Matching Items (41)

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Engineering of Arson Forensics and Fire Debris Investigation: The Scientific, Social, and Curricular Impact

Description

Arson and intentional fires account for significant property losses and over 400 civilian deaths yearly in the United States. However, clearance rates for arson offenses remain low relative to other

Arson and intentional fires account for significant property losses and over 400 civilian deaths yearly in the United States. However, clearance rates for arson offenses remain low relative to other crimes. This issue can be attributed in part to the challenges associated with performing an arson investigation, in particular the collection and interpretation of reliable data. PLOT-cryoadsorption, a dynamic headspace sampling technique developed at the National Institute of Standards and Technology, was proposed as an alternate technique for extracting ignitable liquid residues for analysis. The method was generally shown to be robust, flexible, precise, and accurate for a variety of applications. The possibility of using a real-time in situ monitor for screening samples was also discussed. This work, conducted by an undergraduate researcher, has implications in educational curricula as well as in the field of forensic science.

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Created

Date Created
  • 2013-05

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Walking Intervention Through Texting for Adolescents

Description

It is well established that physical activity (PA) directly correlates with many health benefits, especially when active habits are formed during childhood and adolescence. PA practiced in adolescence has been

It is well established that physical activity (PA) directly correlates with many health benefits, especially when active habits are formed during childhood and adolescence. PA practiced in adolescence has been seen to carry into adulthood, helping to combat a host of chronic diseases, such as obesity and diabetes. However, in recent years there has been a steady decline in PA among adolescents, followed by a resulting rise in sedentary behavior. Walking Intervention Through Texting for Adolescents, or WalkIT-A, was an 11.5-week intervention that built upon behavioral theory to provide an incentive-based, adaptive, physical activity intervention to inactive adolescents. The goal of this study was to investigate an intervention which combined walking with pointed behavior change strategies to incite a larger increase in PA. Using single-case, reversal (ABA) design, the study was aimed at shaping physical activity behavior in adolescents aged 12-17 through a mobile health intervention that paired adaptive goal setting with financial incentives to increase step count. The intervention was delivered using a semi-automated texting, mobile-Health (mHealth) platform, which incorporated FitBit tracking technology, adaptive goals, motivational messages, performance feedback, and points/incentives. It was hypothesized that during the adaptive intervention phase participants would increase both steps per day and active minutes compared to baseline values. Upon conclusion of the study, the three adolescent participants exhibited increased steps and active minutes during the intervention period compared to baseline and withdrawal phases. However, the specific trends identified suggest the need for future research to incorporate even stronger intervention components to overcome PA "drop-off" midway through the intervention, along with other external, environmental influencers. Despite this need, the use of adaptive goal setting combined with incentives can be an effective means to incite PA behavior change in adolescents.

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Created

Date Created
  • 2016-12

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Optimization of Packaging Conditions for Long-term Stability of Colorimetric Carbon Dioxide Sensors for Capnography Applications in Non-intubated Patients

Description

Capnography is the monitoring of concentrations of carbon dioxide in exhaled breath. It allows reliable insight into patients' metabolism, ventilation, and blood circulation. Capnography has become an integral part of

