The absorbance and photoluminescence emission of Type 1 quantum dots (QDs). Excitation wavelength is 460 nm. Even with multiple shells, these QDs have red emission that is ideal for SSL applications.

The ideal red emitter would have broad blue absorption and narrowband emission that peaks at ∼610–630 nm and lacks the deep red emission to which the eye is insensitive. The narrowband red emission criterion enables

• a high luminous efficacy of radiation (LER)—defined as the lumens of light emitted per Watt of light emitted and
• warm white light with a high color rendering index and a low correlated color temperature.

Some additional criteria that red emitters must satisfy relate to their performance in a device and include

• high quantum yield under blue excitation;
• low thermal quenching;
• photostability;
• low scattering losses; and
• resistance to saturation under high excitation fluences.

Our goal is to develop red emitters that satisfy all of these criteria for SSL.

For quantum dots to be suitable for demanding applications, such as SSL, heterostructures must be devel­oped that consist of a group II–VI semiconductor core (e.g., cadmium telluride, CdTe) surrounded by one or more group II–VI shell materials, whose purpose is to (a) enhance the quantum yield, (b) reduce thermal quenching, and (c) enhance the thermal and photostability of these materials so that they have a suitable lifetime (target: >30,000 hrs) when subjected to the high excitation fluences characteristic of lighting appli­cations.

CdTe-based quantum dot heterostructures have shown potential as the red-emitting component for warm white LEDs. They have broad blue absorption, narrowband red emission, quantum yield as high as 95.5%, and significantly higher luminous efficacy of radiation than that of the current red LED phosphors. The photo­luminescence emission from Type 1 quantum dots is ideally located at 613 nm and its LER is 227 lm/W_emitted, which is an 87% improvement over a broadband red-emitting Eu²⁺-doped nitridosilicate phosphor.

The effects of aging include a blue-shift and broadening of the photoluminescence, blue-shift of the absorbance, and an increase in the photoluminescence lifetimes. We measured the smallest photoluminescence blue-shift (5 nm) for the Type 2 quantum dots that were aged for one year. Quantum dot polymer encapsulation is expected to improve their photostability and will be a subject of future work.

Type 2 and Type 3 quantum dots that are one year old have significantly less thermal quenching than Type 4 quantum dots at 100 °C. The thermal quenching of Type 1 quantum dots is comparable to that of the Type 2 and Type 3 quantum dots, but is completely reversible. Understanding the mechanisms responsible for thermal quenching in CdTe-based quantum dots above room temperature will help us design heterostructures for SSL applications that minimize or eliminate this effect.

This investigation was conducted by Lauren Shea-Rohwer (in Sandia’s Microsystems Integration Dept.), James Martin (in Sandia’s Nanoscale Science Dept.), and Xichen Cai and David Kelley (at the University of California–Merced) and was funded by Sandia’s Solid-State Lighting Science Energy Frontiers Research Center, funded by the U.S. Department of Energy, Office of Basic Energy Sciences. Their article, “Red-Emitting Quantum Dots for Solid-State Lighting” can be found in the ECS Journal of Solid State Science and Technology (vol 2, issue 2, R3112, 7 pp)

Read the abstract at ECS Journal of Solid State Science and Technology.

Ferroelectric domain orientation maps for 4-domain (a) and 2-domain (b) specimens, with corresponding images of domain boundary types and charging in (c) and (d) revealing the substantial domain wall den-sity difference for distinct polarization variants. The 200 nm scale bars in (a) and (b) apply to all images for each specimen (columns).

Ferroelectric and ferroelastic domain structure has a profound effect on the piezoelectric, ferro­electric, and dielectric responses of ferroelectric materials. These responses drive the development of capacitors, nonvolatile memory, sensors, and tunnel junctions. Recently, progress in thin-film growth of materials using these ferroelectric effects promises nov­el nanoscale device applications. Much recent interest is focused on bismuth ferrite (BiFeO₃), a rhombohe­drally distorted perovskite exhibiting room-temperature coexistence of ferroelectric and antiferromagnetic orders, yielding many unusual properties.

Several studies show it is possible to engineer the domain structure of epitaxial BiFeO₃ films using SrTiO₃ single-crystalline substrates and by using symmetry breaking step edges resulting from intentional miscuts along high-symmetry crystallographic directions. Given the growth- and substrate-dependent domain structures that BiFeO₃ exhibits, its properties and responses to various stimuli can be affected by the pres­ence of the various domain walls. These properties must be considered and well characterized as BiFeO₃ thin films are considered for use in various nanometer-scale devices.

