Water Size Distribution Research Articles

Study on recirculating aquaculture system (RAS) in organic fish production

Abstract The growth of conventional aquaculture has created environmental issues due to excessive feeding, low dissolved oxygen level etc into the water body. Organic aquaculture is a recent development as a solution to these issues. It is a clean alternative to reduce pollution and to produce safer consumable food. In the past few decades, recirculating aquaculture systems (RAS) were introduced to maintain pond water quality through lesser water exchange, by focusing on water reuse after treatment. In this study, the technical viability of RAS was analyzed for introduction in organic aquaculture systems. Indian major carps (IMCs) were cultured through conventional methods in the three tanks of conventional system, while the same species was grown organically in another three tanks in organic system. The stocking density and physical conditions were kept same for both cultured systems. The RAS consisted of fish culture tank with an average volume of each tank was 165 m3, a screen filter, foam fractionator and trickling filter. The various water quality parameters, i.e., solid size distribution in water, and removal efficiencies in biological treatment of both systems were compared. The present study, particle size distribution of solids in water body was measured by filtration, followed by weighing of dry residue solids. Pore sizes of 1000μ, 100μ, 20μ and 3μ were employed for filtration. For organic tanks, a majority of solids are of size between 1 mm and 100 μm. The larger sized particles (> 30 μm) constitute nearly 70 % of the solids and the trait differs from the generalized conclusions of that a major part of sediments will be of sizes less than 20 μm. For the conventional tanks, majority of solids are of size between 3 mm and 20 μm and TAN shows higher removal efficiencies for effluents from organic system rather than conventional system. The results showed that organic aquaculture causes lesser pollution load per weight of fish. The particle size distribution of organic water was better compatible to screening and sedimentation than conventional water. Also the filtration efficiencies in nitrifying trickling filters of both water bodies were comparable, with that of organic water slightly on the higher side. Thus recirculating water treatment systems are introduced in organic aquaculture.

Green synthesis of nano silver by tea extract with high antimicrobial activity

In this study, a facile synthetic pathway was proposed to fabricate silver nanoparticles by using tea extract as reducing agent and stabilizer to reduce silver nitrate, which was further evaluated for the antimicrobial activity against bacterium (Escherichia coli) and pathogenic fungus of tea (Pseudopestalotiopsis theae). The average particle size of silver nanoparticles is 15.41 nm by X-ray diffraction (XRD) and Scherrer equation, the morphology is relatively regular and well dispersed by scanning electron microscope (SEM) and transmission electron microscope (TEM), the zeta potential is −13.91 ± 0.89 mV and the aggregate particle size distribution in water is around 773.49 nm. In addition, the synthesized nano silver had good antimicrobial effect on Pseudopestalotiopsis theae (P. theae) and Escherichia coli (E. coli), and the inhibition ratio was 96.05% and 61.87%, respectively. And the reaction of silver nanoparticles with bacteria and fungi could not be driven by the electrostatic interactions, but might by intermolecular forces. This study provides a facile and effective method for the preparation of nano silver, and broadens the application of nano silver in antimicrobial agent.

Complexing hemp seed protein with pectin for improved emulsion stability.

Hemp seed protein has the potential to be used in food systems as an emulsifying agent; however, there are still some shortcomings associated with hemp seed protein, such as poor solubility and tendency to aggregate. This study aims to improve the dispersibility of hemp seed protein as an emulsifier by complexing with pectin, driven by electrostatic force. Three protein to pectin ratios were used for complexation, from 1:1, 2:1 to 4:1. The complexation improved the polydispersity of hemp seed protein when dispersed in the aqueous phase. The hemp seed protein displayed multimodal size distribution in water at pH=3.0 due to aggregation, while the incorporation of pectin helped to diminish those aggregated proteins. When the hemp seed protein was used to stabilize the oil-in-water emulsion, its stabilized emulsion showed promising homogenous droplet size distribution after emulsification. However, during the accelerated storage conditions (55°C), the emulsion stabilized solely by hemp seed protein was subjected to extensive coalescence. From day 0 to 9, the droplet size (d4,3 ) increased by 50 folds from 3.215 to 161.6µm. In contrast, the hemp seed protein-pectin complex exhibited extraordinary stability during the storage test, where size evolution in all three samples was negligible compared to the emulsion stabilized by hemp seed protein. Rheological characterization suggests that pectin provided physical strength, which may help the emulsion droplets to maintain structural integrity under environmental stress. The underlying mechanism could be associated with the formation of a three-dimensional structure by pectin through bridging adjacent emulsion droplets. PRACTICAL APPLICATION: Hemp seed protein is gaining more and more attention as an emerging plant protein. Recently, hemp seed protein has been explored as an emulsifier, but its stabilized emulsion encounters instability issues during storage. Our study suggests pectin could be used as a co-stabilizer for hemp seed protein emulsions.

