Mixture Components Research Articles

Molecular Understanding of Activity Changes of Alcohol Dehydrogenase in Deep Eutectic Solvents.

Deep eutectic solvents (DESs) have emerged as promising solvents for biocatalysis. While their impact on enzyme solvation and stabilization has been studied for several enzyme classes, their role in substrate binding is yet to be investigated. Herein, molecular dynamics (MD) simulations of horse-liver alcohol dehydrogenase (HLADH) are performed in choline chloride-ethylene glycol (ChCl-EG) and choline chloride-glycerol (ChCl-Gly) at varying water concentrations. In the DES solutions, the active site was significantly constricted, and its flexibility reduced when compared to the aqueous medium. Importantly, the cavity size follows a similar trend as the catalytic activity of HLADH and as such explains previously observed activity changes. To understand the impact on the binding of the substrate (cyclohexanone), an umbrella sampling (US) setup was established to calculate the free energy changes along the substrate binding tunnel of HLADH. The US combined with replica exchange and NADH in its cofactor pocket provided the best sampling of the entire active site, explaining why the cyclohexanone binding on HLADH is reduced with increasing DES content. As different components in these multicomponent mixtures influence the substrate binding, we additionally applied the US setup to study the ability of the DES components to be present inside the substrate tunnel. The presented approach may become useful to understand enzyme behaviors in DESs and to enable the design of more enzyme-compatible and tunable solvents.

Guest Segregation in Heteromeric Multicage Systems.

Dynamically interconvertible metallo-supramolecular multicomponent assemblies, coexisting orthogonally in solution, serve as simplified mimics for complex networks found in biological systems. Building on recent advances in controlling the nonstatistical self-assembly of heteroleptic coordination cages and heteromeric completive self-sorting, i.e., the coformation of multiple low-symmetry assemblies, we herein describe the first instance of emerging functionality from a heteromeric multicage system. In particular, one heteroleptic cage coexists in equilibrium with one or two different homoleptic cages, each capable of preferentially encapsulating one out of three guests within their cavities. Guest segregation occurs under thermodynamic control and can be reached following several distinct paths. Each pathway involves different sequential transformations, eventually leading to the same outcome. We found that the most complex mixture of components (three ligands, three guests, plus palladium cations) always yields an ordered, pathway-independent final state of three coexisting host-guest species, thus representing a case of simplexity in self-sorted systems. This study forms a basis for expanding the scope of dynamic transformation processes implemented in multicage host-guest systems. Together with the incorporation of stimuli-responsive elements and other functionality, complex cage populations with bioinspired applications in controllable compound separation schemes, compartmentalized cascade reactions, and multistep (even bifurcated) molecular information processing will become accessible.

AECuration: Automated event curation for spike sorting.

Spike sorting is a commonly used analysis method for identifying single-units and multi-units from extracellular recordings. The extracellular recordings contain a mixture of signal components, such as neural and non-neural events, possibly due to motion and breathing artifacts or electrical interference. Identifying single and multi-unit spikes using a simple threshold-crossing method may lead to uncertainty in differentiating the actual neural spikes from non-neural spikes. The traditional method for classifying neural and non-neural units from spike sorting results is manual curation by a trained person. This subjective method suffers from human error and variability and is further complicated by the absence of ground truth in experimental extracellular recordings. Moreover, the manual curation process is time consuming and is becoming intractable due to the growing size and complexity of extracellular datasets. To address these challenges, we, for the first time, present a novel automatic curation method based on an autoencoder model, which is trained on features of simulated extracellular spike waveforms. The model is then applied to experimental electrophysiology datasets, where the reconstruction error is used as the metric for classifying neural and non-neural spikes. As an alternative to the traditional frequency domain and statistical techniques, our proposed method offers a time-domain evaluation model to automate the analysis of extracellular recordings based on learned time-domain features. The model exhibits excellent performance and throughput when applied to real-world extracellular datasets without any retraining, highlighting its generalizability. This method can be integrated into spike sorting pipelines as a pre-processing filtering step or a post-processing curation method.

