Uniform Spheres Research Articles

Curcumin loaded Zein-alginate nanogels with “core-shell” structure: formation, characterization and simulated digestion

Zein nanoparticles tend to aggregate in water and are readily digested by enzymes in the gastrointestinal tract. In current study, the Zein-alginate nanogels loaded with curcumin (Cur@ZA) were fabricated with the “core-shell” structure. The Zein “core” was prepared via antisolvent precipitation method, and the alginate gel “shell” was formed by calcium-induced gelation method. The physicochemical properties, microstructure, encapsulation efficiency, stability and simulated digestion characteristics of nanogels were investigated. The results showed that Cur@ZA formed uniform gel spheres with small particle size (415.10 nm), while possessing a dense gel shell on the surface. The Zein “core” and alginate gel “shell” of Cur@ZA are tightly bound to each other by electrostatic adsorption, hydrophobic interaction and hydrogen bonding. Curcumin was able to be loaded in the Cur@ZA nanogels with a higher encapsulation rate (>92 %). Compared with the system which was not induced by calcium ion, the addition of calcium ions improved the photostability and thermal stability of curcumin, and facilitated slow and sustained release of curcumin in the simulated digestion. Therefore, this novel nanogel delivery system has the ideal physicochemical properties, stability and control-release ability, which has the potential to be used in the food industry.

Versatile dual responsive EGCG/Cys nano delivery system for atherosclerosis

Nanocarriers receive tremendous attention in nanomedicine and precision biomedicine, especially cardiovascular diseases. However, the ideal carriers for multiple agents are still got a long way to come. In this work, one REDOX dual responsive nanoparticle was designed and constructed by epigallocatechin gallate (EGCG) and cystamine (Cys). The particles presented uniform sphere, and its diameter was around 200 nm. The drug loading ability of the particles was evaluated using rhodamine 6G (Rh6G), rapamycin (Rapa) and bovine serum albumin as model drugs. The EGCG/Cys particles could intelligently release drugs based on the REDOX level of local environment. The morphology and cell viability results of endothelial cells (ECs) and macrophage cells verified the good biocompatibility of the particles. The biosecurity of the particles was further confirmed by injections in vivo. Moreover, the EGCG/Cys particles could effectively target the injured vascular. These results confirmed that the EGCG/Cys particles could be used as one universal carrier to build nano delivery system for drugs, biological agent and vaccines for targeted treatment of atherosclerosis. The work provides one novel promising universal nanocarrier with good bio-safety for multiple drugs and bio-agents for atherosclerosis treatment.

Rapid Preparation of Uniform High-Crystallized Mesoporous Titania Spheres without High-Temperature Treatment

Rapid Preparation of Uniform High-Crystallized Mesoporous Titania Spheres without High-Temperature Treatment

Light-Triggered Reversible Swelling of Polymeric Spheres via Surfactant-Free RAFT Emulsion Polymerization-Induced Self-Assembly.

Responsive photonic crystals (RPCs) assembled by monodisperse colloidal particles have attracted enormous interest recently due to their tremendous applications in smart devices. Their structural colors can be determined by particle sizes. However, the lack of a reliable way to tune the sizes in situ limits their development. Herein, we present an efficient route to solve this problem through the fabrication of spherical polymeric particles with light-triggered reversible swelling behavior via surfactant-free reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization-induced self-assembly (PISA). Amphiphilic macro-RAFT agents containing azobenzene groups were synthesized and subsequently employed to mediate the polymerization of methyl methacrylate. Uniform submicron spheres were obtained by modulating solid contents and other parameters. Benefiting from the photoisomerization of azobenzene moieties, the particle sizes expanded and contracted upon alternative ultraviolet/visible-light irradiation accordingly. This strategy will be a supplement to the emulsion PISA and especially give aid to the progress of the RPC materials.

