Wikipedia:Reference desk/Archives/Science/2018 September 18
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September 18 edit
Which charge is stronger, negative or positive? edit
Which of the charges (in chemistry, physics, electricity) is stronger, positive or negative? For example, if we have more negative than positive charge, the one that will be dominant is the negative or the positive charge cancels any negative charge? (I have the same question about having more positive than negative) 93.126.116.89 (talk) 05:19, 18 September 2018 (UTC)
- Neither. They're equal and opposite. Did something give you the impression that one was stronger? --47.146.63.87 (talk) 05:36, 18 September 2018 (UTC)
- To be more precise, a proton and electron have equal and opposite charges. However, it is possible for something to have more of one than another. For example, a hydrogen atom has one proton and one electron, giving it zero charge. If it loses its electron, it becomes a hydrogen ion with a +1 charge. A Chlorine atom can gain an extra electron, forming an ion with a -1 charge, while an oxygen atom can gain two extra electrons, giving it a -2 charge. (Chemical compounds form by combining positive and negative ions so that the charges balance out. That's why hydrogen chloride (HCL) has equal amounts of hydrogen and chlorine, but water (H2O) has twice as much hydrogen as oxygen). Iapetus (talk) 09:39, 18 September 2018 (UTC)
- For a more complex answer at a fundamental level, see C-symmetry. For most fundamental physical situations, particles obey C-symmetry, meaning that the laws of physics are identical for particles which have opposite charges (for this purpose, the opposite of a proton is an antiproton and not an electron; while the opposite of an electron is a positron (antielectron).) Not everything obeys C-symmetry, however. The lack of C-symmetry in the weak interaction led to the development of a more basic type of symmetry that is universal, known as CPT symmetry (charge-parity-time symmetry). --Jayron32 11:20, 18 September 2018 (UTC)
- To be more precise, a proton and electron have equal and opposite charges. However, it is possible for something to have more of one than another. For example, a hydrogen atom has one proton and one electron, giving it zero charge. If it loses its electron, it becomes a hydrogen ion with a +1 charge. A Chlorine atom can gain an extra electron, forming an ion with a -1 charge, while an oxygen atom can gain two extra electrons, giving it a -2 charge. (Chemical compounds form by combining positive and negative ions so that the charges balance out. That's why hydrogen chloride (HCL) has equal amounts of hydrogen and chlorine, but water (H2O) has twice as much hydrogen as oxygen). Iapetus (talk) 09:39, 18 September 2018 (UTC)
- The error is in assuming that the two types of charge are invariable. Bear in mind that quarks have electrical charges of +2⁄3e or −1⁄3e. Protons and electrons having opposite and equal charges has led to that being the unit of charge - but actual charge doesn't always have to be +1 or -1. Wymspen (talk) 10:16, 19 September 2018 (UTC)
- Charge is still quantized, though. Historically, we picked the wrong thing to call the "1", but the entire system works (for example) if we had picked the charge of the down quark and called that "1". It's still quantized, and there is still a fundamental charge which all other charges must be a multiple of. It's just not "1" in our current system. --Jayron32 11:13, 19 September 2018 (UTC)
- "Wrong" is subjective. Free quarks don't exist below the Hagedorn temperature, so outside of high-energy physics we only care about the charges on electrons, protons, and other "stable" particles. It's simpler to use "1" for this; otherwise we'd be doing a lot of base 3 math. --47.146.63.87 (talk) 08:16, 21 September 2018 (UTC)
- Charge is still quantized, though. Historically, we picked the wrong thing to call the "1", but the entire system works (for example) if we had picked the charge of the down quark and called that "1". It's still quantized, and there is still a fundamental charge which all other charges must be a multiple of. It's just not "1" in our current system. --Jayron32 11:13, 19 September 2018 (UTC)
