Valorization of lignocellulosic fibres of paper waste into levulinic acid using solid and aqueous Brønsted acid

Chen, Season S.,Wang, Lei,Yu, Iris K.M.,Tsang, Daniel C.W.,Hunt, Andrew J.,Jé,r&ocirc,me, Franç,ois,Zhang, Shicheng,Ok, Yong Sik,Poon, Chi Sun Elsevier 2018 Bioresource technology Vol.247 No.-

<P><B>Abstract</B></P> <P>This study aims to produce levulinic acid (LA) from paper towel waste in environment-friendly and economically feasible conditions, and evaluate the difference using solid and aqueous Brønsted acids. Direct dehydration of glucose to LA required sufficiently strong Brønsted acidity, where Amberlyst 36 demonstrated rapid production of approximately 30Cmol% of LA in 20min. However, the maximum yield of LA was limited by mass transfer. In contrast, the yield of LA gradually increased to over 40Cmol% in 1M H<SUB>2</SUB>SO<SUB>4</SUB> at 150°C in 60min. The SEM images revealed the conversion in dilute acids under microwave at 150°C resulting in swelling structures of cellulose, which were similar to the pre-treatment process with concentrated acids. Further increase in reaction temperature to 200°C significantly shortened the reaction time from 60 to 2.5min, which saved the energy cost as revealed in preliminary cost analysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 30% of levulinic acid (LA) yielded from paper towel over Amberlyst 36 in 20min. </LI> <LI> Maximum yield of LA was comparable using dilute sulphuric acid at 150 and 200°C. </LI> <LI> Cellulose underwent swelling in dilute acid with microwave heating at 150°C. </LI> <LI> Conversion at 200°C shortened reaction time and reduced total energy consumption. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Challenges of tracking extratropical cyclones in regional climate models

Cô,té,, Hé,lè,ne,Grise, Kevin M.,Son, Seok-Woo,de Elí,a, Ramó,n,Frigon, Anne Springer-Verlag 2015 Climate dynamics Vol.44 No.11

THE NEXT GENERATION VIRGO CLUSTER SURVEY. XXII. SHELL FEATURE EARLY-TYPE DWARF GALAXIES IN THE VIRGO CLUSTER

Paudel, Sanjaya,Smith, Rory,Duc, Pierre-Alain,Cô,té,, Patrick,Cuillandre, Jean-Charles,Ferrarese, Laura,Blakeslee, John P.,Boselli, Alessandro,Cantiello, Michele,Gwyn, S. D. J.,Guhathakurta American Astronomical Society 2017 The Astrophysical Journal Vol.834 No.1

<P>The Next Generation Virgo Cluster Survey is a deep (with a 2 sigma detection limit mu g = 29 mag arcsec(-2) in the g-band) optical panchromatic survey targeting the Virgo cluster from its core to virial radius, for a total areal coverage of 104 square degrees. As such, the survey is well suited for the study of galaxies' outskirts, haloes, and low surface brightness features that arise from dynamical interactions within the cluster environment. We report the discovery of extremely faint (mu g > 25 mag arcsec(-2)) shells in three Virgo cluster early-type dwarf galaxies: VCC. 1361, VCC. 1447, and VCC. 1668. Among them, VCC. 1447 has an absolute magnitude Mg = -11.71 mag and is the least massive galaxy with a shell system discovered to date. We present a detailed study of these low surface brightness features. We detect between three and four shells in each of our galaxies. Within the uncertainties, we find no evidence of a color difference between the galaxy main body and shell features. The observed arcs of the shells are located up to several effective radii of the galaxies. We further explore the origin of these low surface brightness features with the help of idealized numerical simulations. We find that a near equal mass merger is best able to reproduce the main properties of the shells, including their quite symmetric appearance and their alignment along the major axis of the galaxy. The simulations provide support for a formation scenario in which a recent merger, between two near-equal mass, gas-free dwarf galaxies, forms the observed shell systems.</P>

Polar aprotic solvent-water mixture as the medium for catalytic production of hydroxymethylfurfural (HMF) from bread waste

Yu, Iris K.M.,Tsang, Daniel C.W.,Chen, Season S.,Wang, Lei,Hunt, Andrew J.,Sherwood, James,De Oliveira Vigier, Karine,Jé,r&ocirc,me, Franç,ois,Ok, Yong Sik,Poon, Chi Sun Elsevier 2017 Bioresource technology Vol.245 No.1

