Laser Particle Size Analyzer Research Articles

The Formation of Protein Corona by Nanoplastics and Horseradish Peroxidase.

In theory, nanoplastics (NPs) can adsorb biological macromolecules, such as proteins, in the surrounding environment to form protein corona (PC). In this study, we focus on amino polystyrene (PS) NPs and horseradish peroxidase (HRP) to explore the dynamic process of the formation of PS-HRP PC and their influence on PS and HRP. This work used atomic force microscopy, laser particle size and Zeta potential analyzer, and UV-vis spectrophotometer. According to the adsorption behavior of HRP to NPs, the surface morphology characteristics of NPs can be observed to change at 60 min. Meanwhile, the increase in size and hydrodynamic diameter, the decrease in Zeta potential, surface roughness and HRP activity, and the change in HRP structure attest to the PC formation. The thickness of the PC was approximately 30 nm and there are differences in the dynamic and static variations in the size of the PC. The PC formation process progresses gradually from 0 min to 240 min. Overall, the formation of PS-HRP PC is identified, and the changes in its properties are confirmed from the perspective of nanoplastics and peroxidase, which help study the effects of nanoplastics on the environment and creatures.

Enhanced removal of hexavalent chromium and nitrate in aquifers by alkali-modified emulsified vegetable oil

The cocontamination of hexavalent chromium (Cr(VI)) and nitrate is common in groundwater, particularly in plains region. Injecting emulsified vegetable oil (EVO) into aquifer is an effective method for the simultaneous removal of Cr(VI) and nitrate from groundwater. In this study, EVO and alkali-modified emulsified vegetable oil (AM-EVO) were prepared from soybean oil and magnesium hydroxide. Characterization methods such as atomic force microscope (AFM), inverted fluorescence microscope (IFM), laser particle size analysis, and Fourier transform infrared spectroscopy (FTIR) were used to examine the microscopic morphology, particle size distribution, and surface functional groups. The remediation efficiency of EVO and AM-EVO were investigated and compared for Cr(VI) and nitrate removal in groundwater. Influencing factors on the removal of Cr(VI) and nitrate such as initial dissolved oxygen, alkaline substance type, alkaline substance existing form, and reagent dosage were studied. AM-EVO with good stability, good dispersity, and high removal efficiency was obtained with the concentrations of soybean oil, magnesium hydroxide, polyoxyethylene sorbitan monooleate (Tween-80), and sodium dodecyl sulfate (SDS) were respectively 45, 25, 9.3, and 1.75 g/L. The AM-EVO could effectively accelerate the removal of contaminants at initial pH 10 and 30 °C, 10 mg/L Cr(VI) and 350 mg/L nitrate both could be completely removed within five days. Cr(VI) was reduced by microbial secondary ferrous iron, and the apparent rate constant was increased from 0.07 day−1 to 0.41 day−1. Nitrate was reduced by denitrifying bacteria, and the degradation rate constant was increased from 2.01 day−1 to 3.65 day−1.

Micromechanics prediction of dynamic modulus for asphalt mastic considering filler distribution characteristic: A new perspective

This study aims to provide a new perspective into the consideration of filler distribution characteristic in micromechanical modeling of asphalt mastic through combining fractal microstructure. To do this, three viscoelastic micromechanical models were improved by the preliminarily combination between micromechanical equivalence and fractal statistic principles. Particle size distribution (PSD) of filler was tested by a laser particle size analyzer. Asphalt mastics with different filler concentrations were fabricated. Dynamic shear moduli of asphalt and asphalt mastics was tested by a dynamic shear rheometer. The PSD of the circles intercepted by the plane and dimensionless area of the intercepted asphalt matrix were analyzed. The dynamic shear modulus ratio of asphalt mastic to binder were calculated based on the improved models. The effects of various parameters on the distribution of the ratio were investigated. Results show that the shifted R-R distribution function is capable of capturing the PSD of filler. The dimensionless area increases with increasing dimensionless diameter, but decreases with increasing filler volume fraction. The shear modulus ratio shows a three-stage reduction trend with dimensionless diameter, replying that the shear modulus of asphalt mastic appears as a random distribution in space. Meanwhile, the spatial distribution is influenced by filler volume fraction and thus there has difference between the stiffening effects of filler on various local regions in asphalt mastic. Poisson’s ratio of binder plays an enhanced role in the stiffening effect of filler, which is affected by the spatial locations within asphalt mastic. Modulus and Poisson’s ratio of limestone filler and modulus of binder have little effect on the distribution of the shear modulus ratio. The combination of micromechanical modeling and fractal characteristic is capable of determining the spatial distribution characteristic of effective properties for asphalt mastic. The local homogenization of asphalt mastic in terms of the modulus and its influence on properties of asphalt mixture should be focused on and conducted in future.

