Rapid Temperature Decrease Research Articles

Effect of Cellulose Nanocrystals on the Properties of Cement Paste

The effect of the addition of cellulose nanocrystals (CNCs) on the properties of cement pastes is studied herein. The compressive strength of CNC/cement paste was investigated under the curing conditions defined in this study. Two-dimensional micrographs and pore size distributions were obtained by scanning electron microscopy, X-ray computed tomography (XCT), and nitrogen adsorption. The addition of CNCs was found to significantly enhance the mechanical properties of cement pastes with a rapid decrease in temperature and humidity. XCT and nitrogen adsorption analyses show that the addition of CNCs leads to a refinement of the pore structure in the cement matrix. Almost no hydration products, including C-S-H, are formed in the cement matrix without CNCs under extreme conditions. This is in contrast with the results for the cement paste with 0.5% CNCs.

3-Iodothyronamine Induces Diverse Signaling Effects at Different Aminergic and Non-Aminergic G-Protein Coupled Receptors

The thyroid hormone metabolite 3-iodothyronamine (3-T1AM) exerts diverse physiological reactions such as a decrease of body temperature, and negative inotropic and chronotropic effects. This observed pleomorphic effect in physiology can be barely explained by interaction with only one target protein such as the trace-amine receptor 1 (TAAR1), a class A G-protein coupled receptor (GPCR). Moreover, Taar1 knock-out mice still react to 3-T1AM through physiological responses with a rapid decrease in body temperature. These facts propelled our group and others to search for further targets for this molecule.The group of TAARs evolved early in evolution and, according to sequence similarities, they are closely related to adrenoceptors and other aminergic receptors. Therefore, several of these receptors were characterized by their potential to interplay with 3-T1AM. Indeed, 3-T1AM acts as a positive allosteric modulator on the beta2-adrenoceptor (ADRB2) and as a biased agonist on the serotonin receptor 1B (5HT1b) and the alpha2-adrenoceptor (ADRA2A). In addition, 3-T1AM was reported to be a weak antagonist at a non-aminergic muscarinic receptor (M3).These findings impressively reflect that such trace amines can unselectively and simultaneously function at different receptors expressed by one cell or at different tissues. In conclusion, the role of 3-T1AM is hypothesized to concert the fine-tuning of specific cell reactions by the accentuation of certain pathways dependent on distinct receptors. 3-T1AM acts as a regulator of signals by blocking, modulating, or inducing simultaneously distinct intracellular signaling cascades via different GPCRs.

Reduced fluids in porphyry copper-gold systems reflect the occurrence of the wall-rock thermogenic process: An example from the No.1 deposit in the Xiongcun district, Tibet, China

High fO2 conditions characterize the majority of global porphyry copper deposits and contain highly oxidized minerals, such as magnetite and anhydrite. In contrast, the No. 1 porphyry Cu–Au deposit in the Xiongcun district (Tibet, China) has abundant pyrrhotite, reduced fluids (CH4 ≫ CO2), and a relative lack of highly oxidized minerals, which are indicative of low fO2 conditions. Scanning electron microscopy, fluid inclusion, C–H–O–He–Ar isotopes, and whole-rock organic carbon contents and isotope analysis were used to constrain the evolution of ore-forming fluid, the origin of CH4 and metal deposition mechanisms for the No. 1 deposit. The He–Ar isotopic compositions (3He/4He = 0.11–0.96 Ra, 40Ar/36Ar = 418.7–2920.2) suggest that the ore-forming fluids predominantly derived from crust source with minor mantle input. The H–O isotopic analysis results (δ18OH2O = −1.8 to +5.2‰, δD = −106 to −89.9‰) indicate that the ore-forming fluids were derived from a magmatic source that mixed with some meteoric waters. The element compositions of zircons and fluid/melt inclusions from the mineralized Middle Jurassic quartz diorite porphyry reveal that the primary magma was characterized by high log fO2 (>NNO) conditions. The quartz diorite porphyry intruded into the carbon-bearing wall rocks produced abundant CH4 by thermal decomposition of organic matter (δ13CCH4 = −26.3 to −28.5‰), which changed the redox state of the porphyry copper system from oxidized to reduced condition. Ore elements were deposited via fluid boiling as a consequence of the rapid decrease in temperature and pressure.

