Howard Ramírez-Malule

2-Aminopyrimidine (2-AP)–based compounds have gained considerable attention for their anticancer potential, demonstrated by their ability to inhibit tumor growth across diverse malignancies in preclinical models, and several candidates have also progressed into the clinical management of patients with cancer. In this study, a bibliometric analysis was conducted using Scopus to evaluate the research landscape of 2-AP. Two complementary datasets were analyzed: a general dataset including 793 publications from 1990 to 2025, and a cancer-focused dataset including 81 publications from 2004 to 2025. Data were analyzed using VOSviewer to identify trends in publication output, research areas, and collaboration networks. The results revealed a significant increase in research output since 2004, with most studies concentrated in the fields of Chemistry (40.2%), Pharmacology, Toxicology and Pharmaceutics (14.5%), and Biochemistry, Genetics and Molecular Biology (14.2%). Enzymatic assays, X-ray crystallographic studies, and molecular docking approaches assessing the anticancer activities of 2-AP analogs have emerged as a key research focus. Geographically, China, India and the United States were identified as the most productive contributors. These findings highlight the increasing importance of the 2-AP scaffold as a structural motif for incorporation into novel molecules in the context of oncology drug development.

Liquid organic hydrogen carriers (LOHC) have emerged as a promising technology for the safe, efficient, and reversible storage and transportation of hydrogen, offering a viable pathway toward the development of a hydrogen-based economy. Despite the rapid expansion of this research field, a comprehensive understanding of its scientific evolution, intellectual structure, and emerging research directions remains limited. This study presents a comprehensive bibliometric and thematic analysis of LOHC research based on 1140 publications indexed in the Scopus database between 2007 and 2025. Bibliometric indicators, scientific mapping, Bradford’s and Lotka’s laws, thematic evolution, and strategic thematic mapping were performed using VOSviewer and Bibliometrix/Biblioshiny. The results reveal an exponential increase in scientific production after 2016, reflecting the growing global interest in LOHC technologies. Bradford’s law identified a highly concentrated publication landscape dominated by a small core of specialized journals, whereas Lotka’s law demonstrated that scientific production is driven by a limited group of highly productive authors. Keyword network and thematic evolution analyses show a clear transition from fundamental hydrogen storage concepts toward advanced catalyst development, molecular design, quantum chemical calculations, machine learning, techno-economic assessment, and hydrogen transport applications. Strategic thematic mapping further indicates that computational methodologies and sustainability-oriented analyses are becoming emerging drivers of future research. Overall, this study provides a comprehensive overview of the conceptual, intellectual, and thematic evolution of LOHC research while identifying the principal scientific trends and technological opportunities expected to shape the next generation of hydrogen storage systems.

Plastic pollution has emerged as one of the most pressing environmental, health, and socio-economic challenges worldwide, driving rapid growth in scientific research over the last decade. This study presents a comprehensive bibliometric analysis of global research on plastic particles as environmental contaminants published between 2015 and 2025. The search expression employed was (*plastic) AND (pollut* OR contaminat*) to retrieve publications addressing plastic pollution and the occurrence of plastics as environmental contaminants. A total of 50,946 documents, including articles, reviews, and book chapters indexed in the Scopus database, were analyzed using VOSviewer 1.6.20 and Bibliometrix/Biblioshiny v. 2026.01.1 Build 403 to evaluate publication trends, collaboration networks, conceptual structure, and the bibliometric organization of the field. The analysis revealed a sustained increase in scientific production, led by China (15,667 publications), the United States (5540), and India (5374), with Environmental Science representing the dominant subject area (31.2%). To characterize the most recent thematic structure, keyword co-occurrence analysis was specifically performed using articles published during 2024–2025. Keyword co-occurrence and thematic mapping identified microplastics, nanoplastics, and adsorption as the principal motor themes, while circular economy, sustainability, biodegradation, and machine learning emerged as rapidly expanding research directions. Author-productivity and journal-dispersion analyses revealed a concentrated scientific structure, characterized by a relatively small group of highly productive authors and a core set of journals accounting for a substantial proportion of the literature but with significant deviations from the theoretical Lotka and Bradford distributions. Furthermore, the collaboration analysis revealed an irregular geographic distribution of publication output and international co-authorship, with the largest absolute contributions concentrated in China, the United States, India, and several European countries. By integrating bibliometric indicators with policy frameworks, funding patterns, and sustainability perspectives, this study provides a system-level understanding of the evolution of research on plastic pollution. It identifies strategic priorities to support evidence-based environmental governance, circular economy implementation, and future research agendas.

