Hydrodynamic Surface Research Articles

Alginate stabilized gold nanoparticle as multidrug carrier: Evaluation of cellular interactions and hemolytic potential

This work delineates the synthesis of curcumin (Ccm) and methotrexate (MTX) conjugated biopolymer stabilized AuNPs (MP@Alg–Ccm AuNPs). The dual drug conjugated nano-vector was characterized by FTIR, 1H NMR and UV–vis spectroscopic techniques. Hydrodynamic diameter and surface charge of the AuNPs were determined by DLS analysis and the spherical particles were visualized by TEM. MP@Alg–Ccm AuNPs exhibited improved cytotoxic potential against C6 glioma and MCF-7 cancer cell lines and was found to be highly hemocompatible. MP@Alg–Ccm AuNPs also exhibited active targeting efficiency against MCF-7 cancer cells due to the presence of “antifolate” drug MTX. Thus MP@Alg–Ccm AuNPs may find potential application in targeted combination chemotherapy for the treatment of cancer. The study is also interesting from the synthetic point of view because, here generation of AuNPs was done using “green chemical” alginate and dual drug conjugated AuNPs were created in two simple reaction steps using “green solvent” water.

Characterization of refined papermaking pulps using hydrodynamic parameters from filtration analysis

It is often necessary to characterize papermaking pulps in order to determine the impact of refining or to predict their drainage properties. The newer methods for pulp quality analysis determine geometrical features of pulp fibers by microimaging techniques. However, features such as fiber length, coarsenes, and their distributions do not yield easily to estimation of their drainage or papermaking properties. In quantifying the impact of refining on fiber quality, it is useful to approach the rheology of pulps as an indicator of their behavior. We determined the hydrodynamic characteristics of a variety of refined pulps along with their permeability characteristics, i.e., the hydrodynamic specific surface area and the specific volume. Our method was to analyze the filtration/drainage curves and fit predictions from models with observed data. This inversion problem is usually complex and requires global minimization techniques. This paper presents data on bleached kraft hardwood pulps and mixtures with fines and how their surface areas and specific volumes change with composition. These data are further used to predict the behavior of the pulps in drainage situations using models of forming.

Whole-animal imaging and flow cytometric techniques for analysis of antigen-specific CD8+ T cell responses after nanoparticle vaccination.

Traditional vaccine adjuvants, such as alum, elicit suboptimal CD8+ T cell responses. To address this major challenge in vaccine development, various nanoparticle systems have been engineered to mimic features of pathogens to improve antigen delivery to draining lymph nodes and increase antigen uptake by antigen-presenting cells, leading to new vaccine formulations optimized for induction of antigen-specific CD8+ T cell responses. In this article, we describe the synthesis of a "pathogen-mimicking" nanoparticle system, termed interbilayer-crosslinked multilamellar vesicles (ICMVs) that can serve as an effective vaccine carrier for co-delivery of subunit antigens and immunostimulatory agents and elicitation of potent cytotoxic CD8+ T lymphocyte (CTL) responses. We describe methods for characterizing hydrodynamic size and surface charge of vaccine nanoparticles with dynamic light scattering and zeta potential analyzer and present a confocal microscopy-based procedure to analyze nanoparticle-mediated antigen delivery to draining lymph nodes. Furthermore, we show a new bioluminescence whole-animal imaging technique utilizing adoptive transfer of luciferase-expressing, antigen-specific CD8+ T cells into recipient mice, followed by nanoparticle vaccination, which permits non-invasive interrogation of expansion and trafficking patterns of CTLs in real time. We also describe tetramer staining and flow cytometric analysis of peripheral blood mononuclear cells for longitudinal quantification of endogenous T cell responses in mice vaccinated with nanoparticles.

