[en] Aromatic and single-olefin six-membered BN heterocycles were synthesized, and the heats of hydrogenation were measured calorimetrically. A comparison of the hydrogenation enthalpies of these compounds revealed that 1,2-azaborines have a resonance stabilization energy of 16.6 1.3 kcal/mol, in good agreement with calculated values.

[en] Highlights: • A feedstock compatible with direct ink write and projection microstereolithography is developed to produce nanoporous ceramics with 250–500 μm features. • Pore sizes ranging from 0.10–500 μm are achieved through the introduction of designed structural porosity and partial sintering. • Printing by both techniques is enabled by modifying solids loading in the range from 55 to 70 wt% to tailor feedstock viscosity. Porous ceramic materials have a wide range of potential applications for which controlling the structure across multiple length scales is desirable. Additive manufacturing (AM) of porous ceramics is therefore of interest for design flexibility. Here, a ceramic ink compatible with 2 AM techniques, projection microstereolithography (PμSL) and direct ink write (DIW), was formulated and demonstrated printed parts with a range of controllable feature sizes as well as nanoporosity resulting from partial sintering. A diacrylate polymer was mixed with 3% yttria partially stabilized zirconia (3YZ) ceramic nanoparticles having different sizes and solids loadings to find formulations that meet the printing requirements of both AM techniques. Detailed rheological studies were used to determine optimal ink formulations to use for either printing method. The resulting 3YZ structures printed with DIW and PμSL have engineered macro cavities with span lengths greater than several millimeters, wall thicknesses of 200 to 540 μm, and porosity within the wall structure on the order of 100 nm. This study revealed that through facile composition changes to the 3YZ ink, it was feasible to use the same ink base for multiple AM techniques without the need for separate cumbersome ink development processes.

[en] Highlights: • Dynamically downscaled Technology Driver Model (TDM) projections are presented. • Widespread decreases in most pollutant concentrations over the U.S. by 2046–2050. • Increases in ozone concentrations due to background CH₄ and NO_x-VOC sensitivity. • Climate changes can either enhance or mitigate O₃ increases, but decrease PM_2.5. • Climate-emissions interplay varies depending on pollutant, season, and U.S. location. In Part II of this work we present the results of the downscaled offline Weather Research and Forecasting/Community Multiscale Air Quality (WRF/CMAQ) model, included in the “Technology Driver Model” (TDM) approach to future U.S. air quality projections (2046–2050) compared to a current-year period (2001–2005), and the interplay between future emission and climate changes. By 2046–2050, there are widespread decreases in future concentrations of carbon monoxide (CO), nitrogen oxides (NO_x = NO + NO₂), volatile organic compounds (VOCs), ammonia (NH₃), sulfur dioxide (SO₂), and particulate matter with an aerodynamic diameter ≤ 2.5 μm (PM_2.5) due mainly to decreasing on-road vehicle (ORV) emissions near urban centers as well as decreases in other transportation modes that include non-road engines (NRE). However, there are widespread increases in daily maximum 8-hr ozone (O₃) across the U.S., which are due to enhanced greenhouse gases (GHG) including methane (CH₄) and carbon dioxide (CO₂) under the Intergovernmental Panel on Climate Change (IPCC) A1B scenario, and isolated areas of larger reduction in transportation emissions of NO_x compared to that of VOCs over regions with VOC-limited O₃ chemistry. Other notable future changes are reduced haze and improved visibility, increased primary organic to elemental carbon ratio, decreases in PM_2.5 and its species, decreases and increases in dry deposition of SO₂ and O₃, respectively, and decreases in total nitrogen (TN) deposition. There is a tendency for transportation emission and CH₄ changes to dominate the increases in O₃, while climate change may either enhance or mitigate these increases in the west or east U.S., respectively. Climate change also decreases PM_2.5 in the future. Other variable changes exhibit stronger susceptibility to either emission (e.g., CO, NO_x, and TN deposition) or climate changes (e.g., VOC, NH₃, SO₂, and total sulfate deposition), which also have a strong dependence on season and specific U.S. regions.

[en] Poly-crystalline germanium (poly-Ge) thin films have potential for lowering the manufacturing cost of photovoltaic devices especially in tandem solar cells, but high crystalline quality would be required. This work investigates the crystallinity of sputtered Ge thin films on glass prepared by in situ growth and ex situ solid-phase crystallization (SPC). Structural properties of the films were characterized by Raman, X-ray diffraction and ultraviolet-visible reflectance measurements. The results show the transition temperature from amorphous to polycrystalline is between 255 deg. C and 280 deg. C for in situ grown poly-Ge films, whereas the transition temperature is between 400 deg. C and 500 deg. C for films produced by SPC for a 20 h annealing time. The in situ growth in situ crystallized poly-Ge films at 450 deg. C exhibit significantly better crystalline quality than those formed by solid-phase crystallization at 600 deg. C. High crystalline quality at low substrate temperature obtained in this work suggests the poly-Ge films could be promising for use in thin film solar cells on glass.

