Temperature Dependence Of Solubility Research Articles

Experimental and thermodynamic investigation of gemifloxacin solubility in supercritical CO2 for the production of nanoparticles

The effective use of the supercritical technology in the production of new pharmaceutical formulations with greater bioavailability requires the determination of the solubility of pharmaceutical substances in supercritical CO2 (scCO2) at different conditions. In the current work, the solubility of an antibacterial compound, Gemifloxacin, was measured at various temperatures (308 to 338 K), and pressures (120 to 300 bar). This compound has a poor solubility in scCO2 (0.02 × 10−4 to 0.67 × 10−4 mole fraction or 0.0156 to 0.5891 g.kg−1). Furthermore, some popular empirical models and three thermodynamic approaches (SRK and PR equations of state, and the regular solution model) were applied to correlate and predict the solubility of Gemifloxacin in scCO2. The regular solution model with temperature-dependent solubility parameter (mean AARD% = 2.32–4.34) and the SRK-based model (mean AARD% = 7.47), exhibited the highest accuracy in fitting the experimental data.

Molecular Interaction Activities of Phenylephrine Hydrochloride with Aqueous System by using Physicochemical Properties at 298.15, 303.15, 308.15 and 313.15 K

Abstract: The solubilizing tendency of the phenylephrine hydrochloride (PHC) with water was supported by the intermolecular interaction (IMI). The effect of PHC concentration with water molecules on the interaction by using physicochemical properties (PCP) was investigated at 298.15, 303.15, 308.15 and 313.15 K. The PCP such as density (ρ, g cm -3 ), Apparent Molar Volume (Vϕ,cm 3 ·mol−1 ), viscosity (η, mPa.s), and surface tension (γ,mNm-1 ) of PHC in aqueous solution have been determined at 298.15, 303.15, 308.15 and 313.15 K. The PCP determine the state of intermolecular forces (IMF) between PHC and water (W). The concentration of PHC ranged from 0.02- 0.10 millimolar (mM) as a binary system in water. This study shows molecular interaction mechanism moderated through PCPs to assess state of IMF produced on PHC-Water interaction at 298.15, 303.15, 308.15 and 313.15 K which revealed that structural potential of PHC with water responsible for develop interaction. The PCP data confirms structural behavior of PHC with water for intermolecular interaction and increases with increasing concentration of PHC. The temperature dependent solubility determined at 298.15, 303.15, 308.15 and 313.15 K which indicates that on increasing temperature the significant change found in PCP. This is due to structure breaking effects of PHC with water furnished disruption of hydrogen bond (HB) in water and electrostatic interactions (EI).

Temperature Dependent Solubility and Catalytic behaviour of K2CO3 and Na2CO3 during Transesterification of Calophyllum Inophyllum Oil and its Fuel Properties

AbstractThe current work is focused on the solubility and catalytic behaviour of K2CO3, and Na2CO3 during the synthesis of biodiesel from Calophyllum Inophyllum oil (CIO) in methanol. The solubility of K2CO3, and Na2CO3 in methanol is not straight forward, as both form their respective methoxides and bicarbonates on solubility in methanol. Therefore to understand catalytic behaviour of both carbonates, it is essential to estimate sodium and potassium methoxides, and bicarbonates formed at different temperatures. In this regard, the catalytic behaviour of both carbonates was studied between 50 °C to 65 °C. Therefore, solubility behaviour of both carbonates explored during the synthesis of biodiesel from CIO by transesterification process. At higher temperature, the concentration of potassium and sodium methoxides decreased and their bicarbonate concentration increased. This solubility behaviour found to be more useful to differentiate homogeneous and heterogeneous catalytic route for biodiesel synthesis. At higher temperature, 65 °C, K2CO3, and Na2CO3 exhibited heterogeneous catalytic behaviour, but Na2CO3 showed relatively higher heterogeneous catalytic behaviour as it form higher concentration of insoluble sodium bicarbonate. Therefore, Na2CO3 could be a better heterogeneous catalyst for biodiesel synthesis at higher temperatures, 65 °C, as it produces low concentration of sodium methoxide which is an advantage from post biodiesel treatment standpoint.

