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| Â | Physics Today December 2004 - Articles: The Hydrogen Economy |
 | | Hydrogen can be adsorbed in molecular or atomic form on suitable surfaces, using pressure, temperature, or electrochemical potential to control its surface structure and bonding strength. | | | Hydrogen is abundant and generously distributed throughout the world without regard for national boundaries; using it to create a hydrogen economy—a future energy system based on hydrogen and electricity—only requires technology, not political access. | | | Hydrogen can be converted to electricity in fuel cells, but the production cost of prototype fuel cells remains high: $3000 per kilowatt of power produced for prototype fuel cells (mass production could reduce this cost by a factor of 10 or more), compared with $30 per kilowatt for gasoline engines. |
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http://www.physicstoday.org/vol-57/iss-12/p39.html
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|  | Supercritical Fluids – Fundamentals and Applications |
| | Understanding of hydrogen bonding among mixtures in supercritical fluids is important because of the increased interest in supercritical water solutions, and in polar cosolvents for supercritical fluid carbon dioxide. | | | An understanding of the phase behavior is important since the phase behavior observed in supercritical fluids considerably differ from the behavior observed in liquids. | | | However, several other supercritical fluids can be used, but the final choice would depend on the specific application and additional factors such as safety, flammability, phase behavior and solubility at the operating conditions and the cost of the fluid. |
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http://chemeng.iisc.ernet.in/giridhar/rect.html
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| Â | Troubleshooting Protein Binding in Nitrocellulose Membranes (Part 1)—Principles (IVDT archive, Mar 99) |
| | It is known that a number of forces are at work—specifically, hydrophobic interactions, hydrogen bonding, and electrostatic interactions—but a clear understanding of the exact effect and significance of each force has remained elusive. | | | This article offers further aid to product developers, discussing the basic principles involved in applying protein capture lines to nitrocellulose membranes, and highlighting some of the common problems that can be encountered during the development of an immunochromatographic assay. | | | Such an omission is often due to the fact that the latter elements are frequently considered set even before the beginning of the development process, leaving little opportunity for changes to be made. |
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http://www.devicelink.com/ivdt/archive/99/03/009.html
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| Â | Carboxylic.htm |
| | In earlier work, we have used Fourier transform infrared (FTIR) spectroscopy and a modified lattice-fluid hydrogen bonding (MLFHB) model to examine the effect of solvent density and solvation in formic acid association in both supercritical (SC) CO2 and C2H6. | | | On a more fundamental science front, formic acid and SCFAs represent an interesting series of molecules that provide the opportunity to study and correlate molecular structure with the tendency for these molecules to self-associate. | | | The influence of solvents on the equilibrium constant of dimer formation of some carboxylic acid compounds has been investigated by several research groups. |
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http://www.eng.auburn.edu/department/che/roberts/Carboxylic.htm
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| Â | Mineralogy Notes 3 |
| | If hydrogen bonds to a highly electronegative element such as F or O, its single electron will be confined to an orbital of the F or O leaving the proton exposed. | | | Ionic bonding is dominant in the non-opaque minerals and involves a complete transfer of electron(s) from cation to anion. | | | Two examples of elements that form this type of bonding are Au and Fe. |
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http://ruby.colorado.edu/~smyth/G30103.html
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| Â | UT-Austin Supercritical Fluids Group |
| | Panayiotou, C. and Sanchez, I.C.; 'Hydrogen Bonding in Fluids: An Equation-of-State Approach', J. Phys. | | | Given the lack of measurements of molecular interactions in supercritical water, due to significant experimental challenges at these severe conditions, computer simulation is an especially important tool. | | | The LFHB model also shows that specific interactions between CO2 and basic groups on polymers can be responsible for marked increases in CO2 sorption when compared to polymers with no specific interaction sites. |
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http://www.che.utexas.edu/supercritical/scfgroup.html
