Dual Particle Research Articles

Smart Mn7+ Sensing via Quenching on Dual Fluorescence of Eu3+ Complex-Modified TiO2 Nanoparticles.

In this work, titania (TiO2) nanoparticles modified by Eu(TTA)3Phen complexes (ETP) were prepared by a simple solvothermal method developing a fluorescence Mn7+ pollutant sensing system. The characterization results indicate that the ETP cause structural deformation and redshifts of the UV-visible light absorptions of host TiO2 nanoparticles. The ETP also reduce the crystallinity and crystallite size of TiO2 nanoparticles. Compared with TiO2 nanoparticles modified with Eu3+ (TiO2-Eu3+), TiO2 nanoparticles modified with ETP (TiO2-ETP) exhibit significantly stronger photoluminescence under the excitation of 394 nm. Under UV excitation, TiO2-ETP nanoparticles showed blue and red emission corresponding to TiO2 and Eu3+. In addition, as the concentration of ETP in TiO2 nanoparticles increases, the PL intensity at 612 nm also increases. When ETP-modified TiO2 nanoparticles are added to an aqueous solution containing Mn7+, the fluorescence intensity of both TiO2 and ETP decreases. The evolution of the fluorescence intensity ratio (I1/I2) of TiO2 and ETP is linearly related to the concentration of Mn7+. The sensitivity of fluorescence intensity to Mn7+ concentration enables the design of dual fluorescence ratio solid particle sensors. The method proposed here is simple, accurate, efficient, and not affected by the environmental conditions.

Effect of particle mass inhomogeneity on the two-dimensional Rayleigh–Bénard system of Yukawa liquids: A molecular dynamics study

The effect of particle mass inhomogeneity on the evolution of macroscale fluid flow in the Rayleigh–Bénard system of two-dimensional Yukawa liquids is studied using “first principles” classical molecular dynamics simulations. We find that Rayleigh–Bénard convection cells (RBCCs) formed in the quasi-steady-state become unstable at later times as a result of introducing a small fraction (≤2% of the total particles) of particle mass inhomogeneity in a Yukawa system made up of point particles of uniform charges. The unstable RBCCs, after passing through several intermediate states, give rise to a unidirectional shear flow in the direction perpendicular to the external gravity. Depending on the fraction and phase space of the particle mass inhomogeneity introduced in the system, the unidirectional shear flow further evolves to give shearless parallel flow. We use single or dual particle mass distributions of various forms, such as Gaussian distribution, Dirac-delta distribution, or a combination of both, around different mean values in order to introduce particle mass inhomogeneity. The role of system size on the emergence of various intermediate fluid flow states is also investigated. Furthermore, by introducing an inhomogeneity in charge commensurate with mass inhomogeneity, we demonstrate the robustness of our findings. Finally, for the case of decreasing correlation strength and for otherwise identical parameters, it is shown that the particle mass inhomogeneity fails to generate shear flows from RBCCs in 2D Yukawa liquids.

The Influence of Hydroxyapatite and Alumina Particles on the Mechanical Properties and Corrosion Behavior of Mg-Zn Hybrid Composites for Implants.

Considering the necessity for a biodegradable implant alloy with good biocompatibility and mechanical strength, dual ceramic particles of HAP and Al2O3 were added to Mg-Zn alloy to produce a new hybrid composite using powder metallurgy. The paper reports the mechanical and corrosion behaviour of Mg-Zn/HAP/Al2O3 hybrid composites containing variable wt.% HAP and Al2O3 with 15 wt.% total ceramic content. The powders of Mg, Zn, Al2O3 and HAP were milled in a high-energy ball mill, and then compacted under 400 MPa and sintered at 300 °C. Density and compression strength increased with increasing Al2O3 content. HAP facilitated weight gain in Hanks balanced salt solution due to deposition of an apatite layer which promoted anodic behaviour with higher corrosion resistance. A hybrid composite of Mg alloy with 5 wt.% Al2O3 and 10 wt.% HAP displayed 153 MPa compressive strength, 1.37 mm/year corrosion resistance and bioactivity with a CA:P ratio of 1:1.55 and appears to be the most promising biodegradable implant material tested.

