Solid Phase Research Articles

An aberrant fused in sarcoma liquid droplet of amyotrophic lateral sclerosis pathological variant, R495X, accelerates liquid–solid phase transition

Intracellular aggregation of fused in sarcoma (FUS) is associated with the pathogenesis of familial amyotrophic lateral sclerosis (ALS). Under stress, FUS forms liquid droplets via liquid–liquid phase separation (LLPS). Two types of wild-type FUS LLPS exist in equilibrium: low-pressure LLPS (LP-LLPS) and high-pressure LLPS (HP-LLPS); the former dominates below 2 kbar and the latter over 2 kbar. Although several disease-type FUS variants have been identified, the molecular mechanism underlying accelerated cytoplasmic granule formation in ALS patients remains poorly understood. Herein, we report the reversible formation of the two LLPS states and the irreversible liquid–solid transition, namely droplet aging, of the ALS patient-type FUS variant R495X using fluorescence microscopy and ultraviolet–visible absorption spectroscopy combined with perturbations in pressure and temperature. Liquid-to-solid phase transition was accelerated in the HP-LLPS of R495X than in the wild-type variant; arginine slowed the aging of droplets at atmospheric conditions by inhibiting the formation of HP-LLPS more selectively compared to that of LP-LLPS. Our findings provide new insight into the mechanism by which R495X readily forms cytoplasmic aggregates. Targeting the aberrantly formed liquid droplets (the HP-LLPS state) of proteins with minimal impact on physiological functions could be a novel therapeutic strategy for LLPS-mediated protein diseases.

Microbial hydrogen sinks in the sand-bentonite backfill material for the deep geological disposal of radioactive waste.

The activity of subsurface microorganisms can be harnessed for engineering projects. For instance, the Swiss radioactive waste repository design can take advantage of indigenous microorganisms to tackle the issue of a hydrogen gas (H2) phase pressure build-up. After repository closure, it is expected that anoxic steel corrosion of waste canisters will lead to an H2 accumulation. This occurrence should be avoided to preclude damage to the structural integrity of the host rock. In the Swiss design, the repository access galleries will be back-filled, and the choice of this material provides an opportunity to select conditions for the microbially-mediated removal of excess gas. Here, we investigate the microbial sinks for H2. Four reactors containing an 80/20 (w/w) mixture of quartz sand and Wyoming bentonite were supplied with natural sulfate-rich Opalinus Clay rock porewater and with pure H2 gas for up to 108 days. Within 14 days, a decrease in the sulfate concentration was observed, indicating the activity of the sulfate-reducing bacteria detected in the reactor, e.g., from Desulfocurvibacter genus. Additionally, starting at day 28, methane was detected in the gas phase, suggesting the activity of methanogens present in the solid phase, such as the Methanosarcina genus. This work evidences the development, under in-situ relevant conditions, of a backfill microbiome capable of consuming H2 and demonstrates its potential to contribute positively to the long-term safety of a radioactive waste repository.

Phase field-volumetric lattice Boltzmann model of ion uptake in porous nuclear waste form materials under continuous flow

The flow field within the mesopores of sorbent particles plays a crucial role in radionuclide diffusion and ion uptake kinetics, thus, impacting the overall performance of porous nuclear waste form materials. To fundamentally understand the influence of microstructures and material properties on the radionuclide absorption and retention processes requires a coupled multi-physics model that considers the advection and diffusion within the flow field, the reaction at liquid-solid interfaces, and finally, the solid-state diffusion within a complex nanoporous medium. This study employs the volumetric lattice Boltzmann method (VLBM) to accurately and efficiently calculate the steady state velocity field inside the mesopores of sorbent particles. The obtained velocity field is then utilized to calculate the advection of ions in the steady flow. A phase field (PF) model of ion uptake is used to describe the reaction occurring at the solid-liquid interface and diffusion inside the porous medium. The integrated PF-VLBM model is verified in terms of the mass conservation and numerical efficiency and validated qualitatively with experimental observation data. Then, it is applied to study the influence of thermodynamic and kinetic properties, as well as flow field conditions on the ion uptake kinetics. The numerical results demonstrate that the ion uptake kinetics in porous particles has three distinct stages, which is in agreement with the observations in continuous flow experiments. In the first stage, the kinetics is predominantly controlled by the flow field and ion diffusivity in the liquid phase. The kinetics in the second stage is primarily governed by ion diffusivity in the solid phase. In the third stage the system reaches a dynamic equilibrium with a net zero uptake flux at the interface. It is also found that porous structures significantly affect the efficiency and capacity of ion uptake. The simulation results can help to understand the physics behind the observed ion uptake kinetics in experiments and to facilitate the development of constitutive equations that can account for heterogeneous microstructures in engineering performance codes.

