Particle Size Distribution Index Research Articles

Application of nanostructured lipid carriers containing α-tocopherol for oxidative stability enhancement of camelina oil

In the present study, nanostructured lipid carriers (NLCs) were prepared using the hot homogenization method with high shear force. The optimal amounts of solid/liquid lipids ratio (glyceryl stearate/oleic acid), the aqueous phase of surfactant (tween 80/water), and α-tocopherol (αt) as constituents of NLCs were obtained using response surface methodology via Box–Behnken design and the encapsulation efficiency and loading capacity percentages of NLCs containing αt (NLCs- αt) were recorded as responses. The optimum NLCs-αt characterized in terms of particle size, particle size distribution index (PDI), scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transfer spectroscopy infrared (FTIR) analyses. The results indicated that NLCs in the optimum point had a particle size of 198 nm and PDI of 0.28 with a spherical shape and a smooth surface. The results of DSC and FTIR analyses showed that there is no interaction between the active compounds and obtained NLCs. The release behavior of αt from NLCs-αt in the simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) revealed that the\\orsmeyer-Peppas model was the best model for the evaluation of the release kinetic of αt. It was observed that the addition of NLCs-αt reduced the DPPH radical scavenging (83.33–46.25%), TPC (228.8–169.0 mg GAE/g) and oxidative stability (4.21–3.30 h), but increased peroxide value (0.87–2.59 meqO2.kg−1), anisidine value (0.63–1.50) and TOTOX value (2.37–6.68) after 90 days of storage. Moreover, the antioxidant activity of Camelina oil containing optimum NLCs-αt (46.25%) was comparable to Camelina oil containing the TBHQ (49.45%) as a reference, but it was higher when rosemary essential oil (REO) was added with NLCs-αt (58.73%) (after 90 days of storage). In general, it can be concluded that the optimum NLCs have tremendous potential for encapsulation of αt and deliver the extraordinary antioxidant effect to Camelina oil when they are added to Camelina oil with REO.

Antifriction and anti-wear performances of bionic lubricating fluid containing gelatin nanoparticles for artificial joint materials

The antifriction and antiwear effects of gelatin nanoparticles (GLN-NP) on artificial joint materials in bionic joint lubricant were investigated to provide a theoretical basis for the development of new bionic joint lubricant. GLN-NP was prepared by cross-linking collagen acid (type A) gelatin with glutaraldehyde by acetone method, and the particle size and stability of GLN-NP were characterized. The biomimetic joint lubricants with different concentrations were prepared by mixing 5, 15, and 30 mg/mL GLN-NP with 15 and 30 mg/mL hyaluronic acid (HA), respectively. The friction reduction and antiwear effects of the biomimetic joint lubricants on zirconia ceramics were investigated on a tribometer. The cytotoxicity of each component of bionic joint lubricant on RAW264.7 mouse macrophages was evaluated by MTT assay. The particle size of GLN-NP was about 139 nm, and the particle size distribution index was 0.17, showing a single peak, indicating that the particle size of GLN-NP was uniform. In complete culture medium, pH7.4 PBS, and deionized water at simulated body temperature, the particle size of GLN-NP did not change more than 10 nm with time, indicating that GLN-NP had good dispersion stability and did not aggregate. Compared with 15 mg/mL HA, 30 mg/mL HA, and normal saline, the friction coefficient, wear scar depth, width, and wear volume were significantly reduced by adding different concentrations of GLN-NP ( P<0.05); there was no significant difference between different concentrations of GLN-NP ( P>0.05). Biocompatibility test showed that the cell survival rate of GLN-NP, HA, and HA+GLN-NP solution decreased slightly with the increase of concentration, but the cell survival rate was more than 90%, and there was no significant difference between groups ( P>0.05). The bionic joint fluid containing GLN-NP has good antifriction and antiwear effect. Among them, GLN-NP saline solution without HA has the best antifriction and antiwear effect.

Detection of marine aerosols using ocean colour sensors

Ocean colour sensors are equipped with atmospheric correction bands operating in the near infrared region of the spectrum. At these wavelengths, the ocean surface, because of high infrared absorption by water, acts as a dark background and the sensor detected radiance is due to solar radiation backscattered by the atmospheric air molecules and aerosols called Rayleigh and aerosol path radiances respectively. From the radiances in the atmospheric correction bands, after accounting for Rayleigh path radiance, it is possible to determine aerosol parameters like aerosol optical depth (AOD) and particle size distribution index. &#x0D; &#x0D; While sensors like IRS P3 MOS-B, IRS P4 OCM, NOAA-AVHRR, etc detect AOD in the total atmospheric column, IRS P3 MOS-A sensor can detect AOD in two atmospheric layers by exploiting the differential absorption property of oxygen at four narrow band channels at the O2 A band around 760nm. The method of determination from ocean colour sensors and the results from IRS P3 MOS-B, IRS P4-OCM and IRS P3 MOS-A radiance data are presented and discussed.

