Development of a point-of-care breath ammonia device and its application to non-invasive monitoring of haemodialysis patients

Initial investigation into diagnostic breath ammonia monitoring, and the current status of technology, indicated that breath analysis would have great potential as a non-invasive means of diagnosis. The ideal breath ammonia monitoring device would be one that is sensitive to the specific gas and capable of detecting it at the physiologically relevant concentrations in the ppb range with (1) good precision and accuracy, (2) insensitivity to interferences, (3) is ideally portable for point-of-care use, (4) provides ease-of-use to the user, (5) displays real-time measurements, and (6) is of low cost. To begin assessment, the normal range of human breath ammonia was defined via photoacoustic laser spectroscopy (PALS) which identified baseline concentrations to be from 29 to 688 ppb. Following this, a system was developed to simulate breath interferents such as humidity and temperature over a human range encompassing normal and abnormal breath ammonia concentrations (18 to 2,993 ppb). This instrumentation assisted in evaluating the performance of an ammonia sensitive electrode based on print-fabrication technology and polyaniline nanoparticles. The electrodes displayed an intra-variability from 0.05 to 1.67%, and generated a 0.99 correlation across a range of 40 to 2,175 ppbv ammonia (LOD=6.3 ppbv) fulfilling the analytical and biomedical requirements necessary for sensing ammonia in exhaled breath. Having optimised the ammonia sensor, a breath sampling system (AmBeR) was engineered and optimised which was capable of performing measurement of breath ammonia at the point-of-care. Observations of breath from a healthy population demonstrated a 0.97 correlation between AmBeR and PALS. Clinical evaluation followed in a haemodialysis patient cohort. While the clinical results did not show strong population correlations with measures of blood nitrogen (r=0.64 BUN, r=0.62 creatinine, p<0.01), it did show strong significant intra-individual correlations (range 0.86 - 0.96 with BUN, 0.78 - 0.97 with creatinine) which may indicate potential for clinical application

A system for the continuous generation of simulated human breath supplemented with trace gases

A system was developed to simulate the relative humidity (RH) and temperature characteristics of human breath at a constant human volume flow rate. The system was also designed to allow supplementation of the artificial breath with known concentrations of a trace gas; in this case, ammonia. The system was assembled from several components including an air pump, respiratory humidifier, mass flow controllers and additional valves and sensors to monitor and verify the system variables. Flow rates were measured as maximum voluntary ventilation (MVV) and could be set to standards within human levels. The desired temperature (i.e. 32 to 37°C) and relative humidity (i.e. 91 to 96%) ranges could be achieved over defined operational periods. Good agreement for the concentration of ammonia in the simulated breath matrix was obtained between the theoretically calculated concentration and with photoacoustic spectroscopy in the clinically relevant range of 18 to 2993 ppb (r 2 = 0.9978). The system can be used for the calibration of sensors being developed for breath monitoring applications. © 2012 The Royal Society of Chemistry

Direct measurement of ammonia in simulated human breath using an inkjet-printed polyaniline nanoparticle sensor

A sensor fabricated from the inkjet-printed deposition of polyaniline nanoparticles onto a screen-printed silver interdigitated electrode was developed for the detection of ammonia in simulated human breath samples. Impedance analysis showed that exposure to ammonia gas could be measured at 962Hz at which changes in resistance dominate due to the deprotonation of the polymer film. Sensors required minimal calibration and demonstrated excellent intra-electrode baseline drift (≤1.67%). Gases typically present in breath did not interfere with the sensor. Temperature and humidity were shown to have characteristic impedimetric and temporal effects on the sensor that could be distinguished from the response to ammonia. While impedance responses to ammonia could be detected from a single simulated breath, quantification was improved after the cumulative measurement of multiple breaths. The measurement of ammonia after 16 simulated breaths was linear in the range of 40-2175ppbv (27-1514μgm-3) (r2=0.9963) with a theoretical limit of detection of 6.2ppbv (4.1μgm-3) (SN-1=3). © 2013 Elsevier B.V

Point of care monitoring of hemodialysis patients with a breath ammonia measurement device based on printed polyaniline nanoparticle sensors