A uniform spherical goat (problem): explicit solution for homologous collapse’s radial evolution in time

ABSTRACT The homologous collapse from rest of a uniform density sphere under its self gravity is a well-known toy model for the formation dynamics of astronomical objects ranging from stars to galaxies. Equally well-known is that the evolution of the radius with time cannot be explicitly obtained because of the transcendental nature of the differential equation solution. Rather, both radius and time are written parametrically in terms of the development angle θ. We here present an explicit integral solution for radius as a function of time, exploiting methods from complex analysis recently applied to the mathematically similar ‘geometric goat problem.’ Our solution can be efficiently evaluated using a Fast Fourier Transform and allows for arbitrary sampling in time, with a simple python implementation that is $\sim \, 100\times$ faster than using numerical root-finding to achieve arbitrary sampling. Our explicit solution is advantageous relative to the usual approach of first generating a uniform grid in θ, since this latter results in a non-uniform radial or time sampling, less useful for applications such as generation of sub-grid physics models. This solution is also of interest because it is the e = 1 case of Kepler’s equation. Our subsequent work extends the method here to produce a general one for solving Kepler’s equation, which turns out to be faster than any other currently extant.

Coronary Au@Bi Nanospheres for Highly Impedance‐Sensitive Immunosensing toward CEA

AbstractNovel coronary Au@Bi nanospheres (NSs) are simply synthesized by sparkling gold nanoparticles (Au NPs) on the surface of bismuth (Bi) NSs and successfully used as highly impedance‐sensitive immunosensing platform to develop a new label‐free electrochemical immunosensor for the detection of carcinoembryonic antigen (CEA). Firstly, Bi NSs are prepared by one‐pot hydrothermal method, showing uniform sphere morphology with a dense oxide film formed outside Bi NSs due to the easy oxidation of Bi in the air. The oxide film significantly hinders the transmission of electrons and effectively improves the sensitivity of the proposed electrochemical impedance immunosensor. The surface functionalization of Bi NSs with Au NPs enhances the biocompatibility, stability, as well as active surface area of the produced Au@Bi NSs, preferable for the efficient loading of antibody molecules. The electrochemical impedance spectroscopy (EIS) is selected as the optical technique to measure CEA with the constructed immunosensor based on Au@Bi NSs. Because of the excellent impedance‐responsive performance, this new immunosensor displays highly sensitive detection toward CEA in a linear range of 50 fg mL−1–100 ng mL−1 with an extremely low detection limit of 9.83 fg mL−1 and could be potentially used in early clinical detection of cancer.

Aggregation and Growth Mechanism of Ovalbumin and Sodium Carboxymethylcellulose Colloidal Particles under Thermal Induction.

Ovalbumin (OVA)/sodium carboxymethylcellulose (CMC) colloidal particles were prepared with different compactness and morphologies by regulating the interaction between proteins and polysaccharides during heating. Electrostatic interactions between the amine groups of OVA (-NH3+) and carboxyl groups of CMC (-COO-) enhanced complex formation. The protein conformation change benefited the hydrophobic interaction between the particles. Proteins in colloidal particles were unfolded/folded under thermal induction to form aggregates having more β-sheet structures. When the OVA/CMC ratio was 1:2, the initially loosely connected OVA/CMC aggregation changed into a uniform sphere between 25 and 90 °C. The mass ratio of OVA to CMC within the final colloidal particle (90 °C) was about 1:1.4. The OVA/CMC particle stability was maintained with hydrogen bonding, hydrophobicity, and disulfide bond. When OVA levels were predominant, OVA and CMC developed an approximately hollow sphere. Moreover, the final colloidal particle composition showed the OVA-to-CMC ratio as 3:1 (w/w). OVA bound into colloidal particle pores to increase compactness. Moreover, OVA and CMC bound to the colloidal particle while the particle shrank, thereby increasing the compactness of colloidal particles. There was a significant decrease in ABTS•+ scavenging activity of curcumin compared with that of the particles with a ratio of 1:2. Thus, the rational adjustment of the structure of colloidal particles could effectively enhance their functional characteristics, providing a new way for the controlled release of the active ingredients.

Light scattering of a uniform uniaxial anisotropic sphere by an on-axis high-order Bessel vortex beam.

