Hasil untuk "math-ph"

Q. Zhang, Q. Zhang, W. Zhou et al.

<p>Benzothiazoles (BTs), widely used as vulcanization accelerators in the rubber industry, have frequently been identified in the atmosphere, especially in areas with heavy traffic. BTs can undergo gas-phase oxidation in the atmosphere, which contributes to secondary aerosol mass. However, given their certain water solubility, the atmospheric fate of BTs associated with aqueous-phase transformations is unclear. In this study, the reactions of benzothiazole (BT), 2-methylbenzothiazole (MBT), and 2-chlorobenzothiazole (CBT) with hydroxyl radicals (OH) were investigated. The rate constants of BT, MBT, and CBT reacted with OH radicals were determined to be (8.0 <span class="inline-formula">±</span> 1.8), (7.6 <span class="inline-formula">±</span> 1.7), and (7.6 <span class="inline-formula">±</span> 1.9) <span class="inline-formula">×</span> <span class="inline-formula">10⁹</span> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><msup><mi mathvariant="normal">M</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">s</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="39pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="eee7835944e18e58d5da835a15780d7a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-25-13475-2025-ie00001.svg" width="39pt" height="13pt" src="acp-25-13475-2025-ie00001.png"/></svg:svg></span></span> at initial pH 2 and (9.7 <span class="inline-formula">±</span> 2.7), (9.8 <span class="inline-formula">±</span> 2.7), and (9.4 <span class="inline-formula">±</span> 2.7) <span class="inline-formula">×</span> <span class="inline-formula">10⁹</span> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><msup><mi mathvariant="normal">M</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">s</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="39pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="521ddad889245f4e76fed273ba8a06e6"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-25-13475-2025-ie00002.svg" width="39pt" height="13pt" src="acp-25-13475-2025-ie00002.png"/></svg:svg></span></span> at initial pH 10, respectively. Lifetimes ranging from several minutes to several hours were estimated under mean OH concentrations in various atmospheric aqueous phases, which are significantly shorter than those estimated under mean OH concentrations in the gas phase. The nanoparticle tracing analysis (NTA) directly shows the formation of nanoparticles from the aqueous-phase photooxidation of the selected BTs. Data analysis of liquid chromatography Orbitrap mass spectrometry (LC-Orbitrap MS) identifies many multifunctional oligomers. Changes in optical property support the formation of oligomers and suggest that the products have the potential to contribute to the atmospheric brown carbon. In addition, higher yields of sulfate are formed after the reactions. It is highlighted that the aqueous-phase oxidation of BTs can contribute to the secondary aerosol mass in the ambient atmosphere, particularly in polluted regions where concentrations of BTs are comparable to those of benzenes, potentially altering the chemical composition and optical properties of atmospheric particles.</p>

Karen Simonyan, Astghik Tsokolakyan, Vahe Buniatyan et al.

A simplified kinetic model for the quantitative analysis of a potentiometric, pH-based urea biosensor is presented. The device was an electrolyte–insulator–semiconductor capacitor (EISCAP) with a pH-sensitive Ta₂O₅ gate functionalized by a polyallylamine hydrochloride (PAH)/urease bilayer. Within the steady-state approximation, the kinetic equations yielded an implicit algebraic relation linking the bulk urea concentration to the local pH at the sensor surface. Numerical solution of this equation, combined with a fitting routine, provides the apparent Michaelis–Menten constant (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>K</mi><mi>M</mi></msub></mrow></semantics></math></inline-formula>) and the normalized maximum reaction rate (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mover accent="true"><mi>k</mi><mo>¯</mo></mover><mi>V</mi></msub></mrow></semantics></math></inline-formula>). Validation against the literature data confirmed the reliability of the approach. Experimental results were then analyzed in both phosphate buffer (PBS) and artificial urine (AU), covering urea concentrations of 0.1–50 mM. The fitted parameters showed comparable <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>K</mi><mi>M</mi></msub></mrow></semantics></math></inline-formula> values of 10.9 mM (PBS) and 32.4 mM (AU), but strongly different <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mover accent="true"><mi>k</mi><mo>¯</mo></mover><mi>V</mi></msub></mrow></semantics></math></inline-formula> values: <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2.2</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></semantics></math></inline-formula> (PBS) versus <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>8.6</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>7</mn></mrow></msup></mrow></semantics></math></inline-formula> (AU). The three-order reduction in AU was attributed to the inhibitory effects inherent to complex biological fluids. These findings highlight the importance of the model-based quantitative analysis of EISCAP biosensors, enabling the accurate characterization of immobilized enzyme layers and guiding optimization for applications in realistic sample matrices.

