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Effect of temperature on the electro-oxidation of ethanol on platinum

CAMARGO, Ana Paula M.; PREVIDELLO, Bruno A. F.; VARELA, Hamilton; GONZALEZ, Ernesto R.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
75.47%
We present in this work an experimental investigation of the effect of temperature (from 25 to 180 ºC) in the electro-oxidation of ethanol on platinum in two different phosphoric acid concentrations. We observed that the onset potential for ethanol electro-oxidation shifts to lower values and the reaction rates increase as temperature is increased for both electrolytes. The results were rationalized in terms of the effect of temperature on the adsorption of reaction intermediates, poisons, and anions. The formation of oxygenated species at high potentials, mainly in the more diluted electrolyte, also contributes to increase the electro-oxidation reaction rate.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Pesquisa (CNPq)

Avaliação de danos e efeito de variáveis ambientais na mancha de alternaria (Alternaria helianthi) em Girassol.; Damage assessment and effect of environmental variables on alternaria leaf spot (Alternaria helianthi) in sunflower.

Leite, Regina Maria Villas Bôas de Campos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 27/08/2002 PT
Relevância na Pesquisa
75.46%
O desenvolvimento e implementação de uma estratégia de manejo integrado de doenças na cultura do girassol (Helianthus annuus) requer informações precisas e acuradas sobre os danos causados pela mancha de Alternaria, causada por Alternaria helianthi. Os objetivos desta tese foram: elaborar e validar uma escala diagramática para avaliação da mancha de Alternaria; determinar a influência da temperatura (15-32,5 °C) e da duração do período de molhamento foliar (2-24 h) nos componentes monocíclicos da doença; comparar a relação de variáveis relacionadas à doença ou à área foliar com os componentes de produção de girassol, em experimentos de campo. A escala diagramática, com níveis de severidade de: 0,03; 0,2; 0,6; 3; 7; 12; 25; 40 e 66% da área foliar lesionada, foi validada por três avaliadores experientes. A escala permitiu que se fizesse uma avaliação acurada e precisa, quando se utilizou folhas desenhadas ou folhas verdes com sintomas. O erro absoluto ao estimar a severidade foi menor que 13% e a reprodutibilidade das avaliações foi alta. Em ambiente controlado, verificou-se que a densidade relativa de lesões e a severidade foram influenciadas pela temperatura e pela duração do período de molhamento foliar. A doença foi mais severa na temperatura de 25 °C. A temperatura mínima para desenvolvimento da doença foi de 13...

Effect of temperature on different stages of Romanomermis iyengari, a mermithid nematode parasite of mosquitoes

Paily,K. P.; Balaraman,K.
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/1994 EN
Relevância na Pesquisa
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The effect of temperature (20 degrees-35 degrees C) on different stages of Romanomermis iyengari was studied. In embryonic development, the single-cell stage eggs developed into mature eggs in 4.5-6.5 days at 25-35 degrees C but, required 9.5 days at 20 degrees C. Complete hatching occurred in 7 and 9 days after egg-laying at 35 and 30 degrees C, respectively. At 25 and 20 degrees C, 85-96 of the eggs did not hatch even by 30th day. Loss of infectivity and death of the preparasites occurred faster at higher temperatures. The 50 survival durations of preparasites at 20 and 35 degrees C were 105.8 and 10.6 hr respectively. They retained 50 infectivity up to 69.7 and 30.3 hr. The duration of the parasitic phase increased as temperature decreased. Low temperature favoured production of a higher proportion of females which were also larger in size. The maximum time taken for the juveniles to become adults was 14 days at 20 degrees C and the minimum was 9 days at 35 degrees C. Oviposition began earlier at higher temperature than at lower temperature. However, its fecundic period was shorter at 20 degrees C than at 35 degrees C indicating enhanced rate of oviposition at 20 degrees C. Fecundity was adversely affected at 20 degrees C and 35 degrees C. It is shown that the temperature range of 25 degrees-30 degrees C favours optimum development of R. iyengari.

