Values Of Cross Sections Research Articles

Effect of carbonaceous components of biodiesel combustion particles on optical properties

This paper studies the influence of carbonaceous components on the optical properties of particulate matter (PM) in biodiesel combustion by conducting a bench test on an electronically controlled high-pressure common-rail diesel engine. In addition, the PM produced by the combustion of diesel oil, soybean oil methyl ester (SME), waste edible oil methyl ester (WME), and palm oil methyl ester (PME) was collected. The carbonaceous composition and optical properties of diesel and three biodiesel particulates were then analyzed. The obtained results showed that the ratio of organic carbon (OC) to total carbon (TC) in diesel PM was 0.25 and the ratio of OC/EC was 0.33. The OC to TC ratio of biodiesel PM was significantly greater than that of diesel PM, ranging between 0.59 and 0.65, with OC/EC values in the range of 1.44–1.86. The mass absorption cross-section (MAC) values of three kinds of biodiesel particles were all higher than those of diesel particles. When the incident laser wavelength increased, the difference of MAC values among four kinds of fuel particles gradually decreased. The MAC values of all the three biodiesel particles were higher than those of the diesel particles, and the difference between the MAC values of the four fuel particles gradually decreased with the increase of the incident laser wavelength. Afterwards, the “shell-core” model of particles was developed with 80 nm EC sphere as the core. At the two refractive indices, the scattering cross section, absorption cross section, and extinction cross section of the particles decrease with the increase of the incident light wavelength, and the scattering cross section, absorption cross section, and extinction cross section of the particles increase with the increase of the OC coating thickness.

Native Mass Spectrometry and Collision-Induced Unfolding of Laser-Ablated Proteins.

Infrared laser ablation sample transfer (LAST) was used to collect samples from solid surfaces for mass spectrometry under native spray conditions. Native mass spectrometry was utilized to probe the charge states and collision-induced unfolding (CIU) characteristics of bovine serum albumin (BSA), bovine hemoglobin (BHb), and jack-bean concanavalin A (ConA) via direct injection electrospray, after liquid extraction surface sampling, and after LAST. Each protein was deposited from solution on solid surfaces and laser-ablated for off-line analysis or sampled for online analysis. It was found that the protein ion gas-phase charge-state distributions were comparable for direct infusion, liquid extraction, and laser ablation experiments. Moreover, calculated average collision cross section (CCS) values from direct injection, liquid extraction, and laser ablation experiments were consistent with previously reported literature values. Additionally, an equivalent number of mobility features and conformational turnovers were identified from unfolding pathways from all three methods for all charge states of each protein analyzed in this work. The presented work suggests that laser ablation yields intact proteins (BSA, BHb, and ConA), is compatible with native mass spectrometry, and could be suitable for spatially resolved interrogation of unfolding pathways of proteins.

Mutual coupling and RCS reduction of MIMO dielectric resonator antenna for S-band applications

This paper designs and analyses a two-port dielectric resonator-based multiple-input, multiple-output (MIMO) antenna. A tilted L-shaped aperture is used to excite the cylindrical-shaped ceramic. This type of feeding structure produces the circularly polarized (CP) waves and HEM11δ mode inside the ceramic. The proposed antenna shows two main features: (i) the polarization diversity concept reduces the isolation level by 15 dB; (ii) integration of frequency-selective surface (FSS) reduces the radar cross-section (RCS) value by an amount of 7.5 dBsm within the operating band. The fabricated structure confirms the working band of the proposed antenna from 2.8 to 3.2 GHz. 3-dB axial ratios is achieved between 2.8 and 3.05 GHz. The proposed antenna's good diversity parameter value and stable radiation characteristics make it applicable for S-band wireless applications

Linear polarization on radar cross section measurement for tank miniature

The use of radar technology, especially for the interests of state defense and security, has become the focus of development launched by the government of Indonesia. Equipment and vehicles in the defense and security sector are the top priority to be detected using radar technology. When a radar transmitter transmits its signal towards a target, some part of the signal will bounce in all directions or scattering, including to the receiver and some will be absorbed by the radar target. The radar target is assumed to have a small size, with the aim of focusing more on the beamwidth of the radar transmitting antenna to the target. This research has a focus on measuring radar targets in the form of defense equipment in the form of tanks made in miniature which are smaller than their original forms. The selected antenna polarization uses linear polarization with vertical and horizontal types. Each polarization will be compared with the value of the radar cross section (RCS) in the combination of the same polarization and different polarization. The measurement results show that the largest RCS value is obtained at an angle of 200° by 13 with a combination of Horizontal-Horizontal polarization and the smallest RCS value is obtained at an angle of 50° by -4 with a combination of Horizontal-Vertical polarization. With the results of these measurements, it can be concluded that the measurement of RCS for defense and security equipment can be carried out by measuring the miniature of the defense and security equipment

