Future trends of additive manufacturing in medical applications: An overview.

Additive Manufacturing (AM) has recently demonstrated significant medical progress. Due to advancements in materials and methodologies, various processes have been developed to cater to the medical sector's requirements, including bioprinting and 4D, 5D, and 6D printing. However, only a few studies have captured these emerging trends and their medical applications. Therefore, this overview presents an analysis of the advancements and achievements obtained in AM for the medical industry, focusing on the principal trends identified in the annual report of AM3DP.

Maximal Respiratory Pressure Reference Equations in Healthy Adults and Cut-off Points for Defining Respiratory Muscle Weakness.

INTRODUCTION: Maximal inspiratory and expiratory pressures (PImax/PEmax) reference equations obtained in healthy people are needed to correctly interpret respiratory muscle strength. Currently, no clear cut-off points defining respiratory muscle weakness are available. We aimed to establish sex-specific reference equations for PImax/PEmax in a large sample of healthy adults and to objectively determine cut-off points for respiratory muscle weakness. METHODS: A multicentre cross-sectional study was conducted across 14 Spanish centres. Healthy non-smoking volunteers aged 18-80 years stratified by sex and age were recruited. PImax/PEmax were assessed using uniform methodology according to international standards. Multiple linear regressions were used to obtain reference equations. Cut-off points for respiratory muscle weakness were established by using T-scores. RESULTS: The final sample consisted of 610 subjects (314 females; 48 [standard deviation, SD: 17] years). Reference equations for PImax/PEmax included body mass index and a squared term of the age as independent variables for both sexes (p<0.01). Cut-off points for respiratory muscle weakness based on T-scores ≥2.5 SD below the peak mean value achieved at a young age were: 62 and 83cmH2O for PImax and 81 and 109cmH2O for PEmax in females and males, respectively. CONCLUSION: These reference values, based on the largest dataset collected in a European population to date using uniform methodology, help identify cut-off points for respiratory muscle weakness in females and males. These data will help to better identify the presence of respiratory muscle weakness and to determine indications for interventions to improve respiratory muscle function.

Expansion of marine pollution along the coast: Negative effects on kelps and contamination transference to benthic herbivores?

Heavy metals and polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants that frequently co-occur in coastal environments. These contaminants can have negative impacts on the health and stability of marine and coastal ecosystems, affecting both the organisms themselves and the humans who consume them. A coastal industrial park in central Chile, housing a coal thermal power plant and other industrial activities, contributes to such pollution of coastal waters; however, neither the spatial alongshore distribution of heavy metals and PAHs, nor an assessment of their ecological effects on the biota have been systematically documented to date. In this paper, we present evidence regarding the direct negative effect of contamination by heavy metals and PAHs on the early life stages of kelps-being extremely harmful to their population persistence near highly polluted sites-as well as the indirect effects of their transference through the food web to higher trophic levels, leading to negative consequences for the feeding intake, growth, fertility, and larval development of marine herbivores that consume the contaminated seaweed. Likewise, the dispersion of contaminants by ocean currents can exacerbate the effects of pollution, having an adverse influence on marine ecosystem health even at sites far from the pollution source. Therefore, it is necessary to investigate the distribution patterns and extent of pollution along the coast to understand the impact of heavy metals and PAHs pollution on seaweed populations and the food web. It is considered critical for the development of effective environmental policies and regulations to protect these ecosystems and the people who depend on them.

Challenges and opportunities for modeling coupled human and natural systems.

With the growing recognition of coupled human and natural systems (CHANS), modeling CHANS with two-way feedbacks has become a frontier research area and a critical tool to achieve sustainability. The challenges in CHANS modeling and opportunities to advance its science and application to promote the sustainability of CHANS are discussed in this paper.

Manejo endoscópico de fístulas del seno piriforme. Reporte de dos casos / Endoscopic management of piriform sinus fistula. Two cases report

