Use of a Mixture of Polyols Based on Metasilicic Acid and Recycled PLA for Synthesis of Rigid Polyurethane Foams Susceptible to Biodegradation

Two polyol raw materials were obtained in the conducted research, one based on metasilicic acid (MSA), the other based on poly(lactic acid) (PLA) waste. The obtained polyols were characterized in terms of their applicability for the production of rigid polyurethane foams (RPUFs). Their basic analytical properties (hydroxyl number, acid number, elemental analysis) and physicochemical properties (density, viscosity) were determined. The assumed chemical structure of the obtained new compounds was confirmed by performing FTIR and ¹H NMR spectroscopic tests. Formulations for the synthesis of RPUFs were developed on the basis of the obtained research results. A mixture of polyols based on MSA and PLA in a weight ratio of 1:1 was used as the polyol component in the polyurethane formulation. The reference foam in these tests was a foam that was synthesized only on the basis of MSA-polyol. The obtained RPUFs were tested for basic functional properties (apparent density, compressive strength, water absorption, thermal conductivity coefficient etc.). Susceptibility to biodegradation in soil environment was also tested. It was found that the use of mixture of polyols based on MSA and PLA positively affected the properties of the obtained foam. The polyurethane foam based on this polyol mixture showed good thermal resistance and significantly reduced flammability in comparison with the foam based MSA-polyol. Moreover, it showed higher compressive strength, lower thermal conductivity and biodegradability in soil. The results of the conducted tests confirmed that the new foam was characterized by very good performance properties. In addition, this research provides information on new waste management opportunities and fits into the doctrine of sustainable resource management offered by the circular economy.     

Annexins A2, A6 and Fetuin-A Affect the Process of Mineralization in Vesicles Derived from Human Osteoblastic hFOB 1.19 and Osteosarcoma Saos-2 Cells

The mineralization process is initiated by osteoblasts and chondrocytes during intramembranous and endochondral ossifications, respectively. Both types of cells release matrix vesicles (MVs), which accumulate P_i and Ca²⁺ and form apatites in their lumen. Tissue non-specific alkaline phosphatase (TNAP), a mineralization marker, is highly enriched in MVs, in which it removes inorganic pyrophosphate (PP_i), an inhibitor of apatite formation. MVs then bud from the microvilli of mature osteoblasts or hypertrophic chondrocytes and, thanks to the action of the acto-myosin cortex, become released to the extracellular matrix (ECM), where they bind to collagen fibers and propagate mineral growth. In this report, we compared the mineralization ability of human fetal osteoblastic cell line (hFOB 1.19 cells) with that of osteosarcoma cell line (Saos-2 cells). Both types of cells were able to mineralize in an osteogenic medium containing ascorbic acid and beta glycerophosphate. The composition of calcium and phosphate compounds in cytoplasmic vesicles was distinct from that in extracellular vesicles (mostly MVs) released after collagenase-digestion. Apatites were identified only in MVs derived from Saos-2 cells, while MVs from hFOB 1.19 cells contained amorphous calcium phosphate complexes. In addition, AnxA6 and AnxA2 (nucleators of mineralization) increased mineralization in the sub-membrane region in strongly mineralizing Saos-2 osteosarcoma, where they co-localized with TNAP, whereas in less mineralizing hFOB 1.19 osteoblasts, AnxA6, and AnxA2 co-localizations with TNAP were less visible in the membrane. We also observed a reduction in the level of fetuin-A (FetuA), an inhibitor of mineralization in ECM, following treatment with TNAP and Ca channels inhibitors, especially in osteosarcoma cells. Moreover, a fraction of FetuA was translocated from the cytoplasm towards the plasma membrane during the stimulation of Saos-2 cells, while this displacement was less pronounced in stimulated hFOB 19 cells. In summary, osteosarcoma Saos-2 cells had a better ability to mineralize than osteoblastic hFOB 1.19 cells. The formation of apatites was observed in Saos-2 cells, while only complexes of calcium and phosphate were identified in hFOB 1.19 cells. This was also evidenced by a more pronounced accumulation of AnxA2, AnxA6, FetuA in the plasma membrane, where they were partly co-localized with TNAP in Saos-2 cells, in comparison to hFOB 1.19 cells. This suggests that both activators (AnxA2, AnxA6) and inhibitors (FetuA) of mineralization were recruited to the membrane and co-localized with TNAP to take part in the process of mineralization.     

