Results: 31
#1
au:Parra, R. L.
Filters
Order by
Page
of 3
Next
1.
Sowing date changes phenological development, plastochron index, and grain yield of soybeans under Cerrado conditions
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Bossolani, João W.
; Meneghette, Hugo H. A.
; Sanches, Izabela R.
; Santos, Fabiana L. dos
; Parra, Lucas F.
; Lazarini, Edson
.
Revista Brasileira de Engenharia Agrícola e Ambiental
- Journal Metrics
RESUMO A época de semeadura é a prática de manejo cultural com maior interferência no desenvolvimento e na produtividade de grãos de soja, e está diretamente relacionada com o genótipo e tipo de ciclo da cultura. Nosso objetivo foi avaliar o desenvolvimento fenológico em função das respostas fotoperíodicas, índice de plastocrono e produtividade de grãos de três cultivares de soja com ciclos diferentes, semeadas em três épocas distintas O estudo foi realizado em Sevíria, Mato Grosso do Sul e utilizou um delineamento de parcelas subdivididas com as parcelas principais dispostas em blocos com quatro repetições. As parcelas foram compostas por três épocas de semeadura com intervalo de 15 dias, a partir de 15 de novembro, e as subparcelas foram compostas por três cultivares: BMX Turbo RR (ciclo extra-precoce), BMX Potência RR (ciclo precoce) e TMG 1180 RR (ciclo médio). A semeadura tardia aumentou o índice de plastocrono e reduziu a duração do ciclo de crescimento, altura da planta, número de nós no caule principal e número de vagens por planta. Nossos resultados demonstram que cultivares com ciclos mais longos são mais adequadas para semeadura tardia, apresentam melhor desenvolvimento vegetativo e reprodutivo e maior rendimento de grãos. A segunda época de semeadura foi a mais adequada para o cultivo da soja na região.
ABSTRACT The sowing date is a crop management practice that affects soybean development and grain yield, and is directly related to the genotype and cycle type. Our objective was to evaluate phenological development as a function of photoperiodic responses, plastrochron index, and grain yield in three soybean cultivars with different growth cycles sown on three sowing dates. The study was conducted in Selvíria, Mato Grosso do Sul State, Brazil, using a split-plot design with the main plots arranged in blocks with four replications. The main plots included three sowing dates, 15 days apart, beginning on November 15, and the subplots were composed of three cultivars: BMX Turbo RR (extra-early cycle), BMX Potência RR (early cycle), and TMG 1180 RR (medium cycle). Delayed sowing increased the plastochron index and reduced the growth cycle duration, plant height, node number of the main stem, and pod number per plant. We found that cultivars with longer cycles were more suitable for delayed sowing, had improved vegetative and reproductive development, and had higher grain yields than those with shorter periods. The second sowing date was most suitable for soybean cultivation in this region.
2.
Felicidad y variables socioeconómicas en Arequipa (Perú)
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Villanueva Kuong, Leslie E.
; Arias Gallegos, Walter L.
; Ugarte Concha, Angel R.
; Esquivel Delgado, Augusto
; Barreda Parra, Ayme
.
Abstract: In this study we analyze the impact of several socioeconomic variables on the happiness of the inhabitants of Arequipa city, located at the south of Peru. In order to, there were applied a socioeconomic chart and the Lima Happiness Scale in a representative sample of823 people from Metropolitan Arequipa, obtained by the clustering technique. A multiple linear regression was applied to process the data, and the race was the unique variable significant statistically associated with the happiness of the inhabitants.
Resumen: En este estudio se analiza el impacto de diversas variables socioeconómicas en la felicidad de los habitantes de la ciudad de Arequipa, ubicada al sur de Perú. Para ello se aplicaron una ficha de datos sociodemográficos y la Escala de Felicidad de Lima a una muestra representativa de 823 personas de Arequipa Metropolitana, obtenida mediante la técnica de muestreo por racimos. Se aplicó un análisis de regresión lineal múltiple y se encontró que solo la variable raza se encuentra asociada de forma estadísticamente significativa con la felicidad de los habitantes.
3.
Guía de práctica clínica de la Sociedad Interamericana de Cardiología sobre prevención primaria de enfermedad cardiovascular en la mujer
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Sueldo, Mildren A. del
; Rivera, María A. Mendonça
; Sánchez-Zambrano, Martha B.
; Zilberman, Judith
; Múnera-Echeverri, Ana G.
; Paniagua, María
; Campos-Alcántara, Lourdes
; Almonte, Claudia
; Paix-Gonzales, Amalia
; Anchique-Santos, Claudia V.
; Coronel, Claudine J.
; Castillo, Gabriela
; Parra-Machuca, María G.
; Duro, Ivanna
; Varletta, Paola
; Delgado, Patricia
; Volberg, Verónica I.
; Puente-Barragán, Adriana C.
; Rodríguez, Adriana
; Rotta-Rotta, Aida
; Fernández, Anabela
; Izeta-Gutiérrez, Ana C.
; Ancona-Vadillo, Ana E.
; Aquieri, Analía
; Corrales, Andrea
; Simeone, Andrea
; Rubilar, Bibiana
; Artucio, Carolina
; Pimentel-Fernández, Carolina
; Marques-Santos, Celi
; Saldarriaga, Clara
; Chávez, Christian
; Cáceres, Cristina
; Ibarrola, Dahiana
; Barranco, Daniela
; Muñoz-Ortiz, Edison
; Ruiz-Gastelum, Edith D.
; Bianco, Eduardo
; Murguía, Elena
; Soto, Enrique
; Rodríguez-Caballero, Fabiola
; Otiniano-Costa, Fanny
; Valentino, Giovanna
; Rodríguez-Cermeño, Iris B.
; Rivera, Ivan R.
; Gándara-Ricardo, Jairo A.
; Velásquez-Penagos, Jesús A.
; Torales, Judith
; Scavenius, Karina
; Dueñas-Criado, Karen
; García, Laura
; Roballo, Laura
; Kazelian, Lucía R.
; Coussirat-Liendo, Macarena
; Costa-Almeida, María C.
; Drever, Mariana
; Lujambio, Mariela
; Castro, Marildes L.
; Rodríguez-Sifuentes, Maritza
; Acevedo, Mónica
; Giambruno, Mónica
; Ramírez, Mónica
; Gómez, Nancy
; Gutiérrez-Castillo, Narcisa
; Greatty, Onelia
; Harwicz, Paola
; Notaro, Patricia
; Falcón, Rocío
; López, Rosario
; Montefilpo, Sady
; Ramírez-Flores, Sara
; Verdugo, Silvina
; Murguía, Soledad
; Constantini, Sonia
; Vieira, Thais C.
