Photon Correlation Spectroscopy Methods Research Articles

Investigating the use of titanium dioxide (TiO2) nanoparticles on the amount of protection against UV irradiation

In this study, three samples of commercial titanium dioxide nanoparticles (TiO2) in different sizes were used to investigate their effect on the formulation of sunscreen creams. The aim was to evaluate their role in the performance of sunscreens (i.e. SPF, UVAPF, and critical wavelength). Then the particle size of these samples was determined by photon correlation spectroscopy methods. As a result, the size of primary particles was reduced by using milling and homogenization methods at different times. The results showed that the particle size of samples TA, TB, and TC in the ultrasonic homogenizer decreased from 966.4, 2745.8, and 2471.6 nm to 142.6, 254.8, and 262.8 nm, respectively. These particles were used in the pristine formulation. Then the functional characteristics of each formulation were determined by standard methods. TA had the best dispersion in cream compared to other samples due to its smaller size (i.e. 142.6 nm). For each formulation, two important parameters, including pH and TiO2 dosage, were investigated in different states. The results showed that the formulations prepared with TA had the lowest viscosity compared to formulations containing TB and TC. SPSS 17 statistical software analysis of variance showed that the performance of SPF, UVAPF and λc in formulations containing TA had the highest levels. Also, the sample containing TAU with the lowest particle size values had the highest protection against UV rays (SPF). According to the photocatalytic functionality of TiO2, the photodegradation of methylene blue in the presence of each nanoparticle of TiO2 was studied. The results showed that smaller nanoparticles (i.e. TA) had more photocatalytic activity under UV–Vis irradiation during 4 h (TA (22%) > TB (16%) > TC (15%)). The results showed that titanium dioxide can be used as a suitable filter against all types of UVA and UVB rays.

Modelo matemático para determinar a duração do processo de salgagem e a concentração de sal no peixe

Abstract The purpose of this scientific work is to build a diffusion model based on Fick's second law. The model is designed to determine the salting process duration and salt concentration in the fish muscle tissue (Atlantic herring). The method of photon correlation spectroscopy (PCS) by a certified Photocor FC correlator device was used. The device operating principle is based on Rayleigh radiation scattering, which allows us to directly determine the effective diffusion coefficients, taking into account all factors, without singling out a specific one. This research presents the spatiotemporal distributions of effective diffusion coefficients in a herring sample during brine salting. Formulas for calculating the salting duration and the average salt concentration in the thickness of fish muscle tissue are presented, and the time of reaching the sample center by salt and the average salt concentration in it were estimated. These parameters could be widely used for the finished product quality and the technical and economic indicators of production improvement. The average effective diffusion coefficient De through the sample thickness was used for calculation. The salting duration for a 30 mm thick herring sample with a saturated salt solution was 8.74 hours until the average salinity of the sample was 4.7%.

A study of the photocatalytic properties of chitosan-TiO2 composites for pyrene decomposition

In this work, nano- and microcomposites of chitosan-TiO2 were developed for the photocatalytic decomposition of pyrene, which is one of polycyclic aromatic hydrocarbons. TiO2 nanoparticles were synthesized by laser ablation, and their sizes were determined using the photon correlation spectroscopy method. Nano- and microcomposites based on chitosan with different TiO2 particle contents were manufactured. The work studies the effect of nano- and microparticles of TiO2 in the composition of manufactured nanocomposites on the photodegradation of pyrene in model solutions of dimethyl sulfoxide under ultraviolet radiation. To assess the decrease in pyrene concentrations in solutions, the authors used the method of luminescent analysis. Based on the results of the conducted studies, pseudo-first-order kinetic graphs for pyrene degradation in solutions were plotted. The analysis proves the efficiency of the obtained chitosan-TiO2 composites for the photocatalytic decomposition of pyrene. In 60 minutes, 68 % and 55 % of pyrene were photodegraded under ultraviolet irradiation using chitosan-TiO2 composites with TiO2 nanoparticles and with TiO2 microparticles, respectively. The developed chitosan-TiO2 composites are prospective photocatalytic materials for the decomposition of polycyclic aromatic hydrocarbons in aqueous media. The method of manufacturing composites does not require expensive equipment, and they are also convenient for performing photocatalytic reactions.

