• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 470
  • 224
  • 88
  • 61
  • 58
  • 27
  • 22
  • 15
  • 10
  • 10
  • 6
  • 5
  • 5
  • 4
  • 4
  • Tagged with
  • 1217
  • 224
  • 141
  • 111
  • 108
  • 83
  • 75
  • 67
  • 60
  • 59
  • 57
  • 56
  • 55
  • 53
  • 53
  • 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.
21

Experimental investigation of the thermo-mechanical response of Intumescent Mat Material

Kim, Hyungjun January 2000 (has links)
No description available.
22

Revisiting New Babylon : the making and unmaking of a nomadic myth

McGowan, Jérémie Michael January 2011 (has links)
This thesis revisits Constant’s New Babylon (about 1956-1974). Turning to theories of primitivism and, in particular, Christopher L. Miller’s critical reading of ‘the nomad’ found in Gilles Deleuze’s and Félix Guattari’s A Thousand Plateaus (1980), I use previously published and unconsidered archival materials alike to demonstrate the importance of Romani to Constant’s original work and thinking on New Babylon. Positioning these materials against a selection of dominant claims, reference points and images now circulating in established New Babylon and Situationist International scholarship, I argue that Constant’s daily life and artistic practice, together with key moments in the development and public display of his project, are framed by references to, yearnings for and personal dealings with Romani, both real and imagined. Questioning contemporary theorisations of nomadism through a consideration of who travels and why, I advocate for a greater awareness of and sensitivity to the historical conditions that produce particular forms of movement. New Babylon and Romani are inextricably intertwined: to forget the one is to misunderstand, and misrepresent, the other.
23

Syntheses and Characterization of 4-(Di(2-pyridymethyl)-aminomethyl)imidazolyl Metal (Zn, Cu, Ni, Fe) Complexes

Lin, Jing-Hung 11 August 2005 (has links)
Late transition metal complexes bearing nitrogen-containing ligands have many applications in biotechnology or industrial catalysis. Imidazole is one of the most common biofunctional ligands to play critical roles in meta1loenzymes, since the imidazole moiety of the histidyl residues often constitutes all or part of the binding sites of various transition metal ions. We use the newly synthesized tetradentate ligand containing the imidazolyl and pyridyl functional group to react with zinc, copper, nickel, and iron ions in order to carry out biomimetic studies. We have obtained two crystal structures via different methods of crystallization. One of them is a mononuclear complex while the other is a polymeric structure. The polymeric structure has demonstrated the spontaneous deprotonation on the imidazolyl nitrogen on binding to the metal ion followed by the intermolecular self-assembly process.We believe that the imidazolate -bridged complexes undergo the pH-dependent interconversions between mononuclear (protonated ligand) and self-assembled oligomer (deprotonated ligand). In addition, we have measured the titration curves of the tetradentate ligand and its corresponding metal complexes to determine the preferential binding sites at varying pH. From the titration processes, we got the protonation constant of ligand and stability constants of its corresponding metal complexes.
24

Benjamin Constant et la construction du régime parlementaire (1814-1830) / Benjamin Constant and the making of parlementiarism (1814-1830)

