Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

L'Affaire Siloxane

mceglowski.substack.com

Post reply on HN
Print view View original

21–30 of 59 posts

Re: L'Affaire Siloxane

#21

Post by s0rce »

duskwuff wrote: post #14
s0rce wrote: post #10

Earlier quoted context omitted.

In medical device manufacturing you have systems in place that your vendors have to disclose changes to their manufacturing process that hopefully can catch stuff like this before people die. I can see how minute stuff gets easily passed off as not an important change.

Especially if the real change is a couple levels separated from the problem. For instance, I can imagine a situation where the manufacturer of that "special cloth" didn't even change anything themselves, but their lubricant supplier silently changed the formula of their sewing machine oil. (Or maybe even that one of the suppliers to the lubricant company changed something - it's turtles all the way down.)

Yes, you would also audit the quality system for your suppliers to confirm they are sufficiently controlling for upstream changes. In theory you can have all your ducks in a row.

Re: L'Affaire Siloxane

#22

Post by goodmythical »

wingmanjd wrote: post #18
shmeeed wrote: post #8

Part of my job is to keep siloxanes out of a complex, multi-step, multi-sub-contracted manufacturing process. A supplier change that should have been a simple affair has cost us several kilobucks in analyses in the past months. I hate the stuff.

This is the first time hearing the term "kilobucks". I love it (and am stealing it for future conversations).

I wish megabucks and gigabucks had the same ring...

Re: L'Affaire Siloxane

#23

Post by cubefox »

isoprophlex wrote: post #5
s0rce wrote: post #2

Siloxanes contaminate everything. We routinely see them on various surfaces when doing X-ray photoelectron spectroscopy.

Indeed. "Grease peaks" we called them, they were always there in basically all NMR or MS spectra I took as an organic chemist. Like PFAS or microplastics, you just can't get rid of them.

I bet some of these modern environmental contaminants is causing the increasing age cohort cancer rates.

Re: L'Affaire Siloxane

#24

Post by s0rce »

mrob wrote: post #17
isoprophlex wrote: post #5

Earlier quoted context omitted.

Indeed. "Grease peaks" we called them, they were always there in basically all NMR or MS spectra I took as an organic chemist. Like PFAS or microplastics, you just can't get rid of them.

You can see this grease by the effect it has on water contact angle. If you have a smooth glass/metal/ceramic surface, cleaned by a highly effective method (e.g. an ultrasonic cleaner), water poured on it will slide off easily without forming beads ("water-break test"). But if you leave it out in ordinary air for some time, the water will form beads again even if you never touch it. Exact time varies depending on air…

That's not always siloxanes, just atmospheric hydrocarbons.

Re: L'Affaire Siloxane

#25

Post by ggm »

I feel the microplastics contamination story which turns out to be measuring nitrile gloves used preparing samples is in this space. We can now measure things down to levels that may exceed our ability to exclude them as contaminants, routinely.

Re: L'Affaire Siloxane

#26

Post by mananaysiempre »

ggm wrote: post #25

I feel the microplastics contamination story which turns out to be measuring nitrile gloves used preparing samples is in this space. We can now measure things down to levels that may exceed our ability to exclude them as contaminants, routinely.

I’d say that has been true since we started using spectrometers (of all kinds). Those things are preposterously sensitive and pretty damn routine. Nowadays of course there are also other, more narrowly scoped detection methods as well, such as PCR.

Re: L'Affaire Siloxane

#27

Post by [deleted] »

s0rce wrote: post #21
duskwuff wrote: post #14

Earlier quoted context omitted.

Especially if the real change is a couple levels separated from the problem. For instance, I can imagine a situation where the manufacturer of that "special cloth" didn't even change anything themselves, but their lubricant supplier silently changed the formula of their sewing machine oil. (Or maybe even that one of the suppliers to the lubricant company changed something - it's turtles all the way down.)

Yes, you would also audit the quality system for your suppliers to confirm they are sufficiently controlling for upstream changes. In theory you can have all your ducks in a row.

[deleted]

Re: L'Affaire Siloxane

#28

Post by lugoues »

mannykannot wrote: post #16
RobotToaster wrote: post #3

> while a further 7,000 kilograms of treated urine were sitting in orbital storage tanks, waiting to be processed. Is that a record for the biggest piss bottle ever made?

A two meter cubed volume would be sufficient to hold that much. I would guess that cruise ships store more urine than that, though presumably not separated from everything else humans dump into toilets. With the qualification 'in orbit', I imagine it is.

I thought they just dumped it overboard but maybe there are some ethical cruises... maybe.

Re: L'Affaire Siloxane

#29

Post by ggm »

mananaysiempre wrote: post #26
ggm wrote: post #25

I feel the microplastics contamination story which turns out to be measuring nitrile gloves used preparing samples is in this space. We can now measure things down to levels that may exceed our ability to exclude them as contaminants, routinely.

I’d say that has been true since we started using spectrometers (of all kinds). Those things are preposterously sensitive and pretty damn routine. Nowadays of course there are also other, more narrowly scoped detection methods as well, such as PCR.

PCR/amplification is black magic. I'm also amazed by "no the DNA will be too old" keeps turning out not to be entirely true: People getting out of jail from re-testing evidence 20+ years later, Hominid DNA statements being made from archaic bones..

Animal population studies used to be (in my understanding) largely observational. Now, people can do scat tests and identify individuals.

Re: L'Affaire Siloxane

#30

Post by idlewords »

lugoues wrote: post #28
mannykannot wrote: post #16

Earlier quoted context omitted.

A two meter cubed volume would be sufficient to hold that much. I would guess that cruise ships store more urine than that, though presumably not separated from everything else humans dump into toilets. With the qualification 'in orbit', I imagine it is.

I thought they just dumped it overboard but maybe there are some ethical cruises... maybe.

It's fine to dump sewage overboard if you're far enough from shore. Cruise ships treat it to some extent, but ultimately it all becomes fish food.
Post reply on HN