Abrupt Increase In Temperature Research Articles

Postglacial ocean methane release from the northern South China Sea

Methane release into seawater and the atmosphere as a result of cold seepage activity is a sensitive indicator of global environmental change during the last glacial period. However, the link between postglacial ocean methane escape and possible increases in atmospheric methane concentration remains unclear, which hinders the evaluation of methane impact on climatic variability. In this study, lipid biomarkers were analyzed on samples from the Shenhu area in the South China Sea to reconstruct the marine gas hydrate variability since the last glacial time. The reconstructed methane release during the cool Last Glacial Maximum and Younger Dryas agreed well with previous findings. Interestingly, our results identified a pronounced methane outgassing at the end of Heinrich 1, which was likely triggered by the abrupt increase in intermediate water temperature. The occurrence of this gas hydrate dissociation before the drastic rise in atmospheric methane during Bølling-Allerød implied that the change in the gas hydrate reservoir could likely indirectly contribute to the initiation of the warming event, though more global evidence needs to be provided in the future.

Historical global and regional spatiotemporal patterns in daily temperature

The abrupt increase in surface air temperature over the last few decades has received abundant scholarly and popular attention. However, less attention has focused on the specific nature of the warming spatially and seasonally, using high-resolution reanalysis output based on historical temperature observations. This research uses the European Centre for Medium-range Weather Forecasts (ECMWF) Reanalysis Version 5 (ERA5) output to identify spatiotemporal features of daily mean surface air temperature, defined both as the mean of the maximum and minimum temperatures over the calendar day (“meanmaxmin”) and as the mean of the 24 hourly observations per day (“meanhourly”), across the terrestrial Earth. Results suggest temporal warming throughout the year, with several “hot spots” of significantly increasing temperature, including in the Arctic transition seasons, Northern Hemisphere mid-latitudes in July, Eurasia in spring, Europe and the lower latitudes in summer, and tropical autumn. Cooling is also observed, but generally at rates more likely to be statistically insignificant than warming rates. These trends are nearly identical regardless of whether calculated as “meanmaxmin” or “meanhourly.” These results may assist scientists and citizens to understand more fully observed agricultural, commercial, ecological, economic, and recreational trends in light of climate change considerations.

Research on the underground gasification of lignite through an oxygen enrichment process: insights from experimental study and Aspen Plus process model.

Underground coal gasification (UCG) can convert coal resources to high-calorific value syngas, which is important for the exploration of resources and the application of clean coal technology. This study investigated the gasification process of lignite in Heilongjiang Province through an oxygen enrichment approach and examined the impact of the oxygen concentration on the gasification efficiency. Furthermore, a high-fidelity Aspen Plus process model was designed to predict the gasification products of lignite. These findings indicate that the abrupt increase in the gasification temperature and pressure is governed by the concentration of oxygen in the gasification agent. An increased concentration of oxygen results in a higher gasification temperature, thereby influencing the thermodynamic reaction processes within the gasifier. The combustion reaction of lignite transitions into a coke reaction when the oxygen concentration is elevated to 90%. At this time, the relative concentration of CO2 generated from lignite combustion progressively diminished from 78.33%, while the relative concentrations of H2 and CO produced through coke reactions gradually increased from 3% and 2.07%, respectively. When the oxygen concentration reaches 100%, the relative contents of H2 and CO generated through gasification reach their respective maxima, measuring 18.90% and 23.91%. The calorific value attained a peak of 6.65 MJ N-1 m-3 simultaneously. Furthermore, the ash yield of lignite may be a critical factor influencing the process of underground coal gasification. The gasification efficiency of lignite near T 6 is suboptimal when the oxygen concentration falls below 100%, potentially attributable to the influence of ash. In summary, lignite in Heilongjiang Province can be effectively developed through underground gasification technology via an oxygen enrichment process. Furthermore, the Aspen Plus model we developed can effectively assist in predicting the products of lignite gasification in Heilongjiang Province.

