Modern non-destructive approaches for quality control in manufacturing often rely on X-ray computed tomography to measure even difficult-to-reach features. Unfortunately, such measurements require hundreds or thousands of calibrated X-ray projections, which is a time-consuming process and may cause bottlenecks. In the recent state-of-the-art research, tens and hundreds of projections are still required. In this thesis, we examine the radiography physics, technologies, and ex- isting solutions, and we propose a novel approach for non-destructive dimensional measurements from a limited number of projections. Instead of relying on com- puted tomography, we formulate the measurements as a minimization problem in which we compare our parametric model to reference radiographs. We propose the whole dimensional measurements pipeline, including object parametrizations, material calibrations, simulations, and hierarchical optimizations. We fully im- plemented the method and evaluated its accuracy and repeatability using real radiographs of real physical objects. We achieved accuracy in the range of tens or hundreds of micrometers, which is almost comparable to industrial computed tomography, but we only used two or three reference radiographs. These results are significant for industrial quality control. Acquiring...

Hydrolysis products of aluminum that exist in aqueous solutions play an important role in controlling the fate and transport of contaminants and are also used for coagulants to purification of wastewater streams. Adsorption of contaminants such as heavy metals and organics are widely recognized, but the molecular level understanding of the mechanism of action has not been clearly defined. In this research we present the crystallization, structural characterization and chemical characterization of three novel Keggin-type aluminum polycations including ((Al(IDA)H2O)2(Al30O8(OH)60(H2O)22)(2,6 NDS)4(SO4)2Cl4(H2O)40) (Al32-IDA),[(Cu(H2O)2(µ2-OH)2)2(Al2(µ4-O)8(Al28(µ2-OH)50(µ3-OH)6(H2O)26(2,6-NDS)9(H2O)52]-(CuAl30) and [(Zn(NTA)H2O)2(Al(NTA)(µ2-OH)2)2(Al30(µ2-OH)54(µ3-OH)6(µ4-O)8(H2O)20(2,6-NDS)5(H2O)64]-(ZnAl32) where IDA = iminodiacetic acid, NTA- Nitrilotriacetic acid, and 2,6 NDS = 2,6 napthalene disulfonate. These compounds are the first ever reported Keggin-type aluminum species that have been functionalized with organics and heavy metal cations. Structural characterization of these compounds was done by means of single crystal X-ray diffraction along with FTIR, TGA, SEM/EDS and PXRD techniques for chemical characterization. This study provides more insight into the coagulation process and can be employed in developing optimized coagulants for enhanced water purification.

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The reaction between the lithium enolate of cyclohexanone and phenyl vinyl sulfoxide resulted in the formation of the novel bicyclooctanol sulfoxides 215-217 and the monoalkylated sulfoxide 218. The effects of variation in reaction time, temperature and concentration were studied. Under optimal conditions (10 minutes, -10°C and 0.085 M) the ratio of the bicyclooctanol sulfoxides 215-217 (75% yield) to the monoalkylated sulfoxide 218 was 95:5. The bicyclooctanol sulfoxides 215-217 were characterised as the sulfone derivatives, bicyclooctanol sulfones 219 and 220. X-ray crystal structures were used to determine the relative stereochemistry of the bicyclooctanol sulfoxides 215-217 and the bicyclooctanol sulfones 219 and 220. Bicyclo[4.2.0]octano-1-ol formation was determined to occur via an ionic mechanism. Mechanistic studies were carried out using variations in reaction lighting and reaction solvent, conducting the reaction in the presence of a radical trap and quenching the reaction with a deuterium label. The role of the counterion was determined to be important in the formation of the bicyclooctanol sulfoxides 215-217. Sequestering lithium ions with HMPA and substituting lithium with potassium favoured alkylation. Substituting the lithium enolate of cyclohexanone with the dimethylaluminium enolate of cyclohexanone resulted in a different distribution of the bicyclooctanol sulfoxides 215-217 and the formation of bicyclooctanol sulfoxide 243. Transition states to account for these differences have been proposed. The stability of the bicyclooctanol sulfoxides under conditions of acid, base and heating was studied. Thermal ring opening of the bicyclooctanol sulfoxides 215 and 216 to the monoalkylated sulfoxides 218A and 218B respectively occurred with retention of the configuration at sulfur. The relative stereochemistry of the individual bicyclooctanol sulfoxides 215-217 was considered to account for the observed stability in each case. The reaction between the lithium enolate of cyclohexanone and (R)-(+)-p-tolyl vinyl sulfoxide 193 gave the bicyclooctanol tolyl sulfoxides 246, 251 and 252 and the monoalkylated tolyl sulfoxide 247. This showed that both bond rotation in the side chain of the intermediate and epimerisation at sulfur occurred in the bicyclo[4.2.0]octan-1-ol forming process. The presence of the sulfoxide functionality in phenyl vinyl sulfoxide was determined to be crucial to the formation of bicyclo[4.2.0]octan-1-ols. In the reaction with the lithium enolate of cyclohexanone, phenyl vinyl sulfide gave no reaction, phenyl vinyl sulfone gave the bicyclic disulfones 260-265, ethyl acrylate gave the diesters 266-268 and diphenylvinylphosphine oxide gave the phosphine oxide 269. The cyclobutanol 270 and the ketone 271 were the products resulting from the reaction between the reaction between the lithium enolate of acetophenone and phenyl vinyl sulfoxide. This demonstrated potential scope for the cyclisation process using both cyclic and acyclic ketones.

