Electrospray ionization mass spectrometry: from cluster ions to toxic metal ions in biology

In Chapter 1, electrospray ionization mass spectrometry (ESI-MS) was used to examine clusters of protonated amine salt solutions with chloride counter ions in the negative ion mode. These ions have the general formula [(RNH3)xClx+1]-. Primary amines generate a wide cluster distribution with clusters up to 14 mers for methylamine hydrochloride clusters. Secondary and quaternary amines only generate the monomer ion under identical conditions. Collision induced dissociation (CID) of the cluster ions generates cluster ions of lower m/z with the next lower cluster being the most abundant. The product ions from MeNH3Cl 2-, Me2NH2Cl2 - and (MeNH3)2Cl3- have low threshold appearance energies of 1.24 to 2.22 eV center-of-mass frame. Secondary amine monomer ions have lower threshold CID energies than primary amine monomer ions. The amine threshold CID energy decreases as the carbon chain length increases. As an electrospray solvent, isopropyl alcohol (IPA) promotes the formation of counter ions and clustering.;In Chapter 2, salt cluster ions of alkali metal sulfates Mx(SO 4)yz- (M = Li, Na, and Cs) were studied by ESI-MS. Ions with charges up to z = -7, i.e., Na131(SO 4)697- were present in the mass spectra. The effects of capillary temperature, capillary voltage, tube lens voltage, fragmentor voltage, and various solvents were investigated. Collision induced dissociation of the clusters showed that there was an overlap of singly and multiply charged ions at the same m/z. Two different types of instrument interfaces, heated capillary and fragmentor, were utilized in this study. The different cations produced different cluster distributions with lithium sulfate clusters generating the most multiply charged cluster ions. The capillary voltage altered the cluster ion intensity and distribution more than any other parameter on the instrument with the heated capillary interface. The fragmentor voltage produced the largest variation in the cluster ion distribution. Overall, the heated capillary interface produced smaller changes to the cluster ion distribution than the fragmentor interface.;In Chapter 3, solutions comprising two metal chloride compounds were analyzed in negative ion mode by ESI-MS. Various metal clusters, MxCl z- (M = Ce3+, Co2+, Zn 2+ or Ho3+) or CexMyClz - (M = Co2+, Zn2+, or Ho 3+) were present in the mass spectra. No multiply charged ions were observed. Lower heated capillary temperatures favored mixed metal cluster ions. The abundances of the mixed metal clusters increased when a 50/50 isopropyl alcohol/water solution was used compared to a 96/4 isopropyl/water solution. Collision induced dissociation of cerium/cobalt mixed metal clusters revealed that the Co2+ ion generally leaves as part of a neutral fragment, and the negatively charged fragment retains the Ce3+ ion.;In Chapter 4, ESI-MS was used to evaluate toxic metal binding to the [Gln11]-amyloid beta-protein fragment (1-16). Cd and Pb bound to the amyloid fragment; Hg did so weakly. Collision induced dissociation (CID) studies found that Pb and Cd attached to the same binding site as the essential element Zn. Competition studies found that Pb and Cd have a higher affinity for the binding site than Zn. The signal ratio (Cd + peptide)/(Zn + peptide) was 1.39, and the ratio (Pb + peptide)/(Zn + peptide) was 1.85. Cadmium and lead displaced about 80 percent of the bound Zn ions, but an excess of Zn did not remove the bound toxic metals

Evidence for Type Ia Supernova Diversity from Ultraviolet Observations with the Hubble Space Telescope

We present ultraviolet (UV) spectroscopy and photometry of four Type Ia supernovae (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the UV prism of the Advanced Camera for Surveys on the Hubble Space Telescope. This dataset provides unique spectral time series down to 2000 Angstrom. Significant diversity is seen in the near maximum-light spectra (~ 2000--3500 Angstrom) for this small sample. The corresponding photometric data, together with archival data from Swift Ultraviolet/Optical Telescope observations, provide further evidence of increased dispersion in the UV emission with respect to the optical. The peak luminosities measured in uvw1/F250W are found to correlate with the B-band light-curve shape parameter dm15(B), but with much larger scatter relative to the correlation in the broad-band B band (e.g., ~0.4 mag versus ~0.2 mag for those with 0.8 < dm15 < 1.7 mag). SN 2004dt is found as an outlier of this correlation (at > 3 sigma), being brighter than normal SNe Ia such as SN 2005cf by ~0.9 mag and ~2.0 mag in the uvw1/F250W and uvm2/F220W filters, respectively. We show that different progenitor metallicity or line-expansion velocities alone cannot explain such a large discrepancy. Viewing-angle effects, such as due to an asymmetric explosion, may have a significant influence on the flux emitted in the UV region. Detailed modeling is needed to disentangle and quantify the above effects.Comment: 17 pages, 13 figures, accepted by Ap

LONG-TERM DEMONSTRATION OF SORBENT ENHANCEMENT ADDITIVE TECHNOLOGY FOR MERCURY CONTROL

Long-term demonstration tests of advanced sorbent enhancement additive (SEA) technologies have been completed at five coal-fired power plants. The targeted removal rate was 90% from baseline conditions at all five stations. The plants included Hawthorn Unit 5, Mill Creek Unit 4, San Miguel Unit 1, Centralia Unit 2, and Hoot Lake Unit 2. The materials tested included powdered activated carbon, treated carbon, scrubber additives, and SEAs. In only one case (San Miguel) was >90% removal not attainable. The reemission of mercury from the scrubber at this facility prevented >90% capture

