Sentences with phrase «on hydrogen bonds»
They may also help nanotechnologists design more advanced self - assembling materials, many of which rely heavily on hydrogen bonds to put themselves together correctly.
https://www.scientificamerican.com/ Not exact matches
Methane — a compound made up of one carbon atom bonded to four of hydrogen — is, according to the Intergovernmental Panel on Climate Change, 25 times as potent as carbon dioxide.
Their composition is largely dependent on hydrogen atoms in the molecules, and the ability of these to create hydrogen bonds with other elements.
They are also all saturated fats, chains of single - bonded carbon atoms with hydrogen atoms neatly lined up on either side of each carbon.
But when the music stops, the hydrogens go back to bind again to the carbons, and they don't always come down in the same positions on the remaining double bonds.
Another major advantage the catalysts have is that, while they are general in what substrate they can oxidize, they are very specific about which carbon - hydrogen bonds they cut — so much so that they target a certain spot on amino acids like proline, leucine or valine even when they are part of a much larger peptide chain.
Dr Russo said: «With this procedure, we have found that what makes water behave anomalously is the presence of a particular arrangement of the water's molecules, such as the tetrahedral arrangement, where a water molecule is hydrogen - bonded to four molecules located on the vertices of a tetrahedron.
White's group is working on catalysts that can modify a wider range of amino acids, particularly those with electron - rich aromatic functionality, which compete with the carbon - hydrogen bonds for oxidation using the current catalyst.
Weaker hydrogen bonds enable the ring in the structure on the right to spin up to a million times faster than in the structure on the left.
In aqueous fluids, amino acid residues that have polar sidechains — components that can have a charge under certain physiological conditions or that participate in hydrogen bonding — tend to be located on the surface of the protein where they can interact with water, which has negatively and positively side charges to its molecule.
You report on the redefinition by the International Union of Pure and Applied Chemistry (IUPAC) of hydrogen bond participants to...
On the atomic level, the layers are joined together by hydrogen bonds.
He has spent his career focused on just one bond, a link between a carbon and a hydrogen atom in a molecule of methane, the main component of natural gas.
«That's what his advance is pointing towards,» he says, «finding an alternative catalyst that will allow us to do oxygen evolution (breaking the bonds of water or H2O and forming oxygen) in concert with hydrogen» on a grand scale.
It seems likely that the highly localised heating on the surface of nanoparticles somehow disrupts hydrogen bonding within the ethanol — water mixture, allowing greater separation of ethanol from water molecules at higher concentrations of ethanol.
Of the two types of atom, oxygen has more pull on the electrons that they share to form the bonds between them, so the oxygen becomes slightly negatively charged and the hydrogens slightly positive.
Relying on a technique called infrared spectroscopy to explore the bonds between atoms, the researchers noticed it attaching to positive hydrogen atoms.
On page 761 of this issue, Banik et al. (4) describe an inventive catalytic approach that combines hydrogen - bond donors and Lewis acids to generate enhanced catalytic species able to effect new types of enantioselective reactions.
Also, the pressure exerted on the water is so high that hydrogen bond interactions with the graphene surface are overcome by the attractive van der Waals atomic interaction that draws together the graphene planes.
Such interactions are dependent on chemical bonds between hydrogen atoms.
Melanie Sanford, a chemist the University of Michigan, Ann Arbor, who focuses on using metal - based agents, primarily palladium, to catalyze reactions that substitute hydrogen in carbon - hydrogen bonds with other atoms or functional groups.
This type of olefin production method is based on dehydrogenation, that is the removal of hydrogens which leads to the creation of the C = C bond, the mark of olefins.
These are simulated crystal structures of virgin - DEB and T4H - DEB (chemically known as 1,4 - distyrylbenzene, a trans - isomer of DEB intermediate product after the capture of first 4 atomic hydrogen with 2 CH bonds on opposing sides of the carbon chain).
The researchers compared the effect of two different substrates on the growth of the phosphorene nanoflake — a copper substrate, commonly used for growing graphene, which bonds with the phosphorene through strong chemical processes, and a hexagonal hydrogen boron nitride (h - BN) substrate that couples with the phosphorene via weak van der Waals bonds.
Depending on how the carbon - hydrogen bonds are arranged and how many there are in the intermediate DEB products, the molecules can either attract or repel one another, and thus be less or more volatile, respectively.
