Ethanol as an alternative to water vapor for saving energy and fossil fuels in thermoelectric plants

This article proposes the use of ethanol in a 96% azeotropic mixture as an alternative to water vapor in thermoelectric generators with notable advantages in saving fuel. As is known, water is a cheap resource, available everywhere in a liquid state. However, water has an unusually high heat of vaporization and an equally high boiling point, so converting water to steam requires consuming large amounts of fossil fuels to break the hydrogen bonds in this substance. In contrast, evaporating ethanol requires only 37 percent of the fuel needed to evaporate water. In addition, water, before turning into steam, needs to be softened and treated with chemicals to prevent oxidation and scale deposits in pipes. If quality ethanol is used, this process of adjusting the water would not be necessary, which represents another saving. On the other hand, it is possible to resort to the use of solar heaters to raise the temperature of the ethanol to around 70ºC to later heat it to 80ºC or more, if necessary, with fossil fuels, making more significant savings. Objectives: To propose the replacement of water vapor by ethanol vapor as a working fluid to move the turbines of thermoelectric plants to reduce the consumption of fossil fuels. Methodology: Analyze the physical properties of water and compare them with those of ethanol to know the advantages and disadvantages of one and the other as working fluids Contribution: Through small modifications in thermoelectric plants it is possible to reconvert them to operate with ethanol vapor and save on fossil fuels.

Additive Effect on the Structure of PEDOT:PSS Dispersions and Its Correlation with the Structure and Morphology of Thin Films

We reported on the interaction between poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and high-boiling-point additives in PEDOT:PSS aqueous dispersions and in the final polymer films with the aim of stablishing correlations between the structure of both inks and solid thin films. By Small-Angle X-ray Scattering (SAXS) using synchrotron radiation, it was found that the structural changes of dispersions of PEDOT:PSS with high-boiling-point additives can be explained as a two-step mechanism depending on the additive concentration. A compaction of PEDOT:PSS grains was observed at low concentrations while a swelling of the grains together with a phase segregation between PEDOT and PSS segments was evidenced at larger concentrations. Thin films’ morphology and structure were investigated by atomic force microscopy (AFM) and synchrotron Grazing Incidence Wide-Angle X-ray Scattering (GIWAXS) respectively. Our two-step model provides an explanation for the small and sharp domains of PEDOT:PSS thin films observed for low-additive concentrations (first step) and larger domains and roughness found for higher-additive concentrations (second step). A reduction of the ratio of PSS in PEDOT:PSS thin films upon the presence of additives was also observed. This can be related to a thinning of the PSS shells of PEDOT:PSS grains in the dispersion. The results discussed in this work provide the basis for a controlled tuning of PEDOT:PSS thin films structure and the subsequent electrical properties.

Effective drug release from safe ultrasound-triggered nanocarriers

Selective delivery of medication into specified tissue targets would realize the promise ofpersonalized medicine with minimal side effects. Such an approach could be particularlytransformative for patients with brain disorders, in whom drugs could be released in the impairedbrain circuits at high concentration while sparing other brain regions and organs. Focusedultrasound provides noninvasive and practical means to release drugs from nanocarriers selectivelyat its target. However, which nanoparticle formulations provide safe and effective release andunder which ultrasound parameters has been unclear. To expedite regulatory approval, wetested release effectiveness from nanocarriers filled with perfluorocarbon cores of relatively highboiling points (up to 142◦C). We confirmed the safety of these nanocarriers in non-humanprimates. Crucially, we found that these safe, high-boiling-point nanocarriers can be used foreffective release so long as they are activated by ultrasound of frequencies lower than thoseused previously (300 kHz). This study informs the formulation and release parameters for safeand effective drug delivery in specific parts of the body or brain regions.

