A comparison of struvite precipitation thermodynamics and kinetics modelling techniques.

Solution thermodynamics and kinetic modelling applied to struvite crystallisation-precipitation were reviewed from diverse references to determine proximity between predicted and cited experimental measurements. These simulations show the expected variability range of struvite saturation calculation when only limited solution compositional information is given, showing acceptable agreement between predicted and experimental struvite mass. This work also compares results from struvite crystallisation kinetic studies on liquid phase species depletion, crystallisation induction time, primary nucleation, secondary nucleation, crystal growth, and crystal aggregation. Large inconsistencies between reported kinetics were observed in many scenarios. Variations in species depletion models highlighted that they are only suitably applied to the specific system from which they were regressed. Spontaneous primary nucleation was predicted to occur in the range of SI = 0.237-0.8. Predicted primary nucleation rates vary over at least 10 orders of magnitude (depending on supersaturation) because of uncertainties in interfacial tension and maximum achievable nucleation rate. Secondary nucleation rates are more agreeable, varying over approximately two orders of magnitude. Growth rates varied over five orders of magnitude due to variations in experimental conditions. Aggregation rates are not thoroughly examined enough to make any inferences.

Comparison of Medication History Accuracy Between Nurses and Pharmacy Personnel.

PURPOSE:: To evaluate the differences in medication history errors made by pharmacy technicians, students, and pharmacists compared to nurses at a community hospital. METHODS:: One hundred medication histories completed by either pharmacy or nursing staff were repeated and evaluated for errors by a fourth-year pharmacy student. The histories were analyzed for differences in the rate of errors per medication. Errors were categorized by their clinical significance, which was determined by a panel of pharmacists, pharmacy students, and nurses. Errors were further categorized by their origin as either prescription (Rx) or over the counter (OTC). The primary outcome was the difference in the rate of clinically significant errors per medication. Secondary outcomes included the differences in the rate of clinically insignificant errors, Rx errors, and OTC errors. Differences in the types of errors for Rx and OTC medications were also analyzed. Additionally, the number of patients with no errors was compared between both groups. RESULTS:: The pharmacy group had a lower clinically significant error rate per medication (0.03 vs 0.09; relative risk [RR] = 0.66; 95% confidence interval [CI]: 0.020-0.093; P = .003). For secondary outcomes, the pharmacy group had a lower total error rate (0.21 vs 0.36, RR = 0.58; 95% CI: 0.041-0.255; P = .007), Rx error rate (0.09 vs 0.27, RR = 0.44; 95% CI: 0.071-0.292; P = .002), and OTC error rate (0.24 vs 0.46; RR = 0.52; 95% CI: 0.057-0.382; P = .009) per medication. The pharmacy group completed 20% more medication histories without Rx errors ( P = .045) and 25% more histories without OTC errors ( P = .041). CONCLUSION:: This study demonstrated that expanded use of pharmacy technicians and students improves the accuracy of medication histories in a community hospital.

Introduction of a Chemical-Free Metal PDMS Thermal Bonding for Fabrication of Flexible Electrode by Metal Transfer onto PDMS.

Polydimethylsiloxane (PDMS) is a flexible and biocompatible material widely used in the fabrication of microfluidic devices, and is often studied for the fabrication of flexible electrodes. The most popular method of fabricating a flexible electrode using PDMS is done by transferring a metal electrode onto said PDMS. However, the transfer process is difficult and the transferred metal layer is easily damaged due to inherently weak adhesion forces between the metal and PDMS, thus requiring a chemical treatment or sacrificial layer between the two. The fabrication process using a chemical treatment or sacrificial layer is complicated and expensive, which is the major limitation of using PDMS in the fabrication of flexible electrodes. This paper discusses the findings of a possible solution to create strong bonding between PDMS and various metals (copper, nickel and silver) using a chemical-free metal to PDMS thermal bonding technique. This method is the same as the PDMS curing process, but with a variation in the curing condition. The condition required to create strong bonding was studied by observing copper transferred by various PDMS curing conditions, including the standard condition. The condition creating the strong bonding was baking PDMS (5:1 = base polymer: curing agent) at 150 °C for 20 min. Experimentation showed that the optimum thickness of the transferred metal shows that the optimum thickness is approximately 500 nm, which allows for a higher resistance to stresses. The successful transfer of copper, nickel and silver layers onto PDMS with a stronger adhesion force opens up many new applications dealing with the fabrication of flexible electrodes, sensors, and flexible soft magnets.

Phaseguide-assisted blood separation microfluidic device for point-of-care applications.

We propose a blood separation microfluidic device suitable for point-of-care (POC) applications. By utilizing the high gas permeability of polydimethylsiloxane (PDMS) and phaseguide structures, a simple blood separation device is presented. The device consists of two main parts. A separation chamber with the phaseguide structures, where a sample inlet, a tape-sealed outlet, and a dead-end ring channel are connected, and pneumatic chambers, in which manually operating syringes are plugged. The separation chamber and pneumatic chambers are isolated by a thin PDMS wall. By manually pulling out the plunger of the syringe, a negative pressure is instantaneously generated inside the pneumatic chamber. Due to the gas diffusion from the separation chamber to the neighboring pneumatic chamber through the thin permeable PDMS wall, low pressure can be generated, and then the whole blood at the sample inlets starts to be drawn into the separation chamber and separated through the phaseguide structures. Reversely, after removing the tape at the outlet and manually pushing in the plunger of the syringe, a positive pressure will be created which will cause the air to diffuse back into the ring channel, and therefore allow the separated plasma to be recovered at the outlet on demand. In this paper, we focused on the study of the plasma separation and associated design parameters, such as the PDMS wall thickness, the air permeable overlap area between the separation and pneumatic chambers, and the geometry of the phaseguides. The device required only 2 µl of whole blood but yielding approximately 0.38 µl of separated plasma within 12 min. Without any of the requirements of sophisticated equipment or dilution techniques, we can not only separate the plasma from the whole blood for on-chip analysis but also can push out only the separated plasma to the outlet for off-chip analysis.