University of Massachusetts Boston

About: University of Massachusetts Boston is a education organization based out in Boston, Massachusetts, United States. It is known for research contribution in the topics: Population & Health care. The organization has 6541 authors who have published 12918 publications receiving 411731 citations. The organization is also known as: UMass Boston.

Catalytic pyrolysis of solid biomass and related biofuels, aromatic, and olefin compounds

Abstract: This invention relates to compositions and methods for fluid hydrocarbon product, and more specifically, to compositions and methods for fluid hydrocarbon product via catalytic pyrolysis. Some embodiments relate to methods for the production of specific aromatic products (e.g., benzene, toluene, naphthalene, xylene, etc.) via catalytic pyrolysis. Some such methods may involve the use of a composition comprising a mixture of a solid hydrocarbonaceous material and a heterogeneous pyrolytic catalyst component. In some embodiments, the mixture may be pyrolyzed at high temperatures (e.g., between 500 °C and 1000 °C). The pyrolysis may be conducted for an amount of time at least partially sufficient for production of discrete, identifiable biofuel compounds. Some embodiments involve heating the mixture of catalyst and hydrocarbonaceous material at high rates (e.g., from about 50 °C per second to about 1000 0C per second). The methods described herein may also involve the use of specialized catalysts. For example, in some cases, zeolite catalysts may be used; optionally, the catalysts used herein may have high silica to alumina molar ratios. In some instances, the composition fed to the pyrolysis reactor may have a relatively high catalyst to hydrocarbonaceous material mass ratio (e.g., from about 5: 1 to about 20:1).

Si-Based GeSn Lasers with Wavelength Coverage of 2–3 μm and Operating Temperatures up to 180 K

Abstract: A Si-based monolithic laser is strongly desired for the full integration of Si-photonics. Lasing from the direct bandgap group-IV GeSn alloy has opened a new avenue, different from the hybrid III–V-on-Si integration approach. We demonstrated optically pumped GeSn lasers on Si with broad wavelength coverage from 2 to 3 μm. The GeSn alloys were grown using newly developed approaches with an industry standard chemical vapor deposition reactor and low-cost commercially available precursors. The achieved maximum Sn composition of 17.5% exceeded the generally acknowledged Sn incorporation limits found with similar deposition chemistries. The highest lasing temperature was measured as 180 K with the active layer thickness as thin as 260 nm. The unprecedented lasing performance is mainly due to the unique growth approaches, which offer high-quality epitaxial materials. The results reported in this work show a major advance toward Si-based mid-infrared laser sources for integrated photonics.

Consumers’ Willingness to Pay for Organic Products: A Case From Kathmandu Valley

Abstract: This paper presents the consumers' willingness to pay a price premium for organic products in Kathmandu Valley. The Nepal Permaculture Group surveyed 180 consumers using semi-structured questionnaires to examine peoples' perception about organic products and assess their willingness to pay for such products. The study revealed that all respondents are willing to pay price premium, but the level of acceptability varied considerably. A total of 58% of the consumers are willing to pay 6- 20% price premium, whereas 13% are willing to pay up to 50% premium. The average premium was estimated about 30%. About 39% of the respondents feel the extra cost for organic products is reasonable, while 27% considered it too high. The survey also suggested that the consumption of organic products is increasing; however, product development and innovations in certification, processing, labeling and packaging are needed to further stimulate demand. Key words: Certification; Consumer perception; Organic products; Price premium; Processing; Willingness to pay The Journal of Agriculture and Environment Vol:10, Jun.2009 Page: 15-26

Universal interferometric signatures of a black hole’s photon ring

Abstract: The Event Horizon Telescope image of the supermassive black hole in the galaxy M87 is dominated by a bright, unresolved ring. General relativity predicts that embedded within this image lies a thin “photon ring,” which is composed of an infinite sequence of self-similar subrings that are indexed by the number of photon orbits around the black hole. The subrings approach the edge of the black hole “shadow,” becoming exponentially narrower but weaker with increasing orbit number, with seemingly negligible contributions from high-order subrings. Here, we show that these subrings produce strong and universal signatures on long interferometric baselines. These signatures offer the possibility of precise measurements of black hole mass and spin, as well as tests of general relativity, using only a sparse interferometric array.