Features of SHS of multicomponent carbides

Combustion of powders of transition metals of titanium PTS (average particle size 57 μm), zirconium PCRK-1 (12 μm), tantalum Ta PM-3 (8 μm), hafnium GFM-1 (4 μm), niobium NBP-1a (21 μm) with carbon black grade P-803 dispersion 1–2 μm was studied. The combustion process of the compressed samples (mass 2.5–6.9 g, height 1.2–1.7 cm, relative density 0.55–0.61) was performed in an inert argon medium at a pressure of 760 mmHg in the constant pressure chamber. Combinations were studied, Me1 + Me2 + Me3 + Me4 + 4C, Me1 + Me2 + Me3 + Me4 + Me5 + 5C. XRD patterns of the mixtures were recorded on a DRON-3М diffractometer (CuKα-radiation). Combustion product sections were studied using a LEO 1450 VP scanning electron microscope (Carl Zeiss, Germany). The fractional composition and particle size distribution of the mixture were determined according to standard procedure using a Microsizer-201C laser particle size analyzer. Combustion velocity, elongation of samples, phase composition of products were determined. The maximum combustion temperature of the mixture (Ti + Hf + Zr + Nb + Ta) + 5C was measured experimentally for the first time. The morphology and microstructure of the reaction products were also observed. Combustion products of mixtures (Ti + Zr + Nb + Ta) + 4C and (Ti + Zr + Nb + Hf) + 4C contain high entropy carbides, which are solid solutions with the same structural type B1 (space group Fm-3m) and having different cell parameters. Product samples of mixtures (Ti + Zr ++ Hf + Ta) + 4C and (Ti + Hf + Zr + Nb + Ta) + 5C contain high entropy and medium entropy carbides, also representing solid solutions with the same structural type B1 (space group Fm-3m). The results of this work can be used in the production of high-entropy and medium-entropy multicomponent carbides.

Creep and fatigue properties of asphalt mastic with steel slag powder filler

Steel slag powder (SSP) was selected as an inorganic micro powder filler instead of limestone powder (LSP) to prepare asphalt mastic in this paper. Firstly, the microscopic characteristics of SSP and LSP such as particle size distribution, surface morphology, phase composition and chemical composition were characterized by laser particle size analyzer, scanning electron microscopy (SEM), X-ray diffraction (XRD) analyzer, and X-ray fluorescence (XRF) analyzer. Then, the composition and content of chemical functional groups of asphalt mastics were studied by fourier transform infrared spectrometer (FTIR). Finally, the effect of SSP on the creep and fatigue properties of asphalt mastics was investigated via multiple stress creep recovery (MSCR) and time scanning experiments using a dynamic shear rheometer (DSR). The results showed that the addition of SSP as mineral filler instead of LSP to asphalt binder enhanced the deformation resistance and the fatigue life of the asphalt mastics.The complex shear modulus of asphalt mastics show an increase trend with an increase in the SSP content. Compared with LSP asphalt mastic, the complex shear modulus of SSP asphalt mastic ( SSP content 30 %, 50 %, 100 %) increased by 84.9 %, 118.0 % and 256.1 %, respectively. From the perspective of structural design and material selection, the fatigue life NDER corresponding to the cumulative dissipative energy rate(DER) is recommended to analyze the fatigue life of asphalt mastics.The results of the MSCR and time scanning experiments demonstrated that the use of a combination of SSP and LSP as filler could be an effective approach for comprehensive utilization of steel slag in asphalt mixture.

