From the Wikipedia Rabbit Hole Day Trip: Bacterial Cellulose

Lightenoughtotravel, Public domain, via Wikimedia Commons

The equivalent of cellulose in other plants (e.g. wood formed from lignin fibres in trees), but made by bacteria. So just like plant cells have a cellulose shell to give them protection and structural integrity, bacteria have something similar. I ended up on this page because I was reading on a homemade tools group about how someone had used the stuff in the same way leather is used, for strapping two parts together. Bacterial cellulose has certain desirable characteristics such as greater tensile strength than plant cellulose and large hydrophilicity (attraction to water) and so may be useful in biomedical applications.

More info in this Wikipedia article.

#MaterialsScience

Arc Flashes

Zaereth, CC BY-SA 4.0, via Wikimedia Commons

Which can cause severe burns. The arc is usually hotter than the surface of the Sun and has the energy of an explosion. A conductive arc can form due to dust, faulty components or shorted terminals in an electrical panel due to a dropped tool. Another cause can be improperly placed test leads which bridge live parts. The huge surge in current through the low resistance arc can lead to catastrophic injuries and damage in the milliseconds before a protective device operates. Personnel working on electrical panels use PPE to protect themselves from the heat and intense UV of an arc flash. See this Fluke guide for more details.

Science With Dr Karl Podcast — Heterochromia, Cold Water Therapy and Time of Death

Dr Karl is on sabbatical, but Bianca Nogrady joins Lucy Smith to answer listeners' questions about having different colour eyes, could we evolve to become fish people and plant cancers. We also learn about a new pump to replace the heart that runs continuously and doesn't beat like a normal heart.You can listen to the latest episode here.

Bicycle Wheel Bearing Maintenance

Bicycle hub with traditional cup and cone bearings © Eugene Brennan.

So the back wheel on my bike was making grinding noises on the way back from my cycle along the canal to Sallins last Sunday. These rims are 1997 vintage and older wheels have cup-and-cone bearings. The advantage of these is that the parts can be easily replaced when they wear: the axle, the cones and the steels balls the cones turn against. Unfortunately they're also prone to grit and grime getting into the bearing, especially when a hose or power washer is used to wash muck off a bike, as this can drive the stuff inside. Newer hub bearings are sealed and probably use roller or ball bearings. However when the bearing wears, the whole wheel has to be replaced. The hub and axle alone can be replaced, but it means undoing all the spokes, then rebuilding the wheel with the new hub and replacing the spokes, which is not a job for amateurs. That's because all the spokes have to be properly tensioned to ensure trueness of the wheel.

I cleaned all the balls from the bearing (a magnetic pick-up tool is the best way of getting them out of the grease), the cones and the cups which are bowl-shaped steel inserts in the aluminium hub. Neither were excessively pitted nor worn. The axle was a bit bent, but that often happens due to impacts with a bad road surface and applying too much force to pedals when climbing steep hills. Then I re-greased everything and put the bearing back together. It's still a bit rough, but should last for another while. I have a spare pair of new sealed bearing wheels to act as replacements.

Spacer to accommodate freewheel cogs. © Eugene Brennan

Components from bearing. © Eugene Brennan

Trainee bicycle mechanic. © Eugene Brennan

Cup part of cup and cone bearing. © Eugene Brennan

 

Septic Tank Inspections

Schematic of a septic tank. Image courtesy Tilley, E., Ulrich, L., Lüthi, C., Reymond, Ph., Zurbrügg, C., CC BY-SA 4.0 , via Wikimedia Commons

The smell of overflowing septic tanks is something I encounter regularly, cycling the highways and byways of Kildare. Two incidences yesterday in the Suncroft area and one close to Narraghmore Game Reserve. Maybe there are other issues that cause smell though like bad drainage or older systems that don't agitate the contents of the tank? Agitation increases the oxygen content of liquid in a septic tank, improving the rate of aerobic bacterial growth and speeding up the digestion of sewage. This recent article from the Kildare Nationalist by Finian Coghlan fills us in with the details of the inspections.

Plate Tectonics and Finger Nails

Image created using by Bing Image Creator.

Plate tectonics is a theory, superseding and encompassing the earlier continental drift theory, that the Earth's continents make large scale movements over geological time. The process is really slow, and occurs at the same rate finger nails grow: about 0.1 mm a day. That's 36.5 mm a year, 36.5 m per millennium and 36.5 km per million years or 3650 km in 100 million years. Ireland, or more correctly the parts that make up Ireland, were once located south of the equator in tropical seas. (I found a rock once in the midlands, when helping to dig a deep hole. The rock was embedded with large fossilised cockles). Over millions of years the parts drifted northward and merged, to make the island. The dividing line between the northern and southern parts of the island of Ireland runs roughly down a line between Louth and Kerry.

Force Between Magnets Over a Distance

Public domain image via Pixabay

As you probably know, like poles of magnets repel and unlike poles attract. The force between two magnets increases as they're brought closer together, but how does it vary? Many things in nature follow an inverse square law. So the luminous intensity of an omnidirectional (the same in all directions) light source or loudness of an omnidirectional sound source follows an inverse square law. If you move 3 times further away from a sound than your original position, the loudness reduces by a factor of 9. At 100 times the original distance, the loudness reduces by 100 x 100 =10,000 times. Similarly for the brightness of a light. That's because the sound or light flux is passing through an imaginary sphere and the surface area of a sphere depends on the square of its radius (4πr²). In this Quora post, we discover that for a magnet, the scenario is a lot more complicated because fields aren't uniformly shaped.

