Cold Bath Research Articles

Efficiency of a cyclic quantum heat engine with finite-size baths.

In this paper we investigate the relationship between the efficiency of a cyclic quantum heat engine with the Hilbert space dimension of the thermal baths. By means of a general inequality, we show that the Carnot efficiency can be obtained only when both the hot and cold baths are infinitely large. By further introducing a specific model where the baths are constituted of ensembles of finite-dimensional particles, we further demonstrate the relationship between the engine's power and efficiency, with the dimension of the working substance and the bath particles.

Quantized refrigerator for an atomic cloud

We propose to implement a quantized thermal machine based on a mixture of two atomic species. One atomic species implements the working medium and the other implements two (cold and hot) baths. We show that such a setup can be employed for the refrigeration of a large bosonic cloud starting above and ending below the condensation threshold. We analyze its operation in a regime conforming to the quantized Otto cycle and discuss the prospects for continuous-cycle operation, addressing the experimental as well as theoretical limitations. Beyond its applicative significance, this setup has a potential for the study of fundamental questions of quantum thermodynamics.

Mpemba Index and Anomalous Relaxation

The Mpemba effect is a counter-intuitive relaxation phenomenon, where a system prepared at a hot temperature cools down faster than an identical system initiated at a cold temperature when both are quenched to an even colder bath. Such non-monotonic relaxations were observed in various systems, including water, magnetic alloys, polymers, and driven granular gases. We analyze the Mpemba effect in Markovian dynamics and discover that a stronger version of the effect often exists for a carefully chosen set of initial temperatures. In this \emph{strong Mpemba effect}, the relaxation time jumps to a smaller value leading to exponentially faster equilibration dynamics. The number of such special initial temperatures defines the \emph{Mpemba index}, whose parity is a topological property of the system. To demonstrate these concepts, we first analyze the different types of Mpemba relaxations in the mean field anti-ferromagnet Ising model, which demonstrates a surprisingly rich Mpemba phase diagram. Moreover, we show that the strong effect survives the thermodynamic limit and that it is tightly connected with thermal overshoot -- in the relaxation process, the temperature of the relaxing system can decay non-monotonically as a function of time. Using the parity of the Mpemba index, we then study the occurrence of the strong Mpemba effect in a large class of thermal quench processes and show that it happens with non-zero probability even in the thermodynamic limit. This is done by introducing the \emph{isotropic} model for which we obtain analytical lower bound estimates for the probability of the strong Mpemba effects. Consequently, we expect that such exponentially faster relaxations can be observed experimentally in a wide variety of systems.

Femtosecond Laser-Induced Thermal Transport in Silicon with Liquid Cooling Bath.

Nanostructured regular patterns on silicon surface are made by using femtosecond laser irradiations. This is a novel method that can modify the surface morphology of any large material in an easy, fast, and low-cost way. We irradiate a solid surface with a 400-nm double frequency beam from an 800-nm femtosecond laser, while the solid surface is submerged in a liquid or exposed in air. From the study of multiple-pulses and single-pulse irradiations on silicon, we find the morphologies of nanospikes and capillary waves to follow the same distribution and periodicity. Thermal transport near the solid surface plays an important role in the formation of patterns; a simulation was done to fully understand the mechanism of the pattern formation in single pulse irradiation. The theoretical models include a femtosecond laser pulse function, a two-temperature model (2-T model), and an estimation of interface thermal coupling. The evolution of lattice temperature over time will be calculated first without liquid cooling and then with liquid cooling, which has not been well considered in previous theoretical papers. The lifetime of the capillary wave is found to be longer than the solidification time of the molten silicon only when water cooling is introduced. This allows the capillary wave to be frozen and leaves interesting concentric rings on the silicon surface. The regular nanospikes generated on the silicon surface result from the overlapping capillary waves.

Perception and Management of Fever in Children, by Mothers in Port Harcourt Nigeria

