Malvern Laser Particle Size Analyzer Research Articles

PLGA-Astragalus Polysaccharide Nanovaccines Exert Therapeutic Effect in Colorectal Cancer.

Tumor vaccines have achieved remarkable progress in treating patients with various tumors in clinical studies. Nevertheless, extensive research has also revealed that tumor vaccines are not up to expectations for the treatment of solid tumors due to their low immunogenicity. Therefore, there is an urgent need to design a tumor vaccine that can stimulate a broad anti-tumor immune response. In this work, we developed a nanovaccine (NP-TCL@APS), which includes nanoparticles loaded with colorectal cancer tumor cell lysates (TCL) and Astragalus polysaccharides (APS) into poly (lactic-co-glycolic acid) to induce a robust innate immune response. The NP-TCL@APS was identified by transmission electron microscopy and Malvern laser particle size analyzer. The killing and immune activation effects of NP-TCL@APS were evaluated in vitro. Finally, safety and anti-tumor efficacy were evaluated in the colorectal cancer tumor-bearing mouse model. We found that NP-TCL@APS was preferentially uptaken by DC and further promoted the activation of DC in vitro. Additionally, nanoparticles codelivery of TCL and APS enhanced the antigen-specific CD8+ T cell response and suppressed the growth of tumors in mouse models with good biocompatibility. We successfully prepared a nanovaccine termed NP-TCL@APS, which can promote the maturation of DC and induce strong responses by T lymphocytes to exert anti-tumor effects. The strategy proposed here is promising for generating a tumor vaccine and can be extended to various types of cancers.

Black phosphorus quantum dots induce autophagy and apoptosis of human bronchial epithelial cells via endoplasmic reticulum stress

PurposeThe board application of black phosphorus quantum dots (BP-QDs) increases the risk of inhalation exposure in the manufacturing process. The aim of this study is to explore the toxic effect of BP-QDs on human bronchial epithelial cells (Beas-2B) and lung tissue of Balb/c mice. Methods: The BP-QDs were characterized using transmission electron microscopy (TEM) and a Malvern laser particle size analyzer. Cell Counting Kit-8 (CCK-8) and TEM were used to detect cytotoxicity and organelle injury. Damage to the endoplasmic reticulum (ER) was detected by using the ER-Tracker molecular probe. Rates of apoptosis were detected by AnnexinV/PI staining. Phagocytic acid vesicles were detected using AO staining. Western blotting and immunohistochemistry were used to examine the molecular mechanisms. Results: After treatment with different concentrations of BP-QDs for 24 h, the cell viability decreased, as well as activation of the ER stress and autophagy. Furthermore, the rate of apoptosis was increased. Inhibition of ER stress caused by 4-phenyl butyric acid (4-PBA) was shown to significantly inhibit both apoptosis and autophagy, suggesting that ER stress could be an upstream mediator of both autophagy and apoptosis. BP-QD-induced autophagy can also inhibit the occurrence of apoptosis using molecules related to autophagy including rapamycin (Rapa), 3-methyladenine (3-MA), and bafilomycin A1 (Bafi A1). In general, BP-QDs activate ER stress in Beas-2B cells, which further induces autophagy and apoptosis, and autophagy may be activated as a factor that protects against apoptosis. We also observed strong staining of related proteins of ER stress, autophagy, and apoptosis proteins in mouse lung tissue following intracheal instillation over the course of a week. Conclusion: BP-QD-induced ER stress facilitates autophagy and apoptosis in Beas-2B cells and autophagy may be activated as a protective factor against apoptosis. Under conditions of ER stress induced by BP-QDs, The interplay between autophagy and apoptosis determines cell fate.

Preparation and Characterization of Cellulose Nanofibril-Waterborne Polyurethane Composite Films

To improve the performance of polyurethane films, small amounts of cellulose nanofibrils (CNF) were physically blended with a waterborne polyurethane (WPU) emulsion, and then CNF/WPU composite films were prepared by cast-coating and drying. The particle size of the emulsions and the chemical structure, micromorphology, thermal stability, mechanical properties, and water resistance of the composite films were characterized using a Malvern laser particle size analyzer, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), an electronic strength machine, water contact angle analysis (WCA), and water absorption tests, respectively. The results showed that at a low CNF content of 0.3 wt%, the particle size of the WPU emulsion and chemical structure of the film did not change significantly. In addition, the tensile strength of the composite film increased by up to 108% compared to the neat WPU film, and the thermal stability and water resistance were slightly improved. The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film, which may greatly improve the service life and tear resistance of commercial coatings in the future.