Numerical solution of a nonlinear model of chromatography considering different isotherms and gradient profiles

In gradient chromatography, the mobile phase composition is progressively altered to regulate the propagation rates of the injected mixture components. Resultantly, improved separation of mixture components can be attained, the recycling time that must pass between two consecutive injections can be reduced, and, hence, the column’s efficiency and selectivity can be enhanced. A coupled modeling framework, integrating a lumped kinetic model and the convection–diffusion equation for solvent volume fraction, is employed to approximate the process. The influence of different isotherm models on the process dynamics is examined through numerical simulations. A semi-discrete second-order finite volume scheme is suggested to approximate the model equations. Impacts of positive and negative gradients, gradient shapes, gradient starting and ending times, axial dispersion, Henry’s constants, nonlinearity coefficients, mass transfer coefficients, and different adsorption isotherms are investigated. The theoretical findings presented in this study may facilitate further advancements in the field of gradient elution chromatography.

The effect of synthetic wax additives on adhesive properties of bitumen binders

Introduction. Currently, in road construction, in order to reduce energy costs and harmful emissions, warm asphalt concrete mixture technologies are being increasingly used. One way to reduce the temperature of asphalt concrete mixture prepared is to use additives based on natural and synthetic waxes. In this regard, it is important to study the influence of wax additives on the properties of bitumen binder as a basic component of asphalt concrete mixture. The adhesion between the binder and the mineral filler is the most important property that determines the durability of an asphalt concrete pavement. The purpose of this article is to study the effect of synthetic wax additives on the adhesive properties of bitumen.Materials and methods. The characteristics of the studied synthetic wax additives Viskodor PV-2, Sasobit and Licomont BS-100 have been presented. To simulate binder aging, the heating method in a thin layer, according to GOST 18180, was used with the temperature control time increased to 9 hours. To assess the adhesion between original and modified bitumen binder, as well as the aged binder, the method of boiling stone material coated with bitumen was used, and the assessment of its appearance in accordance with GOST 11508 was made. The study of the adhesion mechanism for the bitumen binder and the mineral filler was carried out by means of spectral analysis.Results and discussion. The influence of synthetic wax additives on the adhesion between bitumen binder and mineral material was analyzed. A change in the adhesive properties of bitumen modified with the studied additives during thermal-oxidative aging was revealed. A comparison was made of the IR spectra of the original and modified bitumen before and after interaction with stone material and the differences in the mechanisms of affecting the adhesion to the mineral filler by the introduced additives were determined. It has been established that the Viskodor PV-2 additive significantly improves bitumen adhesion. Moreover, the effect of improved bitumen adhesion with this additive remains after thermal-oxidative aging, though slightly reduced. Imported additives Sasobit and Licomont BS-100 have a significantly less impact on the adhesive properties of bitumen.Сonclusion. The results obtained show that the use of synthetic wax additives improves the adhesive properties of bitumen, which can positively affect the durability of the road surface. Since the domestic additive Viskodor PV-2 is superior in the effect of improving the adhesive properties of bitumen compared to the studied additives Sasobit and Licomont BS-100, the introduction of this additive into production instead of expensive imported additives will provide both improvement in the quality of asphalt concrete pavement and reduction of costs.

A method to predict binary eutectic mixtures for mechanochemical syntheses and cocrystallizations

Mechanochemical syntheses may benefit from the formation of a liquid eutectic intermediate. The software PoEM predicts the eutectic point in a binary mixture from the thermodynamic data and the interaction modes of the two components of the mixture.

Toxic effects and mechanisms of nanoplastics and sulfonamide antibiotics on Scenedesmus obliquus.