To determine mother’s perception and management of fever in their children. It was a descriptive cross-sectional study, carried out at the children outpatient clinic of the department of Paediatrics, University of Port Harcourt Teaching Hospital, over a one-year period, January to December, 2012. Every mother who presented with her child to the children outpatient clinic was recruited and interviewed using a structured questionnaire after obtaining written informed consent, as they presented their children to the children outpatient clinic of the University of Port Harcourt Teaching Hospital until we recruited 324mothers, whose children aged between 0-16 years into the study. A little over half of these mothers had completed secondary education. The thermometer was used by 209(64.50%) mothers and the preferred route was by mouth 135(41.67%). 175(54.01%) mothers reported temperature <35ºC as fever. 49.07% of the mothers were worried about the consequences of the fever. 43(13.3%) would give paracetamol. 24(7.4%) would tepid sponge. 15(4.6%) would give a cold bath. 6(1.9%) expose the child to air with reduced clothing. 4(1.2%), wrap the child with warm and thick cloth. 2(0.6%) gave antibiotics. 11 (3.4%) gave antimalaria. 6(1.9%) gave teething drugs. 1 (0.3%) gave nothing. Most mothers got their information on knowledge of fever management from doctors and nurses-164(50.62%). Paracetamol was the most commonly used drug by mothers for the treatment of fever at home-217 (67%). 87(26.852%) would take the child to hospital if fever persisted. This study found a significant association between using physical methods such as giving cold bath to reduce fever, and tepid sponging to reduce fever with no formal education P < 0.0001 and P< 0.0165 respectively. Data was analyzed using Epi-info version 7. Mothers awareness of fever in Port Harcourt is low and Paracetamol is commonly given to children with fever.

The application of zinc oxide layer as ethylene sensor

As an emerging n-type semiconductor, ZnO has been widely applied in sensor area. In this study, we prepared an ethylene sensor using ZnO layer on FTO glass substrate. The seed layer was deposited using simple electrodeposition method using voltage of -1.1 V for 2 hours in cold bath (6°C). The ZnO layer was further grown using CBD technique at 90°C for 2 hours. In order to observe the effect of structural manipulation on the sensor performance, some of the ZnO layer samples were undergoing hydrothermal treatment at 100ºC for 1 hour under 1 bar N2 gas. After annealing process, all ZnO layers were exposed with 50 ppm ethylene gas in closed chamber. Based on the results, it is shown that the optimum ZnO layer has been successfully identified the ethylene gas in concentration of 50 ppm, with response value of 2.40% at 200°C.

Review: Architectural Invention in Renaissance Rome: Artists, Humanists, and the Planning of Raphael's Villa Madama, by Yvonne Elet

Yvonne Elet Architectural Invention in Renaissance Rome: Artists, Humanists, and the Planning of Raphael's Villa Madama Cambridge: Cambridge University Press, 2017, 360 pp., 19 color and 98 b/w illus. $120 (cloth), ISBN 9781107130524 Standing majestically on Monte Mario just north of Rome overlooking the Tiber and the Milvian Bridge, the unfinished Villa Madama (1518) is one of the most celebrated and innovative buildings of its time. As a locus amoenus for Cardinal Giulio de’ Medici and his friends, and as a setting used by Pope Leo X to accommodate foreign dignitaries when they visited the city, the villa represented an attempt to create an environment in which visitors could imagine themselves transported back to Roman antiquity. Its spaces were intended to seem ancient in name, form, and function. It was to have had a semicircular theater cut into the hillside; a hippodrome; a set of cold, warm, and hot baths; and a circular courtyard emulating one of Pliny the Younger's villas. The forms, materials, and techniques adopted during the villa's construction were radically antique too. The stucco duro decoration of the garden loggia was created using an ancient technique largely reinvented by Raphael's workshop, and the various brickwork techniques used throughout the complex closely reflected ancient precedents. These features have all been explored exhaustively in the existing literature. What the literature has not addressed, …

Can soot primary particle size distributions be determined using laser-induced incandescence?

Soot from combustion processes often takes the form of fractal-like aggregates, assembled of primary particles, both of which obey polydisperse size distributions. In this work, the possibility of determining the primary particle size distribution through time-resolved laser-induced incandescence (TiRe-LII) under the influence of thermal shielding of polydispersely distributed aggregates is critically investigated for two typical measurement situations: in-flame measurements at high temperature and a soot-laden aerosol at room temperature. The uncertainty attached to the quantities is evaluated through Bayesian inference. We show how different kinds of prior knowledge concerning the aggregation state of the aerosol affect the uncertainties of the recovered size distribution parameters of the primary particles. To obtain reliable estimates for the primary particle size distribution parameters, specific information about the aggregate size distribution is required. This is especially the case for cold bath gases, where thermal shielding has a large effect. Furthermore, it is crucial to use the full duration of the usable LII signal trace to recover the width of the size distribution with small uncertainties. The uncertainty attached to TiRe-LII inferred primary particle size parameters becomes considerably larger when additional model parameters are considered.

