Metal-Organic Frameworks as Formose Reaction Catalysts with Enhanced Selectivity.

The formose reaction is an autocatalytic series of aldol condensations that allows one to obtain monosaccharides from formaldehyde. The formose reaction suffers from a lack of selectivity, which hinders practical applications at the industrial level. Over the years, many attempts have been made to overcome this selectivity issue, with modest results. Heterogeneous porous catalysts with acid-base properties, such as Metal-Organic Frameworks (MOFs), can offer advantages compared to homogeneous strong bases (e.g., calcium hydroxide) for increasing the selectivity of this important reaction. For the very first time, four different Zeolite Imidazolate Frameworks are presented in this work as catalysts for the formose reaction in liquid phase, and their catalytic performances were compared with those of the typical homogeneous catalyst (i.e., calcium hydroxide). The heterogeneous nature of the catalysis, the possible contribution of leached metal or linkers to the solution, and the stability of the materials were investigated. The porous structure of these solids and their mild basicity make them suitable for obtaining enhanced selectivity at 30% formaldehyde conversion. Most of the MOFs tested showed low structural stability under reaction conditions, thereby indicating the need to search for new MOF families with higher robustness. However, this important result opens the path for future research on porous heterogeneous basic catalysts for the formose reaction.

Improved Thermochemical Energy Storage Behavior of Manganese Oxide by Molybdenum Doping.

To improve the thermochemical energy storage (TCS) behavior of Mn2O3, several Mn-Mo oxides with varying amounts of MoO3 (0-30 wt%) were prepared by a precipitation method. The physico-chemical properties of the solids were studied by N2 adsorption-desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and H2-temperature-programmed reduction (TPR), while their TCS behavior was determined by thermogravimetric analysis coupled with differential scanning calorimetry (TGA-DSC). Apart from Mn2O3 and MoO3 phases, XRD revealed a mixed MnMoO4 phase for MoO3 loadings equal or higher than 1.5 wt%. All samples showed a well-formed coral-like surface morphology, particularly those solids with low MoO3 contents. This coral morphology was progressively decorated with compact and Mo-enriched MnMoO4 particles as the MoO3 content increased. TPR revealed that the redox behavior of Mn2O3 was significantly altered upon addition of Mo. The TCS behavior of Mn2O3 (mostly oxidation kinetics and redox cyclability) was enhanced by addition of low amounts of Mo (0.6 and 1.5% MoO3) without significantly increasing the reduction temperature of the solids. The coral morphology (which facilitated oxygen diffusion) and a smoother transition from the reduced to oxidized phase were suggested to be responsible for this improved TCS behavior. The samples containing 0.6 and 1.5 wt% of MoO3 showed outstanding cyclability after 45 consecutive reduction-oxidation cycles at high temperatures (600-1000 °C). These materials could potentially reach absorption efficiencies higher than 90% at concentration capacity values typical of concentrated solar power plants.

Catalytic Production of Jet Fuels from Biomass.

Concerns about depleting fossil fuels and global warming effects are pushing our society to search for new renewable sources of energy with the potential to substitute coal, natural gas, and petroleum. In this sense, biomass, the only renewable source of carbon available on Earth, is the perfect replacement for petroleum in producing renewable fuels. The aviation sector is responsible for a significant fraction of greenhouse gas emissions, and two billion barrels of petroleum are being consumed annually to produce the jet fuels required to transport people and goods around the world. Governments are pushing directives to replace fossil fuel-derived jet fuels with those derived from biomass. The present mini review is aimed to summarize the main technologies available today for converting biomass into liquid hydrocarbon fuels with a molecular weight and structure suitable for being used as aviation fuels. Particular emphasis will be placed on those routes involving heterogeneous catalysts.

Post-Harvest Behavior of Seedless Conical and Mini-Conical Peppers: Weight Loss, Dry Matter Content, and Total Soluble Solids as Indicators of Quality and Commercial Shelf-Life.

