Mixer For Use Research Articles

On the competition between mixing rate and uniformity in a coaxial hydrodynamic focusing mixer

Fast microfluidic mixers for use with line-of-sight integrating detection schemes pose unique challenges. Such detectors typically cannot discriminate signal from slow moving (e.g. near internal walls) and fast-moving portions of the fluid stream. This convolves reaction rate dynamics with fluid flow residence time dynamics. Further, the small cross sections of typical three-dimensional hydrodynamic focusing devices lead to lower detection signals. The current study focuses on achieving both small time scales of mixing and homogenous residence times. This is achieved by injecting sample through a center capillary and hydrodynamically focusing using a sheath flow within a tapered second capillary. The current design also features a third, larger coaxial capillary. The mixed stream flows into the large cross-section of this third capillary to decelerate and expand the stream by up to 14-fold to improve line-of-sight signal strength of reaction products. Hydrodynamic focusing, mixing, and expansion are studied using analytical and numerical models and also studied experimentally using a fluorescein-iodide quenching reaction. The experimentally validated models are used to explore trade-offs between mixing rate and uniformity. For the first time, this work presents detailed analysis of the Lagrangian time history of species transport during mixing inside coaxial capillaries to measure mixing nonuniformity. The mixing region enables order 100 μs mixing times and residence time widths of the same order (140 μs).

Implementation of LabVIEW as a Virtual Instrument in a Cost‐Effective Isolated Lung Setup

IntroductionIsolated lung experiments allow for ex vivo characterization of lung function and prove to be a valuable model for various fields such as cancer, lung transplantation, and ischemia/reperfusion injury. Unlike other models that require damaging the lung, the isolated lung allows for collection of physiological changes including airway pressure, pulmonary artery and vein pressure, airway flow, and, in our model, ventilated gas concentrations. We describe the use of LabVIEW combined with the free statistical software R for highly flexible, effective, and automated data collection in an isolated lung system.MethodsPressure transducers connected to bioamplifiers allow for collection of dynamic pulmonary artery and vein pressures, while airway pressure and flow are collected from the ventilator with the former used to visualize positive end expiratory pressure. Signals from these devices are connected to an analog‐digital converter from National InstrumentsTM that collects data into LabVIEW software, which is then automatically collected and displayed at 200Hz. Use of a roller pump with analog input/output allows for fully automated control of the perfusion speed. Output from a gas mixer for use in ventilated gas studies is collected and used to generate gas composition data. Additional experimental data that do not have signal output capability can be recorded manually in LabVIEW.ResultsLabVIEW is a reliable alternative to other commercially available data acquisition systems. The creation of a virtual instrument requires significant programming knowledge but allows for completely customizable data collection in a modular isolated lung system. Data become available in an Excel‐compatible file which can then be imported and analysed in R as another affordable alternative to commercial programs.ConclusionWe describe the design and implementation of a LabVIEW virtual instrument as an adjustable alternative to conventional data acquisition systems.Support or Funding InformationThis work was supported, in part, by institutional funds, NIH grant (5R01 HL123227), and a Merit Review Award (I01 BX003482) from the U.S. Department of Veterans Affairs Biomedical Laboratory R&D Service.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Optimisation of processing conditions and rheological properties using stephan mixer as conche in small‐scale chocolate processing

SummaryThis study investigated the suitability of Stephan mixer for use as conche during small‐scale chocolate production in an attempt to reduce cost and processing time. Molten chocolate was processed using the Stephan mixer under different temperature and time combinations and Buhler Elk'Olino conche (as reference), and the flow properties (Casson plastic viscosity, Casson yield stress and thixotropy) were studied using a shear‐rate‐controlled rheometer. Optimum settings of 65 °C for 10 min at 443 g dry conching followed by 50 °C for 15 min at 443 g wet conching in the Stephan mixer resulted in similar flow properties as the reference sample. Increasing the blade rotary speed for both dry and wet conching resulted in a decrease in flow properties. The Stephan mixer proved to be suitable for conching small‐scale (approximately 1 kg) chocolate productions and could be explored as a fast and cost‐effective method for small‐scale chocolate conching processes.

