Sudden Temperature Drop Research Articles

Chronic and severe hypoxic conditions in Paracas Bay, Pisco, Peru: Consequences on scallop growth, reproduction, and survival

The response of Argopecten purpuratus (Peruvian scallop) to environmental conditions was studied in the upwelling-influenced Bay of Paracas (Peru). Scallops growth and reproduction were monitored weekly over a 7-month period under two conditions (culture depths): on the bottom and 2 m above (suspended culture). At the same time, a high-frequency environmental monitoring was realized at the aforementioned depths. The results indicate that environmental conditions in the Bay are highly variable, especially during the summer: temperature fluctuations up to 8∘C were recorded in less than one day while oxic conditions ranged from oversaturation to anoxia. Milky-turquoise waters discoloration events (sulphide presence suspected) were simultaneously observed together with anoxic conditions and sudden temperature drops. Increased stratification and upwelling favorable winds during the summer might be partly responsible for the observed environmental variability. Higher somatic and gonadal growth were observed in scallops growing in suspended culture compare with bottom culture. This pattern might be related to different environmental conditions at culture depth: turbidity was lower in suspended culture and hypoxic conditions occurred only 18% of the whole study period versus 48% on the bottom. The Gonadosomatic index varied according to an approx. 30-day cycle between winter and late spring and it was synchronous between the different scallop size groups. During summer, when milky waters and anoxic events occurred frequently, cessation of reproduction, somatic weight losses and increased scallop mortality were observed. Exposure to severe hypoxia and related environmental conditions clearly affected scallop bioenergetics and subsequently growth and reproduction. In addition, the occurrence of milky waters harmed the survival of the Peruvian scallop in culture. These results are discussed in terms of management strategies for sustainable scallop aquaculture in the Bay.

Effect on horizontal pressure in steel silos evoked by a sudden change in the ambient temperature

The Eurocode EN 1991-4 includes provisions which refer to the stress increase in structural members evoked by the temperature differential between the silo wall and the stored material. This Eurocode presents in the clause 5.6 the formula on increase of horizontal pressure as a result of the temperature differential between the silo wall and the stored material. The derivation of this formula by two different approaches was presented in this work. Theoretical considerations were exemplified by chosen examples showing the effort increase of the silo wall as a result of a sudden cooling of the silo wall. Silos of different slenderness and of different coefficients of wall friction were considered. The performed analysis has revealed that in every case the formula based on the plane strain assumption gave higher values of the horizontal pressure increase. Calculations have revealed that the sudden temperature drop of the silo wall by 20 °C can lead even to the 35 % increase of horizontal pressure. Results of analytical solutions were supplemented by numerical simulations which have confirmed correctness of the formulae derived in this work. The alternative formula based on the plane strain assumption should replace the recommended in Eurocode formula based on the plane stress case.

Heat transfer analysis of magnesium alloy plate during transport process

Abstract Temperature detection and tracking of AZ31B magnesium alloy plate during the air-cooling transport process were investigated and carried out under different thicknesses and initial temperatures. Experimental results show that there exists a sudden temperature drop in the range of 1/4 of width distanced from the edge. When the plate is cooled by 25–56 °C, the maximum inhomogeneous temperature distribution under all process conditions will appear in width direction. For the air-cooling transport process, the temperature control model for predicting the average temperature of the Mg plate after a predetermined time period can be established by modifying the Stefan-Boltzmann empirical equation. The model mainly depends on the plate specifications and air-cooling time.

Nucleation of thermal cracks at the wall of a rock mass

The conditions of cracks nucleation due to thermal shock at the wall of a rock mass are examined and a nucleation length as well as a time delay of crack occurrence with respect to the thermal shock initial time is estimated. The results are applied to geophysical heat shock problems, such as temperature drop at a cavern wall or a sudden drop of temperature in a well.

Cold- and menthol-evoked membrane potential changes in the moss Physcomitrella patens: influence of ion channel inhibitors and phytohormones.