Resumen Caso 1: Femenino de cuatro años de edad con absceso cervical izquierdo recurrente por fístula del seno piriforme izquierdo tratada finalmente con electrocoagulación endoscópica sin recidivas en más de siete meses. Caso 2: Masculino de seis años de edad con absceso cervical izquierdo recurrente por fístula del seno piriforme izquierdo tratado con electrocoagulación endoscópica sin recidivas en más de 6 meses. Discusión: Las fistulas del seno piriforme son poco comunes, resueltas en forma quirúrgica con amplias disecciones cervicales y en ocasiones con hemitiroidectomías. No suelen sospecharse sino hasta la recurrencia del cuadro. Aunque no todos los abscesos cervicales son por fístulas del seno piriforme, recomendamos descartarla en casos de recidiva sobre todo en el lado izquierdo del cuello; acompañando el drenaje con exploración endoscópica. De confirmarse el diagnóstico se ofrece tratamiento por electrocoagulación en la misma intervención con mejores resultados al evitar los riesgos que implica la resección extensa del tratamiento convencional. En nuestros casos usamos endoscopía flexible y electrocoagulación con resultados superiores en relación con el tratamiento quirúrgico convencional. Limitaciones: Solo se trata de dos casos, pero corresponden a una entidad poco frecuente. Valor: Se muestra como alternativa el tratamiento endoscópico con electrocoagulación con mejores resultados en relación con el manejo tradicional para los casos de fístula del seno piriforme en niños.

Abstract Case 1: A 4-year-old female with a recurrent left cervical abscess due to a left piriform sinus fistula finally treated with endoscopic electrocoagulation without recurrences for more than 7 months. Case 2: 6-year-old male with recurrent left cervical abscess due to left piriform sinus fistula treated with endoscopic electrocoagulation without recurrences for more than 6 months. Discussion: Piriform sinus fistulas are rare and are surgically corrected with extensive cervical dissections and occasionally hemithyroidectomies. They are not usually noticed as such until the recurrence. Although not all cervical abscesses are due to piriform sinus fistulas, we recommend ruling out in cases of recurrence, especially on the left side of the neck, accompanying by drainage with endoscopic exploration. If the suspicion is confirmed, electrocoagulation treatment is offered in the same intervention with better results by avoiding the risks involved in an extensive resection with conventional treatment. In our cases we use flexible endoscopy and electrocoagulation with better results compared to conventional surgical treatment. Limitations: These are only two cases, but they are rare. Value: Endoscopic treatment with electrocoagulation is shown as an alternative with better results in relation to traditional management for cases of piriform sinus fistula in children.

Indoor and Outdoor Cultures of Gracilaria chilensis: Determination of Biomass Growth and Molecular Markers for Biomass Quality Evaluation.

Taking into consideration climate change scenarios, marine contamination, and a constantly expanding world population, seaweed aquaculture has become an important option for the large-scale production of high-quality biomass. Due to existing biological knowledge of Gracilaria chilensis, several cultivation strategies have been established for obtaining diverse biomolecules (lipids, fatty acids, pigments, among others) with nutraceutical properties. In this research, indoor and outdoor cultivation methodologies were applied to generate high biomass of G. chilensis with positive quality for productive purposes, where the quality was determined according to the concentrations of lipoperoxides and phenolic compounds and the total antioxidant capacity (TAC). The results showed that G. chilensis cultures, which were fertilized for three weeks with Basfoliar® Aktiv (BF) at concentrations of 0.05-1% v/v, obtained high biomass (1-1.3 kg m-2) and DGR (0.35-4.66% d-1), low lipoperoxides (0.5-2.8 µmol g-1 DT), and high phenolic compounds (0.4-0.92 µ eq. GA g-1 FT) and TAC (5-7.5 nmol eq. TROLOX g-1 FT) as compared with other culture media. Lower stress was determined under indoor cultures, due to the operative control of diverse physicochemical stressor parameters (T°, light intensity, photoperiod, among others). Therefore, the cultures developed allow scaling the biomass in productive terms and are suitable for obtaining compounds of interest.

New species of Centris (Xanthemisia) Moure from the Mesoamerican Dominion and the Mexican Transition Zone (Hymenoptera: Apidae).

Three new species of oil-collecting bees of the genus Centris (Xanthemisia) Moure are described and illustrated: C. jakalteka sp. nov., C. maya sp. nov. and C. purhepecha sp. nov. The new proposed taxa are distributed in the north of the Neotropical Region, specifically in the Mesoamerican Dominion and the Mexican Transition Zone, between the Neotropics and Nearctic. In addition, a distribution map and an identification key for the species of the subgenus occurring in the aforementioned regions are also presented.

Xicotli Data: a project to retrieve plant-bee interactions from citizen science.

