Naproxen removal from water by chlorination and biofilm processes

Naproxen is an anti-inflammatory pharmaceutical that has been detected in natural and engineered aquatic environments. The primary aim of this research was to study chemical transformations of naproxen following chlorine oxidation, which is common in water and wastewater treatment systems. Synthetic waters containing elevated concentrations of naproxen were oxidized by free chlorine at naproxen:chlorine molar ratios of 0.02-3:1 and pH values of 5-9. The formation of naproxen products was dependent on pH, chlorine dosage and contact time. This study demonstrates that naproxen readily reacts with free chlorine and forms disinfection products. The formation of specific reaction products can vary depending on the characteristics of the water or wastewater and treatment operating conditions. More research is needed to identify intermediate and chemical reaction end products and to understand the reaction kinetics of naproxen chlorination for a range of water and wastewater treatment conditions. A secondary aim of this research was to study effects of naproxen and its chlorination products on biofilm processes, which are common in water and wastewater treatment systems and natural aquatic environments. A bioreactor was fed a naproxen solution and then fed a solution at the same naproxen concentration following contact with free chlorine. Results indicate that naproxen was not degraded biologically for the conditions of this study. In contrast, the naproxen solution containing products of chlorination caused an adverse response by discharging biomass from the bioreactor. Results therefore demonstrate that naproxen products of chlorination can adversely affect a biofilm process, which potentially can impact the performance of biofilm processes in natural and engineered aquatic environments. More research is needed to study naproxen chlorination reactions at low concentrations and in complex matrices, and to understand the toxicological relevance of naproxen and its products of chlorination in natural and engineered aquatic environments.     

Increase of the final setting time of brushite cements by using chondroitin 4-sulfate and silica gel

Chondroitin 4-sulfate (C4S) is a bioactive glycosaminoglycan with inductive properties in bone and tissue regeneration. Dicalcium phosphate dehydrate cements (known as brushite) are biocompatible and resorbable materials used in bone and dental surgery. In this study we analyzed the effect of C4S on the setting of a calcium phosphate cement and the properties of the resulting material. Brushite based cement powder was synthesised by mixing monocalcium phosphate with β-tricalcium phosphate and sodium pyrophosphate. When the concentration of C4S, in the liquid added to the cement powder, was between 1 and 8% the cement final setting time increases. Furthermore, the cement diametral tensile strength remains unaffected when solutions with concentrations of C4S below 5% were used, but decreases at higher C4S concentrations. Calorimetric analysis showed that the cements prepared with C4S alone and in combination with silica gel have a greater content of hydrated water. We concluded from our study that the addition of small amounts of C4S increases the cement setting time without affecting its diametral tensile strength and at the same time improves the cement’s hydrophilicity.     

The Drying of Pyridine Hydrobromide

1 INTRODUCTIONThe drying of fine chemicals and pharmaceuticals is dominated by a number of special factorscompared to the drying of bulk chemicals.These include:very high value of product;lowthroughputs(typically,100 kg·h~(-1));materials that frequently possess toxic properties andare often sticky,pasty and difficult to handle when wet;the moisture to be evaporated ofteninvolves solvents;and multipurpose processing plants.     

Effect of processing on water absorption and softening kinetics in chickpea (Cicer arietinumL) seeds

The processing effect on the physical properties of chickpea seeds (kabuli type cv Athenas) is reported. Soaking of chickpea seeds in different solutions (distilled water, 0·5% NaHCO₃ and 0·5% CaCl₂) is characterised by a rapid water absorption followed by a decrease in the hydration rate to saturation point. An improvement in chickpea softening rate and water absorption during cooking, with previous 12 h soaking in 0·5% NaHCO₃, was observed. The presence of Ca²⁺ ions delayed the softening process in chickpea seeds. Physicochemical changes associated to the soaking and cooking process necessary for reducing cooking time are discussed. The texturometer method was estimated as a suitable objective method for the evaluation of the cooking degree in chickpea seeds. © 1998 Society of Chemical Industry     

Study of the effect of the monomer pressure on the copolymerization of ethylene with 1-hexene

The effect of ethylene pressure on the copolymerization of ethylene with 1-hexene was studied. The results show an increasing of productivities (g of polymer/n_Zr h) with pressure. This tendency was not observed for the activity (g of polymer/n_Zr h bar) that decreases when pressure is raised. When varing the pressure, the characteristics and properties of the formed copolymers are in accordance with the expectation for changes in the monomer concentration; increasing the pressure causes a decrease in comonomer incorporation. At higher ethylene pressure, the polymer is more crystalline due to less incorporation of 1-hexene and the molecular weight is higher. The density of the copolymers also decreases with comonomer incorporation into the copolymer © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2567–2574, 1997     

Corrosion Behaviour of Type 316L Stainless Steel in Hot Caustic Aqueous Environments

Metals and Materials International - The corrosion behaviour of type 316L stainless steel in aqueous 30–50 wt%. NaOH at temperatures up to 90 °C has been elucidated....     

