ABSTRACT
Indocalamus plants are low-growing shrubby bamboos with growth advantages, such as high biomass and strong resistance, and they are rich in germplasm resources in southern China. This study conducted soil lead (Pb) stress experiments on Indocalamus latifolius (Keng) McClure (LA), Indocalamus hunanensis B.M. Yang (HU), Indocalamus chishuiensis Y.L. Yang and Hsueh (CH) and Indocalamus lacunosus Wen (LC). Five Pb treatments (0, 500, 1000, 1500 mg·kg-1 Pb, and 1000 mg·kg-1 Pb + 1000 mg·kg-1 ethylenediamine tetraacetic acid (EDTA)) were established. EDTA was applied to explore the tolerance mechanism of different Indocalamus species after absorbing large amounts of heavy metals. The results were as follows: (1) under Pb treatment, the total relative biomass of LA, HU and LC was <100%, whereas the total relative biomass of CH was >100%; (2) after applying EDTA, the bioconcentration coefficient, translocation factor, and free proline content of the four Indocalamus species increased; and (3) the Pb mobility and distribution rates of the underground parts of the four Indocalamus species were consistently greater than those of the aboveground parts. The Pb mobility and distribution rates in the stems increased after applying EDTA, while those in the leaves decreased, as the plants tended to transfer Pb to their stems, which have lower physiological activity than their leaves.
ABSTRACT
In this work, for the performance enhancement of iron hexacyanoferrate, an electrochemically active Mn-doped iron hexacyanoferrate cathode is fabricated via a bottom-up approach. It is found that the pre-treatment of interstitial water and appropriate Mn doping are two keys to achieving higher capacity and higher stability. The interstitial water has a trade-off effect between the alleviation of volume expansion upon Na+ (de)intercalation and the retardation of Na-ion diffusion. The moisture-tailored iron hexacyanoferrate with appropriate Mn doping exhibits a high initial Coulombic efficiency of 94.8%, enhanced capacity and rate performance, and excellent cycling stability. These results benefit from the fact that the extraction/insertion of Na ions from/into the lattice via a solid-solution mechanism correspond to both the slight volume expansion and fast sodium diffusion rate; otherwise, the removal of interstitial water and a higher Mn content might lead to poor cycling stability due to excessive volume expansion resulting from rhombohedral to cubic phase transformation. Finally, the less demand on the control of air humidity for the fabrication of electrodes and the potential for the full cell coupled with hard carbon are also demonstrated, which shows great potential for practical applications.
ABSTRACT
In this study, a strategy based on microfluidic method is developed toward a facile fabrication of phase change material microcapsules with uniform and controllable particle size as well as high encapsulation ratio and thermal stability. N-hexadecane, as a phase change material, was successfully encapsulated by a hybrid shell of poly (methyl methacrylate) and polyurea. The fabrication process includes the following three steps: (1) Formation of oil-in-water droplets with uniform micron size in the microfluidic chip; (2) formation of the first polyurea shell to encapsulate droplets by fast interfacial polymerization when the droplets pass through the coiled transport microchannel; and (3) completion of free radical polymerization of methyl methacrylate inside the microspheres by heating to form the hybrid microcapsule shell. The average size, encapsulation ratio, and phase change enthalpy of microcapsules changed by varying the flow rate of the dispersion phase and raw material composition. The highest melting enthalpy of 222.6 J g-1 and encapsulation ratio of 94.5% of the microcapsule were obtained when the flow rates of the continuous and dispersion fluids were 600 µL min-1 and 24 µL min-1, respectively. It is shown that the phase change material microcapsules were stable after 50 heating/cooling cycles.
ABSTRACT
In this work, using electrochemical active Fe as an ion-exchange element (attack side) and the Na x MnFe(CN)6 slurry with a high solid content (MnHCF) as a template (defensive side), a series of binary hexacyanoferrates are prepared via a simple Mn/Fe ion-exchange process, in which Na x FeFe(CN)6 (FeHCF) and solid solution Na x (FeMn)Fe(CN)6 are concentrated on the shell and the core, respectively. The proportions of the two structures are mainly controlled by the competition between the ion-exchange rate in the bulk material and dissolution-reprecipitation rate. Slowing down the attacking rate, such as the use of a chelating agent complexed with the attacker Fe, is advantageous to form a thermodynamically metastable state with homogeneous distribution of elements since the diffusion of Fe2+ in the solid MnHCF is relatively fast. The shell FeHCF could be adjusted by the dissolution-reprecipitation rate, which is driven by the solubility difference. Adding the chelating agent in the defensive side will promote the dissolution of MnHCF and reprecipitation of FeHCF on the surface. Meanwhile, with the increase of Fe sources, the thickness of the shell FeHCF increases, and correspondingly the content of solid solution decreased due to FeHCF is more stable than solid solutions in thermodynamics. Finally, such a design principle in this case study could also be generalized to other ion-exchange processes. Considering the difference of two components in solubility, the larger difference can make the core/shell structure more clear due to the enhancement of dissolution-reprecipitation route.