The staling of baked products remains a significant cause of economic loss due to the loss of enjoyment seen as crumb firming occurs. The aims of the current project have been to investigate the stability of amylases in bakery formulations. In addition, the impact of partial hydrolysis products of starch on staling is investigated. Specific assays were used to measure ƒÑ-amylase and ƒÒ-amylase, in the presence of the other potentially interfering activity. ƒÑ-Amylase activity levels appeared to gradually increase during the proofing stages and then to decline upon heating of the dough. However, the activity remaining in the final baked loaf was readily measurable indicating that not all of the enzyme had been inactivated. Free and total ƒÒ-amylase activities were also measured and most was found to be in the free form. ƒÒ-Amylase was unstable with only relatively low activities remaining in the final baked loaf. It appears that of the two amylolytic enzymes, ƒÑ-a mylase is sufficiently stable that it may exert some impact on the crumb characteristics in the freshly baked product and during subsequent storage. In order to assess the likelihood that amylolysis is of significance to crumb characteristics, HPLC was used to analyse aqueous extracts for sugars. Commercial flours were found to contain low levels of sugars with maltose being the predominant sugar present. A number of commercial breads were also analysed and the composition found to vary between the different samples. Typically maltose was present at higher levels than the other sugars. When experimental loaves were analysed, the patterns showed that other sugars declined during proofing whereas maltose remained at readily measurable levels. Upon baking and subsequent storage the amounts of maltose increased. These results are consistent with the findings that some amylolytic activity remains in the baked product. In the third phase of this study, a potential means of investigating the role of particular carb ohydrates in product textures and staling rates was examined. The approach of spray drying was used to prepare microencapsulated maltodextrin. The encapsulating agents used were based upon rice starch and guar galactomannan. When these microcapsules were incorporated into the breadmaking formulation and baked, it appeared that softer crumb characteristics were achieved. The data also indicates an effect of delay in the staling rates. In a preliminary evaluation of the potential of two X-ray scattering methods, it was found that both techniques appear useful. The differences seen for samples of bread crumb analysed at various stages of storage did not show large differences in the intensity patterns. Of the two approaches, small angle analysis (SAXS) appears to show greater potential for application in ongoing studies of staling. In conclusion, cereal grain ƒÑ-amylase may be more stable during breadmaking than previously thought. There appears to be an increase in the level of some low molecular weight sugars in the final, baked product. Microencapsulation may offer a useful technique for the study of the role of specific carbohydrates during baking and storage of breads.

