Simultaneous estimation of SAR, thermal diffusivity, and damping using periodic power modulation for MRgFUS quality assurance.

Purpose: A crucial aspect of quality assurance in thermal therapy is periodic demonstration of the heating performance of the device. Existing methods estimate the specific absorption rate (SAR) from the temperature rise after a short power pulse, which yields a biased estimate as thermal diffusion broadens the apparent SAR pattern. To obtain an unbiased estimate, we propose a robust frequency-domain method that simultaneously identifies the SAR as well as the thermal dynamics.Methods: We propose a method consisting of periodic modulation of the FUS power while recording the response with MR thermometry (MRT). This approach enables unbiased measurements of spatial Fourier coefficients that encode the thermal response. These coefficients are substituted in a generic thermal model to simultaneously estimate the SAR, diffusivity, and damping. The method was tested using a cylindrical phantom and a 3 T clinical MR-HIFU system. Three scenarios with varying modulation strategies are chosen to challenge the method. The results are compared to the well-known power pulse technique.Results: The thermal diffusivity is estimated at 0.151 mm2s-1 with a standard deviation of 0.01 mm2s-1 between six experiments. The SAR estimates are consistent between all experiments and show an excellent signal-to-noise ratio (SNR) compared to the well established power pulse method. The frequency-domain method proved to be insensitive to B0-drift and non steady-state initial temperature distributions.Conclusion: The proposed frequency-domain estimation method shows a high SNR and provided reproducible estimates of the SAR and the corresponding thermal diffusivity. The findings suggest that frequency-domain tools can be highly effective at estimating the SAR from (biased) MRT data acquired during periodic power modulation.

Revised Enskog theory for Mie fluids: Prediction of diffusion coefficients, thermal diffusion coefficients, viscosities, and thermal conductivities.

Since the 1920s, the Enskog solutions to the Boltzmann equation have provided a route to predicting the transport properties of dilute gas mixtures. At higher densities, predictions have been limited to gases of hard spheres. In this work, we present a revised Enskog theory for multicomponent mixtures of Mie fluids, where the Barker-Henderson perturbation theory is used to calculate the radial distribution function at contact. With parameters of the Mie-potentials regressed to equilibrium properties, the theory is fully predictive for transport properties. The presented framework offers a link between the Mie potential and transport properties at elevated densities, giving accurate predictions for real fluids. For mixtures of noble gases, diffusion coefficients from experiments are reproduced within ±4%. For hydrogen, the predicted self-diffusion coefficient is within 10% of experimental data up to 200 MPa and at temperatures above 171 K. Binary diffusion coefficients of the CO2/CH4 mixture from simulations are reproduced within 20% at pressures up to 14.7 MPa. Except for xenon in the vicinity of the critical point, the thermal conductivity of noble gases and their mixtures is reproduced within 10% of the experimental data. For other molecules than noble gases, the temperature dependence of the thermal conductivity is under-predicted, while the density dependence appears to be correctly predicted. Predictions of the viscosity are within ±10% of the experimental data for methane, nitrogen, and argon up to 300 bar, for temperatures ranging from 233 to 523 K. At pressures up to 500 bar and temperatures from 200 to 800 K, the predictions are within ±15% of the most accurate correlation for the viscosity of air. Comparing the theory to an extensive set of measurements of thermal diffusion ratios, we find that 49% of the model predictions are within ±20% of the reported measurements. The predicted thermal diffusion factor differs by less than 15% from the simulation results of Lennard-Jones mixtures, even at densities well exceeding the critical density.

Thermal properties of municipal solid waste components and their relative significance for heat retention, conduction, and thermal diffusion in landfills.

Significant amounts of heat can be generated during the initial stages after wastes are deposited in landfills, primarily due to decomposition of food waste. Objectives of this study are to compile, examine and compare thermal properties of municipal solid waste (MSW) components, and liquid and gas phases in MSW landfills and their thermal responses that effect temperature increases in gas and leachate. Specific thermal properties examined include thermal conductivity, thermal diffusivity, and specific heat of waste materials deposited in landfills, liquids (water), and gases present. Compilation of these properties will allow in depth thermal analyses to evaluate heat transfer dynamics in landfills with different waste compositions. Examination of thermal characteristics of MSW components indicate that heat generated during decomposition of waste components would primarily be transferred to liquid (leachate) due to formation of water and gaseous components and their high specific heats. As a result, both the leachate and gases released from a landfill during the initial stages after wastes are deposited and when some oxygen is present as an electron acceptor will be warmer. Except for the metals and construction waste, it is likely that most waste components will have a significant temperature gradient during warming up and cooling off stages due to their low thermal conductivities and low thermal diffusivities. Even when the gas phase is at higher temperatures, it will take long time for waste materials (other than food waste and metals) to come to a uniform temperature during the heat generation (primarily due to decomposition of food waste) in a landfill.

