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This article contains the information about the structure, functioning, and regeneration of type 2 pneumocytes. The composition of the surfactant, the processes of its synthesis, formation, secretion, distribution and redistribution of its components, as well as the biological role of the surfactant in the functioning of the lungs are described in detail. The information about the development of the surfactant system of the lungs during embryogenesis is also included. Objectives. To review modern literature on the structure and functions of the surfactant system of the lungs, the organization and structure of the surfactant, the mechanism of surfactant formation, the embryogenesis of the respiratory section, to characterize the structure and processes of the functioning of type 2 pneumocytes, as well as the processes of synthesis and secretion of the surfactant, its biological role in the functioning of the lungs. The relevance of the chosen topic is connected with a high level of the respiratory system pathology including a high incidence of respiratory system organs diseases in early childhood, associated with an insufficient level of the surfactant maturity. The problem of pulmonary pathology in newborns, including premature babies, largely determines the level of infant morbidity and mortality.

We studied the complexation of titanium(IV) with 2,2',3,4-tetrahydroxy-3'-nitro-5'-sulfoazobenzene (R) in the presence of cationic surfactants (CSs) cetylpyridinium chloride (CPCl), cetylpyridinium bromide (CPBr), and cetyltrimethylammonium bromide (CTMABr). In the presence of cationic surfactants, mixed-ligand complexes are formed with the ratio of components $${\text{Ti}}({\text{OH}})_{{\text{2}}}^{{{\text{2}} + }}$$ : H4R– : CS = 1 : 2 : 2. The optimal pH values of the complex formation were found: 4.5 for ( $${\text{Ti}}({\text{OH}})_{{\text{2}}}^{{{\text{2}} + }}$$ (H3R2–)2 and 3.5 for mixed-ligand complexes ( $${\text{Ti}}({\text{OH}})_{{\text{2}}}^{{{\text{2}} + }}$$ (H3R2–)2(CPCl)2, ( $${\text{Ti}}({\text{OH}})_{{\text{2}}}^{{{\text{2}} + }}$$ (H3R2–)2(CPBr)2, and ( $${\text{Ti}}({\text{OH}})_{{\text{2}}}^{{{\text{2}} + }}$$ (H3R2–)2(CTMABr)2. We also investigated the effect of time, temperature, and concentrations of the reacting components on the formation of mixed-ligand complexes. The Beer law is observed in the concentration range of ( $${\text{Ti}}({\text{OH}})_{{\text{2}}}^{{{\text{2}} + }}$$ (H3R2–)2, ( $${\text{Ti}}({\text{OH}})_{{\text{2}}}^{{{\text{2}} + }}$$ (H3R2–)2(CPCl)2, ( $${\text{Ti}}({\text{OH}})_{{\text{2}}}^{{{\text{2}} + }}$$ (H3R2–)2(CPBr)2, and ( $${\text{Ti}}({\text{OH}})_{{\text{2}}}^{{{\text{2}} + }}$$ (H3R2–)2(CTMABr)2 of 0.10–1.8, 0.10–1.92, 0.10–1.92, and 0.08–1.92, respectively. The effect of foreign ions and masking substances on the determination of titanium(IV) as mixed-ligand complexes was studied. We developed a procedure for the spectrophotometric determination of trace amounts of titanium in sea sand taken from the Caspian Sea coast near the Turkan village.

In this work, the issue of surfactant adsorption (SA) onto solid surfaces was attempted through surfactant encapsulation via host-guest interactions using β-CD. Formulations of non-encapsulated (No...

This study discusses the mechanistic details of the cationic micellar transition (growth) in a mixed surfactant system. The aqueous mixed surfactant solution contains cationic micelles at a concent...

