Kernel Development Research Articles

Extending GPU-accelerated Gaussian integrals in the TeraChem software package to f type orbitals: Implementation and applications.

The increasing availability of graphics processing units (GPUs) for scientific computing has prompted interest in accelerating quantum chemical calculations through their use. However, the complexity of integral kernels for high angular momentum basis functions often limits the utility of GPU implementations with large basis sets or for metal containing systems. In this work, we report the implementation of f function support in the GPU-accelerated TeraChem software package through the development of efficient kernels for the evaluation of Hamiltonian integrals. The high efficiency of the resulting code is demonstrated through density functional theory (DFT) calculations on increasingly large organic molecules and transition metal complexes, as well as coupled cluster singles and doubles calculations on water clusters. Preliminary investigations into Ni(I) catalysis with DFT and the photochemistry of MnH(CH3) with complete active space self-consistent field are also carried out. Overall, our GPU-accelerated software appears to be well-suited for fast simulation of large transition metal containing systems, as well as organic molecules.

Genetic analysis of maize crude fat content by multi-locus genome-wide association study

Crude fat is an important nutritional component of maize kernels. However, the genetic mechanisms underlying crude fat content in maize kernels remain elusive. Previous studies used single-model genome-wide association studies (GWAS) with limited population sizes, which can result in false positives of loci and hinder the identification of functional genes. Therefore, this study used a population consisting of 495 maize inbred lines, combined with 1.25 million single nucleotide polymorphisms (SNPs), and implemented GWAS using six models to identify quantitative trait nucleotides (QTNs) controlling crude fat content and to mine key genes. The results revealed a wide variation in crude fat content (0.62–16.03%) and broad-sense heritability (96.23%). In total, 744 significant QTNs were detected, with 147 co-located across different models, environments, and methods. Based on the 147 co-located QTNs, candidate genes were searched at 50 kb up- and downstream intervals of each QTN. We finally screened eight candidate genes (GRMZM2G169089, GRMZM2G117935, GRMZM2G002075, GRMZM2G368838, GRMZM2G058496, GRMZM2G090669, GRMZM2G001241, and GRMZM2G333454) related to crude fat content that exhibited high expression levels during kernel development in maize inbred line B73. Notably, GRMZM2G169089, GRMZM2G117935, GRMZM2G002075, and GRMZM2G368838 are involved in the linoleic acid metabolic pathway, oil metabolism, kernel growth, and development in maize. Furthermore, co-expression network analysis revealed that the eight candidate genes exhibited strong correlations with 30 known genes. Proteins encoded by candidate genes interact with various other proteins and play an important role in oil content and oleic acid metabolism in maize kernels. The best haplotypes of candidate genes might increase crude fat content without decreasing maize yield. These results broaden the understanding of the genetic mechanism of crude fat content and facilitate marker-assisted selection for high-crude fat breeding programs for maize.

Estimating the minimum ignition energy of spark-ignited fuel/air mixtures: preliminary steps towards a novel modelling approach

Abstract In spark-ignition (SI) engines, the achievement of a fast combustion with low cycle-to-cycle variation is highly dependent on the successful initiation of a flame kernel from the spark plug. Its growth can be sped up by increasing the electrical energy supply, but at the cost of higher plug wear, whereas too little energy may result in an ignition failure. Therefore, knowledge of the minimum ignition energy (MIE) of a fuel/air mixture is of key importance to guarantee a proper combustion process at minimal cost. To model the MIE several approaches have been proposed in literature, primarily derived from the experiments conducted by Lewis and Von Elbe and their resulting theory of quenching distances. However, these approaches appear in conflict with more recent experimental outcomes, and the impact of the ignition device is neglected. This work proposes a novel approach for modelling the MIE, which is based on a flame kernel expansion model recently proposed in another paper. In this approach, the proposed model, which has general validity, is specialized to the particular case of the estimation of the MIE, supplied via an electrical breakdown. A model advancement is also included that consists in the quantification, albeit at a preliminary level, of the impact of different gap distances and spark plug quenching effects on the flame kernel development. The results are validated against literature models and experimental data for two fuels, propane and hydrogen, and multiple equivalence ratios. In contrast with the noticeable MIE overestimation of literature models, for propane the proposed approach leads to better results compared to the experiments. Instead, for hydrogen a tendency towards a MIE underestimation is observed, especially for lean mixtures. The model is also tested for SI-engine-relevant conditions, showing satisfactory overall trends. The key source of error seems related to the very complex kernel-electrode interaction, the modelling of which will be improved in future developments.