Fabrication of starch-based emulsion gel beads by an inverse gelation technique for loading proanthocyanidin and curcumin

In this study, large-scale emulsion gel beads were fabricated using an inverse emulsion gelation technique. Gelation was achieved by simple starch retrogradation, which enabled dual loading of proanthocyanidin and curcumin. The properties and morphologies of the fabricated emulsion gel beads were characterized by means of laser particle size analysis, rheological measurement, texture profile analysis, optical microscopy, and scanning electron microscopy. The average size of the emulsion gel beads ranged from 2.8 to 5.9 mm. With the increase in the starch concentration from 9.1% to 33.3%, the hardness of the gel beads was increased 8.8-fold, from 195.31 ± 30.73 g to 1734.94 ± 155.17 g, whereas the swelling ratio of the beads showed a decreasing trend under different treatment conditions (pH range from 1.5 to 12 and temperature range from 25 to 80 °C). Increasing the starch concentration from 9.1% to 33.3% also resulted in a decrease in the release ratio of proanthocyanidins and curcumin from 68.32% to 16.66% and from 7.00% to 0.45%, respectively, after simulated gastric fluid digestion for 2 h, indicating that starch-based emulsion gel beads can tolerate the damage imposed by the gastric environment. Disruption of the starch gel network by amylase hydrolysis and digestion in simulated intestinal fluid for 4 h caused a cumulative release of proanthocyanidins and curcumin from the beads in excess of 75% and 28%, respectively. Therefore, starch-based emulsion gel beads, which combine the advantages of emulsion and hydrogel systems, are ideal carriers for loading hydrophilic and hydrophobic active ingredients.

Influence of injection methods on calcareous sand cementation by EICP technique

Calcareous sands are widely distributed on continental shelves, coastal zones, islands and reefs in the tropical oceans. For being used as construction materials, calcareous sands should be artificially treated to improve their engineering properties. Enzymatically induced carbonate precipitation (EICP) is an innovative soil treatment technique. In this paper, urease was extracted from soybean powder using artificial seawater for calcareous sands cementing by the EICP technique. Cementation tests were conducted with three injection methods (the pre-mixed, staged and proposed parallel injections) and two injection rates (2 and 5 mL/min). The hydraulic conductivity, shear wave velocity (SWV) and unconfined compressive strength tests were conducted and the cementation effects were evaluated. The hydrodynamic diameter of the particles generated in the mixed solutions was measured with reaction time by a laser particle size analyzer and the influence of injection rate on the CaCO3 distribution in the specimen was discussed. The coefficient of variation of the SWV values along the cemented specimen height was calculated for evaluation of the cementation uniformity. Results show that a high injection rate was conducive to reducing clogging and improving the cementation uniformity by completing injection within the urea hydrolysis phase. The promising parallel injection method proposed in this study provided a lag time for reaction by simultaneous injection of crude urease and cementation solutions using two separate tubes. Specimens treated at a high parallel injection rate were uniformly cemented with high mechanical strengths and high overall hydraulic conductivities because of a high proportion of CaCO3 in contact-cementing distribution.

Efficient recovery of valuable metals from waste printed circuit boards via ultrasound-enhanced flotation

Due to the environmental hazard of waste printed circuit boards (WPCBs), there is an urgent need to develop efficient recycling technology of useful metal elements in WPCBs and to promote the efficient use of WPCBs. Therefore, we tried to intensify the efficient recovery of metal elements from WPCBs by introducing ultrasound into the flotation process. Scanning electron microscope (SEM) observation and laser particle size analysis confirmed that ultrasonic treatment was conducive to removing the epoxy resin and fine metal particles on the surface of glass fibers and promoting particle dispersion, which significantly improved metal recovery. In addition, wettability analysis demonstrated that the enhanced hydrophobicity of the non-metallic components caused by ultrasonic treatment improved the flotation performance of non-metallic components, thereby strengthening the reverse flotation separation efficiency of the metal components and the non-metallic components. Consequently, compared with traditional flotation, ultrasonic-enhanced flotation promoted the significant increase of total metal recovery and Cu, Al and Zn recovery from WPCBs, in which the total metal recovery and Cu, Al and Zn recovery from WPCBs increased by 7.20%, 4.82%, 15.41% and 5.58%, respectively. Based on this, our findings will provide an important guide for efficiently recovering valuable metal elements from WPCBs.

