Publications

2017
W. F. Woodruff, Lewan, M. D., Revil, A., and Torres-Verdín, C., “Complex electrical conductivity changes associated with hydrous pyrolysis maturation of the Woodford Shale.,” Geophysics, vol. 82, no. 2, pp. D83-D104, 2017.
W. F. Woodruff, Lewan, M. D., Revil, A., and Torres-Verdín, C., “Complex electrical conductivity changes associated with hydrous pyrolysis maturation of the Woodford Shale.,” Geophysics, vol. 82, no. 2, pp. D83-D104, 2017.
T. Cantu, Walsh, K., Pattani, V. P., Moy, A. J., Tunnell, J. W., Irvin, J. A., and Betancourt, T., “Conductive polymer-based nanoparticles for laser-mediated photothermal ablation of cancer: synthesis, characterization, and in vitro evaluation,” Int J Nanomedicine, vol. 12, pp. 615-632, 2017.Abstract
Laser-mediated photothermal ablation of cancer cells aided by photothermal agents is a promising strategy for localized, externally controlled cancer treatment. We report the synthesis, characterization, and in vitro evaluation of conductive polymeric nanoparticles (CPNPs) of poly(diethyl-4,4'-[2,5-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-1,4-phenyle ne] bis(oxy)dibutanoate) (P1) and poly(3,4-ethylenedioxythiophene) (PEDOT) stabilized with 4-dodecylbenzenesulfonic acid and poly(4-styrenesulfonic acid-co-maleic acid) as photothermal ablation agents. The nanoparticles were prepared by oxidative-emulsion polymerization, yielding stable aqueous suspensions of spherical particles of <100 nm diameter as determined by dynamic light scattering and electron microscopy. Both types of nanoparticles show strong absorption of light in the near infrared region, with absorption peaks at 780 nm for P1 and 750 nm for PEDOT, as well as high photothermal conversion efficiencies ( 50%), that is higher than commercially available gold-based photothermal ablation agents. The nanoparticles show significant photostability as determined by their ability to achieve consistent temperatures and to maintain their morphology upon repeated cycles of laser irradiation. In vitro studies in MDA-MB-231 breast cancer cells demonstrate the cytocompatibility of the CPNPs and their ability to mediate complete cancer cell ablation upon irradiation with an 808-nm laser, thereby establishing the potential of these systems as agents for laser-induced photothermal therapy.
B. J. Dear, Hung, J. J., Truskett, T. M., and Johnston, K. P., “Contrasting the Influence of Cationic Amino Acids on the Viscosity and Stability of a Highly Concentrated Monoclonal Antibody,” Pharmaceutical Research, vol. 34, no. 1, pp. 193-207, 2017. Publisher's VersionAbstract
Purpose To explain the effects of cationic amino acids and other co-solutes on the viscosity, stability and protein-protein interactions (PPI) of highly concentrated (≥200 mg/ml) monoclonal antibody (mAb) solutions to advance subcutaneous injection. Methods The viscosities of ≥200 mg/ml mAb1 solutions with various co-solutes and pH were measured by capillary rheometry in some cases up to 70,000 s−1. The viscosities are analyzed in terms of dilute PPI characterized by diffusion interaction parameters (kD) from dynamic light scattering (DLS). MAb stability was measured by turbidity and size exclusion chromatography (SEC) after 4 weeks of 40°C storage. Results Viscosity reductions were achieved by reducing the pH, or adding histidine, arginine, imidazole or camphorsulfonic acid, each of which contains a hydrophobic moiety. The addition of inorganic electrolytes or neutral osmolytes only weakly affected viscosity. Systems with reduced viscosities also tended to be Newtonian, while more viscous systems were shear thinning. Conclusions Viscosity reduction down to 20 cP at 220 mg/ml mAb1 was achieved with co-solutes that are both charged and contain a hydrophobic interaction domain for sufficient binding to the protein surface. These reductions are related to the DLS diffusion interaction parameter, kD, only after normalization to remove the effect of charge screening. Shear rate profiles demonstrate that select co-solutes reduce protein network formation.
