Chemistry Commons^™

Upper Tropospheric Water Vapour Variability At High Latitudes- Part 1: Influence Of The Annular Modes, Christopher E. Sioris, Jason Zou, David A. Plummer, Chris D. Boone, C. Thomas Mcelroy, Patrick E. Sheese, Omid Moeini, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

Seasonal and monthly zonal medians of water vapour in the upper troposphere and lower stratosphere (UTLS) are calculated for both Atmospheric Chemistry Experiment (ACE) instruments for the northern and southern high-latitude regions (60-90° N and 60-90°S). Chosen for the purpose of observing high-latitude processes, the ACE orbit provides sampling of both regions in 8 of 12 months of the year, with coverage in all seasons. The ACE water vapour sensors, namely MAESTRO (Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) and the Fourier Transform Spectrometer (ACE-FTS) are currently the only satellite instruments that can probe from …

Mipas Imk/Iaa Cfc-11 (Ccl3f) And Cfc-12 (Ccl2f2) Measurements: Accuracy, Precision And Long-Term Stability, E. Eckert, A. Laeng, S. Lossow, S. Kellmann, G. Stiller, T. Von Clarmann, N. Glatthor, M. Hopfner, M. Kiefer, H. Oelhaf, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Profiles of CFC-11 (CCl₃F) and CFC-12 (CCl₂F₂) of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the European satellite Envisat have been retrieved from versions MIPAS/4.61 to MI-PAS/4.62 and MIPAS/5.02 to MIPAS/5.06 level-1b data using the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research (IMK) and Consejo Superior de Investigaciones Cientificas (CSIC), Instituto de Astrofisica de Andalucia (IAA). These profiles have been compared to measurements taken by the balloon-borne cryosampler, Mark IV (MkIV) and MIPAS-Balloon (MIPAS-B), the airborne MIPAS-STRatospheric aircraft (MIPAS-STR), the satellite-borne Atmospheric Chemistry …

Validation Of The Global Distribution Of Co2 Volume Mixing Ratio In The Mesosphere And Lower Thermosphere From Saber, L. Rezac, Y. Jian, J. Yue, J. M. Russell Iii, A. Kutepov, R. Garcia, K. Walker, P. Bernath

Chemistry & Biochemistry Faculty Publications

The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite has been measuring the limb radiance in 10 broadband infrared channels over the altitude range from ~ 400 km to the Earth's surface since 2002. The kinetic temperatures and CO₂ volume mixing ratios (VMRs) in the mesosphere and lower thermosphere have been simultaneously retrieved using SABER limb radiances at 15 and 4.3 μm under nonlocal thermodynamic equilibrium (non-LTE) conditions. This paper presents results of a validation study of the SABER CO₂ VMRs obtained with a two-channel, self-consistent …

Simulation Of Energetic Particle Precipitation Effects During The 2003-2004 Arctic Winter, C. E. Randall, V. L. Harvey, L. A. Holt, D. R. Marsh, D. Kinnison, B. Funke, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Energetic particle precipitation (EPP) during the 2003-2004 Arctic winter led to the production and subsequent transport of reactive odd nitrogen (NO_x=NO+NO₂) from the mesosphere and lower thermosphere (MLT) into the stratosphere. This caused NO_x enhancements in the polar upper stratosphere in April 2004 that were unprecedented in the satellite record. Simulations of the 2003-2004 Arctic winter with the Whole Atmosphere Community Climate Model using Specified Dynamics (SD-WACCM) are compared to satellite measurements to assess our understanding of the observed NO_x enhancements. The comparisons show that SD-WACCM clearly displays the descent of NO_x produced …

Growth In Stratospheric Chlorine From Short-Lived Chemicals Not Controlled By The Montreal Protocol, R. Hossaoni, M. P. Chipperfield, A. Saiz-Lopez, J. J. Harrison, R. Von Glasow, R. Sommariva, E. Atlas, M. Navarro, S. A. Montzka, W. Feng, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