Hydrogen in Compounds and Alloys with A15 Structure

In the present work, a theoretical study of atomic ordering in the A3BCx alloy is carried out. The mutual influence of the ordering and solubility of impurity C in the A3B alloy is studied. The dependences of solubility on the composition of the alloy, temperature, degree of long-range order are found and studied. In addition, the criteria for the manifestation of extremity in the concentration and temperature dependences of solubility are obtained. The atomic ordering is studied using the average-energies’ method; the features of the C impurity solubility in the A3B alloy are elucidated using the configuration method. Experiments confirming the results of the theory are currently unknown to authors. However, the available experimental data on determining the temperatures of martensitic transformation (Tm) and superconducting transition (Tc) for the Nb3SnHx alloy allow us to hope and assert a possible agreement between the data of theory and experiment.

Thermoresponsive and Photocrosslinkable Poly(2-alkyl-2-oxazoline) Toolbox - Customizable Ultralow-Fouling Hydrogel Coatings for Blood Plasma Environments.

This study focuses on developing surface coatings with excellent antifouling properties, crucial for applications in the medical, biological, and technical fields, for materials and devices in direct contact with living tissues and bodily fluids such as blood. This approach combines thermoresponsive poly(2-alkyl-2-oxazoline)s, known for their inherent protein-repellent characteristics, with established antifouling motifs based on betaines. The polymer framework is constructed from various monomer types, including a novel benzophenone-modified 2-oxazoline for photocrosslinking and an azide-functionalized 2-oxazoline, allowing subsequent modification with alkyne-substituted antifouling motifs through copper(I)-catalyzed azide-alkyne cycloaddition. From these polymers surface-attached networks are created on benzophenone-modified gold substrates via photocrosslinking, resulting in hydrogel coatings with several micrometers thickness when swollen with aqueous media. Given that poly(2-alkyl-2-oxazoline)s can exhibit a lower critical solution temperature in water, their temperature-dependent solubility is compared to the swelling behavior of the surface-attached hydrogels upon thermal stimulation. The antifouling performance of these hydrogel coatings in contact with human blood plasma is further evaluated by surface plasmon resonance and optical waveguide spectroscopy. All surfaces demonstrate extremely low retention of blood plasma components, even with undiluted plasma. Notably, hydrogel layers with sulfobetaine moieties allow efficient penetration by plasma components, which can then be easily removed by rinsing with buffer.

In Vitro Studies Regarding the Effect of Cellulose Acetate-Based Composite Coatings on the Functional Properties of the Biodegradable Mg3Nd Alloys.

Magnesium (Mg) alloys are adequate materials for orthopedic and maxilo-facial implants due to their biocompatibility, good mechanical properties closely related to the hard tissues, and processability. Their main drawbacks are the high-speed corrosion process and hydrogen release. In order to improve corrosion and mechanical properties, the Mg matrix can be strengthened through alloying elements with high temperature-dependent solubility materials. Rare earth elements (RE) contribute to mechanical properties and degradation improvement. Another possibility to reduce the corrosion rate of Mg-based alloys was demonstrated to be the different types of coatings (bioceramics, polymers, and composites) applied on their surface. The present investigation is related to the coating of two Mg-based alloys from the system Mg3Nd (Mg-Nd-Y-Zr-Zn) with polymeric-based composite coatings made from cellulose acetate (CA) combined with two fillers, respectively hydroxyapatite (HAp) and Mg particles. The main functions of the coatings are to reduce the biodegradation rate and to modify the surface properties in order to increase osteointegration. Firstly, the microstructural features of the experimental Mg3Nd alloys were revealed by optical microscopy and scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy. Apart from the surface morphology revealed by SEM, the roughness and wettability of all experimental samples were evaluated. The corrosion behavior of the uncoated and coated samples of both Mg3Nd alloys was investigated by immersion testing and electrochemical testing using Simulated Body Fluid as the medium. The complex in vitro research performed highlights that the composite coating based on CA with HAp particles exhibited the best protective effect for both Mg3Nd alloys.

First-principles study on mechanical properties and retention behaviors of hydrogen in W by additions of Re and Mo

Understanding the alloying effects on service performances of hydrogen in W has been regarded as a hot issue for designing plasma-facing materials. In our work, first-principles calculation was used to comparatively investigate the thermodynamic stabilities, mechanical properties and retention behaviors of hydrogen in W by additions of Re and Mo. It is shown that the ductility and damage tolerance of WH phases are improved through the alloying of Re and Mo, and one of Re plays a more significant role. Moreover, the temperature-dependent solubility, diffusivity, and permeability of hydrogen in W, WRe and WMo alloys are calculated by combining Sievert's law and transition state theory. The derived results match well with experimental observations in the literature, and offer direct explanations for different influences of additive Re and Mo on hydrogen retention.