Near surface air temperature lapse rates over complex terrain: a WRF based analysis of controlling factors and processes for the central Himalayas

Various environmental processes are strongly controlled by spatio-temporal variations of surface air temperature (hereafter temperature) in complex terrain. However, the usually scarce network of observations in high mountain regions does not allow for an investigation of the relevant micro-meteorological processes that result in complex temperature fields. Climate impact studies often utilize a constant lapse rate of temperature (LRT hereafter) in order to generate spatially distributed temperature data, although it is well acknowledged that LRTs feature a pronounced variability at spatial, seasonal, and diurnal scales. In this study, the Weather Research and Forecasting (WRF) model is used to understand the factors and processes influencing temperature and LRT in the Khumbu and Rolwaling regions of the central Himalayas. A high resolution simulation is performed for one complete year (June 2014–May 2015) in order to capture the entire seasonal cycle. To test the model response to land cover and terrain characteristics, additional simulations with adjusted surface conditions are conducted. Our results demonstrate the capability of WRF to reproduce the processes controlling LRT, although an LRT bias is detected during non-monsoon seasons. The simulated temperature fields feature two LRT minima (i.e. low temperature decrease with elevation) during Nov–Dec and monsoon season, and two LRT maxima (strong temperature decrease with elevation) during the early post-monsoon and pre-monsoon seasons. A steeper LRT (i.e. a rapid decrease of temperature with elevation) is found at high elevations (> 4500 m) while shallower LRT values (i.e. a slower decrease or even increase of temperature with elevation) are apparent at lower elevations. During the pre-monsoon season, high net insolation rates and a reduced latent heat loss from snow free surfaces cause strong sensible heating at low elevations, while the presence of snow at high elevations leads to reduced sensible heating. This strong contrast results in steeper LRT values. Early post-monsoon shows similar characteristics but with a reduced magnitude. The shallow LRT during monsoon season is shown to be caused by the large-scale moisture supply and the associated latent heat release at the Himalayan slopes. This effect is further intensified due to strong up-valley winds which contribute to a well-mixed troposphere. Temperature inversions associated with cold air pooling cause shallow LRT values in lower river valleys during Nov–Dec. The results suggest that the identified processes should be considered for downscaling applications, particularly if distributed temperature fields are required for climate impact investigations.

Retarding the decay of temperature in the air flow field during the melt blowing process using a thermal insulation tube

During melt blowing, most of the polymer jet attenuation occurs in the area within 2 cm from the die, due to the rapid decrease of polymer jet temperature. Therefore, keeping the polymer jet temperature above melting point for a longer time is beneficial for its attenuation. Here, a thermal insulation tube with heating ability was introduced into the air flow field during the melt blowing process. The computational fluid dynamics technique was employed to investigate the effects of the thermal insulation tube on the air flow field. It was found that the thermal insulation tube has enhancing effects on the temperature, velocity, and turbulence kinetic energy of the air flow field. Experiments were conducted to examine the fiber diameters of the final nonwovens, the results of which indicates that a die with a thermal insulation tube can achieve a higher polymer jet attenuation and that the heating effect can further enhance the attenuation. Based on the computational fluid dynamics technique, the effects of the tube diameter and length on the temperature, velocity, and turbulence kinetic energy of the air flow field were investigated.

Uniform, Scalable, High-Temperature Microwave Shock for Nanoparticle Synthesis through Defect Engineering

Summary Here we demonstrate a thermal shock synthesis method triggered by microwave irradiation for the rapid synthesis of nanoparticles on reduced graphene oxide (RGO) substrate. With properly controlled reduction, RGO has high electrical conductivity while maintaining functional groups, leading to an extremely efficient microwave absorption of ∼70%. The high utilization of microwaves results in the ability to raise the temperature to 1,600 K in just 100 ms, which is followed by rapid quenching to room temperature. The defects on the RGO are crucial for achieving this record-high microwave-induced temperature as these defects play a fundamental role in absorbing the radiation as well as the self-quenching mechanism. By loading precursors onto RGO, we can utilize rapid temperature change to synthesize nanoparticles. The nanoparticles are ∼10 nm with uniform distribution. This facile, rapid, and universal synthesis technique has the potential to be employed in large-scale production of nanomaterials and suggests a new direction for nanosynthesis.

