scholarly journals In situ measurements of intracellular thermal conductivity using heater-thermometer hybrid diamond nanosensors

2021 ◽  
Vol 7 (3) ◽  
pp. eabd7888
Author(s):  
Shingo Sotoma ◽  
Chongxia Zhong ◽  
James Chen Yong Kah ◽  
Hayato Yamashita ◽  
Taras Plakhotnik ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Dissipation ◽  
Transient Temperature ◽  
Mean Values ◽  
A Cell ◽  
The Mean ◽  
Dissipation Processes ◽  
Mcf 7

Understanding heat dissipation processes at nanoscale during cellular thermogenesis is essential to clarify the relationships between the heat and biological processes in cells and organisms. A key parameter determining the heat flux inside a cell is the local thermal conductivity, a factor poorly investigated both experimentally and theoretically. Here, using a nanoheater/nanothermometer hybrid made of a polydopamine encapsulating a fluorescent nanodiamond, we measured the intracellular thermal conductivities of HeLa and MCF-7 cells with a spatial resolution of about 200 nm. The mean values determined in these two cell lines are both 0.11 ± 0.04 W m−1 K−1, which is significantly smaller than that of water. Bayesian analysis of the data suggests there is a variation of the thermal conductivity within a cell. These results make the biological impact of transient temperature spikes in a cell much more feasible, and suggest that cells may use heat flux for short-distance thermal signaling.

scholarly journals In situ measurement of intracellular thermal conductivity using heater-thermometer hybrid diamond nanosensor

2020 ◽  
Author(s):  
Shingo Sotoma ◽  
Chongxia Zhong ◽  
James Chen Yong Kah ◽  
Hayato Yamashita ◽  
Taras Plakhotnik ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Dissipation ◽  
Mean Value ◽  
Biological Processes ◽  
A Cell ◽  
First Time ◽  
Dissipation Processes ◽  
Key Parameter

AbstractUnderstanding heat dissipation processes at nanoscale during cellular thermogenesis is essential to clarify the relationships between the heat and biological processes in cells and organisms. A key parameter determining the heat flux inside a cell is the local thermal conductivity, a factor poorly investigated both experimentally and theoretically. Here, using a nanoheater/nanothermometer hybrid based on a polydopamine shell encapsulating a fluorescent diamond nanocrystal, we measured the intracellular thermal conductivity of HeLa cell with a spatial resolution of about 200 nm. Its mean value of 0.11 Wm-1K-1 determined for the first time is significantly smaller than that of water. Bayesian analysis of the data strongly supports the existence of variation of the intracellular thermal conductivity of about 40%. These results present a major milestone towards understanding the intracellular heat transfer phenomena at nanoscale.

In situ thermal-conductivity measurements and morphological characterization of intumescent coatings for fire protection

2018 ◽  
Vol 36 (5) ◽  
pp. 419-437 ◽  
Author(s):  
Jiyuan Kang ◽  
Fumiaki Takahashi ◽  
James S T’ien
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Fire Protection ◽  
Heat Fluxes ◽  
Loss Cone ◽  
Char Layer ◽  
Intumescent Coatings ◽  
Apparent Thermal Conductivity ◽  
Initial Coating

Thermal insulating performance and char-layer properties have been studied for water-based intumescent coatings for structural steel fire protection using a new laboratory-scale mass-loss cone apparatus. A specimen (100 × 100 mm mild steel plate; the initial coating thickness: 0.3–2.0 mm) is placed horizontally and exposed to a constant incident radiant heat flux (25, 50, or 75 kW/m2). The apparent thermal conductivity of the expanding char layer is determined in situ based on real-time measurements of the temperature distribution in the char layer and the heat flux transmitted through the char layer. Three-dimensional morphological observations of the expanded char layer are made using a computed tomographic–based analytical method. The vertical variation of the porosity of the expanded char layer is measured. The measured heat-blocking efficiency is correlated strongly with the incident heat flux, which increases the expanded char-layer thickness, and porosity for sufficiently large initial coating thicknesses (>0.76 mm). For a thin coating (0.30 mm), violent off-gassing disrupts the intumescing processes to form a consistent char layer after abrupt exposure to higher incident heat fluxes, thus resulting in lower heat-blocking efficiency. Therefore, the product application thickness must exceed a proper threshold value to ensure an adequate thermal insulation performance.