ABSTRACT
Fe3O4 nanoclusters have attractive applications in various areas, due to their outstanding superparamagnetism. In this work, we realized a one-step flow synthesis of Fe3O4 nanoclusters, within minutes, through the sequential and quantitative introduction of reactants and modifier in a microflow system. The enhanced micromixing performance enabled a prompt and uniform supply of the modifier oleic acid (OA) for both nanoparticle modification and nanocluster stabilization to avoid uncontrolled modified nanoparticles aggregation. The size of the nanoclusters could be flexibly tailored in the range of 50-100 nm by adjusting the amount of OA, the pH, and the temperature. This rapid method proved the possibility of large-scale and stable production of magnetic nanoclusters and provided convenience for their applications in broad fields.
ABSTRACT
The combination of microstructural units is an effective strategy to improve the micromixing of liquid phase systems, especially viscous systems. However, how the microstructural combination influences micromixing is still not systematically investigated. In this work, the Villermaux/Dushman reaction is used to study the micromixing performance of the viscous system of the glycerol-water in the combination of a T-type micromixer and a micropacked bed. Micromixing performances under various structural parameters and fluid characteristics are determined and summarized, and the micromixing laws are revealed by dimensionless analysis considering the specific spatial characteristics and temporal sequence in the combined microstructures. It achieves good agreement with experimental results and enables guidance for the design and scaling-up of the combined T-type micromixer and micropacked bed towards micromixing intensification in viscous reaction systems.
ABSTRACT
Osteosarcoma ranks first in both morbidity and mortality among primary bone tumors. This study aimed to investigate the effect of up-regulation of PRR11 on the malignancy of osteosarcoma and its clinical significance. The expression, biological function, related pathways of PRR11 in osteosarcoma and its impact on prognosis were explored through the bioinformatics database. After PRR11 was up-regulated, cell proliferation, invasion, migration and apoptosis were detected by the cell counting kit-8 method, Transwell, scratch, and flow cytometry. PRR11 is highly expressed in a variety of malignant tumors, including osteosarcoma tissue and cells, and has a significant impact on prognosis. Univariate Cox regression analysis revealed that PRR11 was an independent prognostic factor for osteosarcoma. The gene set enrichment analysis results showed that the differential genes were mainly enriched in the biological process of the cell cycle; the protein-protein interaction network mainly interacted with the regulatory genes of the cell cycle. PRR11 promotes the invasion, migration, and proliferation of osteosarcoma cells and inhibits their apoptosis. Comprehensive bioinformatics analysis revealed that PRR11 promotes the malignancy of osteosarcoma cells mainly by participating in cell cycle regulation, and has an important impact on osteosarcoma prognosis. PRR11 may provide the basis for prognosis and treatment in patients with osteosarcoma.
Subject(s)
Bone Neoplasms , Osteosarcoma , Humans , Apoptosis/genetics , Bone Neoplasms/genetics , Bone Neoplasms/pathology , Cell Line, Tumor , Cell Proliferation/genetics , Clinical Relevance , Gene Expression Regulation, Neoplastic , Osteosarcoma/genetics , Osteosarcoma/pathology , Proteins/genetics , Proteins/metabolism , Up-RegulationABSTRACT
This paper reports the flow synthesis of highly reactive polyisobutylenes (HRPIBs) in pure n-hexane using properly prepared AlCl3·Et2O crystals in conjunction with AlCl3·iPr2O solution as coinitiators. By preparing AlCl3·iPr2O solution and AlCl3·Et2O crystals separately, the cationic polymerization of isobutylene proceeded smoothly under a wide range of monomer concentrations (0.33-1.30 M) in the presence of H2O as an initiator, affording a high yield (â¼89%) and a moderate exo-olefin terminal group content (60-75%) in 10 min. The various functions of iPr2O and Et2O in the initiator solution were comprehensively revealed from the polymerization results, attenuated total reflection-Fourier transform infrared and 27Al nuclear magnetic resonance spectra, and density functional theory simulations. AlCl3·iPr2O was confirmed to be the key component that stabilized carbenium ions. The AlCl3·Et2O complex was the key component to promote proton elimination. Free Et2O should be removed to inhibit its negative effect on isomerization. This new strategy may lead to high commercial interest in HRPIB synthesis in pure green solvent and could potentially be extended to other initiation systems containing solid Lewis acids.
