Effects of a thermal inversion experiment on STEM students learning and application of damped harmonic motion

There are diverse teaching methodologies to promote both collaborative and individual work in undergraduate physics courses. However, few educational studies seek to understand how students learn and apply new knowledge through open-ended activities that require mathematical modeling and experimentation focused on environmental problems. In this work, we propose a novel home experiment to simulate the dynamics of a particulate under temperature inversion and model it as damped harmonic motion. Twenty six first year students enrolled in STEM majors answered six qualitative questions after designing and developing the experiment. These questions helped analyze the students epistemological beliefs about their learning process of physics topics and its applications. Results showed that this type of open-ended experiments could facilitate the students understanding of physics phenomena. In addition, this experiment showed that it could help physics professors to promote students epistemological development by giving their students the opportunity to search for different sources of knowledge and becoming self-learners instead of looking at the professor as the epistemological authority. At the end, students described this activity as a positive experience that helped them realize alternative ways to apply physics topics in different contexts of their environment.Comment: 23 pages, 5 figure

Enhanced plasmonic behavior of bimetallic (Ag-Au) multilayered spheres

In this article we study the plasmonic behavior of some stable, highly biocompatible bimetallic metal-dielectric-metal (MDM) and double concentric nanoshell (DCN) structures. By simply switching the material of the inner structure from Au to Ag, the intensity of their surface plasmon resonance could be increased in the optical transparency region of the human tissues up to 20 and 60 percent for the MDM and DCN, respectively, while the biocompatibility is retained. The obtained results indicate that these novel structures could be highly suitable for surface enhanced Raman scattering and photothermal cancer therapy

Pulsational frequencies of the eclipsing delta-Scuti star HD 172189

The eclipsing delta-Scuti star HD 172189 is a probable member of the open cluster IC 4756 and a promising candidate target for the CoRoT mission. The detection of pulsation modes is the first step in the asteroseismological study of the star. Further, the calculation of the orbital parameters of the binary system allows us to make a dynamical determination of the mass of the star, which works as an important constraint to test and calibrate the asteroseismological models. From a detailed frequency analysis of 210 hours of photometric data of HD 172189 obtained from the STEPHI XIII campaign we have identified six pulsation frequencies with a confidence level of 99% and a seventh with a 65% confidence level in the range between 100-300 uHz. In addiction, three eclipses were observed during the campaign, allowing us to improve the determination of the orbital period of the system.Comment: 6 pages, 7 figure

Kinetics of color center formation in silica irradiated with swift heavy ions: Thresholding and formation efficiency

We have determined the cross-section σ for color center generation under single Br ion impacts on amorphous SiO2. The evolution of the cross-sections, σ(E) and σ(Se), show an initial flat stage that we associate to atomic collision mechanisms. Above a certain threshold value (Se > 2 keV/nm), roughly coinciding with that reported for the onset of macroscopic disorder (compaction), σ shows a marked increase due to electronic processes. In this regime, a energetic cost of around 7.5 keV is necessary to create a non bridging oxygen hole center-E′ (NBOHC/E′) pair, whatever the input energy. The data appear consistent with a non-radiative decay of self-trapped excitons

Obtención y evaluación del semen de capibara Hydrochoerus hydrochaeris

RESUMEN Objetivo. Determinar las características del semen y la morfometría de los espermatozoides del Capibara (Hydrochoerus hydrochaeris). Materiales y métodos. Se utilizaron 10 machos con peso entre 21-45 kg, los cuales fueron restringidos y anestesiados. El semen se obtuvo mediante electroeyaculación y se determinó el color, volumen, pH, motilidad en masa, motilidad individual, viabilidad, concentración y morfología. Se realizaron además mediciones de la cabeza y la cola de los espermatozoides. Resultados. Se obtuvo semen en el 100% (10/10) de los animales. El mayor número de eyaculaciones (80%; 8/10), se obtuvo con un voltaje máximo de 6V. El color fue blanco, de aspecto lechoso, los valores promedio fueron volumen 135.5±93.56 μl, pH 8.14±0.38, motilidad masal 32.60±13.46%, motilidad individual 34±19.81%, viabilidad 51.3±19.42%, concentración espermática 127±59.01x106 espermatozoides/mL y morfología 51.3±19.42 espermatozoides normales. La longitud de la cabeza fue 5.41±0.7 μm, el ancho de la cabeza 3.77±0.5 μm y área de la cabeza 75.66±20.6 μm2. La longitud de la cola fue 27.9±11.3 μm. Conclusiones. La obtención del semen fue satisfactoria mediante electroeyaculación, sin presentar notables diferencias en las características del semen y morfología de los espermatozoides con otros roedores silvestres de menor tamaño, aunque se observó una alta variabilidad de estas características entre los animales muestreados posiblemente por la heterogeneidad de los animales experimentales

