Prime Focus Spectrograph (PFS) for the Subaru Telescope: Overview, recent progress, and future perspectives

PFS (Prime Focus Spectrograph), a next generation facility instrument on the 8.2-meter Subaru Telescope, is a very wide-field, massively multiplexed, optical and near-infrared spectrograph. Exploiting the Subaru prime focus, 2394 reconfigurable fibers will be distributed over the 1.3 deg field of view. The spectrograph has been designed with 3 arms of blue, red, and near-infrared cameras to simultaneously observe spectra from 380nm to 1260nm in one exposure at a resolution of ~1.6-2.7A. An international collaboration is developing this instrument under the initiative of Kavli IPMU. The project is now going into the construction phase aiming at undertaking system integration in 2017-2018 and subsequently carrying out engineering operations in 2018-2019. This article gives an overview of the instrument, current project status and future paths forward.Comment: 17 pages, 10 figures. Proceeding of SPIE Astronomical Telescopes and Instrumentation 201

High-solids biphasic CO2-H2O pretreatment of lignocellulosic biomass

A high pressure (200 bar) CO2-H2O process was developed for pretreating lignocellulosic biomass at high-solid contents, while minimizing chemical inputs. Hardwood was pretreated at 20 and 40 (wt.%) solids. Switchgrass, corn stover, big bluestem, and mixed perennial grasses (a co-culture of big bluestem and switchgrass) were pretreated at 40 (wt.%) solids. Operating temperatures ranged from 150 to 250°C, and residence times from 20 s to 60 min. At these conditions a biphasic mixture of an H2-Orich liquid (hydrothermal) phase and a CO2-rich supercritical phase coexist. Following pretreatment, samples were then enzymatically hydrolyzed. Total yields, defined as the fraction of the theoretical maximum, were determined for glucose, hemicellulose sugars, and two degradation products: furfural and 5-hydroxymethylfurfural. Response surfaces of yield as a function of temperature and residence time were compared for different moisture contents and biomass species. Pretreatment at 170°C for 60 min gave glucose yields of 77%, 73%, and 68% for 20 and 40 (wt.%) solids mixed hardwood and mixed perennial grasses, respectively. Pretreatment at 160°C for 60 min gave glucan to glucose yields of 81% for switchgrass and 85% for corn stover. © 2010 Wiley Periodicals, Inc

Two-temperature stage biphasic CO2-H2O pretreatment of lignocellulosic biomass at high solid loadings

Most biomass pretreatment processes for monosaccharide production are run at low-solid concentration (<10wt%) and use significant amounts of chemical catalysts. Biphasic CO 2-H 2O mixtures could provide a more sustainable pretreatment medium while using high-solid contents. Using a stirred reactor for high solids (40wt%, biomass water mixture) biphasic CO 2-H 2O pretreatment of lignocellulosic biomass allowed us to explore the effects of particle size and mixing on mixed hardwood and switchgrass pretreatment. Subsequently, a two-temperature stage pretreatment was introduced. After optimization, a short high-temperature stage at 210°C (16min for hardwood and 1min for switchgrass) was followed by a long low-temperature stage at 160°C for 60min. Glucan to glucose conversion yields of 83% for hardwood and 80% for switchgrass were obtained. Total molar sugar yields of 65% and 55% were obtained for wood and switchgrass, respectively, which consisted of a 10% points improvement over those obtained during our previous study despite a 10-fold increase in particle size. These yields are similar to those obtained with other major pretreatment technologies for wood and within 10% of major technologies for switchgrass despite the absence of chemical catalysts, the use of large particles. © 2011 Wiley Periodicals, Inc

Producing concentrated solutions of monosaccharides using biphasic CO2–H2O mixtures

Sustainably producing concentrated solutions of monosaccharides from biomass is a key challenge facing the conversion of lignocellulosic biomass to biofuels or bioproducts. Most pretreatment and enzymatic hydrolysis processes are run at low-solid concentration (<10 wt%) and use chemical catalysts, while most high-solids enzymatic hydrolysis experiments are performed with air-dried pretreated materials. Using optimally two-temperature stage CO 2-H2O pretreated biomass substrates (210 °C 16 min, 160°C, 60 min for mixed hardwood and 210°C, 1 min, 160°C, 60 min), high-solids enzymatic hydrolysis reactions were performed in a novel high-solids reaction system. With this system, twelve "rotating drum" reactors were run simultaneously in a controlled environment. Without additional chemical catalysts or any drying, two-temperature stage CO2-H2O pretreatment coupled with high-solids enzymatic hydrolysis produced monosaccharide solutions of 185 g L-1 for mixed hardwood and 149 g L-1 for switchgrass. Apart from results obtained with dilute acid pretreated corn stover, these are the most concentrated solutions obtained from biomass pretreatment and enzymatic hydrolysis without substrate drying. The corresponding glucan to glucose yields were above 80% for both types of biomass. Notably, these high yields were obtained because, similar to dilute acid pretreatment but unlike un-catalyzed pretreatment, our approach produced biomass that did not show decreasing yields with increasing enzymatic hydrolysis solid contents. These results suggest that CO2-H2O pretreatment is an attractive alternative to chemically catalyzed processes such as dilute acid pretreatment. © 2012 The Royal Society of Chemistry