Impact of Australian natural gas and coal bed methane composition on PEM fuel cell performance

Several PEM fuel cell systems are currently being marketed or developed as natural gas fuelled stationary power generation or cogeneration systems. Whilst each of these may perform adequately when fuelled with methane, the composition of natural gas varies widely around the world, according to the source and even the season. This study investigated the variation in composition of fuel gas supplied in pipeline systems around Australia and how its chemical composition may affect the performance of PEM fuel cell systems than employ steam reforming, shift and selective preferential oxidation to convert the fuel gas to hydrogen. The study showed that the performance of the fuel cell system is affected by the chemical composition and that ammonia formed from gases with high nitrogen concentrations could limit the applicability of PEM fuel cells, and should be taken into account when manufacturers specify the allowable fuel gas compositions for their systems.     

How do clinicians reconcile conditions and medications? The cognitive context of medication reconciliation

Medication omissions and dosing failures are frequent during transitions in patient care. Medication reconciliation (MR) requires bridging discrepancies in a patient’s medical history as a setting for care changes. MR has been identified as vulnerable to failure, and a clinician’s cognition during MR remains poorly described in the literature. We sought to explore cognition in MR tasks. Specifically, we sought to explore how clinicians make sense of conditions and medications. We observed 24 anesthesia providers performing a card-sorting task to sort conditions and medications for a fictional patient. We analyzed the spatial properties of the data using statistical methods. Most of the participants (58%) arranged the medications along a straight line (p < 0.001). They sorted medications by organ systems (Friedman’s χ ²(54) = 325.7, p < 0.001). These arrangements described the clinical correspondence between each two medications (Wilcoxon W = 192.0, p < 0.001). A cluster analysis showed that the subjects matched conditions and medications related to the same organ system together (Wilcoxon W = 1917.0, p < 0.001). We conclude that the clinicians commonly arranged the information into two groups (conditions and medications) and assigned an internal order within these groups, according to organ systems. They also matched between conditions and medications according to similar criteria. These findings were also supported by verbal protocol analysis. The findings strengthen the argument that organ-based information is pivotal to a clinician’s cognition during MR. Understanding the strategies and heuristics, clinicians employ through the MR process may help to develop practices to promote patient safety.     

Incorporating Both Physical and Kinetic Limitations in Quantifying Dissolved Oxygen Flux to Aquatic Sediments

Traditionally, dissolved oxygen (DO) fluxes have been calculated using the thin-film theory with DO microstructure data in systems characterized by fine sediments and low velocities. However, recent experimental evidence of fluctuating DO concentrations near the sediment-water interface suggests that turbulence and coherent motions control the mass transfer, and the surface renewal theory gives a more mechanistic model for quantifying fluxes. Both models involve quantifying the mass transfer coefficient (k) and the relevant concentration difference (ΔC). This study compared several empirical models for quantifying k based on both thin-film and surface renewal theories, as well as presents a new method for quantifying ΔC (dynamic approach) that is consistent with the observed DO concentration fluctuations near the interface. Data were used from a series of flume experiments that includes both physical and kinetic uptake limitations of the flux. Results indicated that methods for quantifying k and ΔC using the surface renewal theory better estimated the DO flux across a range of fluid-flow conditions.     

Reliability of thin ZrO2 gate dielectric layers

In this work we examine the positive bias temperature instability (PBTI) and stress induced leakage current (SILC) reliability of nFET devices with thin (2.5 nm) ZrO₂ gate dielectric layers. nFET devices show anomalous PBTI behavior in the form of a negative threshold voltage (V_t) shift during positive bias stress with little temperature dependence and it is not ‘frozen out’ at lower temperatures, indicating a single non-diffusion based mechanism. Correlations between the PBTI and the stress induced leakage current (SILC) suggest that the PBTI effect originates from trapping into empty defects which are initially detected as SILC and located just below the silicon conduction band. These defects also appear to be linked to the time dependent dielectric breakdown behavior.     

Characteristics for Leveraging Value Management Processes on Capital Facility Projects

A more competitive business environment requires that a variety of value management process (VMP) options be continuously introduced into the construction industry. Project stakeholders and managers are highly concerned about value maximization through implementation of one or more beneficial VMP options. The objective of this study is to identify the most leveraging project characteristic factors (PCFs) in need of VMP implementation. Furthermore, the levels of importance of each PCF in association with the optional VMPs are quantified to effectively assess the applicability of VMP implementation using the fuzzy-based analytic hierarchy process method. Four real-case validation tests provide robust research findings. The proposed project assessment tool is useful in evaluating individual projects in terms of whether the subject project is leveraged or has much to be improved by implementing the optional VMPs. The results of this study can facilitate a rigorous evaluation of a project and eventually help the decision-making process in selecting the most beneficial VMP options to maximize the optimum project value.     

On segmenting the three-dimensional scan data of a human body

Software for categorizing a cloud of more than 300,000 three-dimensional (3-D) surface data points, captured from a human subject, is presented. The software is part of an incremental approach that progressively refines the identification of human anthropometric landmarks. The first phase of identification is to orient and segment the human body data points. A step-by-step method for these tasks is presented. One of the algorithms, a discrete point cusp detector, plays a fundamental role in separating the data cloud. The theory and operation of the algorithm is explained. The discrete cusp detector can be used to separate any two cylindrical objects, in (3-D) data, whose boundaries touch. The software has been tested on over a hundred different body scan data sets and shown to be robust.     

