Hasil untuk "math-ph"

Jimin Ren, Neha Patel, Ross Querry et al.

<b>Background/Objectives:</b> Dynamic changes in inorganic phosphate (Pi), phosphocreatine (PCr), and pH during post-exercise recovery reflect underlying muscle energetics and mitochondrial ATP synthesis, but the conventional single-pool model assuming uniform metabolic response fails to address myofiber composition and pH-dependent metabolic heterogeneity in skeletal muscle. This study aimed to characterize the interplay between pH, Pi, and PCr, and to develop an analytical method for assessing pH-resolved ATP synthesis using ³¹P MRS. <b>Methods:</b> Five healthy subjects underwent dynamic ³¹P MRS scans during plantar flexion exercise. ATP synthesis was evaluated from post-exercise PCr and Pi recovery time courses using the single-pool model, and from Pi recovery time courses using a multi-pool model in which the Pi signal lineshape was segmented into four pH-specific pools: alkaline (pH 7.3 ± 0.2), neutral (pH 7.0 ± 0.1), mildly acidic (pH 6.8 ± 0.1), and moderately acidic (pH 6.6 ± 0.1). <b>Results:</b> The single-pool model showed that during exercise, Pi increased proportionally to PCr depletion, and both Pi and PCr recovered monoexponentially immediately after exercise with <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mo>τ</mo></mrow><mrow><mi>Pi</mi></mrow></msub><mo> </mo><mfenced separators="|"><mrow><mn>33</mn><mo>±</mo><mn>9</mn><mo> </mo><mi mathvariant="normal">s</mi></mrow></mfenced><mo><</mo><msub><mrow><mo>τ</mo></mrow><mrow><mi>PCr</mi></mrow></msub><mo> </mo><mo>(</mo><mn>40</mn><mo> </mo><mo>±</mo><mn>9</mn><mo> </mo><mi mathvariant="normal">s</mi><mo>)</mo></mrow></semantics></math></inline-formula>; ATP remained stable while pH exhibited a “heart-beat” pattern, characterized by an initial alkalization followed by neutralization during exercise, a post-exercise acidic undershoot, and a subsequent slow recovery (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mo>τ</mo></mrow><mrow><mi>pH</mi></mrow></msub><mo>≫</mo><msub><mrow><mo>τ</mo></mrow><mrow><mi>PCr</mi></mrow></msub></mrow></semantics></math></inline-formula>). The four-pool model demonstrated a pronounced pH dependence of Pi recovery, with slower recovery at lower pH (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mo>τ</mo></mrow><mrow><mi>Pi</mi></mrow></msub></mrow></semantics></math></inline-formula>: 19 ± 6 s at pH 7.3, 25 ± 7 s at pH 7.0, 32 ± 11 s at pH 6.8, and 46 ± 17 s at pH 6.6). Pi recovery is slowed with aging under acidic conditions, with little or no effect observed at neutral or alkaline pH. These results provide new insights into skeletal muscle metabolic heterogeneity, reflecting how different myofiber microenvironments modulate ATP synthesis. <b>Conclusions:</b> By overcoming the constraints of the single-pool model, the proposed multi-pool framework uncovers pH-dependent ATP synthesis and provides direct evidence of pronounced metabolic heterogeneity in skeletal muscle during exercise and recovery.

Sérgio Basílio, Marconi Ribeiro Furtado Júnior, Cleyton Batista de Alvarenga et al.

Droplet size is a key factor in minimizing spray drift. Different types of adjuvants and sprayer operating pressures can affect the droplet size distribution in various ways. This study aimed to evaluate the effects of commercial adjuvants, namely, acids and surfactant (AS), silicone surfactant (SS), organosilicone surfactant (OS), mineral oil (MO and MO₂), and copolymer (CP) adjuvants, on the droplet spectra and physicochemical properties of aqueous solutions. Hydrogen potential (pH), volumetric mass (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>V</mi><mi>M</mi></mrow></semantics></math></inline-formula>), electrical conductivity (EC), surface tension (ST), contact angle (CA), and droplet spectra were measured. The droplet spectrum variables, including volumetric diameters (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>D</mi><mrow><mi>v</mi><mn>0.1</mn></mrow></msub></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>D</mi><mrow><mi>v</mi><mn>0.5</mn></mrow></msub></mrow></semantics></math></inline-formula>, and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>D</mi><mrow><mi>v</mi><mn>0.9</mn></mrow></msub></mrow></semantics></math></inline-formula>), the Relative Span Factor (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>R</mi><mi>S</mi><mi>F</mi></mrow></semantics></math></inline-formula>), and percentages of the total volume of droplets with a diameter smaller than 100 µm (V100) and larger than 500 µm (V500), were determined using a laser diffraction particle analyzer (Malvern Spraytec). Spraying tests were carried out using the AXI 11003 flat fan nozzle at pressures of (0.1, 0.2, 0.3, 0.4, and 0.5) MPa. The increase in pressure increased the V100 and the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>R</mi><mi>S</mi><mi>F</mi></mrow></semantics></math></inline-formula>, with greater sensitivity observed for SS. Adjuvants such as AS, MO₂ and OS showed a more balanced trend, with a smaller increase in fine droplets and a greater reduction in coarse droplets. The principal component analysis (PCA) revealed that the droplet spectrum variables were the ones that best explained the variation among the solutions. A negative correlation was identified between EC and other physicochemical properties, such as pH, ST, and CA. Therefore, these properties alone did not determine the atomization pattern. The study demonstrates that optimizing spray quality and minimizing drift require a combined consideration of adjuvant physicochemical properties and their interaction with operational pressure.

