Electron Beam-Induced Carbon Erosion and the Impact on Electron Probe Microanalysis

AbstractElectron beam-induced carbon contamination is a balance between simultaneous deposition and erosion processes. Net erosion rates for a 25 nA 3 kV beam can reduce a 5 nm C coating by 20% in 60 s. Measurements were made on C-coated Bi substrates, with coating thicknesses of 5–20 nm, over a range of analysis conditions. Erosion showed a step-like increase with increasing electron flux density. Both the erosion rate and its rate of change increase with decreasing accelerating voltage. As the flux density decreases the rate of change increases more rapidly with decreasing voltage. Time-dependent intensity (TDI) measurements can be used to correct for errors, in both coating and substrate quantifications, resulting from carbon erosion. Uncorrected analyses showed increasing errors in coating thickness with decreasing accelerating voltage. Although the erosion rate was found to be independent of coating thickness this produces an increasing absolute error with decreasing starting thickness, ranging from 1.5% for a 20 nm C coating on Bi at 15 kV to 14% for a 5 nm coating at 3 kV. Errors in Bi Mα measurement are <1% at 5 kV or above but increase rapidly below this, both with decreasing voltage and increasing coating thickness to 20% for a 20 nm coated sample at 3 kV.

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QUANTIFYING THE IMPACT OF VEGETATION ON EROSION PROCESSES ALONG THE NIAGARA ESCARPMENT IN THE HAMILTON REGION OF SOUTHERN ONTARIO

10.1130/abs/2020am-357459 ◽

2020 ◽

Author(s):

Allie J. Ellis ◽

◽

Carolyn H. Eyles ◽

Carolyn H. Eyles

Keyword(s):

Southern Ontario ◽

Niagara Escarpment ◽

Erosion Processes ◽

The Impact

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Expanding 3D Nanoprinting Performance by Blurring the Electron Beam

Micromachines ◽

10.3390/mi12020115 ◽

2021 ◽

Vol 12 (2) ◽

pp. 115

Author(s):

Lukas Seewald ◽

Robert Winkler ◽

Gerald Kothleitner ◽

Harald Plank

Keyword(s):

Electron Beam ◽

Direct Write ◽

Design Flexibility ◽

Individual Branch ◽

Inclination Angles ◽

3D Architecture ◽

20 Nm ◽

Surface Morphologies ◽

Nm Range ◽

Mechanical Rigidity

Additive, direct-write manufacturing via a focused electron beam has evolved into a reliable 3D nanoprinting technology in recent years. Aside from low demands on substrate materials and surface morphologies, this technology allows the fabrication of freestanding, 3D architectures with feature sizes down to the sub-20 nm range. While indispensably needed for some concepts (e.g., 3D nano-plasmonics), the final applications can also be limited due to low mechanical rigidity, and thermal- or electric conductivities. To optimize these properties, without changing the overall 3D architecture, a controlled method for tuning individual branch diameters is desirable. Following this motivation, here, we introduce on-purpose beam blurring for controlled upward scaling and study the behavior at different inclination angles. The study reveals a massive boost in growth efficiencies up to a factor of five and the strong delay of unwanted proximal growth. In doing so, this work expands the design flexibility of this technology.

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Effects of Sex and Physical Activity Level on Serum Biomarker-Based Physiological Dysregulation: The Impact to Predict Frailty and Mortality in the Quebec NuAge Cohort

Gerontology ◽

10.1159/000514169 ◽

2021 ◽

pp. 1-14

Author(s):

Ahmed Ghachem ◽

Frédérik Dufour ◽

Tamas Fülöp ◽

Pierrette Gaudreau ◽

Alan A. Cohen

Keyword(s):

Physical Activity ◽

Older Adults ◽

Kidney Function ◽

Oxygen Transport ◽

Physical Activity Level ◽

Rate Of Change ◽

Activity Level ◽

Men And Women ◽

Physiological Dysregulation ◽

The Impact

Background: Age-related changes in biological processes such as physiological dysregulation (the progressive loss of homeostatic capacity) vary considerably among older adults and may influence health profiles in late life. These differences could be related, at least in part, to the impact of intrinsic and extrinsic factors such as sex and physical activity level (PAL). Objectives: The objectives of this study were (1) to assess the magnitude and rate of changes in physiological dysregulation in men and women according to PAL and (2) to determine whether/how sex and PAL mediate the apparent influence of physiological dysregulation on health outcomes (frailty and mortality). Methods: We used data on 1,754 community-dwelling older adults (age = 74.4 ± 4.2 years; women = 52.4%) of the Quebec NuAge cohort study. Physiological dysregulation was calculated based on Mahalanobis distance of 31 biomarkers regrouped into 5 systems: oxygen transport, liver/kidney function, leukopoiesis, micronutrients, and lipids. Results: As expected, mean physiological dysregulation significantly increased with age while PAL decreased. For the same age and PAL, men showed higher levels of physiological dysregulation globally in 3 systems: oxygen transport, liver/kidney function, and leukopoiesis. Men also showed faster global physiological dysregulation in the liver/kidney and leukopoiesis systems. Overall, high PAL was associated with lower level and slower rate of change of physiological dysregulation. Finally, while mortality and frailty risk significantly increased with physiological dysregulation, there was no evidence for differences in these effects between sexes and PAL. Conclusion: Our results showed that both sex and PAL have a significant effect on physiological dysregulation levels and rates of change. Also, although a higher PAL was associated with lower level and slower rate of change of physiological dysregulation, there was no evidence that PAL attenuates the effect of physiological dysregulation on subsequent declines in health at the end of life. Substantial work remains to understand how modifiable behaviors impact the relationship between physiological dysregulation, frailty, and mortality in men and women.