Capnography is the monitoring of concentrations of carbon dioxide in exhaled breath. It allows reliable insight into patients' metabolism, ventilation, and blood circulation. Capnography has become an integral part of anesthesiology monitoring in operating rooms. However, its used is limited in other contexts due to deeply engrained protocols, size of capnographs, and the complexity of its interpretation. Intensive care units and in-home use could greatly benefit by a widespread usage of capnographs. Measuring methods include infrared spectroscopy, mass spectroscopy, and chemical colorimetric analysis. Infrared technology is currently the most widely used and cost-effective method for measuring carbon dioxide. However, this device can be bulky and costly. A novel portable breath CO2 analyzer was developed for this purpose. The analyzer features an accurate colorimetric CO2 sensor that can analyze ETCO2 in real time. Many advancements have been in made in the sensor fabrication process. Nevertheless, research on optimal packaging conditions and accelerated aging times have been limited. In this experiment, carbon dioxide sensors were packaged at four different environmental conditions to test their long-term stability. This was done to determine if these conditions had an effect on sensor degradation. In the second part of the experiment, a separate batch of sensors was placed inside an oven at 48 oC to investigate the effect of stabilization temperature dependence and accelerated aging. In conclusion, the data obtained from the sensors packaged at different conditions could not be concluded to be statistically different. Sensors packaged at ambient conditions had the highest average value at 0.45030 V and the ones at controlled 33% humidity had the lowest at 0.39348 V. The sensors packaged at 8.25% CO2 had the smallest variance in their voltage measurements. From these data, it can be concluded that environmental testing conditions had the greatest effect on the measured signal. The oven experiment showed that sensors rapidly stabilize at high temperature and these stay constant after reaching this stabilization. For future work, the signal difference at different environmental conditions should be done. Control of environmental conditions can be achieved by building a glove box to control temperature and humidity.

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Created

Date Created
  • 2015-05

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Thermochemical Humidity Detection in Harsh or Non-Steady Environments

Description

We present a new method of chemical quantification utilizing thermal analysis for the detection of relative humidity. By measuring the temperature change of a hydrophilically-modified temperature sensing element vs. a

We present a new method of chemical quantification utilizing thermal analysis for the detection of relative humidity. By measuring the temperature change of a hydrophilically-modified temperature sensing element vs. a hydrophobically-modified reference element, the total heat from chemical interactions in the sensing element can be measured and used to calculate a change in relative humidity. We have probed the concept by assuming constant temperature streams, and having constant reference humidity (~0% in this case). The concept has been probed with the two methods presented here: (1) a thermistor-based method and (2) a thermographic method. For the first method, a hydrophilically-modified thermistor was used, and a detection range of 0–75% relative humidity was demonstrated. For the second method, a hydrophilically-modified disposable surface (sensing element) and thermal camera were used, and thermal signatures for different relative humidity were demonstrated. These new methods offer opportunities in either chemically harsh environments or in rapidly changing environments. For sensing humidity in a chemically harsh environment, a hydrophilically-modified thermistor can provide a sensing method, eliminating the exposure of metallic contacts, which can be easily corroded by the environment. On the other hand, the thermographic method can be applied with a disposable non-contact sensing element, which is a low-cost upkeep option in environments where damage or fouling is inevitable. In addition, for environments that are rapidly changing, the thermographic method could potentially provide a very rapid humidity measurement as the chemical interactions are rapid and their changes are easily quantified.

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Created

Date Created
  • 2017-05-24

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A Novel Wireless Wearable Volatile Organic Compound (VOC) Monitoring Device with Disposable Sensors

Description

A novel portable wireless volatile organic compound (VOC) monitoring device with disposable sensors is presented. The device is miniaturized, light, easy-to-use, and cost-effective. Different field tests have been carried out

A novel portable wireless volatile organic compound (VOC) monitoring device with disposable sensors is presented. The device is miniaturized, light, easy-to-use, and cost-effective. Different field tests have been carried out to identify the operational, analytical, and functional performance of the device and its sensors. The device was compared to a commercial photo-ionization detector, gas chromatography-mass spectrometry, and carbon monoxide detector. In addition, environmental operational conditions, such as barometric change, temperature change and wind conditions were also tested to evaluate the device performance. The multiple comparisons and tests indicate that the proposed VOC device is adequate to characterize personal exposure in many real-world scenarios and is applicable for personal daily use.

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Created

Date Created
  • 2016-12-03

Acetone as Biomarker for Ketosis Buildup Capability: A Study in Healthy Individuals Under Combined High Fat and Starvation Diets

Description

Background:
Ketogenic diets are high fat and low carbohydrate or very low carbohydrate diets, which render high production of ketones upon consumption known as nutritional ketosis (NK). Ketosis is also

Background:
Ketogenic diets are high fat and low carbohydrate or very low carbohydrate diets, which render high production of ketones upon consumption known as nutritional ketosis (NK). Ketosis is also produced during fasting periods, which is known as fasting ketosis (FK). Recently, the combinations of NK and FK, as well as NK alone, have been used as resources for weight loss management and treatment of epilepsy.