Effects of water quality parameters on agglomeration and dissolution of copper oxide nanoparticles (CuO-NPs) using a central composite circumscribed design

Once released into the aquatic environment, nanoparticles (NPs) are expected to interact (e.g., dissolve, agglomerate, settle), with important consequences for particle fate and toxicity. However, a clear understanding of how environmental factors influence the toxicity and fate of NPs in the environment is still in its infancy. In this study, a second order central composite circumscribed design (CCCD) was employed to systematically explore how different combinations of pH, hardness, and natural organic matter (NOM) in receiving water affect the hydrodynamic diameter, surface charge (zeta potential), and release of free Cu2+ from CuO-NPs under a range of environmentally realistic conditions. The results clearly showed that all three CuO-NP properties varied markedly as functions of pH, hardness and dissolved NOM, confirming that agglomeration and the extent of release of free Cu2+ largely depend on the surrounding environmental conditions. The response of hydrodynamic diameter, but not zeta potential, to water quality parameters was highly time dependent, showing very different patterns on day 2 and day 10. The approach used in this study can contribute to improving understanding of how, and to what extent, environmental factors affect the physicochemical properties of CuO-NPs once they enter aquatic environments. This understanding can help to predict the conditions under which CuO-NPs are likely to become problematic, which can inform management and mitigation actions.

Effect of Functional Group and Surface Charge of PEG and Dextran-Coated USPIO as a Contrast Agent in MRI on Relaxivity Constant

The challenges in molecular imaging are focused on the development of novel contrast agents with much lower relaxation times. Ultrasmall superparamagnetic iron oxide nanoparticles known as USPIO have been used for a variety of applications such as imaging of cancer, apoptosis, and hyperthermia providing higher signal changes based on $$T_{2}^{*}$$ weighted susceptibility effects. Although many studies had been performed on USPIO there is still a lack of data on the effects of the physicochemical properties of these nanoparticles (NP) such as hydrodynamic size, surface charge and type of functional groups, which may alter the relaxivity of these NPs. The aim of this study was to evaluate the effect of different functional groups and surface charges of PEGylated and dextran-coated NPs on their magnetic properties. All relaxometry studies were performed using a 3-T magnetic resonance imaging. Our results showed that the impact of charge on magnetic properties is much higher than that of coating thickness. In this respect, particles with positive surface charges showed higher r 2/r 1 ratios.

Probing the interaction between air bubble and sphalerite mineral surface using atomic force microscope.

The interaction between air bubbles and solid surfaces plays important roles in many engineering processes, such as mineral froth flotation. In this work, an atomic force microscope (AFM) bubble probe technique was employed, for the first time, to directly measure the interaction forces between an air bubble and sphalerite mineral surfaces of different hydrophobicity (i.e., sphalerite before/after conditioning treatment) under various hydrodynamic conditions. The direct force measurements demonstrate the critical role of the hydrodynamic force and surface forces in bubble-mineral interaction and attachment, which agree well with the theoretical calculations based on Reynolds lubrication theory and augmented Young-Laplace equation by including the effect of disjoining pressure. The hydrophobic disjoining pressure was found to be stronger for the bubble-water-conditioned sphalerite interaction with a larger hydrophobic decay length, which enables the bubble attachment on conditioned sphalerite at relatively higher bubble approaching velocities than that of unconditioned sphalerite. Increasing the salt concentration (i.e., NaCl, CaCl2) leads to weakened electrical double layer force and thereby facilitates the bubble-mineral attachment, which follows the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory by including the effects of hydrophobic interaction. The results provide insights into the basic understanding of the interaction mechanism between bubbles and minerals at nanoscale in froth flotation processes, and the methodology on probing the interaction forces of air bubble and sphalerite surfaces in this work can be extended to many other mineral and particle systems.

High-throughput profiling of nanoparticle-protein interactions by fluorescamine labeling.