Effects of Bi2O3 phase transition on sintering behavior, microwave dielectric properties of novel CeO2–Bi2O3 ceramics

Series of novel Bi2O3–CeO2 (Bi:Ce = 1:4∼6:1) ceramics were successfully fabricated, and the effects from both phase transition and content variation of Bi2O3 on the sintering temperature, microstructure and microwave dielectric properties had been investigated. The phase composition of Bi2O3–CeO2 series ceramics were indexed as CeO2 (Fm-3m) and Bi2O3 (P-421c or P21/c). Ceramics with Bi2O3 of P21/c phase had the optimum sintering temperature below 900 °C, which was suitable for LTCC. When Bi:Ce ratio changed from 1:2 to 1:3, the Bi2O3 phase changed from P21/c to P-421c, leading to an abrupt increase in the optimal sintering temperature (from 860 °C to 1000 °C), and also resulted in microstructure of Bi2O3–CeO2 ceramics evolving from vague to clear. For microwave dielectric properties, the dielectric constant and temperature coefficient were dependent on the content of Bi2O3, while the Q × ƒ values were related to the microstructure, which was affected by phase transition and content of Bi2O3. And the typical microwave dielectric properties were εr = 29.0–32.5, Q × ƒ = 17648 GHz–24278 GHz, τƒ = −20.77 ppm/°C ∼ −38.76 ppm/°C.

Calorimetry of a phase slip in a Josephson junction

Josephson junctions are a central element in superconducting quantum technology; in these devices, irreversibility arises from abrupt slips of the quantum phase difference across the junction. This phase slip is often visualized as the tunnelling of a flux quantum in the transverse direction to the superconducting weak link, which produces dissipation. Here we detect the instantaneous heat release caused by a phase slip in a Josephson junction, signalled by an abrupt increase in the local electronic temperature in the weak link and subsequent relaxation back to equilibrium. Beyond the advance in experimental quantum thermodynamics of observing heat in an elementary quantum process, our approach could allow experimentally investigating the ubiquity of dissipation in quantum devices, particularly in superconducting quantum sensors and qubits.

EXPERIMENTAL INVESTIGATION OF FLOW BOILING PARAMETERS IN A TRANSVERSE GROOVED HORIZONTAL TUBE: CRITICAL HEAT FLUX, PRESSURE DROP, AND HEAT TRANSFER COEFFICIENT

An experimental investigation was conducted to examine critical heat flux (CHF), boiling pressure drop, and local heat transfer coefficient in a horizontal channel with transverse grooves for flow boiling with R-123. Measurement of the wall temperature of the channel was done using a thermal camera. Five test sections were used for the study. A combination of groove pitch (<i>p</i>) of 18.6 and 11 mm and groove height (<i>e</i>) of 1 mm and 0.55 mm were used for the study. The groove pitch-to-height (<i>p/e</i>) ratios used were 11, 20, 18.6, and 33.8. Experiments were carried out for different heat fluxes in the range from 180 to 1259 kW/m<sup>2</sup>, six different mass fluxes from 180 to 1259 kg/m<sup>2</sup>s, and Reynolds numbers from 5834 to 51770. In the grooved channel compared with the smooth tube, an improvement in heat transfer and CHF with the higher pressure drop was found. The boiling heat transfer coefficient increases with a decrease in (<i>p/e</i>) ratio. The enhancement of heat transfer coefficient and CHF improves with a decrease in (<i>p/e</i>) ratio. The maximum enhancement of CHF for (<i>p/e</i>) ratios of 11, 18.6, 20, and 33.8 is found to be 134%, 87%, 57%, and 53%, respectively. An abrupt increase in test channel wall temperature is an indication of CHF occurring. CHF was observed at the top portion of the grooved channel and was found to be of departure from nucleate boiling type.

