Regular Spheres Research Articles

Thermo-sensitive complex micelles from sodium alginate-graft-poly(N-isopropylacrylamide) for drug release

Polymer micelles with environmentally sensitive properties have potential applications in biomedicine. In this paper, thermo-sensitive complex micelles assembled from biocompatible graft copolymers sodium alginate-graft-poly(N-isopropylacrylamide) (SA-g-PNIPAM) and divalent metal ions were prepared for controlled drug release. The polymer micelles had core-corona structure, which was constituted by metal ions (Ba2+, Zn2+, Co2+) cross-linked sodium alginate as the core and thermo-sensitive PNIPAM chains as the corona. Formation of polymer micelles was determined by Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The polymer micelles were observed as regular spheres with good polydispersity and excellent performance on drug encapsulation and release ability. The cumulative release of 5-fluorouracil (5-FU) from micelles was controlled by pH, ionic strength or temperature of surroundings. The superior properties of sensitive polymer micelles induced by metal ions are expected to be utilized in controlled drug delivery systems.

Microencapsulation of n-dodecane into zirconia shell doped with rare earth: Design and synthesis of bifunctional microcapsules for photoluminescence enhancement and thermal energy storage

We have designed a new type of bifunctional microcapsules composed of an n-dodecane PCM (phase change material) core and a rare-earth-doped zirconia shell for photoluminescence enhancement and thermal energy storage and have synthesized a series of microcapsule samples through in-situ polycondensation in a non-aqueous emulsion templating system. The scanning electron microscopic investigation indicated that the resultant microcapsules presented the regular spheres with a smooth surface and a uniform size distribution, while the transmission electron microscopy showed a well-defined core–shell structure for these microcapsules. The Fourier–transform infrared spectroscopy characterized the chemical compositions of the resultant microcapsules, and the rare-earth elements doped within the zirconia shell were confirmed by energy-dispersive X-ray patterns and X–ray photoelectron spectroscopy. The resultant microcapsules exhibited a good thermal regulation capability with high encapsulation and energy-storage efficiencies. Most of all, the photoluminescence characterization indicated that these rare-earth-doped microcapsules achieved a significant enhancement in emission intensity of the cyan-colored up-conversion and purple-colored down-conversion fluorescence after excited by radiation at wavelengths of 850 and 280 nm, respectively. The enhancement level of emission intensity varied with different rare-earth species and was determined by the bond length of rare-earth ion to oxygen in the solid solution of zirconia host.

Controllable synthesis of niobium doped mesoporous silica materials with various morphologies and its activity for oxidative catalysis

Nb doped HMS-X (Nb-HMS-X) was synthesized by sol–gel/emulsion method using non-ionic tri-block copolymer surfactant PEO140PPO39PEO140 (P123) as a structure directing agent. The effect of synthesis condition on the pore morphology and nature of pore ordering was investigated. Small-angle X-ray Scattering (SAXS) revealed highly ordered pore structure in Nb-HMS-X. It is demonstrated by Field Emission Scanning Electron Microscopy (FESEM) that the materials possessed various morphologies such as, regular spheres, disordered and tube-spheres depending on synthesis conditions. The solid state 29Si nuclear magnetic resonance measurements showed that chemical environment of silicon atoms get modified significantly with synthesis condition. Furthermore, the synthesized niobium doped hollow mesoporous silica (Nb-HMS-X) was effective to catalyze ethyl benzene oxidation reaction where activation of C–H bond took place.

