Analytical and bioanalytical chemistry, 2015 Nov., v. 407, no. 29, p. 8735-8743.
chemical analysis, equipment design, mass spectrometry, and equipment performance
A fast and straightforward method to prototype microfluidic chip systems for dead-volume-free hyphenation to electrospray-ionisation mass spectrometry is presented. The developed approach based on liquid-phase lithography provides an inexpensive and reliable access to microfluidic chips for MS coupling which can be manufactured in any laboratory with low technical demands. The rapid prototyping approach enables the seamless integration of capillaries serving as electrospray emitters with negligible dead volume. The high versatility of the presented prototyping method and the applicability of a variety of chip-based devices in different fields of lab-on-a-chip technology are established for analytical separations by means of chip-electrochromatography–MS and for continuous-flow synthesis using microreactor technology with MS detection.
The temperature dependence of surface tension and density for Fe–Cr–Mo (AISI 4142), Fe–Cr–Ni (AISI 304), and Fe–Cr–Mn–Ni TRIP/TWIP high-manganese (16 wt% Cr, 7 wt% Mn, and 3–9 wt% Ni) liquid alloys are investigated using the conventional maximum bubble pressure (MBP) and sessile drop (SD) methods. In addition, the surface tension of liquid steel is measured using the oscillating droplet method on electromagnetically levitated (EML) liquid droplets at the German Aerospace Centre (DLR, Cologne). The data of thermophysical properties for Fe–Cr–Mn–Ni is of major importance for modeling of infiltration and gas atomization processes in the prototyping of a “TRIP-Matrix-Composite.” The surface tension of TRIP/TWIP steel increased with an increase in temperature in MBP as well as in SD measurement. The manganese evaporation with the conventional measurement methods is not significantly high within the experiments (∆Mₙ < 0.5 %). The temperature coefficient of surface tension (dσ/dT) is positive for liquid steel samples, which can be explained by the concentration of surface active elements. A slight influence of nickel on the surface tension of Fe–Cr–Mn–Ni steel was experimentally observed where σ is decreased with increasing nickel content. EML measurement of high-manganese steel, however, is limited to the undercooling state of the liquid steel. The manganese evaporation strongly increased in excess of the liquidus temperature in levitation measurements and a mass loss of droplet of 5 % was observed.
Includes references Microchannel devices were constructed from low-temperature co-fired ceramic (LTCC) materials with screen-printed gold (SPG) electrodes in three dimensions—on all four walls—for self-contained enzyme-linked immunosorbant assays with electrochemical detection. The microchannel confines the solution to a small volume, allowing concentration of electroactive enzymatically generated product and nearby electrodes provide high-speed and high-sensitivity detection: it also facilitates future integration with microfluidics. LTCC materials allow easy construction of three-dimensional structures compared with more traditional materials such as glass and polymer materials. Parallel processing of LTCC layers is more amenable to mass production and fast prototyping, compared with sequential processing for integrating multiple features into a single device. LTCC and SPG have not been reported previously as the basis for microchannel immunoassays, nor with integrated, individually addressable electrodes in three dimensions. A demonstration assay for mouse IgG at 5.0 ng/mL (3.3 × 10⁻¹¹ M) with electrochemical detection was achieved within a 1.8 cm long × 290 μm high × 130 μm wide microchannel (approximately 680 nL). Two of four SPG electrodes span the top and bottom walls and serve as the auxiliary electrode and the assay site, respectively. The other two (0.7 cm long × 97 μm wide) are centered lengthwise on the sidewalls of the channel. One serves as the working and the other as the pseudoreference electrode. The immunoassay components were immobilized at the bottom SPG region. Enzymatically generated p-aminophenol was detected at the internal working electrode within 15 s of introducing the enzyme substrate p-aminophenyl phosphate. A series of buffer rinses avoided nonspecific adsorption and false-positive signals. [graphic removed]
