Areas Of National Need Research Articles

Towards quantifying microbial dispersal in the environment.

Towards quantifying microbial dispersal in the environment.

Irradiation-Driven Restructuring of UO2 Thin Films: Amorphization and Crystallization

Combustion synthesis in uranyl nitrate-acetylacetone-2-methoxyethanol solutions was used to deposit thin UO2 films on aluminum substrates to investigate the irradiation-induced restructuring processes. Thermal analysis revealed that the combustion reactions in these solutions are initiated at ∼160 °C. The heat released during the process and the subsequent brief annealing at 400 °C allow the deposition of polycrystalline films with 5-10 nm UO2 grains. The use of multiple deposition cycles enables tuning of the film thicknesses in the 35-260 nm range. Irradiation with Ar2+ ions (1.7 MeV energy and a fluence of up to 1 × 1017 ions/cm2) is utilized to generate a uniform distribution of atomic displacements within the films. X-ray fluorescence (XRF) and alpha-particle emission spectroscopy showed that the films were stable under irradiation and did not undergo sputtering degradation. X-ray photoelectron spectroscopy (XPS) showed that the stoichiometry and uranium ionic concentrations remain stable during irradiation. The high-resolution electron microscopy imaging and electron diffraction analysis demonstrated that at the early stages of irradiation (below 1 × 1016 ion/cm2) UO2 films show complete amorphization and beam-induced densification (sintering), resulting in a pore-free disordered film. Prolonged irradiation (5 × 1016 ion/cm2) is shown to trigger a crystallization process at the surface of the films that moves toward the UO2/Al interface, converting the entire amorphous material into a highly crystalline film. This work reports on an entirely different radiation-induced restructuring of the nanoscale UO2 compared to the coarse-grained counterpart. The preparation of thin UO2 films deposited on Al substrates fills an area of national need within the stockpile stewardship program of the National Nuclear Security Administration and fundamental research with actinides. The method reported in this work produces pure, robust, and uniform thin-film actinide targets for nuclear science measurements.

(Invited) High Rate Cycling in ε-VOPO4 with Niobium Substitution for Lithium-Ion Batteries

In order to push the energy density of current commercialized lithium-ion batteries, a second lithium must be incorporated into the cathode host without causing any structural damage during intercalation. ε-VOPO4 is a promising high energy density cathode material for lithium-ion batteries due to its ability to fully reversibly intercalate two Li+ from the two redox transitions of V3+/V4+ and V4+/V5+. As a result, ε-VOPO4 displays a high discharge capacity of 305 mAh/g at C/50 (C = 2 Li) for over 50 cycles. However, this vanadyl phosphate material experiences poor Li+ kinetics which impedes its high rate capability at the high voltage plateau. In this work, we determine if niobium substitution can improve the electrochemistry of ε-VOPO4. Through X-ray diffraction and scanning electron microscopy, we investigate the incorporation of niobium in the structure and the effect on morphology. The analysis of substitution on the electrochemical performance will also be discussed alongside with X-ray absorption spectroscopy to confirm the oxidation states of the transition metals during cycling. This research is supported as part of the NorthEast Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0012583. CS gratefully acknowledges the financial support from Graduate Assistance in Areas of National Need (GAANN) Fellowship and Binghamton University Provost's Doctoral Summer Fellowship.

Small footprint head-related transfer function measurement apparatus for binaural heads utilizing one loudspeaker

Apparatuses for measuring head-related transfer-functions (HRTFs) often require large anechoic spaces with one or more arcs of loudspeakers. A measurement setup to obtain the HRTF of a Brüel & Kjær HATS 4100-D binaural head was designed and implemented that utilizes one loudspeaker in a 1309 ft3 anechoic space with 18 in. wedges. By rotating the HATS along two axes, the characterization of many look directions can be achieved. The HATS can be rotated about the axis through the center of the ears via a turntable, and the yaw of the HATS can be adjusted via mounting gear on custom framing. HRTF measurements were completed using both maximum-length sequence and sine sweep signals in order to compare the two techniques. Comparisons between the measured 4100-D HRTF and the HRTF of a similar B&K binaural head will be discussed, as well as plans to use the 4100-D HRTF to compare binaural room impulse responses (RIRs) with spatial RIRs obtained with a spherical microphone array. [Work supported by a Graduate Assistance in Areas of National Need (GAANN) Fellowship.]

