Design and performance of ropes for climbing and sailing

Ropes are an important part of the equipment used by climbers, mountaineers, and sailors. On first inspection, most modern polymer ropes appear similar, and it might be assumed that their designs, construction, and properties are governed by the same requirements. In reality, the properties required of climbing ropes are dominated by the requirement that they effectively absorb and dissipate the energy of the falling climber, in a manner that it does not transmit more than a critical amount of force to his body. This requirement is met by the use of ropes with relatively low longitudinal stiffness. In contrast, most sailing ropes require high stiffness values to maximize their effectiveness and enable sailors to control sails and equipment precisely. These conflicting requirements led to the use of different classes of materials and different construction methods for the two sports. This paper reviews in detail the use of ropes, the properties required, manufacturing techniques and materials utilized, and the effect of service conditions on the performance of ropes. A survey of research that has been carried out in the field reveals what progress has been made in the development of these essential components and identifies where further work may yield benefits in the future

Residencia Sanitaria de la Seguridad Social La Paz

The full details of this project will be described in a later issue of this magazine. It includes the following: sanitary residence, maternity home, children's hospital, and outpatient's department. At present the first and last buildings are completed and in use. The sanitary residence is described below. This building incorporates the experience gained from other similar projects carried out by the State Health Insurance. This is perhaps a unique example in the western world of many health buildings, planned jointly, and built within a short space of time. The design has been inspired by three fundamental ideas, namely, airiness, flexibility and compactness in the space and volume distribution. The planform is a cross of unequal arms, where the central nucleus provides for the vertical circulation system. The organisation and distribution is most modern, and includes all recent advances that can be wished for in this type of building. The total built area, including galleries, boiler rooms, and tower, is 30.878 m² The number of beds is 855, which gives 36.11 m² per bed.<br><br>El complejo total, de próxima inauguración, que será publicado en un futuro número de INFORMES, comprenderá los siguientes cuerpos: Residencia Sanitaria, Maternidad, Traumatología, Hospital infantil y Ambulatorio. En la actualidad se hallan completamente terminados y en uso el primero y el último. Describimos a continuación la Residencia Sanitaria: En este edificio se han resumido las experiencias del conjunto de edificaciones realizadas por el Seguro de Enfermedad. Son un ejemplo, quizás único en Occidente, de construcciones hospitalarias ejecutadas bajo un mismo plan, en un lapso corto de tiempo, y dedicado al mismo fin. En la redacción del proyecto han presidido tres ideas fundamentales: claridad, flexibilidad y concentración, no sólo de espacio, sino también de volúmenes. La planta básica es una cruz de brazos desiguales con un núcleo central de circulaciones verticales. El organigrama, completísimo y con toda suerte de adelantos técnicos e instalaciones complementarias y auxiliares, abarca las máximas exigencias apetecibles en este tipo de edificios. La superficie total construida, incluidas galería, salas de calderas, plantas y torreón, es de 30.878,04 metros cuadrados, y el número real de camas, 855, lo que arroja una superficie por cama de 36,11 metros cuadrados

Fischer–Tropsch Synthesis Over Zr-Promoted Co/γ-Al2O3 Catalysts

Two Zr-modified alumina supports were synthetized containing the same amount of Zr but a different distribution of this modifier over the alumina surface. These supports, together with the unmodified alumina carrier, were used to prepare three cobalt-based catalysts which were characterized and tested under relevant Fischer–Tropsch conditions. The three catalysts presented very similar porosity and cobalt dispersion. The addition of Zr nor its distribution enhanced the catalyst reducibility. The catalyst activity was superior when using a carrier consisting of large ZrO2 islands over the alumina surface. The use of a carrier with a homogeneous Zr distribution had however, a detrimental effect. Moreover, a faster initial deactivation rate was observed for the Zr-promoted catalysts, fact that may explain this contradictory effect of Zr on activity. Finally, the addition of Zr showed a clear enhancement of the selectivity to long chain hydrocarbons and ethylene, especially when Zr was well dispersed

