Hasil untuk "math-ph"

Chaimaa Hakim, Hélène Carrère, Abdessadek Essadek et al.

This study proposes a circular economy strategy to recover phenolic compounds by valorizing shrimp shell waste into a chitosan biosorbent (CH-B). Its adsorption efficiency was evaluated compared to commercial activated carbon (AC) and synthetic XAD-4 resin. Kinetic analysis revealed that while both pseudo-first-order (PFO) and pseudo-second-order (PSO) models exhibited high correlations (R²<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mtext> </mtext><mo>≥</mo></mrow></semantics></math></inline-formula> 0.96), both CH-B and XAD-4 resin were best described by the PFO model. This aligns with diffusion-controlled processes consistent with the porous and physical nature of these adsorbents. In contrast, AC followed the PSO model. Isotherm modeling indicated that CH-B and AC fit the Temkin model, reflecting heterogeneous surfaces, whereas XAD-4 followed the Langmuir model (monolayer adsorption). Notably, CH-B exhibited a maximum adsorption capacity (q_m) of 229.2 mg/g, significantly outperforming XAD-4 (104.8 mg/g) and AC (90.2 mg/g). Thermodynamic and kinetic modeling confirmed that the adsorption mechanism was governed by a combination of electrostatic interactions, π–π stacking, and hydrogen bonding between the hydroxyl/amine groups of chitosan and phenolic compounds. Optimization using Box–Behnken design for CH-B showed optimal acidic pH and moderate temperature but non-significant effect of CH-B dose in the experimental domain. Optimisation results showed unexpected high removal efficiency at low CH-B dosages. A tentative explanation may be adsorbent aggre-gation, which needs to be confirmed by further experimental evidence.

Ignacio Sánchez-Gendriz, Ivanovitch Silva, Luiz Affonso Guedes

Kolmogorov–Arnold networks (KANs) represent a promising modeling framework for applications requiring interpretability. In this study, we investigate the use of KANs to analyze time series of water quality parameters obtained from a publicly available dataset related to an aquaponic environment. Two water quality indices (WQIs) were computed—a linear case based on the weighted average WQI, and a non-linear case using the weighted quadratic mean (WQM) WQI, both derived from three water parameters: pH, total dissolved solids (TDS), and temperature. For each case, KAN models were trained to predict the respective WQI, yielding explicit algebraic expressions with low prediction errors and clear input–output mathematical relationships. Model performance was evaluated using standard regression metrics, with <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>R</mi><mn>2</mn></msup></semantics></math></inline-formula> values exceeding 0.96 on the hold-out test set across all cases. Specifically for the non-linear WQM case, we trained 15 classical regressors using the LazyPredict Python library. The top three models were selected based on validation performance. They were then compared against the KAN model and its symbolic expressions using a 5-fold cross-validation protocol on a temporally shifted test set (approximately one month after the training period), without retraining. Results show that KAN slightly outperforms the best tested baseline regressor (multilayer perceptron, MLP), with average <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>R</mi><mn>2</mn></msup></semantics></math></inline-formula> scores of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.998</mn><mo>±</mo><mn>0.001</mn></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.996</mn><mo>±</mo><mn>0.001</mn></mrow></semantics></math></inline-formula>, respectively. These findings highlight the potential of KAN in terms of predictive performance, comparable to well-established algorithms. Moreover, the ability of KAN to extract data-driven, interpretable, and lightweight symbolic models makes it a valuable tool for applications where accuracy, transparency, and model simplification are critical.

Xiaoyu Xue, Haiqing Tian, Kai Zhao et al.

The pH value of maize silage can accurately reflect its quality. In this study, a colorimetric sensor array (CSA) combined with hyperspectral imaging (HSI) was used to predict the pH value of maize silage during secondary fermentation. Seventeen color-sensitive dyes were used to construct the CSA, which was subsequently applied to capture the volatile odor profiles of maize silage samples. Hyperspectral images of the color-sensitive dyes on the CSA were acquired using the HSI technique. Different algorithms were used to preprocess the raw spectral data of each dye, and a partial least squares regression (PLSR) model was built for each dye separately. Subsequently, the adaptive bacterial foraging optimization (ABFO) algorithm was employed to identify three color-sensitive dyes that demonstrated heightened sensitivity to pH variations in maize silage. This study further compared the capabilities of individual dyes, as well as their combinations, in predicting the pH value of maize silage. Additionally, a novel feature wavelength extraction method based on the ABFO algorithm was proposed, which was then compared with two traditional feature extraction algorithms. These methods were combined with PLSR and backpropagation neural network (BPNN) algorithms to construct a quantitative prediction model for the pH value of maize silage. The results show that the quantitative prediction model constructed based on three dyes was more accurate than that constructed based on an individual dye. Among them, the ABFO-BPNN model constructed on the basis of combined dyes had the best prediction performance, with prediction correlation coefficient (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>R</mi></mrow><mrow><mi>P</mi></mrow><mrow><mn>2</mn></mrow></msubsup></mrow></semantics></math></inline-formula>), root mean square error of the prediction set (<i>RMSEP</i>), and ratio of performance deviation (<i>RPD</i>) values of 0.9348, 0.3976, and 3.9695, respectively. The aim of this study was to develop a reliable evaluation model to achieve fast and accurate predictions of silage pH.

