Continuous Phase Research Articles

Sensitive Determination of Quercetin in food Samples implementing Magnetic Dispersive Solid Phase Extraction coupled with Ion Mobility Spectrometry

Quercetin (QUR) is a vital flavonoid, which is found in dietary human. The quick analysis of QUR is difficult on account of utilizing complicated methods. Hence, we developed a proposed method based on ion mobility spectrometry (IMS) to evaluate the fast analysis of QUR in food samples. This analytical method combined the benefit of polypyrrole-coated magnetic dispersive solid phase extraction (MDSPE) as a sorbent phase for the QUR extraction, and also the strength of IMS for the rapid detection. Nanoparticle (NP) characterization was investigated through VSM, FT-IR, XRD, BET, and as well as FE-SEM analysis. Sample pH, amount of nanoparticles, type and volume of desorption solvent, extraction time, and desorption time as impressive parameters in MDSPE method were investigated and optimized. The calibration curve was linear in the range of 1.0-90.0ngmL-1, with a determination coefficient (R2) of 0.9954. The limit of detection (LOD) and the limit of quantification (LOQ) for QUR were 0.31 and 1.02ngmL-1, respectively. The RSD% of QUR through seven parallel analyses was 4.44. This analytical work was executed to quantify QUR in honey and tea samples without any derivation procedure needed. The recovery values for QUR were estimated in the range of 92.5% to 96.7% using the proposed method. Also, according to the attained results from HPLC analyses, the applicability, and susceptibility of the current method was verified.

Fe3O4@PS-DVB microspheres modified with urea functional groups for rapid and green extraction of fluorinated aromatic carboxylic acids from tap and formation water

The present study describes the trace analysis of 23 fluorinated aromatic carboxylic acids based on the dispersive magnetic solid phase extraction (m-SPE) technique coupled with the gas chromatography coupled with mass spectrometry (GC–MS) electron ionization (EI) technique. A commercial hydrophilic-lipophilic balanced (HLB) material polystyrene divinyl benzene having urea functional groups was modified with magnetite nanoparticles and employed as a sorbent for dispersive m-SPE of fluorobenzoic acids (FBAs) from the tap and formation water samples. The extraction occurred due to π- π interaction between the aromatic ring of synthesized sorbent and the aromatic ring of FBAs, the hydrogen bond formation between the urea functional group of the sorbent and carbonyl oxygen, fluorine of the FBAs. As a result, the method was precise, rapid, reproducible, and calibrated with the coefficient of variation (R2) greater than 0.98 for all 23 compounds. The instrument detection limit (IDL) and method detection limit (MDL) were found in the range of 2.60 – 8.25 ng/mL and 0.08 – 0.28 ng/mL respectively. Extraction efficiencies were found in the range of 83.80–100 % for tap water samples and 78.41–98.92 % for formation water samples, respectively, with an enrichment factor of 33.33–66.66 and a maximum RSD of 7.07 %. The recyclability and magnetic properties of the synthesized material were also investigated, resulting in the material being reused for six cycles without impacting its performance; hence, the method offers rapid determination and high throughput analysis of FBAs. In addition, simulation studies were performed using the adsorption location tool of Material Studio, confirming the interaction sites of sorbent with FBAs. AGREE evaluated the analytical greenness of the method, and the score was found to be 0.51.

Effect of different homogenization times on the mechanical properties of 7075 aluminum alloy

The effects of homogenization temperature at 465 °C and different homogenization times (6h/12h/24h/36/h/48h) on the microstructure and mechanical properties of as-cast 7075 aluminum alloy were studied using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM), hardness testing, and tensile testing. The results show that during the initial stage of homogenization, the continuous bright white network of σ-Mg (Zn, Cu, Al)2 phase transforms into a white broken flocculent S–Al2CuMg phase with the dissolution of Zn. In the middle stage, the S–Al2CuMg phase dissolves and Cu diffuses into primary Al7Cu2Fe, accompanied by precipitation of a large amount of dispersed nanoscale MgZn2 phase. With the homogenization time, the Al7Cu2Fe and MgZn2 phase are coarsened. The strength and plasticity of the alloy show a trend of first increase and then decrease. When the homogenization time is 24 h, the ultimate tensile strength (UTS), yield strength (YS), and elongation reach the peak values of 231.1 MPa, 134.2 MPa, and 4.0%, respectively. The phase transformation and dissolution mechanism during the homogenization process of 7075 aluminum alloy provides a scientific theoretical basis for improving the mechanical properties of the alloy.