ABSTRACT
In this article, nanostructured amorphous FePO4 (a-FePO4)-carbon nanotube (CNT) composites, with high purity of FePO4 and a controllable FePO4/C ratio, were directly synthesized by a fast nanoprecipitation process in a microreactor, using Fe(NO3)3 and (NH4)3PO4 as precursors. Oxidized CNTs are well dispersed via strong electrostatic repulsion in a high pH solution system. Subsequently, a-FePO4 nanoparticles are adhered onto CNTs just following the fast nanoprecipitation process; then, the precipitated composites are compacted by ball-milling, forming a compact conductive network with well dispersed and highly loaded active materials. As cathode materials for lithium-ion batteries, the composites exhibit a capacity of 175.8 mAh g-1 at 0.1 C, close to the theoretical capacity (178 mAh g-1), and a good cycle performance with a reversible capacity of 137.0 mAh g-1 after 500 cycles at 5 C. Importantly, the enhanced micromixing enables fast nanoprecipitation in suspension and opens a shortcut for constructing nanostructured composites that have potential in functionalization and are easy to handle.
ABSTRACT
A facile strategy to construct composites of amorphous FePO4 (a-FePO4) nanoparticles and carbon additives with high dispersion and tap density was developed in this work, in which the a-FePO4·2H2O nanoparticles were handled without drying until being mixed with carbon nanomaterials in water to assure high dispersion of a-FePO4·2H2O nanoparticles and carbon nanomaterials; the controlled sedimentation was exploited by rapid adjustment of the pH value via a micromixer to obtain the composites that are easy to manipulate; the composites were endowed with high tap density after simple ball-milling. Using this strategy, hybrid carbon additives were uniformly introduced into the a-FePO4 cathode to form a hierarchical 3D conductive network. Through proper distribution of these components to provide both long- and short-range electron pathways, the reversible discharge capacity could reach 175.6 mA h g-1 at 0.1 C and 139.1 mA h g-1 at 5 C. The composites of a-FePO4, carbon black, and carbon nanotubes (CNT) exhibited the distinct advantages of low cost and excellent rate capacity over the composites of a-FePO4 and CNT, indicating the importance of optimizing the hierarchical structure of cathode composites. The high effectiveness of this construction strategy to build a hierarchical conductive network is also promisingly used for the development of other functional nanocomposites.
ABSTRACT
In this work, we prepared different initiator solutions containing ether and AlCl3 by changing the addition sequence of ingredients, studied the interactions between ether and AlCl3 from the evolution of the Fourier transform infrared (FTIR) spectra by comparison, and investigated the catalytic performances of AlCl3 affected by ether for isobutylene polymerization. We observed that different preparation methods of initiator solutions could lead to two kinds of interactions between ether and H2O/AlCl3 in hexane. The strong interaction could stabilize carbenium ions and seriously decrease the catalytic performance, whereas the weak interaction could promote isomerization and proton elimination. Moreover, we found that the preparation method of initiator solutions was not a critical factor in CH2Cl2. Finally, a universal mechanism based on the AlCl3-involved interactions in different solvents was proposed to understand the effects of ether on the cationic polymerization catalyzed by AlCl3 thoroughly.
ABSTRACT
Ethyl diazoacetate (EDA) commonly experiences intensive decomposition as well as complex conversion concerning safety and efficiency. In this work, a careful kinetics study on the thermal decomposition of EDA was isothermally conducted in a microtube reactor to establish a mechanism-based kinetic model. The model parameters were well calibrated with experimental data including the yield of dimmers and the conversion of EDA, confirming the rationality of the proposed three-step reaction route. It allows the model to concisely describe the complex species transformations during EDA decomposition, which is unavailable for an apparent kinetic model. Considering an isothermal reaction system and the tolerance of EDA consumption by thermal decomposition, this work could help reveal the requirement on the kinetic characteristics of the desired catalytic reaction in which EDA is involved, as a reference on reaction process modeling and regulation.
