Colloid Journal最新文献

The formation of a fibrin film at the sites of cuts and wounds is a complex biochemical process that involves fibrinogen and thrombin as the main components, as well as other enzymes and proteins. Dynamic surface properties of adsorption films obtained from the solution, which contains factors VIII, XIIIa, von Willebrand factor and fibronectin, differ from the fibrinogen adsorption films and fibrin films obtained from a solution containing only fibrinogen and thrombin. Their dynamic surface elasticities exceed the corresponding values for fibrinogen (80 and 55 mN/m, respectively); however, they appear to be lower than value for fibrin prepared from pure components (115 mN/m). The surface pressures achieved for the adsorption films obtained from hemostatic glue (27 mN/m) exceed those for both aforementioned systems (14 mN/m). As follows from the Brewster angle microscopy and scanning electron microscopy data, significant changes in the morphology of the resulting films are responsible for the observed effect.

The work is devoted to the analysis of the nonlinear effects resulting from the influence of excess volumes of intergranular boundaries on the structure of segregations of impurity atoms in polycrystals. It is shown that the adsorption isotherm can describe the nonuniformities in the distribution of impurity atoms in the plane of an intergranular boundary. This suggests the existence of adsorption sites at the internal boundaries of polycrystals. It is proven that an excess volume of intergranular boundaries is the main parameter determining the magnitude of impurity segregations at the boundaries.

The objective of this study is to enhance the comprehension of the mechanism of enzymatic gelation in milk by investigating statistically significant changes in milk viscosity and carrying out corresponding electron microscopic studies of the process of structure formation at the enzymatic stage of coagulation using various enzyme preparations. Employing a non-destructive method (Hot-Wire) to monitor viscosity, we were able to confirm a decrease in viscosity during the middle of this stage and identify a previously undescribed peak in viscosity change at the end of the enzymatic stage. By conducting parallel studies utilizing transmission electron microscopy and various methods of specimen preparation, it was possible to discover that a hierarchical transformation process in the protein component of milk started at the end of the enzymatic stage of gelation in milk. This process is triggered by a cooperative conformational transition in casein micelle clusters, which leads to a series of increasingly energy-intensive reactions resulting in the transformation of loosely bound micelle clusters into denser aggregates. The final structure of the milk gel primarily consists of the previously formed individual micelle aggregates. It was noted that no changes in the microstructure of the milk gel were observed during the enzymatic stage of gelation when milk-clotting enzymes (MCEs) of animal, plant, and microbial (GMO) origins were used. Furthermore, investigations into the molecular weight distribution of soluble protein substances in samples generated with different types of MCEs revealed that the enzyme derived from the fungi of Rhizomucor miehei had a greater proteolytic effect on milk proteins compared to other variants of MCEs.

The viscoelastic properties and structure of solutions of mixed wormlike micelles based on a zwitterionic surfactant, oleylamidopropyldimethylcarboxybetaine (OAPB), and positively charged oleylamidopropyldimethylamine (OAPA) have been studied at different ratios between the components. At a small fraction of the cationic surfactant, OAPA, the solution exhibits viscoelastic properties characteristic of semidiluted solutions of entangled wormlike micelles, the presence of which has been confirmed by cryogenic electron microscopy data. It has been found that, as the molar fraction of the charged surfactant increases to 0.1, the viscosity and relaxation time of the solutions decrease by a factor of three, and the values of the storage modulus remain unchanged at short stress action times. The studied surfactants have a similar structure; therefore, when replacing zwitterionic OAPB molecules by positively charged OAPA molecules, the main factor of variations in the properties and structure is the enhancement of the electrostatic repulsion on the micelle surface. It has been shown that this factor leads to a decrease in the average length of micelles and an increase in their number, which have a weak effect on the rheological properties of the system as long as the length of the micelles is larger than the length of the subchains in the network. With an increase in the molar fraction of OAPA from 0.1 to 0.5, the viscosity and relaxation time drop drastically by several orders of magnitude and the viscoelastic response of the solution is lost; i.e., the network is destroyed. This transition from a semidilute solution to a dilute one is explained by a decrease in the length of the wormlike micelles and the formation of spherical ones. Cryogenic electron microscopy images have confirmed the formation of a mixture of long and short wormlike micelles with spherical micelles at an OAPA molar fraction of 0.5.

Human industrial activity is accompanied by the formation of vast volumes of water contaminated with radionuclides, including radium-226, which create serious danger to people. Graphene nanostructures are among the most promising materials for purifying water from radionuclides. This work has been devoted to investigating the efficiency of few-layer graphene synthesized under conditions of self-propagating high-temperature synthesis from cellulose and wastes of the woodworking industry (technical lignin, tree bark) for purifying water from radium-226. The key advantage of the method chosen for synthesis of few-layer graphene is the possibility to synthesize large volumes of the material at an acceptable cost, which is extremely important for industrial applications. It has been found that the synthesized samples of few-layer graphene can efficiently purify water from radium-226 (the degree of sorption is higher than 99%). It has also been shown that the degree of desorption upon repeated washing with water does not exceed 0.5%.

