Continued advances in digital design software and 3D printing methods enable innovative approaches in the development of new educational tools for laboratory-based STEM (science, technology, engineering and mathematics) learning. The decreasing cost of 3D printing equipment and greater access provided by university fabrication centers afford unique opportunities for educators to transcend the limitations of conventional modes of student engagement with analytical instrumentation. This work shares successful efforts at Wabash College to integrate user-friendly and inexpensive 3D printed instruments kits into introductory STEM coursework. The laboratory kits and activities described provide new tools for engaging students in the exploration of instrument design and performance. These experiences provide effective ways to assist active-learners in discovering the technology and fundamental principles of analysis and deliberately confront the “black box” perception of instrumentation.

In this paper, the variation in device parameters is investigated with respect to temperature by considering the combination of HfO2-SiO2 on 4H-SiC n-IGBT. Two-dimensional numerical simulations using Setaurus TCAD have been performed to analyze the changes in static and dynamic characteristics. The switching waveforms have been analyzed using a clamped inductive circuit with and without HfO2. It seems that the presence of HfO2 in the dielectric stack has a considerable impact on the device turn off time.

The extreme heat resistance of dormant bacterial spores strongly depends on the extent of protoplast dehydration and the concentration of dipicolinic acid (DPA) and its associated calcium salts (Ca-DPA) in the spore core. Recent experiments have suggested that this heat resistance depends on the properties of confined water molecules in the hydrated Ca-DPA-rich protoplasm, but atomistic details have not been elucidated. In this study, we used reactive molecular dynamics (RMD) simulations to study the dynamics of water in hydrated DPA and Ca-DPA as a function of temperature. The RMD simulations indicate two distinct solid-liquid and liquid-gel transitions for the spore core. Simulation results reveal monotonically decreasing solid-gel-liquid transition temperatures with increasing hydration. Additional calculations on the specific heat and free energy of water molecules in the spore core further support the higher heat resistance of dehydrated spores. These results provide an insight into the experimental trend of moist-heat resistance of bacterial spores and reconciles previous conflicting experimental findings on the state of water in bacterial spores.

Diatoms microalgae represent a natural source of highly porous biosilica shells (frustules) with promising applications in a wide range of technological fields. Functionalization of diatoms’ frustules with tailored luminescent molecules can be envisaged as a convenient, scalable biotechnological route to new light emitting silica nanostructured materials. Here we report a straightforward protocol for the in vivo modification of Thalassiosira weissflogii diatoms’ frustules with a red emitting organic dye based on thienyl, benzothiadiazolyl and phenyl units. The metabolic insertion of the dye molecules into the diatoms shells, combined with an acidic-oxidative isolation protocol of the resulting dye stained biosilica, represents a novel strategy to develop highly porous luminescent biosilica nanostructures with promising applications in photonics.

The stability of VFB catholytes was investigated using both light-scattering measurements and visual observation. V2O5 precipitates after an induction time τ which shows an Arrhenius variation with temperature. The value of τ increases with increasing [S] and with decreasing [VV] but the activation energy remains constant with a value of (1.791±0.020) eV. Plots of ln τ against [S] and [VV] show good linearity and the slopes give values of βS = 2.073 M-1 and βV5 = –3.434 M-1 for the fractional rates of variation of τ with [S] and [VV], respectively. Combining the Arrhenius Equation with the observed log-linear variation of τ with [S] and [VV] provides a model for simulating the stability of catholytes. The addition of H3PO4 has a strong stabilizing effect on catholytes at higher temperatures. For example, at 50°C the induction time for precipitation for a typical catholyte is enhanced ∼ 12.5-fold by 0.1 M added H3PO4. At concentrations of H3PO4 less than ∼0.04 M, the precipitation time increases with increasing concentration at all temperatures investigated (30–70°C). At higher concentrations, induction time begins to decrease with increasing concentration of H3PO4: the changeover concentration depends on the temperature. Experiments at 70°C using other phosphate additives (sodium triphosphate, Na5P3O10, and sodium hexametaphosphate, (NaPO3)6) showed similar results to H3PO4.

Spherical aluminum oxide (γ-phase) nanoparticles with sizes below 30 nm were synthesized by pulsed laser ablation in liquids. The wavelength and energy fluence of the nanosecond laser were set at 1064 nm and ∼1x103 J/cm2, respectively. The optimal repetition rate to maximize the production of those nanoparticles was determined to be at 2,129±64 Hz. Therefore, the lifetime of the cavitation bubble was estimated to be around 0.47±0.01 ms.

Transparent optical ZnO–Bi2O3–B2O3 (ZBB) glass-ceramics were created by the melt quenching technique. In this work, a melt of the glass containing stoichiometric ratios of Zn/Bi/B and As was studied. Differential scanning calorimeter (DSC) measurements was used to measure the thermal behavior. VIS/NIR transmission measurements were used to determine the transmission window. X-ray diffraction (XRD) was used to determine crystal phase. In this study, we explore new techniques and report a detailed study of in-situ XRD of the ZBB composition in order to correlate nucleation temperature, heat treatment temperature, and heat treatment duration with induced crystal phase.