Ascophyllum nodosum and Silicon-Based Biostimulants Differentially Affect the Physiology and Growth of Watermelon Transplants under Abiotic Stress Factors: The Case of Drought

Climate change is an inevitable process characterized by an abrupt increase in global temperature and a decrease in precipitations leading to drought incidents. Biostimulants could be a valuable tool for mitigating these harsh conditions. The objective of our study was to test the efficiency of two biostimulants, a silicon-based seaweed and the seaweed Ascophyllum nodosum, to mitigate the drought stress endured by watermelon transplants during the first few weeks after transplanting. In order to achieve this, three water treatments (100%, 75%, and 50% of field capacity) were applied in pots. Important growth parameters (leaf number, fresh weight, and plant area) deteriorated depending on water availability. This was also the case for the root system development displayed by root dry weight, total length, and surface area. It is the first time the OJIP transient has been evaluated after the application of A. nodosum for drought-stressed plants. Chlorophyll fluorescence parameters showed that the photosynthetic apparatus was more stressed when A. nodosum was applied, especially in the harshest conditions (i.e., 50% field capacity). Overall, the silicon-based biostimulant failed to demonstrate drought-mitigating potential compared to the non-treated counterparts. On the other hand, A. nodosum alleviated the negative effects of water deficit, especially in the harshest conditions.

Esophageal Protection and Temperature Monitoring Using the Circa S-Cath™ Temperature Probe during Epicardial Radiofrequency Ablation of the Pulmonary Veins and Posterior Left Atrium

Although epicardial bipolar radiofrequency ablation should diminish the risk of esophageal thermal injury in comparison to an endocardial ablation, cases of lethal atrio-esophageal fistula have been reported. To better understand this risk and to reduce the possibility of a thermal injury, we monitored the esophageal temperature with the Circa S-Cath™ temperature probe during and immediately after the ablation while implementing three procedural safety measures. Twenty patients (15 males; 63 ± 10 years) were prospectively enrolled (November 2019-February 2021). All patients underwent an epicardial ablation procedure, including an antral left and right pulmonary vein isolation with bidirectional bipolar clamping, and a roof and inferior line using unidirectional bipolar radiofrequency. Three procedural preventive mitigations were implemented: (1) transesophageal echocardiographic visualization of the atrio-esophageal interface, with probe retraction before the energy delivery; (2) lifting the ablated tissue away from the esophagus during an energy application; and (3) a 30 s cool-off and irrigation period after the energy delivery. The esophageal temperature was recorded using an insulated multisensory intraluminal esophageal temperature probe (Circa S-Cath™). Of the 20 patients enrolled, 7 patients had paroxysmal atrial fibrillation (AF), 8 persistent AF and 5 longstanding persistent AF. The average maximum luminal esophageal temperature observed was 36.2 ± 0.7 °C (34.8-38.2 °C). In our clinical experience, no abrupt increase in the luminal esophageal temperature above the baseline was observed. Since no measurements exceeded the threshold of 39 °C, no prompt interruption of energy delivery was required. Intraluminal esophageal temperature monitoring is feasible and can be helpful in confirming correct catheter position and safe energy application in bipolar epicardial left atrial ablation. Intra-procedural preventive mitigations should be implemented to reduce the risk of esophageal temperature rises.

Prolonged Controlled Oxygenated Rewarming Improves Immediate Tubular Function and Energetic Recovery of Porcine Kidneys During Normothermic Machine Perfusion.

Normothermic machine perfusion (NMP) is typically performed after a period of hypothermic preservation, which exposes the kidney to an abrupt increase in temperature and intravascular pressure. The resultant rewarming injury could be alleviated by gradual rewarming using controlled oxygenated rewarming (COR). This study aimed to establish which rewarming rate during COR results in the best protective effect on renal rewarming injury during subsequent NMP. Twenty-eight viable porcine kidneys (n = 7/group) were obtained from a slaughterhouse. After these kidneys had sustained 30 min of warm ischemia and 24 h of oxygenated HMP, they were either rewarmed abruptly from 4-8 °C to 37 °C by directly initiating NMP or gradually throughout 30, 60, or 120 min of COR (rate of increase in kidney temperature of 4.46%/min, 2.20%/min, or 1.10%/min) before NMP. Kidneys that were rewarmed during the course of 120 min (COR-120) had significantly lower fractional excretion of sodium and glucose at the start of NMP compared with rewarming durations of 30 min (COR-30) and 60 min (COR-60). Although COR-120 kidneys showed superior immediate tubular function at the start of normothermic perfusion, this difference disappeared during NMP. Furthermore, energetic recovery was significantly improved in COR-30 and COR-120 kidneys compared with abruptly rewarmed and COR-60 kidneys. This study suggests that a rewarming rate of 1.10%/min during COR-120 could result in superior immediate tubular function and energetic recovery during NMP. Therefore, it may provide the best protective effect against rewarming injury.

