Activation of the Hydrogen-Terminated Diamond [100] by Hydrogen Atoms and Hydroxyl Groups

2020 ◽  
Vol 996 ◽  
pp. 151-156
Author(s):  
Xiao Gang Jian ◽  
Ji Bo Hu ◽  
Xin Huang ◽  
Pei Kang Yang ◽  
Jun Peng Wang
Keyword(s):  
Hydrogen Atom ◽  
Low Temperature ◽  
Density Functional ◽  
Diamond Surface ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Hydrogen Atoms ◽  
Activation Rate ◽  
Limiting Stage ◽  
Rate Limiting

The process of producing active vacancies on a hydrogen-terminated diamond surface is the most important rate-limiting stage in CH4/H2 and CH4/H2/CO2 atmospheres. Hydrogen atom and the hydroxyl group can bone to the hydrogen atom on the diamond surface and create an active vacancy. Density functional theory (DFT) was used to study the extraction reaction by two reactants both hydrogen atom and the hydroxyl group. The result indicated that the hydroxyl group could reduce the energy required for diamond surface activation. What is more, the activation rate of the surface by the hydroxyl group was livelier at low temperature, while the activation rate of the hydrogen atom predicts on the contrary. The scanning electron microscope (SEM) and Raman spectra demonstrated that the introduction of CO2 in the CH4/H2 atmosphere could reduce the deposition temperature and raise the deposition rate at low temperature.

scholarly journals Effects of Hydroxyl Group on the Interaction of Carboxylated Flavonoid Derivatives with S. Cerevisiae α-Glucosidase

2020 ◽  
Vol 16 (1) ◽  
pp. 31-44
Author(s):  
Huining Lu ◽  
Yanjiao Qi ◽  
Yaming Zhao ◽  
Nengzhi Jin
Keyword(s):  
Hydrogen Atom ◽  
Charge Density ◽  
Density Functional ◽  
Noncovalent Interactions ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Binding Affinities ◽  
Functional Theory ◽  
Density Analysis ◽  
Hydroxyl Hydrogen

Introduction: Carboxyalkyl flavonoids derivatives are considered as effective inhibitors in reducing post-prandial hyperglycaemia. Methods: Combined with Density Functional Theory (DFT) and the theory of Atoms in Molecules (AIM), molecular docking and charge density analysis are carried out to understand the molecular flexibility, charge density distribution and the electrostatic properties of these carboxyalkyl derivatives. Results: Results show that the electron density of the chemical bond C14-O17 on B ring of molecule II increases while O17-H18 decreases at the active site, suggesting the existence of weak noncovalent interactions, most prominent of which are H-bonding and electrostatic interaction. When hydroxyl groups are introduced, the highest positive electrostatic potentials are distributed near the B ring hydroxyl hydrogen atom and the carboxyl hydrogen atom on the A ring. It was reported that quercetin has a considerably inhibitory activity to S. cerevisiae α-glucosidase, from the binding affinities, it is suggested that the position and number of hydroxyl groups on the B and C rings are also pivotal to the hypoglycemic activity when the long carboxyalkyl group is introduced into the A ring. Conclusion: It is concluded that the presence of three well-defined zones in the structure, both hydrophobicity alkyl, hydrophilicity carboxyl and hydroxyl groups are necessary.

scholarly journals Molecular Modeling of Ammonia Gas Adsorption onto the Kaolinite Surface with DFT Study

Minerals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 46 ◽  
Author(s):  
Qi Cheng ◽  
Yongbing Li ◽  
Xiaojuan Qiao ◽  
Yang Guo ◽  
Yang Zhao ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Density Functional ◽  
Gas Adsorption ◽  
Hydroxyl Group ◽  
Partial Density ◽  
Hydroxyl Groups ◽  
High Porosity ◽  
Ammonia Gas ◽  
Nh3 Adsorption ◽  
Kaolinite Surface