Microelectrode measurements carried out on leaf cells from Physcomitrella patens revealed that a sudden temperature drop and application of menthol evoked two types of different-shaped membrane potential changes. Cold stimulation evoked spike-type responses. Menthol depolarized the cell membrane with different rates. When it reached above 1 mV s-1 , the full response was recorded. Characteristic for the full responses was also a few-minute plateau of the membrane potential recorded after depolarization. The influence of inhibitors of calcium channels (5 mM Gd3+ ), potassium channels (5mM Ba2+ ), chloride channels (200 μM Zn2+ , 50 μM niflumic acid) and proton pumps (10μM DES), an activator of calcium release from intracellular stores (Sr2+ ), calcium chelation (by 400 μM EGTA) and phytohormones (50 μM auxin, 50 μM abscisic acid (ABA), 500 μM salicylic acid) on cold- and menthol-evoked responses was tested. Both responses are different in respect to the ion mechanism: cold-evoked depolarizations were influenced by Ba2+ and DES; in turn, menthol-evoked potential changes were most effectively blocked by Zn2+ . Moreover, the effectiveness of menthol in generation of full responses was reduced after administration of auxin or ABA, i.e. phytohormones known for their participation in responses to cold and regulation of proton pumps. The effects of DES indicated that one of the main conditions for generation of menthol-evoked responses is inhibition of the proton pump activity. Our results indicate that perception of cold and menthol by plants proceeds in different ways due to the differences in ionic mechanism and hormone dependence of cold- and menthol-evoked responses.

Liposomes with cyclic RGD peptide motif triggers acute immune response in mice

Liposomes with peptides motifs have been widely applied for targeted delivery of anticancer drugs. However, few studies have questioned whether peptide modification on liposomes may induce serious toxicity associated with immune stimulation. Here, we report that display of a tumor targeting cyclic RGD peptide (e.g. c(RGDyK) and c(RGDfK) on the surface of liposomes can be a potent inducer of lethal hypersensitivity-like reactions in mice upon re-administration, with the main symptom a sudden drop in body temperature. The hypothermia usually abates within 4 h but is sometimes lethal with death happening within 30 min post injection. This reaction has been proven to be IgE-independent acute systemic anaphylaxis, which may due to IgG immune complex triggered complement activation, anaphylatoxin and cytokine release, etc., leading to acute conspicuous organ damage. Results from an exploration of influence factors showed that the immunotoxicity of c(RGDyK)-liposomes could not be eliminated by minimizing the c(RGDyK) motif ratio, or by decreasing injection doses in the normal dose range, or by increasing the mPEG-DSPE motif ratio. However, encapsulation of a strong cytotoxic drug completely shut off this unwanted immune response. Investigation with a series of peptides containing the RGD sequence suggested that the lethal immunotoxicity of the cyclic RGD peptide was RGD sequence and peptide cyclization dependent. This study provides a valuable alert for the utilization of peptide modified liposomes in drug delivery, especially when carrying low-toxicity drugs.

Temporal proteomics of Arabidopsis plasma membrane during cold- and de-acclimation

Freezing stress is one of the most important limiting factors of plant survival. Plants have developed a freezing adaptation mechanism upon sensing low temperatures (cold acclimation). Compositional changes in the plasma membrane, one of the initial sites of freezing injury, is prerequisite of achieving cold acclimation and have been investigated in several plant species. Conversely, the cold dehardening process at elevated temperatures (de-acclimation) has not yet been fully characterized and few studies have addressed the importance of the plasma membrane in the de-acclimation process. In the present study, we conducted shotgun proteomics with label-free semiquantification on plasma membrane fractions of Arabidopsis leaves during cold acclimation and de-acclimation. We consequently obtained a list of 873 proteins with significantly changed proteins in response to the two processes. Although the cold-acclimation-responsive proteins were globally returned to non-acclimated levels by de-acclimation, several representative cold-acclimation-responsive proteins tended to remain at higher abundance during de-acclimation process. Taken together, our results suggest plants deharden right after cold acclimation to restart growth and development but some cold-acclimation-induced changes of the plasma membrane may be maintained under de-acclimation to cope with the threat of sudden freezing during de-acclimation process. SignificancePlant freezing tolerance can be enhanced by low temperature treatment (cold acclimation), while elevated temperatures right after cold acclimation can result in the dehardening of freezing tolerance (de-acclimation). However, the de-acclimation process, particularly its relevance to the plasma membrane as the primary site of freezing injury, has not been elucidated. In the present study, a comprehensive proteomic analysis of the plasma membrane during cold acclimation and de-acclimation was carried out as a first step to elucidating how plants respond to rising temperatures. Cold acclimation induced a number of proteomic changes as reported in previous studies, but most proteins, in general, immediately returned to NA levels during de-acclimation treatment for two days. However, the abundances of stress-related proteins (e.g. LTI29, COR78 and TIL) decreased slower than other functional proteins during de-acclimation. Therefore, plants harden during cold acclimation by aborting growth and development and accumulating stress-responsive proteins but seem to deharden quickly under subsequent elevated temperature to resume these processes while guarding against the threat of sudden temperature drops.