Andrea Pastore, Denis Badocco, Luca Cappellin et al.

Seven increasing levels of water salinity from 0.029 to 0.600 M (as NaCl) were used to investigate the dependence of pH measurement, performed using colorimetric sensor arrays (CSAs), on ionic strength. The CSAs were arrays of sensing spots prepared in the form of sol–gel-embedding Bromothymol Blue (BB) and Bromocresol Green (BCG) in a porous nitrocellulose support. The support was impregnated over the entire thickness (≈100 µm), allowing for the signal (Hue) acquisition on the opposite side to the contact with the sample solution. Three CSAs were prepared, M1, M2, and M3. M1 contained a free cationic surfactant, hexadecyltrimethylammonium p-toluenesulfonate (CTApTs), for modulating the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>p</mi><mi>K</mi></mrow><mrow><mi>a</mi></mrow></msub></mrow></semantics></math></inline-formula> of the indicators. In M2, the surfactant dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DTSACl) was covalently bonded to the sol–gel. M3 was prepared like M2 but using a larger amount of ethanol as the solvent for the synthesis. The modulation of the CTApTs or the DTSACl concentration enabled the tuning of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>p</mi><mi>K</mi></mrow><mrow><mi>a</mi></mrow></msub></mrow></semantics></math></inline-formula>. In general, the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>p</mi><mi>K</mi></mrow><mrow><mi>a</mi></mrow></msub></mrow></semantics></math></inline-formula> modulation ability decreased with the increase in salinity. The presence of a surfactant covalently linked to the backbone partially reduced the competitiveness of the anionic species, improving the results. Nevertheless, the salt effect was still present, and a correction algorithm was required. Between pH 5.00 and 12.00, this correction could be made automatically by using spots taken as references to produce sensors independent of salinity. As the salt effect is virtually absent above 0.160 M, M2 and M3 can be used for future applications in seawater.

Zahed Ghelichkhah, Digby D. Macdonald, Gregory S. Ferguson

An impedance model based on the Volmer–Heyrovsky–Tafel mechanism was developed to study the kinetics of the hydrogen evolution reaction on polycrystalline gold electrodes at moderate overpotentials in aqueous H₂SO₄ (0.5 and 1.0 M) solutions. The model was optimized on data from potentiodynamic polarization and electrochemical impedance spectroscopy, and model parameters were extracted. Consistent with expectations, the magnitude of the impedance data indicated a higher rate of hydrogen evolution at lower pH. Also, the fractional surface coverage of adsorbed hydrogen (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>θ</mi></mrow><mrow><mi>H</mi><mi>a</mi><mi>d</mi><mi>s</mi></mrow></msub></mrow></semantics></math></inline-formula>) increases with increasing overpotential but the small value of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>θ</mi></mrow><mrow><mi>H</mi><mi>a</mi><mi>d</mi><mi>s</mi></mrow></msub></mrow></semantics></math></inline-formula> indicates only weak adsorption of H on gold. Tafel slopes and exchange current densities were estimated to be in the range of 81–124 mV/dec, and 10⁻⁶ and 10⁻⁵ A/cm² in H₂SO₄ (0.5 and 1.0 M), respectively. The results show that the model accounts well for the experimental data, such as the steady-state current density. Sensitivity analysis reveals that the electrochemical parameters (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>α</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo> </mo><msub><mrow><mi>α</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo> </mo><msubsup><mrow><mi>k</mi></mrow><mrow><mn>1</mn></mrow><mrow><mn>0</mn></mrow></msubsup><mo>,</mo><mo> </mo><msubsup><mrow><mi>k</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow><mrow><mn>0</mn></mrow></msubsup><mo>,</mo><mo> </mo><msubsup><mrow><mi mathvariant="normal">a</mi><mi mathvariant="normal">n</mi><mi mathvariant="normal">d</mi><mo> </mo><mi>k</mi></mrow><mrow><mn>2</mn></mrow><mrow><mn>0</mn></mrow></msubsup><mo>)</mo></mrow></semantics></math></inline-formula> associated with the kinetics of the hydrogen evolution reaction have a major impact on the calculated impedance but the standard rate constant for hydrogen oxidation reaction (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>k</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow><mrow><mn>0</mn></mrow></msubsup><mo>)</mo></mrow></semantics></math></inline-formula> does not strongly affect the calculated impedance.