With high porosity and being one of the most abundant clay minerals, dried kaolinite may be an excellent adsorbent to remove ammonia gas (NH3). Here, the plane wave pseudopotential method based on density functional theory (DFT) was used to explore the mechanism of ammonia gas adsorption on the dried kaolinite, the Mulliken electric charge, and the partial density of states of atoms of the NH3/kaolinite (001) system. NH3 adsorption on kaolinite can happen in three different type adsorption positions: “top”, “bridge” and “hollow”. The “hollow” position is enclosed by two "upright" hydroxyl groups perpendicular to the (001) surface of kaolinite and a "lying" hydroxyl group parallel to the surface. At this position, the adsorption is the most stable and has the highest adsorption energy. The nitrogen atom of the NH3 molecule bonds with the hydrogen atom in the "upright" hydroxyl group on the (001) surface and its hydrogen atom forms HN…O hydrogen bond with oxygen atom in the "lying" hydroxyl group, which leads to the NH3 stably adsorbed on kaolinite (001) surface. A small part of electrons transfer between NH3 molecules and kaolinite creates weakly electrostatic adsorption between them.

Crystal structure of atropine sulfate monohydrate, (C17H24NO3)2(SO4)·(H2O)

2019 ◽  
Vol 34 (4) ◽  
pp. 389-395 ◽  
Author(s):  
James A. Kaduk ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Water Molecule ◽  
Powder Diffraction ◽  
Density Functional ◽  
Atropine Sulfate ◽  
Strong Hydrogen Bond ◽  
Hydroxyl Groups ◽  
Hydrogen Atoms ◽  
Sulfate Anion

The crystal structure of atropine sulfate monohydrate has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Atropine sulfate monohydrate crystallizes in space group P21/n (#14) with a = 19.2948(5), b = 6.9749(2), c = 26.9036(5) Å, β = 94.215(2)°, V = 3610.86(9) Å3, and Z = 4. Each of the two independent protonated nitrogen atoms participates in a strong hydrogen bond to the sulfate anion. Each of the two independent hydroxyl groups acts as a donor in a hydrogen bond to the sulfate anion, but only one of the water molecule hydrogen atoms acts as a hydrogen bond donor to the sulfate anion. The hydrogen bonds are all discrete but link the cations, anion, and water molecule along [101]. Although atropine and hyoscyamine (atropine is racemic hyoscyamine) crystal structures share some features, such as hydrogen bonding and phenyl–phenyl packing, the powder patterns show that the structures are very different. The powder pattern for atropine sulfate monohydrate has been submitted to ICDD for inclusion in the Powder Diffraction File™.

scholarly journals Hydroxyl-Group Identification Using O K-Edge XAFS in Porous Glass Fabricated by Hydrothermal Reaction and Low-Temperature Foaming

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3488 ◽  
Author(s):  
Masanori Suzuki ◽  
Shigehiro Maruyama ◽  
Norimasa Umesaki ◽  
Toshihiro Tanaka
Keyword(s):  
Low Temperature ◽  
Surface Area ◽  
Porous Glass ◽  
Hydrothermal Reaction ◽  
Group Identification ◽  
Fluorescence Yield ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Xafs Spectroscopy

Porous glass was prepared by the hydrothermal reaction of sodium borosilicate glass, and oxygen-ion characterization was used to identify the hydroxyl groups in its surface area. A substantial amount of “water” was introduced into the ionic structure as either OH− groups or H2O molecules through the hydrothermal reaction. When the hydrothermally treated glass was reheated at normal pressures, a porous structure was formed due to the low-temperature foaming resulting from the evaporation of H2O molecules and softening of the glass. Although it was expected that the OH− groups would remain in the porous glass, their distribution required clarification. Oxygen K-edge X-ray absorption fine structure (XAFS) spectroscopy enables the bonding states of oxygen ions in the surface area and interior to be characterized using the electron yield (EY) and fluorescence yield (FY) mode, respectively. The presence of OH− groups was detected in the O K-edge XAFS spectrum of the porous glass prepared by hydrothermal reaction with a corresponding pre-edge peak energy of 533.1 eV. In addition, comparison of the XAFS spectra obtained in the EY and FY modes revealed that the OH− groups were mainly distributed in the surface area (depths of several tens of nanometers).