Our team measured the thermal conductance of a series of BiFeO₃ thin films with different domain variants. Piezo force microscopy (PFM) revealed a corresponding variation in the average domain wall density, based on polarization mapping that allows domain wall identification, local polarization rotation, and interfacial charging to be determined with 4.5 nm resolution. We measured the thermal conductance of the BiFeO₃ films with time domain thermoreflectance (TDTR) from 100–400 K.

The effective thermal conductivities we observed in the BiFeO₃ films varied based on the density of domain walls in the thin film, where the presence of more domains leads to a decrease in thermal conductivity, indi­cating the strong effect domain walls have on phonon scattering and thermal conductance even though do­main walls are generally considered to be nearly perfect interfacial regions. The thermal boundary conduc­tances across the coherent domain walls are lower than the thermal boundary conductances associated with grain boundaries in silicon, strontium titanate, and yttria-stabilized zirconia (YSZ). At higher tempera­tures, the effective thermal conductivity of the 4-domain variant BiFeO₃ thin films is roughly equivalent to the thermal conductivity of silicon dioxide.

Future work in domain wall thermal engineering should focus on studying the influence of domain wall type, domain characteristics (charged or neutral), and population on thermal transport to optimize the performance of practical devices.

Read the abstract at Applied Physics Letters.

Reflection high energy electron diffraction (RHEED) images measured along the substrate <11‾20> direc­tion during the growth of a 40-nm-thick La₂O₃ film. Images represent the following stages of growth: (a) bare (0001)-oriented GaN, (b) 2 nm of La₂O₃, (c) 3 nm La₂O₃, (d) 5 nm La₂O₃, (e) 10 nm La₂O₃, & (f) 40 nm La₂O₃. Arrows indicate secondary diffrac­tion spots that are attributed to a cubic polymorph.

Sandians

• Jon Ihlefeld (in the Electronic, Optical, & Nanostructured Materials Dept.),
• Mike Brumbach (in the Materials Characterization and Performance Dept.), and
• Stan Atcitty (in the Energy Storage Technology and Systems Dept.)

recently published the article “Band offsets of La₂O₃ on (0001) GaN grown by reactive molecular-beam epitaxy” in Applied Physics Letters outlining research to prepare high-dielectric-constant gate oxides on gallium nitride (GaN).

Preparation of high-quality gate oxides on wide bandgap semiconductors remains an important barrier/challenge toward realizing efficient high-performance power elec­tronic devices such as metal-oxide-semiconductor (MOS) field effect transistors (MOSFETs).

Several factors make oxide integration difficult. For GaN electronics, in particular, the lack of a low-defect-density native oxide interface and the limited number of compati­ble oxides that have a sufficiently large bandgap to mini­mize electrical leakage are significant hurdles for oxide integration. Lanthanide series oxides are a potential group of materials that may be promising for use in gate insulator applications. These oxides possess relatively large band­gaps and permittivity values as high as 30.

The team prepared La₂O₃ films on (0001)-oriented GaN substrates via reactive molecular-beam epitaxy and assessed film orientation and phase using reflection high-energy electron and X-ray diffraction (RHEED). Films were observed to grow as predominantly hexagonal La₂O₃ for thicknesses less than 10 nm while film thickness greater than 10 nm favored mixed cubic and hexagonal symmetries. The team characterized band offsets by X-ray photoelectron spectroscopy on hexagonally symmetric films and measured valence band offsets of 0.636±0.04 eV at the La₂O₃/GaN interface. A conduction band offset of approximately 1.5 eV could be inferred from the measured valence band offset.

The measured valence band offset at the interface between hexagonal La₂O₃ and (0001)-oriented GaN is slightly larger than the 0.4 eV valence band offset measured for the high-permittivity Sc₂O₃/GaN interface, which suggests that this larger valence band offset may be promising for device applications. However, growth challenges associated with the interplay between dielectric layer thickness, film roughness, and cubic polymorph formation may make La₂O₃ a poor choice as a gate dielectric for a GaN metal-oxide-semiconductor device.

The research was funded through the U.S. Department of Energy’s Office of Electricity Delivery and Energy Reliability (OE) Energy Storage Program.