Causes and Impact of Cryopreservation-Associated Damage on Different Parameters of Human Spermatozoa and its Clinical Impact

Sperm cryopreservation has been widely used for assisted reproductive technology (ART). Indications for sperm cryopreservation include donor insemination, cryopreservation prior to surgical infertility treatment, and malignancies to avoid additional surgery in couples undergoing repeated in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) cycles. However, dramatic changes during cryopreservation have detrimental effects on the sperm membrane, resulting in a large increase in the percentage of poorly motile sperm or sperm with abnormal morphology. The negative effects related to rapid temperature decrease, such as osmotic injury, cellular dehydration, intracellular ice crystal formation, and oxidative stress can also damage the sperm in ways that affect reproductive outcome. This comprehensive review focusses on describing the detrimental effects of the cryopreservation process on sperm and aims to clarify that not all impaired sperm parameters have the same impact on the clinical practice of ART. Regarding the parameters studied, some of the biomarkers used for sperm maturity, hyaluronic acid binding capacity, or damaged DNA have limited clinical significance compared to other semen parameters which provide more useful information for clinical practice and are often dismissed, such as total motility or total motile sperm count (TMSC). In the authors’ experience, TMSC gives valuable quantitative information about the number of viable spermatozoa. Indeed, TMSC should be assessed specifically for groups of patients in which sample availability is limited.

PSV-4 Effect of drying and/or warming piglets at birth on rectal temperature over the first 24 hours after birth

Abstract Newborn piglets experience a rapid decrease in body temperature, increasing the risk of mortality. The objective of this study was to determine the effect of drying and/or warming at birth on piglet rectal temperature over 24 h after birth. The study was carried out at a commercial sow facility using a CRD with 4 treatments: Control (no drying or warming of piglets), Drying (piglets dried at birth using a cellulose-based desiccant), Warming (piglets placed in a box under a heat lamp for 30 min after birth), and Drying+Warming (piglets dried and warmed as above). Piglets were identified with a numbered ear tag. They were weighed at birth and rectal temperature was measured at 0, 10, 20, 30, 45, 60, 120, and 1440 min (24 h) after birth. Sows and litters were randomly allotted at birth to treatments. Data were analyzed using a repeated measures model with PROC MIXED of SAS. Litter was the experimental unit and piglet was a subsample of the litter; the model included the fixed effects of treatment and repeated time, and the interaction. Rectal temperature at birth was similar (P > 0.05) for all treatments. Subsequently, piglets on the Drying and Warming treatments had similar (P > 0.05) temperatures, which were greater (P 0.05) than the Control at all measurement times up to 120 min. Drying+Warming resulted in the highest (P < 0.05) rectal temperature overall and at most times of measurement between 10 and 120 min. Rectal temperatures were similar for all treatment at 24 h after birth. In conclusion, drying and/or warming piglets at birth significantly increased rectal temperatures between 10 and 120 minutes after birth with the combination of the two having the greatest effect. This research was funded by the National Pork Board.

Evolution of cyclic thermal stress in selective laser melting of 316L stainless steel: a realistic numerical study with experimental verification

It is well known that high thermal stresses in the formed parts during selective laser melting (SLM) heavily affect the part quality and performance. In this study, the mechanism of thermal stress formation due to temperature gradients in SLM of 316L stainless steel is investigated. The uniqueness of this study lies in the fact that a realistic multi-track and multi-layer SLM process is modeled and simulated that adopts the identical conditions of the actual part building on a commercial SLM system, and the final residual stresses are compared between the simulation and the experimental measurements on the actual parts. The results indicate that both temperature and stress evolution of material points exhibit cyclic patterns during the SLM process, and the changes with regard to time are dramatic thanks to the rapid heating and cooling of localized areas. However, the rapid temperature decrease is actually accompanied by stress increase in the material points, and vice versa. Under the laser power of 160 W and scanning speed of 500 mm/s, a melting pool is formed and rapidly expanded to the adjacent pre-solidified layer, and the diffusion depth is about 200 μm. Also, unlike the overall attenuation of temperature as the SLM build process progresses, the magnitude of stress oscillation actually increases. Furthermore, during the rapid solidification, the core of melting pool is subject to tensile stress. The tensile stress could be partially mitigated by the laser heating of subsequent layers, but it cannot be completely removed. As a result, the accumulation effect of multiple layers leads to significant tensile stress, in particular, in the bottom layers that are closer to the base plate. The effective stress in the bottom layer attached to the base plate reaches as high as 680 MPa based on the settings of SLM process. Finally, the experiment measurement on residual stress overall agrees with the simulation results. Both show that the residual stress ranges from 100 to 350 MPa for the layers 1.4 mm above the base plate, and that the tensile stress tends to increase along the direction towards the base plate.