Study of used marine oils by the photon correlation spectroscopy method

In this paper, we investigate the possibility of using the method of photon correlation spectroscopy for diagnostics of marine engines based on used engine oil in order to improve efficiency and safety of operation of sea vessels. The study used the dynamic light scattering (DLS) method to measure correlation functions and then to obtain distributions of correlation times, diffusion coefficients and particle sizes. To invert the Laplace transform, a method based on standard deviation minimization and regularization (RILT) was used, modified to find the distribution of correlation times. It has been found that the distributions of the hydrodynamic radii of the particles for fresh and used oils differ significantly. By the nature of the distribution of large particles, it has been found that the level of aggregation or micelle formation of the polymer of the viscosity modifier decreases in waste oils. It is shown that the dynamic light scattering method makes it possible to obtain parameters suitable for analyzing the state of engine oil and for obtaining diagnostic data on the state of the engine for used oil.

Investigation of the influence of Zinc-containing compounds on the components of the colloidal phase of milk

Abstract To solve the problem of insufficient intake of essential macro - and micronutrients into the human body, particularly in the case of the essential trace element Zinc, the possibility of enriching a socially significant product (milk) with various forms of Zinc is considered. The influence of Zinc-containing compounds on the colloidal milk system's dispersed composition and stability, photon correlation spectroscopy methods, acoustic and electroacoustic spectroscopy was established in this research. It has been shown that Zinc lysinatoriboflavinate, is a colloidal and chelated organic form of the essential trace element Zinc, having the most negligible effects on the composition and stability of the dispersed phase particles. This increases the average hydrodynamic radius of the dispersed phase by 5% and the ζ-potential by 10%. A quantum-chemical simulation of the interaction of milk κ-casein sites with various forms of the essential trace element Zinc in the QChem program was performed using the IQmol molecular editor. The mechanism of action of various forms of Zinc on the components of the dispersed system of milk, in particular milk protein (casein), is suggested.

Hydrometallurgical Synthesis of Nickel Nano-Sulfides from Spent Lithium-Ion Batteries

By developing technologies, spent lithium-ion batteries (LIBs) are considered a great source of nickel-cobalt ions to fabricate metal sulfide nanoparticles. However, the presence of unnecessary ions such as manganese and lithium may hamper the formation of pure metal sulfide nanostructures where the utilization of proper ligand(s) can be very critical. For this reason, the present study initially introduces a promising and cost-effective acidic leaching followed by precipitation and thermal treatment (~250 °C, 1 h) processes to fabricate pure NiS nanopowders from the LIBs, while considering potassium amyl xanthate as the precipitating agent. The produced nanoparticle’s size and structure were characterized by commonly used and advanced analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS), and inductively coupled plasma optical emission spectrometry (ICP-OES). The elemental distributions and functional groups were analyzed through energy dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR) methods. The characteristic analyses of the spherical-like NiS particles showed a mean particle size of 61 ± 2 nm (by TEM) and 64 nm (through the PCS method) with high purities approved via XRD and EDS analyses. Moreover, comparing the obtained XRD data with the standard ones showed a perfect match with the hexagonal structure of the NiS phase. We finally concluded that such a presented approach is very practical and efficient for converting the LIBs to an extremely valuable product. Future studies are suggested for the fundamental conceptualization of the processes.

Photon correlation spectroscopy in the fish salting process

The current study experimentally investigates the innovative photon correlation spectroscopy method application in fish salting process. The method is based on the Rayleigh scattering of light by a substance. The experiment aims to study the mass transfer laws, as well as technological and practical aspects of the fish salting process in brine without circulation. The paper focused on spatio-temporal dependence of the salt diffusion coefficients in the fish-brine system and their correlation with temperature, indicating that at a temperature close to 8°C a diffusion-osmosis equilibrium occurs between the brine and the muscle tissue of fish. The salt diffusion rate was estimated, confirming the validity of the Crean’s frontal theory of salt mass transfer in muscle tissue of fish. Based on the Stokes-Einstein equation, it was shown that the dynamic viscosity of fish tissue fluid could be determined by changing the diffusion coefficient and the diffusing particles size. Practical applications Fish salting is an important preservation method in many countries. The present work seeks to investigate the salting of herring, as it is prone to ripening during this process. Excessive sodium chloride consumption is known to have a negative effect on humans. At the same time, the salt content in the product is interrelated with its preservation effect. In this regard, it is necessary to accurately calculate the specified salt concentration in the finished product for the optimal shelf life. Improvement of this process requires a better understanding of the mass-transfer mechanisms using modern investigation methods. Research focuses on spatio-temporal salt distribution in fish muscle tissue to arrive at clear conclusions, which can facilitate the improved production of salted fish and can be widely used in the food industry for processing and preserving fish or fish products.