Emergence of cooperation under punishment: A reinforcement learning perspective.

Punishment is a common tactic to sustain cooperation and has been extensively studied for a long time. While most of previous game-theoretic work adopt the imitation learning framework where players imitate the strategies of those who are better off, the learning logic in the real world is often much more complex. In this work, we turn to the reinforcement learning paradigm, where individuals make their decisions based upon their experience and long-term returns. Specifically, we investigate the prisoners' dilemma game with a Q-learning algorithm, and cooperators probabilistically pose punishment on defectors in their neighborhood. Unexpectedly, we find that punishment could lead to either continuous or discontinuous cooperation phase transitions, and the nucleation process of cooperation clusters is reminiscent of the liquid-gas transition. The analysis of a Q-table reveals the evolution of the underlying "psychologic" changes, which explains the nucleation process and different levels of cooperation. The uncovered first-order phase transition indicates that great care needs to be taken when implementing the punishment compared to the continuous scenario.

In-situ nanoscale precipitation behavior and strengthening mechanism of WC/IN718 composites manufactured by laser powder bed fusion

Nickel matrix composites (NMCs) have received much attention as they show excellent high temperature performances, which could meet the demand for hot-end components in severe environments. In this study, the duplex in-situ nanoscale carbides and oxides reinforcing IN718 were fabricated by laser powder bed fusion (LPBF) and addition of submicron WC particles. The microstructural features and mechanical properties were investigated with variations of WC content (0, 0.5, 2, and 4wt.%). The columnar dendrites with strong <001> texture that boundary distributed continuous Laves phase were found in the LPBF-processed IN718. Incorporating WC led to higher laser absorption and processability, whereas it also decreased the anisotropy of the matrix featured by weak texture index. With an optimized content of 2wt.%, the WC was dissolved into W and C atoms under laser irradiation, which promoted the homogeneous precipitation of intergranular cubic (Nb, Ti)C (∼50 nm) and intragranular spherical Al2O3 (∼20 nm). These precipitates would for heterogenous nucleation to refine grains (∼12.6 μm) and bring about high-density dislocations. The yield strength (YS) and ultimate tensile strength (UTS) increased by 28.8% and 26.5%, respectively, while maintaining high elongation compared with reported NMCs, demonstrating a favorable strength-ductility combination. Finally, the mechanism of microstructure evolution and strengthening was elucidated.

Evolution of cracks in laser powder bed fused AA2024 and its processing parameter dependence

Hot cracking is one of the most hideous issues in the fabrication of high-strength aluminum alloys via laser powder bed fusion (LPBF). This study investigated the evolution of hot cracking in LPBFed AA2024 and explored its processing parameter dependence. Results showed that most cracks distribute along continuous eutectic phases residing at grain boundaries. At the last stage of solidification, the eutectic composition with low melting point exists as a liquid film, which can be easily ruptured under stress caused by thermal contraction. This leads to the formation of cracks along grain boundaries. This cracking process is also related to the misorientation angle of grains, where higher angle results in more stable liquid films. Furthermore, increasing the laser power transforms the grain structure from fine columnar grains to coarse columnar grains, which eventually transform to a mixture of columnar and equiaxed grains. This grain structure transition results in the decrease followed by increase of critical stress for the rupture of liquid film. On the other hand, decreasing the scanning speed increases the eutectic phase content, which could enhance the permeability of mushy zone and thus reduce the cracking susceptibility. These findings could provide guidance for the fabrication of crack-free high-strength aluminum alloys via LPBF.