Metallic Material Evaluation of Liquid Hydrogen Storage Tank for Marine Application Using a Tensile Cryostat for 20 K and Electrochemical Cell

A series of material tests were performed on cryogenic metallic materials meant for liquid hydrogen storage tanks using a 20 K tensile cryostat and an electrochemical hydrogen-charging apparatus. Mechanical evaluation of the electrochemically hydrogen-charged specimens was performed in a tensile cryostat using helium gas at ambient temperature and cryogenic temperature (20 K). The tensile cryostat was equipped with a vacuum jacket and a G-M cryocooler with gaseous helium. Furthermore, the cathodic electrolysis cell used for charging the specimens was adopted for internal hydrogen conditions with a reflux condenser and heating mantle to increase hydrogen diffusivity. The target materials were austenite stainless steel and aluminum alloy, which are suitable for liquefied natural gas and gaseous hydrogen environments. No significant change in the yield strength and flow stress of the hydrogen-charged specimen up to 20% strain was observed. However, changes in tensile strength and elongation were observed thereafter. Electrochemical hydrogen charging of stainless steel leads to a high concentration of hydrogen on the surface of the specimen. The resulting surface cracks reduced the flow stress. The 20 K tensile test showed discontinuous yielding in the austenitic stainless steel with an abrupt increase in temperature. The mechanical performance of the aluminum alloys improved in terms of strength and elongation. Changes in the mechanical performance and relative area reduction were observed for all the metallic materials at 300 K and 20 K.

The effect of abrupt increase in water temperature on the survival and growth of eelgrass Zostera marina

Increased water temperature is considered an important cause of the loss of seagrass beds. This paper quantified the interactive influence of different combinations of water temperature and duration on the responses of Zostera marina plants in terms of survivorship, morphology, growth and physiology. The LT50 (lethal temperature that caused an increase in mortality to 50% of that of the control) and ET50 (effect time that caused a decrease in growth to 50% of that of the control) were calculated to reveal the quantitative relationship between temperature and duration that resulted in limiting effects on the survival and growth of Z. marina plants. Z. marina plants were exposed to different combinations of water temperature [23 (control), 25, 27, 29, and 31 °C] and duration (5, 10, 15 and 20 days), and then the plants were transferred to the control condition for over 30 days under laboratory conditions. The results showed that the survival rate of plants at the end of recovery were significantly lower than those of plants at the end of direct impact under the temperature levels of 29 and 31 °C in each duration, indicating that short-term periods of obviously increased water temperature would lead to long-term effects on the survival of Z. marina plants. Regression analysis revealed that the relationship between water temperature and duration that resulted in limiting effects on the survival and growth of Z. marina could be described as a strong power function. Pearson correlation analysis showed that the survival and growth of Z. marina plants exposed to different temperature levels were significantly correlated with leaf soluble sugar contents. This study will further develop our understanding of the degradation and disappearance of seagrass beds induced by increased temperature.