Antioxidant activity of Carob fruit extracts in cooked pork meat systems during chilled and frozen storage

The purpose of this study was to evaluate the effect of adding condensed tannins in the form of non-purified (Liposterine^®) or purified (Exxenterol^®) extracts obtained from Carob fruit to prevent lipid cooked pork meat systems from oxidising during chilling and frozen storage. The antioxidant activity of these extracts was compared with that of α-tocopherol. Meat lipid alteration was evaluated as thiobarbituric acid reactive substances content (TBARS) and polar material-related triglyceride compounds followed by high-performance size-exclusion chromatography (HPSEC). TBARS levels were lower (P < 0.05) in samples containing Liposterine (LM), Exxenterol (EM), and α-tocopherol (TM) than in control sample (CM) under chilled storage. TBARS formation was similar (P > 0.05) for LM and EM but lower (P < 0.05) than for TM. Polar material increased several times in all samples, but significantly less in TM and EM than in LM. Thermal oxidation compounds determined by HPSEC were lower (P < 0.05) in EM than in LM or TM. The changes in polar material were proportionally smaller after six months frozen storage than after chilled storage, with Exxenterol displaying the highest antioxidant protection. Therefore Carob fruit extracts can be successfully used to reduce fat alteration in cooked pork meat at chilled and frozen temperatures.     

Kidney-Protector Lipidic Cilastatin Derivatives as Structure-Directing Agents for the Synthesis of Mesoporous Silica Nanoparticles for Drug Delivery

Mesoporous silica nanomaterials have emerged as promising vehicles in controlled drug delivery systems due to their ability to selectively transport, protect, and release pharmaceuticals in a controlled and sustained manner. One drawback of these drug delivery systems is their preparation procedure that usually requires several steps including the removal of the structure-directing agent (surfactant) and the later loading of the drug into the porous structure. Herein, we describe the preparation of mesoporous silica nanoparticles, as drug delivery systems from structure-directing agents based on the kidney-protector drug cilastatin in a simple, fast, and one-step process. The concept of drug-structure-directing agent (DSDA) allows the use of lipidic derivatives of cilastatin to direct the successful formation of mesoporous silica nanoparticles (MSNs). The inherent pharmacological activity of the surfactant DSDA cilastatin-based template permits that the MSNs can be directly employed as drug delivery nanocarriers, without the need of extra steps. MSNs thus synthesized have shown good sphericity and remarkable textural properties. The size of the nanoparticles can be adjusted by simply selecting the stirring speed, time, and aging temperature during the synthesis procedure. Moreover, the release experiments performed on these materials afforded a slow and sustained drug release over several days, which illustrates the MSNs potential utility as drug delivery system for the cilastatin cargo kidney protector. While most nanotechnology strategies focused on combating the different illnesses this methodology emphasizes on reducing the kidney toxicity associated to cancer chemotherapy.     

Adsorption of Me(II), HEDP, and Me(II)-HEDP onto boehmite at nonstoichiometric Me(II)-HEDP concentrations

In aqueous environments, certain heavy metals are toxic even at very low concentrations. The main pathway of metal removal in the aquatic systems is via adsorption onto surfaces. These are desired processes that help decrease the dissolved fraction of metals in natural water. The presence of organic ligands as mono- and polyphosphonates may produce drastic changes in the mobility of the heavy metals. 1-Hydroxyethane-(1,1-diphosphonic acid) (HEDP) is a very strong chelating agent widely used in industrial applications. This study examines the effect of HEDP on the adsorption of Cu(II), Zn(II), and Cd(II) onto boehmite in nonstoichiometric conditions, with the HEDP concentration higher than the corresponding Me(II) cations. At high surface loading and low pH, HEDP removes Zn(II) and Cd(II) from solution to an appreciable extent. The data are modeled assuming an anionic-ternary complex formation. In the same conditions, Cu(II) adsorption is significantly suppressed at intermediate values of pH, and this behavior is linked to Cu-HEDP complex formation in solution. At low surface covering, the effects of HEDP on metal adsorption are either negligible or slight. This behavior suggests that both ligand and metal are mainly adsorbed in separate form. All experimental data indicate that no changes are observed in the pH edges for phosphonate adsorption. The surface constants to fit the experimental data were calculated by applying the 2-K model constant capacitance (CCM).     

Cloning and sequencing of the histidine decarboxylase gene from Photobacterium phosphoreum and its functional expression in Escherichia coli

The major causative agent of scombroid poisoning is histamine formed by bacterial decarboxylation of histidine. We reported previously that histamine was exclusively formed by the psychrotrophic halophilic bacteria Photobacterium phosphoreum in scombroid fish during storage at or below 10 degrees C. Moreover, histamine-forming ability was affected by two histidine decarboxylases (HDCs): constitutive and inducible enzymes. In this study, the gene encoding P. phosphoreum HDC was cloned into Escherichia coli and sequenced. A sequence analysis of the DNA corresponding to the hdc gene revealed an open reading frame of 1,140 bp coding for a pyridoxal-5'-phosphate-dependent HDC of 380 amino acid residues with a predicted molecular mass of 42.6 kDa. The HDC amino acid sequences formed a phylogenetic clade with strong bootstrap support and revealed high sequence similarities among the P. phosphoreum isolate and species of the family Enterobacteriaceae and a separate phylogenetic branch with the lowest sequence similarity between the isolate and the taxonomically closer Listonella anguillarum. The T7 promoter was used to overexpress the hdc gene in E. coli cells. The recombinant clone, E. coli BL21(DE3), displayed significant levels of HDC activity. The recombinant hdc gene was suggested to code the inducible HDC; therefore, the optimum reaction conditions of the recombinant HDC were similar to those of the inducible HDC in the P. phosphoreum isolate. In addition, a putative catabolite-repressor protein binding site, amino acid permease gene, and histidine-tRNA synthetase gene were found in flanking regions of the hdc gene.