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.
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.
I. Shovkun and Espinoza, N. D., “Coupled fluid flow-geomechanics simulation in stress-sensitive coal and shale reservoirs: Impact of desorption-induced stresses, shear failure, and fines migration,” Fuel, vol. 195, pp. 260–272, 2017.
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.
N. Khusnatdinov, Resnick, D. J., Singhal, S., Grigas, M. M., and Sreenivasan, S. V., “Development Of An Inkjet-enabled Adaptive Planarization Process,” SPIE Photomask Technology Conference, vol. 10451. SPIE, Monterey CA, 2017. Publisher's VersionAbstract
Nanoimprint lithography manufacturing utilizes a patterning technology that involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. The technology faithfully reproduces patterns with a higher resolution and greater uniformity compared to those produced by photolithography equipment. Throughputs of 80 wph have been demonstrated, and mix and match overlay of 3.7nm 3 sigma has been achieved. The technology has already been successfully applied as a demonstration to the fabrication of advanced NAND Flash memory devices. A similar approach can also be applied however to remove topography on an existing wafer, thereby creating a planar surface on which to pattern. In this paper, a novel adaptive planarization process is presented that addresses the problems associated with planarization of varying pattern densities, even in the presence of pre-existing substrate topography. The process is called Inkjet-enabled Adaptive Planarization (IAP). The IAP process uses an inverse optimization scheme, built around a validated fluid mechanics-based forward model that takes the pre-existing substrate topography and pattern layout as inputs. It then generates an inkjet drop pattern with a material distribution that is correlated with the desired planarization film profile. This allows a contiguous film to be formed with the desired thickness variation to cater to the topography and any parasitic signatures caused by the pattern layout. In this work, it was demonstrated that planarization efficiencies of up to 99.5% could be achieved, thereby reducing an initial similar to 100nm wafer topography down to as little as 0.6nm.
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.
Z. Sun, Espinoza, N. D., Balhoff, M. T., and Dewers, T. A., “Discrete element modeling of micro-scratch tests: investigation of mechanisms of CO2 alteration in reservoir rocks,” Rock Mechanics and Rock Engineering, vol. 50, pp. 3337–3348, 2017.
Z. Sun, Balhoff, M. T., Espinoza, N. D., and others,Discrete element modeling of micro-scratch tests on rocks altered by CO 2,” in 51st US Rock Mechanics/Geomechanics Symposium, 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, AIAA Paper 2017-3361. 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 order to invoke aeroelastic coupling between the nozzle wall and the internal flow. Single point measurements 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.
E. J. Guiltinan, Cardenas, B. M., Bennett, P. C., Zhang, T., and Espinoza, N. D., “The effect of organic matter and thermal maturity on the wettability of supercritical CO2 on organic shales,” International Journal of Greenhouse Gas Control, vol. 65, pp. 15–22, 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.
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

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