Partitioning of trace elements in a entrained flow IGCC plant: Influence of selected operational conditions

The partitioning of trace elements and the influence of the feed conditions (50:50 coal/pet-coke feed blend and limestone addition) was investigated in this study. To this end feed fuel, fly ash and slag samples were collected under different operational conditions at the 335 MW Puertollano IGCC power plant (Spain) and subsequently analysed. The partitioning of elements in this IGCC plant may be summarised as follows: (a) high volatile elements (70–>99% in gas phase): Hg, Br, I, Cl and S; (b) moderately volatile elements (up to 40% in gas phase and 60% in fly ash): As, Sb, Se, B, F, Cd, Tl, Zn and Sn; (c) elements with high condensation potential: (>90% in fly ash): Pb, Ge, Ga and Bi; (d) elements enriched similarly in fly ash and slag 30–60% in fly ash: Cu, W, (P), Mo, Ni and Na; and (e) low volatile elements (>70% in slag): Cs, Rb, Co, K, Cr, V, Nb, Be, Hf, Ta, Fe, U, Ti, Al, Si, Y, Sr, Th, Zr, Mg, Ba, Mn, REEs, Ca and Li. The volatility of As, Sb, and Tl and the slagging of S, B, Cl, Cd and low volatile elements are highly influenced by the fuel geochemistry and limestone dosages, respectively

Process design for the manufacturing of soft X-ray gratings in single-crystal diamond by high-energy heavy-ion irradiation

Artículo con 9 figurasThis paper describes in detail a novel manufacturing process for optical gratings suitable for use in the UV and soft X-ray regimes in a single-crystal diamond substrate based on highly focused swift heavy-ion irradiation. This type of grating is extensively used in light source facilities such as synchrotrons or free electron lasers, with ever-increasing demands in terms of thermal loads, depending on beamline operational parameters and architecture. The process proposed in this paper may be a future alternative to current manufacturing techniques, providing the advantage of being applicable to single-crystal diamond substrates, with their unique properties in terms of heat conductivity and radiation hardness. The paper summarizes the physical principle used for the grating patterns produced by swift heavy-ion irradiation and provides full details for the manufacturing process for a specific grating configuration, inspired in one of the beamlines at the ALBA synchrotron light source, while stressing the most challenging points for a potential implementation. Preliminary proof-of-concept experimental results are presented, showing the practical implementation of the methodology proposed herein.The authors acknowledge funding support by the following projects: PID2020-112770RB-C22 from the Spanish Ministry of Science and Innovation, TechnoFusión (III)-CM (S2018/EMT-4437) from Comunidad de Madrid (cofinanced by ERDF and ESF), agreement between Community of Madrid and Universidad Autónoma de Madrid (item “Excellence of University Professorate”). M.L.C. acknowledges financial support from the research project “Captacion de Talento UAM” Ref: #541D300 supervised by the Vice-Chancellor of Research of Universidad Autónoma de Madrid (UAM). LOREA beamline at ALBA is a project co-funded by the European Regional Development Fund (ERDF) within the Framework of the Smart Growth Operative Programme 2014-2020. The authors acknowledge the support from The Centro de Microanálisis de Materiales (CMAM)—Universidad Autónoma de Madrid, for the beam time proposal (demonstration of a grating profile for soft X-rays in diamond via ion lithography) with code IuB-005/21, and its technical staff for their contribution to the operation of the accelerator. We also acknowledge P. Olivero for very useful comments on the manuscript draf

