Sorting Performances Research Articles

High-Density Microporous Drainage-Integrating Sheath Flow Generator for Streamlining Microfluidic Cell Sorting Systems.

Tremendous efforts have been made to develop practical and efficient microfluidic cell and particle sorting systems; however, there are technological limitations in terms of system complexity and low operability. Here, we propose a sheath flow generator that can dramatically simplify operational procedures and enhance the usability of microfluidic cell sorters. The device utilizes an embedded polydimethylsiloxane (PDMS) sponge with interconnected micropores, which is in direct contact with microchannels and seamlessly integrated into the microfluidic platform. The high-density micropores on the sponge surface facilitated fluid drainage, and the drained fluid was used as the sheath flow for downstream cell sorting processes. To fabricate the integrated device, a new process for sponge-embedded substrates was developed through the accumulation, incorporation, and dissolution of PMMA microparticles as sacrificial porogens. The effects of the microchannel geometry and flow velocity on the sheath flow generation were investigated. Furthermore, an asymmetric lattice-shaped microchannel network for cell/particle sorting was connected to the sheath flow generator in series, and the sorting performances of model particles, blood cells, and spiked tumor cells were investigated. The sheath flow generation technique developed in this study is expected to streamline conventional microfluidic cell-sorting systems as it dramatically improves versatility and operability.

On-chip sorting of orbital angular momentum beams using Bloch surface wave structures

Owing to their unique optical properties and new degrees of freedom, orbital angular momentum (OAM) beams have been applied in various fields. Detection of the topological charges (TCs) of OAM beams is the key step for their applications. However, on-chip sorting of OAM beams with large TCs still remains a challenge. In this paper, Bloch surface wave (BSW) structures with five semi-ring shaped nanoslits are modeled. A spatial separation of 135 nm on the chip is obtained between two neighboring OAM states. OAM beams with TCs up to 35 can be successfully sorted by the BSW structures, which is much larger than that using metallic structures (only seven). BSW structures exhibit better OAM sorting performances than metallic structures. We systematically show how the lower attenuation of BSW structures leads to far superior separation ability compared to surface plasmons propagating on metallic structures. In addition, sorting of two OAM beams with different TCs simultaneously can be achieved in this way. Our results reveal that BSW structures should be an excellent solution for OAM sorting with large TCs, which is beneficial for applications in integrated on-chip devices and optical communications.

Simulating Bulk Ore Sorting Performance of a Panel Cave Mine: A Comparison between Two Approaches

Conceptual bulk ore sorting studies are essential for determining a potential improvement in mine economics before undertaking on-site sensor trials. Two approaches, block modelling and drill core compositing, are applied to simulate the bulk ore sorting performance of mining operations. While one employs the grade data of a block model, the other approach utilizes composited drill core grades. This study aimed at comparing these two approaches by estimating in-situ grade heterogeneities and simulating the bulk ore sorting performances of the currently active caves of the Cadia East panel cave mine. The results show that block modelling tends to smooth the grade variability that initially exists in the drill core grade data. Particularly in the portions of the deposit where drilling is sparse or widely spaced compared to the selected block size, block modelling leads to lower grade heterogeneity and bulk ore sorting performance estimates. However, when the drill hole data is nonrepresentative of the area of interest, block modelling can predict more realistic bulk ore sorting performances compared to drill core grades. The assessments performed with the blocks and drill core composites of various sizes showed that grade heterogeneity was adversely affected by an increased sorting scale due to averaged metal grades.

Continuous Particle Separation Driven by 3D Ag-PDMS Electrodes with Dielectric Electrophoretic Force Coupled with Inertia Force.

Cell separation has become @important in biological and medical applications. Dielectrophoresis (DEP) is widely used due to the advantages it offers, such as the lack of a requirement for biological markers and the fact that it involves no damage to cells or particles. This study aimed to report a novel approach combining 3D sidewall electrodes and contraction/expansion (CEA) structures to separate three kinds of particles with different sizes or dielectric properties continuously. The separation was achieved through the interaction between electrophoretic forces and inertia forces. The CEA channel was capable of sorting particles with different sizes due to inertial forces, and also enhanced the nonuniformity of the electric field. The 3D electrodes generated a non-uniform electric field at the same height as the channels, which increased the action range of the DEP force. Finite element simulations using the commercial software, COMSOL Multiphysics 5.4, were performed to determine the flow field distributions, electric field distributions, and particle trajectories. The separation experiments were assessed by separating 4 µm polystyrene (PS) particles from 20 µm PS particles at different flow rates by experiencing positive and negative DEP. Subsequently, the sorting performances of the 4 µm PS particles, 20 µm PS particles, and 4 µm silica particles with different solution conductivities were observed. Both the numerical simulations and the practical particle separation displayed high separating efficiency (separation of 4 µm PS particles, 94.2%; separation of 20 µm PS particles, 92.1%; separation of 4 µm Silica particles, 95.3%). The proposed approach is expected to open a new approach to cell sorting and separating.

