Large Size Distribution Research Articles

Effect of Phosphate and Ferritin Subunit Composition on the Kinetics, Structure, and Reactivity of the Iron Core in Human Homo- and Heteropolymer Ferritins.

Ferritins are highly conserved supramolecular protein nanostructures that play a key role in iron homeostasis. Thousands of iron atoms can be stored inside their hollow cavity as a hydrated ferric oxyhydroxide mineral. Although phosphate associates with the ferritin iron nanoparticles, the effect of physiological concentrations on the kinetics, structure, and reactivity of ferritin iron cores has not yet been explored. Here, the iron loading and mobilization kinetics were studied in the presence of 1-10 mM phosphate using homopolymer and heteropolymer ferritins having different H to L subunit ratios. In the absence of ferritin, phosphate enhances the rate of ferrous ion oxidation and forms large and soluble polymeric Fe(III)-phosphate species. In the presence of phosphate, Fe(II) oxidation and core formation in ferritin is significantly accelerated with oxidation rates several-fold higher than with phosphate alone. High-angle annular dark-field scanning transmission electron microscopy measurements revealed a strong phosphate effect on both the size and morphology of the iron mineral in H-rich (but not L-rich) ferritins. While iron nanoparticles in L-rich ferritins have spherical shape in the absence and presence of phosphate, iron nanoparticles in H-rich ferritins change from irregular shapes in the absence of phosphate to spherical particles in the presence of phosphate with larger size distribution and smaller particle size. In the presence of phosphate, the kinetics of iron-reductive mobilization from ferritin releases twice as much iron than in its absence. Altogether, our results demonstrate an important role for phosphate, and the ferritin H and L subunit composition toward the kinetics of iron oxidation and removal from ferritin, as well as the structure and reactivity of the iron mineral, and may have an important implication on ferritin iron management in vivo.

High performance supercapacitors using selenium partially reduced Co3O4 on carbon cloth electrode with 3D interconnected architecture nanowires

The electrodes with high conductivity, large specific surface area and homogeneous pore size distribution are greatly desirable for supercapacitors applications. Herein, a hydrothermal and subsequent annealing approach was adopted to fabricate 3D interconnected nanowires architecture of selenium partially reduced spinel Co3O4 grew on the carbon cloth (COS@CC). The binder-free COS@CC electrode displays excellent specific capacitance, 1046.9 C g−1 at 1 A g−1, superior rate capability, 51.6% capacitance retention and superior cyclic stability, 92.0% capacitance retention after 15,000 cycles. These electrochemical performances were found to be better than that of the Co3O4@CC electrode. The enhanced electrochemical performance was ascribed to the fact that 3D interconnected architecture nanowires could shorten the ion transfer distance and heighten the rate of the redox reaction. In addition, increased specific surface area and homogeneous mesopore size distribution could assist effective diffusion and transfer of OH– between electrodes and electrolyte. The enhancement of conductivity, which is caused by the selenium partial reduction and more oxygen vacancies in the structure, facilitates electrons transfer and consequently improves the electrochemical properties of supercapacitors. These remarkable electrochemical performances indicate that the CSO@CC can be employed for developing high-energy and power-density supercapacitors.

Test method for abrasion behavior of tire tread compounds using the wear particles

The abrasion behavior of model tire tread compounds was characterized by the shapes and size distributions of their wear particles. Carbon black-filled NR/BR vulcanizates with varying compositions (NR/BR = 100/0, 80/20, and 60/40) were used. These were thermally aged at 80 °C for 30 days. The wear particles produced from the aged specimen had rougher shapes than those produced from the unaged specimen. The size distributions of wear particles for the aged specimen were smaller than those for the unaged specimen. The wear particles produced from the NR = 100 sample had a larger size distribution than those produced from the NR/BR blend samples. The size distributions of wear particles smaller than 500 μm were found to be closely related to the crosslink density irrespective of the rubber composition and thermal aging. The aged samples exhibited narrower abrasion patterns than their unaged samples. Furthermore, the spacing and depth decreased as the BR content increased. The abrasion patterns were closely related to the size distributions of wear particles. The abrasion rates and the number of wear particles significantly increased after the thermal aging. The abrasion behavior was mainly affected by the crosslink density, rubber composition, presence of antidegradants, and tensile strength. By analyzing the shapes and size distributions of the wear particles and the crosslink densities, the abrasion behavior could be further elucidated.

