Search Results (41)

In the present manuscript, the influence of reaction time on the hexagonal-to-monoclinic phase transition in hydroxyapatite (HAp) nanofibers synthesized via a low-temperature modified hydrothermal method at 100 °C is investigated. The resulting nanofibers were highly crystalline and stoichiometric, with a Ca/P ratio of approximately 1.67. Comprehensive structural and functional characterization, combining X-ray diffraction with Rietveld refinement, Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM), and resonance-tracking piezoresponse force microscopy (RT-PFM), was employed to elucidate the role of the non-centrosymmetric monoclinic P2₁/b phase in governing HAp’s structural and piezoelectric properties. The analyses indicated a time-dependent phase evolution from hexagonal (P6₃/m) to monoclinic (P2₁/b), with exclusive formation of the hexagonal phase at 6 h and a clearly dominant monoclinic fraction (73.56%) after 24 h. Nanofibers synthesized for 48 h comprised approximately 98% monoclinic HAp and exhibited elongated morphologies with an average length of 354.82 nm and diameter of 45 nm. RT-PFM measurements confirmed a pronounced piezoelectric response associated with the monoclinic phase, yielding an effective piezoelectric coefficient (d_eff) of 19.85 pm/V. In vitro MTT assays demonstrated that the high monoclinic content did not compromise biocompatibility, as cell viability and cytotoxicity met the requirements of ISO 10993 and ASTM F895 standards. These findings offer new insights into how monoclinic ordering governs the piezoelectric behavior of HAp and suggest a promising strategy for enhancing its performance in biomedical applications. Full article

Noise pollution poses a serious threat to human health and well-being, especially in educational environments where concentration and learning are essential. While urban noise has been widely studied, its effects within university settings remain underexplored. This study investigates environmental noise and student perceptions on two campuses of the University of Guadalajara, Mexico—one located in an urban area and the other in a semi-rural setting. Noise levels were measured using the CESVA-SC260 integrating instrument (CESVA Instruments, SLU, Barcelona, Spain), and student perceptions were gathered through a survey. A total of 731 students participated, with 357 from the urban campus and 374 from the semi-rural one. Results showed that noise levels on both campuses frequently exceeded the WHO’s recommended limit of 55 dB(A) for educational facilities, with readings between 40.9 and 85.0 dB(A); 89% of measurements surpassed the threshold. Major sources of noise included vehicular traffic, student gatherings, and construction-related machinery. Survey responses indicated that 41% of students perceived noise as a health risk, and 96% reported adverse effects on well-being and identified it as a disruptor of academic tasks. These findings underscore the pressing need for targeted noise management strategies in university environments and call for further research into effective, context-specific interventions that enhances learning conditions. Full article

Camptothecin (CPT) is a natural alkaloid with potent antiproliferative activity, mediated by the inhibition of Topoisomerase I (Topo I), an essential enzyme for deoxyribonucleic acid (DNA) replication. However, its clinical application has been limited by low solubility and the instability of the lactone ring under physiological conditions, both of which decrease its efficacy. Semi-synthetic analogs such as irinotecan (CPT-11) and topotecan (TPT) have been developed and approved for the treatment of various types of cancer; however, challenges related to drug resistance and side effects continue to arise. Therefore, nanomedicine and nanoparticle-based delivery systems, including nanoemulsions, liposomes, and antibody–drug conjugates (ADCs), emerge as promising strategies to improve the stability, bioavailability, and effectiveness of CPT, despite significant challenges such as scalability, pharmacokinetic variability, and regulatory requirements. This review discusses recent advances in CPT, its analogs, and these delivery platforms, highlighting its potential to optimize cancer therapy and reduce toxicity while outlining translational challenges such as scalability, pharmacokinetic variability, and regulatory requirements. Full article

