Influence of MWCNT/surfactant dispersions on the mechanical properties of Portland cement pastes

This work studies the reinforcing effect of Multi Walled Carbon Nanotubes (MWCNT) on cement pastes. A 0.35% solid concentration of MWCNT in powder was dispersed in deionized water with sodium dodecyl sulfate (cationic surfactant), cetylpyridinium chloride (anionic surfactant) and triton X-100 (amphoteric surfactant) using an ultrasonic tip processor. Three concentrations of each surfactant (1mM, 10mM and 100mM) were tested, and all samples were sonicated until an adequate dispersion degree was obtained. Cement pastes with additions of carbon nanotubes of 0.15% by mass of cement were produced in two steps; first the dispersions of MWCNT were combined with the mixing water using an ultrasonic tip processor to guarantee homogeneity, and then cement was added and mixed until a homogeneous paste was obtained. Direct tensile strength, apparent density and open porosity of the pastes were measured after 7 days of curing. It was found that the MWCNT/surfactants dispersions decrease the mechanical properties of the cement based matrix due to an increased porosity caused by the presence of surfactants. © Published under licence by IOP Publishing Ltd

Tendencias de la investigación en Ingeniería Ambiental

Esta obra incluye las memorias del Simposio “Tendencias de la Investigación en Ingeniería Ambiental”, organizado por el Grupo de Investigaciones y Mediciones Ambientales (GEMA), realizado en la Universidad de Medellín en agosto de 2007. El texto está conformado por 14 capítulos agrupados en cuatro partes. En la primera se agrupan los trabajos relacionados con la calidad y alternativas de tratamiento del agua e hidráulica ambiental (capítulos 1 al 4). La segunda trata temas relacionados con la contaminación atmosférica y calidad del aire (capítulos 5 al 6). La tercera está relacionada con las tecnologías ambientales para la recuperación y conservación de suelos (capítulos 7 al 10) y la cuarta y última comprende las temáticas asociadas con la sostenibilidad ambiental del territorio (capítulos 11 al 14). En este sentido, estamos convencidos del valioso aporte que el libro dará a la comunidad científica, por ser este un documento de divulgación de resultados de investigación en ingeniería ambiental.PRÓLOGO............13 PRESENTACIÓN.............15 PRIMERA PARTE CALIDAD Y ALTERNATIVAS DE TRATAMIENTO DEL AGUA HIDRÁULICA AMBIENTAL Capítulo 1 PRETRATAMIENTO DE AGUAS RESIDUALES INDUSTRIALES MEDIANTE FOTO-FENTON SOLAR A ESCALA INDUSTRIAL ACOPLADO A BIOTRATAMIENTO CON FANGOS ACTIVOS INMOVILIZADOS Manuel Ignacio Maldonado, Isabel Oller, Wolfgang Gernjak, Sixto Malato 1.1 INTRODUCCIÓN............19 1.2 MATERIALES Y MÉTODOS.............21 1.2.1 Reactivos............21 1.2.2 Determinaciones analíticas.............22 1.2.3 Dispositivo experimental.............23 1.3 R ESULTADOS Y DISCUSIÓN............ 27 1.3.1 Tratamiento foto-Fenton solar............27 1.3.2 Biotratamiento mediante fangos activos inmovilizados.............33 1.3.3 Sistema combinado foto-Fenton solar-biológico aeróbico............35 1.4 CONCLUSIONES............. 42 Capítulo 2 DEGRADACIÓN DE LA ATRAZINA EN SOLUCIÓN ACUOSA USANDO RADIACIÓN UV Y PROCESOS DE OXIDACIÓN AVANZADA Margarita Hincapié, Gustavo Peñuela, Manuel I. Maldonado, Sixto Malato 2.1 INTRODUCCIÓN..............47 2.2 SECCIÓN EXPERIMENTAL..............53 2.2.1 Materiales.............53 2.2.2 Metodología...............53 2.2.3 Determinación analítica..............55 2.2.4 Determinación de la toxicidad...............55 2.3 R ESULTADOS Y DISCUSIÓN...............56 2.3.1 Hidrólisis..............56 2.3.2 Fotólisis y fotocatálisis con TiO2 Degussa P25.............56 2.3.3 Efecto de los agentes oxidantes peróxido de hidrógeno y persulfato de sodio en la fotocatálisis..............59 2.3.4 Proceso foto Fenton..............63 2.3.5 Evaluación de los