Regular Physical Activity Can Prevent the Oncogenic Effects of Lifestyle-Associated Advanced Glycation End Products

Abstract Objectives Lifestyle factors such as a sedentary lifestyle, obesity and a diet consisting of foods high in protein, fat, and highly processed foods contribute to the accumulation of advanced glycation end products (AGEs). AGE pathogenic effects are mediated through modification of protein function, genetic fidelity, stress responses, and cellular signaling pathways which can promote the development of a variety of chronic diseases. However, a gap in the literature exists on the role of dietary AGE in cancer progression and the potential impact of physical activity (PA) to negate such effects. Given the links between lifestyle and AGEs, we propose that a diet high in AGEs can accelerate prostate cancer progression and can be reversed by PA. Methods Xenograft and spontaneous prostate cancer mouse models were utilized to assess the effects of dietary AGE on prostate tumor growth. Mice were exposed to PA on an Animal Treadmill for 1 hr, 5 days a week to assess the impact on dietary AGE mediated tumor progression. Tumor and prostate tissue were collected for histology, and Western Blot analysis. PBMCs were isolated from endpoint blood draws for flow cytometric analysis. Results We found that chronic consumption of AGEs leads to a 3-fold increase in tumor growth in xenograft mice, accompanied by decreased expression of AR, increased expression of MYC, RAGE, and AGE as well as cell proliferation. In the spontaneous prostate cancer model chronic consumption of AGE resulted in increased progression towards high grade PIN and carcinoma when compared to l mice. IHC showed that the high AGE fed mice had increased recruitment of macrophages to PIN lesions. Mice in the PA arm showed a decrease in tumor growth (xenograft) and delayed progression (spontaneous). This was observed in all diet groups, but was most significant in the dietary AGE mice. Conclusions Our studies support the concept that AGEs represent a biological consequence of lifestyle factors that promote cancer progression, and that PA may alleviate these effects. This may have the greatest impact in African American populations who have worse outcomes in prostate cancer, and where a lack of PA, poor diet, and high obesity rates are more prevalent. Funding Sources Bradley Krisanits was supported by Hollings Cancer Center Pre-Doctoral Fellowship (MUSC), Graduate Assistance in Areas of National Need (US Dept. of Ed.), and U54 CA21096.

Molybdenum Substituted Vanadyl Phosphate ε-VOPO4 for Lithium-Ion Batteries

Maintaining the structural reversibility of multiple electron transfer cathodes is a challenge one has to address in order to increase the energy density of current lithium-ion batteries. ε-VOPO4 is a promising cathode material with two redox transitions of V3+/V4+ and V4+/V5+ at about 2.5 and 4 V, respectively. However, the reversibility and cycling stability is compromised with more than one lithium cycling. The goal of this work is to investigate if the substitution of molybdenum can enhance the electrochemical performance of ε-VOPO4. We have focused on molybdenum because it is predicted by the first-principle calculations to display multiple redox potentials in useful voltage window and to form relatively stable substituted ε-VOPO4 phases. We have refined the synthesis method, where by changing a solvent we can control morphology and obtain either loose uniform 100 nm particles, or make those particles form secondary micron-sized spheres. Combing the analysis of X-ray diffraction, and inductively coupled plasma mass spectrometry, we have determined the limits of molybdenum substitution in the structure. The effects of the substitution and morphology on the electrochemical performance will be discussed. This research is supported as part of the NorthEast Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0012583. CS gratefully acknowledges the financial support from Graduate Assistance in Areas of National Need (GAANN) Fellowship and Binghamton University Provost's Doctoral Summer Fellowship.

