The hygienic working practices of maintenance personnel and equipment hygiene in the Finnish food industry

The hygienic working practices of the maintenance personnel as well as the hygiene of the equipment in the food industry were investigated with questionnaires and microbial surveys. The protective clothing, washing of hands and tools as well as avoiding foreign bodies left on the production lines should be targeted when the hygienic working practices are developed for maintenance personnel. Based on the questionnaire to food processors, packaging machines, conveyers, dispensers, slicing and cooling machines were considered the most problematic pieces of equipment hygienically mainly because of poor hygienic design. In order to improve food safety, both the training of maintenance personnel in food hygiene and equipment design should be more emphasised.     

Susceptibility of Listeria monocytogenes strains to disinfectants and chlorinated alkaline cleaners at cold temperatures

Minimal inhibitory concentration (MIC), suspension and biofilm tests were used in evaluating the disinfecting efficacy of eight commercially available disinfectants and four chlorinated alkaline cleaners against 10 strains of Listeria monocytogenes at refrigerated temperatures. The adaptive response and cross-adaptation of L. monocytogenes to the disinfectants and chlorinated alkaline cleaners were investigated. The bactericidal components in the agents used were chlorine, quaternary ammonium compound (QAC), peracetic acid, ethanol and isopropanol. With some exceptions the disinfectants were efficient against the L. monocytogenes strains. One alkaline hypochlorite containing disinfectant was not efficient in the suspension and MIC tests at the lowest concentration recommended by the manufacturer. The chlorinated alkaline cleaners were effective against L. monocytogenes. A QAC-based disinfectant was found to be the least-effective agent on both glass bead-blasted polyethylene and stainless-steel surfaces. Adaptive and cross-adaptive responses of L. monocytogenes strains were observed towards the QAC-based agent, but over 2-fold increases to other agents were not observed. These results suggest that the adaptive responses of L. monocytogenes to disinfectants or chlorinated alkaline cleaners are of a minor concern.     

On studying methods for cleaning dielectric oil for impregnation of high-voltage pulse capacitors with film dielectric

Methods for cleaning commercial T-1500 dielectric oil with different adsorbents are studied. The oil is intended for impregnation of high-voltage pulse capacitors with film dielectric.     

Ozonolysis of cyclododecene

Ozonolysis of cyclododecene was carried out to produce an w-formyl carboxylic acid (12-oxododecanoic acid) which is derived from zwitterion and aldehyde moiety that are formed during the reaction. The ozonolysis was performed to examine the product distribution under such reaction variables as temperature, kinds of solvent, and presence of catalyst. The yield of polymeric ozonide, which is undesirable product, was measured to be dominantly 86% without pyridine catalyst, whereas, only 10.25% with the catalyst. The optimum reaction condition was to be in MC (methylene chloride) solvent, and in the presence of equimolar olefin and pyridine catalyst at O°C, at which the yields of polymeric ozonide, 1,12-dodecanedialdehyde, 1,12-dodecanedicarboxylic acid, and 12-oxo-dodecanoic acid were 10.25%, 26.72%, 26.31%, and 36.72%, respectively.     

Latent catalyst effects in halogen‐free epoxy molding compounds for semiconductor encapsulation

Latent catalyst effects were investigated to improve the physical properties of halogen‐free epoxy molding compounds (EMCs) for semiconductor encapsulation. In this study, biphenyl‐type resins were used as the epoxy and hardener resin for halogen‐free EMCs to obtain high flame‐retardant properties and high filler contents. Latent catalyst effects were examined with two kinds of EMC compositions, halogen‐free EMCs and conventional EMC compositions. We used triphenylphosphine‐benzoquinone salt (TPP‐BQ) as a latent catalyst. Spiral flow and gel time were measured to investigate the change in moldability with the latent catalyst. We measured package fail, moisture absorption, and delamination for reliability evaluation and flexural strength, flexural modulus, and adhesion for mechanical properties to examine latent catalyst effects. An improvement in moldability, reliability, and the mechanical properties were observed in two types of halogen‐free EMCs with TPP‐BQ as a latent catalyst. These phenomena were seen in conventional EMCs, including o‐cresol novolac epoxy resin. The cure kinetics of these systems were investigated by differential scanning calorimetry with an isothermal approach to explain these phenomena. The results indicate that the improvement in moldability in halogen‐free EMCs with TPP‐BQ was due to the low conversion rate of this system, and the increase in mechanical properties was attributed to the high conversion of curing reaction. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2287–2299, 2005     