Effect of temperature on the electro-oxidation of ethanol on platinum

Camargo,Ana Paula M.; Previdello,Bruno A. F.; Varela,Hamilton; Gonzalez,Ernesto R.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
Relevância na Pesquisa
75.47%
We present in this work an experimental investigation of the effect of temperature (from 25 to 180 ºC) in the electro-oxidation of ethanol on platinum in two different phosphoric acid concentrations. We observed that the onset potential for ethanol electro-oxidation shifts to lower values and the reaction rates increase as temperature is increased for both electrolytes. The results were rationalized in terms of the effect of temperature on the adsorption of reaction intermediates, poisons, and anions. The formation of oxygenated species at high potentials, mainly in the more diluted electrolyte, also contributes to increase the electro-oxidation reaction rate.

Effect of temperature on the mechanical properties of polymer mortars

Reis,João Marciano Laredo dos
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2012 EN
Relevância na Pesquisa
75.46%
This paper presents the results of an experimental program to investigate the effect of temperature on the performance of epoxy and unsaturated polyester polymer mortars (PM). PM is a composite material in which polymeric materials are used to bond the aggregates in a fashion similar to that used in the preparation of Portland cement concrete. For this purpose, prismatic and cylindrical specimens were prepared for flexural and compressive tests, respectively, at different temperatures. Measurements of the temperature-dependent elastic modulus and the compressive and flexural strength were conducted using a thermostatic chamber attached to a universal test machine for a range of temperatures varying from room temperature to 90 ºC. The flexural and compressive strength decreases as temperature increases, especially after matrix HDT. Epoxy polymer mortars are more sensitive to temperature variation than unsaturated polyester ones.

Effect of Temperature and Capsid Tail on the Packing and Ejection of Viral DNA

Al Lawati, Afaf; Ali, Issam; Al Barwani, Muataz
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 08/01/2013 EN
Relevância na Pesquisa
75.47%
We use a simulation technique based on molecular dynamics and stochastic rotation model to present the effect of temperature and capsid tail on the packaging and ejection processes of semiflexible polymers. We consider two types of solvents, a good solvent, where the polymer is neutral and repulsion interactions among its various sections are favored, and one where the polymer is charged, giving rise to extra electrostatic reaction. For tailless capsids, we find that packing a neutral polymer is slightly slower at higher temperatures whereas its ejection is slightly slower at lower temperatures. We find the same trend for a charged polymer but the effect is noticeably larger. At a high enough temperature, we notice that packing a charged polymer can be stopped. On the other hand, at fixed temperature and regardless whether the polymer is charged, packing is much easier for a capsid with a tail whereas ejection is much slower. The effect of including the tail on the dynamics of a charged polymer, in particular, is rather significant: more packing fraction is facilitated at higher temperatures due to more ordered polymer configuration inside the capsid. In contrast, during ejection the tail traps the last remaining beads for quite some time before allowing full ejection. We interpret these results in terms of entropic and electrostatic forces.

The effect of temperature on the bystander effect as examined in human prostate carcinoma cells with alpha particle irradiation

Sheppard, Sarah (Sarah Elizabeth)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 32 p.
ENG
Relevância na Pesquisa
85.47%
The bystander effect is seen when irradiated cells release a factor that can produce damage or death in neighboring "bystander" cells that are not actually hit by any radiation. One proposed mechanism involves the irradiated cells releasing a soluble factor into the medium that can cause damage to the non-irradiated cells. Previous studies in the Coderre lab showed that the soluble factor released by DU-145 human prostate carcinoma cells was a short-lived, free radical species (Wang and Coderre, Rad. Res., 164, 711-722, 2005). This thesis examined the effect of temperature on the bystander effect. A co-culture system was used to create irradiated and bystander DU-145 cells in the same medium. This thesis showed that a decrease in temperature lessens or prevents the bystander effect. Researching the bystander effect will allow a better understanding of a process that may already be occurring during alpha-particle based therapies such as boron neutron capture therapy (BNCT) and tumor radioimmunotherapy and could provide a means to improve these therapies.; by Sarah Sheppard.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2006.; "June 2006."; Includes bibliographical references (p. 30-32).

The effects of temperature on nickel tocicity in goldfish (carassius auratus L.)

