An Empirical Study of Boss/Seat Materials and Geometries for Ultra Low-Leakage MEMS Micro-Valves

2005 ◽  
Author(s):  
Bernard A. Lynch ◽  
Brian G. Jamieson ◽  
Patrick A. Roman ◽  
Charles M. Zakrzwski
Keyword(s):  
Soft Materials ◽  
Knife Edge ◽  
Parylene C ◽  
Test Fixture ◽  
Low Leakage ◽  
Sealing Capacity ◽  
Ring Configuration ◽  
Sealing Pressure ◽  
Set Up

We report work on the testing and characterization of the sealing properties of various micro-valve seat/boss interfaces. Using a custom test set-up, we have measured helium leak rates for a variety of boss materials and seat geometries. The seat geometries are micro-machined in silicon, and an orifice is DRIE etched through the chip. The test fixture allows for leak-tight edge sealing of seat chips against a viton o-ring, independent of the force used to seal the boss against the seat. Bosses are sealed against the various seat chips with forces up to 400 mN by using a precision micrometer to deflect a small spring that is coupled to the boss chip. Soft metals, such as copper and gold, and polymers such as polydimethylsiloxane (PDMS) and parylene-c, coated on silicon boss chips have been tested on hard silicon seats. In all cases, leak rates were determined as a function of sealing pressure. Seat geometries include a concentric o-ring configuration, and a silicon knife-edge. Both seats have orifice diameters varying from 60 to 110 μm. Experimental results indicate that practical MEMS-scale forces (up to several hundred mN) are sufficient to cause deformation of the soft materials coating the bosses given the small loading area, which can improve sealing capacity but not repeatability. However, uneven loading of the boss prevented a tight seal across the entire seat, which is reflected in the leak rates detected. Soft boss-materials, like PDMS, however, have shown promising results for obtaining ultra-low leak rates. Leak rates as low as 1 × 10−4 atm·cc/sec were obtained on knife-edge seats with 110 μm diameter orifices.

Rapid, Refined, and Robust Method for Expression, Purification, and Characterization of Recombinant Human Amyloid-beta M1-42

2019 ◽  
Author(s):  
Priya Prakash ◽  
Travis Lantz ◽  
Krupal P. Jethava ◽  
Gaurav Chopra
Keyword(s):  
Amyloid Beta ◽  
Western Blots ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force ◽  
Set Up ◽  
Short Time

Amyloid plaques found in the brains of Alzheimer’s disease (AD) patients primarily consists of amyloid beta 1-42 (Ab42). Commercially, Ab42 is synthetized using peptide synthesizers. We describe a robust methodology for expression of recombinant human Ab(M1-42) in Rosetta(DE3)pLysS and BL21(DE3)pLysS competent E. coli with refined and rapid analytical purification techniques. The peptide is isolated and purified from the transformed cells using an optimized set-up for reverse-phase HPLC protocol, using commonly available C18 columns, yielding high amounts of peptide (~15-20 mg per 1 L culture) in a short time. The recombinant Ab(M1-42) forms characteristic aggregates similar to synthetic Ab42 aggregates as verified by western blots and atomic force microscopy to warrant future biological use. Our rapid, refined, and robust technique to purify human Ab(M1-42) can be used to synthesize chemical probes for several downstream in vitro and in vivo assays to facilitate AD research.

Isolation and characterization of oleochemical compounds from watermelon seed

2020 ◽  
Vol 10 (4) ◽  
pp. 79-82
Author(s):  
Madhubhushan M ◽  
Seshaiah S ◽  
Chandrudu J ◽  
Sagar R ◽  
Akila CR
Keyword(s):  
Cutting Tool ◽  
Citrullus Lanatus ◽  
Fatty Esters ◽  
Mineral Oils ◽  
Light Yellow ◽  
Isolation And Characterization ◽  
The Common ◽  
Set Up ◽  
Natural Gradation

