Transport of Lead (Pb<Superscript>2+</Superscript>) Ions Through Silty-Clayey Soils Under Acidic Conditions

This study aimed to identify effects of pH on the transport of Pb²⁺ ions through a saturated silty-clayey soil layer by using advection–dispersion equation (ADE). The predictive accuracy of the solution of ADE depends on the proper determination of the retardation by adsorption and, therefore, the adsorption mechanism of lead onto silty-clayey soil was investigated first by performing batch equilibrium experiments. These results showed that the sorption mechanism of lead onto silty-clayey soil depended on pH and could be best described by the Langmuir isotherm. Based on the results of the sequential experiments, it was also concluded that the pH dependent charges in silty-clayey soil were mainly associated with the surfaces of carbonates and the specific adsorption of lead ions. The numerical solutions of the combined form of ADE with the Langmuir isotherm indicated that the migration profiles of lead in silty-clayey soil were a strong function of the parameters of the Langmuir isotherm rather than the infiltration velocity.     

N,N'-disalicylidene-1,3-diaminopropane as a selective chelating titrant for copper(II)

This study was carried out to develop a new complexometric titration method for determination of copper. For this purpose, the standard solutions of copper(II) (10(-3)-10(-5) M) were potentiometrically titrated using N,N'-disalicylidene-1,3-diaminopropane (Schiff base) as titrant and copper(II)-selective electrode for end-point indication in both ammonium acetate and ammonia/ammonium chloride buffer media. The stoichiometry of titration reaction and interference effects of some metal ions on titration of copper were discussed. There was a good agreement between the results obtained by the proposed titration method and ethylenediaminetetraacetic acid (EDTA) titration method. The accuracy and precision of Schiff base method were tested by five replicate determinations both on the standard solution of copper(II) and standard reference materials. The results have indicated that the percentage of copper in alloys can be safely determined by using the Schiff base method without interference from many other metals in alloys.     

Photochemical reactions of M(CO)5THF (M = Cr, Mo, W) with thio Schiff bases

The hitherto unknown complexes, [M₂(CO)₆(μ-CO)(μ-L)], [M = Cr; 1, Mo; 2, W; 3] and [M₂(CO)₆(μ-CO)(μ-L′)], [M = Cr; 4, Mo; 5, W; 6] have been synthesized by the photochemical reactions of photogenerated intermediate, M(CO)₅THF (M = Cr, Mo, W) with thio Schiff base ligands, N,N′-bis(2-aminothiophenol)-1,4-bis(2-carboxaldehydephenoxy)butane (H ₂ L) and N,N′-bis(2-aminothiophenol)-1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane (H ₂ L′). The complexes have been characterized by elemental analysis, LC-mass spectrometry, magnetic studies, FT-IR and ¹H NMR spectroscopy. The spectroscopic studies show that H ₂ L and H ₂ L′ ligands are converted to benzothiazole derivatives, L and L′ after UV irradiation and coordinated to the central metal as bridging ligands via the central azomethine nitrogen and sulphur atoms in 1–6.     

Scheduling the adjuvant endocrine therapy for early stage breast cancer

Based on the data available through published trial results, we build a mixed integer nonlinear programming (MINLP) model in order to find an optimal treatment plan for a given HR+ early stage breast cancer patient who is postmenopausal. The objective is to maximize the disease-free survival percentage at the end of the treatment period subject to the constraints on the risk of contralateral breast cancer and the risks of several side effects, including endometrial cancer, thromboembolic events, cardiovascular diseases, bone fractures, hot flushes, and vaginal bleeding. The results of numerical experiments suggest the effectiveness of some of the schedules currently used in practice, as well as suggest some attractive alternative treatment plans.     

A novel,rapid and sensitive UPLC–MS/MS method for the determination of macitentan in patients with pulmonary arterial hypertension

Macitentan is an endothelin receptor antagonist commonly used in the treatment of pulmonary arterial hypertension (PAH). A novel, rapid, simple and sensitive UPLC–MS/MS method was developed and validated for pharmacokinetic study and the determination of macitentan in PAH patients. Macitentan and bosentan, which are used as internal standards, were detected using atmospheric pressure chemical ionization in positive ion and multiple reaction monitoring mode by monitoring the mass transitions m/z 589.1 → 203.3 and 552.6 → 311.5, respectively. Chromatographic separation was performed on a reverse‐phase C18 column (5 μm, 4.6 × 150 mm) with an isocratic mobile phase, which consisted of water containing 0.2% acetic acid–acetonitrile (90:10, v/v) at a flow rate of 1 mL/min. Retention times were 1.97 and 1.72 min for macitentan and IS, respectively. The calibration curve with high correlation coefficient (0.9996) was linear in the range 1–500 ng/mL. The lower limit of quantitation and average recovery values were determined as 1 ng/mL and 89.8%, respectively. This method is the first UPLC–MS/MS method developed and validated for the determination of macitentan from human plasma. The developed analytical method was fully validated for linearity, selectivity, specificity, accuracy, precision, sensitivity, stability, matrix effect and recovery according to US Food and Drug Administration guidelines. The developed method was applied successfully for pharmacokinetic study and the determination of macitentan in PAH patients.     

