Pressure-induced transformations in LiCl–H2O at 77 K

A systematic study of the properties of high-density amorphous ice (HDA) in the presence of increasing amounts of salt is missing, especially because it is challenging to avoid ice crystallization upon cooling the pressurized liquid. In order to be able to study HDA also in the presence of small amounts of salt, we have investigated the transformation behaviour of quenched aqueous LiCl solutions (mole fraction x 1 GPa. The observed densification is consistent with the idea that a freeze concentrated LiCl solution of x = 0.14 (R = 6) segregates, which transforms to the glassy state upon cooling, and that the densification is only due to the Ih → HDA transition. Also the XRD patterns and DSC scans are almost unaffected by the presence of the segregated glassy LiCl solution. Upon heating at ambient pressure HDA experiences the polyamorphic transition to low-density amorphous ice (LDA) at ∼120 K, even at x ∼ 0.10. Based on the latent heat evolved in the transition we suggest that almost all water in the sample transforms to an LDA-like state, even the water in the vicinity of the ions. The glassy LiCl solution acts as a spectator that does not shift the transformation temperature significantly and experiences a glass-to-liquid transition at ∼140 K prior to the crystallization to cubic ice. By contrast, at x > 0.12 the phenomenology completely changes and is now dominated by the salt. Hexagonal ice no longer forms upon quenching the LiCl solution, but instead LDA forms. A broad pressure-induced transformation at >0.6 GPa can be attributed to the densification of LDA, the glassy LiCl solution and/or glassy hydrates.Fil: Ruiz, G. N.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Innsbruck; AustriaFil: Bove, L. E.. Universite Pierre et Marie Curie; Francia. Ecole Polytechnique Federale de Lausanne; SuizaFil: Corti, Horacio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Loerting, T.. Universidad de Innsbruck; Austri

Observation of a nanophase segregation in LiCl aqueous solutions from Transient Grating Experiments

Transient Grating experiments performed on supercooled LiCl, RH2O solutions with R>6 reveal the existence of a strong, short time, extra signal which superposes to the normal signal observed for the R=6 solution and other glass forming systems. This extra signal shows up below 190 K, its shape and the associated timescale depend only on temperature, while its intensity increases with R. We show that the origin of this signal is a phase separation between clusters with a low solute concentration and the remaining, more concentrated, solution. Our analysis demonstrates that these clusters have a nanometer size and a composition which are rather temperature independent, while increasing R simply increases the number of these clusters.Comment: 19 pages+ 8 figures+ 2 table

Efficient heating of sanitary water with heat pump

This work presents a thermal and economical assessment about replacing the conventional household water heater (electrical, 100 % efficiency) by a modern heat pump water heater, which efficiency is proportional to the outdoor temperature, but about three and five times higher than the previous one. Thus, the efficiency calculated for capitals of Latin-American countries has obtained average values ranging from 298 % to 434 %. However, the payback period obtained is also related to the electricity tariff and the temperature of the cold-water grid, which varies from 0.064 US$/kWh in Paraguay to 0.233 US$/kWh in Costa Rica, and from 10 °C (La Paz) to 26.8 °C (Costa Rica). Thus, a ranking of payback period (replacing/new installation) was performed for an average consumption of a five-person family, obtaining values ranging from 2.4/1.4 years (Montevideo) to 10.5/6.1 years (Asunción), and also it was calculated the energy annual saving obtaining from 1,436 kWh (Costa Rica) to 2,660 kWh (La Paz). Thus, we have found great potential for household energy saving in Latin-American countries by substituting the conventional water heater by a modern heat pump.Se presenta un análisis térmico-económico sobre la sustitución del termotanque hogareño convencional por una bomba de calor, cuya eficiencia es varias veces mayor. Así, la eficiencia promedio calculada en las capitales de países latinoamericanos varía del 298% al 434%. Sin embargo, y como será analizado, el período de repago obtenido depende también de la tarifa eléctrica y de la temperatura del agua fría de red, yendo desde 0.064 US$/kWh (Paraguay) hasta 0.233 US$/kWh (Costa Rica), y desde 10 °C (La Paz) hasta 26.8 °C (Costa Rica). Para una familia promedio de 5 personas se calculó un ranking (recambio/nuevo) con períodos de repago que van de 2.4/1.4 años (Montevideo) a 10.5/6,1 años (Asunción); además, se calculó el ahorro anual de energía, desde 1,436 kWh (Costa Rica) hasta 2,660 kWh (La Paz). Así, hemos encontrado un gran potencial de ahorro energético en los hogares de los países latinoamericanos al sustituir el calentador de agua convencional por una bomba de calor

