Graduate Research Fellowship Research Articles

Towards High Performance Non-Aqueous Flow Cells

Non-aqueous redox flow batteries (NRFB) have opened a new pathway towards achieving economically viable grid-level energy storage1. As such, a number of studies have reported on the electrochemical behavior of newly developed active species, salt, and solvent combinations (i.e. Brushett et al.2, Escalante-Garcia et al.3, etc.). Most of these redox chemistries, however, have been demonstrated only in beaker cells or un-optimized flow cells; system-level studies toward grid-scale applications have yet been realized. In order to meet aggressive grid storage cost targets, NRFB’s must meet the following power requirements: 3.5 V, 130 mA cm-2, 91% voltaic efficiency4. Hence, designing high performance non-aqueous flow cells tailored for different chemistries becomes a daunting task given the breadth of available chemistries and lack of materials properties (i.e. viscosity) knowledge required for cell design. To ease the design process, this study demonstrates a chemistry-agnostic design cycle for non-aqueous redox flow batteries. Specifically, this design cycle will specify flow field geometries and porous electrode materials properties, which optimize the power output and voltaic efficiency of an unspecified NRFB chemistry. First, transport through interdigitated flow fields is modeled (Figure 1) to predict polarization as a function of various dimensionless groups. This modeling study develops guidelines for geometry and flow conditions as a function of materials properties in order to optimize electrochemical performance. Second, a single-electrolyte study5 (Figure 1) is employed to verify the impact of cell design on the cell performance for model active compounds (i.e., TEMPO6). The single-electrolyte configuration also allows us to study cell performance at fixed states of charge by collecting polarization and impedance data at varying flow rates. Ultimately, this experimental technique will verify trends discovered through the transport modeling. This modeling-experimental approach creates a tool for predicting optimized cell architectures given a set of input materials and chemical properties. Acknowledgments We gratefully acknowledge the financial support of the Joint Center for Energy Storage Research and the National Science Foundation Graduate Research Fellowship Program.

What's NORMal for Fracking? Estimating Total Radioactivity of Produced Fluids.

Naturally occurring radioactive materials (NORM) found in liquid wastes from hydraulic fracturing are an emerging environmental health concern.1 The heavily drilled Marcellus Shale, for example, contains isotopes of radium, polonium, and lead.2,3 However, the few studies that have focused on NORM in fracking wastewater (produced fluids) have reported on a single element—radium.4,5 In this issue of EHP, researchers estimate total reactivity for a mixture of isotopes present in liquid fracking waste from the Marcellus Shale.3 Decay chains—the series of transformations that radionuclides undergo until a stable isotope is produced—are important in planning for the treatment, management, and disposal of radioactive waste.6 Long-lived radioactive elements (such as 226radium) transform into shorter-lived decay products (such as 210lead and 210polonium). Some decay products approach the same radioactivity concentration as the parent radionuclide in a matter of days, while others do so over many decades. In heavily drilled areas like the Marcellus Shale region, fracking activities often take place near homes and workplaces. For the study, researchers at the University of Iowa modeled how concentrations of radionuclides in fracking waste, and thus levels of radioactivity, would change over time. The researchers obtained a sample of fracking wastewater collected from the Marcellus Shale region in 2012 and sealed in a 200-liter drum. They used gamma and alpha spectrometry to measure existing levels of radionuclides in the sealed sample. Using models to account for radioactive decay and ingrowth (increasing concentrations of decay products), the researchers estimated how the total radioactivity concentration of the produced fluids would change in the foreseeable future. “Much of the work we present here was used to develop and validate a rapid radioactivity measurement method for a federal agency,” says lead author Andrew Nelson, a Presidential Graduate Research Fellow and PhD candidate in human toxicology. “We had to have a controlled environment so we could be sure what we were measuring and confident in our analyses. If we left the cap open always, the values would be changing unpredictably.” Under the closed-system conditions, the researchers estimated that the radioactivity concentration would increase by a factor of more than five within 15 days as a result of radioactive ingrowth. They measured an increase in the decay products 210lead and 228thorium in the closed system, and they predicted that radioactivity would continue to increase for more than 100 years with the formation of the decay products 210lead and 210polonium. “We know so little about the extent to which these contaminants represent major health concerns,” says James Burch, an associate professor in the University of South Carolina Department of Epidemiology and Biostatistics. “This study lays the foundation for a more detailed investigation of the health impacts of radioactive waste that may be generated from fracking.” Burch was not involved in the current study. Because fracking activities and wastewater disposal often take place in close proximity to where people live and work, there’s a potential for human exposure, according to Burch. “The technology is vastly outpacing what we know about the health effects,” he says. A few cases of radioactive contamination outside of wastewater treatment facilities have been documented. In one notable example, researchers studied wastewater effluent discharged by the Josephine Brine Treatment Facility in Pennsylvania. In stream sediments near the facility, the researchers measured concentrations of 226radium that were approximately 200 times higher than would normally be expected.7 The authors of the current study conclude that future studies and risk assessments should include radium decay products in assessing the potential for environmental contamination from fracking”5 Nelson calls the current research a “conversation starter” that aims to inform risk assessment and waste handling. “If you don’t have an accurate measurement of the radiochemical parameters, you can’t have an accurate dose assessment,” he says. While the experimental design represents a starting point, it’s unclear how applicable the projections would be under real-world conditions where fluids are being moved around, handled, and exposed to the air, says Arthur Rose, an environmental geochemist and professor emeritus at Pennsylvania State University, who was not involved in the research. “In this study you have a worst-case scenario in which all the decay products remain in the water,” Rose says. “A more likely scenario would be that some of the radon would escape into the air. Future studies need to look at radon release.” In ongoing field studies, Nelson and colleagues are applying new methods they developed to real-world scenarios. One study is looking at how radioactivity concentrations of naturally occurring radionuclides and their decay products change over time at a wastewater treatment facility that handles unconventional drilling waste.