Methods:
A crossover study design was applied to 11 healthy individuals, who maintained moderately sedentary lifestyle, and consumed three types of diet randomly assigned over a three-week period. All participants completed the diets in a randomized and counterbalanced fashion. Each weekly diet protocol included three phases: Phase 1 - A mixed diet with ratio of fat: (carbohydrate + protein) by mass of 0.18 or the equivalence of 29% energy from fat from Day 1 to Day 5. Phase 2- A mixed or a high-fat diet with ratio of fat: (carbohydrate + protein) by mass of approximately 0.18, 1.63, or 3.80 on Day 6 or the equivalence of 29%, 79%, or 90% energy from fat, respectively. Phase 3 - A fasting diet with no calorie intake on Day 7. Caloric intake from diets on Day 1 to Day 6 was equal to each individual’s energy expenditure. On Day 7, ketone buildup from FK was measured.

Results:
A statistically significant effect of Phase 2 (Day 6) diet was found on FK of Day 7, as indicated by repeated analysis of variance (ANOVA), F(2,20) = 6.73, p < 0.0058. Using a Fisher LDS pair-wise comparison, higher significant levels of acetone buildup were found for diets with 79% fat content and 90% fat content vs. 29% fat content (with p = 0.00159**, and 0.04435**, respectively), with no significant difference between diets with 79% fat content and 90% fat content. In addition, independent of the diet, a significantly higher ketone buildup capability of subjects with higher resting energy expenditure (R[superscript 2] = 0.92), and lower body mass index (R[superscript 2] = 0.71) was observed during FK.

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Created

Date Created
  • 2015-04-22

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Colorimetric Humidity Sensor Based on Liquid Composite Materials for the Monitoring of Food and Pharmaceuticals

Description

Using supported ionic-liquid membrane (SILM)-inspired methodologies, we have synthesized, characterized, and developed a humidity sensor by coating a liquid composite material onto a hygroscopic, porous substrate. Similar to pH paper,

Using supported ionic-liquid membrane (SILM)-inspired methodologies, we have synthesized, characterized, and developed a humidity sensor by coating a liquid composite material onto a hygroscopic, porous substrate. Similar to pH paper, the sensor responds to the environment’s relative humidity and changes color accordingly. The humidity indicator is prepared by casting a few microliters of low-toxicity reagents on a nontoxic substrate. The sensing material is a newly synthesized liquid composite that comprises a hygroscopic medium for environmental humidity capture and a color indicator that translates the humidity level into a distinct color change. Sodium borohydride was used to form a liquid composite medium, and DenimBlu30 dye was used as a redox indicator. The liquid composite medium provides a hygroscopic response to the relative humidity, and DenimBlu30 translates the chemical changes into a visual change from yellow to blue. The borate–redox dye-based humidity sensor was prepared, and then Fourier transform infrared spectroscopy, differential scanning calorimetry, and image analysis methods were used to characterize the chemical composition, optimize synthesis, and gain insight into the sensor reactivity. Test results indicated that this new sensing material can detect relative humidity in the range of 5–100% in an irreversible manner with good reproducibility and high accuracy. The sensor is a low-cost, highly sensitive, easy-to-use humidity indicator. More importantly, it can be easily packaged with products to monitor humidity levels in pharmaceutical and food packaging.

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Agent

Created

Date Created
  • 2014-09-09

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Temperature dependency on baseline of polymer modified Tuning Forks

Description

Polymer modified tuning fork-based sensors were fabricated to assure reproducibility. The effect of system valve switching on the modified tuning fork-based sensors was studied at the different temperature. The response

Polymer modified tuning fork-based sensors were fabricated to assure reproducibility. The effect of system valve switching on the modified tuning fork-based sensors was studied at the different temperature. The response to Xylene gas sample on stabilized modified tuning fork-based sensors with temperature was defined while learning about the key analytical performance for chemical sensors to be used in the real-world application.

