms of the mechanics.  At the end of last year, we published a short article in Scientific Reports, in which we demonstrated that the motion of nanoparticles at low concentrations is dependent on the interaction of van der Waals forces and electrostatic forces.  Van der Waals forces are short-range attractive forces between uncharged molecules due to interacting dipole moments, whereas the electrostatic forces are the repulsion of electric charges.  We changed both of these forces by using salt solutions of different concentration and observing the changes in nanoparticle behaviour.  Increasing the molarity increases the diffusion of the particles until the solution is saturated, as shown in the picture for 50 nanometre diameter gold particles (that’s about half the diameter of a coronavirus particle or one thousandth of the diameter of a human hair).  Our findings have implications for understanding the behaviour of nanoparticles dispersed in biological media, which typically contain salt in solution, because the concentration of salt ions in the medium affects nanoparticle diffusion that has been shown to influence cellular uptake and toxicity.

Sources:

Coglitore D, Edwardson SP, Macko P, Patterson EA, Whelan MP, Transition from fractional to classical Stokes-Einstein behaviour in simple fluids, Royal Society Open Science, 4:170507, 2017.

Giorgi F, Coglitore D, Curran JM, Gilliland D, Macko P, Whelan M, Worth A & Patterson EA, The influence of inter-particle forces on diffusion at the nanoscale, Scientific Reports, 9:12689, 2019.

Walking and reading during a staycation

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I am on vacation this week though, due to the restrictions on our movement imposed to prevent the spread of the coronavirus, it will a be staycation in our house.  We usually go to the Lake District at this time of year to walk and read; so, I might make another virtual expedition [see: ‘Virtual ascent of Moel Famau‘ on April 8th, 2020], perhaps to climb Stickle Pike and Great Stickle this time.  I was asked recently about books I would recommend prospective science and engineering students to read in preparation for to going to university.  It is not the first time that I have been asked the question.  This time I thought I should respond via this blog since the disruption brought about by the pandemic probably means that many prospective students will have more time and less preparation prior to starting their university course.  So, here are six books that are all available as ebooks, and might be of interest to anyone who is staying home to counter the spread of coronavirus and has time to fill:

[1] It is hard to find good novels either written by an engineer or about engineering [see ‘Engineering novelist‘ on August 5th, 2015]; however, Nevil Shute’s novel ‘Trustee from the toolroom‘ [Penguin Books, 1960] satisfies all of these criteria.

I have more than 40 years experience of engineering science so I am not the best person to ask about books that will appeal to young people just starting their journey in the field; however two books that have been popular recently are: [2] ‘Storm in a teacup: the physics of everyday life‘ by Helen Czerski [Penguin Books, 2016] and [3] ‘Think like an engineer‘ by Guru Madhavan [One World Publications, 2016]

Regular readers of this blog might have spotted some of my favourite science books in the lists of sources at the end of posts. Perhaps my top three at the moment are:

[4] Max Tegmark, Our Mathematical Universe, Penguin Books Ltd, 2014. [see: ‘Converting wealth into knowledge and back to wealth‘ on January 6th, 2016; ‘Trees are made of air‘ on April 1st, 2015; ‘Is the Earth a closed system? Does it matter?‘ on December 10th, 2014 & ‘Tidal energy‘ on September 17th, 2014]

[5] Susan Greenfield, A Day in the Life of the Brain, London: Allen Lane, 2016 [see: ‘Digital hive mind‘ on November 30th, 2016; ‘Gone walking‘ on April 19th, 2017 & ‘Walking through exams‘ on May 17th, 2017].

[6] Carlo Rovelli, The Order of Time, Penguin, 2019 [see: ‘We inhabit time as fish inhabit water’ on July 24th, 2019 and ‘Only the name of the airport changes‘ on June 12th, 2019].

Of course, I should not omit the books that I ask students to read for my own first year module in thermodynamics:

Peter Atkins, A very short introduction to thermodynamics, Oxford: OUP, 2010.

Manuel Delanda ‘Philosophy and Simulation: The Emergence of Synthetic Reason‘, London: Continuum Int. Pub. Group, 2011 [see: ‘More violent storms‘ on March 1st, 2017; ‘Emergent properties‘ on September 16th, 2015 & ‘Emerging inequality‘ on March 5th, 2014].

 

 

 

Devaluing novelty: not all that glitters is gold

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My regular readers will have recognised the novel nature of a blog that seeks, in a unique way, to present promising engineering ideas in a favourable and robust manner.  Actually, I hope my regular readers will recognise this opening sentence as completely uncharacteristic.  It was a blatant effort on my part to include the five words, underlined, with positive meanings that are most used in the titles and abstracts of articles published in clinical research and the life sciences.  A recent survey of more than 100,000 articles showed the prevalence of these words, with them being used significantly more in articles in which the first or last authors were male compared to those in which the first and last authors were female.  In other words, female authors are significantly less likely to describe their research findings in these positive terms and this influences the subsequent citations of their work and probably their prospects for research funding and advancement.  Sunday was International Women’s Day and, hence this is an appropriate week for everyone responsible for decisions about research to be conscious of this trend.  They should also be aware that the use of these positive words has increased in clinical and life sciences research by around 150% in the fifteen years to 2017.  In other words, the modesty of researchers has declined and they are more likely to describe their results as ‘novel’; however, I think it is unlikely that the results are any more novel than typical results published 20 years.  Of course, like most researchers, I always think my last breakthrough is the most exciting yet but many of us have been letting that enthusiasm lead us to exaggerate its novelty and value.

Source: Lerchenmueller MJ, Sorensen O & Jena AB, Gender differences in how scientists present the importance of their research: observational study, BMJ, 367:16573, 2019.

The Stone Raft adrift in the Atlantic Ocean

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I spent most of last week at the European Union’s Joint Research Centre in Ispra, Italy.  I have been collaborating with the scientists in  the European Union Reference Laboratory for alternatives to animal testing [EURL ECVAM].  We have been working together on tracking nanoparticles and, more recently, on the validity and credibility of models.  Last week I was there to participate in a workshop on Validation and Acceptance of Artificial Intelligence Models in Health.  I presented our work on the credibility matrix and on a set of factors that we have developed for establishing trust in a model and its predictions. I left the JRC on Friday evening and slipped back in the UK just before she left the Europe Union.  The departure of the UK from Europe reminds me of a novel by José Saramago called ‘The Stone Raft‘ in which the Iberian penisula breaks off from the Europe mainland and drifts around the Atlantic ocean.  The bureaucrats in Europe have to run around dealing with the ensuing disruption while five people in Spain and Portugal are drawn together by surreal events on the stone raft adrift in the ocean.