Microsphere Particles Research Articles

Strengthening Study on Microsphere Particle Peening for Flexspline Surface of Harmonic Reducer

Abstract The service stability of the flexspline directly affects the service life of the harmonic reducer. Its main failure modes are fatigue fracture of the flexspline, damage of the flexible bearing, tooth wear or transmission slip, the above problems are often sprouted and developed from the surface. Researches show the novel surface treatment technology-Microsphere Particle Peening can significantly enhance the surface performance of the flexspline of the harmonic reducer, and thus improve its fatigue resistance. Therefore, studying this novel shot peening technology has significant scientific significance and practical value. In this paper, Microsphere Particle Peening is adopted to strength the flexspline surface and the effects of three different Microsphere Particle Peening conditions on the surface performance of the flexspline is analyzed. The research results indicate that Microsphere Particle Peening technology can introduce larger residual compressive stress, reduce the surface roughness, increase the surface hardness, improve the microstructure morphology, and effectively control the deformation amount of the flexspline by controlling the processing parameters of Microsphere Particle Peening. Therefore, Microsphere Particle Peening technology has broad engineering application prospects in the surface strengthening of precision components.

ROS responsive conductive microspheres loaded with salvianolic acid B as adipose derived stem cell carriers for acute myocardial infarction treatment

Stem cell therapy is currently the most promising strategy for the treatment of myocardial infarction. However, the development of injectable cell carriers that can scavenge reactive oxygen species (ROS) in the infarct zone to improve transplanted cell survival remains a challenge. Here, we developed a ROS responsive conductive microsphere based on chitosan (CS) and dextran (DEX) with 4-formylphenylboronic acid (4-FPBA) as a cross-linking agent and the addition of graphite oxide (GO) and the anti-inflammatory agent salvianolic acid B (SalB), as a cell delivery carrier for myocardial infarction. These microspheres were crosslinked by dual dynamic networks of Schiff base and phenylborate bonds. The relationship between CS concentration and microsphere particle size, as well as the biocompatibility, ROS responsiveness, anti-inflammatory properties, and effects on myogenic differentiation of H9C2 cells were fully investigated. The microspheres exhibit good biocompatibility, proliferation promoting, differentiation promoting, antioxidant, and anti-inflammatory properties. When applied to mice myocardial infarction models, the ROS responsive conductive microspheres loaded with SalB and adipose derived stem cells (ADSC) exhibited excellent in vivo repair ability. In addition, they reduced myocardial fibrosis and promoted ventricular wall regeneration by promoting the expression of Connexin 43 (Cx43) and CD31, ultimately reshaping the infarcted myocardium, suggesting their great potential as cell delivery carriers for myocardial infarction treatment.

Magnetically targeted lidocaine sustained-release microspheres: optimization, pharmacokinetics, and pharmacodynamic radius of effect

ObjectiveThis study aimed to optimize the formulation of magnetically targeted lidocaine microspheres, reduce the microsphere particle size, and increase the drug loading and encapsulation rate of lidocaine. The optimized microspheres...

Lasing emission from ZnO hierarchical spherical microcavity

We investigated lasing characteristics of ZnO hierarchical micro-spherical particles with diameters of 1–5 μm . The lasing emission consists of a small number of discrete laser peaks unlike conventional random lasing from ZnO nanopowder-assembly. Theoretical calculations based on a many-body theory reveal that the optical gain is achieved at the observed lowest lasing threshold value, 4 mJ⋅cm−2⋅pulse−1 , which corresponds to the excited carrier density ∼2.4×1025 m−3 . Because the carrier density is much higher than the Mott density, the gain origin for lasing is electron-hole plasma recombination. The lasing frequency mode shift ( ∼1.2 meV ) is due to the refractive index change induced by exciting high carrier density up to 6.1×1025 m−3 . By changing hierarchical structures via controlling growth condition and performing the annealing treatment and performing the calculation of scattering efficiency of ZnO particles, we found that the hierarchy of the micro-spherical particle plays a crucial role of the lasing feedback: the strong light scattering at the interface between outer nanoparticles with the sizes of 100–200 nm and smaller ones with the sizes of 10–60 nm consisting in the micro-spherical particle results in a light confinement. Furthermore, it has been confirmed that each discrete lasing mode shows strong gain competition with each other probably due to spatial overlap between the modes. These results suggest that both random scattering and microcavity modes contribute to the lasing oscillation.