; Michelis, Virginia
; Serra, César M.
.
https://doi.org/10.24875/acm.22000071
450 downloads
4.
Dynamic stability of a parallel kinematic machine
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Abstract: Machine tool chatter causes machining instability, surface roughness, and tool wear in metal cutting processes. According to the different chatter mechanisms, chatter can be categorized into regenerative chatter, mode coupling chatter, frictional chatter, and force-thermal chatter. Both mode coupling chatter and regenerative chatter may occur during the machining process, depending on the specific machinery and machining condition. The regenerative chatter happens locally at workpieces or cutting tools. The mode coupling chatter happens globally, including the entire configuration. This article extends chatter stability analysis to a decoupled parallel kinematic machine (PKM). The vibration model of the PKM focuses on the regenerative chatter while the decoupled design of the machine is proposed to eliminate any occurrence of mode coupling chatter. Thus, the features that make it suitable for machining tasks are highlighted. A stability lobe diagram based on the theory of regenerative vibration is an effective tool to predict chatter. The vibration model of the PKM is derived in which the dynamic behaviour of the spindle/holder/tool system is considered. Then, the regenerative cutting dynamics is combined with the vibration model and stability analysis is performed. A step-by-step procedure provides a stability lobe diagram. The chatter stability charts for various machining parameters are examined, with the example of the decoupled PKM that is specially designed for machine tool use.
5.
Crambe cake protein as a replacement for soybean meal protein: Intake, digestibility, and ruminal parameters in lamb diets
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Poveda-Parra, A.R.
; Pereira, E. S.
; Prado-Calixto, O. P.
; Guerra, G. L.
; Pires, K. A.
; Lopes, M. R.
; Rodrigues, E. R.
; Cavalheiro Junior, E. R.
; do Carmo, J. P. M.
; Mizubuti, I. Y.
.
The objective was to evaluate different levels of crambe cake protein (0, 250, 500, 750 and 1000 g/kg of DM) to replace soybean meal protein on the intake, apparent digestibility coefficient (ADC), blood glucose, ruminal fermentation, and protozoal population in lambs. Two experiments were performed. In experiment one, 40 crossbred male lambs weighing 20 ± 3.45 kg were used, distributed in a completely randomized design, to study intake and ruminal parameters. In experiment two, 25 crossbred male lambs weighing 23.44 ± 1.04 kg were used to study digestibility. The intake of dry matter and total carbohydrate (TC) (kg/lambs/day and g/kg0.75), crude protein (kg/lambs/day) and final body weight decreased with increase of crambe cake protein as a replacement for soybean meal protein, while ether extract ( EE) intake (kg/lambs/day and g/kg075) increased. The ADC of EE presented a positive linear effect and the ADC of TC and non-fibrous carbohydrates presented a negative linear effect. There was no interaction within treatments and collection period (0, 3, 6 and 9 h) on ruminal fluid characteristics. Blood glucose presented a quadratic effect for levels of crambe cake protein in diets (max. P = 35.18%), and linear increase for collection period. Ruminal pH showed a quadratic effect for sampling hours (max. P = 5.43 h). For protozoa evaluation, the total amount, Entodinium, and Eudiplodium presented linear decreasing effects with treatment, while Isotricha, Eudiplodium, Ostracodinium and the total amount of protozoa had a linear decrease with sampling hours. Soybean meal protein can be replaced by crambe cake protein at up to 250 g/kg DM.
6.
Pre-existing comorbidity, the highest risk factor for poor prognosis of COVID-19 among the Mexican population
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Calixto-Calderón, Basilio
; Vázquez-González, María F.
; Martínez-Peláez, Rafael
; Bermeo-Escalona, Josué R.
; García, Vicente
; Mena, Luis J.
; Maestre, Gladys
; Parra-Michel, Jorge R.
; Ceja Bravo, Leobardo A.
; López-de-Alba, Pedro L.
.
Abstract The coronavirus disease 2019 (COVID-19) pandemic represents a challenge for public health and a high risk for patients with pre-existing comorbidity. As of July 20, 2020, the Case Fatality Rate (CFR) was 11.30% and the Mortality Rate (MR) was 31.28 deaths per 100,000 population. In Mexico, the prevalence of obesity, diabetes mellitus, and hypertension among the adult Mexican population is 30%, 9.2%, and 40%, respectively. The objective of this research was to identify the risk factors associated with eight comorbidities and their dependency on age for death caused by COVID-19. Method: This study used the dataset published on July 20, 2020, by the General Directorate of Epidemiology of the Ministry of Health of Mexico. From this dataset, we analysed 130,896 positive COVID-19 cases, where 35,483 (27.107%) patients had one comorbidity, and 95,413 (72.892%) patients had not medical comorbidity. Statistical analyses include the Case Fatality Rate (CFR), the estimation of the Odds Ratio (OR), and its 95% Confidence Interval (CI). Results: The highest CFR was 14.382% for COPD, 10.266% for CKD, 10.126% for diabetes, and 8.954% for hypertension. The obesity CFR was 3.535%. Moreover, we detected a higher risk for patients with COPD, diabetes, and CKD, resulting in OR of 4.443 (95% CI: 3.404-5.799), 3.283 (95% CI: 3.018-3.570), and 3.016 (95% CI: 2.248-4.047), respectively. Conclusion: This study corroborates that the highest risk for severe disease and death caused by COVID-19 among the Mexican population are pre-existing comorbidities. Findings show that COPD, CKD, diabetes, hypertension, and cardiovascular disease increase the risk of death for patients older than 54 years. The most vulnerable age group is older than 65 years.