Optical cavitation in non-absorbent solutions using a continuous-wave laser via optical fiber

Optical cavitation can be induced by short pulse lasers focused into a solution with a low absorption coefficient or using a continuous-wave laser focused into highly absorbent solutions. In this work, we report the generation of cavitation bubbles in ethanol using a continuous-wave fiber optic laser with emission at 450 nm wavelength. Silver and copper nitrate nanoparticles were immobilized on the flat end-face of a multimode optical fiber tip using the photodeposition technique and then immersed into the solution. Laser light transmitted through the optical fiber is strongly absorbed by both nanoparticles causing an abrupt increase in temperature around the tip of the optical fiber, reaching the spinodal limit of ethanol (∼187 °C). At this temperature, an explosive phase transition (liquid–gas) occurs causing the generation of a microbubble, which grows until reaches its maximum radius (∼1072 μm in 132 µs) and subsequently collapses, emitting a shock wave. The dynamic behavior of the gas bubble was studied as a function of the laser power using a high-speed video camera, and the shock wave emitted immediately after the bubblés collapse was detected by a microphone. The pressure of the shock wave was analyzed photodepositing different thin films of silver nanoparticles at the tip of the optical fiber, causing optical attenuations of 1, 3, 5, and 7 dB. The experimental results obtained showed that when a thin film of copper nitrate nanoparticles was photodeposited on a film of silver nanoparticles (5 dB), the pressure of the shock wave increases up to ∼ 13-fold, in comparison, if we use only one film of silver nanoparticles. Energetic shock waves have potential applications in a variety of areas such as medicine, biological sciences, material processing, liquid microjets generation, among others.

Effects of maternal intake of docosahexaenoic acid on febrile status epilepticus and increased susceptibility to seizures after growth

Febrile seizures are caused by an abrupt increase in body temperature. They are sometimes recurrent, and the more seizures are triggered, the higher the risk of epilepsy and psychiatric disorders increase after growing up. Prevention of febrile seizure is considered to be one of the effective countermeasures in protecting the future health of children. Docosahexaenoic acid (DHA) is an important nutrient especially during pregnancy and childhood and is reported to suppress several types of epilepsy. Therefore, we challenged maternal DHA intake to prevent febrile seizures and secondary epilepsy after growth in mice. We used a heat chamber for febrile seizure induction. Intake of DHA during pregnancy and infancy increased the amount of DHA in the brain of offspring. DHA prolonged the seizure latency and increased body temperature at which the first seizure occurred, indicating that maternal DHA intake decreases febrile seizure sensitivity. The mice with febrile status epilepticus showed increased susceptibility to seizures induced by pentylenetetrazol. DHA intake during infancy suppressed the appearance of excitatory electroencephalography and prolonged the seizure latency. Collectively, DHA intake during pregnancy and infancy is of significance in protecting infant from seizures as well as conserving health after growth.

Maternal intake of docosahexaenoic acid decreased febrile seizure sensitivity by increasing estrogen synthesis in offspring

Febrile seizures, which are convulsion in children, are caused by an abrupt increase in body temperature. They are sometimes recurrent, and the more seizures are triggered, the higher the risk of epilepsy and psychiatric disorders increase after growing up. Prevention of febrile seizure is considered to be one of the effective countermeasures in protecting the future health of children; however, pharmacological prevention in the developmental stage is not realistic from the health aspects of the offspring. Docosahexaenoic acid (DHA) is an important nutrient especially during pregnancy and childhood and is reported to suppress several types of epilepsy. The purpose of this study was to examine the effect of DHA intake during pregnancy and infancy on febrile seizures in mice. We used a heat chamber for febrile seizure induction in offspring at the age of from 10 to 11 days old. Intake of DHA during pregnancy and infancy significantly increased the amount of DHA in the brain of offspring. Although DHA had no effect on seizure severity, DHA significantly prolonged the seizure latency and increased body temperature at which the first seizure occurred, indicating that maternal DHA intake decreases febrile seizure sensitivity. Brain estrogen levels significantly increased by DHA intake and administration of an inhibitor for cytochrome P450 aromatase, which is a rate-limiting enzyme for estrogen synthesis, clearly decreased seizure latency and body temperature at which the first seizure occurred. Taken together, DHA could reduce susceptibility to febrile seizures owing to increases in brain estrogen contents. DHA intake during pregnancy and infancy is of significance in protecting infant from seizures as well as conserving health after growth.

