Medicinal plants have been used to treat various ailments of the poor population around the world;hence the interest among researchers to know the active ingredients of certain plants has being increased.The Calotropi...Medicinal plants have been used to treat various ailments of the poor population around the world;hence the interest among researchers to know the active ingredients of certain plants has being increased.The Calotropis procera(C.procera) is a plant original from Africa,commonly found in northeastern Brazil.It is well known for their pharmacological properties,since it produces large amounts of latex.The important role that medicinal plants play in folk medicine has led us to develop this article in order to review the major pharmacological activities of C. procera.展开更多
This research work was carried out with the aim of continuing to expand knowledge on the behaviour of AISI 304 stainless steel against solid particle erosion. In this particular case, the steel was subjected to the im...This research work was carried out with the aim of continuing to expand knowledge on the behaviour of AISI 304 stainless steel against solid particle erosion. In this particular case, the steel was subjected to the impact of alumina particles, which are hard abrasives with irregular and angular shapes. Different characterization techniques were applied to gain a better understanding of alumina. For instance, particle size distribution was obtained using the Analysette 28 Image Sizer and the particle size was between 300 - 400 µm. SEM and EDS analysis were used to know the morphology and chemical composition of both the abrasive particles and AISI 304 stainless steel. Additionally, mechanical properties values such as the hardness and Young’s modulus of AISI 304 steel were attained using a Berkovich indenter (model TTX-NHT, CSM Instruments). On the other hand, two tests were carried out for each impact angle used, 30˚, 45˚, 60˚ and 90˚, with a particle velocity of 24 ± 2 m/s and an abrasive flow rate of 63 ± 0.5 g/min, employing a test rig based on ASTM G76-95 standard. SEM images using two detectors, Backscattered Electron Detector (BED) and Low Electron Detector (LED), were employed to identify the wear mechanisms on the AISI 304 eroded surfaces at 30˚ and 90˚. Finally, the erosion rates of AISI 304 compared to those results reached by AISI 1018 steel and AISI 420 stainless steel tested under identical conditions in previous works.展开更多
Purpose: The primary aim of this paper is to design, create, and improve functional and artificial Bruch’s membranes (BM) using bioengineering techniques, which can be applied in the treatment of maculopathies by sup...Purpose: The primary aim of this paper is to design, create, and improve functional and artificial Bruch’s membranes (BM) using bioengineering techniques, which can be applied in the treatment of maculopathies by supporting the growth and maintenance of retinal pigment epithelium (RPE) cells, thereby potentially enabling subretinal implantation in patients. Methods: We fabricated by electrospinning ultrathin 3D nanofibrous membranes from Polycaprolactone (PCL), and different concentrations of gelatin (5%, 15% and 30%). ARPE-19 cells were seeded onto these artificial membranes. MTT assays were performed in order to evaluate ARPE-19 cell viability and cytotoxicity. IF assays were realized to observe the ARPE-19 cells onto each membrane. Ultrastructure of the modified Bruch’s membrane and ARPE-19 morphology after 25 days of culture were studied with transmission and scanning electron microscopy. To evaluate expression changes in markers of ARPE-19 (RPE65 and ZO-1) qRT-PCR assays were realized. Data from three independent experiments were pooled and expressed as the mean SD. A confidence level of P 0.05 was considered to be statistically significant. Results ARPE-19 cells grew on PCL/Gelatin membranes mainly in PCL/30% gelatin combination, which had not cytotoxic effect. RPE65/cytokeratin-18/ and actin-positive ARPE-19 cells formed a correctly orientated monolayer of polygonal cells with morphological polarity. The apical cell surfaces exhibited abundant protruding microfolds. Moreover, zones of polygonal border look as if ARPE-19 cells fused among, suggesting the presence of tight junctions. The expression of RPE65 and ZO-1 was unchanged. Conclusions: PCL/30% Gelatine membranes may imitate the natural BM to such extent that they support RPE-cells and exhibited RPE-like morphology. The engineering of a human RPE monolayer with these artificial BM, emulating the in vivo retina, arouse their potential subretinal implantation in patients with wet age-related macular degeneration (AMD) where there is a rupture of the Bruch’s membrane.展开更多
文摘Medicinal plants have been used to treat various ailments of the poor population around the world;hence the interest among researchers to know the active ingredients of certain plants has being increased.The Calotropis procera(C.procera) is a plant original from Africa,commonly found in northeastern Brazil.It is well known for their pharmacological properties,since it produces large amounts of latex.The important role that medicinal plants play in folk medicine has led us to develop this article in order to review the major pharmacological activities of C. procera.