Read the abstract at Applied Physics Letters.

The Seebeck effect is the conversion of temperature differences directly into electricity, named after German physicist Thomas Johann Seebeck.

Their instrument will enable an understanding of the roles of oxygen vacancies and intentional dopants on the thermopower of oxide thermoelectrics properties and aid in processing and packaging oxide thermoelectric materials for high-temperature applications.

Aerial view of the Fukushima plant area in 1975, showing separation between Units 5 & 6 and the majority of the complex. (National Land Image Information color aerial photographs, Ministry of Land, Infrastructure, Transport, and Tourism.)

Jeff Cardoni (in the Severe Accident Analysis Dept.) presented the paper “MELCOR Simulations of the Severe Accident at the Fukushima 1F3 Reactor” at the 2012 ANS Winter Meeting and Nuclear Technology Expo, which held an embedded topical meeting called “International Meeting on Severe Accident Assessment and Management: Lessons Learned From Fukushima Daiichi.” on November 11–15, 2012, in San Diego, California, where it received the “Outstanding Paper Award.”

In response to the accident at the Fukushima Daiichi nuclear power station in Japan, the U.S. Nuclear Regulatory Commission and Department of Energy jointly sponsored an accident reconstruction study to assess the MELCOR code’s severe accident modeling capability. Project objectives included reconstruction of the accident progressions using computer models and accident data and validating the MELCOR code and the Fukushima models against plant data.

MELCOR appears well-suited for reproducing the thermal-hydraulic response of the severe accident at 1F3. Using the current Sandia MELCOR 2.1 model of 1F3, the code calculates reactor pressure vessel pressures and containment that agree reasonably well with the Tokyo Electric Power Company (TEPCO) data. Given rough agreement with the TEPCO data and the reactor building explosion, MELCOR predicts the degree of core damage in 1F3 and the associated radionuclide release to the environment.

In capturing the principal boundary conditions for the 1F3 simulations, it is apparent that both the quantity and timing of hydrogen generation are important. A rapid hydrogen generation rate increases containment pressures (with safety relief valves open) and allows the simulation of flammable conditions in the reactor building. Numerous alternatives can explain the explosion, even beyond the standby gas treatment system and ex-vessel scenarios that have not yet been successfully modeled. However, there is significant forensic value in investigating each plausible scenario individually. The MELCOR code can be used to identify which scenarios are possible (or even likely), assuming the current 1F3 model and the TEPCO data are in reasonable agreement.

The Fukushima Daiichi accidents highlight some potential areas for MELCOR code improvement. Most importantly, the MELCOR models for lower head failure may need to be extended to provide higher-fidelity simulations of scenarios involving gradual melt-through of vessel penetrations; in such scenarios, the use of the gross-failure model, even in conjunction with the simple penetration failure model, may never predict vessel rupture and may therefore be too optimistic.

Severe accident codes such as MELCOR provide a valuable means of characterizing severe nuclear accidents. Uncertainty and variability ensure that such analyses will render wide variations in predicted accident progressions, and this is a reflection of true variability in the potential responses of complex systems undergoing severe accident conditions.

This paper’s authors included Jeff Cardoni, Randall Gauntt, Donald Kalinich, and Jesse Phillips (all in the Severe Accident Analysis Dept.).

Power generating plants are often located near large sources of fresh water that they use as coolant for the power-generation cycle.

Energy policymakers worldwide should look beyond supply security and environmental questions and consider water resource availability if they expect to succeed, experts said May 3 during a forum at the Woodrow Wilson International Center for Scholars. “Water has become the Achilles heel of some energy projects,” said M. Michael Hightower, head of the Water for Energy Project at Sandia National Laboratories in Albuquerque. “Many of the world’s energy resources are in very dry areas. We have to start coming up with solutions now,” he said. Supplies are growing increasingly scarce in many U.S. basins, he noted during the forum, “The Thirsty Triangle: The Water Footprint of Energy Trade Between China, Canada, and the United States.”