An analysis of crystallographic texture and residual stresses of aluminium alloy RSA-501 after selected processes of twist extrusion (TE)

This study presents the residual stress analysis for the twist extrusion (TE) process after the experiment and numerical simulation and the analysis of the crystallographic texture changes and changes in hardness before and after the TE process for an RSA-501 aluminium alloy (Al; Mg5%; Mn1.5%; Sc0.8%; Zr0.4%).Crystallographic textures were obtained with the PANAlytical Empyrean X-ray diffractometer. The stresses were measured by applying the X-ray method with the use of using the PROTO iXRD diffractometer.The use of severe plastic deformation processes in the mass of the material leads to a significant change difference in the stress distribution in the workpiece and a change in texture compared to the reference material. The stress distribution in the sample cross-section and stress values varied and depended on the stage of the twisting process to which the surface was subjected. The highest stress (about 600 MPa) appears at the peaks of the front surface when exiting the twist area die TE. Higher stress values at the edges of the specimen are caused by friction (deformation) of the material against the die surface. The TE process strengthened the highest crystallographic texture background level was 49%.The conducted tests and the obtained results allow the determination of the process parameters and critical areas of the sample by carrying out a numerical simulation.Microhardness increases due to the TE process and the largest values were observed at the edges. This phenomenon is confirmed by the numerical simulation results presented in this paper.

Development and validation of an iodine plasma model for gridded ion thrusters

Iodine is emerging as an attractive alternative propellant to xenon for several electric propulsion technologies due to its significantly lower cost and its ability to be stored unpressurized as a solid. Because of the more complex reaction processes and energy-loss channels in iodine plasmas however, as well as the historical lack of reliable collision cross-section data, the development of accurate theoretical and numerical models has been hindered. Using recently calculated theoretical cross-sections, we present an iodine plasma model and perform a comparison with experimental data obtained from an iodine-fuelled gridded ion thruster. The model is in reasonable agreement with experimental measurements of the ion beam current, propellant mass utilization efficiency, and ion beam composition, and is able to quantitatively and qualitatively reproduce system behaviour as the input mass flow rate and RF power are varied. In addition, both the model and experiment show that the use of iodine can lead to a performance enhancement when compared with xenon. This occurs because of the combination of different iodine reaction processes, collision cross-section values, and inelastic energy thresholds which result in lower collisional energy losses, as well as an increased antenna-plasma power transfer efficiency for thrusters using a radio-frequency inductive coil.

Comprehensive study on structure, shielding properties of Ga-In-Sn-Bi-Zn alloys: potential use for low energy radiation

Low-melting point Ga-In-Sn-Bi-Zn alloys were prepared using a vacuum melting technique as a novel radiation shielding material. To evaluate the interaction between alloys and photons in the energy range of 1–10000 keV, the WinXCom and Phy-X procedures are used to determine the shielding parameters for the Ga-In-Sn-Bi-Zn alloys, such as the mass attenuation coefficient, linear attenuation coefficient, half-value layer, tenth-value layer, mean free path, effective atomic number. Simultaneously, the energy absorption and exposure buildup factors, fast neutron removal cross section values is also calculated and the comparative lead equivalent (M) and weight reduction over lead for the alloy samples are compared. It is observed that the Ga2In2Sn2Bi3Zn1 alloy have exhibit superior comprehensive radiation attenuation, with a weight reduction of 2.948% compared to lead for the same shielding performance in the 30–90 keV range. After being irradiated by 40 keV He + irradiation system for 120 h, the phase structure of Ga2In2Sn2Bi3Zn1 alloy remained unchanged and that it shows excellent radiation tolerance. Combined with field emission scanning electron microscopy, x-ray diffraction, differential scanning calorimetry and thermogravimetric analysis results indicate that Ga2In2Sn2Bi3Zn1 is a eutectic alloy with a five-phase complex-regular structure and a melting point of 66.95 °C. The alloy exhibits excellent fluid compliance in the molten state when blended with polymers to prepare composites. The alloy filler is uniformly and continuously distributed in the polymer matrix, which ensures the reliability of the radiation shielding properties of the composites.