Optical study on the auto-ignition and knocking behaviors of ammonia/PODE RCCI mode

Employing high-reactivity fuels such as polyoxymethylene dimethyl ethers (PODE) are effective ways to improve ammonia-based engine performance. However, abnormal combustion (i.e., knocking combustion) may be encountered at reactivity-controlled compression ignition (RCCI) mode. In this study, the auto-ignition and knocking behaviors of ammonia/PODE RCCI mode were studied in a highly-strengthened optical engine at different injection timing conditions, with synchronization measurement of in-cylinder pressure and high-speed photography. The port-injection of ammonia and direct injection of PODE were employed at an energy ratio of 80/20. Results shows that knock intensity is significantly increased with the advancement of injection timings under elevated thermodynamic conditions, accompanied by steep pressure peaks and pressure oscillations. Combustion visualization elucidates the relationship between auto-ignition (AI) progress and knock intensity. Pressure oscillations under knocking combustion are closely correlated to the interplay between different AI flame fronts. Further analysis identifies two distinct combustion characteristics, manifested in the most AI locations and the initial AI flame speed. Numerical results indicate that different AI behaviors are primarily determined by the degree of inhibition in PODE pre-flame reactions by ammonia dehydrogenation, which affects AI kernel development. The slow initial auto-ignition flame results in the formation of a sufficiently active premixed mixture in the unburned region before the initial AI flame front arrives. Once the second AI flame occurs, the active premixed mixture undergoes rapid combustion, leading to strong pressure waves.

Exploring Functional Gene XsPDAT1’s Involvement in Xanthoceras sorbifolium Oil Synthesis and Its Acclimation to Cold Stress

Phospholipid: diacylglycerol acyltransferase (PDAT) is crucial in triacylglycerol (TAG) synthesis as it represents the final rate-limiting step of the acyl-CoA-independent acylation reaction. PDAT not only regulates lipid synthesis in plants, but also plays an important function in improving stress tolerance. In this study, the full-length coding sequence (CDS) of XsPDAT1, totaling 2022 base pairs and encoding 673 amino acids, was cloned from Xanthoceras sorbifolium. The relative expression of XsPDAT1 was significantly and positively correlated with oil accumulation during seed kernel development; there were some differences in the expression patterns under different abiotic stresses. Transgenic Arabidopsis thaliana plants overexpressing XsPDAT1 were obtained using the Agrobacterium-mediated method. Under low-temperature stress, the transgenic plants exhibited a smaller decrease in chlorophyll content, a smaller increase in relative conductivity, and a larger increase in POD enzyme activity and proline content in the leaves compared with the wild type. Additionally, lipid composition analysis revealed a significant increase in unsaturated fatty acids, such as oleic (C18:1) and linoleic (C18:2), in the seeds of transgenic plants compared to the wild type. These results suggest that XsPDAT1 plays a dual role in regulating the ratio of fatty acid composition and low-temperature stress in plants.

Transcriptome analysis of the genes and regulators involving in vitamin E biosynthesis in Elaeagnus mollis diels.

Elaeagnus mollis is an important newly developing woody oil plant species and the vitamin E (VitE) content in its kernel oil is relatively high. In the present study, the VitE component content and functional genes involving in VitE biosynthesis in E. mollis kernel at different developmental stage were investigated. The VitE content increased with kernel development, reaching up to ~ 7.96mg/g oil in kernel mature stage. The content of tocopherol was much higher than that of tocotrienol and γ-tocopherol became the dominant component. E. mollis kernel extracts had relatively strong antioxidant capacity. We identified 17 genes (16 VTEs and 1 homogentisic acid geranylgeranyl transferase (HGGT)) directly involving in VitE biosynthesis in RNA-Seq data. Phylogenetic and qRT-PCR results indicated that the annotation and reliability of the RNA-Seq were accurate. Transient overexpression of EmVTE3 and EmWRKY13 in tobacoo leaves increased and decreased the VitE content to 192.18 and 118.29µg/g, respectively. Weighted gene co-expression analysis elucidated that the blue module showed significant correlation with tocopherol content. Co-expression network analysis revealed that 2-methyl-6-phytobenzoquinone methyltransferase (MPBQ-MT/VTE3) played a vital role and EmWRKY13 may be a key negative regulator in E. mollis VitE biosynthesis. This study not only revealed the traditional VitE biosynthesis pathway in E. mollis, but also set a solid foundation for future genetic breeding of this species.