The prevalence of nanoplastics (NPs) and sulfonamide antibiotics (SAs) in the aquatic environment is potentially harmful to the environment, and these pollutants are often present in the environment in the form of composite ones, thereby introducing more complex effects and hazards to the environment. Therefore, it is crucial to investigate the toxic effects of the individual target pollutants and their mixtures. In this study, we used Scenedesmus obliquus as the test organisms, two types of NPs: polystyrene (PS) and amine-modified (NH2-PS), four SAs: sulfapyridine (SPY), sulfamethazine (SMR), sulfamethoxypyridazine (SMP), and sulfamethoxazole (SMZ), and their eight binary mixtures were examined. We investigated the toxic interactions of the eight binary mixtures on Scenedesmus obliquus and assessed the impact of the 14 mixtures on the physiological and biochemical properties of Scenedesmus obliquus. Interaction of pollutant assemblages with algal cells observed using field emission scanning electron microscopy. The results showed that the six target pollutants and their eight binary mixtures were significantly toxic to Scenedesmus obliquus within 96 h. The toxicity of individual pollutants was in the order of SPY (EC50: 12.38 mg/L) > SMZ (EC50: 20.43 mg/L) > SMP (EC50: 32.96 mg/L) > SMR (EC50: 41.06 mg/L) > PS (EC50: 284.13 mg/L) > NH2-PS (EC50: 754.13 mg/L); the toxicity of binary mixtures composed of NPs and SAs (89.13 ∼ 1905.46 mg/L) was generally less toxic than that of unitary SAs (12.38 ∼ 41.06 mg/L). Suggesting that the presence of NPs reduced the toxicity of the SAs. The different types of NPs influenced the interaction and toxicity of the mixtures. The effects-based model deviation ratio method was used to quantitatively assess the interactions of the mixture systems in the 10∼90 % experimental effect range. The majority of the PS-containing mixtures exhibited antagonistic interactions. The interactions of NH2-PS-containing mixtures on Scenedesmus obliquus showed different interactions depending on the concentration ratios of the mixture components. The exposure of two NPs and four SAs and their binary mixtures differently promoted or inhibited superoxide dismutase and catalase activities in algal cells to different degrees and resulted in elevated levels of malondialdehyde content, suggesting that oxidative stress led to significant inhibition of chlorophyll content, total protein content, and growth of algal cells. The SEM image can be a more intuitive means of observing the interaction of nanoplastics with algal cells. These findings offer valuable data for the ecological risk assessment of NPs and SAs.

Upaya Meningkatkan Hasil Belajar IPA Melalui Metode Pembelajaran Interaktif

The low learning outcomes of the science subject matter were caused by teachers. After the teacher felt a decrease in students’ interest in science learning. It can be observed that there is still material that seems difficult for children to understand: one of which is related to "everyday material according to its components (single substances and mixtures)". The purpose of this study is none other than to improve the learning outcomes of class V students of SDN 12 Banyuasin I with learning methods. This study is based on Classroom Action Research which consists of two parts. Qualitative data was obtained through observation instruments of single substances and mixtures of students. The interactive learning model is designed to allow students to ask their own questions and get answers. This interactive learning model can also be understood as learning that emphasizes communication between students and students and teachers in direct interaction with learning resources. After seeing the evaluation results, the teacher felt a decrease in students’ interest in science learning. It can be concluded that the average science learning score of class V students of SDN 12 Banyuasin I after using the interactive method where cycle I was 68.0 and cycle II was 89.3, so that the average from Cycle I to Cycle II can be known.

Exploring the Therapeutic Promise of Melittin: Anti-Inflammatory and Anti-Cancer Applications of Bee Venom

Bee venom, a complex mixture of bioactive components, has garnered attention for its therapeutic properties, with melittin identified as its primary active component. This review highlights the potential of melittin in treating inflammation and cancer, two major health challenges. Inflammatory diseases, characterized by dysregulated immune responses, benefit from melittin's anti-inflammatory effects, including the inhibition of pro-inflammatory cytokines and activation of anti-inflammatory signaling pathways. Both preclinical and clinical studies have demonstrated melittin's ability to reduce inflammation across various disease models. In oncology, melittin has shown promising anti-cancer effects by inhibiting cell proliferation and inducing apoptosis in cancer cells. Recent evidence suggests melittin's efficacy against breast cancer and its potential application in other malignancies, such as prostate, colorectal, and pancreatic cancers. Additionally, melittin enhances the effectiveness of conventional treatments like chemotherapy and radiation. Despite its therapeutic promise, the potential toxicity and adverse effects of melittin necessitate careful investigation. Current research focuses on strategies to mitigate toxicity and improve its safety profile. This review underscores the significant progress in understanding melittin's mechanisms of action and therapeutic potential, emphasizing the need for further studies to develop safe and effective melittin-based treatments for inflammatory and cancerous diseases.

