scholarly journals Microfluidic resonators with two parallel channels for independent sample loading and effective density tuning

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Jungchul Lee ◽  
Faheem Khan ◽  
Thomas Thundat ◽  
Bong Jae Lee
Keyword(s):  
Silicon Nitride ◽  
Potassium Hydroxide ◽  
Laser Doppler Vibrometer ◽  
Effective Density ◽  
Fluidic Channel ◽  
Custom Made ◽  
Sample Density ◽  
Polysilicon Layer ◽  
Parallel Channels ◽  
First Time

ABSTRACTThis paper reports doubly clamped microchannel embedded resonators with two independent and parallel channels integrated for effective sample density tuning for the first time. With the aid of such a unique design, each fluidic channel can be independently accessed thus different liquid samples can be loaded simultaneously. The proposed fluidic resonators are batch fabricated by depositing silicon nitride, polysilicon, and silicon nitride sequentially on top of a set of 4-inch silicon wafers and sacrificing the middle polysilicon layer with potassium hydroxide (KOH). The sacrificial process defines two parallel channels and releases doubly clamped beam resonators simultaneously. In addition, an off-chip vacuum clamp with optical and fluidic access is custom-made to operate each resonator with enhanced quality factor. The microfluidic resonators mounted on the custom vacuum clamp are thoroughly characterized with a laser Doppler vibrometer and used to measure the effective sample density ranging from 395 to 998 kg/m3.

scholarly journals Extra-gastric expression of the proton pump H+/K+-ATPase in the gills and kidney of the teleost Oreochromis niloticus

2020 ◽  
Vol 223 (16) ◽  
pp. jeb214890
Author(s):  
Ebtesam Ali Barnawi ◽  
Justine E. Doherty ◽  
Patrícia Gomes Ferreira ◽  
Jonathan M. Wilson
Keyword(s):  
Oreochromis Niloticus ◽  
Cellular Localization ◽  
Ex Vivo ◽  
Uptake Inhibition ◽  
Custom Made ◽  
Potassium Regulation ◽  
Immunohistochemical Techniques ◽  
Collecting Tubules ◽  
First Time

ABSTRACTPotassium regulation is essential for the proper functioning of excitable tissues in vertebrates. The H+/K+-ATPase (HKA), which is composed of the HKα1 (gene: atp4a) and HKβ (gene: atp4b) subunits, has an established role in potassium and acid–base regulation in mammals and is well known for its role in gastric acidification. However, the role of HKA in extra-gastric organs such as the gill and kidney is less clear, especially in fishes. In the present study in Nile tilapia, Oreochromis niloticus, uptake of the K+ surrogate flux marker rubidium (Rb+) was demonstrated in vivo; however, this uptake was not inhibited with omeprazole, a potent inhibitor of the gastric HKA. This contrasts with gill and kidney ex vivo preparations, where tissue Rb+ uptake was significantly inhibited by omeprazole and SCH28080, another gastric HKA inhibitor. The cellular localization of this pump in both the gill and kidney was demonstrated using immunohistochemical techniques with custom-made antibodies specific for Atp4a and Atp4b. Antibodies against the two subunits showed the same apical ionocyte distribution pattern in the gill and collecting tubules/ducts in the kidney. Atp4a antibody specificity was confirmed by western blotting. RT-PCT was used to confirm the expression of both subunits in the gill and kidney. Taken together, these results indicate for the first time K+ (Rb+) uptake in O. niloticus and that HKA is implicated, as shown through the ex vivo uptake inhibition by omeprazole and SCH28080, verifying a role for HKA in K+ absorption in the gill's ionocytes and collecting tubule/duct segments of the kidney.

scholarly journals Dense, Strong, and Precise Silicon Nitride-Based Ceramic Parts by Lithography-Based Ceramic Manufacturing

2020 ◽  
Vol 10 (3) ◽  
pp. 996 ◽  
Author(s):  
Altan Alpay Altun ◽  
Thomas Prochaska ◽  
Thomas Konegger ◽  
Martin Schwentenwein
Keyword(s):  
Surface Roughness ◽  
High Temperature ◽  
Light Scattering ◽  
Silicon Nitride ◽  
Material Properties ◽  
Refractive Indices ◽  
High Relative Density ◽  
Ceramic Manufacturing ◽  
High Level ◽  
First Time