The coupled mixing action of the jet mixer and swirl mixer: An novel static micromixer

The development of high-performance static mixers is a critical research topic in process intensification in the process industry. This research combines computational fluid dynamics simulation and experimental testing to design a new type of static micromixer: First, a variable-diameter swirl shear mixer was designed and its structure was optimized. Measured by Malvern laser particle size analyzer, the median particle size decreased from 41 μm to 29 μm in the designed micromixer compared to that of traditional static mixers. Subsequently, the dispersed phase injection method was upgraded to a jet injection method, and the static micromixer was designed with a combination of an ejector and a variable-diameter swirl shear mixer. The median particle size of the dispersed droplets further decreased to 23 μm, achieving a dispersion effect at 2100−2400 rpm of the dynamic high-shear mixer. The micromixer greatly improved the static mixing effect and may replace dynamic high-shear mixers in the future.

Enhanced luminescence and paramagnetic properties of Gd2O3:Tb3+ multifunctional nanoparticles by K+/Co2+ doping

Multifunctional Gd2O3:Tb3+ nanoparticles doped with different concentrations of K+/Co2+ were synthesized by polyol method. The samples were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), field emission scanning electron microscope (SEM), X-ray energy spectrometer (EDS), Malvern laser particle size analyzer, transmission electron microscope (TEM), photoluminescence spectrometer (PL), vibrating sample magnetometer (VSM) and magnetic resonance imager (MRI). The results showed that the synthesized spherical particles were cubic crystals with a diameter of 12–15 nm. Significant increase in fluorescence intensity was observed for Gd2O3:Tb3+ doped with K+/Co2+ ions. The optimal doped ion concentrations were found to be 3 mol% K+ ions and 4 mol% Co2+ ions, and the corresponding absolute quantum yields (QYs) were 7.21% and 5.90%. The maximum magnetization was obtained for the sample doped with 3 mol% K+/Co2+ ions. The ion-doped samples showed enhanced r1 relaxivity of water protons. Therefore, the multifunctional nanoparticles Gd2O3:Tb3+ doped with K+/Co2+ ions can potentially be used in displays, luminescence and MR bimodal imaging, sensors, magnetic separat, and other applications.

Effects of co-current airflow on water atomization in a curved diffuser

To explore the effect of airflow on water atomization mechanism in mine exhaust heat recovery system, an experimental study of the dispersed phase fraction for droplets is conducted by Malvern laser particle size analyzer. This paper focuses on the influence of gas disturbance on water atomization in a curved diffuser in a ventilation system. With the theory of liquid breakup, it shows how liquid sheet occurs in primary breakup under different operating conditions. In case that the spray flows in the same direction as the airflow, the dominant factor affecting the breakup length of liquid film near the atomizing nozzle is the injection pressure. At a long distance from the nozzle, the droplet goes through vibrational shape oscillation and eventually further breakup in the complete atomization area. The main conclusions are as follows: (1) the dispersed phase fraction for droplets reaches maximum when the airflow is 3.2 m3/s; (2) droplets achieve the optimal atomization effect of the spray; (3) the heat and moisture should be fully exchanged.

Effects of bubbles in the liquid jet on the air-blast atomization

The air-blast atomization with bubbles in the liquid jet was investigated using the high-speed camera and Malvern laser particle size analyzer. The gas was aerated into the liquid jet to form the gas-liquid mixture, which would be atomized by the co-flowing air stream. Results show that droplet size D32 decreases at the beginning and then increases with the volumetric flow rate of the aerating gas. A formula was derived to delineate the nonmonotonic trend of the droplet size. The relative deviations between the predicted results and experimental results are less than ±5%. A contour map describing the dependence of the droplet size on the aerating gas, liquid jet, and co-flowing air stream was obtained, which could provide some guidance for the further investigations and industrial applications.