Superior compound coatings prepared by low-temperature vanadium-nitrocarburizing duplex treatment

Superior compound coatings were prepared on CK45 steel surface by vanadium-nitrocarburizing duplex treatment in low-temperature salt bath. In this study, the microhardness, the phase constitution and the compositional distribution in the coatings prepared under different conditions were systematically characterized. The results indicated that the reactions among activated vanadium, carbon and nitrogen atoms occurred on the steel surface, leading to the formation of compound coatings composed of outermost and compound layers. The mechanism for the formation of compound layer as well as the growth kinetics of the layer was also discussed. Upon the duplex treatment, the wear and corrosion resistances of steel surface were significantly improved. It was found that the growth kinetics of compound layer obeyed the parabolic law, with the activation energy of 122.82 kJ·mol−1.

Study of wax deposition law by cold finger device

Wax deposits in oil pipelines can reduce the effective inner diameter of such pipelines, which may lead to pipeline blockage accidents. In this study, a cold finger experimental device was constructed, and eight groups of experimental scenarios under cold flow conditions were performed in accordance with field conditions. The effects of deposition time and cold and hot bath temperatures on wax deposition were investigated. Results show that when the cold bath temperature remains unchanged, and only the hot bath temperature increases, the deposition quality and rate of mixed waxy crude oil will initially decrease and then increase. During this period, the temperature that corresponds to the maximum deposition mass is the starting point of the wax precipitation peak.

A low temperature electroless nickel plating chemistry

An acidic electroless nickel bath was formulated to plate high phosphorus nickel alloy at a low temperature from 45 to 50 °C. The low temperature EN bath, containing nickel ions, reducing agent, complexing agent, stabilizer, and accelerator, was optimized in composition to deposit high phosphorus nickel alloy (>11 wt% P) at temperature <50 °C which is not achievable by either commercial alkaline EN baths or commercial acidic EN baths at such a low plating temperature. The successful electroless forming of an EN film micro sieve based on positive photoresist patterns demonstrated that the low temperature bath is suitable for high phosphorus EN plating with temperature sensitive polymer materials.

Thermal power of heat flow through a qubit.

In this paper we consider the thermal power of a heat flow through a qubit between two baths. The baths are modeled as a set of harmonic oscillators initially at equilibrium, at two temperatures. Heat is defined as the change of energy of the cold bath, and thermal power is defined as expected heat per unit time, in the long-time limit. The qubit and the baths interact as in the spin-boson model, i.e., through qubit operator σ_{z}. We compute thermal power in an approximation analogous to a "noninteracting blip" (NIBA) and express it in the polaron picture as products of correlation functions of the two baths, and a time derivative of a correlation function of the cold bath. In the limit of weak interaction we recover known results in terms of a sum of correlation functions of the two baths, a correlation functions of the cold bath only, and the energy split.

Nitrite-Induced Activation of Iodate into Molecular Iodine in Frozen Solution.

A new mechanism for the abiotic production of molecular iodine (I2) from iodate (IO3-), which is the most abundant iodine species, in dark conditions was identified and investigated. The production of I2 in aqueous solution containing IO3- and nitrite (NO2-) at 25 °C was negligible. However, the redox chemical reaction between IO3- and NO2- rapidly proceeded in frozen solution at -20 °C, which resulted in the production of I2, I-, and NO3-. The rapid redox chemical reaction between IO3- and NO2- in frozen solution is ascribed to the accumulation of IO3-, NO2-, and protons in the liquid regions between ice crystals during freezing (freeze concentration effect). This freeze concentration effect was verified by confocal Raman microscopy for the solute concentration and UV-visible absorption spectroscopy with cresol red (acid-base indicator) for the proton concentration. The freezing-induced production of I2 in the presence of IO3- and NO2- was observed under various conditions, which suggests this abiotic process for I2 production is not restricted to a specific region and occurs in many cold regions. NO2--induced activation of IO3- to I2 in frozen solution may help explain why the measured values of iodine are larger than the modeled values in some polar areas.

(205) Cellular Mechanisms Underlying Keratinocyte Cold Responses and Subsequent Modulation of Sensory Neuron Thermal Activity