Due to the high level of light absorption and light scattering of dark colored powders connected with the high refractive indices of ceramic particles, the majority of ceramics studied via stereolithography (SLA) have been light in color, including ceramics such as alumina, zirconia and tricalcium phosphate. This article focuses on a lithography-based ceramic manufacturing (LCM) method for β-SiAlON ceramics that are derived from silicon nitride and have excellent material properties for high temperature applications. This study demonstrates the general feasibility of manufacturing of silicon nitride-based ceramic parts by LCM for the first time and combines the advantages of SLA, such as the achievable complexity and low surface roughness (Ra = 0.50 µm), with the typical properties of conventionally manufactured silicon nitride-based ceramics, such as high relative density (99.8%), biaxial strength (σf = 764 MPa), and hardness (HV10 = 1500).

Temperature and frequency dependencies of the effective density of surface states at silicon-silicon nitride interface

1970 ◽  
Vol 13 (7) ◽  
pp. 1097-1101 ◽  
Author(s):  
Š. Luby ◽  
R.N. Lovjagin ◽  
N. Doshdikova ◽  
L.N. Alexandrov ◽  
J. Červenãk
Keyword(s):  
Silicon Nitride ◽  
Surface States ◽  
Effective Density ◽  
Silicon Silicon

Novel Fabrication and Characterization of Diaphragm Micromirror Using ‘Bulk Lithography’

2012 ◽  
Author(s):  
Prasanna Gandhi ◽  
Shital Kamble ◽  
Kiran Bhole
Keyword(s):  
Adaptive Optics ◽  
Focal Length ◽  
Laser Doppler Vibrometer ◽  
Single Layer ◽  
Layer By Layer ◽  
Micro Fabrication ◽  
Wavefront Correction ◽  
Fabrication And Characterization ◽  
First Time

Adaptive optics is being explored actively for several applications such as wavefront correction in biomedical imaging (retinal surgery), variable focal length lenses, and adaptive zoom micromirrors. Diaphragm micromirrors have several advantages such as continuity in image and ease of fabrication. This paper investigates, for the first time to the best of our knowledge, fabrication of diaphragm micromirror using a recently proposed novel process of ‘Bulk Lithography’. In contrast to classical microstereolithography (MSL) processes of 3D layer-by-layer micro fabrication, bulk lithography fabrication is done by scanning of laser beam over the photopolymer resin of unconstraint depth in a single layer scan. The process has capability to fabricate smoothly varying thickness diaphragms for micromirrors. However, as a first step, this paper demonstrates fabrication of uniform thickness micromirrors coated with aluminum. Micromirrors are fabricated with air trapped beneath them which contributes to enhanced stiffness and low damping. Further fabricated micromirror is characterized using laser doppler vibrometer.

Hydraulics of backflushing for efficiently cleaning hydropower trash racks

2014 ◽  
Vol 41 (3) ◽  
pp. 263-269 ◽  
Author(s):  
Hanne Nøvik ◽  
Leif Lia ◽  
Bjørnar Rettedal ◽  
Lars Eid Nielsen
Keyword(s):  
Pressure Difference ◽  
Small Hydropower ◽  
Measuring Device ◽  
Hydropower Plants ◽  
Custom Made ◽  
Large Measurement ◽  
Efficient Alternative ◽  
Approach Velocity ◽  
First Time

Backflushing is an efficient alternative for cleaning trash racks at small hydropower plants. The actual debris to trash rack adhesion is measured in situ for the first time by an innovative, custom-made measuring device. Despite large measurement variations caused by unevenness in debris distribution, the adhesion to trash rack for most types of debris and for most sites is relatively modest. There is also a trend where a higher maximum head loss through the trash rack increases the debris adhesion to the trash rack. The hydraulics around the trash rack during a backflushing process is assessed by monitoring the velocity development and the pressure difference through the trash rack in a physical model. As expected, when debris adhesion to the trash rack is high, releasing the attached debris requires a higher pressure difference through the trash rack and a higher approach velocity.