Fully bio-based CO2-responsive pickering gel emulsions stabilized by cellulose nanocrystals combined with a rosin-based surfactant

A CO2-responsive bio-based surfactant, N-decyl-maleimidepimaric acid N, N-dimethylenediamide bicarbonate (C10MPAN+), was synthesized from rosin. C10MPAN+ showed excellent CO2-responsive properties. Novel CO2-responsive soybean oil-in-water Pickering gel emulsions were further prepared using C10MPAN+ combined with cellulose nanocrystals (CNCs). Due to the strong hydrogen bonds and electrostatic interactions, C10MPAN+ could firmly absorb on the surface of CNCs. The C10MPAN+&CNCs could form a rigid shell on the water/oil interface, resulting in the stable Pickering emulsions. Demulsification could be easily achieved upon bubbling N2 into the emulsions. The microstructure, size distribution, viscoelasticity, and stability of the Pickering emulsions were investigated using a laser particle size analyzer, an optical microscope, and rheology. Emulsions prepared by C10MPAN+&CNCs showed no obvious coalescence or phase separation over 3 months. Importantly, Pickering gel emulsions were formed at C10MPAN+concentration higher than 1 mM. The viscoelasticities of the emulsions were enhanced with the increase of C10MPAN+ concentration and CNCs content. In addition, after five cycles of emulsification/demulsification by alternative bubbling CO2/N2, the Pickering gel emulsions exhibited less difference on the droplets size and viscoelasticity. This work provides a fully bio-based responsive Pickering gel emulsion, and promotes the exploitation and utilization of biomass resources.

A comparative study on X-ray peak broadening analysis of mechanically alloyed Al2O3 particles dispersion strengthened Al 7017 alloy

AA7017 + x vol. % Al2O3 (x = 5, 10, 20) nanocomposites powders were synthesized by HEBM process with milling time of 0 h and 20 h. The synthesized nanocomposite powders were characterized using XRD (Bruker USA D8 Advance, Davinci) with CuKα (1.5406 Aͦ), 2θ range (30°-90°), and Scan Speed (1°/min) for examining the crystalline nature of the powder samples. The size and shape of the powder particle were identified by HR-SEM (FEI Quanta FEG 200F) with 30 KV voltage, wide magnification range (12x-105 x) and secondary electron mode, and HR-TEM (JEOL Japan, JEM-2100 Plus) with voltage (200 kV), and magnification range (below 50 nm). Powder particles were measured by laser scattering technique using zeta analyzer (Laser Particle size Analyser, M/s Microtrac),and finally, the melting point and peak shift variation of composite powder samples were analyzed using TG-DSC (Netzsch TG-DSC) with temperature range (25–1400 °C), and heating rate (10 °C/min)under argon atmosphere. Furthermore, the particle sizes evaluated from different models of diffraction analysis (Scherrer, Williamson-Hall, and size-strain plot, SSP, methods) were compared with the results from PSA, HR-SEM, and HR-TEM analyses. The obtained mechanical properties explained that 20h milled AA7017 + x vol. % Al2O3 (x = 5, 10, and 20) samples produced higher values; and the properties improvement in all the samples were correlated theoretically by various strengthening mechanisms.

Evaporation and micro-explosion performances of nano-fuel droplets

To investigate the effect of nanoparticles on the evaporation evolution of nano-fuels and reveal the mechanism of heterogeneous heat and mass transfer induced by the dispersion of nanoparticles, carbon nanotubes and CeO2 nano-fuels with different mass concentrations and particle sizes were prepared based on the two-step method and inspected using a laser particle size analyzer. An evaporation visualization apparatus for a single suspended droplet and an image processing technology were utilized to study the evaporation of diesel and nano-fuels at 400 and 700 °C. At 400 °C, the evaporation of diesel and nano-fuel droplets accorded with the D2-law and can be categorized as constant-volume and quasi-steady evaporation stages. The addition of nanoparticles suppressed the evaporation of fuel droplet and increasing the mass concentration or particle size can intensify the extent of suppression. At 700 °C, however, the micro-explosion of droplets occurred, and the variation in the droplet diameter did not conform with the D2-law. Evaporation can be categorized into the constant-volume and fluctuating evaporation stages. Nanoparticles, as heterogeneous nucleation sites, enhanced the expansion and micro-explosion intensities, thereby promoting the fuel droplet evaporation. An increase in the mass concentration or a decrease in the particle size can promote evaporation significantly.