We have developed a chemical mechanism describing the tropospheric degradation of chlorine containing very short-lived substances (VSLS). The scheme was included in a global atmospheric model and used to quantify the stratospheric injection of chlorine from anthropogenic VSLS (Cl_y^VSLS) between 2005 and 2013. By constraining the model with surface measurements of chloroform (CHCl₃), dichloromethane (CH₂Cl₂), tetrachloroethene (C₂Cl₄), trichloroethene (C₂HCl₃), and 1,2-dichloroethane (CH₂ClCH₂Cl), we infer a 2013 Cl_y^VSLS mixing ratio of 123 parts per trillion (ppt). Stratospheric injection …

Whole Genome Comparison Of A Large Collection Of Mycobacteriophages Reveals A Continuum Of Phage Genetic Diversity, Welkin H. Pope, Charles A. Bowman, Daniel A. Russell, Deborah Jacobs-Sera, David J. Asai, Steven G. Cresawn, William R. Jacobs Jr, Roger W. Hendrix, Jeffrey G. Lawrence, Graham F. Hatfull, Dr. Kathleen Cornely

Chemistry & Biochemistry Faculty Publications

The bacteriophage population is large, dynamic, ancient, and genetically diverse. Limited genomic information shows that phage genomes are mosaic, and the genetic architecture of phage populations remains ill-defined. To understand the population structure of phages infecting a single host strain, we isolated, sequenced, and compared 627 phages of Mycobacterium smegmatis. Their genetic diversity is considerable, and there are 28 distinct genomic types (clusters) with related nucleotide sequences. However, amino acid sequence comparisons show pervasive genomic mosaicism, and quantification of inter-cluster and intra-cluster relatedness reveals a continuum of genetic diversity, albeit with uneven representation of different phages. Furthermore, rarefaction analysis shows …

Comparative Genomics Of Cluster O Mycobacteriophages, Steven G. Cresawn, Welkin H. Pope, Deborah Jacobs-Sera, Charles A. Bowman, Daniel A. Russell, Rebekah M. Dedrick, Tamarah Adair, Kirk R. Anders, Sarah Ball, David Bollivar, Caroline Breitenberger, Sandra H. Burnett, Kristen Butela, Deanna Byrnes, Sarah Carzo, Dr. Kathleen Cornely, Trevor Cross, Richard L. Daniels, David Dunbar, Ann M. Findley, Chris R. Gissendanner, Urszula P. Golebiewska, Grant A. Hartzog, J. Robert Hatherill, Lee E. Hughes, Chernoh S. Jalloh, Carla De Los Santos, Kevin Ekanem, Sphindile L. Khambule, Rodney A. King, Christina King-Smith, Karen Klyczek, Greg P. Krukonis, Christian Laing, Jonathan S. Lapin, A. Javier Lopez, Sipho M. Mkhwanazi, Sally D. Molloy, Deborah Moran, Vanisha Munsamy, Eddie Pacey, Ruth Plymale, Marianne Poxleitner, Nathan Reyna, Joel F. Schildbach, Joseph Stukey, Sarah E. Taylor, Vassie C. Ware, Amanda L. Wellmann, Daniel Westholm, Donna Wodarski, Michelle Zajko, Thabiso S. Zikalala, Roger W. Hendrix, Graham F. Hatfull

Chemistry & Biochemistry Faculty Publications

Mycobacteriophages – viruses of mycobacterial hosts – are genetically diverse but morphologically are all classified in the Caudovirales with double-stranded DNA and tails. We describe here a group of five closely related mycobacteriophages – Corndog, Catdawg, Dylan, Firecracker, and YungJamal – designated as Cluster O with long flexible tails but with unusual prolate capsids. Proteomic analysis of phage Corndog particles, Catdawg particles, and Corndog-infected cells confirms expression of half of the predicted gene products and indicates a non-canonical mechanism for translation of the Corndog tape measure protein. Bioinformatic analysis identifies 8–9 strongly predicted SigA promoters and all five Cluster O …

Simultaneous Analysis Of The Ballik-Ramsay And Phillips Systems Of C2 And Observation Of Forbidden Transitions Between Singlet And Triplet States, Wang Chen, Kentarou Kawaguchi, Peter F. Bernath, Jian Tang