A layered aerogel composite with silica fibers, SiC nanowires, and silica aerogels ternary networks for thermal insulation at high-temperature

Due to excellent thermal insulation performance at room temperature and ultralow density, silica aerogels are candidates for thermal insulation. However, at high temperatures, the thermal insulation property of silica aerogels decreased greatly caused by transparency to heat radiation. Opacifiers introduced into silica sol can block heat radiation yet destroy the uniformity of aerogels. Herein, we designed and prepared a silica aerogel composite with oriented and layered silica fibers (SFs), SiC nanowires (SiCNWs), and silica aerogels, which were prepared by papermaking, chemical vapor infiltration (CVI), and sol-gel respectively. Firstly, oriented and layered SFs made still air a wall to block heat transfer by the solid phase. Secondly, SiCNWs were grown in situ on the surface of SFs evenly to weave into the network, and the network reduced the gaseous thermal conductivity by dividing cracks in SFs/SiCNWs/SA. Thirdly, SiCNWs weakened the heat transfer by radiation at high temperatures. Therefore, SFs/SiCNWs/SA presented remarkable thermal insulation (0.017 W (m K)–1 at 25 °C, 0.0287 W (m K)–1 at 500 °C, and 0.094 W (m K)–1 at 1000 °C). Besides, SFs/SiCNWs/SA exhibited remarkable thermal stability (no size transform after being heat treated at 1000 °C for 1800 s) and tensile strength (0.75 MPa). These integrated properties made SFs/SiCNWs/SA a promising candidate for highly efficient thermal insulators.

Numerical investigation and optimisation of solid–solid phase change material composite-based plate-fin heat sink for thermal management of electronic package

Phase Change Material based Thermal Management Systems show promise in electronic packaging systems for safe operation, acting as a thermal storage element to prevent sudden temperature surges, enhancing operational time and mitigating electronic system failures. Therefore, the meticulous design of a solid–solid phase change material (SSPCM) based heat sink with fins is imperative for effective electronic thermal management by improving its safe operational time. This study performs a numerical analysis of two-dimensional transient heat transfer for the SSPCM-based plate-fin heat sink using the modified enthalpy porosity method, where the plate fins serve as Thermal Conductivity Enhancers (TCEs). Neopentyl glycol with 6% (w/w) Copper oxide nanoparticle is used as the SSPCM composite. Enhancement ratio based on safe operational time at different power levels (2–6 W) with different percentages of TCE and fin count recorded variation from 1.32 to 13.7. The TCE integration is more effective at higher power levels. The optimisation of SSPCM-based heat sink design for maximum safe operational time is accomplished through Response Surface Methodology. The significance of the TCE fraction, number of fins, heat generation rate, and interaction effects over the safe operational time are observed. The correlation for safe operational time as a function of TCE volume fraction, fin count and heat generation rate is developed. TCE volume fraction possesses the highest influencing factor over safe operational time at lower and higher power levels compared to fin count. At 2 W and 6 W, a maximum change in safe operational time is observed from 72.7% at 2 W to 83.45% at 6 W. The heat sink with 0.262 volume fraction of TCE and 11 fins is the optimised design that can provide the desirable safe operational time for the tested range of power levels.