The dinuclear cyclometallated gold(I) complex [Au2(μ-2-C6F4PPh2)2] was prepared in high yield from the reaction of 2-LiC6F4PPh2 with either [AuBr(AsPh3)] or [AuCl(tht)], and from the reaction of 2-Me3SnC6F4PPh2 with [AuCl(tht)]. The digold(I) complex undergoes oxidative addition reactions with halogens to give the metal-metal bonded dihalodigold(II) complexes [Au2IIX2(μ-2-C6F4PPh2)2] (X = Cl, Br, I), which on warming or exposure to light, isomerise to give the heterovalent gold(I)-gold(III) species [XAu(µ-2-C6F4PPh2)(κ2-2-C6F4PPh2)AuX] containing a four-membered cyclometallated ring on a gold(III) centre. Unlike its protio analogue, [Au2(μ-2-C6F4PPh2)2] did not undergo oxidative addition of methyl iodide or dibenzoyl peroxide. The dihalodigold(II) [Au2IIX2(μ-2-C6F4PPh2)2] and gold(I)-gold(III) compounds [XAu(µ-2-C6F4PPh2)(κ2-2-C6F4PPh2)AuX] (X = Cl, Br) are further oxidised by halogens to give the digold(III) species [Au2X4(μ-2-C6F4PPh2)2] and [X3Au(μ-2-C6F4PPh2)(κ2-2-C6F4PPh2)AuX], respectively. The complexes [Au2X4(μ-2-C6F4PPh2)2] are reduced to the dihalodigold(II) complexes in the presence of one equivalent of zinc powder; further addition of zinc gave the parent digold(I) dimer. Treatment of [Au2IICl2(μ-2-C6F4PPh2)2] and [ClAu(µ-2-C6F4PPh2)(κ2-2-C6F4PPh2)AuCl] with an excess of silver nitrate, benzoate, acetate, trifluoroacetate or triflate gave the corresponding oxyanion complexes. Slow crystallisation of the di(benzoato)digold(II) complex from dichloromethane and methanol gave the parent digold(I) complex derived by reductive elimination. The di(triflato)digold(II) complex behaved similarly, although in this case the novel gold(I) tetramer [Au4(μ-2-C6F4PPh2)4] was formed together with the dimer. Two closely related gold complexes containing the chelating κ2(C,O) phosphine oxide ligand, 2-C6F4P(O)PPh2, were isolated from the reaction of [ClAu(µ-2-C6F4PPh2)(κ2-2-C6F4PPh2)AuCl] with an excess of silver nitrate. The reaction of [Au2IICl2(μ-2-C6F4PPh2)2] with two equivalents of potassium trifluoroethoxide failed to give the corresponding digold(II) bis(alkoxo) complex; instead, reduction took place to form the digold(I) dimer [Au2(μ-2-C6F4PPh2)2]. Treatment of a solution of the di(benzoato)digold(II) complex with C6F5Li gave the pentafluorophenyl complex [Au2(C6F5)2(μ-2-C6F4PPh2)2] which, when heated in toluene, rearranged to the gold(I)-gold(III) complex [(C6F5)Au(µ-2-C6F4PPh2)(κ2-2-C6F4PPh2)Au(C6F5)], analogous to the behaviour of the dihalodigold(II) complexes. The heterovalent, gold(I)-gold(III) dimethyl compound [Au2I,III(CH3)2(μ-2-C6F4PPh2)2] was obtained from the reaction of the di(benzoato)digold(II) complex with dimethylzinc. This compound is structurally similar to its tetraprotio analogue. The cycloaurated dinuclear gold complexes [Au2(μ-C6H3-n-F-2-PPh2)2] (n = 5, 6) were made similarly to the 2-C6F4PPh2 analogue from the appropriate lithium or tin reagents, though in some cases the dimers were formed in admixture with the corresponding gold(I) tetramers. Like their tetrafluoro analogues, the 6-fluoro complexes [Au2X2(μ-C6H3-6-F-2-PPh2)2] (X = Cl, Br, I) rearrange on heating to give the heterovalent gold(I)-gold(III) species [XAu(µ-C6H3-6-F-2-PPh2)(κ2-C6H3-6-F-2-PPh2)AuX]. Thus, the presence of a fluorine atom in place of hydrogen in the 6-position of the bridging aryl group is sufficient to stop the isomerisation of the digold(II) complexes [Au2X2(μ-2-C6H4PPh2)2] at the gold(I)-gold(III) stage and to prevent subsequent C-C coupling of the aryl groups at the gold(III) centre. In contrast, the dihalodigold(II) complexes containing the 5-fluoro substituted ligand undergo reductive elimination and coupling of the metallated aryl groups to give the digold(I) biphenyldiyl complexes [Au2X2(2,2'-Ph2P-5-FC6H3C6H3-5-F-PPh2)] (X = Cl, Br, I). The described complexes were characterised using 1H NMR, 31P NMR, 19F NMR spectroscopy, elemental analysis, mass spectroscopy, IR spectroscopy, X-ray diffraction and 197Au Mössbauer spectroscopy.

<p>In a time of global environmental problems due to overuse of fossil fuels, and a subsequent depletion of the supplies, hydrogen is considered as one of the most important renewable future fuels for use in clean energy systems with zero greenhouse-gas emission. Hydrogen storage is the main issue that needs to be solved before the technology can be implemented into key areas such as transport. The high energy density, good stability and reversibility of metal hydrides make them appealing as hydrogen storage materials. In this thesis research on synthesis and hydrogen absorption properties for intermetallic compounds based on scandium and aluminium is reported. The compounds were synthesized by arc melting or induction melting and exposed to hydrogen in a high pressure furnace. Desorption investigations were performed by thermal desorption spectroscopy. The samples were analyzed by x-ray powder diffraction and electron microscopy. ScAlNi, crystallizing in the MgZn2-type structure (space group: P63/mmc; a = 5.1434(1) Å, c = 8.1820(2) Å), was found to absorb hydrogen by two different mechanisms at different temperature regions. At ~120 °C hydrogen was absorbed by solid solution formation with estimated compositions up to ScAlNiH0.5. At ~500 °C hydrogen was absorbed by disproportionation of ScAlNi into ScH2 and AlNi. The reaction was found to be fully reversible due to destabilization effects which lowered the decomposition temperature of ScH2 by ~460 °C.</p>

