Relevant bibliographies by topics / Novel Crystal Structure / Dissertations / Theses

Dissertations / Theses on the topic 'Novel Crystal Structure'

To see the other types of publications on this topic, follow the link: Novel Crystal Structure.
Author: Grafiati
Published: 7 September 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'Novel Crystal Structure.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

Cosquer, Guirec Yann. "Liquid crystals with novel terminal chains as ferroelectric liquid crystal hosts." Thesis, University of Hull, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322457.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Koedtruad, Anucha. "SYNTHESIS OF NOVEL METAL HALIDES AND THEIR STRUCTURE-PROPERTY RELATIONS." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263484.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Lyle, Matthew John. "Crystal structure prediction and its application to novel metal oxides." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708224.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Clough, Andrew James. "Synthesis and crystal structure determination of novel lithium metal-organic frameworks." Thesis, California State University, Long Beach, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1524184.

Full text
Abstract:

In this thesis, three new lithium homometallic metal-organic frameworks are discussed. An introduction to lightweight metal-organic framework is given, followed by a detailed analysis of each new structure's topology, composition, novel secondary building units, and potential for gas adsorption. Special attention is given to the formation of new lithium secondary building units and the synthetic conditions that create them. These novel secondary building units are discussed in the context of the current lithium metal-organic framework literature, and compared when appropriate to known structures. Crystallography data is also discussed, with an emphasis on the connectivity of these lithium secondary building units.

APA, Harvard, Vancouver, ISO, and other styles
5

Carmel, Andrew Barry. "Crystal structure of BstDEAD, a novel DEAD-box protein from Bacillus stearothermophilus /." view abstract or download file of text, 2003. http://wwwlib.umi.com/cr/uoregon/fullcit?p3095239.

Full text
Abstract:
Thesis (Ph. D.)--University of Oregon, 2003.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 101-114). Also available for download via the World Wide Web; free to University of Oregon users.
APA, Harvard, Vancouver, ISO, and other styles
6

Isaza, Clara Eugenia. "Biochemical and structural characterization of novel metalloprotein sensors and carboxypeptidases." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1117548268.

Full text
Abstract:
Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xi, 98 p.; also includes graphics. Includes bibliographical references (p. 93-98). Available online via OhioLINK's ETD Center
APA, Harvard, Vancouver, ISO, and other styles
7

Chong, Samantha Yu-Ling. "Development of novel evolutionary algorithms for crystal structure determination from powder diffraction data." Thesis, University of Birmingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434699.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Nguyen, Phuong-Hieu T. "Design, synthesis, crystal structure and magnetic properties of novel osmium-based oxides in ordered rock salt structure type." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1601918.

Full text
Abstract:

AFM materials with triangular cationic sublattices give rise to geometric magnetic frustration. The goal of this project is to study frustrated systems by designed and synthesis of more frustrated systems. For this purpose, the 5d system of osmium transition metal oxide was chosen. The osmium-based compounds are then successfully synthesized using the conventional solid state method. The crystal structures are then characterized by different techniques such as X-ray diffraction and neutron diffraction. To determine the ordering of the crystal systems, magnetic susceptibility and heat capacity measurements are carried out. By employing the spin dimer analysis, magnetic exchange interactions are calculated. These novel osmium-based ordered rock salt structure type systems are then being compared to similar crystal systems in the text.

APA, Harvard, Vancouver, ISO, and other styles
9

Zhang, Shuo. "Analysis of Phase Transitions and Crystal Structures of Novel Benzothiophene Derivatives." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1449831649.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Leng, Siwei. "From Crystal to Columnar Discotic Liquid Crystal Phases: Phase Structural Characterization of Series of Novel Phenazines Potentially Useful in Organic Electronics." Akron, OH : University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1247614330.

Full text
Abstract:
Dissertation (Ph. D.)--University of Akron, Dept. of Polymer Science, 2009.
"August, 2009." Title from electronic dissertation title page (viewed 9/23/2009) Advisor, Stephen Z. D. Cheng; Committee members, Alexei P. Sokolov, Gustavo A. Carri, Darrell H. Reneker, Weiping Zheng; Department Chair, Ali Dhinojwala; Dean of the College, Stephen Z. D. Cheng; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
APA, Harvard, Vancouver, ISO, and other styles
11

Li, Bor-Ran. "Functional studies on a novel cytochrome c from Rhodobacter sphaeroides." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/3936.

Full text
Abstract:
SHP (Sphaeroides Heme Protein) is a monoheme cytochrome c of unknown function. In general, ligands cannot bind to ferric SHP, but some diatomic molecules, such as O2 or NO, can bind to ferrous SHP. The gene encoding SHP and genes encoding a diheme cytochrome c (DHC) and a b-type cytochrome (Cyt-b) are found in the same chromosome region in different species. In the case of Shewanella oneidensis MR-1, mRNA levels for SHP, DHC, and Cyt-b are up-regulated by nearly 10-fold when grown under anaerobic conditions using nitrate as the electron acceptor. Thus it is possible that the physiological role of SHP may be in nitrate metabolism. However, nitrate is too big to be a candidate substrate for SHP, and some nitrification steps need more than one electron transfer (SHP is a monoheme cytochrome). Therefore, we will focus on the nitrite reductase, nitric oxide reductase and nitric oxide dioxygenase activities of SHP. In this thesis it is shown that SHP can catalyse the reaction between oxygen and nitric oxide to give a nitrate ion as the final product. Thus a possible aerobic function for SHP as a nitric oxide dioxygenase is proposed. Aerobically, SHP is proposed to be a nitric oxide dioxygenase which utilizes the same mechanism as other NO dioxygenases, flavohemoglobin (HMP) and neuroglobin (Ngb). This mechanism is proposed to proceed via an oxy-ferrous complex (SHP2+-O2) which reacts with nitric oxide. A mechanism for the catalytic reaction with ferrous-NO complex is described. SHP2+-NO can be quickly converted back to ferrous SHP by reacting with superoxide liberated by SHP2+-O2 or from another source. In addition it is also found that Shewanella MR-1 wild type reveals a higher NO tolerance than the SHP knockout strain in aerobic conditions. The catalytic mechanism of NO dioxygenase is oxygen-dependent, but the SHP mRNA up-regulation in Shewanella oneidensis MR-1 grown with nitrate under anaerobic conditions indicates that SHP may also perform some anaerobic function and may possibly be involved in nitrate metabolism. This work found that SHP reveals anaerobic nitrite reductase activity. However, the catalytic efficiency of SHP is considerably lower than other nitrite reductases. This infers that although SHP can reduce nitrite in vitro, it is unlikely to function as a nitrite reductase in vivo. Ferrous SHP binds NO with a Kd of less than 1 μM, and does not auto-oxidise. Therefore, under anaerobic conditions SHP2+-NO must be processed by some other mechanism. In addition, biochemical results reveal that the SHP/DHC complex has NO reductase activity under anaerobic conditions. Unfortunately, this function was not proved in vivo. SHP was initially isolated from Rhodobacter sphaeroides and its structure was reported in 2000. Based upon this structure, SHP is clearly a class I cytochrome c with one axial histidine ligand to the heme iron. Unusually, however, it has an asparagine residue as the other axial heme ligand, and as such is unique among cytochromes c. For this reason it may be assumed that the asparagine plays a special role. This study reveals several potential reasons why SHP utilises asparagine as a heme ligand. Firstly, in the ferric form, asparagine 88 binds to the heme iron to prevent small molecules binding. Secondly, in the ferrous form it moves to allow oxygen to bind and form the oxy-ferrous complex, using hydrogen bonding for stability. Thirdly, using asparagine as a heme ligand creates a suitable redox potential for reduction by DHC, thus allowing NO dioxygenation.
APA, Harvard, Vancouver, ISO, and other styles
12

Russell, David D. "Design, synthesis, crystal structure and magnetic properties of novel osmium-based B-site ordered double perovskites." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10011271.

Full text
Abstract:

Transition metal oxides (TMOs) with face centered cubic arrangement of magnetic ions are composed of triangular sub-lattices. When antiferromagnetic (AFM) interactions of the same strengths between all three pathways in triangular settings are in place, spin constraints cannot be fulfilled simultaneously and the system undergoes geometric magnetic frustration (GMF). The purpose of the work presented in this thesis is to better understand the criteria for a system to undergo GMF. To achieve this, the novel B-site ordered double perovskites Ca2ScOsO6 and Ca2.2Mg0.8OsO6 were synthesized in polycrystalline form utilizing the conventional solid-state method. The crystal structure of these compounds were characterized through X-ray diffraction, and magnetic properties were explored through magnetic susceptibility measurements. Employing the spin-dimer analysis method, relative magnetic exchange interactions were calculated and modeled. These novel osmium-based B-site ordered double perovskites were then compared to isostructural compounds to study the effects of the osmium oxidation state on crystal structure and the exhibited properties.