Structural and magnetic properties comparison between cobalt ferrite films obtained by different deposit method

We presented a comparison of the structural, morphological, and magnetic properties between films of cobalt ferrite oxide (CFO), these were deposited with pulsed laser deposition (PLD) and spin-coating (SC) technique. In CFO films obtained by PLD method, a preferential orientation is clearly observed in (004) planes, with a large grain size distribution associated with the splashing effect. For the CFO films obtained by SC method have a homogeneous microstructural distribution with grain size around 50 nm. Additionally, Raman spectra deconvolution was used to estimate the cation distribution in CFO films. Magnetic measurement of CFO films obtained by SC shows a coercive field increment, and which that can be due to a reinforcement in magnetocrystalline anisotropy due to the homogeneous microstructure, whereas for CFO films obtained by PLD, it shows a coercive field decrement due to the splashing effect.

New superdielectric materials: (1-x) SrFe12O19 – x BNT-BT nanocomposites

Novel (1-x) SrFe12O19 – x BNT-BT0.08 (x = 0; 0.5; 0.8; 1) nanocomposites were explored in this study. The samples were produced by sol-gel method and compacted by conventional sintering. The composition, morphology, local structure, dielectric and magnetic properties were investigated by X-ray diffraction, Transmission Electron Microscopy, Impedance Analysis, Mössbauer spectroscopy, and SQUID magnetometry. The desired composition and the presence of the magnetoplumbite SrFe12O19 and perovskite BNT-BT structures were verified by X-ray diffraction. Irregular morphology and large size distributions are evidenced in the electron microscopy micrographs. The reported room temperature dielectric constants in this study are the highest values obtained in multiferroic composites at room temperature: giant dielectric constants (∼1.3 × 106) were obtained, relative to 0.13 × 104 in BNT-BT. The hyperfine parameters allowed the identification of the Wyckoff positions of the Fe ions corresponding closely to the theoretical case. The hard magnetic character of the SrFe12O19 phase is evidenced from the magnetic measurements. For the first time in multiferroic composites, superdielectric characteristics are evidenced at room temperature.

Room-temperature high-precision printing of flexible wireless electronics based on MXene inks

Wireless technologies-supported printed flexible electronics are crucial for the Internet of Things (IoTs), human-machine interaction, wearable and biomedical applications. However, the challenges to existing printing approaches remain, such as low printing precision, difficulty in conformal printing, complex ink formulations and processes. Here we present a room-temperature direct printing strategy for flexible wireless electronics, where distinct high-performance functional modules (e.g., antennas, micro-supercapacitors, and sensors) can be fabricated with high resolution and further integrated on various flat/curved substrates. The additive-free titanium carbide (Ti3C2Tx) MXene aqueous inks are regulated with large single-layer ratio (>90%) and narrow flake size distribution, offering metallic conductivity (~6, 900 S cm−1) in the ultrafine-printed tracks (3 μm line gap and 0.43% spatial uniformity) without annealing. In particular, we build an all-MXene-printed integrated system capable of wireless communication, energy harvesting, and smart sensing. This work opens a door for high-precision additive manufacturing of printed wireless electronics at room temperature.

In Vitro High-Throughput Toxicological Assessment of Nanoplastics.

Sub-micrometer particles derived from the fragmentation of plastics in the environment can enter the food chain and reach humans, posing significant health risks. To date, there is a lack of adequate toxicological assessment of the effects of nanoplastics (NPs) in mammalian systems, particularly in humans. In this work, we evaluated the potential toxic effects of three different NPs in vitro: two NPs obtained by laser ablation (polycarbonate (PC) and polyethylene terephthalate (PET1)) and one (PET2) produced by nanoprecipitation. The physicochemical characterization of the NPs showed a smaller size, a larger size distribution, and a higher degree of surface oxidation for the particles produced by laser ablation. Toxicological evaluation performed on human cell line models (HePG2 and Caco-2) showed a higher toxic effect for the particles synthesized by laser ablation, with PC more toxic than PET. Interestingly, on differentiated Caco-2 cells, a conventional intestinal barrier model, none of the NPs produced toxic effects. This work wants to contribute to increase knowledge on the potential risks posed by NPs.