Shan Gao

Based on a power supply system, a repairable K-out-of-<inline-formula> <tex-math notation="LaTeX">$N+W$ </tex-math></inline-formula>: G system with c repairmen and warm spares is considered, where each repairman asynchronously takes multiple working vacations and vacation interruption policy. Total load of the system is shared equally by all the operating generators, the failure rate of each operating generator increases with the decreasing of the number of operating generators. Using Markov process and matrix-analytic method, steady-state probabilities and important performance indices are obtained. The mean time to first failure and reliability function are given by using the definition of PH-distribution. Numerical examples are given to illustrate the effect of system parameters on these reliability indices. In addition, machine learning (ML) methods including decision tree regression (DTR), random forest regression (RFR) and multilayer perceptron regression (MLPR) are used to predict the steady-state availability of the system, which shows that RFR is the optimal prediction model, and feature importances of system parameters are also provided.

X. Zhang, X. Zhang, L. Wang et al.

<p>HONO plays a crucial role as a precursor to <span class="inline-formula">OH</span> radicals in the tropospheric atmosphere. The incongruity between HONO concentration and <span class="inline-formula">NO_<i>x</i></span> emissions during the COVID-19 pandemic remains puzzling. Here, we show evidence from field observations of 10 sites in China where there was a noticeable increase in <span class="inline-formula">NH₃</span> concentrations during the COVID-19 pandemic. In addition to the meteorological conditions, the significant decrease in sulfate and nitrate concentrations enhanced the conversion of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NH</mi><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="dd01b19a584d9ff35339d41174090f98"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-9885-2024-ie00001.svg" width="24pt" height="15pt" src="acp-24-9885-2024-ie00001.png"/></svg:svg></span></span> to <span class="inline-formula">NH₃</span>. Sensitivity analysis indicated that the decrease in anion concentrations (especially sulfate and nitrate) and the increase in cation concentrations during the COVID-19 pandemic led to an increase in particle pH. In other words, changes in the excess ammonia drove changes in particle pH that may consequently have impacted the rate of HONO formation. The calculation of reaction rates indicates that during the epidemic, the increase in pH may promote the generation of HONO by facilitating redox reactions, which highlights the importance of coordinating the control of <span class="inline-formula">SO₂</span>, <span class="inline-formula">NO_<i>x</i></span>, and <span class="inline-formula">NH₃</span> emissions.</p>

Ibargüengoitia Martha Elena

We present an experimental activity designed for upper secondary students, where a pH scale is constructed taking advantage of the ability of a pH indicator to display different colors according to the pH of the medium. To build the scale, two solutions are prepared: 1 M HCl (pH = 0) and 1 M NaOH (pH = 14). Each original solution undergoes six consecutive 1/10 dilutions, producing acidic solutions with pH values of 1, 2, 3, 4, 5, and 6; and basic solutions with pH values of 13, 12, 11, 10, 9, and 8. Pure water (nominal pH = 7) serves as the reference. Upon adding the indicator, a beautiful rainbow of colors appears in the solution containers. To connect the experimental results with its mathematical representation, a written exercise is provided for students. This activity allows them to visually understand that, even though the change in pH is only one unit, the change in H+ concentration is 10 times greater or smaller. Thus, pH is an exponential function, best expressed in logarithmic terms.

Marvin Anker, Abdolrahim Yousefi-Darani, Viktoria Zettel et al.

Sourdough can improve bakery products’ shelf life, sensory properties, and nutrient composition. To ensure high-quality sourdough, the fermentation has to be monitored. The characteristic process variables for sourdough fermentation are pH and the degree of acidity measured as total titratable acidity (TTA). The time- and cost-intensive offline measurement of process variables can be improved by utilizing online gas measurements in prediction models. Therefore, a gas sensor array (GSA) system was used to monitor the fermentation process of sourdough online by correlation of exhaust gas data with offline measurement values of the process variables. Three methods were tested to utilize the extracted features from GSA to create the models. The most robust prediction models were achieved using a PCA (Principal Component Analysis) on all features and combined two fermentations. The calibrations with the extracted features had a percentage root mean square error (RMSE) from 1.4% to 12% for the pH and from 2.7% to 9.3% for the TTA. The coefficient of determination (<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>) for these calibrations was 0.94 to 0.998 for the pH and 0.947 to 0.994 for the TTA. The obtained results indicate that the online measurement of exhaust gas from sourdough fermentations with gas sensor arrays can be a cheap and efficient application to predict pH and TTA.

Shudong Yuan, Bei Sun, Zhen Zuo et al.