APA, Harvard, Vancouver, ISO, and other styles
13

Parulekar, Sumedh. "A novel approach to manipulate cavity size In resorcinarenes." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001810.

Full text
APA, Harvard, Vancouver, ISO, and other styles
14

Matsumoto, Kenji. "A Novel Method of Crystal Structure Analysis Using In-Situ Diffraction Measurement of Magnetically Oriented Microcrystal Suspension." Master's thesis, Kyoto University, 2014. http://hdl.handle.net/2433/188778.

Full text
Abstract:
Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第18340号
農博第2065号
新制||農||1024(附属図書館)
学位論文||H26||N4847(農学部図書室)
31198
京都大学大学院農学研究科森林科学専攻
(主査)教授 木村 恒久, 教授 西尾 嘉之, 教授 髙野 俊幸
学位規則第4条第1項該当
APA, Harvard, Vancouver, ISO, and other styles
15

Akbar, Samina. "Novel synthesis of nanostructured platinum materials via true liquid crystal templating utilising phytantriol as a structure directing agent." Thesis, University of Reading, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582849.

Full text
Abstract:
In this investigation, nanostructured platinum materials are fabricated using a type II surfactant phytantriol as a structure directing agent. Nanoscale designing of these materials is achieved on the basis of phytantriol concentration under fixed or excess hydration conditions with or without the presence of additives; Brij-56 and 9-cis-tricosene. Phytantriol is a type II surfactant, when mixed with an aqueous solvent, it forms a diversity of lyotropic liquid crystal phases. Including a lamellar (La), inverse micellar (LII)' and inverse hexagonal (HI/), it also forms two inverse bicontinuous cubic phases (QJ/o and QJ/I) which makes this system ideal for the nanocast synthesis of platinum materials. An addition of Brij-56 induces a swelling of the QIlD phases whereas 9-cis-tricosene makes the HII phases stable at room temperature. Fabrication of nanostructured materials is carried out through the QJ/o, QJ/D , Ql, and HJ/ phases. The later three being stable in excess aqueous conditions allow the successful fabrication using thin coatings of phytantriol on a substrate surface instead of using a traditional bulk liquid crystal templating. A platinum precursor incorporated into the aqueous domains of the liquid crystal phases is deposited electrochemically or chemically (galvanic displacement reactions) utilising a conductive substrate or a less noble metal substrate, respectively. Characterisation of the fabricated materials is carried out using small angle Xray scattering and electron microscopy. Novel 3-D platinum nanowire networks of bicontinuous cubic morphology with the lattice dimensions ranging from 8.9 to 19.9 nm are fabricated using the cubic phases templates. The 3-D networks of nanowires of diameters ranging from 1.9 to 5.4 nm, fabricated through the QIP. QI/o, and Ql phases are shown to exhibit Fd3m, 14/32, and Pm3m symmetry respectively. Structural investigations reveal that the nanostructures are fabricated asymmetrically through one of the aqueous channels of the cubic phases, producing open structures. The addition of Brij-56 to the QJ/D template enables the structural tuning of these materials which is expected to change/enhance their catalytic properties. Fabrication through the HII phases with or without the presence of tricosene produces one dimensional platinum nanowires of diameters ranging from 1.7 to 2.5 nm. The platinum nanowires and nanowire networks are shown to exhibit very high specific surface area ranging from 14-40 m2 g", The nanoscale designing of these materials with excellent transport properties opens up a new general route for the nanowires and nanonetworks which have potential for use in batteries, solar cells, capacitors, and electrocatalysis
APA, Harvard, Vancouver, ISO, and other styles
16

Choi, Yeonsik. "Novel functional polymeric nanomaterials for energy harvesting applications." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/282877.

Full text
Abstract:
Polymer-based piezoelectric and triboelectric generators form the basis of well-known energy harvesting methods that are capable of transforming ambient vibrational energy into electrical energy via electrical polarization changes in a material and contact electrification, respectively. However, the low energy conversion efficiency and limited thermal stability of polymeric materials hinder practical application. While nanostructured polymers and polymer-based nanocomposites have been widely studied to overcome these limitations, the performance improvement has not been satisfactory due to limitations pertaining to long-standing problems associated with polymeric materials; such as low crystallinity of nanostructured polymers, and in the case of nanocomposites, poor dispersion and distribution of nanoparticles in the polymer matrix. In this thesis, novel functional polymeric nanomaterials, for stable and physically robust energy harvesting applications, are proposed by developing advanced nanofabrication methods. The focus is on ferroelectric polymeric nanomaterials, as this class of materials is particularly well-suited for both piezoelectric and triboelectric energy harvesting. The thesis is broadly divided into two parts. The first part focuses on Nylon-11 nanowires grown by a template-wetting method. Nylon-11 was chosen due to its reasonably good ferroelectric properties and high thermal stability, relative to more commonly studied ferroelectric polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)). However, limitations in thin-film fabrication of Nylon-11 have led to poor control over crystallinity, and thus investigation of this material for practical applications had been mostly discontinued, and its energy harvesting potential never fully realised. The work in this thesis shows that these problems can be overcome by adopting nanoporous template-wetting as a versatile tool to grow Nylon-11 nanowires with controlled crystallinity. Since the template-grown Nylon-11 nanowires exhibit a polarisation without any additional electrical poling process by exploiting the nanoconfinement effect, they have been directly incorporated into nano-piezoelectric generators, exhibiting high temperature stability and excellent fatigue performance. To further enhance the energy harvesting capability of Nylon-11 nanowires, a gas -flow assisted nano-template (GANT) infiltration method has been developed, whereby rapid crystallisation induced by gas-flow leads to the formation of the ferroelectric δʹ-phase. The well-defined crystallisation conditions resulting from the GANT method not only lead to self-polarization but also increases average crystallinity from 29 % to 38 %. δʹ-phase Nylon-11 nanowires introduced into a prototype triboelectric generator are shown to give rise to a six-fold increase in output power density as observed relative to the δʹ-phase film-based device. Interestingly, based on the accumulated understanding of the template-wetting method, Nylon-11, and energy harvesting devices, it was found that thermodynamically stable α-phase Nylon-11 nanowires are most suitable for triboelectric energy generators, but not piezoelectric generators. Notably, definitive dipole alignment of α-phase nanowires is shown to have been achieved for the first time via a novel thermally assisted nano-template infiltration (TANI) method, resulting in exceptionally strong and thermally stable spontaneous polarization, as confirmed by molecular structure simulations. The output power density of a triboelectric generator based on α-phase nanowires is shown to be enhanced by 328 % compared to a δʹ-phase nanowire-based device under the same mechanical excitation. The second part of the thesis presents recent progress on polymer-based multi-layered nanocomposites for energy harvesting applications. To solve the existing issues related to poor dispersion and distribution of nanoparticles in the polymer matrix, a dual aerosol-jet printing method has been developed and applied. As a result, outstanding dispersion and distribution. Furthermore, this method allows precise control of the various physical properties of interest, including the dielectric permittivity. The resulting nanocomposite contributes to an overall enhancement of the device capacitance, which also leads to high-performance triboelectric generators. This thesis therefore presents advances in novel functional polymeric nanomaterials for energy harvesting applications, with improved performance and thermal stability. It further offers insight regarding the long-standing issues in the field of Nylon-11, template-wetting, and polymer-based nanocomposites.
APA, Harvard, Vancouver, ISO, and other styles
17

Maurer, Joshua Ahab Grubbs Robert H. Dougherty Dennis A. "I. Structure-function analysis of the mechanosensitive channel of large conductance. : II. Design of novel magnetic materials using crystal engineering /." Diss., Pasadena, Calif. : California Institute of Technology, 2003. http://resolver.caltech.edu/CaltechETD:etd-10202002-002307.

