Modeling mercury in power plant plumes

Measurements of speciated mercury (Hg) downwind of coal-fired power plants suggest that the Hg(II)/(Hg0 + HgII) ratio (where HgII is divalent gaseous Hg and Hg0 is elemental Hg) decreases significantly between the point of emission and the downwind ground-level measurement site, but that the SO2/(Hg0 + HgII) ratio is conserved. We simulated nine power plant plume events with the Reactive & Optics Model of Emissions (ROME), a reactive plume model that includes a comprehensive treatment of plume dispersion, transformation, and deposition. The model simulations fail to reproduce such a depletion in HgII. A sensitivity study of the impact of the HgII dry deposition velocity shows that a difference in dry deposition alone cannot explain the disparity. Similarly, a sensitivity study of the impact of cloud chemistry on results shows that the effect of clouds on Hg chemistry has only minimal impact. Possible explanations include HgII reduction to Hg0 in the plume, rapid reduction of HgII to Hg0 on ground surfaces, and/or an overestimation of the HgII fraction in the power plant emissions. We propose that a chemical reaction not included in current models of atmospheric mercury reduces HgII to Hg0 in coal-fired power plant plumes. The incorporation of two possible reduction pathways for HgII (pseudo-first-order decay and reaction with SO2) shows better agreement between the model simulations and the ambient measurements. These potential HgII to Hg0 reactions need to be studied in the laboratory to investigate this hypothesis. Because the speciation of Hg has a significant effect on Hg deposition, models of the fate and transport of atmospheric Hg may need to be modified to account for the reduction of HgII in coal-fired power plant plumes if such a reaction is confirmed in further experimental investigations.     

Terrain-derived measures for basin conservation and restoration planning

Centuries of human development have altered the connectivity of rivers, adversely impacting ecosystems and the services they provide. Significant investments in natural resource projects are made annually with the goal of restoring function to degraded rivers and floodplains and protecting freshwater resources. Yet restoration projects often fall short of their objectives, in part due to the lack of systems-based strategic planning. To evaluate channel-floodplain (dis)connectivity and erosion/incision hazard at the basin scale, we calculate Specific Stream Power (SSP), an estimate of the energy of a river, using a topographically based, low-complexity hydraulic model. Other basin-wide SSP modeling approaches neglect reach-specific geometric information embedded in Digital Elevation Models. Our approach leverages this information to generate reach-specific SSP-flow curves. We extract measures from these curves that describe (dis)connected floodwater storage capacity and erosion hazard at individual design storm flood stages and demonstrate how these measures may be used to identify watershed-scale patterns in connectivity. We show proof-of-concept using 25 reaches in the Mad River watershed in central Vermont and demonstrate that the SSP results have acceptable agreement with a well-calibrated process-based model (2D Hydraulic Engineering Center's River Analysis System) across a broad range of design events. While systems-based planning of regional restoration and conservation activities has been limited, largely due to computational and human resource requirements, measures derived from low-complexity models can provide an overview of reach-scale conditions at the regional level and aid planners in identifying areas for further restoration and/or conservation assessments.     

Functional Nanomaterials for the Diagnosis of Alzheimer's Disease: Recent Progress and Future Perspectives

Alzheimer's disease (AD) is one of the main causes of dementia worldwide, whereby neuronal death or malfunction leads to cognitive impairment in the elderly population. AD is highly prevalent, with increased projections over the next few decades. Yet current diagnostic methods for AD occur only after the presentation of clinical symptoms. Evidence in the literature points to potential mechanisms of AD induction beginning before clinical symptoms start to present, such as the formation of amyloid beta (Aβ) extracellular plaques and neurofibrillary tangles (NFTs). Biomarkers of AD, including Aβ₄₀, Aβ₄₂, and tau protein, amongst others, show promise for early AD diagnosis. Additional progress is made in the application of biosensing modalities to measure and detect significant changes in these AD biomarkers within patient samples, such as cerebral spinal fluid (CSF) and blood, serum, or plasma. Herein, a comprehensive review of the emerging nano-biomaterial approaches to develop biosensors for AD biomarkers’ detection is provided. Advances, challenges, and potential of electrochemical, optical, and colorimetric biosensors, focusing on nanoparticle-based (metallic, magnetic, quantum dots) and nanostructure-based biomaterials are discussed. Finally, the criteria for incorporating these emerging nano-biomaterials in clinical settings are presented and assessed, as they hold great potential for enhancing early-onset AD diagnostics.     