Norris, Stacey L.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
ENG
Relevância na Pesquisa
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Although it is widely assumed that temperature affects pollutant toxicity, few studies have actually investigated this relationship. Moreover, such research as has been done has involved constant temperatures; circumstances which are rarely, if ever, actually experienced by north temperate, littoral zone cyprinid species. To investigate the effects of temperature regime on nickel toxicity in goldfish (Carassius auratus L.), 96- and 240-h LCSO values for the heavy metal pollutant, nickel (NiCI2.6H20), were initially determined at 2DoC (22.8 mg/L and 14.7 mg/L in artificially softened water). Constant temperature bioassays at 10°C, 20°C and 30°C were conducted at each of 0, 240-h and 96-h LCSO nickel concentrations for 240 hours. In order to determine the effects of temperature variation during nickel exposure it was imperative that the effects of a single temperature change be investigated before addressing more complex regimes. Single temperature changes of + 10°C or -10°C were imposed at rates of 2°C/h following exposures of between 24 hand 216 h. The effects of a single temperature change on mortality, and duration of toxicant exposure at high and low temperatures were evaluated. The effects of fluctuating temperatures during exposure were investigated through two regimes. The first set of bioassays imposed a sinewave diurnal cycle temperature (20.±.1DOC) throughout the 10 day exposure to 240-h LeSO Ni. The second set of investigations approximated cyprinid movement through the littoral zone by imposing directionally random temperature changes (±2°C at 2-h intervals)...

Influence of temperature on effectiveness of lead arsenate against larvae of the Japanese beetle in the soil

Fleming, Walter E ( Walter Ernest ), 1899-; Maines, Warren W., 1911-; United States -- Bureau of Entomology and Plant Quarantine
Fonte: U.S. Dept. of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine; U.S. Dept. of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine ( [Washington, D.C.] ) Publicador: U.S. Dept. of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine; U.S. Dept. of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine ( [Washington, D.C.] )
Tipo: Artigo de Revista Científica Formato: 11, [12] p. : ill. ; 27 cm.
Publicado em //[1944] ENGLISH
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85.32%
(Bibliography) Includes bibliographical references (p. 11).; Caption title.; "E-622."; "July 1944."; (Statement of Responsibility) by Walter E. Fleming and Warren W. Maines.

Effect of temperature variation on the visible and near infrared spectra of wine and the consequences on the partial least square calibrations developed to measure chemical composition

Cozzolino, D.; Liu, L.; Cynkar, W.; Dambergs, R.; Janik, L.; Colby, C.; Gishen, M.
Fonte: Elsevier Science BV Publicador: Elsevier Science BV
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
75.5%
Many studies have reported the use of near infrared (NIR) spectroscopy to characterize wines or to predict wine chemical composition. However, little is known about the effect of variation in temperature on the NIR spectrum of wine and the subsequent effect on the performance of calibrations used to measure chemical composition. Several parameters influence the spectra of organic molecules in the NIR region, with temperature being one of the most important factors affecting the vibration intensity and frequency of molecular bonds. Wine is a complex mixture of chemical components (e.g. water, sugars, organic acids, and ethanol), and a simple ethanol and water model solution cannot be used to study the possible effects of temperature variations in the NIR spectrum of wine. Ten red and 10 white wines were scanned in triplicate at six different temperatures (25 degrees C, 30 degrees C, 35 degrees C, 40 degrees C, 45 degrees C and 50 degrees C) in the visible (vis) and NIR regions (400-2500 nm) in a monochromator instrument in transmission mode (1 mm path length). Principal component analysis (PCA) and partial least squares (PLS) regression models were developed using full cross validation (leave-one-out). These models were used to interpret the spectra and to develop calibrations for alcohol...

Effect of Temperature on Salt-Salt Aqueous Biphasic Systems: Manifestations of Upper Critical Solution Temperature

Dilip, Meghna; Bridges, Nicholas J.; Rodriguez, Hector; Pereira, Jorge F. B.; Rogers, Robin D.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 454-468
ENG
Relevância na Pesquisa
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Water-miscible ionic liquids (ILs) may be salted out using kosmotropic salts such as potassium phosphate (K3PO4) to form salt-salt aqueous biphasic systems (ABS). The effect of temperature on these systems has been studied using phase diagrams and it is observed that the degree of binodal shift decreases (requiring lower IL and kosmotropic salt concentrations) with the increase of temperature following the trend [C(4)mim]Cl > [C(4)py]Cl > [C(4)mmim] Cl > [N-4444]Cl. This trend can be correlated with the decreasing hydrogen bonding abilities of each salt. The phase behavior was also interpreted on the basis of critical solution temperature behavior of pure aqueous ionic liquid solutions. Additionally, the distribution of alcohols in these systems was studied as a function of temperature and it was found that the distribution ratios did not change with changes in temperature. The Gibbs energy of transfer of a methylene group in these systems and correlation to tie-line length was also determined. It was concluded that while the miscibility of alcohols increases in the ILs with increasing temperature, phase divergence in the aqueous biphasic system decreases, and thus these competing forces tend to cancel each other out for small polar molecules. A comparison is provided for the response to temperature in the currently studied salt-salt systems and analogous ABS formed by the addition of hydrophilic polymers to kosmotropic salts (polymer-salt) or other polymers (polymer-polymer).