Full text
APA, Harvard, Vancouver, ISO, and other styles
18

Koppermann, Claudia [Verfasser], Wolfgang [Gutachter] Werr, Ulrich [Gutachter] Baumann, and Karin [Gutachter] Schnetz. "Crystal Structure of the WUSCHEL Homeodomain - Description and Comparative Structural Analysis of a Novel Homeodomain Subtype / Claudia Koppermann ; Gutachter: Wolfgang Werr, Ulrich Baumann, Karin Schnetz." Köln : Universitäts- und Stadtbibliothek Köln, 2017. http://d-nb.info/1153121050/34.

Full text
APA, Harvard, Vancouver, ISO, and other styles
19

Taylor, Lesley. "Structural investigations of novel liquid crystals." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358364.

Full text
APA, Harvard, Vancouver, ISO, and other styles
20

Ewing, Sarah Jane. "Synthesis, crystal structures and properties of novel group 13 selenides." Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2803.

Full text
Abstract:
Solvothermal (and ionothermal) synthesis has been used in this work to prepare novel group 13 selenide materials. The new phases were characterised using single crystal and powder X-ray diffraction, spectroscopic methods (infrared and UV-Vis diffuse reflectance spectroscopy) and thermal analysis (thermogravimetric and elemental analysis). Other characterisation methods used include SQUID magnetometry and the measurement of optical properties. The effect of the structure directing organic molecule on the inorganic structure was investigated in this thesis, with a variety of novel materials synthesised. A family of one-dimensional chains have been prepared. The first, composed of fused four-membered rings, was found in [NH4][InSe2] (using 3,5-lutidine) and in a number of phases prepared with bicyclic superbases. The second chain-type, composed of fused four- and five-membered rings was found in [C6H16N2][Ga2-xInxSe3(Se2)] (0 < x < 2) and [C7H14N3][In2Se3(Se2)]. These chains contain a (Se2)2- perselenide bond, which was previously unreported for solvothermally prepared group 13 selenides. The third chain type, found in [C7H13N2][InSe(Se2)] and [C9H17N2][InSe(Se2)], contains fused five-membered rings. More complex one-dimensional ribbons were also prepared with superbases. Many two-dimensional layered phases have been prepared in this work. [NH4][InSe2], which contains supertetrahedral clusters, generates a second harmonic generation response. A novel phase which incorporated a transition metal into the structure has been found for [Mn(C6H14N2)3][H2O][(C6H14N2)2MnIn3(SH)2Se4.89(Se2)0.12]2. The novel hybrid gallium selenides, [Ga6Se9(C6H14N2)4][H2O] and [C6H14N2][Ga4Se6(C6H14N2)2] were also isolated. The novel layers in [C7H10N][In3Se5], contain a new octahedral building-block. A further layered material, [C8H12N][In3Se4.85(Se2)0.15] was prepared, where disorder of selenium was observed. Using weakly basic pyridine and its related methyl-substituted isomers (lutidines and picolines), a three-dimensional framework [C5H6N][In9Se14], was prepared and its ion-exchange capabilities studied. Further framework materials prepared in this work include: [enH2][NH4][In7Se12], [C6H14N2][(C6H12N2)2NaIn5Se9] and [In14Se21(Se2)3]6-. Using an ionothermal route, the known three-dimensional framework, [In33Se56]13- was prepared. The first indium selenide prepared using an ionic liquid, in this case, 1-ethyl-3-methyl-imidazolium bromide (EMIm-Br).
APA, Harvard, Vancouver, ISO, and other styles
21

Abdulmalic, Mohammad A., Azar Aliabadi, Andreas Petr, Yulia Krupskaya, Vladislav Kataev, Bernd Büchner, Torsten Hahn, Jens Kortus, and Tobias Rüffer. "An interplay between the spin density distribution and magnetic superexchange interactions: a case study of mononuclear [nBu4N]2[Cu(opooMe)] and novel asymmetric trinuclear [Cu3(opooMe)(pmdta)2](NO3)2·3MeCN." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138948.

Full text
Abstract:
Treatment of the diethyl ester of o-phenylenebis(oxamic acid) (opbaH2Et2, 1) with 5/6 equivalent of MeNH2 in abs. EtOH results in the exclusive formation of the ethyl ester of o-phenylene(N′-methyl oxamide)(oxamic acid) (opooH3EtMe, 2) in ca. 50% yield. Treatment of 2 with four equivalents of [Me4N]OH followed by the addition of Cu(ClO4)2·6H2O gave [Me4N]2[Cu(opooMe)]·H2O (3A) in ca. 80% yield. As 3A appears to be a hygroscopic solid, the related [nBu4N]+ salts [nBu4N]2[M(opooMe)]·H2O (M = Cu (3B), Ni (4)) have been synthesized. By addition of two equivalents of [Cu(pmdta)(NO3)2] to a MeCN solution of 3B the novel asymmetric trinuclear complex [Cu3(opooMe)(pmdta)2](NO3)2 (5) could be obtained in ca. 90% yield. Compounds 2, 3A, 3B, 4 and 5 have been characterized by elemental analysis and NMR/IR spectroscopy. Furthermore, the solid state structures of 3A in the form of [Me4N]2[Cu(opooMe)]·MeOH (3A′), 3B in the form of [nBu4N]2[Cu(opooMe)] (3B′), 4 in the form of [nBu4N]2[Ni(opooMe)]·1.25H2O (4′) and 5 in the form of [Cu3(opooMe)(pmdta)2] (NO3)2·3MeCN (5′), respectively, have been determined by single-crystal X-ray diffraction studies. By controlled cocrystallization, diamagnetically diluted 3B (1%) in the host lattice of 4 (99%) in the form of single crystals have been made available, allowing single crystal EPR studies to extract all components of the g-factor and the tensors of onsite CuA and transferred NA hyperfine interaction. Out of these studies the spin density distribution of the [Cu(opooMe)]2− complex fragment could be determined. The magnetic properties of 5 were studied by susceptibility measurements versus temperature. An intramolecular J parameter of −65 cm−1 has been obtained, unexpectedly, as 5 should possess two different J values due to its two different spacers between the adjacent CuII ions, namely an oxamate (C2NO3) and an oxamidate (C2N2O2) fragment. This unexpected result is explained by a summarizing discussion of the experimentally obtained EPR results (spin density distribution) of 3B, the geometries of the terminal [Cu(pmdta)]2+ fragments of 5 determined by X-ray crystallographic studies and accompanying quantum chemical calculations of the spin density distribution of the mononuclear [Cu(opooMe)]2− and of the magnetic exchange interactions of trinuclear [Cu3(opooMe)(pmdta)2]2+ complex fragments
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
APA, Harvard, Vancouver, ISO, and other styles
22

Bratu, Claudia. "Machine Learning of Crystal Formation Energies with Novel Structural Descriptors." Thesis, Linköpings universitet, Teoretisk Fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-143203.

Full text
Abstract:
To assist technology advancements, it is important to continue the search for new materials. The stability of a crystal structures is closely connected to its formation energy. By calculating the formation energies of theoretical crystal structures it is possible to find new stable materials. However, the number of possible structures are so many that traditional methods relying on quantum mechanics, such as Density Functional Theory (DFT), require too much computational time to be viable in such a project. A presented alternative to such calculations is machine learning. Machine learning is an umbrella term for algorithms that can use information gained from one set of data to predict properties of new, similar data. Feature vector representations (descriptors) are used to present data in an appropriate manner to the machine. Thus far, no combination of machine learning method and feature vector representation has been established as general and accurate enough to be of practical use for accelerating the phase diagram calculations necessary for predicting material stability. It is important that the method predicts all types of structures equally well, regardless of stability, composition, or geometrical structure. In this thesis, the performances of different feature vector representations were compared to each other. The machine learning method used was primarily Kernel Ridge Regression, implemented in Python. The training and validation were performed on two different datasets and subsets of these. The representation which consistently yielded the lowest cross-validated error was a representation using the Voronoi tessellation of the structure by Ward et. al. [Phys. Rev. B 96, 024104 (2017)]. Following up was an experimental representation called the SLATM representation presented by Huang and von Lilienfeld [arXiv:1707.04146], which is partially based on the Radial Distribution Function. The Voronoi representation achieved an MAE of 0.16 eV/atom at 3534 training set size for one of the sets, and 0.28 eV/atom at 10086 training set size for the other set. The effect of separating linear and non-linear energy contributions was evaluated using the sinusoidal and Coulomb representations. The result was that separating these improved the error for small training set sizes, but the effect diminishes as the training set size increases. The results from this thesis implicate that further work is still required for machine learning to be used effectively in the search for new materials.
APA, Harvard, Vancouver, ISO, and other styles
23

Abdulmalic, Mohammad A., Azar Aliabadi, Andreas Petr, Yulia Krupskaya, Vladislav Kataev, Bernd Büchner, Torsten Hahn, Jens Kortus, and Tobias Rüffer. "An interplay between the spin density distribution and magnetic superexchange interactions: a case study of mononuclear [nBu4N]2[Cu(opooMe)] and novel asymmetric trinuclear [Cu3(opooMe)(pmdta)2](NO3)2·3MeCN." Royal Society of Chemistry, 2012. https://tud.qucosa.de/id/qucosa%3A27795.

