A constant-speed penetrometer for high-resolution snow stratigraphy

A new constant-speed penetrometer for field and laboratory measurement has been developed. The initially independent work of SFISAR and CRREL has been brought together, and a portable field device is now in an advanced stage of testing. The new penetrometer has high rigidity and a high-resolution large dynamic range force sensor. It uses a much smaller sensing head (5 mm) than previous designs and has a constant-speed drive. With this construction, the penetration resistance of very fine layers and the influence of the bonding strength between snow grains can be more accurately determined than is possible with the rammsonde or Pandalp. Artificial foam layers as thin as 2 mm and thin layers in snow have been detected by the penetrometer. Thin snow layers detected from penetration-resistance profiles have been correlated to fine layering as determined from plane-section microphotographs of samples taken adjacent to the profile. The instrument’s measurements are highly repeatable and the lack of subjective decisions when operating the penetrometer makes the penetration resistance a quantitative measure of snow stratigraphy.

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Slow-scan CCD cameras and low-dose High-Resolution Electron Microscopy: Direct and quantitative

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100169791 ◽

1994 ◽

Vol 52 ◽

pp. 412-413

Author(s):

M. Pan

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Structural Damage ◽

Low Dose ◽

Dynamic Range ◽

High Resolution Electron Microscopy ◽

Operating Conditions ◽

Digital Data ◽

Ccd Cameras ◽

Resolution Electron

It has been known for many years that materials such as zeolites, polymers, and biological specimens have crystalline structures that are vulnerable to electron beam irradiation. This radiation damage severely restrains the use of high resolution electron microscopy (HREM). As a result, structural characterization of these materials using HREM techniques becomes difficult and challenging. The emergence of slow-scan CCD cameras in recent years has made it possible to record high resolution (∽2Å) structural images with low beam intensity before any apparent structural damage occurs. Among the many ideal properties of slow-scan CCD cameras, the low readout noise and digital recording allow for low-dose HREM to be carried out in an efficient and quantitative way. For example, the image quality (or resolution) can be readily evaluated on-line at the microscope and this information can then be used to optimize the operating conditions, thus ensuring that high quality images are recorded. Since slow-scan CCD cameras output (undistorted) digital data within the large dynamic range (103-104), they are ideal for quantitative electron diffraction and microscopy.

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Revealing Inflammatory Indications Induced by Titanium Alloy Wear Debris in Periprosthetic Tissue by Label-Free Correlative High-Resolution Ion, Electron and Optical Microspectroscopy

Materials ◽

10.3390/ma14113048 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3048

Author(s):

Rok Podlipec ◽

Esther Punzón-Quijorna ◽

Luka Pirker ◽

Mitja Kelemen ◽

Primož Vavpetič ◽

...

Keyword(s):

Titanium Alloy ◽

High Resolution ◽

Wear Debris ◽

Ion Beam ◽

Quantitative Measure ◽

Label Free ◽

Periprosthetic Tissue ◽

Correlative Microscopy ◽

X Ray ◽

Tissue Reactions

The metallic-associated adverse local tissue reactions (ALTR) and events accompanying worn-broken implant materials are still poorly understood on the subcellular and molecular level. Current immunohistochemical techniques lack spatial resolution and chemical sensitivity to investigate causal relations between material and biological response on submicron and even nanoscale. In our study, new insights of titanium alloy debris-tissue interaction were revealed by the implementation of label-free high-resolution correlative microscopy approaches. We have successfully characterized its chemical and biological impact on the periprosthetic tissue obtained at revision surgery of a fractured titanium-alloy modular neck of a patient with hip osteoarthritis. We applied a combination of photon, electron and ion beam micro-spectroscopy techniques, including hybrid optical fluorescence and reflectance micro-spectroscopy, scanning electron microscopy (SEM), Energy-dispersive X-ray Spectroscopy (EDS), helium ion microscopy (HIM) and micro-particle-induced X-ray emission (micro-PIXE). Micron-sized wear debris were found as the main cause of the tissue oxidative stress exhibited through lipopigments accumulation in the nearby lysosome. This may explain the indications of chronic inflammation from prior histologic examination. Furthermore, insights on extensive fretting and corrosion of the debris on nm scale and a quantitative measure of significant Al and V release into the tissue together with hydroxyapatite-like layer formation particularly bound to the regions with the highest Al content were revealed. The functional and structural information obtained at molecular and subcellular level contributes to a better understanding of the macroscopic inflammatory processes observed in the tissue level. The established label-free correlative microscopy approach can efficiently be adopted to study any other clinical cases related to ALTR.