Removal of boron from aqueous solution by composite chitosan beads

Various metal-oxide nanoparticles and chitosan were blended to form new adsorbents (M-Oxide-CTS) for removing boron from aqueous solutions in a batch system. The maximum boron adsorption capacity (q = 7.8 mg/g) was reached at pH = 4 within 5 min. Calculations based on Langmuir, Freundlich, and Dubinin–Radushkevich models showed the heterogeneous and physical nature of boron adsorption on M-Oxide-CTS. Modeling of the thermodynamic date indicated the nonspontaneous and exothermic process. The pseudo-second-order model adequately described the boron adsorption on M-Oxide-CTS. Desorption by means of alkaline solution at pH = 12 was carried out successfully.     

Gaussian mixture decomposition in the analysis of MALDI‐TOF spectra

The article presents a method of protein matrix‐assisted laser desorption and ionization‐time of flight (TOF) spectra analysis. The method performs peaks detection. Spectra are analysed with Gaussian mixture decomposition. The results obtained are used for peaks identification purposes. The concept of the method is that a single peak is represented by one Gaussian distribution. The expectation‐maximization algorithm and maximum likelihood rule are used for spectra processing. The analysis can be done for a set of spectra with use of the mean spectrum, or it may be performed for a single spectrum at a time. The number of mixture‐model components is estimated by the Bayesian information criterion. Before the main analysis, a few pre‐processing steps need to be done. Spectra should be subjected to calibration, normalization, denoising, baseline correction, etc. The aim of the work is to identify peptides in the analysed sample on the basis of the parameters of the mixture model and to find differences between spectra in the analysed set.     

Calixarene-based extractants for heavy metal ions removal from aqueous solutions

The article reviews the literature on the possibility of application of the calixarene-based compounds for selective separation of toxic heavy metals from aqueous solutions by the solvent extraction and transport across liquid membranes. The specific three-dimensional structure of calixarenes and their derivatives, simple and low-cost synthesis, and ease of chemical transformation qualify these compounds for the role of selective chemical extractants of toxic heavy metal ions present in industrial wastewater. This article analyses the influence of various process factors, with the greatest emphasis on the structure of the extractants/carriers, on efficient separation of heavy metal ions, primarily those most commonly found in galvanic wastewater.     

Microstructural Control of Colloidal‐Based Ceramics by Directional Solidification Under Weak Magnetic Fields

The use of weak magnetic fields to control the microstructural evolution of colloidal‐based systems in conjunction with directional solidification is demonstrated as a convenient processing route to fabricate anisotropic ceramic scaffolds with complex microarchitectures. A variety of graded and aligned microstructures were formed by applying external static magnetic fields oriented radially, axially, and transversely with respect to the solidification direction of freezing slurries containing micro/nanoparticles of ZrO₂ and Fe₃O₄. The graded structures, formed by the radial and axial fields, resemble core–shell architectures composed of dense outer perimeters surrounding porous inner cores. The aligned structures, formed by transverse fields, exhibit two modes of microstructural alignment: lamellar walls aligned by the growing ice crystals and mineral bridges aligned by the magnetic fields. The alignment of mineral bridges that connect adjacent lamellae, provide these scaffolds enhanced strength and stiffness when compressed parallel to their orientation (parallel to the direction of the magnetic field).     