Internal blocking and bonding to strengthen the mechanical properties and prevent collapse and leakage of fragmented coalbed methane (CBM) reservoirs by cohesive drilling fluids

Exploiting coalbed methane (CBM) not only provides clean energy but also reduces the risk of gas explosions in coal mining. CBM reservoirs have low mechanical strength due to poor continuity, strong heterogeneity, and rich natural fractures, which bring about wellbore collapse and leakage during the drilling operations of CBM wells. As for fragmented coalbed methane reservoirs, plugging the leakage channel and increasing the density of drilling fluid would result in new collapse problems and leakage. To achieve this, we developed a cohesive fuzzy ball drilling fluid (FBDF) to adhere fragmented coal particles from the discontinuous phase to the continuous phase and strengthen their mechanical properties to prevent collapse and leakage. The microcosmic interaction of coal seams with different fluid systems and adhesive properties have been comprehensively evaluated. The mechanical parameters of coal plugs treated with common potassium chloride drilling fluid (PCDF), polymer drilling fluid (PDF), and FBDF were carefully compared through uniaxial and triaxial experiments. Additionally, the adhesive mechanism of FBDF to coal fines was comprehensively discussed. The results showed that the FBDF would form an elastic mesh structure through hydrophobic association, and bond the small particles of coal debris together to form a stable structure similar to "steel bar-concrete" "macromolecule-particle". The viscous force on the surface of coal rocks treated by FBDF was higher than that of coal plungers treated by PCDF or PDF. The uniaxial compressive strength of core samples treated by FBDF was increased by 47.1%, while the modulus of elasticity, Poisson's ratio, and brittleness coefficient were decreased by 19.94%, 11.95%, and 4%, respectively, compared to dry coal plug. FBDF also showed preferential plugging and permeability recovery abilities. The FBDF fluids have been successfully applied in two CBM wells characterized by "top leakage and bottom collapse", neither collapse nor leakage occurred during the drilling process. It provided a new internal blocking and bonding technology for fragmented reservoirs.

Generation of parabolic beam using an amplitude and phase modulated metasurface

In this work, non-diffraction parabolic beam is generated using a double-layer transmission metasurface in the microwave frequency range. A transmissive unit cell with bilayered substrates and three metallic layers is designed. By controlling the orientation angle and the opening angle of the intermediate ∈-shaped metallic layer, transmission amplitude from 0 to 1 and continuous phase shift from 0° to 360° can be modulated simultaneously. To experimentally verify the proposed concept and design, a transmissive metasurface is fabricated and measured at 20 GHz. The simulated and measured results are in good agreement with the theoretical results, and prove the generated parabolic beam still maintained non-diffraction and self-healing characteristics within the maximum non-diffraction distance of 40λ. The generated microwave parabolic beam with its properties can be applied to improving the distance and efficiency of WPT and near field modulation of complex EM waves.

Generalized anxiety disorder screening scores are associated with greater treatment need among Veterans with depression

Comorbid anxiety and depression predict a poorer prognosis than either disorder occurring alone. It is unclear whether self-reported anxiety symptom scores identify patients with depression in need of more intensive mental health services. This study evaluated how anxiety symptoms predicted treatment receipt and outcomes among patients with new depression diagnoses in the Veterans Health Administration (VHA). Electronic medical record data from 128,917 VHA patients (71.6% assessed for anxiety, n = 92,237) with new diagnoses of depression were analyzed to examine how Generalized Anxiety Disorder-7 (GAD-7) scores predicted psychotropic medication prescriptions, psychotherapy receipt, acute care service utilization, and follow-up depression symptoms. Patients who reported severe symptoms of anxiety were significantly more likely to receive adequate acute phase and continuation phase antidepressant treatment, daytime anxiolytics/sedatives, nighttime sedative/hypnotics, and endorse more severe depression symptoms and suicidal ideation at follow-up. Patients who reported severe symptoms of anxiety at baseline were less likely to initiate psychotherapy. The GAD-7 may help identify depressed patients who have more severe disease burden and require additional mental health services.