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| Â | Lithium(Li) |
| | Important compounds of lithium include the hydroxide, used for bonding carbon dioxide in the ventilator systems of spacecraft and submarines; and the hydride, used to inflate lifeboats, and its heavy hydrogen (deuterium) equivalent, used in making the hydrogen bomb. | | | Lithium carbonate, a common mineral, is used in the treatment of manic-depressive psychosis. |
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http://www.sof.edu/gallery/Christie/AhmadCo/lithium.html
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| Â | Laser device with wavelength converter using organic ionic crystal - US Patent 5381429 |
| | The nonlinear optical material is formed by removing water of crystallization from an organic ionic crystal containing at least one of aromatic ring and metal ion, and recrystallizing with a solvent comprising at least one of ionic bonding deuterium, hydrogen bonding deuterium, and heavy water. | | | In the organic ionic crystal, there are hydrogen atoms covalently bonded directly with carbon atoms, aside from ionic bonding hydrogen, hydrogen bonding hydrogen, and hydrogen of water of crystallization. | | | The nonlinear optical material is an organic ionic crystal containing at least one of aromatic ring and metal ion, showing second order nonlinear optical effect, being a material having at least one of ionic bonding hydrogen, hydrogen bonding hydrogen or hydrogen of water of crystallization replaced with deuterium. |
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http://www.patentstorm.us/patents/5381429.html
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| Â | Ch. 112, TEKS for Science. High School Chemistry. |
| | Chemistry Bonding Images - R. Hemphill: provides a visual image of the electron density models for period 2 atoms combining with hydrogen, the nonpolar bonding in hydrogen and chlorine molecules, the effect of bonding across period 3, electron density for the hydrogen halide series, and the electron density as methane becomes substituted with chlorine. | | | Shapes and Polarity of Covalent Molecules addresses the shapes of covalent molecules, molecular dipoles, the behavior of polar molecules, hydrogen bonding, and water. | | | Electron Configuration/Bonding - Southern Illinois University: addresses the electron configuration of the noble gases, ionic bonding, the properties of ionic compounds, the factors involved in the transfer of electrons, covalent bonding, electronegativity, electron dot structures, coordinate covalent bonding, and metallic bonding. |
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http://dwb.unl.edu/Chemistry/LearningObjectives/TX_chem.html
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| Â | Abstract - Contributions of solvent-solvent hydrogen bonding and van der Waals interactions to the attraction between methane molecules in water |
| | The magnitude of the attraction between methanes was not significantly changed when the hydrogen bonding interaction between solvent molecules was eliminated and the solvent was maintained in the liquid state by increasing either the pressure or the magnitude of the solvent-solvent van der Waals interaction. | | | The results are consistent with the idea that the primary contribution of hydrogen bonding to the hydrophobic interaction is to keep water molecules in a liquid state; at constant density, packing interactions rather than hydrogen bonding appear to be critical as suggested by scaled particle theories of solvation. | | | The overall shape of the PMF was, however, changed in the absence of hydrogen bonding, pointing to an influence of hydrogen bonding on the detailed form of the interactions between nonpolar solutes in water. |
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http://depts.washington.edu/bakerpg/abstracts/Rank-BiophysChem-v71-p199.html
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| Â | HYBOT-PLUS - Hydrogen bond thermodynamics. Calculation of local and molecular physicochemical descriptors |
| | HYBOT consists of three major components: (i) a database of over 13,500 thermodynamic measurements of hydrogen bonding systems, (ii) a H-bond factor database (about 60,000 entries), and (iii) a computer program that estimates H-bond factor values for compounds on the basis of their structures. | | | HYBOT (HYdrogen BOnd Thermodynamics) is designed to aid chemists, biochemists, pharmacologists, physiologists and other specialists interested in hydrogen bonding phenomena. | | | a hydrogen bond thermodynamics database containing experimental free energies and enthalpies of hydrogen bonding complexes in various solvents |
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http://www.timtec.net/software/hybot-plus.htm
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| Â | Macatea: Blue Jeans and the Hydrogen Bond |