Remote Sensing of Coastal Upwelling in the South-Eastern Baltic Sea: Statistical Properties and Implications for the Coastal Environment

A detailed study of wind-induced coastal upwelling (CU) in the south-eastern Baltic Sea is presented based on an analysis of multi-mission satellite data. Analysis of moderate resolution imaging spectroradiometer (MODIS) sea surface temperature (SST) maps acquired between April and September of 2000–2015 allowed for the identification of 69 CU events. The Ekman-based upwelling index (UI) was applied to evaluate the effectiveness of the satellite measurements for upwelling detection. It was found that satellite data enable the identification of 87% of UI-based upwelling events during May–August, hence, serving as an effective tool for CU detection in the Baltic Sea under relatively cloud-free summer conditions. It was also shown that upwelling-induced SST drops, and its spatial properties are larger than previously registered. During extreme upwelling events, an SST drop might reach 14 °C, covering a total area of nearly 16,000 km2. The evolution of an upwelling front during such intensive events is accompanied by the generation of transverse filaments extending up to 70 km offshore. An analysis of the satellite optical data shows a clear decline in the chlorophyll-a concentration in the coastal zone and in the shallow Curonian Lagoon, where it drops down by an order of magnitude. It was also shown that a cold upwelling front alters the stratification in the atmospheric boundary layer, leading to a sudden drop of air temperature and near-surface winds.

Experimental investigation of the compression and heating of an MHD-driven jet impacting a target cloud

Adiabatic compression has been investigated by having an MHD-driven plasma jet impact a gas target cloud. Compression and heating of the jet upon impact were observed and compared to theoretical predictions. Diagnostics for comprehensive measurements included a Thomson scattering system, a fast movie camera, a translatable fiber-coupled interferometer, a monochromator, a visible-light photodiode, and a magnetic probe array. Measurements using these diagnostics provided the time-dependent electron density, electron temperature, continuum emission, line emission, and magnetic field profile. Increases in density and magnetic field and a decrease in jet velocity were observed during the compression. The electron temperature had a complicated time dependence, increasing at first, but then rapidly declining in less than 1 μs which is less than the total compression time. Analysis indicates that this sudden temperature drop is a consequence of radiative loss from hydrogen atoms spontaneously generated via three-body recombination in the high-density compressed plasma. A criterion for how fast compression must be to outrun radiative loss is discussed not only for the Caltech experiment but also for fusion-grade regimes. In addition, the results are analyzed in the context of shocks the effects of which are compared to adiabatic compression.

The adoption of thermosiphon powered, ground level phosphine application systems in Australia.: Presentation

Safe storage of grain on Australian farms requires a sealable silo to exclude grain insects and enable effective fumigation to avoid the development of insect resistance to phosphine. A sealable silo must also be fitted with a pressure relief system that allows air to enter the silo rapidly, to avoid damage to the silo fabric, in the event of a sudden temperature drop and subsequent contraction of the internal atmosphere. The most effective pressure relief system allows air into the headspace by a pipe attached to the silo wall, which is connected to an oil bath valve at ground level to facilitate servicing. The oil bath valve prevents grain insects entering and will allow air to bypass when the internal pressure exceeds or falls below 30 – 40 Pascals. The addition of a pipe connecting the headspace pipe to the base of the silo creates a gas recirculation loop. Ambient temperature influences the air within the external pipe and Thermosiphon currents are created, circulating the internal atmosphere. In 2004, a silo manufacturer in Western Australia proposed such a recirculation loop adding an aluminium phosphide (AlP) reaction chamber into the circuit at ground level. A ground-level application system removes the need to climb the silo, making fumigation simpler and safer. Initial experiments in 2005 revealed that the phosphine gas would be extracted from the reaction chamber by Thermosiphon air movement, without building to dangerous concentrations. Seven silo manufacturers across Australia have adopted the Thermosiphon recirculation system linked to a ground level AlP reaction chamber, producing nearly 12,000 transportable silos of 80 – 100t capacity in that period. The development of the recirculation system and effectiveness of Thermosiphon gas distribution is discussed in this paper.

Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) overwintering: an overview

AbstractThe Dacini fruit flies are tropical and subtropical insects for which a winter diapause is largely unknown. However, some pest dacines have extended their geographic ranges into temperate areas where winter temperatures may be limiting. During the 1900s, Bactrocera tryoni (Froggatt) extended its Australian endemic tropical range to include temperate southern Australia. Starting nearly 100 years ago, several research teams have spent considerable effort understanding how ‘tropical’ B. tryoni survives temperate winters: this review summarises that research. Across three study areas (Sydney and surrounding districts, New South Wales; Melbourne and surrounding districts, Victoria; Stanthorpe, south‐eastern Queensland), there is highly consistent data showing that the fly overwinters almost exclusively in the adult form. Eggs, larvae and pupae generated in late autumn or early winter either fail to develop due to lack of sufficient day‐degree accumulation or if immature development is successful and adults emerge, then those adults do not become sexually mature until the spring. Females which are already sexually mature when entering winter resorb some or all of their eggs. During winter, adults rest in sheltered locations and will forage for food on warm days. In field cages, mortality of adults is approximately 8% per week during winter, and so significant adult mortality occurs during winter. Based on laboratory studies, adult survival at cool to cold (15°C to −4°C) temperatures is increased if the fly or earlier developmental stages (pre‐pupal maggots and fully developed pupae) undergo an acclimation process, rather than being subjected to a sudden drop in temperature. Early climate change modelling suggests that a decrease in the number of extreme cold events (i.e. hard frosts) is more likely to lead to improved fly survival in temperate areas than the overall mean temperature increase. Gaps in knowledge include quantification of what makes a preferred overwintering site; how climate change over the last 30 years (when the last detailed experiments were done) have modified overwintering phenologies; and where on the Australian east coast does temperature become limiting such that year‐round breeding ceases.

Validation of a dynamic model for vapor bubble growth and collapse under microgravity conditions

A complete set of ordinary differential equations, based on modifications of existing models, is used to investigate bubble growth and collapse under microgravity conditions in this paper. As in previous work, effects of inertia, surface tension and viscosity are taken into consideration in the momentum equation of the liquid phase outside of vapor bubble, while effects of “moving interface”, interface curvature and thermal resistance of surrounding liquid are considered in the evaporation of the vapor bubble. A dimensionless fitting constant b is introduced to account for area change of the moving vapor/liquid interface and the diffusive nature of the interface layer. The values of these fitting constants for bubble growth and bubble collapse in water and ethanol are obtained by matching predicted temporal variations of bubble radii with experimental data. The predicted interfacial dynamics during bubble growth and bubble collapse is analyzed. Different stages during the bubble growth process are characterized. During the early stage of bubble collapse, the simulated bubble radii show some “fluctuations”, which can be attributed to the “rebound effect” of pressure balance in the bubble owing to the initial condition of a sudden drop in temperature.

Simulation as a decision tool in construction process management in turbulent environment

This paper is dedicated to simulation idea of construction process for decision-making aid. An aim is to improve technological decisions for concreting operation at low temperature. A risk of destruction of concrete structure is a critical problem in this situation. A sudden drop in temperature may result in disqualification of the concrete element or the entire structure. The proposed solution is based on a simulation of the process of maturing of the concrete element based on experiments in the laboratory (e.g. heat of hydration and dynamics of growth of compressive strength depending on the temperature). The case study proved that the traditional approach to the management of concreting technology (based on one 48-hour forecast) is extremely risky when operating in a turbulent and changing environment. The proposed flexible approach is based on systematically updated simulation and is more effective thanks to the possibility of activating active flexible procedures to prevent freezing of concrete in case of pessimistic scenario.

Wax Behavior in Crude Oils by Pour Point Analyses

Crude oils containing large quantities of waxes, and in situations where sudden temperature drops occur, a crystalline network can be formed, generating flow difficulties in production, transfer and offloading lines. Despite the scientific and economic importance of this phenomenon, correlations between the behavior of petroleum in relation to its pour point are scarce in the literature. In this work, nine crude oil samples were characterized regarding density, water content, wax fraction (one- and two-dimensional chromatography), pour point, yield stress and wax appearance temperature. The results showed that the storage conditions and oil characteristics had a strong influence on the pour point. Yield stress was influenced by initial temperature of the sample, cooling rate and shear rate during cooling. Finally, the content of aromatic compounds in oil with low concentration of n-alkanes can contribute to increase the pour point.