Kai Zhao, Haiqing Tian, Jue Zhang et al.

Non-destructive detection of maize silage quality is essential. The aim is to propose a fast and non-destructive silage pH detection method based on a colorimetric sensor array (CSA). Extended color components, a novel sensitive dye screening method, and a feature screening method were integrated and applied to enhance pH detection. Fifty color components were constructed from five color spaces and used to extract information about the response of CSA to silage. Forward and backward stepwise selection and support vector regression (SVR) were combined to create a sensitive dye screening method, which was used to determine the optimal sensitive dye. The variable combination population analysis–iteratively retains informative variables algorithm was iterated to optimize effective features. Consequently, six hundred variables were extracted from the twelve dyes, which were able to comprehensively and finely characterize the CSA response. Four sensitive dyes were screened out from the twelve dyes, which were sensitive to silage volatile compounds and accurately reflected the odor changes. Twenty-eight effective features were preferred, based on which the SVR model had <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>, <i>RMSEP</i> and <i>RPD</i> scores of 0.9533, 0.4186, and 4.4186, respectively; the pH prediction performance was substantially improved. This study provides technical support for the scientific evaluation of silage quality.

Seyyed Hossein Monsefi Estakhrposhti, Jingjing Xu, Margit Gföhler et al.

Chronic respiratory diseases claim nearly four million lives annually, making them the third leading cause of death worldwide. Extracorporeal membrane oxygenation (ECMO) is often the last line of support for patients with severe lung failure. Still, its performance is limited by an incomplete understanding of gas exchange in hollow fiber membrane (HFM) oxygenators. Computational fluid dynamics (CFD) has become a robust oxygenator design and optimization tool. However, most models oversimplify O₂ and CO₂ transport by ignoring their physiological coupling, instead relying on fixed saturation curves or constant-content assumptions. For the first time, this study introduces a novel physiologically informed CFD model that integrates the Bohr and Haldane effects to capture the coupled transport of oxygen and carbon dioxide as functions of local pH, temperature, and gas partial pressures. The model is validated against in vitro experimental data from the literature and assessed against established CFD models. The proposed CFD model achieved excellent agreement with experiments across blood flow rates (100–500 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mi>mL</mi><mo>/</mo><mi>min</mi></mrow></mrow></semantics></math></inline-formula> ), with relative errors below 5% for oxygen and 10–15% for carbon dioxide transfer. These results surpassed the accuracy of all existing CFD approaches, demonstrating that a carefully formulated single-phase model combined with physiologically informed diffusivities can outperform more complex multiphase simulations. This work provides a computationally efficient and physiologically realistic framework for oxygenator optimization, potentially accelerating device development, reducing reliance on costly in vitro testing, and enabling patient-specific simulations.

M. O. Sunday, M. O. Sunday, L. M. Dahler Heinlein et al.

<p>The high levels of sulfate in wintertime particles in Fairbanks, Alaska, are a subject of keen research interest and regulatory concern. Recent results from the 2022 Alaska Layered Pollution And Chemical Analysis (ALPACA) field campaign indicate that roughly 40 % of wintertime sulfate in Fairbanks is secondary, with hydrogen peroxide (HOOH) the dominant oxidant. Since formation of <span class="inline-formula">HOOH</span> in the gas phase should be negligible during ALPACA because of high levels of <span class="inline-formula">NO_<i>x</i></span>, we examined whether reactions within particles could be a significant source of <span class="inline-formula">HOOH</span>. To test this, we collected particulate matter (PM) samples during the ALPACA campaign, extracted them, illuminated them with simulated sunlight, and measured <span class="inline-formula">HOOH</span> production. Aqueous extracts showed significant light absorption, a result of brown carbon (BrC) from sources such as residential wood combustion. Photoformation rates of <span class="inline-formula">HOOH</span> in the PM extracts (PMEs; normalized to Fairbanks winter sunlight) range from 6 to 71 <span class="inline-formula">µM h⁻¹</span>. While light absorption is nearly independent of pH, <span class="inline-formula">HOOH</span> formation rates decrease with increasing pH. Extrapolating to the concentrated conditions of aerosol liquid water (ALW) gives an average rate of in-particle <span class="inline-formula">HOOH</span> formation of <span class="inline-formula">∼</span> 0.1 <span class="inline-formula">M h⁻¹</span>. Corresponding rates of sulfate formation from particle-produced <span class="inline-formula">HOOH</span> are 0.05–0.5 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">µ</mi><mi mathvariant="normal">g</mi><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">m</mi><mrow><mo>-</mo><mn mathvariant="normal">3</mn></mrow></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">h</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="53pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="bbefb9113aea0e66c18f7309e2e62feb"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-25-5087-2025-ie00001.svg" width="53pt" height="15pt" src="acp-25-5087-2025-ie00001.png"/></svg:svg></span></span>, accounting for a significant portion of the secondary sulfate production rate. Our results show that <span class="inline-formula">HOOH</span> formed in particles makes an important contribution to sulfate formation in ambient wintertime particles, even under the low actinic flux conditions typical of winter in subarctic locations like Fairbanks.</p>

