Target-Oriented Content and Sentiment Analysis

Target-oriented analysis aims at mining the targeted information towards specified targets (objects of users' interest). There are many real-world tasks in the data mining and natural language processing (NLP) areas. This thesis focuses on two specific tasks, target-oriented content analysis, and target-oriented sentiment analysis. The first task is to generate target-specific topics for focused analysis, which is also quite helpful not only for computer science but also health science and social science. For this task, we developed a new target-focused generative model, which can distill the topics relevant to the given target. The second task is to infer the target-specific sentiment in review data. We proposed several alternative target-sensitive supervised learning solutions. Empirical results demonstrate the effectiveness of our approaches for both tasks. My further works on these two tasks are to use the idea of lifelong machine learning (LML) for performance enhancement. The intuition is that, when a system/learner performs tasks continuously, we want it to utilize the knowledge obtained from the past to help future tasks. To achieve this goal, we proposed two lifelong learning models for content analysis and sentiment analysis respectively. Experimental results show the usefulness of the LML solutions for both tasks

Glucose diffusivity and spreading experiments with porous scaffolds and membranes for tissue engineering bioreactors

Glucose diffusivity and spreading experiments with porous scaffolds and membranes for tissue engineering bioreactor

Modulation of Estrogen Oxidative Metabolism by Botanicals (Hops and Licorice) Used for Women’s Health

Estrogen is the primary hormone in women that plays an important role in maintaining normal functions of various tissues and organs. However, elongated exposure to estrogen from the use of hormone therapy has been found to be a risk factor for breast cancer carcinogenesis. Consequently, botanical dietary supplements are more and more being used by women as a surrogate for hormone therapy. Neither safety, efficacy, nor standardization is required prior to the marketing of these botanical dietary supplements. In this study, botanical extract as well as botanical pure compounds were evaluated for their effects on estrogen chemical carcinogenesis. Estrogen chemical carcinogenesis involves 4-hydroxylation of estrogens by P450 1B1, generating catechol and quinone genotoxic metabolites that cause DNA mutations and initiate/promote breast cancer. A LC-MS/MS assay was employed to quantify estrogen metabolism by measuring 2-MeOE1 as non-toxic and 4-MeOE1 as genotoxic biomarkers in the human mammary epithelial cell lines. P450 1A1 and 1B1 enzyme activity and expression was measured and upstream aryl hydrocarbon receptor activation tested to explore the mechanisms. Two commonly used botanical extract licorice and hops were shown to have beneficial activity in modulating estrogen oxidative metabolism to potentially lower the risk of breast cancer. Bioactive compounds licochalcone A and 6-prenylnaringenin from these botanical extracts were identified to contribute to the activity of the extracts. Results from this study can be used to help standardize botanical dietary supplements with better safety and reproducible biological outcomes

Mechanism of Isobutanal–Isobutene Prins Condensation Reactions on Solid Brønsted Acids