Background: Xicotli data is the short name given to the dataset generated within the project framework "Integration of Biodiversity Data for the Management and Conservation of Wild Bee-Plant Interactions in Mexico (2021-2023)", as xicotli is the generic word for a bee in Nahuatl. The team comprised eco-informaticians, ecologists and taxonomists of both native bees and flora. The generated dataset contains so far 4,532 curated records of the plants, which are potential hosts of species of three focal families of bees native to Mexico: Apidae, Halictidae and Megachilidae and morphological and ecological data of the plant-bee interactions. This dataset was integrated and mobilised from citizen observations available at naturalista.mx (iNat), which were compiled through the iNaturalist project. New information: The new information obtained with the Xicotli data project was: Taxonomic information about bee species curated by taxonomists based on the information contained in iNaturalist;Taxonomic identification of the host plants by a botanist from the photos compiled by the Xicotli Data project;Data on the ecomorphological traits of bees and plants based on expert knowledge and literature. All the data were integrated into the Xicotli Data Project via the creation of new "observation fields". The visibility of the information originally contained in iNaturalist was maximized and can be consulted directly on the iNaturalist platform.

Heavy Metal Depuration Steps for Gracilaria chilensis in Outdoor Culture Systems.

Seaweed aquaculture is affected by natural and anthropogenic stressors, which put the biomass productivity of the cultures at risk. Seaweed biomass for commercial purposes, principally in pharmaceutical and/or nutraceutical applications, needs to be free of pollutants; therefore, controlled cultures have relevance in regulating the quality of biomass. The aim of this work was to demonstrate the successful utilization of controlled outdoor cultures to remove excess heavy metal accumulation in Gracilaria chilensis, an important commercial seaweed farming model. Specifically, we designed a simple and operational heavy metal depuration protocol, utilizing seawater and tap water removal, which permitted the concentration reduction of 10 heavy metals, including As, Cu, and Cd but not Zn, from the biomass at 7 days of culture. The percentage of depuration of the heavy metals ranged from 32 to 92% at 7 days, which was maintained throughout 21 days of culture. During the culture period, the monitored physicochemical parameters (temperature, salinity, and dissolved oxygen, among others) remained stable, with an increase in the daily growth rate (DGR% d-1) of the biomass recorded after 14 days of culture. Consequently, the experimental setup was successful for heavy metal depuration, which highlights the importance of controlled outdoor cultures as important tools of sustainability.

Revision of carpenter bees of the subgenus Neoxylocopa Michener (Hymenoptera: Apidae) from Mexico and Mesoamerica.

We present a review of the genus Xylocopa (Neoxylocopa) of Mexico and Mesoamerica in which 11 species are recognized, including: X. clarionenis, X. fimbriata, X. frontalis, X. gualanensis, X. mexicanorum, X. nautlana, X. ocellaris, X. sonorina, X. wilmattae. Additionally, two new species are described, X. griswoldi sp. nov. with distribution in the United States and Mexico, and X. maya sp. nov. present in Mexico and Belize. Three species groups within the subgenus Neoxylocopa are recognized: frontalis, mexicanorum and sonorina. Identification keys are presented for identifying species groups and species. Furthermore, images of species and morphological structures as well as information regarding distribution are provided.

¿Día o noche? El momento ideal para realizar la colecistectomía / Day or night? The right time to perform cholecystectomy

Introducción. La frecuencia de complicaciones postquirúrgicas de la colecistectomía realizada en la noche es un tema de controversia, siendo que se ha reportado una frecuencia mayor durante el horario nocturno. El objetivo de este estudio fue analizar la presentación de colecistectomía difícil dependiendo de la hora en que se realizó la cirugía, además de otras complicaciones, estancia intrahospitalaria postquirúrgica, reingreso a 30 días y reintervención. Métodos. Se realizó un estudio retrospectivo, observacional, analítico y transversal, comparando la presentación de colecistectomía difícil y su frecuencia en horario diurno (8:00 am a 7:59 pm) y nocturno (8:00 pm a 7:59 am), además de seroma, absceso, hematoma, fuga biliar, biloma, estancia intrahospitalaria postquirúrgica, reingreso a 30 días y reintervención. Resultados. Se incluyeron en el estudio 228 pacientes, 117 operados durante el día (52 %) y 111 durante la noche (48 %). La colecistectomía difícil se presentó 26 % vs 34 % de los casos intervenidos en el día y la noche, respectivamente. La complicación más frecuente fue seroma (14 %). La estancia hospitalaria media fue de 2,7 días en cirugías diurnas y de 2,5 en cirugías nocturnas; hubo 3 % de reintervenciones y 6 %, respectivamente. También hubo 2 % de reingresos a los 30 días entre los pacientes operados en el día y 3 % entre los operados en la noche. Conclusiones. La frecuencia de colecistectomía difícil y las complicaciones, la estancia intrahospitalaria postquirúrgica, el reingreso a 30 días y la necesidad de reintervención, no tuvieron diferencias significativas respecto al horario de la cirugía.

