3 research outputs found
On the relative abundances of Cavansite and Pentagonite
Cavansite is a visually stunning blue vanadosilicate mineral with limited
occurrences worldwide, whereas Pentagonite is a closely related dimorph with
similar physical and chemical properties, yet is extremely rare. The reasons
behind Pentagonite's exceptional rarity remain largely unknown. In this study,
we utilize density functional theory (DFT) to investigate the electronic
structures of Cavansite and Pentagonite at ground state and finite pressures.
We then employ the Boltzmann probability model to construct a comprehensive
phase diagram that reveals the abundance of each species across a wide range of
pressure and temperature conditions. Our analysis reveals the key factors that
contribute to the relative scarcity of Pentagonite, including differences in
structural arrangement and electronic configurations between the two minerals.
Specifically, because of the peculiar arrangements of SiO4 polyhedra, Cavansite
forms a compact structure (about 2.7% less in volume) resulting in lower
energy. We also show that at a temperature of about 600K only about 1%
Pentagonite can be formed. This probability is only slightly enhanced within a
pressure range of up to about 3GPa. We also find that vanadium induces a highly
localized state in both of these otherwise large band gap insulators resulting
in extremely weak magnetic phase that is unlikely to be observed at any
reasonable finite temperature. Finally, our dehydration studies reveal that
water molecules are loosely bound inside the microporous crystals of Cavansite
and Pentagonite, suggesting potential applications of these minerals in various
technological fields
International Nosocomial Infection Control Consortiu (INICC) report, data summary of 43 countries for 2007-2012. Device-associated module
We report the results of an International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2007-December 2012 in 503 intensive care units (ICUs) in Latin America, Asia, Africa, and Europe. During the 6-year study using the Centers for Disease Control and Prevention's (CDC) U.S. National Healthcare Safety Network (NHSN) definitions for device-associated health care–associated infection (DA-HAI), we collected prospective data from 605,310 patients hospitalized in the INICC's ICUs for an aggregate of 3,338,396 days. Although device utilization in the INICC's ICUs was similar to that reported from ICUs in the U.S. in the CDC's NHSN, rates of device-associated nosocomial infection were higher in the ICUs of the INICC hospitals: the pooled rate of central line–associated bloodstream infection in the INICC's ICUs, 4.9 per 1,000 central line days, is nearly 5-fold higher than the 0.9 per 1,000 central line days reported from comparable U.S. ICUs. The overall rate of ventilator-associated pneumonia was also higher (16.8 vs 1.1 per 1,000 ventilator days) as was the rate of catheter-associated urinary tract infection (5.5 vs 1.3 per 1,000 catheter days). Frequencies of resistance of Pseudomonas isolates to amikacin (42.8% vs 10%) and imipenem (42.4% vs 26.1%) and Klebsiella pneumoniae isolates to ceftazidime (71.2% vs 28.8%) and imipenem (19.6% vs 12.8%) were also higher in the INICC's ICUs compared with the ICUs of the CDC's NHSN