Steady Increase In Temperature Research Articles

Bacterial reduction and temperature increase of titanium dental implant models treated with a 445 nm diode laser: an in vitro study

In this in vitro study, the use of a 445 nm diode laser was investigated for the decontamination of titanium dental implants. Different irradiation protocols and the effect of repetitive laser irradiation on temperature increase and decontamination efficacy were evaluated on titanium implant models. An automated setup was developed to realize a scanning procedure for a full surface irradiation to recapitulate a clinical treatment. Three irradiation parameter sets A (continuous wave, power 0.8 W, duty cycle (DC) 100%, and 5 s), B (pulsed mode, DC 50%, power 1.0 W, and 10 s), and C (pulsed mode, DC 10%, power 3.0 W, and 20 s) were used to treat the rods for up to ten consecutive scans. The resulting temperature increase was measured by a thermal imaging camera and the decontamination efficacy of the procedures was evaluated against Escherichia coli and Staphylococcus aureus, and correlated with the applied laser fluence. An implant’s temperature increase of 10 °C was set as the limit accepted in literature to avoid thermal damage to the surrounding tissue in vivo. Repeated irradiation of the specimens resulted in a steady increase in temperature. Parameter sets A and B caused a temperature increase of 11.27 ± 0.81 °C and 9.90 ± 0.37 °C after five consecutive laser scans, respectively, while parameter set C resulted in a temperature increase of only 8.20 ± 0.53 °C after ten surface scans. The microbiological study showed that all irradiation parameter sets achieved a complete bacterial reduction (99.9999% or 6-log10) after ten consecutive scans, however only parameter set C did not exceed the temperature threshold. A 445 nm diode laser can be used to decontaminate dental titanium rods, and repeated laser irradiation of the contaminated areas increases the antimicrobial effect of the treatment; however, the correct choice of parameters is needed to provide adequate laser fluence while preventing an implant’s temperature increase that could cause damage to the surrounding tissue.

Behavioral strategy of adaptation of <i>Polypterus senegalus</i>(Polypteridae) with an increase in ambient temperature

This paper investigates the effect of temperature increase on the behaviour of Polypterus under laboratory experimental conditions. To investigate the effect of a change in temperature regime, analysis of video recordings of animal behaviour over eight hours under acclimation conditions and under a constant temperature increase is used. The temperature increase occurred at a rate of 1,125°C/hour. The movement trajectories of the animals under normal conditions and under a sudden increase in ambient temperature are described. The paper presents results on the speed and activity of the fish movements and the number of acts of air entrapment by polypterus from the water surface. The studies show that the increase in temperature leads to an increase in the variability of the animals’ movement trajectories. A steady increase in temperature leads to an increase in the speed and activity of the animals’ movements. As the temperature regime changes, there is an increase in the number of acts of air capture from the water surface. The largest jump in activity change is observed in the second and third hours of temperature increase. The obtained material can serve as a basis for the development of ideas about the behavioural adaptation of bony fishes to the increase in ambient temperature. The observed regularities in the responses to temperature changes will make it possible to improve the technology of polypterus cultivation.

A Ten-Year Record Shows Warming Inside the Belize Barrier Reef Lagoon

The Belize Barrier Reef system (BBR) in the western Caribbean’s Gulf of Honduras contains a large region of lagoon coral reef, seagrass and mangrove habitat. As the largest lagoon habitat within the Caribbean, this region experiences differing oceanographic and temperature conditions as compared to deeper offshore areas. The occurrence of several endemic species within the Gulf of Honduras area and inside the Belize lagoon supports the hypothesis that this area is a unique biogeographic region. Consequently, the ecological effects of temperature increase due to global climate change may have a long-term adverse impact on this region’s unique marine species. This study reports an in situ temperature record over a ten-year period (2004–2014) collected from a coral reef offshore of Wee Wee Cay within the South Water Cay Marine Reserve of Belize. There was a steady increase in temperature during the decade.

Heat tolerance in Drosophila melanogaster is influenced by oxygen conditions and mutations in cell size control pathways.