We synthesized twin-mesogen epoxy polymer in which there were two 2,7-naphthalene benzoate as mesogens connected by four carbons alkyl chain and investigated the effects of higher-order structure changes due to the differences of alkyl chain length and mesogen groups on thermal conductivities. This polymer is abbreviated as TME2,7-NB4. NB means naphthalene benzoate and 4 means spacing carbon number. As a result, the thermal conductivity of TME2,7-NB4 was higher than that of TME2,7-NB8, but the coherent length D was less than that of TME2,7-NB8.

Tissue engineering and regenerative medicine are increasingly taking advantage of active materials, allowing to provide specific clues to the cells. In particular, the use of electroactive polymers that deliver an electrical signal to the cells upon mechanical solicitation, open new scientific and technological opportunities, as they in fact mimic signals and effects that occur in living tissues, allowing the development of suitable microenvironments for tissue regeneration. Thus, a novel overall strategy for bone and muscle tissue engineering was developed based on the fact that these cells type are subjected to mechano-electrical stimuli in their in vivo microenvironment and that piezo- and magnetoelectric polymers, used as scaffolds, are suitable for delivering those cues. The processing and functional characterizations of piezoelectric and magnetoelectric polymers based on poly(vinylindene fluoride) and poly-L-lactic acid in a variety of shapes, from microspheres to electrospun mats and three dimensional scaffolds, are shown as well as their performance in the development of novel bone and muscle tissue engineering.

Here, we report an experimental characterization of a new subcritical graphene nanostructure termed a crinkle ruga. Multilayer graphene forms crinkles as a periodic mode of buckling if the ratio of periodic buckling span to thickness is smaller than a critical value. Otherwise, it forms wrinkles. The crinkles have sawtooth-shaped profiles with their faces perfectly flat and the tips of the peaks and valleys highly curved. Our AFM measurements show that the width of the curvature focusing band at the tip is very narrow, e.g. smaller than 16 nm for a 6o crinkle, indicating a strong influence of flexoelectric coupling in crinkle formation. We also found that concavity or convexity of crinkle tips, i.e. parity of the crinkle, can be controlled. Due to the flexoelectric coupling, the concave tip at the crinkle valley is positively charged, and the convex tip at the crinkle peak negatively charged. In addition, here, we demonstrate that the charges at the crinkle tips can attract macromolecules in adsorption experiments. We show linearly-aligned adsorption of C60 along crinkle valleys on an HOPG surface. In another experiment, we exhibit period-doubled adsorption of lambda DNA on an HOPG surface, possibly caused by ion kinetics involved in the DNA adsorption along the crinkle valleys.

Current practice for commercial spent nuclear fuel management in the United States of America (US) includes storage of spent fuel in both pools and dry storage cask systems at nuclear power plants. Most storage pools are filled to their operational capacity, and management of the approximately 2,200 metric tons of spent fuel newly discharged each year requires transferring older and cooler fuel from pools into dry storage. In the absence of a repository that can accept spent fuel for permanent disposal, projections indicate that the US will have approximately 134,000 metric tons of spent fuel in dry storage by mid-century when the last plants in the current reactor fleet are decommissioned. Current designs for storage systems rely on large dual-purpose (storage and transportation) canisters that are not optimized for disposal. Various options exist in the US for improving integration of management practices across the entire back end of the nuclear fuel cycle.

A model of a High Voltage CMOS (HV-CMOS) Monolithic Active Pixel Sensor (MAPS) has been modelled using Technology Computer Aided Design (TCAD). The model has incorporated both the active region and the on-pixel readout circuits which were comprised of a source follower amplifier and an integrated charge amplifier. The simulation has examined the electrical characteristics and response output of a HV-CMOS MAPS sensor using typical dimensions, levels of doping in the structural layers and bias conditions for this sensor. The performance of two alternate designs of amplifier have been examined as a function of the operating parameters. The response of the sensor to the incidence of Minimum Ionizing Particles (MIPs) at different energies has been included in the model.

A brief review of the status of our understanding of the occupation of the Pu 5f states is provided herein, with an emphasis upon experimental measurements.

We have developed high affinity Molecularly Imprinted Polymers (MIPs) for neurotransmitters such as dopamine, noradrenaline and caffeine. These polymer particles are mixed within the bulk of screen-printed ink allowing masss-producible bulk modified MIP Screen-Printed Electrodes (MIP-SPEs) to be realised. We have explored different SPE supporting surfaces, such as polyester, tracing paper and household-printing paper. The performance of those MIP-SPEs is studied using the Heat-Transfer Method (HTM), a patented thermal method. With the combination of screen-printing techniques and thermal detection, it is possible to develop a portable sensor platform that is capable of low-cost and straightforward detection of biomolecules on-site. In the future, this unique sensor architecture holds great promise for the use in biomedical devices.

Boron nitride (BN) has a very high thermal conductivity and excellent thermal shock resistance. These properties make BN an important material for industrial applications involving surfaces in contact with molten metals. These applications require straightforward deposition methods that produce uniform BN coatings. Using borazine (B3N3H6) as a precursor, we deposited BN coatings on silicon substrates by cold-wall chemical vapor deposition (CVD). The microstructure, composition, and morphology of the coatings were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and electron energy loss spectroscopy (EELS). These characterizations show that the BN coatings deposited are uniform, predominantly of hexagonal structure, and N-rich.

