Artificial ponds in a Mediterranean region (Andalusia,southern Spain): agricultural and environmental issues

A total of 16 543 artificial ponds were inventoried. Ninety‐one per cent of the ponds were classified as for farming use. Generally, the fraction of farm land converted to pond structures was close to that predicted from the average annual precipitation in the region. However, in several areas, this fraction was remarkably higher than the value predicted, probably due to excessive groundwater extraction. Overall, the naturalisation stage of ponds was poor. However, ponds sited on natural substrate basins had more structured‐marginal vegetation, compared with ponds of artificial substrate basins. Furthermore, other factors related to pond management might seriously limit their naturalisation stage. Despite the high abundance of ponds in Andalusia, our results suggest that, in order to improve the potential for biodiversity conservation in these environments, substantial structural and management changes are required.     

An Alternate Double–Single Track Proposal for High‐Speed Peripheral Railway Lines

This article presents alternate double–single track (ADST) lines as an alternative to double‐track lines. The idea consists of using single track where the infrastructure is very expensive (tunnels and viaducts) and double track where it is cheaper (smooth orography) combined with small changes in departure times so that trains may cross in the double‐track segments with no reduction in travel times. The solution is shown to be very efficient for traffic demands between 30 and 40 trains per day and the costs are reduced substantially (close to 40%). A linear programming program is given that (1) decides the optimal sequence of single and double tracks and (2) optimizes the timetables for the optimal or other alternative sequences. The Palencia–Santander line is used to illustrate the proposal and some suggestions are given to use the ADST lines in several countries.     

Meat quality in suckling lambs: effect of pre-slaughter handling

Thirty-three suckling lambs of the Manchega breed were used to compare the effects of pre-slaughter handling (PSH) on initial meat quality and at 7 days post-mortem. Lambs were distributed into three groups: electrically stunned (ESL; n=15), stunned using CO(2) (GSL; n=10) and slaughtered without previous stunning (USL; n=8). Meat quality was evaluated by examining pH, colour (L*, a*, b* values), water holding capacity (WHC), cooking loss (CL), shear force (SF) and drip loss (DL). At 24 h post-mortem, the highest pH corresponded to the USL group (P<0.05) whereas the lowest pH decline (pH(0)-pH(24)) corresponded to the GSL group (P<0.05). Differences in pH among groups disappeared after 7 days post-mortem. In general, PSH did not affect values of WHC, CL and colour parameters. After 7 days post-mortem, there were significant differences between groups in DL, this being lowest (P<0.05) in stunned animals. GSL resulted in more tender meat (lower SF value) than ESL and USL (P<0.05). Moreover, there was no blood splash in any of the carcasses of the GSL group.     

Molecular self-assembly at solid surfaces

Self-assembly, the process by which objects initially distributed at random arrange into well-defined patterns exclusively due to their local mutual interactions without external intervention, is generally accepted to be the most promising method for large-scale fabrication of functional nanostructures. In particular, the ordering of molecular building-blocks deposited at solid surfaces is relevant for the performance of many organic electronic and optoelectronic devices, such as organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs) or photovoltaic solar cells. However, the fundamental knowledge on the nature and strength of the intermolecular and molecule-substrate interactions that govern the ordering of molecular adsorbates is, in many cases, rather scarce. In most cases, the structure and morphology of the organic-metal interface is not known and it is just assumed to be the same as in the bulk, thereby implicitly neglecting the role of the surface on the assembly. However, this approximation is usually not correct, and the evidence gathered over the last decades points towards an active role of the surface in the assembly, leading to self-assembled structures that only in a few occasions can be understood by considering just intermolecular interactions in solid or gas phases. In this work we review several examples from our recent research demonstrating the apparently endless variety of ways in which the surface might affect the assembly of organic adsorbates.     

Prediction of phonon thermal transport in thin GaAs, InAs and InP nanowires by molecular dynamics simulations: influence of the interatomic potential

A number of different potentials are currently being used in molecular dynamics simulations of semiconductor nanostructures. Confusion can arise if an inappropriate potential is used. To illustrate this point, we performed direct molecular dynamics simulations to predict the room temperature lattice thermal conductivity λ of thin GaAs, InAs and InP nanowires. In each case, simulations performed using the classical Harrison potential afforded values of λ about an order of magnitude smaller than those obtained using more elaborate potentials (an Abell-Tersoff, as parameterized by Hammerschmidt et al for GaAs and InAs, and a potential of Vashishta type for InP). These results will be a warning to those wishing to use computer simulations to orient the development of quasi-one-dimensional systems as heat sinks or thermoelectric devices.     

Continuous variable feed rate: a novel method for improving infeed grinding processes

This paper presents a novel method for improving infeed grinding processes based on the application of continuous variable feed rate (CVFR). Nowadays, infeed cycle configuration is defined by selecting constant feed rates and stock removals for each consecutive stage, normally roughing, finishing, and a final spark-out, for the purpose of achieving required workpiece tolerances in a fixed time while avoiding process limitations and instabilities. CVFR leads to more efficient cycles without the difficulty of defining feed rate and stock removal values. To that end, CVFR has been implemented in a time-domain simulation of infeed grinding processes to analyze theoretically the influence of variation parameters in process forces, workpiece roughness, roundness and size tolerance, or dynamic behavior. Then, tests have been performed to validate the simulation approach, comparing CVFR cycles with equivalent conventional ones. Different types of downward variations for the feed rate have been applied, concluding that grinding processes can be improved with this method regarding productivity and workpiece geometrical and surface tolerances.     

Effects of particle size in wasted bread flour properties

Bread is wasted at different stages in the food value chain, mainly in industry and retail markets. Wasted bread can be milled into flour to be used in the elaboration of other food products. Milling can generate flours with different particle sizes that influence their properties. This study analysed the effect of particle size (200, 500 and 1000 μm) on the hydration, pasting and gel properties of flours elaborated with four different stale breads. Bread flours show a higher cold water absorption capacity and a lower oil absorption capacity than wheat flour. No differences in water absorption properties after heating were observed. The viscosity curves of bread flours presented lower values than wheat flour curves, and the gels obtained were weaker. Bread flour properties were not influenced by different particle sizes. Therefore, a less aggressive milling, with a lower energy cost, can generates flours with properties similar to finer flours.     

Modified Gutenberg–Richter Coefficient for Damage Evaluation in Reinforced Concrete Structures Subjected to Seismic Simulations on a Shaking Table

This paper presents analysis and discussion of the \(b\) - and ib-values calculated from the acoustic emission (AE) signals recorded during dynamic shake-table tests conducted on a reinforced concrete (RC) frame subjected to several uniaxial seismic simulations of increasing intensity until collapse. The intensity of shaking was controlled by the peak acceleration applied to the shake-table in each seismic simulation, and it ranged from 0.08 to 0.47 times the acceleration of gravity. The numerous spurious signals not related to concrete damage that inevitably contaminate AE measurements obtained from complex dynamic shake-table tests were properly filtered with an RMS filter and the use of guard sensors. Comparing the \(b\) - and ib-values calculated through the tests with the actual level of macro-cracking and damage observed during testing, it was concluded that the limit value of 0.05 proposed in previous research to determine the onset of macro-cracks should be revised in the case of earthquake-type dynamic loading. Finally, the \(b\) - and ib-values were compared with the damage endured by the RC frame evaluated both visually and quantitatively in terms of the inter-story drift index.