| | The terminal O and H atoms may engage in hydrogen bonding with atoms of a solvent (intermolecular hydrogen bonding) or they may hydrogen bond with one another (intramolecular hydrogen bonding). | | | Hydrogen bonding is one type of charge transfer. | | | In the vapor phase, there is little of either kind of hydrogen bonding, and indigo appears red. |
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http://www.macatea.com/workshop/bluejeans.shtml
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| Â | intermolecular bonding - hydrogen bonds |
| | The hydrogen bonding in the ethanol has lifted its boiling point about 100°C. It is important to realise that hydrogen bonding exists in addition to van der Waals attractions. | | | Except in some rather unusual cases, the hydrogen atom has to be attached directly to the very electronegative element for hydrogen bonding to occur. | | | The diagram shows the potential hydrogen bonds formed to a chloride ion, Cl Although the lone pairs in the chloride ion are at the 3-level and wouldn't normally be active enough to form hydrogen bonds, in this case they are made more attractive by the full negative charge on the chlorine. |
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http://www.chemguide.co.uk/atoms/bonding/hbond.html
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| Â | Molecular vibration and absorption of water molecules |
| | In liquid water the molecular stretch vibrations shift to higher frequency, on raising the temperature (as hydrogen bonding weakens, the covalent O-H bonds strengthen causing them to vibrate at higher frequencies) whereas the intramolecular vibrations shift to lower frequencies and the molecular bend vibration peak both shifts to lower frequencies and becomes narrower [696]. | | | The strength of the hydrogen bonding depends on the cooperative/anticooperative nature of the surrounding hydrogen bonds with strongest hydrogen bonds giving the lowest vibrational frequencies [852]. | | | 970-1940 nm) are suited to rapid non-destructive water determination [479], all shifting a few nm to longer wavelength (lower frequency) with strengthening hydrogen bonding due to shifts from high density water (i.e. |
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http://www.lsbu.ac.uk/water/vibrat.html
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| Â | Abstract - Contributions of solvent-solvent hydrogen bonding and van der Waals interactions to the attraction between methane molecules in water |
| | The magnitude of the attraction between methanes was not significantly changed when the hydrogen bonding interaction between solvent molecules was eliminated and the solvent was maintained in the liquid state by increasing either the pressure or the magnitude of the solvent-solvent van der Waals interaction. | | | The results are consistent with the idea that the primary contribution of hydrogen bonding to the hydrophobic interaction is to keep water molecules in a liquid state; at constant density, packing interactions rather than hydrogen bonding appear to be critical as suggested by scaled particle theories of solvation. | | | The overall shape of the PMF was, however, changed in the absence of hydrogen bonding, pointing to an influence of hydrogen bonding on the detailed form of the interactions between nonpolar solutes in water. |
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http://depts.washington.edu/bakerpg/abstracts/Rank-BiophysChem-v71-p199.html
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| Â | struct.doc |
| | [k] Can I describe, interpret and/or predict the effects of different types of bonding (ie ionic bonding, covalent bonding, hydrogen bonding, other intermolecular interactions, metallic bonding) on the physical properties of substances? | | | [b] Can I describe, including the use of ‘dot and cross’ diagrams’ [i] covalent bonding, as in hydrogen, oxygen, chlorine, hydrogen chloride, carbon dioxide, methane, ethene; [ii] co-ordinate (dative covalent) bonding as in BF3.NH3 ? | | | They should learn that the properties of a bulk material are intimately and ineluctably connected with the details of their inner bonding and wider structures. |
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http://www.marling.gloucs.sch.uk/chemistryweb/Schedule/struct.doc
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| Â | Hydrogen bonds in water |
| | Hydrogen bonding occurs when an atom of hydrogen is attracted by rather strong forces to two atoms instead of only one, so that it may be considered to be acting as a bond between them [ 99 ]. | | | The molecular orbitals involved in the hydrogen bonding between two water molecules (50 KB) and five water molecules (29 KB) in a cyclic pentamer are given on other pages. | | | Hydrogen bonding rearrangement offers a low energy pathway for the transfer of hydrogen atoms during tautomerism, in a way similar to Grotthuss mechanism for hydrogen ion transport. |
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http://www.lsbu.ac.uk/water/hbond.html
