- Norman, Oklahoma, United States
- Chemistry, Entrepreneurship, Nanotechnology, Energy, Catalysis, Chemical Engineering, and 12 moreHeterogeneous Catalysis, Petroleum refining and petrochemicals, Surfactant Science & Technology, Mesoporous Materials, Zeolites, Fluid Catalytic Cracking, Zeolite Y, Engineering, Biomass to fuel conversion, Environmental Sustainability, Materials Chemistry, and Nanoparticlesedit
- Professor of Chemical Engineering at University of Oklahoma, PhD Yale 1983.edit
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Bladder cancer has a 60%-70% recurrence rate most likely due to any residual tumour left behind after a transurethral resection (TUR). Failure to completely resect the cancer can lead to recurrence and progression into higher grade... more
Bladder cancer has a 60%-70% recurrence rate most likely due to any residual tumour left behind after a transurethral resection (TUR). Failure to completely resect the cancer can lead to recurrence and progression into higher grade tumours with metastatic potential. We present here a novel therapy to treat superficial tumours with the potential to decrease recurrence. The therapy is a heat-based approach in which bladder tumour specific single-walled carbon nanotubes (SWCNTs) are delivered intravesically at a very low dose (0.1 mg SWCNT per kg body weight) followed 24 h later by a short 30 s treatment with a 360° near-infrared light that heats only the bound nanotubes. The energy density of the treatment was 50 J cm-2, and the power density that this treatment corresponds to is 1.7 W cm-2, which is relatively low. Nanotubes are specifically targeted to the tumour via the interaction of annexin V (AV) and phosphatidylserine, which is normally internalised on healthy tissue but externalised on tumours and the tumour vasculature. SWCNTs are conjugated to AV, which binds specifically to bladder cancer cells as confirmed in vitro and in vivo. Due to this specific localisation, NIR light can be used to heat the tumour while conserving the healthy bladder wall. In a short-term efficacy study in mice with orthotopic MB49 murine bladder tumours treated with the SWCNT-AV conjugate and NIR light, no tumours were visible on the bladder wall 24 h after NIR light treatment, and there was no damage to the bladder. In a separate survival study in mice with the same type of orthotopic tumours, there was a 50% cure rate at 116 days when the study was ended. At 116 days, no treatment toxicity was observed, and no nanotubes were detected in the clearance organs or bladder.
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The high prevalence of breast cancer is a global health concern, but there are no safe or effective treatments for it at its advanced stages. These facts urge the development of novel treatment strategies. Annexin A5 (ANXA5) is a natural... more
The high prevalence of breast cancer is a global health concern, but there are no safe or effective treatments for it at its advanced stages. These facts urge the development of novel treatment strategies. Annexin A5 (ANXA5) is a natural human protein that binds with high specificity to phosphatidylserine, a phospholipid tightly maintained in the inner leaflet of the cell membrane on most healthy cells but externalized in tumor cells and the tumor vasculature. Here, we have developed a targeted photosensitizer for photothermal therapy (PTT) of solid tumors through the functionalization of single walled carbon nanotubes (SWCNTs) to ANXA5—the SWCNT-ANXA5 conjugate. The ablation of tumors through the SWCNT-ANXA5-mediated PTT synergizes with checkpoint inhibition, creating a systemic anti-cancer immune response. In vitro ablation of cells incubated with the conjugate promoted cell death in a dose-dependent and targeted manner. This treatment strategy was tested in vivo with the orthoto...
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The bonding configuration and the heat of adsorption<br> of a furfural molecule on the Pd(111) surface were determined by ab<br> initio density-functional-theory calculations. The dynamics of pure<br> liquid water, the... more
The bonding configuration and the heat of adsorption<br> of a furfural molecule on the Pd(111) surface were determined by ab<br> initio density-functional-theory calculations. The dynamics of pure<br> liquid water, the liquid-solid interface formed by liquid water and the<br> Pd(111) surface, as well as furfural at the water-Pd interface, were<br> investigated by ab initio molecular dynamics simulations at finite<br> temperatures. Calculations and simulations suggest that the bonding<br> configurations at the water-Pd interface promote decarbonylation of<br> furfural.
