Max Temperatures Research Articles

Solar Driven Thermo-Electrochemical Hybrid Sulfur Process for Hydrogen Production

A hydrogen economy requires primary sources to provide the power required to produce hydrogen from water, fossil fuels, biomass or similar compounds. Water-splitting processes are particularly attractive, since water is abundant around the planet, the unique products from water splitting are hydrogen and oxygen and a variety of primary energy sources can be used to produce the hydrogen. External electric power can be used to produce hydrogen by conventional water electrolysis [1], but it firstly requires the production of electricity to realize the electrochemical splitting of the water molecule. A more efficient and potentially more cost effective approach is to use thermal power to drive a thermochemical water splitting process. Such cycles break the hydrogen-oxygen bounds through a series of heat-driven chemical reactions, with recirculation of intermediate substances of different type. By this approach the external heat which drives the chemical reactions is converted into chemical energy of the hydrogen produced from water splitting. Among the various water splitting processes, the thermo-electrochemical Hybrid Sulfur (HyS) is one of the most appealing cycles. It has only fluid reactants and is comprised of only two global reaction steps: a low temperature electrochemical exothermic section, operating at temperatures on the order of 100 °C, and a high temperature thermal section operating at max temperatures of about 800 °C. In the electrochemical section SO2 and H2O are combined together to produce electrochemically H2 at the electrolyzer cathode and H2SO4 at the electrolyzer anode. Sulfuric acid is recycled inside the plant, concentrated and decomposed, in the high temperature thermal section, into SO2, O2 and H2O. Oxygen is then separated from SO2 and water and extracted as byproduct of the process. Solar driven HyS process is being studied by the Greenway Energy and the University of South Carolina within the DOE HydroGEN program (part of the DOE Energy Material Network initiative) [2], partnering with the Idaho National Laboratory, the Savannah River National Laboratory and the National Renewable Energy Laboratory. The project mostly focuses on the high temperature sulfuric acid decomposition section, developing new optimized catalyst formulations (i.e. achieving higher conversion, lower performance lifetime degradation and lower costs), to be integrated in novel solar reactor systems. A new bimetallic catalyst formulation is being developed and synthesized, with the catalyst deposited on TiO2 support. Compared with the current state of the art sulfuric acid decomposition catalysts, developed by Idaho National Laboratory during the DOE Nuclear Hydrogen Initiative [3], the proposed catalyst shows the potential for higher SO3 conversion yields and very limited sintering effects. Test results, under sulfuric acid environment and operating temperatures on the order of 800 °C, will be shown and discussed. The new catalyst will be placed in a novel solar reactor, being developed within the HydroGEN project. The proposed concept is based on a solar cavity receiver system, realizing the sulfuric acid decomposition and internal heat recovery in a single unit, directly heated by the incident solar radiation. This system, along with the actual H2SO4 decomposition into SO2, allows: (1) efficient internal heat recovery from the decomposition products and (2) connections with the metallic interfaced HyS equipment (e.g. tubing, valves etc) at low temperatures. Preliminary results from detailed transport model analysis will be shown, demonstrating effective decomposition and internal heat recovery. The integration of the high temperature decomposition section with the low temperature electrochemical section of the HyS process has also been studied from a process modeling point of view. A new SO2 electrolysis concept is proposed and discussed, with a vapor SO2 mixture feeding the electrolyzer. Preliminary results show the potential to achieve high efficiencies, with actual voltage values lower than the traditional target of 600 mV and current densities higher than the target of 500 mA/cm2 [4]. A new process flowsheet, initially developed within the current HydroGEN project, will be presented and discussed, achieving thermochemical efficiencies ≥ 35%.

