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A class of parametric optimal control problems governed by semilinear parabolic equations with mixed pointwise constraints is investigated. The perturbations appear in the objective functional, the state equation and in mixed pointwise constraints. By analyzing regularity and establishing stability condition of Lagrange multipliers we prove that, if the unperturbed problem satisfies the strong second-order sufficient condition, then the solution map and the associated Lagrange multipliers are locally Lipschitz continuous functions of parameters. [ABSTRACT FROM AUTHOR]

In this work, a known Eddy Current (EC) model is adapted to characterize subsurface defects in carbon fiber-reinforced polymer (CFRP) plates intended for the civil aerospace industry. The considered defects include delaminations, microcracks, porosity, fiber breakage, and the simultaneous presence of these defects. Each defect is modeled as an additive variation in the material's electrical conductivity tensor, allowing for a detailed mathematical representation of the defect's influence on the CFRP's electromagnetic behavior. The additivity of the variations in the conductivity tensor is justified by the assumption that the defects are not visible to the naked eye, implying that the material does not require non-destructive testing. The adapted EC model admits a unique and stable solution by verifying that all analytical steps are satisfied. To reconstruct 2D maps of the magnetic flux density amplitude, a FEM formulation is adopted, based on the energy functional because it ensures a stable and consistent numerical formulation given its coercivity. Moreover, the numerical approach allows precise and reliable numerical solutions, enhancing the capability to detect and quantify defects. The numerical results show that the obtained 2D maps are entirely superimposable on those highlighting the distribution of mechanical stress states known in the literature, offering a clear advantage in terms of detection costs. This approach provides an effective and economical solution for the non-destructive inspection of CFRP, ensuring accurate and timely defect diagnosis for maintaining structural integrity. [ABSTRACT FROM AUTHOR]

In the context of the demand for mass customization of products, a trade-off between highly efficient automated systems and flexible manual operators is sought. The linear arrangement of workstations made it possible to divide the process into many simple operations, which increases production efficiency, but also results in an increase in the number of workstations and a significant extension of the line. A human operator is usually treated as a quasi-mechanical object, and a human error is considered, similarly, as a failure of a technical component. However, human behavior is more complex and difficult to predict. A mathematical model of a new production organization is presented, including dividing the traditional production line into shorter sections or replacing the serial assembly line with a U-line with cells. Moreover, the reliability of operator and technical means are distinguished. Work-in-progress inventories are located between line sections to improve system stability. The stability of the assembly line is examined based on the system configuration and probabilistic estimates of human failure. The influence of the symmetry of reliability parameters of people on key performance indicators (KPI (headcount), KPI (surface) and KPI (Overall Equipment Effectiveness) is examined. KPI (solution robustness) and KPI (quality robustness) are also presented in order to evaluate the impact of a disruption on the assembly line performance. New rules for assigning tasks to stations are proposed, taking into account the risk of disruptions in the execution of tasks. For comparison of assembly problems, heuristic methods with newly developed criteria are used. The results show the impact of symmetry/asymmetry on assembly line performance and an asymmetric distribution of manual assembly times that is significantly skewed to the right due to human errors. On the assembly line, the effects of these errors are cumulative and lead to longer assembly times and lower KPIs. [ABSTRACT FROM AUTHOR]

In [Phys. Rev. D 107, 104008 (2023)], we reported a novel exact closed-form solution which describes asymptotically flat spacetimes in pure ℛ 2 gravity. The solution is Ricci scalar flat, viz. ℛ ≡ 0 everywhere. Whereas any metric with a null Ricci scalar would trivially satisfy the ℛ 2 vacuo field equation, ℛ (ℛ μ ν − 1 4 g μ ν ℛ) + g μ ν □ ℛ − ∇ μ ∇ ν ℛ = 0 , in this paper, we shall show that our solution satisfies a "stronger" version of the ℛ 2 vacuo field equation, viz. ℛ μ ν − 1 4 g μ ν ℛ + ℛ − 1 (g μ ν □ ℛ − ∇ μ ∇ ν ℛ) = 0 , despite the term ℛ − 1 being singular. Even though ℛ identically vanishes, for our solution, the combinations ℛ − 1 ∇ μ ∇ ν ℛ and ℛ − 1 □ ℛ are free of singularity. This exceptional property sets our solution apart from the set of null-Ricci-scalar metrics and makes it a genuinely nontrivial solution. We further demonstrate that, as a member of a larger class of asymptotically de Sitter metrics, our solution is resilient against perturbations in the scalar curvature at largest distances, making it relevant for physical situations where the background deviates from asymptotic flatness. [ABSTRACT FROM AUTHOR]

In this work, a known Eddy Current (EC) model is adapted to characterize subsurface defects in carbon fiber-reinforced polymer (CFRP) plates intended for the civil aerospace industry. The considered defects include delaminations, microcracks, porosity, fiber breakage, and the simultaneous presence of these defects. Each defect is modeled as an additive variation in the material’s electrical conductivity tensor, allowing for a detailed mathematical representation of the defect’s influence on the CFRP’s electromagnetic behavior. The additivity of the variations in the conductivity tensor is justified by the assumption that the defects are not visible to the naked eye, implying that the material does not require non-destructive testing. The adapted EC model admits a unique and stable solution by verifying that all analytical steps are satisfied. To reconstruct 2D maps of the magnetic flux density amplitude, a FEM formulation is adopted, based on the energy functional because it ensures a stable and consistent numerical formulation given its coercivity. Moreover, the numerical approach allows precise and reliable numerical solutions, enhancing the capability to detect and quantify defects. The numerical results show that the obtained 2D maps are entirely superimposable on those highlighting the distribution of mechanical stress states known in the literature, offering a clear advantage in terms of detection costs. This approach provides an effective and economical solution for the non-destructive inspection of CFRP, ensuring accurate and timely defect diagnosis for maintaining structural integrity.