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Abstract The effect of support type (SiO2, CeO2, ZrO2, TiO2, Nb2O5) on the removal of the different oxygenated functional groups (hydroxyl and methoxy) was investigated in the hydrodeoxygenation (HDO) of guaiacol over supported Pd... more
Abstract The effect of support type (SiO2, CeO2, ZrO2, TiO2, Nb2O5) on the removal of the different oxygenated functional groups (hydroxyl and methoxy) was investigated in the hydrodeoxygenation (HDO) of guaiacol over supported Pd catalysts at 573 K and atmospheric pressure. The product distribution depended on the support type, and three main reaction pathways were proposed: demethoxylation, demethylation and dehydroxylation. Demethoxylation yielding phenol was the dominant reaction pathway over all catalysts with only a minor contribution from the demethylation reaction taking place. However, significant dehydroxylation reaction was still observed for the catalysts having Pd supported on ZrO2, TiO2 and Nb2O5. Further conversion of phenol to cylohexanone was favored over SiO2 and CeO2-based catalysts, while benzene was only detected over ZrO2, TiO2 and Nb2O5, which is due to the presence of oxophilic cations. DRIFTS measurements were carried out to evaluate the adsorption mode and strength of guaiacol on the catalyst surface. The functional groups involved in adsorption of guaiacol included both hydroxyl and methoxy groups. At the reaction conditions, the hydroxyl group is strongly adsorbed to the catalyst surface and may block the catalytic sites, thus inhibiting further conversion of phenol and resulting in lower deoxygenation rates.
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This work investigates the correlation of the reaction conditions and the reaction medium composition with the deactivation behavior of a Ni/La2O3-αAl2O3 catalyst used in the steam reforming of bio-oil.
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This work studies the effect of zirconia structure on the performance of Pd/ZrO2 catalysts for hydrodeoxygenation of phenol at 300 °C and 1 atm using a fixed bed reactor. Benzene was the major product over Pd/t-ZrO2, while significant... more
This work studies the effect of zirconia structure on the performance of Pd/ZrO2 catalysts for hydrodeoxygenation of phenol at 300 °C and 1 atm using a fixed bed reactor. Benzene was the major product over Pd/t-ZrO2, while significant formation of cyclohexanone was observed over Pd/m-ZrO2. On the other hand, Pd/m,t-ZrO2 exhibited intermediary behavior. DRIFTS of adsorbed pyridine, NH3-TPD, and the dehydration of the cyclohexanol reaction revealed that the Pd/t-ZrO2 catalyst exhibits a higher density of oxophilic sites than Pd/m-ZrO2 and Pd/m,t-ZrO2. This promoted the formation of deoxygenated products. However, a mechanism involving dehydration of cyclohexanol to cyclohexene, followed by dehydrogenation to benzene, may not be ruled out. Pd/ZrO2 catalysts significantly deactivated as a function of time on stream. Results of dehydrogenation of cyclohexane and dehydration of cyclohexanol indicate that the Pd particle size increased and the density of oxophilic sites decreased during the hydrodeoxygenation of...
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Research Interests: Chemical Engineering, Chemistry, Catalysis, Zeolite, Metal, and 3 morePalladium, Alkylation, and Selectivity
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ABSTRACT The main objective of the present work was the study of different ZSM-5 catalytic formulations for the in situ upgrading of biomass pyrolysis vapors. An equilibrium, commercial diluted ZSM-5 catalyst was used as the base case, in... more
ABSTRACT The main objective of the present work was the study of different ZSM-5 catalytic formulations for the in situ upgrading of biomass pyrolysis vapors. An equilibrium, commercial diluted ZSM-5 catalyst was used as the base case, in comparison with a series of nickel (Ni) and cobalt (Co) modified variants at varying metal loading (1–10 wt.%). The product yields and the composition of the produced bio-oil were significantly affected by the use of all ZSM-5 catalytic materials, compared to the non-catalytic flash pyrolysis, producing less bio-oil but of better quality. Incorporation of transition metals (Ni or Co) in the commercial equilibrium/diluted ZSM-5 catalyst had an additional effect on the performance of the parent ZSM-5 catalyst, with respect to product yields and bio-oil composition, with the NiO modified catalysts being more reactive towards decreasing the organic phase and increasing the gaseous products, compared to the Co3O4 supported catalysts. However, all the metal-modified catalysts exhibited limited reactivity towards water production, while simultaneously enhancing the production of aromatics and phenols. An interesting observation was the in situ reduction of the supported metal oxides during the pyrolysis reaction that eventually led to the formation of metallic Ni and Co species on the catalysts after reaction, which was verified by detailed XRD and HRTEM analysis of the used catalysts. The Co3O4 supported ZSM-5 catalysts exhibited also a promising performance in lowering the oxygen content of the organic phase of bio-oil.
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This paper describes the objectives, methods and early results on the US Department of Energy sponsored project to generate hydrogen from splitting of water using photocatalysts. The approach uses organometallic photosensitizers adsorbed... more
This paper describes the objectives, methods and early results on the US Department of Energy sponsored project to generate hydrogen from splitting of water using photocatalysts. The approach uses organometallic photosensitizers adsorbed onto platinated titania. Platinized titania is a photocatalyst for water splitting, but does not absorb sunlight in the visible range, where most of the sun`s energy is contained. Organometallic photosensitizers are synthesized, attached to platinized titania and characterized by UV-Vis spectroscopy, cyclic voltammetry, action spectra and hydrogen generation ability. Thus far, Copper, Iron and Ruthenium catalyst systems have been produced and characterized in this manner. Suitable sensitized systems that have the desirable properties have not yet been found.