Full text
Abstract:
Treatment of the diethyl ester of o-phenylenebis(oxamic acid) (opbaH2Et2, 1) with 5/6 equivalent of MeNH2 in abs. EtOH results in the exclusive formation of the ethyl ester of o-phenylene(N′-methyl oxamide)(oxamic acid) (opooH3EtMe, 2) in ca. 50% yield. Treatment of 2 with four equivalents of [Me4N]OH followed by the addition of Cu(ClO4)2·6H2O gave [Me4N]2[Cu(opooMe)]·H2O (3A) in ca. 80% yield. As 3A appears to be a hygroscopic solid, the related [nBu4N]+ salts [nBu4N]2[M(opooMe)]·H2O (M = Cu (3B), Ni (4)) have been synthesized. By addition of two equivalents of [Cu(pmdta)(NO3)2] to a MeCN solution of 3B the novel asymmetric trinuclear complex [Cu3(opooMe)(pmdta)2](NO3)2 (5) could be obtained in ca. 90% yield. Compounds 2, 3A, 3B, 4 and 5 have been characterized by elemental analysis and NMR/IR spectroscopy. Furthermore, the solid state structures of 3A in the form of [Me4N]2[Cu(opooMe)]·MeOH (3A′), 3B in the form of [nBu4N]2[Cu(opooMe)] (3B′), 4 in the form of [nBu4N]2[Ni(opooMe)]·1.25H2O (4′) and 5 in the form of [Cu3(opooMe)(pmdta)2] (NO3)2·3MeCN (5′), respectively, have been determined by single-crystal X-ray diffraction studies. By controlled cocrystallization, diamagnetically diluted 3B (1%) in the host lattice of 4 (99%) in the form of single crystals have been made available, allowing single crystal EPR studies to extract all components of the g-factor and the tensors of onsite CuA and transferred NA hyperfine interaction. Out of these studies the spin density distribution of the [Cu(opooMe)]2− complex fragment could be determined. The magnetic properties of 5 were studied by susceptibility measurements versus temperature. An intramolecular J parameter of −65 cm−1 has been obtained, unexpectedly, as 5 should possess two different J values due to its two different spacers between the adjacent CuII ions, namely an oxamate (C2NO3) and an oxamidate (C2N2O2) fragment. This unexpected result is explained by a summarizing discussion of the experimentally obtained EPR results (spin density distribution) of 3B, the geometries of the terminal [Cu(pmdta)]2+ fragments of 5 determined by X-ray crystallographic studies and accompanying quantum chemical calculations of the spin density distribution of the mononuclear [Cu(opooMe)]2− and of the magnetic exchange interactions of trinuclear [Cu3(opooMe)(pmdta)2]2+ complex fragments.
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
APA, Harvard, Vancouver, ISO, and other styles
24

Edwards, Eleanor. "Novel characterisation techniques for nematic liquid crystal cells containing surface relief structures." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409717.

Full text
APA, Harvard, Vancouver, ISO, and other styles
25

Friedman, Mark Richard. "Novel thermotropic liquid crystals possessing a benzo[b]furan unit." Thesis, University of Hull, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342980.

Full text
APA, Harvard, Vancouver, ISO, and other styles
26

Khashoqji, Moayad. "Structural characterisation of novel poly-aryl compounds." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/structural-characterisation-of-novel-polyaryl-compounds(3fb1fac6-548a-4afc-8ac2-5a14885b0ba4).html.

Full text
Abstract:
Poly-aryl, also known as polyphenylene compounds are a class of dendrimer, which contain a large number of aromatic rings. They are of interest because they display restricted rotation of their stearically congested aromatic rings. These extended structures have the potential to act as precursors for even larger aromatic systems and have many applications including electronic devices, drug delivery and catalysis. A total of 23 novel poly-aryl compounds have been examined using single crystal X-ray diffraction and a number of structural patterns have emerged. Six of the compounds contain alkynes and it has been observed that their conformation is governed by a combination of conjugation between the alkyne and aryl groups and inter-molecular interactions. In the more extended poly-aryl compounds steric congestion rules out any possibility of conjugation between the rings and their conformation is governed by intra-molecular non-bonded interactions in the core of the molecules and by inter-molecular interactions in their periphery. Where possible, solution NMR measurements were carried out on the poly-aryl compounds and confirmed that the solution structures are in agreement with those obtained from individual crystal.
APA, Harvard, Vancouver, ISO, and other styles
27

Walker, Rebecca. "Synthesis and characterisation of novel liquid crystalline materials : structure-property relationships, chirality, and the twist-bend nematic phase." Thesis, University of Aberdeen, 2019. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=240697.

Full text
Abstract:
The principal aim of this Thesis is the synthesis and characterisation of a range of novel liquid crystals designed to exhibit the twist-bend nematic phase (NTB), in order to enhance our understanding of the relationships between molecular structure and the observation of NTB behaviour. Moreover, the inclusion of chiral fragments allowed the effects of molecular chirality on the structure of the NTB phase, specifically the chiral twist-bend nematic phase, N*TB, to be studied. In Chapter 3, a series of non-symmetric odd-membered liquid crystal dimers are prepared and the terminal chain length m is varied. A change in the local molecular structure from intercalated to bilayer is seen on increasing m, but this has no apparent effect on the stability of both the nematic and twist-bend nematic phases, which show a regular dependence on m. A novel twist-bend smectic phase is reported. Chapter 4 investigates the effects of branching this terminal chain on phase behaviour. It is evident that in dimers with a shorter spacer, branching destabilises the N and NTB phases while stabilising smectic behaviour, but in longer homologues smectic behaviour is also destabilised. Chapter 5 explores the effect of molecular bulk on phase behaviour, specifically the stability of the NTB phase, by the incorporation of a pyrene moiety. This group supresses crystallisation such that stable, low temperature NTB phases are formed despite the bulky group. Chapters 6 and 7 study the inclusion of chiral moieties in bent-shaped, odd-membered dimers: specifically, 2-methylbutyl, 1-methylheptyl (6) and lactic esters (7). New examples of the rarely observed chiral twist-bend nematic phase are seen. Phase behaviour is investigated and compared to achiral and racemic analogues. Chapter 8 describes the mesogenic behaviour of molecular complexes assembled by hydrogen bonding between both achiral and chiral stilbazole-based and benzoic acid-based fragments. A selection of the complexes exhibit the N(*)TB phase despite only one or neither component being mesogenic.
APA, Harvard, Vancouver, ISO, and other styles
28

García, Castelló Javier. "A Novel Approach to Label-Free Biosensors Based on Photonic Bandgap Structures." Doctoral thesis, Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/35398.

Full text
Abstract:
The necessity of using extremely high sensitivity biosensors in certain research areas has remarkably increased during the last two decades. Optical structures, where light is used to transduce biochemical interactions into optical signals, are a very interesting approach for the development of this type of biosensors. Within optical sensors, photonic integrated architectures are probably the most promising platform to develop novel lab-on-a-chip devices. Such planar structures exhibit an extremely high sensitivity, a significantly reduced footprint and a high multiplexing potential for sensing applications. Furthermore, their compatibility with CMOS processes and materials, such as silicon, opens the route to mass production, thus reducing drastically the cost of the final devices. Optical sensors achieve their specificity and label-free operation by means of a proper chemical functionalization of their surfaces. The selective attachment of the receptors allows the detection of the target analytes within a complex matrix. This PhD Thesis is focused on the development of label-free photonic integrated sensors in which the detection is based on the interaction of the target analytes with the evanescent field that travels along the structures. Herein, we studied several photonic structures for sensing purposes, such as photonic crystals and ring resonators. Photonic crystals, where their periodicity provokes the appearance of multiple back and forth reflections, exhibits the so-called slow-light phenomenon that allows an increase of the interaction between the light and the target matter. On the other hand, the circulating nature of the resonant modes in a ring resonator offers a multiple interaction with the matter near the structure, providing a longer effective length. We have also proposed a novel approach for the interrogation of photonic bandgap sensing structures where simply the output power needs to measured, contrary to current approaches based on the spectral interrogation of the photonic structures. This novel technique consists on measuring the overlap between a broadband source and the band edge from a SOI-based corrugated waveguide, so that we can determine indirectly its spectral position in real-time. Since there is no need to employ tunable equipment, we obtain a lighter, simpler and a cost-effective platform, as well as a real-time observation of the molecular interactions. The experimental demonstration with antibody detection measurements has shown the potential of this technique for sensing purposes
García Castelló, J. (2014). A Novel Approach to Label-Free Biosensors Based on Photonic Bandgap Structures [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/35398
TESIS
APA, Harvard, Vancouver, ISO, and other styles
29

Pilotti, Massimino U. "Activation of B-H bonds at metal centres : syntheses and crystal structures of some novel metallacarborane complexes." Thesis, University of Bristol, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481420.