Determining population densities in bimodal micellar solutions using contrast-variation small angle neutron scattering.

Self-assembly of amphiphilic polymers in water is of fundamental and practical importance. Significant amounts of free unimers and associated micellar aggregates often coexist over a wide range of phase regions. The thermodynamic and kinetic properties of the microphase separation are closely related to the relative population density of unimers and micelles. Although the scattering technique has been employed to identify the structure of micellar aggregates as well as their time-evolution, the determination of the population ratio of micelles to unimers remains a challenging problem due to their difference in scattering power. Here, using small-angle neutron scattering (SANS), we present a comprehensive structural study of amphiphilic n-dodecyl-PNIPAm polymers, which shows a bimodal size distribution in water. By adjusting the deuterium/hydrogen ratio of water, the intra-micellar polymer and water distributions are obtained from the SANS spectra. The micellar size and number density are further determined, and the population densities of micelles and unimers are calculated to quantitatively address the degree of micellization at different temperatures. Our method can be used to provide an in-depth insight into the solution properties of microphase separation, which are present in many amphiphilic systems.

Passive Acoustic Method in Bubble Size Distribution Determination

The paper is considering existing methods for determining the gas phase hydrodynamic properties in liquid medium. This paper presents a passive hydroacoustic method for determining the air bubbles size distribution in water. Advantage of this method contrasting to the active ones lies in its invasiveness. Mathematical model proposed for converting the spectrum of noise emitted by a cloud of bubbles into size distribution was tested in a number of experiments. Experiments were carried out in a glass cubic reservoir filled with water. Experiment results were verified by comparison with the photometric method.

Orlistat-loaded solid SNEDDS for the enhanced solubility, dissolution, and in vivo performance.

BackgroundThe present study aimed to develop orlistat-loaded solid self-nanoemulsifying drug delivery system preconcentrate (SSP) with the minimum use of lipid excipients for the enhanced solubility, in vitro dissolution, lipase inhibition, and in vivo performance.Materials and methodsIn the screening of solubilizing vehicles, Solutol HS15 and Lauroglycol 90 were selected as the surfactant and oil phase, respectively. A pseudo-ternary phase diagram composed of Solutol HS15, Lauroglycol 90, and orlistat as an anti-obesity agent and lipid component was constructed, and the SSP regions were confirmed in terms of the particle size distribution in water, melting point by differential scanning calorimetry, and crystallinity by X-ray diffraction.ResultsPhysicochemical interaction between Solutol HS15 and orlistat resulted in SSP with various melting points in the range of 26°~33°C. The representative maximum orlistat-loaded SSP (orlistat/Solutol HS15/Lauroglycol 90=55/40/5, weight ratio) showed the melting point of 32.23°C and constructed uniform nanoemulsion with the particle size of 141.7±1.1 nm dispersed in water. In the dissolution test at pH 1.2 without any detergent, the SSP reached 98.12%±0.83% until 45 minutes, whereas raw orlistat showed no significant dissolution rate. The dissolution samples containing SSP showed a lipase inhibition of 90.42%±1.58% within 45 minutes. In terms of the reduction level of fat absorption in rats, the intake group of SSP gave a significantly higher fat excretion into stool than the one observed in the raw orlistat group (P<0.05).ConclusionIn conclusion, the suggested novel SSP formulation would be an effective and promising candidate for the treatment of obesity.