Introduction. The frequency of post-surgical complications of cholecystectomy performed overnight is a matter of controversy, and a higher rate has been reported during the night shift. The objective of this study was to analyze the presentation of difficult cholecystectomy depending on the time the surgery was performed, in addition to other complications, postoperative hospital stay, 30-day readmission, and reintervention. Methods. A retrospective, observational, analytical and cross-sectional study was carried out, comparing the presentation of difficult cholecystectomy and its frequency during daytime (8:00 am to 7:59 pm) and at night (8:00 pm to 7:59 am), in addition of seroma, abscess, bile leak, biloma, hematoma, post-surgical hospital stay, 30-day readmission, and reintervention.Results. A total of 228 patients were included in the study, 117 patients operated during the day (52%), and 111 at night (48%). Difficult cholecystectomy occurred in 26% vs. 34% of the cases operated on during the day and at night, respectively. The most frequent complication was seroma (14%). The mean hospital stay was 2.7 days in day surgeries and 2.5 in night surgeries; there were also 2% readmission at 30 days among patients operated during the day and 3% among those operated on at night. Conclusions. The frequency of difficult cholecystectomy and complications, postoperative hospital stay, 30-day readmission, and the need of reintervention, did not have significant differences with respect to the time of surgery.

Fístula enteroentérica y enterocutánea asociada a recurrencia de adenocarcinoma de colon / Enteroenteric and enterocutaneous fistula associated with recurrence of colon adenocarcinoma / Fístula enteroentérica e enterocutânea associada à recorrência de adenocarcinoma de cólon

Paciente de sexo femenino de 42 años con antecedente de hemicolectomía derecha por cáncer de colon, con íleo-transverso anastomosis dos años antes. Acudió por dolor abdominal.

The educational quality of the critical view of safety in videos on youtube® versus specialized platforms: which is better? Critical view of safety in virtual resources.

INTRODUCTION: The surgical education has evolved by adopting the visual platforms as a resource of searching. The videos complement the visual learning of surgical techniques of trainees, residents, and surgeons. YouTube® is the most frequently consulted platform in the surgical field. WebSurg® and GIBLIB® are two recognized medical platforms. The Critical View of Safety (CVS) is the most important and effective method to reduce the risk of bile duct injury (BDI) in laparoscopic cholecystectomy (LC). Reaching a satisfactory CVS is a crucial point. We evaluated the CVS of videos on WebSurg® and GIBLIB®, comparing the results with those of the worldwide most popular video platform. METHODS: We performed a search under the term "Laparoscopic cholecystectomy" on the virtual platforms YouTube®, GIBLIB®, and WebSurg®. Three evaluators reviewed the 77 selected videos using the "Sanford-Strasberg' CVS score." The inferential analysis was performed between two groups: YouTube® and Non-YouTube (GIBLIB® and WebSurg®). The characteristics of each video were analyzed including country of origin, type of profile, number of views, and number of Likes. RESULTS: Satisfactory CVS obtained from each of the platforms was GIBLIB® 40%; WebSurg® 44.4%; YouTube® 27.7%. The comparative analysis of CVS quality and CVS score for the Non-YouTube and YouTube® groups did not show a significant difference (p = 0.142, p = 0.377, respectively). CONCLUSION: The videos on GIBLIB® and WebSurg® offer a higher probability of satisfactory CVS compared to YouTube®. Nevertheless, there is no significant superiority of GIBLIB® and WebSurg® over YouTube®.

Transfer of Pollutants from Macrocystis pyrifera to Tetrapygus niger in a Highly Impacted Coastal Zone of Chile.