Numerical Modeling of a Novel Solar Driven Sulfuric Acid Decomposition Reactor

An efficient and cost-effective approach to produce hydrogen sees the direct use of thermal power to drive thermochemical water splitting processes. Such cycles break the hydrogen-oxygen bounds through a series of heat-driven chemical reactions, with recirculation of intermediate substances of different type. Among the various water splitting processes, the thermo-electrochemical Hybrid Sulfur (HyS) is one of the most appealing cycles. It has only fluid reactants and is comprised of only two global reaction steps: a low temperature electrochemical exothermic section, operating at temperatures on the order of 100 °C, and a high temperature endothermic thermal section operating at max temperatures of about 800 °C. In the electrochemical section SO2 and H2O are combined to produce electrochemically H2 at the electrolyzer cathode and H2SO4 at the electrolyzer anode. Sulfuric acid is recycled inside the plant, concentrated and decomposed, in the high temperature thermal section, into SO2, O2 and H2O. The endothermic decomposition of sulfuric acid takes place in two main reactions: H2SO4 → SO3 + H2O (1) SO3 → SO2 + 0.5 O2 (2) The required thermal power is provided by external source and by internal heat recovery from the SO2-O2 stream product of the decomposition reactions. Solar driven HyS process is being studied by the Greenway Energy and the University of South Carolina within the DOE HydroGEN program (part of the DOE Energy Material Network initiative) [1], partnering with the Idaho National Laboratory, the Savannah River National Laboratory and the National Renewable Energy Laboratory. The project focuses on the high temperature sulfuric acid decomposition section. One of the main tasks of the project is to develop and fabricate an effective and low cost high temperature solar reactor for the decomposition of the sulfuric acid into sulfur dioxide. Previous work was carried out within the DOE-NHI Initiative and resulted in identifying a reactor concept based on the bayonet heat exchanger as the baseline reactor configuration [2]. The bayonet reactor was tested both from a modeling point of view and from an experimental point of view, demonstrating the potential to achieve almost the reaction equilibrium conditions. At temperatures of about 800 °C and pressures of 14 bar, an SO2 production of approximately 19 mol fraction % was achieved, which is essentially the equilibrium value at the same operating conditions [3,2]. However, a solar driven bayonet concept presents several drawbacks, mainly relative to the need for an additional intermediate heat exchanger to transfer the solar power to the reactive sulfur mixture. The removal of the intermediate solar heat exchanger will result in increased energetic and exergetic efficiencies and decreased capital and operating costs. A novel reactor concept is proposed, described and discussed, based on a direct solar heated cavity receiver system. It realizes the solar driven sulfuric acid decomposition and internal heat recovery in a single unit, directly heated by the incident solar radiation without the presence of any intermediate heat transfer fluid. The reactor includes catalytic structures to decompose H2SO4 and foamed structures in the internal heat recovery channels to increase the overall thermal conductivity. A reactor unit, made of SiC material, and directly heated from solar radiation has preliminarily been demonstrated from a modeling point of view. A detailed transport phenomena model was developed using Finite-Volume approach and run in STAR-CCM+. The kinetics parameters reported in Reference [3] were adopted for the current simulations. Results showed excellent conversion rates and reduced temperature gradients and pressure drops inside the device, achieving better performance than the bayonet configuration. The cavity receiver-reactor also allows: (1) efficient internal heat recovery from the decomposition products and (2) connections with the metallic interfaced HyS equipment (e.g. tubing, valves, etc.) at low temperatures. Results obtained from a first conceptual scale up analysis of the reactor concept also demonstrated the actual feasibility for integration in both centralized and distributed solar tower based plants.

Functional Analysis of Air Temperatures as Related to Chilling Requirements of Perennial Fruit Crops

After more than two centuries of observation and research on chilling requirements of perennial fruit crops, there remain unresolved aspects concerning relationships between chilling condition and ambient air temperatures. The purpose of this ongoing study was to further explain association between chilling temperature and plant functions: growing, chilling, and freezing. Temperature data consisted of 5-year averages for 50 Mesonet weather sites randomly located throughout Kentucky. Based upon the Chilling Hours Model analysis, available chilling hours exceeded requirements of commonly grown perennial fruit crops. In the extended study, max and min daily temperatures were processed separately permitting their comparisons within plant functional classes. Nearly twice as many min as max temperature days were included within the chilling class function. Most consecutive days of chilling temperatures ranged from 1 to 3 days and were more clustered with min than max temperatures. Using multiple-year averages especially when the temperatures were near freezing point, resulted in a high percentage of individual years with freezing temperatures that were not reflected in the group average. Separating max and min temperatures in functional classes permitted greater focus on critical temperature-chilling relations. Within the chilling range, impact of min on chilling was nearly twice that of max. Contrariwise, widely reported research literature confirms that global warming has greater influence on min than on max or mean temperatures.

