Chemical Yields Research Articles

STUDIES TO ESTABLISH THE SCALING FACTOR METHODOLOGY FOR LIQUID RADIOACTIVE WASTE GENERATED BY TRIGA REACTOR

During TRIGA reactor operation significant amounts of liquid radioactive waste are generated requiring appropriate management to ensure their safe disposal. Radiological characterization is an important activity needed to accomplish the waste acceptance criteria for different management steps including disposal. The purpose of this paper is to assess the activity concentrations of the (_1^3)H , (_38^90)Sr, (_28^63)Ni (difficult-to-measure), and gamma emitters (easy-to-measure) radionuclides in liquid radioactive waste generated by the TRIGA reactor operation and to establish a correlation among them to determine the scaling factors for this waste category. The radiological protocols applied for (_28^63)Ni and (_38^90)Sr, separation and purification involve extraction chromatography using selective resins, while for (_1^3)H separation the distillation technique was applied. The assessment of gamma emitters was carried out using gamma-ray spectrometry and the detection of (_1^3)H , (_38^90)Sr, and (_28^63)Ni was performed by liquid scintillation counting. The chemical yield of each experiment was determined by measuring the carrier added in each test by inductively coupled plasma optical emission spectrometry. The activity concentrations of (_38^90)Sr, and (_28^63)Ni obtained were correlated with the activity concentration of (_27^60)Co for establishing the scaling factor for the liquid radioactive waste stream. There were obtained good correlations but more experimental data are needed to determine the relevant scaling factors for these difficult-to-measure radionuclides. The scaling factors, once established, will improve and optimize the radiological characterization methodology applied for liquid radioactive waste as an easy and rapid method for assessment of concentration activities of difficult-to-measure radionuclides. Until now, no scaling factors data were reported for this liquid radioactive waste generated by TRIGA reactor operated by Institute for Nuclear Research Pitesti. The results obtained in this work represent preliminary data for establishing correlations between difficult-to-measure and easy-to-measure radionuclides and will be used for developing a scaling factor methodology. This will further be used to determine the inventory of difficult-to-measure radionuclides in different waste streams generated by TRIGA operation and decommissioning (foreseen after 2035).

Production of oxygenated volatile organic compounds from the ozonolysis of coastal seawater

Abstract. Dry deposition of ozone (O3) to the ocean surface and the ozonolysis of organics in the sea surface microlayer (SSML) are potential sources of volatile organic compounds (VOCs) to the marine atmosphere. We use a gas chromatography system coupled to a Vocus proton-transfer-reaction time-of-flight mass spectrometer to determine the chemical composition and product yield of select VOCs formed from ozonolysis of coastal seawater collected from Scripps Pier in La Jolla, California. Laboratory-derived results are interpreted in the context of direct VOC vertical flux measurements made at Scripps Pier. The dominant products of laboratory ozonolysis experiments and the largest non-sulfur emission fluxes measured in the field correspond to Vocus CxHy+ and CxHyOz+ ions. Gas chromatography (GC) analysis suggests that C5–C11 oxygenated VOCs, primarily aldehydes, are the largest contributors to these ion signals. In the laboratory, using a flow reactor experiment, we determine a VOC yield of 0.43–0.62. In the field at Scripps Pier, we determine a maximum VOC yield of 0.04–0.06. Scaling the field and lab VOC yields for an average O3 deposition flux and an average VOC structure results in an emission source of 10.7 to 167 Tg C yr−1, competitive with the DMS source of approximately 20.3 Tg C yr−1. This study reveals that O3 reactivity to dissolved organic carbon can be a significant carbon source to the marine atmosphere and warrants further investigation into the speciated VOC composition from different seawater samples and the reactivities and secondary organic aerosol (SOA) yields of these molecules in marine-relevant, low NOx conditions.