Neveu, Romain 21 November 2014 (has links)
Théoricien du régime républicain de 1795 à 1810, Benjamin Constant se doit d'adapter son système institutionnel à la Restauration des Bourbons en 1814. Cependant son attachement à la monarchie constitutionnelle, illustrée par sa participation à la rédaction de l'Acte additionnel durant les Cent-jours n'entraîne pas une renonciation à sa pensée libérale.Malgré cette fidélité apparente aux principes libéraux qu'il défendait déjà en 1800 au sein du Tribunat, et qui entraîna son expulsion en 1802, la pratique de la monarchie constitutionnelle le confronte à différents problèmes auxquels ses écrits théoriques ne répondent pas; ainsi, le pouvoir royal constitue-t-il véritablement un pouvoir neutre, ou son pouvoir de nomination des ministres ne l'entraîne-t-il pas à intervenir directement dans les affaires du pays? De plus, Une fois élu député, en 1819, c'est aussi l'importance des droits de la minorité qu'il doit défendre, notamment envers la majorité ultra de la Chambre «retrouvée» de 1824, et c'est donc l'importance du règlement de l'assemblée, seul cadre légal auquel est astreint la majorité, qu'il va développer.Mais la monarchie constitutionnelle suppose aussi la responsabilité des gouvernants, celle des députés par la réélection, mais aussi celle des ministres, élément central du régime parlementaire. Cette responsabilité ministérielle oscillant entre procédure pénale spéciale et justification politique, comme l'illustre l'acte d'accusation envers Villèle auquel participe Constant en 1827. Mais le contrôle des gouvernants s'effectue aussi indirectement par l'opinion publique dont les journaux sont le relais. Leur développement exponentiel au début du XIXème siècle, expliquant l'importance accordée par Constant aux différentes législations sur la presse intervenant de 1814 à 1830.En tant que journaliste, homme politique et député, Constant participe directement à l'élaboration du gouvernement représentatif qui va devenir le régime parlementaire sous la Monarchie de Juillet, mais cette confrontation à la vie politique l'entraîne-t-elle à abandonner certains éléments de sa doctrine, ou tout au moins à faire évoluer certains éléments pour les adapter à la pratique? De plus, son intervention est-elle réellement décisive dans la mise en place des différents éléments du régime parlementaire ou les désaccords avec les autres libéraux ou avec les doctrinaires l'entraînent-ils à la marge?C'est donc au travers de l'ensemble de son œuvre théorique, ainsi que de ses différents articles de journaux mais aussi par sa participation aux débats de la Chambre des députés et enfin par l'analyse des différentes théories s'affrontant sur le sens de la Charte et la pratique de la Monarchie constitutionnelle, que le rôle de Constant dans la construction du régime parlementaire pourra être analysé. / The Restoration represents the beginnings of the parliamentary in France. This form of government based on the political responsibility of the ministry before the assemblies. .It is built by the practice more than the application of a preconceived theoretical system. Through the interventions of Benjamin Constant in the press and at the House of Representatives we can study the implementation of Parliamentary in France since 1814 to 1830. But the purpose of Constant during this area is also the safeguarding of rights.
25

A Novel Constant Volume System for Determining Transport Properties in Polymeric Membranes

Leszczynski, Peter Jr. 05 July 2023 (has links)
Membrane gas separation became an industrial reality in the late 1970s with Monsanto's first commercial asymmetric hollow fiber membrane modules. Innovations in membrane separations result from new materials that exhibit an improved permeability and are more selective than their predecessors, with materials commonly compared to the "upper bound line." Accurate determination of the three transport properties which characterize a membrane, permeability (P), diffusivity (D), and solubility (S), is thus of great interest to exceed the current upper bound line. Also, proper characterization of membrane materials enables enhancing current commercial membrane processes or allows for new applications. All three transport properties, P, S, and D, can be determined using a single dynamic gas permeation experiment in a constant volume (CV) system, commonly called the time-lag method. This work presents the next-generation CV system that utilizes the two-tank volume concept, namely a reference volume and a working volume. Compared to the previous iteration, the pressure in the reference volume can be reduced to the anticipated pressure in the working volume after initiating the gas permeation experiment. This allows monitoring of the pressure decay in the working volume (i.e., gas permeation into the membranes) using a high-resolution differential pressure transducer (DPT) right after initiating the experiment. The new system's operation is demonstrated by simultaneous monitoring of the upstream pressure decay and the downstream pressure rise during the time-lag experiments using a polyphenylene oxide (PPO) membrane. The values determined using the pressure decay method are compared to those determined using the downstream method to identify any limitations still present in the current iteration of the CV system. To set a reliable benchmark value to compare against, the downstream receiver was redesigned, and an optimal configuration was identified, which was associated with negligible resistance to gas accumulation and, thus, a minor error in the experimental time lag downstream from the membrane. Furthermore, a temperature enclosure was built to minimize errors caused by the constant temperature assumption during the time lag analysis. Additionally, the temperature-controlled enclosure allows for transport properties temperature dependence to be quantified by determining the activation energy of permeability, diffusion, and the enthalpy of solution for a given gas/polymer system.
26

Rationalization of potentiometric procedures for the precise determination of formation and pH

Jones, C. F. January 1987 (has links)
No description available.
27

Electrokinetic and electrostatic properties of highly charged colloids in low-dielectric media