Understanding metabolic performance limitations is key to explaining the past, present and future of life. We investigated whether heat tolerance in actively flying Drosophila melanogaster is modified by individual differences in cell size and the amount of oxygen in the environment. We used two mutants with loss-of-function mutations in cell size control associated with the target of rapamycin (TOR)/insulin pathways, showing reduced (mutant rictorΔ2) or increased (mutant Mnt1) cell size in different body tissues compared to controls. Flies were exposed to a steady increase in temperature under normoxia and hypoxia until they collapsed. The upper critical temperature decreased in response to each mutation type as well as under hypoxia. Females, which have larger cells than males, had lower heat tolerance than males. Altogether, mutations in cell cycle control pathways, differences in cell size and differences in oxygen availability affected heat tolerance, but existing theories on the roles of cell size and tissue oxygenation in metabolic performance can only partially explain our results. A better understanding of how the cellular composition of the body affects metabolism may depend on the development of research models that help separate various interfering physiological parameters from the exclusive influence of cell size. This article is part of the theme issue 'The evolutionary significance of variation in metabolic rates'.

Recent increase in autumn temperature has stabilized tree growth in forests near the tree lines in Chilean Patagonia

AbstractIt is widely accepted that global warming is affecting forests near the tree line by increasing tree growth in these cold‐limited environments. However, since about 1970, a reduction in tree growth near the tree line has been observed in response to warming and increased drought stress. This reduction in tree growth has been mainly reported in forests of the northern hemisphere but less studied in southern forests. In this study, we investigated tree populations of Nothofagus pumilio located near the arboreal altitudinal limit in the central Patagonian Andes (45–47° S, Aysén region, Chile). In this region, warming has been accompanied by increased drought conditions since the 2000s. We explored whether this climatic variability has promoted or reduced tree growth at the regional scale in tree lines of these broadleaved temperate forests of central Patagonia. We constructed tree‐ring chronologies and determined common growth patterns and trends, and then analyzed the influence of recent climate. We detected a significant change in the slope of regional growth trends between the periods 1955–1985 and 1985–2015. We found that positive growth trends in the period 1955–1985 were associated with warmer and drier springs. However, after 1985, we found a stabilization in N. pumilio growth associated with a steady increase in temperature in autumn. Our results support the idea that more frequent warm autumns, with very thin or no snow cover, have stabilized tree growth due to water deficit at the end of the growing season of N. pumilio. The predicted climate change scenario of increasing temperatures and drought in central Patagonia may increase competition among trees for water, particularly at the end of the growing season. Consequently, we could expect a decreasing forest growth trend in central Patagonia, potentially impacting forest dynamics of these southern forests.

Effects of loss of heat sink transient on flow characteristics in a closed natural circulation system

Flow characteristics during loss of coolant to the heat exchanger (HX) via the secondary loop cold leg of a natural circulation (NC) test facility referred here as loss of heat sink transient (LOHS) in a closed rectangular NC system having a single heated channel at two different heating powers and system pressures has been investigated experimentally. Two LOHS experiments (LOHS-1 and LOHS-2) were conducted in a well dimensioned closed loop NC test facility designed to represent the primary system of a nuclear reactor. Operating conditions were set and maintained at 6.0 kW and 9.0 kW with system pressures of 0.2 MPa and 0.5 MPa respectively for both single-phase and single-to-two-phase flow transition to determine their thermal hydraulic responses at these predetermined parameters. The transients were initiated by closing the cold leg of the secondary loop supplying coolant to the tube-in-shell heat exchanger while NC flow phenomena were monitored at each vital section along the flow map based on the pre-determined inlet operating conditions. LOHS experiment stops when critical heat flux (CHF) occurs or heat exchanger outlet (HXoutlet) temperature rises too high to approximately equal its inlet temperature. Results were acquired using a system-design platform and development environment LabVIEW, programmed in a dedicated computer that was interfaced with the coupled sensors in the measuring devices. Common computational tools which include MATLAB, Ms Excel and Origin software were used for the analysis of the acquired data. Results at the inlet and outlet of heated sections as well as the inlet and outlet of condensers of both tests were analyzed and discussed in details at various flow regimes with the associated phenomena. It is concluded that while stable flow was maintained before transient with slug flow occurring in the heating channel, the system experienced transient stability resulting in steady temperature increase and subsequently drops into an instability region when the transient scenario was activated. In addition, the NC system transited into stable two-phase flow and further loses stability when HXoutlet temperature surges to its inlet value with CHF occurrence. These results are presented to contribute to a more extensive utilization of NC systems and understanding of flow behavior during LOHS in advanced reactors.

