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NIN
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icon Vijesti iz svijeta NAUKE!

Nestat e Los Angeles


Studija prema kojoj je ogromno razaranje juga Kalifornije gotovo neizbjeno nikako ne ide u prilog stanovnicima: em ostaju bez domova, em e osiguravajua drutva prije potresa dii premije na nekretnine.

Ameriko geoloko drutvo objavilo je prva dravna predvianja potresa za Kaliforniju i izgledi nisu dobri. Studija otkriva da postoji ak 99,7% vjerojatnosti da potres magnitude 6,7 ili jai pogodi Kaliforniju do 2037. godine, dok vjerojatnost potresa magnitude 7,5 ili vie iznosi 46%.

Trogodinju studiju naruio je Kalifornijski ured za potrese, javna agencija koju financiraju privatne tvrtke.Vjerojatnosti su proizale iz modela koji u obzir uzima empirijske podatke iz prethodnih potresa, najnovije fizikalne podatke iz raznih izvora te precizne satelitske podatke o pomicanju na povrini Zemlje. "To je najpotpunije predvianje potresa ikada izraeno za Kaliforniju", kae Tom Jordan, direktor Centra za potrese june Kalifornije.

Gomilanje energije

Studija je fokusirana na specifine brazde izmeu tektonskih ploa i urbana podruja, ali daje i predvianje za itavu regiju. Tako bi stanovnici june Kalifornije trebali biti mrvicu zabrinutiji jer vjerojatnost potresa magnitude od najmanje 7,5 prije 2037. godine iznosi 37% za jug, dok za sjever Kalifornije iznosi 15%. To je djelomino i zato jer na jugu u posljednje vrijeme nije bilo seizmoloke aktivnosti, pa znanstvenici zakljuuju da tom podruju slijedi vrlo razorni potres.

Potres poput onog koji je pogodio San Francisco 1906. godine na jugu se nije dogodio od 1857. Juna polovica od 1300 kilometara dugake Brazde San Andreas prolazi kroz junu Kaliforniju, a tu nije zabiljeena razorna seizmoloka aktivnost od 1680. godine. Predvianje iz iste studije govori kako postoji 67% ansi da potres magnitude 6,7 pogodi Los Angeles prije 2037. godine, dok za podruje San Francisca ona iznosi 63%.

"U tim brazdama se itavo vrijeme akumulira ogromna energija, to razorni potres ini vrlo vjerojatnim", rekao je Jordan.

net.hr

Pozdrav

[Edited by NIN on 17-04-2008 at 01:51 GMT]

17-04-2008 at 01:50 | Ukljui u odgovor
NIN
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Smreke od osam tisua godina


Znanstvenici su visoko u planinama zapadne vedske otkrili skupinu izdrljivih norvekih smreka, koje su stare osam tisua godina i time vjerojatno najstarija stabla na svijetu.

Izdrljive smreke (Picea abies) otkrivene su na lokaciji na kojoj je zatiena od novijih opasnosti poput sjee stabala, ali izloena nepovoljnim vremenskim uvjetima gorja koje dijeli vedsku od Norveke.

"Testiranje u laboratoriju u Miamiju na Floridi pokazalo je da su najstarija meu stablima pustila korijenje prije pet, est i osam tisua godina i moe ih se smatrati najstarijim ivim stablima", rekao je profesor sveuilita u Umei Leif Kullman. Tisuljetni bor nazvan Metuzalem u Kaliforniji i dalje je s 4733 godina najstarije pojedinano stablo na svijetu. Druge dvije skupine smreka, takoer pronaene za istraivanja klimatskih promjena u vedskome okrugu Dalarni, stare su od 4000 do 5500 godina.

"To su bile prve ume nakon ledenoga doba", kae Lars Hedlund, voditelj ekolokih istraivanja u Dalarni i suradnik u studiji o klimatskim promjenama.

"Neprestano se mijenja ono to raste izdan tla, ali genetski su ta stabla identina onima kakva su rasla prije mnogo tisua godina", rekao je .

"Iako stablo s jednim deblom ne moe izdrati due od 600 godina, smreke su se odrale jer je raslo novo deblo im bi staro uvenulo", kae profesor Kullman.

Hina|Net.hr

17-04-2008 at 01:54 | Ukljui u odgovor
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Ludwik Leibler, ef odjela za kemiju Francuskog nacionalnog centra za znanstvena istraivanja (CNRS) i voditelj istraivakog odjela kole ESPCI, prikazuje tenzijski pokus samoobnavljajue supramolekularne gume koju su stvorili kemiari CNRS-a i privatne tvrtke Arkema. Prema tekstu objavljenom u britanskom magazinu Nature, molekularna smjesa za koju drugi znanstvenici kau da ima neko magino svojstvo moe se na sobnoj temperaturi sama obnoviti za 15 minuta jednostavnim spajanjem odlomljenih dijelova

