The microfluidic probe (MFP) is an open space microfluidic device that combines the concepts of hydrodynamic flow confinement (HFC) and scanning probes to overcome the closed channel restrictions of conventional microfluidic devices. In biology, this allows for analysis of mammalian cells, neurons and tissue samples that are otherwise difficult to culture in conventional microfluidic devices. In this paper, we demonstrate how 3-D printing can be used to expedite the design-test cycle of the MFP and hence democratize the concept. The 3D printing procedures were adapted in fabricating the MFPs that were used for all experiments. Characterization of MFP's flow profile footprints are performed by comparisons with numerically calculated profiles. Application of the MFP is then used to selectively label adherent cells cultured in a Petri dish, within their conventional culture environment. Results show that while the 3D printed probes contain some artifacts, they function just as well as MFPs microfabricated using conventional techniques. Overall, this fabrication demonstrates a rapid, easy, and affordable fabrication technique for the MFP.
In this study, we report the use of a high-throughput microfluidic spiral chip to screen out eggs from a mixed age nematode population, which can subsequently be cultured to a desired developmental stage. For the sorting of a mixture containing three different developmental stages, eggs, L1 and L4, we utilized a microfluidic spiral chip with trapezoidal channel to obtain sorting efficiency (SE) above 97% and sample purity (SP) above 80% for eggs at different flow rates up to 10 mL/min. The result demonstrated a cost effective, simple, and highly efficient method of synchronizing C. elegans at high throughput (~4,200 organisms/min at 6 mL/min), while eliminating challenges of clogging and non-reusability of membrane-based filtration. Due to its simplicity, our method can be easily adopted in the C. elegans research community.
Early diagnosis of the cardiac abnormalities during the pregnancy may reduce the risk of perinatal morbidity and mortality. Cardiotocography (CTG) is a means of recording the fetal heartbeat from the Doppler ultrasound (DUS) and the uterine contractions during the pregnancy and this method is commonly used to screen for fetal abnormalities. DUS, which is commonly used for monitoring the fetal heart rate, can also be used for identifying the event timings of fetal cardiac valve motions. In this study, a new technique called Swarm decomposition is proposed to analyze the fetal cardiac Doppler ultrasound signals for the fetal cardiac timing events estimation. Decomposing the fetal Doppler signal using the swarm intelligence achieved an excellent extraction of the fetal cardiac timing events in the most cases in early and late gestational ages of the pregnancy. Therefore, this technique would be useful for reliable screening of fetal wellbeing.
Liquefied gases are in common use for a variety of purposes, for example, liquid Propane serves as a domestic fuel, liquid Oxygen is carried in cylinders, and is provided to hospitals for patients suffering from breathing problems. In this study , simulation of air liquefaction process and its separation was done successfully using Advanced System for Process Engineering (ASPEN) Plus simulating tool in order to increase the quality of products and to decrease the operational cost simultaneously. The model under consideration was Linde single-column system. Also, the effect of variation of various process conditions on yield, purity of final product, and temperature were analyzed. Results obtained showed that by using Linde single column system, oxygen of almost 99% purity could be obtained. However, the purity of nitrogen obtained was only about 90%. As such, Linde single-column system can be used when oxygen is the desirable product. In the study, cost analysis of the processes was not considered. So, as a future recommendation, cost analysis can be done, leading to optimization of the entire process.
Pure cobalt ferrite and mixed cobalt nickel ferrites were prepared by sol-gel auto-combustion method. The structure was mainly investigated by X-Ray Diffraction. The catalytic activities of the prepared samples were investigated by studying the photo- and non-photocatalytic degradation of phenol using the High Performance Liquid Chromatography (HPLC).
Microalgae are generally mass produced in pure culture photobioreactors or in open ponds. While open ponds are generally cheaper to operate from a maintenance standpoint, an issue with them is that open systems allow for external microorganisms to interfere with the desired product yield. Understanding the effect of reactor conditions on co-culture setups of marine microalgae will allow for better design and operation to maximize product yield (in this case, single cell protein). The strains Nannochloropsis gaditana (CCAP649/5) and Tetraselmis chuii (UTEX LB232) are investigated in this study, first characterized separately and then co-cultured together.
Coupled with its superhydrophilicity, Titanium dioxide thin film owes its self-cleaning ability to organic pollutant degradation. Using commercially available titanium dioxide film by the Pilkington Glass, a model organic pollutant - 2-propanol - degradation was investigated under ultraviolet and solar simulated light irradiations. The photo-activities of both Pilkington ActivTM Clear (PAC) and Pilkington ActivTM Blue (PAB) under solar simulated light were comparable. However, irradiation under ultraviolet light enhanced 2-propanol photodegradation with PAC, whereas 2-propanol degradation was significantly reduced for PAB. Possible reasons for these variations were provided based on characterization results from Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Raman Spectroscopy and UV-Vis Spectroscopy. Variation of the degradation product concentration as monitored by Gas Chromatography (GC) is also used to explain the possible mechanism of 2-propanol degradation.
Chemical looping combustion (CLC) is a promising candidate for cost-effective CO2 capture and better power plant performance. The CLC process uses an oxygen carrier for the separation of oxygen from air. The oxygen is then used for fuel combustion. In this paper, the technical and economic performance of a power plant using CLC with two methods of waste heat utilization from the plant exhaust gas streams is studied. The plant studied is a natural gas-powered plant of 50MWth gross energy. The waste heat is utilized either a steam turbine or absorption chilling. The economic analysis shows a higher economic value of the waste utilization for cooling purpose compared to additional power generation. For the absorption chilling system, the cost of electricity (COE) is about 5.5 cents/kWh and has a payback period of about 6.4 years.
The thermal efficiency of open-tank volumetric solar receivers is limited by the excessive thermal losses consequent to high temperature operation. A transparent floating cover which limits the thermal losses by radiation and convection can be considered to substantially improve the thermal efficiency of the receiver. Herein, we describe the optical efficiency of a particular cover design. A ray-tracing tool is used on a solid model to determine the transmission though the elements of the cover. Optical efficiencies over 90% are reported.
Solar Rankine refrigeration systems can be driven using low-grade heat from solar thermal collectors. In this paper the development and validation of a thermodynamic model of a coupled organic Rankine cycle-vapor compression refrigeration system (ORC-VCR) is documented. Good agreement is obtained with previously published reference data. Parametric system performance analyses to key design and operating parameters are presented.