Time-resolved spectroscopic mapping of vibrational energy flow in proteins: Understanding thermal diffusion at the nanoscale.

Vibrational energy exchange between various degrees of freedom is critical to barrier-crossing processes in proteins. Hemeproteins are well suited for studying vibrational energy exchange in proteins because the heme group is an efficient photothermal converter. The released energy by heme following photoexcitation shows migration in a protein moiety on a picosecond timescale, which is observed using time-resolved ultraviolet resonance Raman spectroscopy. The anti-Stokes ultraviolet resonance Raman intensity of a tryptophan residue is an excellent probe for the vibrational energy in proteins, allowing the mapping of energy flow with the spatial resolution of a single amino acid residue. This Perspective provides an overview of studies on vibrational energy flow in proteins, including future perspectives for both methodologies and applications.

Mass effects for thermodiffusion in dilute aqueous solutions.

Thermodiffusion is the phenomenon by which molecules in a mixture present concentration gradients in response to an imposed temperature gradient. Despite decades of investigations, this effect remains poorly understood at a molecular level. A common, phenomenological approach is to individuate the molecular factors that influence the Soret coefficient, the parameter that quantifies the resulting concentration-gradient. Experimental studies, often performed on organic mixtures, as well as simulations of model particle systems have evidenced that the difference in masses between the mixture components has an important effect on the amplitude of the Soret coefficient. Here, we use molecular dynamics simulations of a thermophoretic setting to investigate the mass dependence of the Soret coefficient in dilute aqueous solutions. An advantage of simulation approaches is that they are not limited in the range of explored molecular masses, which is often limited to isotopic substitutions in the experiments. Our simulations reveal that the mass dependence of the Soret coefficient in these solutions is in agreement with previous experimental and simulation work on molecular-size systems. In particular, it is sensitive to the relative mass difference between the solute and the solvent, but not to their absolute mass. Adjusting the mass of the solvent and of the solute can turn a thermophobic solution into a thermophilic one, where solute accumulation is reversed. This demonstrates that the mass effect can indeed compensate for the other contributions to the Soret coefficient. Finally, we find that changing the molecular moments of inertia has a much more limited impact as compared to a change in the total molecular mass.

Modeling thermodiffusion in aqueous sodium chloride solutions-Which water model is best?

Thermodiffusion is the migration of a species due to a temperature gradient and is the driving phenomenon in many applications ranging from early cancer detection to uranium enrichment. Molecular dynamics (MD) simulations can be a useful tool for exploring the rather complex thermodiffusive behavior of species, such as proteins and ions. However, current MD models of thermodiffusion in aqueous ionic solutions struggle to quantitatively predict the Soret coefficient, which indicates the magnitude and direction of species migration under a temperature gradient. In this work, we aim to improve the accuracy of MD thermodiffusion models by assessing how well different water models can recreate thermodiffusion in a benchmark aqueous NaCl solution. We tested four of the best available rigid non-polarizable water models (TIP3P-FB, TIP4P-FB, OPC3, and OPC) and the commonly used TIP3P and SPC/E water models for their ability to predict the inversion temperature and Soret coefficient in 0.5, 2, and 4M aqueous NaCl solutions. Each water model predicted a noticeably different ion distribution yielding different inversion temperatures and magnitudes of the Soret coefficient. By comparing the modeled Soret coefficients to published experimental values, we determine TIP3P-FB to be the water model that best recreates thermodiffusion in aqueous NaCl solutions. Our findings can aid future works in selecting the most accurate rigid non-polarizable water model, including water and ion parameters for investigating thermodiffusion through MD simulations.

Depilatory laser miniaturizes hair by inducing bystander dermal papilla cell necrosis through thermal diffusion.

