Detecting actions of fruit flies

In this thesis we describe a system that tracks fruit flies in video and automatically detects and classifies their actions. We introduce Caltech Fly-vs-Fly Interactions, a new dataset that contains hours of video showing pairs of fruit flies engaging in social interactions, and is published with complete expert annotations and articulated pose trajectory features. We compare experimentally the value of a frame-level feature representation with the more elaborate notion of bout features that capture the structure within actions. Similarly, we compare a simple sliding window classifier architecture with a more sophisticated structured output architecture, and find that window based detectors outperform the much slower structured counterparts, and approach human performance. In addition we test the top performing detector on the CRIM13 mouse dataset, finding that it matches the performance of the best published method.

Equilibration of a liquid droplet-vapor-gas mixture downstream of a shock wave

The equations of motion for the flow of a mixture of liquid droplets, their vapor, and an inert gas through a normal shock wave are derived. A set of equations is obtained which is solved numerically for the equilibrium conditions far downstream of the shock. The equations describing the process of reaching equilibrium are also obtained. This is a set of first-order nonlinear differential equations and must also be solved numerically. The detailed equilibration process is obtained for several cases and the results are discussed.

I. The attenuation and dispersion of sound in a condensing medium. II. The flow of a gas-particle mixture downstream of a normal shock in a nozzle

I. The attenuation of sound due to particles suspended in a gas was first calculated by Sewell and later by Epstein in their classical works on the propagation of sound in a two-phase medium. In their work, and in more recent works which include calculations of sound dispersion, the calculations were made for systems in which there was no mass transfer between the two phases. In the present work, mass transfer between phases is included in the calculations.

The attenuation and dispersion of sound in a two-phase condensing medium are calculated as functions of frequency. The medium in which the sound propagates consists of a gaseous phase, a mixture of inert gas and condensable vapor, which contains condensable liquid droplets. The droplets, which interact with the gaseous phase through the interchange of momentum, energy, and mass (through evaporation and condensation), are treated from the continuum viewpoint. Limiting cases, for flow either frozen or in equilibrium with respect to the various exchange processes, help demonstrate the effects of mass transfer between phases. Included in the calculation is the effect of thermal relaxation within droplets. Pressure relaxation between the two phases is examined, but is not included as a contributing factor because it is of interest only at much higher frequencies than the other relaxation processes. The results for a system typical of sodium droplets in sodium vapor are compared to calculations in which there is no mass exchange between phases. It is found that the maximum attenuation is about 25 per cent greater and occurs at about one-half the frequency for the case which includes mass transfer, and that the dispersion at low frequencies is about 35 per cent greater. Results for different values of latent heat are compared.

II. In the flow of a gas-particle mixture through a nozzle, a normal shock may exist in the diverging section of the nozzle. In Marble’s calculation for a shock in a constant area duct, the shock was described as a usual gas-dynamic shock followed by a relaxation zone in which the gas and particles return to equilibrium. The thickness of this zone, which is the total shock thickness in the gas-particle mixture, is of the order of the relaxation distance for a particle in the gas. In a nozzle, the area may change significantly over this relaxation zone so that the solution for a constant area duct is no longer adequate to describe the flow. In the present work, an asymptotic solution, which accounts for the area change, is obtained for the flow of a gas-particle mixture downstream of the shock in a nozzle, under the assumption of small slip between the particles and gas. This amounts to the assumption that the shock thickness is small compared with the length of the nozzle. The shock solution, valid in the region near the shock, is matched to the well known small-slip solution, which is valid in the flow downstream of the shock, to obtain a composite solution valid for the entire flow region. The solution is applied to a conical nozzle. A discussion of methods of finding the location of a shock in a nozzle is included.

The organometallic chemistry of the Ru(001) surface

The organometallic chemistry of the hexagonally close-packed Ru(001) surface has been studied using electron energy loss spectroscopy and thermal desorption mass spectrometry. The molecules that have been studied are acetylene, formamide and ammonia. The chemistry of acetylene and formamide has also been investigated in the presence of coadsorbed hydrogen and oxygen adatoms.

Acetylene is adsorbed molecularly on Ru(001) below approximately 230 K, with rehybridization of the molecule to nearly sp^3 occurring. The principal decomposition products at higher temperatures are ethylidyne (CCH_3) and acetylide (CCH) between 230 and 350 K, and methylidyne (CH) and surface carbon at higher temperatures. Some methylidyne is stable to approximately 700 K. The preadsorption of hydrogen does not alter the decomposition products of acetylene, but reduces the saturation coverage and also leads to the formation of a small amount of ethylene (via an η^2-CHCH_2 species) which desorbs molecularly near 175 K. Preadsorbed oxygen also reduces the saturation coverage of acetylene but has virtually no effect on the nature of the molecularly chemisorbed acetylene. It does, however, lead to the formation of an sp^2-hybridized vinylidene (CCH_2) species in the decomposition of acetylene, in addition to the decomposition products that are formed on the clean surface. There is no molecular desorption of chemisorbed acetylene from clean Ru(001), hydrogen-presaturated Ru(001), or oxygen-presaturated Ru(001).