Includes references A new design of a miniaturized, atmospheric-pressure, low-power (e.g., battery-operated), self-igniting, planar-geometry microplasma device (MPD) for use with liquid microsamples is described. The inexpensive MPD was a hybrid, three-substrate quartz-plastic-plastic structure and it was formed on chips with area the size of a small postage stamp. The substrates were chosen for rapid prototyping and for speedy device-geometry testing and evaluation. The ~700-μm (diameter) and 7-mm (long) He-H₂ (3% H₂) microplasma was formed by applying high-voltage ac between two needle electrodes. Operating conditions were found to be critical in sustaining stable microplasma on plastic substrates. Spectral interference from the electrode materials was not observed. A small-size, electrothermal vaporization system was used for introduction of microliter volumes of liquids into the MPD. The microplasma was operated from an inexpensive power supply. And, operation from a 14.4-V battery has been demonstrated. Microplasma background emission in the spectral range between 200 and 850 nm obtained using a portable, fiber-optic spectrometer is reported. Analyte emission from microliter volumes of dilute single-element standard solutions of Cd, Cu, K, Li, Mg, Mn, Na, Pb, and Zn is documented. Element-dependent precision was between 10-25% (the average was 15%) and detection limits ranged between 1.5 and 350 ng. The system was used for the determination of Na in diluted bottled-water samples.
International journal of parallel programming, 2009 Feb., v. 37, no. 1, p. 37-57.
Includes references The object-oriented scripting language Ruby is admired by many programmers for being easy to write in, and for its flexible, dynamic nature. In the last few years, the Ruby on Rails web application framework, popular for its productivity benefits, has brought about a renewed attention to Ruby for enterprise use. As the focus of Ruby has broadened from small tools and scripts, to large applications, the demands on Ruby's distributed object environment have also increased, as has the need for information about its usage, performance and examples of common practices. dRuby and Rinda were developed by the author as the distributed object environment and shared tuplespace implementation for the Ruby language, and are included as part of Ruby's standard library. dRuby extends method calls across the network while retaining the benefits of Ruby. Rinda builds on dRuby to bring the functionality of Linda, the glue language for distributed co-ordination systems, to Ruby. This article discusses the design policy and implementation points of these two systems, and demonstrates their simplicity with sample code and examples of their usage in actual applications. In addition to dRuby and Rinda's appropriateness for prototyping distributed systems, this article will also demonstrate that dRuby and Rinda are building a reputation for being suitable infrastructure components for real-world applications.
Bjornson, Robert D., Carriero, Nicholas J., Schultz, Martin H., Shields, Patrick M., and Weston, Stephen B.
International journal of parallel programming, 2009 Feb., v. 37, no. 1, p. 106-125.
Includes references As languages and systems for rapid prototyping and application development have grown in popularity and the problems that they are being used to solve have grown in size, so has the need for enhancing them with a coordination facility to support distributed and parallel computations and the creation of application ensembles. We describe NetWorkSpace, a coordination facility based on the fundamental concept of a variable/value binding. NetWorkSpace is implemented as an open source server with clients available for a variety of environments. We present an overview of its design, implementation, performance and usage case studies.
Kechagias, John, Iakovakis, Vassilis, Katsanos, Manolis, and Maropoulos, Stergios
Journal of materials science, 2008 Apr., v. 43, no. 8, p. 2522-2535.
models, electrodes, and manufacturing
Electrical discharge machining (EDM) is a non-conventional process for the manufacture of complex or hard material parts that are difficult to machine by conventional machining processes. During EDM, the electrode shape is mirrored in the workpiece. As a result, problems are transferred on the electrode manufacturing process. Rapid tooling (RT) is a new technology which uses rapid prototyping (RP) models to reduce the time and cost of tool manufacture. The various methods of manufacturing RT electrodes, with respect to different materials and the incorporated supplementary processes, are classified in the present work. Recent international research work on RT electrodes is reviewed and the results on the performance of RT electrodes are tabulated.