The coupled dynamics of information-behavior-epidemic propagation considering the heterogeneity of adoption thresholds and network structures in multiplex networks

During epidemics, individual responses to prevention and control information vary significantly, affecting the execution of preventive measures. This paper introduces a novel model to analyze the co-evolution of the information-behavior-epidemic dynamic, accounting for the heterogeneity in individual behavioral adoption thresholds and network structures. The model consists of three layers: the upper layer, utilizing scale-free social networks to represent the diffusion of information; the middle and lower layers, employing community networks, to illustrate individuals’ decision-making and epidemic transmission processes, respectively. We applied the Heaviside step function to depict the effects of information and local environmental factors on individuals’ decisions. Through the microscopic Markov chain approach (MMCA), we determined the epidemic threshold. Our methodology also included extensive Monte Carlo (MC) simulations to validate our theoretical predictions. Our results reveal several key insights: (i) reducing community mobility and the threshold for adopting preventive behaviors can significantly restrain the scale of the epidemic and delay outbreaks; (ii) the level of individual activity in the physical contact network has a significant influence on epidemic transmission; (iii) integrating individuals’ behavior adoption thresholds induces a two-stage phase change, deviating from the continuous phase transition typically observed in epidemic transmission.

Development of Cellulose Microfibers from Mixed Solutions of PAN-Cellulose in N-Methylmorpholine-N-Oxide.

Mixed solutions of PAN with cellulose in N-methylmorpholine-N-oxide (NMMO) were prepared. Systems with a fraction of a dispersed phase of a cellulose solution in NMMO up to 40% are characterized by the formation of fibrillar morphology. The fibrils created as the mixed solution is forced through the capillary take on a more regular order as the cellulose content in the system drops. The systems' morphology is considered to range from a heterogeneous two-phase solution to regular fibrils. The generated morphology, in which the cellulose fibrils are encircled by the PAN, can be fixed by spinning fibers. Cellulose fibrils have a diameter of no more than a few microns. The length of the fibrils is limited by the size of the fiber being formed. The process of selectively removing PAN was used to isolate the cellulose microfibrils. Several techniques were used to evaluate the mechanical properties of isolated cellulose microfibers. Atomic force microscopy allowed for the evaluation of the fiber stiffness and the creation of topographic maps of the fibers. Cellulose microfibers have a higher Young's modulus (more than 30 GPa) than cellulose fibers formed in a comparable method, which affects the mechanical properties of composite fibers.

Phase Transition to Turbulence via Moving Fronts.

Directed percolation (DP), a universality class of continuous phase transitions, has recently been established as a possible route to turbulence in subcritical wall-bounded flows. In canonical straight pipe or planar flows, the transition occurs via discrete large-scale turbulent structures, known as puffs in pipe flow or bands in planar flows, which either self-replicate or laminarize. However, these processes might not be universal to all subcritical shear flows. Here, we design a numerical experiment that eliminates discrete structures in plane Couette flow and show that it follows a different, simpler transition scenario: turbulence proliferates via expanding fronts and decays via spontaneous creation of laminar zones. We map this phase transition onto a stochastic one-variable system. The level of turbulent fluctuations dictates whether moving-front transition is discontinuous, or continuous and within the DP universality class, with profound implications for other hydrodynamic systems.

Into the Void: Single Nanopore in Colloidally Synthesized Bi2Te3 Nanoplates with Ultralow Lattice Thermal Conductivity.

Bi2Te3 is a well-known thermoelectric material that was first investigated in the 1960s, optimized over decades, and is now one of the highest performing room-temperature thermoelectric materials to-date. Herein, we report on the colloidal synthesis, growth mechanism, and thermoelectric properties of Bi2Te3 nanoplates with a single nanopore in the center. Analysis of the reaction products during the colloidal synthesis reveals that the reaction progresses via a two-step nucleation and epitaxial growth: first of elemental Te nanorods and then the binary Bi2Te3 nanoplate growth. The rates of epitaxial growth can be controlled during the reaction, thus allowing the formation of a single nanopore in the center of the Bi2Te3 nanoplates. The size of the nanopore can be controlled by changing the pH of the reaction solution, where larger pores with diameter of ∼50 nm are formed at higher pH and smaller pores with diameter of ∼16 nm are formed at lower pH. We propose that the formation of the single nanopore is mediated by the Kirkendall effect and thus the reaction conditions allow for the selective control over pore size. Nanoplates have well-defined hexagonal facets as seen in the scanning and transmission electron microscopy images. The single nanopores have a thin amorphous layer at the edge, revealed by transmission electron microscopy. Thermoelectric properties of the pristine and single-nanopore Bi2Te3 nanoplates were measured in the parallel and perpendicular directions. These properties reveal strong anisotropy with a significant reduction to thermal conductivity and increased electrical resistivity in the perpendicular direction due to the higher number of nanoplate and nanopore interfaces. Furthermore, Bi2Te3 nanoplates with a single nanopore exhibit ultralow lattice thermal conductivity values, reaching ∼0.21 Wm-1K-1 in the perpendicular direction. The lattice thermal conductivity was found to be systematically lowered with pore size, allowing for the realization of a thermoelectric figure of merit, zT of 0.75 at 425 K for the largest pore size.

