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Particle size+ effect

Lei Li, Feijun Wang, Ziqiang Shao
A biomass-based magnetic fluorescent nanoparticle (MFNPs) was successively in situ synthesized via a one-step high-gravity approach, which constructed by a magnetic core of Fe3O4 nanoparticles, the fluorescent marker of carbon dots (CDs), and shells of chitosan (CS). The obtained MFNPs had a 10 nm average diameter and narrow particle size distribution, low cytotoxicity, superior fluorescent emission and superparamagnetic properties. The encapsulating and release 5-fluorouracil experiments confirmed that the introduction of CS/CDs effectively improved the drug loading capacity...
March 15, 2018: Carbohydrate Polymers
Hui-Ju Yen, Yen-An Young, Tsung-Neng Tsai, Kuang-Ming Cheng, Xin-An Chen, Ying-Chuan Chen, Cheng-Cheung Chen, Jenn-Jong Young, Po-da Hong
In this study, we synthesized various quaternary chitosan derivatives and used them to stabilize gold nanoparticles (AuNPs). These chitosan derivatives comprised N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride (HTCC), folate-HTCC, galactosyl-HTCC, and their fluorescein isothiocyanate-conjugated derivatives. Various positively surface-charged AuNPs were prepared under alkaline conditions using glucose as a reducing agent in the presence of the HTCC derivatives (HTCCs). The effects of the concentration of NaOH, glucose, and HTCCs on the particles size, zeta potential, and stability were studied in detail...
March 1, 2018: Carbohydrate Polymers
Aleksandar Donev, Chiao-Yu Yang, Changho Kim
We develop a Split Reactive Brownian Dynamics (SRBD) algorithm for particle simulations of reaction-diffusion systems based on the Doi or volume reactivity model, in which pairs of particles react with a specified Poisson rate if they are closer than a chosen reactive distance. In our Doi model, we ensure that the microscopic reaction rules for various association and dissociation reactions are consistent with detailed balance (time reversibility) at thermodynamic equilibrium. The SRBD algorithm uses Strang splitting in time to separate reaction and diffusion and solves both the diffusion-only and reaction-only subproblems exactly, even at high packing densities...
January 21, 2018: Journal of Chemical Physics
Shari P Finner, Mihail I Kotsev, Mark A Miller, Paul van der Schoot
We investigate percolation in mixtures of nanorods in the presence of external fields that align or disalign the particles with the field axis. Such conditions are found in the formulation and processing of nanocomposites, where the field may be electric, magnetic, or due to elongational flow. Our focus is on the effect of length polydispersity, which-in the absence of a field-is known to produce a percolation threshold that scales with the inverse weight average of the particle length. Using a model of non-interacting spherocylinders in conjunction with connectedness percolation theory, we show that a quadrupolar field always increases the percolation threshold and that the universal scaling with the inverse weight average no longer holds if the field couples to the particle length...
January 21, 2018: Journal of Chemical Physics
Jinling Wang, Ying Li, Lifang Wang, Xiaohui Wang, Pengfei Tu
Polyethylene glycol (PEG)-based block copolymer micelles and hyaluronic acid (HA)-based grafted copolymer micelles have been widely investigated in chemotherapy. In this study, to evaluate the differences among HA-based grafted polymer micelles, PEG-based block polymer micelles and the mixed of these two micelles in enhancing antitumor effects and overcoming MDR, two amphiphilic vitamin E succinate (VES) derivatives, HA VES (HA-g-VES) and PEG 2000 VES (TPGS2k), were applied as nanocarriers to prepare HA-VES micelles (HA-PMs), TPGS2k micelles (TPGS2k-PMs) and the mixed micelles (HA/TPGS2k-PMs) for the co-delivery of doxorubicin (DOX) and curcumin (Cur)...
November 2018: Drug Delivery
Luca Ferrero, Marco Casati, Lara Nobili, Luca D'Angelo, Grazia Rovelli, Giorgia Sangiorgi, Cristiana Rizzi, Maria Grazia Perrone, Antonio Sansonetti, Claudia Conti, Ezio Bolzacchini, Elena Bernardi, Ivano Vassura
The collection of atmospheric particles on not-filtering substrates via dry deposition, and the subsequent study of the particle-induced material decay, is trivial due to the high number of variables simultaneously acting on the investigated surface. This work reports seasonally resolved data of chemical composition and size distribution of particulate matter deposed on stone and surrogate surfaces obtained using a new method, especially developed at this purpose. A "Deposition Box" was designed allowing the particulate matter dry deposition to occur selectively removing, at the same time, variables that can mask the effect of airborne particles on material decay...