Properties of chitosan‐based biopolymer films with various degrees of deacetylation and molecular weights

An increase in the depolymerization of chitosan was found with an increased concentration of sodium perborate. Acetic anhydride was added to reacetylated chitosan in a molar ratio per gulcosamine unit, and the amide I band of IR spectra changed with the addition of acetic anhydride. Sixteen chitosans with various molecular weights (MWs) and degrees of deacetylation (DODs) were prepared. X‐ray diffraction patterns indicated their amorphous and partially crystalline states. Increases in the chitosan MW and DOD increased the tensile strength (TS). TS of the chitosan films ranged from 22 to 61 MPa. However, the elongation (E) of chitosan films did not show any difference with MW. TS of chitosan films decreased with the reacetylation process. However, E of chitosan films was not dependent on DOD. The water vapor permeabilities (WVPs) of the chitosan films without a plasticizer were between 0.155 and 0.214 ng m/m² s Pa. As the chitosan MW increased, the chitosan film WVP increased, but the values were not significantly different. Moreover, the WVP values were not different from low DOD to high DOD. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3476–3484, 2003     

Effect of reaction kinetics of polymer electrolyte on the ion‐conductive behavior for poly(oligo oxyethylene methacrylate)–LiTFSI mixtures

The effect of the reaction kinetics on the ionic conductivity for a comblike‐type polyether (MEO) electrolyte with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) was characterized by DSC, complex impedance measurements, and ¹H pulse NMR spectroscopy. The ionic conductivity of these electrolytes was affected by the reaction condition of the methacrylate monomer and revealed by the glass transition temperature (T_g), spin–spin relaxation time (T₂), steric effects of the terminal groups, and the number of charge carriers indicated by the VTF kinetic parameter. In this system, the electrolytes prepared by the reaction heating rate of 10°C/min of MEO–H and 15°C/min of MEO–CH₃ showed maximum ionic conductivity, σ_i, two to three times higher in magnitude than that of the σ_i of the others at room temperature. As experimental results, the reaction kinetic rate affected the degree of conversion, the ionic conductivity, and the relaxation behaviors of polyether electrolytes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2149–2156, 2003     

Memory effects of all‐solution‐processed oxide thin‐film transistors using ZnO nanoparticles

Abstract— Non‐volatile memory effects of an all‐solution‐processed oxide thin‐film transistor (TFT) with ZnO nanoparticles (NPs) as the charge‐trapping layer are reported. The device was fabricated by using a soluble MgInZnO active channel on a ZrHfO^x gate dielectric. ZnO NPs were used as the charge‐trapping site at the gate‐insulator—channel interface, and Al was used for source and drain electrodes. Transfer characteristics of the device showed a large clockwise hysteresis, which can be used to demonstrate its memory function due to electron trapping in the ZnO NP charge‐trapping layer. This memory effect has the potential to be utilized as a memory application on displays and disposable electronics.     

Acoustic emission from gas-filled coal under triaxial compression

Acoustic emission (AE) experiments have been performed on gas-saturated coal specimens under conventional triaxial compression. The AE characteristics were investigated for a methane gas flow through the coal specimen. One AE parameter, AE count, when normalized by the total count number was used to represent the damage evolution in the gassy coal. It is shown that this AE parameter is a reasonable indicator for damage occurring within the coal specimen since its envelope has almost the same shape as the complete stress–strain curve, except for a short time delay. In addition, the change in AE count is highly consistent with the change in coal permeability. Test results also show that methane containing coal emits a small number of AE events before entering the yield stage. AE activity gradually increases during the yield process up to the peak stress. The lowest permeability corresponds to the highest AE activity, implying failure will soon occur. An AE based constitutive model was constructed and the theoretical results agree well with those of experiments.