Uncertainty-Aware Yield Prediction with Multimodal Molecular Features

Predicting chemical reaction yields is pivotal for efficient chemical synthesis, an area that focuses on the creation of novel compounds for diverse uses. Yield prediction demands accurate representations of reactions for forecasting practical transformation rates. Yet, the uncertainty issues broadcasting in real-world situations prohibit current models to excel in this task owing to the high sensitivity of yield activities and the uncertainty in yield measurements. Existing models often utilize single-modal feature representations, such as molecular fingerprints, SMILES sequences, or molecular graphs, which is not sufficient to capture the complex interactions and dynamic behavior of molecules in reactions. In this paper, we present an advanced Uncertainty-Aware Multimodal model (UAM) to tackle these challenges. Our approach seamlessly integrates data sources from multiple modalities by encompassing sequence representations, molecular graphs, and expert-defined chemical reaction features for a comprehensive representation of reactions. Additionally, we address both the model and data-based uncertainty, refining the model's predictive capability. Extensive experiments on three datasets, including two high throughput experiment (HTE) datasets and one chemist-constructed Amide coupling reaction dataset, demonstrate that UAM outperforms the state-of-the-art methods. The code and used datasets are available at https://github.com/jychen229/Multimodal-reaction-yield-prediction.

Effects of radiation dose and dose rate on alginate and the use of radiation degraded alginate for peanut

Aqueous solutions of alginate (4 %) with or without hydrogen peroxide (0–2 % H2O2) were irradiated under a gamma Co-60 source. The effect of dose rate on the radiation scission yield (Gs) of resulting irradiated alginate was determined. At the dose of 20 kGy, the G(s) value of irradiated alginate decreased with the increase dose rate, suggesting that the irradiation at a suitable dose rate could further improve the radiation chemical yield of degradation. For the alginate irradiated at the same dose rate, G(s) value increased with the increase of H2O2 concentration. Average molecular weight (Mw) and polydispersity index (PI) of irradiated alginate rapidly decreased with the increase in dose and further decreased by addition of H2O2. The oligoalginate with Mw ~ 9800 g/mol was obtained by radiation degradation of 4 % alginate solution containing 2 % H2O2 at dose of 20 kGy. Radiation scission of glycoside bonds and formation of carbonyl groups (C=O) were indicated in UV and FTIR spectra of irradiated alginate. Peanut seedlings were fertilized with alginate and oligoalginate solutions, and the results showed that all growth parameters of the treated plants were better than those of the control. Furthermore, the oligoalginate prepared by gamma irradiation can be applied as a plant growth promoter for agriculture production.

Synthesis and Photophysical Properties of β-Alkenyl-Substituted BODIPY Dyes by Indium(III)-Catalyzed Intermolecular Alkyne Hydroarylation.

A new atom-economical synthesis of β-alkenyl-substituted BODIPYs via indium(III)-catalyzed intermolecular alkyne hydroarylation with meso-substituted BODIPYs is described. While catalysis with InI3 allows the double β-functionalization of BODIPY, resulting in regioselectively branched β,β'-disubstituted alkenyl BODIPYs, catalytic InCl3 enables the formation of linear β-substituted alkenyl BODIPYs. Subsequent In(III)-catalyzed intermolecular alkyne hydroarylation allows the synthesis of unsymmetrical push-pull BODIPY derivatives. Therefore, indium catalysis offers complementary regioselectivity in good chemical yields and functional group tolerance. The resulting BODIPY dyes displayed bathochromically shifted absorption and emission according to the electron-nature of the substituents in the alkenyl moiety with high molar extinction coefficients (ε up to 88,200 M-1 cm-1) and quantum yields (0.14-0.96).

Electrochemical Multicomponent Cascade Radical Process Enabling Synthesis of Iodomethyl Spiropyrrolidinyl‐Oxindoles

Comprehensive SummaryA novel electrochemical multicomponent cascade reaction of indole‐tethered alkenes with CF3SO2Na and n‐Bu4NI has been developed, which enables the rapid assembly of spiropyrrolidinyl‐oxindoles in good yields. The experimental results and DFT calculations suggest that this reaction proceeds through the oxidation of CF3SO2Na, radical coupling with alkene, spirocyclization, oxidation of sulfinate, iodide substitution, and water coupling. This strategy features mild reaction conditions, easy‐to‐handle reactants, and good chemical yields. This finding not only enriches the research contents of indole‐tethered alkenes but also provides a green strategy for the construction of spiropyrrolidinyl‐oxindoles compared with the existing methodologies.