Опытно-промышленная линия производства гранулированной асфальтобетонной смеси

The paper presents the results of calculation of a pilot production line for granulated asphalt concrete mixture with inclusion of phosphogypsum and secondary polyethylene terephthalate. The authors propose a method of mixing asphalt mixture components by pelletising. The authors selected the production units of the pilot line, gave recommendations on the minimum permissible technical and operational characteristics of the equipment. The authors have developed a brief technological regulation of production, energy and resource intensity of production was determined. In addition, it allowed them to calculate the need for human resources, means of mechanisation and determine the cost characteristics of the target material. The presented data are quite complete for drawing up the terms of reference for designing a pilot production line and determining its cost parameters. This makes it possible to comprehensively characterise the developed road material both from the point of view of the level of technical and operational indicators and from the economic point of view. The paper expands the understanding of the methods of production of asphalt concrete mixtures and the raw material base of road construction.

Effects of dichlorobenzene, toluene, benzene and formaldehyde chemicals on Drosophila melanogaster mortality.

Environmental exposures to volatile organic compound (VOC) mixtures have received increasing attention, yet the risks are under studied. This study aimed to explore the risks of combined exposures to several commonly detected VOCs and to draw attention to the necessity of studying long-term and low-concentration environmental exposure patterns. In this study, we examined the effects of long-term and low-concentration exposures to VOCs like 1,2-dichlorobenzene, benzene, toluene and formaldehyde either alone or in combination on D. melanogaster mortality. A quantitative relationship was established between 1,2-dichlorobenzene concentration and mortality. Additionally, 1,2-dichlorobenzene was more toxic than toluene, and males were more sensitive to 1,2-dichlorobenzene. In cocktail, 1,2-dichlorobenzene + benzene, 1,2-dichlorobenzene acted as an antagonist and interaction type may depend on component concentration. Antagonistic interaction was also found in twice mixture of toluene + benzene + formaldehyde and the degree of antagonism decreased with increasing concentrations of formaldehyde + benzene. The observed interactions and variations in their type or degree relative to mixture component concentrations may be attributed to inter-component metabolic interference and metabolic saturation.

Effects of Intercropped Insectary Plants (Sweet Alyssum, Coriander, and White Mustard) on Elemental Composition and Antioxidant Levels in Broad Bean Plants.

Insectary plants, such as sweet alyssum, coriander, and white mustard, are well known for their traits that attract beneficial insects, allowing them to protect crops from pests. The aim of the study was to analyze the compounds that are important in the antioxidant response, such as malondialdehyde, ascorbic acid, proline, total phenolics, and total flavonoids, as well as the content of elements, including macroelements (K, Mg, Na, Ca, P, and S) and heavy metals (Cd, Cu, Zn, Pb, Ni, Mn, and Fe) in broad bean plants. These plants were grown in field conditions as the main protected plant alongside a mixture of three insectary plants at different proportions of the individual components. The soil was analyzed in terms of the above-mentioned elements, as well as in terms of its enzymatic activity (arylsulfatase, β-glucosidase, dehydrogenase, FDA (fluorescein diacetate), and acid phosphatase). The introduction of insectary plant mixtures did not cause major changes in the content of the elements in the soil. The changes in the content of elements in broad bean leaves depended on the type of element and the proportion of individual components in the companion plant mixture. However, a general trend of increasing macronutrient content was observed, influenced by the presence of companion plants. All types of companion plant mixtures used enhanced the activity of FDA, while the mixture with 50% sweet alyssum additionally caused an increase in arylsulfatase activity (more than 2 fold). The companion plants improved the physiological condition of the protected plant, which was reflected in the reduced content of proline and total flavonoids. Considering the response of the protected plant to the proposed intercropped plant mixtures and their effect on broad bean growth, it appears that the most suitable mixtures are those with an equal share of all three plant species or a mixture with a predominance of sweet alyssum.

