Suspended Particles Research Articles

Eddy-driven diazotroph distribution in the subtropical North Atlantic: horizontal variability prevails over particle sinking speed

Mesoscale eddies influence the distribution of diazotrophic (nitrogen-fixing) cyanobacteria, impacting marine productivity and carbon export. Non-cyanobacterial diazotrophs (NCDs) are emerging as potential contributors to marine nitrogen fixation, relying on organic matter particles for resources, impacting nitrogen and carbon cycling. However, their diversity and biogeochemical importance remain poorly understood. In the subtropical North Atlantic along a single transect, this study explored the horizontal and vertical spatial variability of NCDs associated with suspended, slow-sinking, and fast-sinking particles collected with a marine snow catcher. The investigation combined amplicon sequencing with hydrographic and biogeochemical data. Cyanobacterial diazotrophs and NCDs were equally abundant, and their diversity was explained by the structure of the eddy. The unicellular symbiotic cyanobacterium UCYN-A was widespread across the eddy, whereas Trichodesmium and Crocosphaera accumulated at outer fronts. The diversity of particle-associated NCDs varied more horizontally than vertically. NCDs constituted most reads in the fast-sinking fractions, mainly comprising Alphaproteobacteria, whose abundance significantly differed from the suspended and slow-sinking fractions. Horizontally, Gammaproteobacteria and Betaproteobacteria exhibited inverse distributions, influenced by physicochemical characteristics of water intrusions at the eddy periphery. Niche differentiations across the anticyclonic eddy underscored NCD-particle associations and mesoscale dynamics, deepening our understanding of their ecological role and impact on ocean biogeochemistry.

Fluid-structure interaction of flexible collectors affects particle capture efficiency at ecologically relevant collector Reynolds numbers

Introduction: The capture of suspended particles, which is an important process in many aquatic and terrestrial ecosystems, has been modeled using stationary rigid collectors and, more recently those that move in response to flow-induced vibrations. These models do not, however, account for collector flexibility, despite the fact that many biological collectors, especially aquatic collectors, exhibit flexibility.Methods: This study examined the effect of collector flexibility (indicated by the Young’s Modulus, E; range = 10–3–102 GPa) on particle capture efficiency (η; flux of captured particles: flux of particles) at different collector Reynolds numbers (Rec where the collector diameter [dc] is the length scale; range = 30–508) in a recirculating flow chamber.Results: Patterns in η were generally similar for flexible and rigid collectors until moderate Rec (∼374) when higher η were observed on the most flexible collectors. This threshold corresponded to periods of vortex induced motions in which the oscillation frequency of the collector transverse to the flow direction was >4 Hz and the maximum amplitude of the oscillation relative to dc was >60% in the transverse and >100% in the longitudinal direction.Discussion: Given the range in E examined in this study, it is likely that particle capture on flexible natural collectors has been underestimated using the standard model of a rigid stationary or oscillating collector. The role of collector flexibility should be considered in models and studies of particle capture in natural systems.

Green determination of glucocorticoids in water environment based on novel polydopamine coated iron tetroxide via magnetic dispersive solid phase microextraction

As the potential risks on human and aquatic animal exposed to the glucocorticoids in environment, it is essential to detect anti-epidemic pharmaceutical in real water samples. In this work, a core-shell shape, magnetic suspension particle sorbents of Fe3O4@oleic acid@polydopamine (Fe3O4@OA@PDA) were synthesized for magnetic dispersive solid phase microextraction (MDSPME), which possessed considerable dispersibility in water samples and extracted three glucocorticoids through hydrogen bonding with high detection sensitivity. The adsorption process of MDSPME was investigated by thermodynamic and kinetic theory, which demonstrated that the kinetic processes of adsorption were in accordance with the quasi second order kinetic model, and the adsorption isotherm was in accordance with the Freundich model. Combined with high performance liquid chromatography-Ultraviolet spectrophotometer detector, the proposed method had a linear range of 5–200 μg/L with an ultra-low detection limit down to 0.5–1.1 μg/L. The Green Analytical Greenness Metric (AGREE) software was employed to evaluate the greenness of the analytical method. This work presented an effective strategy for creating ultrasensitive and cost-effective probe for detection in anti-epidemic drugs.