MAINTAINING STABLE NANODISPERSED CERIUM OXIDE FOR HEAT TRANSFER PROCESSES

The introduction of heat carriers progressive types causes the productivity of heat exchange systems to increase. One of the challenges in thermal applied applications is the search for heat carriers that will provide revolutionary indicators of thermal conductivity and stability over time, thereby increasing the order of the heat transfer processes efficiency magnitude. The paper describes the creation of stable colloidal solutions using cerium oxide and organic stabilizers to provide better heat exchange performance compared to true solutions. Cerium oxide colloids were obtained by precipitation of the oxide from an aqueous solution of cerium nitrate with an aqueous ammonia solution in the presence of a polymer under vigorous stirring at room temperature. A number of cerium oxide nanosized dispersions, stabilized with polyvinylpyrrolidone, with a particle size of 1–10 nm were obtained. The content of CeO2 in the obtained dispersions was 1.72.10–3, 5.15.10–3, 8.6.10–3, 1.21.10–2, 1.72.10–2 % at a polymer content of 1.10–3 mol/l, the pH of the dispersions was 8–9. Electron microscopic images of the obtained nanodispersions showed a colloidal particles narrow distribution and cerium oxide nanoparticles in size. Colloidal particles are macromolecular tangles of polyvinylpyrrolidone with oxide nanoparticles strung in them. A volume of 20–50 nm organic matrix contains 10–40 particles of 1–10 nm cerium oxide. The particle size distributions of the dispersions established by the photon-correlation spectroscopy method have two areas of maxima for each sample. The first maximum for the dispersions of all investigated concentrations refers to particles with a diameter of 5–6 nm, which, in our opinion, are particles of cerium oxide, both in polymer beads and probably free from the stabilizer. Another maximum, depending on the sample, is observed at 30–70 nm or 100–300 nm, and relates to colloidal particles of PVP with cerium oxide encapsulated particles. The static stability of the cerium oxide obtained nanodispersions with polyvinylpyrolidone for two years under standard conditions is comparable to the true polymer solution. It is proposed by the method of UV spectroscopy to control the reproducibility of the obtaining materials technology. Tests of the thermal conductivity of the obtained 1.72.10–3 % stable cerium oxide nanodispersion were performed at 50 °C relative to distilled water with a thermal conductivity coefficient of 0.65 W/(m·deg). We found an increase in the coefficient for nanodispersions by 4–6 %, which is a significant value for dilute solutions. Ref. 15, Fig. 4 .

SYNTHESIS OF BIOLOGICALLY ACTIVE COPPER SOLS IN PRESENCE OF NITRILOTRI(METHYLENE)PHOSPHONIC ACID

In this work the conditions for synthesis of copper nanoparticles by sodium tetrahydroborate in the presence of NTF are optimized. It is proved that the most favorable conditions for the reduction of copper in the solutions with its concentration of 2.0∙10-2 mol/l, are created when the concentration of tetrahydroborate sodium is three to four- fold exceeded, the titratable alkalinity is 5.3∙10-2-10.3∙10-2 mol/l, the temperature is 60 °C and the ratio of cation and chelate is equimolar. The method of photon correlation spectroscopy has confirmed the obtaining of copper nanoparticles with hydrodynamic radius of 25 nm, including shell stabilizers. The immutability of the size of bass for at least 72 h has been revealed.

The presence of inorganic calcium in pediatric parenteral admixtures.

Newborn infants and small children require large amounts of calcium and phosphate in a low volume of solution which can increase the risk of precipitation of calcium phosphate. Calcium gluconate is the predominant calcium salt form employed in parenteral nutrition (PN) compounding due to its solubility profile with phosphate. Unfortunately, calcium gluconate contains higher levels of aluminum contamination than calcium chloride, resulting in an increased potential for aluminum toxicity in patients receiving traditional PN. The physicochemical stability of 30 total parenteral admixtures containing inorganic calcium salts was evaluated. Parenteral admixtures were prepared in one-chamber ethylene vinyl acetate bags: amino acids, glucose, electrolytes including only inorganic calcium salt and 20% (w/w) lipid emulsions (SMOFlipid®, Omegaven® or Lipofundin MCT/LCT®) were placed together in a one chamber bag. Admixtures were stored at +4 °C for up to eight days after preparation. Visual observations, globule size distribution (using optical microscopy, laser diffraction and photon correlation spectroscopy methods), pH analysis and zeta potential measurements were performed. The physicochemical stability of 29 of parenteral admixtures in the presence of inorganic calcium salt was confirmed. One admixture was deemed unsuitable for use in clinical practice due to the coalescence of oil droplets. Despite the presence of inorganic calcium salts, pediatric parenteral admixtures were stable up to eight days of storage. Due to presence of multiple components and a high risk of incompatibilities, physicochemical studies should be performed for each admixture before use in clinical practice.

