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DOE OSTI2024

The effects of thickness, polarization, and strain on vibrational modes of 2D Fe 3 GeTe 2

In this study, we investigated the effects of thickness, light polarization, and strain on the Raman spectra of two-dimensional (2D) Fe 3 GeTe 2 (FGT) crystals synthesized via chemical vapor transport. The crystals are thoroughly characterized using a combination of microscopic, diffraction, and spectroscopic techniques. Particularly, a systematic angle-resolved polarized Raman spectroscopy study reveals a clear polarization dependence of the Raman intensity in both parallel and crossed polarization directions, with the $A$$^{1}_{g}$ mode completely disappearing in the crossed polarization direction. The angle-dependent intensity of both the $A$$^{1}_{g}$ and $E$$^{2}_{2g}$ modes in parallel polarization and the intensity of the $E$$^{2}_{2g}$ mode in the crossed polarization remain constant at all angles. These findings align with predictions from Raman tensor analysis, providing compelling evidence for the unambiguous assignment of the $A$$^{1}_{g}$ and $E$$^{2}_{2g}$ modes to specific peaks observed in the Raman spectrum of FGT, resolving existing confusion in the literature regarding their assignment. Furthermore, we examine the effect of strain on the Raman spectrum of 2D FGT in-situ using a bending device. Our study, conducted on a monolayer to few-layer 2D FGT deposited onto polyethylene terephthalate and subjected to outward (inward), i.e., tensile (compressive) bending, demonstrates appreciable downshifting (upshifting) of the Raman peak position of both $A$$^{1}_{g}$ and $E$$^{2}_{2g}$ modes. Furthermore, these findings are particularly significant given that strain engineering represents an effective approach to modulate the magnetic properties of FGT and other 2D magnetic materials.

2D materials↗

DOE OSTI2025

Boron isotopic analysis in bulk silicate materials using the Neoma MS/MS MC-ICP-MS

Boron (B) isotopes are a valuable tracer with applications ranging from geological, environmental, and nuclear studies because B isotopic fractionation is highly sensitive to chemical processes yielding distinct isotopic trends in natural and anthropogenic systems. Despite this wide applicability, there remain relatively few measurements on well-described reference materials and in some cases, poor agreement between various methods. We report a method for boron isotope ratio measurement in solution on the Neoma MS/MS MC-ICP-MS specifically targeting bulk silicates. We evaluate the performance of the method and instrument as it relates to the measurement of the absolute boron isotope ratio ( 10 B/ 11 B). The results indicate that the method produces data in agreement with literature values and that the sample–standard bracketing technique is appropriate for the Neoma MS/MS MC-ICP-MS which has been in use for decades on previous generation instruments. Careful tuning of the MS/MS lenses is required to obtain precision comparable to non MS/MS equipped MC-ICP-MS. With careful tuning, internal and external precisions of ∼0.3‰ were achieved. However, when the MS/MS is not properly tuned external precisions exceed 3‰. Nevertheless, our results for IAEA B-6, BCR-2, BHVO-2 and W-2a reference materials overlap the 1σ range of previously reported 10 B/ 11 B. Data are reported for total boron quantities down to a few tens of nanograms. Our procedure yielded blanks as low as 3 ng but up to 29 ng, making blank corrections important for small samples sizes in the few 10s of nanogram range. We report B isotope ratios for AGV-2G, SL-1G, GSC-2G, GSD-2G, GSE-2G, RLS-132, RLS-140, NKT-1G, and T1-G glass reference materials that have not been previously reported in the literature.