Fabrication of multifunctional microcapsules containing n-eicosane core and zinc oxide shell for low-temperature energy storage, photocatalysis, and antibiosis

In this study, a novel type of multifunctional microcapsules based on an n-eicosane phase change material (PCM) core and a ZnO shell were designed not only for latent heat storage but also for photocatalytic and antibacterial activities. A series of microcapsule samples were synthesized through an in-situ precipitation reaction of Zn(CH3COO)2⋅2H2O and NaOH in an O/W emulsion templating system followed by a long-term aging process. The formation of the ZnO shell was monitored by X-ray powder diffraction to identify a phase transition from ε-Zn(OH)2 to ZnO. The chemical composition and surface elemental distribution of the resultant microcapsules were characterized by Fourier-transform infrared, energy-dispersive X-ray, and X-ray photoelectron spectroscopy. Morphologic investigation demonstrated that the microcapsules presented regular spheres with a well-defined core–shell structure. Differential scanning calorimetry analysis indicated that the phase change performance and encapsulation efficiency of the microcapsules were determined by the weight ratio of n-eicosane/Zn(CH3COO)2⋅2H2O loaded in the synthesis. Moreover, the microcapsules achieved an excellent energy storage capability and a high working reliability. Most of all, the multifunctional microcapsules gained high photocatalytic and antibacterial activities and especially revealed a high antimicrobial effectiveness against Staphylococcus aureus. With such a multifunctional feature, the microcapsules developed in this work highlight their potential applications in environmental protection and biomedical fields.

Synthesis and electrochemical properties of Li1.2Mn0.54Ni0.13Co0.13O2 cathode material for lithium-ion battery

The layered Li1.2Mn0.54Ni0.13Co0.13O2 lithium-rich manganese-based solid solution cathode material has been synthesized by a simple solid-state method. The as-prepared material has a typical layered structure with R-3m and C2/m space group. The synthesized Li1.2Mn0.54Ni0.13Co0.13O2 has an irregular shape with the size range from 200 to 500 nm, and the primary particle of Li1.2Mn0.54Ni0.13Co0.13O2 has regular sphere morphology with a diameter of 320 nm. Electrochemical performances also have been investigated. The results show that the cathode material Li1.2Mn0.54Ni0.13Co0.13O2 prepared at 900 °C for 12 h has a good electrochemical performance, which can deliver a high initial discharge capacity of 233.5, 214.2, 199.3, and 168.1 mAh g−1 at 0.1, 0.2, 0.5, and 1 C, respectively. After 50 cycles, the capacity retains 178.0, 166.3, 162.1, and 155.9 mAh g−1 at 0.1, 0.2, 0.5, and 1 C, respectively. The results indicate that the simple method has a great potential in synthesizing manganese-based cathode materials for Li-ion batteries.

Abstract 118: EGFL6, a potential novel ligand of EGFR, play roles in Nasopharyngeal cacinoma metastasis through establishing invasive and long-distant metastatic niche by paracrine and autocrine

Abstract Distant metastasis is the leading cause of treatment failure in Nasopharyngeal carcinoma (NPC). Our study focused on the searching of potential targets for NPC metastasis treatment. cDNA microarray was applied in this screening. We compared gene expression level in metastatic NPC, non-metastatic NPC and inflammatory cases with different bioinformatic methods. EGFL6 was chosen for further study. The over-expression of EGFL6 was confirmed in NPC cell lines and 63% of the metastatic cases(n = 7/11, 3 years follow-up) by Q-PCR. EGFL6 was identified as an independent prognostic index for NPC distant metastasis survival prognostic, P = 0.023 (n = 96, QPCR). As a follicle stem cell specifically expressed secretion protein, EGFL6 showed its powerful strength in promoting cell migration and especially the formation of aggressive morphology in the matrix-gel based three-dimensional culture. With the overexpression of secreting EGFL6, CNE2 cells formed the follicle-like structure but with more aggressive leading edge, which invaded deep into the matrix-gel instead of forming single layer epithelial structure. EGFL6 overexpressed SUNE1 cells breakthrough the restriction of its regular sphere structure, and migrated for more spaces. In vivo study also showed that EGFL6 dramatically increased the tumorigenisis in subcutaneous injection assay and the growth of metastatic tumor in the mice tail vein injection experiment. Mechanism study showed that EGFL6 was a potential novel ligand of EGFR. Our resulted demonstrated that EGFL6 could bind to EGFR and caused its phosphorylation, which activated EGFR and leaded to its internalization. c-Src was subsequently phosphorylated, and the MAPK/ERK signalling cascade was activated. The EGFL6 bound cells down-regulated their expression of E-cadherin and loosed the connection with the adjacent cells, strength their F-actin and vimentin towards the direction they migrated, which indicated a transition from epithelial to mesenchymal characteristic. Further study is on going to investigate the potential of EGFL6 as a therapeutic target for NPC metastatic treatment. In conclusion, we found that EGFL6 was a potential novel ligand of EGFR, which played roles in NPC metastasis through establishing invasive and long-distant metastatic cancer niche by paracrine and autocrine. Citation Format: Jinna Chen, Chen Jiang, Jing Yang, Ya-hui Yu, Lei Li, Yang-qun Xiang, Xinyuan Guan. EGFL6, a potential novel ligand of EGFR, play roles in Nasopharyngeal cacinoma metastasis through establishing invasive and long-distant metastatic niche by paracrine and autocrine. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 118. doi:10.1158/1538-7445.AM2015-118