文摘This research work was carried out with the aim of continuing to expand knowledge on the behaviour of AISI 304 stainless steel against solid particle erosion. In this particular case, the steel was subjected to the impact of alumina particles, which are hard abrasives with irregular and angular shapes. Different characterization techniques were applied to gain a better understanding of alumina. For instance, particle size distribution was obtained using the Analysette 28 Image Sizer and the particle size was between 300 - 400 µm. SEM and EDS analysis were used to know the morphology and chemical composition of both the abrasive particles and AISI 304 stainless steel. Additionally, mechanical properties values such as the hardness and Young’s modulus of AISI 304 steel were attained using a Berkovich indenter (model TTX-NHT, CSM Instruments). On the other hand, two tests were carried out for each impact angle used, 30˚, 45˚, 60˚ and 90˚, with a particle velocity of 24 ± 2 m/s and an abrasive flow rate of 63 ± 0.5 g/min, employing a test rig based on ASTM G76-95 standard. SEM images using two detectors, Backscattered Electron Detector (BED) and Low Electron Detector (LED), were employed to identify the wear mechanisms on the AISI 304 eroded surfaces at 30˚ and 90˚. Finally, the erosion rates of AISI 304 compared to those results reached by AISI 1018 steel and AISI 420 stainless steel tested under identical conditions in previous works.
文摘Purpose: The primary aim of this paper is to design, create, and improve functional and artificial Bruch’s membranes (BM) using bioengineering techniques, which can be applied in the treatment of maculopathies by supporting the growth and maintenance of retinal pigment epithelium (RPE) cells, thereby potentially enabling subretinal implantation in patients. Methods: We fabricated by electrospinning ultrathin 3D nanofibrous membranes from Polycaprolactone (PCL), and different concentrations of gelatin (5%, 15% and 30%). ARPE-19 cells were seeded onto these artificial membranes. MTT assays were performed in order to evaluate ARPE-19 cell viability and cytotoxicity. IF assays were realized to observe the ARPE-19 cells onto each membrane. Ultrastructure of the modified Bruch’s membrane and ARPE-19 morphology after 25 days of culture were studied with transmission and scanning electron microscopy. To evaluate expression changes in markers of ARPE-19 (RPE65 and ZO-1) qRT-PCR assays were realized. Data from three independent experiments were pooled and expressed as the mean SD. A confidence level of P 0.05 was considered to be statistically significant. Results ARPE-19 cells grew on PCL/Gelatin membranes mainly in PCL/30% gelatin combination, which had not cytotoxic effect. RPE65/cytokeratin-18/ and actin-positive ARPE-19 cells formed a correctly orientated monolayer of polygonal cells with morphological polarity. The apical cell surfaces exhibited abundant protruding microfolds. Moreover, zones of polygonal border look as if ARPE-19 cells fused among, suggesting the presence of tight junctions. The expression of RPE65 and ZO-1 was unchanged. Conclusions: PCL/30% Gelatine membranes may imitate the natural BM to such extent that they support RPE-cells and exhibited RPE-like morphology. The engineering of a human RPE monolayer with these artificial BM, emulating the in vivo retina, arouse their potential subretinal implantation in patients with wet age-related macular degeneration (AMD) where there is a rupture of the Bruch’s membrane.