Influence of pollination in liquid suspension on the date palm (Phoenix dactylifera L.) Mejhoul cultivar in the Mexicali valley, Mexico

The pollination process is one of the most important contributors to a successful date production since the yield and quality of the fruit depends on its correct successful. Liquid pollination in the date palm production is a recently used technique that seeks to obtain acceptable fruit set percentages (FSP) with lower pollen consumption. In this study, during the 2021 and 2022 growing seasons, the effect of pollination with pollen grains in liquid suspension on the FSP in the date palm cultivar ‘Mejhoul’ was evaluated in the Mexicali Valley, Mexico. The applications were in various proportions of pollen in liquid suspension (1, 2, 3 and 4 g/L), with approximately 40 mL on each inflorescence. The results revealed that the best treatment was 4 g/L with an average FSP of 67.89 and 68.69% for the years 2021 and 2022 respectively, while the control treatment obtained 54.94 and 57.75%, for the same years. Likewise, this method did not affect the physical and chemical properties and yields. Finally, this study suggests that in addition to consuming a smaller amount of pollen, this method has better pollination efficiency.

Tobacco/Salvia miltiorrhiza Intercropping Improves Soil Quality and Increases Total Production Value

Unreasonable cultivation methods and management measures have led to widespread obstacles in tobacco continuous cropping in planting areas, resulting in reduced tobacco yield and soil degradation. Therefore, intercropping tobacco with other crops is an effective strategy to improve continuous cropping barriers. In this study, flue-cured tobacco NC102 and conventional planting varieties of Salvia miltiorrhiza were used as materials, and four treatments of flue-cured tobacco monoculture (CK), flue-cured tobacco, and Salvia miltiorrhiza at a ratio of 1:1 (TS11), 2:2 (TS22), and 2:3 (TS23), respectively, were set up to study their effects on soil microorganisms, physical and chemical properties, and yield and quality of flue-cured tobacco. The results showed that intercropping Salvia miltiorrhiza increased the number of soil bacteria and actinomycetes, decreased the number of fungi, and increased the activity of urease and sucrase. The content of available nitrogen and available phosphorus in intercropping Salvia miltiorrhiza soil was significantly higher than that of the flue-cured tobacco monoculture, while the content of available potassium was lower than that of the flue-cured tobacco monoculture. The soil environment was more conducive to the growth of flue-cured tobacco. Compared with the flue-cured tobacco monoculture, the proportion of superior tobacco in intercropping Salvia miltiorrhiza increased by 2.2–3.4%, and the ratio of potassium to chlorine in leaves of different parts of flue-cured tobacco increased by 12.3–75.0%. The content of total sugar and soluble sugar in middle and upper leaves of intercropping flue-cured tobacco was higher than that of the flue-cured tobacco monoculture, which improved the quality of flue-cured tobacco. From the analysis of the chemical composition of tobacco leaves, TS11 (flue-cured tobacco and Salvia miltiorrhiza intercropping row ratio of 1:1) had the best treatment effect, potassium content, total sugar, reducing sugar content, and potassium chloride ratio of flue-cured tobacco were the highest, the chlorine content was the lowest, and the quality was better than other treatments. From the analysis of total output value, the total output value of TS22 (flue-cured tobacco and Salvia miltiorrhiza intercropping row ratio of 2:2) was higher than that of other intercropping treatments. In 2018 and 2019, the total output value increased by 21.3% and 22.4%, respectively, compared with the flue-cured tobacco monoculture. The intercropping advantage was obvious, and the treatment effect was the best.

Impact of bio-digestate and fertilization on the soil chemical properties, growth and yield of maize (Zea mays L.)