This study aimed to assess the post-harvest dynamics of seedless conical and mini-conical pepper cultivars in terms of fruit weight loss, dry matter content, and soluble solid content. The above parameters were demonstrated to be effective commercial pepper shelf-life indicators. The commercial quality of pepper fruit intended for export was evaluated weekly under simulated fruit storage conditions for over 28 d. Results revealed that fruit weight loss, dry matter content, and soluble solid content were affected by cultivar type and storage duration. Additionally, a strong correlation between these variables was observed confirming their linear relationship which was more profound between dry matter and total soluble solid content. Daily changes during storage were similar in both seedless conical and mini-conical peppers, while the fruit weight loss daily rate was greater than that of dry matter. Water loss was identified to be the main factor causing reduced fruit quality. Solid content reduction occurred predominately during the initial storage period. Notably, fruit with lower dry matter content at harvest tended to maintain their commercial quality for a longer time due to their ability to resist water loss without any visible signs of deterioration, which is beneficial during prolonged storage.

A Conceptual Approach for the Design of New Catalysts for Ammonia Synthesis: A Metal-Support Interactions Review.

The growing interest in green ammonia production has spurred the development of new catalysts with the potential to carry out the Haber-Bosch process under mild pressure and temperature conditions. While there is a wide experimental background on new catalysts involving transition metals, supports and additives, the fundamentals behind ammonia synthesis performance on these catalysts remained partially unsolved. Here, we review the most important works developed to date and analyze the traditional catalysts for ammonia synthesis, as well as the influence of the electron transfer properties of the so-called 3rd-generation catalysts. Finally, the importance of metal-support interactions is highlighted as an effective pathway for the design of new materials with potential to carry out ammonia synthesis at low temperatures and pressures.

Facile Synthesis of Heterogeneous Indium Nanoparticles for Formate Production via CO2 Electroreduction.

In this study, a simple and scalable method to obtain heterogeneous indium nanoparticles and carbon-supported indium nanoparticles under mild conditions is described. Physicochemical characterization by X-ray diffraction (XRD), X-ray photoelectron microscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed heterogeneous morphologies for the In nanoparticles in all cases. Apart from In0, XPS revealed the presence of oxidized In species on the carbon-supported samples, whereas these species were not observed for the unsupported samples. The best-in-class catalyst (In50/C50) exhibited a high formate Faradaic efficiency (FE) near the unit (above 97%) at -1.6 V vs. Ag/AgCl, achieving a stable current density around -10 mA·cmgeo-2, in a common H-cell. While In0 sites are the main active sites for the reaction, the presence of oxidized In species could play a role in the improved performance of the supported samples.

Risk of musculoskeletal disorders in pepper cultivation workers.

Agricultural workers have an increased risk of musculoskeletal disorders, mainly due to the manual nature of the work. This study assesses the level of physical well-being in pepper cultivation workers in Almería (Spain). The objective was to analyze pepper cultivation tasks performed in the Almería-type greenhouse, using the OWAS (Ovako Working Posture Assessment System) and RULA (Rapid Upper Limb Assessment) methods. The OWAS results showed a normal posture percentage of 53 %, a medium risk of 30 %, a high risk of 16 %, and a very high risk of 1 %. The body areas most affected were the back and legs. The RULA assessment found high risk/action levels, with 50 % of the postures corresponding to level 3, 35 % to level 4, and 15 % to level 2. Improvements are therefore proposed; these include: redesigning tasks, mechanization, training, team development, and improving the workers' physical condition. The OWAS and RULA data may have overestimated the results, as workers do not appear to be limited in performing tasks and do not normally request sick leave.

An Overview of REBA Method Applications in the World.

The objective of this work is to review literature, worldwide, in which the Rapid Entire Body Assessment (REBA) ergonomic assessment method was applied and count the number of times that REBA was applied together with other methods and subsequent incidence. The database used was the "Web of Science-Core Collection". Only scientific articles and bibliographic reviews were included, analysing a total of 314 documents and selecting only 91. The use of the REBA method is indicated in terms of knowledge, country, year and journal sectors. It was most used in the knowledge areas of "Manufacturing" (24.18%), "Agriculture, forestry and fishing" (21.98%) and in "Other activities" (19.78%). One of the benefits of REBA is that it evaluates different body parts: upper limbs (arm, forearm and wrist), lower extremities, trunk and neck. It is a useful method to identify the forced postures adopted by workers to thus develop improvement measures if necessary. It is concluded that REBA method use has increased over the last decade, probably due to the digitization of knowledge. It is almost always applied in combination with other methods, and its use can be a positive indicator of company sustainability.

Musculoskeletal Risks: RULA Bibliometric Review.