Physical Activity of Patients with COPD from Regions with Different Climatic Variations

ABSTRACTSeasonal changes in physical activity in daily life (PADL) of patients with Chronic Obstructive Pulmonary Disease (COPD) living in regions of the world with contrasting (i.e., mild or marked) weather variations have not been yet investigated. We aimed to quantify PADL and compare its variability caused by seasonality in patients with COPD who live in world regions with different summer-winter climatic variations (i.e. Londrina, Brazil and Leuven, Belgium). In a longitudinal, prospective and observational study, patients with COPD from Brazil and Belgium wore the SenseWear Armband for 7 days in summer and 7 days in winter. Active time (≥2METs) was the primary outcome. PADL data were matched day-by-day with weather information. Regarding the two assessment moments, median (min;max) temperatures were 11 (−5.5;27.2)°C in Leuven and 21 (7;27)°C in Londrina. Patients in Brazil (n = 19, 69 ± 7 years, FEV1 47 ± 15%pred) and Belgium (n = 18, 69 ± 6 years, FEV1 50 ± 15%pred) decreased their active time in winter compared to summer (p < 0.05), and this reduction was more pronounced in Brazil (p = 0.01, between group). Mean, minimum and maximum temperature, daylight duration and relative humidity were significantly related to active time. Patients with COPD decrease their PADL in winter even in a region with milder climatic variation.

Simulation of leaf blast infection in tropical rice agro-ecology under climate change scenario

Assessing disease risk has become an important component in the development of climate change adaptation strategies. Here, the infection ability of leaf blast (Magnaporthe oryzae) was modeled based on the epidemiological parameters of minimum (T min), optimum (T opt), and maximum (T max) temperatures for sporulation and lesion development. An infection ability response curve was used to assess the impact of rising temperature on the disease. The simulated spatial pattern of the infection ability index (IAI) corresponded with observed leaf blast occurrence in Indo-Gangetic plains (IGP). The IAI for leaf blast is projected to increase during the winter season (December–March) in 2020 (2010–2039) and 2050 (2040–2069) climate scenarios due to temperature rise, particularly in lower latitudes. However, during monsoon season (July–October), the IAI is projected to remain unchanged or even reduce across the IGP. The results show that the response curve may be successfully used to assess the impact of climate change on leaf blast in rice. The model could be further extended with a crop model to assess yield loss.

Assessment and Mapping of Urban Heat Island using Field Data in the New Capital Region of Andhra Pradesh, India

Objectives: To assess and map Urban Heat Island (UHI) and its intensity using field-based measurement of Land Surface Temperature (LST) in the newly formed capital region of Andhra Pradesh. Methods/Statistical Analysis: UHI development is one of the several consequences of urban sprawl and land use changes causing several environmental impacts on the urban dwellers. Assessment through field-based measurement of LST provides an instant and accurate insight into the extent and intensity of UHI. New capital region of Andhra Pradesh is having a lot of potential for urban sprawl because of the developmental activities proposed and hence taken as the case study. Using Infrared thermometer, LST was measured at 212 locations in the capital region, and corresponding locations were identified using latitudes and longitudes obtained from a hand-held GPS. LST measurements were made between 11 a.m. to 02 p.m. during the month of May, 2016. The latitude, longitude and LST data were used to develop map showing the UHI phenomenon using Arc GIS. Inverse Distance Weighted method, an interpolation algorithm available with spatial analyst module of Arc GIS, is used to develop a map showing the spatial variation of LST. Findings: From the output, it is clearly understood that UHI occurs mainly in the Vijayawada and Guntur cities. The max and min temperatures of LST measured in the study area are 50.49oC and 25.43oC respectively. UHI spreads to about 16708 hectares in Vijayawada and 25057 hectares in Guntur. Applications/Improvements: Field measured data-based analysis gives an accurate picture of the UHI in the study area. It was also found that low temperatures were recorded in areas with dense vegetation. Urban greening is the only method to reduce the UHI phenomenon and to mitigate the impacts.

Spatial and Temporal Variation in Dust Deposition Rate in Isfahan and its Relationship with Selected Climatic Parameters

Spatial and temporal distribution of dust deposition rate (DDR) in Isfahan city and the influencing climatic parameters were studied. Dust samples were collected using glass trays placed on the roof of one-story buildings from 20 sites in Isfahan city for 12 months. Climatic data were obtained from Meteorological Organization and analyzed. The highest and the lowest amount of DDR in agreement with the direction of prevailing wind were observed for dry months with eastern and northeastern wind directions and wet periods with western and southwestern wind directions, respectively. This can indicate dust emission from the desert located in eastern part of Isfahan city. Statistically significant inverse correlation between DDR and precipitation and relative humidity, and significant and positive correlation of DDR with Min and Max temperatures in all the studied months and also with Max and average wind speed for dry sampling months may well justify the temporal distribution of DDR in the city. In dry months, finer particles from eastern desert can be transported a longer distance and deposited in the western part of the city, far from the source area. In wet seasons, however, soil aggregates become coarser as a result of particle adhesion. This, in turn, results in the deposition of dust near the source area as the transporting power of dust reduces.

Plasticity of the thermal requirements of exotherms and adaptation to environmental conditions.

In exothermal organisms, temperature is an important determinant of the rate of ecophysiological processes, which monotonically increase between the minimum (td min) and maximum (td max) temperatures typical for each species. In insects, td min and td max are correlated and there is a approximately 20°C interval (thermal window WT = td max − td min) between them over which insects can develop. We assumed that other exotherms have similar thermal windows because the thermal kinetics of their physiological processes are similar. In this study, we determined the thermal requirements for germination in plants. Seeds of 125 species of Central European wild herbaceous and crop plants were germinated at nine constant temperatures between 5 and 37°C, and the time to germination of 50% of the seeds D and rate of germination R (=1/D) were determined for each temperature and the Lactin model used to determine td min, td max, and WT. The average width of the thermal windows for seeds was significantly wider (mean 24°C, 95% CI 22.7–24.2°C), varied more (between 14.5 and 37.5°C) and development occurred at lower temperatures than recorded for insects. The limiting temperatures for germination, td min and td max, were not coupled, so the width of the thermal window increased with both a decrease in td min and/or increase in td max. Variation in WT was not associated with taxonomic affiliation, adult longevity, or domestication of the different species, but tends to vary with seed size. Plants are poor at regulating their temperature and cannot move to a more suitable location and as a consequence have to cope with wider ranges in temperatures than insects and possibly do this by having wider thermal windows. Synthesis: The study indicated specificity of WT in different exotherm taxa and/or their development stages.

Approach of a solar building integrated with multiple novel solar technologies

A novel solar building is constructed in Hefei, China. The solar energy can supply the building with solar power, solar space heating, solar-cooling and solar-hot water by corresponding novel solar technologies and components. Preliminary simulation by TRNSYS showed that the solar building could reduce >30% of the energy consumption compared with the same scale of the office building in Hefei during the heating season. In an experiment performed on 20 February 2013, the max temperatures of both the north room and south room reached 21°C and the average temperatures were 17°C, only using the solar air heating system.

Recent (1980–2009) evidence of climate change in the upper Karakoram, Pakistan

We investigate here recent (1980–2009) climate variability in the upper Karakoram, Northern Pakistan, of particular interest given the peculiar glacier behavior during the last two decades. Differently from other glacierized regions in the Hindu Kush–Karakoram–Himalaya region, glaciers in the Karakoram display limited ice thinning, and in some cases advancing has been detected. Climate analysis is required to describe recent (i.e., last three decades) variability, to aid highlighting of the factors driving glacier evolution. Starting from monthly data, we analyze seasonal values of total precipitation, number of wet days, maximum (max) and minimum (min) air temperature, max precipitation in 24 h, and cloud cover for 17 weather stations in the upper Karakoram, clustered within three climatic regions as per use of principal components analysis. We detect possible nonstationarity in each of these regions by way of (1) linear regression, (2) moving window average, and (3) Mann–Kendall test, also in progressive form, to detect the onset date of possible trends. We then evaluate linear correlation coefficients between Northern Atlantic Oscillation (NAO) index and climate variables to assess effectiveness of teleconnections, claimed recently to affect climate in this area. Also, we compare temperature within the investigated zone against global temperature anomalies, to evidence enhanced warming within this area. We found mostly nonsignificant changes of total precipitation, unless for few stations displaying increase in Chitral-Hindu Kush region and Northwest Karakoram, or Gilgit area, and decrease in Western Himalaya, Kotli region. Max precipitation is mostly unchanged, unless for slight increase in Chitral and Gilgit areas, and slight decrease in Kotli region. Number of wet days is mostly increasing in Gilgit area, and decreasing in Chitral area, with no clear signal in Kotli region. Min temperatures increase always but during Summer, when decreasing values are detected, especially for Gilgit and Chitral regions. Max temperatures are found to increase everywhere. Cloud cover is significantly increasing in Gilgit area, but decreasing otherwise, especially in Kotli region. Max temperature regime is significantly positively correlated against global thermal anomaly, while min temperature regime is nonsignificantly negatively correlated. Max and min temperatures seem mostly negatively correlated to NAO. Some dependence of trend intensity for the considered variables against altitude is found, different for each region, suggesting that investigation of weather variables at the highest altitudes is warranted to discriminate further climate variability in the area.