The effects of temperature and body mass on jump performance of the locust Locusta migratoria

Snelling, E.; Becker, C.; Seymour, R.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em //2013 EN
Relevância na Pesquisa
75.46%
Locusts jump by rapidly releasing energy from cuticular springs built into the hind femur that deform when the femur muscle contracts. This study is the first to examine the effect of temperature on jump energy at each life stage of any orthopteran. Ballistics and high-speed cinematography were used to quantify the energy, distance, and take-off angle of the jump at 15, 25, and 35°C in the locust Locusta migratoria. Allometric analysis across the five juvenile stages at 35°C reveals that jump distance (D; m) scales with body mass (M; g) according to the power equation D = 0.35M0.17±0.08 (95% CI), jump take-off angle (A; degrees) scales as A = 52.5M0.00±0.06, and jump energy (E; mJ per jump) scales as E = 1.91M1.14±0.09. Temperature has no significant effect on the exponent of these relationships, and only a modest effect on the elevation, with an overall Q10 of 1.08 for jump distance and 1.09 for jump energy. On average, adults jump 87% farther and with 74% more energy than predicted based on juvenile scaling data. The positive allometric scaling of jump distance and jump energy across the juvenile life stages is likely facilitated by the concomitant relative increase in the total length (Lf+t; mm) of the femur and tibia of the hind leg...

Escala diagramática para avaliação da mancha preta em folhas de citros e efeito da temperatura e da duração do molhamento na pré-penetração de conídios de Guignardia citricarpa Kiely [Phyllosticta citricarpa (McAlp.) Van der Aa].; Diagrammatic scale for assessment of citrus black spot in leaves and effect of temperature and wetness duration in the pre-penetration conidia of Guignardia citricarpa Kiely [Phyllosticta citricarpa (McAlp.) Van der Aa].

Noronha, Marissônia de Araujo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 21/01/2003 PT
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85.5%
A mancha preta dos citros causada pelo fungo Guignardia citricarpa Kiely [Phyllosticta citricarpa (McAlp.) Van der Aa], possui duas formas de infecção, conídios e ascósporos. Informações a respeito da importância dos conídios na epidemiologia da doença são escassas ou controversas. Visando uma maior compreensão sobre o patossistema citros-G. citricarpa (P. citricarpa), os objetivos desta dissertação foram: elaborar e validar uma escala diagramática para avaliação da severidade da mancha preta em folhas de citros; verificar o efeito da temperatura e da duração do período de molhamento na formação de apressórios formados a partir de conídios; observar por meio de microscopia eletrônica de varredura a germinação de conídios e a formação de apressórios sobre folhas destacadas de limão 'Siciliano' submetidas a diferentes temperaturas e períodos de molhamento. A escala diagramática com níveis de severidade de 1; 3; 6; 12; e 24% de área foliar lesionada foi validada por dois grupos de avaliadores, com e sem experiência na quantificação de doenças. Comparada com a avaliação sem escala, o uso da escala proporcionou melhor precisão e acurácia tanto para avaliadores experientes como inexperientes, quando considerada a estimativa média dos mesmos. Na maioria dos casos...

The effect of temperature on pollen germination, pollen tube growth, and stigmatic receptivity in peach

Hedhly, Afif; Hormaza Urroz, José Ignacio; Herrero Romero, María
Fonte: Thieme Publicador: Thieme
Tipo: Artículo Formato: 166353 bytes; application/pdf
ENG
Relevância na Pesquisa
75.51%
The definitive version is available at: http://www.thieme.de/fz/plantbiology/; Temperature is a major climatic factor that limits geographical distribution of plant species, and the reproductive phase has proven to be one of the most temperature-vulnerable stages. Here, we have used peach to evaluate the effect of temperature on some processes of the progamic phase, from pollination to the arrival of pollen tubes in the ovary. Within the range of temperatures studied, 20 °C in the laboratory and, on average, 5.7 °C in the field, the results show an accelerating effect of increasing temperature on pollen germination and pollen tube growth kinetics, as well as an increase in the number of pollen tubes that reach the style base. For the last two parameters, although the range of temperature registered in the field was much lower, the results obtained in the laboratory paralleled those obtained in the field. Increasing temperatures drastically reduced stigmatic receptivity. Reduction was sequential, with stigmas first losing the capacity to sustain pollen tube penetration to the transmitting tissue, then their capacity to offer support for pollen germination and, finally, their capacity to support pollen grain adhesion. Within a species-specific range of temperature...