E. Bakolas, “Covariance Control for Discrete-Time Stochastic Linear Systems with
Incomplete State Information
,” American Control Conference. Seattle, WA, 2017.PDF icon eb_acc_2017.pdf
Z. Li, Bauers, S. R., Poudel, N., Hamann, D., Wang, X., Choi, D. S., Esfarjani, K., Shi, L., Johnson, D. C., and Cronin, S. B., “Cross-Plane Seebeck Coefficient Measurement of Misfit Layered Compounds (SnSe)n(TiSe2)n (n = 1,3,4,5),” Nano Letters, vol. 17, pp. 1978–1986 , 2017. Publisher's Version
N. Poudel, Liang, S. - J., Choi, D., Hou, B., Shen, L., Shi, H., Ang, L. K., Shi, L., and Cronin, S., “Cross-plane Thermoelectric and Thermionic Transport across Au/h-BN/Graphene Heterostructures,” Scientific Reports, vol. 7, pp. 14148, 2017. Publisher's Version
M. R. Tucker, Shirota, C., Lambercy, O., Sulzer, J. S., and Gassert, R., “Design and characterization of an exoskeleton for perturbing the knee during gait,” IEEE Transactions on Biomedical Engineering, vol. 64, no. 10, pp. 2331-2343, 2017.
R. Edupuganti, Taliaferro, J. M., Wang, Q., Xie, X., Cho, E. J., Vidhu, F., Ren, P., Anslyn, E. V., Bartholomeusz, C., and Dalby, K. N., “Discovery of a potent inhibitor of MELK that inhibits expression of the anti-apoptotic protein Mcl-1 and TNBC cell growth,” Bioorganic & Medicinal Chemistry, vol. 25, no. 9, pp. 2609-2616, 2017.
S. Misra, Torres-Verdín, C., Homan, D., and Rasmus, J., “Dispersive and directional effective electrical conductivity and dielectric permittivity of conductive-mineral-bearing samples derived from multi-frequency tensor electromagnetic induction measurements,” Geophysics, vol. 82, no. 4, pp. D211-D223, 2017.
C. E. Tinney, Hill, B., Valdez, J., Sirohi, J., and Cameron, C., “Drone acoustics at static thrust conditions,” American Helicopgter Society 73rd Annual Forum. Fort Worth, Texas, USA, 2017.Abstract
Multirotor drones are becoming increasingly popular in both the civilian and military sectors of our society. These compact gadgets come in a variety of sizes with the smallest ones measuring less than two inches in diameter, while larger ones can be in excess of five feet. Surprisingly, very little is known about their acoustical footprint, which is becoming a topic of broad importance given that these vehicles most often operate in populated areas. Thus, the objective of this paper is to provide a first principles understanding of the acoustical characteristics of hovering drones. To accomplish this, a new test stand was constructed at the Applied Research Laboratories at The University of Texas at Austin for studying various multirotor drone configurations. The drone test stand is capable of powering up to eight DC electric motors with adjustable arms that allow different rotor diameters to be tested. Rotor diameters ranging from 8 in to 12 in are studied and with configurations comprised of an isolated rotor, a quadcopter configuration and a hexacopter configuration. A six degree-of-freedom load cell is used to assess the aerodynamic performance of each drone configuration. Meanwhile, an azimuthal array of 1/2-inch microphones is placed between 2 and 3 hub-center diameters from the drone center thereby allowing the acoustic near-field to be quantified. The analysis is performed using standard statistical metrics such as Sound Pressure Level and Overall Sound Pressure Level and is presented to demonstrate the relationship between the number of rotors, the drone rotor size and it’s aerodynamic performance (thrust) relative to the far-field noise.
C. E. Tinney, Scott, K., Routon, M., Sirohi, J., and Ruf, J., “Effect of aeroelasticity on vibroacoustic loads during startup of large area ratio nozzles,” 23rd AIAA/CEAS Aeroacoustics Conference. Denver, Colorado, USA, 2017.Abstract
The vibroacoustic loads that form during the startup of both rigid and compliant wallhigh area ratio nozzles is investigated. The rigid wall nozzle is fabricated from 6061 aluminum while the compliant wall nozzles are formed from urethane-based elastomers in orderto invoke aeroelastic coupling between the nozzle wall and the internal flow. Single pointmeasurements of the nozzle lip displacement are synchronized with a pressure field microphone located behind the nozzle where the base of a vehicle would reside. Particularattention is drawn to the sound field during transition from free-shock separated flow torestricted shock separated flow, as well as the end-effects regime loads. The findings revealthe sensitivity of the vibroacoustic loads to the aeroelasticity of the nozzle wall duringcritical stages in the startup process.