A rapid, high throughput fluorescence assay was designed to screen interactions between proteins and nanoparticles. The assay employs fluorescamine, a primary-amine specific fluorogenic dye, to label proteins. Because fluorescamine could specifically target the surface amines on proteins, a conformational change of the protein upon interaction with nanoparticles will result in a change in fluorescence. In the present study, the assay was applied to test the interactions between a selection of proteins and nanoparticles made of polystyrene, silica, or iron oxide. The particles were also different in their hydrodynamic diameter, synthesis procedure, or surface modification. Significant labeling differences were detected when the same protein incubated with different particles. Principal component analysis (PCA) on the collected fluorescence profiles revealed clear grouping effects of the particles based on their properties. The results prove that fluorescamine labeling is capable of detecting protein-nanoparticle interactions, and the resulting fluorescence profile is sensitive to differences in nanoparticle's physical properties. The assay can be carried out in a high-throughput manner, and is rapid with low operation cost. Thus, it is well suited for evaluating interactions between a larger number of proteins and nanoparticles. Such assessment can help to improve our understanding on the molecular basis that governs the biological behaviors of nanomaterials. It will also be useful for initial examination of the bioactivity and reproducibility of nanomaterials employed in biomedical fields.

Superparamagnetic iron oxide nanoparticles: promote neuronal regenerative capacity?

Currently, we know that neuronal outgrowth during development and regeneration requires a complex interaction of intra- and extracellular molecules such as growth factors, neurotransmitters and extracellular matrix proteins (O’Donnell et al., 2009). Furthermore, the discovery of a broad spectrum of growth-promoting cues has led to novel concepts for therapeutic strategies. However, although our understanding of the molecular mechanisms underlying neuronal regeneration is constantly growing, there is still no therapy for the treatment of brain or spinal cord injuries (SCI) (Filli and Schwab, 2012). Recent attempts have been made to influence regeneration using nano-scaled particles that specifically act at the molecular level (Polak and Shefi, 2015).

ANALAYSIS OF THE EFFECTIVE PARAMETERS ON HYDRODYNAMIC DERIVATIVES' COEFFICIENTS

Abstract. The estimation of maneuvering performance of an autonomous under water vehicle (AUV) is needed to model hydrostatic, added mass, hydrodynamic and control surface forces and moments. Computation fluid dynamics (CFD) is becoming an essential tool for predicting the hydrodynamic forces of submerged bodies. In this paper ANSYS Fluent soft ware is conducted for the AUV in order to identify the hydrodynamic forces. Various angels of attack are inserted on the AUV in order to identify drag, lift and moment coefficients. Moreover, control surface forces and moments have been estimated.

Optimal Disturbance in a Flow Duct with a Lined Wall

Acoustic lining is widely used to reduce sound. However, for specific liners and under particular flow conditions, some experiments have shown that a convective hydrodynamic instability may grow on the liner and is likely to lead to a sound amplification. In this paper, such a phenomenon is studied through a direct optimal growth analysis of the linearized Euler equations in a two-dimensional flow duct with the bottom wall which is partly lined. A Discontinuous Galerkin scheme is used for spatial discretization, which proved to be quite efficient in handling the acoustic impedance discontinuity at the interface between the lined and hard wall. The optimal perturbation exhibits a spatial amplification similar to the one predicted by a local stability analysis. Moreoever, we can observe a mechanism of conversion of the hydrodynamic surface mode, which appears above the lined wall, into a high amplitude acoustic wave which travels downstream of the liner.

The Delta Model for Fresh Water Policy Analysis in the Netherlands

During dry years, such as 2003 and the early summer of 2011, the Netherlands faces water shortages, salt intrusion, navigation limitations and problems with availability of cooling water for power plants. Considering the changing climate, the frequency of these problems is expected to increase. A policy analysis using an integrated set of models has been launched by the government: the Dutch Delta Programme. The Delta model is the consistent set of models for analysing the decisions related to the long-term fresh water supply and flood risk management of the Netherlands. The country-wide SOBEK-1D hydrodynamic surface water model (LSM) was developed as part of the Delta model and forms the link between the Netherlands Hydrological Instrument (NHI) and impact assessment models for salinity, temperature, water quality, aquatic ecology and navigation. The Delta model provides a computational facility that automates the workflow of running sets of interconnected models for the national policy analysis on fresh water and various regional programmes within the Delta Programme. The Delta model, although being computationally demanding, enabled analyses of the present situation, future scenarios (2050 and 2100) and possible adaptation measures. Moreover, the Delta model has supported consistency between the national analyses and regional analyses in the Delta Programme.

