| 1. |
- Kumar, Vinod, et al.
(författare)
-
Bread waste : A potential feedstock for sustainable circular biorefineries
- 2023
-
Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 369
-
Forskningsöversikt (refereegranskat)abstract
- The management of staggering volume of food waste generated (∼1.3 billion tons) is a serious challenge. The readily available untapped food waste can be promising feedstock for setting up biorefineries and one good example is bread waste (BW). The current review emphasis on capability of BW as feedstock for sustainable production of platform and commercially important chemicals. It describes the availability of BW (>100 million tons) to serve as a feedstock for sustainable biorefineries followed by examples of platform chemicals which have been produced using BW including ethanol, lactic acid, succinic acid and 2,3-butanediol through biological route. The BW-based production of these metabolites is compared against 1G and 2G (lignocellulosic biomass) feedstocks. The review also discusses logistic and supply chain challenges associated with use of BW as feedstock. Towards the end, it is concluded with a discussion on life cycle analysis of BW-based production and comparison with other feedstocks.
|
|
| 2. |
- Gangopadhyay, Anjasha, et al.
(författare)
-
Optical studies of two stripped-envelope supernovae – SN 2015ap (Type Ib) and SN 2016P (Type Ic)
- 2020
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 497:3, s. 3770-3789
-
Tidskriftsartikel (refereegranskat)abstract
- We present the photometric and spectroscopic studies of a Type Ib SN 2015ap and a Type Ic SN 2016P. SN 2015ap is one of the bright (MV = −18.04 mag) Type Ib while SN 2016P lies at an average value among the Type Ic SNe (MV = −17.53 mag). Bolometric light-curve modelling of SNe 2015ap and 2016P indicates that both the SNe are powered by 56Ni + magnetar model with 56Ni masses of 0.01 and 0.002 M⊙, ejecta masses of 3.75 and 4.66 M⊙, spin period P0 of 25.8 and 36.5 ms, and magnetic field Bp of 28.39 × 1014 and 35.3 × 1014 G, respectively. The early spectra of SN 2015ap show prominent lines of He with a ‘W’ feature due to Fe complexes while other lines of Mg ii, Na i, and Si ii are present in both SNe 2015ap and 2016P. Nebular phase [O i] profile indicates an asymmetric profile in SN 2015ap. The [O i]/[Ca ii] ratio and nebular spectral modelling of SN 2015ap hint towards a progenitor mass between 12 and 20 M⊙.
|
|
| 3. |
- Husain, Sajid, et al.
(författare)
-
Observation of Skyrmions at Room Temperature in Co2FeAl Heusler Alloy Ultrathin Film Heterostructures
- 2019
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Magnetic skyrmions are topological spin-textures having immense potential for energy efficient spintronic devices. Here, we report the observation of stable skyrmions in unpatterned Ta/Co2FeAl(CFA)/MgO thin film heterostructures at room temperature in remnant state employing magnetic force microscopy. It is shown that these skyrmions consisting of ultrathin ferromagnetic CFA Heusler alloy result from strong interfacial Dzyaloshinskii-Moriya interaction (i-DMI) as evidenced by Brillouin light scattering measurements, in agreement with the results of micromagnetic simulations. We also emphasize on room temperature observation of multiple skyrmions which can be stabilized for suitable combinations of CFA layer thickness, perpendicular magnetic anisotropy, and i-DMI. These results provide a significant step towards designing of room temperature spintronic devices based on skyrmions in full Heusler alloy based thin films.
|
|
| 4. |
- Kasliwal, Mansi M., et al.
