Inactivation of pathogens on pork by steam-ultrasound treatment

The objective of the study was to evaluate a new pathogen inactivation concept that combines application of pressurized steam simultaneously with high-power ultrasound through a series of nozzles. On skin and meat surfaces of pork jowl samples, counts of total viable bacteria were reduced by 1.1 log CFU/cm(2) after treatment for 1 s and by 3.3 log CFU/cm(2) after treatment for 4 s. The mean reduction of 1.7 to 3.3 log CFU/cm(2) on the skin surface was significantly higher than the reduction of 1.1 to 2.5 log CFU/cm(2) on the meat surface. The inactivation of Salmonella Typhimurium, Salmonella Derby, Salmonella Infantis, Yersinia enterocolitica, and a nonpathogenic Escherichia coli was studied on inoculated samples that were treated for 0.5 to 2.0 s. With one exception, no significant differences in reduction were observed among the bacterial types. After treatment for 0.5 s, the 0.9-to 1.5-log reductions of E. coli were significantly higher than the 0.4- to 1.1-log reductions for Salmonella and Y. enterocolitica. Overall, reductions increased by increasing treatment time; reductions were 0.4 to 1.5 log CFU/cm(2) after treatment for 0.5 s and 2.0 to 3.6 log CFU/cm(2) after treatment for 2 s. Reductions on the skin (1 to 3.6 log CFU/cm(2)) were significantly higher than reductions on the meat surface (1 to 2.5 log CFU/cm(2)). The reduced effect on the meat surface may be explained by greater protection of bacteria in deep structures at the muscle surface. No significant difference in reduction was observed between samples inoculated with 10(4) CFU/cm(2) and those inoculated with 10(7) CFU/cm(2), and cold storage of samples for 24 h at 5°C after steam-ultrasound treatment did not lead to changes in recovery of bacteria.     

Photoproduction of H2 by wildtype Anabaena PCC 7120 and a hydrogen uptake deficient mutant: from laboratory experiments to outdoor culture

We have analyzed the filamentous cyanobacterium Anabaena PCC 7120 (wildtype) containing one nitrogenase, one uptake hydrogenase and one bidirectional hydrogenase and its hydrogen uptake deficient mutant AMC 414 for their H₂ production capacities. Anabaena PCC 7120 and AMC 414 had similar growth rates in turbidostat mode with increased growth rates at higher light intensity. Rates of C₂H₂ reduction were similar for both strains. In contrast to the wildtype, AMC 414 produced H₂ in a PhotoBioReactor (PhBR) using air as the lifting gas. The rate of H₂ production increased with light intensity and was not even saturated at 456 μEm⁻² s⁻¹. H₂ production increased significantly when replacing the air with argon. The maximal H₂ production during outdoor conditions was recorded using AMC 414 with a peak at 14.9 ml H₂ h⁻¹ l⁻¹. Despite the relatively high production, maximal efficiency of solar energy to H₂ conversion was only 0.042%. A molecular method was developed to analyze the relative abundancies of weight and mutant in competition experiments in the PhBR.     

How to create a space for stakeholders’ involvement in construction

The aim is to investigate how stakeholders can participate in the early phases of construction projects and how relevant insights can be gathered from stakeholders with very different backgrounds and interests. To gain these insights, it is important to understand how a space can be created to facilitate communication between professionals and stakeholders. The research draws on the literature of design and user-driven innovation in order to get a richer understanding of stakeholders’ involvement in construction. The method applied is research based on three stakeholder workshops, interviews and observations from a single case study. The findings provide valuable information on six aspects of who the stakeholders are in construction, what these stakeholders can do in construction when involved, how to involve these stakeholders in a construction project, how a space can be staged and facilitated for the meeting of stakeholders, and what kind of information can be collected from the stakeholders to influence the development process. The findings show how creating and facilitating a workshop as a socio-technical space across boundaries can overcome barriers and improve stakeholders’ involvement and thus provide better insights into their needs, values and concerns.     

