scholarly journals Rapid measurement of the local pressure amplitude in microchannel acoustophoresis using motile cells

2021 ◽  
Vol 150 (2) ◽  
pp. 1565-1576
Author(s):  
Minji Kim ◽  
Rune Barnkob ◽  
J. Mark Meacham
Keyword(s):  
Pressure Amplitude ◽  
Local Pressure ◽  
Rapid Measurement ◽  
Motile Cells

Measuring the local pressure amplitude in microchannel acoustophoresis

Lab on a Chip ◽  
2010 ◽  
Vol 10 (5) ◽  
pp. 563 ◽  
Author(s):  
Rune Barnkob ◽  
Per Augustsson ◽  
Thomas Laurell ◽  
Henrik Bruus
Keyword(s):  
Pressure Amplitude ◽  
Local Pressure

An Attack on the Contamination Problem in the Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 368-368
Author(s):  
J. J. Kelsch ◽  
A. Holtz
Keyword(s):  
Electron Microscope ◽  
Pressure Gradient ◽  
Ionization Potential ◽  
Simple Solution ◽  
Specimen Surface ◽  
Contamination Rate ◽  
Local Pressure ◽  
High Ionization ◽  
Hydrocarbon Molecules ◽  
Contamination Problem

A simple solution to the serious problem of specimen contamination in the electron microscope is presented. This is accomplished by the introduction of clean helium into the vacuum exactly at the specimen position. The local pressure gradient thus established inhibits the migration of hydrocarbon molecules to the specimen surface. The high ionization potential of He permits the use of relatively large volumes of the gas, without interfering with gun stability. The contamination rate is reduced on metal samples by a factor of 10.

Modulated polarization microscopy displays the dynamics of cytoskeletal structures in living, motile cells

1995 ◽  
Vol 53 ◽  
pp. 902-903
Author(s):  
J. R. Kuhn ◽  
M. Poenie
Keyword(s):  
Mitotic Spindle ◽  
Actin Filaments ◽  
Cell Shape ◽  
Dynamic Structure ◽  
Living Cells ◽  
Cytoskeletal Proteins ◽  
Polarization Microscopy ◽  
Video Enhancement ◽  
Ultrastructural Studies ◽  
Motile Cells

Cell shape and movement are controlled by elements of the cytoskeleton including actin filaments an microtubules. Unfortunately, it is difficult to visualize the cytoskeleton in living cells and hence follow it dynamics. Immunofluorescence and ultrastructural studies of fixed cells while providing clear images of the cytoskeleton, give only a static picture of this dynamic structure. Microinjection of fluorescently Is beled cytoskeletal proteins has proved useful as a way to follow some cytoskeletal events, but long terry studies are generally limited by the bleaching of fluorophores and presence of unassembled monomers.Polarization microscopy has the potential for visualizing the cytoskeleton. Although at present, it ha mainly been used for visualizing the mitotic spindle. Polarization microscopy is attractive in that it pro vides a way to selectively image structures such as cytoskeletal filaments that are birefringent. By combing ing standard polarization microscopy with video enhancement techniques it has been possible to image single filaments. In this case, however, filament intensity depends on the orientation of the polarizer and analyzer with respect to the specimen.

Use of backscattered electron image intensity signals to calculate the water/cement ratio of concrete

1992 ◽  
Vol 50 (1) ◽  
pp. 356-357
Author(s):  
R. J. Lee ◽  
A. J. Schwoeble ◽  
Yuan Jie
Keyword(s):  
Reliable Data ◽  
X Ray ◽  
Rapid Measurement ◽  
Trained Personnel ◽  
Electron Image ◽  
Backscattered Electron ◽  
Production Period ◽  
Strength And Durability ◽  
Automated Procedures ◽  
Standard Density

Water/Cement (W/C) ratio is a very important parameter affecting the strength and durability of concrete. At the present time, there are no ASTM methods for determining W/C ratio of concrete structures after the production period. Existing techniques involving thin section standard density comparative associations using light optical microscopy and rely on visual comparisons using standards and require highly trained personnel to produce reliable data. This has led to the exploration of other methods utilizing automated procedures which can offer a precise and rapid measurement of W/C ratio. This paper discusses methods of determining W/C ratio using a scanning electron microscope (SEM) backscattered electron image (BEI) intensity signal and x-ray computer tomography.