Yongliang Xiong, Yifeng Wang

Development of a defensible source-term model (STM), usually a thermodynamical model for radionuclide solubility calculations, is critical to a performance assessment (PA) of a geologic repository for nuclear waste disposal. Such a model is generally subjected to rigorous regulatory scrutiny. In this article, we highlight key guiding principles for STM model development and validation in nuclear waste management. We illustrate these principles by closely examining three recently developed thermodynamic models with the Pitzer formulism for aqueous H⁺—Nd³⁺—NO₃⁻(—oxalate) systems in a reverse alphabetical order of the authors: the XW model developed by Xiong and Wang, the OWC model developed by Oakes et al., and the GLC model developed by Guignot et al., among which the XW model deals with trace activity coefficients for Nd(III), while the OWC and GLC models are for concentrated Nd(NO₃)₃ electrolyte solutions. The principles highlighted include the following: (1) <b>Principle 1. Validation against independent experimental data</b>: A model should be validated against experimental data or field observations that have not been used in the original model parameterization. We tested the XW model against multiple independent experimental data sets including electromotive force (EMF), solubility, water vapor, and water activity measurements. The results show that the XW model is accurate and valid for its intended use for predicting trace activity coefficients and therefore Nd solubility in repository environments. (2) <b>Principle 2</b>. <b>Testing for relevant and sensitive variables</b>: Solution pH is such a variable for an STM and easily acquirable. All three models are checked for their ability to predict pH conditions in Nd(NO₃)₃ electrolyte solutions. The OWC model fails to provide a reasonable estimate for solution pH conditions, thus casting serious doubt on its validity for a source-term calculation. In contrast, both the XW and GLC models predict close-to-neutral pH values, in agreement with experimental measurements. (3) <b>Principle 3</b>. <b>Honoring physical constraints</b>: Upon close examination, it is found that the Nd(III)-NO₃ association schema in the OWC model suffers from two shortcomings. Firstly, its second stepwise stability constant for Nd(NO₃)₂⁺ (log <i>K</i>₂) is much higher than the first stepwise stability constant for NdNO₃²⁺ (log <i>K</i>₁), thus violating the general rule of (log <i>K</i>₂–log <i>K</i>₁) < 0, or <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mfrac><msub><mi>K</mi><mn>1</mn></msub><msub><mi>K</mi><mn>2</mn></msub></mfrac><mo>></mo><mn>1</mn></mrow></semantics></math></inline-formula>. Secondly, the OWC model predicts abnormally high activity coefficients for Nd(NO₃)₂⁺ (up to ~900) as the concentration increases. (4) <b>Principle 4</b>. <b>Minimizing degrees of freedom for model fitting</b>: The OWC model with nine fitted parameters is compared with the GLC model with five fitted parameters, as both models apply to the concentrated region for Nd(NO₃)₃ electrolyte solutions. The latter appears superior to the former because the latter can fit osmotic coefficient data equally well with fewer model parameters. The work presented here thus illustrates the salient points of geochemical model development, selection, and validation in nuclear waste management.

Zhichen Liu, Yingxin Huang, Qibiao Li et al.