Resumen La pandemia de la enfermedad por coronavirus 2019 (COVID-19) representa un desafío para la salud pública y un alto riesgo para los pacientes con comorbilidad preexistente. Al 20 de julio de 2020, la Tasa de Casos Fatales fue de 11.30% y la Tasa de Mortalidad fue de 31.28 muertes por 100,000 habitantes. En México, la prevalencia de obesidad, diabetes mellitus e hipertensión entre la población adulta mexicana es de 30%, 9.2% y 40%, respectivamente. El objetivo de esta investigación fue identificar los factores de riesgo asociados a ocho comorbilidades y su dependencia de la edad para la muerte por COVID-19. Método: Este estudio utilizó el conjunto de datos publicado el 20 de julio de 2020 por la Dirección General de Epidemiología de la Secretaría de Salud de México. A partir de este conjunto de datos, se analizaron 130.896 casos positivos de COVID-19, donde 35.483 (27,107%) pacientes tenían una comorbilidad y 95.413 (72,892%) pacientes no tenían comorbilidad médica. Los análisis estadísticos incluyen la tasa de letalidad, la estimación de la razón de probabilidades y su intervalo de confianza del 95%. Resultados: La Tasa de Casos Fatales más altas fue 14.382% para EPOC (Enfermedad Pulmonar Obstructiva Crónica), 10.266% para ERC (Enfermedad Renal Crónica), 10.126% para diabetes y 8.954% para hipertensión. La tasa de riesgo para obesidad fue del 3,535%. Además, se detectó un mayor riesgo para los pacientes con EPOC, diabetes y ERC, lo que resultó en una OR de 4,443 (IC del 95%: 3,404-5,799), 3,283 (IC del 95%: 3,018-3,570) y 3,016 (IC del 95%: 2.248-4.047), respectivamente. Conclusión: Este estudio corrobora que el mayor riesgo de enfermedad grave y muerte causada por COVID-19 entre la población mexicana son las comorbilidades preexistentes. Los resultados muestran que EPOC, ERC, diabetes, hipertensión y enfermedades cardiovasculares aumentan el riesgo de muerte para pacientes mayores a 54 años. El grupo de edad más vulnerable es el de mayor a 65 años.
https://doi.org/10.21640/ns.v13ie.2823
613 downloads
7.
Elasticidad de la demanda en el subsistema de transporte masivo del Área Metropolitana Centro Occidente en función del incremento de la tarifa
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Resumen: En este trabajo, se presenta una estimación de la elasticidad de la demanda en un sistema de transporte público masivo, con respecto a su tarifa. Para realizar este cálculo, primero se establecieron unos intervalos de confianza para los períodos observados, luego, con estos valores aplicados a fórmulas de la literatura especializada, se obtuvo el valor de la elasticidad de la demanda con respecto al cambio de la tarifa de viaje. Esta estimación permite determinar el impacto del cambio tarifario en un sistema de transporte público de pasajeros específico, o si existen otros factores que tengan el mismo efecto en el sistema. En el caso de este estudio, se encuentra que el sistema es inelástico para 3 períodos de 6 observados, teniendo en los últimos 3 períodos, una estimación alta cuando se analizan otras razones que hayan influido en la demanda del sistema.
Abstract: In this work is presented the demand elasticity of a passenger’s public transport system with respect to bus fares. First, we established confidence intervals with the information of passengers who has used the transport system by periods. Once it has been defined the confidence intervals then the demand elasticity with respect to bus fare its calculated. This estimation allows to conclude how much the bus fare impacts the demand of the service, or if it exists another reason why the demand of the services has fluctuated during the history of the system. In this research it can be observed that the three first periods were inelastic and the next three periods were elastic, in the last periods its necessary to do a holistic view to find which another factor it’s the one who is affecting the passenger’s demand.
https://doi.org/10.31908/19098367.0008
269 downloads
8.
INFLUENCIA DEL FRÍO INVERNAL Y PORTAINJERTOS EN LA BROTACIÓN Y FLORACIÓN DEL MANZANO ROYAL GALA
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Peña-Antillón, Izdiana M.
; Jacobo-Cuéllar, Juan L.
; Parra-Quezada, Rafael A.
; Guerrero-Prieto, Víctor M.
; Ramírez-Legarreta, Manuel R.
; Ojeda-Barrios, Dámaris L.
; Hernández-Rodríguez, Ofelia A.
; Salas-Salazar, Nora A.
.
Abstract The apple tree (Malus sylvestris var. domestica) is grown in a wide variety of environments, with different rootstocks and cultivars; thus, the characterization of the response of the plant in each of the environmentcultivar-rootstock combinations is important to understand the tree behavior in its environment. In order to explore the influence ofwinter cold expressed in chill units (CU) accumulated during the winter period as well as rootstocks on bud breaking and blooming of apple trees, an apple orchard with the Royal Gala cultivar grafted on 12 different rootstocks was selected. During the winter periods of 2010-2011 and 2014-2015 CU were calculated and after that, the percentage of open buds and the day degrees (DD) required for the beggining (5 %) and during the flowering event (from 5 to 95 % ) for each of the environment-cultivar-rootstock combination were registered. The bud opening and blooming of Royal Gala were periodically measured in percentage of occurrence and related to CU, DD and rootstock. After a winter with low chill units accumulated (524 CU) there was 72.6 % of bud breaking, blooming began at 236 DD and was completed with 117 GDD, while after a winter with 830 CU there was 96.7 % of bud breaking, blooming began at 146 DD and was completed with 129 DD. Significant difference for winter cold factor was detected on bud breaking and DD accumulated at the beginning of blooming and statistical equality for the duration of blooming period. No significant effect of rootstocks or significant interaction between CU and rootstocks were detected.
Resumen El manzano (Malus sylvestris var. domestica) se cultiva en gran diversidad de ambientes, con diferentes portainjertos y cultivares, por lo que la caracterización de la respuesta de la planta en cada una de las combinaciones ambiente-cultivar-portainjerto es importante para entender el comportamiento del árbol en su entorno. Con el objetivo de explorar la influencia del frío invernal expresado en unidades frío (UF) acumuladas durante ese periodo y de portainjertos sobre la apertura de yemas y floración del manzano, se seleccionó un huerto con la variedad Royal Gala injertada sobre 12 portainjertos diferentes. En los inviernos 2010-2011 y 2014-2015 se calcularon las unidades frío y posterior a ésto, el porcentaje de yemas abiertas y los grados día (GD) requeridos para el inicio (5 %) y durante el evento de floración (de 5 a 95 %) para cada una de las combinaciones cultivar/ portainjerto. La apertura de yemas y el evento de floración de Royal Gala se midieron periódicamente en porcentaje relativo de ocurrencia y se relacionó con UF y portainjerto. Posterior a un invierno con baja acumulación de frío (524 UF) abrió el 72.6 % de yemas, la floración inició a los 236 GD y se completó en 117 GD, mientras que posterior a un invierno con 830 UF abrió el 96.7 % de yemas, la floración inició a los 146 GD y se completó en 129 GD. Se detectó influencia significativa del factor frío invernal para la apertura de yemas y para los GD acumulados al inicio de la floración e igualdad estadística para la duración de la floración. No se detectó efecto significativo de portainjerto ni interacción significativa entre frío invernal y portainjerto.