Coagulation of polydisperse detonation nanodiamond (DND) hydrosol containing primary aggregates with a prevailing average size in a range of 20–200 nm has been studied experimentally and theoretically within the framework of the classical and extended DLVO theory as depending on the concentrations of an indifferent electrolyte (NaCl) and potential-determining ions (pH). It has been shown that the surface of DND particles is charged due to the ionization of ionogenic amphoteric hydroxyl and acidic carboxyl groups located on it. The isoelectric point of the detonation nanodiamond particles has been found to correspond to pH 7.5. It has been revealed that the main stabilizing factor of the DND hydrosol is electrostatic. It has been shown that the stability and coagulation of the sol can be described within the framework of the extended DLVO theory using the effective Hamaker constant for primary porous aggregates and taking into account the initial polydispersity of the DND particles.

Polyimide films with molecular imprints of erythrosine and indigocarmine have been obtained. The structure and morphology of the film surfaces have been studied by scanning probe microscopy and IR spectroscopy. It has been found that the surface roughness of molecularly imprinted polymers (MIPs) increases, while the relief height amounts to 3–4 nm. The removal of template molecules leads to a redistribution of pores over sizes in the polymers with molecular imprints. The adsorption of dyes by MIP films has been carried out under static conditions. The degrees of extraction and the imprinting factors have been calculated for polymers with molecular imprints of the dyes. The high values of these parameters indicate the selectivity of MIPs to the target template molecules.

Improving thermal ice melting efficiency is very important in the practical application of anti-icing surfaces. This work investigated the thermal ice melting performance of micro-nano-structured surfaces fabricated by femtosecond laser. To the best of our knowledge, we found that the micro-nano-structured surfaces significantly improve the ice melting time for the first time. The shortest melting time was on the porous micro-nano-structured surface, about one third of the original surface. Moreover, it was proven that the accelerated ice melting surface had good durability. The research in this paper showed that the micro-nano-structured surfaces are very suitable for the surface that needs to be heated to melt ice, providing essential guidance for the design of the anti-icing surface.

In this research work, a new biocompatible microemulsion containing castor oil has been formulated to increase the solubility of celecoxib, as a well-known anti-inflammatory drug. In this formulation castor oil has also anti-inflammatory properties. The proposed oil-in-water microemulsion composed of Tween 80 as surfactant, isobutanol as co-surfactant, and castor oil as the oil phase. In the first step, the phase diagrams of the proposed colloid systems with surfactant to co-surfactant mass ratios of 4 : 1 and 2 : 1 were prepared at ambient temperature. Then, using the obtained phase diagrams, the appropriate formulations were selected by combining different percentages of water, oil, surfactant and co-surfactant in the microemulsion region. Some of physico-chemical properties, such as electrical conductivity, density, refractive index, surface tension and particle size of the selected microemulsion formulations have been determined at 298 K. After that, the solubility of celecoxib in the selected formulations was determined and compared with other reported microemulsion formulations. Interesting results from this section indicated that the solubility of celecoxib significantly increased compared to pure water and the previous proposed formulations. The results of this study can be used to provide suitable formulations based on the biocompatible microemulsions for celecoxib in pharmaceutical industry.

Nickel oxide nanoparticles (NiO NPs) are synthesized using olive leaf extract (OLE), which contains a range of polyphenols. These polyphenols serve as both reducing and capping agents, stabilizing the nanoparticles. Aqueous nickel acetate is employed as a precursor. Simultaneously, exfoliated graphene (EG) is obtained via electrochemical exfoliation of graphite in aqueous solutions. These materials were employed as electroactive components in supercapacitor applications. Characterization of NiO and EG involved thermogravimetric analysis (TGA), X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and scanning/transmission electron microscopy (SEM/TEM), alongside Brunauer−Emmett−Teller (BET) analysis, confirming the formation of crystalline NiO NPs with a cubic phase and Fm-3m space group. Micrographs revealed nanoscale dimensions for both NiO and EG with a substantial surface area, as verified by BET analysis. Symmetric (NiO/NiO, EG/EG) and asymmetric (NiO/EG) supercapacitors were fabricated using the doctor blade method. Electrode evaluation, employing field-emission scanning electron microscopy FESEM, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), demonstrated promising morphological and electrochemical characteristics. At low scan rates, both symmetric and asymmetric supercapacitors exhibited a notable gravimetric capacitance (221, 111, and 162 F g^–1 at 1 mV s^–1). Additionally, they revealed higher power density (173, 137, and 161 W kg^–1 at 10 mV s^–1), showcasing pseudocapacitive and electric double-layer capacitor (EDLC) behavior for NiO NPs and EG, respectively. This research significantly contributes valuable insights by presenting a sustainable synthesis route for NiO NPs, developing high-performance supercapacitor electrodes, and achieving a comprehensive understanding of the electrochemical behavior of NiO NPs and EG.