Recognizing the significance of maize cultivation, it is imperative to determine the appropriate levels of NPK fertilizer along with the supplementary inclusion of bio-digestate (an organic fertilizer), to achieve optimal soil chemical properties and crop yields. Hence, a field study was conducted in 2022 at the Teaching and Research Farm of Bowen University, Iwo, Osun State, Nigeria. The study evaluated the effects of bio-digestate fertilizer (D), applied alone and integrated with urea (N), single superphosphate (P) and muriate of potash fertilizers (K) at low (N1K1P1) and high (N2P2K2) rates on soil chemical properties, growth, and yield of maize (Zea mays (L.). The treatments consisted of application of: D at 2500 L/ha alone, D + N1 P1 K1, D + N1 P1 K2, D + N1 P2 K1, D + N1 P2 K2, D + N2 P1 K1, D + N2 P1 K2, D + N2 P2 K1, D + N2 P2 K2, Control. N1 = 60 kg N/ha, N2 = 120 kg N/ha, P1 = 30 kg P2O5/ha, P2 = 60 kg P2O5/ha, K1 = 30 kg K/ha, K2 = 60 kg K/ha. The 10 treatments were arranged in a randomized complete block design and replicated three times. Results showed that bio-digestate (D) fertilizer applied alone or integrated with NPK fertilizers improved soil chemical properties, growth, and yield of maize compared with the control. High rate of fertilizer DN2P2K2 increased soil chemical properties and growth parameters of maize relative to low rates DN1P1K1 whereas a higher yield was recorded at a low rate DN1P1K1 relative to a high rate of fertilizer DN2P2K2. Overall, the treatment DN1P1K1 demonstrated the highest grain yield. D alone increased shelled maize yield by 187.9 % relative to no application of any amendment (control), also integrating D with N1P1K1 (DN1P1K1) increased maize yield by 97.2% relative to D alone. Bio-digestate can be used for maize cultivation in lonely soil especially when integrated with NPK fertilizer. Therefore, to avoid waste of fertilizer due to cost and negative environmental effects of excessive fertilization, the lower rate of NPK fertilizer: N (60 kg N/ha), P (30 kg P2O5/ha), and K (30 kg K/ha) with 2500 L/ha of bio-digestate (DN1P1K1) is recommended for sustainable maize production.

Influence of biochar and NPK on soil chemical properties, growth and yield of cabbage (Brassica oleracea L.)

Few studies have examined how fertilizers affect soil chemical properties, cabbage (Brassica oleracea L.) yield, and nutrient uptake in Ghana. This study examined how corn cob biochar (CCB) and NPK (15:15:15) fertilizer affected cabbage growth, yield, soil chemical properties, and nutrient uptake. The study was conducted during the 2021 major season at Soil Research Institute, Kwadaso. A 3×3 factorial experiment set out in a Randomized Complete Block Design with three replications was conducted. The treatments applied were control (No fertilizer), 50% NPK, 100% NPK, 2,500 kg ha-1 CCB, 50% NPK + 2,500 kg ha-1 CCB, 100% NPK + 2,500 kg ha-1 CCB, 5,000 kg ha-1 CCB, 50% NPK + 5,000 kg ha-1 CCB and 100% NPK + 5,000 kg ha-1 CCB. Application of 100% NPK resulted in the largest (2.99 cm) stem diameter. Application of 100% NPK + 5,000 kg ha-1 CCB resulted in the tallest plants (42.3 cm) and cabbage leaf spread (71.23 cm). Application of 100% NPK + 5,000 kg ha-1 CCB resulted in the largest cabbage head circumference (67.43 cm). The 100% NPK + 2,500 kg ha-1 CCB gave the highest yield (40679 kg ha-1). 100% NPK + 2,500 kg ha-1 CCB increased nitrogen uptake, 50% NPK + 5,000 kg ha-1 increased phosphorus and calcium uptake, 100% NPK + 5,000 kg increased potassium uptake, and 50% NPK + 2,500 kg increased magnesium uptake. Therefore, it is suggested that CCB and NPK fertilizers be applied to enhance the soil’s physical and chemical properties, nutrient uptake, and other factors contributing to cabbage growth and yield.