Plastic deformation and compressive mechanical properties of hollow sphere aluminum foams produced by space holder technique

Abstract In this study, experimental procedure and numerical methods were utilized to evaluate the effect of regular and irregular pore distribution as well as loading direction on compressive properties and deformation mechanism of hollow sphere aluminum foams. In order to study scaling laws, different volume fractions of the regular samples were produced and loaded in horizontal and vertical directions to address the loading conditions effects. For this purpose, expanded polystyrene (EPS) grains were expanded to a designed diameter size and positioned in different configurations. Compression test results showed higher elastic properties for irregular sample due to the thicker cell walls while energy absorption capability at high strains was found to be reduced due to the non-uniform deformation in comparison with regular foams. In regular samples, a nonlinear behavior in the elastic regime was observed since the imperfections during casting procedure. Furthermore, similar deformation mechanisms were found for the set of samples with similar pore configurations indicating the feasibility of controlling deformation mechanism by manipulating morphological characteristics. Finite element results well predicted deformation mechanism of structures and plastic properties of regular hollow sphere samples especially for plateau stress with less than 12% relative error.

The Effect of the Shape of Granular Particles on Density

We investigate the packing densities of non-elongated regular polyhedra and spheres via discrete element simulations. It turns out that the limit of many (hundred) corners does not correspond to that of spheres with the same Young’s modulus. However, if the Young’s modulus is simultaneously decreased, the packing density of polyhedra approaches that of (harder) spheres. We conclude that the mechanism for the higher packing density is the higher mobility of particles, in the case of round particles due to rolling. While rolling can occur at vanishing energetic costs for perfect spheres, the mobility of polyhedra in packings is determined by the height differences between corners and faces, as well as due to the possibility that corners of neighbouring polyhedra to move through each other via deformation: reducing material strength therefore improves mobility. Additionally, we present finding about the influence of the walls and about the relation between filling height and surface roughness.

A note on Ribaucour transformations in Lie sphere geometry

Following Burstall and Hertrich-Jeromin we study the Ribaucour transformation of Legendre submanifolds in Lie sphere geometry. We give an explicit parametrization of the resulted Legendre submanifold $\hat{F}$ of a Ribaucour transformation, via a single real function $\tau$ which represents the regular Ribaucour sphere congruence $s$ enveloped by the original Legendre submanifold $F$.

