Plant functional modelling as a basis for assessing the impact of management on plant safety

A major objective of the present work is to provide means for representing a chemical process plant as a socio-technical system, so as to allow hazard identification at a high level in order to identify major targets for safety development. The main phases of the methodology are: (1) preparation of a plant functional model where a set of plant functions describes coherently hardware, software, operations, work organization and other safety related aspects. The basic principle is that any aspect of the plant can be represented by an object based upon an Intent and associated with each Intent are Methods, by which the Intent is realized, and Constraints, which limit the Intent. (2) Plant level hazard identification based on keywords/checklists and the functional model. (3) Development of incident scenarios and selection of hazardous situation with different safety characteristics. (4) Evaluation of the impact of management on plant safety through interviews. (5) Identification of safety critical ways of action in the management system, i.e. identification of possible error- and violation-producing conditions.     

Reliability-based calibration of load duration factors for timber structures

The load bearing capacity of timber structures decrease with time depending on the type of load and timber. Based on representative limit states and stochastic models for timber structures, load duration factors are calibrated using probabilistic methods. Load duration effects are estimated on basis of simulation of realizations of wind, snow and imposed loads in accordance with the load models in the Danish structural codes. Three damage accumulation models are considered, namely Gerhards model, Barrett and Foschi’s model and Foschi and Yao’s model. The parameters in these models are fitted by the Maximum Likelihood Method using data relevant for Danish structural timber and the statistical uncertainty is quantified. The reliability is evaluated using representative short- and long-term limit states, and the load duration factor k_mod is estimated using the probabilistic model such that equivalent reliability levels are obtained using short- and long-term design equations. Time variant reliability aspect is considered using a simple, representative limit state with time variant strength and simulation of the whole life time load processes.     

Eight years of wind measurements from scatterometer for wind resource mapping in the Mediterranean Sea

Eight years of wind observations from the SeaWinds scatterometer instrument on the National Aeronautics and Space Administration QuikScat satellite and in situ data from 11 locations in the Mediterranean have been considered. The data have been co‐located in time and space, and it is shown that the scatterometer is able to provide similar long‐term statistics as available from buoy data, such as annual and monthly wind indexes. Such statistics is useful to give an overview of the climatology in the different areas. The correlation between QuikScat and in situ observations is degraded towards the coast, giving indication of how well the scatterometer can represent the coastal winds. The degradation is stronger in areas with strong spatial variability. The QuikScat winds are gridded into a 0.25° by 0.25° grid to produce seasonal and annual means of the offshore wind conditions over the Mediterranean. Copyright © 2010 John Wiley & Sons, Ltd.     

The survival and persistence in the human gastrointestinal tract of five potential probiotic lactobacilli consumed as freeze-dried cultures or as probiotic sausage

Among five lactobacilli (L. plantarum MF1291, MF1298, DC13, L. pentosus MF1300 and L. salivarius DC5) which were administrated as freeze-dried cultures for 17 volunteers, MF1298 and DC13 were the most frequently reisolated strains in faeces demonstrating the human gastric survival of these strains. Furthermore, MF1298 and DC13 persisted in the same volunteer after ended intake, suggesting host-specific persistence behaviour. When MF1298 was administrated as sausage fermented with this strain, the number of volunteers harbouring MF1298 increased from 4 to 10 indicating that the sausage matrix protects the survival through the gastrointestinal tract (GIT).     

Responses of Listeria monocytogenes to acid stress and glucose availability monitored by measurements of intracellular pH and viable counts

Physiological aspects of the response of Listeria monocytogenes to acidic conditions and effect of glucose availability were studied by fluorescence ratio-imaging microscopy (FRIM) as compared with traditional viable counts. Three types of experiments were conducted: (i) static with measurements of intracellular pH (pHi) at extracellular pH (pHo) values ranging from pH 3.0 to 6.0 at 0.5 pH unit intervals; (ii) kinetic with monitoring of bacterial responses to changes in the pHo from the value of 6.0 to 4.0 or 3.0; (iii) survival experiments studying bacterial recovery in response to a shift to favourable conditions after a treatment at low pH. All the experiments were performed at three levels of glucose in the medium (0, 1, and 10 mM). Both survival and pHi were greatly affected by pHo and glucose availability with the highest values for CFU and pHi at highest glucose concentration and pHo values in the medium in all trials. A high correlation (R2 = 0.995) between pHi and CFU counts was observed. The pH gradient started to collapse at pHo 4 and below for trials with glucose in the medium and at pHo 5.5 and below without glucose. A recovery step was proposed after the apparently lethal treatment to assess cell viability by FRIM.     

Engineering the C-region of human insulin-like growth factor-1: implications for receptor binding

Recombinant wild-type human IGF-1 and a C-region mutant in whichresidues 28–37 have been replaced by a 4-glycine bridge(4-Gly IGF-1) were secreted and purified from yeast. An IGF-1analogue in which residues 29–41 of the C-region havebeen deleted (mini IGF-1) was created by site-directed mutagenesisand also expressed. All three proteins adopted the insulin-foldas determined by circular dichroism. The significantly raisedexpression levels of mini IGF-1 allowed the recording of two-dimensionalNMR spectra. The affinity of 4-Gly IGF-1 for the IGF-1 receptorwas {small tilde}100-fold lower than that of wild-type IGF-1and the affinity for the insulin receptor was {small tilde}10-foldlower. Mini IGF-1 showed no affinity for either receptor. Notonly does the C-region of IGF-1 contribute directly to thefree energy of binding to the IGF-1 receptor, but also the absenceof flexibility in this region eliminates binding altogether.As postulated for the binding of insulin to its own receptor,it is proposed that binding of IGF-1 to the IGF-1 receptor alsoinvolves a conformational change in which the C-terminal B-regionresidues detach from the body of the molecule to expose theunderlying A-region residues.     

Lipid Oxidation and Degradation Products in Raw Materials: Low‐Fat Topical Skin‐Care Formulations

Topical skin formulations with a lipid content below 15% were stored for 6 months at 5, 20, or 40 °C or for 2 weeks at 50 °C in darkness or at 20 °C with exposure to light for 6 months. The volatile lipid‐oxidation compounds formed during this storage period were compared to those formed in the raw materials during 3 months of accelerated stability storage at 40 °C. The volatile compounds were collected by dynamic headspace and analyzed using gas chromatography–mass spectrometry. It was possible to link eight out of nine volatile compounds detected during storage of topical skin formulations to the raw materials. In addition, a possible link between the appearance of butane nitrile and the decomposition of an initiator used for polyacrylate crosspolymer‐6 production was observed. The polymer may originate from texture modifiers added to the topical skin formulation or from plastics used for packaging of topical skin formulations. Furthermore, six well‐known lipid‐oxidation and nonenzymatic browning products were suggested to originate from the two raw materials, tricaprylin/tricaprin and coconut oil.     

Analysis of histidine phosphorylation using tandem MS and ion-electron reactions

Phosphorylation of proteins is essential in intracellular signal transduction pathways in eukaryotic and prokaryotic cells. Histidine phosphorylation plays an important role in two-component signal transduction in bacteria. In this study, we describe the characterization of a synthetic histidine-phosphorylated peptide with four different mass spectrometric (MS) fragmentation techniques: Collision-induced dissociation (CID), electron capture dissociation, electron-transfer dissociation, and electron detachment dissociation. Furthermore, LC-MS methods were developed to detect histidine-phosphorylated peptides, which are acid-labile, in more complex samples. From these results, we concluded that nonacidic solvent systems or fast LC methods provide the best conditions for separation of histidine-phosphorylated peptides prior to electrospray ionization mass spectrometry analysis. Electron-based fragmentation methods should be used for determination of histidine phosphorylation sites, since CID results in very facile phosphate-related neutral losses. The developed LC-MS/MS methods were successfully applied to a tryptic digest of the cytoplasmic part of the histidine kinase EnvZ, which was in vitro autophosphorylated. Finally, a new method is described for nonretentive solid-phase extraction of histidine-phosphorylated peptides using polymeric Strata-X microcolumns.     

Information and computing technology and the gap between school pedagogy and children's culture

This article focuses on the gap between the use of Information and Computing Technology (ICT) in schools and the use made of ICT in children's everyday life outside school. Particular emphasis is placed on the communities of practice that young people create through their use of digital technology. The article is based on data collected over five years in Denmark. Overall, the article raises questions about the future of teaching and learning both in school and out of school.