scholarly journals Ageing of Some Lacquers Due to Microbiological Stress

2019 ◽  
Vol 56 (2) ◽  
pp. 330-336
Author(s):  
Adriana-Mariana Bors ◽  
Marius-Eduard Lungulescu ◽  
Nicoleta Oana Nicula (Butoi) ◽  
Alina-Ruxandra Caramitu ◽  
Iosif Lingvay
Keyword(s):  
Epoxy Polymer ◽  
Oxidation Process ◽  
Volume Resistivity ◽  
Dielectric Losses ◽  
Fungal Attack ◽  
Ageing Study ◽  
Temperature Ranges ◽  
The Mean ◽  
Dsc Thermograms ◽  
Major Oxidation

This paper shows the ageing study of some coatings and / or impregnation lacquers due to microbiological stress through fungal attack. Dielectric spectroscopy has shown that the dielectric losses of the investigated materials increase as result of microbiological ageing. The mean recorded increases are about 4 times for the alkyl-epoxy-melamine copolymer, 2 times for epoxy polymer and 1.5 times for urethane polymer in agreement with the mould coverage degree of about 20 %, 10 %, and 3 %, respectively. The fungal attack of the investigated polymers led to a decrease in volume resistivity of about 65 % for the alkyl-epoxy-melamine copolymer, 45 % for the epoxy polymer, and 14 % for polyurethane, in agreement with the increase of dielectric losses and degree of mold coverage of the samples. FTIR determinations have shown that fungal attack significantly increased the number of aliphatic -OH and C-H bonds and decreased the number of C-O bonds, respectively of C-O-C oxiran groups and C-C aromatic bonds. DSC thermograms recorded at different temperature ranges and the activation energies calculation for first major oxidation process indicate that after the fungal attack the thermooxidative reactivity of the investigated polymers increases.

scholarly journals The volume coefficients of expansion of several gases at pressures below one metre

1934 ◽  
Vol 143 (850) ◽  
pp. 487-505 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Linear Function ◽  
Rate Of Change ◽  
Linear Extrapolation ◽  
Satisfactory Explanation ◽  
Volume Coefficient ◽  
Temperature Ranges ◽  
The Mean ◽  
Permanent Gases ◽  
Limiting Value

There have not appeared recently any new determinations of the rate of change of the volume coefficient of expansion of condensable gases at pressures in the neighbourhood of a half to one metre. The work of Henning and Heuse and Heuse and Otto has been confined to a study of the permanent gases, their results leading to the conclusion that up to a pressure of 1 metre the rate of change of either the pressure or volume coefficient is a linear function of the pressure. Our knowledge of the behaviour of the condensable gases in this connection rests almost entirely on the very careful work of Chappuis, who in 1907 made a series of accurate determinations of the volume coefficient of expansion of carbon dioxide at a series of pressures from 1500 mm. to 500 mm. and over several temperature ranges. The investigation led to one unexpected conclusion which Chappuis left largely unexplained. On linear extrapolation to zero pressure of the graph of pressure against the mean coefficient of expansion over temperature intervals 0-20º, 0-40º, 0-100ºC., the limiting value of the coefficient rose from the normal value of 0.003661 for the 0-20º determinations to 0.003671 for those made over the range 0-100ºC. Chappuis concludes "that condensation on the reservoir surface plays a part in the irregularities but it is difficult to obtain a satisfactory explanation." As far back as 1853 Magnus demonstrated that the adsorption of sukphur dioxide on glass was sufficient to affect measurements of the expansion coefficient of gasses, and the importance of this error was recognized by Chappuis who in 1879 applied a correction to Regnault's measurements. Richards and Mark and Baly and Ramsay have pointed out the necessity for a knowledge of the amount of adsorption on the walls of the containing vessels when undertaking such determinations.

scholarly journals Methane dynamics in different boreal\\newline lake types

2008 ◽  
Vol 5 (4) ◽  
pp. 3457-3496 ◽  
Author(s):  
S. Juutinen ◽  
M. Rantakari ◽  
P. Kortelainen ◽  
J. T. Huttunen ◽  
T. Larmola ◽  
...  
Keyword(s):  
Surface Water ◽  
Shallow Lakes ◽  
Nutrient Concentrations ◽  
Temperature Ranges ◽  
Lake Status ◽  
Different Depths ◽  
Ch4 Concentration ◽  
The Mean ◽  
Annual Flux ◽  
The Eu

