The rapid development of the information era has led to in-creased power consumption,which generates more heat.This requires more efficient thermal management systems,with the most direct ap-proach being the developme...The rapid development of the information era has led to in-creased power consumption,which generates more heat.This requires more efficient thermal management systems,with the most direct ap-proach being the development of su-perior thermal interface materials(TIMs).Mesocarbon microbeads(MCMBs)have several desirable properties for this purpose,includ-ing high thermal conductivity and excellent thermal stability.Although their thermal conductivity(K)may not be exceptional among all carbon materials,their ease of production and low cost make them ideal filler materials for developing a new generation of carbon-based TIMs.We report the fabrication of high-performance TIMs by incorporating MCMBs in a polyimide(PI)framework,producing highly graphitized PI/MCMB(PM)foams and anisotropic polydimethylsiloxane/PM(PDMS/PM)composites with a high thermal conductivity using directional freezing and high-temperature thermal annealing.The resulting materials had a high through-plane(TP)K of 15.926 W·m^(−1)·K^(−1),4.83 times that of conventional thermally conductive silicone pads and 88.5 times higher than that of pure PDMS.The composites had excellent mechanical properties and thermal stability,meeting the de-mands of modern electronic products for integration,multi-functionality,and miniaturization.展开更多
A transformation of naphthalene-based coalescenced mesophase pitch(NMP)to mesophase microbeads was achieved by heating a mixture of NMP and fullerene(C_(60)).This is different from the conventional process of the liqu...A transformation of naphthalene-based coalescenced mesophase pitch(NMP)to mesophase microbeads was achieved by heating a mixture of NMP and fullerene(C_(60)).This is different from the conventional process of the liquid-phase carbonization of isotropic pitch to the emergence of carbon microbeads in the matrix and finally their growth to form a 100%anisotropic bulk meso-phase,but rather a reverse transformation.The effects of C_(60) loading and reaction temperature on the morphological transformation of mesophase were investigated by polarizing optical and scanning electron microscopies.The physical changes in the NMP induced by C_(60) were characterized by thermogravimetric analysis,Fourier transform infrared spectroscopy,X-ray diffractometry and Raman spectroscopy.The results show that the coalesced NMP can be converted to a spherical type at 300-320℃ with the addition of 5%C_(60),and the size of the mesophase microbeads increases with increasing temperature.Furthermore,a model is established to ex-plain the unique induction effect of C_(60) in the transformation process.This work makes the morphological transformation of MP con-trollable,and provides a new idea for the understanding and research of mesophase pitch.展开更多
Novel oral microbeads were developed based on a biopolymer–drug conjugate of doxorubicin(DOX) conjugated with thiolated pectin via reducible disulfide bonds. The microbeads were fabricated by ionotropic gelation with...Novel oral microbeads were developed based on a biopolymer–drug conjugate of doxorubicin(DOX) conjugated with thiolated pectin via reducible disulfide bonds. The microbeads were fabricated by ionotropic gelation with cations such as Al3+, Ca2+ and Zn2+. The results showed that using zinc acetate can produce the strongest microbeads with spherical shape.However, the microbeads prepared from thiolated pectin–DOX conjugate were very soft and irregular in shape. To produce more spherical microbeads with suitable strength, the native pectin was then added to the formulations. The particle size of the microbeads ranged from 0.87 to 1.14 mm. The morphology of the microbeads was characterized by optical and scanning electron microscopy. DOX was still in crystalline form when used in preparing the microbeads, as confirmed by powder X-ray diffractometry. Drug release profiles showed that the microbeads containing thiolated pectin–DOX conjugate exhibited reduction-responsive character;in reducing environments, the thiolated pectin–DOX conjugate could uncouple resulting from a cleavage of the disulfide linkers and consequently release the DOX. The best-fit release kinetics of the microbeads containing thiolated pectin–DOX conjugate, in the medium without reducing agent, fit the Korsmeyer–Peppas model while those in the medium with reducing agent fit a zero-order release model. These results suggested that the microbeads containing thiolated pectin–DOX conjugate may be a promising platform for cancer-targeted delivery of DOX, exploiting the reducing environment typically found in tumors.展开更多
Fluorescently encoded microbeads are in demand for multiplexed applications in different fields.Compared to organic dye-based commercially available Luminex's x MAP technology, upconversion nanoparticles(UCNPs) ar...Fluorescently encoded microbeads are in demand for multiplexed applications in different fields.Compared to organic dye-based commercially available Luminex's x MAP technology, upconversion nanoparticles(UCNPs) are better alternatives due to their large antiStokes shift, photostability, nil background, and single wavelength excitation. Here, we developed a new multiplexed detection system using UCNPs for encoding poly(ethylene glycol) diacrylate(PEGDA) microbeads as well as for labeling reporter antibody. However, to prepare UCNPs-encoded microbeads, currently used swellingbased encapsulation leads to non-uniformity, which is undesirable for fluorescence-based multiplexing. Hence,we utilized droplet microfluidics to obtain encoded microbeads of uniform size, shape, and UCNPs distribution inside. Additionally, PEGDA microbeads lack functionality for probe antibodies conjugation on their surface.Methods to functionalize the surface of PEGDA microbeads(acrylic acid incorporation, polydopamine coating)reported thus far quench the fluorescence of UCNPs. Here,PEGDA microbeads surface was coated with silica followed by carboxyl modification without compromising the fluorescence intensity of UCNPs. In this study, droplet microfluidics-assisted UCNPs-encoded microbeads of uniform shape, size, and fluorescence were prepared.Multiple color codes were generated by mixing UCNPs emitting red and green colors at different ratios prior to encapsulation. UCNPs emitting blue color were used to label the reporter antibody. Probe antibodies were covalently immobilized on red UCNPs-encoded microbeads for specific capture of human serum albumin(HSA) as a model protein. The system was also demonstrated for multiplexed detection of both human C-reactive protein(hCRP) and HSA protein by immobilizing anti-h CRP antibodies on green UCNPs.展开更多