Removal of methylene blue dye from aqueous solution by semi‐interpenetrating polymer network hybrid hydrogel: Optimization through Taguchi method

In this study, sodium humate/poly(acrylamide‐co‐methacrylic acid)/kaolin semi‐interpenetrating polymer network hybrid hydrogel was synthesized as an effective adsorbent for the removal of methylene blue. The morphological and structural properties, and swelling behavior in distilled water and various environments of hybrid hydrogel were investigated with different analyses and tests. The equilibrium swelling percent of hybrid hydrogel reached to 37,000% in 240 min. The parameters (agitation time, concentration, dose, temperature, and pH) affecting adsorption process for methylene blue were optimized using Taguchi method. The data obtained in optimum conditions were well fitted to Langmuir adsorption isotherm and maximum adsorption capacity was determined as 833. 33 mg/g. In the light of the results, the utilization of hybrid hydrogel with high swelling capacity is foreseen as a favored adsorbent in several separation processes. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1070–1078     

A Cocatalyst that Stabilizes a Hydride Intermediate during Photocatalytic Hydrogen Evolution over a Rhodium‐Doped TiO2 Nanosheet

The hydrogen evolution reaction using semiconductor photocatalysts has been significantly improved by cocatalyst loading. However, there are still many speculations regarding the actual role of the cocatalyst. Now a photocatalytic hydrogen evolution reaction pathway is reported on a cocatalyst site using TiO₂ nanosheets doped with Rh at Ti sites as one‐atom cocatalysts. A hydride species adsorbed on the one‐atom Rh dopant cocatalyst site was confirmed experimentally as the intermediate state for hydrogen evolution, which was consistent with the results of density functional theory (DFT) calculations. In this system, the role of the cocatalyst in photocatalytic hydrogen evolution is related to the withdrawal of photo‐excited electrons and stabilization of the hydride intermediate species; the presence of oxygen vacancies induced by Rh facilitate the withdrawal of electrons and stabilization of the hydride.     

Photoluminescence and Magnetism Study of Blue Light Emitting the Oxygen-Bridged Open-Cubane Cobalt(II) Cluster

A new cubane-based cobalt(II) cluster, [Co₄L₄] (1), where H₂L?=?2-((E)-(2-hydroxyethylimino) methyl)-4-chlorophenol has been prepared using a solvothermal process and characterized by structural, optical and magnetism. The crystal structure of 1 consists of a tetranuclear Co₄O₄ core in an open-cubane framework. Each cobalt(II) ion is penta-coordinated in a distorted square pyramidal geometry (τ_Co1=Co1i?=?0.030, τ_Co2=Co2i?=?0.023). Furthermore, the photoluminescence analysis indicates that 1 has a strong blue emission which should be attributed to coordination of the metal to the ligand. The temperature dependence of the magnetic susceptibilities of 1 shows antiferromagnetic coupling (J?=???26.61?±?0.01) between cobalt(II) ions.     

Synthesis, Structural Characterization and Chromotropism of a Ni(II) and a Co(II) Compound with Acesulfamate as a Ligand

The novel bis(acesulfamato-O)tetraaquanickel(II) and bis(acesulfamato-N)tetraaquacobalt(II) complexes have been synthesized and characterized by elemental analyses, magnetic measurements, u.v.–vis and FT-IR spectra. The thermal behavior of the complexes was also studied by simultaneous TG, DTG and DTA methods in a static air atmosphere. The crystal structure of bis(acesulfamato-O)tetraaquanickel(II) complex has been identified by single-crystal X-ray diffraction analyses. The acesulfamate ligand (acs) acts as an O-donor through the carbonyl oxygen as a monodentate ligand in the Ni(II) complex. The Ni(II) ion structure resides on a two-fold axis and is coordinated by four aqua ligands defining the basal plane, and by two monodentate acesulfamate ligands occupying the axial positions. The chromotropism of both complexes has been studied using thermal and spectral analysis. The bis(acesulfamato-N)tetraaquacobalt(II)complex is found to be very soluble in water and organic solvents and exhibits a reversible thermochromism from pink to violet depending on deaquation, which occurs in two steps, in the solid state. The bis(acesulfamato-O)tetraaquanickel(II) complex has shown two thermochromic properties one of which is a reversible and changes the color from green to yellow by an endothermic effect, whereas the other one is irreversible and changes from yellow to brown depending on deaquation, in the solid state. The bis(acesulfamato-N)tetraaquacobalt(II) complex exhibits solvatochromism in solvents with different donor number and ionochromism in the presence of various cations in solution.