Relationships of photosynthetic photon flux density, air temperature and humidity with tomato leaf diffusive conductance and temperature

The objective was to study the leaf temperature (LT) and leaf diffusive vapor conductance (gs) responses to temperature, humidity and incident flux density of photosynthetically active photons (PPFD) of tomato plants grown without water restriction in a plastic greenhouse in Santa Maria, RS, Brazil. The plants were grown in substrate and irrigated daily. The gs was measured using a steady-state null-balance porometer on the abaxial face of the leaves during the daytime. Both leaf surfaces were measured in one day. The PPFD and LT were measured using the porometer. Leaf temperature was determined using an infrared thermometer, and air temperature and humidity were measured using a thermohygrograph. The leaves on the upper layer of the plants had higher gs than the lower layer. The relationship between the gs and PPFD was different for the two layers in the plants. A consistent relationship between the gs and atmospheric water demand was observed only in the lower layer. The LT tended to be lower than the air temperature. The mean value for the gs was 2.88 times higher on the abaxial than adaxial leaf surface.

Influence of growth media and temperature on bacterial adhesion to polystyrene surfaces

Bacterial adhesion to inert surfaces is a complex process influenced by environmental conditions. In this work, the influence of growth medium and temperature on the adhesion of Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, Micrococcus luteus and Listeria monocytogenes to polystyrene surfaces was studied. Most bacteria demonstrated the highest adhesion when cultured in TSYEA, except S. marcescens, which showed to be positively influenced by the pigment production, favored in poor nutrient media (lactose and peptone agar). P. aeruginosa adhesion to polystyrene increased at low temperatures whatever the medium used. The culture medium influenced the surface properties of the bacteria as assessed by the MATS test.

Seasonality of viral respiratory infections in Southeast of Brazil: the influence of temperature and air humidity

Viruses are the major cause of lower respiratory tract infections in childhood and the main viruses involved are Human Respiratory Syncytial Virus (HRSV), Human Metapneumovirus (HMPV), Influenzavirus A and B (FLUA and FLUB), Human Parainfluenza Virus 1, 2 and 3 (HPIV1, 2 and 3) and Human Rhinovirus (HRV). The purposes of this study were to detect respiratory viruses in hospitalized children younger than six years and identify the influence of temperature and relative air humidity on the detected viruses. Samples of nasopharyngeal washes were collected from hospitalized children between May/2004 and September/2005. Methods of viral detection were RT-PCR, PCR and HRV amplicons were confirmed by hybridization. Results showed 54% (148/272) of viral positivity. HRSV was detected in 29% (79/272) of the samples; HRV in 23.1% (63/272); HPIV3 in 5.1% (14/272); HMPV in 3.3% (9/272); HPIV1 in 2.9% (8/272); FLUB in 1.4% (4/272), FLUA in 1.1% (3/272), and HPIV2 in 0.3% (1/272). The highest detection rates occurred mainly in the spring 2004 and in the autumn 2005. It was observed that viral respiratory infections tend to increase as the relative air humidity decreases, showing significant association with monthly averages of minimal temperature and minimal relative air humidity. In conclusion, viral respiratory infections vary according to temperature and relative air humidity and viral respiratory infections present major incidences it coldest and driest periods.

Prediction of the temperature distribution of partially submersed umbilical cables

The objective of this work is to predict the temperature distribution of partially submersed umbilical cables under different operating and environmental conditions. The commercial code Fluent® was used to simulate the heat transfer and the air fluid flow of part of a vertical umbilical cable near the air-water interface. A free-convective three-dimensional turbulent flow in open-ended vertical annuli was solved. The influence of parameters such as the heat dissipating rate, wind velocity, air temperature and solar radiation was analyzed. The influence of the presence of a radiation shield consisting of a partially submersed cylindrical steel tube was also considered. The air flow and the buoyancydriven convective heat transfer in the annular region between the steel tube and the umbilical cable were calculated using the standard k-ε turbulence model. The radiative heat transfer between the umbilical external surface and the radiation shield was calculated using the Discrete Ordinates model. The results indicate that the influence of a hot environment and intense solar radiation may affect the umbilical cable performance in its dry portion.

