Exploratory development and services for preparing and examining ultrathin polished sections of lunar rocks and particulates, part 1

Development of improved procedures is reported for three classes of lunar materials: dense rocks, breccias, and particulates. High quality ultrathin sections of these materials are obtained. Lists of equipment and supplies, procedures, photomicrographic documentation, and training are provided. Advantages of ultrathin polished sections for conventional and unconventional optical microscopy methods are described. Recommendations are provided for use of ultrathin sections in lunar rock studies, for further refinement of ultrathinning procedures, and for additional training efforts to establish a capability at the Manned Space Center. For Part 2, See N72-50754

Intrinsic point defects and volume swelling in ZrSiO4 under irradiation

The effects of high concentration of point defects in crystalline ZrSiO4 as originated by exposure to radiation, have been simulated using first principles density functional calculations. Structural relaxation and vibrational studies were performed for a catalogue of intrinsic point defects, with different charge states and concentrations. The experimental evidence of a large anisotropic volume swelling in natural and artificially irradiated samples is used to select the subset of defects that give similar lattice swelling for the concentrations studied, namely interstitials of O and Si, and the anti-site Zr(Si), Calculated vibrational spectra for the interstitials show additional evidence for the presence of high concentrations of some of these defects in irradiated zircon.Comment: 9 pages, 7 (color) figure

Experimental Verification of a Cracked Fuel Mechanical Model

This report describes the results of a series of laboratory experiments conducted to independently verify a model that describes the nonlinear mechanical behavior of cracked fuel in pelletized UO{sub 2}/Zircaloy nuclear fuel rods under normal operating conditions. After a brief description of the analytical model, each experiment is discussed in detail. Experiments were conducted to verify the general behavior and numerical values for the three primary independent modelling parameters (effective crack roughness, effective gap roughness, and total crack length), and to verify the model predictions that the effective Young's moduli for cracked fuel systems were substantially less than those for solid UO{sub 2} pellets. In general, the model parameters and predictions were confirmed, and new insight was gained concerning the complexities of cracked fuel mechanics

Data Report for the NRC/PNL Halden Assembly IFA-432: April 1978-May 1980

This report presents the in-reactor data collected from the U.S. Nuclear Regulatory Commission (NRC)/Pacific Northwest Laboratory (PNL) Halden test assembly IFA-432 for the period from April 1978 through May 1980. The irradiation test is part of an experimental program entitled 11 Experimental Support and Development of Single-Rod Fuel Codes" sponsored by the Fuel Behavior Research Branch of the NRC. The purpose of this program is to reduce the uncertainties of predicting the thermal and mechanical behavior of an operating nuclear fuel rod, Fuel centerline temperatures, cladding elongation, internal fuel rod pressures, and local powers at the thermocouple (TC) positions are shown as a function of time. The local powers were derived from neutron detector readings while the other variables were measured directly. Detailed analysis of the data is not made, but topical reports discussing certain aspects of the data are referenced. Descriptions of the assembly, instrumentation and calibration, and data processing methods are also presented

Structure of anhydrotetracycline-bound Tet(X6) reveals the mechanism for inhibition of type 1 tetracycline destructases

Inactivation of tetracycline antibiotics by tetracycline destructases (TDases) remains a clinical and agricultural threat. TDases can be classified as type 1 Tet(X)-like TDases and type 2 soil-derived TDases. Type 1 TDases are widely identified in clinical pathogens. A combination therapy of tetracycline and a TDase inhibitor is much needed to rescue the clinical efficacy of tetracyclines. Anhydrotetracycline is a pan-TDase inhibitor that inhibits both type 1 and type 2 TDases. Here, we present structural, biochemical, and phenotypic evidence that anhydrotetracycline binds in a substrate-like orientation and competitively inhibits the type 1 TDase Tet(X6) to rescue tetracycline antibiotic activity as a sacrificial substrate. Anhydrotetracycline interacting residues of Tet(X6) are conserved within type 1 TDases, indicating a conserved binding mode and mechanism of inhibition. This mode of binding and inhibition is distinct from anhydrotetracycline\u27s inhibition of type 2 TDases. This study forms the framework for development of next-generation therapies to counteract enzymatic tetracycline resistance

Self-Adjusting Biofeedback with a Dynamic Feedback Signal Set (DyFSS)

A lack of control over their autonomic nervous system presents a major challenge for many children with Autism Spectrum Disorder (ASD). Autonomic biofeedback training is a promising treatment for managing anxiety and ASD symptoms more generally. We describe software that tunes four autonomic measurements to the best abilities and needs of each individual patient. Using this dynamic feedback signal set (DyFSS), a strength-based, self-customizing algorithm, we aim to address the autonomic heterogeneity of youth with ASD. The DyFSS may improve autonomic biofeedback training for the user by making it more understandable and easier to accomplish. Because it is self-adjusting, it may also ease the integration of autonomic biofeedback training into clinical work. Initial feasibility testing of this algorithm in youth with ASD with a five-session autonomic biofeedback training protocol showed improved behavior in relation to ASD symptoms Initial reactions show that youth with ASD are readily engaged through technological interventions such as autonomic biofeedback. Keywords— autism spectrum disorder; autonomi

High Burnup Effects Program A State-of-the-Technology Assessment

Various analytical models and empirical correlations describing the fission gas release phenomenon were examined. An evaluation was made of the current pertinent experimental data on the subject of high burnup fission gas release. Data reported by individual investigators were compared and evaluated in relation to their applicability to the content and scope of the High Burnup Effects Program. These evaluations then form the bases for defining the data needs, and the selection of variables to be studied in this program

Sample Science Input to Landing Site Selection for Mars 2020: An In-Situ Exploration and Sample Caching Rover

One of the Mars 2020 Rover mission’s main objectives is to collect samples of martian material and seal them in individual tubes for possible return by a later mission[1]. In order for the M2020 rover to have the highest chances of making a significant discovery from the diverse kinds of geological targets that Mars offers, it is crucial to select a landing site that would put the rover in proximity to these features. The M2020 landing site selection process is open to all [2]; however at this meeting we are seeking input from the sample science community into attributes of the landing site that should be prioritized. This paper seeks to foster broader intellectual inputs from the community, and outputs from this discussion will be provided to the M2020 landing site selection committee