Prediction of Retention Time and Collision Cross Section (CCSH+, CCSH-, and CCSNa+) of Emerging Contaminants Using Multiple Adaptive Regression Splines.

Ultra-high performance liquid chromatography coupled to ion mobility separation and high-resolution mass spectrometry instruments have proven very valuable for screening of emerging contaminants in the aquatic environment. However, when applying suspect or nontarget approaches (i.e., when no reference standards are available), there is no information on retention time (RT) and collision cross-section (CCS) values to facilitate identification. In silico prediction tools of RT and CCS can therefore be of great utility to decrease the number of candidates to investigate. In this work, Multiple Adaptive Regression Splines (MARS) were evaluated for the prediction of both RT and CCS. MARS prediction models were developed and validated using a database of 477 protonated molecules, 169 deprotonated molecules, and 249 sodium adducts. Multivariate and univariate models were evaluated showing a better fit for univariate models to the experimental data. The RT model (R2 = 0.855) showed a deviation between predicted and experimental data of ±2.32 min (95% confidence intervals). The deviation observed for CCS data of protonated molecules using the CCSH model (R2 = 0.966) was ±4.05% with 95% confidence intervals. The CCSH model was also tested for the prediction of deprotonated molecules, resulting in deviations below ±5.86% for the 95% of the cases. Finally, a third model was developed for sodium adducts (CCSNa, R2 = 0.954) with deviation below ±5.25% for 95% of the cases. The developed models have been incorporated in an open-access and user-friendly online platform which represents a great advantage for third-party research laboratories for predicting both RT and CCS data.

Dicyanomethylene-functionalized s-indacene-based D-π-A-π-D dyes exhibiting large near-infrared two-photon absorption cross-section

A series of centrosymmetric chromophores with D-π-A-π-D molecular architecture has been synthesized and characterized with respect to their third-order nonlinear optical (NLO) properties. The investigated compounds feature novel central electron acceptor fragments composed of derivatives of s-indacene-1,3,5,7(2H,6H)-tetraone (Janus dione), in which the carbonyls have been substituted by either two or four dicyanomethylene groups. Due to the increased electron acceptor strength, up to twofold increase in two-photon absorption (2 PA) cross-section is observed for the dyes in comparison to the structural analogues based on the parent compound. The best performing dye exhibits intensive 2 PA absorption band in 1000–1300 nm range with a peak cross-section value of 11,000 GM. Optical limiting was successfully demonstrated using the compound, marking the presented chemical design as a promising direction for optical power-limiting applications in the important near-infrared (NIR) spectral region.Electronic Supplementary Information (ESI) available: experimental procedures, results of quantum chemical calculations, NMR spectra.

Enhancing spectral quality in complex environmental matrices: Supporting suspect and non-target screening in zebra mussels with ion mobility

Identification of bioaccumulating contaminants of emerging concern (CECs) via suspect and non-target screening remains a challenging task. In this study, ion mobility separation with high-resolution mass spectrometry (IM-HRMS) was used to investigate the effects of drift time (DT) alignment on spectrum quality and peak annotation for screening of CECs in complex sample matrices using data independent acquisition (DIA). Data treatment approaches (Binary Sample Comparison) and prioritisation strategies (Halogen Match, co-occurrence of features in biota and the water phase) were explored in a case study on zebra mussel (Dreissena polymorpha) in Lake Mälaren, Sweden’s largest drinking water reservoir. DT alignment evidently improved the fragment spectrum quality by increasing the similarity score to reference spectra from on average (±standard deviation) 0.33 ± 0.31 to 0.64 ± 0.30 points, thus positively influencing structure elucidation efforts. Thirty-two features were tentatively identified at confidence level 3 or higher using MetFrag coupled with the new PubChemLite database, which included predicted collision cross-section values from CCSbase. The implementation of predicted mobility data was found to support compound annotation. This study illustrates a quantitative assessment of the benefits of IM-HRMS on spectral quality, which will enhance the performance of future screening studies of CECs in complex environmental matrices.