Возможности метода фотонной корреляционной спектроскопии в изучении процессов ассоциатообразования

Возможности метода фотонной корреляционной спектроскопии в изучении процессов ассоциатообразования

INFLUENCE OF EMULATOR'S NATURE ON DISPERSION AND STABILITY OF ARTIFICIAL LATEX

In this paper, we consider methods for producing artificial latexes based on butadiene-styrene thermoplastic elastomer in the presence of cationic surfactants, as well as their mixtures with nonionic and silicone surfactants. The obtained results are compared for the particle size distribution, and conclusions are drawn about the stability of the polymer suspension. The size of particles of polymer suspensions was determined by the method of photon correlation spectroscopy (dynamic light scattering) using a laser particle analyzer. This method allows us to consider the properties of the resulting polymer suspensions and directly draw conclusions about the effect of nature and the concentration of surface active substances on the stability of the resulting latexes. It can be assumed that in this case, structural- mechanical and electrostatic barriers form in the surface layers of the particles. The combined action of these barriers has made it possible to obtain stable polymer emulsions. Thus, it can be concluded that the used surfactant mixtures make it possible to increase the stability of artificial latexes in the stages of emulsification and distillation.

Nanosecond X-Ray Photon Correlation Spectroscopy on Magnetic Skyrmions.

We report an x-ray photon correlation spectroscopy method that exploits the recent development of the two-pulse mode at the Linac Coherent Light Source. By using coherent resonant x-ray magnetic scattering, we studied spontaneous fluctuations on nanosecond time scales in thin films of multilayered Fe/Gd that exhibit ordered stripe and Skyrmion lattice phases. The correlation time of the fluctuations was found to differ between the Skyrmion phase and near the stripe-Skyrmion boundary. This technique will enable a significant new area of research on the study of equilibrium fluctuations in condensed matter.

Influence of dispersing additive on asphaltenes aggregation in model system

The work is devoted to investigation of the dispersing additive influence on asphaltenes aggregation in the asphaltenes-toluene-heptane model system by photon correlation spectroscopy method. The experimental relationship between the onset point of asphaltenes and their concentration in toluene has been obtained. The influence of model system composition on asphaltenes aggregation has been researched. The estimation of aggregative and sedimentation stability of asphaltenes in model system and system with addition of dispersing additive has been given.

Reliability of thermal conductivity measurement of liquids by using transient hot-wire, photon-correlation spectroscopy and the laser flash method

Measuring the thermal conductivity of liquids is important, but not easy, because of the complexity of and the natural convection in liquids, and reliable thermal conductivity measurements in liquids under various sample conditions is essential for data accuracy. We have introduced and developed a validation chain for measuring the thermal conductivity of liquids by using three different experimental methods: the transient hot-wire (THW), the photon correlation spectroscopy (PCS) and the laser flash (LF) methods in the temperature range from −30 to 90 °C. We checked the performance of the validation chain developed in this study by measuring the thermal conductivity of liquid toluene. We found good agreement between the thermal conductivity data obtained by using the THW, PCS and LF methods. To demonstrate the use of this validation chain for measurements of thermophysical properties in liquids, we also showed its use in measuring the specific heat of a volatile liquid, toluene which can be extracted from thermal conductivity, thermal diffusivity, and density measurements without any effects of volatilization.

ИССЛЕДОВАНИЕ НАНОРАЗМЕРНЫХ ЧАСТИЦ СУСПЕНЗИЙ МЕТОДОМ ДИНАМИЧЕСКОГО И СТАТИЧЕСКОГО РАССЕЯНИЯ ИК СВЕТА

The possibility of the particle size measuring suspensions by means of the method of photon correlation spectroscopy. Graphs are given of the statistical distributions of the measured parameters of the two tested types of dispersed media. Studies have been shown that the method allows obtain data about the particle size.

SO2 carry-over and sulphur formation in a SO2-depolarized electrolyser

SO2-depolarized electrolysis (SDE) is considered as one of the most efficient hydrogen production methods. To maximize H2 production in SDE, the phenomena occurring in the cell need to be understood and controlled. In this work, electrochemically driven SO2 carry-over and elemental sulphur formation in cathode space are analysed by various methods: electrochemical, titration and photon correlation spectroscopy (PCS) under different conditions during SDE operation. The results indicate that SO2 carry-over is a fast process in an operating SDE and is difficult to control with only working parameter optimization. The PCS method provides SO2 carry-over information at early stages compared to other methods. Moreover, PCS might be further implemented as an in situ method for SDE system control.