Analytical solutions to the scattering of a uniform uniaxial anisotropic sphere illuminated by an on-axis high-order Bessel vortex beam (HOBVB) are investigated. Using the vector wave theory, the expansion coefficients of the incident HOBVB in terms of the spherical vector wave functions (SVWFs) are obtained. According to the orthogonality of the associated Legendre function and exponential function, more concise expressions of the expansion coefficients are derived. It can reinterpret the incident HOBVB faster compared with the expansion coefficients of double integral forms. The internal fields of a uniform uniaxial anisotropic sphere are proposed in the integrating form of the SVWFs by introducing the Fourier transform. The differences of scattering characteristics of a uniaxial anisotropic sphere illuminated by a zero-order Bessel beam, Gaussian beam, and HOBVB are exhibited. Influences of the topological charge, conical angle, and particle size parameters on the angle distributions of the radar cross section are analyzed in detail. The scattering and extinction efficiencies varied with the particle radius, conical angle, permeability, and dielectric anisotropy are also discussed. The results provide insights into the scattering and light-matter interactions and may find important applications in optical propagation and optical micromanipulation of biological and anisotropic complex particles.

Chitosan-thymolsulfonephthalein-cobalt nanocomposites for colorimetric detection of sulfide anions in aqueous solution

BackgroundWater pollution by sulfide ions, arising from the exploration and exploitation of sulfide mineral ore, can cause many chronic and acute health challenges. However, owing to the cost of sophisticated equipment and technical expertise required to detect anionic sulfides in water has inspired the preparation of easy-to-use naked-eye colorimetric devices. MethodsIn this study, the functionalization of chitosan solution with thymolsulfonephthalein solution (CFTS) at moderate conditions was utilized for the chemical synthesis of cobalt nanocomposites (CFTS-CoNCs) based chemosensors. ResultsThe prepared material's scanning electron micrograph shows the high Co dispersion on the surface of CFTS with a thorn-shaped morphology in uniform spheres. In contrast, the transmission electron micrograph shows good dispersibility of the tiny rod-like particles distributed on a dendrite-like surface. The interaction of the orange-colored CFTS-CoNCs chemosensor solution with the colorless S2− ions was accompanied by an instant and stable black color change. Furthermore, the selective and sensitive chemosensor could detect ≥ 15 ppm aqueous S2− ions solution at lower pH. The mechanism of detection could be due to a nucleophilic attack of S2− on the cobalt-induced hydroxylmethylpropyl benzoxathiole amine cation giving rise to the strong UV–Vis absorption at 592 nm. ConclusionThe highly selective and sensitive CFTS-CoNCs chemosensor can be applied for real-time and quick on-site analysis. In addition, the colorimetric device will serve as a lifesaver in terms of reducing both time and cost, user-friendly, and hands-on tools for the rapid/accurate detection of sulfide ions in water.

Self-Templated Synthesis of Triphenylene-Based Uniform Hollow Spherical Two-Dimensional Covalent Organic Frameworks for Drug Delivery

Constructing two-dimensional covalent organic frameworks (2DCOFs) with a desirable crystalline structure and morphology is promising but remains a significant challenge. Herein, we report self-templated synthesis of uniform hollow spherical 2DCOFs based on 2,3,6,7,10,11-hexakis(4-aminophenyl) triphenylene. A detailed time-dependent study of hollow sphere formation reveals an intriguing transformation from initial homogeneous solid spheres into uniform hollow spheres with the Ostwald ripening mechanism. Impressively, the resultant spherical 2DCOFs are composed of high crystallinity nanosheets and even hexagonal single crystals, as demonstrated by transmission electron microscopy. Thanks to its uniform morphology and high crystallinity, the pore volume of the obtained 2DCOFs is up to 1.947 cm3 g–1, which makes it function as superior nanocarriers for efficient controlled drug delivery. This result provides an avenue for improving COFs’ performance by regulating their morphology.

Pyridinic Nitrogen Sites Dominated Coordinative Engineering of Subnanometric Pd Clusters for Efficient Alkynes' Semihydrogenation.

