Below you will find reports from our lectures. Either click the title to view the report online or download a copy by clicking on the file name next to 'Download report'. Use the search box on this page to find a particular report.
The tenacity and shear optimism of space scientists is really admirable. They put a lot of effort into developing the proposal for an experiment on a spacecraft (most get rejected) then they spend years developing instruments which need to be at the forefront of technology, but they have to use spacequalified electronic components which are necessarily using decade-old technology. After maybe ten years of work they put their precious baby on top of a rocket which may explode or crash if any one of hundreds of thousands of components working at their limits of endurance do not behave perfectly. Then, as in the case of Rosetta, and assuming the launch is successful they wait maybe another ten years while the space craft finds its way across half the Solar System to an almost invisible lump of black ice a few kilometres across and travelling at an extremely high speed. You then drop your delicate package onto an uneven, rock strewn surface, hoping that it will land somewhere safe…and manage to stick it down in an orientation where the instruments can do the job they were designed to do. If they don’t, well, there may be another space craft coming along in twenty years.
We have, I think, became rather too used to extraordinary space missions actually succeeding and forget what a white-knuckle ride most must be for those who bet entire careers on the chance of nothing going wrong. Well, Rosetta as a whole was an extraordinary success, though the Philae lander, for which Dr
Andrew Morse help design the Ptolemy mass spectrometer, did not work completely as expected, for it turns out to be very difficult to stick yourself down on a comet. The engineers were told that the surface might be anything from the consistency of candy-floss to hard concrete, and in fact it turned out to be an
impossible combination of both: a layer of extremely soft material overlaying exceptionally cold and very hard ice. None of the several hold-down methods managed to grab on, so Philae bounced across the surface, claiming, as Dr Morse pointed out, the first four landings on a comet. It finally ended up on its
side, in the shadow of a boulder, which meant that the solar panels could not recharge the batteries, so they were limited to a day or two of data gathering. Given all these formidable difficulties it highly impressive that about 80% of the science targets were accomplished. In fact, some of the technological wizardry for getting samples into the mass spectrometer turned out to be unnecessary, because the first impact kicked up so much dust that the instruments were able to sniff the composition while Philae was tumbling. Nevertheless, it is unlikely that this method will be adopted as the favoured method of collecting surface samples in the future.
We should not forget the science, which after all is why researchers go through this process. Comets are pretty much guaranteed to be the (more-or-less) unprocessed remnants of the original material out of which the Solar System formed. Everything else we can reach has been extensively cooked in various
ways. Of course, it is not quite that simple: comets may have been sitting a few degrees above absolute zero for four and half billion years (not an environment is which we expect chemistry) but have also been exposed to a small but significant flux of high energy cosmic rays for all that time. Their surfaces (as
Philae confirmed) may consist of various polymerisations of the low concentration basic organic compounds (e.g. methane) that form part of the bulk composition. That is probably why they are so black - think of the bottom of a pan left on the cooker for far too long. However, as the comet approaches the Sun and heats up, volatile material from below the surface evaporates and emerges as jets, which can be sampled by the Rosetta orbiter. Rosetta shut down in 2015, its mission accomplished, but the science goes on and will go on, no doubt until the next spacecraft attempt a comet landing (maybe in twenty years from now?) because the data from Rosetta is unique and of enormous importance to those who seek to understand the original of the Solar System.
Dr Morse presented the society with a fascinating and extremely well illustrated lecture on the work of this exploratory space project.
- Category: Lecture Reports
- Date: Wednesday, 9 Jan 2019
- Dr. Andrew Morse
- Open University
- Download Report: The_Rosetta_Mission.pdf
Metals in Medicine – The Use of Stents
Derek Edwards, The Christie Institue
What is the connection between American fighter jets and the Christie Centre in Manchester? Answer: they both make use of memory shape alloys.
NiTiNOL is a remarkable material: it is super-elastic (you can stretch it, and stretch it….) and it then always returns to its previous shape (a shape that you can set by heating it to 500 degrees Centigrade while holding it in the desired configuration). Combine these properties with corrosion resistance and bio-compatibility and you have a highly desirable material for use in medical stents. The memory-shape ability and elasticity means that a stent designed to hold open a body passage (such as the Oesophagus or the bile duct) can be compressed inside a small tube that can be fed down to the target location. When the stent is pushed out of the insertion device it expands back to its original dimensions (preferably somewhat gently) and, for example, now provides a route for food to patients who previously had difficulty swallowing.
The Christie, supported by Derek Edwards, make use of stents to provide palliative care for sufferers from Oesophageal cancer, but to some extent they have been victims of their own success in extending life.
Patients are surviving sufficiently long for them to discover that NiTiNol is not quite as corrosion resistant to stomach acids as they at first thought, and they have now had to develop sophisticated methods of removing stents that after many months are starting to break up. This looked like a decidedly non-trivial process, because spreading cancers can grow around the stent wires. The search is on for more resistant materials that can also retain the highly desirable properties of NiTiNOL (e.g. by coating the wire in platinum).
Derek Edwards was clearly a man overflowing with enthusiasm for his work (for which, being formally in retirement, he no longer gets paid - as a matter of choice), but it is clearly an all consuming activity that he will never be able to leave alone, and for which we should all be highly grateful.
- Category: Lecture Reports
- Date: Wednesday, 12 Dec 2018
- Derek Edwards
- Download Report: Metals_in_Medicine_-_Use_of_Stents.pdf
Who would have thought that silk made good armour! The Mongul horsemen, however, had discovered
that wearing a tight silk vest meant that the barbed and faeces-smeared arrow heads of their opponents never
had a chance to lodge in and infect their flesh. Modern bomb disposal operatives wear silk pants for
similar reasons: if they are unfortunately caught in an explosion the silk prevents dust and dirt from
penetrating through their skin. Silk is both exceptionally tough and strong, beating every other polymer
(natural and artificial) about which we know.