PAHs and heavy metals are characteristic pollutants in urbanized coastal areas, especially those with industrial activity. Given this context and the ability of Macrocystis pyrifera to drift when detached and provide trophic subsidy in coastal systems, we analyzed the potential transfer of pollutants to the herbivore Tetrapygus niger, through diet, in an industrialized coastal zone in Central Chile (Caleta Horcón) and characterized the impacted zone using diverse polluted ecotoxicological indices. For this purpose, a culture experiment was conducted where M. pyrifera individuals from Algarrobo (control site) were cultivated in Caleta Horcón and then used as food for T. niger. The contents of both PAHs and heavy metal contents were subsequently determined in algal tissue and sea urchin gonads as well as in the seawater. The results show that algae cultivated in Caleta Horcón had higher concentrations of naphthalene (NAF) compared to those from a low industrial impact zone (Algarrobo) (2.5 and 1.8 mg kg-1, respectively). The concentrations of Cu, As, and Cd were higher in Caleta Horcón than in Algarrobo in both M. pyrifera and T. niger. For all metals, including Pb, higher concentrations were present in T. niger than in M. pyrifera (between 5 and 798 times higher). Additionally, as indicated by the toxicological indices MPI (0.00804) and PLI (10.89), Caleta Horcón is highly contaminated with metals compared to Algarrobo (0.0006 and 0.015, respectively). Finally, the bioconcentration factor (BCF) and trophic transfer factor (TTF) values were greater than one in most cases, with values in Caleta Horcón exceeding those in Algarrobo by one or two orders of magnitude. This study provides evidence that Caleta Horcón is a highly impacted zone (HIZ) compared to Algarrobo, in addition to evidence that the biomagnification of certain pollutants, including the possible responses to contaminants, are apparently not exclusively transferred to T. niger through diet.

Negative Consequences on the Growth, Morphometry, and Community Structure of the Kelp Macrocystis pyrifera (Phaeophyceae, Ochrophyta) by a Short Pollution Pulse of Heavy Metals and PAHs.

The study of pollution effects in the marine environment has become important in recent decades, and the exposure to simultaneous pollutants has become especially relevant. Indeed, the study of key organisms, such as ecosystem engineers, can show a broader view of the effects of pollutants. In this context, we evaluate in situ the effects of a short (7-day) pollution pulse of combined solutions of heavy metals and polycyclic aromatic hydrocarbons (PAHs) (Cu + PAHs, Cd + PAHs, Cu + Cd, and Cu + Cd + PAHs) on the development and morphological features of Macrocystis pyrifera sporophytes over a period of 90 days. Additionally, we determined the effects on the community structure associated with this kelp. This study evidenced a smaller number of blades and a decreased size of blades and holdfasts, as well as the death of individuals exposed to a secondary mix of metals (Cu + Cd) and a tertiary mix of pollutants (Cu + Cd + PAHs). Regarding the effects on the accompanying fauna, low richness and diversity were registered. M. pyrifera grazers, according to the mixture of pollutants, were either absent or diminished. These results show that the pulse of contamination in the early stages of M. pyrifera negatively affects its development and morphometry, as well as its role as an ecosystem engineer, due to a negative alteration in the species composition.

T-cell receptor-based therapy: an innovative therapeutic approach for solid tumors.

T-cell receptor (TCR)-based adoptive therapy employs genetically modified lymphocytes that are directed against specific tumor markers. This therapeutic modality requires a structured and integrated process that involves patient screening (e.g., for HLA-A*02:01 and specific tumor targets), leukapheresis, generation of transduced TCR product, lymphodepletion, and infusion of the TCR-based adoptive therapy. In this review, we summarize the current technology and early clinical development of TCR-based therapy in patients with solid tumors. The challenges of TCR-based therapy include those associated with TCR product manufacturing, patient selection, and preparation with lymphodepletion. Overcoming these challenges, and those posed by the immunosuppressive microenvironment, as well as developing next-generation strategies is essential to improving the efficacy and safety of TCR-based therapies. Optimization of technology to generate TCR product, treatment administration, and patient monitoring for adverse events is needed. The implementation of novel TCR strategies will require expansion of the TCR approach to patients with HLA haplotypes beyond HLA-A*02:01 and the discovery of novel tumor markers that are expressed in more patients and tumor types. Ongoing clinical trials will determine the ultimate role of TCR-based therapy in patients with solid tumors.

Cystic neoplasm of the appendix. Report of an unusual clinical case at the South Central High Specialty Hospital PEMEX.

Las neoplasias del apéndice son un grupo heterogéneo de tumores con una incidencia baja, la presentación clínica es inespecífica, cursando generalmente de forma asintomática, y la tomografía es el estudio de elección para el diagnóstico. El tratamiento dependerá del tipo histológico del tumor.The appendix neoplasms are a heterogeneous group of tumors with a low incidence, the clinical presentation is nonspecific, usually being asymptomatic, tomography is the study of choice for the diagnosis. Treatment will depend on the histological type of the tumor.

