dataesr/scientific-paragraphs-categorization huggingface dataset:
Outside the flammability range, properties are interpolated from solutions obtained at the lean and rich flammability limits and those associated to the pure oxidizer (Y ξ = 0. 0) and fuel (Y ξ = 1. 0) conditions, i. e. , air or fuel at 298 K. Thermophysical and molecular transport properties, e. g. , NASA polynomial coefficients, viscosity, conductivity, and molecular weight  [9]  are subsequently determined from the composition and temperature distributions  [39]. In regard to the strained diffusion flamelet database, equations are formulated in a counter-flowing stream geometry and solved in the physical space rather than in the mixture fraction space  [12]. Flamelets are generated for several values of the strain-rate a = |u Ou F |/d  [40] , smaller than its value at extinction a q. The quantities u O and u F denote the bulk flow velocity of the oxidizer and fuel, respectively, while d refers to the distance between the two nozzles.
The solutions obtained in the physical space are then remapped as functions of the mixture fraction. As shown in the top-right plot of Figure  1 , in addition to pure mixing, both stable and unstable branches of strained diffusion flame solutions are computed  [13, 41]. The strained diffusion flamelet database is in turn remapped as a function of the progress variable  [13]. In this way, flamelet properties of the diffusion flame database will depend on the same set of variables as those retained to parameterize the premixed flamelets, see for instance the ωY c and the CO plots reported in Figures 1. Finally, it is noteworthy that, since it is involved in the premixedness index calculation, see Eq. (  11 ), the norm of the mixture fraction gradient |∇Y ξ | TDF (Y ξ , Y c ) is also tabulated.
Computational methodology For each validation subset, the multiregime flamelet model proposed in the previous section is compared to a reference solution deduced from detailed chemistry (DC) computa-tions. As emphasized above, the multiregime model relies on two distinct databases associated to steady and freely-propagating one-dimensional premixed flames and strained diffusion flamelets. These two building blocks correspond to the two fundamental combustion limits of combustion regimes and the computational results obtained with each of the corresponding databases, i. e. , tabulated premixed flamelets (TPF) and tabulated diffusion flamelets (TDF), will also be considered as references. It is noteworthy that some numerical difficulties are avoided by enforcing the premixedness index ζ PF to zero for values of the progress variable that are smaller than a given threshold.
Similarly, the term n Y ξ • n Y c is removed from Eq. (  8 ) when |∇Y c | falls below a certain limit so as to avoid the singularity. In this case, ζ PF depends only on the ratio of mixture fraction gradients magnitudes. The different modelling approaches have been implemented in the thermophysical module of OpenFOAM-4. 0. It solves the following set of conservation equations for mass, momentum, species mass fractions, and enthalpy: ∂ρ ∂t + ∇ • (ρu) = 0 ( 15 ) ∂ρu ∂t + ∇ • (ρuu) -∇ • (µ∇u) = -∇p (16 ) ∂ρY i ∂t + ∇ • (ρuY i ) -∇ • (D i ∇Y i ) = ωY i ( 17 ) ∂ρh a ∂t + ∇ • (ρuh a ) -∇ • (α∇h a ) = 0 (18) Consistently with Eqs. (  12 ) and (  13 ), and as aforementioned in Section 2. 3, Lewis number effects are not considered (i. e. , D i = D = α). The above system is complemented with the perfect gas equation of state (EoS): p = ρRT M , 1 M = α=N sp α=1 Y α M α ( 19 ) where standard notations have been retained: R is the universal gas constant, M is the molecular weight of the multi-component mixture, and M α , the one of the chemical species α.
The computational results obtained with the proposed index are similar to those issued from the TPF model in case A. Nevertheless, as |∇Y ξ | is increased, the present model, i. e. , the PTF model, does recover some characteristics of the TDF database. Results issued from a blending procedure based on the Takeno premixedness index (TPI) are also included as references. A more quantitative comparison is provided in Fig. 11 , which reports temperature profiles plotted versus mixture fraction conditioned to three values of the normalized progress variable, that is c = {0. 3, 0. 6, 0. 9}. For rich conditions (i. e. , values of Y ξ larger than 0. 055), the  DC results lie between the TPF and the TDF solutions. From a general point of view, the temperature issued from the reference DC simulation is closer to the TPF solution for moderate values of the progress variable c and it approaches the TDF solution as chemical reaction proceeds towards equilibrium (i.