PREPARATION AND CHARACTERIZATION OF CELLULOSE NANOFIBERS ISOLATED FROM LETTUCE PEEL

Abstract: Cellulose nanofibers (CNFs) were isolated from lettuce peel using specific chemical treatments, i.e., NaOH alkali solution treatment, NaClO2 bleaching and sulfuric acid hydrolysis. Both cellulose and cellulose nanofibers were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Morphological features and particle size distribution of cellulose and nanostructures were explored using transmission electron microscopy (TEM), scanning electron microscope (SEM) and the Malvern laser particle size analyzer. Results showed that particle diameters of the majority of morphological nanofibrillated cellulose were in the range of 10 to 20 nm, and length between 190 to 460 nm. The crystallinity index reached 41.57%, which increased by 117.3% compared with the raw material. The crystalline type of lettuce peel nanofibers belongs to cellulose type I. Moreover，thermal degradation temperature of CNFs is 271.7 °C which is 47.3 °C higher than that of the untreated peel. The CNFs obtained from these treatments can be used as additional biocomposites in reinforced polymer manufacturing processes or the food industry.

Experimental and numerical analysis of the spray characteristics of biodiesel–ethanol fuel blends

The effects of adding ethanol on the macroscopic and microscopic spray characteristics of biodiesel were investigated by experimental and numerical methods. The spray tip penetration (STP) was recorded with a high-speed camera system, while the statistical size distribution of atomized droplets and the Sauter mean diameter (SMD) were obtained using a Malvern laser particle size analyzer. The spray calculation models were established with Fluent software, and the calculation results were validated by the experimental results. Then the numerical simulation of the spray characteristics for diesel, biodiesel, and biodiesel–ethanol fuel blends were conducted. The results showed that the farther the distance is from the nozzle exit, the lower the concentration and the velocity of atomized droplets. The concentration and the velocity of atomized droplets gradually decrease along the radial direction, extending from the center to the periphery. The turbulent kinetic energy (TKE) at the front and rear of the spray is relatively lower, while the TKE is higher in the middle of the spray, and turbulent vortices appear on both sides of the axial spray center. In addition, the spray characteristics of the different fuels revealed that compared to diesel, the STP and SMD of biodiesel increase by 33.59% and 33.08% on average, respectively. The maximum concentration of biodiesel is higher than that of diesel, and the concentration distribution is more concentrated. The droplet velocity and TKE of biodiesel respectively decrease by 7.38% and 14.49% in comparison to diesel. When ethanol was added to biodiesel by a volume percentage of 30%, the STP and SMD of biodiesel–ethanol fuel blends reduce by 22.05% and 20.88%, respectively. The concentration distribution, the velocity distribution, and the TKE distribution of the fuel blends are similar to that of diesel. This indicates that adding 30% ethanol to biodiesel can effectively improve its spray quality.

Preparation of Nano-Fe3O4/Nylon Composite Fabric with Magnetic Properties by Post Finishing Method

In this paper, the functional nano-Fe3O4 composite fabrics with good magnetic properties were fabricated through a combined chemical co-precipitation and finishing method. The particle size and magnetic properties of Fe3O4 were measured using Malvern Laser Particle Size Analyzer and vibrating sample magnetometer (VSM), respectivily. The structure, magnetic flux and mechanical property of the composite fabric were characterized by Fourier infrared spectrometry (FT-IR), X-ray diffraction (XRD), Tesla meter and Instron electronic tensile machine. The particle-size of prepared Fe3O4 is nano-scale and has excellent magnetic properties. The nano-Fe3O4/nylon composite fabrics have good magnetism, mechanical property and water repellency. The maximum magnetic flux of nano-Fe3O4 composite fabric is 2.4 mT.