Transmission-Type Harmonic Mixers of MM-wave Range

A new kind of harmonic mixer for use in phase locking systems for MM-wave oscillators is presented. The mixer has compact design and combines directional coupler and conventional harmonic mixer in one element. Construction and features of the mixer are discussed. Experimentally measured main characteristics of the mixer are presented. Possibility of continuous frequency scan of phase locked MM-wave oscillator within a full waveguide band is demonstrated.

NbN Hot Electron Bolometer Mixers: Sensitivity, LO Power, Direct Detection and Stability

We demonstrate that the performance of NbN lattice cooled hot electron bolometer mixers depends strongly on the interface quality between the bolometer and the contact structure. Both the receiver noise temperature and the gain bandwidth can be improved by a factor of 2 by cleaning the interface and adding an additional superconducting interlayer to the contact pad. Using this we obtain a double sideband receiver noise temperature of 950 K at 2.5 THz and 4.3 K, using a 0.4/spl times/4 /spl mu/m HEB mixer with a spiral antenna. At the same bias point, we obtain an IF gain bandwidth of 6 GHz. To comply with current demands on THz mixers for use in space based receivers we reduce the device size to 0.15/spl times/1 /spl mu/m and use a twin slot antenna. We report measurements of the noise temperature, LO power requirement, stability and the direct detection effect, using a mixer with a 1.6 THz twin slot antenna and a 1.462 THz solid state LO source with calibrated output power.

Even harmonic double-balanced active mixer for use in direct conversion receivers

An active double-balanced even harmonic mixer implemented in a 0.35-/spl mu/m SiGe BiCMOS process is described. The effect of local oscillator wave shape and duty cycle on conversion gain are examined. Measured data for an even harmonic mixer is compared to a conventional Gilbert cell mixer and applications to the front-end of a direct conversion receiver are described.

Real time audio mixer

An audio mixer for use with audio input devices for buffering audio input signals in a dual buffering system where the dual buffering system includes a mass storage device and a dynamic storage device. The dual buffering system enables large quantities of audio data to be stored allowing audio effects and mixing capabilities including simulation of vinyl record scratching, inter alai. The audio mixer also automatically determine beats thus allowing beat skipping, automatic correction for audio input defects as well as synchronization of two or more audio inputs, inter alia.

Integrated-optical three-colour-mixing device

Using Rb↔K ion-exchanged channel waveguides and waveguide devices in KTP which combine a large wavelength range of singlemode operation in the visible region with the capability of both electro-optic modulation and guidance of high optical power, a three-colour mixer for use in a colour image generation system is demonstrated.

Self-pumping effects and radiation linewidth of Josephson flux-flow oscillators

Flux-flow oscillators (FFO's) are being developed for integration with a SIS mixer for use in submillimeter wave receivers. The present work contains a detailed experimental study of the dc, microwave, and noise properties of ${\mathrm{N}\mathrm{b}\ensuremath{-}\mathrm{A}\mathrm{l}\mathrm{O}}_{x}\ensuremath{-}\mathrm{Nb}$ FFO's. A model based on the Josephson self-pumping effect is proposed for an explanation of the experimental current-voltage characteristics. A reliable technique based on harmonic mixing is used to determine the spectral linewidth of the radiation emitted by the integrated FFO's up to 600 GHz. Comprehensive measurements of the dependence of the linewidth on the dynamic resistance and the applied magnetic field have been performed. In the resonant regime a linewidth as small as 200 kHz is obtained at 450 GHz. The experimental data are compared with recent theoretical predictions.

Liquid-liquid emulsification by static mixers for use in microencapsulation.

4e report a feasibility study on liquid-liquid emulsification by static mixers for use in microencapsulation. This study was concerned with developing a quantitative correlation between the size of the microspheres and process parameters. The process parameters considered included operational variables and physical properties associated with both the dispersion and dispersed phases. The effect of mixing element design on mixing efficiency and particle-size distribution was evaluated using three different static mixers. The performance of static mixers and conventional continuously stirred-tank reactors was assessed in several different aspects. Dimensional analysis was used to establish a correlation based on protein-free poly(lactic acid-co-glycolid acid) and poly(methyl methacrylate) microspheres in an oil-in-water emulsion using 1/4", 1/2" and 1" static mixers. This correlation accurately described the preparation of protein-loaded microspheres and provided large-scale microsphere production with a empirical basis.