The role of powder physicochemical properties on the extinction performance of an extinguishing powder for sodium fires

The French Atomic and alternative Energy Commission (CEA) aims to reuse its sodium fire (carbonate base) extinguishing powder after long term storage (stock from the dismantlement of its old sodium facilities). As the composition of the powder appears to change during the storage, the efficiency on the extinction as a function of the physicochemical properties was questioned. Small sodium fire extinction experiments were carried out with powders of different compositions. The results demonstrated a dominant role of water of crystallization on the extinction. Two steps are proposed for the extinction mechanism that includes: (1) the formation of liquid sodium hydroxide and (2) the melting of carbonate mixture at eutectic composition. The sodium hydroxide behaves as a protective layer and insulates the sodium surface from prolonged contact with oxygen. Consequently, it provides rapid decrease of temperature, unlike the slow melting of carbonates eutectic and its porous layer formed due to its higher viscosity. The presence of trona (aging product) does not alter the extinction capacity of the powder. To extrapolate the results to large fires, 35 g of water of crystallization are necessary to extinguish 1 m2 of sodium pool fire. Finally, the particle size appears to be a non-significant parameter to the quality of extinction except for the spreading performance.

Bubble Glow at Hydrothermal Vents as the <i>PeTa</i> Radiation

The paper presents a physical model of a natural phenomenon, the glow of bubbles at hydrothermal vents formed during underwater volcanic activity. The basis of the model is characteristic non-equilibrium radiation under first order phase transitions that since 2010 has been referred to as the PeTa (Perelman-Tatartchenko) effect. This is the fourth paper in a series developing the model for similar physical phenomena: cavitational luminescence (CL), multi-bubble sonoluminescence (MBSL), single-bubble sonoluminescence (SBSL) and laser-induced bubble luminescence (LIBL). The previous three papers were published during 2017-2018 in this Journal. In the third one we have shown that above mentioned physical effects can be generalized as a phenomenon that we have titled “Vapour bubble luminescence” (VBL). VBL is very clearly represented in a non-equilibrium phase diagram. The essence of VBL is as follows: when there is a local decrease in pressure and/or an increase of temperature in a tiny volume of a liquid occurs, one or several bubbles filled with vapour will appear. Subsequently a very rapid pressure increase and/or temperature decrease in the same volume of liquid leads to supersaturation of the vapour inside the bubble. Upon reaching critical vapor density, instantaneous vapour condensation and emission of the phase transition energy that is accompanied by a flash (this is the PeTa effect) results in a sharp pressure decrease and the bubble collapses due to the pressure drop. This process is accompanied by a shock wave in the liquid. A similar effect occurs if bubbles filled with hot steam, for example from a cappuccino machine, are injected into a relatively large volume of cold water. The VBL model explains all experimental data concerning CL/MBSL/SBSL/LIBL and the relatively new natural phenomenon, the glow of bubbles at hydrothermal vents. Several model experiments demonstrate the PeTa effect under similar conditions. Additionally, we define the PeTa effect in all its manifestations on a non-equilibrium phase diagram. This clarifies which niches can contain VBL processes. We also demonstrate the window of transparency (WT) for the PeTa radiation during crystallization of a supercooled tellurium melt and propose the design of a cavity-free pulsed laser on the basis of similar crystallization processes.

MRI-guided treatment in the breast.

In the last decades, an increasing interest has developed towards non-invasive breast lesion treatments, which offer advantages such as the lack of surgery-related complications, better cosmetic outcomes, and less psychological distress. In addition, these treatments could be an option for patients with poor health who are not candidates for surgery. Non-surgical ablation can be performed under magnetic resonance (MR) or ultrasound (US) guidance. US is cheaper and easily available, while contrast-enhanced MR is more accurate, ensuring better safety and efficacy for the patient. Overall results of studies about MRI-guided tumor ablation reported complete ablation rates ranging between 20% and 100%. High-intensity focused ultrasound (HIFU or FUS) is the most studied ablative technique and it is already established as a valid technique for ablation of benign and malignant tumors in various organs. Ultrasound-guided FUS is very useful for young patients who refuse surgery or with multiple nodules; however, MR-guided FUS is more sensitive and allows a better evaluation of thermal accumulation within the ablated tissue or the adjacent structures. Most MR-guided FUS studies used a dedicated high-field MR scanner and complete tumor ablation was reported in 17-90% of cases. Other techniques using thermal tissue destruction are radiofrequency ablation (RFA) and laser interstitial thermal therapy (LITT). Only a few studies assessed the efficacy of these treatments, all were performed with open MR devices. RFA showed complete tumor ablation in 30-96% of patients, while LITT in 10-71%, but all the studies had a small number of patients. Cryoablation obtains tissue ablation by a rapid decrease of temperature, with a complete tumor removal reported in 18-52% of cases with MR guidance. No serious complications were reported with these techniques. Currently, breast conservative surgery replaced radical surgery when possible. Therefore, future research should focus on these treatments to shift towards an even less invasive approach to breast neoplasms. Level of Evidence: 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018;48:1479-1488.