Coastal pollution from the industrial park Quintero bay of central Chile: Effects on abundance, morphology, and development of the kelp Lessonia spicata (Phaeophyceae).

The industrial park of Quintero Bay (QB) in the central coast of Chile was established in the 1960s, presents high levels of pollution due to the industrial activity, and it is known as one of the five Chilean "sacrifice zones". Lessonia spicata is the most important habitat-forming kelp species in the intertidal along the central and south shores of Chile, and currently there are no morphometric and population studies of L. spicata (or other seaweed species) nor studies about the effects of pollution on its development in QB and neighbouring sites. In this context, the aims of this study were (i) to register the abundance and morphological features of L. spicata populations from Ventanas, Horcón and Cachagua (sites with different pollution histories and located only up to 40 km from the QB); ii) to determine the heavy metals (HMs) concentration in seawater and marine sediments; and (iii) to evaluate in vitro the effects of exposure to seawater from the three sampling sites on spore release and early developmental stages, up to the juvenile sporophyte. Results showed that the chronically exposed Ventanas kelp population had the smallest adult individuals in comparison with the other sites. Ventanas and Horcón registered high HMs concentration in the seawater and marine sediments exceeding the international permissible limits (e.g in seawater Cu 20-859 µg L-1; sediments Cu > 50,000 µg kg-1). Unexpectedly in Cachagua, a site often considered unpolluted, high concentrations of Cu and As were also registered in the seawater (859 and 1,484 µg L-1, respectively) and of As in marine sediments (20,895 µg kg-1). Exposure of gametophytes to the seawater from Ventanas resulted in a developmental delay compared to the other treatments; however, low sporophyte production was determined in all treatments. Our results indicate that QB, more notably Ventanas, induce highly negative effects on individual development, and consequently on seaweed populations, which suggest a long-term negative impact on the community structure of these marine zones. Furthermore, the high concentrations of HMs reported here at Cachagua suggest a recent expansion of pollution along the central coast of Chile, evidencing effects on the marine ecosystem health even on sites far from the pollution source.

Importancia del uso adecuado del equipo de protección individual y la implementación de protocolos de seguridad perioperatorios durante la pandemia de COVID-19 / Importance of the Proper use of Personal Protective Equipment and the Implementation of Perioperative Safety Protocols During the COVID-19 Pandemic

RESUMEN El panorama que se presenta en la actualidad es un reto sin precedentes para el manejo de los pacientes quirúrgicos, la toma de decisiones y el empleo de recursos en cuanto a material y equipos de protección en el contexto de la pandemia por COVID-19. Por lo que el presente artículo pretende dar a conocer los lineamientos para el correcto actuar en el quirófano, el uso del equipo de protección individual, las indicaciones de cirugía y el mejor abordaje en el marco de esta situación. El principal objetivo de seguir estas recomendaciones es mitigar el riesgo de contagio y educar al personal de salud médico-quirúrgico para que esté preparado para hacer frente a esta pandemia.

ABSTRACT The current landscape represents an unprecedented challenge in managing surgical patients, decision-making and the use of resources such as protective equipment in the context of the COVID-19 pandemic. Therefore, the objective of this article is to provide guidelines for good conduct in the operating room, the use of personal protective equipment, suggestions for surgeries and the best approach in the context of this situation. The main objective of these recommendations is to mitigate the risk of contagion and to educate medical-surgical health personnel in how to deal with this pandemic.

Separation of air components and pollutants by the Earth's gravitational field.

In this work, we develop a model able to predict the equilibrium separation of gases due to differences in their molecular weights and the action of gravity. The separation of H, He, O, and N2 with altitude is a characteristic phenomenon of the heterosphere. The model is able to qualitatively recreate the compositional profile of the whole heterosphere from a single composition measurement. The model is applied to the separation of air components and pollutants by empty wells drilled on the planet surface. It predicts that the separation of gases would be possible in wells deep enough under equilibrium. The high molecular weight of some anthropogenic pollutants (SO2, O3, NO2, CO2, etc.) would facilitate their segregation along shorter distances compared to those involved in the heterosphere. The simulations indicate that deep wells could concentrate some air components and pollutants by orders of magnitude over the levels at the Earth's surface without external energy input. For instance, argon molar fractions of >40% and >60% could be achievable at 44 km and 55 km depth, respectively. Finally, we discuss the feasibility of gravitational separation as a potential pollution abatement technology.