The Temperature-Dependent Phase Transformation and Microstructural Characterisation in In-Sn Solder Alloys

Indium-based solder alloys are considered candidates for the next generation of low-temperature solder materials, especially for superconducting joints because of the properties of the β-In3Sn phase. The temperature-dependent phase transformation and thermal expansion behaviour of two different solder compositions including In-35Sn (in wt.%) and In-25.6Sn have been characterised using an in situ synchrotron powder X-ray diffraction method. The c-axis of the β-In3Sn unit cell in the In-35Sn alloy exhibited a complex relationship with increasing temperature compared to the positive increasing trend in In-25.6Sn due to the temperature-dependent solubility of Sn in β-In3Sn and change in the volume fraction of phases commencing at 80°C. In situ heating scanning electron microscopy recorded a real-time melting-solidification microstructure variation and phase transition during annealing at 90°C that was further analysed using energy dispersive X-ray spectroscopy. The observations are discussed with respect to the lattice parameters of the γ-InSn4 and β-In3Sn phases and the proportions and composition of both phases present within the alloys.

Modeling the temperature-dependent solubility of salts in organic solvents

The temperature-dependent solubility of salts in organic solvents is of particular interest in nearly water-free multi-component systems, such as chemical reactions at extreme conditions, e.g., carboxylation reactions or Suzuki-Miyaura reactions. In this work, a novel modeling approach is proposed, which utilizes the correlative Pitzer model and the equation of state ePC-SAFT advanced to model the temperature-dependent solubility of salts in organic solvents. The proposed approach was applied to model the temperature-dependent solubility of CsCl in the organic solvents methanol, ethanol, and N-methyl-2-pyrrolidone (NMP) over a temperature range from T = 273.15 K to T = 333.15 K. The Pitzer model was used to correlate accurately temperature-dependent osmotic coefficients (OC). Pitzer was then used to determine ePC-SAFT binary interaction parameters and to determine the thermodynamic solubility product KSP of the salts over the temperature. Missing OC data were measured in this work using vapor-pressure osmometer for Na2CO3 and Cs2CO3. The resulting KSP values do not depend on the solvent, and they were used as an input into ePC-SAFT to model the temperature-dependent solubility of salts in organic solvents. Excellent agreement was achieved for CsCl, and the approach was then transferred to carbonate salts (Na2CO3 and K2CO3), which form multiple hydrates with water. Hypothetical KSP values of the anhydrous form were determined via the van ’t Hoff equation and successfully allowed modeling of the solubility of (anhydrous) Na2CO3 and K2CO3 in methanol, ethanol, and NMP. To conclude, a combination of accurate KSP values together with a robust thermodynamic model, such as ePC-SAFT advanced, can help to reduce the experimental burden in screening the solubility of salts in organic solvents over the temperature.

Temperature responsive crosslinked starch-kraft lignin macromolecule

Starch is a natural polymer with a relatively simple structure and limited solubility in water. Kraft lignin (KL) is a complex biopolymer obtained as a by-product from the delignification of wood and grasses. The present work reports developing a temperature-responsive high molecular weight macromolecule from crosslinking KL and starch (KLS). The NMR and XPS analyses quantified the changes in the aromatic and anhydroglucose units of KL and starch, observing a higher content of C-O-C bonds, which confirms the presence of glycerol ether cross-linkages between starch and KL in KLS. The rheological analysis of KLS dispersions revealed the formation of a thermo-responsive structured network. The temperature-dependent water solubility and rheological characteristics of KLS were related to the presence of hydrophilic starch chains, crosslinking degree, and physicochemical characteristics of KL. The incorporation of KL and ether crosslinks increased the thermal stability of KLS. Because of its multiple functional groups and large molecular weight (3.6–4.2 × 105 g/mol) that was arranged in an extended globular shape, KLS-5 formed a gel-like structure after a heating-cooling treatment. Overall, the results confirmed that incorporating lignin in starch would fabricate sustainable materials with potentially altered applications, such as temperature-responsive hydrogels and films.