Scott, Sean R. [Pacific Northwest National Laborat↗

DOE OSTI2026

Data for Optimization of Pre-Commercial Enzymes Dosage for a Potential Lignocellulosic Biorefinery

Lignocellulolytic enzymes remain one of the primary cost constraints in second-generation (2G) ethanol biorefineries. Achieving efficient hydrolysis of structural carbohydrates with minimal enzyme dosage, maintaining slurry fermentability for industrially relevant ethanol titers, and maximizing ethanol yield per ton of biomass are among the major challenges in 2G processes. In this study, we optimized the dosages of pre-commercial cellulase (NS22257) and hemicellulase (NS22244) on pilot-scale, hydrothermally pretreated lignocellulosic substrates. Enzyme dosages were evaluated at three levels: 20 mg of cellulase with 7.25 mg of hemicellulase (ED-1), 40 mg with 14.5 mg (ED-2), and 60 mg with 21.75 mg (ED-3). As expected, the highest sugar yields were obtained with ED-3; however, for sweet sorghum, oilcane, and miscanthus, sugar yields from ED-2 and ED-3 were not significantly different (p < 0.05). For example, sweet sorghum produced 123.78 ± 1.54 g L−1 and 125.76 ± 0.46 g L−1 of total sugars (glucose and xylose) with ED-2 and ED-3, respectively. Although energycane exhibited a statistically significant difference between ED-2 and ED-3, the incremental gain with ED-3 was modest, increasing sugar release by only 9.02 g L−1 relative to ED-2. Importantly, ED-1 resulted in sugar yields of 88.88 ± 3.64 to 106.86 ± 1.21 g L−1, sufficient to achieve ethanol titers ≥40 g L−1, the threshold required for industrial relevance. A semi-integrated bioprocess validated this outcome, producing 42.09 ± 2.38 g L−1 ethanol and an estimated yield of 213.38 L of ethanol per dry ton of pretreated biomass, requiring only 20.83 L of cellulase and 6.25 L of hemicellulase per ton. Remarkably, these enzyme dosages were approximately tenfold lower than those reported in prior studies.

Energycane↗

NASA NTRS1972

A performance application study of a jet-flap helicopter rotor

A performance study was made of the application of a jet-flap to a reaction-drive rotor for a heavy-lift helicopter mission and for a high-speed-helicopter maneuverability (200 knots, 2g) mission. The results of the study are as follows: As a result of the increase in maximum airfoil lift coefficient achieved by the jet-flap, rotor solidity is reduced with the jet-flap to approximately 59% of a nonjet-flap rotor. As a result of the saving in rotor solidity, and hence in rotor weight, the jet-flap configuration had a 21% higher productivity than a nonjet-flap configuration. Of the three propulsion systems studied utilizing a jet-flap (hot cycle, warm cycle, cold cycle) the hot cycle gave the largest increase in productivity. The 200 knot 2g mission is performed best with a warm cycle propulsion system. The jet-flap permits designing for a rotor blade loading coefficient C sub T/sigma = .170 at 2g without encountering blade stall. The jet-flap rotor permits a 200 knot 2g maneuver without suffering the penalty of an unreasonable rotor solidity that would be required by a nonjet-flap rotor.

Sullivan, R. J.↗

NASA NTRS2000

Effects of Hypergravity and Adrenalectomy on Total Body Bone Mineral Content in Male Rats

The effects of 14 days of increased gravitational load, and the absence of adrenal stress hormones on total body bone mineral content (BMC) were examined in male Sprague-Dawley rats. Centrifugation at 2 Gs (2G) was used to increase the gravitational load, and bilateral adrenalectomy (ADX) was used to eliminate the production of adrenal stress hormones. Stationary groups at 1 G (1G) and sham operated (SHAM) animals served as controls. Thirty rats (n=6 or 8) made up the four experimental groups (1G SHAM, 1G ADX, 2G SHAM and 2G ADX). BMC was assessed by dual energy X-ray absorptiometry (DXA) and activity was determined through biotelemetry. Body mass and food intake were also measured. Multi-factorial analysis of variance (MANCOVA) and Newman Keuls post hoc tests were used to analyze significant effects (p less than 0.05) for the primary variables. Results indicated that BMC decreased significantly with increased G for both the SHAM and ADX groups. The BMC for the 1 G ADX group was also significantly lower than the 1G SHAM group, however the 2G SHAM and ADX groups were not significantly different. There was a significant decrease in body mass with increased G and there was no ADX effect on body mass. When BMC was normalized for body mass changes, there were no significant group differences. Activity level decreased with body mass, and food intake data showed there was significant hypophagia during the first few days of centrifugation. These results suggest that the decrease in total body BMC seen with hypergravity may be based to a large extent on the differences in body mass induced by the 2 G load.