Full text
APA, Harvard, Vancouver, ISO, and other styles
30

Romir, Johannes [Verfasser]. "Expression and Purification of Arabidopsis Two-Component System Proteins, Diffraction Experiments with Crystals of Amide Synthetase NovL and Structure Determination of Human MAP Kinase p38 in Complex with Inhibitors / Johannes Romir." München : Verlag Dr. Hut, 2012. http://d-nb.info/1022535234/34.

Full text
APA, Harvard, Vancouver, ISO, and other styles
31

Donovan, Michael James. "Structural characterisation and analysis of two plant lectins : Scilla campanulata fetuin-binding protein (2.8AÌŠ), a novel two-domain member of the monocot mannose-binding superfamily & the legume lectin Lens culinaris in multiple crystal forms and in co." Thesis, Liverpool John Moores University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439054.

Full text
APA, Harvard, Vancouver, ISO, and other styles
32

Al-Bloushi, Mohammed. "Synthesis and Characterization of Novel Quaternary Thioaluminogermanates." Thesis, 2013. http://hdl.handle.net/10754/293347.

Full text
Abstract:
Metal chalcogenides form an important class of inorganic materials, which include several technologically important applications. The design of metal chlcogenides is of technological interest and has encouraged recent research into moderate temperature solid-state synthetic methods for the single crystal growth of new materials. The aim of this project is the investigation and development of synthetic methodology for the synthesis of novel metal chlcogenides. The new inorganic compounds of the type “M(AlS2)(GeS2)” (M = Na and K) are new metal-chalcogenides, synthesized by the classical solid state approach. The characterization of these compounds was carried out by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Single crystal and powder X-ray diffraction, solid state Nuclear Magnetic Resonance (NMR), Ultraviolet-visible (UV-VIS), Infrared (IR) and Raman spectroscopy. These theses study the synthesis of metal chalcogenides through the use of standard chemical techniques. The systematic studies demonstrate the effect of the reactants ratio and reaction temperature on the synthesis and growth of the single crystals. Metal chalcogenides have several potential applications in gas separation, ion exchange, environmental remediation, and energy storage. Especially, the ion exchange materials have found possible applications in waste-water treatment, water softening, metal separation, and production of high purity water.
APA, Harvard, Vancouver, ISO, and other styles
33

Wang, Liang-Jhih, and 王良誌. "1D Photonic Crystal Tunable Nanocavity Lasers with Novel Nanoclamp Structure." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/3wvq59.

Full text
Abstract:
碩士
國立交通大學
光電工程研究所
107
In this thesis, based on the large wavelength response per percentage strain (7.8 nm) of 1D photonic crystal (PhC) tunable nanocavity laser, we further propose and setup novel nanoclamps nearby both sides of 1D PhCs. It can create a non-ideal elastic region to produce non-uniform structural deformation distribution under an applied linear stress. Owing to the different deformation between the clamped and unclamped regions, the wavelength response of the device can be significantly enhanced. At first, via the mechanical/optical numerical simulation based on finite-element method, we confirm the non-uniform deformation of 1D PhC nanocavity with nanoclamp under different strains, as well as the corresponding tunable properties of the resonance mode inside. By further discussing the optical properties of 1D PhC nanocavities with different nanoclamp parameters, the enhancing mechanism is initially clarified and used for establishing simple design rules. Based on our previous nanofabrication techniques, we further optimize the process to meet the requirements of nanoclamp structure, which realizes this design and improves its yielding rate. The devices not only show single mode lasing operations with low lasing thresholds in measurements, but also show good matchings with the simulation results. The experimental wavelength responses can be enhanced to 10–12 nm under different nanoclamp parameters. In addition, we also theoretically propose an optimized design with wavelength response as large as 15.9 nm. On the other hand, the nanoclamp is also applied on 1D PhC waveguide without defect design both in simulation and experiment. Via the non-uniform deformation caused by nanoclamp under stress, a nanocavity with high quality factor can be created. This implies that an on-demanded and reproducible nanocavity laser could be achieved by this strain-induced waveguide-nanocavity conversion. We believe our proposed novel mechanical/optical hybrid design in this study would provide interesting and highly potential possibilities for optical strain sensors and nanolasers in flexible photonic integrated circuits.
APA, Harvard, Vancouver, ISO, and other styles
34

Hwu, Rong-Jyh, and 胡榮治. "The Chemical Synthesis, Crystal Structure and Characterization of Some Novel Ternary Metal Nitrides." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/63027263301975302309.

Full text
Abstract:
碩士
國立交通大學
應用化學系
83
The syntesis of novel ternary transition metal nitrides A3M3N (A ＝Co, Ni；M＝Mo, W) has been attempted by ammonolysis of corresponding AMO4 oxide precursors at temperature of 600℃ to 800℃. X-ray diffraction indicated that Co3Mo3N (M＝Mo, W) crystallize in cubic structure with space group Fd3.cflex.m (No. 227) and lattice constants ao＝11.020(1) Angstrom and 11.010(1) Angstrom for M＝Mo and W, respectively. In addition, Rietveld refinement also indicated that Co3M3N (M＝Mo, W) are isostructural with Fe3Mo3N (.eta.-Fe3Mo3C, E93 type). On the other hand, the two new nickel-containing nitrides, Ni3M3N (M＝ Mo, W) have been indexed as an orthorhonbic cell with a ＝6.635(2), b＝6.668(4) and c＝6.573(3) Angstrom for M＝Mo and a cubic cell with ao＝6.641(3) Angstrom for M＝W, respectively. The determination of crystal structure of these two nitrides are in progress. On the other hand, the X-ray photoelectron core spectra indicated that nitrogen does form metal nitrides for the title compounds based on the chemical shift of the N1s bindingrgy. The A3M3N (A＝Co, Ni；M＝Mo, W) nitrides exhibited typical metallic behavior with room temperature resistivity of 2.0∼9.0 m.OMEGA.-cm in the temperature range of 300∼10K. Temperature- dependent magnetic susceptibility (.chi. VS. T) data showed that the four title metal nitrides exhibited Curie- Weiss type paramagnetism at temperature above approximately 120K with deviation of .chi.-T from linearity at low temperature. Furthermore, the magnetization curves of the title metal nitrides were also investigated at 50K and 5K, respectively. We have found that magnetic hysteresis, indicating possible presence of ferromagnetism, was observed in the Co3M3N (M＝Mo, W) compounds at 5K only, whereas no such phenomenon was observed in the Ni3Mo3N (M＝Mo, W) compounds.
APA, Harvard, Vancouver, ISO, and other styles
35

Chen, Sheng-Chia, and 陳勝嘉. "Crystal structure of Dlcaligenes faecalis DA1 D-aminoacylase defines a novel subset of amidohydrolases." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/34245313600087742961.

Full text
Abstract:
碩士
國立陽明大學
生物化學研究所
90
D-aminoacylase is an attractive candidate for commercial production of D-amino acids through its catalysis in the hydrolysis of N-acyl-D-amino acids. Here we report the first D-aminoacylase structure, solved by the Se-SAD method, and refined at 1.5 Å resolution. The protein comprises a catalytic “TIM” (βα)8 barrel and a β domain with the highest structural similarity to urease and cytosine deaminase, suggesting that D-aminoacylases indeed belong to the recently identified amidohydrolase superfamily. Unexpectedly, the enzyme binds two zinc ions with widely different affinities, although only the tightly bound zinc is required for activity. One zinc is tightly coordinated by Cys 96, His 220, and His 250, while the other is loosely ligated by His 67, His 69, and Cys 96. Therefore, D-aminoacylase is a mononuclear enzyme but containing a binuclear active site, and then defined a novel subset. The preferred substrate was modeled into a hydrophobic pocket, revealing the substrate specificity.
APA, Harvard, Vancouver, ISO, and other styles
36

Li, Cheng-Wen, and 李正文. "A Novel Structure and Application of Optical Logic Gate with Liquid Crystal Spatial Light Modulators." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/18366462162661795751.