Increasing the nutritional composition of food is a strategy to add added value to products in key agrochains, contributing to food security, and providing nutritional compounds available to improve selected nutritional deficiencies. An increased level of β-carotenes is an important contribution to reducing vitamin A deficiency. In Colombia, the Bioversity-CIAT alliance and Agrosavia evaluated eight cassava genotypes with the aim of identifying promising candidates for commercial release adapted to Caribbean region in Colombia. Experimental genotypes were established together with two checks, in six locations representing dry and humid Caribbean region. Agronomic evaluations, combined with culinary quality assessments and participatory evaluations of consumer preferences, enabled a comprehensive analysis of each genotype. The experimental genotypes exhibited different plant architecture, with some showing greater height and higher first branching than current varieties. However, excessive plant height in certain genotypes led to increased susceptibility to lodging, negatively affecting the quality of planting material. While only a few genotypes matched the check varieties in root yield (20 T/ha), several demonstrated significantly improved nutritional quality due to higher accumulation of total and β-carotenes (>8 µg/gr and >5 µg/gr, respectively) compared to current varieties (<2 µg/gr and 1.5 µg/gr, respectively). Cooking quality and consumer acceptance were key determinants in the final selection. Among the evaluated lines, genotype GM3426-5 stood out for its favorable agronomic performance, high provitamin A content, and excellent root and cooking quality. Nevertheless, further steps are required before its commercial release, as the product profile for cassava destined for human consumption must prioritize food quality and consumer preferences. Full article

Seismic data processing is essential in hydrocarbon exploration, with normal moveout (NMO) correction being a pivotal step in enhancing seismic signal quality. However, conventional NMO correction often suffers from the stretch effect, which distorts seismic reflections and degrades data quality, especially in long-offset data. This study addresses the issue by analyzing synthetic models and proposing a nonhyperbolic stretch-free NMO correction technique. The proposed method significantly improves seismic data quality by preserving up to 90% of the original amplitude, maintaining frequency content stability at 30 Hz, and achieving a high reduction of stretch-related distortions. Compared to conventional NMO, our technique results in clearer seismic gathers, enhanced temporal resolution, and more accurate velocity models. These improvements have substantial implications for high-resolution subsurface imaging and precise reservoir characterization.This work offers a robust and computationally efficient solution to a longstanding limitation in seismic processing, advancing the reliability of exploration in geologically complex environments. Full article

The northern Yucatán Peninsula hosts a complex karstic environment shaped by carbonate platform development and the Chicxulub impact event, making subsurface characterization crucial for geological and hydrogeological studies. This work aimed to resolve the shallow crustal structure and identify major tectonic features that influence karst processes and groundwater dynamics. We applied a rapid 3D gravity inversion method, linear back projection (LBP), to Bouguer anomaly data, combined with Euler deconvolution to map shallow and deep fault systems. The inversion produced a high-resolution density model down to 12.8 km depth, revealing key geological structures. Multilevel thresholding delineated significant low-density basins, notably the Chicxulub crater, as well as buried sedimentary basins. Euler solutions identified fault networks that coincide with areas of intense karstification, particularly in the eastern peninsula. Results highlight the interplay between impact-related tectonics and karst evolution, influencing groundwater flow paths and recharge zones. This study demonstrates the effectiveness of gravity inversion and Euler deconvolution for regional crustal imaging in carbonate platforms and emphasizes the need for further local-scale surveys to investigate coastal aquifer vulnerability and saltwater intrusion processes. Full article

This study investigates the stiffening phenomena caused by aging and low-dosage Kraft lignin addition on a soft bitumen (PG58S–28)- used in cold climate regions. Through a combination of physico-chemical and rheological analyses, including Fourier-transform infrared spectroscopy (FTIR), Brookfield rheometer viscosity (BRV), dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and complex shear modulus (G*) tests, the impacts of lignin modification and thermo-oxidative aging are evaluated. In particular, the anti-aging potential of lignin is scrutinized. The results indicate that while the carbonyl index effectively tracks bitumen aging, the sulphoxide index is less reliable due to high initial S=O bond content in Kraft lignin and greater repeatability variability. Standard rheological tests (BRV, DSR, MSCR, and BBR) show that long-term aging significantly increases bitumen stiffness, while lignin modification leads to a moderate stiffening effect but does not exhibit any noticeable anti-aging properties. The G* analysis confirms that aging strongly influences bitumen rigidity, particularly at low and intermediate equivalent frequencies, while lignin acts similarly to an inert filler, with minimal effects on linear viscoelastic (LVE) behaviour. Overall, the study concludes that the addition of Kraft lignin at low dosage does not alter the fundamental aging mechanisms of bitumen, nor does it provide significant antioxidant benefits. These findings contribute to the ongoing discussion on bio-based bitumen modifiers and their role in sustainable pavement materials. Full article

