UAM Iztapalapa

This paper is focused on the development of the notions of canonical and canonoid transformations within the framework of Hamiltonian Mechanics on locally conformal symplectic manifolds. Both, time-independent and time-dependent dynamics are considered. Noether-like theorems relating one-parameter groups of transformations with canonical and noncanonical symmetries, are formulated, proved as well as illustrated with elementary examples.

Comparative studies report inconsistent peptide yields, bioactivities, and sensory outcomes for Alcalase across substrates, creating uncertainty about when it should be favored over other proteases. This study mapped research on hydrolysis of food proteins with Alcalase to quantify scientific output, organize thematic trends, and identify gaps relevant to peptide-based functional foods. A bibliometric analysis of Web of Science records (2004–2024) was performed in R (bibliometrix), using co-occurrence networks, temporal overlays, and conceptual mapping. The dataset comprised 203 documents from 78 sources, exhibiting a 10.3% annual growth rate and a 36.9% international co-authorship rate. Themes clustered around antioxidant and angiotensin-converting enzyme (ACE) inhibitory peptides, particularly in dairy and marine matrices, are supported by workflows combining Alcalase hydrolysis with size-guided ultrafiltration, RP-HPLC (Reverse Phase High-Performance Liquid Chromatography), and, more recently, in silico analyses and encapsulation studies. Recurrent limitations were identified: heterogeneous hydrolysates and uneven reporting that hinder sequence–activity correlations, gastrointestinal degradation and bitterness affecting applicability, and scale-up and purification choices influencing feasibility. The mapping clarified where Alcalase enables bioactive peptide generation and highlighted practical priorities, including protocol standardization and enzyme benchmarking, the integration of peptidomics and machine learning with targeted assays, and formulation-focused validation (encapsulation, stability, and delivery) to bridge in vitro activity to real-world use. These directions support the production of reproducible, application-ready peptide ingredients.

Thermogravimetry coupled to Fourier-transform infrared spectroscopy (TGA/FTIR) was used to analyze the evolved gases from pyrolysis of four different lignocellulosic fibers (abaca, hemp, henequen, and coconut) that contain variable percentages of cellulose, hemicellulose and lignin. TGA results revealed that although the fibers exhibited different thermal stabilities (henequen had the highest decomposition temperature while coconut reported the lowest), the thermal decomposition pattern was similar as all samples displayed two degradation stages. By comparing representative spectra of the evolved gases at each stage for all-natural fibers, it was observed that during the first emission, the released gases were different and varied depending on fiber type. In contrast, during the second emission, similar spectra were obtained for all-natural fibers. Thus, it was found that during the first stage, abaca fibers release mainly carbon dioxide, hemp fibers evolve gases containing hydroxyl and carbonyl functionalities, whereas henequen and coconut ones produce carbon dioxide and gases that contain compounds possessing carbonyl and hydroxyl functional groups. During the second stage, all samples released carbon dioxide as well as compounds containing carbonyl, hydroxyl, and aliphatic functional groups.

This paper presents the development and implementation of a 4-port MIMO antenna based on a combination of a Hilbert curve fractal and a reactive load implemented via an open-circuited stub. The integration of these techniques results in a highly compact array with a wide operating bandwidth, extending from 2.3 GHz to 5.8 GHz. This covers the 2.4 GHz ISM band and the 5G New Radio (NR) bands N41, N77, N78, and N79. The total array dimensions are 25 mm & times; 36 mm, equivalent to 0.18 lambda 0 & times; 0.26 lambda 0 at the lower cutoff frequency. The minimum separation between elements is 3 mm, approximately 0.02 lambda 0, which is a very small distance between radiators. However, by incorporating an electromagnetic barrier and giving galvanic continuity, also implemented with a Hilbert curve on the ground plane, an isolation ranging from 15 dB to over 20 dB is achieved across the entire bandwidth, with a peak gain of 1.8 dB. Furthermore, the use of the open-circuited stub stabilizes the antenna's impedance behavior, causing the reactive component to approach 0 Omega, while the real part stabilizes within a threshold close to 50 Ohms, significantly increasing the bandwidth. The final result is a compact 4-port MIMO antenna featuring high isolation, an Envelope Correlation Coefficient (ECC) below 0.05 across the entire range, a Diversity Gain (DG) close to 10, and a stable Total Active Reflection Coefficient (TARC) below -10 dB throughout the operating bandwidth.

Spectroscopic features of the borate glasses having chemical composition: (50 - x - y) B2O3-10 BaO-10 ZnO-10 Li2O-10 Na2O-10 NaF-x Tm2O3-y Er2O3 (x = y = 0; x = 0.5, y = 0; x = 0, y = 0.5; and x = 0.5, y = 0.5, 0.75, 1.0, 1.5, 2.0 mol%) were investigated. Upon 0.808 mu m excitation wavelength, Tm3+/Er3+-codoped samples showed an asymmetric near-infrared (NIR) fluorescence with an effective bandwidth of similar to 63-72 nm within the 1.3-1.65 mu m range. The presence of Tm3+ ions suppressed the Er3+ ion's upconversion (UC) green emissions due to the Er3+ to Tm3+ ion energy transfer (ET) under 0.808 mu m excitation. Er3+ to Tm3+ non-radiative ET has been signified by the NIR and UC fluorescence spectra, Er3+ NIR luminescence decay times, ET efficiency and probability, and energy-level scheme where Er3+ ions function as donors by efficiently absorbing the pump photons and Tm3+ ions as acceptors.