Foto: AFP

17-04-2008 at 03:33 | Ukljui u odgovor
Neidhardt
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icon Re: Re: Vijesti iz svijeta NAUKE!

citat:
NIN wrote:


Ludwik Leibler, ef odjela za kemiju Francuskog nacionalnog centra za znanstvena istraivanja (CNRS) i voditelj istraivakog odjela kole ESPCI, prikazuje tenzijski pokus samoobnavljajue supramolekularne gume koju su stvorili kemiari CNRS-a i privatne tvrtke Arkema. Prema tekstu objavljenom u britanskom magazinu Nature, molekularna smjesa za koju drugi znanstvenici kau da ima neko magino svojstvo moe se na sobnoj temperaturi sama obnoviti za 15 minuta jednostavnim spajanjem odlomljenih dijelova

Foto: AFP


NIN, imas li vise o ovome?
21-04-2008 at 14:51 | Ukljui u odgovor
NIN
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citat:
Neidhardt wrote:
NIN, imas li vise o ovome?


Kako da ne druze moj!

Supra-molecular chemistry yields new materials with outstanding properties

Broken or cracked rubber that can self-heal simply through new contact, ultra-tough bitumen laid at 140C instead of 180C, easily-molded plastics with superior mechanical strength and chemical stability, and hotmelt glues from vegetable origin all have one thing in common: they are based on the concept of supramolecular chemistry, a promising branch of chemistry that offers a major improvement potential for everyday applications. Arkema, a partner in this research, is one of the first manufacturers poised to offer products derived from this chemistry in the near future.


A paper to be published on February 21st in the magazine Nature entitled Self-healing and thermoreversible rubber from supramolecular assembly reports on the discovery of a new rubber which features the unique property of being self-repairing or self-healing . This material is the fruit of research work conducted in the Matière Molle et Chimie Laboratory, a mixed research unit between CNRS and ESPCI (Ecole Suprieure de Physique et de Chimie Industrielles) run by Professor Ludwik Leibler, a former colleague of Pierre Gilles de Gennes, 1991 Physics Nobel Prize. Today, Arkema, as a key industrial partner in this research, in particular through its expertise in nanostructured materials, is entering the phase of commercial development for several materials derived from this research.



From traditional molecular chemistry to supramolecular chemistry


For over two centuries traditional molecular chemistry has focused on transforming matter by creating permanent bonds linking up atoms within molecules. Polymer chemistry, derived from this traditional chemistry, has developed considerably in the last century, the objective being to produce large molecular chains that combine sturdiness with light weight.



Supramolecular chemistry a scientific field that has come to the fore in recent years in particular thanks to the Chemistry Nobel Prize presented to Jean-Marie Lehn, Donald Cram and Charles Pedersen in 1987 consists in building complex assemblies of molecules joined by non-permanent or reversible bonds; these assemblies of molecules with a reversible structure are called supramolecular . The same assembly principles can by and large be observed in biological systems (e.g. DNA). It is precisely the application of these concepts with the ultimate aim of developing materials with innovative properties that the Matière Molle et Chimie Laboratory has been focusing on since 2000. Over the last few years, the Laboratory has developed various supramolecular materials from molecules of different nature (small molecules derived from vegetable oils, large molecular chains in existing polymers) by creating hydrogen bonds between these molecules whose particularity, unlike conventional chemical bonds, is to be reversible under the effect of temperature.



Supramolecular chemistry: from concept to everyday applications


This new approach to the chemistry of materials is opening up the way to wide-ranging innovations and developments.



Materials can indeed be developed from small molecules derived from vegetable oils, and be processed or applied at low temperature, with a behavior in the solid state that is typical of a polymer with large molecular chains, e.g. sturdiness and strength. Another typical application is the example of an existing conventional polymer which is modified by integrating these temporary bonds, and so will be able to combine excellent fluidity at processing temperature with outstanding properties in the solid state, which are identical to, if not better than, those of an existing non-modified polymer. Yet another highly promising application can already be envisaged for bitumens laid on high-traffic carriageways: these specialty bitumens are modified with polymers which make them more hard-wearing, albeit to the detriment of their viscosity; they then have to be heated at high temperature (180C) for a long period of time for their preparation and application, which are highly energy-intensive operations. By adding to the bitumen an additive of vegetable origin derived from supramolecular chemistry, it is possible to lower to 140C the temperature needed to heat up these bitumens prior to application while keeping their mechanical strength, and facilitate their recycling.

http://www.arkema.com/sites/group/en/press/pr_detail.page?p_filepath=/templatedata/Content/Press_Release/
data/en/2008/080221_supra_molecular_chemistry_yields_new_materials_with_outstanding_properties.xml

http://www2.cnrs.fr/en/1124.htm

Pozdrav...


[Edited by NIN on 21-04-2008 at 15:22 GMT]
21-04-2008 at 15:19 | Ukljui u odgovor
NIN
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citat:
Neidhardt wrote:
NIN, imas li vise o ovome?