aniones inorgánicos durante los dos tratamientos.............66 2.3.6 Cuantificación e identificación de los productos de degradación...............68 2.3.7 Evaluación de la toxicidad...............71 2.4 CONCLUSIONES...............74 Capítulo 3 HUMEDALES ARTIFICIALES PARA EL TRATAMIENTO DE AGUAS RESIDUALES Nazly E. Sánchez P., Gustavo A. Peñuela M., Juan C. Casas Z. 3.1 INTRODUCCIÓN...............81 3.2 MARCO TEÓRICO...............83 3.2.1 Humedales construidos para el tratamiento de aguas residuales..............84 3.2.2 Clasificación de los humedales.............85 3.2.3 Ventajas y desventajas de los humedales subsuperficiales..............87 3.2.4 Aspectos a considerar en los humedales subsuperficiales..............88 3.3 MATERIALES Y MÉTODOS.................89 3.3.1 Diseño y construcción de los humedales a escala piloto..............89 3.3.2 Componentes del agua residual sintética................90 3.3.3 Siembra y aclimatación de plantas............... 90 3.3.4 Muestreos............91 3.4 R ESULTADOS Y DISCUSIÓN..............91 3.4.1 pH..............91 3.4.2 Demanda bioquímica de oxígeno (DBO5)..............92 3.4.3 Carbono orgánico total (COT)................94 3.5 CONCLUSIONES................95 Capítulo 4 DESCRIPCIÓN DE LA DINÁMICA OCEANOGRÁFICA DEL GOLFO DE URABÁ UTILIZANDO MEDICIONES DE CAMPO Luis Javier Montoya Jaramillo, Francisco Mauricio Toro Botero 4.1 INTRODUCCIÓN...............103 4.2 DATOS Y MÉTODOS................107 4.3 DISCUSIÓN..............118 4.4 CONCLUSIONES............. 120 SEGUNDA PARTE CONTAMINACIÓN ATMOSFÉRICA Y CALIDAD DEL AIRE Capítulo 5 IMPACTO DE LAS MOTOCICLETAS EN LA CALIDAD DEL AIRE. ESTUDIO DE CASO: MONTERÍA Carlos Alberto Echeverri Londoño 5.1 INTRODUCCIÓN.................127 5.2 MATERIALES Y MÉTODOS...............131 5.2.1 S elección de los sitios de medición...............131 5.2.2 Período de medición................131 5.2.3 Parámetros seleccionados...............132 5.2.4 Equipos y materiales utilizados..............132 5.2.5 Índices de calidad del aire..............133 5.2.6 Legislación.............. 138 5.2.7 Inventario de emisiones..............141 5.3 RESULTADOS...............142 5.3.1 Calidad del aire y calidad acústica................142 5.3.2 Emisiones vehiculares.............150 5.3.3 Inventario de emisiones.............155 5.4 CONCLUSIONES.............. 158 5.5 RECOMENDACIONES............. 160 Capítulo 6 ROMPIMIENTO DE LA INVERSIÓN TÉRMICA EN EL VALLE DE ABURRÁ Ángela M. Rendón, José F. Jiménez, Carlos Palacio 6.1 INTRODUCCIÓN...............163 6.2 MEDICIÓN DE VARIABLES ATMOSFÉRICAS..............164 6.3 CAMPAÑAS DE MEDICIÓN.............165 6.4 RESULTADOS..............166 6.5 CONCLUSIONES................170 TERCERA PARTE TECNOLOGÍAS AMBIENTALES PARA LA RECUPERACIÓN Y CONSERVACIÓN DE SUELOS Capítulo 7 ESTRUCTURA MODELO DE LA PARTÍCULA FUNDAMENTAL DEL COMPOST Carlos E. Arroyave M., Carlos A. Peláez J. 7.1 INTRODUCCIÓN..............177 7.2 MATERIALES Y EQUIPOS.............178 7.2.1 Materias primas y planta de compostaje............178 7.2.2 Obtención de fracciones............. 182 7.2.3 Análisis estadístico.............184 7.3 RESULTADOS Y DISCUSIÓN.............184 7.3.1 Caracterización fisicoquímica del material de RSUsf...........184 7.3.2 Tamaño de partícula.............185 7.3.3 Análisis instrumental................187 7.3.4 Modelo de partícula..............194 7.4 CONCLUSIONES..............195 Capítulo 8 DEGRADACIÓN DE HEXACLOROCICLOHEXANO (HCH) CON HONGOS DE PODREDUMBRE DE LA MADERA Juan Carlos Quintero Díaz, Gumersindo Feijoo, Juan Manuel Lema 8.1 INTRODUCCIÓN..............199 8.2 MATERIALES Y MÉTODOS..............204 8.2.1 Microorganismos.............204 8.2.2 Ensayos de selección de los hongos de podredumbre de la madera.............204 8.2.3 Ensayos de degradación de HCH en medio líquido.............205 8.2.4 Ensayos de degradación de HCH en sobre suelo contaminado.............205 8.2.5 Extracción y análisis de los isómeros de HCH.............208 8.3 RESULTADOS Y DISCUSIÓN..............209 8.3.1 Selección de los microorganismos.............209 8.3.2 Degradación de HCH en medio líquido.............210 8.3.3 Degradación de HCH en fase sólida.............212 8.4 CONCLUSIONES.............. 