AN INVESTIGATION OF THE CHLORINATION OF SPRUCE WOOD AND OF THE RESULTING CHLOROLIGNIN

1937 ◽  
Vol 15b (7) ◽  
pp. 279-294 ◽  
Author(s):  
G. V. Jansen ◽  
J. W. Bain
Keyword(s):  
Methyl Alcohol ◽  
Ring Structure ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Hydrogen Atoms ◽  
Chlorine Atoms ◽  
Spruce Wood ◽  
Simple Substitution ◽  
Homogeneous Fraction ◽  
Acid Reduction

Spruce sawdust was chlorinated under various conditions in an attempt to procure a homogeneous lignin chloride. Success finally attended the use of methyl alcohol as a medium for chlorination. The lignin chloride, which was dissolved by the alcohol during the chlorination and subsequently precipitated by the addition of water, was cream white in color, and analysis showed it to be an alcohol lignin.A homogeneous fraction (No. 2) was obtained from the re-chlorinated product, and it proved to be a chlorinated analogue of Hibbert's monomethylated methyl alcohol lignin, the formulas of the two products being C42H22O6Cl13(OH)2(OCH3)7, and C42H32O6(OH)3(OCH3)7. The molecular weight and the presence of the two hydroxyl groups were confirmed by acetylation, when 2.0 acetyl groups entered the molecule. Eleven of the chlorine atoms in Fraction 2 have evidently replaced ten hydrogen atoms and one hydroxyl group by simple substitution in methyl alcohol lignin, leaving two chlorine atoms which have apparently entered to saturate a double bond. Seven of these chlorine atoms have been shown to be readily removable either by an alkali or by acid reduction. The other six, because of their stable union with the molecule, are surmised to be joined to an aromatic nucleus or at least to some type of ring structure. The product has been shown to react stoichiometrically within limits as narrow as could be expected for such a large molecule.

Structure of Cerebrosides. II. Small Angle X-Ray Diffraction Study of Cerasine

1979 ◽  
Vol 34 (12) ◽  
pp. 1121-1124 ◽  
Author(s):  
R. Hosemann ◽  
J. Loboda-Čačković ◽  
H. Čačković ◽  
S. Fernandez-Bermúdez ◽  
F. J. Baltá-Calleja
Keyword(s):  
Molecular Weight ◽  
Fatty Acid ◽  
Hydrogen Atom ◽  
Low Temperature ◽  
Hydroxyl Group ◽  
X Ray Diffraction ◽  
Orientational Disorder ◽  
X Ray ◽  
Long Period ◽  
Lattice Planes

Cerasine having a molecular weight of 800 differs chemically from phrenosine only in the hydroxyl group attached to the fatty acid tail which is replaced by a hydrogen atom. Nevertheless, remarkable differences between both cerebrosides are detected in the lamellae periodicities. In the range of 23 - 66 °C just one single (instead of two) structure with a similar subcell to the triclinic one component of phrenosine is detected. Between 66 and 87 °C three new components (instead of one in phrenosine) appear. Two of the structures are similar to the two phrenosine-components at low temperature and the tilt angles of their chains with respect to the basal planes can explain the stabilizing capacity of the 201 and 301 netplanes of the paraffin-like subcells respectively. These lattice planes are parallely aligned to the surfaces of the lamellae. The long period of 58 Å of component II cannot be explained in such a wav. This period persits upto 105 °C and coexists from 87 °C with a new component showing a 40 Å-periodicity, which cannot either be explained in the above manner. Paracrystalline distortions of the arrangement of the bilayers can be justified by orientational disorder of the galactose heads.

Modelling methanogenesis during anaerobic conversion of complex organic matter at low temperatures

1997 ◽  
Vol 36 (6-7) ◽  
pp. 531-538 ◽  
Author(s):  
V. A. Vavilin ◽  
L. Ya. Lokshina ◽  
S. V. Rytov ◽  
O. R. Kotsyurbenko ◽  
A. N. Nozhevnikova ◽  
...  
Keyword(s):  
Organic Matter ◽  
Low Temperature ◽  
Wetland Soil ◽  
Methane Formation ◽  
Tundra Soil ◽  
Alternative Pathways ◽  
Wide Range ◽  
Limiting Stage ◽  
Acetoclastic Methanogenesis ◽  
Rate Limiting