Size-segregated urban aerosol characterization by electron microscopy and dynamic light scattering and influence of sample preparation

Size-segregated particulate matter (PM) is frequently used in chemical and toxicological studies. Nevertheless, toxicological in vitro studies working with the whole particles often lack a proper evaluation of PM real size distribution and characterization of agglomeration under the experimental conditions. In this study, changes in particle size distributions during the PM sample manipulation and also semiquantitative elemental composition of single particles were evaluated. Coarse (1–10 μm), upper accumulation (0.5–1 μm), lower accumulation (0.17–0.5 μm), and ultrafine (<0.17 μm) PM fractions were collected by high volume cascade impactor in Prague city center. Particles were examined using electron microscopy and their elemental composition was determined by energy dispersive X-ray spectroscopy. Larger or smaller particles, not corresponding to the impaction cut points, were found in all fractions, as they occur in agglomerates and are impacted according to their aerodynamic diameter. Elemental composition of particles in size-segregated fractions varied significantly. Ns-soot occurred in all size fractions. Metallic nanospheres were found in accumulation fractions, but not in ultrafine fraction where ns-soot, carbonaceous particles, and inorganic salts were identified. Dynamic light scattering was used to measure particle size distribution in water and in cell culture media. PM suspension of lower accumulation fraction in water agglomerated after freezing/thawing the sample, and the agglomerates were disrupted by subsequent sonication. Ultrafine fraction did not agglomerate after freezing/thawing the sample. Both lower accumulation and ultrafine fractions were stable in cell culture media with fetal bovine serum, while high agglomeration occurred in media without fetal bovine serum as measured during 24 h.

Droplet size distribution measurement of water in kerosene by the buoyancy weighing-bar method

The buoyancy weighing-bar method (BWM) is a method that requires a simple apparatus set up yet produce the high accuracy result in particle size distribution measurement both settling and floating particles. The principle of this experiment that measurement the density change in a suspension due to particle migration is measured by weighing buoyancy against a weighing bar hung in the suspension, and the particle size distribution is calculated using the length of the weighing bar and the time–course change in the apparent mass of the weighing bar. In this study, the BWM was applied to determine the separation time and droplet size distribution for liquid-liquid systems with the different density. The mixture of 99 % of kerosene and 1 % of water were used as samples. The data obtained of separation time of water-kerosene mixture by the BWM were analyzed by the gas chromatography, and the droplet size distributions were compared to Coulter counter method. Based on the data obtained, the BWM could be used to determine the optimal time of waterkerosene separation. The BWM also could measure the droplet size distribution of water in kerosene and the data obtained were comparable to that measured by Coulter counter method. Hence, the BWM is a novel method in separation time determination of water-kerosene mixture and droplet size distribution measurement of water in kerosene.

Evaluation of modified-graphite nanomaterials in concrete nanocomposite based on packing density principles

Fresh concrete is a dispersion of particulate matter with a broad size distribution in water. Addition of graphite nanomaterials extends the size range of particulate matter well into nano-scale dimensions, which could benefit the packing of particles in fresh concrete and the engineering properties of hardened concrete materials. In order to test this hypothesis, five classes of concrete (normal-strength, high-strength, ultra-high-performance, self-consolidating normal strength, and self-consolidating ultra-high performance concrete) with different packing densities were evaluated. The Compaction Packing Model was used to calculate the packing densities of various examples of these five categories of concrete materials. The packing density was observed to be lowest for normal-strength concrete and highest for ultra-high-performance concrete. In the case of self-consolidating concrete materials, finer particulate matter was found to make a greater contribution towards raising the packing density with increasing compressive strength. In self-consolidating ultra-high-performance concrete, the effect of micro-scale fibers on improving the packing density was found to be about half that of non-self-consolidating ultra-high-performance concrete. A key finding of the analytical investigations was that graphite nanomaterials (carbon nanofibers) at very low dosages (0.04vol.% of concrete) account for 9% of the packing density improvement in ultra-high-performance concrete nanocomposites. This notable contribution at such low concentration can be attributed to the fine geometry of the nanomaterials. Experimental results were used to validate the correlation between the contributions of graphite nanomaterials to concrete material properties and the corresponding effects on the packing density of the particulate matter in fresh concrete. These correlations indicated that the Compaction Packing Model provides a viable basis for design of concrete nanocomposites.

