Se presentan los contenidos más relevantes de algunas asignaturas de cuatro carreras de ingeniería de la Universidad Nacional de Colombia, Sede Bogotá, y se establecen relaciones con los contenidos de las dos asignaturas básicas de física, ofrecidas en todas las carreras de ingeniería. También se presentan los resultados preliminares de consultas realizadas a profesores y estudiantes de ingeniería sobre estas relaciones. Los datos que surgen del estudio pueden ser fundamentales para los estudiantes y para los profesores de las asignaturas de física en las carreras de ingeniería.
The objective was to model the survival of Bacillus cereus LSPQ 2872 and Escherichia coli O157:H7 exposed to gamma radiation, using Tsallis entropy and the Monte performed with a noise level of 0.05 to assess the sensitivity of the Tsallis entropy-based models (dose-proportional effect, linear-quadratic dose-effect relationship, and and Escherichia coli exposed to radiation. For Bacillus cereus, the dose-proportional effect and linear-quadratic dose-effect models showed similar lethal doses (0.935 and efficacy. In Escherichia coli, the dose-proportional effect and linear-quadratic dose-effect models also showed similar lethal doses (0.716 and 0.745 kGy), and the Sotolongo et al. model showed a lower lethal dose (0.319 kGy), indicating greater efficacy. Tsallis entropy-based models are suitable for describing membrane behavior and biochemical changes in bacteria exposed to gamma radiation.
In this paper, the energy eigenvalues of the helium atom and the helium-like ions up to Z=5 in dense plasma are investigated with screened interaction potentials using Debye-Huckel model and exponential cosine screened Coulomb potential using variational Monte Carlo method. The calculations which are carried out in this paper are based on using trial wave functions with different asymptotic behaviors, classified as polynomial correlation, exponential decreasing, and exponential increasing functions. Furthermore, the low-lying excited states of the helium atom were investigated under the same model potentials using trial wave functions for the lowest four excited states, corresponding to the configurations 1s2s and 1s2p. Interesting results are obtained in comparison with results obtained by using other trial wave functions.
The primary objective of this study is to reconstruct the energy spectrum from three linear accelerators (LINACs) using experimental measurements of the percentage depth dose (PDD) curve. The experimentally obtained percentage depth dose curves were used to solve the Fredholm integral equation. The photon beam spectra are related to radiation doses through a Fredholm integral equation, utilizing the generalized simulated annealing optimization method. The resulting spectrum was used to simulate an irradiation reference condition as recommended by TRS-398. The Monte Carlo codes PENELOPE and TOPAS were employed to create the simulation scenario under reference conditions (10 x 10 cm2 field size, 100 cm SSD, and 30 x 30 x 30 cm3 water phantom) for 6 MeV photon beams. The calculated spectra from the three LINACs demonstrated a remarkable level of concordance, achieving up to 99% agreement. The validation of the reconstructed spectrum was carried out by comparing it with the PDD and beam profile curves, revealing a highly favorable correspondence in their behavior. A comprehensive analysis compared the experimentally acquired PDDs with those simulated using the reconstructed spectrum. Parameters such as the entrance dose and TPR20/10 were derived from the PDD curves for evaluation. Upon conducting a thorough comparison of these parameters with the experimental dataset, noticeable deviations of 10% (entrance dose), and 3% (TPR20/10). Beam profile comparisons across field size dimensions revealed differences ranging from 0.5% to 5.3%. The present study encompassed the reconstruction of the photon beam spectrum originating from LINACs, revealing a noteworthy level of agreement among them. The validation of the Fredholm integral equation by utilizing two simulation codes, as facilitated by the analysis of the PDD and beam profile curves, revealed substantial disparities within the region leading up to the build-up point. This reconstructed spectrum holds considerable potential for simulation scenarios within radiotherapy applications. This significance is particularly underscored by the challenges associated with acquiring comprehensive data from manufacturers of LINACs, which impedes access to crucial information regarding the constituents of these accelerators.