Simulations of two sedimenting-interacting spheres with different sizes and initial configurations using immersed boundary method

Numerical investigations are carried out for the drafting, kissing and tumbling (DKT) phenomenon of two freely falling spheres within a long container by using an immersed-boundary method. The method is first validated with flows induced by a sphere settling under gravity in a small container for which experimental data are available. The hydrodynamic interactions of two spheres are then studied with different sizes and initial configurations. When a regular sphere is placed below the larger one, the duration of kissing decreases in pace with the increase in diameter ratio. On the other hand, the time duration of the kissing stage increases in tandem with the increase in diameter ratio as the large sphere is placed below the regular one, and there is no DKT interactions beyond threshold diameter ratio. Also, the gap between homogeneous spheres remains constant at the terminal velocity, whereas the gaps between the inhomogeneous spheres increase due to the differential terminal velocity.

One- and two-dimensional polymers from proline and calcium bromide.

Reactions of calcium bromide with enantiopure and racemic proline in aqueous solution lead to two solids in which the zwitterionic amino acid acts as a bridging ligand between neighbouring cations. Depending on the chirality of the amino acid, topologically very different products are obtained. With racemic proline, bromide acts as a simple uncoordinated counter-anion for the cationic heterochiral chains in catena-poly[[aquacalcium(II)]-μ-aqua-μ3-DL-proline-μ2-DL-proline], {[Ca(C5H9NO2)2(H2O)2]Br2}n. In agreement with chemical intuition, only carboxylate and aqua O atoms coordinate the alkaline earth cation in a low-symmetry arrangement. In contrast, L-proline affords the two-dimensional network poly[dibromidobis(μ2-L-proline)calcium(II)], [CaBr2(C5H9NO2)2]n, with an unexpected CaBr2 unit in a more regular coordination sphere.

An Analysis and Design of the Preparation Orbit for the Lunar Satellite

On the basis of the moon as regular sphere approximately, establish fixed coordinate system of the moon, In the condition of the least energy consumption, collecting information furthest, landing on the landing point precisely and so on, found the astronomy model which is based on geometric area. Meanwhile, combined with the direction and cycle of the moon's Autobiography, as well as the formula of universal gravitation etc, analyze and design the preparation orbit, then work out the related parameters.

Application of Computational Fluid Dynamics (CFD) for the Evaluation of Fluid Convective Radial Heat Transfer Parameters in Packed Beds

A model to simulate the behavior of multitubular packed-bed catalytic reactors was recently proposed [Asensio, D. A.; Zambon, M. T.; Mazza, G. D.; Barreto, G. F. Ind. Eng. Chem. Res. 2014, 53, 3587–3605]. In particular, the model introduces a heat transfer coefficient hwf that accounts for an unmixed fluid film on the wall and a coefficient hf between the fluid channels at a distance Dp/2 from the wall. Computational fluid dynamics simulations intended to evaluate these parameters are described. Four regular sphere arrays between parallel planes that provide different combinations of wall and core channel voidages (ε1 and εc) were employed. Reynolds and Prandtl numbers ranges were 100 < Rep < 2000 and 0.4 < Pr < 3.5. Calculated values of hwf and hf are well correlated with those of ε1, εc, Rep, and Pr. Results for ε1 and εc values typical of randomly packed beds of low ratio Dt/Dp show good agreement with carefully analyzed data from the literature.

Computational image analysis of colony and nuclear morphology to evaluate human induced pluripotent stem cells.

Non-invasive evaluation of cell reprogramming by advanced image analysis is required to maintain the quality of cells intended for regenerative medicine. Here, we constructed living and unlabelled colony image libraries of various human induced pluripotent stem cell (iPSC) lines for supervised machine learning pattern recognition to accurately distinguish bona fide iPSCs from improperly reprogrammed cells. Furthermore, we found that image features for efficient discrimination reside in cellular components. In fact, extensive analysis of nuclear morphologies revealed dynamic and characteristic signatures, including the linear form of the promyelocytic leukaemia (PML)-defined structure in iPSCs, which was reversed to a regular sphere upon differentiation. Our data revealed that iPSCs have a markedly different overall nuclear architecture that may contribute to highly accurate discrimination based on the cell reprogramming status.