With the rapid growth of the global drone market, a variety of small drones have posed a certain threat to public safety. Therefore, we need to detect small drones in a timely manner so as to take effective countermeasures. At present, the method based on deep learning has made a great breakthrough in the field of target detection, but it is not good at detecting small drones. In order to solve the above problems, we proposed the IRSDD-YOLOv5 model, which is based on the current advanced detector YOLOv5. Firstly, in the feature extraction stage, we designed an infrared small target detection module (IRSTDM) suitable for the infrared recognition of small drones, which extracted and retained the target details to allow IRSDD-YOLOv5 to effectively detect small targets. Secondly, in the target prediction stage, we used the small target prediction head (PH) to complete the prediction of the prior information output via the infrared small target detection module (IRSTDM). We optimized the loss function by calculating the distance between the true box and the predicted box to improve the detection performance of the algorithm. In addition, we constructed a single-frame infrared drone detection dataset (SIDD), annotated at pixel level, and published an SIDD dataset publicly. According to some real scenes of drone invasion, we divided four scenes in the dataset: the city, sky, mountain and sea. We used mainstream instance segmentation algorithms (Blendmask, BoxInst, etc.) to train and evaluate the performances of the four parts of the dataset, respectively. The experimental results show that the proposed algorithm demonstrates good performance. The <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>A</mi><msub><mi>P</mi><mrow><mn>50</mn></mrow></msub></mrow></semantics></math></inline-formula> measurements of IRSDD-YOLOv5 in the mountain scene and ocean scene reached peak values of 79.8% and 93.4%, respectively, which are increases of 3.8% and 4% compared with YOLOv5. We also made a theoretical analysis of the detection accuracy of different scenarios in the dataset.

Zongyong Tong, Lixue Wang, Yu Wang et al.

Alfalfa (<i>Medicago sativa</i> L.) and corn (<i>Zea mays</i> L.) are common forage plants for feeding livestock, and their effects on soil bacterial organisms have been extensively studied. However, there is little comprehensive research on soil bacterial organisms and their function in a long-term alfalfa monocropping system after corn insertion and fertilization. The effects of alfalfa–corn rotation (AF: alfalfa monocropping, RA: alfalfa and corn rotation) and nitrogen fertilization (RA0 and RA15) were investigated in a field experiment. The results showed that fertilization significantly increased the aboveground biomass (AGB) and soil nitrate nitrogen, and corn insertion significantly decreased the nitrate nitrogen (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>NO</mi></mrow><mn>3</mn><mo>−</mo></msubsup></mrow></semantics></math></inline-formula>-N) (<i>p</i> < 0.05). In addition, the bacterial community structure among the treatments was significantly changed by the rotation and fertilization. The rotational system of RA significantly increased the soil bacterial diversity compared with AF (<i>p</i> < 0.01), and most of the soil bacterial communities were of the phyla Actinobacterota and Proteobacteria. The RA system had a lower relative abundance of Actinobacterota than the AF system. The bacterial function prediction found that the soil carbon and nitrogen cycle processes in RA were more active than those in AF. The RDA analysis revealed that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi>NO</mi></mrow><mn>3</mn><mo>−</mo></msubsup></mrow></semantics></math></inline-formula>-N and pH were the main environmental factors affecting the bacterial community structure in the RA system.

Yuqi Chen, Richard Compton

A bespoke calibration-free pH sensor using an in situ modified Ir electrode for applications in seawater is reported. The electrochemical behaviour of an iridium wire in air-saturated synthetic seawater was studied and the formation of pH-sensitive surface layers was observed that featured three pH-sensitive redox couples, Ir(III/IV), <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>IrO</mi></mrow><mi mathvariant="normal">x</mi></msub><msup><mi mathvariant="normal">O</mi><mrow><mi mathvariant="normal">I</mi><mo>−</mo></mrow></msup><mo>/</mo><msub><mrow><mi>IrO</mi></mrow><mi mathvariant="normal">x</mi></msub><msup><mi mathvariant="normal">O</mi><mrow><mi>II</mi><mo>−</mo></mrow></msup><mi mathvariant="normal">H</mi><mo>,</mo></mrow></semantics></math></inline-formula> and H_upd/H⁺, where H_upd is adsorbed hydrogen deposited at underpotential conditions. The amperometric properties of the electrochemically activated Ir wire were investigated using linear sweep voltammetry first, followed, second, by square wave voltammetry with the formation conditions in seawater for the optimal pH sensitivity of the redox couples identified. The sensor was designed to be calibration-free by measuring the “super-Nernstian” response, in excess of ca 60 mV per pH unit, of Ir(III/IV) relative to the less sensitive upd H oxidation signal with the pH reported on the total pH scale. The pH dependency of the optimised sensor was 70.1 ± 1.4 mV per pH unit at 25 °C, showing a super-Nernstian response of high sensitivity.

Ibrahim Elbatal, Sadaf Khan, Tassaddaq Hussain et al.

