This paper presents the impact of three undergraduate research projects focusing on constructability assessment of adhesive-based wood-concrete composite structural members, on a solar heating technology that can be utilized in conjunction with this system and how these projects relate to engineering education and program development at Metropolitan State University of Denver (MSU Denver). The sustainable structures topic was pursued within senior project classes offered in summer 2013 and 2014 at MSU Denver. The first project addressed new members, while the second dealt with retrofits. These projects were motivated by faculty research in developing new sustainable construction systems using composites. Since underlining faculty research is on an international scale, students had direct access to researchers world-wide. Such research was used as an instrument in the “Experimental Methods in Structural Engineering” course. The students were also exposed to a broader-range of diverse ideas within the field of research by attending an international conference on timber bridges. The solar furnace project was run in parallel, providing students an opportunity to conduct research targeted at design and performance optimization of the heating units with the intention to assess the benefits of incorporating these devices into future buildings using the sustainable structural system technology. Experiences gained through the undergraduate research activities were applied in the design of a proposed Sustainable Systems Engineering degree program.

Since July 2014, thirteen European metrology organizations are collaborating to address some of the main metrological challenges faced by the developments of high-efficiency III-V multi-junction solar cells (MJSC). III-V MJSC structures are made of a high number of layers, which makes a pure experimental optimization difficult and expensive; this also limits the uncertainty of cell calibration due to the complexity of their spectral response. The project is structured in three distinct parts:

1. 1) improved accuracy in materials and transport characterization for existing MJSC;

2. 2) improved accuracy and repeatability in traceable efficiency characterization for MJSC cells with three or more junctions and finally,

3. 3) metrology for advance concept such as coupling with thermoelectric, dilute nitride, quantum dots or growth on Silicon.

We developed a new GaN on SiC growth method by metalorganic vapour phase epitaxy (MOVPE) using of a single 2-dimension-growth step. Prior to epitaxy, to inhibit pre-reaction of Si-face SiC substrate with TMGa and NH3, TMAl was flowed without NH3. 1.5 μm of undoped crack-free GaN was grown on 6H-SiC (Si-face). Without buffer layer, the vertical resistance of GaN/SiC structure was found to be around 82.1Ω as determined by I-V characteristic. Further reduction in vertical resistance is expected by growth of n-GaN (1.5μm)/SiC structure (300μm). We also expect a SiC-based GaN heterostructure vertical FET will achieve high power and high switching speed performance.

Uranium dioxide, as the standard nuclear fuel in pressurized water reactors, motivates intensive research to get further insight into the link between radiation damage and microstructure evolution of the material. Cerium dioxide is often considered as a non-radioactive model material for uranium dioxide, for which the experimental study of radiation damage could be performed more easily. Using first-principles calculations based on the density functional theory (DFT) and its DFT+U variant, we compare these two oxides in terms of point defect formation.

Because of the high energy density, easy ignition, and good storability, mechanically alloyed Al·Mg powder has the potential to improve the performance characteristics of various energetic and gas-generating materials. Here, the use of this powder in combustible mixtures for generation of oxygen and hydrogen is explored. The mixtures for oxygen generation consisted of sodium chlorate, nanoscale cobalt oxide catalyst, and Al·Mg powder, while those for hydrogen generation included water, polyacrylamide as a gellant, and Al·Mg powder. To increase hydrogen yield, ammonia borane (NH3BH3) was also added to Al·Mg − water mixtures. Combustion experiments were conducted in an argon environment, using laser ignition. The thermal wave propagation over the oxygen-generating mixtures was studied using infrared video recording. It has been shown that mechanically alloyed Al·Mg material is a promising alternative to currently used iron because significantly smaller amounts of this additive are needed for a steady propagation of the combustion wave. The hydrogen generation experiments have shown that mixtures of mechanically alloyed Al·Mg powder with 10−60 wt% gelled water are combustible, with the front velocities exceeding the values obtained for the mixtures of water with nanoscale Al. Hydrogen yield was measured using mass-spectrometry. In the mixtures that included ammonia borane, D2O was used instead of H2O. Measurements of H2, D2, and HD concentrations in the product gas provided insight into the reaction mechanisms. The isotopic tests have shown that AB participates in two parallel processes − thermolysis and hydrolysis, thus increasing hydrogen yield.