In this paper, we consider finite- and infinite-dimensional optimization problems with constraints of general type. We obtain sufficient conditions for stability of a strict solution and conditions for stability of a set of solutions with more than one point in it according to small perturbations of the problem parameters. For finite-dimensional extremal problems with equality-type constraints, we obtain stability conditions based on the construction of λ-truncations of mappings. [ABSTRACT FROM AUTHOR]

The purpose of this work is to build the analytical model of the behavior of a harmonic wave in a nonlinear optical medium with periodically arranged nanofilms. Methods. The modernized method is presented of non-smooth transformation of the argument to eliminate the Dirac functions on the right side of the non-linear inhomogeneous differential equation describing linear polarized wave behavior within a non-linear optical medium with periodically arranged conducting nanofilms. Small parameter methods, in particular, the averaging method, is also used to find an approximate analytical solution. Results. The fully analytical model of the behavior of a linear polarized harmonic wave within a nonlinear optical medium with periodically arranged conducting nanofilms is constructed. Conclusion. For the case of propagation of a linearly polarized harmonic wave in a nonlinear optical medium with periodically arranged conducting nanofilms, the mathematical model based on the non-smooth argument transformation method is constructed. The model is fully analytical, all expressions are obtained directly from Maxwell’s equations by identical transformations. The limits of its applicability are determined by the limits of application of the wave theory of light.

In the context of the demand for mass customization of products, a trade-off between highly efficient automated systems and flexible manual operators is sought. The linear arrangement of workstations made it possible to divide the process into many simple operations, which increases production efficiency, but also results in an increase in the number of workstations and a significant extension of the line. A human operator is usually treated as a quasi-mechanical object, and a human error is considered, similarly, as a failure of a technical component. However, human behavior is more complex and difficult to predict. A mathematical model of a new production organization is presented, including dividing the traditional production line into shorter sections or replacing the serial assembly line with a U-line with cells. Moreover, the reliability of operator and technical means are distinguished. Work-in-progress inventories are located between line sections to improve system stability. The stability of the assembly line is examined based on the system configuration and probabilistic estimates of human failure. The influence of the symmetry of reliability parameters of people on key performance indicators (KPI (headcount), KPI (surface) and KPI (Overall Equipment Effectiveness) is examined. KPI (solution robustness) and KPI (quality robustness) are also presented in order to evaluate the impact of a disruption on the assembly line performance. New rules for assigning tasks to stations are proposed, taking into account the risk of disruptions in the execution of tasks. For comparison of assembly problems, heuristic methods with newly developed criteria are used. The results show the impact of symmetry/asymmetry on assembly line performance and an asymmetric distribution of manual assembly times that is significantly skewed to the right due to human errors. On the assembly line, the effects of these errors are cumulative and lead to longer assembly times and lower KPIs.

Rapid, simple, and novel isocratic reverse-phase high-performance liquid chromatography (RP-HPLC) method was developed with stability, indicating potential for simultaneous estimation of chlorthalidone and amlodipine besylate in bulk and in tablet dosage form. The chromatographic elution was performed on Merck's Oyster ODS3 (5 μm, 150 mm × 4.6 mm i.d.) column with 20 mM phosphate buffer pH 2.5: methanol: acetonitrile (40:30:30, v/v/v) at flow rate 1.0 mL/min pumped through a column maintained at ambient temperature (about 25°C) with a response observed at 238 nm over an 8 min run time. The chlorthalidone and amlodipine were eluted at 2.219 min and 4.120 min, respectively. The method was linear: 74.9767 – 174.9455 μg/mL (R2 = 0.999) for chlorthalidone and 30.2266 – 70.5288 μg/mL (R2 = 0.999) for amlodipine. The percentage recovery average at three different levels was found to be 99.53, 99.47 and 98.32% for chlorthalidone and 101.23, 98.75 and 99.10% for amlodipine. The % RSD value was below 2.0 during the precision study. The mobile phase was stable for 2 days; preparations of standard and sample were stable at room temperature and refrigerated (2 – 8°C) for day 1. Additionally, the method is stability indicating, as it was able to distinguish the degraded product generated during forced degradation from active analytes. The method was validated according to the International Conference on Harmonization (ICH) guideline Q2 (R1) and can be used successfully for stability study and routine analysis. [ABSTRACT FROM AUTHOR]

This article provides UV-spectrophotometry data of technical lignin samples in solutions, which were acquired after ambient aging for up to 110 days or looped measurements on fresh solutions. UV-spectrophotometry of lignin is a useful technique, as it can a) quantify the concentration and purity of lignin in a given sample, b) determine the abundance of phenolic hydroxyl groups, and c) yield qualitative information about chemical modification of the lignin macromolecule. In addition, the technique is rapid and easy to use. Still, solutions of lignin are known to be unstable; in particular at high pH or in presence of UV-light. The data in this article may hence serve as guide in the experimental conduct and design, as it shows the reproducibility of UV-spectrophotometry measurements of lignin. Stock solutions of technical lignin were made according to previously published procedure [1]. The solutions in dimethyl sulfoxide (DMSO) were aged in 100 mL volumetric flasks with glass stopper, taking periodic samples for measurements in a Shimadzu UV-1900 UV−vis spectrophotometer. The instrument recorded the spectrum from 500 to 200 nm at 1.0 nm intervals and medium speed, using quartz cuvettes with a pathlength of 1 cm. In addition, looped measurements were conducted on fresh solutions, where the instrument repeated the spectral range of 500 to 200 nm for in total sixteen times. The latter examined solutions of technical lignin in DMSO solvent as well as in 0.2 N NaOH in water.