Flexible inorganic–organic hybrids with dual inorganic components

Combining multiple inorganic components is an effective approach to improve the mechanical properties of inorganic–organic hybrid materials. The inorganic components can form interactions with the organic polymer matrix, and there is thus a need to understand the reinforcement mechanism under the optimal combination of organic polymer and inorganic particles. In this work, we prepared a series of dual inorganic particle–based titania/silica–poly(tetrahydrofuran)–poly(ε-caprolactone) (TiO2/SiO2–PTHF–PCL) hybrids by means of simultaneous cationic ring-opening polymerization and sol–gel reaction. In addition to constructing hybrid networks, the SiO2 and TiO2 components play important roles in multiple toughening mechanisms. The prepared dual inorganic hybrids feature enhanced thermal stability and mechanical properties when compared with the ones with a single inorganic component. The optimized mixing of such two inorganic components is identified through mechanical tests, revealing that the hybrid polymer70/(Si0.6Ti0.4)30 (70/18/12 mass ratio) has the highest compressive failure strain (80%) and compressive ultimate strength (1.3 MPa) as well as storage modulus (120 kPa), enabling elongation of up to 37% when compared with its original length. We thus find that the dual inorganic component approach is an effective strategy to enhance the mechanical properties of hybrid materials, suggesting potential applications as scaffolds for tissue engineering and soft robotics.

Weakly Acidic pH and Reduction Dual Stimuli-Responsive Gel Particles

This paper reports the facile preparation of dual stimuli-responsive gel particles that simultaneously respond to weakly acidic and reducing stimuli and the application of these gel particles as a drug delivery carrier. The dual stimuli-responsive gel particles composed of a pH-responsive polymer network cross-linked with reduction stimuli-responsive disulfide cross-links, and biocompatible poly(ethylene glycol) cross-links were prepared by soap-free emulsion polymerization. The resulting gel particles were colloidally stable at physiological ionic strength and had a diameter of approximately 200 nm with a narrow size distribution. The resulting gel particles slightly swelled in an acidic environment. On the other hand, the gel particles drastically swelled under simultaneous weakly acidic and reducing conditions because of the ionization of tertiary amino groups in the gel network and a decrease in the cross-linking density resulting from cleavage of the disulfide cross-links. When cells were treated with the gel particles, they were taken up by cells via the endocytosis pathway and distributed in the cytosol after endosomal escape by the proton sponge effect. In addition, a hydrophobic drug, doxorubicin (Dox), was loaded into the gel particles through hydrophobic interactions. Dox was released from the gel particles under weakly acidic and reducing conditions, while the Dox release was inhibited at neutral pH. The weakly acidic pH- and reduction stimuli-responsive release of Dox from gel particles was attributed to the drastic swelling of these particles. The fascinating properties of the dual stimuli-responsive gel particles suggest that they can provide a useful platform for designing intracellular drug delivery carriers.

Novel co‐estimation strategy based on forgetting factor dual particle filter algorithm for the state of charge and state of health of the lithium‐ion battery