With the aim of identifying a probability model that not only correctly describes the stochastic behavior of extreme environmental factors such as excess rain, acid rain pH level, and concentrations of ozone, but also measures concentrations of NO<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula> and leads deliberations, etc., for a specific site or multiple site forms as well as for life testing experiments, we introduced a novel class of distributions known as the Sine Burr <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="script">X</mi><mo>−</mo><mi mathvariant="script">G</mi></mrow></semantics></math></inline-formula> family. Some exceptional prototypes of this class are proposed. Statistical assets of the presented class, such as density function, complete and incomplete moments, average deviation, and Lorenz and Bonferroni graphs, are proposed. Parameter estimation is made via the likelihood method. Moreover, the application is explained by using four real data sets. We have also illustrated the significance and elasticity of the proposed class in the above-mentioned stochastic phenomenon.

Dengshan Li, Lina Li

pH is an important parameter for water quality detection. This study proposed a novel calibration regression strategy based on a one-dimensional convolutional neural network (1D-CNN) for water pH detection using visible near-infrared (Vis-NIR) spectroscopy. Two groups of Vis-NIR spectral analysis experiments of water pH detection were employed to evaluate the performance of 1D-CNN. Two conventional multivariate regression calibration methods, including partial least squares (PLS) and least squares support vector machine (LS-SVM), were introduced for comparative analysis with 1D-CNN. The successive projections algorithm (SPA) was adopted to select the feature variables. In addition, the learning mechanism of 1D-CNN was interpreted through visual feature maps by convolutional layers. The results showed that the 1D-CNN models obtained the highest prediction accuracy based on full spectra for the two experiments. For the spectrophotometer experiment, the root mean square error of prediction (RMSEP) was 0.7925, and the determination coefficient of prediction (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mi>R</mi><mi>p</mi><mn>2</mn></msubsup></mrow></semantics></math></inline-formula>) was 0.8515. For the grating spectrograph experiment, the RMSEP was 0.5128 and the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mi>R</mi><mi>p</mi><mn>2</mn></msubsup></mrow></semantics></math></inline-formula> was 0.9273. The convolutional layers could automatically preprocess the spectra and effectively extract the spectra features. Compared with the traditional regression methods, 1D-CNN does not need complex spectra pretreatment and variable selection. Therefore, 1D-CNN is a promising regression approach, with higher prediction accuracy and better modeling convenience for rapid water pH detection using Vis-NIR spectroscopy.

Fen Tang, Qingqing Shang, Songlin Yang et al.

The photonic hook (PH) is a new type of curved light beam, which has promising applications in various fields such as nanoparticle manipulation, super-resolution imaging, and so forth. Herein, we proposed a new approach of utilizing patchy microcylinders for the generation of PHs. Numerical simulation based on the finite-difference time-domain method was used to investigate the field distribution characteristics of the PHs. By rotating the patchy microcylinder, PHs with different curvatures can be effectively generated, and the PH with a bending angle of 28.4<inline-formula><math display="inline"><semantics><msup><mrow></mrow><mo>∘</mo></msup></semantics></math></inline-formula> and a full-width-half-maximum of 0.36 <inline-formula><math display="inline"><semantics><mi>λ</mi></semantics></math></inline-formula> can be obtained from 1 <inline-formula><math display="inline"><semantics><mi mathvariant="sans-serif">μ</mi></semantics></math></inline-formula>m-diameter patchy microcylinders.

M. Lu, D. S. Powlson, D. S. Powlson et al.

<p>Within the context of sustainable development, soil degradation driven by land use change is considered a serious global problem, but the conversion from growing cereals to vegetables is a change that has received limited attention, especially in subtropical regions. Here, we studied the effects of the conversion from paddy rice to an oilseed rape rotation to vegetable production in southwestern China on soil organic carbon (SOC), total nitrogen (TN), the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">C</mi><mo>/</mo><mi mathvariant="normal">N</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="f135772273124e8de131c1d3d27c70de"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-7-333-2021-ie00001.svg" width="24pt" height="14pt" src="soil-7-333-2021-ie00001.png"/></svg:svg></span></span> ratio, pH, phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) based on face-to-face farmer surveys and soil analysis. In the vegetable cropping system, fertilizer application often exceeds the crop demand or levels recommended by the local extension service several times over. Thus, the crop use efficiency of N, P, K, Ca, and Mg was only 26 %, 8 %, 56 %, 23 %, and 28 %, respectively. In the vegetable cropping system studied, SOC, C stock, TN, and N stock were decreased significantly due to low organic inputs from crop residues and high tillage frequency. Furthermore, the soil <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">C</mi><mo>/</mo><mi mathvariant="normal">N</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="de4c857a5316d0d8e75c5f4965b9bc96"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-7-333-2021-ie00002.svg" width="24pt" height="14pt" src="soil-7-333-2021-ie00002.png"/></svg:svg></span></span> ratio decreased slightly; available P (AP) in the topsoil increased by 1.92 mg kg<span class="inline-formula">⁻¹</span> for every 100 kg ha<span class="inline-formula">⁻¹</span> of P surplus, and the critical levels of AP and CaCl<span class="inline-formula">₂</span>-soluble P in P leaching were 104 and 0.80 mg P kg<span class="inline-formula">⁻¹</span>. Besides, compared to the current paddy–rape rotation system, a clear trend of soil acidification was observed in the vegetable fields. However, increasing the contents of soil Ca and Mg significantly alleviated topsoil acidification, with the effect increasing over time. Given our findings, the potential benefits of conservation agricultural practices, integrated soil–crop system management strategies, and agricultural technology services for recovering the degraded soil and improving the vegetable productivity are discussed here.</p>