The local stability of the solution map to a parametric boundary control problem governed by semilinear elliptic equations with finite mixed pointwise constraints is considered in this paper. We prove that the solution map is locally Hölder continuous in L ∞ -norm of control variable when the strictly nonnegative second-order optimality conditions are satisfied for the unperturbed problem. [ABSTRACT FROM AUTHOR]

The theoretical and empirical performance of Empirical Risk Minimization (ERM) often suffers when loss functions are poorly behaved with large Lipschitz moduli and spurious sharp minimizers. We propose and analyze a counterpart to ERM called Diametrical Risk Minimization (DRM), which accounts for worst-case empirical risks within neighborhoods in parameter space. DRM has generalization bounds that are independent of Lipschitz moduli for convex as well as nonconvex problems and it can be implemented using a practical algorithm based on stochastic gradient descent. Numerical results illustrate the ability of DRM to find quality solutions with low generalization error in sharp empirical risk landscapes from benchmark neural network classification problems with corrupted labels. [ABSTRACT FROM AUTHOR]

This paper is concerned with the stability of minimizers to a parametric optimal control problem governed by semilinear elliptic equations with mixed pointwise control-state constraints. Under the strictly nonnegative second-order optimality condition assumption, we show that the solution map is locally Lipschitz continuous in L 2 - norm as well as in L ∞ - norm of the control variable. [ABSTRACT FROM AUTHOR]

This research work’s motive was to investigate the superfluity potential of the BCS-II drug (Dextromethorphan HBr) by solvent shift method to evaluate the impact of polymer gain factor on superfluity potential for the enhancement of bioavailability of orally prolonged release. To maintain the superfluity potential, different drug-release retarding polymers were used (HPMC 15cps, xanthan gum, sodium CMC) in a bio-relevant medium. The outcomes of this, reveal that all polymers remarkably enhanced the solubility of dextromethorphan HBr 1.07-2.49 fold when compared to those without polymer. HPMC and xanthan gum both at 0.1 % w/V showed excellent precipitation inhibitor's role at about 10.2-22.1 factor in SIFsp and 6.04-6.75 factor in PBS (pH 7.4). Elucidation of these results, show that HPMC (15cps) works on the parachute concept and Xanthan Gum on the glider concept. Hence, the superfluity potential is maintained by the selection of excellent polymers in non-formulated drugs to develop the superfluity formulation. [ABSTRACT FROM AUTHOR]

The authors have shown that errors in the values of indicator importance coefficients that characterize the system of interest can influence solutions obtained by multicriteria methods (alternative ranking and formation of their kernel). Assessing the stability of these solutions is an essential component of conclusions about the practical applicability of recommendations developed on their basis. The authors have proposed an approach to assessing the stability and used it in several examples of calculations. This approach increases the validity of the results of solving multicriteria problems by providing sufficiently objective basis for conclusions regarding their stability. [ABSTRACT FROM AUTHOR]

The authors show that the solutions obtained by multi-criteria methods (ranking of alternatives and formation of their core) can be affected by errors of the values of the importance ratio of the indicators that characterize the system under study. The stability analysis of such solutions is shown to be an important component of the conclusions about the possibility of practical use of the recommendations developed on their basis. The stability analysis approach is proposed and used in several examples of calculations. This approach will increase the substantiation of the results of the solution of multi-criteria problems due to obtaining a sufficiently objective basis for the conclusion on their stability. [ABSTRACT FROM AUTHOR]

[Display omitted] Interactions between biomolecules are ubiquitous in nature and crucial to many applications including vaccine development; environmentally friendly textile detergents; and food formulation. Using small angle X-ray scattering and structure-based molecular simulations, we explore protein–protein interactions in dilute to semi-concentrated protein solutions. We address the pertinent question, whether interaction models developed at infinite dilution can be extrapolated to concentrated regimes? Our analysis is based on measured and simulated osmotic second virial coefficients and solution structure factors at varying protein concentration and for different variants of the protein Thermomyces Lanuginosus Lipase (TLL). We show that in order to span the dilute and semi-concentrated regime, any model must carefully capture the balance between spatial and orientational correlations as the protein concentration is elevated. This requires consideration of the protein surface morphology, including possible patch interactions. Experimental data for TLL is most accurately described when assuming a patchy interaction, leading to dimer formation. Our analysis supports that the dimeric proteins predominantly exist in their open conformation where the active site is exposed, thereby maximising hydrophobic attractions that promote inter-protein alignment. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) remains a life-threatening infection, and it is well-known that effective TB treatment is associated with multiple drugs administered to infected patients on a daily basis. Terizidone (TZD) is an anti-TB drug used in the treatment of multi-drug resistant and extensively drug-resistant TB but presents with polyneuropathic adverse effects in some patients. To counteract these adverse effects, TZD is typically prescribed with pyridoxine (PDX), well known as Vitamin B6. As part of a pre-formulation study investigating the potential to co-formulate these two compounds, it became necessary to have a simple and reliable reversed-phase high-performance liquid chromatography (RP-HPLC) method. Optimal, simultaneous separation and detection of TZD and PDX were obtained using an isocratic mobile phase setup, consisting of ultrapure water and acetonitrile (30:70% v/v), with 1 mL glacial acetic acid added to the mobile phase mixture. A Discovery® C18, 150 × 4.6 mm, 5 μm column maintained at ambient temperature was utilized, with a detection wavelength of 260 nm. The method was validated in terms of linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), specificity, robustness, and solution stability. Validation proved this method to be acceptable and reliable for the simultaneous accurate detection and quantification of TZD and PDX.