Fermentative production of ribonucleotides from whey by Kluyveromyces marxianus: effect of temperature and pH

Ribonucleotides have shown many promising applications in food and pharmaceutical industries. The aim of the present study was to produce ribonucleotides (RNA) by Kluyveromyces marxianus ATCC 8,554 utilizing cheese whey, a dairy industry waste, as a main substrate under batch fermentation conditions. The effects of temperature, pH, aeration rate, agitation and initial cellular concentration were studied simultaneously through factorial design for RNA, biomass production and lactose consumption. The maximum RNA production (28.66 mg/g of dry biomass) was observed at temperature 30°C, pH 5.0 and 1 g/l of initial cellular concentration after 2 h of fermentation. Agitation and aeration rate did not influence on RNA concentration (p >0.05). Maximum lactose consumption (98.7%) and biomass production (6.0 g/l) was observed after 12 h of incubation. This study proves that cheese whey can be used as an adequate medium for RNA production by K. marxianus under the optimized conditions at industrial scale.

Natural blood feeding and temperature shift modulate the global transcriptional profile of Rickettsia rickettsii infecting its tick vector

Rickettsia rickettsii is an obligate intracellular tick-borne bacterium that causes Rocky Mountain Spotted Fever (RMSF), the most lethal spotted fever rickettsiosis. When an infected starving tick begins blood feeding from a vertebrate host, R. rickettsii is exposed to a temperature elevation and to components in the blood meal. These two environmental stimuli have been previously associated with the reactivation of rickettsial virulence in ticks, but the factors responsible for this phenotype conversion have not been completely elucidated. Using customized oligonucleotide microarrays and high-throughput microfluidic qRT-PCR, we analyzed the effects of a 10 degrees C temperature elevation and of a blood meal on the transcriptional profile of R. rickettsii infecting the tick Amblyomma aureolatum. This is the first study of the transcriptome of a bacterium in the genus Rickettsia infecting a natural tick vector. Although both stimuli significantly increased bacterial load, blood feeding had a greater effect, modulating five-fold more genes than the temperature upshift. Certain components of the Type IV Secretion System (T4SS) were up-regulated by blood feeding. This suggests that this important bacterial transport system may be utilized to secrete effectors during the tick vector's blood meal. Blood feeding also up-regulated the expression of antioxidant enzymes, which might correspond to an attempt by R. rickettsii to protect itself against the deleterious effects of free radicals produced by fed ticks. The modulated genes identified in this study, including those encoding hypothetical proteins, require further functional analysis and may have potential as future targets for vaccine development.

The impact of rising sea temperature on innate immune parameters in the tropical subtidal sea urchin Lytechinus variegatus and the intertidal sea urchin Echinometra lucunter

Ocean temperatures are rising throughout the world, making it necessary to evaluate the impact of these temperature changes on sea urchins, which are well-known bioindicators. This study evaluated the effect of an increase in temperature on the immune response of the subtidal Lytechinus variegatus and the intertidal Echinometra lucunter sea urchins. Both species were exposed to 20 (control), 25 and 30 °C temperatures for 24 h, 2, 7 and 14 days. Counting of coelomocytes and assays on the phagocytic response, adhesion and spreading of coelomocytes were performed. Red and colorless sphere cells were considered biomarkers for heat stress. Moreover, a significant decrease in the phagocytic indices and a decrease in both cell adhesion and cell spreading were observed at 25 and 30 °C for L. variegatus. For E. lucunter, the only alteration observed was for the cell proportions. This report shows how different species of sea urchins respond immunologically to rising temperatures

Measurement and model calculation of the temperature dependence of ligand-to-metal energy transfer rates in lanthanide complexes

Temperature dependent transient curves of excited levels of a model Eu3+ complex have been measured for the first time. A coincidence between the temperature dependent rise time of the 5D0 emitting level and decay time of the 5D1 excited level in the [Eu(tta)3(H2O)2] complex has been found, which unambiguously proves the T1→5D1→5D0 sensitization pathway. A theoretical approach for the temperature dependent energy transfer rates has been successfully applied to the rationalization of the experimental data.

Studies of Inorganic Layer and Framework Structures Using Time-, Temperature- and Pressure-Resolved Powder Diffraction Techniques