Bimetallic Ni–Co sulfides are outstanding pseudocapacitive materials with high electrochemical activity and excellent energy storage performance as electrodes for high-performance supercapacitors.In this study,a nove...Bimetallic Ni–Co sulfides are outstanding pseudocapacitive materials with high electrochemical activity and excellent energy storage performance as electrodes for high-performance supercapacitors.In this study,a novel urchin-like NiCo2S4@mesocarbon microbead(NCS@MCMB) composite with a core–shell structure was prepared by a facile two-step hydrothermal method.The highly conductive MCMBs offered abundant adsorption sites for the growth of NCS nanoneedles,which allowed each nanoneedle to fully unfold without aggregation,resulting in improved NCS utilization and efficient electron/ion transferin the electrolyte.When applied as an electrode material for supercapacitors,the composite exhibited a maximum specific capacitance of 936 Fg-1 at 1 Ag-1 and a capacitance retention of 94% after 3000 cycles at 5 Ag-1,because of the synergistic effect of MCMB and NCS.Moreover,we fabricated an asymmetric supercapacitor based on the NCS@MCMB composite,which exhibited enlarged voltage windows and could power a light-emitting diode device for several minutes,further demonstrating the exceptional electrochemical performance of the NCS@MCMB composite.展开更多
DCLR-P was prepared by direct coal liquefaction residue (DCLR) with ash removal.In the present experiments,mesocarbon microbeads (MCMBs) were prepared by co-carbonization of coal tar pitch (CTP) and DCLR-P.With the in...DCLR-P was prepared by direct coal liquefaction residue (DCLR) with ash removal.In the present experiments,mesocarbon microbeads (MCMBs) were prepared by co-carbonization of coal tar pitch (CTP) and DCLR-P.With the increase of DCLR-P content,the yield of MCMBs increased from 47.8% to 56.8%.At the same time,the particle sizes distribution of MCMBs was narrowed,resulting in the decrease of D9o/D10 ratio from 154.88 to 6.53.The results showed that DCLR-P had a positive effect on the preparation of MCMBs.1H-NMR,FTIR,SEM and XRD were used to analyze the mechanisms and characteristics of MCMBs prepared by co-carbonization of CTP and DCLR-P.The results showed that the Proton Donor Quality Index (PDQI) of DCLR-P was 13.32,significantly higher than that of CTP (0.83).This indicated that DCLR-P had more naphthenic structure than CTP,which leads to hydrogen transferring in polycondensation reaction.The aliphatic structure of DCLR-P can improve the solubility and fusibility of mesophase,thereby making the structure of MCMBs more structured.The microstructure of the graphitized MCMBs had a substantially parallel carbon layer useful for its electrical performance.The performance of graphitized MCMBs as a negative electrode material for Li-ion batteries was tested.The particle sizes,tap density,specific surface area and initial charge-discharge efficiency of graphitized MCMBs met the requirements of CMB-I in GB/T-24533-2009.However,the initial discharge capacity of graphitized MCMB was only 296.3 mA h g-1 due to the low degree of graphitization of MCMBs.展开更多
The practical application of silica-based composites as an alternative to commercial graphite anode materials is hampered by their large volumetric expansion,poor conductivity,and low Coulombic efficiency.In this work...The practical application of silica-based composites as an alternative to commercial graphite anode materials is hampered by their large volumetric expansion,poor conductivity,and low Coulombic efficiency.In this work,a novel silica/oxidized mesocarbon microbead/amorphous carbon(SiO2/O’MCMB/C)hierarchical structure in which SiO2 is sandwiched between spherical graphite and amorphous carbon shell was succes sfully fabricated through hydrogen bonding-assisted self-assembly and post-carbon coating method.The obtained three-layer hierarchical structure effectively accommodates the volumetric expansion of SiO2 and significantly enhances the electronic conductivity of composite materials.Moreover,the outer layer of amorphous carbon effectively increases the diffusion rate of lithium ions and promotes the formation of stable SEI film.As a result,the SiO2/O’MCMB/C composite exhibits superior electrochemical performance with a reversible capacity of 459.5 mA h/g in the first cycle,and the corresponding Coulombic efficiency is 62.8%.After 300 cycles,the capacity climbs to around 600 mA h/g.This synthetic route provides an efficient method for preparing SiO2 supported on graphite with excellent electrochemical performance,which is likely to promote its commercial applications.展开更多
AIM： To characterize whether a glaucoma model with chronic elevation of the intraocular pressure （IOP） was able to be induced by anterior chamber injection of microbeads in rabbits.METHODS： In order to screen the ...AIM： To characterize whether a glaucoma model with chronic elevation of the intraocular pressure （IOP） was able to be induced by anterior chamber injection of microbeads in rabbits.METHODS： In order to screen the optimal dose of microbead injection, IOP was measured every 3d for 4wk using handheld applanation tonometer after a single intracameral injection of 10 μL, 25 μL, 50 μL or 100 μL microbeads （5×10^6 beads/mL; n=6/group） in New Zealand White rabbits. To prolong IOP elevation, two intracameral injections of 50 μL microbeads or phosphate buffer saline （PBS） were made respectively at days 0 and 21 （n=24/group）. The fellow eye was not treated. At 5wk after the second injection of microbeads or PBS, bright-field microscopy and transmission electron microscopy （TEM） were used to assess the changes in the retina. The expression of glial fibrillary acidic protein （GFAP） in the retina was evaluated by immunofluorescence, quantitative real-time polymerase chain reaction and Western blot at 5wk after the second injection of microbeads.RESULTS： Following a single intracameral injection of 10 μL, 25 μL, 50 μL or 100 μL microbead, IOP levels showed a gradual increase and a later decrease over a 4wk period after a single injection of microbead into the anterior chamber of rabbits. A peak IOP was observed at day 15 after injection. No significant difference in peak value of IOP was found between 10 μL and 25 μL groups （17.13±1.25 mm Hg vs 17.63±0.74 mm Hg; P=0.346）. The peak value of IOP from 50 μL group （23.25±1.16 mm Hg） was significantly higher than 10 μL and 25 μL groups （all P〈0.05）. Administration of 100 μL microbead solution （23.00±0.93 mm Hg） did not lead to a significant increase in IOP compared to the 50 μL group （P=0.64）. A prolonged elevated IOP duration up to 8wk was achieved by administering two injections of 50 μL microbeads （20.48±1.21 mm Hg vs 13.60±0.90 mm Hg in PBS-injected group; P〈0.05）. The bright-field and TEM were used to assess the changes of retinal ganglion cells （RGCs）. Compared with PBS-injected group, the extended IOP elevation was associated with the degeneration of optic nerve, the reduction of RGC axons （47.16%, P〈0.05） and the increased GFAP expression in the retina （4.74±1.10 vs 1.00±0.46, P〈0.05）.CONCLUSION： Two injections of microbeads into the ocular anterior chamber of rabbits lead to a prolonged IOP elevation which results in structural abnormality as well as loss in RGCs and their axons without observable ocular structural damage or inflammatory response. We have therefore established a novel and practical model of experimental glaucoma in rabbits.展开更多
