A Simple Method Based on the Application of a CCD Camera as a Sensor to Detect Low Concentrations of Barium Sulfate in Suspension

The development of a simple, rapid and low cost method based on video image analysis and aimed at the detection of low concentrations of precipitated barium sulfate is described. The proposed system is basically composed of a webcam with a CCD sensor and a conventional dichroic lamp. For this purpose, software for processing and analyzing the digital images based on the RGB (Red, Green and Blue) color system was developed. The proposed method had shown very good repeatability and linearity and also presented higher sensitivity than the standard turbidimetric method. The developed method is presented as a simple alternative for future applications in the study of precipitations of inorganic salts and also for detecting the crystallization of organic compounds

Light in Thermal Environments (LITE) Workshop

Light emitted from high temperature black smokers (350 C) at mid-ocean ridge spreading centers has been documented, but the source of this light and its photochemical and biological consequences have yet to be investigated. Preliminary studies indicate that thermal radiation alone might account for the 'glow' and that a novel photoreceptor in shrimp colonizing black smoker chimneys may detect this 'glow.' A more controversial question is whether there may be sufficient photon flux of appropriate wavelengths to support geothermally-driven photosynthesis (GDP) by microorganisms. Although only a very low level of visible and near infrared light may be emitted from any single hydrothermal vent, several aspects of the light make it of more than enigmatic interest. First, the light is clearly linked to geophysical (and perhaps geochemical) processes; its attributes may serve as powerful index parameters for monitoring change in these processes. Second, while the glow at a vent orifice is a very local phenomenon, more expansive subsurface environments may be illuminated, thereby increasing the spatial scale at which biological consequences of this light might be considered. Third, in contrast to intermittent bioluminescent light sources in the deep sea, the light emitted at vents almost certainly glows or flickers continuously over the life of the individual black smokers (years to decades); collectively, light emitted from black smokers along the ocean's spreading centers superimposed on background Cerenkov radiation negates the concept of the deep sea as an environment devoid of abiotic light. Finally, the history of hydrothermal activity predates the origin of life; light in the deep sea has been a continuous phenomenon on a geological time scale and may have served either as a seed or refugium for the evolution of biological photochemical reactions or adaptations

Phosphorescent thermal history sensors for extreme environments

The measurement of the surface temperature of many components in gas turbines has become increasingly important as the firing temperature raises to improve thermal efficiency and reduce CO2 emissions. Traditional methods to measure temperatures in real time, such as thermocouples or pyrometers, are sometimes not suitable and an alternative must be sought. Thermal history sensors record the maximum temperatures reached during operation, which can then be measured after the engine has cooled down. Currently, temperature sensitive paints are mainly used to obtain temperature profiles on gas turbine components but they present some limitations such as subjectivity of the measurement, poor resolution and toxicity. Permanent changes in the optical properties of thermographic phosphors have been proposed as an alternative to record temperatures and can potentially overcome some of the difficulties associated with traditional paints. The changes in the optical properties of some europium doped phosphors after oxidation can be used to sense temperatures up to 1400 °C. The oxidation mechanism of BaMgAl10O17:Eu are investigated in detail by means of standard material characterisation techniques and laser induced phosphorescence. Variations in the luminescence properties of the phosphor (intensity ratio and lifetime decay) are related to microstructural and chemical changes and permitted to measure temperatures in the range 700 - 1200 °C. The influence of practical factors that can affect the measurement accuracy and sensitivity are thoroughly characterised. These include the energy fluence used for excitation, duration of the exposure at high temperatures, dopant concentration, time spent during cooling down, composition of the atmosphere during the heat treatment and particle size. The reversibility of the changes in the optical properties of the phosphor is studied by applying a heat treatment in a reducing atmosphere, and thus reusability of the sensor demonstrated. The development of a coating made of this phosphor is explored for the first time with regards to its application as a sensor. The difficulties to manufacture such a coating are mainly related to the complex stoichiometry and high processing temperature of the phosphor material. BaMgAl10O17:Eu coatings onto metallic substrates are manufactured by the screen printing method. In these coatings, diffusion of elements from the substrate undesirably affects the optical properties of the sensor after exposure to high temperatures. The use of a diffusion barrier permits to perform temperature measurements at temperatures up to 1100 °C comparable to the powder material. Thermal gradients across the ceramic coating can drastically affect the accuracy of the temperature measurements performed by using luminescence. Investigations in thermal barrier coating sensors in controlled gradient conditions are performed that permit evaluation of the temperature error introduced by these gradients. Comparison of experimental data and a theoretical model indicates that significant temperature measurement errors can be expected in BAM:Eu coatings when a thermal gradient is present.Open Acces