For the battery management system, accurate estimation of the state of charge and state of health is of great significance. Herein, the ternary Li-ion battery is taken as the research object; the second-order resistor-capacitor (RC) equivalent circuit is taken advantage of to characterize the battery performance. A method for calculating the state of health of Li-ion batteries based on capacity fading was established. A novel forgetting factor dual particle filter algorithm is proposed for co-estimation of the state of charge and state of health by combining the forgetting factor and the particle filter algorithm. The state of charge and state of health of Li-ion batteries under Beijing Bus Dynamic Stress Test conditions are evaluated. In the state of charge estimation, the maximum error, mean absolute error, and root mean square error is 1.1395%, 0.4916%, and 0.5145% in Beijing Bus Dynamic Stress Test condition, 1.8125%, 0.6329%, and 0.7955% in Dynamic Stress Test condition, compared with the extended Kalman filter, unscented Kalman filter, and particle filter algorithms, all reduced obviously. In the state of health estimation, compared with the Random Forest and adaptive dual extended Kalman filter-based fuzzy inference system, the mean execution time and convergence time are 11.14 seconds and 0.44 second in Dynamic Stress Test condition and 15.17 seconds and 0.63 second in Beijing Bus Dynamic Stress Test condition; the results show lower computation complexity and faster convergence speed, which play an important role in promoting the further application of lithium-ion batteries. Novelty Statement A new forgetting factor dual particle filter algorithm is proposed to realize the co-estimation the battery state of charge and state of health. The capacity and the state of health were estimated for Dynamic Stress Test and Beijing Bus Dynamic Stress Test conditions, respectively, and the estimation results of the two common conditions were analyzed. SOC estimator is impressive for its high accuracy and quick convergence. The estimated SOH information has better convergence performance and shorter running time.

Influence of pore space heterogeneity on mineral dissolution and permeability evolution investigated using lattice Boltzmann method

The influence of pore space heterogeneity on mineral dissolution and permeability evolution in porous media was investigated using a numerical approach. Artificial porous media were generated by the linear Boolean model, and pore heterogeneity was evaluated using the Euler–Poincaré characteristic (i.e., Euler number). We applied the lattice Boltzmann method with dual particle distribution functions to simulate mineral dissolution under the combined effect of fluid flow and a diffusion process. Simulations were conducted to investigate dissolution patterns for a wide range of Péclet (Pe) and Damköhler (Da) numbers and various pore geometries. Six dissolution regimes were observed, and two types of transition phenomena between these dissolution regimes could be characterized. At high Pe and Da, the dissolution patterns strongly depended on the pore heterogeneity. In addition, four types of porosity–permeability relationship were observed. These relationships were influenced by the pore heterogeneity at high Da numbers.

Effect of Dual Particle Size Corundum Particles on the Tribological Properties of LM30 Aluminium Alloy Composites for Brake Rotor Applications

Effect of Dual Particle Size Corundum Particles on the Tribological Properties of LM30 Aluminium Alloy Composites for Brake Rotor Applications

Beyond the Equivalence Principle: Gravitational Magnetic Monopoles

We review the hypothesis of the existence of gravitational magnetic monopoles (H-pole for short) defined in analogy with the Dirac's hypothesis of magnetic monopoles in electrodynamics. These hypothetical dual particles violate the equivalence principle and are accelerated by a gravitational field. We propose an expression for the gravitational force exerted upon an H-pole. According to GR ordinary matter (which we call E-poles) follows geodesics in a background metric. The dual H-poles follows geodesics in an effective metric.

Stimuli-responsive coating by simple physical blending route

The article describes a very simple design philosophy of a coating that responds to temperature-rise by changing its behavior from hydrophilic to superhydrophobic in an instantaneous reversible manner. The material developed can be applied to a variety of surfaces simply by brush or roller, making it highly suitable as the basic ingredient of smart paint. Low surface energy fluoro and amino monomers were introduced to prepare the polymer backbone, which was then used as a binder for achieving a nano-micro dual particle morphology based on nano-silica micro-Titania (pre-functionalized with hydrophobic siloxane) by simple physical blending. The final structure was inspired by the so-called lotus effect. The best designed resulting material shows a water contact angle of 152° with a roll off-angle as low as 2° as a coating in response to elevated temperature, changing its hydrophilic nature. This reversible switching is ascribed to the formation and breaking of hydrogen-bond between amine group (secondary or tertiary) in polymer backbone and water. This bond-breaking introduces a critical change in the roughness of the coating, which was observed using atomic force microscopy. We also show that the response temperature can be tuned, which opens up the possibility of designing country-specific self-cleaning exterior paints.