The selectivity to 2,5-dimethyl-hexadiene isomers (2,5-DMH) via acid-catalyzed isobutanal–isobutene Prins condensation is limited by isobutene oligomerization reactions (to 2,4,4-trimethyl-pentene isomers) and by skeletal isomerization and cyclization of the primary 2,5-DMH products of Prins condensation. Experiment and theory are used here to assess and interpret acid strength effects on the reactivity and selectivity for isobutanal–isobutene Prins condensation routes to 2,5-DMH, useful as precursors to <i>p</i>-xylene. Non-coordinating 2,6-di-<i>tert</i>-butylpyridine titrants fully suppress reactivity on Keggin heteropolyacids, niobic acid, and mesoporous and microporous aluminosilicates, indicating that Prins condensation, parallel isobutene oligomerization, and secondary skeletal isomerization and cyclization of primary 2,5-DMH products occur exclusively on Brønsted acid sites. The number of titrants required to suppress rates allows site counts for active protons, a requirement for comparing reactivity among solid acids as turnover rates, as well as for the rigorous benchmarking of mechanistic proposals by theory and experiment. Kinetic and theoretical treatments show that both reactions involve kinetically relevant C–C bond formation elementary steps mediated by cationic C–C coupling transition states. Transition state charges increase with increasing acid strength for Prins condensation, becoming full carbenium-ions only on the stronger acids. Oligomerization transition state structures, in contrast, remain full ion-pairs, irrespective of acid strength. Turnover rates for both reactions increase with acid strength, but oligomerization transition states preferentially benefit from the greater stability of the conjugate anions in the stronger acids, leading to higher 2,5-DMH selectivities on weaker acids (niobic acid, aluminosilicates). These trends and findings are consistent with theoretical estimates of activation free energies for Prins condensation and oligomerization elementary steps on aluminosilicate slab and Keggin heteropolyacid cluster models. High 2,5-DMH selectivities require weak acids, which do not form a full ion-pair at transition states and thus benefit from significant stabilization by residual covalency. These trends demonstrate the previously unrecognized consequences of incomplete proton transfer at oxygen-containing transition states in dampening the effects of acid strength, which contrast the full ion-pair transition states and stronger acid strength effects in hydrocarbon rearrangements on solids acids of catalytic relevance. These mechanistic conclusions and the specific example used to illustrate them led us to conclude that reaction routes involving O-containing molecules become prevalent over hydrocarbon rearrangements on weak acids when parallel routes are accessible in mixtures of oxygenate and hydrocarbon reactants

Experimental and Theoretical Evidence for the Reactivity of Bound Intermediates in Ketonization of Carboxylic Acids and Consequences of Acid–Base Properties of Oxide Catalysts

Ketonization of carboxylic acids on metal oxides enables oxygen removal and the formation of new C–C bonds for increasing the energy density and chemical value of biomass-derived streams. Information about the surface coverages and reactivity of various bound species derived from acid reactants and the kinetic relevance of the elementary steps that activate reactants, form C–C bonds, and remove O atoms and how they depend on acid–base properties of surfaces and molecular properties of reactants is required to extend the range of ketonization catalytic practice. Here, we examine such matters for ketonization of C₂–C₄ carboxylic acids on monoclinic and tetragonal ZrO₂ (ZrO₂(m), ZrO₂(t)) materials that are among the most active and widely used ketonization catalysts by combining kinetic, isotopic, spectroscopic, and theoretical methods. Ketonization turnovers require Zr–O acid–base pairs, and rates, normalized by the number of active sites determined by titration methods during catalysis, are slightly higher on ZrO₂(m) than ZrO₂(t), but exhibit similar kinetic dependence and the essential absence of isotope effects. These rates and isotope effects are consistent with surfaces nearly saturated with acid-derived species and with kinetically limited C–C bond formation steps involving 1-hydroxy enolates formed via α-C–H cleavage in bound carboxylates and coadsorbed acids; these mechanistic conclusions, but not the magnitude of the rate parameters, are similar to those on anatase TiO₂ (TiO₂(a)). The forms of bound carboxylic acids at Zr–O pairs become more stable and evolve from molecular acids to dissociated carboxylates as the combined acid and base strength of the Zr and O centers at each type of site pair increases; these binding properties are estimated from DFT-derived NH₃ and BF₃ affinities. Infrared spectra during ketonization catalysis show that molecularly bound acids and monodentate and bidentate carboxylates coexist on ZrO₂(m) because of diversity of Zr–O site pairs that prevails on such surfaces, distinct in coordination and consequently in acid and base strengths, and that monodentate and bidentate carboxylates are the most abundant species on saturated ZrO₂ surfaces, consistent with their DFT-derived binding strengths. Theoretical assessments of free energies along the reaction coordinate show that monodentate carboxylates act as precursors to reactive 1-hydroxy enolate intermediates, while strongly bound bidentate carboxylates are unreactive spectators. Higher 1-hydroxy enolate coverages, brought forth by stabilization on the more strongly basic O sites on ZrO₂(m), account for the more reactive nature of ZrO₂(m) than TiO₂(a). These findings indicate that the elementary steps and site requirements for ketonization of C₂–C₄ carboxylic acids are similar on M–O site pairs at TiO₂ and ZrO₂ surfaces, a conclusion that seems general to other metal oxides of comparable acid–base strength