The adsorption and decomposition of formamide has been studied on clean Ru(001), hydrogen-presaturated Ru(001), and Ru(001)-p(1x2)-O (oxygen adatom coverage = 0.5). On clean Ru(001), the adsorption of low coverages of formamide at 80 K results in CH bond cleavage and rehybridization of the carbonyl double bond to produce an η^2 (C,O)-NH_2CO species. This species is stable to approximately 250 K at which point it decomposes to yield a mixture of coadsorbed carbon monoxide, ammonia, an NH species and hydrogen adatoms. The decomposition of NH to hydrogen and nitrogen adatoms occurs between 350 and 400 K, and the thermal desorption products are NH_3 (-315 K), H_2 (-420 K), CO (-480 K) and N_2 (-770 K). At higher formamide coverages, some formamide is adsorbed molecularly at 80 K, leading both to molecular desorption and to the formation of a new surface intermediate between 300 and 375 K that is identified tentatively as η^1(N)-NCHO. On Ru(001)- p(1x2)-O and hydrogen-presaturated Ru(001), formamide adsorbs molecularly at 80 K in an η^1(O)- NH_2CHO configuration. On the oxygen-precovered surface, the molecularly adsorbed formamide undergoes competing desorption and decomposition, resulting in the formation of an η^2(N,O)-NHCHO species (analogous to a bidentate formate) at approximately 265 K. This species decomposes near 420 K with the evolution of CO and H_2 into the gas phase. On the hydrogen precovered surface, the Η^1(O)-NH_2CHO converts below 200 K to η^2(C,O)-NH_2CHO and η^2(C,O)-NH^2CO, with some molecular desorption occurring also at high coverage. The η^2(C,O)-bonded species decompose in a manner similar to the decomposition of η^2(C,O)-NH_2CO on the clean surface, although the formation of ammonia is not detected.

Ammonia adsorbs reversibly on Ru(001) at 80 K, with negligible dissociation occurring as the surface is annealed The EEL spectra of ammonia on Ru(001) are very similar to those of ammonia on other metal surfaces. Off-specular EEL spectra of chemisorbed ammonia allow the v(Ru-NH_3) and ρ(NH_3) vibrational loss features to be resolved near 340 and 625 cm^(-1), respectively. The intense δ_g (NH_3) loss feature shifts downward in frequency with increasing ammonia coverage, from approximately 1160 cm^(-1) in the low coverage limit to 1070 cm^(-1) at saturation. In coordination compounds of ammonia, the frequency of this mode shifts downward with decreasing charge on the metal atom, and its downshift on Ru(001) can be correlated with the large work function decrease that the surface has previously been shown to undergo when ammonia is adsorbed. The EELS data are consistent with ammonia adsorption in on-top sites. Second-layer and multilayer ammonia on Ru(001) have also been characterized vibrationally, and the results are similar to those obtained for other metal surfaces.

2,4-dimethylene-1,3-cyclobutanediyl and 2,4-dimethylenebicyclobutane. Synthesis, spectroscopy, and reactivity of a triplet biradical and its covalent isomer

The preparation and direct observation of triplet 2,4-dimethylene-1,3- cyclobutanediyl (1), the non-Kekule isomer of benzene, is described. The biradical was generated by photolysis of 5,6-dimethylene-2,3- diazabicyclo[2.1.1]hex-2-ene (2) (which was synthesized in several steps from benzvalene) under cryogenic, matrix-isolation conditions. Biradical 1 was characterized by EPR spectroscopy (‌‌‌‌‌│D/hc│ =0.0204 cm^(-1), │E/hc│ =0.0028 cm^(-1)) and found to have a triplet ground state. The Δm_s= 2 transition displays hyperfine splitting attributed to a 7.3-G coupling to the ring methine and a 5.9-G coupling to the exocyclic methylene protons. Several experiments, including application of the magnetophotoselection (mps) technique in the generation of biradical 1, have allowed a determination of the zero-field triplet sublevels as x = -0.0040, y = +0.0136, and z = -0.0096 cm^(-1), where x and y are respectively the long and short in-plane axes and z the out-of-plane axis of 1.

Triplet 1 is yellow-orange and displays highly structured absorption (λ_(max)= 506 nm) and fluorescence (λ_(max) = 510 nm) spectra, with vibronic spacings of 1520 and 620 cm^(-1) for absorption and 1570 and 620 cm^(-1) for emission. The spectra were unequivocally assigned to triplet 1 by the use of a novel technique that takes advantage of the biradical's photolability. The absorption є = 7200 M^(-1) cm^(-1) and f = 0.022, establishing that the transition is spin-allowed. Further use of the mps technique has demonstrated that the transition is x-polarized, and the excited state 1s therefore of B_(1g) symmetry, in accord with theoretical predictions.