(d, 3n) Reaction cross-section calculation of some reactor materials

Nuclear reactions with charged particles have applications in many fields such as radioisotope production, industrial applications, astrophysics, etc. Therefore, examining the excitation functions performed and obtained by the activation technique is also important for understanding the nature of nuclear reactions. Also, it is especially necessary to study these reactions to estimate the effects of radiation damage on the fusion structural materials used in the construction of the first walls and core of the reactor. In this study, cross-section data have been calculated theoretically to 45Sc (d, 3n)44Ti, 63Cu (d, 3n)62Zn, 89Y (d, 3n)88Zr, and 100Mo (d, 3n)99Tc reactions in the range of 1–50 MeV energy via ALICE/ASH, TALYS 1.95 and Empire 3.2.2 nuclear reaction codes. Optical Model Parameters (OMP) calculation for deuteron-induced reaction results has been performed via TALYS 1.95 code and the calculated cross-section values are reproduced well. Also, empirically developed (d, 3n) cross section formula (Kavun, 2020) calculations have been performed at 20 MeV energy. Finally, experimental EXFOR data was compared with all results and were found to be compatible with each other.

Trapping Alkali Halide Cluster Ions Inside the Cucurbit[7]uril Cavity.

In this study, the distinctive behavior of cucurbit[n]uril (CB[n]), which captures a variety of alkali halide clusters inside the cavity during the droplet evaporation, has been investigated by using ion mobility spectrometry-mass spectrometry. Complexes of CB[7] with various alkali chloride cluster cations or anions generated during the electrospray ionization were studied, and their collision cross-section (CCS) values were obtained to determine whether these clusters were trapped inside the cavity or not. It was found that the clusters smaller than a specific critical size were trapped inside the CB[7] cavity in the gas phase, although trapping of alkali halide clusters at the given concentration is supposed to be unfavorable in solution. We suggest that the rapid solvent evaporation rapidly increases ion concentrations and subsequently forms alkali-chloride contact ion pairs; therefore, it may provide a specific environment to enable the formation of the inclusion complexes.

Differential Cross-section Measurements for 3He Elastic Scattering on 16O and 27Al

In the present work measurements to determine the differential cross section values for the elastic scattering of 3He on 16O and 27Al were carried out at the Ruđer Bošković Institute (RBI) Tandem Accelerator Facility in Zagreb, Croatia, covering the E3He,lab=3500-5600 keV energy range, using four Silicon Surface Barrier (SSB) detectors positioned at the backscattering angles of 130°, 145°, 157.7° and 165ο. The target was constructed at the facility and was comprised of a thin, self-supporting aluminum foil, upon which a thin layer of natB (isotopic ratio: 11B 80.1%, 10B 19.9%), along with 12C, 14N, 16O, was deposited using the sputtering technique. In addition, an ultra-thin layer of 197Au was evaporated on top for wear protection and normalization purposes.

Rapid structural characterization of human milk oligosaccharides and distinction of their isomers using trapped ion mobility spectrometry time-of-flight mass spectrometry.

Oligosaccharides have multiple functions essential for health. Derived from the condensation of two to several monosaccharides, they are structurally diverse with many co-occurring structural isomer families, which make their characterization difficult. Thanks to its ability to separate small molecules based on their mass, size, shape, and charge, ion mobility-mass spectrometry (IM-MS) has emerged as a powerful tool for separating glycan isomers. Here, the potential of such a technique for the rapid characterization of main human milk oligosaccharides (HMOs) was investigated. Our study focused on 18 HMO standards. The IM-MS analysis enabled to distinguish almost all the HMOs studied, in particular thanks to the single ion mobility monitoring acquisition using the trapped ion mobility spectrometry device, providing high ion mobility resolution and enhanced ion mobility separation. Alternatively, the combination of IM-MS separation with MS/MS experiments has proven to increase performance in identifying HMOs and especially isomers poorly separated by ion mobility alone. Finally, collision cross-section values are provided for each species generated from the 18 HMOs standards, which can serve as an additional identifier to characterize HMOs.

