Thoriated nickel bonded by solid-state diffusion method

Solid-state diffusion bonding in an inert-gas atmosphere forms high-strength joints between butting or overlapping surfaces of thoriated nickel. This method eliminates inert-phase agglomeration

Evaluation of Superplastic Forming and Weld-brazing for Fabrication of Titanium Compression Panels

The two titanium processing procedures, superplastic forming and weld brazing, are successfully combined to fabricate titanium skin stiffened structural panels. Stiffeners with complex shapes are superplastically formed using simple tooling. These stiffeners are formed to the desired configuration and required no additional sizing or shaping following removal from the mold. The weld brazing process by which the stiffeners are attached to the skins utilize spot welds to maintain alignment and no additional tooling is required for brazing. The superplastic formed/weld brazed panels having complex shaped stiffeners develop up to 60 percent higher buckling strengths than panels with conventional shaped stiffeners. The superplastic forming/weld brazing process is successfully scaled up to fabricate full size panels having multiple stiffeners. The superplastic forming/weld brazing process is also successfully refined to show its potential for fabricating multiple stiffener compression panels employing unique stiffener configurations for improved structural efficiency

Curved cap corrugated sheet

The report describes a structure for a strong, lightweight corrugated sheet. The sheet is planar or curved and includes a plurality of corrugation segments, each segment being comprised of a generally U-shaped corrugation with a part-cylindrical crown and cap strip, and straight side walls and with secondary corrugations oriented at right angles to said side walls. The cap strip is bonded to the crown and the longitudinal edge of said cap strip extends beyond edge at the intersection between said crown and said side walls. The high strength relative to weight of the structure makes it desirable for use in aircraft or spacecraft

Fabrication and evaluation of cold/formed/weldbrazed beta-titanium skin-stiffened compression panels

The room temperature and elevated temperature buckling behavior of cold formed beta titanium hat shaped stiffeners joined by weld brazing to alpha-beta titanium skins was determined. A preliminary set of single stiffener compression panels were used to develop a data base for material and panel properties. These panels were tested at room temperature and 316 C (600 F). A final set of multistiffener compression panels were fabricated for room temperature tests by the process developed in making the single stiffener panels. The overall geometrical dimensions for the multistiffener panels were determined by the structural sizing computer code PASCO. The data presented from the panel tests include load shortening curves, local buckling strengths, and failure loads. Experimental buckling loads are compared with the buckling loads predicted by the PASCO code. Material property data obtained from tests of ASTM standard dogbone specimens are also presented

Glass bead shot peening retards stress corrosion failure of titanium tanks

Rigidly controlled shot peening retards the incompatibility between titanium alloys and nitrogen tetroxide in rocket-propellant storage tanks. This sets up a residual compressive stress in the surface of a material which reduces tensile stresses in the material fibers, alleviating stress corrosion

Controlled glass bead peening Patent

Method and apparatus for inducing compressive stresses in pressure vessel to prevent stress corrosio

Level Set Approach to Reversible Epitaxial Growth

We generalize the level set approach to model epitaxial growth to include thermal detachment of atoms from island edges. This means that islands do not always grow and island dissociation can occur. We make no assumptions about a critical nucleus. Excellent quantitative agreement is obtained with kinetic Monte Carlo simulations for island densities and island size distributions in the submonolayer regime.Comment: 7 pages, 9 figure

Spatially distributed water-balance and meteorological data from the Wolverton catchment, Sequoia National Park, California

Accurate water-balance measurements in the seasonal, snow-dominated Sierra Nevada are important for forest and downstream water management. However, few sites in the southern Sierra offer detailed records of the spatial and temporal patterns of snowpack and soil-water storage and the fluxes affecting them, i.e., precipitation as rain and snow, snowmelt, evapotranspiration, and runoff. To explore these stores and fluxes we instrumented the Wolverton basin (2180-2750 m) in Sequoia National Park with distributed, continuous sensors. This 2006-2016 record of snow depth, soil moisture and soil temperature, and meteorological data quantifies the hydrologic inputs and storage in a mostly undeveloped catchment. Clustered sensors record lateral differences with regards to aspect and canopy cover at approximately 2250 and 2625 m in elevation, where two meteorological stations are installed. Meteorological stations record air temperature, relative humidity, radiation, precipitation, wind speed and direction, and snow depth. Data are available at hourly intervals by water year (1 October-30 September) in non-proprietary formats from online data repositories (https://doi.org/10.6071/M3S94T)

Translocator protein in late stage Alzheimer\u27s disease and Dementia with Lewy bodies brains

OBJECTIVE: Increased translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), in glial cells of the brain has been used as a neuroinflammation marker in the early and middle stages of neurodegenerative diseases, such as Alzheimer\u27s disease (AD) and Dementia with Lewy Bodies (DLB). In this study, we investigated the changes in TSPO density with respect to late stage AD and DLB. METHODS: TSPO density was measured in multiple regions of postmortem human brains in 20 different cases: seven late stage AD cases (Braak amyloid average: C; Braak tangle average: VI; Aged 74-88, mean: 83 ± 5 years), five DLB cases (Braak amyloid average: C; Braak tangle average: V; Aged 79-91, mean: 84 ± 4 years), and eight age-matched normal control cases (3 males, 5 females: aged 77-92 years; mean: 87 ± 6 years). Measurements were taken by quantitative autoradiography using [ RESULTS: No significant changes were found in TSPO density of the frontal cortex, striatum, thalamus, or red nucleus of the AD and DLB brains. A significant reduction in TSPO density was found in the substantia nigra (SN) of the AD and DLB brains compared to that of age-matched healthy controls. INTERPRETATION: This distinct pattern of TSPO density change in late stage AD and DLB cases may imply the occurrence of microglia dystrophy in late stage neurodegeneration. Furthermore, TSPO may not only be a microglia activation marker in early stage AD and DLB, but TSPO may also be used to monitor microglia dysfunction in the late stage of these diseases

Thermal Re-emission Model

Starting from a continuum description, we study the non-equilibrium roughening of a thermal re-emission model for etching in one and two spatial dimensions. Using standard analytical techniques, we map our problem to a generalized version of an earlier non-local KPZ (Kardar-Parisi-Zhang) model. In 2+1 dimensions, the values of the roughness and the dynamic exponents calculated from our theory go like $\alpha \approx z \approx 1$ and in 1+1 dimensions, the exponents resemble the KPZ values for low vapor pressure, supporting experimental results. Interestingly, Galilean invariance is maintained althrough.Comment: 4 pages, minor textual corrections and typos, accepted in Physical Review B (rapid