Methods of incorporation of new reaction products in thermodynamic databases of cementitious systems

Strategic blending of supplementary cementitious materials (SCMs) into ordinary portland cement (OPC) helps reduce energy use and greenhouse gas emissions from concrete production. Expanding thermodynamic databases to include new reaction products from blended cements improves computational approaches used to understand the impact of blending SCMs with cement. Determination of thermodynamic parameters of cement reaction products based on temperature-dependent solubility is widely used in cement research; however, assumptions, limitations, and potential errors due to intercorrelation of the thermodynamic parameters in these calculation methods are rarely discussed. Here, methods for obtaining thermodynamic parameters are critically reviewed, including discussion of experimental validation. The discussion herein provides useful guidance to improve and validate the process of determining thermodynamic parameters of new reaction products from SCM-OPC reactions.

Organic solvent free PbI2 recycling from perovskite solar cells using hot water

Perovskite solar cells represent an emerging and highly promising renewable energy technology. However, the most efficient perovskite solar cells critically depend on the use of lead. This represents a possible environmental concern potentially limiting the technologies’ commercialization. Here, we demonstrate a facile recycling process for PbI2, the most common lead-based precursor in perovskite absorber material. The process uses only hot water to effectively extract lead from synthetic precursor mixes, plastic- and glass-based perovskites (92.6 – 100% efficiency after two extractions). When the hot extractant is cooled, crystalline PbI2 in high purity (> 95.9%) precipitated with a high yield: from glass-based perovskites, the first cycle of extraction / precipitation was sufficient to recover 94.4 ± 5.6% of Pb, whereas a second cycle yielded another 10.0 ± 5.2% Pb, making the recovery quantitative. The solid extraction residue remaining is consequently deprived of metals and may thus be disposed as non-hazardous waste. Therefore, exploiting the highly temperature-dependent solubility of PbI2 in water provides a straightforward, easy to implement way to efficiently extract lead from PSC at the end-of-life and deposit the extraction residues in a cost-effective manner, mitigating the potential risk of lead leaching at the perovskites’ end-of-life.

Physiologically Based Biopharmaceutics Modeling of Food Effect for Basmisanil: A Retrospective Case Study of the Utility for Formulation Bridging

Basmisanil, is a lipophilic drug substance, exhibiting poor solubility and good permeability (BCS class 2). A validated physiologically based biopharmaceutics model (PBBM) has been previously described for tablets dosed in the fed state. The PBBM captured the less than proportional increases in exposure at higher doses well and indicated that absorption was dissolution rate-limited below 200 mg while solubility was limiting for higher doses. In this study, a model for dosing in the fasted state is described and is verified for simulation of the food effect where exposures were ~1.5 fold higher when a 660 mg tablet was given with food. The model is then applied to simulate the food effect for a granules formulation given at a lower dose (120 mg). The food effect at the lower dose was reasonably simulated with a ratio of simulated/observed food effect of 1.35 for Cmax and 0.83 for AUC. Sensitivity analysis was carried out for uncertain model parameters to confirm that the model could predict the magnitude of the positive food effect with moderate to high confidence. This study suggests that a verified PBBM can provide a useful alternative to a repeat food effect study when formulation changes are minor. However, there is need for further evaluation of the approach and a definition of what formulation changes are minor in this context. In addition, this work highlights some uncertainties in the handling of solubility in PBBM, in particular around temperature dependency of solubility and the parameterization of bile salt solubilization using measurements in biorelevant media.

Strategy for Fast Decision on Material System Suitability for Continuous Crystallization Inside a Slug Flow Crystallizer.

There is an increasing focus on two-phase flow in micro- or mini-structured apparatuses for various manufacturing and measurement instrumentation applications, including the field of crystallization as a separation technique. The slug flow pattern offers salient features for producing high-quality products, since narrow residence time distribution of liquid and solid phases, intensified mixing and heat exchange, and an enhanced particle suspension are achieved despite laminar flow conditions. Due to its unique features, the slug flow crystallizer (SFC) represents a promising concept for small-scale continuous crystallization achieving high-quality active pharmaceutical ingredients (API). Therefore, a time-efficient strategy is presented in this study to enable crystallization of a desired solid product in the SFC as quickly as possible and without much experimental effort. This strategy includes pre-selection of the solvent/solvent mixture using heuristics, verifying the slug flow stability in the apparatus by considering the static contact angle and dynamic flow behavior, and modeling the temperature-dependent solubility in the supposed material system using perturbed-chain statistical associating fluid theory (PC-SAFT). This strategy was successfully verified for the amino acids l-alanine and l-arginine and the API paracetamol for binary and ternary systems and, thus, represents a general approach for using different material systems in the SFC.