scholarly journals Vectors of subsurface stormflow in a layered hillslope during runoff initiation

2006 ◽  
Vol 10 (3) ◽  
pp. 309-320 ◽  
Author(s):  
M. Retter ◽  
P. Kienzler ◽  
P. F. Germann
Keyword(s):  
Three Dimensional ◽  
Volume Flux ◽  
Wetting Front ◽  
Experimental Assessment ◽  
Mean Values ◽  
Top Soil ◽  
Wave Guides ◽  
The Mean ◽  
Vector Approach

Abstract. The focus is the experimental assessment of in-situ flow vectors in a hillslope soil. We selected a 100 m2 trenched hillslope study site. During prescribed sprinkling an obliquely installed TDR wave-guide provides for the velocity of the wetting front in its direction. A triplet of wave-guides mounted along the sides of an hypothetical tetrahedron, with its peak pointing down, produces a three-dimensional vector of the wetting front. The method is based on the passing of wetting fronts. We analysed 34 vectors along the hillslope at distributed locations and at soil depths from 11 cm (representing top soil) to 40 cm (close to bedrock interface). The mean values resulted as follows vx=16.1 mm min-1, vy=-0.2 mm min-1, and vz=11.9 mm min-1. The velocity vectors of the wetting fronts were generally gravity dominated and downslope orientated. Downslope direction (x-axis) dominated close to bedrock, whereas no preference between vertical and downslope direction was found in vectors close to the surface. The velocities along the contours (y-axis) varied widely. The Kruskal-Wallis tests indicated that the different upslope sprinkling areas had no influence on the orientation of the vectors. Vectors of volume flux density were also calculated for each triplet. The lateral velocities of the vector approach are compared with subsurface stromflow collected at the downhill end of the slope. Velocities were 25-140 times slower than lateral saturated tracer movements on top of the bedrock. Beside other points, we conclude that this method is restricted to non-complex substrate (skeleton or portion of big stones).

scholarly journals Tuning the Anisotropic Thermal Transport in {110}-Silicon Membranes with Surface Resonances

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 123
Author(s):  
Keqiang Li ◽  
Yajuan Cheng ◽  
Maofeng Dou ◽  
Wang Zeng ◽  
Sebastian Volz ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Heat Dissipation ◽  
Mean Free Path ◽  
Dynamic Simulations ◽  
Resonant Structures ◽  
Thermoelectric Energy ◽  
Thin Membranes ◽  
The Mean ◽  
Equilibrium Molecular Dynamic

Understanding the thermal transport in nanostructures has important applications in fields such as thermoelectric energy conversion, novel computing and heat dissipation. Using non-homogeneous equilibrium molecular dynamic simulations, we studied the thermal transport in pristine and resonant Si membranes bounded with {110} facets. The break of symmetry by surfaces led to the anisotropic thermal transport with the thermal conductivity along the [110]-direction to be 1.78 times larger than that along the [100]-direction in the pristine structure. In the pristine membranes, the mean free path of phonons along both the [100]- and [110]-directions could reach up to ∼100 µm. Such modes with ultra-long MFP could be effectively hindered by surface resonant pillars. As a result, the thermal conductivity was significantly reduced in resonant structures, with 87.0% and 80.8% reductions along the [110]- and [100]-directions, respectively. The thermal transport anisotropy was also reduced, with the ratio κ110/κ100 decreasing to 1.23. For both the pristine and resonant membranes, the thermal transport was mainly conducted by the in-plane modes. The current work could provide further insights in understanding the thermal transport in thin membranes and resonant structures.

One-pot in situ synthesis of CsPbX3@h-BN (X = Cl, Br, I) nanosheet composites with superior thermal stability for white LEDs

2019 ◽  
Vol 7 (14) ◽  
pp. 4038-4042 ◽  
Author(s):  
Lei Qiu ◽  
Jiarui Hao ◽  
Yuxin Feng ◽  
Xingyu Qu ◽  
Guogang Li ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Heat Dissipation ◽  
In Situ Synthesis ◽  
One Pot ◽  
White Leds ◽  
Synthesis Strategy ◽  
Dissipation Mechanism ◽  
Enhanced Thermal Conductivity

Highly thermally and environmentally stable CsPbX3@h-BN composites are constructed via a simple one-pot in situ synthesis strategy, and the corresponding heat dissipation mechanism is proposed based on the enhanced thermal conductivity.