Selection of Components and Methods of Modification of Soil Cement to Improve the Performance Properties of Subgrade

Purpose. The main objective of the scientific article is a reasonable selection of soil-cement reinforcing structural elements and methods of modifying the soil-cement structure to strengthen the subgrade for railroad tracks. Methodology. For the construction of soil-cement reinforcing elements for a combined railway track using drilling and mixing technology, a number of tasks were solved, including: a reasonable selection of the components and modifiers of the soil-cement element; determination of the properties of the components; establishment of operational requirements for soil-cement and its composition; design of optimal compositions with specified performance characteristics, taking into account the properties of soils and operating modes. Findings. The influence of soil-cement components on the rheological properties of soil-cement mixtures and the physical and mechanical properties of soil-cement was studied. Based on the data processing by statistical analysis, the optimal content of the constituent components of soil-cement mixtures was selected to ensure the technological and operational performance of soil-cement for different types of soils and to strengthen the soil base during track construction. The influence of mineral granular, fibrous and chemical modifiers on the properties of soil cement was investigated. Originality. The possibility of using vertical reinforcing elements made of soil cement with the necessary technological and operational parameters obtained by drilling and mixing technology to strengthen the subgrade, taking into account the stress-strain state and morphology of the soil bases, has been determined. Based on the study, the author made an attempt to select the components and develop optimal soil cement compositions for strengthening the subgrade of a railroad for a combined track. The directions of modification of soil cement with mineral, fiber and chemical additives are also considered. Practical value. The study makes it possible to obtain soil-cement elements of optimal composition and properties for different types of soils and stress-strain states in order to vertically strengthen the soil bases for the railway track. To modify the structure of soil cement and minimize cement consumption, it is proposed to use fiber fibers as modifying reinforcement components. To increase the density, crack resistance, strength, and modulus of deformability and improve the plasticity of the mixture, it is recommended to use chemical modifiers up to 0.3 % and to save cement – particles of fine industrial waste in the form of ground slag or stone grinding screenings in the amount of 20...30 %.

Asphalt mixture image segmentation by RAN-UNet based on attention mechanism and multi-scale feature fusion

Asphalt mixtures exhibit dimensional complexity and morphological diversity, with blurred component boundaries hindering accurate mesostructure restoration. A convolutional neural network model RAN-UNet based on attention mechanisms and multi-scale feature fusion was proposed in this paper. The threshold segmentation method, U-Net and its improved models were compared to process CT images of asphalt mixtures, and the model performance and segmentation accuracy were evaluated for aggregates and voids within asphalt mixtures of various gradations. The applicability of methods to different gradation and components of the asphalt mixture were analyzed. The results showed that RAN-UNet has a better predictive ability and robustness than U-Net and its commonly used improved models. It can predict the morphology of target objects more accurately and restore the angularity of aggregates to a greater extent. This study provide an efficient and highly accurate method for the field of asphalt mixture image segmentation.

Transcending Resolution Limits in HPLC and Diffusion NMR.

Mixture analysis is crucial in many areas of chemistry, and a wide variety of separation methods are in use. A common method for physical separation is high-performance liquid chromatography (HPLC), but resolution is a problem: chemically similar species coelute. An alternative approach is diffusion-ordered NMR spectroscopy (DOSY), in which the signals of mixture components are separated according to the diffusion coefficient. Again, separation is limited if species diffuse similarly or have overlap in their NMR spectra. Using the two techniques in combination can resolve both NMR spectra and the elution profiles of individual components, even where both techniques fail when used in isolation. Recording diffusion NMR data as a function of HPLC retention time gives a three-dimensional (3D) data set that can be analyzed using multiway statistical methods. PARAFAC analysis of diffusion NMR data measured from HPLC eluate for commercial "monoacetin" (a mixture of glycerol and its mono-, di-, and triacetates) yielded fully resolved and quantitative NMR spectra and elution profiles for all four components, whereas neither HPLC nor diffusion NMR applied independently was able to resolve the components.