Trichostatin A and 5-Aza-2′-Deoxycytidine influence the expression of cold-induced genes in Arabidopsis

ABSTRACTThe expression of cold-induced genes is critical for plants to survive under freezing stress. However, the underlying mechanisms for the decision of when, where, and which genes to express are unclear when a plant meets a sudden temperature drop. Previous studies have demonstrated epigenetics to play a central role in the regulation of gene expression in plant responses to environmental stress. DNA methylation and histone deacetylation are the two most important epigenetic modifications. This study was conducted to investigate the effects of inhibiting DNA methylation and histone deacetylation on gene expression, and to explore the potential role of epigenetics in plant responses to cold stress. The results revealed that histone deacetylase inhibitors (trichostatin A) and DNA methylation inhibitors (5-Aza-2′-deoxycytosine) treatment enhanced cold tolerance. DNA microarray analysis and the gene ontology method revealed 76 cold-induced differently expressed genes in Arabidopsis thaliana seedlings that were treated to 0°C for 24 h following Trichostatin A and 5-Aza-2′-Deoxycytidine. Furthermore, analyses of metabolic pathways and transcription factors of 3305 differentially expressed genes were performed. Each four metabolic pathways were significantly affected (p < 0.01) by Trichostatin A and 5-Aza-2′-Deoxycytidine. Finally, 10 genes were randomly selected and verified via qPCR analysis. Our study indicated that Trichostatin A and 5-Aza-2′-Deoxycytidine can improve the plant cold resistance and influence the expression of the cold-induced gene in A. thaliana. This result will advance our understanding of plant freezing responses and may provide a helpful strategy for cold tolerance improvement in crops.

Effect of temperature-dependency of material properties on thermal shock fracture of solids associated with non-Fourier heat conduction

This paper investigates the thermal shock fracture behavior of a cracked semi-infinite medium with temperature-dependent material properties. The medium is subjected to a sudden temperature drop at its surface and all material properties are the functions of temperature. The temperature field and associated thermal stress in the medium without cracking are obtained by using the Laplace transform method and the numerical technology of Laplace inversion. The thermal stress intensity factors at the crack tip are obtained by using the weight function method. The thermal stress intensity factor and crack growth behavior are analyzed numerically by comparing the temperature-dependent model with temperature-independent model. The studies indicate the significance of temperature-dependent material properties on the thermal shock fracture and crack growth behavior of solids for high-temperature applications.

Growth and cold hardening of European aspen seedlings in response to an altered temperature and soil moisture regime

During the autumn, plants undergo a physiological process of cold hardening to limit damage caused by the low temperatures of winter. Under a warming climate, plants may be less cold hardened and hence more susceptible to the effects of a sudden temperature drop. During the growth season of 2010–2011, growth and cold hardening of European aspen (Populus tremula L.) seedlings from native wild populations were examined under ambient and projected climate scenarios in greenhouses at the Haapastensyrjä research station in Southern Finland. Using locally obtained seedlings, we manipulated temperature and soil moisture during the normal growth period and then subjected them to an artificial freezing treatment during September–November 2010. At the end of the experiment, we determined seedling height, survival and the extent of stem damage, and analysed their variation with mixed effect models.Among the treatments tested, temperature was the main factor affecting survival, cold hardening, and frost damage to seedlings. The higher temperature (4°C increase) of the 2100 future climate regime was associated with a 35% decrease in seedling survival (from 66 to 31%) during the growing period. Increased irrigation had a positive, but considerably weaker effect on seedling survival (improved survival by ca. 8%). Height of seedlings after the first growth season was enhanced by increased soil moisture and temperature, but these effects were negated the following spring by increased frost damage caused by warmer growth conditions. Although cold hardiness increased as the season progressed, increase of temperature by 1 and 4°C severely diminished it, and survival after the freezing dropped from 55% (control) to 48% and 14%, while stem damage increased from 58% (control) to 90% and 96%, respectively. These results suggest that regeneration of north European aspen might become burdened in a warmer climate. Although survival was clearly affected, several seedlings grown under the future climate regimes survived freezing and overwintered with negligible damage, suggesting an adaptive capacity of the local population. The intraspecific competition that occurred as a side effect of the experimental setup also affected cold hardening, suggesting that stand structure might be managed to improve the resilience of aspen to frost damage.