Phosgene (COCl2), a highly toxic industrial and chemical warfare agent, exerts its pathological effects through poorly understood interactions with heme-containing proteins. The essence of this study lies in elucidating the atomic-level mechanisms of phosgene-heme binding, with the primary objective of identifying the dominant coordination mode and its implications for toxicity and therapeutic intervention. This study employs density functional theory (DFT) at the B3LYP-D3/6-311+G(d,p) level to systematically investigate phosgene adsorption on heme (C20H12FeN4), revealing two distinct binding modes: Fe(II)-O and Fe(II)-Cl coordination. Our calculations demonstrate that the Fe-Cl configuration is energetically favored (BE = -4.38 eV/ - 100.9 kcal/mol at 2.96 A & ring;) over Fe-O binding (1.59 eV/36.6 kcal/mol at 1.55 A & ring;), a preference validated by comparison with EXAFS data (Fe-Cl similar to 2.90-3.10 A & ring;) and experimental optical spectra. The identified angular dependence shows catastrophic binding energy reduction (-8.83 eV) beyond 80 degrees rotation, while solvent effects (water, ethanol) weaken Fe-O binding by similar to 25%, correlating with observed humidity-dependent toxicity attenuation. Electric field modulation (0.01 au) reduces Fe-Cl binding energy by 10%, suggesting novel detoxification strategies. UV-Vis spectral simulations reproduce the characteristic Soret band shifts (triangle lambda = 22 nm) observed in phosgene-exposed hemoglobin, establishing a computational framework for predicting toxicological outcomes. These findings provide: (1) the first atomic-level explanation of phosgene's heme-binding selectivity, (2) quantitative structure-toxicity relationships for antidote development, and (3) a validated methodology for studying related toxic gas-biomolecule interactions. The work bridges computational chemistry and biomedical defense, offering mechanistic insights to guide therapeutic interventions against chemical threats.
It is modeled a quantum memory unit as a two qubits interacting with an external bath. The transfer of information from one qubit into the other can be optimally achieved if there exist a good entanglement between them. The two qubits are allocated in a spatial separation d. It is proposed a phenomenological ansatz where their entanglement in presence of noise depends on d. The above opens new possibilities for further operative technologies of quantum memories.
Relevant contents of several engineering courses corresponding to four engineering programs in the Bogota campus of Universidad Nacional de Colombia are presented, in order to establish significant relations with contents of the basic physics courses offered for all engineering careers. Initial outcomes of consultations made to engineering students and teachers are also presented. This information may be fundamental for students and teachers of these physics courses.
This study presents the preparation and characterization of cobalt nanoscale particles, focusing on several of their physical properties. Cobalt nanostructures were synthesized employing a Q-switched Nd: laser with a fundamental wavelength of 1064 nm, a pulse duration of 10 ns, and a repetition rate of 1 Hz. Laser ablation energies of 200 and 400 mJ, along with varying pulse counts of 100, 200, and 300 per energy setting, were used for synthesis. The measured physical properties include optical absorbance, absorption coefficient, energy gap, refractive index, and and 3.53 eV, were observed, showing a slight increase with the total number of pulses, with minimal influence from the higher total number of pulses.
This study aimed to optimize the scan parameters of the Siemens Somatom Scope CT simulator to ensure optimal image quality for the detection of brain tumors. To achieve this, measurements were performed using the Catphan CTP 503 phantom, evaluating metrics such as the contrast-to-noise ratio (CNR), low-contrast visibility (LCV), signal-to-noise ratio (SNR), noise level, and uniformity index (UI). The optimization process involved adjusting scan parameters such as kilovoltage (kV), tube current (mA), and the automatic exposure control system (CareDose4D). The results showed that the optimized protocol (Protocol 2) achieved the highest CNR values-61.41 for polymethylpentene (PMP) and 47.9 for low-density polyethylene (LDPE)-as well as the best LCV and an SNR of 31.2. In addition, it exhibited the lowest noise level (0.3 %) and the best uniformity index (0.03). These findings suggest that Protocol 2 may be an effective tool for improving the accuracy of brain structure delineation and other anatomical regions, thereby enhancing radiotherapy treatment planning.
En este trabajo, presentamos un estudio de la respuesta de la impedancia longitudinal de muestras de los vidrios metálicos Fe70Nb10B20 y [(Fe50Co50)75B20Si5]96Nb4 mediante el uso de la resonancia de un solenoide pequeño. Las medidas de impedancia longitudinal en función de la frecuencia se realizaron en el rango de 0 < f < 30 MHz para campos magnéticos de HDC = 0,5, 10, 20, 30 y 40 Oe a temperatura ambiente. Las curvas obtenidas presentan incrementos en la amplitud de los picos de impedancia en torno a la región de resonancia del solenoide. Con base en esto, se propone un circuito equivalente y un ajuste polinómico generado por inteligencia artificial (IA) para modelar la respuesta de impedancia de estos sistemas.
