Acidity and Antioxidant Activity of Cold Brew Coffee.

The acidity and antioxidant activity of cold brew coffee were investigated using light roast coffees from Brazil, two regions of Ethiopia, Columbia, Myanmar, and Mexico. The concentrations of three caffeoylquinic acid (CQA) isomers were also determined. Cold brew coffee chemistry was compared to that of hot brew coffee prepared with the same grind-to-coffee ratio. The pH values of the cold and hot brew samples were found to be comparable, ranging from 4.85 to 5.13. The hot brew coffees were found to have higher concentrations of total titratable acids, as well as higher antioxidant activity, than that of their cold brew counterparts. It was also noted that both the concentration of total titratable acids and antioxidant activity correlated poorly with total CQA concentration in hot brew coffee. This work suggests that the hot brew method tends to extract more non-deprotonated acids than the cold brew method. These acids may be responsible for the higher antioxidant activities observed in the hot brew coffee samples

Physical and chemical differentiation of the luminous star-forming region W49A - Results from the JCMT Spectral Legacy Survey

The massive and luminous star-forming region W49A is a well known Galactic candidate to probe the physical conditions and chemistry similar to those expected in external starburst galaxies. We aim to probe the physical and chemical structure of W49A on a spatial scale of ~0.8 pc based on the JCMT Spectral Legacy Survey, which covers the frequency range between 330 and 373 GHz. The wide 2x2 arcminutes field and the high spectral resolution of the HARP instrument on JCMT provides information on the spatial structure and kinematics of the cloud. For species where multiple transitions are available, we estimate excitation temperatures and column densities. We detected 255 transitions corresponding to 60 species in the 330-373 GHz range at the center position of W49A. Excitation conditions can be probed for 16 molecules. The chemical composition suggests the importance of shock-, PDR-, and hot core chemistry. Many molecular lines show a significant spatial extent across the maps including high density tracers (e.g. HCN, HNC, CS, HCO+) and tracers of UV-irradiation (e.g. CN and C2H). Large variations are seen between the sub-regions with mostly blue-shifted emission toward the Eastern tail, mostly red-shifted emission toward the Northern clump, and emission peaking around the expected source velocity toward the South-west clump. A comparison of column density ratios of characteristic species observed toward W49A to Galactic PDRs suggests that while the chemistry toward the W49A center is driven by a combination of UV-irradiation and shocks, UV-irradiation dominates for the Northern Clump, Eastern tail, and South-west clump regions. A comparison to a starburst galaxy and an AGN suggests similar C2H, CN, and H2CO abundances (with respect to the dense gas tracer 34CS) between the ~0.8 pc scale probed for W49A and the >1 kpc regions in external galaxies with global star-formation.Comment: Proposed for acceptance in A&A, abstract abridge

An Investigation of the Kinetics and Equilibrium Chemistry of Cold-Brew Coffee: Caffeine and Chlorogenic Acid Concentrations as a Function of Roasting Temperature and Grind Size

Abstract: Recently, both small and large commercial coffee brewers have begun offering cold-brew coffee drinks to customers with the claims that these cold-water extracts contain fewer bitter acids due to brewing conditions (Toddy website, 2016) while still retaining the flavor profile. Dunkin Donuts’ website suggests that the cold-water and long brewing times allow the coffee to reach “... its purest form.” With very little research existent on the chemistry of cold brew coffee consumers are left to the marketing strategies of Starbucks and other companies regarding the contents of cold-brew coffee. This research analyzes the caffeine and chlorogenic acid (3-CGA) content of cold-brew coffee as a function of brewing time, grind size, and roasting temperature of coffee beans sourced from the Kona region of Hawaii using high pressure liquid chromatography (HPLC). Coarse and medium grinds of both dark and medium roasts were analyzed by mixing 350mL of filtered water with 35g of coffee grinds under constant stirring at 20°C. Sampling was performed every 15 minutes for the first hour, then every 30 minutes for the next ten to twelve hours, with a final sample being drawn at 24hours. Equilibrium concentrations for both 3-CGA and caffeine were reached following 600 minutes. The caffeine concentrations ranged from 935mg/L to 1475mg/L. Variation was seen as a function of roasting temperature, and less so grind size. The 3-CGA concentrations were found to range from 345mg/L to 547mg/L. In both cases, the medium roast coarse grind coffee produced the highest concentrations of caffeine and 3-CGA while dark roast coarse grind produced the lowest concentrations of caffeine and 3-CGA. Hot brew experiments agreed well with caffeine and 3-CGA extraction concentrations in both dark roast coffees, showing very similar final concentrations. The medium roast coffees showed deviation from the hot brew coffees with respect to caffeine, indicating the need for additional experimentation to determine the role of water temperature in the availability of caffeine during extraction

Neutrino-Neutrino Scattering and Matter-Enhanced Neutrino Flavor Transformation in Supernovae

We examine matter-enhanced neutrino flavor transformation ($\nu_{\tau(\mu)}\rightleftharpoons\nu_e$) in the region above the neutrino sphere in Type II supernovae. Our treatment explicitly includes contributions to the neutrino-propagation Hamiltonian from neutrino-neutrino forward scattering. A proper inclusion of these contributions shows that they have a completely negligible effect on the range of $\nu_e$-$\nu_{\tau(\mu)}$ vacuum mass-squared difference, $\delta m^2$, and vacuum mixing angle, $\theta$, or equivalently $\sin^22\theta$, required for enhanced supernova shock re-heating. When neutrino background effects are included, we find that $r$-process nucleosynthesis from neutrino-heated supernova ejecta remains a sensitive probe of the mixing between a light $\nu_e$ and a $\nu_{\tau(\mu)}$ with a cosmologically significant mass. Neutrino-neutrino scattering contributions are found to have a generally small effect on the $(\delta m^2,\ \sin^22\theta)$ parameter region probed by $r$-process nucleosynthesis. We point out that the nonlinear effects of the neutrino background extend the range of sensitivity of $r$-process nucleosynthesis to smaller values of $\delta m^2$.Comment: 38 pages, tex, DOE/ER/40561-150-INT94-00-6