This study was aimed at evaluating the solubility and solution stability of a cocrystal form of carbamazepine with cinnamic acid in the presence of sodium dodecyl sulfate (SDS) as surfactant and polyvinyl pyrrolidone K17 (PVP) as polymer in the aqueous medium. The solubilities of carbamazepine and cinnamic acid, as well as that of cocrystal, were evaluated in various media including phosphate buffer solution (PBS) (pH 6.8), SDS at 0.5 and 2% concentration, and PVP at 0.5, 1, and 2% concentration. Carbamazepine–cinnamic acid cocrystal was more soluble than carbamazepine alone in PBS. Solubility and solution stability of cocrystal were improved by PVP and SDS. At high SDS concentration (2%), solubility of cocrystal is less than carbamazepine because of preferential solubilization of the drug despite increase of solution stability. Thus, SDS and PVP significantly influence the solubility and solution stability of carbamazepine–cinnamic acid cocrystal, which should be taken into account in developing cocrystal formulations. [ABSTRACT FROM AUTHOR]

Abstract Background The stability-indicating chromatographic method was developed and validated for simultaneous estimation of telmisartan and rosuvastatin calcium in bulk and in tablet dosage form. The RP-HPLC elution was carried out at 242.0 nm using column Oyster ODS3 (150 × 4.6 mm, 5 µm) isocratically, and a mobile phase containing 10 mM phosphate buffer with 1.1 g octane-1-sulfonic acid sodium salt having pH 2.5 (adjusted with 5% OPA) and acetonitrile, with a proportion of 500:500, v/v was pumped through the column maintained at ambient (about 25 °C) temperature with 1.0 mL/min flow rate. The proposed method was validated according to ICH Q2 (R1) guideline. Results Telmisartan and rosuvastatin were eluted at 2.553 min and 4.505 min, respectively. The method is linear from 99.9073 to 299.7218 µg/mL for telmisartan (R 2 = 1.000) and 23.6841 – 71.0522 µg/mL for rosuvastatin (R 2 = 0.999). The average recovery percentage was found 100.51, 99.76, and 99.14% for telmisartan and 99.68, 99.72, and 98.56% for rosuvastatin at three different levels. Results of method repeatability and intermediate precision were found within acceptable limits. Results of solution stability showed that mobile phase was stable for 2 days; standard and sample preparations are stable for 1 day at room temperature as well as in the refrigerator (2–8 °C). Also, forced degradation study results show that method is stability indicating as capable of distinguishing the active analytes peak from the degraded product. Conclusion The developed stability-indicating method is linear in studied concentration range as well as precise, accurate, specific, and robust. Hence, successfully this method can be used for routine analysis and stability study. Graphical abstract

This paper deals with stability of solution map to a parametric control problem governed by semilinear elliptic equations with finite unilateral constraints, where the objective functional is not convex. By using the first-order necessary optimality conditions, we derive some sufficient conditions under which the solution map is upper semicontinuous with respect to parameters. [ABSTRACT FROM AUTHOR]

Solution processing of perovskite solar cells (PSCs) is highly promising for the high‐throughput production of cost‐effective devices. Although PSCs have achieved great advances in power conversion efficiency, challenges still remain in the reproducibility of high‐quality perovskite thin film with simultaneously improved precursor solution stability. Here, a reactive inhibition strategy by introducing diethyl (hydroxymethyl) phosphonate (DHP) in perovskite precursor solution is successfully employed to improve the stability of precursor solution and the performance of corresponding device. DHP inhibits the reactivity of the iodide and formamidinium ions through multiple chemical bonds, ensuring the stability of the precursor solution. In addition, due to chelation interaction of Pb2+ with the oxygen of PO in DHP, the DHP in the perovskite film improves the film quality with desired stoichiometry by reducing the defects and the content of lead iodide. The DHP‐doped precursor solution and corresponding devices show excellent performance reproducibility and super stability under ambient conditions for more than 50 days, which illustrates the commercial feasibility for scalable fabrication. [ABSTRACT FROM AUTHOR]

The paper studies the solution stability of a parametric control problem governed by semilinear elliptic equations with a mixed state-control constraint, where the objective function is nonconvex and the admissible set is unbounded. We show that under certain conditions, the solution set is upper semicontinuous and continuous with respect to parameters. [ABSTRACT FROM AUTHOR]

• Rh3+ speciation and aquation kinetics depend strongly on the presence of chloride. • UV–vis spectral trends of the Rh3+ complex correlate with electrochemistry. • Rh3+ reduction onset potential determined from cathodic linear sweep voltammograms. • Electrochemical quartz crystal microbalance used to quantify metallic Rh deposition. For back end of line metallization, the wet-chemical deposition of Rh requires investigation as the metal can improve the performance of semiconductor devices, due to its low resistivity and expected favourable electromigration characteristics. This study reports the Rh electrochemistry features in four background electrolytes (KCl, NH 4 Cl, K 2 SO 4 , and (NH 4) 2 SO 4) as well as the stability of Rh3+ in the electrolytes and ultrapure water using UV–vis spectroscopy and it was found that various complexes were formed depending on storage time and mixing time. The onset potentials of the Rh3+ reduction reaction(s) and hydrogen evolution reaction were determined by linear sweep voltammetry. For chloride-based solutions, a much slower stabilization was observed than for sulphate-based solutions, as evidenced by the gradual disappearing of multiple reduction peaks over the course of days. After stabilization, Rh is deposited with a single reduction peak. Although Rh has a high catalytic activity for hydrogen evolution, the adsorption/desorption of hydrogen ions on the metal surface and the onset of Rh3+ reduction occur at well-separated potentials, which allowed us to use an electrochemical quartz crystal microbalance to determine the Rh deposition potential as well as quantify the amount of metal deposited on a Pt-coated electrode. [ABSTRACT FROM AUTHOR]

