Improving Photoresist Spray Coating on 3D Structures for Microfluidic Devices

2012 ◽  
Vol 1427 ◽  
Author(s):  
Shinya Kumagai ◽  
Naoya Fukuda ◽  
Hisayoshi Tajima ◽  
Minoru Sasaki

ABSTRACTSpray coating of a photoresist onto three-dimensional (3D) structure was investigated. To improve the uniformity of photoresist deposition onto the 3D structure, a shield plate with an aperture was used. The shield plate set over a sample permitted the resist deposition on the sample surface located in the aperture area while the plate blocked the deposition for the other area. The spray flow which is suitable for the resist deposition can be used effectively. Numerical analysis revealed that the vertical velocity component of gas flow was enhanced in the aperture area. In the experiments of the spray coating, the difference between the resist film thicknesses deposited on top and bottom trench surfaces was decreased. On the trench sidewall, resist bump formation, which was frequently observed in spray coating, was suppressed. The uniform resist deposition is necessary to realize 3D microdevices by lithography. In the microfluidic devices of dielectrophoresis, aside from the top and botttom trench surfaces, the trench sidewall can be used to fabricate device structures such as electrode for dielectrophoresis.

2016 ◽  
Vol 40 (2) ◽  
pp. 201-205 ◽  
Author(s):  
C. J. Daly ◽  
J. M. Bulloch ◽  
M. Ma ◽  
D. Aidulis

Sophisticated three-dimensional animation and video compositing software enables the creation of complex multimedia instructional movies. However, if the design of such presentations does not take account of cognitive load and multimedia theories, then their effectiveness as learning aids will be compromised. We investigated the use of animated images versus still images by creating two versions of a 4-min multimedia presentation on vascular neuroeffector transmission. One version comprised narration and animations, whereas the other animation comprised narration and still images. Fifty-four undergraduate students from level 3 pharmacology and physiology undergraduate degrees participated. Half of the students watched the full animation, and the other half watched the stills only. Students watched the presentation once and then answered a short essay question. Answers were coded and marked blind. The “animation” group scored 3.7 (SE: 0.4; out of 11), whereas the “stills” group scored 3.2 (SE: 0.5). The difference was not statistically significant. Further analysis of bonus marks, awarded for appropriate terminology use, detected a significant difference in one class (pharmacology) who scored 0.6 (SE: 0.2) versus 0.1 (SE: 0.1) for the animation versus stills group, respectively ( P = 0.04). However, when combined with the physiology group, the significance disappeared. Feedback from students was extremely positive and identified four main themes of interest. In conclusion, while increasing student satisfaction, we do not find strong evidence in favor of animated images over still images in this particular format. We also discuss the study design and offer suggestions for further investigations of this type.


Author(s):  
Chiara Melloni

Subordinate and synthetic represent well-attested modes of compounding across languages. Although the two classes exhibit some structural and interpretative analogies cross-linguistically, they denote distinct phenomena and entail different parameters of classification. Specifically, subordinate makes reference to the grammatical relation between the compound members, which hold a syntactic dependency (i.e., head-argument) relation; synthetic makes reference to the synthesis or concomitance of two processes (i.e., compounding and derivation). Therefore, while the former term implies the presence of a syntactic relation realized at the word level, the latter has strictly morphological implications and does not directly hinge on the nature of the relation between the compound members. Typical examples of subordinate compounds are [V+N]N formations like pickpocket, a class which is scarcely productive in English but largely attested in most Romance and many other languages (e.g., Italian lavapiatti ‘wash-dishes, dishwater’). Other instances of subordinate compounds are of the type [V+N]V, differing from the pickpocket type since the output is a verb, as in Chinese dài-găng ‘wait for-post, wait for a job’. The presence of a verb, however, is not compulsory since possible instances of subordinate compounds can be found among [N+N]N, [A+N]A, and [P+N]N/A compounds, among others: The consistent feature across subordinate compounds is the complementation relation holding between the constituents, whereby one of the two fills in an argumental slot of the other constituent. For instance, the N tetto ‘roof’ complements P in the Italian compound senza-tetto ‘without-roof, homeless person’, and the N stazione ‘station’ is the internal argument of the relational noun capo in capo-stazione ‘chief-station, station-master’. Synthetic compounds can envisage a subordination relation, as in truck driv-er/-ing, where truck is the internal argument of driver (or driving), so that they are often viewed as the prototypical subordinates. However, subordination does not feature in all synthetic compounds whose members can hold a modification/attribution relation, as in short-legged and three-dimensional: In these cases, the adjective (or numeral) is not an argument but a modifier of the other constituent. The hallmark of a synthetic compound is the presence of a derivational affix having scope over a compound/complex form, though being linearly attached and forming an established (or possible) word with one constituent only. This mismatch between semantics and formal structure has engendered a lively theoretical debate about the nature of these formations. Adopting a binary-branching analysis of morphological complexes, the debate has considered whether the correct analysis for synthetic compounds is the one shown in (1) or (2), which implies answering the question whether derivation applies before or after compounding. (1) a.[[truck] [driv-er]] b. [[short] [leg(g)-ed]] (2) a. [[[truck] [drive]] -er] b. [[[short] [leg(g)]]-ed] Interestingly, the structural and interpretative overlap between subordinate and synthetic compounds with a deverbal head is well represented across language groups: Synthetic compounds of the type in (1–2) are very productive in Germanic languages but virtually absent in Romance languages, where this gap is compensated for by the productive class of subordinate [V+N]N compounds, like Italian porta-lettere ‘carry-letters, mailman’, which are the interpretative analogous of Germanic synthetic formations. The difference between the two complexes lies in constituent order, V+N in Romance versus N+V in Germanic, and lack of an (overt) derivational affix in Romance languages.


