Effects of Nisin and Lysozyme on Growth Inhibition and Biofilm Formation Capacity of Staphylococcus aureus Strains Isolated from Raw Milk and Cheese Samples

Effects of nisin and lysozyme on growth inhibition and biofilm formation capacity of 25 Staphylococcus aureus strains isolated from raw milk (13 strains) and cheese (12 strains) were studied. Nisin was tested at concentrations between 0.5 and 25 μg/ml; the growth of all strains was inhibited at 25 μg/ml, but the resistances of strains showed a great variation at lower nisin concentrations. In contrast, lysozyme tested at concentrations up to 5.0 mg/ml showed no inhibition on the growth of strains. Nisin used at the growth inhibitory concentration prevented the biofilm formation of strains, but strains continued biofilm formation at subinhibitory nisin concentrations. Lysozyme did not affect the biofilm formation of 19 of the strains, but it caused a considerable activation in the biofilm formation capacity of six strains. Twelve of the strains contained both biofilm-related protease genes (sspA, sspB, and aur) and active proteases; eight of these strains were nisin resistant. These results suggest a potential risk of S. aureus growth and biofilm formation when lysozyme is used in the biopreservation of dairy products. Nisin can be used to control growth and biofilm formation of foodborne S. aureus, unless resistance against this biopreservative develops.     

Treatment of Jewelry Manufacturing Effluent Containing Cyanide Using Ozone-Based Photochemical Advanced Oxidation Processes

This article considers Advanced Oxidation Processes involving O₃, O₃/UV, O₃/H₂O₂/UV, and H₂O₂/UV to destroy cyanide in jewelry manufacturing wastewaters. All experiments were performed in a semibatch reactor. The results showed that total cyanide can be reduced with different reaction rates, and the decrease of total cyanide can be described by pseudo–first-order kinetics. The reaction was performed under different pH values and H₂O₂ dosages to find the optimal conditions for the oxidation processes. The ozonation process destroyed total cyanide faster at a pH = 12, whereas ozonation combined with H₂O₂ and/or UV destroyed cyanide faster at a pH =10. The total cyanide destruction rate in the UV/H₂O₂ (700 mg/L) treatment was the highest among all studied processes, with removal efficiencies of 99% for CN^?, 99% for COD and 99% for TOC.     

PolyHIPE/pullulan composites derived from glycidyl methacrylate and 1,3‐butanediol dimethacrylate‐based high internal phase emulsions

Highly porous composites of poly(glycidyl methacrylate‐co‐1,3‐butanediol dimethacrylate) and pullulan were prepared as semi‐interpenetrating polymer networks by cross‐linking of high internal phase emulsions (HIPEs). HIPEs were prepared by using an aqueous phase made of pullulan dissolved in deionised water. Instead of conventional cross‐linkers such as divinyl benzene, 1,3‐butanediol dimethacrylate was used as a flexible co‐monomer. Morphological and mechanical properties of the porous composites with an initial pullulan loading ranging from 1 to 10 wt % have been investigated. Resulting composites were tested in terms of uniaxial compression stress and it was found out that the use of pullulan and flexible co‐monomer in the HIPE preparation increases the compression modulus from 13.53 to 30.8 MPa. Textural analyses of the resulting composites show that in all cases open cellular foams composed of primary cavities (～112–74 μm) connected with secondary interconnected pores were produced with a specific surface area in the range of 1.7–3.0 m² g^?1. In addition, the influence of using porogen in the oil phase was investigated. It was found that using a porogen reduces the cavity size diameter from ～112 to 20 µm and increases the compression modulus from 13.53 to 47.06 MPa. POLYM. ENG. SCI., 55:2636–2642, 2015. © 2015 Society of Plastics Engineers     

Color stability of bulk‐fill composites immersed in different drinks

Bulk‐fill composites show structural differences compared to those of conventional resin composites. Their more reactive photoinitiators, monomer compositions, and increased filler content may result in higher color stability than for conventional ones. Therefore, this study aimed to assess the color stability of three different bulk‐fill composites and one conventional resin composite with a higher filler load after 1 week and 1 month of immersion in different drinks. The resin composite materials that were tested demonstrated significantly different color changes after immersion in the four solutions during both evaluation periods. Immersion in coffee and red wine showed noticeable staining of all the materials. The discoloration effect of staining solutions on the resin composites depends both on the material composition and on the pigment types found in the solutions.     