Different Cold-Signaling Pathways Function in the Responses to Rapid and Gradual Decreases in Temperature.

In plants, cold temperatures trigger stress responses and long-term responses that result in cold tolerance. In Arabidopsis thaliana, three dehydration-responsive element (DRE) binding protein 1/C-repeat binding factors (DREB1/CBFs) act as master switches in cold-responsive gene expression. Induction of DREB1 genes triggers the cold stress-inducible transcriptional cascade, followed by the induction of numerous genes that function in the cold stress response and cold tolerance. Many regulatory factors involved in DREB1 induction have been identified, but how these factors orchestrate the cold stress-specific expression of DREB1s has not yet been clarified. Here, we revealed that plants recognize cold stress as two different signals, rapid and gradual temperature decreases, and induce expression of the DREB1 genes. CALMODULIN BINDING TRANSCRIPTION ACTIVATOR3 (CAMTA3) and CAMTA5 respond to a rapid decrease in temperature and induce the expression of DREB1s, but these proteins do not respond to a gradual decrease in temperature. Moreover, they function during the day and night, in contrast to some key circadian components, including CIRCADIAN CLOCK ASSOCIATED1 and LATE ELONGATED HYPOCOTYL, which regulate cold-responsive DREB1 expression as transcriptional activators only during the day. Thus, plants efficiently control the acquisition of freezing tolerance using two different signaling pathways in response to a gradual temperature decrease during seasonal changes and a sudden temperature drop during the night.

Investigation of baffle configuration effect on the performance of exhaust mufflers

Using baffles in exhaust mufflers is known to improve their transmission loss. The baffle cut ratio should affect the muffler performance analogous to a shell-and-tube heat exchanger. To the authors’ knowledge, there is no previous assessment reported in literature of the effects that the baffle cut ratio configuration has on acoustic response and back pressure. This investigation presents a parametric study on the effect of baffle configuration on transmission loss and pressure drop predicted. The effect of (i) the baffle cut ratio and baffle spacing, (ii) the number of baffle holes, and (iii) the hole distribution for their effect on transmission loss was investigated. Results show that decreasing the baffle cut ratio tends to increase the transmission loss at intermediate frequencies by up to 45%. Decreasing the spacing between muffler plates was shown to enhance the muffler transmission loss by 40%. To assess the baffle effect on flow, the OpenFoam CFD libraries were utilized using the thermal baffle approach model. Baffles were found to cause sudden drop in fluid temperature in axial flow direction. The outlet exhaust gases temperature was found to decrease by 15% as the baffle cut ratio changed from 75% to 25%.

Lattice Boltzmann simulations for transition from dropwise to filmwise condensation on hydrophobic surfaces with hydrophilic spots

Transition from dropwise to filmwise condensation of a dry saturated vapor on downward-facing smooth subcooled horizontal hydrophobic walls with hydrophilic spots is simulated numerically using the newly developed phase-change lattice Boltzmann method. Dynamic behaviors including growth, coalescence and departure of condensate droplets from cooler surface are investigated. Effects of wall subcooling and wettability of the cooler surface on droplet departure diameter, average cycle time and nucleation time are presented. At small wall subcoolings, droplets are formed on hydrophilic spots of the hydrophobic surface. With increasing wall subcoolings, coalescence of droplets and their subsequent departure are observed. Further increase of the wall subcooling leads to transition from dropwise condensation to filmwise condensation mode, and droplets fall down from the subcooled surface at locations according to Taylor’s unstable wavelength. The dropwise condensation curve in terms of average heat flux versus wall subcooling from droplet nucleation to peak condensation heat flux and its subsequent transition to filmwise condensation is obtained numerically for the first time. It is found that the location where droplet or liquid film in contact with the downward-facing surface has a high local heat flux, especially around the triple-phase contact line. The degree of wall subcooling corresponding to peak condensation heat flux increases with the increasing pitch distance between hydrophilic spots. The cooler’s hydrophobic surface with a smaller contact angle has a lower peak condensation heat flux which occurs at a smaller degree of wall subcooling. During transition from dropwise to filmwise condensation, there is a graduate reduction in wall heat flux under constant wall temperature conditions, and a sudden drop in the average wall temperature of the subcooled surface under constant wall heat flux conditions.