Synergistic interaction of renewable nipagin and eugenol for aromatic copoly(ether ester) materials with desired performance

Naturally occurring nipagin and eugenol were used as the collaborative starting materials for poly(ether ester) polymers. In this study, two series of nipagin and eugenol-derived copoly(ether ester)s, PHN11−xE1x and PHN11−xE2x (x = 0%, 5%, 10%, 15%, 20%), were prepared with renewable 1,6-hexanediol as a comonomer. The nipagin-derived component acts as the renewable surrogate of petroleum-based dimethyl terephthalate (DMT), while the eugenol-derived component acts as the cooperative property modifier of parent homopoly(ether ester) PHN1. 1,6-Hexanediol was chosen as the spacer because of its renewability, high boiling point, and short chain to enhance the glass transition temperatures (Tgs) of materials. The molecular weights and chemical structures were confirmed by gel permeation chromatograph (GPC), NMR and FTIR spectroscopies. Thermal and crystalline properties were studied by thermal gravimetric analysis (TGA), differential scanning calorimetric (DSC) and wide-angle X-ray diffraction (WXRD). The tensile assays were conducted to evaluate the mechanical properties. The results suggested that properties of this kind of poly(ether ester)s could be finely tuned by the relative content of two components for the desired applications (elastomer, rubbery) suitable for different scenarios from polyethylene glycol terephthalate (PET) and polybutylene terephthalate (PBT).

Measurement and Thermodynamic Modeling for CO2 Solubility in the N-(2-Hydroxyethyl) Piperazine + Water System

Amine scrubbing is the most important technique for capturing CO2. The cyclic diamine N-(2-Hydroxyethyl)-piperazine (HEPZ), a derivative of piperazine, with good mutual solubility in aqueous solution, a low melting point, and a high boiling point, has the potential to replace PZ as an activator added in the mixed amine system to capture CO2. In this study, the solubility of CO2 in aqueous HEPZ solutions was determined for three HEPZ concentrations and four temperatures. The VLE data for HEPZ-H2O were obtained using a gas–liquid double circulation kettle at pressure 30–100 kPa, and the thermodynamic model for the HEPZ-H2O-CO2 system was built in Aspen Plus based on the electrolytic non-random two-liquid (ENRTL) activity model. The physical parameters for HEPZ and the interaction parameters for ENRTL, along with reaction constants of carbamate reactions, were regressed. Using the thermodynamic model, the CO2 cyclic capacity, speciation with loading, and heat of reaction for the CO2 capture system by the aqueous HEPZ solution are predicted and analyzed.

Experimental Study on Reducing the Heat of Curing Reaction of Polyurethane Polymer Grouting Material

Polyurethane polymer grouting material has been effectively applied and promoted in the repair of road damages in nonfrozen areas. However, this material undergoes an exothermic reaction in the curing stage, which can cause a thermal disturbance in the frozen soil subgrade. To minimize the influence of the thermal disturbance of the polyurethane polymer grouting material in the repair of the frozen soil subgrade, an experiment was conducted to reduce the heat of the curing reaction under the influence of different proportions of a foaming agent, high-boiling point solvent, catalyst, and prepolymer. According to these test results, a proportioning scheme for the low exothermic polymer grouting material was formulated. The results indicated that the curing reaction temperature threshold of the polyurethane polymer grouting material was negatively related to the proportion of physical foaming agent (HCFC-141b) and high-boiling point solvent and positively related to the proportion of water weight. In the three stages of rapid temperature rise, slow temperature rise, and constant temperature, the rate of the temperature rise of the low exothermic polymer grouting material was lower than that of the common polymer, and the curing temperature threshold was 30.34% lower at a value of 101°C. At a density of 80 kg/m3, the compressive strength and tensile strength of the low heat release polymer grouting material were lower than those of the common polymer grouting material, thereby ensuring the excellent performance of polyurethane foam and providing a theoretical reference for the rapid repair of frozen soil roadbed diseases.

Improvement of ligand-free modification strategy to obtain water-stable up-converting nanoparticles with bright emission and high reaction yield

Water-dispersible up-converting nanoparticles (UCNPs) are known to be very effective in biomedical applications. Research groups have paid special attention to the synthesis of hydrophilic UCNPs with good physicochemical properties. Being aware of this, we decided to improve the ligand-free modification method of OA-capped NaYF4:Yb3+,Er3+/NaYF4 UCNPs prepared by precipitation in high-boiling-point solvents as the thus-far reported methods do not provide satisfactory results. Different molarities of hydrochloric acid and various mixing times were selected to remove the organic ligand from the NPs’ surface and to discover the most promising modification approach. Highly water-stable colloids were obtained with a very high reaction yield of up to 96%. Moreover, the acid treatment did not affect the morphology and the size of the product. All of the crystals exhibited a bright up-conversion emission under 975-nm excitation, which confirmed the two-photon excitation and effective energy transfer between the used dopant ions. Thus, we could establish the most successful ligand-free modification procedure.