Effect of fine aggregate replacement with expanded perlite and pumice on the development of lightweight concrete

ABSTRACT In the present study, an attempt has been made to produce lightweight concrete (LWC) by replacing fine aggregates with expanded perlite and pumice. The first set of LWC is prepared by replacing the fine aggregates with expanded perlite at varying proportions, i.e. 0%, 25%, 50%, and 100%. The second set of the mix is prepared to study the effect of replacement of natural sand with equal proportionality of dual particles (expanded perlite and pumice). The replacement of fine aggregate with lightweight aggregates (expanded perlite and pumice) efficiently developed the LWC based on the density specified by Eurocode 2 Part 1–1 (density < 2200 kg/m3). The incorporation of expanded perlite efficiently brought down the density of developed LWC lower than 2200 kg/m3. However, the density of the mix prepared using expanded perlite and pumice exhibited slightly greater than the density of only expanded perlite contained LWC. The incorporation of pumice in the LWC imparts the pozzolanic reactivity and shows better strength and durability properties than the only expanded perlite contained LWC. Furthermore, the microstructure properties revealed that the presence of porous lightweight material unable to improve the interfacial transition zone (ITZ) compared to conventional concrete.

Near infrared dual wavelength micro surface particle laser

Miniaturization and integration of lasers have been a hot topic in recent years. Colloidal quantum dots (CQDS) can be used as laser gain media because of their high luminous efficiency and low threshold. Compact distributed Bragg reflector (DBR) combined with CQDs is used to construct micro laser. In this paper, CdTeSe/ZnS core–shell CQDs were prepared by aqueous synthesis. DBR was fabricated by magnetron sputtering using SiO2 and TiO2 through reasonable design of their thickness and repetition cycle number. CQDs were dropped on the surface of DBR to form a low-cost small-scale surface particle laser (SPL). The output emission of 770 nm and 824 nm dual wavelength laser is realized. The threshold is 11 mW/cm2 and the bandwidth is 1 nm. The micro integrated laser with high intensity and Narrow bandwidth near infrared emission has been completed.

Estimation of state‐of‐energy for lithium batteries based on dual adaptive particle filters considering variable current and noise effects

Estimation of <scp>state‐of‐energy</scp> for lithium batteries based on dual adaptive particle filters considering variable current and noise effects

Anisotropic neutron response of trans-stilbene and impact on a handheld dual particle imager

This manuscript details measurements of the anisotropic light-output response of trans-stilbene, henceforth referred to as stilbene, along the three primary crystal planes and analyzes how this anisotropic response impacts neutron image reconstruction in a handheld dual particle imager (H2DPI). A prototype H2DPI composed of stilbene pillars (6×6×50 mm3) coupled to silicon photomultipliers was built and is capable of imaging both fast neutrons and gamma rays from kilogram quantities of special nuclear material. Stilbene was chosen as the scintillating medium for the imager because of its pulse shape discrimination capability, time resolution and relatively high light output. A drawback to using stilbene, however, is the anisotropic response. A recoiling proton from a neutron elastic-scattering event in stilbene will yield different amounts of scintillation light depending on the direction of the recoiling proton with respect to the crystal lattice. This manuscript analyzes how this anisotropic response impacts neutron image reconstruction in 4π. The light output in the three primary crystal planes of stilbene were independently measured 6–7 times for proton recoil energies ranging from 0.5–5.0 MeV using a quasi-monoenergetic time-of-flight neutron source. The measured light-output data in the three crystal planes were fit with a semi-empirical function based on Birks’ formula. These fits were used to reconstruct the location of a 252Cf source in front of the imager (0°, −0.8°), to the left of the imager (−90°, −0.8°) and directly above the imager (0°, 90°) to determine if it is necessary to apply the directionally-dependent response of stilbene to accurately reconstruct source locations. A bootstrapping technique was applied to the measured data sets to produce 1000 images composed of 2000 cone projections for each source location and each measured light-output curve. List-mode maximum likelihood expectation maximization was applied to each image; the highest pixel location and the full width at half maximum (FWHM) were then recorded. The average and standard deviations of these parameters were taken for each set of images. The maximum difference in the average azimuthal pixel location when varying between the appropriate and incorrect light-output curves for the source locations at (0°, −0.8°) and (−90°, −0.8°) were respectively found to be 1.85±1.39° and 2.03±1.78°. All other pixel locations and FWHMs were within a single standard deviation of uncertainty. Taken together, the anisotropic response of stilbene has negligible impact on the neutron image reconstruction capability of the H2DPI.