M. Roy-Barman, L. Foliot, E. Douville et al.

<p>Lithogenic elements such as aluminum (Al), iron (Fe), rare earth elements (REEs), thorium (<span class="inline-formula">²³²Th</span> and <span class="inline-formula">²³⁰Th</span>, given as Th) and protactinium (Pa) are often assumed to be insoluble. In this study, their dissolution from Saharan dust reaching Mediterranean seawater was studied through tank experiments over 3 to 4 d under controlled conditions including controls without dust addition as well as dust seeding under present and future climate conditions (<span class="inline-formula">+3</span> <span class="inline-formula">^∘C</span> and <span class="inline-formula">−0.3</span> pH). Unfiltered surface seawater from three oligotrophic regions (Tyrrhenian Sea, Ionian Sea and Algerian Basin) were used. The maximum dissolution was low for all seeding experiments: less than 0.3 % for Fe, 1 % for <span class="inline-formula">²³²Th</span> and Al, about 2 %–5 % for REEs and less than 6 % for Pa. Different behaviors were observed: dissolved Al increased until the end of the experiments, Fe did not dissolve significantly, and Th and light REEs were scavenged back on particles after a fast initial release. The constant <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msup><mi/><mn mathvariant="normal">230</mn></msup><mi mathvariant="normal">Th</mi><msup><mo>/</mo><mn mathvariant="normal">232</mn></msup><mi mathvariant="normal">Th</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="61pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="c9737dd2eaac67c6418a5cd8a6debca4"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-18-2663-2021-ie00001.svg" width="61pt" height="15pt" src="bg-18-2663-2021-ie00001.png"/></svg:svg></span></span> ratio during the scavenging phase suggests that there is little or no further dissolution after the initial Th release. Quite unexpectedly, comparison of present and future conditions indicates that changes in temperature and/or pH influence the release of Th and REEs in seawater, leading to lower Th release and a higher light REE release under increased greenhouse conditions.</p>

C. Feller, U. Partsch

<p>Ion-selective electrodes (ISEs) have been proven particularly useful in water analysis. They are usually used as single-rod measuring chains in different designs, which are manufactured using precision mechanical manufacturing and assembling technologies. The paper describes a microsystem technology approach for the fabrication of miniaturized electrochemical sensors. The ceramic HTCC (high-temperature co-fired ceramic) and LTCC (low-temperature co-fired ceramic) multilayer technology enables suitable processes for the manufacturing of robust and miniaturized sensor arrays with a high functional density. Design, manufacture, and electrochemical performance of the novel ceramic multilayer-based sensor array are presented in the paper using various examples. An adapted material and process development was carried out for the sensitive functional films. Special thick-film pastes for the detection of the pH value as well as <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NH</mi><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="8aeb386a576ed6c8280ae774099f80e4"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jsss-10-83-2021-ie00001.svg" width="24pt" height="15pt" src="jsss-10-83-2021-ie00001.png"/></svg:svg></span></span>, <span class="inline-formula">K⁺</span>, <span class="inline-formula">Ca²⁺</span>, and <span class="inline-formula">Cu²⁺</span> ion concentrations in aqueous solutions were developed. Ion-sensitive thick-film membranes were deposited on a ceramic multilayer sensor platform by means of screen-printing. All ISEs, integrated in the sensor array, showed suitable electrochemical performances including a very quick response (several seconds) combined with a high sensitivity (exhibiting Nernstian behaviour) in the tested measuring range. The obtained sensitivities were around 57 <span class="inline-formula">mVper decade</span>: for the pH sensor, 30 <span class="inline-formula">mVper decade</span> for calcium, 53 <span class="inline-formula">mVper decade</span> for potassium, and 57 <span class="inline-formula">mVper decade</span> for ammonium. Depending on the application, different sensitive electrodes on the ceramic sensor array can be combined as required.</p>

Isabelle Cattiaux-Huillard, Laura Saini

Roger Monreal-Corona, Jesse Biddlecombe, Angela Ippolito et al.