Supported metal catalysts have played an important role in optimizing selective semihydrogenation of alkynes for fine chemicals. There into, nitrogen-doped carbons, as a type of promising support materials, have attracted extensive attentions. However, due to the general phenomenon of random doping for nitrogen species in the support, it is still atremendous challenge to finely identify which nitrogen configuration dominates the catalytic property of alkynes' semihydrogenation. Herein, it is reported that uniform mesoporous N-doped carbon spheres derived from mesoporous polypyrrole spheres are used as supports to immobilized subnanometric Pd clusters, which provide a particular platform to research the influence of nitrogen configurations on the alkynes' semihydrogenation. Comprehensive experimental results and density functional theory calculation indicate that pyridinic nitrogen configuration dominates the catalytic behavior of Pd clusters. The high contents of pyridinic nitrogen sites offer abundant coordination sites, which greatly reduces the energy barrier of the rate-determining reaction step and makes Pd clusters own high catalytic activity. The electron effect between pyridinic nitrogen sites and Pd clusters makes the reaction highly selective. Additionally, the good mesostructures also promote the fast transport of substrate. Based on the above, catalyst Pd@PPy-600 exhibits high catalytic activity (99%) and selectivity (96%) for phenylacetylene (C8 H6 ) semihydrogenation.

Self -templated construction of hollow trimetallic MnNiCoP yolk-shell spheres assembled with nanosheets as a satisfactory positive electrode material for hybrid supercapacitors.

Transition metal phosphides (TMPs) demonstrate excellent potential for supercapacitor electrode materials owing to their good theoretical capacity and great electrical conductivity. The electrochemical features of the electrode materials based on monometallic or bimetallic phosphides are not desirable or satisfactory due to their low rate performance, unfavorable energy density, and short durability. One practical solution to overcome the above problems is to bring in heteroatoms to the structure of the bimetallic materials to create trimetallic phosphides. In this work, brand-new MnNiCoP yolk-shell spheres assembled with nanosheets are synthesized in a facile self-templated way using greatly uniform co-glycerate spheres as sacrificial templates, followed by a phosphorization process. Because of the existence of plenty of oxidation-reduction active sites, great surface area (SA) with mesoporous pathways, high electrical conductivity, and synergistic effect of Mn, Ni, and Co atoms, the fabricated MnNiCoP@NiF electrode demonstrates a considerably increased electrochemical efficiency compared with the bimetallic phosphide MnCoP@NiF electrode. Noticeably, the MnNiCoP@NiF electrode exhibits a great specific capacity of 291.24 mA h g-1 at an applied current density of 1 Ag-1, 80% capacity retention at an applied current density of 20 Ag-1, and 91.3% capacity retention after 14 000 cycles. In addition, a hybrid supercapacitor device with a brand-new positive electrode (MnNiCoP@NiF) and an appropriate negative electrode (AC@NiF) demonstrates an energy density of 57.03 W h kg-1 with a power density of 799.98 W kg-1, plus superb cyclability with 88.41% of the primary capacitance after 14 000 cycles.

PH and NIR responsive polydopamine-doped dendritic silica carriers for pesticide delivery

The stimuli-responsive pesticide delivery system provides a powerful strategy for enhancing the effective utilization of pesticides and reducing environmental pollution. Here, we prepared a new polydopamine doped dendritic silica (SiO2/PDA) nanocarriers for pesticide delivery. The SiO2/PDA nanocarriers present uniform spheres with an average diameter of 250 nm and carry center-radial inner pores. After loading dinotefuran (DNF) insecticide, polyethyleneimine (PEI) was used to cap the loaded-pesticide pores. The resulting SiO2/PDA@PEI displays high photothermal conversion effect (η = 35.1 %) and pH and near infrared (NIR) light-responsive release behavior. Meanwhile, the SiO2/PDA and SiO2/PDA@PEI carriers displayed high adhesion and wettability to leaves, and the photostability of DNF encapsulated in SiO2/PDA@PEI was improved by nearly 10 times greater than for free DNF. Importantly, the SiO2/PDA carriers possessed a benign biocompatibility on Escherichia coli (E. coli), seed and cells. Therefore, this work provides a promising approach to improve the utilization of pesticide.

A Physical Framework to Interpret the Effects of High Permittivity Materials on Radiofrequency Coil Performance in Magnetic Resonance Imaging.