Surfactant flooding is one of the chemical enhanced oil recovery (CEOR) techniques that can be used to improve oil recovery. The surfactant injection reduces the oil-water interfacial tension and mobilizes residual oil towards the producing well. In this paper, the performance of alkyl ether carboxylate (AEC) and calcium lignosulfonate (CLS) in individual and mixed surfactant systems were investigated based on their ability to reduce the interfacial tension through a spinning drop method. The interfacial tensions of individual and mixed surfactant systems in different brine systems were measured against decane at 25°C and 98°C. The results show that the individual and mixed surfactant systems in 3.5 wt.% NaCl brine has a significant reduction in interfacial tension at 98°C. In contrast, the presence of hardness in 2.5 wt.% NaCl and 1.0 wt.% MgCl2 brine reduces the interfacial tension of the individual AEC surfactant system and mixed surfactant system significantly at 98°C except for the individual CLS system. Meanwhile, the interfacial tension of mixed surfactant system decreases with increasing surfactant concentration in two brine systems and at 98°C. The findings show the significant application of the AEC and CLS surfactant mixture considering the harsh reservoir conditions for the chemical enhanced oil recovery application.

Surfactants are very important surface-active agents in implementation of chemical enhanced oil recovery for oil-water interfacial tension and wettability alteration. However, the high adsorption of surfactant on reservoir rock reduces the efficiency of surfactant flooding. Conventionally, inorganic alkali has been introduced to reduce adsorption of surfactant, but alkali will lead to the formation of emulsion, formation damage and scaling. Therefore, lignosulfonate, a sacrificial agent has been introduced as an alternative to inorganic alkali. In this paper, the critical micelle concentration (CMC) and dynamic interfacial tension (IFT) behavior of a pure and binary system of internal olefin sulfonate (IOS) and lignosulfonate (LS) at brine-decane interfaces are determined by using a spinning drop method. The physicochemical properties of pure and binary of IOS and LS system are determined by conductivity and pH measurements. The CMC value of IOS in 3.5 wt% brine salinity is higher compared to LS due to the isomeric branched of IOS which can occupy a larger area per molecules. The dynamic interfacial tension of IOS shows the fast adsorption of surfactant molecules to the brine-decane interfaces. This is indicated by the fast equilibrium interfacial tension reached by IOS. In comparison, the LS pure system shows decreasing behavior of dynamic interfacial tension. The fast adsorption at the interfaces is only reached for higher LS concentrations. The synergy effect between IOS and LS system shows a reduction in the interfacial value with LS optimum concentration of 0.6 wt%. The drop in conductivity and pH values indicated the development of a tightly packed lamellar liquid crystalline structure. These physicochemical properties are in agreement with the dynamic interfacial tension behavior of the IOS and LS system. This study has demonstrated the significant impact of the LS addition in reducing the dynamic interfacial tension of the surfactant system.

In this paper, we propose a high order numerical scheme to simulate the binary fluid--surfactant system by combining the semi-implicit spectral deferred correction (SDC) method and the energy stabl...

Dissipative particle dynamic (DPD) simulations were performed to study the interfacial properties such as interfacial tension, area compressibility, stress profile, and conformation of surfactant a...

Droplet-confined assembly is a powerful tool to fabricate functional nanostructures of block copolymers (BCPs), where the interfacial interaction plays a crucial role. Here, we report an unconventional strategy of using interfacial phase separation to control this assembly. The key lies in the use of an elaborately designed binary surfactant system to tune the interfacial configuration of droplets and realize an asymmetrically directed assembly of BCPs inside droplets, which finally creates unprecedented Janus onion particles with solid surfactant-like properties, e.g., as stabilizers for Pickering emulsions. The formation of Janus onions is due to the strong longitudinal selective interaction and the strong lateral phase separation at the droplet interfaces, provided by our surfactant system. This concept of interfacial phase separation directed assembly not only enriches the routes to controllable assembly of BCPs, but also offers an innovative paradigm to construct distinct regions on droplet surfaces, illuminating potential functions such as smart encapsulation and delivery.

This paper reports the hydrodynamic characteristics of CNT nanofluids prepared using mixed surfactant system flowing through helically coiled tubes under laminar conditions. The curvature ratio was...

