Search

In-situ nuclear magnetic resonance (NMR) core flooding system has enabled researchers to monitor several rock properties such as porosity, pore size distribution, and fluid saturation along the tested samples with high resolutions and under reservoir conditions. However, spatially resolved rock strength/mechanical property alteration coupled to fluid migration/substitution remains poorly characterized. To this end, Fiber Bragg Grating (FBG) multiplex sensors were integrated with NMR core flooding system to monitor rock strength changes, or generally speaking, to observe hydro-mechanical-chemical coupling mechanisms during core flooding tests. In this study, we present a novel approach on how to conduct core flooding experiments, while simultaneously monitoring NMR and FBG strain response of the tested limestone plug. The NMR cell was modified to integrate FBG technology without impeding the NMR signal and core flooding high pressure/temperature capacity. A high spatial resolution optical fiber was attached onto the sample radial surface. The results show the successful association of NMR and FBG sensors to track any change at each stage of brine injection. The FBG is capable of measuring the rock strain variations induced by rock-fluid interactions during brine injection, allowing it to capture the fluid front location along with the sample and at a faster rate than the NMR.

The origin of the light emission from nanosilicon systems, such as crystalline silicon nanoparticles (Si-NPs), has been an intensively debated issue, with seemingly contradicting literature results pointing to different mechanisms. Here, the origin of the photoluminescence (PL) from application-grade Si–SiO2 core–shell nanoparticles with different sizes and synthesized with the industrially scalable high-yield nonthermal silane plasma method has been elucidated. It is found that the commonly observed PL from these Si-NPs originates, in general, from two processes: recombination within the nanoparticle silicon core and recombination within the oxide shell. The photon energies of both emissions increase with decreasing nanoparticle size. Importantly, a nanoparticle size dependence of the relative contribution of the two processes to the overall PL is established. For large (small) Si-NPs, the luminescence is dominated by the core (oxide-shell) emission. Interestingly, the transition between these two regime limits occurs within an extremely narrow nanoparticle size range (∼0.5 nm). This critical transition, in combination with the close photon energies of the two emission components, is responsible for the common observation of only a single unstructured PL band for Si-NPs and for the seemingly conflicting assignments of the origin of this luminescence found in the literature for apparently similar Si-NPs. [ABSTRACT FROM AUTHOR]

Introduction Most pediatric urethral injuries are a result of pelvic fracture after high-impact blunt trauma, mainly due to motor vehicle accidents. The management of urethral injuries depends on if the rupture is complete or partial as well as the timing of surgical intervention. Presentation of cases Three male children with urethral trauma caused by motor vehicles accidents are presented in this article. Preoperative suprapubic catheterization was initially carried out in all patients. Each patient then received one of three different techniques during the deferred time to surgical intervention: anterior sagittal transanorectal approach (ASTRA) for end-to-end urethral anastomosis, perineal approach for urethroplasty using buccal mucosa, and urethroplasty with preputial skin flap. The three techniques were successfully performed. Discussion In the initial management suprapubic cystostomy has been a good solution in urgent situations. Deferred urethroplasty is the procedure of choice for the definite treatment of posterior urethral distraction defects. The anterior sagittal transanorectal approach provides excellent exposure of the posterior urethra and retrovesicular region, and allows the surgeon to perform dissection under direct vision. Conclusion It’s very important for the pediatric urologist to be familiar with the different techniques available in order to choose the best approach for each particular patient. [ABSTRACT FROM AUTHOR]

Self-organizing nanopatterns can enable economically competitive, industrially applicable light-harvesting platforms for thin-film solar cells. In this work, we present transparent solar cell substrates having quasi-periodic uniaxial nanowrinkle patterns with high optical haze values. The self-organized nanowrinkle template is created by controlled heat-shrinking of metal-deposited pre-stretched polystyrene sheets. A scalable UV-nanoimprinting method is used to transfer the nanopatterns to glass substrates on which single-junction hydrogenated amorphous silicon p-i-n solar cells are subsequently fabricated. The structural and optical analyses of the solar cell show that the nanowrinkle pattern is replicated throughout the solar cell structure leading to enhanced absorption of light. The efficient broadband light-trapping in the nanowrinkle solar cells results in very high 18.2 mA/cm 2 short-circuit current density and 9.5% energy-conversion efficiency, which respectively are 35.8% and 39.7% higher than the values obtained in flat-substrate solar cells. The cost- and time-efficient technique introduces a promising new approach to customizable light-management strategies in thin-film solar cells. [ABSTRACT FROM AUTHOR]

Copyright of Análise is the property of EDIPUCRS - Editora Universitaria da PUCRS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)