253 downloads
9.
Métodos de medición de espesores de películas delgadas basadas en óxidos semiconductores
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Abstract Transparent films based on Ti, Sn and Zn oxides are of great importance in electronic devices such as sensors, solar cells and conductive films, then the characterization techniques are highly relevant. The aim of this work is to identify the advantages and disadvantages of direct methods, such as profilometry, and indirect methods such as ellipsometry and spectrophotometry used to quantify film thickness. In this work, films were deposited by spray-pyrolysis on glass substrates at 425°C. Thicknesses varied between 150 and 300 nm. Thicknesses calculated by means of spectrophotometry and ellipsometry, led to differences below 10% and 20%, respectively, with respect to the value measured by profilometry.
Resumen Las películas transparentes basadas en óxidos de Ti, Sn y Zn tienen gran importancia en dispositivos electrónicos tales como sensores, celdas solares y películas conductoras haciendo que las técnicas de caracterización sean altamente relevantes. Este trabajo tiene como objetivo identificar las ventajas y desventajas de los métodos directos, tales como perfilometría e indirectos, elipsometría y espectrofotometría, para cuantificar espesores de películas delgadas de óxidos de Ti, Sn y Zn. Las películas se depositaron por spray-pyrolysis sobre sustratos de vidrio a 425°C. En todos los casos, los espesores obtenidos variaron entre 150 y 300 nm, con una diferencia inferior al 10% y 20% entre las técnicas espectrofotometría y elipsometría, respectivamente, con respecto al valor obtenido mediante perfilometría.
3899 downloads
10.
Assessment of some nongenetic factors that affect egg mass weight of channel catfish, Ictalurus punctatus
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Parra-Bracamonte, Gaspar M.
; Lara-Rivera, Ana L.
; Sifuentes-Rincón, Ana M.
; Martínez-González, Juan C.
; Rosa-Reyna, Xochitl F. De la
; Montelongo-Alfaro, Isidro
; Moreno-Medina, Victor R.
.
Abstract Channel catfish, Ictalurus punctatus, is one of the most important fish species for aquaculture worldwide. Egg mass production is directly related to the success and profitability of hatchery farms assuring an adequate egg and consequently fry and fingerling quantity. Most of the success of hatchery farms in Mexico rely on the capacity of production for enough fry to cover the demand of grow-out farms. An analysis was performed with the purpose of estimate the effect of year, month, color, pond and water temperature on egg mass weight data (EMW, g) (n = 3201). The overall mean for EMW was 683.21 g. The effect of all assessed factors was highly significant (P < 0.0001). Pond and year effects suggested an effect possibly related to management strategies. Month indicated an important effect on early spawning, and water temperature showed a highly significant effect of gradient pattern on EMW (P < 0.0001), with a linear slope of −67.8 g by increasing temperature degree. Results confirmed the importance of non-genetic influence on egg mass production, supporting the need for attention of this highly variable trait and suggested the possible improvement on this reproductive indicator through the better control of environmental sources of variation.
https://doi.org/10.3856/vol45-issue5-fulltext-13
374 downloads
11.
Proyección explícita e implícita del rendimiento maderable de plantaciones forestales comerciales de Pinus patula Schiede ex Schltdl. et Cham.
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Parra-Piedra, José P.
; Santos-Posadas, Héctor M. De los
; Fierros-González, Aurelio M.
; Valdez-Lazalde, José R.
; Romo-Lozano, José L.
.
Abstract In Zacualpan, Veracruz, Mexico, there are 3500 ha of commercial forest plantations of Pinus patula, but until now no evaluations of growth have been made that would allow an adequate programming of harvest. The objective of the present study was to evaluate growth and yield of timber, using an explicit and an implicit system with diametric distribution, both constructed with data of permanent forestry measurement plots. The hypothesis proposes that permanent observation plots, of different ages re-measured over time, will make it possible to obtain an explicit and implicit projected system of timber growth and yield. The first system is comprised of the polymorphic Schumacher-Korf type non-linear model in dominant height, of compatible equations of prediction-projection for basal area, total volume and mortality. The explicit system utilizes the Weibull probability distribution function of three parameters. For this study 50 sites of 400 m2 were randomly selected, distributed in age classes of three to 21 years, which were established in 2011 and were re-measured in 2012 and 2015. Results showed four site indices (SI): 10, 15, 20 and 25 m at the base age of 15 years. The technical rotation in volume for the average condition (SI of 20 m) was at 14 years, age at which 251 m3 ha-1 are produced as expected total volume and a mean yield of 17.9 m3 ha-1 year-1. The diametric distribution projected a total volume of 242 m3 ha-1 at the age of technical rotation, and also made it possible to know that the proportion of trees with normal diameter -30 cm is presented prior to 10 years in rich sites and afterwards is incremented exponentially.
Resumen En Zacualpan, Veracruz, México, existen 3,500 ha de plantaciones forestales comerciales de Pinus patula, pero hasta el momento no se han realizado evaluaciones de crecimiento que permitan programar adecuadamente la cosecha. El objetivo del estudio fue evaluar el crecimiento y rendimiento maderable, compuesto por un sistema explícito y uno implícito con distribución diamétrica, ambos construidos con datos de parcelas permanentes de medición forestal. La hipótesis propone que parcelas de observación permanente, de diferentes edades entre ellas y remedidas en el tiempo, permitirán obtener un sistema de crecimiento y rendimiento maderable proyectado en forma explícita e implícita. El primer sistema consta del modelo no lineal en altura dominante tipo Schumacher-Korf polimórfico y de ecuaciones compatibles de predicción - proyección para área basal, volumen total y mortalidad. El sistema implícito utilizó la función de la distribución de probabilidad Weibull de tres parámetros. Para el estudio se eligieron al azar 50 sitios de 400 m2 cada uno, distribuidos en clases de edad de tres hasta 21 años, se establecieron en el 2011 y se remidieron en 2012 y 2015. Los resultados mostraron cuatro índices de sitio (IS): 10, 15, 20 y 25 m a la edad base de 15 años. El turno técnico en volumen para la condición promedio (IS de 20 m) fue de 14 años, edad a la que se producen 251 m3 ha-1 como volumen total esperado y un rendimiento medio de 17.9 m3 ha-1 año-1. La distribución diamétrica proyectó un volumen total de 242 m3 ha-1 a la edad del turno técnico y, además, permitió conocer que la proporción de árboles con diámetro normal -30 cm se presenta antes de los 10 años en sitios ricos y después se incrementa exponencialmente.