This thesis is concerned with in-situ time-, temperature- and pressure-resolved synchrotron X-ray powder diffraction investigations of a variety of inorganic compounds with twodimensional layer structures and three-dimensional framework structures. In particular, phase stability, reaction kinetics, thermal expansion and compressibility at non-ambient conditions has been studied for 1) Phosphates with composition MIV(HPO4)2·nH2O (MIV = Ti, Zr); 2) Pyrophosphates and pyrovanadates with composition MIVX2O7 (MIV = Ti, Zr and X = P, V); 3) Molybdates with composition ZrMo2O8. The results are compiled in seven published papers and two manuscripts. Reaction kinetics for the hydrothermal synthesis of α-Ti(HPO4)2·H2O and intercalation of alkane diamines in α-Zr(HPO4)2·H2O was studied using time-resolved experiments. In the high-temperature transformation of γ-Ti(PO4)(H2PO4)·2H2O to TiP2O7 three intermediate phases, γ'-Ti(PO4)(H2PO4)·(2-x)H2O, β-Ti(PO4)(H2PO4) and Ti(PO4)(H2P2O7)0.5 were found to crystallise at 323, 373 and 748 K, respectively. A new tetragonal three-dimensional phosphate phase called τ-Zr(HPO4)2 was prepared, and subsequently its structure was determined and refined using the Rietveld method. In the high-temperature transformation from τ-Zr(HPO4)2 to cubic α-ZrP2O7 two new orthorhombic intermediate phases were found. The first intermediate phase, ρ-Zr(HPO4)2, forms at 598 K, and the second phase, β-ZrP2O7, at 688 K. Their respective structures were solved using direct methods and refined using the Rietveld method. In-situ high-pressure studies of τ-Zr(HPO4)2 revealed two new phases, tetragonal ν-Zr(HPO4)2 and orthorhombic ω-Zr(HPO4)2 that crystallise at 1.1 and 8.2 GPa. The structure of ν-Zr(HPO4)2 was solved and refined using the Rietveld method. The high-pressure properties of the pyrophosphates ZrP2O7 and TiP2O7, and the pyrovanadate ZrV2O7 were studied up to 40 GPa. Both pyrophosphates display smooth compression up to the highest pressures, while ZrV2O7 has a phase transformation at 1.38 GPa from cubic to pseudo-tetragonal β-ZrV2O7 and becomes X-ray amorphous at pressures above 4 GPa. In-situ high-pressure studies of trigonal α-ZrMo2O8 revealed the existence of two new phases, monoclinic δ-ZrMo2O8 and triclinic ε-ZrMo2O8 that crystallises at 1.1 and 2.5 GPa, respectively. The structure of δ-ZrMo2O8 was solved by direct methods and refined using the Rietveld method.

Effect of temperature and food concentration on the relationship between growth and AARS activity in Paracartia grani nauplii

[EN]The in situ activity of the enzymes aminoacyl-tRNA synthetases (AARS) and the growth rates of naupliar stages of the planktonic marine copepod Paracartia grani were measured in the laboratory under different temperature and food concentrations. We assessed the effect of these parameters on growth and protein synthesis rates of P. grani nauplii. Growth and protein synthesis rates of P. grani nauplii depended on temperature and food concentration. AARS activity is valid as index of somatic growth for P. grani nauplii when growth is not limited by food availability. However, the relationship between protein-specific AARS activity and nauplii growth varied according to food availability levels. The degradation of proteins during starvation and/or the ß-oxidation of fatty acids affected the relationship between specific AARS activity and growth rates. The results presented here add to previous studies showing that the AARS activity is a useful tool for estimating somatic growth of this and other key copepod species. Nevertheless, further research is required to elucidate the validity of AARS activity as a universal proxy for growth.

Effect of temperature and food concentration on the relationship between growth

[EN] The in situ activity of the enzymes aminoacyl-tRNA synthetases (AARS) and the growth rates of naupliar stages of the planktonic marine copepod Paracartia grani were measured in the laboratory under different temperature and food concentrations. We assessed the effect of these parameters on growth and protein synthesis rates of P. grani nauplii. Growth and protein synthesis rates of P. grani nauplii depended on temperature and food concentration. AARS activity is valid as an index of somatic growth for P. grani nauplii when growth is not limited by food availability. However, the relationship between protein-specific AARS activity and nauplii growth varied according to food availability levels. The degradation of proteins during starvation and/or the ß-oxidation of fatty acids affected the relationship between specific AARS activity and growth rates. The results presented here add to previous studies showing that the AARS activity is a useful tool for estimating somatic growth of this and other key copepod species. Nevertheless, further research is required to elucidate the validity of AARS activity as a universal proxy for growth.

Recent changes in subsurface temperature and salinity in the Canary region

[EN]Based on hydrographic sections carried out during the last decade in the Canary region at 29° 10′N, we show that there has been a statistically significant rise in temperature and salinity on isobars between 1500 and 2300 db. The maximum increase, found at 1600 db, is occurring at a rate of 0.29°C and 0.047 per decade. Isobaric change decomposition into changes on neutral surfaces and changes due to the vertical displacement of the isoneutrals was performed. Results reveal that the lower part of North Atlantic Central Water (NACW) cooled and freshened on neutral surfaces, suggesting changes in the freshwater fluxes at the outcropping region. However, the signal in deep waters (1500–2300 db) was principally due to a downward displacement of the isoneutrals, although water mass modification is observed in the range of Mediterranean Water (MW) influence.