The validation procedure is based on both a priori and a posteriori analyses. In both analyses, the comparisons performed between the results obtained with the proposed flame partitioning and reference detailed chemistry computations lead to a good level of agreement. To conclude, it seems worth emphasizing that this flame index does not require the consideration of any other quantities in addition to those already used to parameterize the flamelets databases, i. e. , Y ξ and Y c , the transport equations of which are solved during the numerical simulations. Existing databases of tabulated premixed and diffusion flamelets can be directly used, and weighted with the premixedness index definition that is introduced in the present study. The model has been applied with a simple definition of the progress variable and leads to an improved level of agreement with the reference DC computations in comparison to the results issued from the consideration of a single flamelet databases (TPF or TDF).
Impulse Excitation method setup The signal for the impulse excitation method was acquired using a microphone MM310 (Microtech Gefell GmbH, Gefell, Germany). This device makes it possible to measure frequencies from 20 Hz to 100 kHz. The data acquisition system was a DEWE-43 coupled with the software Dewesoft X3 (Dewesoft, Trbovlje, Slovenia). Acquisition frequency was set to 200kHz and as a consequence the maximal detectable frequency was 78. 1 kHz. Time domain amplitude signal was converted into a frequency domain signal to measure the resonance frequencies using a fast Fourier transform (FFT) algorithm. A Blackman window with 4069 points was used. The final frequency resolution was25Hz. A complete description of the experimental procedure is given below in the results section.
Numerical method Numerical calculation of the resonance frequencies of tablets was performed using Finite element method (FEM). The FEM modelling was performed using Abaqus® software (Abaqus® Standard 6. 13, Dassault Systèmes, Vélizy-Villacoublay,France). The Lanczos method was used in conjunction with isotropic linear elastic properties as proposed in the literature  (Akseli and Cetinkaya, 2008). This method is already implemented in the Abaqus code.
Young's modulus and Poisson's ratio were obtained for tablets made of several products and manufactured under several pressure points. The values for young's moduli were coherent with published data. Values for Poisson's ratio were low but there are not enough data published on this topic to make a useful comparison. Moreover, the size of the tablet had no influence on the value of the moduli. Finally, by looking at the third frequency of the spectrum and by comparing it with numerical modelling results, we found that differences between measured and calculated values could be a sign of tablet anisotropy. These results are very preliminary, but impulse excitation could be an interesting technique to study the anisotropy in the elastic properties of tablets.
1 K). Samples were tested in a capacitor arrangement, using steel electrodes (15 mm diameter), with a fixed separation (0. 08 mm) maintained by a quartz ring. The applied electric field was 0. 1 V. For measurements at pressures up to 500 MPa, the sample capacitor was placed in a pressure chamber filled with silicone oil. The pressure was measured using a Unipress device with a resolution of 1 MPa. The temperature was controlled within 0. 1 K using a Weiss environmental chamber, with measurements as low as 203. 2 K. To parametrize the dc-conductivity data of [BMIm][BETI] the modified Avramov was applied; the details are presented in SI. The dc-conductivities of the TPIL were reported in ref 19.
1 MPa and T r = T g = 190. 4 K and T r = T g = 240. 8 K for [BMIm][BETI] and TPIL (obtained from differential scanning calorimetry (DSC); see the Methods), respectively. The choice of T r at T g (P r ) is arbitrary; any sufficiently low temperature would suffice. 23 Using the fitted EOS, σ dc is plotted as a function of V (Figure  2A ). 5] [26]  In this work we employed the model-independent procedure  26, 27  (insets a and b of Figure  2A ), according to which T(V) for constant σ dc is plotted double logarithmically versus V, with the slope of the obtained straight line (assuming eq 1 holds) equal to the scaling exponent γ σ. The average γ σ values calculated in this way are 2. 85 ± 0. 05 and 2. 69 ± 0. 20 for IL and PIL, respectively. Scaled plots of σ dc versus TV γ σ are shown in Figure  2C ; a collapse of the data onto a single curve is more evident for IL.
