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Highresolution X-ray tomography can be used to measure the local mean curvature of fluid–fluid interfaces within the pores of opaque, permeable porous media. Thereof, the pore-scale capillary pressure can be estimated via the Young– Laplace equation. We critically review the aforementioned method by processing experimental data acquired with an X-ray cone-beam laboratory station and compare capillary pressure estimates with results of pore-scale numerical simulations. The method looks promising but is rather sensitive to the attainment of an equilibrium state for the fluid mixture and to the numerical calculation of curvature. Numerical simulation results provide evidence that dynamic effects result in a larger discrepancy between values of the capillary pressure computed from first principles (i.e., pressure difference across the interface) and from geometric considerations (i.e., curvature estimation and Young– Laplace equation).

The onset of post-operatory surgical-site infections is significantly correlated with the concentration of viable airborne bacteria that are shed from the surgical team or entering the operating room during door openings and are deposited directly on the patient's wound or on surgical instruments. The ultra-clean vertical laminar airflow ventilation system is often used to protect the main surgical area of operating rooms. The clean zone provided by the laminar airflow system is crowded with staff and furniture. As a result, some surgical instruments might remain outside the protected area. We use a numerical simulation to investigate the capability of a portable ultra-clean airflow unit to reduce the contamination of the principal instrumentation table by airborne bacteria, during a sham operation. The numerical model is thoroughly validated against the experimental data available for a test room. The portable air-cleaning device maintains sterile conditions on the principal instrumentation table over a range of flow rates of the general ventilation, although it induces higher levels of bacterial contamination in other zones of the room at the same time.

Mycotic keratitis is an extremely challenging pathology for clinicians in routine ophthalmological practice. This chapter focuses on the main related techniques in the literature. It highlights those which constitute the majority of surgical approaches: therapeutic penetrating keratoplasty, lamellar keratoplasty, conjunctival flap transposition, and cryotherapy. Therapeutic penetrating keratoplasty is the main surgical treatment reported for mycotic keratitis. The great challenge of the lamellar keratoplasty modality lies in the need to be sure of complete excision of the corneal tissue infiltrate, an indispensable prerequisite for therapeutic success of surgery for mycotic infections. In summary, surgical intervention is the only effective treatment for medically unresponsive mycotic keratitis. The best timing of surgical procedures remains uncertain but must precede deep corneal infection for decreasing subsequent surgical complications and preventing poor visual outcomes. Drug delivery systems based on nanotechnology approaches seem to be a promising adjunct modality in mycotic keratitis management, once it can improve corneal drug penetration, avoiding post-transplantation recurrence.

Resumo Neste relato, descrevemos um caso de Distrofia corneana de Schnyder que apresentou o desfecho de seu diagnostico baseado em achados caracteristicos na microscopia confocal, ferramenta que se aponta em destaque no universo oftalmologico.

X-ray radiography is used to sample the moving phase interface in a sequence of water–air and water–oil displacements. A bench-top X-ray CT scanner is used with a still sample continuously flooded with a positive-displacement type pump. A method is proposed to compute two-dimensional instantaneous saturation distributions from the radiographic sequence. Exploitation of the saturation profiles to drive a history-match procedure is demonstrated. This work shows that using simple radiographies of multiphase flows provides a real-time and low-cost method for tracking flooding processes through rock core samples and obtaining relative permeabilities thereof. Most important, due to the much higher frame rate attainable by taking radiographic images, compared to traditional X-ray CT scanning, flows with higher injection rates can be followed.

Oil-water relative permeability and capillary pressure of a water-wet digital core are computed using the finite-volume/volume of fluid method and mimicking traditional laboratory steady-state experiments carried out on a water saturated sample. Commercial software is used for immiscible multiphase fluid flow simulations, carried out on a low-cost multicore workstation, and the porescale data are upscaled to derive relative permeability and capillary pressure curves as function of water saturation. The digital sample is obtained by high resolution X-ray computed tomography scanning. [Received: March 13, 2013; Accepted: June 25, 2013]

The experimental investigation of flow through porous media is inherently difficult due to the lack of optical access. The recent developments in the fields of X-ray micro-tomography (micro-CT hereafter), digital sample reconstruction by image-processing techniques and fluid-dynamics simulation, together with the increasing power of super-computers, allow to carry out pore-scale simulations through digitally-reconstructed porous samples. The scientific relevance of pore-scale simulations lies in the possibility of upscaling the pore-level data, yielding volume-averaged quantities useful for practical purposes. One of the best-known examples of upscaling is the calculation of absolute and relative permeability of reservoir rocks. This contribution presents a complete work-flow for setting up pore-scale simulations, starting from the micro-CT of a (in general small) porous sample. Relevant applications are discussed in order to reveal the potential of the proposed methodology.

Resumo Neste relato, descrevemos um caso de Distrofia corneana de Schnyder que apresentou o desfecho de seu diagnóstico baseado em achados característicos na microscopia confocal, ferramenta que se aponta em destaque no universo oftalmológico.