OBJECTIVES: Depilatory laser targeting melanin has been widely applied for the treatment of hypertrichosis. Both selective photothermolysis and thermal diffusion have been proposed for its effect, but the exact mechanism of permanent hair reduction remains unclear. In this study, we explore the role of thermal diffusion in depilatory laser-induced permanent hair loss and determine whether nonpigmented cells are injured by thermal diffusion. MATERIALS AND METHODS: C57BL/6 mice in anagen and telogen were treated with alexandrite laser (wavelength 755 nm, pulse duration 3 milliseconds, fluence 12 J/cm2 , spot size 12 mm), respectively. Histological analysis, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, and transmission electron microscopic imaging were employed to evaluate the injury to hair follicle (HF) cells. The proliferation status of HF cells was examined by 5-bromo-2'-deoxyuridine pulse labeling. The number of HF stem cells was quantified by fluorescence-activated cell sorting. The size of the regenerated hair was determined by measuring its length and width. RESULTS: We found that irradiating C57BL/6 mice in anagen with alexandrite laser led to hair miniaturization in the next anagen. In addition to thermal disruption of melanin-containing cells in the precortex region, we also detected necrosis of the adjacent nonpigmented dermal papilla cells due to thermal diffusion. Dermal papilla cells decreased by 24% after laser injury, while the number of bulge stem cells remained unchanged. When the laser was delivered to telogen HFs where no melanin was present adjacent to the dermal papilla, thermal necrosis and cell reduction were not detected in the dermal papilla and no hair miniaturization was observed. CONCLUSION: Our results suggest that depilatory laser miniaturizes hair by inducing thermal necrosis of dermal papilla cells due to secondary thermal diffusion from melanin-containing precortex cells in the anagen hair bulbs.

Towards understanding specific ion effects in aqueous media using thermodiffusion.

Specific ion effects play an important role in scientific and technological processes. According to Hofmeister, the influence on the hydrogen bond network depends on the ion and leads to a specific order of the ions. Also thermodiffusion the mass transport caused by a temperature gradient is very sensitive to changes of the hydrogen bond network leading to a ranking according to hydrophilicity of the salt. Hence, we investigate various salt solutions in order to compare with the Hofmeister concept. We have studied three different sodium salts in water as a function of temperature (25-45[Formula: see text]C) and concentration (0.5-5 mol kg[Formula: see text]) using Thermal Diffusion Forced Rayleigh Scattering (TDFRS). The three anions studied, carbonate, acetate and thiocyanate, span the entire range of the Hofmeister series from hydrophilic to hydrophobic. We compare the results with the recent measurements of the corresponding potassium salts to see to what extent the cation changes the thermodiffusion of the salt.

Internal Degrees of Freedom as a Basis for Isotopic Effects in Thermodiffusion.

We present a model that relates isotope effects in thermodiffusion to changes in internal degrees of freedom associated with rotational and vibrational motion. The model uses general material transport equations for binary non-isothermal liquid systems, derived using non-equilibrium thermodynamics in our previous work. The equilibrium chemical potentials of the components at constant pressure are derived using statistical mechanics. In evaluating the model, we use experimental data on changes in the Soret coefficient of various hydrocarbons in perprotonated and perdeuterated cyclohexane. We also compare predictions of the model with experimental data on the Soret coefficient in isotopic mixtures. In all cases, the model is consistent with experimental data and computations.

Analytical analysis of anisotropic thermophoresis of a charged spheroidal colloid in aqueous media for extremely thin EDL cases.

Thermophoresis of charged spheroids has been widely applied in biology and medical science. In this work, we report an analysis of the anisotropic thermophoresis of diluted spheroidal colloids in aqueous media for extremely thin EDL cases. Under the boundary layer approximation, we formulate the thermophoretic velocity, the thermophoretic force, and the thermodiffusion coefficient of a randomly dispersed spheroid. The parametric studies show that under the aforementioned conditions, the thermophoresis is anisotropic and its thermodiffusion coefficient should be considered as a vector, DT . The thermodiffusion coefficient values and directions of DT are strongly related to the aspect ratio and the angle θ between the externally applied temperature gradient and the particle's axis of revolution: The increasing aspect ratio enlarges the thermodiffusion coefficient value DT of prolate (oblate) spheroids to a constant value when θ < 60° (θ > 45°), and it reduces DT of prolate (oblate) spheroids to a constant value when θ > 60° (θ < 45°). The thermodiffusion coefficient direction of both prolate and oblate spheroids deviates slightly from -∇T∞ for a small aspect ratio, and such deviation becomes serious for a large aspect ratio.