Thermolysis or direct photolysis of diazene 2 in fluid solution produces 2,4- dimethylenebicyclo[l.l.0]butane (3), whose ^(l)H NMR spectrum (-80°C, CD_(2)Cl_(2)) consists of singlets at δ 4.22 and 3.18 in a 2:1 ratio. Compound 3 is thermally unstable and dimerizes with second-order kinetics between -80 and -25°C (∆H^(‡) = 6.8 kcal mol^(-1), (∆s^(‡) = -28 eu) by a mechanism involving direct combination of two molecules of 3 in the rate-determining step. This singlet-manifold reaction ultimately produces a mixture of two dimers, 3,8,9- trimethylenetricyclo[5.1.1.0^(2,5)]non-4-ene (75) and trans-3,10-dimethylenetricyclo[6.2.0.0^(2,5)]deca-4,8-diene (76t), with the former predominating. In contrast, triplet-sensitized photolysis of 2, which leads to triplet 1, provides, in addition to 75 and 76t, a substantial amount of trans-5,10- dimethylenetricyclo[6.2.0.0^(3,6)]deca-3,8-diene (77t) and small amounts of two unidentified dimers.

In addition, triplet biradical 1 ring-closes to 3 in rigid media both thermally (77-140 K) and photochemically. In solution 3 forms triplet 1 upon energy transfer from sensitizers having relatively low triplet energies. The implications of the thermal chemistry for the energy surfaces of the system are discussed.

Synthetic, structural and mechanistic studies of interactions of carbon, nitrogen, and oxygen nucleophiles with bis-pentamethylcyclopentadienyl zirconium and hafnium derivatives

The reactivity of permethylzirconocene and permethylhafnocene complexes with various nucleophiles has been investigated. Permethylzirconocene reacts with sterically hindered ketenes and allenes to afford metallacycle products. Reaction of these cummulenes with permethylzirconocene hydride complexes affords enolate and σ-allyl species, respectively. Reactions which afford enolate products are nonstereospecific, whereas reactions which afford allyl products initially give a cis-σ-allyl complex which rearranges to its trans isomer. The mechanism of these reactions is proposed to occur either by a Lewis Acid-Lewis Base interaction (ketenes) or by formation of a π-olefin intermediate (allenes).

Permethylzirconocene haloacyl complexes react with strong bases such as lithium diisopropylamide or methylene trimethylphosphorane to afford ketene compounds. Depending on the size of the alkyl ketene substituent, the hydrogenation of these compounds affords enolate-hydride products with varying degrees of stereoselectivity. The larger the substituent, the greater is the selectivity for cis hydrogenation products.

The reaction of permethylzirconocene dihydride and permethylhafnocene dihydride with methylene trimethylphosphorane affords methyl-hydride and dimethyl derivatives. Under appropriate conditions, the metallated-ylide complex 1, (η^5-C_5(CH_3)_5)_2 Zr(H)CH_2PMe_2CH_2, is also obtained and has been structurally characterized by X-ray diffraction techniques. Reaction of 1 with CO affords (η^5-C_5(CH_3)_5)_2 Zr(C,O-η^2 -(PMe_3)HC=CO)H which exists in solution as an equilibrium mixture of isomers. In one isomer (2), the η^2-acyl oxygen atom occupies a lateral equatorial coordination position about zirconium, whereas in the other isomer (3), the η-acyl oxygen atom occupies the central equatorial position. The equilibrium kinetics of the 2→3 isomerization have been studied and the structures of both complexes confirmed by X-ray diffraction methods. These studies suggest a mechanism for CO insertion into metal-carbon bonds of the early transition metals.

Permethylhafnocene dihydride and permethylzirconocene hydride complexes react with diazoalkanes to afford η^2-N, N' -hydrazonido species in which the terminal nitrogen atom of the diazoalkane molecule has inserted into a metal-hydride or metal-carbon bond. The structure of one of these compounds, Cp*_2Zr(NMeNCTol_2)OH, has been determined by X-ray diffraction techniques. Under appropriate conditions, the hydrazonido-hydride complexes react with a second equivalent of diazoalkene to afford η' -N-hydrazonido-η^2-N, N' -hydrazonido species.

Liquid silicate equation of state : using shock waves to understand the properties of the deep Earth

The equations of state (EOS) of several geologically important silicate liquids have been constrained via preheated shock wave techniques. Results on molten Fe₂SiO₄ (fayalite), Mg₂SiO₄ (forsterite), CaFeSi₂O₆ (hedenbergite), an equimolar mixture of CaAl₂Si₂O₈-CaFeSi₂O₆ (anorthite-hedenbergite), and an equimolar mixture of CaAl₂Si₂O₈-CaFeSi₂O₆-CaMgSi₂O₆(anorthite-hedenbergite-diopside) are presented. This work represents the first ever direct EOS measurements of an iron-bearing liquid or of a forsterite liquid at pressures relevant to the deep Earth (> 135 GPa). Additionally, revised EOS for molten CaMgSi₂O₆ (diopside), CaAl₂Si₂O₈ (anorthite), and MgSiO₃ (enstatite), which were previously determined by shock wave methods, are also presented.