Dynamic characteristics of suspended particles influenced by cavitation bubble in a free field

This study investigates the dynamic characteristics of suspended particles in a free field under the influence of a single cavitation bubble. The phenomenon of suspended particles being influenced by cavitation bubbles of comparable size reflects the dynamic characteristics of particles, a common occurrence in both hydraulic machinery and biopharmaceutical fields. A high-speed camera captures the process of a single cavitation bubble interacting with suspended particles. Combined with three-dimensional numerical simulations, the motion states of suspended particles as the cavitation bubble expands and contracts are analyzed. Observations reveal that at various initial distances between suspended particles and the cavitation bubble, suspended particle motion is consistently influenced by the expansion and contraction of the same cavitation bubble during the initial four processes. The particle motion direction is parallel to the propagation direction of the radiation force produced during the expansion and collapse of the cavitation bubble, consistent with the characteristics of motion under longitudinal wave effects. The initial distance between suspended particles and the cavitation bubble dictates the ultimate displacement direction of suspended particles, with the influence of the cavitation bubble on suspended particle velocity weakening as their distance increases. Under conditions where particle size closely matches that of the bubble, the jet produced by the cavitation bubble does not significantly accelerate particles, and the influence of the jet on suspended particle motion states could be disregarded. The investigation reveals that the suspended particles are primarily influenced by the radiation force, drag force, and virtual mass force exerted by the cavitation bubble.

Lattice Boltzmann simulation on particle suspensions containing porous particles in a narrow channel

The suspension of porous particles in fluids occurs widely in various natural and industrial processes. However, the sedimentation behavior of porous particles is not extensively understood as the solid impermeable counterparts. In this work, the drafting–kissing–tumbling (DKT) phenomenon in a narrow channel containing porous particles is investigated by the multi-relaxation-time (MRT) lattice Boltzmann method (LBM). The initial particle spacing Lp* (1.5∼6) and Darcy number Da (8×10−6∼6×10−2) are examined on the sedimentation process of two particles under three initial arrangements, i.e., the trailing particle is porous (case 1), the leading particle is porous (case 2), and both the particles are porous (case 3). The results show that the presence of porous particles can enhance the interactions between two particles, and increasing the penetrability reduces the particle drag force to accelerate sedimentation. The drafting time is insensitive to Da at small Lp*, and it decreases with Da at large Lp* in cases 1 and 3 while it changes to increase with Da in case 2. A phase diagram with respect to Da and Lp* is further extracted to identify three sedimentation modes of particle pairs. It is found that the transition between the one-off DKT and repeated DKT modes is not affected by Lp* in cases 2 and 3, while the critical condition for the non-DKT and one-off DKT modes depends strongly on Da and Lp* in case 2.

Revisiting the governing equations of a magnetic suspension of polar particles: From microhydrodynamics analysis to rheological response

In this review, we describe a formulation for the stress tensor of a monodisperse magnetic suspension of polarized neutrally buoyant spheroidal particles suspended in a non-magnetic liquid. A magnetic suspension affords a rare example of a material for which the stress tensor is non-symmetric. The present formulation is based on a microhydrodynamics description of a spherical particle suspended in a Newtonian fluid subjected to magnetic forces and torques. The magnetic suspension is considered statistically homogeneous and treated as being a homogeneous equivalent fluid. Under this condition, a volume average over all particles in the carrier fluid is used in order to obtain the magnetization equation evolution and the constitutive equation for the stress tensor of the magnetic suspension, in particular the magnetic stress contribution. The average effects on the homogeneous continuum fluid due to particle pressure, particle dipole, and the applied magnetic field on each particle are computed by our constitutive equation. In this approach, the particles are not considered force or torque free since their permanent magnetization allows them to experience the effects of an applied magnetic field. The calculated stress tension can be used for modeling common flows of symmetric or non-symmetric magnetic fluids flowing in arbitrary geometries and in rheological applications for determination of important properties such as the rotational viscosity of non-symmetric magnetic fluids. The final expression of the constitutive equation for the stress tensor based on a particle scale approach presents some difference as compared with current constitutive models proposed in the current literature. Our constitutive equation considers the effect of a magnetic particle pressure, the average particle stresslet contribution in terms of an effective viscosity, the average particle rotlet in terms of a rotational viscosity, and a configurational tensor associated with dipole–dipole interactions. In addition, we discuss the situation in which the dipole moment of the particle is not frozen on it which leads to the necessity of an internal balance of angular momentum in a fluid element to close the governing equations of the model. An extension of the model for emulsions of polar deformable droplets is also proposed.