Unrevealing the Halyomorpha halys Damage Fingerprint on Hazelnut Metabolome by Multiomic Platforms and AI-Aided Strategies.

The brown marmorated stink bug (Halyomorpha halys) poses a significant threat to hazelnut crops by affecting kernel development and causing quality defects, reducing the market value. While previous studies have identified bitter-tasting compounds in affected kernels, the impact of stink bug feeding on the hazelnut metabolome, particularly concerning aroma precursors, remains underexplored. This study aims to map the nonvolatile metabolome and volatilome of hazelnut samples obtained by caging H. halys on different cultivars in two locations to identify markers for diagnosing stink bug damage. Using a multiomic approach involving headspace solid-phase microextraction (HS-SPME), comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOF MS), and liquid chromatography-high-resolution mass spectrometry (LC-HRMS), both raw and roasted hazelnuts are analyzed, with artificial intelligence (AI) and machine learning tools employed to explore data correlations. The study finds that the hazelnut metabolome and volatilome exhibit high chemical complexity with significant classes of compounds such as aldehydes, ketones, alcohols, and terpenes identified in both raw and roasted hazelnuts. Multivariate analysis indicates that the orchard location significantly impacts the metabolome, followed by damage type, with cultivar differences being less pronounced. Partial least-squares discriminant analysis (PLS-DA) models achieve high predictive accuracy for orchard location (99%) and damage type (≈80%), with the roasted volatilome showing the highest predictive accuracy. Correlation matrices reveal significant relationships between raw hazelnut metabolites and aroma compounds in roasted samples, suggesting potential markers for stink bug damage that could guide the quality assessment and mitigation strategies. Data fusion techniques further enhance classification performance, particularly in predicting damage type, underscoring the potential of integrating multiple data sets for comprehensive quality assessment.

Co-localization of quantitative trait loci for pod and kernel traits and development of molecular marker for kernel weight on chromosome Arahy05 in peanut (Arachis hypogaea L.)

Key messageStable QTL for pod and kernel traits were co-localized on chromosome Arahy05, and an INDEL marker at 106,411,957 on Arahy05 was developed and validated to be useful for marker-assisted selection of kernel weight.Pod and kernel traits, such as hundred pod weight (HPW), and hundred kernel weight (HKW), along with pod and kernel sizes, are pivotal determinants of yield in peanut breeding programs. This study sought to identify quantitative trait loci (QTL) that are associated with these pod and kernel traits in peanuts. To achieve this, a recombinant inbred line (RIL) population, was derived from a cross between Yuhua15, a cultivar known for its high yield, and a germplasm accession W1202. The investigation uncovered stable and major QTL that are significantly associated with both pod and kernel weight and were consistently co-localized on chromosomes Arahy05 and Arahy08. Furthermore, an INDEL marker was identified and characterized in the QTL interval on Arahy05. An extensive re-sequencing analysis comprising 395 germplasm accessions led to the discovery of two principal haplotypes within a 500-kb window flanking the aforementioned INDEL marker. The haplotypes exhibited a significant correlation with the HKW in our diverse panel of germplasm accessions. Notably, the 170 accessions harboring the haplotype associated with an increased HKW primarily represented botanical varieties, specifically Arachis hypogaea var. hypogaea and A. hypogaea var. hirsuta. On the other hand, the 137 accessions associated with the alternative haplotype, which corresponded to a reduced HKW, were predominately identified as belonging to botanical varieties within A. hypogaea subsp. fastigiata. The INDEL marker located on Arahy05, which demonstrates close linkage to the pod and kernel traits, would be an efficient approach for marker-assisted selection (MAS) of pod and kernel weight in breeding programs.