A device for measuring human breath ammonia was developed based on a single use, disposable, inkjet printed ammonia sensor fabricated using polyaniline nanoparticles. The device was optimized for sampling ammonia in human breath samples by addressing issues such as variations in breath sample volume, flow rate, sources of oral ammonia, temperature and humidity. The resulting system was capable of measuring ammonia in breath from 40 to 2993 ppbv (r2= 0.99, n = 3) as correlated with photoacoustic laser spectroscopy and correlation in normal human breath samples yielded a slope of 0.93 and a Pearson correlation coefficient of 0.9705 (p < 0.05, n = 11). Measurement of ammonia in the breath of patients with end-stage kidney disease demonstrated its significant reduction following dialysis, while also correlating well with blood urea nitrogen (BUN) (r = 0.61, p < 0.01, n = 96). Excellent intraindividual correlations were demonstrated between breath ammonia and BUN (0.86 to 0.96), which demonstrates the possibility of using low cost point of care breath ammonia systems as a noninvasive means of monitoring kidney dysfunction and treatment. © 2013 American Chemical Society

It’s Never Been Just for Boys: Female Fans of NCAA Division I and Professional Sports

College and professional sports depend on fans. Female fans constitute a lucrative but often neglected demographic in the sport industry. While marketers and advertisers recognize the power of the female customer, many sport organizations marginalize female fans by virtue of omission. Given the multi-dimensional nature of the female sport fan and the growth potential of the fan base, the sport industry must pay attention. This makes good sense not only ethically and socially, but economically as well since this demographic is steadily growing while the male fan base remains stable. The current study examined consumer practices and attitudes of female fans at professional and Division I college revenue sporting events during the 2013-14 season. Over 900 female fans of NCAA Division I revenue sports (football, men’s basketball, women’s basketball), professional basketball and professional hockey were interviewed regarding both consumer choices and their perceived value as fans. Results indicate specific expressed needs and preferences of female fans. Of great interest is the preponderance of female college-sport fans who declared themselves as valued “long-time fans” compared to the relatively short-time nature of the professional sport fans. Implications for the sport industry include the importance of including female demographics in brand strategy and loyalty

Breath ammonia analysis: Clinical application and measurement

This review covers in detail the complexity of human breath, how the body metabolizes ammonia, clinical conditions which are directly related to the regulation of ammonia concentration, and analysis of current techniques that are capable of detecting breath ammonia. Focusing on these areas provides the information needed to develop a breath ammonia sensor for monitoring dysfunction of the human body. Human breath has been broken down into its key components which are necessary for proper understanding of what to look for when attempting to isolate volatile organic compounds. A pathway has been shown which explains the origin of ammonia in the body and how it is processed within a healthy system. Following this, the hazards of several dysfunctions related to the broken ammonia pathway have been discussed. It is essential that technicians have knowledge of these inner workings of the human body along with current technology. Thus, the advantages and disadvantages of techniques from chemical ionization, gas chromatography, laser spectroscopy, and chemical sensing have been discussed. © Taylor and Francis Group, LLC

Coronal Heating as Determined by the Solar Flare Frequency Distribution Obtained by Aggregating Case Studies

Flare frequency distributions represent a key approach to addressing one of the largest problems in solar and stellar physics: determining the mechanism that counter-intuitively heats coronae to temperatures that are orders of magnitude hotter than the corresponding photospheres. It is widely accepted that the magnetic field is responsible for the heating, but there are two competing mechanisms that could explain it: nanoflares or Alfv\'en waves. To date, neither can be directly observed. Nanoflares are, by definition, extremely small, but their aggregate energy release could represent a substantial heating mechanism, presuming they are sufficiently abundant. One way to test this presumption is via the flare frequency distribution, which describes how often flares of various energies occur. If the slope of the power law fitting the flare frequency distribution is above a critical threshold, $\alpha=2$ as established in prior literature, then there should be a sufficient abundance of nanoflares to explain coronal heating. We performed $>$600 case studies of solar flares, made possible by an unprecedented number of data analysts via three semesters of an undergraduate physics laboratory course. This allowed us to include two crucial, but nontrivial, analysis methods: pre-flare baseline subtraction and computation of the flare energy, which requires determining flare start and stop times. We aggregated the results of these analyses into a statistical study to determine that $\alpha = 1.63 \pm 0.03$. This is below the critical threshold, suggesting that Alfv\'en waves are an important driver of coronal heating.Comment: 1,002 authors, 14 pages, 4 figures, 3 tables, published by The Astrophysical Journal on 2023-05-09, volume 948, page 7