Every country depends on a sustainable supply of water and energy and these two resources are inextricably linked. The production of all energy sources uses water but coal, oil sands, biofuels, and shale gas have particularly large water footprints. Absent tight regulations these sources of energy can also create serious water pollution. Conversely, water treatment and distribution require considerable energy—for example the state of California uses nearly 20% of its energy to clean and transfer water. China, Canada, and the United States face significant obstacles in their efforts to provide clean, affordable energy. China is heavily dependent on coal, which according to research by the Wilson Center and Circle of Blue, accounts for 20% of the country’s water use, exacerbating pressure on the country’s already vulnerable water resources. In the United States thermal power plants use 40% of freshwater resources for once-through cooling, making them vulnerable in times of drought. Oil sands development in Canada demands a water intensive extraction and refining process, and makes up a large and growing portion of U.S. oil imports from Canada.

At this May 3 Canada Institute/China Environment Forum meeting, speakers cast a broad net examining the water footprint of energy development within Canada, the United States, and China and how energy trade among these three countries is being shaped by water constraints.

Read the rest of the article at Oil & Gas Journal.

Visit the Wilson Center for more information about this event or to view their webcast.

Sandia’s NISAC facility.

Sandia was mentioned in a letter by Representative Sheila Jackson Lee (D-TX) for outstanding work with Texas Southern University (TSU). Through the National Infrastructure Simulation and Analysis Center (NISAC) program, Sandia has partnered with TSU’s National Transportation Center of Excellence, to complete analyses of the petrochemical supply chain and related analyses of the impact of infrastructures.

Representative Lee writes: “As a long-time resident of Houston, Texas, known by many as the Energy Capital of the World, the important work at TSU, including the Petrochemical Supply Chain and Incident Analysis project (with Sandia National Laboratories and the Texas Transportation Institute) and the Petrochemical Incident Location System (PILS), is why the Center is especially of interest to me, my constituency and the Houston community at large.”

The Molten Salt Test Loop at Sandia’s National Solar Thermal Test Facility.

Bridgers & Paxton Consulting Engineers, Inc., of Albuquerque, N.M., earned a National Recognition Award for exemplary engineering achievement in the American Council of Engineering Companies’ (ACEC) 47th annual Engineering Excellence Awards for the Molten Salt Test Loop (MSTL) project, part of Sandia’s NSTTF.

Designed and built to exacting specifications, Sandia’s MSTL system provides a means to perform accelerated lifetime testing on power plant-size components, reducing start-up risks to newly constructed generation facilities. No other test facility in the world is capable of supporting such extensive, large-scale research.

All 146 National Recognition Award winners were honored as preeminent 2013 engineering achievements at the black-tie Engineering Excellence Awards Gala—known as the “Academy Awards of the engineering industry”—held Tuesday, April 23, 2013, at the Grand Hyatt Hotel in Washington, D.C.

This August 3 aerial shot released by the Louisiana Department of Natural Resources shows the sinkhole near Bayou Corne, Louisiana, which has grown since it first began forming in August. Sandia researcher David Borns is part of a group of experts providing technical evaluations about possible causes and remedies for the sinkhole. (Photo courtesy of Louisiana Department of Natural Resources)

Secretary Stephen Chustz, from the Louisiana Department of Natural Resources (LADNR), asked David Borns (in Sandia’s Geotechnology and Engineering Dept.) to serve on the blue ribbon commission (BRC) that was formed by Governor Bobby Jindal to provide science-based public safety recommendations regarding the sinkhole in the Bayou Corne area. The BRC will help LADNR continue making progress to protect the Bayou Corne community and environment.

According to Secretary Chustz, “Members of the Commission hail from all over the world, and we’ve brought together the best knowledge available to work on these safety recommendations.” The BRC will study three primary areas: “the levels of shallow gas in the aquifer, the current and future stability on the western side of Napoleonville Salt Dome, and the management and containment of the sinkhole coupled with the determination of potential void spaces below the sinkhole.”

Read the October 15, 2012 news post.

POF Darts wraps around a computational simulation of a device, evaluating it at particular parameter values, such as uncertain environmental conditions and varying as-manufactured device characteristics. These evaluations are interpolated to build an estimate of the conditions under which the device fails, and their likelihood of occurrence (i.e., the POF).

Reducing the number of simulations required is important because each may be an expensive supercomputer run. Initial experiments indicate that POF Darts offers at least an order of magnitude improvement over the common alternative, Latin Hypercube Sampling, in terms of the number of simulations needed to obtain the same relative accuracy. The advantage grows for small failure probabilities and large sample budgets.

How POF Darts reduces the expense so dramatically comes from two innovations, borrowed from the field of computational geometry and applied to POF for the first time.