Effect of temperature on pollen tube kinetics and dynamics in sweet cherry, Prunus avium (Rosaceae)

Hedhly, Afif; Hormaza Urroz, José Ignacio; Herrero Romero, María
Fonte: Botanical Society of America Publicador: Botanical Society of America
Tipo: Artículo Formato: 112851 bytes; application/pdf
ENG
Relevância na Pesquisa
85.47%
The article is available at: http://www.amjbot.org/cgi/content/full/91/4/558; Prevailing ambient temperature during the reproductive phase is one of several important factors for seed and fruit set in different plant species, and its consequences on reproductive success may increase with global warming. The effect of temperature on pollen performance was evaluated in sweet cherry (Prunus avium L.), comparing as pollen donors two cultivars that differ in their adaptation to temperature. ‘Sunburst’ is a cultivar that originated in Canada with a pedigree of cultivars from Northern Europe, while ‘Cristobalina’ is a cultivar native to southeast Spain, adapted to warmer conditions. Temperature effects were tested either in controlled-temperature chambers or in the field in a plastic cage. In both genotypes, an increase in temperature reduced pollen germination, but accelerated pollen tube growth. However, a different genotypic response, which reflected the overall adaptation of the pollen donor, was obtained for pollen tube dynamics, expressed as the census of the microgametophyte population that successfully reached the base of the style. While both cultivars performed similarly at 20°C, the microgametophyte population was reduced at 30°C for Sunburst and at 10°C for Cristobalina. These results indicate a differential genotypic response to temperature during the reproductive phase...

The effects of atmospheric and oceanic conditions on the stability of ice bridges

Stelma, Sigourney Anne
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
Relevância na Pesquisa
85.51%
Huntley, Helga; Ice bridges are arch-like ice structures that form in narrow passages and straits. These bridges play largely important roles in the circulation of Arctic sea ice. When an ice bridge is present in a strait, there is typically a stoppage of sea ice flow, and there generally little ice flow downstream from the bridge. Nares Strait, located between Ellesmere Island and Greenland, allows for Arctic sea ice to be exported into the Atlantic Ocean. Ice bridges typically form in Nares Strait, which causes a stoppage of this export. This stoppage allows for Arctic sea ice to grow thicker, which is important for our current climate. Building on studies that examined the formation of ice bridges, this study aims to model and analyze the destruction of ice bridges. Using CICE: The Los Alamos Sea Ice Model, ice bridges are modeled in an idealized strait that is geographically and dimensionally similar to Nares Strait. The bridges are allowed to strengthen for 7 days past their initial formation. Then various atmospheric and oceanic parameters are changed, to examine their effect on the stable ice bridges. All parameter changes are applied over the entire domain and are constant in time. Extreme temperatures are used to study the effect of temperature. Then various amounts of longwave and shortwave radiation are tested independently...

The effects of temperature, CO2, and nitrogen source on the growth and physiology of the raphidophytes Heterosigma akashiwo and Chattonella subsalsa

Salvitti, Lauren
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
Relevância na Pesquisa
75.52%
Warner, Mark E.; During the past three decades the frequency and duration of harmful algal blooms (HABs) have significantly increased causing major economical losses world wide as well as being identified as the cause of a number of human health illnesses. These impacts have brought harmful algal species to the forefront of research efforts which are focused primarily on the effects of abiotic and biotic factors on algal growth. Less effort has been placed on understanding how changes in environmental parameters may impact harmful algal physiology. The effects of elevated CO2 and temperature were studied using the raphidophytes Chattonella subsalsa and Heterosigma akashiwo isolated from the Delaware Inland Bays (DIB), and a cold water isolate of H. akashiwo from Puget Sound, WA. Neither increases in temperature, CO2, or a combined treatment of elevated temperature and CO2, had any significant effect on the growth rates of all three isolates. However, significant changes in physiology and carbon uptake were seen among temperature/CO2 treatments and between strains. Both isolates of H. akashiwo exhibited changes in light harvesting capabilities in response to temperature, with a decrease in maximum carbon assimilation occurring in the cold water isolate. In contrast both elevated temperature and CO2 altered the physiology of C. subsalsa although changes were not additive. Carbon assimilation increased in response to elevated CO2 while temperature had a greater effect on light harvesting in this species. While growth and cell size did not change across any treatments in these raphidophytes...

