405 research outputs found

    The entropy puzzle and the quark combination model

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    We use two available methods, the Duhem-Gibbs relation and the entropy formula in terms of particle phase space distributions, to calculate the entropy in a quark combination model. The entropy of the system extracted from the Duhem-Gibbs relation is found to increase in hadronization if the average temperature of the hadronic phase is lower than that of the quark phase. The increase of the entropy can also be confirmed from the entropy formula if the volume of the hadronic phase is larger than 2.5-3.0 times that of the quark phase. So whether the entropy increases or decreases during combination depends on the temperature before and after combination and on how much expansion the system undergoes during combination. The current study provides an example to shed light on the entropy issue in the quark combination model.Comment: RevTex 4, 4 pages, 2 tables, 4 figures, discussions and references added, to appear in PR

    Production rates for hadrons, pentaquarks ╬ś+\Theta ^+ and ╬śÔłŚ++\Theta ^{*++}, and di-baryon (╬ę╬ę)0+(\Omega\Omega)_{0^{+}} in relativistic heavy ion collisions by a quark combination model

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    The hadron production in relativistic heavy ion collisions is well described by the quark combination model. The mixed ratios for various hadrons and the transverse momentum spectra for long-life hadrons are predicted and agree with recent RHIC data. The production rates for the pentaquarks ╬ś+\Theta ^+, ╬śÔłŚ++\Theta ^{*++} and the di-baryon (╬ę╬ę)0+(\Omega\Omega)_{0^{+}} are estimated, neglecting the effect from the transition amplitude for constituent quarks to form an exotic state.Comment: The difference between our model and other combination models is clarified. The scaled transverse momentum spectra for pions, kaons and protoms at both 130 AGeV and 200 AGeV are given, replacing the previous results in transverse momentum spectr

    Assessment of the spatial and temporal variations of water quality for agricultural lands with crop rotation in China by using a HYPE model

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    Many water quality models have been successfully used worldwide to predict nutrient losses from anthropogenically impacted catchments, but hydrological and nutrient simulations with little data are difficult considering the transfer of model parameters and complication of model calibration and validation. This study aims (i) to assess the performance capabilities of a new and relatively more advantageous model-hydrological predictions for the environment (HYPE) to simulate stream flow and nutrient load in ungauged agricultural areas by using a multi-site and multi-objective parameter calibration method and (ii) to investigate the temporal and spatial variations of total nitrogen (TN) and total phosphorous (TP) concentrations and loads with crop rotation using the model for the first time. A parameter estimation tool (PEST) was used to calibrate parameters, which shows that the parameters related to the effective soil porosity were most sensitive to hydrological modeling. N balance was largely controlled by soil denitrification processes, whereas P balance was influenced by the sedimentation rate and production/decay of P in rivers and lakes. The model reproduced the temporal and spatial variations of discharge and TN/TP relatively well in both calibration (2006ÔÇô2008) and validation (2009ÔÇô2010) periods. The lowest NSEs (Nash-Suttclife Efficiency) of discharge, daily TN load, and daily TP load were 0.74, 0.51, and 0.54, respectively. The seasonal variations of daily TN concentrations in the entire simulation period were insufficient, indicated that crop rotation changed the timing and amount of N output. Monthly TN and TP simulation yields revealed that nutrient outputs were abundant in summer in terms of the corresponding discharge. The area-weighted TN and TP load annual yields in five years showed that nutrient loads were extremely high along Hong and Ru rivers, especially in agricultural lands

    Proizvodnja polinezasićenih masnih kiselina s pomoću plijesni Mucor recurvus sp. upotrebom melase šećerne trske kao izvora ugljika

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    Sugarcane molasses is rich in nutriments and vitamins. It may be used as the carbon source for the production of polyunsaturated fatty acids (PUFA) by Mucor recurvus sp. Using sugarcane molasses, the effects of fermentation parameters and media components on polyunsaturated fatty acid production through both linear and orthogonal array experiments were investigated. The best fermentation conditions for PUFA production were found as follows: 15 % sugarcane molasses, pH=6.0, 28 ┬░C, 5 days, 160 rpm. It was also found that molasses and urea enhanced PUFA production with the optimal carbon to nitrogen (C/N) ratio of 35. Under the most favourable conditions, the total lipid content at 7.13 g/L and PUFA up to 5.74 g/L including (0.82┬▒0.05) g/L of linolenic acid (LA), (1.35┬▒0.02) g/L of ╬│-linolenic acid (GLA), (0.17┬▒0.06) g/L of ╬▒-linolenic acid (ALA), (0.57┬▒0.06) g/L of arachidonic acid (ARA), (0.46┬▒0.07) g/L of eicosapentaenoic acid (EPA) and (0.34┬▒0.08) g/L of docosahexaenoic acid (DHA) were obtained. Our study suggests that sugarcane molasses is a superior alternative carbon source for industrial PUFA production.Melasa ┼íe─çerne trske je bogata hranjivim tvarima i vitaminima. Upotrebljava se kao izvor ugljika za proizvodnju polinezasi─çenih masnih kiselina s pomo─çu plijesni Mucor recurvus sp. Linearnom i ortogonalnom metodom istra┼żen je utjecaj uvjeta fermentacije i sastojaka podloge, uz dodatak melase ┼íe─çerne trske, na proizvodnju polinezasi─çenih masnih kiselina. Najbolji uvjeti fermentacije za proizvodnju polinezasi─çenih masnih kiselina bili su: 15 % melase ┼íe─çerne trske; pH=6,0; 28 ┬░C; 5 dana i 160 rpm. Tako─Ĺer je utvr─Ĺeno da dodatak melase i uree pove─çava proizvodnju pri optimalnom omjeru ugljika i du┼íika C/N=35. Pri optimalnim uvjetima proizvedeno je ukupno 7,13 g/L lipida i 5,74 g/L polinezasi─çenih masnih kiselina, od toga (0,82┬▒0,05) g/L linolenske kiseline, (1,35┬▒0,02) g/L ╬│-linolenske kiseline, (0,17┬▒0,06) g/L ╬▒-linolenske kiseline, (0,57┬▒0,06) g/L arahidonske kiseline, (0,46┬▒0,07) g/L eikosapentenoi─Źne kiseline i (0,34┬▒0,08) g/L dokosaheksaenoi─Źne kiseline. Ovo je istra┼żivanje pokazalo da je melasa ┼íe─çerne trske najbolji alternativni izvor ugljika za industrijsku proizvodnju polinezasi─çenih masnih kiselina