All-Fiber Image-Rejection Receiver Front-End for Optical Communication Systems Using High-Birefringence and Polarizing Fibers

In this paper, we investigate in detail the conditions necessary for proper image-rejection operation and characterize the performance of a single detector, all-optical image-rejection mixer for use in heterodyne receivers. The principal component of the all-optical image-rejection receiver is a length of high-birefringence fiber. A polarizing fiber is also considered as an alternative to the high-birefringence fiber. The image-rejection performance is based on meeting certain required ideal conditions for polarization states of the desired and image channels. To study this, we examine, using the Stokes parameter approach, the evolution of certain figures of merit with distance in single-mode high-birefringence and polarizing fibers. Due to the nearness of the frequencies of the desired, image, and local oscillator (LO) signals, the mismatches from the ideal conditions are very small compared to the beat lengths. Therefore, there is negligible receiver error rate performance degradation. Our results indicate that this all-optical image-rejection receiver implementation is a robust device that is also highly insensitive to temperature variations.

Microstrip balanced diode mixers for X-band frequencies

A new balanced diode mixer for use in microstrip techniques is presented. Measurements show an LO to RF isolation of −25 dB, a noise figure and conversion loss of about 6dB over a frequency range of 7.5 to 12.5 GHz.

A low noise SIS receiver covering the frequency range 215?250 GHz

We have developed a heterodyne receiver incorporating an SIS mixer for use on a radiotelescope operating at 1.3 mm wavelength. The mixer has a minimum conversion loss of <2 dB and contributes less than 60 K to a total double side band receiver noise temperature of about 80 K at 220 GHz and 230 GHz. To our knowledge this represents the lowest receiver noise ever reported in this frequency range.

Selecting Mixers for Treatment Operations

Mixers for use in water and waste treatment come in many sizes and various designs, although their basic operating principles are the same. The final choice will depend on the demands of the particular application, but the size or type selected should be capable of modification to meet future contingencies.

Spectral analysis of a phase locked laser at 891 GHz, an application of Josephson junctions in the far infrared

We have used a Josephson junction to investigate the spectral purity of an HCN laser which is used in an infrared frequency synthesis chain. To obtain a narrower linewidth from the laser it has been phase locked to a multiplied microwave reference chain. A calculated value for this linewidth was based upon the measured noise spectrum of the microwave source and a theory due to Middleton. One can take advantage of the unique properties ofthe Josephson junction as a frequency multiplier and mixer for use in measuring this linewidth. The Josephson junction is driven by an X-band signal which is derived from a specially designed cavity stabilized klystron system of high spectral purity. The 92nd harmonic of the X-band signal is generated in the Josephson junction. In addition, the Josephson junction acts as a mixer of the harmonic signals and the 891 GHz output of the HCN laser. The 92nd harmonic beat signal is taken from the Josephson junction, amplified, and sent to a spectrum analyzer for frequency domain analysis. Details of the experiment, results, and relation to predicted linewidths are presented.

A 20-GHz Integrated Balanced Mixer

An integrated balanced mixer for use in the receiver for the quasi-millimeter-wave digital radio transmission system is described. The following aspects of the mixer realization are discussed. 1) The characteristics of gallium arsenide Schottky barrier diodes and three types of diode mount construction are described. The least observed dc incremental conversion loss was about 4 dB in the range of 18-23 GHz. 2) The fabrication of waveguide to microstrip transition, using a ridged waveguide transducer, is described. A transition loss of less than 0.38 dB was obtained in the range of 18-21.75 GHz. 3) The microstrip circuit elements, such as the 3-dB directional coupler and the low-pass filter, are described. The minimum isolation and coupling values of the coupler were about 16 dB and 3-4 dB, respectively. 4) The effect of the undesirable electromagnetic mode propagation on the integrated mixer operations is discussed. 5) The performance of the integrated balanced mixer is presented. This mixer, operated at a signal frequency of 20 /spl plus mn/0.5 GHz and at a local oscillator frequency of 18.3 GHz, showed a single side-band noise figure of 4.8-5.8 dB. 6) The reliability of the mixer is also evaluated with high reliability under vibration and shock testing being exhibited.

A mechanical mixer for use in the preparation of reversed-phase chromatographic packing.

A mechanical mixer for use in the preparation of reversed-phase chromatographic packing.