NMDA-receptor antagonists: new pharmacological agents to control the subjective and motivational effects of narcotics]

The effects of N-methyl-D-aspartate. (NMDA) receptor antagonists on the development of long-term adaptation to abused drugs (tolerance, sensitization, dependence) were studied, NMDA receptor antagonists were shown to suppress subjective (including an aversion-motivation component) signs of the opiate withdrawal syndrome and to diminish the secondary reinforcing effects of morphine, cocaine, and electrical brain stimulation rewards of the brain regions. The results obtained indicate the potential efficiency of this new class of pharmacological agents in the context of treatment and prevention of recurrent drug abuse.     

Effects of fibroblast growth factor-2 on longitudinal bone growth

In vivo, fibroblast growth factor-2 (FGF-2) inhibits longitudinal bone growth. Similarly, activating FGF receptor 3 mutations impair growth in achondroplasia and thanatophoric dysplasia. To investigate the underlying mechanisms, we chose a fetal rat metatarsal organ culture system that would maintain growth plate histological architecture. Addition of FGF-2 to the serum-free medium inhibited longitudinal growth. We next assessed each major component of longitudinal growth: proliferation, cellular hypertrophy, and cartilage matrix synthesis. Surprisingly, FGF-2 stimulated proliferation, as assessed by [3H]thymidine incorporation. However, autoradiographic studies demonstrated that this increased proliferation occurred only in the perichondrium, whereas decreased labeling was seen in the proliferative and epiphyseal chondrocytes. FGF-2 also caused a marked decrease in the number of hypertrophic chondrocytes. To assess cartilage matrix synthesis, we measured 35SO4 incorporation into newly synthesized glycosaminoglycans. Low concentrations (10 ng/ml) of FGF-2 stimulated cartilage matrix production, but high concentrations (1000 ng/ml) inhibited matrix production. We conclude that FGF-2 inhibits longitudinal bone growth by three mechanisms: decreased growth plate chondrocyte proliferation, decreased cellular hypertrophy, and, at high concentrations, decreased cartilage matrix production. These effects may explain the impaired growth seen in patients with achondroplasia and related skeletal dysplasias.     

The effect of changing excitation frequency on parallel conductance in different sized hearts

OBJECTIVE: An important component of the ventricular volume measured using the conductance catheter technique is due to parallel conductance (Vc), which results from the extension of the electric field beyond the ventricular blood pool. Parallel conductance volume is normally estimated using the saline dilution method (Vc(saline dilution)), in which the conductivity of blood in the ventricle is transiently increased by injection of hypertonic saline. A simpler alternative has been reported by Gawne et al. [12]. Vc(dual frequency) is estimated from the difference in total conductance measured at two exciting frequencies and the method is based on the assumption that parallel conductance is mainly capacitive and hence is negligible at low frequency. The objective of this study was to determine whether the dual frequency technique could be used to substitute the saline dilution method to estimate Vc in different sized hearts. METHODS: The accuracy and linearity of a custom-built conductance catheter (CC) system was initially assessed in vitro. Subsequently, a CC and micromanometer were inserted into the left ventricle of seven 5 kg pigs (group 1) and six 50 kg pigs (group 2). Cardiac output was determined using thermodilution (group 1) and an ultrasonic flow probe (group 2) from which the slope coefficient (alpha) was determined. Steady state measurements and Vc estimated using saline dilution were performed at frequencies in the range of 5-40 kHz. All measurements were made at end-expiration. Finally, Vc was estimated from the change in end-systolic conductance between 5 kHz and 40 kHz using the dual frequency technique of Gawne et al. [12]. RESULTS: There was no change in measured volume of a simple insulated cylindrical model when the stimulating frequency was varied from 5-40 kHz. Vc(saline dilution) varied significantly with frequency in group 1 (8.63 +/- 2.74 ml at 5 kHz; 11.51 +/- 2.65 ml at 40 kHz) (p = 0.01). Similar results were obtained in group 2 (69.43 +/- 27.76 ml at 5 kHz; 101.24 +/- 15.21 ml at 40 kHz) (p < 0.001). However, the data indicate that the resistive component of the parallel conductance is substantial (Vc at 0 Hz estimated as 8.01 ml in group 1 and 62.3 ml in group 2). There was an increase in alpha with frequency in both groups but this did not reach significance. The correspondence between Vc(dual frequency) and Vc(saline dilution) methods was poor (group 1 R2 = 0.69; group 2 R2 = 0.22). CONCLUSION: At a lower excitation frequency of 5 kHz a smaller percentage of the electric current extends beyond the blood pool so parallel conductance is reduced. While parallel conductance is frequency dependent, it has a substantial resistive component. The dual frequency method is based on the assumption that parallel conductance is negligible at low frequencies and this is clearly not the case. The results of this study confirm that the dual frequency technique cannot be used to substitute the saline dilution technique.