Effects of Corrosion on the SERS Activity and Optical Response of Silver Nanorods

The nanoscience and nanotechnology community have a common goal in better understanding the surfaced enhanced Raman scattering (SERS) that occurs due to laser plasmon resonance in conjunction with metal enhanced substrates. Metallic nanostructures, such as silver (Ag) nanorods, are widely used in biological and chemical sensing applications that rely on the measurement of subtle changes in the optical response of the nanostructures in the presence of a target agent. The optical response of Ag nanorods and most other metallic nanostructures is highly sensitive to morphology and surface chemical termination. In pristine condition, the optical properties of Ag nanorods and other metallic nanostructures are well documented in the literature. However, almost nothing is known of the structure – property effects of exposure to solvents, buffered solutions, and similar in real applications. This document reports on the investigation into the effects of dissolved gasses, which are known to corrode bulk and thin film silver (Ag), in di-ionized water on Ag nanorods. Through SEM, SPM, UV-Vis, and Raman Spectroscopy, characterization of rapid corrosion and morphological changes are observed within minutes when Ag nanorods are exposed to water with dissolved gases present. Conversely, almost no measurable changes are observed when the dissolved gases are removed from the water via boiling. The current research attempts in exploiting the enhancement factors of optical properties dealing with SERS. Growing substrates to examine in SERS by using physical vapor deposition (PVD) on corning glass depositing Ag nanorods will enlighten the nanoscience and nanotechnology community on these changes in optical properties. SPM and SEM images both show significant differences through corrosion of Ag on the two different types of water. The species from corrosion in regular water appears to be AgO, as there is no Sulphur detected by the SEM’s EDS spectrum. KFM shows clear differences in surface potential indicating a chemical change. UV-Vis shows a decrease in resonance and absorptivity after corroding. The goal of this investigation is to characterize oxidation species grown on the Ag nanorods when the substrate is exposed to O and dissolved gasses. Raman Spectrum shows that for a fluorescent molecule (R6G), the overall measured Raman signal significantly increases with oxidation due to activation of surface enhanced fluorescence. Statistical T-test were run on spectrum, a value of 1.83E-05 was accessed to prove the significant increase in signal. When oxidation occurs from substrates stored in water with dissolved gases like the R6G samples, the scatter in the signal also significantly increases, proven with an f-test value of 4.76E-05. Additionally, when a non-resonant molecule is used, like our caffeine, the scatter in signal significantly increases, proven by f-test value of 2.4E-02. By experimenting contrasting substrate-samples during Raman that were taken straight out of vacuum or stored in water, the community can see the indicating affect measured in Raman spectra

Foreword

This issue of the Annual Survey of Virginia Law is very special. It completes volume twenty-five of the University of Richmond Law Review. Initially, the Law Review was published by the faculty. However, the publication of volume three marked the beginning of the Law Review as a student-run publication

A simplified and scalable should-cost tool in the oilfield services industry

Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 55-57).Third party spend accounts for a significant amount of a business' costs. When procuring unique, highly-engineered components, this cost is often negotiated with suppliers during the procurement process. Due to the limited understanding of the suppliers' true production cost, various techniques and models for determining how much a procured product should cost have been tried. One such approach is known as "should-cost modeling," where estimates for the cost of a product or service are made based on product architecture and/or firm financials. Both these approaches to should-cost modeling require extensive data collection and are time consuming. In this thesis, we expand an approach that uses aggregate industry-specific financial data to develop a simple, scalable tool to estimate a product's should-cost. One major challenge in building this tool is unifying the simple aggregate data available into an estimated price for a complex product. This is a major challenge of developing a should-cost estimate using existing methods. We develop an approach to simplifying a complex product, construct our model, and create a ready-to-use tool. We demonstrate the working of the model and the tool using the case of a semi-complex product (the fluid end of a pump) representative of a company's procured products. We then compare the price estimated by our model with that currently negotiated with our sponsor company's supplier and solicit qualitative feedback from procurement professionals regarding the should-cost tool's accuracy. The price estimated by our tool is within 9% of the actual negotiated price and required significantly less time to compute compared to the current approach based on product architecture. The company's sourcing and procurement executive strongly endorses the benefits of our approach. This tool can remove the reliance on supplier-supplied quotes and strengthen the purchasing company's negotiating position. The tool developed in this thesis is shown to provide a more accurate estimate of product cost, with significantly less estimation effort.by Clayton M. Mealer and Sung Hwan Park.M.Eng.in Logistic

Radiative Heat Transfer Analysis of Railroad Bearings for Wayside Hot-Box Detector Optimization

The railroad industry utilizes wayside detection systems to monitor the temperature of freight railcar bearings in service. The wayside hot-box detector (HBD) is a device that sits on the side of the tracks and uses a non-contact infrared sensor to determine the temperature of the train bearings as they roll over the detector. Various factors can affect the temperature measurements of these wayside detection systems. The class of the railroad bearing and its position on the axle relative to the position of the wayside detector can affect the temperature measurement. That is, the location on the bearing cup where the wayside infrared sensor reads the temperature varies depending on the bearing class (e.g., class K, F, G, E). Furthermore, environmental factors can also affect these temperature readings. The abovementioned factors can lead to measured temperatures that are significantly different than the actual operating temperatures of the bearings. In some cases, temperature readings collected by wayside detection systems did not indicate potential problems with some bearings, which led to costly derailments. Attempts by certain railroads to optimize the use of the temperature data acquired by these wayside detection systems has led to removal of bearings that were not problematic (about 40% of bearings removed were non-verified), resulting in costly delays and inefficiencies. To this end, the study presented here aims to investigate the efficacy of the wayside detection systems in measuring the railroad bearing operating temperature in order to optimize the use of these detection systems. A specialized single bearing dynamic test rig with a configuration that closely simulates the operating conditions of railroad bearings in service was designed and built by the University Transportation Center for Railway Safety (UTCRS) research team at the University of Texas Rio Grande Valley (UTRGV) for the purpose of this study. The test rig is equipped with a system that closely mimics the wayside detection system functionality and compares the infrared sensor temperature reading to contact thermocouple and bayonet temperature sensors fixed to the outside surface of the bearing cup. This direct comparison of the temperature data will provide a better understanding of the correlation between these temperatures under various loading levels, operating speeds, and bearing conditions (i.e. healthy versus defective), which will allow for an optimization of the wayside detectors. The impact on railway safety will be realized through optimized usage of current wayside detection systems and fewer nonverified bearings removed from service, which translates into fewer costly train stoppages and delays