Thermal Tolerance of Antarctic Notothenioid Fishes Correlates with Level of Circulating Hemoglobin

The West Antarctic Peninsula region is experiencing some of the most rapid elevations in temperature of any marine environment. We assessed thermal tolerance of white- and red-blooded Antarctic notothenioid fishes inhabiting these waters, using a modified critical thermal maximum (CT(max)) design. Temperature was elevated acutely from ambient at a constant rate of 3.6°C h(-1), and CT(max) was defined as the temperature where animals lost righting response. CT(max) temperatures of white-blooded icefishes Chionodraco rastrospinosus (13.3° ± 0.2°C) and Chaenocephalus aceratus (13.9° ± 0.4°C) were significantly lower than those of red-blooded fishes Gobionotothen gibberifrons (15.5° ± 0.2°C) and Notothenia coriiceps (17.1° ± 0.2°C). Lepidonotothen squamifrons, a red-blooded species with low hematocrit, exhibited a CT(max) (14.2° ± 0.4°C) that was significantly lower than that of the other red-blooded animals and similar to that of icefishes. A strong relationship between CT(max) and hematocrit (r(2) = 0.76) suggests that the oxygen-carrying capacity of blood may partially dictate acute lethal temperature. Despite a short treatment duration, we detected a rise in the mRNA level of hypoxia response gene HIF-1α in N. coriiceps heart tissue. One-week exposure to 4°C had no effect on the CT(max) of N. coriiceps, indicating an inability to compensate for rising temperature under these experimental conditions. Our results suggest that icefishes are particularly sensitive to temperature elevation because of a lack of hemoglobin and may be a sentinel taxon for climate change.

PredictingLeptodactylus(Amphibia, Anura, Leptodactylidae) Distributions: Broad-Ranging Versus Patchily Distributed Species Using a Presence-Only Environmental Niche Modeling Technique

Locality data available for many, if not most, species of Neotropical frogs are based on written descriptions of the collecting sites, not on GPS device determined coordinate data. The pre-GPS device data are imprecise relative to GPS data. Niche modeling is a powerful technique for predicting geographic distributions that provides the best results when the locality data are precise. The purpose of this study is to determine whether imprecise historical locality data are sufficient such that niche modeling techniques can yield realistic new insights to species-level distributions. Two sets of frogs of the genus Leptodactylus that have known different kinds of distributions are evaluated: two species with broad, presumably continuous distributions, and four species known to occur in patchy, disjunct habitats in South America. BIOCLIM, a presence-only environmental niche modeling algorithm,was used to define suitable occupancy areas based on multiple sets of environmental parameters that include: monthly mean, max, and min temperatures, and monthly precipitation. A Nature Conservancy — Natureserve ecoregion layer and a high resolution elevation layer were also included in the analyses. Our analyses yield new realistic insights and questions regarding distributions of the Leptodactylus species we evaluated. We recommend incorporation of the Nature Conservancy — Natureserve layer to evaluate Neotropical distributions, as the layer gave much more robust results than use of only the climatic variable analyses.

