Author Topic: Periodni sistem elemenata i sve lepote prirodnih nauka  (Read 2372 times)

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lilit

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Some things you have to do yourself.

Meho Krljic

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #1 on: 01-12-2016, 22:29:37 »
Zaista, istorijski.  :-| :-|

Meho Krljic

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #2 on: 28-01-2017, 08:51:22 »
Inače, decenijska diskusija o tome da li vodonik može da se smatra metalom, odnosno da li može da formira kristalnu strukturu pod dovoljno velikim pritiskom, je razrešena: može.
 
Brzo podsećanje na osnovnoškolsku hemiju: vodonik spada u prvu grupu periodnog sistema gde su svi ostali članovi decidno metali, ne samo po našem, jelte, intuitivnom osećaju (dakle, čvrsti su i reflektivni) nego i po tome što na sobnoj temperaturi formiraju kristalne rešetke i vezuju se međusobno metalnim vezama. Vodonik sa svoje strane na sobnoj temperaturi sedi u gasovitom stanju i formira skromne molekule od dva atoma kao i na primer nama poznati elementi azot ili kiseonik koji decidno spadaju u nemetale tako da se i on vodi kao nemetal. Takođe, ima tu i drugih, nrdskijih momenata, kao što je da se metali lakše jonizuju (energija potrebna da vodonik izgubi elektron je dva i po puta viša od energije najviše plasiranog metala, litijuma), da vodonik formira kovalentne veze (kojima metali nisu skloni) kao i stabilna jedinjenja u kojima je vodonik u jonskoj formi (hidridi) a što nije karakteristično za metale. Ali od tridesetih se godina prošlog veka teoriše o tome da pod dovoljno visokim pritiskom vodonik može da formira kristalnu rešetku i problem je uvek bio napraviti alatku koja može dovoljno da ga pritisne da ga natera da se metalizuje pre nego što se sprava polomi. Konačno je to postignuto:
 
 An 80-year-old prediction may come true: Scientists turn hydrogen into a metal
 
A ovo potencijalno može da ima i vrlo praktične aplikacije, prvo jer je vodonik u metalnom stanju, naravno, superprovodnik, ali ako se postigne da ova struktura ostane stabilna i pod normalnim uslovima (kao što dijamant ostaje stabilan pod normalnim uslovima u svojoj kristalnoj rešetci iako je za njeno formiranje potreban ogroman pritisak) to bi imalo veliku primenu u elektrotehnici...
 
Detalji:
 
https://youtu.be/1qitm5fteL0
 
 
Naravno, dok se ovo ne pir rivjuuje i dok se ne ponovi na drugom mestu ne treba mnogo da se ložimo (videti ovaj tekst za skeptične kolege: http://www.sciencemag.org/news/2017/01/diamond-vise-turns-hydrogen-metal-potentially-ending-80-year-quest)

lilit

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #3 on: 28-01-2017, 10:47:17 »
kako je ovo lepo!

naravno, zamerke pirova deluju razumno pa moramo da čekamo da se odradi eksperiment bez limitations prisutnih ovde, al ako se pokaže da je moguće - nebo je granica.
Some things you have to do yourself.

Meho Krljic

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #4 on: 28-01-2017, 13:18:40 »
Za par decenija možda budemo imali potpuno revolucionisanu industriju superprovodnika, pravljenih od najobilnijeg materijala u vasioni!!!  :lol:

Meho Krljic

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #5 on: 30-01-2017, 09:33:35 »
Recimo da ovo isto ide na ovaj topik. Ipak, radi se o materiji koja je "u stalnom kretanju a bez potrošnje energije".  :shock: :shock: :shock:


Scientists have confirmed a brand new form of matter: time crystals


Meho Krljic

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #6 on: 05-03-2017, 08:25:09 »
Ne znam na koji topik bi ovo najpametnije išlo pa evo ovde, ipak se radi o prirodnim naukama u sudaru sa tehničkim a sve u nekoj genijalnoj pripremi za postvarenje onog što smo čitali u Johnny Mnemonic i milion drugih priča, romana itd.:
 