CP-violation, asymmetries and interferences in toverline{t}phi

In this paper, we use the associated production of top-quark pairs ( toverline{t} ) with a generic scalar boson (ϕ) at the LHC (pp → toverline{t}phi ) to explore the sensitivity of a large set of observables to the sign of the CP mixing angle (α), present in the coupling between the scalar boson and the top quarks. The mass of the scalar boson is set to mϕ = 125 GeV (the Standard Model Higgs boson mass) and its coupling to top-quarks is varied such that α = 0°, 22.5°, 45.0°, 67.5°, 90.0°, 135.0° and 180.0°. Dileptonic final states of the toverline{t}phi system are used (pp → bℓ+νℓ overline{b} ℓ− overline{nu} ℓb overline{b} ), where the scalar boson is expected to decay according to ϕ → boverline{b} . A new method to reconstruct the scalar mass, originally designed for the low mass regime is used, improving the resolution of the Higgs mass by roughly a factor of two. A full phenomenological analysis is performed using Standard Model (SM) background and signal events generated with MadGraph5_aMC@NLO, in turn reconstructed using a kinematical fit. The most sensitive CP-observables are selected to compute Confidence Level (CL) limits as a function of the sign of the top quark Yukawa couplings to the ϕ boson. We also explore the sensitivity to interference terms using differential distributions and angular asymmetries. Given the significant difference between the pure scalar (σ0+) and pure pseudo-scalar (σ0−) production cross section values, it is unlikely the toverline{t}phi channel alone will be sensitive to the sign of the CP-mixing angle or interference terms, even at the end of the LHC. Using the {b}_2^{toverline{t}phi } and {b}_4^{toverline{t}phi } variables, exclusion limits at 95% CL for the CP-even and CP-odd components of the top quark Yukawa couplings are expected to be set to overset{sim }{kappa } ∈ [-0.698,+0.698] and |κ| ∈ [0.878,1.04], respectively, at the end of the High Luminosity phase of the LHC (HL-LHC) by using the dileptonic decay channel alone.

Prediction of Structures of Compounds Encountered in Complex Organic Matter with Highly Flexible Alkyl Chains Using Ion Mobility-Mass Spectrometry.

The chemical structure of an organic molecule has a direct influence on its three-dimensional conformation. One way to obtain information on this conformation is to use ion mobility spectrometry. This technique allows the separation of different isomers according to their collision cross section (CCS) with an inert gas. Smaller or more compact molecules will have lower collision cross section values than larger molecules. The CCS is an intrinsic ion parameter for a specific gas and is thus predictable. Today, calculations of rigid molecules are commonly performed to obtain additional structural information on an ion. However, calculations are more complex with very flexible molecules. In particular, molecules presenting long alkyl chains can yield a high number of conformers. Each conformer is then associated with a CCS value that is specific to it. We report, here, a methodology to predict CCS of flexible molecules. The used approach is based on automatic conformers research followed by geometry optimization and CCS calculations. Determination of theoretical and experimental CCS values for a rigid polycyclic aromatic hydrocarbons (PAHs) standard was used to calibrate the Mobcal software. Then, 13 standard molecules ranging from 4 to 19 carbon alkyl chains, including three long alkyl chain isomers of C22H38, were analyzed on a TWIMS-ToF and calculated using our methodology. CCS deviations between experimental and theoretical values were found to be less than 1.5% over the whole studied CCS range. This method was finally applied for structural analysis of petroleum compounds refractory to the hydro-denitrogenation process.

Collision Cross Section Prediction with Molecular Fingerprint Using Machine Learning.

High-resolution mass spectrometry is a promising technique in non-target screening (NTS) to monitor contaminants of emerging concern in complex samples. Current chemical identification strategies in NTS experiments typically depend on spectral libraries, chemical databases, and in silico fragmentation tools. However, small molecule identification remains challenging due to the lack of orthogonal sources of information (e.g., unique fragments). Collision cross section (CCS) values measured by ion mobility spectrometry (IMS) offer an additional identification dimension to increase the confidence level. Thanks to the advances in analytical instrumentation, an increasing application of IMS hybrid with high-resolution mass spectrometry (HRMS) in NTS has been reported in the recent decades. Several CCS prediction tools have been developed. However, limited CCS prediction methods were based on a large scale of chemical classes and cross-platform CCS measurements. We successfully developed two prediction models using a random forest machine learning algorithm. One of the approaches was based on chemicals’ super classes; the other model was direct CCS prediction using molecular fingerprint. Over 13,324 CCS values from six different laboratories and PubChem using a variety of ion-mobility separation techniques were used for training and testing the models. The test accuracy for all the prediction models was over 0.85, and the median of relative residual was around 2.2%. The models can be applied to different IMS platforms to eliminate false positives in small molecule identification.