Simultaneous variable selection for the classification of near infrared spectra

This paper addresses the problem of wood wastes recycling automation. We propose variable selection methods based on near infrared spectroscopic data to select a set of wavebands that captures the main spectral peaks of wood materials to improve the sorting performances. The spectra are first jointly modeled as linear combinations of explanatory variables drawn from a collection of Gaussian-shaped functions. The aim is to select a common subset of wavebands shared by several spectra. The variable selection is then formulated as an unconstrained simultaneous sparse approximation problem in which the coefficients related to different spectra are encouraged to be piecewise constant, i.e. the coefficients associated to successive spectra should have comparable magnitudes. We also investigate the case where the coefficients are constrained to be nonnegative. These problems are solved using the fast iterative shrinkage-thresholding algorithm. The proposed approaches are illustrated on a dataset of 290 spectra of wood wastes; each spectrum is composed of 1647 wavelengths. We show that the selected variables lead to better classification performances as compared to standard approaches.

Expansion of arbitrary stimulus classes and function-transfer measured by sorting performances.

Sorting (SRT) and matching-to-sample (MTS) tests have measured the formation of arbitrary stimulus classes. This experiment used SRT and MTS tests to document the expansion of class size. Thirty-two participants learned 12 conditional discriminations with a linear series training structure (A➔B➔C➔D➔E). SRT tests documented the formation of 5-member classes by 17 of the participants. Thereafter, 6-member class expansion was implemented by FC training. Nine of these 17 participants showed class expansion when tracked with a sequence of an SRT, MTS, and a final SRT test, and the other 8 showed expansion when tracked with a sequence of MTS and SRT tests. Thus, SRT tests documented class expansion, and the sequence of tests did not influence class expansion. The 15 participants who did not form the 5-member classes learned the baselines for new 3-member classes (A➔B➔C) and formed them as documented by an SRT test. Then, 4-member class expansion was implemented by FB training. Expansion was assessed using the above-mentioned testing sequences. All 15 showed class expansion with 100% correspondence between the SRT and MTS performances. Sorting documented the expansion of arbitrary stimulus classes, while the MTS tests showed that the stimuli also functioned as members of equivalence classes.

Mode sorting performance for optical beams carrying orbital angular momentum suffering lateral displacement and angular deflection

Beams carrying orbital angular momentum (OAM) is expected to be a new degree of multiplexing to increase transmission capacity in the optical communication. Mode sorting methods have been reported so far as efficient ways to demultiplex such OAM multiplexed lightwaves. Since the OAM transmission is mainly through free-space, the transmitting OAM lightwave may suffer lateral displacement and angular deflection on the receiver plane. In this paper, we numerically investigate the tolerance to lateral displacement and angular deflection on the mode sorting performances for beams carrying OAM. Comparing the performance in terms of crosstalk in between high resolution and ordinary resolution mode sorting methods reveals that the high resolution one shows a slight lower crosstalk while almost the same tolerance as the ordinary resolution one.

Performance evaluation of optical sorting in mineral processing – A case study with quartz, magnesite, hematite, lignite, copper and gold ores

Optical sorting is increasingly playing an important role in mineral processing. Therefore, a better understanding of this method is required concerning general properties and mineral sorting applications. To date, optical sorting has been widely studied in terms of industrial applications and performance evaluation particularly in mineral processing. Nevertheless, process optimization requires better understanding of qualitative and quantitative figures based on real life sorting applications.In this study, the relationship between feed rate and separation efficiency of a gravity type and visible light responsive sensor mounted optical sorter (VIS sorter) was investigated. In addition to the feed rate, the effect of particle size on separation performance was also discussed. Laboratory studies included a selection of material, sample preparation, and optical sorting tests with magnesite, quartz, lignite, hematite, copper and gold ore samples. Experimental studies performed with different size fractions at varying feed rates were followed by evaluation of results with ROC (receiver operating characteristics) graphs. Recovery, grade, and capacity indicators are important to define the efficiency of the optical sorting. Alternatively, ROCs highlight missing particles and false alarm rates, which are used to characterize set points and detectability of the equipment/operation. In the tests performed with quartz and magnesite samples, % weights of valuable (white) and non–valuable (colored) particles in products were directly used to express the performance of optical sorting with ROC. Additionally, % Fe content, % dry ash content, % copper recovery and % gold recovery figures were used to define the ROC parameters for hematite, lignite, copper and gold ore samples.Results showed that the performance of the VIS type optical sorter mainly depends on correctly sorted amounts of valuable and non–valuable particles. Alongside with the evaluation of change in sorting performances in accordance with feed rate, ore type, and particle size; pre-concentration of copper and gold ores, concentration of hematite from alkaline waste, dry cleaning of lignite and market quality magnesite and quartz sorting applications with VIS type optical sorter were also discussed.