Interfacial polarization and electrorheological effect of homo-poly(ionic liquid) and poly(ionic liquid)-hexyl methacrylate copolymer microsphere particles

Homo-poly(ionic liquid) (HomoPIL) microsphere particles of poly[2-(methacryloyloxy)ethyltrimethylammonium][bis(trifluoromethanesulfonyl)imide] (P[MTMA][TFSI]) and poly[2-(methacryloyloxy)ethyltrimethylammonium][hexafluorophosphate] (P[MTMA][PF6]), as well as their corresponding copolymer microsphere particles obtained through copolymerization with hexyl methacrylate (HMA), were synthesized as electrorheological (ER) materials. The morphology and structure of these synthesized particles were characterized using scanning electron microscopy (SEM), 1H nuclear magnetic resonance spectroscopy (1H NMR), Fourier-transform infrared spectroscopy (FT-IR), and small-angle X-ray scattering spectra (SAXS). Electrorheological measurements were conducted for these polyelectrolyte-based suspensions at room temperature, revealing that the HMA composition has a different effect on the ER effect of the two poly(ionic liquid)s. Differential scanning calorimetry (DSC) and temperature-modulated dielectric analysis (TMDA) were employed to investigate the effect of HMA composition on the glass transition temperature and interfacial polarization of these polyelectrolytes, suggesting that the incorporation of HMA affect the ER effect of PILs via changing the density of charge carriers and the counterion mobility. This study presents a potential approach for enhancing the electrorheological properties of poly(ionic liquid)s.

The effect of molecular weight of polyvinylpyrrolidone on the release of p-aminosalicylic acid from microspherical solid dispersion particles

The effect of molecular weight of polyvinylpyrrolidone on the release of p-aminosalicylic acid from microspherical solid dispersion particles

Unveiling the role of pore characteristics in sludge dewatering: Visualization by Nano-CT and micromodel study

The solid-liquid separation is an indispensable and primary link in the process of sludge treatment and disposal. The past research was focused primarily on the technique explorations of sludge dewatering and always disregarded the internal pore structure and water migration behavior in sludge. In this work, the real three-dimensional pore structure of sludge was obtained by Nano-CT. Based on this, a pore-scale heterogeneous sludge micromodel was firstly presented, and the water flooding experiment was carried out to visualize the water migration behavior. The results showed that the sludge structure transformed from sheet-like floc to microsphere particles, and then agglomerated into large globular granules during anaerobic ammonia oxidation. And the equivalent pore size increases from 342 μm to 617 μm, improving the sludge dewaterability characterized by capillary suction time (CST). The most significant implication of this work was revealing the critical role of invalid connected pore in sludge dewatering. Such pore was not contributed to fluid flow but the circulating vortex in it even induced energy dissipation, thus deteriorated the sludge dewaterability. This work may be helpful to understand the critical role of pore characteristic in water migration and shed light on the new dewatering techniques from the perspective of regulating sludge structure.

Preliminary Evaluation of Methods for Continuous Carbon Removal from a Molten Catalyst Bubbling Methane Pyrolysis Reactor

Methane pyrolysis in molten catalyst bubble (MCB) column reactors is an emerging technology that enables the simultaneous production of hydrogen and solid carbon, together with a mechanism for separating the two coproducts. In this process, methane is dispersed as bubbles into a high temperature molten catalyst bath producing hydrogen and low-density carbon, which floats to the surface of the bath from providing a means for them to be separated. However, the removal of carbon particulates from a bubbling column reactor is technically challenging due to the corrosive nature of the molten catalysts, contamination of the product carbon with the molten catalysts, high temperatures and lack of understanding of the technology options. Four potential concepts for the removal of carbon particulate from a methane pyrolysis molten metal bubble column reactor are presented, based on the pneumatic removal of the particles or their overflow from the reactor. The concepts are evaluated using a cold prototype reactor model. To simulate the operation of a high-temperature reactor at low temperatures, the dominant dimensionless numbers are identified and matched between a reference high-temperature reactor and the developed cold prototype using water, air and hollow glass microsphere particles as the representatives of the molten catalyst, gaseous phases and solid carbon particulates, respectively. The concepts are tested in the cold prototype. High rates of particle removal are achieved, but with different tradeoffs. The applicability of each method together with their advantages and disadvantages are discussed.