In the presented work, a study on the solubility and intermolecular interactions of l -serine and L-cysteine was carried out in binary mixtures of H 2 O + dimethylformamide (DMF), H 2 O + dimethylsulfoxide (DMSO), and H 2 O + acetonitrile (ACN) in the temperature range of T = 288.15 K to 308.15 K. l -serine exhibited the highest solubility in water, while L-cysteine was more soluble in water-DMF. The solvation process was assessed through standard Gibbs energy calculations, indicating the solvation stability order: water-ACN > water-DMSO > water-DMF for l -serine, and water-DMF > water-DMSO > water-ACN for L-cysteine. This study also explored the influence of these amino acids on solvent–solvent interactions, revealing changes in chemical entropies and self-association patterns within the binary solvent mixtures. Variation of solubility of L-cysteine in Water-DMF in various mole fraction concentrations of DMF (X DMF) with temperature (K). [Display omitted] • l-serine shows highest solubility in water, generally decreasing with organic components, except water-ACN solvent system. • L-cysteine is more soluble in water-DMF, solubility order: water-DMF > water-DMSO > water-ACN. • Standard Gibbs energy calculations reveal l -serine's stability: most in water-DMSO, least in water-ACN. • Non-covalent interactions govern stability, l -serine's solvation most affected by DMF, while L-cysteine by ACN. [ABSTRACT FROM AUTHOR]

Herein, the effect of material inhomogeneity on the temperature and stress distributions in functionally graded solids is analyzed. Assuming the inaccessibility of the inner surface of a multilayer functionally graded hollow sphere for the direct monitoring of the temperature in real time, the problem on identifying the temperature on this surface is formulated by implementing the temperature and circumferential strain given on the outer surface. The material properties within each sphere layer are assumed to be arbitrary functions of the radial coordinate. By representing the material properties of the sphere in the form of stepwise‐variable functions and implementing the generalized derivative technique, a method for the reduction of the formulated problem to an inverse thermoelasticity problem is developed. Using the finite difference method, a numerical algorithm for solving the inverse problem is suggested. The stability of the proposed numerical algorithm concerning the input perturbation is verified. [ABSTRACT FROM AUTHOR]

We consider the problem of localization of magnetic field sources in magnetocardiography using the 1D multidipole model. In real conditions, the experimenter has to deal with an underdetermined, ill-conditioned system. Regularizing procedures were used to obtain a stable solution. The work investigates the resolution of the method, the reconstruction quality (determining the spatial parameters of a multidipole: the depth and amplitude of the dipole moment) and the stability of the solution. The computer simulation used the singular value matrix decomposition method and Tikhonov regularization. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) remains a life-threatening infection, and it is well-known that effective TB treatment is associated with multiple drugs administered to infected patients on a daily basis. Terizidone (TZD) is an anti-TB drug used in the treatment of multi-drug resistant and extensively drug-resistant TB but presents with polyneuropathic adverse effects in some patients. To counteract these adverse effects, TZD is typically prescribed with pyridoxine (PDX), well known as Vitamin B6. As part of a pre-formulation study investigating the potential to co-formulate these two compounds, it became necessary to have a simple and reliable reversed-phase high-performance liquid chromatography (RP-HPLC) method. Optimal, simultaneous separation and detection of TZD and PDX were obtained using an isocratic mobile phase setup, consisting of ultrapure water and acetonitrile (30:70% v/v), with 1 mL glacial acetic acid added to the mobile phase mixture. A Discovery® C18,150 X 4.6 mm, 5 |im column maintained at ambient temperature was utilized, with a detection wavelength of 260 nm. The method was validated in terms of linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), specificity, robustness, and solution stability. Validation proved this method to be acceptable and reliable for the simultaneous accurate detection and quantification of TZD and PDX. [ABSTRACT FROM AUTHOR]

Half‐sandwich RuII complexes, [(YZ)RuII(η6‐arene)(X)]+, (YZ=chelating bidentate ligand, X=halide), with N,N and N,O coordination (1–9) show significant antiproliferative activity against the metastatic triple‐negative breast carcinoma (MDA‐MB‐231). 3‐aminobenzoic acid or its methyl ester is used in all the ligands while varying the aldehyde for N,N and N,O coordination. In the N,N coordinated complex the coordinated halide(X) is varied for enhancing stability in solution (X=Cl, I). Rapid aquation and halide exchange of the pyridine analogues, 2 and 3, in solution are a major bane towards their antiproliferative activity. Presence of free −COOH group (1 and 4) make complexes hydrophilic and reduces toxicity. The imidazolyl 3‐aminobenzoate based N,N coordinated 5 and 6 display better solution stability and efficient antiproliferative activity (IC50 ca. 2.3–2.5 μM) compared to the pyridine based 2 and 3 (IC50>100 μM) or the N,O coordinated complexes (7–9) (IC50 ca. 7–10 μM). The iodido coordinated, 6, is resistant towards aquation and halide exchange. The N,O coordinated 7–9 underwent instantaneous aquation at pH 7.4 generating monoaquated complexes stable for at least 6 h. Complexes 5 and 6, bind to 9‐ethylguanine (9‐EtG) showing propensity to interact with DNA bases. The complexes may kill via apoptosis as displayed from the study of 8. The change in coordination mode and the aldehyde affected the solution stability, antiproliferative activity and mechanistic pathways. The N,N coordinated (5 and 6) exhibit arrest in the G2/M phase while the N,O coordinated 8 showed arrest in the G0/G1 phase. [ABSTRACT FROM AUTHOR]