Chemistry & Biochemistry Faculty Publications

6229 lines of the Ballik-Ramsay system (b₃Σ_g^--a₃Π_u) and the Phillips system (A¹Π_u-X¹Σ_g⁺) of C₂ up to v = 8 and J = 76, which were taken from the literature or assigned in the present work, were analyzed simultaneously by least-squares fitting with 82 Dunham-like molecular parameters and spin-orbit interaction constants between the b₃Σ_g^- and X¹Σ_g⁺ states with a standard deviation of 0.0037 cm^-1 for the whole data set. As a …

Effect Of Methoxy Substituents On The Activation Barriers Of The Glutathione Peroxidase-Like Mechanism Of An Aromatic Cyclic Seleninate, Craig A. Bayse, Ashley L. Shoaf

Chemistry & Biochemistry Faculty Publications

Density functional theory (DFT) models including explicit water molecules have been used to model the redox scavenging mechanism of aromatic cyclic seleninates. Experimental studies have shown that methoxy substitutions affect the rate of scavenging of reactive oxygen species differently depending upon the position. Activities are enhanced in the para position, unaffected in the meta, and decreased in the ortho. DFT calculations show that the activation barrier for the oxidation of the selenenyl sulfide, a proposed key intermediate, is higher for the ortho methoxy derivative than for other positions, consistent with the low experimental conversion rate.

Spectroscopic Characterization Of Oceanic Dissolved Organic Matter Isolated By Reverse Osmosis Coupled With Electrodialysis, John R. Helms, Jingdong Mao, Hongmei Chen, E. Michael Perdue, Nelson W. Green, Patrick G. Hatcher, Kenneth Mopper, Aron Stubbins

Chemistry & Biochemistry Faculty Publications

Oceanic dissolved organic matter (DOM) is one of the largest pools of reduced carbon on Earth, yet DOM remains poorly chemically characterized. Studies to determine the chemical nature of oceanic DOM have been impeded by the lack of efficient and non-fractioning methods to recover oceanic DOM. Here, a DOM fraction (~40 to 86% recovery) was isolated using reverse osmosis/electrodialysis (RO/ED) and analyzed by solid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy. Samples were obtained from biogeochemically distinct environments: photobleached surface gyre, productive coastal upwelling zone, oxygen minimum, North Atlantic Deep Water, and North Pacific Deep Water. A ubiquitous ‘background’ refractory …

Characterization And Photodegradation Of Dissolved Organic Matter (Dom) From A Tropical Lake And Its Dominant Primary Producer, The Cyanobacteria Microcystis Aeruginosa, Thais B. Bittar, Aron Stubbins, Armando A. H. Vieira, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

This study investigates optical and high-resolution molecular signatures and photochemical degradation of DOM from the Barra Bonita Reservoir (BB-DOM), a tropical eutrophic lake, as well as from its dominant phytoplankton species, the cyanobacteria Microcystis aeruginosa (Microcystis-DOM). Consistent with a predominantly autotrophic source, BB-DOM and Microcystis-DOM exhibited high protein-like fluorescence and contained a large number of aliphatics. Microcystis-DOM was enriched in peptide-like formulae, while BB-DOM had higher chromophoric and fluorescent DOM(CDOM and FDOM) and was enriched in moderately unsaturated formulae, indicating additions of terrigenous DOM and/or in situ processing of autochthonous material in the lake. Consistent with …

Interesting Properties Of P-, D-, And F-Block Elements When Coordinated With Dipicolinic Acid And Its Derivatives As Ligands: Their Use As Inorganic Pharmaceuticals, Michael J. Celestine, Jimmie L. Bullock, Shivani Boodram, Varma H. Rambaran, Alvin A. Holder

Chemistry & Biochemistry Faculty Publications

This is a review of the literature concerning the interesting properties of p-, d-, and f-block elements when coordinated with 2,6-pyridinedicarboxylic acid (dipicolinic acid, H₂dipic) and its derivatives as ligands, with a focus on their use as inorganic pharmaceuticals. Some of the complexes reported were used as insulin-like, bioimaging contrasting agents, antimicrobial agents, and anticancer agents.