<P><B>Abstract</B></P> <P>Valorisation of bread waste for hydroxymethylfurfural (HMF) synthesis was examined in dimethyl sulfoxide (DMSO)-, tetrahydrofuran (THF)-, acetonitrile (ACN)-, and acetone-water (1:1v/v), under heating at 140°C with SnCl<SUB>4</SUB> as the catalyst. The overall rate of the process was the fastest in ACN/H<SUB>2</SUB>O and acetone/H<SUB>2</SUB>O, followed by DMSO/H<SUB>2</SUB>O and THF/H<SUB>2</SUB>O due to the rate-limiting glucose isomerisation. However, the formation of levulinic acid (via rehydration) and humins (via polymerisation) was more significant in ACN/H<SUB>2</SUB>O and acetone/H<SUB>2</SUB>O. The constant HMF maxima (26–27mol%) in ACN/H<SUB>2</SUB>O, acetone/H<SUB>2</SUB>O, and DMSO/H<SUB>2</SUB>O indicated that the rates of desirable reactions (starch hydrolysis, glucose isomerisation, and fructose dehydration) relative to undesirable pathways (HMF rehydration and polymerisation) were comparable among these mediums. They also demonstrated higher selectivity towards HMF production over the side reactions than THF/H<SUB>2</SUB>O. This study differentiated the effects of polar aprotic solvent-water mediums on simultaneous pathways during biomass conversion.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bread waste was valorised for the synthesis of HMF, with yields of 26–27mol%. </LI> <LI> Fastest HMF production took place in ACN/H<SUB>2</SUB>O and acetonitrile/H<SUB>2</SUB>O systems. </LI> <LI> Slow glucose isomerization hindered HMF formation in DMSO/H<SUB>2</SUB>O and THF/H<SUB>2</SUB>O. </LI> <LI> Similar HMF selectivity was achieved in ACN/H<SUB>2</SUB>O, acetonitrile/H<SUB>2</SUB>O, and DMSO/H<SUB>2</SUB>O. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

The Horizontal Branch Population of NGC 1851 as Revealed by the Ultraviolet Imaging Telescope (UVIT)

Subramaniam, Annapurni,Sahu, Snehalata,Postma, Joseph E.,Cô,té,, Patrick,Hutchings, J. B.,Darukhanawalla, N.,Chung, Chul,Tandon, S. N.,Rao, N. Kameswara,George, K.,Ghosh, S. K.,Girish, V.,M American Astronomical Society 2017 The Astronomical journal Vol.154 No.6

<P>We present the UV photometry of the globular cluster NGC 1851 using images acquired with the Ultraviolet Imaging Telescope (UVIT) onboard the ASTROSAT satellite. Point-spread function fitting photometric data derived from images in two far-UV (FUV) filters and one near-UV (NUV) filter are used to construct color-magnitude diagrams (CMDs), in combination with HST and ground-based optical photometry. In the FUV, we detect only the bluest part of the cluster horizontal branch (HB); in the NUV, we detect the full extent of the HB, including the red HB, blue HB, and a small number of RR Lyrae stars. UV variability was detected in 18 RR Lyrae stars, and three new variables were also detected in the central region. The UV/optical CMDs are then compared with isochrones of different age and metallicity (generated using Padova and BaSTI models) and synthetic HB (using helium-enhanced Y2 models). We are able to identify two populations among the HB stars, which are found to have either an age range of 10-12. Gyr, or a range in Y-ini of 0.23-0.28, for a metallicity of [Fe/H] = -1.2 to -1.3. These estimations from the UV CMDs are consistent with those from optical studies. The almost-complete sample of the HB stars tends to show a marginal difference in spatial/azimuthal distribution among the blue and red HB stars. Thus, this study showcases the capability of UVIT, with its excellent resolution and large field of view, to study the hot stellar population in Galactic globular clusters.</P>

Blood cell assisted in vivo Particle Image Velocimetry using the confocal laser scanning microscope.

Choi, Sung Min,Kim, Wi Han,Cô,té,, Daniel,Park, Cheol-Woo,Lee, Ho Optical Society of America 2011 Optics express Vol.19 No.5

<P>We demonstrated the feasibility of blood cell assisted in vivo Particle Image Velocimetry using confocal microscopy. Blood flow of skin vessel in a mouse was non-invasively imaged in vivo using a confocal microscopy. The video-rate confocal microscope was used to monitor the motion of the blood cells in the capillary of a live mouse ear. The home-built confocal laser scanning microscopy allowed us to take images at the acquisition rate of 30 frames per second. The individual blood cells could be distinguished from other cells and the trajectory of the each cell could be followed in the sequential images. The acquired confocal images were used to get the velocity profile of the in vivo blood flow in conjunction with the Particle Image Velocimetry (PIV), without injecting any exogenous nano/micro particles into the mouse. We were able to measure the blood velocity up to a few hundreds µm/sec for various vessels in a live mouse. Because there is no need for the injection of the exogenous tracing particles, it is expected that we could apply the current technology to the study of human capillary blood stream.</P>