Desymmetric homologating annulation to access chiral pentafulvenes and their application in bioimaging

The architectural design of polycyclic/multisubstituted pentafulvenes has demonstrated great potential for the development of electrochromic materials and biologically active motifs. Unfortunately, the enantioselective construction of such distinctive cores with all carbon quaternary chiral centers has remained untouched to date. Herein, we disclose an enantioselective homologating annulation of cyclopent-4-ene-dione with 3-cyano-4-methylcoumarins through L-tert-leucine derived thiourea catalysis, affording a wide range of enantioenriched polycyclic multisubstituted embedded aminopentafulvenes with excellent stereocontrol (up to 99:1 er) and chemical yields up to 87%. A detailed photophysical and cytotoxicity analysis of racemic and chiral homologated adducts unveils the exceptional behavior of chiral adducts over their racemic analogs, highlighting the importance of stereoselectivity of the developed scaffolds. A cellular uptake experiment in a mammalian fibroblast cell line confirmed the potential of developed polycyclic aminopentafulvene cores as a highly promising labeling dye that can be utilized for bioimaging without any adverse effects.

Improving chemical reaction yield prediction using pre-trained graph neural networks

Graph neural networks (GNNs) have proven to be effective in the prediction of chemical reaction yields. However, their performance tends to deteriorate when they are trained using an insufficient training dataset in terms of quantity or diversity. A promising solution to alleviate this issue is to pre-train a GNN on a large-scale molecular database. In this study, we investigate the effectiveness of GNN pre-training in chemical reaction yield prediction. We present a novel GNN pre-training method for performance improvement.Given a molecular database consisting of a large number of molecules, we calculate molecular descriptors for each molecule and reduce the dimensionality of these descriptors by applying principal component analysis. We define a pre-text task by assigning a vector of principal component scores as the pseudo-label to each molecule in the database. A GNN is then pre-trained to perform the pre-text task of predicting the pseudo-label for the input molecule. For chemical reaction yield prediction, a prediction model is initialized using the pre-trained GNN and then fine-tuned with the training dataset containing chemical reactions and their yields. We demonstrate the effectiveness of the proposed method through experimental evaluation on benchmark datasets.

Galactic archaeology with [Mg/Mn] versus [Al/Fe] abundance ratios

Context. The diagram depicting the abundance ratios [Mg/Mn] versus [Al/Fe] has gained significant attention in recent literature as a valuable tool for exploring fundamental aspects of the evolution of the Milky Way (MW) and the nearby dwarf galaxies. In particular, this combination of elements is supposed to be highly sensitive to the history of star formation, unveiled by the imprints left on those abundances. Unfortunately, a complete discussion on the uncertainties associated with these nuclei is still missing, making it difficult to know how reliable the associated results are. Aims. In this work, we aim to analyse, by means of detailed chemical evolution models, the uncertainties related to the nucleosynthesis of Mg, Al, Mn, and Fe to show how different yield prescriptions can substantially affect the trends in the [Mg/Mn] versus [Al/Fe] plane. In fact, if different nucleosynthesis assumptions produce conflicting results, then the [Mg/Mn] versus [Al/Fe] diagram does not represent a strong diagnostic for the star formation history (SFH) of a galaxy. Methods. We discuss the results on the [Mg/Mn] versus [Al/Fe] diagram, as predicted by several MW and Large Magellanic Cloud (LMC) chemical evolution models adopting different nucleosynthesis prescriptions. Results. The results show that the literature nucleosynthesis prescriptions require some corrective factors to reproduce the APOGEE DR17 abundances of Mg, Al, and Mn in the MW and that the same factors can also improve the results for the LMC. In particular, we show that by modifying the massive star yields of Mg and Al, the behaviour of the [Mg/Mn] versus [Al/Fe] plot changes substantially. Conclusions. In conclusion, by changing the chemical yields within their error bars, one obtains trends that differ significantly, making it very difficult to draw any reliable conclusion on the SFH of galaxies. The proposed diagram is therefore very uncertain from a theoretical point of view, and it could represent a good diagnostic for star formation, only if the uncertainties on the nucleosynthesis of the above-mentioned elements (Mg, Mn, Al, and Fe) could be reduced by future stellar calculations.