High pH, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mi>Na</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow></semantics></math></inline-formula>, and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>(</mo><msubsup><mrow><mi>CO</mi></mrow><mrow><mn>3</mn></mrow><mrow><mn>2</mn><mo>−</mo></mrow></msubsup><mo>+</mo><msubsup><mrow><mi>HCO</mi></mrow><mrow><mn>3</mn></mrow><mrow><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula>) are the primary characteristics of soda saline–alkali soil. Current strategies for ameliorating soda saline–alkali soil often involve the combined use of cow manure and maize straw, the addition of biochar (BC), and the inoculation of <i>Bacillus subtilis</i> (BS). In this study, <i>B. subtilis</i>-loaded biochar (BSC) was prepared using an adsorption technique. An incubation experiment was conducted. The treatments were as follows: soda saline–alkali soil amended with maize straw and cow manure (T₁), which was used as a control; T₁ supplemented with earthworms (T₂); and T₂ supplemented with BS (T₃), BC (T₄), or BSC (T₅). After a 60-day incubation, T₅ showed the most significant reduction in pH, ESP, and (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mrow><mi mathvariant="normal">H</mi><mi mathvariant="normal">C</mi><mi mathvariant="normal">O</mi></mrow><mrow><mn>3</mn></mrow><mrow><mo>−</mo></mrow></msubsup><mo> </mo></mrow></semantics></math></inline-formula> + <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo> </mo><msubsup><mrow><mi mathvariant="normal">C</mi><mi mathvariant="normal">O</mi></mrow><mrow><mn>3</mn></mrow><mrow><mn>2</mn><mo>−</mo></mrow></msubsup></mrow></semantics></math></inline-formula>) concentrations, with reductions of 0.24 units, 3.26%, and 120 mg kg⁻¹, respectively, compared to the T₁ treatment. The content of soil humic acid, available potassium, and available nitrogen and the activities of β-glucosidase and urease were highest in T₅, increasing by 33.5%, 70.1%, 26.1%, 19.0%, and 17.9%, respectively. Microbial sequencing analysis revealed that the <i>Bacillus</i> abundance in T₃ was highest during the first 45 days (2.51–3.65%), while the <i>Bacillus</i> abundance in T₅ peaked at 3.22% after the 60-day incubation. The soil that was cultivated for 60 days in the experiments was then used for planting alfalfa. T₅ showed the highest alfalfa aboveground biomass and peroxidase, increasing by 30.1% and 73.1%, respectively, compared with T₁. This study demonstrated that loading onto biochar is beneficial for the survival of <i>B. subtilis</i> in soda saline–alkali soil. When traditional organic materials are used, the combination of earthworms and <i>B</i>. <i>subtilis</i>-loaded biochar significantly alleviates the constraints of soda saline–alkali soil.

D. González-Santana, M. Segovia, M. González-Dávila et al.

<p>The addition of carbonate minerals to seawater through an artificial ocean alkalinity enhancement (OAE) process increases the concentrations of hydroxide, bicarbonate, and carbonate ions. This leads to changes in the pH and the buffering capacity of the seawater. Consequently, OAE could have relevant effects on marine organisms and in the speciation and concentration of trace metals that are essential for their physiology. During September and October 2021, a mesocosm experiment was carried out in the coastal waters of Gran Canaria (Spain), consisting on the controlled variation of total alkalinity (TA). Different concentrations of carbonate salts (NaHCO<span class="inline-formula">₃</span> and Na<span class="inline-formula">₂</span>CO<span class="inline-formula">₃</span>) previously homogenized were added to each mesocosm to achieve an alkalinity gradient between <span class="inline-formula">Δ</span>0 to <span class="inline-formula">Δ</span>2400 <span class="inline-formula">µ</span>mol L<span class="inline-formula">⁻¹</span>. The lowest point of the gradient was 2400 <span class="inline-formula">µ</span>mol kg<span class="inline-formula">⁻¹</span>, being the natural alkalinity of the medium, and the highest point was 4800 <span class="inline-formula">µ</span>mol kg<span class="inline-formula">⁻¹</span>. Iron (Fe) speciation was monitored during this experiment to analyse total dissolved iron (TdFe, unfiltered samples), dissolved iron (dFe, filtered through a 0.2 <span class="inline-formula">µ</span>m pore size filter), soluble iron (sFe, filtered through a 0.02 <span class="inline-formula">µ</span>m pore size filter), dissolved labile iron (dFe<span class="inline-formula">^′</span>), iron-binding ligands (LFe), and their conditional stability constants (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi>K</mi><mi mathvariant="normal">FeL</mi><mo>′</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="23pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="71dd64848558b1d613703afb4f6eca40"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-21-2705-2024-ie00001.svg" width="23pt" height="15pt" src="bg-21-2705-2024-ie00001.png"/></svg:svg></span></span>) because of change due to OAE and the experimental conditions in each mesocosm. Observed iron concentrations were within the expected range for coastal waters, with no significant increases due to OAE. However, there were variations in Fe size fractionation during the experiment. This could potentially be due to chemical changes caused by OAE, but such an effect is masked by the stronger biological interactions. In terms of size fractionation, sFe was below 1.0 nmol L<span class="inline-formula">⁻¹</span>, dFe concentrations were within 0.5–4.0 nmol L<span class="inline-formula">⁻¹</span>, and TdFe was within 1.5–7.5 nmol L<span class="inline-formula">⁻¹</span>. Our results show that over 99 % of Fe was complexed, mainly by <span class="inline-formula"><i>L</i>₁</span> and <span class="inline-formula"><i>L</i>₂</span> ligands with <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M21" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi>k</mi><mrow><msup><mi mathvariant="normal">Fe</mi><mo>′</mo></msup><mi mathvariant="normal">L</mi></mrow><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="85c04a9f29d686cdd800dea220bbda6e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-21-2705-2024-ie00002.svg" width="24pt" height="15pt" src="bg-21-2705-2024-ie00002.png"/></svg:svg></span></span> ranging between 10.92 <span class="inline-formula">±</span> 0.11 and 12.68 <span class="inline-formula">±</span> 0.32, with LFe ranging from 1.51 <span class="inline-formula">±</span> 0.18 to 12.3 <span class="inline-formula">±</span> 1.8 nmol L<span class="inline-formula">⁻¹</span>. Our data on iron size fractionation, concentration, and iron-binding ligands substantiate that the introduction of sodium salts in this mesocosm experiment did not modify iron dynamics. As a consequence, phytoplankton remained unaffected by alterations in this crucial element.</p>