Effect of binder content on relative density, microstructure and properties of complex cemented carbides obtained by thermal explosion-pressing

Combustion in thermal explosion mode of the mixtures (Ti–Cr–Mo–W-graphite) under low uniaxial pressure of 19 MPa was used to produce cemented carbides (complex carbides/iron–nickel alloy). The results of the investigations showed that ignition ( T ign) and combustion ( T max) temperatures, as well as material density, structure and properties, were sensitive to the iron–nickel additions. When the iron–nickel content increases, combustion is characterized by a lowering from T ign and a reduction in reactions heating effect. The carbide formation was carried out by selective mechanism. Carbides of titanium (TiC) and chromium (Cr 23C 6) were formed instantaneously during the exothermic peak. However, the molybdenum carbide (Mo 2C) and mainly the tungsten carbide (W 2C) resulted from incomplete carbon diffusion in solid state. An isothermal maintenance under pressure at 1373 K, has allowed to accelerate the material densification mechanisms by viscous flow. At the same time, it completed the carbides formation thanks to the carbon diffusion mechanism as shown by the presence of new phases such as WC and Cr 7C 3. The maximum effect of densification was observed for a binder content of 50 wt.%, where the relative density of product attained 95%. The Vickers hardness (HV 0.15) depends also on the binder content and varies from 6300 MPa to 19,000 MPa. The best tribological behaviour was achieved on cermets with 30% (Fe–Ni).

Temperature and relative humidity distributions in a medium-size administrative town in southwest Nigeria

This study was carried out in one of the medium-sized public administrative towns in the southwestern part of Nigeria. Its aim is to highlight the effect of spatial distribution of settlements, population, and socio-economic activities on urban air temperature and humidity in the town. Temperature and relative humidity data from 1992 to 2001 were obtained from three meteorological stations in Akure, the Administrative Capital of Ondo State, Nigeria. The stations are located within the Federal Ministry of Aviation, Akure Airport (FMA), Federal University of Technology, Akure (FUTA) and Federal School of Agriculture (SOA). Air temperature and relative humidity measurements were also obtained from 27 points, which were cited to include road junctions, markets, built up areas, etc., using sling psychrometer. The data were subsequently analysed for spatial and temporal variations using statistical packages (SPSS and Microsoft Excel) and isolines. Actual vapour pressure and dew point temperature were computed using Magnus conversion formulae. The results obtained showed that spatial variation was insignificant, in terms of the temperature and humidity variables. The annual mean temperature ( T mean) ranged between 21.9 and 30.4 °C while minimum ( T min) and maximum ( T max) temperatures varied from 13 to 26 and 21.5–39.6 °C, respectively. Relative humidity (RH), actual vapour pressure ( E s) and dew point temperature ( T d) values also varied from 39.1% to 98.2%, 19.7–20.8 g m −3, and 17.3–17.8 °C, respectively. A significant relationship ( p>0.6; r<0.05) between T min, E s and T d was observed while the daytime ‘urban heat island’ intensity (UHI) ranged between 0.5 and 2.5 °C within the study period. The study concluded that there is influence of urban canopy on the microclimate of Akure, and hypothesizes that the urban dwellers may be subjected to some levels of weather related physiological disorderliness.

Screening Capsicum species of different origins for high temperature tolerance by in vitro pollen germination and pollen tube length

Successful fruit set depends on several reproductive processes including pollen germination and tube growth processes. An experiment was conducted to determine the effects of temperature on pollen germination characteristics and to identify species/genotypic differences in Capsicum using the cumulative temperature response index (CTRI) concept. Pollen was collected from plants of seven genotypes from five Capsicum species, adapted to various parts of the world and grown outdoors in large pots. The pollen was subjected to in vitro temperatures ranging from 15 to 50 °C at 5 °C intervals. Pollen germination and tube lengths were recorded for all species after 24 h of incubation at the respective treatments. Species/genotypes differed significantly for in vitro pollen germination percentage and pollen tube length with mean values of 78% and 734 μm, respectively. The mean cardinal temperatures ( T min , T opt , and T max ) averaged over genotypes, were 15.2, 30.7, and 41.8 °C for pollen germination and 12.2, 31.2, and 40.4 °C for pollen tube growth. The CTRI of each species/genotype calculated as the sum of eight relative individual stress response values, such as maximum pollen germination, maximum pollen tube length; T min , T opt , and T max temperatures of pollen germination, and pollen tube lengths, identified species tolerance to high temperatures. Capsicum annum cv. Mex Serrano from Mexico was identified as tolerant, C. chacoense cv. 1312 and C. spp. cv. Cobanero from Argentina and Guatemala, respectively as intermediate and C. frutescens cv. Early Spring Giant from China, C. annum cv. Long Green from South Korea , C. spp. cv. NM89C130 and C. pubescens cv. 90002 from Guatemala as sensitive to high temperatures. The tolerant species/genotypes can be used in breeding programs to develop new genotypes that can withstand high temperature conditions both in the present climate and particularly in a future warmer climate.