Hybrid Process Flow Diagram for Separation of Fusel Oil into Valuable Components

Ethanol production by fermentation results in obtaining, in addition to the main product, ethyl alcohol, by-products and secondary products, which include carbon dioxide, fusel oil, and ester–aldehyde cut. Fusel oil, despite its low yield and the large volume of ethanol production, accumulates at distilleries, which ultimately raises the question of its disposal or the rational use of this by-product. Fusel oil, being a complex mixture, can serve as a source of technical alcohols used in various sectors of the economy, including the food industry, pharmaceuticals, organic synthesis, perfume, and cosmetics industries, as well as the production of paints and varnishes. However, the complexity of using fusel oil lies in its difficult separation. The reason for this is the presence of water, which forms low-boiling azeotropes with aliphatic alcohols. Our study aimed to develop a process flow diagram (PFD) that allows individual components from fusel oil to be obtained without extraneous separating agents (not inherent in fusel oil). This condition is necessary to obtain products labeled as natural for further use in the food, perfume, cosmetic, and pharmaceutical industries. The distinctive feature of this work is that the target product is not only isoamyl alcohol but also all other alcohols present in the composition of fusel oil. To achieve this goal and create a mathematical model, the Aspen Plus V14 application, the Non-Random Two Liquid (NRTL) thermodynamic model, and the Vap-Liq/Liq-Liq phase equilibrium were used. Fusel oil separation was modeled using a continuous separation PFD to obtain ethanol, water, isoamyl alcohol, and raw propanol and butanol cuts. The Sorel and Barbet distillation technique was used to isolate ethanol. The isolation of isopropanol and 1-propanol, as well as isobutanol and 1-butanol, was modeled using the batch distillation method. The isolation of fusel oil components was based on their thermodynamic properties and the selection of appropriate techniques for their separation, such as extraction, distillation, pressure swing distillation, and decantation. The simulation of fusel oil separation PFD showed the possibility of obtaining the components of a complex mixture without separating agents, as discussed earlier. Ethanol corresponds to the quality of rectified ethyl alcohol, and 1-butanol and isoamyl alcohols to anhydrous alcohols, whereas isopropanol (which contains an admixture of ethanol), 1-propanol, and isobutanol are obtained as aqueous solutions of different concentrations of alcohols. However, due to a distillation boundary in the raw propanol and butanol cuts, these mixtures cannot be separated completely, which leads to the production of intermediate fractions. To eliminate intermediate fractions and obtain anhydrous isopropanol, 1-propanol, and isobutanol in the future, it is necessary to solve the dehydration problem of either fusel oil or the propanol–butanol mixture.

Investigation of Separating Temperature-Induced Structural Strain Using Improved Blind Source Separation (BSS) Technique.

The strain data acquired from structural health monitoring (SHM) systems of large-span bridges are often contaminated by a mixture of temperature-induced and vehicle-induced strain components, thereby complicating the assessment of bridge health. Existing approaches for isolating temperature-induced strains predominantly rely on statistical temperature-strain models, which can be significantly influenced by arbitrarily chosen parameters, thereby undermining the accuracy of the results. Additionally, signal processing techniques, including empirical mode decomposition (EMD) and others, frequently yield unstable outcomes when confronted with nonlinear strain signals. In response to these challenges, this study proposes a novel temperature-induced strain separation technique based on improved blind source separation (BSS), termed the Temperature-Separate Second-Order Blind Identification (TS-SOBI) method. Numerical verification using a finite element (FE) bridge model that considers both temperature loads and vehicle loads confirms the effectiveness of TS-SOBI in accurately separating temperature-induced strain components. Furthermore, real strain data from the SHM system of a long-span bridge are utilized to validate the application of TS-SOBI in practical engineering scenarios. By evaluating the remaining strain components after applying the TS-SOBI method, a clearer understanding of changes in the bridge's loading conditions is achieved. The investigation of TS-SOBI introduces a novel perspective for mitigating temperature effects in SHM applications for bridges.

