Today I Learned

[member 656954]

Today I actually looked at the PF icon and realized it's intention! Yes, I'm that slow

 

[Tom.G]

provided that we can be reassured that we can either eliminate enough of the moths

Many many todays ago I learned that Boric Acid (H₃BO₃) powder is extraordinarily effective against insects... it even kills off cockroaches! It's also less harsh to us Humans than the manufactured insecticides.

Some people here in the US have found it to work when sprinkled around before laying down carpet. Myself, I would also put a dusting on the carpet.

 

[BillTre]

External boric acid kills insects by abrading holes in their cuticle (largely chitin). The insect cuticle is water repellent and keeps the insect from drying out. Boric acid abrasions cause the insect to lose water and die.
The boric acid must be dry for this to work. Its small separate particles cause the abrasion.

We used it in fish facilties (which are a great environment for roaches) by putting it behind the drywall where the roaches often hid and nested.

 

[Tom.G]

External boric acid kills insects by abrading holes in their cuticle

That's the effect of Diatomaceous Earth (although I've found it not very effective for many bugs), could be a secondary effect of Boric Acid too. The reports I've been able to find on .GOV sites state the main route is when the cockroaches groom they eat the Boric Acid, which is poisonous. I proved the 'poisonous' once when I got some on a skinned knuckle and ignored it. My whole hand swelled up... so keep it out of open sores and don't eat it! Minor inhalation while applying hasn't caused me any noticeable effects, but I don't get careless about ventilation either.

Old-time fun fact(s): Boric Acid solution used to be used as an eye wash. Quite effective against some conditions. Don't know the concentration though. It's also effective in shoes as a deodorant and in gloves as a fungus killer.

 

[Klystron]

Boric acid dry powder is/was very effective against cockroaches infesting damp areas in otherwise dry desert xeriscape. Oddly, it became difficult to buy at nurseries that used to sell it by weight. Nursery management offered vague reasons implying that insecticide distributors or then-new Homeland Security (?) objected to this simple treatment.

Anecdotally, I have been told Borax dry hand soap works against roaches but is more expensive and less effective than the basic powder. Curious.

 

[symbolipoint]

Old-time fun fact(s): Boric Acid solution used to be used as an eye wash. Quite effective against some conditions. Don't know the concentration though.

From memory hearing an informal discussion, the solution was called "isotonic" in the characterization of the concentration.

 

[Tom.G]

From memory hearing an informal discussion, the solution was called "isotonic" in the characterization of the concentration.

That sounds vaguely familiar, which made me look it up... And to the rescue:
https://www.khanacademy.org/science/biology/membranes-and-transport/diffusion-and-osmosis/a/osmosis
In this case, meaning a solution that has the same osmotic pressure of solute as the solution within a cell does. Don't think I want to go down that rabbit hole, leave it to the chemists.

I have been told Borax dry hand soap works against roaches but is more expensive and less effective than the basic powder.

Different chemical. That stuff is Sodium Borate Decahydrate, a water softener as I recall.
(B₄Na₂O₇ · 10H₂O)

it became difficult to buy at nurseries that used to sell it by weight.

Yeah, I remember that. It is currently available in the nationwide Home Improvement hardware stores, displayed with the other insecticides. Sold in 1-pound squeeze-bottles for a few dollars.

 

[mfb]

Today I learned that $\frac{\sqrt{x^2+1}-1}{x} = \frac{x}{\sqrt{x^2+1}+1}$. Looks funny, but it works.

Spoiler

Found when reducing rounding errors for small x.
Context

 

[strangerep]

Today I actually looked at the PF icon and realized it's intention! Yes, I'm that slow

Today I read your post and realized I'd never even thought about PF icon. I've been a PF member a lot longer than you, so how slow does that make me?

 

[fresh_42]

Today I actually looked at the PF icon and realized it's intention! Yes, I'm that slow

Today I read your post and realized I'd never even thought about PF icon. I've been a PF member a lot longer than you, so how slow does that make me?

... and I still don't see what you mean. Could you enlighten me?

 

[Ibix]

... and I still don't see what you mean. Could you enlighten me?

It's a sort of atom-y thing inside a speech bubble - so "talking science" or "talking about science".

 

[fresh_42]

It's a sort of atom-y thing inside a speech bubble - so "talking science" or "talking about science".

Oh, that easy. I was looking for some message behind atoms with three valence electrons, or Lithium.

 

[strangerep]

I was looking for some message behind atoms with three valence electrons, or Lithium.

It's a good thing it wasn't a subtle message involving Uranium.

 

[fresh_42]

It's a good thing it wasn't a subtle message involving Uranium.

By the way: What do we have about the Lithium puzzle? Do we have an insight?

 

[Adesh]

By the way: What do we have about the Lithium puzzle? Do we have an insight?

But that's the classical model. Is our PF a classical forum?

 

[jbriggs444]

Today I learned that $\frac{\sqrt{x^2+1}-1}{x} = \frac{x}{\sqrt{x^2+1}+1}$. Looks funny, but it works.

