scholarly journals A new approach to precise mapping of local temperature fields in submicrometer aqueous volumes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexey M. Romshin ◽  
Vadim Zeeb ◽  
Artem K. Martyanov ◽  
Oleg S. Kudryavtsev ◽  
Dmitrii G. Pasternak ◽  
...  
Keyword(s):  
Thermodynamic System ◽  
Temperature Fields ◽  
Cell Physiology ◽  
New Approach ◽  
Submicron Scale ◽  
All Optical ◽  
High Gradients ◽  
Experimental Values ◽  
Paradigm Shifting ◽  
Closed Thermodynamic System

AbstractNanodiamonds hosting temperature-sensing centers constitute a closed thermodynamic system. Such a system prevents direct contact of the temperature sensors with the environment making it an ideal environmental insensitive nanosized thermometer. A new design of a nanodiamond thermometer, based on a 500-nm luminescent nanodiamond embedded into the inner channel of a glass submicron pipette is reported. All-optical detection of temperature, based on spectral changes of the emission of “silicon-vacancy” centers with temperature, is used. We demonstrate the applicability of the thermometric tool to the study of temperature distribution near a local heater, placed in an aqueous medium. The calculated and experimental values of temperatures are shown to coincide within measurement error at gradients up to 20 °C/μm. Until now, temperature measurements on the submicron scale at such high gradients have not been performed. The new thermometric tool opens up unique opportunities to answer the urgent paradigm-shifting questions of cell physiology thermodynamics.

scholarly journals A Software Architecture to Mimic a Ventricular Tachycardia in Intact Murine Hearts by Means of an All-Optical Platform

2019 ◽  
Vol 2 (1) ◽  
pp. 7 ◽  
Author(s):  
Francesco Giardini ◽  
Valentina Biasci ◽  
Marina Scardigli ◽  
Francesco S. Pavone ◽  
Gil Bub ◽  
...  
Keyword(s):  
Ventricular Tachycardia ◽  
Electrical Activity ◽  
Real Time ◽  
Temporal Resolution ◽  
Technical Note ◽  
High Temporal Resolution ◽  
Excitable Cells ◽  
New Approach ◽  
Cardiac Electrical Activity ◽  
All Optical

Optogenetics is an emerging method that uses light to manipulate electrical activity in excitable cells exploiting the interaction between light and light-sensitive depolarizing ion channels, such as channelrhodopsin-2 (ChR2). Initially used in the neuroscience, it has been adopted in cardiac research where the expression of ChR2 in cardiac preparations allows optical pacing, resynchronization and defibrillation. Recently, optogenetics has been leveraged to manipulate cardiac electrical activity in the intact heart in real-time. This new approach was applied to simulate a re-entrant circuit across the ventricle. In this technical note, we describe the development and the implementation of a new software package for real-time optogenetic intervention. The package consists of a single LabVIEW program that simultaneously captures images at very high frame rates and delivers precisely timed optogenetic stimuli based on the content of the images. The software implementation guarantees closed-loop optical manipulation at high temporal resolution by processing the raw data in workstation memory. We demonstrate that this strategy allows the simulation of a ventricular tachycardia with high stability and with a negligible loss of data with a temporal resolution of up to 1 ms.

On thermodynamics and the nature of the second law

1977 ◽  
Vol 357 (1690) ◽  
pp. 253-270 ◽  
Keyword(s):  
Mechanical Response ◽  
The Body ◽  
Temperature Fields ◽  
Second Law ◽  
Fading Memory ◽  
New Approach ◽  
Spatially Homogeneous ◽  
Dissipative Material ◽  
Point Of Departure ◽  
Homogeneous Temperature

The contents of this paper represent a new approach to continuum thermo­dynamics and are chiefly concerned with ( a ) a procedure for obtaining restrictions on constitutive equations, ( b ) an appropriate mathematical statement of the second law and ( c ) the nature of restrictions placed by the latter on thermo-mechanical behaviour of single phase continua. Our point of departure is the introduction of a balance of entropy and the use of the energy equation as an identity for all motions and all temperature distributions after the elimination of the external fields. This is in contrast to the approach adopted in most of the current literature on continuum ther­modynamics based on the use of the Clausius-Duhem inequality. In order to gain some insight into the nature of our procedure we first study the case of an elastic material, which includes that of an ideal fluid as a special case, before the consideration of the second law. We then go on to postu­late an inequality which reflects the fact that for every process associated with a dissipative material, a part of the mechanical work is always con­verted into heat and this cannot be withdrawn from the medium as mech­anical work. The restriction on the heat conduction vector is considered separately and is confined to equilibrium cases in which heat flow is steady. A restriction is also obtained for the internal energy when the body is in mechanical equilibrium subjected to spatially homogeneous temperature fields. Using the above approach, next we study the nature of thermodynamic restrictions on the thermo-mechanical response of a viscous fluid and simple materials with fading memory. A drawback to the Clausius-Duhem inequality is discussed by means of an example. For a class of rigid heat conductors in thermal equilibrium, the Clausius-Duhem inequality requires that if heat is added to the medium, the resulting spatially homogeneous temperature of the conductor decreases . Moreover, the in­-equality denies the possibility of propagation of heat in the conductor as a thermal wave with finite speed. The inequalities proposed in this paper do not suffer from these shortcomings.

