Chemical Synthesis and Processing

• Drying ovens, sintering oven
• Balances
• General and air-sensitive synthetic glassware
• Lab Digital Overhead Stirrer
• Schlenk lines mounted within fume hoods
• Buchi Rotovapor R3
• Sorvall ST16 centrifuge with TX400 rotor, inserts for 15 mL and 50 mL conical tubes
• Branson Digital (tip horn) Sonifier with ½ Inch Tip and sound enclosure box, jacketed beakers for thermal stability during prolonged sonication

Electrical and Monitoring Systems

• DC Regulated Power Supply, 0-50V, <3A, CircuitSpecialists.com, Model CSI5003XE
• Rigol DS1054Z oscilloscope
• Stepper motors and stepper motor controllers, micro controller boards, linear translation stages
• CH Instruments model CHI600E electrochemical analyzer
• Thermocouple digital temperature logger

Spectroscopic and Optical Systems

• Lecia DM750 upright light microscope with Lecia ICC50 HD camera and 4x, 10x, 40x, and 100x (oil) objectives
• StellarNet fiberoptic spectrometer system with SL1 light source, BlackComet UV-Vis detector, Dwarf-Start-NIR-25 near-infrared detector, cuvette holder, dip probe
• Opto Engine LLC diode pumped solid state lasers, 1-50 mW, 561 nm and 655 nm
• Various optical components: mirrors, lenses, filters, mounts, power meters, monochromators

Other

• Gaussian 16 and GaussView 16 computational chemistry software running on Linux desktop computer with 16 cores, 64 GB ram, nVidia Tesla K40 and nVidia Quadro K2200 graphics cards
• VAC Omni-Lab argon glovebox with refrigerator (note: no oxygen or humidity sensors)
• Flammable material storage refrigerator
• ThorLabs HPLS-30-04 High power solid state white light lamp
• Six workstations equipped with computers, printer/scanner
   

Single walled carbon nanotubes (SWNTs) exhibit material characteristics beyond their tubular diameters and lengths.  Specifically, SWNT present either metallic or semiconducting (of various band gaps) characteristics in otherwise similar structures due to the chiral wrapping vector of the tube.  Because successful implementation of these materials within both electronic and sensing schemes can be hindered by the type or chiral purity of the SWNT, methods to efficiently purify preparative quantities of SWNT (which are synthesized with inherent inhomogeneity in structure) are needed to afford but fundamental investigations into SWNT properties and integration of these materials within next generation devices.   

The purification of SWNT using hydrogel microspheres was first demonstrated by type purification (semiconducting vs. metallic) and later by chirality (semiconducting of different bandgap) and handedness.  Additionally, other studies have focused on the thermodynamic, kinetic, and chemical aspects of the SWNT/gel interaction that affords purification.  The Tvrdy Lab in interested in further understanding and exploiting the nature of surfactant-mediated chirality-dependent interactions between SWNT and hydrogel microspheres.  

Relevant Tvrdy Lab Publications:

Watts, B.P.; Barbee, C.H.; and Tvrdy, K.; “Exploiting the Physiochemical Interactions between Single-Walled Carbon Nanotubes and Hydrogel Microspheres to Afford Chirally Pure Nanotubes” ACS Appl. Nano Mater. (2019) 2: 3615-3625

Semiconducting quantum dots (QDs) are spherical nanoscale crystals also referred to as “artificial atoms” that exhibit discretized and tunable absorbance and emission features—like atomic spectra—despite their composition of ≈50-5,000 atoms.  Unfortunately, due to the high computational cost associated with modeling to-scale QD systems, dynamic processes fundamental to both QD creation and behavior such as: QD growth, surface atom rearrangement, defect formation, etc., cannot be addressed on an atomistic level using standard computational methods.  New approaches are necessary to simulate QD behavior while also preserving molecular scale properties such as electron density, structure energy, and density of states.

The general approach of charge equilibration was first developed for molecular dynamics simulations of organic or biomolecules.  This method involves the simultaneous per-atom treatment of atomic ionization and interatomic coulombic interactions to globally minimize the energy of a static structure.  One significant advantage of charge equilibration is its low computational cost when treating relatively large systems comprised of many-electron atoms, such as QDs.  The Tvrdy Lab is interested in the modification and expansion of charge equilibration methods to develop inexpensive-yet-accurate methods of simulating both static and dynamic processes related to QD growth and behavior.  

Relevant Tvrdy Lab Publications:

Weeks, N.; and Tvrdy, K.; “Atomistic Modeling of Quantum Dots at Experimentally Relevant Scales Using Charge Equilibration” J. Phys. Chem. A (2017) 121: 9346-9357

Nearly 40 million MRI scans are performed annually in the United States to screen injury and disease by spatially-mapping human tissue.  While a valuable diagnostic tool, this method could be enhanced by the addition of temperature data—creating a spatial-temperature map of tissue—as a variety of ailments including growing tumors have shown to cause locally heightened temperatures in the body.  Because of backward compatibility within existing clinical MRI infrastructure, the development of spatially and thermally responsive contrast agents have the potential to diversify and improve an already impactful diagnostic tool at relatively low cost.

The Tvrdy Lab and the lab of Zbigniew Celinski (UCCS Dept. of Physics and Energy Science) are interested in the synthesis, characterization, and implementation of doped magnetite MNPs that both readily diffuse through biological tissue and exhibit temperature dependent magnetic response near body temperature.  

Relevant Tvrdy Lab Publications:

Hankiewicz, J.C.; Stoll, J.A.; Stroud, J.; Davidson, J.; Livesey, K.L.; Tvrdy, K; Roshko, A.; Russek, S.E.; Stupic, K.; Bilski, P.; Camoley, R.E.; and Celinski, Z.J.; “Nano-sized Ferrite Particles for Magnetic Resonance Imaging Thermometry” J. Magn. Magn. Mater. (2019) 469: 550-557