Human respiratory syncytial virus (HRSV) is a leading cause of severe respiratory infections among children, older adults, and immunocompromised individuals. The COVID-19 pandemic and the non-pharmacological interventions to mitigate it resulted in significant changes in HRSV epidemiology and seasonality patterns. Worldwide, there was a considerable reduction in the number of HRSV infections during that period, and the impact of those changes on genotype distribution is still not fully understood. In this work, we analyzed the genotypic characteristics of HRSV strains detected between 2021 and 2024 in Mexico with the aim of identifying changes in circulating lineages. HRSV positive samples collected in five states in Mexico were used. The complete viral attachment glycoprotein gene was sequenced, and phylogenetic inference was performed using datasets including all sequences available at GenBank and GISAID until 30 June 2024. We obtained 114 HRSV sequences (63.2% HRSV-A and 36.8% HRSV-B); 19 were from the 2021–2022 season, 53 from 2022–2023, and 42 from 2023–2024. All HRSV-A sequences clustered with sequences from other countries within A.D lineages, including A.D.1, A.D.3, A.D.5.1, and A.D.5.2 lineages. All HRSV-B sequences clustered in the B.D.E.1 lineage with sequences collected between 2020 and 2024. In conclusion, the characterization of HRSV viruses circulating in Mexico during and after the SARS-CoV-2 pandemic and comparison to all available sequences reported to date corroborates that, on a global scale, HRSV-A viruses of several A.D lineages circulate simultaneously, while HRSV-B viruses are restricted to the B.D.E.1 lineage. Full article

Background and Objective: Primary Progressive Aphasias (PPAs) are rare neurodegenerative disorders classified within frontotemporal lobar degeneration (FTLD) and typically manifest between 45 and 70 years of age. In Mexico—and many other countries—reliable epidemiological data are lacking; however, estimates suggest that PPA accounts for 0.5–2.5% of neurodegenerative disease cases in Memory Clinics, with an incidence of approximately 1 per 100,000 and an average survival of 8 years. This review aims to provide clinicians with an overview of PPA’s epidemiology, clinical features, and classification, thereby enhancing understanding of its subtypes and distinguishing characteristics from other aphasic conditions, such as vascular aphasia. Methods: This narrative review was conducted through a literature search using databases such as PubMed and Scopus. Relevant studies addressing the epidemiology, clinical presentation, and classification of PPA were identified, selected, and synthesized to offer a broad, clinically oriented overview of the condition. This approach was chosen to inform clinical practice and highlight the need for further targeted investigations, such as future systematic reviews focusing on specific aspects like therapeutic strategies. Key Contents and Findings: (a) Epidemiology: PPA is estimated to affect 0.5–2.5% of patients with neurodegenerative diseases in Memory Clinics, with an incidence of roughly 1 per 100,000. Average survival time is around 8 years (ranging from 3 to 17 years), with a generally balanced gender ratio, though some studies indicate a predominance of men. A positive family history is observed in 20–40% of cases, with about 10% following an autosomal dominant inheritance pattern. (b) Clinical Characteristics and Classification: PPA is marked by a gradual decline in language abilities, differentiating it from vascular aphasias. Subtypes include non-fluent forms (non-fluent progressive aphasia [nfPPA] and logopenic progressive aphasia [lPPA]), fluent forms (progressive fluent aphasia [PFA] and semantic dementia [SD]), and mixed forms (progressive mixed aphasia [PMA]). The neurodegenerative process in PPA extends beyond vascular boundaries, often resulting in presentations that deviate from classical Broca’s and Wernicke’s aphasias. Common symptoms include difficulties in word finding and naming, sometimes mistaken for memory loss, and, in the case of semantic dementia, personality changes that may go unnoticed by the patient. Conclusions: PPA is a heterogeneous and complex group of neurodegenerative disorders with significant clinical variability and a profound impact on patients and their families. While current epidemiological data are limited, this review emphasizes the need for further research to better delineate disease progression and refine diagnostic and therapeutic approaches. Future systematic reviews will be essential to address specific aspects of PPA, such as treatment strategies, to further improve patient care. Full article