TU‐CD‐304‐05: 4Ï€ Non‐Coplanar Radiotherapy: From Mathematical Modeling to Clinical Implementation

Purpose:To develop and clinically implement 4π radiotherapy, an inverse optimization platform that maximally utilizes non‐coplanar intensity modulated radiotherapy (IMRT) beams to significantly improve critical organ sparing.Methods:A 3D scanner was used to digitize the human and phantom subject surfaces, which were positioned in the computer assisted design (CAD) model of a TrueBeam machine to create a virtual geometrical model, based on which, the feasible beam space was calculated for different tumor locations. Beamlets were computed for all feasible beams using convolution/superposition. A column generation algorithm was employed to optimize patient specific beam orientations and fluence maps. Optimal routing through all selected beams were calculated by a level set method. The resultant plans were converted to XML files and delivered to phantoms in the TrueBeam developer mode. Finally, 4π plans were recomputed in Eclipse and manually delivered to recurrent GBM patients.Results:Compared to IMRT utilizing manually selected beams and volumetric modulated arc therapy plans, markedly improved dosimetry was observed using 4π for the brain, head and neck, liver, lung, and prostate patients. The improvements were due to significantly improved conformality and reduced high dose spillage to organs mediolateral to the PTV. The virtual geometrical model was experimentally validated. Safety margins with 99.9% confidence in collision avoidance were included to the model based model accuracy estimates determined via 300 physical machine to phantom distance measurements. Automated delivery in the developer mode was completed in 10 minutes and collision free. Manual 4 π treatment on the GBM cases resulted in significant brainstem sparing and took 35–45 minutes including multiple images, which showed submillimeter cranial intrafractional motion.Conclusion:The mathematical modeling utilized in 4π is accurate to create and guide highly complex non‐coplanar IMRT treatments that consistently and significantly outperform human‐operator‐created plans. Deliverability of such plans is clinically demonstrated.This work is funded by Varian Medical Systems and the NSF Graduate Research Fellowship DGE‐1144087.