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Independent and combined impact of hypoxia and acute inorganic nitrate ingestion on thermoregulatory responses to the cold

European Journal of Applied Physiology ◽

10.1007/s00421-021-04602-x ◽

2021 ◽

Vol 121 (4) ◽

pp. 1207-1218

Author(s):

Josh T. Arnold ◽

Stephen J. Bailey ◽

Simon G. Hodder ◽

Naoto Fujii ◽

Alex B. Lloyd

Keyword(s):

Blood Flow ◽

Cooling Rate ◽

Skin Blood Flow ◽

Rectal Temperature ◽

Onset Time ◽

Rate Of Change ◽

Vascular Control ◽

Delta Change ◽

Core Cooling ◽

The Impact

Abstract Purpose This study assessed the impact of normobaric hypoxia and acute nitrate ingestion on shivering thermogenesis, cutaneous vascular control, and thermometrics in response to cold stress. Method Eleven male volunteers underwent passive cooling at 10 °C air temperature across four conditions: (1) normoxia with placebo ingestion, (2) hypoxia (0.130 FiO2) with placebo ingestion, (3) normoxia with 13 mmol nitrate ingestion, and (4) hypoxia with nitrate ingestion. Physiological metrics were assessed as a rate of change over 45 min to determine heat loss, and at the point of shivering onset to determine the thermogenic thermoeffector threshold. Result Independently, hypoxia expedited shivering onset time (p = 0.05) due to a faster cooling rate as opposed to a change in central thermoeffector thresholds. Specifically, compared to normoxia, hypoxia increased skin blood flow (p = 0.02), leading to an increased core-cooling rate (p = 0.04) and delta change in rectal temperature (p = 0.03) over 45 min, yet the same rectal temperature at shivering onset (p = 0.9). Independently, nitrate ingestion delayed shivering onset time (p = 0.01), mediated by a change in central thermoeffector thresholds, independent of changes in peripheral heat exchange. Specifically, compared to placebo ingestion, no difference was observed in skin blood flow (p = 0.5), core-cooling rate (p = 0.5), or delta change in rectal temperature (p = 0.7) over 45 min, while nitrate reduced rectal temperature at shivering onset (p = 0.04). No interaction was observed between hypoxia and nitrate ingestion. Conclusion These data improve our understanding of how hypoxia and nitric oxide modulate cold thermoregulation.

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Systematic Studies of Fullerene Derivative Electron Beam Resists

MRS Proceedings ◽

10.1557/proc-584-115 ◽

1999 ◽

Vol 584 ◽

Author(s):

A. P. G. Robinson ◽

R. E. Palmer ◽

T. Tada ◽

T. Kanayama ◽

E. J. Shelley ◽

...

Keyword(s):

Electron Beam ◽

Dissolution Rate ◽

Organic Solvents ◽

Spin Coating ◽

Electron Beam Irradiation ◽

Fullerene Derivative ◽

Silicon Substrates ◽

Beam Irradiation ◽

Negative Tone ◽

20 Nm

AbstractWe report systematic studies of the response of C60 derivatives to electron beam irradiation. Films of fourteen different mono, tris and tetra adduct methanofullerene C60 derivatives were produced by spin coating on hydrogen terminated silicon substrates. Exposure of the films to a 20 keV electron beam substantially altered the dissolution rate of the derivative films in organic solvents such as monochlorobenzene. All of the derivatives exhibited negative tone resist behaviour with sensitivities between ∼ 8.5 × 10-4 and ∼ 4 × 10-3 C/cm2 107, much higher than that of C60. Features with widths of ∼ 20 nm were produced using these compounds, and the etch ratios of the compounds were found to be more than twice those of a standard novolac based resist (SAL601).

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Temperature Dependent Photoluminescence of ZnSe/Alq3 Hybrid Heterostructure

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.55-57.493 ◽

2008 ◽

Vol 55-57 ◽

pp. 493-496

Author(s):

Wisanu Pecharapa ◽

P. Potirak ◽

W. Yindeesuk

Keyword(s):

Electron Beam ◽

Quantum Efficiency ◽

Exciton State ◽

Temperature Dependent ◽

Pl Spectra ◽

20 Nm ◽

Temperature Dependent Photoluminescence

II-VI inorganic/organic heterostructures consisting of ZnSe and tris(8-hydroxyquinoline) aluminum (Alq3) were prepared by electron beam evaporator. Alq3 layer with 20 nm was grown between 200-nm ZnSe layers. Photoluminescence measurement was conducted at various temperatures in order to investigate the important temperature-dependent parameters of this structure. PL spectra revealed thermal population of exciton state and the change in PL quantum efficiency of the film.