Fotosensibilización primaria por consumo de Ammi majus en bovinos: primer reporte en Argentina

Se describe un brote de fotosensibilización primaria en bovinos causado por el consumo de Ammi majus. Los animales manifestaron fotofobia, epífora, opacidad corneal bilateral y dermatitis en pezones, vulva y morro. Se descartó un origen secundario por daño hepático y se confirmó el diagnóstico por consumo voluntario de A. majus

No self-similar aggregates with sedimentation

Two-dimensional cluster-cluster aggregation is studied when clusters move both diffusively and sediment with a size dependent velocity. Sedimentation breaks the rotational symmetry and the ensuing clusters are not self-similar fractals: the mean cluster width perpendicular to the field direction grows faster than the height. The mean width exhibits power-law scaling with respect to the cluster size, ~ s^{l_x}, l_x = 0.61 +- 0.01, but the mean height does not. The clusters tend to become elongated in the sedimentation direction and the ratio of the single particle sedimentation velocity to single particle diffusivity controls the degree of orientation. These results are obtained using a simulation method, which becomes the more efficient the larger the moving clusters are.Comment: 10 pages, 10 figure

Alteration of the tree–soil microbial system triggers a feedback loop that boosts holm oak decline

In anthropic savanna ecosystems from the Iberian Peninsula (i.e. dehesa), complex interactions between climate change, pathogen outbreaks and human land use are presumed to be behind the observed increase in holm oak decline. These environmental disturbances alter the plant–soil microbial continuum, which can destabilize the ecological balance that sustains tree health. Yet, little is known about the underlying mechanisms, particularly the directions and nature of the causal–effect relationships between plants and soil microbial communities. In this study, we aimed to determine the role of plant–soil feedbacks in climate-induced holm oak decline in the Iberian dehesa. Using a gradient of holm oak health, we reconstructed key soil biogeochemical cycles mediated by soil microbial communities. We used quantitative microbial element cycling (QMEC), a functional gene-array-based high-throughput technique to assess microbial functional potential in carbon, nitrogen, phosphorus and sulphur cycling. The onset of holm oak decline was positively related to the increase in relative abundance of soil microbial functional genes associated with denitrification and phosphorus mineralization (i.e. nirS3, ppx and pqqC; parameter value: 0.21, 0.23 and 0.4; p < 0.05). Structural equation model (χ2 = 32.26, p-value = 0.73), moreover, showed a negative association between these functional genes and soil nutrient availability (i.e. mainly mineral nitrogen and phosphate). Particularly, the holm oak crown health was mainly determined by the abundance of phosphate (parameter value = 0.27; p-value < 0.05) and organic phosphorus (parameter value = −0.37; p-value < 0.5). Hence, we propose a potential tree–soil feedback loop, in which the decline of holm oak promotes changes in the soil environment that triggers changes in key microbial-mediated metabolic pathways related to the net loss of soil nitrogen and phosphorus mineral forms. The shortage of essential nutrients, in turn, affects the ability of the trees to withstand the environmental stressors to which they are exposed. Read the free Plain Language Summary for this article on the Journal blog. © 2023 The Authors. Functional Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.This research has been mainly funded by the Spanish Government through the IBERYCA project (CGL2017‐84723‐P), its associated FPI scholarship BES‐2014‐067971 (ME‐V), the SMARTSOIL (PID2020‐113244GB‐C21) and SMARTHEALTH (PID2020‐113244GA‐C22) projects (both funded by MCIN/AEI/10.13039/501100011033). It has been further supported by the BC3 María de Maeztu excellence accreditation (MDM‐2017‐0714; the Spanish Government), by the BERC 2018–2021 and by the UPV/EHU‐GV IT‐1648‐22 (from the Basque Government). Additionally, this research was further supported through the grant Holistic management practices, modelling and monitoring for European forest soils—HoliSoils (EU Horizon 2020 Grant Agreement No 101000289) and the ‘Juan de la Cierva programme’ (MV; IJCI‐2017‐34640; the Spanish Government). We acknowledge the Nutrilab‐URJC (Mostoles, Spain) laboratory services for the soil chemical analyses and SGIker of UPV/EHU (Leioa, Spain) for the technical and staff support for the high‐throughput quantitative‐PCR analysis. We also thank the private owners of the dehesas for facilitating our access to their properties. We are thankful to Celia López‐Carrasco Fernández and the ‘Consejería de Agricultura, Medioambiente y Desarrollo rural de la Junta de Castilla‐La Mancha’ for all the logistical support. The ‘Tree’ icon by Hey Rabbit illustrator, from thenounproject.com were used to design the Graphical abstract. Open Access funding provided by the Univer