IBS scientists used a reaction based on lithium dissolved in ammonia, called the «Birch - type reaction,» to introduce hydrogen onto graphene through the formation of C - H bonds.
«Melanie Sanford's insightful studies on the details as well as applications in the field of carbon - hydrogen bond activation have led to new methods to efficiently modify existing pharmaceuticals to arrive at new and better forms in a more efficient and rapid way than was previously possible.
Whereas the first is explained by H - bond with the proteins, the retarded hydrogen bond dynamics around hydrophobic residues is at first glance surprising and can be explained by the additional imposed steric constraints on the water molecules at hydrophobic sites.
P1 behavior was first investigated by STM at the liquid / solid interface: as an exemple, an arrangement of the molecules on HOPG presenting a quasi-square lattice (a = 2.1 nm, b = 2.2 nm, α = 94 °) self - assembled by hydrogen bonds between the pyridine unit and the methyl groups borne by the p - xylene core will be described, indicating strong intermolecular interactions between the molecules P1 leading to a supramolecular self - assembly independent of the underlying HOPG structure.
The results suggested that the tertiary amine groups bind to D97 on TM2 and E32 in the amino terminus of CXCR4 through hydrogen bonds while aromatic residues Y45, W94, H113 and Y255 establish hydrophobic interactions with the aromatic counterpart of identified compounds.
Thus, we designed and synthesized new molecular architectures based on the 3D Janus tecton concept, suitable for self - assembly on surface by supramolecular interactions such as coordination, halogen bond or hydrogen bond.3 Here we present two different model pyridyl end - capped molecules: the pedestal P1, and the naked pillar NP pedestal incorporating a cyclophane core.
For example, on the rhodium catalysts, the team's calculations showed that the carbon - carbon and carbon - hydrogen bond scissions are competitive, regardless of the rhodium particle size.
In the most common motif, created about 57 % of the time, hydroxide's oxygen atoms bonded with the hydrogen atoms on 4 water molecules while the hydroxide's hydrogen bonded to the oxygen atom on another water molecule.
Wiedner and Bullock focused on a cobalt catalyst and how it forms bonds with hydrogen atoms and shuffles electrons.
Hydrogen - bond acidic polymers are most widely used on acoustic wave sensors, which use sound waves in quartz chips to detect the vapors that are absorbed by the polymer.
A lot of the properties of water rely on creating and breaking these hydrogen bonds and a certain rate, time and energy.
We report on the use of the hydrogen bond acceptor properties of some phosphorus - containing functional groups for the assembly of a series of [2] rotaxanes.
These properties allow a spatial resolution on the sub-molecular scale allowing to visualize the bonding structure of a hydrogen bonded molecular network.
Integral to the polymer's design are electron - withdrawing fluorine atoms that create sites on the polymer with more positive hydrogen atoms leading to stronger hydrogen - bonding interactions and more sensitive sensors.
In the article, Grate reviews the motivation and principles behind the use of hydrogen - bond acidic polymers, covering the period from their first uses on chemical sensors in 1986 to early 2007.
Antiparallel beta - sheet structure of the enzyme catalase: The antiparallel hydrogen bonds (dotted) are between peptide NH and CO groups on adjacent strands.
Why it matters: At high pressures and low temperatures, like those found in permafrost or on the ocean's floor, water molecules organize into complex hydrate lattices that are held together by hydrogen bonds.
His current research is mainly focused on the application of efficient computational methods to understand the structure and dynamics of hydrogen - bonded systems ranging from water clusters to atmospheric aerosols.
His books on crystal engineering (Elsevier, 1989) and the weak hydrogen bond in structural chemistry and biology (OUP, 1999) are particularly well known.
The enzyme, Tang's team reports, resembles the video - game character «Pac - Man,» with two bowl - shaped halves joined by a hinge at one end and held closed, most of the time, by a latch of hydrogen bonds on the other end.
In nature, the polyunsaturated fatty acids are usually found in the cis form, which means that both hydrogen atoms at the double bond are on the same side.
I wonder if the described mechanism — CO2 making a hydrogen bond at a surface, then flipping along a fracture plane penetrating deeper into a crystalline material — also works on calcite and aragonite?