Master sintering curve analysis of ZnO densified by Cold Sintering Process

The Master Sintering Curve (MSC) model is traditionally used to describe the densification kinetics of a specific material and allows to determine the activation energy of the dominant mechanism. In this study, this approach is applied to the Cold Sintering Process (CSP) of ZnO with the addition of acetic acid. The result was compared with SPS sintered samples from the same dry powder. The apparent activation energy of the ZnO powder sintered by CSP with acetic acid is 4 times lower than the same dry powder (338 kJ/mol versus 83 kJ/mol). This low value confirms the low energy surface interactions between liquid and solid phases involved in mechanisms of ZnO. MSC model applied to CSP presents different interests to detect similarities or differences in sintering mechanism with different liquid phases. It allows to determine the densification trajectory of the material, then to select the optimum processing parameters to control its microstructure.

Comparative evaluation of liquid-liquid extraction and nanosorbent extraction for HPLC-PDA analysis of cabazitaxel from rat plasma

A precise, sensitive, accurate, and validated reverse-phase high-performance liquid chromatography (RP-HPLC) method with a bioanalytical approach was utilized to analyze Cabazitaxel (CBZ) in rat plasma. Comparative research on extraction recoveries was performed between traditional liquid-liquid extraction (LLE) and synthesized graphene oxide (GO) based magnetic solid phase extraction (GO@MSPE). The superparamagnetic hybrid nanosorbent was synthesized using the combination of iron oxide and GO and subsequently applied for extraction and bioanalytical quantification of CBZ from plasma by (HPLC-PDA) analysis. Fourier- transform infrared spectroscopy (FT-IR), particle size, scanning electron microscopy (SEM), and x-ray diffraction (XRD) analysis were employed in the characterization of synthesized GO@MSPE nanosorbent. The investigation was accomplished using a shim pack C18 column (150 mm×4.6 mm, 5 µm) with a binary gradient mobile phase consisting of formic acid: acetonitrile: water (0.1:75:25, v/v/v) at a 0.8 mL/min flow rate, and a λmax of 229 nm. The limits of detection (LOD) and quantitation (LOQ) have been determined to be 50 and 100 ng/mL for both LLE and SPE techniques. The linearity range of the approach encompassed from 100 to 5000 ng/mL and was found to be linear (coefficient of determination > 0.99) for CBZ. The proposed method showed extraction recovery of 76.8–88.4% for the synthesized GO@MSPE and 69.3–77.4% for LLE, suggesting that the proposed bioanalytical approach was robust and qualified for all validation parameters within the acceptable criteria. Furthermore, the developed hybrid GO@MSPE nanosorbent with the help of the proposed RP-HPLC method, showed a significant potential for the extraction of CBZ in bioanalysis.

Improved preconcentration workflow for organic explosive traces in aqueous samples using solvent-assisted dispersive solid-phase extraction

The present study deals with the development of a solvent-assisted dispersive solid phase extraction method for the extraction of HMX, RDX, and TNT from aqueous samples. Benzophenone and methanol were selected as explosives sorbent and dispersive solvent respectively. Extraction parameters like pH, extraction time, amount of sorbent, volume and type of the disperser solvent and centrifuge time were optimized. Dispersion of 0.5 mL dispersive solution (4% (w/v) benzophenone in methanol) was performed by injection into the 5 mL aqueous sample (pH=7) using a 1.0 mL syringe. After centrifuge, the extracted explosives were analyzed by high performance liquid chromatography with ultraviolet detection (HPLC-Uv). The results indicated that the linear ranges with the correlation coefficients of 0.99 ≤ R2 were 1.6–204.6 μg L−1, 1.4–213.7 μg L−1 and 1.3–225.9 μg L−1 for HMX, RDX and TNT respectively. The limit of detection and limit of quantification obtained for each explosive were: 0.3 μg L−1 and 0.8 μg L−1 for HMX, 0.3 μg L−1 and 0.9 μg L−1 for RDX and 0.2 μg L−1 and 0.7 μg L−1 for TNT. Finally, the practical applicability of the developed method was evaluated for the extraction of some organic explosives in water samples followed their determination by HPLC-Uv.

