Quantifying bacteria-contaminant interactions (Bacillus subtilis).

Experiments were conducted to probe for the existence of positive sites on the cell wall of the Gram-positive bacterium Bacillus subtilis through a combination of electrophoretic mobility measurements and anion adsorption experiments with iodide. Iodide adsorption onto Bacillus subtilis was measured as a function of pH, ionic strength, solid:solute ratio, and time. The experimental data were interpreted using a surface complexation approach. The I- adsorption data were best fit with a single surface site reaction, with the iodide ion forming a surface complex with the positively-charged amino functional group located on the bacterial cell wall: R-NH3+ + I- ↔ R-NH3-I- (log K = 8.9 +/- 0.2). Electrophoretic mobility measurements, conducted as a function of pH and electrolyte ionic strength, support the presence of positively-charged surface functionalities at low pH under experimental conditions. Amino-anion stability constants may be incorporated into surface complexation models in order to accurately predict the bioavailability and exposure risk of radioiodine in the environment. Additional anion adsorption experiments in metal-anion-bacteria ternary systems were conducted to determine the effect of multi-valent cations on the electrokinetic properties of the cell wall and its ability to adsorb anions. Adsorption results demonstrated that both anions and (oxy)anions have a pH-dependent affinity for the cell wall of B. subtilis below pH 5. Increased adsorption of anions at higher pH values (\u3epH 4) was observed in the presence of 1 mM Ca. In contrast, no significant little adsorption was observed at similar pH values in the presence of both 0.1 mM and 1 mM La. The presence of positively-charged ions at the bacteria-solute interface can influence the mobility of anionic contaminants and further refines the surface complex approach. Source: Masters Abstracts International, Volume: 42-03, page: 0895. Adviser: David Fowle. Thesis (M.Sc.)--University of Windsor (Canada), 2003

Comparison of Fuel Yield of Biomaterials Between Fast Pyrolysis and Gasification

Pyrolysis is a viable method of extracting combustible fuels as gases or liquids from various, high carbon and hydrogen containing biomaterials. This Meta-study attempts to find the ideal combinations of processes for maximising biofuel output by comparing a range of biomaterials (cotton stalks, algae and peach scraps), put through the two primary methods of pyrolysis, through analysis of reactor type, Temperature, particle size and lower heating value achieved from biofuel output. It is proposed that the fast pyrolysis of Algae in a Fluidized bed reactor at a temperature of 550°C is the optimum combination of parameters for maximising biofuel output in terms of bio-oil yield and lower heating value (LHV) in kJ/kg

Observation of the dynamic Jahn-Teller effect in the excited states of nitrogen-vacancy centers in diamond

The optical transition linewidth and emission polarization of single nitrogen-vacancy (NV) centers are measured from 5 K to room temperature. Inter-excited state population relaxation is shown to broaden the zero-phonon line and both the relaxation and linewidth are found to follow a T^5 dependence for T up to 100 K. This dependence indicates that the dynamic Jahn-Teller effect is the dominant dephasing mechanism for the NV optical transitions at low temperatures

Nuclear Spin Relaxation

Nuclear spin relaxation rates due to magnetic dipole interactions and atomic diffusion in solids are calculated for some two- and three-dimensional systems and for some models of common diffusion mechanisms. NMR magnetic dipolar spectral density functions are obtained for some lattice diffusion models for two-dimensional lattice diffusion on a square lattice and compared with the results for the BPP and continuum diffusion models. Numerical results and analytic approximations are obtained for dipolar interactions between spins diffusing in a plane, and interactions between diffusing spins in a plane with fixed spins in a separate parallel plane. Results for the longitudinal spin relaxation rates in the laboratory and rotating frames are obtained for square lattices and show strong dependence on the direction of the applied magnetic field relative to the crystal axes. A simple matrix expression is derived for the atom jump probabilities due to an interstitial defect moving by an interstitialcy diffusion mechanism. This expression is used to obtain the tracer correlation factor and to calculate the atom jump probabilities numerically for various cubic and two-dimensional systems. An integral expression, involving atom jump probabilities, is obtained for the atomic displacement probabilities due to a single atom-defect encounter

PACE Technical Report Series, Volume 6: Data Product Requirements and Error Budgets Consensus Document

This chapter summarizes ocean color science data product requirements for the Plankton, Aerosol, Cloud,ocean Ecosystem (PACE) mission's Ocean Color Instrument (OCI) and observatory. NASA HQ delivered Level-1 science data product requirements to the PACE Project, which encompass data products to be produced and their associated uncertainties. These products and uncertainties ultimately determine the spectral nature of OCI and the performance requirements assigned to OCI and the observatory. This chapter ultimately serves to provide context for the remainder of this volume, which describes tools developed that allocate these uncertainties into their components, including allowable OCI systematic and random uncertainties, observatory geo location uncertainties, and geophysical model uncertainties

PACE Technical Report Series, Volume 5: Mission Formulation Studies

This chapter summarizes the mission architecture for the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission, ranging from its scientific rationale to the history of its realized conception to itspresent-day organization and management. This volume in the PACE Technical Report series focuses ontrade studies that informed the formulation of the mission in its pre-Phase A (2014-2016; pre-formulation:define a viable and affordable concept) and Phase A (2016-2017; concept and technology development).With that in mind, this chapter serves to introduce the mission by providing: a brief summary of thescience drivers for the mission; a history of the direction of the mission to NASA's Goddard Space Flight Center (GSFC); a synopsis of the mission's and instruments' management and development structures; and a brief description of the primary components and elements that form the foundation ofthe mission, encompassing the major mission segments (space, ground, and science data processing) and their roles in integration, testing, and operations