We propose a framework to interpret the effects of High Permittivity Materials (HPM) on the performance of radiofrequency coils in Magnetic Resonance Imaging (MRI). Based on a recent formulation of the scattering and propagation properties of spheres, we expanded the field in a layered sphere as a superposition of ingoing and outgoing travelling waves, which allowed us to study the field components with a non-homogeneous transmission line model. We investigated the effects of a layer of HPM surrounding a head-mimicking uniform sphere at 7 tesla. Through the analysis of impedance and reflection coefficients, we show that by adjusting the properties of the HPM, it is possible to selectively amplify individual modes, or combination of them, modifying the overall field distribution in the sample and increasing signal-to-noise ratio at specific locations. Our results demonstrate that the observed enhanced MRI performance is not merely due to secondary fields generated by displacement currents in the HPM. Our formulation explains the effect of HPM in terms of matching, enabling the optimization of the electrical properties of the HPM with a simple mode-matching formula. The proposed method could guide the design of novel radiofrequency coils with integrated HPM.

In situ decoration of Co3O4 on N-doped hollow carbon sphere as an effective bifunctional oxygen electrocatalyst for oxygen evolution and oxygen reduction reactions

Transition metal oxide based materials are believed as a sustainable and effective electrocatalysts for oxygen evolution and oxygen reduction reactions (OER/ORR). However, poor conductivity, specific surface area, and tunable crystallography are major bottlenecks. To alleviate such issues, we developed a highly active spinel Co3O4 decorated N-doped hollow carbon sphere (Co3O4/NHCS) by single step decoration using cobalt phthalocyanine (CoPc) precursor for the first time. The introduction of various extents of CoPc significantly affects the sphere wall thickness, defect sites, doping amount of cobalt content, and the concentration of Co3+ and Co2+ sites. The resulting optimum loading of 0.2 g of Co3O4/NHCS-0.2, exhibits a highly uniform hollow carbon sphere with a high wall thickness (61 nm), better surface area (445 m2 g−1), and moderate defect sites. Notably, an exterior concentration of octahedral Co3+ (35.50%) and tetrahedral Co2+ (26.54%) sites serve as the active centres for OER and ORR, respectively. Remarkably, the obtained material exhibits exceptional OER performance with a potential of 1.80 V vs. RHE in 0.1 M KOH medium for achieving a current density of 10 mA cm−2, outperforming the benchmark RuO2 material. In addition, Co3O4/NHCS-0.2 demonstrates an impressive ORR electrocatalytic activity with onset potential of 0.89 V vs. RHE, excellent current density of 5.0 mA cm−2, lower Tafel slope of 60 mV dec−1 and close to four electron transfer. Moreover, the moderate carrier concentration, flat band potential, higher tetrahedral Co2+ and pyridinic N sites significantly improved the ORR activity and methanol oxidation tolerance ability.

Study on preparation and characterisation of pure and lithium incorporated SnS thin films for solar cell applications

A ternary transition metal sulfide was synthesized and characterized by the sonochemical approach in this study, namely a Li (Li) and tin sulfide (SnS) thin film incorporating lithium (Li). Lithium incorporated SnS thin films (Li-SnS) were synthesized by equal molar ratios used in the synthesis approach. In these prepared thin films, the crystallite size averaged 5 nm and the thin films were of good crystalline nature. Nanoparticles in the thin film samples have a uniform sphere shape, with clusters forming in a few places, as seen by FE-SEM images. The presence of Li, Sn and S was confirmed through XRF spectral analysis. From the fingerprint region of the FTIR spectra, the presence of Ni, Li, Sn and sulphur was confirmed and no other impurities were detected. The UV absorption analysis was highly indicating the enhanced photon absorption behaviour of the prepared thin film samples due to the incorporation of Li with SnS samples. The efficiencies of the solar cell fabricated with SnS, Li-SnS, were found to be 6.21 and 7.92 %. From the results it is concluded that Li-SnS thin film samples can be a potential candidate for use as an electrode in solar cell applications

Relativistic adapted Gaussian basis sets free of variational prolapse of small and medium size for hydrogen through xenon.