The common watermelon item (Citrullus lanatus) seeds were gained from castoffs verdant nourishments for use by decorating, sun ventilation and pulverizing. Light yellow-toned oil was gotten by dissolvable withdrawal using oil atmosphere and the going with traits were gotten using oil ether: pH, refractive rundown, thickness, dissolvable miscibility, coagulating temperature, fire nature, express gravity, streak point and warmth of consuming. With a shallow level of unsaturation, stepped level of smoothness, and proximity of raised degree of the sensible proportion of free unsaturated fats. The low assessment of the solidifying temperature of the oil offered a hint that the oil can be managed in various areas paying little heed to the qualification in temperature. The following level of linoleic destructive of the oil offers a hint of natural gradation of solidarity. Fatty esters are increasing expanding significance as a biodegradable swap for mineral oils. In some request regions, for example, cutting tool oil, gearbox, pressure-driven oils, and greases for raw petroleum creation, the oleochemical items are set up. Nonetheless, certain particular wellsprings of fatty esters are hitherto to be abused for this comparative reason. This exploration subsequently tests into one of the less used wellsprings of fatty esters in watermelon. The oil from the kernels demonstrations a top-notch yield presents significant utilitarian gatherings for change and thus was utilized to set up an assortment of oleochemicals which demonstrated excellence materials in contrast with the routinely utilized oils feed frameworks for oleochemicals after portrayal. The photopolymers acquired indicated piercing vinyl protons for consistent polymerize.

Knife-edge test for characterization of subnanometer deformations in micro-optical surfaces

1999 ◽  
Author(s):  
Frederic Zamkotsian ◽  
Kjetil Dohlen ◽  
Patrick Lanzoni ◽  
Silvio P. Mazzanti ◽  
Marie-Laurence Michel ◽  
...  
Keyword(s):  
Knife Edge ◽  
Optical Surfaces

Materials and Physical Properties of Novel High-k and Medium-k Gate Dielectrics

2001 ◽  
Vol 670 ◽  
Author(s):  
Ran Liu ◽  
Stefan Zollner ◽  
Peter Fejes ◽  
Rich Gregory ◽  
Shifeng Lu ◽  
...  
Keyword(s):  
Thin Film ◽  
Transition Metal Oxides ◽  
Gate Dielectrics ◽  
Low Leakage ◽  
Low Leakage Current ◽  
High K ◽  
Compositional Properties ◽  
Sharp Interfaces ◽  
Selection Of

ABSTRACTRapid shrinking in device dimensions calls for replacement of SiO2 by new gate insulators in future generations of MOSFETs. Among many desirable properties, potential candidates must have a higher dielectric constant, low leakage current, and thermal stability against reaction or diffusion to ensure sharp interfaces with both the substrate Si and the gate metal (or poly-Si). Extensive characterization of such materials in thin-film form is crucial not only for selection of the alternative gate dielectrics and processes, but also for development of appropriate metrology of the high-k films on Si. This paper will report recent results on structural and compositional properties of thin film SrTiO3 and transition metal oxides (ZrO2and HfO2).

scholarly journals Experimental tests for characterization of GPR antenna patterns

1994 ◽  
Vol 37 (5 Sup.) ◽  
Author(s):  
E. Pettinelli ◽  
N. Pierdicca ◽  
S. Piro ◽  
L. Versino
Keyword(s):  
Radiation Pattern ◽  
National Research Council ◽  
Experimental Tests ◽  
Radar Signal ◽  
Antenna Radiation ◽  
Buried Structures ◽  
Antenna Radiation Pattern ◽  
The Difference ◽  
Set Up

Detection and location of buried structures using the electromagnetic impulsive methodologies (GPR) require the study of the spatial distribution of energy irradiated by an antenna into the ground and the mechanisms of wave propagation and scattering from relevant targets. Evaluation of the difference in wave field distribution in the ground with respect to free space can provide some useful indications on the propagation of the Geo-radar signal in the ground and the spatial resolution capability of the GPR method. For this reason, a research group, involving “La Sapienza” University, Rome and the National Research Council began, during 1992, to perform studies on antenna radiation pattern, the propagation and scattering phenomena of GPR. This paper presents the experimental set up and the obtained results on the antenna radiation pattern.