Root Zone Temperatures of Viburnum odoratissimum Grown in the Multipot Box System and Conventional Systems: Measurement and Analyses of Temperature Profiles and Predicting Root Zone Temperatures

This research study evaluates the effectiveness of a recently introduced irrigation-plant production system, multipot box system (MPBS), for moderating root zone temperature (RZT) compared with the conventional nursery containers. The study also deals with the development, calibration, and validation of a series of models that can be used to predict maximum (max) and minimum (min) RZTs using commonly available input variables. The Viburnum odoratissimum (Ker.-gawl.) was used as the test plant. Models were calibrated in the fall growing season and validated during the summer. The RZT was used as the dependent variable while the max and min air temperatures (Tmax and Tmin) and/or incoming solar radiation (Rs) were used as independent variables. The color of the MPBS had an effect on plant growth. Plants grown in the white MPBS had higher growth indices, shoot and root dry weights, and number of stems as compared with the plants in the black MPBS or the conventional (control) system (CS). White MPBS maintained cooler RZTs than the max air temperature during both seasons. Also, white MPBS maintained cooler RZTs than the black MPBS and CS during the two seasons. In both seasons, water temperature in the black MPBS was higher than the temperature in the white MPBS contributing to the high RZTs in the black MPBS. The RZT of the black MPBS and CS exceeded the critical value (40 °C), which is cited in the literatures as negatively impacting root growth, water and nutrient uptake, leaf area, plant survival, root and shoot dry weights, water status, and photosynthesis. The RZT in the CS was above 45 °C for most of the summer season and plants were exposed to this extreme temperature for a few hours a day during most of the summer. The white MPBS provided a better environment and enhanced plant growth. For regions where ambient air temperature ranged from 2 to 41 °C, the white MPBS can provide adequate and effective RZT protection for plants grown in No. 1, 3.8-L standard black conventional containers. Predicted RZT values were well correlated with measured values in all systems. Rs did not have an effect on predicting RZTmax in the MPBS treatments. Wind speed did not contribute to predicting RZT in any production systems. The root mean square error between measured and predicted RZT was relatively low ranging from 0.9 to 2.8 °C. Models were able to explain at least 74% of the variability in RZTs using only Tmax, Tmin, and/or Rs. Models developed in this study should be applicable for estimating RZTs when similar management and cultural practices are present. Models of this study are practical, simple, and applicable to predict RZTs where ambient air temperature ranges from 1.9 to 40 °C. Model results should not be extrapolated beyond these limits.

Using natural maturation series to evaluate the utility of parallel reaction kinetics models: an investigation of Toarcian shales and Carboniferous coals, Germany

Open-system pyrolysis is routinely performed on immature samples in order to determine the kinetic parameters of petroleum generation at both bulk and molecular levels. This study tested such predictions for Type II and Type III organic matter by making calibrations with both artificial and natural maturity sequences of Toarcian shales (Posidonia shale; 0.48–1.44% R r) and Carboniferous vitrains (0.74–2.81% R r). Both natural series showed little or no compositional variability attributable to kerogen type. Artificially matured samples were prepared by non-isothermal heating (0.7 K/min) of the least mature samples up to end temperatures between 375 and 470°C under either closed- or open-system conditions. Measured generation rate versus temperature curves were analyzed assuming a distributed system of activation energies and a single frequency factor in each case. The resulting kinetic parameters were then used to assess bulk petroleum formation rates for geological heating conditions. In the case of all artificially matured samples, measured and predicted bulk petroleum formation rate vs. temperature curves for each maturation stage remain within the original envelope defined by the least mature sample, despite an upward shift of T max temperatures. This confirms that the reactions taking place during both the pyrolysis measurements and simulated maturation processes are the same, involving mainly homolytic cracking. A similar pattern of measured and predicted rate curves is reproduced by the natural maturation sequence of the Toarcian shales in the maturity range of 0.53 to 1.44% R r suggesting that petroleum generation within these natural systems also results from cracking reactions, and therefore that petroleum generation over geological time can be reliably extrapolated from open-system pyrolysis of the appropriate immature sample. By contrast, significant deviations are observed for the natural coal series, with measured and predicted rate curves extending beyond the immature envelopes. In accordance with the pronounced increase of frequency factors and of protonated aromatic carbon concentrations, this behavior is attributed to solid state aromatization reactions which compete with product generation during natural coalification, but which are not reproducible to the same extent by experimental heating. It is concluded that petroleum generation from vitrinitic coals over geological time cannot be reliably extrapolated from open-system pyrolysis of low rank samples.