Note: Improved Line Strengths Of Rovibrational And Rotational Transitions Within The X3Σ⁻ Ground State Of Nh, James S.A. Brooke, Peter F. Bernath, Colin M. Western

Chemistry & Biochemistry Faculty Publications

Recently, a line list including positions and transition strengths was published for the NH X³Σ⁻ rovibrational and rotational transitions. The calculation of the transition strengths requires a conversion of transition matrix elements from Hund’s case (b) to (a). The method of this conversion has recently been improved during other work on the OH X²Π rovibrational transitions, by removing an approximation that was present previously. The adjusted method has been applied to the NH line list, resulting in more accurate transition strengths. An updated line list is presented that contains all possible transitions with v′ and …

Proton-Electrostatic Localization: Explaining The Bioenergetic Conundrum In Alkalophilic Bacteria, James Weifu Lee

Chemistry & Biochemistry Faculty Publications

The decades-longstanding energetic conundrum of alkalophilic bacteria as to how they are able to synthesize ATP has now, for the first time, been clearly solved using the proton-electrostatics localization hypothesis. This is a major breakthrough advance in understanding proton-coupling bioenergetics over the Nobel-prize work of Peter Mitchell’s chemiosmotic theory. The widespread textbook Mitchellian proton motive force (pmf) equation has now been significantly revised. Use of the newly derived equation results in an overall pmf value (215~233 mV) that is more than 4 times larger than that (44.3 mV) calculated from the Mitchellian equation for the alkalophilic bacteria growing at pH …

Peptide Inhibitor Of Complement C1 (Pic1) Rapidly Inhibits Complement Activation After Intravascular Injection In Rats, Julia A. Sharp, Pamela S. Hair, Haree K. Pallera, Parvathi S. Kumar, Clifford T. Mauriello, Julius O. Nyalwidhe, Cody A. Phelps, Dalnam Park, Nicole M. Thielens, Stephen M. Pascal, Waldon Chen, Diane M. Duffy, Frank A. Lattanzio, Kenji M. Cunnion, Neel K. Krishna

Chemistry & Biochemistry Faculty Publications

The complement system has been increasingly recognized to play a pivotal role in a variety of inflammatory and autoimmune diseases. Consequently, therapeutic modulators of the classical, lectin and alternative pathways of the complement system are currently in preclinical and clinical development. Our laboratory has identified a peptide that specifically inhibits the classical and lectin pathways of complement and is referred to as Peptide Inhibitor of Complement C1 (PIC1). In this study, we determined that the lead PIC1 variant demonstrates a salt-dependent binding to C1q, the initiator molecule of the classical pathway. Additionally, this peptide bound to the lectin pathway initiator …

Experimental Demonstration Of Localized Excess Protons At A Water-Membrane Interface, Haitham A. Saeed, James W. Lee

Chemistry & Biochemistry Faculty Publications

The widespread Mitchellian proton motive force equation has recently been revised with the proton-electrostatics localization hypothesis, which, for the first time, successfully elucidates the 30-year longstanding energetic conundrum of ATP synthesis in alkalophilic bacteria. To demonstrate the fundamental behavior of localized protons in a pure water-membrane-water system in relation to the newly derived pmf equation, excess protons and excess hydroxyl anions were generated by utilizing an "open-circuit" water-electrolysis system and their distributions were tested using a proton-sensing aluminum membrane. The proton-sensing film placed at the membrane-water interface displayed dramatic localized proton activity while that placed into the bulk water phase …

Plant Species Rather Than Climate Greatly Alters The Temporal Pattern Of Litter Chemical Composition During Long-Term Decomposition, Yongfu Li, Na Chen, Mark E. Harmon, Yuan Li, Xiaoyan Cao, Mark A. Chappell, Jingdong Mao