Separation performance of new type of multi-stage axial cyclone used as demister in power plant emission system

This paper presents an investigation of the performance of a multi-stage axial flow cyclone used as a demister in power plants to reduce pollution emissions. Four axial cyclones with different structural parameters were studied by numerical simulation and verification experiments. A numerical model of a two-phase flow in the cyclone separator was established and the separation efficiency and pressure loss of cyclone separators were simulated by employing the Reynolds stress model (RSM) for turbulence modeling. A test rig was constructed and the diameter distributions of droplets at the inlet and outlet of the separator were measured by a Malvern laser particle size analyzer to verify the simulation model. The results indicated that a multi-stage swirler can improve the tangential velocity to strengthen the gas swirling in the cyclone body effectively, thereby improving the separation efficiency of the cyclone. The effects of the multi-stage swirler on the flow field were analyzed, for a better understanding of the mechanisms of the flow field in the separation region for improved performance. The tangential velocities of cyclones Sep-C and Sep-B were found to be 1.5 to 2 times higher than that of the single-stage cyclone Sep-O, although the separation efficiency of Sep-C was reduced significantly when the velocity was greater than 7.9 m/s. Based on the results of this study, cyclone Sep-B was considered to be the best performing axial-flow cyclone within the acceptable pressure drop range and was proposed as a demister in power plant.

Effect of the injection pressure and orifice diameter on the spray characteristics of biodiesel

The purpose of this study was to analyze the influence of the injection pressure and orifice diameter on the spray characteristics of soybean biodiesel. The macroscopic spray characteristics of the spray tip penetration (STP) and spray cone angle (SCA) were tested with a high-speed camera system. The microscopic spray characteristics, such as the statistical size distribution, Sauter mean diameter (SMD), representative diameters and dispersion boundary, were obtained using a Malvern laser particle size analyzer (PSA). The test results showed that with an increasing injection pressure, the STP and the SCA of the biodiesel increased, but the curves of size-volume distribution and cumulative volume distribution of the atomized droplets shifted to smaller diameters. The SMD and representative diameters decreased, and the dispersion boundary was reduced. Moreover, with a decreasing orifice diameter, longer STP and smaller SCA values were observed. Similarly, the size distribution curves of the atomized biodiesel droplets shifted to smaller diameters. The SMD and representative diameters were reduced, and the relative size range of the atomized biodiesel droplets was enlarged. Higher injection pressures and smaller orifice diameters improved the biodiesel atomization; however, the smaller orifice diameters caused an inhomogeneous size distribution of the atomized biodiesel droplets.

Analysis of Characteristics of Swirling Spray of the Ammonium Dinitramide (ADN)-Based Green Monopropellant

Ammonium dinitramide (ADN) based green propellant is a promising alternative propellant for future space propulsion. Atomization of thruster plays an important role in the entire operation process. This paper describes the effect of swirl injection regarding tangential hole geometric parameter on the atomization characteristics of ADN-based green monopropellant. The experimental apparatus was prepared using a high-speed camera equipped with a macro lens and a Malvern laser particle size analyzer, and an injection device was designed. Characteristics features including particle-size distribution, spray cone, and breakup length of tangential hole number were recorded, and the effect of key parameters on spray processes was evaluated. The results show that the designed swirl injector completely achieved the atomization characteristics. With the increase in tangential hole number, the flow resistance increased, thus significantly affecting the atomization performance. The corresponding average particle size decreased. Moreover, a very large or small tangential hole number clearly affected the breakup length, spray cone angle, and average particle size. The optimum tangential hole diameter was 0.9 mm. The results are beneficial for the improvement of design structure of swirl nozzle based on ADN-based green monopropellant.

Synthesis of amphiphilic block copolymer of PLGA-b-(PEI-co-PEG) and characterization of the self-assembled cationic micelles