Circulating biomarkers of the CS4P and CLIP scores are not altered in a pig model of acute cardiogenic shock and additional short-term circulatory support

BackgroundCardiogenic shock (CS) is the leading cause of death in patients with myocardial infarction with a mortality rate greater than 50%. Recently, the CS 4 Proteins (CS4P) and CLIP scores have been developed to predict survival in CS patients. However, their impact in acute CS and additional short-term left ventricular (LV) circulatory support as prognostic markers is currently not known. Methods and resultsCS was induced in a porcine model by injecting microsphere particles into the left main coronary artery. Mechanical circulatory support was performed by additional percutaneous LV unloading using an Impella microaxial flow-pump for 30 minutes. Serum samples were collected at baseline, following the onset of CS, and additional LV unloading. Serum levels of biomarkers of the CS4P (beta-2-microglobulin, ALDOB, L-FABP, SerpinG1) and the CLIP scores (Cystatin C, Lactate, Interleukin-6, NT-proBNP) were neither different at any time point investigated nor did they correlate with cardiac output. ConclusionThe CS4P and CLIP scores do not reflect immediate whole-body dysregulation in acute CS and have not been able to predict the potential reversal following additional short-term mechanical support by LV unloading in our experimental model. The impact of both scores as prognostic markers after the immediate onset of CS and following additional short-term LV unloading to identify patients at greatest risk remains to be determined.

PLGA micro/nanoparticle vaccination elicits non-tumor antigen specific resident memory CD8+ T cell protection from hepatocellular carcinoma.

Together, tumor and virus-specific tissue-resident CD8+ memory T cells (TRMs) of hepatocellular carcinoma (HCC) patients with Hepatitis B virus (HBV) infection can provide rapid frontline immune surveillance. The quantity and activity of CD8+ TRMs were correlated with the relapse-free survival of patients with improved health. However, HBV-specific CD8+ TRMs have a more exhausted phenotype and respond more actively under anti-PDL1 or PD1 treatment of HBV+HCC patients. Vaccination strategies that induce a strong and sustained CD8+ TRMs response are quite promising. Herein, a biodegradable poly(D,L-lactide-co-glycolide) microsphere and nanosphere particle (PLGA N.M.P) delivery system co-assembled by anti-PD1 antibodies (aPD1) and loaded with ovalbumin (OVA-aPD1 N.M.P) was fabricated and characterized for size (200 nm and 1 μm diameter), charge (-15 mV), and loading efficiencies of OVA (238 μg mg-1 particles) and aPD1 (40 μg mg-1 particles). OVA-aPD1 N.M.P could stimulate the maturation of BMDCs and enhance the antigen uptake and presentation by 2-fold compared to free OVA. The nanoparticles also induced the activation of macrophages (RAW 264.7) to produce a high level of cytokines, including TNF-α, IL-6 and IL-10. In vivo stimulation of mice using OVA-aPD1 N.M.P robustly enhanced IFN-γ-producing-CD8+ T cell infiltration in tumor tissues and the secretion of IgG and IgG2a/IgG1 antibodies. OVA-aPD1 N.M.P delivered OVA to increase the activation and proliferation of OVA-specific CD8+ TRMs, and its combination with anti-PD1 antibodies promoted complete tumor rejection by the reversal of tumor-infiltrating CD8+ T cell exhaustion. Thus, PLGA N.M.P could induce a strong CD8+ TRMs response, further highlighting its therapeutic potential in enhancing an antitumor immune response.

A facile strategy for the preparation of polylactide nano-microspheres with enhanced stereo-complexations.

Stereo-complexed polylactide (sc-PLA) nano-microspheres were separated by adding poor solvent to the poly(l-lactide) (PLLA)/poly(d-lactide) (PDLA) blend solution. The effects of different process parameters (concentration, processing method, ratio of PLLA/PDLA blend solution to poor solvent) on the microsphere particle size were investigated. The microscopic morphology, crystallinity, and thermal properties were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, two-dimensional wide-angle X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The results indicated that when the concentration reached 10 wt% and the PLLA/PDLA blend solution to poor solvent ratio was 1 : 5, the sc-PLA nano-microspheres exhibited more regular shape, good sphericity and uniform particle size, and the highest crystallinity. Additionally, the degree of crystallinity of the stereo-complexed crystals was as high as 39.60%, the rate of stereo-complexation was 99.65%, and the melting temperature reached 220 °C, indicating notable improvement in the crystallization and thermal properties. The sc-PLA nano-microspheres obtained in this research could be used as a nucleating agent for fibers and drug delivery carrier, and the sc-PLA nano-microspheres have broad application prospects in the textile and biomedical fields.