Qiuyue YE, Zhengchun HU, Ziyi WANG et al.

Sulfidated zero-valent iron (S–nZVI) has been extensively utilized in wastewater treatment in recent years due to its superior electron transfer efficiency and selectivity. Integrating S–nZVI with advanced oxidation technology enhances the catalytic performance of the material, leading to efficient pollutant degradation. This study employs thiourea as the sulfur source to prepare highly active S–nZVI and constructs an S–nZVI-activated per-disulfide PDS oxidation system to achieve efficient tetracycline degradation. The composition and surface morphology of S–nZVI is characterized using scanning electron microscopy (SEM), X–ray diffraction (XRD), specific surface area (BET), and X–ray photoelectron spectroscopy (XPS). The effects of the molar ratio (S/Fe), vulcanization time, S–nZVI dosage, PDS concentration, initial pH of the solution, and coexisting ions on tetracycline (TC) degradation are examined. Active species quenching experiments and electron paramagnetic resonance (EPR) experiments explore TC degradation by both free radical and non-radical active species, while liquid chromatography-mass spectrometry (LC–MS) analyzes the potential pathways of tetracycline degradation. Test results indicated that vulcanization modification increases the specific surface area of nano-zero-valent iron (nZVI), and iron (Fe) and sulfur (S) are uniformly distributed on the surface of the material. The impact of S/Fe on TC degradation is minimal, and the degradation rate correlates positively with the dosage of S–nZVI and PDS concentration but shows a decreasing trend with prolonged vulcanization time. The S–nZVI/PDS system exhibits an enhanced TC degradation effect across a wide pH range (pH=5～9). The presence of different anions in the reaction solution variably inhibits the degradation rate of TC, with <inline-formula><tex-math id="Z-20230915161918">$\mathrm{HCO}_3^- $</tex-math></inline-formula> having the most significant effect. At a S/Fe ratio of 0.028, a vulcanization time of 2 h, an S–nZVI dosage of 1 g/L, a PDS concentration of 2 mmol/L, and an unadjusted initial pH, the degradation rate of TC reaches 94.6% after 120 min of reaction. In addition to common free radicals (<inline-formula><tex-math id="Z-20230915161856">$\mathrm{SO}_4^{\cdot -} $</tex-math></inline-formula> and <inline-formula><tex-math id="Z-20240621124114">${\mathrm{HO}}^{\;\cdot } $</tex-math></inline-formula>), the active species in the S–nZVI/PDS system include the non-radical active substance Fe(Ⅳ), which has a minor effect on TC degradation. The primary pathways of TC degradation involve specific functional group cleavage and ring-opening reactions, ultimately leading to oxidative degradation into CO₂ and H₂O.

Kevin Hoffstadt, Marcell Nikolausz, Simone Krafft et al.

With the increasing use of renewable energy resources for the power grid, the need for long-term storage technologies, such as power-to-gas systems, is growing. Biomethanation provides the opportunity to store energy in the form of the natural gas-equivalent biomethane. This study investigates a novel plug flow reactor that employs a helical static mixer for the biological methanation of hydrogen and carbon dioxide. In tests, the reactor achieved an average methane production rate of 2.5 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mfrac><mrow><msub><mrow><mi>L</mi></mrow><mrow><msub><mrow><mi>C</mi><mi>H</mi></mrow><mn>4</mn></msub></mrow></msub></mrow><mrow><msub><mrow><mi>L</mi></mrow><mrow><mi>R</mi></mrow></msub><mo>∗</mo><mi mathvariant="normal">d</mi></mrow></mfrac></mrow></semantics></math></inline-formula> (methane production [L_CH4] per liter of reactor volume [L_R] per day [d]) with a maximum methane content of 94%. It demonstrated good flexibilization properties, as repeated 12 h downtimes did not negatively impact the process. The genera <i>Methanothermobacter</i> and <i>Methanobacterium</i> were predominant during the initial phase, along with volatile organic acid-producing, hydrogenotrophic, and proteolytic bacteria. The average ratio of volatile organic acid to total inorganic carbon increased to 0.52 ± 0.04, while the pH remained stable at an average of pH 8.1 ± 0.25 from day 32 to 98, spanning stable and flexible operation modes. This study contributes to the development of efficient flexible biological methanation systems for sustainable energy storage and management.