Integrated and environmentally friendly methods for extraction and enrichment of natural products have gained increasing interests. The proposed preparation process provides the possibility that extraction and pre-concentration for astragalosides from Radix Astragali roots can be conducted with the surfactant aqueous system in one single procedure. The formulated surfactant system composing of 2% TX-114 as surfactant and 0.03% (w/v) of Gemini 16-5-16 as co-surfactant showed higher extraction efficiency with ultrasonic-assisted method and four astragalosides could be enriched by the cloud point phenomenon of surfactant. This work represents a valuable alternative for the eco-friendly extraction and enrichment of secondary metabolites from plants.

Submilligram-scale separation of near-zigzag single-chirality carbon nanotubes has been achieved by gel chromatography., Mass production of zigzag and near-zigzag single-wall carbon nanotubes (SWCNTs), whether by growth or separation, remains a challenge, which hinders the disclosure of their previously unknown property and practical applications. Here, we report a method to separate SWCNTs by chiral angle through temperature control of a binary surfactant system of sodium cholate (SC) and SDS in gel chromatography. Eleven types of single-chirality SWCNT species with chiral angle less than 20° were efficiently separated including multiple zigzag and near-zigzag species. Among them, (7, 3), (8, 3), (8, 4), (9, 1), (9, 2), (10, 2), and (11, 1), were produced on the submilligram scale. The spectral detection results indicate that lowering the temperature induced selective adsorption and reorganization of the SC/SDS cosurfactants on SWCNTs with different chiral angles, amplifying their interaction difference with gel. We believe that this work is an important step toward industrial separation of single-chirality zigzag and near-zigzag SWCNTs.

Barium titanate (BaTiO3) peapod nanocomposites were prepared by the controlled capture of nanoparticles (NPs) in scrolling hexaniobate (HNB) nanosheets. BaTiO3 NPs and proton-exchanged potassium hexaniobate were treated solvothermally at 220 ��C for 6 h in toluene to produce linear NP chains confined within multiwalled HNB nanoscrolls. This method consistently produced nanopeapods with average filling fractions greater than 70%. The controlled introduction of nanocomponents along with a combination of oleylamine and oleic acid surfactants was critical to the success of these reactions. The ability to form BaTiO3@HNB significantly expands the number of important peapod composites accessible by the controlled NP capture.

Due to the short time constant of the spin-spin relaxation process, there is a limitation in the preparation of NMR sample solution for large proteins. To overcome this problem, reverse micelle systems are used. Here, molecular dynamics simulation was used to study the structure of flavodoxin in a quaternary mixture of 1-decanoyl-rac-glycerol, lauryldimethylamine-N-oxide, pentane and hexanol. Hexanol was used as co-solvent. Simulations were performed at three different co-solvent concentrations. The proportion of components in the mixture was selected according to experimental conditions. For comparison, simulation of flavodoxin in water was also performed. The simulation results show that the C$\alpha$-RMSD for the protein in water is less than for the surfactant mixture. Also, the radius of gyration of flavodoxin increased in the presence of surfactants. The distance between the two residues trp-57 and phe-94, as a measure of protein activity, was obtained from the simulations. The results showed that in the surfactant mixtures this distance increases. Analysis of the secondary structure of the protein shows that the N-terminal part of the flavodoxin is more affected by surfactants. The flavodoxin diffusion coefficient in the surfactant mixture decreased in relation to its diffusion coefficient in water.

This study was focused on a ternary complex system composed of hexadecyl diphenyl ether disulfonate (C16-MADS), dodecyl dimethyl hydroxyethyl ammonium chloride (K3) and fatty alcohol polyoxyethylene ether (AEO9). The binary mixture C-K consisting of C16-MADS and K3 was investigated and the maximum synergism was obtained when the mole ratio was 0.33:0.67. Subsequently, AEO9 was added to the binary C-K complex system to investigate whether the behavior of the new complex system, in which C-K is thought to be a surfactant, can be explained by the theory of regular solution. The maximum synergism was achieved when the molar ratio of C-K and AEO9 was 7:3. The regular solution theory could well explain the synergism in mixed micelle formation and the synergism in surface tension reduction efficiency, but the synergism in surface tension reduction effectiveness did not match with the experimental data. So, there still exist some deficiencies in the application of the regular solution theory to a complex system of three surfactants.