January 19, 2018: Environmental Science and Pollution Research International
Linzhu Wang, Junqi Li, Shufeng Yang, Chaoyi Chen, Huixin Jin, Xiang Li
Tremendous focus has been put on the control of particle size distribution which effects the grain structure and mechanical properties of resulting metallic materials, and thus nucleation and growth of particles in solution should be clarified. This study uses classical nucleation theory and Ostwald ripening theory to probe the relationship between the compositions of Fe-O-Al-Ca melts and the behavior of particles under the condition of no external stirring. Our experimental data suggest that decreasing the initial Ca addition and Al addition is conductive to the increase of nucleation rate for calcium aluminate particles, which exhibits a same change trend with that predicted from classical nucleation theory...
January 18, 2018: Scientific Reports
Kyungtae Kim, Akash Arora, Ronald M Lewis, Meijiao Liu, Weihua Li, An-Chang Shi, Kevin D Dorfman, Frank S Bates
Cooling disordered compositionally asymmetric diblock copolymers leads to the formation of nearly spherical particles, each containing hundreds of molecules, which crystallize upon cooling below the order-disorder transition temperature (TODT). Self-consistent field theory (SCFT) reveals that dispersity in the block degrees of polymerization stabilizes various Frank-Kasper phases, including the C14 and C15 Laves phases, which have been accessed experimentally in low-molar-mass poly(isoprene)-b-poly(lactide) (PI-PLA) diblock copolymers using thermal processing strategies...
January 18, 2018: Proceedings of the National Academy of Sciences of the United States of America
Hongfei Liu, Hui Ding, Dandan Zhang, - Fengsi, Changshan Sun
The main objective of this study was to prepare the levodopa/carbidopa compound drug resins and investigate affecting factors such as drug concentration, temperature, particle size. The drug resins were made by bath method and the effects of above factors during the process of preparation was studied. Studies on the stabilities of drugs and drug resins were carried out by HPLC. The Results showed that the preparation of drug resins was influenced by drug concentration, resin particle size, reaction temperature and solvent concentration...
January 2018: Pakistan Journal of Pharmaceutical Sciences
Shahram Emami, Mohammadreza Siahi-Shadbad, Mohammad Barzegar-Jalali, Khosro Adibkia
OBJECTIVES: This study employed electrospray deposition (ESD) for simultaneous synthesis and particle engineering of cocrystals. SIGNIFICANCE: Exploring new methods for the efficient production of cocrystals with desired particle properties is an essential demand. METHODS: The possibility of cocrystal formation by ESD was examined for indomethacin-saccharin, indomethacin-nicotinamide, naproxen-nicotinamide, and naproxen-iso-nicotinamide cocrystals...
January 18, 2018: Drug Development and Industrial Pharmacy
Jaleh Varshosaz, Erfaneh Ghassami, Abdollah Noorbakhsh, Ali Jahanian-Najafabadi, Mohsen Minaiyan, Ramezan Behzadi
OBJECTIVES: Ovarian cancer is still a major cause of morbidity and mortality. Docetaxel (DTX) is one of the most notable cytotoxic agents for treatment of ovarian cancer. However, its side-effects proposed considerable problems to the patients. SIGNIFICANCE: Polymeric nanoparticles (NPs) of poly (butylene adipate-co-butylene terephthalate) (Ecoflex®), a biodegradable and biocompatible polymer, were prepared for the first time by the upgradeable electrospraying technique...
January 18, 2018: Drug Development and Industrial Pharmacy
Elsen Tjhung, Ludovic Berthier
Tracking experiments in dense biological tissues reveal a diversity of sources for local energy injection at the cell scale. The effect of cell motility has been largely studied, but much less is known about the effect of the observed volume fluctuations of individual cells. We consider a microscopic model of "actively deforming" particles where local fluctuations of the particle size constitute a unique source of motion. We demonstrate that collective motion can emerge under the sole influence of such active volume fluctuations...
November 2017: Physical Review. E
Anna Yu Solovyova, Ekaterina A Elfimova, Alexey O Ivanov, Philip J Camp
The effects of particle-size polydispersity on the magnetostatic properties of concentrated ferrofluids are studied using theory and computer simulation. The second-order modified mean-field (MMF2) theory of Ivanov and Kuznetsova [Phys. Rev. E 64, 041405 (2001)1063-651X10.1103/PhysRevE.64.041405] has been extended by calculating additional terms of higher order in the dipolar coupling constant in the expansions of the initial magnetic susceptibility and the magnetization curve. The theoretical predictions have been tested rigorously against results from Monte Carlo simulations of model monodisperse, bidisperse, and highly polydisperse ferrofluids...