Hongxu Li, Qiaomei Wang, Houqiao Wang et al.

Catechins are pivotal determinants of tea quality, with soil environmental factors playing a crucial role in the synthesis and accumulation of these compounds. To investigate the impact of changes in tea garden soil environments on the catechin content in sun-dried tea, this study measured the catechin content in soil samples and corresponding tea leaves from Nanhua, Yunnan, China. By integrating the variations in catechin content with those of 17 soil factors and employing COX regression factor analysis, it was found that pH, organic matter (OM), fluoride, arsenic (As), and chromium (Cr) were significantly correlated with catechin content (<i>p</i> < 0.05). Further, using the LASSO regression for variable selection, a model named LCLN-CA was constructed with four variables including pH, OM, fluoride, and As. The LCLN-CA model demonstrated high fitting accuracy with AUC values of 0.674, 0.784, and 0.749 for catechin content intervals of CA ≤ 10%, 10% < CA ≤ 20%, and 20% < CA ≤ 30% in the training set, respectively. The validation set showed AUC values of 0.630, 0.756, and 0.723, respectively, indicating a well-calibrated curve. Based on the LCLN-CA model and the DynNom framework, a visual prediction system for catechin content in Yunnan sun-dried tea was developed. External validation with a test dataset achieved an <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>A</mi><mi>c</mi><mi>c</mi><mi>u</mi><mi>r</mi><mi>a</mi><mi>c</mi><mi>y</mi></mrow></semantics></math></inline-formula> of 0.870. This study explored the relationship between soil-related factors and variations in catechin content, paving a new way for the prediction of catechin content in tea and enhancing the practical application value of artificial intelligence technology in agricultural production.

Antonio Aslan, José-Luis Díez, Alejandro José Laguna Sanz et al.

Most advanced technologies for the treatment of type 1 diabetes, such as sensor-pump integrated systems or the artificial pancreas, require accurate glucose predictions on a given future time-horizon as a basis for decision-making support systems. Seasonal stochastic models are data-driven algebraic models that use recent history data and periodic trends to accurately estimate time series data, such as glucose concentration in diabetes. These models have been proven to be a good option to provide accurate blood glucose predictions under free-living conditions. These models can cope with patient variability under variable-length time-stamped daily events in supervision and control applications. However, the seasonal-models-based framework usually needs of several months of data per patient to be fed into the system to adequately train a personalized glucose predictor for each patient. In this work, an in silico analysis of the accuracy of prediction is presented, considering the effect of training a glucose predictor with data from a cohort of patients (population) instead of data from a single patient (individual). Feasibility of population data as an input to the model is asserted, and the effect of the dataset size in the determination of the minimum amount of data for a valid training of the models is studied. Results show that glucose predictors trained with population data can provide predictions of similar magnitude as those trained with individualized data. Overall median root mean squared error (RMSE) (including 25% and 75% percentiles) for the predictor trained with population data are <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>{</mo><mn>6.96</mn><mrow><mo>[</mo><mn>4.87</mn><mo>,</mo><mn>8.67</mn><mo>]</mo></mrow></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>12.49</mn><mrow><mo>[</mo><mn>7.96</mn><mo>,</mo><mn>14.23</mn><mo>]</mo></mrow></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>19.52</mn><mrow><mo>[</mo><mn>10.62</mn><mo>,</mo><mn>23.37</mn><mo>]</mo></mrow></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>28.79</mn><mrow><mo>[</mo><mn>12.96</mn><mo>,</mo><mn>34.57</mn><mo>]</mo></mrow></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>32.3</mn><mrow><mo>[</mo><mn>16.20</mn><mo>,</mo><mn>41.59</mn><mo>]</mo></mrow></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>28.8</mn><mrow><mo>[</mo><mn>15.13</mn><mo>,</mo><mn>37.18</mn><mo>]</mo></mrow><mo>}</mo></mrow></semantics></math></inline-formula> mg/dL, for prediction horizons (PH) of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>{</mo><mn>15</mn><mo>,</mo><mn>30</mn><mo>,</mo><mn>60</mn><mo>,</mo><mn>120</mn><mo>,</mo><mn>180</mn><mo>,</mo><mn>240</mn><mo>}</mo></mrow></semantics></math></inline-formula> min, respectively, while the baseline of the individually trained RMSE results are <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>{</mo><mn>6.37</mn><mrow><mo>[</mo><mn>5.07</mn><mo>,</mo><mn>6.70</mn><mo>]</mo></mrow></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>11.27</mn><mrow><mo>[</mo><mn>8.35</mn><mo>,</mo><mn>12.65</mn><mo>]</mo></mrow></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>17.44</mn><mrow><mo>[</mo><mn>11.08</mn><mo>,</mo><mn>20.93</mn><mo>]</mo></mrow></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>22.72</mn><mrow><mo>[</mo><mn>14.29</mn><mo>,</mo><mn>28.19</mn><mo>]</mo></mrow></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>28.45</mn><mrow><mo>[</mo><mn>14.79</mn><mo>,</mo><mn>34.38</mn><mo>]</mo></mrow></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>25.58</mn><mrow><mo>[</mo><mn>13.10</mn><mo>,</mo><mn>36.60</mn><mo>]</mo></mrow><mo>}</mo></mrow></semantics></math></inline-formula> mg/dL, both training with 16 weeks of data. Results also show that the use of the population approach reduces the required training data by half, without losing any prediction capability.

