Laser Floating Zone: General Overview Focusing on the Oxyorthosilicates Growth

This chapter reviews the laser floating zone (LFZ) technique, also known as the laser-heated pedestal growth (LHPG), focusing on the recently produced rare-earth-doped oxyorthosilicate fibers. LFZ has been revealed as a suitable prototyping technique since high-quality crystals can be developed in short time with low consumption of precursor materials in a crucible-free processing that ensures to practically avoid by-products. Moreover, additional advantages are the possibility to treat and melt highly refractory materials together with the easy way for tailoring the final microstructural characteristics and this way the macroscopic physical properties. Thus, refractory rare-earth (RE) doped oxyorthosilicates following the formula RE2SiO5 have been recently produced by the LFZ technique for tuning laser emission parameters. The oxyorthosilicates have high chemical stability and allow incorporation of many rare-earth ions yielding different applications, such as laser host materials, gamma ray detectors or scintillators, environmental barrier coatings (EBCs) and waveguides, among others. Thus, different kinds of oxyorthosilicates were produced by the LFZ technique, and the detailed effects of the main processing parameters on crystal’s characteristics are discussed in this chapter

Skyglow inside your eyes: intraocular scattering and artificial brightness of the night sky

The visual perception of the natural night sky in many places of the world is strongly disturbed by anthropogenic light. Part of this artificial light is scattered in the atmosphere and propagates towards the observer, adding to the natural brightness and producing a light polluted sky. However, atmospheric scattering is not the only mechanism contributing to increase the visual skyglow. The rich and diverse biological media forming the human eye also scatter light very efficiently and contribute, in some cases to a big extent, to the total sky brightness detected by the retinal photoreceptors. In this paper we quantify this effect and assess its relevance when the eye pupil is illuminated by light sources within the visual field. Our results show that intraocular scattering constitutes a significant part of the perceived sky brightness at short distances from streetlights. These results provide quantitative support to the everyday experience that substantial gains in naked-eye star limiting magnitudes can be achieved by blocking the direct light from the lamps that reaches the eye pupil

Microfluidic devices manufacturing with a stereolithographic printer for biological applications

Stereolithographic printers have revolutionized many manufacturing processes with their capacity to easily produce highly detailed structures. In the field of microfluidics, this technique avoids the use of complex steps and equipment of the conventional technologies. The potential of low force stereolithography technology is analysed for the first time using a Form 3B printer and seven printing resins through the fabrication of microchannels and pillars. Manufacturing performance of internal and superficial channels and pillars is studied for the seven printing resins in different configurations. A complete characterization of printed structures is carried out by optical, confocal and SEM microscopy, and EDX analysis. Internal channels with unobstructed lumen are obtained for diameters and angles greater than 500 μm and 60°, respectively. Outward and inward superficial channels in the range of hundreds of microns can be fabricated with an accurate profile, printing them with a perpendicular orientation respect to the base, allowing a proper uncured resin evacuation. Outward channels are replicated by soft lithography using polydimethylsiloxane. Clear, Model and Tough resins show a good behaviour to be used as master, but Amber and Dental resins present a poor topology transference from the master to the replica. According to the needs of devices used for biological and biomedical research, transparency as well as superficial biocompatibility of some resins is evaluated. Human umbilical vein endothelial cells (HUVEC) adhesion is confirmed on Amber, Dental and Clear resins, but these cells were only able to grow and progress as a cell culture over the Amber resin. Therefore, Amber showed an adequate biocompatibility, in terms of cell adhesion and growth for HUVECAuthors gratefully thank contracts AEI RTI2018-097063-B-100, AEI/FEDER, UE; ED431B 2020/29; ED431E 2018/08 and ED481D-2021-019, Consellería de Educación Xunta de Galicia/FEDER e Estructuración Xunta de Galicia, IN607A2019-02 and Sociedad española de cardiología y Fundación español del corazón, SEC/FEC-INV-BAS 20/013S

Internal Microchannel Manufacturing Using Stereolithographic 3D Printing

Internal channels are one of the most interesting structures to implement in microfluidics devices. Unfortunately, the optical technologies typically used in microfluidics, such as photolithography or reactive ion etching, are unable to generate these structures by only allowing surface structuring. Stereolithographic 3D printing has emerged as a very promising technology in internal microchannel manufacturing, by allowing a layer-by-layer structuring in volume performed by a laser that photopolymerises a liquid resin. Recent advances in laser technologies have reached resolutions of tens of micrometres. The high resolution of this type of printer, which a priori would allow the fabrication of channels of the same dimensions, may pose a problem by impeding the evacuation of uncured resin. In this chapter, the compromise between size and resin evacuation will be evaluated to find the optimal diameter range in which unobstructed and accurate microchannels can be obtained

Sol-Gel Glass Coating Synthesis for Different Applications: Active Gradient-Index Materials, Microlens Arrays and Biocompatible Channels

