The structure of latherin,a surfactant allergen protein from horse sweat and saliva

Latherin is a highly surface-active allergen protein found in the sweat and saliva of horses and other equids. Its surfactant activity is intrinsic to the protein in its native form, and is manifest without associated lipids or glycosylation. Latherin probably functions as a wetting agent in evaporative cooling in horses, but it may also assist in mastication of fibrous food as well as inhibition of microbial biofilms. It is a member of the PLUNC family of proteins abundant in the oral cavity and saliva of mammals, one of which has also been shown to be a surfactant and capable of disrupting microbial biofilms. How these proteins work as surfactants while remaining soluble and cell membrane-compatible is not known. Nor have their structures previously been reported. We have used protein nuclear magnetic resonance spectroscopy to determine the conformation and dynamics of latherin in aqueous solution. The protein is a monomer in solution with a slightly curved cylindrical structure exhibiting a ‘super-roll’ motif comprising a four-stranded anti-parallel β-sheet and two opposing α-helices which twist along the long axis of the cylinder. One end of the molecule has prominent, flexible loops that contain a number of apolar amino acid side chains. This, together with previous biophysical observations, leads us to a plausible mechanism for surfactant activity in which the molecule is first localized to the non-polar interface via these loops, and then unfolds and flattens to expose its hydrophobic interior to the air or non-polar surface. Intrinsically surface-active proteins are relatively rare in nature, and this is the first structure of such a protein from mammals to be reported. Both its conformation and proposed method of action are different from other, non-mammalian surfactant proteins investigated so far.     

Reliability assessment of 3D space frame structures applying stochastic finite element analysis

Throughout design development of satellite structure, stress engineer is usually challenged with randomness in applied loads and material properties. To overcome such problem, a risk-based design is applied which estimates satellite structure probability of failure under static and thermal loads. Determining probability of failure can help to update initially applied factors of safety that were used during structure preliminary design phase. These factors of safety are related to the satellite mission objective. Sensitivity-based analysis is to be implemented in the context of finite element analysis (probabilistic finite element method or stochastic finite element method (SFEM)) to determine the probability of failure for satellite structure or one of its components.     

Non-catalytic autothermal gasification of woody biomass

The non-catalytic autothermal gasification of woody biomass with air and steam mixtures is thermodynamically and experimentally investigated. A laboratory-scale fixed-bed downdraft reactor was used to gasify fine-grained woody biomass particles (German conifer, mean particle size = 133.7 μm) at atmospheric pressure and at 900-1020 K, with an equivalence ratio (ER) in the range 0.3-0.4 and a steam-to-biomass ratio (SB) in the range 0-0.6. The gasification efficiency and carbon conversion peaked at 35% and 83%, respectively, for ER = 0.4 and SB = 0.6. Hydrogen yield increased with both ER and SB within the ranges considered. The corresponding volumetric lower heating value of the dry gaseous product varied from 2.0 to 3.4 MJ/Nm³.     

Information modelling in the construction industry: The information engineering approach

Modelling of knowledge in the construction industry is a cumbersome task because of the large amount of data involved and the lack of automated information-modelling tools. Adoption of a method and an automated CASE (Computer-Aided Software Engineering) tool could eliminate many problems encountered in the development of information systems in the construction industry. In particular, this approach may help to assess the information requirements and define strategies for such information systems. The Information Engineering Method (IEM) is introduced to illustrate hoar the conceptual models may be improved by using this method. Additionally Texas Instruments' Information Engineering Facility (IEF?) CASE tool is described to illustrate the advantages of automating such a method. The introduction of conceptual modelling in the construction industry using data and process models should lead to a better structuring of information. This should result in the development of well defined and structured, not ad hoc, applications. This conceptual modelling approach using information engineering is currently being used at the University of Salford to study the potential development of an integrated database (design, procurement and management of construction) for the construction industry. The case study describes the information analysis phase of the procurement process included towards the end of this paper.     

Effect of communication media on developmental relationships: Self-reported and observed behaviors

This study examined the effect of four communication modes (computer-based video teleconferencing, computer-based electronic chat, telephone, and face-to-face) on developmental interactions between dyads; specifically on the transmission of psychosocial versus instrumental information. The dyads consisted of undergraduates at a southeastern university. One member of the dyad was an incoming first year student; the second member was an upper division student who served as a developmental coach. The study was experimental in design, which controlled the amount of interaction, the frequency of interaction, and prior acquaintanceship of the dyadic pair. The small amount of variance attributable to communication mode suggests that people matter more than the machines. Specifically, in terms of implementing non-face-to-face developmental programs, it might be more useful to focus on reducing the variability in the coaches’ behaviors through selection or training, than to focus on communication mode. Additionally, independent observers watched and rated the dyadic interactions to provide a third point of view. There was very little overlap between coach and trainee perceptions, although there was considerable agreement between the raters’ and coaches’ ratings.     

Sorption-desorption of ionogenic compounds at the mineral-water interface: study of metal oxide-rich soils and pure-phase minerals

Sorption of the ionic compounds 2,4-D and quinmerac onto iron oxide-rich, variable charged soils was strongly influenced by mineralogy, particularly soil iron and aluminum oxides, whereas sorption of the neutral norflurazon was only related to total soil C. An appreciable fraction of the mass sorbed in stirred-flow studies was easily desorbed by deionized water, and desorption of ionic compounds was initially more rapid than sorption. This sorption-desorption behavior, although contrary to desorption hysteresis commonly observed in batch studies, suggests that the reversibly sorbed fraction is weakly bound to the soil surface. 2,4-D sorption to iron oxide-rich soils and pure-phase metal oxides appears to be driven by nonspecific electrostatic attraction, with specific electrostatic attraction and van der Waals interactions being secondary. Both the carboxylate and the heterocyclic N groups may participate in sorption of quinmerac, facilitated by specific and nonspecific electrostatic attraction and surface complexation. The heterocyclic N, amine, and carbonyl groups of norflurazon do not appear to interact with soil minerals.     

Development and validation of dry reagent time-resolved fluoroimmunoassays for zeranol and alpha-zearalenol to assist in distinguishing zeranol abuse from Fusarium spp. toxin contamination in bovine urine

Zeranol, an oestrogenic growth promoter in food animals, is banned within the European Union (EU). However, commercially available immunoassay kits for zeranol cross-react with toxins formed by naturally occurring Fusarium spp. fungi, leading to false-positive screening results. This paper describes the validation of a specificity enhanced, rapid dry reagent time-resolved fluoroimmunoassay (TR-FIA) for zeranol (recovery 99%, limit of detection 1.3 ng ml(-1)) demonstrating that up to 150 ng ml(-1) of Fusarium spp. toxins in urine do not lead to false-positive results. This assay will assist EU Member States to implement Council Directive 96/23/EC, which requires states to monitor for potential abuses of zeranol. A similar TR-FIA for the Fusarium spp. toxin alpha-zearalenol, using the same sample extract, is also described (recovery 68%, limit of detection 5.6 ng ml(-1)). Only the addition of diluted sample extract is required to perform these dry-reagent TRFIAs, the results being available within 1h of extract application. The EU-funded project 'Natural Zeranol' (FAIR5-CT97-3443) will use these fluoroimmunoassays to screen bovine urine in four Member States to gather data on the seasonality of Fusarium spp. toxin contamination of urine and the incidence of zeranol screening test positives.