Determination of Valence States of Chromium in Calcium Chromates by Using X-ray Absorption Near-Edge Structure (XANES) Spectroscopy

Calcium chromates with the empirical formulas Ca₁₀Cr₆−O₂₅, Ca₃Cr₂O₈, and Ca₅Cr₃O₁₂, which form at temperatures >900°C at CaO:Cr₂O₃ molar ratios of 3 in an oxidation atmosphere have been synthesized in the pure state. X-ray absorption near-edge structure (XANES) spectroscopy has been used to determine the average valence state of chromium in the samples. The presence of unusual chromium valence states, 4+ and 5+, which was proposed via X-ray diffractometry studies, is strongly supported.     

Removal of Copper from Aqueous Solutions with Zeolites and Possible Treatment of Exhaust Materials

The mechanism of Cu²⁺ loading into commercially available natural HEU-type and synthetic LTA-type zeolites for their possible use in environmental processes, such as water and air treatment applications, was studied. Elemental analysis, SEM/EDXS, XRD, XAS and XPS analyses revealed 4-fold coordination of Cu²⁺ cations with oxygen atoms in the pores, a predominant location of copper atoms on the surface of crystallites and retained crystallinity of zeolites throughout the processes. The post-treatment of Cu²⁺-loaded samples with HCl and/or NaCl solutions confirmed the predominantly reversible sorption of copper on zeolites from aqueous solutions by ion-exchange mechanism and, therefore, excellent regeneration possibilities for both types of zeolites. Furthermore, with the calcination of exhaust metal-loaded zeolites, catalysts for total toluene oxidation reaction, as a model VOC pollutant, were obtained.     

Physicochemical Studies and Anticancer Potency of Ruthenium η-p-Cymene Complexes Containing Antibacterial Quinolones

With the aim of exploring the anticancer properties of organometallic compounds with bioactive ligands, Ru(arene) compounds of the antibacterial quinolones nalidixic acid (2) and cinoxacin (3) were synthesized, and their physicochemical properties were compared to those of chlorido(η(6)-p-cymene)(ofloxacinato-κ(2)O,O)ruthenium(II) (1). All compounds undergo a rapid ligand exchange reaction from chlorido to aqua species. 2 and 3 are significantly more stable than 1 and undergo minor conversion to an unreactive [(cym)Ru(μ-OH)(3)Ru(cym)](+) species (cym = η(6)-p-cymene). In the presence of human serum albumin 1-3 form adducts with this transport protein within 20 min of incubation. With guanosine 5'-monophosphate (5'-GMP; as a simple model for reactions with DNA) very rapid reactions yielding adducts via its N7 atom were observed, illustrating that DNA is a possible target for this compound class. A moderate capacity of inhibiting tumor cell proliferation in vitro was observed for 1 in CH1 ovarian cancer cells, whereas 2 and 3 turned out to be inactive.     

Effects of EPDM and wollastonite on structure of isotactic polypropylene blends and composites

Polypropylene blends and composites with 5, 10, and 15 vol % of EPDM and 2, 4, and 6 vol % of untreated and treated wollastonite filler were examined by applying different techniques. Elastomeric ethylene/propylene/diene terpolymer (EPDM) component and wollastonite influenced the crystallization process of isotactic polypropylene (iPP) matrix in different ways. The nucleation of hexagonal β‐iPP, the increase of overall degree of crystallinity, and crystallite size of iPP were more strongly affected by wollastonite than the addition of EPDM was. Both ingredients also differently influenced the orientation of α‐form crystals in iPP matrix. Wollastonite increased the number of a*‐axis‐oriented α‐iPP lamellae plan parallel to the sample surface, whereas the addition of EPDM reoriented the lamellae. The orientation parameters of ternary composites exhibited intermediate values between those for binary systems because of the effects of both components. EPDM elastomer considerably affected well‐developed spherulitization of iPP, increasing the spherulite size. Contrary to EPDM, because of nucleating ability or crystal habit, wollastonite caused significantly smaller iPP spherulites. Small spherulites in ternary iPP/EPDM/wollastonite composites indicated that the wollastonite filler (even in smallest amounts) exclusively determined the morphology of ternary composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4072–4081, 2004     

Wollastonite-reinforced polypropylene composites modified with novel metallocene EPR copolymers. I. Phase structure and morphology

Supermolecular structure of isotactic polypropylene/wollastonite/metallocene propylene–ethylene copolymers (iPP/W/EPR) composites was studied as a function of elastomer content (from 0 to 20 vol%) by optical, scanning, and transmission electron microscopy, wide-angle X-ray diffraction, and differential scanning calorimetry. Both, wollastonite and dispersed EPR particles, homogeneously incorporated into the iPP matrix, and affected the final phase structure and morphology of the iPP/wollastonite/EPR composites. Wollastonite particles were orientated plane-parallel to the sample surface and hindered spherulite growth of the iPP matrix. EPRs enhanced plane-parallel orientation of wollastonite and simultaneously enhanced the spherulite and crystallite growth in the iPP matrix during the solidification of polymer melt. Ternary iPP/wollastonite/EPR composites exhibited significant prevalence of separated microphase morphology (over core-shell morphology) because of constitution similarity of P-E and iPP chains. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers.     