We present the first spectral search for neutron stars (NSs) in low-mass X-ray binaries (LMXBs) between outbursts in the Small Magellanic Cloud (SMC). We identify and discuss candidate LMXBs in quiescence in the SMC using deep Chandra X-ray observations of two portions of the SMC. We produce X-ray color-magnitude-diagrams of XRSs of these two fields and identify 10 candidates for quiescent NS LMXBs. Spectral fitting and searches for optical counterparts rule out five, leaving five candidate quiescent NS LMXBs. We estimate that we are sensitive to ~10% of quiescent NS LMXBs in our fields. Our fields include 4.410^7 M of stellar mass, giving an upper limit of 10^{6} LMXBs per M in the SMC. We place a lower limit on the average duty cycle of NS LMXBs as ~0.003.

RNA metabolism includes all the processes required for RNA synthesis, maturation, and degradation in living cells. Ribonucleases (RNases) are involved in RNA maturation and degradation, two essential processes in gene expression and regulation in both prokaryotes and eukaryotes. Oligoribonuclease (Orn) has an important role in eliminating small oligonucleotides (nano-RNA), the last step in mRNA degradation. In E. coli, Orn is the only essential exoribonuclease. The enzyme has been shown to form a stable dimer, both in solution and in the crystalline form. Analysis of the three-dimensional structure of Orn allowed us to hypothesize that dimerization is essential for enzyme catalysis. In order to test the hypothesis, I analyzed a number of deletion and point mutants of Orn and determined that tryptophan 143 is essential for dimerization. A W143A mutant is unable to dimerize and has very little activity, similar to that of an active site mutant (D162A). The atomic structure of the W143A mutant, solved at a resolution of 1.9 Å, showed that although the overall three-dimensional fold is similar to that of the wild-type protein, minor differences exist that could account for the monomeric behavior in solution. A flexible Arg174 is repositioned into the cavity created by the missing Trp143. In this new orientation Arg174 protrudes into a hydrophobic pocket in the dimerization interface and is proposed to produce sufficient unfavorable interactions to keep the monomers apart in solution. All these data suggest that dimerization of Orn is essential for its activity. The human homolog of Orn, also known as small fragment nuclease (Sfn), has been shown to degrade short single-stranded RNA, the last step in mRNA decay. In order to determine the mechanism of action of Sfn and its role in the cell, we solved the crystal structure of a truncated form of Sfn at a resolution of 2.6 Å. This mutant form of Sfn lacks the C-terminal 21 amino acids (Sfn-∆C21) yet is as efficient as full length Sfn on model substrates. Interestingly, Sfn is not as active as E. coli Orn in in vitro assays. Analysis of the atomic structure revealed that the active site cleft in Sfn is narrower than the corresponding active site in E. coli. We propose a model for how this narrower cleft may explain the lower in vitro activity. Bacillus subtilis does not have an Orn homolog and until recently, the enzyme responsible for nano-RNA degradation in this organism was unknown. YtqI (also termed nrnA or nanoRNase), a protein unrelated to E. coli Orn, was recently shown to be responsible for the digestion of oligonucleotides in B. subtilis. In order to better understand the mechanism of action of YtqI, I solved its crystal structure at a resolution of 2.0 Å. The nuclease has a RecJ-like fold with two globular domains connected via a flexible linker that forms a central groove. On one side of the groove, the larger N-terminal domain harbors the putative active site, while on the opposite side, the C-terminal domain includes a putative RNA binding domain. The structure of YtqI provides insights into how this enzyme binds and digests oligoribonucleotides. The studies described here provide a better understanding of the mechanism of action for several exoribonucleases that act on nano-RNA oligonucleotides - Oligoribonuclease from E. coli, its close homolog in humans (Small fragment nuclease), as well as a functional homolog in Bacillus (YtqI). This work is relevant to understanding RNA metabolism, which is an essential process for survival of both eukaryotic and prokaryotic organisms.

Density functional theory is used to calculate the core excitation spectra of titanium structures. Specifically, the core-hole approximation is used. In this scenario, the excitation energies of core electrons are calculated using the approximation that the core energy level be frozen throughout the relaxation process of the orbitals. This allows a more acurate determination of the resulting X-ray spectra. The method described has been implemented in an NWChem module.