November 2017: Physical Review. E
Martin Girard, Trung Dac Nguyen, Monica Olvera de la Cruz
Coarse-grained potentials are ubiquitous in mesoscale simulations. While various methods to compute effective interactions for spherically symmetric particles exist, anisotropic interactions are seldom used, due to their complexity. Here we describe a general formulation, based on a spatial decomposition of the density fields around the particles, akin to atomic orbitals. We show that anisotropic potentials can be efficiently computed in numerical simulations using Fourier-based methods. We validate the field formulation and characterize its computational efficiency with a system of colloids that have Gaussian surface charge distributions...
November 2017: Physical Review. E
C R K Windows-Yule, D L Blackmore, A D Rosato
The decay of energy within particulate media subjected to an impulse is an issue of significant scientific interest, but also one with numerous important practical applications. In this paper, we study the dynamics of a granular system exposed to energetic impulses in the form of discrete taps from a solid surface. By considering a one-dimensional toy system, we develop a simple theory, which successfully describes the energy decay within the system following exposure to an impulse. We then extend this theory so as to make it applicable also to more realistic, three-dimensional granular systems, assessing the validity of the model through direct comparison with discrete particle method simulations...
October 2017: Physical Review. E
Zhenjiu Wang, Fakher F Assaad, Francesco Parisen Toldin
We introduce a quantum Monte Carlo method at finite temperature for interacting fermionic models in the canonical ensemble, where the conservation of the particle number is enforced. Although general thermodynamic arguments ensure the equivalence of the canonical and the grand-canonical ensembles in the thermodynamic limit, their approach to the infinite-volume limit is distinctively different. Observables computed in the canonical ensemble generically display a finite-size correction proportional to the inverse volume, whereas in the grand-canonical ensemble the approach is exponential in the ratio of the linear size over the correlation length...
October 2017: Physical Review. E
Nicolas Estrada, W F Oquendo
This article presents a numerical study of the effects of grain size distribution (GSD) on the microstructure of two-dimensional packings of frictionless disks. The GSD is described by a power law with two parameters controlling the size span and the shape of the distribution. First, several samples are built for each combination of these parameters. Then, by means of contact dynamics simulations, the samples are densified in oedometric conditions and sheared in a simple shear configuration. The microstructure is analyzed in terms of packing fraction, local ordering, connectivity, and force transmission properties...
October 2017: Physical Review. E
Alan R Denton
Interparticle interactions and bulk properties of colloidal suspensions can be substantially modified by the addition of nanoparticles. Extreme asymmetries in size and charge between colloidal particles and nanoparticles present severe computational challenges to molecular-scale modeling of such complex systems. We present a statistical mechanical theory of effective electrostatic interactions that can greatly ease large-scale modeling of charged colloid-nanoparticle mixtures. By applying a sequential coarse-graining procedure, we show that a multicomponent mixture of charged colloids, nanoparticles, counterions, and coions can be mapped first onto a binary mixture of colloids and nanoparticles and then onto a one-component model of colloids alone...
December 2017: Physical Review. E
Jean-François Camenen, Yannick Descantes
Three-dimensional discrete numerical simulation is used to investigate the properties of close-packed frictionless granular assemblies as a function of particle polydispersity and shape. Unlike some experimental results, simulations show that disordered packings of pinacoids (eight-face convex polyhedra) achieve higher solid fraction values than amorphous packings of spherical or rounded particles, thus fulfilling the analog of Ulam's conjecture stated by Jiao and co-workers for random packings [Y. Jiao and S...
July 2017: Physical Review. E
Monica E A Zakhari, Patrick D Anderson, Markus Hütter
Open-porous deformable particles, often envisaged as sponges, are ubiquitous in biological and industrial systems (e.g., casein micelles in dairy products and microgels in cosmetics). The rich behavior of these suspensions is owing to the elasticity of the supporting network of the particle, and the viscosity of permeating solvent. Therefore, the rate-dependent size change of these particles depends on their structure, i.e., the permeability. This work aims at investigating the effect of the particle-size dynamics and the underlying particle structure, i...
July 2017: Physical Review. E
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