The Influence of Freezing-thawing on the Properties of Sludge from Water Treatment Facilities and the Prospects for its Disposal

It has been shown that the freezing-thawing method allows a sharp increase in the water-yielding capacity of water treatment sludge (WTS sludge) and leads to an increase in the median particle size of the dispersed phase of sludge. The distribution of bound water types in WTP sludge was studied using thermogravimetry (TG), differential thermal thermogravimetry (DTG), differential scanning calorimetry (DSC) and mass spectrometry of gaseous thermolysis products (MS). It has been established that the release of water and carbon dioxide is completely completed at a temperature of 600°C. The specific surface area of the solid phase of WTP sludge before and after freezing-thawing was determined. The pore size distribution was studied. The BET isotherm of WTP sludge corresponds to mesoporous sorbents.

A zirconium metal–organic framework functionalized with a S/N containing carboxylic acid (MOF-808(Zr)-Tz) as an efficient sorbent for the ultrafast and selective dispersive solid phase micro extraction of chromium, silver, and rhodium in water samples

Metal-organic frameworks (MOFs) are good adsorbents for targeted chemicals with their adjustable properties. Herein, we prepared a zirconium based MOF (MOF-808(Zr)) and functionalized it employing 2-mercapto-4-methyl-5-thiazolacetic acid (MOF-808(Zr)-Tz). The prepared MOFs were characterized by XRD, FTIR, SEM-EDX, TGA, N2 sorption, zeta potential measurements, and elemental analysis. The surface area of MOF-808(Zr)-Tz was 1348 m2/g. Dispersive solid-phase micro-extraction (D-SPµE) method based on MOF-808(Zr)-Tz was firstly developed and applied to the extraction of chromium, silver, and rhodium in waters. The determination of the analytes was done by FAAS. The optimal pH and eluent for analytes were 7.0 and 3 mL of 2 mol L−1 HCl, respectively. The contact times were 1 min for adsorption and 3 min for elution. The LOD and PFs of the D-SPμE for analytes were 2.3 μg L−1 and 13.3 for chromium, 2.1 μg L−1 and 13.3 for silver, and 3.1 μg L−1 and 13.3 rhodium, respectively. The D-SPμE method was verified with analyses of NW-TMDA-54.6 Lake water and SPS-WW1 Batch 114 Wastewater and with spiked dam water, river water, well water, sea water, and wastewater. The recoveries of the analytes changed from 89 to 108 %. The results indicated that the method is selective, simple, effective, and rapid for extracting chromium(III), silver(I) and rhodium(III) in waters.

Determination of 9 fentanyl drugs in environmental water by UHPLC-MS/MS combined with solid phase extraction

In this study, sensitive and selective SPE-UHPLC-MS/MS methods were established and applied to the determination of 9 fentanyl drugs in environmental water, in order to address the lack of research on wastewater-based epidemiology for fentanyl drugs. The methods involved purifying and enriching water samples using homemade PS/DVB-WCX SPE cartridges, followed by UHPLC-MS/MS analysis. In subsequent research, the performance of four SPE cartridges were compared, and the results revealed the superior performance of PS/DVB-WCX in terms of extraction efficiency and matrix removal. Optimized instrument parameters enabled qualitative and quantitative analysis of the 9 fentanyl drugs. For different matrices, two quantitative methods were developed and their correlation coefficient (r2) were all greater than 0.9945. The LODs and LOQs of all analytes were 0.17 ng/L and 0.50 ng/L respectively. Accuracy assessment via spiking standards into environmental water samples showed recoveries ranging from 81.4 % to 109.4 % and 81.6 % to 116.7 % respectively for two methods. The results suggested that the proposed methods were able to meet the needs of 9 fentanyl drugs monitoring in environmental water. Additionally, the greenness assessment of the proposed analytical method was evaluated by three greenness assessment metrics: National environmental methods Index (NEMI), Green analytical procedure Index (GAPI), and Analytical GREEnness metric (AGREE). The results indicate that the established method is environmentally friendly.