[en] Highlights: • The safety characteristics and at risk inventories in an IFE facility are discussed. • The primary nuclear hazard is the potential exposure of workers and/or the public to tritium and/or neutronically activated products. • Recent technology developments in tritium processing are key for minimization of inventories. • Initial safety studies indicate that hazards associated to the use of liquid lithium can be appropriately managed. • Simulation of worst-case scenarios indicate that the accident consequences are limited and below the limit for public evacuation. - Abstract: Over the past five years, the fusion energy group at Lawrence Livermore National Laboratory (LLNL) has made significant progress in the area of safety and tritium research for Inertial Fusion Energy (IFE). Focus has been driven towards the minimization of inventories, accident safety, development of safety guidelines and licensing considerations. Recent technology developments in tritium processing and target fill have had a major impact on reduction of tritium inventories in the facility. A safety advantage of inertial fusion energy using indirect-drive targets is that the structural materials surrounding the fusion reactions can be protected from target emissions by a low-pressure chamber fill gas, therefore eliminating plasma-material erosion as a source of activated dust production. An important inherent safety advantage of IFE when compared to other magnetic fusion energy (MFE) concepts that have been proposed to-date (including ITER), is that loss of plasma control events with the potential to damage the first wall, such as disruptions, are non-conceivable, therefore eliminating a number of potential accident initiators and radioactive in-vessel source term generation. In this paper, we present an overview of the safety assessments performed to-date, comparing results to the US DOE Fusion Safety Standards guidelines and the recent lessons-learnt from ITER safety and licensing activities, and summarize our most recent thoughts on safety and tritium considerations for future nuclear fusion facilities.

[en] Organ-on-chip platforms aim to improve preclinical models for organ-level responses to novel drug compounds. Heart-on-a-chip assays in particular require tissue engineering techniques that rely on labor-intensive photolithographic fabrication or resolution-limited 3D printing of micropatterned substrates, which limits turnover and flexibility of prototyping. We present a rapid and automated method for large scale on-demand micropatterning of gelatin hydrogels for organ-on-chip applications using a novel biocompatible laser-etching approach. Fast and automated micropatterning is achieved via photosensitization of gelatin using riboflavin-5′phosphate followed by UV laser-mediated photoablation of the gel surface in user-defined patterns only limited by the resolution of the 15 μm wide laser focal point. Using this photopatterning approach, we generated microscale surface groove and pillar structures with feature dimensions on the order of 10–30 μm. The standard deviation of feature height was 0.3 μm, demonstrating robustness and reproducibility. Importantly, the UV-patterning process is non-destructive and does not alter gelatin micromechanical properties. Furthermore, as a quality control step, UV-patterned heart chip substrates were seeded with rat or human cardiac myocytes, and we verified that the resulting cardiac tissues achieved structural organization, contractile function, and long-term viability comparable to manually patterned gelatin substrates. Start-to-finish, UV-patterning shortened the time required to design and manufacture micropatterned gelatin substrates for heart-on-chip applications by up to 60% compared to traditional lithography-based approaches, providing an important technological advance enroute to automated and continuous manufacturing of organ-on-chips. (paper)

[en] Biocompatible/biodegradable hydrogel polymers were immersed in "1"8O-enriched water and "1"6O-water to create "1"8O-water hydrogels and "1"6O-water hydrogels. In both cases, the hydrogels were made of ∼91 wt% water and ∼9 wt% polymer. In addition, 5–8 μm Zn powder was suspended in "1"6O-water and "1"8O-enriched water and cross-linked with hydrogel polymers to create Zn/"1"6O-water hydrogels (30/70 wt%, ∼9 wt% polymer) and Zn/"1"8O-water hydrogels (10/90 wt%), respectively. A block of extra-firm ‘wet’ tofu (12.3  ×  8.8  ×  4.9 cm, ρ  ≈  1.05 g cm"−"3) immersed in water was injected with Zn/"1"6O-water hydrogels (0.9 ml each) at four different depths using an 18-gauge needle. Similarly, Zn/"1"8O-water hydrogels (0.9 ml) were injected into a second tofu phantom. As a reference, both "1"6O-water hydrogels (1.8 ml) and "1"8O-water hydrogels (0.9 ml) in Petri dishes were irradiated in a ‘dry’ environment. The hydrogels in the wet tofu phantoms and dry Petri dishes were scanned via CT and images were used for treatment planning. Then, they were positioned at the proton distal dose fall-off region and irradiated (2 Gy) followed by PET/CT imaging. Notably high PET signals were observed only in "1"8O-water hydrogels in the dry environment. The visibility of the Zn/"1"6O-water hydrogels injected into the tofu phantom was outstanding in CT images, but these hydrogels provided no noticeable PET signals. The visibility of the Zn/"1"8O-water hydrogels in the wet tofu were excellent on CT and moderate on PET; however, the PET signals were weaker than those in the dry environment, possibly owing to "1"8O-water leaching out. The hydrogel markers studied here could be used to develop universal PET/CT fiducial markers. Their PET visibility (attributed more to activated "1"8O-water than Zn) after proton irradiation can be used for proton therapy/range verification. More investigation is needed to slow down the leaching of "1"8O-water. (paper)