The present paper shows the applicability of the Dual Boundary Element Method to analyze plastic, visco-plastic and creep behavior in fracture mechanics problems. Several models with a crack, including a square plate, a holed plate and a notched plate are analyzed. Special attention is taken when the discretization of the domain is done. In Fact, for the plasticity and viscoplasticity cases only the region susceptible to yielding was discretized, whereas, the creep case required the discretization of the whole domain. The proposed formulation is presented as an alternative technique to study this kind of non-linear problems. Results from the present formulation are compared to those of the well-established Finite Element Technique, and they are in good agreement. Important fracture mechanic parameters such as KI, KII, J- and C- integrals are also included. In general, the results, for the plastic, visco-plastic and creep cases, show that the highest stress concentrations are in the vicinity of the crack tip and they decrease as the distance from the crack tip is increased.

The protein survivin (Sur) has been considered as a potential cancer biomarker due to its involvement in disrupting normal cell cycle by stimulating proliferation and inhibiting cell apoptosis. In this work, we have focused on exploring novel platforms for sensitive monitoring of Sur expression, based on molecular beacons and protein modulation of plasmon-controlled fluorescence. In this framework, we show that Sur can be employed in gating the resonance energy transfer (gRET) between fluorescein isothiocyanate probe dye (FITC) and plasmonic citrate-capped gold nanoparticles (AuNP@Cit). Furthermore, we have designed fluorescent dye-bearing molecular beacons (MBs) targeting nucleotides of the survivin mRNA. The antisense oligonucleotide complementary to the target sequence, inserted in the loop area of the hairpin MB structure, has enabled the fluorescence turn-ON MB switching in the presence of the target, thus signaling the high Sur mRNA levels and enhanced Sur protein expression.

The heat transfer coefficients of homogeneous and hybrid micro-porous copper foams, produced by the Lost Carbonate Sintering (LCS) process, were measured under one-dimensional forced convection conditions using water coolant. In general, increasing the water flow rate led to an increase in the heat transfer coefficients. For homogeneous samples, the optimum heat transfer performance was observed for samples with 60% porosity. Different trends in the heat transfer coefficients were found in samples with hybrid structures. Firstly, for horizontal bilayer structures, placing the high porosity layer by the heater gave a higher heat transfer coefficient than the other way round. Secondly, for integrated vertical bilayer structures, having the high porosity layer by the water inlet gave a better heat transfer performance. Lastly, for segmented vertical bilayer samples, having the low porosity layer by the water inlet offered the greatest heat transfer coefficient overall, which is five times higher than its homogeneous counterpart.

A series of fluorine appended highly conjugated fullerenes were prepared containing fluoro-α-cyanostilbene and aryl ester units. These modified PCBM dyads are fully characterized by NMR, Mass spectrometry, UV-vis, and cyclic voltammetry (Figures 1-4). It was found that the presence of fluoro-α-cyanostilbenes and esters affects the cyclic voltammetry and absorption in the UV-Vis region. The PCBA modified fullerenes significantly influences the HOMO-LUMO energy and wide absorption compared to PCBM.

Magnesium silicide (Mg2Si) has attracted much interest as an n-type thermoelectric material because it is eco-friendly, non-toxic, light, and relatively abundant compared with other thermoelectric materials. In this study, we tried to improve the thermoelectric performance by doping Sb and Ge in the Mg2Si, as well as further optimizing x in the carrier concentration to cause phonon scattering. A high purity Mg2Si was synthesized from metal Mg and Sb doped Si-Ge alloy by using spark plasma sintering (SPS) equipment. The sintered samples were cut and polished. They were evaluated by using X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses. The carrier concentration of the samples was measured by using Hall measurement equipment. The electrical conductivity and Seebeck coefficient were measured by using a standard four-probe method in a He atmosphere. The thermal conductivity was measured by using a laser-flash system. We succeeded in obtaining a Sb doped Mg2Si0.95Ge0.05 sintered body easily without any impurities with the SPS equipment. The electrical conductivity of the sample was increased, and thermal conductivity was decreased by increasing the amount of doped Sb. The dimensionless figure of merit ZT became 0.74 at 733 K in the Mg2Si0.95-x Ge0.05Sbx sample with x = 0.0022.