220 Capítulo 9 AVANCES EN LA PROPAGACIÓN ASIMBIÓTICA IN VITRO DE ORQUÍDEAS CON ESPECIAL ÉNFASIS EN EL GÉNERO CATTLEYA Liliana R. Botero, María A. Jaramillo, Óscar O. Ossa R., Tatiana Saldarriaga F., Estefanía Ortiz R. 9.1 INTRODUCCIÓN...............227 9.2 MATERIALES Y MÉTODOS...............231 9.2.1 Evaluación de la metodología de desinfección de cápsulas de orquídeas.............231 9.2.2 Evaluación del efecto de un abono comercial y un suplemento comercial de banano............239 9.3 R ESULTADOS Y DISCUSIÓN..............242 9.3.1 Ensayos de desinfección...............242 9.3.2 Resultados del efecto de un abono comercial y un suplemento de banano comercial....246 9.4 CONCLUSIONES..............254 Capítulo 10 MOVILIDAD DEL BRAVONIL 720 (CLOROTALONILO) A TRAVÉS DE LA ZONA NO SATURADA Y SATURADA DE UN ACUÍFERO LIBRE SIMULADO Idalia Jacqueline López Sánchez, Gustavo Antonio Peñuela Mesa 10.1 INTRODUCCIÓN...............259 10.2 MATERIALES Y MÉTODOS...............261 10.3 RESULTADOS Y DISCUSIÓN..............269 10.4 CONCLUSIONES..............292 CUARTA PARTE SOSTENIBILIDAD AMBIENTAL DEL TERRITORIO Capítulo 11 LA RESPONSABILIDAD SOCIAL EMPRESARIAL COMO COMPONENTE DE SOSTENIBILIDAD AMBIENTAL John Fredy López Pérez 11.1 INTRODUCCIÓN...............299 11.2 UNA LECTURA DE LA SOSTENIBILIDAD AMBIENTAL DESDE UN PUNTO DE VISTA SOCIAL..............300 11.3 EL CONCEPTO DE LA RESPONSABILIDAD SOCIAL EMPRESARIAL...............303 11.4 LA RESPONSABILIDAD SOCIAL COMO ESPACIO PARA L A SOSTENIBILIDAD AMBIENTAL.............309 11.5 ESBOZOS DE UN CASO: EL SECTOR ELÉCTRICO COLOMBIANO..............311 11.6 CONCLUSIONES..............319 Capítulo 12 DETERMINACIÓN ESPACIAL DE ÁREAS DE IMPORTANCIA ESTRATÉGICA El caso de microcuencas abastecedoras de acueductos veredales del municipio de Medellín Joaquín Hincapié, Álvaro Lema 12.1 INTRODUCCIÓN................323 12.2 LA NOCIÓN DE ÁREA DE IMPORTANCIA ESTRATÉGICA...............325 12.3 LA IDEA DE LOS SERV ICIOS AMBIENTALES..............328 12.4 ESTRATEGIA METODOLÓGICA EN LA IDENTIFICACIÓN Y DETERMINACIÓN DE LAS ÁREAS DE IMPORTANCIA ESTRATÉGICA............332 12.5 L OS RESULTADOS DEL MODELO...............359 12.6 CONCLUSIONES............. 361 Capítulo 13 LA EDUCACIÓN AMBIENTAL EN LA TRANSFORMACIÓN DE LA CULTURA Luz Ángela Peña Marín, Alba Miriam Vergara Vargas 13.1 INTRODUCCIÓN..............369 13.2 APROXIMACIÓN CONCEPTUAL...............370 13.2.1 La reflexividad...............372 13.2.2 La construcción del otro...............374 13.2.3 El discurso.............. 372 13.2.4 La autonomía y la participación..............375 13.2.5 La educación ambiental y el desarrollo humano..............378 13.2.6 Base conceptual de la educación ambiental..............380 13.2.7 Contexto sociocultural..............382 13.2.8 Diagnóstico de la educación ambiental y la administración de los recursos naturales..............392 13.2.9 Criterios corporativos de educación ambiental.............394 13.3 CONCLUSIONES...............398 Capítulo 14 ENFOQUE CONCEPTUAL DE UN SISTEMA DE INDICADORES AMBIENTALES PARA LA EVALUACIÓN DE LOS POT: municipios del Valle de San Nicolás Oriente Antioqueño Carolina Arias Muñoz, Diana Elizabeth Valencia Londoño, Boris Puerto López 14.1 INTRODUCCIÓN...............401 14.2 ENFOQUE CONCEPTUAL DEL SISTEMA DE INDICADORES..............406 14.2.1 Primera aproximación: el enfoque de impacto ambiental..............406 14.2.2 Enfoque sistémico: de la sostenibilidad ambiental..............408 14.3 PROPUESTA FINAL DE INDICADORES E ÌNDICE DE SOSTENIBILIDAD AMBIENTAL DEL POT ISAPOT.............424 14.4 R EFLEXIONES FINALES..............42