Extravascular lung water in patients with severe sepsis: a prospective cohort study

INTRODUCTION: Few investigations have prospectively examined extravascular lung water (EVLW) in patients with severe sepsis. We sought to determine whether EVLW may contribute to lung injury in these patients by quantifying the relationship of EVLW to parameters of lung injury, to determine the effects of chronic alcohol abuse on EVLW, and to determine whether EVLW may be a useful tool in the diagnosis of acute respiratory distress syndrome (ARDS). METHODS: The present prospective cohort study was conducted in consecutive patients with severe sepsis from a medical intensive care unit in an urban university teaching hospital. In each patient, transpulmonary thermodilution was used to measure cardiovascular hemodynamics and EVLW for 7 days via an arterial catheter placed within 72 hours of meeting criteria for severe sepsis. RESULTS: A total of 29 patients were studied. Twenty-five of the 29 patients (86%) were mechanically ventilated, 15 of the 29 patients (52%) developed ARDS, and overall 28-day mortality was 41%. Eight out of 14 patients (57%) with non-ARDS severe sepsis had high EVLW with significantly greater hypoxemia than did those patient with low EVLW (mean arterial oxygen tension/fractional inspired oxygen ratio 230.7 ± 36.1 mmHg versus 341.2 ± 92.8 mmHg; P < 0.001). Four out of 15 patients with severe sepsis with ARDS maintained a low EVLW and had better 28-day survival than did ARDS patients with high EVLW (100% versus 36%; P = 0.03). ARDS patients with a history of chronic alcohol abuse had greater EVLW than did nonalcoholic patients (19.9 ml/kg versus 8.7 ml/kg; P < 0.0001). The arterial oxygen tension/fractional inspired oxygen ratio, lung injury score, and chest radiograph scores correlated with EVLW (r(2 )= 0.27, r(2 )= 0.18, and r(2 )= 0.28, respectively; all P < 0.0001). CONCLUSIONS: More than half of the patients with severe sepsis but without ARDS had increased EVLW, possibly representing subclinical lung injury. Chronic alcohol abuse was associated with increased EVLW, whereas lower EVLW was associated with survival. EVLW correlated moderately with the severity of lung injury but did not account for all respiratory derangements. EVLW may improve both risk stratification and management of patients with severe sepsis

Can We Predict Burnout among Student Nurses? An Exploration of the ICWR-1 Model of Individual Psychological Resilience

The nature of nursing work is demanding and can be stressful. Previous studies have shown a high rate of burnout among employed nurses. Recently, efforts have been made to understand the role of resilience in determining the psychological adjustment of employed nurses. A theoretical model of resilience was proposed recently that includes several constructs identified in the literature related to resilience and to psychological functioning. As nursing students are the future of the nursing workforce it is important to advance our understanding of the determinants of resilience in this population. Student nurses who had completed their final practicum were invited to participate in an online survey measuring the key constructs of the ICWR-1 model. 422 students from across Australia and Canada completed the survey between July 2014 and July 2015. As well as several key demographics, trait negative affect, mindfulness, self-efficacy, coping, resilience, and burnout were measured. We used structural equation modeling and found support for the major pathways of the model; namely that resilience had a significant influence on the relationship between mindfulness, self-efficacy and coping, and psychological adjustment (burnout scores). Furthermore, as predicted, Neuroticism moderated the relationship between coping and burnout. Results are discussed in terms of potential approaches to supporting nursing students who may be at risk of burnout

An integrative review of the impact of indirect trauma exposure in health professionals and potential issues of salience for midwives

Aims: To explore responses to indirect trauma reported by health professionals and to identify issues of potential salience for midwives. Background: Indirect exposure to a traumatic event can lead to the development of distressing and potentially enduring responses. Little is understood about the impact that perinatal trauma exposure could have on midwives. Design: An integrative review design was used. Data sources: PsychInfo, Medline, PsychArticles, Web of Knowledge, CINAHL, MIDIRS and Scopus databases were search for papers published between 1980–November 2012. Review methods: Studies providing quantitative or qualitative exploration of healthcare professionals' responses to indirectly experienced traumatic events were selected. Results: Forty‐two papers fulfilled the inclusion criteria. Four of these studies included professionals engaged in maternity care or exposed to traumatic perinatal events. Findings indicate evidence of intrusion, avoidance and arousal in healthcare professionals, with differing degrees of frequency. Empathy, work‐related stress and the extent of professional experience were identified as associated with traumatic stress responses. Conclusions: Evidence derived from healthcare professionals suggests that indirect exposure to the traumatic events of recipients of care can sometimes elicit traumatic stress responses. Factors increasing risk for traumatic stress were identified as empathy and organizational stress. These factors hold specific salience in midwifery. Responding to trauma in a midwifery context, as informed by findings from other healthcare professionals, could adversely affect midwives' well‐being, care provided to women and contribute to an adverse organizational climate. Large‐scale research considering the experiences of midwives is recommended