KUNIK, D., LUDUEÑA, S.J., COSTANTINO, S., and MARTÍNEZ, O.E.
Journal of microscopy, 2008 Mar., v. 229, no. 3, p. 540-544.
two-photon absorption, nanolithography, and Lithography
Includes references Improving the excitation conditions in two-photon fluorescent lithography reduces the size of the fabricated structures to nanometre scales. We demonstrate that a precise control of the illumination profile and the scanning speed of the laser beam is enough to decrease the photo-polymerization volume of resins by orders of magnitude. This work also shows experimental evidence of surface effects that yield a different polymerization intensity threshold compared with bulk. Such phenomenon enables to perform a non-linear optical nanolithography in a simple way, allowing fast-prototyping procedures. We present a detailed study of the polymer growth process using fluorescence and atomic force microscopy.
Fernando, Chrisantha, Von Kiedrowski, Günter, and Szathmáry, Eörs
Journal of molecular evolution, 2007 May, v. 64, no. 5, p. 572-585.
Temperature cycling, Self-replication, Minimal ribozyme, Tidal cycling, Nonenzymatic template replication, Origin of life, and nucleic acids
Includes references The origin of nucleic acid template replication is a major unsolved problem in science. A novel stochastic model of nucleic acid chemistry was developed to allow rapid prototyping of chemical experiments designed to discover sufficient conditions for template replication. Experiments using the model brought to attention a robust property of nucleic acid template populations, the tendency for elongation to outcompete replication. Externally imposed denaturation-renaturation cycles did not reverse this tendency. For example, it has been proposed that fast tidal cycling could establish a TCR (tidal chain reaction) analogous to a PCR (polymerase chain reaction) acting on nucleic acid polymers, allowing their self-replication. However, elongating side-reactions that would have been prevented by the polymerase in the PCR still occurred in the simulation of the TCR. The same finding was found with temperature and monomer cycles. We propose that if cycling reactors are to allow template replication, oligonucleotide phenotypes that are capable of favorably altering the flux ratio between replication and elongation, for example, by facilitating sequence-specific cleavage within templates, are necessary; accordingly the minimal replicase ribozyme may have possessed restriction functionality.
Analytical and bioanalytical chemistry, 2006 Aug., v. 385, no. 8, p. 1351-1361.
μTAS, Microfluidics, Laser, Micromachining, Bio-MEMS, and polymers
Includes references This paper reviews applications of laser-based techniques to the fabrication of microfluidic devices for biochips and addresses some of the challenges associated with the manufacture of these devices. Special emphasis is placed on the use of lasers for the rapid prototyping and production of biochips in particular for applications in which silicon is not the preferred material base. Part I of this review addresses applications and devices using UV lasers for laser ablation and surface treatment of microchannels, in particular in polymers.
Journal of materials science, 2006 Jan., v. 41, no. 1, p. 177-198.
manufacturing, sensors (equipment), composite materials, and ceramics
The last two decades have witnessed the proliferation piezoelectric composite transducers for an array of sensor and actuator applications. In this article, a concise summary of the major methods used in composite making, with special emphasis on Solid Freeform Fabrication (SFF), is provided. Fused Deposition of Ceramics (FDC) and Sanders Prototyping (SP) are two SFF techniques that have been utilized to make a variety of novel piezocomposites with connectivity patterns including (1-3), (3-2), (3-1), (2-2) and (3-3). The FDC technique has also been used to prototype a number of actuators such as tube arrays, spiral, oval, telescoping, and monomorph multi-material bending actuators. It has been demonstrated that SFF technology is a viable option for fabricating piezocomposite sensors and actuators with intricate geometry, unorthodox internal architecture, and complex symmetry. The salient aspects of processing of such composite sensors and actuators are summarized, and structure-processing-property relations are elaborated on.