Centrifugal impact milling of resins

Investigation of phenol formaldehyde resins milling in centrifugal impact mills is presented. The particle size distribution, energy consumption and size reduction ratio were observed at different material loads, grinding rotor velocities and air flow rates. Experimentally measured data were modelled using previously developed Rosin–Rammler formula and two parameters; the mean particle size and the width of distribution were calculated for different operating conditions. Optimal process conditions and scale up calculation for three different sized mills are proposed. The results may contribute to better understanding of milling processes in industrial plants, with respect to operation costs, energy consumption and environmental care.     

Effect of Nucleation Cavities on Enhanced Boiling Heat Transfer in Microchannels

Boiling instabilities, high temperatures of the onset of boiling (ONB), and early transition to dryout are some of the insufficiently resolved issues of flow boiling in microchannels. This article addresses the flow boiling challenges with the incorporation of flow restrictors to reduce the boiling instabilities and hinder vapor backflows. In addition, the temperature of the ONB was lowered and the heat transfer coefficient was increased during boiling with the fabrication of potential nucleation cavities in the microchannel walls and bottom. Experiments were conducted with degassed double-distilled water in arrays of microchannels with the hydraulic diameter ranging from 25 to 80 µm, whereas the nucleation cavities characteristic sizes varied from 2 to 12 µm. The temperatures of the ONB were up to 35 K lower in the microchannel array with properly sized nucleation cavities compared to arrays of microchannels, in which the etched nucleation cavities were less suitable. The combined effect of fabricated nucleation cavities and interconnected microchannels increased the heat transfer coefficient from three to 10 times depending on the size of the etched nucleation cavities and the transferred heat flux in the microchannel arrays.     

Prediction of Chronic Inflammation for Inhaled Particles: the Impact of Material Cycling and Quarantining in the Lung Epithelium

On a daily basis, people are exposed to a multitude of health-hazardous airborne particulate matter with notable deposition in the fragile alveolar region of the lungs. Hence, there is a great need for identification and prediction of material-associated diseases, currently hindered due to the lack of in-depth understanding of causal relationships, in particular between acute exposures and chronic symptoms. By applying advanced microscopies and omics to in vitro and in vivo systems, together with in silico molecular modeling, it is determined herein that the long-lasting response to a single exposure can originate from the interplay between the newly discovered nanomaterial quarantining and nanomaterial cycling between different lung cell types. This new insight finally allows prediction of the spectrum of lung inflammation associated with materials of interest using only in vitro measurements and in silico modeling, potentially relating outcomes to material properties for a large number of materials, and thus boosting safe-by-design-based material development. Because of its profound implications for animal-free predictive toxicology, this work paves the way to a more efficient and hazard-free introduction of numerous new advanced materials into our lives.     

Manganese Functionalized Silicate Nanoparticles as a Fenton‐Type Catalyst for Water Purification by Advanced Oxidation Processes (AOP)

Wet hydrogen peroxide catalytic oxidation (WHPCO) is one of the most important industrially applicable advanced oxidation processes (AOPs) for the decomposition of organic pollutants in water. It is demonstrated that manganese functionalized silicate nanoparticles with interparticle porosity act as a superior Fenton‐type nanocatalyst in WHPCO as they can decompose 80% of a test organic compound in 30 minutes at neutral pH and room temperature. By using X‐ray absorption spectroscopic techniques it is also shown that the superior activity of the nanocatalyst can be attributed uniquely to framework manganese, which decomposes H₂O₂ to reactive hydroxyls and, unlike manganese in Mn₃O₄ or Mn₂O₃ nanoparticles, does not promote the simultaneous decomposition of hydrogen peroxide. The presented material thus introduces a new family of Fenton nanocatalysts, which are environmentally friendly, cost‐effective, and possess superior efficiency for the decomposition of H₂O₂ to reactive hydroxyls (AOP), which in turn readily decompose organic pollutants dissolved in water.