Lénaïck Hervé, Svetlana Heyte, Maya Marinova et al.

In the quest to combat global warming, traditional thermal chemistry processes are giving way to selective photocatalysis, an eco-friendly approach that operates under milder conditions, using benign solvents like water. Benzaldehyde, a versatile compound with applications spanning agroindustry, pharmaceuticals, and cosmetics, serves as a fundamental building block for various fine chemicals. This study aims at enhancing benzaldehyde production sustainability by utilizing photooxidation of benzyl alcohol. Gold nanoparticle-based catalysts are renowned for their exceptional efficiency in oxidizing bio-based molecules. In this research, Au nanoparticles were anchored onto three distinct supports: <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">T</mi><mi mathvariant="normal">i</mi><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">Z</mi><mi mathvariant="normal">r</mi><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub></mrow></semantics></math></inline-formula>, and graphitic carbon nitride (g-<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi mathvariant="normal">C</mi><mn>3</mn></msub><msub><mi mathvariant="normal">N</mi><mn>4</mn></msub></mrow></semantics></math></inline-formula>). The objective was to investigate the influence of the support material on the selective photocatalysis of benzyl alcohol. In the preparation of g-<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi mathvariant="normal">C</mi><mn>3</mn></msub><msub><mi mathvariant="normal">N</mi><mn>4</mn></msub></mrow></semantics></math></inline-formula>, three different precursors—melamine, urea, and a 50:50 mixture of both—were chosen to analyze their impact on catalyst performance. After 4 h of irradiation at 365 nm, operating under acidic conditions (pH = 2), the Au photocatalyst on graphitic carbon nitride support synthesized using urea precursor (Au@g-<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi mathvariant="normal">C</mi><mn>3</mn></msub><msub><mi mathvariant="normal">N</mi><mrow><mn>4</mn><mo>(</mo><mi>u</mi><mi>r</mi><mi>e</mi><mi>a</mi><mo>)</mo></mrow></msub></mrow></semantics></math></inline-formula>) displayed the optimal balance between conversion (75%) and selectivity (85%). This formulation outperformed the benchmark Au@TiO₂, which achieved a similar conversion rate (80%) but exhibited lower selectivity (55%).

Laure Guy, Maëlle Mosser, Delphine Pitrat et al.

A series of molecules that possess two quinolines, benzoquinolines, or phenanthrolines connected in a chiral fashion by a biaryl junction along with their water-soluble derivatives was developed and characterized. The influence of the structure on the basicity of the nitrogen atoms in two heterocycles was examined and the photophysical and chiroptical switching activity of the compounds upon protonation was studied both experimentally and computationally. The results demonstrated that changes in the electronic structure of the protonated vs. neutral species, promoting a bathochromic shift of dominant electronic transitions and alternation of their character from <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>π</mi></semantics></math></inline-formula>-to-<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>π</mi></semantics></math></inline-formula>* to charge-transfer-type, when additionally accompanied by the high structural flexibility of a system, leading to changes in conformational preferences upon proton binding, produce particularly pronounced modifications of the spectral properties in acidic medium. The latter combined with reversibility of the read-out make some of the molecules in this series very promising multifunctional pH probes.

Aya I. Tagyan, Manal M. Yasser, Ahmed M. Mousa et al.

