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Application Of Expert Systems In Analytical And Environmental Chemistry, Qiwei Zhu
Application Of Expert Systems In Analytical And Environmental Chemistry, Qiwei Zhu
Digitized Theses
Expert systems are knowledge based computer programs that offer the possibility of combining theories with heuristic expertise, and are therefore capable of solving domain-specific problems. However, little is known about how human knowledge can be effectively and precisely transferred into computer programs. In addition, the lack of a seamless man-machine interface also causes reduced general acceptance of expert systems. In this thesis, the process of knowledge acquisition and the role of the user interface in expert systems are investigated. Results are presented that describe the development of two prototypic expert systems: SPILLexpert and GSMSdiagnosis.;The knowledge domain matrix (KDM) is an …
Aspects Of Reactions Of Sulfonyl Compounds With Nucleophiles, Manjinder Singh Gill
Aspects Of Reactions Of Sulfonyl Compounds With Nucleophiles, Manjinder Singh Gill
Digitized Theses
This thesis describes four topics in organic sulfur chemistry involving reactions of sulfonyl compounds with nucleophiles. In the first chapter the reactions of aromatic sulfonyl chlorides with amines in aqueous media were studied. The observed pH-yield profiles pointed strongly to the involvement at high pH of third-order processes leading to the sulfonamides. A new term {dollar}(k\sb{lcub}\rm NOH{rcub}){dollar} was introduced in the rate expression (eq 9) and the calculated pH-yield profiles from eq 10 gave a good agreement with experimental data. The increased value of rate constants with alkyl chain size of the amine, suggested aggregation of reactants due to hydrophobic …
Ftir Spectroscopic Studies Of Adsorbates On Metal Surfaces, Rita Violet Kasza
Ftir Spectroscopic Studies Of Adsorbates On Metal Surfaces, Rita Violet Kasza
Digitized Theses
Fourier transform infrared (FTIR) spectroscopic studies of adsorbates on metal surfaces have been carried out using FTIR reflection-absorption spectroscopy, synchotron radiation FTIR and time-resolved FTIR, along with Auger electron spectroscopy, low energy electron diffraction, thermal desorption spectroscopy, nuclear reaction analysis and work function change. For water on hex and (1 x 1) Pt(100), clustering takes place readily at low temperature from the lowest coverages, and a small number of large clusters tend to form. On Pt(100) containing Si impurity, clusters are initially nucleated at impurity sites and tend to be smaller and more numerous. For H{dollar}\sb2{dollar}O/Al(100) at T {dollar}<{dollar} 130 K, a distribution of relatively small clusters exists. At coverages under 0.35 ML on Ni(110), water adsorbs monomerically at 85-180 K, and the H{dollar}\sb2{dollar}O wagging and rocking modes can be observed in the far IR.;On both stepped Ni(760) and Ni(110), the saturation coverage for the first chemisorbed layer is 0.5 ML (ML = {dollar}1.15\times10\sp{lcub}15{rcub}{dollar} molecules cm{dollar}\sp{lcub}-2{rcub}){dollar} and no FTIR activity (1000-4000 cm{dollar}\sp{lcub}-1{rcub}){dollar} is observed until the coverage exceeds 0.5 ML. Less water exists in the A{dollar}\sb1{dollar} desorption state on Ni(760) compared with D{dollar}\sb2{dollar}O/Ni(110). At temperatures above 398 K, water is observed to autocatalytically dissociate on clean Ni(760), forming H{dollar}\sb2{dollar}(g) and O(ads). Ni(760) appears to be much more reactive than Ni(110), resulting in a significantly higher reaction probability. A (2 x 1)-O phase is formed upon completion of the reaction, corresponding to an absolute oxygen coverage of 0.3-0.4 ML depending on the reaction temperature.;A fast time-resolved Fourier transform spectroscopy (FTRFTS) system has been developed for obtaining reflection IR data on surfaces with microsecond time resolution. Laser induced thermal desorption is a suitable method for modulating the CO coverage on a Pt surface. Conversion of linearly bonded to bridge bonded CO can be observed in thermal transients, suggesting that the species are not in equilibrium at room temperature. The FTRFTS system has been used for the first time to obtain FTIR-RAS spectra of CO on Pt(111).