Coarse- and fine-grid numerical behavior of MRT/TRT lattice-Boltzmann schemes in regular and random sphere packings

We analyze the intrinsic impact of free-tunable combinations of the relaxation rates controlling viscosity-independent accuracy of the multiple-relaxation-times (MRT) lattice-Boltzmann models. Preserving all MRT degrees of freedom, we formulate the parametrization conditions which enable the MRT schemes to provide viscosity-independent truncation errors for steady state solutions, and support them with the second- and third-order accurate (“linear” and “parabolic”, respectively) boundary schemes. The parabolic schemes demonstrate the advanced accuracy with weak dependency on the relaxation rates, as confirmed by the simulations with the D3Q15 model in three regular arrays (SC, BCC, FCC) of touching spheres. Yet, the low-order, bounce-back boundary rule remains appealing for pore-scale simulations where the precise distance to the boundaries is undetermined. However, the effective accuracy of the bounce-back crucially depends on the free-tunable combinations of the relaxation rates. We find that the combinations of the kinematic viscosity rate with the available “ghost” antisymmetric collision mode rates mainly impact the accuracy of the bounce-back scheme. As the first step, we reduce them to the one combination (presented by so-called “magic” parameter Λ in the frame of the two-relaxation-times (TRT) model), and study its impact on the accuracy of the drag force/permeability computations with the D3Q19 velocity set in two different, dense, random packings of 8000 spheres each. We also run the simulations in the regular (BCC and FCC) packings of the same porosity for the broad range of the discretization resolutions, ranging from 5 to 750 lattice nodes per sphere diameter. A special attention is given to the discretization procedure resulting in significantly reduced scatter of the data obtained at low resolutions. The results reveal the identical Λ-dependency versus the discretization resolution in all four packings, regular and random. While very small Λ values overestimate the drag measurements several-fold on the coarse grids, Λ>1 may overestimate the permeability at the same extent. In low resolution region we provide practical guidelines, extending previously known solutions for the straight/diagonal Poiseuille flow. Analysis of the high-resolution region reveals the collapse of the solutions obtained with all the considered Λ values with the average rate of −1.3, followed by their common, smooth, first-order convergence with the rate of −1.0 as the best, towards the reference solutions provided by the “parabolic” schemes. High-quality power-law fits estimate that the bounce-back would reach their accuracy (obtained at about 200 nodes per sphere) for two-order magnitude higher grid resolution.

Facile fabrication of carbon spheres with tunable morphologies from novel polymeric carbon precursors.

This study presents a facile and general method for fabrication of carbon spheres with tunable morphologies based on the sol-gel reaction of a novel polymeric carbon precursor. The carbon precursor was fabricated by the synthesis of resole, a low-molecular weight polymer of phenol and formaldehyde, and then the modification with poly(ethylene glycol) monomethyl ether (PEG). By turning the modification degree of resole with different amounts of PEG and the hydrolysis and condensation reactions of this precursor, carbon spheres with various morphologies, including regular spheres, hollow spheres of different pore sizes, and raspberry- and peanut-like spheres, were produced easily. This should be attributed to the condensation, self-assembly, and phase separation of the new polymeric carbon precursors during the sol-gel process.

Emulsion stability and cross-linking of PMMA microcapsules containing phase change materials

The microencapsulation of paraffin as a phase change material (PCM) using poly methyl methacrylate (PMM) as a shell was investigated by means of suspension polymerization. The increase in the emulsion stability by using mixed surfactants was studied. It was observed that a mixed surfactants system induces long-term emulsion stability and monodisperse droplets size distribution. Also, the use of mixed surfactants reduces significantly the buckles in microcapsules significantly. The effect of using pentaerythritol tetraacrylate (PETRA) as a cross-linker agent on the diverse properties of PCM microcapsules such as morphology, energy storage density, shell permeability and thermal stability has been investigated. Adding PETRA to the system improves the surface morphology and produces microcapsules with a much higher PCM content. For example, the core/shell mass ratio of 2:1 produces microcapsules with regular spheres having smooth surfaces. TGA results show two steps thermal degradation of microcapsules. The mass loss was similar to the non-encapsulated PCM until all the PCM was dissipated (step 1). Following that the microcapsules experienced lower rate of mass loss of the shell, which depends on its thickness (step 2).