P. Sayar and Torres-Verdín, C., “Effective-medium modeling of velocity dispersion and attenuation in isotropic rocks.,” Geophysics, vol. 82, no. 2, pp. D133-D154, 2017.
P. Sayar and Torres-Verdín, C., “Effective-medium modeling of velocity dispersion and attenuation in isotropic rocks.,” Geophysics, vol. 82, no. 2, pp. D133-D154, 2017.
D. Choi, Poudel, N., Cronin, S. B., and Shi, L., “Effects of basal-plane thermal conductivity and interface thermal conductance on the hot spot temperature in graphene electronic devices,” Applied Physics Letters, vol. 110, pp. 073104, 2017. Publisher's Version
X. Chen, Jarvis, K., Sullivan, S., Li, Y., Zhou, J., and Shi, L., “Effects of grain boundaries and defects on anisotropic magnon transport in textured Sr14Cu24O41,” Phys. Rev. B, vol. 95, pp. 144310, 2017. Publisher's Version
J. Botto, Fuchs, S. J., Fouke, B. W., Clarens, A. F., Freiburg, J. T., Berger, P. M., and Werth, C. J., “Effects of Mineral Surface Properties on Supercritical CO2 Wettability in a Siliciclastic Reservoir,” Energy & Fuels, vol. 31, no. 5, pp. 5275-5285, 2017. Publisher's VersionAbstract
Wettability is a key reservoir characteristic influencing geological carbon sequestration (GCS) processes, such as CO2 transport and storage capacity. Wettability is often determined on a limited number of reservoir samples by measuring the contact angle at the CO2/brine/mineral interface, but the ability to predict this value remains a challenge. In this work, minerals comprising a natural reservoir sample were identified, and the influence of their surface roughness and mineralogy on the contact angle was quantified to evaluate predictive models and controlling mechanisms. The natural sample was obtained from the Mount Simon formation, a representative siliciclastic reservoir that is the site of a United States Department of Energy CO2 injection project. A thin section of the Mount Simon sandstone was examined with compound light microscopy and environmental scanning electron microscopy (ESEM) coupled with energy-dispersive X-ray spectroscopy (EDS). Quartz and feldspar were identified as dominant minerals and were coated with various reddish black precipitates consistent with illite clay and iron oxide hematite. Contact angle (θ) measurements were conducted for the four representative minerals and the Mount Simon sample over a range of pressures (2–25 MPa) at 40 °C. At supercritical conditions, all samples are strongly water-wet, with contact angles between 27° and 45°. Several predictive models for contact angle were evaluated for the mineral and Mount Simon samples, including the Wenzel and Cassie–Baxter models, plus newly proposed modifications of these that account for the fraction of different minerals comprising the reservoir sample surface, the surface roughness, and the extent that roughness pits are filled with brine. Modeling results suggest that the fraction of mineral surfaces containing roughness pits filled with brine is the most important reservoir characteristic that controls wettability in the Mount Simon sandstone, followed by surface mineralogy. To our knowledge, this is one of the few studies to investigate the effects of individual minerals on the wettability of a natural reservoir sample.
S. Deng, Wang, Q., and Ren, P., “Estimating and modeling charge transfer from the SAPT induction energy,” Journal of Computational Chemistry, 2017.
E. D. Maalouf and Torres-Verdín, C., “Estimation of rock stiffness coefficients in VTI formations using LWD acoustic measurements (Expanded Abstract),” Society of Petrophysicists and Well Log Analysts (SPWLA) 58th Ann. Logging Symposium. Oklahoma City, OK, June 17-21, 2017.
J. Selvakumar and Bakolas, E., “Evasion with Terminal Constraints from a Group of Pursuers using a
Matrix Game Formulation
,” American Control Conference. Seattle, WA, 2017.PDF icon jseb_acc17.pdf

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