Synthesis, Structure, and Heat Capacity of Some Basic Hydroxohalide Glasses of Zirconium and Hafnium.

This work highlights the synthesis and properties of novel basic hydroxohalide glasses of zirconium and hafnium. The hydroxohalide glasses are M(OH)4-αXα·(n)H2O where M represents either zirconium or hafnium, and X represents either chloride or bromide. The chemical structure is investigated using X-ray diffraction, total scattering, and the pair distribution function method to identify the local structure and any short-range connectivity. The thermodynamic properties of the glasses are probed using low-temperature heat capacity, where a gap in the phonon density of states is discussed and related to boson peaks in the heat capacity of the glasses. These results represent the first published synthesis and thermodynamic properties of zirconium and hafnium basic hydroxohalide glasses. Synthesis methods, structural determination, and analysis of the heat capacity data allow for a comprehensive look at the makeup and unique properties of these novel glassy materials. Values of the standard thermodynamic functions Cp,m°, Δ0TSm°, Δ0THm°, and Φm° are also reported.

Analysis of skew of visible laser reflections in a living sheep heart.

Limited methods exist to confirm the position of cardiovascular devices in the heart. In our earlier work, an optical fiber was enclosed in a central catheter and guided to known positions in the superior vena cava and right atrium in the heart of a living sheep. The tissues were illuminated with two wavelengths of visible light and the reflections were analyzed using frequency domain techniques. In this follow-up work, the data were reanalyzed using statistical estimates of skew and kurtosis as a function of anatomic position. Skew values from a 520 nm laser were able to determine catheter tip position near the cavoatrial junction as validated against known positions previously determined with electrocardiogram and contrast-enhanced video fluoroscopy. This method successfully confirmed the location of the catheter tip at the cavoatrial junction in 84% of 840 trials. Further research with refined apparatus and algorithms on additional animal subjects is strongly suggested.

Noninvasive Urine Oxygen Monitoring and the Risk of Acute Kidney Injury in Cardiac Surgery.

BACKGROUND: Acute kidney injury (AKI) is a common complication of cardiac surgery. An intraoperative monitor of kidney perfusion is needed to identify patients at risk for AKI. The authors created a noninvasive urinary oximeter that provides continuous measurements of urinary oxygen partial pressure and instantaneous urine flow. They hypothesized that intraoperative urinary oxygen partial pressure measurements are feasible with this prototype device and that low urinary oxygen partial pressure during cardiac surgery is associated with the subsequent development of AKI. METHODS: This was a prospective observational pilot study. Continuous urinary oxygen partial pressure and instantaneous urine flow were measured in 91 patients undergoing cardiac surgery using a novel device placed between the urinary catheter and collecting bag. Data were collected throughout the surgery and for 24 h postoperatively. Clinicians were blinded to the intraoperative urinary oxygen partial pressure and instantaneous flow data. Patients were then followed postoperatively, and the incidence of AKI was compared to urinary oxygen partial pressure measurements. RESULTS: Intraoperative urinary oxygen partial pressure measurements were feasible in 86/91 (95%) of patients. When urinary oxygen partial pressure data were filtered for valid urine flows greater than 0.5 ml · kg-1 · h-1, then 70/86 (81%) and 77/86 (90%) of patients in the cardiopulmonary bypass (CPB) and post-CPB periods, respectively, were included in the analysis. Mean urinary oxygen partial pressure in the post-CPB period was significantly lower in patients who subsequently developed AKI than in those who did not (mean difference, 6 mmHg; 95% CI, 0 to 11; P = 0.038). In a multivariable analysis, mean urinary oxygen partial pressure during the post-CPB period remained an independent risk factor for AKI (relative risk, 0.82; 95% CI, 0.71 to 0.95; P = 0.009 for every 10-mmHg increase in mean urinary oxygen partial pressure). CONCLUSIONS: Low urinary oxygen partial pressures after CPB may be associated with the subsequent development of AKI after cardiac surgery.

Predictors of compliance with COVID-19 related non-pharmaceutical interventions among university students in the United States.

The world is currently dealing with a devastating pandemic. Although growing COVID-19 case numbers, deaths, and hospitalizations are concerning, this spread is particularly alarming in the United States where polarizing opinions, changing policies, and misinformation abound. In particular, American college campuses have been a venue of rampant transmission, with concerning spillover into surrounding, more vulnerable, communities. We surveyed over 600 college students from across the United States and modeled predictors of compliance with non-pharmaceutical interventions. We identified concern with severity, constitutionalism, news exposure, and religiosity as significant positive correlates with compliance, and general trust in science as a significant negative correlate. To determine how applicable nationwide modeling might be to individual local campuses we also administered this same survey to nearly 600 students at two large universities in Utah County. In this population, concern with severity was the only significant positive correlate with compliance; Additionally, feelings of inconvenience were negatively correlated. The effects of feelings of inconvenience, and news exposure were significantly different between populations. These results suggest that we should focus our efforts on increasing knowledge about the pandemic's effects on our society and informing about constitutionality amongst college students. However, we also show that nationwide surveys and modeling are informative, but if campuses are to efficiently curb the spread of COVID-19 this coming semester, they would be best served to utilize data collected from their student populations as these might significantly differ from general consensus data.

Joint time-frequency analysis of visible laser reflections in a sheep heart.

Limited methods exist to confirm the position of cardiovascular devices in the superior vena cava or right atrium of the heart. The aim of this study was to design, test and validate the feasibility of whether an optical fiber-based instrument could accurately distinguish when a cardiovascular catheter was located in the superior vena cava vs in the right atrium. An optical fiber was placed in a cardiovascular catheter which was inserted into a living sheep and guided to the vicinity of the heart where diode laser-based reflection intensity data were simultaneously gathered from two visible wavelengths of light reflected from the venous and atrial tissue surfaces near the cavoatrial junction. The time series data were postoperatively analyzed using methods of joint time-frequency analysis and validated against catheter positions determined with fluoroscopy and ECG. The system was successful in distinguishing the location of the superior vena cava from the right atrium.

Dual-wavelength reflectance spectroscopy of the superior vena cava: A method for placing central venous catheters at the cavoatrial junction.

There are a limited number of methods to guide and confirm the placement of a peripherally inserted central catheter (PICC) at the cavoatrial junction. The aim of this study was to design, test and validate a dual-wavelength, diode laser-based, single optical fiber instrument that would accurately confirm PICC tip location at the cavoatrial junction of an animal heart, in vivo. This was accomplished by inserting the optical fiber into a PICC and ratiometrically comparing simultaneous visible and near-infrared reflection intensities of venous and atrial tissues found near the cavoatrial junction. The system was successful in placing the PICC line tip within 5 mm of the cavoatrial junction.