Gastrointestinal Telemetric Pills Used as Rectal Probes Provide Inaccurate Measurements of Absolute Rectal Temperatures

Continuous measurement of rectal temperature (RT) using a wired rectal probe (WRP) comes with obvious technical difficulties and practical limitations. Measurement of RT using a telemetric pill (TP) inserted as a suppository to act as a rectal probe would circumvent some of those problems. PURPOSE: Validate the use of a commercially available gastrointestinal TP (HQ Inc.) for the continuous measurement of RT during slow and rapid increase and decrease in core temperature induced by periods of passive cooling, passive heating, active heating and active cooling. METHODS: Nine (8 men, 1 woman) physically active participants (30 ± 9 yrs; 175 ± 7 cm; 75 ± 9 kg) underwent a research protocol where they completed, while wearing a WRP (YSI 401) linked to a TP: 1) a 30 min sitting period (23°C) followed by 2) a 45 min sitting period inside a head-out environmental chamber (40-42 °C); 3) a 45 min sitting period (23°C) while ingesting, over the first 30 min, 7.5 g of shaved-ice (-1°C )/kg body weight; 4) a running exercise period (38 °C, 20-30% RH) at 68% VO2max until a WRP temperature of 39.5°C and; 5) a cold-water (10°C) immersion period until a WRP decrease in temperature of 1.5°C. The WRP and each TP were calibrated before experiments. A bias ± random error contained within ± 0.35°C (daily variation in RT of ± 0.25°C + sensors measurement error of ± 0.1°C) around the zero line was deemed acceptable between sensors. RESULTS: The rate of change in WRP and TP temperatures during phases 1, 2, 3, 4 and 5 was respectively of -0.008 ± 0.007°C/min and -0.006 ± 0.004°C/min, 0.003 ± 0.005°C/min and 0.002 ± 0.004°C/min, -0.011 ± 0.004°C/min and -0.011 ± 0.002°C/min, 0.057 ± 0.010°C/min and 0.054 ± 0.008°C/min and -0.141 ± 0.124°C/min and -0.091 ± 0.065°C/min. Mean biases (WRP - TP) and random errors during phases 1, 2, 3, 4 and 5 were of 0.12°C/± 0.30°C, 0.15°C/± 0.22°C, 0.12°C/± 0.26°C, 0.21°C/± 0.34°C and 0.24°C/± 0.66°C, respectively CONCLUSION: The use of TPs (HQ Inc.) as suppositories tracked slow and rapid increases in RT and slow decreases in RT as measured by WRP, but did not detect the rapid decrease in RT. In all instances, however, the absolute difference between WRP and TP exceeded +/- 0.35°C. Therefore, we conclude that a TP inserted as a suppository to act as a rectal probe does not provide acceptable absolute measure of RT.

Core Temperature Monitoring in Obstetric Spinal Anesthesia Using an Ingestible Telemetric Sensor.