Fungi were used as one of the most common bioremediation methods. From this perspective, our study highlights the optimization of Alizarin Red S (ARS) dye adsorption performance for the sodium alginate (SA) by using the fungus <i>Aspergillus terreus</i> (<i>A. terreus</i>) to form a composite bead and the possibility of its reusability. This was accomplished by mixing SA with different ratios of biomass powder of <i>A. terreus,</i> including 0%, 10%, 20%, 30%, and 40%, to form composite beads of <i>A. terreus</i>/SA-0%, <i>A. terreus</i>/SA-10%, <i>A. terreus</i>/SA-20%, <i>A. terreus</i>/SA-30%, and <i>A. terreus</i>/SA-40%, respectively. The ARS adsorption characteristics of these composite mixtures were analyzed at various mass ratios, temperatures, pH values, and initial concentrations. Moreover, sophisticated techniques, such as scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR), were employed to detect the morphological and chemical properties of this composite, respectively. The experimental results revealed that <i>A. terreus</i>/SA-20% composite beads have the highest adsorption capacity of 188 mg/g. Its optimum adsorption conditions were achieved at 45 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>∘</mo></msup></semantics></math></inline-formula>C and pH 3. Moreover, the ARS adsorption was well explained by the Langmuir isotherm (q_m = 192.30 mg/g) and pseudo-second-order and intra-particle diffusion kinetics. The SEM and FTIR findings corroborated the superior uptake of A. terreus/SA-20% composite beads. Lastly, the <i>A. terreus</i>/SA-20% composite beads can be employed as an eco-friendly and sustainable alternative to other common adsorbents for ARS.

Sarizhat D. Tataeva, Kurban E. Magomedov, Ruslan Z. Zeynalov et al.

The technology for manufacturing a film membrane of the metamizole-selective electrode containing ion associate metamizole-octadecylammonium ODAH<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>+</mo></msup></semantics></math></inline-formula>MT<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>−</mo></msup></semantics></math></inline-formula> as an electrode active component (EAC) has been proposed. The main potentiometric characteristics of the metamizole-selective electrode have been determined. The expediency of the proposed design of the metamizole selective electrode for the determination of metamizole in dosage forms has been substantiated. The best composition of the membrane (wt.%) of the metamizole-selective electrode has corresponded to: ODAH<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>+</mo></msup></semantics></math></inline-formula>MT<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>−</mo></msup></semantics></math></inline-formula>—5.3; 2-nitrophenyloctylether—63.1; poly(vinyl chloride)—31.6. Electrode-active component in the membrane phase functions as an ion associate ODAH<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>+</mo></msup></semantics></math></inline-formula>MT<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>−</mo></msup></semantics></math></inline-formula>. Potentiometric characteristics of metamizole-selective electrode have been determined, which corresponded to: linear range 1 × 10<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></semantics></math></inline-formula>–1 × 10<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></semantics></math></inline-formula> with limit of detection 4.58 × 10<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup></semantics></math></inline-formula> M, electrode function slope −48.5 mV/dec., working interval pH 4.5–7.3, response time 60 s. The potentiometric coefficients of selectivity of the metamizole-selective electrode with respect to various ions have been determined. The possibility of determining metamizole in a medicinal product has been tested. The results of the analyses show good agreement between the two methods (relative error less than 7.0%) with coefficients of variation less than 5% for MT-SE and iodometric methods.

Róbert Kormány, Norbert Rácz, Szabolcs Fekete et al.

In-process control (IPC) is an important task during chemical syntheses in pharmaceutical industry. Despite the fact that each chemical reaction is unique, the most common analytical technique used for IPC analysis is high performance liquid chromatography (HPLC). Today, the so-called “Quality by Design” (QbD) principle is often being applied rather than “Trial and Error” approach for HPLC method development. The QbD approach requires only for a very few experimental measurements to find the appropriate stationary phase and optimal chromatographic conditions such as the composition of mobile phase, gradient steepness or time (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>t</mi><mi>G</mi></msub></semantics></math></inline-formula>), temperature (<i>T</i>), and mobile phase pH. In this study, the applicability of a multifactorial liquid chromatographic optimization software was studied in an extended knowledge space. Using state-of-the-art ultra-high performance liquid chromatography (UHPLC), the analysis time can significantly be shortened. By using UHPLC, it is possible to analyse the composition of the reaction mixture within few minutes. In this work, a mixture of route of synthesis of apixaban was analysed on short narrow bore column (50 × 2.1 mm, packed with sub-2 µm particles) resulting in short analysis time. The aim of the study was to cover a relatively narrow range of method parameters (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>t</mi><mi>G</mi></msub></semantics></math></inline-formula>, <i>T</i>, pH) in order to find a robust working point (zone). The results of the virtual (modeled) robustness testing were systematically compared to experimental measurements and Design of Experiments (DoE) based predictions.

Youngdeuk Lee, Eunyoung Jo, Yeon-Ju Lee et al.