Numerical analysis on molten droplet hydrodynamic deformation and surface waves under high pressure pulse

A multi-phase hydrodynamic code using volume of fluid method (VOF) is used to simulate the molten droplet deformation, and the surface waves at the stages of pressure propagation and expansion in steam explosion (SE). Both melt-liquid system and melt-gas system are simulated using the code. A benchmark case of Joseph et al.’s experimental data (1999) is performed to validate the code. In this paper, effects of vapor film and surface tension on the droplet behavior under high pressure pulse are investigated. In addition, effects of material density and pressure pulse magnitude on the droplet deformation, and the growth of surface waves are also analyzed. Results of simulation analysis suggested that vapor film can be neglected and the effect of surface tension is not significant for hydrodynamic process under high pressure pulse. Results of simulation also demonstrate that material density and pressure pulse play a significant role in the process of droplet deformation and surface wave growth. The research shows that the effect of hydrodynamic deformation is significant for droplet fragmentation, and droplet penetration can more likely be achieved by surface wave instability at the stages of propagation and expansion in steam explosion.

Effect of Dimensionless Parameters and Bubble Surface Area Flux on Flotation Rate Constant

In this study, the effect of dimensionless hydrodynamic parameters (Reynolds Number–Re, Froude Number–Fr, and Weber Number–We) and bubble surface area flux, S b, on flotation rate constant, k, of quartz particles was investigated using laboratory mechanical flotation cell. Maximum flotation rate constant was obtained at Re = 89, 800, Fr = 2.4, and We = 1558. For either more quiescent (Re < 73, 500 and Fr < 1.61) or more turbulent (Re > 98, 000 and Fr > 2.85) conditions, flotation rate constant decreased steadily. Furthermore, the effect of Reynolds number in the k–S b relationship was investigated, and model of was obtained.

Changes in air flow patterns using surfactants and thickeners during air sparging: Bench-scale experiments

Air injected into an aquifer during air sparging normally flows upward according to the pressure gradients and buoyancy, and the direction of air flow depends on the natural hydrogeologic setting. In this study, a new method for controlling air flow paths in the saturated zone during air sparging processes is presented. Two hydrodynamic parameters, viscosity and surface tension of the aqueous phase in the aquifer, were altered using appropriate water-soluble reagents distributed before initiating air sparging. Increased viscosity retarded the travel velocity of the air front during air sparging by modifying the viscosity ratio. Using a one-dimensional column packed with water-saturated sand, the velocity of air intrusion into the saturated region under a constant pressure gradient was inversely proportional to the viscosity of the aqueous solution. The air flow direction, and thus the air flux distribution was measured using gaseous flux meters placed at the sand surface during air sparging experiments using both two-, and three-dimensional physical models. Air flow was found to be influenced by the presence of an aqueous patch of high viscosity or suppressed surface tension in the aquifer. Air flow was selective through the low-surface tension (46.5dyn/cm) region, whereas an aqueous patch of high viscosity (2.77cP) was as an effective air flow barrier. Formation of a low-surface tension region in the target contaminated zone in the aquifer, before the air sparging process is inaugurated, may induce air flow through the target zone maximizing the contaminant removal efficiency of the injected air. In contrast, a region with high viscosity in the air sparging influence zone may minimize air flow through the region prohibiting the region from de-saturating.