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| Â | Hydrogen bonds in water |
| | Cooperative hydrogen bonding increases the O-H bond length whilst causing a 20-fold greater reduction in the H····O and O····O distances [436]. | | | Hydrogen bonding occurs when an atom of hydrogen is attracted by rather strong forces to two atoms instead of only one, so that it may be considered to be acting as a bond between them [99]. | | | one of the hydrogen bonds in ice-four (143°). |
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http://www.lsbu.ac.uk/water/hbond.html
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| Â | Hydrogen bonds in water |
| | Hydrogen bonding occurs when an atom of hydrogen is attracted by rather strong forces to two atoms instead of only one, so that it may be considered to be acting as a bond between them [99]. | | | Hydrogen bonding rearrangement offers a low energy pathway for the transfer of hydrogen atoms during tautomerism, in a way similar to Grotthuss mechanism for hydrogen ion transport. | | | An interesting way of describing the cooperative/anticooperative nature of the water dimer hydrogen bond is to use the nomenclature d'a'DAd''a'' where DA represents the donor-acceptor nature of the hydrogen bond, the d'a' represents the remaining donor-acceptor status of the donating water molecule and d''a'' represents the remaining donor-acceptor status of the accepting water molecule [852]. |
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http://www.lsbu.ac.uk/water/hbond.html
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| Â | PPS - Hydrogen Bonds II |
| | An important resource for studying hydrogen bonding in proteins is the UCL Atlas of Side-Chain and Main-Chain Hydrogen Bonding. | | | However, when a residue is buried in the core, hydrogen bonding potential is usually more completely satisfied than for residues on the surface; there are distinct differences between the individual amino acids in this respect. | | | In the reduced form it can act as a donor in one hydrogen bond, and as an acceptor in two, although in practice it only appears to be a donor. |
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http://pps98.man.poznan.pl/ppscore/section7/hbond2.html
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| Â | Magnetic and electric effects on water |
| | Due to the fine balance between the conflicting hydrogen bonding and non-bonded interactions in water clusters, any such weakening of the van der Waals attraction leads to a further strengthening of the hydrogen bonding and greater cyclic hydrogen bonded clustering. | | | The balance between hydrogen bonding and van der Waals attractions is thus biased towards van der Waals attractions giving rise to less cyclic hydrogen bonded clustering. | | | In addition to the breakage of hydrogen bonds electromagnetic fields may perturb in the gas/liquid interface and produce reactive oxygen species [110]. |
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http://www.lsbu.ac.uk/water/magnetic.html
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| Â | Rotamer Exploration and Prediction |
| | Examples of this phenomenon are shown in figure 4, where the green regions are areas with a high statistical preference for hydrophobic contacts, and the red regions have a high preference for hydrogen-bonding contacts. | | | Each atom in the rotamer and the environment is classified as either: hydrogen-bonding (donor), hydrogen-bonding (acceptor), hydrogen-bonding (both), hydrophobic, or polar. | | | Although the Rotamer Explorer also reports the change in hydrophobic surface area (the integral of hydrophobic character over all exposed surface) and explicit hydrogen bonds, these do not factor into the deltaG scoring function. |
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http://www.chemcomp.com/Journal_of_CCG/Features/rotexpl.htm
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| Â | Energy variables |
| | In this case it is the radius of the hydrogen-bonding hydrogens which is reduced, rather than the radius of the central nitrogen itself. | | | Thus the EXTENDED hydroxyl group has a van der Waals radius of 1.65 Angstrom which is reduced by 0.25 Angstrom to a hydrogen bonding radius of 1.40 Angstrom. | | | The Concept of a hydrogen-bonding radius RMININ between two identical atoms is still used, even if the atoms would not actually hydrogen bond to each other. |
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http://www.moldiscovery.com/docs/grid/c40.html
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| Â | Messages from GRID at run time |
| | RMINJ is the hydrogen-bonding radius of the Probe, corresponding to the hydrogen bonding radius RMIN(I) of the hydrogen-bonding heavy atom in the Target molecule. | | | Edit that file, and move the heavy atom in the second record into a position above the hydrogen record at the start of the file, or move the penultimate heavy atom into the final row of the file, as the case may be. | | | All of the hydrogen atoms which are to be included in the Target must occur at the end of file GRINKOUT, in the correct sequence which is determined by the sequence of ATOMS and HETATMS in the original PDB file. |
