RESUMO
BACKGROUND: The Erector Spinae Plane (ESP) block is a recent development in the field of regional anaesthesia and has been increasingly explored for abdominal surgeries to reduce opioid use and improve pain control. Colorectal cancer is the commonest cancer in multi-ethnic Singapore and requires surgery for curative treatment. ESP is a promising alternative in colorectal surgeries, but few studies have evaluated its efficacy in such surgeries. Therefore, this study aims to evaluate the use of ESP blocks in laparoscopic colorectal surgeries to establish its safety and efficacy in this field. METHODS: A prospective two-armed interventional cohort study comparing T8-T10 ESP blocks with conventional multimodal intravenous analgesia for laparoscopic colectomies was conducted in a single institution in Singapore. The decision for doing an ESP block versus conventional multimodal intravenous analgesia was made by a consensus between the attending surgeon and anesthesiologist. Outcomes measured were total intra-operative opioid consumption, post-operative pain control and patient outcome. Post-operative pain control was measured by pain score, analgesia use, and amount of opioids consumed. Patient outcome was determined by presence of ileus. RESULTS: A total of 146 patients were included, of which 30 patients received an ESP block. Overall, the ESP group had a significantly lower median opioid usage both intra-operatively and post-operatively (p = 0.031). Fewer patients required patient-controlled analgesia and rescue analgesia post-operatively for pain control (p < 0.001) amongst the ESP group. Pain scores were similar and post-operative ileus was absent in both groups. Multivariate analysis found that the ESP block had an independent effect on reducing intra-opioid consumption (p = 0.014). Multivariate analysis of post-operative opioid use and pain scores did not yield statistically significant results. CONCLUSIONS: The ESP block was an effective alternative regional anaesthesia for colorectal surgery that reduced intra-operative and post-operative opioid use while attaining satisfactory pain control.
Assuntos
Neoplasias Colorretais , Laparoscopia , Bloqueio Nervoso , Humanos , Analgésicos Opioides/uso terapêutico , Anestésicos Locais , Dor Pós-Operatória/etiologia , Dor Pós-Operatória/prevenção & controle , Bloqueio Nervoso/métodos , Estudos Prospectivos , Estudos de Coortes , Analgesia Controlada pelo Paciente , Colectomia , Neoplasias Colorretais/cirurgia , Ultrassonografia de Intervenção/métodosRESUMO
ZnO is an interesting material for photoactive and optoelectronic devices because of the wide range of available nanostructures and advantageous semiconducting properties. However, a significant drawback of ZnO is the low stability in high or low pH solutions. This has limited the development of ZnO core-shell materials for use in Z-scheme systems or photovoltaics, where any secondary phase is produced using chemical solution processing at low or high pH. Here, we show a simple process to produce an organic capping layer of 3-aminopropyltriethoxysilane that can successfully stabilize nanostructured ZnO for processing below pH 1. We demonstrate that this process can be used to produce a ZnO-BiFeO3 (BFO) core-shell structure by a sol-gel process. Using a range of physical and analytical techniques, we show that BFO is highly crystalline and produces a conformal coating with a thickness of 2.5 nm. X-ray photoelectron spectroscopy and X-ray diffraction confirm the phase and expected chemical composition of BFO. Finally we are able to demonstrate that diodes produced using the ZnO-BFO core-shell structure have improved performance with a rectification ratio at ±3 V of 2800 because of the reduction in reverse current typically associated with surface recombination on ZnO. Our process opens a route to producing a range of hitherto prohibited ZnO core-shell structures that may have applications ranging from photovoltaic devices to core-shell photocatalysts.
RESUMO
This paper reports for the first time the use of perovskite bismuth ferrite (BiFeO3 or BFO) on ZnO-based solid state solar cells using only chemical solution methods for materials synthesis. As ZnO has poor chemical stability in acidic and corrosive environments, a buffer method using aminosilane ((3-aminopropyltriethoxysilane or H2N(CH2)3Si(OC2H5)3)) coating was used to provide a protective coating on the ZnO nanorods. The aminosilane layer was removed after BFO coating. The solid state solar cells, sensitized by N719, used CuSCN as the hole conductor and were tested under 100 mW cm(-2), AM 1.5G simulated sunlight. The photovoltaic performance showed current density improvement from 0.64 mA cm(-2) to 1.4 mA cm(-2) and efficiencies from 0.1% to 0.38% when comparing between ZnO and ZnO/BFO solar cells. The observed ca. 400% improved performance is shown to result from BFO's role as an electron blocking layer.
RESUMO
ZnO is widely used as an n-type semiconductor in various solar cell structures; including dye-sensitized, organic, hybrid and solid-state solar cells. Here, we review advances in ZnO-based solar cell applications, looking at the influence of morphology, as well as the effect of different materials and sensitizers. ZnO morphologies play an important role in changing the surface area and charge transport properties, affecting the performance of the solar cells. External quantum efficiencies using purely ZnO as the active material has generally been below 3% with some dye-sensitized solar cells using liquid electrolytes above 5%. Sensitizers such as organic and inorganic dyes, quantum dots and hole conductors have been shown to influence cell efficiency by improving the absorption or providing improved charge transport. The combination of ZnO with other nanomaterials such as, TiO2, SiO2 and ZrO2 in core-shell structures or buffer layers creates improved electron transport by controlling recombination at interfaces and increasing stability of the device. The highest reported efficiencies to date were from combinational structures at 7.07% for ZnO nanosheets with TiO2 nanoparticulate coating and 7% for ZnO core-TiO2 shell structures.