• The first innovation is to model failure or not-failure neighborhoods as spheres around evaluation points. Spheres cover wide swaths of the domain that need no further exploration. The remaining exploration is efficiently guided toward the critical failure boundary. The volume of the union of spheres estimates the POF.
• The second innovation is to gain more information about the union-volume per sample, by evaluating the set of spheres analytically along lines, rather than just at single points as in standard Monte Carlo sampling.

Sandia’s Hope Michelsen.

The April 9 issue of EOS, Transactions of the American Geophysical Union, ran a news item in their “Geophysisicists Honors” section about Hope Michelsen’s (in the Combustion Chemistry Dept.) induction into the Alameda County Women’s Hall of Fame ([94(15), p 144], announced here in February). The American Geophysical Union is the world’s largest professional society for geophysicists and atmospheric scientists, with more than 60,000 members.

A screenshot from the 2-year AMIP (Atmospheric Model Intercomparison Project) precipitable water animation simulation run of the NSF/DOE Community Atmosphere Model (CAM5).

The Community Earth System Model (CESM) is a state-of-the-art global climate model being developed with the support of the National Science Foundation and the Department of Energy and used for climate-change science and assessments. Sandia has been leading a multilaboratory effort to develop a new “dynamical core” for CESM’s atmospheric component. This new dynamical core is based on the spectral element method and dramatically increases the scalability of the whole Earth System Model, making higher-resolution simulations possible on DOE’s Leadership computing facilities.

This development work’s final component was to update the numerical discretization to use a “vertically Lagrangian” approach that can better handle the sharp temperature gradients, resulting in an improved treatment of stratocumulus clouds. With this improvement, the model’s spectral element configuration became competitive in terms of simulation quality with the older approaches, while achieving unmatched supercomputer performance. It is scheduled to be included in the May 2013 CESM public release.

σ_xx vs σ_xy at B = 20 T (blue dots), 25 T (black squares), and 30 T (red diamonds). Gray circles are defined by (σ_xx − N)² + σ_xy² = N², with N = 1, 2, 3, and 4.

Historically, type-II InAs/GaSb heterostructures have been extensively studied for infrared applications. With the new prediction as a 2D TI, this material system is believed to hold great potential for future quantum computation. In their article, the team presents their recent quantum transport results around the charge neutrality point (CNP) in a type-II InAs/GaSb field-effect transistor.

Charged carrier (electron and hole) transport shows noisy behavior around the CNP at extremely high B fields. When the diagonal conductivity σ_xx is plotted against the Hall conductivity σ_xy, an unexpected conductivity circle law is observed (see figure). A better understanding of this new conductivity circle law is expected to lead to better quantum applications.

The article’s authors are Wei Pan and Sungkwun Lyo (both in the Quantum Phenomena Dept.), John Klem and Jin Kim (both in the RF Optoelectronics Dept.), Madhu Thalakulam (formerly in the Quantum Phenomena Dept., now at the India Institute of Science), and Mike Cich (formerly in the RF Optoelectronics Dept.).

This work was supported by the DOE Office of Basic Energy Sciences. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the U.S. and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

Matthew Lave is a Ph.D. student at the University of California, San Diego (UCSD). Matthew’s research focuses on variability analysis of solar radiation and solar power. His Ph.D. thesis is exploring upscaling and downscaling solar radiation time series using wavelets.

Sandians Mathew Lave and Joshua Stein ( both in the Photovoltaics and Distributed Systems Dept.) along with Jan Kleissl (University of California–San Diego) published “A Wavelet-Based Variability Model (WVM) for Solar PV Power Plants” in the April 2013 IEEE Transactions issue. (Matthew Lave was a Sandia student intern when this work was being done and will be a new staff member starting at the end of April. This work was part of his Ph.D. thesis.)

Their article presents a wavelet variability model (WVM) for simulating solar photovoltaic (PV) power plant output given a single irradiance point sensor time series using spatio-temporal correlations. Their work simulated the variability reduction (VR) that occurs in upscaling from the single point sensor to the entire PV plant at each time scale, then combined the results with the wavelet transform of the point sensor time series to produce a simulated power plant output.

The WVM is validated against measurements at a 2-MW residential rooftop distributed PV power plant in Ota City, Japan, and at a 48-MW utility-scale power plant in Copper Mountain, Nevada. The WVM simulation matches the actual power output well for all variability time scales, and the WVM compares well against other simulation methods.