Hydrodynamics of gas-solid fluidization at ultra-high temperatures

The interest in processing granular materials in fluidized beds at ultra-high temperatures has grown recently to reduce energy consumption and CO2 emissions in relation to numerous high-temperature solid-state reactions. The present research focuses on understanding the hydrodynamics of gas-solid fluidization at temperatures up to 1650 °C to aid the development of ultra-high temperature fluidized bed reactors. Experiments are conducted in a fluidized bed of 30 mm diameter at temperatures up to 1650 °C with corundum and magnesite oxide particles. The fluidization stability is examined based on bed pressure drop measurements using a non-isothermal experimental method. The results demonstrate that stable fluidization of these particles at ultra-high temperatures can be attained by using particles of large and broad size distribution and operating at sufficiently high gas velocities. This article also discusses the bed pressure drop fluctuation, minimum fluidization velocity, and pressure drop offset at ultra-high temperatures.

Analysis of Pore Structure and Thaw Settlement Characteristics of Frozen Silty Sand Based on Computer-Assisted Pulse Nuclear Magnetic Resonance

Computer-assisted pulse nuclear magnetic resonance (NMR) can be used to get important parameters for pore structure characteristics of porous materials. In order to fully understand the effect of frozen soil thaw settlement, the mechanism of artificially frozen soil thaw settlement was examined from a microscopic perspective in conjunction with the frozen soil thaw settlement test. Additionally, to have a better understanding of how pore features change during the thaw settling process, the evolution of the pore size distribution in silty sand was studied. The findings demonstrate the porosity is obviously larger than the initial porosity after freeze-thaw, and the evolution of thaw settlement displacement is related to the change in porosity as thawing progresses, which grows exponentially with porosity. The fraction of medium and large pores (>0.1 μm) in the soil increases significantly during the thawing process. Accordingly, there is a slight increase in the proportion of pores (<0.1 μm) during the thawing progress. The variation in the pore size distribution of silty sand is compatible with that in settlement displacement during the thawing process. Additionally, the thaw settling rate’s development law is consistent with that of the proportion of pores. The number of medium and large pores is critical in determining the rate of thaw settlement. In other words, the development law of thaw settlement rate is consistent with the development law of medium and large pore size distribution.

Influence of Non-Rubber Components on the Properties of Unvulcanized Natural Rubber from Different Clones.

Natural rubber from different Hevea braziliensis clones, namely RRIM600, RRIT251, PB235 and BPM24, exhibit unique properties. The influences of the various fresh natural rubber latex and cream concentrated latex on the non-rubber components related properties were studied. It was found that the fresh natural rubber latex exhibited differences in their particle size, which was attributed to the non-rubber and unique signature of clones which affect various properties. Meanwhile, the cream concentrated latex showed the protein contents, surface tension, and color of creamed latex to be lower than the fresh natural latex. However, TSC, DRC, viscosity, particle size and green strength of concentrated latex were found to be higher than the fresh natural latex. This is attributed to the incorporation of HEC molecules. Also, the rubber particle size distribution in the RRIM600 clone exhibited a large particle size and uniform distribution, showing good mechanical properties when compared to the other clones. Furthermore, the increased green strength in the RRIM600 clone can be attributed to the crystallization of the chain on straining and chain entanglement. These experimental results may provide benefits for manufacturing rubber products, which can be selected from a suitable clone.

Growth Characteristic Analysis of Haematococcus pluvialis in a Microfluidic Chip Using Digital in-Line Holographic Flow Cytometry.

In order to obtain high yield of astaxanthin, a high-value compound with ultrastrong antioxidant capacity, it is necessary to identify the growth characteristics (biomass, morphology, and size) of Haematococcus pluvialis. The current detection methods have the disadvantages of labor-consuming operation or complicated measurement system. It is an urgent need to explore a simple and cost-effective method for the detection of H. pluvialis with large size distribution during its growth period. In this work, a digital in-line holographic flow cytometry using a linear array sensor is proposed to measure the growth characteristics of H. pluvialis in a two-dimensional (2-D) hydrodynamic focusing microfluidic chip. Based on the modified angular spectrum method, the distorting holograms caused by the asynchrony of sample flow velocity and acquisition speed of the linear array sensor were rectified and reconstructed. In addition, the depth-of-focus of the imaging system were digitally extended to cover the entire depth of the microfluidic channel for optimized imaging quality. We have utilized the proposed method to statistically investigate the biomass, morphology and size of H. pluvialis under different culture conditions and growth durations.