Perioperative hypothermia may affect maternal and neonatal outcomes after obstetric spinal anesthesia. Core temperature is often poorly monitored during spinal anesthesia, due to the lack of an accurate noninvasive core temperature monitor. The aim of this study was to describe core temperature changes and temperature recovery during spinal anesthesia for elective cesarean delivery. We expected that obstetric spinal anesthesia would be associated with a clinically relevant thermoregulatory insult (core temperature decrease >1.0°C). A descriptive study was conducted in 28 women. An ingestible telemetric temperature sensor was used to record core temperature over time (measured every 10 seconds). The primary outcome was the maximum core temperature decrease after spinal anesthetic injection. The secondary outcomes were lowest absolute core temperature, time to lowest temperature, time to recovery of core temperature, hypothermic exposure (degree-hours below 37.0°C), and the time-weighted hypothermic exposure (median number of degrees below 37.0°C per hour). Basic descriptive statistics, median spline smooth, and integration of the area below the 37.0°C line of the temperature-over-time curve were utilized to analyze the data. Intestinal temperature decreased by a mean (standard deviation) of 1.30°C (0.31); 99% confidence interval (CI), 1.14 to 1.46 after spinal anesthetic injection. The median (interquartile range [IQR]) time to temperature nadir was 0.96 (0.73-1.32) hours (95% CI, 0.88-1.22). Fourteen of the 28 participants experienced intestinal temperatures below 36.0°C after spinal injection. Temperature was monitored for a minimum of 8 hours after spinal injection. In 8 of 28 participants, intestinal temperature did not recover to baseline during the monitored period. A median (IQR) of 4.59 (3.38-5.92) hours (95% CI, 3.45-5.90) was required for recovery to baseline intestinal temperature in the remaining 20 patients. Participants experienced a median (IQR) of 1.97 (1.00-2.68) degree-hours of hypothermic exposure (95% CI, 1.23-2.45). The median (IQR) number of degrees below 37.0°C per hour was 0.45 (0.35-0.60) (95% CI, 0.36-0.58). During cesarean delivery under spinal anesthesia, women experienced a rapid decrease in core temperature. Using an intestinal telemetric sensor, the perioperative thermal insult and recovery were documented with high resolution. Fifty percent of participants in this study became hypothermic. Although the surgical procedure is typically of short duration, women undergoing spinal anesthesia for cesarean delivery experience significant hypothermic exposure and compromised thermoregulation for several hours.

Effects of Cyclic Thermal Loads on Bone-Implant Interface in Dental Prostheses

Background: Consumption of hot substances may harm the surrounding bone around a dental implant. High temperatures at the bone-implant interface (BII) interferes with local cellular activities involved in the osteointegration. Objectives: The present study was aimed at calculating the temperature distribution through the BII and the jaw bone under application of a transient cyclic thermal load. Methods: In this numerical simulation, finite element method was employed in a commercialized dental implant model drawn by computer-aided design tools based on CT data to find the temperature in superficial and deep bone regions near the BII. The heat load was applied cyclically during the intake time. Results: Results showed that the highest temperature was occurred at the top regions of the interface by magnitude of 48 C. Removal of the thermal loads also was followed by rapid decrease in the bone temperature. Conclusions: Routine beverages of a hot liquid can increase the temperature of the bone beyond the biological thresholds of the bone cells vitality or remodeling functionality, specifically in the delayed loading types of implantation.

Copper(II) ions interactions in the systems with triamines and ATP. Potentiometric and spectroscopic studies

The mode of interaction and thermodynamic stability of complexes formed in binary and ternary Cu(II)/ATP/triamines systems were studied using potentiometric and spectroscopic (NMR, EPR, UV–Vis) methods. It was found that in binary metal-free systems ATP/HxPA species are formed (PA: Spd=spermidine or 3,3-tri=1,7-diamino-4-azaheptane) where the phosphate groups from nucleotides are preferred negative centers and protonated amine groups of amines are positive centers of reaction. In the ternary systems Cu/ATP/Hx(PA) as well as Cu/(ATP)(PA) species are formed. The type of the formed Cu(II) complexes depends on pH of the solution. For a low pH value the complexation appears between Cu(II) and ATP molecules via oxygen atoms of phosphate groups. For a very high pH value, where ATP is hydrolyzed, the Cu(II) ions are bound to the nitrogen atoms of polyamine molecules. We did not detect any direct coordination of the N7 nitrogen atom of adenosine to Cu(II) ions. It means that the CuN7 interaction is an indirect type and can be due to noncovalent interplay including water molecule. EPR studies were performed at glassy state (77K) after a fast freezing both for binary and ternary systems. The glassy state EPR spectra do not reflect species identified in titration studies indicating significant effect of rapid temperature decrease on equilibrium of Cu(II) complexes. We propose the molecular structure of all the studied complexes at the glassy state deduced from EPR and optical spectroscopy results.