SU-D-BRB-06: Treating Glioblastoma Multiforme (GBM) as a Chronic Disease: Implication of Temporal-Spatial Dose Fractionation Optimization Including Cancer Stem Cell Dynamics

Purpose: To explore the feasibility of improving GBM treatment outcome with temporal-spatial dose optimization of an ordinary differential equation (ODE) that models the differentiation and distinct radiosensitivity between cancer stem cells (CSC) and differentiated cancer cells (DCC). Methods: The ODE was formulated into a non-convex optimization problem with the objective to minimize remaining total cancer cells 500 days from the onset of radiotherapy when the total cancer cell number was 3.5×10⁷, while maintaining normal tissue biological effective dose (BED) of 100Gy resulted from standard prescription of 2Gyx30. Assuming spatially separated CSC and DCC, optimization was also performed to explore the potential benefit from dose-painting the two compartments. Dose escalation to a sub-cell-population in the GTV was also examined assuming that a 2 cm margin around the GTV allows sufficient dose drop-off to 100Gy BED. The recurrence time was determined as the time at which the total cancer cell number regrows to 109 cells. Results: The recurrence time with variable fractional doses administered once per week, bi-week and month for one year were found to be 615, 593 and 570 days, superior to the standard-prescription recurrence time of 418 days. The optimal dose-fraction size progression for both uniform and dose-painting to the tumor is low and relatively constant in the beginning and gradually increases to more aggressive fractions at end of the treatment course. Dose escalation to BED of 200Gy to the whole tumor alongside with protracted weekly treatment was found to further delay recurrence to 733 days. Dose-painting of 200 and 500Gy BED to CSC on a year-long weekly schedule further extended recurrence to 736 and 1076 days, respectively. Conclusion: GBM treatment outcome can possibly be improved with a chronic treatment approach. Further dose escalation to the entire tumor or CSC targeted killing is needed to achieve total tumor control. This work is supported by the NSF Graduate Research Fellowship (DGE-1144087).

Using ecological theory to develop recovery criteria for an endangered butterfly

Using ecological theory to develop recovery criteria for an endangered butterfly

ASM News for May 2015

Abstract News about ASM members, chapters, events, awards, conferences, affiliates, and other society activities. Topics include: The International Organization on Shape Memory and Superelastic Technologies (SMST) announces a graduate research fellowship; ASM President Sunniva Collins describes the benefits of participating in local ASM chapter activities; emerging professional Rachel Bethancourt recounts her experiences in navigating a workplace alongside experienced personnel.

Cis regulatory effects on A-to-I RNA editing in related Drosophila species.

Adenosine-to-inosine RNA editing modifies maturing mRNAs through the binding of adenosine deaminase acting on RNA (Adar) proteins to double-stranded RNA structures in a process critical for neuronal function. Editing levels at individual editing sites span a broad range and are mediated by both cis-acting elements (surrounding RNA sequence and secondary structure) and trans-acting factors. Here, we aim to determine the roles that cis-acting elements and trans-acting factors play in regulating editing levels. Using two closely related Drosophila species, D. melanogaster and D. sechellia, and their F1 hybrids, we dissect the effects of cis sequences from trans regulators on editing levels by comparing species-specific editing in parents and their hybrids. We report that cis sequence differences are largely responsible for editing level differences between these two Drosophila species. This study presents evidence for cis sequence and structure changes as the dominant evolutionary force that modulates RNA editing levels between these Drosophila species.

Mechanisms of Mammalian Middle Ear Ossicle Transition from the Reptilian Jaw Joint

During synapsid evolution, postdentary elements in the reptilian jaw transitioned into the middle ear of early mammals. Separation from the dentary allowed unconstrained evolution of the middle ear ossicles, resulting in increased hearing sensitivity and amplified frequency range. Given the importance of such an innovation, it is essential to understand the evolutionary pathway that led to the current phenotype, as this has implications for understanding the development of all mammals. Using an extant model system, Monodelphis domestica, we investigate the developmental basis of the definitive mammalian middle ear. We utilize micro‐CT imaging to characterize the morphological events underpinning the transition, cryosectioning and immunohistochemistry to identify cellular processes behind the morphological events, and laser capture microscopy followed by RNA Sequencing to identify changes in gene expression driving the cellular processes. Among our findings are: decreasing size and rearward movement of the middle ear ossicles appear to be false illusions created by the continued growth and expansion of the surrounding skull elements; separation of Meckel's cartilage from the malleus, occurring at postnatal day 20, is facilitated by apoptosis and is a prerequisite for the onset of hearing; separation and functional changes are due to alterations in timing and expression levels of key genes.Supported by NSF Graduate Research Fellowship and Doctoral Dissertation Improvement Grant.