[en] The application of spacer gel represents a promising approach to reliably spare the rectal frontal wall during particle therapy (IJROBP 76:1251-1258, 2010). In order to qualify the spacer gel for the clinical use in particle therapy, a variety of measurements were performed in order to ensure the biological compatibility of the gel, its physical stability during and after the irradiation, and a proper definition of the gel in terms of the Hounsfield Unit (HU) values for the treatment planning system. The potential for the use of the spacer gel for particle therapy monitoring with off-line Positron Emission Tomography (PET) was also investigated. The spacer gel implanted to the prostate patient in direct neighbourhood to the clinical target volume does not interfere with the particle therapy treatment planning procedure applied at Heidelberg Ion Beam Therapy Centre (HIT). The performed measurements show that Bragg-peak position of the particles can be properly predicted on the basis of computed tomography imaging with the treatment planning system used at HIT (measured water equivalent path length of 1.011 ±0.011 (2σ), measured Hounsfield Unit of 28.9 ±6.1 (2σ)). The spacer gel samples remain physically unchanged after irradiation with a dose exceeding the therapeutic dose level. The independently measured Bragg-Peak position does not change within the time interval of 10 weeks. As a result of the presented experiments, the first clinical application of spacer gel implant during prostate cancer treatment with carbon ions and protons was possible at HIT in 2012. The reported pre-clinical investigations demonstrate that use of spacer gel is safe in particle therapy in presence of therapy target motion and patient positioning induced particle range variations. The spacer gel injected between prostate and rectum enlarge the distance between both organs, which is expected to clinically significantly decrease the undesirable exposure of the most critical organ at risk, i.e. rectal frontal wall. Further research on the composition of spacer gel material might lead to additional clinical benefits by validation of particle therapy of prostate via post-therapeutic PET-imaging or by patient positioning based on the gel as a radio-opaque marker

[en] Highlights: • Detailed technology-driven transportation emissions are presented for the U.S. • Transportation emissions are projected to decrease by 2046–2050 for the U.S. • On-road vehicles dominate emission changes of CO, NO_x, VOC, and NH₃. • On-road and non-road modes both contribute to SO₂ and particulate emission changes. • Overall good model performance for baseline 2005 WRF/CMAQ simulation. Emissions from the transportation sector are rapidly changing worldwide; however, the interplay of such emission changes in the face of climate change are not as well understood. This two-part study examines the impact of projected emissions from the U.S. transportation sector (Part I) on ambient air quality in the face of climate change (Part II). In Part I of this study, we describe the methodology and results of a novel Technology Driver Model (see graphical abstract) that includes 1) transportation emission projections (including on-road vehicles, non-road engines, aircraft, rail, and ship) derived from a dynamic technology model that accounts for various technology and policy options under an IPCC emission scenario, and 2) the configuration/evaluation of a dynamically downscaled Weather Research and Forecasting/Community Multiscale Air Quality modeling system. By 2046–2050, the annual domain-average transportation emissions of carbon monoxide (CO), nitrogen oxides (NO_x), volatile organic compounds (VOCs), ammonia (NH₃), and sulfur dioxide (SO₂) are projected to decrease over the continental U.S. The decreases in gaseous emissions are mainly due to reduced emissions from on-road vehicles and non-road engines, which exhibit spatial and seasonal variations across the U.S. Although particulate matter (PM) emissions widely decrease, some areas in the U.S. experience relatively large increases due to increases in ship emissions. The on-road vehicle emissions dominate the emission changes for CO, NO_x, VOC, and NH₃, while emissions from both the on-road and non-road modes have strong contributions to PM and SO₂ emission changes. The evaluation of the baseline 2005 WRF simulation indicates that annual biases are close to or within the acceptable criteria for meteorological performance in the literature, and there is an overall good agreement in the 2005 CMAQ simulations of chemical variables against both surface and satellite observations.

[en] Polycrystalline silicon (poly-Si) thin-films are made on planar and textured glass substrates by solid phase crystallization (SPC) of in situ doped amorphous silicon (a-Si) deposited by electron-beam evaporation. These materials are referred to by us as EVA materials (SPC of evaporated a-Si). The properties of EVA poly-Si films are characterised by Raman microscopy, transmission electron microscopy, and X-ray diffraction. A narrow and symmetrical Raman peak at a wave number of about 520 cm^-1 is observed for all samples, showing that the films are fully crystallized. X-ray diffraction (XRD) reveals that the films are preferentially (111)-oriented. Furthermore, the full width at half maximum of the dominant (111) XRD peaks indicates that the structural quality of the films is affected by the a-Si deposition temperature and the surface morphology of the glass substrates. A-Si deposition at 200 instead of 400 deg. C leads to an enhanced poly-Si grain size. On textured glass, the addition of a SiN barrier layer between the glass and the Si improves the poly-Si material quality. No such effect occurs on planar glass. Mesa-type solar cells are made from these EVA films on planar and textured glass. A strong correlation between the cells' current-voltage characteristics and their crystalline material quality is observed