Nanofabrication via laser interference lithography and integration of various optical systems for remote sensing applications

Nanophotonic devices help to manipulate light at nanometric scale through various optical phenomena in near infrared and visible regions of the electromagnetic spectrum. This research aims to present the fabrication, modelling, optical characterisation and real life applications of optical devices based on materials such as ink, soft polymer, gelatine, leuco dye and liquid crystals. Laser interference-based ablation is utilised to generate phase conjugate nanostructures on ink, gelatine based edible nanostructures for food decoration purposes, and flexible polymeric nanostructures on polydimethylsiloxane substrate to demonstrate their use for remote sensing applications. Replication of Cornercube Retroreflector array and diffusing surface is conducted in this research to construct flexible force and temperature sensors. CCRs are mainly exploited in this research due to their retroreflection property. Reflected light from CCRs is sent back towards the source through total internal reflection and is independent of the incident angle. A silver coated CCR is used to fabricate a 2D conjugate periodic gratings structure on ink coated glass substrate through Denisyuk reflection holography. Diffractive gratings (super prism) fabricated from simple mirror-based interference reflection have less features to manipulate as compared to the conjugate diffractive gratings made by using interference obtained from CCRs. Nanometric holographic CCR showed somewhat similar optical properties as shown by master centimetric CCR e.g. phase conjugation. Predictions through computational modelling were also in good agreement with the experimental (optical characterisation) results. CCR array structures are most commonly encountered in everyday life activities such as traffic signals, vehicle safety systems and nightwear clothing. The use of brittle optical devices is limited due to their rigidity. In this research, PDMS was used to replicate rigid CCRs array structures into a flexible form. Polymeric CCRs array was examined and compared to the stencil by utilising optical microscopy. Optical characterisations were performed under various mechanical and thermal stress levels. Optical properties dependent on structure’s dimension were tuned based on the external stimuli such as force. It is concluded in this study that polymeric optical structures have a potential to be employed in numerous sensing applications for stretch, temperature, pH, and humidity. Combination of CCRs and thermochromatic materials can yield remote temperature sensors based on active components. This research also demonstrates two different systems including liquid crystals and leuco dyes to record temperature changes within a region of interest. Glass based CCRs were coated with leuco dye and liquid crystals and were treated at various known temperatures under continuous monochromatic light illumination. Reflected power from thermochromatic CCR was tuned based on supplied temperature and was found to be dependent on the colour scheme. These novel systems may help to monitor environmental conditions such as temperature changes within hazardous areas, where human access is restricted. Finally, edible, flexible and multi-layered materials were engineered with photonic structures to examine the flexibility of Nd:YAG laser ablation in Denisyuk reflection mode. Fabricated structures were examined by scanning electron microscopy and optically characterised with monochromatic and broadband light sources. Various shapes of nanostructures were achieved by utilising provided parameters for fabrication. It is hence concluded that laser interference-based ablation is simple, fast, cost-effective and flexible technique to copy reflective objects in nanometric scale

Agarose-based structured optical fibre

Biocompatible and resorbable optical fibres emerge as promising technologies for in vivo applications like imaging, light delivery for phototherapy and optogenetics, and localised drug-delivery, as well as for biochemical sensing, wherein the probe can be implanted and then completely absorbed by the organism. Biodegradable waveguides based on glasses, hydrogels, and silk have been reported, but most of these devices rely on complex fabrication procedures. In this sense, this paper proposes a novel structured optical fibre made of agarose, a transparent, edible material used in culture media and tissue engineering. The fibre is obtained by pouring food-grade agar into a mould with stacked rods, forming a solid core surrounded by air holes in which the refractive index and fibre geometry can be tailored by choosing the agarose solution composition and mould design, respectively. Besides exhibiting practical transmittance at 633 nm in relation to other hydrogel waveguides, the fibre is also validated for chemical sensing either by detecting volume changes due to agar swelling/dehydration or modulating the transmitted light by inserting fluids into the air holes. Therefore, the proposed agarose-based structured optical fibre is an easy-to-fabricate, versatile technology with possible applications for medical imaging and in vivo biochemical sensing101CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão temNão tem2017/25666-

A smartphone-based chemosensor to evaluate antioxidants in agri-food matrices by in situ AuNP formation