Abstract. This study explores the variability in concentrations of dissolved CH4 and annual flux estimates in the pelagic zone in a statistically defined sample of 207 lakes in Finland. The lakes were situated representatively in the boreal zone, where the mean annual air temperature ranges from −2.8 to 5.9°C. We examined how lake CH4 dynamics related to regional lake types assessed according to the EU water framework directive. Ten lake types were defined on the basis of water chemistry, color, and size. Lakes were sampled for dissolved CH4 concentrations four times per year, at four different depths at the deepest point of each lake. We found that CH4 concentrations and fluxes to the atmosphere tended to be high in nutrient rich calcareous lakes, and that the shallow lakes had the greatest surface water concentrations. CH4 content in the hypolimnion was related to oxygen and nutrient concentrations, and lake depth or area. The surface water CH4 concentration was related to the depth or area of lake. Methane close to the bottom can be viewed as proxy of lake status in terms of frequency of anoxia and nutrient levels. Median CH4 release from randomly selected lakes was 45 mmol m−2 a−1. Shallow lakes had the highest median CH4 effluxes, with the clear shallow lake type having the smallest median. Our data, combined with other studies, suggest that lake surface area could be used for an approximation of CH4 release from lakes. Shallow small lakes common in boreal and arctic landscapes may have disproportional significance with respect to CH4 release.

scholarly journals Thermal annealing of implanted <sup>252</sup>Cf fission tracks in monazite

Geochronology ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 89-102
Author(s):  
Sean Jones ◽  
Andrew Gleadow ◽  
Barry Kohn
Keyword(s):  
Thermal Annealing ◽  
Fission Track ◽  
Closure Temperature ◽  
Fission Tracks ◽  
Temperature Ranges ◽  
Best Fitting ◽  
The Mean ◽  
Oriented Parallel ◽  
Increasing Temperature ◽  
Ambient Surface

Abstract. A series of isochronal heating experiments were performed to constrain monazite fission track thermal annealing properties. The 252Cf fission tracks were implanted into monazite crystals from the Devonian Harcourt granodiorite (Victoria, Australia) on polished surfaces oriented parallel to (100) pinacoidal faces and perpendicular to the crystallographic c axis. Tracks were annealed over 1, 10, 100 and 1000 h schedules at temperatures between 30 and 400 ∘C. Track lengths were measured on captured digital image stacks and then converted to calculated mean lengths of equivalent confined fission tracks that progressively decreased with increasing temperature and time. Annealing is anisotropic, with tracks on surfaces perpendicular to the crystallographic c axis consistently annealing faster than those parallel to the (100) face. To investigate how the mean track lengths decreased as a function of annealing time and temperature, one parallel and two fanning models were fitted to the empirical dataset. The temperature limits of the monazite partial annealing zone (MPAZ) were defined as length reductions to 0.95 (lowest) and 0.5 (highest) for this study. Extrapolation of the laboratory experiments to geological timescales indicates that for a heating duration of 107 years, estimated temperature ranges of the MPAZ are −44 to 101 ∘C for the parallel model and −71 to 143 ∘C (both ±6–21 ∘C, 2 standard errors) for the best-fitting linear fanning model (T0=∞). If a monazite fission track closure temperature is approximated as the midpoint of the MPAZ, these results, for tracks with similar mass and energy distributions to those involved in spontaneous fission of 238U, are consistent with previously estimated closure temperatures (calculated from substantially higher energy particles) of < 50 ∘C and perhaps not much higher than ambient surface temperatures. Based on our findings we estimate that this closure temperature (Tc) for fission tracks in monazite ranges between ∼ 45 and 25 ∘C over geological timescales of 106–107 years, making this system potentially useful as an ultra-low-temperature thermochronometer.

Soil temperature regime in a forested Appalachian watershed

1986 ◽  
Vol 16 (3) ◽  
pp. 624-629 ◽  
Author(s):  
S. J. Tajchman ◽  
C. M. Minton
Keyword(s):  
Surface Temperature ◽  
Soil Temperature ◽  
Soil Layer ◽  
The North ◽  
Soil Temperature Regime ◽  
Temperature Ranges ◽  
The Mean ◽  
The Difference ◽  
Topographic Positions ◽  
Lower Slope