Chemistry & Biochemistry Faculty Publications

A feedback between decomposition and litter chemical composition occurs with decomposition altering composition that in turn influences the decomposition rate. Elucidating the temporal pattern of chemical composition is vital to understand this feedback, but the effects of plant species and climate on chemical changes remain poorly understood, especially over multiple years. In a 10-year decomposition experiment with litter of four species (Acer saccharum, Drypetes glauca, Pinus resinosa, and Thuja plicata) from four sites that range from the arctic to tropics, we determined the abundance of 11 litter chemical constituents that were grouped into waxes, carbohydrates, …

Relative Drifts And Biases Between Six Ozone Limb Satellite Measurements From The Last Decade, N. Rahpoe, M. Weber, A. V. Rozanov, K. Weigel, H. Bovensmann, J. P. Burrows, A. Laeng, G. Stiller, T. Von Clarmann, E. Kyrölä, V. F. Sofieva, J. Tamminen, K. Walker, D. Degenstein, A. E. Bourassa, R. Hargreaves, P. Bernath, J. Urban, D. P. Murtagh

Chemistry & Biochemistry Faculty Publications

As part of European Space Agency's (ESA) climate change initiative, high vertical resolution ozone profiles from three instruments all aboard ESA's Envisat (GOMOS, MIPAS, SCIAMACHY) and ESA's third party missions (OSIRIS, SMR, ACE-FTS) are to be combined in order to create an essential climate variable data record for the last decade. A prerequisite before combining data is the examination of differences and drifts between the data sets. In this paper, we present a detailed analysis of ozone profile differences based on pairwise collocated measurements, including the evolution of the differences with time. Such a diagnosis is helpful to identify strengths …

Retrieval And Validation Of Carbon Dioxide, Methane, And Water Vapor For The Canary Islands Ir-Laser Occultation Experiment, V. Proschek, G. Kirchengast, S. Schweitzer, J.S. A. Brooke, P. F. Bernath, C. B. Thomas, J. G. Wang, K. A. Tereszchuk, G. González Abad, R. J. Hargreaves, C. A. Beale, J. J. Harrison, P. A. Martin, V. L. Kasyutich, C. Gerbig, O. Kolle, A. Loescher

Chemistry & Biochemistry Faculty Publications

The first ground-based experiment to prove the concept of a novel space-based observation technique for microwave and infrared-laser occultation between low-Earthorbit satellites was performed in the Canary Islands between La Palma and Tenerife. For two nights from 21 to 22 July 2011 the experiment delivered the infrared-laser differential transmission principle for the measurement of greenhouse gases (GHGs) in the free atmosphere. Such global and long-term stable measurements of GHGs, accompanied also by measurements of thermodynamic parameters and line-of-sight wind in a self-calibrating way, have become very important for climate change monitoring. The experiment delivered promising initial data for demonstrating the …

Decrease Of Carbon Tetrachloride (Ccl⁴) Over 2004-2013 As Inferred From Global Occultation Measurements With Ace-Fts, E. Mahieu, Peter F. Bernath, Christopher D. Boone, Kaley A. Walker

Chemistry & Biochemistry Faculty Publications

In this contribution, we use infrared solar occultation measurements performed by the ACE-FTS (Atmospheric Chemistry Experiment – Fourier Transform Spectrometer) instrument onboard the SCISAT-1 Canadian satellite (Bernath et al., 2005). Since its launch in August 2003, this spectrometer has been in continuous operation with no significant degradation of its performance, and global measurements are available from late February 2004 onwards, spanning now more than a decade.

Global Ozone Chemistry And Related Trace Gas Data Records For The Stratosphere (Gozcards): Methodology And Sample Results With A Focus On Hcl, H20, And 03, L. Froidevaux, J. Anderson, H. J. Wang, R. A. Fuller, M. J. Schwartz, M. L. Santee, N. J. Livesey, H. C. Pumphrey, P. F. Bernath, J. M. Russell Iii, M. P. Mccormick

Chemistry & Biochemistry Faculty Publications

We describe the publicly available data from the Global OZone Chemistry And Related trace gas Data records for the Stratosphere (GOZCARDS) project and provide some results, with a focus on hydrogen chloride (HCl), water vapor (H₂O), and ozone (O₃). This data set is a global long-term stratospheric Earth system data record, consisting of monthly zonal mean time series starting as early as 1979. The data records are based on high-quality measurements from several NASA satellite instruments and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on SCISAT. We examine consistency aspects between the various data sets. …