Pharmaceutical Control of the Microbiome

The intestinal microbiota encode millions of genes that represent unique pharmaceutical targets for human diseases from neurological disorders to drug toxicity. We are interested in the role intestinal microbiota play in reactivating compounds that have been inactivated through glucuronidation. In particular, the chemotherapy drug CPT‐11 is inactivated by UGTs in the liver and then reactivated by bacterial Β‐glucuronidases in the large intestine resulting in dose‐limiting diarrhea. We characterized the structure and function of three Β‐glucuronidase enzymes from different bacteria and showed that a key bacterial loop allows for selective inhibition of these enzymes versus the human enzyme orthologue. We have developed, using chemical biology, novel inhibitors that potently and non‐lethally inhibit bacterial Β‐glucuronidases and stop drug toxicity of CPT‐11 in mouse models. We also examined the toxicity caused by the nonsteroidal anti‐inflammatory drugs (NSAIDs) diclofenac, ketoprofen, and indomethacin. These drugs were also hypothesized to be reactivated by bacterial Β‐glucuronidases, resulting in the acute longitudinal small intestinal ulcers that causer 40% of NSAID‐associated deaths. We found our inhibitors are also effective against this type of drug toxicity and alleviated the intestinal ulcers seen in mouse models. Thus, we have established that the microbiome contains targets for non‐lethal pharmacology to address acute problems of human health.Funding from NIH CA98468 and NSF Graduate Research Fellowship

Effect of milling atmosphere on structural and magnetic properties of Ni–Zn ferrite nanocrystalline**Project supported by the University Putra Malaysia Graduate Research Fellowship Section.

Powder mixtures of Zn, NiO, and Fe2O3 are mechanically alloyed by high energy ball milling to produce Ni–Zn ferrite with a nominal composition of Ni0.36Zn0.64Fe2O4. The effects of milling atmospheres (argon, air, and oxygen), milling time (from 0 to 30 h) and heat treatment are studied. The products are characterized using x-ray diffractometry, field emission scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy, and transmitted electron microscopy. The results indicate that the desired ferrite is not produced during the milling in the samples milled under either air or oxygen atmospheres. In those samples milled under argon, however, Zn/NiO/Fe2O3 reacts with a solid-state diffusion mode to produce Ni–Zn ferrite nanocrystalline in a size of 8 nm after 30-h-milling. The average crystallite sizes decrease to 9 nm and 10 nm in 30-h-milling samples under air and oxygen atmospheres, respectively. Annealing the 30-h-milling samples at 600 °C for 2 h leads to the formation of a single phase of Ni–Zn ferrite, an increase of crystallite size, and a reduction of internal lattice strain. Finally, the effects of the milling atmosphere and heating temperature on the magnetic properties of the 30-h-milling samples are investigated.

Assessing childhood malnutrition in Haiti: Is the United Nations Millennium Goal #4 being met?

and the level of cognitive function at a school in Guayaquil, Ecuador. Demographic data was also collected from 175 students between the ages of 5 to 11 years old. Exclusions were those children with a known mental disability. Each student had their hemoglobin levels measured using the STAT-Site Hgb Meter. Cognitive function was measured by the Raven Colored Progressive Matrices (CPM) exam. The CPM exam measures nonverbal intelligence and was selected because it is language independent. Outcomes & Evaluation: The correlation between the level of anemia and the level of cognitive function was .001 showing no correlation. A T-test from the CPM score also showed no significant difference. Of significance (Beta1⁄40.16, t1⁄4 2.5, p1⁄4 0.01) was the correlation between cognitive function and monthly household income. Going Forward: Although the original hypothesis of anemia negatively affecting cognitive function was disproved, it is worthwhile to further investigate the relation between household income and cognitive function. Time spent with parent and child doing homework, the opinion of parents and others in the household on the value of education, and the level of education of the parents are a few of the items that could be considered. Higher incomes resulting in improved nutrition could also contribute to higher hemoglobin levels and higher CPM scores. All of these variables should be studied to show the correlation between household income and cognitive function in children. Funding: Funding was provided through Brigham Young University’s Graduate Research Fellowship. Abstract #: 02SEDH005