In this paper, Fe-doped TiO_2 photocatalyst supported on hollow glass microbeads(Fe-TiO_2 /beads)is prepared by dip-coating method, which uses hollow glass microbeads as the carriers and tetrabutylorthotitanate [Ti(O...In this paper, Fe-doped TiO_2 photocatalyst supported on hollow glass microbeads(Fe-TiO_2 /beads)is prepared by dip-coating method, which uses hollow glass microbeads as the carriers and tetrabutylorthotitanate [Ti(OC_4H_9)_4] as the raw material. The phase structure, ingredient, morphologies, particle size and shell thickness of the products are characterized by X-ray powder diffraction(XRD), energy-dispersive spectroscopy(EDS) and field emission scanning electron microscope(FESEM). The feasibility of photocatylic degradation of Rhodamine B(Rh B) under illumination of UV-vis light is studied. The results show that the core-shell structure catalyst is composed of Fe-doped anatase TiO_2 and hollow glass microbeads, and the catalytic activity of the TiO_2 is markedly enhanced by Fe ion doping. The optimum concentration of Fe ion is 0.1%(molecular fraction) in the precursor and the photocatalytic activity can be increased to 98% compared with that of the undoped one. The presence of ferrum elements neither influences the transformation of anatase to rutile, nor creates new crystal phases. The possible mechanism of photocatalytic oxidation is also discussed.展开更多
The utilization of Calcium Phosphate Cement(CPC)is limited due to its low mechanical strength and difficulty to seed cells deep into the scaffold.The objectives of this study were to:(1)develop a 3D-printed CPC-dopami...The utilization of Calcium Phosphate Cement(CPC)is limited due to its low mechanical strength and difficulty to seed cells deep into the scaffold.The objectives of this study were to:(1)develop a 3D-printed CPC-dopamine-metformin scaffold encapsulating human periodontal ligament stem cells(hPDLSCs),(2)investigate the effect of dopamine on the performance of CPC,and(3)evaluate the effect of microbead degradation and metformin release on the osteogenic differentiation of the released hPDLSCs.The mechanical property of the CPC scaffolds was elevated by adding dopamine,and the CPC scaffold with 7 wt.%dopamine had the highest compressive strength(7.35 MPa).Four types of microbeads with different content of alginate(oxidized alginate),hPDLSCs,and 2%metformin were fabricated.Morphological and cell counting kit tests confirm that the hPDLSCs are protected by microbeads encapsulation during the CPC setting process.The alkaline phosphatase test indicates that the osteogenic differentiation of hPDLSCs was enhanced by the fast release of cells and metformin.The microbeads consisting of 2%oxidized alginate and 2%metformin were optimal for cell delivery due to favorable cell release and osteogenic differentiation.This CPC scaffold is promising used for bone regeneration in dental,craniofacial,and orthopedic applications.展开更多
Dual-ion batteries(DIBs)have attracted tremendous attention owing to their high operating voltage and are considered promising candidates for low-cost clean energy storage devices.However,the decomposition of electrol...Dual-ion batteries(DIBs)have attracted tremendous attention owing to their high operating voltage and are considered promising candidates for low-cost clean energy storage devices.However,the decomposition of electrolytes and collapse of the cathode structure may lead to low Coulombic efficiency(CE)and low cycling stability of DIBs.Wide-layered electrode materials can accommodate the intercalation/deintercalation of large anions,which is believed to overcome these issues.Herein,expanded mesocarbon microbeads(200HRO-MCMB)possessing an enlarged interlayer spacing(0.405 nm)were prepared via modified Hummers and subcritical hydrothermal reduction methods.After the indispensable electrochemical activation,200HRO-MCMB(hydrothermal reduction at 200℃)exhibited a high specific capacity(120 mAh·g^(-1)at50 mA·g^(-1))when used as a cathode for a sodium-based DIB,and the CE significantly improved within the 2.0-4.5 V voltage range.Additionally,the cycling stability exceeded over 600 cycles.Remarkably,this cathode possessed enlarged interlayers that decreased the barrier of PF6^(-)transport,and the battery storage mechanism corresponded to a transitioning state between double-layer capacitance and Faradaic intercalation.Undoubtedly,this work will expand the scope of the practical application of low-cost sodium-based DIBs.展开更多
Rigid PSDVB microbeads have been modified with poly(vinyl alcohol) (PVA) adsorbed on their surface to produce an affinity medium. Then Cibacron Blue F3GA was covalently attached to the supports. The initial concentrat...Rigid PSDVB microbeads have been modified with poly(vinyl alcohol) (PVA) adsorbed on their surface to produce an affinity medium. Then Cibacron Blue F3GA was covalently attached to the supports. The initial concentration of PVA has effect on the adsorption of PVA. The non-specific interaction of bovine serum albumin (BSA) on the microbeads decreases with the PVA adsorbed. The pH stability test shows that the affinity medium is stable up to pH 11.0. And it has specific interaction with lysozyme, but not with pepsin.展开更多
AIM： To investigate the effect of microbead iridocorneal angle occlusion on intraocular pressure（IOP） diurnal fluctuation in rat eyes. METHODS： Male Dark Agouti（DA） rats, 8-10 week old, were each given a single ...AIM： To investigate the effect of microbead iridocorneal angle occlusion on intraocular pressure（IOP） diurnal fluctuation in rat eyes. METHODS： Male Dark Agouti（DA） rats, 8-10 week old, were each given a single intracameral injection of microbeads, followed by injection of dispersive viscoelastic solution. The right eye served as the experimental eye, while the left eye served as the control. IOP was measured twice daily postoperatively for 3 wk and compared between groups. At the end of 3 wk, the rats were sacrificed and the eyes were harvested for histological analysis and retinal ganglion cell（RGC） counting. RESULTS： After microbead injection, experimental eyes had significantly higher dark time IOP than controls from the second week to the third week [2 nd week： 22.92±1.631 mm Hg（n=5） vs 17.35±0.751 mm Hg（n=5）; 3 rd week： 23.59±1.494 mm Hg vs 17.73±0.592 mm Hg（n=5）], while light time IOP was comparable between groups. The fluctuation levels of IOP in the experimental eyes were 7.21±0.398 mm Hg（n=5）, 9.50±1.017 mm Hg（n=5） and 10.66±0.894 mm Hg（n=5） from the first week to the third week after injection. Comparatively, they were significantly lower in the control eyes, which were 4.69±0.323 mm Hg（n=5）, 2.84±1.122 mm Hg（n=5） and 4.98±0.603 mm Hg（n=5） respectively. However, at the end of 3 wk, the larger fluctuations in IOP in the experimental eyes was not associated with a significant loss of RGCs. CONCLUSION： Microbead occlusion exacerbates diurnal IOP fluctuation in rats. This reported model may serve as a method of investigating the pathological effects of IOP fluctuation. A longer observation period, or repeated injections, may be needed to observe a significant change in RGC density.展开更多