The behavior of the diffusion coefficients in salting of herring in a fixed brine at subzero temperatures

The relevance of herring brine salting at subzero temperatures, taking into account the positive dynamics of its catching, its reserves, a favorable cooling effect on the suppression of microorganizms activity, improvement of product quality and increasing of storage time are indicated in this paper. Changes in such a significant characteristics as the diffusion coefficient in the process of salting at subzero temperatures were studied. Method of photon correlation spectroscopy, based on the Rayleigh scattering of radiation from the substance was used for the study. The experimental diffusion coefficient dependences on the depth of penetration of the salt in brine, skin and meat of herring at temperatures ranging from -16 ° C to -6 ° C were obtained. They are of wave-like nature. The dependence of the diffusion coefficients on subzero temperature ranging from -18 ° C to 0 ° C, and having a harmonic form was also obtained in the work. The resulting temperature gradient is a source of perturbations, giving rise to thermoconvective waves. According to the theoretical research of Academician A.V. Lykov and chemical processes occurring at the border (skin) of phase separation using the basic equation of thermochemistry - Gibbs law, mechanism of thermoconvective waves influencing the diffusion coefficient is explained. A relation between the diffusion coefficients with the size of the diffusing particles, having hyperbolic character in the temperature range from -18 ° C to 0 ° C in the in brine, skin and meat of herring was determined . The possibility of acceleration of salting by means of mechanical impact on the object under study (in particular sound or ultrasound) was expressed. The destruction of the diffusing particles, representing the union of Na+ and Cl- with water molecules, increases the diffusion coefficient.

The behavior of the diffusion coefficients in salting of herring in a fixed brine at subzero temperatures

The relevance of herring brine salting at subzero temperatures, taking into account the positive dynamics of its catching, its reserves, a favorable cooling effect on the suppression of microorganizms activity, improvement of product quality and increasing of storage time are indicated in this paper. Changes in such a significant characteristics as the diffusion coefficient in the process of salting at subzero temperatures were studied. Method of photon correlation spectroscopy, based on the Rayleigh scattering of radiation from the substance was used for the study. The experimental diffusion coefficient dependences on the depth of penetration of the salt in brine, skin and meat of herring at temperatures ranging from -16 ° C to -6 ° C were obtained. They are of wave-like nature. The dependence of the diffusion coefficients on subzero temperature ranging from -18 ° C to 0 ° C, and having a harmonic form was also obtained in the work. The resulting temperature gradient is a source of perturbations, giving rise to thermoconvective waves. According to the theoretical research of Academician A.V. Lykov and chemical processes occurring at the border (skin) of phase separation using the basic equation of thermochemistry - Gibbs law, mechanism of thermoconvective waves influencing the diffusion coefficient is explained. A relation between the diffusion coefficients with the size of the diffusing particles, having hyperbolic character in the temperature range from -18 ° C to 0 ° C in the in brine, skin and meat of herring was determined . The possibility of acceleration of salting by means of mechanical impact on the object under study (in particular sound or ultrasound) was expressed. The destruction of the diffusing particles, representing the union of Na+ and Cl- with water molecules, increases the diffusion coefficient.

Preparation of Poly Acrylic Acid-Poly Acrylamide Composite Nanogels by Radiation Technique.

Nanogel, a nanoparticle prepared from a cross-linked hydrophilic polymer network, has many biomedical applications. A radiation technique has recently been introduced as one of the appropriate methods for the preparation of polymeric nanogels due to its additive-free initiation and easy control procedure. We have investigated the formation of nano-sized polymeric gels, based on the radiation-induced inter- and intra-molecular cross-linking of the inter-polymer complex (IPC) of polyacrylamide (PAAm) and polyacrylic acide (PAAc). The results indicated that the prepared polymeric complex composed of PAAm and PAAc was converted into nanogel by irradiation under different doses (1, 3, 5 and 7 kGy). This was due to inter- and intra-molecular cross-linking at the range of 446-930 nm as characterized by the photon correlation spectroscopy method. Increasing the irradiation dose reduced the size of nanoparticles to 3 kGy; however, the higher doses increased the size and size distribution. Scanning electron microscopy images indicated the nanogel formation in the reported size by particle size and showed the microcapsule structure of the prepared nanogels. Biocompatibility of nanogels were assessed and proved by MTT assay. It was concluded that low dose irradiation can be successfully applied for nanometre-ranged hydrogel.