 Researchers store computer operating system and short movie on DNA
 
 
Quote
Humanity may soon generate more data than hard drives or magnetic tape can handle, a problem that has scientists turning to nature's age-old solution for information-storage—DNA.
In a new study in Science, a pair of researchers at Columbia University and the New York Genome Center (NYGC) show that an algorithm designed for streaming video on a cellphone can unlock DNA's nearly full storage potential by squeezing more information into its four base nucleotides. They demonstrate that this technology is also extremely reliable.
DNA is an ideal storage medium because it's ultra-compact and can last hundreds of thousands of years if kept in a cool, dry place, as demonstrated by the recent recovery of DNA from the bones of a 430,000-year-old human ancestor found in a cave in Spain.
"DNA won't degrade over time like cassette tapes and CDs, and it won't become obsolete—if it does, we have bigger problems," said study coauthor Yaniv Erlich, a computer science professor at Columbia Engineering, a member of Columbia's Data Science Institute, and a core member of the NYGC.
Erlich and his colleague Dina Zielinski, an associate scientist at NYGC, chose six files to encode, or write, into DNA: a full computer operating system, an 1895 French film, "Arrival of a train at La Ciotat," a $50 Amazon gift card, a computer virus, a Pioneer plaque and a 1948 study by information theorist Claude Shannon.
They compressed the files into a master file, and then split the data into short strings of binary code made up of ones and zeros. Using an erasure-correcting algorithm called fountain codes, they randomly packaged the strings into so-called droplets, and mapped the ones and zeros in each droplet to the four nucleotide bases in DNA: A, G, C and T. The algorithm deleted letter combinations known to create errors, and added a barcode to each droplet to help reassemble the files later.
In all, they generated a digital list of 72,000 DNA strands, each 200 bases long, and sent it in a text file to a San Francisco DNA-synthesis startup, Twist Bioscience, that specializes in turning digital data into biological data. Two weeks later, they received a vial holding a speck of DNA molecules.
To retrieve their files, they used modern sequencing technology to read the DNA strands, followed by software to translate the genetic code back into binary. They recovered their files with zero errors, the study reports. (In this short demo, Erlich opens his archived operating system on a virtual machine and plays a game of Minesweeper to celebrate.)
They also demonstrated that a virtually unlimited number of copies of the files could be created with their coding technique by multiplying their DNA sample through polymerase chain reaction (PCR), and that those copies, and even copies of their copies, and so on, could be recovered error-free.
Finally, the researchers show that their coding strategy packs 215 petabytes of data on a single gram of DNA—100 times more than methods published by pioneering researchers George Church at Harvard, and Nick Goldman and Ewan Birney at the European Bioinformatics Institute. "We believe this is the highest-density data-storage device ever created," said Erlich.
The capacity of DNA data-storage is theoretically limited to two binary digits for each nucleotide, but the biological constraints of DNA itself and the need to include redundant information to reassemble and read the fragments later reduces its capacity to 1.8 binary digits per nucleotide base.
The team's insight was to apply fountain codes, a technique Erlich remembered from graduate school, to make the reading and writing process more efficient. With their DNA Fountain technique, Erlich and Zielinski pack an average of 1.6 bits into each base nucleotide. That's at least 60 percent more data than previously published methods, and close to the 1.8-bit limit.
Cost still remains a barrier. The researchers spent $7,000 to synthesize the DNA they used to archive their 2 megabytes of data, and another $2,000 to read it. Though the price of DNA sequencing has fallen exponentially, there may not be the same demand for DNA synthesis, says Sri Kosuri, a biochemistry professor at UCLA who was not involved in the study. "Investors may not be willing to risk tons of money to bring costs down," he said.
But the price of DNA synthesis can be vastly reduced if lower-quality molecules are produced, and coding strategies like DNA Fountain are used to fix molecular errors, says Erlich. "We can do more of the heavy lifting on the computer to take the burden off time-intensive molecular coding," he said.
 