The role of maize sap beetles (Coleoptera: Nitidulidae) and maize weevils (Coleoptera: Curculionidae) in the spread of Aspergillus flavus in pre-harvest maize in Kenya

Abstract The spread of toxigenic Aspergillus into maize by insects and the subsequent aflatoxin contamination poses a risk to humans and animals and has been investigated in North and South America. To evaluate this effect in an African context, Greenhouse studies were conducted in 2022 to determine the role of sap beetles, Carpophilus dimidiatus Fabricius, 1792 (Coleoptera: Nitidulidae) and maize weevils, Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae) on infection of maize kernels by Aspergillus flavus Link and the resultant aflatoxin accumulation. To test the beetles’ efficacy, treatments were applied on partially opened primary ears at 3 different stages of kernel development (BBCH 75, 83, and 87). The treatments were: (i) distilled water, (ii) water with A. flavus spores, (iii) maize grits, (iv) maize grits with A. flavus spores, (v) C. dimidiatus, (vi) C. dimidiatus with A. flavus spores, (vii) S. zeamais, and (viii) S. zeamais with A. flavus spores. Data on kernel infection, maize rotting, yield, and aflatoxin content in kernels were collected. The highest kernel spoilage and yield loss were recorded for the co-inoculation of S. zeamais and A. flavus spores, followed by S. zeamais without A. flavus spores, and then C. dimidiatus with the fungal spores. Inoculation of maize at the BBCH 83 growth stage resulted in the highest kernel damage and aflatoxin contamination. S. zeamais and, to a lesser extent, C. dimidiatus effectively spread the A. flavus inoculum into non-wounded ears, resulting in fungal and aflatoxin contamination. The yield loss from S. zeamais-Aspergillus co-inoculation occurred due to the grain rotting and actual feeding of the maize weevils. Thus, insect management is important in reducing pre-harvest contamination of maize with mycotoxigenic fungi and their resultant toxins.

Transcriptome analysis of lipid biosynthesis during kernel development in two walnut (Juglans regia L.) varieties of ‘Xilin 3’ and ‘Xiangling’

BackgroundWalnut is an oilseed tree species and an ecologically important woody tree species that is rich in oil and nutrients. In light of differences in the lipid content, fatty acid composition and key genes expression patterns in different walnut varieties, the key gene regulatory networks for lipid biosynthesis in different varieties of walnuts were intensively investigated.ResultsThe kernels of two walnut varieties, ‘Xilin 3’ (X3) and ‘Xiangling’ (XL) were sampled at 60, 90, and 120 days post-anthesis (DPA) to construct 18 cDNA libraries, and the candidate genes related to oil synthesis were identified via sequencing and expression analysis. A total of 106 differentially expressed genes associated with fatty acid biosynthesis, fatty acid elongation, unsaturated fatty acid biosynthesis, triglyceride assembly, and oil body storage were selected from the transcriptomes. Weighted gene co-expression network analysis (WGCNA), correlation analysis and quantitative validation confirmed the key role of the FAD3 (109002248) gene in lipid synthesis in different varieties.ConclusionsThese results provide valuable resources for future investigations and new insights into genes related to oil accumulation and lipid metabolism in walnut seed kernels. The findings will also aid future molecular studies and ongoing efforts to genetically improve walnut.

Genome-wide identification of the E-class gene family in wheat: evolution, expression, and interaction.

Wheat (Triticum aestivum L.) is among themost important crop worldwide. Given a growing population and changing climate, enhancing wheat yield is of great importance. Yield is closely associated with flower and spike development, and E-class genes play important roles in the flower and kernel development of plants. Currently, the absence of systematic analysis on the E gene family hinders our comprehension of their roles in plant growth and development. Identify E-class genes based on homologous sequence searches. Analyze the identified E-class genes through a series of gene family analyses. Determine the expression levels of wheat E-class genes by searching public databases. Validate the functions of these genes by transforming them into Arabidopsis. Finally, determine the interactions between the genes through yeast two-hybrid experiments. Fifteen E-class genes (TaEs) were identified in common wheat. Nine E-class genes were detected in five ancestral/closely related species, including one in Aegilops tauschii (AtE), one in T. Urartu (TuEs), two in T. turgidum (TtEs), two in T. dicoccoides (TdEs), and three in T. spelta (TsEs). The 24 E-class genes were classified into three subgroups using a phylogenetic approach. All genes were highly expressed in spikes, and most were only highly expressed at the floret meristem stage. The effects of TaSEP5-A on flowering and growth cycles were confirmed in homologous mutants and transgenic Arabidopsis thaliana. The E-class genes were able to regulate the growth cycle of Arabidopsis. Finally, we confirmed the interactions between TaSEP5-A and other wheat E-class genes based on yeast two-hybrid assays. Our findings provide information regarding the E-class genes in wheat and will potentially promote the application of these genes in wheat improvement.

