"Core/Shell" Nanocomposites as Photocatalysts for the Degradation of the Water Pollutants Malachite Green and Rhodamine B.

"Core/shell" composites are based on a ferrite core coated by two layers with different properties, one of them is an isolator, SiO2, and the other is a semiconductor, TiO2. These composites are attracting interest because of their structure, photocatalytic activity, and magnetic properties. Nanocomposites of the "core/shell" МFe2O4/SiO2/TiO2 (М = Zn(II), Co(II)) type are synthesized with a core of MFe2O4 produced by two different methods, namely the sol-gel method (SG) using propylene oxide as a gelling agent and the hydrothermal method (HT). SiO2 and TiO2 layer coating is performed by means of tetraethylorthosilicate, TEOS, Ti(IV) tetrabutoxide, and Ti(OBu)4, respectively. A combination of different experimental techniques is required to prove the structure and phase composition, such as XRD, UV-Vis, TEM with EDS, photoluminescence, and XPS. By Rietveld analysis of the XRD data unit cell parameters, the crystallite size and weight fraction of the polymorphs anatase and rutile of the shell TiO2 and of the ferrite core are determined. The magnetic properties of the samples, and their activity for the photodegradation of the synthetic industrial dyes Malachite Green and Rhodamine B are measured in model water solutions under UV light irradiation and simulated solar irradiation. The influence of the water matrix on the photocatalytic activity is determined using artificial seawater in addition to ultrapure water. The rate constants of the photocatalytic process are obtained along with the reaction mechanism, established using radical scavengers where the role of the radicals is elucidated.

Investigation of the Sensing Properties of Lanthanoid Metal-Organic Frameworks (Ln-MOFs) with Terephthalic Acid.

The solvothermal synthesis of LnCl3.nH2O with terephthalic acid (benzene-1,4-dicarboxylic acid, H2BDC) produced metal-organic frameworks (LnBDC), [Ln2(BDC)3(H2O)4]∞, where Ln = Sm, Eu, Tb, and Dy. The materials obtained were characterized by a number of physico-chemical techniques. The influence of the ionic radius of the lanthanides on the microstructural characteristics of the Ln-MOFs was evaluated by performing Rietveld refinement. The MOFs obtained were tested as fluorescent sensors for numerous cations and anions in water. The highly luminescent EuBDC and TbBDC demonstrated multi-responsive luminescence sensing functions to detect Ag(I), Fe(III), Cr(III), and Cr(VI), which are essential for their environmental applications. By applying the non-linear Stern-Volmer equation, the fluorescent quenching mechanism was determined. The stability of the obtained materials in water in a wide pH range (acidity pH = 4 and alkalinity pH = 9 solutions) was confirmed.

Mixed Metal Oxides of the Type CoxZn1-xFe2O4 as Photocatalysts for Malachite Green Degradation Under UV Light Irradiation.

A combination of thermal and mechanical (high energy ball milling) treatment was applied in an attempt to obtain polycrystalline mixed metal binary and ternary oxides of the type CoxZn1-xFe2O4 (x = 0; 0.25; 0.5; 0.75; 1). The synthetic procedure used successfully produced single-phased, homogeneous ZnFe2O4, CoFe2O4, and Co0.75Zn0.25Fe2O4, as well as mixed oxides, whose composition depended both on the duration of the high energy ball milling and the ratio Zn(II)/Co(II). The formation of spinel-like structures was proved by XRD, Mössbauer spectroscopy and Raman spectroscopy. For the characterization of the samples low-temperature N2 adsorption, UV/Vis spectroscopy and transmission electron microscopy were applied. The energy band gap of the samples was calculated, suggesting they are promising photocatalysts. The decomposition of the Malachite Green in model water solutions under UV-light irradiation was successfully achieved in the presence of the samples as photocatalysts. The highest rate constant was obtained for the sample synthesized at longer milling time in combination with higher Zn(II)/Co(II) ratio. The photocatalytic activity of the ternary mixed oxides was compared with the pure hematite, α-Fe2O3, and the binary ZnFe2O4 and CoFe2O4 ferrites with spinel structure that were treated in the same way. A synergetic effect of α-Fe2O3 and the spinel-like structure on the photocatalytic properties of ternary mixed metal oxides was detected.

Synthesis, crystal structure and physico-chemical properties of 3,3'-[(4-hydroxyphenyl)methyl] bis-(4-hydroxy-2H-chromen-2-one).