Solubility analysis of 18 active pharmaceutical ingredients and intermediates in the non-polar solvents dioxane, toluene and cyclopentyl methyl ether

The temperature dependent solubility of 18 organic compounds, of which some are active pharmaceutical ingredients, was measured in 1,4-dioxane, toluene and cyclopentyl methyl ether over a temperature range between 0 and 70 °C using a turbidity method. The solubility of the studied compounds in the three solvents increases with temperature in all binary solute-solvent systems, and all compounds exhibit a higher solubility in 1,4-dioxane than in toluene and cyclopentyl methyl ether. The non-ideal behaviour of the binary systems was evaluated in terms of the activity coefficient. All the compounds in toluene presented a positive deviation from ideal solution, while both positive and negative deviations were observed for the model compounds in the other two apolar solvents. From the solubility and the activity coefficient, a number of thermodynamic models including van’t Hoff, Apelblat, λh, Margules, van Laar, Wilson, and the Non-Randomness Two Liquids (NRTL) were used for the correlation of the experimental data. The NRTL and the van’t Hoff equations present closer overall correlations, while the Margules and the λh models show deviations >5 % for several compounds in the three solvent systems. The mixing thermodynamic properties of the several solute-solvent systems were further analyzed by the van ‘t Hoff and Wilson equations for a better understanding of the solution behaviour. The analysis revealed systems with apparent ideal behaviour where counteracting non-ideality effects cancel each other’s.

Solubility of mesalazine in aqueous solutions of two betaine-based deep eutectic solvents at different temperatures: Data correlation and thermodynamic analysis

Temperature-dependent solubility data for mesalazine in the cosolvency systems composed of water and deep eutectic solvents (DESs) obtained from betaine as a hydrogen bond acceptor and ethylene glycol (EG) or propylene glycol (PG) as hydrogen bond donors were determined by a shake flask technique at 293.15–313.15 K under atmospheric pressure (≈ 85 kPa). Based on the results, type of hydrogen bond donor plays an important role in solubilization power of DESs for mesalazine; so that, the values of mesalazine solubility in betaine/EG DES + water mixtures were higher than that the other. It was also found that the solubility of mesalazine in the investigated mixtures increased by increasing mass fractions of DESs as well as enhancing temperature reaching to the maximum values in neat DESs at 313.15 K. The Hansen solubility parameters for mesalazine, neat solvents of betaine/EG or betaine/PG DESs and water were calculated to predict the solubility of drug in the investigated systems. Moreover, X-ray powder diffraction was served to analyze the equilibrium solid phase crystal of mesalazine and the results turns out that no polymorphic transformation or crystal transition during the whole solvent crystallization process. The solubility data were then represented with some cosolvency models (Jouyban-Acree, Jouyban-Acree-van’t Hoff and so on) and activity coefficient models (NRTL, Wilson and UNIQUAC). According to the calculated percentage averaged relative deviations (ARD%) for back-calculated data, all the studied models present good correlation. Additionally, an endothermic and enthalpy-driven process for mesalazine dissolution in aqueous mixtures of betaine-based DESs obtained from apparent thermodynamic analysis.

1-Propyl-4(5)-Methylimidazole Isomers for Temperature Swing Solvent Extraction.

Temperature swing solvent extraction (TSSE) utilizes an amine solvent with temperature-dependent water solubility to dissolve water at a lower temperature to concentrate or crystallize the brine and the phases are separated. Then, the water in solvent mixture is heated to reduce water solubility and cause phase separation between the solvent and water. The solvent and de-salted water phases are separated, and the regenerated solvent can be recycled. Issues with current TSSE solvents include the high solvent in water solubility and the high solvent volatility. This project used the highly tunable platform molecule imidazole to create two 1-butylimidazole isomers, specifically 1-propyl-4(5)-methylimidazole, to test their effectiveness for TSSE. The imidazoles take in more water than their current state-of-the-art counterparts, but do not desalinate the product water and dissolve in water at higher concentrations. Thus, while imidazoles make intriguing candidates for TSSE, further work is needed to understand how to design imidazoles that will be useful for TSSE applications.