Drug, evo imas nesto detaljnije i ovdje, mada jeste da je malo strucnije al da se rastabirit...

http://eprints.whiterose.ac.uk/107/1/ungarg1.pdf

Pozdrav...
21-04-2008 at 15:33 | Ukljui u odgovor
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icon Re: Vijesti iz svijeta NAUKE!

Klonirani psi e otkrivati drogu


Carinici u Junoj Koreji su pokazali leglo zlatnih retrivera koji prolaze viemjesenu obuku nakon to su klonirani iz stanica psa koji se ve bavio tim policijskim poslom.

Juna Koreja planira klonirane pse koristiti za otkrivanje droge i eksploziva. Ako prou trening u slubu bi mogli ui idue godine, kau dunosnici.

Kloniranje su izveli strunjaci sa Nacionalnog sveuilita koji su 2005. godine klonirali prvog psa, afganistanskog hrta Snuppya.

Znanstveni tim vodio je Lee Byeong-chun, najblii suradnik osramoenog znanstvenika Hwanga Woo-suka. Njegova velika otkria na podruju matinih stanica pokazala su se lanima, dok je kloniranje pasa znanstveno potvreno.

26-04-2008 at 08:17 | Ukljui u odgovor
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Ancient Maya Tomb Yields "Amazing" Fabrics

Ker Than
for National Geographic News

April 25, 2008
Fabric fragments excavated from the tomb of an ancient Maya queen rival modern textiles in their complexity and quality, scientists say.

The tomb was discovered in the Maya city of Copn in Honduras by a team led by archaeologist Robert Sharer of the University of Pennsylvania.



Researchers believe the queen, whose name is not known, was buried in the fifth century A.D.

Some of the fabrics found within her tomb have thread counts of over 80 weft yarns per inch, said Margaret Ordonez, a textile expert at the University of Rhode Island who studied the cloth.

"This is in the range of the clothing that we wear," she said. "This is a higher thread count than your jeans."

Some of the fragments contained as many as 25 layers of fabric, stacked atop one another and fused together over time.

"Whats surprising is the fragments still exist," Ordonez said.

"Were talking about a humid climate, and to have fragments of fabric exist in the tomb for that long is just amazing."

Archaeologists suspect that the tomb was opened after the queens death to allow worshipers to perform rituals and make offerings of fabric and other items.

"It was fairly common that there was a ritual conducted, especially for royalty," Sharer, the archaeologist, said.

Ostatak teksta:
http://news.nationalgeographic.com/news/2008/04/080425-maya-fabric.html

Pozdrav...

26-04-2008 at 08:21 | Ukljui u odgovor
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Shape-shifting robots take form

How would you like to have your very own shape-shifter? Perhaps a liquid metal T-1000 Terminator to help around the house. Or a universal tool kit that could reshape itself into any implement at the press of a button. For an astronaut in orbit, an army mechanic in remote terrain or even a homeowner trying to fix a furnace on a cold winter night, it could be just the thing.

Well, one day maybe. The traditional approach to building shape-shifting devices has been to use materials based on shape memory alloys, polymer sheets or nanoparticles. But these have proved difficult to control and have other limitations, so researchers have begun taking a different and less exotic tack.

Their approach is known as self-reconfigurable robotics, and it takes advantage of recent advances in robot hardware, communications and control ...

http://technology.newscientist.com/channel/tech/mg19826531.200-shapeshifting-robots-take-form.html?DCMP=ILC-hmts&nsref=top1_pic

Pozdrav...

28-04-2008 at 11:57 | Ukljui u odgovor
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Bush cenzurira znanstvenike



Istraivanje provedeno u amerikoj Agenciji za zatitu okolia pokazuje da se politika esto uplie u njihov rad. Pogotovo usude li se znanstvenici nainjati neugodnu temu klimatskih promjena.

Anketa Sindikata zabrinutih znanstvenika, lobistike grupa sa sjeditem u Washingtonu, otkrila je da se mnogi od 1583 znanstvenika zaposlenih u agenciji boje otvoreno govoriti zbog straha od osvete upravnog osoblja koje im je nametnula Busheva administracija.

Vie od polovice meu njima izjavilo je kako nisu smjeli otvoreno razgovarati s medijima, a etvrtina ih kae da nisu smjeli objaviti znanstvene radove koji nisu "na liniji" agencije.

Tako se na istraivae esto vri pritisak da ne objavljuju rasprave povezane s klimatskim promjenama, kao to je erozija obale povezana s globalnim zatopljenjem i rastom razine mora.

EPA se nije slubeno oitovala o rezultatima ankete, koja je ipak uspjela izboriti malu pobjedu za slobodu govora.

Kad je jednom istraivau zabranjeno obraanje na konferenciji o klimatskim promjenama, organizatori su rekli da e umjesto zabranjenog govora odrati 20 minuta tiine pa je agencija naglo promijenila vlastitu odluku.

Net.hr

08-05-2008 at 06:59 | Ukljui u odgovor
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