Climate change and the regulation of wood formation in trees by temperature

A better understanding of the influence of environmental conditions on wood formation should help to improve the radial growth of trees and to prepare for climate change. The cambial activity of trees is associated with seasonal cycles of activity and dormancy in temperate zones. The timing of cambial reactivation in early spring and dormancy in autumn plays an important role in determination of the cambial growth and the environmental adaptivity of temperate trees. This review focuses on the temperature regulation of the timing of cambial reactivation and xylem differentiation and highlights recent advances of bud growth in relation to cambial activity of temperate trees. In addition, we discuss relationships between the timing of cambial reactivation, start of xylem differentiation and changes in levels of storage materials to identify the source of the energy required for cell division and differentiation. We also present a summary of current understanding of the effects of rapid increases and decreases in temperature on cambial activity, by localized heating and cooling, respectively. Increases in temperature from late winter to early spring influence the physiological processes that are involved in the initiation of cambial reactivation and xylem differentiation both in localized heated stems and under natural conditions. Localized cooling has a direct effect on cell expansion, the thickening of walls of differentiating tracheids, and the rate of division of cambial cells. A rapid decrease in temperature of the stem might be the critical factor in the control of latewood formation and the cessation of cambial activity. Therefore, temperature is the main driver of cambial activity in temperate trees and trees are able to feel changes in temperature through the stem. The climate change might affect wood formation in trees.

Imaging the Yellow Sea Bottom Cold Water from multichannel seismic data

The Yellow Sea Bottom Cold Water (YSBCW) is a large cold water mass lying in the deep part of the Yellow Sea during the warm season. We acquired multichannel seismic (MCS) data using an air gun source to image the structure of the YSBCW. The MCS data recorded reflections from sea water. The recognition of these reflections was confirmed by finite-difference seismic modeling in the frequency-domain. The seismic section from MCS data enabled discrimination of water masses distinctly separated by reflecting horizons. The structure of the water masses is fairly consistent with temperature-depth variations obtained using expandable bathythermograph (XBT) casts. The YSBCW is imaged as the lowermost water mass, maximally 40 m thick, that extends as a lens-like form along the sea bottom under the warm mixed layer. The correlation of XBT measurements and the seismic section indicates a rapid decrease in temperature from around 11 to 8 °C in the uppermost part of the YSBCW. A transition zone between the mixed layer and the underlying YSBCW is also defined. This transition zone has fairly uniform thickness of 14–18 m and marks an interval of rapid temperature drop, indicating vigorous thermal mixing. Our study demonstrates that MCS profiling is a useful and reliable tool for imaging fine structures in the shallow Yellow Sea.

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.

Experimental investigation of quench and re-wetting temperatures of hot horizontal tubes well above the limiting temperature for solid–liquid contact

Quench cooling of a hot dry surface involves the rapid decrease in surface temperature resulting from bringing the hot surface into sudden contact with a coolant at a lower temperature. Quench temperature is the onset of the rapid decrease in surface temperature and corresponds to the onset of destabilization of a vapor film that exists between the hot surface and the coolant. Situations involving quench cooling are encountered in a number of postulated accidents in Canada Deuterium Uranium CANDU reactors, such as the quench of a hot calandria tube in certain Loss of Coolant Accidents LOCA. If the calandria tube temperature is not reduced by initiation of quench heat transfer, then this may lead to subsequent fuel channel failure and for this accident knowledge of quench heat transfer characteristics is of great importance. In this study, a Water Quench Facility WQF has been designed and built at the Thermal Processing Laboratory TPL at McMaster University and a series of experimental tests were carried out to investigate the quench of hot horizontal tubes using a vertical rectangular water multi-jet system. The tubes were heated to a temperature between 380 and 780°C then cooled to the jet temperature. The temperature variation with time in tube circumferential and axial directions was measured. The two-phase flow behavior and the propagation of the re-wetting front around and along the tubes were simultaneously observed using a high-speed camera. The effects of initial surface temperature, water subcooling (in the range 15–80°C) and jet velocity (in the range 0.15–1.60m/s) on the quench process were investigated. The quench and the re-wetting temperature (the temperature at which the liquid establishes wet contact with the solid) were found to greatly depend on water subcooling. One of the main findings in this study is the existence of a critical water subcooling range within which any small change in water subcooling has a considerable effect on both the quench and the re-wetting temperatures. Empirical correlations have been developed and provided good fit of the experimental data and agreed well with correlations developed by other researchers for curved surfaces. The quench temperature was found to decrease by increasing surface curvature and solid thermal conductivity. However, the re-wetting temperature is a weak function of both variables. Effect of spatial location on the surface of the tube was also studied. The stagnation point showed higher quench and re-wetting temperatures compared to other locations on the tube surface.