Low temperature consumption of H2/CO2 by microflora of tundra wetland soil and pond silt were simulated using the modified <METHANE> model with consideration of homoacetogens or hydrogen consuming methanogens as hydrogenotrophs. Simulations show that the model with homoacetogens was able to fit the data closely. Under the conditions of high initial hydrogen concentrations acetate was the main precursor of methane. Inhibition of acetoclasic methanogens proved to be significant for tundra soil samples. Methane formation from organic matter contained in the samples of tundra soil was modeled in the wide range of temperature conditions. It was concluded that hydrolysis is the rate-limiting step at 10–28°C, but at 6°C the rate of acetoclastic methanogenesis becomes the rate-limiting stage in methane production. To describe the low temperature methane formation from organic matter by microflora of pond silt, cattle's and pig's manure the alternative pathways with participation of homoacetogens or hydrogenotrophic methanogens were verified. It was shown that the both pathways fit the measured data comparatively well.

scholarly journals SIGNIFICANCE OF THE HYDROXYL GROUPS OF STEROIDS IN PROMOTING GROWTH

1954 ◽  
Vol 100 (3) ◽  
pp. 241-246 ◽  
Author(s):  
Charles Huggins ◽  
Elwood V. Jensen
Keyword(s):  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Critical Importance ◽  
Hydrogen Atoms ◽  
Albino Rat ◽  
Ketone Group ◽  
Related Compounds

The presence of a 17ß-hydroxyl group endows the simple androstane molecule with the ability to produce growth of the uterus, vagina, and prostate of the female hypophysectomized albino rat. It appears that hydrogen atoms at position 17 are of critical importance since related compounds with a ketone group at this site are inactive. Monofunctional steroids with a hydroxyl or a ketone group at position 3 likewise are devoid of activity. If a phenolic A-ring is present in monofunctional steroids the 17ß-hydroxyl group is not obligatory for growth. Proliferation of the uterus and vagina were found to follow the administration of 17-desoxyestradiol.

Conformation of the esters of steroid hydroxyl groups by infrared spectroscopy

1969 ◽  
Vol 47 (9) ◽  
pp. 1601-1603 ◽  
Author(s):  
C. R. Narayanan ◽  
M. R. Sarma ◽  
T. K. K. Srinivasan ◽  
M. S. Wadia
Keyword(s):  
Hydrogen Bonding ◽  
Infrared Spectroscopy ◽  
Carbonyl Group ◽  
Hydroxyl Group ◽  
Spectral Studies ◽  
Hydroxyl Groups ◽  
Hydrogen Atoms ◽  
Infrared Spectral

Infrared spectral studies show that the carbonyl group of the esters of steroid hydroxyl groups are stabilized near the adjacent alkyl hydrogen atoms; this energy of stabilization appears to be more than that of hydrogen bonding between the carbonyl and a nearby hydroxyl group.

Towards clathrates. 2. The frozen states of hydration of tert-butanol

2018 ◽  
Vol 233 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Lukasz Dobrzycki
Keyword(s):  
Single Crystal ◽  
Crystalline Phase ◽  
Ambient Pressure ◽  
Water System ◽  
Hydroxyl Group ◽  
Molar Ratio ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Hydrogen Atoms ◽  
Ir Laser

AbstractA new crystal structure oftert-butanol and water crystallizing as the decahydrate is reported. The crystallization of the mixture in the desired molar ratio was performed in a capillary placed directly on a goniometer of a single crystal diffractometer at 200 K and ambient pressure using focused IR laser radiation. The crystals were grown while the melting zone formed by the IR laser was moved along the capillary. Usually the crystallization process should be long enough (hours) in order to obtain a good quality single crystal. However, in the case oftert-butanol decahydrate, such a long process led to separation of the ice and alcohol. Only fast crystallization taking tens of seconds allowed crystallization of the desired crystalline phase. In the decahydratetert-butanol molecules are located in channels formed by water molecules. Hydroxyl groups are anchored to the water framework via hydrogen bonds. All water molecules in the structure have hydrogen atoms disordered equally over two sites; the hydroxyl group is likewise disordered. This effect is observed at both, 200 K and 100 K. Raman spectra recorded for the crystalline phase suggest dynamic disorder at higher temperature, converting to static at lowerT. The decahydrate oftert-butanol, together with already known itsdi- andhepta-hydrates, display similar features to those observed for series oftert-butylamine hydrates. The latter structures behave as frozen steps of amine hydration observed as crystal structures leading, at maximum dilution, to hexagonal ice. Hydrates oftert-butanol nicely follow this tendency completing the relationship found for thetert-butylamine: water system.

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