The thermodynamic stability of twenty-nine Fe(III) complexes with various deprotonated forms of lipoic (LA) and dihydrolipoic (DHLA) acids, with coordination numbers 4, 5 and 6, is studied at the M06(SMD)/6-31++G(d,p) level of theory in water under physiological pH conditions at 298.15 K. Even though the complexes with LA^- are more stable than those with DHLA⁻, the most thermodynamically stable Fe(III) complexes involve DHLA²⁻. The twenty-four exergonic complexes are used to evaluate the secondary antioxidant activity of DHLA and LA relative to the Fe(III)/Fe(II) reduction by <inline-formula><math display="inline"><semantics><mrow><msubsup><mi mathvariant="normal">O</mi><mn>2</mn><mrow><mo>•</mo><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula> and ascorbate. Rate constants for the single-electron transfer (SET) reactions are calculated. The thermodynamic stability of the Fe(III) complexes does not fully correlate with the rate constant of their SET reactions, but more exergonic complexes usually exhibit smaller SET rate constants. Some Cu(II) complexes and their reduction to Cu(I) are also studied at the same level of theory for comparison. The Fe(III) complexes appear to be more stable than their Cu(II) counterparts. Relative to the Fe(III)/Fe(II) reduction with ascorbate, DHLA can fully inhibit the formation of ^•OH radicals, but not by reaction with <inline-formula><math display="inline"><semantics><mrow><msubsup><mi mathvariant="normal">O</mi><mn>2</mn><mrow><mo>•</mo><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula>. Relative to the Cu(II)/Cu(I) reduction with ascorbate, the effects of DHLA are moderate/high, and with <inline-formula><math display="inline"><semantics><mrow><msubsup><mi mathvariant="normal">O</mi><mn>2</mn><mrow><mo>•</mo><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula> they are minor. LA has minor to negligible inhibition effects in all the cases considered.

T. Amann, J. Hartmann, E. Struyf et al.

<p>The weathering of silicates is a major control on atmospheric <span class="inline-formula">CO₂</span> at geologic timescales. It was proposed to enhance this process to actively remove <span class="inline-formula">CO₂</span> from the atmosphere. While there are some studies that propose and theoretically analyze the application of rock powder to agricultural land, results from field experiments are still scarce.</p> <p>In order to evaluate the efficiency and side effects of Enhanced Weathering (EW), a mesocosm experiment was set up and agricultural soil from Belgium was amended with olivine-bearing dunite ground to two different grain sizes, while distinguishing setups with and without crops.</p> <p>Based on measurements of Mg, Si, pH, and DIC, the additional weathering effect of olivine could be confirmed. Calculated weathering rates are up to 3 orders of magnitude lower than found in other studies. The calculated <span class="inline-formula">CO₂</span> consumption by weathering based on the outlet water of the mesocosm systems was low with 2.3–4.9&thinsp;<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">t</mi><mspace width="0.125em" linebreak="nobreak"/><msub><mi mathvariant="normal">CO</mi><mn mathvariant="normal">2</mn></msub><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">km</mi><mrow><mo>-</mo><mn mathvariant="normal">2</mn></mrow></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">a</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="72pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="ef5dfbca643d1c7c552e0008bc662989"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-17-103-2020-ie00001.svg" width="72pt" height="16pt" src="bg-17-103-2020-ie00001.png"/></svg:svg></span></span> if compared with previous theoretical estimates. Suspected causes were the removal or dilution of Mg as a weathering product by processes like adsorption, mineralization, plant uptake, evapotranspiration, and/or preferential flow, not specifically addressed in previous EW experiments for <span class="inline-formula">CO₂</span> consumption. The observation that Mg concentrations in the upper soil layers were about 1 order of magnitude higher than in the outlet water indicates that a careful tracking of weathering indicators like Mg in the field is essential for a precise estimate of the <span class="inline-formula">CO₂</span> consumption potential of EW, specifically under global deployment scenarios with a high diversity of ecosystem settings. Porewater <span class="inline-formula">Mg∕Si</span> molar ratios suggest that dissolved Si is reprecipitating, forming a cation-depleted Si layer on the reactive mineral surface of freshly ground rocks.</p> <p>The release of potentially harmful trace elements is an acknowledged side effect of EW. Primarily Ni and Cr are elevated in the soil solution, while Ni concentrations exceed the limits of drinking water quality. The use of olivine, rich in Ni and Cr, is not recommended, and alternative rock sources are suggested for the application.</p>