Core Level Spectroscopy Studies Of Organosilicon Compounds, Jianzhang Xiong
Core Level Spectroscopy Studies Of Organosilicon Compounds, Jianzhang Xiong
Digitized Theses
Si core level X-ray Absorption Fine Structures (XAFS) spectroscopy has been used to study, in the gas phase, the structure and bonding of a series of highly symmetric organosilicon compounds, Si(CH{dollar}\sb3)\sb4{dollar} (TMS), Si{dollar}\rm\sb2(CH\sb3)\sb6{dollar} (HMDS), Ge (Si(CH{dollar}\sb3)\sb3\rbrack\sb4{dollar} (GESI4), Si (Ge(CH{dollar}\sb3)\sb3\rbrack\sb4{dollar} (SIGE4), and Si (Si(CH{dollar}\sb3)\sb3\rbrack\sb4{dollar} (SISI4), which can be used as model compounds for silicon-germanium electronic materials.;The Si K- and L{dollar}\sb{lcub}2,3{rcub}{dollar}-edge X-ray absorption near edge structure (XANES) of HMDS, GESI4 SIGE4 and SISI4 have been recorded with synchrotron radiation and calculated by the multiple-scattering (MS) X{dollar}\alpha{dollar} method. It is found that there is a significant difference in the absorption coefficient in the …
1,4-Biradicals In Intermolecular Photocycloaddition Reactions Of Cyclic Enones With Alkenes, And, 1,4-Biradicals In Intramolecular Photocycloaddition Reactions Of Cyclic Enones With Alkenes, David Jack Maradyn
Digitized Theses
The irradiation of cyclic enones with ultraviolet light in the presence of alkenes results in the formation of cyclobutane adducts possessing head-to-head and/or head-to-tail regiochemistry. The long-accepted Corey-de Mayo mechanism predicts that the regiochemistry of the cyclobutane adducts is controlled by the relative orientation of the enone and alkene in an exciplex intermediate. Weedon and co-workers have demonstrated that partitioning of 1,4-biradical intermediates between starting material and cyclobutane products controls the product regiochemistry in the intermolecular photocycloaddition reactions of 2-cyclopentenones with alkenes.;These earlier results have been extended. The 1,4-biradical intermediates formed in the photocycloaddition reactions of 2-cyclohexenone with alkenes, in …
Interactions Of Oxygen, Hydrogen And Water With Zr(0001) And Zr(1010), Bing Li
Interactions Of Oxygen, Hydrogen And Water With Zr(0001) And Zr(1010), Bing Li
Digitized Theses
The interaction of oxygen, hydrogen and water with Zr(0001) and Zr(1010) has been studied by surface science techniques. A hopping model of the diffusion of adsorbed species from a surface into the bulk has been formulated and solved mathematically. Applying this model to our AES results on oxygen dissolution, we obtained the Arrhenius expressions for diffusion as: 0.115exp({dollar}-{dollar}44.45 kcal/RT) cm{dollar}\rm\sp2s\sp{lcub}-1{rcub}{dollar} along {dollar}\langle0001\rangle,{dollar} and 1.07exp({dollar}-{dollar}46.18 kcal/RT) cm{dollar}\rm\sp2s\sp{lcub}-1{rcub}{dollar} along {dollar}\langle10\=10\rangle.{dollar};Oxide dissolution was studied by measuring the change of the oxide thickness at a series of temperatures for a constant initial coverage prepared at a fixed and low temperature. The rate-controlling step in …
Interactions Of Silver And Gold Complexes With Sulphide Minerals: A Surface Study, Michael John Scaini
Interactions Of Silver And Gold Complexes With Sulphide Minerals: A Surface Study, Michael John Scaini
Digitized Theses
This thesis examines the interactions of the aqueous species {dollar}\rm Ag\sp+,\ AgCl\sb{lcub}x{rcub}\sp{lcub}1-x{rcub},\ AuCl\sb4\sp-{dollar} and AuSH with the surfaces of PbS, (Zn,Fe)S and FeS{dollar}\sb2{dollar} with the aim of better understanding the role that sulphide minerals play in concentrating precious metals from solution. Through the use of surface (XPS, AES, SEM) and conventional (AAS, IC, electrochemistry) analytical techniques, insight into mineral modification, metal chemistry and morphology, alloy composition and solution chemistry is obtained.;Reactions of Ag{dollar}\sp+{dollar} and the three minerals resulted in the presence of Ag{dollar}\sb2{dollar}S and Ag(0) being observed on all mineral surfaces, in a 2 step process where Ag{dollar}\sb2{dollar}S, then Ag(0) …
Vuv Laser/Time-Of-Flight Mass Spectroscopy: Valence To Ion-Pair States Transitions Of Brcl And Cl(2), Peng Wang
Vuv Laser/Time-Of-Flight Mass Spectroscopy: Valence To Ion-Pair States Transitions Of Brcl And Cl(2), Peng Wang
Digitized Theses
This thesis describes a newly built vacuum ultraviolet (VUV) laser/time-of-flight (TOF) mass spectrometer system in great detail. The theoretical background behind the techniques is also provided. Tunable, coherent, and monochromatic VUV "laser" radiation was generated by the nonlinear optical technique of two-photon resonantly enhanced four-wave difference-mixing (FWDM) in Kr gas. The Frequency resolution of the recorded spectra is estimated to be {dollar}\leq{dollar}0.2 cm{dollar}\sp{lcub}-1{rcub}.{dollar} The mass resolution, m/{dollar}\Delta{dollar}m, of the linear TOF mass spectrometer {dollar}\geq{dollar}500, which was sufficient to obtain single isotopomer data.;With this instrument, vibrationally and rotationally resolved spectra of the {dollar}E0\sp+{dollar} (v{dollar}\sp\prime=173-203){dollar} ion-pair state {dollar}\leftarrow X0\sp+{dollar} (v{dollar}\sp{lcub}\prime\prime{rcub}=0){dollar} ground state …