Investigations on Thermal Spraying of Silicon Nitride-Based Powders

1998 ◽  
Author(s):  
L.-M. Berger ◽  
M. Herrmann ◽  
M. Nebelung ◽  
S. Thiele ◽  
R.B. Heimann ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Thermal Spraying ◽  
Wear Test ◽  
Atmospheric Plasma ◽  
Powder Injection ◽  
Binder Phase ◽  
X Ray Diffraction ◽  
Abrasion Wear ◽  
Detonation Gun ◽  
First Time

Abstract Thermal spraying of silicon nitride has been considered impossible because the high temperatures of the spray processes lead to its decomposition and oxidation. To suppress the degradation oxide bonded silicon nitride spray powders (OBSN) have been developed. In this paper spray experiments with these powders by detonation gun spraying (DGS) and atmospheric plasma spraying (APS) with axial powder injection are described. All coatings were characterized using optical microscopy and X-ray diffraction. In addition, DGS coatings were also investigated using SEM, microhardness testing and a rubber wheel abrasion wear test. For the first time, relatively dense Si3N4-rich coatings with an oxide binder phase were produced. The abrasion wear resistance of some DGS coatings was found to be sufficiently high to envisage industrial application. Further progress is expected from optimized spray experiments with variations of spray powder composition and particle size.

Direct Moulding of Rubber Granules and Powders from Tyre Recycling

2013 ◽  
Vol 371 ◽  
pp. 315-319 ◽  
Author(s):  
Fabrizio Quadrini ◽  
Denise Bellisario ◽  
Loredana Santo ◽  
Ivica Hren
Keyword(s):  
Tensile Tests ◽  
Compression Moulding ◽  
Moulding Process ◽  
Particle Properties ◽  
Bound Rubber ◽  
Sample Density ◽  
Rubber Particles ◽  
Moulding Pressure ◽  
One Year ◽  
First Time

SMART project (Sustainable Moulding of Articles from Recycled Tyres) is a research project financed by the European Commission with the aim of developing a new moulding process of granules and powders from tyre recycling without any addition of virgin rubber or linking agent. The so called “direct moulding” is a compression moulding process which is directly applied to rubber particles from tyre grinding. After one year of activities, the new moulding process has been deeply investigated and some results are reported in the current work for the first time. Rubber granules and powders were produced by GumiImpex (partner of the European project) thanks to different technologies: particles from tyre grinding and buffings from tyre machining. Different size distributions of rubber particles and buffings were used to produce rubber sheets with the size of 200x200x5 mm3at the temperature of 160°C and the pressure of 3 MPa by using aluminium moulds. Tensile specimens were extracted from the sheets and tensile tests were performed and related to sample density and particle properties. Rubber densities over 1 g/cm3have been reached for all the samples with ultimate tensile strength and maximum elongation up to 1 MPa and 80%, respectively. These mechanical data are very promising in comparison with properties of polyurethane bound rubber composites. Increasing moulding pressure and temperature would lead to higher mechanical properties, if necessary.

scholarly journals Comparative Study with 89Y-foil and 89Y-pressed Targets for the Production of 89Zr †

2018 ◽  
Vol 8 (9) ◽  
pp. 1579 ◽  
Author(s):  
Aiman Alnahwi ◽  
Sébastien Tremblay ◽  
Brigitte Guérin
Keyword(s):  
Gamma Ray ◽  
Molar Activity ◽  
Icp Ms ◽  
Custom Made ◽  
The Us ◽  
General Limit ◽  
Foil Target ◽  
First Time ◽  
Metallic Impurities ◽  
Very High