Optical magnetic twisting cytometry and traction force microscopy are two advanced cell mechanics research tools that employ optical methods to track the motion of microbeads that are either bound to the surface or em...Optical magnetic twisting cytometry and traction force microscopy are two advanced cell mechanics research tools that employ optical methods to track the motion of microbeads that are either bound to the surface or embedded in the substrate underneath the cell.The former measures rheological properties of the cell such as cell stiffness,and the latter measures cell traction force dynamics.Here we describe the principles of these two cell mechanics research tools and an example of using them to study physical behaviors of the living cell in response to transient stretch or compression.We demonstrate that,when subjected to a stretchunstretch manipulation,both the stiffness and traction force of adherent cells promptly reduced,and then gradually recover up to the level prior to the stretch.Immunofluorescent staining and Western blotting results indicate that the actin cytoskeleton of the cells underwent a corresponding disruption and reassembly process almost in step with the changes of cell mechanics.Interestingly,when subjected to compression,the cells did not show such particular behaviors.Taken together,we conclude that adherent cells are very sensitive to the transient stretch but not transient compression,and the stretch-induced cell response is due to the dynamics of actin polymerization.展开更多
The graphene/mesocarbon microbead(MCMB)composite is assessed as an anode material with a high capacity for lithium-ion batteries.The composite electrode exhibits improved cycling stability and rate capability,deliveri...The graphene/mesocarbon microbead(MCMB)composite is assessed as an anode material with a high capacity for lithium-ion batteries.The composite electrode exhibits improved cycling stability and rate capability,delivering a high initial charge/discharge capacity of 421.4 mA·h/g/494.8 mA·h/g as well as an excellent capacity retention over 500 cycles at a current density of 40 mA/g.At a higher current density of 800 mA/g,the electrode still retains 35%of its initial capacity which exceeds the capacity retention of pure graphene or MCMB reference electrodes.Cyclic voltammetry and electrochemical impedance spectroscopy reveal that the composite electrode favors electrochemical kinetics as compared with graphene and MCMB separately.Superior electrochemical properties suggest a strong synergetic effect between highly conductive graphene and MCMB.展开更多
Well-defined raspberry-like magnetic microbeads （RMMBs） as immunoassay solid carriers were pre- pared by chemicM covalent binding between Fe304 magnetic microspheres and SiO2 nanoparticles. These RMMBs were not as a...Well-defined raspberry-like magnetic microbeads （RMMBs） as immunoassay solid carriers were pre- pared by chemicM covalent binding between Fe304 magnetic microspheres and SiO2 nanoparticles. These RMMBs were not as agglomerative as nano-sized magnetie particles （〈 200 nm）, which was an advangtage for high efficient magnetic separation. When compared to Fe304@SiO2 core-shell magnetic microbeads （CMMBs） with smooth surface, RMMBs exhibited stronger capacity to bind biomolecules. Limit of blank （LOB） and limit of detection （LoD） of HBsAg detection using RMMBs as carriers via chemiluminiscence immunoassay （CLIA） were 0.472 and 1.022 μg/L, respectively, showing a notable improvement compared with CMMBs whose LoB and LoD were 1.017 and 1.988 μg/L, respectively. All these indicated a great potential of RMMBs in immunoassay application.展开更多
Polystyrene （PS） @SiO2 core-shell microbeads with large pore and large particle size were prepared via layer-by-layer（LBL）assembly technique for potential applications in nano-micro composites. Negative silica nan...Polystyrene （PS） @SiO2 core-shell microbeads with large pore and large particle size were prepared via layer-by-layer（LBL）assembly technique for potential applications in nano-micro composites. Negative silica nanoparticles synthesized via modified St6ber method and cationic poly （diallyldimethylammonium chloride） were alternately adsorbed on the surface of microbeads. Zeta potential, size, and morphology of the microbeads were monitored during LBL assembly process to ensure the successful deposition of silica nanoparticles. The porous shell was characterized using nitrogen adsorption and desorption analyses, and the surface area, volume and diame- ter of the pores were derived. It is found that the porous shell thickness and the pore size can be tuned by changing the coating times of silica nanoparticles. Finally, PS@SiO2 core-shell microbeads with 5 grn PS solid core and 350 nm mesoporous shell （mean BJH pore diameter is ~27 nm） were used to load CdSe/ZnS quantum dots （QDs）. The fluorescence microscopic image and the optical amplification of the QDs-embedded microbeads （QDBs） indicate that the as-prepared core-shell microbeads can provide adequate space for QDs and may be useful for further application of nano-micro composites.展开更多
The amount of microbeads ingested by Daphnia magna decreases on exposure to toxic materials; tins oenawor was used to develop a toxicity test. To determine the toxicity of seven metals, D. magna were collected and hom...The amount of microbeads ingested by Daphnia magna decreases on exposure to toxic materials; tins oenawor was used to develop a toxicity test. To determine the toxicity of seven metals, D. magna were collected and homogenized, and the fluorescence intensity of the microbeads ingested by D. magna was measured. The amount of ingestion was determined from fluorescence intensity. The fluorescence intensity was half of that of the controls which was measured as the 30 min-FI50, and these data correlated well with those from an acute immobilization method （24 h-EC50）. An advantage of the method using fluorescent beads is that an estimate of the 24 h-EC50 can be obtained.展开更多
In view of the importance of dispersion agent,the amount of the crosslinking monomer and the diluent in suspension polymerization for the production of particle size narrowly distributed low-density stryene divinylben...In view of the importance of dispersion agent,the amount of the crosslinking monomer and the diluent in suspension polymerization for the production of particle size narrowly distributed low-density stryene divinylbenzene copolymer microbeads(LDPS),their actions are preliminarily investigated in this paper.Experimental results indicate that when both the gelatine and polyvinyl alcohol(PVA)are used dispersion agents,the better effect is achieved,DVB is helpful to the formation of the lower density fine particles,the proportionof the DVB/St should be between 1:1-1.5:1.Compared with toluene,gasoline is the more effective diluent for the above target.展开更多
