Degradation Definition and 29 Threads

I started fostering kittens during the pandemic. A very useful veterinary disinfectant that I make use of is accelerated hydrogen peroxide. It is sold under the brand name "Rescue". In its concentrated form it has a shelf life of about 2 years. It's kind of expensive. Typically a dilution of a...

It seems that there is some problem with the paint on new Airbus A350s. The paint degrades, and the airlines think that the structural composites under the paint are degrading also. The problem could be structural airworthiness related, not just cosmetic. Qatar has grounded their fleet of...

I have been searching on Google about UV degradation of plastics , polypropylene in particular. I understand fully that it will break the plastics and so many plastics / polypropylene are not suitable for usage under sunlight. I also found that on the molecular level the sunlight will break the...

Hi! I recently noticed that posted images can lose quality when they are copied from a thread to a new thread. It seems they undergo some extra compression, and I don't understand why. Compare for instance the photos in this PF photo contest thread with the photos in the corresponding vote...

Hi there, it is commonly accepted that the lifespan of crystalline silicon solar cells is about 20-30years. And they define the lifespan as when the solar cells efficiency drop to about lower than 10%. However, what are the possible reasons for the degradation? I can only find research papers...

As the major contribution to degradation is due to the oxidation of oil which adds more polar constituents to the oil and thus increase the effective dielectric constant of the mixture.Can we assess the oil degradation just by looking at the effective dielectric constant changes over time? TIA

Urochrome/urobilin (structure below) is a tetrapyrrole, with the pyrroles connected with methylene (ish) bridges. I'm wondering if there's a good way to "crack" this molecule (like a hydrocarbon) along the bridges to yield the individual pyrroles. I ask because pyrrole synthesis is involved, and...

Good afternoon, I'm trying to search only based on bibliography or numerical and theoretical calculations the change of the thermal optical properties, namely the solar absorptivity, of a polyimide-based plastics (VESPEL SP-1) in space conditions (considering radiation, atomized oxygen atoms...

Is anyone familiar with a way to determine the half-life of a protein from its melt temperature (Tm)? It seems like there ought to be some sort of correlation, be it theoretical or empirical.

Hopefully I can get away with not describing the mechanics of the process. In general, if there is degradation of a solution via oxidisation, the process is not always purely oxidising, there can be other factors at work i.e. degradation may cause the solution to become hydrophobic and change...

Hello everyone obviously smarter than I. There is an answer I seek, to a project that is willing to be done. I'm considering manufacturing a piece of fitness strengthening equipment that is somewhat unique. There is some sort of equation I'm missing to have an understanding of how to go about...

This is probably a simple question, but here is a little background from which to view the problem. A cellphone tower transmits a 4G data signal at 700Mhz to my smartphone. Assuming that it does reach my phone does the wavelength of that databurst change in transit? Thanks.

Hi guys! I was wondering something about magnetic energy and well, I stumbled on to this. If there was a way to use a magnetic field's energy without influencing the actual magnet, would the degradation of the field increase at a faster rate?

People always wash their fiberglass boats, the part above water obviously. I was thinking if there is really a need for it? What is suitable to degradation, the plastic matrix, or the fibers of glass? And how does salt water promotes that degradation? Thank you Regards

Hi everybody, I'm involved with a project that wants to use PVC pipes as gutters for a rainwater harvesting system. The water is intended for human consumption (after it passes through clay filters to take care of biological contaminants). I've been looking at PVC degradation under UV and...

http://img850.imageshack.us/img850/1073/39228673.png In terms of drug shelf life, what might those compounds degrade into over time? For compound 1, that the azole rings CH3 group as well as the carbons attached to the sulfur could undergo autooxidation to alcohols. I can also see that...

A platinum aperture from a transmission electron microscope exhibits atomic variations after prolonged exposure to electromagnetic radiation. A gold aperture on the other hand does not. Using a backscatter electron detector we can observe sturctural features of materials below the surface...

I am trying to find the Absorbed dose for Silicon cells on a geostationary satellite from a period of (1996 to 2005) The Equation I have is: D(rad) = 1.68e-8 *((1/ρ)*dE/dx) * Phi Where: D is absorbed dose and units are (100 ergs/g or 0.01 J/Kg) (1/ρ)*dE/dx = (MeV*cm^2)/g...

hi, since light is energy moving through the fabric of space time at velocity c , it should lose energy due to gravitational waves. doesn't this mean that the light from a distant galaxy would keep decreasing in frequency? further more this would imply that light that was originally emitted as...

I have a bunch of rare Earth magnets that I bought a few years ago. For the most part, they've been rather haphazardly stored in a jumbled mess, with a few others stuck on the refrigerator. Today I noticed that at least some of them are noticeably weaker (particularly noticeable with the...

In a discussion I had recently, a topic was raised concerning some polymer degradation. Under high heat flow conditions and an oxygen environment, what is the plausibility of a cross-linked polydimethylsiloxane polymer degrading into hexamethylcyclotrisiloxane? I believe it is unlikely, and a...

Homework Statement I have to calculate the induced current in a coil a known distance from a solenoid (the secondary coil is on the axis of the solenoid). As the magnetic flux from the solenoid weakens with distance, I have applied biort-savart law to determine the stength of the magnetic...

Is it possible to calculate the surface degradation of a pipeline that water is flowing through it using FEA?

Maneuvering a spaceship using just Newtonian equations is a bit much for the average gamer. Therefore, most space-based first-person games use some form of "semi-Newtonian" motion. For example, reducing velocity by Velocity * 0.X per T = 1. So, using my limited math to factor that: Normal...

Hi guys, i was given a project based on the above topic and i know very little on it. Can anyone help to explain what's the difference between MSE and therotical MSE. Taylor series estimation and the modified taylor series. Thanks

Hi there, does anyone know which type of UV radiation would be most effective in polymer degradation or more importantly jet ink fading. Personally I think it should be UVC as it has the highest energy per photon but I could't find much about it so please help, it's very important as I'm behind...

Hi all, Long time lurker, very seldom poster. I have a need for an aqueous soluble compound that will thermally decompose or oxidize to form acidic products in the temperature range 100-300 C. It's well known that, on the other end of the scale, urea is water-soluble and near-neutral pH at...

I'm looking at a (uni) past paper and it has one of those typical Qs - a molecular weight determination has shown that an unknown peptide E is a pentapeptide and that it contains the amino acids glycine, tryptophan, proline, valine and alanine. Treatment of pentapeptide E with carboxypeptidase...

I don't know if this is the appropriate forum for this topic, but I've at least found some controversy surrounding the subject on the internet. The Earth is as far as I know basically a closed system for matter, with the exception of a few meteorites falling to the Earth and some rockets...