Flash‐Sintering Mechanism Studied Through Interrupted Experiments

Herein, the mass‐transfer mechanism of flash sintering during the transient stage is examined using an in‐house‐made flash and quench (FQ) system. Visual findings of samples during and after FQ experiments and high‐resolution electron microscopy are given. Many new observations regarding the flash‐sintering nature are presented and discussed. Samples that underwent FQ experiments either show no sign of sintering or local sintering and grain growth due to a hotspot. These findings aid in untying of the two phenomena. Electron microscopy imaging of flash and quenched samples shows atypical microstructures. Such microstructural anomalies include sintering, massive grain growth, and visual findings on the surface. These findings establish flash sintering as a set of phenomena, caused by an abrupt and local increase in temperature (a “flash event”), where only one of which is sintering.

Larval drift dynamics, thermal conditions and the shift in juvenile capelin distribution and recruitment success around Iceland and East Greenland

Global warming is not uniformly distributed, the climate is expected to change most rapidly in the arctic regions. Large scale changes in the arctic biosphere is therefore of particular concern. Capelin (Mallotus villosus) is a keystone species in the many arctic marine ecosystem including the seas around Iceland in Greenland. Its summer/autumn distribution has shifted over thousands of kilometres and production has decreased substantially. Multiple drivers may be involved in this change. Here, we explore the roles of changes in larval drift and thermal conditions around spawning and the larvae. Using model based simulations of the period 1993–2015, we find that vertical behaviour of the larvae, geographical distribution of the spawning and to some extent also timing of the spawning affect the drift trajectories. Our results from the simulations indicate large interannual variation in westwards drift, but without a long-term trend. The shift in distribution of the capelin did consequently not appear to result from a large scale shift in currents. Unlike the current, ambient temperature had a long term trend, and the temperature level changed abruptly and significantly between 2002 and 2003. The long-term shift in distribution might have been driven by the warming through a combination of earlier and more northern spawning and mortality dynamics. However, the timing of the shift in temperature (from 2003) was not in agreement with the timing of the events during the shift (starting in 2002). The first year may, on the other hand, be explained by the strong westwards currents particularly in 2002. Also, we point out a striking match between the abrupt increase in ambient temperature and the observed decrease in recruitment from 2003.

Selection by Genetic Expression Profiles of Desi and Kabuli Chickpea (Cicer arietinum L.) Genotypes Tolerant to High Temperature Stress

Background: Mexico is an important producer of chickpea; however, high temperatures during flowering and grain filling limit seed yield and seed size. Plant adaptation strategies to heat stress depend on climatic and soil conditions, but mainly on the plant genetic characteristics. The increase in heat shock proteins (HSP) production occurs when plants experience an abrupt or gradual increase in temperature in order to whithstand stress with the least damage. Methods: Sixty-five Heat Shock Protein related genes that induce transcription under heat stress were studied according to their expression profiles. This strategy allows for the selection of chickpea genotypes bearing potential heat stress tolerance. Based on the number of overexpressed (induced) genes and on its level of expression, a tolerance index was calculated. Result: Tolerant desi genotypes were: ICC 10259, ICC 13020, ICC 4958 and Annigeri; and in the kabuli type outstanding genotypes were: Mazocahui, ICCV 2, Blanco Sinaloa 92, Tequi Blanco 95, Combo 743 and CUGA 08-1210. These genotypes showed profiles with a higher number of induced genes and higher Tolerance Indexes. These genotypes will be further evaluated in the field and under controlled conditions and in the near future used as parental stocks.