    Proizvodnja polinezasićenih masnih kiselina s pomoću plijesni Mucor recurvus sp. upotrebom melase šećerne trske kao izvora ugljika

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    Sugarcane molasses is rich in nutriments and vitamins. It may be used as the carbon source for the production of polyunsaturated fatty acids (PUFA) by Mucor recurvus sp. Using sugarcane molasses, the effects of fermentation parameters and media components on polyunsaturated fatty acid production through both linear and orthogonal array experiments were investigated. The best fermentation conditions for PUFA production were found as follows: 15 % sugarcane molasses, pH=6.0, 28 ┬░C, 5 days, 160 rpm. It was also found that molasses and urea enhanced PUFA production with the optimal carbon to nitrogen (C/N) ratio of 35. Under the most favourable conditions, the total lipid content at 7.13 g/L and PUFA up to 5.74 g/L including (0.82┬▒0.05) g/L of linolenic acid (LA), (1.35┬▒0.02) g/L of ╬│-linolenic acid (GLA), (0.17┬▒0.06) g/L of ╬▒-linolenic acid (ALA), (0.57┬▒0.06) g/L of arachidonic acid (ARA), (0.46┬▒0.07) g/L of eicosapentaenoic acid (EPA) and (0.34┬▒0.08) g/L of docosahexaenoic acid (DHA) were obtained. Our study suggests that sugarcane molasses is a superior alternative carbon source for industrial PUFA production.Melasa ┼íe─çerne trske je bogata hranjivim tvarima i vitaminima. Upotrebljava se kao izvor ugljika za proizvodnju polinezasi─çenih masnih kiselina s pomo─çu plijesni Mucor recurvus sp. Linearnom i ortogonalnom metodom istra┼żen je utjecaj uvjeta fermentacije i sastojaka podloge, uz dodatak melase ┼íe─çerne trske, na proizvodnju polinezasi─çenih masnih kiselina. Najbolji uvjeti fermentacije za proizvodnju polinezasi─çenih masnih kiselina bili su: 15 % melase ┼íe─çerne trske; pH=6,0; 28 ┬░C; 5 dana i 160 rpm. Tako─Ĺer je utvr─Ĺeno da dodatak melase i uree pove─çava proizvodnju pri optimalnom omjeru ugljika i du┼íika C/N=35. Pri optimalnim uvjetima proizvedeno je ukupno 7,13 g/L lipida i 5,74 g/L polinezasi─çenih masnih kiselina, od toga (0,82┬▒0,05) g/L linolenske kiseline, (1,35┬▒0,02) g/L ╬│-linolenske kiseline, (0,17┬▒0,06) g/L ╬▒-linolenske kiseline, (0,57┬▒0,06) g/L arahidonske kiseline, (0,46┬▒0,07) g/L eikosapentenoi─Źne kiseline i (0,34┬▒0,08) g/L dokosaheksaenoi─Źne kiseline. Ovo je istra┼żivanje pokazalo da je melasa ┼íe─çerne trske najbolji alternativni izvor ugljika za industrijsku proizvodnju polinezasi─çenih masnih kiselina

    Second-harmonic generation via double topological valley-Hall kink modes in all-dielectric photonic crystals

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    Nonlinear topological photonics, which explores topics common to the fields of topological phases and nonlinear optics, is expected to open up a new paradigm in topological photonics. Here, we demonstrate second-harmonic generation via nonlinear interaction of double topological valley-Hall kink modes in all-dielectric photonic crystals. We first show that two topological frequency bandgaps can be created around a pair of frequencies, ¤ë0\omega_0 and 2¤ë02\omega_0, by gapping out the corresponding Dirac points in two-dimensional honeycomb photonic crystals. Valley-Hall kink modes along a kink-type domain wall interface between two photonic crystals placed together in a mirror-symmetric manner are generated within the two frequency bandgaps. Importantly, through full-wave simulations and mode dispersion analysis, we demonstrate that tunable, bi-directional phase-matched second-harmonic generation via nonlinear interaction of the valley-Hall kink modes within the two frequency bandgaps could be achieved. Our work opens up new avenues towards topologically protected nonlinear frequency mixing in optics using all-dielectric materials.Comment: 5 pages, 4 figure

    Production of Strange and Charm Hadrons in Pb+Pb Collisions at sNN=\sqrt{s_{NN}}= 5.02 TeV

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    Using a quark combination model with the equal-velocity combination approximation, we study the production of hadrons with strangeness and charm flavor quantum numbers in Pb+Pb collisions at sNN=\sqrt{s_{NN}}=5.02 TeV. We present analytical expressions and numerical results for these hadrons' transverse momentum spectra and yield ratios. Our numerical results agree well with the experimental data available. The features of strange and charm hadron production in the quark--gluon plasma at the early stage of heavy ion collisions are also discussed.Comment: 12 pages, 9 figure
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