A semiclassical collective response of heated, asymmetric, and rotating nuclei

The quasiparticle Landau Fermi-liquid and periodic orbit theories are presented for the semi-classical description of collective excitations in nuclei, which are close to one of the main topics of the fruitful activity of S.T. Belyaev. Density-density response functions are studied at low temperatures within the temperature-dependent collisional Fermi-liquid theory in the relaxation time approximation. The isothermal, isolated (static) and adiabatic susceptibilities for nuclear matter show the ergodicity property. Temperature corrections to the response function, viscosity and thermal conductivity coefficients have been derived, also in the long wavelength (hydrodynamic) limit. The relaxation and correlation functions are obtained through the fluctuation-dissipation theorem and their properties are discussed in connection to the static susceptibilities and ergodicity of the Fermi systems. Transport coefficients, such as nuclear friction and inertia as functions of the temperature for the hydrodynamic (heat-pole and first sound) and Fermi surface distortion zero-sound modes are derived within the Fermi-liquid droplet model. They are shown to be in agreement with the semi-microscopical calculations based on the nuclear shell model (SM) for large temperatures. This kinetic approach is extended to the study of the neutron-proton correlations in asymmetric neutron-rich nuclei. The surface symmetry binding-energy constants are presented as functions of the Skyrme-force parameters in the approximation of a sharp-edged proton-neutron asymmetric nucleus and applied to calculations of the isovector giant dipole resonance. The energies, sum rules, and transition densities of these resonances obtained by using analytical expression for these surface constants in terms of the Skyrme-force parameters are in fairly good agreement with the experimental data. An analysis of the experimental data, in particular the specific structure of these resonances in terms of a main, and some satellite peaks, in comparison with our analytical approach and other theoretical semimicroscopical models, might turn out to be of capital importance for a better understanding of the values of the fundamental surface symmetry-energy constant. The semiclassical collective moment of inertia is derived analytically beyond the quantum perturbation approximation of the cranking model for any potential well as a mean field. It is shown that this moment of inertia can be approximated by its rigid-body value for the rotation with a given frequency within the ETF and more general periodic orbit theories in the nearly local long-length approximation. Its semiclassical shell-structure components are derived in terms of the periodic-orbit free-energy shell corrections. An enhancement of the moment of inertia near the symmetrybreaking bifurcation deformations was found. We obtained good agreement between the semiclassical and quantum shell-structure components of the moment of inertia for several critical bifurcation deformations for the completely analytically solved example of the harmonic oscillator mean field.

A stochastic approach for the simulation of particle resuspension from rough substrates: Model and numerical implementation

This paper presents a Lagrangian stochastic model to simulate colloid resuspension from rough surfaces. For that purpose, the extension of a recent proposition is discussed as well as the details of its numerical implementation. The basis of this model is a dynamical approach which reproduces explicitly the different steps involved in a three-stage scenario of particle resuspension where particles are set in motion (first stage); roll/slide along a rough surface due to varying force moments (second stage); and can be detached when a large-scale asperity is hit (third stage). The model treats separately hydrodynamic forces (drag force), adhesion forces (mainly due to interface chemical effects) and surface roughness through a two-level description (small-scale asperities and large-scale asperities) within a unified approach that combines the effects of fluid mechanics, interface chemistry and material properties. A description of the key points of the model brings forward the important role played by the number of small-scale asperities in contact with each particle; the pivot point around which particles can roll; the streamwise kinetic energy acquired as particles roll/slide along the surface; the probability to hit a large-scale asperity and the prediction of the actual detachment. Specific methods to simulate the trajectories of these stochastic processes are detailed and validated in a step-by-step manner with a specific emphasis put on the interplay between adhesion forces and particle dynamics. Finally, once each step has been separately assessed, the complete model is evaluated by comparing predictions to a realistic resuspension test-case for airborne colloids, showing that good and consistent numerical predictions are obtained with reasonable time steps.