N6-methyladenosine transcriptome-wide profiles of maize kernel development.

Maize (Zea mays L.) kernel development is a complex and dynamic process involving cell division and differentiation, into a variety of cell types. Epigenetic modifications, including DNA methylation, play a pivotal role in regulating this process. N6-methyladenosine modification is a universal and dynamic post-transcriptional epigenetic modification that is involved in the regulation of plant development. However, the role of N6-methyladenosine in maize kernel development remains unknown. In this study, we have constructed transcriptome-wide profiles for maize kernels at various stages of early development. Utilizing a combination of MeRIP-seq and RNA-seq analysis, we identified a total of 11,170, 10,973, 11,094, 11,990, 12,203 and 10,893 N6-methyladenosine peaks in maize kernels at 0, 2, 4, 6, 8, and 12 days after pollination, respectively. These N6-methyladenosine modifications were primarily deposited at the 3'-UTRs and were associated with the conserved motif-UGUACA. Additionally, we found that conserved N6-methyladenosine modification are involved in the regulation of genes that are ubiquitously expressed during kernel development. Further analysis revealed that N6-methyladenosine peak intensity was negatively correlated with the mRNA abundance of these ubiquitously expressed genes. Meanwhile, we employed phylogenetic analysis to predict potential regulatory proteins involved in maize kernels development and identified several that participate in the regulation of N6-methyladenosine modifications. Collectively, our results suggest the existence of a novel post-transcriptional epigenetic modification mechanism involved in the regulation of maize kernels development, thereby providing a novel perspective for maize molecular breeding.

PPR21 is involved in the splicing of nad2 introns via interacting with PPR–small MutS-related 1 and small PPR protein 2 and is essential to maize seed development

Pentatricopeptide repeat (PPR) proteins are a large group of eukaryote-specific RNA-binding proteins that play pivotal roles in plant organelle gene expression. Here, we report the function of PPR21 in mitochondrial intron splicing and its role in maize kernel development. PPR21 is a typical P-type PPR protein targeted to mitochondria. The ppr21 mutants are arrested in embryogenesis and endosperm development, leading to embryo lethality. Null mutations of PPR21 reduce the splicing efficiency of nad2 intron 1, 2, and 4 and impair the assembly and activity of mitochondrial complex I. Previous studies show that the P-type PPR protein EMP12 is required for the splicing of identical introns. However, our protein interaction analyses reveal that PPR21 does not interact with EMP12. Instead, both PPR21 and EMP12 interact with the small MutS-related (SMR) domain–containing PPR protein 1 (PPR-SMR1) and the short P-type PPR protein 2 (SPR2). PPR-SMR1 interacts with SPR2, and both proteins are required for the splicing of many introns in mitochondria, including nad2 intron 1, 2, and 4. These results suggest that a PPR21–(PPR-SMR1/SPR2)–EMP12 complex is involved in the splicing of nad2 introns in maize mitochondria.

Effect of high temperature on maize yield and grain components: A meta-analysis

Global warming poses a significant challenge to global food security, with maize playing a vital role as a staple crop in ensuring food availability worldwide. Therefore, investigating the impact of high temperature (HT) on maize cultivation is imperative for addressing food security concerns. Despite numerous studies exploring the effects of HT on maize growth and yield, a comprehensive understanding of these effects remains elusive due to variations in experimental environments, varieties, and growth stages. To solve these limitations, a meta-analysis was conducted to assess the effects of HT on maize yield and grain components, synthesizing data from 575 observations across 34 studies. The findings indicate that 1) HT significantly reduced grain yield by 32.7–40.9 % and grain starch content by 2.8–10.5 %; 2) the vicinity of kernel development stage (include silking, blister, milk) is the period when maize kernels are most sensitive to HT; 3) a significant negative correlation was observed between HT degree and their impact on grain yield (R2 = 0.38, P = 0.043); and 4) the effects of HT days and degrees on maize yield were equally important. In conclusion, this meta-analysis establishes a theoretical framework for enhancing the resilience of maize production and cultivation practices by comprehensively evaluating the impact of HT on yield and grain components.