The concept of microbeads and the use of plastic microbeads(as a form of micro plastic) in cosmetics were introduced. The legislations related to prohibition of plastic microbeads in cosmetics in different countries w...The concept of microbeads and the use of plastic microbeads(as a form of micro plastic) in cosmetics were introduced. The legislations related to prohibition of plastic microbeads in cosmetics in different countries were reviewed. And the harzards and alternatives of plastic microbeads were described.展开更多
文摘The rapid development of the information era has led to in-creased power consumption,which generates more heat.This requires more efficient thermal management systems,with the most direct ap-proach being the development of su-perior thermal interface materials(TIMs).Mesocarbon microbeads(MCMBs)have several desirable properties for this purpose,includ-ing high thermal conductivity and excellent thermal stability.Although their thermal conductivity(K)may not be exceptional among all carbon materials,their ease of production and low cost make them ideal filler materials for developing a new generation of carbon-based TIMs.We report the fabrication of high-performance TIMs by incorporating MCMBs in a polyimide(PI)framework,producing highly graphitized PI/MCMB(PM)foams and anisotropic polydimethylsiloxane/PM(PDMS/PM)composites with a high thermal conductivity using directional freezing and high-temperature thermal annealing.The resulting materials had a high through-plane(TP)K of 15.926 W·m^(−1)·K^(−1),4.83 times that of conventional thermally conductive silicone pads and 88.5 times higher than that of pure PDMS.The composites had excellent mechanical properties and thermal stability,meeting the de-mands of modern electronic products for integration,multi-functionality,and miniaturization.
文摘A transformation of naphthalene-based coalescenced mesophase pitch(NMP)to mesophase microbeads was achieved by heating a mixture of NMP and fullerene(C_(60)).This is different from the conventional process of the liquid-phase carbonization of isotropic pitch to the emergence of carbon microbeads in the matrix and finally their growth to form a 100%anisotropic bulk meso-phase,but rather a reverse transformation.The effects of C_(60) loading and reaction temperature on the morphological transformation of mesophase were investigated by polarizing optical and scanning electron microscopies.The physical changes in the NMP induced by C_(60) were characterized by thermogravimetric analysis,Fourier transform infrared spectroscopy,X-ray diffractometry and Raman spectroscopy.The results show that the coalesced NMP can be converted to a spherical type at 300-320℃ with the addition of 5%C_(60),and the size of the mesophase microbeads increases with increasing temperature.Furthermore,a model is established to ex-plain the unique induction effect of C_(60) in the transformation process.This work makes the morphological transformation of MP con-trollable,and provides a new idea for the understanding and research of mesophase pitch.
文摘Novel oral microbeads were developed based on a biopolymer–drug conjugate of doxorubicin(DOX) conjugated with thiolated pectin via reducible disulfide bonds. The microbeads were fabricated by ionotropic gelation with cations such as Al3+, Ca2+ and Zn2+. The results showed that using zinc acetate can produce the strongest microbeads with spherical shape.However, the microbeads prepared from thiolated pectin–DOX conjugate were very soft and irregular in shape. To produce more spherical microbeads with suitable strength, the native pectin was then added to the formulations. The particle size of the microbeads ranged from 0.87 to 1.14 mm. The morphology of the microbeads was characterized by optical and scanning electron microscopy. DOX was still in crystalline form when used in preparing the microbeads, as confirmed by powder X-ray diffractometry. Drug release profiles showed that the microbeads containing thiolated pectin–DOX conjugate exhibited reduction-responsive character;in reducing environments, the thiolated pectin–DOX conjugate could uncouple resulting from a cleavage of the disulfide linkers and consequently release the DOX. The best-fit release kinetics of the microbeads containing thiolated pectin–DOX conjugate, in the medium without reducing agent, fit the Korsmeyer–Peppas model while those in the medium with reducing agent fit a zero-order release model. These results suggested that the microbeads containing thiolated pectin–DOX conjugate may be a promising platform for cancer-targeted delivery of DOX, exploiting the reducing environment typically found in tumors.
基金the funding support from the Singapore Ministry of Education Academic Research Fund (AcRF Tier 3 Grant MOE2016-T3-1-004, R-397-000274-112 AcRF Tier 1 Grant R-397-000-270-114)
文摘Fluorescently encoded microbeads are in demand for multiplexed applications in different fields.Compared to organic dye-based commercially available Luminex's x MAP technology, upconversion nanoparticles(UCNPs) are better alternatives due to their large antiStokes shift, photostability, nil background, and single wavelength excitation. Here, we developed a new multiplexed detection system using UCNPs for encoding poly(ethylene glycol) diacrylate(PEGDA) microbeads as well as for labeling reporter antibody. However, to prepare UCNPs-encoded microbeads, currently used swellingbased encapsulation leads to non-uniformity, which is undesirable for fluorescence-based multiplexing. Hence,we utilized droplet microfluidics to obtain encoded microbeads of uniform size, shape, and UCNPs distribution inside. Additionally, PEGDA microbeads lack functionality for probe antibodies conjugation on their surface.Methods to functionalize the surface of PEGDA microbeads(acrylic acid incorporation, polydopamine coating)reported thus far quench the fluorescence of UCNPs. Here,PEGDA microbeads surface was coated with silica followed by carboxyl modification without compromising the fluorescence intensity of UCNPs. In this study, droplet microfluidics-assisted UCNPs-encoded microbeads of uniform shape, size, and fluorescence were prepared.Multiple color codes were generated by mixing UCNPs emitting red and green colors at different ratios prior to encapsulation. UCNPs emitting blue color were used to label the reporter antibody. Probe antibodies were covalently immobilized on red UCNPs-encoded microbeads for specific capture of human serum albumin(HSA) as a model protein. The system was also demonstrated for multiplexed detection of both human C-reactive protein(hCRP) and HSA protein by immobilizing anti-h CRP antibodies on green UCNPs.