Although the negative and positive charges are equal and opposite fundamentally, as per the above discussion, in chemistry, it's quite often the case that the negative charges of the electron cloud are felt more strongly than the positive charges of the nucleus. This is because the electrons are on the outside, so they form a shield around the nucleus. This is discussed under the subjects of electron shielding and effective nuclear charge. The latter article shows that for neutral atoms, increasing charge of the nucleus by one results in less than one additional charge being felt outside the electron cloud. Neon for example has 10 positive charges (and 10 negative charges) but a charge of only +5.758 is felt by the outermost electrons. Handschuh-talk to me 10:45, 22 September 2018 (UTC)
- Addendum: it's not just that electrons are on the outside, but that they exist in shells around the nucleus. This is because electrons are fermions, and therefore the Pauli exclusion principle keeps them from all occupying the same quantum state, which bosons are free to do. --47.146.63.87 (talk) 06:04, 23 September 2018 (UTC)
Have there been any predictions/projections on when we will be able to regrow human skin and thus completely eliminate white scars? edit
Have there been any predictions/projections on when we will be able to regrow human skin and thus completely eliminate white scars? Futurist110 (talk) 20:01, 18 September 2018 (UTC)
- Human skin does "regrow", but as scar tissue; there is research for "wounds to heal as regenerated skin rather than scar tissue":[1], but that doesn't cover already existing scars. 2606:A000:1126:4CA:0:98F2:CFF6:1782 (talk) 23:02, 18 September 2018 (UTC)
- Biology is funny. I remember a time when I was 16 or so and managed to somehow slice or rip open the skin across my Achilles tendon on a rock, seemingly all the way to the fascia. It didn't hurt, and didn't bleed, and I didn't want the bother of a doctor, so I just closed it up a little and left it under a bandage; it healed without trouble with a fairly wide white scar. Years later, I couldn't find the scar at all. But another scar from a burn on a finger from that time never went away, though after many cycles of becoming aggravated and being picked at its appearance reduced a bit. We have an articles scar free healing and decent reviews are available, but it seems like there is a lot of randomness in the process still in need of explanation. Wnt (talk) 00:05, 19 September 2018 (UTC)
- See [2]. 92.8.178.228 (talk) 10:41, 19 September 2018 (UTC)
- Biology is funny. I remember a time when I was 16 or so and managed to somehow slice or rip open the skin across my Achilles tendon on a rock, seemingly all the way to the fascia. It didn't hurt, and didn't bleed, and I didn't want the bother of a doctor, so I just closed it up a little and left it under a bandage; it healed without trouble with a fairly wide white scar. Years later, I couldn't find the scar at all. But another scar from a burn on a finger from that time never went away, though after many cycles of becoming aggravated and being picked at its appearance reduced a bit. We have an articles scar free healing and decent reviews are available, but it seems like there is a lot of randomness in the process still in need of explanation. Wnt (talk) 00:05, 19 September 2018 (UTC)
I found the manufacturer who mentions CTGF, and cites [3]. The design of the modified asymmetric siRNA is given in this appendix. The actual substance is therefore the annealed combination of
- cp - asiCTGF sense = mCUmUAmCCmGAmCUmGGmAA(s)mG(s)A(s)-chol
- cp - asiCTGF antisense = UCUUCCAGUCGGUAmAmGmCmCmGmCmGmAmGmGmGmCmA(s)mG(s)mG(s)mC(s)mC-chol
Where mN = 2’ - OMe modified nucleotide, (s) = phosphorothioate, and -chol = cholesterol.
If this holds up, it is not merely a medical advance, but also a big technical step forward in siRNA technology, with applications to a vast number of target genes. And, this should be a type of drug fairly readily manufactured on an illicit basis by those with the will to do so, making it potentially accessible to the common people. Wnt (talk) 13:56, 19 September 2018 (UTC)
- Would this also work for old white scars? Futurist110 (talk) 03:53, 20 September 2018 (UTC)
- We have an unconfirmed report from the manufacturer that it works on a fresh wound in a rat. Everything else is fun... but speculative at this point. Unless someone tries the experiment I won't even have a guess what would happen there; I'm not very optimistic but you can look up CTGF and related articles and see what you think. Wnt (talk) 13:50, 20 September 2018 (UTC)