Healing venous ulcers with different modalities of leg compression

Phlebologie ◽  
2006 ◽  
Vol 35 (05) ◽  
pp. 349-355 ◽  
Author(s):  
E. O. Brizzio ◽  
G. Rossi ◽  
A. Chirinos ◽  
I. Cantero ◽  
G. Idiazabal ◽  
...  
Keyword(s):  
Wound Care ◽  
Univariate Analysis ◽  
Compression Therapy ◽  
Healing Time ◽  
Clinical Parameters ◽  
Compression Stockings ◽  
Local Pressure ◽  
Ulcer Size ◽  
Venous Ulcers ◽  
Unexpected Findings

Summary Background: Compression therapy (CT) is the stronghold of treatment of venous leg ulcers. We evaluated 5 modalities of CT in a prospective open pilot study using a unique trial design. Patients and methods: A group of experienced phlebologists assigned 31 consecutive patients with 35 venous ulcers (present for 2 to 24 months with no prior CT) to 5 different modalities of leg compression, 7 ulcers to each group. The challenge was to match the modality of CT with the features of the ulcer in order to achieve as many healings as possible. Wound care used standard techniques and specifically tailored foam pads to increase local pressure. CT modalities were either stockings Sigvaris® 15-20, 20-30, 30-40 mmHg, multi-layer bandages, or CircAid® bandaging. Compression was maintained day and night in all groups and changed at weekly visits. Study endpoints were time to healing and the clinical parameters predicting the outcome. Results: The cumulative healing rates were 71%, 77%, and 83% after 3, 6, and 9 months, respectively. Univariate analysis of variables associated with nonhealing were: previous surgery, presence of insufficient perforating and/or deep veins, older age, recurrence, amount of oedema, time of presence of CVI and the actual ulcer, and ulcer size (p <0.05-<0.001). The initial ulcer size was the best predictor of the healing-time (Pearson r=0.55, p=0.002). The modality of CT played an important role also, as 19 of 21 ulcers (90%) healed with stockings but only 8 of 14 with bandages (57%; p=0.021). Regression analysis allowed to calculate a model to predict the healing time. It compensated for the fact that patients treated with low or moderate compression stockings were at lower risk of non-healing. and revealed that healing with stockings was about twice as rapid as healing with bandages. Conclusion: Three fourths of venous ulcers can be brought to healing within 3 to 6 months. Healing time can be predicted using easy to assess clinical parameters. Irrespective of the initial presentation ulcer healing appeared more rapid with the application of stockings than with bandaging. These unexpected findings contradict current believes and require confirmation in randomised trials.

Nonlinear dynamics of a shell encapsulated microbubble near solid boundary in an ultrasonic field

2020 ◽  
Vol 14 (3) ◽  
pp. 7235-7243
Author(s):  
N.M. Ali ◽  
F. Dzaharudin ◽  
E.A. Alias
Keyword(s):  
Oscillation Amplitude ◽  
Ultrasonic Field ◽  
Dynamical Behaviour ◽  
Ultrasound Contrast Agents ◽  
Chaotic Behaviour ◽  
Solid Boundary ◽  
Driving Frequency ◽  
Pressure Amplitude ◽  
Radial Expansion ◽  
Therapeutic Delivery

Microbubbles have the potential to be used for diagnostic imaging and therapeutic delivery. However, the transition from microbubbles currently being used as ultrasound contrast agents to achieve its’ potentials in the biomedical field requires more in depth understanding. Of particular importance is the influence of microbubble encapsulation of a microbubble near a vessel wall on the dynamical behaviour as it stabilizes the bubble. However, many bubble studies do not consider shell encapsulation in their studies. In this work, the dynamics of an encapsulated microbubble near a boundary was studied by numerically solving the governing equations for microbubble oscillation. In order to elucidate the effects of a boundary to the non-linear microbubble oscillation the separation distances between microbubble will be varied along with the acoustic driving. The complex nonlinear vibration response was studied in terms of bifurcation diagrams and the maximum radial expansion. It was found that the increase in distance between the boundary and the encapsulated bubble will increase the oscillation amplitude. When the value of pressure amplitude increased the single bubble is more likely to exhibit the chaotic behaviour and maximum radius also increase as the inter wall-bubble distance is gradually increased. While, with higher driving frequency the maximum radial expansion decreases and suppress the chaotic behaviour.

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