Chelating water-soluble polymers associated with ultrafiltration membranes for metal ion removal

This article describes the retention properties of commercial chelating water-soluble polymers, for different metal ions in aqueous solution using a liquid-phase polymer-based retention (LPR) technique. The polymers studied were poly(ethyleneimine) or P(EI) (water-free and a 50?% aqueous solution) and poly(ethyleneimine epichlorohydrin) or P(EIE) (a 17?% aqueous solution). These commercial polymers were fractionated by ultrafiltration membranes and then characterized by Fourier-transformed infrared spectroscopy. The extraction process was performed using the following metal ions: Cu²⁺, Cd²⁺, Co²⁺, Ni²⁺, Zn²⁺, Pb²⁺ and Cr³⁺. In the washing studies, we varied the pH (3, 5 and 7) and retention time. The results showed that P(EI) showed high retention for all the metal ions at pH 7 and for selective retention of Cu²⁺ at pH 5, while P(EIE) showed selective retention of Cu²⁺ ions at pH 7. Using the enrichment method, the maximum retention capacity of Cu²⁺ and Cd²⁺ was achieved using a 50?% aqueous solution of P(EI) at pH 5 and 7, respectively. Finally, charge–discharge experiments for Cu²⁺ were analysed by changing the pH from basic to acidic over three cycles. These results showed that it is possible to remove metal ions and regenerate the removal capacity of the polychelatogens using the LPR technique.     

Adsorption of landfill leachates onto activated carbon. Equilibrium and kinetics

The adsorption of stabilized leachates generated in a municipal landfill onto three commercial activated carbons has been investigated. Norit 0.8, Chemviron AQ40 and Picacarb 1240 have been used as adsorbents. Equilibrium experiments have been conducted to obtain the experimental isotherm profiles. Isotherms have been plotted based on the adsorption of general parameters, for instance chemical oxygen demand, total carbon, absorption at 410 nm and absorption at 254 nm. Different literature models and error functions have been used to adequately fit the experimental data. As a rule of thumb, three-parameter models do adjust experimental results better than two-parameter models. Norit 0.8 shows better adsorption characteristics than the rest of activated carbons, both in terms of contaminant level reduction of per unit mass of absorbent and in terms of the process kinetics.     

Characterization of the energy bursts in vibrated shallow granular systems

We study the recently reported energy bursts that take place in a granular system confined to a vertically vibrated shallow box containing two types of grains of equal size but different mass (Rivas in Phys Rev Lett 106:088001?C1?C088001?C4, 2011). In a quasi one dimensional configuration, it is possible to characterize the propagating fronts. The rapid expansion and the subsequent compression of the energy bursts take place at roughly constant velocities. The expansion velocity is 40 times larger than the compression velocity. Starting from an initially segregated configuration it is possible to determine the instants at which the energy bursts begin and the mechanisms that trigger them. Two mechanisms are identified: an oblique collision of a heavy grain with a light one in contact with one of the horizontal walls and a slow destabilization produced by light grains that are surrounded by heavy ones.     

Synthesis and characterization of new water‐soluble metal–polymer complex and its application for arsenite retention

New water‐soluble metal–polymers of poly(acrylic acid)s (AA) with different amounts of tin (3, 5, 10, and 20 wt %) were synthesized and characterized. The materials were characterized by ¹H NMR and FTIR spectroscopy, X‐ray diffraction (XRD), specific area by isotherm of CO₂, and thermogravimetry‐differential scanning calorimetry (TG‐DSC). The synthesized material is crystalline and shows an average crystal size 90–130 nm and has a high thermal stability (>200°C). Texturally, they are complexes of small specific area, which decreases when the crystal size increases with the tin content. Presumably, the Sn(II) ions coordinate through 2‐4 carboxylate groups by a conventionally bidentate structure; however, they are not symmetric. Studies have been dedicated to support of tin in polymers to increase its efficiency in eliminating pollutants. The tin‐metal salt is added to the poly(AA) matrix to increase its ability to remove As(III) from an aqueous solution. The liquid‐phase polymer‐based retention technique is applied to retain and separate contaminants from water. The analysis of As(III) and As(V) species was made by combining liquid high‐resolution chromatographic coupled to hydride generation absorption atomic spectrophotometer (HPLC‐HG‐AAS). All indicated that As(III) was the predominant species bound to the polymer complex for the pH range 4–8. The polymers containing 10 and 20 wt % Sn presented the highest retention of 70 and 90% As(III), respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Expression and regulation of mitochondrial uncoupling protein 1 from brown adipose tissue in Leishmania major promastigotes

Changes in the oligosaccharides attached to glycoproteins and glycolipids have been observed in a variety of malignancies. To understand the relationship between oligosaccharide expression and breast cancer progression we extracted and mapped the sialylated and neutral oligosaccharides from primary breast tumours of patients treated between 1979 and 1981 at Middlesex and University College Hospitals, London. Tumours from two patient groups were evaluated as short-term and long-term survivors. Short-term survivors developed widespread disease within five years (n = 10) whereas long-term survivors had no sign of cancer after fifteen years (n = 9). Paraffin-wax embedded breast cancer specimens were microdissected, the oligosaccharides were released and mapped by separation on anion-exchange and gel permeation chromatography columns. A decrease in the diversity of sialylated and neutral oligosaccharides and the number of sialylated structures was observed in aggressive breast cancers. Aggressive cancers had elevated levels of a mono- and tri-sialylated oligosaccharide only found in trace levels in non-aggressive cancers.     

Interdisciplinary question generation: Synthesis and validity analysis of the 1993–1997 bovine mastitis-related literature

Interdisciplinary synthesis and validity analysis (ISVA), a structured learning approach which integrates learning and communication theories, meta-analytic evaluation methods, and literature management-related technologies was applied in the context of the 1993–1997 bovine mastitis research literature. This study investigated whether ISVA could: 1) facilitate the analysis and synthesis of interdisciplinary knowledge claims, and 2) generate projects or research questions. The bovine mastitis-related literature was conceptualized as composed of microbiological, immunological, and epidemiological dimensions. Keywords involving these dimensions were searched in theMedline andAgricola databases. A final list of 148 articles were retrieved, analyzed, synthesized into fifteen information sub-sets, and evaluated for construct, internal, external and statistical validity through an interdisciplinary iterative dialogical process. Validity threats were re-phrased as new research or educational projects.     

Verrucous carcinoma of the penis

Thirty-four patients with osteoarthritis (OA) and 32 patients with rheumatoid arthritis (RA) were studied to determine the effects of OA and RA on the laxity of the knee joints. Laxity was measured with the Genucom Knee Analysis System. The antero-posterior laxity of the OA and RA knees was greater than the control, normal knees in the early stage, and decreased with the severity of disease in OA, but not in RA. Severe OA and RA were associated with a restricted internal-external rotation at the knee joint compared with the control. Internal-external rotation decreased with worsening of both diseases. Varus-valgus laxity tended to increase slightly with the severity of disease. While the morphological changes of the cruciate ligaments in advanced OA and RA were not statistically different, the laxity of OA-afflicted knees was affected slightly by the severity of the damage to the cruciate ligaments.