In Situ Observation of the Growth of ZnO Nanostructures Using Liquid Cell Electron Microscopy

Understanding the growth mechanisms and associated kinetics is a fundamental issue toward the specific function-oriented controlled synthesis of nanostructures. In this work, the growth of zinc oxide nanostructures with different sizes and morphologies are directly observed by in situ liquid-cell transmission electron microscopy (TEM). Real-time observation and quantitative analysis reveal that the concentration ratios of the precursors are responsible for the different growth kinetics, resulting in different morphology and size of the synthesized ZnO nanostructures

Selective Hydrogenolysis of Glycerol to Propylene Glycol on Supported Pd Catalysts: Promoting Effects of ZnO and Mechanistic Assessment of Active PdZn Alloy Surfaces

Pd catalysts have received increasing attention for selective hydrogenolysis of glycerol to propylene glycol because of their good hydrothermal stability and high selectivity for cleavage of C–O bonds over C–C bonds. Addition of Zn can facilitate glycerol hydrogenolysis to propylene glycol on Pd surface, but the promoting role of Zn, stability of the resulting active PdZn alloys and reaction mechanism remain largely unexplored. Here, we synthesized monoclinic zirconia-supported PdZn (PdZn/m-ZrO₂) catalysts via an incipient wetness impregnation method. Glycerol hydrogenolysis turnover rates (normalized per surface Pd atom measured by H₂ chemisorption) and propylene glycol selectivity on these PdZn/m-ZrO₂ catalysts depended sensitively on their Zn/Pd molar ratios, and Zn leaching from the PdZn alloy phases led to deactivation of PdZn/m-ZrO₂. Such deactivation was efficiently inhibited when physical mixtures of Pd/m-ZrO₂ and ZnO were directly used in glycerol hydrogenolysis, leading to in situ formation of PdZn alloy layers on Pd surfaces with excellent stability and recyclability. Dependence of turnover rates on glycerol and H₂ concentrations, combined with the primary kinetic isotope effects (<i>k</i>_H<i>/k</i>_D = 2.6 at 493 K), reveals the kinetically relevant step of glycerol hydrogenolysis involving the α-C-H cleavage in 2,3-dihydroxypropanoxide intermediate to glyceraldehyde on PdZn alloys and Pd. Measured rate constants show that the transition state of α-C-H cleavage is more stable because of the stronger oxophilicity of Zn on PdZn alloys than on Pd, which thus facilitates α-C-H cleavage of the Zn-bound intermediate by adjacent Pd on PdZn alloys. Such synergy between Zn and Pd sites accounts for the observed superiority of PdZn alloys to Pd in glycerol hydrogenolysis

Syntheses, molecular structures, and self-assemblies of SFe₃, S₂Fe₃, S₃Fe₅, SeFe₃, and Se₂Fe₃ clusters with chelating diaminocarbenes