Intimate partner violence and condom versus other modern contraception use among married women in rural India

and the level of cognitive function at a school in Guayaquil, Ecuador. Demographic data was also collected from 175 students between the ages of 5 to 11 years old. Exclusions were those children with a known mental disability. Each student had their hemoglobin levels measured using the STAT-Site Hgb Meter. Cognitive function was measured by the Raven Colored Progressive Matrices (CPM) exam. The CPM exam measures nonverbal intelligence and was selected because it is language independent. Outcomes & Evaluation: The correlation between the level of anemia and the level of cognitive function was .001 showing no correlation. A T-test from the CPM score also showed no significant difference. Of significance (Beta1⁄40.16, t1⁄4 2.5, p1⁄4 0.01) was the correlation between cognitive function and monthly household income. Going Forward: Although the original hypothesis of anemia negatively affecting cognitive function was disproved, it is worthwhile to further investigate the relation between household income and cognitive function. Time spent with parent and child doing homework, the opinion of parents and others in the household on the value of education, and the level of education of the parents are a few of the items that could be considered. Higher incomes resulting in improved nutrition could also contribute to higher hemoglobin levels and higher CPM scores. All of these variables should be studied to show the correlation between household income and cognitive function in children. Funding: Funding was provided through Brigham Young University’s Graduate Research Fellowship. Abstract #: 02SEDH005

Substrate Binding Effects of Carbohydrate Binding Modules on the Catalytic Activity of a Multifunctional Cellulase

CelE from Clostridium thermocellum is a glycoside hydrolase family 5 enzyme that has broad specificity for hydrolysis of plant biomass polysaccharides, particularly cellulose, xylan, and mannan. A fusion of CelE with the well-studied carbohydrate binding module CBM3a was created, CelE_CBM3a, and this construct alone was able to give high-yield hydrolysis of both cellulose and hemicellulose in pretreated plant biomass. In this study, thirty-nine different CBMs from the C. thermocellum genome were fused to GFP, and the specific binding interactions of the robotic cell-free translated GFP_CBM constructs were determined with a panel of soluble and insoluble substrates. Most CBMs tested were able to bind at least one substrate, and several GFP_CBMs displayed unanticipated binding capabilities. We also asked whether these CBMs could yield different catalytic capabilities when fused to the multifunctional enzyme, CelE. Different CelE_CBM fusions were also expressed using robotic cell-free translation, and our results show that some CBMs enhanced cellulose hydrolysis through specific interaction between the CBM domain and polysaccharide. In addition, different CelE_CBM fusions gave lichenan-, xylan-, mannan-, and biomass-specific improvements in the catalytic activities. The methods described here provide a useful system that can be used to test the function of other CBM domains and to assist in the design and testing of new engineered enzyme formats.This work was supported by the DOE Great Lakes Bioenergy Research Center (DOE Office of Science BER DE-FC02-07ER64494) and the University of Wisconsin-Madison's Science and Medicine Graduate Research Scholars Advanced Opportunity Fellowship (SciMed GRS AOF) Program (J.A.W.), the National Institute of General Medical Sciences Molecular Biophysics Training Program (NIH T32 GM08293, J.A.W.), and the National Science Foundation Graduate Research Fellowship Program (DGE-1256259 to J.A.W.).