The liquid EOS are incorporated into a model, which employs linear mixing of volumes to determine the density of compositionally intermediate liquids in the CaO-MgO-Al₂O₃-SiO₂-FeO major element space. Liquid volumes are calculated for temperature and pressure conditions that are currently present at the core-mantle boundary or that may have occurred during differentiation of a fully molten mantle magma ocean.

The most significant implications of our results include: (1) a magma ocean of either chondrite or peridotite composition is less dense than its first crystallizing solid, which is not conducive to the formation of a basal mantle magma ocean, (2) the ambient mantle cannot produce a partial melt and an equilibrium residue sufficiently dense to form an ultralow velocity zone mush, and (3) due to the compositional dependence of Fe2+ coordination, there is a threshold of Fe concentration (molar X_Fe ≤ 0.06) permitted in a liquid for which its density can still be approximated by linear mixing of end-member volumes.

The electrocatalytic and stoichiometric oxidation chemistry of binuclear ruthenium complexes incorporating the anionic tripod ligand {(η5-C5H5)Co[P(OCH3)2(=O)]3}-

The anionic tripod ligand NaLoMe (L_(oMe) - = [(η^5-C_5H_5)Co{P(O)(OCH_3)_2}_3]^-) reacts with RuO_4 in a biphasic reaction mixture of 1% H_2SO_4 and CCI_4 to afford [(L_(oMe) (HO)Ru^(IV) (µ-O)_2Ru ^(IV)(OH)(L_(oMe)] (1), which is treated with aqueous CF_3S0_3H to generate [(L_(oMe)(H_2O)Ru^(IV) (µ-O)_2R^(IV) (OH_2)(L_(oMe)][CF_3SO_3]_2 ([H_21][CF_3SO_3]_2). Addition of iodosobenzene to an acetonitrile solution of this salt yields [(L_(oMe)(O)Ru^v(µ-0)2Ru^v-(O)(_(LoMe)] (2). The dimer 1 can be reduced chemically or electrochemically to the Ru^(III)- Ru^(III) dimers [(L_(oMe)(H_20)Ru^(III) (µ-OH)_2Ru^(III) (OH_2)(L_(oMe)) ]^2+ and [(L_(oMe)) ^(III) (µ-0Hh(µ-0H2)Ru^(III) (L_(oMe)]^2+ which interconvert in aqueous media. Two electron processes dominate both the bulk chemistry and the electrochemistry of 1. Among these processes are the quasi-reversible Ru^(IV) - Ru^(IV)/Ru^(III)- Ru^(III) and Ru^(III)- Ru^(III)/ Ru^(II)- Ru^(II) reductions and a largely irreversible Ru^(V) - Ru^(V)/ Ru^(IV) - Ru^(IV)/oxidation. The dioxo dimer 2 oxidizes alcohols and aldehydes in organic media to afford 1 and the corresponding aldehydes and acids. Analogously, the Ru^(V) - Ru^(V)/ Ru^(IV)- Ru^(IV) redox wave mediates the electrooxidation of alcohols and aldehydes in aqueous buffer. In this system, substrates can be oxidized completely to CO_2. The kinetic behavior of these oxidations was examined by UV-vis and chronoamperometry, respectively, and the chemistry is typical of metal-oxo complexes, indicating that electronic coupling between two metal centers does not dramatically affect the metal-oxo chemistry. Dimer [H_21]^(2+) also reacts with alcohols, aldehydes, and triphenylphosphine in CH_3CN to afford Ru^(III)- Ru^(III) products including [(L_(oMe))CH_3CN) Ru^(III) (µ-OH)_2 Ru^(III) (NCCH_3)( L_(oMe))][CF_3SO_3]2 (characterized by X-ray crystallography) and the corresponding organic products. Reaction of 1 with formaldehyde in aqueous buffer quantitatively affords the triply bridged dimer [(L_(oMe)Ru^(III) (µ-OH)2- (µ-HCOO) Ru^(III) (L_(oMe)][CF_3SO_3] (characterized by X-ray crystallography). This reaction evidently proceeds by two parallel inner-sphere pathways, one of which is autocatalytic. Neither pathway exhibits a primary isotope effect suggesting the rate determining process could be the formation of an intermediate, perhaps a Ru^(IV) - Ru^(IV) formate adduct. The Ru^(III)- Ru^(III)formate adduct is easily oxidized to the Ru^(IV) - Ru^(IV) analog [(L_(oMe)Ru^(IV)(µ-OH)_2-(µ-HCOO) Ru^(IV) (L_(oMe)][CF_3SO_3], which, after isolation, reacts slowly with aqueous formaldehyde to generate free formate and the Ru^(III)- Ru^(III) formate adduct. These dimers function as catalysts for the electrooxidation of formaldehyde at low anodic potentials (+0.0 V versus SCE in aqueous buffer, pH 8.5) and enhance the activity of Nafion treated palladium/carbon heterogeneous fuel cell catalysts.

