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The purpose of this study was to compare patency and nonabandonment rates for second percutaneous transluminal angioplasty (PTA) and surgical reconstruction for the treatment of failing vascular access due to restenosis or reocclusion in a short time after initial PTA.Seventy two consecutive patients who underwent second treatment within 90 days after the initial PTA were evaluated retrospectively. The patency (time to corrective procedure) and access abandonment were compared among patients who underwent a second PTA (n = 35) and those who underwent surgical reconstruction (n = 37). Univariate and multivariate analyses were performed to determine independent predictors of patency and access abandonment at 1 year after the treatment.At 1 year after the treatment, the patency rates were 35.1% and 11.4% (P = 0.02) and nonabandonment rates were 64.9% and 77.1% (P = 0.25) for surgical reconstruction and second PTA, respectively. The Kaplan-Meier survival analysis showed that the surgical reconstruction group had better patency probability (P = 0.02), but there was no difference in the nonabandonment probability between the groups (P = 0.29). Shorter time to retreatment was associated with good patency. The female gender was likely to be associated with access abandonment.The access abandonment between the 2 procedures had no difference, although surgical reconstruction provided better patency than second PTA.

Reproduced from New J. Chem., 2023, 47, 231-237 with permission from the Royal Society of Chemistry., https://doi.org/10.1039/d2nj04361k, Ionic clathrate hydrates (ICHs) have been applied to thermal storage materials, which can be utilized as unusual thermal energy sources. In the present study, we developed a novel ICH including tri-n-butyl(cyclobutylmethyl)phosphonium bromide (P444(1c4)-Br) as an unprecedented guest species. The highest equilibrium temperature and the dissociation enthalpy of P444(1c4)-Br ICH were 279.5 ± 0.1 K and 202 ± 2 J g−1, respectively, at the mole fraction of 0.0255 ± 0.0008. The highest equilibrium temperature of P444(1c4)-Br ICH was slightly lower than that of the tetra-n-butylphosphonium bromide (P4444-Br) ICH. The dissociation enthalpy of P444(1c4)-Br ICH was larger than that of other ICHs with similar highest equilibrium temperatures. Cyclic hydrocarbon groups, together with normal, branched, saturated, and unsaturated hydrocarbon chains, can be one of the options for tuning the equilibrium temperature of ICHs.

Azuma S., Shimada J., Tsunashima K., et al. Equilibrium Phase Relations and Dissociation Enthalpies of Tri- n-butylalkenylphosphonium Bromide Semiclathrate Hydrates. Journal of Chemical and Engineering Data, 67, 6, 1415 - 1420, May 25, 2022, © 2022 American Chemical Society. https://doi.org/10.1021/acs.jced.2c00146., Semiclathrate hydrates (SCHs) have received attention as thermal storage materials because of their equilibrium temperature and relatively large dissociation enthalpy. The alkyl length of quaternary onium cations significantly affects the equilibrium temperature and dissociation enthalpy of quaternary onium salt SCHs. To investigate the effects of the double bond introduced in onium cations, in the present study, the thermodynamic stability of tri-n-butylalkenylphosphonium bromide (P444(alkenyl)-Br: alkenyl = 3-butenyl (3═1) or 4-pentenyl (4═1)) SCH was investigated. The equilibrium temperatures and the dissociation enthalpies were determined to be (277.5 ± 0.1) K and (199 ± 2) J/g for P444(3═1)-Br SCH, and (274.8 ± 0.1) K and (188 ± 2) J/g for P444(4═1)-Br SCH. The equilibrium temperatures of P444(3═1)-Br SCH and P444(4═1)-Br SCH were lower than those of the corresponding normal alkyl SCHs (P4444-Br and P4445-Br), although the equilibrium temperature of tri-n-butylallylphosphonium bromide SCH was higher than that of the P4443-Br SCH.

We found that an AAA-type battery (min. 750 mAh) pressurized with Ar or N2 at pressures of up to 5 MPa exhibited a significant durability enhancement even under high-current conditions.

The addition of silver(ii) oxide effectively diminishes the degree of supercooling in the tetrahydrofuran hydrate formation.