Thermodiffusion of aqueous solutions of various potassium salts.

Thermophoresis or thermodiffusion has become an important tool to monitor protein-ligand binding as it is very sensitive to the nature of solute-water interactions. However, the microscopic mechanisms underlying thermodiffusion in protein systems are poorly understood at this time. One reason is the difficulty to separate the effects of the protein system of interest from the effects of buffers that are added to stabilize the proteins. Due to the buffers, typical protein solutions form multicomponent mixtures with several kinds of salt. To achieve a more fundamental understanding of thermodiffusion of proteins, it is therefore necessary to investigate solutions of buffer salts. For this work, the thermodiffusion of aqueous potassium salt solutions has been studied systematically. We use thermal diffusion forced Rayleigh scattering experiments in a temperature range from 15 °C to 45 °C to investigate the thermodiffusive properties of aqueous solutions of five potassium salts: potassium chloride, potassium bromide, potassium thiocyanate, potassium acetate, and potassium carbonate in a molality range between 1 mol/kg and 5 mol/kg. We compare the thermophoretic results with those obtained for non-ionic solutes and discuss the thermophoresis of the salts in the context of ion-specific solvation according to the Hofmeister series.

An evaluation of electrocoagulation and thermal diffusion following radiofrequency microneedling using an in vivo porcine skin model.

BACKGROUND: Few studies exist that examined the role of radiofrequency microneedling (RFMN) in skin electrocoagulation. This research utilized a porcine model to understand bipolar dermal delivery from an RFMN device. AIMS: The objective of this study was to elucidate and compare the dermal thermal effects of a RFMN device producing 1 and 2 MHz signal amplitudes, with respective voltage and current gradients, utilizing noninsulated and insulated needles by examining the histologic effects on porcine skin. METHODS: Two separate animal studies were conducted to evaluate the electrocoagulation and thermal diffusion effects using the RFMN device. The electrocoagulation effects were assessed histologically using hematoxylin and eosin (H&E) staining, and heating effects were assessed through thermal imaging. RESULTS: Histology results of the thermal injury induced by insulated needles demonstrated that 2 MHz resulted in a narrow and concentrated coagulation zone as compared to 1 MHz. Further, the 1 MHz insulated needle resulted in ovular shaped tissue coagulation as compared to 2 MHz tissue coagulation that was columnar. Finally, full thermal diffusion occurs seconds after the set RF conduction time. CONCLUSION: The findings showed that 1 MHz insulated needle produces larger coagulations with an increase in power level, the 1 MHz noninsulated array was comparable to the 2 MHz insulated array with similar histologic features, and heat dissipates seconds after the set conduction time.

Analytical model for organic contaminant transport through GMB/CCL composite liner with finite thickness considering adsorption, diffusion and thermodiffusion.

A new analytical model for organic contaminant transport through GMB/CCL (geomembrane and compacted clay liner) composite liner is developed, which can consider adsorption, diffusion and thermodiffusion processes and is applicable for typical bottom boundary conditions. The separation of variables method is adopted to derive the solution. The present model is first verified against experimental results and a numerical model. The influence of thermodiffusion on organic contaminant transport in composite liner is then investigated. Toluene is adopted as the representative organic contaminant. The results reveal that when the Soret coefficient ST is not less than 0.01 K-1, the effect of thermodiffusion should be taken into account on the contaminant transport in GMB/CCL composite liner in wet landfills. When the Soret coefficient ST is 0.03 K-1, the breakthrough time of a GMB + 0.75 m CCL composite liner and a 2 m CCL would be overestimated by 20% to 76% due to omitting of the effect of thermodiffusion. Namely, the barrier performance would be greatly overestimated if the effect of thermodiffusion is neglected in these cases. In other aspects, the thermal conductivity of GMB and CCL has little effect on the contaminants transport in GMB/CCL composite liners, so there is no need to modify the materials for this parameter. The present model is an applicable tool for evaluating the barrier performance of the GMB/CCL composite liner, and can provide valuable advices for improving the liner materials.

Thermodynamic Insights by Microscale Thermophoresis into Translesion DNA Synthesis Catalyzed by DNA Polymerases Across a Lesion of Antitumor Platinum-Acridine Complex.