Daily and seasonal variations in soil temperature at various topographic positions in a forested catchment are compared. The experimental sites were designed as ridgetop, north-facing lower slope, south-facing lower slope, and southwest-facing slope. On sunny days during the growing season, the surface temperature had the greatest amplitude (7.8 °C) at the south-facing upper slope and the smallest amplitude (4.0 °C) at the north-facing slope; the remaining sites were intermediate. The maximum surface temperature was observed in the afternoon at all sites. With increasing depth, daily soil temperature ranges diminished and, below 10 cm depth, they were less than 1 °C. Under overcast conditions, daily soil temperature fluctations lessened. For individual months, the mean temperatures of the 2–30 cm soil layer generally varied among all sites by less than 1 °C and never the difference exceeded 1.8 °C. The surface temperature variations and their differences among sites appear to be the most distinguished feature of the soil thermal regime and they seem to be aspect related.

scholarly journals Thermal Annealing of Implanted <sup>252</sup>Cf Fission-1 Tracks in Monazite

2020 ◽  
Author(s):  
Sean Jones ◽  
Andrew Gleadow ◽  
Barry Kohn
Keyword(s):  
Thermal Annealing ◽  
Fission Track ◽  
Energy Distributions ◽  
Fission Tracks ◽  
Temperature Ranges ◽  
Best Fitting ◽  
The Mean ◽  
Oriented Parallel ◽  
Increasing Temperature ◽  
Partial Annealing

Abstract. A series of isochronal heating experiments were performed to constrain monazite fission-track thermal annealing properties. 252Cf fission-tracks were implanted into monazite crystals from the Devonian Harcourt Granodiorite (Victoria, Australia) on polished surfaces oriented parallel and perpendicular to (100) prismatic faces. Tracks were annealed over 1, 10, 100 and 1000 hour schedules at temperatures between 30 °C and 400 °C. Track lengths were measured on captured digital image stacks, and then converted to calculated mean lengths of equivalent confined fission tracks which progressively decreased with increasing temperature and time. Annealing is anisotropic, with tracks on surfaces perpendicular to the crystallographic c-axis consistently annealing faster than those on surfaces parallel to c. To investigate how the mean track lengths decreased as a function of annealing time and temperature, one parallel and two fanning models were fitted to the empirical dataset. The temperature limits of the monazite partial annealing zone (MPAZ) were defined as length reductions to 0.95 (lowest) and 0.5 (highest) for this study. Extrapolation of the laboratory experiments to geological timescales indicates that for a heating duration of 107 years, estimated temperature ranges of the MPAZ are −44 to 101 °C for the parallel model and −71 to 143 °C (both ~ 6–21 °C, 2 standard errors) for the best fitting linear fanning model (T0 = ∞). If a monazite fission-track closure temperature is approximated as the mid-point of the MPAZ, these results, for tracks with similar mass and energy distributions to those involved in spontaneous fission of 238U, are consistent with previously estimated closure temperatures (calculated from substantially higher energy particles) of

scholarly journals Analysis of Decadal Rainfall and Temperature Trend in Warri, Nigeria

2021 ◽  
Vol 2 (2) ◽  
pp. 15-18
Author(s):  
Oyeleke Oluwaseun Oyerinde
Keyword(s):  
Temperature Trend ◽  
Monthly Rainfall ◽  
Rainfall Data ◽  
Annual Rainfall ◽  
Total Rainfall ◽  
Monthly Temperature ◽  
Increasing Trend ◽  
Temperature Ranges ◽  
The Mean ◽  
Using Data

This study investigates rainfall and temperature trend in Warri, Delta State, Nigeria using data derived from Nigerian Meteorological Agency between 2005 and 2015. Data was analyzed to reveal trend in temperature and rainfall values in the years under study and to determine whether there were significant variations. Analysis of rainfall data shows that 2007 had the lowest total rainfall over the 11 year period with a total annual rainfall of 2030.58 mm while 2015 was the year with the highest annual rainfall record of 3183.6 mm. The mean monthly Rainfall indicates that January has the lowest record of rainfall with a total of 36.9 mm while July is the month with highest value of 423.2 mm. Results further indicates that June has the lowest mean monthly temperature over the 11 year period of 20 ºC while March has the highest record of 29.6 ºC. Dominant temperature ranges between 26.1 oC and 26.8 ºC closely followed by 27.7–28.4 ºC which are quite close to the mean monthly values in the area. Analysis of rainfall data confirms an increasing trend.