Qais M. Al-Bataineh, Ahmad D. Telfah, Victoria Shpacovitch et al.

Imaging wide-field surface plasmon resonance (SPR) microscopy sensors based on polyacrylic acid polyelectrolyte brushes (PAA PEBs) were designed to enhance the sensitivity of nano-object detection. The switching behavior of the PAA PEBs against changes in the pH values was investigated by analyzing the chemical, morphological, optical, and electrical properties. At pH ~1, the brushes collapse on the surface with the dominance of carboxylic groups (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>COOH</mi></mrow></semantics></math></inline-formula>). Upon the increase in the pH to nine, the switching process completes, and the brushes swell from dissociating most of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>COOH</mi></mrow></semantics></math></inline-formula> groups and converting them into <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mi>COO</mi></mrow><mo>−</mo></msup></mrow></semantics></math></inline-formula> groups. The domination of the negatively charged <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mi>COO</mi></mrow><mo>−</mo></msup></mrow></semantics></math></inline-formula> groups increases the electrostatic repulsion in the polymer chains and stretches the brushes. The sensitivity of the SPR sensing device was investigated using a theoretical approach, as well as experimental measurements. The signal-to-noise ratio for a Au layer increases from six to eighteen after coating with PAA PEBs. In addition, the linewidth of the recorded image decreases from six pixels to five pixels by using the Au-PAA layers, which results from the enhanced spatial resolution of the recorded images. Coating a Au-layer with PAA PEBs enhances the sensitivity of the SPR sensing device, and improves the spatial resolution of the recorded image.

Ronald Marsiglia-Fuentes, Somaris E. Quintana, Luis A. García Zapateiro

Background: Hydrocolloids are ingredients used to improve the technological properties of products; currently, there is a growing demand from the food industry and consumers to use natural ingredients and reduce the environmental impact. Methods: This work evaluated the effect of pH on hydrocolloid extraction from the pulp, seed, and peel of mango (<i>Mangifera indica</i>) var. hilaza and their chemical, physicochemical, techno-functional, and structural properties. Results: The main component of the hydrocolloid was the carbohydrates for pulp (22.59%) and peel (24.05%), and the protein for seed (21.48%) was corroborated by NIR spectra and associated with the technological and functional properties. The solubility increases with the temperature presenting values higher than 75% at 80 °C; the swelling index was higher than 30%, while the water holding capacity was higher in samples with higher carbohydrate content (110–121%). Moreover, a higher content of total phenolic compounds (21.61 ± 0.39–51.77 ± 2.48 mg GAE/g) and antioxidant activity (≥193.82 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mi mathvariant="sans-serif">μ</mi><mi>Mol</mi><mo> </mo><mi>Trolox</mi></mrow><mo>/</mo><mi mathvariant="normal">g</mi></mrow></semantics></math></inline-formula>) was obtained. The pH of extraction changes the color parameters and microstructural properties. Conclusions: Novel ingredients from mango pulp, seed, and peel at different pH levels have technological and functional properties that are potential use in the food industry as an alternative to the development of microstructural products.

Bettina Kraft, Rebecca Achenbach, Horst-Michael Ludwig et al.

The cement industry gains increasing public attention because of the high CO₂ emissions for which it is accountable. One approach to improve the carbon footprint of cement production is the development of alternative binders, which can be produced with less energy consumption. These alternative binders have a reduced clinker to cement ratio or contain no Portland cement at all. For the corrosion protection of the reinforcement, the same requirements apply as for standardized types of cement. To perform this evaluation, a basic understanding is necessary of the products formed during hydration, the composition of the pore solutions and pore structure, and their influence on the resistance to carbonation. In this study, various alternative binders, such as novel types of composite cement with calcined clays or modified steel mill slag, alkali-activated materials, C<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mover><mi mathvariant="normal">S</mi><mo>¯</mo></mover></mrow></semantics></math></inline-formula>A cement, and a C-S-H binder, are presented. The conducted investigations at mortars and cement pastes show the differences in hydration, microstructure development, and pH. The changes in microstructure and phase assemblage due to carbonation and the suitability of carbonation testing at an elevated CO₂ content of 1 vol.-% for the different binders are also presented.