Girten, Beverly↗

NASA NTRS1999

Absence of Change in Total Daily Energy Expenditure (EE(sub TD)) in Young and Mature Rats During 14 Days of Hypergravity

Effect of age on the response of EE(sub TD) to an increase in gravity was assessed in young (Y; 1.5 month old) and mature (M; 8 month old) Sprague-Dawley rats. Rats were implanted with transmitters to monitor activity, and metabolism was determined by the double labeled water technique. Daily food intake was measured. For each age, rats (n=8 per treatment) were exposed to centrifugation at 2G, or remained at 1G. There was a difference in EE(sub TD) between age groups, 182 plus or minus 11 and 143 plus or minus 5 kcal/kg/day in Y and M, respectively. This difference was attributed in part to a lower activity level in M animals, 48% of Y rats. After day 6 there was no effect on EE(sub TD) of exposure to 2G, or on food intake per 100g BW. Prior studies show a 20% increase in resting EE with hypergravity. In our study the level of activity was reduced to 41% of 1G in both age groups during 2G. For Y at 1G resting EE accounted for 78% of the EE(sub TD) and activity 22%, while at 2G resting EE was 96% of EE(sub TD) and activity 4%. M rats had similar changes. Independent of age, with exposure to hypergravity EE(sub TD) is maintained by behavioral changes.

Wade, C. E.↗

DOE OSTI2018

Synthesis of Self-Assembled rGO-Co{sub 3}O{sub 4} Nanoparticles in Nanorods Structure for Supercapacitor Application

A simple hydrothermal process was used to design self-assembled Co{sub 3}O{sub 4} nanoparticles in nanorod structure in the presence of graphene oxide as a template. The as-prepared Co{sub 3}O{sub 4} sample in a loose powder form was calcined at 450 °C to get the well-crystalline phase of the same compound. The obtained Co{sub 3}O{sub 4} powder sample was characterized by using the powder XRD and SEM. The XRD pattern shows totally nine distinct reflection peaks of (111), (220), (311), (222), (400), (422), (511), (440), and (533) planes. The most intense peaks were chosen to evaluate the structural parameters. The lattice parameters (a), volume (V), and density (ρ) of the samples are 8.09 Å, 529.47 Å{sup 3}, 6.06 g/cc, which are comparable to the value of lattice parameter (a = 8.056 Å), volume (V = 528.30 Å{sup 3}), and density (ρ = 6.055 gm/cc) for bulk Co{sub 3}O{sub 4}. The average size of the Co{sub 3}O{sub 4} nanoparticles is 14 nm which is smaller than the SEM size of 50 nm corresponding to the agglomeration of tiny particles. Further, the formation of Co{sub 3}O{sub 4} nanoparticles were also confirmed by obtaining the band at 569, 1334,1337, 1566, and 3397 cm{sup −1} in FTIR spectrum. Totally five characteristics peaks from Co{sub 3}O{sub 4} at 182.57, 456.49, 505.84, 605.80, and 618.02 cm{sup −1} and peaks from GO-Co{sub 3}O{sub 4} at 182.57, 483.44, 505.84, 605.80, and 618.02 cm{sup −1} corresponding to F{sub 2g}, E{sub g}, F{sub 2g}, F{sub 2g,} and A{sub g} modes of the crystalline Co{sub 3}O{sub 4}, respectively, in the Raman spectra. In the case of GO-Co{sub 3}O{sub 4} composite, low-intensity peaks of D and G bands are observed. The specific capacitance in rGO-Co{sub 3}O{sub 4} nanocomposite is about 65.15 Fg{sup −1}.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2026