Recent Increase Of Ethane Detected In The Remote Atmosphere Of The Northern Hemisphere, Bruno Franco, Whitney Bader, Benoît Bovy, Emmanuel Mahieu, Emily V. Fischer, Kimberly Strong, Stephanie Conway, James W. Hannigan, Eric Nussbaumer, Peter F. Bernath, Chris D. Boone, Kaley A. Walker

Chemistry & Biochemistry Faculty Publications

Ethane (C₂H₆) has a large impact on tropospheric composition and air quality because of its involvement in the global VOC (volatile organic compound) – HO_x – NO_x chemistry responsible for generating and destroying tropospheric ozone. By acting as a major sink for tropospheric OH radicals, the abundance of C₂H₆ influences the atmospheric content of carbon monoxide and impacts the lifetime of methane. Moreover, it is an important source of PAN, a thermally unstable reservoir for NOx radicals.

On a global scale, the main sources of C₂H₆ are leakage from the production, transport of natural gas loss, biofuel consumption …

Assessment Of Water Vapor Isotopologue Measurements By Ace-Fts And Odin-Smr, Ralf Bauer, Patrick Sheese, Kaley Walker, Joachim Urban, Donal Murtagh, Chris Boone, Peter Bernath, Gloria Manney

Chemistry & Biochemistry Faculty Publications

[Introduction] Knowing the isotopic composition of trace gases can improve our understanding of processes in the Earth's atmosphere causing isotopic fractionation. In many studies, isotopologue (molecules of identical chemical but different isotopic composition) amounts are primarily discussed as δ values, which are defined relative to a standard, e.g.:

Ace-Fts And Haloe Observations Of Hydrogen Fluoride (Hf) And Their Comparison With Slimcat Chemical Transport Model Calculations, Jeremy Harrison, Martyn Chipperfield, Chris Boone, Peter Bernath, Lucien Froidevaux, John Anderson, James Russell Iii

Chemistry & Biochemistry Faculty Publications

The majority of fluorine in the atmosphere has resulted from the anthropogenic emission of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Most tropospheric fluorine is present in its emitted 'organic' form due to the molecules having long lifetimes (up to a decade or longer). Thus they are able to reach the stratosphere where they are broken down, liberating fluorine. The principal degradation products are carbonyl fluoride (COF2), carbonyl chloride fluoride (COClF), and hydrogen fluoride (HF); of these HF is the most abundant. In fact at the top of the stratosphere most of the fluorine is present as HF, which, due …

Use Of Esi-Fticr-Ms To Characterize Dissolved Organic Matter In Headwater Streams Draining Forest-Dominated And Pasture-Dominated Watersheds, Yuehan Lu, Xiaping Li, Rajaa Mesfioui, James E. Bauer, R. M. Chambers, Elizabeth A. Canuel, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) has proven to be a powerful technique revealing complexity and diversity of natural DOM molecules, but its application to DOM analysis in grazing-impacted agricultural systems remains scarce. In the present study, we presented a case study of using ESI-FTICR-MS in analyzing DOM from four headwater streams draining forest-or pasture-dominated watersheds in Virginia, USA. In all samples, most formulas were CHO compounds (71.8-87.9%), with other molecular series (CHOS, CHON, CHONS, and CHOP (N, S)) accounting for only minor fractions. All samples were dominated by molecules falling in the lignin-like region (H/C …

Wavelength Dependent Specific Plasmon Resonance Coupling Of Single Silver Nanoparticles With Egfp, Kerry J. Lee, Tao Huang, Prakash D. Nallathamby