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High-resolution VLA low radio frequency observations of the Perseus cluster: radio lobes, mini-halo, and bent-jet radio galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2003 ◽

2020 ◽

Vol 499 (4) ◽

pp. 5791-5805

Author(s):

M Gendron-Marsolais ◽

J Hlavacek-Larrondo ◽

R J van Weeren ◽

L Rudnick ◽

T E Clarke ◽

...

Keyword(s):

High Resolution ◽

Dynamic Range ◽

Galaxy Cluster ◽

High Dynamic Range ◽

Radio Galaxies ◽

Radio Sources ◽

Nearby Galaxy ◽

Cluster Galaxy ◽

Ngc 1275 ◽

Perseus Cluster

ABSTRACT We present the first high-resolution 230–470 MHz map of the Perseus cluster obtained with the Karl G. Jansky Very Large Array. The high dynamic range and resolution achieved have allowed the identification of previously unknown structures in this nearby galaxy cluster. New hints of sub-structures appear in the inner radio lobes of the brightest cluster galaxy NGC 1275. The spurs of radio emission extending into the outer X-ray cavities, inflated by past nuclear outbursts, are seen for the first time at these frequencies, consistent with spectral aging. Beyond NGC 1275, we also analyse complex radio sources harboured in the cluster. Two new distinct, narrowly collimated jets are visible in IC 310, consistent with a highly projected narrow-angle tail radio galaxy infalling into the cluster. We show how this is in agreement with its blazar-like behaviour, implying that blazars and bent-jet radio galaxies are not mutually exclusive. We report the presence of filamentary structures across the entire tail of NGC 1265, including two new pairs of long filaments in the faintest bent extension of the tail. Such filaments have been seen in other cluster radio sources such as relics and radio lobes, indicating that there may be a fundamental connection between all these radio structures. We resolve the very narrow and straight tail of CR 15 without indication of double jets, so that the interpretation of such head–tail sources is yet unclear. Finally, we note that only the brightest western parts of the mini-halo remain, near NGC 1272 and its bent double jets.

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Measurement of synchrotron-radiation-excited Kossel patterns

Journal of Synchrotron Radiation ◽

10.1107/s1600577515019037 ◽

2016 ◽

Vol 23 (1) ◽

pp. 214-218 ◽

Cited By ~ 5

Author(s):

G. Bortel ◽

G. Faigel ◽

M. Tegze ◽

A. Chumakov

Keyword(s):

High Resolution ◽

Dynamic Range ◽

Structural Information ◽

Photon Counting ◽

Spot Size ◽

Low Noise ◽

X Rays ◽

Technical Problems ◽

Pixel Detectors ◽

Exciting Beam

Kossel line patterns contain information on the crystalline structure, such as the magnitude and the phase of Bragg reflections. For technical reasons, most of these patterns are obtained using electron beam excitation, which leads to surface sensitivity that limits the spatial extent of the structural information. To obtain the atomic structure in bulk volumes, X-rays should be used as the excitation radiation. However, there are technical problems, such as the need for high resolution, low noise, large dynamic range, photon counting, two-dimensional pixel detectors and the small spot size of the exciting beam, which have prevented the widespread use of Kossel pattern analysis. Here, an experimental setup is described, which can be used for the measurement of Kossel patterns in a reasonable time and with high resolution to recover structural information.