The phylogeography of trypanosomes from South American alligatorids and African crocodilids is consistent with the geological history of South American river basins and the transoceanic dispersal of Crocodylus at the Miocene

Background: Little is known about the diversity, phylogenetic relationships, and biogeography of trypanosomes infecting non-mammalian hosts. In this study, we investigated the influence of host species and biogeography on shaping the genetic diversity, phylogenetic relationship, and distribution of trypanosomes from South American alligatorids and African crocodilids. Methods: Small Subunit rRNA (SSU rRNA) and glycosomal Glyceraldehyde Phosphate Dehydrogenase (gGAPDH) genes were employed for phylogenetic inferences. Trypanosomes from crocodilians were obtained by haemoculturing. Growth behaviour, morphology, and ultrastructural features complement the molecular description of two new species strongly supported by phylogenetic analyses. Results: The inferred phylogenies disclosed a strongly supported crocodilian-restricted clade comprising three subclades. The subclade T. grayi comprised the African Trypanosoma grayi from Crocodylus niloticus and tsetse flies. The subclade T. ralphi comprised alligatorid trypanosomes represented by Trypanosoma ralphi n. sp. From Melanosuchus niger, Caiman crocodilus and Caiman yacare from Brazilian river basins. T. grayi and T. ralphi were sister subclades. The basal subclade T. terena comprised alligatorid trypanosomes represented by Trypanosoma terena n. sp. from Ca. yacare sharing hosts and basins with the distantly genetic related T. ralphi. This subclade also included the trypanosome from Ca. crocodilus from the Orinoco basin in Venezuela and, unexpectedly, a trypanosome from the African crocodilian Osteolaemus tetraspis. Conclusion: The close relationship between South American and African trypanosomes is consistent with paleontological evidence of recent transoceanic dispersal of Crocodylus at the Miocene/Pliocene boundaries (4–5 mya), and host-switching of trypanosomes throughout the geological configuration of South American hydrographical basins shaping the evolutionary histories of the crocodilians and their trypanosomes.We are grateful to many people who kindly helped us in crocodilian capture\ud and sample collection in Brazil, Venezuela, and Guinea Bissau. We would like\ud to thank Dr. Miguel U. Trefault Rodrigues for the animal identifications. We\ud acknowledge the Brazilian Ministry of Science, Technology and Innovation\ud (MCTI) for support through the Mamirauá Institute for Sustainable\ud Development (IDSM). We thank Cristina Schwartz for the coordination of the\ud work in Guinea Bissau. We also thank Marcio C. Valentin from the Laboratory\ud of Electron Microscopy, Institute of Biosciences, USP, and Carlos E. Jared and\ud Marta M. Antoniazzi from the Institute Butantan, São Paulo, SP, Brazil, for\ud their kindly permission to use their electron microscopic facilities. This work\ud was supported by CNPq (PROAFRICA and PROSUL) and CAPES (Programa\ud Nacional de Incentivo à Pesquisa em Parasitologia Básica). LBV was\ud postdoctoral fellow sponsored by CNPq-MCTI (PROTAX – National Program\ud of Taxonomy) and CAPES (PNPD). BRF is recipient of a scholarship from\ud CNPq (PROTAX)