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Renewed interest in zeolite catalyst performance in the presence of variable amounts of water has prompted solid-state NMR experiments designed to identify the nature of water interaction with and within conventional and chemically... more
Renewed interest in zeolite catalyst performance in the presence of variable amounts of water has prompted solid-state NMR experiments designed to identify the nature of water interaction with and within conventional and chemically modified H-ZSM-5 zeolites. Recent work has demonstrated that water can positively influence reaction rates in zeolite-catalyzed chemistries, and new interest in catalytic processing of molecules derived from biomass requires understanding the fate of water in and on zeolite catalysts, as a function of water loading. The contribution of acid site density to water adsorption within zeolites is assessed by comparing bulk uptake and molecular experiments at varying Si:Al ratios, and interpreting those results in the context of solid-state NMR results that reveal strongly adsorbed water molecules and water clusters. In situ magic-angle spinning (MAS) NMR experiments for water loadings ranging from ca. 4 to 500 water molecules per zeolite unit cell indicate the following: (1) the dom...
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The strong interaction between Pd2+ and ethylenediamine (en), within the confinement of MIL-101(Cr), effectively prevented the reduction of Pd2+ by the feed and minimized leaching of the active Pd2+ species under oxidizing and acidic... more
The strong interaction between Pd2+ and ethylenediamine (en), within the confinement of MIL-101(Cr), effectively prevented the reduction of Pd2+ by the feed and minimized leaching of the active Pd2+ species under oxidizing and acidic conditions.
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Research Interests: Engineering, Chemistry, Technology, Catalysis, Phosphorus, and 3 moreZeolite, CHEMICAL SCIENCES, and Phosphate
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This presentation highlights recent advances by the Center for Interfacial Reaction Engineering (CIRE) in designing and tailoring catalytic particles for use in phase-transfer catalysis. CIRE consists of researchers across several... more
This presentation highlights recent advances by the Center for Interfacial Reaction Engineering (CIRE) in designing and tailoring catalytic particles for use in phase-transfer catalysis. CIRE consists of researchers across several disciplines including nanotechnology, thermodynamics, interfacial phenomena, and catalysis from three different universities. The results highlight the importance of particle wetting on dynamic interfacial and overall emulsion behavior and has potential importance for a variety of applications in the biofuels, pharmaceuticals, and energy sectors.
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We report a reaction platform for the synthesis of three different high‐value specialty chemical building blocks starting from bio‐ethanol, which might have an important impact in the implementation of biorefineries. First, oxidative... more
We report a reaction platform for the synthesis of three different high‐value specialty chemical building blocks starting from bio‐ethanol, which might have an important impact in the implementation of biorefineries. First, oxidative dehydrogenation of ethanol to acetaldehyde generates an aldehyde‐containing stream active for the production of C4 aldehydes via base‐catalyzed aldol‐condensation. Then, the resulting C4 adduct is selectively converted into crotonic acid via catalytic aerobic oxidation (62 % yield). Using a sequential epoxidation and hydrogenation of crotonic acid leads to 29 % yield of β‐hydroxy acid (3‐hydroxybutanoic acid). By controlling the pH of the reaction media, it is possible to hydrolyze the oxirane moiety leading to 21 % yield of α,β‐dihydroxy acid (2,3‐dihydroxybutanoic acid). Crotonic acid, 3‐hydroxybutanoic acid, and 2,3‐dihydroxybutanoic acid are archetypal specialty chemicals used in the synthesis of polyvinyl‐co‐unsaturated acids resins, pharmaceutics,...
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In this study, a modified filtration equation that accounts for the transport and kinetics of polymer‐coated multiwalled carbon nanotubes in columns packed with crushed Berea sandstone is presented. The columns were saturated with brine... more
In this study, a modified filtration equation that accounts for the transport and kinetics of polymer‐coated multiwalled carbon nanotubes in columns packed with crushed Berea sandstone is presented. The columns were saturated with brine solution, in which the salt concentration was varied from 0 to 10 wt%. Experimental results show that the polymer effectively eliminates the effects of salt on particle deposition when the salt concentration is less than or equal to 10 wt%. The calculated cumulative particle recovery is as high as 88.47 ± 0.25%. Results show that, at 10 wt% salt concentration, the proposed equation successfully predicts the experimental behavior, especially at the early stages of the breakthrough, where commonly used models fail. It is argued that the new equation accounts for the dynamic change of single collector efficiency as the deposition process advances. When tested against prior results available in the literature, the proposed model agrees with published dat...