Flow structure at different stages of heat transfer deterioration with upward, mixed turbulent flow of supercritical CO2 heated in vertical straight tube

The mixed turbulent heat transfer characteristics of supercritical CO2 heated in a straight tube of diameter d = 4 mm are experimentally and numerically investigated at a pressure p = 8 MPa, mass flux G = 278 kg/(m2s), heat flux q = 15–35 kW/m2, and inlet Reynolds number Rein ≥ 14000. To identify the key factor affecting the heat transfer deterioration (HTD), the flow structures at different conditions are comparatively analyzed. The results show that the HTD accompanying abrupt increase in the wall temperature is mainly caused by buoyancy force rather than thermal acceleration. The M-type velocity profiles are observed at the initial, stable, and recovery stages of the HTD. The location of the salient point of the M-type velocity plays a major role in the different regions of the HTD. Similar to the salient point of the M-shaped velocity, the location at which the local fluid temperature Tb(r) is equal to the pseudo-critical temperature Tpc can also be an effective criterion for predicting the onset of HTD. Both the salient point of the M-shaped velocity and the location of Tb(r) = Tpc demonstrate that the flow structure at the buffer layer (y+ = 5–30) is the dominant factor that influences the onset of HTD. An analysis of the thermal resistance in cross section also confirms that the buffer layer is the dominant region for the HTD. Based on the analysis of the flow states at the buffer layer, a new correlation model is developed for accurately predicting the heat transfer coefficient of supercritical CO2 under the HTD condition.

Stability evaluation of radial growth of Picea schrenkiana in different age groups in response to climate change in the eastern Tianshan Mountains

Global warming causes an unstable response in tree radial growth at high latitudes in the Northern Hemisphere. Additionally, different climatic responses of different age groups of trees have been found due to their different physiological mechanisms. In this study, the response stability and growth trend of three age groups (young < 100a, middle 100–200a, old ≥ 200a) of Picea schrenkiana (Schrenk spruce) to climate change and the causes of the different responses in different age groups were analyzed in the relatively dry climate of the eastern Tianshan Mountains. The results showed that: (1) With the abrupt increase in temperature in 1989, the annual mean minimum temperature became the dominant radial growth-limiting factor of the three age groups of Schrenk spruce. (2) The radial growth of the middle and young groups was more sensitive than that of the old group based on growth-climate correlation analysis. (3) The radial growth of the different age groups had different responses to climate factors, and all age groups were unstable on time scales. (4) The trend of the linear regression simulation of the basal area increment (BAI) indicated that the Schrenk spruce had the same growth trends in different age groups with growth first increased and then decreased; however, the decreased growth rate was higher in the middle and young age groups than in the old age group after the abrupt increase in temperature. Therefore, we should pay active attention to the impact of drought on Schrenk spruce in the eastern Tianshan Mountains and should particularly strengthen the conservation and management of the middle and young age groups.

Effects of airborne hydrocarbon adsorption on pool boiling heat transfer

During pool boiling, a significantly high heat flux leads to the transition from nucleate boiling to film boiling, where a vapor film forms over the boiling surface, drastically increasing thermal resistance. This transition at the critical heat flux (CHF) results in an abrupt increase in surface temperature and can lead to catastrophic failure of the boiler. However, reported CHF values vary greatly, even for smooth surfaces of the same material; for example, the CHF values on flat silicon and silicon dioxide surfaces vary across studies by up to 49% and 84%, respectively. Here, we address this discrepancy by accounting for hydrocarbon adsorption on boiling surface. Hydrocarbon adsorption on smooth boiling surfaces decreases surface wettability, hindering the ability to maintain liquid contact with the surface and, thus, lowering the pool boiling CHF. To investigate hydrocarbon adsorption kinetics under ambient conditions and the subsequent effect on CHF, we cleaned flat silicon dioxide samples with argon plasma to remove hydrocarbon contaminants and then exposed them to laboratory air for different periods of time before conducting pool boiling experiments. Pool boiling results along with x-ray photoelectron spectroscopy data showed that the amount of adsorbed hydrocarbon increased with exposure time in air, which resulted in a decrease in wettability and, accordingly, a decrease in CHF. This work has important implications for understanding the spread in CHF values reported in the literature and may serve as a guideline for the preparation of boiling surfaces to achieve consistent experimental results.