A controlled composting biodegradation system was implemented to evaluate a wood–plastic composite (WPC) composed of wood fibers and recycled HDPE (rHDPE), in accordance with ASTM D5338, by measuring CO₂ capture over 45 days. This evaluation was complemented with mechanical and physicochemical characterization, including stereomicroscopy/SEM, mass loss, water absorption, contact angle, tensile strength, FTIR, TGA, and DSC. The results showed 6.12% biodegradation, classifying the material as neither biodegradable nor compostable. SEM analysis revealed increased surface roughness, cracks, and microbial-like structures, together with a 10% decrease in contact angle. The mechanical properties declined by 33% (tensile strength), despite only 1.26% mass loss, which was attributed to weakening of the matrix–fiber interfacial adhesion due to water absorption. TGA, DSC, and FTIR supported the interpretation that degradation occurred preferentially in the wood fibers.

BACKGROUND: The growing demand for biodegradable polymers has positioned polyhydroxybutyrate (PHB) as a sustainable alternative to petrochemical plastics. Microbial synthesis from renewable, low‐cost substrates such as cassava starch‐derived dextrose offers a promising route, but feeding strategies and metabolic understanding remain critical. This study aimed to evaluate the effect of fed‐batch pulse feeding on PHB production by Cupriavidus necator DSM 428 and to integrate experimental results with flux balance analysis (FBA). RESULTS: Three pulse‐feeding strategies were assessed. Two pulses containing carbon and nitrogen at 24 and 48 h (C/N ratio 73) led to 33.55% (w/w) PHB accumulation. A single dextrose‐only pulse at 48 h led to 25.12% (w/w), while delaying this pulse to 60 h increased PHB accumulation to 50.40% (w/w). Feeding at the onset of stationary phase enhanced biomass growth but reduced PHB storage, whereas late feeding favored polymer accumulation, likely due to nitrogen limitation. PHB was characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, thermogravimetric analysis, and differential scanning calorimetry, confirming its expected structural and thermal properties. FBA with i CNH2025A showed strong correlation with experimental data, accurately predicting growth and carbon flux redirection toward PHB synthesis. CONCLUSION: The integration of fed‐batch pulse feeding with FBA provides new insights into the metabolic and process factors driving PHB accumulation from cassava‐based substrates. The results highlight the importance of feeding timing for optimizing yields and demonstrate the value of metabolic modeling in guiding sustainable bioprocess design. © 2026 Society of Chemical Industry (SCI).

The aviation industry faces increasing pressure to reduce its environmental impact and achieve net-zero emissions by 2050. In this context, sustainable aviation fuels (SAF) have emerged as a critical alternative to conventional jet fuels. This study provides a comprehensive analysis of SAF technologies from a chemical engineering perspective, highlighting key production routes, technological maturity levels, and implementation challenges. A bibliometric analysis using the Scopus database and VOSviewer software was conducted to identify research trends and thematic clusters in SAF literature. The analysis reveals a growing interest in advanced biofuels and physicochemical conversion technologies, particularly those supported by catalytic and thermochemical processes. Certified and emerging SAF pathways were examined with respect to their process efficiency, feedstock availability, and scalability. Additionally, the study explores the potential of Latin America as a strategic region for SAF development, considering its abundant biomass resources and ongoing pilot projects. This critical and holistic analysis aims to support researchers, engineers, and policymakers in understanding the current state and future directions of SAF technologies within the framework of chemical process design and optimization. Overall, Hydroprocessed Esters and Fatty Acids Synthetic Paraffinic Kerosene (HEFA-SPK) and Fischer–Tropsch Synthetic Paraffinic Kerosene (FT-SPK) are identified as the most mature and widely deployed SAF production routes, whereas Alcohol to Jet (ATJ), Synthesized Iso-Paraffins (SIP), and Direct Sugar to Hydrocarbons (DSHC) remain at earlier technological stages despite their long-term potential for feedstock diversification and reduced environmental impacts. The analysis also underscores Latin America, where abundant biomass resources, consolidated agro-industrial systems, and emerging SAF research initiatives create favorable conditions for future development and deployment.