Impact of climate change on water resources and agricultural production

The article highlights the research results on the assessment of natural moisture supply in Ukraine, the state of water resources and agricultural production in the face of modern climate change taking into account the forecast for the medium and long term prospects. It was established that the rate of air temperature growth for the period of 1975-2019 in Ukraine ranges from 0.61 to 0.82oC, while in neighboring post-Soviet countries (Russia, Moldova, Belarus) – this figure is 0.47 - 0.59oC, and in the northern hemisphere and Europe – it is 0.34 and 0.47oC respectively. These data show that the rate of air temperature rise in Ukraine is much higher compared to European countries and the whole world. The rapid rise in average annual temperature in Ukraine is not accompanied by a significant increase in precipitation. Its amount in Ukraine as well as in some other regions remains virtually unchanged. Due to the steady increase in temperature, the area of ​​Ukraine with a significant deficit of natural moisture supply for the period of 1990-2015 increased by 7%, and with excessive and sufficient natural moisture supply, on the contrary, decreased by 10%. If the current warming rates are kept until 2050 and 2100, the territory of the country with insufficient humidity will increase up to 56 and 71%, respectively. As a result of such changes, there is a high probability of medium and long-term prospects of increasing arable land with insufficient natural moisture supply up to 20.6 million hectares (67%) and up to 24.9 million hectares (80%) with a simultaneous decrease in arable land with sufficient natural moisture supply up to 5.5 - 1.8 million hectares. At present, the potential total evaporation is 40-45 km3/year higher than in 1990. As a result, despite the decrease in water consumption, the total amount of water consumption taken from the territory of Ukraine is 20-25 km3 higher. Further climate change will lead to an increase in the volume of additional water consumption till 2050 by 80 km3, and till 2100 - by almost 150 km3 compared to 1990. Modern climate change has significantly affected the cropping systems and their productivity at regional level. The average yield of grain and legumes in the Forest-Steppe and Polissya compared to 1990 increased by 46-61%, and in the Steppe it decreased by 10%. A similar trend is observed with regard to the changes in the productivity of other major cereals, except corn, the yield of which increased in all areas, but in the Forest-Steppe and Polissya by 71-82%, and in the Steppe - only by 9%. The general increase in the production of grain and legumes in the country for the last years was only due to more humid regions - Polissya and Forest-Steppe. Climate change, which has already taken place, proved to be favorable for the spread of the most economically profitable crops in the north of the country, while limiting their production in the south. Thus, in the face of climate change, the conditions of moisture supply in the territory of Ukraine are the main limiting factor that limits not only the level of crop productivity, but also the use of natural and anthropogenic potential of agriculture.

Atmospheric Moisture as a Factor of Land Degradation Neutrality in Forest–Steppe Landscapes

Analysis of data from meteorological observations near the Kursk Biosphere Station, Institute of Geography, Russian Academy of Sciences, for the past 40 years shows a steady increase in temperature against the background of an increasing deficit of precipitation in this area. At the same time, the precipitation is characterized by a high instability and a contrast distribution by year, as well as by an increase in the number and duration of dry periods. Precipitation (in particular, snow accumulation) is an important source of moisture and a significant factor of functioning for forest–steppe landscapes. It is shown that different landscape types can have a two- to fourfold difference in snow accumulation, which plays a decisive role in the formation of moisture reserves. Agrolandscapes are deficient in moisture, which contributes to deeper freezing of soils, as well as to the deterioration of their water permeability and the development of a surface snowmelt runoff from fields, which leads to landscape degradation. The essence of the concept of land degradation neutrality, which mainly concerns the maintenance of global sustainable land use, is to obtain objective parameters for state of landscapes and to assess the proportion of lands exposed to degradation. Atmospheric moisture in forest–steppe landscapes is a significant factor determining their functioning and can be used as a local indicator of the concept.

Thermal Oxidation Kinetics of Multi-Walled Carbon Nanotubes in an Oxygen Flow

The oxidation reactions of multi-walled carbon nanotubes in isothermal conditions have been studied for the first time. With a steady increase in temperature from 923 to 1173 K, the time dependence for the oxidation of multi-walled carbon nanotubes changes from a straight line to an S-shaped curve that reaches its saturation point. The sample’s oxidation rate on linearly increasing sections at 923 K is Vox = 4.38 · 10–7 mole/sec. Internal overheating of the sample activates rapid carbon oxidation reactions on the $$ {360}^{{\mathrm{t}}_{\mathrm{h}}} $$ sec at 973 K. In the range 1023–1173 K, the total rates increase exponentially: Vox = 1.19 · 10–6–1.97 · 10–5 mole/sec. The Arrhenius equation was used to calculate the kinetic parameters of carbon thermal oxidation. The activation energies for the oxidation reactions of multi-walled carbon nanotubes in the range 973–1173 K were found at Ea ≈ ≈ 169 ± 9 kJ/mol. The frequency characteristics of factor A0 were defined as ≈ (1.0–3.1) · 106 sec–1. The activation parameters of the oxidation reactions of multi-walled carbon nanotubes are close to the theoretical activation energy of graphite oxidation (172 kJ/mole).