The occurrence of Listeria monocytogenes in cheese from a manufacturer associated with a case of listeriosis

A case of listeriosis was associated with the consumption of a soft cheese produced in England. Goats cheese and other products from the same food manufacturer were examined for the presence of Listeria over the following 11 months. Listeria monocytogenes was isolated from 16 of 25 cheese samples on retail sale, 12 of 24 cheese samples obtained directly from the factory, and from shelving within the plant. Phage-typing of 68 isolates of L. monocytogenes from cheese samples and the factory showed that 66 (97%) were indistinguishable from the strain isolated from the patient's cerebrospinal fluid and stool. L. monocytogenes was not isolated from seven goats milk or two yoghurt samples. Listeria innocua was isolated from 10 cheese samples, two of which contained no other species of Listeria. Levels of L. monocytogenes shortly after production were low (<10/g), but were higher (10⁵–10⁷ cfu/g) in six of the 16 cheese samples obtained from retail outlets. Multiplication of L. monocytogenes was demonstrated in cheeses contaminated at the factory and held at 4°C in the laboratory.     

Virtual reality in posturography.

Balance dysfunctions are common, especially among elderly people. Present methods for the diagnosis and evaluation of severity of dysfuntion have limited value. We present a system that makes it easy to implement different visual and mechanical perturbations for clinical investigations of balance and visual-vestibular interaction. The system combines virtual reality visual stimulation with force platform posturography on a moving platform. We evaluate our contruction's utility in a classification task between 33 healthy controls and 77 patients with Ménière's disease, using a series of tests with different visual and mechanical stimuli. Responses of patients and controls differ significantly in parameters computed from stabilograms. We also show that the series of tests achieves a classification accuracy slightly over 80% between controls and patients.     

The Deuterium Isotope Effect as a Tool to Investigate Enzyme Catalysis: Proton-Transfer Control Mechanisms in Cytochrome c Oxidase

Cytochrome c oxidase is a membrane-bound redox-driven proton pump. The coupling of the exergonic electron-transfer reactions from cytochrome c to oxygen to proton translocation across the membrane requires control of internal electron- and proton-transfer reactions. In this work, we focus on the kinetics of electron and proton transfer during those reaction steps that are coupled to proton pumping in cytochrome c oxidase. The results show that during the first pumping step (peroxy → oxoferryl transition), proton transfer regulates intramolecular electron transfer. The proton transfer takes place in two steps: (1) Internal proton transfer from a protonatable group, proposed to be Glu(I-286), in the so-called D-pathway, to an oxygen intermediate at the binuclear center (τ ≅ 100 μs); (2) Rapid re-protonation of Glu(I-286) from the bulk solution (τ < 100 μs). Only after proton uptake from solution the last (fourth) electron is transferred “one step closer” towards the binuclear center (from Cu_A to heme a). During the second proton-pumping step (oxoferryl → oxidized), this electron is transferred to the binuclear center, linked to the uptake of a proton through the D-pathway. The electron-transfer rate displays a kinetic-isotope effect (k_H/k_D) of 6 ± 1 (in a pH range in which the pH dependence of the rate is small), which indicates that the electron transfer is rate-limited by the proton transfer. The entry into the D-pathway (around Asp(I-132)) is composed of a cluster of negatively-charged amino acid residues together with a number of histidines, forming a so-called proton-collecting antenna designed to allow rapid protonation of groups within the proton-transfer pathway.     

Absence of snapshot memory of the target view interferes with place navigation learning by rats in the water maze.

Contribution of visual and nonvisual mechanisms to spatial behavior of rats in the Morris water maze was studied with a computerized infrared tracking system, which switched off the room lights when the S entered the inner circular area of the pool with an escape platform. 10 naive male rats trained under light–dark (LD) conditions found the escape platform more slowly than 10 male rats trained in permanent light (LT). After group members were swapped, the LT-pretrained rats found under LD conditions the same target faster and eventually approached latencies attained during LT navigation. Performance of LD-trained rats deteriorated in permanent darkness (PD) but improved with continued PD training. Thus LD navigation improves gradually by procedural learning (extrapolation of the start-target azimuth into the zero-visibility zone) but remains impaired by lack of immediate visual feedback rather than by absence of the snapshot memory of the target view. (PsycINFO Database Record (c) 2010 APA, all rights reserved)