The interplay of millets and rice in Neolithic central China: Integrating phytoliths into the archaeobotany of Baligang

Baligang is a Neolithic site with a long occupation, from before 6300. BC up to the first millennium BC, although the bulk of excavated finds and archaeobotanical evidence from the site comes from the Yangshao, Qujialing, Shijiahe and Longshan (4300-1800. BC). The cultural group affiliation of the site varies between northern (Yangshao and Longshan) and southern (Qujialing and Shijiahe) cultural connections. The earliest occupation of the site represents a pre-Yangshao society with early cultivation of rice (Oryza). In later periods Baligang has evidence for mixed farming of both rice and millets (Setaria italica and Panicum miliaceum), although rice is the most prominent crop in the phytolith record throughout the occupation. Wetland rice cultivation is indicated throughout the Yangshao, Qujialing, Shijiahe and Late Longshan periods. However, there is a shift towards better watered rice in the Qujialing and Shijiahe phytolith assemblages, indicated by a decline in sedges (Cyperaceae) alongside occurrence of sponge spicules and diatoms. These data suggest deeper flooding of rice fields in order to suppress weeds and increase productivity, indicating that the ecology of rice cultivation changed over time. In the Late Longshan period, when millet became more prominent and the cultural influence shifted northwards, it appears that more sedge-infested and weedy rice fields became the norm, suggesting a decline in rice cultivation intensity, perhaps connected to influences of cultivation practices from the north. In addition, we can infer aspects of the organisation of crop-processing from the phytolith evidence. In the Yangshao period the remains consist of mostly dehusking waste from the final processing, suggesting storage of a more processed crop and therefore larger scale, more communal post-harvest processing. By contrast this declined in the subsequent period with more evidence for primary winnowing waste indicating a shift towards smaller social scales of harvesting and processing, such as smaller household groups replacing a more communal approach. The household-level of processing is most evident in the Late Longshan period

Physiochemical Characteristics of Hot and Cold Brew Coffee Chemistry: The Effects of Roast Level and Brewing Temperature on Compound Extraction.

The role of roasting in cold brew coffee chemistry is poorly understood. The brewing temperature influences extraction processes and may have varying effects across the roast spectrum. To understand the relationship between brew temperature and roast temperature, hot and cold brew coffees were prepared from Arabica Columbian coffee beans roasted to light, medium, and dark levels. Chemical and physical parameters were measured to investigate the relationships among degree of roast, water temperature, and key characteristics of resulting coffees. Cold brew coffees showed differential extraction marked by decreased acidity, lower concentration of browned compounds, and fewer TDS indicating that cold water brewing extracts some compounds less effectively than hot water brewing. Compounds in coffee did exhibit sensitivity to degree of roast, with darker roasts resulting in decreased concentrations for both hot and cold brew coffees. Total antioxidant capacity (TAC) was only sensitive to degree of roast in cold brew coffees, while hot brew coffees had a constant TAC for all three roast levels. This indicates that the solid bean matrix and its chemical constituents interact with cold water differently than with hot water. Surface wetting, pore dynamics, and solubility all contribute to the extraction potential during brewing and are all functions of water temperature

Do experiments and astrophysical considerations suggest an inverted neutrino mass hierarchy?

The recent results from the Los Alamos neutrino oscillation experiment together with assumptions of neutrino oscillation solutions for the solar and atmospheric neutrino deficit problems, may place powerful constraints on any putative scheme for neutrino masses and mixings. Assuming the validity of these experiments and assumptions, we argue that a nearly unique spectrum of neutrino masses emerges as a fit, if two additional astrophysical arguments are adopted: (1) the sum of the light neutrino masses is \sim 5\ {\rm eV}, as large scale structure simulations with mixed cold plus hot dark matter seem to suggest; and (2) r-process nucleosynthesis originates in neutrino-heated ejecta from Type II supernovae. In this fit, the masses of the neutrinos must satisfy m_{{\nu}_e} \approx m_{{\nu}_s} \approx 2.7\ {\rm eV} (where {\nu}_e is split from a sterile species, {\nu}_s, by \sim {10}^{-6} \ {\rm eV}) and m_{{\nu}_{\tau}} \approx m_{{\nu}_{\mu}} \approx 1.1\ {\rm eV} (where these species are split by \sim {10}^{-2} \ {\rm eV}). We discuss alternative neutrino mass spectra that are allowed if we decline to adopt certain experiments or astrophysical models

Controlling the exchange interaction using the spin-flip transition of antiferromagnetic spins in Ni81_{81}Fe19_{19} / α\alpha-Fe2_2O3_3

We report studies of exchange bias and coercivity in ferromagnetic Ni$_{81}$Fe$_{19}$ layers coupled to antiferromagnetic (AF) (0001), (11$\bar{2}$0), and (11$\bar{0}$2) $\alpha$-Fe$_2$O$_3$ layers. We show that AF spin configurations which permit spin-flop coupling give rise to a strong uniaxial anisotropy and hence a large coercivity, and that by annealing in magnetic fields parallel to specific directions in the AF we can control either coercivity or exchange bias. In particular, we show for the first time that a reversible temperature-induced spin reorientation in the AF can be used to control the exchange interaction.Comment: 15 pages, 5 figures, submitted to Phys. Rev. Let