 

Meho Krljic

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #7 on: 06-03-2017, 08:53:34 »
Researchers create new form of matter—supersolid is crystalline and superfluid at the same time



Quote
MIT physicists have created a new form of matter, a supersolid, which combines the properties of solids with those of superfluids.

By using lasers to manipulate a superfluid gas known as a Bose-Einstein condensate, the team was able to coax the condensate into a quantum phase of matter that has a rigid structure—like a solid—and can flow without viscosity—a key characteristic of a superfluid. Studies into this apparently contradictory phase of matter could yield deeper insights into superfluids and superconductors, which are important for improvements in technologies such as superconducting magnets and sensors, as well as efficient energy transport. The researchers report their results this week in the journal Nature.

"It is counterintuitive to have a material which combines superfluidity and solidity," says team leader Wolfgang Ketterle, the John D. MacArthur Professor of Physics at MIT. "If your coffee was superfluid and you stirred it, it would continue to spin around forever."

Physicists had predicted the possibility of supersolids but had not observed them in the lab. They theorized that solid helium could become superfluid if helium atoms could move around in a solid crystal of helium, effectively becoming a supersolid. However, the experimental proof remained elusive.

The team used a combination of laser cooling and evaporative cooling methods, originally co-developed by Ketterle, to cool atoms of sodium to nanokelvin temperatures. Atoms of sodium are known as bosons, for their even number of nucleons and electrons. When cooled to near absolute zero, bosons form a superfluid state of dilute gas, called a Bose-Einstein condensate, or BEC.

Ketterle co-discovered BECs—a discovery for which he was recognized with the 2001 Nobel Prize in physics.

"The challenge was now to add something to the BEC to make sure it developed a shape or form beyond the shape of the 'atom trap,' which is the defining characteristic of a solid," explains Ketterle.

Flipping the spin, finding the stripes

To create the supersolid state, the team manipulated the motion of the atoms of the BEC using laser beams, introducing "spin-orbit coupling."

In their ultrahigh-vacuum chamber, the team used an initial set of lasers to convert half of the condensate's atoms to a different quantum state, or spin, essentially creating a mixture of two Bose-Einstein condensates. Additional laser beams then transferred atoms between the two condensates, called a "spin flip."

"These extra lasers gave the 'spin-flipped' atoms an extra kick to realize the spin-orbit coupling," Ketterle says.

Physicists had predicted that a spin-orbit coupled Bose-Einstein condensate would be a supersolid due to a spontaneous "density modulation." Like a crystalline solid, the density of a supersolid is no longer constant and instead has a ripple or wave-like pattern called the "stripe phase."

"The hardest part was to observe this density modulation," says Junru Li, an MIT graduate student who worked on the discovery. This observation was accomplished with another laser, the beam of which was diffracted by the density modulation. "The recipe for the supersolid is really simple," Li adds, "but it was a big challenge to precisely align all the laser beams and to get everything stable to observe the stripe phase."

Mapping out what is possible in nature

Currently, the supersolid only exists at extremely low temperatures under ultrahigh-vacuum conditions. Going forward, the team plans to carry out further experiments on supersolids and spin-orbit coupling, characterizing and understanding the properties of the new form of matter they created.

"With our cold atoms, we are mapping out what is possible in nature," explains Ketterle. "Now that we have experimentally proven that the theories predicting supersolids are correct, we hope to inspire further research, possibly with unanticipated results."

Several research groups were working on realizing the first supersolid. In the same issue of Nature, a group in Switzerland reported an alternative way of turning a Bose-Einstein condensate into a supersolid with the help of mirrors, which collected laser light scattering by the atoms. "The simultaneous realization by two groups shows how big the interest is in this new form of matter," says Ketterle.


Read more at: https://phys.org/news/2017-03-mattersupersolid-crystalline-superfluid.html#jCp

lilit

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #8 on: 16-11-2017, 00:08:42 »
sreća, rados’... kad stigne isporuka na suvom ledu :lol:


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Ugly MF

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #11 on: 12-12-2017, 08:58:56 »
The Coolest Scientific Discoveries of 2017

Iskreno se nadam da je taj tvoj Gizmodo neki fart-joke sajt....u protivnom,
jao si ga covecanstvu!