Deacetylation and Mechanical Refining Pathway for the Bioconversion of Sugarcane Bagasse

Advancing lignocellulose biorefining is imperative for the deployment of cellulosic (2G) biofuels. This work investigates the tailoring of the alkaline deacetylation and mechanical refining (DMR) pathway for the bioconversion of sugarcane bagasse. Experiments are conducted at laboratory and pilot scales, varying the pretreatment conditions (70–92 °C; 48–100 g NaOH /kg) and the mechanical refining technologies (PFI and disk refining). The pretreatments selectively solubilize acetyl groups (> 86%) and lignin (10–63%) while mostly preserving structural carbohydrates in the solid phase. Enzymatic hydrolysis generates hydrolysates of clean sugars (glucose and xylose), with sugar yields increasing up to 81% for glucose and 89% for xylose in response to delignification and mechanical refining. Biochemical methane potential assays reveal specific methane productions of up to 568 NmL CH₄ gVS⁻¹ for alkaline liquor monodigestion and 344 NmL CH₄ gVS⁻¹ for co-digestion with sugarcane vinasse from the conventional (1G) sugarcane ethanol, indicating a strong potential for bioenergy recovery from this process stream. Synergies are identified in integrating 1G ethanol, 2G DMR processing of bagasse, and anaerobic co-digestion of 1G vinasse and 2G DMR alkaline liquor. This technology enables sugarcane biorefineries to enhance the co-production of ethanol, methane, and concentrated streams of CO 2 .

09 BIOMASS FUELS↗

DOE OSTI2018

Two-step synthesis of a novel red-emitting Ba2ZrF8:Mn4+ phosphor for warm white light-emitting diodes

Highlights: • A novel red-emitting Ba{sub 2}ZrF{sub 8}:Mn{sup 4+} was prepared by two-step method at low temperature. • The phosphor shows an intense red emission under 460 nm excitation matching well with blue LED chip. • The energy transfer between Mn{sup 4+} was confirmed to be electric dipole-quadrupole interaction. - Abstract: A novel red-emitting Ba{sub 2}ZrF{sub 8}: Mn{sup 4+} phosphor was prepared by two-step method at low temperature, where critical precursor K{sub 2}MnF{sub 6} was prepared first by the reduction of KMnO{sub 4} using H{sub 2}O2 as reducer. The crystal structure and morphology of the phosphor was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), showing single phase product. Luminescent properties of the phosphor were investigated by photoluminescence spectroscopy (PL) and decay curves. The molar ratio of KMnO{sub 4}: KHF{sub 2} was confirmed to play the key role in improving the luminous efficiency. More importantly, the phosphor exhibits a broadband excitation from 300 to 520 nm due to {sup 4}A{sub 2g}→{sup 4}T{sub 1g} and {sup 4}A{sub 2g}→{sup 4}T{sub 2g} transition of Mn{sup 4+}, matching well with blue LED chips. Under 465 nm excitation, intense red emission at around 630 nm with high color purity is achieved, suggesting the red-emitting phosphor has great potential for white light-emitting diodes (wLEDs).