Chemistry & Biochemistry Faculty Publications

Noble metal nanoparticles (NPs) possess unique plasmonic properties, enabling them to serve as sub-diffraction light sources and nano-antennae for a wide range of applications. Here we report the specific interaction of single Ag NPs with single EGFP molecules and a high dependence of their interaction upon localized-surface-plasmon-resonance (LSPR) spectra of single Ag NPs and EGFP. The LSPR spectra of single red Ag NPs show a stunning 60 nm blue-shift during their incubation with EGFP, whereas they remain unchanged during their incubation with bovine serum albumin (BSA). Interestingly, the peak wavelengths of the LSPR spectra of green and blue Ag NPs …

Mass Loss And Chemical Structures Of Wheat And Maize Straws In Response To Ultravoilet-B Radiation And Soil Contact, Guixiang Zhou, Jiabao Zhang, Jingdong Mao, Congzhi Zhang, Lin Chen, Xiuli Xin, Bingzi Zhao

Chemistry & Biochemistry Faculty Publications

The role of photodegradation, an abiotic process, has been largely overlooked during straw decomposition in mesic ecosystems. We investigated the mass loss and chemical structures of straw decomposition in response to elevated UV-B radiation with or without soil contact over a 12-month litterbag experiment. Wheat and maize straw samples with and without soil contact were exposed to three radiation levels: a no-sunlight control, ambient solar UV-B, and artificially elevated UV-B radiation. A block control with soil contact was not included. Compared with the no-sunlight control, UV-B radiation increased the mass loss by 14-19% and the ambient radiation by 9-16% for …

Long-Term Litter Decomposition Controlled By Manganese Redox Cycling, Marco Keiluweit, Peter Nico, Mark E. Harmon, Jingdong Mao, Jennifer Pett-Ridge, Markus Kleber

Chemistry & Biochemistry Faculty Publications

Litter decomposition is a keystone ecosystem process impacting nutrient cycling and productivity, soil properties, and the terrestrial carbon (C) balance, but the factors regulating decomposition rate are still poorly understood. Traditional models assume that the rate is controlled by litter quality, relying on parameters such as lignin content as predictors. However, a strong correlation has been observed between the manganese (Mn) content of litter and decomposition rates across a variety of forest ecosystems. Here, we show that long-term litter decomposition in forest ecosystems is tightly coupled to Mn redox cycling. Over 7 years of litter decomposition, microbial transformation of litter …

Characterization Of Terrestrial Dissolved Organic Matter Fractionated By Ph And Polarity And Their Biological Effects On Plant Growth, Rachel L. Sleighter, Paolo Caricasole, Kristen M. Richards, Terry Hanson, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

Background: Humic substances are ubiquitous in the environment, complex mixtures, and known to be beneficial to plant growth. To better understand and identify components responsible for plant growth stimulation, a terrestrial aquatic DOM sample was fractionated according to pH and polarity, obtaining acid-soluble and acid-insoluble portions, as well as acid-soluble hydrophobic and hydrophilic fractions using C18. The various fractions were characterized then evaluated for their biological effects on plant growth using bioassays with corn at two carbon rates.

Results: Approximately 43% and 57% of the carbon, and 31% and 69% of the iron, was found in the acid-insoluble and acid-soluble …

Comparison Of Upper Tropospheric Carbon Monoxide From Mopitt, Ace-Fts, And Hippo-Qcls, Sara Martínez-Alonzo, Merritt N. Deeter, Helen M. Worden, John C. Gille, Louisa K. Emmons, Laura L. Pan, Mijeong Park, Gloria L. Manney, Peter F. Bernath, Chris D. Boone

Chemistry & Biochemistry Faculty Publications

Products from the Measurements Of Pollution In The Troposphere (MOPITT) instrument are regularly validated using in situ airborne measurements. However, few of these measurements reach into the upper troposphere, thus hindering MOPITT validation in that region. Here we evaluate upper tropospheric (~500 hPa to the tropopause) MOPITT CO profiles by comparing them to satellite Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) retrievals and to measurements from the High-performance Instrumented Airborne Platform for Environmental Research Pole to Pole Observations (HIPPO) Quantum Cascade Laser Spectrometer (QCLS). Direct comparison of colocated v5 MOPITT thermal infrared-only retrievals, v3.0 ACE-FTS retrievals, and HIPPO-QCLS measurements shows …