Isotope Thermotransport in Liquid Potassium, Rubidium, and Gallium

1966 ◽  
Vol 21 (9) ◽  
pp. 1344-1347 ◽  
Author(s):  
A. Lodding ◽  
A. Ott
Keyword(s):  
Theoretical Model ◽  
Liquid Metal ◽  
Free Volume ◽  
Thermal Diffusion ◽  
Isotope Separation ◽  
Light Isotope ◽  
Statistical Fluctuations ◽  
Temperature Ranges ◽  
The Mean ◽  
Effective Cluster

Temperature differences ranging from 100°C to 500°C were maintained between the top and bottom ends of vertical capillaries containing liquid metal. The light isotope was found to be enriched at the hot end. The steady-sate isotope separation for different temperature ranges were between 1 and 3 per cent, corresponding to the thermal diffusion factors αK=3.1×10-2, αRb=3.1 × 10-2 and αGa=3.8 × 10 -2. According to a theoretical model, the results imply that the diffusing species is a “cluster” of several cooperating atoms, the mean diffusive displacement of which is considerably less than the effective cluster diameter. The clusters drift into voids given by the statistical fluctuations of free volume.

scholarly journals Technology and Electrophysical Properties of Multiferroic PZT–PFT Ceramics

2013 ◽  
Vol 58 (4) ◽  
pp. 1361-1364 ◽  
Author(s):  
P. Niemiec ◽  
R. Skulski ◽  
D. Bochenek ◽  
P. Wawrzała
Keyword(s):  
Dielectric Permittivity ◽  
Room Temperature ◽  
Ferroelectric Phase ◽  
Hysteresis Loops ◽  
Wide Distribution ◽  
Ceramic Technology ◽  
Dielectric Losses ◽  
Dielectric Measurements ◽  
Ceramic Samples ◽  
The Mean

Abstract We present the results of obtaining and investigating ceramic samples of solid solution (1-x)(PbZr0.53Ti0.47O3)- x(PbFe0.5Ta0.5O3) [i.e. (1-x)PZT-xPFT] with x =0.25, 0.35 and 0.45 obtained using conventional ceramic technology. These materials belong to class of materials known as multiferroics. Solid solutions PZT-PFT are the lowest-loss room-temperature multiferroics known, and as a result there are very interesting for magnetoelectric devices. Paper presents the results of termogravimetric investigations, EDS, XRD and main dielectric measurements. It has been stated that with increasing content of PFT decreases the mean diameter of grains and more wide distribution of grain diameters is observed. For x =0.25 sharp phase transition from ferroelectric phase to paraelectric one is observed and high values of dielectric permittivity. Composition PZT-PFT with x =0.45 has the lowest values of dielectric permittivity, and the transition is more diffused. The increase of x leads also to the shift of the temperature of maximum of dielectric permittivity towards lower temperatures. Samples with x =0.25 and x =0.35 exhibit very low values of dielectric losses up to about 100°C. Dielectric losses for samples with x =0.45 are higher. For obtained PZT-PFT samples we have investigated P-E hysteresis loops at room temperature for frequency 1 Hz. For composition x =0.25 it after application the field about 2.5 kV/mm polarization is equal approximately 28 μC/cm2, while for x =0.35, and x =0.45 after application the field about 2.0 kV/mm the polarizations are equal about 25 μC/cm2 and 20 μC/cm2 respectively. Very low values of losses and high values of polarization lead to the conclusion that interesting material PZT-PFT for applications should be composition with x =0.25.

scholarly journals Comparisons of Temperature Measurements from Local Weather Stations and the Tomato Plant Canopy: Implications for Crop and Pest Forecasting

1990 ◽  
Vol 115 (5) ◽  
pp. 861-869 ◽  
Author(s):  
Nita A. Davidson ◽  
L. Theodore Wilson ◽  
Michael P. Hoffmann ◽  
Frank G. Zalom
Keyword(s):  
Maximum Temperature ◽  
Weather Station ◽  
Degree Days ◽  
Tomato Crop ◽  
Degree Day ◽  
Average Maximum ◽  
Temperature Ranges ◽  
The Mean ◽  
Weather Stations ◽  
Accumulated Degree Days