Read the article at IEEE Transactions on Sustainable Energy.

Sandia combustion researchers Craig Taatjes and David Osborn discuss data found from the detection and measurement of Criegee intermediate reactions. The apparatus seen on the left was used to make the measurements, which researchers believe will substantially impact existing atmospheric chemistry. (Photo by Dino Vournas)

Hydrocarbons that are emitted into Earth’s troposphere, either naturally or by humans, are removed by many reactive atmospheric species. For unsaturated hydrocarbons—molecules with at least one C=C double bond—a prominent removal mechanism is reaction with ozone, called ozonolysis. It is accepted that ozonolysis produces other reactive species, including carbonyl oxides, which are known as Criegee intermediates. Rudolf Criegee, a German chemist, first proposed the mechanism of ozonolysis in the 1950s.

Because so much ozonolysis happens in the atmosphere, the reactions of Criegee intermediates are thought to be very important in a wide range of tropospheric processes like secondary organic aerosol formation and nighttime production of highly reactive OH radicals. As a result, the chemistry of these reactive Criegee intermediates has been the subject of intense investigation for decades, but without any direct measurement of their reaction rates until last year’s published work by Sandia and its collaborators.  That earlier research was featured in the January 13, 2012, edition of Science. A short video featuring two Sandia researchers describing the work can be seen here.

Sandia combustion chemist Craig Taatjes (in the Combustion Chemistry Dept.), the lead author on the Science papers, said there are several significant aspects about the new research findings. In particular, the measurements show that the reaction rate depends dramatically on whether the CH₃CHOO is bent, with the CH₃– and –OO ends pointing toward the same side, a conformation called “syn–” or more straightened, with the CH₃– and –OO ends pointing away from each other, called “anti–”. “Observing conformer-dependent reactivity represents the first direct experimental test of theoretical predictions,” said Taatjes. “The work will be of tremendous importance in validating the theoretical methods that are needed to accurately predict the kinetics for reactions of Criegee intermediates that still cannot be measured directly.”

The research was funded by the U.S. Department of Energy’s Office of Science and conducted using the Advanced Light Source, a scientific user facility also supported by the DOE Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the U.S. and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

Read the Sandia news release.

Read the paper at Science magazine.

Erecting DOE/SNL tower #1 at the SWiFT facility.

The U.S. Department of Energy and Vestas R&D have completed construction of a new state-of-the-art wind plant research facility at Texas Tech University in Lubbock, Texas. The Scaled Wind Farm Technology (SWiFT) facility is the first U.S. facility specifically designed and constructed to tackle the challenges of the DOE Wind Farm of the Future program.

Three highly modified and upgraded wind turbines will serve as the first phase of an effort to understand the complex wind flow and wind-turbine wakes within a wind plant. R&D from this facility will reduce the cost of wind energy by reducing aerodynamic losses from turbine-to-turbine interaction, enhance energy capture, and mitigate turbine damage.

Vestas and DOE/SNL assembled towers and nacelles for advanced rotor development and accelerated technology deployment at the DOE/SNL Scaled Wind Farm Technology (SWiFT) facility on the grounds of Texas Tech University in Lubbock, Texas.

Construction of the pier-style turbine foundations was completed in December. After this foundation concrete was fully cured, the towers were erected in February. To enable cutting-edge research, engineers worked through the night to perform detailed characterization of the tower and foundations. Following tower characterization, the nacelles were assembled onto each tower to complete the SWiFT’s turbine-nacelle assembly phase.

During early March, Vestas and Sandia worked together to shake down all operational and emergency systems on the heavily prototyped machines before finally erecting the turbine rotors. At the same time, two anemometer towers were erected to allow researchers to measure the 3-D flow through and above the rotor. Now completed, the facility is currently undergoing shake-down and performance testing and will be ready for Wind Farm of the Future R&D activities by mid to late May 2013.

From left, Sandia computer scientists Brian Adams, Jim Stewart, and John Siirola look over the results of a Dakota optimization study. Caterpillar Inc.’s interest in Dakota, an open-source software tool developed by Sandia, launched talks that led to the CRADA signing. (Photo by Norman Johnson)

Sandia and industrial giant Caterpillar Inc. have signed their first umbrella cooperative research and development agreement (CRADA), opening the door to a wide range of scientific research. “This agreement will lead to an expanded relationship with Caterpillar,” said Vic Weiss, the Sandia business development specialist who helped negotiate the CRADA. “It’s a strategic collaboration.”