Stereospecific Assembly of Trisubstituted Alkenes via Photoinduced Nitrogen‐Centered Radical‐Triggered C—C Bond Cleavage/Functionalization of Oxime Esters

Comprehensive SummaryA general and convenient photoredox‐catalyzed acylation and alkylcyanation of MBH acetates has been established, enabling the assembly of the C(sp2)–C(sp3) bond by a nitrogen‐centered radical strategy for the synthesis of trisubstituted alkenes in moderate to excellent chemical yields (48 examples in total). The reaction of MBH acetates with acyl (indanone) oxime esters afforded trisubstituted alkenes containing 1,4‐dicarbonyl groups. Interestingly, the use of Eosin Y as a photocatalyst in the catalytic system resulted in the formation of distal cyano group‐anchored trisubstituted alkenes via deconstructive functionalization of cycloketone oxime esters. Notably, these resulting 1,4‐dicarbonyl compounds could be applied to late‐stage transformations, providing important methods for the synthesis of dihydropyridazin‐3(2H)‐one.

Synthesis of Polysubstituted Naphthalenes by a Hydride Shift Mediated C-H Bond Functionalization/Aromatization Sequence.

A synthetic strategy for forming multisubstituted naphthalenes based on hydride shift mediated C(sp3)-H bond functionalization was developed. This strategy consists of three successive transformations: (1) an intramolecular hydride shift mediated C(sp3)-H bond functionalization; (2) a decarboxylative fragmentation; and (3) an oxidation reaction. When benzylidene malonates having a 2-alkoxyethyl group at the ortho position were treated with a catalytic amount of Al(OTf)3, the hydride shift/cyclization reaction proceeded smoothly to afford tetralin derivatives in good chemical yields. The resulting tetralins were easily converted into naphthalenes by exposing them to modified Krapcho decarboxylation reaction conditions (LiCl, DMSO, and heating under an O2 atmosphere). The one-pot operation of these two reactions was also realized.

Optimization and automation of the radiosynthesis of [18F]Lu-LuFL as a clinically useful PET ligand targeting FAP for tumor imaging

Recently, a novel radiohybrid tracer [18F]Lu-LuFL targeting the fibroblast activation protein (FAP) has been developed for PET imaging of solid tumors. This tracer has shown promising results, prompting us to conduct a first-in-human study to evaluate its efficacy for PET imaging of FAP in human body. In order to facilitate the routine production and clinical application of [18F]Lu-LuFL, a straightforward and efficient automated synthesis is described. The optimum labeling parameters were determined at laboratory scale, and subsequently incorporated into an automated production process. Further studies have demonstrated that clinical doses of [18F]Lu-LuFL can be prepared within 19 min, with excellent radio chemical purity (>99%) and activity yield (23.58% ± 2.20%, non-decay corrected), coupled with solid phase extraction (SPE) purification method. All the quality control results satisfy the required criteria for release. In conclusion, we have successfully synthesized [18F]Lu-LuFL with sufficient radioactivity and superior quality, thereby establishing its potential for further clinical application.

Dose Rate Effects on Hydrated Electrons, Hydrogen Peroxide, and a OH Radical Molecular Probe Under Clinical Energy Protons.

We report the dose rate dependence of radiation chemical yields (G value) of water radiolysis products under clinical energy protons (230 MeV) to understand mechanisms of the FLASH radiotherapy performed at ultra-high dose rate (>40 Gy/s). The G value of 7-hydoroxy-coumarin-3-carboxylic acid (7OH-C3CA) produced by reactions of coumarin-3-carboxylic acid (C3CA) with OH radicals and oxygen is evaluated by fluorescence method. Also, those of hydrated electrons and hydrogen peroxide are derived by absorption method using Saltzman and Ghomley techniques, respectively. Both G values of 7OH-C3CA and hydrated electrons decrease with increasing dose rate. The relative evolution of 7OH-C3CA is -39 ± 2% between 0.1 and 50 Gy/s. This value is higher than that of hydrated electrons, measured at -21 ± 4%. The G value of hydrogen peroxide in ultra-pure water also decreases with increasing dose rate. In comparison to these findings, we represent the increase of the G value of hydrogen peroxide with increasing dose rate in the mixture solution of MeOH and NaNO3, which act as scavengers of OH radicals and hydrated electrons, respectively, that decompose hydrogen peroxide. This finding indicates that a complex track structure can be expected with increasing dose rate and the reduction of OH radicals by forming hydrogen peroxide would be related to the sparing effect of healthy tissues.