Preparation and characterization of polysiloxane networks containing metallic platinum particles

Polysiloxane networks obtained via cross‐linking of D₄/V₄ polysiloxane served as matrices for incorporation of metallic Pt particles. D₄/V₄ polymer used in the crosslinking was synthesized by equilibrium cationic ring‐opening polymerization of the corresponding cyclotetrasiloxane monomers. Linear (^HMM^H) or cyclic ( ) hydrosiloxanes, at different hydrosiloxane to D₄/V₄ molar ratios, were applied as crosslinking agents. Platinum species were introduced into the crosslinked products from PtCl₄ solution in THF or in isopropyl alcohol via the reduction of Pt⁴⁺ to Pt⁰ in the presence of active Si‐H sites. Various analytical techniques: UV‐vis and FTIR spectroscopy, swelling measurements, XRD, SEM, and thermogravimetric analysis were applied to control the progress of the reaction or to characterize the intermediate or final products. IR spectroscopy allowed to determine the efficiency of cross‐linking process and to investigate the consumption of un‐reacted Si‐H groups accompanying the reduction of platinum ions. XRD studies confirmed the incorporation of metallic platinum into all systems. Good thermal stability of obtained products was found using thermogravimetric analysis. According to SEM investigations, the applied network as well as the solvent used in the reduction process influenced the dispersion of metallic particles on the surface of the matrices. The obtained Pt‐systems exhibited mainly redox activity in catalytic isopropyl alcohol conversion used as a test reaction. Significant differences in catalytic properties between systems containing different matrices were observed. The promoting effect on the catalytic activity was found in the case of C‐P type support, i.e. the polysiloxane network obtained using the cyclic hydrosiloxane as the crosslinking agent. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43096.     

Fishing along the Clinch River arm of Watts Bar reservoir adjacent to the Oak Ridge Reservation,Tennessee: behavior,knowledge and risk perception

Catching and eating fish is usually viewed as a fun, healthy and safe activity. However, with continuing increases in fish consumption advisories due to the contamination of our environment, anglers have to decide whether or not to eat the fish they catch. The Clinch River arm of Watts Bar Reservoir is under a fish consumption advisory because of elevated PCB concentrations in striped bass (Morone saxatilis), catfish (Ictalurus spp.) and sauger (Stizostedion canadense) due in part from contaminants released from the US Department of Energy's (USDOE's) Oak Ridge Reservation (ORR) in East Tennessee. To obtain information about the demographics, fishing behavior, knowledge, fish consumption and risk perception of anglers, a survey was conducted of 202 people actively fishing either on land or by boat along the Clinch River arm of Watts Bar Reservoir adjacent to the ORR from Melton Hill Dam to the Poplar Creek confluence or on Poplar Creek within ORR boundaries from mid-March to early November 2001. Even though 81% of people interviewed knew about the fish consumption advisories for the study area, 48% of them thought the fish were safe to eat, while 38% ate the fish that they caught from the study area. Approximately 36% of anglers who had knowledge of the fish consumption warnings ate fish from the study area. Providing confirmation that people fish for many reasons, 35% of anglers interviewed did not eat fish at all. The majority of anglers interviewed knew about the fish consumption advisories because of the signs posted throughout the study area. However, few people knew the correct fish advisories. Significantly fewer blacks had knowledge of the fish consumption warnings than whites. Information resulting from this study could be used to design a program with the objective of reaching the people who may be most at risk from eating fish caught from the Clinch River arm of Watts Bar Reservoir.     

Spatial and temporal patterns in metal levels in eggs of common terns (Sterna hirundo) in New Jersey

Seabirds are excellent subjects for examination of metals because they feed at different trophic levels, including as top-level piscivores, they are long-lived, and many are abundant and widely distributed. In this paper we examine the levels of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in eggs from common terns (Sterna hirundo) nesting on five saltmarsh islands in Barnegat Bay, New Jersey from 2000 to 2002. We test the null hypothesis that there were no locational or temporal differences from 2000 to 2002. There were significant locational differences in all metals in some years, although the differences were not large. The levels of most metals do not seem sufficiently high to cause adverse effects, although the levels of mercury in eggs of some common terns from the bay are within the range known to cause adverse effects. Mercury in common tern eggs may be a contributing cause to their local decline.