Niclosamide Prevents the Formation of Large Ubiquitin-Containing Aggregates Caused by Proteasome Inhibition

Protein aggregation is a hallmark of many neurodegenerative diseases and has been linked to the failure to degrade misfolded and damaged proteins. In the cell, aberrant proteins are degraded by the ubiquitin proteasome system that mainly targets short-lived proteins, or by the lysosomes that mostly clear long-lived and poorly soluble proteins. Both systems are interconnected and, in some instances, autophagy can redirect proteasome substrates to the lysosomes.To better understand the interplay between these two systems, we established a neuroblastoma cell population stably expressing the GFP-ubiquitin fusion protein. We show that inhibition of the proteasome leads to the formation of large ubiquitin-containing inclusions accompanied by lower solubility of the ubiquitin conjugates. Strikingly, the formation of the ubiquitin-containing aggregates does not require ectopic expression of disease-specific proteins. Moreover, formation of these focused inclusions caused by proteasome inhibition requires the lysine 63 (K63) of ubiquitin. We then assessed selected compounds that stimulate autophagy and found that the antihelmintic chemical niclosamide prevents large aggregate formation induced by proteasome inhibition, while the prototypical mTORC1 inhibitor rapamycin had no apparent effect. Niclosamide also precludes the accumulation of poly-ubiquitinated proteins and of p62 upon proteasome inhibition. Moreover, niclosamide induces a change in lysosome distribution in the cell that, in the absence of proteasome activity, may favor the uptake into lysosomes of ubiquitinated proteins before they form large aggregates.Our results indicate that proteasome inhibition provokes the formation of large ubiquitin containing aggregates in tissue culture cells, even in the absence of disease specific proteins. Furthermore our study suggests that the autophagy-inducing compound niclosamide may promote the selective clearance of ubiquitinated proteins in the absence of proteasome activity

Temporal variation in black-caiman-nest predation in varzea of central Brazilian amazonia

On the Amazon floodplain, the main predators of black caiman (Melanosuchus niger) eggs are jaguars (Panthera onca), tegu lizards (Tupinambis teguixim), capuchin monkeys (Sapajus macrocephalus) and humans (Homo sapiens). In this study, we investigated the relationship between predator attacks on nests and incubation period, and evaluated the influence of initial predation on subsequent predation in the Mamirauá Sustainable Development Reserve. We also evaluated the influence of presence of females near the nests and manipulation of nests on the occurrence of attacks. We compared results from data obtained with camera traps and vestiges left by predators on estimates of rates of predation by different predators. Egg predation was recorded in 32% of the 658 black caiman nests monitored during two years. Our results suggest that the probability of predation on black caiman eggs is relatively constant throughout the incubation period and that predation on eggs was lower when adults, presumably females, were present. Careful opening of nests and handling of eggs did not increase the number of attacks on black caiman nests. Nest opening by a predator appeared to increase the chances of a subsequent attack because most of the attacks on nests occurred soon after a predator first opened the nest. However, attacks by another species of predator do not appear to be necessary to initiate attacks by any other species of predator. Results based on camera traps and vestiges differed, but use of vestiges was adequate for identifying the principal predators on eggs in black caiman nests and, in many circumstances, the vestiges may be better for estimating predation by humans. In this study, opening nests and handling eggs did not increase the number of attacks on black caiman nests. © 2017 Torralvo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Effect of sitagliptin on cardiovascular outcomes in type 2 diabetes