The roles of polymer relaxation phenomena, aqueous dye solubility and the physical properties of water in the mechanism of adsorption of a disperse dye on poly(ethylene terephthalate) fibres: Part 3 physical properties of water and water‐derived fibre properties

AbstractIn the absence of published information regarding the temperature dependency of water‐derived poly(ethylene terephthalate) fibre properties, the findings reported for the thermally regulated interactions between water and 100% amorphous poly(ethylene terephthalate) materials were interpreted from the perspective of the amorphous domains that reside within semi‐crystalline polyester textile fibres. This analysis suggests that the pronounced temperature dependent uptake of a commercial grade disperse dye on poly(ethylene terephthalate) fabric achieved during an aqueous dyeing process at temperatures between 30 and 130°C is the likely result of the combination of three separate, but inherently inter‐related, thermally activated phenomena, namely, polymer structural relaxation, in which polymer glass transition assumes a dominant role, dissolution of disperse dye in the aqueous dyebath, as well as various water–fibre interactions, in the guise of water sorption, water molecule diffusivity, water‐induced swelling and water‐induced plasticisation. Although thermally regulated macromolecular relaxation processes adopt the principal role in dye uptake, temperature dependent dye solubility and water‐derived fibre properties nevertheless likely provide crucially important supportive roles.

Quantification of Caffeine Interactions in Choline Chloride Natural Deep Eutectic Solvents: Solubility Measurements and COSMO-RS-DARE Interpretation.

Solubility of active pharmaceutical ingredients is an important aspect of drug processing and formulation. Although caffeine was a subject of many studies aiming to quantify saturated solutions, many applied solvents suffer from not being environmentally friendly. This work fills this gap by presenting the results of solubility measurements in choline chloride natural deep eutectic solvents, ccNADES, comprising one of seven of the following polyalcohols: glycerol, sorbitol, xylitol, glucose, sucrose, maltose and fructose. The ratio of ccNADES components was optimized for maximizing caffeine solubility at room temperature. Additionally, temperature dependent solubility was measured for the first four systems exhibiting the highest solubility potential, both in their neat forms and in mixtures with water. Results were used for intermolecular interactions assessments using the COSMO-RS-DARE approach, which led to a perfect match between experimental and computed solubility values. An important methodological discussion was provided for an appropriate definition of the systems. Surprising linear trends were observed between the values of fitting parameters and water-ccNADES composition. In addition, comments on selection of the values of the fusion thermodynamic parameters were provided, which led to the conclusion that COSMO-RS-DARE solubility computations can effectively compensate for the inaccuracies of these important physicochemical properties.

Dynamic doping and Cottrell atmosphere optimize the thermoelectric performance of n-type PbTe over a broad temperature interval

High thermoelectric energy conversion efficiency requires a large figure-of-merit, zT, over a broad temperature range. To achieve this, we optimize the carrier concentrations of n-type PbTe from room up to hot-end temperatures by co-doping Bi and Ag. Bi is an efficient n-type dopant in PbTe, often leading to excessive carrier concentration at room temperature. As revealed by density functional theory calculations, the formation of Bi and Ag defect complexes is exploited to optimize the room temperature carrier concentration. At elevated temperatures, we demonstrate the dynamic dissolution of Ag2Te precipitates in PbTe in situ by heating in a scanning transmission electron microscope. The release of n-type Ag interstitials with increasing temperature fulfills the requirement of higher carrier concentrations at the hot end. Moreover, as characterized by atom probe tomography, Ag atoms aggregate along parallel dislocation arrays to form Cottrell atmospheres. This results in enhanced phonon scattering and leads to a low lattice thermal conductivity. As a result of the synergy of dynamic doping and phonon scattering at decorated dislocations, an average zT of 1.0 is achieved in n-type Bi/Ag-codoped PbTe between 400 and 825 K. Introducing dopants with temperature-dependent solubility and strong interaction with dislocation cores enables simultaneous optimization of the average power factor and thermal conductivity, providing a new concept to exploit in the field of thermoelectrics.