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2017

Localized-itinerant dichotomy and unconventional magnetism in SrRu2O6

Electron correlations tend to generate local magnetic moments that usually order if the lattices are not too frustrated. The hexagonal compound SrRu$_2$O$_6$ has a relatively high N{\'e}el temperature but small local moments, which seem to be at odds with the nominal valence of Ru$^{5+}$ in the $t_{2g}^3$ configuration. Here, we investigate the electronic and magnetic properties of SrRu$_2$O$_6$ using density functional theory (DFT) combined with dynamical mean field theory (DMFT). We find that the strong hybridization between Ru $d$ and O $p$ states results in a Ru valence that is closer to $+4$, leading to the small ordered moment, consistent with a DFT prediction. While the agreement with DFT might indicate that SrRu$_2$O$_6$ is in the weak coupling regime, our DMFT studies provide evidence from the mass enhancement and local moment formation that indicate correlation effects play a significant role. The local moment per Ru site is about a factor 2 larger than the ordered moment at low temperatures and remains finite in the whole temperature range investigated. Our theoretical N{\'e}el temperature $\sim 700$~K is in reasonable agreement with experimental observations. Due to a small lattice distortion, the degenerate $t_{2g}$ manifold is split and the quasiparticle weight is renormalized significantly in the $a_{1g}$ state, while correlation effects in $e_g'$ states are about a factor of 2--3 weaker. SrRu$_2$O$_6$ is a unique system in which localized and itinerant electrons coexist with the proximity to an orbitally-selective Mott transition within the $t_{2g}$ sector.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Intense deep-red zero phonon line emission of Mn 4+ in double perovskite La 4 Ti 3 O 12

Phosphors that emit in the deep-red spectral region are critical for plant cultivation light-emitting diodes. In this work, ultrabroadband deep-red luminescence of Mn 4+ in La 4 Ti 3 O 12 was studied, which showed intense zero phonon line emission. The double-perovskite structural La 4 Ti 3 O 12 simultaneously contains two Ti 4+ sites forming slightly- and highly-distorted TiO 6 octahedra, respectively. The influence of octahedral distortion on the Mn 4+ emission energy in the two distinct Ti 4+ sites was studied both experimentally and theoretically. The spectral measurements indicated that Mn 4+ in La 4 Ti 3 O 12 showed intense zero phonon line emission (ZPL) at deep-red 710–740 nm under excitation of 400 nm charging the O 2- → Mn 4+ charge transfer transition. The splitting of the ZPL of the Mn 4+ 2 E g → 4 A 2g transition as well as the intensity of ZPL relative to the vibronic phonon sideband emissions were found to be greatly influenced by the degree of octahedral distortion. The crystal-field strength and Racah parameters of Mn4+ in each Ti4+ site were also estimated. The Mn 4+ 2 E g → 4 A 2g luminescence exhibited severe thermal quenching, which was explained by the low-lying 4 T 2g level and charge-transfer state.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2018

India Alternative Fuel Infrastructure: The Potential for Second-generation Biofuel Technology

This report is an attempt at understanding the potential for the adoption of a second-generation biofuel technology in India. It starts by laying out the state of play in 1G technology at a global level as well as in India. It then goes on to talk about the limitations of the 1G technology in India in meeting the GOI’s blending mandate. It then proceeds to lay out what 2G technology entails, what the cost numbers are for this technology and the possibility of deploying it on a commercial scale in India. It talks about some of the added advantages of 2G technology – primarily that it addresses the problem of pollution from stubble burning. It ends by identifying the limitations of 2G technology both at the global level and in India and talks about policies (currently in use and recommendations) that both encourage and impede its adoption.