The mechanical, thermal, physicochemical and structural properties of a thermoplastic cassava starch obtained by a twin-screw extrusion process were evaluated, using glycerol and isosorbide as plasticizers at different concentrations (30, 35 and 40% by weight) and storage times (1, 15 and 30 days) under controlled conditions of relative humidity of 47 ± 2% and temperature of 25 ± 2 °C. The results obtained show a decrease in tensile strength and modulus of elasticity and an increase in elongation in the initial measurements, suggesting that, in both cases, a plasticization phenomenon via absorption of humidity predominated in short times, while at prolonged times, a rigidification of the material occurred due to the generation of a retrogradation process. Likewise, a higher tensile strength and lower elongation were found in the materials plasticized with isosorbide. Finally, it was observed that the retrogradation phenomenon was more evident in the thermoplastic starch samples made with glycerol, and that the starches plasticized with isosorbide had lower moisture absorption, higher crystallinity and a predominantly Eh-type crystalline pattern, related to greater stability over time.

The production of volatile fatty acids (VFAs) through the acidogenic fermentation of wastewater has garnered significant attention in recent years. This study examines the kinetics of VFA production in batch reactors using cassava wastewater as a substrate under previously identified conditions (initial pH of 5.7, S/M ratio of 4 gCOD/gVS, and temperature of 34 ± 1 °C). Additionally, this study identifies the best-fit models for estimating kinetic parameters related to the consumption of soluble organic matter and VFA production. VFA production yields ranged from 0.15 to 0.44 gCOD_VFA/gCOD over the 12-day fermentation period, with the highest yield observed on day 9. The acids produced consisted of 29.7% acetic acid, 43.3% propionic acid, and 27.0% butyric acid. The modified Gompertz and first-order with residual models effectively described the consumption of soluble organic matter, while the first-order and BPK models accurately represented the VFA production. These models showed the highest R² values and the lowest RMSE and AIC values. Cassava wastewater is a low-cost substrate with potential for VFA recovery. Its kinetic modeling provides valuable insights for the design, control, and scale-up of acidogenic reactors.

The production of volatile fatty acids (VFAs) through the acidogenic fermentation of wastewater is an emerging technology that requires further research to optimize operational variables for specific substrates. Cassava wastewater, which is a byproduct of the cassava sour starch extraction process, has been minimally studied regarding its potential for VFA production through acidogenic fermentation. Batch reactors were used to evaluate the effects of the substrate-to-microorganism (S/M) ratio and temperature on VFA production from cassava wastewater. The results showed no statistically significant differences between the evaluated S/M ratios. The maximum total VFA concentration observed was 2214.64 mg of acetic acid (HAc)/L (0.32 gCOD_VFA/gCOD), which was achieved at a S/M ratio of 4 gCOD/gVS. This concentration was predominantly composed of acetic acid (42.7%), followed by butyric acid (30.1%) and propionic acid (24.6%), with a minor quantity of isovaleric acid (2.6%). The statistical analysis for the temperature variable showed significant differences between the evaluated conditions. The maximum concentration of total VFAs was 2650.19 mgHAc/L (0.45 gCOD_VFA/gCOD) at 34 ± 1 °C, with acetic (40.9%), butyric (29.8%), and propionic (29.3%) acids as primary metabolites. Cassava wastewater shows promise as a potential substrate for VFA production, warranting evaluation in continuous reactors.