Prediction of chemical reaction yields with large-scale multi-view pre-training

Developing machine learning models with high generalization capability for predicting chemical reaction yields is of significant interest and importance. The efficacy of such models depends heavily on the representation of chemical reactions, which has commonly been learned from SMILES or graphs of molecules using deep neural networks. However, the progression of chemical reactions is inherently determined by the molecular 3D geometric properties, which have been recently highlighted as crucial features in accurately predicting molecular properties and chemical reactions. Additionally, large-scale pre-training has been shown to be essential in enhancing the generalization capability of complex deep learning models. Based on these considerations, we propose the Reaction Multi-View Pre-training (ReaMVP) framework, which leverages self-supervised learning techniques and a two-stage pre-training strategy to predict chemical reaction yields. By incorporating multi-view learning with 3D geometric information, ReaMVP achieves state-of-the-art performance on two benchmark datasets. Notably, the experimental results indicate that ReaMVP has a significant advantage in predicting out-of-sample data, suggesting an enhanced generalization ability to predict new reactions. Scientific Contribution: This study presents the ReaMVP framework, which improves the generalization capability of machine learning models for predicting chemical reaction yields. By integrating sequential and geometric views and leveraging self-supervised learning techniques with a two-stage pre-training strategy, ReaMVP achieves state-of-the-art performance on benchmark datasets. The framework demonstrates superior predictive ability for out-of-sample data and enhances the prediction of new reactions.

Synthesis of gem-Difluorinated Keto-Sulfoxides from Sulfoxonium Ylides.

Organic molecules containing fluorine and sulfur atoms represent a large percentage of approved pharmaceuticals. Those with combination of both S and F atoms in their structure such as Xtandi, approved in 2012 for prostate cancer, indicates the importance of synthetic methods that accommodates both atoms in an organic moiety. In this study, a novel aspect of sulfoxonium ylide reactivity was explored, unveiling a streamlined and mild synthesis method for gem-difluorinated keto-sulfoxides. Our protocol offers a direct and practical approach to prepare these compounds in 14-80 % chemical yields, that were represented by 21 examples. NMR studies and Hammett correlations gave strong evidence about the mechanism of this transformation.

Volatile Compound Markers in Beef Irradiated with Accelerated Electrons.

This study focuses on the behavior of volatile organic compounds in beef after irradiation with 1 MeV accelerated electrons with doses ranging from 0.25 kGy to 5 kGy to find reliable dose-dependent markers that could be used for establishing an effective dose range for beef irradiation. GC/MS analysis revealed that immediately after irradiation, the chemical yield and accumulation rate of lipid oxidation-derived aldehydes was higher than that of protein oxidation-derived aldehydes. The nonlinear dose-dependent relationship of the concentration of volatile organic compounds was explained using a mathematical model based on the simultaneous occurrence of two competing processes: decomposition of volatile compounds due to direct and indirect action of accelerated electrons, and accumulation of volatile compounds due to decomposition of other compounds and biomacromolecules. A four-day monitoring of the beef samples stored at 4 °C showed that lipid oxidation-derived aldehydes, protein oxidation-derived aldehydes and alkanes as well as alcohol ethanol as an indicator of bacterial activity were dose-dependent markers of biochemical processes occurring in the irradiated beef samples during storage: oxidative processes during direct and indirect action of irradiation, oxidation due to the action of reactive oxygen species, which are always present in the product during storage, and microbial-enzymatic processes. According to the mathematical model of the change in the concentrations of lipid oxidation-derived aldehydes over time in the beef samples irradiated with different doses, it was found that doses ranging from 0.25 kGy to 1 kGy proved to be most effective for beef irradiation with accelerated electrons, since this dose range decreases the bacterial content without considerable irreversible changes in chemical composition of chilled beef during storage.