Development of a Vinyl Ether-Functionalized Polyphosphoester as a Template for Multiple Postpolymerization Conjugation Chemistries and Study of Core Degradable Polymeric Nanoparticles.

A novel polyphosphoester (PPE) with vinyl ether side chain functionality was developed as a versatile template for postpolymerization modifications, and its degradability and biocompatibility were evaluated. An organocatalyzed ring-opening polymerization of ethylene glycol vinyl ether-pendant cyclic phosphotriester monomer allowed for construction of poly(ethylene glycol vinyl ether phosphotriester) (PEVEP). This vinyl ether-functionalized PPE scaffold was coupled with hydroxyl- or thiol-containing model small molecules via three different types of conjugation chemistries—thiol–ene “click” reaction, acetalization, or thio-acetalization reaction—to afford modified polymers that accommodated either stable thio–ether or hydrolytically labile acetal or thio–acetal linkages. Amphiphilic diblock copolymers of poly(ethylene glycol) and PEVEP formed well-defined micelles with a narrow and monomodal size distribution in water, as confirmed by dynamic light scattering (DLS), transmission electron microscopy, and atomic force microscopy. The stability of the micelles and the hydrolytic degradability of the backbone and side chains of the PEVEP block segment were assessed by DLS and nuclear magnetic resonance spectroscopy (1H and 31P), respectively, in aqueous buffer solutions at pH values of 5.0 and 7.4 and at temperatures of 25 and 37 °C. The hydrolytic degradation products of the PEVEP segments of the block copolymers were then identified by electrospray ionization, gas chromatography, and matrix-assisted laser desorption/ionization mass spectrometry. The parent micelles and their degradation products were found to be non-cytotoxic at concentrations up to 3 mg/mL, when evaluated with RAW 264.7 mouse macrophages and OVCAR-3 human ovarian adenocarcinoma cells.

Synthesis of thiol modified CdSe nanoparticles/P3HT blends for hybrid solar cell structures

Thioglycolic acid (TGA) capped cadmium selenide (CdSe) nanoparticles were synthesised in aqueous medium through wet chemical method using sodium selenite as the selenium source. The synthesised particles were transformed into organic medium using 1-dodecanethiol through efficient partial ligand exchange strategy. The UV–visible spectra recorded for the particles reveal the size distribution in water as well as in organic solvent. TEM analysis of the synthesised particles shows the size and the nature of distribution of the particles in solution. The phase transferred particles were blended with the polymer poly-3-hexyl thiophene (P3HT) in chloroform. UV–visible and photoluminescence spectra of the polymer with various volumes of the nanoparticles clearly indicate the effective coupling and the efficient charge transfer process in the blend. SEM analysis of the CdSe–P3HT blends confirms the effective distribution of the nanoparticles in the polymeric matrix. AFM studies reveal the morphology of the nanoparticles and the phase separation process in the blends.

Facile and green synthesis of silver nanoparticles in quaternized carboxymethyl chitosan solution

A facile and green method to synthesize stable Ag nanoparticles (Ag NPs) with a narrow size distribution in water is reported. Water-soluble quaternized carboxymethyl chitosan (QCMC) with a surfactant-like structure was used as both a reducing and stabilizing agent under microwave irradiation via the modified Tollens reaction. In order to study the preparation mechanism, carboxymethyl chitosan (CMC) and quaternized chitosan (QCS) were compared as both reducing and stabilizing agents. Full characterization was performed using UV–vis, XRD, TEM, AAS, FT-IR, NMR and TGA. The results revealed that the prepared Ag NPs were mostly spherical with a small proportion being cylinders or cuboids; they were stable due to the package of the macromolecules; the diameters were 10.24 ± 3.13 nm. The Tollens reaction followed first order kinetics, and the Ea was 102.4 kJ mol−1 for QCMC/Ag NP composite. During the growth of the Ag NPs, some quaternary ammonium groups and carboxymethyl groups were respectively oxidized to −CH2COCH3 and −CH3 groups, and the quaternary ammonium groups were more helpful for the growth of Ag NPs than the carboxymethyl groups. In addition, QCMC/Ag NP composite had much higher thermal stability than QCMC.