The scalable storage of renewable energy by means of converting water to hydrogen fuels electrochemically hinges on fundamental improvements in catalytic materials. However, many applications exist where an extended lifetime is virtually crucial for their functionality and success, e.g. in case of limited accessibility such as tire pressure sensors or biomedical implants. For these kinds of applications, the ultimate power supply should be a self-renewing energy source. This strategy is pursued by the concept of Micro Energy Harvesting (MEH). Within a MEH system a micro generator converts ambient energy to electrical energy for driving an application. Unfortunately, it is not ensured that the ambient energy level will maintain always high enough to provide sufficient power to the system as harvested energy usually manifests itself in rather irregular, random and low-energy bursts. One appealing form of integrated energy storage is the use of H2/air, a so called fuel cell type (FC) battery. Such devices promise very high volumetric energy densities of more than 2000 Wh/l. Consequently, this type of battery has recently attracted more and more attention and primary as well as secondary cells have been realized. Alkaline polymer electrolyte fuel cells have been recognized as the most promising solution in order to overcome the dependency on noble metal catalysts. Nevertheless, further improvements for these kinds of fuel cells have to be reached with respect to high power. Therefore, one promising approach is to increase the skin surface of porous chromium decorated nickel electrodes for enhancement of exchange current density by forming three-dimensional (3D) microstructures directly into the electrode. Therefore, a novel laser structuring process was applied using ultrashort laser pulses. Ultrashort laser processing of complex multimaterial systems for energy storage allow for precise material removal without changing the material properties. By applying this novel laser-based structuring technique, 3D microstructures could be formed permitting shortened diffusion lengths between the electrolyte and the electrode surface being necessary for increased exchange current densities.

The electrical and mechanical characteristics of ionic-covalent entanglement hydrogels consisting of combinations of the edible biopolymers gellan gum and gelatin were investigated. Impedance analysis and compression testing showed that these hydrogels (with water content = 97%) exhibited conductivity values of up to 13 mS/cm and compressive stress at failure values of up to 1.0 MPa. These are suitable characteristics for printed and mechanically robust wet device components.

A cylindrical-shaped micropillar array embedded microfluidic device was proposed to enhance the dispersion of cell clusters and the efficiency of single cell encapsulation in hydrogel. Different sizes of micropillar arrays act as a sieve to break Escherichia coli (E. coli) aggregates into single cells in polyethylene glycol diacrylate (PEGDA) solution. We applied the external force for the continuous breakup of cell clusters, resulting in the production of more than 70% of single cells into individual hydrogel particles. This proposed strategy and device will be a useful platform to utilize genetically modified microorganisms in practical applications.

Optical properties and thermal relaxation dynamics of resonantly excited plasmons are important in applications for optoelectronics, biomedicine, energy, and catalysis. Geometric optics of polydimethylsiloxane (PDMS) thin films containing uniformly or asymmetrically distributed polydisperse reduced AuNPs or uniformly distributed monodisperse solution-synthesized AuNPs were recently evaluated using a compact linear algebraic sum. Algebraic calculation of geometric transmission, reflection, and attenuation for AuNP-PDMS films provides a simple, workable alternative to effective medium approximations, computationally expensive methods, and fitting of experimental data. This approach allows for the summative optical responses of a sequence of 2D elements comprising a 3D assembly to be analyzed. Thin PDMS films containing 3-7 micron layers of reduced AuNPs were fabricated with a novel diffusive-reduction synthesis technique. Rapid diffusive reduction of AuNPs into asymmetric PDMS thin films provided superior photothermal response relative to thicker films with AuNPs reduced throughout, with a photon-to-heat conversion of up to 3000°C/watt which represents 3-230-fold increase over previous AuNP-functionalized systems. Later work showed that introduction of AuNPs into PDMS enhanced thermoplasmonic dissipation coincident with internal reflection of incident resonant irradiation. Measured thermal emission and dynamics of AuNP-PDMS thin films exceeded emission and dynamics attributable by finite element analysis to Mie absorption, Fourier heat conduction, Rayleigh convection, and Stefan-Boltzmann radiation. Refractive-index matching experiments and measured temperature profiles indicated AuNP-containing thin films internally reflected light and dissipated power transverse to the film surface. Enhanced thermoplasmonic dissipation from metal-polymer nanocomposite thin films could affect opto- and bio-electronic implementation of these systems.