Alternative Synthesis Pathways of Electrolytes for Magnesium-Ion Batteries

Battery chemistries based on multivalent ions are beginning to receive considerable attention from both researchers and industry because it is possible to transfer more than one electron per metal atom. Magnesium-ion systems in particular have been the subject of a great deal of research because of the ability to use metallic magnesium anodes for high energy density, and as such the capacity of the cell is limited only by the cathode material. One of the biggest hurdles that is limiting progress in this area is the development of electrolytes that facilitate the reversible deposition of magnesium metal. The current state of the art electrolytes are based on of Grignard-derived Lewis bases paired with Lewis acids such as aluminum chloride.[1] The presence of chloride ions in these solutions has proven to be problematic because they cause pitting and corrode parts commonly used in coin cells, namely stainless steel.[2] In recent years, other researchers have explored various alkoxide-based electrolytes, but these solutions also employ Grignard reagents.[3–5] As such, it is imperative that researchers identify pathways that can result in halide-free electrolyte solutions.We have identified a synthesis pathway to produce viable Mg electrolytes that does not require Grignard reagents. The Mg source is derived from various alcohols in a simple one-step reaction. The electrolyte is composed of the alcohol-based magnesium compound and a Lewis acid (AlCl3) in an ethereal solvent. Figure 1a shows the cyclic voltammetric behavior of the electrolyte solution as a function of the amount of AlCl3 in the system, and that the optimal molar ratio of the two components is in the range of a 1:1 or 1:2 mixture. The oxidation limit of the 1:1 mixture is as high as 2.9 V vs. Mg, which is comparable to other alcohol-based electrolytes in the literature. Additionally, Figure 1b and 1c show EDX and SEM data indicating that the resulting magnesium deposits are of good purity. We will discuss the effects of different Lewis acids on these magnesium sources, using NMR and Raman spectroscopies to determine speciation in a range ethereal solvents. Deposition behavior and conductivity as a function of solution composition will be discussed.REFERENCES[1] Aurbach, D.; Suresh, G. S.; Levi, E.; Mitelman, a.; Mizrahi, O.; Chusid, O.; Brunelli, M. Adv. Mater. 2007, 19, 4260–4267.[2] Muldoon, J.; Bucur, C. B.; Oliver, A. G.; Zajicek, J.; Allred, G. D.; Boggess, W. C. Energy Environ. Sci. 2013, 6, 482–487.[3] Liao, C.; Guo, B.; Jiang, D.; Custelcean, R.; Mahurin, S. M.; Sun, X.-G.; Dai, S. J. Mater. Chem. A 2014, 2, 581–584.[4] Nelson, E. G.; Kampf, J. W.; Bartlett, B. M. Chem. Commun. 2013, 2, 3–5.[5] Wang, F.; Guo, Y.; Yang, J.; Nuli, Y.; Hirano, S. Chem. Commun. 2012, 48, 10763–10765.ACKNOWLEDGEMENTSSupport was provided by the National Science Foundation through the Graduate Research Fellowship Program. Additional support was provided by the ISN North American Low Carbon Emission Self-Sufficiency Fund from the Andlinger Center for Energy and the Environment at Princeton University.

The first phytosaur (Diapsida, Archosauriformes) from the Late Triassic of the Iberian Peninsula

Click to increase image sizeClick to decrease image size ACKNOWLEDGMENTSWe thank the DFG (grant BU 2587/1-1), Jurassic Foundation, Lamont-Doherty Earth Institute Climate Center (Columbia University), Chevron Student Initiative Fund (Columbia University), American Museum of Natural History (M. Norell), and the UMR 7207 of the CNRS for supporting this project. We thank J. Dzik and R. Bronowicz (ZPAL) and R. Schoch (SMNS) for access to specimens in their care. During the course of this project S.L.B. was funded by an NSF Graduate Research Fellowship and Doctoral Dissertation Improvement Grant (DEB-1110357). R.J.B. was supported during completion of this work by an Emmy Noether Programme Award from the DFG (BU 2587/3-1). We thank A. Kasprak (who discovered the specimen), F. Lopes, E. Tschopp, C. Hendrickx, and J. Marinheiro for being part of our field team. We thank the Câmara Municipal de Loulé, Junta de Freguesia de Alte, and Câmara Municipal de Silves for local support, and V. Duarte and N. Lopez for careful laboratory preparation. M. Stocker and M. Maisch provided useful review comments.Handling editor: Emily Rayfield

Tapinocephalids (Therapsida, Dinocephalia) from the Permian Madumabisa Mudstone Formation (Lower Karoo, Mid-Zambezi Basin) of southern Zambia

Click to increase image sizeClick to decrease image size ACKNOWLEDGMENTSOur research in Zambia has been supported by the National Geographic Society (CRE 8571-088 to J.S.S., CRE 8961-11 to C.A.S.), with additional support from The Grainger Foundation and the Field Museum/IDP, Inc. African Partner's Program (to K.D.A.), and NSF EAR-1337569 (to C.A.S.), and EAR-1337291 (to K.D.A.). B.R.P. was supported by a NSF Graduate Research Fellowship. We thank K. Mwamulowe and J. Museba (NHCC) for assistance in arranging and carrying out the field work. Fossil preparation was skillfully performed by G. Livingston and B. Crowley (Burke Museum). We acknowledge the fine illustrations made by M. Schumacher in Figure 3 and B. Strack (Field Museum) for assistance with the electron micrograph in Figure 1. Finally, we thank J. Cisneros, M. Day, I. Nyambe, and B. Rubidge for their helpful reviews.Handling editor: Bruce Rubidge.