Modeling the evaporation and drying of two-component slurry droplets

In this paper, we present a mathematical model and numerical simulation for the evaporation and drying of a liquid droplet containing suspended solids, relevant to processes such as spray drying and spray pyrolysis in the food and pharmaceutical industries. The model comprises three stages: first is the evaporation of the liquid droplet consisting of solid particles, followed by the second stage starting with the formation of a porous crust around a wet-core region and, finally, the third stage with sensible heating of the dry particle. Using a finite difference method with a moving grid, we account for the moving interface between the crust and wet core. Our model incorporates spatial temperature variations and is validated against experimental data on colloidal silica droplet drying, showing good agreement. We examine model assumptions and analyze the impact of drying conditions on drying rate and final particle morphology. Along with the temperature and velocity of the drying gas, we also find that the shape of suspended solid particles inside the droplet and assuming continuum flow of vapor through the crust influence drying quality. Finally, we develop a regime map to predict whether the final particle will be solid or hollow based on operating conditions.

Hydrodynamic Impact of Dusty Fluid-Suspended Solid Particles in a Single-Walled Corrugated Channel for Water-Curing Infrastructure Networks

Infrastructure engineering is impacted by solid particles in fluids, and engineering components are influenced by fluid flow methods. This work explores the effects of dusty fluids with suspended solid particles in a single-walled corrugated channel using electromagnetic hydrodynamics. Potential, continuity, and momentum equations were employed to study the periodic sinusoidal waves in the corrugations of two wavy walls using the perturbation method. We assessed the impact of corrugation on velocity for EMHD fluid flow using mathematical computation, concentrating on the analytical velocity solutions. The analysis of velocity profiles through graphs reveals that corrugation affects fluid and particle velocity behavior, with small amplitude reducing wave effects and dusty particles boosting velocity. The proposed model uses mathematical induction to solve engineering problems using corrugated wall conditions for fluid control during curing stages. It may be valuable for sanitation networks, rainwater drainage networks, and irrigation systems. In the end, a thorough examination of the obtained results and information from past papers demonstrated a high level of agreement. Additionally, its use in the curing of water will offer alternative methods of managing the flowing fluid than mechanical pressure.

Stability of plane parallel flow revisited for particle-fluid suspensions

Abstract An alternative model is proposed for hydrodynamic stability of plane parallel flow of an incompressible Newtonian fluids with suspended solid particles. For heavy particle-laden dusty gases with negligible particle volume fraction, the effective complex-form mean velocity in the modified Orr-Sommerfeld equation derived by the present model is showed to be essentially identical to the well-known Saffman's classical results. In the limit cases of small or large Stokes number of particles, simple formulas are derived for the effective Reynolds number ratio of the particle-laden suspension to the clear fluid without particles under otherwise identical conditions. The derived formula for particles of finite particle-to-fluid density ratio and small Stokes number is verified by comparing predicted results with known data, although a comparison of the derived formula with known results for particles of finite density ratio and large Stokes number cannot be made here due to the lack of available data. It is hoped that the present work could offer a conceptually novel and relatively simplified model for hydrodynamics of solid particle-fluid suspensions.