Synthesis, characterization and catalytic activity of nano-spherical MCM-41 modified with vanadium.

Vanadium modified MCM-41 nanospheres were synthesized by the impregnation and sol-gel super-molecular method respectively. Structure and morphology of the obtained materials were characterized using X-ray diffraction (XRD), inductively coupling plasma (ICP), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and N2-adsorption-desorption techniques. The influence of particle sizes on their catalytic activities in styrene oxidation and benzene hydroxylation was investigated. Results revealed that all the samples had regular sphere shape and adjustable particle size within 40-160 nm, and exhibited high catalytic activities in the oxidation of styrene and hydroxylation of benzene. The smaller the particle size is, the higher the activity becomes. Meanwhile, the catalysts synthesized by the sol-gel method are more effective than that synthesized via impregnation method, indicating the vanadium species in the mesoporous framework are probably the catalytic active sites.

Submicron-Lubricant Based on Crystallized Fe3O4 Spheres for Enhanced Tribology Performance

We demonstrate in this paper a novel finding of submicron-lubricant exemplified by crystallized magnetite (Fe3O4) submicrometer spheres. Optimized tribological performance of lubricant particles occurs when the particles are submicrometer sized and spherical. The tribology of lubricant particles is thus verified to be size and shape dependent. Owing to the unique heating and quenching process involved in pulsed laser irradiation, Fe3O4 submicrometer spheres are acquired through phase transformation and reshaping. The formation process of the regular Fe3O4 spheres in deionized water was investigated by choosing different laser fluences and irradiation times. The shape and phase transformation mechanisms are elucidated as well. Tribological properties of the obtained Fe3O4 submicrometer spheres have been explored, inspired by their spherical shape and smooth surfaces. Crystallized magnetite submicrometer spheres under optimized conditions show a reduction in friction and wear by up to 40% and 20%, respectiv...

Microstructure-based calculations and experimental results for sound absorbing porous layers of randomly packed rigid spherical beads

Acoustics of stiff porous media with open porosity can be very effectively modelled using the so-called Johnson-Champoux-Allard-Pride-Lafarge model for sound absorbing porous media with rigid frame. It is an advanced semi-phenomenological model with eight parameters, namely, the total porosity, the viscous permeability and its thermal analogue, the tortuosity, two characteristic lengths (one specific for viscous forces, the other for thermal effects), and finally, viscous and thermal tortuosities at the frequency limit of 0 Hz. Most of these parameters can be measured directly, however, to this end specific equipment is required different for various parameters. Moreover, some parameters are difficult to determine. This is one of several reasons for the so-called multiscale approach, where the parameters are computed from specific finite-element analyses based on some realistic geometric representations of the actual microstructure of porous material. Such approach is presented and validated for layers made up of loosely packed small identical rigid spheres. The sound absorption of such layers was measured experimentally in the impedance tube using the so-called two-microphone transfer function method. The layers are characterised by open porosity and semi-regular microstructure: the identical spheres are loosely packed by random pouring and mixing under the gravity force inside the impedance tubes of various size. Therefore, the regular sphere packings were used to generate Representative Volume Elements suitable for calculations at the micro-scale level. These packings involve only one, two, or four spheres so that the three-dimensional finite-element calculations specific for viscous, thermal, and tortuous effects are feasible. In the proposed geometric packings, the spheres were slightly shifted in order to achieve the correct value of total porosity which was precisely estimated for the layers tested experimentally. Finally, in this paper some results based on the self-consistent estimates are also provided.