Research of Relations between Thermodynamic Quantities of Building Materials in Connection with Heat Dissipation

2015 ◽  
Vol 244 ◽  
pp. 48-53
Author(s):  
Milena Kušnerová ◽  
Jan Valíček ◽  
Vojtěch Václavík ◽  
Marta Harničárová ◽  
Lukáš Gola
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Capacity ◽  
Dissipation Rate ◽  
Building Materials ◽  
Material Parameter ◽  
Heat Dissipation ◽  
Temporal Change ◽  
Point Of View ◽  
Physical Point

This paper proposes the evaluation of material coefficient of heat dissipation rate for building materials, in particular using partial entropies, a temporal change in entropy upon heating a sample of a studied material and a temporal change in entropy upon overheating a sample of a studied material, in order to evaluate the rate of heat dissipation on samples of building materials with thermal insulating properties. From a physical point of view, the material parameter “specific heat capacity” generally refers to the ability of material to “conceive heat” so it can be said that the illustrated material Ytong has a slightly higher specific heat capacity than that of polyurethane. From a physical point of view, the material parameter “thermal conductivity” generally refers to the ability of a given material to “conduct heat through the material in connection with stationary heat flux”, so it can be assumed as well as verified by measuring that Ytong also has a higher thermal conductivity than that of polyurethane. From a physical point of view, the newly proposed material parameter “heat dissipation rate” generally indicates the “rate of heat loss to the external environment in connection with non-stationary heat flux”, so it may also be assumed and verified by measuring that the heat dissipation rate of Ytong will be higher than that of polyurethane.

scholarly journals Aerosol optical properties in the North China Plain during HaChi campaign: an in-situ optical closure study

2011 ◽  
Vol 11 (12) ◽  
pp. 5959-5973 ◽  
Author(s):  
N. Ma ◽  
C. S. Zhao ◽  
A. Nowak ◽  
T. Müller ◽  
S. Pfeifer ◽  
...  
Keyword(s):  
Optical Properties ◽  
North China Plain ◽  
North China ◽  
Scattering Coefficient ◽  
Aerosol Optical Properties ◽  
Mean Values ◽  
The North ◽  
The North China Plain ◽  
The Mean

Abstract. The largest uncertainty in the estimation of climate forcing stems from atmospheric aerosols. In early spring and summer of 2009, two periods of in-situ measurements on aerosol physical and chemical properties were conducted within the HaChi (Haze in China) project at Wuqing, a town between Beijing and Tianjin in the North China Plain (NCP). Aerosol optical properties, including the scattering coefficient (σsp), the hemispheric back scattering coefficient (σbsp), the absorption coefficient (σap), as well as the single scattering albedo (ω), are presented. The diurnal and seasonal variations are analyzed together with meteorology and satellite data. The mean values of σsp, 550 nm of the dry aerosol in spring and summer are 280±253 and 379±251 Mm−1, respectively. The average σap for the two periods is respectively 47±38 and 43±27 Mm−1. The mean values of ω at the wavelength of 637 nm are 0.82±0.05 and 0.86±0.05 for spring and summer, respectively. The relative high levels of σsp and σbsp are representative of the regional aerosol pollution in the NCP. Pronounced diurnal cycle of $σsp, σap and ω are found, mainly influenced by the evolution of boundary layer and the accumulation of local emissions during nighttime. The pollutants transported from the southwest of the NCP are more significant than that from the two megacities, Beijing and Tianjin, in both spring and summer. An optical closure experiment is conducted to better understand the uncertainties of the measurements. Good correlations (R>0.98) are found between the values measured by the nephelometer and the values calculated with a modified Mie model. The Monte Carlo simulation shows an uncertainty of about 30 % for the calculations. Considering all possible uncertainties of measurements, calculated σsp and σbsp agree well with the measured values, indicating a stable performance of instruments and thus reliable aerosol optical data.

scholarly journals Improvement of the Heat-Dissipating Performance of Powder Coating with Graphene

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1321
Author(s):  
Fei Kung ◽  
Ming-Chien Yang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Surface Temperature ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Heat Dissipation ◽  
Powder Coating ◽  
Aluminum Plate ◽  
Graphene Nanoparticles