Total ankle arthroplasty improves discrete and continuous stance phase gait symmetry

BackgroundTotal ankle arthroplasty (TAA) is used to treat symptomatic end-stage ankle arthritis (AA). However, little is known about TAA's effects on gait symmetry. Research questionDetermine if symmetry changes from before surgery through two years following TAA utilizing the normalized symmetry index (NSI) and statistical parametric mapping (SPM). Methods141 patients with end-stage unilateral AA were evaluated from a previously collected prospective database, where each participant was tested within two weeks of surgery (Pre-Op), one year and two years following TAA. Walking speed, hip extension angle and moment, hip flexion angle, ankle plantarflexion angle and moment, ankle dorsiflexion angle, weight acceptance (GRF1), and propulsive (GRF2) vertical ground reaction forces were calculated for each limb. Gait symmetry was assessed using the NSI. A linear mixed effects model with a single response for each gait symmetry variable was used to examine the fixed effect of follow-up time (Pre-Op, Post-1 yr, Post-2 yr) and the random effect of participant with gait speed as a covariate in the model. A one-dimensional repeated measures analysis of variance (ANOVA) statistical parameter mapping (SPM) was completed to examine differences in the time-series NSI to determine regions of significant differences between follow-up times. ResultsRelative to Pre-Op values, GRF1, and GRF2 showed increased symmetry for discrete metrics and the time-series NSI across sessions. Hip extension moment had the largest symmetry improvement. Ankle plantarflexion angle was different between Pre-Op and Post-2 yr (p=0.010); and plantarflexion moment was different between Pre- Op and each post-operative session (p<0.001). The time-series Ankle Angle NSI was greater during the early stance phase in the Pre-Op session compared to Post-2 yr. SignificanceSymmetry across most of the stance phase improved following TAA indicating that TAA successfully improves gait symmetry and future work should determine if these improvements restore symmetry to levels equivalent with health age-match controls.

TO HIGHLY PRODUCTIVE SYNTHESIS OF ALUMINUM NANOPARTICLES IN PLASMA FLOW AT ATMOSPHERIC PRESSURE

Purpose. To study the highly productive evaporation of aluminum micron powder in an atmospheric pressure plasma jet for the synthesis of nanoaluminum. Using special plasma technology, nanoparticles can be produced by rapid melting and evaporation of the initial micrometer particles and their subsequent re-nucleation. Research methods. Methods of mathematical and computer modeling of subsonic plasma turbulent jets at atmospheric pressure and experimental studies of two-phase processes during thermal plasma treatment using an arc plasma torch. Results. Based on computer modeling, a special reactor system was designed and developed, which includes a plasma-jet reactor with an electric arc plasma torch for the synthesis of aluminum nanoparticles. Numerical modeling makes it possible to determine the position of the melting point, evaporation and crushing of a molten particle, the evolution of the fractional composition of the dispersed phase, and find the speed and temperature of the particle in the area from its melting point to the crushing point. An experimental test of the operation of the reactor system was carried out using arc plasma torches with a power of 30 and 150 kW. It has been shown that intensifying the fragmentation of dispersed raw materials in a plasma jet can be useful in technologies for producing nanomaterials. The consequence of the fragmentation process is the redistribution of the fractional composition of the powder along the plasma jet and the accompanying changes in the dynamics of movement, heating and evaporation of particles. It has been determined that when the temperature of the largest aluminum particles reaches 2500 C, the total amount of evaporated mass is theoretically equal to 100%. The main parameters influencing the behavior of particles in a plasma jet are particle diameter, powder injection rate, flow rate, temperature and composition of the plasma gas. Taking these parameters into account will allow the process to operate at increased productivity. Scientific novelty. A mathematical description of the process of fragmentation a polydisperse powder, based on a continuum approach, has been obtained, which makes it possible to determine the position of the crushing point of a molten particle, the fractional composition of the dispersed phase, and find the speed and temperature of the particle in the area from its melting point to the point of crushing and evaporation. It was shown for the first time that it is possible to carry out a process in which complete evaporation of a molten drop is achieved due to the high enthalpy of the plasma before the end of mixing with steam. Practical value. A special reactor system has been designed and developed, which includes a plasma-jet reactor with an electric arc plasmatron for the synthesis of aluminum nanoparticles. The operating parameters of the reactor system have been determined, which will allow the synthesis of aluminum nanoparticles to be carried out with high productivity.