Translesion synthesis (TLS) through DNA adducts of antitumor platinum complexes has been an interesting aspect of DNA synthesis in cells treated with these metal-based drugs because of its correlation to drug sensitivity. We utilized model systems employing a DNA lesion derived from a site-specific monofunctional adduct formed by antitumor [PtCl(en)(L)](NO3)2 (complex AMD, en = ethane-1,2-diamine, L = N-[2-(acridin-9-ylamino)ethyl]-N-methylpropionamidine) at a unique G residue. The catalytic efficiency of TLS DNA polymerases, which differ in their processivity and fidelity for the insertion of correct dCTP, with respect to the other incorrect nucleotides, opposite the adduct of AMD, was investigated. For a deeper understanding of the factors that control the bypass of the site-specific adducts of AMD catalyzed by DNA polymerases, we also used microscale thermophoresis (MST) to measure the thermodynamic changes associated with TLS across a single, site-specific adduct formed in DNA by AMD. The relative catalytic efficiency of the investigated DNA polymerases for the insertion of correct dCTP, with respect to the other incorrect nucleotides, opposite the AMD adduct, was reduced. Nevertheless, incorporation of the correct C opposite the G modified by AMD of the template strand was promoted by an increasing thermodynamic stability of the resulting duplex. The reduced relative efficiency of the investigated DNA polymerases may be a consequence of the DNA intercalation of the acridine moiety of AMD and the size of the adduct. The products of the bypass of this monofunctional lesion produced by AMD and DNA polymerases also resulted from the misincorporation of dNTPs opposite the platinated G residues. The MST analysis suggested that thermodynamic factors may contribute to the forces that governed enhanced incorporation of the incorrect dNTPs by DNA polymerases.

MUC4-ErbB2 Oncogenic Complex: Binding studies using Microscale Thermophoresis.

The MUC4 membrane-bound mucin is a large O-glycoprotein involved in epithelial homeostasis. At the cancer cell surface MUC4 interacts with ErbB2 receptor via EGF domains to promote cell proliferation and migration. MUC4 is highly regarded as a therapeutic target in pancreatic cancer as it is not expressed in healthy pancreas, while it is neoexpressed in early preneoplastic stages (PanINs). However, the association/dissociation constant of MUC4-ErbB2 complex is unknown. Protein-protein interactions (PPIs) have become a major area of research in the past years and the characterization of their interactions, especially by biophysical methods, is intensively used in drug discovery. To characterize the MUC4-ErbB2 interaction, we used MicroScale Thermophoresis (MST), a powerful method for quantitative protein interaction analysis under challenging conditions. We worked with CHO cell lysates containing either the transmembrane ß subunit of MUC4 (MUC4ß) or a truncated mutant encompassing only the EGF domains (MUC4EGF3+1+2). MST studies have led to the characterization of equilibrium dissociation constants (Kd) for MUC4ß-ErbB2 (7-25 nM) and MUC4EGF3+1+2/ErbB2 (65-79 nM) complexes. This work provides new information regarding the MUC4-ErbB2 interaction at the biophysical level and also confirms that the presence of the three EGF domains of MUC4 is sufficient to provide efficient interaction. This technological approach will be very useful in the future to validate small molecule binding affinities targeting MUC4-ErbB2 complex for drug discovery development in cancer. It will also be of high interest for the other known membrane mucins forming oncogenic complexes with ErbBs at the cancer cell surface.

Thermophoresis of biological and biocompatible compounds in aqueous solution.

With rising popularity of microscale thermophoresis for the characterisation of protein-ligand binding reactions and possible applications in microfluidic devices, there is a growing interest in considering thermodiffusion in the context of life sciences. But although the understanding of thermodiffusion in non-polar mixtures has grown rapidly in recent years, predictions for associated mixtures like aqueous solutions remain challenging. This review aims to give an overview of the literature on thermodiffusion in aqueous systems, show the difficulties in theoretical description that arise from the non-ideal behaviour of water-mixtures, and highlight the relevance of thermodiffusion in a biological context. We find that the thermodiffusion in aqueous systems is dominated by contributions from heat of transfer, hydrogen bond interactions and charge effects. However, the separation of these effects is often difficult, especially in case of biological systems where a systematic exclusion of contributions may not be feasible.

Photoacoustic thermorelaxation microscopy for thermal diffusivity measurement.