Chemical Reactions at the in Vacuo Au/Inp Interface

1986 ◽  
Vol 83 ◽  
Author(s):  
R. Stanley Williams ◽  
C. Thomas Tsai ◽  
Eun-Hee Cirlin
Keyword(s):  
Intermetallic Compound ◽  
Atmospheric Pressure ◽  
High Vacuum ◽  
Thermodynamic System ◽  
External Pressure ◽  
Ultra High Vacuum ◽  
Reaction Products ◽  
Inp Substrate ◽  
Major Reaction ◽  
Closed Thermodynamic System

ABSTRACTThe reaction between a Au film and an Inp substrate occurs much more readily in vacuo than under an external pressure of an inert ga. At atmospheric pressure, the compounds Au2P3 and the γ intermetallic compound (at times designated Au7In3, Au9In4, or Au2In) are formed at 450 °C and remain fairly stable even when annealed at 500°C for hours. Under ultra-high vacuum conditions, phosphorous readily escapes from the film when a sample is annealed at 300°C for 15 minutes, and the major reaction products are the ψ phase (Au3In2) and another intermetallic compound that is probably AuIn. The presence of an inert gas creates a kinetic barrier for the escape of phosphorous from the surface, and thus Au/InP behaves more like a closed thermodynamic system under pressure than in a vacuum.

scholarly journals Development methodology of determinating residual carrying capacity of reinforced concrete beams with damages tensile reinforcement which occurred during loading

2021 ◽  
Vol 4 (7(112)) ◽  
pp. 6-17
Author(s):  
Pavlo Vegera ◽  
Rostyslav Vashkevych ◽  
Yaroslav Blikharskyy ◽  
Roman Khmil
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Concrete Beams ◽  
Variable Parameter ◽  
Load Level ◽  
Reinforced Concrete Beams ◽  
New Approach ◽  
Development Methodology ◽  
Experimental Values ◽  
Strain Model

This paper reports the improved and verified procedure for calculating reinforced concrete beams affected by damage to stretched reinforcement when loaded. The main results from testing the reinforced concrete beams with damage in the stretched zone in the form of one hole in the reinforcement in the middle of the beam are given. The variable parameter of the study was the level of load resulting in the damage. It acquired values of 0, 30 %, 50 %, 70 % of the bearing capacity of control undamaged samples. Overall, the results of testing 12 samples are given. A new procedure has been proposed for taking into consideration changes in the mechanical characteristics of stretched reinforcement arising from its damage. This makes it possible to more accurately establish the bearing capacity of reinforced concrete bended elements affected by damage to their reinforcement during operation. The analysis of the calculation, compared with experimental quantities, led to a conclusion that the strain model could determine when the bearing capacity of reinforced concrete beams without damage and with damage to working reinforcement is exhausted. Based on the improved algorithm, the principle of using a strain model was proposed to establish when the bearing capacity of damaged samples, taking into consideration the effect of the load level, is exhausted. The theoretical estimation, considering when the bearing capacity is exhausted, showed results that are 3...21 % less than the experimental values, which ensures reliability of calculation of such structures. The proposed calculation provides a new approach to determining the bearing capacity of reinforced concrete beams damaged during operation. That, in turn, makes it possible to more accurately determine the residual bearing capacity of structures and increases the safety of their operation.

scholarly journals Ultrafast defect dynamics: A new approach to all optical broadband switching employing amorphous selenium thin films

AIP Advances ◽  
2015 ◽  
Vol 5 (7) ◽  
pp. 077164 ◽  
Author(s):  
Rituraj Sharma ◽  
Kiran Prasai ◽  
D. A. Drabold ◽  
K. V. Adarsh
Keyword(s):  
Thin Films ◽  
Amorphous Selenium ◽  
New Approach ◽  
All Optical

scholarly journals Gas-Vapor Mixture Temperature in the Near-Surface Layer of a Rapidly-Evaporating Water Droplet

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 803
Author(s):  
Antonov ◽  
Volkov ◽  
Strizhak
Keyword(s):  
High Temperature ◽  
Temperature Fields ◽  
Vapor Mixture ◽  
Water Droplets ◽  
Unsteady Temperature ◽  
Near Surface ◽  
Planar Laser ◽  
Steady Temperature Field ◽  
Experimental Values ◽  
High Temperature Gas

Mathematical modeling of the heat and mass transfer processes in the evaporating droplet–high-temperature gas medium system is difficult due to the need to describe the dynamics of the formation of the quasi-steady temperature field of evaporating droplets, as well as of a gas-vapor buffer layer around them and in their trace during evaporation in high-temperature gas flows. We used planar laser-induced fluorescence (PLIF) and laser-induced phosphorescence (LIP). The experiments were conducted with water droplets (initial radius 1–2 mm) heated in a hot air flow (temperature 20–500 °С, velocity 0.5–6 m/s). Unsteady temperature fields of water droplets and the gas-vapor mixture around them were recorded. High inhomogeneity of temperature fields under study has been validated. To determine the temperature in the so called dead zones, we solved the problem of heat transfer, in which the temperature in boundary conditions was set on the basis of experimental values.

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