Chemistry

Researchers at the University of Bath have helped develop a graphene oxide membrane that could reduce the energy required to purify one of the chemical

Scientists have created twisted laser beams that interact differently with right-handed and left-handed molecules, revealing their identity through the fragments they produce. The approach could provide a faster, simpler, and more sensitive way to analyze important molecules used in chemistry and pharmaceuticals.

Searching the web for advice on attaching rubber to Ikea melamine has been dicey. PVA is said to not adhere well to non-porous surfaces like melamine, as I would expect. But then several articles say “use a good quality wood glue” and suggest particular brands. I thought wood glue is PVA, no? Maybe reputable proprietary brands are more than PVA, but I’m not interested in buying anything and generally not enthusiastic about paying for a brand’s reputation. Which means I’m not going to use the special-purpose melamine glue either.

I already have on-hand:

• contact cement
• construction adhesive
• expansion foam (which is like super glue IIUC, but the nozzle is clogged so I would rather avoid it); some articles say super glue is good for attaching rubber to melamine
• epoxy (as 2-component liquid)
• epoxy (as 2-component putty/filler+hardener)
• cheap generic wood glue
• PVA sold in 5 liter jugs for mixing with plaster or concrete

I am tempted to try the contact cement because it is intended for gluing two non-porous surfaces. Should I sand the melamine first? Obviously the answer is yes for epoxy, but contact cement is meant for non-porous surfaces.

To be clear, I am covering up the unsightely edge of Ikea melamine using an old bicycle tyre. The particle board edge is trivial and will have construction adhesive. As the tyre wraps aound the edge, there is about 10mm of rubber that must be glued to the melamine. Staples would work but I prefer to avoid them.

Author: Psarianos, Theresa knott

CC BY-SA 3.0

Author: Daniel Mayer

CC BY-SA 4.0

Abstract

Electrochemical production of fuels from solar energy, commonly referred to as solar-fuel production, is a key technology for converting abundant yet intermittent solar energy into a stable energy source. Typically, this process employs an electrolyzer coupled with photovoltaic (PV) cells through an electronic maximum power point tracking (MPPT) system. Here, we propose a chemical MPPT system, integrated directly into the electrolyzer, to enable stand-alone and unmanned liquid solar-fuel production with stabilized concentration changes from sunrise to sunset. The working principle of the MPPT system is derived from the impedance and heat-transfer properties of the electrolyzer, which incorporates a solid-state electrolyte exhibiting ionic resistivity with a negative temperature coefficient. Application of the mathematical model to a real electrolyzer energized by a commercially-available monocrystalline-Si PV panel for producing pure aqueous formic-acid solution demonstrated a high utilization factor (85%) of PV energy and a 2% external solar-to-formic-acid (eSTF) energy efficiency for 0.1 kg of formic acid from pure water and carbon dioxide (CO2) during daytime operation, all without the use of a conventional electronic MPPT system.

cross-posted from: https://lemmy.world/post/47979979

Paywall removed

I have a soft wet wood support beam, as described here. I bought some wood hardener. Instructions say to not apply to wet wood, only dry. I just wonder how that makes sense. I need the hardener liquid to penetrate the wood as much as possible. Water will creep along a wet surface better than a dry surface. I believe the wicking action of a wet surface will get the harder deeper into the wood. OTOH, they must have a reason for the guidance. Is it that the hardener would trap the water inside the wood fibers and be unable to escape?

If I use a hair dryer or something to dry the wood out as much as possible, is there anything I can do to improve the penetration of the hardener? I suppose I could make holes but of course that’s probably a bad idea in this case.

I should also mention that the hardener is water-based, which adds to my bafflement. The PDF says “Substrates must be cohesive, clean, sound and dry.” But the 2nd bullet on the webpage says “Adheres to damp wood”. Webpage also says “Surfaces: Can be applied to any types of woods, absorbent wood, dry or damp, including exotic species, chipboard and plywood sanded or stripped beforehand. ... Directions for use: Do not apply to soggy wood.”

It’s confusing but all their statements together seem to suggest it’s okay to apply to wet wood, but not ideal or optimal. Though my intuition would be to favor slightly damp wood to get wicking effects.

Forgive me, I know very little of chemistry.

The sewage pipe burst in the basement of the building I live in and my unit has been filled with, going by the symptoms, "healthy" 10-50 ppm levels of H2S and more stuff and the services have certainly been taking their time fixing it. In an act of desperation, I bought some bentonite clay in local pet store, put several kilograms of it into bin and started watering it since I read it could act as H2S adsorbent. I did that for a while. I also sprinkled sodium bicarbonate over it in case SO2+H20 was a reaction that occurred. First day I did it it worked great, but I'm not sure if the following times were anything but placebo. Yes, my mind didn't work very well when I did all of that.

