Management of hypophosphatemia in nocturnal hemodialysis with phosphate-containing enema: a technical study

Hypophosphatemia is observed in patients undergoing nocturnal hemodialysis. Phosphate is commonly added to the dialysate acid bath, but systematic evaluation of the safety and reliability of this strategy is lacking. The objectives of this study were 4‐fold. First, we determined whether predictable final dialysate phosphate concentrations could be achieved by adding varying amounts of Fleet^® enema. Second, we assessed the stability of calcium (Ca) and phosphate dialysate levels under simulated nocturnal hemodialysis conditions. Third, we assessed for Ca‐phosphate precipitate. Finally, we evaluated whether dialysate containing Fleet^® enema met the current sterility standards. We added serial aliquots of enema to 4.5 L of dialysate acid concentrate and proportioned the solution on Gambro and Althin/Baxter dialysis machines for up to 8 hours. We measured dialysate phosphate, Ca, pH, and bicarbonate concentrations at baseline, and after simulated dialysis at 4 and 8 hours. We evaluated for precipitation visually and by assessing optical density at 620 nm. We used inoculation of agar to detect bacteria and Pyrotell reaction for endotoxin. For every 30 mL of Fleet^® (1.38 mmol/mL of phosphate) enema added, the dialysate phosphate concentration increased by 0.2 mmol/L. There were no significant changes in dialysate phosphate, Ca, pH, and bicarbonate concentrations over 8 hours. No precipitate was observed in the dialysate by optical density measures at 620 nm for additions of up to 90 mL of enema. Bacterial and endotoxin testing met sterility standards. The addition of Fleet^® enema to dialysate increases phosphate concentration in a predictable manner, and no safety problems were observed in our in vitro studies.     

“Mapping” Smart Cities

ABSTRACT

Smart cities are designed to use data to optimize resources, maintain sustainability, and improve people’s quality of life. While many urban technologies are employed to make cities “smart,” one constellation of technologies has been less examined in the academic literature—digital maps and the spatial data infrastructure. This paper is an attempt to systematically review the functions and evolution of digital maps and the spatial data infrastructure, with examples from Asia and beyond, in supporting and making smart cities possible. Based on the conceptual framework and empirical case studies, four major research directions of smart mapping are identified to better support smart city initiatives.     

Realization of high thermoelectric performance in p-type unfilled ternary skutterudites FeSb2+xTe1−x via band structure modification and significant point defect scattering

FeSb₂Te, a ternary derivative of binary CoSb₃, displays anomalous electrical and thermal transport properties because of considerable modifications in the band structure induced by Fe and significant mixed valence state (namely Fe²⁺ and Fe³⁺) scattering of phonons. The substitution of Te for Sb generates more holes without notably affecting the band structure, while markedly improving the electrical conductivity and retaining a high Seebeck coefficient due to the enhanced density of states, thereby leading to dramatically increased power factors. Furthermore, the heat carrying phonons are strongly scattered with increasing x value because of the formation of solid solutions between two end members: □FeSb₂Te and □FeSb₃ (where □ can be viewed as a vacancy). Consequently, high thermoelectric figures of merit were achieved in the FeSb_2+xTe_1?x compounds, with the largest ZT value reaching ～0.65 for the sample with x = 0.2. This is the highest value among all p-type unfilled skutterudites and is comparable with some filled compositions. Prospects for further improving the performance of p-type FeSb₂Te-based skutterudites are discussed.     

The interactive use of a video database in teacher education: Creating a knowledge base for teaching through a learning community

This study explores how pre-service student teachers acquired knowledge of good teaching practices through the interactive use of a video database and an online discussion forum, where the student teachers shared their teaching videos and received comments or suggestions from members of a learning community. A small group of student teachers was involved in this collaborative learning community during their teaching practicum in their third and fourth years of study. Content analysis of the sharing in the discussion forum and individual student teacher reflections provides insight into the use of a collaborative learning community to create a knowledge base for teaching. Suggestions regarding how this new technology can support teacher education are discussed.     

Synthesis and characterization of framework-substituted Cs8Na16Cu5Ge131

We report the synthesis and temperature-dependent transport properties of a new type II germanium clathrate, Cs₈Na₁₆Cu₅Ge₁₃₁ (space group ; a = 15.42000(9) Å). In comparison to the parent compound Cs₈Na₁₆Ge₁₃₆, Cu substitution for Ge on the clathrate framework was found to increase in magnitude the electrical resistivity and Seebeck coefficient, while reducing the thermal conductivity. The results are consistent with partial charge compensation due to Cu substitution for Ge. In addition to presenting possibilities for new compositions, framework substitution in type II clathrates may offer a route to control the transport properties of these materials, and could offer potential candidates for thermoelectric applications.     

Application of Molecular Orbital Calculations to Fracture Mechanics: Effect of Applied Strain on Charge Distribution in Silica

To further our understanding of the mechanism of environmentally enhanced crack growth, molecular oribital calculations (MO) using the ab initio self-consistent-field (SCF) technique have been employed to investigate the effect of applied strain on the atomic charge distribution and the bond overlap population of the Si–O bond at the crack tip of silica. Pyrosilicic acid (H₆Si₂O₇) with eclipsed conformation has been employed as the model molecule. Strain effects up to 20% were simulated in terms of bond stretching and angle distortion. The results indicate that, regardless of how the external strain is applied on the model molecule, the gross electron population on the bridged oxygen increases as strain increases and that on the silicon decreases.