RESUMEN
Hydrophobic surfaces have a wide range of applications, such as water harvesting, self-cleaning, and anti-biofouling. However, traditional methods of achieving hydrophobicity often involve the use of toxic materials such as fluoropolymers. This study aims to create controllable wettability surfaces with a three-dimensional geometry using a laser base powder bed fusion (PBF) process with commercially pure titanium (CP-Ti) and silicone oil as non-toxic materials. The optimal PBF process parameters for fabricating micropillar structures, which are critical for obtaining the surface roughness necessary for achieving hydrophobic properties, were investigated experimentally. After fabricating the micropillar structures using PBF, their surface energy was reduced by treatment with silicone oil. Silicone oil provides a low-surface-energy coating that contributes to the water-repellent nature of hydrophobic surfaces. The wettability of the treated CP-Ti surfaces was evaluated based on the diameter of the pillars and the space between them. The structure with the optimal diameter and spacing of micropillars exhibited a high contact angle (156.15°). A pronounced petal effect (sliding angle of 25.9°) was achieved because of the morphology of the pillars, indicating the controllability of wetting. The micropillar diameter, spacing, and silicone oil played crucial roles in determining the water contact and sliding angle, which are key metrics for surface wettability.
RESUMEN
In the directed energy deposition (DED) process, significant empirical testing is required to select the optimal process parameters. In this study, single-track experiments were conducted using laser power and scan speed as parameters in the DED process for titanium alloys. The results of the experiment confirmed that the deposited surface color appeared differently depending on the process parameters. Cross-sectional view, hardness, microstructure, and component analyses were performed according to the color data, and a color suitable for additive manufacturing was selected. Random forest (RF) and support vector machine multi-classification models were constructed by collecting surface color data from a titanium alloy deposited on a single track; the accuracies of the multi-classification models were compared. Validation experiments were performed under conditions that each model predicted differently. According to the results of the validation experiments, the RF multi-classification model was the most accurate.
RESUMEN
Astrocytes are the most abundant cells in the brain, playing vital roles in neuronal survival, growth, and function. Understanding the mechanism(s) regulating astrocyte proliferation will have important implications in brain development, response to injury, and tumorigenesis. Cyclin B1 is well known to be a critical regulator of mitotic entry via its interaction with cyclin-dependent kinase 1. In rat astrocytes, we now show that the mRNA binding protein cytoplasmic polyadenylation element binding protein 1 (CPEB1) is associated with cyclin B1 mRNA and that this interaction is enriched at the centrosome. In addition, if growth-arrested astrocytes are stimulated to divide, CPEB1 is phosphorylated and cyclin B1 mRNA is polyadenylated, both hallmarks of CPEB1 activation, resulting in an increase in cyclin B1 protein. CPEB1 binding to mRNA initially inhibits translation; therefore, removing CPEB1 from mRNA should result in an increase in translation due to derepression. Indeed, when we either knocked down CPEB1 protein with siRNA or sequestered it from endogenous mRNA by expressing RNA containing multiple CPEB1 binding sites, cyclin B1 protein was increased and cell proliferation was stimulated. Our data suggest a mechanism wherein CPEB1 is bound and represses cyclin B1 mRNA translation until a signal to proliferate phosphorylates CPEB1, resulting in an increase in cyclin B1 protein and progression into mitosis. Our results demonstrate for the first time a role for CPEB1 in regulating cell proliferation in the brain.