Density Scaling of Entropy. To evaluate the dependence of the total entropy on V, S was calculated using where S r is the entropy at the reference condition and the C P is the molar isobaric heat capacity. C P is a linear function of T and can be obtained at ambient pressure from temperature modulated differential scanning calorimetry (TM-DSC; see the Methods). The obtained relations were C p (T) = 0. 7809T + 458. 85 J mol -1 K -1 for [BMIm][BETI] and C p (T) = 14. 042T + 24210 J mol -1 K -1 for TPIL. Using the PVT data (Table  1 ), we calculated the third term in eq 3 for different isotherms. This was done for both materials over the same intervals of temperature and pressure (ΔT = 140 K, ΔP = 400 MPa). The results for S-S r as a function of V are shown in Figure  3A. To obtain the values of the scaling exponent we employed the method used for the dc-conductivity (insets a and b of Figure  3B ), for values of S-S r from 50 to 300 J mol -1 K -1 with a step of 50 J mol -1 K -1 for [BMIm][BETI], and for TPIL, from 1 to 13 kJ mol -1 K -1 with an increment of 2 kJ mol -1 K -1.
A fresh bottle of methanol was used at each catalytic run. The water concentration was always below 300 ppm (Karl Fischer measurements). As already stated, because of the lack of accurate thermodynamic data for the given operating conditions and the fact that water content has a strong impact on the equilibrium conversion, the conversion at thermodynamic equilibrium was experimentally measured. Conversion measurements were carried out with four different catalysts at 413K and 120 bar for an initial MeOH:CO 2 ratio of 1 and an estimated initial water content of 300 ppm. Conversion was measured after 24 hours of reaction, which is six times longer than the time period used for activity measurements. The conversion at thermodynamic equilibrium (X eq ) was found to be near 0. 8% ±0. 02 (sd) for the four catalysts and is therefore catalyst independent as expected (Fig.
The activity scale is presented as a log scale. FSP: The catalytic data obtained in this study for ceria-zirconia mixed oxides with an equimolar composition or nearly equimolar composition is compared with literature data (Fig. 8 ). We have restricted our comparison to data obtained under three-phase conditions without a water removal system. It is very difficult to compare catalytic activities under the same experimental conditions, as no standard testing protocol exists. Nevertheless, for each set of published data, the highest conversion reached versus ceria-zirconia composition was selected. Activities were calculated from the parameters of the corresponding study (mass of catalyst and reaction duration). Obviously the FSP catalyst is far more active than any other catalyst reported (6 µmol.
Conclusions The present work describes a robust method for measuring catalytic activity for DMC synthesis from methanol and CO 2 far from equilibrium conditions. This method made it possible to rank the activity of more than 60 catalysts which, to the best of our knowledge, is the largest consistent dataset yet reported. Different synthesis methods and compositions were tested. By selecting the most active composition of ceria-zirconia samples and further exploring different synthesis approaches, we found that the synthesis of mixed ceria-zirconia oxides by flame spray pyrolysis yielded the most active catalysts reported so far. We do not claim that other catalysts with higher activity could not exist, as the screening was of moderate size. On the contrary, we believe that better catalysts may exist with different Ce-Zr ratios, in particular Ce-rich compositions or solids that have undergone an optimized thermal treatment.
ACKNOWLEDGMENT The authors of Liège thank the  Fonds National de la Recherche Scientifique (FNRS)  and the  Fonds Wetenschappelijk Onderzoek -Vlaanderen (FWO)  for funding the  EOS  project  n°O019618F  ( ID EOS: 30902231 ) and the  FNRS  in the frame of the  FRIA  project of C.
X-ray cristallography Data collections for crystals of 1a, 3a, 4a, 8a, 9a were performed at the X-ray diffraction beamline (XRD1) of the Elettra Synchrotron of Trieste (Italy) equipped with a Pilatus 2 M image plate detector. Collection temperature was 100 K (nitrogen stream supplied through an Oxford Cryostream 700); the wavelength of the monochromatic X-ray beam was 0. 700 angstrom and the diffractograms were obtained with the rotating crystal method. The crystals were dipped in Nparatone and mounted on the goniometer head with a nylon loop. The diffraction data were indexed, integrated and scaled using the XDS code [3]. The structures were solved by the dual space algorithm implemented in the SHELXT code [4]. Fourier analysis and refinement were performed by the full-matrix least-squares methods based on F 2 implemented in SHELXL [5].
The Shelxle program was used for modeling [6]. Anisotropic thermal motion was allowed for all non-hydrogen atoms. Hydrogen atoms were placed at calculated positions with isotropic factors U = 1. 2 × Ueq, where Ueq is the equivalent isotropic thermal factor of the bonded non hydrogen atom. Table  S1. Most significant distances and angles for complexes 1a, 2a, 3a, 4a, 8a, 9a.