Rapid fatigue life prediction for spot-welded joint of SUS301 L-DLT stainless steel and Q235B carbon steel based on energy dissipation

Spot welding of dissimilar materials can utilize the respective advantage comprehensively, of which reliable prediction of fatigue life is the key issue in the structure design and service process. Taking into account almost all the complex factors that have effects on the fatigue behavior such as load level, thickness, welding nugget diameter, vibrational frequency, and material properties, this article proposed an energy dissipation-based method that is able to predict the fatigue life for spot-welded dissimilar materials rapidly. In order to obtain the temperature gradient, the temperature variations of four-group spot-welded joint of SUS301 L-DLT stainless steel and Q235 carbon steel during high-cycle fatigue tests were monitored by thermal infrared scanner. Specifically, temperature variation disciplines of specimen surface were divided into four stages: temperature increase, temperature decrease, continuous steady increase in temperature, and ultimate drop after the fracture. The material constant C that a spot-welded joint of dissimilar material needs to reach fracture is 0.05425°C·mm3. When the specimen was applied higher than the fatigue limit, the highest error between experimental values and predicted values is 18.90%, and others are lower than 10%. Therefore, a good agreement was achieved in fatigue life prediction between the new method and the validation test results.

Comparative Investigation and Operational Performance Characteristics of a Wick Assisted and Axially Square Grooved Heat Pipe

The present work reported here involves the experimental investigation and performance evaluation of wick assisted and axially square grooved heat pipes of outer diameter 8mm, inner diameter 4mm with a length of 150mm.The objective of this work is to design, fabricate and test the heat pipes with and without an axial square groove for horizontal and gravity assisted conditions. The performance of the heat pipes was measured in terms of thermal resistance and heat transfer coefficients. In the present investigation four different working fluids were chosen namely acetone, ethanol, methanol and distilled water. Experiments were conducted by varying the heat load from 2 W to 10 W for different fill charge ratios in the range of 25% to 75% of evaporator volume for wick assisted heat pipe and 8 W to 18 W for axially square grooved heat pipe. From the experiments, it was found that there is a steady increase in temperature with the increase in heat input. The overall heat transfer coefficient was found to increase with the increase heat load for wick assisted heat pipe. In case of axially square grooved heat pipe, an attempt was made to experiment the heat pipe in different orientations. The maximum heat transfer coefficient of 7000 W/m2 °C is found for Acetone at 180° orientation.

Spatiotemporal Changes of Reference Evapotranspiration in the Highest-Latitude Region of China

Reference evapotranspiration (ET0) is often used to make management decisions for crop irrigation scheduling and production. In this study, the spatial and temporal trends of ET0 in China’s most northern province as well as the country’s largest agricultural region were analyzed for the period from 1964 to 2013. ET0 was calculated with the Penman-Monteith of Food and Agriculture Organization of the United Nations irrigation and drainage paper NO.56 (FAO-56) using climatic data collected from 27 stations. Inverse distance weighting (IDW) was used for the spatial interpolation of the estimated ET0. A Modified Mann–Kendall test (MMK) was applied to test the spatiotemporal trends of ET0, while Pearson’s correlation coefficient and cross-wavelet analysis were employed to assess the factors affecting the spatiotemporal variability at different elevations. The results from this study showed a clear decreasing trend for annual ET0 from the low elevation plain area to the high elevation mountainous area. Over the past five decades, ET0 in Heilongjiang Province decreased in all seasons, except for the winter months, during which a steady increase in temperature was found. Elevation played an important role in estimating ET0 in this higher-latitude region, while relative humidity was the most relevant meteorological factor that affected the spatiotemporal variation of ET0 in the province. Overall, the findings from the study suggest that winter ET0 in a high altitude region will continue to increase in the future as climate change persists, which could worsen spring droughts and irrigation management for semi-arid areas in the province.