Florin Matusoiu, Adina Negrea, Mihaela Ciopec et al.

Aggressive industrial development over the last century involved different heavy metals being used, including high quantities of molybdenum, which need to be treated before discharge in industrial waters. Molybdenum’s market price and industrial applicability make its recovery a big challenge. In the present study the possibility to recover molybdenum ions from aqueous solutions by adsorption on a composite material based on silica matrix and iron oxides—SiO₂FexOy—was evaluated. Tests were performed in order to determine the influence of adsorbent material dose, initial solution pH, contact time and temperature over adsorption capacity of synthesized adsorbent material. For better understanding of the adsorption process, the obtained experimental data were modelled using Langmuir, Freundlich and Sips adsorption isotherms. Based on the obtained data, it can proved that the Sips isotherm was describing with better orderliness the studied process, obtaining a maximum adsorption capacity of 10.95 mg <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>MoO</mi></mrow><mn>4</mn><mrow><mn>2</mn><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula> for each gram of material. By modelling the studied adsorption process, it was proven that the pseudo-second order model is accurately describing the adsorption process. By fitting experimental data with Weber-Morris model, it was proven that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>MoO</mi></mrow><mn>4</mn><mrow><mn>2</mn><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula> adsorption is a complex process, occurring in two different steps, one controlled by diffusion and the second one controlled by mass transfer. Further, studies were performed in order to determine the optimum pH value needed to obtain maximum adsorption capacity, but also to determine which are the adsorbed species. From pH and desorption studies, it was proven that molybdate adsorption is a physical process. In order to establish the adsorption mechanism, the thermodynamic parameters (ΔG0, ΔH0 and ΔS0) were determined.

Pol Ribes-Pleguezuelo, Bruno Delacourt, Mika K. G. Holmberg et al.

The possible presence of life in the atmosphere of Venus has been debated frequently over the last 60 years. The discussion was recently reignited by the possible detection of phosphine (PH<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula>), but several other chemicals potentially relevant for life processes are also found in the middle atmosphere. Moreover, the reasons for the heterogeneous ultraviolet (UV) absorption between 320 and 400 nm in the altitude range ∼40–70 km are still not well understood. These aspects could be further studied in-situ by UV Raman and fluorescence instruments. Here, the conceptual design of a small balloon probe (<20 kg) is presented, including a science payload comprising a UV laser, spectrometer, and a telescope. The goal of the proposed mission is to analyse the absorption of UV light in Venus’ atmosphere, to study the atmospheric composition, and to verify the possible presence of biomarkers. Current state-of-the-art technologies would allow a more cost-efficient and easy to develop mission, as compared to previous Venus probes. This article is focused on the scientific instrumentation, as well as on the mass and power budgets required to realise the proposed mission.

C. A. Miller, C. A. Miller, C. Bonsell et al.

<p>The western Arctic Ocean, including its shelves and coastal habitats, has become a focus in ocean acidification research over the past decade as the colder waters of the region and the reduction of sea ice appear to promote the uptake of excess atmospheric <span class="inline-formula">CO₂</span>. Due to seasonal sea ice coverage, high-frequency monitoring of pH or other carbonate chemistry parameters is typically limited to infrequent ship-based transects during ice-free summers. This approach has failed to capture year-round nearshore carbonate chemistry dynamics which is modulated by biological metabolism in response to abundant allochthonous organic matter to the narrow shelf of the Beaufort Sea and adjacent regions. The coastline of the Beaufort Sea comprises a series of lagoons that account for <span class="inline-formula">&gt;</span> 50 % of the land–sea interface. The lagoon ecosystems are novel features that cycle between “open” and “closed” phases (i.e., ice-free and ice-covered, respectively). In this study, we collected high-frequency pH, salinity, temperature, and photosynthetically active radiation (PAR) measurements in association with the Beaufort Lagoon Ecosystems – Long Term Ecological Research program – for an entire calendar year in Kaktovik Lagoon, Alaska, USA, capturing two open-water phases and one closed phase. Hourly pH variability during the open-water phases are some of the fastest rates reported, exceeding 0.4 units. Baseline pH varied substantially between the open phase in 2018 and open phase in 2019 from <span class="inline-formula">∼</span> 7.85 to 8.05, respectively, despite similar hourly rates of change. Salinity–pH relationships were mixed during all three phases, displaying no correlation in the 2018 open phase, a negative correlation in the 2018/19 closed phase, and a positive correlation during the 2019 open phase. The high frequency of pH variability could partially be explained by photosynthesis–respiration cycles as correlation coefficients between daily average pH and PAR were 0.46 and 0.64 for 2018 and 2019 open phases, respectively. The estimated annual daily average <span class="inline-formula">CO₂</span> efflux (from sea to atmosphere) was 5.9 <span class="inline-formula">±</span> 19.3 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">mmol</mi><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">m</mi><mrow><mo>-</mo><mn mathvariant="normal">2</mn></mrow></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">d</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="67pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="5c8e9505131ab94282875fdeca20f34d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-18-1203-2021-ie00001.svg" width="67pt" height="13pt" src="bg-18-1203-2021-ie00001.png"/></svg:svg></span></span>, which is converse to the negative influx of <span class="inline-formula">CO₂</span> estimated for the coastal Beaufort Sea despite exhibiting extreme variability. Considering the geomorphic differences such as depth and enclosure in Beaufort Sea lagoons, further investigation is needed to assess whether there are periods of the open phase in which lagoons are sources of carbon to the atmosphere, potentially offsetting the predicted sink capacity of the greater Beaufort Sea.</p>