Pyroelectric Materials for Uncooled Infrared Detectors: Processing, Properties, and Applications

Uncooled pyroelectric detectors find applications in diverse and wide areas such as industrial production; automotive; aerospace applications for satellite-borne ozone sensors assembled with an infrared spectrometer; health care; space exploration; imaging systems for ships, cars, and aircraft; and military and security surveillance systems. These detectors are the prime candidates for NASA s thermal infrared detector requirements. In this Technical Memorandum, the physical phenomena underlying the operation and advantages of pyroelectric infrared detectors is introduced. A list and applications of important ferroelectrics is given, which is a subclass of pyroelectrics. The basic concepts of processing of important pyroelectrics in various forms are described: single crystal growth, ceramic processing, polymer-composites preparation, and thin- and thick-film fabrications. The present status of materials and their characteristics and detectors figures-of-merit are presented in detail. In the end, the unique techniques demonstrated for improving/enhancing the performance of pyroelectric detectors are illustrated. Emphasis is placed on recent advances and emerging technologies such as thin-film array devices and novel single crystal sensors

Using Fluorescence – Polarization Endoscopy in Detection of Precancerous and Cancerous Lesions in Colon and Pancreatic Cancer

Colitis-associated cancer (CAC) arises from premalignant flat lesions of the colon, which are difficult to detect with current endoscopic screening approaches. We have developed a complementary fluorescence and polarization reporting strategy that combines the unique biochemical and physical properties of dysplasia and cancer for real time detection of these lesions. Utilizing a new thermoresponsive sol-gel formulation with targeted molecular probe allowed topical application and detection of precancerous and cancerous lesions during endoscopy. Incorporation of nanowire-filtered polarization imaging into NIR fluorescence endoscopy served as a validation strategy prior to obtaining biopsies. In order to reduce repeat surgeries arising from incomplete tumor resection, we demonstrated the efficacy of the targeted molecular probe towards margins of sporadic colorectal cancer (SCC). Fluorescence-polarization microscopy using circular polarized (CP) light served as a rapid, supplementary tool for assessment and validation of excised tissue to ensure complete tumor resection for examining tumor margins prior to H&E-based pathological diagnosis. We extended our platform towards non-invasive directed detection of pancreatic cancer utilizing fluorescence molecular tomography (FMT) and NIR laparoscopy using identified targeted molecular probe. We were able to non-invasively distinguished between pancreatitis and pancreatic cancer and guide pancreatic tumor resection using NIR laparoscopy

Fifth International Conference on SALT WEATHERING OF BUILDINGS AND STONE SCULPTURES:

These proceedings report on the 5th edition of the conference, after Copenhagen (2008), Cyprus (2011), Brussel (2014) and Potsdam (2017), and it is the first time the conference is held in hybrid form, due to the COVID-19 pandemic. It is a challenge to organize an event in such an uncertain situation and to make it as attractive and interactive as the previous editions. We hope to meet your expectations! I’m very glad, that despite the situation, the interest for the conference is strong: we have received more than 40 contributions from 18 countries from all over the world. This confirms the relevance of the problem of salt weathering for the built cultural heritage and stone artifacts in a wide range of environments. Moreover, the broad spectrum of approaches to the subject presented in these proceedings highlights the importance of the interaction between different disciplines as well as between fundamental research and practice of conservation. I wish this conference to contribute to this fruitful exchange, and to generate new research ideas, whilst strengthening and broadening interdisciplinary collaborations. On behalf of the organizing committee, I’m looking forward to welcoming as many as possible of you in Delft. We hope that, next to participation to the conference, you will find some free time to visit the city. You can stroll along the canals, enter a windmill, visit the Prinsenhof museum and the Blue Delft Factory, admire the architecture and sculptures in the Old and New Church and, if you are looking for a real Dutch experience, you can rent a bicycle and visit the surroundings! This event would not have been possible without the collaboration of several persons. I would like to thank, on behalf of us all, the Scientific Committee for carefully reviewing the papers and contributing thereby to the high quality of the published contributions. My personal thank goes to the organizing committee who significantly contributed to the organization of this event and to the preparation of the proceedings. Last but not least, I’d like to thank the Cultural Heritage Agency of the Netherlands for co-sponsoring the event and RILEM (International Union of Laboratories and Experts in Construction Materials, Systems and Structures) for contributing to the dissemination