The promotional role of Nd on the catalytic activity and hydrothermal stability of Cu-SAPO-18 catalyst for NH3-SCR reaction

The Cu-SAPO-18 was prepared by the one-pot method and modified through hydrothermal post-treatment, metal-doped Nd(x)/Cu-SAPO-18 (x = 0.4, 0.8, 1.2, 1.6) catalysts were obtained. The catalytic performance of fresh and aged Nd(x)/Cu-SAPO-18 was evaluated by ammonia selective catalytic reduction (NH3-SCR) reaction. The NOx conversion rate of Nd (1.2)/Cu-SAPO-18 was highest. More than 94.5% NOx conversion was maintained over the aged Nd(x)/Cu-SAPO-18 during 250–450°C, which was almost 10% higher than the conversion of aged Cu-SAPO-18. Various techniques including XRD, XRF, BET, SEM, 27Al MAS NMR, XPS, UV-vis, NH3-TPD, H2-TPR, were applied to explore the effect of Nd content on the physiochemistry property of Cu-SAPO-18. The addition of Nd effectively maintained the relatively large specific surface area and uniform pore size distribution. Moreover, the dealumination progress of Cu-SAPO-18 was mitigated and the aggregation of copper species during hydrothermal aging process was restrained. Thus, Nd(x)/Cu-SAPO-18 owed less CuOx and more amount of isolated Cu2+ ions, which stabilized catalyst structure by entering the double 6-membered ring (D6R). Meanwhile, the incorporation of Nd enhanced the redox property and stabilised surface acid sites of Cu-SAPO-18, which were responsible for facilitating the adsorption and activation of reactants.

NiS2 nanodots on N,S-doped graphene synthesized via interlayer confinement for enhanced lithium-/sodium-ion storage

Rational design of high-capacity nanosized composites as anode nanomaterials is crucial to boosting electrochemical performances towards large-scale application for lithium- and sodium-ion batteries (LIBs and SIBs). The small sizes and homogeneous dimensional size distributions are achieved typically by either the surface confinement on the underlying supports, or the encapsulation confinement within the precursors (such as metal-organic frameworks). Herein, we report the ultrasmall NiS2 nanodots on reduced graphene oxide (NiS2/N,S-rGO) synthesized via interlayer confinement as anode nanomaterials for LIBs and SIBs. The composite is synthesized by pyrolyzing a host/guest precursor of sodium dodecyl sulfate ion/[NiEDTA]2− anions co-intercalated MgAl-layered double hydroxide LDH host, without additional sulfur source. The host/guest-derived interlayer nanoconfinement enables the composite to integrate the advantageous features: low-content active NiS2 nanodots (11.0 wt%) with a mean size of 3.8 ± 0.5 nm, high-content N,S-rGO (89.0 wt%), as well as a large specific surface area and mesopore size distribution. The composite used as anode nanomaterial exhibits reversible capacities of 801.2 mAh g−1 after 100 cycles at 100 mA g−1 for LIBs, and 207.7 mAh g−1 after 200 cycles at 0.1 A g−1 for SIBs, which are greatly higher than those of the pristine N,S-rGO without NiS2 nanodots. The enhancement is experimentally supported by the low charge transfer resistance, high capacitive-controlled contribution, and good structural stability. Our guest/host-based interlayer nanoconfinement can promise an effective synthesis strategy for designing various nanosized anodes for electrochemical energy storage.

Development of encapsulated sage extract powder: Inter-comparison with commercially available powder for physical properties and metabolites composition

Encapsulated Salvia officinalis L. powder (SESP) was developed from extract obtained by supercritical fluid extraction (SFE), and it was compared with commercial sage powder of hydro-distillation extract (HESP). The optimised conditions of 30 MPa at 50 °C for laboratory scale SFE extraction were found to generate the highest yield at 40.96 ± 0.84%. The conditions were later applied in the upscaled extraction, which yielded about 30.10 ± 1.33% extract. Large particle size distribution at 118.46 ± 6.63 µm for SESP was notified as compared to 66.80 ± 1.50 µm for HESP. Outcomes of crystallographic analysis demonstrated that abundant metabolites from various groups existed in both powders. About 25 and 43 metabolites were identified by Gas Chromatography-Mass Spectrometry (GC–MS) in HESP and SESP, respectively. In HESP, organic acids were found to be the major group identified, while terpenoids were the largest group found in SESP.