The objective of this study was to reveal RULA method applications in terms of the knowledge, country, year and journal categories. The search was performed using the "Web of Science Core Collection". The period from 1993 to April 2019 was selected. Eight hundred nine results were obtained, of which 226 were used. The largest number of publications was determined to be in the fields of industry and health and social assistance, which coincides with the OWAS and Standardized Nordic Questionnaire methods. By country, the USA stands out for its greater number of research studies and categories that are encompassed. By date, 2016 was the year when more studies were carried out, again coinciding with the Standardized Nordic Questionnaire. By journal, "Work-A Journal of Prevention Assessment and Rehabilitation" is highlighted, as it is for the REBA method as well. It was concluded that RULA can be applied to workers in different fields, usually in combination with other methods, while technological advancement provides benefits for its application.

Interplay of Support Chemistry and Reaction Conditions on Copper Catalyzed Methanol Steam Reforming.

A series of Cu catalysts supported on SiO2, Al2O3-SiO2, TiO2 rutile, and Cu/TiO2 anatase metal oxides has been studied for methanol reforming in the vapor phase. The highest activity was obtained on Cu/SiO2 catalysts (5493 µmol H2 min-1·gcat -1) followed by Cu/TiO2 rutile, Cu/Al2O3-SiO2, and anatase. XRD and HRTEM characterization after reaction revealed that on Cu/SiO2 significant sintering occurred during reaction. In contrast, the particle size growth on Cu/TiO2 rutile and anatase was less pronounced, which could be associated with the interaction between Cu clusters and TiO2. Characterization by TGA showed that on Cu/Al2O3-SiO2 the main cause of deactivation was coke deposition.

Detección de enfermedad renal crónica oculta mediante determinación de albuminuria en pacientes con diabetes mellitus / Detection of Hidden Chronic Kidney Disease by Determining Albumin Estimates in Patients with Diabetes Mellitus

Introducción: La diabetes mellitus constituye la segunda causa de enfermedad renal crónica en Cuba. La estimación de albuminuria facilitaría la identificación precoz de esta. Objetivo: Determinar el valor predictor de enfermedad renal crónica oculta en la albuminuria de pacientes con diabetes mellitus de la Atención Primaria de Salud en Las Tunas. Métodos: Se realizó un estudio analítico de caso-control en 360 pacientes con diabetes mellitus pertenecientes al Policlínico Manuel Fajardo Rivero, en el período de enero de 2019 a febrero de 2020. La población en estudio fue dividida en dos grupos, atendiendo a la presencia (casos) o no (controles) de daño renal. El poder discriminatorio de la albuminuria como predictor de enfermedad renal crónica oculta se determinó mediante el área bajo la curva ROC, además se identificó el punto de corte óptimo. Se utilizó el análisis multivariado para identificar los factores predictores independientes de enfermedad renal. Resultados: La albuminuria mayor de 160 mg/24h fue identificada como predictor de enfermedad renal crónica oculta (OR: 2,278; IC de 95 por ciento: 1,637-2,908) junto a la edad ˃ 65 años, los años de evolución de DM ˃ 8 años y la hipoalbuminemia. El poder discriminatorio fue bueno, índice C: 0,843 (IC de 95 por ciento: 0,762-0,929). El punto de corte identificado de 160 mg/24h alcanzó una sensibilidad y especificidad de 90,00 por ciento y 97,60 por ciento, respectivamente. Conclusiones: La albuminuria pudiese ser un importante predictor independiente de enfermedad renal crónica oculta en pacientes con diabetes mellitus de la Atención Primaria de Salud(AU)

Introduction: Diabetes mellitus is the second cause of chronic kidney disease in Cuba. Albumin estimates would facilitate its early identification. Objective: To determine the predictive value of albuminuria in hidden chronic kidney disease among patients with diabetes mellitus at primary healthcare level in Las Tunas. Methods: An analytical case-control study was carried out in 360 patients with diabetes mellitus belonging to Manuel Fajardo Rivero Polyclinic, in the period from January 2019 to February 2020. The study population was divided into two groups: occurrence (cases) or not (controls) of kidney damage. The discriminatory power of albuminuria as a predictor of hidden chronic kidney disease was determined by the area under the ROC curve, while its optimal cut-off point was also identified. Multivariate analysis was used to identify independent predictors of kidney disease. Results: Albuminuria over 160 mg on 24 hours was identified as a predictor of hidden chronic kidney disease (OR: 2.278; 95 percent CI: 1.637-2.908) together with age over 65 years, evolution of diabetes mellitus over 8 years, and hypoalbuminemia. The discriminatory power was good: The C index was 0.843 (95 percent CI: 0.762-0.929). The identified cut-off point of 160 mg in 24 hours reached a sensitivity and specificity of 90.00 percent and 97.60 percent, respectively. Conclusions: Albuminuria could be an important independent predictor of hidden chronic kidney disease in patients with diabetes mellitus at primary healthcare level(AU)

[Susceptibility of Aedes aegypti (L.) strains from Havana to a Bacillus thuringiensis var. israelensis]. / Susceptibilidad de cepas de Aedes aegypti (L.) a Bacillus thuringiensis var. israelensis en La Habana.

INTRODUCTION: the integration of chemical and biological methods is one of the strategies for the vector control, due to the existing environmental problems and the concerns of the community as a result of the synthetic organic insecticide actions. The bacterium called Bacillus thuringiensis var. israelensis in liquid formulation has been widely used in the vector control programs in several countries and has shown high efficacy at lab in Cuba. OBJECTIVE: to determine the susceptibility of Aedes aegypti collected in the municipalities of La Habana province to Bacillus thuringiensis var. israelensis. METHODS: fifteen Aedes aegypti strains, one from each municipality, were used including larvae and pupas collected in 2010 and one reference strain known as Rockefeller. The aqueous formulation of Bacillus thuringiensis var. israelensis (Bactivec, Labiofam, Cuba) was used. The bioassays complied with the World Health Organization guidelines for use of bacterial larvicides in the public health sector. The larval mortality was read after 24 hours and the results were processed by the statistical system SPSS (11.0) through Probit analysis. RESULTS: the evaluated mosquito strains showed high susceptibility to biolarvicide, there were no significant differences in LC50 values of Ae. aegypti strains, neither in the comparison of these values with those of the reference strain. CONCLUSIONS: the presented results indicate that the use of Bacillus thuringiensis var. israelensis continues to be a choice for the control of Aedes aegypti larval populations in La Habana province.

[Influence of biotic factors on the efficacy of Bacillus thuringiensis var. Israelensis against Aedes aegypti (Diptera: Culicidae)]. / Influencia de factores bióticos sobre la eficacia de Bacillus thuringiensis var. israelensis contra Aedes aegypti (Diptera: Culicidae).

INTRODUCTION: Bacillus thuringiensis H-14 has shown high efficacy on Aedes aegypti larvae. But a number of factors could affect its effectiveness. Knowing these factors is of vital importance for improving the application parameters in real conditions in order to guarantee the treatment's efficiency and to reduce environmental impact. OBJECTIVE: to evaluate the influence of some biotic factors on Bacillus thuringiensis H-14 efficacy against Aedes aegypti (Rockefeller). METHODS: an experimental study was conducted following the WHO guidelines. The influence of the food availability, the larval density and the larval staging was evaluated on laboratory bioassays. A commercial Bacillus thuringiensis H-14 formulation against a reference Aedes aegypti strain was used. RESULTS: the efficacy of Bacillus thuringiensis H-14 decreased in a linear manner with increasing larval density and development stage. This could be related to food intake and availability of the active principle. Competition in food intake resulted in lower efficacy of Bacillus thuringiensis H-14 applications. CONCLUSIONS: the Bacillus thuringiensis H-14 efficacy was affected for the availability of food, the larval development stage and the larval density, so all this should be borne in mind when applying the biolarvicide in situ.

Improving the climate safety of workers in Almería-type greenhouses in Spain by predicting the periods when they are most likely to suffer thermal stress.

The humidex and wind-chill indices were used to determine the periods in which labourers working in Almería-type greenhouses in southeastern Spain are most likely to suffer conditions able to induce heat and cold stress. Over 500,000 pieces of data for wet and dry bulb temperatures and relative humidity, recorded over a period in excess of five years by a weather station located in an Almería-type greenhouse containing a grass crop, were used in the calculation of these indices. The wind-chill index results showed cold stress never to be a problem, but the humidex index results showed that conditions under which heat stress could develop were common in the warmer months. A clock diagram was produced showing the hours when heat stress is likely to occur in each month of the year. This information could be used to improve the conditions of labourers working in this type of greenhouse; some ways of reducing their exposure to heat stress-inducing conditions are discussed.