Analytical Development and Application of Optical Microcavities

Optical microcavities are desirable label-free sensors due to their sensitive detection capabilities. In particular, microsphere resonators achieve high sensitives by confining and recirculating light within their spherical cavity. Recirculation of light within these small, compact resonators amplifies sample-light interactions, contributing to improved sensing performance. By taking advantage of their desirable performance metrics, we have developed a variety of innovative label-free analytical platforms. For label-free biosensing, we have integrated whispering gallery mode (WGM) resonators with fluorescence imaging for the simultaneous analysis of multiple microspheres. Using this approach, we have demonstrated multiplexed detection of protein biomarkers. Current clinical tools used to diagnose ovarian cancer lack specificity and sensitivity required to achieve an accurate early diagnosis. Label-free platforms provide an opportunity to detect identified protein and non-protein disease biomarkers in order to improve diagnostic capabilities. Whispering gallery mode resonators offer a sensitive, multiplexed detection scheme to accomplish this. Specifically, our developed imaging approach allows multiple targets to be analyzed in a single assay by simultaneously monitoring WGM resonances of numerous microspheres. Microsphere resonators of particular sizes are functionalized for the detection of specific biomarkers. Putative ovarian cancer biomarkers CA-125, osteopontin, and prolactin were simultaneously quantified using WGM imaging. Additionally, the label-free platform was utilized for the detection of non-protein ovarian cancer target microRNA miR-142-3p. For biosensing applications, the small, compact size of microsphere resonators is also advantageous for integration with small volume systems. We demonstrate the incorporation of hundreds of WGM resonators in a 10 L droplet. By incorporating WGM resonators in small volume systems, such as microfluidic platforms, on-chip detection capabilities can be improved. In particular, digital microfluidic systems provide an analytical tool for precise control of discrete volume droplets, improving assay fluidics. In order to integrate WGM resonators with these small volume droplet systems, initial studies demonstrate real-time WGM detection in 10 L droplets. After determining evaporation was not an interferent, picomolar protein concentrations were measured by WGM resonators. Ultimately, these measurements can be extended to improve on-chip multiplexed immunoassay capabilities. To further explore WGM sensing applications, we developed a new analytical technique for label-free analysis of surfaces. Scanning resonator microscopy (SRM) utilizes a modified probe tip to analyze optical and topographic surface features. This novel scanning probe technique provides a label-free, non-invasive approach to investigate a variety of sample types. For material science applications, we demonstrate analysis of thin polymer films patterned by UV light using SRM. Additionally, we are interested in extending SRM measurements for the investigation of biological samples. Scanning resonator microscopy provides a label-free technique to measure protein coated surfaces, such as protein microarrays. Furthermore, for cell-based assays, label-free approaches allow for real time analysis of native biological systems. Initial investigations indicate SRM is a promising analytical tool for improving pre-clinical analysis methods for drug development and for applications in clinical diagnostics. Overall, WGM resonators are demonstrated as sensitive label-free detectors for the development of a variety of analytical tools

Raman and Surface Enhanced Raman Spectroscopy for Forensic Analysis: Case Studies on the Identification of Illicit Substances and Artist Pigments

Raman spectroscopy is an effective tool for detecting trace amounts of material by fingerprint-like vibrational spectra. At times, the weak intensity of Raman scattering can make it difficult to distinguish trace materials. This shortcoming is addressed by surface‐enhanced Raman spectroscopy (SERS), which produces strong signal enhancements when target compounds are near metal nanoparticles. For the first part of this thesis, the identification of fentanyl and carfentanil, main culprits in the opioid epidemic, was done using normal Raman and the SERS spectroscopy. As an aid in the assignment of the spectral lines, a computational model was built using Density Functional Theory (DFT). The enhancement factor (EF) obtained in this experiment is ≥ 1.6 x 105. The use of a paper-based substrate impregnated with silver nanoparticles for the detection of trace quantities of fentanyl alone, and as an adulterant in heroin and cocaine, was investigated. In addition, intensity ratios of diagnostic peaks associated with each substance were fitted to a Langmuir isotherm calibration model and used for quantitative analysis of fentanyl in heroin mixtures. Linearity was observed at \u3c 6% fentanyl, a significant finding that is consistent with concentrations found in drugs seized during law enforcement efforts. For trace quantities of fentanyl in cocaine, where it identified at a lower limit of 500 ng/mL in mixtures. Linear relationships were established between intensity and concentration for diagnostic peaks associated with fentanyl and cocaine. For the second part of this thesis, the applicability of normal Raman and SERS are presented in the context of a museum setting. The applicability of confocal and portable Raman is presented through the identification of : red pigments found in El Anatsui’s Bleeding Takari II; identification of the gouaches used by Henri Matisse in the Jazz album; and identification of the paints used by Jackson Pollock in Number 1A, 1948