I understand now that the only sane way to deal with this situation is to escape location. However, it occurs to me that if H2S simply adheres to the bentonite clay, somehow disturbing it will release it and I'm now left with several kilograms of hazardous material.

So, how do I dispose of it? Can I simply throw it away into urban trash collection system? Can I divide it into fist-sized chunks and throw it away over time? Can I safely cure H2S out of it?

Normally, I'd love to call my local hazardous materials disposal authority and have professionals handle it but I'm in Russia and doing such a fun call these times is likely to launch a chain of events where I end up somewhere in the trenches. Not an outcome I wish to bring about.

The rapid accumulation of plastic waste is currently posing significant risks for both human health and the environment on Earth. A possible solution to this problem would be to recycle plastic waste, breaking it into smaller molecules that can be used to produce valuable chemicals.

Researchers at Nanjing Forestry University and Tsinghua University recently introduced a new approach to convert polystyrene (PS), a plastic widely used to pack some foods and other products, into toluene, a hydrocarbon that is of value in industrial and manufacturing settings. Their proposed strategy, outlined in a paper published in Nature Nanotechnology, entails heating polystyrene waste in hydrogen and breaking it down into smaller vapor molecules, a process known as hydro-pyrolysis.

What are your thoughts on glove use in an organic chemistry lab setting?

I was trained from my Bachelor's to always wear gloves in lab unless using equipment and lab computers with clear instructions stating otherwise. Even in the safety course during my Ph.D., we discussed the benefits of wearing gloves as an extra layer of protection that buys time to reduce chemical exposure. No glove can behave as a barrier to all chemicals, but I was trained to be vigilant to chemical exposure on my gloves and remove them as quickly as possible.

I have recently joined another academic lab as a postdoc, and I learned that this chemistry department takes the exact opposite stance to glove safety. Here, gloves apparently only give researchers a false sense of security that can dull the sense of touch and prevent you from recognizing chemical exposure. This delay can then increase your chemical exposure as the chemical absorbs through the glove. I always see my labmates and others grab chemicals and solvents without gloves.

Before you get judgemental, I'm not a complete prude. I have been known to grab clean looking bottles and containers without gloves. But some of these people have been trained to the point where they are comfortable grabbing nasty ass bottles as if there isn't an increased risk.

Honestly, people can do what they want. I am mostly salty about the gentle reprimands I get every month of lab safety and my misuse of gloves.

https://en.wikipedia.org/wiki/Hexanitrogen

Hexanitrogen (diazide, hexaaza-1,2,4,5-tetraene) is an allotrope of nitrogen with the formula N6. The six nitrogen atoms are all covalently bonded in a single molecule: two azide units linked to each other. Its stability and structure were theorized in 2016 and its synthesis was reported in 2025. It is stable at cryogenic temperatures.

Four Thieves Vinegar Collective talking about building medications DIY on CCC, shared on kolektiva.media.

cross-posted from: https://lemmy.dbzer0.com/post/52150351

My bicycle was simply sitting at rest indoors when it exploded. A slit about ~6mm long was in the tube. I thought it might be too big to patch, but I happen to have some quit big patches to try. I cleaned the area w/denatured alcohol then roughened the surface w/the sanding tool. I covered the whole patch footprint area with rubber cement. Around 90 sec. later applied the patch and lightly clamped it down. About 5 min later: installed the tube and inflated to 4.5 bar.

Couple min later it exploded again. As the image shows, it blew exactly along the line of the original slit. AFAICT, I could not have applied this patch better. That is, the air went through the patch instead of around it.

Why did this happen? The patch is thicker and harder than the tube. So if the adhesive does its job well, then I would expect the patch to be stronger than the rest of the tube. The elasticity is lower in the patch, so I suppose that must be the problem.

So I have to wonder: would it be more or less effective to cut previously damaged spare tubes to use for patching, instead of a patch? I wonder if larger holes need patches with more elasticity.

Rubber cement vs. contact glue

Patch kits include a tiny tube of “rubber cement”. The instructions say to wait 3 min before applying the patch. That’s similar to contact glue instructions. The only difference is contact glue instructions direct us to glue BOTH surfaces then press them together a few min later, whereas the repair kits never say to put glue on the patch (why is that?).

Are the two glues chemically different? I ask because it may not make sense for me to buy another patch kit when I happen to have a very big tube of contact glue for shoe repair.