Evaluación de tres dietas alimentarias para el período larval de Aedes aegypti en condiciones de laboratorio / Assessment of three feeding diets for the Aedes aegypti larval stage under lab conditions

Introducción: la alimentación en el período larval del mosquito es sumamente importante, debido a que en esta etapa almacenan los nutrientes básicos para el desarrollo de la pupa y el adulto. Objetivo: evaluar la calidad de tres dietas como fuente nutritiva y su influencia en el desarrollo de las fases preadultas de Aedes aegypti. Métodos: se evaluaron tres dietas en el insectario del Instituto Pedro Kourí, concentrado CENPALAB, elaborado en el Centro para la Producción de Animales de Laboratorio (CENPALAB), levadura torula, subproducto de la caña de azúcar (ambas de producción nacional) y harina de pescado, producto de importación. Previamente, se determinó la calidad higiénica-microbiológica y química nutricional de las dietas. Se evaluaron variables biológicas como el número de pupas diarias por alimentos y la duración del ciclo larval; se determinó la cantidad de proteínas presentes en las larvas alimentadas con cada dieta, mediante el método de Lowry. Resultados: la calidad higiénica-microbiológica, así como la caracterización química nutricional de los 3 alimentos evaluados, aportaron resultados satisfactorios para el desarrollo de la investigación. Los valores mayores en la concentración de proteínas y en la actividad biológica en la fase larval del mosquito se obtuvieron con la harina de pescado. No se encontraron diferencias significativas en la concentración de proteínas entre las dietas en los primeros días del período larval, A partir del quinto hasta el séptimo día de vida, la harina de pescado fue superior al concentrado CENPALAB. La emergencia de pupas comenzó al sexto día para todas las dietas, obteniéndose el pico más alto al séptimo día con diferencias entre estas. El ciclo larval duró de 7 a 8 días. Conclusiones: se sugiere la utilización de las dietas de producción nacional en situaciones que lo requieran por carencia de la dieta importada, para no detener el desarrollo de las investigaciones

Introduction: feeding mosquitoes during the larval stage is an important process, since it is the stage in which basic nutrients are stored for the subsequent development of pupas and adults. Objective: to evaluate both the quality of three diets as nutritional source and the influence these diets have on the development of the Aedes aegypti in its pre-adult stage. Methods: three different diets were evaluated at the Insectarium of the Pedro Kourí Tropical Medicine Institute in Havana, Cuba. The diets evaluated were: CENPALAB Food Concentrate, elaborated at the Center for Laboratory Animal Production (CENPALAB, Spanish acronym) and torula yeast, a sugar cane byproduct (both of them from domestic production) as well as fish flour, an imported product

[Conduct of the oviposition of Aedes aegypti (L.) in the presence of Macrocyclops albidus (J.) and Bacillus thuringiensis var. israelensis under lab conditions]. / Conducta de oviposición de Aedes aegypti (L.) en presencia de Macrocyclops albidus (J.) y Bacillus thuringiensis var. israelensis en condiciones de laboratorio.

The behaviour of the oviposition of pregnant females of Aedes aegypti in the presence of biological agents: Macrocyclops albidus (Copepoda: Cyclopoidea) or Bacillus thuringiensis var. israelensis (Bti) was evaluated under lab conditions. Recipients containing 225 mL of dechlorinated water were placed for oviposition with three variants: water with copepods, water with Bti, and water. The average of eggs layed in the recipients with copepods and Bti were 1 227.9 and 1 200.8, respectively, a figure higher than the 887.4 eggs of the recipient containing only water, although the differences observed were not statistically significant (p > 0.05). The Oviposotion Activity Index (OAI) estimated showed values over 0 for copepods and for Bti, which indicated that females did not avoid to deposit their eggs in these recipients. The results suggested that in nature, these recipients with biological controllers may be oviposition sites for pregnant females of Aedes aegypti, which may have positive implications on its effectiveness to control this vector.