(författare)
-
Kilonova Luminosity Function Constraints Based on Zwicky Transient Facility Searches for 13 Neutron Star Merger Triggers during O3
- 2020
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 905:2
-
Tidskriftsartikel (refereegranskat)abstract
- We present a systematic search for optical counterparts to 13 gravitational wave (GW) triggers involving at least one neutron star during LIGO/Virgo's third observing run (O3). We searched binary neutron star (BNS) and neutron star black hole (NSBH) merger localizations with the Zwicky Transient Facility (ZTF) and undertook follow-up with the Global Relay of Observatories Watching Transients Happen (GROWTH) collaboration. The GW triggers had a median localization area of 4480 deg(2), a median distance of 267 Mpc, and false-alarm rates ranging from 1.5 to 10(-25) yr(-1). The ZTF coverage in the g and r bands had a median enclosed probability of 39%, median depth of 20.8 mag, and median time lag between merger and the start of observations of 1.5 hr. The O3 follow-up by the GROWTH team comprised 340 UltraViolet/Optical/InfraRed (UVOIR) photometric points, 64 OIR spectra, and three radio images using 17 different telescopes. We find no promising kilonovae (radioactivity-powered counterparts), and we show how to convert the upper limits to constrain the underlying kilonova luminosity function. Initially, we assume that all GW triggers are bona fide astrophysical events regardless of false-alarm rate and that kilonovae accompanying BNS and NSBH mergers are drawn from a common population; later, we relax these assumptions. Assuming that all kilonovae are at least as luminous as the discovery magnitude of GW170817 (-16.1 mag), we calculate that our joint probability of detecting zero kilonovae is only 4.2%. If we assume that all kilonovae are brighter than -16.6 mag (the extrapolated peak magnitude of GW170817) and fade at a rate of 1 mag day(-1) (similar to GW170817), the joint probability of zero detections is 7%. If we separate the NSBH and BNS populations based on the online classifications, the joint probability of zero detections, assuming all kilonovae are brighter than -16.6 mag, is 9.7% for NSBH and 7.9% for BNS mergers. Moreover, no more than <57% (<89%) of putative kilonovae could be brighter than -16.6 mag assuming flat evolution (fading by 1 mag day(-1)) at the 90% confidence level. If we further take into account the online terrestrial probability for each GW trigger, we find that no more than <68% of putative kilonovae could be brighter than -16.6 mag. Comparing to model grids, we find that some kilonovae must have M-ej M, X-lan > 10(-4), or > 30 degrees to be consistent with our limits. We look forward to searches in the fourth GW observing run; even 17 neutron star mergers with only 50% coverage to a depth of -16 mag would constrain the maximum fraction of bright kilonovae to <25%.
|
|
| 5. |
- Perley, Daniel A., et al.
(författare)
-
The fast, luminous ultraviolet transient AT2018cow : extreme supernova, or disruption of a star by an intermediate-mass black hole?
- 2019
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 484:1, s. 1031-1049
-
Tidskriftsartikel (refereegranskat)abstract
- Wide-field optical surveys have begun to uncover large samples of fast (t(rise) less than or similar to 5 d), luminous (M-peak < 18), blue transients. While commonly attributed to the breakout of a supernova shock into a dense wind, the great distances to the transients of this class found so far have hampered detailed investigation of their properties. We present photometry and spectroscopy from a comprehensive worldwide campaign to observe AT 2018cow (ATLAS 18qqn), the first fast-luminous optical transient to be found in real time at low redshift. Our first spectra (<2 days after discovery) are entirely featureless. A very broad absorption feature suggestive of near-relativistic velocities develops between 3 and 8 days, then disappears. Broad emission features of H and He develop after >10 days. The spectrum remains extremely hot throughout its evolution, and the photospheric radius contracts with time (receding below R < 10 (14) cm after 1 month). This behaviour does not match that of any known supernova, although a relativistic jet within a fallback supernova could explain some of the observed features. Alternatively, the transient could originate from the disruption of a star by an intermediate-mass black hole, although this would require long-lasting emission of highly super-Eddington thermal radiation. In either case, AT 2018cow suggests that the population of fast luminous transients represents a new class of astrophysical event. Intensive follow-up of this event in its late phases, and of any future events found at comparable distance, will be essential to better constrain their origins.
|
|
| 6. |
- Roy, Rupak, et al.
