Polytechnic University of Puerto Rico

Scarring is affected by hyperglycemia, infection, persistent inflammation, oxidative stress, and poor vascularization. The purpose of this review is to critically analyze the potential of chitosan-based hydrogels as a biomaterial strategy for healing of diabetic foot ulcers. For the literature selection, scientific articles were selected from Google Scholar and PubMed published between 2020-2026, including both preclinical and clinical studies. For the clinical literature reviewed, CHITOWOUND study offered promising results where the median relative decrease in wound by patients of ChitoCare hydrogel was 92.0% while the placebo patients obtained a 37.0%. Despite this decrease, the difference in wound closure was 16.7% with CHITOWOUND and 4.2% with placebo. Overall, chitosan-based hydrogels present potential as a biomaterial strategy for healing of foot ulcers. However, this topic requires clinical trials with standardized formulations, reproducibility, long-term studies, and a larger number of patients to analyze closure and possible recurrences for diabetic foot wounds.

As global reliance on satellite systems continues to grow, these assets are becoming increasingly vulnerable to sophisticated cyber threats. Despite the rising risk, current satellite cybersecurity strategies often remain reactive and lack the foresight required for proactive measures. This study introduces AERIS: Attack Evolution & Resilience via Integrated Statistics; a predictive modeling framework designed to forecast and characterize satellite cyber threats using historical data from 1985 to 2024. AERIS brings together four statistical tools: Markov Chain modeling, Poisson regression, Bayesian networks, and Survival analysis, to capture attack patterns, frequency dynamics, conditional vulnerabilities, and long-term risk exposure. Findings from AERIS reveal clear geopolitical trends, including a projected 12.1% increase in attack frequency from highrisk adversaries. The framework also highlights the elevated risks faced by LEO and TT&C systems, and demonstrates how attacker identity, orbital characteristics, and system weaknesses collectively influence the severity of impact. Survival modeling within AERIS shows that post-incident resilience declines significantly, dropping from 68% to 26% over 10 years, especially following high-impact attacks. By integrating these models into a unified platform, AERIS transforms scattered historical attack data into forward-looking threat intelligence. The result is a flexible, evidence-based tool to support engineers, policymakers, and cybersecurity professionals in anticipating risks, prioritizing defenses, and designing resilient satellite architectures for the contested space domain.

Thermoplastic polymers are widely used in medical devices because they provide a favorable balance of mechanical performance, manufacturability, biocompatibility, and cost efficiency. Among these materials, polylactic acid (PLA) has become one of the most relevant biodegradable polymers for biomedical applications due to its biocompatibility, processability, and ability to degrade through hydrolytic cleavage of ester bonds [7]. However, PLA-based devices intended for clinical use must undergo sterilization, and gamma irradiation is commonly used for its high penetration and effectiveness in complex geometries. This work presents a qualitative literature review on the effects of gamma sterilization on the physicochemical, mechanical, and degradation behavior of PLA in biomedical applications, supported by a literature-based theoretical finite element analysis (FEA) model using an ASTM D638-style tensile specimen. The reviewed literature indicates that gamma irradiation, commonly applied at sterilization doses around 25 kGy and evaluated in higher-dose or repeated-exposure conditions, can induce significant physicochemical changes in PLA. These changes are mainly associated with free radical formation and chain scission, resulting in reduced molecular weight, changes in crystallinity, reduced elongation at break, decreased tensile performance, and increased brittleness [1], [10], [11], [15]. Theoretical FEA comparisons of non-sterilized, gamma-sterilized, and double-sterilized PLA further illustrated that sterilized conditions may exhibit reduced structural margin under identical tensile loading conditions due to lower yield strength, lower tensile strength, and reduced strain tolerance. Overall, the findings show that gamma sterilization should be treated not only as a final sterility assurance process but also as a material-modifying factor that can affect the mechanical reliability and the predictability of degradation in PLA-based biomedical devices. Therefore, sterilization parameters should be integrated into early-stage biomaterial selection, design verification, and validation planning to ensure the safety, functionality, and long-term performance of PLA-based medical devices.

Ceramic materials are inorganic, predominantly nonmetallic solids whose performance is governed by the interplay among atomic bonding, crystal structure, processing, microstructure, and functional properties. Their ionic and covalent bonding provides high hardness, thermal and chemical stability, wear resistance, and diverse electrical behavior, but also limits plastic deformation and increases sensitivity to flaws, porosity, grain boundaries, and residual stresses. This review examines ceramics through the processing–microstructure–property–performance relationship, emphasizing the effects of crystal chemistry, defects, grain size, porosity, and phase stability on mechanical, thermal, electrical, and biological behavior. Conventional sintering, sol–gel processing, and additive manufacturing are discussed as key routes for controlling densification, porosity, geometry, and composition. Biomedical ceramics, including alumina, zirconia, calcium phosphates, hydroxyapatite, tricalcium phosphate, and bioactive glasses, are also reviewed. Emerging topics include nanoceramics, smart ceramics, composites, multimaterial manufacturing, defect engineering, immunomodulatory bioceramics, and sustainable processing. Major challenges remain in brittle fracture, processing heterogeneity, degradation control, scale-up, and the porosity–strength trade-off. Future advances will require integrating advanced manufacturing, multiscale characterization, predictive modeling, and data-driven design.

First-semester performance is a practical indicator of students’ transition into tertiary education and a point at which institutions can intervene early. This study examined an analytic dataset of 2,048 incoming students admitted to 10 academic programs in the College of Business Administration at the University of Puerto Rico, Río Piedras Campus from 2018–2019 to 2022–2023. An exploratory course-level analysis identified courses with high percentages of critical outcomes, particularly in quantitative and general education areas. Nested and cohort-specific regression models examined academic, sociofamilial, demographic, and institutional constructs associated with first-semester grade point average (GPA). Academic background produced the largest improvement in final nested model fit, which explained 28.5% of the adjusted variance in first-semester GPA. High school GPA and verbal aptitude were the most consistent predictors across cohorts. The findings support ethically designed early alert systems that use student-level indicators alongside course-level interventions to strengthen achievement, retention, and equitable student success.