Formation of hollow silver nanoparticles under irradiation with ultrashort laser pulses

9 pags., 5 figs.We have studied the formation of cavities in spherical silver nanoparticles embedded in silica, irradiated with fs laser pulses that produce an intense electronic excitation. Experimentally determined aspect ratio, i.e. the ratio between the cavity and nanoparticle size, for hollow structures formed under different irradiation conditions shows a very good agreement with values obtained by means of atomistic simulations. According to the predictions of the atomistic model, one can produce at will hollow silver nanoparticles with cavities of tailored dimensions, having an accurate control. Hence, laser irradiation can be used to control and design the optical response by tuning the localized surface plasmon resonances of the hollow nanoparticles.This work was partially funded by the regional government of Madrid through the TechnoFusion (III)-CM (S2018/EMT-4437) program, co-financed with Structural Funds (ERDF and ESF) and by the Projects PID2019-105325RB-C32 (Radiafus-5), PID2019-105156GB-I00, PID2021- 123228NB-I00 and PDC2022-133788-I00, funded by the Ministerio de Ciencia e Innovación of Spain. This work has also been partially funded by the Eurofusion consortium (EH150531176). JK was supported by the Beatriz Galindo Program (BEAGAL18/00130) from the Ministerio de Educación y Formación Profesional of Spain. This work was partially funded by Comunidad de Madrid through the Convenio Plurianual with Universidad Politécnica de Madrid in its line of action Apoyo a la realización de proyectos de I + D para investigadores Beatriz Galindo, within the framework of V PRICIT (V Plan Regional de Investigación Científica e Innovación Tecnológica). AP and FJV were supported by FONDECYT grant 3190123. MLC was supported by the research project “Captación de Talento UAM” Ref: #541D300 supervised by the Vice-Chancellor of Research of Universidad Autónoma de Madrid (UAM). The research leading to this result has been supported by the RADIATE project under the Grant Agreement 824096 from the EU Research and Innovation programme HORIZON 2020

Proyecto de gestión de redes en BioCen

BioCen is a scientific institution made up of several production units that are dedicated to different lines in the Cuban biotechnology and pharmaceutical universe. To guarantee the security and management of the information generated in the institution, and to reduce the impact of IT risk, it has a set of tools, procedures and strategies, collected in a network management project that is updated every year. The project includes everything related to the configuration, structure, control and monitoring, both of the data network, the process network, and the Wi-Fi network; in addition to the organization of services, servers, and the systems that comprise them. This paper presents the management tools used in BioCen for the control and monitoring of the services provided on the network, its internal and external traffic; as well as the detection of incidents. Examples of monitoring and control are shown with the management tools that are applied in some functional areas, as well as the design of the local BioCen network. Finally, the tests carried out on the network system, internal audits, statistical analysis of services and response to incidents are addressed.BioCen es una institución científica integrada por varias unidades productivas que se dedican a diferentes líneas en el universo biotecnológico y farmacéutico cubano. Para garantizar la seguridad y gestión de la información que se genera en la institución y minimizar el impacto de los riesgos asociados a fallas en la infraestructura, se cuenta con un conjunto de herramientas, procedimientos y estrategias, recogidas en un proyecto de gestión de redes que se actualiza todos los años. El proyecto recoge lo relacionado a la configuración, estructura, control y monitoreo, tanto de la red de datos, la de proceso, como de la wifi; además de la organización de los servicios, servidores, y los sistemas que los conforman. En este trabajo se presentan las herramientas de gestión utilizadas en BioCen para el control y monitoreo de los servicios que se prestan en la red, el tráfico interno y externo de la misma; así como la detección de incidentes. Se muestran ejemplos de monitoreo y control con las herramientas de gestión que se aplican en algunas áreas funcionales, así como el diseño de la red local de BioCen. Finalmente se abordan las pruebas realizadas al sistema de red, las auditorías internas, el análisis estadístico de los servicios y la respuesta a incidentes