Influencia de factores bióticos sobre la eficacia de Bacillus thuringiensis var. israelensis contra Aedes aegypti (Diptera: Culicidae) / Influence of biotic factors on the efficacy of Bacillus thuringiensis var. Israelensis against Aedes aegypti (Diptera: Culicidae)

Introducción: Bacillus thuringiensis H-14 ha mostrado alta eficacia sobre las larvas de Aedes aegypti, pero su efectividad puede ser influida por numerosos factores. El conocimiento de estos es de gran importancia porque permite optimizar los parámetros de aplicación en condiciones reales, para garantizar la eficiencia de los tratamientos y reducir el impacto ambiental. Objetivo: evaluar la influencia de los factores bióticos sobre la eficacia de Bacillus thuringiensis H-14 contra las larvas de Aedes aegypti. Métodos: se realizó un estudio experimental mediante bioensayos de laboratorio, siguiendo la metodología de la Organización Mundial de la Salud. Se evaluó la influencia de la disponibilidad de alimento, densidad y estadio larvario sobre la eficacia de Bacillus thuringiensis H-14 para Aedes aegypti. Se utilizó un biolarvicida comercial (Bactivec, Labiofam) y una cepa de referencia de Aedes aegypti (Rockefeller). Resultados: la eficacia de Bacillus thuringiensis H-14 fue menor en la medida en que avanzó la densidad y el estadio de desarrollo larvario, lo que puede estar en relación con la conducta de alimentación y la disponibilidad del principio activo. La presencia abundante de alimento también limita la eficacia por un efecto de competencia. Conclusiones: la eficacia de Bacillus thuringiensis H-14 se afectó por la disponibilidad de alimento, el estadio de desarrollo y la densidad larvaria, por lo que debe tenerse en cuenta esto para las aplicaciones del biolarvicida en el terreno.

Introduction: Bacillus thuringiensis H-14 has shown high efficacy on Aedes aegypti larvae. But a number of factors could affect its effectiveness. Knowing these factors is of vital importance for improving the application parameters in real conditions in order to guarantee the treatment's efficiency and to reduce environmental impact. Objective: to evaluate the influence of some biotic factors on Bacillus thuringiensis H-14 efficacy against Aedes aegypti (Rockefeller). Methods: an experimental study was conducted following the WHO guidelines. The influence of the food availability, the larval density and the larval staging was evaluated on laboratory bioassays. A commercial Bacillus thuringiensis H-14 formulation against a reference Aedes aegypti strain was used. Results: the efficacy of Bacillus thuringiensis H-14 decreased in a linear manner with increasing larval density and development stage. This could be related to food intake and availability of the active principle. Competition in food intake resulted in lower efficacy of Bacillus thuringiensis H-14 applications. Conclusions: the Bacillus thuringiensis H-14 efficacy was affected for the availability of food, the larval development stage and the larval density, so all this should be borne in mind when applying the biolarvicide in situ.

Estudio de resistencia de Aedes aegypti a Bacillus thuringiensis var: israelensis / Study of Aedes aegypti resistance to Bacillus thuringiensis var: israelensis

Introducción: el uso prolongado de insecticidas ha conducido al desarrollo de resistencia en diferentes especies de mosquitos incluido el Aedes aegypti, aunque hasta el momento no existen reportes de resistencia a Bacillus thuringiensis var. israelensis. Objetivos: evaluar la resistencia a Bacillus thuringiensis var. israelensis en poblaciones de Aedes aegypti provenientes de sitios donde se ha aplicado la formulación líquida Bactivec (Labiofam) y en cepas de laboratorio bajo presión de selección. Métodos: se realizaron colectas de larvas en 3 municipios de Ciudad de La Habana y se establecieron las colonias de Aedes aegypti en el laboratorio, las cuales se compararon en susceptibilidad a Bacillus thuringiensis con la cepa de referencia Rockefeller. El experimento de selección se realizó exponiendo generaciones sucesivas de una cepa susceptible a la dosis letal 90 del biolarvicida. Resultados: el índice de resistencia 50 para las cepas de los municipios Plaza, Cerro y Boyeros fue de 1,07, 0,66 y 0,81, respectivamente, por lo cual pueden considerarse susceptibles. La cepa expuesta a intensa presión de selección con el biolarvicida mostró índices de resistencia 50 y 95 de 2,7 y 4,6, respectivamente. La menor pendiente de la línea de regresión correspondió a la cepa bajo selección, lo que indica mayor variabilidad genética de esta población. Conclusiones: estos resultados justifican la utilización de Bacillus thuringiensis var. israelensis como una alternativa para el control de estadios inmaduros de Aedes aegypti sin que exista evidencia hasta el presente de aparición de resistencia en poblaciones de campo, pero deben trazarse estrategias de manejo adecuadas ante la potencialidad del vector de adquirirla.