Higher order structures of a bioactive, water-soluble (1→3)-β-d-glucan derived from Saccharomyces cerevisiae

Water-soluble (1→3)-β-d-glucans with 1,6-linked branches (SBG), originally isolated from the cell walls of Saccharomyces cerevisiae and partially depolymerised to a weight average degree of polymerisation (DPw) in the range 120–160 for optimal performance in wound healing applications, were studied by dynamic light scattering (DLS), SEC MALLS and AFM. Results indicate that dilute aqueous SBG solutions (1μg/ml to 3mg/ml) contain higher order structures with a very wide size distribution in water (10–500nm), corresponding to a mixture of single chains, multi-chain aggregates including triple-stranded motifs, and particulate materials. The latter were enriched in longer chains compared to non-particulate fractions. The size distribution of SBG aggregates shifted to slightly lower values upon heating, but showed hysteresis upon cooling. AFM images prepared from very dilute aqueous solution (1–5μg/ml) analysis showed by comparison to other (1→3)-β-d-glucans that some of the structures were the triple helical species coexisting with larger aggregates and single chains, in contrast to carboxymethylated SBG, which contained predominantly single chains. The ability to control the aggregation behaviour of SBG enables tailoring of the physical, and possibly bioactive, properties of SBG preparations.

Effect of Focused Ultrasound on Residual Particle Size Distribution in Water

Effect of Focused Ultrasound on Residual Particle Size Distribution in Water

Effect of Focused Ultrasound on Residual Particle Size Distribution in Water

The residual particle distribution in pure water could be a problem in the nanoscience fields because nanoparticles are usually suspended in pure water such as deionized or distilled water. The effect of ultrasound on the residual particle distribution in pure water should be analyzed because the nano particles used in nanoscience are usually dispersed using ultrasound power. In this study, using a cylindrical piezoelectric vibrator, a noncontact-type focusing ultrasound system was fabricated to keep the purity of the water. The residual particle distribution in pure water was investigated. The number of residual particles increased as the ultrasound exposure time increased.

Facile synthesis of concentrated gold nanoparticles with low size-distribution in water: temperature and pH controls

The citrate reduction method for the synthesis of gold nanoparticles (GNPs) has known advantages but usually provides the products with low nanoparticle concentration and limits its application. Herein, we report a facile method to synthesize GNPs from concentrated chloroauric acid (2.5 mM) via adding sodium hydroxide and controlling the temperature. It was found that adding a proper amount of sodium hydroxide can produce uniform concentrated GNPs with low size distribution; otherwise, the largely distributed nanoparticles or instable colloids were obtained. The low reaction temperature is helpful to control the nanoparticle formation rate, and uniform GNPs can be obtained in presence of optimized NaOH concentrations. The pH values of the obtained uniform GNPs were found to be very near to neutral, and the pH influence on the particle size distribution may reveal the different formation mechanism of GNPs at high or low pH condition. Moreover, this modified synthesis method can save more than 90% energy in the heating step. Such environmental-friendly synthesis method for gold nanoparticles may have a great potential in large-scale manufacturing for commercial and industrial demand.

A New Route for Mass Production of Uniform Metal Nanoparticles in Water by Means of Laser Light Induced Processes

In this contribution, we report a new route for mass fabrication of metal nanoparticles with monodisperse shape and narrow size distribution in water applying exclusively physical processes. For this purpose, we have combined pulsed laser ablation with the technique of selective laser tailoring. For example, pulsed laser ablation from a gold plate in water results in a large amount of nanoparticles with radii in the range of R = 75 nm with a relatively broad size distribution of sigma = 31%. This broad size distribution has been subsequently narrowed in a single irradiation step to sigma = 20% without a significant change of the mean nanoparticle radius utilizing selective laser tailoring. The main advantage of the laser based process, besides rapid processing, is that no chemicals, which are undesired for many applications, are necessary. Hence, mass production of nanoparticles with narrow size and monodisperse shape distribution in water becomes feasible.