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High-resolution and large dynamic range fiber extrinsic Fabry–Perot sensing by multi-extrema-tracing technique

Applied Optics ◽

10.1364/ao.54.003677 ◽

2015 ◽

Vol 54 (12) ◽

pp. 3677 ◽

Cited By ~ 1

Author(s):

Jiawei Mei ◽

Xiaosheng Xiao ◽

Changxi Yang

Keyword(s):

High Resolution ◽

Dynamic Range ◽

Large Dynamic Range ◽

Fabry Perot

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Ion-implantation Generated Nanovoids in Si and MgO Monitored by High Resolution Positron Beam Analysis

MRS Proceedings ◽

10.1557/proc-647-o14.11/r9.11 ◽

2000 ◽

Vol 647 ◽

Cited By ~ 3

Author(s):

S.W.H. Eijt ◽

C.V. Falub ◽

A. van Veen ◽

H. Schut ◽

P.E. Mijnarends ◽

...

Keyword(s):

High Resolution ◽

Ion Implantation ◽

Average Energy ◽

Internal Surface ◽

Positron Beam ◽

Initial Energy ◽

Thin Layers ◽

Beam Analysis ◽

Width Reduction ◽

Non Destructive

AbstractThe formation of nanovoids in Si(100) and MgO(100) by 3He ion implantation has been studied. Contrary to Si in which the voids are generally almost spherical, in MgO nearly perfectly rectangular nanosize voids are created. Recently, the 2D-ACAR setup at the Delft Positron Research Center has been coupled to the intense reactor-based variable-energy positron beam POSH. This allows a new method of monitoring thin layers containing nanovoids or defects by depth-selective high-resolution positron beam analysis. The 2D-ACAR spectra of Si with a buried layer of nanocavities reveal the presence of two additional components, the first related to para-positronium (p-Ps) formation in the nanovoids, and a second one most likely related to unsaturated Si-bonds at the internal surface of the voids. The positronium is present in excited kinetic states with an average energy of 0.3 eV. Refilling of the cavities by means of low dose 3He implantation (1×1014 cm−2) followed by annealing reduces the formation of Ps and the width of the Ps peak in the ACAR spectrum. This width reduction is due to collisions of Ps with He atoms in the voids. In MgO, p-Ps formed with an initial energy of ~3 eV shows a final average energy of 1.6 eV at annihilation due to collisions with the cavity walls. Possibilities of this new, non-destructive method of monitoring the sizes of cavities and the evolution of nanovoid layers will be discussed.

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High-Resolution Bioprinting of Recombinant Human Collagen Type III

Polymers ◽

10.3390/polym13172973 ◽

2021 ◽

Vol 13 (17) ◽

pp. 2973

Author(s):

Rory Gibney ◽

Jennifer Patterson ◽

Eleonora Ferraris

Keyword(s):

Tissue Engineering ◽

High Resolution ◽

Collagen Type ◽

Thin Layers ◽

Corneal Tissue ◽

Collagen Type Iii ◽

Type Iii ◽

Pure Collagen ◽

Human Collagen ◽

Visible Wavelengths

The development of commercial collagen inks for extrusion-based bioprinting has increased the amount of research on pure collagen bioprinting, i.e., collagen inks not mixed with gelatin, alginate, or other more common biomaterial inks. New printing techniques have also improved the resolution achievable with pure collagen bioprinting. However, the resultant collagen constructs still appear too weak to replicate dense collagenous tissues, such as the cornea. This work aims to demonstrate the first reported case of bioprinted recombinant collagen films with suitable optical and mechanical properties for corneal tissue engineering. The printing technology used, aerosol jet® printing (AJP), is a high-resolution printing method normally used to deposit conductive inks for electronic printing. In this work, AJP was employed to deposit recombinant human collagen type III (RHCIII) in overlapping continuous lines of 60 µm to form thin layers. Layers were repeated up to 764 times to result in a construct that was considered a few hundred microns thick when swollen. Samples were subsequently neutralised and crosslinked using EDC:NHS crosslinking. Nanoindentation and absorbance measurements were conducted, and the results show that the AJP-deposited RHCIII samples possess suitable mechanical and optical properties for corneal tissue engineering: an average effective elastic modulus of 506 ± 173 kPa and transparency ≥87% at all visible wavelengths. Circular dichroism showed that there was some loss of helicity of the collagen due to aerosolisation. SDS-PAGE and pepsin digestion were used to show that while some collagen is degraded due to aerosolisation, it remains an inaccessible substrate for pepsin cleavage.

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