The design and synthesis of a true, heterogeneous, asymmetric catalyst

This work describes the design and synthesis of a true, heterogeneous, asymmetric catalyst. The catalyst consists of a thin film that resides on a high-surface- area hydrophilic solid and is composed of a chiral, hydrophilic organometallic complex dissolved in ethylene glycol. Reactions of prochiral organic reactants take place predominantly at the ethylene glycol-bulk organic interface.

The synthesis of this new heterogeneous catalyst is accomplished in a series of designed steps. A novel, water-soluble, tetrasulfonated 2,2'-bis (diphenylphosphino)-1,1'-binaphthyl (BINAP-4S0_3Na) is synthesized by direct sulfonation of 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP). The rhodium (I) complex of BINAP-4SO_3Na is prepared and is shown to be the first homogeneous catalyst to perform asymmetric reductions of prochiral 2-acetamidoacrylic acids in neat water with enantioselectivities as high as those obtained in non-aqueous solvents. The ruthenium (II) complex, [Ru(BINAP-4SO_3Na)(benzene)Cl]Cl is also synthesized and exhibits a broader substrate specificity as well as higher enantioselectivities for the homogeneous asymmetric reduction of prochiral 2-acylamino acid precursors in water. Aquation of the ruthenium-chloro bond in water is found to be detrimental to the enantioselectivity with some substrates. Replacement of water by ethylene glycol results in the same high e.e's as those found in neat methanol. The ruthenium complex is impregnated onto a controlled pore-size glass CPG-240 by the incipient wetness technique. Anhydrous ethylene glycol is used as the immobilizing agent in this heterogeneous catalyst, and a non-polar 1:1 mixture of chloroform and cyclohexane is employed as the organic phase.

Asymmetric reduction of 2-(6'-methoxy-2'-naphthyl)acrylic acid to the non-steroidal anti-inflammatory agent, naproxen, is accomplished with this heterogeneous catalyst at a third of the rate observed in homogeneous solution with an e.e. of 96% at a reaction temperature of 3°C and 1,400 psig of hydrogen. No leaching of the ruthenium complex into the bulk organic phase is found at a detection limit of 32 ppb. Recycling of the catalyst is possible without any loss in enantioselectivity. Long-term stability of this new heterogeneous catalyst is proven by a self-assembly test. That is, under the reaction conditions, the individual components of the present catalytic system self-assemble into the supported-catalyst configuration.

The strategies outlined here for the design and synthesis of this new heterogeneous catalyst are general, and can hopefully be applied to the development of other heterogeneous, asymmetric catalysts.

Reactivity of titanocene methylidene with metal halides, alkene sulfides, and alkene oxides

Titanocene metallacyclobutanes show a wide variety of reactivites with organic and inorganic reagents. Their reactions include methylene transfer to organic carbonyls, formation of enolates, electron transfer from activated alkyl chlorides, olefin metathesis, ring opening polymerization. Recently, preparations of heterobinuclear µ-methylene complexes were reported. In this thesis, mechanistic, synthetic, and structural studies of the heterobinuclear µ-methylene complexes will be described. Also, the reaction of titanocene methylidene trimethylphosphine complex with alkene sulfide and styrene sulfide will be presented.

Heterobinuclear µ-methylene-µ-methyl complexes C_(p2)Ti(µ-CH_2)( µ-CH_3)M(1,5-COD) have been prepared (M = Rh, Ir). X-ray crystallography showed that the methyl group of the complex was bonded to the rhodium and bridges to the titanium through an agostic bond. The ^(1)H,^(13)CNMR, IR spectra along with partial deuteration studies supported the structure in both solution and solid state. Activation of the agostic bond is demonstrated by the equilibration of the µ-CH_3 and µ-CH_2 groups. A nonlinear Arrhenius plot, an unusually large kinetic isotope effect (24(5)), and a large negative activation entropy (-64(3)eu) can be explained by the quantum-mechanical tunneling. Calculated rate constants with Bell-type barrier fitted well with the observed one. This equilibration was best explained by a 4e-4c mechanism (or σ bond metathesis) with the character of quantum-mechanical tunneling.

Heterobinuclear µ-methylene-µ-phenyl complexes were synthesized. Structural study of C_(p2)Ti(µ-CH_(2))(µ-p-Me_(2)NC_(6)H_(4))Rh(l,5-COD) showed that the two metal atoms are bridged by the methylene carbon and the ipso carbon of the p-N,N-dimethylarninophenyl group. The analogous structure of C_(p2))Ti(µ-CH_(2))(µ-o-MeOC_(6)H_(4))Rh(1,5-COD) has been verified by the differential NOE. The aromaticity of the phenyl group observed by ^(1)H NMR, was confirmed by the comparison of the C-C bond lengths in the crystallographic structure. The unusual downfield shifts of the ipso carbon in the ^(13)C NMR are assumed to be an indication of the interaction between the ipso carbon and electron-deficient titanium.