A simple method for preparing ThO2 ceramics with high density

AbstractA simple and effective method for preparing ThO2 ceramics with high density has been proposed. It mainly includes a positive precipitation approach and a conventional sintering process. The SEM images and laser particle size analysis show that the prepared powder exhibits a round‐plated shape with a uniform and narrow particle size distribution, which is the key to the densification sintering of ThO2 ceramics. The XRD analyses confirm that the ThO2 ceramics sintered at 1590°C were composed of cubic fluorite phase. The effect of sintering temperature on the density of ThO2 ceramics was also investigated, and a relative density higher than 95% were achieved after sintering at 1590°C for 6 h in an air atmosphere. Moreover, the Vickers hardness was up to 8.49 GPa, the average linear expansion coefficient within 40–800°C was low to 10.97 × 10−6/K, and the thermal conductivity and the thermal diffusivity were both higher than most of traditional ceramic materials (16.94–5.86 W/m K and 7.28–1.28 mm2/s, respectively, within the temperature range of 25–800°C). The previous great performances are closely related to its high density, which enables it to be a great candidate for nuclear fuels and other potential application fields.

Utilization of calcium carbide slag as alternative filler in asphalt mastic: Filler characteristics, rheological and adhesion properties

Calcium carbide slag (CCS), a solid waste generated from a production process of acetylene gas, is considerably growing every year. It is necessary to expand application scope of CCS to improve its consumption. Feasibility of CCS as a substitute for natural limestone (NL) fillers and asphalt mastic properties was studied in this work. Properties of CCS powder and NL powder were characterized by laser particle size analyzer, scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), and acid-base analyses. Asphalt mastic characteristics were evaluated using a viscosity test, rheological test, and adhesion test. The results show that CCS has a greater particle size than NL, yet the CCS surface is rougher, which can facilitate its bonding with asphalt. In addition, high relative intensity of calcium in CCS provides excellent conditions for application as filler. Viscosity, complex modulus (|G*|), rutting factor (|G*|/sin δ), recovery percentage (R), and bonding strength can be enhanced with an increase in CCS content. While phase angle (δ) and non-recoverable creep compliance (Jnr) decrease, indicating CCS enhanced the stiffness and elastic behavior of asphalt mastic. CCS can improve rheological properties of asphalt mastic and mastic-aggregate interface adhesion, decrease moisture sensitivity and costs of asphalt mixtures. Therefore, CCS has promising applications in asphalt pavement engineering as a substitute for NL, which contributes to environmental protection.

Condensed Combustion Products Characteristics of HTPB/AP/Al Propellants under Solid Rocket Motor Conditions

Condensed combustion products (CCPs) generated during the combustion of aluminized propellants can reflect invaluable information about the combustion mechanisms of propellants. CCPs of hydroxyl-terminated polybutadiene/ammonium perchlorate/aluminum (HTPB/AP/Al) propellants were collected using an experimental apparatus capable of controlling pressure fluctuations within 0.3 MPa, and their microscopic morphologies, particle size distributions, and chemical compositions were characterized using a scanning electron microscope (SEM), laser particle size analyzer, energy disperse spectroscopy (EDS), X-ray diffraction (XRD) and complexometric titration. The results showed that the size of CCPs presented a bimodal distribution, with modes at ~5 µm and ~100 µm; particles less than 2 µm were spherical, with smooth surfaces. The main components of CCPs were C, AlN, AlCl3, Al2O3, Fe2O3 and Al, with Al2O3 being the most abundant. The combustion efficiency of aluminum increased by 3.27% when the size of virgin aluminum particles decreased from 23 µm to 13 µm, but the content of catocene (a burning-rate catalyst) and fine AP (1 µm) had little effect on combustion efficiency. Higher combustion efficiencies and smaller agglomeration sizes can be achieved at higher pressures, due to the positive correlation between pressure and the driving forces for aluminum particles exciting the burning surface.

Precipitation process for combined impurity removal from a magnesium sulphate-based leachate of ionic rare earth ore