A stability indicating RP-HPLC method has been developed for quantification of Cilnidipine in bulk and in tablet dosage form. The chromatographic analysis was accomplished at ambient temperature on Xttera RP18 (100 x 4.6 mm, 3.5 μm) column and 1 mL/min flow rate by using Eluent composed of 10 mM phosphate buffer pH 2.6 with Acetonitrile (300:700, v/v). The UV detection at the wavelength of 240 nm was carried out using 20 μL injection volume. The Cilnidipine retention time was found to be 3.029 minute. The method in the range of 40.0573-120.1719 μg/mL was found to be linear (R² = 0.999) with a detection limit and quantitation limit of 1.2038 and 3.6478 μg/mL, respectively. The mean recovery% over the three tested levels of 50, 100 and 150% were found to be 98.74, 99.60, and 98.23%, respectively. The mean %assay of 99.29 for method repeatability and 98.82 for intermediate precision were found with %RSD of 0.68 and 0.31, respectively. Cilnidipine drug substance and their product exposed to acid, alkali, oxidative, thermal, photolytic and humidity stress conditions. The acid, alkali and photolytic induced stress studies signifying the formation of a variety of degradants and their peaks were well resolved from that of active analyte peak. Hence, it is recommended that the Cilnidipine drug substance, as well as drug product, should be store in a tightly closed container protected from light. The method as per ICH guidelines was validated for specificity, linearity, detection limit, quantitation limit, precision, accuracy, robustness, solution stability, and can be effectively used for routine analysis. [ABSTRACT FROM AUTHOR]

Bis(pinacolato)diboron (B2Pin2) is a common reagent used to prepare pinacolboronate esters for Suzuki-Miyaura coupling reactions in pharmaceutical syntheses. As a known mutagenic impurity, it is challenging to develop analytical methods for the determination of B2Pin2 due to its low control limit, high reactivity, and lack of chromophore. Here, we report a generic liquid chromatography (LC)- mass spectrometry (MS) method to monitor B2Pin2 at low parts per million (ppm) levels in pharmaceutical compounds by single ion monitoring. Ammonium acetate (0.5 mM) was added in the mobile phases to form B2Pin2 gas-phase ammonium adduct, which eliminated MS instrumentation variances and achieved a quantification limit (QL) better than 10 ng/mL (corresponding to 1 ppm in substrate at 10 mg/mL) with optimized LC conditions. To accommodate diverse solubility profiles of pharmaceutical compounds, three diluents including acetonitrile, stabilized tetrahydrofuran, and dimethyl sulfoxide were recommended as the primary diluents based on B2Pin2 solution stability. Three alternative diluents with additives were proposed as backups. Three Bristol Myers Squibb compounds that required B2Pin2 control were spiked with 1–20 ppm B2Pin2 as the case studies. The QLs for all three materials were better than 1 ppm and the recovery values were within 100 ± 20% at 1, 10, and 20 ppm spiked levels.

This paper studies local stability of a parametric optimal control problem governed by semilinear elliptic equations with mixed pointwise constraints. We show that if the unperturbed problem satisfies the strictly nonnegative second-order optimality conditions, then the solution map is upper Hölder continuous in L ∞ -norm of control variable. [ABSTRACT FROM AUTHOR]

This paper studies solution stability of a parametric optimal control problem governed by semilinear elliptic equations and nonconvex objective function with mixed pointwise constrains in which the controls act both in the domain and on the boundary. We give sufficient conditions under which the solution map is upper semicontinuous and continuous in parameters. [ABSTRACT FROM AUTHOR]

RP-HPLC method has been developed along with stability indicating attribute for simultaneous estimation of Metoprolol Succinate and Chlorthalidone in bulk and in tablet dosage form with minimized drug extraction steps. The chromatographic analysis was performed isocratically by using Oyster ODS3, 150-4.6 mm column having particle size of 5 µm (Merck & Co.) as stationary phase maintained at ambient temperature (about 25°C) with 1.0 mL/min of flow rate and 20 mM phosphate buffer having pH 2.3 (adjusted with10% orthophosphoric acid) and Acetonitrile (650:350, v/v) as Eluent at wavelength 225 nm. Individual drug substances as well as combination drug product was subjected to acid, alkali, oxidative, photolytic, thermal and humidity degradation, the peaks due to degraded product were significantly separated out from active analytes peak. The method was validated for the specificity, linearity, detection limit, quantitation limit, precision, accuracy, robustness and solution stability as per ICH guidelines and successfully used for regular analysis. [ABSTRACT FROM AUTHOR]

This commentary highlights the significance of the solution stability and preparation of a solution of cocrystal in evaluating anti-tumor activity. It introduces a challenging issue regarding improving the biological activity of an API in cocrystal form. [ABSTRACT FROM AUTHOR]

Solution speciation of Rh(η5-C5Me5), Ru(η6-p-cymene) and Ru(η6- toluene) complexes of 2,4-pyridinedicarboxylic acid (2,4-dipicH2) was studied and compared to that of 2-picolinic acid (picH) in addition to their reactivity towards chloride and bromide ions, 1-methylimidazole and guanosine. Structures of [Rh(η5- C5Me5)(2,4-dipicH)Cl] ·3H2O (1), 2[Ru(η6-toluene)(2,4-dipicH) Cl] ·3H2O (2) and [Ru(η6-toluene)(2,4-dipic)]3 ·7H2O (3) were analyzed by X-ray diffraction. 1 and 2 show typical piano stool geometry, while 3 is a triangular complex stabilized via the monodentate coordination of the second carboxylate group to the neighboring Ru(II) center. High stability [M(arene)L(H2O/Cl)] species predominate at pH 7.4. 2,4-Dipic forms more stable complexes with Ru(η6-arene) than pic, with this difference being minor in the case of the Rh(η5-C5Me5) complexes. A lower affinity of 2,4-dipic complexes to halide ions was found compared to the corresponding pic complexes due to the additional COO- moiety. [ABSTRACT FROM AUTHOR]