A Fast Radio Burst in a Compact Galaxy Group at zz~1

FRB 20220610A is a high-redshift Fast Radio Burst (FRB) that has not been observed to repeat. Here, we present rest-frame UV and optical $\textit{Hubble Space Telescope}$ observations of the field of FRB 20220610A. The imaging reveals seven extended sources, one of which we identify as the most likely host galaxy with a spectroscopic redshift of $z$=1.017. We spectroscopically confirm at least three additional sources to be at the same redshift, and identify the system as a compact galaxy group with possible signs of interaction among group members. We determine the host of FRB 20220610A to be a star-forming galaxy with stellar mass of $\approx10^{9.7}\,M_{\odot}$, mass-weighted age of $\approx2.6$~Gyr, and star formation rate (integrated over the last 100 Myr) of $\approx1.7$~M$_{\odot}$~yr$^{-1}$. These host properties are commensurate with the star-forming field galaxy population at z~1 and trace their properties analogously to the population of low-$z$ FRB hosts. Based on estimates of the total stellar mass of the galaxy group, we calculate a fiducial contribution to the observed Dispersion Measure (DM) from the intragroup medium of $\approx 110-220$ $\rm pc \, cm^{-3}$ (rest-frame). This leaves a significant excess of $500^{+272}_{-109}$ $\rm pc \, cm^{-3}$ (in the observer frame), with additional sources of DM possibly originating from the circumburst environment, host galaxy interstellar medium, and/or foreground structures along the line of sight. Given the low occurrence rates of galaxies in compact groups, the discovery of an FRB in such a group demonstrates a rare and novel environment in which FRBs can occur.Comment: 24 pages, 8 figures, 2 tables, submitte

Host Galaxy Properties and Offset Distributions of Fast Radio Bursts: Implications for Their Progenitors

We present observations and detailed characterizations of five new host galaxies of fast radio bursts (FRBs) discovered with the Australian Square Kilometre Array Pathfinder (ASKAP) and localized to ≾ 1". Combining these galaxies with FRB hosts from the literature, we introduce criteria based on the probability of chance coincidence to define a subsample of 10 highly confident associations (at z = 0.03–0.52), 3 of which correspond to known repeating FRBs. Overall, the FRB-host galaxies exhibit a broad, continuous range of color (M_u − M_r = 0.9–2.0), stellar mass (M_★ = 10⁸ − 6 × 10¹⁰ M_⊙), and star formation rate (SFR = 0.05–10 M_⊙ yr⁻¹) spanning the full parameter space occupied by z 99% c.l.). We measure a median offset of 3.3 kpc from the FRB to the estimated center of the host galaxies and compare the host-burst offset distribution and other properties with the distributions of long- and short-duration gamma-ray bursts (LGRBs and SGRBs), core-collapse supernovae (CC-SNe), and SNe Ia. This analysis rules out galaxies hosting LGRBs (faint, star-forming galaxies) as common hosts for FRBs (>95% c.l.). Other transient channels (SGRBs, CC-, and SNe Ia) have host-galaxy properties and offsets consistent with the FRB distributions. All of the data and derived quantities are made publicly available on a dedicated website and repository

Host Galaxy Properties and Offset Distributions of Fast Radio Bursts: Implications for their Progenitors

We present observations and detailed characterizations of five new host galaxies of fast radio bursts (FRBs) discovered with the Australian Square Kilometre Array Pathfinder (ASKAP) and localized to $\lesssim 1''$. Combining these galaxies with FRB hosts from the literature, we introduce criteria based on the probability of chance coincidence to define a sub-sample of 10 highly-confident associations (at $z=0.03-0.52$), three of which correspond to known repeating FRBs. Overall, the FRB host galaxies exhibit a broad, continuous range of color ($M_u-M_r = 0.9 - 2.0$), stellar mass ($M_\star = 10^{8} - 6\times 10^{10}\,M_{\odot}$), and star-formation rate (${\rm SFR} = 0.05 - 10\,M_{\odot}\,{\rm yr}^{-1}$) spanning the full parameter space occupied by $z<0.5$ galaxies. However, they do not track the color-magnitude, SFR-$M_\star$, nor BPT diagrams of field galaxies surveyed at similar redshifts. There is an excess of "green valley" galaxies and an excess of emission-line ratios indicative of a harder radiation field than that generated by star-formation alone. From the observed stellar mass distribution, we rule out the hypothesis that FRBs strictly track stellar mass in galaxies ($>99\%$ c.l.). We measure a median offset of 3.3 kpc from the FRB to the estimated center of the host galaxies and compare the host-burst offset distribution and other properties with the distributions of long- and short-duration gamma-ray bursts (LGRBs and SGRBs), core-collapse supernovae (CC-SNe), and Type Ia SNe. This analysis rules out galaxies hosting LGRBs (faint, star-forming galaxies) as common hosts for FRBs ($>95\%$ c.l.). Other transient channels (SGRBs, CC- and Type Ia SNe) have host galaxy properties and offsets consistent with the FRB distributions. All of the data and derived quantities are made publicly available on a dedicated website and repository.Comment: Accepted for publication in ApJ. All data are publicly available at https://frbhosts.org and https://github.com/FRBs/FRB. Version 2 of manuscript includes updated FRB uncertainty estimate