Core-shell N-doped carbon nanofibers@poly(3,4-ethylenedioxythiophene): Flexible composite fibers for enhanced electromagnetic wave absorption

The conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is uniformly coated on the surface of N-doped carbon nanofibers (NCNFs) to construct NCNFs@PEDOT flexible composite fibers with dual three-dimensional conductive networks. The prepared samples are mixed with paraffin at different mass ratios (2 %, 5 %, 10 %, 15 %), NCNFs@PEDOT-10 % exhibits a maximum reflection loss (RL) of −66.9 dB at 2.6 mm, while NCNFs@PEDOT-5 % shows a maximum effective absorption bandwidth (EAB) of 6.72 GHz at 2.7 mm. The excellent electromagnetic (EM) wave absorption performance is attributed to the conduction loss in the conductive network; the interfacial polarization between NCNFs and PEDOT; and the dipole orientation polarization caused by N atom doping and graphite structural defects. Furthermore, the radar cross section (RCS) values of multilayer composites with positive and negative conductivity gradients are simulated. This work provides a reference for the research of flexible EM wave absorbers and the structural design of multilayer EM wave absorbing materials.

A new empirical systematic for (n, 2p) reaction cross sections around 14 MeV

In the present work, we proposed a new empirical systematic with which we can predict the (n, 2p) cross sections as an extension of the empirical rule on the basis of the statistical theory of nuclear reactions. It is obtained by fitting the experimental cross sections as a function of mass number, reaction Q–value, threshold energy and projectile energy. A new analysis of experimental data is performed for (n, 2p) reactions around 14 MeV energy. Besides, the present formula was expressed by a simple systematic with two fitting parameters. The predictions of this formula were discussed and compared with cross section measurements and empirical formulas found in the literature. Results show that the new empirical formula gives a good fit to predict the (n, 2p) cross sections around 14 MeV. This study can provide a reference to the (n, 2p) reaction channel considering the lack of measured cross section values.

Determination of Co57(n,xp ) cross sections using the surrogate reaction ratio method

The compound nuclei $^{58}\mathrm{Co}^{*}$ and $^{61}\mathrm{Ni}^{*}$ have been populated at overlapping excitation energies by transfer reactions $^{56}\mathrm{Fe}(^{6}\mathrm{Li},\ensuremath{\alpha})^{58}\mathrm{Co}^{*}$ (surrogate of $n+^{57}\mathrm{Co}$) at ${E}_{\mathrm{lab}}$ = 35.9 MeV and $^{59}\mathrm{Co}(^{6}\mathrm{Li},\ensuremath{\alpha})^{61}\mathrm{Ni}^{*}$ (surrogate of $n+^{60}\mathrm{Ni}$) at ${E}_{\mathrm{lab}}$ = 40.5 MeV, respectively. The $^{57}\mathrm{Co}(n,xp$) cross sections in the equivalent neutron energy range of 8.6--18.8 MeV have been determined within the framework of surrogate reaction ratio method using $^{60}\mathrm{Ni}(n,xp$) cross section values from the literature as reference. The proton decay probabilities of the compound systems have been determined by measuring evaporated protons at backward angles in coincidence with projectile-like fragments detected around the grazing angle. The measured $^{57}\mathrm{Co}(n,xp$) cross sections are in good agreement with both the predictions of talys-1.8 statistical model code with default parameters using different microscopic level densities and data evaluation library jeff-3.3 up to equivalent neutron energy $\ensuremath{\approx}12.6$ MeV, while for higher energies the measured $^{57}\mathrm{Co}(n,xp$) cross sections are found to be consistently higher than the predictions. However, the talys-1.8 calculations with modified values of input potential parameters provide a reasonable reproduction of the measured $^{57}\mathrm{Co}(n,xp$) cross sections for the entire neutron energy range. The observed discrepancies at higher energies between the experimental data and the predictions of both the jeff-3.3 library and the talys-1.8 calculations with default parameters indicate the need of new evaluations for this reaction.