1993 ◽  
Vol 122 (6) ◽  
pp. 1277-1283 ◽  
Author(s):  
VK Vinson ◽  
SJ Archer ◽  
EE Lattman ◽  
TD Pollard ◽  
DA Torchia

We have determined a medium resolution three-dimensional solution structure of Acanthamoeba profilin-I by multidimensional nuclear magnetic resonance spectroscopy. This 13-kD actin binding protein consists of a five stranded antiparallel beta sheet flanked by NH2- and COOH-terminal helices on one face and by a third helix and a two stranded beta sheet on the other face. Data from actin-profilin cross-linking experiments and the localization of conserved residues between profilins in different phyla indicate that actin binding occurs on the molecular face occupied by the terminal helices. The other face of the molecule contains the residues that differ between Acanthamoeba profilins-I and II and may be important in determining the difference in polyphosphoinositide binding between these isoforms. This suggests that lipids and actin bind to different faces of the molecule.


2019 ◽  
Vol 63 (1) ◽  
Author(s):  
Juan Carlos Martínez-Hernández ◽  
Iris N. Serratos ◽  
César Millán-Pacheco ◽  
Arturo Rojo-Domínguez ◽  
Jaqueline Padilla-Zúñiga

Human cathepsins K, L, and S, which are involved in the development of several serious diseases, are strongly inhibited by their related prosegments, to which they are covalently bound or simply forming complexes. In this work, three-dimensional structures of the three natural complexes of these enzymes with their related proregions were constructed, as well as six chimeric complexes of the same three prosegments with their non-cognate enzymes. We made a comparative study of the contacts in all nine structures throughout their active sites. The analysis was performed looking for a structural parameter that could agree with the values of the inhibition constants reported experimentally for each of the nine complexes. We found that this correlating parameter was the difference of the electrostatic energy (involving hydrogen bonds and ion pairs) at the binding interface of a 13-amino acid fragment of the prosegments. We used the results of this work, on the one hand, to identify the key residues involved in the electrostatic intermolecular recognition in each studied complex and, on the other, to explain some results achieved by different research groups on the inhibition of the same enzymes analyzed here. It was found that the natural cathepsin L complex showed a higher number of electrostatic interactions, some of them interconnected, when compared to the other two natural complexes. In addition, the chimeric contacts revealed binding sites that could be used to achieve a more potent inhibition of these cathepsins, avoiding cross-interactions.


2014 ◽  
Vol 1041 ◽  
pp. 31-34 ◽  
Author(s):  
Erik Šagát ◽  
Libor Matějka

This article discusses a numerical model to evaluate the influence of inlet/outlet insect grilles in naturally ventilated facades. Two models were created for this comparison. The difference between these models is in inlet and outlet openings. One model is fitted with insect grilles and the other one without insect grilles. Both models are three dimensional vertical ventilated cavity. Boundary conditions fit to summer season. In particular, the influence of insect grilles on airflow velocity and air temperature in the cavity are evaluated. The main goal of this work is to show the effect of openings size and geometry to functionality of natural ventilated constructions.