Titanium-platinum heterobinuclear µ-methylene complexes C_(p2)Ti(µ-CH_(2))(µ -X)Pt(Me)(PM_(2)Ph) have been prepared (X= Cl, Me). Structural studies indicate the following:(1) the Ti-CH2 bond possesses residual double bond character, (2) there is a dative Pt→Ti interaction which may be regarded as a π back donation from the platinum atom to the 'Ti=CH_(2)'' group, and (3) the µ-CH_3 group is bound to the titanium atom through a three-center, two-electron agostic bond.

Titanocene (η^(2)-thioformaldehyde)•PMe_3 was prepared from C_(p2)Ti=CH_(2)•PMe_3 and sulfur-containing organic compounds (e.g. alkene sulfide, triphenylphosphine sulfide) including elemental sulfur. Mechanistic studies utilizing trans-styrene sulfide-d_1 suggested the stepwise reaction to explain equimolar mixture of trans- and cis-styrene-d_1 as by-products. The product reacted with methyl iodide to produce cationic titanocene (η_(2)-thiomethoxymethyl) complex. Complexes having less coordinating anion like BF_4 or BPh_4 could be obtained through metathesis. Together with structural analyses, the further reactivities of the complexes have been explored.

The complex C_(p2)TiOCH_(2)CH(Ph)CH_2 was prepared from the compound C_(p2)Ti=CH_(2)-PMe_3 and styrene oxide. The product was characterized with ^(1)H-^(1)H correlated 2-dimensional NMR, selective decoupling of ^(1)H NMR, and differential NOE. Stereospecificity of deuterium in the product was lost when trans-styrene oxide-d_1 was allowed to react. Relative rates of the reaction were measured with varying substituents on the phenyl ring. Better linearity (r = -0.98, p^(+) = -0.79) was observed with σ_(p)^(+)than σ(r = -0.87, p = -1.26). The small magnitude of p^+ value and stereospecificity loss during the formation of product were best explained by the generation of biradicals, but partial generation of charge cannot be excluded. Carbonylation of the product followed by exposure to iodine yields the corresponding β-phenyl γ-lactone.

Probing the thermodynamic properties of mantle rocks in solid and liquid states

Our understanding of the structure and evolution of the deep Earth is strongly linked to knowledge of the thermodynamic properties of rocky materials at extreme temperatures and pressures. In this thesis, I present work that helps constrain the equation of state properties of iron-bearing Mg-silicate perovskite as well as oxide-silicate melts. I use a mixture of experimental, statistical, and theoretical techniques to obtain knowledge about these phases. These include laser-heated diamond anvil cell experiments, Bayesian statistical analysis of powder diffraction data, and the development of a new simplified model for understanding oxide and silicate melts at mantle conditions. By shedding light on the thermodynamic properties of such ubiquitous Earth-forming materials, I hope to aid our community’s progress toward understanding the large-scale processes operating in the Earth’s mantle, both in the modern day and early in Earth’s history.

Oxidative chemisorption of SO_2 on γ - Al_2O_3 and deposition of H_2-permselective SiO_2 films

The interaction of SO_2 with γ - Al_2O_3 and the deposition of H_2 permselective SiO_2 films have been investigated. The adsorption and oxidative adsorption of SO_2 on γ - Al_2O_3 have been examined at temperatures 500-700°C by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). At temperatures above 500°C most of SO_2 adsorbed on the strong sites on alumina. The adsorbed SO_2 species was characterized by an IR band at 1065 cm^(-1). The equilibrium coverage and initial rate of adsorption decreased with temperature suggesting a two-step adsorption. When γ - Al_2O_3 was contacted with a mixture of SO_2 and O_2, adsorption of SO_2 and oxidation of the adsorbed SO_2 to a surface sulfate characterized by broad IR bands at 1070 cm^(-1), 1390 cm^(-1) took place. The results of a series of TGA experiments under different atmospheres strongly suggest that surface SO_2 and surface sulfate involve the same active sites such that SO_2 adsorption is inhibited by already formed sulfate. The results also indicate a broad range of site strengths.

The desorption of adsorbed SO_2 and the reductive desorption of oxidatively adsorbed SO_2 have been investigated by microreactor experiments and thermogravimetric analysis (TGA). Temperature programmed reduction (TPR) of adsorbed SO_2 showed that SO_2 was desorbed without significant reaction with H_2 when H_2 concentration was low while considerable reaction occurred when 100% H_2 was used. SO_2 adsorbed on the strong sites on alumina was reduced to sulfur and H_2S. The isothermal reduction experiments of oxidatively adsorbed SO_2 reveal that the rate of reduction is very slow below 550°C even with 100% H_2. The reduction product is mainly composed of SO_2. TPR experiments of oxidatively adsorbed SO_2 showed that H_2S arose from a sulfate strongly chemisorbed on the surface.