Impurity metal ions in ionic rare earth ores are similar to rare earth ions in terms of occurrences and similarities in properties. During the leaching operation, a large number of impurity ions enter the rare earth leaching solution, which makes the crystal form of the rare earth unstable or forms an amorphous flocculent precipitate. The commonly used ammonium bicarbonate (NH4HCO3) precipitation crystallization process has low rare earth precipitation rate, long precipitation crystallization period, and high ammonia nitrogen content in precipitation wastewater. In this paper, the leaching solution obtained by ionic rare earth ore magnesium salt leaching-combined impurity removal process was taken as the research object, and the effects of precipitants, such as NH4HCO3, calcium oxide, sodium carbonate, and oxalic acid, on the preparation of crystalline rare earth precipitation were investigated through comparison. On the premise of determining the best rare earth precipitant, the effects of dosage, stirring speed, stirring time, and aging time on the preparation of crystalline rare earth precipitate were investigated further. The precipitation effects of different precipitation processes were studied systematically combined with SEM-EDS, laser particle size analysis, and other means to characterize the morphology of crystalline products. Results showed that when calcium oxide was used as a precipitant, the molar ratio was 2.5. After stirring at a constant speed of 200 r/min for 4 h and aging for 4 h, precipitates with good crystal appearance, smooth crystal surface and easy filtration were obtained. This process promoted crystal growth of rare earth precipitates, and the crystal grain size, which was beneficial to the improvement of the quality of rare earth products, increases significantly.

Multi-Mixed Metal Hydroxide as a Strong Stratigraphic Nanoclay Inhibitor in Solid-Free Drilling Fluid.

Solid-free drilling fluid has more advantages as a new type of drilling fluid compared with traditional drilling fluid, such as improving drilling efficiency, protecting oil and not having clay particles clog the oil and gas layer. In this study, Zn/Cu/Fe-doped magnesium-aluminum hydroxide (Mg-Al MMH) was prepared using the co-precipitation method and evaluated in solid-free drilling fluid. The inhibition mechanism of synthesized hydroxide was analyzed by X-ray diffraction, laser particle-size analysis and thermogravimetric analysis. The samples were directly used as drilling fluid base muds for performance evaluation. The results showed that the linear expansion rate of 4% M6-Fe was only 12.32% at room temperature within 2 h, that the linear expansion rate was 20.28% at 90 °C and that the anti-swelling rate was 81.16% at room temperature, indicating that it has a strong inhibition ability at both room temperature and at high temperatures. Meanwhile, the possibility of multi-mixed metal hydroxide as a drilling fluid base mud is discussed in this study. We found that 4% M6-Fe exhibited low viscosity, a high YP/PV ratio and high temperature resistance, and its apparent viscosity retention rate reached 100% rolled at 200 °C for 16 h, with a YP/PV ratio of 2.33.

Effectiveness of coal mine dust control: A new technique for preparation and efficacy of self-adaptive microcapsule suppressant

This study aims to make full use of the agricultural waste peanut shells to lower material costs and achieve cleaner production at the same time. Cellulose nanofibrils (CNF) extracted from peanut shells were mixed with acrylic acid (AA) and dimethyl diallyl ammonium chloride (DMDAAC) to prepare a new type of capsule core (dust suppressant). Then, the self-adaptive AA-DM-CNF/CA microcapsules were prepared under the action of calcium alginate. The infrared spectroscopy and X-ray diffraction analysis results suggest that AA, DMDAAC and CNF have experienced graft copolymerization which leads to the formation of an amorphous structure. The scanning electron microscopy analysis results demonstrate that the internal dust suppressant can expand and break the wall after absorbing water, featuring a self-adaptive function. Meanwhile, the laser particle size analysis results show that the microcapsules, inside which the encapsulated dust suppressant can be observed clearly, maintain a good shape. The product performance experimental results reveal that the capsule core and the capsule wall achieve synergistic dust suppression, thus lengthening the dust suppression time. The product boasts good dust suppression, weather resistance, degradation and synergistic combustion performances. Moreover, this study, as the first report on the development and analysis of dust-suppressing microcapsules, fills in the research gap on the reaction mechanism between dust-suppressing microcapsules and coal by MS simulation. The proposed AA-DM-CNF/CA dust-suppressing microcapsules can effectively lower the dust concentration in the space and protect the physical and mental health of coal workers. In general, this research provides a new insight into the structure control and performance enhancement of dust suppressants. Expanding the application range of microcapsules is of crucial economic and social benefits.

