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Abstract Solid refrigerants exhibiting a caloric effect upon applying external stimuli are receiving attention as one of the next-generation refrigeration technologies. Herein, we report a new inorganic refrigerant, rubidium cyano-bridged manganese–iron–cobalt ternary metal assembly (cyano-RbMnFeCo). Cyano-RbMnFeCo shows a reversible barocaloric effect with large reversible adiabatic temperature changes of 74 K (from 57 °C to −17 °C) at 340 MPa, and 85 K (from 88 °C to 3 °C) at 560 MPa. Such large reversible adiabatic temperature changes have yet to be reported among caloric effects in solid–solid phase transition refrigerants. The reversible refrigerant capacity is 26000 J kg−1 and the temperature window is 142 K. Additionally, cyano-RbMnFeCo shows barocaloric effects even at low pressures, e.g., reversible adiabatic temperature change is 21 K at 90 MPa. Furthermore, direct measurement of the temperature change using a thermocouple shows +44 K by applying pressure. The temperature increase and decrease upon pressure application and release are repeated over 100 cycles without any degradation of the performance. This material series also possesses a high thermal conductivity value of 20.4 W m−1 K−1. The present barocaloric material may realize a high-efficiency solid refrigerant.

Understanding the mechanism of supercooling suppression by crystallization seeds is important for designing semiclathrate hydrates for latent heat storage materials. Here, we show that 10-30 nm cluster formation around silver nanoparticles promotes crystallization of supercooled aqueous solutions.

Electron spin resonance (ESR) spectra of butyl radicals induced with γ-ray irradiation in the simple isobutane (2-methylpropane) hydrate (prepared with deuterated water) were investigated. Isothermal annealing results of the γ-ray-irradiated isobutane hydrate reveal that the isobutyl radical in a large cage withdraws a hydrogen atom from the isobutane molecule through shared hexagonal-faces of adjacent large cages. During this “hydrogen picking” process, the isobutyl radical is apparently transformed into a tert-butyl radical, while the sum of isobutyl and tert-butyl radicals remains constant. The apparent transformation from isobutyl to tert-butyl radicals is an irreversible first-order reaction and the activation energy was estimated to be 35 ± 3 kJ/mol, which was in agreement with the activation energy (39 ± 5 kJ/mol) of hydrogen picking in the γ-ray-irradiated propane hydrate with deuterated water.

The equilibrium pressure-temperature relations of the tetra-n-butyl ammonium bromide (TBAB) semiclathrate hydrate were measured at pressures of up to 80 MPa by high-pressure differential scanning calorimetry. As a pressurizing medium, tetrafluoromethane (CF4), which cannot occupy any hydrate cages in the TBAB semiclathrate hydrate at the present experimental pressures, was used. The dissociation temperature of tetragonal TBAB semiclathrate hydrate (TBAB·26H2O) increases with the increase in pressure, whereas the dissociation enthalpy is (192 ± 3) J·g-1 and almost constant at pressures of up to 80 MPa. The temperature difference between formation and dissociation at the same pressure, that is, the maximum allowable degree of supercooling, is (17.7 ± 0.7) K and independent of the pressure. [ABSTRACT FROM AUTHOR]

Thermodynamic stability boundaries of xenon (Xe) + benzene mixed hydrate system were measured in a temperature range of (274.1 to 284.4) K and pressure range up to 0.5 MPa. The four-phase equilibrium curve of structure-II hydrate (HsII), aqueous (Lw), C6H6-rich liquid (LHC), and gas (G) phases in the Xe+benzene mixed hydrate system intersects with the three-phase equilibrium curve (HsI+Lw+G) in the structure-I simple Xe hydrate system. The slope of HsII+Lw+LHC+G in the Xe+benzene mixed hydrate system changes around (283.00 ± 0.05) K and (0.420 ± 0.005) MPa. At temperatures above 283.00 K, the structure-II Xe+benzene mixed hydrate collapses and instead, the structure-I simple Xe hydrate is formed. [ABSTRACT FROM AUTHOR]

High-pressure phase equilibrium relations of the 1,1-difluoroethane (HFC-152a) water binary system were investigated in a temperature range of (275.03 to 319.30) K and a pressure range up to 370 MPa. Four three-phase coexisting curves of hydrate aqueous gas phases, hydrate HFC-152a-rich liquid gas phases, hydrate aqueous HFC-152a-rich liquid phases, and aqueous HFC-152a-rich liquid gas phases originate from the quadruple point of hydrate aqueous HFC-152a-rich liquid HFC-152a gas phases located at (288.05 ± 0.15) K and (0.44 ± 0.01) MPa. The structure of HFC-152a hydrate remains structure I (s-I) in the pressure range up to 370 MPa. Raman spectra of the HFC-152a molecule in the HFC-152a hydrate indicate that the HFC-152a molecules occupy only large cages of s-I HFC-152a hydrate in the presence of completely vacant small cages at a pressure up to 370 MPa. [ABSTRACT FROM AUTHOR]