Home-made optical tweezers for biomedical applications

Optical tweezers has been built with confocal fluorescence microscope as based detection. Microsphere particles and 780 nm fluorescence dye molecules are used in our demonstration. With the combination between these two particles, light focusing and particle manipulation can be performed simultaneously. The experimental results show that the tweezers can trap and move particles and even rotate the clusters of dye molecules sharply. We aim to apply our tweezers to biomedical applications such biological samples in the near future.

Single Infrared Spectrum Enables Simultaneous Identification of (Bio)Chemical Nature and Particle Size of Microorganisms and Synthetic Microplastic Beads.

Populations of nearly identical chemical and biological microparticles include the synthetic microbeads used in cosmetic, biomedical, agri-food, and pharmaceutical industries as well as the class of living microorganisms such as yeast, pollen, and biological cells. Herein, we identify simultaneously the size and chemical nature of spherical microparticle populations with diameters larger than 1 μm. Our analysis relies on the extraction of both physical and chemical signatures from the same optical spectrum recorded using attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectroscopy. These signatures are the spectral resonances caused by the microparticles, which depend on their size and the absorption peaks revealing their chemical nature. We validate the method first on separated and mixed groups of spherical microplastic particles of two different diameters, where the method is used to calculate the diameter of the microspherical particles. Then, we apply the method to correctly identify and measure the diameter of Saccharomyces cerevisiae yeast cells. Theoretical simulations to help in understanding the effect of size distribution and dispersion support our results.

Polyurethane Acrylate Oligomer (PUA) Microspheres Prepared Using the Pickering Method for Reinforcing the Mechanical and Thermal Properties of 3D Printing Resin

Some photosensitive resins have poor mechanical properties after 3D printing. To overcome these limitations, a polyurethane acrylate oligomer (PUA) microsphere was prepared using the Pickering emulsion template method and ultraviolet (UV) curing technology in this paper. The prepared PUA microspheres were added to PUA-1,6-hexanediol diacrylate (HDDA) photosensitive resin system for digital light processing (DLP) 3D printing technology. The preparation process of PUA microspheres was discussed based on micromorphology, and it was found that the oil-water ratio of the Pickering emulsion and the emulsification speed had a certain effect on the microsphere size. As the oil-water ratio and the emulsification speed increased, the microsphere particle size decreased to a certain extent. Adding a suitable proportion of PUA microspheres to the photosensitive resin can improve the mechanical properties and thermal stability. When the modified photosensitive resin microsphere content was 0.5%, the tensile strength, elongation at break, bending strength, and initial thermal decomposition temperature were increased by 79.14%, 47.26%, 26.69%, and 10.65%, respectively, compared with the unmodified photosensitive resin. This study provides a new way to improve the mechanical properties of photosensitive resin 3D printing. The resin materials studied in this work have potential application value in the fields of ceramic 3D printing and dental temporary replacement materials.

Selective Transarterial Embolization for Intractable Hematuria Due to Bladder Carcinomas: A Single-Center Experience.

Malignant bladder neoplasms can cause life-threatening persistent hematuria. Selective transarterial embolization is an effective way to achieve hemostasis in such patients. The purpose of our study is to share our experience in these patients and to evaluate the short- and long-term effectiveness of this procedure. Twelve male patients with intractable hematuria due to bladder carcinoma were included in the study. A total of 17 selective transarterial embolization procedures (bilateral in 5 patients) were performed in 12 patients with microspherical particles and microcoils. Complete control of bleeding was achieved in 9 patients after the procedures whereas the need for transfusion continued in 3 patients. Approximately 75% bleeding control was achieved during our average 6-month (4- to 12-month) follow-up period. After the procedure, the patients had mild complaints that lasted for a few days, such as pain (66%), fever (42%), and nausea (50%). No major complications occurred. Selective transarterial internal iliac artery embolization is a reliable method that can be used for the palliative treatment of intractable hematuria due to bladder carcinomas.

Electromagnetic wave absorption properties of red mud-blast furnace slag based geopolymers filled with various wave-absorption materials

In this work, red mud-blast furnace slag (RM-BFS) based geopolymers with excellent electromagnetic wave absorption property is synthesized through the incorporation of wave-absorption materials. The electromagnetic absorption property of geopolymer is characterized through the arched test, in which the reflection loss of specimens is tested by vector network analyzer (VNA). The microstructure and conductivity of geopolymers are characterized through scanning electron microscopy (SEM), concrete porous structure analyzer and conductivity tester. The crystalline phase and functional groups of geopolymers are characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Compared to Portland cement concrete (PCC), wave absorption band of the geopolymer is wider and the absorption peak in high frequency band is more intense. With the optimal addition of hollow glass microsphere (HGM), Fe2O3 and graphite particles, the absorption bandwidth with reflection loss less than −5 dB are 12.4, 7.7 and 8.1 GHz, and the maximum reflection loss are −9.4, −8.4 and −8.7 dB, respectively. This study might give a clue for preparation of geopolymers with high electromagnetic wave absorption properties.