Thermal diffusivity is one of the main parameters to characterize the thermo-physical properties of materials, and advances in its measurement technique will have significant impact on materials science and related applications. Here a photoacoustic (PA) thermorelaxation microscopy is proposed as a new noncontact method to measure the thermal diffusivity. By delivering co-focused heating/probing laser pulse pairs with tunable time delays, the sample's in situ thermal relaxation behavior after the heating pulse excitation can be photoacoustically monitored based on the temperature-dependent property of the Grueneisen parameter. We theoretically deduced the dependence of the obtained PA thermorelaxation time on the thermal diffusivity, and the results coincided well with simulations. The feasibility of this method was validated by various industrial and biological samples. This method provides a new strategy for high-resolution thermal diffusivity measurement with flexible measurement conditions, prefiguring great potential for material and biological applications.

Estudo do comportamento da cinética de secagem de morangos utilizando modelos da transferência de massa em secador solar / Study of the behavior of drying kinetics of strawberries using models of mass transfer

O morango (Fragaria L.) é um fruto que possui várias maneiras de preparo e consumo, devido à boa aceitação das suas características organolépticas, se torna um produto muito utilizado na indústria alimentícia. O presente trabalho teve por objetivo estudar o processo de transferência de massa em morangos por meio da desidratação da fruta em secador solar. A secagem foi realizada em um protótipo de secador solar de exposição direta com coletor solar acoplado por 16 horas e foram analisados cortes para geometria cilíndrica e geometria plana. Verificou-se que a geometria plana apresentou uma maior velocidade de secagem em relação à geometria cilíndrica. Os coeficientes de difusividade encontrados tiveram uma relação diretamente proporcional à temperatura de secagem e geometria.

Continuous Thermal Diffusion-Based Cerebral Blood Flow Monitoring in Adult Traumatic Brain Injury: A Scoping Systematic Review.

Thermal diffusion flowmetry (TDF) is an appealing candidate for monitoring of cerebral blood flow (CBF) in neurocritical-care patients as it provides absolute measurements with a high temporal resolution, potentially allowing for bedside intervention that could mitigate secondary injury. We performed a systematic review of TDF-regional(r)CBF measurements and their association with (1) patient functional outcome, (2) other neurophysiological parameters, and (3) imaging-based tissue outcomes. We searched MEDLINE, EMBASE, SCOPUS, BIOSIS, GlobalHealth, and the Cochrane Databases from inception to October 2018 and relevant conference proceedings published over the last 5 years. Nine articles that explored the relationship between TDF-rCBF, mortality, and Glasgow Outcome Scale (GOS) or GOS-Extended (GOS-E) at various intervals were included. Despite being based on an overall weak body of evidence, our analysis suggests a link between sustained low or high CBF and poor functional outcome. Twenty-five studies reporting associations with neurophysiological parameters were included. The available data also point to an association between low or high TDF-rCBF and intracranial hypertension. TDF-rCBF appears to correlate well with regional brain tissue oxygenation measurements. We found no studies reporting on imaging-based tissue outcome in relation to TDF. In conclusion, despite being based on a relatively weak body of evidence, the available literature suggests a link between consistently abnormal TDF-rCBF values, intracranial hypertension, and poor functional outcome. TDF-rCBF also appears to correlate well with regional measurements of brain tissue oxygenation. Currently, such monitoring should be considered experimental, requiring much further evaluation prior to widespread adoption.

Use of Microscale Thermophoresis (MST) to Measure Binding Affinities of Components of the Fusion Machinery.

Microscale thermophoresis is a relatively new technique used by an increasing number of academic laboratories to estimate relative binding affinities between ligand (analyte) that is titrated and a target (generally protein) that is either fluorescently labeled exogenously in the red or blue channel (labeled thermophoresis) or endogenously labeled via the presence of sufficient aromatic amino acid residues such as tryptophan (label-free thermophoresis). There are advantages and disadvantages to each technique; however, one major disadvantage of label-free thermophoresis is that protein-protein interactions cannot be measured, as generally most proteins have enough aromatic residues to generate an interfering signal. Thermophoresis can be used to determine steady-state binding affinities as between SNAREs and relevant binding partners of SNAREs and labeled thermophoresis is increasingly becoming a reliable technique to screen binding partners of fusion machinery to determine relevance in terms of direct biochemical interactions.