Jin Shimada, Moe Yamada, Atsushi Tani et al. Thermodynamic Properties of Tetra-n-butylphosphonium Dicarboxylate Semiclathrate Hydrates. Journal of Chemical & Engineering Data, 67 (1), 67-73, January 13, © 2022 American Chemical Society. https://doi.org/10.1021/acs.jced.1c00741, Semiclathrate hydrate (SCH) is one of the phase change materials suitable for cold energy storage. Thermodynamic properties of SCHs, such as an equilibrium temperature and the dissociation enthalpy, depend on the size and shape of the guest substances. In the present study, to reveal the effects of steric conformations of the guest anions on the thermodynamic properties of SCHs, tetra-n-butylphosphonium dicarboxylate (TBP-DC) SCHs, where the anion was oxalate (TBP-Oxa), malonate (TBP-Mal), succinate (TBP-Suc), glutarate (TBP-Glu), maleate (TBP-Male), or fumarate (TBP-Fum), were investigated. TBP-Oxa, -Mal, -Suc, and -Fum SCHs had similar equilibrium temperatures, whereas the equilibrium temperatures of TBP-Glu and -Male SCHs were higher. This suggests that the size and conformation of glutarate and maleate anions are appropriate for the cage structures of SCHs. Moreover, we compared the equilibrium temperatures of TBP-Suc, -Male, and -Fum SCHs because TBP-Suc, -Male, and -Fum have similar anion structures. The equilibrium temperature of TBP-Suc SCH was similar to that of TBP-Fum SCH, whereas TBP-Male SCH showed a higher equilibrium temperature. This result implies that the succinate anion is accommodated in the trans conformation, similar to the fumarate anion, in the hydrate cages.

Clathrate hydrate as well as ice has been spotlighted as promising materials to investigate the properties of hydrogen-bonded networks formed by the water molecules. In the semiclathrate hydrate (SCH, a kind of clathrate hydrate) consisting of host water molecules and guest quaternary onium salts, the anion takes part in the hydrogen-bonded networks with the water molecules. In the present study, we measured the electrical conductivity and electrical relaxation time in the single-crystalline tetra-n-butylammonium bromide (TBAB) SCH by electrochemical impedance spectroscopy. The results clearly revealed that the conduction carrier was proton. The electrical relaxation time of proton conduction in TBAB SCH was similar to the reorientation time of the water molecules in TBAB SCH estimated by the results of nuclear magnetic resonance.

Phase equilibrium (temperature–composition) relations of the tetra-n-butylphosphonium trifluoroacetate (TBP-TFA) + water binary system including solid (semiclathrate hydrate, SCH)-liquid equilibria and liquid-liquid equilibria were investigated. Phase diagram of TBP-TFA SCH exhibited peritectic behavior. The maximum decomposition temperature (peritectic temperature) of TBP-TFA SCH at atmospheric pressure were 275.9 ± 0.1 K. The stoichiometric composition of TBP-TFA SCH was located at the mole fraction of 0.027 ± 0.002. The decomposition enthalpy of TBP-TFA SCH was 199 ± 2 J/g. At temperatures above the lower critical solution temperature (LCST), the liquid-liquid phase separation appeared. Interestingly, the composition at the LCST was 0.026 ± 0.002, which is very similar to the stoichiometric composition of TBP-TFA SCH. It implies that both cluster-based solution structures are similar.

Thermodynamic stabilities of tetra-n-butylphosphonium acetate (TBP-Ace) semiclathrate hydrates in the presence of methane (CH 4 ), carbon dioxide (CO 2 ), nitrogen (N 2 ), or ethane (C 2 H 6 ) were measured in a pressure range up to approximately 5 MPa. The dissociation temperature of TBP-Ace + CH 4 , TBP-Ace + CO 2 , and TBP-Ace + N 2 semiclathrate hydrates increased drastically with an increase in pressure, which means that CH 4 , CO 2 , and N 2 molecules occupy the vacant cages of the TBP-Ace semiclathrate hydrate. On the other hand, the C 2 H 6 molecules hardly occupied the cages, resulting in small pressure dependence of the dissociation temperature. Raman spectra and powder X-ray diffraction patterns of TBP-Ace + CO 2 semiclathrate hydrate reveal that the phase transition occurs at 1.04 ± 0.04 MPa and 285.88 ± 0.05 K. One of the possible reasons why the phase transition occurs is that the carbonate and/or hydrogen carbonate anions derived from the CO 2 molecules are replaced with some of acetate anions in the TBP-Ace + CO 2 semiclathrate hydrate.

Nano-sized metal particles have been actively investigated. Although the synthesis methods of nano-sized metal particles have been made remarkable progress through many researches, in many cases, heat treatment is required. In order to promote industrial utilization, non-heating, simple and inexpensive synthesis methods are required. In the present study, nano-sized metal particles composed of Ag, Au, Ir, or Pd were prepared in an aqueous solution with a simple and non-heating way. After a noble-metal carboxylate was completely dissolved in the quaternary ammonium carboxylate aqueous solution, nanoparticles composed of the noble metal appeared in the aqueous solution. Since this operation is extremely simple as well as non-heating because the noble-metal carboxylate only dissolves into the quaternary ammonium carboxylate aqueous solution. The nano-sized metal particles were observed by Scanning Electron Microscope (SEM) or Scanning Transmission Electron Microscope (STEM) with the freeze-fracture replica method and characterized with Energy Dispersive X-ray Spectroscopy (EDX) and Electron Energy Loss Spectroscopy (EELS).

This paper reports phase equilibrium (temperature–composition) relations of semiclathrate hydrates formed from tetra-n-butylphosphonium propionate (TBP-Pro) and butyrate (TBP-But) + water systems. Their maximum solid–liquid phase equilibrium temperatures at atmospheric pressure were located at (288.75 ± 0.06) K and the mole fraction x1 = 0.035 ± 0.001 and (287.01 ± 0.06) K and x1 = 0.028 ± 0.001, respectively. They showed equilibrium temperatures higher than those of tetra-n-butylphosphonium formate, acetate, and lactate semiclathrate hydrates. The dissociation enthalpies of TBP-Pro and TBP-But semiclathrate hydrates were (190 ± 5) J·g−1 and (204 ± 5) J·g−1, respectively. The temperature difference between formation and dissociation, that is, the maximum allowable degree of supercooling, was (17.7 ± 1.5) K for TBP-Pro semiclathrate hydrate and (15.4 ± 1.4) K for TBP-But one.

Type A acute aortic dissection (TAAAD) carries a high mortality rate in the absence of surgical treatment. This study sought to determine whether combining the assessment of clinical and computed tomography (CT) findings can be used to predict the long-term all-cause mortality rate of patients with TAAAD. Eighty-five consecutive patients with TAAAD who had undergone CT imaging and surgery were retrospectively reviewed. For the clinical and CT findings, univariate testing followed by multivariate logistic regression analysis was conducted to identify independent predictors of death. Then, the area under the receiver operating characteristic curve of the combined prediction model was calculated. The long-term mortality rate was 34.1% in our cohort (a median follow-up period of 60 months). Multivariate logistic regression analysis identified the following presenting variables as predictors of death: male sex (odds ratio [OR]: 6.67; 95% confidence interval [CI]: 1.67–25.0; P = .007), kidney malperfusion (OR: 2.18; 95% CI: 1.16–4.1; P = .02), and descending aorta size (OR: 1.12; 95% CI: 1.00–1.25; P = .05). Receiver operating characteristic curve analysis revealed an area under the receiver operating characteristic curve of 0.84 when using the combined model for prediction of long-term all-cause mortality (P ≤ .01). The combined assessment of clinical and CT findings can reasonably predict the long-term prognosis of TAAAD with surgery.

As a guest molecule of urea clathrate, a long-chain normal alkane and its derivative with low substituents in methanol solutions have been reported. To investigate the role of methanol in the urea clathrate formation, in the present study, we used propane (C3H8), propylene (C3H6), ethane (C2H6), and methane (CH4) as guest molecules. Raman spectra and powder X-ray diffraction profiles revealed that, regardless of the existence of methanol, the C3H8, C3H6, and C2H6 molecules are enclathrated into urea clathrates with a hexagonal structure, whereas there is no urea clathrate formation enclathrating CH4. The pressurization of the urea clathrates including C2H6 and C3H8 reveals that no pressure-induced structural phase transition occurs at pressures up to 200 MPa. In spite of the guest molecule much shorter than the lattice constant of the c-axis of the hexagonal channel structure, the urea clathrates have a fairly rigid structure against the compression. Methanol as an auxiliary solution is not always necessary for the urea clathrate formation. Methanol plays a role in decreasing the activation energy of the urea clathrate formation, although it makes urea clathrate thermodynamically unstable due to the high solubility of urea in methanol.

Phase equilibrium (temperature–composition) relations of tetra-n-butylphosphonium formate (TBP-For), acetate (TBP-Ace), and lactate (TBP-Lac) semiclathrate hydrate systems have been measured. The highest equilibrium temperatures of TBP-For, TBP-Ace, and TBP-Lac semiclathrate hydrates were 280.9, 284.6, and 283.8 K at the atmospheric pressure, respectively, where the composition of tetra-n-butylphosphonium carboxylate was approximately 0.035 ± 0.001 (mole fraction) in every system. The dissociation enthalpies of tetra-n-butylphosphonium carboxylate semiclathrate hydrates were measured by differential scanning calorimetry. The dissociation enthalpies of TBP-For, TBP-Ace, and TBP-Lac semiclathrate hydrates were (187 ± 3), (193 ± 3), and (177 ± 3) J·g–1, respectively.

A large degree of supercooling is necessary to form the tetra-n-butyl ammonium bromide (TBAB) semiclathrate hydrate. One of the effective methods to suppress supercooling is the utilization of a kind of hysteresis called the “memory effect”. Generally, the memory effect reduces supercooling and/or the induction period in clathrate hydrate formation. In the present study, we have observed the solution structure of TBAB aqueous solutions in the formation and decomposition processes of TBAB semiclathrate hydrate by scanning electron microscopy (SEM) with the freeze-fracture replica method. The relationship between the memory effect and the solution structures of the TBAB supercooled aqueous solution was elucidated. The memory effect in the TBAB semiclathrate hydrate reformation is derived from the existence of residual clusters of 10–20 nm in the TBAB aqueous solution at 286.2 K, which is 1.0 K higher than the equilibrium decomposition temperature, even after the TBAB semiclathrate hydrate was completely decomposed.

Semiclathrate hydrate (SCH) is one of the phase change materials suitable for cold storage. The thermodynamic properties of SCHs, such as an equilibrium temperature and a dissociation enthalpy, depend on the size and shape of guest substances. In this study, to reveal the effect of cation size and shape on the thermodynamic properties, tri-n-butylalkylphosphonium bromide (P444R-Br) SCHs, where the alkyl group was n-propyl (R = 3), n-butyl (R = 4), n-pentyl (R = 5), i-butyl (R = i-4), i-pentyl (R = i-5), or allyl (R = Al)), were investigated. The branched alkyl groups (R = i-4 or i-5) raised the equilibrium temperature, whereas the shorter alkyl groups (R = 3 or Al) lowered one. Except for P4445-Br and P444(Al)-Br SCHs, the other P444R-Br SCHs had the same orthorhombic structure. Among the orthorhombic systems in the present study, the semiclathrate hydrate with a higher equilibrium temperature had a larger dissociation enthalpy.

We have observed the solution structure of the supercooled sodium acetate aqueous solution, especially for the existence of clusters and their crystallization process, by means of Scanning electron microscopy (SEM) with the freeze replica method. Microscopic internal structure of sodium acetate trihydrate crystals mainly constitutes the aggregates of 100–200 nm in diameter, which consists of the clusters of 10–20 nm in diameter. In the case of a supercooled aqueous solution of 293 K, two types of aspect in the vitrified aqueous solution mainly exist: one is the clusters of 10–20 nm in diameter; the other is the smooth zone without any structure. At 263 K, the relationship among clusters of 10–20 nm and their aggregates of 100–200 nm was clearly observed. The aggregates construct the three-dimensional loose networks, which are not fully packed, different from the crystal.

Takeshi Sugahara and Hironobu Machida. Dissociation and Nucleation of Tetra-n-butyl Ammonium Bromide Semi-Clathrate Hydrates at High Pressures. Journal of Chemical & Engineering Data, 62 (9), 2721–2725, September 14, © 2017 American Chemical Society. https://doi.org/10.1021/acs.jced.7b00115, 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.

Takeshi Sugahara. Four-phase equilibrium relations including clathrate hydrate phase in a ternary system of xenon, benzene, and water. Journal of Chemical & Engineering Data, 61 (12), 4057–4060, December 8, © 2016 American Chemical Society. https://doi.org/10.1021/acs.jced.6b00541, 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.

The three-phase equilibrium curves of hydrate, aqueous, and gas phases in the ternary system of ethane (C 2 H 6 ), ammonium bromide (NH 4 Br), and water were measured at pressures up to 3 MPa and temperatures of 278.45–283.76 K. The phase equilibrium curves exhibit two trends; the curve paralleled with that of simple C 2 H 6 hydrate and the one steeper than that of simple C 2 H 6 hydrate. The latter implies the incorporation of NH 4 Br into C 2 H 6 hydrate while the former indicates the thermodynamic inhibition effect of NH 4 Br. To investigate the incorporation of NH 4 Br, Raman spectra of the N–H stretching vibration of NH 4 + were analyzed. Raman spectra imply the existence of the motionally restricted NH 4 + in the formed hydrate. Both results from the phase behavior and Raman spectra imply the formation of C 2 H 6 + NH 4 Br semi-clathrate hydrates.

Density functional theory is used to calculate the vacancy stability and its effect on oxygen trapping and diffusion behavior in Cr- and Ti-doped nickel bulks. The calculated results show that doping of Ti and Cr has an attractive interaction with a monovacancy from the first nearest neighbor to the third nearest neighbor position. The oxygen insertion energy of the nickel perfect lattice is significantly lower than that of the doped structures. It reveals that an oxygen atom can be strongly trapped near the alloying element. A monovacancy can strongly bind with an oxygen atom, and the alloying element does not change the binding energy. The presence of Ti and Cr reduces the number of oxygen atoms, leading to a decrease in oxygen content. The overall activation energy of oxygen is increased by a monovacancy and an alloying element, which may reduce the oxygen diffusivity in the structures.

The solution structures in the tetra-n-butylammonium bromide (TBAB) aqueous solution relate closely with the memory effect. In the present study, the behavior derived from the existence of the residual solution structures after TBAB semiclathrate hydrate (TBAB SCH) decomposition was investigated with two methods. One is a high-precision differential scanning calorimetry. The heat capacity of a TBAB aqueous solution with memory effect was slightly larger than that after the memory effect disappeared. The larger heat capacity implies the existence of solution structures. The other is a small-angle X-ray scattering (SAXS). In the first cooling process, strong scattering derived from rapid crystallization was observed at 263.6 K. In the second cooling process where the TBAB aqueous solution exhibited the memory effect, the scattering intensity gradually increased and became remarkably strong at a temperature (approximately 277 K) higher than 263.6 K. In the second cooling process, the invariant Q, which corresponds to electron density fluctuation, increased gradually until crystallization, whereas, in the first cooling process, the change of the invariant Q was quite small until crystallization. The increase of invariant Q implies the existence of 10–100 nm density fluctuation, which is consistent with the cluster size (10–20 nm) previously observed with electron microscopy in the same system.

Purpose Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common encephalopathy subtype in Japanese children. Few case reports have shown perfusion abnormality on arterial spin labeling (ASL) in patients with AESD. The present study aimed to review the chronological change of cerebral perfusion on three-dimensional (3D) ASL in patients with AESD. Methods Twenty consecutive patients with AESD were enrolled; the patients underwent MRI including 3D ASL. The clinical course of AESD was divided into four phases according to the time from occurrence of seizures to MRI. Two neuroradiologists independently assessed presence or absence, distribution, and severity of perfusion abnormality using ASL and qualitatively scored perfusion abnormality using a five-point grading system. The level of interobserver agreement in the evaluation was analyzed using weighted κ statistics. Additionally, the signal ratio of abnormal perfusion region and peri-central sulcus region on ASL was semi-quantitatively evaluated. Moreover, we qualitatively compared the distribution between perfusion abnormality on ASL and bright tree appearance (BTA) on diffusion-weighted image (DWI). Results ASL showed hypoperfusion from 8.5 to 22 h after early seizures (ESs) and hyperperfusion within 24 h after late seizures (LSs). Various perfusions were found >3 days after LSs. Interobserver agreement for qualitative scored perfusion abnormality was good (κ = 0.77). The distribution of abnormal perfusion was relatively consistent with BTA. Conclusion In AESD, cerebral perfusion changes with time. ASL showed hypoperfusion from 8.5 to 22 h after ESs, hyperperfusion within 24 h after LSs in patients with AESD.

Solid-state refrigeration technology based on caloric effects are promising to replace the currently used vapor compression cycles. However, their application is restricted due to limited performances of caloric materials. Here, we have identified colossal barocaloric effects (CBCEs) in a class of disordered solids called plastic crystals. The obtained entropy changes are about 380 J kg-1 K-1 in the representative neopentylglycol around room temperature. Inelastic neutron scattering reveals that the CBCEs in plastic crystals are attributed to the combination of the vast molecular orientational disorder, giant compressibility, and high anharmonic lattice dynamics. Our study establishes the microscopic scenario for CBCEs in plastic crystals and paves a new route to the next-generation solid-state refrigeration technology., Comment: four figures and supplementary materials

Earthquakes are unpredictable and inevitable disasters, causing various earthquake-related disorders. Medical imaging, including digital radiography, computed tomography, and magnetic resonance imaging, plays a key role in the evaluation of earthquake-related disorders. We here demonstrate the concept of diagnostic imaging after a massive earthquake and review the common imaging features of various disorders in casualties and evacuees. This summary of imaging features can facilitate the diagnosis of various earthquake-related disorders and promote judicious therapy planning.

Clathrate hydrates preserve active species more stably than the other icy materials and investigation of the behavior of the active species elucidates the physicochemical properties of clathrate hydrates like guest-guest interaction. Color of the tert-butylamine clathrate hydrate changes to blue after gamma irradiation and is bleachable with visible light. The electron spin resonance (ESR) spectrum at 120 K mainly consists of a triplet signal of the C-centered radical NH2C(CH3)2CH2• together with a single signal at g = 2.0008. The latter signal disappears after light exposure. These results indicate that both the blue color and the single ESR signal are derived from trapped electrons in the hydrate. They thermally decay around 140-160 K by the first-order reaction, and the activation energy is 27 kJ/mol. Since tert-butylamine molecules can capture protons due to the high proton affinity, electrons may remain in the hydrate without reacting with protons, making the hydrate blue after gamma irradiation. The long-lived trapped electrons in the tert-butylamine hydrate have an advantage to investigate those in icy materials because tert-butylamine hydrate is nonionic and has a tetra-coordinated host water network like crystalline ice without any substitution for water molecules.

Thermodynamic stability boundaries of the mixed hydrate composed of methane and fluorocyclopentane, chlorocyclopentane, or bromocyclopentane were investigated in a temperature range of (274.17 to 306.19) K and pressures up to 9.93 MPa under the four-phase (hydrate, aqueous, monohalogenated cyclopentane-rich liquid, and gas phases) equilibrium conditions. Also, the crystal structure of the methane + chlorocyclopentane hydrate was determined by means of powder X-ray diffractometry. The each boundary is laid at a pressure lower and a temperature higher than that of the simple methane hydrate. Especially, the methane + fluorocyclopentane hydrate system has the lowest equilibrium pressure among three mixed hydrate systems investigated in the present study. The powder X-ray diffraction patterns reveal that a guest species larger than chrolocyclopentane and smaller than bromocyclopentane is at the border between structure-II and structure-H hydrate formers.