基金jointly supported by the National Natural Science Foundations of China(No.51572246)the Fundamental Research Funds for the Central Universities(Nos.2652017401 and 2652015425)
文摘Bimetallic Ni–Co sulfides are outstanding pseudocapacitive materials with high electrochemical activity and excellent energy storage performance as electrodes for high-performance supercapacitors.In this study,a novel urchin-like NiCo2S4@mesocarbon microbead(NCS@MCMB) composite with a core–shell structure was prepared by a facile two-step hydrothermal method.The highly conductive MCMBs offered abundant adsorption sites for the growth of NCS nanoneedles,which allowed each nanoneedle to fully unfold without aggregation,resulting in improved NCS utilization and efficient electron/ion transferin the electrolyte.When applied as an electrode material for supercapacitors,the composite exhibited a maximum specific capacitance of 936 Fg-1 at 1 Ag-1 and a capacitance retention of 94% after 3000 cycles at 5 Ag-1,because of the synergistic effect of MCMB and NCS.Moreover,we fabricated an asymmetric supercapacitor based on the NCS@MCMB composite,which exhibited enlarged voltage windows and could power a light-emitting diode device for several minutes,further demonstrating the exceptional electrochemical performance of the NCS@MCMB composite.
基金Supported by National Key Research and Development Program of China(2018YFB0604601)and the Technology Innovation Fund of China coal research institute(2016CX01).
文摘DCLR-P was prepared by direct coal liquefaction residue (DCLR) with ash removal.In the present experiments,mesocarbon microbeads (MCMBs) were prepared by co-carbonization of coal tar pitch (CTP) and DCLR-P.With the increase of DCLR-P content,the yield of MCMBs increased from 47.8% to 56.8%.At the same time,the particle sizes distribution of MCMBs was narrowed,resulting in the decrease of D9o/D10 ratio from 154.88 to 6.53.The results showed that DCLR-P had a positive effect on the preparation of MCMBs.1H-NMR,FTIR,SEM and XRD were used to analyze the mechanisms and characteristics of MCMBs prepared by co-carbonization of CTP and DCLR-P.The results showed that the Proton Donor Quality Index (PDQI) of DCLR-P was 13.32,significantly higher than that of CTP (0.83).This indicated that DCLR-P had more naphthenic structure than CTP,which leads to hydrogen transferring in polycondensation reaction.The aliphatic structure of DCLR-P can improve the solubility and fusibility of mesophase,thereby making the structure of MCMBs more structured.The microstructure of the graphitized MCMBs had a substantially parallel carbon layer useful for its electrical performance.The performance of graphitized MCMBs as a negative electrode material for Li-ion batteries was tested.The particle sizes,tap density,specific surface area and initial charge-discharge efficiency of graphitized MCMBs met the requirements of CMB-I in GB/T-24533-2009.However,the initial discharge capacity of graphitized MCMB was only 296.3 mA h g-1 due to the low degree of graphitization of MCMBs.
基金supported by the National Key Research and Development Program of China (No.2016YFB0100511)
文摘The practical application of silica-based composites as an alternative to commercial graphite anode materials is hampered by their large volumetric expansion,poor conductivity,and low Coulombic efficiency.In this work,a novel silica/oxidized mesocarbon microbead/amorphous carbon(SiO2/O’MCMB/C)hierarchical structure in which SiO2 is sandwiched between spherical graphite and amorphous carbon shell was succes sfully fabricated through hydrogen bonding-assisted self-assembly and post-carbon coating method.The obtained three-layer hierarchical structure effectively accommodates the volumetric expansion of SiO2 and significantly enhances the electronic conductivity of composite materials.Moreover,the outer layer of amorphous carbon effectively increases the diffusion rate of lithium ions and promotes the formation of stable SEI film.As a result,the SiO2/O’MCMB/C composite exhibits superior electrochemical performance with a reversible capacity of 459.5 mA h/g in the first cycle,and the corresponding Coulombic efficiency is 62.8%.After 300 cycles,the capacity climbs to around 600 mA h/g.This synthetic route provides an efficient method for preparing SiO2 supported on graphite with excellent electrochemical performance,which is likely to promote its commercial applications.
基金Supported by Shenzhen Science and Technology Innovation Committee in China(No.JCYJ20120831154554508No.JCYJ20140415174819509+1 种基金No.GJHZ20160229170608241)Medical Science and Technology Research Fund Project in Guangdong Province(No.A2015315)
文摘AIM： To characterize whether a glaucoma model with chronic elevation of the intraocular pressure （IOP） was able to be induced by anterior chamber injection of microbeads in rabbits.METHODS： In order to screen the optimal dose of microbead injection, IOP was measured every 3d for 4wk using handheld applanation tonometer after a single intracameral injection of 10 μL, 25 μL, 50 μL or 100 μL microbeads （5×10^6 beads/mL; n=6/group） in New Zealand White rabbits. To prolong IOP elevation, two intracameral injections of 50 μL microbeads or phosphate buffer saline （PBS） were made respectively at days 0 and 21 （n=24/group）. The fellow eye was not treated. At 5wk after the second injection of microbeads or PBS, bright-field microscopy and transmission electron microscopy （TEM） were used to assess the changes in the retina. The expression of glial fibrillary acidic protein （GFAP） in the retina was evaluated by immunofluorescence, quantitative real-time polymerase chain reaction and Western blot at 5wk after the second injection of microbeads.RESULTS： Following a single intracameral injection of 10 μL, 25 μL, 50 μL or 100 μL microbead, IOP levels showed a gradual increase and a later decrease over a 4wk period after a single injection of microbead into the anterior chamber of rabbits. A peak IOP was observed at day 15 after injection. No significant difference in peak value of IOP was found between 10 μL and 25 μL groups （17.13±1.25 mm Hg vs 17.63±0.74 mm Hg; P=0.346）. The peak value of IOP from 50 μL group （23.25±1.16 mm Hg） was significantly higher than 10 μL and 25 μL groups （all P〈0.05）. Administration of 100 μL microbead solution （23.00±0.93 mm Hg） did not lead to a significant increase in IOP compared to the 50 μL group （P=0.64）. A prolonged elevated IOP duration up to 8wk was achieved by administering two injections of 50 μL microbeads （20.48±1.21 mm Hg vs 13.60±0.90 mm Hg in PBS-injected group; P〈0.05）. The bright-field and TEM were used to assess the changes of retinal ganglion cells （RGCs）. Compared with PBS-injected group, the extended IOP elevation was associated with the degeneration of optic nerve, the reduction of RGC axons （47.16%, P〈0.05） and the increased GFAP expression in the retina （4.74±1.10 vs 1.00±0.46, P〈0.05）.CONCLUSION： Two injections of microbeads into the ocular anterior chamber of rabbits lead to a prolonged IOP elevation which results in structural abnormality as well as loss in RGCs and their axons without observable ocular structural damage or inflammatory response. We have therefore established a novel and practical model of experimental glaucoma in rabbits.