Development of a Dispersive Liquid-Liquid Aerosol Phase Extraction Method for the Quantification of Ag, Cd, Cu, Ni, and Pb in Seawater by Inductively Coupled Plasma Optical Emission Spectroscopy.

The dispersive liquid-liquid aerosol phase extraction (DLLAPE) method was applied for the determination of Ag, Cd, Cu, Ni, and Pb in seawater samples by inductively coupled plasma optical emission spectroscopy (ICP-OES). Key parameters such as sample pH and extractant concentration were systematically evaluated, with ammonium O,O'-diethyldithiophosphate (DDTP) identified as the optimal chelating agent. Optimal extraction conditions were achieved at pH 2.5 for Ag, Cu, Ni, and Pb, while Cd extraction efficiency was found to be pH independent. The extractant concentration did not greatly improve the extraction efficiency. Furthermore, the influence of nebulizer gas flow rate and extraction time was evaluated, achieving the maximum extraction yield at 0.6 L min-1 and 120 s, respectively. The method was evaluated for accuracy and bias through recovery studies, and the results showed that most elements had recovery rates close to 100% with relative standard deviation values in between 3 and 9%. However, in the case of Ag and Ni, 1.184 and 1.089 correction factors were, respectively, applied to compensate for the bias. Moreover, the procedural limits of quantification (pLOQs) found for Ag, Cd, Cu, Ni, and Pb were 0.4, 0.14, 0.2, 0.2, and 0.2 μg L-1, respectively. The in-house validation of the method provided expanded uncertainty values lower than 6% for all elements except for Ag (16.6%). Finally, the application of the method to real seawater samples from coastal areas in Alicante and San Juan (Spain) confirmed its suitability for trace metal analysis in complex marine matrices, underscoring its potential for environmental monitoring and research.

Fabrication of crosslinked starch microspheres via water-in-water Pickering emulsion and their application in controlled release of Vitamin C

Green technology for the fabrication of bio-degradable microspheres is exciting and needed. In this study, a new water-in-water Pickering emulsion green technology is proposed for the fabrication of the crosslinked starch microspheres with sodium tripolyphosphate as the crosslinker, polyethylene glycol aqueous solution as the continuous phase (PEG phase) and starch aqueous solution as the dispersed phase (starch phase). The factors that affect the morphology and particle sizes of cross-linked starch microspheres are investigated by laser scanning confocal microscope (LCM) and laser particle size analyzer. The results reveal that the particle sizes of crosslinked starch microspheres are increasing with increased starch concentration. The particle sizes of crosslinked starch microspheres show a first increase and then decrease trend with the increase of the concentration of PEG 20,000 in the PEG phase. The hydrophobic nano silica is used as an emulsifier to form water-in-water Pickering emulsion and shows an obvious effect on the morphology of starch microspheres. When the starch concentration is 20.00 wt%, PEG 20000 concentration is 32.56 wt%, the ratio of starch to PEG phase is 0.20 and the amount of silica is 5.00 wt% of starch, starch microspheres with regular shapes are obtained with the size of about 32.30 ± 0.22 µm. The fabricated cross-linked starch microspheres are non-crystalline and show good water and oil absorption performances. The application of fabricated crosslinked starch microspheres in the adsorption and release of Vitamin C is conducted. The maximum adsorption capacity of crosslinked starch microspheres for Vitamin C reaches 309.9 mg/g. Starch microspheres show a controlled release of Vitamin C in water. This study indicated that crosslinked starch microspheres can be fabricated through a green water-in-water Pickering emulsion technology and may find potential applications in degradable controlled-release microspheres.