1494 downloads
12.
Interactions between Escherichia coli O157:H7 and food plants. Has this bacterium developed internalization mechanisms?
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Torres Armendáriz, V.
; Manjarrez Domínguez, C. B.
; Acosta-Muñiz, C. H.
; Guerrero-Prieto, V. M.
; Parra-Quezada, R. Á.
; Noriega Orozco, L. O.
; Ávila-Quezada, G. D.
.
Abstract: Despite efforts to prevent microbial contamination, the occurrence of human pathogens in fresh fruit and vegetable is quite common. It is now known that E. coli O157:H7 can inhabit food plants passively. Here, we review the literature on phylloplane adhesion, survival and internalization of this bacterium, as well as some of the interaction mechanisms between it and the food plant, and other associated microorganisms. This pathogen, once it has adhered to the surface of a food plant, can then enter the plant tissues, where it can migrate within them, and even multiply. This review provides an overview of the interaction mechanisms between the food plant tissues and E. coli O157:H7. It finds that this pathogen has improved its ecological competence in food plants without losing its virulence to humans. Also, a number of future research areas were identified.
Resumen: La presencia de bacterias patógenas en frutas y hortalizas es muy común a pesar de los grandes esfuerzos realizados para prevenir la contaminación microbiologica. En la actualidad, se sabe (o se conoce) que E. coli O157:H7 puede colonizar de forma pasiva plantas comestibles. Este trabajo presenta una revisión de literatura sobre E. coli y su adhesión al filoplano, supervivencia e internalización, así como mecanismos de interacción bacteria-planta. Una vez, que este patógeno, se adhiere a la superficie de la planta, puede introducirse al tejido, para después movilizarse y multiplicarse. Esta revisión ofrece una visión general de los mecanismos de interacción entre el tejido vegetal y E. coli O157:H7. Se considera que este patógeno ha mejorado su competencia ecológica en plantas comestibles, sin perder su virulencia para el ser humano. Además, se identificaron áreas de oportunidad para futuros trabajos de investigación.
https://doi.org/10.18781/R.MEX.FIT.1507-4
4426 downloads
13.
Unusual remodeling of the hyalinization band in vulval lichen sclerosus by type V collagen and ECM 1 protein
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Godoy, Charles A.P.
; Teodoro, Walcy R.
; Velosa, Ana Paula P.
; Garippo, Ana Lucia
; Eher, Esmeralda Miristeni
; Parra, Edwin Roger
; Sotto, Mirian N.
; Capelozzi, Vera L.
.
OBJECTIVES: The vulva is the primary site affected in lichen sclerosus, a chronic dermatosis in women that is histologically characterized by a zone of collagen remodeling in the superior dermis. The normal physiological properties of the vulva depend on the assembly of collagen types I (COLI), III (COLIII) and V (COLV), which form heterotypic fibers, and extracellular matrix protein interactions. COLV regulates the heterotypic fiber diameter, and the preservation of its properties is important for maintaining normal tissue architecture and function. In the current work, we analyzed the expression of COLV and its relationship with COLI, COLIII, elastic fibers and extracellular matrix protein 1 in vulvar biopsies from patients with lichen sclerosus. METHODS: Skin biopsies from 21 patients with lichen sclerosus, classified according to Hewitt histological criteria, were studied and compared to clinically normal vulvar tissue (N=21). Morphology, immunohistochemistry, immunofluorescence, 3D reconstruction and morphometric analysis of COLI, COLIII, COLV deposition, elastic fibers and extracellular matrix 1 expression in a zone of collagen remodeling in the superior dermis were performed. RESULTS: A significant decrease of elastic fibers and extracellular matrix 1 protein was present in the hyalinization zone of lichen sclerosus compared to healthy controls. The non-homogeneous distribution of collagen fibers visualized under immunofluorescence in the hyalinization zone of lichen sclerosus and control skin was confirmed by histomorphometry. Lichen sclerosus dermis shows a significant increase of COLI, COLIII and COLV expression compared to the healthy controls. Significant inverse associations were found between elastic fibers and COLV and between COLV and extracellular matrix 1 expression. A direct association was found between elastic fiber content and extracellular matrix 1 expression. Tridimensional reconstruction of the heterotypic fibers of the lichen sclerosus zone of collagen remodeling confirmed the presence of densely clustered COLV. CONCLUSIONS: Increased deposition of abnormal COLV and its correlation with extracellular matrix 1 and elastic fibers suggest that COLV may be a trigger in the pathogenesis of lichen sclerosus.
https://doi.org/10.6061/clinics/2015(05)09
2726 downloads
14.
Growing knowledge: an overview of Seed Plant diversity in Brazil
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Zappi, Daniela C.
; Filardi, Fabiana L. Ranzato
; Leitman, Paula
; Souza, Vinícius C.
; Walter, Bruno M.T.
; Pirani, José R.
; Morim, Marli P.
; Queiroz, Luciano P.
; Cavalcanti, Taciana B.
; Mansano, Vidal F.
; Forzza, Rafaela C.
; Abreu, Maria C.
; Acevedo-Rodríguez, Pedro
; Agra, Maria F.
; Almeida Jr., Eduardo B.
; Almeida, Gracineide S.S.
; Almeida, Rafael F.
; Alves, Flávio M.
; Alves, Marccus
; Alves-Araujo, Anderson
; Amaral, Maria C.E.
; Amorim, André M.
; Amorim, Bruno
; Andrade, Ivanilza M.
; Andreata, Regina H.P.
; Andrino, Caroline O.
; Anunciação, Elisete A.
; Aona, Lidyanne Y.S.
; Aranguren, Yani
; Aranha Filho, João L.M.
; Araújo, Andrea O.
; Araújo, Ariclenes A.M.
; Araújo, Diogo
; Arbo, María M.
; Assis, Leandro
; Assis, Marta C.
; Assunção, Vivian A.
; Athiê-Souza, Sarah M.
; Azevedo, Cecilia O.
; Baitello, João B.
; Barberena, Felipe F.V.A.
; Barbosa, Maria R.V.