Multi-drug delivery and osteogenic performance of β-tricalcium phosphate/alginate composite microspheres

To address the insufficiencies in the systemic research of calcium phosphate/alginate (ALG) microspheres for multi-drug delivery and bone formation, this study investigated the multi-drug release kinetics and osteogenic behaviors of β-tricalcium phosphate/ALG microspheres. The results showed that different loaded drugs exhibited an early burst release phenomenon, and the drug loading capacity decreased as the microsphere particle size decreased. In vitro cell proliferation and dead/live staining demonstrated that the microspheres had excellent cytocompatibility, and in vivo experiments demonstrated the microspheres’ exceptional ability to enhance bone regeneration.

In-situ hydrothermal Mg(OH)2-SiO2-Al(OH)3 composite coatings on AZ91D magnesium alloy with enhanced corrosion properties

A one-step in-situ hydrothermal method (HT) was performed on magnesium alloys to prepare Mg(OH)2-SiO2-Al(OH)3 (MSA) composite coatings with strong corrosion resistance. In this study, the aluminum-rich Mg(OH)2 was used as the bottom layer, and SiO2-Al(OH)3 microsphere particles generated by self-assembly of strip monomers were the top layers, which together prevented the penetration of corrosive ions (Cl−) into the AZ91D surface. Due to the in-situ growth process, the adhesion between the film and the substrate stays strong, and the generation of silicate during HT further enhanced the stability of the coating, which improved its potential for practical application. Electrochemical experiments showed that the MSA composite multilayer film strengthened the corrosion resistance of AZ91D, and the corrosion current density decreased by about five orders of magnitude. The connection between particle morphology and different preparation conditions was also discussed. MAS composite coatings provide a new approach to corrosion protection of metal substrates.

Stabilization of NCM811 cathode for Li-ion batteries by N-doped carbon coating

Ternary nickel-rich layered oxide LiNi0.8Co0.1Mn0.1O2 (NCM811), as a promising next-generation cathode material for lithium-ion batteries, is still suffered from severe capacity fading triggered by irreversible phase transition and side reactions during cycling, which can be effectively circumvented by surface coating. Herein, microspheric NCM811 particles are homogeneously coated by N-doped carbon layer via a facile and low-cost rheological phase reaction method followed by low temperature sintering. The N-doped carbon coating disperses more uniformly than carbon coating on NCM811, which is attributed to the formation of NiN bond between carbon coating layer and bulk NCM811. And the introduced N element can inhibit the reduction of Ni3+ to Ni2+ on the surface of NCM811, leading to a positive effect on the suppression of cationic mixing that further improves the structural stability. Based on the electrochemical performance analyses, it is found that the surface pseudocapacitance and Li+ diffusion ability both are significantly promoted after N-doped carbon coating. Benefit from the suitable pseudocapacitive behavior and high Li+ diffusion coefficient, the NCM811-CN0.5 electrode presents a discharge specific capacity of 216.98 mAh/g at 0.1C, 151.01 mAh/g at 10C, and capacity retention of 82.3 % after 500 cycles at 5C, indicating that it will be an ideal cathode material for developing high-power and long-lifespan lithium-ion batteries.

Cu2(OH)3Cl microspheres with self-assembled nanostructures through a dissolution regulation reaction and exhibits excellent antibacterial activity

Basic copper chloride (Cu2(OH)3Cl) microspheres with different surface nanostructure were synthesized via the dissolution regulation of calcite in CuCl2 solution. We studied the influence of CuCl2 concentration, reaction time and reaction temperature on the formation of Cu2(OH)3Cl, and the products were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy. The concentration of CuCl2 has a great influence on the dissolution rate of calcite, dispersed microsphere particles assembled by nano-blocks formed in 20 mM CuCl2 solution. The surface of Cu2(OH)3Cl microsphere change from nano-block to nano-rod with increasing the reaction time from 20 min to 2 h Cu2(OH)3Cl microspheres with surface structure changed from nano-sheet, nano-plate to nano-block with the reaction temperature increase from 37 °C to 70 °C. The Cu2(OH)3Cl microsphere also displays superior antibacterial properties against S. aureus and E. coli. This work displays a new strategy to synthesize functional materials by the use of dissolution regulation methods.