To synthesize a biodegradable and minimally cytotoxic amphiphilic block copolymer of PLGA-b-(PEI-co- PEG) and study its micellization behavior. PLGA was synthesized by ring-opening polymerization. The cross-linked copolymer of PEI-co-PEG was synthesized from the low-molecular-weight polyethyleneimine (PEI, 1800 D) and hydrophilic poly(ethylene glycol) (PEG, 2000 D). PLGA-b-(PEI-co-PEG) was synthesized by dehydration condensation reaction of PLGA and water soluble PEI-co-PEG. The biodegradability of PEI-co-PEG was evaluated according to the molecular weight change after incubation at 37 ℃ for different time. The cytotoxicity of PLGA- b-(PEI-co-PEG) and PEI-co-PEG in MCF-7 cells was determined by MTT assay. The cationic PLGA-b-(PEI-co-PEG) micelles were prepared by standard dialysis method. The particle size and Zeta potential of the micelles were measured by a Malvern laser particle size analyzer. Micelle/insulin complexes were prepared by simple mixing method and their morphology were characterized by transmission electron microscopy (TEM). The fluorescence quenching method was used to determine the stability of the micelle/insulin complexes at different salt concentrations. Amphiphilic block copolymer of PLGA-b-(PEI-co-PEG) was successfully synthesized. The half-life of PEI-co-PEG degradation in PBS at 37 ℃ was about 48 h. The 50% cell inhibiting concentration (IC50) of PLGA-b-(PEIco- PEG) and PEI-co-PEG in MCF-7 cells were 1375.7 μg/mL and 425.1 μg/mL, respectively. The micelles of PLGA-b-(PEI-co- PEG) (particle size: 99.5±2.61 nm, Zeta potential: 52.9±2.38 mV) were complexed with insulin via electrostatic interaction and formed nanoscale micelle/insulin complexes. The dissociation rate of micelle/insulin complexes in 150 mmol/L NaCl solution was 27.6%. The synthesized PEI-co-PEG shows good degradability in vitro. The cytotoxicity of PLGA-b-(PEI-co- PEG) is significantly lower than PEI-co-PEG, and PLGA-b-(PEI-co-PEG) micelle/insulin complexes have good salt- resistant stability in physiological condition.

Synthesis, Characterization of Nano-β-Tricalcium Phosphate and the Inhibition on Hepatocellular Carcinoma Cells

It is difficult to synthesize nano-β-tricalcium phosphate (nano-β-TCP) owing to special crystal habit. The aim of this work was to synthesize nano-β-TCP using ethanol-water system and characterize it by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Malvern laser particle size analyzer, and transmission electron microscope (TEM). In addition, the inhibitory effect of nano-β-TCP on human hepatocellular carcinoma (HepG2) cells was also investigated using MTT assay, lactate dehydrogenase (LDH) leakage test, and 4′-6-diamidino-2-phenylindole (DAPI) staining. The results showed that negatively charged rod-like nano-β-TCP with about 55 nm in diameter and 120 nm in length was synthesized, and the average particle size of nano-β-TCP was 72.7 nm. The cell viability revealed that nano-β-TCP caused reduced cell viability of HepG2 cells in a time- and dose-dependent manner. These findings presented here may provide valuable reference data to guide the design of nano-β-TCP-based anticancer drug carrier and therapeutic systems in the future.

Preparation of ultrafine iron phosphate micro-powder from phosphate slag

In this experiment, ultrafine iron phosphate micro-powder was prepared by hydrothermal method which used phosphate slag as an iron source. The effects of reaction temperature, surfactants type and amount on its particle size were explored. The samples were characterized by using Malvern Laser Particle Size Analyzer (MS2000), X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX).The results showed that at 160 °C, 1 wt%CTAB, monoclinic iron phosphate micro-powder was obtained with an average particle size about 0.4 μm which also has a good dispersion in aqueous solution.

Experimental investigation of atomization characteristics of swirling spray by ADN gelled propellant

Due to the current global energy shortage and increasingly serious environmental issues, green propellants are attracting more attention. In particular, the ammonium dinitramide (ADN)-based monopropellant thruster is gaining world-wide attention as a green, non-polluting and high specific impulse propellant. Gel propellants combine the advantages of liquid and solid propellants, and are becoming popular in the field of spaceflight. In this paper, a swirling atomization experimental study was carried out using an ADN aqueous gel propellant under different injection pressures. A high-speed camera and a Malvern laser particle size analyzer were used to study the spray process. The flow coefficient, cone angle of swirl atomizing spray, breakup length of spray membrane, and droplet size distribution were analyzed. Furthermore, the effects of different injection pressures on the swirling atomization characteristics were studied.