ABSTRACT
To develop a green, cost-efficient and robust peroxidase mimic, micro/nano hierarchical morphology (for ease of separation and reuse), relative chemically stable composition (for ease of storage) and stable crystal structure (for long-term stability) are highly desired. Herein, using phosphoric acid as a chelating ligand to control the release of iron ions, hierarchical iron(III) hydrogen phosphate hydrate crystals are successfully prepared by nanosheets formation and following self-assembling in a facile low-temperature hydrothermal process. They are first found to have peroxidase-like activity and showed higher affinity for H2O2 and lower affinity for 3,3',5,5'-tetramethylbenzidine compared with horseradish peroxidase. The affinity feature is used for quantitative detection of H2O2 and shows a wide linear detection range from 57.4 to 525.8 µM (R(2) = 0.994) with a low detection limit of 1 µM. Benefited from chemical stability of hierarchical iron(III) salt crystals, they own good reproducibility (relative standard deviation = 1.95% for 10 independent measurements), long-term stability (no activity loss after 10 cycles), and ease of recovery (by simple centrifugation). Because the method is easily accessible, iron hydrogen phosphate hierarchical crystals have great potential for practical use of H2O2 sensing and detection under harsh conditions.
Subject(s)
Biosensing Techniques/methods , Ferric Compounds/chemistry , Hydrogen Peroxide/analysis , Peroxidase/chemistry , Peroxidase/metabolism , Hydrogen Peroxide/metabolismABSTRACT
In this study, we developed a new method for the direct measurement of differential pressures in a co-flow junction microfluidic device using a Capillary Laplace Gauge (CLG). The CLG - used inside the microchannel device--was designed using a tapered glass-capillary set up in co-flow junction architecture with a three-phase liquid-liquid-gas system with two flowing liquid phases and an entrained gas phase. By taking advantage of the Laplace equation, basic geometric relations and an integrated image analysis program, the movement of the entrained gas phase with the flow of the liquid-phases is tracked and monitored, allowing the gauge to function as an ultra-sensitive, integrated, differential pressure sensor measuring fluctuations in the liquid-dispersed phase channel pressure as small as tens of Pascals caused by droplet formation. The gauge was used to monitor the drop formation and breakup process in a co-flow junction microfluidic device under different flow conditions across a large range (1 × 10(-3) to 2.0 × 10(-1)) of capillary numbers. In addition to being able to monitor short and long term dispersed phase pressure fluctuation trends for both single drop and large droplet populations, the gauge was also used to clearly identify a transition between the dripping and jetting flow regimes. Overall, the combination of a unique, integrated image analysis program with this new type of sensor serves as a powerful tool with great potential for a variety of different research and industrial applications requiring sensitive microchannel pressure measurements.
ABSTRACT
This work introduces a microfluidic method for the generation of monodispersed microdroplets by using temperature controlled bubble condensation processes. In this method, the dispersed phase is first vaporized in the feeding pipe and ruptured to monodispersed bubbles in a coflowing stream. These bubbles are then condensed in the downstream pipe, where monodispersed microdroplets are obtained. This method ensures the narrow distribution of droplet diameters and prepares microdroplets less than 200 µm in sub-millimeter fluidic devices.
ABSTRACT
Heavy solvents absorption appears to be very attractive in recovering of volatile organic compounds (VOCs) from industrial tail gas. Their high viscosities make good dispersion required but difficult to reduce mass transfer resistance. Microencapsulation techniques provide a candidate solution. In this paper, vapor pressures for toluene+poly(dimethylsiloxane) (PDMS) mixtures were measured at temperature ranging from 273.2K to 343.2K. Polyacrylonitrile (PAN) hollow microspheres, prepared by orifice dispersion plus solvent extraction method, was used to immobilize PDMS. The capacity was adjusted from 2.3g to 9.3g PDMS/g PAN by addition of cyclohexane in PDMS during solvent impregnation. The breakthrough curves of column packed with PDMS/PAN microcapsules were determined, indicating shapes close to ideality, high absorption efficiencies and considerable absorption capacities before breakthrough. The influence of operational temperature, concentration of feed and gas feed flow rate on the absorption process were investigated as well. A mathematical model, suitable for dilute gas absorption process, was used to simulate the breakthrough curves. This model has proved to be useful to fit curves and analyze the absorption kinetics of PDMS/PAN microcapsules column. After absorption, the column can be regenerated completely by gas stripping. Enrichment of toluene was founded by increasing desorption temperature. Through absorption and desorption by turns, the stability of PDMS/PAN microcapsules column was verified.