scholarly journals Visual Biochemistry: modular microfluidics enables kinetic insight from time-resolved cryo-EM

2020 ◽  
Author(s):  
Märt-Erik Mäeots ◽  
Byungjin Lee ◽  
Andrea Nans ◽  
Seung-Geun Jeong ◽  
Mohammad M. N. Esfahani ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Reaction Intermediates ◽  
Protein Distribution ◽  
Time Resolved ◽  
Biochemical Processes ◽  
Molecular Events ◽  
Biophysical Analysis ◽  
Common Strategy ◽  
Set Up

AbstractMechanistic understanding of biochemical reactions requires structural and kinetic characterization of the underlying chemical processes. However, no single experimental technique can provide this information in a broadly applicable manner and thus structural studies of static macromolecules are often complemented by biophysical analysis. Moreover, the common strategy of utilizing mutants or crosslinking probes to stabilize otherwise short-lived reaction intermediates is prone to trapping off-pathway artefacts and precludes determining the order of molecular events. To overcome these limitations and allow visualisation of biochemical processes at near-atomic spatial resolution and millisecond time scales, we developed a time-resolved sample preparation method for cryo-electron microscopy (trEM). We integrated a modular microfluidic device, featuring a 3D-mixing unit and a delay line of variable length, with a gas-assisted nozzle and motorised plunge-freeze set-up that enables automated, fast, and blot-free sample vitrification. This sample preparation not only preserves high-resolution structural detail but also substantially improves protein distribution across the vitreous ice. We validated the method by examining the formation of RecA filaments on single-stranded DNA. We could reliably visualise reaction intermediates of early filament growth across three orders of magnitude on sub-second timescales. Quantification of the trEM data allowed us to characterize the kinetics of RecA filament growth. The trEM method reported here is versatile, easy to reproduce and thus readily adaptable to a broad spectrum of fundamental questions in biology.

scholarly journals From ‘ontological metaphor’ to semiotic make-believe: giving shape and substance to fictive objects of conception with the ‘globe gesture’

Signo ◽  
2016 ◽  
Vol 41 (70) ◽  
pp. 29 ◽  
Author(s):  
Jean-Remi Lapaire
Keyword(s):  
Mental Representations ◽  
Controlled Environment ◽  
Cognitive Artifact ◽  
Emotional Appeal ◽  
Physical Presence ◽  
Sense Of Reality ◽  
Suspension Of Disbelief ◽  
Set Up ◽  
High Degree

Speakers are moving cognizers who engage in bodily acts of conceptualization. The “globe gesture” is among the most spectacular forms of “manual thinking” (Streeck 2009) used in formal talk. A characterization of the kinesic action typical of the “globe gesture” is first provided that shows how “the image of a bounded, supportable object” is created (McNeill 1992) and set up in gesture space. As conceptual objects are created and masses of semantic substance fashioned, visible shape is given to shapeless mental representations. A powerful semiotic trick is performed with a simple cognitive artifact. Interestingly, a willing suspension of disbelief is required of speakers and listeners who must temporarily give up their rational conceptions of visibility, materiality and palpability to watch the symbolic manipulation of invisible objects. The basic expressive properties of the “globe gesture” are next characterized: outlining and isolating objects of conception; neutralizing semantic specification; establishing a joint focus of attention and imagination; shaping, displaying and unifying content; creating a sense of reality and existence through physical presence. Iconic modifications of the standard metaphoric hand configuration, virtuosic elaborations and creative blends are finally examined before reporting the results of an experimental study of the globe gesture’s heuristic properties in a controlled environment. 14 students attending a multimodal “kineflective” seminar used the hand configuration to engage in “choreographic thinking” (Forsythe 2009) and develop a haptic understanding of derivation, nominalization, substantivation, conceptual reification. The globe gesture acted as a facilitator so long as a high degree of generality was maintained but was promptly discarded when words with a strong emotional appeal were introduced (e.g. sadness, madness). Emblems and iconic gestures were spontaneously performed instead.

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