; Barros, Fábio
; Barros, Lucas A.V.
; Barros, Michel J.F.
; Baumgratz, José F.A.
; Bernacci, Luis C.
; Berry, Paul E.
; Bigio, Narcísio C.
; Biral, Leonardo
; Bittrich, Volker
; Borges, Rafael A.X.
; Bortoluzzi, Roseli L.C.
; Bove, Cláudia P.
; Bovini, Massimo G.
; Braga, João M.A.
; Braz, Denise M.
; Bringel Jr., João B.A.
; Bruniera, Carla P.
; Buturi, Camila V.
; Cabral, Elza
; Cabral, Fernanda N.
; Caddah, Mayara K.
; Caires, Claudenir S.
; Calazans, Luana S.B.
; Calió, Maria F.
; Camargo, Rodrigo A.
; Campbell, Lisa
; Canto-Dorow, Thais S.
; Carauta, Jorge P.P.
; Cardiel, José M.
; Cardoso, Domingos B.O.S.
; Cardoso, Leandro J.T.
; Carneiro, Camila R.
; Carneiro, Cláudia E.
; Carneiro-Torres, Daniela S.
; Carrijo, Tatiana T.
; Caruzo, Maria B.R.
; Carvalho, Maria L.S.
; Carvalho-Silva, Micheline
; Castello, Ana C.D.
; Cavalheiro, Larissa
; Cervi, Armando C.
; Chacon, Roberta G.
; Chautems, Alain
; Chiavegatto, Berenice
; Chukr, Nádia S.
; Coelho, Alexa A.O.P.
; Coelho, Marcus A.N.
; Coelho, Rubens L.G.
; Cordeiro, Inês
; Cordula, Elizabeth
; Cornejo, Xavier
; Côrtes, Ana L.A.
; Costa, Andrea F.
; Costa, Fabiane N.
; Costa, Jorge A.S.
; Costa, Leila C.
; Costa-e-Silva, Maria B.
; Costa-Lima, James L.
; Cota, Maria R.C.
; Couto, Ricardo S.
; Daly, Douglas C.
; De Stefano, Rodrigo D.
; De Toni, Karen
; Dematteis, Massimiliano
; Dettke, Greta A.
; Di Maio, Fernando R.
; Dórea, Marcos C.
; Duarte, Marília C.
; Dutilh, Julie H.A.
; Dutra, Valquíria F.
; Echternacht, Lívia
; Eggers, Lilian
; Esteves, Gerleni
; Ezcurra, Cecilia
; Falcão Junior, Marcus J.A.
; Feres, Fabíola
; Fernandes, José M.
; Ferreira, D.M.C.
; Ferreira, Fabrício M.
; Ferreira, Gabriel E.
; Ferreira, Priscila P.A.
; Ferreira, Silvana C.
; Ferrucci, Maria S.
; Fiaschi, Pedro
; Filgueiras, Tarciso S.
; Firens, Marcela
; Flores, Andreia S.
; Forero, Enrique
; Forster, Wellington
; Fortuna-Perez, Ana P.
; Fortunato, Reneé H.
; Fraga, Cléudio N.
; França, Flávio
; Francener, Augusto
; Freitas, Joelcio
; Freitas, Maria F.
; Fritsch, Peter W.
; Furtado, Samyra G.
; Gaglioti, André L.
; Garcia, Flávia C.P.
; Germano Filho, Pedro
; Giacomin, Leandro
; Gil, André S.B.
; Giulietti, Ana M.
; A.P.Godoy, Silvana
; Goldenberg, Renato
; Gomes da Costa, Géssica A.
; Gomes, Mário
; Gomes-Klein, Vera L.
; Gonçalves, Eduardo Gomes
; Graham, Shirley
; Groppo, Milton
; Guedes, Juliana S.
; Guimarães, Leonardo R.S.
; Guimarães, Paulo J.F.
; Guimarães, Elsie F.
; Gutierrez, Raul
; Harley, Raymond
; Hassemer, Gustavo
; Hattori, Eric K.O.
; Hefler, Sonia M.
; Heiden, Gustavo
; Henderson, Andrew
; Hensold, Nancy
; Hiepko, Paul
; Holanda, Ana S.S.
; Iganci, João R.V.
; Imig, Daniela C.
; Indriunas, Alexandre
; Jacques, Eliane L.
; Jardim, Jomar G.
; Kamer, Hiltje M.
; Kameyama, Cíntia
; Kinoshita, Luiza S.
; Kirizawa, Mizué
; Klitgaard, Bente B.
; Koch, Ingrid
; Koschnitzke, Cristiana
; Krauss, Nathália P.
; Kriebel, Ricardo
; Kuntz, Juliana
; Larocca, João
; Leal, Eduardo S.
; Lewis, Gwilym P.
; Lima, Carla T.
; Lima, Haroldo C.
; Lima, Itamar B.
; Lima, Laíce F.G.
; Lima, Laura C.P.
; Lima, Leticia R.
; Lima, Luís F.P.
; Lima, Rita B.
; Lírio, Elton J.
; Liro, Renata M.
; Lleras, Eduardo
; Lobão, Adriana
; Loeuille, Benoit
; Lohmann, Lúcia G.
; Loiola, Maria I.B.
; Lombardi, Julio A.
; Longhi-Wagner, Hilda M.
; Lopes, Rosana C.
; Lorencini, Tiago S.
; Louzada, Rafael B.
; Lovo, Juliana
; Lozano, Eduardo D.
; Lucas, Eve
; Ludtke, Raquel
; Luz, Christian L.
; Maas, Paul
; Machado, Anderson F.P.
; Macias, Leila
; Maciel, Jefferson R.
; Magenta, Mara A.G.
; Mamede, Maria C.H.
; Manoel, Evelin A.
; Marchioretto, Maria S.
; Marques, Juliana S.
; Marquete, Nilda
; Marquete, Ronaldo
; Martinelli, Gustavo
; Martins da Silva, Regina C.V.
; Martins, Ângela B.
; Martins, Erika R.
; Martins, Márcio L.L.
; Martins, Milena V.
; Martins, Renata C.
; Matias, Ligia Q.
; Maya-L., Carlos A.
; Mayo, Simon
; Mazine, Fiorella
; Medeiros, Debora
; Medeiros, Erika S.
; Medeiros, Herison
; Medeiros, João D.
; Meireles, José E.
; Mello-Silva, Renato
; Melo, Aline
; Melo, André L.