09 BIOMASS FUELS↗

DOE OSTI2022

Front-End Engineering Design for Piperazine with the Advanced Stripper

This Department of Energy (DOE) funded project was executed with the goal of preparing a Front-End Engineering Design (FEED) for the capture and compression of 90% of the CO2 that would normally be emitted from an existing natural gas combined cycle (NGCC) plant. The FEED focused on the application of the piperazine advanced stripper (PZAS) process at Mustang Station of the Golden Spread Electric Cooperative (GSEC), which consists of two gas turbines with common heat recovery steam generator (HRSG). The University of Texas at Austin (UT) served as the prime contractor, and subcontracted AECOM Technical Services and Trimeric Corporation to support FEED development. This project team has worked together to advance PZAS for more than a decade. ExxonMobil, Chevron, and Total provided project co-funding. The objectives of this work included: 1. To advance engineering design such that a comprehensive estimate for the total installed cost of a full-scale PZAS CO2 Capture Plant with CO2 compression can be developed on an existing NGCC power plant. a. These detailed costs can also be used to qualify PZAS and other related second generation (2G) amine scrubbing processes for use on cogeneration facilities in refineries and chemical plants that use gas turbines with HRSGs to produce steam. b. These detailed costs will help qualify 2G amine scrubbing for use on NGCC power plants and establish a more accurate baseline cost to be used as a target by other capture technologies. 2. To provide cost details to be used in the economic optimization of the process features of PZAS and other 2G amine scrubbing processes. 3. To provide DOE with a more detailed understanding of carbon capture costs in a commercial application, enabling DOE to better design its R&D program to improve the economics for carbon capture. 4. To provide the host site and cost share partners with the information necessary to determine whether a commercial project to capture and use CO2 for enhanced oil recovery (EOR) or for sequestration can be justified (when accounting for the 45Q tax credit). A key component of the FEED is the estimated total installed cost, which provides a basis for the likely capital investment necessary to implement the PZAS carbon capture process at this location and scale. In combination with the included economic analysis, which accounts for potential revenue from the produced CO2, potential avenues to profitability are explored. The major findings of the FEED are as follows: The Mustang Station PZAS CO2 Capture Plant estimated total project cost of $698 MM of which $384 MM was direct costs. The annual operating costs were $32.6 MM. The total investment for a PZAS facility at Mustang Station is $725 MM. This estimate includes owner’s cost of $25 million and a contingency of $110 MM. • The study estimated the CO2 capture plant at Mustang Station would generate CO2 at $110/tonne for EOR, assuming a 12% IRR (internal rate of return) and an 85% capacity factor. For CO2 storage, the same case would achieve a 12% IRR at about $114/tonne. At a capacity factor of 52%, the storage and EOR cases would break even when carbon is priced ~$150/tonne. The economic analysis determined that the capacity factor and utility pricing, among other variable factors, had a significant effect on the economics and will need additional studied. • The energy penalty of the PZAS plant would be about 46 MW in connected power and 35 MW in operating load. The natural gas requirement (for the Gas Boiler package) would be about 354 MMBTU/hr. • The FEED revealed no major risks in process maturity. However, some areas were outlined for further engineering during detailed design, which included the Gas Boiler system, general arrangement and site layout, air coolers, schedule development, and optimization of the process for higher CO2 removal. • If PZAS were to be implemented at another host site, additional opportunities for cost reduction for would include cost reduction through use of cooling water and steam extraction.

03 NATURAL GAS↗

DOE OSTI2025

Angle-resolved polarized Raman spectroscopy study of phosphorene nanoribbons

We present a systematic angle-resolved polarized Raman spectroscopy (ARPRS) study of black phosphorus (BP) nanostructures formed via electrochemical sodium- and lithium-ion intercalation. Sodium intercalation leads to bundles of densely packed, highly uniform phosphorene nanoribbons (PNRs) separated by parallel amorphous channels, whereas lithium intercalation results in shorter, irregular nanoribbon-like segments with lower aspect ratios. In both cases, six additional Raman peaks (P1–P6) appear alongside the three primary Raman-active modes of BP (A$^{1}_{g}$, B 2g , and A$^{2}_{g}$). These peaks are attributed to the amorphous regions, as confirmed by their isotropic angular dependence in ARPRS measurements. The three BP modes show pronounced angular variations that differ significantly between the two intercalated samples. In sodium-intercalated BP, A$^{1}_{g}$ and A$^{2}_{g}$ modes retain a dumbbell-like angular dependence under parallel polarization with enhanced anisotropy and reduced symmetry under crossed polarization. At the same time, the B 2g mode transitions from four-lobed (cloverleaf) polar plot to a butterfly-like one. In contrast, lithium-intercalated BP exhibits weaker anisotropy and less distinct angular polar plots for all three modes. These differences reflect the sensitivity of phonon behavior to underlying nanostructure morphology. The vibrational frequencies density of states (FDOS) calculations attribute the B 2g mode transformation to phonon band folding and mode mixing in PNRs. This study demonstrates the power of ARPRS in probing phonon-structure relationships and highlights the influence of edge geometry and quantum confinement on phonon dispersion in PNRs.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2018