Preparation of microcapsules with IPDI monomer and isocyanate prepolymer as self-healing agent and their application in self-healing materials

Microcapsules were synthesized with the hybrid of Isophorone diisocyanate (IPDI) and terminal isocyanate prepolymer (CPU) as active healing agent, then the microcapsules were mixed with epoxy resin in order to form a metal anti-corrosion coating with excellent self-healing properties. Through process optimization and molecular design, the core material which was isocyanate hybrid (CPU-IPDI) with 17% Isocyanate group (-NCO) was synthesized by the reaction of IPDI and castor oil, and then the CPU-IPDI was encapsulated in the microcapsule with Diphenylmethane diisocyanate (MDI) as the shell by interface polymerization. Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric spectroscopy (TGA) confirmed the successful encapsulation of CPU-IPDI. The effect of the content of sodium lignosulfonate (NaLS) on the size and morphology of microcapsules were investigated. Optical microscopy (OM) and laser particle size analyzer show that the size of microcapsules decreases with the increase of the content of stabilizing agent. The microcapsules were prepared with 1% NaLS with a core content of 51.3%, an average particle size of 26.3 μm and a shell thickness of 1.44 ± 0.9 μm. In addition, the microcapsules loaded with CPU-IPDI were added to the epoxy coating, and the healing process of blank coating and self-healing coating was detected by SEM. The results show that the coating wound of containing 10% microcapsules has obvious healing. With saline infiltration and electrochemical impedance spectroscopy (EIS) test coating corrosion process, the results prove that after soaking in 3.5% NaCl solution for 7 days, the |Z| f = 0.01Hz value of the coating with 10 wt % microcapsules is about 1.9 × 106 Ω cm2, nearly three order higher than that of pure epoxy coating (3.1 × 103 Ω cm2), demonstrating the enhancement of protection ability.

Study on the preparation and properties of CaCO3 ultrafine powder derived from waste eggshell

In this study, eggshell-derived CaCO3 ultrafine powder was prepared from waste eggshell with the method of omnidirectional planetary ball mill. The particle size distribution was measured by laser particle size analyzer. Then, the parameters of grinding kinetic equation of eggshell powder were obtained by software fitting, and the grinding model and characteristic equation of particle-size distribution of the eggshell-derived CaCO3 powder were discussed. The results showed that the best grinding conditions were as follows: using 3 mm zirconia grinding ball, 400 rpm, 50% filling rate, 50% slurry concentration, and ball-milling time of 30 min. The grinding kinetic equation can well simulate the eggshell crushing process. The equation showed that with the prolongation of milling time, the large particle size of the eggshell powder gradually decreased, and the milling efficiency was 0 after 60 min. The Rosin–Rammler–Bennet distribution model could be used to describe the distribution characteristics of the cumulative particle size of the eggshell powder, and the fitting degree of particle size distribution at each milling time could reach R2 > 0.99. No chemical change occurred in the eggshell powder before and after grinding. However, the calcite crystal structure of eggshell-derived CaCO3 ultrafine powder becomes incomplete.

ОБОСНОВАНИЕ ФИЗИКО-ХИМИЧЕСКИХ ПАРАМЕТРОВ СУБСТАНЦИЙ РУТИНА И ГЕСПЕРИДИНА ДЛЯ СОЗДАНИЯ ДИСПЕРГИРУЕМЫХ ТАБЛЕТОК

According to the data provided by the World Health Organization, disorders in the functioning of the cardiovascular system lead to disappointing consequences. A third of deaths worldwide occur in this category of diseases. In this regard, the urgency of developing and creating medicines for the prevention and treatment of cardiovascular diseases, including chronic venous insufficiency, is increasing. As active substances, we selected insoluble forms of hesperidin and rutin. One of the main properties of water-insoluble substances used for the preparation of dispersible tablets is the degree of dispersion of medicinal substances. As a consequence, the aim of the work was to study the physico-chemical characteristics of rutin and hesperidin, which are necessary to ensure optimal biopharmaceutical properties of dispersed tablets. The following materials were used during the work: substances of rutin and hesperidin, a PE-5300V spectrophotometer, a laser particle size analyzer ANALYSETTE 22 NanoTec, a microscope "Micromed-1" with a trinocular nozzle and a digital camera HA2307 HDMI industrial camera (14MP). According to the results of the conducted studies, the average particle size for the substances rutin and hesperidin was established, which amounted to 17 microns and 2.6 microns, respectively. Micrographs of the studied substances of rutin and hesperidin were made using a microscope with a trinocular nozzle, and their visual examination was also carried out. In accordance with the results of microscopy, it can be noted that the substance rutin requires additional grinding in order to improve the biopharmaceutical properties of the dispersible tablets. While, the substance of hesperidin has sufficient dispersion to obtain the developed dosage form.