Bending of bidirectional functionally graded nonlocal stress-driven beam

This paper provides a comprehensive analysis, using nonlocal stress-driven integral theory, of the static behavior of a nanoscale beam of bidirectionally graded materials. After a brief explanation of the mathematical formulation of BDFGMs, the work done and strain energy expressions derived from the displacement field are discussed. Variational formulations and Hamilton's principle are used to develop the equilibrium equation. An analytical development of the nonlocal kernel for stress-driven integral theory and formulated governing equation which was nondimensionalized later. Explicit equations for displacement and moment are obtained by solving this equation using the Laplace transformation. Three different boundary conditions are examined, and differences in the maximum displacement with respect to the nonlocal parameter and the two material FGM parameters are displayed both visually and in table form. The results exhibit excellent agreement and provide a standard for further research when they are closely compared to the existing numerical data. This work contributes to the knowledge of BDFGMs under nonlocal effects generated by stress-driven integral theory and offers solutions that have been confirmed for further investigation.

On the modes of nanosecond pulsed plasmas for combustion ignition of quiescent CH4-air mixtures

The effect of transient plasma modes on ignition kernel development are discussed here for a quiescent CH4-air combustion model system. A 10 ns high-voltage pulse was applied to a pin-to-pin electrode in lean fuel-air mixtures at room temperature and atmospheric pressure. High-impedance streamer, transient spark and low-impedance spark discharges were identified based on pulse waveforms of voltage and current. A sustained ignition kernel expansion was observed when the plasma discharge transitioned into a transient spark or spark discharge. The minimum ignition energy was obtained at the transient spark mode, which has less than a third of the energy or Coulomb transfer compared to the low-impedance spark. Employing repetitive 10-pulse sequence at 10 kHz, the lean-fuel limit was extended from an equivalence ratio of 0.6 for the single pulse ignition to 0.5. The use of repetitive pulses also allowed streamer breakdown or spark initiation to occur at a lower voltage.

Combining No-Tillage with Hairy Vetch Return Improves Production and Nitrogen Utilization in Silage Maize.

The combination of no-till farming and green manure is key to nourishing the soil and increasing crop yields. However, it remains unclear how to enhance the efficiency of green manure under no-till conditions. We conducted a two-factor field trial of silage maize rotated with hairy vetch to test the effects of tillage methods and returning. Factor 1 is the type of tillage, which is divided into conventional ploughing and no-tillage; factor 2 is the different ways of returning hairy vetch as green manure, which were also compared: no return (NM), stubble return (H), mulching (HM), turnover (HR, for CT only), and live coverage (LM, for NT only). Our findings indicate that different methods of returning hairy vetch to the field will improve maize yield and quality. The best results were obtained in CT and NT in HM and LM, respectively. Specifically, HM resulted in the highest dry matter quality and yield, with improvements of 35.4% and 31.9% over NM under CT, respectively. It also demonstrated the best economic and net energy performance. However, other treatments had no significant effect on the beneficial utilization and return of nutrients. The LM improved yields under NT by boosting soil enzyme activity, promoting nitrogen transformation and accumulation, and increasing nitrogen use efficiency for better kernel development. Overall, NTLM is best at utilizing and distributing soil nutrients and increasing silage maize yield. This finding supports the eco-efficient cultivation approach in silage maize production in the region.

Effects of Osmotic Dehydration on Mass Transfer of Tender Coconut Kernel.