Thermosensation is a critical process through which organisms detect temperature changes within the body and local environment. Convention proposes that thermosensation, and general somatosensation, is mediated exclusively by sensory neurons. Recent publications challenge this idea by describing the role that epidermal cells play in the detection and transmission of mechanical stimuli. Keratinocytes, which constitute 95% of the cells in the epidermis, are depolarized upon mechanical stimulation and release ATP which then modulates sensory neuron responses to mechanical stimuli via P2X4 receptors (Moehring, eLife, 2018). The ability of keratinocytes to respond to cold temperature, another omnipresent sensation, remains unknown. To answer this question, archaerhodopsin-3, an inhibitory opsin, was expressed in epidermal cells. Optogenetic inhibition of epidermal cells significantly decreased cold sensitivity in naive mice; paw withdrawal latencies to a dry ice stimulus were increased by ∼35%. To dissect the keratinocyte signaling pathways mediating the response to cold, calcium imaging was employed. Primary keratinocytes from mouse glabrous skin exhibited rapid and robust responses to a ramp of decreasing bath temperature; of 600+ cells tested, 100% were sensitive to cold stimulation. Cold responses were abolished when extracellular calcium or sodium were omitted from buffer. To specifically assess which cold-sensitive ion channels initiate and sustain this response, various pharmacological agents were included in the cold bath. Finally, the relevance of keratinocyte ATP to sensory neuron P2X4 signaling was assessed with regards to cold sensation. Local hydrolysis of ATP increased paw withdrawal latencies to cold stimuli similar to optogenetic inhibition of keratinocytes. Cell sniff assays confirmed the ability of keratinocytes to release ATP upon cold stimulation. P2X4 sensory neuron knockout mice were also significantly less sensitive to plantar cold stimulation. Collectively, these experiments illustrate the previously unknown ability of keratinocytes to respond to cold and alter downstream sensory neuron responses to cold stimuli.

(169) Comparison of Temporal Stability of Conditioned Pain Modulation and Temporal Summation of Pain in Healthy Older and Younger Adults

The temporal stability (test-retest reliability) of temporal summation of pain (TS) and conditioned pain modulation (CPM) has yet to be established in healthy older adults. The current study intended to compare the temporal stability of TS and CPM in healthy older and younger adults, as well as investigate factors that might impact TS and CPM stability. In a test-retest study, 40 healthy older adults and 18 healthy younger adults completed two sessions of quantitative sensory testing within a 2-week period that included: 1) TS of heat pain, 2) TS of mechanical pain, 3) CPM with pressure pain thresholds (CPM-PPT) and suprathreshold heat pain (CPM-Heat) as test stimuli and a cold water bath as conditioning stimulus. During each session participants completed the pain catastrophizing scale and the State Trait Anxiety Scale – state version. The relative stability (Interclass correlation coefficients: ICCs) and intra-individual stability coefficients (ISC) were examined for each variable. Bivariate correlations examined the association of psychological variables and age with the ISCs of TS and CPM. Younger adults showed good to excellent stability for TS (ICC's: 0.64-0.89), except for mechanical TS on the hand (ICC: 0.34). Older adults showed moderate to good stability for TS (ICC's: 0.48-0.79). Stability of CPM-PPT was poor for younger and older adults, whereas stability of CPM-Heat was good for younger adults but poor for older adults. Correlational analyses indicated greater ISC's for CPM were associated with greater stability of the pre-test stimuli. State anxiety was significantly associated with stability of CPM-Heat and TS. These findings suggest that 1) TS and CPM may be more reliable in younger compared to older adults and 2) state anxiety is an important factor influencing the stability of CPM and TS in healthy adults. This study was funded by the IUPUI Developing Diverse Researchers with Investigative Experience Grant.

Anesthetic MS-222 eliminates nerve and muscle activity in frogs used for physiology teaching laboratories

Frogs are routinely used in physiology teaching laboratories to demonstrate important physiological processes. There have been recent directives that promote the use of the anesthetic MS-222 (tricaine methanesulfonate), rather than lowering body temperature with a cold water bath to prepare reptiles and amphibians for physiological experiments or euthanasia. Indeed, the most recent edition of the American Veterinary Medical Association (AVMA) Guidelines for the Euthanasia of Animals proclaims that chilling in water is not an appropriate method and advocates for the usage of MS-222 or other anesthetics. However, prominent researchers have responded to this position by highlighting evidence that cooling ectothermic vertebrates is, in fact, an effective and appropriate method. Furthermore, MS-222 is a known voltage-gated Na+ channel blocker, and this anesthetic's impact on the physiology of excitable tissues suggests that its use might be incompatible with experiments on nerve and muscle tissues. In the present study, I examined the effects of MS-222 at a concentration of 1.5 g/l on nerve, skeletal muscle, and cardiac muscle physiology of frogs. I found that immersion of frogs in this anesthetic blocked basic nerve and muscle physiology, making the frogs unsuitable for laboratory experiments. Applying MS-222 directly to the sciatic nerve dramatically blocked normal excitation-contraction coupling in skeletal muscle preparations, and direct application to the heart caused the organs to stop contracting. Based on these results, I conclude that MS-222 at the concentration studied may be incompatible with physiological preparations that rely on electrically excitable tissues for their normal function. Physiology educators who must use MS-222 with frogs should empirically determine an appropriate dosage and recovery time before using the anesthetic in the teaching laboratory.