X. Chen, Ph. L. Toint

Ali Entezari-Zarandi, Dariush Azizi, Pavel Anatolyevich Nikolaychuk et al.

Selective solvent extraction of molybdenum over rhenium from molybdenite (MoS₂) flue dust leaching solution was studied. In the present work, thermodynamic calculations of the chemical equilibria in aqueous solution were first performed, and the potential–pH diagram for the Mo–Re–<inline-formula><math display="inline"><semantics><mrow><msubsup><mrow><mi>SO</mi></mrow><mn>4</mn><mrow><mn>2</mn><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula>–H₂O system was constructed. With the gained insight on the system, 2-ethylhexyl phosphonic acid mono-(2-ethylhexyl)-ester (PC88A) diluted in kerosene was used as the extractant agent. Keeping constant the reaction temperature and aqueous-to-organic phase ratio (1:1), organic phase concentration and pH were the studied experimental variables. It was observed that by increasing the acidity of the solution and extractant concentration, selectivity towards Mo extraction increased, while the opposite was true for Re extraction. Selective Mo removal (+95%) from leach solution containing ca. 9 g/L Mo and 0.5 g/L Re was achieved when using an organic phase of 5% PC88A at pH = 0. No rhenium was coextracted during 10 min of extraction time at room temperature. Density functional theory (DFT) calculations were performed in order to study the interactions of organic extractants with Mo and Re ions, permitting a direct comparison of calculation results with the experimental data to estimate selectivity factors in Mo–Re separation. For this aim, PC88A and D2EHPA (di-(2-ethylhexyl) phosphoric acid) were simulated. The interaction energies of D2EHPA were shown to be higher than those of PC88A, which could be due to its stronger capability for complex formation. Besides, it was found that the interaction energies of both extractants follow this trend considering Mo species: <inline-formula><math display="inline"><semantics><mrow><msubsup><mrow><mi>MoO</mi></mrow><mn>2</mn><mrow><mrow><mn>2</mn><mo>+</mo></mrow></mrow></msubsup></mrow></semantics></math></inline-formula> > <inline-formula><math display="inline"><semantics><mrow><msubsup><mrow><mi>MoO</mi></mrow><mn>4</mn><mrow><mn>2</mn><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula>. It was also demonstrated through DFT calculations that the interaction energies of D2EHPA and PC88A with species are based on these trends, respectively: <inline-formula><math display="inline"><semantics><mrow><msubsup><mrow><mi>MoO</mi></mrow><mn>2</mn><mrow><mrow><mn>2</mn><mo>+</mo></mrow></mrow></msubsup></mrow></semantics></math></inline-formula> > <inline-formula><math display="inline"><semantics><mrow><msubsup><mrow><mi>MoO</mi></mrow><mn>4</mn><mrow><mn>2</mn><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula> > <inline-formula><math display="inline"><semantics><mrow><msubsup><mrow><mi>ReO</mi></mrow><mn>4</mn><mo>−</mo></msubsup></mrow></semantics></math></inline-formula> and <inline-formula><math display="inline"><semantics><mrow><msubsup><mrow><mi>MoO</mi></mrow><mn>2</mn><mrow><mrow><mn>2</mn><mo>+</mo></mrow></mrow></msubsup></mrow></semantics></math></inline-formula> > <inline-formula><math display="inline"><semantics><mrow><msubsup><mrow><mi>ReO</mi></mrow><mn>4</mn><mo>−</mo></msubsup></mrow></semantics></math></inline-formula> > <inline-formula><math display="inline"><semantics><mrow><msubsup><mrow><mi>MoO</mi></mrow><mn>4</mn><mrow><mn>2</mn><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula>, in qualitative agreement with the experimental findings.