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Created

Date Created
  • 2017-05

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Advancing microfluidic-based protein biosensor technology for use in clinical diagnostics

Description

Demand for biosensor research applications is growing steadily. According to a new report by Frost & Sullivan, the biosensor market is expected to reach $14.42 billion by 2016. Clinical diagnostic

Demand for biosensor research applications is growing steadily. According to a new report by Frost & Sullivan, the biosensor market is expected to reach $14.42 billion by 2016. Clinical diagnostic applications continue to be the largest market for biosensors, and this demand is likely to continue through 2016 and beyond. Biosensor technology for use in clinical diagnostics, however, requires translational research that moves bench science and theoretical knowledge toward marketable products. Despite the high volume of academic research to date, only a handful of biomedical devices have become viable commercial applications. Academic research must increase its focus on practical uses for biosensors. This dissertation is an example of this increased focus, and discusses work to advance microfluidic-based protein biosensor technologies for practical use in clinical diagnostics. Four areas of work are discussed: The first involved work to develop reusable/reconfigurable biosensors that are useful in applications like biochemical science and analytical chemistry that require detailed sensor calibration. This work resulted in a prototype sensor and an in-situ electrochemical surface regeneration technique that can be used to produce microfluidic-based reusable biosensors. The second area of work looked at non-specific adsorption (NSA) of biomolecules, which is a persistent challenge in conventional microfluidic biosensors. The results of this work produced design methods that reduce the NSA. The third area of work involved a novel microfluidic sensing platform that was designed to detect target biomarkers using competitive protein adsorption. This technique uses physical adsorption of proteins to a surface rather than complex and time-consuming immobilization procedures. This method enabled us to selectively detect a thyroid cancer biomarker, thyroglobulin, in a controlled-proteins cocktail and a cardiovascular biomarker, fibrinogen, in undiluted human serum. The fourth area of work involved expanding the technique to produce a unique protein identification method; Pattern-recognition. A sample mixture of proteins generates a distinctive composite pattern upon interaction with a sensing platform consisting of multiple surfaces whereby each surface consists of a distinct type of protein pre-adsorbed on the surface. The utility of the "pattern-recognition" sensing mechanism was then verified via recognition of a particular biomarker, C-reactive protein, in the cocktail sample mixture.

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Agent

Created

Date Created
  • 2011

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Pressure based spirometry: mobile spirometry using a pressure transducer

Description

Spirometry is a type of pulmonary function test that measures the amount of air volume and the speed of air flow from a patient's breath in order to assess lung

Spirometry is a type of pulmonary function test that measures the amount of air volume and the speed of air flow from a patient's breath in order to assess lung function. The goal of this project is to develop and validate a mobile spirometer technology based on a differential pressure sensor. The findings in this paper are used in a larger project that combines the features of a capnography device and a spirometer into a single mobile health unit known as the capno-spirometer. The following paper discusses the methods, experiments, and prototypes that were developed and tested in order to create a robust and accurate technology for all of the spirometry functions within the capno-spirometer. The differential pressure sensor is set up with one inlet measuring the pressure inside the spirometer tubing and the other inlet measuring the ambient pressure of the environment. The inlet measuring the inside of the tubing is very sensitive to its orientation and position with respect to the path of the air flow. It is found that taking a measurement from the center of the flow is 50% better than from the side wall. The sensor inlet is optimized at 37 mm from the mouthpiece inlet. The unit is calibrated by relating the maximum pressure sensor voltage signal to the peak expiratory flow rate (PEF) taken during a series of spirometry tests. In conclusion, this relationship is best represented as a quadratic function and a calibration equation is computed to provide a flow rate given a voltage change. The flow rates are used to calculate the four main spirometry parameters: PEF, FVC, FEV1, and FER. These methods are then referenced with the results from a commercial spirometer for validation. After validation, the pressure-based spirometry technology is proven to be both robust and accurate.

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Agent

Created

Date Created
  • 2013