It has, at times, also been exceptionally valuable, particularly in countries at the far end of the “silk
road”: literally worth its weight in gold, and a full silk costume might have cost the price of the palace. For
a period of 200 years, 50% of Venetian tax revenues came from silk production and skilled silk weavers
were forbidden to leave the city on pain of death. Even today, cultivating silk worms produces
exceptionally high returns per unit area of land, and requires only modest capital investment.
Furthermore, produce is not confined to China and can be found today in Rumania and Bulgaria. (Our
own Queen had a dress made entirely from UK produced silk.)
Spider silk is even more remarkable than the product of the mulberry silk worm: it comes in seven
different varieties - each used for different purposes such as structural parts of a web (strong and flexible)
for catching flies (sticky and extensible) or making egg cases (soft and protective). Unlike mulberry worm
silk it is exceptionally difficult to produce in commercial quantities (you need to a tethered live spider from
which to draw the silk) and would be currently valued at millions of dollars per kilogram.
Bioengineering start-ups are, of course, trying to reproduce the complex polymer structure of spider silk
using, for example, genetically engineered micro-organisms, which, however, as yet only produce short
strands of rather simpler amino acid combinations - and having not at all the same properties as the real
thing. Great commercial prizes await those who succeed because there are many valuable uses for such
a unique material.
Prof Volrath completed his exceptionally interesting talk by discussing recent work on regeneration of
nerves using silk frameworks. Nerves do like to regrow when damaged, but may not know in which
direction they should be moving. It has been shown, however, in a number of cases that packing an
excised vein with spider silk and then laying it along a damaged nerve track does encourage growth
along the silk fibres, and in a few cases has been demonstrated to lead to recovery of muscle control
after exceptional injuries to arms and legs.
- Category: Lecture Reports
- Date: Wednesday, 14 Nov 2018
- Prof. Fritz Volrath
- Professor of Zoology, Oxford University
- Download Report: Silk_lecture_.pdf
The idea to electrify the Great Western Railway was a political gesture. The Department for Transport was given the task of funding it and seeing it completed. The execution of the task was asigned to Network Rail, working through contractors.
The Objective was to shorten the journey time from Bristol to Paddington by 18 minutes, additionally by having faster trains, greater line capacity could be achieved and by lengthening the trains and making them run by electricity rather than diesel, greater seating capacity could be achieved as well as less pollution and less C02 emissions were realised. The plan was to extend the trains to Cardiff (end of 2019), Oxford and Newbury.
On completion, three Asset Heads would "own" the railway. One for signalling, one for track and one for the electrical infrastructure. The speaker's role was as a sponsor for Department for Transport to the 3 asset heads, while being employed by Network Rail.
On embarking on the project, mammoth problems were soon discovered. Bristol acted as a nidus for many of these. The track and signalling in East Bristol were antiquated. Extinct freight marshalling yards still fed onto the mainline through points resulting in speed restrictions. The signalling was of a similar age and was in need of replacing. There was a need to quadruple the tracks from Bristol Temple Meads up Filton Bank towards Parkway to cope with the increased traffic demand and a new platform needed to be constructed at Parkway. In addition to this, the line needed to be electrified.
Simply electrifying the line carried its own problems. The work had to be done while trains were running, which was unacceptable on safety grounds, so work had to be done at night, giving only 5 hours actual work, or possession had to be taken of a length of line for a period of time. This caused great inconvenience to passengers, freight operators, people using bridges, people who lived near the line and anyone who passed cables, crossings or water or services passing below the railway. Placing the gantries could prove difficult if the ground into which they were inserted differed. There was a mixture of clay, grouted embankments and bedrock to contend with.
Bridges posed problems with English Heritage demanding certain bridges be untouched. this necessitated lowering the track, which caused its own problems with profiling the track if near a station or junction. Similarly raised bridges had to be profiled which could lead to the road coming half way up someone's front door. Tunnels posed another problem. Box tunnel has 8 different species of bat living in its roof, all of which had to be considered when working in the tunnel. In addition to this a river was discovered one metre below the eatern portal, which required divers to survey.
Many lowered tracks fell below the drainage levels for the overall permanent way and this had to be dealt with. The moving parts of the system were also found to be problematical. A pantograph with carbon pick ups, contacts the round copper wire about 5 mm in diameter to transfer the current. The pressure of the wire on the pantograph was crucial and this was achieved by downdrop wires between the catenary and the pick up wire about evey metre. The length of these downdrop wires was different and crucial for the tension and pressure of the system. Despite this, the circular nature of the wire meant a pressure point on the pantograph until the wire developed "a flat". This shotened the life of the pantograph from its 8 week spec.
A decision was made that there was no immediate advantage to electrifying the line from Swindon to Bristol through Bath. This then necessitated the production of dual-traction (electro-diesel) five coach units. This then in turn put extra pressure on the maintenance depots to maintain a fleet of electro disel units and meant that there was extra energy expended in carrying diesel electric motors and the fuel to run them.
The final stage of the process is to commission the track and hand it over to the Asset Heads. This sounds a lot easier than it is in practice. So far, the railway is on schedule, Currently the line is electrified form Paddington to Didcot. This will be extended to just short of Swindon on October 21st this year and to Bristol by April 2019 and Cardiff by the end of 2019.
Many questions were asked throughout the presentation which was greatly enjoyed by those present.
- Category: Lecture Reports
- Date: Wednesday, 10 Oct 2018
- Jill Poyton B.Eng PgD
- Network Rail
- Download Report: GWR_Electrification_Talk.pdf