Topical Administration of Dual siRNAs Using Fusogenic Lipid Nanoparticles for Treating Psoriatic-Like Plaques

Psoriasis is a chronic autoimmune skin disorder with substantial negative impact on the patient's quality of life. The present study was carried out to demonstrate the efficiency of a novel topical delivery system in the transport of two siRNAs for the treatment of psoriatic-like plaques. We designed and developed a novel fusogenic nucleic acid lipid particle (F-NALP) system containing two therapeutic nucleic acids, anti-STAT3 siRNA (siSTAT3) and anti-TNF-α siRNA (siTNF-α). Novel cationic amphiphilic lipid with oleyl chains was synthesized and used in the nanocarrier system. Therapeutic efficacies of F-NALPs were assessed using an imiquimod-induced psoriatic-like plaque model. Hydrodynamic size and surface potential of F-NALPs were 102 ± 6 nm and 32.14 ± 6.21 mV, respectively. F-NALPs delivered fluorescein isothiocyanate-siRNA to a skin depth of 360 µm. F-NALPs carrying siSTAT3 and siTNF-α significantly (p < 0.05) reduced expression of STAT3 and TNF-α mRNAs and IL-23 and Ki-67 proteins compared with solution, and was superior in comparison with Topgraf(®) (GlaxoSmithKline Pharmaceuticals Limited, Maharashtra, India). Our observations demonstrate that F-NALPs can efficiently carry siSTAT3 and siTNF-α into the dermis and combination of the two nucleic acids can synergistically treat psoriatic-like plaques.

Laser-driven surface thermocapillary waves in isotropic and anisotropic liquids

Theoretical and experimental results on thermocapillary hydrodynamic surface waves induced in liquids by travelling spatially periodical distribution of light intensity are reported. The phase of local elevation in capillary waves is close to the phase of interference pattern when frequency is far from zero and from eigen frequency of free capillary waves. This phase difference is exactly π/2 for zero frequency.

Surface charge of PLA microparticles in regulation of antigen loading, macrophage phagocytosis and activation, and immune effects in vitro

The use of microparticles (MPs) as adjuvants has attracted increasing interest in vaccine delivery systems. Many physiochemical characteristics of MPs including hydrodynamic size, surface properties, and morphology can regulate the immune response. Surface charge is an important characteristic of MPs, but how it affects their adjuvanticity remains unknown. In this study, we prepared uniform-sized polylactide MPs coated with various polymers of different positive charge, and investigated how the surface charge affected antigen loading and macrophage phagocytosis and activation in vitro. A higher surface charge greatly enhanced antigen loading and antigen internalization into macrophages, promoted the expression of MHC II and CD80, and increased the secretion level of TNF-α. Taken together, these results indicated that surface charge was an important parameter for improving the adjuvanticity of MPs.

Improved streambank countermeasures: the Des Moines River (USA) case study

In the Midwestern USA, bank erosion is a common hazard due to the high erodibility of the bank soils. In this paper, an improved methodology aimed at identifying the optimal countermeasures to control bank erosion was developed and applied in two sites of the Des Moines River (USA). In situ flow measurements, bed bathymetry and soil properties were collected for providing boundary conditions and parameters of the two-dimensional, depth-averaged hydrodynamic finite element surface water modeling system (FESWMS) model. The model was used to compare the hydraulic performances of four streambank countermeasures: riprap lining (referred to as S1); a series of barbs (S2); alternating barbs and spurs (S3); and the combination of barbs with lining (S4). A key feature of FESWMS was its ability to simulate the wetting/drying conditions of mesh elements, which allowed the simulations of unsubmerged or partially submerged structures for different hydraulic conditions. This research showed that the combination of alternating barbs and spurs (S3) was the only design which provided protection during overbank flows at a competitive cost compared to the other designs analysed. The uniqueness of this methodology is found in the coupling of field measurements and theoretical approaches for depth-averaged velocity profiles to calibrate and validate a hydrodynamic model; and in the proposed design to protect streambanks from severe erosion.