S B AHER, BRIJ LAL LAKARIA, A B SINGH et al.

A field experiment was conducted at the Research Farm of ICAR-Indian Institute of Soil Science, Bhopal, India to study the effect of different combinations of organic inputs on performance of soybean [Glycine max (L.) Merr.]. Soybean (cv. JS 335) was grown in a randomized block design with seven treatments and four replications. The treatments studied were organic manure (OM) (T1); biodynamic preparation (BD) (T2); OM+panchagavya (OM+PG) (T3); OM+BD (T4); OM+PG+BD (T5); control (T6); and recommended dose of fertilizers (RDF) (T7). The results of the study revealed that, the treatments with organic manures either alone or in combination with panchagavya and/or biodynamic application improved the performance of soybean crop. The yield of soybean was found comparable and even better (higher 5–13%) with those obtained under RDF, which enhanced nutrient removal by soybean crop by 5–13% with organic combinations. Similarly, the application of organic manures significantly improved the available nutrient status of soil and showed 19–22% and 28–33% higher available N and P, respectively than RDF. Soil enzyme activities, viz. dehydrogenase and alkaline phosphatase increased by 62–72% and 27–35%, respectively under the treatments receiving organic source of nutrients over RDF.

Julia Hartwiger, Melanie Schären, Sarah Potthoff et al.

In spring, transition from a total mixed ration (TMR) to pasture requires rumen adaptions for the cow. It had been shown that transition period does not necessarily mean an increased risk for subacute ruminal acidosis (SARA). After adaption to pasture, however, supplying low amounts of concentrate did indicate increased risk, but caused no adverse effects on rumen morphology and absorption capacity. The present study aimed to investigate the effect of transition, and how a supply of 4.5 kg dry matter concentrate&#183;cow^&#8722;1<inline-formula> <math display="inline"> <semantics> <mo>&#183;</mo> </semantics> </math> </inline-formula>day^&#8722;1 during fulltime grazing influenced different rumen parameters. During a 12-week trial eleven rumen-cannulated dairy cows were observed during transition from confinement to pasture (PG; <i>n</i> = 6) and compared to cows fed TMR indoors (CG; <i>n</i> = 5). The CG stayed on a TMR based ration (35% corn silage, 35% grass silage, 30% concentrate; dry matter basis), whereas the PG slowly switched to a pasture-based ration (week 0 and 1 = TMR, week 2 = TMR and 3 h pasture&#183;day^&#8722;1, week 3 and 4 = TMR and 12 h pasture&#183;day^&#8722;1, and week 5 to 11 = pasture combined with 4.5 kg DM concentrate<inline-formula> <math display="inline"> <semantics> <mo>&#183;</mo> </semantics> </math> </inline-formula>cow^&#8722;1&#183;day^&#8722;1). Papillae surface area decreased during transition and increased again during fulltime grazing, while the fractional absorption rate of volatile fatty acids (VFA) was not influenced. This suggests only a limited effect of papillae surface area on VFA absorption rate. Feeding changes resulted in different fermentation profiles of VFA. Changing ratio of starch to sugar during transition to fulltime grazing plus concentrate supply did not lead to lower rumen pH. In conclusion, the concentrate supply combined with high fermentable grass during fulltime grazing increased papillae surface area but did not affect absorption rate or rumen pH, so that risk for SARA was not increased.

Sawyer R. Masonjones, Heather D. Masonjones, Megan C. Malone et al.

pH is an essential biological concept with critical importance at various scales, from the molecular level, dealing with blood buffers, homeostasis, and proton gradients, all the way up to the ecosystem level, with soil chemistry and acid rain. However, pH is also a concept that spawns student misconceptions and misunderstanding in terms of what is happening in a solution on the atomic level. The Molecular Twister game, created for a Florida Department of Education funded professional development workshop for Florida high school teachers hosted at the University of Tampa (Science Math Masters), seeks to model pH in such a way that students can visually and kinesthetically learn the concept in a few minutes. In addition, the basic design of the game pieces allow for teaching extensions to include more complex acid-base reactions. Challenge questions are provided to allow teachers to bring relevancy to the game, using examples of acid-base chemistry pulled from cases in human health and the environment.