Termination Methods for REBCO Tape High-Current Cable Conductors

Three types of joint termination methods for a 2G HTS cable have been developed: YBCO-BSCCO, YBCO-YBCO, and Folding-fan soldered terminations. For the YBCO-BSCCO terminator, each YBCO tape of a cable is connected to a BSCCO tape while the other ends of BSCCO tapes are bundled together and soldered inside a copper tube. The same termination was tested more than 30 times in liquid nitrogen and helium without any problems. It was operated at 10 kA in liquid helium and more than 2 kA in liquid nitrogen. The YBCO-BSCCO termination has been confirmed to be very easy to fabricate and convenient for a cable test since it is reusable. A YBCO tape termination method without BSCCO tape also has been proposed. Both terminations will be very useful for 2G HTS cables. These terminations are demountable if they are not soldered at the junction between tapes. Joint resistance is greatly reduced with increasing applied pressure especially for YBCO-YBCO contact joints. However, in the case of a YBCO-BSCCO joint, the BSCCO tapes may degrade at high pressure. The contact pressure should be optimized to obtain low joint resistance. If the contact surfaces of YBCO-BSCCO and YBCO-YBCO terminations are soldered for a permanent joint, the termination resistances are lower, and better uniformity will be achieved. Another termination is the Folding-fan termination. It is a soldered joint. Joint resistance distributions among cable tapes for these termination methods have been evaluated. Mechanical contact joint resistance distributions between YBCO-BSCCO tapes and YBCO-YBCO tapes have been measured under various contact pressures and contact surface conditions at 77 K. By optimization of the applied contact pressure and contact surface treatment techniques the contact joint resistance of a termination joint can be reduced and a better uniformity can be obtained. We also discussed effects on a cable performance due to no-uniformity of termination resistances, a loop resistance between two tapes in a termination of a cable, and a series operation of two 2G YBCO Twisted Stacked-Tape Cable (TSTC) conductors.

Takayasu, M.↗

NASA NTRS2000

Effects of Gravity on Insect Circadian Rhythmicity

Circadian rhythms - endogenous daily rhythmic fluctuations in virtually all characteristics of life - are generated and coordinated by the circadian timing system (CTS). The CTS is synchronized to the external 24-hour day by time cues such as the light/dark cycle. In an environment without time cues, the length of an animal's day is determined by the period of its internal pacemaker (tau) and the animal is said to be free-running. All life on earth evolved under the solar day; the CTS exists as an adaptation that allows organisms to anticipate and to prepare for rhythmic environmental fluctuations. All life on earth also evolved under the force of earth's gravitational environment. While it is therefore not surprising that changes in the lighting environment affect the CTS, it is surprising that changes in the gravitational environment would do so. However, recent data from one of our laboratories using the brn-3.1 knockout mouse revealed that this model, which lacks the sensory receptor hair cells within the neurovestibular system, does not respond to exposure to a hyperdynamic environment in the same fashion as normal mice. The brn-3.1 mice did not show the expected suppression of circadian rhythmicity shown by control mice exposed to 2G. Exposure to altered ambient force environments affects the amplitude, mean and timing of circadian rhythms in species from unicellular organisms to man. In addition, there is a circadian influence on the homeostatic response to acute 2G acceleration and pulses of 2G can act as a time cue, synchronizing the CTS. This is of significance because maintenance of internal and external temporal coordination is critical for normal physiological and psychological function. Typically, during adaptation to an increased gravitational environment (+G), an initial acute reaction is followed by adaptation and, eventually, a new steady state (14-16), which can take weeks to months to establish. Until the development of space stations, exposure to microgravity was, of necessity, relatively short in duration. In early spaceflight experiments an organism's internal rhythms often expressed periods that were different from each other, even in the presence of a 24.0 hour light-dark cycle, suggesting that the organism was experiencing internal desynchronization (17, 18). In (micro)G, the body temperature rhythm was delayed with respect to other body rhythms and to the light-dark cycle in rhesus macaques (19) and man (20, 21). In the absence of a light-dark cycle, the circadian rhythm of spore formation persisted in Neurospora crassa, however, both the variability and average period of the rhythm increased (22). The beetle Trigonoscelis gigas, exhibited changes in period during and following 11-13 days in (micro)G (23, 24). Resynchronization of the urinary calcium rhythm following a 1800 phase shift of the LID cycle was retarded in rats exposed to (micro)G compared to 1G controls (25). With the development of the Russian Mir Space Station, long-term controlled microgravity exposure became possible. We recorded activity rhythms from black-bodied Tenebrionid beetles, Trigonoscelis gigas, in (micro)G (spaceflight). Each insect was housed individually within an activity monitor (26) and data (activity counts) were collected and stored in five-minute bins. Thirty-two individual activity monitors were housed within each of 2 experimental kits. The beetles within each kit were divided into two groups and the lighting was controlled separately for each group.