Introduction: Prolonged use of insecticides has led to resistance development in different mosquito species including Aedes aegypti, although there is no report of resistance to Bacillus thuringiensis var. israelensis so far. Objectives: To evaluate resistance to Bacillus thuringiensis var. israelensis in Aedes aegypti populations from places where fluid preparation Bactivec (made in Labiofam company) has been applied, and in lab strains under selection. Methods: Larvae were collected in three municipalities of the City of Havana province to settle Aedes aegypti colonies in the laboratory, which were compared with reference strain called Rockefeller in terms of susceptibility to Bacillus thuringiensis. The selection experiment was performed by exposing successive generations of a strain susceptible to lethal dose 90 of this biolarvicide. Results: Resistance index 50 for strains from Plaza, Cerro and Boyeros was 1.07, 0.66 and 0.81 respectively, so they may be considered as susceptible strains. The strain exposed to intensive selection pressure with the biolarvicide showed resistance indexes 50 and 95 equal to 2.7 and 4.6 respectively. The smallest regression line slope was found in the selection strain, which indicated a greater genetic variability in this population. Conclusions: these results support the use of Bacillus thuringiensis var. Israelensis as an alternative for management of immature Aedes aegyptis without any evidence whatsoever of emerging resistance in the field population, but some adequate management strategies should be drawn, taking into account the vector´s potentialities to acquire it.

Conducta de oviposición de Aedes aegypti (L.) en presencia de Macrocyclops albidus (J.) y Bacillus thuringiensis var. israelensis en condiciones de laboratorio / Conduct of the oviposition of Aedes aegypti (L.) in the presence of Macrocyclops albidus ( J.), and Bacillus thuringiensis var. israelensis under lab conditions

Se evaluó la conducta de oviposición de hembras grávidas de Aedes aegypti en presencia de los agentes biológicos: Macrocyclops albidus (Copepoda: Cyclopoidea) o Bacillus thuringiensis var. israelensis (Bti) en condiciones de laboratorio. Se colocaron recipientes con 225 mL de agua declorada para la puesta de huevos con 3 variantes: agua con copépodos, agua con Bti y agua. El promedio de huevos depositados en los recipientes con copépodos y Bti fueron de 1 227,9 y 1 200,8 respectivamente, superiores al de 887,4 huevos del recipiente que contenía solo agua, aunque las diferencias observadas no fueron estadísticamente significativas (p> 0,05). Los Indices de la Actividad de Oviposición (IAO) calculados mostraron valores mayores que 0 para copépodos y para Bti, indicando que las hembras no evitaron ovipositar en estos recipientes. Los resultados sugieren que en la naturaleza los recipientes que contienen estos controladores biológicos pudieran constituir sitios para la oviposición de hembras grávidas de Aedes aegypti, lo que tendría implicaciones positivas en su eficacia para controlar este vector.

The behaviour of the oviposition of pregnant females of Aedes aegypti in the presence of biological agents: Macrocyclops albidus (Copepoda: Cyclopoidea) or Bacillus thuringiensis var. israelensis (Bti) was evaluated under lab conditions. Recipients containing 225 mL of dechlorinated water were placed for oviposition with three variants: water with copepods, water with Bti, and water. The average of eggs layed in the recipients with copepods and Bti were 1 227.9 and 1 200.8, respectively, a figure higher than the 887.4 eggs of the recipient containing only water, although the differences observed were not statistically significant (p >0.05). The Oviposotion Activity Index (OAI) estimated showed values over 0 for copepods and for Bti, which indicated that females did not avoid to deposit their eggs in these recipients. The results suggested that in nature, these recipients with biological controllers may be oviposition sites for pregnant females of Aedes aegypti, which may have positive implications on its effectiveness to control this vector.

Enfoque clínico-etiológico de las cefaleas / Clinical and etiological approach to headache

Las cefaleas constituyen una de las dolencias médicas más frecuentes en las consultas de neurología. Si tenemos en cuenta que afecta entre el 50 y el 60 porciento de la población en uno u otro período de la vida, y que entre el 8 y el 10 porciento requiere tratamiento médico por este motivo, veremos que es necesario que los médicos tengan un conocimiento preciso de sus diversas etiologías, su diagnóstico y tratamiento. En el presente trabajo, destinado a brindar información sobre las cefaleas a los médicos del nivel primario de atención en salud pública, se realiza una revisión de las principales etiologías de las cefaleas, haciendo énfasis en las cefalalgias primarias