Gillespie, David January 2016 (has links)
No description available.
28

pH and ionic strength effects on the binding constant between N-PAHs and humic acid

gao, shu-min 29 August 2007 (has links)
This study investigates the influence of ionic strength on the binding constant (KDOC) between benzo(h)quinoline (BHQ) and LHA by using fluorescence quenching method. Being a basic polycyclic aromatic hydrocarbon, BHQ is the dominated solute as the solution¡¦s pH value is higher than BHQ¡¦s pKb. In contrast, BHQ+ is the major species as the solution¡¦s pH value is lower than BHQ¡¦s pKb. In a salty neutral or basic LHA solution, the cation will bind with the acidic functional groups of LHA, then the conformation of LHA would be coiled up to be small in size. Due to that, leading to the decrease of the corresponding BHQ¡¦s KDOC. Furthermore, the charge density of cation is an important factor in control of the variation of BHQ¡¦s KDOC. The lower charge density of cation is, the less BHQ¡¦s KDOC varied. Besides, SO4 2- may suppress the binding affinity between Na+ and the acidic function groups of LHA, so that lower variation of BHQ¡¦s KDOC was observed than that of Cl- in a Na+ contained LHA solution. In an acidic solution, cation will also bind with the acidic functional groups of LHA, leading to the decrease of the binding sites of BHQ+ on LHA and the corresponding BHQ+¡¦s KDOC. Besides, Mg2+ could provide more binding sites for the acidic functional groups of LHA than Na+, so that the variation of BHQ+¡¦s KDOC with Mg2+ addition is higher than that with Na+ addition.
29

Operators which are constant with respect to slant Toeplitz operators

Chen, Chien-chou 04 July 2006 (has links)
Let H be a separable Hilbert space and {e_n : n belong to Z} be an orthonormal basis in H. A bounded operator T is called the slant Toeplitz operator if <T ej , ei> =c2i−j , where c_n is the n-th Fourier series of a bounded Lebesgue measurable function on the unit circle T = {z belong to C : |z| = 1}. It has been shown [7] that T* is an isometry if and only if |fi(z)|^2 +|fi(−z)|^2 = 2 a.e. on T and if this is the case and fi belong to C(T), then either T is unitarily equivalent to a shift or to the direct sum of a shift and a rank one unitary, with infinite multiplicity (for the shift part, that is). Moreover, with some additional assumption on the smoothness and the zeros of fi, T* is similar to either the constant multiple of a shift or to the constant multiple of the direct sum of a shift and a rank one unitary, with infinite multiplicity. On the other hand, according to the terminologies in [10], an operator A that is constant with respect to a shift S if AS = SA and A S = SA . Therefore, in this article, we will study the operators that is constant with respect to T , i.e., bounded operator A satisfying AT = T A and A T = T A .
30

The study of the binding constant between polycyclic aromatic hydrocarbons and humic substances

Tseng, Huang-kai 27 July 2009 (has links)
Polycyclic aromatic hydrocarbons (PAHs) are in general characterized by high toxicity, persistance, and bio-accumulation in environment. It is important to understand the transport and fate of PAHs in environment. In aquatic environment, PAHs are easily bound with dissolved organic matter (DOM), such as humic substance, and KDOC is usually used in denoting the binding constant. Previously, many investigations focused on the binding of a single PAH to DOM. However, few researches considered the competition effect on the binding of multiple PAHs to DOM. This study therefore explored the competition between the binary PAHs, pyrene and phenanthrene, in binding with humic substances. No significant competition effect in KDOC could be observed between these two compounds with LHA (Leonardite Humic Acid) because of the relatively large variation in KDOC determination. Humic substances from different sources might have different properties. Several characteristic indicators of humic substances were used to interprete the variations of KDOC of pyrene and phenanthrene, such as elemental ratio, total acidity, functional group content, etc. Negative correlations of O/C and phenolic group content to the KDOC of pyrene and phenanthrene were observed (p<0.05). In contrast, positive correlation of aromaticity and £`280 of humic substance to the KDOC of pyrene and phenanthrene were observed (p<0.05). Therefore, the contents of phenolic and aromatic groups of humic substance are essential factors in determining their binding constants with PAHs.

Page generated in 0.068 seconds