| 1. |
- Abelev, Betty, et al.
(författare)
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Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV
- 2013
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 29-41
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Tidskriftsartikel (refereegranskat)abstract
- Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < P-T,P-assoc < P-T,P-trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS Collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and p(T) bins, and the widths show no significant evolution with event multiplicity or p(T). These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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| 2. |
- Abelev, Betty, et al.
(författare)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :11
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Tidskriftsartikel (refereegranskat)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 3. |
- Abelev, Betty, et al.
(författare)
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Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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| 4. |
- Castro, Eulogio, et al.
(författare)
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Pretreatment and bioconversion for valorization of residues of non-edible oilseeds
- 2023
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Ingår i: Agronomy. - : MDPI. - 2073-4395. ; 13:9
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Forskningsöversikt (refereegranskat)abstract
- Biodiesel production currently follows a first-generation model using edible oils as raw materials. Such a production model is unsustainable, considering that it is limited by the high cost of edible oils, competes with the food sector, and is linked to deforestation and other environmental threats. Changing the raw material base to non-edible oils provides an opportunity to increase the sustainability of the biodiesel industry and to avoid conflicts with food production. Processing non-edible oilseeds for extracting the oil to be used for producing biodiesel generates large amounts of residues, such as de-oiled cakes, seed husks, and fruit shells and pods as well as plant stems and leaves resulting from pruning and other agronomy practices. Most of those residues are currently disposed of by burning or used in a suboptimal way. Bioconversion following the sugar platform route, anaerobic digestion, or enzyme production provides means for upgrading them to advanced biofuels and high-added value products. Bioconversion of plant biomass, including oilseed residues, requires pretreatment to enhance their susceptibility to enzymes and microorganisms. This review provides an outlook on bioconversion approaches applicable to different residues of oilseed-bearing plant species. Recent reports on the pretreatment of non-edible oilseed residues for enhancing their bioconversion through either the sugar platform route or anaerobic digestion are critically discussed. This review is based on an exhaustive Web of Science search performed in January–May 2023.
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| 5. |
- García, Ariel, et al.
(författare)
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Dilute sulphuric acid pretreatment and enzymatic hydrolysis of Jatropha curcas fruit shells for ethanol production
- 2014
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Ingår i: Industrial crops and products (Print). - : Elsevier. - 0926-6690 .- 1872-633X. ; 53, s. 148-153
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Jatropha curcas is a promising source of oil for the biodiesel industry, and the shells of its fruits could be considered for ethanol production. In this work, the composition of J. curcas shells is investigated, and the potential of dilute-sulphuric acid pretreatment for improving the enzymatic hydrolysis of cellulose is evaluated. A Box–Behnken experimental design was used for assessing the effect of temperature (110–150 °C), H2SO4 concentration (0.5–2.5%) and pretreatment time (15–45 min) on the formation of sugars during pretreatment and on the enzymatic conversion of cellulose. Cellulose conversions above 80% were achieved both in the separated enzymatic hydrolysis and in the simultaneous saccharification and fermentation of the pretreated materials. Optimal SSF conversions were predicted for pretreatments at low temperature (136 °C) and moderate acid concentrations (1.5%) and reaction time (30 min). The inclusion of an extraction step prior to the pretreatment revealed a further improvement of the enzymatic conversion of cellulose.
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| 6. |
- Ilanidis, Dimitrios, 1986-
(författare)
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Biochemical conversion of biomass : hydrothermal pretreatment, by-product formation, conditioning, enzymatic saccharification, and fermentability
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lignocellulosic residues have great potential as feedstocks for production of bio-based chemicals and fuels. One of the main routes is biochemical conversion, which typically includes pretreatment, enzymatic saccharification, microbial fermentation of sugars, and valorization of hydrolysis lignin. Utilization of a broad variety of lignocellulosic feedstocks and development of more efficient conversion processes are advantageous for making bio-based commodities affordable. Biochemical conversion of lignocellulosic biomass was investigated with the overall aim to understand how variations in pretreatment conditions affected yields, formation of bioconversion inhibitors, enzymatic digestibility of pretreated materials, and fermentability. Experiments included estimation of pseudo-lignin content and quantitation of recently discovered microbial inhibitors, such as formaldehyde and p-benzoquinone. Conditioning of pretreated material to improve the efficiency of reactions with biocatalysts was further investigated.Hydrothermal pretreatment of sugarcane bagasse was investigated by using both autocatalyzed and sulfuric-acid-catalyzed pretreatment and by varying temperature and time in such a way that the severity factor was maintained at one of three predetermined values. For autocatalyzed pretreatments, the enzymatic digestibility of the pretreated solids was directly proportional to the severity. Pretreatment conditions that were just harsh enough to almost quantitatively solubilize hemicelluloses gave the best results. Potential effects of the redox environment during hydrothermal pretreatment were investigated by addition of oxygen gas or nitrogen gas in experiments with sugarcane bagasse and Norway spruce. The investigation demonstrated that gas addition, and especially addition of oxygen gas, can be used to modulate the severity of acidic hydrothermal pretreatment. Hydrothermal pretreatment of wheat straw was investigated to evaluate the impact of pretreatment conditions on newly discovered inhibitors, enzymatic digestibility, and fermentation. An increase of the temperature up to 190 °C in autocatalyzed pretreatment led to high combined glucose and xylose yields; up to ~480 kg/ton (dry weight) raw wheat straw. A correlation between enzymatic digestibility and removal of hemicelluloses was observed. A techno-economical evaluation of several conditioning methods for slurries of steam-pretreated spruce indicated that treatment with sodium sulfite was the most favorable option. Treatments with sulfite and dithionite successfully decreased the concentration of formaldehyde. Results also indicate that increased temperature in conditioning of hydrolysate could to some extent compensate for using lower dosages of sodium dithionite.
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| 7. |
- Martin, Carlos, et al.
(författare)
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Special issue “Pretreatment and Bioconversion of Crop Residues II” : introduction to the collection
- 2024
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Ingår i: Agronomy. - : MDPI. - 2073-4395. ; 14:5
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Bioconversion in biorefineries is a way to valorize residues from agriculture and food processing. Pretreatment is an important step in the bioconversion of lignocellulosic materials, including crop residues. This Special Issue includes nine articles on several pretreatment and bioconversion approaches applied to different agricultural residues and food-processing by-products. The materials addressed in this collection cover straw from wheat, rye, and miscanthus, olive tree pruning residue, almond shells and husks, avocado waste, sweet sorghum bagasse, soybean meal, and residues of non-edible oilseeds.
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