Acknowledgements We would like to express our sincere gratitude to  PSL Research University  for their support under the  program 'Investissements d'Avenir ' launched by the  French Government  and implemented by the  French National Research Agency (ANR)  with the reference  ANR-10-IDEX-0001-02 PSL. plied Mechanics, Stanford, 1968  Springer-Verlag ,  Berlin ,  382. Tomé, M. F. , Araujo, M. T. , Evans, J. , Mckee, S. , 2019. Numerical solution of the giesekus model for incompressible free surface flows without solvent viscosity. Journal of Non-Newtonian Fluid Mechanics 263,  104-119. Valette,  R. , Hachem ,  E. , Khalloufi ,  M. , Pereira , A. S. , Mackley, M. R. , Butler, S. A. , 2019. The effect of viscosity, yield stress, and surface tension on the deformation and breakup profiles of fluid filaments stretched at very high velocities.
g. NH 2 and NO). At the same time, the experimental data under these operating conditions in support of a proper model development are still very limited. Starting from this scenario, the aim of this work is filling the void of knowledge still remaining in the kinetic mechanisms involved in the oxidation of ammonia, with a focus on the critical conditions previously mentioned, and scarcely explored so far. To this purpose, new experimental measurements were performed in a jet-stirred reactor (JSR) and a flow reactor (FR), such as to explore the low-and intermediate-temperature oxidation of ammonia with high dilution levels. At the same time, the critical rate constants involved in the ammonia combustion mechanism were systematically evaluated through a first-principles methodology. In particular, NH 3 decomposition, as well as H-abstractions by O 2 , H, O, OH and HO 2 , and the dissociation of the HNO intermediate are discussed.
To confirm this, the following protocol was followed: 1. Ammonia pyrolysis was first performed in a non-recrystallized alumina tube, in order to have a reference for comparison. 2. Then, the tube wall was coated with carbonaceous material by carrying out methane pyrolysis in the non-recrystallized alumina tube. 3. After coating, ammonia pyrolysis was repeated, and a significant shift of the reactivity of ∼500 K towards lower temperatures was observed. As a result, the tube was replaced and recrystallized alumina was adopted (with a higher purity than alumina). This resulted in a global shift of the reactivity of ∼100 K towards higher temperatures when compared to the data obtained with the non-coated, non-recrystallized alumina first tube, and provided data consistent with model predictions.
Two intense lines were used to quantify ammonia with a good sensitivity: 6641. 33 and 6642. 57 cm -1. Cross sections needed for the calibrations were measured using data recorded under unreactive conditions. The relative uncertainty in NH 3 mole fraction detected by CRDS is ±10%. iv. A dual channel NO x chemiluminescence analyzer (Thermo Scientific Model 42i) was used for the detection of NO and NO 2 (but no NO 2 was detected in these experiments). The detection is based on the conversion of NO (with ozone) to an excited state of NO 2 that emits a chemiluminescent light when dropping to the ground state. On the first channel, the detection of nitric oxide is performed in a direct and independent way, whereas the second channel is dedicated to the measure of the total NO x concentration. In this second channel, the sampled gas passes over a heated catalyst transforming nitrogen oxides to nitric oxide, NO, which is detected by chemiluminescence as in the first channel.
Theoretical methodologies The rate constants of a specific set of reactions were determined theoretically. They were identified on the basis of a combined uncertainty and sensitivity analysis with respect to the explored experimental conditions as well as on the availability of previous experimental/theoretical studies for each of them. The adopted computational methodology is the ab initio transition state theory based master equation (ME) approach (AITSTME) that was recently implemented in the EStokTP software. 44 Electronic structure calculations for abstraction reactions were performed determining structures and vibrational frequencies at the M06-2X/aug-cc-pVTZ level and energies at the unrestricted CCSD(T)/aug-cc-pVTZ level, corrected for basis set size effect with the change of density fitted (DF) MP2 energies computed using aug-cc-pVQZ and aug-cc-pVTZ basis sets.