Physically-Based Particle Size Distribution Models of Urban Water Particulate Matter

A particle size distribution (PSD) of particulate matter (PM) is a primary metric to examine PM transport and fate, as well as PM-bound chemicals and pathogens in urban waters. To facilitate physical interpretation and data sharing, a series of concise analytical models are examined to reproduce unit operation (UO) influent and effluent PSD data and indices. The models are a (1) single-parameter exponential and two-parameter (2) gamma, (3) lognormal, and (4) Rosin-Rammler distributions. Two-parameter models provide physical interpretations for the central tendency of PM diameters, and shape as an index of PSD hetero-dispersivity. Goodness-of-fit is used to test models and PSDs. For influent data from two disparate areas, a paved source area and a larger watershed delivering unique PSDs, lognormal and gamma models provide consistent representation of influent and effluent complexity. In these areas, contrasting UOs (a clarification basin and a volumetric filter), subject to type I settling, scour, and filter PM elution, are differentiated based on flow, surface area, volume, and residence time. Surface overflow rate (SOR) as a common heuristic design tool for only type I settling is used to further test PSD models by simulating effluent PSDs for a scaled basin design. Lognormal and gamma models of SOR-generated effluent PSDs were not statistically different. In conclusion, two-parameter PSD models have physical interpretations and lower errors compared to an exponential model. Gamma and lognormal distributions are physically-based models that reproduce actual complex influent or effluent or through SOR as a tool for PSD transformation. Results indicate that PSD models and parameters can be applied to evaluate behavior of common UOs.

Preparation and Properties of Hydrophilic Rosin-Based Aromatic Polyurethane Microspheres

Hydrophilic aromatic polyurethane (HAPU) microspheres were prepared through dispersion polymerization of a rosin-based polyurethane dispersion with C=C and styrene (St). The effects of the monomer ratio (i.e., waterborne rosin-based aromatic polyurethane (WRPU) to St), dispersant level, and reaction temperature on the properties of the microspheres were investigated; the effects of pH and adsorption temperature on the adsorption capacity of Orange II were also studied. The microspheres were characterized using Fourier transform infrared spectroscopy, energy-dispersive spectrometry, thermogravimetric analysis, laser particle size analysis, and scanning electron microscopy. The results showed that HAPU microspheres have been successfully synthesized and the produced microspheres exhibited good thermal stability and monodispersion. The optimum reaction conditions for the preparation of the microspheres were determined as a monomer ratio (mWRPU/mSt) of 6:4 with 8 wt % poly(vinyl pyrrolidine) (on the basis of the mixed monomer) at 80 °C for 8 h. Under these conditions, the average particle size of the synthetic microspheres was 120 nm and the particle size distribution index was 0.442. The microspheres’ adsorption capacity for Orange II reached 17.53 mg·g–1 when the solid–liquid ratio was 1 g·L–1, with an initial concentration of 100 mg·L–1 at pH 5, and the adsorption was conducted at 313 K for 3 h.

Kinetic Analysis of Copper Sulfide (Chalcopyrite) Dissolution by Moderately Thermophilic Bacteria

ABSTRACTThe objective of this study was to improve the basic understanding of copper sulfide minerals dissolution during bioleaching of flotation concentrate and to analyze the dissolution kinetic. The results show that the sulfide mineral dissolution kinetic changes with operation time. Both surface reaction and diffusion through product layer were found to be effective parameters for the rate of reaction with various degrees of influence. In other words, the whole dissolution process can be divided into two intervals. At the beginning, the effect of surface reaction on the reaction rate is obvious. With increasing operation time and formation of layer on the surface of copper sulfides, the influence of diffusion through the layers increases. However, the dissolution rate depends also on the particle size distribution index (d80) and pulp density. With decreasing particle size and pulp density, the influence of surface reaction on the dissolution rate is increasing more than that of diffusion through layers.

Secondary self-assembly behaviors of PEO-b-PtBA-b-PS triblock terpolymers in solution

A series of PEO45-b-PtBA53-b-PS x (x = 42, 84, 165) triblock terpolymers were synthesized by the atom transfer radical polymerization and characterized by size exclusion chromatography and 1H NMR. Their self-assemblies were conducted by a two-step hierarchical self-assembly method and a one-step dialysis method and the self-assembly behaviors were investigated. The morphologies, sizes, and size distributions of micelles produced by the self-assembly were determined by transmission electron microscopy and dynamic light scattering. The secondary self-assembled structure of PEO45-b-PtBA53-b-PS x obtained by the two-step hierarchical self-assembly could be controlled by tuning the length of PS block, the core forming block. The micelles were uniform with diameters of 20–25 nm and their size distributions, except for that of PEO45-b-PtBA53-b-PS165, were narrow with particle size distribution indexes ranging from 0.014 to 0.246. The one-step dialysis of the triblock terpolymers produced vesicular micelles with distinct vesicle walls that exhibited similar thicknesses. The vesicles did not show significant aggregation. The size distribution of PEO45-b-PtBA53-b-PS42 vesicle was the narrowest with a particle size distribution index value of 0.135. The PEO45-b-PtBA53-b-PS165 vesicles tended to overlap with each other.

