Publications by authors named "Joshua R Williams"

Article Synopsis
  • The study explored how different roasting degrees of coffee affect caffeine content and extraction yields, using 30 unique combinations of coffee varieties, roasting degrees, and brew times.
  • An AeroPress was used for brewing, and measurement techniques included refractometry for extraction yield and HPLC for caffeine content, showing that higher roasting degrees increased seed porosity but generally reduced extraction yields.
  • Interestingly, while caffeine concentrations were lower in dark roasts compared to light and medium roasts under the same brewing conditions, dark roasts had higher caffeine levels when extraction yields were matched, suggesting complex interactions between roasting and brewing processes.
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Background: Life science research is moving quickly towards large-scale experimental designs that are comprised of multiple tissues, time points, and samples. Omic time-series experiments offer answers to three big questions: what collective patterns do most analytes follow, which analytes follow an identical pattern or synchronize across multiple cohorts, and how do biological functions evolve over time. Existing tools fall short of robustly answering and visualizing all three questions in a unified interface.

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During the 20th century the impacts of industrialization and urbanization in Galveston Bay resulted in significant shifts in trace metals (Hg, Pb, Ni, Zn) and vascular plant biomarkers (lignin phenols) recorded within the surface sediments and sediment cores profile. A total of 22 sediment cores were collected in Galveston Bay in order to reconstruct the historical input of Hg, Pb, Ni, Zn and terrestrial organic matter. Total Hg (T-Hg) concentration ranged between 6 and 162 ng g in surface sediments, and showed decreasing concentrations southward from the Houston Ship Channel (HSC) toward the open estuary.

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A series of samples ((AB)(x)(CD)(y))(z) were prepared containing both short repeat units (AB and CD) and long repeat units ((AB)(x)(CD)(y)), where the short repeat units were designed to have the composition appropriate to form square M(4)Sb(12) skutterudites (M = Fe, Co, or Ir; square = vacancy, La, or Y). X-ray diffraction and reflectivity were used to follow the evolution of the films from amorphous, layered materials to crystalline skutterudite superlattices as a function of annealing temperature and time. In all cases, the short repeat units interdiffused and crystallized the expected skutterudite, while the long repeat period persisted after annealing.

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The nucleation energy of a series of La(x)Fe(y)Sb(z) modulated elemental reactants was measured as a function of the Fe/Sb ratio over a large composition range while holding the La content constant. The nucleation energy of the ternary compound La(0.5)Fe(4)Sb(12) with the skutterudite crystal structure was found to depend very strongly on the Fe/Sb ratio in the modulated elemental reactant, with a higher nucleation energy as the Fe/Sb ratio is moved away from the 1:3 stoichiometric value.

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A new metastable binary compound with the skutterudite crystal structure has been synthesized from modulated elemental reactants, through an amorphous intermediate, using a novel low-temperature synthesis technique. The amorphous reaction intermediate undergoes nucleation at 87 degrees C, an extremely low temperature for solid-state reactions. When heated above 350 degrees C, the metastable phase NiSb(3) disproportionates into the thermodynamically stable phases NiSb(2) and Sb.

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