Calorimetric study of water's two glass transitions in the presence of LiCl

A DSC study of dilute glassy LiCl aqueous solutions in the water-dominated regime provides direct evidence of a glass-to-liquid transition in expanded high density amorphous (eHDA)-type solutions. Similarly, low density amorphous ice (LDA) exhibits a glass transition prior to crystallization to ice Ic. Both glass transition temperatures are independent of the salt concentration, whereas the magnitude of the heat capacity increase differs. By contrast to pure water, the glass transition endpoint for LDA can be accessed in LiCl aqueous solutions above 0.01 mole fraction. Furthermore, we also reveal the endpoint for HDA's glass transition, solving the question on the width of both glass transitions. This suggests that both equilibrated HDL and LDL can be accessed in dilute LiCl solutions, supporting the liquid-liquid transition scenario to understand water's anomalies.Fil: Ruiz, Guadalupe N.. Universidad de Innsbruck; Austria. Universidad Politécnica de Catalunya; EspañaFil: Amann Winkel, Katrin. AlbaNova University Center; Suecia. Universidad de Innsbruck; AustriaFil: Bove, Livia E.. Université Pierre et Marie Curie; FranciaFil: Corti, Horacio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad de Buenos Aires; ArgentinaFil: Loerting, Thomas. Universidad de Innsbruck; Austri

Recent finding and new technologies in nephrolithiasis: a review of the recent literature

This review summarizes recent literature on advances regarding renal and ureteral calculi, with particular focus in areas of recent advances in the overall field of urolithiasis. Clinical management in everyday practice requires a complete understanding of the issues regarding metabolic evaluation and subgrouping of stone-forming patients, diagnostic procedures, effective treatment regime in acute stone colic, medical expulsive therapy, and active stone removal. In this review we focus on new perspectives in managing nephrolitihiasis and discuss recentadvances, including medical expulsive therapy, new technologies, and refinements of classical therapy such as shock wave lithotripsy, give a fundamental modification of nephrolithiasis management. Overall, this field appears to be the most promising, capable of new developments in ureterorenoscopy and percutaneous approaches. Further improvements are expected from robotic-assisted procedures, such as flexible robotics in ureterorenoscopy

Ergodicity breaking in strong and network-forming glassy system

The temperature dependence of the non-ergodicity factor of vitreous GeO$_2$, $f_{q}(T)$, as deduced from elastic and quasi-elastic neutron scattering experiments, is analyzed. The data are collected in a wide range of temperatures from the glassy phase, up to the glass transition temperature, and well above into the undercooled liquid state. Notwithstanding the investigated system is classified as prototype of strong glass, it is found that the temperature- and the $q$-behavior of $f_{q}(T)$ follow some of the predictions of Mode Coupling Theory. The experimental data support the hypothesis of the existence of an ergodic to non-ergodic transition occurring also in network forming glassy systems

Effect of Polyethylene Glycol Treatment on Acetic Acid Emissions from Wood

Acetic acid is known to be emitted from sound wood and can accelerate damage to heritage materials, particularly metals. However, few studies have investigated the extent of acetic acid emissions from archaeological wood. This research utilised Solid-Phase-Micro-Extraction (SPME) GC–MS and lead coupon corrosion to identify volatile emissions from polyethylene glycol (PEG)-treated archaeological wood from the Mary Rose collection and assess if they could cause accelerated damage. In addition, the effect of PEG treatment on acetic acid emissions was investigated using sound wood samples. For sound wood, the PEG treatment acted as a barrier to acetic acid emissions, with higher-molecular-weight PEGs preventing more emissions. Archaeological wood, despite its age and high-molecular-weight PEG treatment, still emitted detectable concentrations of acetic acid. Moreover, they emitted a wider array of compounds compared to sound wood, including carbon disulphide. Like sound wood, when the archaeological wood samples were in a sealed environment with lead coupons, they caused accelerated corrosion to lead. This evidences that archaeological wood can emit high enough concentrations of volatile compounds to cause damage and further investigation should be performed to evaluate if this can occur inside museum display cases