Binary clathrate hydrates with methane (CH4, 4.36 Å) and tert-butylamine (t-BuNH2, 6.72 Å) as guest molecules were synthesized at different molar concentrations of t-BuNH2(1.00−9.31 mol %) with methane at 7.0 MPa and 250 K, and were characterized by powder X-ray diffraction (PXRD) and Raman microscopy. A structural transformation from sVI to sII of t-BuNH2hydrate was clearly observed on pressurizing with methane. The PXRD showed sII signatures and the remnant sVI signatures were insignificant, implying the metastable nature of sVI binary hydrates. Raman spectroscopic data on these binary hydrates suggest that the methane molecules occupy the small cages and vacant large cages. The methane storage capacity in this system was nearly doubled to ∼6.86 wt % for 5.56 mol % > t-BuNH2> 1.0 mol %. [ABSTRACT FROM AUTHOR]

The first proof-of-concept of the formation of a double tert-butylamine (t-BuNH2) + hydrogen (H2) clathrate hydrate has been demonstrated. Binary clathrate hydrates with different molar concentrations of the large guest t-BuNH2(0.98−9.31 mol %) were synthesized at 13.8 MPa and 250 K, and characterized by powder X-ray diffraction and Raman microscopy. A structural transformation from sVI to sII of t-BuNH2hydrate was clearly observed under hydrogen pressures. Raman spectroscopic data suggested that the hydrogen molecules occupied the small cages and had similar occupancy to hydrogen in the double tetrahydrofuran (THF) + H2clathrate hydrate. The hydrogen storage capacity in this system was ∼0.7 H2wt % at the molar concentration of t-BuNH2close to the sII stoichiometry. [ABSTRACT FROM AUTHOR]

Phase equilibria (pressure−temperature relations) of the H2tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2and tetrahydrofuran for the H2tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution. [ABSTRACT FROM AUTHOR]

Thermodynamic stability boundaries of nitrous oxide (N2O) hydrate and Raman spectra of the N2O and host water molecules in the N2O hydrate system were investigated in a temperature range of (275.20 to 298.19) K and a pressure range up to 305 MPa. Two three-phase coexisting curves of (hydrate + aqueous + gas) and (hydrate + aqueous + liquid N2O) originate from the quadruple point of (hydrate + aqueous + liquid N2O + gas) located at (285.15 ± 0.05) K and (4.2 ± 0.1) MPa. The phase behavior of the N2O hydrate system is similar to that of the carbon dioxide (CO2) hydrate system up to 100 MPa, while the stability boundaries of the N2O hydrate system are shifted parallel to the (2 to 3) K higher temperature side than that of CO2hydrate. Raman peak splitting of the intramolecular vibration mode for the nitrous oxide molecule in the hydrate phase indicates the occupancy of the nitrous oxide molecule in both small and large cages of structure-I, and this observation is also corroborated by the pressure-induced Raman shift of the lattice mode. [ABSTRACT FROM AUTHOR]

Electron spin resonance measurement of gamma-ray-irradiated propane hydrates shows that the normal propyl radical withdraws hydrogen from the adjacent propane molecule through the hexagonal planes of the hydrate cage without water molecule bridging. [ABSTRACT FROM AUTHOR]

A 61-year-old woman presented to the gynecology department with complaints of atypical genital bleeding. Magnetic resonance imaging revealed a localized urethral tumor extended to vagina. Histological test of the biopsy tissue of the mass suggested the adenocarcinoma. The patientwas performed the fenestration of the anterior vaginalwall 15 years ago. Under the diagnosis of urethral diverticular adenocarcinoma, we performed standard open total cystectomy with lymph node excision and ileal conduit.We could not establish a diagnosis of urethral diverticulum from the histological test; however, we clinically diagnosed as urethral diverticular adenocarcinoma. Because carcinoma arising from urethral diverticula is reported, a close long-term follow-up for the recurrence or generation of malignant tumors by genitourinary examinations or images is necessary, for the patient with urethral diverticula. [ABSTRACT FROM AUTHOR]