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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 181 records · Page 10

Injection Seeded Laser for Formaldehyde Differential Fluorescence Lidar

We describe the design and development of an injection seeded Nd:YVO4 laser for use in a differential fluorescence lidar for measuring atmospheric formaldehyde profiles. A high repetition rate Q-switched laser is modified to accept injection seed input to spectrally narrow and tune the output. The third harmonic output is used to excite formaldehyde (HCHO) fluorescence when tuned to a HCHO absorption line. Spectral confirmation is made with the use of a photoacoustic cell and grating spectrometer.

formaldehyde (HCHO) fluorescence↗

Monolithic High Power Semiconductor Seed Lasers near 2.05 µm

We report on the development and demonstration of a compact 2-micron semiconductor seed laser for CO2 lidar instruments. Our monolithic high-power fiber-pigtailed semiconductor seed laser will greatly enhance the operability and applicability of IPDA (Integrated Path Differential Absorption) lidar systems for high spatial and temporal resolution CO2 airborne measurements as well as future Earth-orbiting CO2 measurement missions. The compact semiconductor transmitter has a suitably narrow linewidth (less than 100 kilohertz) and enables flexible tuning (greater than 150 gigahertz) over several CO2 absorption lines in the 2.05-micron band.The frequency agility and multi-format modulation capability of the proposed technology, its small size and compatibility with standard DFB (Distributed FeedBack) lasers at the telecom band paves the way for adoption of the attractive 2.05-micron band for CO2 profiling and measurements.

Semiconductor Laser↗

Persistence of a Potential Pathogen on a Plant Microbiome-Does Seed Sanitization Matter?

Microbial interactions on, in, and around the seeds can have profound effects on plant growth, development, and productivity. These interactions can be casual or intimate in nature, but ultimately they all contribute in varying degrees to an ever-evolving microbiome. Plant microbiomes have been investigated over decades and new data continue to reveal how microbiomes play an important role in the plant’s success. Many eubacteria and fungi have been found to have a symbiotic relationship with plants and other microorganisms. The source of the plant microbiome on adult plants is provided by the seed via vertical transmission to leaf, root, flowers or fruit, as well as the surrounding environment.

Anirudha R. Dixit↗

Effect of a Large Population of Seeded Alumina Inclusions on Crack Initiation and Small Crack Fatigue Crack Growth in Udimet 720 Nickel-Base Disk Superalloy

Crack initiation, crack coalescence and small crack growth behavior were monitored for over 400 seeded inclusions during interrupted low cycle fatigue testing conducted on the P/M Udimet 720 nickel disk alloy at 650°C. Two types of seeded alumina inclusions with average sizes of 54 μm and 122 μm were used in the study performed at varying loading conditions resulting in LCF lives ranging from 2,000 cycles to over 1,000,000 cycles. The fatigue behavior was sub-categorized into four groups. Visual maps detailing inclusion size/cycle history were developed. The effect of surface residual stresses on the fatigue life was also investigated.

Superalloys↗

Augmentation of Seed Film Technology With Probiotics in Support of Space Crop Production

This project set out to establish a method for introducing Plant Growth Promoting Microbes to seed film for use in a flight-based crop production system. The inoculation method, demonstrated in this paper, succeeded in this introduction while simultaneously avoiding disrupting the integrity of the seed film material. Future research should continue to explore the idea of growth production and crop protection via intentional introduction of an exophytic microbiome including the verification of effects of varying inoculum concentrations on mature plants. Positive effects are more likely to be noted when multiple organisms are introduced simultaneously. Additional benefit is likely to be seen on an experimental basis when crops are challenged via the introduction of both biotic and abiotic stressors.

Aubrie E Orourke↗

Researching Seeds: Films, Sanitation Methods, Microbiological Growth, Viability, and Selection for New Crops

A major factor in long-term human exploration of the solar system is crop growth in microgravity. Space crops can provide fresh, nutritious food to supplement diets for astronauts. Important factors impacting space plant growth and consumption are water delivery to root zone in microgravity, sanitation methods for microbiological safety, plant responses to light quality/spectrum, and identifying optimal edible plants suitable for growth on the International Space Station (ISS). Astronauts growing their own food on the ISS provides necessary data for crop production for long duration deep space missions. The seed film project can be used in Advanced Plant Habitat and Veggies that are currently being utilized on the ISS.

Plant Biology↗

A study of seeded rotating arcs.

Neutral carrier gas and slightly ionized plasma binary mixture model for nonhomogeneous seeding effects on rotating arc performance

ROTATING FLUID↗

The SEEDS Direct Imaging Survey for Planets and Scattered Dust Emission in Debris Disk Systems

Debris disks around young main-sequence stars often have gaps and cavities which for a long time have been interpreted as possibly being caused by planets. In recent years, several giant planet discoveries have been made in systems hosting disks of precisely this nature, further implying that interactions with planets could be a common cause of such disk structures. As part of the SEEDS high-contrast imaging survey, we are surveying a population of debris disk-hosting stars with gaps and cavities implied by their spectral energy distributions, in order to attempt to spatially resolve the disk as well as to detect any planets that may be responsible for the disk structure. Here we report on intermediate results from this survey. Five debris disks have been spatially resolved, and a number of faint point sources have been discovered, most of which have been tested for common proper motion, which in each case has excluded physical companionship with the target stars. From the detection limits of the 50 targets that have been observed, we find that beta Pic b-like planets (approximately 10M(sub jup) planets around G-A-type stars) near the gap edges are less frequent than 15-30%, implying that if giant planets are the dominant cause of these wide (27 AU on average) gaps, they are generally less massive than beta Pic b.

high-contrast imaging↗

Commercial Seed Selection and Effectiveness of Sanitization Methods in Preparation for Plant Growth Experiments on the International Space Station

A closed-loop food production system will be important to gain autonomy on long duration space missions. Crop growth experiments in the Veggie plant chamber aboard the International Space Station (ISS) are helping to identify methods and limitations of food production in space. Prior to flight, seeds are surface sterilized to reduce environmental and crew contamination risks.

crop selection↗