Micro-encapsulated phase change material suspensions for heat and mass transfer: A thermo-physical characterization

Despite the growing popularity of phase change materials (PCM) and suspensions of micro-encapsulated phase change materials (mPCM) in both industrial and scientific applications, their properties characterization remains partial and mainly limited to thermal properties. The characterization of such suspension is a crucial aspect for comprehending their behavior and optimizing their performance. This paper is dedicated to a wide characterization of two suspensions containing micro-encapsulated phase change material. In pursuit of a thorough understanding, we also extend our characterization efforts to the bulk PCM encapsulated within the particles.Our primary focus is on determining the materials thermal properties such as latent heat and specific heat capacity using differential scanning calorimetry. Different cooling and heating rates have been employed in our measurements. Regarding our experiments, the bulk phase change material is predominantly identified as octadecane. Results obtained from calorimetry are then compared between the bulk PCM and the mPCM suspensions. By comparing the magnitudes of latent heat obtained for suspensions with the bulk material, we can accurately determine the mass fraction of PCM within each suspension. Noteworthy, during the solidification process an additional latent heat peak is observed only for the encapsulated PCM.The density of the materials is also measured. The phase change of PCM included in the capsules can be observed in densimetry: within the studied temperature range (283.15–306.15 K), the most significant density variations occur during intervals associated with phase change transitions. In ranges where the PCM, included in the capsules, is in a single-phase state (solid/liquid), we provide linear laws that account for density variations with temperature.Finally, our characterization work focuses on the rheological properties of the materials. While the bulk PCM in liquid phase exhibits a Newtonian viscosity, mPCM suspensions present a non-Newtonian viscosity. Both shear-thinning and shear-thickening behaviors are observed depending on the suspension particle volume fraction ϕ of mPCM. This paper concludes with a full comparison of our characterization results with models and correlations proposed in the literature.

Wildfires Influence Mercury Transport, Methylation, and Bioaccumulation in Headwater Streams of the Pacific Northwest.

The increasing frequency and severity of wildfires are among the most visible impacts of climate change. However, the effects of wildfires on mercury (Hg) transformations and bioaccumulation in stream ecosystems are poorly understood. We sampled soils, water, sediment, in-stream leaf litter, periphyton, and aquatic invertebrates in 36 burned (one-year post fire) and 21 reference headwater streams across the northwestern U.S. to evaluate the effects of wildfire occurrence and severity on total Hg (THg) and methylmercury (MeHg) transport and bioaccumulation. Suspended particulate THg and MeHg concentrations were 89 and 178% greater in burned watersheds compared to unburned watersheds and increased with burn severity, likely associated with increased soil erosion. Concentrations of filter-passing THg were similar in burned and unburned watersheds, but filter-passing MeHg was 51% greater in burned watersheds, and suspended particles in burned watersheds were enriched in MeHg but not THg, suggesting higher MeHg production in burned watersheds. Among invertebrates, MeHg in grazers, filter-feeders, and collectors was 33, 48, and 251% greater in burned watersheds, respectively, but did not differ in shredders or predators. Thus, increasing wildfire frequency and severity may yield increased MeHg production, mobilization, and bioaccumulation in headwaters and increased transport of particulate THg and MeHg to downstream environments.

Highly Porous Particles of Cellulose Derivatives for Advanced Applications.

А chemical modification of cellulose diacetate by phthalate and nitrate was performed to increase solubility in organic solvents and change the electrical properties. The role ofsubstituentson the conductivity, permittivity, and polarizability of cellulose films is revealed. It has been shown that highly porous micro particles can be obtained from cellulose derivatives by a simple and technological freeze-drying method. The resulting micro sized aerogels have a predominantly spherical morphology and amorphous structure. Suspensions of porous particles of nitro- and phthalylated cellulose derivatives in silicone oil have an increased dielectric permittivity compared to cellulose diacetate particles. Produced particles are novel promising material with tunable electrical properties for advanced applications in composites, including for electrorheological fluids.