Background: The few epidemiologic studies of infection exposure in early life and acute leukemia (AL) risk in Latino children have yielded inconsistent results, suggesting a possible effect of ethnicity. Here, we examined the correlation between infection exposure and acute leukemia risk in children from Mexico City—One of the biggest Latino cities worldwide. Methods: This study included 1455 Mexican children diagnosed with de novo AL (2002–2016), and 1455 control individuals frequency-matched by age and health institution. The AL population included acute lymphoblastic leukemia (ALL), Pre-B ALL, and acute myeloblastic leukemia (AML). Logistic regression analyses were performed to investigate direct and indirect proxies of infection in children or their mothers. Results: Upper respiratory tract infections during the child’s first year of life were a risk factor for AL (OR, 2.76; 95% CI, 1.48–5.15), including ALL (OR, 3.14; 95% CI, 1.67–5.89) and Pre-B (OR, 3.11; 95% CI, 1.63–5.96). Mother’s infections before and during pregnancy were protective factors against AL (OR, 0.55; 95% CI, 0.47–0.64; and OR, 0.61; 95% CI, 0.52–0.72, respectively). These associations included ALL and Pre-B. In contrast, only mothers’ infections before pregnancy and respiratory tract infections were protective factors against AML (OR, 0.45; 95% CI, 0.33–0.62; and OR, 0.50; 95% CI, 0.37–0.68, respectively). Conclusions: Infections during the first year of life were associated with AL development in children of Mexico City. Additionally, mothers’ exposure to respiratory tract infections before and during pregnancy reduced the AL risk in this Latino population. Full article

Mapping potential fire intensity is a fundamental tool for fire management planning. Despite the wide use of Fire Radiative Power (FRP) as an indicator of expected fire intensity and fire emissions, very few studies have spatially analyzed the role of remotely sensed proxies of vegetation productivity to explain FRP. The current study aimed at modeling and mapping the relationships between aboveground biomass and Moderate Resolution Imaging Spectroradiometer (MODIS) maximum FRP, at 1 km pixel, in 2011–2020, for each of 46 fuel regions in the entirety of Mexico. Maximum FRP–biomass relationships supported a novel hypothesis of varying constraints of fire intensity. In lower-productivity areas, such as semiarid shrub- and grass-dominated ecosystems, fine fuel loads limited fire occurrence and FRP was positively related to biomass. In the more productive areas, such as temperate or tropical forests, a humped relationship of FRP against biomass was observed, suggesting an intermediate-productivity hypothesis of maximum fire intensity within those regions. In those areas, the highest fire intensity was observed in the intermediate biomass areas, where surface (timber understory) and crown fuel availability, together with higher wind penetration, can result in crown fires. On the contrary, within the most productive areas, the lowest intensity occurred, likely due to weather and fuel (timber litter) limitations. Full article