Two new relativistic adapted Gaussian basis sets of small and medium size are presented for all elements from Hydrogen through Xenon. These sets are free of variational prolapse and were developed with the polynomial generator coordinate Dirac-Fock method to be used with two finite nuclear models, uniform sphere and Gaussian. The largest basis set errors for electronic configurations from the Aufbau principle are around 10.0 and 4.7 mHartree for the small- and medium-size sets, respectively, which is in accordance with the accuracy level expected in each case. Hence, to our knowledge, these are the smallest prolapse free basis sets developed for these elements.

Ordered packing of uniform spheres via random packing protocol

The packing structure of granular materials is crucial to their performance. Uniform granular spheres always form a disordered packing when randomly fed into a container, which is considered as a natural consequence and a prototype of glass transition. This paper presents a method to design containers to promote ordered packings. In a particular container, mono-sized granular spheres can self-assemble into a single crystal without human interventions when randomly fed at a small rate, and hence achieve much higher packing density than the normally obtained random packings. The container is designed to achieve the consistency of ordered structures formed on the boundary and at the centre, so that a new particle can always be assembled into a crystal lattice node simply by gravity. Such container is generally effective for the self-assembly of uniform size spheres of different material properties (density, friction coefficients, size, etc.). Similarly designed containers can also be very effective to achieve ordered packings under vibration, which provides a method to densify packed beds of granular particles. Moreover, the finding indicates that glass transition or crystallisation could result from boundary symmetry in addition to other factors. It also suggests a way to design boundaries to promote the self-assembly of particles in general.

Spacecraft Geometry Effects on Kinetic Impactor Missions

The DART (Double Asteroid Redirection Test) mission will impact a spacecraft on the secondary (Dimorphos) of the binary asteroid system Didymos in 2022 September, with the goal of altering the orbital period of Dimorphos about Didymos sufficiently to be observed from ground-based observations. Numerical impact modeling is a crucial component in understanding the outcome of the DART experiment, and while many have investigated the effects of target properties, such as material strength and porosity (which remain unknown), an often overlooked factor is the importance of accurately representing the spacecraft itself in such models. Most impact modeling to date has considered simple impactor geometries such as a solid uniform sphere, but in reality the spacecraft is a complex shape full of different components, open spaces, and thin walled structures. At a minimum, a simple solid representation underestimates the surface area of the impact: for a small body such as Dimorphos (approximately 160 m in diameter), the difference between a spacecraft spanning 20 m (including solar arrays) impacting and a sub-1 m idealized shape may be important. In this paper, we compare models impacting high-fidelity models of the spacecraft based on the CAD geometry with various simplified impactors, in order to assess the potential importance of this effect. We find that the difference between the simplest impactor geometries (such as a uniform sphere) and the real spacecraft is measurable, and has an interesting dependence on the material properties of the asteroid itself.

Neutron star crust properties: comparison between the compressible liquid-drop model and the extended Thomas-Fermi approach

We present a detailed analysis of three models predicting the properties of non-uniform matter in the crust of neutron stars: the compressible liquid-drop model, the fourth order Extended Thomas Fermi (ETF) method, and ETF plus Strutinsky integral (ETFSI) correction. The former treats the nuclear clusters as uniform hard spheres, the second takes into account the density distribution which can be different for neutrons and protons, and the last one includes the proton shell effects within the Strutinsky approach. The purpose of this work is to understand the importance of the improvements in the nuclear modeling and to analyze the quantities which are the most sensitive to them. We find that thermodynamic quantities such as pressure, energy and chemical potential, as well as the electron fraction, are in very good agreement among the three models. This confirms previous results where we have shown that the improvement in the finite-size description of the nuclear clusters has a small impact on these quantities, since they are mainly constrained by the bulk properties. The refinements in the finite-size modeling are shown to impact mostly the composition of the nuclear clusters (Z cl, N cl) in an ordering which ranks according to the leptodermous expansion. This analysis is performed considering both the r-cluster and the e-cluster representations. The proton shell effects are shown to stabilize Z cl, which consequently impacts the neutron number N cl as well.