Kinetic modeling The development of the kinetic model was performed by following a hierarchical and modular approach, as originally conceived in the CRECK kinetic framework. 48 The core H 2 /O 2 mechanism was adopted after the work of Metcalfe et al. 49  The NO x module, foundation of the whole NH 3 mechanism, was taken from the work of Song et al. ,  38  on turn based on the works of Faravelli, Frassoldati et al. 50, 51  The major updates were performed on HONO/HNO 2 chemistry, after the recent work of Chen et al. 52  For all the species, the thermodynamic properties were systematically updated using the database of Burcat and Ruscic. 53 monia submechanism was added on top of the NO x module, and the critical reactions are summarized in Table  1. The parameters of reactions R1 to R6 and R28 were calculated through the fitting of the temperature-dependent rates obtained from the related theoretical calculations via a modified-Arrhenius format  =   [-  /()].
Ignition delay times The prediction ability of the kinetic model was assessed for the measurement of ignition delay times (IDTs) in a wide range of operating conditions, i. e. 1000 K < T c < 2500 K and 1. 4 atm < P c < 60 atm, with different dilution levels. Due to the low reactivity of ammonia and longer IDTs, the presence of non-ideal, dynamic effects must be taken into account in the simulation of experimental data at both intermediate-and low-temperature conditions. Therefore, for the intermediate-temperature shock tube (ST) measurements,  32  the experimental pressure profile of the single experiments was converted into volume profile, starting from the arrival time of the reflected shock wave until the time point equal to 90% of the measured IDT, after which the volume was kept constant.
Constrainedvolume 0D simulations were then performed using the obtained profile. For the rapid compression machine (RCM) simulations,  34  the whole recorded pressure profile was converted into volume profile and used to perform constrained-volume 0D simulations. High-temperature datasets were instead simulated as homogeneous constant-volume 0D simulations. Figure  14  shows the results of 3 different equivalence ratios at various pressures. A satisfactory agreement can be observed for the high-temperature data of Mathieu and Petersen 27 in the whole operating range, with a slight underprediction under lean conditions. At intermediate temperatures (1100 K <   < 1600 K), the mechanism well reproduces the non-linear behavior of experimental data, due to pre-ignition effects. More significant deviations are can be seen at Φ = 2 and   = 40 bar.
60  (used in this work), differing from each other by a factor or ∼1. 4 at 1000-2000 K. R23 also had a boosting effect on the production of NO at intermediate and high-temperatures in flow reactor (Figures  11  and 13 ), as already pointed out by Glarborg et al. in their review. 31 Therefore, considering the role of R23 within the current mechanism, the accuracy of those two datasets is someway competitive. A more complete validation of the kinetic mechanism in terms of laminar flame speed predictions, with different oxidizer compositions can be found in the Supplementary Material.
Conclusions The renewed interest raised by NH 3 combustion in the recent years has made available a significant amount of experimental data, characterizing its reactivity in a wide range of operating conditions. Yet, a comprehensive understanding of its kinetic behavior is still an open challenge, especially at lowtemperature ( < 1200 K) and under diluted conditions, on which the combustion community is devoting a significant effort because of the potentially lower NOx emissions. In this work, this topic was addressed through a combined experimental and theoretical approach, able to shed light on the kinetic behavior of ammonia affecting low-temperature, diluted conditions. New experimental data were collected in jet-stirred and flow reactors at pressure close to atmospheric, in such a way to cover the whole range of temperatures (500-2000 K).
Acknowledgements This work has been carried out under the financial support of the  IMPROOF  project ( H2020-IND-CE-2016-17/H2020-SPIRE-S016 ) within the  European Union   Horizon 2020 research and innovation program  (grant agreement no. 723706 ), and of the  COST Action   CM1404  " Chemistry of smart energy carriers and technologies ". The authors are also grateful to  Prof. Christine Rousselle  ( Université d'Orléans ) for the fruitful discussions.
The diameter of cone-and-plate geometry is 60 mm, the angle 2 °C. The slurry viscosity was measured based on a shear rate in a range of 0. 05-1500 s -1 at 20 °C. Zeta potential of the slurry as a function of pH was measured on a ZetaPALS instrument (Brookhaven) by the use of an electrophoretic technique. The mobility of charged particles can be determined via this technique by the phase analysis light scattering (PALS). Thermogravimetric analysis (TGA) of the γ-Al 2 O 3 slurry was performed on a PerkinElmer TGA 4000 thermogravimetric analyzer. The slurry was heated up in nitrogen from 30 °C to 1000 °C (at 10 °C min -1 ). Data were recorded by Pyris thermal analysis software. Scanning electron microscopy (SEM) was performed on an XL30 ESEM (Philips) operating at 20 keV, to characterize the smoothness and thickness of the washcoated γ-Al 2 O 3 layer on the microchannel.