Development of an iodine immobilization technique that can fix radioactive iodine in waste form for a long period and constrain its leaching into pore water is necessary in order to secure the long-term safety of geological disposal of transuranic (TRU) waste.

Lead borate glass vitrified at a low temperature is regarded as one of the promising immobilization materials of Iodine-129 which will be removed from spent AgI filters generated from reprocessing plants and may have a significant effect on long term safety of geological disposal.

Leaching experiments in bentonite-equilibrium water have been conducted to understand the lead borate glass dissolution behaviors in possible geological disposal conditions. Boron dissolved with the highest rate in all types of the solutions and was regarded as an index element to represent the glass dissolution rate. On the other hand, lead dissolved with a far slower rate. The chemical species and possible precipitating minerals of lead were examined by a geochemical calculation code for typical underground water. Altered glass surfaces were investigated by SEM, TEM and XRD. XRD analysis showed that the main constituent phase of the altered layer was hydrocerussite, Pb3(CO3)2(OH)2, that was predicted by the geochemical simulation as well.

A cadmium chloride activation treatment is essential for the production of high efficiency cadmium telluride (CdTe) solar cells. However, the effects of the treatment on the distributions of chlorine and sulphur within the device are not fully understood. Here, the detailed locations of chlorine and sulphur in a treated CdTe cell are determined in three dimensions by high resolution dynamic SIMS measurements. Chlorine is found to be present in grain boundaries, grain interiors, extended defects within the grain interiors, at the front interface, and in the cadmium sulphide layer. In each of these regions, the chlorine is likely to have significant effects on local electronic properties of the material, and hence overall device performance. Sulphur is found to have a U-shaped diffusion profile within CdTe grains, indicating a mixed grain boundary and lattice diffusion regime.

Nanoenergetic composites are of overwhelming interest to the Department of Defense because of the higher power output and the ability to finely tune the ignition thresholds of these composites. Recently, several variants of a nanoaluminum-poly(perfluorinated methacrylate) (AlFA) have been synthesized and optimized for a variety of applications including reactive warhead liners and bullet spotters. While conventional techniques such as thermal analysis and bomb calorimetry can be used to characterize the reaction mechanism and energy output of AlFA composites, characterizing their dynamic behaviour is more challenging. Bullet spotter applications require a material to be impact sensitive at very low velocities, yet be adequately insensitive. Several live-fire tests were conducted which revealed the AlFA50 material reacted consistently upon target impact at high velocities, but unreliably at very low velocities. In an effort to better understand the fundamental impact ignition mechanism and to determine the impact velocity threshold of AlFA50 a series of Taylor gas gun experiments were conducted. It was determined that the light-initiation mechanism was consistent with a pinch mechanism, and that the ignition velocity threshold was near 74 m/s. Based on these results, it was hypothesized that the addition of a filler material could be used to sensitize the AlFA50, and that Asay shear impact testing could be used to determine a more optimal shape of such inclusions. Experiments performed using the Asay shear impact test setup confirmed the pinch ignition mechanism, but observations also revealed that the size of the pinch point was important. Finally, it was shown that the addition of large glass beads (> 1mm in diameter) was effective at sensitizing the AlFA50 material at high and low velocities, with ignition observed at impact velocities as low as 35 m/s.

In this experiment, a new bimetal low–cost Cu–Sn alloy was synthesized and it was tested as catalyst for oxygen reduction reaction (ORR) in MFC and the results were compared with the commercially available Pt-C catalyst. Cyclic voltammetry for evaluating ORR of the test cathode containing Cu-Sn catalysts under oxygen saturated environment displayed large ORR current peak, showing less overpotential demand for ORR. Maximum power density of 457 mW/m2 obtained from MFC using Cu–Sn catalyst, was found to be slightly higher than the power density of 446 mW/m2 demonstrated by MFC using Pt based cathode. Biochemical conversion of organic matter to direct electric current in Cu–Sn based MFC occurred at a coulombic efficiency of 55.8%, while demonstrating 92% of chemical oxygen demand removal. This study demonstrated application of low cost Cu–Sn bimetal alloy as excellent ORR catalyst in MFC and would be very helpful to commission larger MFCs for field applications to harvest energy in the form of direct electricity from wastewaters while offering wastewater treatment.

Methods of obtaining large grain size and high crystallinity in absorber materials play an important role in fabrication of high-performance methylammonium lead iodide (MAPbI3) perovskite solar cells. Here we study the effect of adding small concentrations of Cd2+, Zn2+, and Fe2+salts to the perovskite precursor solution used in the single-step solution fabrication process. Enhanced grain size and crystallinity in MAPbI3 films were obtained by using 0.1% of Cd2+ or Zn2+in the precursor solution. Consequently, solar cells constructed with Cd- and Zn-doped perovskite films show a significant improvement in device performance. These results suggest that the process may be an effective and facile method to fabricate high-efficiency perovskite photovoltaic devices.