Films of amorphous SiO_2 were deposited within the walls of porous Vycor tubes by SiH_4 oxidation in an opposing reactants geometry : SiH_4 was passed inside the tube while O_2 was passed outside the tube. The two reactants diffused opposite to each other and reacted within a narrow front inside the tube wall to form a thin SiO_2 film. Once the pores were plugged the reactants could not reach each other and the reaction stopped. At 450°C and 0.1 and 0.33 atm of SiH_4 and O_2, the reaction was complete within 15 minutes. The thickness of the SiO_2 film was estimated to be about 0.1 µm. Measurements of H_2 and N_2 permeation rates showed that the SiO_2 film was highly selective to H_2 permeation. The H_2:N_2 flux at 450°C varied between 2000-3000.

Thin SiO_2 films were heat treated in different gas mixtures to determine their stability in functioning as high-temperature hydrogen-permselective membranes. The films were heat-treated at 450-700°C in dry N_2, dry O_2, N_2-H_2O, and O_2-H_2O mixtures. The permeation rates of H_2 and N_2 changed depending on the original conditions of film formation as well as on the heat treatment. Heating in dry N_2 slowly reduced the permeation rates of both H_2 and N_2. Heating in a N_2-H_2O atmosphere led to a steeper decline of H_2 permeability. But the permeation rate of N_2 increased or decreased according to whether the film deposition had been carried out in the absence or presence of H_2O vapor, respectively. Thermal treatment in O_2 caused rapid decline of the permeation rates of H_2 and N_2 in films that were deposited under dry conditions. The decline was moderate in films deposited under wet conditions.

Neuronal mechanism of state control in Drosophila melanogaster

The changes in internal states, such as fear, hunger and sleep affect behavioral responses in animals. In most of the cases, these state-dependent influences are “pleiotropic”: one state affects multiple sensory modalities and behaviors; “scalable”: the strengths and choices of such modulations differ depending on the imminence of demands; and “persistent”: once the state is switched on the effects last even after the internal demands are off. These prominent features of state-control enable animals to adjust their behavioral responses depending on their internal demands. Here, we studied the neuronal mechanisms of state-controls by investigating energy-deprived state (hunger state) and social-deprived state of fruit flies, Drosophila melanogaster, as prototypic models. To approach these questions, we developed two novel methods: a genetically based method to map sites of neuromodulation in the brain and optogenetic tools in Drosophila.

These methods, and genetic perturbations, reveal that the effect of hunger to alter behavioral sensitivity to gustatory cues is mediate by two distinct neuromodulatory pathways. The neuropeptide F (NPF) – dopamine (DA) pathway increases sugar sensitivity under mild starvation, while the adipokinetic hormone (AKH)- short neuropeptide F (sNPF) pathway decreases bitter sensitivity under severe starvation. These two pathways are recruited under different levels of energy demands without any cross interaction. Effects of both of the pathways are mediated by modulation of the gustatory sensory neurons, which reinforce the concept that sensory neurons constitute an important locus for state-dependent control of behaviors. Our data suggests that multiple independent neuromodulatory pathways are underlying pleiotropic and scalable effects of the hunger state.

In addition, using optogenetic tool, we show that the neural control of male courtship song can be separated into probabilistic/biasing, and deterministic/command-like components. The former, but not the latter, neurons are subject to functional modulation by social experience, supporting the idea that they constitute a locus of state-dependent influence. Interestingly, moreover, brief activation of the former, but not the latter, neurons trigger persistent behavioral response for more than 10 min. Altogether, these findings and new tools described in this dissertation offer new entry points for future researchers to understand the neuronal mechanism of state control.

Variable-angle electron spectroscopic studies of various polyatomic molecular systems

The complementary techniques of low-energy, variable-angle electron-impact spectroscopy and ultraviolet variable-angle photoelectron spectroscopy have been used to study the electronic spectroscopy and structure of several series of molecules. Electron-impact studies were performed at incident beam energies between 25 eV and 100 eV and at scattering angles ranging from 0° to 90°. The energy-loss regions from 0 eV to greater than 15 eV were studied. Photoelectron spectroscopic studies were conducted using a HeI radiation source and spectra were measured at scattering angles from 45° to 90°. The molecules studied were chosen because of their spectroscopic, chemical, and structural interest. The operation of a new electron-impact spectrometer with multiple-mode target source capability is described. This spectrometer has been used to investigate the spin-forbidden transitions in a number of molecular systems.

The electron-impact spectroscopy of the six chloro-substituted ethylenes has been studied over the energy-loss region from 0-15 eV. Spin-forbidden excitations corresponding to the π → π*, N → T transition have been observed at excitation energies ranging from 4.13 eV in vinyl chloride to 3.54 eV in tetrachloroethylene. Symmetry-forbidden transitions of the type π → np have been oberved in trans-dichloroethyene and tetrachlor oethylene. In addition, transitions to many states lying above the first ionization potential were observed for the first time. Many of these bands have been assigned to Rydberg series converging to higher ionization potentials. The trends observed in the measured transition energies for the π → π*, N → T, and N → V as well as the π → 3s excitation are discussed and compared to those observed in the methyl- and fluoro- substituted ethylenes.