文摘In this paper, Fe-doped TiO_2 photocatalyst supported on hollow glass microbeads(Fe-TiO_2 /beads)is prepared by dip-coating method, which uses hollow glass microbeads as the carriers and tetrabutylorthotitanate [Ti(OC_4H_9)_4] as the raw material. The phase structure, ingredient, morphologies, particle size and shell thickness of the products are characterized by X-ray powder diffraction(XRD), energy-dispersive spectroscopy(EDS) and field emission scanning electron microscope(FESEM). The feasibility of photocatylic degradation of Rhodamine B(Rh B) under illumination of UV-vis light is studied. The results show that the core-shell structure catalyst is composed of Fe-doped anatase TiO_2 and hollow glass microbeads, and the catalytic activity of the TiO_2 is markedly enhanced by Fe ion doping. The optimum concentration of Fe ion is 0.1%(molecular fraction) in the precursor and the photocatalytic activity can be increased to 98% compared with that of the undoped one. The presence of ferrum elements neither influences the transformation of anatase to rutile, nor creates new crystal phases. The possible mechanism of photocatalytic oxidation is also discussed.
基金National Natural Science Foundation of China(Grant No.52035012)Fundamental Research Funds for the Central Universities(2682020ZT91)+1 种基金Basic Research Foundation Key Project of Sichuan Province(2021JY0046)Basic Research Foundation of Sichuan Province(2022JDRC0088).
文摘The utilization of Calcium Phosphate Cement(CPC)is limited due to its low mechanical strength and difficulty to seed cells deep into the scaffold.The objectives of this study were to:(1)develop a 3D-printed CPC-dopamine-metformin scaffold encapsulating human periodontal ligament stem cells(hPDLSCs),(2)investigate the effect of dopamine on the performance of CPC,and(3)evaluate the effect of microbead degradation and metformin release on the osteogenic differentiation of the released hPDLSCs.The mechanical property of the CPC scaffolds was elevated by adding dopamine,and the CPC scaffold with 7 wt.%dopamine had the highest compressive strength(7.35 MPa).Four types of microbeads with different content of alginate(oxidized alginate),hPDLSCs,and 2%metformin were fabricated.Morphological and cell counting kit tests confirm that the hPDLSCs are protected by microbeads encapsulation during the CPC setting process.The alkaline phosphatase test indicates that the osteogenic differentiation of hPDLSCs was enhanced by the fast release of cells and metformin.The microbeads consisting of 2%oxidized alginate and 2%metformin were optimal for cell delivery due to favorable cell release and osteogenic differentiation.This CPC scaffold is promising used for bone regeneration in dental,craniofacial,and orthopedic applications.
基金financially supported by the National Natural Science Foundation(NSFC)of China(No.22179094)。
文摘Dual-ion batteries(DIBs)have attracted tremendous attention owing to their high operating voltage and are considered promising candidates for low-cost clean energy storage devices.However,the decomposition of electrolytes and collapse of the cathode structure may lead to low Coulombic efficiency(CE)and low cycling stability of DIBs.Wide-layered electrode materials can accommodate the intercalation/deintercalation of large anions,which is believed to overcome these issues.Herein,expanded mesocarbon microbeads(200HRO-MCMB)possessing an enlarged interlayer spacing(0.405 nm)were prepared via modified Hummers and subcritical hydrothermal reduction methods.After the indispensable electrochemical activation,200HRO-MCMB(hydrothermal reduction at 200℃)exhibited a high specific capacity(120 mAh·g^(-1)at50 mA·g^(-1))when used as a cathode for a sodium-based DIB,and the CE significantly improved within the 2.0-4.5 V voltage range.Additionally,the cycling stability exceeded over 600 cycles.Remarkably,this cathode possessed enlarged interlayers that decreased the barrier of PF6^(-)transport,and the battery storage mechanism corresponded to a transitioning state between double-layer capacitance and Faradaic intercalation.Undoubtedly,this work will expand the scope of the practical application of low-cost sodium-based DIBs.
文摘Rigid PSDVB microbeads have been modified with poly(vinyl alcohol) (PVA) adsorbed on their surface to produce an affinity medium. Then Cibacron Blue F3GA was covalently attached to the supports. The initial concentration of PVA has effect on the adsorption of PVA. The non-specific interaction of bovine serum albumin (BSA) on the microbeads decreases with the PVA adsorbed. The pH stability test shows that the affinity medium is stable up to pH 11.0. And it has specific interaction with lysozyme, but not with pepsin.
文摘AIM： To investigate the effect of microbead iridocorneal angle occlusion on intraocular pressure（IOP） diurnal fluctuation in rat eyes. METHODS： Male Dark Agouti（DA） rats, 8-10 week old, were each given a single intracameral injection of microbeads, followed by injection of dispersive viscoelastic solution. The right eye served as the experimental eye, while the left eye served as the control. IOP was measured twice daily postoperatively for 3 wk and compared between groups. At the end of 3 wk, the rats were sacrificed and the eyes were harvested for histological analysis and retinal ganglion cell（RGC） counting. RESULTS： After microbead injection, experimental eyes had significantly higher dark time IOP than controls from the second week to the third week [2 nd week： 22.92±1.631 mm Hg（n=5） vs 17.35±0.751 mm Hg（n=5）; 3 rd week： 23.59±1.494 mm Hg vs 17.73±0.592 mm Hg（n=5）], while light time IOP was comparable between groups. The fluctuation levels of IOP in the experimental eyes were 7.21±0.398 mm Hg（n=5）, 9.50±1.017 mm Hg（n=5） and 10.66±0.894 mm Hg（n=5） from the first week to the third week after injection. Comparatively, they were significantly lower in the control eyes, which were 4.69±0.323 mm Hg（n=5）, 2.84±1.122 mm Hg（n=5） and 4.98±0.603 mm Hg（n=5） respectively. However, at the end of 3 wk, the larger fluctuations in IOP in the experimental eyes was not associated with a significant loss of RGCs. CONCLUSION： Microbead occlusion exacerbates diurnal IOP fluctuation in rats. This reported model may serve as a method of investigating the pathological effects of IOP fluctuation. A longer observation period, or repeated injections, may be needed to observe a significant change in RGC density.