Full text
Abstract:
碩士
元智大學
電機工程學系
95
In this thesis, optical logic gate is proposed by a novel structure and its application. Two liquid crystal spatial light modulators (LCSLMs) are used to construct the optical logic gate system. This optical logic gate with XOR operation is used to achieve both image encoding and decoding operations. This system is composed of two sets of LCSLMs, which is aligned by microscope and stuck with adhesive. It will take us less time to set up the system and to perform strict alignment in experiment. On the other hand, it can reduce the influence of vibration in optical experiment. We investigate the binary image encryption and decryption with Jones matrix in this system. In image encryption, we obtained the random binary image after encoding process. Furthermore, the decoded image is obtained by coupling of the encrypted image and random key. Finally, we utilize MSE and PSNR to evaluate the decrypted image under different random key. The simulation and experimental results are presented to investigate the performance of our system.
APA, Harvard, Vancouver, ISO, and other styles
37

Yeh, Shih-Fang, and 葉蒔芳. "In situ Hydrothermal Syntheses, Crystal Structure, and Properties of a Novel Zinc(II) Tetrazolate Coordination Polymers." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/90623425344773288800.

Full text
Abstract:
碩士
國立臺灣海洋大學
生物科技研究所
95
The [2+3] cycloaddition reactions of cyano with NaN3 through “the in situ ligand hydrothermal syntheses system” afford the ZnN3[5-(3-pyridyl)tetrazolato]; ZnN3(3-ptz). This compound is a 3D networks crystal which contains the tetrazole functional group. By the X-ray diffraction analysis, the crystal crystallizes in the monoclinic system, space group C2/c, with a = 20.4737(5) Å, b = 7.7035(2) Å, c = 14.6938(4) Å, β = 130.0540(10)°. This is a novel crystal structure, we will study the properties of physical and biological. The tetrazole functional group has found a wide range of application in many area. In medicinal chemistry as a bioisoteres for a carboxylic acid group, bioisosteres are substituents or groups with similar physical or chemical properties that impart similar biological properties to a chemical compound. Compare the toxicity of bioisoteres and similar compound with ZnN3(3-ptz). We find that ZnN3(3-ptz) and bis(nicotiato)zinc all have cell toxicity in cell and bacteria. The gram-positive bacteria is more significant in the antibacterial effect, the gram-negative bacteria, mainly attributes to the bilayer of cell membrane in gram-negative bacteria, cause limiting the passage of small molecules across the outer barrier.
APA, Harvard, Vancouver, ISO, and other styles
38

Pei-YuChuang and 莊霈于. "The novel topological insulator materials of crystal and electronic structure studied by angle-resolved photoemission spectroscopy." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/63b94d.

Full text
Abstract:
博士
國立成功大學
物理學系
106
Three-dimensional topological insulator has led to intense research owing to the potential applications of these materials in the field of spintronics and quantum computing. TIs are insulating materials in the bulk, which host metallic surface states in the energy gap with a Dirac-cone-like dispersion. These states are protected by time-reversal symmetry that show spin-momentum locking and leads to suppression of the electron backscattering by defects. The corresponding topological invariants dictate that there must be an odd number of such states intersecting the Fermi level between each pair of surface time-reversal invariant momenta. The bismuth-chalchogenide family of topological insulators are just one of these so-called topological surface states creating a single Dirac cone in the Brillouin zone centre. More importantly, additional pairs of two-dimensional, almost parabolic states emerge in the vicinity of the bulk conduction band, which develop large Rashba-type splitting. Since large spin-orbit coupling is prerequisite for a material to exhibit topologically protected states, bismuth is a primary candidate and bismuth bilayers have become under intense study. Which are now regarded as a prototype of an elemental 2D TIs. Recently, investigating step edges of a Bi(111) surface have aimed to prepare bismuth bilayers by using molecular beam epitaxy or exfoliation. In this thesis, the electronic band structure of topological insulator materials has been systematically studied by angel-resolved photoemission spectroscopy. Chapter 1 introduces the research background for topological insulators. Chapter 2 describes the principle of photoemission spectroscopy and x-ray absorption spectroscopy for electronic and crystal structure. Chapter 3 introduces synchrotron radiation for XPS, ARPES, and XAS end station at Taiwan Light Source and SPring-8. In Chapter 4, we present a simple and controllable approach, which is based on exposing c single crystal thin film to a flux of atomic hydrogen. Angle-resolved photoemission spectroscopy (ARPES) and other surface sensitive techniques such as x-ray photoemission spectroscopy (XPS), low energy electron diffraction (LEED). Bi2Se3 thin films were transferred into ultra-high vacuum prepare chamber base pressure around 1E-9 torr and decapping protect layer of Se by thermal heated. ARPES measurements indicate a well contrasted sharp TIs surface state. Atomic hydrogen was generated by a thermal cracker source, during the operation of atom source, the hydrogen partial pressure in the chamber was PH2 is 1.2E-7 torr. For the quantification of the exposure of the sample, the Langmuir (L) units (1L=1E10-6 torr) in the following, which is proportional to the amount of hydrogen atoms interacting with the sample that was kept at room temperature. It was obtained electronic band structure of single bismuth bi layer (111) terminated Bi2Se3 (0001) surface that the TIs surface state of the system features the Dirac point at about 0.4 eV below the Fermi level, as in a Rashba type splitting. In chapter 5, we report the directly observed key role of an anti-site defect with tuning the Fermi level (EF) in Bi2Te3 topological insulators. Tuning the Fermi level (EF) in Bi2Te3 topological-insulator (TI) films is demonstrated on controlling the temperature of growth with molecular-beam epitaxy (MBE). Angle-resolved photoemission spectra (ARPES) reveal that EF of Bi2Te3 thin films shifts systematically with the growth temperature (Tg). The key role that a Bi-on-Te(1) (BiTe1) antisite defect plays in the electronic structure is identified through extended x-ray-absorption fine-structure (EXAFS) spectra at the Bi L3-edge. Calculations of electronic structure support the results of fitting the EXAFS, indicating that the variation of EF is due to the formation and suppression of BiTe1 that is tunable with the growth temperature. Our findings provide not only insight into the correlation between the defect structure and electronic properties but also a simple route to control the intrinsic topological surface states, which could be useful for applications in TI-based advanced electronic and spintronic devices. At last chapter 6 summarizes the conclusion and suggests the future research topics.
APA, Harvard, Vancouver, ISO, and other styles
39

Ettaki, Zacharia Nabil. "Developing Novel Methods to Identify RNA-Associated Mechanisms for Inheritance." Thesis, 2020. http://hdl.handle.net/1805/24500.

Full text
Abstract:
Indiana University-Purdue University Indianapolis (IUPUI)
Animals depend on inheriting non-genetic information early in life to grow and develop naturally. This inherited, non-genetic information was previously thought to be limited to DNA modifications and DNA binding proteins. But recent studies have expanded our understanding of inheritance to include RNA and RNA binding proteins. We currently lack methods to identify and enrich for RNA binding proteins that might be involved in providing non-genetic information from mother to daughter cells. Others have developed a method using modified enzyme tags to pulse-label proteins with small molecule fluorescent ligands and follow these proteins as they are inherited by cells. Here I characterized and tested the application of a fluorescent small molecule targeting antibody to enrich for these labeled proteins. I first tested the ability of this antibody to bind to fluorescent ligand-labeled enzymes. I determined that the antibody can efficiently bind to at least one of the labeled enzymes. Second, I determined crystallization conditions for the ligand binding antibody fragment. This thesis sets the stage for structure determination and to test whether this antibody can work in vivo to enrich for RNA binding proteins involved in the delivery of non-genetic information to cells.
APA, Harvard, Vancouver, ISO, and other styles
40

KAO, YUNG-YUAN, and 高永原. "Novel Design of the Electrode Structure and ItsDriving Scheme to Improve Response Time of aTunable Liquid Crystal Lens." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/94258932768896968243.