The electron energy-loss spectra of the group VIb transition metal hexacarbonyls have been studied in the 0 eV to 15 eV region. The differential cross sections were obtained for several features in the 3-7 eV energy-loss region. The symmetry-forbidden nature of the ¹A_1g → ¹A_1g, 2t_2g(π) → 3t_2g(π*) transition in these compounds was confirmed by the high-energy, low-angle behavior of their relative intensities. Several low lying transitions have been assigned to ligand field transitions on the basis of the energy and angular behavior of the differential cross sections for these transitions. No transitions which could clearly be assigned to singlet → triplet excitations involving metal orbitals were located. A number of states lying above the first ionization potential have been observed for the first time. A number of features in the 6-14 eV energy-loss region of the spectra of these compounds correspond quite well to those observed in free CO.

A number of exploratory studies have been performed. The π → π*, N → T, singlet → triplet excitation has been located in vinyl bromide at 4.05 eV. We have also observed this transition at approximately 3.8 eV in a cis-/trans- mixture of the 1,2-dibromoethylenes. The low-angle spectrum of iron pentacarbonyl was measured over the energy-loss region extending from 2-12 eV. A number of transitions of 8 eV or greater excitation energy were observed for the first time. Cyclopropane was also studied at both high and low angles but no clear evidence for any spin- forbidden transitions was found. The electron-impact spectrum of the methyl radical resulting from the pyrolysis of tetramethyl tin was obtained at 100 eV incident energy and at 0° scattering angle. Transitions observed at 5.70 eV and 8.30 eV agree well with the previous optical results. In addition, a number of bands were observed in the 8-14 eV region which are most likely due to Rydberg transitions converging to the higher ionization potentials of this molecule. This is the first reported electron-impact spectrum of a polyatomic free radical.

Variable-angle photoelectron spectroscopic studies were performed on a series of three-membered-ring heterocyclic compounds. These compounds are of great interest due to their highly unusual structure. Photoelectron angular distributions using HeI radiation have been measured for the first time for ethylene oxide and ethyleneimine. The measured anisotropy parameters, β, along with those measured for cyclopropane were used to confirm the orbital correlations and photoelectron band assignments. No high values of β similar to those expected for alkene π orbitals were observed for the Walsh or Forster-Coulson-Moffit type orbitals.

Reactions of platinum(II) complexes with dioxygen: progress toward alkane functionalization

Whereas stoichiometric activation of C-H bonds by complexes of transition metals is becoming increasingly common, selective functionalization of alkanes remains a formidable challenge in organometallic chemistry. The recent advances in catalytic alkane functionalization by transition-metal complexes are summarized in Chapter I.

The studies of the displacement of pentafluoropyridine in [(tmeda)Pt(CH_3)(NC_5F_5)][BAr^f_4] (1) with γ- tetrafluoropicoline, a very poor nucleophile, are reported in Chapter II. The ligand substitution occurs by a dissociative interchange mechanism. This result implies that dissociative loss of pentafluoropyridine is the rate-limiting step in the C-H activation reactions of 1.

Oxidation of dimethylplatinum(II) complexes (N-N)Pt(CH_3)_2 (N-N = tmeda(1), α-diimines) by dioxygen is described in Chapter III. Mechanistic studies suggest a two-step mechanism. First, a hydroperoxoplatinum(IV) complex is formed in a reaction between (N-N)Pt(CH_3)_2 and dioxygen. Next, the hydroperoxy complex reacts with a second equivalent of (N-N)Pt(CH_3)_2 to afford the final product, (N-N)Pt(OH)(OCH_3)(CH_3)_2. The hydroperoxy intermediate, (tmeda)Pt(OOH)(OCH_3)(CH_3)_2 (2), was isolated and characterized. The reactivity of 2 with several dime thylplatinum(II) complexes is reported.

The studies described in Chapter IV are directed toward the development of a platinum(II)-catalyzed oxidative alkane dehydrogenation. Stoichiometric conversion of alkanes (cyclohexane, ethane) to olefins (cyclohexene, ethylene) is achieved by C-H activation with [(N-N)Pt(CH_3)(CF_3CH_2OH)]BF_4 (1, N-N is N,N'-bis(3,5-di-t- butylphenyl)-1,4-diazabutadiene) which results in the formation of olefin hydride complexes. The first step in the C-H activation reaction is formation of a platinum(II) alkyl which undergoes β-hydrogen elimination to afford the olefin hydride complex. The cationic ethylplatinum(II) intermediate can be generated in situ by treating diethylplatinum(II) compounds with acids. Treatment of (phen)PtEt_2 with [H(OEt_2)_2]Bar^f_4 at low temperatures resulted in the formation of a mixture of [(phen)PtEt(OEt_2)]Bar^f_4 (8) and [(phen)Pt(C_2H_4)H] Bar^f_4 (7). The cationic olefin complexes are unreactive toward dioxygen or hydrogen peroxide. Since the success of the overall catalytic cycle depends on our ability to oxidize the olefin hydride complexes, a series of neutral olefin complexes of platinum(II) with monoanionic ligands (derivatives of pyrrole-2-carboxyaldehyde N-aryl imines) was prepared. Unfortunately, these are also stable to oxidation.