Poly(acrylic acid) Enabling the Synthesis of Highly Uniform Silica Nanoparticles of sub‐100 nm

AbstractRobust synthesis of small colloidal silica (SiO2) nanoparticles with narrow size distributions (<5%) is challenging because the possible involvement of continuous nucleation and growth of SiO2 in the widely used Stöber process usually results in silica nanoparticles with large sizes and broad size distributions. Promoting heterogeneous nucleation and growth of silica is promising to tackle the challenges by in‐situ forming transient colloidal seeds that provide nucleation surfaces for silica condensate. In this work, poly(acrylic acid) (PAA) is introduced to the Stöber synthesis solutions, which are usually composed of ethanol (containing a trace amount of water), tetraethyl orthosilicate (TEOS), and ammonia, to mediate the nucleation of TEOS hydrolysates and growth of SiO2 nanoparticles. PAA reacts with ammonia to form soft PAA‐NH3 complex colloids that serve as transient seeds to facilitate heterogeneous nucleation and growth of SiO2 nanoparticles after adding TEOS to the synthesis solution. The number of PAA‐NH3 complex colloidal particles, which strongly depends on the molar ratio of PAA and ammonia, determines the number of the resulting SiO2 nanoparticles and thus the size of the SiO2 nanoparticles correspondingly according to the supply of TEOS. Highly uniform SiO2 nanoparticles with finely tuned diameters in the sub‐100 region have been successfully synthesized, and the synthesis protocol is feasible to be scaled up while maintaining the high quality of SiO2 nanoparticles.

Novel Learnings of Proppant Transport Behavior in Unconventional Hydraulic Fractures

Summary Effective proppant placement has been one of the key objectives of hydraulic fracturing. Different proppant and fracture fluid characteristics and placement methodologies have been historically applied based on learnings from standard proppant transport studies with parallel plate slots. The standard test setup represents a simplified planar fracture with constant width and confined height, incorporating only basic flow characteristics, and thus, is inadequate to capture unique phenomena of proppant transport in unconventional reservoirs. In this study, proppant transport laboratory tests were conducted on a large-scale (10×20 ft) tortuous slot flow system. This novel setup incorporates many significant unconventional fracture features, including lateral and vertical tortuosity, variable width, leakoff, fluid dynamics replicating upward fracture growth, and so on. Proppant transport behavior was investigated with multiple parameters such as proppant size, density, and concentration; fracture fluid type and viscosity; pumping sequence; pump rate; and fracture properties (width, leakoff location and rate, fracture tortuosity profile, and flow directions). The detailed parametric and integrated study of test results includes analysis of proppant dune evolution, dune shape, particle-size distribution across dune, propped area, fluid, and proppant collected from leakoff and exit ports. Multiple unique phenomena occurring at tortuous interfaces were observed, including the generation of isolated pockets of proppant pack, restriction of upward movement owing to proppant bridging, and creation of discontinuous and sparsely distributed proppant pillars above the dune. The test results demonstrated a larger proppant dune angle in front of the dune peak during injection and a subsequent falloff of proppant pack with a higher percentage of smaller mesh proppant backfilling the area at and near the inlet (analogous to the wellbore). Self-segregation of proppant in slickwater as per mesh size resulted in higher percentage of smaller mesh (larger size) proppant settled near the injection point, and a higher percentage of larger mesh (smaller size) proppant placed farther in the system. These observations and novel learnings highlight that it is critical to account for tortuous fracture pathway, leakoff effects, and flow directions (both lateral and upward) to better understand proppant transport behaviors in unconventional fractures. A partially proppant-filled fracture area is recognized in unconventional fracture in addition to general classification of propped and unpropped fracture area. Using proppant with large mesh size distribution range or pumping smaller mesh proppant first in slickwater helps achieve dual benefits of higher near-wellbore conductivity and improved far-field transport. This study demonstrates and physically verifies unique proppant transport behaviors in unconventional hydraulic fractures. It also provides novel learnings that will help the industry to optimize hydraulic fracture design through the selection of optimum proppant and fluid properties with enhanced pumping strategies for overall well productivity improvement in an unconventional reservoir.