Magnetic Focusing and Hydrodynamic Deflection of Micro-Particles in A Microdevice

Cell and particle sorting is indispensable to drive medical diagnosis and immunomagnetic separation for applications in health and water monitoring. Microfluidic sorting methods offer cost-effective solutions to handling particles against conventional methods such as filtration and chromatography. But their sorting performances suffer from issues such as requirement of adulterating sheath flow in Pinched Flow Fractionation (PFF) [1]; low throughput in hydrodynamic filtration [2] and deterministic lateral displacement [3]; complex fabrication in magnetophoresis [4] and external energy consumption in dielectrophoresis [5] and acoustic separation [6]. We report a two-stage sorting microdevice capable of magnetophoretic focusing of 5µm and 11µm superparamagnetic particles and their hydrodynamic sorting at high throughput with no sheath flow. The device deploys magnetophoresis to align the randomly distributed superparamagnetic particles along the wall of a 40µm-wide microchannel using a permanent magnet. Center of particles follow distinct streamlines lying at a distance equal to their respective radii from the wall. The aligned particles then enter into an 8mm-wide expansion region hence getting separated from each other due to the increase in intra-distance between their respective laminar streamlines. We have achieved a throughput of 6ml/h, separation purity of 90%, and particles processing capacity of 10E6 per hour which is comparable or better than the above-mentioned methods with yet the advantage of sheath-flow less sorting of particles. These research findings shall be applied to innovate a microchip for separation of microorganism from water samples for its quality monitoring.[1] Yamada, M., Anal. Chem. 76, 5465 (2004).[2] Yamada, M. Lab Chip 5, 1233 (2005).[3] Huang, L. R., Science 304, 987 (2004).[4] Adams, J. D., PNAS 105, 18165 (2008).[5] Wang, X. Cell Separation by Dielectrophoretic. 72, 832 (2000).[6] Petersson, F. Lab Chip 5, 20 (2005).

An efficient and fast analytical procedure for the bromine determination in waste electrical and electronic equipment plastics

In this study, X-ray fluorescence (XRF) spectroscopy was used, in combination with micro-Raman spectroscopy, for a fast determination of bromine concentration and then of brominated flame retardants (BFRs) compounds in waste electrical and electronic equipments. Different samples from different recycling industries were characterized to evaluate the sorting performances of treatment companies. This investigation must be considered of prime research interest since the impact of BFRs on the environment and their potential risk on human health is an actual concern. Indeed, the new European Restriction of Hazardous Substances Directive (RoHS 2011/65/EU) demands that plastics with BFRs concentration above 0.1%, being potential health hazards, are identified and eliminated from the recycling process. Our results show the capability and the potential of Raman spectroscopy, together with XRF analysis, as effective tools for the rapid detection of BFRs in plastic materials. In particular, the use of these two techniques in combination can be considered as a promising method suitable for quality control applications in the recycling industry.

Study of the physico-chemical properties of recycled polymers from waste electrical and electronic equipment (WEEE) sorted by high resolution near infrared devices

Recycling of plastics from waste electrical and electronic equipment (WEEE) requires large scale high-performance sorting and identification technologies. The aim of this project is to evaluate the sorting performances of near infrared (NIR) devices, developed by the company PELLENC ST, for three styrenic polymers from WEEE: acrylonitrile-butadiene-styrene (ABS), high-impact polystyrene (HIPS) and ABS/polycarbonate blend (ABS/PC) and to study the physico-chemical properties of recycled materials. The use of an improved near infrared technique allows high levels of efficiency and performance to be achieved. This study can be used to evaluate the substitution ratio of virgin styrenic polymers by recycled ones for life cycle assessments (LCA) of reclaimed materials. Mechanical properties and fire properties of the sorted polymers were investigated. Mechanical properties of the polymers, particularly these of HIPS, were slightly modified after sorting. However, a degradation of the polybutadiene phase was observed. Fire tests revealed the presence of flame retardants in ABS and HIPS. Hence, NIR process could be used after a first sorting of brominated plastic wastes, in order to respect the RoHS directive. This project offers industrially viable alternatives for the recovery of plastics waste and the use of secondary raw materials.

Social inequality of reading literacy: A longitudinal analysis with cross-sectional data of PIRLS 2001 and PISA 2000 utilizing the pair wise matching procedure

In accordance to Boudon's structural-individualistic action model, it is the aim of this paper to investigate the casual effects of individual abilities, resources of the parental home, socially selective educational transitions as well as teaching and learning conditions in schools on the development of reading literacy and its dispersion in respect of social origin. It is assumed that the socially selective transition into the secondary school tracks contributes to the general deterioration of the mean reading literacy when controlling for social origin and individual achievement. The socially selective transition from primary to secondary school contributes to the increase of social inequality of reading literacy existing already since the start of the pupils’ schooling. Since it is not possible to isolate these causes with comparative-static cross-sectional data like PIRLS or PISA empirically, we use a design of generating quasi-longitudinal data with three time references, namely reading literacy at the point of enrolment into elementary school, at the age of 9–10 years, and at the age of 15 years by the pair wise matching of “synthetic twins” with identical status criteria. The empirical analysis of the German data of PISA 2000 and PIRLS 2001 confirm the effects of the individual abilities depending on social origin, the social selectivity of transition into the secondary schools, the sorting and selection performances of the school system, the allocation of children into different learning contexts, and the schooling of both the individual development of reading competences and the social inequality of reading literacy.