Full text
Abstract:
碩士
中原大學
機械工程研究所
96
A new method here is proposed for improving the response time of tunable liquid-crystal lens (LC lens) with the concentric-ring electrode pattern through a suitable driving scheme. Compared with conventional liquid-crystal lens, the new structure of liquid-crystal lens in this work is composed with only two ITO glasses and each of them is designed the concentric-ring pattern. Thus, one can control the orientation of liquid-crystal director via the four-terminal switch on the electrode patterns. Moreover, it exhibits abilities to eliminate the disclination line, formed by the director dismatch during driving the LC lens, and to reduce the rise time of LC lens to less than one second. It shows an application potential instead of the optical lens with fixed focus length or the conventional LC lens with single circular-hole electrode pattern.
APA, Harvard, Vancouver, ISO, and other styles
41

Vicente, V., A. Fruchier, M. Taillefer, C. Coombes-Chamelet, Ian J. Scowen, F. Plenat, and H.-J. Cristeau. "Synthesis and structural studies (H-1, C-13, P-31 NMR and X-ray) of new C-bonded cyclotriphosphazenes with heterocyclic substituents from novel phosphinic acid derivatives." 2004. http://hdl.handle.net/10454/3552.

Full text
Abstract:
No
Three new C-bonded cyclotriphosphazenes, [N3P3(2-thienyl)6], 2, [N3P3(3-thienyl)6], 4, and [N3P3(3,3-bithienyl-2,2-ylene)3], 6, have been prepared by two new synthetic procedures and are the first examples of non-spiro and trispirocyclotriphosphazene derivatives composed of thiophene and 3,3-dithiophene substituents, respectively. Their 1H, 13C and 31P NMR parameters are given. The solid state structures of 2, 4 and 6 have been determined by X-ray crystallography.
APA, Harvard, Vancouver, ISO, and other styles
42

Maurer, Joshua Ahab. "I. Structure-Function Analysis of the Mechanosensitive Channel of Large Conductance. II. Design of Novel Magnetic Materials using Crystal Engineering." Thesis, 2003. https://thesis.library.caltech.edu/4188/11/Thesis.pdf.

Full text
Abstract:

The work presented here encompasses two distinct areas, with the first section addressing structure-function relationships in the mechanosensitive channel of large conductance (MscL) from bacteria. A high-throughput fluorescent screening technique has been developed for the E. coli homologue of MscL. This technique has been applied to a large library of random E. coli MscL mutations to provide insights into channel function. Additionally, attempts have been made to characterize the functionally important regions of MscL and comparisons have been made between the E. coli and M. tuberculosis homologues of MscL.

The second section addresses the design of novel magnetic materials. The guanidinium sulfonate "Ward lattice" from crystal engineering has been used to develop a new family of frustrated magnetic materials.

APA, Harvard, Vancouver, ISO, and other styles
43

Lin, Hsien-Ya, and 林仙雅. "Crystal Structure of RpfF and crystallization of RpfB from Stenotrophomonous maltophilia : Potential Target Proteins for Novel Antibiotics Development via Quorum Quenching." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/d3bqjp.

Full text
Abstract:
碩士
國立中興大學
生物化學研究所
98
Stenotrophomonas maltophilia has emerged as a critical noncosomial opportunistic pathogen in the last few years. It is resistant to many clinically useful antibiotics; hence, new ways of combating this bacterium are essential. Diffusible signal factor (DSF) dependent quorum sensing is a major mechanism of virulence induction in S. maltophilia, with RpfF playing a key role in DSF biosynthesis. Inhibiting S. maltophilia RpfF (SmRpfF) function via small molecule interference may constitute a new way of treating S. maltophilia infection. SmRpfF has been overexpressed in Escherichia coli, purified and crystallized using hanging-drop vapour-diffusion method. The crystals belong to the tetragonal space group P41212 containing three protein molecules per asymmetric unit, with unit-cell parameters a = b = 148.51, c = 122.82 Å, and were diffracted to a resolution of 2.25 Å. Our results indicate that SmRpfF belongs to the enoyl-CoA hydratase / enoyl-CoA isomerase family, but with some distinct features; the acyl-CoA substrate entrance is blocked to a great extent by re-orientated C-terminal
APA, Harvard, Vancouver, ISO, and other styles
44

"Studying novel material properties using synchrotron-based soft x-ray spectroscopy." Thesis, 2015. http://hdl.handle.net/10388/ETD-2015-07-2134.

Full text
Abstract:
This thesis is centred around the study materials with novel electronic properties, including transition metals interacting with semiconductors and unique molecular systems. The idea of advancing modern computing is the basis for motivating the work in that the projects all have potential to be used in novel applications that would impact the efficiency and/or execution of current technology. We have studied two variations of transition metals as they appear in materials and two molecular systems. As for the transition metals interacting with semiconductors, we first discuss transition metal atoms introduced as impurities to a semiconductor lattice, and second, we discuss transition metal oxides that are naturally semiconducting. We have used a number of experimental and theoretical techniques to better understand these groups of materials. Materials prepared through high quality synthesis techniques were studied using x-ray spectroscopy made possible by synchrotron light sources. Computational software then allowed for the experiments to be interpreted by comparing them to the simulations. In the study of transition metals as impurities, we chose the Co:MoS2 system because MoS2 has had promising results with other transition metal dopants. We examined the electronic structure for two purposes: (1) to determine the local bonding environment and locations of the cobalt atoms in order to better understand the behaviour of Co as an impurity; and (2) the overall band gap of the system so that we could evaluate the system’s potential for use in applications. Experimental results combined with our theoretical simulations led us to conclude that the samples available were all metallic, and at low concentrations cobalt atoms were able to substitute directly into the MoS2 lattice. An examination of copper (II) oxide allowed us to investigate the ability to tune the band gap of a known semiconductor through a synthesis process that applied axial pressure to the sample. For a collection of samples prepared at different pressures, x-ray spectroscopy methods showed an increasing band gap with increasing synthesis pressure, a result that is most encouraging for the field of band gap engineering. Using soft x-ray spectroscopy to examine the conduction and valence bands of the two molecular systems, the potassium-doped hydrocarbons and Li2RuO3, was important for drawing conclusions about the materials’ composition and behaviour. Results showed the introduction of new states at the lower edge of the conduction band of K:phenanthrene, a possible reason for its low-temperature superconductivity. Li2RuO3’s electronic structure was examined and compared to calculations performed by collaborators.
APA, Harvard, Vancouver, ISO, and other styles
45

Hu, Chi-Sheng, and 胡啟苼. "X-ray Crystal Structure of Novel Cyclic-di-GMP Binding Receptor Acetohydroxy Acid Synthase Isozyme III (AHAS III) Regulatory Subunit IlvH and the Negative-staining EM Study of AHAS III Holoenzyme Complex IlvI/IlvH." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/x3j4br.

Full text
Abstract:
碩士
國立中興大學
生物化學研究所
106
C-di-GMP (cyclic dimeric guanosine 3’,5’-monophosphate) is a ubiquitous bacterial secondary messenger that is involved in the regulation of many critical processes. C-di-GMP can reduce motility by downregulating flagellar expression or interfering with flagellar motor function. AHAS III is involved in synthesizing branched chain amino acids (BCAAs) such as isoleucine, leucine, valine and is composed of two kinds of subunit: a large subunit IlvI (61kDa), which contains all the catalytic residues of the enzyme, and a small subunit IlvH (17kDa), which has a regulatory function. The small subunit is necessary for feedback inhibition by valine. Previous research showed that c-di-GMP could also bind with IlvH but no further data is available. Since bioinformatics search found no canonical c-di-GMP binding motifs in IlvH, it thus may represent another novel c-di-GMP binding domain. Furthermore, BCAAs are synthesized by plants, algae, fungi and bacteria, but not by animal. Thus, the enzymes of the BCAA biosynthetic pathway are potential targets in the development of herbicides, fungicides and antimicrobial compounds. Here we focus on understanding how c-di-GMP binds with IlvH and on the structural studies of AHAS III holoenzyme complex IlvH/IlvI by negative-staining EM. We confirm that c-di-GMP binds IlvH with a moderate strong KD (10.8µM affinity) by using Isothermal Titration Calorimetry and Differential Scanning Fluorimetry. Before crystallization we have screened over 500 different conditions in order to find the optimum buffer for IlvH-c-di-GMP crystal formation. We were able to get some crystals that diffracted up to 2.5Å. Unfortunately, we couldn’t find c-di-GMP density map, which is possibly due to the significant conformational change when bound with c-di-GMP. Then we dock c-di-GMP to the solved IlvH structure and found that R109、R84 can potencially bind with c-di-GMP by hydrogen bond. We used c-di-GMP to titrate with the muntant IlvH R109Aand IlvH R84A, and found that these two residues had reduced binding affinity with c-di-GMP. Furthermore, I also truncated the C terminal of IlvH and also used c-di-GMP to titrate with the IlvH_N domain, found that there was no binding by using Isothermal Titration Calorimetry. Thus, c-di-GMP seems to bind with the IlvH¬¬¬_C domain. On the other hand, I also overexpressed and purified IlvI for mixing with IlvH and found that they form a heterotetramer in solution by gel-filtration analysis. Finally, we solved a low resolution structure of AHAS III holoenzyme complex IlvI/IlvH by negative staining EM.
APA, Harvard, Vancouver, ISO, and other styles
46

Chang, Chi-Tung, and 張吉東. "Fabrication of Novel Photonic Crystal Laser Structures." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/17164360168771166111.