We recently identified a <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">β</mi></semantics></math></inline-formula>-agarase, Gaa16B, in the marine bacterium <i>Gilvimarinus agarilyticus</i> JEA5. Gaa16B, belonging to the glycoside hydrolase 16 family of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">β</mi></semantics></math></inline-formula>-agarases, shows less than 70.9% amino acid similarity with previously characterized agarases. Recombinant Gaa16B lacking the carbohydrate-binding region (rGaa16Bc) was overexpressed in <i>Escherichia coli</i> and purified. Activity assays revealed the optimal temperature and pH of rGaa16Bc to be 55 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>∘</mo></msup></semantics></math></inline-formula>C and pH 6–7, respectively, and the protein was highly stable at 55 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>∘</mo></msup></semantics></math></inline-formula>C for 90 min. Additionally, rGaa16Bc activity was strongly enhanced (2.3-fold) in the presence of 2.5 mM MnCl₂. The <i>K_m</i> and <i>V_max</i> of rGaa16Bc for agarose were 6.4 mg/mL and 953 U/mg, respectively. Thin-layer chromatography analysis revealed that rGaa16Bc can hydrolyze agarose into neoagarotetraose and neoagarobiose. Partial hydrolysis products (PHPs) of rGaa16Bc had an average molecular weight of 88–102 kDa and exhibited > 60% hyaluronidase inhibition activity at a concentration of 1 mg/mL, whereas the completely hydrolyzed product (CHP) showed no hyaluronidase at the same concentration. The biochemical properties of Gaa16B suggest that it could be useful for producing functional neoagaro-oligosaccharides. Additionally, the PHP of rGaa16Bc may be useful in promoting its utilization, which is limited due to the gel strength of agar.

Evgenia Voulgari, François Krummenacher, Maher Kayal

This article describes the design and the characterization of the ANTIGONE (ANalog To dIGital cONvErter) ASIC (Application Specific Integrated Circuit) built in AMS 0.35 m technology for low dc-current sensing. This energy-efficient ASIC was specifically designed to interface with multiple Ion-Sensitive Field-Effect Transistors (ISFETs) and detect biomarkers like pH, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow><mi>Na</mi></mrow><mo>+</mo></msup></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow><mi mathvariant="normal">K</mi></mrow><mo>+</mo></msup></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow><mi>Ca</mi></mrow><mrow><mn>2</mn><mo>+</mo></mrow></msup></semantics></math></inline-formula> in human sweat. The ISFET-ASIC system can allow real-time noninvasive and continuous health monitoring. The ANTIGONE ASIC architecture is based on the current-to-frequency converter through the charge balancing principle. The same front-end can digitize multiple currents produced by four sweat ISFET sensors in time multiplexing. The front-end demonstrates good linearity over a dynamic range that spans from 1 pA up to 500 nA. The consumed energy per conversion is less than 1 J. The chip is programmable and works in eight different modes of operation. The system uses a standard Serial Peripheral Interface (SPI) to configure, control and read the digitally converted sensor data. The chip is controlled by a portable device over Bluetooth Low Energy (BLE) through a Microcontroller Unit (MCU). The sweat sensing system is part of a bigger wearable platform that exploits the convergence of multiparameter biosensors and environmental sensors for personalized and preventive healthcare.

Ma del Refugio Cuevas-Flores, Massimiliano Bartolomei, Marco Antonio García-Revilla et al.

The physical adsorption of cisplatin (CP) on graphene oxide (GO) and reduced graphene oxide (rGO) is investigated at the DFT level of theory by exploiting suitable molecular prototypes representing the most probable adsorbing regions of GO and rGO nano-structures. The results show that the CP binding energy is enhanced with respect to that for the interaction with pristine graphene. This is due to the preferential adsorption of the drug in correspondence of the epoxy and hydroxy groups located on GO basal plane: an energy decomposition analysis of the corresponding binding energy reveals that the most attractive contribution comes from the electrostatic attraction between the -NH<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>3</mn> </msub> </semantics> </math> </inline-formula> ends of CP and the oxygen groups on (r)GO, which can be associated with hydrogen bonding effects. Moreover, it is found that the reactivity of the physically adsorbed CP is practically unaltered being the free energy variation of the first hydrolysis reaction almost matching that of its free (unadsorbed drug) counterpart. The reported results suggest that the CP physical adsorption on GO and rGO carriers is overall feasible being an exergonic process in aqueous solution. The CP adsorption could facilitate its solubility and transport in water solutions, exploiting the high hydrophilicity of the peripheral carboxylic groups located on the edge of the GO and rGO nano-structures. Moreover, the the higher affinity of CP with respect to the oxidized sites suggests a possible dependence of drug loading and release on pH conditions, which would highly facilitate its specific delivery.