; Melo, Efigênia
; Melo, José I.M.
; Menezes, Cristine G.
; Menini Neto, Luiz
; Mentz, Lilian A.
; Mezzonato, A.C.
; Michelangeli, Fabián A.
; Milward-de-Azevedo, Michaele A.
; Miotto, Silvia T.S.
; Miranda, Vitor F.O.
; Mondin, Cláudio A.
; Monge, Marcelo
; Monteiro, Daniele
; Monteiro, Raquel F.
; Moraes, Marta D.
; Moraes, Pedro L.R.
; Mori, Scott A.
; Mota, Aline C.
; Mota, Nara F.O.
; Moura, Tania M.
; Mulgura, Maria
; Nakajima, Jimi N.
; Nardy, Camila
; Nascimento Júnior, José E.
; Noblick, Larry
; Nunes, Teonildes S.
; O'Leary, Nataly
; Oliveira, Arline S.
; Oliveira, Caetano T.
; Oliveira, Juliana A.
; Oliveira, Luciana S.D.
; Oliveira, Maria L.A.A.
; Oliveira, Regina C.
; Oliveira, Renata S.
; Oliveira, Reyjane P.
; Paixão-Souza, Bruno
; Parra, Lara R.
; Pasini, Eduardo
; Pastore, José F.B.
; Pastore, Mayara
; Paula-Souza, Juliana
; Pederneiras, Leandro C.
; Peixoto, Ariane L.
; Pelissari, Gisela
; Pellegrini, Marco O.O.
; Pennington, Toby
; Perdiz, Ricardo O.
; Pereira, Anna C.M.
; Pereira, Maria S.
; Pereira, Rodrigo A.S.
; Pessoa, Clenia
; Pessoa, Edlley M.
; Pessoa, Maria C.R.
; Pinto, Luiz J.S.
; Pinto, Rafael B.
; Pontes, Tiago A.
; Prance, Ghillean T.
; Proença, Carolyn
; Profice, Sheila R.
; Pscheidt, Allan C.
; Queiroz, George A.
; Queiroz, Rubens T.
; Quinet, Alexandre
; Rainer, Heimo
; Ramos, Eliana
; Rando, Juliana G.
; Rapini, Alessandro
; Reginato, Marcelo
; Reis, Ilka P.
; Reis, Priscila A.
; Ribeiro, André R.O.
; Ribeiro, José E.L.S.
; Riina, Ricarda
; Ritter, Mara R.
; Rivadavia, Fernando
; Rocha, Antônio E.S.
; Rocha, Maria J.R.
; Rodrigues, Izabella M.C.
; Rodrigues, Karina F.
; Rodrigues, Rodrigo S.
; Rodrigues, Rodrigo S.
; Rodrigues, Vinícius T.
; Rodrigues, William
; Romaniuc Neto, Sérgio
; Romão, Gerson O.
; Romero, Rosana
; Roque, Nádia
; Rosa, Patrícia
; Rossi, Lúcia
; Sá, Cyl F.C.
; Saavedra, Mariana M.
; Saka, Mariana
; Sakuragui, Cássia M.
; Salas, Roberto M.
; Sales, Margareth F.
; Salimena, Fatima R.G.
; Sampaio, Daniela
; Sancho, Gisela
; Sano, Paulo T.
; Santos, Alessandra
; Santos, Élide P.
; Santos, Juliana S.
; Santos, Marianna R.
; Santos-Gonçalves, Ana P.
; Santos-Silva, Fernanda
; São-Mateus, Wallace
; Saraiva, Deisy P.
; Saridakis, Dennis P.
; Sartori, Ângela L.B.
; Scalon, Viviane R.
; Schneider, Ângelo
; Sebastiani, Renata
; Secco, Ricardo S.
; Senna, Luisa
; Senna-Valle, Luci
; Shirasuna, Regina T.
; Silva Filho, Pedro J.S.
; Silva, Anádria S.
; Silva, Christian
; Silva, Genilson A.R.
; Silva, Gisele O.
; Silva, Márcia C.R.
; Silva, Marcos J.
; Silva, Marcos J.
; Silva, Otávio L.M.
; Silva, Rafaela A.P.
; Silva, Saura R.
; Silva, Tania R.S.
; Silva-Gonçalves, Kelly C.
; Silva-Luz, Cíntia L.
; Simão-Bianchini, Rosângela
; Simões, André O.
; Simpson, Beryl
; Siniscalchi, Carolina M.
; Siqueira Filho, José A.
; Siqueira, Carlos E.
; Siqueira, Josafá C.
; Smith, Nathan P.
; Snak, Cristiane
; Soares Neto, Raimundo L.
; Soares, Kelen P.
; Soares, Marcos V.B.
; Soares, Maria L.
; Soares, Polyana N.
; Sobral, Marcos
; Sodré, Rodolfo C.
; Somner, Genise V.
; Sothers, Cynthia A.
; Sousa, Danilo J.L.
; Souza, Elnatan B.
; Souza, Élvia R.
; Souza, Marcelo
; Souza, Maria L.D.R.
; Souza-Buturi, Fátima O.
; Spina, Andréa P.
; Stapf, María N.S.
; Stefano, Marina V.
; Stehmann, João R.
; Steinmann, Victor
; Takeuchi, Cátia
; Taylor, Charlotte M.
; Taylor, Nigel P.
; Teles, Aristônio M.
; Temponi, Lívia G.
; Terra-Araujo, Mário H.
; Thode, Veronica
; Thomas, W.Wayt
; Tissot-Squalli, Mara L.
; Torke, Benjamin M.
; Torres, Roseli B.
; Tozzi, Ana M.G.A.
; Trad, Rafaela J.
; Trevisan, Rafael
; Trovó, Marcelo
; Valls, José F.M.
; Vaz, Angela M.S.F.
; Versieux, Leonardo
; Viana, Pedro L.
; Vianna Filho, Marcelo D.M.
; Vieira, Ana O.S.
; Vieira, Diego D.
; Vignoli-Silva, Márcia
; Vilar, Thaisa
; Vinhos, Franklin
; Wallnöfer, Bruno
; Wanderley, Maria G.L.
; Wasshausen, Dieter
; Watanabe, Maurício T.C.
; Weigend, Maximilian
; Welker, Cassiano A.D.
; Woodgyer, Elizabeth
; Xifreda, Cecilia C.
; Yamamoto, Kikyo
; Zanin, Ana
; Zenni, Rafael D.