A scoping review on the biomedical applications of polymeric particles

Composites of nanofiber, nanogel, and microgels for the delivery of doxorubicin, paclitaxel, and other drugs, enhance their solubility, onsite targeted delivery, and therapeutic potency in targeted sites. Thanks to their properties. The ability of the polymer-based delivery vehicles to target specific tissues for therapeutic drug deliveries make the challenges of low binding, large size distribution and others, less significant. A scoping review assisted us to determine the coverage of the literature on biomedical application of nanofiber, nanogel, and microgels composites, by mapping the available evidence and identifying knowledge gaps. Research questions and limitations of current literature were answered.

Construction of porous poly (aryl sulfide sulfone) film with low dielectric constant and excellent mechanical property

AbstractThe low dielectric constant and excellent mechanical property polymer film plays important roles in the high‐speed integrated circuits. In this work, porous poly (aryl sulfide sulfone) (PASS) films with different pore regularities and distributions were systematically fabricated via a combination process with solvent evaporation, wet induced phase separation, and hot pressing. It is found that the macroporous structure of PASS films changed from irregular shape with large pore size distribution to regular shape with small pore size distribution and the sponge‐like pore structure disappeared then formed a dense layer by controlling the time of solvent evaporation and hot pressing, to realize the effective control of the pore structure. The optimal PASS porous film D3 which was heated for 25 min and then hot pressed for 4 min has a low dielectric constant (2.44) and dielectric loss (0.010), high tensile strength (62.14 MPa) and breakdown strength (139.32 kV/mm), and low water absorption (0.54%). The comprehensive excellent properties are beneficial to the application of PASS films in microelectronic devices.

Substrate depended chemical composition segregation and electrical property of perovskite films

Morphology and chemical composition of the CH3NH3PbI3 films on bare glass and indium tin oxide (ITO) are investigated. The film on bare glass is smoother with a narrow grain size distribution, while the one on ITO is rougher with a large grain size distribution. Energy-dispersive X-ray and X-ray photoelectron spectra reveal that there is a superstoichiometric ratio of CH3NH3+ cations in the upper part of the CH3NH3PbI3 film deposited on ITO. Such a chemical composition segregation originates from the higher affinity of PbI2 to ITO. It is demonstrated that the CH3NH3+ cations can migrate to cathode under applied positive bias, which forms an ionic conductivity and increases the current of the device. Thus the device is in a high conductivity state. A large number of CH3NH3+ cations accumulated near the cathode forms a build-in electric field with a direction opposite to the external field. This restricts further migration of the CH3NH3+ cations and the device turns to a low conductivity state. The migration and accumulation of the CH3NH3+ cations manipulate the device to switch between the high and low conductivity states, endowing the device working as a memristor.

Development and preliminary application of deterministic code NECP-FISH for neutronics analysis of fusion-reactor blanket

The fusion-reactor blanket is very important, as it is responsible for the tritium self-sustaining, energy gain, and radiation shielding. Due to the complex structure, large geometry size and inhomogeneous neutron-flux distribution, the Monte-Carlo method is widely used for the neutronics analysis of fusion-reactor blanket, but it takes a large amount of computational time for acceptable simulation results. The deterministic code is the better choice for the fusion-reactor blanket. The geometry capability and accuracy limitation are the most important issues for the deterministic code to simulate the fusion-reactor blanket. Therefore, the newly deterministic code named NECP-FISH has been developed for the fusion-reactor blanket, in which the spherical harmonic function and finite element method were applied. Moreover, the open-source platform SALOME has been applied to generate the complex geometry as pre-process of NECP-FISH. As code verification, NECP-FISH has been applied to simulate the Breeding Unit of HCCB-DEMO, using Monte-Carlo code to provide the reference results. It can be observed that the simulation results of the tritium breeding ratio (TBR), neutron flux and heat release rate provided by NECP-FISH are agreed well with corresponding values by the Monte-Carlo code.