Structural control of the non-ionic surfactant alcohol ethoxylates (AEOs) on transport in natural soils.

Surfactants, after use, enter the environment through diffuse and point sources such as irrigation with treated and non-treated waste water and urban and industrial wastewater discharges. For the group of non-ionic synthetic surfactant alcohol ethoxylates (AEOs), most of the available information is restricted to the levels and fate in aquatic systems, whereas current knowledge of their behavior in soils is very limited. Here we characterize the behavior of different homologs (C12-C18) and ethoxymers (EO3, EO6, and EO8) of the AEOs through batch experiments and under unsaturated flow conditions during infiltration experiments. Experiments used two different agricultural soils from a region irrigated with reclaimed water (Guadalete River basin, SW Spain). In parallel, water flow and chemical transport were modelled using the HYDRUS-1D software package, calibrated using the infiltration experimental data. Estimates of water flow and reactive transport of all surfactants were in good agreement between infiltration experiments and simulations. The sorption process followed a Freundlich isotherm for most of the target compounds. A systematic comparison between sorption data obtained from batch and infiltration experiments revealed that the sorption coefficient (Kd) was generally lower in infiltration experiments, performed under environmental flow conditions, than in batch experiments in the absence of flow, whereas the exponent (ß) did not show significant differences. For the low clay and organic carbon content of the soils used, no clear dependence of Kd on them was observed. Our work thus highlights the need to use reactive transport parameterization inferred under realistic conditions to assess the risk associated with alcohol ethoxylates in subsurface environments.

Mapping the local viscosity of non-Newtonian fluids flowing through disordered porous structures.

Flow of non-Newtonian fluids through topologically complex structures is ubiquitous in most biological, industrial and environmental settings. The interplay between local hydrodynamics and the fluid's constitutive law determines the distribution of flow paths. Consequently the spatial heterogeneity of the viscous resistance controls mass and solute transport from the micron to the meter scale. Examples range from oil recovery and groundwater engineering to drug delivery, filters and catalysts. Here we present a new methodology to map the spatial variation of the local viscosity of a non-Newtonian fluid flowing through a complex pore geometry. We use high resolution image velocimetry to determine local shear rates. Knowing the local shear rate in combination with a separate measurement of the fluid's constitutive law allows to quantitatively map the local viscosity at the pore scale. Our experimental results-which closely match with three-dimensional numerical simulations-demonstrate that the exponential decay of the longitudinal velocity distributions, previously observed for Newtonian fluids, is a function of the spatial heterogeneity of the local viscosity. This work sheds light on the relationship between hydraulic properties and the viscosity at the pore scale, which is of fundamental importance for predicting transport properties, mixing, and chemical reactions in many porous systems.

Queratitis neurotrófica secundaria a malformación cerebral / Neurotrophic keratitis secondary to cerebral malformation

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Understanding hydraulic fracturing: a multi-scale problem.

Despite the impact that hydraulic fracturing has had on the energy sector, the physical mechanisms that control its efficiency and environmental impacts remain poorly understood in part because the length scales involved range from nanometres to kilometres. We characterize flow and transport in shale formations across and between these scales using integrated computational, theoretical and experimental efforts/methods. At the field scale, we use discrete fracture network modelling to simulate production of a hydraulically fractured well from a fracture network that is based on the site characterization of a shale gas reservoir. At the core scale, we use triaxial fracture experiments and a finite-discrete element model to study dynamic fracture/crack propagation in low permeability shale. We use lattice Boltzmann pore-scale simulations and microfluidic experiments in both synthetic and shale rock micromodels to study pore-scale flow and transport phenomena, including multi-phase flow and fluids mixing. A mechanistic description and integration of these multiple scales is required for accurate predictions of production and the eventual optimization of hydrocarbon extraction from unconventional reservoirs. Finally, we discuss the potential of CO2 as an alternative working fluid, both in fracturing and re-stimulating activities, beyond its environmental advantages.This article is part of the themed issue 'Energy and the subsurface'.