BACKGROUND: Data are lacking on the long-term effect on cardiovascular events of adding sitagliptin, a dipeptidyl peptidase 4 inhibitor, to usual care in patients with type 2 diabetes and cardiovascular disease. METHODS: In this randomized, double-blind study, we assigned 14,671 patients to add either sitagliptin or placebo to their existing therapy. Open-label use of antihyperglycemic therapy was encouraged as required, aimed at reaching individually appropriate glycemic targets in all patients. To determine whether sitagliptin was noninferior to placebo, we used a relative risk of 1.3 as the marginal upper boundary. The primary cardiovascular outcome was a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for unstable angina. RESULTS: During a median follow-up of 3.0 years, there was a small difference in glycated hemoglobin levels (least-squares mean difference for sitagliptin vs. placebo, -0.29 percentage points; 95% confidence interval [CI], -0.32 to -0.27). Overall, the primary outcome occurred in 839 patients in the sitagliptin group (11.4%; 4.06 per 100 person-years) and 851 patients in the placebo group (11.6%; 4.17 per 100 person-years). Sitagliptin was noninferior to placebo for the primary composite cardiovascular outcome (hazard ratio, 0.98; 95% CI, 0.88 to 1.09; P<0.001). Rates of hospitalization for heart failure did not differ between the two groups (hazard ratio, 1.00; 95% CI, 0.83 to 1.20; P = 0.98). There were no significant between-group differences in rates of acute pancreatitis (P = 0.07) or pancreatic cancer (P = 0.32). CONCLUSIONS: Among patients with type 2 diabetes and established cardiovascular disease, adding sitagliptin to usual care did not appear to increase the risk of major adverse cardiovascular events, hospitalization for heart failure, or other adverse events

Laparoscopy in management of appendicitis in high-, middle-, and low-income countries: a multicenter, prospective, cohort study.

BACKGROUND: Appendicitis is the most common abdominal surgical emergency worldwide. Differences between high- and low-income settings in the availability of laparoscopic appendectomy, alternative management choices, and outcomes are poorly described. The aim was to identify variation in surgical management and outcomes of appendicitis within low-, middle-, and high-Human Development Index (HDI) countries worldwide. METHODS: This is a multicenter, international prospective cohort study. Consecutive sampling of patients undergoing emergency appendectomy over 6 months was conducted. Follow-up lasted 30 days. RESULTS: 4546 patients from 52 countries underwent appendectomy (2499 high-, 1540 middle-, and 507 low-HDI groups). Surgical site infection (SSI) rates were higher in low-HDI (OR 2.57, 95% CI 1.33-4.99, p = 0.005) but not middle-HDI countries (OR 1.38, 95% CI 0.76-2.52, p = 0.291), compared with high-HDI countries after adjustment. A laparoscopic approach was common in high-HDI countries (1693/2499, 67.7%), but infrequent in low-HDI (41/507, 8.1%) and middle-HDI (132/1540, 8.6%) groups. After accounting for case-mix, laparoscopy was still associated with fewer overall complications (OR 0.55, 95% CI 0.42-0.71, p < 0.001) and SSIs (OR 0.22, 95% CI 0.14-0.33, p < 0.001). In propensity-score matched groups within low-/middle-HDI countries, laparoscopy was still associated with fewer overall complications (OR 0.23 95% CI 0.11-0.44) and SSI (OR 0.21 95% CI 0.09-0.45). CONCLUSION: A laparoscopic approach is associated with better outcomes and availability appears to differ by country HDI. Despite the profound clinical, operational, and financial barriers to its widespread introduction, laparoscopy could significantly improve outcomes for patients in low-resource environments. TRIAL REGISTRATION: NCT02179112

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe