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RISS 인기검색어
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- 저자 : O'Day, Elizabeth (검색결과 9 건)
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Wang, Guohui,Um, Wooyong,Wang, Zheming,Reinoso-Maset, Estela,Washton, Nancy M.,Mueller, Karl T.,Perdrial, Nicolas,O’Day, Peggy A.,Chorover, Jon American Chemical Society 2017 Environmental science & technology Vol.51 No.19
<P>The reaction of acidic radioactive waste with sediments can induce mineral transformation reactions that, in turn, control contaminant fate. Here, sediment weathering by synthetic uranium containing acid solutions was investigated using bench-scale experiments to simulate waste disposal conditions at Hanford's cribs (Hanford, WA). During acid weathering, the presence of phosphate exerted a strong influence over uranium mineralogy and a rapidly precipitated, crystalline uranium phosphate phase (meta-ankoleite [K(UO2)(PO4).3H(2)O] was identified using spectroscopic and diffraction-based techniques. In phosphate-free system, uranium oxyhydroxide minerals such as K-compreignacite [K-2(UO2)(6)O-4(OH)(6).7H(2)O] were formed. Single-pass flow-through (SPFT) and column leaching experiments using synthetic Hanford pore water showed that uranium precipitated as meta-ankoleite during acid weathering was strongly retained in the sediments, with an average release rate of 2.67 X 10(-12) mol g(-1) s(-1). In the absence of phosphate, uranium release was controlled by dissolution of uranium oxyhydroxide (compreignacitetype) mineral with a release rate of 1.05-2.42 X 10(-1) mol g(-1) s(-1). The uranium mineralogy and release rates determined for both systems in this study support the development of accurate U-release models for the prediction of contaminant transport. These results suggest that phosphate minerals may be a good candidate for uranium remediation approaches at contaminated sites.</P>
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Rates and mechanisms of uranyl oxyhydroxide mineral dissolution
Reinoso-Maset, Estela,Steefel, Carl I.,Um, Wooyong,Chorover, Jon,O'Day, Peggy A. Pergamon Press 2017 Geochimica et cosmochimica acta Vol.207 No.-
<P><B>Abstract</B></P> <P>Uranyl oxyhydroxide minerals are important weathering products in uranium-contaminated surface and subsurface environments that regulate dissolved uranium (U) concentrations. However, dissolution rates for this class of minerals and associated dissolution mechanisms have not been previously reported for circumneutral pH conditions, particularly for the case of flow through porous media. In this work, the dissolution rates of K- and Na-compreignacite (K<SUB>2</SUB>(UO<SUB>2</SUB>)<SUB>6</SUB>O<SUB>4</SUB>(OH)<SUB>6</SUB>·8H<SUB>2</SUB>O and Na<SUB>2</SUB>(UO<SUB>2</SUB>)<SUB>6</SUB>O<SUB>4</SUB>(OH)<SUB>6</SUB>·8H<SUB>2</SUB>O, respectively) were measured using flow-through columns reacted with two simulated background porewater (BPW) solutions of low and high dissolved carbonate concentration (ca. 0.2 and 2.8mmolL<SUP>−1</SUP>). Column materials were characterized before and after reaction with electron microscopy, bulk chemistry, and EXAFS to identify structural and chemical changes during dissolution and to obtain insight into molecular-scale processes. The reactive transport code CrunchFlow was used to calculate overall dissolution rates while accounting for fluid transport and changes in mineral volume and reactive surface area, and results were compared to steady-state dissolution rate calculations. In low carbonate BPW systems, interlayer K and Na were initially leached from both minerals, and in Na-compreignacite, K and minor divalent cations from the input solution were incorporated into the mineral structure. Results of characterization analyses suggested that after reaction both K- and Na-compreignacite resembled a disordered K-compreignacite with altered surfaces. A 10-fold increase in dissolved carbonate concentration and corresponding increase in pH (from 6.65 to 8.40) resulted in a net removal of 58–87% of total U mass from the columns, compared to <1% net loss in low carbonate BPW systems. Steady-state release of dissolved U was not observed with high carbonate solutions and post-reaction characterizations indicated a lack of development of leached or altered surfaces. Dissolution rates (normalized to specific surface area) were 2.5–3 orders-of-magnitude faster in high versus low carbonate BPW systems, with Na-compreignacite dissolving more rapidly than K-compreignacite under both BPW conditions, possibly due to greater ion exchange (1.57·10<SUP>−10</SUP> vs. 1.28·10<SUP>−13</SUP> molm<SUP>−2</SUP> s<SUP>−1</SUP> [log <I>R</I> =−9.81 and −12.89] and 5.79·10<SUP>−10</SUP> vs. 3.71·10<SUP>−13</SUP> molm<SUP>−2</SUP> s<SUP>−1</SUP> [log <I>R</I> =−9.24 and −12.43] for K- and Na-compreignacite, respectively). Experimental and spectroscopic results suggest that the dissolution rate is controlled by bond breaking of a uranyl group and detachment from polyhedral layers of the mineral structure. With higher dissolved carbonate concentrations, this rate-determining step is accelerated by the formation of Ca-uranyl carbonate complexes (dominant species under these conditions), which resulted in an increase of the dissolution rates. Optimization of both dissolution rate and mineral volume fraction in the reactive transport model to account for U mass removal during dissolution more accurately reproduced effluent data in high carbonate systems, and resulted in faster overall rates compared with a steady-state dissolution assumption. This study highlights the importance of coupling reaction and transport processes during the quantification of mineral dissolution rates to accurately predict the fate of contaminants such as U in porous geomedia.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Compreignacite dissolution rates vary with the interlayer cation (Na>K). </LI> <LI> Detachment of uranyl groups from polyhedral layers is the rate-determining step. </LI> <LI> I
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Syed, O.,Walters, N.J.,Day, R.M.,Kim, H.W.,Knowles, J.C. Elsevier BV 2014 ACTA BIOMATERIALIA Vol.10 No.12
Small intestine submucosa (SIS) has emerged as one of a number of naturally derived extracellular matrix (ECM) biomaterials currently in clinical use. In addition to clinical applications, ECM materials form the basis for a variety of approaches within tissue engineering research. In our preliminary work it was found that SIS can be consistently and reliably made into tubular scaffolds which confer certain potential advantages. Given that decellularization protocols for SIS are applied to sheet-form SIS, it was hypothesized that a tubular-form SIS would behave differently to pre-existing protocols. In this work, tubular SIS was produced and decellularized by the conventional peracetic acid-agitation method, peracetic acid under perfusion along with two commonly used detergent-perfusion protocols. The aim of this was to produce a tubular SIS that was both adequately decellularized and possessing the mechanical properties which would make it a suitable scaffold for oesophageal tissue engineering, which was one of the goals of this work. Analysis was carried out via mechanical tensile testing, DNA quantification, scanning electron and light microscopy, and a metabolic assay, which was used to give an indication of the biocompatibility of each decellularization method. Both peracetic acid protocols were shown to be unsuitable methods with the agitation-protocol-produced SIS, which was poorly decellularized, and the perfusion protocol resulted in poor mechanical properties. Both detergent-based protocols produced well-decellularized SIS, with no adverse mechanical effects; however, one protocol emerged, SDS/Triton X-100, which proved superior in both respects. However, this SIS showed reduced metabolic activity, and this cytotoxic effect was attributed to residual reagents. Consequently, the use of SIS produced using the detergent SD as the decellularization agent was deemed to be the most suitable, although the elimination of the DNase enzyme would give further improvement.
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de Lorenzo, Ví,ctor,Prather, Kristala LJ,Chen, Guo‐,Qiang,O'Day, Elizabeth,von Kameke, Conrad,Oyarzú,n, Diego A,Hosta‐,Rigau, Leticia,Alsafar, Habiba,Cao, Cong,Ji, Weizhi,Okano John Wiley and Sons Inc. 2018 EMBO reports Vol.19 No.4
<P>The UN's Sustainable Development Goals present a challenge for biotechnology to develop new environmentally‐friendly and sustainable products and production processes. </P>
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Genomic Heterogeneity as a Barrier to Precision Medicine in Gastroesophageal Adenocarcinoma
Pectasides, Eirini,Stachler, Matthew D.,Derks, Sarah,Liu, Yang,Maron, Steven,Islam, Mirazul,Alpert, Lindsay,Kwak, Heewon,Kindler, Hedy,Polite, Blase,Sharma, Manish R.,Allen, Kenisha,O'Day, Emily,Lomni American Association for Cancer Research 2018 Cancer discovery Vol.8 No.1
<P>Heterogeneity of actionable genomic alterations among primary and metastatic lesions suggests that biomarker profiling of a single primary tumor site may limit the success of targeted therapy in gastroesophageal adenocarcinoma.</P><P>Gastroesophageal adenocarcinoma (GEA) is a lethal disease where targeted therapies, even when guided by genomic biomarkers, have had limited efficacy. A potential reason for the failure of such therapies is that genomic profiling results could commonly differ between the primary and metastatic tumors. To evaluate genomic heterogeneity, we sequenced paired primary GEA and synchronous metastatic lesions across multiple cohorts, finding extensive differences in genomic alterations, including discrepancies in potentially clinically relevant alterations. Multiregion sequencing showed significant discrepancy within the primary tumor (PT) and between the PT and disseminated disease, with oncogene amplification profiles commonly discordant. In addition, a pilot analysis of cell-free DNA (cfDNA) sequencing demonstrated the feasibility of detecting genomic amplifications not detected in PT sampling. Lastly, we profiled paired primary tumors, metastatic tumors, and cfDNA from patients enrolled in the personalized antibodies for GEA (PANGEA) trial of targeted therapies in GEA and found that genomic biomarkers were recurrently discrepant between the PT and untreated metastases. Divergent primary and metastatic tissue profiling led to treatment reassignment in 32% (9/28) of patients. In discordant primary and metastatic lesions, we found 87.5% concordance for targetable alterations in metastatic tissue and cfDNA, suggesting the potential for cfDNA profiling to enhance selection of therapy.</P><P><B>Significance:</B> We demonstrate frequent baseline heterogeneity in targetable genomic alterations in GEA, indicating that current tissue sampling practices for biomarker testing do not effectively guide precision medicine in this disease and that routine profiling of metastatic lesions and/or cfDNA should be systematically evaluated. <I>Cancer Discov; 8(1); 37–48. ©2017 AACR.</I></P><P><I>See related commentary by Sundar and Tan, p. 14</I>.</P><P><I>See related article by Janjigian et al., p. 49</I>.</P><P><I>This article is highlighted in the In This Issue feature, p. 1</I></P>
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