Validation of the method for determining priority phthalates by GC-MS at trace concentrations in surface water with a background pollution level

A methodology for determining priority phthalates (PP) at trace concentrations in surface waters with a background pollution level has been validated. Lake Baikal, the largest natural reservoir that retains up to 20% of the world’s fresh surface waters, was chosen as a natural model for the study. Baikal is characterized by a minimal content of suspended organic matter, a low degree of mineralization and a background level of organic pollutants. Four priority phthalates were found in Baikal water: dimethyl phthalate, diethyl phthalate di-n-butyl phthalate and di-(2-ethylhexyl) phthalate present in the concentration range from 0.01 to 0.66 μg/liter. The method for phthalate determination includes a single liquid-liquid extraction of phthalates (Vsample = 1 liter) and direct analysis of the extracts by GC-MS. Considering the minimum content of suspended particles in water and the use of high sensitivity of the mass spectrometry, the stages of sample filtration and concentration of extracts are excluded from the procedure. Deuterated phthalates are used as surrogate internal standards for the quantitative determination of priority phthalates. The laboratory background of phthalates was assessed using reagent-blank methods, exhaustive multiple extraction and subsequent exclusion of the resulting value from the determination result as a systematic error. The limits of phthalate determination (0.01 – 0.17 μg/liter) and the error of determination (±δ from 12 to 38%) were assessed in the concentration range from 0.01 to 0.66 μg/liter. The method was validated during monitoring of persistent organic pollutants in water of Lake Baikal for the period 2015 – 2023.

A Level-Set/FEM approach for particle bed growth in Stokes–Darcy suspension filtration

This article presents an innovative approach to modeling particle bed growth through suspension dead-end filtration, a process of paramount importance in various industrial and environmental contexts. More precisely, it focuses on the numerical formulation of a continuous approach based on a Stokes–Darcy coupling. In a Level-Set/FEM frame, this model effectively captures the dynamic evolution of particle beds (cake), taking into account the interaction between suspended particles and porous media. Model validation is also a key focus of this paper. Numerical tests are carried out under various conditions, and their results are compared with analytical solutions and experimental data drawn from the literature. This permits corroboration of the predictive capabilities of the model, confirming the robustness and accuracy of the proposed approach. Firstly, Stokes–Darcy coupled flows are investigated in simplified cases such as rectangular geometries and coaxial cylinders. These scenarios serve as benchmarks to assess the model performance under simple and varied conditions. Additionally, the more challenging case of a three-dimensional anisotropic flow between two ellipsoids is addressed, where the evolution of the cake takes place in three dimensions. Through rigorous analysis and comparison with analytical solutions, the model is proved efficient in capturing the inherent complexities of such scenarios. Finally, richer two-dimensional Stokes–Darcy flows are considered, in the presence of both impermeable and permeable obstacles, representing a crucial step towards modeling real industrial processes. This last study highlights not only the formation of particle-free zones but also the practical relevance of this work.

Status of the transfer state of 137Cs in zooplankton and surface water fish off Fukushima during 2018–2021

Radiocaesium introduced to coastal waters by the accident at the Fukushima Dai-ichi Nuclear Power Station (F1NPS) elevated the radioactivity level in biota. The radionuclide level in zooplankton, concentration of 137Cs radioactivity in surface water fish decreased rapidly, which was the primary food source for planktivorous fish, was recognized as not to be depurated at the same level prior to the accident. To evaluate the possible cause of this phenomenon, zooplankton and surface water fish were collected off Fukushima during 2018–2021, and the presence of radioactive particles was also examined. The concentrations of stable Cs and 137Cs radioactivity were analysed along with aluminium which was an indicator element of Cs that originated from suspended particles which were attached to or ingested by zooplankton. As a result, radioactive particles were often found in coastal zooplankton samples, and stable Cs and 137Cs of this inorganic fraction were identified. After removal of this excess radioactivity, the 137Cs radioactivity in whole-body tissue of zooplankton was derived. However, the level in the soft part of zooplankton during 2018–2020 was still greater than the levels which existed before 2010. Since habitat seawater was understood to not be a substantial source of 137Cs, then 137Cs transfer along the food chain, possibly from phytoplankton or detritus of enhanced radioactivity were suggested as important sources of 137Cs. In addition, enhanced 137Cs radioactivity in zooplankton was considered consequently elevate radioactivity levels in surface-dwelling water fish off Fukushima. Although the radioactivity level was not radiologically significant in relation to seafood safety limit, enhanced 137Cs radioactivity levels in biota was demonstrated in southern waters off Fukushima. In contrast, derived 137Cs/133Cs atom ratios of fish and seawater south of 37°E and west from 142°E indicated that radiocaesium transfer between fish and the environment was in an equilibrium state, showing the environment beyond these geographical coordinates had returned to the pre-accident state.