(författare)
-
SN 2007uy-metamorphosis of an aspheric Type Ib explosion
- 2013
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 434:3, s. 2032-2050
-
Tidskriftsartikel (refereegranskat)abstract
- The supernovae (SNe) of Type Ibc are rare and the detailed characteristics of these explosions have been studied only for a few events. Unlike Type II SNe, the progenitors of Type Ibc have never been detected in pre-explosion images. So, to understand the nature of their progenitors and the characteristics of the explosions, investigation of proximate events is necessary. Here we present the results of multiwavelength observations of Type Ib SN 2007uy in the nearby (similar to 29.5 Mpc) galaxy NGC 2770. Analysis of the photometric observations revealed this explosion as an energetic event with peak absolute R-band magnitude -18.5 +/- 0.16, which is about 1 mag brighter than the mean value (-17.6 +/- 0.6) derived for well observed Type Ibc events. The SN is highly extinguished, E(B - V) = 0.63 +/- 0.15 mag, mainly due to foreground material present in the host galaxy. From optical light curve modelling we determine that about 0.3 M-circle dot radioactive Ni-56 is produced and roughly 4.4 M-circle dot material is ejected during this explosion with liberated energy similar to 15 x 10(51) erg, indicating the event to be an energetic one. Through optical spectroscopy, we have noticed a clear aspheric evolution of several line-forming regions, but no dependency of asymmetry is seen on the distribution of Ni-56 inside the ejecta. The SN shock interaction with the circumstellar material is clearly noticeable in radio follow-up, presenting a synchrotron self-absorption dominated light curve with a contribution of free-free absorption during the early phases. Assuming a Wolf-Rayet (WR) star, with wind velocity greater than or similar to 10(3) km s(- 1), as a progenitor, we derive a lower limit to the mass-loss rate inferred from the radio data as M 2.4 10(-5) M-circle dot yr(-1), which is consistent with the results obtained for other Type Ibc SNe bright at radio frequencies.
|
|
| 7. |
- Andrews, Jennifer E., et al.
(författare)
-
SN 2017gmr : An Energetic Type II-P Supernova with Asymmetries
- 2019
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 885:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present high-cadence UV, optical, and near-infrared data on the luminous Type II-P supernova SN;2017gmr from hours after discovery through the first 180 days. SN;2017gmr does not show signs of narrow, high-ionization emission lines in the early optical spectra, yet the optical light-curve evolution suggests that an extra energy source from circumstellar medium (CSM) interaction must be present for at least 2 days after explosion. Modeling of the early light curve indicates a ?500 R progenitor radius, consistent with a rather compact red supergiant, and late-time luminosities indicate that up to 0.130;;0.026 M of Ni-56 are present, if the light curve is solely powered by radioactive decay, although the Ni-56 mass may be lower if CSM interaction contributes to the post-plateau luminosity. Prominent multipeaked emission lines of H? and [O i] emerge after day 154, as a result of either an asymmetric explosion or asymmetries in the CSM. The lack of narrow lines within the first 2 days of explosion in the likely presence of CSM interaction may be an example of close, dense, asymmetric CSM that is quickly enveloped by the spherical supernova ejecta.
|
|
| 8. |
- Kumari, Poonam, et al.
(författare)
-
Plants and endophytes interaction : a “secret wedlock” for sustainable biosynthesis of pharmaceutically important secondary metabolites
- 2023
-
Ingår i: Microbial Cell Factories. - : BioMed Central Ltd. - 1475-2859. ; 22:1
-
Forskningsöversikt (refereegranskat)abstract
- Many plants possess immense pharmacological properties because of the presence of various therapeutic bioactive secondary metabolites that are of great importance in many pharmaceutical industries. Therefore, to strike a balance between meeting industry demands and conserving natural habitats, medicinal plants are being cultivated on a large scale. However, to enhance the yield and simultaneously manage the various pest infestations, agrochemicals are being routinely used that have a detrimental impact on the whole ecosystem, ranging from biodiversity loss to water pollution, soil degradation, nutrient imbalance and enormous health hazards to both consumers and agricultural workers. To address the challenges, biological eco-friendly alternatives are being looked upon with high hopes where endophytes pitch in as key players due to their tight association with the host plants. The intricate interplay between plants and endophytic microorganisms has emerged as a captivating subject of scientific investigation, with profound implications for the sustainable biosynthesis of pharmaceutically important secondary metabolites. This review delves into the hidden world of the "secret wedlock" between plants and endophytes, elucidating their multifaceted interactions that underpin the synthesis of bioactive compounds with medicinal significance in their plant hosts. Here, we briefly review endophytic diversity association with medicinal plants and highlight the potential role of core endomicrobiome. We also propose that successful implementation of in situ microbiome manipulation through high-end techniques can pave the way towards a more sustainable and pharmaceutically enriched future.
