Sökning: "Hydrogen bonding"

Visar resultat 21 - 25 av 186 avhandlingar innehållade orden Hydrogen bonding.

1. 21. Physicochemical and Structural Aspects of Nucleic Acids

   Författare :Subhrangsu Chatterjee; Adolf Gogoll; Helena Grennberg; Göran Widmalm; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Organic chemistry; pKa; Hydrogen bonding; Stacking; NMR; MD; DNA; RNA; Pyrimidine; Organisk kemi;

   Sammanfattning : This thesis consists of seven research publications concerning (i) pKa studies of nucleobases in model nucleotides to understand why RNA duplexes are more stable than DNA duplexes (Paper I), (ii) the role of Me(T)-π interactions in the relative stability of DNA-RNA heteroduplexes (Paper II), (iii) pKa measurements in nucleotides with different 2′-substituents (paper III), (iv) a conformation study of constrained sugars and a pKa study of 1-thyminyl to reveal effect of sugar constraints on the pKa of the nucleobase (paper IV), (v) NMR and MD studies of 1′, 2′-oxetane constrained thymidine incorporated Dickerson Drew dodecamer (paper V), (vi) the sequence dependent pKa perturbation of 9-guaninyl moeity in single stranded (ss) DNA and RNA (paper VI), (vii) the non identical chemical nature of internucleotidic phosphates in (ss) RNA using 31P NMR (paper VI), and an alkaline hydrolysis study of phosphodiesters in ssRNAs (paper VII). The architecture of DNA and RNA molecules is determined by (a) hydrogen bonding (b) base stacking (c) a variety of additional non-covalent interactions. LÄS MER

3. 22. Molecular Structure and Packing of Platinum(II) Complexes with S-donor Ligands in the Solid State An X-ray Crystallographic Study

   Författare :Christian Hansson; Centrum för analys och syntes; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; low temperature; high-pressure; structural class concept; hydrogen bonding; intermolecular interactions; crystallography; platinum coordination compounds; packing; phase transitions; Inorganic chemistry; Oorganisk kemi;

   Sammanfattning : How do molecules arrange themselves in a crystal? It is today not possible to definite predict the three-dimensional packing arrangement of molecules in the crystalline solid state. The aim of the work presented in this thesis has been to gain more knowledge of what principles that govern molecular packing. LÄS MER

4. 23. Molecular 3D networks : self assembly of metal ions with bis-chelating ligands

   Författare :Krister Larsson; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; hydrogen bonding; networks; chirality; coordination chemistry; bis-chelating ligands; pi-pi-interactions; single crystal X-ray diffraction;

   Sammanfattning : .... LÄS MER

5. 24. Protons in In-doped BaZrO3: incorporation, distribution and local environments

   Författare :Laura Mazzei; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; hydrogen dynamics; hydrogen depth profiling; vibrational spectroscopy; neutron scattering; thin films; perovskites; Proton conductors;

   Sammanfattning : Acceptor doped proton conducting oxides are currently of large interest for their potential application as electrolyte materials in the future generation of solid oxide fuel cells. However, their proton conductivities are still lower than the target conductivity required for practical applications. LÄS MER

7. 25. The silicon nitride reaction-bonding process

   Författare :Bingqiang Lei; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Material Mechanics; Materialmekanik;

   Sammanfattning : The so called Reaction-Bonded Silicon Nitride (RBSN) materials are usually produced through the chemical reaction of silicon powder compacts in a nitriding atmosphere. This nitriding reaction is strongly exothermic and much heat is generated, which may cause to overheating, even melting of the powder compacts so to hinder the further reaction due to the reduction of specific area of the powder compacts, especially when the nitridation involves a rather large mass of silicon. LÄS MER