The instability of the perovskite precursor solution seriously affects the purity of the perovskite films, which is one of the key factors for the low reproducibility for highly efficient devices. Formamidinium‐based perovskite with more suitable spectral absorption range and higher thermal stability has become the mainstream material. However, the side reactions in pure formamidinium lead iodide solution have not been fully revealed. Herein, it is demonstrated that self‐condensation of formamidinium iodide occurs to form the by‐product s‐triazine, and its content increases with the aging time of the solution. It is also discovered that phenylboric acid (PBA) can effectively inhibit the self‐condensation reaction and the content of the s‐triazine is decreased by more than 95% in the solution aging at 60 °C for 7 days. The PBA used as the stabilizer not only enhances purity and decreases defect density of the perovskite films but also strongly enhances the reproducibility for highly efficient perovskite solar cells. [ABSTRACT FROM AUTHOR]

An attempt has been made to construct models that approximate the time-range statistical properties of the useful inflow into Lake Baikal and its relationships with potential predictors that permit predictive assessments to be obtained. The problem solution consists of two parts. In the first part, the constructed physical and statistical models record the known patterns of runoff from the catchment. These patterns are subject to significant regression relationships between the predicted value of the monthly inflow and its hydrometeorological predictors. These models can be used to forecast the average useful inflow for the next month. The predictive correction for interannual variability to the seasonal inflow wave in these models is based on variability in the predictor values that are known at the forecasting time. The second part of the research is focused on possible trends and cycles in the interannual variability in useful inflow in the most water-abundant third quarter in order to predict it with a lead time of 1 year or more. Various cycle models with parameters estimated using the training sampling set do not provide a stable solution in the control sampling set. The best result has been obtained by a cyclical model with fixed periods, which records the possible impact on the inflow variability provided by gravitational influence of the Moon and major planets on the Earth and the Sun. Nevertheless, this model also should not be considered statistically significant due to the small proportion of the explainable variance and insufficiency of the data on useful inflow into Baikal. [ABSTRACT FROM AUTHOR]

In this paper, we establish lower and upper error bounds for strongly pseudomonotone equilibrium problems with and without Lipschitz condition. Our results generalize and improve some existing results in the literature. Also, we prove the stability of the projection method for this class of problems. The final error of the algorithm can be evaluated through the upper bound of errors in its steps. Some numerical experiments are presented to illustrate the obtained results. [ABSTRACT FROM AUTHOR]

This study investigated the effects of different concentrations (0, 5, 10, 20, 50, and 100 μmol/g protein) of tea polyphenols (TP) on the oxidative modification and the physicochemical, structural, and gelling properties of myofibrillar protein (MP) from grass carp (Ctenopharyngodon idellus) oxidized by a hydroxyl radical-generating system. The results showed that low concentrations (5 and 10 μmol/g protein) of TP could effectively inhibit the formation of carbonyl groups and dityrosine, the loss of sulfhydryl groups and α-helix conformation, and the change of the tertiary structure of MP caused by hydroxyl radicals. Moreover, the presence of TP in all concentrations decreased the surface hydrophobicity of MP. TP at 10 μmol/g protein had better effects on preventing the oxidation-induced cross-linking and aggregation of myosin heavy chain (MHC) and actin of MP, keeping the stability of MP solutions with lower turbiscan stability index (TSI) values, and improving gelling properties characterized by higher hardness and gel strength of MP gels. By contrast, excessive presence of TP (20, 50, and 100 μmol/g protein) showed pro-oxidative effects on oxidatively stressed MP, which was detrimental to the MP and contributed to the denaturation and irregular aggregation of MP, the loss of MP solution stability, and lower gelling capacity with poor texture and gel strength. The concentration-dependent effects of TP on MP depended on the extent of MP oxidative modification and MP-TP interactions, indicating that a proper amount of TP has the potential to protect MP from oxidation and to enhance the gelling capacity of surimi during processing. [ABSTRACT FROM AUTHOR]

Upper semicontinuous (usc) functions arise in the analysis of maximization problems, distributionally robust optimization, and function identification, which includes many problems of nonparametric statistics. We establish that every usc function is the limit of a hypo-converging sequence of piecewise affine functions of the difference-of-max type and illustrate resulting algorithmic possibilities in the context of approximate solution of infinite-dimensional optimization problems. In an effort to quantify the ease with which classes of usc functions can be approximated by finite collections, we provide upper and lower bounds on covering numbers for bounded sets of usc functions under the Attouch-Wets distance. The result is applied in the context of stochastic optimization problems defined over spaces of usc functions. We establish confidence regions for optimal solutions based on sample average approximations and examine the accompanying rates of convergence. Examples from nonparametric statistics illustrate the results. [ABSTRACT FROM AUTHOR]

Al2O3-ZrO2 microspheres were prepared by internal gelation method. The effects of Al3+ on the stability of solution and performance of gel spheres were studied. Al3+ had a great influence on the stability of the solutions, and the more of the amount of Al3+, the shorter of the stabilization time. Because Al3+ did not copolymerize with Zr4+ during the sol-gel transformation, the strength of gel sphere added with Al3+ was low and deformed easily as it was squeezed. The results of our experiments well verify Glasser team's speculation and conclusions. At the same time, based on the experimental results, we prepared Al2O3-ZrO2 composite microspheres with higher content of Al2O3 by controlling the pH of the solution. The change curve of viscosity with time and the stabilization time of the solution with different Al3+ dosage were given, which could provide references for industrial mass production. Samples without hydrothermal treatment cracked severely, while the samples hydrothermally treated kept structural integrity with no cracks after calcined. Al2O3-ZrO2 microspheres with no segregation and phase separation were prepared and alumina evenly distributed in the zirconia matrix. When the content of Al2O3 was low, the tetragonal phase was stable. And the cubic phase was obtained when the content of Al2O3 was more. [ABSTRACT FROM AUTHOR]