Preparation of μ-HMX/C-Based Composite Energy Composite Microspheres by Microdroplet Technology.

Taking μ-HMX particles as the main research subject, a set of microdroplet sphericalization coating technology platforms was designed and constructed to realize the preparation of composite microspheres by sphericalization coating of μ-HMX. The suspension stability of μ-HMX particles and the mechanism of droplet formation were investigated, and the application effect of nanocarbon materials was also analyzed. The results showed that the prepared sample microspheres all showed a better spherical morphology, as well as good dispersibility; the samples with micron-sized particles for spherical coating had a lower thermal decomposition temperature, a higher energy release efficiency, lower mechanical sensibility, and better combustion performance; the incorporation of CNFs changed the combustion mode of the system, which resulted in the microsphere system of μ-HMX having a good safety performance. The stability and feasibility of uniform spheronization when the dispersed phase is a low-concentration particle suspension system in the spheronization encapsulation process by microdroplet technology were verified.

Acoustic radiation force-induced longitudinal shear wave for ultrasound-based viscoelastic evaluation

Acoustic radiation force (ARF) is widely used to induce shear waves for evaluating the mechanical properties of biological tissues. Two shear waves can be generated when exciting with ARF: a transverse shear wave, also simply called shear wave (SW), and a longitudinal shear wave (LSW). Shear waves (SWs) have been broadly used to assess the mechanical properties. Some articles have reported that the LSW can be used to evaluate mechanical properties locally. However, existing LSW studies are mainly focused on the group velocity evaluation using optical coherence tomography (OCT). Here, we report that a LSW generated with ARF can be used to probe viscoelastic properties, including shear modulus and viscosity, using ultrasound. We took advantage of the surface boundary effect to reflect the LSW, named RLSW, to address the energy deficiency of LSW induced by ARF. We systematically evaluated the experiments with tissue-mimicking viscoelastic phantoms and validated by numerical simulations. Phase velocity and dispersion comparison between the results induced by a RLSW and a SW exhibit good agreement in both the numerical simulations and experimental results. The Kelvin-Voigt (KV) model was used to determine the shear modulus and viscosity. RLSW shows great potential to evaluate localized viscoelastic properties, which could benefit various biomedical applications such as evaluating the viscoelasticity of heterogeneous materials or microscopic lesions of tissues.

Properties of Ni-B/B Composite Coatings Produced by the Electroless Method under Semi-Technical Line Conditions

Composite coatings have been successfully fabricated at the laboratory scale in many research centers around the world; however, it is still a major challenge to transfer the positive results of the work to the industrial scale. This paper presents the technology for the production of Ni-B and Ni-B/B composite coatings on a pilot experimental semi-technical line by chemical reduction. A process scheme for the fabrication of Ni-B layers and composite coatings with a nickel–boron matrix and a dispersive phase in the form of boron nanoparticles was developed. All stages of the fabrication process were described in detail. The dispersion phase of the boron particles was characterized, and the performance properties of the Ni-B and Ni-B/B composite coatings produced on a pilot electroplating line were studied. The structure and morphology of the Ni-B/B composite coatings were characterized for comparison with nickel–boron coatings. Their mechanical and tribological properties and adhesion to the substrate were studied. The influence of the dispersion phase of boron particles on the structure and functional properties of the composite coatings was evaluated. In order to improve the performance of the fabricated coatings, a heating process at 400 °C was carried out, and the performance of Ni-B and composite Ni-B/B coatings was studied after the heat treatment operation.