Meho Krljic

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #12 on: 12-12-2017, 09:03:34 »
Hahah, nije, on je deo Gawkerove mreže blogova. Mislim, nije neki OZBILJAN sajt koji se bavi tehnologijom ili naukom, ali nije humoristički, nego više, kao, blogujemo, al profesionalno.

Ugly MF

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #13 on: 12-12-2017, 09:11:20 »
Nemoj me zajebavas :)

'Nesto mi tu smrdi da nam neko uvaljuje neke cajpere,a?'


lilit

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #15 on: 13-02-2018, 09:21:35 »
ne smem ni da razmišljam o tome koliko bismo redukovali infection rate i sve ostalo da je čista pijaća voda, a i ona za umivanje, dostupna celoj planeti.
al ne vidim da ćemo tu stići u narednih 50 godina.
Some things you have to do yourself.

scallop

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #16 on: 13-02-2018, 09:37:15 »
Teo sam da napišem nešto na ovu temu, ali me je stra' da će Bata ili neko drugi da me demantuje.
Ipak se ne radi o zadovoljavanju svetskih potreba za pijaćom vodom nego o jeftinijem načinu zadovoljavanja potreba za litijumom, pa se može desiti da "roboti ne zaravne Kanarevo brdo". Dakle, za nas dobra i loša vest. Neću da ulazim u putovanje od laboratorijske do okeanske separacije litijuma. Mukotrpan je taj put, ali, biće vode i soli kao nuzproizvoda, a za baterije ne brinite.


Isti posao rade i pošumljeni obronci Atlasa, bez litijuma. No, podizanje planina je optimistička priča o održanju prirodnih resursa. Nju ćemo da ostavimo za teraformiranje Marsa. :)
Never argue with stupid people, they will drag you down to their level and then beat you with experience. - Mark Twain.

lilit

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #17 on: 22-02-2018, 18:41:21 »
Getting out of hot water: does mobile DNA help?
The first DNA analysis of an ammonia-oxidizing microbe gives clues to how its extremophilic ancestor moved from hot springs to conquer the world.

https://blog.frontiersin.org/2018/01/31/microbiology-extremophile-hot-spring-microbe-archeon/
Some things you have to do yourself.


lilit

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #19 on: 28-04-2018, 08:07:17 »
ovo je za topik: živimo SF. prelepo! i prekorisno! hvala.
znači, amejzing.
Some things you have to do yourself.

lilit

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #20 on: 05-10-2018, 06:20:30 »
nobel za hemiju 2018. prepolovljen, jedan deo otišao (opet!) imunologiji :lol:
Quote
The other half of this year’s Nobel Prize in Chemistry is shared by George P. Smith and Sir Gregory P. Winter. In 1985, George Smith developed an elegant method known as phage display, where a bacteriophage – a virus that infects bacteria – can be used to evolve new proteins. Gregory Winter used phage display for the directed evolution of antibodies, with the aim of producing new pharmaceuticals. The first one based on this method, adalimumab, was approved in 2002 and is used for rheumatoid arthritis, psoriasis and inflammatory bowel diseases. Since then, phage display has produced anti-bodies that can neutralise toxins, counteract autoimmune diseases and cure metastatic cancer.
https://www.nobelprize.org/prizes/chemistry/2018/press-release/
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Meho Krljic

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #21 on: 05-10-2018, 07:51:20 »
Ovako, na osnovu ovog kratkog sižea, deluje kao da je nagrada otišla u prave ruke.


lilit

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Re: Periodni sistem elemenata i sve lepote prirodnih nauka
« Reply #23 on: 19-11-2018, 20:27:55 »
“Little ogres”: A scientific discovery has unearthed a new kingdom of life

lepo, lepo, al nije peti kingdom već moguće novi supra-kingdom (5-8, zavisno koja scientific grupa klasifikuje).
svakako su u eukariotima, a stiglo krajnje vreme da se nomenklatura apdejtuje.
Some things you have to do yourself.