文摘Optical magnetic twisting cytometry and traction force microscopy are two advanced cell mechanics research tools that employ optical methods to track the motion of microbeads that are either bound to the surface or embedded in the substrate underneath the cell.The former measures rheological properties of the cell such as cell stiffness,and the latter measures cell traction force dynamics.Here we describe the principles of these two cell mechanics research tools and an example of using them to study physical behaviors of the living cell in response to transient stretch or compression.We demonstrate that,when subjected to a stretchunstretch manipulation,both the stiffness and traction force of adherent cells promptly reduced,and then gradually recover up to the level prior to the stretch.Immunofluorescent staining and Western blotting results indicate that the actin cytoskeleton of the cells underwent a corresponding disruption and reassembly process almost in step with the changes of cell mechanics.Interestingly,when subjected to compression,the cells did not show such particular behaviors.Taken together,we conclude that adherent cells are very sensitive to the transient stretch but not transient compression,and the stretch-induced cell response is due to the dynamics of actin polymerization.
基金Project supported by the National Natural Science Foundation of China(No.21573239)the Guangdong Provincial Project for Science and Technology(Nos.2014TX01N14,2015B010135008,and 2016B010114003)+1 种基金the Guangzhou Municipal Project for Science and Technology(No.201509010018)the K.C.WONG Education Foundation,China。
文摘The graphene/mesocarbon microbead(MCMB)composite is assessed as an anode material with a high capacity for lithium-ion batteries.The composite electrode exhibits improved cycling stability and rate capability,delivering a high initial charge/discharge capacity of 421.4 mA·h/g/494.8 mA·h/g as well as an excellent capacity retention over 500 cycles at a current density of 40 mA/g.At a higher current density of 800 mA/g,the electrode still retains 35%of its initial capacity which exceeds the capacity retention of pure graphene or MCMB reference electrodes.Cyclic voltammetry and electrochemical impedance spectroscopy reveal that the composite electrode favors electrochemical kinetics as compared with graphene and MCMB separately.Superior electrochemical properties suggest a strong synergetic effect between highly conductive graphene and MCMB.
基金the National Natural Science Foundation of China(No.21075082)the National High Technology Research and Development Program(863) of China(No.2012AA020103)+3 种基金the Shanghai Nano Program(No.11nm0505600)the Shanghai Jiao Tong University Funding(No.YG2012ZD03)the 2012 Shanghai Jiao Tong University and University of Michigan Collaborative Research Projects(No.12X120010007)the Shanghai Municipal Education Commission Project(No.14ZZ023)
文摘Well-defined raspberry-like magnetic microbeads （RMMBs） as immunoassay solid carriers were pre- pared by chemicM covalent binding between Fe304 magnetic microspheres and SiO2 nanoparticles. These RMMBs were not as agglomerative as nano-sized magnetie particles （〈 200 nm）, which was an advangtage for high efficient magnetic separation. When compared to Fe304@SiO2 core-shell magnetic microbeads （CMMBs） with smooth surface, RMMBs exhibited stronger capacity to bind biomolecules. Limit of blank （LOB） and limit of detection （LoD） of HBsAg detection using RMMBs as carriers via chemiluminiscence immunoassay （CLIA） were 0.472 and 1.022 μg/L, respectively, showing a notable improvement compared with CMMBs whose LoB and LoD were 1.017 and 1.988 μg/L, respectively. All these indicated a great potential of RMMBs in immunoassay application.
基金Supported by the National Natural Science Foundation of China(No.51202160)
文摘Polystyrene （PS） @SiO2 core-shell microbeads with large pore and large particle size were prepared via layer-by-layer（LBL）assembly technique for potential applications in nano-micro composites. Negative silica nanoparticles synthesized via modified St6ber method and cationic poly （diallyldimethylammonium chloride） were alternately adsorbed on the surface of microbeads. Zeta potential, size, and morphology of the microbeads were monitored during LBL assembly process to ensure the successful deposition of silica nanoparticles. The porous shell was characterized using nitrogen adsorption and desorption analyses, and the surface area, volume and diame- ter of the pores were derived. It is found that the porous shell thickness and the pore size can be tuned by changing the coating times of silica nanoparticles. Finally, PS@SiO2 core-shell microbeads with 5 grn PS solid core and 350 nm mesoporous shell （mean BJH pore diameter is ~27 nm） were used to load CdSe/ZnS quantum dots （QDs）. The fluorescence microscopic image and the optical amplification of the QDs-embedded microbeads （QDBs） indicate that the as-prepared core-shell microbeads can provide adequate space for QDs and may be useful for further application of nano-micro composites.
文摘The amount of microbeads ingested by Daphnia magna decreases on exposure to toxic materials; tins oenawor was used to develop a toxicity test. To determine the toxicity of seven metals, D. magna were collected and homogenized, and the fluorescence intensity of the microbeads ingested by D. magna was measured. The amount of ingestion was determined from fluorescence intensity. The fluorescence intensity was half of that of the controls which was measured as the 30 min-FI50, and these data correlated well with those from an acute immobilization method （24 h-EC50）. An advantage of the method using fluorescent beads is that an estimate of the 24 h-EC50 can be obtained.
文摘In view of the importance of dispersion agent,the amount of the crosslinking monomer and the diluent in suspension polymerization for the production of particle size narrowly distributed low-density stryene divinylbenzene copolymer microbeads(LDPS),their actions are preliminarily investigated in this paper.Experimental results indicate that when both the gelatine and polyvinyl alcohol(PVA)are used dispersion agents,the better effect is achieved,DVB is helpful to the formation of the lower density fine particles,the proportionof the DVB/St should be between 1:1-1.5:1.Compared with toluene,gasoline is the more effective diluent for the above target.
文摘The concept of microbeads and the use of plastic microbeads(as a form of micro plastic) in cosmetics were introduced. The legislations related to prohibition of plastic microbeads in cosmetics in different countries were reviewed. And the harzards and alternatives of plastic microbeads were described.