Structure of laponite-styrene precursor dispersions for production of advanced polymer-clay nanocomposites

One method for production of polymer-clay nanocomposites involves dispersal of surface-modified clay in a polymerisable monomeric solvent, followed by fast in situ polymerisation. In order to tailor the properties of the final material we aim to control the dispersion state of the clay in the precursor solvent. Here, we study dispersions of surface-modified Laponite, a synthetic clay, in styrene via large-scale Monte-Carlo simulations and experimentally, using small angle X-ray and static light scattering. By tuning the effective interaction between simulated laponite particles we are able to reproduce the experimental scattering intensity patterns for this system, with good accuracy over a wide range of length scales. However, this agreement could only be obtained by introducing a permanent electrostatic dipole moment into the plane of each Laponite particle, which we explain in terms of the distribution of substituted metal atoms within each Laponite particle. This suggests that Laponite dispersions, and perhaps other clay suspensions, should display some of the structural characteristics of dipolar fluids. Our simulated structures show aggregation regimes ranging from networks of long chains to dense clusters of Laponite particles, and we also obtain some intriguing ‘globular’ clusters, similar to capsids. We see no indication of any ‘house-of-cards’ structures. The simulation that most closely matches experimental results indicates that gel-like networks are obtained in Laponite dispersions, which however appear optically clear and non-sedimenting over extended periods of time. This suggests it could be difficult to obtain truly isotropic equilibrium dispersion as a starting point for synthesis of advanced polymer-clay nanocomposites with controlled structures

Population inversion of a NAHS mixture adsorbed into a cylindrical pore

A cylindrical nanopore immersed in a non-additive hard sphere binary fluid is studied by means of integral equation theories and Monte Carlo simulations. It is found that at low and intermediate values of the bulk total number density the more concentrated bulk species is preferentially absorbed by the pore, as expected. However, further increments of the bulk number density lead to an abrupt population inversion in the confined fluid and an entropy driven prewetting transition at the outside wall of the pore. These phenomena are a function of the pore size, the non-additivity parameter, the bulk number density, and particles relative number fraction. We discuss our results in relation to the phase separation in the bulk.Comment: 7 pages, 8 Figure

Irreversible Aging Dynamics and Generic Phase Behavior of Aqueous Suspensions of Laponite

In this work we study the aging behavior of aqueous suspension of Laponite having 2.8 weight % concentration using rheological tools. At various salt concentration all the samples demonstrate orientational order when observed using crossed polarizers. In rheological experiments we observe inherent irreversibility in the aging dynamics which forces the system not to rejuvenate to the same state in the shear melting experiment carried out at a later date since preparation. The extensive rheological experiments carried out as a function of time elapsed since preparation demonstrate the self similar trend in the aging behavior irrespective of the concentration of salt. We observe that the exploration of the low energy states as a function of aging time is only kinetically affected by the presence of salt. We estimate that the energy barrier to attain the low energy states decreases linearly with increase in the concentration of salt. The observed superposition of all the elapsed time and the salt concentration dependent data suggests that the aging that occurs in low salt concentration systems over a very long period is qualitatively similar to the aging behavior observed in systems with high salt concentration over a shorter period.Comment: 27 pages, 8 figures. Langmuir, in pres