In this study, the epoxy powder was blended with graphene to improve its thermal conductivity and heat dissipation efficiency. The thermal conductivity of the graphene-loaded coating was increased by 167 folds. In addition, the emissivity of the graphene-loaded coating was 0.88. The epoxy powder was further coated on aluminum plate through powder coating process in order to study the effect on the performance of heat dissipation. In the case of natural convective heat transfer, the surface temperature of the graphene-loaded coated aluminum plate was 96.7 °C, which was 27.4 °C lower than that of bare aluminum plate (124.1 °C) at a heat flux of 16 W. In the case of forced convective heat transfer, the surface temperature decreased from 77.8 and 68.3 °C for a heat flux of 16 W. The decrease in temperature can be attributed to the thermal radiation. These results show that the addition of graphene nanoparticles in the coating can increase the emissivity of the aluminum plate and thus improving the heat dissipation.

scholarly journals Efficacy of Hospital Cleaning Agents and Germicides Against EpidemicClostridium difficileStrains

2007 ◽  
Vol 28 (8) ◽  
pp. 920-925 ◽  
Author(s):  
Warren N. Fawley ◽  
Sarah Underwood ◽  
Jane Freeman ◽  
Simon D. Baines ◽  
Katie Saxton ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Spore Form ◽  
Cleaning Agent ◽  
Cleaning Agents ◽  
A Cell ◽  
The Mean ◽  
Sporulation Rate ◽  
Hospital Cleaning

Objective.To compare the effects of hospital cleaning agents and germicides on the survival of epidemicClostridium difficilestrains.Methods.We compared the activity of and effects of exposure to 5 cleaning agents and/or germicides (3 containing chlorine, 1 containing only detergent, and 1 containing hydrogen peroxide) on vegetative and spore forms of epidemic and non-epidemicC. difficilestrains (3 of each). We carried out in vitro exposure experiments using a human fecal emulsion to mimic conditions found in situ.Results.Cleaning agent and germicide exposure experiments yielded very different results forC. difficilevegetative cells, compared with those for spores. Working-strength concentrations of all of the agents inhibited the growth ofC. difficilein culture. However, when used at recommended working concentrations, only chlorine-based germicides were able to inactivateC. difficilespores.C. difficileepidemic strains had a greater sporulation rate than nonepidemic strains. The mean sporulation rate, expressed as the proportion of a cell population that is in spore form, was 13% for all strains not exposed to any cleaning agent or germicide, and it was significantly increased by exposure to cleaning agents or germicides containing detergent alone (34%), a combination of detergent and hypochlorite (24%), or hydrogen peroxide (33%). By contrast, the mean sporulation rate did not change substantially after exposure to germicides containing either a combination of detergent and dichloroisocyanurate (9%) or dichloroisocyanurate alone (15%).Conclusions.These results highlight differences in the activity of cleaning agents and germicides againstC. difficilespores and the potential for some of these products to promote sporulation.

scholarly journals Comparisons between Mean and Turbulent Parameters of Aircraft-Based and Ship-Based Measurements in the Marine Atmospheric Boundary Layer

Atmosphere ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1088
Author(s):  
Min-Seong Kim ◽  
Byung Hyuk Kwon ◽  
Tae-Young Goo
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Atmospheric Boundary Layer ◽  
Radiation Flux ◽  
Sensible Heat Flux ◽  
Surface Flux ◽  
Marine Atmospheric Boundary Layer ◽  
The Mean ◽  
Good Agreement

The Structure des Echanges Mer-Atmosphère, Propriétés Océaniques/ Recherche Expérimentale (SEMAPHORE) experiment was conducted over the oceanic Azores current located in the Azores Basin. The evolution of the marine atmospheric boundary layer (MABL) was studied based on the evaluation of mean and turbulent data using in situ measurements by a ship and two aircrafts. The sea surface temperature (SST) field was characterized by a gradient of approximately 1 °C/100 km. The SST measured by aircraft decreased at a ratio of 0.25 °C/100 m of altitude due to the divergence of the infrared radiation flux from the surface. With the exception of temperature, the mean parameters measured by the two aircrafts were in good agreement with each other. The sensible heat flux was more dispersed than the latent heat flux according to the comparisons between aircraft and aircraft, and aircraft and ship. This study demonstrates the feasibility of using two aircraft to describe the MABL and surface flux with confidence.

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