LONG-TERM DEMONSTRATION OF SORBENT ENHANCEMENT ADDITIVE TECHNOLOGY FOR MERCURY CONTROL

Long-term demonstration tests of advanced sorbent enhancement additive (SEA) technologies have been completed at five coal-fired power plants. The targeted removal rate was 90% from baseline conditions at all five stations. The plants included Hawthorn Unit 5, Mill Creek Unit 4, San Miguel Unit 1, Centralia Unit 2, and Hoot Lake Unit 2. The materials tested included powdered activated carbon, treated carbon, scrubber additives, and SEAs. In only one case (San Miguel) was >90% removal not attainable. The reemission of mercury from the scrubber at this facility prevented >90% capture

Ecosystem impacts by the Ancestral Puebloans of Chaco Canyon, New Mexico, USA

The Ancestral Puebloans occupied Chaco Canyon, in what is now the southwestern USA, for more than a millennium and harvested useful timber and fuel from the trees of distant forests as well as local woodlands, especially juniper and pinyon pine. These pinyon juniper woodland products were an essential part of the resource base from Late Archaic times (3000-100 BC) to the Bonito phase (AD 800-1140) during the great florescence of Chacoan culture. During this vast expanse of time, the availability of portions of the woodland declined. We posit, based on pollen and macrobotanical remains, that the Chaco Canyon woodlands were substantially impacted during Late Archaic to Basketmaker II times (100 BC-AD 500) when agriculture became a major means of food production and the manufacture of pottery was introduced into the canyon. By the time of the Bonito phase, the local woodlands, especially the juniper component, had been decimated by centuries of continuous extraction of a slow-growing resource. The destabilizing impact resulting from recurrent woodland harvesting likely contributed to the environmental unpredictability and difficulty in procuring essential resources suffered by the Ancestral Puebloans prior to their ultimate departure from Chaco Canyon

Water uncertainty, ritual predictability and agricultural canals at Chaco Canyon, New Mexico

The Pueblo population of Chaco Canyon during the Bonito Phase (AD 800–1130) employed agricultural strategies and water-management systems to enhance food cultivation in this unpredictable environment. Scepticism concerning the timing and effectiveness of this system, however, remains common. Using optically stimulated luminescence dating of sediments and LiDAR imaging, the authors located Bonito Phase canal features at the far west end of the canyon. Additional ED-XRF and strontium isotope (87Sr/86Sr) analyses confirm the diversion of waters from multiple sources during Chaco’s occupation. The extent of this water-management system raises new questions about social organisation and the role of ritual in facilitating responses to environmental unpredictability

Soil analysis in discussions of agricultural feasibility for ancient civilizations: A critical review and reanalysis of the data and debate from Chaco Canyon, New Mexico

<div><p>Questions about how archaeological populations obtained basic food supplies are often difficult to answer. The application of specialist techniques from non-archaeological fields typically expands our knowledge base, but can be detrimental to cultural interpretations if employed incorrectly, resulting in problematic datasets and erroneous conclusions not easily caught by the recipient archaeological community. One area where this problem has failed to find resolution is Chaco Canyon, New Mexico, the center of one of the New World’s most vibrant ancient civilizations. Discussions of agricultural feasibility and its impact on local population levels at Chaco Canyon have been heavily influenced by studies of soil salinity. A number of researchers have argued that salinized soils severely limited local agricultural production, instead suggesting food was imported from distant sources, specifically the Chuska Mountains. A careful reassessment of existing salinity data as measured by electrical conductivity reveals critical errors in data conversion and presentation that have misrepresented the character of the area’s soil and its potential impact on crops. We combine all available electrical conductivity data, including our own, and apply multiple established conversion methods in order to estimate soil salinity values and evaluate their relationship to agricultural productivity potential. Our results show that Chacoan soils display the same salinity ranges and spatial variability as soils in other documented, productive fields in semi-arid areas. Additionally, the proposed large-scale importation of food from the Chuska Mountains region has serious social implications that have not been thoroughly explored. We consider these factors and conclude that the high cost and extreme inflexibility of such a system, in combination with material evidence for local agriculture within Chaco Canyon, make this scenario highly unlikely. Both the soil salinity and archaeological data suggest that there is no justification for precluding the practice of local agriculture within Chaco Canyon.</p></div

General location of Chaco Canyon Cultural Historical Park in relation to the Chuska Mountains.

<p>Four Corners is in upper left corner of figure at intersection of black state lines. Only selected major drainages contributing to or near Chaco Wash are represented. Black triangles are the three closest pedons to Chaco Canyon that have been sampled by the USDA.</p

This table shows estimated crop yield declines at particular soil or irrigation water conductivities.

<p>EC_e is a measurement on the extract from a saturated soil paste. EC_w is the conductivity of irrigation water with yield declines based on an estimated 15–20% leaching fraction. These data are always presented as guidelines, not definitive limits, and are for modern crop varieties. Given the range of tolerance within a given crop type, see squashes, it is possible that varieties used by Chacoan farmers were less susceptible than modern varieties largely grown in wetter climates. Data, except for sunflower, is from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0198290#pone.0198290.ref081" target="_blank">81</a>]. Amaranthus, found to be part of diets at Salmon Ruin and Antelope House, is considered a tolerant plant to salinity [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0198290#pone.0198290.ref082" target="_blank">82</a>]. Chenopodium, Amaranthus, and Asteraceae were found to be significant diet contributions [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0198290#pone.0198290.ref082" target="_blank">82</a>], and each is considered a halophytic, or salt adapted, plant.</p