• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3
  • 1
  • 1
  • Tagged with
  • 8
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

New Strategies for Stereoselective Preparation of Densely Functionalized Cyclobutanes:

Yang, Xinyu January 2022 (has links)
Thesis advisor: Shih-Yuan Liu / This dissertation describes the utility of 1,2-azaborine motif as a 4C+1B+1N synthon in organic synthesis, especially for the preparation of densely functionalized cyclobutanes based on the framework of the 1,2-azaborine photoisomerization. The substitution of a CC unit with a BN unit in benzenes significantly modifies the properties of classic benzenoid compounds, leading to new reactivities and functionalities. In this vein, Chapter 1 discloses photoisomerization of 1,2-azaborines to selectively form BN-analogues of the Dewar benzene. Three applications of the Dewar photoisomers are described herein: 1) a rhodium-catalyzed ring-opening reaction to form 1,2-azaborines; 2) furnishing cis aminoborylated cyclobutanes with the boron unit as a further functionalization handle; 3) a stereospecific ring-opening reaction to afford diene which can engage in Diels-Alder reaction. Chapter 2 elaborates on a modular and stereoselective strategy to access a variety of cyclobutane β-amino alcohols. Discussed herein are regioselective functionalizations and di-functionalizations of the 1,2-azaborine core and a tandem photoisomerization-hydrogenation-oxidation protocol to translate the functionalized azaborine core to cyclobutane amino alcohols. Also examined herein are the scope of azaborine photoisomerization and Dewar hydrogenation. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.
2

The study of the transition metal complexes of benzene and dewar benzene derivatives

Yeh, Po-Chen 31 July 2000 (has links)
none
3

Density Functional Theory Study of Vibrational Spectra, 6: Assignment of Fundamental Vibrational Frequencies of Benzene Isomers: Dewar Benzene, Benzvalene, Trimethylenecyclopropane, Prismane, and 3,4-Dimethylenecyclobutene

Zhou, Xuefeng, Liu, Ruifeng 01 January 1997 (has links)
The molecular structures and vibrational spectra of Dewar benzene, benzvalene, trimethylenecyclopropane, prismane and 3,4-dimethylenecyclobutene have been investigated by density functional theory using Becke's exchange with Lee-Yang-Parr's correlation functional and the 6-31G* basis set. Both the calculated structural parameters and vibrational frequencies are in good agreement with available experimental data. On the basis of the agreement between the calculated and experimental results, assignments of fundamental vibrational frequencies of Dewar benzene, benzvalene, and trimethylenecyclopropane were examined and some reassignments are proposed. The calculations also predict prominent IR and Raman spectral features of prismane and 3,4-dimethylenecyclobutene, which can assist experimental identification of these compounds and the assignment of observed spectral features when they are available.
4

Design of a Highly Constrained Test System for a 12-bit, 16-channel Wilkinson ADC

Pannell, Zachary William 01 December 2009 (has links)
Outer space is a very harsh environment that can cause electronics to not operate as they were originally intended. Aside from the extreme amount of radiation found in space, temperatures can also change very dramatically in a relatively small time frame. In order to test electronics that will be used in this environment, they first need to be tested on Earth under replicated conditions. Vanderbilt University designed a dewar that allows devices to be tested at these extreme temperatures while being radiated. For this thesis, a test setup that met all of the dewar's constraints was designed that would allow a 12-bit, 16-channel analog-to-digital converter to be tested while inside.
5

Design of a Highly Constrained Test System for a 12-bit, 16-channel Wilkinson ADC

Pannell, Zachary William 01 December 2009 (has links)
Outer space is a very harsh environment that can cause electronics to not operate as they were originally intended. Aside from the extreme amount of radiation found in space, temperatures can also change very dramatically in a relatively small time frame. In order to test electronics that will be used in this environment, they first need to be tested on Earth under replicated conditions. Vanderbilt University designed a dewar that allows devices to be tested at these extreme temperatures while being radiated. For this thesis, a test setup that met all of the dewar's constraints was designed that would allow a 12-bit, 16-channel analog-to-digital converter to be tested while inside.
6

Solid-state spin-1/2 NMR studies of disorder, bonding, and symmetry

Harris, Kristopher J. Unknown Date
No description available.
7

Solid-state spin-1/2 NMR studies of disorder, bonding, and symmetry

Harris, Kristopher J. 11 1900 (has links)
This thesis is concerned with applications of modern solid-state NMR spectroscopy. Investigations of three quite different types are undertaken, each of which attempt to advance knowledge in the fields of chemistry and NMR. The goal of each project is to obtain insight into the effects of chemical environment, in particular bonding, on the NMR observables. Carbon-13 and nitrogen-15 solid-state nuclear magnetic resonance has been used to study solid samples containing the dicyanoaurate(I) anion, [Au(CN)2]-, with n-butylammonium, potassium, and thallium counterions. Differences in Au-Tl metallophilic bonding are shown to cause a difference in the isotropic cyanide carbon-13 chemical shift of up to 15.7 ppm, while differences in Au-Au aurophilic bonding are found to be responsible for a change of up to 5.9 ppm. Disordered polymeric gold(I) monocyanide was also investigated, and a range of 7+-2% to 25+-5% of the AuCN chains are found to be "slipped" instead of aligned with the neighbouring chains at the metal position. An investigation of the chemical shift tensors of the 13C-labelled carbons in solid samples of Ph13C≡13CPh and (η2-Ph13C≡13CPh)Pt(PPh3)2·(C6H6) has also been carried out. Coordination of diphenylacetylene to platinum causes a change in the 13C chemical shift tensor orientation and a net increase in the isotropic chemical shift. The carbon chemical shift tensors in the platinum complex bear a striking similarity to those of the alkenyl-carbons in trans-Ph(H)C=C(H)Ph, and a theoretical discussion of these observations is presented. Each of the fundamental NMR interaction tensors (σ, J, D and V) may be decomposed into isotropic, symmetric, and antisymmetric components. Observations of all theoretically allowed components other than the antisymmetric portion of J (Janti) have previously been published. Andrew and Farnell's theory (Mol. Phys. 15, 157 (1968)) for the effects of Janti on NMR spectra has been extended to powdered samples, and methods for analyzing the resultant line shapes have been determined. Finally, the first reported experimental attempts to measure Janti are presented, and experimental proof that no elements of Janti(119Sn,119Sn) in hexa(p-tolyl)ditin are larger than 2900 Hz is given.
8

Vilseledning : Med bluffen som vapen

Boyle, Johan January 2016 (has links)
One of the most efficient countermeasures towards deception is awareness and knowledge that in fact deception is being performed. Hence, if the general level of knowledge within the main population of Sweden would be higher, it would probably hamper the effects of a deception operation if the population anticipated it. In order to counter deception, awareness that one could be encountered to deception and analyze the incoming information accordingly is a major protection. Furthermore in combination with mental awareness the counterdeception actions need to be managed from a central Swedish national level and well-coordinated between authorities within the governmental structures. This is in order to fully cover the wide spectra of channels of information that probably will be used within deception operations toward Sweden. The primary objective within a deception plan is to manipulate a human mind, not the technical sensors or systems.  Therefor the reasonable best way of counteract deception should lie within preparing the human mind. But paradoxological, the more aware one´s mind is regarding deception, the more one´s mind will discover deception.

Page generated in 0.0384 seconds