1961 ◽  
Vol 34 (3) ◽  
pp. 922-924
Author(s):  
L. I. Lyubchanskaya ◽  
A. S. Kuzminskiĭ

Abstract In sulfur vulcanizates the energy of the bond between the atoms of sulfur in the crosslinks may differ essentially from the energy of the bonds in the main chains of the polymer since, as is known, the thermal decomposition of the polysulfide bonds may be brought about at considerably lower temperatures than the decomposition of the main chains. It was found by one of the present authors2 that the thermal decomposition of the sulfur bonds brings about an inhibition of the oxidation which develops in the chains of the polymer. Consequently we must not regard the destruction of the chains and the decomposition of crosslinks as independent processes. Nevertheless the difference in the rates of destruction and decomposition is so great that these processes may be separated. There are in the literature different views as to which elements in the structure of the vulcanizates the processes of aging extend to. Tobolsky asserts that the chemical relaxation of stress is caused by oxidative destruction of the polymeric chain of the vulcanizate independently of its structure. On the other hand Watson and coworkers consider that the decomposition of the lattice of the vulcanizate is the result of scission of chemical crosslinks. In the present investigation it was established that, depending upon the composition of the vulcanizate and the conditions of the experiment, the process of aging may involve both the chains of polymer and the crosslinks, forming a three-dimensional lattice of the vulcanizates.


2010 ◽  
Vol 160 ◽  
pp. 75-82 ◽  
Author(s):  
Daniel Chateigner ◽  
B. Ouladdiaf ◽  
Francois Léon

We give the necessary formulas to extract pure magnetic diffraction signals from the difference spectra between two neutron texture measurements, one operated with a sample at zero-magnetic field, and the other under a magnetic field. This enables us to calculate the total-magnetic-scattering ODF, and the polarisation-magnetic-scattering ODF, of an iron sample. Using the developed approach it is shown that under some hypotheses one can describe the three dimensional orientation of the magnetic moments in the sample under a given magnetic field.


Author(s):  
A. K. Rai ◽  
P. P. Pronko

Several techniques have been reported in the past to prepare cross(x)-sectional TEM specimen. These methods are applicable when the sample surface is uniform. Examples of samples having uniform surfaces are ion implanted samples, thin films deposited on substrates and epilayers grown on substrates. Once device structures are fabricated on the surfaces of appropriate materials these surfaces will no longer remain uniform. For samples with uniform surfaces it does not matter which part of the surface region remains in the thin sections of the x-sectional TEM specimen since it is similar everywhere. However, in order to study a specific region of a device employing x-sectional TEM, one has to make sure that the desired region is thinned. In the present work a simple way to obtain thin sections of desired device region is described.


Author(s):  
Kenneth H. Downing

Three-dimensional structures of a number of samples have been determined by electron crystallography. The procedures used in this work include recording images of fairly large areas of a specimen at high tilt angles. There is then a large defocus ramp across the image, and parts of the image are far out of focus. In the regions where the defocus is large, the contrast transfer function (CTF) varies rapidly across the image, especially at high resolution. Not only is the CTF then difficult to determine with sufficient accuracy to correct properly, but the image contrast is reduced by envelope functions which tend toward a low value at high defocus.We have combined computer control of the electron microscope with spot-scan imaging in order to eliminate most of the defocus ramp and its effects in the images of tilted specimens. In recording the spot-scan image, the beam is scanned along rows that are parallel to the tilt axis, so that along each row of spots the focus is constant. Between scan rows, the objective lens current is changed to correct for the difference in specimen height from one scan to the next.


Author(s):  
J. Frank ◽  
B. F. McEwen ◽  
M. Radermacher ◽  
C. L. Rieder

The tomographic reconstruction from multiple projections of cellular components, within a thick section, offers a way of visualizing and quantifying their three-dimensional (3D) structure. However, asymmetric objects require as many views from the widest tilt range as possible; otherwise the reconstruction may be uninterpretable. Even if not for geometric obstructions, the increasing pathway of electrons, as the tilt angle is increased, poses the ultimate upper limitation to the projection range. With the maximum tilt angle being fixed, the only way to improve the faithfulness of the reconstruction is by changing the mode of the tilting from single-axis to conical; a point within the object projected with a tilt angle of 60° and a full 360° azimuthal range is then reconstructed as a slightly elliptic (axis ratio 1.2 : 1) sphere.


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