Effect of temperature on development and survival in Delias nigrina (Fabricius) (Lepidoptera: Pieridae)

Braby, Michael; Lyonns, Kelly
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
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75.46%
The effect of temperature on rate of development and survival of the immature stages of a subtropical population of the black jezebel, Delias nigrina, was studied under laboratory conditions at a range of constant temperatures. Mean developmental times from first-instar larva to adult varied from 29 days at 27°C to 52 days at 19°C; the development threshold temperature and thermal constant were estimated to be 9°C and 494 degree-days, respectively. Larval developmental rates reached physiological maximum at the higher temperatures tested (25-27°C). Pupal development, by contrast, was not affected in the same way as larvae by higher temperature. Survival of the immature stages varied inversely with temperature: survival was highest at 19°C and significantly reduced at 27°C. Mortality at the higher temperature was attributable mainly to final-instar larvae and pupae. These findings indicate that, compared with other tropical pierids that have been studied, D. nigrina has: (i) a comparatively low temperature threshold; (ii) a slow rate of development; and (iii) a poor tolerance to moderately high temperatures. Physiologically, these features are more characteristic of a temperate butterfly than a tropical one. This physiological response appears to be reflected by the temperate nature of the genus as a whole...

Effect of temperature on the development time and survival of preimaginal Culex hepperi (Diptera: Culicidae)

Loetti,María Verónica; Burroni,Nora E.; Prunella,Paula; Schweigmann,Nicolás
Fonte: Revista de la Sociedad Entomológica Argentina Publicador: Revista de la Sociedad Entomológica Argentina
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
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The aim of this research was to evaluate the effect of temperature on the development time and survival of Culex (Culex) hepperi Casal and García, 1967. Individuals were reared in the laboratory, from the first larval stage to adult emergence, at five constant temperatures: 15, 20, 25, 30, and 33°C. The total development time was inversely related to temperature between 15 and 25°C. No differences were observed in the development time between sexes and no adults emerged at 33°C. In the larval stages III and IV, the time required for molting to the next stage increased at 30°C. The highest survival was recorded at 20°C. The more developed stages were less resistant to temperatures above and below 20°C. According to the nonlinear model of Briére, the lower and upper development thresholds were 2.6 and 33°C, respectively. Our results suggest that the effect of temperature depends upon the stage of development of C. hepperi.

Effect of temperature on the expression of IFN-1 (α), STAT-1 and Mx-1 genes in Oncorhynchus mykiss (Salmoniformes: Salmonidae) exposed with the virus of the infectious pancreatic necrosis (IPNV)

Arguedas Cortés,Donald; Romero Zuñiga,Alex P.; Enriquez Sais,Ricardo; Martínez Castañeda,José S.; Ortega Santana,César
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2015 EN
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The infectious pancreatic necrosis (IPNV) is the causative agent of an acute illness well characterized in salmonids worldwide. Clinical signs and mortality rates are dependent on several factors such as the viral dose, the age of the fish, the water temperature, among others. An experimental study was conducted to measure the effect of temperature on the gene expression profile of IFN-1(α), STAT-1 and Mx-1 in rainbow trout fry, exposed to IPNV. Fry (n=198) were exposed at 8, 12 and 16°C, and samples were taken for 21 days to determine the virus titer and gene expression. In the first 11 days the greatest viral titer was recorded at 8°C compared with the values obtained at 12 and 16°C. At 8°C, there was a significant increase on day 4 of mRNA Mx-1 (t-test, p<0.05), time in which the viral titer began to decrease. Furthermore, as the viral titer increased, STAT-1 and Mx-1 (r=0.91) and (r=0.96) increased, respectively. The animals were able to recover from day 4 from some of the symptoms of IPN. Clinical disease was developed only in fish exposed to 12°C and all died between days 6 and 14, despite the highly significant increase shown in the average expression level of Mx-1, compared with the values recorded at 8°C and 16°C (Tukey...