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A multi-decade assessment of the impact of large fire events on sediment redistribution using LAPSUS - the Águeda catchment, north-central Portugal

10.5194/egusphere-egu21-4615 ◽

2021 ◽

Author(s):

Dante Föllmi ◽

Jantiene Baartman ◽

João Pedro Nunes ◽

Akli Benali

Keyword(s):

Soil Depth ◽

Spatial Scales ◽

Fire Severity ◽

Sediment Dynamics ◽

Land Uses ◽

Erosion Rates ◽

Erosion Processes ◽

Sediment Redistribution ◽

Central Portugal ◽

The Impact

AbstractWildfires have become an increasing threat for Mediterranean ecosystems, due to increasing climate change induced wildfire activity and changing land management practices. Apart from the initial risk, fire can alter the soil in various ways depending on different fire severities and thus post-fire erosion processes are an important component in assessing wildfires&#8217; negative effects. Recent post-fire erosion (modelling) studies often focus on a short time window and lack the attention for sediment dynamics at larger spatial scales. Yet, these large spatial and temporal scales are fundamental for a better understanding of catchment sediment dynamics and long-term destructive effects of multiple fires on post-fire erosion processes. In this study the landscape evolution model LAPSUS was used to simulate erosion and deposition in the 404 km2 &#193;gueda catchment in northern-central Portugal over a 41 year (1979-2020) timespan. To include variation in fire severity and its impact on the soil four burnt severity classes, represented by the difference Normalized Burn Ratio (dNBR), were parameterized. Although model calibration was difficult due to lack of spatial and temporal measured data, the results show that average post-fire net erosion rates were significantly higher in the wildfire scenarios (5.95 ton ha-1 yr-1) compared to those of a non-wildfire scenario (0.58 ton ha-1 yr-1). Furthermore, erosion values increased with a higher level of burnt severity and multiple fires increased the overall sediment build-up in the catchment, fostering an increase in background sediment yield. Simulated erosion patterns showed great spatial variability with large deposition and erosion rates inside streams. Due to this variability, it was difficult to identify land uses that were most sensitive for post-fire erosion, because some land-uses were located in more erosion-sensitive areas (e.g. streams, gullies) or were more affected by high burnt severity levels than others. Despite these limitations, LAPSUS performed well on addressing spatial sediment processes and has the ability to contribute to pre-fire management strategies. For instance, the percentage soil loss map (i.e. comparison of erosion and soil depth maps) could identify locations at risk.

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Effect of powder oxidation on the impact toughness of electron beam melting Ti-6Al-4V

Additive Manufacturing ◽

10.1016/j.addma.2017.08.002 ◽

2017 ◽

Vol 17 ◽

pp. 123-134 ◽

Cited By ~ 10

Author(s):

W.A. Grell ◽

E. Solis-Ramos ◽

E. Clark ◽

E. Lucon ◽

E.J. Garboczi ◽

...

Keyword(s):

Electron Beam ◽

Impact Toughness ◽

Electron Beam Melting ◽

The Impact

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Influence of Polyurea Composite Coating on Selected Mechanical Properties of AISI 304 Steel

Materials ◽

10.3390/ma12193137 ◽

2019 ◽

Vol 12 (19) ◽

pp. 3137 ◽

Cited By ~ 3

Author(s):

Monika Duda ◽

Joanna Pach ◽

Grzegorz Lesiuk

Keyword(s):

Mechanical Properties ◽

Epoxy Resin ◽

Composite Coating ◽

Composite Coatings ◽

Glass Fabric ◽

Coated Sample ◽

Hemp Fiber ◽

Aisi 304 ◽

Aisi 304 Steel ◽

The Impact

This paper contains experimental results of mechanical testing of the AISI 304 steel with composite coatings. The main goal was to investigate the impact of the applied polyurea composite coating on selected mechanical properties: Adhesion, impact resistance, static behavior, and, finally, fatigue lifetime of notched specimens. In the paper the following configurations of coatings were tested: EP (epoxy resin), EP_GF (epoxy resin + glass fabric), EP_GF_HF (epoxy resin + glass fabric hemp fiber), EP_PUA (epoxy resin + polyurea) resin, EP_GF_PUA (epoxy resin + glass fabric + polyurea) resin, and EP_GF_HF_PUA (epoxy resin + glass fabric + hemp fiber + polyurea) resin. The highest value of force required to break adhesive bonds was observed for the EP_PUA coating, the smallest for the single EP coating. A tendency of polyurea to increase the adhesion of the coating to the base was noticed. The largest area of delamination during the impact test was observed for the EP_GF_HF coating and the smallest for the EP-coated sample. In all tested samples, observed delamination damage during the pull-off test was located between the coating and the metallic base of the sample.

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