|
|
| 9. |
- Shanmugam, Kavitha, 1992-
(författare)
-
Circularity Assessment of Water and Waste in Cities : A Proposed Framework for Sustainable Performance Evaluation using LCA and LCC
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Urbanization is a global phenomenon, happening on a massive scale and at a rapid rate, with 68% of the planet’s population predicted to be living in cities by 2050 (UN-DESA, 2018). The sustainability of a city (Goal 11 of UN SDGs) undergoing rapid urbanization depends on its ability to maintain a low consumption of resources and materials at any given time (referred to as the urban metabolic rate), whilst simultaneously providing essential municipal services to its inhabitants, such as a water supply, wastewater treatment and solid waste management. The latter must comply with circular economy principles, meaning recovery of byproducts, prevention of discharge of toxic pollutants, and avoidance of landfill usage. The appended papers in the thesis (Papers I–V) describe sustainable assessments of wastewater and waste services to increase their degree of circularity, using tools such as Life Cycle Assessment (LCA) and Life Cycle Costing (LCC). Paper I describes the environmental performance of using the biogas from a Wastewater Treatment Plant (WWTP) and converting it to Liquefied Biomethane (LBM), which can used as fuel in Tractor-Trailers (TT). Overall, the study suggests that changing from diesel to LBM fuel improves the environmental performance of TT. However, the magnitude of environmental benefit depends on an alternate source of electricity required for operation of the WWTP. Paper II evaluates the Social Cost-Benefit Analysis (SCBA) of Compressed Biomethane (CBM) obtained from a food waste digestion plant in Mumbai, India for use as a fuel in transit buses. SCBA results indicate that the food waste-based CBM model can save 6.86 billion Indian rupees (99.4 million USD) annually for Mumbai. Paper III describes the Sustainable Return on Investment (SROI) of lightweight Advanced High Strength Steel (AHSS) and Carbon Fiber Reinforced Polymer (CFRP) intensive multi-material Body in White (BIW) for automobiles. The SROI of CFRP BIWs is maximized when carbon fiber production uses energy from a low carbon-intensity electric grid or decentralized sources such as waste-to-energy incineration plants. Paper IV assesses the ecoefficiency of a thermal insulation panel that consists of a Polyurethane (PU) foam core sandwiched between two epoxy composite skins, prepared by reinforcing Glass Fibers (GF) and SFA (Silanized Fly Ash) in epoxy resin. The results revealed that the ecoefficiency of the composite panels is positive (47%) and superior to that of market incumbent alternatives with PU foam or rockwool cores and steel skins. Paper V quantifies the Total Cost to Society (TCS) (sum of private cost and environmental externalities cost) of a centralized urban WWTP, including the operation as well as byproduct utilization stream. The environmental performance and circular compliance are both factored in, when determining the TCS of a WWTP. The results revealed savings of 1.064 million USD, which include direct and indirect revenues to the plant, as well as avoidance costs attributed to environmental externalities. Based on the studies described in4these papers, a five-stage assessment framework for determining the overall sustainability performance of essential treatment services in a city is proposed in this thesis. The framework considers the combined effect of urban metabolic features and initiatives aimed at improving circular compliance of essential services.
|
|