Turbulent pipe flow with spherical particles: Drag as a function of particle size and volume fraction

Suspensions of finite-size solid particles in a turbulent pipe flow are found in many industrial and technical flows. Due to the ample parameter space consisting of particle size, concentration, density and Reynolds number, a complete picture of the particle–fluid interaction is still lacking. Pressure drop predictions are often made using viscosity models only considering the bulk solid volume fraction. For the case of turbulent pipe flow laden with neutrally buoyant spherical particles, we investigate the pressure drop and overall drag (friction factor), fluid velocity and particle distribution in the pipe. We use a combination of experimental (MRV) and numerical (DNS) techniques and a continuum flow model. We find that the particle size and the bulk flow rate influence the mean fluid velocity, velocity fluctuations and the particle distribution in the pipe for low flow rates. However, the effects of the added solid particles diminish as the flow rate increases. We created a master curve for drag change compared to single-phase flow for the particle-laden cases. This curve can be used to achieve more accurate friction factor predictions than the traditional modified viscosity approach that does not account for particle size.

Air quality assessment of poultry and swine houses in Chonburi Province

ABSTRACT The increased consumption of animal products has led to a proliferation of animal husbandry operations, particularly in agricultural countries. Animal husbandry facilities or livestock farming directly impact the physical, chemical, and biological aspects of the environment, giving rise to various issues such as odors, contamination of water and air sources with pathogens, and potential contamination of meat products originating from these facilities. This research aims to assess the impacts on the physical (temperature, relative humidity and air velocity), chemical (carbon dioxide, total volatile organic compounds and particulate matter), and biological air quality assessment (amount and type of bioaerosols) aspects resulting from pig and poultry farming. The findings will serve as valuable data for managing and addressing these aforementioned issues. It was found that both in poultry and swine houses generated total suspended particles (TSP) and PM10 (Particulate Matter with a diameter of 10 µm or less). Analysis of poultry house exhaust revealed elevated concentrations of TSP and PM10 exceeding established health benchmarks. Chickens tend to produce a higher concentration of VOCs (2.07 ± 0.57 ppm) compared to swine (0.82 ± 0.53 ppm). Staphylococcus epidermidis was predominant bacteria in both swine and poultry houses while Cladosporium sp was the most prevalent fungi in poultry houses. These results in this study are very useful for developing targeted mitigation strategies, products, devices to address specific pollutants produced by each type of livestock, reducing overall environmental impact and improving air quality within and around animal husbandry facilities. Implications: This research highlights how the growing demand for meat is affecting the environment, especially in farming areas. By studying the effects of pig and poultry farming on things like air and water quality, the study shows the challenges these farms pose, like bad smells and pollution. They found that both types of farms release a lot of tiny particles and smelly chemicals into the air, but there are differences between them. Understanding these findings can help us develop ways to reduce the pollution from these farms and make the air cleaner for everyone.

Rheological Behavior of an Aqueous Suspension of Oxidized Carbon Nanohorn (CNHox).