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http://www.moldiscovery.com/docs/grid/c77.html
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| Â | Molecular Interactions Between Inhaled Anesthetics and Proteins -- Eckenhoff and Johansson 49 (4): 343 -- Pharmacological Reviews |
| | Panel (f) represents an intrapeptide bond between a carbonyl oxygen and an amide hydrogen, with an anesthetic acting as a hydrogen donor, the implication being that the anesthetic may interact favorably with this group through hydrogen bonding without disruption of the native hydrogen bond. | | | Panels (a) through (d) represent hydrogen bonding between anesthetic halogens and amid hydrogens, or peripheral aromatic ring hydrogens. | | | Hydrogen bonds have a central role in protein structure, stability, and function (Fersht et al., 1985 |
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http://pharmrev.aspetjournals.org/cgi/content/full/49/4/343
(16563 words)
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| Â | Hydrogen Bonds |
| | The polarity of the water molecule with the attraction of the positive and negative partial charges is the basis for the hydrogen bonding. | | | To recognize the possibility of hydrogen bonding, examine the Lewis structure of the molecule. | | | A hydrogen bond is the attractive force between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule. |
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http://www.elmhurst.edu/~chm/vchembook/161Ahydrogenbond.html
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| Â | Unique Properties of Water |
| | Because of the hydrogen bonding it is very difficult to separate the water molecules from the surface of a liquid to form a vapor. | | | The reason for the high melting and boiling temperatures is the hydrogen bonding between water molecules that causes them to stick together and to resist being pulled apart which is what happens when ice melts and water boils to become a gas. | | | In the case of liquid water, because the hydrogen bonds suppress vibration, the temperature does not increase as much as it would without the presence of strong hydrogen bonds. |
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http://core.ecu.edu/geology/woods/H2OUNEEK.htm
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| Â | Roger A. Lalancette |
| | Roger A. Lalancette, Hugh W. Thompson and Andrew P. Brunskill, "(+)22,23-Bisnor-3-Oxo-5alpha-Cholanic Acid: Hydrogen-Bonding Patterns in a Steroidal Keto Acid and its Monohydrate", Acta Cryst., 1997, C53, 421-424. | | | Roger A. Lalancette, Andrew P. Brunskill and Hugh W. Thompson, "(±)2,-3-Dihydro-3-Oxo-1H-Indenecarboxylic Acid: Hydrogen-Bonding Patterns in a gamma Keto Acid and its Monohydrate", Acta Cryst., 1997, C53, 1838-1842. | | | Roger A. Lalancette, Hugh W. Thompson, and Marie L. Cote', "Hydrogen-Bonding Pattern of an alpha,beta-Unsaturated delta-Keto Acid: 1',3'-Dihydro-2-Methyl-6-Oxospiro[2-Cyclohexene-1,2'- 2'H-Indene]-3-Carboxylic Acid", Acta Cryst., 1997, C53, 901-903. |
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http://chemistry.rutgers.edu/faculty/lalancette.html
(1091 words)
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| Â | A Study on Structure and Mechanism of Diurea Grease |
| | The structure of diurea grease is the essential reason that affects its dropping point, and hydrogen bonding affects the structure. | | | Hydrogen bonding forced diurea molecules to be arranged in order and a stable structure was formed at last. | | | Hydrogen bonding was found among diurea molecules by using FTIR and the amount of hydrogen bonding increased in some range of container temperature. |
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http://www.nlgi.com/0219.htm
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| Â | Phase diagram of water and ice |
| | Although primarily ordered or disordered, ordered arrangements of hydrogen bonding may not be perfect and disordered arrangements of hydrogen bonding are not totally random as there are correlated and non-bonded preferential effects. | | | In all cases the two hydrogen atoms are equivalent, with the water molecules retaining their symmetry, and they all obey the 'ice' rules: two hydrogen atoms near each oxygen, one hydrogen atom on each O····O bond. | | | Beyond the critical point in the liquid-vapor space (towards the top right, above), water is supercritical existing as small but liquid-like hydrogen-bonded clusters dispersed within a gas-like phase [ 456 ], where physical properties, such as gas-like or liquid-like behavior, vary in response to changing density. |
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http://www.sbu.ac.uk/water/phase.html
(1091 words)
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