Spoiler

Found when reducing rounding errors for small x.
Context

Back in high school while coding up a lunar landing game, I first encountered that issue and learned of the alternate quadratic formula: $$x=\frac{2c}{-b \pm \sqrt{b^2-4ac}}$$ which can evade the cancellation of near equal quantities and associated loss of precision.

 

[Jonathan Scott]

Today I learned that new sofas come with a chemical smell that irritates my nose and throat, and my wife hates the smell too. We left the windows open for hours (it was quite windy but only just above freezing outside) but it doesn't seem to have helped very much. I find it hard to believe that customers are really expected to put up with such an unpleasant experience, and I wouldn't be surprised if it is actually harmful to health.
I'm sure our previous ones weren't anything like so bad. Perhaps it's something to do with the"fire resistant" foam and materials, which were much less extreme 15 years ago. (No-one I know is a smoker so I can't see any benefit at all in fire resistance now). Our previous sofa had washable covers and cushions, but our new one cannot be cleaned properly at all (neither washed nor dry cleaned) because of some fireproofing treatment.
We deliberately avoided buying the "stain-proofing" treatment and insurance, mainly because of the ridiculous price (which made a mockery of the sale price of the sofa itself), but I guess that might well have made an even worse smell.

 

[fresh_42]

You should have bought a couch instead of a smell on fibers attached.

Maybe someone thought people would expect this, as they do in new cars. Btw. new airplanes have this smell of new like cars, too.

 

[strangerep]

By the way: What do we have about the Lithium puzzle? Do we have an insight?

Huh??

 

[fresh_42]

Huh??

I'm not totally sure, but isn't there a massive lack of Lithium in the universe?

 

[zoki85]

I'm not totally sure, but isn't there a massive lack of Lithium in the universe?

Humans are stealing it from the universe (for their cell phones and electric cars)

 

[Ibix]

Today I learned that if you start an email "Hi Jim. Please find attached..." and don't attach anything, Outlook will warn you that there are no attachments.

 

[Zantra]

Today I learned that at my advanced age with all the sum knowledge and experience that we'll probably never understand the nature of a woman. Some things are just not meant to be understood: )

 

[Adesh]

Humans are stealing it from the universe (for their cell phones and electric cars)

Some are stealing it for psychotic purpose too.

 

[Adesh]

Today I learned that I have become a PF electron. No idea what that metaphor means but I'm no longer a quark, haha!

 

[Ibix]

It's related to the points you get from trophies - I think estimated thresholds can be found on this thread (or at least in General Discussion) if you care to search.

 

[Adesh]

It's related to the points you get from trophies - I think estimated thresholds can be found on this thread (or at least in General Discussion) if you care to search.

What does electron signifies?

 

[Ibix]

Just that the number of trophy points you have is above a certain value. You probably got an alert about a trophy, for replying or posting a certain number of times or whatever. Noting that you have 22 trophy points, I guess "electron" is 20+. As I say, someone reverse engineered it - search General Discussion for posts containing ocean and mountain.

Edit: it doesn't mean we think negatively of you...

 

[strangerep]

TIL... that some people now abbreviate Starbucks -> Sbux.

(Hence I also learned that laziness is a monotonically increasing function of time).

 

[fresh_42]

TIL... that some people now abbreviate Starbucks -> Sbux.

(Hence I also learned that laziness is a monotonically increasing function of time).

And IBM employees probably use SBX.

 

[Adesh]

Today I learned that Freeman Dyson has died yesterday at the age of 96. Rest in peace!

 

[berkeman]

Today I learned that it's Stupid Leap Day today!

So I had made an appointment with the San Jose Household Hazardous Waste department for today to drop off some old motorcycle fluids and an old battery. I made the appointment online earlier this week, and thought I'd picked an 8AM Saturday dropoff appointment timeslot. I'd printed out the appointment and some other paperwork, and had it ready to go this morning.

But as I was putting the box of containers in the back of my vehicle to head down to the dropoff, I double-checked the appointment and saw 2/29/2020. But then I looked at my watch and saw 3/01, and I panicked. I started thinking, "How could I have been so stupid to make the appointment for Friday instead of Saturday? I wonder if they'll still let me do the dropoff today, or if I'll have to reschedule..."

So on the chance that they'd take pity on me and let me do the dropoff today instead of yesterday, I headed down the hill. When I got there right on time, I checked in with the guy at the gate, and was all apologetic saying that I think I messed up the appointment and it was for yesterday instead of today. He just asked for my name and checked me off the list for today (and I'm thinking WITW?), and waved me through to the dropoff spot.

I was happy that it went so smoothly (but still confused why I was on his printout list for today), and headed into work (yes it's Saturday). Now several hours later I notice online that today is Leap Day, and realized that my watch had automatically gone from 2/28 to 3/01. Lordy!

 

[fresh_42]

We have watches here which automatically synchronize with the official atomic clock ...

 

[Keith_McClary]

Today I re-learned from @berkeman that my watch does not understand leap days.

 

[hmmm27]

Today, I learned that 70% isopropanol is preferable to 99% for the purposes of disinfection.