Synthesis of β-myrcene-based macroporous nanocomposite foams: Altering the morphological and mechanical properties by using organo-modified nanoclay

Organo-modified nanoclay incorporated high internal phase emulsions (HIPEs) were successfully used for the preparation of macroporous nanocomposite foams. Due to the aim of obtaining mechanically improved foams, HIPEs were prepared by using a monomer mixture composed of β-myrcene and ethylene glycol dimethacrylate. Accordingly, two groups of macroporous nanocomposite foams were synthesized depending on the nanoclay type. The morphological analysis demonstrated that the pore openness of the resulting nanocomposites were significantly improved due to the decrease in the average cavity size and increase in the interconnected pore size. In terms of mechanical properties, it was found that filling 1 wt% of nanoclay which is surface modified by hydrogenated tallow lead to a 33% of increment in the compression modulus, as compared to the neat foam. However, loading 5 wt% of nanoclay having octadecylamine and aminopropyltriethoxysilane surface groups caused only 11% of increment in the compression modulus, as compared to the neat foam.     

Experimental and theoretical investigation of 3-amino-1,2,4-triazole-5-thiol as a corrosion inhibitor for carbon steel in HCl medium

The inhibition effect of 3-amino-1,2,4-triazole-5-thiol (3ATA5T) was investigated in 0.5 M HCl on carbon steel (CS) by electrochemical impedance spectroscopy and potentiodynamic measurements at various concentrations and temperatures. Results showed that the correlation between experimental (inhibition efficiencies, ΔG_ads, E_a) and quantum calculation parameters (dipole moment, E_HOMO, E_LUMO). The high inhibition efficiency was declined in terms of strongly adsorption of protonated inhibitor molecules on the metal surface and forming a protective film.     

Anodizing and corrosion behaviour of aluminium

In this study, aluminum was anodized in 0.4 M H₂SO₄ + 0.145 M H₃BO₃ solution by means of potentiostatic method. In first step, the most appropriate conditions (anodizing voltage and period) were determined. The voltage-current behavior was investigated between 0 to 30 V and oxide formation potential (15 V) was determined. Then chorono-amperometric measurement was obtained at this potential during 2 hours. Therefore, anodizing process was applied at 15 V between aluminium anode and mild steel cathode. In the second step, the corrosion performance of non-anodized (Al) and anodized samples (Al₂O₃) have been investigated in 3.5% NaCl solution by using electrochemical impedance spectroscopy and polarization techniques. The interface between metal and solution was modeled with the equivalent circuit successfully. The circuit’s elements were calculated with Ivium Soft fitting program. The polarization curves were obtained between −1.8 V and 0.5 V potential ranges. The experimental results proved that the thickness and quality of oxide film was improved with help of anodizing process. Thus the corrosion resistance of anodized aluminum is significantly increased.     

Ochratoxin A and Brewing Technology: A Review

Ochratoxins are a hazardous group of mycotoxins produced as secondary metabolites by several fungi of the Aspergillus and Penicillium families. Ochratoxins have been detected and determined in foods and beverages, including barley, malt and beer, at ppb levels. Varied analytical methods have been developed for the detection of ochratoxin A [OTA] in cereals and beer. Ochratoxin A has hazardous effects on health and has been classified within group 2B, as a possible human carcinogen by IARC. Scientists have expressed great concern about the presence of ochratoxin A in foods. In this article, chemical structure, biosynthesis by microorganisms, analytical methods for testing, regulations, changes during brewing, and detoxification of OTA, are reviewed. Beer poses very little risk as a source of ochratoxin in the diet.     

Optimization of suspension parameters to improve impact harshness of road vehicles

This paper illustrates the development and implementation of a parameter optimization methodology to improve impact harshness (IH) of road vehicles. A full ADAMS model of a small commercial vehicle is used as the IH test vehicle. The methodology involves the use of design of experiments methods together with response surface methodology. Significant design parameters affecting IH of the vehicle are first determined by the screening experiments. Once the critical parameters are identified, they are optimized to achieve improvement in the IH by constructing response surface. The optimization results indicate that the selected suspension parameters are capable of improving IH performance of the full vehicle ADAMS model by minimizing longitudinal and vertical acceleration responses. The results also show that considerable improvement can be obtained by using the proposed parameter optimization methodology.