The Labs had a pair of standard CRADAs with Caterpillar a decade ago, each dealing with a specific project in diesel combustion. The umbrella CRADA has a broader scope, covering multiple projects in a variety of categories over three years. The CRADA authorizes work in computer and computational science, information and data analysis, mathematics, engineering science, and high-performance computing. Technical categories include simulation design exploration, advanced analytics, multi-physics engineering modeling and simulation and high-performance computing.

The agreement includes training, education, technical support and staff visits. “We’re excited about this new CRADA. We hope to do many new projects with Caterpillar in different technical areas,” Weiss said. “These agreements benefit our partners and Sandia by allowing us to do more research and advance our scientific knowledge. We learn when we partner with industry.”

Read the Sandia news release.

Sandia National Laboratories’ Tom Reichardt, left, and Aaron Collins, center, chat with John McGowen of the Arizona Center for Algae Technology and Innovation (AzCATI). Sandia has developed several complementary technologies to help the algae industry in detecting and recovering from pond crashes, and is making use of the AzCATI test-bed facility to collect data and apply its technologies. (Photo by Steffan Schulz)

Sandia is developing a suite of complementary technologies to help the emerging algal biofuels industry detect and quickly recover from algal pond crashes, an obstacle to large-scale algae cultivation for potential biofuels. Sandia is addressing the algal pond crash issue in three complementary ways:

1. developing a real-time monitoring tool for algal ponds that can detect indications of a problem days in advance of a crash,
2. successfully applying pathogen detection and characterization technologies honed through the Sandia’s Rapid Threat Organism Recognition (RapTOR) work, and
3. employing its innovative SpinDx diagnostic device to dig deeper into problems after they’ve occurred and help to identify specific biological agents responsible for crashes.

Sandia’s Tom Reichardt (Remote Sensing and Energetic Materials Dept.), a researcher who works in the Sandia’s remote sensing unit, led development of an online algal reflectance monitor through an internally funded project. The instrument continuously analyzes the algae’s concentration levels, examines its photosynthesis, and performs other diagnostics. This real-time monitoring can warn pond operators when the ponds have been attacked, but it may not be able to identify the attacker.

To help pinpoint problems, a Sandia team led by researcher Todd Lane (Systems Biology Dept.) recently developed a process to quickly and accurately identify pond crash agents through ultra-high-throughput sequencing using RapTOR. “It’s important for the growth of an algal industry to develop a method where algal pond operators can learn immediately when there’s a problem with their ponds from a biological agent standpoint,” said Lane. A Sandia team led by researcher Jeri Timlin (Bioenergy and Defense Technologies Dept.), in collaboration with the University of Nebraska’s Van Etten Lab, enhanced the RapTOR diagnostics by studying certain viral interactions with algal cells. They identified signatures that could provide early detection and subsequent mitigation of algal pond viral infections.

A device like Sandia’s SpinDx could run early detection tests for algal pond operators whenever they sensed instability in their ponds. Issues could then be investigated more thoroughly, with SpinDX helping to determine the root biological cause of the problem. (Photo by Jeff McMillan)

The Sandia process involves a central facility where pond operators would send algal pond samples. Lane’s team applied SpinDx, a device developed by other Sandia/California researchers that can (among other features) analyze important protein markers and process up to 64 assays from a single sample, all in a matter of minutes. Pond operators could regularly use a SpinDx-like device to run early detection tests. They could then provide samples to an off-site facility, which in turn would send back assays to allow the operator to investigate a problem more thoroughly and ward off pond crashes before they occur. “That’s the beauty of SpinDx,” said Lane. “The disks are inexpensive, require little technical expertise, and can be manipulated by nonscientists.”

Now that the core principles of pathogen detection and characterization technologies for pond crash forensics have been successfully proven, the next step will be to conduct more robust demonstrations. Lane’s and Reichardt’s groups are continuing their work as part of the Algae Testbed Public-Private Partnership (ATP³) led by Arizona State University (ASU), the first national algae testbed. The Sandia team will apply the technologies, collect more data, and seek additional collaborations. “Our results over these past couple of years have been compelling, but now we need to deploy the technology into real-world ponds,” Lane explains.