Rheological and structural properties of tart cherry puree as affected by particle size reduction

The objective of this study was to determine the effect of micronization techniques for particle size reduction from D (v, 0.9) ≥ 800 μm to D (v, 0.9) ≤ 100 μm on the rheological and structural characteristics of tart cherry puree. Commercially frozen cherry puree was thawed and micronized using Megatron MT5000 at 15000 rpm for three cycles (M1, M2, M3; 10 min each) followed by high-pressure homogenization at 200 MPa. The particle size distribution was measured using Malvern laser particle size analyzer and total soluble and insoluble solid contents by using the AOAC official method 20.5 or 30.2. All samples were further characterized for rheology, total solids content and particle morphology. Results showed a significant reduction in apparent viscosities (2.59 Pa s to 0.0144 Pa s) with a reduction in particle size (800 μm–100 μm) and this trend was consistent in different shear rate ranges. The change in serum viscosity followed the similar trend as observed in puree viscosity with micronization. Comparative analysis of the effect of shear rate (0–1000 s−1) on viscosity showed an inverse relationship, suggesting a shear thinning behavior of the fluid. This effect on serum viscosity (0.0119 Pa s to 0.0047 Pa s) was found to be higher in the shear rate range of 0–10 s−1, as opposed to a relatively less reduction from 0.0047 Pa s to 0.0022 Pa s and 0.0015 Pa s at higher shear rates in ranges of 20–100 s−1 and 20 to 1000 s−1 respectively. The viscosity–shear rate changes were approximated by Ostwald-de Waele model (power law relation) for serum and Herschel Bulkley model for puree. The total solid content (14.20 ± 1.10 °Brix) was not significantly affected by particle size reduction. Results of this study provide useful information about the rheological properties of fruit juices/purees, which are influenced by the interactions between the dispersed phase and the serum, and are critical indicators of textural properties, mouth-feel, commercial acceptability, requirements of mixing and transport equipment.

Application of FeCl3 to Adjust Urban Sewage-Dewatered Sludge (UDSS) Containing Cationic Polyacrylamide (CPAM) for Further Dewatering

The urban sewage-dewatered sludge (UDSS) containing cationic polyacrylamide is difficult to dewater. FeCl3 was used as conditioner to adjust the UDSS. To investigate the effect and principle, the physicochemical properties of UDSS were evaluated in terms of dewatering equipment, micro electrophoresis, Malvern laser particle size analyzer, nuclear magnetic resonance analyzer, and scanning electron microscopy. Results showed that the network structure of UDSS produced by CPAM still had high negative charge, which locked much water in the flocs and resulted in the poor dewaterability of UDSS. When Fe3+ was added into the UDSS, the inner structure of sludge was destroyed by the charge neutralism and releasing more water. At the same time, because the function of precipitate produced by the hydrolytic action, the inner structure of the sludge was solidified; therefore, the compressibility of UDSS decreased. Finally, the dewaterability of UDSS was improved and the moisture content of filter cakes can be decreased to 55%.

Influence factors on activity of Ru–Zn catalysts in selective hydrogenation of benzene

Selective hydrogenation of benzene is an atom economic green route to produce cyclohexene. The control of Zn species is the key to the catalytic performance of Ru–Zn catalysts. The influences of ZnO crystals on selective hydrogenation of benzene were explored. A series of Ru–Zn catalysts with different Zn contents and ZnO morphologies were prepared by changing the amount of NaOH in the co-precipitation process. The catalysts were characterized by N2 physisorption, X-ray powder diffraction (XRD), inductively coupled plasma optical emission spectrometer (ICP-OES), scanning electron microscope (SEM), temperature-programmed reduction (H2-TPR) and Malvern laser particle size analyzer. It is found that with increasing the amount of NaOH, the Zn content first increased then decreased, and the ZnO crystals changed from relatively thicker pyramidal-shaped crystals to slimmer needle-shaped crystals. The catalyst had the highest Zn content (22.1%) and strongest interaction between ZnO crystals and Ru particles at pH10.6 of the solution after reduction. As a result, it had the lowest activity. The activity of Ru–Zn catalysts is affected by both the Zn content and the interaction between ZnO crystals and Ru particles. The effect of reduction time was also investigated. Prolonging the reduction time caused no significant growth of ZnO crystals but the aggregation of catalyst particles and growth of Ru nanocrystals, thus resulting in the decrease of catalytic activity.