G. Ciarelli, G. Ciarelli, G. Ciarelli et al.

<p>In the framework of the EURODELTA-Trends (EDT) modeling experiment, several chemical transport models (CTMs) were applied for the 1990–2010 period to investigate air quality changes in Europe as well as the capability of the models to reproduce observed long-term air quality trends. Five CTMs have provided modeled air quality data for 21 continuous years in Europe using emission scenarios prepared by the International Institute for Applied Systems Analysis/Greenhouse Gas – Air Pollution Interactions and Synergies (IIASA/GAINS) and corresponding year-by-year meteorology derived from ERA-Interim global reanalysis. For this study, long-term observations of particle sulfate (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">SO</mi><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="29pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="43c7521f547bc9d1c731092871dcc89b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gmd-12-4923-2019-ie00001.svg" width="29pt" height="17pt" src="gmd-12-4923-2019-ie00001.png"/></svg:svg></span></span>), total nitrate (<span class="inline-formula">TNO₃</span>), total ammonium (<span class="inline-formula">TNH_<i>x</i></span>) as well as sulfur dioxide (<span class="inline-formula">SO₂</span>) and nitrogen dioxide (<span class="inline-formula">NO₂</span>) for multiple sites in Europe were used to evaluate the model results. The trend analysis was performed for the full 21 years<span id="page4924"/> (referred to as PT) but also for two 11-year subperiods: 1990–2000 (referred to as P1) and 2000–2010 (referred to as P2).</p> <p>The experiment revealed that the models were able to reproduce the faster decline in observed <span class="inline-formula">SO₂</span> concentrations during the first decade, i.e., 1990–2000, with a 64&thinsp;%–76&thinsp;% mean relative reduction in <span class="inline-formula">SO₂</span> concentrations indicated by the EDT experiment (range of all the models) versus an 82&thinsp;% mean relative reduction in observed concentrations. During the second decade (P2), the models estimated a mean relative reduction in <span class="inline-formula">SO₂</span> concentrations of about 34&thinsp;%–54&thinsp;%, which was also in line with that observed (47&thinsp;%). Comparisons of observed and modeled <span class="inline-formula">NO₂</span> trends revealed a mean relative decrease of 25&thinsp;% and between 19&thinsp;% and 23&thinsp;% (range of all the models) during the P1 period, and 12&thinsp;% and between 22&thinsp;% and 26&thinsp;% (range of all the models) during the P2 period, respectively.</p> <p>Comparisons of observed and modeled trends in <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">SO</mi><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="29pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="8c898138530c760447165fe6cdc920bb"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gmd-12-4923-2019-ie00002.svg" width="29pt" height="17pt" src="gmd-12-4923-2019-ie00002.png"/></svg:svg></span></span> concentrations during the P1 period indicated that the models were able to reproduce the observed trends at most of the sites, with a 42&thinsp;%–54&thinsp;% mean relative reduction indicated by the EDT experiment (range of all models) versus a 57&thinsp;% mean relative reduction in observed concentrations and with good performance also during the P2 and PT periods, even though all the models overpredicted the number of statistically significant decreasing trends during the P2 period. Moreover, especially during the P1 period, both modeled and observational data indicated smaller reductions in <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">SO</mi><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="29pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="815783a157bc15e547bdd7a24388d96b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gmd-12-4923-2019-ie00003.svg" width="29pt" height="17pt" src="gmd-12-4923-2019-ie00003.png"/></svg:svg></span></span> concentrations compared with their gas-phase precursor (i.e., <span class="inline-formula">SO₂</span>), which could be mainly attributed to increased oxidant levels and pH-dependent cloud chemistry.</p> <p>An analysis of the trends in <span class="inline-formula">TNO₃</span> concentrations indicated a 28&thinsp;%–39&thinsp;% and 29&thinsp;% mean relative reduction in <span class="inline-formula">TNO₃</span> concentrations for the full period for model data (range of all the models) and observations, respectively. Further analysis of the trends in modeled <span class="inline-formula">HNO₃</span> and particle nitrate (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M16" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="48a6d5724cc017ced9c974ab9a81c03a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gmd-12-4923-2019-ie00004.svg" width="25pt" height="16pt" src="gmd-12-4923-2019-ie00004.png"/></svg:svg></span></span>) concentrations revealed that the relative reduction in <span class="inline-formula">HNO₃</span> was larger than that for <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M18" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="7dd3c683c0655cd2a5c1ed2d08ea01e9"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gmd-12-4923-2019-ie00005.svg" width="25pt" height="16pt" src="gmd-12-4923-2019-ie00005.png"/></svg:svg></span></span> during the P1 period, which was mainly attributed to an increased availability of “free ammonia”. By contrast, trends in modeled <span class="inline-formula">HNO₃</span> and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M20" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="827b0fe0e97f70953101fc9e20cd0031"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gmd-12-4923-2019-ie00006.svg" width="25pt" height="16pt" src="gmd-12-4923-2019-ie00006.png"/></svg:svg></span></span> concentrations were more comparable during the P2 period. Also, trends of <span class="inline-formula">TNH_<i>x</i></span> concentrations were, in general, underpredicted by all models, with worse performance for the P1 period than for P2.</p> <p>Trends in modeled anthropogenic and biogenic secondary organic aerosol (ASOA and BSOA) concentrations together with the trends in available emissions of biogenic volatile organic compounds (BVOCs) were also investigated. A strong decrease in ASOA was indicated by all the models, following the reduction in anthropogenic non-methane VOC (NMVOC) precursors. Biogenic emission data provided by the modeling teams indicated a few areas with statistically significant increase in isoprene emissions and monoterpene emissions during the 1990–2010 period over Fennoscandia and eastern European regions (i.e., around 14&thinsp;%–27&thinsp;%), which was mainly attributed to the increase of surface temperature. However, the modeled BSOA concentrations did not linearly follow the increase in biogenic emissions. Finally, a comprehensive evaluation against positive matrix factorization (PMF) data, available during the second period (P2) at various European sites, revealed a systematic underestimation of the modeled SOA fractions of a factor of 3 to 11, on average, most likely because of missing SOA precursors and formation pathways, with reduced biases for the models that accounted for chemical aging of semi-volatile SOA components in the atmosphere.</p>