In this paper, we present the synthesis of composite materials comprised of α-cellulose and sugarcane bagasse cellulose fibers grafted with lactic acid and ε-caprolactone. These fibers were incorporated as reinforcements into a PLA matrix by extrusion, producing composite materials with improved mechanical properties. The grafting of lactic acid and ε-caprolactone onto the fibers was confirmed by FTIR spectroscopy, demonstrating the chemical modification of the fibers. The morphology of the fibers and composites was analyzed through scanning electron microscopy (SEM), showing that the fibers are encapsulated within the polymeric matrix. This suggests good PLA–fiber interaction for the 90 PLA/10 α-Cel, 90 PLA/10 LAC-g-α-Cel, and 90 PLA/10 ε-CL-g-α-Cel composite materials. The obtained composite materials were tested under tensile loading. Incorporating 10 wt% of LAC-g-FBA-Cel and α-Cel-g-FBA-Cel grafted fibers into the PLA matrix improved the tensile modulus by 28% and 12%, respectively, compared with PLA. The maximum tensile strength values obtained were for composite materials with 10 wt% PLA/α-Cel, LAC-g-α-Cel, and FBA-Cel with 23, 27, and 37% concerning PLA. DSC thermal studies showed a reduction in the glass transition temperature in the composites with grafted fibers. The results suggest better interfacial adhesion between the PLA matrix and both grafted and non-grafted α-cellulose fibers, which contributes to the observed improvements in the mechanical and thermal properties of the composite materials. The results demonstrate that the composites can be produced through extrusion. Once the optimal concentration has been determined, α-cellulose or sugarcane bagasse grafted with lactic acid and ε-caprolactone can be incorporated into the PLA matrix, exhibiting adjustable properties. Full article

Within the geophysical exploration utilising seismic methods, it is well known that if the explored distances are much greater than the wavelength of the seismic waves with which the exploration is carried out, the ray approach of the wave theory can be used. In this way, when the rays travel through an inhomogeneous medium, they follow curved trajectories, which is imperative to determine the geological features that produce reflection and refraction phenomena. In this paper, a simple algorithm for the calculation of the trajectory of a seismic beam through an inhomogeneous stratum is presented. For this, the construction of a pseudo-Riemannian metric is required from the function of P-wave velocities of the geological stratum. Thus, the problem is inverted because instead of finding the curved trajectory of the seismic beam in a background with a Euclidean metric, it is proposed that the beam follows a geodesic of a curved space-time specific to each stratum, becoming a simple and automatic process using the differential geometry apparatus. For the reader to gain insight into this tool, different geological setups from idealised ones up to a salt dome are presented. Full article

Background: Risk factors for severe dengue manifestations have been attributed to various factors, including specific serotypes, sex, and age. Mexico has seen the re-emergence of DENV-3, which has not circulated in a decade. Objective: To describe dengue serotypes by age, sex, and their association with disease severity in dengue-positive serum samples from epidemiological surveillance system units. Materials and Methods: A descriptive analysis was conducted to evaluate the frequency of dengue severity by sex, age, disease quarter, geographical location, and dengue virus serotypes. The study was conducted using laboratory samples from confirmed dengue cases through RT-qPCR from the epidemiological surveillance laboratory network of the Mexican Social Security Institute, Mexico. Simple frequencies and proportions were calculated using the z-test for proportional differences between groups. Bivariate analysis with adjusted Chi2 was performed, and binary logistic regression models were constructed using the forward Wald method considering the model’s predictive capacity. The measure of association was the odds ratio, with 95% confidence intervals. Statistical significance was set to an alpha level of <0.05. Results: In 2023, 10,441 samples were processed for dengue RT-qPCR at the IMSS, with a predominance of serotype DENV-3 (64.4%). The samples were mostly from women (52.0%) and outpatient cases (63.3%). The distribution of dengue severity showed significant variations by age, with a lower proportion of severe cases in young children and a higher proportion in the 5- to 14-year-old group. Hospitalizations increased significantly with severity. Warm regions had more cases overall and severity. Cases were most frequent from July to September. While DENV-2 was associated with severity, DENV-4 was not. Binary regression identified higher risk in women, age extremes, and DENV-2, with an overall predictive model of 58.5%. Conclusions: Women, age groups at the extremes of life, and the DENV-2 serotype presented severe risk of dengue in a population with social security in Mexico during 2023. Full article