; Zickel, Carmem S
.
Resumo Um levantamento atualizado das plantas com sementes e análises relevantes acerca desta biodiversidade são apresentados. Este trabalho se iniciou em 2010 com a publicação do Catálogo de Plantas e Fungos e, desde então vem sendo atualizado por mais de 430 especialistas trabalhando online. O Brasil abriga atualmente 32.086 espécies nativas de Angiospermas e 23 espécies nativas de Gimnospermas e estes novos dados mostram um aumento de 3% da riqueza em relação a 2010. A Amazônia é o Domínio Fitogeográfico com o maior número de espécies de Gimnospermas, enquanto que a Floresta Atlântica possui a maior riqueza de Angiospermas. Houve um crescimento considerável no número de espécies e nas taxas de endemismo para a maioria dos Domínios (Caatinga, Cerrado, Floresta Atlântica, Pampa e Pantanal), com exceção da Amazônia que apresentou uma diminuição de 2,5% de endemicidade. Entretanto, a maior parte das plantas com sementes que ocorrem no Brasil (57,4%) é endêmica deste território. A proporção de formas de vida varia de acordo com os diferentes Domínios: árvores são mais expressivas na Amazônia e Floresta Atlântica do que nos outros biomas, ervas são dominantes no Pampa e as lianas apresentam riqueza expressiva na Amazônia, Floresta Atlântica e Pantanal. Este trabalho não só quantifica a biodiversidade brasileira, mas também indica as lacunas de conhecimento e o desafio a ser enfrentado para a conservação desta flora.
Abstract An updated inventory of Brazilian seed plants is presented and offers important insights into the country's biodiversity. This work started in 2010, with the publication of the Plants and Fungi Catalogue, and has been updated since by more than 430 specialists working online. Brazil is home to 32,086 native Angiosperms and 23 native Gymnosperms, showing an increase of 3% in its species richness in relation to 2010. The Amazon Rainforest is the richest Brazilian biome for Gymnosperms, while the Atlantic Rainforest is the richest one for Angiosperms. There was a considerable increment in the number of species and endemism rates for biomes, except for the Amazon that showed a decrease of 2.5% of recorded endemics. However, well over half of Brazillian seed plant species (57.4%) is endemic to this territory. The proportion of life-forms varies among different biomes: trees are more expressive in the Amazon and Atlantic Rainforest biomes while herbs predominate in the Pampa, and lianas are more expressive in the Amazon, Atlantic Rainforest, and Pantanal. This compilation serves not only to quantify Brazilian biodiversity, but also to highlight areas where there information is lacking and to provide a framework for the challenge faced in conserving Brazil's unique and diverse flora.
https://doi.org/10.1590/2175-7860201566411
33340 downloads
15.
Biopolymer-clay nanocomposites: cassava starch and synthetic clay cast films
Facebook Twitter
Facebook Twitter
- Other social networks
- Google+
- StambleUpon
- CiteULike
- Mendeley
- Other networks
- Metrics
Perotti, Gustavo F.
; Tronto, Jairo
; Bizeto, Marcos A.
; Izumi, Celly M. S.
; Temperini, Marcia L. A.
; Lugão, Ademar B.
; Parra, Duclerc F.
; Constantino, Vera R. L.
.
Nanocompósitos à base de amido de mandioca, argila sintética hectorita e açúcar invertido (plastificante) foram preparados por processo em meio aquoso (casting) produzindo filmes transparentes e homogêneos. Pequenas quantidades de argila (5-15% em massa) produzem principalmente nanocompósitos esfoliados, enquanto grandes quantidades (30% em massa) promovem a formação de nanocompósitos intercalados. Os espectros FT-Raman mostram que bandas sensíveis à ligação de hidrogênio em grânulos de amido são progressivamente deslocadas para frequências menores quando o teor de argila é aumentado. Os nanocompósitos mostram um comportamento térmico semelhante até 320 ºC, enquanto a decomposição da biomolécula em cerca de 500 ºC é dependente do teor de argila. A liberação de CO2 em aproximadamente 300 ºC (decomposição não oxidativa das cadeias poliméricas) diminui se comparada com o desprendimento desse gás em 500 ºC quando a quantidade de argila é aumentada. Filmes com teor de argila maior que 10% não mostram melhora substancial nas propriedades de alongamento ou resistência.
Polymer-clay nanocomposites (PCN) based on cassava starch, synthetic hectorite clay and inverted sugar cane syrup (plasticizer) were prepared by solvent-assisted (casting) process producing transparent and homogeneous films. Small amounts of clay (5-15 wt.%) resulted mainly in exfoliated nanocomposites while large amounts (30 wt.%) promote the intercalated nanocomposites formation. FT-Raman bands sensitive to hydrogen bonding in starch granules are progressively shifted to lower wavenumbers as the clay content is raised. Nanocomposites show a similar thermal behavior up to 320 ºC while the biomolecule decomposition at about 500 ºC is dependent on the clay content. CO2 release at about 300 ºC (non-oxidative decomposition of polymeric chains) decreases if compared to the gas delivery at ca. 500 ºC, as the clay content is increased. Films with clay content higher than 10 wt.% show no substantial benefit for either elongation or resistance properties.
https://doi.org/10.5935/0103-5053.20130300
5023 downloads
Showing
itens per page
Page
of 3
Next
Statistics of
Send result
Sem resultados
No documents were found for your search
Glossary and search help
You can enrich your search in a very simple way. Use the search indexes combined with the connectors (AND or OR) and specify more your search.
For example, if you want to search for articles about
cases of dengue in Brasil in 2015, use:ti:dengue and publication_year:2015 and aff_country:Brasil
See below the complete list of search indexes that can be used:
Index code | Element |
---|---|
ti | article title |
au | author |
kw | article keywords |
subject | subject (title words, abstract and keywords) |
ab | abstract |
ta | journal short title (e.g. Cad. Saúde Pública) |
journal_title | journal full title (e.g. Cadernos de Saúde Pública) |
la | publication language code (e.g. pt - Portuguese, es - Spanish) |
type | document type |
pid | publication identifier |
publication_year | publication year of publication |
sponsor | sponsor |
aff_country | country code of the author's affiliation |
aff_institution | author affiliation institution |
volume | article volume |
issue | article issue |
elocation | elocation |
doi | DOI number |
issn | journal ISSN |
in | SciELO colection code (e.g. scl - Brasil, col - Colômbia) |
use_license | article usage license code |