Influence of Heat Treatment on Mechanical Characteristics of Al7075/Al2O3/TiC Hybrid Metal Matrix Composite

The present paper deals with the study and characterization of the physical and mechanical behaviors of Al-7075/Al2O3 / TiC hybrid metal matrix composite (HMMC) materials. The assimilation of dual particles like self-lubricated ceramic particles (Al2O3) along with hard particles (TiC) in the Al-7075 matrix is done using liquid stir casting method. The hybrid composite is produced with varying weight percentages of (8, 6, 4, 2, 0) Al2O3 and TiC (0, 2, 4, 6, 8) particulates. The produced Al HMMC materials are subjected to heat treatment (T6). The behavior of properties like density, hardness, impact and tensile strengths are analyzed based on experimentation. The obtained properties of cast Al-7075 HMMC materials are compared with heat treated Al-7075 composite materials. The dispersion of TiC hard particles in ductile Al-7075 matrix, predominates Al2O3 in improving mechanical properties because of its superior properties.

Experimental and numerical study of deposition mechanisms for cold spray additive manufacturing process

Cold spray is an attractive and rapidly developing process for additive manufacturing with high efficiency and precision, repairing and coating, especially in aircraft and aerospace applications. Cold spray additive manufacturing deposits micro-particles with large plastic deformation below their melting point, eliminating heat effect zone which could deteriorate the quality of repairing zone. The particle deposition in cold spray is a complex process which involves high strain rate, high contact pressure and high temperature. Here we develop, utilize and validate a thermo-mechanical model to provide a definitive way to predict deposition mechanics and surface deformation evolution for particle deposition process in cold spray additive manufacturing. Both a single particle and dual particles models were developed to investigate the contact interaction between particle/substrate and particle/particle. Different combinations of particle/substrate materials (Cu/Cu, Al/Al, steel/steel, and nickel/nickel) and process parameters were considered in this study. The experimental study was conducted to validate simulation results, providing useful information for understanding the limitations and challenges associated with cold spray additive manufacturing. The framework provides insights into improving the quality and precision of stress/strain formation, particle interactions and particle deposition in cold spray additive manufacturing process.

Compact lightweight imager of both gamma rays and neutrons based on a pixelated stilbene scintillator coupled to a silicon photomultiplier array

Dual particle imaging, in which both neutrons and gamma-rays in the environment can be individually characterized, is particularly attractive for monitoring mixed radiation emitters such as special nuclear materials (SNM). Effective SNM localization and detection benefits from high instrument sensitivity so that real-time imaging or imaging with a limited number of acquired events is enabled. For portable applications, one also desires a dual particle imager (DPI) that is readily deployable. We have developed a hand-held type DPI equipped with a pixelated stilbene-silicon photomultiplier (SiPM) array module and low sampling-rate analog-to-digital converters (ADCs) processed via a multiplexed readout. The stilbene-SiPM array (12 × 12 pixels) is capable of effectively performing pulse shape discrimination (PSD) between gamma-ray and neutron events and neutron/gamma-ray source localization on the imaging plane, as demonstrated with 252Cf neutron/gamma and 137Cs gamma-ray sources. The low sampling rate ADCs connected to the stilbene-SiPM array module result in a compact instrument with high sensitivity that provides a gamma-ray image of a 137Cs source, producing 6.4 μR/h at 1 m, in less than 69 s. A neutron image for a 3.5 × 105 n/s 252Cf source can also be obtained in less than 6 min at 1 m from the center of the system. The instrument images successfully with field of view of 50° and provides angular resolution of 6.8°.