Investigation on coupling deposition and plugging of hydrate and wax in gas–liquid annular flow: Experiments and mechanism

The coupling deposition and plugging caused by hydrate formation and wax precipitation during the development of deep water natural gas resources bring new industrial challenges and theoretical difficulty. We designed a single-pass pipeline with two types to investigate deposition behavior and systematically performed the coupling deposition and plugging of hydrate and wax experiments in gas–liquid annular flow. The experimental results illustrate that the single solid phase of hydrate is covered layer sheet deposition, while the coupling solid phase of hydrate and wax is bulk aggregations arch bridge deposition. Meanwhile, the natural eddy zone in reducing pipeline accelerates coupling solid particles deposition. Our finds provided the first knowledge on the double effect that wax crystals inhibit particles adhesion and gel network increases aggregations arch bridge blockage. For the low water content in emulsion system, the gel network provides gathering place for hydrate particles, and the arch bridge structure formed by aggregations accelerates the pipeline blockage. The plugging time is shortened by up to 72.6% with the wax concentration increase from 0 wt% to 3 wt%. For the high water content in emulsion system, the majority of wax crystals adsorbed on the hydrate particles and reduce particles cohesion force, which increase the plugging time. Combined with the microscopic morphology evolution perspective of hydrate particles coupled wax, the coupling deposition of hydrate and wax in gas–liquid annular flow has four stages: gas–liquid flow, coupling solid phase formation, coupling solid phase deposition and sloughing, and coupling solid phase plugging. This study can provide theoretical support and design basis for flow assurance program of deep water gas fields and low temperature natural gas transportation pipelines.

Construction and Demolition Waste Ballast as a Pozzolanic Addition in Binary Cements: Characterization and Thermodynamic Stability

The use of raw materials from the recovery of construction waste is frequent. In this study, the waste is obtained from degraded railway ballast, made up of siliceous minerals. This material is added directly to the mixtures to replace part of the cement, forming a good quality cementitious product. The pozzolanic reaction is studied within the waste/lime system in a solid phase and water system for one year. Reaction products such as stratlingite, layered double hydroxide-type compounds, hydrated tetracalcic aluminate, and gels appear. The formation of stratlingite and gels was favored throughout the reaction. The reaction was monitored, calculating the saturation index.

Preparation and application of halogen-free and efficient Si/P/N-containing flame retardants on cotton fabrics

Cotton fabric is extensively utilized due to its numerous applications, but the flammability associated with cotton fabric poses potential security risks to individuals. A halogen-free efficient flame retardant named poly [(tetramethylcyclosiloxyl spirocyclic pentaerythritol)-piperazin phosphate] (PCPNTSi) was developed to consolidate the fire retardance of cotton fabrics. After PCPNTSi treatment, the limiting oxygen index (LOI) of cotton fabric with 30 % weight gain (CP3) was raised to 32.8 %. In the vertical flammability test (VFT), CP3 has self-extinguished performance with a char length of 8.7 cm. The heat release rate (HRR) of cotton fabric with 20 % weight gain (CP2) is 78.8 % lower than that of pure cotton fabric (CP0). In addition, the total smoke release (TSP) of CP2 is 41.7 % lower than that of CP0, indicating PCPNTSi gives cotton fabric a good capability to inhibit smoke release. Finally, the possible flame retardant mechanism was discussed by the data of scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), Fourier Transform infrared spectroscopy (FT-IR) and thermogravimetric infrared spectroscopy (TG-IR). The results show that PCPNTSi is an intumescent flame retardant acting in both gas phase and solid phase.

Bone char switch on reductive dehalogenation of trichloroethene by series of Fe(II)-bearing minerals: The balance between kinetics and electron efficiency

Fe(II)-bearing minerals might be able to drive the attenuation of chlorinated ethene in soil and groundwater, however, with relatively slow kinetics. In this study, bone char(BC) was selected as an efficient and benign catalyst to prepare composites with three different Fe(II)-bearing minerals (Green rust (GR), Fe(OH)2 and FeS), respectively, for enhanced trichloroethylene (TCE) dehalogenation. The kinetics experiment demonstrated that the presence of BC could effectively switch on the TCE dehalogenation by these solids, while these Fe(II)-bearing minerals alone can barely reduce any TCE. Surprisingly, the Fe(OH)2-BC showed fastest TCE reduction rate, followed by GR-BC and FeS-BC in sequence. Acetylene was confirmed as the major dehalogenation products while other chlorinated byproducts were hardly detected. The electron efficiency (ηe) for TCE reduction was further calculated and compared among these BC amended systems, the results show that the highest ηe value was recorded in GR-BC system as 33.14% with high loading of TCE. Solid phase characterization confirmed that the high loading of amorphous Fe(II) on the BC surface might effectively improve the TCE dehalogenation kinetics, while the well crystallized Fe(II)-bearing minerals would increase the electron efficiency. According to this mechanism, it might be possible to achieve balance between kinetics and electron efficiency. Stress resistance test in real groundwater matrix and life cycle analysis (LCA) was conducted to further verify the application potential of these composites.