Full text
Abstract:
碩士
國立交通大學
光電工程系所
93
In this thesis, first we introduce the principles of photonic crystal structures and our research motive. The history and developments of photonic crystal lasers are also described and discussed. In the fabrication of photonic crystals, in order to combine the laser cavity and photonic crystal structure, we use electron-beam lithography, dry etching, and undercut process to form a membrane photonic crystal laser. We also introduce photonic crystal lasers with asymmetric structure. In order to obtain better characteristics of photonic crystal lasers, the wafer bonding technology is introduced to integrate MQWs wafer with different uncompatible wafers. We utilize the direct bonding method and glue bonding method to integrate the 1550nm long-wavelength MQWs with DBR wafer or sapphire. The effect factors of bonding process and choice of bonding materials are discussed. At last, we measure the photoluminescence spectra of our membrane devices and bonding samples.
APA, Harvard, Vancouver, ISO, and other styles
47

Maluleka, Marole Maria. "Synthesis, biological evaluation and molecular docking studies of novel indole- and benzofuran-chalcone and benzofuran-quinazoline hybrids as anticancer agents." Thesis, 2019. http://hdl.handle.net/10500/25821.

Full text
Abstract:
Text in English
Specially prepared 2-amino-5-bromo-3-iodoacetophenone and 5-bromo-2-hydroxy-3 iodoacetophenone were subjected to Claisen-Schmidt aldol condensation with benzaldehyde derivatives followed by sequential and/or one-pot palladium catalyzed Sonogashira cross coupling and heteroannulation of the 3-alkynylated intermediates to afford indole-chalcones and benzofuran-chalcones, respectively. The indole-chalcones derivatives were, in turn, subjected to trifluoroacetic anhydride in tetrahydrofuran under reflux to afford the corresponding 3-trifluoroacetyl substituted indole-chalcone derivatives. The coupling constant values (Jtrans) of about 16.0 Hz for the chalcone derivatives corresponding to the vinylic protons confirmed the trans geometry of the α,β-unsaturated carbonyl framework in all the cases. Their trans geometry of the chalcone derivatives was further confirmed by single crystal X-ray diffraction (XRD) analyses. Further structural elaboration of the ambident electrophilic α,β unsaturated carbonyl (chalcone) moiety of the indole-chalcones and the analogous benzofuran chalcones with 2-aminothiophenol afforded novel benzothiezapine-appended indole and benzofuran hybrids, respectively. Sonogashira cross-coupling of 5-bromo-2-hydroxy-3 iodoacetophenone with terminal acetylenes followed by heteroannulation of the intermediate 3-alkynylated 5-bromo-2-hydroxyacetophenones afforded the corresponding 7-acetyl-2-aryl-5-bromobenzofurans in a single-pot operation. The oximes derived from the 7-acetyl–substituted 2-aryl-5-bromobenzofurans were subjected to Beckmann rearrangement with triflic acid in acetonitrile under reflux. We isolated the corresponding 7-amino-2-aryl-5 bromobenzofuran derivatives formed from hydrolysis in situ of the intermediate 7-acetamide 2-aryl-5-bromobenzofurans. Amino-dechlorination of the 4-chloroquinazoline derivatives with the 7-aminobenzofurans afforded novel benzofuran 4-aminoquinazoline hybrids. The prepared compounds were characterized using a combination of nuclear magnetic resonance (1H-NMR & 13C-NMR including 19F-NMR), infrared (IR) and mass spectroscopic techniques complemented with single crystal X-ray diffraction (XRD) analyses and/or density functional (DFT) method. The benzofuran-chalcone 203a–y derivatives were evaluated for anti-growth effect against the breast cancer (MCF-7) cell line by the MTT cell viability assay. Their mode of cancer cell death (apoptosis versus necrosis) was detected by Annexin V-Cy3 SYTOX staining and caspase-3 activation. The most cytotoxic compounds 203i and 203o were also evaluated for potential to inhibit tubulin polymerization and/or epidermal growth factor receptor-tyrosine kinase (EGFR-TK) phosphorylation. The experimental results were complemented with theoretical data from molecular docking into ATP binding site of the EGFR and colchicine binding site of tubulin, respectively. The benzofuran–4-aminoquinazoline hybrids 215a–j, on the other hand, were evaluated for antiproliferative propeties in vitro against the human lung cancer (A549), epithelial colorectal adenocarcinoma (Caco-2) and hepatocellular carcinoma (C3A) cell lines. The benzofuran-aminoquinazoline hybrids were also evaluated for potential to induce apoptosis and for their capability to inhibit EGFR-TK phosphorylation complemented with molecular docking (in silico) into the ATP binding site of EGFR. Mechanistic studies demonstrated that the benzofuran-appended aminoquinazoline hybrids 215d and 215j induced apoptosis via activation of caspase-3 pathway. Moreover, compounds 215d and 215j exhibited significant and moderate inhibitory effects against EGFR (IC50 = 29.3 nM and 61.5 nM, respectively) when compared to Gefitinib (IC50 = 33.1 nM). Molecular docking of compounds 215 into EGFR-TK active site suggested that they bind to the region of EGFR like Gefitinib does.
Chemistry
D. Phil. (Chemistry)
APA, Harvard, Vancouver, ISO, and other styles
48

Rengarajan, Rajesh. "Optical properties of novel structures of colloidal crystals." Thesis, 2004. http://hdl.handle.net/1911/18808.

Full text
Abstract:
Photonic crystals are materials having a periodicity in their refractive index. This results in the inhibition of select frequencies of light from propagating within the crystal causing the formation of a gap in the photonic band structure. Analogous to semiconductors, the presence of a photonic band gap makes these materials tremendously promising for a new revolution in the technology industry. Their periodic nature make them ideal for two-dimensional lithographic fabrication. However self assembly methods with colloids offer the most promising route to fabricating three-dimensional structures, so as to affect the confinement of light in all directions. The work presented in this thesis strives to advance the understanding of colloidal crystals to ultimately facilitate the construction of real, working, commercial devices. We probe the optical properties of such colloidal crystals and describe techniques to engineer them into novel structures, such as crystals of hollow spherical shells, to enhance the performance of the photonic band gap. We examine novel architectures like colloidal photonic superlattices to generate propagation modes within the band gap and show that such structures can be fabricated to have uses as filters and optical resonators. We investigate incorporating colloidal crystal structures into organic light-emitting devices to improve device performance by spatially modifying the light output. Finally, as it is critical to fabricate high quality devices approaching the accuracy obtained by lithography, we conduct a systematic and quantitative study of the nature of defects in these colloidal crystals and correlate structural defects during fabrication to altered optical properties.
APA, Harvard, Vancouver, ISO, and other styles
49

Lai, Hui-Chun, and 賴薈君. "Syntheses, Crystal Structures and Properties of Novel Mixed Metal Phosphate and Aluminum Phosphite." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/70164818456052693910.

Full text
APA, Harvard, Vancouver, ISO, and other styles
50

Chan, Yu-Hin-Benny, and 陳宇軒. "Synthesis, Crystal Structures and Properties of Novel Mixed Metal Scandium Phosphites and Zinc Phosphate." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/u72ay3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the bibliographies on the topic 'Novel Crystal Structure' for other source types:
Journal articles
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography