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Purpose Cardiopulmonary Exercise Testing (CPET) is the clinical standard to select HF pts for cardiac replacement therapy. INTERMACS profile is used to risk stratify pts who undergo LVAD. We aimed to evaluate the association of CPET performance parameters with INTERMACS profile at implant as well as with clinical outcomes early post LVAD. Methods A retrospective analysis of LVAD pts implanted from 3/10 to 5/19 with CPET data available within 2y of surgery: peak oxygen consumption (pVO2) and minute ventilation − carbon dioxide production relationship (VE/VCO2). The primary endpoints were INTERMACS profile ≤2 at implant and a composite of post LVAD in-hospital mortality, right ventricular failure (RVF) and renal replacement therapy (RRT). Length of stay (LOS) in relation to CPET performance parameters was also evaluated. Receiver Operating Characteristics (ROC) curve assessed the ability of pVO2 and VE/VCO2 to predict the composite endpoint. Results We studied 81 pts, median age 58 [IQR 16.5] y, 86% M, 41% ischemic, 48% HMII, 40% HM3 and 12% on other pumps. Median time from CPET to LVAD implant was 233 [388]d. Median pVO2 was 11.9[IQR 4.4] ml/kg/min and VE/VCO2 38 [IQR 10.3]. 46(56.8%) pts were INTERMACS ≤2 at implant. 6 pts died, 7 had RRT and 23 developed RVF during index admission. PVO2 and VE/VCO2 were not significantly different between INTERMACS ≤2 vs >2 groups (p=0.8 and p=0.15, respectively). ROC curves showed that pVO2 Conclusion In a real-world setting, CPET parameters obtained within 2 y of LVAD do not reliably predict INTERMACS profile at implant. However, pVO2 and VE/VCO2 can be helpful to identify pts at risk for in-hospital mortality, major complications and prolonged LOS post LVAD.

The operational characteristics of a hot gas desulfurization process involving regenerable sorbent injection and its subsequent collection with a ceramic filtration device were studied utilizing a bench-scale transport reactor. Hydrogen sulfide removal from simulated hot gas was evaluated as a function of both zinc oxide-based sorbent physical and chemical characteristics and various process parameters. In addition, the sorbent capture efficiency and regenerability of the ceramic filtration device were evaluated, and regeneration of sulfided sorbents via injection into an oxidizing gas was studied. For both sorbent sulfidation and spent sorbent regeneration, gas-solid reaction occurred both in the duct and within layers of partially reacted sorbent captured by the ceramic filter. Very high sulfur removal efficiencies were obtained only in highly reducing hot gas compositions at or above about 700 C, using stoichiometric ratio (defined as ZnO/H{sub 2}S ratio) values of about 1.5, and sorbent particles of about 20 {micro}m or less in diameter. Under such conditions, the experimental data indicated that reaction of H{sub 2}S with zinc vapor formed by reduction of zinc oxide contributed appreciably to sulfur removal. Negligible zinc loss from the hot zone of the reactor was detected, apparently due to rapid formation of zinc sulfide product layersmore » on zinc oxide particles. The ceramic filtration devices captured 100% of all sorbent particles and were fully regenerable over periods of several tens of injection/backpulse cleaning cycles. Spent sorbent could be fully regenerated rapidly at 850 C without problems due to exotherm generation.« less

The sulfidation reaction kinetics of fine particles of zinc titanate and zinc oxide with H{sub 2}S were studied in order to test the potential of the sorbent injection hot-gas desulfurization process. Fine sorbent particles with diameter between 0.3 and 60 {mu}m were sulfided with H{sub 2}S and/or reduced with H{sub 2} in a laminar flow reactor over the temperature range of 500-900{degrees}C. Sulfidation/reduction conversion was compared for different particle sizes and sorbents with various porosities and atomic ratios of Zn and Ti. In reduction of ZnO with H{sub 2} and without H{sub 2}S, significant amount of Zn was formed and vaporized, while the presence of H{sub 2}S suppressed elemental Zn formation. This suggests that H{sub 2}S may suppress the surface reduction of ZnO and/or gaseous Zn may react with H{sub 2}S homogeneously and form fine particles of ZnS. Formation and vaporization of elemental Zn from zinc titanate sorbents was slower than from zinc oxide with and without H{sub 2}S.

The primary goal is to demonstrate the performance of a new ceramic filter in removing particulate matter from hot gas streams produced in advanced coal conversion processes. The specific objectives are threefold: (1) Development of full size ceramic filters suitable for hot gas filtration; (2) Demonstration of ceramic filters in long term (ca. 1000 hrs) field trials; and (3) Development of full-scale hot gas filter system designs and costs. To date, field tests of the ceramic filter for particulate removal have been conducted at seven sites on a variety of gas streams and under a variety of test conditions. In general, the following performance characteristics have been observed: 1. Filtration face velocity (equivalent to an ``air to cloth ratio``) for flue gas tests is comparable to that for pulse jet bags operating at the same pressure drop. In hot gas tests, flow-pressure drop characteristics have been observed to be comparable to those for other ceramic filters. 2. Complete regeneration by a simple backpulse technique is achieved; i.e., no increase in clean filter resistance over repetitive cycles is observed. 3. No plugging of the filter passageways by badly caking particulates is observed. 4. Essentially complete particulate removal, including submicron particulate matter,more » is achieved.« less

In a study of infrared spectra of chemisorbed gases, variations in the intensities of the absorption bands of the solid adsorbents were observed in the presence of different gases. This behavior was most pronounced for the most opaque samples. This phenomenon has been related to sample emission arising from sample heating by the spectrometer source, and differences in the thermal conductivities of the gases present. Infrared absorption bands of silica adsorbents were influenced by surface hydroxyl groups, as the bands for silica with deuterated hydroxyl groups differed from those of ordinary silica.

Infra-red spectra of Sr 3 (PO 4 ) 2 and Ba 3 (PO 4 ) 2 havingPO 4 3− ions at C 3 v sites were measured, and band assignments were made. the F -matrix corresponding to a generalized valence force field was calculated from observed frequencies. Calculated valence force constants are in general agreement with those found for a PO 4 3− ion with T d symmetry. A larger force constant for PO bond stretching along the C 3 axis than for the remaining three PO bonds, is interpreted as due to the particular geometry of the orthophosphate structures as determined by Zachariasen.

A set of valence force constants is calculated for the P 2 O 7 4− ion in β-Mg 2 P 2 O 7 and a group of M IV P 2 O 7 compounds typified by ZrP 2 O 7 . The results agree generally with the relationships between bond orders and stretching force constants suggested by Cruickshank and Robinson. Bond distances calculated from the stretching force constants are in excellent agreement with observed PO bond distances in the M IV P 2 O 7 compounds, but not in β-Mg 2 P 2 O 7 . The values of the bending force constants support Lazerev's contention that the bridging oxygen is not firmly fixed in a linear POP configuration.