The intent of this chapter is to review the use of sol-gel processing of silica and silica-titania optical coatings in recent research by the authors in three different areas: the synthesis of active gradient-index (GRIN) materials by multilayer deposition of erbium- and ytterbium-doped silica-titania films, the improvement of the optical and morphological qualities of microlens arrays fabricated by laser ablation and the functionalization of polydimethylsiloxane (PDMS) channel preclinical devices. Through the use of sol-gel, layers with specific properties can be produced. In this regard, undoped and erbium- and ytterbium-doped SiO2-TiO2 films have been produced and characterized using atomic force microscopy (surface topography evaluation) and spectral ellipsometry (determination of optical constants, thickness and porosity of the films). In a second application, a silica sol has been synthesized to coat microlens arrays fabricated by laser ablation. The deposited layer reduces the surface roughness of the microlens array, which yields the improvement of the contrast and the homogeneity of the foci. Finally, PDMS channels fabricated with laser technologies and soft-lithography methods are coated with a sol-gel-derived silica film to avoid the degradation of the material with organic solvents, and their biocompatibility is studied

Fabrication of a Cell Electrostimulator Using Pulse Laser Deposition and Laser Selective Thin Film Removal

In this work, we present a laser-based process for fabricating a cell electrostimulator. The fabrication methodology comprises two laser processes: a pulse laser deposition (PLD) of an aluminum thin film on soda-lime glass and a laser-based selectively removal of the thin film. The laser set-up for PLD consist of Nd:YVO4 Rofin Power line 20E (1064 nm wavelength, 20 ns pulse width) focused by a lens of 160 mm focal length inside a vacuum chamber to strike a target of the deposited material. The same laser is used for selectively removing the thin film but focused by a lens of 100 mm focal length. The geometry design is made in CAD-like software. Before microfabrication, a thin aluminum layer (1 μm thickness) is deposited on soda-lime glass using the PLD method. In order to assemble the device, the electrical stimulator is placed between two polycarbonate sheets of 1.5 mm thickness. To prevent any contact with the electric circuit, a thin silicate glass (100 μm) is placed over the electrostimulator. Simulations were performed using ANSYS Maxwell software, verifying that the induced electrical field achieves the minimum for cell stimulation

Bioelectronics-on-a-chip for cardio myoblast proliferation enhancement using electric field stimulation

Background: Cardio myoblast generation from conventional approaches is laborious and time-consuming. We present a bioelectronics on-a-chip for stimulating cells cardio myoblast proliferation during culture. Method: The bioelectronics chip fabrication methodology involves two different process. In the first step, an aluminum layer of 200 nm is deposited over a soda-lime glass substrate using physical vapor deposition and selectively removed using a Q-switched Nd:YVO4 laser to create the electric tracks. To perform the experiments, we developed a biochip composed of a cell culture chamber fabricated with polydimethylsiloxane (PDMS) with a glass coverslip or a cell culture dish placed over the electric circuit tracks. By using such a glass cover slip or cell culture dish we avoid any toxic reactions caused by electrodes in the culture or may be degraded by electrochemical reactions with the cell medium, which is crucial to determine the effective cell-device coupling. Results: The chip was used to study the effect of electric field stimulation of Rat ventricular cardiomyoblasts cells (H9c2). Results shows a remarkable increase in the number of H9c2 cells for the stimulated samples, where after 72 h the cell density double the cell density of control samples. Conclusions: Cell proliferation of Rat ventricular cardiomyoblasts cells (H9c2) using the bioelectronics-on-a-chip was enhanced upon the electrical stimulation. The dependence on the geometrical characteristics of the electric circuit on the peak value and homogeneity of the electric field generated are analyzed and proper parameters to ensure a homogeneous electric field at the cell culture chamber are obtained. It can also be observed a high dependence of the electric field on the geometry of the electrostimulator circuit tracks and envisage the potential applications on electrophysiology studies, monitoring and modulate cellular behavior through the application of electric fieldsThis work was partially supported by Mineco through the projects FIS 2015–71933-REDT and RTI 2018–097063-B-I00, Consellería de Educación Program for Development of a Strategic Grouping in Materials – AeMAT Grant No. ED431E2018/08, Xunta de Galicia ref. ED431B2017/64. Xunta de Galicia, Spain, under Galician Programme for Research Innovation and Growth 2011–2015 (I2C Plan)S

Unha enxeñeira ou científica en cada cole

Póster presentado na V XORNADA UNIVERSITARIA GALEGA EN XÉNERO. TRANSFORMANDO DENDE A UNIVERSIDADE. Vigo, 7 Xullo 2017Nesta comunicación, presentamos o proxecto Unha enxeñeira ou científica en cada cole organizado pola Oficina de Igualdade de Xénero da Universidade de Santiago de Compostela (USC) en colaboración co Concello de Santiago de Compostela. Esta iniciativa pretende incentivar a presenza de rapazas en carreiras relacionadas coas disciplinas STEM (ciencia, enxeñería, tecnoloxía e matemáticas), mediante actividades didácticas nos centros educativos que rachen cos estereotipos sexistas da nosa sociedade. A actividade didáctica consistiu na realización de dezanove obradoiros, dirixidos a nenas e nenos de 5º ou 6º de primaria e realizados nos meses de setembro e outubro de 2016. Os obradoiros foron impartidos por profesoras ou investigadoras da USC e do Centro de Supercomputación de Galicia (CESGA) para crear referentes femininos e incentivar a presenza de rapazas no ámbito científico tecnolóxico. Ademais, estes obradoiros amosaron a relación da ciencia e da tecnoloxía coa nosa vida cotiá e serviron para achegar ao alumnado a estas disciplinas dun xeito lúdicoConcello de Santiago de Compostel

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat