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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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This document provides guidance for retrofitting existing fluorescent troffers including the LED and associated control options available, the pro/cons and costs/benefits of each option, and agency specific requirements (where applicable).
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Building on the 3-year End-Use Load Profiles project to calibrate and validate the U.S. Department of Energy’s ResStock™ and ComStock™ models, this work produces national datasets that enable cities, states, utilities, and other stakeholders to answer a broad range of questions regarding their commercial building stock.
Developing systems that can efficiently capture photon energy and convert this energy into fuels and chemicals requires understanding how to assemble molecular components with diverse functions into complete systems possessing selectivity and efficiency in directing charge carriers to catalytic reactions. There are many challenges to achieving this goal. One promising approach is the development of hybrid systems that combine semiconductor nanocrystals (NCs) for light capture and enzymes as efficient catalysts. Such biohybrid systems capitalize on the tunable electronic and optical properties of NCs while leveraging the unmatched specificity and efficiency of enzymes in catalyzing chemical reactions, thereby offering opportunities to surpass the limitations of each component alone. Here, we focus on recent progress in developing a biohybrid system that combines CdS NCs for photon capture with the enzyme nitrogenase to accomplish light-driven dinitrogen (N 2 ) reduction to ammonia (NH 3 ). Integrating light-harvesting materials with biological catalysts requires a deep understanding of NC properties, protein stability, and electron transfer (ET), making it an inherently multidisciplinary problem. The reduction of N 2 to NH 3 is a challenging reaction, with a high demand in both agriculture and industrial chemical production. This reaction is intrinsically energy intensive, due to the need to activate the N≡N triple bond. The current standard industrial approach to N 2 reduction, the Haber−Bosch reaction, obtains the necessary energy input from fossil fuels, whereas biological systems capable of N 2 reduction utilize the hydrolysis of ATP as their energy source. Replacing these costly, energy-intensive inputs with renewable light energy represents a critical step toward sustainable NH 3 production. Recent progress has demonstrated that semiconductor CdS NCs can be coupled to the catalytic component of nitrogenase, the MoFe protein, to form a biohybrid CdS NC:MoFe protein complex, enabling light-driven N 2 reduction rather than energy input from fossil fuels or ATP. This illustrates how inorganic NCs can functionally replace the natural Fe protein partner, yielding a biohybrid catalyst that enables controlled electron delivery and provides not only light-driven NH 3 production but also new approaches for probing enzyme catalytic function. The CdS NC:MoFe protein biohybrid system enables light-initiated electron delivery at ambient temperature, as well as temperatures below freezing, allowing for stabilization and spectroscopic characterization of key reaction intermediates. These findings highlight how photochemical biohybrids can serve as both functional catalysts and mechanistic probes. Beyond studies of the nitrogenase mechanism, studies of the CdS NC:MoFe system reveal how variables such as NC size, electrostatic binding interactions, and sacrificial electron donors (SEDs) govern complex stability, charge transfer efficiency, and catalytic performance. In addition, studies of nitrogenase and the high activation barrier for N 2 reduction are enabling investigations of new and interesting questions regarding the properties and limitations of NC biocatalysis. In this Account, we describe the key features of CdS NC:MoFe protein biohybrids and the parameters for optimal light-driven N 2 reduction, and how controlling ET with light illuminates the path to new insights into the nitrogenase mechanism.
Emory University and Georgia Institute of Technology (Georgia Tech) partnered to create the Charlie and Harriet Schaffer Cognitive Empowerment Program (CEP) facility in northeast Atlanta. Together with the funders they are building a program to help individuals experiencing mild cognitive impairment (MCI) to maintain their physical and cognitive health, and independence as long as possible. In addition to applying effective strategies and therapies, the two research groups are investigating the responses of the MCI members to treatments that involve acoustical conditions, exercise and movement, and lighting changes that may support retention or relearning of skills. Care partners and family members receive support and instruction to improve home and work life, promoting joy, purpose, and wellness in the family groups. The lighting system uses tunable-white LEDs, employing luminaires with both warm and cool-color emitters that can be dimmed separately to produce any white correlated color temperature (CCT) between 2700 K and 6500 K. All luminaires were dimmable to achieve subdued or lively surroundings for different treatments, time-of-day, and mood. A central networked digital control system was employed to allow tuning of multiple spaces together (for example, bright, cool morning light could be programmed for extra stimulation, or lighting in all spaces at the end of the day could be reduced in both light output and CCT to promote relaxation and not interfere with the melatonin cycle of occupants). Almost all spaces were equipped with individual room control of dimming and color temperature with touch screens to allow users to tune the lighting as desired, but each room’s controls could also be specially programmed through the server in case the research staff were investigating lighting settings on learning, for example. The server incorporates a timeclock, and it is able to send signals to switch off all lighting after occupancy hours, or enable occupancy sensors to control the lighting. The bulk of the construction work was completed in January 2020. It was clear from an initial walk-through that although the lighting system produced the expected high light level with low-glare qualities of light, that there were issues and inconsistencies to be resolved. These were noted in an initial punchlist visit and expected to be resolved when the tech representatives from the agency visited with the electrical contractor in the following few weeks. What followed was 2.5 years of identifying unexpected lighting performance in terms of light output, color, scheduling, and occupancy. This report documents the issues encountered in the effort to get the lighting and controls systems to operate as intended. It concludes with guidance for design professionals and manufacturers to help avoid problematic complexity in future projects.
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Traffic warning light for school crossing, construction zones, and other hazardous areas activated by remote control. Apparatus consists of small radio transmitter, pole-mounted strobe light with attached power supply and radio receiver.
Solution-processable semiconductors based on small molecules, polymers or halide perovskites combine sustainable manufacturing with exceptional optoelectronic properties that can be chemically tailored to achieve flexible and highly efficient optoelectronic and photonic devices. A new exciting research direction is the study of the influence of chirality on light-matter interactions in these soft materials and its exploitation for the simultaneous control of charge, spin and light. In this Viewpoint, researchers working on different types of chiral semiconductors discuss the most interesting directions in this rapidly expanding field.
Phytochromes are red-light photoreceptors that were first characterized in plants, with homologs in photosynthetic and non-photosynthetic bacteria known as bacteriophytochromes (BphPs). Upon absorption of light, BphPs interconvert between two states denoted Pr and Pfr with distinct absorption spectra in the red and far-red. They have recently been engineered as enzymatic photoswitches for fluorescent-marker applications in non-invasive tissue imaging of mammals. This article presents cryo- and room-temperature crystal structures of the unusual phytochrome from the non-photosynthetic myxobacterium Stigmatella aurantiaca (SaBphP1) and reveals its role in the fruiting-body formation of this photomorphogenic bacterium. SaBphP1 lacks a conserved histidine (His) in the chromophore-binding domain that stabilizes the Pr state in the classical BphPs. Instead it contains a threonine (Thr), a feature that is restricted to several myxobacterial phytochromes and is not evolutionarily understood. SaBphP1 structures of the chromophore binding domain (CBD) and the complete photosensory core module (PCM) in wild-type and Thr-to-His mutant forms reveal details of the molecular mechanism of the Pr/Pfr transition associated with the physiological response of this myxobacterium to red light. Specifically, key structural differences in the CBD and PCM between the wild-type and the Thr-to-His mutant involve essential chromophore contacts with proximal amino acids, and point to how the photosignal is transduced through the rest of the protein, impacting the essential enzymatic activity in the photomorphogenic response of this myxobacterium.
In strong-field ionization of molecules, intense light pulses are thought to have a negligible direct influence on atomic nuclei. Molecular dissociation is thus expected to be determined by the geometrical configuration of the molecular ion at the ionization instant. Contrary to this picture, we observe a counterintuitive electron-proton angular correlation and the formation of proton vortices following strong-field ionization of H 2 molecules by bicircularly polarized two-color laser fields. We explain this phenomenon by the pathway interference and localization of the residual H 2 + electron in different angular-momentum states formed in the tail of the driving laser pulse. We validate this interpretation by combining a quantum-mechanical numerical simulation of the field-driven coupled electronic-nuclear dynamics and a semiclassical-trajectory model for the phase accumulation of the laser-driven electronic-nuclear wave packet. Our joint experimental and theoretical study reveals a general picture of vortex electron localization which can be used for controlling molecular-bond breaking with circularly polarized laser fields.
This document provides a framework for measurement and verification (M&V) of energy savings, performance, and user satisfaction from lighting retrofit projects involving occupancy-sensor-based, daylighting, and/or other types of automatic lighting. It was developed to provide site owners, contractors, and other involved organizations with the essential elements of a robust M&V plan for retrofit projects and to assist in developing specific project M&V plans.
Metastable phases present a promising route to expand the functionality of complex materials. Of particular interest are light-induced metastable phases that are inaccessible under equilibrium conditions, as they often host new, emergent properties switchable on ultrafast timescales. However, the processes governing the trajectories to such hidden phases remain largely unexplored. Here, using time- and angle-resolved photoemission spectroscopy, we investigate the ultrafast dynamics of the formation of a hidden quantum state in the layered dichalcogenide 1T-TaS 2 upon photoexcitation. Our results reveal the nonthermal character of the transition governed by a collective charge-density-wave excitation. Using a double-pulse excitation of the structural mode, we show vibrational coherent control of the phase-transition efficiency. Our demonstration of exceptional control, switching speed, and stability of the hidden state are key for device applications at the nexus of electronics and photonics.
