Enumerating sparse organisms in ships' ballast water: why counting to 10 is not so easy

To reduce ballast water-borne aquatic invasions worldwide, the International Maritime Organization and United States Coast Guard have each proposed discharge standards specifying maximum concentrations of living biota that may be released in ships' ballast water (BW), but these regulations still lack guidance for standardized type approval and compliance testing of treatment systems. Verifying whether BW meets a discharge standard poses significant challenges. Properly treated BW will contain extremely sparse numbers of live organisms, and robust estimates of rare events require extensive sampling efforts. A balance of analytical rigor and practicality is essential to determine the volume of BW that can be reasonably sampled and processed, yet yield accurate live counts. We applied statistical modeling to a range of sample volumes, plankton concentrations, and regulatory scenarios (i.e., levels of type I and type II errors), and calculated the statistical power of each combination to detect noncompliant discharge concentrations. The model expressly addresses the roles of sampling error, BW volume, and burden of proof on the detection of noncompliant discharges in order to establish a rigorous lower limit of sampling volume. The potential effects of recovery errors (i.e., incomplete recovery and detection of live biota) in relation to sample volume are also discussed.     

Creep behaviour of modified 9Cr-1Mo ferritic steel

Creep deformation and fracture behaviour of indigenously developed modified 9Cr-1Mo steel for steam generator (SG) tube application has been examined at 823, 848 and 873 K. Creep tests were performed on flat creep specimens machined from normalised and tempered SG tubes at stresses ranging from 125 to 275 MPa. The stress dependence of minimum creep rate obeyed Norton’s power law. Similarly, the rupture life dependence on stress obeyed a power law. The fracture mode remained transgranular at all test conditions examined. The analysis of creep data indicated that the steel obey Monkman-Grant and modified Monkman-Grant relationships and display high creep damage tolerance factor. The tertiary creep was examined in terms of the variations of time to onset of tertiary creep with rupture life, and a recently proposed concept of time to reach Monkman-Grant ductility, and its relationship with rupture life that depends only on damage tolerance factor. SG tube steel exhibited creep-rupture strength comparable to those reported in literature and specified in the nuclear design code RCC-MR.     

Three-dimensional mesoporous structures fabricated by independent stacking of self-assembled films on suspended membranes

We report an original iterative method for fabricating three-dimensional mesoporous structures by independently stacking multiple self-assembled block copolymer films supported by Si membranes. A first layer is formed on the substrate by a self-assembled PS-b-PMMA (polystyrene-block-poly(methyl methacrylate)) film. A porous, permeable Si membrane deposited on top of the first block copolymer film provides mechanical support, preventing pattern collapse during the wet developing used to selectively remove the PMMA component of the PS-b-PMMA film. A second, dense Si membrane is deposited to seal the porous membrane, resulting in an impermeable coating suspended atop the self-assembled mesoporous polystyrene structures. The process can then be iterated using the sealed membrane as the new substrate to support a subsequent self-assembled block copolymer film. This multilayer approach provides a flexible three-dimensional fabrication technique where, in each layer, pattern morphology, domain orientation and degree of ordering can be designed independently. Furthermore, the process is compatible with electron-beam directed assembly, used to achieve regular patterns with feature density multiplication at any level in the stack.     

Built-in electric field minimization in (In, Ga)N nanoheterostructures

(In, Ga)N nanostructures show great promise as the basis for next generation LED lighting technology, for they offer the possibility of directly converting electrical energy into light of any visible wavelength without the use of down-converting phosphors. In this paper, three-dimensional computation of the spatial distribution of the mechanical and electrical equilibrium in nanoheterostructures of arbitrary topologies is used to elucidate the complex interactions between geometry, epitaxial strain, remnant polarization, and piezoelectric and dielectric contributions to the self-induced internal electric fields. For a specific geometry-nanorods with pyramidal caps-we demonstrate that by tuning the quantum well to cladding layer thickness ratio, h(w)/h(c), a minimal built-in electric field can be experimentally realized and canceled, in the limit of h(w)/h(c) = 1.28, for large h(c) values.     

Petri nets‐based model for the analysis of NORIA protocol

Network rOle‐based Routing Intelligent Algorithm is a novel routing algorithm for wireless sensor networks, which combine various effective techniques in order to reduce energy consumption and improve data routes. This algorithm uses role assignment for distributing tasks over the network nodes and fuzzy logic for making decisions. There is a clear need for the use of formal methods to validate the correctness of the protocols as well as performance and functionality prior to the deployment of such algorithms in a real environment. This paper presents a formal and rigorous study of Network rOle‐based Routing Intelligent Algorithm. Prioritised‐timed coloured petri nets (PTCPNs) have been chosen as an appropriate modelling language. In this way, PTCPNs have been used to describe complete and unambiguous specifications of system behaviour, whereas CPNTools is used to evaluate the correctness of the protocol using state space exploration and for performance evaluation using simulation. Copyright © 2015 John Wiley & Sons, Ltd.     