Hoban-Higgins, Tana M.↗

NASA NTRS2002

Neurovestibular modulation of circadian and homeostatic regulation: vestibulohypothalamic connection?

Chronic exposure to increased force environments (+G) has pronounced effects on the circadian and homeostatic regulation of body temperature (T(b)), ambulatory activity (Act), heart rate, feeding, and adiposity. By using the Brn 3.1 knockout mouse, which lacks vestibular hair cells, we recently described a major role of the vestibular system in mediating some of these adaptive responses. The present study used the C57BL6JEi-het mouse strain (het), which lacks macular otoconia, to elucidate the contribution of specific vestibular receptors. In this study, eight het and eight WT mice were exposed to 2G for 8 weeks by means of chronic centrifugation. In addition, eight het and eight WT mice were maintained as 1G controls in similar conditions. Upon 2G exposure, the WT exhibited a decrease in T(b) and an attenuated T(b) circadian rhythm. Act means and rhythms also were attenuated. Body mass and food intake were significantly lower than the 1G controls. After 8 weeks, percent body fat was significantly lower in the WT mice (P < 0.0001). In contrast, the het mice did not exhibit a decrease in mean T(b) and only a slight decrease in T(b) circadian amplitude. het Act levels were attenuated similarly to the WT mice. Body mass and food intake were only slightly attenuated in the het mice, and percent body fat, after 8 weeks, was not different in the 2G het group. These results link the vestibular macular receptors with specific alterations in homeostatic and circadian regulation.

NASA Discipline Regulatory Physiology↗

DOE OSTI2016

Exfoliated YBCO filaments for second-generation superconducting cable

The second-generation high temperature superconductor (2G HTS) wire is the most enticing conductor for high-field magnets such as accelerator dipoles and compact fusion devices. The key element of the wire is a thin Y 1 Ba 2 Cu 3 O 7 (YBCO) layer deposited on a flexible metal substrate. The substrate, which becomes incorporated in the 2G conductor, reduces the electrical and mechanical performance of the wire. This is a process that exfoliates the YBCO layer from the substrate while retaining the critical current density of the superconductor. Ten-centimeter long coupons of exfoliated YBCO layers were manufactured, and detailed structural, electrical, and mechanical characterization were reported here. After exfoliation, the YBCO layer was supported by a 75 μ m thick stainless steel foil, which makes for a compact, mechanically stronger, and inexpensive conductor. The critical current density of the filaments was measured at both 77 K and 4.2 K. The exfoliated YBCO retained 90% of the original critical current. Similarly, tests in an external magnetic field at 4.2 K confirmed that the pinning strength of the YBCO layer was also retained following exfoliation.

2G conductors↗