Determining Heat Unit Requirements for Broccoli Harvest in Coastal South Carolina

The objective of this research was to determine the least variable method to predict the dates of the first and last broccoli (Brassica oleracea L. var Italica) harvests based on heat unit summation using coefficients of variation (cv). The method with the lowest cv for predicting first harvest was to sum, over days from planting to harvest, the difference between the growing season mean (GSM) temperature and a base temperature of 7.2 °C. If the GSM maximum (max) temperature, however, was &gt;26.7 °C, an adjusted max temperature was calculated by first subtracting 26.7 °C from the GSM max temperature and then subtracting the GSM mean temperature. Then the growing degree days (GDDs) were summed by subtracting the base temperature of 7.2 °C from the average of the GSM minimum (min) and adjusted max temperatures. This method produced a cv of 3.96 compared to 4.13 for the standard method of summing over the entire growing season, the mean temperature minus the base temperature of 4.4 °C. The method with the lowest cv for predicting last harvest was to sum, over days from planting to harvest, the difference between the GSM max temperature and a base temperature of 7.2 °C. If the GSM max temperature, however, was &gt;29.4 °C, the base temperature was subtracted from 29.4 °C and not the actual GSM max temperature. This method produced a cv of 3.71 compared to 4.10 for the standard method of summing over the growing season, the mean temperature minus the base of 4.4 °C.

Dynamic Relationships between Field Temperatures and Broccoli Head Quality

Fifty-six field plantings of `Baccus', `Citation', `Packman', and `Southern Comet' broccoli were made in Charleston, S.C., at 2-week intervals from February to November from 1990 to 1992. The objective was to determine broccoli's response to growing season mean (GSM) temperatures for several important market quality characteristics, such as head shape, color, density, leafiness, and bead size. Regression analysis determined whether quality was more affected by GSM minimum (min) or maximum (max) temperature for each head quality characteristic. Head leafiness and density of `Baccus' were insensitive to GSM min (7.0 to 23.5 °C) and GSM max (17.5 to 32.5 °C) temperatures experienced during these years. `Baccus' head color was unacceptable at &lt;20.3 °C GSM max and head shape was unacceptable at &lt;19.8 and &gt;26.8 °C GSM max. `Citation' head color and leafiness were unacceptable at &gt;20.5 and &gt;20.2 °C GSM max, respectively. Head density of `Citation' was unacceptable at &lt;19.2 and &gt;28.9 °C GSM max and head shape was unacceptable at &lt;18.4 and &gt;25.7 °C GSM max. Quality of `Packman' was unacceptable for head color at &lt;21.0 and &gt;27.3 °C GSM max, head leafiness at &gt;32.0 °C GSM max, head density at &lt;8.4 and &gt;18.0 °C GSM min, and head shape at &gt;22.0 °C GSM max. `Southern Comet' head quality was unacceptable for head color at &lt;9.2 and &gt;16.5 °C GSM min, head leafiness at &gt;32.0 °C GSM max, head density at &lt;8.9 and &gt;16.2 °C GSM min, and head shape at &lt;21.0 and &gt;25.3 °C GSM max. GSM min or max temperatures did not affect bead size of any cultivar during any planting time studied.

Pheromone Monitoring of Peachtree Borers and Lesser Peachtree Borers in South Carolina12

The peachtree borer, Synanthedon exitiosa (Say). and lesser peachtree borer, Synanthedon pictipes (Grote and Robinson), were monitored with pheromone-baited traps in 2 peach-growing areas. Pheromone monitoring was compared to cast skin counts in one orchard. Similar seasonal distributions were obtained by using both methods, though the pheromone traps were more sensitive in detecting sparse populations. Trap catch data were compared to precipitation patterns. Physiological days at 27°C between the medians of generations were calculated by using daily max and min temperatures. Calculations of physiological days were in agreement with developmental times as determined in laboratory rearing. Wet periods were found to enhance the eclosion of both species.