Understanding Climate Change and Manifestation of its Driven Impacts in the Semi Arid Areas of Dodoma Region, Tanzania

This article examines the nature and manifestation of climate change driven impacts on the agrarian districts of Kongwa and Bahi in the semi arid areas of Dodoma region in Tanzania. A Survey of 398 households in the study area was undertaken to elicit information on the nature and manifestation of climate change driven impacts. Household and key informant interviews and focus group discussion were used in collection of primary data. Secondary data were obtained through documentary review and from the Tanzania Meteorological Agency for the case of climatic data. The results indicate that climate change in Dodoma region is evident as revealed by steady increase in temperature and wind speed and the general declining rainfall trend overtime. Consequently, such changes in weather parameters over time has severely affected the livelihoods of local communities as manifested through decline in crop production, loss of livelihood sources, shortage of water and pasture for livestock, and difficulties in feeding household members overtime among others. Given the findings, this article concludes that climate change and its impacts in the area are real and hence climate change interventions should focus on increasing agricultural productivity, pasture for livestock through sustainable livestock keeping and land use planning, diversification of socio-economic activities, as well as sustainable utilization and management of natural resources. Keywords: Climate change; manifestation; local communities; semi arid areas, climate change impacts.

Geostatistical Analysis of Rainfall Temperature and Evaporation Data of Owerri for Ten Years

Rainfall, evaporation and temperature data of Owerri for ten years (Figure 1) (1998-2007) were acquired. The data were analyzed using standard statistical measures and climatological normal (Figure 2). The results show that the rainfall pattern exhibits some oscillations indicating annual bimodal distribution of rainfall. The temperature reached its lowest value of 27.75?C in 1999. Thereafter, a steady increase in temperature was noticed. From 2002, some variation in evaporation data was observed. The potential evapotranspiration shows some correlation with temperature. This variation in weather parameters may be attributed to climate change.

Estudio de tendencias climáticas y generación de escenarios regionales de cambio climático en una cuenca hidrográfica binacional en América del Sur

Despite the fact that there is no agreement among scientists about global warming, climate change, and their effects, there is no doubt that the availability of water resources depends to a great extent on climate. With the purpose of seeking evidence of climate change, the tendencies of the historical series of rainfall and temperature recorded in 40 climate stations located in the Ecuadorian-Peruvian border were studied by applying a fourth order moving average filter. After considering two different scenarios of climate evolution which were proposed by the IPCC, and applying 8 general circulation models, future regional scenarios of rainfall and temperature towards the year were generated toward the future years of 2025, 2050 and 2080. Evidence of climate change was found, and increasing trend of temperature, which is consistent with the volume of emissions of greenhouse gases. According to the scenarios analyzed, considerable climate disorders are forecasted with a steady increase in temperature and an oscillating decrease in rainfall.

Effects of the North Atlantic Oscillation (NAO) on combined temperature and precipitation winter modes in the Mediterranean mountains: Observed relationships and projections for the 21st century

Previous research has identified the North Atlantic Oscillation (NAO) as one of the dominant atmospheric patterns on the temporal evolution of precipitation and temperature in the Mediterranean area. The NAO is seen to markedly affect snowpack variability and water resource availability in many mountain areas. This study investigated the influence of the NAO on winter precipitation and temperature variability, and on the occurrence of four winter climate modes defined on the basis of combined precipitation and temperature quantiles: warm and wet (WW), warm and dry (WD), cold and wet (CW) and cold and dry (CD). It is known that the occurrence of different winter modes is closely related to snow accumulation in mountains. The present study focused on 15 mountain areas in Mediterranean Europe, Morocco, Turkey and Lebanon. Global circulation models (GCMs) have been used to simulate the relationships between the NAO and winter modes for the next century under a moderate (A1B) greenhouse gas emissions scenario. The results show that for the majority of the mountain areas in the Mediterranean region, the occurrence of different winter modes was closely related to the NAO state, although the relationships were weaker in the easternmost part of the Mediterranean basin. GCMs have accurately simulated the observed relationships, and indicate that the NAO will continue to influence the occurrence of combined precipitation and temperature modes in coming decades. The GCMs also suggest enhanced winter NAOs in the future, which could lead to an increase in the frequency of dry modes. Moreover, as the simulations indicate a steady increase in temperature, winters classified as “cold” in the 21st century will be noticeably rarer compared with recent decades. The relationships between the NAO and snowpack may also change substantially in the future, especially in low altitude areas.