This paper studies the local stability of a parametric optimal control problem with mixed pointwise constraints. We show that if the unperturbed problem satisfies the strictly second-order optimality conditions, then the solution map is upper Hölder continuous in L∞-norm of control variable. [ABSTRACT FROM AUTHOR]

Aims: Due to their significant biological activity, thiosemicarbazones (TSCs) are promising candidates for anticancer therapy. In part, the efficacy of TSCs is linked to their ability to chelate essential metal ions such as copper and iron. Triapine, the best-studied anticancer TSC, has been tested clinically with promising results in hematological diseases. During the past few years, a novel subclass of TSCs with improved anticancer activity was found to induce paraptosis, a recently characterized form of cell death. The aim of this study was to identify structural and chemical properties associated with anticancer activity and paraptosis induction of TSCs. Results: When testing a panel of structurally related TSCs, compounds with nanomolar anticancer activity and paraptosis-inducing properties showed higher copper(II) complex solution stability and a slower reduction rate, which resulted in reduced redox activity. In contrast, TSCs with lower anticancer activity induced higher levels of superoxide that rapidly stimulated superoxide dismutase expression in treated cells, effectively protecting the cells from drug-induced redox stress. Innovation: Consequently, we hypothesize that in the case of close Triapine derivatives, intracellular reduction leads to rapid dissociation of intracellularly formed copper complexes. In contrast, TSCs characterized by highly stable, slowly reducible copper(II) complexes are able to reach new intracellular targets such as the endoplasmic reticulum-resident protein disulfide isomerase. Conclusion: The additional modes of actions observed with highly active TSC derivatives are based on intracellular formation of stable copper complexes, offering a new approach to combat (drug-resistant) cancer cells. [ABSTRACT FROM AUTHOR]

• Electrodeposition and sodium dithionite reduction for gold recovery was compared. • Gold began to deposit at the potential of lower than −100 mV Hg/HgO. • Cl−, S 2 O 3 2− and SO 3 2− exhibited different effects on gold deposition/reduction. • Sodium dithionite reduction displayed better gold recovery performance. • Sodium dithionite reduction had better solution stability and lower recovery cost. A comparative study was performed on electrodeposition and sodium dithionite reduction for recovering gold in the gold-rich solution from the adsorption of thiosulfate solution by ion exchange resin. Using electrodeposition method, gold started to deposit when the potential was lower than −100 mV Hg/HgO. The rise of Cl− concentration improved gold deposition while the increases of SO 3 2− and S 2 O 3 2− concentrations were unbeneficial to gold deposition. When the solution was deposited at the optimum potential of −600 mV Hg/HgO for 5 h, the gold deposition percentage reached 99.33 %. With sodium dithionite reduction method, the gold reduction percentage achieved 100 % after only 5 min as S 2 O 4 2− dosage was eight times of the theoretical amount. The increases of SO 3 2− and S 2 O 3 2− concentrations hindered gold reduction while the augment of Cl− concentration had no obvious effect. Overall, sodium dithionite reduction method has the advantages of shorter reaction time, higher gold recovery percentage, better solution stability and lower recovery cost, and thus it has a broader industrial application prospect. [ABSTRACT FROM AUTHOR]

Water-soluble cellulose ethers are widely used as stabilizers, thickeners, and viscosity modifiers in many industries. Understanding rheological behavior of the polymers is of great significance to the effective control of their applications. In this work, a series of cyanoethylcellulose (CEC) samples with different molecular weights were prepared with cellulose and acrylonitrile in NaOH/urea aqueous solution under the homogeneous reaction. The rheological properties of water-soluble CECs as a function of concentration and molecular weight were investigated using shear viscosity and dynamic rheological measurements. Viscoelastic behaviors have been successfully described by the Carreau model, the Ostwald-de-Waele equation, and the Cox–Merz rule. The entanglement concentrations were determined to be 0.6, 0.85, and 1.5 wt% for CEC-11, CEC-7, and CEC-3, respectively. All of the solutions exhibited viscous behavior rather than a clear sol-gel transition in all tested concentrations. The heterogeneous nature of CEC in an aqueous solution was determined from the Cox–Merz rule due to the coexistence of single chain complexes and aggregates. In addition, the CEC aqueous solutions showed good thermal and time stability, and the transition with temperature was reversible.

In this work, the various biological activities of eight organoruthenium(II) complexes were evaluated to reveal correlations with their stability and reactivity in aqueous media. Complexes with general formula [Ru(η6-p-cymene)(X,Y)(Z)] were prepared, where (X,Y) represents either an O,O-ligand (β-diketone), N,O-ligand (8-hydroxyquinoline) or O,S-pyrithione-type ligands (pyrithione = 1-hydroxypyridine-2(1H)-thione) with Cl− or 1,3,5-triaza-7-phosphaadamantane (PTA) as a co-ligand (Z). The tested complexes inhibit the chlamydial growth on HeLa cells, and one of the complexes inhibits the growth of the human herpes simplex virus-2. The chlorido complexes with N,O- and O,S-ligands displayed strong antibacterial activity on Gram-positive strains including the resistant S. aureus (MRSA) and were cytotoxic in adenocarcinoma cell lines. Effect of the structural variation on the biological properties and solution stability was clearly revealed. The decreased bioactivity of the β-diketone complexes can be related to their lower stability in solution. In contrast, the O,S-pyrithione-type complexes are highly stable in solution and the complexation prevents the oxidation of the O,S-ligands. Comparing the binding of PTA and the chlorido co-ligands, it can be concluded that PTA is generally more strongly coordinated to ruthenium, which at the same time decreased the reactivity of complexes with human serum albumin or 1-methylimidazole as well as diminished their bioactivity.