Non-equilibrium molecular dynamics study on radial thermal conductivity and thermal rectification of graphene

ABSTRACTIn the present study, the radial thermal rectification and thermal conductivity of the graphene were investigated by non-equilibrium molecular dynamics simulation and then corrected by quantum correction to make it closer to the fact. The Optimised three-body Tersoff potential is employed in order to simulate the interactions between the carbon atoms in the graphene sheet. A circular region in the centre and the one at the graphene edge are selected as hot and cold bath to generate radial temperature gradient. It is observed that the heat current passes through radially inward direction than outward with the same temperature gradient and hence there is a radial thermal rectification in graphene. Also, temperature distribution and heat flux are theoretically introduced as a function of distance from the graphene centre and then it is confirmed by the molecular dynamics simulation data. Finally, the influence of temperature gradient and size of graphene on radial thermal rectification and the impact of size on the radial thermal conductivity is investigated.

Detectability of the degree of freeze damage in meat depends on analytic-tool selection

Novel freezing solutions are constantly being developed to reduce quality loss in meat production chains. However, there is limited focus on identifying the sensitive analytical tools needed to directly validate product changes that result from potential improvements in freezing technology. To benchmark analytical tools relevant to meat research and production, we froze pork samples using traditional (−25 °C, −35 °C) and cryogenic freezing (−196 °C). Three classes of analyses were tested for their capacity to separate different freeze treatments: thaw loss testing, bioelectrical spectroscopy (nuclear magnetic resonance, microwave, bioimpedance) and low-temperature microscopy (cryo-SEM). A general effect of freeze treatment was detected with all bioelectrical methods. Yet, only cryo-SEM resolved quality differences between all freeze treatments, not only between cryogenic and traditional freezing. The detection sensitivity with cryo-SEM may be explained by testing meat directly in the frozen state without prior defrosting. We discuss advantages, shortcomings and cost factors in using analytical tools for quality monitoring in the meat sector.

Numerical analysis of a closed loop two-phase thermosyphon under states of single-phase, two-phase and supercritical

Closed loop two-phase thermosyphon is an effective heat transfer device, of which the research is necessary to clarify the heat transfer and fluid flow mechanism. Numerical analysis was carried out in the article with one-dimensional model. The model was based on mass, momentum and energy conversation equations, solved by iterative method. Single-phase and two-phase flow were simulated, besides supercritical flow. Experimental data was used in the validation of the model with the error less than ±10%. The axial evolution of several parameters, namely pressure, enthalpy, void fraction, vapor quality and heat transfer coefficient in the loop, were presented firstly. Then the effects of pipe diameter, filling ratio, height difference, heat load, cold bath temperature and fluid type on the closed loop two-phase thermosyphon were investigated. Large pipe diameter and medium filling ratio led to low thermal resistance. The thermal resistance decreased with the increase of height difference firstly, and then increased at large height differences. Larger heat load led to higher mass flux, as well as larger subcooled or superheated region. Vapor quality at the outlet of evaporator increased with the increase in cold bath temperature, leading to low thermal resistance. Fluids with low viscosity and large density difference between liquid and vapor phase were suggested for favorable heat transfer performance. It was also concluded that thermal resistance increased sharply when supercritical phenomenon occurred due to the disappearance of two-phase region.

Observational Study of Frequent Degenerative Low Back Pain Syndromes on Patients Under Balneal Treatment

Abstract Degenerative low back pain is one of the most important causes of disability worldwide, and it also has a negative impact on the economy, due to the high cost of medical care required for this pathology. It has an increased prevalence among the population, between 80-85%, it affects population between 45 and 65 years old, and the most frequent cause is the mechanical one, with degenerative syndromes on the first place. Balneal treatment is a complex treatment with multiple benefits for patients with degenerative low back pain syndromes, and in the recent years this topic is intensely studied due to its benefits, as well as the increased addressability of the patients for this type of treatment. Our study evaluated 99 patients with low back pain divided into 2 groups of patients admitted for 2 weeks to Balneal and Rehabilitation Sanatorium of Techirghiol, who performed balneal treatment with hot mud baths and cold mud baths, but also classic rehabilitation treatment (electrotherapy, masotherapy, kinetotherapy, thermotherapy). The aim of the study was to evaluate the characteristics of degenerative low back pain syndromes on patients under balneal treatment, and for the patients from our study the most frequent pathology was Spondilosis, female patients was predominantly affected than male patients, with high education level and from urban residence.