In this research, binderless paper-based composite boards were fabricated from waste papers and then assessed experimentally for their suitability as ceiling materials in building construction. During the process, waste newspaper paste (WNP) and waste writing paper paste (WWP) were prepared and used at varying percentages (0, 30, 50, 70, and 100%) on weight basis to develop the ceiling samples. Three samples were prepared for each mix design, dried to constant weight, and characterized in terms of physical properties, thermal responses, and strength behaviors. The results showed maximum bulk density (587.0 kgm(-3)), thermal conductivity (0.0835 Wm(-1)K(-1)), thermal diffusivity (10.56 x10(-8) m(2)s(-1)), flexural strength (1.318 N/mm(2)), and internal bond strength (0.214 N/mm(2)) at 100.0% loading of the WWP. Though nailability remained 100.0% notwithstanding the composite mixes, the samples recorded the highest thickness swelling (26.89%), void fraction (49.92%), and specific heat capacity (1429 Jkg(-1)K(-1)) as the proportion of the WNP increased to 100.0%. Further, it was found that these WNP-WWP samples could outperform conventional ceilings such as plaster of Paris, asbestos, and KalsiCeil. The undertaking described herein can ensure reduction in production time since no adhesive is required, thus benefiting both the environment and economy while availing the building sector with cost-effective and sustainable ceilings for building construction. The knowledge from this research could help in solving the disposal problems associated with waste papers and also tackling hampering of sustainable housing development due to high cost of building construction materials.
This work evaluates the electrochemical performance of carbon-coated LiFePO4(LiFePO4/C) using a plant extract of Caroxylon Imbricatum Forssk via a green synthesis route. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and cyclic voltammetry to investigate the phase, crystalline structure, morphology and electrochemical performance. Both samples, LiFePO(4)and LiFePO4/C, exhibited an olivine LiFePO(4)structure and the obtained particle sizes were in the nanoscale. The effects of the carbon coating improved the electrochemical performances of carbon-coated LiFePO(4)via enhancing rate capability and electronic conductivity.
In this work, we present a study of the longitudinal impedance response of samples of the metallic glasses Fe70Nb10B20 and [(Fe50Co50)75B(20)Si(5)](96)Nb-4 by using the resonance of a small solenoid. Longitudinal impedance measurements as a function of frequency were performed in the range 0 < f < 30 MHz for DC magnetic fields H-DC = 0, 5, 10, 20, 30 and 40 Oe at room temperature. The curves obtained show increases in the amplitude of the impedance peaks around the solenoid resonance region. Based on this, an equivalent circuit and a polynomial adjustment generated by artificial intelligence (AI) are proposed to model the impedance response of these systems.
The branching ratios and total decay widths of the gauge boson Z ' have been calculated in the version of the 3-3-1 Model with heavy leptons. We analyze the total decay width, the decay rates and determine the most likely channels to occur in order to identify the most relevant final events.
Nanotechnology-based medicine has driven significant progress, providing revolutionary solutions for the diagnosis and treatment of diseases, although challenges remain, such as ensuring safety and scalability. This systematic review examines the latest applications of nanotechnology in personalized medicine, focusing on its ability to develop treatments tailored to the specific characteristics of each individual. Nanoparticles stand out for enhancing the accuracy of drug delivery, reducing side effects, particularly in cancer therapies. Additionally, technologies such as biosensors and nanoscale imaging devices improve diagnostics, increasing success rates in clinical settings. In the field of tissue regeneration and engineering, nanomaterials, by replicating the extracellular matrix, promote cell regeneration and the creation of synthetic organs. Nevertheless, concerns persist regarding the biocompatibility of these materials, as their interaction with biological systems has yet to be fully understood, raising questions about potential future impacts. The production and quality control of nanomaterials are costly and technically complex, hindering their accessibility and scalability. Furthermore, the lack of defined regulations delays the implementation of these innovations. This review not only aims to consolidate key achievements but also to promote the dissemination of knowledge in Latin America, where access to specialized scientific data is limited, affecting students and researchers. With more studies on biological interactions and process standardization, nanotechnology could become a transformative tool in medicine, improving treatments and enhancing public health in the region.
Theoretically, we analyze the effect of electron-phonon interaction in the dynamics of an electron trapped in a benzene-shaped quantum dot-molecule. The molecule consists of six small quantum dots coupled locally to a phonon bath. The tight-binding model is used to write the model Hamiltonian and to derive the set of equations of motion of different types of benzene quantum dot-molecules. The time-dependent model has a numerically exact solution, producing rich dynamics. The values of time-dependent occupations strongly depend on the electron-phonon coupling. A notable result of the present work is that one can tune the energy levels of quantum dots, the quantum contacts energy levels, and the benzene quantum dot-molecule configuration to enhance or diminish the heat flow between electrons and phonons in molecular junctions. This study contributes to the dynamic and expanding field of quantum dot molecular systems, providing insights for broader technological applications.