Zirconium-89 (89Zr, t1/2 = 3.27 days) owns great potential in nuclear medicine, being extensively used in the labelling of antibodies and nanoparticules. 89Zr can be produced by cyclotron via an 89Y(p,n)89Zr reaction while using an 89Y-foil target. In this study, we investigated for the first time the use of 89Y-pressed target for the preparation of 89Zr-oxalate via a (p,n) reaction. We performed comparative studies with an 89Y-foil target mounted on custom-made target supports. A new automated cassette-based purification module was used to facilitate the purification and the fractionation of 89Zr-oxalate. The effective molar activity (EMA) was calculated for both approaches via titration with deferoxamine (DFO). The radionuclidic purity was determined by gamma-ray spectroscopy and the metal impurities were quantified by ICP-MS on the resulting 89Zr-oxalate solution. The cassette-based purification process leading to fractionation is simple, efficient, and provides very high EMA of 89Zr-oxalate. The total recovered activity was 81 ± 4% for both approaches. The highest EMA was found at 13.3 MeV and 25 μA for 0.25-mm thick 89Y-foil. Similar and optimal production yields were obtained at 15 MeV and 40 μA while using 0.50-mm thick 89Y-foil and pressed targets. Metallic impurities concentration was below the general limit of 10 ppm for heavy metals in the US and Ph.Eur for both 89Y-foil and pressed targets. Overall, these results show that the irradiation of 89Y-pressed targets is a very effective process, offering an alternative method for 89Zr production.

scholarly journals The Temperature Gradient-Forming Device, an Accessory Unit for Normal Light Microscopes To Study the Biology of Hyperthermophilic Microorganisms

2014 ◽  
Vol 80 (15) ◽  
pp. 4764-4770 ◽  
Author(s):  
Maximilian Mora ◽  
Annett Bellack ◽  
Matthias Ugele ◽  
Johann Hopf ◽  
Reinhard Wirth
Keyword(s):  
Temperature Gradient ◽  
Elevated Temperatures ◽  
Strictly Anaerobic ◽  
Heating Rates ◽  
Content Type ◽  
Custom Made ◽  
Temperature Ranges ◽  
Limited Degree ◽  
Normal Light ◽  
First Time

ABSTRACTTo date, the behavior of hyperthermophilic microorganisms in their biotope has been studied only to a limited degree; this is especially true for motility. One reason for this lack of knowledge is the requirement for high-temperature microscopy—combined, in most cases, with the need for observations under strictly anaerobic conditions—for such studies. We have developed a custom-made, low-budget device that, for the first time, allows analyses in temperature gradients up to 40°C over a distance of just 2 cm (a biotope-relevant distance) with heating rates up to ∼5°C/s. Our temperature gradient-forming device can convert any upright light microscope into one that works at temperatures as high as 110°C. Data obtained by use of this apparatus show how very well hyperthermophiles are adapted to their biotope: they can react within seconds to elevated temperatures by starting motility—even after 9 months of storage in the cold. Using the temperature gradient-forming device, we determined the temperature ranges for swimming, and the swimming speeds, of 15 selected species of the genusThermococcuswithin a few months, related these findings to the presence of cell surface appendages, and obtained the first evidence for thermotaxis inArchaea.

Investigation of Electrostatic Cantilever-Type Micromechanical Actuator

2006 ◽  
Vol 113 ◽  
pp. 179-184
Author(s):  
Rolanas Dauksevicius ◽  
Vytautas Ostaševičius ◽  
Sigitas Tamulevičius ◽  
Algimantas Bubulis ◽  
Rimvydas Gaidys
Keyword(s):  
Experimental Studies ◽  
Laser Doppler Vibrometer ◽  
Element Model ◽  
Nickel Surface ◽  
Switching Speed ◽  
Air Damping ◽  
University Of Technology ◽  
Cantilever Structure ◽  
First Time ◽  
Initial Results

Electrostatic microswitch and its fabrication technology have been developed for the first time in Lithuania, at Kaunas University of Technology (KTU). The microdevices were produced by using a nickel surface micromachining process. The microswitch consists of a cantilevered nickel structure suspended over the bottom electrodes. The width of the structure is 30 μm, thickness - 2 μm and length ranges from 67 to 150 μm. Implementation of microswitches as a substitute for the present solid-state switching devices poses many problems. In particular higher actuation voltages, lower switching speed and a reduced lifetime are considered to be among the most significant ones. With the aim of improving these parameters a finite element model is currently developed that takes into account not only microscale-specific electrostatic actuation and air damping effects but also includes the bouncing phenomena. Experimental studies of electrical and dynamic characteristics were also carried out with the purpose of model validation and correction. The paper presents initial results of theoretical modal and air damping analysis as well it shows the first attempts to measure vibration modes of the cantilever structure of the microswitch using Laser Doppler vibrometer.

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