Tender coconut water has been very popular as a natural beverage rich in various electrolytes, amino acids, and vitamins, and hence a large amount of tender coconut kernel is left without efficient utilization. To explore the possibility of making infused tender coconut kernel, we investigated the effects of two osmosis methods, including solid-state osmotic dehydration and liquid-state osmotic dehydration, as well as two osmosis agents such as sorbitol and sucrose, on the mass transfer of coconut kernel under solid-state osmotic dehydration conditions. The results showed that under the conditions of solid-state osmosis using sucrose and liquid-state osmosis using sucrose solution, the water diffusion coefficients were 9.0396 h-1/2 and 2.9940 h-1/2, respectively, with corresponding water mass transfer coefficients of 0.3373 and 0.2452, and the equilibrium water loss rates of 49.04% and 17.31%, respectively, indicating that the mass transfer efficiency of solid-state osmotic dehydration of tender coconut kernel was significantly higher than that of liquid-state osmotic dehydration. Under solid osmosis conditions, the water loss rates using sucrose and sorbitol were 38.64% and 41.95%, respectively, with dry basis yield increments of 61.38% and 71.09%, respectively, demonstrating superior dehydration efficiency of sorbitol over sucrose under solid-state osmosis. This study can provide a reference for the theoretical study of the mass transfer of tender coconut kernel through osmotic dehydration, and also provide technical support for the development and utilization of tender coconut kernel.

Physically-informed change-point kernels for variable levels of physical knowledge inclusion in Gaussian processes

The relative balance between physics and data within any physics-informed machine learner is an important modelling consideration to ensure that the benefits of both physics and data-based approaches are maximised. An over reliance on physical knowledge can be detrimental, particularly when the physics-based component of a model may not accurately represent the true modelled system. An under utilisation of physical knowledge potentially wastes a valuable resource, along with benefits in model interpretability and reduced demand for expensive data collection. Although adjusting the relative levels of physics and data reliance within a model is possible through the adaptation of the model structure, in practice, this can be challenging, with the relative balance produced by new model structures not always clear before they are implemented. This paper presents a means of being able to tune the balance of physics and data reliance within a model through the development of physically-informed change-point kernels for Gaussian processes. These combine more structured physical kernels, capable of enforcing physically derived behaviours, with flexible, general purpose kernels, and provide means to dynamically change the relative levels of reliance on physics and data within a model.

Computational insights into flame development and emission formation in an ammonia engine with hydrogen-assisted pre-chamber turbulent jet ignition

Ammonia, as a promising green fuel for achieving carbon neutrality and zero-carbon emissions, encounters obstacles in practical engine applications due to its intrinsic combustion properties like low burning velocity and high autoignition temperature. Hydrogen-assisted pre-chamber turbulent jet ignition (TJI) technology has recently demonstrated great potential in extending the lean limits and enhancing the stability of ammonia combustion. As such, this study conducts a comprehensive analysis on the flame development and emission formation processes under the active pre-chamber TJI mode fueled with ammonia and hydrogen using computational fluid dynamics (CFD) modeling integrated with detailed chemical kinetics, particularly focusing on the effects of hydrogen energy ratio and spark timing. It is found that the active ammonia-hydrogen TJI engine is typically characterized by four primary physical processes involving H2 mixture preparation in the pre-chamber, flame kernel formation and development within the pre-chamber, the formation and ejection of hot jet across the orifices, and the turbulent flame initiation and propagation in the main chamber. Hydrogen injection holds a scavenging effect on the residuals in the pre-chamber while forms fuel stratification near the spark plug, enhancing the ignition stability. Besides, the current combustion mode is commonly characterized by two-stage heat release in the main chamber, but exhibits a three-stage heat release as increasing the premixed H2 ratio. The first stage is dominated by a hot jet flame, the second stage is characterized by turbulent flame propagation or autoignition, and the third stage is induced by a secondary jet ejected from the pre-chamber, which becomes more prominent as the H2 ratio increases. Hydrogen blending could not only facilitate the turbulent flame propagation of NH3-air mixture in the main chamber but also enhance the initiation of flame kernel in the pre-chamber, thereby promoting the overall combustion process and potentially improving the thermal efficiency. The N2O emission is produced in two distinct stages, wherein N2O is generated and undergoes conversion during the main combustion phase, while unburned crevice gases mix with burned gases and convert into N2O during the expansion stroke. Increasing the premixed hydrogen ratio leads to an increased in-cylinder temperature, which in turn facilitates a reduction in N2O emissions and mitigates unburned ammonia. Furthermore, optimization of the spark timing is required after implementing the hydrogen addition into the intake manifold to achieve desirable combustion phasing and further improve the thermal efficiency. Finally, a novel combustion concept, denoted as TJI assisted compression ignition mode, is proposed for achieving high thermal efficiency in ammonia engines via adopting high compression ratio and premixed ammonia-hydrogen charge under the TJI strategy.