La medicina nanotecnológica ha propiciado progresos importantes, proporcionando soluciones revolucionarias para el diagnóstico y tratamiento de enfermedades, aunque aún existen retos, como asegurar su seguridad y escalabilidad. Esta revisión metódica examina las últimas aplicaciones de la nanotecnología en la medicina personalizada, centrándose en su habilidad para elaborar tratamientos de acuerdo con las particularidades de cada individuo. Las nanopartículas se distinguen por incrementar la exactitud en la administración de medicamentos, disminuyendo los efectos adversos, particularmente en terapias para el cáncer. Adicionalmente, tecnologías tales como biosensores y dispositivos de imagen a nanoescala mejoran los diagnósticos, aumentando las oportunidades de éxito en el ámbito clínico. En el ámbito de la regeneración e ingeniería de tejidos, los nanomateriales, al replicar la matriz extracelular, promueven la regeneración celular y la creación de órganos sintéticos. No obstante, todavía persisten preocupaciones respecto a la biocompatibilidad de estos materiales, dado que aún no se ha entendido completamente su interacción con los sistemas biológicos ni los posibles impactos en el futuro. La producción y supervisión de la calidad de los nanomateriales son costosas y técnicamente complicadas, lo que obstaculiza su accesibilidad y escalabilidad. Además, la ausencia de normativas definidas demora la puesta en marcha de estas innovaciones. Esta revisión no solo aspira a reunir éxitos fundamentales, sino también a impulsar la propagación del saber en América Latina, donde el acceso a datos científicos especializados es restringido, impactando a alumnos e investigadores. Con más estudios sobre interacciones biológicas y normalización de procesos, la nanotecnología podría establecerse como un instrumento de cambio en la medicina, mejorando los tratamientos y potenciando la salud pública en la región.
This article analyzes the propagation of electromagnetic waves in multilayer systems using the transfer matrix method (TMM). Some fundamental optical properties, which include transmittance and reflectance, are examined in dielectric materials and photonic crystals; the influence on radiation propagation associated to some system variables, including the number of layers, their thickness, and stratified deposition, is analyzed. Our main results include the identification of transmission and reflection bands, the influence of the system geometry and periodicity on the optical efficiency, and the viability of the TMM, which can be accomplished by comparing our results with experimental data. In addition, sets of optimal configurations of multilayer systems are presented that show how transmittance is maximized within the optical spectrum. These findings highlight the versatility of the TMM in order to design coatings of high transmittance (or reflectance) and advanced photonic devices, which have several applications, including the areas of photovoltaic cells and optical sensors.
Positive-parity states of 120–130Xe isotopes were calculated based on the interacting boson model 1 (IBM-1), Semi-Experimental Formula (SEF), and New Empirical Equation (NEE). The calculated results are compared to experimental energy levels, specifically GS, β, and γ bands, in addition to reduced B(E2) transition probabilities. IBM-1, SEF, and NEE accurately represent the comparable energy levels of the GS, γ, and β bands for 120–130Xe. However, IBM-1 exhibits greater deviations at higher energy levels. The present calculations replicate the experimental results of 120–130Xe. The potential energy surface (PES) is a nuclear property that determines the ultimate form of nuclei. PES plotting reveals that the 120–130Xe isotopes are deformed and have a γ–unstable limit.
John Joseph Hopfield began his career studying excitons in condensed matter physics, but his most important contributions were in the physics of computation and information, including his 1982 work on neural networks. Geoffrey Hinton, known as the “godfather” of artificial intelligence, laid the foundations for deep neural networks and developed the “backpropagation” method in 1986. These advances, along with Hopfield networks and the “Boltzmann machine”, constitute the beginning of artificial intelligence. David Baker is a pioneer in the design and prediction of three-dimensional protein structures, while Demis Hassabis has applied artificial intelligence to neuroscience. John Michael Jumper has investigated the use of AI to simulate protein folding and dynamics. Hopfield and Hinton received the 2024 Nobel Prize in Physics, and Baker, Hassabis and Jumper received the Nobel Prize in Chemistry, sparking debates on interdisciplinarity and academic degrees in the sciences.