Mithplatins: Mithramycin SA-Pt(II) Complex Conjugates for the Treatment of Platinum-Resistant Ovarian Cancers

DNA coordinating platinum (Pt) containing compounds cisplatin and carboplatin have been used for the treatment of ovarian cancer therapy for four decades. However, recurrent Pt-resistant cancers are a major cause of mortality. To combat Pt-resistant ovarian cancers, we designed and synthesized a conjugate of an anticancer drug mithramycin with a reactive Pt(II) bearing moiety, which we termed mithplatin. The conjugates displayed both the Mg²⁺-dependent noncovalent DNA binding characteristic of mithramycin and the covalent crosslinking to DNA of the Pt. The conjugate was three times as potent as cisplatin against ovarian cancer cells. The DNA lesions caused by the conjugate led to the generation of DNA double-strand breaks, as also observed with cisplatin. Nevertheless, the conjugate was highly active against both Pt-sensitive and Pt-resistant ovarian cancer cells. This study paves the way to developing mithplatins to combat Pt-resistant ovarian cancers.     

Galacturonsäurederivate. I. Galacturonate aus Acetyl- und Isopropyliden-D-galactopyranosen

Galacturonic Acid Derivatives. I. Galacturonates from Acetyl- and Isopropylidene-D-galactopyranoses Galacturonic acid derivatives to be employed as glycosyl donors in saccharide synthesis are prepared from galacturonic acid itself or from galactose. Various syntheses of 1,2,3,4-tetra-O-acetyl-D-galactopyranuronic acids ( 6 ) with differently protected carboxyl group and attempts of their conversion into galacturonpyranosyl bromides are described. The starting materials were 1,2;3,4-di-O-isopropylidene-α-D-galactopyranose and acetylated galactopyranose derivatives, respectively.     

Synthesen von C-Nucleosiden und C-Nucleosidanaloga. IV. Darstellung und Charakterisierung von 5(S)-bzw. 5(R)-Tetrahydroxybutyl-3-methyl-1,3-oxazolidinen

Syntheses of C-Nucleosides and Analogs of C-Nucleosides. IV. Preparation and Characterization of 5(S)- and 5(R)-Tetrahydroxybutyl-3-methyl-1,3-oxazolidines 1-Deoxy-1-methylamino-D-hexitols 1,2,3 react with ketendithioacetals 4 to give the acyclic C-nucleosides 5,6 and 7 . The structure of the compounds were verified by means of periodate oxidation and spectroscopic investigations. Some properties of the acyclic C-nucleosides were investigated by acetalation reactions on the tetrahydroxybutyl chain.     

Synthese und Reaktionen von 2-[Bis-(alkylthio)-methyliden]-indan-1,3-dionen

Synthesis and Reactions of 2-[Bis-(alkylthio)-methyliden]-indan-1,3-diones The 2-[bis-(alkylthio)-methyliden]-indan-1,3-diones 3 and especially the methyl-compound 3a react with nucleophiles by substitution of the CH₃ S group. The reaction with amines are yields the S,N or N,N-acetales 7 and 8 , respectively. Diamines, amino hydroxy- or amino-mercapto compounds as dinucleophiles give the cyclic compounds 9 or the condensed heterocycles 12 and 16 , where the carbonyl group has been integrated in the cyclisation. Also carbanions react with 3a under substitution. The structures of the final products are determined with ir-, ¹H-n.m.r.- and ms-spectra.