Magneto-responsive photochromic acrylic copolymer nanoparticles: An investigation into the mutual interactions and photoisomerization kinetics

Photoresponsive and magneto-responsive smart materials have received specific attention. Here, novel bifunctional polyacrylic nanoparticles were prepared via miniemulsion polymerization in which, magnetite nanoparticles (10–15 nm) were resided in the core and poly (methyl methacrylate-co-spiropyran ethyl acrylate) (poly (MMA-co-SPEA)) was located in the shell. Chemical bonding of spiropyran onto the surface of magnetite provided their close vicinity, leading to effective interactions which have not been studied before. The interactions between the excited state of merocyanine (MC) zwitterion from spiropyran (SP) group and magnetic field of the superparamagnetic Fe3O4 NPs were investigated. The results revealed the existence of mutual interactions and successful increment in the absorption intensity (up to 176%) and optical stability, 9% changes in the rate of photoisomerization and increment in the half life time of MC isomers. These were achieved in the presence of magnetite as well as enhancement in the magnetic properties by 10% under UV irradiation at 365 nm. Such synergistic and two-way interactions between magnetic field of the superparamagnetic Fe3O4 NPs and the produced instant dipole moments in MC may offer a new route toward preparation of dual responsive nanocomposite particles for light-triggered magnetic switches, magnetic-triggered photo switches and simultaneous sensing and separation probes.

Multiscale Metal Oxide Particles to Enhance Photocatalytic Antimicrobial Activity against Escherichia coli and M13 Bacteriophage under Dual Ultraviolet Irradiation.

Antimicrobial activity of multiscale metal oxide (MO) particles against Escherichia coli (E. coli) and M13 bacteriophage (phage) was investigated under dual ultraviolet (UV) irradiation. Zinc oxide (ZnO), magnesium oxide (MgO), cuprous oxide (Cu2O), and cupric oxide (CuO) were selected as photocatalytic antimicrobials in MO particles. Physicochemical properties including morphology, particle size/particle size distribution, atomic composition, crystallinity, and porosity were evaluated. Under UV-A and UV-C irradiation with differential UV-C intensities, the antimicrobial activity of MO particles was monitored in E. coli and phage. MO particles had nano-, micro- and nano- to microscale sizes with irregular shapes, composed of atoms as ratios of chemical formulae and presented crystallinity as pure materials. They had wide-range specific surface area levels of 0.40–46.34 m2/g. MO particles themselves showed antibacterial activity against E. coli, which was the highest among the ZnO particles. However, no viral inactivation by MO particles occurred in phage. Under dual UV irradiation, multiscale ZnO and CuO particles had superior antimicrobial activities against E. coli and phage, as mixtures of nano- and microparticles for enhanced photocatalytic antimicrobials. The results showed that the dual UV-multiscale MO particle hybrids exhibit enhanced antibiotic potentials. It can also be applied as a next-generation antibiotic tool in industrial and clinical fields.

Natural particles can armor emulsions against lipid oxidation and coalescence

Traditional functional ingredients, such as conventional emulsifiers (surfactants, animal-derived proteins), and synthetic antioxidants may become obsolete in the development of clean-label, plant-based, sustainable food emulsions. Previously, we showed that tailor-made antioxidant-loaded particles can yield both physically and oxidatively stable emulsions, and we expected that natural particles with related properties could also show these beneficial effects. Here, we investigated Pickering emulsions prepared with natural plant particulate materials. Particles that showed weak aggregation in acidic aqueous media, indicating a relatively hydrophobic surface, were able to physically stabilize oil-in-water emulsions, through either Pickering stabilization (powders of matcha tea, spinach leaves, and spirulina cake), or an increase in viscosity (pineapple fibers). Matcha tea and spinach leaf particle-stabilized emulsions were highly stable to lipid oxidation, as compared to emulsions stabilized by conventional emulsifiers. Taking this dual particle functionality as a starting point for emulsion design is, in our view, essential to achieve clean-label food emulsions.