Composition Dependence of Glucose Oxidation at Mediated Glucose Oxidase Bioanodes

In mediated enzyme electrodes, electrons are transferred between the enzyme and electrode surface via a redox species [1]. Previous studies have documented the parameters affecting mediated GOx electrodes and the effect of the composition, mediator structure, pH etc [2]. Our previous work describes the optimization of mediator redox potential for a laccase-catalyzed oxygen reduction electrode [3]. This result leads us to our current research, focused on modelling the composition dependence of the electrode structure, in terms of the balance between loadings of enzyme and mediator.The electrode under study is a 3 mm diameter glassy carbon rotating disk electrode, modified with a film consisting of glucose oxidase crosslinked with poly(N-VI12[Os(bpy)2Cl]+/2+. The electrochemistry of this electrode, both in terms of mediator redox kinetics and glucose oxidation at pH 7, is studied as a function of GOx, mediator, and crosslinker mass loading. Fig. 1 summarizes cyclic voltammetry (glucose-free) and polarization curves (with glucose) of the modified electrode at a total loading of 0.726 mg cm-2. Glucose-free peak current remains steady at low GOx content, decreasing as mediator content diminishes. An optimum glucose conversion current density is found at 40 wt% GOx, where the catalytic and electron transport properties are balanced.A mathematical model is used to predict the electrode activity. A key consideration is the film thickness, ℓ, which is assumed to vary according to: ℓ = km γm + ke γewhere γ m and γ e are the mass loadings of mediator and enzyme, respectively, and k m and k e represent the effective densities of each component. Electrode thickness is measured independently and correlated to component loading, yielding estimates for the effective densities. This model is correlated to independent measurements of thickness using applied force microscopy (AFM) and profilometry, and the effect of film swelling is considered by experiments with both dry and wet films, applied by both drop deposition and spin coating (Figure 2). ACKNOWLEDGEMENT The authors thank the U.S. Dept. of Education for partial support of this work through a Graduate Assistantship in Areas of National Need (GAANN) fellowship for YF. REFERENCES 1. S. C. Barton, J. Gallaway and P. Atanassov, Chem. Rev., 104, 4867-4886 (2004).2. N. Mano, F. Mao, and A. Heller, J. Electroanal. Chem., 574, 347–357 (2005). 3. J. W. Gallaway and S. Calabrese Barton, J. Am. Chem. Soc., 130, 8527-8536 (2008).

Multidisciplinary Subsurface Remediation Courses: Fundamentals, Experiments, and Design Projects

AbstractSubsurface pollution is an important issue from both economic and environmental perspectives, and the education of professionals with technical backgrounds for addressing this issue is an area of national need. In situ remediation of subsurface pollution is a challenging scientific and engineering problem that is well suited to multidisciplinary problem‐solving approaches. Quantitative design guidance, appropriate textbook instruction, and hands‐on experimental activities are not currently available at most academic institutions. We developed and implemented a set of two courses, one stressing fundamentals in conjunction with design issues, and the other focussing on engineering design aspects of several innovative subsurface remediation technologies. Course materials were derived from our combined multidisciplinary research experiences, coupling physical, chemical, geological, and biological approaches to remediate subsurface pollution. We equipped a laboratory to conduct remediation experiments on a range of scales. These experiments demonstrate fundamental soil and groundwater transport processes, provide design parameters, and yield data for comparing remediation technologies and testing mathematical models. In addition to course evaluations, the project was reviewed and improved by an external curriculum advisory committee.

Peer review and national need

In this paper a quantitative look is taken at some of the latent conflicts between the Canadian government's changing expectations of university research and the peer review process by which the Natural Sciences and Engineering Research Council (NSERC), the major funder of scientific research in the universities, allocates its resources. Focusing on the granting histories of individual grantees, it is shown that, statistically, an individual's funding level is a function of the period of time over which he has been funded by the Council. Studies of other systems of decision making make these findings unsurprising in that they reflect the incremental outcomes of group decisions. However, the do point to the structural problems inherent in a top-down approach to stimulating research in areas of national need within a system involving diffuse focal points for decision making. If future government funding is to be ensured, it will be important to either clarify expectations in order to take account of the traditional autonomy of research councils or, if need is to be explicitly defined as customer oriented, to explore alternative funding mechanisms.