Catalytic partial oxidation of ethane to ethylene and syngas over Rh and Pt coated monoliths: Spatial profiles of temperature and composition

The catalytic partial oxidation of C 2H 6 over Pt and Rh coated monolithic supports (4.7 wt% M/α-Al 2O 3 45 PPI) was investigated with a capillary sampling technique for a range of C 2H 6/air ratios at constant inlet flow (∼8 ms contact time), with and without H 2 addition. Effluent data clearly indicate the differences in product distribution between catalysts and equilibrium. Rh effectively converts the reactant mixtures to syngas with ∼80% selectivity, whereas Pt produces C 2H 4 with ∼55% C-atom selectivity, while neither produces thermodynamically favored C. Spatially resolved measurements provide direct evidence of the multi-zone nature of the reactors. With Rh, complete conversion of O 2 occurs to produce mostly CO, H 2 and H 2O within the first 3 mm of catalyst, followed by a reforming zone to produce additional syngas. Pt consumes O 2 more slowly, which results in a steady increase in temperature along the reactor. Ethylene formation correlates to reactor temperatures >750 °C, regardless of C/O, in line with the onset of homogeneous reactions. Hydrogen addition tests (C 2H 6/O 2/H 2=2/1/2) clearly exhibit preferential oxidation of H 2 with O 2 over Pt, which shifts the maximum in temperature upstream while preserving a portion of the C 2H 6 for C 2H 4 production. H 2 addition modifies the concentration and temperature profiles minimally on Rh. The main differences between catalysts are the high reforming and O 2 consumption activity with Rh compared to Pt, which are likely responsible for differences in C 2H 4 yields.

Charge compensation by in- situ heating for insulating ceramics in scanning electron microscope

With a steady temperature increase under high vacuum (HV) in an environmental scanning electronic microscope, we observed charge-free characterization and fine secondary electron (SE) images in focus for insulating ceramics (alumina (Al 2O 3), aluminum nitride (AlN), pure magnesium silicate (Mg 2SiO 4)). The sample current I sc increased from −8.18×10 −13 to 2.76×10 −7 A for Al 2O 3 and −9.28×10 −12 to 2.77×10 −6 A for AlN with the temperature increased from 298 to 633 K. The surface conductance σ increased from 5.6×10 −13 to 5.0×10 −11/Ω for Al 2O 3 and 1.1×10 −12 to 1.0×10 −7/Ω for AlN with the temperature increased from 363 to 593 K. The SE image contrast obtained via heating approach in high vacuum with an Everhart–Thornley SE-detector was better than that via conventional approach of electron–ion neutralization in low vacuum (LV) with a gaseous SE-detector. The differences of compensation temperatures for charge effects indicate dielectric and thermal properties, and band structures of insulators. The charge compensation mechanisms of heating approach mainly relate to accelerated release of trapped electrons on insulating surface and to increase of electron emission yield by heating.

Post-Weld Heat Treatment Stress Relaxation in Zircaloy 4 Plasma Welds

We have studied the effect of a post-weld heat treatment on plasma arc welds on Zircaloy 4 plates. The samples consist of two 100 mm long, 50 mm wide, and 6.25 mm thick plates, welded along the rolling (longitudinal) direction. The heat-treatment consisted of a steady increase in temperature from room temperature to 450oC over a period of 4.5 hours; followed by cooling with an equivalent cooling rate. Residual strains and stresses along the longitudinal, transverse and normal directions on an as-welded and a heat-treated specimen were measured by neutron diffraction on the ENGIN-X beamline at the Isis Facility, Rutherford Laboratory, UK. Peak tensile stresses of (105±25) MPa were found in the as-welded specimen, which were reduced to (70±20) MPa after the heat-treatment. Thermal compressive stresses of (-80±20) MPa were found along the normal direction, which were not affected by the heat treatment. The use of a full-pattern Rietveld refinement for the determination of bulk strains in Zircaloy specimens is also discussed.

Differential Thermal Analysis: Effect of Particle Size

SINCE differential thermal analysis involves the approach to equilibrium while the conditions are regularly changing (steady temperature increase), the recorded temperature of transformation depends on the reaction rate. This rate is affected by a catalyst. Rees1 states that although the theory of catalytic action is only just being established, the dominant role of defects is generally accepted. More defects cause a decrease in the degree of crystallinity, which lowers the recorded temperature of transformation, as shown by the experimental results quoted by van der Marel2.