Y. Tian, Y. Tian, Y. Tian et al.

<p>Nitric oxide (NO) is a short-lived intermediate of the oceanic nitrogen cycle. However, our knowledge about its production and consumption pathways in oceanic environments is rudimentary. In order to decipher the major factors affecting NO photochemical production, we irradiated several artificial seawater samples as well as 31 natural surface seawater samples in laboratory experiments. The seawater samples were collected during a cruise to the western tropical North Pacific Ocean (WTNP, a N–S section from 36 to 2<span class="inline-formula">^∘</span>&thinsp;N along 146 to 143<span class="inline-formula">^∘</span>&thinsp;E with 6 and 12 stations, respectively, and a W–E section from 137 to 161<span class="inline-formula">^∘</span>&thinsp;E along the Equator with 13 stations) from November 2015 to January 2016. NO photoproduction rates from dissolved nitrite in artificial seawater showed increasing trends with decreasing pH, increasing temperature, and increasing salinity. In contrast, NO photoproduction rates (average: <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">0.5</mn><mo>±</mo><mn mathvariant="normal">0.2</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">12</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="82pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="8b0024d5cf7d62b1f85acc37b9872754"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="os-16-135-2020-ie00001.svg" width="82pt" height="14pt" src="os-16-135-2020-ie00001.png"/></svg:svg></span></span>&thinsp;mol&thinsp;L<span class="inline-formula">⁻¹</span>&thinsp;s<span class="inline-formula">⁻¹</span>) in the natural seawater samples from the WTNP did not show any correlations with pH, water temperature, salinity, or dissolved inorganic nitrite concentrations. The flux induced by NO photoproduction in the WTNP (average: <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">13</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">12</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="9ae0e0bfa9d6268e2fb2bd27ff4f362b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="os-16-135-2020-ie00002.svg" width="52pt" height="14pt" src="os-16-135-2020-ie00002.png"/></svg:svg></span></span>&thinsp;mol&thinsp;m<span class="inline-formula">⁻²</span>&thinsp;s<span class="inline-formula">⁻¹</span>) was significantly larger than the NO air–sea flux density (average: <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">1.8</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">12</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="55pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="938b59228ab2d319d2f6d76a068cb05e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="os-16-135-2020-ie00003.svg" width="55pt" height="14pt" src="os-16-135-2020-ie00003.png"/></svg:svg></span></span>&thinsp;mol&thinsp;m<span class="inline-formula">⁻²</span>&thinsp;s<span class="inline-formula">⁻¹</span>), indicating a further NO loss process in the surface layer.</p>

G. Ayyappan, R. Gowthami

Guangzhao Wang, Feng Zhou, Binfang Yuan et al.

By means of a hybrid density functional, we comprehensively investigate the energetic, electronic, optical properties, and band edge alignments of two-dimensional (2D) CdS/g-C<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>3</mn> </msub> </semantics> </math> </inline-formula>N<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>4</mn> </msub> </semantics> </math> </inline-formula> heterostructures by considering the effect of biaxial strain and pH value, so as to improve the photocatalytic activity. The results reveal that a CdS monolayer weakly contacts with g-C<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>3</mn> </msub> </semantics> </math> </inline-formula>N<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>4</mn> </msub> </semantics> </math> </inline-formula>, forming a type II van der Waals (vdW) heterostructure. The narrow bandgap makes CdS/g-C<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>3</mn> </msub> </semantics> </math> </inline-formula>N<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>4</mn> </msub> </semantics> </math> </inline-formula> suitable for absorbing visible light and the induced built-in electric field between the interface promotes the effective separation of photogenerated carriers. Through applying the biaxial strain, the interface adhesion energy, bandgap, and band edge positions, in contrast with water, redox levels of CdS/g-C<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>3</mn> </msub> </semantics> </math> </inline-formula>N<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>4</mn> </msub> </semantics> </math> </inline-formula> can be obviously adjusted. Especially, the pH of electrolyte also significantly influences the photocatalytic performance of CdS/g-C<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>3</mn> </msub> </semantics> </math> </inline-formula>N<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>4</mn> </msub> </semantics> </math> </inline-formula>. When pH is smaller than 6.5, the band edge alignments of CdS/g-C<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>3</mn> </msub> </semantics> </math> </inline-formula>N<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>4</mn> </msub> </semantics> </math> </inline-formula> are thermodynamically beneficial for oxygen and hydrogen generation. Our findings offer a theoretical basis to develop g-C<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>3</mn> </msub> </semantics> </math> </inline-formula>N<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>4</mn> </msub> </semantics> </math> </inline-formula>-based water-splitting photocatalysts.

Michael K. -H. Kiessling, Matthias Lienert, A. Shadi Tahvildar-Zadeh

A Lorenz-covariant system of wave equations is formulated for a quantum-mechanical two-body system in one space dimension, comprised of one electron and one photon. Manifest Lorentz covariance is achieved using Dirac's formalism of multi-time wave functions, i.e., wave functions $Ψ(\mathbf{x}_{ph},\mathbf{x}_{el})$ where $\mathbf{x}_{el},\mathbf{x}_{ph}$ are the generic spacetime events of the electron and photon, respectively. Their interaction is implemented via a Lorentz-invariant no-crossing-of-paths boundary condition at the coincidence submanifold $\{\mathbf{x}_{el}=\mathbf{x}_{ph}\}$, compatible with particle current conservation. The corresponding initial-boundary-value problem is proved to be well-posed. Electron and photon trajectories are shown to exist globally in a Hypersurface Bohm--Dirac theory, for typical particle initial conditions. Also presented are the results of some numerical experiments which illustrate Compton scattering as well as a new phenomenon: photon capture and release by the electron.