In recent years, there has been a continuously growing interest in antioxidants by both customers and food industry. The beneficial health effects of antioxidants led to their widespread use in fortified functional foods, as dietary supplements and as preservatives. A variety of analytical methods are available to evaluate the total antioxidant capacity (TAC) of food extracts and beverages. However, most of them are expensive, time-consuming, and require laboratory instrumentation. Therefore, simple, cheap, and fast portable sensors for point-of-need measurement of antioxidants in food samples are needed. Here, we describe a smartphone-based chemosensor for on-site assessment of TAC of aqueous matrices, relying on the antioxidant-induced formation of gold nanoparticles. The reaction takes place in ready-to-use analytical cartridges containing an hydrogel reaction medium preloaded with Au(III) and is monitored by using the smartphone’s CMOS camera. An analytical device including an LED-based lighting system was developed to ensure uniform and reproducible illumination of the analytical cartridge. The chemosensor permitted rapid TAC measurements of aqueous samples, including teas, herbal infusions, beverages, and extra virgin olive oil extracts, providing results that correlated with those of the reference methods for TAC assessment, e.g., oxygen radical absorbance capacity (ORAC)

Solar System Exploration Research Virtual Institute: Year Three Annual Report 2016

NASA's Solar System Exploration Research Virtual Institute (SSERVI) is pleased to present the 2016 Annual Report. Each year brings new scientific discoveries, technological breakthroughs, and collaborations. The integration of basic research and development, industry and academic partnerships, plus the leveraging of existing technologies, has further opened a scientific window into human exploration. SSERVI sponsorship by the NASA Science Mission Directorate (SMD) and Human Exploration and Operations Mission Directorate (HEOMD) continues to enable the exchange of insights between the human exploration and space science communities, paving a clearer path for future space exploration. SSERVI provides a unique environment for scientists and engineers to interact within multidisciplinary research teams. As a virtual institute, the best teaming arrangements can be made irrespective of the geographical location of individuals or laboratory facilities. The interdisciplinary science that ensues from virtual and in-person interactions, both within the teams and across team lines, provides answers to questions that many times cannot be foreseen. Much of this research would not be accomplished except for the catalyzing, collaborative environment enabled by SSERVI. The SSERVI Central Office, located at NASA Ames Research Center in Silicon Valley, California, provides the leadership, guidance and technical support that steers the virtual institute. At the start of 2016, our institute had nine U.S. teams, each mid-way through their five-year funding cycle, plus nine international partnerships. However, by the end of the year we were well into the selection of four new domestic teams, selected through NASA's Cooperative Agreement Notice (CAN) process, and a new international partnership. Understanding that human and robotic exploration is most successful as an international endeavor, international partnerships collaborate with SSERVI domestic teams on a no-exchange of funds basis, but they bring a richness to the institute that is priceless. The international partner teams interact with the domestic teams in a number of ways, including sharing students, scientific insights, and access to facilities. We are proud to introduce our newest partnership with the Astrophysics and Planetology Research Institute (IRAP) in Toulouse, France. In 2016, Principal Investigator Dr. Patrick Pinet assembled a group of French researchers who will contribute scientific and technological expertise related to SSERVI research. SSERVI's domestic teams compete for five-year funding opportunities through proposals to a NASA CAN every few years. Having overlapping proposal selection cycles allows SSERVI to be more responsive to any change in direction NASA might experience, while providing operational continuity for the institute. Allowing new teams to blend with the more seasoned teams preserves corporate memory and expands the realm of collaborative possibilities. A key component of SSERVI's mission is to grow and maintain an integrated research community focused on questions related to the Moon, Near-Earth asteroids, and the moons of Mars. The strong community response to CAN-2 demonstrated the health of that effort. NASA Headquarters conducted the peer-review of 22 proposals early in 2017 and, based on recommendations from the SSERVI Central Office and NASA SSERVI program officers, the NASA selecting officials determined the new teams in the spring of 2017. We are pleased to welcome the CAN-2 teams into the institute, and look forward to the collaborations that will develop with the current teams. The new teams are: The Network for Exploration and Space Science (NESS) team (Principal Investigator (PI) Prof. Jack Burns/U. Colorado); the Exploration Science Pathfinder Research for Enhancing Solar System Observations (ESPRESSO) team (PI Dr. Alex Parker/Southwest Research Institute); the Toolbox for Research and Exploration (TREX) team (PI Dr. Amanda Hendrix/ Planetary Science Institute); and the Radiation Effects on Volatiles and Exploration of Asteroids & Lunar Surfaces (REVEALS) team (PI Prof. Thomas Orlando/ Georgia Institute of Technology). In this report, you will find an overview of the 2016 leadership activities of the SSERVI Central Office, reports prepared by the U.S. teams from CAN-1, and achievements from several of the SSERVI international partners. Reflecting on the past year's discoveries and advancements serves as a potent reminder that there is still a great deal to learn about NASA's target destinations. Innovation in the way we access, sample, measure, visualize, and assess our target destinations is needed for further discovery. At the same time, let us celebrate how far we have come, and strongly encourage a new generation that will make the most of future opportunities

Greenhouse Gas Emissions From Two Contrasting Beef Systems from Birth to Slaughter in Eastern Nebraska

Over the last 15 years, the increase in land use for corn and soybean has come at the expense of acres of grasslands and perennial forages employed in conventional beef-production systems. Implementing alternative cow-calf production systems into existing cropping systems may be a solution for reduced land availability and reducing total greenhouse gas emissions (GHG). Therefore, GHG from a conventional (CONV) pasture-based cattle production system with cows wintered on corn residue and summer grazing of brome pasture were compared to partial-confinement system (ALT) with cows and calves in a drylot during the summer and grazing cover crops and corn residue over the fall and winter. Eddy covariance and pen chambers were used to measure emissions from grazing and confinement scenarios. Measured CH4 and modeled N2O emissions totaled 7.5 ± 0.3 and 7.4 ± 0.3 kg CO2e kg-1 HCW for CONV and ALT production, respectively. There was a measured uptake of 233 g C m-2 and 98 g C m-2 from brome pasture and cover crop, respectively. Accounting for CH4 and N2O emissions using global warming potential (GWP) of 23 and 298 resulted in a net sink of 0.7 ± 0.2 kg CO2e kg-1 HCW for CONV and a net source of 16.7 ± 1.5 kg CO2e kg-1 HCW for ALT. The same calculations using global warming potential (GWP) of 4 and 234 resulted in a net sink of 10.9 ± 1.0 kg CO2e kg-1 HCW for CONV and a net source of 7.1 ± 1.5 kg CO2e kg-1 HCW for ALT. Carbon sequestration from perennial grasslands in the CONV was enough to offset all emissions and biogenic CO2. Annual forage grazed in the ALT system offset 42 to 72% of systems emissions depending on GWP metric used. These net carbon results open new horizons to livestock carbon balance research and give evidence that grazing systems sequester carbon emissions from cattle and in some cases are a carbon sink. Advisors: Galen E. Erickson and Andy Suyke

Advanced Instrumentation for Practical Applications of Terahertz Spectroscopy and Imaging

Dans le spectre électromagnétique, la bande des térahertz (THz) est située entre les microondes et l’infrarouge. Le système de spectroscopie térahertz dans le domaine du temps (THz-SDT) permet d’extraire directement le champ électrique multifréquentiel. Déjà, plusieurs applications avantageuses ont été trouvées pour l’imagerie et la spectroscopie THz, et ce dans divers domaines. Cependant, malgré le potentiel que recèle les THz, plusieurs défis doivent être relevés pour faciliter sa généralisation. Dans cette thèse, nous suggérons des solutions nouvelles à deux problèmes et nous présentons une implémentation d’un système d’imagerie THz 3D, connu sous le nom de tomographie assistée par ordinateur. Premièrement, la manipulation du faisceau THz est difficile. Afin de remédier à cela, nous explorons deux types de guides d’onde en mousse : la mousse de polystyrène et la mousse de soie. La mousse de polystyrène est utilisée comme gaine pour le guide d’onde THz à deux fils métalliques. Nous montrons que les pertes additionnelles dues à la gaine de mousse sont négligeables par rapport à l’avantage d’avoir une encapsulation robuste et hermétique du guide d’onde. Pour la mousse de soie, nous montrons que les pertes sont un ordre de grandeur inférieures à celles de la soie solide. La mousse de soie a l’avantage d’être biocompatible pour des applications biomédicales ou agroalimentaires. Deuxièmement, l’acquisition de l’impulsion THz prend beaucoup de temps. La composante la plus lente dans un système THz-SDT est la ligne à délai optique. Nous implémentons une ligne à délai rotative qui est capable de réduire significativement le temps d’acquisition total. De plus, nous présentons des applications nouvelles pour les THz. Ces applications étaient auparavant impossibles en raison, justement, du long temps d’acquisition. Spécifiquement,nous observons, en temps réel, les processus d’évaporation de liquides transparents, l’application et le séchage de la peinture aérosol opaque, ainsi que la détection et l’évaluation de l’épaisseur d’objets mobiles. Troisièmement, nous implémentons un système d’imagerie THz 3D de tomographie assistée par ordinateur. Le système THz-SDT permet d’imager sur plusieurs fréquences et d’extraire l’indice de réfraction complexe d’un échantillon. Cependant, lors de l’implémentation d’un système d’imagerie THz 3D de tomographie assistée par ordinateur, plusieurs défis s’imposent,le principal étant le long temps d’acquisition. Ici, nous présentons un début d’implémentation d’un tel système. Nous discutons de plusieurs problèmes et nous présentons des solutions pour certains.----------Abstract In the electromagnetic spectrum, the terahertz (THz) frequency band is located between the microwave and the infrared. The pulsed THz time-domain spectroscopy (THz-TDS) system allows direct access to the THz electric field and its multifrequency nature. Already, THz imaging and spectroscopy have been applied to many different fields. Despite all the interest and potential, there a still some hurdles impeding its generalized use. In this thesis, we suggest novel solutions to two issues and we present an implementation of a THz 3D Imaging modality known as computed tomography. First, the handling of the THz beam is difficult. To overcome this, we explore two kinds of foam waveguides : polystyrene foam and silk foam. We use the polystyrene foam as a cladding for the THz two-wire waveguide. We show that the additional losses are offset by the mechanically robust and hermetical foam encapsulation. As for the silk foam, we show that the losses are one order of magnitude lower than those of solid silk. Here, the silk foam has the advantage of being biocompatible for biomedical and agro-alimentary applications. Second, the acquisition of the THz pulse is time-consuming. The slowest component in a regular THz-TDS system is the linear optical delay line. We implement a fast rotary delay line that is able to significantly reduce the overall time acquisition. Additionally, we present novel applications for THz. These applications were not possible before, because of the long time acquisition. Specifically, we observe, in real time, the evaporation of transparent liquids, the spray painting process, as well as the detection and thickness evaluation of moving objects. Third, we implement a THz 3D computed tomography imaging system. The THz-TDS allows multifrequency imaging and direct extraction of the complex refractive index. However, when doing computed tomography imaging on a THz-TDS system, several challenges arise, the main one being the time acquisition. Here, we present an early implementation of such a system. We discuss several issues and we present solutions to some

Significant NASA inventions: Available for licensing in foreign countries

Abstracts are given of various NASA-owned inventions which are available for foreign licensing in the identified countries in accordance with the NASA Foreign Patent Licensing Regulations

Exploring photoprotection in natural ultraviolet filters

Ultraviolet radiation causes a number of deleterious effects on humans and other living organisms. As such, photoprotection is crucial, and whilst humans produce melanin as a natural defence mechanism, this is not usually sufficient. Therefore, alternative photoprotection is required and one way is through the use of sunscreens. The ultraviolet filters currently used within sunscreens have a number of associated drawbacks. As a result, alternative ultraviolet filters are needed and one approach is taking inspiration from nature. This thesis does exactly that as the molecules of interest are a family of natural ultraviolet filters, mycosporines and mycosporine-like amino acids. In this thesis, a bottom-up approach has been adopted to glean insight into the simplest system first and then increasing the complexity of the studied system from a photochemical and photophysical standpoint. In Chapter 2, the cyclohexenone building block of mycosporines was investigated as an extension of previous work. Experimental and computational results determined that the majority of population recovers back to the electronic ground state on ultrafast timescales. As a result, the cyclohexenone core is not as poor of an ultraviolet filter as previously thought. In Chapters 3 and 4, a number of mycosporine-like amino acids were explored spectroscopically and computationally. The results linked the ultrafast dynamics to their unrivalled long-term photostability, thus highlighting the efficiency of the photoprotective mechanism in these molecules. Finally, Chapter 5 took the investigations further by examining a crude extract from Palmaria palmata containing mycosporinelike amino acids in more viscous and restricted surface environments. It was found that the photoprotective mechanism was retained in these environments. Overall, this thesis demonstrates the efficient photon-to-heat conversion capabilities of mycosporine-like amino acids making them ideal candidates as ultraviolet filters. Furthermore, such results can guide the future experiments and chemical design of not only ultraviolet filters in sunscreens but in any field where photon-to-heat conversion is desirable

Significant NASA inventions available for licensing in foreign countries

Abstracts of various NASA-owned inventions which are available for foreign licensing in the identified countries are listed in accordance with the NASA Patent Licensing Regulations. Instructions for requested applicatons are explained

Development and application of UV-visible and mid-IR differential absorption spectroscopy techniques for pollutant trace gas monitoring

Spatial representativeness is an important quality criterion in trace gas monitoring, especially if measurements are intended for regulatory and model validation purposes. Open-path absorption spectroscopy techniques meet the representativeness requirement by providing concentrations averaged over atmospheric paths ranging from some hundred meters to some kilometers. This research concerns the characterization and application of a UV-visible differential optical absorption spectroscopy (DOAS) system, and the development and demonstration of a trace gas detection technique based on tunable, mid-infrared (mid-IR) quantum-cascade lasers (QCL). The spectral accuracy, stability and resolution of the DOAS spectrometer, and the efficiency of its PMT1-based light detection system were characterized and tested in laboratory and field conditions. Additional laboratory experiments included exploratory test of a photodiode array (PDA) as multichannel analyzer, and spectral analysis of the arc of high-pressure Xe lamps. PDA measurements of NO2 in the 360-530 nm range show an effective lower detectable fractional absorbance of 8·10-4 (1-sigma) for a 3-s integration time, overpassing the detection capabilities of the scanner/PMT system. DOAS measurements of SO2, NO2, and O3 were extensively validated through laboratory calibration and intercalibration, and field intercomparison with conventional point monitors and EPA2-certified DOAS systems, showing good agreement among the different instruments. A nitrous acid (HONO) generator was developed and used for characterizing the DOAS detection capability. Laboratory measurements indicate a lower detection limit (LDL) of ~0.2 ppm·m HONO (2-sigma) for a 30-min integration time. Concerning formaldehyde (HCHO), a field intercomparison with HPLC3-analyzed DNPH4 samples shows a non-aleatory, high degree of correlation (r2 = 97%) between the two techniques, but unexplained, significant deviation from the 1:1 line (which is nevertheless within the 85% confidence interval of the correlation curve). A mathematical method was developed for the estimation of detection limits through the analysis of sequential lamp spectra. LDL estimations with this method are in very good agreement with operational detection limits. Other data processing and concentration retrieval algorithms were developed and used for analyzing laboratory and field measurements (12 campaigns). The analysis and interpretation of observations in two of these field studies are reported in detail. The first study concerns the dynamics and photochemical production regime of HCHO in the Grenoble region, France. DOAS measurements at a suburban location of Grenoble allowed estimating the sources of formaldehyde, and served at validating the results of a mesoscale photochemical grid model. Measurement-derived emission and photochemical production ratios are in good agreement with literature values, the emission inventory, and model calculations. A large fraction (>80%) of the HCHO observed at the measurement location is photochemically produced, and its production is VOC-limited / NOx-saturated. This investigation demonstrates also that DOAS is a well-suited technique for model validation purposes. The second study concerns the emission of monocyclic aromatic hydrocarbons (MAH) from a wastewater treatment plant in Lausanne (Switzerland) using DOAS and GC5/FID6-analyzed grab samples. Combined analysis of the vertical wind speed and the MAH concentration time series suggest a quasi-diurnal cycle involving accumulation of fugitive emissions during the stagnant early morning hours followed by rapid upward convective dispersion from midday on. This study indicates that the wastewater treatment plant is a potentially significant source of MAH in the Lausanne area. Measurements carried out in a high altitude (~2500 m ASL7) Andean valley (Sogamoso Valley, Colombia) are also presented and interpreted. A combined analysis of meteorological and O3 measurements performed at ground level (including DOAS) and airborne (with a homemade tethered balloon), along with model calculations, provide evidence for mesoscale inflow to the Sogamoso Valley of clean air masses from the Colombian Eastern Savanna (~200 m ASL). This quasi-diurnal anabatic flow plays an important role in the ventilation of the Sogamoso valley, particularly during the dry season. Despite of its high selectivity and sensitivity, and good temporal resolution, the UV-visible DOAS technique is restricted to a limited number species that display highly structured electronic bands. The advent of the quantum-cascade laser (QCL) in 1994, and its rapid development thereafter, offers to open-path absorption spectroscopy a promising doorway to the mid-IR. Quantitive detection of O3 at ambient pressure with a 9.6 µm pulsed-operated, single-mode DFB8 QCL was demonstrated in laboratory conditions. QCL transmission spectra in the 1044-1050 cm-1 range were obtained by tuning the laser temperature. O3 column densities retrieved from the mid-IR spectra are in good agreement with simultaneous DOAS measurements but the detection limit attained (~25 ppm·m) is still too high for immediate test in open path conditions. Currently ongoing improvements on the QCL pulse acquisition system should allow achieving detection limits at the level of commercial DOAS systems (~2 ppm·m) in the very near future. These results demonstrate the applicability of the differential absorption method to QCL absorption spectroscopy at ambient pressure and encourage its use for open path detection. -------------------------------------------------- 1 PMT: PhotoMultiplier Tube 2 EPA: US Environmental Protection Agency 3 HPLC: High Performance Liquid Chromatography 4 DNPH: 2,4-DiNitroPhenylHydrazine 5 GC: Gas Chromatography 6 FID: Flame Ionization Detector 7 ASL: Above the Sea Level 8 DFB: Distributed FeedBac