Diagnostic Expert Systems In Instrumental Analysis, Hai Du
Diagnostic Expert Systems In Instrumental Analysis, Hai Du
Digitized Theses
The acquisition of knowledge is a key phase in the implementation of expert systems yet represents a significant bottleneck. An explanation-based method was applied to knowledge compilation in a GC diagnostic system. A package of macros for Microsoft Excel, MATRIX, was then developed to enable domain experts to build rule-based knowledge bases for expert systems. The MATRIX macros can be used as domain-oriented knowledge acquisition tools that are specialized in coding knowledge concerning the diagnosis of faults in analytical instruments. These knowledge acquisition tools do not require formulation of any certainty factors to resolve conflicts and enable experts in analytical …
Variable Energy Photoelectron Spectra Of Metal Carbonyls, Yongfeng Hu
Variable Energy Photoelectron Spectra Of Metal Carbonyls, Yongfeng Hu
Digitized Theses
High resolution gas phase photoelectron spectra of transition metal carbonyls, W(CO){dollar}\sb6,{dollar} Os(CO){dollar}\sb4{dollar}L (L = CO, PMe{dollar}\sb3),{dollar} CpM(CO){dollar}\sb3{dollar} (M = Mn, Re), CpFe(CO){dollar}\sb2{dollar}I, and Re(CO){dollar}\sb5{dollar}X (X = Re(CO){dollar}\sb5,{dollar} Cl, Br, and I) are reported. The advantages of monochromatized synchrotron radiation for studying the electronic structure of organometallic molecules are demonstrated. All the levels of these metal carbonyls from valence to inner-valence and core levels at high resolution can be studied in one spectrum.;For the core levels, vibrational fine structure is clearly resolved for the first time on the core of W 4f levels of W(CO){dollar}\sb6,{dollar} and this structure can be rationalized …
Spectroscopy Of Unstable Molecules, Hafed Ashur Bascal
Spectroscopy Of Unstable Molecules, Hafed Ashur Bascal
Digitized Theses
The {dollar}\rm B\sp2\Sigma\sp{lcub}+{rcub}{dollar} ion-pair excited states for the unstable group IIB metal monohalide radicals have acquired eminence as the upper levels for the potentially important blue/green lasers. In this work, the metal monohalide radicals were produced by exciting a corona excited electrical discharge in a supersonic gas expansion. The ion-pair-valence {dollar}\rm B\sp2\Sigma\sp{lcub}+{rcub}\gets X\sp2\Sigma\sp{lcub}+{rcub}{dollar} transitions for several of these species were recorded by the method of laser induced fluorescence excitation spectroscopy. For HgCl the resultant spectra recorded over the 368-267nm range reveal an extensive vibrationally and isotopically resolved structure due to transitions between {dollar}\rm X\sp2\Sigma\sp{lcub}+{rcub}\ (2\ge v\sp{lcub}\prime\prime{rcub}\ge0){dollar} and {dollar}\rm B\sp2\Sigma\sp{lcub}+{rcub}\ (75\ge …
Astroglial Insulin-Like Growth Factor Binding Proteins: Regulation Of Synthesis And Relationship To Cell Growth, Sheri Lynn Bradshaw
Astroglial Insulin-Like Growth Factor Binding Proteins: Regulation Of Synthesis And Relationship To Cell Growth, Sheri Lynn Bradshaw
Digitized Theses
The insulin-like growth factors (IGFs) regulate the growth and differentiation of a wide variety of tissues, including the brain. The biologic actions of IGFs are modulated by a family of six IGF binding proteins (IGFBPs), which, like IGFs, are synthesized as paracrine factors. We hypothesized that the IGFBPs synthesized by astroglial cells, are regulated by growth factors produced in the developing brain, and modulate the growth of these cells. Primary astroglial cells synthesized IGFBP-2 and IGFBP-3 which were upregulated in a dose dependent manner by IGF-I, IGF-II, and very high concentrations of insulin, suggesting that the growth factors regulate their …
Multicomponent Interdiffusion In Micellar Solutions And Microemulsions, Ling Hao
Multicomponent Interdiffusion In Micellar Solutions And Microemulsions, Ling Hao
Digitized Theses
This thesis focuses on multicomponent interdiffusion in micellar solutions and microemulsions. The Taylor dispersion technique is used to measure ternary diffusion coefficients for aqueous micellar solutions of: sodium dodecylsulfate (SDS)/NaCl; SDS/alcohol solubilizates; and sodium cholate (SC)/alcohol solubilizates. Ternary diffusion coefficients are also reported for water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/n-heptane and water/2-propanol/n-hexane water-in-oil microemulsions. The results include cross-diffusion coefficients, which provide new insights into the interactions between diffusing surfactants and solubilizates.;The diffusion coefficient of SDS in aqueous salt solutions determined by Taylor dispersion is found to be smaller than the diffusion coefficient of the micelles indicated by the popular quasi-elastic light scattering …