Synthesis of Monodisperse Quasi-Spherical Gold Nanoparticles in Water via Silver(I)-Assisted Citrate Reduction

We demonstrate a simple and reproducible way to produce quasi-spherical Au nanoparticles (NPs) with a fairly narrow size distribution in water by rapidly adding a mixture solution of HAuCl(4), sodium citrate, and a trace amount of silver nitrate into boiling water. The sizes of quasi-spherical Au NPs obtained increases from 12 +/- 1 nm to 18 +/- 3, 25 +/- 3, and 36 +/- 3 nm with decrease of the citrate concentration in a fairly linear way. The present protocol can efficiently minimize the effect of citrate to buffer the pH of the reaction media and thus change the type and reactive activity of auric ions and significantly speed up the nucleation and growth rate of Au NPs. The presence of Ag(+) ions can not only suppress the secondary nucleation but also reshape the polycrystalline Au NPs into a quasi-spherical shape. In the case of synthesis of Au NPs of sizes ranging from 10 to 36 nm, our approach efficiently makes up the shortages of the classical Turkevich method with respect to the reproducibility and uniformity of the NP size and shape.

High-loading nanosized micelles of copoly(styrene–maleic acid)–zinc protoporphyrin for targeted delivery of a potent heme oxygenase inhibitor

Amphiphilic styrene–maleic acid (SMA) copolymer efficiently formed micelles with a potent heme oxygenase inhibitor–zinc protoporphyrin (ZnPP). The micelles were constructed by subtle pH adjustments to form non-covalent interaction between the hydrophobic ZnPP and amphiphilic SMA. The micelles (SMA–ZnPP) thus formed were nanoparticles with narrow size distribution in water (mean diameter 176.5 nm), having tunable loading (from 15% to 60% w/w of ZnPP) with remarkable aqueous solubility. SMA–ZnPP had an average molecular size of 144 kDa as determined by size-exclusion chromatography (SEC), this size is a marked increase from the molecular weight of free ZnPP (626.03 Da), suggesting the formation of micellar structure. The micelles showed a constant ZnPP release rate of about 0.5%/day in vitro at neutral pH. SMA–ZnPP micelles inhibited splenic microsomal HO-1 activity, in a competitive and dose-dependent manner, with an apparent inhibitory constant ( K i) of 0.12 μ m, comparable to free ZnPP and also exhibited marked cytotoxic effect on KYSE-510 human esophageal cancer cells. The unique features of SMA–ZnPP micelles are that they are nanoparticles in aqueous solution having high water solubility and loading, yet macromolecular in nature, which can be beneficial in targeted release of a potent HO-1 inhibitor.

Synthesis and characterization of a novel amphiphilic chitosan–polylactide graft copolymer

Water soluble chitosan (CS) derivatives containing polylactide unit were synthesized by reacting dl-lactide (DLLA) with chitosan in dimethyl sulfoxide solution in the presence of triethylamine. The chemical structure and physical properties of chitosan derivatives were characterized by FTIR, 1HNMR, TGA and XRD. Formation and characteristics of polymeric micelles of graft copolymers were studied by fluorescence spectroscopy and dynamic light scattering (DLS) method. The critical micelles concentration (cmc) of polymeric amphiphiles was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe. The cmc value of DLLA/CS (11:1) ( dl-lactide/aminoglucoside units molar ratio=11:1) in water was 6.49×10 −2 mg/ml. The size of micelles and their size distribution in water were measured by DLS. Mean diameter of the polymeric amphiphiles micelles of DLLA/CS (11:1) in water was 154 nm with an unimodal size distribution (polydispersity= μ/ Γ 2=0.03). The spherical micelles were observed by transmission electron microscopy (TEM).