Large bi-axial tensile strain effect in epitaxial BiFeO3 film grown on single crystal PrScO3.

A BiFeO3 film is grown epitaxially on a PrScO3 single crystal substrate which imparts ~ 1.45% of biaxial tensile strain to BiFeO3 resulting from lattice misfit. The biaxial tensile strain effect on BiFeO3 is investigated in terms of crystal structure, Poisson ratio, and ferroelectric domain structure. Lattice resolution scanning transmission electron microscopy, precession electron diffraction, and X-ray diffraction results clearly show that in-plane interplanar distance of BiFeO3 is the same as that of PrScO3 with no sign of misfit dislocations, indicating that the biaxial tensile strain caused by lattice mismatch between BiFeO3 and PrScO3 are stored as elastic energy within BiFeO3 film. Nano-beam electron diffraction patterns compared with structure factor calculation found that the BiFeO3 maintains rhombohedral symmetry, i.e., space group of R3c. The pattern analysis also revealed two crystallographically distinguishable domains. Their relations with ferroelectric domain structures in terms of size and spontaneous polarization orientations within the domains are further understood using four-dimensional scanning transmission electron microscopy technique.

Progression of Kidney Injury with the Combination of Vancomycin and Piperacillin-Tazobactam or Cefepime in Sepsis-Associated Acute Kidney Injury.

Introduction: The combination of vancomycin/piperacillin-tazobactam is associated with increases in serum creatinine compared to other antibiotic combinations in the treatment of infections for hospitalized patients. However, the available literature is limited to the study of incident acute kidney injury (AKI). The combination has not been evaluated in patients with AKI already present and the degree to which the trajectory of AKI is influenced by this combination is unknown. Methods: This was a single center, retrospective cohort study of adult patients with sepsis and AKI present on admission prescribed a combination of vancomycin with either piperacillin-tazobactam or cefepime within the first 3 days of admission. The primary outcome was maximum serum creatinine observed within days 2-7 of the hospital stay. Subsequent kidney outcomes were evaluated at one week and hospital discharge. Results: Of 480 patients with sepsis and AKI who met inclusion criteria, 288 (60%) received vancomycin/piperacillin-tazobactam, and 192 (40%) received vancomycin/cefepime. Patients were well-matched on clinical factors, including severity of illness, stage of AKI, exposure to other nephrotoxins, and durations of antimicrobial therapy. There were no differences in AKI trajectory during the first week as assessed by maximum serum creatinine (2.1 (1.4-3.5) mg/dl vs. 2.1 (1.4-3.0) mg/dl; p=0.459) and AKI progression (24.0% vs. 23.4%; p=0.895). No differences were observed with other kidney related outcomes, including the need for dialysis (14.6% vs. 13.0%; p=0.628) or major adverse kidney events at hospital discharge (48.3% vs. 47.9%; p=0.941). Conclusions: In patients with sepsis and AKI, the combination of vancomycin/piperacillin-tazobactam compared to vancomycin/cefepime was not associated with higher serum creatinine values or AKI progression in the week following ICU admission.

Association of Phosphate Containing Solutions with Incident Hypophosphatemia in Critically Ill Patients Requiring Continuous Renal Replacement Therapy.

BACKGROUND: Hypophosphatemia in critically ill patients is a common electrolyte disturbance associated with a myriad of adverse effects. Critically ill patients requiring continuous renal replacement therapy (CRRT) are at high risk of hypophosphatemia and often require phosphate supplementation during therapy. The aim of this study was to evaluate the association of phosphate versus non-phosphate containing CRRT solutions with incident hypophosphatemia in critically ill patients requiring CRRT. MATERIALS AND METHODS: This is a single-center, retrospective, cohort study at a tertiary academic medical center of 1,396 adult patients requiring CRRT during their intensive care unit stay comprising 7,529 (phosphate containing) and 4,821 (non-phosphate containing) cumulative days of CRRT. Multivariable logistic regression was used to model the primary outcome of hypophosphatemia during CRRT according to exposure to phosphate versus non-phosphate containing CRRT solutions. RESULTS: Incident hypophosphatemia during CRRT, serum phosphate <2.5 mg/dL or 0.81 mmol/L, was significantly higher in the non-phosphate versus phosphate containing solution group: 304/489 (62%) versus 175/853 (21%) (p < 0.001). Cumulative phosphate supplementation was also significantly higher in the non-phosphate versus phosphate containing solution group: 79 (IQR: 0-320) versus 0 (0-16) mmol (p < 0.001). Non-phosphate solutions were associated with an 8-fold increase in the incidence of hypophosphatemia (adjusted OR 8.05; 95% CI 5.77, 11.26; p < 0.001). DISCUSSION/CONCLUSIONS: The use of phosphate containing CRRT solutions was independently associated with reduced risk of incident hypophosphatemia and decreased phosphate supplementation during CRRT. Interventional studies to confirm these findings are needed.