Phase Coexistence and Edge Currents in the Chiral Lennard-Jones Fluid.

We study a model chiral fluid in two dimensions composed of Brownian disks interacting via a Lennard-Jones potential and a nonconservative transverse force, mimicking colloids spinning at a given rate. The system exhibits a phase separation between a chiral liquid and a dilute gas phase that can be characterized using a thermodynamic framework. We compute the equations of state and show that the surface tension controls interface corrections to the coexisting pressure predicted from the equal-area construction. Transverse forces increase surface tension and generate edge currents at the liquid-gas interface. The analysis of these currents shows that the rotational viscosity introduced in chiral hydrodynamics is consistent with microscopic bulk mechanical measurements. Chirality can also break the solid phase, giving rise to a dense fluid made of rotating hexatic patches. Our Letter paves the way for the development of the statistical mechanics of chiral particles assemblies.

Occurrence and Removal Efficiencies of Four Antibiotics in Kisii and Kabarnet Waste Water Treatment Plants, Kenya

Background: Antibiotics are presently considered as emerging contaminants with adverse effects in the environment and the population such as the development of antimicrobial resistant genes (ARG) and antimicrobial resistant bacteria (ARB). This study was guided by objective entailing to determine the seasonal occurrences and removal efficiencies of four antibiotics in Kisii and Kabarnet waste water treatment plants in Kenya. 
 Place and Duration of Study: Waste water samples were picked from Suneka wastewater treatment plant in Kisii county and Kabarnet Level V Hospital in Baringo County Kenya in the months of June and December 2020
 Methodology: Multiple samples were picked in Kisii and Kabarnet waste water treatment plants in the months of June and December correspond to the dry and wet seasons in Kenya. Collected waste water samples were centrifuged and filtered with glass microfiber filter papers and subsequently passed through a Solid phase extractor cartridge. High Performance Liquid Chromatography was used for quantification of antibiotics as per international commission for harmonization and subsequently applied for analysis.
 Results: The results revealed that the dry season had higher antibiotic concentrations at 1.29, 0.09, 2.92 and 1.82 µg/l for sulphamethoxazole, trimethoprim, ampicillin and amoxicillin respectively for the Kisii waste water treatment plant and 0.18, 0.05, 1.34 and 0.09 µg/l respectively for Kabarnet waste water treatment plant. During the wet seasons the measured concentrations were 1.11, 0.14, 2.04 and 1.34 µg/l for sulphamethoxazole, trimethoprim, ampicillin and amoxicillin at the Kisii WWTP, and 0.14, 0.06, 1.01 and 0.09 µg/l for Kabarnet WWTP. The removal efficiencies in the WWTPs, ranged from a high of 94 % to a low of 11.11 % depending on the type of antibiotic in both wet and dry seasons.
 Conclusion: Amoxicillin, ampicillin, trimethoprim and sulphamethaxazole were found in both Kisii WWTPs and Kabarnet WWTPs with nearly all antibiotics having a higher concentration of in the dry season than in the wet season. The highest calculated percentage removal was 94.03 % while the lowest calculated percentage removal was 7.14 %. The results suggest that the two WWTPs are effective for the removal of different types of antibiotics.