Oxidized carbon nanohorn (CNHox) a carbon nanomaterial that has attracted attention due to its unique material properties. It is expected to be applied in various areas like cancer treatment, gene-expression technology, fluids with high thermal conductivity, lubricants, and so on. While the rheological measurements of suspensions provide information on the effective size and interactions of suspended particles, the rheological behaviors of aqueous suspensions of CNHox have never been systematically investigated. To clarify the rheological behaviors of aqueous suspensions of CNHox, their viscosity and dynamic viscoelasticity were measured with changing particle concentration and salt concentration. The viscosity of a CNHox suspension showed yield stress at low shear rates and showed shear-thinning behavior with increasing shear rates. The viscosity of 5 weight % CNHox suspensions was comparable to that of 60 weight % silica suspensions. This high viscosity at a low CNHox concentration is probably due to the porous structure and large effective volume of the CNHox particle. The estimated effective volume of CNHox calculated by the Krieger-Dougherty equation was 18.9 times larger than the actual volume calculated by the mass concentration and density. The dependence of rheological behavior of the CNHox suspension on salt concentration was weak compared to that of the colloidal silica suspension. This weak dependence on salt concentration may be due to the roughness of the particle surface, which would weaken the effect of electric double-layer interactions and/or van der Waals interactions between particles. These rheological behaviors of the aqueous suspension of CNHox shown in this research will be useful in efforts to improve the efficiency of its utilization for the various applications.

Oligo cyc-DEP: On-chip cyclic immunofluorescence profiling of cell-derived nanoparticles.

We present a follow-on technique for the cyclic-immunofluorescence profiling of suspension particles isolated using dielectrophoresis. The original lab-on-chip technique ("cyc-DEP" [cyclic immunofluorescent imaging on dielectrophoretic chip]) was designed for the multiplex surveillance of circulating biomarkers. Nanoparticles were collected from low-volume liquid biopsies using microfluidic dielectrophoretic chip technology. Subsequent rounds of cyclic immunofluorescent labeling and quenching were imaged and quantified with a custom algorithm to detect multiple proteins. While cyc-DEP improved assay multiplicity, long runtimes threatened its clinical adoption. Here, we modify the original cyc-DEP platform to reduce assay runtimes. Nanoparticles were formulated from human prostate adenocarcinoma cells and collected using dielectrophoresis. Three proteins were labeled on-chip with a mixture of short oligonucleotide-conjugated antibodies. The sample was then incubated with complementary fluorophore-conjugated oligonucleotides, which were dehybridized using an ethylene carbonate buffer after each round of imaging. Oligonucleotide removal exhibited an average quenching efficiency of 98±3% (n=12 quenching events), matching the original cyc-DEP platform. The presented "oligo cyc-DEP" platform achieved clinically relevant sample-to-answer times, reducing the duration for three rounds of cyclic immunolabeling from approximately 20 to 6.5h-a 67% decrease attributed to rapid fluorophore removal and the consolidated co-incubation of antibodies.

Insight into the mechanism of adsorption and release of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol in sewage by modeling regional suspended particles for evaluation of the influence on monitoring of cannabis illicit abuse

The adsorption of 11-nor-9-carboxy-∆9-tetrahydrocannabinol (THC-COOH) by the suspended particles in sewage makes it fail to accurately monitor cannabis abuse. In this work, the model sewage sample was prepared through equivalent mixing the sewage from 10 different sewage treatment plants in Guangdong province of China and used as a comprehensive representative for investigating the adsorption and release behavior of THC-COOH on the suspended particles under different temperature and pH. The solid-liquid distribution of THC-COOH in sewage depended strongly on the adsorption and release properties which were susceptible to the temperature and pH, specially adjusting pH to 11.0 could release more than 90 % of THC-COOH from the suspended particles. By means of the kinetics models, pseudo-second-order kinetic and Weber-Morris models revealed the mechanism of adsorption and release of THC-COOH in sewage that was a relatively reversible and controllable process with multiple interactions, and then it was further confirmed by the validation experiment in a variety of actual sewage samples. According to the suggested pH, the modification of the existing detection protocol prior to high performance liquid chromatography-tandem triple quadrupole mass spectrometry (HPLC-TQ-MS/MS), was successfully applied to determination of THC-COOH in the stimulated positive samples, and the recoveries and RSDs were respectively 95.48–99.79 % and 4.0–5.6 %. The finding could greatly help improving the accuracy of not only the detection of THC-COOH in sewage but also the estimation data of the consumption level of cannabis in the related regions.