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Background: The purpose of this study was to find out the relationship between appropriateness of antibiotic prescription and clinical outcomes in patients with community-acquired acute pyelonephritis (CA-APN). Methods: A multicenter prospective cohort study was performed in 8 Korean hospitals from September 2017 to August 2018. All hospitalized patients aged ≥19 years diagnosed with CA-APN at admission were recruited. Pregnant women and patients with insufficient data were excluded. In addition, patients with prolonged hospitalization due to medical problems that were not associated with APN treatment were excluded. The appropriateness of empirical and definitive antibiotics was divided into “optimal,” “suboptimal,” and “inappropriate,” and optimal and suboptimal were regarded as appropriate antibiotic use. The standard for the classification of empirical antibiotics was defined reflecting the Korean national guideline for the antibiotic use in urinary tract infection 2018. The standards for the classification of definitive antibiotics were defined according to the result of in vitro susceptibility tests of causative organisms. Clinical outcomes including clinical failure (mortality or recurrence) rate, hospitalization days, and medical costs were compared between patients who were prescribed antibiotics appropriately and those who were prescribed them inappropriately. Results: In total, 397 and 318 patients were eligible for the analysis of the appropriateness of empirical and definitive antibiotics, respectively. Of these, 10 (2.5%) and 18 (5.7%) were inappropriately prescribed empirical and definitive antibiotics, respectively, and 28 (8.8%) were prescribed either empirical or definitive antibiotics inappropriately. Patients who were prescribed empirical antibiotics appropriately showed a lower mortality rate (0 vs 10%; P = .025), shorter hospitalization days (9 vs 12.5 days; P = .014), and lower medical costs (US$2,333 vs US$4,531; P = .007) compared to those who were prescribed empirical antibiotics “inappropriately.” In comparison, we detected no significant differences in clinical outcomes between patients who were prescribed definitive antibiotics appropriately and those who were prescribed definitive antibiotics inappropriately. Patients who were prescribed both empirical and definitive antibiotics appropriately showed a lower clinical failure rate (0.3 vs 7.1%; P = .021) and shorter hospitalization days (9 vs 10.5 days; P = .041) compared to those who were prescribed either empirical or definitive antibiotics inappropriately. Conclusions: Appropriate use of antibiotics leads patients with CA-APN to better clinical outcomes including fewer hospitalization days and lower medical costs.
Lithium based complex hydrides, including lithium aluminum hydrides and lithium borohydride (LiAlH4, Li3AlH6 and LiBH4), are among the most promising materials due to their high hydrogen contents. In the present work, we investigated the hydrogen storage properties of a new combined system of Li3AlH6-LiBH4. The samples were made with small amounts of catalyst under low energy milling conditions. Thermogravimetric analysis (TGA) of a Ti-doped Li3AlH6/2LiBH4 indicated that the degree of hydrogen release reached 7.3 wt. % by the time the sample reached 450iÆc under a heating rate of 2iÆC/min. This increased to 8.8 wt. % when the sample was held at 450iÆCfor additional 8 hours minutes under this condition. The dehydrogenation product was a mixture of LiH and AlB2. This product could be rehydrogenated up to 3.8 wt. % under 24.1 MPa hydrogen pressure and 450iÆC.
Metal hydrides and amides are potential candidate materials for hydrogen storage. Lithium- and magnesium-based material systems are among the most promising materials owing to their high hydrogen contents. In the present work, we investigated hydrogenation/dehydrogenation reactions of a binary nitride, LiMgN. LiMgN can be formed by a reaction of MgH2 with LiNH2 in 1:1 ratio. The reaction also releases approximately ∼ 8.1 wt% H2 (theoretical value is 8.2 wt%) between 160 and 220 °C. The reaction product LiMgN can be rehydrogenated by reacting with H2 under 2000 psi of hydrogen pressure and 160 °C with small amount of TiCl3 doping. TGA results showed that about 8.0 wt% of hydrogen was stored in TiCl3-doped LiMgN during the hydrogenation process. The reversible hydrogenation and dehydrogenation mechanisms involving LiMgN and H2 are discussed.
Combustion synthesis of titanium borides from Ti and B binary powder mixtures having molar ratios B/Ti of 1.9 to 2.4 resulted in the formation of TiB2 as the primary phase and TiB as the secondary phase. The amount of TiB decreased when the particle size of the Ti in the powder mixtures became small and when the B content was increased. The results are discussed in terms of the homogeneity of reactant powder mixtures and the degree of boron saturation of the Ti-B melt. The burning rate increased from 11 to 15 mm/s as the titanium particle size decreased from −100 to −325 mesh with the same boron particle size of –325 mesh.
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