Optimization of multilayer graphene-based gas sensors by ultraviolet photoactivation

Nitrogen dioxide (NO2) is a potential hazard to human health at low concentrations, below one part per million (ppm). NO2 can be monitored using gas sensors based on multi-layered graphene operating at ambient temperature. However, reliable detection of concentrations on the order of parts per million and lower is hindered by partial recovery and lack of reproducibility of the sensors after exposure. We show how to overcome these longstanding problems using ultraviolet (UV) light. When exposed to NO2, the sensor response is enhanced by 290 % − 550 % under a 275 nm wavelength light emitting diode irradiation. Furthermore, the sensor’s initial state is completely restored after exposure to the target gas. UV irradiation at 68 W/m2 reduces the NO2 detection limit to 30 parts per billion (ppb) at room temperature. We investigated sensor performance optimization for UV irradiation with different power densities and target gases, such as carbon oxide and ammonia. Improved sensitivity, recovery, and reproducibility of UV-assisted graphene-based gas sensors make them suitable for widespread environmental applications

Incorporation of the first and second heart fields and prospective fate of the straight heart tube via in vivo labeling of chicken embryos.

Recent discoveries of at least two heart fields and dynamic nature of cardiac development as well as controversies regarding the participation of heart fields in development of different heart structures led us to investigate the dynamics of incorporation of the first and second heart fields and prospective fate of the straight heart tube by labeling chicken embryos in vivo with the fluorescent lipophilic dye DiI. The cephalic and caudal limits of the anterior and posterior segments of the straight heart tube were labeled in two groups of embryos. Labels were tracked along the "C," "S," and "U" loops up to the tetracavitary or mature heart (n = 30 embryos/group; torsion and looping stage). To determine whether the atria and atrioventricular canal are derived from the first heart field the straight heart tube was cultured in vitro and immunodetection of Sox-9 and troponin I was performed to identify the mesenchymal and myocardial lineages respectively. Proliferating cell nuclear antigen (PCNA) immunodetection was used to determine the involvement of cell proliferation in heart tube development during torsion and looping. Embryological constitution of the straight heart tube and heart looping (C, S, and U) were not consistent with current descriptions. In fact, right ventricle precursors were absent in the straight heart tube derived from the first heart field. During torsion and looping, the cephalic segment of the straight heart tube gradually shifted into the heart tube until it was located at the myocardial interventricular septum in the tetracavitary heart. In contrast, the caudal segment of the straight heart tube was elongated and remodeled to become the first heart field derived left ventricle and the proximal part of the ventricular inlets. The ventricular outflows, right ventricle, distal part of the ventricular inlets, and atria developed from the second heart field

Entrapment Efficiency (EE) and Release Mechanism of Rhodamine B Encapsulated in a Mixture of Chia Seed Mucilage and Sodium Alginate

Chia seed mucilage is a polysaccharide capable of forming hydrogels with excellent water-binding capacity due to its physical and chemical properties and favorable characteristics for encapsulating and protecting valuable hydrophilic molecules in the food, pharmaceutical, and cosmetic industries. This research aimed to show that mixtures of chia seed mucilage and sodium alginate used as wall materials to encapsulate hydrophilic molecules are suitable. We analyzed the relationship between the mucilage–alginate solution’s properties and the capsules obtained; we quantified the entrapment efficiency (EE%) and the release of rhodamine B; and we proposed a method to follow the rhodamine B release using confocal laser scanning microscopy (CLSM). We found that more viscous solutions are obtained when the mucilage concentration increases, making it difficult to produce capsules with less sphericity. The best entrapment efficiency was found when the proportion of the polymers was close to 1:1, based both on the properties of the capsules obtained and on the characterization of the release kinetics of rhodamine B; the analysis performed by fitting rhodamine B release data to theoretical models describe the diffusion process. Our results show that the use of chia seed mucilage as a wall material to trap and retain hydrophilic molecules is convenient