Tomohiro Tanabe, Takeshi Sugahara, Kazuma Kitamura et al. High-Pressure Phase Equilibria of Tertiary-Butylamine Hydrates with and without Hydrogen, Journal of Chemical & Engineering Data, 60 (2), 222–227, February 12, © 2015 American Chemical Society. https://doi.org/10.1021/je5003016, Thermodynamic stability boundaries of the simple tertiary-butylamine (t-BA) hydrate and t-BA+hydrogen (H2) mixed hydrate were investigated at a pressure up to approximately 100 MPa. All experimental results from the phase equilibrium measurement, in situ Raman spectroscopy, and powder X-ray diffraction analysis arrive at the single conclusion that the t-BA hydrates, under pressurization with H2, are transformed from the structure VI simple t-BA hydrate into the structure II t-BA+H2 mixed hydrate. The phase transition point on the hydrate stability boundary in the mother aqueous solutions with the t-BA mole fractions (xt-BA) of 0.056 and 0.093 is located at (2.35 MPa, 267.39 K) and (25.3 MPa, 274.19 K), respectively. On the other hand, in the case of the pressurization by decreasing the sample volume instead of supplying H2, the simple t-BA hydrate retains the structure VI at pressures up to 112 MPa on the thermodynamic stability boundary.

When hydrogen (H2) is mixed with small amounts of methane (CH4), the conditions required for clathrate hydrate formation can be significantly reduced when compared to that of simple H2 hydrate. With growing demand for CH4 as a commercially viable source of energy, H2 + CH4 binary hydrates may be more appealing than extensively studied H2 + tetrahydrofuran (THF) hydrates from an energy density standpoint. Using Raman spectroscopic and powder X-ray diffraction measurements, we show that hydrate structure and storage capacities of H2 + CH4 mixed hydrates are largely dependent on the composition of the initial gas mixture, total system pressure, and formation period. In some cases, H2 + CH4 hydrate kinetically forms structure I first, even though the thermodynamically stable phase is structure II.

Thermodynamic stability boundaries of carbon dioxide + cyclopentane, carbon dioxide + cyclopentanone, and carbon dioxide + fluorocyclopentane mixed hydrates have been investigated in the range of 274.19–293.72 K and up to 4.88 MPa. The phase equilibrium curves of the structure-II mixed hydrates are located at a temperature remarkably higher than that of the structure-I simple carbon dioxide hydrate. The highest temperature point of each four-phase (hydrate, aqueous, cyclopentane derivative-rich, and gas phases) equilibrium curve was 292.60 K (for the first system), 284.78 K (for the second system), and 293.72 K (for the third system)

Large-cage occupancy of hydrogen (H 2 ) in the H 2 +tetrahydrofuran (THF) hydrates has been ever reported only in the ex situ spectroscopic measurements with the quenched hydrate sample. In the present study, to verify the proof-of-concept for the large-cage occupancy of H 2 competitive with THF, in situ Raman spectra of H 2 in the H 2 +THF mixed hydrates were detected at 74.3 MPa and 265 K without the quenching procedure. The Raman spectra reveal that H 2 molecules occupy a part of large cages of the H 2 +THF mixed hydrates at a thermodynamically unstable region of simple H 2 hydrate.

The enclathration of 2,3,3,3-tetrafluoropropene (HFO-1234yf) has been investigated. In the binary system of HFO-1234yf+H2O, simple HFO-1234yf hydrate is not formed even at 50 MPa and 274.15 K. The addition of methane (CH4) as a help molecule results in the structure-II CH4+HFO-1234yf mixed-gas hydrate formation. With difluoromethane (HFC-32), instead of CH4, no HFC-32+HFO-1234yf mixed-gas hydrate is formed. Isothermal phase equilibria for the CH4+HFO-1234yf+H2O ternary system were measured at 279.15 K. Based on the extrapolation of two three-phase {(hydrate, aqueous, and gas phases) and (aqueous, HFO-1234yf-rich liquid, and gas phases)} equilibrium curves, the quadruple point of hydrate, aqueous, HFO-1234yf-rich liquid, and gas phases was determined.

Thermodynamic stability boundary of structure-H hydrates with large guest species and methane (CH4) at extremely high pressures has been almost unclear. In the present study, the four-phase equilibrium relations in the structure-H CH4 + 1,1,2,2,3,3,4-heptafluorocyclopentane (1,1,2,2,3,3,4-HFCP) mixed hydrate system were investigated in a temperature range of (281.05 to 330.12) K and a pressure range up to 373 MPa. The difference between equilibrium pressures in the structure-H CH4 + 1,1,2,2,3,3,4-HFCP mixed hydrate system and the structure-I simple CH4 hydrate system gets larger with increase in temperature. The structure-H CH4 + 1,1,2,2,3,3,4-HFCP mixed hydrate survives even at 330 K and 373 MPa without any structural phase transition. The maximum temperature where the structure-H CH4 + 1,1,2,2,3,3,4-HFCP mixed hydrate is thermodynamically stable is likely to be beyond that of the structure-H simple CH4 hydrate.

We report an iatrogenic radial arteriovenous fistula (AVF) in a 74-year-old woman presenting with right radial bruit and pain 8 months after sheath removal for cardiac catheterization. She refused surgical ligation and underwent balloon-assisted direct percutaneous embolization of the draining vein with N-butyl cyanoacrylate (NBCA). Another draining vein that developed immediately after the procedure was conservatively treated with 1 month of continuous band compression. However, its diameter gradually increased and, as the patient desired complete remission, an additional procedure was conducted 2 months after initial treatment. A second balloon-assisted direct percutaneous embolization was performed using a 50 % glucose solution, which resulted in complete resolution. Although surgical repair is considered to be the standard treatment, in patients where surgery is not indicated, endovascular intervention-although complicated-may be an alternative treatment modality.

The three-phase (hydrate, aqueous, and HFC-134a-rich liquid phases) equilibrium relations of the 1,1,1,2-tetrafluoroethane (HFC-134a) + water binary system were measured in a pressure range up to 293 MPa. The HFC-134a hydrate has a structural phase transition point from structure-II to structure-I at (65 ± 1) MPa and (282.2 ± 0.1) K, where the slope of the three-phase equilibrium curve is drastically changed. The Raman spectra of the HFC-134a molecule in the structure-I HFC-134a hydrate phase indicate that HFC-134a molecule occupies only large cage of structure-I at a pressure up to 293 MPa.

Isothermal phase equilibrium relations of the CO2 + 1,1,1,2-tetrafluoroethane (HFC-134a) and CO2 + 1,1-difluoroethane (HFC-152a) mixed-gas hydrate systems were measured at 279.15 K. The isothermal phase equilibria of the CO2 + HFC-134a mixed-gas hydrate system exhibit the heterogeneous azeotropic-like behavior derived from the structural phase transition of the mixed-gas hydrate. The CO2 + HFC-152a mixed-gas hydrate system shows neither a structural phase transition nor azeotropic-like behavior.

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 patient was performed the fenestration of the anterior vaginal wall 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.

Guest-free hydroquinone (HQ) clathrate was synthesized by the gas-phase reaction between host HQ and guest CO 2 molecules, followed by removal of the CO 2 guests by controlled heating process. The H 2 storage capacity of the guest-free HQ clathrate is highly sensitive to the loading pressure; at 298 K, it was found to be 0.19 wt.% at 10 MPa and 0.38 wt.% at 35 MPa. In particular, the guest-free HQ clathrate also exhibits an extremely fast uptake and release of H 2 in a time scale of a few seconds.

A 36-year-old man with an implanted arteriovenous shunt for hemodialysis was referred for shunt malfunction. Venography of the right upper extremity showed occlusion of the subclavian vein, and a SMART stent was deployed. The fully expanded stent immediately migrated centrally into the left pulmonary artery. As initial efforts to pass a snare over the stent failed, we intentionally passed a microguidewire through stent interstices, snared the end of the microguidewire to create a loop, and pulled the stent/microguidewire/snare combination back into the right ventricle where it separated from the loop because of stent mesh destruction. As the stent remained in the right ventricle, we advanced a 0.035-in. guidewire into the stent lumen, passed an angioplasty balloon over the guidewire, inflated the balloon in the stent, and performed pull-back into the right distal external iliac artery. The stent was then surgically removed via a right inguinal incision without eliciting any complications. Although retrieval of the stent malpositioned in the pulmonary artery was difficult, we retrieved it safely by applying various adjunctive techniques.