Temperatures recorded by weather stations and within the canopy of tomato (Lycopersicon esculentum Mill.) crops were compared in fields near Davis, Calif., during Summer 1983 (60 days) and 1987 (50 days). For both years, the average maximum and minimum temperatures, daily temperature ranges, degree days per day, and total accumulated degree days were compared. In 1983, the mean maximum temperature at the weather station did not differ significantly from that in the canopy, but the mean minimum temperature at the weather station was significantly lower than that in the canopy. In 1987, the mean maximum temperature at the weather station was significantly higher than that in the canopy, but mean minimum temperatures did not differ significantly. Temperature ranges were significantly narrower for the weather station toward the end of the 1983 season, and significantly wider for the weather station at midseason 1987. Comparisons of degree days per day showed significant differences between means at the weather station and in the canopy in 1983, and among those at the weather station and the two degree day calculation methods used for temperatures recorded in the canopy. Total accumulated degree days based on temperature records at the weather station were lower than those in the canopy in 1983 but higher in 1987. In 1987, the single sine degree day calculation method overestimated degree days compared to the 2-hr triangulation method. The phenology of the tomato crop as predicted by weather station temperatures indicated that tomato maturation was underestimated in 1983 and overestimated in 1987. The rate of development for hypothetical populations of Heliothis zea (Boddie) and Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) within the tomato crop was again underestimated in 1983 and overestimated in 1987, as based on temperature data of the weather station.

141 EFFECT OF ENVIRONMENTAL TEMPERATURE ON EMBRYO PRODUCTION AND CONCEPTION RATES IN BEEF AND DAIRY CATTLE

2009 ◽  
Vol 21 (1) ◽  
pp. 170
Author(s):  
Z. Hegedüsová ◽  
R. Holásek ◽  
M. Slezáková ◽  
A. Dufek ◽  
J. Kubica
Keyword(s):  
Dairy Cows ◽  
Embryo Quality ◽  
Environmental Temperature ◽  
Beef Cows ◽  
The Other ◽  
Effect Of Temperature ◽  
Frozen Embryos ◽  
Conception Rates ◽  
Temperature Ranges ◽  
The Mean

The aim of this study was to evaluate the effect of environmental temperature at the time of embryo collection and transfer on embryo quality and conception rates after transfer of fresh and frozen embryos. Purebred dairy (Holstein, Czech spotted cattle, n = 174) and beef (Charolais, Blonde d’Aquitaine, Piedmontese, Hereford, Limousin and Simmental; n = 72) donors were collected during 2005 to 2007. Donor cows received one application of PGF2α and superstimulation was initiated 9 to 11 days following estrus with pFSH (Folltropin-V; Bioniche Animal Health, Belleville, ON, Canada) given twice daily for 4 days. Prostaglandin2α was given on Day 3 of the superstimulation treatment. Donors were inseminated 3 times, with 1 unit of semen on Days 5 and 6 of treatment. Embryo recovery was carried out on Day 7 after insemination. The recipients were synchronized with PGF2α and embryos were transferred on Day 7 after estrus. The effect of temperature at the time of 246 embryo recoveries and 1338 transfers (fresh and frozen embryos) was analyzed using the GLM, assuming quasi-poisson and quasi-binomial error distribution by R software (www.r-project.org). We evaluated the total number of ova/embryos collected, embryo quality, and conception rates after transfer at the environmental temperatures shown below. Temperatures were divided into the following ranges: A) from –5 to 5°C; B) from 6 to 15°C; C) from 16 to 20°C; and D) over 20°C. The average temperature values were obtained from the Czech hydrometeorological institute and corresponded to the following seasons: winter (range A and B); spring (range B and C); summer (range C and D); fall (range C and B). Dairy cows were managed intensively in barns whereas beef cows were managed in barns during the winter and on pasture from April until October. In beef donors the mean number of total ova/embryos collected and transferable embryos were 9.1 ± 7.9 and 4.2 ± 4.5, respectively and no significant effect of temperature was detected (P > 0.05). In dairy donors the mean number of total ova/embryos collected and transferable embryos were 7.9 ± 6.0 and 4.9 ± 4.5, respectively and no significant effect of temperature was detected (P = 0.27). Conception rate was greatest (P < 0.001) in temperature range D (63.64%) compared with the other temperature ranges (A = 27.66%; B = 43.65%; C = 43.21%;) in beef cows and in the range C (65.31%) than in the other temperature ranges (A = 34.7%; B = 52.67%; D = 56.25%) in dairy cows. It was concluded that temperature at the time of embryo collection did not affect embryo production and quality. However, environmental temperature did have a significant effect on conception rates in both beef and dairy recipients. Nutritional status may also have contributed to the increased conception in beef cattle during warmer temperatures. However, the optimal period for conception in dairy cows was in temperature range from 16 to 20°C, because of the potential adverse effect of heat stress in high-yielding cows. Supported by MEYS CR MSM 2678846201, LA 330; NAZV 1B44034.

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