Harvesting solar energy, is only one of the incentives of incorporating photosynthetic proteins in electrochemical devices. Understanding the interface of photosynthetic protein complexes and organic\inorganic underlying electrodes can give rise to development of new generation of nano-bioelectronics for other applications such as sensing, as well. Previous approaches in fabricating photosynthetic bio-hybrid electrochemical solar cells were mainly based on metallic electrodes with protein complexes attached, either directly or through linker molecules. Due to the energy band structure in semiconductors, they potentially can be useful for selective charge transfer in an electrochemical device. In the current study, a two terminal sealed bio-hybrid solar cell device was fabricated comprising of hydrothermally grown ZnO nanowires on fluorine doped tin oxide (FTO) glass working electrode, a Pt counter electrode, and methyl viologen (MV) as a single diffusible redox mediator. The ZnO working electrode was initially characterized using scanning electron microscopy (XRD) and X-ray diffraction (XRD). A solution of dimeric Rhodobacter sphaeroides – light harvesting 1 (RC-LH1) core complexes and redox electrolyte was injected into the cavity between working and counter electrodes. Such structure resulted in ∼0.64 µA.cm-2 photocurrent density and ∼0.24 V open circuit potential difference in the dark and under illumination. Additionally, the device stability tests demonstrated that the current response of such devices remained unchanged after 33 hours storage in the dark.

Public health and environmental protection concerns provoked by phenolic compounds pollution impose the development of sensitive, rapid and cost effective methods for in situ phenols monitoring. Given that biosensors based techniques could face these challenges, a variety of such devices was suggested and applied for phenolic compounds quantification. Their majority are based on the polyphenol oxidase (PPO) catalyzed phenols oxidation to catechol and then, to quinones, coupled with the registration of the quinones reduction current. Nevertheless, quinoid products polymerization involving electrode passivation corrupts the biosensors operational stability. Thus, to avoid this drawback, in this work is proposed another approach for phenolic compounds quantification based on the electrochemical detection of the oxygen depletion during PPO catalyzed catechol oxidation using a Clark type electrode with a disposable active enzyme membrane. The oxygen probe was modified in comparison to the commercial ones: its flat front allowed ensuring a good contact with the active enzyme membrane and the gold multicathode uniformly dislocated on the surface of the flat front permitted eliminating O2 diffusional constraints. The active enzyme membrane was prepared by drop-coating of a mixture of PPO and gelatin onto a gelatin-saturated cellulose filter. A linear calibration graph for catechol determination was obtained in the range up to 0.7 mM with a slope of 0.902 μA/mM, at pH 6.5 and ambient temperature. The steady-state response to catechol of the biosensor was reached in 120 s. The biosensor had an excellent reproducibility (RSD<3%) due to the reliable enzyme immobilization technique, allowing the preparation of active enzyme membranes with identical characteristics. The proposed biosensor provided stable response and free of interferences measurements since the unique possible electrochemical reaction is O2 reduction. Another biosensor advantage is associated with the use of disposable prefabricated active enzyme membranes.

A photoexcitation energy transfer process in blends of PbS QDs of different size is considered. An analysis of photoluminescence kinetics shows drastic increase of acceptor decay times. In a triple blend a merger of photoluminescence decay curves recorded at different spectral regions is found. Different pathways of the energy transfer, including the transfer from the in-gap state, are considered.

Resonant optical rod antennas are made from aluminum using electron-beam lithography and are optically characterized by linear dark-field microscopy and nonlinear multi-photon luminescence spectroscopy. It is demonstrated that by exciting close to the interband transition of aluminum at about 1.5 eV different radiative decay channels can be addressed. Over a period of weeks, a slight spectral red-shift and a decrease in the scattering intensity are observed due to the formation of a native oxide layer at the metal-air interface. To investigate the concurrent influence of shape transformation and dielectric environment on the spectral response function we carry out numerical calculations using finite difference time domain (FDTD) methods. It is found that the induced energy shift is mainly determined by the change of the dielectric constant in the nanovicinity resulting in an overall red-shift as seen in the experiment. These findings allow for a better understanding of designing and modeling plasmonic aluminum nanostructures for e.g. UV sensing where the shift in peak resonance and linewidth are key observables.