Asimetría pupilar secundaria a la administración local de bromuro de ipratropio / Pupilary asymmetry secondary to local administration of ipratropium bromide

La anisocoria se define como la diferencia de tamaño pupilar entre ambos ojos; su presencia en un paciente puede traducir desde procesos banales 1,2 a enfermedades graves que pueden poner en peligro su vida 3. Presentamos un caso de anisocoria producida por el efecto farmacológico del bromuro de ipratropio aplicado localmente sobre el ojo de un paciente no colaborador que estaba siendo tratado con este fármaco por un proceso espástico. La resolución espontánea del cuadro junto con una exploración tomográfica dentro de la normalidad dieron los indicios adecuados para su diagnóstico (AU)

Seudohipoparatiroidismo tipo Ia de presentación pediátrica / Pseudohypoparathyroidism type Ia presenting during childhood

El seudohipoparatiroidismo tipo la es una enfermedad infrecuente, de presentación familiar, caracterizada por resistencia renal a la acción de la parathormona, resultado de una actividad defectuosa de la proteína Gs, reguladora de la síntesis del AMPe. Se asocia con anomalías fenotípicas y con defectos en otras hormonas. Describimos un caso pediátrico de presentación esporádica asociado a hipotiroidismo, en el que la presencia de una calcificación en el talón izquierdo a los 4 años de edad fue la clave para orientar el diagnóstico. Se comenta la evolución y la respuesta al tratamiento (AU)

[Familial paroxysmal ataxia: a new case]. / Ataxia paroxística familiar: a propósito de un caso.

Over the last years several families affected of a clinical syndrome characterized by sudden ataxia, related to physical or mental stress, and lasting a few days have been described. Intercritical exploration is otherwise normal. We describe a new case which presents the clinical, laboratory and neuroradiological data characteristic of periodic familial ataxia. The patient is a 34 year old male who from his 23 has suffered three crisis of gait inestability, ataxia of trunk and limbs and spontaneous nystagmus in every direction, which increased in association with head movement. These episodes were always in relation with fatigue and stress and have decreased in severity. Mean duration of crisis has been 4 to 6 days. After starting treatment with acetazolamide there have no new crisis. In this case we have found no family history of the disease as it was the rule in previous description.

[Scheduled consultation in primary care. Analysis of several relevant factors]. / Consulta programada en atención primaria. Análisis de algunos factores implicados en su funcionamiento.

We carried out a longitudinal prospective study of 5179 appointments with 1782 patients, which generated 4483 scheduled consultation in a 10-month period, so as to evaluate changes in compliance, duration of visit and month of appointment, depending on the age and sex of the patient and the cause for consultation. There were no sex or age group differences in compliance, but there were differences depending on the cause for consultation (p less than 0.0001). Obesity, dyslipemia and family planning were the groups with the lowest compliance. A time longer than 15 minutes for each visit was spent in a greater number of women than of men (p less than 0.0001). The age group with the longest time interval per visit was the 25-34 years group. There was also a difference depending on the cause for consultation, which was also not randomly distributed throughout the surveyed months (p less than 0.05). It was concluded that the compliance with appointments was directly related with the perceived morbidity, that subprograms of attention to women take a longer time per visit, and that the month of appointment determines the distribution of the causes for consultation.

Dos nuevas localizaciones de transmisores de la enfermedad de Chagas en la Republica Mexicana. / Two new communities with transmissors of Chagas disease in the Mexican Republic

Se informa que en dos localidades, una perteneciente al estado de Queretaro y otra al de Guanajuato, se encontro Triatoma barberi. Se hace enfasis en el hallazgo debido a que estos dos estados aun no se habian senalado en la literatura medica con triatominos transmisores de enfermedad de Chagas. De esta manera se cubre todo el territorio nacional, en el cual existen una o mas poblaciones pertenecientes a cada uno de los estados con informes de hallazgos de triatominos infectados y no infectados en forma natural con Trypanosoma cruzi