The compound 3,3'-[(4-Hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one) was synthesized by the Knoevenagel reaction. Crystals, suitable for X-ray data collection, were grown by slow evaporation from an ethanol solution. The product 3,3'-[(4-Hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one) · ethanol crystallizes in the monoclinic system, space group P2(1)/n. The ultraviolet/visible absorption spectra in different solvents were recorded. Sensitivity of the compound to solvent polarity and hydrogen bonding with protic (ethanol, H(2)O) and aprotic (dimethylsulfoxide, acetonitrile) solvents was detected. Based on (1)H-NMR spectroscopy as well as on potentiometric and UV/vis titration experiments the acid dissociation constants for 3,3'-[(4-Hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one) were estimated.

Visible Light-Driven Photocatalytic Activity of Magnetic Recoverable Ternary ZnFe2O4/rGO/g-C3N4 Nanocomposites.

ZnFe2O4/rGO/g-C3N4 ternary nanocomposite photocatalysts with different ZnFe2O4/g-C3N4 weight ratio (0.5, 0.75, 1) were prepared by a stepwise solvothermal method using ethylene glycol as the solvent. Physicochemical methods such as X-ray diffraction, UV-Vis diffuse reflectance spectroscopy and photoluminescence spectroscopy were applied in order to characterize the composites. The formation of a meso-/macroporous structure with specific surface area between 67 and 77 m2 g?1 was confirmed by N2 adsorption/desorption. The bandgap of the composites was found to be lower (2.30 eV) than that of g-C3N4 (2.7 eV). In contrast to pure g-C3N4, the composites showed no fluorescence, i.e. no recombination of e?/h+ took place. All samples, including pure g-C3N4 and ZnFe2O4, were tested for adsorption and photocatalytic degradation of aqueous malachite green model solutions (10?5 M) under visible light irradiation (? >400 nm). The results show that the prepared nanocomposites have higher absorption and photocatalytic activity than the pristine g-C3N4 and ZnFe2O4 and can be successfully used for water purification from organic azo-dyes.

Blood pressure control predicts plasma matrix metalloproteinase-9 in diabetes mellitus type II.

INTRODUCTION: Matrix metalloproteinase-9 (MMP-9) plays an important role in extracellular and vascular remodelling. We aimed therefore to assess the role of blood pressure (BP) control on plasma MMP-9 in relation to the presence of diabetes mellitus (DM) type II. MATERIAL AND METHODS: Plasma MMP-9 was measured in 61 patients who were divided into two groups depending on their BP control as follows: 49 patients with uncontrolled arterial hypertension (AH) defined as BP values > 130/80 mm Hg and 12 patients with optimal blood pressure values. Plasma MMP-9 levels were measured with immunoassay at discharge. Group comparisons were made with the independent t-test, Mann-Whitney U-test and χ(2) test where appropriate. The associations of the variables with MMP-9 were investigated with linear regression analyses. RESULTS: The diabetics made up 34.4% of the investigated patients. Frequency of DM did not differ between the two BP groups (30.0% vs. 36.6%, p > 0.05). Plasma MMP-9 concentrations differed significantly between the diabetics vs. non-diabetics (median: 1.9 ng/ml, range: 1.0-7.3 vs. 1.4 ng/ml, range: 0.5-4.7, p < 0.05). Stratification across the categories of BP control showed a significant correlation between plasma MMP-9 and DM type II only in the uncontrolled BP group. The significance of that relationship disappeared in the group of patients with optimal BP control. CONCLUSIONS: Plasma values of MMP-9 are raised in patients with DM type II. The results revealed the impact of the combination of uncontrolled AH and DM type II on vascular remodelling processes.

Severe Hypokalemia Masquerading Myocardial Ischemia.

An advanced degree of body potassium deficit may produce striking changes in the electrocardiogram (ECG). These changes can result in incidental findings on the 12-lead ECG or precipitate potentially life-threatening dysrhythmias. Although usually readily recognized, at times these abnormalities may be confused with myocardial ischemia. The object was to report a case of severe hypokalemia mimicking myocardial ischemia. A 33-year-old, previously healthy man, presented to the Emergency Department (ED) with a progressive weakness and chest discomfort. The electrocardiogram showed a marked ST-segment depression in leads II, III, aVF, V1-V6. The initial diagnosis was non ST-elevation myocardial infarction. Echocardiography was normal and troponin levels were within normal limits. A more detailed history revealed that the patient had an episode of acute gastroenteritis with diarrhea and vomiting. Serum chemistries were notable for a potassium concentration of 1,8 mmol per liter. With aggressive electrolyte correction, the ECG abnormalities reverted as potassium levels normalized. Hypokalemia induced ST-segment depression may simulate myocardial ischemia. The differential diagnosis might be difficult, especially in the cases when ST changes are accompanied with chest discomfort.