<div><p>The reactions of substituted thioureas and selenoureas with iron carbonyls have been systematically investigated, and five types of SFe₃, S₂Fe₃, S₃Fe₅, SeFe₃, and Se₂Fe₃ clusters with chelating diaminocarbenes have been synthesized and characterized by X-ray crystallography. The reactions of C₃H₅NHC(=S)NHAr with Fe₃(CO)₁₂ afford (μ₃-S)Fe₃(CO)₇(μ-CO)(κ³<i>C</i>,<i>C</i>,<i>C</i>-C₃H₅NHCNHAr) (<b>1</b>, Ar = Ph; <b>2</b>, Ar = 4-H₂NC₆H₄). In contrast, the reactions of (2-C₅H₄N)NHC(=S)NHN=CHAr with Fe₂(CO)₉ form (μ₃-S)₂Fe₃(CO)₇(κ²<i>N</i>,<i>C</i>-(2-C₅H₄N)NHCNHN=CHAr) (<b>3</b>, Ar = Ph; <b>4</b>, Ar = 4-CH₃C₆H₄). Likewise, reactions of GNHC(=S)NHC(=O)Ph with Fe₃(CO)₁₂ provide (μ₃-S)₂Fe₃(CO)₇(κ²<i>N</i>,<i>C</i>-GNHCNHC(=O)Ph) (<b>5</b>, G = 2-C₅H₄N; <b>6</b>, G = 2-C₄H₃N₂) as well as Fe₃(CO)₈(μ-CO)₂(κ²<i>N</i>,<i>C</i>-(2-C₄H₃N₂)NHCNHC(=O)Ph). The reaction of (2-C₅H₄N)NHC(=S)NH₂ with Fe₃(CO)₁₂ gives (μ₃-S)₂Fe₃(CO)₇(κ²<i>N</i>,<i>C</i>-(2-C₅H₄N)NHCNH₂) (<b>7</b>). The reactions of GNHC(=S)NHPh with Fe₃(CO)₁₂ produce (μ₃-S)₂Fe₃(CO)₇(κ²<i>N</i>,<i>C</i>-GNHCNHPh) (<b>8</b>, G = 2-C₅H₄N; <b>9</b>, G = 2-C₄H₃N₂). Analogously, (2-C₅H₄N)NHC(=S)NH(2-CH₃C₆H₄) offers (μ₃-S)₂Fe₃(CO)₇(κ²<i>N</i>,<i>C</i>-(2-C₅H₄N)NHCNH(2-CH₃C₆H₄)) (<b>10</b>). However, (2-C₅H₄N)NHC(=S)NH(2-CH₃OC₆H₄) generates (μ₃-S)₂(μ₄-S)Fe₅(CO)₁₀(μ-CO)₂(κ²<i>N</i>,<i>C</i>-(2-C₅H₄N)NHCNH(2-CH₃OC₆H₄)) (<b>11</b>). Furthermore, the reactions of (2-C₅H₄N)NHC(=S)NHR with Fe₃(CO)₁₂ form (μ₃-S)₂(μ₄-S)Fe₅(CO)₁₀(μ-CO)₂(κ²<i>N</i>,<i>C</i>-(2-C₅H₄N)NHCNHR) (<b>12</b>, R = 2-H₂NC₆H₄; <b>13</b>, R = 4-H₂NC₆H₄; <b>14</b>, R = 2-C₅H₄N). Surprisingly, the reaction of (2-C₅H₄N)NHC(=S)NHC₃H₅ with Fe₃(CO)₁₂ leads to (μ₃-S)₂(μ₄-S)Fe₅(CO)₁₀(μ-CO)₂(κ²<i>N</i>,<i>C</i>-(2-C₅H₄N)NHCNHC₃H₅) (<b>15</b>). The reaction of C₃H₅NHC(=Se)NHPh with Fe₃(CO)₁₂ affords (μ₃-Se)Fe₃(CO)₇(μ-CO)(κ³<i>C</i>,<i>C</i>,<i>C</i>-C₃H₅NHCNHPh) (<b>16</b>) as well as [(κ²<i>N</i>,<i>C</i>-PhNCNHC₃H₅)Fe₂(CO)₆(μ₄-Se)Fe₂(CO)₆]₂(μ₄-Se). As with (2-C₄H₃N₂)NHC(=S)NHPh, (2-C₄H₃N₂)NHC(=Se)NHPh offers (μ₃-Se)₂Fe₃(CO)₇(κ²<i>N</i>,<i>C</i>-(2-C₄H₃N₂)NHCNHPh) (<b>17</b>). Unlike (2-C₅H₄N)NHC(=S)NH(2-CH₃OC₆H₄), (2-C₅H₄N)NHC(=Se)NH(2-CH₃OC₆H₄) yields (μ₃-Se)₂Fe₃(CO)₇(κ²<i>N</i>,<i>C</i>-(2-C₅H₄N)NHCNH(2-CH₃OC₆H₄)) (<b>18</b>). By virtue of N–HN, N–HO, and C–HO intermolecular hydrogen bonds along with other non-covalent interactions, these new organometallic clusters exhibit interesting supramolecular structures.</p></div

Schematic diagram of boundary adjustment section of open pit mines.

(a)Open pit limit adjustment of the near level coal seam. (b)Adjustment of open pit limit in inclined coal seam.</p

Sliding window method to determine optimal mining boundary.

Sliding window method to determine optimal mining boundary.</p