Development of magnetic matrix solid phase dispersion method for the extraction of crystal violet and rhodamine B from sediments based on magnetic ZIF-8 and a deep eutectic solvent

A magnetic matrix solid phase dispersion (MSPD) method based on magnetic ZIF-8 (SDS@MZIF-8) and a deep eutectic solvent was developed and used to the extraction of crystal violet and rhodamine B in lake sediments. SDS@MZIF-8 was prepared and used as the extraction sorbent and dispersant in MSPD. The magnetic property of MZIF-8 facilitated the recovery of the extraction sorbent after the blending step. Hydrophilic deep eutectic solvents were prepared and used as efficient green dispersing solvents in MSPD. The use of magnetic sorbent in MSPD is simple and fast, eliminating some additional steps commonly used in the classical MSPD and shortening the extraction time. The parameters influencing the extraction efficiency were investigated and optimized. Under the optimized conditions, the intra- and inter-day relative standard deviations were less than 4.9 %. The linearity ranged from 2-400 µg g−1 with coefficients of determination higher than 0.9943. The detection and quantification limits of RB and CV varied between 0.3–0.5 μg g−1 and 1.0–1.8 μg g−1, respectively. Finally, the developed method was applied to the analysis of RB and CV in the sediment samples. The recoveries ranged from 93.2 to 107.3 % and the relative standard deviations ranged from 0.8 to 4.9 %. The results suggest a high potential use of the proposed method to determine the organic pollutants in solid samples. Compared with the conventional MSPD extraction technique, the developed method considerably reduced the sample and solvent consumption, offering important environmental benefits.

Application of continuous magnetic solid phase extraction in the extraction of tetracycline antibiotics from honey samples

This study aimed to develop a continuous magnetic solid phase extraction method in a narrow bore tube for the extraction of tetracycline antibiotics from honey samples before their determination with high performance liquid chromatography–diode array detector. In this work, a magnetic covalent organic framework is used as the sorbent. The extraction method is performed in a narrow bore tube by adding 25 mg of a magnetic sorbent prepared from melamine, barbituric acid, and Fe3O4 into the diluted honey sample solution. By using a magnet, the sorbent is moved up and down through the narrow bore tube for five times to improve extraction efficiency. After adsorption the analytes, they are eluted from the sorbent surface using 2,2–dimethoxypropane under vortexing. Then, by using a magnet, the eluent containing the extracted analytes are taken and evaporated with continuous flow of nitrogen. Finally, the residue containing the enriched analytes is reconstituted in microliter–level of mobile phase and injected into chromatographic system for quantitative analysis. Based on the outcomes, the method demonstrated good linearity (0.37–1000 ng g−1), high enrichment factors (175–203), good extraction recoveries (70–81 %), low LODs (0.11–0.18 ng g−1) and LOQs (0.37–0.60 ng g−1). The proposed method is effectively applied for quantification of tetracyclines in twenty–four honey samples. Considering the results, none of the honey samples was contaminated with the studied antibiotics. Regarding to the above–mentioned analytical advantages of the proposed method, its simplicity and rapidity, and green synthesis of the magnetic sorbent particles, the suggested method can be used as a routine method for the extraction of tetracyclines from honey samples.

Pinning/depinning dynamics of trijunction lines during faceted/nonfaceted eutectic growth

We present an in situ experimental study of decoupled- and coupled-growth patterns in a binary faceted/ nonfaceted (f/nf) eutectic alloy. Real-time optical observation is carried out at low growth velocity V (<0.3μms−1) during directional solidification of the transparent AminoMethylPropaneDiol-Succinonitrile (AMPD-SCN) eutectic in thin samples. On a large scale, the two-phase growth front mostly exhibits irregularly spaced decoupled-growth patterns involving faceted fiber-like AMPD crystals that protrude in the liquid ahead of, and in weak diffusive interaction with the nonfaceted SCN solid. The morphological stability of low-velocity, steady-state decoupled-growth patterns is evidenced. In addition, three types of (f/nf) coupled-growth patterns with fiber-like, tubular (or “hollow”) and C-shaped morphologies, respectively, are identified. New light is cast on the pinning/depinning dynamics of trijunctions at which the two solid phases and the liquid meet in equilibrium. A discussion is initiated on the interplay between the interfacial kinetics of the more or less mobile facets and the solute diffusion field, and on the stability of triple junctions with strongly anisotropic interfaces.