A fluorescence approach for assessing the composition of evaporating droplets

Accurate measurement of chemical composition is vital for understanding heat and mass transfer mechanisms in two-phase flows like sprays. This Letter presents an optical method based on laser-induced fluorescence and fluorescence lifetime measurement. While solvatochromism—shifts in the emission and absorption spectra based on solvent type that alter fluorescence intensity—is well-documented for many fluorescent dyes, fluorescence lifetime offers distinct advantages for two-phase flow applications. Unlike intensity-based methods, lifetime measurements exhibit greater resilience to light attenuation and scattering at liquid/gas interfaces and allow for more flexible detection band selection. The technique leverages the fluorescence lifetime of eosin Y, which is sensitive to solvent polarity while remaining unaffected by temperature—a crucial feature for systems with fluctuating temperature and composition. We validate this method using acoustically levitated droplets, showing that eosin Y's fluorescence lifetime can reliably distinguish components in binary mixtures like ethanol/water and isopropanol/water. The high volatility of ethanol and isopropanol causes significant cooling during droplet vaporization, leading to water condensation from the surrounding air. This approach enables detailed analysis of complex evaporation and condensation dynamics.

Bayesian nonparametric mixture of experts for inverse problems

Large classes of problems can be formulated as inverse problems, where the goal is to find parameter values that best explain some observed measures. The relationship between parameters and observations is typically highly non-linear, with relatively high dimensional observations and correlated multidimensional parameters. To deal with these constraints via inverse regression strategies, we consider the Gaussian Local Linear Mapping (GLLiM) model, a special instance of mixture of expert models. We propose a general scheme to design a Bayesian nonparametric GLLiM model to avoid any commitment to an arbitrary number of experts. A tractable estimation algorithm is designed using variational Bayesian expectation-maximisation. We establish posterior consistency for the number of mixture components after the merge-truncate-merge algorithm post-processing. Illustrations on simulated data show good results in terms of recovering the true number of experts and the regression function.

Micronutrient Content of Aboveground Biomass as Influenced by Different Proportions of Medicago media Pers. in Two-Component Alfalfa–Grass Mixtures

The aim of this study was to determine the effect of different proportions of hybrid alfalfa (Medicago media Pers.) in two-component mixtures with festulolium (Festulolium braunii (K. Richt.) A. Camus) and orchard grass (Dactylis glomerata L.) on the micronutrient content of aboveground biomass. The study was conducted in 2011–2013 in Poland. The experiment had a split-plot design with four replications, and the experimental variables were as follows: (i) mixtures: Dactylis glomerata (Dg) + Medicago media (Mm) and Festulolium braunii (Fb) + Medicago media (Mm), and (ii) proportion of Medicago media seeds in the mixture: 30%, 50%, and 70%. Pure-sown Dactylis glomerata and pure-sown Festulolium braunii were the control treatments. The proportion of hybrid alfalfa in the biomass yield of mixtures increased throughout the study, and this species was the dominant component of the sward already in the second year, regardless of the proportion of sown seeds. Orchard grass exerted greater competitive pressure on alfalfa than festulolium. Pure-sown Dactylis glomerata accumulated more manganese (Mn) and iron (Fe) than pure-sown Festulolium braunii; no significant differences in the copper (Cu) and zinc (Zn) content of aboveground biomass were found between species. The aboveground biomass of mixtures was characterized by higher Cu content and lower Mn content than the biomass of grass monocultures. As a component of mixtures, alfalfa had a negative influence on the Fe content of aboveground biomass (dry matter basis). No significant differences in Cu and Mn content were observed between the mixtures. The Fb50% + Mm50% mixture had the highest Zn content, and the Fb70% + Mm30% mixture had the highest Fe content. The present findings suggest that practical two-component alfalfa–grass mixtures should be composed based on species competitiveness and selection of a grass component adapted to local agroecological conditions, rather than on the proportion of alfalfa seeds in the mixture.