Comparison of physicochemical pretreatments of banana peels for bioethanol production

Pretreatments with different concentrations of sulfuric acid (0, 0.5, and 1% v/v) and temperatures (28 and 121 °C at 103 kPa in an autoclave) were performed on banana peels (BP) milled by mechanical grinding and grinding in a blender as well as without grinding. Cellulose, hemicellulose, lignin, ash, and total and reducing sugar contents were evaluated. The highest yields of cellulose enzymatic hydrolysis (99%) were achieved with liquefied autoclaved BP treated with 0.5 and 1% acid after 48 h of hydrolysis. Ethanol production by Kluyveromyces marxianus fermentation was assayed using hydrolyzed BP at 10, 15, and 20% (w/w). The highest ethanol level (21 g/L) was reached after 24 h of fermentation with 20% (w/w) BP. Kinetics of the consumption of reducing sugars under this fermentation condition demonstrates the presence of a lag period (about 8 h). Thus, BP are a good source for ethanol production.     

Ling Heather Honey Authentication by Thixotropic Parameters

This paper assesses the actual reliability of four rheological parameters to help describe honeys that exhibit non-Newtonian behavior, being the most representative of which, ling heather (Calluna vulgaris (L.) Hull) honeys. Sampling included a representative number of unifloral ling heather honeys, non-unifloral honeys close to ling heather uniflorality, and other non-unifloral honeys containing ling heather. All experiments were performed at 25 °C and consisted on researching viscosity curves at different shear rates, as well as the time dependency of honey samples at a constant shear rate. Viscosity curves were correctly fitted by the Ostwald-de Waele model. Consistency coefficients (k) and flow behavior indexes (n) were calculated, and the Weltmann model was used to determine the stress decay behavior. The influence of honey moisture on k value was also researched. Hysteresis area and time-dependent thixotropic index B proved to be the most suitable parameters for a reliable ling heather honey authentication.     

Foodborne Salmonella-caused outbreaks in Catalonia (Spain), 1990 to 2003

In most developed countries, nontyphoid Salmonella is an important cause of sporadic cases and outbreaks of foodborne gastroenteritis. The aim of this study was to investigate the trend of foodborne Salmonella-caused outbreaks and number of cases, hospitalizations, and deaths and compare them with those caused by other infectious agents. The study was carried out in Catalonia, a region in northeastern Spain with a population of 6.5 million inhabitants, in 2002. All information on reported outbreaks of foodborne disease from 1990 to 2003 was reviewed. For each outbreak, the following variables were collected: year; setting (household, restaurant, school, hospital, nursing home, and others); number of cases, hospitalizations, and deaths; causal agent; and food vehicle involved. Of 1652 reported outbreaks, 1078 had a known causal agent. Among them, 871 (80.8%) were caused by Salmonella, with 14,695 cases, 1534 hospitalizations, and 4 deaths. The rate of hospitalization was higher in outbreaks due to Salmonella than in those caused by other infectious agents (rate ratio, 2.54; 95% confidence interval, 2.20 to 2.94). Forty-eight percent of Salmonella-caused outbreaks were eggborne, compared with 5.3% of those caused by other infectious agents (rate ratio, 1.40; 95% confidence interval, 1.33 to 1.48). The annual number of cases in household outbreaks of eggborne Salmonella rose over time (R2 = 0.82), but the number of outbreaks produced in other settings did not. Eggborne outbreaks caused by Salmonella in households are a major cause of disease, and increased preventive efforts are necessary, especially consumer education and awareness of the risk of eating food containing raw or slightly cooked eggs.     

Influence of sensory characteristics on the acceptability of dry-cured ham

The influence of different sensory attributes on the acceptability of dry-cured Iberian ham was studied. Partial least squares regression analysis showed that juiciness and several flavour traits were the major attributes positively influencing acceptability of dry-cured Iberian ham, whereas yellowness of the fat, dryness and fibrousness showed a negative influence. Using stepwise multivariate regression, juiciness and flavour intensity were the two traits that better explained the acceptability of dry-cured ham, the linear model obtained showing a regression coefficient of 0.526. The regression coefficient of acceptability with juiciness and flavour intensity was higher using a piecewise linear regression model (R²=0.759) showing, therefore, a discontinuous relationship between these variables. However, results on product acceptability have been obtained using trained panellists and it might be possible that the use of a consumer panel would change these conclusions.