Frontal ring-opening metathesis polymerization (FROMP) is a promising energy-efficient approach to fabricate polymeric materials. Recent advances have demonstrated FROMP for diverse applications, including additive manufacturing, composites, and foams. However, the characteristic properties of the front are currently controlled primarily by varying the resin composition or the environmental conditions. In this work we present an approach to control FROMP of dicyclopentadiene (DCPD) using photochemical methods. A photobase generator is used to inhibit FROMP of DCPD with UV light while a photosensitizer and co-initiator are used to accelerate FROMP with blue light, enabling orthogonal active photocontrol of front velocity. In addition, photoinhibition-enabled lithographic patterning of frontal polymerizations is demonstrated. Frontal polymerizations are spatially controlled, redirected, and even split into diverging fronts. This work establishes a foundation for advanced control of frontal polymerizations, enabling innovation in traditional and additive manufacturing, as well as emerging processes like morphogenic manufacturing.
This guide provides federal facility managers with an overview of the energy savings potential of wireless lighting occupancy sensors for various room types, cost considerations, key steps to successful installation of wireless sensors, pros and cons of various technology options, light source considerations, and codes and standards.
Cysteine-based Michael addition is a widely employed strategy for covalent conjugation of proteins, peptides, and drugs. The covalent reaction is irreversible in most cases, leading to a lack of control over the process. Utilizing spectroscopic analyses along with X-ray crystallographic studies, we demonstrate Michael addition of an engineered cysteine residue in human Cellular Retinol Binding Protein II (hCRBPII) with a coumarin analog that creates a non-fluorescent complex. UV-illumination reverses the conjugation, yielding a fluorescent species, presumably through a retro-Michael process. Furthermore, this series of events can be repeated between a bound and non-bound form of the cysteine reversibly, resulting in the ON–OFF control of fluorescence. The details of the mechanism of photoswitching was illuminated by recapitulation of the process in light irradiated single crystals, confirming the mechanism at atomic resolution.
We report the results of measurements of the threshold of Freedericksz transition in a nematic liquid crystal doped by Methyl-red. We show that in case of dc field the threshold voltage can decrease or increase depending on the light dose, due to the light-induced desorption and adsorption of charge complexes from and on the irradiated surface, that has been recently demonstrated. This effect has the potential to be exploited in optical devices such as liquid crystal microlenses and spatial light modulators.
LONG HYPOCOTYL5 (HY5) and STF1 (Soybean TGACG-motif binding Factor 1) are two related bZIP transcription factors that play a positive role in photomorphogenesis and hormonal signaling. In this study, we compared full length STF1 and truncated STF1 overexpression lines and found that the C-terminal 133 amino acids (194–306) possess all the HY5-like function in Arabidopsis. The STF1-DC1 mutant (1–306), with a 20 amino acid deletion at the carboxy terminus, failed to complement the hy5 mutant phenotype, which suggests an intact C-terminus is required for STF1 function. To understand the role of the C-terminal domain in photomorphogenesis we used a yeast two-hybrid screen to isolate proteins that bind to the STF1 C-terminus. We isolated three soybean cDNAs encoding the zinc-finger proteins GmSTO, GmSTH, and GmSTH2, which interact with STF1. These proteins belong to a family of B-box zinc finger proteins that include Arabidopsis SALT TOLERANCE (STO) and STO HOMOLOG (STH) and STH2, which play a role in light-dependent development and gene expression. The C-terminal 63 amino acids of STF1, containing a leucine zipper and the two N-terminal B-boxes, contains the domain involved in interactions between STF1 and GmSTO. In addition, we identified an interaction between soybean COP1 (GmCOP1) and GmSTO and GmSTH, as well as STF1, which strongly suggests the presence of a similar regulatory circuit for light signaling in soybean as in Arabidopsis. This study shows that photomorphogenic control requires complex molecular interactions among several different classes of transcription factors such as bZIP, B-box factors, and COP1, a ubiquitin ligase. - Highlights: • STF1 interact with GmSTO, GmSTH and GmSTH2. • The bZIP transcription factor STF1 requires an intact C-terminal domain for STF1 function. • STF1 and GmSTO are nuclear proteins.
ZnWO{sub 4} nanowires array was prepared on the titanium substrate by a facile hydrothermal synthesis, in which the average length of ZnWO{sub 4} nanowires is about 2um and the diameter of individual ZnWO{sub 4} nanowire ranges from 50 to 70 nm. The bipolar resistive switching effect of ZnWO{sub 4} nanowires array was observed. Moreover, the performance of the resistive switching device is greatly improved under white light irradiation compared with that in the dark.