WE‐E‐BRE‐08: Impact of IUdR in Rat 9L Glioma Cell Survival for 25–35 KeV Photo‐Activated Auger Electron Therapy

Purpose:To determine the biological effect from Auger electrons with 9% and 18% iododeoxyuridine (IUdR) incorporated into the DNA of rat 9L glioma cells at photon energies above and below the K‐edge of iodine (33.2 keV).Methods:Rat 9L glioma cell survival versus dose curves with 0%, 9%, and 18% thymidine replacement with IUdR were measured using four irradiation energies (4 MV x‐rays; monochromatic 35, 30, and 25 keV synchrotron photons). For each of 11 conditions (Energy, %IUdR) survival curves were fit to the data (826 cell cultures) using the linear‐quadratic model. The ratio of doses resulting in 10% survival gave sensitization enhancement ratios (SER10) from which contributions due to linear‐energy transfer (LET), radiosensitization (RS), and Auger effect (AE) were extracted.Results:At 35, 30, and 25 keV, SER10,LET values were 1.08±0.03, 1.22±0.02, and 1.37±0.02, respectively. At 4 MV SER10,RS values for 9% and 18% IUdR were 1.28±0.02 and 1.40±0.02, respectively. Assuming LET effects are independent of %IUdR and radiosensitization effects are independent of energy, SER10,AE values for 18% IUdR at 35, 30, and 25 keV were 1.35±0.05, 1.06±0.03, and 0.98±0.03, respectively; values for 9% IUdR at 35 and 25 keV were 1.01±0.04 and 0.82±0.02, respectively.Conclusion:For 18% IUdR the radiosensitization effect of 1.40 and the Auger effect of 1.35 at 35 keV are equally important to the combined effect of 1.90. No measureable Auger effect was observed for energies below the K‐edge at 20 and 25 keV, as expected. The insignificant Auger effect at 9% IUdR was not expected. Additional data (40–70 keV) and radiobiological modeling are being acquired to better understand the energy dependence of Auger electron therapy with IUdR.Funding support in part by the National Science Foundation Graduate Research Fellowship Program and in part by Contract No. W81XWH‐10‐1‐0005 awarded by the U.S. Army Research Acquisition Activity. This paper does not necessarily reflect the position or policy of the Government, and no official endorsement should be inferred.

Corrections to “Controlling the Interface Dynamics at Au Nanoparticle – Oxide Interfaces” [Jan 12 12-15

In the above-named work [ibid., vol. 11, no. 1, pp. 12-15, Jan. 2012], the first paragraph of the first footnote should have read as follows: Manuscript received July 19, 2010; accepted May 9, 2011. Date of publication June 27, 2011; date of current version January 11, 2012. This work was supported in part by the U.S. Department of Energy, Office of Basic Science under Grant DE-FG02-00ER45813-A000 in the Bonnell Group for conducting experimental work and by the Nano/Bio Interface Center through the National Science Foundation under Grant IGERT DGE02-21664 and NSEC DMR08-32802. The work of L. Y. Kraya was supported by a graduate research fellowship from the National Science Foundation. The review of this paper was arranged by Associate Editor E.T. Yu.

N-Cadherin-Mediated Cell Signaling in Nucleus Pulposus Cells of the Intervertebral Disc

Introduction Immature nucleus pulposus (NP) cells of the intervertebral disc (IVD) are large, vacuolated cells that form cell clusters with strong cell-cell interactions.1 With maturation and aging, NP cells lose their ability to form these cell clusters, with aging-associated changes in NP cell phenotype, morphology, and proteoglycan synthesis that may contribute to IVD degeneration.2-4 Therefore it is important to understand the mechanisms governing immature NP cell cluster behavior toward the goal of revealing factors that can promote immature, healthy NP cell phenotypes. Prior work has shown healthy, immature NP cells preferentially bind laminin proteins, exhibit potential for cell cluster formation, and maintain matrix production when cultured upon soft, laminin-containing substrates.2 N-cadherin has been identified as a cell-cell adhesion marker that is present in immature NP cells, but disappears with age.5-6 The goal of this study was to determine if N-cadherin was an important molecule in regulating cell-cell interactions in immature NP cell cluster formation and to test for a regulatory role in maintaining an immature NP phenotype for IVD cells in vitro. Materials and Methods Porcine nucleus pulposus (NP) cells were isolated from IVD of immature pigs (3-6 mos).2 Laminin-rich substrates were constructed from basement membrane extract (BME, 13.7 mg/mL, Trevigen) to generate soft (300 Pa) or stiff (BME-coated glass, > 2,900 Pa) substrates; similar substrates were constructed of “soft” and “stiff” type I collagen (col 1, 4 mg/mL, Sigma). NP cells were plated (65,000 cells/cm2) on the substrates with the following treatment conditions for up to 4 days: N-cadherin (40 μg/mL) blocking antibody, E-cadherin (20 μg/mL) blocking antibody or no treatment control. NP cells were stained for polymerized F-actin (phalloidin, Invitrogen), anti-N-cadherin (Abcam), or anti-E-cadherin (Abcam) antibodies with propidium iodide nuclei counterstain. Changes in matrix production were analyzed in collected media and recovered cells via biochemical assays for sGAG (DMMB assay) and DNA (picogreen). Additionally, gene expression for immature NP markers, N-cadherin, Brachyury-T, aggrecan and type I collagen, were analyzed via quantitative real-time PCR. Results NP cells cultured upon soft BME substrates maintained their rounded morphology at all times with formation of 3D cell clusters ( Fig. 1A ). On stiff BME and all col 1 substrates, NP cells spread out and attached with formation of numerous actin stress fibers. Higher N-cadherin expression was observed on soft BME compared with all other substrates; E-cadherin expression was absent in porcine NP cells on all substrates. Additionally, significantly higher matrix production was observed on soft BME substrates compared with soft col 1 ( Fig. 1B ), and higher gene expression for NP markers was observed on soft BME substrates compared with all other substrates ( Fig. 1C ). NP cell cluster formation, proteoglycan synthesis and NP marker gene expression on soft BME substrates was influenced by N-cadherin blocking antibody but not E-cadherin blocking antibody ( Fig. 1A -C). [Figure: see text] Conclusion Soft BME substrates promote NP cell clustering in vitro with an associated expression of N-cadherin. In NP cells, it appears that N-cadherin-mediated signaling helps promote matrix production and elevated expression for multiple molecular markers of an immature NP phenotype. Treatment with an N-cadherin blocking antibody resulted in loss of all features of the immature NP cell on soft BME substrates. These findings establish the importance of N-cadherin in mediating immature NP cell cluster formation and maintenance of the immature phenotype. Ongoing studies aim to understand the downstream signaling mechanisms governed by N-cadherin-mediated signaling that promote the immature NP phenotype. Acknowledgments This study was supported with funds from NIH R01EB002263, R01AR047442, R01AR057410, T32GM008555, North Carolina Biotechnology Center, and with the NSF Graduate Research Fellowship. Disclosure of Interest None declared References Trout JJ, Buckwalter JA, Moore KC, Landas SK. Ultrastructure of the human intervertebral disc. I. Changes in notochordal cells with age. Tissue Cell 1982;14(2):359–369 Gilchrist CL, Darling EM, Chen J, Setton LA. Extracellular matrix ligand and stiffness modulate immature nucleus pulposus cell-cell interactions. PLoS ONE 2011;6(11):e27170 Boos N, Weissbach S, Rohrbach H, Weiler C, Spratt KF, Nerlich AG. Classification of age-related changes in lumbar intervertebral discs: 2002 Volvo Award in basic science. Spine 2002;27(23):2631–2644 Buckwalter JA. Aging and degeneration of the human intervertebral disc. Spine 1995;20(11):1307–1314 Minogue BM, Richardson SM, Zeef LA, Freemont AJ, Hoyland JA. Transcriptional profiling of bovine intervertebral disc cells: implications for identification of normal and degenerate human intervertebral disc cell phenotypes. Arthritis Res Ther 2010;12(1):R22 Minogue BM, Richardson SM, Zeef LA, Freemont AJ, Hoyland JA. Characterization of the human nucleus pulposus cell phenotype and evaluation of novel marker gene expression to define adult stem cell differentiation. Arthritis Rheum 2010;62(12):3695–3705

R&D ekes out an increase in FY 2015 budget request

With spending caps in place, President Obama proposes an off-budget fund to support additional R&D. NASA would ground a flying observatory, and DOE would sharply curtail its nonproliferation programs.