Read the Sandia news release.

Sandia National Laboratories’ Lennie Klebanoff says he feels a personal responsibility to inform technical readers and the public about the urgent need to get zero-emission hydrogen technology into the nation’s vehicles and other carbon-producing applications. (Photo by Dino Vournas)

Sandia reveals the breadth of its hydrogen fuel expertise in the recently published Hydrogen Storage Technology—Materials and Applications. Sandia researcher Lennie Klebanoff (Hydrogen and Combustion Technologies Dept.) is confident that the book will give readers a sense of urgency about the need to get zero-emission hydrogen fuel cell vehicles on the road, and to get other hydrogen-based power equipment into the marketplace.

Klebanoff, who serves as the book’s editor and co-wrote half the chapters, was director of the Metal Hydride Center of Excellence, one of three DOE Hydrogen Storage Centers of Excellence dedicated to solving the problem of storing hydrogen on automobiles. This Center, competitively selected and funded through the DOE Office of Energy Efficiency and Renewable Energy (EERE), included 21 partners from industry, academia, and national laboratories from 2005 through 2010.

Klebanoff drew upon the considerable hydrogen expertise at Sandia/California to complete the book. Sandia’s Daniel Dedrick (Hydrogen and Fuel Cell Technologies Program Manager), Terry Johnson (Energy Systems Engineering and Analysis Dept.), and Vitalie Stavila (Hydrogen and Combustion Technologies Dept.) each contributed to various chapters, and now-retired Sandia hydrogen program manager Jay Keller co-wrote a pair of chapters as well. “It was a real team effort and clearly shows the level and breadth of hydrogen knowledge here at Sandia,” Klebanoff said.

In addition to the Sandia authors, 21 others contributed, including authors from Lawrence Livermore National Laboratory and from other countries including Canada, China, and the United Kingdom. “I felt strongly it was important to have an international perspective, as our energy issues are global and interconnected,” said Klebanoff.

Read the Sandia news release.

The 2013 Asian-American Engineer of the Year awardees. Sandia’s Dr. Jeffrey Tsao is fourth from the right (standing).

Dr. Tsao, a Distinguished Member of Sandia’s Technical Staff in the Semiconductor and Optical Sciences Department, is one of eight distinguished engineers upon whom this award was conferred this year by the AAEOY organization. He received this honor for, “sustained contributions to compound semiconductor materials and device science and exemplary contributions to solid-state lighting technology.” The AAEOY Award is a National Engineers Week Program to recognize the outstanding Asian-American professionals for their leadership, technical achievements, and remarkable public services in the fields of science, technology, engineering, and mathematics (STEM). The annual AAEOY events are supported by industry leaders, national laboratories, technical communities, academia, government agencies, and prominent U.S. companies. Some 600 distinguished guests, corporate executives, and community leaders attended the March 2nd award ceremony.

Dr. Tsao’s career has spanned three phases, each lasting about a decade. From 1981 to 1991, he was a research staff starting at MIT-Lincoln Laboratory and moving on to Sandia National Laboratories. During this period he focused on research publishing close to 100 journal articles and a research monograph entitled “Materials Fundamentals of Molecular Beam Epitaxy.”

Sandia’s Dr. Jeffery Tsao.

During the next decade from 1991 to 2001, he broadened his scope firstly as research manager at Sandia National Laboratories, and secondly, on entrepreneurial leave, as Vice-President of R&D at E20 Communications which is a U.S.-based pre-IPO fiber communications components company. During this phase of his career, he built world-class teams and programs on “smart” compound semiconductor epitaxy and devices for high-speed communications.

Dr. Tsao returned to Sandia National Laboratories in 2001 as research staff, where he currently is with a broader focus, working on white papers and reports with an aim to influence larger national and global research directions. He has helped the DOE Office of Science and Office of Energy Efficiency and Renewable Energy coordinate workshops and roadmaps in various areas of energy science and technology. He is an early pioneer in solid-state lighting, a technology poised to transform how the world consumes 20% of its electricity. Along the way, he has outlined new and counterintuitive ways of thinking about the energy economics of lighting. He continues his career at Sandia National Laboratories as a Distinguished Member of Technical Staff, and Chief Scientist of its Energy Frontier Research Center for Solid-State-Lighting Science.

Dr. Tsao is married to Sylvia, and they have two children.