Even at low concentrations, poly-aromatic hydrocarbons found in soot have substantial health implications. Soot deposits have been reported and studied using FTIR and Raman spectroscopy. Using a CO₂ photolysis laser, the samples were obtained via infrared multiphoton dissociation (IRMPD) of vinyl bromide (VBr, C₂H₃Br) molecules. The solid deposit formed in the IRMPD of VBr when a relatively high fluence of the order of 204J.cm⁻² was analyzed by FTIR, and it was discovered that the majority of its composition is aromatic and aliphatic hydrocarbons. Significant fullerene-type carbonaceous soot particles are also found, which could correspond to C₆₀ and C₇₀ or other carbonaceous agglomerates of a higher order; however, the disappearance of this fullerene on Raman spectra cast doubt on this explanation. Our samples Raman spectroscopy has been compared to Tamor and Vassells research, which may indicate that they have a lesser degree of hardness and density than these authors results, indicating a larger hydrogen content in our samples. The optical gap has been calculated, yielding a very limited range of values ranging only between 1.0 and 1.2eV, resulting in a crystalline size of 0.58 to 1.12nm.

This paper presents the design and development of a reconfigurable circular array antenna capable of producing ten distinct radiation beams, intended for wireless systems in the sub-6 GHz frequency band. The antenna structure is based on four pentagon-shaped radiating elements arranged symmetrically around a central circular patch, which is excited through a coaxial feed. These radiating elements are linked by four circular segments, ensuring mutual coupling for effective operation. A systematic dimensional analysis has been conducted to optimize electromagnetic performance, resulting in a compact and efficient architecture. The beam reconfiguration is achieved through the control of four PIN diodes, which allow the main radiation beam to switch among ten different orientations in the azimuth plane. Specifically, the antenna supports eight directional states, oriented at 45° intervals, and two additional bidirectional states covering opposite directions. A prototype has been fabricated and experimentally validated, confirming the steering capability of ±40° in both the XZ and YZ planes. Performance evaluation shows a maximum gain of 9.29 dBi and efficiency levels ranging from 91% to 97%. Bandwidth varies across states, with 9.72% for S1–S7, 7.45% for S2–S8, and 4.61% for S9–S10. Overall, the proposed design demonstrates optimized bandwidth, gain, efficiency, and complete azimuthal coverage.

The optical frequency comb generator (OFCG) is an attractive optical reference source for various applications such as optical frequency metrology, precision spectroscopy and telecommunications [D.J. Jones, S.A. Diddams, J.K. Ranka, A. Stentz, R.S. Windeler, S.T. Cundiff, Science 288, 635–639 (2000); T. Udem, R. Holzwarth, T.W. Hänsch, Nature 416, 233–237 (2002); T.W. Hänsch, J. Alnis, P. Fendel, M. Fischer, C. Gohle, M. Herrmann, R. Holzwarth, N. Kolachevsky, Th. Udem, M. Zimmermann, Philos. Trans. R. Soc. A 363, 2155–2163 (2005)]. In particular, the OFCG can be used as source for absolute frequency measurement, providing a precise ruler for length metrology. In the present work we describe the results of absolute frequency measurements of primary wavelength standards at 633 nm on the sixth components, d, e, f, g, h and i of the R(127) 11-5 hyperfine transition of the ¹²⁷I₂ molecule, at the Spanish Centre of Metrology, CEM. The values obtained with a femtosecond frequency comb (FC1500, Menlo Systems) at CEM are compared with the values recommended by the Consultative Committee for Length (CCL) [T.J. Quinn, Metrologia 40, 103–133 (2003)]. This determination was made by beat frequency method between a femtosecond laser comb and an iodine-stabilized He-Ne laser. The difference between the mean frequency of the sixth components of the standard laser and those of CCL recommended values for the same components was found to be 6.557 kHz.

The global development of LED lighting in all applications for both public and indoor lighting establishes a very important lever for reducing the carbon impact by significantly reducing energy consumption. Smart lighting will therefore constitute an essential lever in the smart city of tomorrow. The latter is more sustainable and less energy-intensive than other light sources, contributing towards the Sustainable Development Goals set forth by the United Nations (SDGs 7 and 11). With its ease of integration, ergonomics, lightness, and high quality of light, this innovative light source has two major qualities: its energy efficiency and its long service life. However, poor thermal management has catastrophic effects on these two essential criteria. This necessarily requires optimizing thermal management and heat sinks. In some cases, thermal models and simulations can lead to considerable calculation times because they implement many parameters. This work therefore aims to reduce the number of these simulations by applying the method of experimental designs (Taguchi) and analysis of variance (ANOVA) to simulations intended to optimize the dissipation of LED luminaires. We applied the method to a simple finned heat sink model for a unit input power and then to a concrete case of a high-power LED. The control parameters and their respective contributions in the proposed model were studied. The ANOVA results corroborated the conclusions of the Taguchi method, demonstrating a strong agreement between these analytical methods, in which the temperature was adjusted by identifying optimal combinations of parameters. The fields of application relevant to this study include both indoor lighting (false ceiling) and confined spaces with severe sealing constraints such as car headlights or the optical blocks of urban luminaires.