Scattering spectrum properties and their relationship to biogeochemical parameters: a case study in Taihu Lake

The scattering spectrum properties of highly turbid and eutrophic inland case 2 water from Taihu Lake were studied during three cruises from 2006 to 2007. The scattering [bp(λ)] and backscattering [bbp(λ)] coefficients and the backscattering probability (B) for Taihu Lake were found to show a clear spectral dependence, and this dependence was well simulated by a power-law function. This dependence, however, became weak when algae dominated the sample points. The mean values of the power-law index for bp(λ), v, in Oct 2006, Mar 2007 and Nov 2007 were −0.6712, −0.8129 and −0.7600, respectively. To interpret the spectral characteristics and mechanisms of bp(λ) and bbp(λ), water samples were collected simultaneously for the biogeochemical characterization of suspended particles. The average values of the specific scattering coefficients for total suspended matter, inorganic suspended matter (ISPM) and organic suspended matter (OSPM) were 0.634 (550 nm), 1.057 (532 nm), and 0.396 g m−2 (532 nm), respectively. The power-law index of bbp(λ) (Y) was significantly related to ISPM/OSPM and bbp(532 nm), but only weakly related to the particle size distribution index. The mean (spatial and wavelength) values of B in Oct 2006, Mar 2007, and Nov 2007 were 0.0108, 0.0138, and 0.0125, respectively. B decreases with increasing ISPM concentration because of the large contribution of ISPM to bb(λ) and the strong restraint on bbp(λ) caused by the multi-scattering effect under high-turbidity conditions.

Preparation of High Solid Content Emulsion with Core-Shell Structure

Core-shell copolymer emulsion of P(St + AA)/P(MMA + BA +DMAM) with solids content up to 60% was synthesized by the semi-continuous seed emulsion polymerization in which the pre-emulsified monomers were added dropwise. The effects of polymerization technique, the contents of seed emulsion, the amounts of emulsifier, the concentration of initiator, solid content, and polymerization temperature on emulsion particle size and its distribution were investigated. The emulsion particle morphology was characterized by transmission electron microscopy (TEM). The results indicated that the average particle size was within 200–600 nm and the particle size distribution index within 1.2–1.4. The particle size displays multidispersity.

Waterborne polyurethane and modified polyurethane acrylate composites

Waterborne polyurethane (PU) and a series of PU acrylate (PUA) composite dispersions were synthesised from isophorone diisocyanate, polyester polyols, dimethylol propionic acid, hydroxyethyl methyl acrylate, butyl acrylate and methyl acrylate. Fourier transform infrared, ultraviolet visible and differential scanning calorimetry were used to demonstrate structures, optical transparency and thermal stabilities of PU and PUA. The PUA sample had lower glass transition temperature of hard segment and higher decomposition temperature than the PU sample. Performances of the dispersion and film were studied by means of apparent viscidity, particle size and particle size distribution index, surface tension and mechanical property. The results indicated that the solvent resistance and mechanical property of PUA film were improved compared with the pure PU film. The obtained stable PUA composite samples have excellent integrated properties and have a great potential application in meeting the highly diversified demands in modern technologies, such as coatings, leather finishing, adhesives, sealants, rubbers, plastic coatings and wood finishes.

Preparation of polymer nanocapsules for use as carriers via one-step redox interfacially initiated miniemulsion polymerization

In this work, one-step redox interfacially initiated miniemulsion polymerization (IMEP) was employed to fabricate polystyrene (PS) nanocapsules 80 nm in diameter with a 2,2′-bipyridine core by the redox-initiated coupling of cumene hydroperoxide (CHPO) to iron(II) sulfate (FS) using waterborne polyurethane (WPU) as surfactant and hexadecane (HD) as costabilizer. The morphology of the nanocapsules was characterized by transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). Dynamic light scattering (DLS) was used to determine the size and polydispersity of the nanocapsules. It was found that the latexes prepared by miniemulsion polymerization via the redox-initiated method had relatively small diameters (40–100 nm) and a relatively narrow particle size distribution index (PDI: 0.086–0.124), which indicated that polymeric nanoparticles with small diameters and a narrow PDI can easily be prepared via one-step IMEP. The release of 2,2′-bipyridine from the nanocapsules was monitored by UV-visible spectroscopy. These results indicate that polymeric nanocapsules with a functional liquid core can be successfully fabricated via IMEP.

The use of a comparative particle size distribution index for the numerical classification of soil parent materials: application to mollisols of the argentinian pampa

A method to estimate the magnitude of discontinuities or similarities in parent materials having equivalent mineralogical composition is proposed. It is based on a particle size distribution index which compares for two samples the weight percentages of all fractions taken between selected size limits. The indexes form a matrix and are used to construct a dendrogram which illustrates the clustering into groups. The calculations are carried out by computer using a Fortran programme. The technique was applied to a set of soil samples of Mollisols in the humid undulating pampa in Argentina and good agreement with field observations was obtained.