Y. Kuzyakov, Y. Kuzyakov, K. Zamanian

<p>Agricultural land covers <span class="inline-formula">5.1×10⁹</span>&thinsp;ha (ca. 50&thinsp;% of potentially suitable land area), and agriculture has immense effects on soil formation and degradation. Although we have an advanced mechanistic understanding of individual degradation processes of soils under agricultural use, general concepts of agropedogenesis are absent. A unifying theory of soil development under agricultural practices, of agropedogenesis, is urgently needed. We introduce a theory of anthropedogenesis – soil development under the main factor “humankind” – the sixth factor of soil formation, and deepen it to encompass agropedogenesis as the most important direction of anthropedogenesis. The developed theory of agropedogenesis consists of (1) broadening the classical concept of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><mtext>factors</mtext><mo>→</mo><mtext>processes</mtext><mo>→</mo><mtext>properties</mtext><mo>→</mo><mtext>functions</mtext></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="226pt" height="12pt" class="svg-formula" dspmath="mathimg" md5hash="b003bd8c22036a899806f3db1ea290fb"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-16-4783-2019-ie00001.svg" width="226pt" height="12pt" src="bg-16-4783-2019-ie00001.png"/></svg:svg></span></span> along with their feedbacks to the processes, (2) a new concept of attractors of soil degradation, (3) selection and analysis of master soil properties, (4) analysis of phase diagrams of master soil properties to identify thresholds and stages of soil degradation, and, finally, (5) a definition of the multidimensional attractor space of agropedogenesis. The main feature of anthropedogenesis is the narrowing of soil development to only one function (e.g. crop production for agropedogenesis), and this function is becoming the main soil-forming factor. The focus on only one function and the disregard of other functions inevitably lead to soil degradation. We show that the factor humankind dominates over the effects of the five natural soil-forming factors and that agropedogenesis is therefore much faster than natural soil formation. The direction of agropedogenesis is largely opposite to that of natural soil development and is thus usually associated with soil degradation. In contrast to natural pedogenesis leading to <i>divergence</i> of soil properties, agropedogenesis leads to their <i>convergence</i> because of the efforts to optimize conditions for crop production. Agricultural practices lead soil development toward a quasi-steady state with a predefined range of measured properties – attractors (an attractor is a minimal or maximal value of a soil property toward which the property will develop via long-term intensive agricultural use from any natural state). Based on phase diagrams and expert knowledge, we define a set of “master properties” (bulk density and macroaggregates, soil organic matter content, <span class="inline-formula">C:N</span> ratio, pH and electrical conductivity – EC, microbial biomass and basal respiration) as well as soil depth (A and B horizons). These master properties are especially sensitive to land use and determine the other properties during agropedogenesis. Phase diagrams of master soil properties help identify thresholds and stages of soil degradation, each of which is characterized by one dominating process. Combining individual attractors in a multidimensional attractor space enables predicting the trajectory and the final state of agrogenic soil development and developing measures to combat soil degradation. In conclusion, the suggested new theory of anthro- and agropedogenesis is a prerequisite for merging various degradation processes into a general view and for understanding the functions of humankind not only as the sixth soil-forming factor but also as an ecosystem engineer optimizing its environment to fulfil a few desired functions.</p>