Subject(s)
Toluene/isolation & purification , Absorption , Capsules , Gases , Indicators and Reagents , Kinetics , Microscopy, Electron, Scanning , Particle Size , Thermodynamics , Toluene/chemistry , Viscosity , Waste Disposal, FluidABSTRACT
This article describes a simple method for the fabrication of microscale polymer tubes. A double co-axial microchannel device was designed and fabricated. Liquid/liquid/liquid multiphase co-laminar flows were realized in a microchannel by choosing working systems. Three kinds of polymeric solutions were selected as the middle phase while a polyethyleneglycol aqueous solution was used as the inner and outer phases in the microfluidic process. The outer and inner phases acted as extractants of the polymer solvent. A stable double core-annular flow was formed by optimizing the composition of the outer and inner phases, and highly uniform tubes were successfully fabricated by the solvent extraction method. Both the outer diameter of the tubes and the wall thickness could be adjusted from 300 microm to 900 microm and from 40 microm to 150 microm by varying the flux of the fluids and the rolling velocity of the collection roller. In addition, titanium dioxide (TiO2) nanoparticles were successfully encapsulated into the polymer tubes with this technique. This technology has the potential to generate hollow fiber membranes for applications in separation and reaction processes.
ABSTRACT
Polysulphone (PSF) microcapsules containing 1-octanol were prepared with solvent extraction method for the recovery of caprolactam. One-step and two-step processes were, respectively, applied to prepare microcapsules. In order to get high extractant loading, a loading method with the assistance of ultrasound has been developed. With the two-step preparation process the extractant loss can be avoided. A very high extractant loading ratio of 5.96 g g(-1) and the maximum uptake to caprolactam of 65.6 mg g(-1) were achieved. Under the action of ultrasound the extractant loading efficiency is greatly intensified. With the one-step process 1-octanol loading ratio is highly limited. Only 1.74 g g(-1) loading ratio and 29.9 mg g(-1) uptake to caprolactam were realized. Meanwhile the extractant loss in the one-step process is serious. Considering extraction capacity and extractant loss in the preparation process, it is suggested that PSF microcapsules containing 1-octanol should be prepared with the two-step process. To fasten mass transfer rate, microcapsules with relatively smaller size are desired.
Subject(s)
1-Octanol/chemistry , Caprolactam/chemistry , Capsules/chemistry , Polymers/chemistry , Sulfones/chemistry , Caprolactam/isolation & purification , Chemistry/methods , Chromatography/methods , Drug Compounding/methods , Equipment Design , Kinetics , Microscopy, Electron, Scanning , Oxygen/chemistry , Solvents/chemistryABSTRACT
Removal of volatile organic contaminants (VOCs) from water is an important task for environmental protection. Silicone oil has many merits but can not be directly applied in extraction of VOCs due to its high viscosity, which can negatively affect the mass transfer. Therefore a new purification method with extractant microcapsules has been developed in this work. Polysulphone microcapsules containing silicone oil were prepared successfully using a solvent evaporation method. The mass transfer performance was determined with toluene as the recovered component and with the prepared microcapsules as the separation agent. Extraction equilibrium could be reached in approximately 60 min. The maximum uptake of toluene was 24.5 mg g(-1) microcapsules. Microcapsules were reused four times and showed very good stability. Using microcapsules containing silicone oil as the separation agent, high and stable extraction capacity has been successfully achieved, especially without any phase dispersion and phase separation processes. It may be concluded that low energy will be required in the new separation process.
Subject(s)
Capsules , Polymers/administration & dosage , Silicone Oils/chemistry , Sulfones/administration & dosage , Water Purification/methods , Water/chemistry , Chemistry, Organic/methods , Equipment Design , Models, Chemical , Models, Statistical , Polymers/chemistry , Solvents/chemistry , Spectrophotometry, Infrared , Sulfones/chemistry , Surface Properties , Toluene/chemistry , Water Pollutants, Chemical , Water Purification/instrumentationABSTRACT
This paper presents an improved solvent evaporation method with silicone oil (PDMS) as the continuous phase for preparation of microcapsules to make more polymer solvents available. A microchannel device was used to produce emulsions instead of mechanical stirring to prepare the mono-dispersed microcapsules. Under the conditions of lower evaporation temperature and shorter evaporation time, uniform polyacrylonitrile (PAN) microcapsules containing Aliquat 336 (ALQ) have been successfully prepared. N,N-dimethylformamide (DMF) with lower evaporation ability was applied as the polymer solvent. The prepared microcapsules have rough surfaces and homogeneously internal structures. By changing the two-phase flow rate, the mean size of microcapsules can be easily controlled. When more ALQ was added in polymer solution, the loading ratio of microcapsules increased. The mass transfer performance and stability were determined by extraction of Cr (VI) ions from its aqueous solution. The mass transfer rate was fast enough. After three times of repeated extraction and stripping, the microcapsules kept almost the same extraction ability, which indicated that the microcapsules have very good stability.