Tree Manslaughter

Dead apricot tree. © EugeneBrennan

So I tied a rope around a limb of this apricot tree that I grew from a stone around 2003, because it was growing across the driveway and the rope was to pull it inwards. Nothing wrong with that and usually you thread the rope through something soft like a scrap of garden hose so it doesn't damage the bark. Then over time, the tension normally goes out of the limb and it stays in place and the rope can be removed. However I left the rope in place, thinking it would be swallowed by the bark, just like what sometimes happens to park benches and the vascular channels in the bark would merge and create a bypass for sap. But apparently not. What happens is that a tree actually gets strangled as the trunk expands and flow of sap and nutrients can't get past the bottleneck. So I queried it on a Facebook gardening group and was accused of murder and was lucky to escape without being virtually lynched.

I think the tree looks nice though even though it's dead.

© Eugene Brennan

Ardnacrusha to Dublin Transmission Line and Mystery Engine House

Image courtesy Military Archives.

Just noticed the base of one of the pylons of the 110 kV line from Ardnacrusha to Dublin in the top left of this photo of Kilcullen Bridge from the military archives (Click on the link in the image caption to open the image viewer which has a zoom facility). Ardnacrusha hydro-electric power station was commissioned in 1929, and presumably the transmission line dated from then. The line was dismantled in the 60s or maybe early 70s? When the photo was taken, power was delivered directly from Newbridge/Kildare to Kilcullen at 10 kV and there's a transformer in Nugent's field for dropping voltage from that 10 kV to around 230 V. There was no substation in the town at the time, or at least when the last edition 6" OSI map shown was drafted. The map is post-1939 as the Nicholastown housing estate has been built. The 38 kV station at Sunnyhill we have now is fed from the 110 kV substation on the N81 near Stratford-on-Slaney.

The record in the archives at the link below also has an aerial view of the bridge looking south. On desktop/laptop, right click and open the image in a new tab to view at full size. There isn't a zoom facility in the viewer.
I still haven't found out what was housed in the "Engine Ho.", located approximately where Scoil Bhríde is now. A stationary engine for pumping water from a well for the convent? Or maybe a machine for making meal for feeding animals on the convent "farm"? Or did the convent have their own electricity and this was where the engine and generator was located? Maybe someone knows.

Image courtesy Tailte Éireann (OSI)

 

Well Fancy That!

St Brigid's Well, Kilcullen. © Eugene Brennan

KCA have added a nice new gravel ramp leading up to the bottom step at St. Brigid's Well which will help us older or short-legged folk negotiate the incline. The riser of the step was always quite tall. The others are a bit tall too. The gravel ramp should be safer than the existing stone one which is probably risky in the winter because of ice and algae. The steps are somewhat slippy, possibly because the hard rock has become worn and polished from traffic. In winter the situation is worse because of algae, but KCA (I presume) have regularly sanded the steps which helped and made them safe

St Brigid's Well, Kilcullen. Ramp added to reduce step height. © Eugene Brennan

On This International Women's Day, Remembering Irish Pioneers of Science and Technology

Jocelyn Bell Burnell, Kathleen Lonsdale, Mary Parsons, Kay McNulty and Mary Ward. See below for Image attributions.

 

Jocelyn Bell Burnell (1943 - ) who as a graduate student, discovered astronomical objects called pulsars in 1967.

 

Kathleen Lonsdale (1903 – 1971), a crystallographer from Newbridge, who used new techniques such as X-ray diffraction and Fourier spectral methods to investigate hydrocarbons. She was also the first woman to become a member and president of several male-dominated scientific institutions.

 

Mary Parsons, Countess of Rosse (1813 – 1885). An amateur astronomer and blacksmith and a pioneer in making photos from wax paper negatives.

 

Kay McNulty (1921 – 2006) Software engineer and one of the six original programmers of ENIAC, a room-sized early computer, used by the US military to calculate artillery firing tables.

 

Mary Ward (1827 –1869) Naturalist, amateur astronomer, microscopist, author, and artist who wrote several books about her discoveries in microscopy including A World of Wonders Revealed by the Microscope.

 

Image attributions:

 

Photo of Jocelyn Bell Burnell at Launch_of_IYA_2009,_Paris_-_Grygar,_Bell_Burnell.jpg: Astronomical Institute, Academy of Sciences of the Czech Republic derivative work: Anrie, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons.

 

Photo of Kay McNulty by Zebbie, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

 

All other images, public domain.

How Much Does the Length of a Day Vary By?

Created with Bing Image Creator.

Every four years we have a leap year and an extra day is added to the calendar in February. That's because the time it takes for the Earth to orbit the Sun is approximately 365.25 days. Considering the Earth's orbit as approximately a circular path around the Sun, If we didn't compensate for the extra quarter day, the Earth would end up being a little short of a full 360 degrees of its way around the Sun on the 31st December (a quarter day short). Eventually 31st of December would fall earlier and earlier in the seasons until it ended up in the summer. By adding an extra day every four years, the Earth is allowed to "catch up" in its orbit. Similarly, a day, or the time it takes the Earth to revolve on its axis isn't exactly 24 hours long and is influenced by environmental and geological events. In fact in 2025, the length of time between the longest and shortest day was approximately 1.6 mS. It mightn't seem like a lot, but to keep everything in sync, leap seconds have to be added onto Coordinated Universal Time (UTC) every so often. The leap second was introduced in 1972. The most recent leap second adjustment was in December 31, 2016. However leap seconds are controversial and cause issues with critical systems that rely on accurate timekeeping. 

More info here.